Continuation of the table. 3.1
Continuation of the table. 3.1
End of table. 3.1
Among the transmissions of motion from the drive to the working parts of the machine, mechanical transmissions are most widespread (Fig. 3.1).
According to the method of transmitting motion from the driving element to the driven element, mechanical transmissions are divided as follows: gear transmissions with direct contact (gear - Fig. 3.1, a; worm - Fig. 3.1, b; ratchet; cam) or with a flexible connection (chain); friction transmissions with direct contact (friction) or with a flexible connection (belt - Fig. 3.1, c).
The main kinematic parameter characterizing all types of mechanical transmissions of rotational motion is the gear ratio - the ratio of the number of teeth of a larger wheel to the number of teeth of a smaller one in a gear drive, the number of teeth of a wheel to the number of worm runs in a worm gear, the number of teeth of a large sprocket to the number of teeth of a small one in a chain drive transmission, as well as the diameter of a large pulley or roller to the diameter of a smaller one in a belt or friction drive. The gear ratio characterizes the change in rotation speed in the transmission
where and is the rotation frequency of the driving I and driven II shafts, min -1 or s -1 (see Fig. 3.1, a, b and c).
So, for gears (see Fig. 3.1, A) and chain drives
where is the number of teeth of the larger gear or sprocket; - the number of teeth of the smaller gear or sprocket.
For worm gear (see Fig. 3.1, b)
where is the number of teeth of the worm wheel; - number of worm passes.
For belt drive (Fig. 3.1, c)
where is the diameter of the driven (larger) transmission pulley, mm; - diameter of the driving (smaller) transmission pulley, mm.
To convert rotational motion into translational motion or vice versa, a rack and pinion is used (Fig. 3.1, G) or helical (Fig. 3.1, d) gears. In the first case, the axis of rotational motion and the direction of translational motion are perpendicular, and in the second case they are parallel.
Gears that convert rotational motion into translational motion are characterized by the distance over which the moving element moves translationally per revolution of the drive shaft.
In a rack and pinion transmission (see Fig. 3.1, d) the movement of the rack per revolution of the gear wheel (gear)
where is the number of wheel teeth; - engagement module.
Rice. 3.1. Gears in machines: a - gear: I - drive shaft; - number of gear teeth; - rotation speed of the drive shaft; II - driven shaft; - number of wheel teeth; - driven shaft rotation speed; b - worm: and - rotation speed and number of worm passes, respectively; and are the rotation speed and number of wheel teeth, respectively; c - belt: and - rotation speed of the drive roller and its diameter, respectively; and are the rotation speed of the driven roller and its diameter, respectively; g - screw: - screw pitch; - direction of movement of the nut; d - rack: - direction of movement of the rack; - rack tooth pitch; - number of wheel teeth; - direction of wheel rotation
The screw-nut pair is used in the feed mechanisms of almost all machine tools. When you turn the screw one turn, the nut moves to the right or left (depending on the direction of the thread) one step. There are designs in which the nut is stationary, and the screw rotates and moves, as well as designs with a rotating and moving nut. For screw-nut transmission, movement of a progressively moving element
where is the propeller pitch, mm; - number of propeller passes.
When several gears are arranged in series, their total gear ratio is equal to the product of the gear ratios of the individual gears
where is the total gear ratio of the kinematic chain; - gear ratios of all elements of the kinematic chain.
The rotation speed of the last driven shaft of the kinematic chain is equal to the rotation speed of the drive shaft divided by the total gear ratio,
Movement speed (mm/min) of the final element (node) of the kinematic chain
where is the rotation speed of the drive shaft of the initial element; - displacement of the progressively moving element per revolution of the drive shaft, mm.
The mathematical expression of the relationship between the movements of the leading and driven elements (initial and final links) of the kinematic chain of a machine tool is called the kinematic balance equation. It includes components that characterize all elements of the chain from the initial to the final link, including those that transform motion, for example, rotational into translational. In this case, the balance equation includes the unit of measurement of the parameter (lead screw pitch - when using a screw-nut transmission or module - when using a gear-rack transmission) that determines the conditions for this transformation, millimeter. This parameter also allows you to coordinate the motion characteristics of the initial and final links of the kinematic chain. When transmitting only rotational motion, the equation includes dimensionless components (gear ratios of mechanisms and individual gears), and therefore the units of measurement of the motion parameters of the final and initial links are the same.
For machines with main rotational motion, the limiting values of spindle rotation speeds ensure processing of workpieces with a diameter of machined surfaces in the range from to .
The range of regulation of spindle speeds characterizes the operational capabilities of the machine and is determined by the ratio of the highest spindle speed of the machine to the lowest:
The rotation speed values from to form a series. In machine tool building, as a rule, a geometric series is used, in which adjacent values differ by a factor of (- denominator of the series: ). The following denominator values are accepted and normalized: 1.06; 1.12; 1.26; 1.41; 1.58; 1.78; 2.00. These values form the basis for the table series of spindle speeds.
3.2. Typical machine parts and mechanisms
Beds and guides. The supporting system of the machine is formed by the totality of its elements, through which the forces arising between the tool and the workpiece during the cutting process are closed. The main elements of the machine's supporting system are the bed and body parts (crossbars, trunks, sliders, plates, tables, supports, etc.).
Bed 1 (Fig. 3.2) is used for mounting parts and assemblies of the machine; moving parts and assemblies are oriented and moved relative to it. The bed, like other elements of the supporting system, must have stable properties and ensure, during the service life of the machine, the ability to process workpieces with specified modes and accuracy. This is achieved by the correct choice of bed material and its manufacturing technology, and the wear resistance of the guides.
Rice. 3.2. Machine beds: a - screw-cutting lathe; b - turning with program control; c - surface grinding; 1 - bed, 2 - guides.
For the manufacture of beds, the following basic materials are used: for cast beds - cast iron; for welded ones - steel, for the beds of heavy machine tools - reinforced concrete (sometimes), for high-precision machine tools - synthetic artificial material, made on the basis of crumbs of mineral materials and resin and characterized by minor temperature deformations.
Guides 2 provide the required relative position and the possibility of relative movement of units carrying the tool and the workpiece. The design of the guides for moving the unit allows only one degree of freedom of movement.
Depending on the purpose and design, there is the following classification of guides:
By type of movement - main movement and feed movement; guides for rearranging associated and auxiliary units that are stationary during processing;
Along the trajectory of movement - rectilinear and circular movement;
In the direction of the trajectory of movement of the node in space - horizontal, vertical and inclined;
By geometric shape - prismatic, flat, cylindrical, conical (only for circular motion) and their combinations.
Rice. 3.3. Examples of sliding guides: a - flat; 6 - prismatic; c - in the form of a “dovetail”
The most widely used are sliding guides and rolling guides (the latter use balls or rollers as intermediate rolling elements).
For the manufacture of sliding guides (Fig. 3.3) (when the guides are made as one piece with the frame) gray cast iron is used. The wear resistance of the guides is increased by surface hardening, hardness HRC 42...56.
Steel guides are overhead, usually hardened, with a hardness of HRC 58…63. Most often, steel 40X is used with hardening with HDTV 1, steel 15X and 20X - followed by carburization and hardening.
Reliable operation of the guides depends on protective devices that protect the working surfaces from dust, chips, and dirt (Fig. 3.4). Protective devices are made from various materials, including polymers.
Spindles and their supports. A spindle is a type of shaft that serves to secure and rotate a cutting tool or device that carries a workpiece.
To maintain processing accuracy during the specified service life of the machine, the spindle ensures the stability of the axis position during rotation and translational motion, and the wear resistance of the supporting, seating and basing surfaces.
Spindles, as a rule, are made of steel (40Kh, 20Kh, 18KhGT, 40KhFA, etc.) and are subjected to heat treatment (cementation, nitriding, volumetric or surface hardening, tempering).
To secure a tool or fixture, the front ends of the spindles are standardized. The main types of machine spindle ends are shown in table. 3.2.
Rice. 3.4. The main types of protective devices for guides: a - shields; b - telescopic shields; c, d and d - tape; e - harmonica-shaped bellows
Sliding and rolling bearings are used as spindle supports. The design diagram of adjustable sliding bearings, made in the form of bronze bushings, one of the surfaces of which has a conical shape, is shown in Fig. 3.5.
The sliding bearings of spindles use lubricant in the form of a liquid (in hydrostatic and hydrodynamic bearings) or gas (in aerodynamic and aerostatic bearings).
There are single and multi-wedge hydrodynamic bearings. Single wedge ones are the simplest in design (bushing), but do not provide a stable position of the spindle at high sliding speeds and low loads. This disadvantage is absent in multi-wedge bearings, which have several load-bearing oil layers covering the spindle neck evenly on all sides (Fig. 3.6).
Table 3.2
Main types of machine spindle ends
Rice. 3.5. Adjustable plain bearings: a - with a cylindrical spindle neck: 1 - spindle neck; 2 - split bushing; 3 - body; b - with a conical spindle neck: 1 - spindle; 2 - solid bushing
Rice. 3.6. Grinding wheel spindle support with hydrodynamic five-liner bearing: 1 - self-aligning inserts; 2 - spindle; 3 - clip; 4 - screw; 5 - rolling bearings; 6 - screws with a spherical support end; 7 - cuffs
Hydrostatic bearings - sliding bearings in which an oil layer between the rubbing surfaces is created by supplying oil under pressure from a pump - ensure high accuracy of the position of the spindle axis during rotation, have greater rigidity and provide fluid friction at low sliding speeds (Fig. 3.7 ).
Gas-lubricated bearings (aerodynamic and aerostatic) are similar in design to hydraulic bearings, but provide lower friction losses, which allows them to be used in supports of high-speed spindles.
Rolling bearings are widely used as spindle supports in machine tools of various types. There are increased demands on the rotational accuracy of spindles; therefore, bearings of high accuracy classes are used in their supports, installed with preload, which eliminates the harmful effects of clearances. The interference in angular contact ball and tapered roller bearings is created when they are installed in pairs as a result of the axial displacement of the inner rings relative to the outer ones.
This displacement is carried out using special structural elements of the spindle assembly: spacer rings of a certain size; springs ensuring constant preload force; threaded connections. In roller bearings with cylindrical rollers, the preload is created by deforming the inner ring 6 (Fig. 3.8) when tightening it onto the conical neck of the spindle 8 using a bushing 5 moved by nuts 1. The spindle bearings are reliably protected from contamination and leakage of lubricant by lip and labyrinth seals 7 .
Rolling bearings 4 are widely used as thrust bearings, fixing the position of the spindle in the axial direction and absorbing loads arising in this direction. The preload of the ball thrust bearings 4 is created by springs 3. The springs are adjusted using nuts 2.
Rice. 3.7. Hydrostatic bearing: 1 - bearing housing; 2 - spindle neck; 3 - pocket creating the bearing surface (arrows indicate the direction of supply of lubricant under pressure and its removal)
Rice. 3.8. Front support of the lathe spindle on rolling bearings: 1 - nuts; 2 - adjusting nuts; 3 - springs; 4 - thrust rolling bearings; 5 - bushings; 6 - inner ring of the roller bearing; 7 - seals; 8 - spindle
An example of the use of angular contact ball bearings to absorb axial loads is shown in Fig. 3.6. Preload is created by adjusting the position of the outer
bearing rings 5 using nut 4.
Typical mechanisms for carrying out translational motion. Translational motion in the machines under consideration is provided by the following mechanisms and devices:
Mechanisms that convert rotational motion into translational motion: a gear wheel or a worm with a rack, a lead screw - nut and other mechanisms;
Hydraulic devices with a cylinder-piston pair;
Electromagnetic devices such as solenoids, used mainly in drives of control systems. Let us give examples of some of these mechanisms (for symbols, see Table 3.1).
The gear-rack pair has a high efficiency, which makes it suitable for use in a wide range of rack speeds, including in main motion drives that transmit significant power, and in auxiliary motion drives.
A worm-and-rack gear differs from a gear-rack pair in its increased smoothness of movement. However, this transmission is more difficult to manufacture and has lower efficiency.
The lead screw - nut mechanism is widely used in drives for feeds, auxiliary and installation movements and provides: a small distance over which the moving element moves per one revolution of the drive; high smoothness and accuracy of movement, determined mainly by the accuracy of manufacturing of the pair elements; self-braking (in pairs of screw-sliding nut).
In the machine tool industry, six accuracy classes are established for lead screws and sliding nuts: 0 - the most accurate; 1, 2, 3, 4 and 5 classes, with the help of which the permissible deviations in pitch, profile, diameters and surface roughness parameters are regulated. The design of the nuts depends on the purpose
mechanism.
Due to low efficiency, the lead screw - sliding nut pairs are replaced with rolling screw pairs (Fig. 3.9). These pairs eliminate wear, reduce friction losses, and can eliminate clearances by creating preload.
The disadvantages inherent in pairs of screw-sliding nut and screw-rolling nut, due to the peculiarities of their operation and manufacture, are eliminated in the hydrostatic screw-nut transmission. This pair operates under conditions of friction with a lubricant; Transmission efficiency reaches 0.99; the oil is fed into pockets made on the sides of the nut threads.
Typical mechanisms for performing periodic movements. During operation, some machines require periodic movement (change of position) of individual units or elements. Periodic movements can be carried out by ratchet and maltese mechanisms, cam mechanisms and with overrunning clutches, electric, pneumatic and hydraulic mechanisms.
Ratchet mechanisms (Fig. 3.10) are most often used in the feed mechanisms of machine tools, in which periodic movement of the workpiece, cutting (cutter, grinding wheel) or auxiliary (diamond for dressing the grinding wheel) tool is carried out during the overrun or reverse (auxiliary) stroke (in grinding and other machines).
In most cases, ratchet mechanisms are used for linear movement of the corresponding unit (table, caliper, quill). With the help of a ratchet transmission, circular periodic movements are also carried out.
Couplings are used to connect two coaxial shafts. Depending on the purpose, there are non-disengaging, interlocking and safety couplings.
Non-disengaging couplings (Fig. 3.11, a, b, c) are used for a rigid (blind) connection of shafts, for example, a connection using a sleeve, through elastic elements or through an intermediate element that has two mutually perpendicular protrusions on the end planes and makes it possible to compensate for the misalignment of the connected shafts .
Rice. 3.9. Pair of screw-friction nut: 1, 2 - nut, consisting of two parts; 3 - screw; 4 - balls (or rollers)
Rice. 3.10. Ratchet mechanism diagram: 1 - ratchet; 2 - dog; 3 - shield; 4 - traction
Interlocking couplings (Fig. 3.11, d, e, f) are used for periodic connection of shafts. The machines use interlocking cam couplings in the form of disks with end teeth-cams and gear couplings. The disadvantage of such meshed couplings is the difficulty of engaging them when there is a large difference in the angular velocities of the driving and driven elements. Friction clutches do not have the disadvantages inherent in cam clutches and allow them to be engaged at any rotation speed of the driving and driven elements. Friction clutches come in cone and disk types. In main motion and feed drives, multi-disc clutches are widely used, transmitting significant torques with relatively small overall dimensions. The compression of the driving disks with the driven ones is carried out using mechanical, electromagnetic and hydraulic drives.
Rice. 3.11. Couplings for connecting shafts: a - rigid sleeve type; b - with elastic elements; c - cross-movable; g - cam; d - multi-disc with mechanical drive: 1 - washer; 2 - pressure disk; 3 - balls; 4 - fixed bushing; 5 - bushing; 6 - nut; 7 - springs; e - electromagnetic: 1 - splined bushing; 2 - electromagnetic coil; 3 and 4 - magnetically conductive disks; 5 - anchor; 6 - bushing
Safety couplings (Fig. 3.12) connect two shafts under normal operating conditions and break the kinematic chain when the load increases. Chain rupture can occur when a special element is destroyed, as well as as a result of slippage of mating and rubbing parts (for example, disks) or disengagement of the cams of two mating parts of the coupling.
A pin is usually used as a destructible element, the cross-sectional area of which is calculated to transmit a given torque. Disengagement of the mating elements of the coupling occurs provided that the axial force arising on the teeth, cams 1 or balls 5
, when overloaded, exceeds the force created by the springs 3 and adjusted by the nut 4. When displaced, the movable element 2 of the clutch acts on the limit switch, which breaks the electrical power supply circuit of the motor
drive.
Overrunning clutches (Fig. 3.13) are designed to transmit torque when the links of a kinematic chain rotate in a given direction and to disconnect the links when rotating in the opposite direction, as well as to transmit to the shaft different rotation frequencies (for example, slow - working rotation and fast - auxiliary ). The overrunning clutch allows you to transmit additional (fast) rotation without turning off the main chain. The most widely used in machine tools are roller type couplings, which can transmit torque in two directions.
Ratchet mechanisms are also used as overtaking clutches.
Rice. 3.12. Schemes of safety clutches: a - ball; b - cam; 1 - cams; 2 - movable element of the coupling; 3 - springs; 4 - nut; 5 - balls
Rice. 3.13. Overrunning roller clutch: 1 - clip; 2 - hub; 3 - rollers; 4 - drive fork; 5 - springs
3.3. Main and feed drives
A set of mechanisms with a source of motion, which serves to activate the executive body of a machine tool with specified characteristics of speed and accuracy, is called a drive.
Metal-cutting machines are equipped with an individual drive; On many machines, the main movement, feed movement, and auxiliary movements are carried out from separate sources - electric motors and hydraulic devices. The speed change can be stepless or stepwise.
Electric motors of direct and alternating current, hydraulic motors and pneumatic motors are used as drives for metal-cutting machines. Electric motors are the most widely used drives for machine tools. Where stepless control of the shaft speed is not required, asynchronous AC motors are used (as they are the cheapest and simplest). For stepless speed control, especially in feed mechanisms, DC electric motors with thyristor control are increasingly used.
The advantages of using an electric motor as a drive include: high rotation speed, the possibility of automatic and remote control, and the fact that their operation does not depend on the ambient temperature.
Among the transmissions of motion from the engine to the working parts of the machine, mechanical transmissions are most widespread. According to the method of transmitting motion from the driving element to the driven element, mechanical transmissions are divided as follows:
Friction transmissions with direct contact (friction) or with a flexible connection (belt);
Gear transmissions with direct contact (gear, worm, ratchet, cam) or with a flexible connection (chain).
Friction transmissions with a flexible connection include belt transmissions (Fig. 3.14). In these transmissions, the pulleys of the drive and driven shafts are covered by a belt with a certain tension force, which provides the friction force between the belt and the pulleys necessary to transmit force. The tension, limited by the strength of the belt, is adjusted by moving the shafts apart or using a special tensioning device.
Belts are made of leather, rubberized fabric, plastic, and they have different cross-sectional shapes. Belts with a flat section (Fig. 3.14, b) are used when transmitting high speeds (50 m/s and above) with relatively little effort. Large powers are transmitted by several V-belts (Fig. 3.14, c) or a poly-V-belt (Fig. 3.14, d). Transmissions with round belts (Fig. 3.14, e) are used for low relative forces and in transmissions between cross shafts. Belts with a poly-V-section are widely used (see Fig. 3.14, d) to increase the friction force (at the same tension as for flat belts).
In friction and belt drives, slipping always occurs between the rubbing surfaces, so the actual gear ratio for them is:
where is the theoretical gear ratio; - slip coefficient.
To prevent slipping, toothed belts are used (Fig. 3.14, e).
Rice. 3.14. Diagram of a belt drive (a) and transmission with a flat belt (b), V-belt (c), poly V-belt ( G), round belt (d), timing belt ( e): 1 - pulling metal cable of the toothed belt; 2 - toothed belt base made of plastic or rubber; 3 - pulley; - leading roller; and are the center of rotation and the diameter of the drive roller, respectively; - driven roller; and are the center of rotation and the diameter of the driven roller, respectively; - belt tension force; - distance between the centers of rotation of the driving and driven rollers
Chain transmissions (Fig. 3.15) (for lubrication and cooling systems), like transmission by toothed belts, more consistently transmit rotation speed to the driven shaft and can transmit greater power.
Rice. 3.15. Chain drive: - drive sprocket; - driven sprocket
Gear transmission (Fig. 3.16) is the most common transmission, as it provides high stability of rotation speeds, is capable of transmitting high powers and has relatively small overall dimensions. Gears are used to transmit rotation between shafts (parallel, intersecting, intersecting), as well as to convert rotational motion into translational motion (or vice versa). Movement from one shaft to another is transmitted as a result of the mutual engagement of gears forming a kinematic pair. The teeth of these wheels have a special shape. The most common gearing is one in which the profile of the teeth is outlined along a curve called the involute of a circle or simply the involute, and the gearing itself is called involute.
The drive with gearboxes is the most common drive for the main movement and feed movement in metal-cutting machines and is called a gearbox and a feedbox, respectively.
Speed boxes (Fig. 3.17) are distinguished by their layout and method of switching speeds. The layout of the gearbox is determined by the purpose of the machine and its standard size.
Gearboxes with replaceable wheels are used in machine tools with relatively rare drive settings. The box is characterized by simplicity of design and small overall dimensions.
Speed boxes with movable wheels (Fig. 3.17, a) are widely used mainly in universal manually operated machines.
Rice. 3.16. Types of gears for rotational movements: a and b - straight-cut cylindrical gear of external and internal gearing, respectively; c - helical cylindrical gear of external gearing; g - spur bevel gear; d - chevron wheel; e - worm gear
Rice. 3.17. Kinematic diagrams of gearboxes: a - with mobile wheels: - gears; b - with cam clutches: 0, I, II, III, IV - gearbox shafts; - gears; - electric motor; Mf1, Mf2, MfZ, Mf4 - friction clutches; - claw coupling
The disadvantages of these boxes are: the need to turn off the drive before changing gears; the possibility of an accident if the lock is broken and two gears of the same group are simultaneously engaged between adjacent shafts; relatively large dimensions in the axial direction.
Speedboxes with cam clutches (Fig. 3.17, b) are characterized by small axial movements of the clutches during switching, the possibility of using helical and chevron wheels, and low switching forces. The disadvantages include the need to turn off and slow down the drive when changing gears.
Gearboxes with friction clutches, unlike gearboxes with cam clutches, provide smooth gear changes on the go. In addition to the disadvantages inherent in boxes with claw couplings, they are also characterized by limited transmitted torque, large overall dimensions, reduced efficiency, etc. Despite this, boxes are used in machines of the turning, drilling and milling groups.
Gearboxes with electromagnetic and other clutches that allow the use of remote control are used in various automatic and semi-automatic machines, including CNC machines. To unify the drive of the main movement of such machines, the domestic machine tool industry produces unified automatic gearboxes (AKS) in seven overall sizes, designed for a power of 1.5...55 kW; number of speed steps - 4... 18.
Depending on the type of gear mechanisms used to adjust the feeds, the following feed boxes are distinguished:
With replaceable wheels at a constant distance between the shaft axes;
With movable wheel blocks;
With built-in stepped wheel cones (sets) and draw keys;
Norton (with ring gear);
With guitars of interchangeable wheels.
To obtain feed boxes with specified characteristics, they are often designed using several of the listed mechanisms simultaneously.
Norton boxes are used in feed drives of screw-cutting machines due to the possibility of accurately implementing specified gear ratios. The advantages of boxes of this type are a small number of gears (the number of wheels is two more than the number of gears), the disadvantages are low rigidity and accuracy of mating of the engaged wheels, the possibility of clogging of gears if there are cutout in the box body.
Feed boxes with replacement wheels (Fig. 3.18) make it possible to adjust the feed with any degree of accuracy. The features of guitars with interchangeable wheels make them convenient for use in various types of machines, especially in machines for serial and mass production. Such machines are equipped with appropriate sets of replacement wheels.
Rice. 3.18. Kinematic diagram (a) and design (b and c) of the guitar of replaceable gears: 1 - rocker; 2 - nut; 3 - screw; K, L, M, N - gears
3.4. General information about the technological process
machining
The process of creating material wealth is called production.
The part of the production process that contains targeted actions to change and (or) determine the state of the object of labor is called the technological process. The technological process can be related to the product, its component part, or to methods of processing, shaping and assembly. Objects of labor include blanks and products. Depending on the execution method, the following elements of technological processes are distinguished:
Shaping (casting, molding, electroforming);
Processing (cutting, pressure, thermal, electrophysical, electrochemical, coating);
Assembly (welding, soldering, gluing, sub-assembly and general assembly);
Technical control.
The completed part of the technological process, performed at one workplace, is called a technological operation. The definition of these terms is given in GOST 3.1109-82.
In production, a worker most often has to deal with the following types of descriptions of technological processes in terms of their level of detail:
A route description of a technological process is an abbreviated description of all technological operations in the route map in the sequence of their execution, without indicating transitions and technological modes;
Operational description of the technological process, a complete description of all technological operations in the sequence of their execution, indicating transitions and technological modes;
An abbreviated description of technological operations in a route map in the sequence of their execution, with a full description of individual operations in other technological documents, is called a route-operational description of the process.
The description of manufacturing operations in their technological sequence is given in compliance with the rules for recording these operations and their coding. For example, cutting operations performed on metal-cutting machines are divided into groups. Each group is assigned specific numbers: 08 - program (operations on computer-controlled machines); 12 - drilling; 14 - turning; 16 - grinding, etc.
When recording the content of operations, the established names of technological transitions and their conventional codes are used, for example: 05 - bring; 08 - sharpen; 18 - polish; 19 - grind; 30 - sharpen; 33 - grind; 36 - milling; 81 - secure; 82 - configure; 83 - reinstall; 90 - remove; 91 - install.
The part of the technological operation carried out with constant fixation of the workpieces being processed is called at camp The fixed position occupied by a workpiece permanently fixed in a fixture relative to a tool or a stationary piece of equipment for performing a certain part of the operation is called position.
The main elements of a technological operation include transitions. A technological transition is a completed part of a technological operation, performed by the same means of technological equipment under constant technological conditions and installation. An auxiliary transition is a completed part of a technological operation, consisting of human and (or) equipment actions that are not accompanied by a change in the properties of the object of labor, but are necessary to complete the technological transition.
When registering technological processes, a set of technological documentation is created - a set of sets of technological process documents and individual documents necessary and sufficient to carry out technological processes in the manufacture of a product or its components.
The Unified System of Technological Documentation (UTDS) provides the following documents: route map, sketch map, operational map, equipment list, materials list, etc. Description of the content of technological operations, i.e. a description of the route technological process is given in a route map - the main technological document in the conditions of single and pilot production, with the help of which the technological process is brought to the workplace. In the route map, in accordance with established forms, data on equipment, accessories, material and labor costs are indicated. The operational technological process is presented in operational cards compiled together with sketch cards.
A technological document can be graphic or text. It separately or in combination with other documents defines the technological process or operation of manufacturing a product. A graphic document, which, by its purpose and content, replaces a working drawing of a part in a given operation, is called an operational sketch. The main projection on the operational sketch depicts the view of the workpiece from the side of the workplace at the machine after the operation has been completed. The machined surfaces of the workpiece in the operational sketch are shown as a solid line, the thickness of which is two to three times greater than the thickness of the main lines in the sketch. The operational sketch indicates the dimensions of the surfaces processed in this operation and their position relative to the bases. You can also provide reference data indicating “dimensions for reference”. The operational sketch indicates the maximum deviations in the form of numbers or symbols of tolerance and fit fields in accordance with the standards, as well as the roughness of the processed surfaces that must be ensured by this operation.
The rules for recording operations and transitions, encoding them and filling out cards with data are determined by the standards and methodological materials of the parent organization for the development of the UST.
Security questions
1. Give formulas for determining the cutting speed during the main rotational motion.
2. How are the gear ratios of kinematic pairs of machine tools found?
3. What is the regulation range?
4. What are the requirements for machine beds and guides?
5. Tell us about the purpose and designs of spindle units and bearings.
6. What couplings are used in machine tools?
7. Define a drive and tell us about the drives used in machine tools.
8. What basic elements of machine tool drives do you know?
9. Tell us about the types and designs of gearboxes.
10.What designs of feed boxes are used in machine tools?
11.What is called a technological process? Name the components of technological processes.
When the drawings do not need to show the design of the product and individual parts, but it is enough to show only the principle of operation, the transmission of motion (kinematics of a machine or mechanism), diagrams are used.
Scheme called a design document on which the component parts of the product, their relative position and connections between them are shown in the form of symbols.
A diagram, like a drawing, is a graphic image. The difference is that in the diagrams the details are depicted using conventional graphic symbols. These designations are greatly simplified images, resembling details only in general terms. In addition, the diagrams do not show all the parts that make up the product. Only those elements that are involved in transmitting the movement of liquid, gas, etc. are shown.
Kinematic schemes
Symbols for kinematic diagrams are established by GOST 2.770–68, the most common of them are given in table. 10.1.
Table 10.1
Conventional graphic symbols for kinematic diagrams
|
Name |
Visual representation |
Symbol |
|
Shaft, axle, platen, rod, connecting rod, etc. |
||
|
Sliding and rolling bearings on the shaft (without specifying the type): A– radial b– persistent one-sided |
||
|
Connecting the part to the shaft: A– free when rotating b– movable without rotation V– deaf |
||
|
Shaft connection: A– deaf b– articulated |
||
|
Clutches: A– cam one-sided b – cam double-sided V– friction double-sided (without specifying type) |
||
|
Step pulley mounted on a shaft |
||
|
Open flat belt transmission |
||
|
Chain transmission (without specifying the type of chain) |
||
|
Gear transmissions (cylindrical): A b–c straight in – with oblique teeth |
||
|
Gear transmissions with intersecting shafts (bevel): A– general designation (without specifying the type of teeth) b–c straight in – with spiral g – s circular teeth |
||
|
Rack and pinion transmission (without specifying the type of teeth) |
||
|
Screw transmitting movement |
||
|
Nut on the screw transmitting the movement: A - one-piece b – detachable |
||
|
Electric motor |
||
|
A - compression b – sprains V - conical |
As can be seen from the table, the shaft, axis, rod, connecting rod are indicated by a solid thick straight line. The screw that transmits the movement is indicated by a wavy line. Gear wheels are designated by a circle drawn by a dash-dot line on one projection, and in the form of a rectangle surrounded by a solid line on the other. In this case, as in some other cases (chain transmission, rack and pinion transmissions, friction clutches, etc.), general designations (without specifying the type) and specific designations (indicating the type) are used. On a general designation, for example, the type of gear teeth is not shown at all, but on specific designations they are shown with thin lines. Compression and extension springs are indicated by a zigzag line. There are also symbols to depict the connection between the part and the shaft.
Conventional signs used in diagrams are drawn without adhering to the scale of the image. However, the ratio of the sizes of the conventional graphic symbols of interacting elements should approximately correspond to their actual ratio.
When repeating the same signs, you need to make them the same size.
When depicting shafts, axles, rods, connecting rods and other parts, use solid lines of thickness s. Bearings, gears, pulleys, couplings, motors are outlined with lines approximately twice as thin. A thin line draws axes, circles of gears, keys, and chains.
When performing kinematic diagrams, inscriptions are made. For gears, the module and number of teeth are indicated. For pulleys, record their diameters and widths. The power of the electric motor and its speed are also indicated by the type inscription N= 3.7 kW, n= 1440 rpm.
Each kinematic element shown in the diagram is assigned a serial number, starting from the engine. The shafts are numbered with Roman numerals, the remaining elements are numbered with Arabic numerals.
The serial number of the element is placed on the shelf of the leader line. Under the shelf indicate the main characteristics and parameters of the kinematic element.
If the diagram is complex, then the position number is indicated for the gear wheels, and the specification of the wheels is attached to the diagram.
When reading and drawing up diagrams of products with gears, you should take into account the features of the image of such gears. All gears, when depicted as circles, are conventionally considered transparent, assuming that they do not cover the objects behind them. An example of such an image is shown in Fig. 10.1, where in the main view the circles depict an engagement of two pairs of gears. From this view it is impossible to determine which gears are in front and which are behind. This can be determined using the view on the left, which shows that a pair of wheels 1 – 2 is in front, and a couple 3 – 4 is located behind it.
Rice.10.1.
Another feature of the image of gear wheels is the use of so-called expanded images. In Fig. 10.2, two types of gearing schemes are made: undeveloped (a) and expanded ( b).
Rice. 10.2.
The arrangement of the wheels is such that in the left view the wheel 2 covers part of the wheel 1, As a result, there may be ambiguity when reading the diagram. To avoid errors, you can do as in Fig. 10 .2 , b, where the main view is preserved, as in Fig. 10.2, A, and the view on the left is shown in an expanded position. In this case, the shafts on which the gears are located are located from each other at a distance of the sum of the radii of the wheels.
In Fig. 10.3, b An example of a kinematic diagram of a lathe's gearbox is given, and in Fig. 10.3, A A visual representation of it is given.
It is recommended to start reading kinematic diagrams by studying the technical passport, which will help you become familiar with the structure of the mechanism. Then they proceed to read the diagram, looking for the main parts, using their symbols, some of which are given in table. 10.1. Reading the kinematic diagram should start from the engine, which gives movement to all the main parts of the mechanism, and proceed sequentially along the transmission of motion.
GOST 2.770-68*. ESKD. Conventional graphic symbols in diagrams. Elements of kinematics. Kinematic diagrams symbols
$direct1|
Name |
Designation |
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3, 4. (Excluded, Amendment No. 1) |
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5. Connection of link parts |
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a) motionless |
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d), e) (Excluded, Amendment No. 1) |
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6. Kinematic pair a) rotational |
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c) progressive |
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| d) screw |
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e) cylindrical |
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e) spherical with a finger |
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g) cardan joint |
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h) spherical (ball) |
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i) planar |
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j) tubular (ball-cylinder) |
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l) point (ball-plane) |
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a) radial |
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b) (Deleted, Amendment No. 1) |
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c) persistent |
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8. Sleeve bearings: |
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a) radial |
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b) (Deleted, Amendment No. 1) |
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bilateral |
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d) persistent: |
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unilateral |
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bilateral |
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9. Rolling bearings: |
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a) radial |
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e) radial contact: |
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unilateral |
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bilateral |
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e) (Deleted, Amendment No. 1) |
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g) persistent: |
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unilateral |
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bilateral |
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h) (Deleted, Amendment No. 1) |
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a) deaf |
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b) (Deleted, Amendment No. 1) |
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c) elastic |
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d) compensating |
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a) general designation |
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b) one-sided |
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c) bilateral |
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a) general designation |
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c) centrifugal friction |
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d) safety |
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with destructible element |
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with an indestructible element |
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16. Flat cams: |
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a) longitudinal movement |
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b) rotating |
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c) rotating slotted |
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17. Drum cams: |
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a) cylindrical |
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b) conical |
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c) curvilinear |
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a) pointed |
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b) arc |
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c) roller |
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d) flat |
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b) eccentric |
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c) slider |
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d) backstage |
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Notes: |
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d) with rack and pinion gear |
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a) with external gearing |
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b) with internal gearing |
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c) general designation |
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26. Friction gears: |
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b) with tapered rollers |
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27. Flywheel on shaft |
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30. Flat belt transmission |
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32. Round belt transmission |
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33. Toothed belt transmission |
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34. Chain transmission: |
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b) round link |
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c) lamellar |
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d) toothed |
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c) internal gearing |
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d) with non-round wheels |
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35a. Gear transmissions with flexible wheels (wave) 41. Springs: 42. Shift lever |
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43. End of the shaft for a removable handle |
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44. (Deleted, Amendment No. 1) |
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45. Handle |
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46. Handwheel |
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47. Movable stops |
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48. (Deleted, Amendment No. 1) |
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49. Flexible shaft for transmitting torque |
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50. (Deleted, Amendment No. 1) |
snipov.net
3 Kinematic diagrams of machines and symbols of their elements
Kinematic diagram of the machine - an image using symbols (Table 1.2) of the relationship of individual elements and mechanisms, machines involved in the transmission of movements to various organs.
Table 1.2 – Graphic symbols for kinematic diagrams GOST 2.770-68
Kinematic diagrams are drawn on an arbitrary scale. However, one should strive to fit the kinematic diagram into the contours of the main projection of the machine or its most important assembly units, ensuring that their relative position is preserved.
For machines that, in addition to mechanical transmissions, have hydraulic, pneumatic and electrical devices, hydraulic, pneumatic, electrical and other circuits are also drawn up.
4 Determination of gear ratios and movements in various types of gears
The ratio of the rotational speed (angular velocity) n2 of the driven shaft to the rotational speed n1 of the drive shaft is called the gear ratio:
Belting. Gear ratio without taking into account belt sliding (Figure 1.1, a)
i = n2/ n1 = d1 / d2,
where d1 and d2 are the diameters of the driving and driven pulleys, respectively.
Belt slip is taken into account by introducing a correction factor equal to 0.97-0.985.
Chain transmission. Gear ratio (Figure 1.1, b)
i = n2 / n1 = z1 / z2,
where z1 and z2 are the numbers of teeth of the driving and driven sprockets, respectively.
Gear transmission (Figure 1.1, c), carried out by cylindrical or bevel gears. Gear ratio
i = n2 / n1 = z1 / z2,
where z1 and z2 are the numbers of teeth of the driving and driven gears, respectively.
Worm gear. Gear ratio (Figure 1.1, d)
i = n2 / n1 = z / zк,
where Z is the number of worm passes; zk is the number of teeth of the worm wheel.
Rack and pinion transmission. Length of linear movement of the rack per one revolution of the rack and pinion gear (Figure 1.1, d)
where p = m - rack tooth pitch, mm; z is the number of teeth of the rack and pinion gear; m - module of the rack and pinion gear teeth, mm.
Screw and nut. Moving the nut per revolution of the screw (Figure 1.1, e)
where Z is the number of screw passes; pv - propeller pitch, mm.
5 TRANSMISSION RATIO OF KINEMATIC CHAINS. CALCULATION OF ROTATION SPEED AND TORQUES
To determine the overall gear ratio of the kinematic chain (Figure 1.1, g), it is necessary to multiply the gear ratios of the individual gears included in this kinematic chain:
The rotation speed of the last driven shaft is equal to the rotation speed of the drive shaft multiplied by the total gear ratio of the kinematic chain:
n = 950 i total,
i.e. n = 950 59.4 min-1.
The torque on the Mshp spindle depends on the gear ratio of the kinematic chain from the electric motor to the spindle. If the electric motor develops torque Mdv, then
Мшп = Мдв/ i total
where i total is the gear ratio of the kinematic chain from the electric motor to the spindle; - efficiency of the kinematic chain from the electric motor to the spindle.
studfiles.net
| Name | Designation | ||
| Shaft, platen, axle, rod, connecting rod |  |
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| Fixed link (stand). Note. To indicate the immobility of any link, part of its outline is covered with shading |
 |
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| Name | Designation | ||
| Connection of link parts: | |||
| motionless |  |
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| fixed, adjustable | |||
| fixed connection of a part with a shaft, rod |  |
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| Kinematic pair: | |||
| rotational |  |
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| rotational multiple, for example, double |  |
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| progressive |   |
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| screw |  |
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| cylindrical | |||
| spherical with finger | |||
| universal joint | |||
| spherical (ball) | |||
| planar |  |
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| tubular (ball-cylinder) |  |
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| point (ball-plane) |  |
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| Sliding and rolling bearings on the shaft (without specifying the type): | |||
| radial | |||
| persistent |  |
||
| Plain bearings: | |||
| radial | |||
| Name | Designation | ||
| persistent one-sided | |||
| persistent double-sided | |||
| Rolling bearings: | |||
| radial | |||
| angular contact one-sided | |||
| angular contact double-sided | |||
| persistent one-sided |  |
||
| persistent double-sided |  |
||
| Clutch. General designation without specification of type | |||
| Non-disengaging clutch (uncontrolled) | |||
| deaf | |||
| elastic | |||
| compensating | |||
| Coupled coupling (controlled) | |||
| general designation | |||
| one-sided | |||
| bilateral | |||
| Coupled mechanical clutch | |||
| synchronous, for example, gear | |||
| asynchronous, for example, friction | |||
| Electric coupling | |||
| Coupling hydraulic or pneumatic | |||
| Automatic clutch (self-acting) | |||
| general designation | |||
| overtaking (freewheel) | |||
| centrifugal friction | |||
| safety with destructible element | |||
| Name | Designation | ||
| safety with indestructible element | |||
| Brake. General designation without specification of type | |||
| Flat jaws: | |||
| longitudinal movement |  |
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| rotating |  |
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| rotating slotted | |||
| Drum cams: | |||
| cylindrical |  |
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| conical |  |
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| curvilinear |  |
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| Pusher (driven link) | |||
| pointed |  |
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| arc |  |
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| roller |  |
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| flat |  |
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| Two-element linkage linkage | |||
| crank, rocker arm, connecting rod |  |
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| eccentric |  |
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| slider |   |
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| Name | Designation | ||
| backstage |  |
||
| Three-element linkage of lever mechanisms Notes: 1. Hatching may not be applied. 2. The designation of a multi-element link is similar to two- and three-element |  |
||
| Ratchet gears: | |||
| external gear single-sided |  |
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| external gear double sided |  |
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| with internal gearing single-sided |  |
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| rack and pinion |  |
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| Maltese mechanisms with a radial arrangement of grooves at the Maltese cross: | |||
| external gear |  |
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| internal gear |  |
||
| general designation |  |
||
| Name | Designation | ||
| Friction gears: | |||
| with cylindrical rollers |  |
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| with tapered rollers |  |
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| with tapered rollers adjustable |  |
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| with curved generatrices of working bodies and tilting rollers, adjustable |  |
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| end (frontal) adjustable |  |
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| with spherical and conical (cylindrical) rollers, adjustable |  |
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| Name | Designation | ||
| with cylindrical rollers, converting rotational motion into translational |  |
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| with hyperboloid rollers that convert rotational motion into helical motion |  |
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| with flexible rollers (wave) |  |
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| Flywheel on shaft | |||
| Step pulley mounted on a shaft |  |
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| Belt transmission: | |||
| without specifying the type of belt | |||
| flat belt |  |
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| V-belt |  |
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| round belt |  |
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| toothed belt | |||
| Chain transmission: | |||
| general designation without specifying the type of chain |  |
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| round link |  |
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| Name | Designation | ||
| lamellar |  |
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| gear |  |
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| Gear transmissions (cylindrical): | |||
| external gearing (general designation without specifying the type of teeth) |  |
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| the same, with straight, oblique and chevron teeth |  |
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| internal gearing |  |
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| with non-round wheels |  |
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| Gear transmissions with flexible wheels (wave) |  |
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| Gear transmissions with intersecting shafts and bevel gears: | |||
  |
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| Name | Designations | ||
| with straight, spiral and circular teeth |  |
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| Gear transmissions with crossed shafts: | |||
| hypoid |   |
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| worm with cylindrical worm |  |
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| worm globoid |  |
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| Rack and pinion transmissions: | |||
| general designation without specifying the type of teeth |  |
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| Transmission by gear sector without specifying the type of teeth |  |
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| Screw transmitting movement |  |
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| Nut on the screw transmitting the movement: | |||
| one-piece |  |
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| one-piece with balls |  |
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| Name | Designation | ||
| detachable |  |
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| Springs: | |||
| cylindrical compression |  |
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| cylindrical tension |  |
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| conical compression |  |
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| cylindrical, torsional |  |
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| spiral |  |
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| leafy: | |||
| Single |  |
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| Spring | |||
| disc-shaped |  |
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| Shift lever |  |
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| The end of the shaft for a removable handle |  |
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| Lever |  |
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| Handwheel |  |
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| Mobile stops |  |
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| Flexible shaft for transmitting torque |  |
poznayka.org
|
Name |
Designation |
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1. Shaft, platen, axle, rod, connecting rod, etc. |
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2. Fixed link (stand). To indicate the immobility of any link, part of its outline is covered with shading, for example, |
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3, 4. (Excluded, Amendment No. 1) |
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5. Connection of link parts |
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a) motionless |
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b) fixed, adjustable |
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c) fixed connection of a part with a shaft, rod |
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d), e) (Excluded, Amendment No. 1) |
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6. Kinematic pair a) rotational |
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b) rotational multiple, for example, double |
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c) progressive |
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d) screw |
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e) cylindrical |
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e) spherical with a finger |
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g) cardan joint |
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h) spherical (ball) |
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i) planar |
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j) tubular (ball-cylinder) |
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l) point (ball-plane) |
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7. Sliding and rolling bearings on the shaft (without specifying the type): |
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a) radial |
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b) (Deleted, Amendment No. 1) |
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c) persistent |
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8. Sleeve bearings: |
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a) radial |
|
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b) (Deleted, Amendment No. 1) |
|
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c) radial contact: one-sided |
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bilateral |
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d) persistent: |
|
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unilateral |
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bilateral |
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9. Rolling bearings: |
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a) radial |
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b), c), d) (Excluded, Amendment No. 1) |
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e) radial contact: |
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unilateral |
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bilateral |
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e) (Deleted, Amendment No. 1) |
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g) persistent: |
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unilateral |
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bilateral |
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h) (Deleted, Amendment No. 1) |
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10. Clutch. General designation without specification of type |
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11. Non-disengaging clutch (uncontrolled) |
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a) deaf |
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b) (Deleted, Amendment No. 1) |
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c) elastic |
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d) compensating |
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d), f), g), h) (Excluded, Amendment No. 1) |
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12. Coupled clutch (controlled) |
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a) general designation |
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b) one-sided |
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c) bilateral |
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13. Mechanical clutch |
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a) synchronous, for example, gear |
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b) asynchronous, for example, friction |
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c) - o) (Excluded, Amendment No. 1) |
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13a. Electric coupling |
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13b. Coupling hydraulic or pneumatic |
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14. Automatic clutch (self-acting) |
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a) general designation |
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b) overtaking (freewheel) |
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c) centrifugal friction |
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d) safety |
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with destructible element |
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with an indestructible element |
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15. Brake. General designation without specification of type |
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16. Flat cams: |
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a) longitudinal movement |
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b) rotating |
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c) rotating slotted |
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17. Drum cams: |
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a) cylindrical |
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b) conical |
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c) curvilinear |
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18. Pusher (driven link) |
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a) pointed |
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b) arc |
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c) roller |
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d) flat |
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19. Two-element linkage of lever mechanisms |
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a) crank, rocker arm, connecting rod |
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b) eccentric |
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c) slider |
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d) backstage |
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20. Three-element linkage of lever mechanisms |
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Notes: |
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1. Hatching may not be applied. |
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2. The designation of a multi-element link is similar to two- and three-element |
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21, 22, 23 (Excluded, Amendment No. 1) |
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24. Ratchet gears: |
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a) with external gearing, single-sided |
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b) with external gearing, double-sided |
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c) with internal gearing, one-sided |
|
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d) with rack and pinion gear |
|
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25. Maltese mechanisms with a radial arrangement of grooves at the Maltese cross: |
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a) with external gearing |
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b) with internal gearing |
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c) general designation |
|
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26. Friction gears: |
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a) with cylindrical rollers |
|
|
b) with tapered rollers |
|
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c) with tapered rollers, adjustable |
|
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d) with curved generatrices of working bodies and tilting rollers, adjustable |
|
|
e) end (frontal) adjustable |
|
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e) with spherical and conical (cylindrical) rollers, adjustable |
|
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g) with cylindrical rollers, converting rotational motion into translational |
|
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h) with hyperboloid rollers that convert rotational motion into screw motion |
|
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i) with flexible rollers (wave) |
|
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27. Flywheel on shaft |
|
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28. Step pulley mounted on a shaft |
|
|
29. Transmission by belt without specifying the type of belt |
|
|
30. Flat belt transmission |
|
|
31. V-belt transmission |
|
|
32. Round belt transmission |
|
|
33. Toothed belt transmission |
|
|
34. Chain transmission: |
|
|
a) general designation without specifying the type of circuit |
|
|
b) round link |
|
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c) lamellar |
|
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d) toothed |
|
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35. Gear transmissions (cylindrical): |
|
|
a) external gearing (general designation without specifying the type of teeth) |
|
|
b) the same, with straight, oblique and chevron teeth |
|
|
c) internal gearing |
|
|
d) with non-round wheels |
|
|
35a. Gear transmissions with flexible wheels (wave) 41. Springs: 42. Shift lever Topic 1.1. Kinematic schemes When the drawings do not need to show the design of the product and individual parts, but it is enough to show only the principle of operation of the product, the transmission of motion (kinematics of a machine or mechanism), diagrams are used. A diagram is a design document on which the component parts of the product, their relative positions and connections between them are shown as symbols. A diagram, like a drawing, is a graphic image. The difference is that in the diagrams the details are depicted using conventional graphic symbols. These designations are greatly simplified images, resembling details only in general terms. In addition, the diagrams do not show all the parts that make up the product. Only those elements that are involved in transmitting the movement of liquid, gas, etc. are shown. Kinematic schemes Symbols for kinematic diagrams are established by GOST 2.770-68, the most common of them are given in Table 1. As can be seen from the table, the shaft, axis, rod, connecting rod are indicated by a thick thick straight line (item 1). The screw transmitting the movement is indicated by a wavy line (item 12). Gear wheels are designated by a circle drawn by a dash-dot line on one projection, and in the form of a rectangle surrounded by a solid line on the other (clause 9). In this case, as in some other cases (chain transmission, rack and pinion transmissions, friction clutches, etc.), general designations (without specifying the type) and specific designations (indicating the type) are used. On the general designation, for example, the type of gear teeth is not shown at all (item 9, a), but on specific designations they are shown with thin lines (item 9, b, c). Compression and extension springs are indicated by a zigzag line (item 15). There are also symbols to depict the connection between the part and the shaft. A connection free for rotation is shown in paragraph 3,a, a movable connection without rotation is shown in paragraph 3,6, a blind connection (with a cross) is shown in paragraph 3,e; 7; 8, etc. Conventional signs used in diagrams are drawn without adhering to the scale of the image. However, the ratio of the sizes of the conventional graphic symbols of interacting elements should approximately correspond to the actual ratio of their sizes. When repeating the same signs, you need to make them the same size. When depicting shafts, axles, rods, connecting rods and other parts, solid lines of thickness s are used. Bearings, gears, pulleys, couplings, motors are outlined with lines approximately twice as thin. A thin line draws axes, circles of gears, keys, and chains. When performing kinematic diagrams, inscriptions are made. For gears, the module and number of teeth are indicated. For pulleys, record their diameters and widths. The power of the electric motor and its rotational speed are also indicated by the type inscription N = 3.7 kW, n = 1440 rpm. Each kinematic element shown in the diagram is assigned a serial number, starting from the engine. The shafts are numbered with Roman numerals, the remaining elements are numbered with Arabic numerals. The serial number of the element is placed on the shelf of the leader line. Under the shelf indicate the main characteristics and parameters of the kinematic element. If the diagram is complex, then the position number is indicated for the gear wheels, and the specification of the wheels is attached to the diagram. Table 1 Conventional graphic symbols for kinematic diagrams When reading and drawing up diagrams of products with gears, you should take into account the features of the image of such gears. All gears, when depicted as circles, are conventionally considered transparent, assuming that they do not cover the objects behind them. An example of such an image is shown in Fig. 1, where in the main view the circles depict an engagement of two pairs of gears. Rice. 1 GEAR DIAGRAM From this view it is impossible to determine which gears are in front and which are behind. This can be determined using the view on the left, which shows that pair of wheels 1-2 is in front, and pair 3-4 is located behind it. Another feature of the image of gears is the use of so-called expanded images. In Fig. 2, two types of gearing diagrams are made. The arrangement of the wheels is such that in the left view, wheel 2 overlaps part of wheel 1, as a result of which confusion may arise when reading the diagram. To avoid errors, it is allowed to proceed as in Fig. 2, b, where the main view is preserved as in Fig. 2, a, and the view on the left is shown in an expanded position. Rice. 2 EXPANDED AND UNEXPANDED IMAGES OF THE GEAR TRANSMISSION IN THE DIAGRAM In this case, the shafts on which the gears are located are located from each other at a distance of the sum of the radii of the wheels. Figure 3, b shows an example of a lathe gearbox diagram, and Figure 3, a shows its axonometric image. Rice. 3 (a) AXONOMETRIC IMAGE OF A LATHE SPEED BOX It is recommended to start reading kinematic diagrams by studying the technical passport, which will help you become familiar with the structure of the mechanism. Then they proceed to read the diagram, looking for the main parts, using their symbols, some of which are given in table. 1. Reading the kinematic diagram should start from the engine, which gives movement to all the main parts of the mechanism, and proceed sequentially to the transmission of motion. megalektsii.ru 3.3. Positional designations of elementsKinematic diagrams establish the composition of mechanisms and explain the conditions for the interaction of their elements. Kinematic diagrams are performed in the form of a sweep: all shafts and axes are conventionally considered to be located in the same plane or in parallel planes. The relative position of the elements on the kinematic diagram must correspond to the initial, average or working position of the executive bodies of the product (mechanism). It is allowed to explain with an inscription the position of the executive bodies for which the diagram is shown. If an element changes its position during operation of the product, then the diagram may show its extreme positions with thin dash-dotted lines. In the kinematic diagram, the elements are assigned numbers in the order of motion transmission. The shafts are numbered with Roman numerals, the remaining elements are numbered with Arabic numerals. The serial number of the element is indicated on the shelf of the leader line drawn from it. Under the shelf, leader lines indicate the main characteristics and parameters of the kinematic element (type and characteristics of the engine, diameters of the belt pulleys, module and number of teeth of the gear, etc.) (Fig. 1). 3.4. List of elements Kinematic diagrams depict: shafts, axles, rods, connecting rods, cranks with solid main lines of thickness s; elements (gears, worms, sprockets, connecting rods, cams), shown in simplified external outlines - solid lines of thickness s/2; the outline of the product into which the diagram is inscribed - with solid thin lines, thickness s/3. Kinematic connections between the conjugate links of the pair, drawn separately, are shown by dashed lines of thickness s/2. Each element shown in the diagram is provided with a digital or alphanumeric designation. These designations are entered into the list of elements, which is made in the form of a table located above the main inscription and filled out from top to bottom according to the form (Fig. 2). The kinematic diagram begins to be read from the engine, which is turned on by the source of movement of all parts of the mechanism. By identifying each element of the kinematic chain shown in the diagram using the symbols, its purpose and the nature of the transmission of motion to the associated element are established. Rice. 2. Example of filling out the main inscription and additional columns The list of elements in the form of an independent document is issued on A4 sheets, the main inscription for text documents is carried out in accordance with GOST 2.104-68 (form 2 - for the first sheet and 2a - for subsequent ones). In column 1 of the main inscription (see Fig. 2) the name of the product is indicated, and under it, in a font one number smaller, the “List of elements” is written. The code for the list of elements must consist of the letter “P” and the code of the circuit for which the list is issued, for example, the code for the list of elements for the kinematic circuit diagram - PK3. 4. Kinematic schemes4.1. Structural diagramsThe block diagram shows all the main functional parts of the product (elements, devices and functional groups) and the main relationships between them. Functional parts are shown in the form of rectangles or graphic symbols. The construction of a diagram should give the most visual representation of the sequence of interaction of functional parts in the product. On the interconnection lines, it is recommended to use arrows to indicate the direction of the processes occurring in the product. When depicting functional parts in the form of rectangles, it is recommended to write names, types and designations inside the rectangles. If there are a large number of functional parts, it is allowed, instead of names, types and designations, to put serial numbers to the right of the image or above it, as a rule, from top to bottom in the direction from left to right. In this case, names, types and designations are indicated in a table placed on the diagram field. It is allowed to place explanatory inscriptions, diagrams or tables on the diagram that determine the sequence of processes in time, as well as indicate parameters at characteristic points (currents, voltages, mathematical dependencies, etc.). studfiles.net Types of kinematic schemes. Conventions for kinematic diagrams (according to GOST 3462-46)Symbols according to this standard are intended for kinematic diagrams in orthogonal projections.
Symbols on diagrams of parts of pipelines, fittings, heating and sanitary appliances and equipment (according to GOST 3463-46)
1. The angle must be indicated by the number of degrees. 2. Continuous filling with ink is allowed. 3. The Storz nut is identified by the inscription Storz. 4. The direction of movement is indicated by an arrow. 5. Inside the rectangle there can be two numbers separated by a fractional line, of which the upper one indicates the number of sections, the lower one indicates the section number. 6. Numbers characterizing the device may be placed above the designation. 7. The type of device can be indicated by a corresponding index, for example, MB manoevacuum gauge. 8. The liquid or gas being measured can be designated by the corresponding index.
Symbols of pipelines carrying liquids and gases (according to GOST 3464-46)
3. Each sheet of the drawing must contain explanations of the symbols used. 4. For a more detailed division of pipelines according to their contents (for example, clean water, warm water, etc.), the symbol is marked with a number (or letter) on the callout or on the pipeline line (Fig. 484, a) in compliance with the instructions in paragraph. 3. In these cases, and in general when there are a large number of pipelines, their designation of the same type is allowed with straight lines with numbers (or letters) in breaks (Fig. 484, b) in compliance with the instructions of paragraph 3. 5. If, according to scale conditions, the pipeline is shown not with one line, but with two parallel lines (as a longitudinal section), then the outermost generatrices of the pipe cylinder can be drawn in the form of solid black lines in pencil or ink, with the field between them painted in the corresponding color, with fittings and shaped parts can also be painted over completely.
6. When depicting pipelines in the form of single colored lines, symbols of fittings and fittings can be shown in the color of the pipe itself or in black.
7. If in a project or installation drawing any pipeline content (liquid or gas) is predominant for a given project or installation, then solid black lines should be used to designate such pipelines with a special reservation about this. 8. Pipeline symbols in this drawing must be of the same thickness. |
Designers developing various machines and mechanisms often perform kinematic diagrams. In doing so, they are guided by the standards and requirements set out in such a fundamental document as GOST 2.770–68.
| Designation | Name |
| Shaft, axle, rod, etc. | |
| Radial sliding and rolling bearings on the shaft | |
| Thrust bearings on the shaft | |
| Radial plain bearings | |
| Radial rolling bearings | |
| Angular contact rolling bearings | |
| coupling | |
| Elastic coupling | |
| Clutch (controlled) | |
| Brake | |
| Flywheel on shaft | |
 |
External gear ratchet mechanism |
 |
Belt transmission |
 |
Chain transmission |
 |
Cylindrical compression springs |
 |
Cylindrical tension springs |
 |
Cylindrical gear transmissions with external gearing |
 |
Cylindrical gear transmissions with internal gearing |
 |
Bevel gear transmissions with intersecting shafts |
 |
Gears with a cylindrical worm |
 |
Rack and pinion transmissions |
| Drum cams, cylindrical | |
| Rotating cams |
In technology, a diagram is understood as a graphic image that shows the component parts of a product, their design features, as well as the connections between them using simplified notations and symbols. As part of design documentation packages, diagrams play a fairly important role. They are present both in general descriptions of products, instructions for their installation, commissioning and operation. Schematic drawings provide invaluable assistance to personnel involved in installation, commissioning, and repair of machines, mechanisms and individual units. The diagrams make it possible to quickly understand what functional connections exist between mechanical, hydraulic, electrical and other links and systems of technical devices.
When the development of a machine just begins, designers draw a general sketch of the future product by hand, that is, they draw up its initial diagram. It conventionally displays all the main nodes, and also shows the relationships between them. Only after the schematic diagram of the device has been worked out, the development of drawings and other design documentation begins.
In modern mechanical engineering, the greatest use is found in those machines in which the transmission of motion is based on a mechanical, hydraulic or electrical operating principle.
Kinematic schemesPurpose kinematic schemes is a reflection of the connection between the working mechanism and the drive. It should be noted that in modern cars, machine tools and other technological equipment, mechanical transmissions are very complex and contain many elements. Therefore, in order to correctly create diagrams of such structures, you need to be well aware of all the conventions that are used to graphically depict the operating principle of a machine or mechanism without specifying their design features. For example, kinematic diagrams of machine equipment reflect exactly how the rotational movement of the electric motor shaft is communicated to the spindle, and the outline of the machine is shown (or not shown) as a thin line.
If non-standardized symbols are used in the diagrams, they require explanation. As for the external outlines and schematic sections, they are depicted in the diagrams in a simplified manner, in accordance with the specific design of each element of the product.
On schematic images, leader lines are drawn from each component part. They begin with arrows from solid lines, and dots from planes. On the shelves of leader lines, serial numbers of positions are indicated. At the same time, Roman numerals are used for elements such as shafts, and Arabic numerals for the rest. Under the shelves of leader lines, the parameters and main characteristics of the components of the circuits are indicated.
GOST 2.703-2011
Group T52
INTERSTATE STANDARD
Unified system of design documentation
RULES FOR EXECUTION OF KINEMATIC SCHEMES
Unified system of design documentation. Rules for presentation of kinematic diagrams
ISS 01.100.20
OKSTU 0002
Date of introduction 2012-01-01
Preface
Preface
The goals, basic principles and basic procedure for carrying out work on interstate standardization are established in GOST 1.0-2015 "Interstate standardization system. Basic provisions" and GOST 1.2-2015 "Interstate standardization system. Interstate standards, rules and recommendations for interstate standardization. Rules for development, adoption , updates and cancellations"
Standard information
1 DEVELOPED by the Federal State Unitary Enterprise "All-Russian Research Institute of Standardization and Certification in Mechanical Engineering" (FSUE "VNIINMASH"), the Autonomous Non-Profit Organization "Research Center for CALS Technologies "Applied Logistics"" (ANO Scientific Research Center for CALS Technologies "Applied Logistics" ")
2 INTRODUCED by the Federal Agency for Technical Regulation and Metrology
3 ADOPTED by the Interstate Council for Standardization, Metrology and Certification (protocol dated May 12, 2011 N 39)
The following voted for adoption:
Short name of the country according to MK (ISO 3166) 004-97 | Abbreviated name of the national standardization body |
|
Azerbaijan | Azstandard |
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Ministry of Economy of the Republic of Armenia |
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Belarus | State Standard of the Republic of Belarus |
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Kazakhstan | Gosstandart of the Republic of Kazakhstan |
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Kyrgyzstan | Kyrgyzstandard |
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Moldova-Standard |
||
Rosstandart |
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Tajikistan | Tajikstandard |
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Uzbekistan | Uzstandard |
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Gospotrebstandart of Ukraine |
4 By Order of the Federal Agency for Technical Regulation and Metrology dated August 3, 2011 N 211-st, the interstate standard GOST 2.703-2011 was put into effect as a national standard of the Russian Federation on January 1, 2012.
5 INSTEAD GOST 2.703-68
6 REPUBLICATION. December 2018
Information about changes to this standard is published in the annual information index "National Standards", and the text of changes and amendments is published in the monthly information index "National Standards". In case of revision (replacement) or cancellation of this standard, the corresponding notice will be published in the monthly information index "National Standards". Relevant information, notices and texts are also posted in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet (www.gost.ru)
1 Application area
This standard establishes the rules for the implementation of kinematic diagrams of products from all industries.
Based on this standard, it is allowed, if necessary, to develop standards establishing the implementation of kinematic diagrams of products of specific types of equipment, taking into account their specifics.
2 Normative references
This standard uses normative references to the following interstate standards:
GOST 2.051-2013 Unified system of design documentation. Electronic documents. General provisions
GOST 2.303-68 Unified system of design documentation. Lines
GOST 2.701-2008 Unified system of design documentation. Schemes. Types and types. General requirements for implementation
Note - When using this standard, it is advisable to check the validity of the reference standards in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet or according to the annually published information index "National Standards", which was published as of January 1 of the current year , and according to the corresponding monthly information indexes published in the current year. If the reference standard is replaced (changed), then when using this standard you should be guided by the replacing (changed) standard. If the reference standard is canceled without replacement, then the provision in which a reference is made to it is applied in the part that does not affect this reference.
3 General provisions
3.1 Kinematic diagram - a document containing mechanical components and their relationships in the form of conventional images or symbols.
Kinematic diagrams are performed in accordance with the requirements of this standard and GOST 2.701.
3.2 Kinematic diagrams can be made as a paper and (or) electronic design document.
It is recommended that diagrams in the form of an electronic design document be made in single sheets, ensuring that this sheet is divided into the required formats when printing.
Note - If the kinematic diagram is performed as an electronic design document, you should additionally be guided by GOST 2.051.
3.3 Complex diagrams can be made dynamic (using multimedia tools) for the most visual presentation.
3.4 Kinematic schemes, depending on the main purpose, are divided into the following types:
- principled;
- structural;
- functional.
4 Rules for executing schemes
4.1 Rules for implementing circuit diagrams
4.1.1 The schematic diagram of the product must show the entire set of kinematic elements and their connections intended to implement, regulate, control and monitor the specified movements of the executive bodies; kinematic connections (mechanical and non-mechanical) provided within the executive bodies, between individual pairs, chains and groups, as well as connections with the source of motion should be reflected.
4.1.2 The schematic diagram of the product is usually depicted in the form of a development (see Appendix A).
It is allowed to inscribe schematic diagrams into the outline of the product image, as well as depict them in axonometric projections.
4.1.3 All elements in the diagram are depicted by conventional graphic symbols (UGO) or simplified in the form of contour outlines.
Note - If the UGO is not established by the standards, then the developer performs the UGO in the margins of the diagram and gives explanations.
4.1.4 Mechanisms that are separately assembled and independently adjustable may be depicted on a schematic diagram of the product without internal connections.
The diagram of each such mechanism is depicted as a remote element on the general schematic diagram of the product that includes the mechanism, or is made as a separate document, and a link to this document is placed on the product diagram.
4.1.5 If the product includes several identical mechanisms, it is allowed to make a circuit diagram for one of them in accordance with the requirements of Section 6, and depict other mechanisms in a simplified manner.
4.1.6 The relative arrangement of elements on the kinematic diagram must correspond to the initial, average or working position of the executive bodies of the product (mechanism).
It is allowed to explain with an inscription the position of the executive bodies for which the diagram is made.
If an element changes its position during operation of the product, then the diagram may show its extreme positions with thin dash-dotted lines.
4.1.7 On the kinematic diagram, without violating the clarity of the diagram, it is allowed:
- move elements up or down from their true position, move them beyond the contour of the product without changing position;
- rotate elements to positions that are most convenient for the image.
In these cases, the conjugate links of the pair, drawn separately, are connected by a dashed line.
4.1.8 If the shafts or axes intersect when depicted on the diagram, then the lines depicting them do not break at the intersection points.
If in the diagram the shafts or axes are covered by other elements or parts of the mechanism, then they are depicted as invisible.
It is allowed to conditionally rotate the shafts as shown in Figure 1.
Figure 1
4.1.9 The ratio of the sizes of the conventional graphic symbols of interacting elements on the diagram should approximately correspond to the actual ratio of the sizes of these elements in the product.
4.1.10 The circuit diagrams show in accordance with GOST 2.303:
- shafts, axles, rods, connecting rods, cranks, etc. - solid main lines of thickness;
- elements shown in simplified form as outlines, gears, worms, sprockets, pulleys, cams, etc. - solid lines of thickness ;
- the outline of the product in which the diagram is inscribed - with solid thin lines of thickness ;
- lines of relationship between conjugated links of the pair, drawn separately, with dashed lines of thickness ;
- lines of relationship between elements or between them and the source of motion through non-mechanical (energy) sections - double dashed lines of thickness;
- calculated relationships between elements - triple dashed lines of thickness .
4.1.11 The schematic diagram of the product indicates:
- the name of each kinematic group of elements, taking into account its main functional purpose (for example, feed drive), which is marked on the shelf of a leader line drawn from the corresponding group;
- main characteristics and parameters of kinematic elements that determine the executive movements of the working parts of the product or its components.
An approximate list of the main characteristics and parameters of kinematic elements is given in Appendix B.
4.1.12 If the schematic diagram of a product contains elements whose parameters are specified during regulation by selection, then on the diagram these parameters are indicated on the basis of calculated data and the inscription is made: “Parameters are selected during regulation.”
4.1.13 If the circuit diagram contains reference, dividing and other precise mechanisms and pairs, then the diagram indicates data on their kinematic accuracy: degree of transmission accuracy, values of permissible relative movements, turns, values of permissible backlash between the main driving and actuating elements, etc. .d.
4.1.14 On the circuit diagram it is allowed to indicate:
- limit values of the speed of the shafts of kinematic chains;
- reference and calculation data (in the form of graphs, diagrams, tables), representing the sequence of processes over time and explaining the connections between individual elements.
4.1.15 If the schematic diagram is used for dynamic analysis, then it indicates the required dimensions and characteristics of the elements, as well as the highest load values of the main driving elements.
This diagram shows the shaft and axle supports taking into account their functional purpose.
In other cases, the supports of shafts and axles can be depicted with general conventional graphic symbols.
4.1.16 Each kinematic element shown in the diagram is usually assigned a serial number, starting from the source of motion, or alphanumeric designations (see Appendix B). Shafts may be numbered in Roman numerals, other elements are numbered only in Arabic numerals.
Elements of purchased or borrowed mechanisms (for example, gearboxes, variators) are not numbered, but a serial number is assigned to the entire mechanism as a whole.
The serial number of the element is placed on the shelf of the leader line. Under the shelf, leader lines indicate the main characteristics and parameters of the kinematic element.
The characteristics and parameters of kinematic elements can be placed in a list of elements, drawn up in the form of a table in accordance with GOST 2.701.
4.1.17 Replaceable kinematic elements of setting groups are indicated in the diagram in lowercase letters of the Latin alphabet and the characteristics for the entire set of replaceable elements are indicated in the table. Such elements are not assigned serial numbers.
It is allowed to carry out the table of characteristics on separate sheets.
4.2 Rules for executing block diagrams
4.2.1 The block diagram shows all the main functional parts of the product (elements, devices) and the main relationships between them.
4.2.2 Structural diagrams of a product are presented either as a graphic image using simple geometric figures, or as an analytical record that allows the use of an electronic computer.
4.2.3 The structural diagram must indicate the names of each functional part of the product if a simple geometric figure is used to designate it. In this case, the names are usually written inside this figure.
4.3 Rules for executing functional diagrams
4.3.1 The functional diagram shows the functional parts of the product involved in the process illustrated by the diagram, and the connections between these parts.
4.3.2 Functional parts are depicted with simple geometric figures.
To convey more complete information about the functional part, it is allowed to place appropriate symbols or an inscription inside the geometric figure.
4.3.3 The functional diagram must indicate the names of all functional parts depicted.
4.3.4 For the most visual representation of the processes illustrated by the functional diagram, the designations of the functional parts should be placed in the sequence of their functional connection.
It is allowed, if this does not interfere with the clarity of the process representation, to take into account the actual location of the functional parts.
Appendix A (for reference). An example of a basic kinematic diagram
Appendix A
(informative)
Appendix B (for reference). Approximate list of main characteristics and parameters of kinematic elements
Appendix B
(informative)
Table B.1
Name | Data indicated on the diagram |
1 Motion source (engine) | Name, type, characteristics |
2 Mechanism, kinematic group | Characteristics of the main executive movements, range of regulation, etc. Gear ratios of the main elements. Dimensions that determine the limits of movement: length of movement or angle of rotation of the executive body. The direction of rotation or movement of elements on which the receipt of specified executive movements and their consistency depend. It is allowed to place inscriptions indicating the operating modes of the product or mechanism that correspond to the indicated directions of movement. Note - For groups and mechanisms shown in the diagram conditionally, without internal connections, the gear ratios and characteristics of the main movements are indicated. |
3 Reading device | Measurement limit or division value |
4 Kinematic links: | |
a) belt pulleys | Diameter (for replacement pulleys - the ratio of the diameters of the driving pulleys to the diameters of the driven pulleys) |
b) gear | Number of teeth (for gear sectors - the number of teeth on a full circle and the actual number of teeth), module, for helical wheels - the direction and angle of inclination of the teeth |
c) rack | Module for helical racks - direction and angle of inclination of teeth |
d) worm | Axial module, number of starts, type of worm (if it is not Archimedean), direction of turn and diameter of the worm |
d) lead screw | The course of the helix, the number of passes, the inscription "lion." - for left-hand threads |
e) chain sprocket | Number of teeth, chain pitch |
g) cam | Parameters of curves that determine the speed and limits of movement of the leash (pusher) |
Appendix B (recommended). Letter codes for the most common groups of elements
Table B.1
Letter code | Group of mechanism elements | Example element |
Mechanism (general designation) | ||
Elements of cam mechanisms | Cam, pusher |
|
Miscellaneous elements | ||
Elements of mechanisms with flexible links | Belt, chain |
|
Elements of lever mechanisms | Rocker arm, crank, link, connecting rod |
|
Motion source | Engine |
|
Elements of Maltese and ratchet mechanisms | ||
Elements of gear and friction mechanisms | Gear, rack and pinion gear sector, worm |
|
Clutches, brakes |
UDC 62:006.354 | ISS 01.100.20 | ||
Key words: design documentation, kinematic diagram, circuit diagram, block diagram, functional diagram |
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Electronic document text
prepared by Kodeks JSC and verified against:
official publication
M.: Standartinform, 2019
