Kinematic schemes. Symbol of elements of kinematic diagrams What is indicated on the kinematic drawing

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 schemes

Purpose 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 others. Under the shelves of leader lines, the parameters and main characteristics of the components of the circuits are indicated.

In order to schematically depict the main components of a machine tool or other mechanism, kinematic diagrams are used.

In such diagrams, components, details, and interactions between individual elements of the mechanism are depicted conventionally. Each standard element has its own designation.

How to read kinematic diagrams of machine tools

In order to learn to read kinematic diagrams, you need to know the designations of individual elements and learn to understand the interaction of individual components. First of all, we will study the most common designations of the most common elements; symbols on kinematic diagrams are presented in GOST 3462-52.

Shaft designation

The shaft on the kinematic diagram is indicated by a thick straight line. The spindle diagram shows the tip.

Designation of bearings in diagrams

The bearing designation depends on its type.

Sleeve bearing depicted in the form of ordinary bracket supports. If a thrust bearing is used, the supports are shown at an angle.

Ball bearings on the kinematic diagrams of the machines are depicted as follows.

The balls in bearings are conventionally depicted as a circle.

In conditional images roller bearings the rollers are shown as rectangles.

Schematic designation of parts connections

Kinematic diagrams depict various types of shaft and part connections.

The designation of the coupling depends on its type, the most common of which are:

cam
friction

The designations of one-way couplings on the kinematic diagrams of machine tools are shown in the figure.

The designation of a double-sided coupling can be obtained by mirroring the horizontal diagram of a single-sided coupling.

Designation of gears on machine diagrams

Gears are one of the most common elements of machine tools. The symbol allows you to understand what type of transmission is used - spur, helical, chevron, bevel, worm. In addition, using the diagram you can find out which wheel is larger and which is smaller.

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 – thrust one-sided
Connection of the part to the shaft: a – free during rotation b – movable without rotation c – blind
Shaft connection: a – blind b – articulated
Clutches: a – single-sided cam b – double-sided cam c – double-sided friction (without specifying the type)
Step pulley mounted on a shaft
Open flat belt transmission
Chain transmission (without specifying the type of chain)
Gear transmissions (cylindrical): a – general designation (without specifying the type of teeth) b – with straight teeth c – with oblique teeth
Gear transmissions with intersecting shafts (bevel): a – general designation (without specifying the type of teeth) b – with straight c – with spiral d – with circular teeth
Rack and pinion transmission (without specifying the type of teeth)
Screw transmitting movement
Nut on the screw transmitting movement: a – one-piece b – detachable
Electric motor
Springs: a – compression b – tension c – 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, 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.

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 to be 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 the pair of wheels 1 - 2 is in front, and the pair 3 - 4 is located behind it.

Rice. 10.1.Gear diagram

Another feature of the image of gears is the use of so-called expanded images. In Fig. 10.2 there are two types of gearing schemes: undeveloped (a) and expanded (b).

Rice. 10.2. Gear diagram images

The arrangement of the wheels is such that in the left view, wheel 2 overlaps part of wheel 1, which may result in confusion 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 shows an example of the kinematic diagram of the gearbox of a lathe, and in Fig. 10.3, and 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.

The concept of a part and a product

In the process of any work, a person always strives for

facilitating its implementation. As a result, every day

new complex devices and machines appear around the world,

capable of producing useful things or performing certain works faster and with better quality.

Technological development:

a) woodworking;

b) metalworking;

c) agricultural;

d) textile.

Machines, mechanisms and other items made

as a result of human technological activity are called products.

Product - an item or set of items manufactured at an enterprise.

The product is the result of a manufacturing process

The product may consist of simpler parts,

Which are called details.

A part is a product made from one

piece of material, such as a shaft, gear,

nut, screw, etc.

In modern technology, parts are divided into two

main groups

The first includes parts that are widely

used in most machines (bolts, nuts, washers, etc.), they are called standard.

The second group is the parts that are used

only in some individual machines (aircraft propeller, ship propeller, sewing machine foot, etc.). They are called special, or original.

Methods for manufacturing parts

Parts are made from different materials in different ways

ways. The most common of them is cutting. On turning, milling and other machines, the cutter cuts off the excess layer from the material, leaving the desired shape and dimensions of the part.

Manufacturing

cutting parts:

on lathes;

on drilling machines;

on sawing machines

Methods for manufacturing parts

Commonly used economical production method

parts are casting.

Molten metal is poured into molds

for further hardening and formation of cast

Casting parts:

a) industrial casting;

b) casting diagram

Methods for manufacturing parts

Stamping is the process of making parts.

Required sizes and shapes under the influence of mechanical

Loads on a workpiece placed in a special device - a stamp.

In mechanical engineering, a product is an item of production to be manufactured. The product is a machine, device, mechanism, tool, etc. and their components: assembly unit, detail. An assembly unit is a product whose components are to be connected at the enterprise separately from other elements of the product.

An assembly unit, depending on the design, can consist either of individual parts or include assembly units of higher orders and parts. There are assembly units of the first, second and higher orders. The first-order assembly unit enters directly into the product. It consists either of individual parts or of one or more second-order assembly units and parts. An assembly unit of the second order is dissected into parts or assembly units of the third order and parts, etc. An assembly unit of the highest order is dissected only into parts. The considered division of the product into its component parts is carried out according to technological characteristics.

A part is a product made from a material that is homogeneous by name and brand without the use of assembly operations. A characteristic feature of the part is the absence of detachable and permanent connections in it. A part is a complex of interconnected surfaces that perform various functions during machine operation.

The production process is the totality of all the actions of people and tools necessary at a given enterprise for the manufacture and repair of products. For example, the production process of making a machine includes not only the manufacture of parts and their assembly, but also the extraction of ore, its transportation, its transformation into metal, and the production of metal blanks. In mechanical engineering, the production process is part of the overall production process and consists of three stages: obtaining a workpiece; converting a workpiece into a part; product assembly. Depending on the specific conditions, the listed three stages can be carried out at different enterprises, in different workshops of the same enterprise, and even in the same workshop.

A technological process is a part of the production process that contains targeted actions to change and (or) determine the state of the subject of labor. A change in the state of an object of labor is understood as a change in its physical, chemical, mechanical properties, geometry, and appearance. In addition, the technological process includes additional actions directly related to or accompanying a qualitative change in the production facility; these include quality control, transportation, etc. To implement the technological process, a set of production tools, called technological equipment, and a workplace are required.

Technological equipment is a means of technological equipment in which, to perform a certain part of the technological process, materials or workpieces, means of influencing them, as well as technological equipment are placed. These include, for example, foundry machines, presses, machine tools, test benches, etc.

Technological equipment is a means of technological equipment that complements technological equipment to perform a certain part of the technological process. These include cutting tools, fixtures, and measuring instruments. Technological equipment together with technological equipment, and in some cases a manipulator, is usually called a technological system. The concept of “technological system” emphasizes that the result of the technological process depends not only on the equipment, but also, no less, on the fixture, tool, and workpiece.

A workpiece is an object of labor from which a part is made by changing its shape, size, surface properties or material. The workpiece before the first technological operation is called the initial workpiece. The workplace is an elementary unit of the enterprise structure, where the performers of the work and the serviced technological equipment, lifting and transport vehicles, technological equipment and objects of labor are located.

For organizational, technical and economic reasons, the technological process is divided into parts, which are commonly called operations.

A technological operation is a completed part of a technological process performed at one workplace. An operation covers all actions of equipment and workers on one or more assembled production objects. When processing on machines, the operation includes all the actions of the worker who controls the technological system, installation and removal of the object of labor, as well as the movements of the working parts of the technological system. The content of operations varies widely - from work performed on a separate machine or assembly machine in conventional production, to work performed on an automatic line, which is a complex of technological equipment connected by a single transport system and having a single control system in automated production. The number of operations in the technological process varies from one (production of a part on a rod machine, production of a body part on a multi-operational machine) to dozens (manufacture of turbine blades, complex body parts).

The operation is formed mainly according to the organizational principle, since it is the main element of production planning and accounting. All planning, accounting and technological documentation is usually developed for an operation. In turn, a technological operation also consists of a number of elements: technological and auxiliary transitions, installation, positions, and working stroke.

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 objects of labor, but are necessary to complete the technological transition (for example, installing a workpiece, changing tools, etc.). The transition can be performed in one or several working strokes. A working stroke is a completed part of a technological transition, consisting of a single movement of the tool relative to the workpiece, accompanied by a change in the shape, size, surface quality and properties of the workpiece. When processing a workpiece with removal of a layer of material, the term “allowance” is used.

The technological process of machining is a part of the production process directly related to changing the shape, size or properties of the workpiece, performed in a certain sequence. The technological process consists of a number of operations.

An operation is a completed part of the technological process of processing one or several simultaneously processed workpieces, performed at one workplace by one worker or team. The operation begins from the moment the workpiece is installed on the machine and includes all subsequent processing and removal of the machine. The operation is the main element in the development, planning and standardization of the technological process of processing workpieces. The operation is performed in one or more workpiece installations.

Installation is a part of a technological operation performed with constant fixation of the workpieces being processed. In the installation, individual workpiece positions are allocated.

Position is a fixed position occupied by a fixed workpiece together with a fixture relative to a tool or a stationary piece of equipment to perform a certain part of the operation.

A technological operation can be performed in one or several transitions.

A transition is a part of an operation that is characterized by the constancy of the cutting tool, processing mode and surface being processed. In turn, the transition can be divided into smaller elements of the technological process - passages. During the pass, a layer of material is removed without changing the machine settings.

The development of all these elements of the technological process largely depends on the nature of the workpiece and the amount of allowances for its processing.

A workpiece is a production item from which a part is made by changing its shape, size, roughness and material properties. Blanks are produced in foundries (castings), forges (forgings, stampings) or blanks (cut from rolled products). The method of producing blanks depends on the design requirements for the parts, material properties, etc.

When developing a technological process, it is very important to choose the right technological (installation and measuring) bases.

The mounting base is understood as the surface of the workpiece on which it is fixed and along which it is oriented relative to the machine and the cutting tool. The setting base used in the first operation is called the roughing base, and the base that was formed as a result of initial processing and is used to secure and orient the workpiece for further processing is called the finishing base.

Measuring bases are the workpiece surfaces from which dimensions are measured when monitoring processing results.

When choosing technological bases, they are guided by the rules of unity and constancy of bases. According to the first rule, the same surfaces should be used as installation and measuring bases, if possible. The second rule requires that as many surfaces as possible be processed from one base. Compliance with these rules ensures higher processing accuracy. The rough installation base is usually taken to be the surface that is not subject to further processing or has the smallest allowance for processing. This allows you to avoid defects due to insufficient allowance on this surface.

The surfaces selected as mounting bases must allow the workpiece to be securely fastened.

The development of the technological process begins with the analysis of the initial data - the working drawing and the dimensions of the batch of parts (the number of workpieces of the same type to be processed). At the same time, the availability of equipment, devices, etc. is taken into account.

Based on the working drawing and batch sizes, the type and dimensions of the workpiece are determined. Thus, for single production, workpieces are usually cut from section or sheet metal (in this case, the mechanic must determine the dimensions of the workpiece, taking into account processing allowances). In serial and mass production, workpieces are usually produced using casting, free forging or stamping.

For the selected workpiece, technological bases are outlined: first - roughing, then - the base for finishing.

Based on standard technological processes, the sequence and content of technological operations for processing a specific part are determined. When the processing sequence is determined and the operations are outlined, the necessary equipment, technological equipment (working and measuring tools, fixtures) and auxiliary materials (products for painting workpieces when marking, cooling and lubricants, etc.) are selected for each of them.

In the case of processing parts on machines, processing modes are calculated and assigned. Then the technological process is normalized, i.e., the time standard for performing each technological operation is determined.

State standards establish the Unified System of Technological Preparation of Production (USTPP). The main purpose of the ESTPP is to establish a system for organizing and managing the process of technological preparation of production. ESTPP provides for the widespread use of progressive standard technological processes, standard technological equipment and means of mechanization and automation of production processes.

The metalworking area at an industrial enterprise is an independent production unit of the workshop, which occupies a significant area and is equipped with workbenches, tools, main and auxiliary equipment.

The staff of the site consists of several dozen or even several hundred people. Depending on the size of the enterprise, independent assembly and metalwork shops can be organized, which may include production departments (a tool storeroom, a storeroom for materials and components, a control department and a number of other production and auxiliary departments).

Separate machine parts and devices manufactured in other areas are delivered to the metalworking and assembly area. From these parts, site workers assemble assembly units, kits or assemblies from which machines are assembled. The products of the metalworking and assembly section of the workshop can be presented in the form of parts. However, the site, as a rule, does not provide other maintenance services for the workshop or plant.

The metalworking section of the workshop should be equipped with workbenches equipped with vices, manual and mechanical drilling machines, tool sharpening machines, mechanical saws, lever shears, plates for straightening and lapping, marking plates, portable electric grinding machines, machines and tools for soldering, mechanization equipment lifting and transport works, racks and containers for parts, waste containers, tool storage.

Occupational Health, Safety and Health

Work is safe if it is performed under conditions that do not threaten the life and health of workers.

At industrial enterprises, all responsibility for occupational health and safety lies with the heads of the enterprise, workshop, section (director, workshop manager, foreman). Each enterprise must have a labor safety department that monitors compliance with safe work conditions and implements measures to improve these conditions.

Workers are required to comply with the requirements of labor protection instructions.

Before starting work, the employee must undergo occupational safety training.

Occupational hygiene is a branch of preventive medicine that studies the influence of the labor process and factors of the working environment on the human body in order to scientifically substantiate the standards and means of preventing occupational diseases and other adverse consequences of exposure to working conditions on workers.

An employee starting work must be healthy and neatly dressed. Hair must be tucked under a headdress (beret, headscarf).

Locksmith rooms must have sufficient lighting in accordance with current regulations. There are natural (daylight) and artificial (electric) lighting. Electric lighting can be general and local.

The floor in the metalworking room should be made of end blocks, wooden beams or asphalt mixtures. Avoid contaminating the floor with oil or grease as this may cause an accident.

To avoid accidents at the enterprise and in the workplace, it is necessary to comply with safety requirements.

All moving and rotating parts of machines, equipment and tools must have protective screens. Machinery and equipment must be properly grounded. Electricity sources must comply with current technical requirements. Where fuses are installed, special protective equipment must be used.

Maintenance and repair of equipment and accessories must be carried out in accordance with the operating and repair instructions. The tool must be in good working order.

Information (for example, “Water for drinking”, “Locker room”, “Toilets”, etc.), warnings (for example, “Attention - train”, “Stop! High voltage”, etc.) and prohibitions should be posted in prominent places (for example, “No smoking!”, “Grinding without glasses is prohibited,” etc.) signs.

Steel and hemp ropes of various lifting and transport equipment and accessories, and seat belts must be systematically tested for strength.

Fire and access routes, passages for pedestrians (both on the territory of the enterprise and indoors) must be safe for traffic.

Damaged ladders should not be used. Open channels and manholes should be well marked and fenced.

At the enterprise and at the workplace, the employee’s thoughts should be focused on the work assigned to him, which must be completed quickly and efficiently. Violations of labor and production discipline and alcohol consumption are unacceptable at work.

At the end of work, you should tidy up your work area, put tools and equipment in the tool box, wash your hands and face with warm water and soap, or take a shower.

Overalls should be stored in a closet specially designed for this purpose.

Each site or workshop must be equipped with a first aid kit (first aid station). The first aid kit should contain sterile bandages, cotton wool, disinfectants, plaster, bandages, tourniquets, sterile bags, triangular scarves, splints and stretchers, valerian drops, painkillers, cough tablets, ammonia, iodine, pure alcohol, baking soda.

At an enterprise or workshop, teams (teams) of rescuers or sanitary instructors are formed from among specially trained workers.

A rescuer or sanitary instructor provides first aid to the victim in case of accidents, calls emergency assistance, transports the victim home, to a clinic or hospital, and does not leave the victim until he is provided with the necessary medical care.

Employees of enterprises and metalworking shops who work with metal most often experience the following occupational injuries: cuts or damage to the surface of tissues with a sharp tool, eye damage from metal fragments or shavings, burns, and electric shock.

A burn is damage to body tissue that has been in direct contact with a hot object, steam, hot liquid, electric current, or acid.

There are three degrees of burns: first degree - redness of the skin, second - the appearance of blisters, third - necrosis and charring of tissue.

For minor burns (first degree), first aid is provided using cleansing agents. Do not apply a compress with oil or any ointment as this may lead to further irritation or infection, which will require long-term treatment. The burned area should be bandaged with a sterile bandage. A victim with first, second or third degree burns should be immediately sent to the hospital.

In case of electric shock, the victim is first freed from the source of the injury (to do this, it is necessary to break the connection, turn off the voltage or drag the victim away from the site of the injury, while wearing dielectric shoes and gloves) and lay him on a dry surface (boards, doors, blanket, clothes), unbutton clothes that are constricting the throat, chest and stomach.

Clenched teeth need to be unclenched, the tongue should be stretched out (preferably with a handkerchief) and a wooden object should be placed in the mouth to prevent the mouth from closing spontaneously. After this, artificial respiration begins (15–18 shoulder movements or breaths per minute). Artificial respiration should be interrupted only on the recommendation of a doctor or if the victim begins to breathe on his own.

The most effective method of artificial respiration is the “mouth to mouth” and “mouth to nose” methods.

If a fire occurs, you should stop work, turn off electrical installations, equipment, ventilation, call the fire department, inform the organization’s management and begin extinguishing the fire using available fire extinguishing means.

Safety measures when performing certain types of work are briefly discussed in the relevant sections.

Work on the construction of buildings and structures, installation of technological, sanitary and electrical equipment, automation and low-current devices is carried out in accordance with design and estimate documentation specially developed for each facility. When constructing industrial facilities, working drawings must contain sets of architectural, construction, sanitary, electrical and technological documentation.

During electrical installation work, working drawings of the electrical technical part of the project are used, including technical documentation for external and internal electrical networks, substations and other power supply devices, power and lighting electrical equipment. When accepting working documentation, you need to pay attention to taking into account the requirements for the industrialization of installation work, as well as the mechanization of work on laying cables, rigging components and blocks of electrical equipment and their installation.

When developing design documentation, the requirements of the electrical installation technology of the organization that will carry out the installation are taken into account. In the installation area (directly at the site of installation of equipment and laying electrical networks in workshops and buildings), installation work consists of installing large blocks of electrical devices, assembling components and laying networks. Therefore, working drawings are completed according to their purpose: for procurement work, i.e. for ordering blocks and assemblies at manufacturing plants or in workshops of electrical installation workpieces (EPW), and for installation of electrical devices in the installation area.

Openings, niches, openings for electrical installations must be taken into account in the drawings of the architectural and construction part of the project. Channels or pipes for laying wires, niches, nests with embedded parts for installing distribution cabinets, plug sockets, switches, bells and bell buttons should be included in the working drawings of building structures (reinforced concrete, gypsum concrete, expanded clay concrete floor panels, wall panels and partitions, reinforced concrete columns and factory-made crossbars). The installation sites of electrical equipment and the routes for laying electrical networks must be linked to the installation sites of technological and plumbing equipment and the routes of other utility networks. Installation of off-shop cable and overhead lines is carried out according to the laying drawings of the specified line routes, linking them to the coordinate grids of the building and structure. As a rule, overhead line supports, their foundations, intersections of cable lines and cable structures are made according to standard drawings. For the installation of power electrical equipment, floor plans of the building and workshops are developed, indicating and coordinating on them the routes for laying supply and distribution power networks and placing busbars, power supply points and cabinets, electrical receivers and ballasts; for the installation of electric lighting - indicating and coordinating the supply lines on them and group networks, lamps, lighting points and panels.

The electrical installation department receives design documentation from the customer and orders the production of electrical installation blocks and assemblies at manufacturing plants and at the bases of installation organizations. On the working drawings transferred to the installation organization, a stamp or inscription is placed: “Approved for production” signed by the responsible representative of the customer. The customer also provides the installation organization with diagrams and installation instructions received from equipment manufacturers.

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 symbols 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

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, P= 1440 rpm.

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 to be 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.

In accordance with GOST 2.703 - 68, the kinematic diagram must depict the entire set of kinematic elements and their connections, all kinematic connections between pairs, chains, etc., as well as connections with sources of motion.

The kinematic diagram of the product should be drawn, as a rule, in the form of a development. It is allowed to depict diagrams in axonometric projections and, without disturbing the clarity of the diagram, move elements up or down from their true position, as well as rotate them to positions that are most convenient for depiction. In these cases, the conjugate links of the pair, drawn separately, should be connected by a dashed line.

All elements of the diagram must be depicted with conventional graphic symbols in accordance with GOST 2.770 - 68 (Fig. 10.1) or simplified external outlines.

The elements of the diagram should be depicted:

shafts, axes, rods, etc. - with solid main lines of thickness S;

elements depicted in simplified external outlines (gears, worms, pulleys, sprockets, etc.) - with solid thin lines of thickness S/2;

the outline of the product in which the diagram is inscribed - with solid thin lines of thickness S/3;

kinematic connections between the conjugate links of the pair, drawn separately, by dashed lines of thickness S/2;

the extreme positions of the element that changes its position during operation of the product - thin dash-dotted lines with two dots;

shafts or axes covered by other elements (invisible) - dashed lines.

Each kinematic element should be assigned a serial number, starting from the source of motion. The shafts are numbered with Roman numerals, the remaining elements are numbered with Arabic numerals. Elements of purchased or borrowed mechanisms (for example, gearboxes) are not numbered; a serial number is assigned to the entire mechanism.

The serial number is placed on the leader line shelf. Under the shelf it is necessary to indicate the main characteristics and parameters of the kinematic element:

power of the electric motor, W and speed of its shaft, min -1 (angular speed, rad/s) or power and speed of rotation of the input shaft of the unit;

torque, N·m, and rotational speed, min -1 of the output shaft;

the number and angle of inclination of the teeth and the module of gears and worm wheels, and for a worm - the number of starts, the module and diameter coefficient;

diameters of belt pulleys; number of sprocket teeth and chain pitch, etc.

If the diagram is overloaded with images of connections and kinematic links, the characteristics of the diagram elements can be indicated in the field of the drawing - diagram in the form of a table. It provides a complete list of constituent elements.

Let us explain some aspects of the process of reading and executing kinematic diagrams, and, first of all, with the accepted conventions when creating kinematic diagrams.

1. The kinematic diagram is usually depicted in the form of a sweep. What does this word mean in relation to the kinematic diagram?

The fact is that the spatial arrangement of the kinematic links in the mechanism is for the most part such that it makes it difficult to depict them on the diagram, since the individual links obscure each other.

This in turn leads to misunderstanding or misconception about the circuit. To avoid this, the circuits use the conditional method of so-called expanded images.

In Fig. 10.1, a shows an image of two pairs of gears. Since gear wheels are usually depicted in kinematic diagrams as rectangles, it is easy to imagine that for a given spatial arrangement of gear wheels their images will overlap in pairs.

To prevent such overlaps, regardless of the spatial location of the kinematic links in the mechanism, they are usually depicted in expanded form, that is, the rotation axes of all mating gears must lie in the same plane, parallel to the image plane (see Fig. 10.1, b).

An example of the development of kinematic links in a diagram.

2. The transition from a constructive scheme to a kinematic one facilitates the figurative perception of the latter (Fig. 10.2). From this diagram it can be seen that crank 1 has a rigid support, which is marked by a thick basic line with shading; piston 2, shown in the kinematic diagram as a rectangle, has a gap with the cylinder walls, which, as stationary elements, also have one-sided hatching. The gap indicates possible reciprocating movement of the piston.

Structural and kinematic diagrams of an internal combustion engine

3. In all diagrams, shafts and axles are depicted with the same thick main line (Fig. 10.3). The difference between them is as follows:

a) shaft supports are depicted by two dashes with a gap along both shaft stops; Since the shafts rotate together with gear wheels (pulleys) mounted and keyed to them, the supports are either plain or rolling bearings. In cases where it is necessary to clarify the type of shaft supports, the standard provides special designations based on the given dashes;

b) the axis is a stationary product, therefore its ends are embedded in stationary supports, marked on the diagram by straight segments with one-sided hatching. The gear wheel mounted on the axle rotates freely when the driven wheel rotates on the shaft.

Shafts and axles on kinematic diagrams

4. Some rules for reading kinematic diagrams:

a) for the most part, the driving gear (pulley) is the smaller of the mating pair, and the larger is the driven one (Fig. 10.4). The letters n 1 and n 2 indicated in the diagram are the designation of the gear ratio or the ratio of the rotation speed n of the driving and driven wheels: n 1 / n 2 ;

Drive shaft and driven shaft on kinematic diagrams

b) in Fig. Figure 10.5 shows a reduction gear, since n 1 > n 2. In a gear drive, the mating gears are made from the same module, so the larger wheel has more teeth. Gear ratio:

where Z 1 and Z 2 are the number of teeth of the gear wheels;

Reducing gear transmission

c) in Fig. 10.6 shows an overdrive, since n 1< n 2 ;

d) in Fig. Figure 10.7 shows transmissions at three speeds: a step-pulley transmission with a flat belt and a gearbox with a movable block of gears.

In a belt drive, for the use of one belt at all stages, the following condition is provided: d 1 + d 2 = d 3 + d 4 = d 5 + d 6, where d 1, d 2, d 3, d 4, d 5, d 6 - pulley diameters in mm.

Rotation is transmitted from shaft I to shaft II (n I and n II).

Rotation frequency:

n II =n I d 1 /d 2 ; n II =n I d 3 /d 4 ; n II =n I d 5 /d 6 .

Overdrive gearing

Three speed gears

In Fig. 10.7, b shows a gearbox for three rotation speeds with a movable block of gears Z 1 - Z 3 - Z 5, which can move along the shaft key I; on shaft II, the wheels are rigidly connected to the shaft with keys.

Shaft speed II:

n II = n I · Z 1 / Z 2 ; n II = n I · Z 3 / Z 4 ; n II = n I · Z 5 / Z 6 .

where Z 1, Z 2, Z 3, ..., Z 6 - the number of wheel teeth.

Since the gears are of one module, then

Z 1 +Z 2 =Z 3 +Z 4 = Z 5 +Z 6.

5. It should be noted that “scale-free” schemes are a relative feature. Thus, for basic kinematic diagrams, 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.

This can be seen from the consideration of the basic kinematic diagrams of the bevel differential of a gear hobbing machine, shown in orthogonal and axonometric projections (see Fig. 10.8). In these diagrams, the geometric dimensions of bevel gears 3...6 are the same.

Kinematic schematic diagram of a bevel differential:

a – orthogonal projection; axonometric projection.

In Fig. 10.9 shows an example of a basic kinematic diagram, which consists of conventional graphic symbols of elements, connections between them and alphanumeric positional designations of elements, as well as constituent elements of the diagram, made in the form of a table. From the image you can imagine the sequence of motion transmission from the engine to the actuator. The table shows the designations of the constituent elements, their explanations and parameters.

Example of a kinematic circuit diagram