Electrical equipment and electric drive of UT16V machine

Contents

Introduction

1. Design and Technical Part

1.1 Machine Assignments

1.2 Brief description of individual units

1.3 Description of kinematic diagram

1.4 Analysis of shortcomings of the existing machine layout

Peculiarities of electric equipment of turning-screw cutters

Requirements for electrical equipment

turning and screw-cutting machines

1.7 Justification and selection of control scheme

1.8 Selection of current and value of supply voltage

1.9 Description of electrical circuit 1.10 Power calculation and selection of motor of main drive

1.11 Power calculation and selection of motor of the mechanism

giving

1.12 Power calculation and selection of cooling pump motor

1.13 Calculation of local lighting

1.14 Features and selection of control equipment

1.15 Calculation and selection of protection equipment 1.16 Selection of wires and supply cable

2. Economics of production

2.1 Organizational Part

2.1.1 Definition of Electrical Installation Scope

2.2 Economic part

2.2.1 Remuneration of workers

2.2.2 Calculation of wages for installation of electrical equipment

2.2.3 Concept of estimates and types of estimates

2.2.4 Preparation of estimates for installation of electrical equipment

3. Special part

3.1 Calculation of main engine

4. Safety precautions

4.1 Organization of safe operation of machines

4.2 Electrical Safety

4.3 Insulation Test Safety Measures

high voltage electrical equipment

5. Electrical installation works

5.1 Selection of connection diagram

5.2 Wiring of industrial mechanisms

6. Graphic part

Sheet 1 General View Drawing

Sheet 2 Kinematic schematic diagram

Sheet 3 Electrical Schematic Diagram

Sheet 4 Electrical Connection Diagram

7. List of sources used

Introduction

Electrification ensures the fulfillment of the task of wide complex mechanization and automation of production processes, which allows increasing the growth rate of public labor productivity. Based on the use of electricity, technical re-equipment of industry, the introduction of new technological processes and the implementation of indigenous entities in the organization and management of production is being carried out, therefore, the role of electrical equipment, that is, the combination of electric machines , devices,

Instruments and devices that convert electrical energy into other types of energy, and automation of technological processes is provided.

Electrical engineering is one of the leading branches of the machine building industry. The manufacturing process of an electrical machine consists of operations in which a variety of process equipment is used. At the same time, the bulk of modern electric machines are manufactured by mass production methods. The specifics of electrical machinery are mainly the presence of processes such as the manufacture and laying of windings of electrical machines for which non-standardized equipment is used, usually manufactured by the machine-building plants themselves. In its predominant part, the technological equipment of electric machine-building plants is typical for mechanical engineering as a whole. Electrical machinery is characterized by a variety of technological processes using electrical energy: foundry, welding, metal forming and cutting. Electric machinery enterprises are widely equipped with electrophied lifting and transportation mechanisms, pump, compressor and fan units. Automation affects not only individual units and auxiliary mechanisms, but to a general extent entire complexes that form fully automated, in-line lines and workshops. Of paramount importance for automation of production are multi-engine drive and electric control means. The development of the electric drive follows the path of simplifying mechanical transmissions and approaching electric motors to the working elements of machines and mechanisms, as well as the increasing use of electric application of drive speed. Complete thyristor converters are widely implemented. The use of thyristor converters not only made it possible to create highly economical DC electric drives, but also opens up great opportunities for using frequency control of AC motors, primarily the simplest and most reliable asynchronous motors with a short-circuited rotor.

The expansion and complexity of the functions performed by the electric drive, the use of new control tools in it requires a high level of training of specialists involved in its design, installation, adjustment and operation. A characteristic of many working machines is the presence of not one, but two or even several interacting actuators. The possibility of taking advantage of electric control and the desire to significantly simplify the kinematics of individual links of the machine led to an automated multi-engine drive, in which various movements on the machine are made from separate motors. Multi-engine drive allows to fully link properties and designs of electric motors with operating conditions and structures of individual machine units. When using a multi-motor drive, the following can be achieved:

smooth and accurate control of the speed of the machine tool and, therefore, the establishment of the most rational processing mode, which reduces machine time, especially a significant reduction in machine time occurs with automatic control of the speed of rotation of the drive during processing;

increase of productivity due to reduction of auxiliary time due to application of separate drives for auxiliary movements carried out at increased speeds;

simplifying the design of the machine due to a decrease in the number of gears and therefore improving the accuracy of operation;

accelerating and facilitating the machine control process through the use of automatic control methods and mutual coordination of movements of individual elements of the machine using relatively simple electrical connections;

automatic monitoring of operation of individual machine mechanisms.

A rationally designed machine and its electric drive shall ensure the fullest use of the cutting properties of the tool used in all possible operations on the machine. Therefore, in order to design the electric drive and automatic control circuit of the machine, it is necessary to know the peculiarities of the type of processing, the main and auxiliary movements and be able to determine the indicators characterizing the possible cutting modes on the machine, such as the required ranges of the speeds of the machine working elements, the power on the shaft of the main motor, maximum feed forces, machine time and others.

In modern industrial production, public utilities and other areas, the largest use is electric drive, which consumes more than 60% of the electricity generated in the country. The capabilities of the modern electric drive continue to be constantly expanded due to the use of achievements in related fields of science and technology - electrical engineering and electrical engineering, electronics and computer engineering, automation and electrical engineering.

Purpose of the machine

Turning machines are among the most common metal cutting machines and are widely used in industrial enterprises, in repair shops. This group includes: universal lathes and lathes, revolvers, lathes - frontal, carousel, lathes - copying machines, lathes and semi-automatic machines. The group of lathes is very numerous both in its design and in its technological purpose. To process a part on a lathe, it is rotated about its axis, and the cutter moves along the part and removes a layer of metal from it. Part is rotated by machine spindle while machine feed mechanism translates cutter. Cutting tool is fed by translational displacement of calipers. During turning, the main movement is the rotation of the workpiece, the feed movement is the translational movement of the cutter. Auxiliary movements on the lathe include the quick entry and retraction of the caliper carriage with cutting tools, the clamping and pressing of the workpiece, and the movement of the tailstock. The speed at which the point of contact of the workpiece with the cutter moves with respect to it is called the cutting speed. The cutting speed depends on the quality of the material to be treated, the cutter material and its geometrical shape, as well as on the method and conditions of cooling the carved and processed product. Higher cutting speeds correspond to lower feed and cutting depths. Then, obviously, lower cutting force corresponds to higher cutting speeds, and higher cutting forces correspond to lower cutting speeds; hence the constancy of cutting power.

And so, on lathes, external, internal and end surfaces are processed, cylindrical, conical and shaped shape is rotated, as well as grooves are cut, external and internal threads are cut. The most used of the lathes of the turning group were universal lathes - screw-cutting machines. In electrical engineering, such machines include the universal lathe - screw-cutting machine of the UT16V model, which performs a variety of lathe work, including turning shafts, bearing boards and other parts of electrical machines, as well as for cutting threads: metric, inch, modular, thread and Archimedean spiral. (1)

Brief description of the main nodes

The main units of the UT16V machine are:

bed;

front (spindle) head with speed box and spindle;

caliper;

hind head;

feed box;

apron;

cabinet with electrical equipment

The frame of a box-shaped universal turning-screw machine with transverse U-shaped ribs is the main bearing structure of the machine. Machine has two prismatic guides. Front component serves for carriage movement, and rear component - for rear head movement. Guides subjected to hardening with subsequent grinding. In the niche of the right end of the bed there is an electric motor of accelerated moves. The bed is installed on two hollow pedestals. In the first pedestal on the plate, having vertical movement for tension of belts, a main movement electric motor is mounted. At the rear of the machine, an electric pump with a capacity of 22 l/min is installed on the RH pedestal, giving cooling liquid from the tank located in the RH pedestal to the place of products processing. The machine can be supplied on a solid base instead of pedestals.

The spindle is a hollow shaft through which bar material can be passed when machined. A cartridge or a plan washer is screwed onto the spindle to secure the workpiece, and the front center can also be installed during processing of the item in the centers.

The front end of the spindle has a groove for protectors preventing spontaneous decay of the cartridge when the machine stops. Start, stop and start of accelerated reverse travel are performed by handle of spindle start, stop and reversal.

The speed box is fixed in the first head part of the bed. Motion to the speed box is transmitted from an individual electric motor placed in the left leg of the machine, through a belt gear to the pulley of the friction shaft. Inside the gearbox, movement goes through the friction roller and gear mechanism to the spindle and gear chains. The movement of the gears along the spline rollers, carried out by the spindle speed setting handles, allows 23 different speeds of rotation of the spindle at forward travel and 12 speeds at reverse accelerated travel. The movement of the handle selects the required number of revolutions according to the table placed on the handle, and by rotating the other handle the required number of revolutions of the spindle is set. All gears are made of chrome steel with appropriate heat treatment. In splined joints, the base is the outer diameter of the splined roller. In order to avoid breakage of gear teeth, do not change the speed of the spindle on the move. Number of teeth and module are applied on ends of replaceable gears. Do not forget about regular lubrication of replaceable gears. The speed box mechanism allows you to:

a) increase by 8 and 32 times the ratio between the feed chain and the thread cutting spindle with increased pitch;

b) cut right and left threads;

c) divide at cutting of multistart threads into 2, 3.4, 5, 6, 10, 12, 15, 20, 30, and 60 entries

by twisting the spindle with the supply circuit disconnected for the corresponding number of divisions.

The caliper is used to secure the cutting tool and communicate to it the feed movements: longitudinal and transverse; thanks to this, and the cross structure, the caliper can move in the longitudinal direction along the guide frames and transverse along the carriage guides. Both of these movements can be carried out either by a mechanical reverse drive or by hand. In addition, the upper part of the caliper carrying the tetrahedral cutting head has independent manual control for longitudinal movement along the guides of the rotary part of the caliper and can be rotated by an angle from - 90 to + 90 degrees. For convenience of determining values, movement of cutter and cross slides during machining of parts, caliper is equipped with scale rulers. A ruler with a division price of 5 mm is applied to the sled slides. A ruler is installed on the carriage with the price of dividing 10 mm by the diameter of the articles, along which the values ​ ​ of the movement of the transverse slides are controlled using a fixed sight. When machining the end faces of parts in heavy cutting modes, it is necessary to tighten the carriage pressure bar with a screw. On the lower part of the caliper there can be additionally installed a rear cutter holder .

The tailstock is used as a second support in processing in the centers of relatively long products and has a rigid structure. With one handle through the system of levers and eccentric it is attached to the bed. An additional bolt is provided for stronger attachment. The rear head has a retractable pinol, in which a rear center or a cutting tool for processing holes is fixed - drills, throwers, reamers. The head moves along the bed guides. The pinol is moved by rotation of the screw, and the handle is attached. When drilling the tailstock, you can use the mechanical feed from the carriage, for this you need to connect the carriage and the tailstock with a lock. When turning the cone, the body of the rear head moves in the transverse direction with the help of screws .

The feed box receives movement from the speed box through replaceable gears, the feed box mechanism allows you to obtain through the lead screw with a pitch of 12 mm, all types of threads provided by GOST and the necessary supplies :

metric with spacing from 1 to 12 mm;

inch from 2 to 24 threads per inch;

pitching from 1 to 96 pitches;

modular with spacing from 0.5 to 3 modules

By means of the pitch increasing mechanism, with the number of spindle revolutions from 12.5 to 40, it is possible to obtain threads with an increased pitch exceeding the normal one by 32 times, and with the number of revolutions from 90 to 160 - by 8 times in accordance with the table data on the drum handle. Through the running roller the caliper at any number of revolutions of the spindle receives longitudinal supplies from 0, 070 to 2.08 mm per spindle rotation and transverse feed from 0,033 to 1, 04 mm per spindle turn, and at rpm from 50 to 630 per minute - longitudinal feeds from 2,08 to 4.16 mm per spindle revolution and transverse - from 1.04 to 2.08 mm per spindle revolution. For more precise threads in the feed box, a position is provided where the screw is connected directly, bypassing the feed chain mechanism. At the same time, the required step is selected by replaceable gears. The types of threads, the actuation of the lead screw directly and the supply are set by turning the actuation handle to the supply, thread, lead screw and Archimedean spiral. By turning of this handle the movement is transmitted to cams, which are installed through levers and gear blocks in appropriate positions. By turning the installation handle of the thread feed and pitch, the selection of a row of threads or feed according to the table is achieved, and in order to obtain the required value from the thread or feed row, it is necessary to pull the drum disk by the handles until the hairlines of the disk coincide with the drum risk, and then feed the disk forward to the previous position. This sets the cone lever to the appropriate position. For quick movement of carriage and caliper in feed box overrunning clutch is mounted on axle of running shaft.

The apron is connected to the lower carriage of the caliper and moves with it along the bed. It has four cam clutches that allow for a straight and reverse carriage at the caliper. The apron has a locking device preventing simultaneous actuation of longitudinal and transverse feed of the caliper, simultaneous actuation of the lead screw and the lead roller, as well as a safety cam clutch, which operates under the action of forces arising during overload of the apron. The clearance of the coupling of the mother nut with the lead screw is graduated at the factory. During repair, the clearance is set by the screw located in the end face of the mother nut housing from below the apron.

In addition to the main units, the machine design includes a guard, replaceable gears, a stop, cartridges, lunettes, a center tool holder, a running shaft and a lead screw. The stop is a device installed on the machine bed and serves for work on the stop. At the same time, the speed of the carriage can reach no more than 250 mm per minute.

The guard is designed to protect against flying chips on the lower part of the caliper, which is folded back to the stop during installation and removal of parts. The railing has a swivel screen that can be positioned depending on the location of the lighting.

Replaceable gears are designed to transmit movements from the speed box to the feed box.

The machine is equipped with a self-centering three cam cartridge with a diameter of 240mm, four cam cartridge with a diameter of 400mm and a drive plate. By means of flanges, cartridges and drive plates are screwed on the spindle thread until stop and are kept from screwing during shutdown and reverse of the spindle by two safety washers. Accuracy of the cartridge fit on the spindle is checked by the indicator against the control band located above the external cylindrical surface of the cartridge housing. Radial run-out must not exceed 0.02mm.

For a separate fee with the machine, lunettes can be delivered: a movable roller with an installation diameter of 20 to 110 mm and a bushing for cutting threads on screws.

Center tool holder is used for machining holes with manual and mechanical feeding of carriage. The holder is installed in the position of the cutter holder, marked with the symbol indicating the drill, until it thrusts against its side face and is clamped with screws (1), (3)

Description of kinematic diagram

Kinematic diagram of the machine is presented in the graphic part, sheet 3. The kinematic diagram shows that each kinematic connection consists of mechanical, electric, hydraulic and other kinematic circuits through which movements are transmitted. Kinematic chains also serve to change the speeds and direction of movement of actuators with the help of appropriate mechanisms at a constant drive speed, for converting and summing movements, etc. Kinematic chains consist of separate links.

Kinematic connection of actuating links to each other, which determines only nature of actuating movement, is internal kinematic connection. The link between the motion source and the movable actuator determines the velocity characteristics of the latter and is an external kinematic link. At short distances between axes of shafts the transmission is performed by direct contact. Various gears are used for this purpose. Bevel gears are used to transmit rotation between crossing shafts, and worm, screw, cylindrical gears are used between crossing shafts. For the average distances between the shafts, a variety of belt and chain transmissions are widely used. Individual elements of kinematic chains are represented in diagrams by schematic symbols. The main kinematic parameter characterizing all types of mechanical transmissions of rotational motion is the ratio, that is, the ratio of the rotation frequency of the driven shaft to the rotation speed of the driving shaft.

From the main motion motors through the V-belt transmission with the diameter of the pulleys 140 and 268 mm, the speed box shaft I rotates, on which freely rotating gears are installed with the number of teeth z = 56 and z = 51 for direct rotation of the spindle (clockwise) and z = 50 for reverse rotation of the spindle (counterclockwise). Actuation of direct or reverse rotation of the spindle is performed by friction couplings Mf 1 and Mf 2. Shaft III receives two straight speeds of rotation through wheels z = 34 or z = 39. Further by means of gears z = 29, z = 21 or z = 38, coupling to one of the respective crowns z = 47, z = 55 or z = 38, forming a triple block, receives rotation of shaft IV. From this shaft, rotation can be transmitted directly to the spindle - through gears z = 60 or z = 30 to the block with z = 48, z = 60 or through shafts V and IV forming with gear wheels a bulkhead group. In this case, the movement is transmitted by gears z = 45 or z = 15 (on shaft IV), engaging with one of the rims of the block z = 45? z = 60 (on shaft V), and pairs of wheels 18/72 and 30/60. Depending on the gear options in the gearbox, 22 different spindle speeds can be obtained .

The movement of the caliper ensures that the tool is fed during the cutting of this movement either directly from the spindle or through a step increasing link located in the gearbox and having three gear ratios, and even through the reverse mechanism of the replacement wheels K/L, M/N, gearbox and apron gear mechanism. The reverse mechanism consists of gears z = 30, z = 25, z = 45 mounted on shafts VIII, IX and X. The feed box has two main kinematic chains for cutting in the first case inch and pitch, and in the second - metric and modular threads. The second kinematic chain passing through the couplings Mf 4 and Mf 5 is also used to transfer motion to the running roller, but with the coupling Mf 6 turned on. For cutting threads with increased accuracy and special movement on the lead screw is transmitted to the straight line, that is, the feed box is turned off, and the shafts XII, XVII and XVIII are interconnected using couplings Mf 3 and Mf 6. In these cases, the required step of moving the caliper is adjusted under the board of replaceable gears K, L, M, N of the guitar. To simplify the work on setting the machine to the specified speeds of spindle rotation and caliper supply, a table with mnemonic symbols of threads to be cut, control handles and numerical values of feed, speed and number of teeth of replaceable wheels is placed on the spindle head. Quick movements of the caliper are carried out from a separate electric motor through a belt gear rotating running roller.

On the basis of turning and screw-cutting machines, specialized machines are created designed to perform one operation. Such specialized machines are used in large-scale and mass production of the same type of parts.

Analysis of shortcomings of the existing machine layout

The disadvantage of the kinematic scheme of the machine is mechanical stepwise control of the speed of rotation, as well as mechanical stepwise switching of feeds in the feed box. The use of automatic boxes for switching speeds and supplies using electromagnetic couplings would significantly simplify the kinematic scheme of the machine.

Non-contact control of asynchronous motors can be introduced into the machine diagram, which would allow smooth control of the rotation speed of the electric drive. Add circuit breakers with combined disconnectors (current, heat and minimum voltage) to the machine diagram. The circuit breaker simultaneously replaces the input switch, fuse and thermal relays. Their use ensures when the protection is triggered, the disconnection of all three phases. Also, the circuit breaker could be installed instead of the input package switch S1, which, in addition to turning on the electrical part of the machine, can provide zero protection during power interruptions, protecting the machine from short circuits of current overloads arising in the shop network in the presence of a thermal disconnector. Replace fuse F3 and switch S3 with circuit breaker in the lighting circuit. An electromagnetic sliding clutch could be installed in the circuit to simplify the design of the feed box.

Peculiarities of electrical equipment of turning and screw-cutting machine UT16V

Three three-phase short-circuited asynchronous motors are installed on the machine. The following AC voltage values can be used on the machine:

power circuit 3 ~ 50 Hz, 220 V, 380 V;

control circuit ~ 50 Hz, 110 V;

local lighting circuit ~ 50 Hz, 24 V.

The electrical equipment of the machine is designed for connection to a three-phase AC network with a de-grounded or isolated neutral. In the left niche of the rear side of the bed, a limit switch is installed to limit the idling of the main drive. To illuminate the workplace, there is a lamp with a flexible rack of GHS - 1 type with a MO lamp (24 V, 40 V). On the carriage there is a push-button station S3, S4 for starting and stopping the main drive motor and a button for emergency disconnection of electrical equipment. A limit switch S8 is built into the apron handles to control the engine, move the carriage and caliper. Control cabinet is installed on rear wall of front head. On the front side of the control cabinet there are the following controls:

handle for switching on and off the input circuit breaker with maximum and independent disconnector for connection and disconnection from the supply network;

a white lens signal lamp indicating the on state of the lead-in switch;

switch for switching on and off the electric cooling pump;

load indicator showing the load of the motor of the main drive, having three scales: two white and black. White on the left shows underload of the machine, black - load from 85 to 100%, white on the right shows underload.

When connecting the machine, make sure that the voltage and frequency of the power supply network correspond to the electrical parameters of the machine specified in the table on the internal surface of the control cabinet door. The input of the earthing and power supply wires can be made both through the upper plane of the control cabinet and through the lower plane. When grounding the machine with a steel bus, a special bolt is used. Do not work with open terminal box and control cabinet. Motor protection of the main drive of the transmission mechanism, electric cooling pumps and transformers from short-circuit currents shall be carried out by circuit breakers and fuses. Engines are protected from long-term overloads by thermal relays. Zero protection of the electric motor is carried out by starter coils, which, when voltage decreases to 85% of the nominal voltage, automatically disconnect the electric motors from power supply.

Justification and selection of the control system

The performance of the machine depends on the correct selection of the control system. The machine control system has the following requirements:

1) safety and ease of control - achieved by placing the controls in easily accessible places so that the worker does not have to walk around the machine a lot;

2) the speed of control, that is, the less time should be spent on the control operation, the more often it is carried out;

3) the accuracy of the control system, which is set depending on the purpose of the system and the function performed by it.

Currently, mechanical, electrical, hydraulic, pneumatic devices are used in machine control systems.

Mechanical elements and automation tools are widely used to control working and auxiliary movements in machines - automatic machines and semi-automatic machines designed for large-scale and mass production of typical parts.

Hydraulic control is widely used in aggregate copying and other machines due to its simplicity, speed, smoothness of the movement of the hydraulic drive element, which reduces the vibration of the machine. Hydraulic systems also have disadvantages: connections between individual elements are carried out by means of levers and hoses, which complicates the design of machine tools; during operation in the hydraulic system, seals may be broken and a leak occurs; the machine constantly contains a large amount of oil, which must be periodically changed.

In recent years, the use of pneumatic control devices in machine tools has been continuously expanding. Pneumatic elements and systems are mostly used in combination with hydraulic or electrical elements. In such systems, the driving force is generated with compressed air, from hydraulic or electrical equipment that is used to control movement.

In machines, remote control is widely used when the control panel is located at a more or less significant distance from the controlled elements. Remote control systems can be electromechanical, electrohydraulic and other.

The most widely used electrical control systems for metal cutting machines. The use of electrical elements and control devices facilitates wide unification and standardization of machine units, which reduces its cost. Electrical automation of machines has significant advantages over all

other automation methods, providing easy operation and easy adjustment of the machine, thereby expanding the possibilities of creating and using machine tools. In some cases, the use of mixed control systems is effective, for example, hydraulics or pneumatics for performing power functions, and electrical devices for controlling them. Such control systems are called electro-hydraulic or electro-pneumatic. Low-voltage electric devices have been widely used in machine control systems and automatic lines: magnetic starters, contactors, voltage and current relays, electromagnets and electromagnetic couplings, track switches and switches, circuit breakers. The UT16V machine uses an electro-pneumatic control system in combination with a mechanical control system. Pneumatic equipment in the turning-screw-cutting machine serves to create an air cushion that facilitates movement of the rear head along the bed and prevents wear of guides. Pneumatic devices are mounted on the rear side of the machine. Electrical equipment of the machine is designed for connection to three-phase AC mains with de-grounded or isolated neutral (2), (3)

Requirements for electrical equipment of the UT16V lathe

The main requirement for the electric drive of the machine is the sufficient power of the motors driving the machine mechanism. The required power is achieved by the rational calculation and selection of the correct electric motor, and above all, it must be economically profitable and must satisfy the peculiarities of the technological process on said machine. It is also necessary to arrange wires and cables efficiently, which leads to a decrease in the mass of wires. Reliability of operation of electrical equipment and control system is achieved using protection devices. Observance of technical operation rules leads to safe operation of maintenance personnel on the machine. The requirements for protection devices are such as reliability, durability, simplicity of design, accuracy and safety of operation. In addition to the above listed requirements, it is necessary to periodically check the status of the starting and relay equipment. All electrical equipment parts shall be cleaned of dust and dirt. To avoid rust, the surface of the core joint with the starter anchor is periodically lubricated with machine oil with subsequent straining with dry cloth. During inspections of relay protection, special attention should be paid to reliable closure and opening of contact bridges.

During technical inspections, it is necessary to check the condition of the lead-in wires of the stator winding, clean the motors from contamination, and monitor the reliability of the grounding. During preventive inspections, the motors should be disassembled, internal and external surfaces should be cleaned and bearing lubrication should be replaced. Perform preventive inspection of circuit breakers at least once every six months, as well as after each shutdown in case of short circuit, including repeated. Correct fulfillment of the requirements for electrical equipment allows extending the machine life, ensuring the safety and reliability of the machine electrical equipment. (1), (3)

Current and

supply voltage selection

Currently, the three-phase AC system has become the most widespread. This is due to a number of reasons. Such a system makes it possible to use three-phase asynchronous motors with a short-circuited rotor, which are characterized by simplicity of design, maintenance, and cheapness. The AC system allows you to easily transform energy, which is important when distributing between consumers. In some cases, it is advisable to use a direct current system where huge and expensive electrical machines are not required. They are successfully replaced by semiconductor rectifiers that are small in size. The DC motor is used in cases where it is necessary to ensure a smooth control of the speed of rotation within wide limits, in addition, under severe operating conditions, at a high switching frequency or with high equipment responsibility. Electric drive control circuits are supplied with constant voltage. This solution is dictated by the fact that switching equipment operating at direct current is more reliable and durable. However, it is more expensive than equivalent AC equipment. When choosing the kind of current, the supply circuits of the control must be guided by both operational requirements and economic considerations. When choosing the value of the supply voltage, take into account the peculiarity of the operation of machines and the mechanism, as well as individual units

A voltage of 1120.150, 220.330 and 500 kV should be used to power large enterprises, and 110, 150 and 220 kV should be used at the first stages of these enterprises.

The 35 kV voltage can be used for full or partial in-plant distribution of electricity in the presence of powerful electric receivers, high voltage electric receivers and significantly remote from power sources, substations of small and medium power with a voltage of 35/0.4 kV.

20 kV should be used to power medium-capacity enterprises that are remote from power sources and do not have their own power plants, remote from substations of large enterprises, small enterprises and settlements connected to the CHP of the nearest enterprise.

10kV must be used for internal power distribution: in enterprises with powerful engines directly connected to the 10 kV network; in small and medium-power enterprises with no or few engines of 6 kV; in enterprises with a power plant. 6 kV voltage is used when a large number of receivers up to 6 kV are available at the enterprise; in the presence of its own power plant with generators for 6 kV.

In rooms with high danger and especially dangerous points of electric shock, use voltage not higher than 42V, obtained from lowering transformers. In rooms with particularly unfavorable power supply medium of portable lamps with filament lamps the voltage shall not be higher than 12V.

When selecting the value of the supply voltage, such requirements as that: the supplied voltage should not be excessively high (according to safety conditions) should be taken into account; economic considerations should be taken into account; small losses during voltage transfer to consumers. The three-phase alternating voltage system of 380/220V with a grounded neutral, which has been widely used for workshop networks, meets the above requirements.

Electrical Diagram Description

Circuit diagram is an electrical connection diagram made in an expanded form. It is the main diagram of the design of electrical equipment of the production mechanism and gives an overview of the electrical equipment of this mechanism, reflects the operation of the automatic drive and control system of the mechanism, serves as a source for drawing up connection diagrams. According to the schematic diagram, the correct electrical connections are checked during installation and adjustment. The quality of the schematic design depends on the clarity of the operation of the production mechanism, its performance and reliability in operation. The design types and technical data of electric motors, electromagnets, limit switches, contactors and relays are also specified in the process of drawing up the schematic diagram. In the schematic diagram, all elements of each electrical device, apparatus or instrument are shown separately and placed for the convenience of reading the circuit in various places of it, depending on the functions performed. For the model UT16V machine diagram, it is necessary to calculate its protection devices, such as fuses, starters with a thermal relay, transformer for local lighting, main circuit breaker, select button stations, limit switch and wires.

Three three-phase asynchronous motors are installed on the UT16V universal turning-and-turning machine. In the left niche of the rear side of the bed, a limit switch is installed to limit the idling of the main drive. During initial start-up of the machine by external inspection check reliability of grounding and quality of installation of electrical equipment. After inspection, check the action of locking devices. Check the accuracy of magnetic starters and relays actuation using manual controls. Drive of spindle and working feed of caliper is implemented from asynchronous short-circuited motor. Adjustment of spindle angular speed is performed by switching gears of speed box by means of handles, change of longitudinal and transverse feed of caliper - switching gears of feed box also by means of corresponding handles. For quick movements of the caliper, a separate asynchronous motor is used. Turning on and off the machine spindle, as well as its reversal, is carried out using a multi-disc friction clutch, which is controlled by two handles. The machine is energized by switching on the packet switch S1. The control circuits are powered through the TV separation transformer with a secondary voltage of 110V, which increases the reliability of the control devices. Start the electric motor by pressing S5 button, at that the circuit of K1 contactor coil is closed, setting it to self-energizing. Actuation of the spindle is performed by turning the friction clutch control handle upwards. If the pause in operation exceeds from 3 to 8 minutes, the contact of the time relay KV opens and contactor K1 loses power. The main motor is disconnected from the mains and stopped, which limits its operation in idle mode with a low cosetavalue and reduces energy loss. The motor of quick movements M2 is controlled by pressing the push button of the apron built into the handle and acting on the push-button switch S7. Start and stop of M3 pump motor is performed by switching of S2 package switch. The operation of the electric pump is blocked with the motor of the main drive M1, and its actuation is possible only after the contacts of the starter K1 are closed. The machine has local lighting. The HL lamp is powered by 36V voltage, from a separate transformer winding. In the lamp circuit are fuse F3 and switch S3. As one of the wires

the secondary circuit of local lighting at voltages of 12 and 36V usually uses a machine bed. Electric motors of the main drive of fast movements and the caliper of the electric cooling pump and transformer are protected from short-circuit current by automatic circuit breakers and fuses. Electric motors (except for motor M2) are protected against long-term overloads by thermal relay KK1, KK2. Zero protection of the machine electric circuit, which protects against spontaneous actuation of the electric drive when the electric power supply is restored after its sudden disconnection, is carried out by coils of magnetic starters. During installation, the machine shall be reliably grounded and connected to the common grounding system. The wires are inserted into the control cabinet from below through the holes. Input shall be made by 6mm 2 SGV wire for 220V mains voltage and 4mm 2 for all other voltages; black for linear and green-yellow for grounding.

Concept of estimates and types of estimates

All labor products in society have a value and are of the nature of goods. The cost of goods is determined by socially necessary labor costs, which include animal labor and live labor invested in the production of goods. According to the law of expanded production, live labor includes socially necessary and additional labor. The value expressed in cash is the price of the labour product.

In assembly production, pricing has some features in contrast to industrial production. They consist in a wide variety of construction products, dependence of cost values ​ ​ on local conditions, a significant length of the production cycle, participation in the installation of facilities of many specialized enterprises.

For this reason, uniform prices for products have not been distributed. Prices for products are determined by estimates made separately for each object and for each type of work.

The estimate is the calculation of costs for the entire volume of production.

The following types of estimates are distinguished: 1. Estimated is the calculation of costs for a newly mastered product or product; 2. Planned - calculation of production costs of individual types of goods and services for the planned period; 3. Actual - Estimate at the end of the planning period.

The comparison of planned and actual estimates allows you to more accurately determine production costs and draw up a plan of measures to reduce cost.

The related cost of electrical installation works consists of direct costs, overhead costs and planned savings.

Direct costs consist of the following elements: basic wages of workers; the cost of materials, structures and parts, taking into account the costs associated with their delivery from factory manufacturers; cost of operation of machines and mechanisms and other direct costs.

Overhead expenses include administrative and economic expenses, expenses for maintenance of workers and expenses for organization and execution of construction and installation works.

The costs of servicing workers include: additional wages of industrial workers; additional payment to the average earnings of young workers and students; social insurance contributions; health and safety costs; expenses related to housing and communal services provided by the organization.

Expenses for the organization and execution of installation works include: maintenance of the guard and fire department, maintenance of production equipment and equipment, maintenance of regulatory research stations and carrying out current measures to rationalize the production, improvement of installation sites, travel of high-skill installation workers for installation work, maintenance of groups of designers and estimators intended for work related to the organization and performance of installation works, etc.

In the estimates and price tags for electrical works, overhead costs are calculated either as a percentage of the amount of the main salary of workers, or as a percentage of the amount of direct costs.

The estimated cost of certain types of work is the price of products of specialized organizations performing this type of work.

The cost of installation works is a generalizing indicator of the production and economic activity of the organization and represents the cost of installation works expressed in cash form.

A large degree of reduction in the cost of installation works is achieved by using equipment, material, labor and financial resources in the production process and by a perfect method of managing production activities.

The insulation test of rotors, anchors and excitation circuits may be carried out by one person with an electrical safety group not lower than III, the insulation test of stators - at least two persons one of which must have a group not lower than IV, and the second - not lower than III.

When working with a megohmmeter, it is forbidden to touch the current-carrying parts to which it is attached. After completion of operation, it is necessary to remove residual charge from the equipment to be checked, by means of its short temporary grounding. Measurement by megohmmeter is prohibited during thunderstorms or at its approach .

Insulation shall be considered to be withstood by the high voltage test if no insulation disturbance has been observed by instrument readings or visual observation of the insulation surface.

Select Connection Scheme

All electrical devices, depending on the design, can have connecting clips either on the front or rear side and depending on the position of the clamps, the wire on the control panel can be made on the front or rear side of the apparatus. If we select front mounting, all connection wires must be laid on the front side of the control panel, which must be made of steel sheet, and sets of connection clamps must be placed on the same side of the panel. When selecting the rear mounting, the devices are located on the front side of the control panel made of a common plate tape or textolith, and the wires and sets of connection clamps on the rear side. After placing the electrical equipment of the machine, sketching the placement of the equipment and choosing how to connect the wires, we begin to design their wiring between the instrument clamps, that is, we develop a diagram of their connection. On the connection diagrams, all devices and other devices are depicted as non-separate elements. The connection diagrams reflect the actual location of the individual units and devices of the machine electrical equipment in the cabinets, on the control panel, as well as the method of connections between them.

The connection diagram is made according to the schematic electrical diagram and the layout of the electrical equipment, at the same time the same equipment symbols and markings as on the schematic diagram are used. When drawing up the connection diagram, follow the following requirements:

wires are connected only to terminals of electric machines, devices and sets of external terminals (terminals), which are produced by industry for nominal currents of 10, 25.60 and 200 A with voltage up to 500 V;

It is recommended that no more than two wires be connected to one connection terminal, and if there are more wires to be connected, intermediate clamps should be used;

it is absolutely not allowed to connect wires in addition to the connecting clamps, that is, by twisting or soldering;

in the aisles of one control panel, all wire splits between the sets should be made on the device clamps, without using intermediate clamps.

In the wire connection diagram, the wires coming from the sets of clamps or from the sets in the same direction can be depicted in two ways: either by line, or each wire can be shown separately. Currently, the first method has become widespread. Sometimes on the connection diagrams in the control circuits of the full image of the wiring lines between each other and the sets, a small wiring length is made, on which only the wiring direction is indicated by counter arrows. Near each pointer arrow, an "address" is placed - the symbol of the apparatus or clamp to which the second end of the connecting wire goes, and the wire number. The location of such wires is selected on the installation sheet. If the wire is to be connected to a set installed on another panel, the arrow must specify the number of the set and the number of the control panel to which the wire will be connected. Wiring from panels to those devices that are built into the electrical equipment cabinet separately is also noted: resistors, signal lamps, measuring devices and other electrical equipment.

Detachable electrical connections (device clamps and sets of connecting clamps) are shown on diagrams not crossed out by circles, and non-detachable connections of wires, wires from the control panel or from the device or connections obtained by soldering or cold pressing, on the connection diagram are shown by crossed out circle. The connection circuit is always based on the circuit diagram.

Electrical wiring of industrial mechanisms

Connection of all elements of the electrical equipment of the machine or production machine into a common circuit and power supply

current collectors are made using electrical wiring made in accordance with the general diagram of electrical equipment. These diagrams are made on the basis of the schematic electrical diagram and the layout of the electrical equipment on the machine. When compiling a general diagram, the same designations are used as on the schematic diagram. The equipment located in the electric box is usually surrounded by a common frame, and the wires going in the same direction are depicted in a common diagram with one bold line.

Electrical wiring of machines is carried out by wires and cables, mainly in polychlorovinyl insulation. According to the general process conditions for electrical wiring of machines and machines, copper wires with a cross section of at least 1 mm2 and less than 1 mm2 in the chains of amplifying devices can be used. It is allowed to use wire of 0.72 mm2 sections directly on machine tools, and 0.5 mm2 and 0.35 mm2 on panels. Wiring shall ensure reliability of operation of all electrical equipment, be convenient and easy to operate, and during installation harmoniously merge with the production mechanism. According to the design of the assembly, there are three types of postings: posting on panels and blocks, local posting and external posting .

Installation of local wiring with a circuit for protecting conductors from mechanical damage and harmful effects of dust, oil, emulsion is carried out in steel thin pipes so that the shape of the wiring does not deteriorate the appearance of the machine. The number of bends shall allow free sweeping and modification of wires. If a large number of bends are required, then the wiring is carried out in metal handles of thin-walled pipes. The wires in the pipes and in the hoses shall be one-piece wire connection by soldering or twisting; pipes are connected by means of reinforcement, tees of elbows, branching boxes. For every 7 to 10 wires of control circuits laid in a pipe or metal hose, one backup wire is added on a common branch and their numbering is indicated, according to the schematic diagram and it is mandatory to indicate the number of wires, their section, color. All ends of the wires connecting the clamps of individual devices and machines, during installation of the equipment must be marked in accordance with the numbering available on the connection diagram, schematic diagram. Wire markings are made using tags made of plastic, fibrils, the tins of which are indicated by the wire index. Tags on wires are fixed with cotter pins. In some cases, the use of tags is inconvenient, then pieces of white polychlorovinyl tube are put on the ends of the wires, which should fit tightly to the insulation of the wire. On tubes with special ink, wire conventions are applied. For the convenience of mounting and ensuring that a faulty wire is found, branching boxes in which clamp sets are located have been widely used in the wiring installation. To these clamps are connected on one side wires coming from electric machines and apparatus, and on the other side wires going to control panel located in electric cabinets. Wires to electrical equipment units located on movable parts of machine mechanisms are made by flexible wire in polychlorovinyl insulation, which are pulled in metal-hook rubber by armor hose or elastic tube. Wires are supplied to electrical equipment located on rotating parts of the machine by means of current wires. Electrical wiring on the panels of cabinets and niches is performed by rigid wires of PV, PR grades, with a copper core section of the load selected by current, but not less than 1 mm2, in circuits providing sufficient mechanical strength. In the niche, wiring is performed in steel pipes laid on the floor or foundation of the machine in special channels closed with heavy iron shields from the top. Power is supplied to the electric control cabinet from the shop network. In other cases, the machine is connected to the cable network of the workshop through channels in the floor or through walls with open wiring. Any type of open wiring is mounted in two stages: in the first, all preparatory and procurement work is carried out; in the second one, installation works are performed, pre-prepared electric wiring is laid along prepared routes, assembled and enlarged into units and units of electrical equipment are installed. Open wiring is labor-intensive, worsens the appearance of the room or workshop, creates inconvenience during repair and requires additional protection from harmful effects. Open wiring with insulated wires in pipelines is widely used.