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The use of frequency converters to control the speed of a lathe spindle, control the rotation speed of the main drive of a grinding machine, control the speed of the drawing line traction element, control the line for longitudinal and transverse cutting of sheet metal.

Job: Frequency converter 1 regulates the rotation speed of asynchronous motor 2 of the main drive of spindle 3. The system operates in a closed circuit with feedback depending on the rotation speed. The rotation speed is measured by pulse sensor 6. The operating mode of the variable frequency drive is set from the control panel 5. The cutter 4 smoothly moves from right to left along the rotating part.

Before the introduction of variable frequency drives, the rotation speed of the motor was constant, and the spindle speed could only be changed discretely using a gearbox.

Equipping processing machines with a frequency-controlled electric drive makes it possible to satisfy the most stringent and contradictory requirements imposed by the technology of processing various materials. The use of a variable frequency drive makes it easier to control the machine due to the ability to smoothly change the spindle speed without stopping it, and expand the speed range. The use of a gearbox and variable frequency drive allows you to optimally set the spindle speed and obtain maximum torque at low speeds.

Increasing the range of spindle rotation speed control to a value of 1:100 or more and thereby expanding the capabilities of the machine for processing parts made of various materials.

improving the quality of processing parts and reducing the number of cutting tool breakdowns due to precise maintenance of spindle rotation speed,

reducing the number of equipment breakdowns by reducing shock loads on the electric drive and mechanical transmission during startup and shutdown.

Problem to be solved: Direct control of the rotation speed of the grinding wheel to ensure the required quality of grinding of various materials.

Options: wheel rotation speed rpm, discrepancy between the wheel rotation speed leads to poor grinding quality. For example, grinding soft materials at high speed leads to “burning” of the surface, and the plastic melts.

Regulating the wheel rotation speed using a frequency converter allows you to:

expand the machine’s capabilities for processing various raw materials,

select the optimal wheel rotation speed to improve the quality of processing of each material.

Machine diagram. The workpiece 1 is fixed horizontally on the work table 2. The work table moves relative to the rotating circle using handles 3 and 4. The grinding wheel 8 is rotated by a high-speed electric motor 5 at the speed required for the given material. Regulation of the rotation speed is achieved using a frequency converter 6. The specified required speed is set from the control panel 7.

Drawing is widely used for the production of bar metal, wire, pipes and other metal products of constant cross-section. This is a continuous process of metal deformation by drawing blanks through one or more calibrated holes (dies) on drawing machines.

Job: The initial coil of wire is located on the unwinding device 1. Through rotating rollers 2, called descaling, the wire is fed into the installation for applying lubricant 3. Next, the wire is pulled through the die 4 of a tapering cross-section (shown below by the arrow).

Three or four turns of wire are laid on the drive drum of the drawing machine 7. The drum is driven by an asynchronous motor 6, which is controlled by a frequency converter 8. The tension force of the wire (torque on the drum shaft) is measured by a tension sensor 5. The feedback signal from the tension sensor is supplied to the input of the frequency converter. Thus, a closed circuit for controlling the torque on the shaft of the pulling drum is constructed.

The specified torque on the shaft is set on the front panel of the control cabinet 9. In this case, in the steady state of operation of the drawing mill, the linear speed of the wire at the exit from the die is maintained constant. From the output of the drawing machine, through the stacker 14, the wire is fed to the receiving reel 12 of the winding machine. The layer makes reciprocating movements and ensures uniform laying of the wire.

The rotation speed of the winding reel drive motor 13 is controlled by the frequency converter 10, so that as the winding diameter increases, the speed decreases. The winding diameter is determined by feedback sensor 11. The feedback sensor is a variable resistor, the resistance of which varies in proportion to the angle of rotation of the pressure roller.

The main purpose of using a frequency converter: expanding the capabilities of the drawing mill for processing metal of various strengths (hard and low-plasticity, difficult to deform, low-strength) and a wide range of sections. This is achieved by smoothly adjusting the drawing speed in the range of 1:1000 or more.

The use of a variable frequency drive also provides:

automation of the drawing mill operation under variable load due to coordinated regulation of drive electric motors,

elimination of wire breaks due to smooth starting and braking of the drawing machine drum,

improving the quality of finished products by accurately maintaining drawing speed.

The use of automated cutting lines becomes necessary almost always when working with sheet metal: manufacturing metal structures, metal profiles, body parts, etc. Frequency converters are part of the control systems of such lines.

In a typical cutting line, several converters can be installed: one of them 1 controls the electric drive 11 of the unwinding device 10, the other 2 controls the electric drive 6 of drawing the sheet, the third 3 controls the electric drive 4 of the winding device 5. General control is carried out from the panel of the control cabinet 9. For cutting metal 8 circular shears and 7 cross-cut shears are used.

In slitting lines, an electric drive with a frequency converter provides strip pulling and smooth starting/braking. The speed of the strip is maintained automatically by changing the loop in the loop pit 12 using speed sensors.

In cross-cutting lines (there is no winding device and converter 3, a receiving table 13 is installed in place of the loop hole), an electric drive with a frequency converter and a pulse sensor provides strip pulling, soft start-up, braking and precise stopping of the strip at the time of cutting.

The main purpose of using a frequency converter is to accurately stop the strip at the moment of cutting in cross-cutting lines and maintain a given strip speed in slitting lines.

The use of a variable frequency drive also provides:

provides high productivity of metal cutting lines.

reduction of labor costs and reduction of metal waste.

The cutting process is controlled centrally from the control cabinet. The operator sets the number and length of strips and sheets to be produced on the control panel.

The author of the blog “Simple Things” reviewed a recently purchased used TV 16 lathe. This is a small tabletop machine, all the main components are present on it, and even a few cutters are left in the kit.

Various machines and tools in this Chinese store.

This machine has automatic feed forward and backward, the gears by which the feed is regulated. The only thing is that there is no additional set of gears for cutting various threads. With this kit you can only slightly adjust the feed speed.

The machine is mounted on a massive metal base. Inside there is an electric three-phase motor, belts and pulleys that can be used to regulate the spindle speed. Powered by Chinese HT1000B. It can power motors up to 1.5 kW. That is, the frequency generator itself is powered by 220 volts of single-phase voltage, and at the output it produces a three-phase voltage of also 220 volts. Therefore, the master switched the engine according to the triangle circuit so that it would operate at 220 volts. 3 phases, 220 volts.

The previous owner reported that there was a minor breakdown. The regulator did not work, but after resoldering the variable resistor works. This frequency converter also has a function - the ability to install an additional variable resistor, it is remote, which allows you to directly control the speed. I also installed three buttons “forward”, “backward” and “stop”, that is, turn it on, add speed and the cartridge rotates in one direction. We stop it, then it rotates in the other direction and you can add speed.

Budget frequency generator for a lathe

The frequency generator surprised me because it turned out to be very budget-friendly compared to others on the Internet. I downloaded the instructions for it on the Internet, in English. But for those who have already connected frequency converters and programmed, it won’t be difficult to figure it out. There are various functions - braking and acceleration.

I installed a lamp, which is also turned on by a toggle switch. Moveable at 12 volts, it can be adjusted and illuminates the work area.

Checking the operation of the machine

Let's try to install some kind of workpiece and sharpen it. Let's see how the machine works. The machine initially vibrated a little and left a wave on the workpiece from the cutter. After sitting on the forums, I studied this issue, tightened the spindle nut, and the cone bearings in the headstock tightened. Apparently, this was the reason, the vibration stopped and now the machine sharpens quite normally. Let's install the 20th circle and see how the machine works. Turn on the feed, add speed. Such processing works. The owner is generally satisfied with the purchase, since for those who work in the workshop, the need for

We will show you a purchase that will help resolve an important issue. A year earlier, a lathe made in China was purchased. He had some problem. It was not possible to adjust the spindle speed. Therefore, adjustments were made to the design of the machine.

This is why it was purchased frequency converter. Using it, you can change the frequency of the current sent to the propulsion system of the machine. The device operates from a single-phase network with a voltage of 220 volts, and supplies three phases of 220 volts to the engine. 220 volt converter has a large number of control keys. How does a frequency generator work? Using a remote control and switches, it is capable of reversing, starting and shutting down the installation, and adjusting the speed of the engine unit.

Setting up the frequency converter

1. Having carried out the first setup, we have the opportunity to simply start the propulsion system of the benchtop lathe. Starting is carried out at a frequency of 10 hertz. Using a variable transistor, it is possible to change the speed of the propulsion system by increasing the current frequency to 400 hertz.
2. To change the direction of rotation of the lathe motor device using a converter, you must turn on the device. We turn on the toggle switch that changes the rotation of the torque of the propulsion system. At the same time, the engine began to rotate in the opposite direction.
3. Now let’s begin to consider the possibility of turning the engine of a desktop lathe using toggle switches, without using a rheostat. For this purpose, only the required speeds are turned on and off. When the frequency switch is switched to “on” mode, the device generates 10 hertz. The toggle switches are configured in such a way that when they are started, the current frequency increases by 5 hertz. As a result, we are able to adjust machine spindle speeds using a frequency drive without a mechanical transmission.

Operating conditions of the converter for a lathe

1. The converter is capable of operating in wide temperature ranges from +35 to -20 degrees. But, it should be borne in mind that the selection of the converter is carried out not according to power, but in accordance with the current of the propulsion system.
2. If the spindle operates at low speeds, then additional cooling elements should be installed on the motor, because the standard fan will not cope with the load. To maintain the required torque at low speeds, vector-type acceleration is used.
3. An encoder is installed on the electric motor, adjustment is made in a closed loop, and the torsional torque is stably maintained. From time to time, enterprises install asynchronous machines with encoder on lathes.

Electronic components of the frequency generator

Chinese factories already have the technology to produce motor units and software. For the factory version this is acceptable, but for domestic use it is too expensive.

New models of asynchronous type motor units have more complicated controls. When starting high-power asynchronous motors, high current overloads occur. Significant torque can lead to destruction of bearings and supports of the propulsion system. If the engine suddenly turns off, overvoltage and accidents in the electrical installation may occur. Therefore, when controlling electric motors, frequency converters are used.

We will show you our acquisition to resolve an important issue. A year ago we bought a Chinese lathe. It had the following problem. It is impossible to smoothly change the spindle speed. We decided to make changes to the design of the lathe.

Frequency converter instead of gearbox

For this purpose, a frequency converter was purchased. It allows you to change the frequency of the current supplied to the electric motor of the lathe. The device operates from a single-phase network with a voltage of 220 volts, and outputs it to an electric motor. This device has many control buttons. How does a frequency converter work? The device allows you to use a remote control for four switches in a row to reverse, turn the machine on and off, and change the engine rotation speed.

Why are there so many switches? Simplified ones can be done as follows. The device allows you to make multi-stage speeds. This device has five outputs, for different types of engine switching on and off, for different rotation speeds.

Setting up the frequency converter

1. The first setup we can do is simply turn on the motor of the benchtop lathe. The start occurs at a frequency of 10 hertz. Using a variable resistor, you can change the engine rotation speed by increasing the current frequency to 400 hertz.
2. If we need to change the direction of rotation of the lathe engine using a frequency converter, then first turn off the device. We turn on the toggle switch for changing the rotation of the engine torque. As a result, the engine began to rotate in the other direction. The frequency control can also change the direction of rotation of the engine.
3. Now let's consider the possibility of changing the rotation of the motor of a tabletop lathe using toggle switches, without using a rheostat. To do this, we only use turning on and off the corresponding speeds. To do this, we turn the frequency converter to the “on” position, the device produces 10 hertz. The toggle switches are configured so that when they are turned on, the current frequency increases by 5 hertz. As a result, we can control the spindle speed of a lathe using a frequency converter without a manual gearbox.

Operating conditions for a frequency generator for a lathe

1. The frequency converter operates in a wide temperature range from +35 to -20 degrees. However, you need to take into account that you need to choose a frequency converter based not on power, but on motor current. You cannot count on any engine operating frequency. Not every engine can operate at a frequency of 100 hertz, although the frequency generator produces them without problems. For example, a 0.55 kW motor at 2800 rpm can stop at a frequency of 75 hertz, but will work normally at 65 hertz. In theory, the engine can operate normally with small deviations from 50 hertz.
2. At low spindle speeds, you need to install additional cooling on the motor, since the original fan will not cope. To maintain sufficient torque at low speeds, vector acceleration is applied. Vector acceleration must be supported by the frequency converter.
3. You need to install an encoder on the electric motor, make adjustment settings in a closed loop, and always maintain torque. Sometimes, at the factory, synchronous motors with an encoder are installed on lathes. Chinese frequency manufacturers.

For the spindle, frequency control of the stator flux coupling is sufficient. This is called sensorless vector flow control. You always need to know how to configure a frequency converter, do a minimum of parameterization and start automatic adaptation. You can use the company's software to configure the controllers, as well as your own controller configuration programs.

Electronic filling of the frequency converter

Chinese manufacturers already know how to make engines and software. For the factory version this is normal, but for everyday use it is expensive.

Modern asynchronous motors have relatively complex controls. Starting a powerful asynchronous motor is associated with large current overloads. High torque can damage bearings and engine mounts. An abrupt shutdown of the engine leads to overvoltage and accidents in the electrical installation. Therefore, today good control systems for electric motors are frequency converters.

The output stages of such devices must be powerful. Insulated gate transistors solve this problem. The converter consists of a clock pulse generator, the frequency of which can be controlled. It is assembled using simple logical elements. In order to obtain a three-phase system, ten pulses were divided into a sequence of six pulses.

Information about the manufacturer of the Universal-3 (TSh3) lathe

The manufacturer of the Universal-3 table lathe is a plant founded in 1932.

Since 1964, the plant began manufacturing erosion machines using electrophysical and chemical processing methods. Almost all tool shops of various enterprises use electrical discharge machines and, in particular, models MA96, LF96F3, SK96F3, 4732F3M, 4733F3 and modern models SKE200F2, SKE200F3, SKE250F2, SKE250F3, SKE250F5.

Universal series table lathes

The first model of a benchtop lathe Station wagon with two round guides was developed by the organization ENIMS(Experimental Research Institute of Metal-Cutting Machine Tools). The machine was taken as a basis Unimat SL Austrian company EMCO (over 40 years, over 600 thousand machines of this model have been sold).

The Universal lathe was mass-produced at the enterprise Moscow machine tool plant StankoKonstruktsiya.

Since 1968, the StankoKonstruktsiya plant began producing table-top screw-cutting lathe Universal-2- a significantly improved Universal machine.

In the second half of the 80s, the design of the machine was significantly redesigned: starting with the model Universal-3 instead of two round guides, one of a larger diameter appeared in the middle of the bed and the headstock was no longer disconnected from the bed. Several factories began mass-producing the machine:

• Plant StankoKonstruktsiya: Universal, Universal-2, Universal-3 (TSh3), Universal-3m, Minitok(SKT100-01, SKT100-02, SKT100-03).
• Votkinsk Machine-Building Plant: Universal-V (TSh3-01)
• Vladimir Precision Equipment Plant: Universal-2
• Michurinsky plant Progress: TN-1, TN-1m
• Orion SKTB Nizhny Novgorod: TN-1m
• Penza Instrument-Making Plant(Federal State Unitary Enterprise FSPC "PO "Start" named after M.B. Protsenko") Penza: TD-180, TN-150

Universal-3 (TSh3) multifunctional table-top screw-cutting lathe. Purpose, scope

The Universal-3 machine replaced the previously produced Universal-2. The design of the latter was completely redesigned: two round guide frames were replaced by one more powerful one, the design of the headstock was completely changed, etc.

This machine is a “hobby” class machine and is intended for individual (household) use, i.e., due to its design features and technical characteristics, the machine is not intended for use in production.

The Universal-3 metal lathe is designed for processing workpieces made of metal, wood, and all types of plastic by turning.

The Universal-3 machine is a desktop lathe and is intended for all kinds of turning work:

• grooving and boring of external and internal cylindrical, shaped and conical surfaces
• drilling holes, chamfering
• boring of holes
• segment
• cutting metric threads with a cutter

The spindle of the Universal-3 lathe is a hollow steel part, with an internal hole of 15 mm for processing bar material, mounted on 2 roller bearings in the front and rear supports of the headstock.

The spindle receives 9 rotation speeds from a 370 W electric motor via a pulley drive.

A collet clamp with various internal holes can also be installed on the threaded end of the spindle.

Unlike the Universal-2 machine, the spindle cannot move along its axis.

The support with the cutter installed on it moves along the longitudinal guides by 215 mm and along the transverse guides by 90 mm.

A distinctive feature of the machine is its wide versatility and the possibility of readjustment using devices that allow you to perform the following work:

• drilling holes
• milling of planes, recesses, grooves, etc.
• grinding and polishing
• sharpening of various cutting and household tools
• sawing sheet material, slats, boards using a circular saw
• sawing along the contour using a jigsaw
• planing the planes of slats, bars and boards using a jointing device
• coiling of springs
• thread cutting with dies and taps with manual rotation of the spindle to others

With the help of simple devices made on a machine by an amateur himself, other work can be done.

The traditional visual layout of the machine in combination with a proven kinematic diagram allows you to confidently provide turning with accuracy class “H” over a long service life.

Compared to small-sized machines offered on the market, it is easy to operate, reliable and durable.

Thanks to the wide capabilities of the machine, using it at home is of great interest, and once you master labor skills, working on it will bring great pleasure.

The machine can also be widely used in school circles, clubs, pioneer palaces, pioneer camps, etc. for the manufacture of radio components, models of aircraft and ships, small original household items and decorations, individual toys, parts, games, etc.

The machine operates from a single-phase alternating current network with a voltage of 220 V and a frequency of 50 Hz.

The cast bed, rigid hardened guides and main body parts of the machine are made of high-quality modified cast iron with aging and ensure high accuracy of the machined part.

The Universal-3 machine has a device installed that allows changing the direction of movement of the support without changing the direction of rotation of the spindle and stopping it.

Accuracy standards for turning operations:

• Non-roundness of the processed sample-product with dimensions Ø30 x 125mm, no more than - 20
• Taper of the processed sample-product with dimensions Ø30 x 125mm, no more than - 30
• Roughness of the machined surface Ra, µm - 1.25 (at finishing conditions)

The technological capabilities of the Universal-3 machine can satisfy both a professional with the most diverse interests and an amateur.

Manufacturer of the machine Universal-3 - plant Machine Tool Design Moscow city.

• for drilling work - drills 2300-0181 (GOST 10902-77)
• for milling work - end mills 2220-0037 (GOST 17025-71): Cutting speed no more than 15 m/min.
• Surface grinding device: Cup grinding wheel 18 (see Fig. 4) is mounted on mandrel 15 using screw 19 and washer 20. Gaskets 21 made of cardboard are placed under the wheel and washer. The mandrel with the circle mounted on it is screwed onto the front end of the machine spindle. Then a protective ring 17 is put on the casing 14, located above the spindle, and screws 16 with washers are fixed on it through grooves designed to adjust the position of the protective ring relative to the grinding wheel.

Standard delivery set

The standard delivery set of the Universal-3 desktop machine includes:

Accessories:

1. Three-jaw chuck 7100-0001 with flange and ring assembly
2. Reverse jaw set and key for three-jaw chuck 7100-0001
3. Drill chuck with key 6-B10 or 10-B16 GOST 8522
4. Shank for drill chuck
5. Movable tool holder
6. Fixed tool holder
7. Center rotating
8. Center thrust 2 pcs.
9. Drive chuck
10. Mandrel with screws and clamp assembly (for boring work)
11. Collet F6
12. Collet F8
13. Surface grinding device
14. Vise
15. Sharpening device
16. Device for working with a circular saw
17. Leash for woodworking
18. Podruchnik
19. Jigsaw device
20. Screen
21. Chuck casing
22. Polyethylene oiler

Tool:

1. open-end wrench
2. Socket wrenches GOST11737
3. 7812-0373 40HFA N12x1 S=4
4. 7812-0374 40HFA N12x1 S=5
5. 7812-0375 40HFA N12x1 S=6
6. Chisel
7. Key for square S8
8. Socket wrench S10x13
9. Handle for key S10x13
10. Key for square S7
11. Right through cutter (high-speed steel)
12. Right through cutter with carbide plate
13. Scoring cutter (high-speed steel)
14. Boring cutter (high-speed steel)
15. Cutting cutter (high-speed steel) 2 pcs.
16. External thread cutter (high-speed steel)
17. Internal thread cutter (high-speed steel)
18. Circular saw 3420-0356 GOST 980-80
19. Jigsaw L=125 mm. TU 205.07.359-81 5 pcs.
20. Twist drill Ø6.0 GOST 10902
21. End mill with cylindrical shank Ø6.0 GOST 17025

Dimensions of the working space of the Universal-3 lathe. Caliper sketch

Dimensions of the working space of the Universal-3 machine. Caliper sketch

Drawing of the spindle of the Universal-3 screw-cutting lathe

Photo of the end of the spindle of the Universal-3 lathe

List of components of the Universal-3 turning machine

1. drive unit
2. bed
3. spindle head
4. caliper
5. tailstock
6. electrical box

List of controls for the Universal-3 screw-cutting lathe

1. feed movement control handle (turning on mechanical longitudinal feed of the caliper to the left, right and turning it off)
2. main movement control handle (turning on forward rotation of the spindle, stopping and turning on reverse rotation)
3. handwheel for transverse caliper movement
4. toolholder movement handwheel
5. quill clamp handle
6. quill movement handwheel
7. handwheel for longitudinal movement of the caliper
8. button to turn off the power to the electrical equipment of the machine (red)
9. power button for the electrical equipment of the machine (black)

Design and operation of the Universal-3 lathe

A hollow cylindrical guide is fixed to the machine bed. It is the common base for the main components of the machine: spindle head, caliper, tailstock. Another common base for these units is the flat bed guide.

In the front part of the frame, under the casing, there is a lead screw for longitudinal movement of the caliper.

A bracket is installed on the left wall of the headstock. The electric motor driving the machine is mounted on it.

Under the casing covering the bracket, there are spindle rotation drive pulleys and a feed drive mechanism.

Additional accessories for the Universal-3 multifunctional lathe. Setting up the machine for different types of processing

The machine is supplied in a lathe version. The additional accessories included in the delivery set (see Table 7) are used to implement other versions of the machine with the help of simple changeovers: milling and drilling, grinding, jointing, etc.

The design of additional accessories is described below and methods for setting them up for various types of processing are given.

Tool holders

The delivery set includes two tool holders: movable and fixed.

Using a movable tool holder mounted on a carriage, conical surfaces can be processed. The fixed tool holder is attached to the slide of the caliper using a screw and a block that fits into one of the T-shaped grooves of the slide. There are two screws in the carriage, which, using the same crackers, secure the carriage to the caliper slider.

In general, the carriage can be installed in any of the grooves of the caliper slide in accordance with the adjustment requirements.

To process conical surfaces, the carriage should be installed on the slider so that the initial zero stroke of the carriage scale coincides with the mark on the left end of the slider. This installation is carried out using one screw in the base of the carriage, which is screwed into a threaded hole specially provided for this purpose, located on the upper plane of the slide between two T-shaped slots. The carriage scale division is 1°.

ATTENTION! After turning the carriage to the required angle, it is necessary, in order to avoid an accident, to securely fix it with a fastening screw, as described above.

Collet clamp

The clamp consists of a collet, a nut and a ring; the collet is inserted into the conical hole of the spindle, and the nut is screwed onto the spindle along the thread. With the help of this nut in the collet, moving along its axis, the workpiece or cutting tool inserted into its internal cylindrical hole is clamped.

Milling and drilling device

The device (Fig. 4) is a rack 3, along the guides of which the table 4 moves. The movement is carried out by rotation of the handwheel I, rigidly connected to the lead screw 2. The workpiece is attached to the table with clamps 11 using pins 10, nuts 9, screws 8 and crackers 7, included in the T-shaped slots of the table. In order to set up the machine for milling or drilling work, it is necessary to secure the stand to the machine support using strips 6 and screws 5, as shown in Fig. 4.

The end mill or drill is secured in a collet clamp or in a special drill chuck 12 included in the delivery kit.

The chuck 12 is connected to the spindle using a special shank 13, also included in the delivery set.

In addition to clamps, a vice can be used to secure the workpiece, which is fastened with screws using crackers to the table of the milling and drilling device. The fixed jaw of the vice has two prismatic grooves that allow you to conveniently fasten cylindrical parts.

Kinematic diagram of the Universal-3 lathe

Description of the kinematic diagram of the Universal-3 screw-cutting lathe

Main drive chain

In this circuit, the spindle rotates from electric motor 3 through a V-belt drive (see Fig. 3). There are 9 operating spindle speeds.

Two stages (200 and 300 rpm) can be obtained if pulley 13, rigidly seated on the electric motor shaft, is connected by a belt to intermediate pulley 1, and that, in turn, along stream “a” - with pulley 2, freely rotating relative to the electric motor shaft . From pulley 2 along one of two free streams - “b” or “c” - rotation is transmitted directly to pulley 9, rigidly connected to the spindle.

One stage (650 rpm) is obtained by transmitting rotation from pulley 13 directly to pulley 9, bypassing intermediate pulleys 1 and 2.

Two more stages (525 and 1000 rpm) can be obtained if a replacement pulley 12 is put on pulley 13 so that the end on which there are cams faces outward. From pulley 12, as in the first case, rotation is transmitted to intermediate pulley 1, and from it along stream “b” to pulley 2, which transmits rotation to pulley 9 along streams “a” or “c”.

The remaining four stages (1200, 1700, 2800 and 3200 rpm) are obtained if the electric motor shaft is connected to pulley 2 through pulley 12 using cams located at one of the ends of the latter. Now, along any of the four streams, rotation can be transferred to pulley 9.

Note: The 1200 rpm stage can be obtained without connecting the motor shaft to pulley 2.

Feed drive chain

The caliper is moved to the right and left using lead screw 14.

Rotation is transmitted to the lead screw directly from the spindle by a gear II rigidly attached to it.

Through gear 10, rotation is transmitted to gears 8 and A, then to the intermediate roller 5. There are two options for transmitting rotation to this roller: the first option (indicated by number I in the diagram) - through a block of gear wheels B-B and wheel D, and the second (indicated by number II in the diagram) - through gears B and C.

The first option is used for feeding during normal turning, the second - when cutting threads. A gear 6 is rigidly connected to the roller 5. From this wheel to the wheel 7, mounted on the left end of the lead screw, rotation can be transmitted either through a pair of gears 15 and 16 - and then the caliper will move to the left, or through the gear 17, which will ensure moving the caliper to the right. All three wheels (15, 16 and 17) are mounted on the rotating device 4 (see D-D) and are in constant engagement with the gear wheel 6 (central). Thus, it is possible to move the caliper both to the right and to the left with the same direction of spindle rotation.

It is also possible to disable the support feed without stopping the spindle rotation. This is ensured by disengaging gears II and 10 using the same rotary device 4 and spring 18.

ATTENTION! To avoid breaking the gears of the feed drive chain, switching on and switching the direction of movement of the support should be done with the spindle not rotating.

The movement of the tailstock quill and the transverse movement of the caliper are carried out by handwheels through the corresponding screw pairs, as shown in the kinematic diagram.

Electrical equipment of the Universal-3 lathe. General information

According to the method of protection against electric shock, the electrical equipment of the machine belongs to class I, i.e. has working insulation, an element for grounding and a wire with a grounding conductor for connection to the power source and grounding.

The basic electrical diagram of the machine is shown in Fig. 14, the list of electrical equipment elements is in Table 4. Electrical equipment is located in a separate box (see Fig. 1, item 6). The box is closed with a lid. The cover is secured with two screws, one screw is located in the center of the cover under the rubber mat, the other secures the cover to the frame, ensuring the cover is grounded.

Description of the operation of the electrical circuit of the Universal-3 lathe

Electrical equipment is powered from a single-phase alternating current network with a voltage of 220 V and a frequency of 50 Hz.

Starting and stopping the electric motor is carried out using the KV relay (see Fig. 14), which is controlled by the SB2 (start) and SB1 (stop) buttons. When starting, the KV relay turns on and becomes self-powered, connecting the electric motor to the network with its contacts and providing zero protection, i.e. turning off the electric motor when there is no voltage in the network. The electric motor is protected from overload by the starting protection relay A, which breaks the starting circuit, which turns off the KV relay. Restarting is possible only after 15-50 s, i.e. after the thermal protection elements of the start-up relay A return to their original position.

When starting the electric motor, its starting torque increases due to the connection of the starting capacitor C1 by the contacts of the start-protective relay A in parallel with the running capacitor C2. After the electric motor accelerates and the starting current decreases, capacitor C1 is turned off.

Reversing the electric motor is carried out using the switch SA, which, with the middle (vertical) position of the handle, ensures that the electric motor is turned off, i.e. it stops even when the KV relay is turned on. The handle should be left in a neutral position

Screw-cutting lathe Universal-3. Video

A Universal-3 machine is shown in which the capacitor block and starting relay are replaced by a frequency converter.

On the plus side, smooth adjustment of speed (from hundreds to about 4000).

The downside is low torque at low speeds.

Technical characteristics of the Universal-3 machine