RU76593U1 - DEVICE FOR ELECTROEROSION ALLOYING - Google Patents

Abstract

The utility model relates to electrophysical processing methods, in particular to installations for electroerosive alloying of cutting tools, die tooling and machine parts.

The technical result of the utility model is to improve the quality of electroerosive alloying of the surface of parts.

The technical result is achieved due to the device for electroerosive alloying, comprising a fixed body with a magnetic circuit and a coil and a moving part consisting of an electrode holder with a coil connected to a current or voltage sensor at the spark gap through a control unit, according to a utility model, an optothyristor module is additionally introduced into the device, made in the form of two optothyristors and a relay element, the relay element at the input connected to the voltage sensor, and the output connected to the opt Hristor module, which in turn is connected to the control unit.

Description

The utility model relates to electrophysical processing methods, in particular to electrospark alloying of cutting tools, die tools and machine parts.

A device is known for electroerosive alloying, in which an electromagnetic vibrator transmits vibration to an electrode fixed in a hinge. The mandrel, with the opposite permanent magnets mounted on it, is rotated by an electric motor using a pulley and a transmission element. In this case, the magnetic field shifts the free end of the electrode by an amount not exceeding the diameter of the electrode, which is ensured by the hinge design. At the time of discharge, the magnetic field of the permanent magnets displaces the melt from the point of contact of the electrode and distributes it over the surface to be treated. Having come into contact with the treated surface, the electrode makes a reciprocating and rotational movement and under the influence of electric discharges, the process of applying electrode material to the hardened surface occurs [1].

The disadvantage of this device is the lack of continuity of the applied coating and low productivity of the installation.

A device for electrical discharge machining is known, in which a fixed housing with a magnetic circuit and a coil and a movable part consisting of an electrode holder with a coil connected to a current or voltage sensor on the spark gap through a control unit are used to automatically maintain the distance between the electrodes [2]. The disadvantage of this device is that the movable part is an electromagnetic damper, because the eddy currents arising in it during movement in a magnetic field create significant reactions that inhibit the sharp movements of the moving part. This affects the quality of the coating and reduces the performance of the installation.

A device is known that contains a power source, a vibrator and a generator, the electrical circuit of which contains a storage capacitance, an electric charging key, made on the basis of two transistors and a transistor module, control elements

a transistor switch, a discharge thyristor with its controls, a synchronization unit of a vibrator and a pulse generator [3]. The main disadvantages of the known device are the low reliability and stability, high specific energy consumption for the alloying process, low productivity of the device.

A device for spark hardening is known, comprising a transformer connected to the rectifier via a mode switch, the output of the rectifier is connected to resistor current limiters, which in turn are connected to storage capacitors and a processing electrode. The workpiece is connected with a working inductor and a rectifier, an electromagnetic vibrator coil is connected in parallel with the working inductor [4]. The disadvantage of this device is the low productivity due to overheating of the hardening electrode and the low frequency of spark discharges, which reduces the continuity and quality of the coating.

The closest technical solution to the claimed utility model is a device containing a fixed part - a body with a magnetic circuit and a coil and a moving part consisting of an electrode holder with a coil connected to a current and voltage sensor on the spark gap through the control unit [5]. The electrode fixed in the electrode holder interacts with the part, and the duration of the contact of the electrode with the part is controlled by the short circuit current flowing through the feedback solenoid. To prevent overheating, the electrode is constantly blown with compressed air.

However, this device has several disadvantages:

- low productivity of the device due to the use of rod electrodes of small diameter;

- the reinforcing layer is obtained with insufficient thickness;

- high energy consumption for the alloying process;

- low quality of the alloyed surface (coating continuity not higher than 80%) due to the inability to control the frequency and amplitude of vibration of the electrode tool.

The technical result of the utility model is to improve the quality of electroerosive alloying of the surface of parts.

The technical result is achieved by means of a device for electroerosive alloying, comprising a fixed body with a magnetic circuit and a coil and a moving part consisting of an electrode holder with a coil connected to a current sensor or

voltage at the spark gap through the control unit, according to a utility model, an opto-thyristor module made in the form of two opto-thyristors and a relay element is additionally introduced into the device, the relay element being connected to a voltage sensor at the input and connected to an opto-thyristor module, which in turn is connected to the control unit.

The proposed device is illustrated by drawings:

figure 1 - shows the mechanical components of the device,

figure 2 - shows the electrical functional diagram of the device.

The device has a fixed housing 1 with a magnetic circuit 2 and a coil 3, as well as a movable part 4, consisting of an electrode holder 5 and a coil 6. An electrode 15 mounted in an electrode holder 5 interacts with a part 16. As shown in FIG. 2, the movable coil 6 and fixed 3 are connected to power supplies 7 and 8, and power amplifier 9. Power supplies 7, 8, coils 3 and 6, and power amplifier 9 form a control unit 17. The input of power amplifier 9 is connected to voltage sensor 13 through a relay element 11 and an opto-thyristor module 10 completed and two optothyristors. The spark gap 12 is included in the power supply circuit technological current 14.

The device operates as follows.

When the device is connected to the network 14, the voltage is supplied to the output of the power source through the voltage sensor 13 to the input circuit of the opto-thyristor module 10, power amplifier 9 to the working electrode 15. In this case, the first opto-thyristor 19 opens and the second opto-thyristor 20, due to the presence of a differentiating circuit, remains closed. When the electrode 15 is closed to the part 16, the opto-thyristor 20 opens, which leads to the preset of timers, at the inputs of which a high level voltage is set. The opto-thyristor 19 is closed, and the opto-thyristor 20 remains in its original position.

When the working electrode 15 is separated from the part 16, the optothyristor 20 closes, the timers go into delay mode.

At the initial moment, the electrode 15 lies on the part 16 and the voltage at the input of the voltage sensor 13 is zero. In this case, a current flows through the movable coil 6, included at the output of the power amplifier 9. As a result of the interaction of the magnetic fields of the movable coil 6 and the stationary coil 3, powered by power supply units 7 and 8,

there is a magnetic force pulling the movable coil 6 together with the electrode holder 5. This leads to the separation of the electrode 15 from the part 16.

At this moment, the voltage at the input of the voltage sensor 13 increases and reaches the response voltage of the relay element 11. This causes a change in the direction of current flow in the movable coil 6, and the electrode holder 5 begins to move to the surface of the part 16.

When the electrode approaches the part to a distance of several tens of micrometers, the field strength reaches values at which an electric discharge occurs. At the moment the electrode touches the part, a small droplet of the deposited metal of the electrode is formed. Since the electrode is in constant rotation, grinding of this droplet takes place and it acquires an elongated shape. The voltage on the coils 3 and 6 is regulated by a potentiometer 18 in a wide range. The regulating element is the opto-thyristor module 10. The voltage is adjusted by changing the phase angle φ, at which the key of the opto-thyristor module 10 is unlocked when the voltage passes through "0". The storage capacitors are charged to a voltage determined by the position of the potentiometer 18.

In the future, the process is repeated, while there are constant oscillations of the electrode, the frequency of which is determined by the mass of the moving parts and the characteristics of the power amplifier. The subsequent closure of the electrode to the part causes the discharge of the storage capacity and mass transfer of the electrode material to the workpiece.

At the moment of contact of the electrode with the part, large short-circuit currents occur and the electrode begins to heat up, and if cooling is not performed, the electrode may become hot and droplets of the electrode material will stick to the part.

In addition, the heated electrode is oxidized due to interaction with oxygen in the air, which leads to rapid electrode wear.

To eliminate this drawback, it is proposed to perform electrode cooling with a cooler. As a cooler use compressed air or neutral gas. As the electrode material, hard alloys, high carbon alloys of iron or graphite are used.

For effective cooling, the electrode is made tubular and the cooler is fed into the inside of the electrode.

The proposed device allows you to automate

electroerosive alloying of complex-profile surfaces, which increases processing productivity and quality of hardening.

An example of a specific implementation of the device

The cutting knife of a woodworking machine, having the form of a narrow rectangular plate with a thickness of 4 mm and with dimensions of 50 x 400 mm, was subject to processing. The knife plate was made of ordinary carbon steel. A large surface of the knife was subjected to EDM, starting from the cutting edge over the entire length of the insert and with a width equal to half the width of the insert.

Electroerosive alloying was carried out with VK8 alloy with the following parameters:

- the speed of movement of the electrode tool, mm / sec. - one - supply voltage, V (50 Hz) - 220 ± 20 - power consumption, kVA - 2.2 - short circuit current, amperes - 8.5 - capacitance of capacitors, microfarad  - 950 - open circuit voltage, volt - 90 - diameter of the hollow electrode, mm - 8 - electrode material - VK8 - processing speed, cm ² / min - up to 5.5 - pulse repetition rate, Hz - 60 - cooler - compressed air

The technical result is the quality of the coating:

- thickness, mm -0.25 - continuity,% -97 - wear rate, mg / km -11.4 - surface roughness, Ra μm -4.1

Using a microscope of the MPB-2 type with a 24x magnification, it was established that the entire surface had a uniform electroerosive coating, no gaps were observed between the individual sections. If necessary, alloying can be repeated by applying the 2nd reinforcing layer.

The operational resistance of the processed woodworking knives depended on the material of the electrodes and increased by 1.5-2.5 times.

The use of the proposed device for electrospark alloying allows to increase the thickness of the alloyed layer,

increase the continuity of the coating, its adhesion to the base metal and increase the productivity of the process. In addition, the device allows you to evenly cover the alloying layer of flat, cylindrical and complex surfaces.

Thus, the claimed technical solution fully fulfills the task.

The claimed technical solution is not known in the Russian Federation and abroad and meets the requirements of the criterion of "novelty."

The technical solution can be implemented industrially in mass production using well-known technical means, technologies and materials and meets the requirements of the criterion of "industrial applicability".

References

1. A.S. 1609564, V23H 9/00, publ. in bull. No. 44, 1990

2. A.S. 1627353, V23H 9/00, publ. in bull. No.6, 1991

3. Installation of Elitron-22, passport AIIZ. 299.157. PS, Chisinau, 1986.

4. P-2171162, V23H 7/04, publ. 07/27/2001

5 Sex Model No. 2529, B 23H 7/18, publ. in bull. No. 8, 08.16.1996

Claims (1)

A device for electroerosive alloying containing a power source, storage capacitors, a fixed body with a magnetic circuit and a coil and a moving part consisting of an electrode holder with a coil connected to a voltage sensor at the spark gap through a control unit, characterized in that the opto-thyristor module is additionally introduced into the device, made of two optothyristors, and a relay element, the relay element at the input connected to the voltage sensor, and the output connected to the opto-thyristor module, which, in turn, is connected to the control unit.