SU1750879A1 - Method of electroerosive strengthening of part surfaces - Google Patents

Abstract

Usage: EDM hardening of the internal surfaces of parts such as pipes. SUMMARY OF THE INVENTION: The workpiece surface (pipes) is insulated from the environment with covers. An electrode holder with an electrode is inserted into the cavity of the pipe through a sealed hole in one of the caps. An inert gas — argon — is fed into the cavity through an electrode holder channel. Hardening is carried out at an excess pressure of argon in the tube cavity in the range of 0.005-0.025 MPa. Details set the rotation, the electrode - the vibration and movement relative to the part. Detail and the electrode is connected to the source of technological current. 1 ill., 1 tab.

Description

The invention relates to electrophysical and electrochemical processing methods and can be used for electroerosive hardening of the inner surfaces of pipe-type parts.

The aim of the invention is to increase productivity and improve the quality of the coating while hardening the inner surfaces of pipe-like parts by choosing the optimal pressure of an inert gas.

The drawing shows a diagram of the device for implementing the method.

The treated surface of the part (pipe) 1 is insulated from the surrounding space with the help of covers 2 and 3 with rubber gaskets 4. To insert the electrode holder 5, representing a hollow tube, a rubber membrane 6 is installed in the cover 3 6. The overpressure is determined by a MIT 7 gauge 1218 TU 25.03.1481-77. Which is through a channel with a reverse

the valve 8 in the lid 3 is connected with the internal cavity of the pipe. The pressure is controlled during operation by the safety valve 9. The part 1 is fixed in the three-jaw chuck 10 of the lathe. An electrode holder with an electrode 11 is attached to the vibrator 12 of the Elitron 50 installation, which is mounted on a lathe support. Current is supplied to the electrode through a vibrator, to the part through a cartridge (not shown).

The inner surface of the part is strengthened as follows.

The part 1 with the cover 2 installed on it with the built-in safety valve 9 is fixed in the cartridge 10. The vibrator 12 with the electric holder 5 attached to it is mounted on the machine caliper. The electrode holder 5 is then passed through a hole in the rubber membrane 6 installed in the cover 3, and the electrode 11 and the rubber hose are attached to the electrode holder, ensuring

SP

about

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The inert gas supply from the gearbox. After that, the cover 3 is attached to the part 1. Before starting the hardening, a pressure gauge 7 is screwed into the cover 3 and the flow rate of the inert gas is controlled through the reducer. The pressure gauge 7 is then removed and the part is machined as the spindle rotates and the vibrator 12 moves in translation.

The optimum overpressure in the range of 0.005 to 0.025 MPa has been established experimentally for pipes made of various materials. The lower limit of 0.005 MPa due to the need to produce processing in argon. At such a minimum pressure, air is expelled from the pipe cavity, which makes it possible to use the simplest technical solutions for insulating the inner surface.

Creating an overpressure in the cavity of the pipe of more than 0.025 MPa is reflected in the quality of the coating and the productivity of the process. The coating becomes more porous, its roughness increases. Performance decreases. This is related both to the change in the potential difference between the electrodes (it increases with increasing pressure due to an increase in the dielectric constant of the gas) and to the change in the thermal properties of the interelectrode gap.

Example. The method was used for electrical erosion hardening of pipes made of steel 40X.

Before coating, the internal surface of the tubes was processed by scanning.

to get the diameter

+ 0.02Q 23mm and

+ 0,033 roughness of R and 1.25 microns.

For eroding hardening

the Elitron setting was used - 50. The pipe was fixed on the spindle of the 16K20 lathe. The rotational speed of the spindle with the pipe was 16 rpm.

when the longitudinal movement of the vibrator mounted on the caliper 0.15 mm / Rev.

Hardening was performed with chromium during the operation of the electric pulse generator in the following mode: working force 7

A, the no-load voltage is 80 V, the storage capacitor capacitance is 540 µF.

The treatment was carried out with an excess pressure in the pipe of 0.004; 0,005; 0.01;

0.025 and 0.026 MPa. After the treatment, the diameter of the hole was measured, then the pipe was cut and the integrity and roughness of the samples were checked. By changing the diameter of the hole judged on the thickness of the applied layer.

The measurement results are shown in the table.

Claims (1)

Claims The method of electroerosive hardening of parts surfaces in argon, in which the surface to be treated is covered with a protective element, providing the introduction of the electrode-tool and the gas supply into the working area, and in order to improve the performance and improve the quality of the coating during hardening surfaces of the parts like pipes, the protective element are made in the form of caps on the ends of the pipe, and hardening is carried out with an excess pressure of argon in the cavity of the pipe of 0.005-0.025 MPa.