RU2768409C1 - Method of protection against short circuits during electrochemical sizing - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to machine building, in particular to electrochemical dimensional processing of metals and alloys with cyclic processing mode, and is intended for protection against short circuits. Method of protection against short circuits during electrochemical dimensional processing of workpiece from metals and alloys with creation of synchronous forced oscillations of electrode includes approaching the electrode to the workpiece prior to said processing and monitoring the subsequent passage of the contacts. After contact with the workpiece, the electrode is withdrawn from the workpiece to the specified interelectrode gap, and at this time the passage of contacts is monitored. In case of contact of the electrode with the workpiece, the delay time is counted, which corresponds to the double oscillation period of the electrode, and continue to withdraw electrode to specified interelectrode gap, and after the delay time is over and the electrode reaches the preset interelectrode gap, the electrode vibration amplitude is measured and processing is started provided that the measured electrode vibration amplitude complies with the specified allowable vibration limits.

EFFECT: reduction of number of short circuits and reduction of number of rejects during production of parts by method of electrochemical processing.

1 cl, 3 dwg

Description

The invention relates to the field of mechanical engineering, namely, electrochemical dimensional processing (ECM) of metals and alloys with a cyclic processing mode, with the creation of synchronous forced oscillations of the electrode, and is intended for protection against short circuits.

A known method of protection against short circuits during electrochemical processing, in which the current value of the derivative of the probabilistic characteristic of high-frequency current surges is continuously determined, compared with its initial value and, depending on their difference, a signal is generated to turn off the current source (description of the invention to the USSR author's certificate No. 1052359 Method of protection against short circuits during electrochemical processing, V23R 1/14, published 11/07/1983).

There is also known a method of protection against short circuits during electrochemical dimensional processing, according to which the average value of current and voltage is continuously monitored, their difference is determined and the voltage across the electrode gap is adjusted so that this difference remains constant, and in the event of disproportionate high-frequency changes, a signal is issued about the onset short circuit (description of the invention to the author's certificate of the USSR No. 1288005 Method of protection against short circuit during electrochemical dimensional processing, V23N 7/18, publ. 02/07/198).

The disadvantages of the known methods are the low reliability and stability of the protection response, since under industrial interference conditions, when electrochemical processing is carried out with high-current pulses with steep fronts, increasing the sensitivity of the devices leads to an increase in the number of false alarms of the protection, and reducing the sensitivity makes the protection ineffective.

Closest to the proposed is a method of protection against short circuits during electrochemical dimensional processing with the creation of forced oscillations of the electrode, in which before processing, the electrodes are brought closer to contact with the workpiece, the passage of contacts is monitored for a given delay time, the electrode is removed from the workpiece to a given interelectrode gap and allow processing (description of the invention to the patent RU 2198075 Method of protection against short circuits during electrochemical dimensional processing, B23H 3/02, publ. 10.02.2003. Bull.4).

The number of contacts during palpation depends not only on the pressing force, but also on the rigidity of the workpiece and the moment the electrode-tool starts to come out of contact with the workpiece. The contact method, or the “feeling” method, remains the most reliable and accurate method for setting the interelectrode gap (Equipment for dimensional electrochemical processing of machine parts. Edited by Sedykin F.V. M .: Mashinostroenie 1990, p. 124, 238- 244), but not taking into account the “bounce” of the contact when retracting to the interelectrode gap can significantly reduce its value, which leads to short circuits between the tool electrode and the workpiece.

The technical objective of the invention is to create a method of protection against short circuits during electrochemical dimensional processing, which allows maintaining the value of the interelectrode gap by taking into account the "bounce" of the contacts when the electrode is retracted.

The technical result of the invention is to reduce the number of short circuits and reduce the number of defects in the production of parts by electrochemical processing.

The technical result is achieved by the fact that in the method of protection against short circuits during electrochemical dimensional processing with the creation of forced oscillations of the electrode, in which, before the start of processing, the electrodes are brought closer to contact with the workpiece, the passage of contacts is monitored for a given delay time, the electrode is removed from the workpiece to a given interelectrode gap and allow processing, in contrast to the known one, after contact with the workpiece, the electrode is removed from the workpiece to a given interelectrode gap, during which the passage of contacts is monitored, while in the case of contact between the electrode and the workpiece, the delay time countdown begins and the electrode withdrawal continues, and processing is allowed after the end of the delay time and reaching the specified electrode gap, provided that the measured amplitude of the vibration of the electrode does not go beyond the allowable limits.

The method is illustrated in Fig., which shows:

fig. 1 - block diagram of the algorithm of the proposed method of protection against short circuits;

fig. 2 - oscillogram of the "bounce" of the contact when retracted to the interelectrode gap;

fig. 3 - ECHO modes of the part according to the proposed method, taking into account the "bounce" of the contact when retracted to the interelectrode gap.

The method is carried out as follows (Fig. 1).

A sensing voltage is applied to the interelectrode gap through a diode, and an electrolyte is supplied to the chamber. The electrode begins to move before contact with the workpiece, while measuring the voltage part-electrode (U _de ,), which is compared with the input voltage in touch (U _{in cas} ).

Provided that the voltage part-electrode (U _de ) becomes less than the input voltage in touch (U _{in in cas} ), the electrode is removed from the workpiece.

Provided that the voltage of the part-electrode (U _de ) becomes greater than the output voltage from the touch, (U _{in in cas} ), start the delay timer, while the delay time corresponds to the double period of oscillation of the electrode, and start counting the value of the interelectrode gap.

If during retraction to the interelectrode gap, the electrode touches the workpiece, then the process of retracting the electrode is continued, but the delay timer is restarted and the counting of the interelectrode gap starts again from zero. In FIG. 2 shows the oscillogram of the "bounce" of the contact when retracted to the interelectrode gap. The control of the contact of the electrode with the workpiece occurs until the electrode moves back to the specified interelectrode gap, and the delay time is over.

Then the vibration amplitude of the electrode (B) is measured, and if it does not go beyond the specified limits of permissible vibration (B _max <B<B _min ), then processing is started, if the vibration amplitude is out of the specified limits, then an "Accident" signal is issued and processing stop.

An example of the implementation of the method.

The method was implemented in PJSC "UEC-Saturn" on ECHO machines (Fig. 3) with control systems SU-3, SU-4, which made it possible to reduce the number of short circuits and reduce the reject rate by 20%.

The proposed method of protection against short circuits during dimensional electrochemical processing makes it possible to increase the competitiveness of manufactured products.

Claims (1)

A method for protecting against short circuits during electrochemical dimensional processing of a workpiece made of metals and alloys with the creation of synchronous forced oscillations of the electrode, including, before the start of said processing, the approach of the electrode to the workpiece before contact and monitoring the subsequent passage of contacts, characterized in that after contact with the workpiece, the electrode is retracted from the workpiece to a given interelectrode gap and at this time the passage of contacts is monitored, while in the case of contact between the electrode and the workpiece, the delay time starts counting, which corresponds to the double period of electrode oscillations, and the electrode continues to be retracted to a given interelectrode gap, and after the end of the delay time and when the electrode reaches a predetermined interelectrode gap, the electrode vibration amplitude is measured and processing is started, provided that the measured electrode vibration amplitude corresponds to the predetermined limits of permissible vibration.

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