JPS6034223A - Electric discharge machine - Google Patents

Abstract

PURPOSE:To improve removal of chips and to recover the state of working gap quickly to normal state by stopping application of working pulses for predetermined time upon detection of abnormal discharge and further vibrating the electrode relatively. CONSTITUTION:Abnormal discharge in the working gap (G) between an electrode 8 and a work 9 is detected by a detector 18 for detecting the voltage drop. Upon production of abnormal discharge detection signal S1, application of working pulse from a pulse generator 20 is stopped for predetermined interval set in a timer 22 by means of a switch 21. Furthermore, electrode 8 feeder 5 is controlled by NC controller 23 to widen the gap (G) then the electrode 8 is vibrated to remove chips well.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric discharge machining apparatus, and more particularly to an electric discharge machining apparatus capable of effectively removing machining chips from a machining gap.

Generally, in electrical discharge machining equipment, when abnormal discharge such as arc discharge occurs in the machining gap, a significant increase in chips and the like is observed in the machining gap. In order to remove this condition and perform normal electrical discharge machining again, increase the machining gap length and
It is necessary to maintain cleanliness between the discharge electrodes. For this reason, in conventional electrical discharge machining equipment, when abnormal electrical discharge etc. occurs,
For example, by jumping the electric discharge machining electrode up and down by about 0.5 to IW, chips are urged to be removed and abnormal electric discharge is stopped. However, depending on the above-described operation, chips could not be removed sufficiently, and efficient electrical discharge machining could not be continued.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electrical discharge machining apparatus that can quickly and reliably restore the state of the discharge gap to a normal state when an abnormal discharge such as an arc discharge occurs during electrical discharge machining. It's about doing.

The configuration of the electric discharge machining apparatus of the present invention includes means for supplying machining pulses between the electric discharge machining electrode and the workpiece, and means for performing servo feed control between the electric discharge machining electrode and the workpiece. In the electric discharge machining apparatus, the electric discharge machining apparatus includes: a detection means for detecting a discharge state of an electric discharge machining gap between an electric discharge machining electrode and a workpiece; means for stopping the application of the electric discharge to the electric discharge machining gap for a predetermined period; It is characterized in that it includes a means for imparting vibrational motion to an object.

Before imparting a photographing motion to the electrical discharge machining electrode and/or the workpiece, the machining gap length is widened to a predetermined length, and then the electrical discharge machining electrode and/or the workpiece is moved vertically, horizontally, and horizontally.
Alternatively, it can be moved vertically and horizontally by a predetermined dimension, thereby providing a photographing motion.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows an embodiment of an electrical discharge machining apparatus according to the present invention. The electric discharge machining apparatus 1 includes a base 2 and a column 3 fixed to the base 2, and the column 3 is provided with a machining head 4.

An electrode feed motor 5 is provided at the upper end of the processing head 4, and a feed screw 6, which is driven one rotation (1) by the electrode feed motor 5, is screwed into a spindle 7. The spindle 7 is supported by the processing head 4 so as to be able to move up and down, so that the rotation of the feed screw 6 allows the spindle 7 to move forward and backward in its axial direction.

A machining electrode 8 is fixed to the lower end of the spindle 7, and the electric discharge machining gap length between the machining electrode 8 and the workpiece 9 can be adjusted by the electrode feed motor 5.

A processing table 11 on which a processing tank 12 is placed is provided on the base 2 via an X-Y moving device 10.
In the machining tank 12 filled with the machining fluid A, there is a workpiece 9. is placed.

The X-Y moving device 10 is a device for moving the processing table 11 in two orthogonal directions (X, Y directions) within a plane (X-Y plane) perpendicular to the feeding direction of the electrode 8. The processing table 11 is driven in the X direction by a feed screw 14 connected to an X direction motor 13, and the processing table (4) 11 is driven in the Y direction by a feed screw (not shown) connected to a Y direction motor 15. driven by.

These motors 5, 13.15 are configured such that each motor 5, 13.15 can provide the required relative movement between the machining electrode 8 and the workpiece 9 for machining.
It is connected to a control device 16 including a numerical control device, and is configured to perform electrical discharge machining under so-called three-axis control. Reference numeral 17 indicates a machining pulse power supply device for supplying machining pulses between the machining electrode 8 and the workpiece 9, and the machining pulse power supply device 17 outputs machining pulses. A pulse is applied to the machining gap between the machining electrode 8 and the workpiece 9. Processing electrode 8
In order to detect whether or not an abnormal discharge has occurred between the machining electrode 8 and the workpiece 9, an abnormal discharge detector 18 that responds to the potential difference between the machining electrode 8 and the workpiece 9 is provided. When electrical discharge occurs and the machining gap voltage decreases, abnormal electrical discharge detector 1
The level of the detection output signal S1 outputted from 8 becomes high level. The detection output signal S is supplied to the control device 16 and the processing pulse power supply device 17.
When the level of I is low, that is, when normal electric discharge machining is being performed, machining pulses are applied from the machining pulse power supply device 17 to the electric discharge machining gap, and the machining pulse is applied from the control device 16. Each motor 5, 13 .
A signal for driving 15 is output. In addition, for processing 1
The voltage in the machining gap between the pole 8 and the workpiece 9 is also applied to the control device 16 as a feedback signal for servo control. The relative movement between them is NC-controlled by the control device 16.

On the other hand, when the level of the detection output signal S becomes high, that is, when it is detected that some abnormal discharge state has occurred, in response to the rise in the level of the detection output signal S, The machining pulse power supply bag #17 interrupts the application of the machining pulse voltage to the machining gap for a predetermined period, and the control device 16 can effectively remove chips from the machining gap and perform normal discharge. The motor is set at 5°13.15 so as to give a predetermined vibration motion between the machining electrode 8 and the workpiece 9 instead of the relative motion under NC control.
control.

This vibration operation is performed in all or part of the period during which the application of processing pulses is stopped.

FIG. 2 shows a circuit diagram of the control system of the electrical discharge machining apparatus 1 shown in FIG. The processing pulse power supply device 17 is
Machining pulse generator 2 that outputs the required electrical discharge machining pulses
0, a switch 21 provided between the output terminal of the processing pulse generator 20, the processing electrode 8, and the workpiece 9, and an opening/closing control signal S for controlling opening/closing of the switch 21;
It consists of a timer 22 that outputs .

In response to the change in the level of the detection output signal S from the rLJ level to the rHJ level, the timer 22 sets the level of the opening/closing control signal S2, which is its output signal, to the rHJ level for a predetermined time T, thereby causing the normally closed state to change. The switch 21 is kept open for a time T.

When the level of the detection output signal SI of the timer 22 is at the rLJ level, the level of its output signal, the opening/closing side (l) control signal S, remains at the rLJ level, and therefore the switch 21 is in the closed state. It becomes. As a result, when normal electrical discharge machining is being performed in the electrical discharge machining gap G, the switch 21 is in a closed state and a machining pulse is applied to the machining gap G via the switch 21. When abnormal discharge occurs and is detected by the abnormal discharge detector 18, the timer 22 is activated.
The switch 21 is opened for a predetermined time T, and the machining pulse is prevented from being applied to the electric discharge machining gap G.

As mentioned above, when abnormal discharge occurs in the machining gap G, the application of the machining pulse to the machining gap G is stopped, and at the same time, a relative distance is created between the workpiece and the machining electrode for chip removal. For the purpose of giving a vibration, the detection output signal S1
is applied to a control device 16 comprising a numerical (NC) control device 23 and a CPU 24. In the CPU 24 in the control device 16, when the detection output signal SI is at the "L" level, a command is provided to apply the required relative movement between the workpiece 9 and the processing electrode 8 in order to perform the desired processing. (8) The motors 5, 13.15 are driven, but the detection output signal S1
A program is stored for controlling the NC control device 23 so that a movement for chip removal can be applied between the workpiece 9 and the processing electrode 8 when the workpiece reaches the rHJ level. A movement is applied between the workpiece 9 and the processing electrode 8 for chip removal.

This program moves the electrode feed motor 5 so that the machining electrode 8 is separated from the workpiece 9 and the machining gap is greater than or equal to a predetermined length.
In order to apply vibrational motion between the processing electrode 8 and the workpiece 9, the electrode feeding motor 5 moves the processing electrode 8 up and down, and the motors 13 and 15 move the processing electrode 8 up and down. This step consists of a step of controlling the table 11 to swing in the horizontal direction. Therefore, when this program is executed, the machining electrode 8 is first raised by a predetermined amount along the axial direction of the spindle 7, and then the machining electrode 8 performs a so-called jumping motion and moves toward the workpiece 9. performs an oscillating motion in the X-Y plane, thereby making it possible to apply an oscillating motion between the machining electrode 8 and the workpiece 9 for chip removal.

Note that this vibration movement is time-limited by a timer (not shown) provided in the NC control device so that it is performed for a period equal to or shorter than the timer time T determined by the timer 22. configured to give.

According to such a configuration, when the machining electrode 8 is pulled up, the abnormal electrical discharge is first stopped, and then the machining gap and tip in the enlarged state are effectively eliminated by the vibration movement, so that the machining gap and the tip in the enlarged state are effectively eliminated. When abnormal discharge such as arc discharge occurs, the state of the discharge machining gap can be quickly and reliably returned to the normal state.

When the above-mentioned vibration movement ends, the level of the signal S outputted from the timer 22 becomes the rHJ level again, the switch 21 is closed, and a machining pulse is applied to the machining gap G. At this time, the numerical control device 23 in the control device 16 returns to the original NC machining control state, so that when the desired electrical discharge machining is restarted (11) 17... Pulse power supply device for machining.

It becomes.

According to the present invention, as described above, it is configured to be able to detect the occurrence of abnormal discharge such as arc discharge that occurs in the machining gap, and when the occurrence of abnormal discharge is detected, the workpiece The application of machining pulses between the machining electrode and the machining electrode is stopped, and relative vibration motion is applied between the workpiece and the machining electrode, thereby reliably stopping abnormal electrical discharge and eliminating chips in the machining gap. Since this can be quickly and reliably eliminated, if an abnormal discharge such as an arc discharge occurs during machining, the state of the discharge machining gap can be quickly and reliably returned to the normal discharge machining state.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an electric discharge machining apparatus according to the present invention, and FIG. 2 is a circuit diagram showing a control system of the apparatus shown in FIG. 1...-Electro discharge machining device, 5... Electrode feeding motor, 8...
...Processing electrode, 9...Workpiece, 10-...X-Y
Moving device, 11... Processing table, 13.15...
Motor, 16...control device, (12) Patent applicant Sodick Co., Ltd. Agent Patent attorney Masatoshi Takano

Claims (1)

[Claims] 1. A device comprising means for supplying a processing pulse between a processing electrode and a workpiece, and means for controlling servo feed between the processing electrode and the workpiece. In the electric discharge machining apparatus, the electric discharge machining apparatus includes: a detection means for detecting a discharge state in an electric discharge machining gap between the machining electrode and the workpiece; a first means for stopping the application of pulses to the electrical discharge machining gap for a predetermined period; An electric discharge machining apparatus comprising: second means for applying relative vibration motion between the two. 2. In an electric discharge machining apparatus, comprising means for supplying a machining pulse between a machining electrode and a workpiece, and a means for performing servo feed control between the machining electrode and the workpiece. , a detection means for detecting a discharge state in the discharge machining gap between the machining electrode and the workpiece, and a detection means for detecting the machining pulse in response to the detection of abnormal discharge. a first means for stopping the electric discharge to the machining gap for a predetermined period; a second means for increasing the length of the electric discharge machining gap to a predetermined length in response to abnormal discharge being detected by the detection means; An electrical discharge machining apparatus comprising: a third means for applying a relative vibration motion between the machining electrode and the workpiece during a period during which application of the machining pulse by the first means is stopped.