JPS60255322A - Holding device for rod-shaped electrode in electric discharge machining device - Google Patents

Abstract

PURPOSE:To improve processing characteristics by mounting an electrode holding and delivering mechanism on an electrode holder via a collet mounting pipe, guiding the lower end of the electrode to permit the collet mounting pipe to be pushed down independently of electrode servo feed. CONSTITUTION:An electrode 1 is held between a collet holder 12 and a tapered bush 13 via a spring 22, the tip of the electrode 1 is guided by a guide bush 19, and thereby a hole made in a workpiece 3 is subjected to electric discharge machining by upper and lower servos of a main shaft 6. With a touch sensitive plate 25 being brought into contact with the workpiece 3, the main shaft 6 is elevated by a prescribed amount, and thereby air is supplied to a piston 24 to push down a collet mounting pipe 16. Thus, an electrode holding and delivering mechanism 11 is operated to lower the electrode 1 by a prescribed distance to pull up the piston 24 and to clamp the electrode 1 by means of a collet holder 12 for again subjecting the workpiece to electric discharge machining. With such arrangement, the captioned device can be miniaturized, with electrode deflection being restricted and processing characteristics being improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement of a rod-shaped electrode holding device in an electric discharge machining apparatus.

[Prior art]

Conventionally, electric discharge machining equipment has been used as a method for efficiently machining small holes, but the electrode holding device part is
It was as shown in the figure. In the figure, 1 is a pipe electrode for a small hole, 2 is a collet holder that holds and fixes the pipe electrode 1, 3 is a workpiece, 4 is an electrode mounting surface plate to which the collet holder 2 is attached, and 5 is a power supply device for machining. . 6
is a main shaft for servo feeding the pipe electrode 1 up and down, and is driven in the up and down direction by a servo drive motor (not shown). 7 is a head for guiding and attaching the main shaft 6. Further, 8 is a machining fluid supplied to the pipe electrode 1, which passes through the electrode mounting surface plate 4 and the pipe electrodeposition 1 to the electrical discharge machining area 3.
Processing powder generated in the processing area 3' is efficiently removed and processing performance is improved.

A guide bush 9 guides the pipe electrode 1, and is provided to reduce the deflection of the electrode in the electrical discharge machining area 3' as much as possible and improve machining performance. Reference numeral 10 denotes a holding arm for holding and fixing the guide bush 9, which is attached and fixed to the head 7.

The operation of the conventional device as described above is as follows. The pipe electrode 1 is servo-fed by the main shaft 6 in the direction of the arrow in the figure according to the machining process, thereby drilling a hole in the workpiece 3. In this case, the electrode length l between the guide bush 9 and the collet holder 2 needs to be set to a length that takes into account the processed plate thickness and electrode wear. Further, the guide bush 9 and the collet holder 2 are arranged in the same straight line with respect to the servo feeding direction, so that no bending force is applied to the electrodes. The holding arm 10 has a structure that can be adjusted in the vertical direction according to the thickness of the workpiece 3 so that the position of the guide bush 9 can be fixed as close to the workpiece surface as possible.

Since the conventional device is constructed as described above, it is necessary to set a distance of the electrode length l between the collet holder and the guide bushing, which requires a correspondingly large distance from the processing surface. This method requires a holding arm to which a guide bush for guiding the electrode is required, and has disadvantages such as a complicated and large mechanism, and a restriction on the mounting space for the workpiece, resulting in poor operability. Furthermore, if the pipe electrode is thin, the electrode in the section having the electrode length l tends to swing, which causes electrode swing in the processing area 3', resulting in a reduction in processing performance. [Summary of the Invention] The present invention eliminates the drawbacks of the above-mentioned conventional electrode holding device, makes the device compact without using the conventional holding arm, minimizes electrode deflection, and improves operability. It is an object of the present invention to provide a rod-shaped electrode holding device in an electrical discharge machining device that makes it possible to obtain high machinability.

The rod-shaped electrode holding device in the electric discharge machining apparatus of the present invention has an electrode gripping and feeding mechanism that is equipped with a collet holder that clamps the electrode at the lower end of the collet mounting pipe, which has an electrode storage space inside with an upper end closed and a lower end opened. The collet mounting pipe to which the electrode gripping and feeding mechanism is connected is housed in an electrode holder, a guide bushing for guiding the electrode is attached to the lower end of the electrode holder, and the upper part of the electrode holder is attached to an electrode mounting surface plate. and by pressing down the upper end of the collet mounting pipe with an air-driven piston provided inside the electrode mounting surface plate,
It is characterized by feeding and supplying the pure and processed feed portions of the electrode independently of the servo feed of the electrode. The details will be explained below with reference to embodiment figures.

[Embodiments of the invention]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of a rod-shaped electrode holding device in an electric discharge machining apparatus according to the present invention. In the figure, 1 is a rod-shaped (or pipe-shaped) electrode, 3 is a workpiece, 3' is its electrical discharge machining area, 5 is a machining power supply, 6 is a servo feed spindle, 7 is a head for guiding and attaching the spindle 6, 8 indicates machining fluid.

12 is a collet holder for clamping the electrode, 16 is a taper bushing that guides a part of the collet taper of the collet holder 12, 14 is a spring attached to the lower part of the taper bushing 13, and 15 is a rubber bushing, which grips and draws out the electrode. It constitutes a mechanism 11.

Reference numeral 16 denotes a collet mounting pipe whose upper end is closed and whose lower end is open, and which has an electrode storage space inside to store a rod-shaped electrode. They are screwed together, and an introduction hole 17 for the machining fluid 8 is provided on the side near the upper end of the pipe. The collet mounting pipe 16 is housed in an electrode holder 18 with the electrode gripping and feeding mechanism connected thereto, and the electrode holder 18 has a guide bushing 19 for guiding the electrode 1 attached to its lower end, and an electrode mounting surface plate 20 attached to its upper part.
is combined with The guide bushing 1'9 is made of a highly wear-resistant insulating material such as ceramic or sapphire. 21 is a lock screw for fixing the electrode holder 18 to the electrode mounting surface plate 20, and 22 is a lock screw for fixing the electrode holder 18 to the electrode mounting surface plate 20;
) is a spring that supports the electrode in a vertically movable manner and applies a force to clamp the electrode.

Inside the electrode mounting surface plate 20, a collet and a piston 24 driven by air 26 for pressing the upper end of the mounting pipe 16 and pushing it down are provided. Controlled OFF.

25 is attached to the lower end of the guide bush 19;
This is a contact sensing plate for sensing contact between the workpiece 3 and the electrode housing portion, and is supported by a spring 26 so as to be movable up and down, and is connected to a contact sensing device 27, thereby electrically detecting contact.

Next, the operation and effect of the rod-shaped electrode holding device as described above will be explained. The electrode 1 is clamped by a spring 22 between a collet holder 12 and a tapered bush 16, and the tip of the electrode is guided by a guide bush 19. However, in this state, the electrode performs drilling by electrical discharge between the electrode and the workpiece 3 by the vertical servo of the spindle B. When trying to improve machining performance, a pipe-shaped electrode is used as the electrode, and the machining fluid enters from the machining fluid introduction hole and is supplied from the upper end of the pipe through the electrode (pipe) to the machining area 3'. .

When the machining progresses and the spindle moves downward a distance, the contact sensing plate 25 comes into contact with the upper surface of the workpiece 3 and senses the contact. When such a situation occurs, move the main shaft 6 upward by a certain amount, then drive the piston 24 with air to push down the collet mounting pipe 16, and operate the electrode gripping and feeding mechanism to hold the electrode at a certain level. Feed the amount downward. (This feeding mechanism is generally similar to that used in mechanical pencils, etc.) With the electrode fed out a fixed amount held by the taper bush 16, spring 14, and rubber bush 15,
The air solenoid valve is turned OFF, air is removed from the piston 24, the piston 24 is raised, and the electrode is clamped with the collet holder 12. In this way, the electrode is fed out and machining is started again in the clamped state, and the above operations are repeated until the desired machining is completed. The amount of electrode feeding is determined by the piston drive (
It can be adjusted by increasing or decreasing the number of ON-OFF cycles.

In the above embodiment, the electrode holder 18 is fixedly attached to the electrode mounting surface plate 20. However, if the machining condition is to be improved by rotating the electrode, etc. , a rotation mechanism is provided between the electrode mounting surface plate and the electrode holder.

Furthermore, if one electrode is to be replaced automatically, this can be done relatively easily by providing a mechanism for automating the insertion and removal of the electrode holder 18 on the electrode mounting surface plate 20 and automating the lock 21.

〔Effect of the invention〕

According to the rod-shaped electrode holding device of the present invention as described above, since the electrode machining feed and the electrode supply are made independent,
The distance between the electrode clamp part, the electrode guide part, and the workpiece surface can be maintained at a nearly constant distance regardless of whether the distance is short or the machining progress is progressing, which improves the rigidity of the electrode in the machining part, Run-out is extremely small and highly accurate machining can be achieved. In addition, the electrode can be stored inside the electrode holder, resulting in a compact structure with a small distance from the processing surface, and has many excellent features such as ease of operation (and easy support for automatic electrode replacement, etc.). Effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a rod-shaped electrode holding device in the electric discharge machining equipment of the present invention, and FIG. 2 is a longitudinal sectional view of a conventional rod-shaped electrode holding bag lid. 1i electric ffl, 2: collet holder, 3: workpiece, 3
': Electrical discharge machining area, 4: Electrode mounting surface plate, 5: Machining power supply, 6: Spindle, 7: Head, 8: Machining fluid, 9 guide bush, 10: Holding arm, 11: Electrode gripping mechanism, 12: Collet holder, 13: Taper push, 14 Spring, 15: Rubber push, 16: Collet mounting pipe, 17: Machining fluid introduction hole, 18: Pole holder, 19 Ni guide bush, 20: i! Electrode mounting surface plate 21: lock screw, 22 spring, 23 I air, 24: piston, 25: contact sensing plate, 26: spring, 27: contact sensing device. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Patent Attorney Sanro Kimura Figure 1

Claims (4)

[Claims] (1) The upper end is closed, the lower end is open, and there is an electrode storage space inside. An electrode gripping and feeding mechanism equipped with a collet holder for clamping the electrode is coupled to the lower end of the collet mounting pipe, and the electrode gripping and feeding mechanism is connected to the lower end of the collet mounting pipe. The combined collet mounting pipe is stored in an electrode holder, a guide bush for guiding the electrode is attached to the lower end of the electrode holder, the upper part of the electrode holder is connected to an electrode mounting surface plate, and the electrode mounting surface plate is A rod-shaped electrode in an electrical discharge machining apparatus, characterized in that by pushing down the upper end of the collet mounting pipe with an air-driven piston provided inside, the amount of electrode consumption and machining feed is paid out and supplied independently of the servo feed of the electrode. holding device. (2) The electrode gripping and feeding mechanism is characterized by comprising a collet holder, a tapered bushing that guides a tapered part of the collet holder, and a spring and a rubber bushing attached to the lower part of the tapered bushing. A rod-shaped electrode holding device in an electric discharge machining apparatus according to claim 1. (3) A rod-shaped electrode holding device in an electric discharge machining apparatus according to claim 1, wherein the guide bushing is made of an insulating material such as ceramic or sapphire. (4) Electrical discharge machining according to claim 1, characterized in that a contact sensing plate is attached to the lower end of the guide bush, and a contact sensing device detects contact between the electrode housing portion and the workpiece. A rod-shaped electrode holding device in the device.