JPS6347018A - Method and device for diesinking electric discharge processing - Google Patents

Abstract

PURPOSE:To make quick processing of a precision hole by installing an electrode and a work to be processed on two tables rotating at the equal speed synchronously round horizontal axes in parallel to each other, and by performing the electric discharge processing. CONSTITUTION:A electrode 21 and a work to be processed 22 are installed on No.1 and No.2 rotary tables 17, 19, respectively, in such an arrangement that their axes are parallel to the X axis with each other. Then the end face of the electrode 21 is precisely faced the hole processing position of the work 22, and if the electrode 21 and the work 22 are out of alignment, their axes shall be put in alignment through control by motors 12, 16. Then the tables 17, 19 are revolved at the same speed by synchronous motors 18, 20. Then a processing liquid trough 3 is moved in the X direction by a main shaft motor 7, and the electrode 21 and the work 22 are approached to perform electric discharge processing, to accomplish quick processing of precision hole, wherein abnormal discharge etc. is well prevented.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a die-sinking electric discharge machining method and apparatus for machining a hole having a shape corresponding to the cross-sectional shape of an electrode. The present invention relates to a horizontal die-sinking electrical discharge machining method and apparatus for forming horizontal holes in a workpiece.

(Prior Art) Die-sinking electrical discharge machining is often performed when it is required to form a hole with an extremely small diameter or a hole with a precise cross section in a workpiece. Die-sinker electrical discharge machining uses an electrode with a cross-sectional shape that corresponds to the shape of the required hole, and moves the electrode toward the workpiece while generating electrical discharge between it and the workpiece in an insulating machining fluid. By doing so, the surface of the workpiece is removed minute by minute.

When such die-sinking electric discharge machining is performed, conventionally, the workpiece is placed below the T-water bath, and the electrode is vertically lowered from above. Therefore, the workpiece has
Holes were machined from the top surface gradually downward.

However, such a machining method has a problem in that machining debris with a high specific gravity tends to settle and accumulate at the bottom of the machining hole. Furthermore, since bubbles generated by the discharge rise from the machined hole, clean flow of the machining fluid into the discharge portion is obstructed. Moreover, in the center of the bottom of the machined hole,
There is a dead point in the liquid flow. Therefore, decomposition products of the machining fluid due to electric discharge tend to stay in the machining hole. If machining debris and decomposition products stay in the discharge gap in this way, a differential discharge or a short circuit between electrodes will occur, resulting in a decrease in machining accuracy or inability to perform machining.

Conventionally, countermeasures against this problem include providing a jet hole in the electrode to force the machining fluid to flow between the electrodes, or creating a pumping effect by raising and lowering the electrode or by self-flushing motion. Efforts were made to eliminate the dispersion of processing waste and decomposition products.

[Problems to be Solved by the Invention] However, in the case where the electrode is provided with a jet hole, it is desirable that the jet hole has a small flow resistance in order to generate a forced jet of machining fluid. If the diameter is increased, unprocessed parts will be left. Therefore, it is difficult to obtain an effective forced jet.

Furthermore, in the case where the pumping action is performed by an electrode, the control becomes complicated and the machining speed decreases.

The present inventors have found that such problems can be almost eliminated by arranging the electrodes horizontally and machining the holes horizontally. If the hole is machined horizontally, the -H of the air bubbles will cause an upward flow of the machining fluid.
Clean machining fluid always flows into the machining hole from below. Moreover, dead points of the liquid flow do not occur at the bottom of the hole where machining debris is generated. Therefore, retention of decomposition products is prevented. Also,
Since there is no need to push the sinking machining debris upwards as in the case of machining a hole vertically, it can be easily discharged.

By the way, when drilling holes in the horizontal direction like this, the processing fluid flows from the bottom to the top, so the processing fluid that exists at the bottom of the hole becomes clean, and the processing fluid that exists at the top of the hole becomes clean. The processing fluid tends to contain a relatively large amount of decomposition products. Therefore, there is a problem in that the accuracy of the machined holes differs between the upper and lower parts.

The present invention was made in view of these problems, and its purpose is to constantly supply clean machining fluid to the discharge gap and to easily discharge machining debris and decomposition products generated by the discharge. The objective is to ensure that the holes are machined with uniform accuracy all around the circumference.

(Means for solving the problem) In order to achieve this object, in the present invention, the electrode is arranged horizontally so that the hole in the workpiece is machined in the horizontal direction, and during the process, the electrode is arranged horizontally. The machine and workpiece are rotated around the horizontal axis in synchronization.

The electrode and the workpiece are mounted on first and second rotary tables, respectively, which rotate about mutually parallel horizontal axes. The rotary tables are rotated at the same speed by synchronous motors. Also,
The rotary tables are configured to be relatively movable horizontally by a main axis and relatively movable in a vertical plane by a numerically controlled drive.

(Function) By machining the hole horizontally in this way, the machining fluid can wave from the bottom to one side as described above, and clean machining fluid is always supplied to the discharge gap. Become so. Further, machining waste and decomposition products generated by electric discharge can be easily discharged. By synchronously rotating the electrode and the workpiece around the horizontal axis, the hole rotates during machining, so that the entire circumference is machined under the same conditions.

Further, by making it possible to relatively move the first and second rotary tables to which the electrode and the workpiece are attached in a vertical plane by numerical control,
For example, it is possible to make the electrode draw an arbitrary circular orbit.

Therefore, even at a position eccentric from the rotation axis of the workpiece,
It becomes possible to machine a predetermined hole.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

In the drawings, FIG. 1 is a longitudinal sectional side view showing an embodiment of a die-sinker electric discharge machining apparatus according to the present invention, and FIG. 2 is a sectional front view thereof.

As is clear from these figures, a machining liquid tank 3 is placed on the base 2'' of this electrical discharge machining apparatus 1. This machining liquid tank 3 is supported by a horizontal guide rail 4 formed on the upper surface of the base 2 so as to be slidable in the X-axis direction, that is, in the left-right direction in FIG. X on base 2
A main shaft 5 parallel to the shaft is rotatably supported, and a ball nut 6 integrally provided on the lower surface of the machining liquid tank 3 is engaged with a screw of the main shaft 5. The main shaft 5 is rotationally driven by a main shaft motor 7 installed on the base 2. In this way, processing liquid tank 3
is horizontally moved in the X-axis direction.

A gate-shaped frame 8 is integrally provided on one side of the base 2. The upper part of this frame 8 is a horizontal guide rail 9. And, by the guide rail 9,
A guide post 10 is supported so as to be slidable in the Y-axis direction, that is, in the left-right direction in FIG. A feed screw shaft 11 parallel to the Y-axis is rotatably supported on the frame 8, and the guide post 10 is adapted to mesh with the feed screw shaft 11. Further, the feed screw shaft 11 is rotationally driven by a reversible motor 12 that is operated according to a command signal from a computer (not shown). In this way, the guide post 10.

Its position in the Y-axis direction is numerically controlled.

The guide post 10 is provided with a guide portion 13 in the X-axis direction, that is, in the vertical direction. The guide portion 13 allows the tool support stand 14 to be slidably guided in the X-axis direction. Further, the tool support base 14 is moved in the X-axis direction by a feed screw shaft 15 rotatably supported by the guide post 10, and its position in the X-axis direction is determined by a reversible motor 16 that drives the feed screw shaft 15.
It is now controlled by. The motor 16
They are also operated according to command signals from a computer.

A first rotary table 17 is rotatably supported on the tool support base 14 . The rotational axis of the first rotary table 17 is parallel to the X-axis. The first rotary table l7 is rotatably driven by a synchronous motor 18 provided within the tool support stand 14. The synchronous motor 18 is operated at a predetermined speed by the computer.

In this way, the first rotary table 17 can be moved arbitrarily within a plane perpendicular to the X-axis, that is, within a plane perpendicular to its rotational axis, and can also be rotated at a predetermined speed around its rotational axis. has been done. In this embodiment, the numerically controlled drive device that moves the first rotary table 17 in a plane perpendicular to its rotation axis includes a feed screw shaft 11 in the Y-axis direction, a drive motor 12 thereof, and a feed screw shaft in the Z-axis direction. 15, its drive motor 16, and these motors 12,
16.

On the other hand, a second rotary table 19 is provided in the machining liquid tank 3 at a position opposite to the first rotary table 17 .

This second rotary table 19 is supported by the machining liquid tank 3 so as to be rotatable around a rotation axis parallel to the X-axis. The second rotary table 19 is rotatably driven by a synchronous motor 20 provided within one side wall of the machining liquid tank 3. The rotation speed of this synchronous motor 20 is controlled by a computer so that the second rotary table 19 is rotated at the same speed as the first rotary table 17.

The first rotary table 17 and the second rotary table 19 are both made of a good electrical conductor, and are located between the first rotary table 17 and the tool support stand 14 and between the second rotary table 19 and the machining liquid tank 3. are electrically isolated from each other. These first and second rotary tables 17
．． 19 are respectively connected to both poles of a power supply device (not shown).

An electrode 21, which is a tool, is attached to the first rotary table 17 on its axis of rotation. This electrode 21 is shaped like a shaft and has a cross-sectional shape corresponding to the hole to be machined, and is removably mounted on the first rotary table 17 with its center axis parallel to the X-axis. It has become. On the other hand, a workpiece 22 on which a hole is to be machined is removably attached to the second rotary table 19.

The machining liquid tank 3 is filled with a machining liquid 23 such as oil having insulating properties.

The workpiece 2 is machined using the electrical discharge machining apparatus 1 configured as described above.
2, first attach the electrode 21 with the cross-sectional shape corresponding to the hole to the first rotary table 17 so that its center axis is parallel to the X-axis. It is attached to the second rotary table 19 so that the direction of the hole is parallel to the X-axis. At this time, it is desirable that the center axis of the electrode 21 coincides with the rotation axis of the first rotary table 17, but it may be slightly eccentric.

Further, the workpiece 22 may be attached at an appropriate position.

At this time, the position of the central axis of the electrode 21 and the hole drilling position of the workpiece 22 are measured by an appropriate measuring device 3 and input into the computer.

Next, the motors 12 and 16 are controlled to move the first rotary table 17 in a plane perpendicular to the X axis, that is, in the YZ plane, so that the end surface of the electrode 21 accurately faces the hole drilling position of the workpiece 22. Then, by the synchronous motors 18 and 20,
The first rotary table 17 and the second rotary table 19 are rotated at the same speed. This rotation is said to be performed at a low speed of about one rotation every 30 seconds, for example.

At this time, if the hole machining position of the workpiece 22 is eccentric from the rotation axis of the second rotary table 19, the hole machining position will draw a circular orbit centered on the rotation axis.

Therefore, the first rotary table 17 is moved within the YZ plane by controlling the motors 12 and 16 by the computer.
The electrode 21 is caused to draw the same circular orbit as the hole machining position of the workpiece 22. Even when the electrode 21 is eccentric from the rotational axis of the first rotary table 17, this can be similarly compensated for by controlling the motors 12 and 16.

In this way, the hole machining positions of the electrode 21 and the workpiece 22 are held relatively constant with their central axes coinciding with each other. Furthermore, the electrode 21 and the hole machining position of the workpiece 22 rotate at the same speed around the horizontal central axis. That is, the rotational axis of the first rotary table 17 and the rotational axis of the second rotary table 19 are aligned, the electrode 21 and the hole machining position are arranged on the rotational axis, and they are rotated at the same speed. The same thing will happen.

Therefore, in this state, the spindle motor 7 is operated to move the machining liquid tank 3 in the X-axis direction, thereby bringing the electrode 21 and the workpiece 22 closer together. Then, a power supply device causes electric discharge to occur between the electrode 21 and the workpiece 22. Then, the workpiece 22
A hole 24 having a shape corresponding to the cross-sectional shape of the electrode 21 is formed in the hole 24 .

At this time, the hole 24 will be machined in the horizontal direction, as shown in FIG. Therefore, the discharge gap 25 between the end surface 21a of the electrode 21 and the bottom surface 24a of the machined hole 24 extends in the vertical direction. As a result, the bubbles generated in the discharge gap 25 due to the discharge rise as indicated by the arrows in FIG. 3, resulting in an upward flow of the machining fluid 23 in the discharge gap 25. . In this way, clean machining fluid 23 comes to flow into the discharge gap 25 from below, and machining fluid 23 containing decomposition products and the like comes to be discharged upward. Moreover, since the upward flow occurs over the entire surface of the discharge gap 25, a dead point of the liquid wave does not occur in the discharge gap 25. Therefore, the discharge gap 25 is always filled with clean machining fluid 23.

In addition, machining debris with a large specific gravity generated by the machining is deposited at the bottom of the hole 24, but since the hole 24 is opened in either direction, the machining debris etc. are absorbed by its own weight, the self-flushing movement of the electrode 21, or the like. Easily discharged by horizontal hunting etc. In this case, it is not necessary to actively horizontally vibrate the electrode 21 in order to discharge the processing waste, and the naturally occurring horizontal movement of the electrode 21 is sufficient.

During the machining, the electrode 21 and the machining hole 24 are rotated around a horizontal axis. Therefore, the machined hole 24 is turned upside down, and the machining conditions are made uniform over the entire circumference. Moreover, since the electrode 21 and the machined hole 24 are rotated synchronously, the cross-sectional shape of the hole 24 is maintained accurately.

During machining, if the level of the machining fluid 23 in the machining fluid tank 3 decreases, the machining fluid 23 in the machining hole 24
is also discharged at the same time. Therefore, the flammable machining fluid 23 does not remain in the discharge gap 25, and the machining fluid 23 is prevented from catching fire due to overripe.

FIGS. 4 and 5 are vertical and side-to-side cross-sectional front views showing different embodiments of the die-sinking electric discharge machining apparatus according to the present invention. In this embodiment, the same reference numerals are given to the parts corresponding to the embodiment shown in FIGS. 1.2.

In this embodiment, a cross feed table 3o is placed on the base 2 of the electrical discharge machining apparatus l, and a machining fluid tank 3 is placed on this cross feed table 30. The transverse feed table 3o is slidably supported by a horizontal guide rail 4 formed on the upper surface of the base 2, and is horizontally moved in the X-axis direction by a main shaft 5 rotationally driven by a main shaft motor 7. It has become. Further, the machining liquid tank 3 is slidably supported by a guide rail 31 in the Y-axis direction formed on the upper surface of the horizontal feed table 3o, and is rotated in the Y-axis direction by a feed screw shaft 11 rotationally driven by a reversible motor 12. It is designed to be moved horizontally. In this way, processing liquid tank 3
is adapted to be moved horizontally in the XY plane with respect to the base 2.

A vertical guide post 32 is integrally provided on one side of the base 2. A tool support stand 33 is supported by this guide post 32 so as to be slidable in the Z-axis direction. This tool support stand 33 is moved in the Z-axis direction by a feed screw shaft 15 provided on the guide post 32, and its position is controlled by a reversible motor 16 that rotationally drives the feed screw shaft 15. .

The tool support stand 33 has its tip inserted into the machining liquid tank 3, and the first rotary table 17 is attached to the tip. The first rotary table 17 is rotatably supported around a rotation axis parallel to the X-axis, and is rotationally driven by a synchronous motor 18 provided within the tool support 33.

On the other hand, a second rotary table 19 is provided in the machining liquid tank 3 at a position opposite to the first rotary table 17 .

This second rotary table 19 is also rotatably supported around a rotation axis parallel to the X-axis, and is rotationally driven by a synchronous motor 20.

These first and second rotary tables 17.19 have electrodes 2
1 and a workpiece 22 are respectively mounted and electrically connected to both poles of the power supply.

In the electric discharge machining apparatus f configured in this way, the motor 12 controls the relative position of the first rotary table 17 with respect to the second rotary table 19 in the Y-axis direction, and the motor 16 controls the second rotation of the first rotary table 17. The relative position in the Z-axis direction with respect to the table 19 is controlled. That is, the first rotary table 17 is moved relative to the second rotary table 19 within the YZ plane orthogonal to its rotation axis. Therefore, similar to the embodiment shown in FIG. 1.2, the relative positional relationship between the electrode 21 and the workpiece 22 can be maintained constant. The electrode 21 and the workpiece 22 are rotated at the same speed around a horizontal axis of rotation. As a result, the machined hole 24 is turned upside down during processing.

``Also in this embodiment, the machined hole 24 is machined in the horizontal direction. Therefore, the same effect as explained in FIG. 3 can be obtained.

In the above embodiments, the second rotary table 19 is moved in the X-axis direction by the main shaft 5, but the first rotary table 17 is moved in the X-axis direction by the main shaft 5.
It can also be moved in the axial direction. Further, the second rotary table 19 can also be moved in the Z-axis direction.

(Effects of the Invention) As is clear from the above description, according to the present invention, the electrodes are arranged horizontally and the holes are machined in the horizontal direction, so that the upward flow generated by the bubbles causes discharge. Clean machining fluid is constantly supplied to the gap, and decomposition products, machining debris, etc. can be easily discharged. Furthermore, since the electrode and workpiece are rotated around the horizontal axis during machining, the machined hole is turned upside down, and the entire circumference of the hole is machined under the same conditions.

Therefore, the occurrence of abnormal electrical discharge, etc. is prevented, and the hole can be precisely and quickly machined.

and a first
Since the second rotary table is relatively moved within the vertical plane by numerical control, even if the rotation axes of the electrode and the machined hole are different, they can be moved relatively to the same horizontal rotation axis. It can be rotated around. Furthermore, since the rotation speed may be low, a normal numerically controlled machining device can be used as is.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view showing an embodiment of a die-sinker electric discharge machining apparatus according to the present invention; FIG. 2 is a cross-sectional front view of the electric discharge machining apparatus as seen from line II-II in FIG. 1; Figure 3 is for explaining the operation of the electrical discharge machining device.
FIG. 4 is a longitudinal sectional side view showing another embodiment of the die-sinker electrical discharge machining apparatus according to the present invention, and FIG. 5 is an enlarged sectional view of the electrical discharge machining part, and FIG. FIG. 2 is a cross-sectional front view of the electrical discharge machining device. 1... Die-sinker electrical discharge machining device 3... Machining liquid tank 5.
・・Main shaft 7 ・・Main shaft motor 11 ・
...Feed screw shaft 12...Motor (numerically controlled drive device) 15...Feed screw shaft 16...Motor (numerically controlled drive device) I7...ff
11 Rotary table 18...Synchronous motor 19...
Second rotary table 20...Synchronous motor 21...
Electrode 22... Workpiece 23... Machining fluid 24 Machining hole 25... Discharge gap

Claims (2)

[Claims] (1) An electrode having a predetermined cross-sectional shape is placed in a machining liquid tank so that its center axis is horizontal, and a workpiece is placed so that its machining position faces the end surface of the electrode. , by rotating these electrodes and the workpiece synchronously around a horizontal axis, causing an electric discharge to occur between the electrode and the workpiece, and moving the electrode horizontally relative to the workpiece. A die-sinking electric discharge machining method, wherein a hole having a shape corresponding to the cross-sectional shape of the electrode is machined in the workpiece. (2) a first rotary table that is rotatably supported around a horizontal axis of rotation in a machining liquid tank, and on which an electrode having a predetermined cross-sectional shape is attached parallel to the axis of rotation; a second rotary table provided in the machining liquid tank opposite to the rotary table and capable of rotatably supporting a workpiece around a rotation axis parallel to the rotation axis of the first rotary table; a synchronous motor that rotates a second rotary table at the same speed around each rotation axis; and a synchronous motor that horizontally moves the first rotary table in a direction parallel to the rotation axis relative to the second rotary table. a main shaft that can rotate the main shaft; a main shaft motor that rotationally drives the main shaft; and a numerically controlled drive device that can move the first rotary table relative to the second rotary table in a plane orthogonal to the rotation axis. A die-sinking electric discharge machining apparatus comprising: and a power supply device capable of causing electric discharge between the electrodes attached to the first and second rotary tables and the workpiece.