JPS646888B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention uses, as an electrode for electric discharge machining, a rod-shaped electrode whose cross section is circular, triangular, square, etc., instead of a full-shaped electrode. This invention relates to an electrical discharge machining method for performing deep hole or three-dimensional die-sinking.

[Conventional technology and problems to be solved]

When performing complex three-dimensional die-sinking machining using electrical discharge machining using a full-form electrode, an electrode with a shape that corresponds to the desired machining shape is required, and manufacturing this full-form electrode takes time and effort. However, there is a problem in that it is disadvantageous in terms of cost. In this respect, we use an elongated electrode with a constant cross-sectional shape, which is easy to manufacture and inexpensive, rather than a full-form electrode, and the elongated electrode and the workpiece are connected by copy control or program control to
It is advantageous to perform mold engraving of the desired three-dimensional shape by moving the electrodes relative to each other in the Y and Z3 directions, since it does not require much effort or time to manufacture the electrodes. Japanese Patent Publication No. 39-13296 and Japanese Patent Publication No. 13296-1989 suggest that a linear or wire-shaped electrode with a small diameter be used as the elongated electrode.
This is known from Japanese Patent No. 26557, and these publications describe a technique for correcting the length of an electrode in response to electrode wear accompanying electrical discharge machining.

However, although linear or wire-shaped electrodes enable processing of fine shapes, these thin wire-shaped electrodes have low rigidity and are deformed by the flow of processing fluid or discharge voltage. In addition, there is a risk of problems with linearity, especially in those wound on reels, as there may be curls in the winding, making it difficult to accurately perform machining with long feed distances in the depth direction that require long electrodes. It is difficult to do. In this regard, if a rod-shaped electrode with high rigidity is used, the linearity will not be impaired, and deep engraving can be performed with high precision. However, when a round rod electrode with a circular cross section is used as the rod electrode, it is not possible to process corners with a radius smaller than the radius of the round rod electrode or the ridgeline between two adjacent planes. The contour shape that can be obtained is limited. The machining contour shape is limited by the diameter of the electrode in the same way when using linear or wire-shaped electrodes that usually have a circular cross section, but in the case of rod-shaped electrodes, the cross section is triangular. By using a polygon, such as a square or a square, or an electrode in which the corners of these polygons are formed in the shape of an arc with an appropriate radius, it is possible to process corners of arbitrary shapes. However, in the case of rod-shaped electrodes,
As with linear or wire-shaped electrodes, the electrode wears out during electrical discharge machining, so it is necessary to compensate for this electrode wear, but in the case of linear or wire-shaped electrodes, the tip Even if it wears out and becomes rounded, since the diameter is originally small, the change in the tip shape is relatively small, and the effect on machining accuracy is small.However, in the case of rod-shaped electrodes, the diameter is large, so the tip The shape change due to the rounded portion becomes relatively large, and the deterioration of processing accuracy due to this change in electrode shape cannot be ignored. In addition, in the case of polygonal rod-shaped electrodes such as triangles and squares, the wear of the electrode is concentrated at the corners, especially the corners near the tip, so it is difficult to process the electrode by changing its shape. This has a large effect on accuracy. Therefore, when using a rod-shaped electrode, it is not possible to perform accurate machining simply by correcting the length of the electrode to account for electrode wear, as is the case when using linear or wire-shaped electrodes. It is also necessary to consider correction for changes in shape.

From the above viewpoint, the present invention corrects not only the length of the electrode but also the shape of the electrode, especially the shape of the tip, in response to electrode wear accompanying machining in electrical discharge machining using a rod-shaped electrode. The purpose of this is to enable highly accurate machining.

[Means for solving problems]

In order to achieve the above object, the present invention provides movement in the main axis direction of the head of an electrical discharge machine to which an electrode device holding a rod-shaped electrode is attached, and also provides movement in the main axis direction between the rod-shaped electrode and the workpiece. The control device is programmed in advance to perform a movement operation that performs relative movement in orthogonal planes, and a machining operation that generates an electric discharge by applying intermittent voltage pulses between the rod-shaped electrode and the workpiece. In the electric discharge machining method, the electrode device is equipped with a clamp device that enables the positioning and fixing of the rod-shaped electrode by clamping, and the axially drawing out of the rod-shaped electrode by releasing the clamp. , the machining operation is stopped in response to a signal transmitted in relation to the amount of wear of the rod-shaped electrode as machining progresses, the electrode device is moved relative to the rod-shaped electrode length correction reference surface, and the electrode The clamp device of the device releases the clamp on the rod-shaped electrode,
The rod-shaped electrode is extended until the tip touches the electrode length correction reference surface, and then the clamp device is operated to position and fix the rod-shaped electrode to the electrode device, and then the electrode device is moved to the position of the shaping reference electrode. The shape of the tip portion is processed and shaped by moving the reference electrode relatively to the machining electrode and performing rod-shaped electrode electrical discharge machining, and then the electrode device is relatively returned to the machining operation stop position to perform electrical discharge machining. It was configured to resume operation. Moreover, in the second invention,
A head of an electric discharge machine to which an electrode device holding a rod-shaped electrode is attached is moved in the direction of the main axis of the head, and relative movement is caused between the rod-shaped electrode and the workpiece in a plane perpendicular to the direction of the main axis. The moving operation and the machining operation by applying intermittent voltage pulses between the rod-shaped electrode and the workpiece to generate electric discharge are controlled by program control commands preprogrammed in the control device. In the electrical discharge machining method, the electrode device is equipped with a clamp device that enables positioning and fixing of the rod-shaped electrode by clamping and axially drawing out of the rod-shaped electrode by releasing the clamp, and the amount of wear of the rod-shaped electrode as machining progresses. By stopping the machining operation in response to a signal transmitted in relation to the above, moving the electrode device relatively to the position of the shaping reference electrode, and performing electric discharge machining on the rod-shaped electrode using the reference electrode as the machining electrode. The shape of the tip portion is processed and shaped, and then the electrode device is moved relative to the reference plane for rod-shaped electrode length correction, and the clamp device of the electrode device releases the clamp of the rod-shaped electrode, so that the tip of the rod-shaped electrode is extending it until it collides with the electrode length correction reference surface;
Next, the clamp device is operated to position and fix the rod-shaped electrode to the electrode device, and then the electrode device is relatively returned to the machining operation stop position to restart the electric discharge machining operation.

〔Example〕

Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an apparatus for carrying out the method of the present invention, and an electrode device 2, which will be described later with reference to FIG. 2, is attached to a head 1 of an electrical discharge machine. This electrode device 2 clamps and fixes a rod-shaped electrode 5 with a clamp device 3, and this clamp device 3
By releasing this, the rod-shaped electrode 5 is sent out in the longitudinal direction.

FIG. 2 shows details of the electrode device for delivering the rod-shaped electrode 5. As shown in FIG. The electrode device 2 has a hollow cylindrical shape as a whole, and a rod-shaped electrode 5 having an arbitrary cross-sectional shape and size is sent out along this central axis. A clamp device 3 is provided at the tip of the electrode device 2, which is made by dividing a cylindrical body having a conical tapered portion 31A at the end into three or four parts in the radial direction along a plane including the central axis. It consists of a clamp piece 31 having a section, and a hollow cylindrical clamp cylinder 32 having a tightening taper part 32A that engages with the taper part 31A. The rod-shaped electrode 5 passing through the center is clamped and fixed by pressing the clamp pieces 31 having three or four divided parts so as to crowd them radially inward.

Therefore, if the clamp cylinder 32 is pushed upward against the elastic force of the pressing spring 33, the clamped state of the rod-shaped electrode 5 can be released. Part 3
2B is engaged with the tip of the release lever 42 which can be rotated around the pin shaft 42A. Actually, unnecessary friction is avoided by rotatably attaching a roller 43 to the tip of the release lever 42 and engaging the roller 43 with the notch 32B of the clamp cylinder. Of course, the clamping pressure spring 33 can be omitted and the release lever 42 can also be configured to perform the clamping operation. Thus, returning to FIG.
1, the connection end is pushed down, and the release lever 42 is rotated counterclockwise. As a result, the clamp device 3 that fixes the rod-shaped electrode 5 is released.

Next, each process step of the method of this invention will be explained. In FIG. 1A, the workpiece 6 is
It is assumed that the recess 61 is being machined by electrical discharge machining. In general, to the extent that the rod-shaped electrode 5 is not suitable for processing,
Alternatively, the amount of consumption that is consumed to the extent that sufficient machining accuracy cannot be obtained is determined by the various conditions of electrical discharge machining, that is, the degree of discharge energy, the material and size of the rod-shaped electrode, and the material of the workpiece. The amount of wear can be indirectly known from the machining duration time of electric discharge machining or the actual amount of machining on the workpiece. Therefore, in the present invention, data related to the consumption amount of the electric discharge machining electrode is inputted as data to the numerical control system of the electric discharge machine or other appropriate sequence control system, and thereby the rod-shaped electrode 5 in use is When the amount of consumption reaches a predetermined amount, a command is sent to each of the control systems each time the normally set machining time elapses, and the electric discharge machining is temporarily stopped. After stopping the electrical discharge machining, the head 1 is relatively lifted up and away from the workpiece 6, and the head 1 is positioned directly above the electrode length correction reference surface 8, as shown by the broken line in FIG. 1B. It moves it. At that time, the rod-shaped electrode 5 is positioned and stopped by a command from the control system so that the distance from the holding base end of the rod-shaped electrode 5 to the electrode length correction reference surface 8 becomes a predetermined set value l. This is the first step of this invention.

Next, in the second step, fluid pressure is applied to the electromagnetic switching valve 9 in response to commands from each of the control systems to release the clamping device 3 of the electrode device 2, and the rod-shaped electrode 5 is moved simply by gravity or by the head. 1 or inside the electrode device 2 or by a feed-out roller provided above or outside the head, etc., to extend it in the longitudinal direction by Δl (consumed indefinite length) and collide with the reference surface 8 for electrode length correction. Let it happen. In this case, as shown in the figure, the distance l from the holding base end of the rod-shaped electrode 5 to the electrode length correction reference surface 8 is set to a length suitable for the current electric discharge machining, taking into account the electric discharge machining gap. Of course.

The steps up to the second stage above are for correcting the length of the rod-shaped electrode 5, but as mentioned above, in the case of a rod-shaped electrode, especially in the case of a rod-shaped electrode with an irregular shape such as a triangle, the accuracy is In order to perform good machining, it is necessary to correct not only the length but also the shape, so in the third step following the second step, the pressure fluid is removed from the hydraulic cylinder 4 and clamped again. After activating the device 3 and positioning and fixing the rod-shaped electrode 5 to the electrode device 2, the electrode device 2 is moved relatively to the position of the reference electrode 7 for shaping, and the rod-shaped electrode 5 is moved using the reference electrode 7 as a processing electrode. The steps shown in FIG. 1C and FIG. 3 in which the shape of the tip portion is shaped by electric discharge machining are performed. In the process of shaping the rod-shaped electrode 5, as shown in 51A, the tip of the rod-shaped electrode, which has become rounded due to electrical discharge machining, is shaped using a band-shaped reference electrode 7 capable of maintaining a constant standard dimension. As shown in 51B, the tip of the rod-shaped electrode 5 is processed and shaped by electrical discharge machining using the reference electrode 7 as a machining electrode and the rod-shaped electrode 5 as a workpiece. In addition, the above 51 in Figure 3
B shows the shape of the processed and shaped tip portion of the rod-shaped electrode 5, and the electrode 5 is not stretched or drawn out. Therefore, in this third stage process, the electrode is shortened by shaping the electrode for shape correction, but the length of the electrode tip removed by this shaping process is There is no problem if this is taken into account in the distance l set in the first step.

After correcting the length and shape of the rod-shaped electrode 5, the electrode device 2 is relatively returned to the machining operation stop position and the electric discharge machining operation is restarted.

Above, we have explained the case in which the length is corrected in the order of A→B→C and then the shape is corrected in the order of A→B→C in FIG. The length may be corrected after the process has been carried out. In this case, the length of the electrode tip to be removed by the shaping process must be taken into account in the distance l set when correcting the length. Needless to say, there is no such thing.

〔effect〕

According to this invention, since the wear correction of the rod-shaped electrode is automatically performed by numerical control etc., it is possible to perform electric discharge machining with high efficiency, and the wear-out correction of the rod-shaped electrode is not only a length correction but also a shape correction. By also performing electric discharge machining such as deep holes and three-dimensional die carving, it is possible to perform electric discharge machining with high accuracy. Furthermore, according to the present invention, since the wear of the electrodes is properly compensated for, there is no risk of deterioration in accuracy due to wear.
Even with electrodes made of copper or brass, which wear out more easily than copper tungsten or silver tungsten, but are inexpensive, it is possible to perform highly accurate processing, and it also requires less effort and time to manufacture electrodes than with full-form electrodes. This is not necessary and has the effect of reducing the cost related to electrodes in electrical discharge machining. It goes without saying that the present invention is not limited to the embodiments illustrated and described above, and that various changes may be made to each part without departing from the spirit of the present invention as set forth in the claims. For example, not only the electrode device 2, the clamp device 3, and the clamp release means including the release lever 42, but also various other configurations are possible, for example, by omitting the pressing spring 33 as described above,
The clamp release means including the clamp release lever 42 can be configured to perform the clamp operation, and the clamp release means can be configured inside the electrode device 2, or conversely, the electrode device 2 can be used as a reference for electrode length correction. When the distance l is set by relative movement facing the surface 8, the lever 42 is released by an arm, a fluid pressure cylinder, an electromagnetic drive means, etc. fixedly arranged on the installation side of the reference surface 8, or Furthermore, the lever 42 may be configured to be engaged with and operated by a motor-driven forward and backward moving body.

[Brief explanation of the drawing]

Fig. 1 is a simplified side view for explaining each step of this invention, Fig. 2 is a side sectional view of an electrode device used in the method of this invention, and Fig. 3 is a schematic diagram for explaining the process of shaping the tip of an electrode. . 1... Electric discharge machine head, 2... Electrode device, 3
...Clamp device, 4...Fluid pressure cylinder, 5...
... Rod-shaped electrode, 6 ... Workpiece, 7 ... Reference electrode,
8...Reference plane for electrode length correction.

Claims (1)

[Scope of Claims] 1. A head of an electrical discharge machine to which an electrode device holding a rod-shaped electrode is attached is moved in the direction of the main axis of the head, and a space between the rod-shaped electrode and the workpiece is provided in a plane orthogonal to the direction of the main axis. Program control commands preprogrammed in a control device for a movement operation for relative movement of the rod-shaped electrode and a machining operation for generating electric discharge by applying intermittent voltage pulses between the rod-shaped electrode and the workpiece. In the electric discharge machining method, the electrode device is equipped with a clamping device that enables positioning and fixing of the rod-shaped electrode by clamping and letting out the rod-shaped electrode in the axial direction by releasing the clamp, thereby controlling the progress of machining. stopping the processing operation in response to a signal transmitted in relation to the amount of wear of the rod-shaped electrode due to the amount of wear of the rod-shaped electrode, moving the electrode device relatively to a reference surface for correcting the length of the rod-shaped electrode, and adjusting the length of the electrode device. The clamp of the rod-shaped electrode was released by the clamp device, the rod-shaped electrode was extended until the tip collided with the electrode length correction reference surface, and then the clamp device was operated to position and fix the rod-shaped electrode to the electrode device. After that, the electrode device is moved relatively to the position of a reference electrode for shaping, and the shape of the tip portion is processed and shaped by electrical discharge machining of the rod-shaped electrode using the reference electrode as a processing electrode. An electric discharge machining method characterized in that the electric discharge machining operation is restarted by returning the electric discharge machining operation to a position where the machining operation is stopped. 2. Giving the head of the electrical discharge machine, to which the electrode device holding the rod-shaped electrode is attached, movement in the direction of the main axis of the head, and also providing relative movement between the rod-shaped electrode and the workpiece in a plane orthogonal to the direction of the main axis. The moving operation to be performed and the machining operation by applying intermittent voltage pulses between the rod-shaped electrode and the workpiece to generate electric discharge are performed while being controlled by program control commands programmed in advance in a control device. In the electrical discharge machining method, the electrode device is equipped with a clamp device that enables positioning and fixing of the rod-shaped electrode by clamping and axially drawing out of the rod-shaped electrode by releasing the clamp, and Stopping the processing operation in response to a signal transmitted in relation to the amount of consumption of the rod-shaped electrode, moving the electrode device relatively to the position of a reference electrode for shaping, and using the reference electrode as a processing electrode to use the rod-shaped electrode. Processing and shaping the shape of the tip portion by electrical discharge machining, then moving the electrode device relatively onto a reference surface for correcting the length of the rod-shaped electrode, releasing the clamp of the rod-shaped electrode by the clamping device of the electrode device, and Extend the rod-shaped electrode until the tip collides with the electrode length correction reference surface, then operate the clamp device to position and fix the rod-shaped electrode to the electrode device, and then move the electrode device to the machining operation stop position. An electric discharge machining method characterized in that the electric discharge machining operation is restarted by relatively returning to .