JPS6052892B2 - Wire cut electrical discharge machining method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wire-cut electrical discharge machining method for accurately electrical discharge machining a workpiece into a desired ring shape using a wire electrode.

In general, in a wire-cut electrical discharge machining apparatus, machining fluid is supplied from a machining fluid supply device 3 in a machining gap formed between a wire electrode 1 and a workpiece 2, usually having a diameter of 0.05 to 0.3 Tmφ, as shown in FIG.

Using the machining fluid 4 as a medium, a machining power source 5 repeatedly generates electrical discharge to machine the workpiece. Further, the movement of the processing part 6 is performed by a drive motor 8 that operates an X-Y cross table 7, and the movement speed in this case is determined by a drive control device 9. processing is performed. Furthermore, on the die surface like press molds, plastic molds, etc.
If a taper is required, a method as shown in FIG. 2 is used.

That is, in order to obtain a predetermined taper angle, a predetermined angle θ is made by the wire guides 11 and 12 from a straight line 10 perpendicular to the workpiece surface 20 onto a plane 21 perpendicular to the processing direction. A predetermined tapered surface is obtained on the die surface by forming and processing the electrode 1 stretched between the wire guides 11 and 12. However, according to the inventor's various research and experiments, in this taper processing method,
Since the taper angle is controlled to be always perpendicular to the direction of machining progress, the guide interval varies depending on the direction of machining progress, the width of the machining groove changes, and machining accuracy decreases.

That is, when machining a taper with an inclination angle θ on the workpiece 2 in FIG. 3c, in the step a of FIG. The electrode 1 vibrates as shown in the figure, and the machining gap is 13 on the upper surface of the workpiece, while the machining gap is 14 on the lower surface, creating a relationship such that machining gap 13<machining gap 14. In addition, in the opposite machining process shown in Fig. 3, the contact points between the wire electrode and the guide are P3 and Po, contrary to step a, and during machining the wire electrode vibrates as shown in the figure, and the upper surface of the workpiece is The gap is 15, and the machining gap is 1 on the bottom surface.
6, and a relationship of machining gap 15>machining gap 16 occurs between the two. Therefore, the machining characteristics are completely different between the steps a and b in FIG. 3, and the width of the machining groove changes, resulting in a decrease in machining accuracy. In order to solve this problem, it is possible to use a point contact guide such as a diamond die as the upper and lower guides. According to this method, although it is true that the guide interval changes very little, the play between the wire electrode and the die inner diameter of the guide causes errors depending on the direction of machining, resulting in a decrease in machining accuracy. That is, as shown in FIG. 4, when the wire electrode 1 is tilted to the right side, there is a gap GL between it and the guide die 22, and when the wire electrode 1 is tilted to the left side, there is a gap GL between it and the guide die 22. A gap GR is generated, and as a result, machining accuracy is reduced. The present invention has been made in view of these points, and it is an object of the present invention to provide a wire-cut electric discharge machining method that can perform machining with good machining accuracy without improving the upper and lower guides of the wire electrode.

This invention will be described in detail below with reference to FIG. In other words, in the conventional wire cut taper processing method,
As shown in the figure, the workpiece 2 is machined at a predetermined angle θ with respect to the reference plane 23 using the upper and lower wire guides 11 and 12. However, due to the above-mentioned essential drawbacks, This causes dimensional errors on the surface (the most important cutting surface in a die). Therefore, in the method of the present invention, in this taper machining step in FIG. 5a, machining is performed so that a machining allowance 17 larger than this dimensional error is left on the die surface at a predetermined machining position 24. After this processing, take out the punch side of the workpiece and set the angle of the wire electrode 1 to the reference plane 23 at a right angle, as shown in Fig. 5b, and follow the same ring movement command as in the taper processing process to a predetermined processing position. Set the wire offset amount 19 to perform machining up to 24 (
In some cases, the offset may be the same as that during taper processing. ) In the machining process again, the high precision machining of the conventional wire cut machining method can be reproduced, and the fundamental drawbacks of the wire cut taper machining method can be eliminated. Also,
The machining allowance after taper machining according to the present invention is actually several μ~
Since the number is +p, the machining conditions can be reduced, and high precision machining with small machined surface roughness can be performed at high speed. This cannot be achieved by performing vertical machining followed by tapered machining. As described above, this invention solves the fundamental drawback of the conventional wire-cut taper machining method, which is the decrease in accuracy, by re-machining after taper machining using the same ring movement command as in the taper machining process, resulting in high-precision machining. Therefore, the workpiece can be precisely machined into a desired ring shape without any improvement in the upper and lower guides of the wire electrode, etc.

Brief description of the drawings Figure 1 is a configuration diagram showing the basic configuration of a wire-cut electric discharge machining device, Figure 2 is a diagram showing a taper machining method, and Figures 3 and 4 are diagrams showing a conventional wire-cut electric discharge machining method. FIG. 5 is a diagram showing an embodiment of the present invention.

In the figure, 1 is a wire electrode, 2 is a workpiece, 11, 1
2 is a wire guide.

Claims (1)

[Claims] 1 The wire electrode and the workpiece are moved relatively, the wire electrode processes the workpiece into a desired contour shape, and the control device controls the relative angle between the wire electrode and the workpiece. In the wire-cut electric discharge machining method that tapers the machined surface of the workpiece, the workpiece is machined into the target shape with a taper leaving a small machining allowance, and then the wire electrode is moved to the reference surface of the workpiece. A wire-cut electric discharge machining method characterized in that the workpiece is returned perpendicular to the machining allowance and the machining allowance portion of the workpiece is re-machined along the contour shape to obtain the target shape.