JPS597525A - Wire-cut electric discharge machining - Google Patents

Abstract

PURPOSE:To enable to work with a desired angle of inclination by a method wherein a taper machining is performed after the correction of the angle of inclination of a wire electrode is made by the angle of inclination corresponding to the difference between the consumed rod diameters of the wire electrode in the direction of the plate thickness of a workpiece. CONSTITUTION:In wire-cut electric discharge machining, when machining is performed under the condition that the wire electrode 1 is held normal to the workpiece 2, the dimensional error E is generated in the direction of the plate thickness of the workpiece 2. Said error is due to the wear of the wire electrode 1 in the feed direction thereof. The taper machining is performed after the correction of the angle of inclination of the wire electrode 1 is made by the angle theta of inclination corresponding to the dimensional error. In order to machine the workpiece 2 in such a manner that the machined surface is parallel to the direction of its plate thickness, the desired machining is accomplished by performing a taper machining under the condition that the wire electrode is inclined by the angle theta.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a machining method in wire cup electrical discharge machining in which vertical dimensional errors of a workpiece caused by wire electrode wear are corrected by tilting the wire electrode with respect to the workpiece. It is.

Conventionally, in wire-cut electrical discharge machining, when the dimensions of a workpiece are measured after machining, there are often differences in the upper and lower dimensions. Generally known methods for dealing with this problem include changing the distance between the upper and lower guides of the wire electrode, changing the upper and lower machining fluid pressure, or using a second cut method. However, all of these methods have the disadvantage that other sacrifices are large in order to eliminate the vertical dimension difference. In other words, it is known that the method of changing the upper and lower guide spacing is usually contradictory because it is known that the smaller the upper and lower guide spacing, the less wire electrode vibration occurs and the rigidity increases, improving both machining speed and accuracy. It's not a good idea. Furthermore, the method of varying the upper and lower machining fluid pressures is not preferred because it prevents effective ejection of machining chips. Furthermore, the use of the second mill or sotho method naturally requires additional processing time, which is unfavorable from an economical and process perspective.

As above? ! Conventional methods for eliminating vertical dimensional differences in Il workpieces have various drawbacks and often impair other properties.

Therefore, through various experiments, the inventor of the present invention discovered that the above-mentioned vertical dimension difference was caused by wear of the wire electrode, and devised a method for correcting the loss of other characteristics.

First, using Figure @1, we will explain the basis that the difference in the upper and lower dimensions of the workpiece is due to the wear of the wire electrode.

FIG. 1 is a schematic diagram in which the wire electrode (1) is kept perpendicular to the workpiece (2) during processing, which is usually called straight processing. In this case, wire i[(1
) is sent from top to bottom as shown by the arrow in the figure, ←), (b
), the workpiece (2) on the punch side is machined. At that time, the vertical dimension difference E = lLu - L
dl will occur. Also, wire electric [(1)
The range of W indicates the portion consumed by electrical discharge machining. Here, according to the inventor's experiments, when the dimensions of the workpiece (2) were measured from Lu to Ld, that is, at certain intervals from top to bottom, the diameter of the device ear electrode (1) was measured at the same level. The results were almost consistent. That is, this means that the machined surface of the workpiece (2) is equidistant from the consumable surface of the wire electrode (1) and is machined according to its shape.

Therefore, the vertical dimension difference E and the wire electrode diameter difference (the diameter difference in the direction perpendicular to the machined surface before and after processing) almost match.

Next, the characteristics of the vertical dimension difference will be explained with reference to FIGS. 2 and 8.

In Figure 2, (a) represents the vertical dimensional difference E = l Lu - Ld l of the workpiece (2), and (to) Ei is plotted on the vertical axis, and area machining speed FB is plotted on the horizontal axis. It represents the relationship between the two. (9) Fs
As E increases, E increases almost proportionally. It is generally known that as the processing speed increases, the wear of the wire electrode increases, so it should be understood that wear largely dominates the vertical dimensional difference as shown in (b).

Next, FIG. 3 is the same as FIG. 2 regarding the axis, but in this figure, the feeding speed of the wire electrode is indicated by 5iiT5. The results for each feed speed are similar to those in FIG. 2, but what should be noted is the development from WSI to V/Ss. In other words, the figure shows that when compared at the same processing speed, the difference in the upper and lower dimensions of kneading is smaller when the wire electrode feed speed is faster.

Furthermore, since it is a matter of course that the faster the feed speed is, the less the wear is, it can be seen from the figure that the wear largely dominates the difference in the vertical dimension.

As mentioned above, we focused on the fact that the difference in the vertical dimension is largely due to the wear and tear of the wire electrodes, and decided on Kihatsu.

This provides a method that does not impair dimensional accuracy even when processing speed increases, but rather improves it.

FIG. 4 shows the principle of the implementation method according to the present invention.

First, as shown in Figure 1), if the thickness of the workpiece is H, then
Since the vertical dimension difference is E, a tapered surface having an angle θ shown in the figure is formed on the machined surface. In this way, θ is determined in advance by test machining or the like before starting the main machining under the same machining conditions. Next, as shown in (b), in the main processing, the wire electrode (1) is inclined by θ with respect to the vertical direction to perform taper processing.
As shown in the workpiece (2) on the left side of the figure (necessary shape side), it is possible to obtain approximately the vertical dimension difference E=t9.

Furthermore, the taper cutting device used to carry out this processing method is no different from the general ones and is not special.In this way, true straight processing of the workpiece can be performed.

Next, a practical example of the method of the present invention is shown in FIG. In the table shown in FIG. 5, the area machining speed Fs (m) is shown vertically.

The feeding speed WS(n) of the wire tlEm is listed next to it, and the vertical dimension difference E(mn) is all shown. The size relationship is shown below the table. In this way, it can be said that the vertical dimensional difference is controlled by the surface area processing speed and the wire electrode diameter feed speed, regardless of the thickness of the workpiece or processing conditions. This will be explained in more detail. Figure 1, Figure 2, Figure 8
In the figure, it was stated that the difference in the vertical dimension is due to wear and tear on the part of the wire electrode facing the machined surface. The consumption is originally determined by the number of discharges that a unit length of the wire electrode receives per unit time, that is, the current density of 9 per unit length. However, considering that it is said that the area machining speed is approximately proportional to the machining flow, it is no exaggeration to say that in #1, there is a one-to-one relationship between the wear and the area machining speed.

The data obtained for this reason is shown in Figure 5.
Various experiments conducted with different plate thicknesses and processing conditions can be summarized in one table without much difference.In practice, if we have Figure 5, the Taber angle θ during main processing can be calculated using the plate thickness as H. It is expressed like this.

As a result of practical use in Example 1, the vertical dimensions were approximately within several meters. Of course, if you want to perform more precise high-precision machining, it is also possible to perform test machining once under each machining condition and determine the Taber angle based on that.

However, if you want to simplify the process, it is better to use the embodiment shown in FIG.

In other words, before starting the main machining, perform straight line machining (a run-up line is also possible), and wire wire as shown in the figure. (1) Diameter Du,
This method is used in the main processing by measuring each Dd and calculating the Taber angle θ using the formula in the figure.
Indicates the direction facing the machined surface of the I object (2), f is the direction of progress of the process of the wire [fll (1), and 'bFi
This is the part that corresponds to the back in the opposite direction to the direction of machining progress.

DIl, J': Jd is measured in the S direction, and a micrometer or the like is sufficient. Further, Du can be considered to be the same as the diameter of a new wire electrode.

Furthermore, the widths of the machining grooves formed on the upper and lower surfaces of the workpiece (2) may be measured from the same figure, and E' may be determined from the difference.

As mentioned above, various examples of correcting the vertical dimension difference of the workpiece after machining using the Taber angle have been explained and completed. It goes without saying that if the main processing is performed using an angle in which the angular error caused by the above is similarly corrected, a shape with a more accurate desired angle can be obtained. Furthermore, the present invention has the great effect that dimensional accuracy can be maintained at a very high level no matter how much the processing speed is increased, so the effects of its implementation are extremely large.

[Brief explanation of the drawing]

゛Figure 1 is a schematic diagram showing the vertical dimension difference of the workpiece and wire electrode wear, Figures 2 and 8 are graphs showing the characteristics of wire electrode wear, and Figure 4 is a diagram of the principle of the method of the present invention. , FIG. 5 is an embodiment diagram showing a practical data table of the present invention, and FIG. 6 is an embodiment diagram showing a simplified method of the present invention. In the figure, (1) is a wire electrode, (2) is a workpiece, and
. In the drawings, the same reference numerals indicate the same or corresponding parts. Agent Makoto Kuzuno - 4th E = ILLL-L-L I Yang θ・Yu ((Ln(b)

Claims (3)

[Claims] (1) In the minute gap between the feeding wire electrode and the workpiece,
In the machining method of a Tsuya-cut electrical discharge machine equipped with a taber cut device that causes a machining power supply to continuously generate electric discharge using a machining fluid as a medium and inclines the wire electrode at a desired angle with respect to the workpiece, the wire* A wire-cut electrical discharge machining method characterized in that the consumption of W is corrected by an inclination angle of the wire electrode with respect to the workpiece. (2) The scope of claims characterized in that the dimensional error of the workpiece due to wear of the wire electrode is performed based on the tilt angle correction value, which is converted into data in advance, to obtain the desired size and tilt angle. The wire cut electrical discharge machining method according to item 1. (3) Based on the consumption of the wire electrode in the direction perpendicular to the machining progress direction, the difference in the vertical dimensions of the workpiece during previous machining, or the difference in the width of the machining groove between the top and bottom, the inclination angle correction value is requested, and Taber machining is performed based on this. 2. The wire-cut electric discharge machining method according to claim 1, wherein a desired dimension or inclination angle is obtained by performing the following steps.