JPH01140921A - Method for wire reconnection - Google Patents

Abstract

PURPOSE:To let a wire electrode positively returned to the point of disconnection after the disconnection has been repaired by boring a wire connecting hole on both the program surface and the opposite surface of a work by means of electric discharge machining every after specified numbers of blocks are processed. CONSTITUTION:When electric discharge machining is processed by means of a wire electrode 6 while a work 1 fixed on a table 2 by clamping means 3 and 4 is being moved in accordance with a program, holes F1 through F4 for wire electrode connection are bored on a program surface 5 and a surface on the opposite side not by clipping but by chipping only by means of electric discharge machining every after one or required numbers of blocks B1 through B5 are processed. And then, when disconnection is produced, for example, at a point A, the table 2 is restored back to the position of the hole F4 so as to let the disconnection be repaired for letting the table be returned to the point A of the disconnection while letting the hole F4 be set as a starting hole. Thus, distance and time required for the work to be returned is shortened so as to let the effect of deformation due to internal stresses and of working chips in grooves having been worked before be lessened, thereby enabling the wire electrode to be positively returned back to the point of the disconnection.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to wire electrical discharge machining, and more particularly to a method for reconnecting a wire electrode when it is disconnected during wire electrical discharge machining.

In conventional wire electric discharge machining, machining is started from the machining start hole, and when the wire electrode is disconnected during machining, for example, as shown in FIG.
Processing is performed in block B1 up to 1, and from position P1 to position 11
Machining is performed in block B2 until P2, block B3 from position P2 to position tlP3, block B4 from position P3 to position P4, and when a wire electrode disconnection occurs at position PEA in the middle of processing block B5, the workpiece (workpiece) 101, pass the wire electrode through the machining start hole 100 again, reconnect the wire, and connect the already machined paths P1 to P2. P3
．． A method is used in which the wire passes through P4, returns to the disconnection point A, and restarts machining from the point A.

Problems to be Solved by the Invention However, when the workpiece is deformed due to strain due to internal stress of the workpiece, for example, as shown in FIG. Even if you try to reconnect the wire and return it to the disconnection point A, the already machined groove becomes narrower, and the wire electrode may get stuck in the machined groove at points Q1 or Q2, for example, and the wire electrode may be cut. be.

In addition, as shown in Figure 12 (c), the machining time is long;
When rust occurs in a pre-processed groove, or when wire scraps adhere to a pre-processed groove, the wire electrode may not be able to pass therethrough, and the wire electrode may become disconnected.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a wire reconnector that can reconnect the wire electrode and return it to the disconnection point even if the workpiece is deformed due to internal stress or rust has formed in the already machined groove when making a new wire electrode line. The purpose is to provide a wiring method.

Means and Actions for Solving Problems Each time the machining of one or a desired number of blocks of the program is completed, that is, between the machining of one or the desired number of blocks and the machining of the next block, the program surface of the workpiece and On the opposite side, a hole for wire connection is machined not by cutting but only by scraping by electric discharge, and when repairing a wire breakage, use the hole as a starting hole, reconnect the wire electrode, and return it from the hole to the point of breakage, Start machining from the disconnection point. In this way, the wire electrode is reconnected at the start position of the ivy machining where the wire breakage occurred, so after the wire electrode breakage, the section where the wire electrode is returned to the breakage point is at most one or a desired number of blocks of already machined grooves. Therefore, even if the workpiece is deformed due to internal stress, there is less chance of the wire electrode getting stuck in the already machined groove when it returns to its disconnected state. Also, it will only pass through the already machined groove of the block that was being machined when the wire broke.
Since no long time has passed since machining during this passage, there is no rust or the like occurring in this section, and the wire electrode can be reliably returned to the disconnection point.

Embodiment FIG. 1 is an explanatory diagram for explaining one embodiment, in which a workpiece 1 is fixed to a table 2 by a clamping means 3.4, and the wire electrical discharge machine changes the program plane every time one block of a cutting program is machined. A hole F approximately twice the diameter of the wire electrode is machined on the work surface opposite to the hole F. 1st
In the example shown in the figure, block B1 is machined, and hole F1 is machined between blocks B1 and B2.

Similarly, hole F2 is machined between the end of machining of block B2 and the start of machining of block B3, and hole F3. Hole F4 is machined between block B4 and block B5. In this way, the hole F is machined on the work surface opposite to the program surface 5 between the end of machining of one block and the start of the next block. If the wire electrode breaks during processing, for example, at point A in Figure 1, the wire electrode is pulled out and the hole F1 is machined at the processing start position of the block where the wire breakage occurred. That is, in this case, the wire electrode is passed through the hole F4, connected, and returned to the disconnection point, and processing is restarted from the disconnection point A. In this way, even if a wire breakage occurs, the hole F machined at the machining start position of the block where the wire breakage occurred
is used as a hole for wire connection, and after connecting the wire electrode, return it to the disconnection point, and the return section is only between the blocks, so as shown in Figure 1, the workpiece is deformed by the internal stress of the workpiece, and the existing Even if the machining groove becomes narrower, there is little effect on the machining groove of the last block being machined.
It is easy to return the wire electrode connected to the disconnection point A. In addition, even if there is rust or wire scraps attached to the pre-processed groove, the wire electrode will only be passed through the block where the disconnection has occurred, so it will not be affected by this.
The wire electrode can be moved to the breaking point.

In order to machine the hole F at the end of the cutting block, it is possible to program a hole drilling NC command at the end of the processing movement block of the cutting program, or by using the control device of the wire electric discharge machine. Hole machining may be set using a CRT/MDI or the like connected to a certain numerical control device. For example, when programming a hole machining command in a machine program, create a code that commands hole machining, such as an M code, and issue the following command along with the program's machining movement block command.6GOIX
Y M ...... (1) When such a block is commanded, or when CRT/MDI
When hole machining is set, the numerical control device of the wire electric discharge machine performs machining of the hole F every time each machining movement block is completed, as described above.

Figures 2 to 8 show examples of machining the above-mentioned hole F, and in order to prevent the workpiece 1 from being cut off into a columnar shape, the workpiece is scraped off by electric discharge machining, which blows away minute metals from the workpiece by electric discharge. The hole is machined using a chisel (hereinafter, this process is referred to as fill hole machining).

Figures 2 and 3 show an arc on an arc whose radius is equal to the offset value and touches the center path of the wire electrode that moves away from the programmed path by the set offset value r at the corner between the blocks. The center path of the wire electrode passes through this, and FIG.
FIG. 3 shows an example of machining the program surface 5 having a concave shape.

Fig. 2 shows an example in which the machining surfaces of the first block and the second block are convex, that is, the program surface 5 is convex. The center of the wire electrode 6 is separated by the set offset value r from the program path commanded by L1. L2, and the route L1. A hole F is formed on the surface opposite to the programming surface 5 so that the center path of the wire electrode 6 passes on a circular arc whose radius in contact with L2 is equal to the offset value r.

In this case, since the radius of the arc is equal to the offset value r, the center of the arc is not cut off into a cylindrical shape by electric discharge, and the hole F is formed by filling the hole. Since the wire electrode 6 draws a circle with a radius of the offset value r, the diameter of the machined hole F is approximately four times the offset value r, that is, approximately twice the diameter of the wire electrode 6. In addition, when forming an even larger hole F, after completing the circular arc machining with the radius r described above, both paths L1. It may be processed so that the center of the wire electrode 6 passes over a circular arc that is in contact with L2.

FIG. 3 is an explanation of the machining of the hole F when the programming surface 5 is a concave portion.
The central path L1. The wire electrode 6 is programmed and machined on the surface opposite to the programming surface so that the center of the wire electrode 6 passes over a circular arc that is in contact with L2 and has a radius of offset value r.

FIG. 4 and FIG. This shows an example of machining a hole F using an arc whose center is on the bisector of the corner formed by the second block and whose radius has an offset value r as the center path of the wire electrode 6. 1st. The central path L1 of the wire electrode 6 of the second block. FIG. 5 shows an example in which a hole F is machined between blocks in which the program surface 5 is convex by a circular arc path that passes through the intersection point of L2 and is centered on the half line of the corner surface. The wire electrode 6 passes through a point moved by the offset value r in the opposite direction to the offset direction of each block from the intersection of L2, and has its center on the bisector of the corner angle and has a radius of the offset value r. This is an example of machining the center path and machining the hole F.

Figures 6 and 7 show an example of machining a hole F by moving the wire electrode 6 linearly, and Figure 8 shows an example of machining a hole F between a block for linear machining and a block for circular arc machining. The hole F may be machined using any route for the wire electrode, but it is important to select the route so that the hole is filled and that the diameter of the hole F is smaller than the diameter of the wire electrode 6.
It is necessary to process the wire so that it is approximately twice the diameter of the wire electrode 6 or more so that it can be passed through the wire.

As described above, the pattern of holes F to be machined between blocks is determined, and each block is machined by a hole machining command such as an M code during a program, or by a hole machining command using a CRT/MDI, etc. Let hole F be machined.

Note that the hole drilling ever-turn differs depending on whether the machining shape formed by the two blocks is a convex or a concave part, but when commanded by a program, a command code such as an M code is used to command whether to drill a convex or concave hole. You may also do so. Also,
The numerical control device that controls the wire electric discharge machine may determine whether the block is a convex portion or a concave portion based on the two block paths.

The determination of whether this is a convex portion or a concave portion is made based on the offset vector and whether or not the program plane 5 is offset to the left or to the right in the direction of travel. As shown in FIG. 9, when machining is performed so that the program surface 5 is convex, if the advancing direction of the wire electrode 6 is the direction of the solid line (A), the offset is a left offset, and the offset vector of the first block Cross product of 101 and the second offset vector 100
l 2 becomes negative. Also, if the wire electrode advances in the direction of the broken line (b), the offset is a right offset,
Offset vector e1. Since e2 is switched, W411 X e 2 becomes positive.

Similarly, when machining a recess as shown in Figure 10,
If the wire electrode moves in the direction of the solid line (a), it will be offset to the right and the first. The offset vector of the second block is the cross product of 100, 100, x 100.

is negative, and if the wire electrode advances from the direction of the broken line (0), the outer product 100 x 100 with left offset is positive.

When these are arranged, it becomes as follows.

Outer product e xi,, positive, left offset...Concave outer product 100 x 100, positive, right offset...Convex outer product 100, x
102 negative, left offset...f outside the convex part! 4 W I
X M 2 negative, right offset...Concavity As described above, whether the program surface 5 is a protrusion or a concave can be determined by the cross product of the offset vector 100× and whether the offset is left or right. Whether the offset is to the left or right is determined by the offset setting, and the offset vectors M and M2 are determined by the movement command for the book in question.

Assuming that the movement command for the first block is (x, yl) (in order to simplify the explanation, consider the movement as an incremental amount), the offset vector 100 is the movement Since the direction is perpendicular to the command (x, yl) and the magnitude thereof is the offset value r, the X-axis and Y-axis components of the offset vector 100 are respectively equal to each other. In other words, the offset vector 100 is...
... (2) Similarly, the offset vector of the second block is 102
is... (3).

If we calculate the cross product 100 x 102 from equations (2) and (3), we get: Depending on whether this value is positive or negative and whether the offset is on the right or left side of the path, the program surface 5 will be a convex or concave part. If it is a convex part, machine the hole F using the pattern set on the surface opposite to the program surface 5 of the workpiece, as shown in Figures 2, 4, 6, and 8. conduct. Further, if it is determined that it is a recess, the hole F is machined using one set pattern as shown in FIGS. 3, 5, and 7.

Effects of the Invention According to the present invention, each time the processing of one or a desired number of blocks in the program is completed, a hole for wire connection is machined and the next block is machined. The wire electrode was passed through the hole drilled at the machining start position of the block, the wire electrode was reconnected, the wire electrode was returned to the disconnection point, and machining was started from the disconnection point. The only section to be returned to the point is the already machined groove of the block where the wire breakage occurred, making reworking the wire breakage quick and easy. Even if the workpiece is deformed due to internal stress, the effect of this internal stress on the already machined groove of the block where the wire breakage has occurred is small, so that the wire electrode can be easily returned to the point of wire breakage. In addition, since the wire electrode returns to the already machined groove of only the block where the wire breakage occurred, it is unlikely that rust has formed in the machined groove because not much time has passed since the electric discharge machining in this returning section. Also, since there is less wire debris attached, the wire electrode can be easily returned to the disconnection point.
Unlike the conventional method, it is possible to reduce the possibility that the wire electrode will be disconnected again while the wire electrode is being returned to the disconnection point due to deformation of the workpiece, rust, etc.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an embodiment of the present invention, Figs. 2 to 8 are explanatory diagrams of holes to be machined between blocks, Figs. 9 and 10 are explanatory diagrams of offset vectors, and Figs. Figure 11 is an explanatory diagram of offset vector calculation, Figure 12 (a) ~
(c) is an explanatory diagram of workpiece deformation and rust generation in conventional wire electric discharge machining. DESCRIPTION OF SYMBOLS 1... Workpiece, 2... Table, 3.4... Clamp means, 5... Program surface, 6... Wire electrode, F... Hole, Ll, L2... Wire electrode center route,
r...offset value, hundred, hundred,...offset value ctor. 1st mouth 4th mouth 50 8th mouth 11th mouth 12th mouth

Claims (2)

[Claims] (1) In wire electrical discharge machining, each time machining of one or a desired number of blocks of a program is completed, a hole for wire connection is machined on the opposite surface of the workpiece to the program surface by only cutting by electrical discharge, A wire reconnection method characterized in that when repairing a wire breakage, the above-mentioned hole is used as a start hole and the wire electrode is reconnected. (2) The wire reconnection method according to claim 1, wherein the wire connection hole is approximately twice the diameter of the wire electrode used.