JPH02311220A - Wire discharge process - Google Patents

Abstract

PURPOSE:To process a work in a desired form at a good precision by determining move positions of a wire electrode by giving passage data for specifying the form of an upper and a lower surface of a work, and distances between the upper surface of a work and an upper guide, between the work upper surface and lower surface, and between the work lower surface and a lower guide. CONSTITUTION:Moving positions S, P for a wire electrode 21 in two planes as wire electrode in/out end surfaces of a work by giving passage data for specifying the form of an upper and a lower surface of the work 22, and distances between the work upper surface and an upper guide, between the work upper surface and the lower surface, and between the work lower surface and a lower guide. A desired work formation is obtained by interpolation at the positions. Processing a formation where taper angles change continuously or processing where the forms of the upper surface and the lower surface of the work are different from each other can thus be achieved easily, and a process precision can be improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a wire electrical discharge machining method for machining a shape in which the Taber angle changes continuously or for machining a workpiece whose top and bottom surfaces have different shapes. It is related to.

[Conventional technology]

Machining in which the Taber angle changes continuously, for example, the circular arcs (machined shape) on the top and bottom surfaces of the workpiece are eccentric as shown in Figure 8, or the rectangular (machined shape) on the top and bottom surfaces of the workpiece as shown in Figure 9. As a wire electrical discharge machining method when the machining shape) is twisted or when the machining shape on the top and bottom surfaces of the workpiece is different:
There was a method described in JP-A-60-56824.

[Problem to be solved by the invention]

In the above conventional technology, interpolation is performed at the wire guy 1' position, and the shape that falls on the top and bottom surfaces of the workpiece is decomposed into minute line segments to approximate circular arcs and straight lines to realize machining. There were problems in that the processing contents (such as Kani program) were complicated and the processing accuracy was low.

The purpose of the present invention is to process shapes with a continuous change in the taper angle or with different shapes on the top and bottom surfaces of a workpiece using simple equipment and processing details (such as a nitrogram). It is an object of the present invention to provide a wire electric discharge machining method that can improve machining accuracy.

[Means to solve the problem]

The above purpose is to provide path data specifying the shapes of the upper and lower surfaces of the workpiece, as well as distances or ratios of distances between the upper guide of the workpiece, the upper and lower surfaces of the workpiece, and the lower surface of the workpiece and the lower guide. This is achieved by calculating the moving position of the wire electrode on two planes, which are the input and output end faces of the wire electrode of the workpiece, and performing interpolation at these positions to obtain the desired machining shape.

[Effect]

In the present invention, the moving position of the wire electrode on two planes that are the input and output end surfaces of the wire electrode of the workpiece is calculated,
Interpolation is performed at this position to obtain the desired machining shape, so this device is simple even when machining shapes where the taper angle changes continuously or when machining when the top and bottom surfaces of the workpiece have different shapes.

Processing can be done depending on the processing content (such as Kani program), and processing accuracy can also be improved.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings. Fig. 1 is a flowchart showing an embodiment of the wire electric discharge machining method according to the present invention, Fig. 2 is a conceptual diagram of workpiece machining according to the method of the present invention, and Fig. 3 shows various parts of Fig. 2 seen from the wire cutter 1 side. It is a figure showing a positional relationship. Here, as shown in FIG. 2, an example will be explained in which the upper surface of the workpiece is processed into a straight line and the lower surface of the workpiece is processed into an arcuate shape.

Due to structural reasons, it is difficult in a wire electric discharge machine to place a workpiece in contact with a guide (not shown) that supports a wire electrode. Therefore, during taper processing, the positions of the upper surface of the workpiece and the upper guide and the positions of the lower surface of the workpiece and the lower guide are different as shown in FIG.

In FIGS. 2 and 3, 21 is a wire electrode, 22 is a workpiece, 22U is the upper surface of the workpiece, 22L is the lower surface of the workpiece, S
is the position of the wire on the upper surface 22U of the workpiece, P is the position of the wire on the lower surface 22L of the workpiece, U is the position of the upper guide, L is the position of the lower guide, and l is the upper surface 22U of the workpiece and the lower surface 2.
2L (workpiece thickness), m is the distance between the workpiece lower surface 22L and the lower guide position, and n is the distance between the workpiece upper surface 22U and the upper guide position U. Here, L and U are P,
It is determined from S, Il, m, and n using the following formula.

L=P+□ (P-3) ...(1)! U=S--1 (P-3)...(2)! In this case, - in (1) is the lower guide position calculation coefficient, (
The minus in 2) is called the upper guide position calculation coefficient.

! As an example of machining, as shown in Fig. 4, the upper surface of the workpiece 22U is
Machining is performed in a straight line from the coordinate value (35, 15) to (55, 60') for the workpiece bottom surface 22L.
,10) to (60,26L38.191), (
A case will be described in which processing is performed in a clockwise circular arc centered at 50°10). Further, in this case, the relationship between the guide position U and the distance (workpiece thickness) l between the upper surface 22U of the L workpiece and the lower surface 22L is shown in FIG. The distance l between the upper surface 22U of the workpiece and the lower surface 22L is 30, the distance m between the lower surface 227 of the workpiece and the lower guide position is 5, and the distance n between the upper surface 22U of the workpiece and the upper guide position U is 10. Note that the unit of each numerical value is mm.

As a processing procedure, first, the I!
, m, n, etc. (Step 1 in Figure 1)
01). After calculating the upper and lower guide position calculation coefficients based on the set values, one block of NC data is read (see steps 102 and 103). After confirming that the read data is not a machining end command (MO2) (see step 104), the relative movement amount of the wire electrode 21 between the workpiece top surface 22U and bottom surface 221 (hereinafter referred to as
(simply referred to as the amount of movement) (Step 10)
(see 5).

In this example, the amount of movement of the work top surface 22U is 55-
35) 2+ (60-15) 2=49.244
...(3)=6-.

In addition, the amount of movement of the lower surface 22L of the workpiece is determined by the radius (5
0-20) 2+(10-10) 2=30...
・(4) Since the central angle is , it becomes .

Next, the workpiece 22 obtained by equations (3) and (6)
Based on the amount of movement of the upper surface 22U and lower surface 22L, the ratio of the moving speeds of these surfaces 22U, 22+ is determined (see step 106). Considering the workpiece lower surface 22L as a reference, when the moving speed of the workpiece lower surface 22L is 1, the moving speed of the workpiece upper surface 22U is 0.855.

Next, using the obtained moving speed ratio, the upper and lower surfaces 22U and 22L of the workpiece are interpolated to obtain the commanded wire positions S and P (see step 107).
Using P and the above upper and lower guide position calculation coefficients, the above (
From equations 1) and (2), the positions U and L (coordinates) of the guide at the start of interpolation (at the start of machining) are determined as follows (see step 108).

Lower guide X coordinate Lx=20+-(20-35)=17
．． 5 Lower guide y-coordinate Ly=10+-(10-15)=
9.167n U Then, movement pulses to the determined positions U and L (coordinates) of the guide are output, and movement, in other words, processing is performed (see steps 109 to 110).

On the workpiece lower surface 22L, if the digital servo's movement amount per position loop sampling time is 5 cylinders,
The position of the bottom surface of the workpiece for the first sampling is (20,
416,14,977). The position of the upper surface 22U of the workpiece is (36,736,18,906) because the amount of movement is l- which is 0.055 times 5.

The guide positions U and L (coordinates) for the first sampling can be found in the same way as at the start. The lower guide position is (1
7,696,14,322), the upper guide position U is (42
, 176, 20, 216).

Hereafter, in the same manner, the second and third sampling...
The guide positions U and L (coordinates) are determined, and a movement pulse to the position is output to perform movement (processing) (see steps 109 to 110 to 103 to 109).

FIG. 6 shows the calculation results in a table, and FIG. 7 shows the calculation results in a graph.

Through the above procedure, the machining shown in FIGS. 4 and 5 is performed, and the machining is finally completed upon receiving the machining end command MO2 (see step 104).

Generally, when the workpiece lower surface 22L is machined in an arc shape,
The trajectory of the wire electrode 21 (machined shape on the lower surface 22L of the workpiece) is Px=Rcos (φ+ωt)...
(8) Py=Rsin (φ+ωt)
−(9).

However, R is the radius, φ is the initial phase, ω is the angular velocity, and t is the time.

Further, when the workpiece top surface 22U is machined in a straight line, the trajectory of the wire electrode 21 there (machining shape on the workpiece top surface 22U) is 5x=I x +Δxt...θ
0) sy=Iy+Δyt...
It is expressed as (11).

However, Ix and Iy are the coordinate values of the starting point, ^χ and Δy are the speed,
t is time.

By substituting equations (8) to (II) into equation (1) above, the locus of the lower guide position (that is, lower guide) can be obtained. That is, from equation (1), LX=PX→□(Px −Sx)! ,',(14-)Rcos (φ+ωt)! ...03) (12) From equations (1, 3), can be found. This has a radius of (1→-)R and a center of! , and the locus of the lower guide becomes an arc shown by this equation.

On the other hand, by substituting equations (8) to (11) into equation (2) above, the locus of the upper guide position (that is, the upper guide) can be obtained.

That is, from equation (2), Ux=Sx+ -(Px-3x)! ...05) Similarly, ...06) can be found from equations (15) and (16). This has a radius of −R and a center of (Iy+△y
t) ) is the equation of the circle, and the locus of the lower guide becomes the arc shown by this equation.

The numerical values in the examples shown in Figures 4 and 5 are: 1 = -30 m-・5 n = -10 I x = 35 y-15 △x = 0.855 *20/49.244 =
0.347Δy =0.855 *45/49.2
44 = 0.781, so convert this to (14)
, Substitute into equation (17).

(Lx+(5,833+0.058t)) 2+
(Ly+(2,510,13t)l 2-352
...09) (U
x-(46,667+0.423t)l 2+ ([1
y-(20+1.041t)) 2-102
...C! 0 is obtained.

In the present invention, the trajectories of the upper guide and the lower guide can be obtained without calculating the above equations (19) and (20).

In the above-mentioned embodiment, the above 1. is applied to the NC device (not shown).
Initialize m and n and based on these settings! , m, n
We have described the case of calculating the ratio (upper and lower guide position calculation coefficients) (see steps 101 to 102 in Figure 1).
, above j2. The ratio of m and n (upper and lower guide position calculation coefficients) may be initially set in the NC device.

[Effects of the Invention] According to the present invention, when the machining shape of the upper and lower surfaces of the workpiece is, for example, a combination of straight lines and circular arcs, the trajectory of the upper and lower guides may become a complicated curve, but this trajectory can be interpolated. Processing can be performed without the need for Therefore, even for workpieces that have conventionally been handled by breaking them down into minute line segments, the present invention allows machining by directly inputting the machining shape of the top and bottom surfaces of the workpiece. Even when machining or machining in which the top and bottom surfaces of a workpiece have different shapes, it is possible to perform the machining using simple equipment and processing details (such as a nitrogram), and the machining accuracy can also be improved.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing an embodiment of the method of the present invention;
Fig. 2 is a conceptual diagram of workpiece machining by the method of the present invention, Fig. 3 is a diagram showing the positional relationship of each part when Fig. 2 is viewed from the wire cutting surface side, and Figs. Figures 8 and 9 are diagrams for explaining specific examples of wire electrical discharge machining.
The figure shows an example of a machined shape in which the Taber angle changes continuously. 21...Wire electrode, 22...Work, 22U...
・Workpiece top surface, 22L...Workpiece bottom surface, S...Wire position on the workpiece top surface, P...Wire position on the workpiece bottom surface, U...Upper guide position, L...Lower guide position.

Claims (1)

[Claims] 1. Passage data for specifying the shape of the upper and lower surfaces of the workpiece in a wire electrical discharge machining method in which the wire electrode is moved relative to the workpiece and electric discharge is generated between the wire electrode and the workpiece to machine the workpiece. At the same time, by giving each distance or the ratio of each distance between the upper guide from the upper surface of the workpiece, between the upper surface and lower surface of the workpiece, and between the lower surface of the workpiece and the lower guide, the movement of the wire electrode in the two planes that are the wire electrode input and output end surfaces of the workpiece is determined. A wire electrical discharge machining method characterized in that a position is determined by calculation and interpolation is performed at this position to obtain a desired machining shape.