JPH04372312A - Tapered shape machining method by wire cut electric discharge machine - Google Patents

Abstract

PURPOSE:To improve the accuracy and quality of a product in the taper- machining of vertically different shape performed by a wire cut electric discharge machine. CONSTITUTION:As in (a), the specified upper shape Cu and lower shape Cd are divided by the same number, and a straight line Li connecting corresponding split points mi, ni is obtained. As in (b), two adjacent planes Hi, Hi+1 including split points m1-j, mi+1 adjacent to the straight line Li and split point mi are determined to obtain parallel planes H'i, H'i+1 existing at the specified wire correcting distance from the planes Hi, Hi+1. An intersection point m'i between the intersecting line (unillustrated) of these planes H'i, H'i+1 and the plane Su to which the upper shape belongs is obtained, and this point m'i is made into a wire center correcting position in relation to the split point mi. In the same way, n'i is obtained in relation to the split point ni of the lower shape Cd, and this point n'i is made into a wire center correcting position in relation to the split point ni. The corrected wire center axis is to be a straight line Li connecting m'i, n'i. Taper-machining is performed by thus correcting the position of the center axis.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of taper machining in which the upper and lower shapes are different (hereinafter referred to as upper and lower irregular shapes) using a wire-cut electric discharge machine.

0002

[Prior Art] When performing taper machining of upper and lower irregular shapes using a wire-cut electric discharge machine, generally the method shown in FIG.
), the upper shape and the lower shape are divided into the same number of division points mi-1 , mi , mi+1 or ni-1 ,
Processing is performed by linear interpolation between ni and ni+1. In this case, it is necessary to correct the wire diameter (the sum of the discharge gap G and the wire radius R), but one method for this correction is to adjust the upper and lower shapes as shown in Figure 2(b). Taking the sum (G+R) of the discharge gap G and wire radius R on the outside, the upper position of the wire center mi-1 ″, mi ″, mi
+1 ″ and lower position ni−1 ″, ni ″, ni+
1''.This method is hereinafter referred to as the approximate estimation method.In addition, as another method, Patent Publication No. 1983-3
As seen in No. 6524, there is a method in which the normal vector at each division point of the upper and lower shapes is determined and the corrected position of the wire is determined based on this. This method is hereinafter referred to as the normal vector method.

0003

[Problems to be Solved by the Invention] Generally, as shown in FIGS. 3(a) and 3(b), the correction amount D for the wire diameter is calculated as D=(G+R)Sec when the taper angle is α. α, and Sec α increases rapidly as α increases. Therefore, in the conventional estimation method, when the taper angle is large, the dimensional error in the product shape becomes large. Further, although the normal vector method takes the taper angle into consideration, there is a problem in that interference (notch) occurs between the wire and the adjacent microplane in the portion where the tapered surface is outwardly concave.

[0004] This invention was devised to solve these problems, and takes into account the taper angle and prevents interference between the wire and the adjacent microplane even in areas where the tapered surface is concave outward. The purpose is to provide a processing method.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention calculates the wire diameter correction position and performs processing as follows.

[0006] a. A straight line L that divides the predetermined upper shape and lower shape into the same number of parts and connects the corresponding division points mi and ni
Find i.

b. Straight line Li and dividing point mi of the upper shape
Two adjacent planes Hi containing each of −1 and mi+1
, Hi+1.

c. Respective parallel planes Hi′, H at predetermined wire correction distances from planes Hi and Hi+1
Find i+1'.

[0009]d. The intersection point mi' between the line of intersection of the planes Hi' and Hi+1' and the plane to which the upper shape belongs is determined, and this point is set as the corrected position of the center of the wire with respect to the division point mi of the upper shape.

[0010] e. Similarly, dividing point ni of the lower shape
ni' corresponding to is determined, and this point is set as the corrected position of the center of the wire with respect to the division point ni of the lower shape.

[0011] Here, the predetermined wire correction distance is the sum of the discharge gap and the radius of the wire.

0012

[Operation] Since taper processing is performed in this way, the center position of the wire is corrected according to the taper angle of each dividing point, and the wire center is parallel to the adjacent microplanes of the upper and lower shapes. Therefore, even if there is a recess in the upper or lower shape, no cut will occur.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the parallel plane method of the present invention will be explained based on the drawings. In Fig. 1(a), Su, S
d and Sr represent the upper surface, lower surface, and tapered surface (line-woven surface) of the workpiece, respectively, and Cu and Cd represent the upper and lower shape curves, respectively.

a. First, as shown in FIG. 1(a), the upper shape Cu and the lower shape Cd are divided into the same number of parts, and the three adjacent points are defined as mi-1, mi, mi+1 and ni-1, ni, ni+1, respectively. mi and ni
Find a straight line Li connecting the .

b. As shown in Fig. 1(b), the upper shape Cu
A plane Hi containing the dividing point mi-1 and the straight line Li is determined, and a plane Hi+1 containing the dividing point mi+1 and the straight line Li is determined.
Establish.

c. From these planes, planes Hi',
Find Hi+1'.

d. Intersection line of planes Hi ′, Hi+1 ′ (
(not shown) is determined, and the intersection point mi' between this intersection line and the upper surface Su of the workpiece is determined, and this point is set as the corrected position of the center of the wire with respect to the dividing point mi of the upper shape Cu.

e. Similarly, a plane Ki including the dividing point ni-1 of the lower shape Cd and the straight line Li is determined, and a plane Ki+1 including the dividing point ni+1 and the straight line Li is determined.

f. From these planes, planes Ki',
Find Ki+1'.

g. The intersection line of planes Ki ′ and Ki+1 ′ (
(not shown) is determined, and the intersection point ni' between this intersection line and the lower surface Sd of the workpiece is determined, and this point is determined as the corrected position of the center of the wire with respect to the dividing point ni of the lower shape Cd.

The center axis of the corrected wire becomes a straight line Li' connecting mi' and ni'.

[0022]

[Effects of the Invention] As understood from the above explanation, the present invention has the configuration described in the claims.
In taper machining of upper and lower irregular shapes using wire electrical discharge machining, even when the taper angle is large, the precision of the product shape is high.
Further, even if there is a recess in the processing path, it is possible to provide a product without wire cuts or the like.

[Brief explanation of the drawing]

FIG. 1(a) is an explanatory diagram of the upper side shape, lower side shape, tapered surface, etc. of the product. (b) is an explanatory diagram of the corrected position of the wire with respect to the division points of the upper and lower shapes.

FIG. 2 is an explanatory diagram of a conventional method for correcting the center of a wire.
Figure a) is an explanatory diagram of a product with a vertically irregular shape, and diagram (b) is an explanatory diagram of the corrected position of the center of the wire with respect to the dividing point of the upper and lower shapes.

FIG. 3 is an explanatory diagram of the amount of correction of the center of the wire during taper processing, where (a) shows when the taper angle is small, and (b) shows when the taper angle is large.

[Explanation of symbols]

Cu Upper shape Cd Lower shape Sr Tapered surface (line woven surface) mi Upper shape division point ni Dividing point of lower shape

Claims (1)

[Claims] 1. A method for machining a tapered shape in a wire-cut electrical discharge machine, which comprises performing wire electrical discharge machining by correcting the center position of the wire as follows. a. The predetermined upper shape and lower shape are divided into the same number of parts, and a straight line Li connecting the corresponding division points mi and ni is determined. b. Straight line Li and dividing points mi-1, mi of the upper shape
Two adjacent planes Hi, Hi+1 containing each of +1
Establish. c. Parallel planes Hi' and Hi+1' located at predetermined wire correction distances from the planes Hi and Hi+1 are determined. d. The intersection point mi' between the line of intersection of the planes Hi' and Hi+1' and the plane to which the upper shape belongs is determined, and this point is set as the corrected position of the center of the wire with respect to the division point mi of the upper shape. e. Similarly, the straight line Li and the dividing point ni-1 of the lower shape
, ni+1, respectively, adjacent two planes Ki and Ki
Define +1. f. Parallel planes Ki' and Ki+1' located at predetermined wire correction distances from the planes Ki and Ki+1 are determined, respectively. g. The intersection point ni' between the line of intersection of the planes Ki' and Ki+1' and the plane to which the lower shape belongs is determined, and this point is set as the corrected position of the center of the wire with respect to the dividing point ni of the lower shape.