JPH079263A - Wire cut electric discharge machine - Google Patents

Abstract

PURPOSE:To eliminate interference of a tool in the neighborhood of an internal corner or a concave surface even in case the width of a minute curved surface is made smaller than the radius of a wire by determining the shortages of the tool diameter correcting amount within X-Y plane on the basis of the tapers of two planes. CONSTITUTION:The shortages DELTAr1 and DELTAr2 of the tool diameter correcting amount (r) within the X-Y plane on the basis of the tapers of the plane H1 and plane H2 are determined from formulae DELTAr1=r/sin(theta1)-r and DELTAr2=r/sin(theta2)-r. In the attached figure, L1 represents the straight line tying the dividing point Pm-1 to Pm while L2 does the straight line tying the dividing point Pm to Pm+1, and also L1' represents the straight line generated by parallel movement of straight line L1 for a distance corresponding to the shortage DELTAr1 of the tool diameter correcting amount within the plane Hu while L2' does the straight line produced by parallel movement of straight line L2 for a distance corresponding to the shortage DELTAr2 of the tool diameter correcting amount within the plane Hu. The intersection Pu of the two straight lines L1' and L2' is determined, and this is used as the wire correcting position of the dividing point Pu. Therein theta1 represents the angle formed by the plane H1, on which the dividing points Pm, Pm+1, Pn lie, relative to the X-Y plane, while theta2 does the angle formed by the plane H2, on which the dividing points Pm, Pm-1, Pn lie, relative to the X-Y plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a taper machining method for a product having a so-called vertically different shape in which the upper shape and the lower shape of the product are different by a wire cut electric discharge machine.

[0002]

2. Description of the Related Art Conventionally, in the taper machining of products having different top and bottom shapes by a wire cut electric discharge machine, the correction position of the wire is calculated by the following method.

A Product shape is considered as an assembly of minute curved surfaces.

B The normal vector of each minute curved surface is calculated.

C Correct the tool radius correction amount from each minute curved surface in the direction of the normal vector.

Further, in taper machining of products having different top and bottom shapes, as shown in FIG. 5, since the wire inclination θ changes step by step during the processing, it is necessary to change the tool diameter correction amount R step by step. Tool radius compensation function (G41,
G42) could not be used. For this reason, the NC program for machining a product having a vertically different shape has been programmed by previously determining the diameter of the wire to be used, calculating the tool diameter correction amount when using the wire.

[0007]

In tapering a product having a vertically different shape, it is necessary to reduce the width W of the minute curved surface in order to improve the processing accuracy of the product.
If the width W of this minute curved surface is made smaller than the radius r of the wire, so-called tool interference (cutting) occurs near the inner corner in the case of a product shape having an inner corner as shown in FIG. 4, for example. For this reason, conventionally, the width W of the minute curved surface cannot be reduced so much that accurate processing cannot be performed.

In addition, as described above, in tapering a product having different top and bottom shapes, if it is desired to change the diameter of the wire to be used and use the NC program before the change, a large processing error will occur. The NC program corresponding to the diameter was recreated.

The present invention was made in view of such a problem, and the first invention is so-called near the concave surface or the inner corner even if the width W of the minute curved surface is smaller than the radius r of the wire. The second aspect of the present invention provides a highly accurate machining method in which tool interference (cutting) is unlikely to occur, and the second invention is a simple and sufficient precision even when machining with a wire having a diameter different from the wire diameter assumed when creating the NC program. The purpose is to provide a simple processing method.

[0010]

In order to achieve the above object, a method of machining a taper shape by a wire-cut electric discharge machine according to the first aspect of the present invention corrects the center position of the wire as follows. To do.

1 The upper shape is F _u , the plane parallel to the XY plane to which the upper shape F _u belongs is H _u , and the lower shape is F _d ,
Let H _d be a plane parallel to the XY plane to which the lower shape F _d belongs.

(2) Shapes F _u ′ and F _d ′ obtained by correcting the upper shape F _u and the lower shape F _d by the tool radius correction amount r in the respective planes H _u and H _{d to} which they belong.

3 Shapes F _u ′ and F _d ′ are equally divided.

4 P _m is an arbitrary division point of the shape F _u ′, P _{m + 1} and P _m−1 are adjacent division points, and the corresponding shape F
The division points of _d' are P _n , and the adjacent division points are P _{n + 1} and P _n-1 .

[0015] 5 dividing point P _m, the P _m-1, P _n belongs plane and H _1, the plane H ₁ to the XY plane and the angle between theta _1.

[0016] 6 dividing point P _m, the P _{m +} 1, P _n belongs plane and H _2, the plane H ₂ is the XY plane and the angle and theta _2.

7 Insufficiency Δr ₁ and Δr of the tool radius correction amount in the XY plane based on the taper of the plane H ₁ and the plane H _2.
2 is calculated from the following equations (3) and (4).

Δr ₁ = r / sin (θ ₁ ) −r (3) Δr ₂ = r / sin (θ ₂ ) −r (4) 8 division points P _m-1 And the straight line connecting P _m and L ₁ , the dividing point P _m
And P _{m + 1} the straight line connecting the L _2, a straight line translated by shortage [Delta] r ₁ of the tool diameter compensation amount a straight line L ₁ in the plane H _u L ₁ ', similarly planar linear L ₂ H _u Let L ₂ ′ be a straight line that is translated by the shortage Δr ₂ of the tool radius correction amount.

9 An intersection point P _u between the straight line L ₁ ′ and the straight line L ₂ ′ is obtained and set as a wire correction position of the division point P _m .

10 The following processing similar to 5 to 9 is performed at the division point P.
_This is performed for _n to obtain the wire correction position P _d of the division point P _n .

A straight line connecting 11 P _u and P _d is the central axis of the wire.

Next, the taper machining method of different shapes in the vertical direction when changing the wire diameter of the second invention is to change the program of the Δr portion of the tool diameter correction amount R = r / sin θ = r + Δr before the change. This is used as it is for the subsequent correction of the Δr portion of the wire, and the correction of the changed r portion of the wire is performed by the tool radius correction function (G41, G42) of the NC device. Where θ is the wire tilt angle.

[0023]

In the first aspect of the invention, when the wire position is corrected, the similar upper and lower shapes drawn outside the upper and lower shapes of the product and separated by the radius of the wire to be used are corrected by equally dividing them. Even if the division width is smaller than the radius of the wire, so-called tool interference (cutting) is unlikely to occur in the concave surface of the product or in the vicinity of the inner corner.

In the second aspect of the invention, the angle of inclination of the taper wire which is currently used in the wire-cut electric discharge machine is in the range of 70 ° to 90 °. However, the error is extremely small.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the first invention will be described with reference to FIGS. 1 (a) and 1 (b).

1 The upper shape of the product is F _u , and the upper shape F _u
Let H _u be a plane parallel to the XY plane to which is belonged, F _{d be} the lower shape of the product, and H _d be the plane parallel to the XY plane to which the lower shape F _d belongs.

2 Upper shape F _u and lower shape F _{d of the} product
A plane H _u each belongs, in the H _d, the tool diameter compensation amount r
Then, the similar shapes F _u ′ and F _d ′ that have been corrected only are obtained.

3 The similar shapes F _u ′ and F _d ′ are equally divided.

4 Let P _{m be} an arbitrary division point of the similar shape F _u ′, P _{m + 1} and P _m−1 be adjacent division points, and the corresponding division points of the similar shape F _d ′ be P _n , the adjacent division point is P
_{Let n + 1} and P _n-1 .

[0030] 5 dividing point P _m, the P _m-1, P _n belongs plane and H _1, the plane H ₁ to the XY plane and the angle between theta _1.

[0031] 6 dividing point P _m, the P _{m +} 1, P _n belongs plane and H _2, the plane H ₂ is the XY plane and the angle and theta _2.

7. Let R _{1 be} the tool diameter correction amount in the XY plane on the plane H ₁ side, and R ₂ be the tool diameter correction amount in the XY plane on the plane H ₂ side, R ₁ and R ₂ It is obtained from (1) and (2).

R ₁ = r / sin (θ ₁ ) ... (1) R ₂ = r / sin (θ ₂ ) ... (2) The plane H ₁ and the plane H ₂ are as described above. In Fig. 2, the tool radius has been corrected for the upper and lower shapes by r, and the shortage Δr
₁ and Δr ₂ are obtained from the following equations (3) and (4).

Δr ₁ = r / sin (θ ₁ ) −r (3) Δr ₂ = r / sin (θ ₂ ) −r (4) 8 division points P _m-1 And the straight line connecting P _m and L ₁ , the dividing point P _m
And P _{m + 1} linearly and L ₂ connecting the straight line only translated shortage [Delta] r ₁ of the wire-diameter correction amount lines L ₁ in the plane H _u L ₁ ', similarly planar linear L ₂ H _u Let L ₂ ′ be a straight line that is translated by the shortage Δr ₂ of the wire diameter correction amount.

9 An intersection point P _u between the straight line L ₁ ′ and the straight line L ₂ ′ is obtained, and this is set as the wire correction position of the division point P _m .

10 Hereafter, the same processing as in 5 to 9 is performed by dividing point P
_This is performed for _n to obtain the wire correction position P _d of the division point P _n .

A straight line connecting 11 P _u and P _d is the center axis of the wire.

With this correction, even if the width W of the minute curved surface is smaller than the radius r of the wire, tool interference (cutting) does not occur at the inner corner as shown in FIG. It can be tapered.

Next, an embodiment of the taper processing method of the second upper and lower shapes when the wire diameter is changed will be described.

Let r _a be the tool diameter correction amount when the changed wire is in the vertical position, and let R _a be the tool diameter correction amount when tilted by θ with respect to the XY plane during the machining of the vertically different shape. R _a = r _a + (r _a / sin θ−r _a ).

Let _rb be the tool diameter correction amount when the wire before change is in the vertical position, and perform XY during the machining of the vertically different shape.
The tool radius correction amount when tilted by θ with respect to the plane is R _b
Then, R _b = r _b + (r _b / sin θ−r _b ).

In the present invention, (r _a / si of R _a is
The programmed (r _b / sin) of R _b into nθ-r _a )
θ-r _b ) is used to correct r _a by the tool radius correction function (G41, G42) of the NC device. Therefore, although a processing error occurs, when this processing error is G, G = (r _a −r _b ) (1 / sin θ−1).

FIG. 3 shows the machining error G with respect to the difference (r _a −r _b ) in the tool radius correction amount with the inclination angle θ as a parameter. Normally, the inclination angle θ is 7 due to the structural restrictions of the machine.
It is 0 ° or more and the difference in the tool radius correction amount (r _a −r _b ).
Is usually 0.08 mm or less, so the processing error G is 0.0
It is less than 05 mm, which is extremely small.

[0044]

As can be understood from the above description, the taper machining method by the wire cut electric discharge machine according to the first aspect of the present invention has the structure described in claim 1 of the claims, and therefore, it is very small. Even if the width W of the curved surface is made smaller than the radius r of the wire, tool interference (cutting) occurs near the concave surface and the inner corner.
Is less likely to occur. Therefore, highly accurate processing becomes possible.

Further, since the taper machining method of the vertically different shape when the wire diameter of the second invention is changed is provided with the structure described in claim 2 of the claims, the wire diameter is changed. In this case, sufficient machining accuracy can be obtained without changing the machining program, and therefore taper machining becomes easy.

[Brief description of drawings]

FIG. 1 shows a taper machining method using a wire-cut electric discharge machine according to the first invention, wherein (a) is a correction of r and (b) is Δr.
FIG. 6 is an explanatory diagram of the correction of FIG.

FIG. 2 is an explanatory diagram of processing of an inner corner portion of the first invention.

FIG. 3 is an explanatory diagram of a processing error of the second invention.

FIG. 4 is an explanatory diagram of processing of an inner corner portion by a conventional processing method.

FIG. 5 is an explanatory diagram of a tool correction amount.

[Explanation of symbols]

F _u Upper shape F _d Lower shape r r Tool diameter correction amount when the wire is in the vertical position Δr Tool diameter correction amount when the wire is inclined by θ with respect to the XY plane during the machining of the vertically different shape

Claims (2)

[Claims] 1. A method of taper machining a wire in a vertically different shape by a wire-cut electric discharge machine, which comprises correcting the center position of a wire in wire-cut electric discharge machining as follows. 1 The upper shape is F _u , the plane parallel to the XY plane to which the upper shape F _u belongs is H _u , the lower shape is F _d , and the lower shape F _d
Let H _d be a plane parallel to the XY plane to which is belongs. 2 A shape F obtained by correcting the upper shape F _u and the lower shape F _d by the tool radius correction amount r in the respective planes H _u and H _{d to} which they belong.
_{Find u} ′ and F _d ′. 3 Shapes F _u ′ and F _d ′ are equally divided. 4 P _m is an arbitrary division point of the shape F _u ′, and P is an adjacent division point.
It is assumed that _{m + 1} and P _m−1 , the corresponding division points of the shape F _d ′ are P _n , and the adjacent division points are P _{n + 1} and P _n−1 . 5 the dividing point P _m, the P _m-1, P _n belongs plane and H _1, the plane H ₁ is the XY plane and the angle and theta _1. The plane to which the six division points P _m , P _{m + 1} , and P _n belong is H _2, and the angle between the plane H _{2 and the} XY plane is θ ₂ . (7) The shortages Δr ₁ and Δr ₂ of the tool radius correction amount in the XY plane based on the taper of the planes H ₁ and H ₂ are obtained from the following equations (3) and (4). Δr ₁ = r / sin (θ ₁ ) −r (3) Δr ₂ = r / sin (θ ₂ ) −r (4) 8 division points P _m-1 and P _m The straight line connecting the lines is L ₁ , the dividing point P _m
And P _{m + 1} the straight line connecting the L _2, a straight line translated by shortage [Delta] r ₁ of the tool diameter compensation amount a straight line L ₁ in the plane H _u L ₁ ', similarly planar linear L ₂ H _u Let L ₂ ′ be a straight line that is translated by the shortage Δr ₂ of the tool radius correction amount. 9 The intersection point P _u of the straight line L ₁ ′ and the straight line L ₂ ′ is obtained and set as the wire correction position of the division point P _m . The same process as 10 or less 5-9 performs the dividing point P _n, obtains the wire corrected position P _d of the dividing points P _n. The straight line connecting 11 P _u and P _d is the central axis of the wire. 2. In the taper processing of products having different top and bottom shapes,
When changing the wire diameter for machining, use the program for the Δr part of the tool diameter correction amount R = r / sin θ = r + Δr before the change as it is to correct the Δr part of the changed wire. The correction of the r part of the wire is performed by the tool diameter correction function (G41, G42) of the NC device.