JPH0783968B2 - Machining control method for wire cut electric discharge machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a machining control method for a wire cut electric discharge machine, and more specifically, machining of a corner portion with high accuracy by a desired bending angle and cutting. It relates to a control method.

(Prior Art) Conventionally, when a corner portion is machined by a wire cut electric discharge machine, when the trajectory on the program reaches a change point of the corner portion, the direction is changed to proceed the electric discharge machining.

(Problems to be Solved by the Invention) When electric discharge machining is performed by a wire cut electric discharge machine, it is known that the wire electrode is bent (curved) such that the rear side in the traveling direction is convex. Due to the bending of the wire electrode, sagging occurs in the corner portion when processing the corner portion. In order to eliminate this sagging,
There is also a control method of temporarily stopping the relative progress at the corner portion, but in this case, there is a problem that the discharge gap becomes large, which is not satisfactory.

(Means for Solving the Problems) In view of the conventional problems as described above, the present invention is directed to a case where the machining is performed under the normal machining condition (A) up to the course change point on the program of the wire electrode in the corner portion. 1 step,
When the center of the wire electrode guide fixed to the wire electrode positioning device reaches the course change point, the feed of the positioning device is stopped at 1 o'clock and the processing condition is set to the first condition.
A second step of changing the second machining condition (B) capable of maintaining the same gap as the discharge gap of the machining condition (A) and advancing the machining until the wire electrode reaches the course change point; A third step of changing the course angle when reaching the change point and changing to the third processing condition (C) in which the deflection of the wire electrode is smaller than the first processing condition (A), and the processing is advanced, Under the third processing conditions, the following formula l = (d / 2 + G) / (tan θ / 2) where d; diameter of wire electrode (powder) G; discharge gap (powder) θ; distance determined by azimuth angle (degree) The machining control method comprises a fourth step of returning the machining to the first machining condition (A) and returning to the machining of the straight line portion after the machining is advanced by l.

(Embodiment) FIG. 1 is a front view of a wire-cut electric discharge machine 1 embodying the present invention, in which a material W to be processed is a case 3 surrounded by a four-sided transparent plate for preventing scattering of machining liquid. It is gripped by the vice device 5 and is moved together with the table 7 numerically in the X-axis and Y-axis directions.

On the other hand, the wire electrode 9 is, for example, a thin bare conductive wire, which hangs down from the reel 11 through a large number of pulley groups 13 at the center of the nozzle 15 and penetrates through the workpiece W and is guided.

Under the work material W, the discharged electrodes are guided by the pulley group 17 and wound on the reel 19 on the right side in FIG.

A group of pulleys near the reel 11 for unwinding the wire electrode 9
A wire 13 exerts a braking action on the wire electrode 9 to give a tension to the electrode, and it always descends vertically from the center of the nozzle 15 when no load is applied.

A program in which the wire electrode 9 linearly discharges the workpiece W according to FIG. 2 and moves leftward from the point A toward the point B, for example, changes the traveling direction 90 degrees right at the point B and proceeds to the point C. Will be described by using a numerical control positioning device (not shown) on the table 7.

Of course, in the wire cut electric discharge machine 1 shown in FIG. 1, the wire electrode 9 does not change its position in the X and Y axis directions, and the workpiece W
Although the wire electrode 9 moves, the wire electrode 9 moves because it can be explained by the same theory.

The circle around the point A in FIG. 2 is the cross section of the wire electrode 9,
There is a gap G between the workpiece W and the workpiece.

This gap G also occurs on the front side of the wire electrode 9 as is apparent from the left end of FIG. 4, and if the normal movement of the wire electrode 9 relative to the workpiece W is performed, the gap G is the same. It becomes a dimension.

By the way, when machining a corner part with the wire-cut electric discharge machine 1, the path through the center of the wire on the program is A
When the center of the nozzle 15 reaches the point B of the corner of the corner, the wire electrode 9 receives a reaction force due to the electric discharge machining of the workpiece W and is slightly delayed B '. It is located at a point.

Therefore, when the course is changed without taking into account the above-mentioned delay or bending (curvature) as in the conventional case, the route of the wire electrode 9 advances to B'C as shown by the dotted line, and the discharge kerf 21 is sloped inside and outside the corner portion. Produces 23.

In the machining control method of the present invention, unlike the above-mentioned conventional method, the same normal machining as the straight line portion is performed until the center of the nozzle 15 which is the course change point on the program of the wire electrode 9 reaches the point B as the first step. Processing proceeds under the condition (A).

Next, when the center of the wire electrode guide (nozzle 15) reaches the course changing point B, the feed of the positioning device (table 7) is stopped at 1 o'clock, and the machining condition is the discharge gap of the first machining condition (A) described above. The second process is advanced by changing the second processing condition (B) in which the voltage is lowered so that the same amount of gap G as G can be obtained also on the straight-travel end side.

As the second step progresses, as shown in FIG. 3, the center of the wire electrode 9 comes to coincide with the course changing point B on the program.

Next, the center of the wire electrode 9 is the course change point B on the program.
If it coincides with the above, electric discharge is not generated, so that the course is immediately changed and the machining is performed by changing to the low voltage machining condition (C) that causes less bending or delay of the wire electrode 9 than the first machining condition (A) described above. The third step is carried out.

In this third step, as shown in FIG. 5, until the center of the wire electrode 9 reaches the edge line of the discharge kerf 21, the oblique reaction force indicated by P acts, so this reaction force It is designed to keep the value small.

That is, since there is a cross-hatched single load portion 25 in FIG. 5, the discharge work is carried out under the third working condition (C) in which the deflection of the wire electrode is smaller than that in the first working condition (A).

Further, as is clear from the above description, the distance 1 for advancing the machining under the third machining condition (C) is the wire electrode 9 from the time when the course is changed as apparent from FIGS. 3 and 4.
Until the center of reaches the end of the electric discharge kerf that has been processed.

That is, the distance 1 can be calculated by l = (d / 2 + G) / (tan θ / 2), where d is the diameter of the wire electrode (powder) G; the discharge gap (powder) θ;

After advancing the distance 1 under the third machining condition (C), the machining is advanced by returning to the first machining condition (A) for the first linear portion machining.

(Effects of the Invention) As will be understood from the above description of the embodiment, in short, the present invention advances processing under normal processing conditions (A) up to the course change point on the program of the wire electrode at the corner portion. First step: When the center of the wire electrode guide fixed to the wire electrode positioning device reaches the course change point, the positioning device feed is stopped for one hour and the machining condition is set to the first machining condition (A). The second step of changing the second machining condition (B) capable of maintaining the same gap as the discharge gap of (1) and advancing the machining until the wire electrode reaches the course changing point; And a third step (C) in which the path angle is changed and the deflection of the wire electrode is smaller than that in the first processing condition (A), and the processing is advanced: Under the processing conditions of No. 3, the following formula: l = (d / 2 + G) / (tan θ / 2) where d; diameter of wire electrode (powder) G; discharge gap (powder) θ; distance l determined by azimuth angle (degree) The machining control method for the wire-cut electric discharge machine comprises: a fourth step of returning the machining to the first machining condition (A) and then returning to machining of the straight line portion after the machining is advanced.

As is clear from the above configuration, in the present invention, when the electric discharge machining is performed under the normal machining condition (A) (first step), and the center of the wire electrode guide for guiding the wire electrode reaches the course changing point. Feeding is temporarily stopped and processing conditions (A)
The machining condition is changed to the second machining condition (B) capable of maintaining the same discharge gap as that of No. 2 and the machining is continued until the wire electrode reaches the course changing point (second step).

Then, when the wire electrode reaches the course changing point, no electric discharge is generated, so that the course angle is changed immediately and the bending of the wire electrode becomes smaller than that of the first processing condition (A). The machining condition (C) is changed to the machining condition (third step), and after the machining is advanced by the distance l represented by the predetermined formula, the machining condition is changed to the first machining condition (A) to Processing is performed (fourth step).

That is, in the present invention, the path angle is changed when both the center of the wire electrode guide and the wire electrode reach the path changing point, and the processing at this time is performed under the third processing condition.

Therefore, according to the present invention, when the path angle is changed, both the center of the wire electrode guide and the wire electrode coincide with the path change point, and accurate electric discharge machining is performed without sagging at the corners. Is something that can be done.

[Brief description of drawings]

FIG. 1 is a front view of a wire-cut electric discharge machine as an embodiment, FIG. 2 is an explanatory view of a route change point vicinity, FIG. 3 is the same as above and an explanatory view of a third processing condition execution distance l, and FIG. Same as FIG. 3, except that the course change angle is 90 degrees or more, and FIG. 5 is an explanatory view of the reaction force by the one-side load portion. (Explanation of the symbols indicating the main parts of the drawing) 1 …… Wire cut electric discharge machine 9 …… Wire electrode, 15 …… Coolant nozzle W …… Workpiece material, 21 …… Discharge kerf 23 …… Drop portion, 25 ... Single load part

Claims (1)

[Claims] 1. A machining control method for a wire cut electric discharge machine, comprising the following steps. (A) A first step in which machining is performed under normal machining conditions (A) up to the course change point on the wire electrode program in the corner portion. (B) When the center of the wire electrode guide fixed to the wire electrode positioning device reaches the course changing point, the positioning device feed is stopped for one hour and the machining condition is set to the first machining condition (A). A second step of changing the second processing condition (B) capable of maintaining the same gap as the discharge gap and advancing the processing until the wire electrode reaches the course changing point. (C) A third processing condition (C) in which the path angle is changed when the wire electrode reaches the path change point and the deflection of the wire electrode is smaller than that in the first processing condition (A).
The third step that changes to and advances the processing. (D) The following formula under the above-mentioned third processing conditions: l = (d / 2 + G) / (tan θ / 2) where d; diameter of wire electrode (powder) G; discharge gap (powder) θ; azimuth (degree) A fourth step in which the machining is advanced by the distance 1 defined in 1. and then the machining is returned to the machining of the straight line portion by returning to the first machining condition (A).