JP2571077B2 - Control method of wire electric discharge machining - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a control of wire electric discharge machining in which a discharge is generated between a traveling wire electrode and a work, that is, a workpiece, and the workpiece is discharged by discharge energy. About the method.

[Conventional technology]

Conventionally, in a wire electric discharge machine, at present, a workpiece is machined using a portion in which a wire electrode runs in a vertical direction, in other words, a vertical direction. The wire electrode is guided by a roller fixed to the main body of the wire electric discharge machine, and is supplied to a wire head having a wire guide. On the other hand, the table on which the workpiece is mounted moves in the X and Y directions according to the processing state of the workpiece according to a command from the NC device, and performs servo movement, that is, servo movement between the wire electrode supplied to the wire head. Processing proceeds by repeating the function. In other words, the wire head not only advances relatively in the machining direction during electric discharge machining to the wire,
When the electric discharge machining becomes unstable in accordance with the state of the machining waste or the like, the electric discharge machining also retreats along the machining locus for an instant to eliminate the short circuit.
Next, the electric discharge machining is performed again. Then, in response to a command from the NC device, the workpiece moves in the horizontal direction, that is, in the X and Y directions, and the movements of the two are combined, and the workpiece is discharged into a predetermined machining shape by the relative movement of the two. It has been processed.

In this wire electric discharge machine, when performing wire electric discharge machining on a workpiece, for example, when the machining conditions are not changed in a bending portion such as a corner, a shape error generated in a corner such as a corner becomes large. For example, as shown in FIG. 11, when the workpiece 2 is subjected to electric discharge machining by the wire electrode 1 into a refraction shape, at the corner CP which is the refraction point, a shape error 12 such as drooping or biting of the outer corner of the workpiece 2 is obtained. In addition, a shape error 13 such as an unretained inner corner portion or unprocessed portion occurs. Especially,
In the rough machining area, the amount of the shape errors 12 and 13 becomes large and remarkable. However, as shown in FIG. 12, the wire electrode 1 is connected to the die guide member 15 in the upper wire head.
And the wire which is supported by the die guide member 16 in the lower wire head, due to a repulsive force due to a discharge generated between the wire electrode 1 and the workpiece 2, the wire as the wire electrode 1 bends, Workpiece 2 due to its bending
Is not electric-discharge machined along a predetermined machining line 14, and a shape error 12 such as a bite and a shape error 13 such as an unprocessed portion occur.

[Problems to be solved by the invention]

In products produced by wire electric discharge machining, for example, various molds, jigs and tools, and components, the higher the required accuracy thereof, the more problematic the occurrence of corner shape errors such as corners of a workpiece. In recent years, in particular, demands for higher precision and higher quality have been increasing, and it is necessary to meet these demands. Conventionally, in the control method of the wire electric discharge machining, since the control for changing the machining condition is started after reaching the intersection or the contact point of the corner, the delay due to the bending of the wire of the wire electrode cannot be sufficiently corrected. In addition, the effect of changing the processing conditions cannot be achieved accurately and quickly. Also, machining the same trajectory several times with the same program,
The second cut method, which can be finished with high precision, is disclosed as a general processing technique, but this second cut method requires time and effort, is labor-saving, and has problems in terms of improving productivity. have.

Also, in the conventional EDM of a workpiece, if only the machining conditions are changed at a very small distance before the corner, and if it is not gradually changed gradually, the wire of the wire electrode before and after the corner bends, Therefore, the amount of deflection of the wire increases, the amount of biting of the wire electrode in the corner area increases, or the amount of remaining machining increases, and the machining shape of the workpiece can be adjusted with high accuracy according to a preset program. Phenomenon that cannot be processed occurs.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, and when a workpiece is subjected to electrical discharge machining by applying a voltage between the wire electrode and the workpiece, a bent portion or a bent portion is formed on a machined figure. Provided is a wire electric discharge machining control method capable of achieving a high-speed machining and a high-precision machining capable of obtaining a desired machining shape by minimizing a shape error of a portion of the corner when a corner such as this exists. It is.

[Means for solving the problem]

The present invention is configured as follows in order to solve the above problems and achieve the above object. That is, the present invention relates to a wire electric discharge machining control method in which a gap voltage is applied between a wire electrode and a workpiece to perform electrical discharge machining on the workpiece. In response to the existence, the machining condition is continuously changed stepwise over a plurality of stages at every minute movement distance of about 0.005 mm to 0.1 mm at the minute distance before and after the corner, and the minute distance before and after the corner is changed. The present invention relates to a control method for wire electric discharge machining, wherein electric discharge machining is performed on the workpiece by performing control for continuously continuing wire electric discharge machining without stopping feed of the wire electrode.

In the control method of the wire electric discharge machining, the machining conditions include a machining speed, a gap voltage, a discharge time, a discharge pause time, and a wire electrode tension.

Further, in this control method of wire electric discharge machining, the corner is a connection point between a straight line and a straight line, a straight line and an arc curve, or an arc curve and an arc curve.

[Action]

The control method of the wire electric discharge machining according to the present invention is configured as described above, and operates as follows. That is, in the present invention, when there is a corner such as a bent portion or a bent portion in a predetermined processed figure, the processing condition is changed at a minute distance before and after the corner, for example, the wire tension of the wire electrode is changed. Control to prevent electric wire bending, reduce machining speed to adjust to desired machining speed, increase pulse pause time, or increase applied voltage to perform electric discharge machining Thus, the electric discharge machining can be accurately and quickly performed on the machining shape of the corner such as the bent portion or the bent portion such as the corner portion where the electric discharge machining has been performed, according to a preset program.

Since the control method of the wire electric discharge machining according to the present invention, as described above, the machining condition is continuously changed stepwise over a plurality of stages at a movement distance of about 0.005 mm to 0.1 mm at a minute distance before and after the corner. The amount of deflection of the wire of the wire electrode before and after the corner is reduced, thereby reducing the amount of bite at the corner, reducing the remaining machining amount, and enabling the machining shape of the workpiece to be precisely controlled according to a preset program. Can be processed.

〔Example〕

Hereinafter, an embodiment of a control device for a wire electric discharge machine according to the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 2 are explanatory views for explaining a method of controlling wire electric discharge machining according to the present invention. FIG. 1 is an operation diagram showing a relationship between a wire electrode 1 and a workpiece 2, and FIG. FIG. 3 is a graph showing a change in processing conditions accompanying movement of the wire electrode 1. Generally, in a wire electric discharge machine,
A workpiece, that is, a workpiece 2 is installed on the workpiece mounting table,
The workpiece mount is configured to be movable in a horizontal direction. That is, the work mounting table on which the work 2 is mounted is moved in accordance with the processing status of the work 2 by a command from the NC device.
The servo movement is repeatedly advanced by a servo feed mechanism driven by a servo motor between the wire electrode 1 supplied to the wire head and the wire electrode 1 supplied to the wire head. The object 2 is subjected to electric discharge machining into a predetermined machining shape. Further, wire heads are provided above and below the workpiece 2, and these wire heads are provided with a power supply, a power supply holding member, a die guide member,
It consists of a working fluid injection nozzle and the like. Wire electrode 1 sent from an automatic wire feeder or the like via a roller guide or the like
The winding reel passes through the die guide member installed in the inner cylinder of the upper wire head, passes through the die guide member installed in the inner cylinder of the lower wire head after subjecting the workpiece 2 to electrical discharge machining, and It is discharged to the wire reservoir.

A method for controlling wire electric discharge machining according to the present invention using the above-described wire electric discharge machine has the following configuration. The control method of this wire electric discharge machining includes the wire electrode 1
In the wire electric discharge machining in which the inter-electrode voltage is applied between the workpiece and the workpiece 2 and the workpiece 2 is subjected to electrical discharge machining, when there is a corner CP such as a bent portion or a bent portion in a predetermined machining figure, the corner CP
Minute distance L ₁ before the vehicle and a minute distance after passing through the corner CP
Is characterized in that in L ₂ was controlled so as to perform electric discharge machining by changing the machining conditions. That is, the wire electrode 1 which has signaled in the direction of the arrow W under the normal processing condition NK has a predetermined minute distance L ₁ (i.e., before reaching the 90-degree corner in FIG. 1) before the corner CP (that is, before the corner CP). shape, a predetermined distance L ₁ which is set in accordance with conditions such as the type, for example,
The control of the change of the processing condition is started from 0.1 to 1.0 mm). For example, the tension of the wire electrode 1 is set to an optimum state, and the wire electrode 1 is corrected or adjusted as straightly as possible, The voltage V _G , the machining speed V, and the pulse quiescent time are adjusted to control specific processing conditions SK such that the corner CP such as a corner bends. The electric discharge machining of the work piece 2 is performed while gradually returning the SK to the normal machining condition NK, and a predetermined minute distance L ₂ from the corner CP (that is, a predetermined minute distance L ₂ set in advance according to conditions such as the shape and type of the corner in advance) a distance L _2, for example, 0.2
1.51.5 mm), the processing conditions are controlled so as to return to the normal processing conditions NK. In addition,
It goes without saying that the control of the processing conditions may be performed with either the analog amount or the digital amount.

In the control method of the wire electric discharge machining according to the present invention,
Examples of the processing conditions include the following conditions.

(1) To change the machining speed V of the electric discharge machining for the workpiece 2. Normally, the machining speed V is reduced and the corner CP
In this case, of course, the processing speed V is set in advance according to conditions such as the shape of the corner, the type of curve such as a straight line or an arc, the material, etc. It is sufficient if the setting is made to reduce the processing speed to at least about 50%.

(2) is to change the inter-electrode voltage V _G applied between the wire electrode 1 and the workpiece 2. Usually, which pass through the corner CP by increasing the inter-electrode voltage V _G, in this case,
Of course, the shape of the pre-corner type such as curves such as lines and arcs, although polar voltage V _G according to the conditions of the material, such as those to be set to about 500% maximum than the normal inter-electrode voltage It is enough to set it to increase to.

(3) Changing the duty factor by changing the pulse width and the pause time, or changing the discharge time. Usually, the pause time OFF is increased to pass through the corner CP. In this case, of course, the pause time is determined in advance according to the shape of the corner, the type of curve such as a straight line or an arc, the material, and the like. Although OFF is set, it is sufficient to set it so that it is increased up to about 500% at most than the normal pause time.

(4) To change the tension WT of the wire electrode 1. Usually, the tension WT of the wire electrode 1 is increased to pass through the corner CP. In this case, of course,
The tension WT of the wire electrode 1 is set in advance in accordance with conditions such as the shape of the corner, the type of curve such as a straight line or an arc, the material, etc. Setting it to increase to 200% is sufficient.

Further, the method for controlling the processing conditions may be either a stepless method or a step method, but if the method is a step method, for example, about 30 steps, and the moving distance of each step is about 0.00.
It can be set to 5 to 0.1 mm depending on the shape of the corner, the type of curve such as a straight line or an arc, the material, and the like. FIG. 1 shows a case where the processing conditions are changed in a stepwise manner.

Further, regarding the corner CP such as the bent portion and the bent portion, for example, the intersection point and the contact point (intersecting line, tangent line, intersecting circle, Tangent circle).

Next, an example of the operation of the control method for wire electric discharge machining according to the present invention will be described with reference to FIGS. 3 to 9 and flowcharts shown in FIGS. 10 (A), 10 (B) and 10 (C). , Tenth
This will be described with reference to FIG. 10 (D), FIG. 10 (E) and FIG. 10 (F). The operation described here is an example of a preferable operation, and it goes without saying that the control method of the wire electric discharge machining according to the present invention is not limited to this operation.

First, the start of the operation of the wire electric discharge machining control method according to the present invention will be described with reference to FIG. 10 (A). Turn on the operation switch of the wire electric discharge machine,
The wire supply device, the working fluid supply device and the like are operated (step 20). A gap voltage is applied between the workpiece and the wire electrode, and the workpiece is subjected to electrical discharge machining under the normal machining condition NK (step 21). Electric discharge machining is continuously performed on the workpiece based on the normal machining conditions NK while detecting the position where the machining is performed by a predetermined figure, machining trajectory, sensor, or the like to be subjected to electrical discharge machining on the workpiece (step 22). . Therefore, the following processing is performed in order to recognize what kind of figure is the corner CP to be subjected to electric discharge machining next.

As shown in FIG. 3, it is determined from a previously input processed graphic whether or not the shape of the processed graphic is a corner CP in the case of an intersection line refracting from a straight line to a straight line at a refraction angle θ (step 2).
3) In the case of a straight-to-straight corner CP, proceed to Step 24; otherwise, proceed to Step 36. Then
In the case of a straight corner to a straight corner CP, it is determined in advance from the machining figure to be subjected to electric discharge machining whether or not the refraction angle θ is equal to or less than 150 °. It is determined that it is necessary to change the processing condition from the normal processing condition NK to the predetermined specific processing condition SK in the range (step 24). Then, the electric discharge machining of the workpiece is performed under the normal machining condition NK. Refraction angle θ
If you need to change the processing conditions below 150 ゜
Before the minute distance of the preset corner CP according to the machining shape, i.e. machining position is determined whether the host vehicle has reached the predetermined distance L ₁ in front of the corner CP (step 25).

Then, the processing position when detecting the arrival at the predetermined distance L ₁ starts to change the machining conditions according to the specific processing conditions SK which is set in advance in accordance with the refraction angle of the straight line θ from the straight line (step 26) . At this time, as for the control of the change of the processing condition, as shown in FIG. 2, the change is continued so as to gradually approach the specific processing condition SK, and the control is performed so that the degree of change becomes maximum at the corner CP ( Steps
27). Next, it is determined whether or not the corner CP has been reached. If the corner CP has not been reached, the machining conditions are continuously changed to perform the electric discharge machining, and the position of the electric discharge machining is changed to the corner CP.
When the CP is reached, the process proceeds to the next step 29 (step 28).

When the position of the electric discharge machining reaches the corner CP, as shown in FIG. 2, control is started so as to return from the specific machining condition SK to the normal machining condition NK (step 29). Discharge machining is changed so as to be close to the normal processing conditions NK gradually specific processing conditions SK until a passing distance L ₂ which is set in advance from the corner CP, is controlled to be in the normal processing conditions NK In passing distance L ₂ (Step 30). Position of the electric discharge machining is determined whether reached passing distance L ₂ which passes through the distance L ₂ is set in advance from the corner CP (step 31), subsequently processed. If it is judged a predetermined passing distance L ₂ continuously changing conditions EDM control to perform, when it reaches a predetermined passing distance L ₂ to change to the normal processing conditions NK (step 32).

Next, electric discharge machining is performed under the normal machining condition NK, and the workpiece is machined into a predetermined figure (step 33). It is determined whether finishing of the machined surface of the workpiece or machining has been completed (step 34). If machining has not been completed, the process returns to step 21 to continue electric discharge machining. When the finishing or machining of the electric discharge machining for the workpiece is completed, the operation of the wire electric discharge machine is turned off and the electric discharge machining for the workpiece is terminated (step 35).

Next, if it is not a straight-to-straight corner CP, the process proceeds to step 36, which will be described with reference to FIG. 10 (B). In this case, as shown in FIG. 4, it is determined in advance from the machining figure to be subjected to the electric discharge machining whether or not the corner CP is a tangent circle connecting a straight line to an arc (step 36). In FIG. 4, (A) is a corner CP only in the case of a tangent connecting from a straight line to an arc, and (B) is a tangent connecting from an arc to a straight line after a tangent connecting from a straight line to an arc. Are shown for two corners CP. Next, if it is not a corner CP in the case of a tangent circle connecting a straight line to an arc, the process proceeds to step 46, whereas if it is a corner CP in the case of a tangent circle connecting a straight line to an arc, the process proceeds to step 37. Here, regarding the radius of curvature R of the arc, for example, it is assumed that the radius of curvature R is 5 mm or less, and it is necessary to change the processing condition from the normal processing condition NK to the predetermined specific processing condition SK in this effective range, If the curvature radius R is not less than 5 mm, it is determined that there is no need to change the machining conditions, and the routine proceeds to step 33, where the electric discharge machining of the workpiece is performed under the normal machining conditions NK.

Therefore, it is determined in advance from the machining figure to be subjected to electric discharge machining whether or not the radius of curvature R is 5 mm or less (step 38). If it is necessary to change the machining condition when the radius of curvature R of the arc is 5 mm or less, machining is performed. Corner CP set in advance according to the figure
Before the minute distance of, i.e. machining position is determined whether the host vehicle has reached the predetermined distance L ₁ in front of the corner CP (step 38).
When the working position is detected to reach a predetermined distance L ₁ starts to change to predetermined specific processing conditions SK corresponding to the arc of curvature radius R (step 39). At this time, the control of the change of the processing condition is controlled so as to gradually approach the specific processing condition SK as shown in FIG. 2 so that the degree of change is maximized at the corner CP (step 40). ).

Next, it is determined whether or not the tangent of the straight line and the arc has been reached, that is, whether or not the corner CP has been reached. If the corner has not been reached, the machining conditions are continuously changed to continue the electric discharge machining, and the position of the electric discharge machining is changed. When the vehicle reaches the corner CP, the process proceeds to the next step 42 (step 41). When the position of the electric discharge machining reaches the corner CP, as shown in FIG. 2, control is started so as to return from the specific machining condition SK to the normal machining condition NK (step 4).
2). Passage distance L ₂ that is preset from corner CP by EDM
Modified as close to normal processing conditions NK gradually specific processing conditions SK to reach, it is controlled to be in the normal processing conditions NK In passing distance L ₂ (step 43).

Position of the electric discharge machining is determined whether reached passing distance L ₂ which passes through the distance L ₂ is set in advance from the corner CP (Step 4
4), the electric discharge machining continues continuously changing processing conditions. If it is judged a predetermined passing distance L _2, when it reaches a predetermined passing distance L ₂ to change to the normal processing conditions NK ( Step 45). Next, electric discharge machining is performed under the normal machining condition NK, and the process proceeds to step 33 for machining the workpiece into a predetermined figure.

Next, as shown in FIG. 10 (C), in the case of a non-tangent corner CP connecting a straight line to an arc, the step
In this case, as shown in FIG. 5, in this case, it is determined in advance from the machining figure to be subjected to the electric discharge machining whether or not it is the corner CP in the case of the intersecting circle connecting the straight line to the circular arc (step). 46). Next, if it is not a corner CP in the case of an intersecting circle connecting a straight line to an arc, the process proceeds to step 56, but if it is a corner CP in the case of an intersecting circle connecting a straight line to an arc, then the refraction angle Whether θ is, for example, 150 ° or less is detected in advance from a machining figure to be subjected to electric discharge machining, and if it is 150 ° or less, it is determined to be valid. It is assumed that the machining condition needs to be changed to the condition SK, and if it is not less than 150 °, it is assumed that the machining condition does not need to be changed. . Therefore, it is determined in advance whether or not the refraction angle θ is equal to or less than 150 ° from a machining figure to be subjected to electric discharge machining (step 47). the front of the small distance of a preset corners CP according to the machining shape, i.e. machining position is determined whether the host vehicle has reached the predetermined distance L ₁ in front of the corner CP (step 48).

Working position when it is detected that has reached a predetermined distance L ₁ starts to change to predetermined specific processing conditions SK from the straight line corresponding to the arc angle of refraction theta (Step 4
9). In this case, the radius of curvature R of the arc is not limited. At this time, as for the control of the change of the processing condition, as shown in FIG. 2, the control is changed so as to gradually approach the specific processing condition SK so that the degree of change is maximized at the corner CP (step 50). ). Next, it is determined whether or not the intersection circle of the straight line and the arc, that is, the corner CP has been reached (step 51). If the corner CP has not been reached, the machining conditions are continuously changed to continue the electric discharge machining, and the electric discharge machining is performed. When the processing position reaches the corner CP, the process proceeds to the next step 52.

When the position of the electric discharge machining reaches the corner CP, as shown in FIG. 2, control is started so as to return from the specific machining condition SK to the normal machining condition NK (step 52). Discharge machining is changed so as to be close to the normal processing conditions NK gradually specific processing conditions SK until a passing distance L ₂ which is set in advance from the corner CP, is controlled to be in the normal processing conditions NK In passing distance L ₂ (Step 53). Position of the electric discharge machining is determined whether reached passing distance L ₂ which passes through the distance L ₂ is set in advance from the corner CP (step 54), subsequently processed. If it is judged a predetermined passing distance L ₂ performed intermittently to discharge machining the variations of the conditions usually change the machining conditions NK when it reaches a predetermined passing distance L ₂ (step 55). Next, the electric discharge machining is performed under the normal machining condition NK, and the process proceeds to step 33 in order to machine the workpiece into a predetermined machining figure.

In the next processing stage, if the straight line is not connected to the circular arc at the corner CP which is not an intersecting circle, the process proceeds to step 56. This case will be described with reference to FIG. 10 (D). In this case, as shown in FIG. 6, it is determined in advance from the machining figure to be subjected to electric discharge machining whether or not it is a tangent connecting a straight line from an arc (step 56). If it is a tangent that connects a straight line from an arc, the normal processing conditions
Even if electrical discharge machining is performed with NK, no bite or no machining at the corner CP occurs.Therefore, it is assumed that there is no need to change the machining conditions in this case, and electric discharge machining is normally performed with NK. And the process proceeds to step 33
Proceed to. If the tangent is not a tangent connecting the arc to the straight line, the process proceeds to step 57.
As shown in the figure, it is determined in advance from the machining figure to be subjected to electric discharge machining whether or not the corner CP is in the case of the intersection line connecting the arc to the straight line (step 57). In the case of the corner CP in which the intersection is not an intersection connecting the arc to the straight line, the process proceeds to step 67. Next, in the case of a corner CP in the case of an intersection line connecting a circular arc to a straight line, if the refraction angle θ is, for example, 150 ° or less, it is valid, and in this effective range, a predetermined specific It is assumed that it is necessary to change the machining condition to the machining condition SK, and if it is not less than 150 mm, it is assumed that the machining condition does not need to be changed.The process proceeds to step 33 and the electric discharge machining of the workpiece is performed under the normal machining condition NK. ,
Therefore, it is determined in advance whether or not the refraction angle θ is equal to or less than 150 ° from a machining figure to be subjected to electric discharge machining (step 5
8) If it is necessary to change the machining conditions when the refraction angle θ of the intersection line connecting the arc to the straight line is 150 ° or less, the minute distance before the corner CP set in advance according to the machining figure,
That processing position determines whether the host vehicle has reached the predetermined distance L ₁ in front of the corner CP (step 59).

Processing position within when it detects that it has reached a predetermined distance L _1, it begins to change to a specific processing conditions SK which is set in advance in accordance with the refraction angle θ from the arc of linear intersection line (step 60). In this case, it is assumed that there is no restriction on the radius of curvature of the arc in front. At this time, as for the control of the change of the processing condition, as shown in FIG. 2, the specific processing condition SK is changed so as to gradually approach and the control is performed so that the degree of the change becomes maximum at the corner CP (step 61). ). Next, it is determined whether or not the intersection of the arc and the straight line, that is, the corner CP has been reached (step 62). If the corner CP has not been reached, the machining conditions are continuously changed to continue the electric discharge machining, and the electric discharge machining is performed. When the processing position reaches the corner CP, the process proceeds to the next step 63.

When the position of the electric discharge machining reaches the corner CP, control is started so as to return from the specific machining condition SK to the normal machining condition NK as shown in FIG. 2 (step 63). Discharge machining is changed so as to be close to the normal processing conditions NK gradually specific processing conditions SK until a passing distance L ₂ which is set in advance from the corner CP, is controlled to be in the normal processing conditions NK In passing distance L ₂ (Step 64). Position of the electric discharge machining is determined whether reached passing distance L ₂ which passes through the distance L ₂ is set in advance from the corner CP (step 65), subsequently processed. If it is judged a predetermined passing distance L ₂ performed continuously by electric discharge machining to change the conditions usually change the machining conditions NK when it reaches a predetermined passing distance L ₂ (step 66). Next, the electric discharge machining is performed under the normal machining condition NK, and the process proceeds to step 33 in order to machine the workpiece into a predetermined figure.

Next, if it is not the corner CP of the straight line from the arc, the process proceeds to step 67. This case will be described with reference to FIG. 10 (E). In this case, as shown in FIG. 8, it is determined in advance from the machining figure to be subjected to the electric discharge machining whether or not the corner CP is in the case of the tangent circle connecting the arcs (step 67). In FIG. 8, (A) shows a corner CP when a tangent circle connected from an arc to the arc advances in the opposite direction.
(B) shows a corner CP in a case where tangent circles connected from an arc to the arc advance in the same direction. For the subsequent arc in this case, for the radius of curvature R, for example, it is assumed that the radius of curvature R is 5 mm or less, and the normal processing condition NK must be set to the predetermined specific processing condition SK in this effective range. There is no limitation on the radius of curvature of the arc in front.

Next, the corner in the case of the tangent connecting the arc to the arc
If it is not a CP, the process proceeds to step 77, but in the case of a corner CP in the case of a tangent connecting from an arc to an arc, a radius of curvature R of the arc of 5 mm or less is effective, and normal machining is performed in this effective range. It is assumed that it is necessary to change the processing condition from the condition NK to the predetermined specific processing condition SK, and the curvature radius R is 5 m
If it is not less than m, it is determined that there is no need to change the machining conditions, and the process proceeds to step 33 to perform the electric discharge machining of the workpiece under the normal machining condition NK, where the radius of curvature R of the arc is 5 m.
m is determined in advance from the machining figure to be subjected to electric discharge machining (step 68). If the radius of curvature R of the arc is 5 mm or less and machining conditions need to be changed, the machining conditions are changed according to the machining figure. before the minute distance of the preset corner CP, i.e. machining position is determined whether the host vehicle has reached the predetermined distance L ₁ in front of the corner CP (step 69). Processing position is a predetermined distance L ₁
When it has been detected that the processing condition has reached, the process is started to change to the preset specific machining condition SK corresponding to the radius of curvature R of the arc (step 70).

At this time, the control of the change of the processing condition is controlled so as to gradually approach the specific processing condition SK as shown in FIG. 2 so that the degree of change is maximized at the corner CP (step 71). ). Next, it is determined whether or not the tangent between the arcs, that is, the corner CP has been reached (step 72).
If the electric discharge machining has not reached the corner CP, the machining conditions are continuously changed to perform electric discharge machining. When the electric discharge machining position reaches the corner CP, the process proceeds to the next step 73.

When the position of the electric discharge machining reaches the corner CP, control is started so as to return from the specific machining condition SK to the normal machining condition NK as shown in FIG. 2 (step 73). Discharge machining is changed so as to be close to the normal processing conditions NK gradually specific processing conditions SK until reaching the passing distance L ₂ which is set in advance from the corner CP, controlled to a normal machining condition NK In passing distance L ₂ (Step 74). EDM position is corner CP
Passing distance L _2, it is judged whether the reached passing distance L ₂ to a preset from (step 75), and change the continued processing conditions when it does not reach the predetermined passing distance L _2, predetermined Usually it changes the processing conditions NK when it reaches the passing distance L ₂ (step 76). Next, electric discharge machining is performed under the normal machining condition NK, and the process proceeds to step 33 for machining the workpiece into a predetermined figure.

Next, as shown in FIG. 10 (F), in the case of a non-tangent corner CP connecting the arcs to the arc, the step
Going to 77, in this case, it is determined in advance from the machining figure to be subjected to electric discharge machining whether or not it is a corner CP in the case of an intersecting circle connecting arcs as shown in FIG. 9 (step 77). ). FIG. 9 shows a corner CP in the case of an intersecting circle connected from an arc to an arc, where (A) travels in the same direction and (B) travels in the opposite direction. For the refraction angle θ in this case, for example, 150 ° or less is effective, and in this effective range, it is necessary to set the normal processing condition NK to a predetermined specific processing condition SK. _1, the R ₂ is that there is no limit.

By the way, the corner CP in the case where the arc is not an intersecting circle connected from the arc to the arc does not apply to any of the corner CPs described above, and in this wire electric discharge machining control method, it is not necessary to change the machining conditions. Is a step
Proceed to 33. Also, in the case of a corner CP in the case of an intersecting circle connected from an arc to an arc, if the refraction angle θ is, for example, 150 ° or less, it is valid, and a predetermined specific It is assumed that the machining condition needs to be changed to the machining condition SK, and if the refraction angle θ is not less than 150 °, the machining condition does not need to be changed. Then, it is determined in advance whether or not the refraction angle θ is equal to or less than 150 ° from a machining figure to be subjected to electric discharge machining (step 78), and the machining condition is changed when the refraction angle θ is equal to or less than 150 °. If necessary, the front of the small distance of a preset corners CP according to the machining shape, i.e. machining position is determined whether the host vehicle has reached the predetermined distance L ₁ in front of the corner CP (step 79) .

Working position when it is detected that has reached a predetermined distance L ₁ starts to change to a particular processing conditions SK from arc preset corresponding to an arc angle of refraction theta (Step 8
0). At this time, regarding the control of the change of the processing condition,
As shown in the figure, the control is changed so as to gradually approach the specific processing condition SK, and control is performed so that the degree of change becomes maximum at the corner CP (step 81). Next, it is determined whether or not the intersection of the arcs, that is, the corner CP has been reached (step 8).
2) If it has not reached the corner CP, the machining conditions are continuously changed to perform electric discharge machining. When the position of the electric discharge machining reaches the corner CP, the process proceeds to the next step 83.

When the position of the electric discharge machining reaches the corner CP, control is started so as to return from the specific machining condition SK to the normal machining condition NK as shown in FIG. 2 (step 83). Discharge machining is changed so as to be close to the normal processing conditions NK gradually specific processing conditions SK until a passing distance L ₂ which is set in advance from the corner CP, is controlled to be in the normal processing conditions NK In passing distance L ₂ (Step 84). Position of the electric discharge machining is determined whether reached passing distance L ₂ which passes through the distance L ₂ is set in advance from the corner CP (step 85), subsequently processed. If it is judged a predetermined passing distance L ₂ performed continuously by electric discharge machining to change the conditions usually change the machining conditions NK when it reaches a predetermined passing distance L ₂ (step 86). Next, the electric discharge machining is performed under the normal machining condition NK, and the process proceeds to step 33 in order to machine the workpiece into a predetermined figure.

The control method of the wire electric discharge machining according to the present invention is operated as described above, but is not necessarily limited to the above embodiment. For example, in the above embodiment, the normal processing conditions
The state where NK was changed to the specific processing condition SK was controlled so that the change state was maximized at the corner CP position, but in some cases, the state was controlled so that it was maximized short of the corner position, and continued. It is of course possible to control the electric discharge machining of the workpiece under the maximum specific machining conditions, and to start changing the machining conditions so as to return to the normal machining conditions from a very small distance after passing through the corner position. is there.

〔The invention's effect〕

The wire electric discharge control method according to the present invention is configured as described above, and has the following effects. That is, in the present invention, when there is a corner such as a bent portion, a bent portion, or the like in a predetermined processed figure, the processing condition is set at a small distance before and after the corner over a plurality of steps every moving distance of about 0.005 mm to 0.1 mm. Since the control is performed so as to continuously change in a stepwise manner, the tension of the wire electrode is set in an optimum state so that the wire electrode does not bend (phenomenon does not occur and the wire does not break). In other words, the wire can be controlled so as not to cause bending or disconnection, and the bent portion such as a corner portion subjected to electric discharge machining, the processed shape of a corner such as a bent portion can be reliably and precisely finished according to a preset program, There is no need to perform a second cut, etc., which can increase the machining speed of electric discharge machining of the workpiece, increase productivity, and save labor, and therefore, can achieve high-speed machining and high precision machining. Not only can be realized,
Product quality can be improved.

That is, in the wire electric discharge machining, when the machining condition is gradually controlled so as to be continuously changed stepwise over a plurality of stages at a minute distance before and after the corner at every moving distance of about 0.005 mm to 0.1 mm, the wire of the wire electrode Deflection is almost eliminated, and undesired biting of the wire electrode at the corner does not occur, or no machining residue occurs, and high-speed machining and high-precision machining can be realized on the workpiece. Also, for example, when the product is a press-cutting die, the fit between the punch and the die or the stripper becomes extremely good, the occurrence of burrs on the punched product is reduced, and the life as a mold is extended, and the durability is improved. We can provide rich things. Therefore, it is possible to manufacture a highly reliable precision product.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an operation relationship between a wire electrode and a workpiece for describing a control method of wire electric discharge machining according to the present invention, and FIG. 2 is a machining condition accompanying movement of the wire electrode in the operation relationship shown in FIG. 3, 4, 5, 6, 7, 8, and 9 are graphs showing change states of corners such as a bent portion and a bent portion in a processed figure of a workpiece. FIG. 10 (A), FIG. 10 (A), FIG.
Figure (B), Figure 10 (C), Figure 10 (D), Figure 10 (E)
And FIG. 10 (F) is a flowchart showing one embodiment of an operation for achieving the wire electric discharge machining control method according to the present invention, and FIG. 11 is a diagram showing a case where a workpiece is subjected to electric discharge machining by a conventional wire electric discharge control method. FIG. 12 is an explanatory diagram showing an example, and FIG. 12 is a schematic diagram showing the relationship between the wire electrode and the workpiece in the case of FIG. 1 ... wire electrode, 2 ... workpiece, 12,13 ... shape error, 14 ... working wire, 15,16 ... die guide member, CP ...
… Corner, L ₁ …… Working distance before this, L ₂ …… Working distance after the corner.

Claims (3)

(57) [Claims] In a method for controlling electric discharge machining of a wire by applying a gap voltage between a wire electrode and a workpiece, a corner of a bent portion or a bent portion exists in a predetermined machining figure. In response to this, the machining conditions are continuously changed stepwise over a plurality of steps at a very small distance before and after the corner at every moving distance of about 0.005 mm to 0.1 mm, and the machining condition is changed during the minute distance before and after the corner. And controlling the electric discharge machining of the workpiece by continuously controlling the wire electric discharge machining without stopping the feed of the wire electrode. 2. The method according to claim 1, wherein said machining conditions are machining speed, gap voltage, discharge time, discharge pause time, and wire electrode tension. . 3. The wire electric discharge machining according to claim 1, wherein the corner is a connection point between a straight line and a straight line, a straight line and a curved line, a curved line and a curved line. Control method.