JP2997342B2 - Oscillating machining control method for Die-sinker EDM - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finishing machine for machining a workpiece by applying a gap voltage between the workpiece and a tool electrode to discharge the workpiece and discharge the workpiece with discharge energy. The present invention relates to a swing machining control method for controlling swing machining that is sometimes performed.

[0002]

2. Description of the Related Art Die-sinker EDM using a Die-sinker EDM
A machining method that uses the electrode wear phenomenon caused by electric discharge. The machining tool is used as an electrode. The tool electrode is brought close to the workpiece in the machining fluid, and a transient arc discharge is repeatedly generated at intervals of several tens μm to several μm. Thus, a predetermined machining shape is machined on the surface of the workpiece by the action of heat and pressure at the time of electric discharge. The metal melted by the heat of the electric discharge, ie, the machining waste, is rapidly cooled by the machining fluid, and the metal of the machining waste becomes sludge by the explosive force and flows out together with the machining fluid.

[0003] Unlike other types of machining, the diesinking EDM using a sculpture electric discharge machine is such that a tool electrode corresponding to a blade used in machining does not come into contact with a workpiece and always keeps a constant interval. Is controlled. That is, in order to prevent a short circuit due to contact between the workpiece and the tool electrode, a servo motor or a hydraulic pressure is used for feeding the tool electrode, and the servo action is repeated so as to always keep an optimum interval.

[0004] Die-sinker EDM using a sink-and-sink electrical discharge machine is one of the indispensable machining methods for metalworking, because it can process tough materials and hard materials that are difficult to machine. On the other hand, die sinking electrical discharge machining is a method in which machining is achieved by transferring the shape and precision of a tool electrode to a workpiece, and the superiority of the production of the tool electrode greatly appears in the machining result.

[0005] In recent years, rocking machining has become possible with the spread of NC electric discharge machines. Oscillation is a process in which a table on which a tool electrode or a workpiece as a tool is mounted is repeatedly finely moved in a horizontal direction, and a relative movement or oscillation is given between the tool electrode and the workpiece. This is a processing method for securing dimensions and improving surface roughness, and is a processing method used in the final finishing step of a mold.

FIGS. 1, 2, and 3 show this swinging process.
This will be described with reference to FIG. FIG. 1 is a schematic view showing an example of a sinking electric discharge machine, FIG. 2 is a processing flowchart showing an embodiment of an operation for achieving a swing machining control method according to the present invention, and FIG. FIG. 4 is a plan view for explaining the movement, and FIG. 4 is a partial cross-sectional view showing a state where the workpiece is oscillated by the sinker electric discharge machine. The workpiece 1 to be machined is set on the workpiece mounting base 2 on the NC table 7 of the die sinking electric discharge machine 10, and is fixed by clamping with the clamp 3. When a circular hole 4 having a diameter D and a depth H is formed in the workpiece 1 by rocking processing, first, a cylindrical tool electrode 5 (diameter) attached to a head body 6 of a die sinking electric discharge machine 10 is used. Rough processing is performed using D ′ <D), and a circular hole 4 slightly smaller than the diameter D and the depth H is formed.
Next, the tool electrode 5 is replaced with the diameter d, and finishing is performed by swinging. Finishing is repeatedly performed by changing the processing conditions in any number of stages. Thereby, the side surface 41 of the circular hole 4 is formed by the side surface 51 of the tool electrode 5 and
The bottom surface 42 of the circular hole 4 is machined by the bottom surface 52, and finally the circular hole 4 having a diameter D and a depth H is finished. In this case, a circular oscillating motion is used as the oscillating motion pattern.

[0007] For example, consider a case where a circular swing shown in FIGS. 3 and 4 is commanded by a program. First, the tool electrode 5
Is moved from the center point O of the circular oscillation to the starting point A of the circular oscillation. For example, if the distance OA is 1 mm, the program instructing the positioning operation is G
17 G00 X1000. Here, G17 is X
Used when Y is commanded together. G00 represents a positioning operation. X represents the amount of movement in the X direction.

Next, a diameter of 2 m around the center point O of the circular oscillation
When the tool electrode 5 is caused to perform a circular oscillation of m, that is, when the center axis 53 of the cylindrical tool electrode 5 moves on a circumference 60 having a diameter of 2 mm, a program for instructing the circular oscillation includes:
G03 X-2000 Y0I-100 J000. Here, G03 indicates that a counterclockwise circular swing is commanded. X is the amount of movement in the X direction from the start point A to the end point C of the swing, Y is the amount of movement in the Y direction from the start point A to the end point C of the swing, I is the X coordinate of the center O of the circle, and J is This is the Y coordinate of the center O of the circle.

[0009]

As described above, the oscillating machining is performed in the finishing process of a die or the like in the diesinking EDM, and the size required by the workpiece is as described above. And to improve surface accuracy, and must be implemented with great care. Therefore, when precise work dimensions are required, it is necessary to interrupt the sinking electric discharge machining from time to time, that is, to make it into a feed hold state, and confirm the finished state of the work by visual observation and dimension measurement.

In FIG. 3, when rocking processing is started from a starting point A and a feed hold state is set at a point B in the middle, the range indicated by the two-dot chain lines 5A and 5B, which is the rocking processing part 43, is not changed. One-dot chain line 5O which is the processing portion 44
It is deeper than the outside of the range indicated by. Therefore, if the tool electrode 5 is then retracted horizontally to the position shown by the dashed line 50 in order to confirm the finished state, the bottom 52 of the tool electrode 5 comes into contact with the unprocessed portion 44, which is one step higher. Become.

In the feed hold state, the energy of the electric discharge machining is cut off, and the servo action does not work.
When the workpiece 1 is small, an excessive clamping force is not applied, so that contact of the tool electrode 5 with the workpiece 1 may cause the workpiece 1 to move. Further, when the tool electrode 5 is small, there is a problem that the tool electrode 5 is bent or broken. Therefore, it is necessary to solve the problem of retracting the electrode in the feed hold state so as not to contact the workpiece.

When the feed hold button is pressed to enter the feed hold state in the middle of the swing of the swing processing shown in FIGS. 3 and 4, the tool electrode 5 is machine-locked and stops at the position B. . However, the NC moves to the end point C of the circular orbit according to the above-mentioned program.
Therefore, when the tool electrode 5 is moved to the center point O of the circular oscillation, the end point D of the movement commanded by the NC and the central point O of the circular oscillation are obtained.
And a gap occurs. For this reason, when the feed hold state is reset and re-machining is started, a machining error is caused by this deviation, which is not suitable for precision machining. Therefore, it is necessary to solve the problem of correcting this shift.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem. Even when the tool electrode in the field hold state is retracted, the workpiece moves or the tool electrode moves with the retraction of the tool electrode. Provided is a method for controlling a swing machining of a die sinking electric discharge machine, which can prevent bending or breakage of a workpiece, and can prevent a machining error from occurring even when reworking is performed. It is.

[0014]

The present invention is configured as follows to achieve the above object. That is,
The present invention relates to a die sinking electric discharge machine for applying a voltage between a workpiece and a tool electrode to discharge the workpiece, and processing the workpiece with discharge energy. And then simultaneously retreating the swing axis and a servo axis orthogonal to the swing axis in the counter-machining direction, and then controlling the coordinate system setting of the swing axis. .

Here, the swing axis refers to the X axis and the Y axis, and the servo axis refers to the Z axis. The non-machining direction refers to a direction other than the machining direction. For example, the anti-machining direction with respect to the oscillating axis is a direction other than the counterclockwise direction on the oscillating trajectory.
Including the direction toward. The direction opposite to the machining with respect to the servo axis is a direction away from the workpiece in the Z-axis direction.

[0016]

Since the present invention is constructed as described above, it operates as follows. That is, when the feed hold state is set during the swing machining, the tool electrode stops in the middle of the circular swing orbit. Therefore, the tool electrode is retracted in the direction opposite to the swing axis in the machining direction, for example, in the direction of the center point O of the circular oscillation. At this time, the anti-machining direction, that is, Z
The tool electrode is retracted axially away from the workpiece. Thereby, even if the tool electrode is retracted,
The tool electrode does not come into contact with the unprocessed part of the workpiece.

Further, when the tool electrode stopped in the course of the circular oscillating path is moved to the central point O of the circular oscillation, the center point O of the circular oscillation deviates from the end point of the movement commanded by the NC. However, this deviation can be eliminated by setting and correcting the coordinate system of the swing axis. Therefore, there is no machining error when the feed hold state is reset and re-machining is started.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a swing machining control method for a die sinking electric discharge machine according to the present invention will be described below with reference to the drawings. FIG. 2 is a processing flow chart showing one embodiment of the swing machining control method of the die sinking electric discharge machine according to the present invention.

The operation of the die sinking electric discharge machine 10 is controlled by an NC unit. When the start button in the die sinking electric discharge machine 10 is pressed, the main control unit of the NC device reads the program registered in the memory unit and instructs a machining power supply unit to machining conditions, instructs a servo unit to machine position, Servo movement is performed on the tool electrode 5 moving device and the NC table 7 attached to the head body 6 of the die sinking electric discharge machine 10, and a gap voltage is applied between the tool electrode 5 and the workpiece 1 by applying a voltage between them. And discharge machining is performed on the workpiece 1 with the discharge energy.

Referring to FIGS. 2, 3 and 4, a method for controlling the swing machining of the die sinking electric discharge machine according to the present invention will be described.
The following description focuses on the movement of the axis, the Y axis, and the Z axis. When the start button is pressed, the Z-axis servo starts first (step 1).
Along with 1), the X-axis servo and the Y-axis servo are activated (step 12). The interval between the workpiece 1 and the tool electrode 5 is controlled to be always maintained at a constant interval and to perform servo movement,
As long as the field hold button is not turned on (step 13), the workpiece 1 is subjected to electric discharge machining. Processing is performed one after another until a series of processing is completed according to the registered program (step 14).

If it is necessary to check the finished state of the workpiece 1 visually and by dimensional measurement during the electric discharge machining of the workpiece 1, the feed hold button is pressed (step 13). When the feed hold button is pressed, the X-axis, the Y-axis, and the Z-axis are machine-locked, and the swing processing is stopped (step 15). Since the position where the feed hold state is set is the position of the tool electrode 5 when the feed hold button is pressed, it is an arbitrary position B on the circular swing locus. On the other hand, the NC moves to the end point C of the circular trajectory designated by the program, that is, the feed hold confirmation position C (step 16).

In the feed hold state, the tool electrode 5 must then be retracted to measure the dimensions of the work surface of the workpiece 1. Therefore, the tool electrode 5 is, for example, 0.1 m
In this state, the tool electrode 5 is moved in the X-axis and Y-axis directions from the position B stopped by the machine lock to the center point O of the circular oscillation (step 17). With the retreat of the tool electrode 5, the position of the NC moves from the point C to the point D,
Since the actual center axis position of the tool electrode 5, that is, the center point O of the circular oscillation occurs, the position X of the NC is corrected to match the center point O of the circular oscillation of the tool electrode 5. A coordinate system is set for the axis and the Y axis (step 18).

When the coordinate system setting is completed, the NC device is stopped (step 19). When the NC device is restarted again, the process returns to step 1, and the electric discharge machining is performed again according to the above-described process.

[0024]

The swing machining control method according to the present invention has the following effects because it is configured as described above. First, in order to check the finished state of the workpiece visually and by dimensional measurement, even if the tool electrode is retracted with the wire electric discharge machine in the feed hold state, the tool electrode contacts the workpiece as before. Is gone. Therefore, it is possible to prevent the workpiece from moving or the tool electrode from being bent or damaged due to the retreat of the tool electrode.

Further, since the deviation between the center point O of the circular oscillation and the end point of the movement commanded by the NC can be eliminated, the machining error when the feed hold state is reset and re-machining is started is reduced. This has the effect of improving machining accuracy on the workpiece.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a die sinking electric discharge machine capable of achieving a swing machining control method according to the present invention.

FIG. 2 is a processing flowchart of a swing machining control method of the die sinking electric discharge machine according to the present invention.

FIG. 3 is a partial cross-sectional view showing a state in which a workpiece is rocked by a sinker electric discharge machine.

FIG. 4 is a plan view of FIG. 3 and is a schematic view illustrating circular oscillation in the swing machining.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Workpiece 2 Workpiece mount 4 Circular hole 5 Tool electrode 10 Die-sinker EDM

────────────────────────────────────────────────── ─── Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B23H 1/00-1/02 B23H ⁷ /14-7/32

Claims (1)

(57) [Claims] 1. A die-sinking electric discharge machine for applying a gap voltage between a workpiece and a tool electrode to discharge the workpiece, and processing the workpiece with discharge energy, in a feed hold state during swing machining of the workpiece. When the oscillating axis and the servo axis perpendicular to the oscillating axis are simultaneously retracted in the anti-machining direction,
A swing machining control method, comprising controlling the coordinate system setting of the swing axis.