JPH0739059B2 - Correction processing method in electric discharge machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for directly measuring the shape of a processed portion of a workpiece in processing and performing correction processing based on the measurement result. Such a method is preferably applied to electrical discharge machining or the like in which the shape of the tool is directly transferred to the shape of the machined portion.

[Prior Art and its Problems] Electric discharge machining is generally used as one of precision machining methods. Electric discharge machining uses a tool as an electrode to generate an arc discharge in a minute gap between the workpiece and the workpiece, thereby removing a small amount of the workpiece surface and machining the workpiece into a shape corresponding to the shape of the tool. To do.

EDM makes it possible to machine tough materials and high-hardness materials that are difficult to machine into precise shapes, and the surface can be made relatively fine. Since the surface can also be machined, electrical discharge machining is used, for example, in the manufacture of dies for pressing.

A conventional example of an electric discharge machine used for such electric discharge machining is shown in FIG.

In the figure, 102 is an X-direction slide table, and 104
Is a Y-direction slide table provided on the X-direction slide table 102.
A machining liquid storage tank 106 is fixed on the upper part of 4. 108 is a work table provided in the tank 106, and the work table 108
The work 110 is fixed on the top. During the processing, the tank 106 stores a processing liquid such as water or oil. 1
12 is a column, 114 is a working head, 116 is an insulating plate, 118 is a chuck, 120 is a rotary head, 122 is an electrode holder, and 124 is an electrode or tool.

The rotary head 120 can rotate in the Z direction with respect to the chuck 118. That is, the rotary head 120 is fixedly provided with a horizontally projecting portion 120a, while the chuck
Rotation adjusting screws 118a and 118b, which are in contact with the protrusion 120a from both sides with respect to the rotation direction around the Z direction, are attached to the 118. Therefore, the rotary head 120 can be rotated with respect to the chuck 118 by operating the two adjusting screws 118a and 118b.

In addition, the electrode holder 122 is attached to the electrode 1 from the X and Y directions.
Adjustment screws 122a and 122b that are brought into contact with 24 are provided, and the tilt of the electrode 124 in the Z direction can be corrected by operating the adjustment screws 122a and 122b. That is, by operating the adjusting screw 122a, the electrode 124
Rotate around the Y direction by an appropriate angle,
By manipulating 122b, the electrode 124 is rotated around the X direction by an appropriate angle.

During electric discharge machining, the electrode 124 is moved downward with respect to the column 112 along the Z direction, and electric discharge is started at a position where the gap between the electrode 124 and the work 110 is very small. After that,
Discharge is performed while gradually moving the electrode 124 downward, stopping the discharge at a predetermined position, and moving the electrode 124 upward. As a result, the processed surface corresponding to the shapes of the lower surface and the side surface of the electrode 124 is formed on the work 110.

However, in the conventional electric discharge machine as described above, since the posture of the electrode 124 mounted on the electrode holder 122 is not always accurate, the electrode surface can be moved vertically after mounting the electrode 124. Alternatively, a dial gauge is brought into contact with the reference surfaces 124a and 124b formed on the side surfaces of the electrode to measure the tilt of the electrode, and the adjusting screw 12 is adjusted based on the measurement result.
2a and 122b are operated to rotate the electrode 124 around the X direction and around the Y direction, and while the dial gauge supported on the work table is brought into contact with the electrode surface or the reference surface, the work table. Is moved in the X direction or the Y direction to measure the rotation of the electrode around the Z direction, and the adjusting screws 118a and 118b are operated based on the measurement result to rotate the electrode 124 around the Z direction. The adjustment of the desired electrode posture is performed by.

On the other hand, in electrical discharge machining, one electrode per workpiece
Only one shape can be processed. Therefore, a plurality of electrodes are required when performing complicated machining, and the electrodes are exchanged in the electric discharge machine. Also, in the case of electrical discharge machining, in order to maintain good finishing accuracy even when machining the same shape, the electrode for rough machining may be first machined and then the electrode for finish machining may be machined. The electrodes are replaced in the machine.

Depending on the type of work, 100 or more electrodes may be used by the end of processing.

Therefore, in the conventional electric discharge machining, the posture of the electrode is manually measured as described above every time the electrode is mounted on the electric discharge machine, and the posture of the electrode can be adjusted within a desired allowable range based on the measurement. Has been done. For this reason, the setup process time required for electrical discharge machining is long, and improvement in work efficiency cannot be expected.

For this reason, attempts have been made to automatically replace the electrodes by using the automatic electrode changing device to reduce the time and manual work of the setup process, but there is a replacement error in the current automatic electrode changing device. Conventionally, the feed size of the tool during machining is often set uniformly by the tool and the machining section, so that sufficient machining accuracy cannot be obtained if machining is performed in that position.

Further, in electric discharge machining, a machining portion having a shape corresponding to the electrode shape is formed as described above, but in reality, the machining time elapses due to the heat generated by the motor or the like in the machining machine or the heat generated by electric discharge. At the same time, the relative position between the workpiece and the electrode is displaced, which causes the shape of the processed portion (in the present invention, the position of the processed portion with respect to the point or surface serving as the reference of the workpiece is also included). Changes. That is,
Even if the mounting posture of the electrode with respect to the processing machine does not change, the shape of the processed portion formed is not always the same. When high processing accuracy is required, the shape of the machined part is measured after processing to some extent to correct such minute shape changes, and based on the measurement results, a precise shape is obtained to finally obtain the desired shape. Correction processing for trace removal by feeding may be performed.

Therefore, for the shape measurement of the processing part for such correction processing, a measuring ball is attached to the electrode holder instead of the conventional electrode,
This is done by bringing the measuring sphere into contact with the processed part.

However, in such a conventional measuring method, it is necessary to repeat the attachment and detachment of the electrode and the attachment and detachment of the measurement sphere each time the measurement is performed, and the setup is complicated, and the above-mentioned attachment and detachment error occurs every time the electrode is attached. Therefore, if the machining is carried out as it is, it is not possible to expect high-precision machining, and for the high-precision machining, it is necessary to carry out the posture control as described above for each electrode mounting.

For this reason, conventionally, in electrical discharge machining, it was practically impossible to automatically perform mass production machining with high accuracy.

The above-described problems may exist not only in electric discharge machining but also in general machining machines for exchanging tools.

[Means for Solving Problems] According to the present invention, as a solution to the problems of the prior art as described above, a discharge electrode having a shape corresponding to a planned processing shape of a workpiece, and the discharge electrode First to support
Supporting means, a second supporting means for supporting the workpiece, a first measuring means attached to the first supporting means, and a second measuring means attached to the second supporting means. And a moving means for moving the first supporting means and the second supporting means relative to each other. Information about a shape and its position is stored, relative movement of the first supporting means by the moving means with respect to the second supporting means is measured, and based on this, the first relative to the second measuring means. The position of the measuring means is determined, and the second supporting means is moved with respect to the first supporting means to bring the second measuring means into contact with a plurality of positions on the surface of the discharge electrode. In the case of the first supporting means The position of the discharge electrode is measured based on the moving direction and distance of the second supporting means to store the information on the position of the discharge electrode, and the surface of the discharge electrode with which the second measuring means is brought into contact. Information of a plurality of positions of the first support means is moved relative to the second support means to bring the first measuring means into contact with the workpiece, and the second The position of the workpiece is measured based on the moving direction and the distance of the first supporting unit with respect to the supporting unit, and the information is stored, and the stored information regarding the position of the discharge electrode and the workpiece are stored. From the information on the planned machining shape of the object and its position, information on the direction and distance to the position of the planned machining shape of the workpiece with respect to the current position of the discharge electrode is obtained, and a machining target is set based on the information. The first supporting means is the first Two
The workpiece is processed by the discharge electrode by moving it with respect to the supporting means, and the stored information of a plurality of positions on the surface of the discharge electrode and information on the planned machining shape of the workpiece and the position thereof. Based on the information of a plurality of positions of the planned machining shape of the workpiece corresponding to a plurality of positions on the surface of the discharge electrode, based on the information, the first measuring means to schedule the workpiece By moving the first supporting means with respect to the second supporting means with the plurality of positions of the processed shape as a target, the plurality of positions of the processed portion of the processed object are brought into contact with the plurality of positions. The position of the processing portion is measured based on the moving direction and distance of the first supporting means with respect to the second supporting means at that time, the information is stored, and the stored processing of the workpiece is performed. For the shape and position of the later processing part Based on the information and the information on the planned machining shape of the workpiece and the position thereof, the deviation between the position of the machining part after machining of the workpiece and the position of the planned machining shape of the workpiece is calculated, In the subsequent machining, there is provided a correction machining method in an electric discharge machine, characterized in that the machining target is corrected in a direction of correcting the deviation and then the correction machining is performed.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an electric discharge machine to which the correction machining method of the present invention is applied. In this figure, the same members as those in FIG. 12 are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, 42 is an attitude control device. 44 is an insulating plate, 46 is an electrode mounting face plate, 48 is a pull-stat chuck, and 50 is an electrode holder. Reference numeral 52 is a touch sensor.

The attitude control device 42 can independently rotate the electrode 124 side (that is, the lower side) around the Y direction, around the Y direction, and around the Z direction, and this rotation can be performed by an appropriate drive circuit ( Will be described later).

Further, in FIG. 1, the column 112 has support arms 2, 3, 4, 5, and 4.
Hydraulic cylinders 6 and 7 supported by are attached.
The piston rods 8 and 9 of the hydraulic cylinders 6 and 7 face the Z direction. The upper ends of the rods 12, 13 are connected to the upper ends of the piston rods 8, 9 via connecting members 10, 11. The rod-shaped body 1
2 and 13 are oriented in the Z direction, and can be reciprocated in the Z direction by being guided by guide members 14, 15, 16 and 17 attached to the supporting arms 2, 3, 4, and 5. Touch sensors 30, 31 and measuring elements 18, 19 are formed at the lower ends of the rod-shaped bodies 12, 13. In addition, the rod-shaped members 12, 13 are provided on the guide members 14, 15, 16, 17.
Means 20,21,22,23 for locking the are provided.

Therefore, by operating the hydraulic cylinders 6 and 7, the tracing stylus 18 and 19 can be positioned at a desired height in the Z direction.

It is not always necessary to provide the two measuring means attached to the column 112 as described above.
Depending on the range of 0, only one stroke may be provided if the stroke of the slide table is sufficiently secured. Further, the measuring means may be attached to the processing head.

FIG. 2 is a block diagram showing the configuration of the control system of the electric discharge machine shown in FIG.

In the figure, the X-direction slide table 102, the Y-direction slide table 104, and the electrode Z-direction slide means 54 of the main body of the electric discharge machine are connected to a drive circuit 56, which is instructed by the CPU 60 in the X-direction and Y-direction, respectively. And the Z direction. Furthermore, the X direction, the Y direction, and the Z
The position counter value of the drive circuit 56 when the touch sensor 52 contacts the shape surface of the electrode 124 in X, Y, Z
It can be stored in the CPU 60 as the coordinate value of.

The drive circuit 56 is also connected to hydraulic cylinders 6 and 7 for driving the tracing stylus, and the tracing circuits 18 and 19 provided at the lower ends of the rod-shaped bodies 12 and 13 are moved in the Z direction by the driving circuit 56. . Further, the amount of movement of the tracing stylus 18, 19 in the Z direction is input from the drive circuit 56 to the CPU 60, whereby the coordinates of the tracing stylus 18, 19 at a desired time can be stored in the CPU 60. .

An electrode exchange device 66 is also connected to the CPU 60.

A machining method using the electric discharge machine configured as described above will be described for each of the following items.

(I) Coordinate system (ii) Preparation step (iii) Description of processing method (iii-1) Electrode attitude control step (iii-2) Processing method (i) Description of coordinate system Basic coordinate system Co _{Attached to} machining head As shown in FIG. 13, the measuring sphere 201 and the apex of the touch sensor 52 are brought into contact with each other, and the coordinate system whose origin is the position of the slide table 102 in the X direction, the slide table 104 in the Y direction and the slide means 54 in the Z direction at this time is C. _o .

At this origin position, the X, Y, and Z axis feed counters in the drive circuit 56 are cleared, and the movement amount of the machine is counted with this point as a reference.

The process relating to the posture correction of the electrode by the processing machine of the present invention and the process relating to the processing are performed in this coordinate system C _o .

Measuring coordinate system C _{m In the} measuring coordinate system C _m , the moving direction of the probe parallel to the Z axis is the Z ′ axis, the moving direction of the X direction slide table 102 is the X axis,
Y direction XY with the moving direction of slide table 104 as the Y axis
It is composed of Z'axis, and the contact point is brought into contact with the apex of the touch sensor. This position is set as the origin of the measurement coordinate system C _m , and the moving amount counter of the contact point is cleared to be the origin of Z'axis.

Also, stores from the origin of the C _o the movement and direction of the X-direction slide table 102 and the Y-direction slide table 104 between the origin of the C _m to the CPU as an offset value. Then X axis, Y
Clear the axis counter and measure the X-axis and Y-axis in the measurement coordinate system C _m .
Use as the origin of the axis.

Here, when counting and displaying the position of machine movement from one coordinate system to the other coordinate system, position counting and display conversion are performed based on this offset value.

(Ii) Preparation Step The electric discharge machining apparatus used in the machining method of the present invention is to machine a work into a predetermined shape while sequentially exchanging a plurality of machining electrodes. Further, there is provided a posture control device that automatically measures the tilt of the electrodes when these electrodes are attached to the processing head and then corrects the posture. In order to automatically measure the tilt of the electrode, it is necessary to perform a preparatory work such as selecting a measurement point of each electrode used for processing and setting a measurement start point for measuring the electrode. Hereinafter, selection of measurement points and setting of measurement start points will be described with reference to FIG.

(Ii-1) Selection of measurement point Since the electrode moves parallel to the workpiece during machining, when measuring the attitude of the electrode, the rotation angle around the X direction from the reference attitude, that is, Y The rotation angle around the Y direction, that is, the X rotation, and the rotation angle around the Z direction, that is, the Z rotation may be obtained.

(A) Case of Square Electrode FIG. 4 (a) shows a square electrode. In order to obtain the X-taole, the coordinates of a plurality of points on the electrode surface intersecting the Z-X plane are measured. The measurement point is, for example, 2 from the side surface of the electrode.
Select the location (x ₁ , x ₂ ) or 2 locations (x ₃ , x ₄ ) from the lower surface of the electrode. Similarly, in order to obtain the Y-taole, the coordinates of a plurality of points on the electrode surface intersecting the YZ plane are measured. As the measurement points, for example, two locations (y ₁ , y ₂ ) from the side surface of the electrode or two locations (y ₃ , y ₄ ) from the lower surface of the electrode are selected.

Further, in order to obtain the Z rotation, the coordinates of a plurality of points on the electrode surface intersecting the XY plane are measured. For example, two points (z ₁ , z ₂ ) on the side surface of the electrode) or ((z ₃ , z ₄ )) are selected as the measurement points.

(B) In case of round electrode FIG. 4 (b) shows a round electrode. Z for round electrode
Since it is not necessary to consider the rotation, X-taole and Y-taole may be measured in the same manner as in the case of the rectangular electrode.

Further, in the case of a circular electrode, as shown in FIG. 4 (c), two sets of different Z coordinates on a plane parallel to the XZ plane and a plane parallel to the YZ plane are measured. Points w ₁ to w ₄ and w ₅
Select ~ w ₈ and. Then, calculates their coordinates center point w ₁ from the coordinates of the measurement point w ₁ to w _4, further calculates their center points w ₂ coordinates from the coordinates of the measurement points w ₅ to w _8, w ₁ , w ₂ is calculated by calculating the direction of the line that connects
You can ask for Taole.

(Ii-2) Setting of measurement start point The measurement start point means a feed start point for bringing the touch sensor into contact with each measurement point selected in (ii-1). A measurement start point is set for each measurement point.

(A) In the case of a square electrode In FIG. 4 (a), when measuring X-taole, a position x ₁ is appropriately separated from the measurement points x ₁ and x _{2 in the} X direction. The touch sensor 52 is positioned at ′, x ₂ ′, and these are used as the starting points of coordinate measurement of the measurement point. Further, with respect to the measurement points x ₃ and x ₄ , the touch sensor 52 is placed at positions x ₃ ′ and x ₄ ′ which are separated from the measurement points by an appropriate distance in the Z direction.
Are set, and these are used as the starting points of the coordinate measurement of the measurement point.

These starting points are set by teaching in advance according to the type of electrode. That is, the measurement start point for the electrode is stored as data in the CPU 60 before the electrode attitude measurement for actual machining is started, and the X direction slide table 102, the Y direction slide table 104 and the Z direction slide are manually operated. Operate the means 54 to position the touch sensor 52 at the starting point,
The relative position of the touch sensor 52 and the electrode at that time is stored in the CPU 60 as a coordinate value.

(B) Round electrode In the case of a round electrode as shown in Fig. 4 (b),
Instead of setting the measurement start point by manual teaching for all measurement points x _{1 to} x ₄ and y _{1 to} y ₄ ,
Manually teach only the measurement start points for x ₁ , x ₂ and x _3, and set the measurement start points for the other measurement points x ₄ , y _{1 to} y ₄ based on the axial symmetry of the electrodes. It may be set automatically from the start point coordinates. Such automatic setting can be easily performed by incorporating a program in the CPU 60 in advance.

Further, in the case of the measurement as shown in FIG. 4 (c), for example, by manually teaching only the measurement start points for the measurement points w ₁ , w ₂ , w ₅ , other measurement points w ₃ , w ₄ , w _{6 to} w ₈ may be automatically set in the same manner as in the case of FIG. 4 (b).

When setting the measurement start point, instead of performing the above-mentioned teaching, directly use the CP
It may be entered in the U 60 and stored.

The measurement of the X-taole has been described above, but the same applies to the measurement of the Y-taole and the Z rotation.

After setting the measurement start point and positioning the touch sensor 52 at the measurement start point in the electrode coordinate measurement as described above, the touch sensor 52 may be moved in a predetermined direction in a direction in which the absolute value of the coordinate becomes smaller. . Further, the movement of the touch sensor between the measurement points is performed so as not to collide with the electrode 124 along the X, Y or Z direction, for example.

(Iii) Processing Method FIG. 3 shows a flow of a processing method using the apparatus of the present invention. The processing method will be described based on FIG.

First, the electrode exchange device for the electrode holder 50 of the electric discharge machine
Electrodes are exchanged by 66 (step 3-1). This electrode replacement will be replaced with a new electrode when the electrode used in the previous machining is mounted on the electrode holder 50 of the electric discharge machine, and the electrode is not mounted on the pull-stat chuck. In this case, only new attachment of new electrodes is required.

Thus, after the new electrode is mounted on the electric discharge machine, control is performed to correct the posture of the electrode (step 3-2). In this electrode attitude control, after measuring the attitude of the attached electrode, it is determined whether or not the attitude is within a desired allowable range, and if the attitude is not within the desired range, the electrode attitude is corrected. The posture is measured, and the posture is measured within a desired accuracy by repeating the measurement.

Thus, after the newly mounted electrode has a desired posture, the electric discharge machine is operated to move the electrode to bring it closer to the work, and electric discharge machining is performed (step 3-3). In this electric discharge machining, the final target shape is not machined at once, but after machining to some extent, the shape of the machined portion is measured by the measuring means, and the machining target is corrected based on the measurement result before machining. If necessary, this correction processing is repeated to obtain a processed portion with desired accuracy.

With the above, accurate electrical discharge machining for the electrode is completed. Then, in order to perform accurate electric discharge machining with another electrode, the above steps 3-1 to 3-3 may be repeated.

Next, details of the electrode attitude control step 3-2 will be described.

(Iii-1) Electrode attitude control step The electrode attitude control step includes: -a measurement step of measuring the attitude of the electrode; -an attitude amount calculation step of calculating the amount of tare from the difference between the measured value and the correct attitude; The process of comparing with the reference value to compare whether it is within the allowable value, ・ The attitude correction process of correcting the electrode attitude to the correct attitude when the tilt of the electrode is outside the allowable value. It will be processed automatically.

A flow sheet of the attitude control process as described above is shown in FIG.

That is, first, the touch sensor 52 is moved to the first measurement start point, and then the coordinate measurement of the first measurement point is performed. Similarly, the coordinate measurement of the second and subsequent measurement points is performed, and the X-direction tilt is performed. Then, the coordinate measurement for the Y direction and the coordinate measurement for the Z rotation are similarly completed (step 5-1).

A posture amount calculation is performed based on the coordinates thus measured (step 5-2).

Next, the posture state quantity obtained by the calculation is compared with the correct posture state quantity stored in advance in the CPU 60 as a reference (step 5-3). If the difference is within the allowable value, Then proceeds to the processing step.

On the other hand, if it is outside the allowable value, the attitude control device 42 is driven to rotate the electrode 124 by an appropriate angle around the X direction, the Y direction and / or the Z direction (step 5-
4) and then return to step 5-2.

(Iii-2) Processing Step Next, details of the processing step 3-3 corresponding to the correction processing method of the present invention will be described.

Before the actual machining, the positional relationship between the electrode and the work is calculated and the feed dimension of the electrode is calculated. FIG. 6 (a),
(8b) is a diagram for explaining a method of calculating the electrode feed dimension.

In the attitude control step 3-2, the result of the electrode coordinate measurement is used to calculate the electrode feed dimension. That is, when the attitude amount calculation is performed based on the measured value after the electrode coordinate measurement and it is determined to be within the allowable range in comparison with the reference value, the measured value represents the coordinate of the electrode. Therefore, the feed dimension can be calculated from this coordinate and the position coordinate of the work 110 fixed on the workbench 108.

In FIG. 6A, a specific example of calculating the feed dimension for the tapered electrode 124 will be described.

First, the angle θ is calculated from the difference between the X coordinates and the Z coordinate of the measurement points x ₁ and x ₂ . Then, the Z coordinate of the point P is calculated from the angle θ and the Z coordinate of the measurement point x _{2 and} the Z coordinate of the measurement point x ₃ .
The Y coordinate of the point P is the same as the Y coordinate of the measurement points x ₁ , x ₂ , x ₃ ,
The Z coordinate of the point P is the same as the Z coordinate of the measurement point x ₃ . Thereby, the coordinates of the point P are obtained.

On the other hand, the coordinates of the point Q of the workpiece 110 in advance in the touch sensor 52 and reference coordinate system C _o (i.e. worktable workpiece 110 10
Measure (when fixed at 8). For this actual measurement, for example, a measuring sphere is attached to the electrode holder 50, the measuring sphere is attached, and the measuring sphere is brought into contact with the point Q of the work 110, so that the X-direction slide table 102, the Y-direction slide table 104, and the Z-direction slide table 104 Driving the direction slide means 54, the work 110
The coordinates of the point Q are obtained. Note that the coordinates of the point Q, may be measured by contacting the direct measurement ball point Q in the manner described above, but the point q ₁ measurement sphere as shown in FIG. 6 (b), q ₂ , q ₃ may be brought into contact with each other to measure the coordinates of these points, and the coordinates may be calculated from the coordinates.

Further, R is a point on the final target processed surface on which the work is to be formed, corresponding to the point P of the electrode 124. The relationship between the point Q and the point R is set by design dimensions.

Therefore, the coordinates of the point Q are obtained from the coordinates of the point P and the relative positional relationship between the touch sensor and the point Q. Based on this, the coordinates of the point R are obtained from the relative positional relationship between the points Q and R, q.

From the above, the feed dimensions in the X, Y, and Z directions for the machining feed from the point P to the point R are calculated. The CPU 60 calculates the feed dimension for this machining.

Thus, the electrodes are moved and the electric discharge machining is executed after the calculation of the machining feed dimension is completed.

Machining is not performed all at once, but the discharge is temporarily stopped midway, the shape of the machined portion is measured, and based on the result, the relative positional relationship between the electrode 124 and the workpiece 110 is corrected, and then further processed. Perform processing.

FIG. 7 is a diagram for explaining a method of measuring the shape of such a processed portion.

After the discharge is stopped, the X-direction slide table and the Y-direction slide table of the electric discharge machine are driven and the hydraulic cylinder 6 is operated without removing the electrode 124, thereby moving the tracing stylus 18 and processing part of the work 110. The tracing stylus 18 is sequentially brought into contact with the points a _{1 to} a ₆ on the surface, and the coordinates (the Y coordinate is constant) of these points are obtained. The coordinates of the points M and N are calculated from the X and Z coordinates of each point thus obtained.

On the other hand, the relative positions of the points M'and N'on the target final machined surface corresponding to the points M and N of the machined part with respect to the point Q'are determined by the design size as described above. Therefore, the point M '
The coordinates of N'and N'can be calculated from the coordinates of the point Q'and the design size.

Therefore, the difference ΔM between the X coordinates between the points M and M ′ and the difference ΔN between the X coordinates between the points N and N ′ are obtained, and the difference between these two differences Δ = ΔM−ΔN is calculated from the current machining surface and the target. It is possible to detect the magnitude (Δ / 2) of the center deviation from the final processed surface and the direction. When the center deviation is large and (Δ / 2) exceeds the allowable value, the amount is stored in the CPU 60.

Although the plane parallel to the XZ plane has been described above, the shape of the machined portion is similarly measured for the plane parallel to the YZ plane.

Next, the hydraulic cylinder 6 is operated to move the tracing stylus 18 upward in the Z direction. Then, further processing is performed using the electrode 124 that is still attached to the electrode holder 50. During this machining, if the current center deviation of the machined surface of the machined part from the target machined surface exceeds the allowable value in the above-mentioned shape measurement, the target value is corrected so as to eliminate the center deviation. . The correction of the target value can be performed, for example, by correcting the feed dimensions in the X and Y directions set in the feed dimension calculation, and thus a new machining target is set.

Incidentally, FIG. 7 shows a case where a tapered electrode is used to perform processing by swinging the electrode around the Z direction. In this case, the center deviation is corrected by the swing center axis of the electrode. The target can be corrected by moving (Δ / 2) in the X direction and moving in the Y direction by an amount calculated in the same manner.

In addition, in the processing part shape measurement for this correction processing,
The measurement start point for each measurement point can be set in association with the measurement start point set in the electrode coordinate measurement.

Next, a method of setting the measurement start point for measuring the shape of the processed portion will be described.

In FIG. 8, x ₁ ″ to x ₆ ″ are measurement start points for measuring the shape of the processed part of the work 110, and the probe is moved in the X direction from this measurement start point to the measurement points. However, since the shape of the processed portion is not formed on the workpiece before processing, the measurement start point cannot be set by teaching.

Therefore, these measurement starting points x ₁ ″ to x ₆ ″ are set based on the measurement results obtained by the electrode coordinate measurement in step 5-1.

That is, for the electrode measurement points x _{1 to} x ₆ , the electrode measurement start point x ₁ ′ to
A point separated by a predetermined distance in the opposite direction from x ₆ ′ is set as x ₁ ″ to x ₆ ″.

As a result, the measurement starting point for measuring the shape of the processed portion to which the electrode shape is transferred is set. In this case, these measurement starting points x ₁ ″ to x ₆ ″ are set as a relative positional relationship with a reference point of the electrode, for example, point P. As a result, when the coordinate value of the point R corresponding to the point P is set, the coordinates of the measurement start point for measuring the shape of the processed portion are relatively determined. In the electrode coordinate measurement, the touch sensor 52 measures the measurement starting point x ₁ ′ to x ₆ ′.
Moves in a direction in which the absolute value of the coordinate decreases (that is, toward the electrode 124), but in the measurement of the shape of the processed portion, the probe 18 moves in the opposite direction to the electrode coordinate measurement.

Since the shape of the machined part is measured before the final target machined surface is formed, the measurement starting point x ₁ ″ ~ x ₆ ″ has a reasonable margin (that is, it should be inside the measurement point of the work part). To).

By repeating the above processing and shape measurement a predetermined number of times, a more accurate processed surface can be obtained.

FIG. 9 shows a detailed flow sheet of the overall configuration of the embodiment including the correction processing method of the present invention as described above. Here, the final machined surface is obtained after the number of times of repeated machining (including the initial machining) m times.

FIG. 10 shows a flow sheet of another embodiment of the above processing system.

In the present embodiment, when the posture amount obtained in the posture amount calculation step for the same electrode is not allowed, the number of times of ace is n or more, and the electrode is replaced without further posture correction. Move to the process.

As a result, it is possible to shift to processing by the next electrode without attempting long-time posture control for the electrode for which posture control cannot be performed satisfactorily for some reason.

Further, in the present embodiment, the related electrode pass command is issued when shifting to the electrode replacement process due to the posture correction failure.

The related electrode path will be described below.

FIG. 11 shows a plurality of works 110 and 111 fixed on the work 108.
FIG. The work 110 has processing parts A, B, C, D and E,
The work 111 has processing portions E and F. These processing parts A to
F is processed by the electrodes 124a to 124f, respectively. electrode
The processing of the processed portion B by 124b is performed after the processing of the processed portion A by the electrode 124a, and the processing of the processed portion C by the electrode 124c is performed after the processing of the processed portion B by the electrode 124b.

Therefore, if the processing portion A is not processed due to a defective posture correction of the electrode 124a, the processing portions B and C are then processed.
Can not be processed. In such a case, it is desirable not to mount the electrodes 124b and 124c for machining the machining parts B and C on the electric discharge machine.

Therefore, when the electrodes related to the related processed parts belonging to the same block are passed, the electrodes related to the processed parts belonging to the same block are also passed thereafter. Such a related electrode pass can be performed by the software of the CPU 60 by attaching a code to each electrode. When the workpieces 110 and 111 as shown in FIG. 11 are machined, for example, the following codes are attached to each electrode, and the machining system is controlled by these codes. Electrode code 124a 110-A-1 124b 110-A-2 124c 110-A-3 124d 110-D-1 124e 110-E-1 124e 111-E-1 124f 111-F-1 The first number of indicates the type of work to be processed by the electrode, the next number indicates the type of processed block, and the last number indicates the processing order of the processed parts in the processed block. As the electrode 124e is provided with two cords, the electrode may have two or more cords when the same electrode is processed at two or more places.

Therefore, when, for example, the electrode 124a is passed due to poor posture correction, the electrodes 124b and 124c having the same machining block type code A are commanded and stored so as to pass thereafter. Then, in the electrode replacement step 3-1, it is confirmed whether or not the electrode to be newly mounted is a pass command before the electrode replacement is performed, and immediately if a pass command is issued, it is immediately confirmed. The electrode moves to the next processing sequence.

In the above embodiments, the coordinate measurement has been described by ignoring the fact that the probe and the touch sensor have a size. In reality, since the probe and the touch sensor have a size,
In the coordinate measurement, it is necessary to make a correction based on this point, but such a correction calculation can be easily performed by a conventional method.

Although the electric discharge machining has been described in the above embodiments, the modified machining method of the present invention can be similarly applied to general machining for exchanging tools or workpieces other than electric discharge machining.

[Advantages of the Invention] According to the modified machining method of the present invention, since the machining portion shape is measured without removing the tool from the machining machine, the positional deviation between the tool and the machining portion of the workpiece can be detected extremely accurately. Based on this, it is possible to improve the correction processing accuracy.

Further, according to the modified machining method of the present invention, it is possible to configure a machining system in which tool exchange is automatically performed to perform plural types of machining unmanned, continuously and extremely accurately.

[Brief description of drawings]

FIG. 1 is a block diagram of an electric discharge machine. FIG. 2 is a block diagram of a control system of the electric discharge machine. FIG. 3 is a flow sheet of a processing system to which the correction processing method of the present invention is applied. 4 (a), (b) and (c) are partial perspective views of the electrode. FIG. 5 is a flow sheet of the attitude control process. FIGS. 6 (a) and 6 (b) are views for explaining the machining feed dimension calculation. FIG. 7 is a diagram for explaining the processing portion shape measurement. FIG. 8 is a diagram showing a method of setting a measurement start point in measuring the shape of a processed portion. 9 and 10 are flow sheets of a processing system including the method for measuring the shape of a processed portion according to the present invention. FIG. 11 is a diagram showing a processing part of the work. FIG. 12 is a schematic view of a conventional electric discharge machine. FIG. 13 is a diagram showing a state when the coordinate system is set. 18, 19: Stylus 42: Posture control measurement 50: Electrode holder 52: Touch sensor 102: X-direction slide table 104: Y-direction slide table 108: Work table 110, 111: Work piece 124: Electrode

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Michio Omiyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Ichiro Aoki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation (56) Reference JP-A-58-160018 (JP, A) JP-A-59-134657 (JP, A) JP-B-59-32253 (JP, B2)

Claims (1)

[Claims] 1. A discharge electrode having a shape corresponding to a planned machining shape of a work piece, a first supporting means for supporting the discharge electrode, and a second support for supporting the work piece. Means, first measuring means attached to said first supporting means, second measuring means attached to said second supporting means, said first supporting means and said second supporting means A method for correcting machining in an electric discharge machine, comprising: a moving means for relatively moving and, storing information about a planned machining shape of the workpiece and its position, The relative movement of the first support means with respect to the second support means is measured, and the position of the first measurement means with respect to the second measurement means is determined based on the measured relative movement. Before moving to the first support means The second measuring means is brought into contact with a plurality of positions on the surface of the discharge electrode, and the position of the discharge electrode is determined based on the moving direction and distance of the second supporting means with respect to the first supporting means. And stores information on the position of the discharge electrode, and stores information on a plurality of positions on the surface of the discharge electrode with which the second measuring means is brought into contact, and the first supporting means is Based on the moving direction and the distance of the first supporting means with respect to the second supporting means at that time, the first measuring means is brought into contact with the workpiece by moving it with respect to the second supporting means. , Measuring the position of the workpiece, storing the information, and the current position of the discharge electrode from the stored information about the position of the discharge electrode and the planned machining shape of the workpiece and information about the position Scheduled processing of the workpiece for Information on the direction and distance to the position of the shape is obtained, a machining target is set based on the information, and the first supporting means is set to the second supporting means.
The workpiece is processed by the discharge electrode by moving it with respect to the supporting means, and the stored information of a plurality of positions on the surface of the discharge electrode and information about the planned machining shape of the workpiece and the position thereof. Based on the information of a plurality of positions of the planned machining shape of the workpiece corresponding to the plurality of positions on the surface of the discharge electrode, based on the information, the first measuring means to schedule the workpiece By moving the first supporting means with respect to the second supporting means with the plurality of positions of the processed shape as targets, a plurality of positions of the surface of the processed portion after processing of the workpiece are brought into contact with the plurality of positions. The position of the processing portion is measured based on the moving direction and distance of the first supporting means with respect to the second supporting means at that time, the information is stored, and the stored processing of the workpiece is performed. For the shape and position of the later processing part Based on the information and the information on the planned machining shape of the workpiece and the position thereof, the deviation between the position of the processed portion of the workpiece after machining and the position of the planned machining shape of the workpiece is calculated, In the subsequent machining, the correction machining method in an electric discharge machine is characterized in that the machining target is corrected in a direction to correct the deviation and then the correction machining is performed.