JPH05104333A - Diesinking electric discharge machine - Google Patents

Abstract

PURPOSE:To provide a diesinking electric discharge machine capable of automatically correcting each axis according to displacement of a Z-axis head and deflection of an axis displaced relative to the other axes even if the Z-axis head is displaced by the weight of an electrode or reaction(load) or if the axis (X- or Y-axis) displaced relative to the other axes by displacement of the Z-axis head is deflected. CONSTITUTION:When a movable table is used, a plurality of first amounts of errors in Z-axis position that could be caused each time a load (the weight of an electrode or reaction) is applied to an Z-axis head 7 are stored in a corresponding Z-axis error amount data memory 23 and a load measuring means 24a measures loads applied to the Z-axis head 7 during machining and the first amounts of errors in Z-axis are extracted from the loads and a first Z-axis coordinate decided according to a preset machined shape is automatically corrected by an X-axis coordinate correction means 24d. Also when a fixed table is used any axis displaced relative to the other axes by loads is automatically corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die-sinking electric discharge machine, and in the case of a table movable type, when an electrode is attached to a Z-axis head, the weight of the electrode or the electrode is moved toward and away from a workpiece. The present invention relates to a die-sinking electric discharge machine that automatically corrects the Z-axis coordinates when the Z-axis head is displaced by the reaction force generated in the gap. In the case of the table fixed type, when the electrode is attached to the Z-axis head, the Z-axis head is displaced by the weight of the electrode or the reaction force generated in the gap when the electrode approaches and separates from the workpiece. The present invention relates to a die-sinking electric discharge machine which automatically corrects the relative movement axis when the relative movement axis is displaced by the bending of the X, Y axis saddle.

[0002]

2. Description of the Related Art FIG. 8 is a schematic view showing an example of a conventional table-moving type die-sinking electric discharge machine. In the figure, 1 is a bed, 2 is an X-axis table installed on the bed 1, 3 is a Y-axis table installed on the X-axis table 2, 4 is a workpiece fixed on the Y-axis table 3, 5 is a processing tank for immersing the workpiece 4 in the processing liquid, 6 is a column which is fixed to the bed 1 and whose upper portion is a horizontal beam 6a having a predetermined length (hereinafter referred to as a column), 7 is a column 6 Horizontal beam 6
The Z-axis head provided at the tip of a and having the electrode attachment portion 7a attached to the lower portion, 8 is attached to the electrode attachment portion 7a of the Z-axis head 7, and the electrode attachment portion 7a is driven to attach to the workpiece 4. It is an electrode that approaches or separates from the electrode.

In a die-sinking electric discharge machine as shown in the figure, when a machining shape such as a circle is to be obtained, an electrode 8 is attached, and when an instruction to start machining is given, an NC device (not shown) causes an X-axis table. 2, each coordinate value from the Y-axis table 3 and the Z-axis head 7 is read, the difference from preset absolute coordinates is set as a reference correction value at the start of processing, and a command based on the processing shape is used as a reference correction value. Based on the above, the command to the X-axis table 2 and the Y-axis table 3 is corrected and output to the servo motor unit, and the command to the Z-axis head 7 is commanded at the start of machining by the reference correction value of the Z-axis head 7. To do.

Then, the electrode 8 is DUWed at a predetermined vertical distance.
N or UP (hereinafter referred to as JUNP operation),
Set the X-axis table 2 and Y-axis table 3 to the arrow X ± direction, Y ±
Direction and Z ± directions, respectively, to move the electrode 8 toward and away from the workpiece 4 fixed to the machining tank 5, and to insert a machining liquid in the minute gap between these electrodes and the workpiece 4. It was carving and discharging.

At this time, for example, when the area of the electrode 8 is large, the reaction force generated in the gap between the electrode 8 and the workpiece 4 becomes large, and the column 6 bends in the Z + direction in some cases,
Further, even if the NC device gave an instruction to DUWN a predetermined vertical distance, the vertical distance could not be DUWNed.

Further, as the machining progresses and the shape of the die-sinking (hereinafter referred to as the recess) becomes deeper, the reaction force is further increased because it is determined by the depth of the recess, the state of the working liquid and the area of the electrode 8. Further, when UP was performed, the electrode 8 was pulled down by the drag force due to the viscosity of the working liquid flowing through the gap between the electrode 8 and the side surface of the workpiece 4.

FIG. 9 is a schematic block diagram of a conventional die-sinking electric discharge machine of a table fixing type. In the figure, 4 to 7 are the same as those in FIG. 8, 10 is a bed on which the processing tank 5 is placed and fixed, and an X-axis saddle described later has a movable side fixed portion, and 11 is a bed. An X-axis saddle provided on one side of the bed 10 and driven in the arrow X ± directions, 12 is installed on the X-axis saddle 11, and a Z-axis head 7 is connected to the tip portion to drive in the arrow Y ± directions. It is a Y-axis saddle.

In such a system, a lifting mechanism for the processing tank 5 can be easily realized, and a large open space can be obtained by lowering the processing tank 5, so that the workpiece 4 is mounted on the table. The advantage is that setup work such as parallel alignment can be done easily.

In the case of the table fixing method shown in FIG. 9, for example, when a machining shape such as a circle is obtained, when a machining start instruction is issued, N
The C device reads each coordinate value from the X-axis saddle 11, the Y-axis saddle 12, and the Z-axis head 7, sets a difference from a preset absolute coordinate as a reference correction value during operation, and based on the machining shape. Based on the reference correction value, the command is output to the servo unit while correcting the commands to the X-axis saddle 11 and the Y-axis saddle 12 (hereinafter collectively referred to as relative movement axis), and Z
The command to the shaft head 7 includes a command based on the reference correction value,
Command a preset power.

Then, the electrode 8 is operated by JUNP so that the X-axis saddle 11 and the Y-axis saddle 12 are moved in the directions of the arrow X ±, Y in FIG.
By driving and controlling the electrodes in the ± direction and the Z ± direction, respectively, and by vertically moving the electrode mounting portion 7a of the Z-axis head 7, the electrodes 7 are moved toward and away from the workpiece 4 fixed to the machining tank 5, The machining liquid was interposed in a minute gap between the workpiece 4 and the workpiece 4 to perform the die-sinking discharge.

At this time, since the Y-axis saddle 12 is axially moved with time, the Y-axis saddle 12 is held by the X-axis saddle 11 at the base end, but the weight applied to the base end is Y.
It becomes larger according to the moving distance of the shaft saddle 12, Y
The shaft saddle 12 is deflected and, as a result, the Y-axis head 7 is lowered, so that a negative position error appears on the Z-axis of the electrode 8, and the Z-axis is machined deeper than the machining shape command of the NC device.

Further, when the Y-axis saddle 12 is axially moved in the plus direction, conversely, the weight applied to the base end of the X-axis saddle 11 becomes smaller and the deflection becomes smaller than at the start, so that the machining shape of the NC device is reduced. Was processed shallower than the order of.

Further, in the case of deep simple engraving, the Z-axis position of the electrode 8 is different from the command value of the NC device at the time of JUNP when the recess is deep, as in the above-mentioned table movable type. This tendency becomes more remarkable as the weight and area of the electrode 8 increase, and the X-axis saddle 11 and the Y-axis saddle 12
Since the length of the electrode 8 does not change, it is shortened by bending, and as a result, the X-axis and Y-axis coordinates of the electrode 8 also change.

That is, the Z-axis head of the conventional electric discharge machine is in the state shown in the figure below. In this case, FIG. 11 will be described as an example. FIG. 10 shows A of FIG. 9 when the electrode is attached.
It is an arrow view. In the figure, 7 to 12 are the same as those in FIG. 10. In the figure, the Y-axis saddle 12 (horizontal beam 6a in FIG. 8) is horizontal before the electrode 8 is attached to the electrode attachment portion 7a. When attached, it indicates that the weight bends in the negative Z-axis direction.

FIG. 11 is a view taken in the direction of arrow A in FIG. 9 when an electrode is attached and electric discharge machining is performed. In the figure, 5 to 12 are shown in FIG.
13 is a processing liquid. The figure shows the DUWN when the electrode 8 is attached and simple engraving is performed.
When a command is issued to cause a reaction force with a large gap to act, the reaction force causes the electrode 8 to lift and Y in a moment.
This shows that the shaft saddle 12 is being lifted.

If the rigidity of the Y-axis saddle 12 is increased in order to reduce the deflection of the Z-axis saddle 12, the cost is increased and the weight of the Y-axis saddle 12 is increased, and the Y-axis saddle 12 and the X-axis saddle 12 are also heavy. The weight that the servo motor must drive has increased, and the load on the Y-axis saddle 12 and the X-axis servo motor has increased.

Even if these are allowed, in principle, when the Y-axis saddle 12 is moved axially, a deflection in the negative Z-axis direction occurs, and the amount of positional deflection in the negative or positive Z-axis direction of the electrode 8 is caused. Was becoming. Therefore, the following processing is performed.

FIG. 12 is a schematic configuration diagram of a position error correction method of a conventional electric discharge machine. In this case, the case of using the XY table fixed type of FIG. 9 will be described. 14 is an input device, 15 is a CPU, 16 is a memory, 17 is an X-axis servomotor with an encoder, 18 is a Y-axis servomotor, 19
Is a Z-axis servomotor.

FIG. 13 is a view for explaining the data of the Z-axis electrode position error with respect to the Y-axis saddle movement amount of the memory. In this case, the Y-axis saddle 12 has a stroke of 400 mm, and Y = -1 as the Y-axis saddle 12 moves in the negative direction of the Y-axis.
The relative position error amount in the Z-axis direction is -3 μm at Y = 00 mm, Y =
-The relative position error amount in the Z-axis direction at the position of 400 mm is-
This shows that the value is stored as 20 μm. It also stores the error amount of the Z-axis saddle with respect to the X-axis saddle movement amount.

The conventional system as described above uses the Y-axis saddle 1
When 2 operates, the input device 14 outputs a movement command representing a desired three-dimensional shape as a set of digital quantities using an appropriate coordinate system to the CPU 15.

Based on the movement distance Y included in the given movement command and the Z-axis electrode position error stored in the memory 16, the CPU 15 generates in the Z-axis negative direction with the execution of the Y-axis movement command. Z-axis electrode position error CPU15
Based on the Z-axis electrode position error calculated and calculated, the Z-axis electrode position error value is given a negative sign and input to the Z-axis servomotor 19 to drive it. So far,
Although the Z-axis position error correction function for the Y-axis position has been described, the Z-axis position error correction function for the X-axis position is also driven by the same configuration and operation.

However, since the position error correction amount does not take into consideration the weight of the electrode 8 and the repulsive force of the gap, when the weight of the electrode 8 becomes large, the machining cannot be performed accurately. . As a means for solving such a problem, JP-A-59-8
No. 8242 and Japanese Patent Laid-Open No. 62-171633 are disclosed.

However, the squareness error correction method for machine tools disclosed in Japanese Patent Laid-Open No. 59-88242 detects whether each saddle has a right angle, and if it does not have a right angle, it is stored in advance. The saddle position is controlled based on the correction amount, and even in this case, the correction amount does not consider the electrode 8 and the repulsive force.

Further, the electric discharge machining apparatus disclosed in Japanese Patent Laid-Open No. 62-171633 corrects that the moving amount of each XY table is different according to the remaining amount of the working liquid by the correction amount stored in advance. However, it is not a correction amount in consideration of the control about the Z axis and the electrode 8 and the repulsive force. Further, the machining reaction force is described in detail in VOL NO 39, "A Study on Mechanical Properties in Actual Operation of Electric Discharge Machines", published by the Institute of Electrical Machining.

[0025]

In the die-sinking electric discharge machining apparatus configured as described above, (1) in the case of the table movable system, the NC apparatus issues a command to the servo unit to DUWN a predetermined vertical distance. Even
The command does not consider the reaction force, so if the area of the electrode increases, the reaction force generated in the gap will increase.
There is a problem in that the electric discharge cannot be performed at a predetermined depth without DUWNing the target vertical distance, and the processing speed becomes slow.

(2) Further, as the processing progresses and the recess becomes deeper, the tendency becomes stronger, and at the time of UP, the drag is lowered downward by the drag force of the fluid between the electrode and the side surface of the gap, and the target UP distance cannot be reached. When machining, J moves from its UP position to DUWN and reaction force acts on it.
Since the UNP operation is performed, there is a problem that the vertical distance commanded by the NC device is not JUNPed, discharge cannot be performed at a predetermined depth, and the machining speed becomes slow.

(3) Further, the table fixed type electric discharge machining apparatus has the problem of the above (1) when performing a simple die-sinking discharge, and when machining a machining shape such as a circle or a cube. When a machining start instruction is issued, a reference correction value is set based on the coordinate values of the X-axis saddle, Y-axis saddle, and Z-axis head, and thereafter, a command based on the machining shape is set for each axis based on the reference correction value. When a command to correct is issued, but the electrode weight becomes heavy, the Y-axis saddle bends and the X-axis, Y-axis, and Z-axis displace,
There is a problem that accurate machining may not be possible depending on the machining shape.

(4) Further, since the correction is performed only by the reference correction value without considering the reaction force at the start of processing, there is a problem that the amount of deflection increases due to the reaction force, which further deteriorates the processing accuracy. It was

(5) Further, the position error correction method for solving the above problems is not the position error correction amount in consideration of the weight of the electrode on which the electrode is mounted and the repulsive force of the gap. However, there is a problem in that the processing cannot be performed according to the processing shape when the value becomes large.

(6) Further, the squareness error correction method detects whether or not each saddle is at a right angle, and if not, controls the saddle position based on a correction amount stored in advance. However, even in this case, the amount of correction was not in consideration of the electrode 8 and the repulsive force.

(7) Further, since neither of JP-A-59-88242 and JP-A-62-271633 is a correction amount in consideration of the electrode weight and the repulsive force, it is possible to accurately adjust the processed shape. There was a problem that it could not be processed.

The present invention has been made in order to solve the above problems, and by setting the correction value in consideration of the weight and reaction force of the electrode, the load of the electrode (table movable type or table fixed type) ( Even if the Z-axis head is displaced due to the electrode weight or reaction force or the relative movement axis (X-axis or Y-axis) is deflected due to the displacement of the Z-axis head, each axis is moved according to the displacement or the deflection of the relative movement axis. An object of the present invention is to obtain a die-sinking electric discharge machining apparatus that can perform automatic correction and perform machining according to a machining shape quickly and accurately.

[0033]

According to the die-sinking electric discharge machining apparatus of the present invention, during machining, the first servo section for controlling the Z-axis head and the XY-axis table changes the machining shape of the workpiece. The first Z-axis coordinate commanded based on this is set, and the electrode mounted on the Z-axis head is moved toward and away from the workpiece, while the workpiece is injected into the machining tank in the machining tank. In a table movable die-sinking electric discharge machine having a first servo control means for making a predetermined machining gap to perform electric discharge machining, the weight of the electrode when attached to the Z-axis head Alternatively, the displacement amount by which the Z-axis head is displaced by the reaction force when the electrode is moved closer to and away from the workpiece is defined as the first Z-axis position error amount, and the first Z-axis is determined for each load.
A Z-axis error amount data memory in which a plurality of axial position error amounts are associated and stored, and a reaction force generated in the gap when the weight or the electrode attached to the Z-axis head approaches or separates from the workpiece. Is measured as a load applied to the Z-axis head at predetermined time intervals and is output as a measured load, and a first Z-axis error amount corresponding to the measured load is extracted from the Z-axis error amount data memory. When the first Z-axis error amount extraction means for outputting and the first Z-axis error amount are output, the first Z-axis coordinate set in the first servo control means is changed to the first
And a Z-axis coordinate correcting means for correcting the Z-axis coordinate error amount. Further, when the first Z-axis error amount corresponding to the load is not extracted from the first Z-axis error amount extraction means, the range of the measured load is set based on the measured load and the load of the memory for Z-axis error amount data. It is provided with a Z-axis coordinate error amount calculating means for calculating the Z-axis error amount corresponding to the measured load from the obtained range and outputting it as the first Z-axis error amount to the Z-axis coordinate correcting means. Furthermore, during processing, the X-axis saddle,
In the second servo unit that moves the Y-axis saddle and the Z-axis head relative to each other, the relative axis coordinates commanded based on the machining shape of the workpiece are set, and the electrode attached to the Z-axis head is machined. While approaching and moving away from the object, a predetermined machining gap is created for the workpiece in the machining tank into which the machining fluid is injected to perform electric discharge machining, and the X-axis saddle, Y
In a table-fixing type die-sinking electric discharge machining apparatus having a second servo control means for moving a shaft saddle relative to the axis, a Z-axis head is provided with an electrode to attach a Y-axis saddle or X-axis.
When the axis saddle is moved relative to the Y axis saddle or X
The displacement amount of the Z-axis head due to the deflection amount of the shaft saddle is set as a second Z-axis error amount, and the movement amount of the Y-axis saddle or the X-axis saddle and the second amount are set for each load (electrode weight or reaction force) of the Z-axis head. A memory for each axis error amount data in which a plurality of flexure characteristic data indicating the Z axis error amount are stored, a load measuring means for measuring a load applied to the Z axis head every predetermined time, and a direction of relative axis movement is read, Deflection characteristic selection means for selecting the deflection characteristic data corresponding to that direction and corresponding to the load measured by the load measuring means from the memory for each axis error amount data, and notifying the selected deflection characteristic data, and the Y-axis saddle Or read the actual amount of relative axis movement of the X-axis saddle every predetermined time,
Second Z-axis error amount extraction means for extracting a second Z-axis error amount corresponding to the actual relative axis movement amount of the Y-axis saddle or the X-axis saddle from the selected deflection characteristic data, and second Z-axis When the error amount is extracted, the Z-axis set value of the relative movement axis set in the second servo control means is corrected based on the second Z-axis error amount, and the Z-axis correction value is used. Second
Each of the servo control means is provided with each axis position correcting means for correcting the set values of the Y axis and the X axis. Further, when the flexure characteristic data is not selected by the flexure characteristic selecting means, the measured load and the relative movement axis coordinate are read, and based on the load stored in the memory for each axis error data,
The range of the measured load and the relative movement axis is obtained, and the deflection characteristic data corresponding to the measured load is created from the range, and the second Z
It is provided with a deflection characteristic calculation means for outputting to the axial error amount extraction means.

[0034]

In the present invention, when the table is movable,
Load (electrode weight or reaction force) applied to the Z-axis head when an electrode is attached to the Z-axis head in the Z-axis error amount data memory
The first Z-axis position error amount due to is stored for each load.
Then, the load measuring means measures the load applied to the Z-axis head at predetermined time intervals and outputs it as the measured load to the first Z-axis error amount extracting means.

Next, the first Z-axis error amount extraction means extracts the first Z-axis error amount corresponding to the measured load from the Z-axis error amount data memory and outputs it to the Z-axis coordinate correction means.

When the first Z-axis error amount is output, the Z-axis coordinate correcting means sets at least the first Z-axis coordinate set in the first servo control means for issuing a command to drive the Z-axis head. In the machining tank in which the machining fluid is injected while performing the correction based on the first Z-axis error amount and causing the electrode attached to the Z-axis head to approach and separate from the workpiece by the first servo unit. A predetermined machining gap is created for the workpiece to be subjected to electric discharge machining.

Further, when the Z-axis coordinate error amount calculating means is provided, if the first Z-axis error amount corresponding to the load is not extracted, the Z-axis coordinate error amount calculating means stores the load as the measured load. Based on the above, the range of the measured load is obtained, the Z-axis error amount corresponding to the measured load is calculated from the range, and is output to the Z-axis coordinate correction means as the first Z-axis error amount, thereby correcting the Z-axis coordinate. The means corrects the first Z-axis coordinate based on the first Z-axis error amount.

Further, in the case of the table fixed type, the relative axis movement amount and the Z axis position error amount corresponding to the load when the electrode is attached to the Z axis head is stored in the memory for each axis error amount data as deflection characteristic data. Remember each time.

Then, the load measuring means measures the load applied to the Z-axis head at every predetermined time, the deflection characteristic selecting means reads the direction of the relative axis movement, corresponds to the direction, and is measured by the load measuring means. Select the deflection characteristic data corresponding to the load from the memory for each axis error amount data
Notify the Z-axis error amount extraction means.

Next, the second Z-axis error amount extraction means reads the actual relative axis movement amount of the Y-axis saddle or the X-axis saddle at predetermined time intervals, and selects the Y-axis saddle or the X-axis from the selected deflection characteristic data. The second Z corresponding to the actual relative axis movement of the saddle
Extract the amount of axis error.

Next, the respective axis position correcting means are provided with the extracted second
Based on the Z-axis error amount and the second Z-axis coordinate set in the second servo control means, the second Z-axis correction value due to the flexure is obtained, and the second Z-axis coordinate is set to that value. In addition to the correction, the Y-axis and X-axis set values set in the second servo control means are corrected by the corrected second Z-axis coordinates, so that the electrode attached to the Z-axis head is processed. While approaching and moving away from each other, a predetermined machining gap is created for the workpiece in the machining tank into which the machining fluid is injected to perform electric discharge machining, and the X-axis saddle and the Y-axis saddle are relative to each other. The axis is moved and processed.

Further, in the case where the flexure characteristic calculating means is provided, if the flexure characteristic data is not selected, the flexure characteristic calculating means reads the measured load and the relative movement axis coordinate, and the load stored in the memory for each axis error data. Based on, the range of the measured load and the relative movement axis is obtained, the deflection characteristic data corresponding to the measured load is created from the range, and the deflection characteristic data is output to the second Z-axis error amount extraction means. The second Z-axis error amount corresponding to the actual relative axis movement amount of the Y-axis saddle or the X-axis saddle is extracted, and the set relative movement axis is corrected by each axis position correction means.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic configuration diagram of a table-moving type die-sinking electric discharge machine of the present invention. In this case, the CPU is used, but the configurations such as I / O and A / D are omitted, and in this case, the load is measured by the electrode weight,
Further, it is assumed that the area of the electrode 8 is small and that the state of the working liquid does not change so much and the working reaction force can be ignored.

In FIG. 1, 1 to 8 are the same as the above, 21 is an electrode weight detection sensor, which is incorporated in the Z-axis head 7 and is, for example, the journal of the Institute of Electrical Processing, VOL NO.
The crystal type piezoelectric load sensor shown in FIG.
Is detected and output as an electrode weight detection signal.

Reference numeral 23 is a memory for Z-axis error amount data,
When the electrode 8 is attached to the Z-axis head 7, the Z-axis head 7
Z-axis position error amount data (hereinafter referred to as Z-axis position error amount) corresponding to a plurality of predetermined electrode weights is stored in advance as the Z-axis position error amount for each predetermined position. Is. In this case, the table moving type die-sinking electric discharge machine has a Z-axis position error amount described below.

FIG. 2 is a view for explaining the Z-axis position error amount of the table movable type die-sinking electric discharge machine. In the figure, the vertical axis represents the Z-axis position error amount ΔZ (L), and the horizontal axis represents the movement amount of the Y-axis table 3, for example, a (0 Kg), b (50 K
g), c (100 Kg) and d (150 Kg) electrodes 8 are attached to show the relationship between the movement amount of the Y-axis table 3 and the Z-axis position error amount ΔZ (L), and the electrode 8 approaches the workpiece. In this case, the processing reaction force generated in the gap is neglected.

As shown in this figure, in the table moving method, the Z-axis position error amount ΔZ (L) does not depend on the movement amount of the Y-axis table 3. Therefore, in the table moving method, the Z-axis position error amount ΔZ (L) shown in Table 1 below is set as a function (L) of the electrode weight.
Store as.

[0048]

[Table 1]

Reference numeral 24 is a Z-axis correction unit, which has the components described below. Reference numeral 24a is a load measuring means, which reads an electrode weight detection signal from the electrode weight detection sensor 21, measures the electrode weight from the electrode weight detection signal, and outputs it as a measured electrode weight.

Reference numeral 24b is a first Z-axis error amount extraction means, and the Z-axis position error amount corresponding to the measured electrode weight is Z.
If it is stored in the memory 23 for axis error amount data,
The corresponding Z-axis error amount is extracted and output.

Reference numeral 24c is a first Z-axis error amount calculation means, and it is assumed that the Z-axis error amount ΔZ (L) corresponding to the electrode measured by the first Z-axis error amount extraction means 24b is not stored. In this case, the measurement electrode weight is read from the load measuring means 24a, the lower limit electrode weight and the upper limit weight that are closest to the measurement electrode weight are read, and the ranges are defined as the measurement electrode weight range (L1
And L2), and the Z-axis position error amount ΔZ (L) is calculated from the range by the following well-known interpolation method and output.

Reference numeral 24d is a Z-axis coordinate correction means, which reads the Z-axis coordinate Z1 set in the first servo control section by the NC when a processing start instruction is given, and first Z-axis error amount extraction means 24a. Alternatively, the correction value (Z2) when the Z-axis head 7 is displaced is obtained from the Z-axis position error amount ΔZ (L) from the first Z-axis error amount calculation means 24c, and the correction value (Z
2) The Z-axis coordinate Z1 set in the first servo control unit
Is to correct.

Reference numeral 25 is a first servo control unit, the operation and configuration of which are the same as those of the conventional one.
The coordinate values of the axis head 7 and the X-axis and Y-axis coordinates of the XY table are set, and the respective set coordinate values are output to the first servo unit (not shown) as respective control signals, While the electrode 8 attached to the Z-axis head 7 is moved toward and away from the workpiece 4, a predetermined machining gap is formed with respect to the workpiece 4 fixed in the machining tank 5 into which the machining liquid is injected. Create and perform electrical discharge machining.

The operation of the die-sinking electric discharge machine of FIG. 1 constructed as described above will be described below. FIG. 3 is a flow chart for explaining the operation of the die-sinking electric discharge machine of the present invention in FIG. For example, in the case of a table movable system, when an electrode 8 of 125 kg is attached to the Z-axis head 7 and a processing start instruction is issued, the Z-axis coordinate correction means 24d of the Z-axis correction unit 24 attaches the electrode 8 as an initial setting. The Z-axis coordinate at that time is obtained by an encoder or the like and preset as the coordinate Z1 (S100).

Then, the load measuring means 2 of the Z-axis correction unit 22
4a reads the electrode weight detection signal from the electrode weight detection sensor 21 and measures the electrode weight based on the electrode weight detection signal (S101).

Next, the load measuring means 24b of the Z-axis correction unit 24
Determines whether the measured electrode weight is stored in the Z-axis error data memory 23 (S102). If it is not stored, the first Z-axis error amount calculation means 24c is notified that it is not stored.

Then, the first Z-axis error amount calculating means 24c
Reads the electrode weight measured from the load measuring means 24c, reads the electrode weight L of 50 kg, 100 kg, and 150 kg stored in the Z-axis error data memory 23, and 0 ≦ L <
It is determined whether the range is 50, 50 ≦ L <100, or 100 ≦ L <150 (S103).

Next, if 0 ≦ L <50, the electrode weight range is L1 = 0, L2 = 50 or L1 = 50, L2 = 10.
It is set as 0 or L1 = 100 and L2 = 150 (S104). In this case, since the electrode 8 weighs 125 kg, it is determined that 100 ≦ L <150, and the electrode weight ranges L1 = 100 and L2 = 150 are set.

Next, the Z-axis error amount calculation means 24c of the Z-axis correction unit 24 performs Z corresponding to L1 = 100 and L2 = 150.
Axial position error amount ΔZ (L1) and Z-axis position error amount ΔZ (L
2) is read from the Z-axis error data memory 23.

In this case, the Z-axis position error amount ΔZ (L1) = Δ corresponding to the electrode weights of 100 kg and 150 kg shown in Table 1.
Z (100) = − 6 and Z axis position error amount ΔZ (L2) =
Read ΔZ (150) =-10.

Then, based on the following formula 1, the electrode weight 1
A Z-axis position error amount ΔZ (L) of 25 Kg is obtained as shown in Expression 2 and output to the Z-axis coordinate correction means 24d (S10).
5).

[0062]

[Equation 1]

That is, Z-axis position error ΔZ (L) =-8 μm
Was found, and the 125 kg electrode 8 was attached,
The Z-axis head 7 is shown displaced by -8 μm.
Next, the Z-axis coordinate correcting means 24d causes the Z-axis position error ΔZ (L) = − 8 μm from the first Z-axis error amount calculating means 24c.
Then, the Z-axis coordinate Z2 to be newly corrected is obtained from the Z-axis coordinate Z1 which has been set by the equation (2) (S106).

[0064]

[Equation 2]

In this case, if Z1 = 30.0 mm, for example, Z2 = 30.0-(-0.008) = 30.08. As a result, the first servo control means 25 moves the Z-axis motor to 30.08 mm, and Z
It is possible to correct the displacement of the shaft.

Similarly, when the electrode weight becomes 100 kg,
Z-axis position error amount ΔZ (L) = − 6 μm, so Z2 = 3
It becomes 0.006 mm. Further, if the electrode weight is stored in step S102, the first Z-axis error amount extraction means 24b of the Z-axis correction unit 24 causes the corresponding Z-axis position error amount Δ.
Z (L) is read from the Z-axis error data memory 23, and the value is output to the Z-axis coordinate correction means 24d to obtain the Z-axis coordinate Z2. Next, the configuration and operation of the fixed table type will be described below.

FIG. 4 is a schematic block diagram of the electric discharge machining apparatus of the present invention of a fixed table type. In the figure, 4 to 24a are the same as above.

Reference numeral 30 is a memory for each axis error data, and when a predetermined electrode is attached to the Z-axis head 7, the Y-axis bends when the Y-axis saddle 12 is moved, and the amount of displacement of the Z-axis is set. As the Zy-axis position error amount for each predetermined position, Y is used as the deflection characteristic data corresponding to each predetermined electrode weight.
The amount of displacement of the Z-axis when the X-axis saddle is moved is stored in advance in the X-axis-Z-axis error amount data region as the Zx-axis position error amount, respectively. It is a thing. The movements of the X axis, Y axis, and Z axis are collectively referred to as relative movements.

FIG. 5 is a diagram for explaining each axis position error data in the memory for each axis position error data. In this case, the Y-axis
The Z-axis error amount data will be described as an example. In the figure, the vertical axis is Z
The y-axis position error amount ΔZ (y, L) is set, and the horizontal axis is set as the movement amount of the Y-axis saddle 12, for example, a (0 Kg), b (50 K
g), c (100 Kg), and d (150 Kg) electrodes 8 are attached to show the relationship between the movement amount of the Y-axis saddle 12 and the Z-axis position error amount ΔZ (y, L). The processing reaction force generated when the electrode 8 approaches the workpiece 4 is neglected.

Like the flexural characteristic data shown in this figure,
In the table fixing method, the Z-axis position error amount ΔZ (y, L) is displaced depending on the movement amount of the Y-axis saddle 12. Therefore, the Z-axis position error amount ΔZ (y, L) shown in Table 2 below is stored as a function (y, L) of the electrode weight.

[0071]

[Table 2]

Reference numeral 31a is a deflection characteristic selecting means, and when the electrode weight measured by the load measuring means 24a is stored, the moving direction of the Y-axis saddle 12 or the X-axis saddle 11 is obtained from its actual coordinate value. Deflection characteristic data corresponding to the calculated axial electrode weight is selected from the memory 30 for each axis error data, and the selected deflection characteristic data is used as the selected deflection characteristic data. Is output to.

Reference numeral 31b is a deflection characteristic calculating means, which is informed that the selected deflection characteristic data is not stored, reads the electrode weight measured by the load measuring means 24a, and based on the range of the measured electrode weight. Read the two deflection characteristics, and Y-axis saddle 12 or X-axis saddle 1
Read the actual coordinate value of 1, and based on the coordinate value, L1
And the Z-axis position error amount ΔZ of the Y-axis saddle 12 or the X-axis saddle 11 for each flexure characteristic of L2, and the flexure characteristic data is created from the obtained two Z-axis position error amounts to create a second Z-axis which will be described later. It is output to the error amount extraction means. However,
In this case, the formula when the Y-axis saddle 12 moves is defined as X
Since the shaft saddle 11 is similar, the formula is omitted.

Reference numeral 31c is a second Z-axis error amount extracting means, which is moved when the selected deflection characteristic data from the deflection characteristic selecting means 31a or the deflection characteristic from the deflection characteristic calculating means 31b is notified. The actual coordinate value of the X-axis saddle 11 is read, the Z-axis position error amount is obtained from the selected deflection characteristic data based on the coordinate value, and the Z-axis position error amount is output to the axis coordinate correcting means described later.

Reference numeral 31e is an axis coordinate correcting means, which is the second Z
When the Z-axis error amount is output from the axis-error-amount extracting means 31c, a second command is issued to perform relative axis movement control of the X, Y, and Z axes.
The Z-axis coordinate (Z1) from NC set in the servo control means 32 is corrected based on the Z-axis error amount, and the X and Y-axis coordinates set by the corrected coordinate are corrected.

The operation of the table-fixing type die-sinking type electric discharge machining apparatus of the present invention configured as described above will be described below. 6 and 7 are flow charts for explaining the operation of the present invention of the fixed table type. In this case, the electrode 8
The area of is small and the processing reaction force can be ignored, and a case where the Y-axis saddle 12 is moved will be described.

When the Y-axis saddle 12 is moved to a predetermined position and an instruction to start machining is given, the deflection characteristic selection means 31a, the deflection characteristic calculation means 31b, and the second Z-axis error amount calculation means 3
1c, as an initial setting, the relative movement axis coordinate when the electrode 8 is attached is obtained by an encoder or the like, and the Z axis coordinate is preset as the coordinate Z1 (S200).

Then, the load measuring means 24a reads the electrode weight detection signal from the electrode weight detection sensor 21, measures the electrode weight based on the electrode weight detection signal, and outputs it to the deflection characteristic selecting means 31a (S201).

The flexure characteristic selecting means 31a stores the flexure characteristic data corresponding to the actual moving direction of the relative moving axis and corresponding to the measured electrode weight in each axis error data memory 30.
If it is stored, the address area is notified (S202). When the flexure characteristic selecting means 31a is notified from the flexure characteristic selecting means 31a that the corresponding flexure characteristic data is not stored, the measured electrode weight of the load measuring means 24a is read, and the measured electrode weight is calculated for each axis. If the electrode weight L stored in the error data memory 30 is 0 ≦ L <50, 50
It is determined whether the range is ≦ L <100 or 100 ≦ L <150 (S203).

Next, based on the judged range, L1 = 0
And L2 = 50, L1 = 50 and L2 = 100, L1 =
Electrode weight range L1 of either 100 or L2 = 150
And L2 are set (S204).

Next, the Y-axis saddle 12 or the X-axis saddle 11
Read the actual coordinate values of Y-axis saddle 12 or X-axis saddle 1
The movement range of 1 is set (S205). In this case, Y
Since the movement of the shaft saddle 12 is −100 <y ≦ 0, −2
00 <y ≦ −100, −300 <y ≦ −200, −40
It is determined whether the movement range is 0 <y ≦ −300.

Next, based on the moving range, y1 = 0 and y2 = -100, y1 = -100 and y2 = -200 or y1 = -200 and y2 = -300 or y1 =-.
It is set as 300 and y2 = -400 (S20).
6).

Next, the two flexural characteristics corresponding to the electrode weight set from each axis error data memory 30 are read, and the actual coordinate values of the Y-axis saddle 12 or the X-axis saddle 11 are read and the coordinate values are set. Based on each of the bending characteristics of L1 and L2, the Z-axis position error amount ΔZ (y, L) of the Y-axis saddle 12 or the X-axis saddle 11 is obtained by the following equations 3 and 4, respectively, and the obtained two Z axes are obtained. Deflection characteristic data is created from the position error amount and output to the second Z-axis error amount extraction means 31c (S207).

[0084]

[Equation 3]

[0085]

[Equation 4]

However, in this case, the interpolation method is used, and the equation is used when the Y-axis saddle 12 is moved. Since the X-axis saddle 11 is the same, the equation is omitted. Then, the second Z-axis error amount extraction means 31c has the deflection characteristic data selected from the deflection characteristic selection means 31a or the deflection characteristic calculation means 31.
When the address area of the flexure characteristic data from b is notified, the actual coordinate value of the moved Y-axis saddle 12 or X-axis saddle 11 is read, and the selected flexure characteristic data of the address area is notified based on the coordinate value. The Z-axis position error amount is obtained by the equation 5 and output to the axis coordinate correcting means 31e (S208).

[0087]

[Equation 5]

Next, the axis coordinate correcting means 31e causes the second Z
When the Z-axis error amount is output from the axis-error-amount extracting means 31c, a second command is issued to perform relative axis movement control of the X, Y, and Z axes.
The Z-axis coordinate (Z1) from NC set in the servo control means 32 is corrected based on the Z-axis error amount shown in the following equation 6, and the X and Y-axis coordinates set by the corrected coordinate are It is corrected (S209).

[0089]

[Equation 6]

Further, corresponding to the electrode weight measured in step S202, the relative axis direction (in this case, the Y axis direction)
When the flexure characteristic selecting means 31a determines that the flexure characteristic data corresponding to is stored, the flexure characteristic data corresponding to the electrode weight is used as the second axis error amount extracting means 31c.
To the Z-axis position error amount ΔZ (y, y,
L) is extracted.

That is, when the deflection characteristic data corresponding to the measured electrode weight is not stored, for example, when the measured electrode weight L is 75 kg and y = -350 mm, L
1 = 50, L2 = 100, y1 = -300, y2 = -4
00, and from Equation 3 and Equation 4,

Z-axis position error amount ΔZ (y1, L) = − 24 Z-axis position error amount ΔZ (y2, L) = − 32 Therefore, the Z-axis position error amount ΔZ (y,
L) = − 28 is obtained, and y = by the load of 75 kg of electrode.
It shows that the Z axis is deflected by -28 μm at the position of -350 mm.

Then, the Z-axis correction value Z2
For example, if Z1 = 30.0 mm, Z2 = 300 − (− 0.028) = 30.028 However, Z1 is the Z-axis coordinate value before correction, and an error occurs in each axis due to deflection in an arbitrary range (y, L). It is possible to prevent the occurrence of.

Next, the weight and area of the electrode increase,
When the processing reaction force becomes non-negligible, the Z-axis head 8 compresses the processing liquid while the electrode 8 is close to the workpiece as described in the conventional example, and the processing reaction force is applied in the + direction of the Z-axis. ..

Therefore, for example, a table movable type will be described as an example. Z-axis position error ΔZ for repulsive force
It is stored in association with (L) as shown in Table 3.

[0096]

[Table 3]

Further, the first Z-axis error amount extraction means 24b is the first Z-axis error amount extraction means 24bb, the actual Z-axis coordinate value is read, and the Z-axis coordinate value is ± with respect to the absolute coordinate. Alternatively, the Z-axis position error amount corresponding to the determination result and corresponding to the electrode weight may be read from the memory, extracted, and the same process as the above-described operation may be performed. Therefore, when the Z-axis head 7 is brought closer to the workpiece 4, the processing reaction force is added, and the Y-axis saddle 12 bends in the + direction.
Even if is displaced, the Z-axis coordinate from NC can be corrected in the same way.
Stable processing is possible.

Further, in the case of the fixed table type, in the respective axis error data memory 30, the added value of the electrode weight and the machining reaction force in which the Z axis is in the ± directions with respect to the absolute coordinates, the Z axis for the electrode weight and the machining repulsive force. By storing the position error ΔZ (L) in association with the X and Y axes, the Z axis coordinates can be corrected in the same manner as above, and the X and Y axes can be corrected based on the correction values, and stable machining is possible. Becomes

In the above embodiment, the weight of the electrode 8 is detected to correct the Z axis or each axis. However, since the electrode weight and the processing reaction force correspond to each other, the well-known formula 7 below is used. The Z-axis or each axis may be corrected by calculating the processing reaction force based on the Stefan equation.

[0100]

[Equation 7]

In this case, the electrode weight detection sensor 21 is not necessary, and the load measuring means 2 stores the Z-axis position error amount corresponding to the processing reaction force instead of the electrode weight in the memory.
4a measures the processing reaction force based on the above equation 7.

However, the viscosity coefficient μ of the working fluid, the electrode moving speed V, the electrode radius r, the shortest inter-electrode distance h, and the electrode surface roughness R are previously set.
e, work surface roughness Rw is set as a parameter. Then, the actual Z-axis coordinate value is read at the moment when the electrode 8 starts the UP operation of the JUNP operation or reaches the lowest point,
The effective inter-electrode distance he may be obtained and the processing reaction force may be obtained based on the above equation 7. Therefore, although the load in the above embodiment is described as the electrode weight, it may be used as the processing reaction force.

[0103]

As described above, according to the present invention, in the case of the movable table type, the first Z-axis position error amount generated in advance is handled for each load (electrode weight or reaction force) applied to the Z-axis head. Then, a plurality of first Z-axis error amounts corresponding to the load applied to the Z-axis head are extracted during processing, and the first Z-axis coordinates determined by the preset machining shape are loaded. Since the correction is automatically performed based on the first Z-axis error amount corresponding to, the stable machining can be performed at high speed according to the machining shape even if the Z-axis head is displaced according to the electrode weight or the reaction force. The effect is obtained.

If the first Z-axis position error amount corresponding to the measured load is not stored, the Z-axis error amount corresponding to the measured load is calculated based on the measured load and the stored load. Then, since the first Z-axis coordinate is automatically corrected by the calculated Z-axis error amount, Z-axis is adjusted for any load.
The effect that the Z axis of the axial head can be corrected is obtained.

Further, in the case of the table fixed type, when the electrode is attached to the Z-axis head, the relative axial movement amount of the Y-axis saddle or the X-axis saddle and the second Z-axis position error amount of the Z-axis head are moved. The bending characteristic data of the shaft is stored and the second bending Z corresponding to the actual relative axis movement amount of the Y-axis saddle or the X-axis saddle is calculated from the bending characteristic data corresponding to the measured load during machining.
Since the axial position error amount is extracted and the preset X-axis, Y-axis, and Z-axis are corrected based on the second Z-axis position error amount, the amount of the axial position error is corrected according to the electrode weight or the reaction force. Even if the deflection axis coordinates of each axis are displaced, the effect that stable machining can be performed at high speed according to the machining shape is obtained.

Further, when the flexure characteristic data is not stored, the flexure characteristic data is calculated based on the measured load, and the second Z-axis position error amount is extracted from the characteristic, and the preset X value is set. Since the axes, the Y axis, and the Z axis are corrected, the relative movement axis can be corrected with respect to an arbitrary load (electrode weight or reaction force).

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a table movable type die-sinking electric discharge machining apparatus of the present invention.

FIG. 2 is a diagram illustrating a Z-axis position error amount of a table movable type die-sinking electric discharge machining apparatus.

FIG. 3 is a flow chart for explaining the operation of the die-sinking electric discharge machine of the present invention.

FIG. 4 is a schematic configuration diagram of an electric discharge machining apparatus of the present invention of a fixed table type.

FIG. 5 is a diagram illustrating each axis position error data of each axis position error data memory.

FIG. 6 is a flowchart for explaining the operation of the present invention of a fixed table type.

FIG. 7 is a flow chart for explaining the operation of the present invention of a fixed table type.

FIG. 8 is a schematic configuration diagram showing an example of a conventional movable table-type die-sinking electric discharge machine.

FIG. 9 is a schematic configuration diagram of a conventional die-sinking electric discharge machine of a table fixing type.

FIG. 10 is a view on arrow A of FIG. 9 when an electrode is attached.

FIG. 11: A in FIG. 9 when an electrode is attached and electric discharge machining is performed
It is an arrow view.

FIG. 12 is a schematic configuration diagram of a position error correction method of a conventional electric discharge machine.

FIG. 13 is a diagram illustrating data of a Z-axis electrode position error with respect to a Y-axis saddle movement amount of a memory.

[Explanation of symbols]

 1 Bed 2 X-axis table 3 Y-axis table 4 Workpiece 5 Work tank 6 Column 7 Z-axis head 8 Electrode 10 Bed 11 X-axis saddle 12 Y-axis saddle 21 Electrode weight detection sensor 24 Z-axis correction part 24a Weight measurement Means 24b First Z-axis error amount extraction means 24c First Z-axis error amount calculation means 24d Z-axis coordinate correction means 25 First servo control unit 23 Z-axis error amount data memory 30 Memory for each axis error data 31a Deflection characteristic selection means 31b Deflection characteristic calculation means 31c Second Z-axis error amount extraction means 31e Axis coordinate correction means

Claims (4)

[Claims] 1. During machining, a first Z-axis coordinate instructed based on a machining shape of a workpiece is set in a first servo section for controlling a Z-axis head and an XY axis table. , Said Z
While the electrode attached to the shaft head is moved toward and away from the work piece, a predetermined machining gap is created for the work piece in the machining tank into which the machining liquid has been injected to perform electric discharge machining. In a movable table type die-sinking electric discharge machine having a servo control means of No. 1, when an electrode is attached to the Z-axis head, when the weight of the electrode or the electrode is moved toward and away from a workpiece The displacement amount by which the Z-axis head is displaced by the reaction force is defined as a first Z-axis position error amount, and the first of the reaction force (hereinafter collectively referred to as a load) generated in the weight of the electrode to be mounted or in the gap.
Z-axis error amount data memory in which a plurality of Z-axis position error amounts are stored in correspondence with each other, and a gap when the weight attached to the Z-axis head or the electrode is moved toward and away from the workpiece. A reaction force generated on the Z-axis head as a load applied to the Z-axis head at predetermined time intervals and outputting the measured load as a measured load; and a first Z-axis error amount corresponding to the measured load, the Z-axis error amount. First Z-axis error amount extraction means for extracting and outputting from the data memory, and when the first Z-axis error amount is output, the first Z-axis set in the first servo control means. The axis coordinate is the first
And a Z-axis coordinate correcting unit that corrects the Z-axis error amount based on the Z-axis error amount. 2. When the first Z-axis error amount corresponding to the load is not extracted from the first Z-axis error amount extraction means, based on the measured load and the load of the Z-axis error amount data memory. A range of the measured load is obtained, a Z-axis error amount corresponding to the measured load is calculated from the range, and is output as the first Z-axis error amount to the Z-axis coordinate correction unit. The die-sinking electric discharge machine according to claim 1, further comprising: 3. During the machining, a relative axis coordinate commanded based on the machining shape of the workpiece is set in the second servo unit that relatively moves the X-axis saddle, the Y-axis saddle and the Z-axis head. Then, while the electrode attached to the Z-axis head is moved toward and away from the workpiece, a predetermined machining gap is created with respect to the workpiece in the machining tank into which the machining liquid has been injected, and electric discharge machining is performed. And a table fixed type die-sinking electric discharge machining apparatus having a second servo control means for machining the X-axis saddle and the Y-axis saddle by moving the relative axes relative to each other. The Y-axis saddle or X
When the axis saddle is moved relative to the second axis, the displacement amount of the Z-axis head due to the amount of deflection of the Y-axis saddle or the X-axis saddle is set to the second value.
Z-axis error amount, and a plurality of deflection characteristic data indicating the amount of movement of the Y-axis saddle or the X-axis saddle and the second Z-axis error amount are stored for each load (electrode weight or reaction force) of the Z-axis head. The memory for each axis error amount, the load measuring means for measuring the load applied to the Z-axis head at predetermined time intervals, the direction of the relative axis movement is read, and the corresponding direction is read by the load measuring means. Select the deflection characteristic data corresponding to the measured load from the memory for each axis error amount data,
Deflection characteristic selection means for notifying the selected deflection characteristic data, and the actual relative axis movement amount of the Y-axis saddle or X-axis saddle is read at predetermined time intervals, and the Y-axis saddle or X is selected from the selected deflection characteristic data. Second Z-axis error amount extraction means for extracting the second Z-axis error amount corresponding to the actual relative axis movement amount of the axis saddle; and when the second Z-axis error amount is extracted, The Z-axis set value of the relative movement axis set in the second servo control means is corrected on the basis of the second Z-axis error amount, and the second servo control means is corrected by the Z-axis correction value. A die-sinking electric discharge machining apparatus comprising: respective axis position correcting means for correcting the set values of the set Y-axis and X-axis. 4. When the flexure characteristic data is not selected by the flexure characteristic selecting means, the measured load and the relative movement axis coordinate are read, and the measured load is determined based on the load stored in the memory for each axis error data. And a flexure characteristic calculating means for obtaining a flexure characteristic data corresponding to a measured load from the range of the relative movement axis and outputting the flexure characteristic data to the second Z-axis error amount extracting means. The die-sinking electric discharge machine according to claim 3.