JPH0751946A - Temperature compensating device and method for diemilling electric discharge machine - Google Patents

Abstract

PURPOSE:To provide a diemilling electric discharge machine which is constituted to reduce the occurrence of the machining error of a work owing to the fluctua tion in temperature of machining liquid. CONSTITUTION:When machining is started at a step 101, the temperature of machining liquid is detected by a thermocouple temperature detector to read a detecting result in an NC device at a step 102. A displacement amount H of each axis taking temperature into consideration is calculated at a step 103 by a CPU according to a calculating formula stored at an RAM. The reference point of each axis is corrected at a step 104 according to the displacement amount H and machining of a work is continued at a stop 105. Every time a given time lapses, the steps 102-105 are executed again to correct the reference point of each axis. This constitution and method improve machining precision of a work.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature compensation device and method for a die-sinking EDM machine.

[0002]

2. Description of the Related Art The construction of a conventional die-sinking EDM machine is shown in FIGS.
Explained by. 4 to 6, 1 is an electrode having a predetermined shape for electric discharge machining, 1a is a workpiece to be machined by electric discharge machining, 1b is a table for mounting the workpiece 1a, and 1c is an insulating liquid. XY cross table in which the processing liquid 4 is immersed in the processing liquid, 4 is freely movable in the X-axis direction and the Y-axis direction by the X-axis motor 2 and the Y-axis motor 3, and the electrode 1 is detachable. And a vertical axis 7 which is equipped with a Z-axis motor 6 so as to be movable in the Z-axis direction, 7 is an XY-axis position detector for detecting the rotation amounts of the X-axis motor 2 and the Y-axis motor 3, and 8 is a Z-axis. Lifting shaft 5 by motor 6
Z-axis position detector that detects the amount of movement of the workpiece, 9 is a machining power supply that supplies the electrical energy required for electrical discharge machining between the electrode 1 and the workpiece, and 10 is an electrode exchange device that automatically exchanges the electrodes. is there.

An input device 12 for creating an NC program is, for example, a paper tape or a keyboard, and the XY cross table 4 and the elevating shaft 5 are automatically moved by the NC program. Reference numeral 14 is operation command means for receiving data from the input device 12 and instructing an operation to the axis movement control means 15 and the electrode exchange device control means 17 by the CPU 14a. Reference numeral 15 denotes the axis data from the operation command means 14 for the X-axis motor 2, Y. Position detecting means 17 for outputting to the axis motor 3 and Z axis motor 6 to detect the positions of the XY cross table 4 and the elevating shaft 5, and 17 controls the electrode exchanging device 10 based on the electrode exchanging instruction from the operation instructing means 14. Electrode exchange device control means 20, NC device including operation command means 14, axis movement control means 15, position detection means 16 and electrode exchange device control means 17, 33 stores setting data such as a machining reference point. RAM.

The operation of the die-sinking electric discharge machine configured as described above will be described. First, a processing reference point is set. The operator measures the dimensions of the workpiece 1a, sets the machining reference points X, Y, and Z with the input device 14 based on the measured dimension values, and stores them in the RAM 33. The reference points X, Y, and Z are set under the room temperature in which the die-sinking electric discharge machine is installed. Next, the electrode 1 is centered and the misalignment amount within the allowable value is similarly stored in the RAM 33.

First, the workpiece 1a is placed on the table 1c, and the machining liquid is poured to a predetermined height of the workpiece 1a. Next, the processing amounts of the X, Y, and Z axes of the workpiece 1a are input by the input device 14 for each roughing and finishing, and the RAM 33 is input.
Remember. The electrode exchanging device control unit 17 operates the electrode exchanging device 10 to select the electrode 1 for rough machining, and the rough machining of the workpiece 1a is started by the electrode 1 based on the preset reference position coordinates. During rough machining, the X-axis and Y-axis of the workpiece 1a are moved by the X-axis motor 2 and the Y-axis motor 3 to X-axis.
The Y cross table 4 is operated for machining, and the Z axis is moved by the Z axis motor so that the machining of the workpiece 1a matches the set value by the X, Y, Z axis scales 7a, 7b, 8 The desired processing is performed while performing feedback control while measuring. When the rough machining is completed, the electrode exchanging device control means 17 operates the electrode exchanging device 10 to select the finishing electrode 1 to perform the finishing process. In this procedure, the work piece 1 is replaced by replacing the electrode 1 for roughing with the electrode 1 for finishing.
After processing a, a series of processing steps ends.

This machining process requires a long time, and the machining depth of the workpiece 1a is set by the temperature rise of the machining liquid due to the discharge of the workpiece 1a from the electrode 1 and the expansion of the workpiece 1a. Fluctuates against. Therefore, the die-sinking electric discharge machine is used in a constant temperature room to keep the room temperature constant and maintain the temperature of the working fluid.

However, since the equipment for the temperature-controlled room is large and expensive, it may not be possible to process in a temperature-controlled environment. In such a case, accurate machining is difficult because the workpiece 1a contracts and expands due to temperature fluctuations. Therefore, in order to solve the above-mentioned problems, JP-A-2-
In 298456, in order to compensate the temperature of the machine tool, a method is proposed in which the relationship between the ambient temperature and the dimension of the workpiece 1a is obtained by an experiment, and a predetermined functional expression is determined from the experimental result to try to compensate the temperature. .

However, since the ambient temperature and the dimensions of the workpiece 1a are experimentally determined, the coefficient of linear thermal expansion differs when the material of the workpiece changes. Therefore, it is complicated because it requires an experiment depending on the kind of material of the workpiece 1a. Further, such a proposal does not take into consideration the peculiarities of the die-sinking EDM machine because the general purpose is to compensate the temperature of machine tools. That is, the dimension of the workpiece 1a is measured in the machining chamber, a machining reference point is set, and the workpiece 1a is electric discharge machined in the machining fluid.
Contracts and expands due to temperature fluctuations in the working fluid. Therefore, the processing reference point itself fluctuates and the workpiece 1a cannot be processed accurately.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a die-sinking EDM machine which is not easily affected by ambient temperature without using a temperature-controlled room.

Another object of the present invention is to provide a die-sinking EDM machine capable of compensating for temperature without performing an experiment each time the material of the workpiece is changed.

Further, another object of the present invention is to provide a die-sinking electric discharge machine which can improve the processing accuracy of the work piece due to the temperature fluctuation of the working liquid.

[0012]

According to a first aspect of the present invention, there is provided a temperature compensating device for a die-sinking EDM machine, which discharges the workpiece by causing an electric discharge between the workpiece and an electrode in a machining tank filled with a machining fluid. In a die-sinking electric discharge machine for machining, the temperature detection means for detecting the temperature of the machining liquid, the linear expansion coefficient of the work piece, and the displacement amount equation determined by the temperature detected by the temperature detection means are used to calculate the object to be processed. This is to change the machining command of the workpiece.

A method for compensating a temperature of a die-sinking electric discharge machine according to a second aspect of the invention is a die-sinking electric discharge machining for machining the workpiece by causing an electric discharge between a workpiece and an electrode in a machining tank filled with a machining liquid. In the machine, the temperature of the working fluid is detected by the temperature detecting means, and the displacement amount is calculated by a formula determined by the linear expansion coefficient of the work piece and the temperature detected by the temperature detecting means, and a machining command for the work piece is issued. Is to change.

According to a third aspect of the present invention, there is provided a temperature compensating device for a die-sinking EDM machine, wherein an electric discharge is performed between the workpiece and an electrode in a machining tank filled with a machining fluid to machine the workpiece. In the machine, temperature detecting means for detecting the temperature of the working fluid, time measuring means for measuring the time from the immersion of the working fluid in the workpiece to the processing time point, the coefficient of linear expansion of the workpiece and the temperature The displacement amount is calculated by the formula of the transient state of the displacement amount determined by the temperature detected by the detection unit and the time measured by the time measurement unit, and the machining command of the workpiece is changed.

According to a fourth aspect of the present invention, there is provided a temperature compensating device for a die-sinking EDM machine, wherein an electric discharge is performed between the workpiece and an electrode in a machining tank filled with a machining fluid to machine the workpiece. In the machine, temperature detection means for detecting the temperature of the working fluid, a linear expansion coefficient of the work fluid, and the displacement amount determined by the temperature of the working fluid detected by the temperature detection means It is provided with means for changing the machining command and temperature compensating means for compensating the temperature of the machining fluid detected by the temperature detecting means only during the finishing of the workpiece.

[0016]

According to the temperature compensating apparatus and method of the present invention, the temperature of the working fluid is detected by the temperature detecting means, and the linear expansion coefficient of the work piece and the temperature detected by the temperature detecting means are used to calculate the temperature. Calculate the amount of displacement and change the machining command.

According to the temperature compensating device of the third aspect, the temperature of the working fluid is detected by the temperature detecting means, and the time after the working fluid is dipped in the work piece is measured by the time measuring means to measure the line of the work piece. The displacement amount is calculated by the formula of the transient state of the displacement amount determined by the expansion coefficient, the temperature detected by the temperature detecting means, and the time measured by the time measuring means, and the machining command of the workpiece is changed.

According to the temperature compensating device of the fourth aspect, the temperature of the machining fluid is detected by the temperature detecting means only during the electric discharge machining of the workpiece by the finishing machining, and the linear expansion coefficient of the workpiece and the temperature detecting means are detected. The displacement amount is calculated by a formula determined by the temperature and the machining command is changed.

[0019]

【Example】

Example 1. The present invention will be described below based on embodiments shown in the drawings. In the figure, the same reference numerals as those used in the related art indicate the same or corresponding parts. In FIG. 1, 31 is a thermocouple temperature detector which is a temperature detecting means for detecting the temperature of the machining liquid in the machining tank, and 32 is a thermocouple temperature detector 31 which indicates a temperature value N which is a detection signal.
The input interface 33a for inputting to the C device 20 is a difference between the temperature T (° C) obtained by the thermocouple temperature detector 32 and the initial temperature T ₀ (° C) depending on the temperature change value ΔT (° C). It is a RAM for storing the following formulas of the axial displacement amounts H _X , H _Y , H _Z (μm). _{H X = △ TN 2 L 2X} , H Y = △ TN 2 L 2Y, H Z = △ T
(N ₁ L _1Z + N ₂ L _2Z ) N ₁ : _Linear expansion coefficient of table 1b (μm / ° C) N ₂ : Linear expansion coefficient of workpiece 1a (μm / ° C) L _1Z : Z axis of table 1b Length (μm) L _2X : Length of workpiece 1a in X-axis direction (μm) L _2Y : Length of workpiece 1a in Y-axis direction (μm) L _2Z : Z of workpiece 1a Axial length (μm)

The operation of the die-sinking electric discharge machine configured as described above will be described with reference to the flow chart shown in FIG. First, a processing reference point is set. The worker is the workpiece 1a
Of the machining point, and based on the measured dimension value, a processing reference point X,
Y and Z are set by the input device 14 and stored in the RAM 33. The reference points X, Y, and Z are set under the room temperature in which the die-sinking electric discharge machine is installed. Next, electrode 1
Centering is performed and the misalignment amount within the allowable value is also stored in the RAM.
Store in 33. Further, the operator sets the linear expansion coefficients N ₁ and N ₂ and the length L _{1Z of the} table 1b in the Z-axis direction and the lengths L _2X , L _2Y and L _2Z of the workpiece 1a in the X, Y and Z axes directions. Each is input by the input device 14 and stored in the RAM 33a.
Next, the workpiece 1a is placed on the table 1c, the machining liquid is poured to a predetermined height of the workpiece 1a, and the machining amounts of the X, Y, and Z axes of the workpiece 1a are set for each rough machining and finishing machining. It is input by the input device 14 and stored in the RAM 33.

Next, when the operator presses the processing start button, it is determined that the processing is started (step 101), and if the processing start button is not pressed, the processing start determination is continued (step 101). When it is determined that the machining is started, the electrode exchanging device control means 17 operates the electrode exchanging device 10 to select the electrode 1 for rough machining, and the workpiece 1a is operated by the electrode 1 based on preset reference position coordinates. Rough machining is started with the target machining amount. The temperature detection value of the working fluid is input by the thermocouple temperature detector 32 through the input interface 32.
C is read into the device 20 (step 102), the displacement amount H
_X , H _Y , H _Z are calculated by the above-mentioned formula stored in advance in the RAM 33a by the CPU 34 (step 10).
3) Then, the reference points of the X, Y, and Z axes are corrected according to the displacement amounts H _X , H _Y , and H _Z (step 104), and rough machining of the workpiece 1a is continued (step 105). It is confirmed whether a predetermined time has passed (step 106), and if the predetermined time has passed, steps 102 to 105 are executed again. On the other hand, if the predetermined time has not elapsed, the thermocouple temperature detector 32 does not update the temperature detection of the machining fluid, so that the machining is continued based on the current temperature detection value. Next, the workpiece 1a
When the X, Y and Z axes of No. reach the finishing machining amount set by the input device 14, it is judged that the machining is finished, but since the machining amount has not yet been reached because it is at the stage of rough machining, the judgment of the machining end is continued. (Step 107).

X, Y, Z preset by roughing
When the machining amount of the shaft is reached, the electrode exchanging device control means 17 operates the electrode exchanging device 10 to select the electrode 1 for finishing, and the workpiece 1a is started by the electrode 1 with the set machining amount as a target. . The temperature detection value of the working fluid is read by the thermocouple temperature detector 32 into the NC device 20 through the input interface 32 (step 102),
The displacement amounts H _X , H _Y , and H _Z are stored in the RAM 33 by the CPU 34.
allowed calculated by prestored above formula to a (step 103), the displacement amount H _X, H _Y, X according to H _Z, Y, Z
The reference point of the axis is corrected (step 104), and the workpiece 1a
The finishing process is started (step 105). It is confirmed whether a predetermined time has passed (step 106), and if the predetermined time has passed, the above steps 102 to 105 are executed. On the other hand, if the predetermined time has not elapsed, the thermocouple temperature detector 3
Since the temperature detection of the machining fluid is not updated by No. 2, machining is continued based on the current temperature detection value. Next, when the X, Y, and Z axes of the workpiece 1a do not reach the finishing machining amount set by the input device 14, the determination of machining completion is continued (step 107). On the other hand, when the processing amount is reached, it is determined that the processing is completed (step 107), and the series of processing steps is completed.

Example 2. Currently, it is necessary to perform the setup work after inserting the workpiece 1a into the machining tank and pouring the machining liquid into the machining tank.
Since it takes a long time, in Example 1, the displacement amounts H _X , H _Y , and H _Z of the respective axes were obtained assuming that the workpiece 1a sufficiently follows the temperature of the machining liquid. However, if the setup work is shortened due to future technological progress, the work piece 1
The temperatures of a and the working liquid are not the same. That is, the temperature of the workpiece 1a follows the temperature of the machining liquid with a predetermined delay. It is necessary to obtain the axial displacement amounts H _X t, H _Y t, and H _Z t of the workpiece 1a in the transient state and correct the reference point.

Therefore, the temperature compensator for the die-sinking EDM machine of the second embodiment is almost the same as that of the first embodiment except for the following points. The difference between the temperature T determined by the thermocouple temperature detector 32 and the initial temperature T ₀ (° C) is calculated by the temperature change value ΔT (° C) for each axial displacement amount H _X t, H _Y t, H _Z t ( μm) consisting of a RAM 33a for storing the following formula, and a pressure detector (not shown)
Is configured to generate a signal when the processing tank 1b is filled with the processing liquid and the pressure at the bottom of the processing tank 1b exceeds a predetermined value. _{H X t = H X (1} -ε -At), H Y t = H Y (1-ε -At), H Z t
= H _Z (1-ε- ^At ) t: Time from the time when the work piece is immersed in the working fluid to the working time (SEC) A: The thermal time constant of the work piece 1a, which is 1 / CR (SEC) Where C is the heat capacity of the work piece 1a (J / ° C) R is the heat resistance of the work piece 1a (° C / W)

The operation of the die-sinking electric discharge machine configured as described above will be described with reference to the flow chart shown in FIG. When this flow chart is executed, the time measuring means is executed. The operation is almost the same as that of the first embodiment except for the following points. It is judged whether or not the setup work before the electric discharge machining is completed (step 100a), and the completion of the setup work is determined by a pressure detector (not shown) when the machining tank 1b is filled with the machining liquid. A signal is generated, the signal is taken into the NC device 20 through the input interface 32, the CPU 34 judges that the setup work is completed, and if it is completed, the measurement of the time t is started (step 100b), and the displacement is started. The quantities H _X t, H _Y t and H _Z t are calculated by the CPU 34 according to the above formula stored in the RAM 33a (step 103).

Example 3. In the first embodiment, the temperature of the machining liquid is detected and the machining reference point is corrected without making a distinction between the rough machining and the finishing machining to improve the machining accuracy. However, the final processing shape of the workpiece 1a is determined by the finishing process. Therefore, the accuracy of the final machining shape can be secured by detecting the temperature of the machining fluid and correcting the machining reference point only during the finishing machining. Therefore, the configuration according to the third embodiment in which only the finishing process is temperature-compensated is substantially the same as that of the first embodiment except for the following points. The displacement amount of each axis of the RAM 33a is calculated only when the finishing process is selected by the electrode exchange device control means 17. The operation of the third embodiment configured as above will be described below. The temperature compensating means is executed when the following flowchart is executed. It is judged whether the finishing process is selected by the electrode exchanging device control means 17 (step 101, not shown), and if the finishing process is selected, steps 102 to 1 shown in FIG.
07 is executed to finish the machining.

[0027]

According to the first and second aspects of the present invention, there is an effect that it is possible to obtain a die-sinking electric discharge machine capable of improving the processing accuracy of the work piece due to the temperature fluctuation of the working liquid.

Further, according to the first and second aspects of the invention, there is an effect that a die-sinking electric discharge machine can be provided which can perform temperature compensation without performing an experiment each time the material of the workpiece is changed.

According to the third aspect of the invention, the work piece 1
Even if the temperature of a does not sufficiently follow the temperature of the machining fluid, it is possible to obtain the die-sinking electric discharge machine that can improve the machining accuracy of the workpiece due to the temperature variation of the machining fluid.

According to the invention described in claim 4, the same effect as that of the invention described in claims 1 and 2 can be obtained without setting the machining amounts of the X, Y and Z axes by rough machining.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a die-sinking electric discharge machine according to the present invention.

FIG. 2 is a flowchart showing the operation of the electric discharge machine according to the present invention.

FIG. 3 is a flowchart showing the operation of the electric discharge machine according to the present invention.

FIG. 4 is an overall configuration diagram of a conventional die-sinking electric discharge machine.

FIG. 5 is a perspective view of the entire die-sinking electric discharge machine.

FIG. 6 is a sectional view taken along line VV of FIG.

[Explanation of symbols]

 1 Electrode 1a Workpiece 1b Processing tank 31 Temperature detector

Claims (4)

[Claims] 1. A die sinking electric discharge machine for machining a workpiece by causing an electric discharge between the workpiece and an electrode in a machining tank filled with the machining fluid, and a temperature detecting means for detecting the temperature of the machining fluid. And a means for changing a machining command of the workpiece based on a formula of a displacement amount determined by the linear expansion coefficient of the workpiece and the temperature of the machining liquid detected by the temperature detecting means. Temperature compensation device for die-sinking EDM. 2. In a die-sinking electric discharge machine for machining the workpiece by causing an electric discharge between the workpiece and an electrode in a machining tank filled with the machining fluid, the temperature detecting means detects the temperature of the machining fluid. Then, the displacement amount is calculated by a formula determined by the coefficient of linear expansion of the workpiece and the temperature of the working fluid detected by the temperature detecting means, and the machining command of the workpiece is changed. Temperature compensation method for processing machines. 3. A die-sinker EDM machine for machining a workpiece by causing an electric discharge between the workpiece and an electrode in a machining tank filled with the machining fluid, and a temperature detecting means for detecting the temperature of the machining fluid. The time measuring means for measuring the time from the immersion of the machining liquid in the workpiece to the processing time point, the linear expansion coefficient of the workpiece, the temperature detected by the temperature detecting means, and the time measuring means were measured. A temperature compensating device for a die-sinking EDM machine, comprising means for calculating a displacement amount by a formula of a transient state of the displacement amount determined by time, and changing the machining command of the workpiece. 4. A die sinking electric discharge machine for machining the workpiece by causing an electric discharge between the workpiece and an electrode in a machining tank filled with the machining fluid, and a temperature detecting means for detecting the temperature of the machining fluid. And a means for changing the machining command of the workpiece based on a linear expansion coefficient of the workpiece and a displacement amount formula determined by the temperature of the machining fluid detected by the temperature detecting means,
A temperature compensating device for a die-sinking electric discharge machine, comprising temperature compensating means for compensating for the temperature of the machining liquid detected by the temperature detecting means only during finishing of the workpiece.