JP4463901B2 - Electric discharge machining method and apparatus - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to an electric discharge machining method and apparatus for supplying a machining fluid to a machining gap and discharging the workpiece with an electrode to perform electric discharge machining on a workpiece.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an electric discharge machining method is known in which a machining fluid is supplied to a machining gap between an electrode and a workpiece, and the workpiece is discharged by electric discharge at the electrode. In this electrical discharge machining method, for example, when finishing a small amount of follow-up machining on a pre-machined surface to finish with high precision, the positional relationship between the electrode to be discharged and the workpiece is clearly grasped, and the amount of follow-up machining is It is necessary to calculate accurately. Conventionally, in order to determine the machining amount by electric discharge machining, a method for sensing by contacting the reference surface of the workpiece before electric discharge machining, or as disclosed in Japanese Patent No. 2559789, the discharge gap is a specific value. For example, a method is known in which discharge is performed for several tens of seconds until the starting point is reached, the origin of machining is positioned, and the electrode is moved to the machining portion to perform electric discharge machining.
[0003]
[Problems to be solved by the invention]
However, the touch detection method generates a touch detection error, and the discharge discharge method causes an error due to the fluctuation range of the discharge gap (described as measurement error ± 2 μ). To do. Further, in Japanese Patent No. 2559789, in order to discharge the processed portion for several tens of seconds until the discharge gap reaches a specific value in the same manner as described above in order to detect an error from the target value after the processed portion is subjected to electric discharge machining, Measurement errors due to the fluctuation range of the discharge gap twice are accumulated. This adversely affects processing accuracy.
[0004]
In addition, if discharge is performed for several tens of seconds under the discharge conditions used for machining, the machining progress caused by the discharge exceeds a negligible amount. Therefore, the discharge to be performed for the origin position needs to be performed under a weak special condition in which the machining progress is small. Therefore, it takes several tens of seconds (according to the description, 20 to 60 seconds) until the discharge gap converges to a specific value. Therefore, the origin position cannot be quickly determined.
[0005]
Moreover, when the shape of the electrode is an irregular shape such as a taper shape or a curved surface shape other than the flat surface shape, measurement cannot be performed by directly contacting the taper surface of the electrode with the flat surface of the workpiece. .
[0006]
FIG. 9 is a diagram for explaining a conventional method for determining the origin position of machining.
[0007]
For example, when the electrode 100 has a shape having a tapered portion at the tip as shown in the same figure, a flat surface 100a is provided at an appropriate position of the electrode 100 as shown in FIG. In other words, the reference surface 101a of the workpiece 101 is discharged for several tens of seconds.
[0008]
Therefore, the distance in the Z direction (machining direction) from the temporary reference surface (flat surface 100a) of the electrode 100 to the tip portion must be measured and the machining amount must be calculated in consideration of this, and the discharge work becomes complicated. In addition, since it is necessary to provide the flat surface 100a at an appropriate position of the electrode 100, there is a problem that it takes time for designing and is disadvantageous in terms of cost.
[0009]
Further, the discharge gap varies depending on the machining area and the shape of the surface to be machined, and these are factors that cause a measurement error of the discharge gap.
[0010]
For example, as shown in FIG. 5A, in the method of measuring with the reference surface 101a of the workpiece 101 and the tip of the electrode 100, the workpiece surface is flat and the processing area is small. On the other hand, as shown in FIG. 5B, when the measurement is performed with the workpiece 101b of the workpiece 101 and the tapered surface of the electrode 100, the workpiece 101b is curved and has a large machining area. Therefore, the discharge gap is different between the case of FIG. 9A and the case of FIG.
[0011]
Further, as shown in FIG. 6C, even when the processing area is set to be equal to that in FIG. 6B, the difference in the discharge gap occurs because the shape of the processed part is different.
[0012]
FIG. 10 is a diagram showing the relationship between the processing area and the discharge gap. As shown in the figure, it can be seen that the discharge gap differs depending on the processing area.
[0013]
FIG. 11 is a diagram showing the relationship between the concentration of powder mixed in the machining fluid and the discharge gap. As shown in the figure, the discharge gap also differs depending on the powder mixing concentration.
[0014]
As described above, a difference occurs in the discharge gap due to the difference in the processing area, the shape of the surface to be processed, and the difference in the powder mixing concentration. Therefore, in the conventional method of discharging until the discharge gap reaches a specific value, the influence of the error cannot be avoided even if the discharge gap of the specific value is obtained, and there is a problem in accuracy. In other words, the discharge gap measured in advance is not reproduced when actually processed, and the difference appears as a measurement error. Unless this is taken into account, high processing accuracy cannot be obtained.
[0015]
Conventionally, due to the above problems, for example, it is difficult to obtain a desired size by performing a small amount of follow-up correction processing of about several μm to several tens of μm from the surface finished by pre-processing, for example. It was. When such a small amount of processing is required, for example, when a mold once produced is trial-tested, a molded product with a desired size and shape cannot be obtained due to deformation or displacement of the resin, This is a case where it is desired to correct the finished mold part by several μm to several tens of μm, for example, when a modification is required when the dimensions are changed.
[0016]
Conventionally, when such processing is performed, a skilled worker performs a small amount of processing, measures the dimensions with a dial gauge, a microscope, or the like, and carefully processes the shortage again. However, not only failure such as excessive removal occurred, but complicated work by repeated measurement and processing was required, automation was difficult, and efficiency was remarkably bad.
[0017]
As described above, in the conventional electric discharge machining method, high-precision machining is difficult due to an error due to the fluctuation width of the discharge gap, and high-precision machining is not easy because it requires skill, There is a problem that complicated and inefficient work for measurement and processing is required.
[0018]
The present invention has been made to solve the above-described problems of the prior art, and its purpose is to provide an electric discharge machining method capable of efficiently and accurately performing a small amount of follow-up machining without requiring skilled or troublesome work, and To provide an apparatus.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, an electric discharge machining method according to claim 1 of the present invention is an electric discharge machine that supplies a machining liquid to a machining gap between an electrode and a workpiece and discharges the workpiece by the electric discharge at the electrode. in the processing method, the actual measurement step of measuring the machining thrust amount to provide against the processed surface of the workpiece, is moved toward the working direction in front Symbol electrodes to the treated surface of the workpiece, the An acquisition step of acquiring the current position of the electrode when 3 seconds or more and 20 seconds or less have elapsed since the start of discharge of the electrode, and an actual measurement by the measurement step at the current position of the electrode acquired by the acquisition step a value obtained by adding the machining thrust amount is set as the final position the electrodes to be reached, and a processing step of performing a final position until in discharge electrostatic processing and the setting, in said acquiring step and the processing step, Flip and in electrical conditions and performing discharge under the same electrodes.
[0030]
In order to achieve the same object, an electric discharge machining apparatus according to claim 4 of the present invention supplies a machining liquid to a machining gap between an electrode and a workpiece, and discharges the workpiece by performing an electric discharge machining on the workpiece. in the processing device, the actual measurement means for measuring the machining thrust amount to provide against the processed surface of the workpiece, is moved toward the working direction in front Symbol electrodes to the treated surface of the workpiece, the An acquisition means for acquiring the current position of the electrode when 3 seconds or more and 20 seconds or less have elapsed since the start of discharge of the electrode, and an actual measurement by the actual measurement means at the current position of the electrode acquired by the acquisition means a value obtained by adding the machining thrust amount is set as the final position the electrodes to be reached, and a processing means for performing a final position until in discharge electrostatic processing and the setting, and the processing means and the obtaining means, same And performing discharge and at the same electrode in electrical conditions.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0035]
(First embodiment)
FIG. 1 is a block diagram showing a configuration of an electric discharge machining apparatus according to the first embodiment of the present invention.
[0036]
This apparatus includes an automatic control device 11 (machining control means). The automatic control device 11 is a computer numerical control device (hereinafter referred to as “NC device 12”) (current position storage unit (means), gap value storage unit ( Means), drive amount storage means, current position storage means), power supply control device 13, discharge circuit 14, discharge detection means 15, and controller device 16 (drive amount acquisition means).
[0037]
A workpiece 3 is fixed on the processing table 4. The X-axis direction driving device 5 and the Y-axis direction driving device 7 move the processing table 4 in the X / Y direction orthogonal to each other on the horizontal plane based on an instruction from the NC device 12. The X-axis direction position detection device 6 and the Y-axis direction position detection device 8 detect the operation position of the machining table 4 and send the signal to the NC device 12.
[0038]
The machining head 1 is configured such that an electric discharge machining electrode 2 is detachable at the lower end. Although not shown, this apparatus is configured so that the electrode 2 can be automatically replaced with another electrode by an automatic hand.
[0039]
The Z-axis direction drive device 9 moves the machining head 1 in the vertical direction, that is, in the Z direction (up and down direction in the figure) based on an instruction from the NC device 12. The Z-axis direction position detection device 10 (current position acquisition means) detects the operating position of the machining head 1 and sends the signal to the NC device 12.
[0040]
The workpiece 3 is disposed in the processing tank 18. At the time of electric discharge machining, the machining liquid 17 mixed with powder for electric discharge machining is stored in the machining tank 18. As the powder, for example, ferrous and non-ferrous metal powders such as chromium, aluminum, and semiconductor are preferable.
[0041]
As described above, the NC device 12 transmits drive signals to the X-axis direction drive device 5, the Y-axis direction drive device 7, and the Z-axis direction drive device 9, and the X-axis direction position detection device 6 and the Y-axis direction position detection. Each position information of the machining head 1 and the machining table 4 obtained by receiving each detection signal from the apparatus 8 and the Z-axis direction position detection apparatus 10 is written in the memory unit M. The memory unit M includes M1, M2, and M3.
[0042]
The NC device 12 includes information (for example, a minute machining follow-up amount, electrical conditions, machining order, etc.) that is input and set in advance by the controller device 16 and stored in the memory unit M, and a control program (machining operation, feed amount). Drive signals are supplied to the X-axis, Y-axis, and Z-axis direction drive devices 5, 7, and 9 in accordance with the setting of the machining direction, electrical conditions, and the like. A voltage output signal is applied to the power supply control device 13 and the discharge circuit 14 so that a desired discharge voltage is applied to the power supply control device 13. As the minute machining follow-up amount, a value grasped in advance by actual measurement or the like is input. The discharge detection means 15 detects the discharge of the electrode 2 and sends the detection signal to the NC device 12.
[0043]
FIG. 2 is a diagram showing a flowchart of the procedure of the minute electric discharge machining in the present embodiment. FIG. 3 is a schematic diagram showing a machining situation corresponding to FIG. Hereinafter, a description will be given with reference to FIGS.
[0044]
This processing is so-called sculpture electric discharge machining, and the processed surface 3A of the workpiece 3 is a pre-processed portion by pre-processing as shown in FIG. Before starting the apparatus, in the NC apparatus 12, the first position information (X1, Y1, X1) indicating the distance from the origin (X0, Y0, Z0) determined for the workpiece 3 to the target depth of the processing surface 3A. Z1) is stored in the memory area M1. It is efficient to set the machining start point at a position about 1 mm above the first position information (X1, Y1, Z1).
[0045]
Next, the machining liquid 17 in which the powder for electric discharge machining is mixed in the machining tank 18 is filled, and the operation is started. First, the electrode 2 used in this processing is exchanged (ATC exchange) (step S201 in FIG. 2), and the electrode 2 is moved to the machining position, that is, above the processing surface 3A (step S202).
[0046]
Next, a discharge voltage according to the conditions (predetermined conditions) of the powder final finishing stage is applied from the power supply control device 13 to the electrode 2 via the discharge circuit 14, and the Z-axis direction driving device 9 is driven in this state to cover the electrode 2. The processing surface 3A is lowered from above. This is discharge measurement (step S203). Then, when the discharge is performed for a predetermined time (for example, 3 seconds), the processing head 1 is stopped, and the position information (X2, Y2, Z2) of the processing head 1 at that time is used as second position information (processing point of the electrode 2). (Step S204). At this time, a discharge gap A (gap value) is generated between the electrode 2 and the processing surface 3A (FIG. 3B). This second position information indicates the current position in the Z direction of the machining head 1 to the electrode 2.
[0047]
Next, minute processing thrust amount which is previously inputted set in the controller device 16 (which was stored in the memory unit M) is added to the second position information stored in the memory area M2, the aim depth of the new machining The third position information (X3, Y3, Z3) (target depth machining point) is stored in the memory area M3 as the position (step S205) (FIG. 3C). The addition operation is performed by the controller device 16.
[0048]
Next, based on the third position information (X3, Y3, Z3) stored in the memory area M3, electric discharge machining is performed to the end under exactly the same conditions as used in the electric discharge measurement in step S203 (step S206). (FIG. 3 (d)). That is, the final machining is performed with the same electrode 2 under the same machining area, the same conditions (electrical conditions), and the same machining liquid state by the discharge voltage in the final powder finishing stage. In addition, wear and thermal displacement are unlikely to occur due to minute processing. As a result, the discharge gap A ′ substantially the same as the discharge gap A in the case of FIG. 3B is reproduced, and the cause of the error is eliminated.
[0049]
After finishing the processing (step S207), the controller device 16 issues an instruction and moves to the next processing portion to perform the same processing, or exchanges with another electrode 2 and shifts to a different processing portion.
[0050]
FIG. 4 is a diagram showing a test result of the reproducibility of the discharge gap by powder electric discharge machining. This figure shows the discharge gap at the machining location when the same electrode is repeatedly discharged for 3 seconds at the same machining location.
[0051]
According to the figure, it can be seen that the error of the discharge gap is reduced to about 1 μm even after 7 repetitions. Although not shown in the figure, since the eighth time, the progress of processing due to repeated processing of the same portion has been observed. From this fact, in order to maintain the machining accuracy, it can be said that the discharge measurement is suitably about 3 seconds, which is sufficiently shorter than the time corresponding to 3 seconds × 7 times. It is not considered. Note that it may be shorter than 3 seconds. For example, if it is set as short as possible as long as there is no problem of erroneous detection of the presence or absence of discharge, the efficiency is improved and the progress of processing is further reduced.
[0052]
Moreover, the reproducibility of the discharge gap is better when the powder is mixed than when the powder is not mixed. This is presumably because the discharge gap is about twice as large in the case of the powder-mixed machining liquid, and the discharge gap is stabilized due to the good removal of the machining waste.
[0053]
According to the present embodiment, the current position of the electrode 2 is grasped by discharge measurement according to the conditions of the final powder finishing stage, and the target depth position of the final machining is determined by adding the minute machining follow-up amount grasped in advance to this. Since it was set and processed to the final stage under the conditions of the final powder finishing stage, the discharge gap A when grasping the current position of the electrode 2 and the discharge gap A ′ when the final finishing was completed are matched within a very small error range. Can be made. Therefore, even if the value of the discharge gap itself is unknown, the final processing position is determined from the relative positional relationship starting from the current position of the electrode 2 at the time of discharge measurement, so there is no need to confirm the measurement again. It eliminates errors caused by various factors and enables highly accurate micro discharge machining. Moreover, the occurrence of mistakes by humans is small, and it is possible to easily cope with irregularly shaped workpiece surfaces. Therefore, a small amount of follow-up processing can be performed efficiently and accurately without requiring skill or troublesome work.
[0054]
In addition, the memory unit M and controller device 16 are provided to store and calculate various data such as the current position of the electrode 2 by discharge measurement and the target depth of final machining. Can be done well.
[0055]
It should be noted that the conditions (predetermined conditions) of the final powder finishing stage and the time of discharge measurement per time are conditions and times such that the variation in the discharge gap A is sufficiently small with respect to the target finishing accuracy of the surface to be processed. Should be set.
[0056]
(Second Embodiment)
In the first embodiment, the amount of minute machining is grasped in advance, and the final machining position is set by using the current position of the electrode 2 at the time of discharge measurement as a clue. In the second embodiment, the powder The discharge gap A under the condition of the final finishing stage is grasped in advance, and the minute machining drive-in amount is calculated from this and the current position of the electrode 2 at the time of discharge measurement. Therefore, the configuration of the present embodiment is the same as that of the first embodiment (FIG. 1), but the discharge gap A is measured in advance when the discharge is performed under the same conditions as those in the final powder finishing stage. This is different from the first embodiment in that it is stored in the part M and a minute machining follow-up amount is calculated after the discharge measurement.
[0057]
FIG. 5 is a diagram showing a flowchart of the procedure of the minute electric discharge machining in the present embodiment. FIG. 6 is a schematic diagram showing a machining state corresponding to FIG. Hereinafter, a description will be given with reference to FIGS. 5 and 6.
[0058]
In this embodiment, as shown in FIG. 6A, the workpiece 3 is processed from a state where there is no processed surface. The conditions of the working fluid are the same as in the first embodiment.
[0059]
First, the electrode 2 is moved to the processing position, that is, above the processing surface 3A (step S501 in FIG. 5). Then, the processing target depth is set to be shallower than the finished dimension (several μ to 10 μ), and processing is performed under conditions for rough processing, that is, high output current (step S502) (FIG. 6B).
[0060]
Next, the discharge measurement is performed at the discharge voltage in the final powder finishing stage in exactly the same manner as in step S203 of FIG. 2 (step S503). Then, the current position of the electrode 2 is detected, and based on the detected current position of the electrode 2 and the discharge gap A that has been grasped and stored in advance, the shortage to the target value, that is, the necessary amount of minute machining is determined. Calculate (step S504) (FIG. 6C).
[0061]
Next, it is determined whether or not the calculated minute machining follow-up amount is equal to or greater than a predetermined amount (for example, 3 μ) (step S505). Finish processing. On the other hand, if the calculated minute machining follow-up amount is greater than or equal to the predetermined amount, it is not sufficient, so the calculated minute machining follow-up amount, that is, the machining error is added to the current position of the electrode 2 to calculate a new machining position ( Step S506) (FIG. 6D).
[0062]
Next, electric discharge machining is performed up to the calculated new machining position under the same powder final finishing conditions as those used in the electric discharge measurement in step S503 (step S507) (FIG. 6 (e)), and the machining is completed. (Step S508).
[0063]
According to the present embodiment, if the discharge gap under a predetermined condition is known, the minute machining follow-up amount is calculated from this and the current position of the electrode 2 at the time of discharge measurement. The error due to the consumption amount of 2 can be canceled, and there is no adverse effect of accumulated error due to many discharge measurements. Therefore, the same effects as those of the first embodiment can be obtained.
[0064]
In addition, even if the workpiece 3 is unprocessed, the processing position up to the final finishing can be accurately obtained and processed, so that smooth automatic processing can be performed.
[0065]
In addition, since the pre-processing for electric discharge measurement can be performed under high-efficiency conditions, even if the processing cost is large, the processing efficiency in the pre-processing is not deteriorated.
[0066]
This embodiment is particularly useful when the thermal displacement of the workpiece 3 is small, and is suitable for a workpiece with a short machining time.
[0067]
(Third embodiment)
In the first embodiment, the amount of minute machining driven when a minute amount is machined on an already machined surface is grasped in advance, and the final machining position is set based on the current position of the electrode 2 at the time of discharge measurement. However, in the third embodiment, when a minute amount is processed through rough machining on an unmachined surface, the amount of minute machining driven-in is measured after the deformation or displacement due to the processing heat of the workpiece disappears. The final machining position is set using this and the current position of the electrode 2 at the time of discharge measurement as a clue. Therefore, the configuration is the same as that of the first embodiment (FIG. 1).
[0068]
FIG. 7 is a diagram showing a flowchart of the procedure of the small amount electric discharge machining in the present embodiment. FIG. 8 is a schematic diagram showing a machining situation corresponding to FIG. Hereinafter, a description will be given with reference to FIGS.
[0069]
In the present embodiment, as shown in FIG. 8A, the workpiece 3 is processed from a state where there is no processed surface. The conditions of the working fluid are the same as in the first embodiment.
[0070]
First, the electrode 2 is moved to the processing position, that is, above the processing surface 3A (step S701 in FIG. 7). Then, the processing target depth is set to be shallower than the finished dimension (several μ to 10 μ), and processing is performed under conditions for rough processing, that is, high output current (step S702) (FIG. 8B).
[0071]
Next, after a sufficient time has elapsed for the thermal deformation and thermal displacement of the workpiece 3 to disappear (for example, the next day), the operator actually measures the amount of minute machining (step S703). Thereafter, the machining is resumed (step S704).
[0072]
In subsequent steps S705 to S709, processing is performed in the same procedure as in steps S203 to S207 of FIG. That is, the current position of the electrode 2 is ascertained by the discharge measurement under the conditions of the powder final finishing stage, and the measured minute machining amount is added to this to set the target depth position of the final machining. Processing to the final condition is performed (FIGS. 8C, 8D, and 8E).
[0073]
According to the present embodiment, not only the same effects as those of the first embodiment are obtained, but also the fine work-up amount is obtained by eliminating the thermal deformation or the like of the workpiece 3, so that higher accuracy can be obtained. A small amount of chasing can be performed.
[0074]
This embodiment is particularly useful when the discharge gap may be unknown and the workpiece has a large thermal deformation or the processing time is long.
[0075]
In addition, in each said embodiment, although implementation by the sculpture electric discharge machining was illustrated, it is not restricted to this, For example, it is applicable also when carrying out a small amount of additional machining from an already-processed surface by wire cut electric discharge machining. It is. In this case, the processed surface may be discharged with a wire wire under the final stage conditions and processed by adding the amount of additional processing from that position.
[0076]
【The invention's effect】
As described above, according to claims 1 and 4 of the present invention, a small amount of follow-up processing can be performed efficiently and accurately without requiring skill or troublesome work.
[0077]
According to Claims 2 and 5 of the present invention, a small amount of follow-up processing can be performed automatically and accurately.
[0078]
According to the third aspect of the present invention, it is possible to eliminate the influence of thermal deformation and perform a small amount of follow-up processing with higher accuracy.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an electric discharge machining apparatus according to a first embodiment of the present invention.
FIG. 2 is a view showing a flowchart of a procedure for a small amount of electric discharge machining in the same embodiment.
FIG. 3 is a schematic diagram showing a processing state corresponding to FIG. 2;
FIG. 4 is a diagram showing a test result of reproducibility of a discharge gap by powder electric discharge machining.
FIG. 5 is a diagram showing a flowchart of a procedure of a minute electric discharge machining in the second embodiment of the present invention.
6 is a schematic diagram showing a processing state corresponding to FIG. 5. FIG.
FIG. 7 is a flowchart showing a procedure of a minute electric discharge machining according to a third embodiment of the present invention.
FIG. 8 is a schematic diagram showing a machining state corresponding to FIG. 7;
FIG. 9 is a diagram for explaining a conventional method for determining the origin position of machining.
FIG. 10 is a diagram showing a relationship between a processing area and a discharge gap.
FIG. 11 is a diagram showing the relationship between the concentration of powder mixed in the machining fluid and the discharge gap.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Processing head 2 Electrode for electrical discharge machining 3 Work piece 3A Work surface 4 Processing table 10 Z-axis direction position detection device (current position acquisition means)
11 Automatic control device (processing control means)
12 Computer numerical control device (NC device) (current position storage unit (means), gap value storage unit (means), driving amount storage means, current position storage means)
13 Power Supply Control Device 14 Discharge Circuit 16 Controller Device (Driving Amount Acquisition Unit)

Claims (5)

In an electric discharge machining method of supplying a machining liquid to a machining gap between an electrode and a workpiece and discharging the workpiece by discharging with the electrode,
An actual measurement step for actually measuring the amount of machining to be applied to the workpiece surface of the workpiece ,
Acquiring for acquiring pre Symbol electrode the brought close to the working direction towards the surface to be processed of the workpiece, the position of the electrode at the time when the electrode has passed below 20 seconds 3 seconds from the start of discharge as the current position Process,
The current value obtained by adding the actually measured machining thrust amount by the actual measurement step to the position of the electrode obtained by the obtaining step, is set as the final position the electrodes to be reached, the final position until in discharge collector which has the set A processing step for performing processing,
An electric discharge machining method for a workpiece, wherein in the obtaining step and the machining step, electric discharge is performed with the same electrode under the same electrical conditions . Wherein the measured process first storing step stores Contact Ku in the amount storage unit thrust machining thrust amount that has been actually measured by, our Ku stored by the current position storage unit the current position of the electrode obtained by the obtaining step A second storage step, wherein the processing step adds a processing follow-up amount stored in the first storage step to a current position of the electrode stored in the second storage step. set as the final position to be reached, the set final position until in by processing discharge electric discharge machining method according to claim 1 Symbol mounting, characterized in that to perform the discharge machining automatically. The actual process, the working thrust amount, characterized that you actually measured after a sufficient time has passed to the A after processing before been to advance the influence of thermal deformation of the workpiece disappears discharge machining method according to claim 1 Symbol placement. In an electric discharge machining apparatus for supplying a machining liquid to a machining gap between an electrode and a workpiece and discharging the workpiece by discharging with the electrode,
Actual measurement means for actually measuring the amount of machining to be applied to the workpiece surface of the workpiece,
Acquiring for acquiring pre Symbol electrode the brought close to the working direction towards the surface to be processed of the workpiece, the position of the electrode at the time when the electrode has passed below 20 seconds 3 seconds from the start of discharge as the current position Means,
The current value obtained by adding the actually measured machining thrust amount by the actual measurement means to the position of the electrode obtained by the obtaining means, is set as the final position the electrodes to be reached, the final position until in discharge collector which has the set Processing means for performing processing,
The electric discharge machining apparatus characterized in that the acquisition means and the machining means discharge with the same electrical condition and the same electrode . Wherein a first storage means for storing the processed thrust amount that has been actually measured by measurement means, and a second storage means for storing the current position of the electrode obtained by the obtaining means, said processing means, said first the current value obtained by adding the machining thrust amount stored by said first storage means to the position of the stored said electrodes by second storage means is set as the final position to be reached is the electrode, or the set final position by processing discharge electric discharge machining apparatus according to claim 4, characterized in that to perform the discharge machining automatically.

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