JPH01205916A - Working error correction control in diesinking electric discharge machining - Google Patents

Abstract

PURPOSE:To improve the precision in the electric discharge machining by carrying out the position setting between an electrode and a workpiece before working by utilizing the characteristic in which the gap under the gap detection condition in the minute electric discharge converges to a specified value and diagnosing and correction-controlling the gap error or the working depth error generated during the electric discharge machining. CONSTITUTION:An electrode 1 is fed in a prescribed depth direction from a prescribed position for a workpiece 2, and the workpiece 2 is worked by controlling the feed of the electrode. Midway in the working, the switching to the gap detection condition for obtaining a specific value of the gap is performed, and the gap is converged, generating the minute electric discharge for a prescribed time. Then, the position of the electrode is measured, and the error quantity of the working gap for a prescribed value in planning the working or the error quantity of the working depth is calculated from the result of the measurement by a gap error correcting circuit 10. The electrode feed quantity is controlled so that the error quantity is corrected, and then working is restarted. Therefore, the electric discharge working with high precision can be executed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention eliminates alignment errors between an electrode and a workpiece before electrical discharge machining, and at the same time diagnoses machining errors due to gap changes that occur during electrical discharge machining. The present invention relates to a method for accurately correcting and controlling it, and is particularly suitable for increasing the precision of die-sinking electrical discharge machining.

[Conventional technology]

Die-sinker electrical discharge machines are widely used in various industries, centering on the mold industry, and among them, N (controlled electrical discharge machines), which can control multi-purpose machining, are becoming more and more popular. For example, there are techniques described in Japanese Patent Publication No. 61-58255 and Japanese Patent Application Laid-open No. 58-160018.

[Problem to be solved by the invention]

In general, as shown in FIG. 8, an NC-controlled electrical discharge machine is roughly divided into a machine main body that performs electrical discharge machining and a control power supply main body that has a built-in NG control device that performs a series of controls. X on bed 3
An x- and Y-table 4 with built-in axis and Y-axis drive mechanisms is mounted, and a processing tank 5 is disposed above the table, into which a workpiece 2 to be processed is attached.

Further, a quill 6 having a built-in Z-axis electrode feeding mechanism is supported by a support 7, and an electrode is attached to the tip of the tile. Reference numeral 8 denotes a machining fluid supply device, which is used to fill the machining tank 5 with machining fluid and to appropriately discharge machining products (machining waste, decomposition products of machining fluid, etc.) generated by electrical discharge machining. An appropriate amount of machining fluid can be supplied to the vicinity of the electrical discharge machining process. On the other hand, the NG control device 9a built in the control power supply main body 9 can set and register arbitrary machining conditions and control the machining power supply circuit 9C, and at the same time connects the electrode 1 and machining via the 3-axis drive control circuit 9b. It performs a series of controls necessary for electric discharge machining, including positioning control with object 2, driving the Z-axis electrode feed mechanism, controlling the electrode position during machining, and driving and swinging the table mechanism on the X- and Y-axes. It is now possible to do so.

Electrical discharge machining has traditionally been performed using NC-controlled electrical discharge machines configured in this way, but as industry has become more sophisticated in recent years, the demand for high-efficiency machining and especially high-precision machining has increased. ing.

Most of the machining accuracy of molded products by electric discharge machining is determined by the finishing process, but since there are many factors related to machining, it is necessary to fully understand the characteristics and interrelationships of each factor to effectively improve the accuracy of machining. As shown in Table 1, the factors related to machining accuracy that cannot be determined are (1) mechanical factors (2)
) control factors, (3) electrical discharge machining phenomenon factors, (4) temperature factors, and (5) other factors.

Table 1 Some of these factors are physically easy to countermeasure, while others are difficult. In particular, item (3) is difficult to countermeasure because it involves phenomena specific to electric discharge machining. be. Among these, machining errors due to machining gap changes that occur during electrical discharge machining have been pointed out as a major factor that degrades high-precision machining.

Furthermore, setting errors that occur during positioning of the electrode and workpiece before machining are also one of the factors that cannot be overlooked.

A situation in which such a gap-related error occurs will be specifically explained using hole machining as an example.

Figure 9 and Tables 2 to 4 outline the machining plan and condition selection for the machining specifications of the workpiece, and the method for calculating the electrode feed amount and swing radius according to the machining process. Table 2 shows an example of hole machining, Table 3 shows a machining plan, and Table 4 shows a calculation method for the electrode feed amount and swing radius.

Table 2 Table 3 CjJlO: m from the technical data file Table 4 Also, Fig. 10 is an enlarged view showing the electrode feed amount for this hole drilling. Furthermore, FIG. 11 shows that N shown in FIG.
An example of a flowchart of machining operations for actually performing machining using a C-controlled electrical discharge machine is shown. Generally, electrical discharge machining is performed in several steps from rough machining to final finishing machining, and the machining conditions for each are as follows: Machining speed 9 surface roughness, electrode wear rate,
Appropriate conditions are selected from the machining technology data file that describes the characteristics such as the machining gap.

Needless to say, under the conditions of rough machining, the discharge energy is large and high-speed machining can be performed, while under the conditions of finishing machining, the discharge energy is small and machining is performed at low speed in order to obtain the required surface roughness. In addition, in order to eliminate the influence of electrode wear, conditions are selected to minimize the electrode wear rate.

The electrode feed amount in the depth direction and the amount of oscillation in the radial direction are determined by adding and subtracting the machined surface roughness value and the gap gap value under each machining condition, as shown in Table 4, and based on this calculation result. Each is set. There is no particular need to perform rocking (r1=o) in the first machining, but if the diameter of the electrode used is smaller than a predetermined value, the predetermined machining is performed by adding the amount of rocking to correspond to the predetermined value. be able to.

By programming the machining details planned in this way,
The information is input into an NC-controlled electric discharge machine, and an electrode of a predetermined shape and a workpiece are installed at a predetermined position. After this preparation for machining is completed, actual machining operation begins, and the machining operation is executed as shown in the flowchart shown in FIG. The reference plane in the depth direction is set depending on the workpiece to be machined, but in order to make the explanation easier to understand, here it is set as the workpiece surface of the machined hole as shown in FIG. 10. This reference plane setting, which is performed before machining, has traditionally been performed by sensing contact between an electrode and a workpiece, and the same method is used here. Electric discharge machining is performed in the depth direction from this reference plane, and the electrode position is controlled so that the machining gap that follows the progress of the machining is kept within a certain appropriate range. As a method of controlling the machining gap, a method of detecting the average machining voltage between the machining poles and controlling it to a constant value is simple and has been widely used in the past. There are several other control methods, but in any case, unless the machining gap is maintained within an appropriate range, the discharge phenomenon will be disturbed and normal discharge machining cannot be maintained. 11th
In the figure, the steps indicate the order of the processing steps (see FIG. 8), and in this case, the steps are 1 to 6. The target value Zk of the electrode feed amount at this time is Zz~Ze, and the final raising machining Ze (Z
The processing is repeated in sequence until reaching , ).

When machining is carried out using such a method, errors related to the gap will occur. One is a setting error of the reference plane that occurs before machining, and the other is an error caused by a change in machining gap that occurs during machining. Positioning settings based on contact sensing eliminate dust that tends to form on the edges of the electrode surface, dirt that adheres to the surface of the workpiece, etc.
It is susceptible to the influence of dust and other inclusions, and the amount of error can reach several micrometers, making accurate reference leveling extremely difficult. As a positioning method other than touch sensing, there is a detection method that utilizes corona discharge by applying a high voltage, as disclosed in Japanese Patent Publication No. 61-58255, for example. If this detection method is used, it is possible to avoid the above problems, but it requires a special high-voltage power supply and control device with a voltage of about 1oOov, which is much higher than the normal electrical discharge machining voltage, and it also requires stability. Also requires caution. Furthermore, even if it is possible to utilize corona discharge in air, the phenomenon is different when using it in liquid or during processing, so it is difficult to handle it in the same way as in air.

On the other hand, the machining gap during electrical discharge machining is not always constant, but increases and decreases depending on various machining conditions, and fluctuates up and down in response to changes in electrical discharge machining phenomena due to the influence of machining products. For this reason, the preset machining gap (GAP) is not achieved, and the amount of difference from this set value will lead to machining errors. FIG. 12 and Table 5 show the electrode positions and gap errors after processing in the steps when processing was performed using the method shown in FIG. 11.

Table 5 If the actual gap value G& with respect to the set value Gk is excessive (
If G h < Ga ), over-machining will occur, and on the other hand, if G b > Ga ), there will be insufficient machining.

The amount of difference from the set value is greatly affected by electrical discharge and machining phenomena, and can range from several μm to several tens of μm. Therefore, with conventional technology, it is extremely difficult to eliminate machining errors caused by such gap changes. Therefore, high precision machining cannot be achieved.

As a method for measuring and correcting machining errors, for example, as disclosed in Japanese Patent Application Laid-Open No. 160018/1980,
There is a method in which the machining is interrupted midway, the machining depth is actually measured using an m constant probe, and then the error from the desired depth is corrected. However, since there is a processed product at the bottom of the processed hole immediately after processing, it is likely to be affected by this, making accurate measurement difficult. For this reason, a removal operation or a special removal device for this processed product is required, and the above method also requires a large-scale measuring device, which poses problems in terms of functionality and economy.

Therefore, as a result of various studies on control methods to eliminate machining gap errors, the present inventor discovered a characteristic in which the gap converges to a specific value under certain micro-discharge gap detection conditions, and further utilized this characteristic. , to set the alignment between the electrode and workpiece before machining, and to diagnose machining gap errors that occur during electrical discharge machining.

We have invented a method to accurately correct and control it.

An object of the present invention is to improve the accuracy of electric discharge machining by eliminating alignment errors before machining and gap errors during machining, and to provide an effective control method.

[Means to solve the problem]

The above purpose is to generate a small discharge for a predetermined time under gap detection conditions such that the gap between the electrodes set at predetermined positions and the workpiece becomes a specific value before starting machining, and then detect the position and use it to create a reference surface in the machining depth direction. After making the settings, start the specified machining, and then check the electrode position during machining at the point where the electrode feed reaches the specified depth during machining from the initial rough machining to the end of finishing machining. Then, from the machining conditions, switch to the gap detection conditions where the gap becomes a specific value, and after converging the gap while generating a micro discharge for a predetermined time, measure the electrode position at that time, and check the change in both measured values. The amount of error in the machining gap or the error in the machining depth is calculated from the predetermined value at the time of machining planning, and the electrode feed rate is controlled to correct the error amount and subsequent machining is restarted. achieved. In addition, after setting the reference surface in the same way as above, the specified machining is started, and then, in the process of steps from the initial rough machining to the end of finishing machining, the electrode position in the depth direction is set to the specified target value. After reaching and finishing the post-machining of that step, switch to the gap detection condition where the gap becomes a specific value, and after converging the gap while generating a micro discharge for a predetermined time,
After measuring the electrode position at that time and calculating the depth after machining in the above step from the measured value, the amount of error between the machining depth and the machining depth at the time of machining planning is calculated, and from this calculation result, it is determined that correction machining is necessary. This can also be achieved by performing correction processing by controlling the electrode feed amount to correct the amount of error when it is determined.

The machining error correction control method by die-sinking electric discharge machining according to claim 1 of the present application uses an NG control type electric discharge machine capable of various controls to move an electrode from a predetermined position to a predetermined depth with respect to a workpiece. In a method for correcting and controlling machining errors that occur during machining of a workpiece while controlling the electrode feed in the horizontal direction, switching to a gap detection condition in which the gap becomes a specific value in the middle of a predetermined machining, After converging the gap while generating a micro discharge for a predetermined period of time, the electrode position at that time is measured,
Furthermore, based on the measurement results, the amount of error in the machining gap or the amount of error in the machining depth with respect to the predetermined value at the time of machining planning is calculated,
The present invention is characterized in that the electrode feed amount is controlled so as to correct the amount of error, and subsequent machining is restarted.

The machining error correction control method in die-sinker electrical discharge machining according to claim 2 of the present application uses an NG control type electrical discharge machine capable of various controls to move an electrode from a predetermined position to a predetermined depth with respect to a workpiece. In a method for correcting and controlling machining errors that occur during machining of a workpiece while controlling electrode feed in the order of a series of machining steps from rough machining to finishing machining, a predetermined A small discharge is caused for a predetermined period of time under the gap detection conditions where the gap between the electrode and the workpiece set at each position becomes a specific value, and after setting the reference plane in the machining depth direction from the position detection, the specified machining is started. Then, in the middle of machining the step specified in the machining process, the electrode position during machining is measured at the point where the electrode feed reaches the specified depth, and one gap becomes a specific value based on the machining conditions. After switching to the gap detection condition and converging the gap while causing a micro discharge in advance for a predetermined time, measure the electrode position at that time, and from the amount of change in both measured values, calculate the machining gap relative to the predetermined value at the time of machining plan. The present invention is characterized in that the amount of error or the amount of error in machining depth is calculated, the electrode feed amount is controlled to correct the amount of error, and subsequent machining is restarted.

In each of the above claimed inventions, the calculation of the machining gap error amount or the machining depth error amount and its correction control are performed during the final step of machining, and can also be performed during the machining of a specified step if necessary. It is preferable to configure.

The machining error correction control method according to claim 3 of the present application uses an NC-controlled electric discharge machine capable of various controls to feed an electrode from a predetermined position to a predetermined depth direction with respect to a workpiece, and , in a method for correcting and controlling machining errors that occur during machining of a workpiece while controlling electrode feed in the order of a series of machining steps from rough machining to finishing machining, before starting machining,
A small discharge is caused for a predetermined period of time under the gap detection conditions in which the gap between the electrodes set at specific positions and the workpiece becomes a predetermined value, and after setting the reference surface in the depth direction from the position detection, the predetermined machining is performed. Then, in the process of each step from the rough machining to the end of finishing machining, after the electrode position in the depth direction reaches a specified target value and the machining of that step is completed, the gap reaches a specific value. After changing the gap detection condition to The amount of error in the machining depth with respect to the predetermined value at the time of machining planning is calculated, and if it is determined that correction machining is necessary from this calculation result, the electrode feed rate is controlled to correct the error amount and correction machining is performed. It is characterized by the fact that it is made to do. At this time, it is preferable to perform the correction processing after the final step processing, and also to perform the correction processing after the specified step processing as necessary.

[Effect]

As described above, in the present invention, position detection is performed by setting the alignment between the electrode and the workpiece before machining (reference plane setting) by causing a minute discharge for a predetermined period of time under the gap detection condition that the gap becomes a specific value. Therefore, it is possible to set an accurate reference plane and eliminate errors that tend to occur with conventional contact sensing methods. Furthermore, since gap errors occurring during electrical discharge machining are diagnosed and corrected and controlled, machining errors due to gap changes are eliminated and highly accurate machining results can be obtained.

〔Example〕

Hereinafter, the content of the present invention will be specifically explained using examples. 1st
1 is an example of a flowchart of a machining operation showing the contents of the present invention, and FIGS. 2 and 3 are explanations of the contents of the gap error correction disclosed in FIG. 1.

Table 6 shows the processing conditions in this flow.

Table 6 shows the overall configuration of the electrical discharge machine. In the figure, the processing power source 9 connected to the fl electrode and the workpiece 2 is connected to the NC control device 11.
A pulse voltage and an ilt current corresponding to predetermined machining conditions and gap detection conditions commanded by are output. The inter-electrode voltage detection circuit 24 detects the inter-electrode voltage of the discharge generated between the electrode 1 and the workpiece, sends the detection signal to the NC control device 11 and the electrode feed servo control circuit 16, and determines whether the discharge state is good or not. Let them determine. The electrode 1 is a Z-axis pulse servo motor 13
It is installed at the tip of an electrode feed mechanism 12 connected to the electrode feed mechanism 12 , and is driven and controlled by an electrode feed servo control circuit 16 via an amplifier 15 . The electrode feed servo control circuit 16 operates in response to a command signal from the NC control device 11, and appropriately controls the electrode position according to the result of discriminating the discharge state under each machining condition. In addition, it has a function to periodically move the electrode up and down under specified processing conditions and gap detection conditions. A pulse encoder 14 connected to a pulse servo motor 13 detects the movement position of the electrode 1 in response to a position command, and a zero gap error correction circuit feeds the detection signal back to the electrode feed servo control circuit 16 and the NC control device 11. 10 diagnoses a gap error or machining depth error in response to a gap detection command from the NC control device, and the diagnosis result is transmitted to the NC control device.

The workpiece 2 placed on the X, Y table 4 is mounted on the X, Y table mechanism, and is controlled by the X, Y table drive control circuit 23. A series of control commands for positioning with the electrodes and swinging the workpiece are transmitted from the NC control device 11. The pulse motors 18 and 19 for driving and the pulse encoders 20 and 21 for movement detection have the same function as the Z axis described above. Machining fluid is supplied and circulated (not shown) to the machining tank 5 from a machining fluid supply device, and at the same time, an appropriate amount of machining fluid is also supplied to the electric discharge machining near stop section, so that machining products can be appropriately discharged from the machining gap. It looks like this.

In this example, before machining, the reference plane in the depth direction is set at a predetermined position (the same workpiece surface of the machined hole as in the conventional method). A micro discharge is generated between the device and the object for a predetermined period of time. The gap detection conditions here are conditions where the discharge energy is extremely small, such as when performing best surface machining, and the applied voltage may be at the same level as normal machining conditions, for a predetermined period of time (for example, 20 to 30 minutes).
The gap is kept constant (about 60 seconds) by causing a slight discharge (about 60 seconds).
gc), and the point obtained by subtracting gc from the electrode position at the point where the gap becomes constant is the workpiece surface of the product to be processed, and becomes the reference plane. After setting the reference plane accurately in this way, a predetermined process is started. The predetermined machining is conventional (see FIG. 11), but in the present invention, as shown in FIG. 1, the gap error is diagnosed during the machining process and the error amount is corrected and controlled. Gap error correction control is performed as shown in FIGS. 2 and 3 in accordance with the correction command.

First, it is determined at what point during machining (step conditions) the electrode feed amount Z& is β short of a predetermined target value Zk (the value of β is, for example, The electrode position during processing at this point should be the point where the surface roughness value R+*axk) has been reached! After calculating the Za value,
Switch to the gap detection condition where the gap becomes a specific value gc, converge the gap while causing intermittent micro discharges for a predetermined time by vertical movement of the electrode as shown in the figure, and set the electrode position Z4 after convergence as above. Calculate in the same way. Since the ffl pole position fluctuates from moment to moment according to changes in the discharge phenomenon, a stable measurement position (for example, the point at timing time t□) is required.
It is recommended to determine the value at that position, measure the value several times, and average it. The reason why it takes a certain amount of time for the gap to converge to a specific value is because the processing products from the previous stage remain, and it is necessary to sufficiently remove them. Its role is to promote this. Convergence time t
It has been experimentally confirmed that c is approximately 30 to 60 seconds.

After that, the amount of change ΔG in both electrode positions was measured.

= Za Calculate the gap value G1 during machining from Za (GM
Δg4+gc)L, and the gap error amount ΔGk from the gap value Gk at the time of machining planning is calculated as shown in the figure (ΔG
Then, the calculated gap error amount is corrected to the electrode feed amount (ΔGk=ΔZ□) and processing is restarted. The electrode feeding amount Z/1 after correction is Zh + ΔZoh
becomes.

By performing correction control in this manner, machining errors due to gap changes that occur during machining can be eliminated, and machining accuracy is significantly improved compared to conventional methods. The above-mentioned gap error diagnosis and correction control can be performed during the machining of the final step, and the intermediate correction preceding it can also be performed during the machining of a specified step. Although not specifically described here, the depth Ha during machining and the machining depth error ΔHoh can also be calculated using a similar method.

FIGS. 5, 6, and 7 show other embodiments of the present invention. The reference plane setting based on the gap detection conditions is as described in FIG. 1, but the diagnosis of machining errors is performed here after step machining, and the necessity of correction machining is determined. That is, as shown in FIG. 6, after machining at the specified step, the gap detection conditions are changed to such that the gap becomes a specific value, and intermittent micro-discharge is generated for a predetermined period of time by the vertical movement of the electrode in the same way as above. Calculate (measure) the electrode position Z4 value after convergence. After calculating the machining depth H& (Ha=Zi+gc), the machining depth Hh at the time of machining plan is calculated.
Calculate the error amount AHOk (ΔHa h = HkHa
), then determine whether correction machining is necessary based on this calculation result, and if Hk > Ha, the machining depth is insufficient, and the error amount is corrected to the electrode feed amount (8 Ha k = ΔZah) and machining is restarted. do. The corrected electrode feed amount Z' is zk + ΔZOh
becomes. If Hh < Ha, there is no need to perform correction processing. By performing correction control in this manner, machining errors due to gap changes can be eliminated, and control can be simplified. The above machining error diagnosis (?l11 constant) and correction control may be performed after the final step of machining, or, if necessary, after machining of a designated step.

Note that Table 7 below shows the processing conditions.

Table 7 Note that the present invention is not limited to the round hole shape shown in the embodiment, but can also be applied to machining a wide variety of shapes and shapes with multiple rows.

〔Effect of the invention〕

As described above, the present invention utilizes the characteristic that the gap converges to a specific value under certain microdischarge gap detection conditions to set the alignment between the electrode and the workpiece before machining. Since gap errors or machining depth errors that occur during machining are diagnosed and corrected, it is possible to set an accurate reference surface, eliminate errors that tend to occur with conventional contact sensing methods, and further improve The difficult machining errors caused by gap changes are eliminated, and highly accurate machining results can be obtained. Furthermore, the control method of the present invention uses a simple control circuit to quickly and
Moreover, since it can be carried out accurately, the conventional method of interrupting machining to measure machining errors and its labor can be eliminated, and there is no need to use special measuring equipment, resulting in both operational and economical effects.

[Brief explanation of the drawing]

Fig. 1 is a flowchart of machining operation showing one embodiment of the present invention, Fig. 2 is a detailed flowchart of gap error correction control disclosed in Fig. 1, and Fig. 3 is a machining result according to the flow of Fig. 2. FIG. 4 is a device layout diagram showing the overall configuration of the NG control device implementing the present invention. FIG. 5 is a flow diagram of processing operation showing another embodiment of the present invention. The figure is a detailed flowchart of the machining depth error measurement and correction control disclosed in Figure 5, Figure 7 is a characteristic diagram showing the change in machining results over time according to the flow of Figure 6, and Figure 8 is a diagram of the conventionally used method. I'm N
A perspective view of a C-controlled electric discharge machine, FIG. 9 is a dimension definition explanatory diagram that defines the machining conditions in an example of hole machining, FIG. 10 is an enlarged sectional view near the machined hole showing the machined hole and electrode feed amount, and FIG. 1
Figure 1 is a flow diagram of machining operations showing a conventional example;
The figure is an explanatory diagram showing the electrode position and gap error when processed by the method disclosed in FIG. 11. DESCRIPTION OF SYMBOLS 1... Electrode, 2... Workpiece, 4... XY child table 5... Processing tank, 8... Processing liquid supply device, 9...
Processing power supply, 10... Gap error correction control circuit, 11...
・NG control device, 12... Electrode feeding mechanism, 13...
Pulse servo motor, 14, 20, 21... pulse encoder. 15.22...Additional device 11, 16...Electrode feed servo control circuit, 17...XY child table structure, 18, 19
...Pulse motor, 23...XY child table motion control circuit, 2nd 3rd port 4! Tolerance interval T 4th t -t pole /3- Novrus j-j<T-ta 2゛L i\ object /4.20
．． Luss L recorder with 2J-1. 4.
XY Chiful horse C meeting 11 ff? l f fraud circuit //
Nc*sumuhi 24-*Atl't
jrkk times ht2 Electric pressure feed + η1 Sth No. 6 Figure No. 7 Mouth No. 8 Concave No. 10 Day L- is loaded with pole 2... workpiece α now)! Figure II Early 12 Figure I... is a poem 2...1 crop

Claims (1)

[Claims] 1. Using an NC-controlled electric discharge machine capable of various controls, an electrode is fed from a predetermined position to a predetermined depth direction with respect to a workpiece, and the electrode feed is controlled. In this method, in the process of correcting and controlling machining errors that occur during machining of a workpiece, the gap detection conditions are changed so that the gap becomes a specific value in the middle of a predetermined machining process, and the gap is converged while generating a micro discharge for a predetermined period of time. After that, the electrode position at that time is measured, and from the measurement result, the error amount of the machining gap or the error amount of the machining depth with respect to the predetermined value at the time of machining plan is calculated, and the electrode feed is performed to correct the error amount. A machining error correction control method in die-sinker electrical discharge machining, characterized by controlling the amount and restarting subsequent machining. 2. Using an NC-controlled electric discharge machine that can perform various controls, feed the electrode from a predetermined position to a predetermined depth direction of the workpiece, and perform a series of machining steps from rough machining to finishing machining in order. In a method of correcting and controlling machining errors that occur during machining of a workpiece while controlling electrode feed, the gap between the electrodes set at predetermined positions and the workpiece becomes a specific value before machining starts. After making a small discharge for a predetermined time under the detection conditions and setting a reference plane in the machining depth direction by detecting the position, the predetermined machining is started. Measures the electrode position during machining at the point where the feed reaches the specified depth,
From the machining conditions, switch to the gap detection conditions where the gap becomes a specific value, and after converging the gap while generating a micro discharge for a predetermined time, measure the electrode position at that time, and from the amount of change in both measured values, It is characterized by calculating the error amount of the machining gap or the error amount of the machining depth with respect to the predetermined value at the time of machining planning, and controlling the electrode feed amount to correct the error amount and restarting the subsequent machining. A machining error correction control method in die-sinker electrical discharge machining. 3. Using an NC-controlled electric discharge machine that can perform various controls, feed the workpiece from a predetermined position to a predetermined depth direction of the electrode, and perform a series of machining steps from rough machining to finishing machining. In a method of correcting and controlling machining errors that occur during machining of a workpiece while controlling electrode feed, the gap between the electrodes set at predetermined positions and the workpiece becomes a predetermined value before the start of machining. After causing a micro discharge for a predetermined time under detection conditions and setting a reference plane in the depth direction by detecting the position, a predetermined machining is started, and then the process of each step from the rough machining to the end of finishing machining. Then, after the electrode position in the depth direction reached the specified target value and the machining of that step was completed, the gap detection conditions were changed to such that the gap becomes a specific value, and the gap was converged while generating a micro discharge for a specific time. After that, the electrode position at that time is measured, and the machining depth after the machining in the step is determined from the measured value, and then the error amount of the machining depth with respect to the predetermined value at the time of machining planning is calculated,
If it is determined that correction processing is necessary from this calculation result,
A machining error correction control method in die-sinking electrical discharge machining, characterized in that correction machining is performed by controlling an electrode feed amount so as to correct the amount of error.