JP3498413B2 - Electric discharge machining method and electric discharge machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machining method and an electric discharge machining method for automatically determining a machining remainder in die-sinking electric discharge machining, setting an additional machining amount for removing the machining remainder, and performing electric discharge machining. It relates to the device.

[0002]

2. Description of the Related Art In die-sinking electric discharge machining, multi-stage electric discharge machining for obtaining a desired shape by varying the electrical conditions such as peak current value and pulse width and the electrode position in multiple stages from rough machining to finishing machining. Is known as an important processing method because high processing efficiency can be obtained. At this time, the electric condition and the electrode position determining method at each stage are determined by experiments, experience, etc., and are disclosed in, for example, JP-A-2-218517.
Research is being carried out on the way of seeking as shown in.

Further, recently, in the final stage, an ordinary oil processing liquid is switched to a powder mixing processing liquid mixed with metal or metalloid powder, and this powder mixing processing liquid is formed by an electrode and a workpiece. A machining method of finishing the machined surface to a mirror surface by performing powder-mixed electric discharge machining in which it is supplied to the machining gap for machining is also common.

In this powder-mixed electric discharge machining, the surface roughness is 1 to 1 if the machining area is up to about 500 cm ² in the finishing machining.
In addition to finishing to a mirror surface of 2 μmRmax, machining stability is increased and processing speed is several times faster than before, but it has very excellent processing characteristics, but rough processing uses normal oil processing fluid In consideration of the life of the powder and filtration of the working fluid, the usual oil working fluid is used for processing from the 1st stage to the last step before the final stage. A processing method is adopted in which the processing liquid is switched to a powder-containing processing liquid for processing.

[0005]

[Problems to be Solved by the Invention] According to our research,
It has been known that the machining gap length in the electric discharge machining depends on the type of the machining fluid, and further on the change of the composition component due to the temporal variation of the machining fluid. In particular, it has been clarified that the machining gap length in powder-mixed electric discharge machining is greatly affected by the powder concentration in the machining liquid, and the smaller the powder mixture concentration, the smaller the machining gap length. For this reason, in the conventional electric discharge machine, when the machining fluid is switched to the powder-mixed machining fluid in the final stage and the powder-mixed electrical discharge machining is performed, the powder-mixed concentration of the powder-mixed machining fluid in the final stage changes every time the machining is repeated. In many cases, the machining gap length formed between the electrode and the workpiece gradually becomes smaller as the concentration of the mixed powder decreases, and the workpiece remains unmachined. There is a problem that the removal of the processing residue is a very troublesome work.

The present invention has been made in order to solve such a problem, and the density of the powder mixed in the working liquid and the compositional components are changed, so that the working gap length is reduced. It is an object of the present invention to provide an electric discharge machining method and an apparatus for the same, which can prevent the leftovers and can obtain desired surface roughness and precision of shape dimension.

[0007]

According to a first aspect of the present invention, there is provided an electric discharge machining method, wherein a pulse voltage is applied between a facing electrode and a workpiece through a machining liquid, and the electrode and the workpiece are machined. In an electric discharge machining method in which machining is performed by relatively moving an object, a real machining time for performing electric discharge machining by performing a relative movement given in advance is measured under a given electric condition.
And a second step of comparing the preset estimated time required to perform the relative movement with the actual machining time under the electrical conditions to determine the length thereof, and the actual machining time from the estimated time. If it is determined that the machining time is also short, the third step of setting the additional machining amount corresponding to this short time, and the electrical discharge machining in which the predetermined relative movement is performed under the predetermined electric conditions are performed. And a fourth step of performing electric discharge machining of the additional machining amount.

The electric discharge machining method according to the second invention is
The additional processing amount set in the third step of the first invention is
The machining gap length formed between the electrode and the workpiece is calculated from the difference between the actual machining time and the estimated time, and the additional machining amount is determined based on the machining gap length.

The electrical discharge machining method according to the third invention is
In the first or second invention, electric discharge machining is performed by using a machining liquid in which a powder substance of metal or metalloid is mixed in a machining gap formed by an electrode and a workpiece.

Further, the electrical discharge machining apparatus according to the fourth invention is
In an electric discharge machining apparatus that applies a pulse voltage between an electrode and a work piece and relatively moves the electrode and the work piece to perform electric discharge machining, given a predetermined electric condition under a predetermined electric condition. The actual machining time after performing the relative movement and the electrical discharge machining is compared with the estimated time corresponding to the preset actual machining time, and when the actual machining time is shorter than the estimated time, this shorter time Is provided with a control means for controlling so as to additionally process the processing amount determined in accordance with.

The electrical discharge machining apparatus according to the fifth invention is
In the electrical discharge machining apparatus, which applies a pulse voltage between the electrode and the workpiece opposite to each other via the machining fluid and relatively moves the electrode and the workpiece to perform electrical discharge machining, a predetermined electric power is applied. Under the conditions, measure the actual machining time after performing the relative movement given in advance and perform electrical discharge machining, and compare this actual machining time with the preset estimated time required to perform the relative movement under the electrical conditions. A comparison means for outputting the comparison result, a predetermined amount setting means for storing in advance an additional processing amount corresponding to the comparison result generated by the comparison means, a comparison result output by the comparison means, and the predetermined amount setting means. And a control means for generating and outputting an additional machining command in response to the additional machining amount corresponding to the comparison result.

Further, the electrical discharge machining apparatus according to the sixth invention is
In the electrical discharge machining apparatus, which applies a pulse voltage between the electrode and the workpiece opposite to each other via the machining fluid and relatively moves the electrode and the workpiece to perform electrical discharge machining, a predetermined electric power is applied. Under the conditions, measure the actual machining time after performing the relative movement given in advance and perform electrical discharge machining, and compare this actual machining time with the preset estimated time required to perform the relative movement under the electrical conditions. Then, comparing means for outputting the comparison result, predetermined amount setting means for generating and outputting the additional machining amount by receiving the actual machining time and the estimated machining time from the comparing means, and the actual machining time more than the estimated time. The control means for generating and outputting an additional machining command in response to the comparison result in the case of a short time and the additional machining amount.

The electric discharge machine according to the seventh invention is
In the fourth, fifth, and sixth inventions, the machining amount to be additionally machined is calculated from the difference between the actual machining time and the estimated time to obtain the machining gap length formed between the electrode and the workpiece, and based on the machining gap length. This is the amount of additional processing determined.

The electrical discharge machine according to the eighth invention is
In the fourth, fifth, sixth or seventh invention, a working liquid in which a metal or semimetal powder substance is mixed in a working gap formed by an electrode and a workpiece is used.

[0015]

In the electric discharge machining method according to the first aspect of the present invention, if the actual machining time for performing the electric discharge machining by performing the predetermined relative movement under the predetermined electrical conditions is shorter than the preset estimated time. It is determined that there is an unprocessed portion that has not been processed by the specified amount, an additional processing amount corresponding to the short time is set, and additional processing is performed to reach the specified amount in the fourth step.

In the second electric discharge machining method, the difference between the machining gap lengths is calculated from the difference between the actual machining time and the estimated machining time, and the difference between the machining gap lengths is added to the unmachined amount. And perform additional processing.

Further, in the third electric discharge machining method, by using the machining liquid mixed with the powder substance of metal or semimetal, when the actual machining time is shorter than the estimated time, the unprocessed portion of the dimensional accuracy is In addition, it is judged that there is a shortage of mirror surface finishing accuracy of the processed surface, and additional processing is performed.

Further, in the fourth electric discharge machining apparatus, the control means makes the actual machining time in which the electric discharge machining is performed by performing the relative movement given in advance under the electric condition given in advance, based on the estimated time set in advance. If it is too short, it is determined that there is an unprocessed portion that has not been processed by the specified amount, and the additional processing amount corresponding to the short time is set, and the additional processing amount is controlled to be additionally processed.

Further, in the fifth electric discharge machining apparatus, the actual machining time in which electric discharge machining is performed by performing a predetermined relative movement under a predetermined electric condition generated by the comparison means and a preset estimated time. The control means receives the result of comparison with
In this control means, the additional processing amount corresponding to the comparison result is called from the predetermined amount setting means, and if there is a processing amount to be added corresponding to the unprocessed amount, an additional processing command is generated and output.

Further, in the sixth electric discharge machining apparatus, the control means outputs the comparison result output from the comparison means when the actual machining time is shorter than the estimated time, and the actual machining output from the predetermined amount setting means. In response to the additional processing amount generated based on the time and the estimated processing time, it is determined that there is an unprocessed portion, and an additional processing command is generated and output.

In the seventh electric discharge machining apparatus, the difference between the machining gap lengths is calculated from the difference between the actual machining time and the estimated time, and the difference between the machining gap lengths is taken as the additional machining amount for the unmachined portion. Establish.

Further, in the eighth electric discharge machining apparatus, by using the machining liquid mixed with the powder substance of metal or semimetal, when the actual machining time is shorter than the estimated time, the unprocessed portion of the dimensional accuracy is In addition, it is judged that there is a shortage of mirror surface finishing accuracy of the processed surface, and the processing amount to be added is determined.

[0023]

【Example】

Example 1. This embodiment is an example in which a powder-mixed machining liquid is used in the final finishing step in multi-stage electric discharge machining, and this embodiment will be described with reference to FIGS. 1 to 4. Figure 1
Is an overall configuration diagram, and the configuration will be described based on the diagram. Reference numeral 1 is an electrode for electric discharge machining, 2 is a workpiece, 3 is a processing tank, 4 is a control device for controlling the entire control, and 5 is an electrode 1 by switching electrical conditions for each stage based on a command from the control device 4. A power source for applying a voltage to the workpiece 2 and the workpiece 2 to generate a pulsed discharge current in the machining gap formed between them, 6
a, 6b and 6c are servomotors that operate based on commands from the control device 4 to move the electrode 1 and the workpiece 2 relative to each other;
Is a working fluid tank for storing the normal oil working fluid 9, 8 is a working fluid tank for storing the powder-mixed working fluid 10, 11a, 11
Reference numeral b is a pump that pumps up the machining fluid stored in the machining fluid tanks 7 and 8 and supplies it to the machining tank 3, and its operation is also controlled by a command from the control device 4. And 1
Reference numerals 2a, 12b, 12c, and 12d are control valves that perform opening / closing operations based on commands from the control device 4.

Reference numeral 20 denotes a comparison device for comparing the actual machining time with the estimated time estimated in advance and outputting the time difference. The inside of the comparator 20 starts electric discharge machining based on a command from the control device 4. A timer unit 21 that measures a time to reach a preset machining end position, a time setting unit 22 that presets an estimated time required for machining, and an actual machining time measured by the timer unit 21 and an estimate set in the setting unit. The comparison unit 23 compares the times and outputs the difference information. Reference numeral 24 is a predetermined amount setting unit in which the additional processing amount corresponding to the difference information is preset and registered. Further, the actual machining time measured by the timer unit 21 is reset every time the electrical condition is changed and every time the electrode 1 is changed to machining in a direction opposite to the workpiece 2 or swing machining.
It is compared with the estimated time of machining in the facing direction or the estimated time of rocking machining under each electric condition set in the time setting unit 22.

FIG. 2 is a diagram showing the positional relationship between the electrode and the workpiece during multi-stage electric discharge machining. The operation will be described below with reference to FIG. When machining is performed until the desired surface roughness and shape are obtained while changing the electrical condition and the position of the electrode under each electrical condition in multiple steps based on the command from the control device 4, first, the pump 11a is based on the command from the control device 4.
And the control valve 12a operate to pump up the normal oil processing liquid 9 in the processing liquid tank 7 by the pump 11a, and the control valve 1
It is supplied into the processing tank 3 via 2a. And processing tank 3
A sufficient amount of the normal oil processing liquid 9 is supplied into the electrode 1 and the workpiece 2
After the machining liquid has been filled between them, the machining voltage 5 is switched to the electrical condition of the first stage based on the command 1 of the control device 4, and the pulsed power supply is supplied to the electrode 1 and the workpiece 2. . As a result, electric discharge occurs between the two via the machining liquid 9 and electric discharge machining starts.

At this time, the servomotors 6a, 6b, 6c send the electrode 1 to the position Z1 in the direction opposite to the workpiece 2 based on the command from the controller 4, and then oscillate on a plane perpendicular to the opposite direction. The electric discharge machining is performed so as to draw a loop having a radius of gyration R1 (hereinafter, this is referred to as swing machining). That is, the first
The predetermined electrode position at the stage is the processing depth Z1 and the swing radius R1. Then, under the electrical conditions of the first stage, the electrode 1 reaches the processing depth Z1, and then the swing radius R1.
When the rocking machining is performed, the control device 4 outputs a command to switch the machining power source 5 to the electrical condition of the second stage, and
A command is sent to the servomotors 6a, 6b, 6c to feed the electrode 1 in a direction opposite to the workpiece 2 to a working depth Z2, and then swing machining with a swing radius R2 is performed. Repeat until the nth stage. During this period, the comparison device 20 compares the actual machining time with the estimated time, and if there is a significant difference between them, the control device calls a corresponding additional machining amount from the predetermined amount setting unit and generates a command to perform the additional machining. Output.

When powder-mixed electric discharge machining is performed at the n-th stage of the final stage, when the machining at the (n-1) th stage is completed, the machining is temporarily interrupted based on a command from the control device 4, and the machining tank is processed. The normal oil working liquid 9 in 3 is discharged to the working liquid tank 7 through the control valve 12c, and when the discharge is completed, the powder mixed working liquid 10 in the working liquid tank 8 is pumped up by the pump 11b, and through the control valve 12b. Supply to processing tank 3, processing tank 3
When the powder-mixed working liquid 10 is sufficiently supplied and filled between the electrode 1 and the workpiece 2, the machining power supply 5 applies a pulse voltage to the electrode 1 and the workpiece 2 based on a command from the controller 4. And electric discharge is generated between the two via the powder-mixed machining liquid 10 to start electric discharge machining, and the servomotors 6a, bb, 6c cause the electrode 1 to work on the workpiece 2 based on a command from the controller 4. The workpiece is fed to the machining depth Zn in the direction opposite to, and then oscillated with the oscillating radius Rn to proceed with the machining and complete the entire machining.

The electrical conditions from the first stage to the nth stage, the working depths Z1 to Zn for each electrical condition, and the swing radius R1
~ Rn Estimated processing time, additional processing amount, etc. are determined in advance based on experiments and experience, and are set in advance by the operator in the control device 4, the comparison device 20, the predetermined amount setting unit 24, etc. before starting the processing. It

FIG. 3 shows the relationship between the working depth of the electrode 1, the working depth of the work piece 2, and the working gap length when multi-step working is performed in the direction in which the electrode 1 and the work piece 2 face each other. Yes, the mechanism of additional processing in the depth direction (opposing direction) will be described with reference to the drawings. When the electrode 1 reaches the processing depth Zn-1 which is the predetermined position of the (n-1) th stage, the processing depth Dn-1 of the workpiece 2 is the processing under the electrical conditions of the (n-1) th stage. When the gap length is Gn-1, it can be expressed as Dn-1 = Zn-1 + Gn-1 (1). After that, it is assumed that the electrical conditions are switched and the processing of the nth stage is started. At the n-th electrode, since the processing of the n-th step is completed when the electrode 1 reaches the processing depth Zn, the movement amount of the electrode 1 at the n-th step (hereinafter, this is referred to as an electrode feed amount) is The electrode feed amount at the n-th stage = Zn−Zn−1 (2). However, in the n-th stage, since the discharge is started from the machining depth Dn-1 of the work piece in the (n-1) th stage to the machining gap length Gn in the electrical condition of the n-th stage, the n-th stage is started. The discharge start position of is from the formula (1), the discharge start position of the n-th stage = Dn-1-Gn = Zn-1 + Gn-1-Gn (3).

Therefore, in the n-th stage, when the electrode 1 moves from the processing depth Zn-1 to Zn, the movement amount actually contributing to the processing (hereinafter, this is referred to as the machining amount) is expressed by the formula ( From 3), the machining amount of the nth stage = Zn− (Zn−1 + Gn−1−Gn) = (Zn−Zn−1) + (Gn−Gn−1) (4). Therefore, even if the electrode feed amount of the nth stage is set to be the formula (2), the actual machining amount of the nth stage is represented by the formula (4). When the machining gap length of 2 becomes smaller, the machining amount of the n-th stage decreases. At this time,
Since the processing surface formed by the processing up to the (n-1) th stage cannot be completely cut off and the processing is completed even though the electrode 1 reaches the predetermined processing depth Zn of the nth stage, In a direction in which the electrode 1 and the workpiece 2 are opposed to each other, a situation occurs in which desired machined surface roughness and shape accuracy cannot be obtained (the same applies to rocking machining).

However, in such a case, there is a significant difference between the actual machining time measured by the timer unit 21 and the estimated time stored in the time setting unit 22, and the difference information output from the comparison unit 23. Based on the above, the control device 4 calls the corresponding additional machining amount from the predetermined amount setting unit 24 to generate and output the additional machining command. Hereinafter, this mechanism will be described.

The processing depth of the (n-1) th stage electrode 1 is set to Zn-
Even if the machining depth of the 1st and nth stages is set to Zn and the electrode feed amount is set as represented by the formula (2) in the nth stage, the actual machining amount is represented by the formula (4). It is represented by. Therefore,
It can be considered that the time required for the electrode 1 to travel from the processing depth Zn-1 to the processing depth Zn is proportional to the processing time of the machining amount represented by the formula (4). That is, assuming that the time required for the processing of the nth stage is Tn and the processing speed under the electrical conditions of the nth stage is Vn, Tn = (Zn-Zn-1) / Vn = {(Zn-Zn-1 ) + (Gn-Gn-1)} / Vn (5). At this time, as described above, the processing gap length of the n-th stage becomes small due to the decrease of the powder mixture concentration, the processing gap length becomes Gn ′ (Gn ′ <Gn), and the set processing depth of the electrode 1 is Zn. As it is, the time Tn ′ for the electrode 1 to reach the processing depth Zn is Tn ′ = {(Zn−Zn−1) + (Gn′−Gn−1)} / Vn (6), and Gn ′ <Gn Therefore, from equations (5) and (6), Tn '<Tn (7). Therefore, when the machining gap length is reduced, the actual machining time measured by the timer unit 21 of the nth stage is set to the time setting unit 21.
It is shorter than the estimated time set in. If the comparison unit 23 detects the shortened machining time, it can be seen that the machining gap length is reduced.

That is, the time setting unit 2 in the comparison device 20.
The estimated time Tn for the electrode 1 to reach the processing depth Zn-1 to Zn when the processing gap length is Gn under the electrical condition of the nth stage is set to 2. Then, when the processing of the n-th stage is started, the timer unit 21 counts the actual processing time Tn ′ actually required for the electrode 1 to reach the processing depths Zn−1 to Zn, and the comparison unit 23 Compare Tn and Tn '. If Tn '<Tn (8), it is determined that the machining gap length Gn has decreased, the comparison device 20 sends a signal to the control device 4, and the control device 4 sets the predetermined amount setting unit 24. Servo motors 6a, 6b, 6 so that the electrodes are sent by the amount, for example, ΔZ, for processing.
A command is issued to c and processing is performed again up to the position of processing depth Zn + ΔZ. Here, it is apparent that ΔZ may be the reduced amount of the machining gap length Gn, and can be expressed as in equation (9). ΔZ = Gn−Gn ′ (9) However, since it is difficult to easily grasp Gn ′, for example, when the powder mixture concentration becomes half or less of the normal level, the desired characteristics are obtained regardless of the machining amount due to the machining characteristics. If a value that cannot give a mirror finish is found in advance through experiments, etc. and is set as G ", the processing gap length Gn when the powder mixture concentration is regular and the processing gap length when the powder mixture concentration is half the regular concentration The difference from Gn ″, ΔZ = Gn−Gn ″ (10), is sufficient.

Therefore, when the electrode has to be sent over ΔZ given by the equation (10), it is the same as the powder concentration in the working liquid is less than half of the normal value, so that the working time is longer. It is not possible to obtain the desired machined surface just by hanging it. Therefore, by setting the value of ΔZ in the expression (10), it is possible to surely obtain a desired mirror-finished machined surface unless the powder mixture concentration is equal to or less than the normal half. Incidentally, FIG. 4 shows the relationship between the powder mixture concentration and the processing gap length.

As a result, it is possible to prevent an unprocessed surface from being left unprocessed due to a reduction in the processing gap length, and to reliably obtain a processed surface having a desired surface roughness.

Example 2. FIG. 5 is a block diagram showing another embodiment of the present invention. In FIG. 5, 25 is a comparison device 20.
Receives signals from the timer unit 21 and the time setting unit 22 in the
This is a calculation device that calculates a predetermined amount ΔZ.

In the first embodiment, the predetermined amount ΔZ is given by the formula (1
Although it is set as an amount that can be represented by 0), when the shape accuracy is important in addition to the machined surface roughness, an accurate ΔZ is required. In such a case, ΔZ is obtained as follows.

The machining gap length in the nth stage machining is Gn.
The difference ΔT between the processing time Tn at the time of and the processing time Tn ′ at the time of the processing gap length Gn ′ is ΔT = Tn−Tn ′ = (Gn−Gn ′) / Vn from the equations (5) and (6). (11) becomes, and if Gn and Vn are experimentally checked in advance and ΔT is measured, Gn ′ can be obtained by solving the equation (11) for Gn ′.

Therefore, in the processing of the nth stage, the electrode 1
Time to reach the processing depth Zn is measured by the timer unit 21 in the comparison device 20, the time setting unit 22 sets the processing time Tn when the processing gap length Gn is set, and the calculation device 25 sets the timer unit 21 to By receiving the signal from the time setting unit 22, the expression (1
By solving 1) for Gn ′ and executing the equation (9), an accurate predetermined amount ΔZ can be obtained, and this result is set in the predetermined amount setting unit 24. Then, as in Example 1, the comparison device 20 sends a signal to the control device 4 when Tn ′ <Tn, and the control device 4 sets the amount set in the predetermined amount setting unit 24 for the processing depth Zn. A command is issued to the servomotors 6a, 6b, 6c to perform further machining by ΔZ, and machining is performed again up to the machining depth Zn + ΔZ.

As a result, it is possible to prevent the unmachined surface from being left unprocessed due to the reduction of the machining gap length, and to obtain not only the desired surface roughness but also the machining result in which the shape accuracy is sufficiently satisfied.

In the first and second embodiments, the case where the electrode 1 and the workpiece 2 are machined in the opposite direction has been described. However, by substituting the machining depth Z with the oscillating radius R, the oscillating machining can be naturally performed. It goes without saying that the same effect can be obtained.
Further, although the example using the powder-mixed working liquid has been described, it is needless to say that the same effect can be obtained by applying to a general working liquid in which the working gap length changes due to the change of its composition component.

[0042]

Since the present invention is constructed as described above, it has the following effects.

According to the first aspect of the invention, the actual machining time is measured in the first step, the length of the estimated time and the actual machining time is judged in the second step, and the actual machining time is shorter than the estimated time. In this case, it is determined that there is an unprocessed part that has not been processed by the specified amount, the additional processing amount corresponding to the short time is set in the third step, and the unprocessed part is removed in the fourth step. Therefore, it is possible to automatically manufacture a high-quality product having a desired finished surface and processing accuracy without leaving an unprocessed surface.

According to the second invention, the difference between the machining gap lengths of the two is calculated from the difference between the actual machining time and the estimated time,
The difference amount of the processing gap length is defined as the additional processing amount for the unprocessed portion, and the additional processing can be performed. In addition to the first invention,
Further, the processing accuracy is improved.

Further, according to the third aspect of the invention, by using the processing liquid mixed with the powder substance of metal or metalloid, when the actual processing time is shorter than the estimated time, the unprocessed portion of the dimensional accuracy is In addition to this, it can be judged that there is a shortage of mirror surface finishing accuracy of the machined surface, and additional processing can be performed. In addition to the first or second invention, the processing accuracy of mirror surface finishing processing is further improved.

According to the fourth aspect of the invention, if the actual processing time is shorter than the estimated time given in advance, it is judged that there is an unprocessed portion that has not been processed by the specified amount. The corresponding additional processing amount can be set and controlled by the control means to perform additional processing of this additional processing amount, and there is no leftover of the processing surface, and a high quality product with the desired finishing surface and processing accuracy is automatically produced. Can be manufactured in a simple manner.

According to the fifth aspect of the invention, the control means receives the comparison result of the actual machining time and the estimated time generated by the comparison means, and the control means receives the additional machining amount corresponding to the comparison result. Is called from the predetermined amount setting means, and if there is a processing amount to be added corresponding to the unprocessed amount, an additional processing command can be generated and output, there is no leftover of the processed surface, and the desired finished surface and processing accuracy. It is possible to automatically produce a high quality product having

According to the sixth aspect of the invention, when the actual machining time is shorter than the estimated time, the comparison result output from the comparison means and the predetermined amount setting means generate the actual machining time and the estimated time. The control means receives the additional machining amount and determines that there is an unmachined portion, and can generate and output an additional machining command, and there is no leftover of the machining surface, and the desired finishing surface and machining accuracy are obtained. High quality products can be produced automatically.

According to the seventh invention, the difference between the machining gap lengths of the two is calculated from the difference between the actual machining time and the estimated time,
The difference amount of the machining gap length can be determined as the additional machining amount for the unmachined portion, and the machining accuracy is further improved in addition to the fourth, fifth or sixth invention.

Further, in the eighth electric discharge machining apparatus, by using the machining liquid mixed with the powder substance of metal or metalloid, when the actual machining time is shorter than the estimated machining time,
In addition to the unfinished dimensional accuracy, it can be determined that there is a lack of mirror surface finishing accuracy of the machined surface, and the amount of machining to be added can be determined. In addition to the fourth, fifth, sixth or seventh invention, The finishing precision is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram illustrating multi-step processing.

FIG. 3 is a diagram showing a relationship among a machining depth of an electrode, a machining depth of a workpiece, and a machining gap length.

FIG. 4 is a diagram showing a relationship between a powder mixture concentration and a processing gap length.

FIG. 5 is a configuration diagram showing a second embodiment of the present invention.

[Explanation of symbols]

1 electrode, 2 workpiece, 3 processing tank, 4 control device,
5 Processing power supply, 6a, 6b, 6c Servo motor, 7
Working fluid tank, 8 Working fluid tank, 9 Normal oil working fluid,
10 powder mixed working fluid, 11a, 11b pump, 12
a, 12b, 12c, 12d control valve, 20 comparison device, 21 timer unit, 22 time setting unit, 23 comparison unit, 24 predetermined amount setting unit, 25 calculation device.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-1-205916 (JP, A) JP-A-4-35811 (JP, A) JP-A-52-38952 (JP, A) JP-A-3- 111122 (JP, A) JP-A-6-114637 (JP, A) JP-A-4-105823 (JP, A) JP-A-58-160018 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B23H 7/28

Claims (8)

(57) [Claims] 1. An electric discharge machining method in which a pulse voltage is applied between an electrode and a workpiece that face each other via a machining liquid, and the electrode and the workpiece are relatively moved to perform machining. A first step of measuring an actual machining time in which a predetermined relative movement is performed and an electric discharge machining is performed under a given electric condition, and a preset estimated time required for performing the relative movement under the electric condition And a second step of comparing the actual processing time with the actual processing time and determining the length thereof, and when it is determined that the actual processing time is shorter than the estimated time, an additional processing amount corresponding to the shorter time is set. An electrical discharge machining method comprising: a third step; and a fourth step of performing electrical discharge machining of a predetermined relative movement and then performing electrical discharge machining of the additional machining amount under the predetermined electrical condition. 2. The additional machining amount to be additionally machined is determined on the basis of the machining gap length obtained by obtaining the machining gap length formed between the electrode and the workpiece from the difference between the actual machining time and the estimated time. The electric discharge machining method according to claim 1, wherein the amount is an additional machining amount. 3. The electric discharge machining method according to claim 1, wherein the machining gap formed by the electrode and the workpiece is subjected to electric discharge machining using a machining liquid mixed with a metal or semimetal powder substance. The electrical discharge machining method according to item 2 or item 2. 4. An electric discharge machining apparatus for performing electric discharge machining by applying a pulse voltage between an electrode and a workpiece which are opposed to each other via a machining liquid and by relatively moving the electrode and the workpiece. Under a given electric condition, the actual machining time in which the predetermined relative movement is performed and the electric discharge machining is performed is compared with the estimated time corresponding to the preset actual machining time, and the actual machining time is compared. An electric discharge machining apparatus, comprising: a control means for controlling, when the time is shorter than the estimated time, an additional machining amount determined corresponding to the shorter time. 5. An electric discharge machining apparatus for performing electric discharge machining by applying a pulse voltage between an electrode and a workpiece, which are opposed to each other via a machining liquid, and by relatively moving the electrode and the workpiece. Under a given electrical condition, measure the actual machining time after performing the relative movement given in advance and perform the electrical discharge machining, and set a preset estimate required to perform the relative movement under the actual machining time and the electrical condition. Comparing means for comparing the time and outputting the comparison result; predetermined amount setting means for storing in advance the additional machining amount corresponding to the comparison result generated by the comparing means; and the comparison result output by the comparing means. An electric discharge machining apparatus comprising: a control unit that receives an additional machining amount corresponding to the comparison result from the predetermined amount setting unit and generates and outputs an additional machining command. 6. An electric discharge machining apparatus for performing electric discharge machining by applying a pulse voltage between an electrode and a workpiece which face each other with a machining liquid interposed therebetween and by relatively moving the electrode and the workpiece. In, under the given electrical conditions, measure the actual machining time after performing the relative movement given in advance and perform electrical discharge machining, and set the actual machining time and the preset required for performing the relative movement under the electrical conditions. Comparing means for comparing the calculated estimated time and outputting the comparison result; a predetermined amount setting means for generating and outputting an additional machining amount by receiving the actual machining time and the estimated machining time from the comparing means; An electric discharge machining apparatus comprising: a control unit that receives a comparison result when a machining time is shorter than an estimated machining time and the additional machining amount, and generates and outputs an additional machining command. 7. The machining amount to be additionally machined is determined based on the machining gap length obtained by obtaining the machining gap length formed between the electrode and the workpiece from the difference between the actual machining time and the estimated machining time. The electric discharge machining apparatus according to claim 4, 5 or 6, wherein the amount is an additional machining amount. 8. An electric discharge machining apparatus for performing electric discharge machining using a machining liquid in which a metal or semimetal powder substance is mixed in a machining gap formed by the electrode and a workpiece. The electric discharge machine according to any one of items 4, 5, 6 and 7.