JP2722898B2 - EDM control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electric discharge machine which can always maintain a desired machining state.
In particular, it relates to the control of an electric discharge machine which can easily maintain the desired machining state easily by always describing a plurality of methods for realizing a desirable machining state such as machining know-how as a knowledge base and controlling based on this. Things.

[0002]

2. Description of the Related Art FIG. 13 shows, for example, Japanese Patent Publication No. 62-107.
It is a block diagram of the adaptive control apparatus of the conventional electric discharge machine shown in No. 69 publication. In the figure, 1 is a machining electrode, 2 is a workpiece, 3 is a machining tank containing a machining fluid 4, 5 is a main shaft for moving the machining electrode 1 in the Z-axis direction, 6 is a drive motor for driving the main shaft 5, 7 Is a speed / position detector for detecting the moving speed and position of the main shaft 5, 21 is an electrode position control unit for giving a drive command to the drive motor 6 to control the position of the machining electrode 1, and 22 is the machining electrode 1 and the workpiece. 2 is a processing power supply for supplying a processing voltage between the power supply 2 and the power supply 2. 23 is an electrode position control unit 2 which takes in a detection signal from the speed / position detector 7 and a gap voltage to perform arithmetic processing;
1 is a detection value processing unit that gives a feedback command to the machining power supply 22 and gives an ascending or lowering of the extreme lower point to the adaptive control unit 31. Adaptive control unit 31
Sends a processing command for adaptive control to the electrode position control section 21 and the processing power supply 22 based on a command signal from the detection value processing section 23.

Next, the operation of the prior art will be described. When a pulsed voltage is applied between the machining electrode 1 and the workpiece 2 from the machining power supply 22, a discharge occurs in the machining fluid between the two, and
The workpiece 2 is machined by the discharge phenomenon and the feeding operation of the machining electrode 1. The electrode position control unit 21 compares the average voltage between the electrodes obtained from the detection value processing unit 23 with a reference voltage in order to keep the gap between the processing electrode 1 and the workpiece 2 appropriate for discharge.
The drive motor 6 is controlled in accordance with the difference voltage to process the machining electrode 1.
Control the feed position or feed speed.

In electric discharge machining, the gap between the machining electrode 1 and the workpiece 2 is generally narrow, such as about 10 to several tens of microns. Especially when the machining area is large, machining chips generated by machining pass through the gap. And it is hard to be discharged. For this reason, abnormal electric discharge is likely to occur, for example, such that machining waste stays in the processing gap and electric discharge concentrates on that portion. This situation occurs because the amount of processing waste exceeds the discharge capacity.To prevent this, an abnormal condition is detected or predicted to reduce the amount of processing waste, It is only necessary to take measures such as increasing the discharge capacity of the wastewater.

FIGS. 14A and 14B show the movement of the position of the machining electrode 1. FIG. 14A shows a case where normal machining is performed.
(B) is a case where an abnormality occurs in the machining gap. The machining electrode 1 oscillates about several microns to several tens of microns along with the machining, but when normal machining is performed, each pole lower point 100 which moves from the time when the machining electrode 1 is lowered to the time when the machining electrode 1 is ascended is processed. Is gradually descending as it progresses. However, when an abnormality occurs in the machining gap, as shown in FIG.
00 tends to rise. Therefore, this extremely lower point 100
In order to detect the rise in the amount of machining waste and to suppress the generation amount of machining waste, the pulse width of the current pulse supplied from the machining power supply 22 is shortened, and the discharge pause width is increased. It can be seen that measures such as increasing the periodic lifting amount of the processing electrode 1 should be taken in order to enhance the discharge capability of the processing waste.

[0006] In FIG. 13, a detection value processing unit 23 detects the extreme point 100 from the movement of the machining electrode 1 obtained from the speed / position detector 7, and the adaptive control unit 31 raises or lowers the extreme point 100. Inform. The adaptive control unit 31 determines that an abnormality has occurred in the machining gap when the rise exceeds a certain threshold value, and for example, shortens the pulse width of the current pulse, Lengthen. Alternatively, a command to increase the electrode lifting amount in order to increase the discharge capability of the processing waste is sent to the electrode position control unit 21 and the processing power supply 22. As is clear from the above explanation,
Control such as shortening the pulse width of the current pulse or increasing the periodic pull-up amount of the machining electrode 1 is indispensable for preventing abnormal discharge from occurring.

[0007] In addition to the above prior art, Japanese Patent Laid-Open No. Sho 56-1
No. 07831 (Japanese Patent Publication No. 61-58252). This is because the electrode position detecting means for detecting the difference between the deepest position where the electrode is fed into the workpiece and the current position of the electrode, and when the difference is large, it is determined that the gap state is in a bad state and the signal is output. And a gap state discriminating means for outputting the output of the electric discharge machining, and capable of accurately detecting the quality of the gap state in the electric discharge machining.

[0008]

In the conventional control device for an electric discharge machine described above, the lowest point of the electrode is raised, or the deepest position where the electrode is fed into the workpiece and the current position of the electrode. When the difference from the value exceeds a certain threshold value, it is determined that an abnormality has occurred in the machining gap, and in order to suppress the machining removal capability (the amount of machining waste), for example, the pulse width of the current pulse is reduced and the Control is performed by changing the processing conditions so as to increase the pause width or increase the electrode pull-up amount in order to increase the processing chip discharge capability.

However, when the elevation of the lowermost point of the electrode or the difference between the deepest position of the electrode and the current position exceeds a certain threshold value, it is determined that an abnormality has occurred in the machining gap, and the machining condition is changed to control. However, there is a problem that control is complicated due to the use of the technique of performing the control. Particularly, for a skilled worker, various movements of the processing electrode 1, the processing electrode 1 and the workpiece 2
The stability of the electric discharge machining state is determined from the data on the amount of electricity during the discharge, and the discharge pause width and the amount of the electrode raised at regular intervals are changed accordingly. When controlling the pulse width of the current pulse and the amount of periodic pull-up of the electrode in accordance with the stability of the electric discharge machining state on behalf of the skilled worker, it is difficult to accurately describe the criteria for the skilled worker. There was a point.

In order to solve the above problems, the present applicant has filed Japanese Patent Application No. 63-189844 (Japanese Unexamined Patent Application Publication No.
No. 31838) discloses an adaptive control device for an electric discharge machine. The adaptive control device of the electric discharge machine stores a method for recognizing a machining state in a knowledge storage unit, and detects a machining state required in this method by a detection value processing unit. Is stored in the situation storage unit, and the inference unit combines a plurality of results obtained from the technique from the knowledge storage unit and the machining situation amount from the situation storage unit to obtain a machining state or an amount equivalent thereto. The operation amount is determined by the processing condition changing unit by using. This makes it possible to appropriately and easily describe techniques possessed by a skilled worker regarding changes in machining conditions and criteria for determining the stability of an electric discharge machining state, and to execute optimal machining conditions by using these techniques, and to adaptively execute them. Changes can now be made automatically.

However, when the difference between the deepest position of the electrode and the current position greatly exceeds a certain threshold value and gradually returns to the deepest position of the electrode, it is determined that an abnormality has occurred in the processing gap and the processing conditions are changed. Control. In addition, since it is not possible to accurately determine the sporadic unstable phenomenon, for example, the difference between the deepest position of the electrode and the current position exceeds a certain threshold value only during one or two electrode lifting periods. In such a case, there is a problem that it is determined that an abnormality has occurred in the machining gap and the machining conditions are changed to perform control, and adaptive control closer to a skilled worker is not performed, thereby lowering machining efficiency.
In the case of an unstable phenomenon in which the amount of movement of the electrode, which is one of the various movements of the machining electrode 1 from the deepest position, has occurred, the proposed adaptive control method of the electric discharge machine is used. There is a problem that the processing conditions are not optimally changed only by controlling the processing conditions.

[0012] Such an unstable phenomenon in the machining state is apt to occur when electric discharge machining is performed using a machining electrode made of a copper material without supplying a machining fluid to a machining gap. Is more likely to occur when the depth becomes deeper or in the swing processing of the finishing processing. In particular, it tends to occur when machining powder generated by electric discharge machining enters the machining gap. In the present circumstances,
A skilled worker monitors the stability of the electric discharge machining state, and changes the above operation in accordance with the situation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to appropriately and easily describe a technique of a skilled worker regarding a criterion for judging the stability of the electric discharge machining state, and to describe these methods. It is an object of the present invention to provide a control device for an electric discharge machine capable of automatically executing optimum machining control and appropriately changing the machining control by a technique.

[0014]

A control device for an electric discharge machine according to the present invention detects a movement amount from a most advanced electrode position to the present (a movement amount from an electrode deepest position) in a predetermined sampling section. Means, means for storing the movement amount from the electrode deepest position detected by the detection means in a sampling section a predetermined number of times before the current sampling section, and electric discharge machining from the stored movement amount from the electrode deepest position. It is provided with means for judging a machining state, and means for changing a machining condition when the machining state judging means judges that it is unstable.

Further, the control device of the electric discharge machine according to another invention of the present application includes a means for detecting a movement amount from the most advanced electrode position so far in a predetermined sampling section for recognizing a machining state; Describes means for storing the amount of movement from the electrode deepest position detected by the detection means in a sampling section a predetermined number of times before the current sampling section, and a plurality of methods for changing the processing state of the processing condition changing means. Knowledge storage means, and inference means for obtaining a machining state or an amount equivalent thereto by synthesizing a movement amount from the electrode deepest position obtained from the storage means and a plurality of techniques obtained from the knowledge storage means, Means for changing machining conditions in accordance with the degree of stability of the electric discharge machining state obtained from the inference means.

A control device for an electric discharge machine according to another invention of the present application incorporates the machining condition changing means in the inference means, and calculates the machining amount from the stored deepest electrode position and a technique related thereto. An inference means for synthesizing a plurality of obtained results and obtaining a control command value of a processing condition.

[0017]

According to the present invention, knowledge that is effective for controlling the processing conditions is stored in the knowledge storage unit, and the required processing state amount, that is, the amount of movement from the deepest position of the electrode, is detected. Is stored in the situation storage unit several times before the present time, and is obtained by the inference means from the method from the knowledge storage unit and the processing situation amount from the situation storage unit. A plurality of results are combined to execute optimal control of machining conditions.

According to the inference means of the present invention, the electric discharge machining state is unstable when the moving amount from the electrode deepest position is continuously generated or when the moving amount from the electrode deepest position is large instantaneously. When it is determined that the amount of movement from the deepest position of the electrode is increasing, or when the amount of movement from the deepest position of the electrode is large momentarily, it is inferred that the electric discharge machining state is unstable. To work.

Further, the processing condition determining means of the present invention preferentially changes the electrode pulling amount / pulling cycle to a desirable state when the processing state determining means and the inference means determine that the processing is unstable. The operation is performed so as to determine the machining conditions separately from the discharge pause time.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram showing one embodiment of a control device of an electric discharge machine according to the present invention, and FIG. 2 is an overall configuration diagram showing one embodiment of a control device of another electric discharge machine of the present invention. 1 and 2, reference numerals 1 to 7, 21 to 23 are the same as those of the conventional adaptive control device of the electric discharge machine, and therefore, the description thereof is omitted here.

In FIG. 1, reference numeral 41 denotes data of the processing situation amount (movement amount from the deepest position of the electrode) processed by the detection value processing unit 23 several times before the present and processing conditions (shown in the figure). And a failure storage unit 32 for storing whether the electric discharge machining is normal or abnormal based on the data stored in the situation storage unit 41. , 33a are the electrode position control unit 21 and the machining power supply 2 based on the command signal from the abnormality determination unit 32.
2 is a processing condition changing unit that sends a processing command for adaptive control.

In FIG. 2, reference numeral 42 denotes a knowledge storage unit storing a plurality of rules (see FIGS. 5, 6 and 11) for changing the electric discharge machining state, and 43 denotes a machining status stored in the status storage unit 41. The machining conditions or the stability of the electric discharge machining state to achieve the desired electric discharge machining state by synthesizing a plurality of results obtained by the amount and the machining condition and the rules stored in the knowledge storage section 42 in relation to these are combined. The inference unit 33 b to be determined is a machining condition changing unit that sends a machining command for adaptive control to the electrode position control unit 21 and the machining power supply 22 based on the command signal from the inference unit 43.

Embodiment 1 Next, the operation of the apparatus according to the first embodiment of the present invention configured as described above will be described. 1 and 3, the detection value processing unit 23 sets a period between the discharge fall times as a sampling period, and in this sampling period,
The position of the machining electrode 1 obtained from the speed / position detector 7 is 1
Sampling is performed every 5 msec, and position data of the machining electrode 1 is created. The most advanced electrode position Zmin (i) in the sampling section and the most advanced electrode position so far (electrode deepest position, minZ (i)) are calculated and stored from the obtained position data of the processing electrode 1 (step 101). . From the stored data, the movement amount d (i) from the electrode deepest position is calculated by the following equation (step 102). d (i) = Zmin (i) -minZ (i) The calculated movement amount d (i) from the electrode deepest position is stored in the situation storage unit 41. The latest data is stored in the status storage unit 41 as d (i), the data one time before is d (i-1), and the data two times before is d (i-2) (step 103).

The abnormality judging section 32 sets the values of e1 and e2, which are the thresholds of the abnormality judgment. e1 and e2 are usually e1> e2
When the machining electrode 1 suddenly rises greatly, that is, when d (i)> e1, it is determined that the electric discharge machining state is unstable. Also, d (i), d (i-1) and d (i-
If both 2) are larger than e2, it is determined that the electric discharge machining state is unstable.

Based on the command value of the abnormality determination unit 32,
The processing condition changing unit 33a outputs a command to change the processing condition. FIG. 4 shows an example of the operation of the processing condition changing unit 33a. FIG. 4 shows the electrode pull-up amount (J) based on the command value of whether the electric discharge machining state is abnormal and the type of machining state.
FIG. 9 is a flowchart illustrating an example of a procedure for determining an increase / decrease amount of U) and a discharge pause time (OFF). First, when it is determined that the electric discharge machining state is abnormal, the set notches of the currently set electrode descent time (JD), electrode pull-up amount (JU), and discharge pause time (OFF) are stored (step 20).
1). That is, it is determined that the electric discharge machining state is abnormal, and the machining conditions before changing the machining conditions are stored. The notch of the stored electrode descent time (JD) is a, and the notch of the electrode lifting amount (JU) is a. To b, discharge pause time (O
The notch of FF) is c.

For example, when it is determined that the movement amount from the electrode deepest position is unstable and the notch of the currently set electrode descent time (JD) is 1, the electrode pulling amount (J
U) is increased by one notch (step 203, step 2)
05). When it is determined that the movement amount from the electrode deepest position is unstable and the notch of the currently set electrode descent time (JD) is not 1, the electrode descent time (JD)
D) is reduced by one notch (step 203, step 2)
06). If it is determined that the amount of movement is unstable other than the amount of movement from the deepest position of the electrode, the discharge pause time (OFF) is increased by one notch (steps 204 and 207). After determining the electrode descent time (JD), the stability of the electric discharge machining state is determined again.

When it is determined that the notch is stable, the notch of the currently set discharge pause time (OFF) is compared with the stored notch c (step 208). If the comparison results are not equal, the discharge pause time (OFF) is reduced by one notch (step 209). In this way, the discharge pause time (OF
The amount of increase or decrease of F) is determined, and the amount of increase or decrease is output to the machining power supply 22. In step 210, the notch of the currently set electrode pull-up amount (JU) is compared with the stored notch b, and if the comparison result is equal, the flow proceeds to step 212. If the comparison results are not equal, the electrode lifting amount (J
U) is reduced by one notch (step 211). In step 212, the notch of the electrode descent time (JD) is compared with the stored notch a, and if the comparison results are equal, the procedure goes to the end and all steps are completed. If they are not equal, the notch of the electrode fall time (JD) is increased by one notch (step 213). The electrode descent time (J
D), the amount of increase or decrease of the electrode lifting amount (JU) is determined, and the amount of increase or decrease is output to the electrode position control unit 21.

Embodiment 2 FIG. 2 shows another embodiment of the present invention, which realizes highly accurate control (adaptive control close to a skilled worker).
FIG. 5 is an example showing a rule for changing the stability of the electric discharge machining state. FIG. 6 shows the rules expressed in FIG. 5 in a matrix, and is an example showing rules for changing the stability of the electric discharge machining state.

For example, as shown in FIG. 5, the knowledge storage unit 42 in FIG. 2 uses a rule format consisting of an antecedent part (IF) and a consequent part (THEN). The method used is described. For example, in the case of rule A1,
"If the movement amount 1 from the electrode deepest position is almost zero, the movement amount 2 from the electrode deepest position is almost zero, and the movement amount 3 from the electrode deepest position is almost zero, the electric discharge machining state is very stable. . "Is described by a rule using a fuzzy set capable of qualitative expression. At this time, the membership function shown in FIG. 7 is used to handle qualitative and ambiguous expressions such as “almost zero” and “very serious”.

The fuzzy set for "almost zero" is represented by a membership function of "almost zero" as shown in FIG. For example, here, the value of the membership function of 1 is completely belonging to the set,
In addition, 0 indicates that it does not belong to the set at all.

On the other hand, the situation storage unit 41 stores the knowledge storage unit 4
2, a moving amount 1 from the deepest electrode position, a moving amount 2 from the deepest electrode position, and a moving amount 3 from the deepest electrode position are stored. The movement amount 1 from the electrode deepest position is the latest, the movement amount 2 from the electrode deepest position is one time before, and the movement amount 3 from the electrode deepest position is the movement amount from the electrode deepest position detected and calculated two times before. is there. In the situation storage unit 41,
Each time the amount of movement from the electrode deepest position is detected and calculated, the value of the amount of movement 1 is transferred to the amount of movement 2 and the value of the amount of movement 2 is transferred to the amount of movement 3.

The inference unit 43 performs fuzzy inference from the method stored in the knowledge storage unit 42 and the amount of movement from the deepest electrode position stored in the situation storage unit 41 in accordance with the procedures shown in FIGS. The command value of the stability of the electric discharge machining state is determined. In FIG. 8, reference numerals 80 a, 80 b, and 80 c denote detection of “movement amount 1 from the electrode deepest position”, “movement amount 2 from the electrode deepest position”, and “movement amount 3 from the electrode deepest position” stored in the situation storage unit 41. This is a calculated value, and shows the electric discharge machining state in which the machining electrode 1 is rising.

In the fuzzy inference, each rule A1 to A7
In this study, it was examined how much the amounts of movement 1, 2 and 3 from the electrode deepest position, which are the processing state quantities, satisfied the qualitative and ambiguous expression of the antecedent part described by the membership function. In the section, the value of the membership function with the smallest satisfaction level (in Rule A6, the detected operation value 8
0a), the upper limit of the membership function in the consequent part is cut, and the membership functions are combined so as to always have the largest function value among the respective membership functions. Area gravity center position C. G
(5.0) is obtained. This value is a command value for the degree of stability of the electric discharge machining state.

Based on the command value of the degree of stability of the electric discharge machining state, the machining condition changing section 33b outputs a command for changing the machining condition. FIG. 10 shows an example of the operation of the processing condition changing unit 33b. FIG. 10 is a flowchart illustrating an example of a procedure for determining the increase / decrease of the electrode pull-up amount (JU) and the discharge pause time (OFF) based on the obtained degree of stability and the type of the machining state. First, when the degree of stability of the electric discharge machining state is recognized, the currently set electrode descent time (J
D), electrode pull-up amount (JU), discharge pause time (OF)
The setting notch of F) is stored (step 301). That is, it recognizes that the electric discharge machining state is unstable, and stores the machining conditions before changing the machining conditions. The notch of the stored electrode descent time (JD) is a, and the electrode lifting amount (J
The notch of U) is denoted by b, and the notch of the discharge pause time (OFF) is denoted by c. The amount of increase or decrease of the parameter of the processing condition is determined according to the recognized degree of stability f (step 302).
~ Step 310).

For example, when the stability degree f is 3 <f <5 and the movement amount from the deepest position of the electrode is unstable, if the notch of the currently set electrode descent time (JD) is 1, the electrode pulling amount (JU) ) Is increased by one notch (step 30).
5). After determining the electrode descent time (JD), the degree of stability of the electric discharge machining state is recognized again. Here, the degree of stability is 3 <f
In the case of <5, when the movement amount from the electrode deepest position is unstable, the above-described operation is performed. However, when f ≦ 3, the notch of the currently set electrode lifting amount (JU) is stored. The notches b are compared (step 313), and if they are not equal, the electrode pull-up amount (JU) is reduced by one notch (step 314). Thereafter, the electrode lifting amount (J
When U) is equal, the notch of the electrode descent time (JD) is compared with the stored notch a (step 31).
5) If not equal, the notch of the electrode fall time (JD) is increased by one notch (step 316). In this way, the amount of increase / decrease of the electrode descent time (JD) and the electrode lifting amount (JU) is determined and output to the electrode position control unit 21.

The degree of stability f of the electric discharge machining state is 3 <f
In the case of <5, when it is unstable other than the movement amount from the electrode deepest position,
The discharge pause time (OFF) is increased by one notch (step 306). After determining the electric discharge pause time (OFF), the degree of stability of the electric discharge machining state is recognized again, and the degree of stability becomes 3 <f <.
In the case of 5, the above-mentioned operation is performed. However, in the case of f ≦ 3, the notch of the currently set discharge pause time (OFF) is compared with the stored notch c (step 31).
1) If not equal, the discharge pause time (OFF) is reduced by one notch (step 312). In this way, the amount of increase or decrease in the discharge pause time (OFF) is determined, and the machining power supply 2
2 is output.

In the above embodiment, the fuzzy inference in the electric discharge machining state in which the machining electrode 1 is rising has been described.
Here, the electric discharge machining state in which the machining electrode 1 is descending after ascending will be described. In FIG. 9, 90a, 90
b and 90c are “the movement amount 1 from the electrode deepest position” and “the movement amount 2 from the electrode deepest position” stored in the situation storage unit 41.
This is a detection calculation value of “the amount of movement 3 from the electrode deepest position”.
The amount of movement 1, 2, 3 from the deepest position of the electrode satisfies the qualitative and ambiguous expression of the antecedent described by the membership function, and the satisfaction is the smallest in the antecedent. Membership function value (detection operation value 90c for rule A4, detection operation value 90c for rule A2)
a) In the rule A7, the upper limit of the membership function in the consequent part is cut by the detection operation value 90b), and the membership functions are synthesized so that the membership function always has the largest function value among the respective membership functions. C., the area centroid position of the combined membership function G (2.8) is obtained. This value is a command value for the degree of stability of the electric discharge machining state.

Further, in the above embodiment, the degree of stability of the electric discharge machining state is fuzzy inferred, and the machining conditions are changed according to the degree of stability. Although it is not described that the parameter is changed, it can be realized by the same concept as in the above embodiment. FIG. 11 shows an example of a method for changing parameters relating to the processing conditions. FIG.
FIG. 12 illustrates a membership function for a fuzzy set in the method shown in FIG. However, a more sophisticated and complicated adaptive control can be realized by fuzzy inferring the degree of stability of the electric discharge machining state and determining the machining conditions according to the required degree of stability. As described above, by combining a plurality of results to determine the degree of stability of the electric discharge machining state, the degree of stability of the electric discharge machining state is recognized based on a plurality of methods, and the machining conditions are determined based on the recognition. Adaptive control can be realized.

In the above embodiment, the fuzzy set is used in the knowledge storage unit and the fuzzy inference is performed in the inference unit. However, a knowledge expression and an inference method used in other general expert systems may be used. Naturally, it is possible, and the same effects as in the above embodiment can be obtained. In the above embodiment, the antecedent part of the method describes three EDM states and the consequent part describes the stability of one EDM state, but there is nothing to limit these.

In the above embodiment, the sampling interval is set to the discharge fall time. However, there is no problem if the sampling interval is set to a predetermined value. Further, in the above embodiment, the movement amount from the electrode deepest position is calculated by setting the most advanced position in the sampling section as Zmin (i), but the most elevated position in the sampling section may be set as Zmin (i). Since the threshold value of the amount of movement from the deepest position of the electrode and the value of the membership function only slightly change when judging, there is no problem in judging abnormality in electric discharge machining.

[0041]

As described above, according to the present invention, the movement amount from the electrode deepest position, which is the machining state amount several times before the present time, is stored in the state storage unit, and the unstable state of the electric discharge machining state is stored. It is possible to distinguish between the discharge phenomenon in which the machining electrode rises instantaneously and the discharge phenomenon in which the machining electrode rises continuously, so that control corresponding to the discharge phenomenon can be performed and machining can be performed. This has the effect of increasing efficiency.

A rule for changing the stability of the electric discharge machining state according to the moving distance from the electrode deepest position several times before the present time is described in the knowledge storage unit, and this technique and the stored moving distance from the electrode deepest position are described. Thus, the inference unit can determine the degree of stability of the electric discharge machining state. Therefore, the discharge phenomenon in which the machining electrode is rising, the discharge phenomenon in which the machining electrode is falling after rising, and the discharge phenomenon in which the machining electrode rises instantaneously can be accurately grasped. Near machining conditions can be changed. further,
There is an effect that the processing conditions can be automatically controlled by discriminating the electrode descent time, the electrode lifting amount, and the discharge pause time.

Further, in the discharge phenomenon in which the machining electrode rises once and then descends, and in the discharge phenomenon in which the machining electrode rises small momentarily, the electric discharge machining state is not recognized as unstable and the machining conditions are not changed. Therefore, there is also an effect that the electric discharge machining speed is not impaired.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a control device for an electric discharge machine according to the present invention.

FIG. 2 is an overall configuration diagram showing one embodiment of a control device of another electric discharge machine according to the present invention.

FIG. 3 is a flowchart for determining the instability of an electric discharge machining state.

FIG. 4 is a flowchart for calculating an electrode fall time, an electrode lifting amount, and an increase / decrease amount of a pause time.

FIG. 5 is an explanatory diagram in which an example of a method of changing the stability of the electric discharge machining state is described using a rule expressed by a fuzzy set.

FIG. 6 is an explanatory diagram in which an example of a technique for changing the stability of the electric discharge machining state is described using a rule expressed by a fuzzy set.

FIG. 7 is an explanatory diagram describing a membership function for a fuzzy set in FIG. 6;

FIG. 8 is an explanatory diagram showing a process of fuzzy inference in the method of FIG. 6;

FIG. 9 is an explanatory diagram showing a process of fuzzy inference in the method of FIG. 6;

FIG. 10 is a flow chart for obtaining an increase / decrease amount of an electrode descent time, an electrode lifting amount, and a discharge pause time according to the degree of stability.

FIG. 11 is an explanatory diagram in which an example of a technique for changing a machining condition for achieving a desirable electric discharge machining state is described using a rule expressed by a fuzzy set.

12 is an explanatory diagram describing a membership function for the fuzzy set in FIG.

FIG. 13 is a configuration diagram of a conventional adaptive control device for an electric discharge machine.

FIG. 14 is an explanatory diagram showing the movement of a machining electrode.

[Explanation of symbols]

 Reference Signs List 21 electrode position control unit 22 processing power supply 23 detection value processing unit 32 abnormality determination unit 41 situation storage unit 42 knowledge storage unit 43 inference unit 33a processing condition change unit 33b processing condition change unit

Claims (2)

(57) [Claims] 1. An electric discharge machine for performing electric discharge machining by applying a voltage pulse between an electrode and a workpiece, the amount of movement (electrode deepest position) from the most advanced electrode position so far in a predetermined sampling interval. Detecting means for detecting the amount of movement from the electrode deepest position detected by the detecting means in a sampling section a predetermined number of times before the current sampling section; Machining state determining means for determining whether the machining state of the electric discharge machining is stable or unstable from the movement amount from the deepest position, when the machining state determining means determines that the machining state is unstable, preferentially When the electrode is lifted / falls
Electric discharge machine control apparatus being characterized in that a machining condition changing means for between-discharge quiescent time change. 2. An electric discharge machine for performing electric discharge machining by applying a voltage pulse between an electrode and a workpiece, from a position of the most advanced electrode to date in a predetermined sampling section for recognizing a machining state. Detecting means for detecting an amount of movement of the sensor; status storage means for storing the amount of movement from the electrode deepest position detected by the detecting means in a sampling section a predetermined number of times before the current sampling section; and processing condition changing means. A knowledge storage unit describing a plurality of methods for changing a machining state, a movement amount from an electrode deepest position in a current sampling interval stored in the storage unit, and an electrode depth in a sampling interval a predetermined number of times before the current time. Compared with the movement amount from the position, the stored movement amount from the electrode deepest position is larger than a predetermined threshold value. In this case, when it is determined that the moving amount from the electrode deepest position in the current sampling section is decreasing, it is determined that the electric discharge machining state is stable, and when it is determined that it is increasing, electric discharge machining is being performed. Inference means for judging that the state is unstable; and when the inference means infers that the machining state is unstable, the electrode lifting amount, the electrode descent time, and the discharge are given priority.
Electric discharge machine control apparatus being characterized in that a machining condition changing means to change the pause time.