JPH0761570B2 - Discharge state analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a discharge state analysis apparatus for analyzing a discharge state in electric discharge machining.

(Prior Art) For example, electric discharge machining includes wire electric discharge machining and die-sinking electric discharge machining. Of these, for example, wire electric discharge machining will be explained by arranging wire electrodes at predetermined intervals with respect to a workpiece. The workpiece and the wire electrode are soaked into the machining tank, and a DC voltage is applied between the workpiece and the wire electrode in this state. Then, for example, when the wire electrode is brought close to the workpiece and the gap amount becomes a predetermined amount, pulse discharge is generated between the wire electrode and the workpiece.
However, the work piece is processed by the pulse discharge energy.

In such wire electric discharge machining, the quality of the machining state is judged. This judgment is made based on whether the electric discharge state is normal or abnormal. This judgment is made by the following method. . That is, a worker visually checks the discharge column and judges the discharge state by experience and intuition based on the brightness of the discharge column.

The worker hears the sound of the discharge, and judges the discharge state from the sound of the discharge by experience and intuition.

If the wire electric discharge machine is equipped with an oscilloscope, the oscilloscope displays, for example, the waveforms of the discharge voltage and the discharge current between the wire electrode and the workpiece, and the discharge state is judged from these discharge voltage and discharge current. .

If a standard for the quality of the discharge state is set in advance in the wire electric discharge machine, the discharge state is determined according to this standard.

However, among the above methods, the method and the method do not quantitatively determine the discharge state, but the determination results vary. In the method (1), the frequency band of the oscilloscope is slower than that of discharging, and the discharging voltage and discharging current cannot be displayed in real time. Furthermore, since the occurrence of discharge is random and the discharge voltage and discharge current are not retained,
The waveforms of the discharge voltage and the discharge current displayed on the oscilloscope are difficult to understand at any time, and it is difficult to quantitatively judge from the waveforms. In the method (1), the quality standard is set by each manufacturer, for example, and cannot be applied to all discharge state determinations. In the further method, each manufacturer takes measures to avoid abnormalities and prevents various disconnections, but on the contrary, it is not possible to achieve the highest efficiency processing, so for example, always improve the efficiency to 60-70% and keep the processing state. It is not accurate enough to detect. Therefore, even if the abnormal discharge is detected, the reliability of the detection of the abnormal discharge is low. However, by monitoring the discharge status, the conditions under which discharge is possible,
For example, it is difficult to properly control the electric discharge machining even if feedback is made to the moving speed of the wire electrode or the flow velocity of the machining liquid.

(Problems to be Solved by the Invention) As described above, the reliability of the abnormal discharge detection is low, and the discharge state cannot be grasped accurately.

Therefore, it is an object of the present invention to provide a discharge state analysis device capable of quantitatively grasping the discharge state.

[Configuration of the Invention] (Means for Solving the Problem) The present invention provides a detector for detecting a discharge voltage and a discharge current between a workpiece and a discharge electrode, and a detection signal from the detector to a predetermined value. A signal sampling means for digitally converting the signal over a signal sampling period, and a discharge composed of discharge voltage data and discharge current pulse width data for each discharge occurrence based on the discharge voltage detection signal and the discharge current detection signal sampled by the signal sampling means. Discharge data creating means for creating data,
Histogram creating means for inputting the discharge data and creating a histogram, and comparing the discharge voltage data created by the discharge data creating means with a preset discharge limit voltage, and abnormal discharge data based on the comparison result. And a discharge voltage data excluding abnormal discharge data is created a histogram by the histogram creating means, on the basis of the frequency distribution of the created histogram normal discharge data and on the low voltage side of the normal discharge data. A discharge current pulse is obtained by summing discharge classification means for classifying into transient discharge data indicating different distribution modes and discharge current pulse width data corresponding to normal discharge data determined by the discharge classification means over the signal sampling period. Calculate the total width value, and calculate the ratio of this total discharge current pulse width value to the signal sampling period. Electrostatic calculated as efficiency, a discharge state analyzing apparatus comprising; and a determining discharge analyzing means electric discharge machining conditions based on the calculated result.

Further, the present invention provides a detector for detecting a discharge voltage and a discharge current between a work piece and a discharge electrode, and a signal sampling means for digitally capturing a detection signal from the detector for a predetermined signal sampling period. Discharge data generating means for generating discharge data consisting of discharge voltage data and discharge current pulse width data for each discharge occurrence based on the discharge voltage detection signal and the discharge current detection signal sampled by the signal sampling means; Histogram creating means for inputting data and creating a histogram, and comparing the discharge voltage data created by the discharge data creating means with a preset discharge limit voltage, and detecting abnormal discharge data based on the comparison result. At the same time, a histogram is created by the histogram creating means for the discharge voltage data excluding the abnormal discharge data. Based on the frequency distribution of the created histogram, discharge classification means for classifying normal discharge data and transient discharge data showing different distribution modes on the low voltage side of the normal discharge data, and the discharge classifying means. The discharge current pulse width data corresponding to the normal discharge data is summed over the signal sampling period to obtain a discharge current pulse width total value, and the ratio of the discharge current pulse width total value and the signal sampling period is calculated as discharge efficiency. And, the ratio of the total number of the discharge voltage value data to the sum of the number of the abnormal discharge data and the number of the transient discharge data is calculated as the stability, and the electric discharge machining state is calculated based on the discharge efficiency and the stability. And a discharge analysis means for determining.

(Operation) The present invention sums the discharge current pulse width data corresponding to the normal discharge data determined by the discharge classification means over the signal sampling period to obtain the discharge current pulse width total value, and the discharge current pulse width total value And the ratio of the signal sampling period is calculated as the discharge efficiency, and the ratio of the total number of the discharge voltage value data to the sum of the number of the abnormal discharge data and the number of the transient discharge data is calculated as the stability, and Since the electric discharge machining state is determined based on the electric discharge efficiency and the stability, the electric discharge machining state can be accurately and quickly determined. Therefore, based on this determination result, it becomes possible to stably maintain the electric discharge machining condition in an optimum state for a long time, and it is possible to greatly contribute to the improvement of productivity and machining quality.

(Example) Hereinafter, one example of the present invention will be described with reference to the drawings.

FIG. 1 is an overall configuration diagram of a discharge state analysis device applied to wire machining discharge. The workpiece 2 is infiltrated into the processing tank 1. Wire electrodes 3 are arranged on the workpiece 2 at predetermined intervals. In addition, this wire electrode 3
Are supported by the upper wire guide body 4 and a lower wire guide body (not shown). A DC power supply 6 is connected between the work piece 2 and the wire electrode 3 via a discharge control circuit 5 to form a discharge circuit. In this case, the DC power supply 6 has its positive electrode connected to the workpiece 2. A voltage detector 7 is connected in parallel to the DC power supply 6 and a current detector 8 is connected in series to the DC power supply 6 in this discharge circuit.

On the other hand, 10 is the analyzer body, and the analyzer body 10
Are provided with attenuators (ATT) 11 and 12, and the voltage detector 7 is connected to one attenuator 11 and the current detector 8 is connected to the other attenuator 12. Attenuators 11 and 12 are connected to respective A / D (analog / digital) converters 13 and 14 each having a built-in memory, and these A / D converters 13 and 14 are connected to a CPU (central processing unit) via a bus 15. Device) 16 is connected. This CPU16 has a bus 15
Through the timing controller 17, RAM (random
An access memory) 18, a ROM (read only memory) 19, a display drive unit 20, a printer drive unit 21, and an input operation unit 22 such as a keyboard are connected. The timing controller 17 controls the signal acquisition timing in the A / D converters 13 and 14. Also, the display drive unit 20 has a CR
A display device 23 such as a T display is connected, and a printer 24 is connected to the printer drive unit 21.

A / D converter in timing controller 17 in ROM19
The signal acquisition timing program for 3 and 14 is stored. However, the A / D converters 13 and 14 based on this signal sampling timing program digitally convert the voltage detection signal and the current detection signal into 8 bits simultaneously at the same time, for example, every xns in the signal sampling period at constant intervals ΔH. For example, data of 1024 to 65536B will be collected in the signal collection period of once. Therefore, the A / D converters 13, 14, the CPU 16, the timing controller 17, and the ROM 19 constitute a signal sampling means.

The ROM 19 also stores a discharge data creation program, a discharge classification program, a discharge analysis program, and a history creation program. However, by executing these programs, the CPU 16 causes the signal sampling means 16 as shown in FIG.
-1, discharge data creating means 16-2, discharge classifying means 16-
3. It has the respective functions of the discharge analyzing means 16-4 and the history creating means 16-5. The signal sampling means 16-1 has a part of the functions of the signal sampling means as described above.

The discharge data creating means 16-2 has a function of creating discharge data consisting of parameters such as discharge voltage and discharge current in each discharge from the digital voltage detection signal and the digital current detection signal sampled by the signal sampling means. .

The discharge classifying means 16-3 has a function of classifying the discharge into three types of abnormal discharge, transient discharge and normal discharge based on the discharge voltage value in the discharge data. Here, the abnormal discharge is an arc discharge pulse and a short circuit, and the transient discharge is generated in a state where a considerable amount of machining waste exists between the workpiece 2 and the wire electrode 3. The normal discharge is generated in a state where there is no processing waste between the work piece 2 and the wire electrode 3.

The discharge analysis means 16-4 includes the abnormal discharge, the transient discharge and the normal discharge classified by the discharge classification means 16-3 and the efficiency and stability of the discharge machining based on the discharge data created by the discharge data creating means 16-2. In addition to calculating the surface roughness, the discharge gap image function that graphically displays the state of the discharge energy between the work piece 2 and the wire electrode 3, and further functions such as wire breakage prediction judgment and machining condition instruction I have. Specifically, the histogram creating means 16-6 and the analysis calculating means 16-7 are provided. The histogram creating means 16-6 has a function of creating each histogram of the discharge voltage, discharge current, discharge energy, etc. of each discharge in the discharge data, and for example having a function of obtaining the mode value from the histogram of the discharge energy. The means 16-7 has a function of calculating the efficiency, stability, surface roughness, etc. of the electric discharge machining from the above-mentioned electric discharge data and the mode value obtained from each histogram.

The history creating means 16-5 has a function of receiving the efficiency and stability calculated by the discharge analyzing means 16-4 and creating history data thereof and printing it.

Further, in the RAM 18, as shown in FIG. 3, adjustment data of each parameter such as a discharge pulse width for improving machining conditions such as speed in electric discharge machining is stored. Here, the parameters are pulse width La, pulse interval Lb, discharge current Ld,
The discharge voltage Le and the abnormality detection level Lf are set, and the machining conditions are set to improve speed, improve roughness, and further improve accuracy. And, for example, if the speed is increased, the adjustment data is such that the pulse width La is widened, the pulse interval Lb is narrowed, the discharge current Ld is further increased, and the discharge voltage Le is increased.
Is increased and the abnormality detection level Lf is decreased.

Then, when the processing condition is input from the input operation unit 22, the CPU 16 sends each parameter of the processing condition and the adjustment data to RA.
The adjustment data read out from M18 is up "↑" and down "↓", for example, the pulse width La "wide" is displayed on the display device 23 with up "↑". In addition to the above functions, the CPU 16 has a function of discriminating between rough machining and finish machining, a function of switching the measurement range, and the like.

Next, the operation of the apparatus configured as described above will be described with reference to FIG.

A DC voltage is applied between the work piece 2 and the wire electrode 3 from the DC power supply 6 through the discharge control circuit 5, and when the gap amount between the work piece 2 and the wire electrode 3 reaches a predetermined amount in this state, the work piece is processed. A pulse discharge is generated between the workpiece 2 and the wire electrode 3, and the workpiece 2 is processed by the energy of this pulse discharge.

In this state, the voltage detector 7 detects the pulse discharge voltage between the workpiece 2 and the wire electrode 3 and outputs the voltage detection signal, and the current detector 8 outputs the voltage from the workpiece 2 to the wire electrode 3. The flowing pulse discharge current is detected and the current detection signal is output. The voltage detection signal and the current detection signal are respectively attenuated to a level that can be easily processed by the attenuators 11 and 12 and input to the A / D converters 13 and 14. At this time, each A / D converter 1
Both 3 and 14 are controlled by the timing controller 17 to digitally convert the voltage detection signal and the current detection signal, respectively. That is, the A / D converters 13 and 14 have the signal sampling periods H ₁ , H _2, ...
At the same time, for example, the voltage detection signal at the same time for each xns,
Each current detection signal is digitally converted into 8 bits and taken in. As a result, data of, for example, 1024 to 65536B is captured in _one signal sampling period, for example, the signal sampling period H ₁ . In this way, the digital voltage detection signal and the digital current signal are acquired in one signal sampling period, respectively.
It is temporarily stored in the memory in the A / D converters 13 and 14, and is transferred to and stored in the RAM 18 by the CPU 16 after the elapse of each signal sampling period H ₁ , H ₂ ...

In this way, the digital voltage detection signal and the digital current signal are fetched and stored in the RAM 18, and, for example, when the signal sampling period of 10 times ends, the discharge data creating means 16 of the CPU 16
-2 obtains respective waveforms of the discharge voltage and the discharge current as shown in FIG. 5 from the respective digital voltage detection signals and the digital current signals, and the generation numbers "1", "2" ... "From these waveforms in the order of discharge occurrence. N "is added. However, when no voltage is applied and no discharge is generated between the workpiece 2 and the wire electrode 3 and no discharge current flows, no generation number is given. That is, the numbers are attached only when the discharge occurs. Then, the CPU 16 determines, from these waveforms, the discharge start time points a1, a2 ... an, the discharge end time points b1, b2 ... bn, the discharge voltage c1, c2 ... cn, and the current peak value in each discharge.
d1, d2 ... dn, current pulse width e1, e2 ... en, discharge energy f
Fn ... fn, pulse intervals g1, g2 ... gn, and other discharge data D are obtained, and this discharge data D is stored in the RAM 18
The table is stored in the table.

When the discharge data D is obtained in this way, the CPU 16 determines the machining state. In this case, the CPU 16 reads the current peak value d1 from the digital current detection signal stored in the RAM 18,
This current peak value d1 is compared with a preset threshold value. If the current peak value d1 is larger than the threshold value by this comparison, the CPU 16 determines that the electric discharge machining currently being performed is rough machining, and if the current peak value d1 is smaller than the threshold value, the CPU 16 Judges that the electric discharge machining is the finishing machining.

Next, the CPU 16 sets the measurement range. That is, CPU16
A current peak and a voltage peak are obtained from each digital voltage detection signal and digital current signal stored in the RAM 18. Next, the CPU 16 determines whether or not the current peak value is a predetermined ratio, for example, 40% or more with respect to the current range of the measurement range, for example 0 to 1000A. Here, when the current peak value is 150 A as shown in FIG. 6, this current peak value is 0 to the current range.
Since it is 40% or less with respect to 1000 A, the CPU 16 lowers the measurement range by one range and sets the current range to 0 as shown in FIG.
Change to a measurement range of ~ 400A. Again, the CPU 16 determines whether the current peak value is 40% or more for the current range 0 to 400 A of the measurement range. In this case as well, the current peak value is 40% or less for the current range of 0 to 400 A, so the CPU 16 further reduces the measurement range by one range and changes to the measurement range of the current range of 0 to 200 A as shown in FIG. To do. Thus, the current peak value is 40% or more with respect to the current range of 0 to 200A, and the measurement range of the current range is set to 0 to 200A. Next, the CPU 16 sets the measurement range for voltage in the same way as the measurement range for the current range is set.

Next, the CPU 16 determines whether the electric discharge machining state determined above is rough machining or finish machining.
As shown in Fig. 9, the sampling cycle of the D converters 13 and 14 is set to xns.
Set the sampling cycle at to yns as shown in the figure.

After that, if the electrical discharge machining state is rough machining, the CPU 16 digitally converts the current detection signal into 8 bits in the measurement range of the current range 0 to 200 A in each signal sampling period H ₁ , H _2, ... And the voltage detection signal is changed and captured in the set measurement range. Then, when the signal sampling periods H ₁ , H _2, ... Come several times, for example, 10 times, the discharge data creating means 16-2 creates the discharge data D again and stores it in the RAM 18.

Next, the discharge classifying means 16-3 compares the preset discharge limit voltage with each discharge voltage c1, c2 ... Cn, and discharges a discharge voltage whose level is lower than the discharge limit voltage, for example, c2, an arc discharge pulse which is an abnormal discharge. And a short circuit. When an abnormal discharge is detected in this way, the occurrence number of this abnormal discharge c2 is "2".
Discharge start a2, discharge end b2, discharge voltage c2, current peak value
Each data of d2 is deleted from the table. In this case, the occurrence number “2” is moved to the abnormal discharge table formed in the RAM 18.

Next, the histogram creating means 16-6 extracts the discharge voltages c1, c3, c4 ... Cn-1, cn from the discharge data D in which the abnormal discharge has been erased, and creates a histogram of the discharge voltage shown in FIG. Two histogram groups Q ₁ and Q ₂ appear in the histogram created in this way. Here, the histogram group Q ₁ shows the discharge voltage in a state where the space between the workpiece 2 and the wire electrode 3 is sufficiently cleaned by the flow of the machining liquid and the machining waste is removed, and in this state The discharge voltage shows the histogram group Q _{1 because the} work piece 2 and the wire electrode 3 due to the fluctuation of the discharge resistance value due to the slight residual machining waste between the work piece 2 and the wire electrode 3 or the vibration of the wire electrode 3 It is caused by the variation in the amount of the gap between the and. On the other hand, in the histogram group Q ₂ , a considerable amount of machining waste remains between the workpiece 2 and the wire electrode 3, and due to this machining waste, the resistance value between the gaps becomes small and discharge occurs even if the discharge voltage is low. It shows a transient discharge. Accordingly, the discharge classifying unit 16-3 classifies the histogram group Q ₁ as normal discharge and classifies the histogram group Q ₂ as transient discharge.

Next, the histogram creating means 16-6 creates each histogram of each discharge voltage, discharge current, discharge energy, etc. in the discharge data D, and finds the mode value from the histogram of the discharge energy, for example.

Then, the analysis calculation means 16-7 calculates the efficiency and the stability. First, the efficiency calculating operation will be described. The analysis calculating means 16-7 uses the current pulse widths e1, e3, e4 ...
The total period Et of en is calculated, the total period H ₁ + H ₂ + ... + H ₁₂ of ₁₂ signal sampling periods is calculated, and the ratio of these total periods, that is, the duty ratio Q of the discharge current waveform is calculated as the efficiency.

When _{E = Et / (H 1 +} H 2 + ... + H 12) ...... (1) In this way the efficiency Q is calculated, analysis calculation means 16-7
Sends the efficiency Q to the display drive unit 20 and causes the display device 23 to display the efficiency Q. FIG. 11 is a display example of the efficiency Q, which is displayed as a bar.

Further, the analysis calculating means 16-7 obtains the number Na of abnormal discharges and the number Nt of transient discharges, and calculates the ratio of these numbers to the total number N of discharges as the stability Se. That is, Se = (Na + Nt) / N (2). By the way, this stability Se represents whether the workpiece 2 and the wire electrode 3 are too close to each other. That is, for example, when the work piece 2 and the wire electrode 3 are too close to each other without the work piece, or when the work piece is present between the work piece 2 and the wire electrode 3, This is because the resistivity decreases and abnormal discharge and transient discharge occur. Then, the analysis calculation means 16-7 sends the stability Se to the display drive section 20 and displays it on the display device 23 as a bar. In this case, the display of the stability Se is divided into three degrees, that is, low rate, good and unstable (danger) as shown in FIG.

Next, the discharge calculating means 16-7 obtains a histogram based on the discharge energies f1, f2 ... fn stored in the RAM 18, and obtains the most frequent discharge energy E from the obtained histogram. Then, since the calculated discharge energy E and the surface roughness Rm are in a proportional relationship, the surface roughness Rm is calculated using the following equation.

Rm = βE Here, β is a proportional constant, which is determined experimentally and is determined by the material of the workpiece and the electrical discharge machining conditions. Then, the calculated surface roughness Rm is displayed by the display device 23.

The analysis calculation means 16-7 also displays the discharge gap image on the display device 23. That is, the analysis calculation unit 16-7 of the signal sampling period H _1, total duration Et and the signal sampling period H ₁ of the current pulse width of the normal discharge in H ₂ ..., H ₂ ... The total period H ₀ of the 10 times The ratio, that is, the pulse generation interval Q _T Q _T = H ₀ / Et …… (3), is calculated, and then the gap amount F F = a ・ W ・ f (E) / Q …… (4) is calculated. calculate. Here, a is a constant that is experimentally obtained. W is a drawing constant at the time of graphic output described later. Further, f (E, V, number of occurrences) is E (processing energy required for one discharge pulse, an integrated value of the product of discharge voltage and discharge current during one discharge pulse period) and V (discharge voltage)
And "Number of occurrences" (sum of the number of normal discharge data described later and the number of transient discharge data described later in the entire signal sampling period)
Is a function determined by.

This function shows a characteristic that the gap amount F tends to increase with a decrease in the “occurrence number” when the number of abnormal discharge data described later is constant, and also tends to decrease with an increase in E. It is formulated with consideration. Further, Q is the pulse generation interval.

Further, the electric discharge analysis means 16-4 is provided with a machining energy range according to the discharge state of machining waste between the wire electrode 3 and the workpiece 3.
It is a request for De. In this case, the processing energy range De does not indicate an absolute value, but the wire electrode 3
This is for indicating to what extent the electric discharge between the workpiece 3 and the workpiece 3 is normally performed.

That is, as shown in FIG. 12, when the range indication frame K of the machining energy range De with the wire electrode 3 as the reference position is in front of the workpiece 3, the "normal discharge state" is indicated and the machining energy range is shown. When the De range designating frame K is inside the workpiece 3, it indicates an "abnormal discharge state". Such a processing energy range De is expressed by the following equation (5).

De = F + f (Xs) (5) Here, F is the gap amount. Also, f (Xs) is
It is a machining limit value and is a function determined by Xs (the sum of the number of abnormal discharge data described later and the number of transient discharge data described later).

Generally, in the case of normal discharge only, the next discharge occurs after the insulating state is sufficiently recovered and the processing waste is almost completely discharged. Since this normal discharge is not greatly affected by the atmosphere of the discharge gap (the discharge state of the processing waste), it is possible to form the discharge in the form closest to the set conditions.

However, if a part of the processing waste remains, the insulation is not completely restored, so that the specific resistance becomes low and the next discharge occurs at a low current and a low voltage. This is a transient discharge. This transient discharge is different from the abnormal discharge that is in an electrically conductive (arc discharge or short-circuit) state, but discharge machining is performed, but its machining capability is small. The generation of such a transient discharge depends on the insulation recovery state after the normal discharge has occurred.

By the way, the abnormal discharge tends to occur after the gap amount F is considerably narrowed, and the atmosphere of the discharge gap (the discharge state of the processing waste) in such a case cannot be judged only by the gap amount F. Therefore, in the gap amount F,
By adding the machining limit value f (Xs) determined by the number of abnormal discharge data and the number of transient discharge data, a formula formulated to display the atmosphere of the discharge gap (discharged state of machining chips) is 5).

That is, according to this equation (5), when the machining waste begins to increase in the discharge gap and the transient discharge is added to the normal discharge, the machining energy range De also increases, and the range indication frame K of the machining energy range De is the workpiece. The state becomes close to 3.

Further, when machining scraps are drastically increased in the discharge gap to cause electrical conduction and abnormal discharge begins, the machining energy range De rapidly increases, and the tip K of the machining energy range De is inside the workpiece 3. Therefore, the electric discharge machining state can be determined depending on where the range designation frame K of the machining energy range De is.

Also, the analysis calculation means 16-7 makes a wire / wire breakage prediction determination. That is, the analysis calculation means 16-7 causes the discharge data D
The discharge energies f1, f2, f3, ... Fn are extracted from and sequentially compared with the discharge energy threshold. For example, if the discharge energy f3 is larger than the discharge energy threshold value by this comparison, it is determined that there is a high risk of disconnection of the wire electrode 3, and this is displayed on the display device 22. FIG. 13 is a display example of a notification of the danger of wire breakage, in which “Wire breakage danger !!” is displayed.

The analysis calculation means 16-7 compares the stability Se with the approach degree threshold value. As a result of this comparison, if the stability Se is larger than the approaching degree threshold value, the analysis calculation means 16-7 determines that there is a high risk of disconnection of the wire electrode 3, and this fact is shown in FIG. Is displayed on the display device 23. In this case, the display device 23 displays only "wire disconnection danger !!" and "wire approaching".

Further, the analysis calculating means 16-7, based on the discharge start points a1, a2 ... An and the discharge end points b1, b2 ... bn in the discharge data D stored in the RAM 18, determines the total number of signal sampling periods. The abnormal discharge occurrence time Δta (the time interval between the discharge start time and the discharge end time of the abnormal discharge is calculated for all the abnormal discharges generated in all the signal sampling periods and summed) is calculated. Then, the ratio of the total signal collection period ΔT to the calculated abnormal discharge occurrence time Δta is calculated as the contact rate A by the following equation.

A = Δta / ΔT Then, the contact rate A is compared with the contact rate threshold rate. The contact rate A represents the degree of contact of the wire electrode 3 with the workpiece 2. The contact rate A is compared with the contact rate threshold rate. If the contact rate A is larger than the contact rate threshold rate, It is judged that there is a high risk that the wire electrode 3 will be broken, and this fact is displayed on the display device 22 as shown in FIG.

Next, the operation of the history creating means 16-5 will be described. The history creating means 16-5 stores the efficiency Q, the stability Se and the contact rate A, which are sequentially obtained, in the RAM 18 as history data, and the efficiency Q, the stability Se and the contact rate A are shown in FIG. To print out with printer 24. FIG. 14 shows an example of printout, showing efficiency Q and stability Se.
Is shown as the history data by the length of the horizontal bar, and the contact rate A is shown as the history data by a numerical value. In addition, "E" is attached together with the contact rate A,
This is because the wire electrode 3 is judged to have a high risk of disconnection. Data such as the number of discharges generated, discharge energy and discharge current are also printed out.

By the way, if the machining conditions deteriorate during the electric discharge machining, no electric discharge occurs between the workpiece 2 and the wire electrode 3, and the electric discharge machining cannot be performed. In such a case, the discharge voltage does not appear, and the CPU 16 causes the internal timer to operate from this time. When the discharge voltage appears again, the CPU 16 stops the operation of the internal timer, calculates the non-discharge period G from the count value, and sends it to the printer drive unit 21. As a result, the non-discharge period G is printed out with no signal time, for example, 60 s. The internal timer operates even when the discharge voltage does not appear when the workpiece 2 is replaced, and counts the time, and the period required for the replacement is printed out.

On the other hand, when the input operation unit 22 receives an instruction for processing conditions for speed improvement, the CPU 16 reads each adjustment data shown in FIG. 3 from the RAM 18 and converts these adjustment data into up “↑” and down “↓”. Further, the converted adjustment data and each parameter are associated with each other and sent to the display drive unit 20. Thus, on the display device 23, each adjustment data for speed improvement as shown in FIG. 15 is displayed by up "↑" and down "↓". It should be noted that although the speed improvement and the roughness improvement are displayed in the figure, only one of them is actually displayed.

As described above, in the above-described embodiment, the discharge voltage and the discharge current are detected, and the discharge data D is created by capturing the discharge voltage and the discharge current at a predetermined sampling period for each signal sampling period. Since the classification is performed and the efficiency of the electrical discharge machining and the like are calculated from the classified result and the electrical discharge data D, the efficiency of the electrical discharge machining is Q,
In addition to being able to quantitatively determine the stability and surface roughness, the image of the discharge gap can be displayed graphically and the processing state can be visually grasped. Further, the risk of wire breakage of the wire electrode 3 can be predicted, and the optimum processing conditions can be adjusted by displaying the processing condition instruction. Further, since the history data is printed out, the unmachined portion can be easily identified even in the unmanned electric discharge machining.

The present invention is not limited to the above-described embodiment, but may be modified within the scope without departing from the spirit of the invention. For example, although the abnormal discharge is classified according to the discharge voltage in the above embodiment, it may be classified according to the discharge peak value.
Further, the display of efficiency and the like is not limited to the bar display. Furthermore, this equipment is not limited to wire electric discharge machining equipment, but it can be used for die-sinking electric discharge machining, electrolytic machining, and by changing the sampling range of voltage and current signals, welding machines, laser applied equipment, lighting equipment, sputtering equipment, PVD and CVD equipment. It can also be applied to electric discharge application equipment such as plasma processing equipment. Among them, the sputtering apparatus can adjust the flow rate of the discharge medium by detecting the discharge state.

EFFECTS OF THE INVENTION The present invention quantifies the electrical discharge machining state using various parameters and determines the electrical discharge machining state based on these parameters, so the electrical discharge machining state can be accurately and quickly determined in real time. be able to. Therefore, based on this determination result, it becomes possible to stably maintain the electric discharge machining condition in an optimum state for a long time, and it is possible to greatly contribute to the improvement of productivity and machining quality.

[Brief description of drawings]

1 to 15 are views for explaining an embodiment of the discharge state analyzing apparatus according to the present invention. FIG. 1 is a configuration diagram, FIG. 2 is a functional block diagram, and FIG. Schematic diagram of condition data, FIG. 4 is a schematic diagram showing a signal sampling period, FIG.
6 is a waveform diagram of discharge voltage and discharge current, FIGS. 6 to 8 are diagrams for explaining the measurement range switching action, FIG. 9 is a diagram showing a sampling period, and FIG. 10 is a diagram showing the action of discharge classification. Fig. 11 is a diagram for showing a processing state display example,
FIG. 12 is a diagram showing a display example of a discharge gap image, FIG.
FIG. 14 is a diagram showing a display example of wire breakage prediction, FIG. 14 is a diagram showing a printout example of history data, and FIG. 15 is a diagram showing a display example of processing condition instructions. 1 ... Machining tank, 2 ... Workpiece, 3 ... Wire electrode, 4
...... Upper wire guide body, 5 …… Discharge control circuit, 6 ……
DC power supply, 7 ... voltage detector, 8 ... current detector, 10 ...
… Analysis device body, 11,12 …… Attenuator, 13,14 …… A /
D converter, 15 ... bus, 16 ... CPU, 16-1 ... signal sampling means, 16-2 ... discharge data creating means, 16-3 ... discharge classifying means, 16-4 ... discharge analyzing means , 16-5 ... History creating means, 16-6 ... Histogram creating means, 16-7 ...
Analytical calculation means, 17 ... Timing controller, 18 ...
RAM, 19 ... ROM, 20 ... Display drive unit, 21 ... Printer drive unit, 22 ... Input operation unit, 23 ... Display device, 24 ... Printer.

Claims (2)

[Claims] 1. An electric discharge machining state comprising the following constitutions (a) to (f), wherein a voltage is periodically applied between a workpiece and an electric discharge electrode to perform electric discharge machining of the workpiece. Discharge state analysis device for analysis. (A) A detector that detects a discharge voltage and a discharge current between the workpiece and the discharge electrode. (B) Signal sampling means for digitally capturing the detection signal from the detector for a predetermined signal sampling period. (C) Discharge data creating means for creating discharge data consisting of discharge voltage data and discharge current pulse width data for each discharge occurrence based on the discharge voltage detection signal and the discharge current detection signal sampled by the signal sampling means. (D) Histogram creating means for inputting the discharge data and creating a histogram. (E) The discharge voltage data created by the discharge data creating means is compared with a preset discharge limit voltage, abnormal discharge data is detected based on the comparison result, and discharge in which the abnormal discharge data is excluded A histogram is created for the voltage data by the histogram creating means, and is classified into normal discharge data and transient discharge data showing different distribution modes on the low voltage side of the normal discharge data based on the frequency distribution of the created histogram. Discharge classification means. (F) The discharge current pulse width data corresponding to the normal discharge data determined by the discharge classification means is summed over the signal sampling period to obtain the discharge current pulse width sum value, and the discharge current pulse width sum value and the sum An electric discharge analysis means for calculating a ratio with a signal sampling period as electric discharge efficiency and determining an electric discharge machining state based on the calculation result. 2. An electric discharge machining state comprising the following constitutions (a) to (f), wherein a voltage is periodically applied between a workpiece and an electric discharge electrode to discharge the workpiece. Discharge state analysis device for analysis. (A) A detector that detects a discharge voltage and a discharge current between the workpiece and the discharge electrode. (B) Signal sampling means for digitally capturing the detection signal from the detector for a predetermined signal sampling period. (C) Discharge data creating means for creating discharge data consisting of discharge voltage data and discharge current pulse width data for each discharge occurrence based on the discharge voltage detection signal and the discharge current detection signal sampled by the signal sampling means. (D) Histogram creating means for inputting the discharge data and creating a histogram. (E) The discharge voltage data created by the discharge data creating means is compared with a preset discharge limit voltage, abnormal discharge data is detected based on the comparison result, and discharge in which the abnormal discharge data is excluded A histogram is created for the voltage data by the histogram creating means, and is classified into normal discharge data and transient discharge data showing different distribution modes on the low voltage side of the normal discharge data based on the frequency distribution of the created histogram. Discharge classification means. (F) The discharge current pulse width data corresponding to the normal discharge data determined by the discharge classification means is summed over the signal sampling period to obtain the discharge current pulse width sum value, and the discharge current pulse width sum value and the sum The ratio with the signal sampling period is calculated as the discharge efficiency, and the ratio of the total number of the discharge voltage value data to the sum of the number of the abnormal discharge data and the number of the transient discharge data is calculated as the stability. Electric discharge analysis means for judging the electric discharge machining state based on the efficiency and the stability.