JPH0757445B2 - Discharge analysis device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to an electric discharge analysis apparatus for displaying a state such as a gap 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, electric discharge is generated between the wire electrode and the workpiece. However, the workpiece is processed by this 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, although the above-mentioned methods can detect abnormal discharge, their reliability is low, and much less the amount of the gap between the wire electrode and the work piece can be detected. For this reason, it is not known whether the gap amount is large or small, and the discharge energy at that time is also large or small. Therefore, it is difficult to optimally control the gap amount and the discharge energy.

(Problems to be Solved by the Invention) As described above, the gap amount and the discharge energy between the wire electrode and the workpiece cannot be detected, and it becomes difficult to optimally control the gap amount and the discharge energy. ing.

Therefore, it is an object of the present invention to provide a discharge analysis device capable of graphically displaying a gap amount between a discharge electrode and a workpiece and discharge energy.

[Configuration of the Invention] The present invention is a detector for detecting a discharge voltage and a discharge current to a workpiece, and a detection signal from the detector at a predetermined sampling period in a plurality of signal sampling periods at regular intervals. A signal sampling means for digitally converting and fetching, a discharge data creating means for creating discharge data composed of at least discharge voltage value data and discharge current pulse width data in each discharge from each detection signal sampled by the signal sampling means, 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 this comparison result, and a histogram is created for discharge voltage data excluding this abnormal discharge data. Create the normal discharge data and the low voltage side of this normal discharge data based on the frequency distribution of this created histogram Discharge classification means for classifying into transient discharge data exhibiting different distribution modes, and summing a plurality of signal sampling periods to obtain a signal sampling period total value and corresponding to normal discharge data determined by the discharge classifying means. The discharge current pulse width data is summed to obtain the discharge current pulse width sum value, and the ratio of the discharge current pulse width sum value to the signal sampling period sum value is calculated as the pulse generation interval, and then the discharge electrode is determined based on this pulse generation interval. Based on the gap amount calculation means for obtaining the gap amount with the workpiece, and the machining limit value determined by the gap amount calculated by this gap amount calculation means and the number of abnormal discharge data and the number of transient discharge data A machining energy range calculation means for obtaining a machining energy range showing a discharge state of machining chips between the discharge electrode and the workpiece, and the discharge electrode and the workpiece. As well as the graphic display at intervals corresponding to the gap amount obtained by 置算 detecting means,
An electric discharge analysis apparatus for achieving the above object, comprising a display for displaying an electric discharge machining state by graphically displaying a machining energy range on the basis of an electric discharge electrode which is graphically displayed.

(Operation) With the provision of such means, when either or both of the discharge voltage and the discharge current are detected, this detection signal is digitally converted and taken in every signal sampling period at a predetermined interval. It is created as discharge data such as discharge voltage.

When the discharge data is created in this way, the gap amount between the discharge electrode and the work piece is obtained based on the discharge data, and machining according to the discharge status of machining scraps between the discharge electrode and the work piece is performed. Energy range is required.

Then, the discharge electrode and the workpiece are graphically displayed on the display at intervals corresponding to the gap amount, and together with this, the processing energy range moves as a range indication frame according to the discharge status of the processing chips and is displayed. It is displayed as a graphic on.

(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 analysis device. The workpiece 2 is infiltrated into the processing tank 1. This work piece 2
Wire electrodes 3 are arranged at predetermined intervals.
The wire electrode 3 is 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
Is 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 and a display drive unit 20 are connected. The timing controller 17 controls the signal acquisition timing in the A / D converters 13 and 14. Further, a display device 21 is connected to the display drive section 20 to drive the display device 21 for display. The ROM 19 stores a discharge analysis program that determines discharge data such as a discharge start time, a discharge end time, a current peak value, and a pulse interval from the captured discharge voltage and discharge current, and determines the quality of the discharge from the discharge data. There is. In addition, the ROM 19 has an A / D for the timing controller 17.
A signal sampling timing program for the converters 13 and 14 is stored. However, this signal sampling timing program causes the A / D converters 13 and 14 to digitally convert the voltage detection signal and the current detection signal into 8-bit signals at the same time, for example, at every xns during the signal sampling period at regular intervals, and then once During the sampling period, for example, data of 1024 to 65536B will be collected. In addition, the intervals of the respective signal acquisition periods come at regular intervals ΔH. Therefore, the A / D converters 13, 14, the CPU 16, the timing controller 17, and the ROM 19 constitute a signal sampling means. Further, the ROM 19 stores a discharge data creation program and a machining state display program.
As a result, the CPU 16 has the respective functions of the signal sampling means 16-1, the discharge data creating means 16-2 and the processing state display means 16-3 as shown in FIG. The signal sampling means 16-1 has a part of the functions of the signal sampling means as described above. Discharge data creating means 16-2
Has a function of creating discharge data composed 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.

Further, the processing state display means 16-3 is the discharge data creating means 16-
The positional relationship between the wire electrode 3 and the workpiece 2 is obtained from the discharge data created in 2 and machining from the wire electrode 3 is performed according to the discharge status of machining waste between the wire electrode 3 and the workpiece 3. It has a function of obtaining an energy range, and graphically displaying the positional relationship between the wire electrode 3 and the workpiece 2 and the processing energy range on the display 21. Specifically, it comprises a gap amount calculating means 16-4 and a processing energy calculating means 16-5.

The gap amount calculation means 16-4 calculates the gap amount F between the wire electrode 3 and the workpiece 2 from the number of normal discharges. Specifically, for example, in 10 signal acquisition periods, the total period Et of the current pulse width of the normal discharge obtained as described below is calculated, and the total period H ₀ of the same signal acquisition period is calculated. Ratio, that is, the pulse generation interval Q Q = H ₀ / Et (1) for normal discharge, and then the gap amount F F = a · W · f (E, V, number of generated) / Q (2) Is to be calculated.

Here, a is a constant that is experimentally obtained. Also, 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), V (discharge voltage) and "generation". It is a function determined by the number "(sum of normal discharge data number described later and transient discharge data number described later in all signal sampling periods).

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

Further, the processing energy range calculation means 16-5 is used for the wire electrode 3
The processing energy range De corresponding to the discharge status of the processing waste between the workpiece 3 and the workpiece 3 is obtained. In this case, the processing energy range De does not indicate an absolute value, but indicates a range to which the electric discharge between the wire electrode 3 and the workpiece 3 is normally performed. .

That is, as shown in FIG. 5, when the range designating 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
As shown in the figure, when the range designating frame K of the machining energy range De is inside the work piece 3, it indicates the "abnormal discharge state". Such a processing energy range De is expressed by the following equation (3).

De = F + f (Xs) (3) Here, F is the gap amount. Further, f (Xs) is a machining limit value, which is a function determined by Xs (sum of abnormal discharge data number described later and transient discharge data number 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 3).

That is, according to this formula (3), when the processing dust starts to increase in the discharge gap and the transient discharge is added to the normal discharge, the processing energy range De also becomes large, and as shown in FIG. The frame K is in a state of being close to the workpiece 3.

Further, when the machining scraps drastically increase in the discharge gap, electrical conduction occurs, and abnormal electric discharge starts, the machining energy range De rapidly increases, and the tip K of the machining energy range De becomes the workpiece 3 as shown in FIG. Be inside. Therefore, the processing energy range De
The electric discharge machining state can be determined depending on where the range designation frame K is.

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 object 2 and the wire electrode 3. The workpiece 2 is processed by the energy of this pulse discharge.

In this state, the voltage detector 7 detects the discharge voltage of the pulse 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 discharge current of the pulse that has flowed to the circuit 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, the A / D converters 13 and 14 are both controlled by the timing controller 17 to digitally convert the voltage detection signal and the current detection signal, respectively. In other words, each A / D converter 13, 14 has a third
As shown in the figure, each signal sampling period H ₁ and H ₂ at regular intervals ΔH
.., the voltage detection signal and the current detection signal are simultaneously digitally converted into 8 bits and fetched, for example, every xns. 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 captured in _one signal sampling period H ₁ , H ₂ ... are temporarily stored in the memory in each A / D converter 13 and 14, respectively, and are collected in each signal sampling period. After the passage of H ₁ , H ₂ … by CPU16
It is moved to RAM 18 and stored.

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 12 times ends, the discharge data creating means 16 of the CPU 16
-2 obtains respective waveforms of discharge voltage and discharge current from each digital voltage detection signal and digital current signal,
Occurrence number "1" in order of pulse discharge generation from these waveforms
"2" ... "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 that the discharge start points a1, a2 ... An, the discharge end points b1, B2 ... Bn, the discharge voltage c1, C2 ... Cn, the current peak values d1, d2 in each pulse discharge.
… Dn, current pulse width e1, e2… en, discharge energy f1, f2… f
The discharge data D consisting of parameters such as n and pulse intervals g1, g2 ... Gn are obtained, tabulated and stored in the RAM 18.

Next, the position calculation means 16-4 of the CPU 16 sets the discharge limit voltage set in advance and the discharge voltages c1 and c in the 12 signal sampling periods.
2 ... cn is detected to detect a discharge voltage having a level lower than the discharge limit voltage, for example, c2 as an arc discharge pulse or a short circuit which is an abnormal discharge, and the abnormal discharge data is deleted from the discharge data D to generate a normal discharge. Only number data. Next, the gap amount calculating means 16-4 determines the current pulse width of normal discharge.
The total period Et of e1, e3, e4 ... en is calculated, and the total period H _{0 of 12} signal sampling periods H ₁ , H ₂ , ... H ₁₂ is calculated, and from these total periods Et, H ₀ , the above (1) The pulse generation interval Q is calculated according to the equation, and then the gap amount F between the wire electrode 3 and the workpiece 2 is calculated according to the equation (2). The gap amount F is located on the screen of the display 21.

The processing energy range calculation means 16-5 obtains the sum Xs of the number of transient discharge data and the number of abnormal discharge data over the 12 signal acquisition periods. Then, the above-described machining limit value f (Xs) is calculated based on the obtained sum Xs of the transient discharge data number and the abnormal discharge data number, and the machining limit value f (Xs) is calculated according to the above equation (3). The processing energy range De is calculated by adding the gap amount F.

Then, the normal discharge data, the transient discharge data and the abnormal discharge data are classified by the gap amount calculating means 16-4 of the CPU 16 as follows.

First, as described above, abnormal discharge data and non-abnormal discharge data are classified. Next, the discharge voltage is extracted from the discharge data D that is not abnormal, and the histogram shown in FIG. 4 is created.

In this histogram, the normal distribution Q ₁ showing normal discharge and
A normal distribution Q ₂ showing a transient discharge located on the low voltage side of the normal distribution Q ₁ appears.

Therefore, the gap amount calculation means 16-4 classifies the discharge data belonging to the normal distribution Q ₁ as the normal discharge data, and calculates the normal distribution Q ₂
The discharge data that belongs to is classified as transient discharge data. Then, the CPU 16 graphically displays the gap amount F and the processing energy range De on the display 21. That is, FIGS. 5 to 7 show such display examples, and FIG. 5 shows a state in which the wire electrode 3 is too far from the machined surface of the workpiece 2 and in this case, the discharge energy is Afford. Further, FIG. 6 shows that the respective positions of the range designating frame K and the surface of the workpiece 2 are substantially coincident with each other to be in the best machining state. Further, FIG. 7 shows a state in which the wire electrode 3 is in contact with the workpiece 2 or the processing is unreasonable.

As described above, in the above-described embodiment, the discharge voltage and the discharge current are taken in to create discharge data, the positional relationship between the wire electrode 3 and the workpiece 2 is determined from the discharge data, and the wire electrode 3 and the workpiece are processed. Since the machining energy range De corresponding to the discharge status of machining scraps between the workpiece 2 and the workpiece 2 is obtained and displayed graphically, the current traveling direction of the wire electrode 3 and the workpiece 2 during the electric discharge machining is displayed. It can be visually recognized whether the gap amount F is large or small, and whether the processing energy range De at that time is also large or small. As a result, an image can be obtained based on the ratio of the quality of the discharged state of the processing waste to the normal processing energy range. Among these, the amount of processing waste between the wire electrode 3 and the workpiece 2 can be known from the processing energy range De. That is, if the processing energy range De is wide, the amount of processing waste is small, and if the processing energy range De is narrow, the amount of processing waste is large. Therefore, it is possible to optimally control the gap amount F and the processing energy from the display results of the gap amount F and the processing energy range De.

The present invention is not limited to the above-described embodiment, and may be modified 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, the discharge peak and the discharge energies f1, f2 ...
It is also possible to create a histogram of and classify from the normal distribution. Further, the display of efficiency is not limited to the bar display. In addition, this equipment is not limited to wire electric discharge machining equipment, but can also 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] As described in detail above, according to the present invention, the gap amount between the discharge electrode and the workpiece and the processing energy range can be displayed graphically, and the discharge electrode and the workpiece can be displayed from this processing energy range. It is possible to provide an electric discharge analysis device capable of visually visualizing and grasping the discharge status of machining waste during the period and capable of optimally controlling the machining energy range.

[Brief description of drawings]

1 to 7 are views for explaining an embodiment of an electric discharge analysis apparatus according to the present invention. FIG. 1 is a configuration diagram, FIG. 2 is a functional block diagram, and FIG. 3 is electric discharge machining. FIG. 4 is a diagram showing the display contents of the state, FIG. 4 is a diagram for explaining the action of classification of abnormal discharge, and FIGS. 5 to 7 are diagrams showing display examples of the electric discharge machining state. 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 ... Machining status display means, 16-4 ... Position calculation Means, 16-5 ... Machining energy calculation means, 17 ... Timing controller,
18 …… RAM, 19 …… ROM, 20 …… Display drive, 21 …… Display unit.

Claims (1)

[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 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 at least discharge voltage data and discharge current pulse width data at each discharge occurrence based on the detection signal collected by the signal collecting means. (D) 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 the discharge voltage excluding this abnormal discharge data is detected. A histogram is created for the data, and it is classified into normal discharge data and transient discharge data exhibiting different distribution modes on the low voltage side of this normal discharge data based on the frequency distribution of the created histogram, and in the normal discharge data. The corresponding discharge current pulse width data is summed to obtain the discharge current pulse width sum value, and the ratio of this discharge current pulse width sum value to the signal sampling period is obtained as the pulse generation interval, and then based on this pulse generation interval. Gap amount calculation means for obtaining a gap amount between the discharge electrode and the workpiece. (E) The discharge electrode and the workpiece are separated from each other on the basis of the gap amount calculated by the gap amount calculation means and the machining limit value determined by the number of the abnormal discharge data and the number of the transient discharge data. Machining energy range calculation means for obtaining a machining energy range that indicates the discharge status of machining chips during the period. (F) The discharge electrode and the workpiece are graphically displayed at intervals corresponding to the gap amount obtained by the gap amount calculating means, and the machining energy range is displayed by the discharge electrode graphically displayed. A display for displaying the electric discharge machining state by displaying a graphic as a reference.