JPH1043951A - Wire electric discharge machining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the contact state between a wire electrode and a workpiece without being influenced by the frequency of an electric discharge machining power source by containing a power source independent from a working power source device, and providing a contact detecting device for detecting the contact between the wire electrode and the workpiece. SOLUTION: This device has a DC power source 101 for supplying a voltage for detecting the contact between electrodes of a contact detecting circuit 100. A contact detection output signal C is H level or L level when a signal L is H level, and the output signal E of an AND circuit 113 outputs H level only when the electrodes are in contact. The latched value of the counter outputs Q0-Q3 of a decimal counter 202 in a contact state detecting device 200 shows the contact ratio, and the contact state between poles in a contact ratio detecting device 204 is detected. The detected contact state and distance between electrodes are read in a NC control device 11 to control the feeding speed of a wire electrode 1 and a workpiece 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire electric discharge machine.

[0002]

2. Description of the Related Art FIG. 9 is a diagram showing the overall structure of a wire electric discharge machine. In the figure, 1 is a wire electrode, 2 is a workpiece, 3 is a wire guide for guiding the wire electrode 1 in the upper and lower parts, 4 is a table on which the workpiece 2 is placed, and 5a and 5b are An X-axis and Y-axis drive motor for relatively moving the workpiece 2; 6 an axis drive controller for controlling the X-axis and Y-axis drive motors 5a and 5b; 7 a machining gap between the wire electrode 1 and the workpiece 2 , A power supply for supplying an output of the power supply device for electric discharge 7 to the wire electrode 1, a power supply control device for machining 9 for controlling a switching operation of the power supply device 7 for electric discharge machining Numeral 10 is a gap voltage detecting device for detecting a machining voltage between the gaps, 11 is an NC control device for sending an axis movement command and machining condition parameters to the axis drive control device 6 and the machining power supply control device 9, and 12 is an NC program. It is a non.

FIG. 10 is a view showing an example of a power supply device for machining and an inter-electrode voltage detecting device. Reference numeral 700 denotes a power supply circuit for electric discharge machining corresponding to 7 in FIG. 701, a switching element 702 that is turned on and off by the processing power supply control device 9, and a limiting resistor 703 that limits the value of the current flowing between the electrodes. Reference numeral 1000 denotes a gap voltage detection device corresponding to 10 in FIG. 9 and includes a voltage rectification diode 1001, voltage division resistors 1002 and 1003, a voltage smoothing capacitor 1004, and a gap voltage detection circuit 1005. I have. Reference numeral 13 denotes an impedance existing in the power supply path.

Next, the operation will be described. NC device 11
Is input with machining path information and machining electrical condition parameters from the NC program 12 or an operation panel (not shown). The input machining electric condition parameters are output to the machining power control device 9, and the machining power control device 9 generates a drive signal having a predetermined current peak, pulse width, and pause time based on these parameters. The processing power supply device 7 is controlled. The processing power supply 7 is driven by the drive signal, and a predetermined current pulse is supplied to the processing gap between the wire electrode 1 held by the wire guide 3 above and below the workpiece 2 and the workpiece 2. At the same time, electric discharge machining is performed by generally supplying water or an aqueous machining fluid to the machining gap.

FIG. 11 is a diagram showing a waveform between the poles.
(A) shows the processing voltage, and (b) shows the processing current. After the switching element 702 in FIG. 10 is turned on, the machining gap voltage increases to the voltage E1 of the DC power supply 701 as shown in (a) until the discharge starts, and the machining gap voltage decreases to the arc potential E2 with the start of the discharge. . At this time, the voltage detection circuit 10 of FIG. 9 detects that the machining gap voltage has dropped to the arc potential, judges that the electric discharge has started, outputs the electric discharge to the machining power supply control device 9, and outputs the electric power to the machining power supply control device 9 as shown in FIG. T
(During ON) The switching element 702 is kept ON, and a processing current determined by the voltage E1 of the DC power supply 701 and the constant of the limiting resistor 703 is supplied to the processing gap. After that, the switching element 702 is turned off and the predetermined time (TO
The above operation, such as the OFF time being continued only during the FF and the switching element 702 being turned on again, is repeated to generate a discharge between the wire electrode and the workpiece.

At the same time, the NC unit 11 outputs a positioning command to the drive control unit 6 based on the processing path information, and controls the X-axis drive motor 5a and the Y-axis drive motor 5b to control the positioning of the table 4. By doing so, the workpiece is processed into a desired shape. The voltage between the electrodes is half-wave rectified by the voltage rectifying diode 1001, divided by the voltage dividing resistors 1002 and 1003, smoothed and averaged by the voltage smoothing capacitor 1004, and is converted by the electrode voltage detecting circuit 1005. Is detected. As described above, the gap voltage detecting apparatus 1000 determines a gap state such as open, discharge, or short circuit based on the value of the gap voltage.
In order to perform more stable electric discharge machining, the wire electrode 1 and the workpiece 2 are relatively moved so as to have a predetermined voltage.

[0007]

The conventional wire electric discharge machine is constituted as described above, and electric discharge machining is performed once per one.
This is performed by accumulating the generated discharges. Therefore, in order to improve the machining speed, it is necessary to increase the frequency of the discharge pulse. However, if the discharge frequency is increased, the impedance 13 of the power supply path increases. For example, the value of the impedance 13 is Z, the resistance of the limiting resistor 703 is R, the voltage of the DC power supply 701 is E1, and the voltage between the electrodes is E1. Eg, the voltage between aa ′ in FIG. 9 is (2Z
/ (R + 2Z)) * E1 + (1-2Z / (R + 2Z))
* Eg, the increase in impedance Z is
The result is that the gap voltage detection differs depending on the machining state, which has a significant effect on the gap voltage detection.

For example, in the case of low-frequency electric discharge machining, the impedance 13 of the power supply path can be neglected, and the voltage between a and a 'becomes Eg (inter-electrode voltage) regardless of the state of the inter-electrode gap. However, in high-frequency electric discharge machining, the impedance 13 of the power supply path cannot be ignored. If the gap is open, the voltage between a and a 'becomes E1, but even if a short circuit occurs, (2Z / (R + 2Z)) * E1 and the voltage are present, making it difficult to detect a short circuit. Further, the detected value of the voltage between the electrodes during discharge is not the relative value of the actual voltage between the electrodes, and there is a problem that the relative movement between the wire electrode 1 and the workpiece 2 cannot be appropriately performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems.
It is an object of the present invention to accurately detect a state between poles and perform stable electric discharge machining regardless of the frequency of a power supply device for electric discharge machining.

[0010]

According to a first aspect of the present invention, there is provided a wire electric discharge machine which applies a voltage from a machining power supply to a gap formed between a wire electrode and a workpiece to generate electric discharge, and In a wire electric discharge machine for processing the workpiece by relatively moving the wire electrode and the workpiece, a power supply independent of the machining power supply is built in, and the wire electrode and the workpiece are And a contact state detecting device for outputting contact state information between the wire electrode and the workpiece using an output signal of the contact detecting device.

A wire electric discharge machine according to a second aspect of the present invention generates a discharge by applying a voltage from a machining power supply to a gap formed between a wire electrode and a workpiece.
In a wire-cut electric discharge machine for processing the workpiece by relatively moving the wire electrode and the workpiece, a power supply independent of the machining power supply is built in, and the wire electrode and the workpiece are built in. A contact detection device that detects contact with the device, a contact state detection device that outputs contact state information between the wire electrode and the workpiece using an output signal of the contact detection device, and using the contact state information. The apparatus further includes a gap distance calculating means for calculating a distance between the wire electrode and the workpiece.

A wire electric discharge machine according to a third aspect of the present invention generates a discharge by applying a voltage from a machining power supply to a gap formed between a wire electrode and a workpiece.
In a wire-cut electric discharge machine for processing the workpiece by relatively moving the wire electrode and the workpiece, a power supply independent of the machining power supply is built in, and the wire electrode and the workpiece are built in. A contact detection device that detects a contact with the workpiece, a contact state detection device that outputs contact state information between the wire electrode and the workpiece using an output signal of the contact detection device, and an output of the contact state detection device. And a control device for controlling a processing feed speed so that a contact state between the wire electrode and the workpiece becomes a predetermined state based on a signal.

A wire electric discharge machine according to a fourth aspect of the present invention is the wire electric discharge machine according to any one of the first to third aspects, wherein the contact state information between the wire electrode and the workpiece output by the contact state detecting device is provided. This is the contact rate.

A wire electric discharge machine according to a fifth aspect of the present invention is the wire electric discharge machine according to the second aspect of the present invention, wherein the inter-electrode distance calculating means calculates at least one of the thickness of the workpiece and the tension of the wire electrode as a parameter. It is something to do.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing details of a control circuit of the wire electric discharge machine according to the first embodiment of the present invention. 8 and 9
The description of the same parts as those of the conventional example shown in FIG.

In FIG. 1, reference numeral 100 denotes a contact detection circuit for detecting contact between poles; 101, a DC power supply for supplying a voltage for detecting contact between the poles of the contact detection circuit 100;
Is a switching element for turning on and off the detection circuit, 103
Is a resistor for suppressing the circuit current of the detection circuit, 104 is a photocoupler composed of an input photodiode 104a and an output phototransistor 104b, 105 is a diode for protecting the photocoupler 104, and 106 is a current flowing through the photocoupler 104 The resistor,
107 is a diode for preventing the gap machining current from flowing back to the contact detection circuit, and 108 is a photocoupler 104
, An AND circuit for judging and receiving the output of the photocoupler 104 as a contact, 110 a contact detection sampling pulse generating circuit for controlling the switching element 102, and 111 for driving the switching element 102 Drive circuit, 112 is NO
A pulse delay circuit configured to output a detection count pulse composed of T circuits 112a / 112b, an AND circuit 112d, and a capacitor 112c, and an AND circuit 113 configured to output a contact detection count pulse.

Reference numeral 200 denotes a contact state detecting device for detecting a contact state between the wire electrode and the workpiece, and 201 denotes a decimal counter for counting a detection count pulse.
02 is a decimal counter that counts a contact detection count pulse, 203 is a latch circuit that latches the counter output of the decimal counter 202, 204 is a contact ratio detection device that determines the contact state from the output of the latch circuit, and 205 is NOT
This is a pulse delay circuit for resetting the count values of the decimal counters 201 and 202 each including a circuit 205a / 205b and a capacitor 205c.

Next, the operation of the first embodiment will be described with reference to the drawings. 2 and 3 are diagrams showing an example of the output signal of each section in FIG. 1, and FIG. 2 also shows a contact / non-contact state between the poles. 2 and 3, a signal A is a contact detection sampling pulse of the contact detection sampling pulse generation circuit 110, and a signal C is an AND circuit 109.
, A signal D is a detection count pulse output from the pulse delay circuit 112, and a signal E is an AND circuit 11
The contact detection pulse 3 and the signals F to I are a decimal counter 20
2, a counter output Q0 to Q3, a signal J is a carry output of the decimal counter 201, and a signal K is a counter reset pulse output from the pulse delay circuit 205 and resetting the count values of the decimal counters 201 and 202.

Here, the signal A is a pulse for performing contact detection sampling at a frequency (for example, several hundred Hz to several tens kHz) at which the impedance 13 of the power supply path can be ignored.
Is turned on and off at the timing of the signal A, and when the switching element 102 is on, the voltage of the DC power supply 101 is supplied to the wire electrode 1 and the workpiece 2 via the resistor 103 / diode 107 / power supply 8. .

Here, if the electrode between the wire electrode 1 and the workpiece 2 is in contact, the resistance of the resistor 106 is sufficiently larger than the contact resistance, so that the photodiode 104a on the input side of the photocoupler 104 , Almost no current flows, the phototransistor 104b on the output side of the photocoupler 104 is in a high impedance state, and the contact detection output signal B is set to the H level by the pull-up resistor 108.

When the gap between the wire electrode 1 and the workpiece 2 is in a non-contact state, the current of the DC power source is supplied to the resistor 103/10.
6, a current flows through the photodiode 104a, which is the input side of the photocoupler 104, and the phototransistor 104b, which is the output side of the photocoupler 104, is turned on, so that the contact detection output signal B becomes L level.

When the switching element 102 is turned off, no current flows through the photodiode which is the input of the photocoupler 104, as in the case where the gap between the wire electrode 1 and the electrode of the workpiece 2 is in contact. The output signal B becomes H level by the pull-up resistor 108.

Next, as shown in FIG.
At 12, a NOT circuit 112a / 112b and a delay circuit composed of a capacitor 112c are used.
The signal A is a delay signal like the signal L with a delay time determined by the internal resistance of the capacitor 2a / 112b and the capacitance of the capacitor 112c.
The signal is input to the D circuit 112d, and a pulse delay signal such as the signal D in FIG. 3 is output. Further, the contact detection output signal C is at the H level or the L level when the signal L is at the H level, and the output signal E of the AND circuit 113 outputs the H level only when the gap is in contact as shown in FIG.

That is, the output signal D of the contact detection device 100
And the output signal E is a contact detection sampling pulse signal A.
Is output, an output signal D is output as a contact detection sampling count pulse, and a contact detection pulse signal E is output if there is a contact between the electrodes.

Next, the signal J of the carry output of the decimal counter 201 is output when the counter value is 10, becomes H level, latches the latch circuit 203, and outputs the signal K via the pulse delay circuit 205 to output 10. The binary counters 201 and 202 are reset. In this manner, the counter outputs Q0 to Q3 of the decimal counter 202 can continuously count the contact state between the poles.

Here, the contact state between the electrodes is shown in FIGS. 4 and 5, but since a non-rigid wire is used for the machining electrode, as shown by the shaded portion in FIG. The wire electrode vibrates intricately due to the repulsive force of electrical discharge machining. FIG. 4A shows a state in which the electrode distance between the wire electrode and the workpiece is far from the vibration of the wire electrode, and no contact occurs between the wire electrode and the workpiece even during electric discharge machining. (B)
In this case, the distance between the poles becomes narrower, a contact state between the wire electrode and the workpiece starts to occur, and contact / non-contact is repeated,
The smaller the distance between the poles, the greater the number of contacts. When the distance between the electrodes is further reduced, the wire electrode and the workpiece are always in a contact state, that is, a short-circuit state, as shown in FIG.

As shown in FIGS. 5A and 5B, the contact ratio between the wire electrode and the workpiece varies depending on the distance between the poles. For example, the distance between the poles is large, and the larger the contact rate, the smaller the distance between the poles. Therefore, the distance between the poles can be determined by knowing the contact rate during electric discharge machining.

Further, as shown in FIG. 5 (A), the distance between the electrodes for the same contact ratio differs depending on the plate thickness of the workpiece. You can see that it is narrower and wider if it is thinner. Also,
As shown in FIG. 5 (B), the inter-electrode distance for the same contact rate differs depending on the tension of the wire electrode, and the inter-electrode distance is narrow if the tension of the wire electrode is high and wide if the tension is low even at the same contact rate. Recognize. That is, if the thickness of the workpiece and the tension of the wire electrode are known, the distance between the electrodes can be accurately determined from the contact ratio.

In this embodiment, the decimal counter 202
The latched values of the counter outputs Q0 to Q3 indicate the contact ratio, the contact state detecting device 204 can detect the contact state between the poles, and the contact distance can be known and detected based on the contact state. The contact state and the distance between the poles are taken into the NC controller 11 so that the processing feed speed of the wire electrode 1 and the workpiece 2 can be controlled.

For example, the machining feed speed in the NC controller 11 can be controlled by a feedback system as shown in FIG. In the figure, reference numeral 301 denotes a transfer function G1 for calculating a machining feed rate based on a deviation between a contact rate target value and an actual contact rate; 302, a transfer function G2 for calculating a gap distance based on the machining feed rate; The transfer function G3 calculates the contact rate based on the distance, and corresponds to the contact state detection device according to the present embodiment.

Here, the distance between the poles of the control system changes depending on the machining state, which is added as a disturbance. If the machining proceeds more than the machining feed speed, the gap between the poles becomes wider, and the contact rate decreases, and the contact rate decreases. Because the deviation of the detected contact rate increases,
The machining feed speed increases. Further, if the processing feed speed is faster than the processing, the gap distance becomes narrower, the contact rate becomes higher, and the deviation between the target contact rate and the detected contact rate becomes smaller, so that the processing feed rate becomes slower. In this way, if the target value of the contact ratio is set, the processing feed speed can be easily controlled even if the processing state changes.

The transfer function G3 in FIG. 6 is shown in FIG.
As apparent from (B), the thickness changes with the plate thickness of the workpiece and the wire tension as parameters. FIG. 7 shows this in a table, and shows which transfer function should be used for the four values of the workpiece thickness and the four values of the wire tension. In practice, these are stored in advance in a memory in the control device or in the contact state detection device, and are automatically selected when the plate thickness and the wire tension are given.

Embodiment 2 FIG. In the first embodiment, only one decimal counter is used as shown in FIG.
By cascade-connecting a plurality of counter outputs, the counter outputs Q0 to Q3 at the final stage of the decimal counter can be converted to an averaged value. For example, when three decimal counters are used, when the count of 201c is 1000, the contact count of 202c is latched. Therefore, the parameter is 1000 in the first embodiment, compared to 10 in the first embodiment. I can do it.

Further, in Embodiments 1 and 2, a parameter using the contact rate is shown as a parameter representing the contact state. However, the present invention is not limited to this, and other parameters representing the contact state, for example, Obviously, the number of contact pulses within a certain time may be used.

[0035]

The wire electric discharge machine according to the first aspect of the present invention generates a discharge by applying a voltage from a machining power supply to a gap formed between a wire electrode and a workpiece.
2. Description of the Related Art A wire electric discharge machine for processing a workpiece by relatively moving a wire electrode and the workpiece includes a built-in power supply independent of a machining power supply device and detects contact between the wire electrode and the workpiece. Since it has a contact detection device and a contact state detection device that outputs contact state information between the wire electrode and the workpiece using an output signal of the contact detection device, the contact detection device is affected by the frequency of the power supply for electric discharge machining. It is possible to detect the contact state between the wire electrode and the workpiece.

The wire electric discharge machine according to the second aspect of the present invention generates a discharge by applying a voltage from a machining power supply to a gap formed between a wire electrode and a workpiece.
2. Description of the Related Art A wire electric discharge machine for processing a workpiece by relatively moving a wire electrode and the workpiece includes a built-in power supply independent of a machining power supply device and detects contact between the wire electrode and the workpiece. A contact detector, a contact state detector that outputs contact state information between the wire electrode and the workpiece using an output signal of the contact detector, and a distance between the wire electrode and the workpiece using the contact state information. Between the wire electrode and the workpiece without being affected by the frequency of the power source for electric discharge machining, thereby detecting the contact distance between the wire electrode and the workpiece. To know.

A wire electric discharge machine according to a third aspect of the present invention generates a discharge by applying a voltage from a machining power supply to a gap formed between a wire electrode and a workpiece.
2. Description of the Related Art A wire electric discharge machine for processing a workpiece by relatively moving a wire electrode and the workpiece includes a built-in power supply independent of a machining power supply device and detects contact between the wire electrode and the workpiece. A contact detection device, a contact state detection device that outputs contact state information between the wire electrode and the workpiece using an output signal of the contact detection device, and a wire electrode and the workpiece based on the output signal of the contact state detection device. A control device for controlling the machining feed speed so that the contact state with the object is in a predetermined state is provided, so that the machining feed speed suitable for the gap state can be realized regardless of the frequency of the power supply for electric discharge machining. Enable.

A wire electric discharge machine according to a fourth aspect of the present invention is the wire electric discharge machine according to any one of the first to third aspects, wherein the information on the contact state between the wire electrode and the workpiece output by the contact state detector is output. Since the contact rate is used, it is possible to represent the contact state with a single data, and control is facilitated.

The wire electric discharge machine according to a fifth aspect of the present invention is the wire electric discharge machine according to the second aspect of the present invention, wherein the inter-electrode distance calculating means calculates at least one of the thickness of the workpiece and the tension of the wire electrode as a parameter. As a result, the distance between the wire electrode and the workpiece can be kept constant irrespective of the thickness of the workpiece and the tension of the wire electrode, enabling stable high-precision wire electric discharge machining. I do.

[Brief description of the drawings]

FIG. 1 is a control circuit diagram of a wire electric discharge machine according to a first embodiment.

FIG. 2 is a timing chart showing an operation of a control circuit output signal of the wire electric discharge machine according to the first embodiment.

FIG. 3 is a timing chart illustrating an operation of a control circuit output signal of the wire electric discharge machine according to the first embodiment.

FIG. 4 is a diagram illustrating a contact state between a wire electrode and a pole of the wire electric discharge machine according to the first embodiment.

FIG. 5 is a diagram showing the relationship between the contact ratio and the distance between the electrodes of the wire electric discharge machine according to the first embodiment.

FIG. 6 is a block diagram of a control system of the wire electric discharge machine according to the first embodiment.

FIG. 7 is a diagram illustrating a transfer function that changes with a plate thickness and a tension as parameters.

FIG. 8 is a control circuit connection diagram of the second embodiment.

FIG. 9 is a configuration diagram of the entire wire electric discharge machine.

FIG. 10 is a circuit diagram of a conventional inter-electrode voltage detection device.

FIG. 11 is a diagram showing an inter-electrode waveform.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wire electrode, 2 ... Workpiece, 3 ... Wire guide, 7 ... Power supply for processing, 8 ... Power supply, 9
..Power supply control device for processing, 11 ... NC control device, 1
3 ... inductance, 100 ... contact detection device,
200 contact state detection device

Claims (5)

[Claims] 1. A processing power supply device applies a voltage to a gap formed between a wire electrode and a workpiece to generate a discharge, and relatively moves the wire electrode and the workpiece to perform the processing. In a wire-cut electric discharge machining apparatus for machining an object, a contact detection device that incorporates a power supply independent of the machining power supply device and detects contact between the wire electrode and the workpiece, A wire electric discharge machine comprising: a contact state detecting device that outputs contact state information between the wire electrode and the workpiece using an output signal. 2. A processing power supply device applies a voltage to a gap formed between the wire electrode and the workpiece to generate a discharge, and relatively moves the wire electrode and the workpiece to perform the processing. In a wire-cut electric discharge machining apparatus for machining an object, a contact detection device that incorporates a power supply independent of the machining power supply device and detects contact between the wire electrode and the workpiece, A contact state detection device that outputs contact state information between the wire electrode and the workpiece using an output signal; and a gap distance that determines a distance between the wire electrode and the workpiece using the contact state information. A wire electric discharge machine comprising: a calculating means. 3. A process is performed by applying a voltage from a power supply device for processing to a gap formed between a wire electrode and a workpiece to generate a discharge, and moving the wire electrode and the workpiece relative to each other. In a wire-cut electric discharge machining apparatus for machining an object, a contact detection device that incorporates a power supply independent of the machining power supply device and detects contact between the wire electrode and the workpiece, A contact state detection device that outputs contact state information between the wire electrode and the workpiece using an output signal; and a contact state between the wire electrode and the workpiece based on an output signal of the contact state detection device. And a control device for controlling the machining feed rate so as to be in a predetermined state. 4. The wire electric discharge machine according to claim 1, wherein the contact state information between the wire electrode and the workpiece output by the contact state detecting device is a contact rate. Wire electric discharge machine. 5. The wire electric discharge machine according to claim 2, wherein the distance calculation means calculates at least one of the thickness of the workpiece and the tension of the wire electrode as a parameter. Processing equipment.