JPH06277949A - Wire cut discharge machining device - Google Patents

Abstract

PURPOSE:To provide a wire cut discharge machining device which can prevent a hunting condition where a short circuit and retreat control are repeated. CONSTITUTION:When a short circuit between a wire electrode and a material to be worked is detected, a moving command from an NC program practicing device 20 is interrupted temporarily, and a command (a command of which stopping time is longer than stopping time before a short circuit) to change stopping time of pulse-like voltage supplied between the wire electrode and the material to be worked to data of a stopping time changing data table 21, is outputted to a work electric power supply control device 16 from the NC program practicing device 20, and the moving command by which the wire electrode traces a machining passage is outputted to a motor control circuit 17 from a retreat control device 19. While observing output of a work voltage evaluating device 18, the retreat control device 19 retreats the wire electrode 1 until contact is released. Thereby, the wire electrode and the material to be worked are separated relatively from each other, and discharge is generated again, and retreat operation is finished, and is transferred to restoring operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire-cut electric discharge machining apparatus for canceling a short circuit between a wire electrode and a work piece by retreat control.

[0002]

2. Description of the Related Art In a conventional wire-cut electric discharge machining apparatus, when the wire electrode and a workpiece are short-circuited during machining and machining cannot proceed, the wire electrode and the table are moved relative to each other. The short circuit state of the wire electrode and the work piece is released by so-called retreat control, in which the machining path is reversed and the short circuit is released, and then the original machining position is restored.

A conventional wire cut electric discharge machine will be described below with reference to FIGS. 7 and 8. FIG. 7 is a diagram showing the configuration of a conventional wire electric discharge machining apparatus, in which 1 is a wire electrode,
2 is a work piece, 3 is a work piece 2 on which the X axis and the Y axis 2 are placed.
A table that freely moves in a dimensional plane, 4 is a wire bobbin, 5a and 5b are upper and lower machining liquid nozzles that supply a machining liquid to a machining gap formed between the wire electrode 1 and the workpiece 2, and 6 is a wire electrode. 1 is a power supply for supplying power, 7 is a tension roller for applying a tension to the wire electrode 1, 8 is a processed wire electrode collection box, and 9 is the wire electrode 1 and the workpiece 2.
A machining power supply that supplies a machining voltage between them, 10 is an X-axis motor that moves the table 3 in the X-axis direction, and 11 is a Y-axis of the table 3.
A Y-axis motor driven in the axial direction, 12 a voltage detection device between the wire electrode 1 and the workpiece 2, 13 an X-axis motor 10,
This is an NC device that controls the drive of the Y-axis motor 11 and the processing power supply. A magnetic disk 42 stores an NC program for machining.

FIG. 8 is a diagram showing the detailed construction of the NC device 13, in which 14 is a CRT for displaying the state of the wire cut electrical discharge machining device, 15 is an operation switch panel for operating the NC device 13, and FIG. Reference numeral 16 is a processing power supply control device for controlling the processing power supply 9, 17 is a motor control device for controlling the X-axis motor 10 and the Y-axis motor 11, and 18 is a voltage obtained from the voltage detection device 12 to evaluate the discharge state. A machining voltage evaluation device for controlling 19; a backward control device 19 for retracting the machining path to release the short circuit and restarting machining when a short circuit occurs during machining; 20 is an NC program (such as a paper tape or magnetic disk) This is an NC program execution device that interprets a machining program.

Next, the operation will be described. NC device 1
A procedure for processing the workpiece 2 in the wire-cut electric discharge machining apparatus including the 3 will be described. Workpiece 2 on table 3
Machining start hole 43 that is fixed to the
The wire electrode 1 is passed through, the magnetic disk 42 or the like is set in the NC program execution device 20, and machining is started. The NC program execution device 20 interprets the NC program, outputs a signal for controlling the machining power source to the machining power source control device 16 according to the command, and outputs a table movement command to the motor control device 17. Processing proceeds.

Machining is performed by applying a machining voltage between the wire electrode 1 and the workpiece 2 and using the discharge energy generated at that time. Therefore, the distance between the wire electrode 1 and the workpiece 2 must be maintained at a distance such that an electric discharge is generated. When the wire electrode 1 and the workpiece 2 are short-circuited, no discharge occurs even if a machining voltage is applied, and the machining does not proceed. When a short circuit occurs in this way, the movement command from the NC program execution device 20 is temporarily interrupted, and the movement control command that reverses the machining path is output from the retreat control device 19 to the motor control device 17. Here, the reverse control device 19
Observes the output of the machining voltage device 18 and retracts the wire electrode until the contact is released. As a result, the wire electrode 1 and the workpiece 2 are relatively separated from each other, and an electric discharge is generated again. Next, the wire electrode 1 is returned to the position where the machining path is started to be traced backwards while observing the output of the machining voltage evaluation device 18 as in the case of the retreat operation, and the operation of the retreat control device 19 is completed. Next, the machining is restarted by the movement command from the NC program execution device 20 again.

[0007]

Since the conventional wire electric discharge machining apparatus is constructed as described above, the contact state can be released by the retreat control in the case of an excessive short circuit state. When the wire electrode and the workpiece are short-circuited, the wire electrode is returned to the position where it started tracing the machining path in reverse without changing the electrical conditions even if the retracting control is performed. Although the short-circuited state is released, since the state of the wire electrode and the work piece has not changed from the state before the retreat control was performed, the retreat control is completed and the movement command is executed immediately again. It will be short-circuited. Therefore, the conventional wire-cut electric discharge machining apparatus has a problem that the machining does not progress due to repeated hunting and short circuit control depending on the situation of occurrence of the short circuit.

Further, if such a hunting state is continued for a long time, the short-circuited state is temporarily released during the backward control, but since the short-circuited state continues, an abnormality of the element in the machining power source is caused. There is a risk of element destruction and even fire due to the rise in temperature.

The present invention has been made to solve such conventional problems, and in the backward control of the wire cut electric discharge machine, a wire cut electric discharge machine capable of preventing a hunting state in which short circuit and backward control are repeated. Aim to get. It is another object of the present invention to obtain a wire cut electric discharge machining apparatus capable of stopping machining when machining is not progressed by repeating short circuit and retreat control.

[0010]

The wire-cut electric discharge machining apparatus according to the first aspect of the present invention is provided with change control means for changing and controlling the electric machining conditions during the backward control.

Further, the wire cut electric discharge machining apparatus according to the second invention is provided with means for returning the electromachining condition changed by the change control means to the electromachining condition before the short circuit when the machining after returning is stable. It is a thing.

Further, the wire cut electric discharge machining apparatus according to the third invention is provided with machining stopping means for stopping the machining when the short circuit is not released even after the backward control is performed a predetermined number of times or more.

[0013]

The change control means according to the first aspect of the present invention changes the electromachining conditions such as the dwell time of the pulse voltage applied to the machining gap during the retreat control so that the electromachining conditions after the retreat control can be performed before the short circuit. Different from the electrical processing conditions of
A so-called hunting state in which a short circuit and a backward control are repeated is prevented.

The means according to the second aspect of the invention restores the machining speed to the original speed quickly by returning to the value before changing the electromachining conditions such as the down time after the machining return.

Further, the machining stopping means according to the third aspect of the invention stops machining when machining does not progress at the same machining position by repeating short circuit and retreat control during machining.

[0016]

【Example】

Example 1. Hereinafter, one embodiment of the first invention will be described with reference to FIGS.
It will be explained based on. The hardware except the NC device 13 of the wire-cut electric discharge machine according to this embodiment is the same as that of the conventional example shown in FIG. FIG. 1 is a diagram showing a detailed configuration of the NC device 13. Reference numeral 14 is a CRT for displaying a state of the wire cut electric discharge machining device, 15 is an operation switch panel for operating the NC device 13, and 16 is a machining power source 9. A machining power source control device, 17 is a motor control device that controls the X-axis motor 10 and the Y-axis motor 11, 18 is a machining voltage evaluation device that evaluates the voltage obtained from the voltage detection device 12, and determines the discharge state, and 19 If a short circuit occurs during machining, the retract control device retracts the machining path, cancels the short circuit, and resumes machining.
20 is N given by paper tape, magnetic disk, etc.
NC program execution device for executing C program, 21
Is a table for storing data for changing the pause time.

Next, the operation will be described with reference to the flowchart shown in FIG. The operator places the workpiece 2 on the table 3, sets the NC program, and then starts machining (step 24). If the short-circuited state does not occur during machining, machining is performed according to the locus of the NC program, and the machining ends after step 25.

Next, when the wire electrode 1 and the workpiece 2 are short-circuited after the start of machining, the machining voltage evaluation device 18 determines in step 26 that there is a short circuit (contact), and a movement command from the NC program execution device 20 is issued. Is temporarily stopped, and the pause time of the pulsed voltage supplied between the wire electrode 1 and the workpiece 2 is changed from the NC program execution device 20 to the machining power supply controller 16 to the data of the pause time change data table 21. Is output (step 27), and the backward control device 19 outputs a movement command for the wire electrode 1 to follow the machining path in reverse to the motor control circuit 17. Then, the reverse control device 19 observes the output of the machining voltage evaluation device 18,
The wire electrode 1 is retracted until the contact is released (steps 28 and 29). As a result, the wire electrode 1 and the workpiece 2 are relatively separated from each other, and an electric discharge is generated again.
After the backward movement operation of 29, the operation returns to the returning operation of step 30.

The return operation in step 30 is performed while observing the output of the machining voltage evaluation device 18 as in the retreat operation, and when it is determined in step 31 that the wire electrode 1 has returned to the position where the retreat control was started, The returning operation ends, and the process moves to step 32 to restart the machining. When a short circuit occurs during machining in this way, by changing the pause time of the pulsed voltage and performing the backward control, machining is performed according to the trajectory of the NC program while smoothly avoiding the short circuit.

Example 2. Next, an embodiment of the second invention is shown in FIG.
And FIG. 4 will be described. The hardware except the NC device 13 of the wire-cut electric discharge machine according to this embodiment is the same as that of the conventional example shown in FIG. FIG. 3 is a diagram showing a detailed configuration of the NC device 13. Reference numeral 14 is a CRT for displaying the state of the wire cut electric discharge machining device, 15 is an operation switch board for operating the NC device 13, and 16 is a machining power source 9. A machining power source control device, 17 is a motor control device that controls the X-axis motor 10 and the Y-axis motor 11, 18 is a machining voltage evaluation device that evaluates the voltage obtained from the voltage detection device 12, and determines the discharge state, and 19 When a short circuit occurs during machining, a retraction control device that retreats the machining path to cancel the short circuit and restart machining again while changing the pause time of the pulsed machining voltage.
Is an NC program execution device for executing an NC program given by a paper tape, a magnetic disk, etc., 21 is a rest time change data storage table, and 22 is a rest time storage table.

Next, the operation will be described with reference to the flowchart shown in FIG. The operator places the workpiece 2 on the table 3, sets the NC program, and then starts machining (step 24). If the short-circuited state does not occur during machining, machining is performed according to the locus of the NC program, and the machining ends after step 25.

Next, when the wire electrode 1 and the workpiece 2 are short-circuited after the start of machining, the machining voltage evaluation device 18 determines in step 26 that there is a short circuit (contact), and a movement command from the NC program execution device 20 is issued. Is temporarily suspended, the current rest time is stored in the data table 22 (step 36), and then supplied from the NC program execution device 20 to the machining power supply controller 16 between the wire electrode 1 and the workpiece 2. A command to change the pause time of the pulsed voltage to the data in the pause time change data table 21 (the pause time is longer than the pause time before the short circuit) is output (step 2).
7), the backward control device 16 outputs a movement command for the wire electrode 1 to follow the machining path in the reverse direction to the motor control circuit 17.
Then, the retreat control device 19 observes the output of the machining voltage evaluation device 18 until the contact is released.
Are retracted (steps 28 and 29). As a result, the wire electrode 1 and the workpiece 2 are relatively separated from each other, electric discharge is generated again, the retreating operation of steps 28 and 29 is completed, and the returning operation of step 30 is performed. The return operation in step 30 is performed while observing the output of the machining voltage evaluation device 18 as in the retreat operation, and when it is determined in step 31 that the wire electrode 1 has returned to the position where the retreat control is started, the return operation is performed. When finished, the process moves to step 32 and the machining is restarted.

In step 25, it is determined that the process is not finished, and in step 33, the rest time storage table 22 is stored.
And the machining voltage evaluation device 18 stores the rest time in
When it is determined that the machining is stable by observing the data, the data in the data table 22 is changed to the NC program execution device 2
Data table 2 is returned to 0 (step 34).
The data of No. 2 is cleared (step 35), and the rest condition is restored. If a short circuit occurs during processing like this,
By changing the pause time of the pulsed voltage and performing the backward control, the short-circuit state can be avoided smoothly, and if it is determined that the machining is stable, the rest condition is returned to the original state and machining is performed according to the trajectory of the NC program. I do.

Example 3. Next, an embodiment of the third invention is shown in FIG.
And FIG. 6 will be described. The hardware except the NC device 13 of the wire-cut electric discharge machine according to this embodiment is the same as that of the conventional example shown in FIG. FIG. 5 is a diagram showing a detailed configuration of the NC device 13. Reference numeral 14 is a CRT for displaying the state of the wire cut electric discharge machining device, 15 is an operation switch panel for operating the NC device 13, and 16 is a machining power source 9. A machining power source control device, 17 is a motor control device that controls the X-axis motor 10 and the Y-axis motor 11, 18 is a machining voltage evaluation device that evaluates the voltage obtained from the voltage detection device 12, and determines the discharge state, and 19 When a short circuit occurs during machining, a retraction control device that retreats the machining path to cancel the short circuit and restart machining again while changing the pause time of the pulsed machining voltage.
Is an NC program execution device that executes an NC program given by a paper tape, a magnetic disk, or the like, 23 is a counter that counts the number of times the reverse control is performed, and 24 is the time during which the reverse control is repeatedly performed after the reverse control is started. It is a timer for measuring.

Next, the operation will be described with reference to the flowchart shown in FIG. The operator installs the work piece 2,
After setting the NC program, machining is started (step 24). Here, when the wire electrode 1 and the workpiece 2 are short-circuited after the start of machining, the backward control is performed to avoid the short-circuited state as in the conventional wire-cut electric discharge machining device. If the short circuit cannot be avoided even if the backward control is repeated, the following control is performed.

That is, during processing, the wire electrode 1 and the workpiece 2 are
If the machining gap is short-circuited, the machining voltage evaluation device 18 determines in step 26 that there is a short-circuit (contact), and the timer 37 starts in step 37. The movement command from the NC program execution device 20 is temporarily interrupted, and the movement control device 19 outputs a movement command for the wire electrode 1 to follow the machining path in the reverse direction to the motor control circuit 16 to perform the backward control and temporarily short-circuit. The condition is avoided (step 2)
8). Here, the number of times the reverse control is repeated in step 38 is counted by the counter 23. Then, in step 41, the number of times of the counter 23 becomes 4
If the set number of times is less than 1, the reverse control is repeatedly performed, but when the number of times of the counter 23 becomes equal to or more than the set number of times set by the timer 24 in step 41, it is determined that the processing is stopped and the processing is stopped. Processing is stopped to protect the elements of the power supply 9. Regarding the number of times of the counter 23 and the measurement time of the timer 24, after the return control is completed, the program execution device 20 outputs a command to reset the counter 23 and the timer 24 (steps 39 and 40).

Example 4. In the first and second embodiments, the pause time control is performed from the time of retreat. However, the intended purpose can be achieved by performing the pause time control only when returning. Further, in the above-described first and second embodiments, the case where the pause time control is performed has been described. However, the short circuit state can be avoided by changing the electromachining conditions other than the pause time of the pulsed voltage and performing the backward control. If so, it is not limited to the rest time. Furthermore, the first and second embodiments and the third embodiment may be combined.

[0028]

As described above, according to the first aspect of the invention, since the electromachining conditions such as the dwell time of the pulse voltage applied to the machining gap during the retreat control are changed, the electric power after the retreat control is controlled. Since the machining conditions are different from the electromachining conditions before the short circuit, it is possible to restart the machining even when the hunting state occurs and the machining does not progress conventionally.

According to the second aspect of the invention, when the machining is stable after the machining is resumed, the value before the electromachining conditions such as the down time is changed is returned to the value before the machining. You will be able to return to speed.

Furthermore, according to the third aspect of the invention, when the machining is not progressed by repeating the short circuit and the retreat control, the machining is stopped, so that the machining power source is prevented from being broken and the wire cut electric discharge machine is operated. This has the effect of greatly improving the rate and safety.

[Brief description of drawings]

FIG. 1 is a detailed configuration diagram showing an NC device of a wire cut electric discharge machine according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing an operation according to the first embodiment of the present invention.

FIG. 3 is a detailed configuration diagram showing an NC device of a wire cut electric discharge machine according to a second embodiment of the present invention.

FIG. 4 is a flowchart showing an operation according to the second embodiment of the present invention.

FIG. 5 is a detailed configuration diagram showing an NC device of a wire cut electric discharge machine according to a third embodiment of the present invention.

FIG. 6 is a flowchart showing an operation according to the third embodiment of the present invention.

FIG. 7 is a configuration diagram showing a conventional wire cut electric discharge machine.

FIG. 8 is a detailed configuration diagram showing an NC device of a conventional wire cut electric discharge machine.

[Explanation of symbols]

 13 NC Device 16 Machining Power Supply Control Device 18 Machining Voltage Evaluation Device 19 Retraction Control Device 20 NC Program Execution Device 21 Pause Time Change Data Storage Table 22 Pause Time Storage Table 23 Counter 24 Timer

[Procedure amendment]

[Submission date] May 13, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 4

[Correction method] Change

[Correction content]

[Figure 4]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

Claims (3)

[Claims] 1. Machining is performed while applying a pulsed voltage to a machining gap formed between a wire electrode and a workpiece, and retreat control is performed when the wire electrode and the workpiece are short-circuited during machining. A wire cut electric discharge machine comprising a retreat control device, comprising a change control means for changing and controlling an electric machining condition at the time of retreat control by the retreat control device. 2. The wire-cut electric discharge machine according to claim 1, further comprising means for returning the electromachining condition changed by the change control means to the electromachining condition before the short circuit when the post-return machining is stable. Wire cut electric discharge machine equipped. 3. Machining is performed while applying a pulse voltage to a machining gap formed between the wire electrode and the workpiece, and retreat control is performed when the wire electrode and the workpiece are short-circuited during machining. In a wire cut electric discharge machine including a retreat control device, the wire cut electric discharge machine including a machining stopping means for stopping the machining when the short circuit is not released even after the retreat control by the retreat control device is performed a predetermined number of times or more. .