JP2005118971A - Wire electric discharge machine and method for determining work reference position of wire electric discharge machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform operation in a relatively short time with high accuracy without disconnecting even a relatively thin wire electrode when determining a work reference position. <P>SOLUTION: A CPU 30 stores a contact position in a memory 38 (in rough positional detection) when detecting these contact by a contact detecting circuit 26 by approaching and moving a work W to the wire electrode 10 in the first place when determining the work reference position. Next, the CPU stores a second-time contact position in the memory 38 as the work reference position by contacting the work W again with the wire electrode 10 after separating the work W once. At this time, the CPU controls so that tension of the wire electrode 10 when contacting the work W in the first place with the wire electrode 10, becomes smaller than tension when contacting in the second place, by controlling a brake unit 20 for adjusting the tension of the wire electrode 10, and delays a second-time approaching-moving speed of the work W more than the first time. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wire electric discharge machine having a function of determining a machining reference position of a wire electrode with respect to a workpiece and a machining reference position determination method for the wire electric discharge machine.

2. Description of the Related Art Conventionally, in a wire electric discharge machine, an end face protruding function is used to determine an end face of a workpiece to be processed as a processing reference position of a wire electrode. In this end face projection function, while the wire electrode stretched in the vertical direction is fed in a fixed feeding direction, one of the wire electrode and the workpiece, for example, the workpiece is moved, and the wire electrode and the end surface of the workpiece are in contact with each other. If detected, the position at that time is determined as the processing reference position. Patent Document 1 also proposes a method in which a wire electrode and an end surface of a workpiece are brought into contact with each other a plurality of times, and preferable data is selected and determined as a reference position.
JP 2003-062724 A

  By the way, when determining the processing reference position, it is necessary to suppress the vibration of the wire electrode (running in the lateral direction) in order to accurately perform the end face alignment. It is preferable to set a large value. However, when a thin fine wire having a diameter of 0.15 mm or less is used, for example, when the tension of the wire electrode is set to be relatively large, the moving speed of the workpiece toward the wire electrode is high. If the wire electrode goes too far, there is a problem that the wire electrode is rubbed at the edge of the workpiece and is easily broken.

  On the other hand, if the wire electrode tension is relatively small when performing the end surface alignment, the wire electrode will not easily break, but the accuracy of the end surface alignment (accuracy of the processing reference position) There is a problem that is easy to get worse. This is because the wire electrode may vibrate due to the movement of the workpiece with respect to the wire electrode, and if the tension of the wire electrode is small, the amplitude width of the wire electrode becomes large and the amplitude width becomes an error as it is. is there.

In addition, it is conceivable to slow down the moving speed of the workpiece in the approaching direction with respect to the wire electrode so as to bring them into contact with each other slowly. There is a problem.
The present invention has been made to solve the above-described problems, and it is difficult to disconnect even a relatively thin wire electrode when determining a processing reference position, and is performed with high accuracy and in a relatively short time. It is an object of the present invention to provide a wire electric discharge machine capable of performing the above and a method for determining a processing reference position of the wire electric discharge machine.

In order to achieve the above object, the wire electric discharge machine of the present invention includes:
Moving means for relatively moving the workpiece and the wire electrode for processing the workpiece in a direction in which the workpiece approaches and a direction in which the workpiece is separated;
Tension adjusting means for adjusting the tension of the wire electrode;
Contact detection means for detecting contact between the wire electrode and the workpiece;
Position storage means for storing a contact position at the time when contact is detected by the contact detection means;
Control means for controlling the moving means, tension adjusting means and position storage means,
The control unit moves the at least one of the workpiece and the wire electrode in the direction in which the workpiece and the wire electrode approach each other by the moving unit when determining the machining reference position when the workpiece is machined. After the detection, at least one of the workpiece and the wire electrode is moved in the direction in which the workpiece and the wire electrode are separated from each other by the moving means, and then at least one of the workpiece and the wire electrode is moved again in the direction in which they are approached by the moving means. The contact detecting means detects the contact again, and the position storage means stores the contact position where the contact is detected again as a processing reference position, while the tension of the wire electrode when the contact is detected again is previously stored. Control is made so that the tension is larger than the tension when contact is detected.

In order to achieve a similar object, a method for determining a machining reference position of a wire electric discharge machine of the present invention includes:
Moving means for relatively moving the workpiece and the wire electrode for processing the workpiece in a direction in which the workpiece approaches and a direction in which the workpiece is separated;
Tension adjusting means for adjusting the tension of the wire electrode;
Contact detection means for detecting contact between the wire electrode and the workpiece;
A position storage means for storing a contact position at the time when contact is detected by the contact detection means;
When determining the processing reference position when processing the workpiece, after moving at least one of the workpiece and the wire electrode in the direction in which they are approached by the moving means and detecting contact by the contact detecting means, At least one of the workpiece and the wire electrode is moved in a direction in which the workpiece and the wire electrode are separated from each other by the moving means, and thereafter, at least one of the workpiece and the wire electrode is moved again in the direction in which the workpiece and the wire electrode are approached. The contact is detected again by the means, and the contact position where the contact is detected again is stored in the position storage means as the machining reference position, while the tension of the wire electrode when the contact is detected again is detected before that time. It is characterized by being larger than the tension at the time.

  According to the wire electric discharge machine of the present invention, when the wire electrode and the workpiece are first contacted, it is only necessary to know a relatively rough position. In this case, the tension of the wire electrode is made relatively small. Therefore, even in the case of a relatively thin wire electrode, the wire electrode can be prevented from being disconnected as much as possible. At this time, the moving speed of the wire electrode and the workpiece in the approaching direction can be relatively high. When the wire electrode and the workpiece are brought into contact again, the contact position between the wire electrode and the workpiece can be accurately detected by setting the tension of the wire electrode to be relatively large. Determine as the reference position. Thus, when determining the processing reference position, it is difficult to disconnect even a relatively thin wire electrode, the accuracy is high, and the processing can be performed in a relatively short time.

  Moreover, according to the processing reference position determination method of the wire electric discharge machine of the present invention, the same operational effects as those of the above-described wire electric discharge machine can be obtained.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a portion related to the gist of the present invention in a wire electric discharge machine. In FIG. 1, a table 1 is configured to be movable in the Y direction by a Y axis moving mechanism 3 having a Y axis motor 2. A work mount 4 provided on the table 1 is configured to be movable in the X direction by an X-axis moving mechanism 6 having an X-axis motor 5. A workpiece W to be processed is detachably attached to the workpiece mounting base 4, and the workpiece W attached to the workpiece mounting base 4 is X, Y by the X-axis moving mechanism 6 and the Y-axis moving mechanism 3. It can move in the direction. The Y-axis moving mechanism 3 and the X-axis moving mechanism 6 constitute the moving means of the present invention.

  The wire electrode 10 for processing the workpiece W is routed as shown in FIG. The wire electrode 10 wound around the wire bobbin 11 includes a guide roller 14, an upper wire guide 15, a lower wire guide 16, a guide roller 17, a collection roller 18 and a pinch roller 19 between the brake roller 12 and the pinch roller 13. Have been passed. Among these, the collection | recovery roller 18 rotates in the arrow A1 direction, and the wire electrode 10 is sent to the arrow A2 direction. The wire electrode 10 is guided in the vertical direction by an upper wire guide 15 and a lower wire guide 16. The brake roller 12 is provided with a brake unit 20, and the tension of the wire electrode 10 can be adjusted based on controlling the rotation of the brake roller 12 by the brake unit 20.

  The brake unit 20 is configured by, for example, a powder brake, and the tension is changed by changing the value of a current that flows from the tension controller 36 to the powder brake. The brake unit 20 constitutes a tension adjusting means of the present invention. The brake unit 20 may use a motor instead of the powder brake, or may use a disc brake or a hydraulic brake. A collection container 21 for collecting the used wire electrode 10 is installed below the collection roller 18. In addition, the thickness (diameter) of the wire electrode 10 is, for example, 0.15 mm.

  Above the upper wire guide 15, an electron supply 25 is disposed so as to contact the wire electrode 10. The power supply 25 and the work mounting base 4 are connected to a contact detection circuit 26. The contact detection circuit 26 detects a contact between the wire electrode 10 and the workpiece W and outputs a detection signal to the CPU 30 constituting the control means. This contact detection circuit 26 constitutes the contact detection means of the present invention.

  The CPU 30 controls the entire machining operation of the wire electric discharge machine. Based on a control program, the CPU 30 moves the collection roller 18 via the collection roller controller 31 and the X axis via the X controller 32 and the X driver 33. The motor 5 has a function of controlling the Y-axis motor 3 via the Y controller 34 and the Y driver 35, the brake unit 20 via the tension controller 36, and the display 37. The CPU 30 is connected to a memory 38 constituting the position storage means of the present invention. The wire electric discharge machine is also provided with a circuit for applying a voltage for electric discharge machining to the wire electrode 10, but illustration and description thereof are omitted.

  Next, the end face projection processing of the CPU 30 when determining the processing reference position when processing the workpiece W will be described with reference to FIGS. This end face setting process is performed based on an operation of an end face setting key (not shown). There are two types of end surface key, one for the X-axis direction and the other for the Y-axis direction. In the following, a case where the end surface key for the X-axis direction is operated will be described. Further, in the case where the Y-axis direction end key is operated, in the following description, “X-axis direction” is read as “Y-axis direction”, and “X-axis motor 5” is replaced with “Y-axis motor 3”. And shall be read as

  First, the CPU 30 starts feeding the wire electrode 10 by driving the collection roller 18 and sets the tension of the wire electrode 10 to “small” by controlling the brake unit 20 (step S1). At this time, the collection roller 18 is rotated in the arrow A1 direction, and the wire electrode 10 is sent in the arrow A2 direction. The tension of the wire electrode 10 is set according to the diameter (wire diameter) and type of the wire electrode. FIG. 4 shows an example of the relationship between the wire diameter and the tension. The tension of the wire electrode in step 1 is the previous tension (first tension) in FIG. When the wire diameter is 0.15 mm, the tension of the wire electrode in Step 1 is 7 Newton. Types of wire electrodes include brass, tungsten, brass + zinc and the like. The type and diameter of the wire electrode may be input by a user in advance from a keyboard or set by a machining program.

Next, the CPU 30 drives the X-axis motor 5 to start the approaching movement of the workpiece W with respect to the wire electrode 10 (step S2). The moving speed at this time is set to “large”. Thereby, the workpiece | work W attached to the workpiece | work mounting base 4 moves to the direction which approaches the wire electrode 10 (refer Fig.3 (a)).
When the workpiece W comes into contact with the wire electrode 10, the contact detection circuit 26 detects this and outputs a detection signal to the CPU 30. When the detection signal from the contact detection circuit 26 is input (“YES” in step S3), the CPU 30 stops driving the X-axis motor 5 to stop the approaching movement of the workpiece W (step S4). The position (first contact position) is stored in the memory 38 (step S5).

  At this time, since the moving speed of the workpiece W is set to “high”, the workpiece W is fast, and the workpiece W slightly overruns the contact position with the wire electrode 10 (see FIG. 3B). The contact position (first contact position) is a rough position. At this time, although the wire electrode 10 may be rubbed by the edge We of the workpiece W, since the tension of the wire electrode 10 is set to be small, it is possible to prevent the wire electrode 10 from being disconnected as much as possible.

  Next, the CPU 30 drives the X-axis motor 5 to move the workpiece W in a direction away from the wire electrode 10 by a predetermined distance (step S6, see FIG. 3C). Then, the tension of the wire electrode 10 is set to “large” so as to be stronger than the first time by controlling the brake unit 20 (step S7) The tension at this time is the tension at the time of determining the reference position in FIG. In this case, the tension is 12 Newtons, and the X-axis motor 5 is driven to start the approaching movement of the workpiece W with respect to the wire electrode 10 (step S8). The speed is set to “small” so as to be slower than the first time, whereby the work W attached to the work mounting base 4 moves in a direction approaching the wire electrode 10 (see FIG. 3D).

  When the workpiece W comes into contact with the wire electrode 10 (see FIG. 3E), the contact detection circuit 26 detects this and outputs a detection signal to the CPU 30. When the detection signal from the contact detection circuit 26 is input (“YES” in step S9), the CPU 30 stops driving the X-axis motor 5 to stop the approaching movement of the work W and stops driving the collection roller 18. Thus, the feeding of the wire electrode 10 is stopped (step S10). Then, the contact position at this time (second contact position) is stored in the memory 37 as a processing reference position and displayed on the display 37 (step S11). In this process, the X coordinate of the workpiece mounting base 4 in the machine coordinate system when the workpiece W comes into contact with the wire electrode 10 is stored as the machining reference position. Thus, the end face drawing process is completed.

  In the above-described embodiment, when the processing reference position is determined, when the wire electrode 10 and the workpiece W are contacted for the first time, it is only necessary to know a relatively rough position. By keeping the tension of the electrode 10 relatively small, even when the wire electrode 10 is relatively thin, disconnection of the wire electrode 10 can be prevented as much as possible. At this time, the moving speed of the wire electrode 10 and the workpiece W in the approaching direction can be relatively high. When the wire electrode 10 and the workpiece W are contacted for the second time, the contact position between the wire electrode 10 and the workpiece W can be accurately detected by setting the tension of the wire electrode 10 to be relatively large. This is determined as the processing reference position. In this way, when determining the processing reference position, even a relatively thin wire electrode W is difficult to be disconnected, and it is possible to carry out with high accuracy and in a relatively short time.

  Further, when the wire electrode 10 and the workpiece W are brought into contact for the second time, the workpiece W can be stopped at a position as close as possible to the contact position by slowing the moving speed of the workpiece W. The position accuracy is further increased. Furthermore, by setting the tension of the wire electrode 10 according to the diameter and type of the wire electrode 10, the processing reference position can be determined more satisfactorily.

The present invention is not limited to the above-described embodiment, and can be modified or expanded as follows.
In the above-described embodiment, when the processing reference position is determined, the workpiece W and the wire electrode 10 are brought into contact with each other twice. In the present invention, at least the tension when detecting contact as the processing reference position (the tension when detecting contact again) may be set to be larger than the tension when contacting before.

In the above-described embodiment, the workpiece W is moved with respect to the wire electrode 10, but the wire electrode 10 side can be moved in the X and Y directions while the workpiece W is fixed.
In the above-described embodiment, the workpiece W is moved in the horizontal direction with respect to the wire electrode 10 in a state where the wire electrode 10 is directed in the vertical direction. However, the wire electrode 10 is oriented in the horizontal direction. In this state, at least one of the wire electrode 10 and the workpiece W can be moved in the vertical direction.

The schematic block diagram of the wire electric discharge machine which shows one Embodiment of this invention. CPU end face drawing process flowchart (A)-(e) is operation | movement explanatory drawing for demonstrating end surface projection operation | movement. Diagram showing the relationship between wire electrode diameter (wire diameter) and tension

Explanation of symbols

In the drawings, 1 is a table, 3 is a Y-axis moving mechanism (moving means), 4 is a work mounting base, 6 is a Y-axis moving mechanism (moving means), 10 is a wire electrode, 12 is a brake roller, and 15 is an upper wire guide. , 16 is a lower wire guide, 18 is a recovery roller, 20 is a brake unit (tension adjusting means), 25 is a power supply, 26 is a contact detection circuit (contact detection means), 30 is a CPU (control means), and 38 is a memory ( Position storage means), W is a workpiece.

Claims (6)

Moving means for relatively moving the workpiece and the wire electrode for processing the workpiece in a direction in which the workpiece approaches and a direction in which the workpiece is separated;
Tension adjusting means for adjusting the tension of the wire electrode;
Contact detection means for detecting contact between the wire electrode and the workpiece;
Position storage means for storing a contact position at the time when contact is detected by the contact detection means;
Control means for controlling the moving means, tension adjusting means and position storage means,
The control unit moves the at least one of the workpiece and the wire electrode in the direction in which the workpiece and the wire electrode approach each other by the moving unit when determining the machining reference position when the workpiece is machined. After the detection, at least one of the workpiece and the wire electrode is moved in the direction in which the workpiece and the wire electrode are separated from each other by the moving means, and then at least one of the workpiece and the wire electrode is moved again in the direction in which they are approached by the moving means. The contact detecting means detects the contact again, and the position storage means stores the contact position where the contact is detected again as a processing reference position, while the tension of the wire electrode when the contact is detected again is previously stored. A wire electric discharge machine that controls to be larger than the tension when contact is detected.   The control means moves at least one of the workpiece and the wire electrode in the direction in which they are once separated by the moving means, and then sets the moving speed when moving again in the approaching direction than the moving speed in the previous approaching direction. The wire electric discharge machine according to claim 1, wherein the moving means is controlled so as to be slow.   The wire electric discharge machine according to claim 1 or 2, wherein the wire electrode is moved in the feed direction when the machining reference position is determined.   The wire electric discharge machine according to any one of claims 1 to 3, wherein the tension of the wire electrode is set according to the diameter and type of the wire electrode. Moving means for relatively moving the workpiece and the wire electrode for processing the workpiece in a direction in which the workpiece approaches and a direction in which the workpiece is separated;
Tension adjusting means for adjusting the tension of the wire electrode;
Contact detection means for detecting contact between the wire electrode and the workpiece;
A position storage means for storing a contact position at the time when contact is detected by the contact detection means;
When determining the processing reference position when processing the workpiece, after moving at least one of the workpiece and the wire electrode in the direction in which they are approached by the moving means and detecting contact by the contact detecting means, At least one of the workpiece and the wire electrode is moved in a direction in which the workpiece and the wire electrode are separated from each other by the moving means, and thereafter, at least one of the workpiece and the wire electrode is moved again in the direction in which the workpiece and the wire electrode are approached. The contact is detected again by the means, and the contact position where the contact is detected again is stored in the position storage means as the machining reference position, while the tension of the wire electrode when the contact is detected again is detected before that time. A method for determining a machining reference position of a wire electric discharge machine, wherein the tension is larger than the tension at the time.   After moving at least one of the workpiece and the wire electrode in the direction in which they are once separated by the moving means, the moving speed when moving in the approaching direction again is slower than the moving speed in the approaching direction before that. 6. A method for determining a machining reference position of a wire electric discharge machine according to claim 5, wherein the machining reference position is determined.

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