Wire electrical discharge machine and disconnection state determination method

Abstract

To provide a wire electrical discharge machine or the like suitable for detecting a disconnection state of a wire using a detection pulley between a bobbin and a roller.SOLUTION: A wire electrical discharge machine 1 for machining using a wire includes a bobbin 5, a detection pulley 9, a supply roller 13, an injector 17, and a control unit 19. The wire drawn from the bobbin 5 reaches the supply roller 13 via the detection pulley 9. The detection pulley 9 includes a rotation state detection device. The rotation state detection device detects the rotation state of the detection pulley 9 and outputs detection data. The injector 17 sprays fluid to a part or all of the portion that is in contact with the wire on the surface of the supply roller 13. After the injector 17 sprays the fluid onto the surface of the supply roller 13, the control unit 19 uses the detection data to determine that the wire is in a disconnection state if the detection pulley 9 does not rotate in a state where the supply roller 13 is rotating.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wire electrical discharge machining machine and a method for determining a wire break state, and more particularly to a wire electrical discharge machining machine that performs machining using a wire.

Background Art

[0002] As disclosed in Patent Document 1 and the like, the applicant has proposed not to provide a roller between the supply roller and the upper head.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, wire breakage often occurs due to machining. Therefore, a process for detecting wire breakage is required without providing a roller between the supply roller and the upper head.

[0005] Therefore, an object of the present invention is to provide a wire electrical discharge machining machine and the like suitable for detecting a wire break state using a detection pulley between a bobbin and a roller.

Means for Solving the Problems

[0006] A first aspect of the present invention is a wire electrical discharge machining apparatus that performs machining using a wire, comprising a bobbin, a detection pulley, a roller, an injector, and a control unit. The wire drawn from the bobbin reaches the roller via the detection pulley. The detection pulley is provided with a rotation state detection device that detects the rotation state of the detection pulley and outputs detection data. The injector injects fluid onto part or all of the portion of the surface of the roller that contacts the wire. After the injector injects fluid onto the surface of the roller, the control unit uses the detection data to determine that the wire is broken if the detection pulley is not rotating while the roller is rotating.

[0007] A second aspect of the present invention is the wire electrical discharge machining apparatus according to the first aspect, wherein the roller is a supply roller located above the upper head.

[0008] A third aspect of the present invention is the wire electrical discharge machining apparatus according to the first or second aspect, wherein the injector injects fluid onto the surface of the roller before or simultaneously with the roller reversing. After the injector injects fluid, the control unit uses the detection data to determine that the wire is broken if the detection pulley is not rotating while the roller is rotating forward.

[0009] A fourth aspect of the present invention is the wire electrical discharge machining apparatus according to any one of the first to third aspects, wherein at least a part of the position on the surface of the roller where the injector injects fluid has a different distance from the central axis than other portions, and / or a different distance from the central axis than the distance in the machining process, and / or a different material.

[0010] The fifth aspect of the present invention is a method for determining a wire break state in a wire electrical discharge machining machine that performs machining using a wire. The wire electrical discharge machining machine includes a bobbin, a detection pulley, a roller, an injector, and a control unit. The wire drawn from the bobbin reaches the roller via the detection pulley. The detection pulley is provided with a rotation state detection device. The rotation state detection device detects the rotation state of the detection pulley and outputs detection data. A step of the injector injecting fluid to a part or all of a portion where the wire contacts the surface of the roller; and a step of the control unit, after the injector injects fluid to the surface of the roller, using the detection data, if the detection pulley is not rotating while the roller is rotating, determining that the wire is broken.

[0011] The sixth aspect of the present invention is the method for determining a wire break state according to the fifth aspect, including a step of the roller rotating in reverse. The injector injects fluid to the surface of the roller before or simultaneously with the roller rotating in reverse. The control unit, after the injector injects fluid, uses the detection data to determine that the wire is broken if the detection pulley is not rotating while the roller is rotating forward.

Advantages of the Invention

[0012] According to each aspect of the present invention, by using an injector to remove the wire fixed to the surface of the roller, the wire break state can be detected using the detection pulley between the bobbin and the roller.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Best Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments of the present invention are not limited to the following examples.

Example

[0015] FIG. 1 shows an example of the configuration of a wire electrical discharge machining machine according to an embodiment of the present invention.

[0016] The wire electrical discharge machining machine 1 includes a control unit 19, a supply unit 3, an upper head 21, a lower head 23, a lower head roller 25, a pressing roller 27, a take-up roller 29, and a waste wire hopper 31.

[0017] The control unit 19 can be realized by using an information processing device such as a processor that operates under the control of a program, and performs processing for controlling the wire electrical discharge machining machine 1.

[0018] The supply unit 3 includes a bobbin 5, a macla roller 7, a detection pulley 9, a pulley 11, a supply roller 13, a supply auxiliary roller 15, an injector 17, and a detector 18.

[0019] The bobbin 5 holds the supplied wire in a wound state. The wire drawn from the bobbin 5 is supplied downward through the macla roller 7, the detection pulley 9, the pulley 11, and the supply roller 13.

[0020] The detection pulley 9 is a pulley equipped with a rotation state detection device. The rotation state detection device detects the rotation state of the detection pulley 9 and outputs detection data. The rotation state detection device is, for example, an encoder. The rotation state detection device performs different processes depending on whether the detection pulley 9 is rotating or not. For example, when the rotation state detection device outputs detection data indicating the rotation speed of the detection pulley 9, the rotation state detection device increases the rotation speed when the detection pulley 9 is rotating, and does not increase the rotation speed when the detection pulley 9 is not rotating. Therefore, the control unit 19 can determine whether the detection pulley 9 is rotating based on the detection data output by the rotation state detection device.

[0021] The detection pulley 9 is located between the bobbin 5 and the supply roller 13. That is, the wire drawn from the bobbin 5 reaches the supply roller 13 via the detection pulley 9. The supply roller 13 is located above the upper head 21 and changes the direction of the wire drawn from the bobbin 5. The detection pulley 9 is not on the straight line connecting the supply roller 13 and the upper head 21.

[0022] The supply auxiliary roller 15 is pressed against the surface of the supply roller 13 when the connection operation is performed.

[0023] The injector 17 is a device that injects fluid into part or all of the portion (hereinafter referred to as the "wire contact portion") that contacts the wire on the surface of the supply roller 13. The fluid is a gas (such as air), a liquid, or the like.

[0024] The detector 18 is for detecting the end of the wire. The detector 18 is located upstream (on the side of the bobbin 5) from the upper head 21.

[0025] The wire supplied downward from the supply unit 3 passes through the upper head 21 and the lower head 23 in sequence, is laterally redirected by the lower head roller 25, is sandwiched between the pressing roller 27 and the winding roller 29, and is discharged to the discharge wire hopper 31. The processing unit 20 is a place where processing is performed and includes the space between the upper head 21 and the lower head 23.

[0026] For the "forward rotation" and "reverse rotation" of each roller (such as bobbin 5, supply roller 13, winding roller 29, etc.), use them as follows. "Forward rotation" is the direction of rotation for moving the wire to be drawn out from bobbin 5 and discharged to the discharge wire hopper 31. "Reverse rotation" is the direction of rotation opposite to the forward rotation. For example, in FIG. 1, the "forward rotation" of bobbin 5 is clockwise, and the "reverse rotation" is counterclockwise. The "forward rotation" of supply roller 13 is counterclockwise, and the "reverse rotation" is clockwise. The "forward rotation" of winding roller 29 is counterclockwise, and the "reverse rotation" is clockwise.

[0027] FIG. 2 is a diagram showing an example where the wire is cut at position 41 between the upper head 21 and the lower head 23. The present invention is for determining whether the wire is in a disconnected state where the wire is cut.

[0028] The connected wire is drawn out from bobbin 5 by the forward rotation of supply roller 13 and winding roller 29, passes through supply roller 13, is wound by winding roller 29, and is discharged to discharge wire hopper 31. At this time, a tension adjusted for processing is applied to the wire between the upper head 21 and the lower head 23. Since there is no other roller between supply roller 13 and lower head roller 25 in wire electrical discharge machine 1, the tension can be appropriately adjusted between supply roller 13 and lower head roller 25. And there is also tension between bobbin 5 and supply roller 13. The wire is in contact with the surface of detection pulley 9 between bobbin 5 and supply roller 13. Detection pulley 9 rotates as the wire moves. Therefore, when control unit 19 determines that detection pulley 9 is also rotating based on detection data when at least one of the other rollers (such as bobbin 5, supply roller 13, winding roller 29, etc.) rotates, it can be determined that the wire is not in a disconnected state (but in a connected state).

[0029] If the wire breaks, the tension of the wire is lost, and the wire floats from the surface of the detection pulley 9 (a state where it does not contact the surface). Then, even if the supply roller 13, the take-up roller 29, etc. rotate, the detection pulley 9 does not rotate. Therefore, when at least one of the other rollers (for example, the bobbin 5, the supply roller 13, the take-up roller 29, etc.) rotates and the control unit 19 determines based on the detection data that the detection pulley 9 is in a non-rotating state (rotation stopped), it can be determined that there is a possibility that the wire is in a broken state (there is a suspicion of wire breakage).

[0030] Note that the detection pulley 9 does not rotate if the wire between the bobbin 5 and the supply roller 13 does not move. Therefore, even if the control unit 19 determines based on the detection data that the detection pulley 9 is in a non-rotating state when all the other rollers are not rotating, it does not determine that there is a possibility that the wire is in a broken state.

[0031] Figure 3 is a flowchart showing an example of the process when the control unit 19 determines that there is a possibility that the wire is in a broken state.

[0032] The control unit 19 stops the supply roller 13 and the take-up roller 29 (step STA1). Here, the supply auxiliary roller 15 is in a released state and is not pressed against the surface of the supply roller 13.

[0033] The control unit 19 starts the reverse rotation (wire take-up) of the bobbin 5 (step STA2). The position 41 in Figure 2 moves upward. The detector 18 detects the end of the wire (step STA3). The control unit 19 stops the reverse rotation of the bobbin 5 (step STA4). Note that when the detector 18 detects the end of the wire, the control unit 19 may proceed to step STA9, determine that it is a break, and perform the connection work (step STA10).

[0034] The control unit 19 reverses the supply roller 13 (step STA5). The reverse rotation is, for example, about 90°.

[0035] Ideally, in the case of a wire break, the tension in the wire disappears, and the wire becomes slack (the state where it was taut becomes loose) between the bobbin 5 and the supply roller 13. Furthermore, by the process in step STA5, the tension in the wire between the bobbin 5 and the supply roller 13 is removed, and the wire surely becomes slack. When the wire becomes slack, the wire floats from the surface of the detection pulley 9 etc. (the state of not contacting the surface), and even if the supply roller 13 rotates forward, the detection pulley 9 does not rotate.

[0036] However, in reality, the wire may be fixed to the surface of the supply roller 13 due to the wire biting into the surface of the supply roller 13 etc. Then, even though the wire is broken, when the supply roller 13 rotates forward, the slack in the wire is eliminated and the wire comes into contact with the surface of the detection pulley 9 and the detection pulley 9 rotates, and there may be a case where the control unit 19 erroneously determines that it is in the connected state based on the detection data.

[0037] In step STA5, simultaneously with the reverse rotation, the injector 17 injects a fluid such as air into a part or all of the wire contact portion (the portion that contacts the wire on the surface of the supply roller 13). By the injector 17 injecting the fluid, the wire fixed to the surface of the supply roller 13 can be removed. That is, in addition to the process of advancing or retracting the wire in its traveling direction, the injector 17 applies an external force to the wire fixed to the surface of the supply roller 13 to remove it. As a result, the wire comes off the supply roller 13 and becomes slack, and floats from the surface of the detection pulley 9. In step STA5, the injector 17 may inject before reversing the supply roller 13. At this time, while the supply roller 13 is rotating in reverse, the injector 17 may or may not inject the fluid.

[0038] The control unit 19 rotates the supply roller 13 and the take-up roller 29 forward (step STA6). The control unit 19 uses the detection data to determine whether or not the detection pulley 9 is also rotating in the state where the supply roller 13 and the take-up roller 29 are rotating (step STA7).

[0039] In the determination of step STA7, if it is determined that the state is a rotating state, it is determined that the wire is not in a disconnected state (in a connected state) (step STA8), and the process proceeds to the next step. For example, if there is a machining instruction, machining is started.

[0040] In the determination of step STA7, if it is determined that the state is a non-rotating state, it is determined that the wire is in a disconnected state (step STA9), connection work is performed (step STA10), and the process proceeds to the next step. For example, if there is a machining instruction, machining is started.

[0041] In addition, in this embodiment, although the injector 17 has been described as an example of injecting onto the surface of the supply roller 13, it may be located between the bobbin 5 and the supply roller 13 and inject fluid onto the surface of a roller different from the detection pulley 9 (for example, the pulley 11).

[0042] Further, the surface of the roller (such as the supply roller 13) may be suitable for removing the fixed wire at least in part of the position where the injector 17 injects the fluid. For example, at least part of the position where the injector 17 injects the fluid on the surface of the roller may have a different distance from the central axis than other parts. This difference in distance may exist continuously, or may occur temporarily at the timing when the injector 17 injects. Also, at least part of the position where the injector 17 injects the fluid on the surface of the roller may have a different distance from the central axis in the machining process and the distance when the injector 17 injects. Further, at least part of the position where the injector 17 injects the fluid on the surface of the roller may have a different material from other parts.

Explanation of Signs

[0043] 1 Wire electrical discharge machining machine 3 Supply unit 5 Bobbin 7 Macro roller 9 Detection pulley 11 Pulley 13 Supply roller 15 Supply auxiliary roller 17 Injector 18 Detector 19 Control unit 20 Processing unit 21 Upper head 23 Lower head 25 Lower head roller 27 Pressing roller 29 Take-up roller 31 Waste wire hopper

Claims

1. A wire electrical discharge machining machine that performs machining using a wire, comprising: a bobbin, a detection pulley, a roller, an injector, and a control unit; the wire drawn from the bobbin reaches the roller via the detection pulley; the detection pulley is provided with a rotation state detection device; the rotation state detection device detects the rotation state of the detection pulley and outputs detection data; the injector injects fluid to a part or all of a portion in contact with the wire on the surface of the roller; after the injector injects fluid onto the surface of the roller, the control unit uses the detection data to determine that the wire is broken if the detection pulley is not rotating while the roller is rotating. A wire electrical discharge machining machine.

2. The wire electrical discharge machining machine according to claim 1, wherein the roller is a supply roller located above the upper head.

3. The injector injects fluid onto the surface of the roller before the roller reverses or simultaneously; after the injector injects fluid, the control unit uses the detection data to determine that the wire is broken if the detection pulley is not rotating while the roller is rotating forward. The wire electrical discharge machining machine according to claim 1.

4. In the wire electrical discharge machining machine according to claim 1, at least a part of the position where the injector injects fluid on the surface of the roller has a different distance from the central axis than other parts, and / or a different distance from the central axis than the distance in the machining process, and / or a different material.

5. A method for determining a wire break state in a wire electrical discharge machining machine that performs machining using a wire, the wire electrical discharge machining machine comprising a bobbin, a detection pulley, a roller, an injector, and a control unit; the wire drawn from the bobbin reaches the roller via the detection pulley; the detection pulley is provided with a rotation state detection device; the rotation state detection device detects the rotation state of the detection pulley and outputs detection data; a step of the injector injecting fluid to a part or all of a portion in contact with the wire on the surface of the roller; a method for determining a wire break state, including a step in which, after the injector injects fluid onto the surface of the roller, the control unit uses the detection data to determine that the wire is broken if the detection pulley is not rotating while the roller is rotating.

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