Control device and recording medium recording a program

Abstract

The present invention provides a control device and a recording medium having a program recorded thereon, which can improve the measurement accuracy of the relative position between a wire electrode and a workpiece by improving the detection accuracy of detecting the contact between the wire electrode and the workpiece. After performing a first detection operation for detecting the contact between the wire electrode and the workpiece at a first relative movement speed and a first pulse period, the contact detection unit performs a second detection operation for detecting the contact between the wire electrode and the workpiece at a second relative movement speed slower than the first relative movement speed and a second pulse period longer than the first pulse period. Before performing the second detection operation after performing the first detection operation, the movement speed control unit relatively moves the wire electrode and the workpiece in a direction away from each other.

Description

Technical Field

[0001] The present invention relates to a control device and a recording medium storing a program. Background Art

[0002] Conventionally, a wire electrical discharge machining machine is known which machines a workpiece by causing discharge to occur in an electrode gap between a wire electrode and the workpiece. In the wire electrical discharge machining machine, while discharge is occurring, the relative position between the wire electrode and the workpiece is changed by the operation of a servo motor. Thereby, the wire electrical discharge machining machine can machine the workpiece into a desired shape.

[0003] When machining a workpiece, positioning of the wire electrode and the workpiece is performed. As a device for performing such positioning of the wire electrode and the workpiece, for example, a contact detection device of a discharge machining machine that detects contact between the wire electrode and the workpiece to perform positioning has been proposed (for example, refer to Patent Document 1).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013 - 226612 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In Patent Document 1, a detection voltage is applied to the electrode gap between the wire electrode and the workpiece. Further, in Patent Document 1, contact is determined based on a change in the detection voltage generated by contact between the wire electrode and the workpiece. Thereby, the relative position (the end face of the workpiece) between the wire electrode and the workpiece is detected. Moreover, in Patent Document 1, machining of the workpiece is started using the detected position as a reference position.

[0009] Further, since the wire electrode vibrates slightly, when the wire electrode approaches the workpiece, discharge occurs in the electrode gap corresponding to the vibration. The wire electrode receives a repulsive force due to the discharge, and thus vibrates more greatly. Since the vibration increases, the number of discharges occurring in the electrode gap between the wire electrode and the workpiece increases. As a result, the number of discharge marks on the workpiece surface increases, and thus sometimes the detection accuracy deteriorates. Therefore, if the detection accuracy of detecting contact between the wire electrode and the workpiece can be improved, the accuracy of the relative position between the wire electrode and the workpiece can be improved, and thus it is preferable.

[0010] Solutions for Solving the Problems

[0011] (1) The present disclosure relates to a control device for controlling a wire electrical discharge machining machine having a moving drive unit that relatively moves a wire electrode and a workpiece. The control device measures the relative position between the wire electrode and the workpiece by detecting the contact between the relatively moving wire electrode and the workpiece. The control device includes: a period setting unit that sets a pulse period of a detection voltage applied between the poles between the wire electrode and the workpiece; a voltage application unit that applies the detection voltage between the poles at the set period; a relative movement speed control unit that controls the relative movement speed generated by the moving drive unit; and a contact detection unit that detects the contact between the wire electrode and the workpiece based on the change in the applied detection voltage. Among them, after performing a first detection operation for the contact between the wire electrode and the workpiece at the first relative movement speed and the first pulse period, the contact detection unit performs a second detection operation for the contact between the wire electrode and the workpiece at a second relative movement speed slower than the first relative movement speed and a second pulse period longer than the first pulse period. Before performing the second detection operation after performing the first detection operation, the relative movement speed control unit relatively moves the wire electrode and the workpiece in a separating direction.

[0012] (2) Further, the present disclosure relates to a computer-readable recording medium storing a program that causes a computer to function as a control device for controlling a wire electrical discharge machining machine having a moving drive unit that relatively moves a wire electrode and a workpiece. The control device measures the relative position between the wire electrode and the workpiece by detecting the contact between the relatively moving wire electrode and the workpiece. The program causes the computer to function as the following units: a period setting unit that sets a pulse period of a detection voltage applied between the poles between the wire electrode and the workpiece; a voltage application unit that applies the detection voltage between the poles at the set period; a relative movement speed control unit that controls the relative movement speed generated by the moving drive unit; and a contact detection unit that detects the contact between the wire electrode and the workpiece based on the change in the applied detection voltage. Among them, after performing a first detection operation for the contact between the wire electrode and the workpiece at the first relative movement speed and the first pulse period, the contact detection unit performs a second detection operation for the contact between the wire electrode and the workpiece at a second relative movement speed slower than the first relative movement speed and a second pulse period longer than the first pulse period. Before performing the second detection operation after performing the first detection operation, the relative movement speed control unit relatively moves the wire electrode and the workpiece in a separating direction.

[0013] Effects of the Invention

[0014] According to the present disclosure, it is possible to provide a control device and a recording medium having a program recorded thereon that can improve the measurement accuracy of the relative position between a wire electrode and a workpiece by improving the detection accuracy of detecting the contact between the wire electrode and the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a block diagram showing a control device according to an embodiment of the present disclosure.

[0016] Figure 2 is a schematic diagram showing an outline of contact detection by a control device according to an embodiment.

[0017] Explanation of Reference Signs

[0018] 1: Control device; 11: Period setting unit; 12: Voltage application unit; 13: Moving speed control unit; 14: Contact detection unit; 100: Wire electrical discharge machining machine; 101: Wire electrode; 102: Workpiece; 103: Moving drive unit; T1: First pulse period; T2: Second pulse period; V1: First relative moving speed; V2: Second relative moving speed. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Next, with reference to Figure 1 and Figure 2 a control device 1 and a program according to an embodiment of the present disclosure will be described.

[0020] First, before describing the control device 1 and the program according to an embodiment, a wire electrical discharge machining machine 100 controlled by the control device 1 will be described.

[0021] As Figure 1As shown, the wire electrical discharge machining apparatus 100 is, for example, an apparatus that machines a workpiece 102 by applying a machining voltage between electrodes of a wire electrode 101 and the workpiece 102. The wire electrical discharge machining apparatus 100 includes a movement drive unit 103 that relatively moves the wire electrode 101 and the workpiece 102. The movement drive unit 103 is constituted by, for example, a plurality of servo motors (not shown) disposed on respective axes of the wire electrode 101 and the workpiece 102. The movement drive unit 103 machines the workpiece 102 into a prescribed shape by relatively moving the wire electrode 101 and the workpiece 102. The movement drive unit 103 relatively moves the wire electrode 101 and the workpiece 102, for example, by moving a conductive worktable 104 on which the workpiece 102 is placed and the wire electrode 101. Further, in the following embodiments, for simplicity of explanation, an example in which the movement drive unit 103 moves the wire electrode 101 relative to the workpiece 102 will be described.

[0022] Next, measurement of the relative position between the wire electrode 101 and the workpiece 102 in the wire electrical discharge machining apparatus 100 will be described.

[0023] In the wire electrical discharge machining apparatus 100, when starting to machine the workpiece 102, measurement of the relative position between the wire electrode 101 and the workpiece 102 is performed. In the measurement of the relative position, first, a pulsed detection voltage having a level lower than the machining voltage is applied between the electrodes of the wire electrode 101 and the workpiece 102. Then, the wire electrode 101 and the workpiece 102 are moved in a direction of relative approach. Since the wire electrode 101 and the workpiece 102 come into contact, a change in the detection voltage is detected. Thereby, the positions of the wire electrode 101 and the workpiece 102 can be measured. Then, the wire electrical discharge machining apparatus 100 can machine the workpiece 102 into a prescribed shape with the measured position as a reference position.

[0024] Next, with reference to Figure 1 and Figure 2 a control device 1 and a program according to a first embodiment of the present disclosure will be described.

[0025] The control device 1 is a device that controls the wire electrical discharge machining apparatus 100. The control device 1 measures the relative position between the wire electrode 101 and the workpiece 102 by detecting contact between the relatively moving wire electrode 101 and the workpiece 102. In the present embodiment, the control device 1 detects contact between the wire electrode 101 and the workpiece 102 twice in the order of a first detection operation and a second detection operation. As Figure 1 shown, the control device 1 includes a cycle setting unit 11, a voltage application unit 12, a movement speed control unit 13, and a contact detection unit 14.

[0026] The cycle setting unit 11 is implemented by operating, for example, a CPU. The cycle setting unit 11 sets the pulse cycle of the detection voltage applied between the wire electrode 101 and the workpiece 102. The cycle setting unit 11 can change the pulse cycle of the detection voltage, for example, based on the pulse frequency input from the outside. In the present embodiment, as Figure 2 shown, the cycle setting unit 11 sets different pulse cycles in the first detection operation (act1) and in the second detection operation (act3). Specifically, the cycle setting unit 11 sets the second pulse cycle T2 in the second detection operation to be longer than the first pulse cycle T1 set in the first detection operation. The cycle setting unit 11 sets the second pulse cycle T2 set in the second detection operation to be, for example, 1.5 times or more of the first pulse cycle T1 set in the first detection operation.

[0027] The voltage application unit 12 is implemented by controlling, for example, a power supply (not shown) that applies the detection voltage by a CPU. The voltage application unit 12 applies the detection voltage between the electrodes at the set cycle. The voltage application unit 12 applies, for example, the detection voltage having the pulse cycle set by the cycle setting unit 11 between the electrodes. As Figure 2 shown, the voltage application unit 12 applies, for example, the detection voltage with the first pulse cycle T1 between the wire electrode 101 and the workpiece 102 in the first detection operation. In addition, the voltage application unit 12 applies the detection voltage with the second pulse cycle T2 between the wire electrode 101 and the workpiece 102 in the second detection operation.

[0028] The relative movement speed control unit 13 is implemented by operating, for example, a CPU. The relative movement speed control unit 13 controls the relative movement speed generated by the movement drive unit 103. The relative movement speed control unit 13 controls, for example, the relative movement speed between the wire electrode 101 and the workpiece 102 (workbench 104). In addition, the relative movement speed control unit 13 can change the relative movement speed, for example, based on the relative movement speed input from the outside. In the present embodiment, the relative movement speed control unit 13 controls different relative movement speeds in the first detection operation and in the second detection operation. Specifically, the relative movement speed control unit 13 controls the second relative movement speed V2 in the second detection operation to be slower than the first relative movement speed V1 in the first detection operation. In addition, after performing the first detection operation and before performing the second detection operation, the relative movement speed control unit 13 relatively moves the wire electrode 101 and the workpiece 102 in a direction away from each other ( Figure 2 act2).

[0029] The contact detection unit 14 is implemented by, for example, the CPU controlling a sensor (not shown). The contact detection unit 14 detects the contact between the wire electrode 101 and the workpiece 102 based on the change in the applied detection voltage. The contact detection unit 14 detects the contact between the wire electrode 101 and the workpiece 102, for example, by detecting the disappearance of the peak voltage. In addition, the contact detection unit 14 measures the position of the wire electrode 101 and the position of the workpiece 102 by detecting the contact. In the present embodiment, after performing the first detection operation for the contact between the wire electrode 101 and the workpiece 102 at the first relative movement speed V1 and the first pulse period T1, the contact detection unit 14 performs the second detection operation for the contact between the wire electrode 101 and the workpiece 102 at the second relative movement speed V2 slower than the first relative movement speed V1 and the second pulse period T2 longer than the first pulse period T1.

[0030] Next, the operation of the control device 1 according to the present embodiment will be described using Figure 2 Next, the operation of the control device 1 according to the present embodiment will be described.

[0031] First, when performing the first detection operation, the period setting unit 11 sets the first pulse period T1. Next, the movement speed control unit 13 sets the first relative movement speed V1.

[0032] Next, the voltage application unit 12 applies a detection voltage set to the first pulse period T1 between the poles of the wire electrode 101 and the workpiece 102. Next, the movement speed control unit 13 moves the wire electrode 101 in a direction approaching one end face S of the workpiece 102 at the first relative movement speed V1 (relative movement).

[0033] Next, the contact detection unit 14 detects the contact between the wire electrode 101 and the workpiece 102. The contact detection unit 14 measures the relative position between the wire electrode 101 and the workpiece 102. Thus, the first detection operation ends. Next, the movement speed control unit 13 moves the wire electrode 101 in a direction away from the workpiece 102 (relative movement). The movement speed control unit 13, for example, moves the wire electrode 101 away from the workpiece 102 by a distance shorter than the relative movement distance between the wire electrode 101 and the workpiece 102 in the first detection operation.

[0034] Next, when performing the second detection operation, the period setting unit 11 sets the second pulse period T2. Next, the movement speed control unit 13 sets the second relative movement speed V2.

[0035] Next, the voltage application unit 12 applies a detection voltage set to the second pulse period T2 between the wire electrode 101 and the workpiece 102. Next, the moving speed control unit 13 moves (relative movement) the wire electrode 101 in the direction approaching one end face S of the workpiece 102 at the second relative moving speed V2.

[0036] Next, the contact detection unit 14 detects the contact between the wire electrode 101 and the workpiece 102. The contact detection unit 14 measures the relative position between the wire electrode 101 and the workpiece 102. Thus, the second detection operation ends.

[0037] Next, the program of the present embodiment will be described.

[0038] Each structure included in the control device 1 can be implemented separately by hardware, software, or a combination thereof. Here, implementing by software means implementing by a computer reading and executing a program.

[0039] Programs can be stored using various types of non-transitory computer-readable media and provided to a computer. Non-transitory computer-readable media include tangible storage media of various types. Examples of non-transitory computer-readable media include magnetic recording media (such as floppy disks, magnetic tapes, hard disk drives), magneto-optical recording media (such as magneto-optical discs), CD-ROM (Read Only Memory), CD-R, CD-R / W, semiconductor memories (such as mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)). In addition, the display program can also be provided to a computer through various types of transitory computer-readable media. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. Transitory computer-readable media can provide the program to a computer via wired communication paths such as wires and optical fibers or wireless communication paths.

[0040] As described above, according to the control device 1 and the program according to the first embodiment, the following effects are achieved.

[0041] (1) A control device 1 for controlling a wire electrical discharge machining machine 100, the wire electrical discharge machining machine 100 having a moving drive unit 103 that relatively moves a wire electrode 101 and a workpiece 102. The control device 1 measures the relative position of the wire electrode 101 and the workpiece 102 by detecting the contact between the relatively moving wire electrode 101 and the workpiece 102. The control device 1 includes: a period setting unit 11 that sets the pulse period of a detection voltage applied between the wire electrode 101 and the workpiece 102; a voltage application unit 12 that applies the detection voltage between the electrodes at the set period; a moving speed control unit 13 that controls the relative moving speed generated by the moving drive unit 103; and a contact detection unit 14 that detects the contact between the wire electrode 101 and the workpiece 102 based on the change in the applied detection voltage. Among them, after performing a first detection operation for the contact between the wire electrode 101 and the workpiece 102 at a first relative moving speed V1 and a first pulse period T1, the contact detection unit 14 performs a second detection operation for the contact between the wire electrode 101 and the workpiece 102 at a second relative moving speed V2 slower than the first relative moving speed V1 and a second pulse period T2 longer than the first pulse period T1. Before performing the second detection operation after performing the first detection operation, the moving speed control unit 13 relatively moves the wire electrode 101 and the workpiece 102 in a direction away from each other.

[0042] In addition, a program for operating a computer as a control device 1 for controlling a wire electrical discharge machining machine 100 having a moving drive unit 103 for relatively moving a wire electrode 101 and a workpiece 102. The control device 1 measures the relative position of the wire electrode 101 and the workpiece 102 by detecting the contact between the relatively moving wire electrode 101 and the workpiece 102. The program causes the computer to function as the following units: a cycle setting unit 11 that sets a pulse cycle of a detection voltage applied between the wire electrode 101 and the workpiece 102; a voltage application unit 12 that applies the detection voltage between the electrodes at the set cycle; a relative movement speed control unit 13 that controls the relative movement speed generated by the moving drive unit 103; and a contact detection unit 14 that detects the contact between the wire electrode 101 and the workpiece 102 based on the change in the applied detection voltage. The contact detection unit 14 performs a second detection operation for the contact between the wire electrode 101 and the workpiece 102 at a second relative movement speed V2 slower than the first relative movement speed V1 and a second pulse cycle T2 longer than the first pulse cycle T1 after performing a first detection operation for the contact between the wire electrode 101 and the workpiece 102 at the first relative movement speed V1 and the first pulse cycle T1. Before performing the second detection operation after performing the first detection operation, the relative movement speed control unit 13 relatively moves the wire electrode 101 and the workpiece 102 in a separating direction.

[0043] Thus, in the first detection operation, the relative position of the wire electrode 101 and one end surface S of the workpiece 102 can be predicted in advance at the first pulse cycle T1 and the first relative movement speed V1. Moreover, in the second detection operation, the relative position of the wire electrode 101 and one end surface S of the workpiece 102 is measured at the second pulse cycle T2 and the second relative movement speed V2, thereby being able to suppress the generation of discharge marks on the workpiece 102. In addition, by using the detection voltage with the second pulse cycle T2, the influence of the bending of the wire electrode 101 can be suppressed. Therefore, by improving the detection accuracy of the contact between the wire electrode 101 and the workpiece 102, the measurement accuracy of the relative position of the wire electrode 101 and the workpiece 102 can be improved.

[0044] The preferred embodiments of the control device and the program of the present disclosure have been described above, but the present disclosure is not limited to the above embodiments and can be appropriately modified.

[0045] For example, in the above embodiments, examples using the first detection operation and the second detection operation have been described, but are not limited thereto. For example, measurements may also be performed using three or more detection operations. In this case, the later the detection operation is performed, the longer the pulse cycle and the slower the relative movement speed are used.

[0046] In addition, in the above-described embodiment, an example in which the wire electrode 101 is moved relative to the workpiece 102 has been described, but it is not limited thereto. It is also possible that both the workpiece 102 and the wire electrode 101 move relative to each other. It is also possible that the workpiece 102 moves while the wire electrode 101 does not move.

[0047] In addition, in the first detection operation, the first pulse period T1 and / or the first relative movement speed V1 may not be constant. In the second detection operation, the second pulse period T2 and / or the second relative movement speed V2 may not be constant.

[0048] In addition, in the above-described embodiment, it is assumed that the contact detection unit 14 performs the first detection operation and the second detection operation, but it is not limited thereto. As another embodiment, the contact detection unit 14 performs the detection operation two or more times, and in any of the detection operations after the second time, the contact between the wire electrode 101 and the workpiece 102 is detected at a speed slower than the relative movement speed of the wire electrode 101 and the workpiece 102 in the previous detection operation and at a pulse period longer than the pulse period in the previous detection operation. By doing so, it is also possible to improve the measurement accuracy of the relative position between the wire electrode 101 and the workpiece 102.

[0049] In addition, as another embodiment, the contact detection unit 14 may also perform multiple detection operations by slowing down the relative speed between the wire electrode 101 and the workpiece 102 and extending the pulse period in each detection operation. Thereby, it is possible to further improve the position detection accuracy of one end surface S of the workpiece 102. In addition, the movement speed control unit 13 relatively moves the wire electrode 101 and the workpiece 102 in a separating direction during each detection operation. At this time, the movement speed control unit 13 may also shorten the distance for separating the wire electrode 101 and the workpiece 102 as the number of detection operations increases. Thereby, even if the relative movement speed at which the wire electrode 101 and the workpiece 102 come into contact becomes slower as the number of detection operations increases, it is possible to suppress an increase in the time taken for the entire detection operation.

Claims

1. A control device for controlling a wire electrical discharge machining machine, the wire electrical discharge machining machine having a moving drive unit for relatively moving a wire electrode and a workpiece, the control device measuring the relative position between the wire electrode and the workpiece by detecting the contact between the relatively moving wire electrode and the workpiece, the control device comprising: a period setting unit that sets a pulse period of a detection voltage applied between the wire electrode and the workpiece; a voltage application unit that applies the detection voltage between the electrodes at the set period; a relative movement speed control unit that controls the relative movement speed generated by the moving drive unit; and a contact detection unit that detects the contact between the wire electrode and the workpiece based on a change in the applied detection voltage, wherein, after performing a first detection operation for the contact between the wire electrode and the workpiece at the first relative movement speed and the first pulse period, the contact detection unit performs a second detection operation for the contact between the wire electrode and the workpiece at a second relative movement speed slower than the first relative movement speed and a second pulse period longer than the first pulse period, before performing the second detection operation after performing the first detection operation, the relative movement speed control unit relatively moves the wire electrode and the workpiece in a separating direction.

2. The control device according to claim 1, characterized in that the contact detection unit performs two or more detection operations, and in any detection operation after the second time, detects the contact between the wire electrode and the workpiece at a speed slower than the relative movement speed between the wire electrode and the workpiece in the previous detection operation and at a pulse period longer than the pulse period in the previous detection operation.

3. The control device according to claim 1 or 2, characterized in that the period setting unit sets the pulse period set in the second detection operation to be 1.5 times or more of the pulse period set in the first detection operation.

4. A recording medium having a program recorded thereon, the program causing a computer to function as a control device for controlling a wire electrical discharge machining machine, the wire electrical discharge machining machine having a moving drive unit for relatively moving a wire electrode and a workpiece, the control device measuring the relative position between the wire electrode and the workpiece by detecting the contact between the relatively moving wire electrode and the workpiece, the program causing the computer to function as the following units: a period setting unit that sets a pulse period of a detection voltage applied between the wire electrode and the workpiece; a voltage application unit that applies the detection voltage between the electrodes at the set period; a relative movement speed control unit that controls the relative movement speed generated by the moving drive unit; and a contact detection unit that detects the contact between the wire electrode and the workpiece based on a change in the applied detection voltage, Among them, after the contact detection unit performs a first detection operation for the contact between the wire electrode and the workpiece at the first relative movement speed and the first pulse period, the contact detection unit performs a second detection operation for the contact between the wire electrode and the workpiece at a second relative movement speed slower than the first relative movement speed and a second pulse period longer than the first pulse period. After performing the first detection operation and before performing the second detection operation, the movement speed control unit relatively moves the wire electrode and the workpiece in a direction away from each other.

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