Diagnosis device for power supply device of electric discharge machine

Abstract

An analog current generating section (13) is connected in series with the power supply device (2) for electric discharge machining in a state where the contact (11) and the contact (12) are in contact, and generates an analog current (I sim ) that simulates a current generated by breakdown of insulation between electrodes composed of a workpiece (5) and a tube electrode (7) that are arranged to face each other with a predetermined gap provided therebetween, on the basis of an applied voltage of the power supply device (2) for electric discharge machining, in order to perform electric discharge machining on the workpiece (5) by the fine-hole electric discharge machining device (6). An NC device (20) performs determination of the presence or absence of an abnormality in the power supply device (2) for electric discharge machining on the basis of the analog current (I sim ) detected by a current detecting section (15).

Description

Technical Field

[0001] This invention relates to a diagnostic device for the power supply unit of an electrical discharge machining (EDM) machine. Background Technology

[0002] To perform electrical discharge machining (EDM) on workpieces (such as fine-hole EDM and EDM forming), a power supply device for an EDM machine is used to apply a pulse voltage between electrodes consisting of a workpiece and electrodes facing each other at a predetermined gap. This power supply device includes: a DC power supply connected in series between the electrodes to apply a voltage for generating current; and a switching element disposed between the electrodes and the DC power supply, with a cable running between the electrodes and the switching element.

[0003] In the past, an electrical discharge machining (EDM) machine was proposed that detects the level of discharge voltage, discharge current, or impedance between electrodes during workpiece machining. When the detected level of discharge voltage, discharge current, or impedance does not meet specified conditions, it is determined that an abnormal discharge has occurred (e.g., Patent Document 1). In such an EDM machine, in order to avoid the occurrence of defective products, normal discharge is initiated after the abnormal discharge is removed.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent document: Japanese Patent Application Publication No. 61-293717 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, in older electrical discharge machining (EDM) machines, if there were malfunctions or other abnormalities in the power supply, normal discharge could not be generated even after the abnormal discharge that occurred during workpiece machining was removed. Therefore, when EDM was performed on a workpiece using an EDM machine with a faulty power supply, defective products could not be avoided.

[0009] The purpose of this invention is to provide a diagnostic device for the power supply of an electrical discharge machining (EDM) machine. This diagnostic device can diagnose whether there are any abnormalities in the power supply of the EDM machine before the EDM machine is used to process the workpiece.

[0010] Methods for solving problems

[0011] According to the diagnostic device for an electrical discharge machining (EDM) power supply, in order to perform EDM on a workpiece using an EDM machine, the EDM power supply applies a pulse voltage between electrodes consisting of a workpiece and electrodes facing each other with a predetermined gap. The diagnostic device includes: a first contact that is conductive to one side of the EDM power supply via a conductive part of the EDM machine; a second contact that is conductive to the other side of the EDM power supply via a conductive part of a worktable on which the workpiece is disposed, and is capable of contacting or separating from the first contact; a simulated current generating unit connected in series with the EDM power supply while the first and second contacts are in contact, generating a simulated current based on the applied voltage of the EDM power supply to simulate the current generated due to insulation failure between the electrodes; and a determination unit that detects the simulated current and determines whether there is an abnormality in the EDM power supply based on the simulated current.

[0012] According to the present invention, a simulated current generating unit, connected in series with a power supply device for an electrical discharge machining (EDM) machine while the first and second contacts are in contact, generates a simulated current based on the applied voltage of the power supply device, simulating the current generated due to insulation failure between the electrodes. Furthermore, a determination unit detects the simulated current and determines whether there is any abnormality in the power supply device based on the simulated current. Since the determination of whether there is any abnormality in the power supply device is based on the simulated current simulating the current generated due to insulation failure between the electrodes, it is possible to diagnose whether there is any abnormality in the power supply device before performing EDM on a workpiece.

[0013] Furthermore, according to the present invention, by diagnosing any abnormalities in the power supply of the EDM machine before performing EDM on a workpiece, and if an abnormality is found in the power supply, repairs can be made to the faulty parts of the power supply, or the power supply can be replaced. Since repairing the faulty parts of the power supply or replacing it ensures its proper functioning, defects caused by using an EDM machine with a faulty power supply can be avoided.

[0014] Furthermore, according to the present invention, defective products generated when EDM is performed on a workpiece using an EDM power supply with a malfunctioning power supply can be avoided. Therefore, it is unnecessary to interrupt workpiece processing and handle defective products by conducting inspections when defective products are generated during EDM using an EDM power supply with a malfunctioning power supply. Additionally, electrode wear can be avoided when defective products are generated during EDM using an EDM power supply with a malfunctioning power supply.

[0015] Preferably, the determination unit determines whether there is any abnormality in the power supply device for the electrical discharge machining (EDM) machine based on at least one of the average current of the simulated current and the on-time and off-time of the simulated current. By determining whether there is any abnormality in the power supply device for the EDM machine based on at least one of the on-time and off-time of the simulated current and the average current of the simulated current, it is possible to accurately diagnose whether there is any abnormality in the power supply device for the EDM machine before the EDM machine is used to process the workpiece.

[0016] Preferably, before generating the simulated current, the determination unit detects a simulated voltage generated by the power supply device for the electrical discharge machine before the insulation between the electrodes breaks down, either when the first and second contacts are in contact or when the first and second contacts are not in contact. Based on the simulated voltage, it determines whether there is any abnormality in the power supply device for the electrical discharge machine. Therefore, it is possible to diagnose any abnormalities in the power supply device for the electrical discharge machine before generating the simulated current.

[0017] Preferably, the determination unit determines whether there is an abnormality in the power supply device for the electrical discharge machine based on at least one of the peak voltage and the rise time of the analog voltage. By determining whether there is an abnormality in the power supply device for the electrical discharge machine based on at least one of the peak voltage and the rise time of the analog voltage, the diagnosis of whether there is an abnormality in the power supply device for the electrical discharge machine can be performed correctly before the analog current is generated.

[0018] Preferably, the simulated current generating unit has a resistor connected in series with the power supply unit for the electrical discharge machine, and the resistor has a resistance value equivalent to the resistance between the electrodes when insulation failure occurs. By using such a resistor, the simulated current can accurately simulate the current generated due to insulation failure between the electrodes.

[0019] Preferably, the analog current generating unit also includes a switching element connected in series with a resistor. When generating an analog voltage, the NC device of the EDM machine keeps the switching element in the open state, and when generating an analog current, the NC device of the EDM machine keeps the switching element in the closed state. By using such a switching element, analog voltage and analog current can be generated rapidly.

[0020] Preferably, the switching element is a contact switch. By using a contact switch as the switching element, the deviation in determining whether there is an abnormality in the power supply device for the EDM machine can be reduced.

[0021] Preferably, the determination unit determines whether there is poor contact between the first contact and the second contact. In this way, by determining whether there is poor contact between the first contact and the second contact, the poor contact area between the first contact and the second contact can be repaired if there is poor contact.

[0022] Preferably, the determination unit determines whether the switching element is malfunctioning. In this way, by determining whether the switching element is malfunctioning, the switching element can be replaced if a malfunction is found. Attached Figure Description

[0023] Figure 1 This is a diagram showing a system having a diagnostic device for a power supply device for an electrical discharge machine according to an embodiment of the present invention.

[0024] Figure 2 It means by Figure 1 A diagram showing the analog voltage detected by the diagnostic device of the power supply unit for an electrical discharge machining (EDM) machine.

[0025] Figure 3 It means by Figure 1 A diagram of the analog current detected by the diagnostic device of the power supply unit for an electrical discharge machining (EDM) machine.

[0026] Figure 4 It is a flowchart used to explain the process of determining whether a contact switch is malfunctioning or whether the contacts are making poor contact.

[0027] Figure 5 This is a flowchart used to explain the judgment process for determining whether there is any malfunction in the power supply device for an EDM machine based on whether the contact switch is malfunctioning and whether there is any abnormality in the analog voltage.

[0028] Figure 6 This is a flowchart used to explain the judgment process for determining whether there is any malfunction in the power supply device for an EDM machine based on whether the contact switch is malfunctioning and whether there is any abnormality in the simulated current.

[0029] Figure 7This is a diagram showing a system having a diagnostic device for a power supply device for an electrical discharge machine according to another embodiment of the present invention.

[0030] Specific implementation method

[0031] Hereinafter, embodiments of the diagnostic device for the power supply of an electrical discharge machine according to the present invention will be described in detail with reference to the accompanying drawings.

[0032] Figure 1 This is a diagram illustrating a system having a diagnostic device for a power supply unit for an electrical discharge machining (EDM) machine according to an embodiment of the present invention. Figure 1 In this system, diagnostic device 1 diagnoses whether there are any abnormalities in the power supply unit 2 for the electrical discharge machine. That is, diagnostic device 1 determines whether there are any abnormalities in the power supply unit 2 for the electrical discharge machine, and if an abnormality is found, generates and displays an alarm indicating that an abnormality exists in the power supply unit 2. Diagnostic device 1 is an example of a diagnostic device for the power supply unit of an electrical discharge machine.

[0033] The power supply unit 2 for the electrical discharge machining (EDM) machine utilizes a fine-hole EDM machine 6 to perform EDM machining on a workpiece 5 placed on a worktable 4 immersed in EDM fluid in a machining tank 3. Therefore, the power supply unit 2 applies pulse voltages via cable 8 to the electrode gap formed by the workpiece 5 and the tube electrode 7, which are positioned opposite each other at a predetermined gap. The fine-hole EDM machine 6 is an example of an EDM machine. The tube electrode 7 is an example of an electrode.

[0034] The power supply unit 2 for the electrical discharge machining (EDM) machine includes a DC power supply (not shown) and a switching element such as an NMOS transistor (not shown). A pulse signal is input to the switching element of the power supply unit 2. This pulse signal is generated by the pulse generation circuit 9 based on pulse generation conditions corresponding to the machining conditions set for the workpiece 5 (in this case, fine-hole EDM) and diagnostic conditions, which will be explained later. The switching element of the power supply unit 2 controls the supply of power from the DC power supply unit 2 to the fine-hole EDM machine 6 according to the pulse signal. The machining conditions set for the workpiece 5 are determined in relation to the material of the workpiece 5, the material of the tube electrode 7, and the machining shape of the workpiece 5. The pulse generation conditions include the pulse on / off time of the pulse train, the number of pulses in the pulse train, and the pulse rest time.

[0035] In the machining tank 3, in addition to the worktable 4, a support 21 is arranged. An insulating part 22 is provided at the upper end of the support 21. The worktable 4 has: an inclined worktable 23 that can rotatably support the workpiece 5 along arrow A, a rotary worktable 24 that can rotatably support the workpiece 5 along arrow B, and a conductive part 25 made of conductive material and provided on the rotary worktable 24.

[0036] The fine-hole EDM machine 6 is configured to perform EDM on workpiece 5. The fine-hole EDM machine 6 is equipped with: a spindle assembly 32, on which an electrode holder 31 is mounted; a guide arm 34, in which a power supply cable 33 is built-in; and a power supply socket 35, which is mounted on the front end of the guide arm 34 for direct contact and power supply to the tube electrode 7, thereby being electrically connected to the power supply cable 33. The electrode holder 31 holds the tube electrode 7. Furthermore, the power supply cable 33 is connected to a cable 8, one end of which is connected to one side of the power supply unit 2 for the EDM machine (e.g., the positive side of the DC power supply of the power supply unit 2 for the EDM machine). The power supply cable 33 and the power supply socket 35 are examples of conductive parts of the EDM machine.

[0037] The spindle assembly 32 can move along the X, Y, and Z axes of the three-dimensional coordinate system by means of the servo motor (not shown) of the fine-hole EDM machine 6. The guide arm 34 and the power supply base 35 can move relative to the spindle assembly 32 along the W axis, which is a movement axis parallel to the Z axis, in the a or b direction, by means of the servo motor of the fine-hole EDM machine 6.

[0038] The diagnostic device 1 is equipped with contacts 11 and 12, an analog current generation unit 13, an operational amplifier 14 as a voltage detection unit, a current detection unit 15, an analog-to-digital converter (ADC) 16 and 17, an arithmetic unit 18 and 19, and an NC device 20.

[0039] Contact 11 is mounted on power supply base 35 and is connected to one side of power supply device 2 for EDM machine via power supply line 33, power supply base 35 and cable 8.

[0040] The contact 12 is disposed on the insulating part 22 and can be connected to the other side of the power supply device 2 for the electrical discharge machine (e.g., the negative side of the DC power supply of the power supply device 2 for the electrical discharge machine) via the conductive part 25. The conductive part 25 is an example of the conductive part of the worktable.

[0041] After the spindle assembly 32 moves along the X, Y, and Z axes directly above the bracket 21, it moves along the W axis in either the a or b direction via the contact 11, guide arm 34, and power supply base 35. The contact 11 and contact 12 move relative to each other. Thus, the contact 12 can contact or separate from the contact 11.

[0042] When contacts 11 and 12 are in contact, the analog current generating unit 13 is connected in series with the power supply unit 2 for the electrical discharge machine. The analog current generating unit 13 has a contact switch 13a and a resistor 13b. The contact switch 13a and the resistor 13b are connected in series. The contact switch 13a is an example of a switching element. The resistor 13b, connected in series with the power supply unit 2 for the electrical discharge machine, has a resistance value equivalent to the resistance value between the workpiece 5 and the tube electrode 7 when insulation failure occurs between the electrodes.

[0043] In this embodiment, when contact 11 and contact 12 are in contact and contact switch 13a is in the closed state, the analog current generating unit 13 generates an analog current I based on the voltage applied to the analog current generating unit 13 by the power supply device 2 for the electrical discharge machine. sim Simulated current I sim It is a current that simulates the current generated by the breakdown of insulation between electrodes.

[0044] The voltage detection unit detects the voltage before and after the power supply unit 2 for the electrical discharge machine via operational amplifier 14. Operational amplifier 14 is connected in parallel with the power supply unit 2 for the electrical discharge machine and has a non-inverting input section, an inverting input section, and an output section connected to the input section of ADC 16.

[0045] In this embodiment, when contact 11 and contact 12 are in contact and contact switch 13a is in the open state, operational amplifier 14, which is a voltage detection unit, detects the simulated voltage V that simulates the voltage between electrodes before insulation failure generated by the power supply device 2 for the electrical discharge machine. sim Furthermore, operational amplifier 14 will detect the analog voltage V. sim The output is sent to the input section of the ADC16.

[0046] The current detection unit 15 includes a shunt resistor 15a and a current readout amplifier 15b. The shunt resistor 15a is connected between the conductive part 25 and the power supply unit 2 for the electrical discharge machine. The current readout amplifier 15b amplifies the voltage across the shunt resistor 15a, which corresponds to the value of the current flowing in the resistor 13b, and outputs it to the input of the ADC 17.

[0047] In this embodiment, when contact 11 and contact 12 are in contact and contact switch 13a is in the closed state, the current detection unit 15 detects the simulated current I that simulates the current generated due to the insulation failure between the electrodes. sim The value corresponds to the voltage across the shunt resistor 15a. Furthermore, the current detection unit 15 outputs the detected voltage to the input section of the ADC 17.

[0048] ADC16 will detect the analog voltage V from operational amplifier 14, which is used as the voltage detection unit. sim Perform analog-to-digital conversion, converting the analog voltage V to digital. sim The output is sent to the arithmetic unit 18. The ADC17 performs analog-to-digital conversion on the voltage detected by the current detection unit 15 and outputs the converted voltage to the arithmetic unit 19.

[0049] The arithmetic units 18 and 19 are, for example, constructed from a field-programmable gate array (FPGA). The arithmetic unit 18 calculates the analog voltage V. sim Peak voltage and analog voltage V sim The rise time. Based on a table representing the relationship between voltage and current stored in the storage unit (not shown) of the arithmetic unit 19, the arithmetic unit 19 converts the voltage value output from the current readout amplifier 15b into a current value, thereby obtaining the analog current I. sim The value of .

[0050] Furthermore, the arithmetic unit 19 calculates the analog current I. sim Average current and analog current I sim The on and off times will simulate the current I. sim Average current and analog current I sim The on-time and off-time data are provided to the arithmetic unit 18. The arithmetic unit 18 then processes the analog voltage V. sim Peak voltage, analog voltage V sim Rise time of analog current I sim Average current and analog current I sim The data on the turn-on and turn-off times are provided to the NC device 20.

[0051] The NC device 20 reads and interprets the NC program containing machining condition settings from its storage unit (not shown), and provides the machining condition settings to the pulse generation circuit 9. Furthermore, the NC device 20 controls the servo motors driving the spindle assembly 32 in the X, Y, and Z axes, and the servo motors driving the guide arm 34 and power supply base 35 in the W axis direction. Additionally, the NC device 20 controls the open or closed state of the contact switch 13a.

[0052] In this embodiment, the NC device 20 is based on the analog voltage V sim Peak voltage, analog voltage V sim Rise time, analog current I sim Average current and analog current I simThe system uses data on the on and off times to determine whether there is any abnormality in the power supply unit 2 for the electrical discharge machine. Specifically, the storage unit of the NC device 20 stores a computer program, which will be described later, for determining whether there is any abnormality in the power supply unit 2 for the electrical discharge machine as described above. The NC device 20 may also be equipped with circuitry for determining whether there is any abnormality in the power supply unit 2 for the electrical discharge machine as described above. An example of a determination unit is a combination of the operational amplifier 14 (voltage detection unit), the current detection unit 15, the ADCs 16 and 17, the arithmetic units 18 and 19, and the NC device 20.

[0053] Figure 2 It means to utilize Figure 1 A diagram showing the analog voltage detected by the diagnostic device of the power supply unit for an electrical discharge machining (EDM) machine. The NC device 20 determines the analog voltage V. sim Peak voltage V p Whether the value is within a predetermined range. For example, NC device 20 determines whether the peak voltage V is within a predetermined range. p Whether the value is above 95% and below 105% of the predetermined reference value of the peak voltage. In the analog voltage V sim Peak voltage V p If the value is within a predetermined range, the NC device 20 determines that there is no abnormality in the power supply device 2 for the electrical discharge machine. In contrast, when the analog voltage V... sim Peak voltage V p If the value is outside the predetermined range, the NC device 20 determines that there is an abnormality in the power supply unit 2 for the electrical discharge machine. Furthermore, the NC device 20 stops the operation of the fine-hole electrical discharge machine 6 and displays an alarm indicating an abnormality in the power supply unit 2 for the electrical discharge machine on the display unit of the NC device 20 (not shown in the figure). The display unit of the NC device 20 is, for example, a touch screen display.

[0054] In addition, the NC device 20 determines the analog voltage V sim rise time t r Whether it is within the predetermined range. For example, NC device 20 determines the rise time t. r Is it above 95% and below 105% of the predetermined baseline value for the rise time? At rise time t r Within the predetermined range, the NC device 20 determines that there is no abnormality in the power supply device 2 for the electrical discharge machine. In contrast, during the rise time t... r If the operation is outside the predetermined range, the NC device 20 determines that there is an abnormality in the power supply unit 2 for the electrical discharge machine. Furthermore, the NC device 20 stops the operation of the fine-hole electrical discharge machine 6 and displays an alarm indicating an abnormality in the power supply unit 2 for the electrical discharge machine on the display screen of the NC device 20.

[0055] Figure 3 It means by Figure 1 A diagram showing the analog current detected by the diagnostic device of the power supply unit for an electrical discharge machining (EDM) machine. The NC device 20 determines the analog current I. sim The average current value I AVR Whether it is within a predetermined range. For example, the NC device 20 determines the value of the average current I. AVR Is it above 95% and below 105% of the predetermined reference value of the average current? At the average current value I... AVR Within the predetermined range, the NC device 20 determines that there is no abnormality in the power supply device 2 for the electrical discharge machine. In contrast, at the average current value I... AVR If the operation is outside the predetermined range, the NC device 20 determines that there is an abnormality in the power supply unit 2 for the electrical discharge machine. Furthermore, the NC device 20 stops the operation of the fine-hole electrical discharge machine 6 and displays an alarm indicating an abnormality in the power supply unit 2 for the electrical discharge machine on the display screen of the NC device 20.

[0056] In addition, the NC device 20 determines the analog current I. sim Connection time t on and shutdown time t off Whether both are within a predetermined range. For example, NC device 20 determines the analog current I. sim Connection time t on Whether it is above 95% and below 105% of the predetermined reference value of the turn-on time, and whether the analog current I sim Off time t off Whether it is above 95% and below 105% of the predetermined reference value of the turn-off time. In the analog current I... sim Connection time t on and shutdown time t off If both are within the predetermined range, the NC device 20 determines that there is no abnormality in the power supply device 2 for the electrical discharge machine. In contrast, when the simulated current I... sim Connection time t on and shutdown time t off If at least one of these conditions is not within the predetermined range, the NC device 20 determines that there is an abnormality in the power supply device 2 for the electrical discharge machine. Furthermore, the NC device 20 stops the operation of the fine-hole electrical discharge machine 6 and displays an alarm indicating an abnormality in the power supply device 2 for the electrical discharge machine on the display unit of the NC device 20.

[0057] Figure 4This is a flowchart illustrating the process of determining whether a contact switch is malfunctioning or whether the contacts are making poor contact. The NC device 20 implements this process based on a computer program stored in its storage unit that determines whether a contact switch is malfunctioning or whether the contacts are making poor contact. Additionally, the process is based on an analog voltage V... sim Before determining whether there is any abnormality in the power supply device for the electrical discharge machine, the process begins with the contacts 11 and 12 separated.

[0058] First, the NC device 20 puts the contact switch 13a in the open state (step S1). Next, the NC device 20 moves the contact 11 so that the contact 11 is in contact with the contact 12 by moving the guide arm 34 and the power supply base 35 along the W axis in the a direction (step S2).

[0059] Next, the NC device 20 determines whether the path from one side of the power supply unit 2 for the electrical discharge machine is in a conductive state (step S3). For example, the determination of whether the path from one side of the power supply unit 2 for the electrical discharge machine is in a conductive state is based on the current of the voltage applied to the analog current generating unit 13 by the power supply unit 2 for the electrical discharge machine. Specifically, the determination is made as to whether the value of the current of the voltage applied to the analog current generating unit 13 by the power supply unit 2 for the electrical discharge machine is 0. When a pulse signal generated by the pulse generating circuit 9 is input to the power supply unit 2 for the electrical discharge machine based on the instruction of the NC device 20, the voltage applied to the analog current generating unit 13 by the power supply unit 2 for the electrical discharge machine is generated.

[0060] If the path from one side of the power supply unit 2 for the electrical discharge machine is open, that is, if the current value based on the voltage applied to the analog current generation unit 13 by the power supply unit 2 for the electrical discharge machine is not zero ("Yes" in step S3), the NC device 20 determines that there is a malfunction in the contact switch. Furthermore, the NC device 20 stops the operation of the fine-hole electrical discharge machine 6 and displays an alarm indicating a malfunction in the contact switch on the display unit of the NC device 20 (step S4). Then, the NC device 20 terminates the process.

[0061] When the path from one side of the power supply unit 2 for the electrical discharge machine is not in a conductive state, that is, when the current value based on the voltage applied to the analog current generation unit 13 by the power supply unit 2 for the electrical discharge machine is 0 ("No" in step S3), the NC device 20 puts the contact switch 13a in the closed state (step S5).

[0062] Next, the NC device 20 determines whether the path from one side of the power supply device 2 for the electrical discharge machine is in a conductive state (step S6). The determination performed in step S6 is the same as the determination performed in step S3.

[0063] If the path from one side of the power supply unit 2 for the electrical discharge machine is not conductive ("No" in step S6), that is, if the current value based on the voltage applied to the analog current generation unit 13 by the power supply unit 2 for the electrical discharge machine is 0, the NC device 20 determines that there is a malfunction of the contact switch or a poor contact of the contacts. Furthermore, the NC device 20 stops the operation of the fine-hole electrical discharge machine 6 and displays an alarm indicating a malfunction of the contact switch or a poor contact of the contacts on the display unit of the NC device 20 (step S7). After step S7, the NC device 20 ends the process.

[0064] When the path from one side of the power supply unit 2 for the electrical discharge machine is open, that is, when the value of the current applied to the analog current generation unit 13 based on the voltage of the power supply unit 2 for the electrical discharge machine is not zero ("Yes" in step S6), the NC device 20 sets diagnostic conditions (step S8). The diagnostic conditions are the magnitude of the applied voltage and the magnitude of the supplied current of the power supply unit 2, which are set corresponding to the type of machining (finishing, roughing, fine-hole electrical discharge machining, etc.) performed after diagnosing whether there is an abnormality in the power supply unit for the electrical discharge machine. After step S8, the NC device 20 ends the process.

[0065] Figure 5 This is a flowchart illustrating the process of determining whether there is a malfunction in the power supply unit of an EDM machine based on the presence or absence of contact switch malfunctions and analog voltage. This process is implemented by the NC device 20 based on a computer program that determines whether there is a malfunction in the power supply unit of the EDM machine based on the presence or absence of contact switch malfunctions and analog voltage. Furthermore, after the NC device 20 sets the diagnostic conditions, the process begins with contacts 11 and 12 in contact.

[0066] First, the NC device 20 opens the contact switch 13a (step S11). Next, the NC device 20 sends a pulse signal input command to the pulse generation circuit 9. This pulse signal input command generates an analog voltage V based on the applied voltage of the power supply device 2 for the electrical discharge machine to the analog current generation unit 13. sim The pulse signal input instruction is given to the power supply unit 2 of the EDM machine (step S12). The pulse signal input instruction sent in step S12 is set based on diagnostic conditions.

[0067] Next, the NC device 20 determines whether the value of the current applied to the analog current generation unit 13 based on the voltage of the power supply device 2 for the electrical discharge machine is 0 (step S13). If the value of the current applied to the analog current generation unit 13 based on the voltage of the power supply device 2 for the electrical discharge machine is not 0 ("No" in step S13), the NC device 20 determines that there is a malfunction in the contact switch. Furthermore, the NC device 20 stops the operation of the fine-hole electrical discharge machine 6 and displays an alarm indicating a malfunction in the contact switch on the display unit of the NC device 20 (step S14). After step S14, the NC device 20 ends the process.

[0068] When the value of the current applied to the analog current generation unit 13 by the power supply unit 2 for the electrical discharge machine is 0 ("Yes" in step S13), the NC device 20 obtains the analog voltage V from the arithmetic unit 18. sim Peak voltage V p and rise time t r (Step S15).

[0069] Next, the NC device 20 sends a pulse signal stop command to the pulse generation circuit 9. The pulse signal stop command stops inputting the analog voltage V generated by the power supply device 2 for the analog current generation unit 13 based on the applied voltage of the power supply device 2 for the EDM machine. sim The pulse signal means the instruction (step S16). Based on the diagnostic conditions, the pulse signal stop instruction sent in step S16 is set. Next, the NC device 20 will send the analog voltage V... sim Peak voltage V p and rise time t r Record it in the storage unit of NC device 20 (step S17).

[0070] Next, the NC device 20 is based on the analog voltage V sim Peak voltage V p and rise time t r The NC device 20 determines whether there is an abnormality in the power supply unit 2 for the electrical discharge machining (EDM) (step S18). If there is an abnormality in the power supply unit 2 ("Yes" in step S18), the NC device 20 determines that there is an abnormality in the power supply unit 2. Furthermore, the NC device 20 stops the operation of the fine-hole EDM machine 6 and displays an alarm indicating that there is an abnormality in the power supply unit 2 on the display unit of the NC device 20 (step S19). After step S19, the NC device 20 ends the process. If there is no abnormality in the power supply unit 2 ("No" in step S18), the NC device 20 ends the process.

[0071] Figure 6 This is a flowchart illustrating the process of determining whether there is a malfunction in the contact switch and whether there is an abnormality in the power supply unit of the EDM machine based on the simulated current. The NC device 20 implements this process based on a computer program used to determine whether there is an abnormality in the power supply unit of the EDM machine based on the malfunction in the contact switch and the simulated current. Furthermore, in Figure 5 In step S18 of the flowchart, after determining that there is no abnormality in the power supply device 2 for the electrical discharge machine, the process begins with the contacts 11 and 12 in contact.

[0072] First, the NC device 20 closes the contact switch 13a (step S21). Next, the NC device 20 sends a pulse signal input command to the pulse generation circuit 9. This pulse signal input command generates an analog current I based on the applied voltage of the power supply device 2 for the electrical discharge machine to the analog current generation unit 13. sim The pulse signal input is a command given to the power supply unit 2 of the electrical discharge machine. The pulse signal input command sent in step S22 is set based on diagnostic conditions.

[0073] Next, the NC device 20 determines whether the current value based on the voltage applied to the analog current generation unit 13 by the power supply device 2 for the electrical discharge machine is 0 (step S23). If the current value based on the voltage applied to the analog current generation unit 13 by the power supply device 2 for the electrical discharge machine is 0 ("Yes" in step S13), the NC device 20 determines that there is a malfunction of the contact switch or poor contact of the contacts. Furthermore, the NC device 20 stops the operation of the fine-hole electrical discharge machine 6 and displays an alarm indicating that there is a malfunction of the contact switch or poor contact of the contacts on the display unit of the NC device 20 (step S24). After step S24, the NC device 20 ends the process.

[0074] If the value of the current applied to the analog current generation unit 13 by the power supply device 2 for the electrical discharge machine is not 0 ("No" in step S23), the NC device 20 obtains the analog current I from the arithmetic unit 18. sim Connection time t on and shutdown time t off and the value of average current I AVR (Step S25).

[0075] Next, the NC device 20 sends a pulse signal stop command to the pulse generation circuit 9. The pulse signal stop command stops inputting analog current I to the power supply unit 2 for the electrical discharge machine, which is used to generate analog current I based on the voltage applied to the analog current generation unit 13 by the power supply unit 2 for the electrical discharge machine. simThe pulse signal means the instruction (step S26). The pulse signal stop instruction sent in step S26 is set based on diagnostic conditions. After step S26, the NC device 20 will simulate current I... sim Connection time t ON and shutdown time t OFF and the value of average current I AVR Record it in the storage unit of NC device 20 (step S27).

[0076] Next, the NC device 20 is based on the analog current I sim The average current value I AVR and connection time t ON and shutdown time t OFF The system determines whether there is an abnormality in the power supply unit 2 for the electrical discharge machining (EDM) (step S28). If an abnormality exists in the power supply unit 2 (yes in step S28), the NC device 20 determines that there is an abnormality in the power supply unit 2. Furthermore, the NC device 20 stops the operation of the fine-hole EDM machine 6 and displays an alarm indicating an abnormality in the power supply unit 2 on the display unit of the NC device 20 (step S29). After step S29, the NC device 20 ends the process. If there is no abnormality in the power supply unit 2 (no in step S28), the NC device 20 ends the process. Figure 6 In step S28 of the flowchart, if it is determined that there is no abnormality in the power supply device 2 for the electrical discharge machine, the electrical discharge machining of the workpiece 5 by the fine hole electrical discharge machine 6 can begin.

[0077] According to this embodiment, when the contact 11 and the contact 12 are in contact, the simulated current generation unit 13 generates a simulated current I based on the applied voltage of the power supply device 2 for the electrical discharge machine to simulate the current generated due to the insulation failure between the electrodes. sim Furthermore, the NC device 20 is based on analog current I. sim A determination is made regarding whether there are any abnormalities in the power supply unit 2 for the electrical discharge machine. This is based on a simulated current I, which simulates the current generated due to insulation failure between electrodes. sim Therefore, before the fine-hole EDM machine 6 performs EDM on the workpiece 5, it is possible to determine whether there is any abnormality in the power supply device 2 of the EDM machine.

[0078] Furthermore, according to this embodiment, before performing electrical discharge machining (EDM) on the workpiece 5 using the fine-hole EDM machine 6, a diagnostic check is performed to determine if there are any abnormalities in the power supply unit 2 for the EDM machine. If an abnormality is found in the power supply unit 2, repairs can be made to the faulty parts of the power supply unit 2, or the power supply unit can be replaced. By repairing the faulty parts of the power supply unit 2 or replacing the power supply unit, the power supply unit 2 can be used normally. Therefore, it is possible to avoid producing defective products due to EDM machining of the workpiece 5 using the fine-hole EDM machine 6 with an abnormal power supply unit 2.

[0079] Furthermore, according to this embodiment, defective products can be avoided when the workpiece 5 is processed by the fine-hole EDM machine 6, which has a faulty power supply unit 2, due to EDM power supply failure. Therefore, it is unnecessary to interrupt the processing of the workpiece 5 and to handle defective products when inspection is performed on the workpiece 5 due to the faulty power supply unit 2. Additionally, the consumption of the tube electrode 7 can be avoided when defective products are produced when the workpiece 5 is processed by the fine-hole EDM machine 6, which has a faulty power supply unit 2.

[0080] Furthermore, according to this embodiment, based on analog current I sim The average current value I AVR and connection time t ON and shutdown time t OFF The power supply unit 2 for the electrical discharge machining (EDM) machine is checked for any abnormalities. Therefore, before performing EDM on the workpiece 5 using the fine-hole EDM machine 6, the abnormalities of the power supply unit 2 for the EDM machine can be correctly diagnosed.

[0081] Furthermore, according to this embodiment, by using analog voltage V sim To determine whether there are any abnormalities in the power supply unit of the electrical discharge machining (EDM) machine, a simulated current I can be generated. sim Previously, a diagnostic check was performed to determine if there were any abnormalities in the power supply unit used in the electrical discharge machining (EDM) machine.

[0082] Furthermore, according to this embodiment, by using analog voltage V sim Peak voltage V p and rise time t r To determine whether there are any abnormalities in the power supply unit of the electrical discharge machining (EDM) machine, a simulated current I can be generated. sim Previously, it was necessary to properly diagnose any abnormalities in the power supply unit used in the electrical discharge machining (EDM) machine.

[0083] Furthermore, according to this embodiment, by using a resistor 13b having a resistance value equivalent to the inter-electrode resistance value when insulation failure occurs, the simulated current I is obtained. sim It can accurately simulate the current generated by the breakdown of insulation between poles.

[0084] Furthermore, according to this embodiment, by using the generation of analog voltage V sim It is in the open state and generating analog current I sim When the contact switch 13a is in the closed state, it can quickly generate an analog voltage V. sim and simulated current I sim .

[0085] Furthermore, according to this embodiment, by using the contact switch 13a, the deviation in determining whether there is an abnormality in the power supply device 2 for the electrical discharge machine can be reduced.

[0086] Furthermore, according to this embodiment, by determining whether there is poor contact between the first contact and the second contact, if there is poor contact between the first contact and the second contact, the part with poor contact between the first contact and the second contact can be repaired.

[0087] Furthermore, according to this embodiment, by determining whether there is a malfunction in the contact switch 13a, the contact switch 13a can be replaced if there is a malfunction in the contact switch 13a.

[0088] This invention is not limited to the embodiments described above, and various modifications and variations are possible. For example, the conductive part 25 can be placed at any position on the worktable 4. Furthermore, to enable the contacts 11 and 12 to contact or separate, the support 21, which houses the contacts 12 via the insulating part 22, can be freely moved in either direction a or b, allowing the contacts 11 and 12 to move relative to each other. In this case, the contacts 11 can be fixed to the fine-hole electrical discharge machining (EDM) machine 6, and the cable 8 can be placed on a conductive part that allows communication with one side of the power supply device 2 for the EDM machine.

[0089] Alternatively, the analog current generating unit 13 can be positioned at any point along the path from one side of the power supply unit 2 for the electrical discharge machine to the other. Alternatively, a switching element other than the contact switch 13a (e.g., an NMOS transistor) can be used. Alternatively, the contact switch 13a can be omitted, and the switching action performed by the contact switch 13a can be achieved by the contact or separation of the contacts 11 and 12.

[0090] Alternatively, it can be based on analog voltage V sim Peak voltage, analog voltage V simRise time, analog current I sim Average current and analog current I sim The power supply unit 2 for the electrical discharge machine is checked for abnormalities by detecting at least one of the on-time and off-time. Furthermore, the power supply unit 2 for the electrical discharge machine can also be checked for abnormalities in frequencies, etc., by detecting other factors that can determine the abnormality of peak current, current distribution, average voltage, voltage distribution, duty cycle, frequency, etc. Alternatively, the power supply unit 2 for the electrical discharge machine can be checked for abnormalities by a device other than the NC device 20 (e.g., the arithmetic unit 18).

[0091] Alternatively, the power supply device 2 for the EDM machine can be checked for abnormalities even when there is no EDM fluid in the machining tank 3. Furthermore, the power supply device 2 can be checked for abnormalities even when at least one of the workpiece 5 and the tube electrode 7 is absent. Moreover, the contact switch 13a can be checked for malfunctions or contacts 11 and 12 can be checked for poor contact at any time before machining the workpiece 5.

[0092] This invention is not limited to the fine-hole EDM machine 6 described in the above embodiment, but can also be applied to other EDM machines. For example, this invention can also be applied to EDM forming machines. One example is shown below. Figure 7 .exist Figure 7 In the diagnostic device 1′, there are: contacts 11′ and 12′, an analog current generation unit 13, an operational amplifier 14 serving as a voltage detection unit, a current detection unit 15, analog-to-digital converters (ADCs) 16 and 17, an arithmetic unit 18 and 19, and an NC device 20. The worktable 4′ is fixed to the top of the machine base 41, and the workpiece 5′ is mounted on the worktable 4′. The worktable 4′ is surrounded by a machining groove 3′ that can be raised and lowered in the a′ or b′ direction. When machining the workpiece using the EDM machine 6′, the machining groove 3′ rises to supply EDM fluid. In the machine base 41, an XY slider 42 movable in the X and Y axes is provided. At the front end of the XY slider 42, a spindle assembly 32′ movable in the Z-axis direction is provided. At the lower end of the spindle assembly 32′, an electrode 7′ is mounted via an electrode holder 31′. By connecting one side of the power supply unit 2 for the electrical discharge machine to the power supply base 35' of the electrode holder 31' and the other side of the power supply unit 2 for the electrical discharge machine to the conductive part 25' of the worktable 4', a pulse voltage is applied between the electrodes, and the workpiece 5' and the electrode 7' are moved relative to each other in the electrical discharge fluid, thereby performing the processing discharge by the electrical discharge forming machine 6'.

[0093] and Figure 1The contacts 11 and 12 in the illustrated embodiment are equivalent to Figure 7 In the illustrated embodiment, contacts 11′ and 12′ are respectively disposed on the upper part of the electrode holder 31′ and the column 21′ erected on the base 41. Contact 12′ is fixed to the column 21′ via the insulating part 22′. Contact 11′ is connected to one side of the power supply unit 2 for the EDM machine via the power supply base 35′. Contact 12′ is connected to the conductive part 25′ of the worktable 4′ via the simulated current generating part 13, thereby being connected to the other side of the power supply unit 2 for the EDM machine.

[0094] Before the machining tank 3' rises and is supplied with EDM fluid during the pre-EDM stage using the EDM forming machine 6', the contacts 11' and 12' are brought into contact by the relative movement of the contacts 11' and 12' along the X, Y, and Z axes. This allows for the utilization of the... Figure 1 The same method described in the illustrated embodiment is used to diagnose the power supply unit 2 for the electrical discharge machine. Furthermore, to check for malfunctions in the contact switch 13a of the analog current generation unit 13 and for poor contact in the contacts 11' and 12', the same method used for... Figure 1 The method described in the embodiment shown is the same as that described above. The explanation of the structure and function of the analog current generation unit 13, operational amplifier 14, shunt resistor 15a, current readout amplifier 15b, ADC 16, 17, arithmetic unit 18, 19, NC device 20, pulse generation circuit 9, and power supply unit 2 for EDM machine is the same as that for the… Figure 1 The embodiments shown are identical to those described, therefore, their descriptions are omitted.

[0095] Explanation of reference numerals in the attached figures

[0096] 1.1' Diagnostic Device

[0097] 2 Power supply unit for electrical discharge machining (EDM) machine

[0098] 3, 3' machining groove

[0099] 4, 4' workbench

[0100] 5.5′ workpiece

[0101] 6-hole EDM machine

[0102] 6′ Electrical Discharge Machining Machine

[0103] 7-tube electrode

[0104] 7′ electrode

[0105] 9-pulse generator circuit

[0106] Contacts 11, 12, 11', and 12'

[0107] 13 Analog Current Generation Unit

[0108] 14 operational amplifier

[0109] 15 Current Detection Section

[0110] 18 and 19 Computational Units

[0111] 20NC device

[0112] 25 conductive parts

[0113] 31, 31' Electrode Holder

[0114] 32, 32' spindle assembly

[0115] 35, 35′ power supply socket

Claims

1. A diagnostic device for a power supply unit for an electrical discharge machining (EDM) machine, wherein, in order to perform EDM on a workpiece using an EDM machine, the power supply unit applies a pulsed voltage between electrodes consisting of a workpiece and electrodes facing each other with a predetermined gap, wherein... The diagnostic device is equipped with: The first contact is capable of being connected to one side of the power supply device for the electrical discharge machine via the conductive part of the electrical discharge machine. The second contact is connected to the other side of the power supply device for the electrical discharge machine via a conductive part of the worktable on which the workpiece is disposed, and can contact or separate from the first contact. The simulated current generating unit is connected in series with the power supply device for the electrical discharge machine when the first contact and the second contact are in contact. Based on the applied voltage of the power supply device for the electrical discharge machine, it generates a simulated current that simulates the current generated due to the insulation failure between the electrodes. as well as The determination unit detects the simulated current and determines whether there is any abnormality in the power supply device for the electrical discharge machine based on the simulated current.

2. The diagnostic device for the power supply unit of an EDM machine as described in claim 1, wherein, The determination unit determines whether there is any abnormality in the power supply device for the electrical discharge machine based on at least one of the on-time and off-time of the simulated current and the average current of the simulated current.

3. The diagnostic device for the power supply unit of an EDM machine as described in claim 1, wherein, Before generating the simulated current, the determination unit detects a simulated voltage generated by the power supply device for the electrical discharge machine before the insulation between the electrodes breaks down, either when the first contact and the second contact are in contact or when the first contact and the second contact are not in contact. Based on the simulated voltage, the determination unit determines whether there is an abnormality in the power supply device for the electrical discharge machine.

4. The diagnostic device for the power supply unit of an EDM machine as described in claim 3, wherein, The determination unit determines whether there is an abnormality in the power supply device for the electrical discharge machine based on at least one of the peak voltage of the analog voltage and the rise time of the analog voltage.

5. The diagnostic device for the power supply unit of an EDM machine as described in claim 3, wherein, The simulated current generating unit has a resistor connected in series with the power supply device for the electrical discharge machine, and the resistor has a resistance value equivalent to the resistance value between the electrodes when the insulation failure occurs.

6. The diagnostic device for the power supply unit of an electrical discharge machining machine as described in claim 5, wherein, The analog current generating unit also has a switching element connected in series with the resistor. When generating the analog voltage, the switching element is turned on by the NC device of the EDM machine, and when generating the analog current, the switching element is turned off by the NC device of the EDM machine.

7. The diagnostic device for the power supply unit of an EDM machine as described in claim 6, wherein, The switching element is a contact switch.

8. The diagnostic device for the power supply unit of an electrical discharge machining machine as described in claim 1, wherein, The determination unit determines whether there is poor contact between the first contact and the second contact.

9. The diagnostic device for the power supply unit of an electrical discharge machining machine as described in claim 6, wherein, The determination unit determines whether the switching element has a malfunction.

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