Control device, electrodischarge machining apparatus, and control method

Abstract

A control device for controlling an electrodischarge machining unit that performs electrodischarge machining on a workpiece in a machining liquid controls the electrodischarge machining unit on the basis of a first machining condition to perform electrodischarge machining on the workpiece when the workpiece comprises an aluminum-based material and the specific resistance value of the machining liquid is greater than a threshold, and controls the electrodischarge machining unit on the basis of a second machining condition different from the first machining condition to perform electrodischarge machining on the workpiece when the workpiece comprises an aluminum-based material and the specific resistance value of the machining liquid is equal to or less than the threshold.

Description

Control device, electric discharge machine, and control method

[0001] The present disclosure relates to a control device, an electric discharge machine, and a control method.

[0002] Japanese Patent Application Laid-Open Publication No. 2010-260151 discloses a wire electric discharge machine that performs electric discharge machining on a workpiece in a machining fluid.

[0003] Recently, there has been a demand for better control devices, electrical discharge machines and control methods.

[0004] A first aspect of the present disclosure is a control device that controls an electric discharge machining unit that performs electric discharge machining on a workpiece in a machining fluid, the control device having a material determination unit that determines whether the workpiece is made of an aluminum-based material, a resistivity determination unit that determines whether the resistivity value of the machining fluid is below a threshold value, and a control unit that controls the electric discharge machining unit, and if the workpiece is made of an aluminum-based material and the resistivity value of the machining fluid is greater than the threshold value, the control unit controls the electric discharge machining unit based on first machining conditions to perform electric discharge machining on the workpiece, and if the workpiece is made of an aluminum-based material and the resistivity value of the machining fluid is below the threshold value, the control unit controls the electric discharge machining unit based on second machining conditions that are different from the first machining conditions to perform electric discharge machining on the workpiece.

[0005] A second aspect of the present disclosure is an electric discharge machine, the electric discharge machine having the control device of the first aspect.

[0006] A third aspect of the present disclosure is a control method for an electric discharge machine equipped with an electric discharge machining unit that performs electric discharge machining on a workpiece in machining fluid, the control method comprising: a material determination step of determining whether the workpiece is made of an aluminum-based material; a resistivity determination step of determining whether the resistivity value of the machining fluid is equal to or less than a threshold value; and a control step of controlling the electric discharge machining unit, wherein if the workpiece is made of an aluminum-based material and the resistivity value of the machining fluid is greater than the threshold value, the control step controls the electric discharge machining unit based on first machining conditions to perform electric discharge machining on the workpiece, and if the workpiece is made of an aluminum-based material and the resistivity value of the machining fluid is equal to or less than the threshold value, the control step controls the electric discharge machining unit based on second machining conditions different from the first machining conditions to perform electric discharge machining on the workpiece.

[0007] FIG. 1 is a schematic diagram of an electric discharge machine. FIG. 2 is a block diagram showing the configuration of a control device. FIG. 3 shows a table of first machining conditions and a table of second machining conditions. FIG. 4 is a schematic diagram of a machining information input screen displayed on a display unit. FIG. 5 is a flowchart showing the flow of electric discharge machining processing performed by the control device on a workpiece made of an aluminum-based material. FIG. 6 is a block diagram showing the configuration of the control device. FIG. 7 is a flowchart showing the flow of electric discharge machining processing performed by the control device on a workpiece made of an aluminum-based material. FIG. 8 is a block diagram showing the configuration of the control device. FIG. 9 is a schematic diagram of a search screen displayed on a display unit.

[0008] Electrical discharge machines perform electrical discharge machining on a workpiece in machining fluid. The machining fluid used in electrical discharge machining contains sludge that is generated during the machining process. The machining fluid containing the sludge is filtered through a filter to remove the sludge. The machining fluid from which the sludge has been removed is reused in electrical discharge machining. As the filter filters the machining fluid, sludge adheres to the filter.

[0009] When the filter becomes clogged with sludge, the resistance acting on the machining fluid passing through the filter increases. When this resistance increases, the user must replace the filter. After use, filters are usually discarded without being reused. To reduce the frequency of filter replacement and the amount of filter waste, it is necessary to extend the filter's lifespan.

[0010] When an electric discharge machine performs electric discharge machining on a workpiece made of an aluminum-based material, the filter life is shorter than when the electric discharge machine performs electric discharge machining on a workpiece made of an iron-based material. When electric discharge machining is performed on a workpiece made of an aluminum-based material, aluminum hydroxide is produced in the machining fluid. Aluminum hydroxide has a relatively high viscosity, and it is thought that adhesion of the aluminum hydroxide to the filter shortens the filter life. The filter life when electric discharge machining is performed on a workpiece made of an aluminum-based material is 10% to 25% of the filter life when electric discharge machining is performed on a workpiece made of an iron-based material.

[0011] Adding a chemical that imparts ions to the machining fluid can suppress the generation of aluminum hydroxide in the machining fluid. Therefore, adding this chemical to the machining fluid can extend the life of the filter. However, adding this chemical to the machining fluid reduces the specific resistance of the machining fluid.

[0012] The lower the resistivity of the machining fluid in an electric discharge machine, the more likely it is that an electric discharge will occur between the electrode and the workpiece. Therefore, when the resistivity of the machining fluid is relatively low, an electric discharge will occur before sufficient electrical energy is stored between the electrodes, resulting in less workpiece removal. As a result, the discharge gap, which is the distance between the electrode and the workpiece after the discharge, becomes smaller. When the discharge gap becomes smaller, it becomes more difficult for an electric discharge to occur stably between the electrodes, resulting in a decrease in the machining quality of the workpiece surface and a decrease in the machining accuracy of the workpiece.

[0013] The technology disclosed herein aims to provide a control device, an electric discharge machine, and a control method that can ensure the machining quality and machining accuracy of a workpiece even when the resistivity of the machining fluid is relatively low.

[0014] 1 is a schematic diagram of an electric discharge machine 10. The electric discharge machine 10 has a control device 11, an electric discharge machining unit 12, and a machining fluid treatment unit 14. The electric discharge machine 10 is, for example, a wire electric discharge machine, but is not limited to this.

[0015] The control device 11 controls the electric discharge machining unit 12 to perform electric discharge machining on the workpiece. The electric discharge machining unit 12 has a machining tank 16. The electric discharge machining unit 12 performs electric discharge machining on the workpiece in a machining fluid stored in the machining tank 16.

[0016] The machining fluid treatment section 14 has a dirty fluid tank 18 , a clean fluid tank 20 , an ion exchange section 22 and a resistivity measurement section 23 .

[0017] The machining fluid used in the electric discharge machining is discharged from the machining tank 16 to the waste fluid tank 18 through a drainage path 24. The machining fluid discharged from the machining tank 16 contains sludge generated during the electric discharge machining.

[0018] The machining fluid stored in the waste fluid tank 18 is sent to the clean fluid tank 20 through a filtration path 26. A first pump 28 and a filter 30 are provided in the filtration path 26. The first pump 28 sends the machining fluid from the waste fluid tank 18 to the clean fluid tank 20. The filter 30 filters the machining fluid sent from the waste fluid tank 18 to the clean fluid tank 20 and removes sludge from the machining fluid.

[0019] The machining fluid stored in the clean fluid tank 20 circulates between the clean fluid tank 20 and the ion exchange unit 22 through a circulation path 32. A second pump 34 and a valve 36 are provided in the circulation path 32. The second pump 34 circulates the machining fluid between the clean fluid tank 20 and the ion exchange unit 22. The valve 36 adjusts the amount of machining fluid circulating between the clean fluid tank 20 and the ion exchange unit 22.

[0020] The ion exchange unit 22 exchanges ions in the machining fluid. The ion exchange unit 22 includes an ion exchange resin. The ion exchange resin captures specific ions contained in the machining fluid passing through the ion exchange resin and releases other ions.

[0021] The machining fluid stored in the clean fluid tank 20 is sent to the machining tank 16 through a supply path 38 .

[0022] When the electric discharge machining unit 12 performs electric discharge machining on a workpiece made of an aluminum-based material, a chemical that imparts ions to the machining fluid is added to the machining fluid. Examples of chemicals that can be added to the machining fluid include sodium bisulfite, sodium carbonate, sodium sulfate, calcium hydroxide, sodium disulfite (sodium pyrosulfite), potassium disulfite (potassium pyrosulfite), magnesium sulfate, and magnesium sulfate heptahydrate. Adding such chemicals to the machining fluid suppresses the generation of aluminum hydroxide in the machining fluid when electric discharge machining is performed on a workpiece made of an aluminum-based material. Adding such chemicals to the machining fluid also reduces the resistivity of the machining fluid.

[0023] By adding the chemical to the machining fluid, the machining fluid contains at least one of the following cations: potassium ion, calcium ion, sodium ion, and magnesium ion. Also, by adding the chemical to the machining fluid, the machining fluid contains at least one of the following anions: sulfate ion, sulfite ion, disulfite ion, bisulfite ion, hydroxide ion, nitrate ion, and nitrite ion.

[0024] The resistivity measuring unit 23 includes, for example, a resistivity sensor that detects the resistivity of the machining fluid stored in the clean fluid tank 20.

[0025] [Configuration of the Control Device] FIG. 2 is a block diagram showing the configuration of the control device 11. The control device 11 has a calculation unit 40 and a storage unit 42. The calculation unit 40 is a processor such as a central processing unit (CPU) or a graphics processing unit (GPU). The calculation unit 40 includes a material determination unit 44, a resistivity determination unit 46, and a control unit 48. The material determination unit 44, the resistivity determination unit 46, and the control unit 48 are realized by the calculation unit 40 executing a program stored in the storage unit 42. At least a portion of the material determination unit 44, the resistivity determination unit 46, and the control unit 48 may be realized by an integrated circuit such as an application specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). At least a portion of the material determination unit 44, the resistivity determination unit 46, and the control unit 48 may be realized by an electronic circuit including discrete devices.

[0026] The storage unit 42 is configured with a volatile memory (not shown) and a non-volatile memory (not shown), which are computer-readable storage media. The volatile memory is, for example, a random access memory (RAM). The non-volatile memory is, for example, a read-only memory (ROM) or a flash memory. Data, for example, is stored in the volatile memory. Programs, tables, maps, for example, are stored in the non-volatile memory. At least a portion of the storage unit 42 may be provided in the processor, integrated circuit, etc. described above. At least a portion of the storage unit 42 may be mounted on a device connected to the electric discharge machine 10 via a network. The storage unit 42 includes a machining condition storage unit 50.

[0027] The material determination unit 44 determines whether the workpiece to be electric discharge machined by the electric discharge machining unit 12 is made of an aluminum-based material. This determination will be described in detail later. The resistivity determination unit 46 determines whether the resistivity of the machining fluid is equal to or less than a threshold value. The control unit 48 controls the electric discharge machining unit 12 based on the machining program and machining conditions to perform electric discharge machining on the workpiece.

[0028] The machining condition storage unit 50 stores first machining conditions and second machining conditions. When the workpiece is made of an aluminum-based material and the resistivity of the machining fluid is greater than a threshold value, the control unit 48 reads the first machining conditions from the machining condition storage unit 50. The control unit 48 controls the electric discharge machining unit 12 based on the read first machining conditions. When the workpiece is made of an aluminum-based material and the resistivity of the machining fluid is equal to or less than a threshold value, the control unit 48 reads second machining conditions corresponding to the resistivity of the machining fluid from the machining condition storage unit 50. The control unit 48 controls the electric discharge machining unit 12 based on the read second machining conditions. The machining condition storage unit 50 stores at least one second machining condition associated with a resistivity value.

[0029] [Regarding the first and second machining conditions] When performing electrical discharge machining on a workpiece made of an aluminum-based material, a chemical agent that suppresses the generation of aluminum hydroxide in the machining fluid is sometimes added to the machining fluid. Adding such a chemical agent to the machining fluid reduces the specific resistance of the machining fluid. Simply reducing the specific resistance of the machining fluid reduces the discharge gap, making it difficult for stable discharge to occur between the electrodes. This can result in a decrease in the machining quality of the workpiece surface and a decrease in the machining accuracy of the workpiece.

[0030] Therefore, when the workpiece is made of an aluminum-based material and the resistivity of the machining fluid is greater than the threshold value, the control device 11 of this embodiment performs electric discharge machining on the workpiece based on the first machining conditions. On the other hand, when the workpiece is made of an aluminum-based material and the resistivity of the machining fluid is equal to or less than the threshold value, the control device 11 of this embodiment performs electric discharge machining on the workpiece based on the second machining conditions. As a result, electric discharge machining is performed on the workpiece based on machining conditions that correspond to the resistivity of the machining fluid, thereby improving the machining quality and accuracy of the workpiece.

[0031] 3 shows a table of the first machining conditions and a table of the second machining conditions. In this embodiment, at least the on-time, servo voltage, and offset amount of the machining conditions are different between the first machining conditions and the second machining conditions.

[0032] The on-time is the time during which a discharge occurs between the electrodes and current flows between the electrodes. By setting the on-time to a large value, the discharge energy can be increased. As a result, the amount of workpiece removed per discharge increases, and the discharge gap becomes larger. The on-time is also called the discharge time, duration, or pulse width.

[0033] The servo voltage is a voltage that is compared with the average gap voltage to control the feed of the wire electrode relative to the table on which the workpiece is placed. Note that the feed of the wire electrode refers to the movement of the wire electrode relative to the workpiece while changing its machining position. The electric discharge machine 10 controls the feed of the wire electrode according to the deviation between the average of the fed-back gap voltage and the servo voltage. Setting the servo voltage to a large value increases the discharge gap. The servo voltage is also called the servo reference voltage.

[0034] The offset is the amount of correction of the electrode path relative to the finished surface of the workpiece. By setting the offset to a large value, the discharge gap becomes larger.

[0035] In Figure 3, circled values ​​indicate values ​​of second machining conditions that are different from the values ​​of the first machining conditions. As shown in Figure 3, the second machining conditions in the first machining run (first cut, rough machining) are set to the same as the first machining conditions in the first machining run. The on-time and servo voltage of the second machining conditions in the second machining run (second cut, semi-finishing machining) are set to values ​​greater than the on-time and servo voltage of the first machining conditions in the second machining run. The servo voltage and offset amount of the second machining conditions in the third machining run (third cut, finishing machining) are set to values ​​greater than the servo voltage and offset amount of the first machining conditions in the third machining run.

[0036] This ensures a sufficient discharge gap for wire electrical discharge machining even when the resistivity of the machining fluid is equal to or less than the threshold value, thereby enabling stable generation of electrical discharge between the electrodes and improving the machining quality and accuracy of the workpiece.

[0037] The first and second processing conditions shown in FIG. 3 are merely examples, and the processing conditions are not limited to the first and second processing conditions shown in FIG.

[0038] The second machining conditions in the first machining may be different from the first machining conditions in the first machining. The offset amount of the second machining conditions in the second machining may also be set to a value larger than the offset amount of the first machining conditions in the second machining. The on-time of the second machining conditions in the third machining may also be set to a value larger than the on-time of the first machining conditions in the third machining. Furthermore, items other than the on-time, servo voltage, and offset amount may be different between the first machining conditions and the second machining conditions.

[0039] [Determination of Workpiece Material] As described above, the material determination unit 44 determines whether the workpiece to be electric discharge machined by the electric discharge machining unit 12 is made of an aluminum-based material. The material determination unit 44 determines whether the workpiece is made of an aluminum-based material based on the workpiece material input by the user using the input unit 54 (FIG. 2).

[0040] 4 is a schematic diagram of a machining information input screen 58 displayed on the display unit 56. For example, the display unit 56 may be a display provided in the electric discharge machine 10. The display unit 56 may be a display connected to a computer that performs design, creation of a machining program, simulation of electric discharge machining, etc.

[0041] The machining information input screen 58 is a screen for the user to input information about the electric discharge machining to be performed, such as the diameter of the wire electrode, the material of the wire electrode, the material of the workpiece, the thickness of the workpiece, and the height of the bottom surface of the workpiece.

[0042] 4, the processing information input screen 58 has a material input section 60. The user uses the input section 54 to input the material (material) of the workpiece into the material input section 60. The material determination section 44 determines whether the material of the workpiece is made of an aluminum-based material based on the material (material) of the workpiece input into the material input section 60.

[0043] The input unit 54 may be, for example, a keyboard, a mouse, a touch panel, or a voice recognition device.

[0044] [Electrical Discharge Machining Process] FIG. 5 is a flowchart showing the flow of electrical discharge machining process performed by the control device 11 on a workpiece made of an aluminum-based material.

[0045] In step S1, the material determination unit 44 determines whether the workpiece is made of an aluminum-based material. If the workpiece is made of an aluminum-based material, the process proceeds to step S2. If the workpiece is made of a material other than an aluminum-based material, the electric discharge machining process is terminated.

[0046] In step S2, the resistivity determination unit 46 determines whether the resistivity of the machining fluid is equal to or less than a threshold value. If the resistivity is equal to or less than the threshold value, the process proceeds to step S3. If the resistivity is greater than the threshold value, the process proceeds to step S5.

[0047] In step S3, the control unit 48 reads the second machining conditions corresponding to the resistivity of the machining fluid from the machining condition storage unit 50. Thereafter, the process proceeds to step S4.

[0048] In step S4, the control unit 48 controls the electric discharge machining unit 12 based on the read second machining conditions to perform electric discharge machining on the workpiece, and then ends the electric discharge machining process.

[0049] In step S5, the control unit 48 reads the first machining conditions from the machining condition storage unit 50. After that, the process proceeds to step S6.

[0050] In step S6, the control unit 48 controls the electric discharge machining unit 12 based on the read first machining conditions to perform electric discharge machining on the workpiece, and then ends the electric discharge machining process.

[0051] Second Embodiment In this embodiment, a part of the configuration of the control device 11 is different from the control device 11 of the first embodiment. Fig. 6 is a block diagram showing the configuration of the control device 11. The calculation unit 40 of the control device 11 of this embodiment further includes a machining condition calculation unit 62 in addition to the material determination unit 44, the resistivity determination unit 46, and the control unit 48. The storage unit 42 of the control device 11 of this embodiment further includes a correction coefficient storage unit 64 in addition to the machining condition storage unit 50.

[0052] The processing condition storage unit 50 stores the first processing conditions. The correction coefficient storage unit 64 stores the correction coefficients. The correction coefficient storage unit 64 stores at least one of the correction coefficients associated with the resistivity values.

[0053] The machining condition calculation unit 62 calculates second machining conditions based on the first machining conditions and the correction coefficient. When the workpiece is made of an aluminum-based material and the resistivity of the machining fluid is equal to or less than a threshold, the machining condition calculation unit 62 reads the first machining conditions from the machining condition storage unit 50 and reads a correction coefficient corresponding to the resistivity of the machining fluid from the correction coefficient storage unit 64. The machining condition calculation unit 62 multiplies the read first machining conditions by the read correction coefficient to calculate the second machining conditions.

[0054] When the workpiece is made of an aluminum-based material and the resistivity of the machining fluid is greater than the threshold value, the control unit 48 reads the first machining conditions from the machining condition storage unit 50. The control unit 48 controls the electric discharge machining unit 12 based on the read first machining conditions.

[0055] When the workpiece is made of an aluminum-based material and the resistivity of the machining fluid is equal to or less than the threshold value, the control unit 48 controls the electric discharge machining unit 12 based on the calculated second machining conditions.

[0056] [Electrical Discharge Machining Process] FIG. 7 is a flowchart showing the flow of electrical discharge machining process performed by the control device 11 on a workpiece made of an aluminum-based material.

[0057] In step S11, the material determination unit 44 determines whether the workpiece is made of an aluminum-based material. If the workpiece is made of an aluminum-based material, the process proceeds to step S12. If the workpiece is made of a material other than an aluminum-based material, the electric discharge machining process is terminated.

[0058] In step S12, the resistivity determination unit 46 determines whether the resistivity of the machining fluid is equal to or less than a threshold value. If the resistivity is equal to or less than the threshold value, the process proceeds to step S13. If the resistivity is greater than the threshold value, the process proceeds to step S16.

[0059] In step S13, the machining condition calculation unit 62 reads the first machining conditions from the machining condition storage unit 50. The machining condition calculation unit 62 also reads the correction coefficient corresponding to the resistivity of the machining fluid from the correction coefficient storage unit 64. Then, the process proceeds to step S14.

[0060] In step S14, the machining condition calculation unit 62 calculates second machining conditions based on the first machining conditions and the correction coefficients that have been read in. Then, the process proceeds to step S15.

[0061] In step S15, the control unit 48 controls the electric discharge machining unit 12 based on the calculated second machining conditions to perform electric discharge machining on the workpiece, and then ends the electric discharge machining process.

[0062] In step S16, the control unit 48 reads the first machining conditions from the machining condition storage unit 50. After that, the process proceeds to step S17.

[0063] In step S17, the control unit 48 controls the electric discharge machining unit 12 based on the read first machining conditions to perform electric discharge machining on the workpiece, and then ends the electric discharge machining process.

[0064] Third Embodiment In this embodiment, the determination method in the material determination unit 44 is different from the determination method in the material determination unit 44 of the first embodiment. The material determination unit 44 of this embodiment determines whether or not the workpiece is made of an aluminum-based material based on a machining program executed in the control unit 48.

[0065] The file containing the machining program can contain comments. The comments may include information about the material of the workpiece. The control unit 48 executes the machining program and controls the electric discharge machining unit 12 based on the machining program.

[0066] If a comment indicating that the workpiece is made of an aluminum-based material is written in the file of the machining program executed by the control unit 48, the material determination unit 44 determines that the workpiece is made of an aluminum-based material. If a comment indicating that the workpiece is made of a material other than an aluminum-based material is written in the file of the machining program executed by the control unit 48, the material determination unit 44 determines that the workpiece is made of a material other than an aluminum-based material.

[0067] The material determination unit 44 may determine whether the workpiece is made of an aluminum-based material based on a macro executed in the control unit 48.

[0068] Comments can also be written in the file containing the macro. This file may contain comments about the material of the workpiece. The macro is executed in the control unit 48, and the control unit 48 performs processing based on the macro.

[0069] If a comment indicating that the workpiece is made of an aluminum-based material is written in the file of the macro executed by the control unit 48, the material determination unit 44 determines that the workpiece is made of an aluminum-based material. If a comment indicating that the workpiece is made of a material other than an aluminum-based material is written in the file of the macro executed by the control unit 48, the material determination unit 44 determines that the workpiece is made of a material other than an aluminum-based material.

[0070] Fourth Embodiment In this embodiment, the determination method in the material determination unit 44 is different from the determination method in the material determination unit 44 in the first embodiment. The material determination unit 44 in this embodiment determines whether or not the workpiece is made of an aluminum-based material based on search conditions set when searching for processing conditions.

[0071] In this embodiment, the configuration of the control device 11 is partially different from that of the control device 11 of the first embodiment. Fig. 8 is a block diagram showing the configuration of the control device 11. The calculation unit 40 of the control device 11 of this embodiment further includes a search unit 66 in addition to a material determination unit 44, a resistivity value determination unit 46, and a control unit 48.

[0072] The machining condition storage unit 50 stores a plurality of machining conditions in advance, and the search unit 66 searches for machining conditions that correspond to the search conditions.

[0073] 9 is a schematic diagram of a search screen 68 displayed on the display unit 56. The search screen 68 is a screen on which a user inputs search conditions and displays search results based on the input search conditions. As shown in FIG. 9, the search screen 68 has a material input section 70, a search result display section 72, and a processing condition display section 74.

[0074] The user uses the input unit 54 (FIG. 8) to input the workpiece material (material) as a search condition in the material input unit 70. Search conditions for items other than the workpiece material (material) may also be set. A list of machining conditions corresponding to the search conditions is displayed in the search result display unit 72. Details of the machining conditions selected by the user from the list of machining conditions displayed in the search result display unit 72 are displayed in the machining condition display unit 74.

[0075] The material determination unit 44 determines whether or not the workpiece is made of an aluminum-based material based on the material of the workpiece set as a search condition.

[0076] When an aluminum-based material is set as a search condition for the workpiece material, the material determination unit 44 determines that the workpiece is made of an aluminum-based material. When a material other than an aluminum-based material is set as a search condition for the workpiece material, the material determination unit 44 determines that the workpiece is made of a material other than an aluminum-based material.

[0077] The machining conditions displayed in the search result display section 72 may be the first machining conditions or the second machining conditions. When an aluminum-based material is set as the search condition for the workpiece material (material) and a resistivity value greater than the threshold value is set as the search condition for the machining fluid resistivity value, the first machining conditions are displayed in the search result display section 72. When an aluminum-based material is set as the search condition for the workpiece material (material) and a resistivity value equal to or less than the threshold value is set as the search condition for the machining fluid resistivity value, the second machining conditions are displayed in the search result display section 72.

[0078] Fifth Embodiment In this embodiment, the determination method in the material determination unit 44 is different from the determination method in the material determination unit 44 in the first embodiment. In this embodiment, the material determination unit 44 determines whether or not the workpiece is made of an aluminum-based material based on the processing conditions set in the control unit 48.

[0079] As shown in the search result display section 72 and the machining condition display section 74 in Fig. 9, each machining condition is assigned a unique number. The machining conditions may correspond to the material of the workpiece that is to be machined using electrical discharge machining based on those machining conditions. In that case, it may be possible to determine whether the workpiece is made of an aluminum-based material based on the machining conditions set in the control section 48.

[0080] As shown in Fig. 9, comments can be written in the file that describes the machining conditions. Information about the material of the workpiece may be written as a comment.

[0081] If a comment indicating that the workpiece is made of an aluminum-based material is written in the file of processing conditions set in the control unit 48, the material determination unit 44 determines that the workpiece is made of an aluminum-based material. If a comment indicating that the workpiece is made of a material other than an aluminum-based material is written in the file of processing conditions set in the control unit 48, the material determination unit 44 determines that the workpiece is made of a material other than an aluminum-based material.

[0082] The machining conditions set in the control unit 48 may be either the first machining conditions or the second machining conditions. When the workpiece is made of an aluminum-based material and the resistivity of the machining fluid is greater than a threshold value, if the machining conditions already set in the control unit 48 are different from the first machining conditions, the first machining conditions may be newly set in the control unit 48. When the workpiece is made of an aluminum-based material and the resistivity of the machining fluid is equal to or less than a threshold value, if the machining conditions already set in the control unit 48 are different from the second machining conditions, the second machining conditions may be newly set in the control unit 48.

[0083] According to the control device 11, electric discharge machine 10, and control method of the present disclosure, even when the resistivity value of the machining fluid is relatively low, it is possible to ensure the machining quality and machining accuracy of the workpiece.

[0084] The following additional notes are further disclosed regarding the above embodiment.

[0085] (Supplementary Note 1) A control device (11) controls an electric discharge machining unit (12) that performs electric discharge machining on a workpiece in machining fluid, the control device having a material determination unit (44) that determines whether the workpiece is made of an aluminum-based material, a resistivity determination unit (46) that determines whether the resistivity value of the machining fluid is equal to or less than a threshold value, and a control unit (48) that controls the electric discharge machining unit, and if the workpiece is made of an aluminum-based material and the resistivity value of the machining fluid is greater than the threshold value, the control unit controls the electric discharge machining unit based on first machining conditions to perform electric discharge machining on the workpiece, and if the workpiece is made of an aluminum-based material and the resistivity value of the machining fluid is equal to or less than the threshold value, the control unit controls the electric discharge machining unit based on second machining conditions different from the first machining conditions to perform electric discharge machining on the workpiece.

[0086] (Supplementary Note 2) In the control device described in Supplementary Note 1, the first machining condition and the second machining condition may include at least one of a servo voltage, a voltage pulse duration which is the duration of a voltage pulse, and an electrode offset amount which is an offset amount of an electrode, and the servo voltage under the second machining condition may be greater than the servo voltage under the first machining condition, the voltage pulse duration under the second machining condition may be longer than the voltage pulse duration under the first machining condition, and the electrode offset amount under the second machining condition may be greater than the electrode offset amount under the first machining condition.

[0087] (Appendix 3) In the control device described in Appendix 1 or 2, the control device may further have a machining condition storage unit (50) that stores the second machining conditions, and the control unit may control the electric discharge machining unit based on the second machining conditions stored in the machining condition storage unit to perform electric discharge machining on the workpiece.

[0088] (Appendix 4) In the control device described in Appendix 3, the machining condition memory unit may store at least one of the second machining conditions associated with the resistivity value of the machining fluid, and the control unit may control the electric discharge machining unit based on the second machining condition corresponding to the resistivity value of the machining fluid to perform electric discharge machining on the workpiece.

[0089] (Supplementary Note 5) The control device described in Supplementary Note 1 or 2 may further include a correction coefficient storage unit (64) that stores a correction coefficient for correcting the first machining condition, and a machining condition calculation unit (62) that calculates the second machining condition based on the first machining condition and the correction coefficient, and the control unit may control the electric discharge machining unit based on the second machining condition calculated by the machining condition calculation unit to perform electric discharge machining on the workpiece.

[0090] (Appendix 6) In the control device described in Appendix 5, the correction coefficient memory unit may store at least one correction coefficient associated with the resistivity value of the machining fluid, and the machining condition calculation unit may calculate the second machining condition based on the first machining condition and the correction coefficient corresponding to the resistivity value of the machining fluid.

[0091] (Supplementary Note 7) In the control device described in any one of Supplementary Notes 1 to 6, the material determination unit may determine whether the workpiece is made of the aluminum-based material based on the material of the workpiece input by a user or based on set processing conditions.

[0092] (Appendix 8) In the control device described in any one of Appendices 1 to 6, the material determination unit may determine whether the workpiece is made of the aluminum-based material based on a machining program executed in the control device or a macro executed in the control device.

[0093] (Supplementary Note 9) The control device according to any one of Supplementary Notes 1 to 6 may further include a search unit (66) that searches for machining conditions according to search conditions, and the material determination unit may determine whether the workpiece is made of the aluminum-based material based on the search conditions.

[0094] (Supplementary Note 10) The electric discharge machine (10) has the control device according to any one of Supplementary Notes 1 to 9.

[0095] (Supplementary Note 11) A control method for an electric discharge machine equipped with an electric discharge machining unit that performs electric discharge machining on a workpiece in machining fluid, the method comprising: a material determination step of determining whether the workpiece is made of an aluminum-based material; a resistivity determination step of determining whether the resistivity value of the machining fluid is equal to or less than a threshold value; and a control step of controlling the electric discharge machining unit; if the workpiece is made of an aluminum-based material and the resistivity value of the machining fluid is greater than the threshold value, the control step controls the electric discharge machining unit based on first machining conditions to perform electric discharge machining on the workpiece; and if the workpiece is made of an aluminum-based material and the resistivity value of the machining fluid is equal to or less than the threshold value, the control step controls the electric discharge machining unit based on second machining conditions different from the first machining conditions to perform electric discharge machining on the workpiece.

[0096] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0097] REFERENCE SIGNS LIST 10... Electric discharge machine 11... Control device 12... Electric discharge machining section 44... Material determination section 46... Resistivity value determination section 48... Control section 50... Machining condition storage section 62... Machining condition calculation section 64... Correction coefficient storage section 66... ​​Search section

Claims

1. A control device for controlling an electric discharge machining unit that performs electric discharge machining on a workpiece in a machining fluid, the control device having a material determination unit that determines whether the workpiece is made of an aluminum-based material; a resistivity determination unit that determines whether the resistivity value of the machining fluid is below a threshold value; and a control unit that controls the electric discharge machining unit, wherein if the workpiece is made of an aluminum-based material and the resistivity value of the machining fluid is greater than the threshold value, the control unit controls the electric discharge machining unit based on first machining conditions to perform electric discharge machining on the workpiece, and if the workpiece is made of an aluminum-based material and the resistivity value of the machining fluid is below the threshold value, the control unit controls the electric discharge machining unit based on second machining conditions different from the first machining conditions to perform electric discharge machining on the workpiece.

2. A control device as described in claim 1, wherein the first machining condition and the second machining condition include at least one of a servo voltage, a voltage pulse duration which is the duration of a voltage pulse, and an electrode offset amount which is an offset amount of an electrode, the servo voltage in the second machining condition is greater than the servo voltage in the first machining condition, the voltage pulse duration in the second machining condition is longer than the voltage pulse duration in the first machining condition, and the electrode offset amount in the second machining condition is greater than the electrode offset amount in the first machining condition.

3. A control device as claimed in claim 1 or 2, further comprising a machining condition memory unit for storing the second machining conditions, and wherein the control unit controls the electric discharge machining unit based on the second machining conditions stored in the machining condition memory unit to perform electric discharge machining on the workpiece.

4. A control device as described in claim 3, wherein the machining condition memory unit stores at least one of the second machining conditions associated with the resistivity value of the machining fluid, and the control unit controls the electric discharge machining unit based on the second machining condition corresponding to the resistivity value of the machining fluid to perform electric discharge machining on the workpiece.

5. A control device as claimed in claim 1 or 2, further comprising: a correction coefficient memory unit which stores a correction coefficient for correcting the first machining conditions; and a machining condition calculation unit which calculates the second machining conditions based on the first machining conditions and the correction coefficient, wherein the control unit controls the electric discharge machining unit based on the second machining conditions calculated by the machining condition calculation unit to perform electric discharge machining on the workpiece.

6. A control device as described in claim 5, wherein the correction coefficient memory unit stores at least one correction coefficient associated with the resistivity value of the machining fluid, and the machining condition calculation unit calculates the second machining condition based on the first machining condition and the correction coefficient corresponding to the resistivity value of the machining fluid.

7. A control device according to any one of claims 1 to 6, wherein the material determination unit determines whether or not the workpiece is made of the aluminum-based material based on the material of the workpiece input by a user or based on set processing conditions.

8. A control device according to any one of claims 1 to 6, wherein the material determination unit determines whether or not the workpiece is made of the aluminum-based material based on a machining program executed in the control device or a macro executed in the control device.

9. A control device according to any one of claims 1 to 6, further comprising a search unit that searches for machining conditions according to search conditions, and the material determination unit determines whether or not the workpiece is made of the aluminum-based material based on the search conditions.

10. An electric discharge machine having a control device according to any one of claims 1 to 9.

11. A control method for an electric discharge machine equipped with an electric discharge machining unit which performs electric discharge machining on a workpiece in machining fluid, comprising: a material determination step of determining whether the workpiece is made of an aluminum-based material; a resistivity determination step of determining whether the resistivity value of the machining fluid is equal to or lower than a threshold value; and a control step of controlling the electric discharge machining unit, wherein if the workpiece is made of an aluminum-based material and the resistivity value of the machining fluid is greater than the threshold value, the control step controls the electric discharge machining unit based on first machining conditions to perform electric discharge machining on the workpiece; and if the workpiece is made of an aluminum-based material and the resistivity value of the machining fluid is equal to or lower than the threshold value, the control step controls the electric discharge machining unit based on second machining conditions different from the first machining conditions to perform electric discharge machining on the workpiece.

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