Electrical Discharge Machining Machine

Abstract

An electrical discharge machine (10) comprises a dirty water tank (14), a fresh water tank (16), a first pipeline (20), and a sludge filter (26). The sludge filter (26) is a porous material having pores through which fresh water passes, the fresh water being pumped up from the fresh water tank (16) and supplied from the first pipeline (20), which guides the fresh water. Machining waste is captured in the pores of the porous material.

Description

[[Technical Field]]

[0001] The present invention relates to an electric discharge machine. [[Background Art]]

[0002] An electric discharge machine machines a workpiece arranged in a machining fluid by electric discharge. Through this machining, metal from the workpiece and the like forms ions in the machining fluid. Generally, an ion exchange resin is used to reduce the metal ion concentration in the machining fluid.

[0003] Japanese Unexamined Patent Publication No. 2013-132735 discloses maintaining the specific resistance of a machining fluid at a level higher than a predetermined value using an ion exchange resin to reduce the ion concentration in the machining fluid. [[Summary of the Invention]]

[0004] However, ion exchange resins have a service life, and replacement of the ion exchange resin is required approximately every 300 hours. If the ion exchange resin is not replaced, machining accuracy becomes unstable, which tends to increase running costs for maintaining machining accuracy. Therefore, efficiently improving the specific resistance of machining fluid has been an issue.

[0005] An object of the present invention is to solve the above-described problem.

[0006] An aspect of the present invention is an electric discharge machine that machines a workpiece arranged in a machining fluid by electric discharge, comprising: a sewage tank that stores sewage that is the machining fluid containing machining swarf generated by machining the workpiece; a clean water tank that stores clean water that is the machining fluid from which the machining swarf has been removed from the sewage; a first pipe line that guides the clean water pumped from the clean water tank; and a sludge filter which is a porous body having pores through which the clean water supplied from the first pipe line passes, the machining swarf being trapped in the pores.

[0007] According to the above embodiment, the resistivity of the clean water from which processing debris has been removed can be increased by intentionally passing it through pores that have trapped the processing debris. Therefore, the resistivity of the clean water can be improved without using commonly used ion exchange resins. As a result, the resistivity of the processing fluid can be efficiently improved.

[0008] Furthermore, the reciprocal of resistivity [Ωm] is the conductivity [S / m], and there is a correlation between resistivity [Ωm] and conductivity [S / m]. Therefore, resistivity [Ωm] can be substituted for conductivity [S / m]. When resistivity [Ωm] is substituted for conductivity [S / m], the relationship between the values ​​is reversed. For example, "increasing resistivity [Ωm]" is synonymous with "decreasing conductivity [S / m]". [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram showing the configuration of an electrical discharge machining machine according to an embodiment. [Figure 2] Figure 2 is a schematic diagram showing the configuration of an electrical discharge machining machine according to Modification 1. [Figure 3] Figure 3 is a schematic diagram showing the configuration of the electrical discharge machining machine according to Modification 2. [Figure 4] Figure 4 is a schematic diagram showing the configuration of an electrical discharge machining machine according to Modification 3. [Modes for carrying out the invention]

[0010] [Embodiment] Figure 1 is a schematic diagram showing the configuration of an electrical discharge machining (EDM) machine 10 according to an embodiment. The EDM machine 10 processes a workpiece placed in a machining fluid by electrical discharge. The EDM machine 10 may be a wire EDM machine or a die-sinking EDM machine. A wire EDM machine generates a discharge between the wire electrode and the workpiece. A die-sinking EDM machine generates a discharge between the die-sinking electrode and the workpiece.

[0011] The processing fluid is a liquid used to process the workpiece. The processing fluid may be water. The workpiece is a metal such as an iron-based material or cemented carbide, an aluminum-based material, a copper alloy-based material, a nickel-based material, or a titanium-based material. The electrodes (wire electrodes or die-sinking electrodes) of the electrical discharge machining machine 10 are metals such as tungsten-based, copper alloy-based, brass-based, titanium-based, brass-based with a zinc coating, iron-based, molybdenum-based, or carbon-based materials used as core materials for brass-based materials. Note that carbon-based electrodes are only used when the electrical discharge machining machine 10 is a die-sinking electrical discharge machining machine.

[0012] The electrical discharge machining machine 10 includes a wastewater tank 14, a clean water tank 16, a first pump 18, a first pipeline 20, a second pump 22, a second pipeline 24, a sludge filter 26, an on-off valve 28, a resistivity meter 30, and a control device 32.

[0013] The wastewater tank 14 is a tank for storing wastewater. The wastewater is a processing fluid containing processing scraps generated by processing the workpiece. The clean water tank 16 is a tank for storing clean water. The clean water is a processing fluid from which processing scraps have been removed from the wastewater. The processing scraps contain at least one of the following: iron, aluminum, copper, zinc, cemented carbide, tungsten, molybdenum, carbon, titanium, silicon, manganese, chromium, phosphorus, sulfur, and nickel.

[0014] The first pump 18 draws up clean water from the clean water tank 16 and imparts fluidity to the clean water. The first pump 18 is installed in the first pipeline 20. The first pipeline 20 guides the clean water drawn up from the clean water tank 16. In this embodiment, the first pipeline 20 guides the clean water to the sludge filter 26.

[0015] The second pump 22 pumps up wastewater from the wastewater tank 14 and imparts fluidity to the wastewater. The second pump 22 is installed in the second pipeline 24. In this embodiment, the second pump 22 is installed in the second pipeline 24 between the wastewater tank 14 and the sludge filter 26. The second pipeline 24 guides the processing fluid from the wastewater tank 14 to the clean water tank 16. The second pipeline 24 has an upstream section 24-1 and a downstream section 24-2. The upstream section 24-1 guides the wastewater pumped up from the wastewater tank 14 to the sludge filter 26. The downstream section 24-2 guides the clean water flowing out of the sludge filter 26 to the clean water tank 16.

[0016] The sludge filter 26 is a porous material having pores. Processing debris generated during the processing of the workpiece is captured in the pores. The sludge filter 26 may be a porous material previously used to remove processing debris. Examples of porous materials include filter paper and filter cloth. The sludge filter 26 is housed in the filter container 34. The sludge filter 26 housed in the filter container 34 may be joined to the filter container 34.

[0017] The filter container 34 has a first fluid inlet 34-1, a second fluid inlet 34-2, and a fluid outlet 34-3. The first fluid inlet 34-1, the second fluid inlet 34-2, and the fluid outlet 34-3 communicate with the filter housing space inside the filter container 34. The filter housing space is the space in which the sludge filter 26 is housed.

[0018] The first fluid inlet 34-1 and the second fluid inlet 34-2 are located, for example, on the upper wall of the filter container 34. The first fluid inlet 34-1 and the second fluid inlet 34-2 may also be located on the side wall of the filter container 34. The fluid outlet 34-3 is located, for example, on the lower wall of the filter container 34. The fluid outlet 34-3 may also be located on the side wall of the filter container 34. The first fluid inlet 34-1 is connected to the end (downstream end) of the first pipe 20. The second fluid inlet 34-2 is connected to the end (downstream end) of the upstream section 24-1 of the second pipe 24. The fluid outlet 34-3 is connected to the end (upstream end) of the downstream section 24-2 of the second pipe 24. When the processing fluid is flowed into the clean water tank 16 by free fall from the fluid outlet 34-3, the downstream section 24-2 of the second pipe 24 may be removed.

[0019] The sludge filter 26 is supplied with either wastewater or clean water selectively. Wastewater is supplied from the wastewater tank 14 via the second pipeline 24 and the second fluid inlet 34-2 in that order. Clean water is supplied from the clean water tank 16 via the first pipeline 20 and the first fluid inlet 34-1 in that order.

[0020] When wastewater is supplied to the sludge filter 26, the sludge filter 26 removes processing debris contained in the wastewater. In this case, the processing debris is captured in the pores of the sludge filter 26. The processing fluid (clean water) from which the processing debris has been removed by the sludge filter 26 is supplied to the clean water tank 16 from the fluid outlet 34-3.

[0021] On the other hand, when clean water is supplied to the sludge filter 26, the sludge filter 26 increases the resistivity of the clean water to be greater than that of the clean water stored in the clean water tank 16. In this case, the sludge filter 26 increases the resistivity of the clean water by passing the clean water through the pores in which the processing debris is trapped.

[0022] The on-off valve 28 is provided in the first pipeline 20. The on-off valve 28 is configured to be switchable between opening and closing the first pipeline 20. When the on-off valve 28 is opened, the first pipeline 20 is opened. When the on-off valve 28 is closed, the first pipeline 20 is blocked. The opening and closing of the on-off valve 28 is performed by the control device 32.

[0023] The specific resistance meter 30 is provided in the clean water tank 16. The specific resistance meter 30 measures the specific resistance value of clean water stored in the clean water tank 16, and outputs a signal indicating the specific resistance value to the control device 32.

[0024] The control device 32 controls the first pump 18, the second pump 22, and the on-off valve 28. The control device 32 includes a processor such as a CPU or an MPU, and one or more memories such as a ROM, a RAM, and a hard disk. The control device 32 may be a numerical control device for the electrical discharge machine 10. The control device 32 may be another control device provided separately from the numerical control device of the electrical discharge machine 10. Said other control device has a processor different from the processor included in the numerical control device.

[0025] A filtration start command or a filtration end command is input to the control device 32. The filtration start command and the filtration end command are provided, for example, from an input device connected to the control device 32 in response to a user operation. The input device may be a touch panel, a keyboard and a mouse, or an operation panel.

[0026] Upon receiving the filtration start command, the control device 32 drives the second pump 22 to supply the sewage stored in the sewage tank 14 to the sludge filter 26. In this case, the control device 32 does not drive the first pump 18. Further, the control device 32 closes the on-off valve 28 to prevent sewage from flowing into the clean water tank 16.

[0027] Upon receiving the filtration end command, the control device 32 stops the second pump 22 to stop the supply of sewage to the sludge filter 26. In this case, the control device 32 compares the specific resistance value measured by the specific resistance meter 30 with a predetermined threshold value.

[0028] If the resistivity is below a predetermined threshold, the control device 32 supplies the clean water stored in the clean water tank 16 to the sludge filter 26. In this case, the control device 32 drives the first pump 18 and opens the on-off valve 28 to allow the clean water to pass through the pores of the sludge filter 26 in which processing debris is captured. As a result, the resistivity of the clean water becomes greater than the resistivity of the clean water stored in the clean water tank 16. On the other hand, if the resistivity exceeds a predetermined threshold, the control device 32 stops the first pump 18 and closes the on-off valve 28.

[0029] The inventors have found that when clean water is passed through the pores of a porous body that traps processing debris, the resistivity of the clean water increases. In this embodiment, a sludge filter 26 is provided. The sludge filter 26 is a porous body having pores through which clean water supplied from the first pipeline 20 passes. Processing debris generated by the processing of the workpiece is trapped in these pores. As a result, the resistivity of the clean water can be increased by intentionally passing the clean water, from which the processing debris has been removed, through the pores that trap the processing debris. Therefore, the resistivity of the clean water can be improved without using commonly used ion exchange resins. As a result, the resistivity of the processing fluid can be efficiently improved.

[0030] Furthermore, in this embodiment, the sludge filter 26 is provided in the second pipeline 24 that guides the processing fluid from the wastewater tank 14 to the clean water tank 16, and the first pipeline 20 guides clean water to the sludge filter 26. This allows the sludge filter 26, which increases the resistivity of the clean water, to be used as a filtration filter. As a result, the resistivity of the processing fluid can be efficiently improved.

[0031] [Variation] The above embodiment may be modified as follows.

[0032] (Variation 1) Figure 2 is a schematic diagram showing the configuration of the electrical discharge machining machine 10 according to Modification 1. In Figure 2, components equivalent to those described in the embodiment are denoted by the same reference numerals. In this modification, explanations that overlap with those in the embodiment are omitted.

[0033] In this modified example, a filtration filter 36 is newly provided in addition to the sludge filter 26. The filtration filter 36 is housed in a filter container 38. The filter container 38 has a fluid inlet 38-1 and a fluid outlet 38-2. The end (downstream end) of the upstream section 24-1 of the second pipe 24 is connected to the fluid inlet 38-1. The end (upstream end) of the downstream section 24-2 of the second pipe 24 is connected to the fluid outlet 38-2.

[0034] The filtration filter 36 is a porous material having pores. The filtration filter 36 removes processing debris contained in wastewater. Once the filtration filter 36 has been used (when wastewater has passed through the filtration filter 36 at least once), processing debris is trapped in the pores of the filtration filter 36. When a used filtration filter 36 is to be replaced with an unused filtration filter 36, it is removed from the filter container 38. In this case, the used filtration filter 36 may be used as a sludge filter 26.

[0035] In this modified example, the first pipeline 20 is formed so that clean water flows to the clean water tank 16 via the sludge filter 26. That is, the first pipeline 20 is divided into an upstream section 20-1 and a downstream section 20-2. The end of the upstream section 20-1 (downstream end) is connected to the first fluid inlet 34-1 of the filter container 34. The upstream section 20-1 guides the clean water pumped up from the clean water tank 16 to the sludge filter 26. The end of the downstream section 20-2 (upstream end) is connected to the fluid outlet 34-3 of the filter container 34. The downstream section 20-2 guides the clean water flowing out of the sludge filter 26 to the clean water tank 16.

[0036] Furthermore, in this modified example, the control device 32 compares the resistivity value measured by the resistivity meter 30 with a predetermined threshold, regardless of whether or not wastewater is being supplied to the filtration filter 36. When the resistivity value falls below the predetermined threshold, the control device 32 continues to supply clean water to the sludge filter 26 until the resistivity value exceeds the threshold.

[0037] According to this modified example, even while the wastewater is being filtered by the filtration filter 36, the clean water stored in the clean water tank 16 can be passed through the pores of the sludge filter 26 to improve the resistivity of the clean water.

[0038] (Modification 2) Figure 3 is a schematic diagram showing the configuration of the electrical discharge machining machine 10 according to Modification 2. In Figure 3, components equivalent to those described in the embodiment and Modification 1 are denoted by the same reference numerals. In this modification, explanations that overlap with those in the embodiment are omitted.

[0039] In this modified example, only the first pipeline 20 differs from that of Modified Example 1. In Modified Example 1, the first pipeline 20 is configured so that clean water flows to the clean water tank 16 via the sludge filter 26. On the other hand, in this modified example, the first pipeline 20 is configured so that clean water flows to the wastewater tank 14 via the sludge filter 26. That is, in this modified example, the downstream section 20-2 of the first pipeline 20 guides the clean water flowing out of the sludge filter 26 to the wastewater tank 14.

[0040] This modified version, like Modification 1, can improve the resistivity of the clean water.

[0041] (Variation 3) Figure 4 is a schematic diagram showing the configuration of the electrical discharge machining machine 10 according to Modification 3. In Figure 4, components equivalent to those described in the embodiment and Modification 1 are denoted by the same reference numerals. In this modification, explanations that overlap with those in the embodiment are omitted.

[0042] In this modified configuration, a processing tank 40 is newly provided. The processing tank 40 is a water tank that stores processing fluid for immersing the workpiece. The processing tank 40 is installed on the upper surface of the mounting base 42. In this modified configuration, the first pipeline 20 is configured so that clean water flows into the processing tank 40 via the sludge filter 26. That is, the downstream section 20-2 of the first pipeline 20 guides the clean water flowing out of the sludge filter 26 into the processing tank 40. Even in this modified configuration, the resistivity of the clean water can be improved, similar to the first modified configuration.

[0043] In this modified configuration, a third pipeline 44 is connected to the processing tank 40. The third pipeline 44 leads the processing fluid stored in the processing tank 40 to the wastewater tank 14. An on-off valve 46 is provided in the third pipeline 44. The on-off valve 46 is configured to switch between opening and closing the third pipeline 44. When the on-off valve 46 is open, the third pipeline 44 is open. When the on-off valve 46 is closed, the third pipeline 44 is closed. The opening and closing of the on-off valve 46 is performed by the control device 32.

[0044] The control device 32 opens the on-off valve 46 at a predetermined timing, such as when the processing of the workpiece is completed, and discharges the processing fluid stored in the processing tank 40 into the wastewater tank 14. In this case, the control device 32 may also open the on-off valve 28 and drive the first pump 18 to supply an amount of clean water to the processing tank 40 that is equivalent to the amount of processing fluid discharged into the wastewater tank 14. This makes it possible to suppress a significant increase in the ion concentration of the processing fluid stored in the processing tank 40, and as a result, it is possible to suppress a decrease in processing accuracy.

[0045] (Modification 4) The resistivity meter 30 may be replaced with a conductivity meter. The conductivity meter measures the conductivity of the clean water stored in the clean water tank 16 and outputs a signal indicating the conductivity to the control device 32. In this modified example, the control device 32 compares the conductivity measured by the conductivity meter with a predetermined threshold. In this modified example, if the conductivity is above the predetermined threshold, the control device 32 drives the first pump 18 and opens the on-off valve 28. This modified example is not limited to this embodiment and can be applied to any of the modified examples 1 to 3.

[0046] (Variation 5) The control device 32 may control the inverter that drives the first pump 18 to adjust the flow rate of clean water in the first pipeline 20. In this case, the on-off valve 28 may be removed. Alternatively, if the on-off valve 28 is a solenoid valve with an adjustable opening degree, the control device 32 may control the opening degree of the on-off valve 28 to adjust the flow rate of clean water in the first pipeline 20. This modification is not limited to this embodiment and can be applied to any of the modifications 1 to 3.

[0047] (Experimental variation 6) The sludge filter 26 may be provided in the fresh water tank 16. This modification is not limited to this embodiment and can be applied to any of the modifications 1 to 3.

[0048] 〔invention〕 The inventions and effects that can be understood from the above description are described below.

[0049] (1) The present invention relates to an electrical discharge machining machine (10) for machining a workpiece placed in a machining fluid by electrical discharge, comprising: a wastewater tank (14) for storing wastewater which is the machining fluid containing machining debris generated by machining the workpiece; a clean water tank (16) for storing clean water which is the machining fluid from which the machining debris has been removed from the wastewater; a first pipeline (20) for guiding the clean water pumped up from the clean water tank; and a sludge filter (26) which is a porous body having pores through which the clean water supplied from the first pipeline passes, and in which the machining debris is captured.

[0050] This allows the resistivity of the clean water, from which processing debris has been removed, to be intentionally passed through the pores that trap the processing debris, thereby increasing the resistivity of the clean water. Therefore, the resistivity of the clean water can be improved without using commonly used ion exchange resins. As a result, the resistivity of the processing fluid can be efficiently improved.

[0051] (2) The present invention relates to an electrical discharge machining machine, comprising a second pipeline (24) that guides the machining fluid from the wastewater tank to the clean water tank, and a filtration filter (36) provided in the second pipeline that removes machining debris from the wastewater, wherein the sludge filter may be separate from the filtration filter. This makes it possible to remove machining debris from the wastewater while improving the resistivity of the clean water.

[0052] (3) The present invention relates to an electrical discharge machining machine, wherein the first pipeline may be configured such that the clean water flows to the clean water tank via the sludge filter. This makes it possible to stabilize the resistivity of the clean water stored in the clean water tank.

[0053] (4) The present invention relates to an electrical discharge machining machine, wherein the first pipeline may be configured such that the clean water flows to the wastewater tank via the sludge filter. This makes it possible to stabilize the resistivity of the wastewater stored in the wastewater tank.

[0054] (5) The present invention relates to an electrical discharge machining machine, wherein the first pipeline may be configured such that the clean water flows through the sludge filter to a machining tank (40) that stores the machining fluid for immersing the workpiece. This makes it possible to stabilize the resistivity of the machining fluid stored in the machining layer. As a result, it is possible to suppress a significant increase in the ion concentration of the machining fluid and a decrease in machining accuracy.

[0055] (6) The present invention relates to an electrical discharge machining machine, comprising a second pipeline that guides the machining fluid from the wastewater tank to the clean water tank, wherein the sludge filter is provided in the second pipeline, and the first pipeline may guide the clean water to the sludge filter. This allows the sludge filter, which increases the resistivity of the clean water, to be used as a filtration filter. As a result, the resistivity of the machining fluid can be efficiently improved.

[0056] (7) The present invention relates to an electrical discharge machining machine, wherein the sludge filter may be the porous body that was used to remove the machining debris. This allows the filtration filter to be recycled as a sludge filter.

[0057] (8) The present invention relates to an electrical discharge machining machine, wherein the machining chips may contain at least one of iron, aluminum, copper, zinc, cemented carbide, tungsten, molybdenum, carbon, titanium, silicon, manganese, chromium, phosphorus, sulfur, and nickel. This makes it possible to appropriately increase the resistivity of the clean water.

[0058] (9) The present invention may also be an electrical discharge machining machine comprising a resistivity meter (30) for measuring the resistivity of the clean water, a pump (18) for drawing up the clean water from the clean water tank, and a control device (32) that controls the pump to draw up the clean water when the resistivity is below a predetermined threshold. This makes it possible to reliably suppress an increase in the ion concentration of the clean water.

[0059] Furthermore, the present invention is not limited to the disclosure described above, and can take various configurations without departing from the spirit of the invention. [Explanation of Symbols]

[0060] 10...Electrical discharge machining machine 14...Sewage tank 16…Clean water tank 18…First pump 20...First pipeline 22...Second pump 24...Second pipeline 26...Sludge filter 28, 46... On / off valves 30... Resistivity meter 32...Control device 34, 38...Filter container 36...Filtration filter 40...Processing tank

Claims

1. An electrical discharge machining machine that processes a workpiece placed in a machining fluid by electrical discharge, A wastewater tank for storing wastewater, which is the processing liquid containing processing scraps generated by the processing of the object to be processed, A clean water tank for storing the clean water which is the processing liquid from which the processing scraps have been removed from the wastewater, A first pipeline that guides the fresh water pumped up from the fresh water tank, A sludge filter having a porous body through which the clean water supplied from the first pipeline passes, and in which the processing debris is captured in the pores, Equipped with, An electrical discharge machine that passes the clean water through the pores of the porous body in which the processing chips are trapped, in order to increase the resistivity of the clean water.

2. An electrical discharge machine for machining a workpiece placed in a machining fluid by electrical discharge, A wastewater tank for storing wastewater, which is the processing liquid containing processing scraps generated by the processing of the object to be processed, A clean water tank for storing the clean water which is the processing liquid from which the processing scraps have been removed from the wastewater, A first pipeline that guides the fresh water pumped up from the fresh water tank, A sludge filter having a porous body through which the clean water supplied from the first pipeline passes, and in which the processing debris is captured in the pores, A second pipeline for guiding the processing fluid from the wastewater tank to the clean water tank, A filtration filter is provided in the second pipeline to remove the processing waste from the wastewater, Equipped with, The aforementioned sludge filter is separate from the aforementioned filtration filter in an electrical discharge machining (EDM) machine.

3. The electrical discharge machining machine according to claim 2, The first pipeline is configured such that the clean water flows to the clean water tank via the sludge filter in an electrical discharge machining machine.

4. The electrical discharge machining machine according to claim 2, The first pipeline is configured such that the clean water flows to the wastewater tank via the sludge filter in an electrical discharge machining machine.

5. The electrical discharge machining machine according to claim 2, The first pipeline is formed such that the clean water flows through the sludge filter to a processing tank that stores the processing fluid for immersing the workpiece, in an electrical discharge machine.

6. An electrical discharge machine for machining a workpiece placed in a machining fluid by electrical discharge, A wastewater tank for storing wastewater, which is the processing liquid containing processing scraps generated by the processing of the object to be processed, A clean water tank for storing the clean water which is the processing liquid from which the processing scraps have been removed from the wastewater, A first pipeline that guides the fresh water pumped up from the fresh water tank, A sludge filter having a porous body through which the clean water supplied from the first pipeline passes, and in which the processing debris is captured in the pores, The system includes a second pipeline that guides the processing fluid from the wastewater tank to the clean water tank. The sludge filter is provided in the second pipeline, The first pipeline is an electrical discharge machining machine that guides the clean water to the sludge filter.

7. An electrical discharge machine for machining a workpiece placed in a machining fluid by electrical discharge, A wastewater tank for storing wastewater, which is the processing liquid containing processing scraps generated by the processing of the object to be processed, A clean water tank for storing the clean water which is the processing liquid from which the processing scraps have been removed from the wastewater, A first pipeline that guides the fresh water pumped up from the fresh water tank, A sludge filter having a porous body through which the clean water supplied from the first pipeline passes, and in which the processing debris is captured in the pores, Equipped with, The first pipeline is configured such that the clean water pumped from the clean water tank flows to the clean water tank via the sludge filter without passing through the wastewater tank, in an electrical discharge machining machine.

8. An electrical discharge machining machine according to any one of claims 2 to 7, The sludge filter is the porous body used to remove the processing debris in an electrical discharge machine.

9. An electrical discharge machining machine according to any one of claims 1 to 7, An electrical discharge machine in which the processing scrap contains at least one of iron, aluminum, copper, zinc, cemented carbide, tungsten, molybdenum, carbon, titanium, silicon, manganese, chromium, phosphorus, sulfur, and nickel.

10. An electrical discharge machining machine according to any one of claims 1 to 7, A resistivity meter for measuring the resistivity of the aforementioned clean water, A pump that draws up the fresh water from the fresh water tank, A control device that controls the pump to pump up the clean water when the resistivity value is below a predetermined threshold, An electrical discharge machining machine equipped with the following features.

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