Electrical discharge machine

Abstract

An electric discharge machine (10) is provided with a sewage tank (14), a clear water tank (16), a first conduit (20), and a sludge filter (26). The sludge filter (26) is a porous body having pores through which the clear water supplied from the first line (20) is passed, and the first line (20) guides the clear water drawn from the clear water tank (16). Processing chips are captured in the pores of the porous body.

Description

Technical Field

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

[0002] The electric discharge machine processes the object to be processed placed in the processing fluid by electric discharge. Through this processing, the metal of the object to be processed is formed as ions in the processing fluid. Generally, ion exchange resin is used to reduce the concentration of metal ions in the processing fluid.

[0003] Japanese Patent Application Laid-Open No. 2013-132735 discloses that an ion exchange resin is used to maintain the resistivity of a machining fluid higher than a predetermined value, thereby reducing the ion concentration in the machining fluid. Summary of the invention

[0004] However, the ion exchange resin has a service life and needs to be replaced every 300 hours. If the ion exchange resin is not replaced, the machining accuracy becomes unstable, so there is a tendency for the running cost for maintaining the machining accuracy to increase. Therefore, there is a problem of effectively improving the resistivity of the machining fluid.

[0005] The object of the present invention is to solve the above-mentioned problems.

[0006] The present invention is an electric discharge machine that processes a processing object disposed in a processing fluid by electric discharge, and comprises: a sewage tank that stores sewage, which is the processing fluid containing processing chips generated by processing the processing object; a clean water tank that stores clean water, which is the processing fluid with the processing chips removed from the sewage; a first pipeline that guides the clean water drawn from the clean water tank; and a sludge filter, which is a porous body having pores for the clean water supplied from the first pipeline to pass through, and the pores capture the processing chips.

[0007] According to the above method, the resistivity of the clean water can be increased by intentionally passing the clean water from which the machining chips are removed through the pores that capture the machining chips. Therefore, the resistivity of the clean water can be improved without using the commonly used ion exchange resin. As a result, the resistivity of the machining fluid can be efficiently improved.

[0008] The reciprocal of resistivity [Ωm] is conductivity [S / m], and there is a correlation between resistivity [Ωm] and conductivity [S / m]. Therefore, resistivity [Ωm] can be replaced by conductivity [S / m]. When resistivity [Ωm] is replaced by conductivity [S / m], the magnitude relationship of the values ​​is reversed. For example, "increasing resistivity [Ωm]" is synonymous with "decreasing conductivity [S / m]". BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1It is a schematic diagram showing the structure of the electric discharge machine according to the embodiment. Figure 2 This is a schematic diagram showing the structure of an electric discharge machine according to Modification 1. Figure 3 This is a schematic diagram showing the structure of an electric discharge machine according to a second modification. Figure 4 It is a schematic diagram showing the structure of an electric discharge machine according to a third modification. DETAILED DESCRIPTION

[0010] [Implementation Method] Figure 1 1 is a schematic diagram showing the structure of an electric discharge machine 10 according to an embodiment. The electric discharge machine 10 processes a processing object placed in a processing fluid by electric discharge. The electric discharge machine 10 may be a wire electric discharge machine or a forming electric discharge machine. The wire electric discharge machine generates electric discharge between a wire electrode and a processing object. The forming electric discharge machine generates electric discharge between a forming electrode and a processing object.

[0011] The machining fluid is a liquid used for machining the machining object. The machining fluid may also be water. The machining object is a metal such as an iron material or a superhard material, an aluminum material, a copper alloy material, a nickel material, a titanium material, etc. The electrode (wire electrode or forming electrode) of the electric discharge machine 10 is a metal such as a tungsten material, a copper alloy material, a brass material, a titanium material, a brass material coated with zinc, an iron material used as a core material of a brass material, a molybdenum material, a carbon material, etc. In addition, the carbon material is limited to the case where the electric discharge machine 10 is a forming electric discharge machine.

[0012] The electrical discharge machine 10 includes a dirty water 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 sewage tank 14 is a tank for storing sewage. Sewage is a processing fluid containing machining chips generated by machining the object to be processed. The clean water tank 16 is a tank for storing clean water. Clean water is a processing fluid in which machining chips are removed from sewage. The machining chips include at least one of iron, aluminum, copper, zinc, cemented carbide, tungsten, molybdenum, carbon, titanium, silicon, manganese, chromium, phosphorus, sulfur, and nickel.

[0014] The first pump 18 draws clean water from the clean water tank 16 and imparts flow force to the clean water. The first pump 18 is disposed on a first pipeline 20. The first pipeline 20 guides the clean water drawn from the clean water tank 16. In the present embodiment, the first pipeline 20 guides the clean water to a sludge filter 26.

[0015] The second pump 22 draws sewage from the sewage tank 14 and imparts flow force to the sewage. The second pump 22 is disposed on the second pipeline 24. In the present embodiment, the second pump 22 is disposed on the second pipeline 24 between the sewage tank 14 and the sludge filter 26. The second pipeline 24 guides the machining fluid from the sewage tank 14 to the clean water tank 16. The second pipeline 24 has an upstream portion 24-1 and a downstream portion 24-2. The upstream portion 24-1 guides the sewage drawn from the sewage tank 14 to the sludge filter 26. The downstream portion 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 body having pores. Processing debris generated by processing the object to be processed is captured in the pores. The sludge filter 26 may be a porous body used to remove processing debris in the past. Examples of the porous body include filter paper, filter cloth, etc. The sludge filter 26 is accommodated in the filter container 34. The sludge filter 26 accommodated in the filter container 34 may also 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 which communicate with a filter accommodation space inside the filter container 34. The filter accommodation space is a space in which the sludge filter 26 is accommodated.

[0018] The first fluid inlet 34-1 and the second fluid inlet 34-2 are, for example, disposed 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 disposed on the side wall of the filter container 34. The fluid outlet 34-3 is, for example, disposed on the lower wall of the filter container 34. The fluid outlet 34-3 may also be disposed 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 pipeline 20. The second fluid inlet 34-2 is connected to the end (downstream end) of the upstream portion 24-1 of the second pipeline 24. The fluid outlet 34-3 is connected to the end (upstream end) of the downstream portion 24-2 of the second pipeline 24. In the case where the machining fluid flows from the fluid outlet 34-3 to the clean water tank 16 by free fall, the downstream portion 24-2 of the second pipeline 24 may also be removed.

[0019] Either the sewage or the clean water is selectively supplied to the sludge filter 26. Sewage is supplied from the sewage tank 14 sequentially through the second pipe 24 and the second fluid inlet 34-2. Clean water is supplied from the clean water tank 16 sequentially through the first pipe 20 and the first fluid inlet 34-1.

[0020] When the waste water is supplied to the sludge filter 26, the sludge filter 26 removes machining chips contained in the waste water. In this case, the machining chips are captured in the pores of the sludge filter 26. The machining fluid (clean water) from which the machining chips are 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 makes the resistivity of the clean water higher 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 that capture the machining chips.

[0022] The on-off valve 28 is provided on the first pipeline 20. The on-off valve 28 is configured to be able to switch 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 closed. The opening and closing of the on-off valve 28 is performed by the control device 32.

[0023] The resistivity meter 30 is provided in the clean water tank 16. The resistivity meter 30 measures the resistivity of the clean water stored in the clean water tank 16, and outputs a signal indicating the resistivity 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 has 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 also be a numerical control device of the electrical discharge machine 10. The control device 32 may also be another control device provided separately from the numerical control device of the electrical discharge machine 10. Another control device has a processor different from the processor included in the numerical control device.

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

[0026] When receiving the filtration start instruction, 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. In addition, the control device 32 closes the on-off valve 28 to prevent the sewage from flowing into the clean water tank 16.

[0027] When the control device 32 receives the filtration end instruction, the second pump 22 is stopped to stop supplying the sewage to the sludge filter 26. In this case, the control device 32 compares the resistivity measured by the resistivity meter 30 with a prescribed threshold value.

[0028] When the resistivity is less than a predetermined threshold value, 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 to open the on-off valve 28, and allows the clean water to pass through the pores of the sludge filter 26 that captures the machining chips. As a result, the resistivity of the clean water is greater than the resistivity of the clean water stored in the clean water tank 16. On the other hand, when the resistivity exceeds the predetermined threshold value, the control device 32 stops the first pump 18 and closes the on-off valve 28.

[0029] The inventors of the present invention have found that when clean water is passed through the pores of a porous body that has captured machining chips, the resistivity of the clean water increases. In the present 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. Machining chips generated by machining of the object to be machined are captured in the pores. Thus, by intentionally passing clean water from which machining chips have been removed through the pores that have captured machining chips, the resistivity of the clean water can be increased. Therefore, the resistivity of the clean water can be improved without using a commonly used ion exchange resin. As a result, the resistivity of the machining fluid can be efficiently improved.

[0030] Furthermore, in this embodiment, the sludge filter 26 is provided on the second pipe 24 that guides the machining fluid from the dirty water tank 14 to the clean water tank 16, and the first pipe 20 guides the clean water to the sludge filter 26. Thus, the sludge filter 26 that increases the specific resistance value of the clean water can be used as a filtration filter. As a result, the resistivity of the machining fluid can be efficiently improved.

[0031] [Modifications] The above-mentioned embodiment may be modified as follows.

[0032] (Variant 1) Figure 2 1 is a schematic diagram showing the structure of the electric discharge machine 10 according to the first modification. Figure 2 In the embodiment, the same reference numerals are given to the same structures as those described in the embodiment. In addition, in this modification, the description overlapping with the embodiment is omitted.

[0033] In this modification, in addition to the sludge filter 26, a permeation filter 36 is further provided. The permeation filter 36 is accommodated 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 portion 24-1 of the second pipe 24 is connected to the fluid inlet 38-1. The end (upstream end) of the downstream portion 24-2 of the second pipe 24 is connected to the fluid outlet 38-2.

[0034] The filter 36 is a porous body having fine pores. The filter 36 removes the machining chips contained in the sewage. In the case where the filter 36 is used once (the sewage passes through the filter 36 once), the machining chips are captured by the fine pores of the filter 36. The used filter 36 is taken out from the filter container 38 when replacing it with an unused filter 36. In this case, the used filter 36 can be used as the sludge filter 26.

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

[0036] In the present modification, the control device 32 compares the resistivity measured by the resistivity meter 30 with a predetermined threshold value, regardless of whether or not the sewage is supplied to the filtration filter 36. If the resistivity becomes less than the predetermined threshold value, the control device 32 continues to supply clean water to the sludge filter 26 until the resistivity exceeds the threshold value.

[0037] According to this modification, even when the sewage is filtered by the filter 36 , the clean water stored in the clean water tank 16 can pass through the pores of the sludge filter 26 , thereby improving the resistivity of the clean water.

[0038] (Variant 2) Figure 3 2 is a schematic diagram showing the structure of the electric discharge machine 10 according to the second modification. Figure 3 In the present invention, the same reference numerals are given to the same structures as those described in the embodiment and the modification 1. In the present modification, the description overlapping with that in the embodiment is omitted.

[0039] In this modification, only the first conduit 20 is different from that in modification 1. In modification 1, the first conduit 20 is formed so that clean water flows to the clean water tank 16 via the sludge filter 26. On the other hand, in this modification, the first conduit 20 is formed so that clean water flows to the sewage tank 14 via the sludge filter 26. That is, in the case of this modification, the downstream portion 20-2 of the first conduit 20 guides the clean water flowing out of the sludge filter 26 to the sewage tank 14.

[0040] Also in this modification, similarly to the modification 1, the resistivity of clean water can be improved.

[0041] (Variant 3) Figure 4 1 is a schematic diagram showing the structure of the electric discharge machine 10 according to the third modification. Figure 4 In the present invention, the same reference numerals are given to the same structures as those described in the embodiment and the modification 1. In the present modification, the description overlapping with that in the embodiment is omitted.

[0042] In this modification, a processing tank 40 is additionally provided. The processing tank 40 is a water tank for storing a processing liquid for immersing a processing object. The processing tank 40 is provided on the upper surface of a setting table 42. In the case of this modification, the first pipeline 20 is formed so that clean water flows to the processing tank 40 via the sludge filter 26. That is, the downstream portion 20-2 of the first pipeline 20 guides the clean water flowing out of the sludge filter 26 to the processing tank 40. In this modification, as in the modification 1, the resistivity of the clean water can be improved.

[0043] In addition, in this modification, a third pipeline 44 is connected to the processing tank 40. The third pipeline 44 guides the processing fluid stored in the processing tank 40 to the sewage tank 14. The third pipeline 44 is provided with an on-off valve 46. The on-off valve 46 is configured to be able to switch the third pipeline 44 to either opening or closing. When the on-off valve 46 is opened, the third pipeline 44 is opened. 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 time such as when the processing of the processing object is completed, and discharges the processing fluid stored in the processing tank 40 into the sewage tank 14. In this case, the control device 32 may open the on-off valve 28 and drive the first pump 18 to supply clean water in an amount corresponding to the amount of the processing fluid discharged into the sewage tank 14 to the processing tank 40. Thus, it is 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] (Variant 4) The resistivity meter 30 may also be replaced by 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 modification, the control device 32 compares the conductivity measured by the conductivity meter with a predetermined threshold value. In addition, in this modification, when the conductivity is greater than the predetermined threshold value, the control device 32 drives the first pump 18 and opens the on-off valve 28. This modification is not limited to the embodiment, and may also be applied to any one of Modifications 1 to 3.

[0046] (Variant 5) The control device 32 may also control the converter that drives the first pump 18 to adjust the flow rate of the clean water in the first pipeline 20. In this case, the switch valve 28 may also be removed. In addition, when the on-off valve 28 is an electromagnetic valve capable of adjusting the opening, the control device 32 may also control the opening of the on-off valve 28 to adjust the flow rate of the clean water in the first pipeline 20. This modification is not limited to the embodiment, and may also be applied to any one of Modifications 1 to 3.

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

[0048] [invention] The invention and effects that can be grasped from the above description are as follows.

[0049] (1) The present invention is an electrical discharge machine (10) that processes a processing object disposed in a processing fluid by electrical discharge, the electrical discharge machine (10) comprising: a sewage tank (14) that stores sewage, the sewage being the processing fluid containing processing chips generated by processing the processing object; a clean water tank (16) that stores clean water, the clean water being the processing fluid with the processing chips removed from the sewage; a first pipeline (20) that guides the clean water drawn from the clean water tank; and a sludge filter (26) that is a porous body having pores for the clean water supplied from the first pipeline to pass through, the pores capturing the processing chips.

[0050] Thus, by intentionally passing clean water from which machining chips have been removed through the pores that have captured machining chips, the specific resistance value of the clean water can be increased. Therefore, the specific resistance value of the clean water can be improved without using the commonly used ion exchange resin. As a result, the resistivity value of the machining fluid can be effectively improved.

[0051] (2) The present invention is an electrical discharge machine, which may also include: a second pipeline (24) that guides the machining fluid from the sewage tank to the clean water tank; a filtration filter (36) that is arranged in the second pipeline and removes the machining chips from the sewage, and the sludge filter may be different from the filtration filter. In this way, the resistivity of the clean water can be improved while removing the machining chips from the sewage.

[0052] (3) The present invention is an electrical discharge machine, wherein the first conduit may be formed so that the clean water flows to the clean water tank via the sludge filter. This stabilizes the resistivity of the clean water stored in the clean water tank.

[0053] (4) The present invention is an electrical discharge machine, wherein the first conduit may be formed so that the clean water flows to the sewage tank via the sludge filter. This stabilizes the resistivity of the sewage stored in the sewage tank.

[0054] (5) The present invention is an electrical discharge machine, wherein the first conduit may be formed so that the clean water flows through the sludge filter to a processing tank (40) storing the processing fluid for immersing the processing object. Thus, the resistivity of the processing fluid stored in the processing tank can be stabilized. As a result, a significant increase in the ion concentration of the processing fluid, which may lead to a decrease in processing accuracy, can be suppressed.

[0055] (6) The present invention is an electrical discharge machine, which may also include a second pipeline that guides the machining fluid from the dirty water tank to the clean water tank, the sludge filter is provided in the second pipeline, and the first pipeline guides the clean water to the sludge filter. Thus, the sludge filter that increases the resistivity of the clean water can be used as a filtering filter. As a result, the resistivity of the machining fluid can be efficiently improved.

[0056] (7) The present invention is an electrical discharge machine, wherein the sludge filter may be the porous body for removing the machining chips. Thus, the filtration filter can be recycled as the sludge filter.

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

[0058] (9) The present invention is an electrical discharge machine, which may also include: a resistivity meter (30) for measuring the resistivity of the clean water; a pump for drawing the clean water from the clean water tank; and a control device (32) for controlling the pump to draw the clean water into the pump when the resistivity is below a predetermined threshold value. Thus, an increase in the ion concentration of the clean water can be reliably suppressed.

[0059] In addition, the present invention is not limited to the above disclosure, and various structures can be adopted without departing from the gist of the present invention. Explanation of symbols

[0060] 10…Electrical discharge 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 valve 30...Resistivity meter 32 ... control device 34, 38 ... filter container 36 ... filter 40 ... processing tank.

Claims

1. An electrical discharge machine (10) for processing an object to be processed disposed in a processing fluid by electrical discharge, characterized in that: have: a sewage tank (14) storing sewage, the sewage being the processing fluid containing processing chips generated by processing the processing object; a clean water tank (16) storing clean water, which is the processing fluid obtained by removing the processing chips from the waste water; A first pipeline (20) for guiding the clean water drawn from the clean water tank; as well as The sludge filter (26) is a porous body having pores through which the clean water supplied from the first pipe passes, and the processing chips are captured in the pores.

2. The electrical discharge machine according to claim 1, wherein: have: a second pipeline (24) for guiding the processing fluid from the sewage tank to the clean water tank; and A filter (36) is provided in the second pipeline to remove the machining chips from the sewage. The sludge filter is distinct from the filtration filter.

3. The electrical discharge machine according to claim 2, wherein: The first pipe is formed so that the clean water flows to the clean water tank via the sludge filter.

4. The electrical discharge machine according to claim 2, wherein: The first pipe is formed so that the clean water flows to the sewage tank via the sludge filter.

5. The electrical discharge machine according to claim 2, wherein: The first pipe is formed so that the clean water flows through the sludge filter to a processing tank (40) storing the processing fluid for immersing the processing object.

6. The electrical discharge machine according to claim 1, wherein: A second pipeline is provided, which guides the processing fluid from the sewage tank to the clean water tank, The sludge filter is arranged in the second pipeline, The first pipe guides the clean water to the sludge filter.

7. The electrical discharge machine according to any one of claims 2 to 6, characterized in that: The sludge filter is the porous body for removing the machining chips.

8. The electrical discharge machine according to any one of claims 1 to 7, characterized in that The machining chips include at least one of iron, aluminum, copper, zinc, cemented carbide, tungsten, molybdenum, carbon, titanium, silicon, manganese, chromium, phosphorus, sulfur and nickel.

9. The electrical discharge machine according to any one of claims 1 to 8, characterized in that have: A resistivity meter (30) for measuring the resistivity of the clean water; a pump (18) for drawing the clean water from the clean water tank; and The control device (32) controls the pump to pump the clean water into the pump when the resistivity is equal to or less than a predetermined threshold value.

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