Electrical discharge machine

Abstract

One embodiment of the electrical discharge machining (EDM) machine (10) includes: a pump (52) for supplying liquid; and an inlet pipe (54) for introducing the liquid supplied by the pump (52) into a machining tank (46). The inlet pipe (54) has a pipe section (54PT) higher than the maximum allowable water level height of the machining tank (46). A through hole (54H) is provided in the pipe section (54PT) through the pipe wall of the inlet pipe (54).

Description

Technical Field

[0001] This invention relates to an electrical discharge machining (EDM) machine that performs electrical discharge machining on a workpiece in a liquid stored in a processing tank. Background Technology

[0002] In electrical discharge machining (EDM) machines, a device is provided for supplying liquid stored in the machining tank. Japanese Patent Application Publication No. 2017-019046 discloses a machining fluid supply device having a pump (circulating pump) and a first liquid circuit. The pump draws liquid (clean water) from a clean water tank. The first liquid circuit supplies the liquid drawn by the pump to the machining tank. While Japanese Patent Application Publication No. 2017-019046 does not provide a specific description of the first liquid circuit, piping is generally used as the first liquid circuit. A check valve to prevent backflow from the machining tank is generally installed on this piping. Summary of the Invention

[0003] However, removing the check valve from the piping for maintenance or other purposes is a complex operation.

[0004] Therefore, the purpose of this invention is to provide an electrical discharge machining machine that can suppress the backflow of liquid from the machining tank without the need for a check valve.

[0005] The present invention provides an electrical discharge machining (EDM) machine for performing electrical discharge machining on a workpiece in a liquid stored in a processing tank, comprising: a pump for supplying the liquid; an inlet pipe for introducing the liquid supplied by the pump into the processing tank; and a through hole penetrating the wall of the inlet pipe, wherein the inlet pipe has a portion that is higher than the maximum allowable water level height of the processing tank, and the through hole is provided in the portion of the inlet pipe.

[0006] According to the present invention, backflow of liquid from the processing tank can be suppressed without the need for a check valve. Specifically, the piping section leading to the piping is higher than the maximum allowable water level in the processing tank. Therefore, when the pump stops, the liquid filling the flow path of the piping section is discharged through the through-hole by gravity, accumulating air in the flow path of the piping section. Thus, the air accumulated in the flow path of the piping section can be used to suppress backflow from the processing tank. In this way, backflow of liquid from the processing tank can be suppressed without the need for a check valve. Attached Figure Description

[0007] Figure 1 This is a schematic diagram showing the structure of the electrical discharge machining machine according to the embodiment.

[0008] Figure 2 This is a schematic diagram showing a portion of the structure of the processing fluid treatment device.

[0009] Figure 3 This is a diagram showing the process of supplying liquid to the processing tank. Detailed Implementation

[0010] [Implementation Method]

[0011] Figure 1 This is a schematic diagram showing the structure of the electrical discharge machining (EDM) machine 10 according to an embodiment. Figure 1 The diagram shows the X, Y, and Z directions. Furthermore, the X and Y directions are orthogonal to each other within the plane, and the Z direction is orthogonal to both the X and Y directions.

[0012] The electrical discharge machining (EDM) machine 10 is a machine that performs electrical discharge machining on a workpiece in a liquid. The EDM machine 10 processes the workpiece by applying a voltage between the workpiece and the wire electrode 12, thereby generating a discharge between the electrodes. The EDM machine 10 includes a machining body 14, a machining fluid treatment device 16, and a control device 18 that controls the machining body 14 and the machining fluid treatment device 16.

[0013] The material of the wire electrode 12 is, for example, a tungsten-based, copper-alloy-based, or brass-based metal. On the other hand, the material of the workpiece being processed is, for example, an iron-based or superhard metal.

[0014] The main body of the processing machine 14 has a supply system 20 for supplying wire electrodes 12 to the object being processed (workpiece, workpiece) and a recovery system 22 for recovering wire electrodes 12 that have passed through the object being processed.

[0015] The supply system 20 includes a spool 24, a torque motor 26, a brake pad 28, a brake motor 30, a tension detection unit 32, and an upper mold guide 34. Unused wire electrodes 12 are wound onto the spool 24. The torque motor 26 applies torque to the spool 24. The brake pad 28 applies a braking force generated by friction to the wire electrodes 12. The brake motor 30 applies a braking torque to the brake pad 28. The tension detection unit 32 detects the tension of the wire electrodes 12. The upper mold guide 34 guides the wire electrodes 12 above the workpiece.

[0016] The recovery system 22 includes a lower die guide 36, a clamping roller 38, a feed roller 40, a torque motor 42, and a recovery box 44. The lower die guide 36 guides the wire electrode 12 below the workpiece. The clamping roller 38 and the feed roller 40 can clamp the wire electrode 12. The torque motor 42 applies torque to the feed roller 40. The recovery box 44 recovers the wire electrode 12 conveyed by the clamping roller 38 and the feed roller 40.

[0017] The main body 14 of the processing machine has a processing tank 46 for storing processing fluid. The processing fluid is a liquid used during processing. For example, deionized water can be used as a processing fluid. The processing tank 46 is placed on a base 48. An upper mold guide 34 and a lower mold guide 36 are arranged in the processing tank 46, and a workpiece is placed between the upper mold guide 34 and the lower mold guide 36. The upper mold guide 34, the lower mold guide 36, and the workpiece are immersed in the processing fluid stored in the processing tank 46.

[0018] The upper mold guide 34 has a support portion 34a for supporting the wire electrode 12, and the lower mold guide 36 has a support portion 36a for supporting the wire electrode 12. Additionally, the lower mold guide 36 includes a guide roller 36b. The guide roller 36b changes the orientation of the wire electrode 12 and guides the wire electrode 12 to the pinch roller 38 and the feed roller 40.

[0019] Furthermore, the upper mold guide 34 sprays clean machining fluid, free of sludge (machining chips), into the space between the wire electrode 12 and the workpiece. This allows the space between the electrodes to be filled with a clean liquid suitable for machining, preventing a decrease in machining accuracy due to sludge generated during machining. Additionally, the lower mold guide 36 can also spray clean machining fluid, free of sludge (machining chips), into the space between the electrodes.

[0020] The processing fluid treatment device 16 is a device that manages the quality of the processing fluid by removing sludge generated in the processing tank 46 and adjusting resistivity, temperature, etc. The processing fluid managed by the processing fluid treatment device 16 is returned to the processing tank 46 and is ejected from at least the upper mold guide 34.

[0021] Figure 2 This is a schematic diagram showing a portion of the structure of the processing fluid treatment apparatus 16. The processing fluid treatment apparatus 16 includes a storage tank 50, a pump 52, an inlet pipe 54, an outlet fluid storage tank 56, and an outlet pipe 58.

[0022] The storage tank 50 stores the liquid supplied by the pump 52. The storage tank 50 can also be a wastewater tank for storing processing fluid (sludge) containing sludge. Alternatively, the storage tank 50 can also be a clean water tank for storing processing fluid (clean water) from a wastewater tank through a filter that removes sludge.

[0023] Pump 52 draws liquid stored in storage tank 50 and supplies the drawn liquid downstream. Pump 52 is driven by control device 18. For example, after receiving a processing start command, control device 18 drives pump 52 until the water level of the liquid stored in processing tank 46 is detected by a sensor to reach a preset value.

[0024] The inlet pipe 54 introduces the liquid supplied by the pump 52 into the processing tank 46. One end of the inlet pipe 54 is connected to the output end of the pump 52. The other end of the inlet pipe 54 is connected to the connecting mechanism 60. The connecting mechanism 60 communicates with the inlet pipe 54 through a hole 46H that passes through the side wall 46W of the processing tank 46. This connecting mechanism 60 is capable of storing the liquid flowing in the inlet pipe 54.

[0025] The inlet piping 54 has a piping section 54PT that is higher than the maximum allowable water level height of the processing tank 46. The piping section 54PT may also be higher than the upper end of the processing tank 46 (see reference). Figure 2 Additionally, the 54PT piping section can be installed horizontally (see reference). Figure 2 At least a portion of the piping section 54PT can also be inclined. Furthermore, the maximum allowable water level height of the processing tank 46 is a fixed value predetermined based on the capacity of the processing tank 46, and is lower than the height of the upper end of the processing tank 46. A connecting mechanism 60 is provided at a position lower than this maximum value. Additionally, when processing an object, a mold guide 34 is positioned at a position lower than the maximum allowable water level height of the processing tank 46. Figure 1 The upper mold guide 34 is moved by a motor controlled by the control device 18.

[0026] A through hole 54H is provided in the piping section 54PT, penetrating the wall of the inlet pipe 54. The through hole 54H is located in the direction of gravity (downward) relative to the imaginary centerline LN passing through the center of the cross-section of the inlet pipe 54. Alternatively, a portion of the through hole 54H may be located in the direction opposite to gravity (upward) relative to the imaginary centerline LN. Furthermore, the through hole 54H may be located in the middle of the inlet pipe 54, or in a location other than the middle (see reference). Figure 2 ).

[0027] The cross-sectional area of ​​the through hole 54H can be the same as or different from the cross-sectional area of ​​the flow path (cavity) of the piping section 54PT. When the cross-sectional area of ​​the through hole 54H is different from the cross-sectional area of ​​the flow path of the piping section 54PT, the cross-sectional area of ​​the through hole 54H is preferably smaller than the cross-sectional area of ​​the flow path of the piping section 54PT.

[0028] The drain fluid storage tank 56 stores the liquid flowing out from the through hole 54H. The drain fluid storage tank 56 can also be positioned further down (in the direction of gravity) than the machining tank 46 (see reference). Figure 2 Alternatively, it can be positioned on the same surface as the processing tank 46. Furthermore, the drain fluid storage tank 56 can also be positioned on the same surface as the storage tank 50 (see reference). Figure 2 It can also be set on a different face than the one set here.

[0029] The drain liquid storage tank 56 is connected to the storage tank 50 via a connecting pipe 62. The connecting pipe 62 is a pipe that connects the drain liquid storage tank 56 and the storage tank 50, and a valve 64 is provided on the connecting pipe 62. The valve 64 is opened and closed under the control of the control device 18. For example, the control device 18 opens the valve 64 until a predetermined time has elapsed after the sensor detects that the liquid storage level in the storage tank 50 has fallen below a predetermined amount.

[0030] The outlet pipe 58 guides the liquid flowing from the through hole 54H to the outlet liquid storage tank 56. The outlet pipe 58 extends in the direction of gravity (downward). One end of the outlet pipe 58 is connected to the inlet pipe 54. The other end of the outlet pipe 58 opens into the outlet liquid storage tank 56.

[0031] The cross-sectional area of ​​the flow path (cavity portion) of the outgoing pipe 58 can be the same as or different from the cross-sectional area of ​​the flow path (cavity portion) of the incoming pipe 54. When the cross-sectional area of ​​the flow path of the outgoing pipe 58 is different from that of the incoming pipe 54, the cross-sectional area of ​​the flow path of the outgoing pipe 58 is preferably smaller than that of the flow path of the incoming pipe 54. Furthermore, when the cross-sectional area of ​​the through hole 54H provided in the incoming pipe 54 is smaller than the cross-sectional area of ​​the flow path in the pipe section 54PT, the cross-sectional area of ​​the flow path of the outgoing pipe 58 can also be larger than that of the flow path of the incoming pipe 54.

[0032] Figure 3 This diagram illustrates the supply of liquid to the processing tank 46. If the liquid stored in the storage tank 50 is supplied to the inlet pipe 54 via the pump 52, it flows downstream of the pump 52.

[0033] A portion of the liquid flowing in the inlet pipe 54 flows from the through hole 54H provided in the pipe section 54PT to the outlet pipe 58. Liquid that does not flow through the outlet pipe 58 flows into the tank through the hole 46H provided in the side wall 46W of the processing tank 46 via the connecting mechanism 60. On the other hand, the liquid flowing through the outlet pipe 58 flows into the outlet liquid storage tank 56. Furthermore, the liquid flowing into the outlet liquid storage tank 56 returns to the storage tank 50 via the connecting pipe 62 when the valve 64 is opened by the control device 18.

[0034] In this embodiment, the piping portion 54PT of the inlet pipe 54 is higher than the maximum allowable water level height of the processing tank 46. Therefore, when the pump 52 stops, the liquid filling the flow path (cavity portion) of the piping portion 54PT falls out of the through hole 54H due to its own weight. As a result, air accumulates in the flow path of the piping portion 54PT (see reference). Figure 2Therefore, the backflow from the processing tank 46 can be suppressed by utilizing the air accumulated in the flow path of the piping section 54PT. Thus, according to this embodiment, it is possible to suppress the backflow of liquid from the processing tank 46 without installing a check valve.

[0035] Furthermore, when the piping section 54PT is higher than the upper end of the machining tank 46, the flow rate up to the point where air accumulates in the piping section 54PT can be increased compared to when the piping section 54PT is lower than the upper end of the machining tank 46. Additionally, when the through-hole 54H is positioned closer to the direction of gravity than the imaginary centerline LN, the liquid filling the flow path (cavity portion) of the piping section 54PT can be efficiently discharged from the through-hole 54H by its own weight when the pump 52 stops.

[0036] Furthermore, when the cross-sectional area of ​​the through hole 54H is smaller than the cross-sectional area of ​​the flow path (cavity) of the piping section 54PT, the liquid flowing to the processing tank 46 through the piping section 54PT is less likely to flow out through the through hole 54H. That is, when liquid is supplied from the storage tank 50 to the processing tank 46, the amount of liquid flowing out through the through hole 54H can be reduced.

[0037] In this embodiment, a drain liquid storage tank 56 is provided to store the liquid flowing out from the through hole 54H. This reduces the scattering of liquid flowing out from the through hole 54H to the outside by the wall of the drain liquid storage tank 56. Therefore, it is possible to suppress the unexpected outflow of liquid from the through hole 54H to the surrounding area. Alternatively, the drain liquid storage tank 56 may not be provided.

[0038] In this embodiment, the drain liquid storage tank 56 is connected to the storage tank 50, which stores the liquid supplied by the pump 52, via a connecting pipe 62. This allows the liquid stored in the drain liquid storage tank 56 to return to the storage tank 50, reducing waste of liquid supplied to the processing tank 46. Alternatively, the connecting pipe 62 may be omitted. Without the connecting pipe 62, the valve 64 installed on the connecting pipe 62 is also omitted.

[0039] Furthermore, in this embodiment, a discharge pipe 58 is provided, which is connected to the inlet pipe 54 and guides the liquid flowing from the through hole 54H to the discharge liquid storage tank 56. Therefore, compared to the case without the discharge pipe 58, the scattering of liquid flowing from the through hole 54H can be reduced. When the cross-sectional area of ​​the flow path (cavity portion) of the discharge pipe 58 is smaller than the cross-sectional area of ​​the flow path (cavity portion) of the inlet pipe 54, the liquid flowing to the processing tank 46 through the pipe section 54PT is less likely to flow out from the through hole 54H. That is, when liquid is supplied from the storage tank 50 to the processing tank 46, the amount of liquid flowing out from the through hole 54H can be reduced. Alternatively, the discharge pipe 58 may not be provided.

[0040] [Variation Example]

[0041] The implementation method described herein can also be modified as follows.

[0042] In one embodiment, the electrical discharge machining (EDM) machine 10 is a wire EDM machine that processes the workpiece by generating a discharge between the wire electrode 12 and the workpiece. However, the EDM machine 10 can also be an electrical discharge machining (EDM) machine that processes the workpiece by generating a discharge between the electrode used for electrical discharge forming and the workpiece. Furthermore, when the EDM machine 10 is an EDM machine for electrical discharge forming, it does not have a supply system 20 or a recovery system 22. In this case, a worktable for fixing the workpiece and an electrode for electrical discharge forming are arranged in the groove of the machining tank 46. Additionally, an actuator is provided to move the worktable relative to the electrode for electrical discharge forming, and this actuator is controlled by a control device 18.

[0043] [Inventions that can be understood from their implementation methods and variations]

[0044] The invention described below can be understood from the described embodiments and variations.

[0045] The present invention is an electrical discharge machining (EDM) machine 10 that performs EDM on a workpiece in a liquid stored in a processing tank 46, comprising: a pump 52 that supplies liquid; an inlet pipe 54 that introduces the liquid supplied by the pump into the processing tank; and a through hole 54H that penetrates the wall of the inlet pipe, the inlet pipe having a pipe portion 54PT that is higher than the maximum allowable water level height of the processing tank, and the through hole being provided in the pipe portion.

[0046] Therefore, backflow of liquid from the processing tank can be suppressed without installing a check valve. Specifically, the piping section leading to the piping is higher than the maximum allowable water level in the processing tank. Consequently, when the pump stops, the liquid filling the flow path of the piping section falls through the through-hole due to its own weight, accumulating air in the flow path of the piping section. Therefore, the air accumulated in the flow path of the piping section can be used to suppress backflow from the processing tank. Thus, backflow of liquid from the processing tank can be suppressed without installing a check valve.

[0047] The piping section can also be higher than the top of the processing tank. Therefore, compared to the case where the piping section is lower than the top of the processing tank, the flow rate up to the point where air accumulates in the piping section can be increased.

[0048] The through-hole can also be positioned closer to the direction of gravity than the imaginary centerline LN passing through the center of the cross-section of the inlet pipe. This allows the liquid filling the flow path of the pipe section when the pump stops to be efficiently discharged through the through-hole by its own weight.

[0049] The cross-sectional area of ​​the through hole can also be smaller than the cross-sectional area of ​​the flow path in the piping section. Therefore, when the liquid flows to the processing tank through the piping section, the amount of liquid diverted from the through hole can be reduced.

[0050] The electrical discharge machining machine can also be equipped with a discharge fluid storage tank 56 for storing the liquid discharged from the through hole. This reduces the amount of liquid discharged from the through hole that splashes into the surrounding area.

[0051] The electrical discharge machining (EDM) machine may also be equipped with a discharge pipe 58, which connects to the inlet pipe to guide the liquid discharged from the through-hole to the discharge liquid storage tank. This reduces the amount of liquid discharged from the through-hole that splashes into the surrounding area.

[0052] The cross-sectional area of ​​the flow path in the outgoing piping can also be smaller than that in the incoming piping. This reduces the amount of liquid diverted from the through-hole when the liquid flows to the processing tank through the piping.

[0053] The electrical discharge machining (EDM) machine may also include: a storage tank 50 for storing the liquid supplied by the pump; and a connecting pipe 62 connecting the outlet liquid storage tank to the storage tank. This allows the liquid stored in the outlet liquid storage tank to return to the storage tank, reducing waste of liquid supplied to the machining tank.

Claims

1. An electrical discharge machining (EDM) machine (10) for performing electrical discharge machining on a workpiece in a liquid stored in a machining tank (46), characterized in that, The electrical discharge machining (10) has the following features: Pump (52), which supplies the liquid; The inlet piping (54) introduces the liquid supplied by the pump into the processing tank; and A through hole (54H) penetrates the wall of the inlet pipe. The inlet piping has a piping section (54PT) that is higher than the maximum allowable water level height of the processing tank. The through hole is located in the piping section. When the pump stops, the liquid filling the flow path of the piping section falls through the through hole due to its own weight, causing air to accumulate in the flow path.

2. The electrical discharge machining machine according to claim 1, characterized in that, The piping section is higher than the upper end of the processing tank.

3. The electrical discharge machining machine according to claim 1 or 2, characterized in that, The through hole is located closer to the direction of gravity than the imaginary centerline (LN) passing through the center of the cross-section of the inlet pipe.

4. The electrical discharge machining machine according to claim 1 or 2, characterized in that, The cross-sectional area of ​​the through hole is smaller than the cross-sectional area of ​​the flow path in the piping section.

5. The electrical discharge machining machine according to claim 1, characterized in that, The electrical discharge machining machine is equipped with an outlet liquid storage tank (56) for storing the liquid discharged from the through hole.

6. The electrical discharge machining machine according to claim 5, characterized in that, The electrical discharge machining machine is equipped with an outlet pipe (58) connected to the inlet pipe, which guides the liquid discharged from the through hole to the outlet liquid storage tank.

7. The electrical discharge machining machine according to claim 6, characterized in that, The cross-sectional area of ​​the flow path of the outgoing pipe is smaller than the cross-sectional area of ​​the flow path of the incoming pipe.

8. The electrical discharge machining machine according to any one of claims 5 to 7, characterized in that, The electrical discharge machining machine includes: a storage tank (50) for storing the liquid supplied by the pump; and a connecting pipe (62) connecting the outlet liquid storage tank to the storage tank.

Images