Electric discharge machining apparatus

Abstract

The electric discharge machining apparatus (100) includes a machining tank (1) that houses an electrode and a workpiece and stores a machining fluid (7), and a power supply device (3) that supplies current between the electrodes. The power supply device (3) includes a power supply housing (31) disposed on the outer surface (1g) of the machining tank (1), a plurality of substrates (33) housed in the power supply housing (31) and having heating elements (33a), a water-cooling pipe (36) housed in the power supply housing (31) through which a cooling medium flows, and heat dissipation fins (37) housed in the power supply housing (31) and contacting the heating elements (33a) and the water-cooling pipe (36) of each of the plurality of substrates (33). The power supply housing (31) has a substrate plane (31a) facing the outer surface (1g) of the machining tank (1). The plurality of substrates (33) are arranged offset from each other in the direction perpendicular to the substrate plane (31a). The heat dissipation fins (37) have different structures or different dimensions according to the heat generation amounts of the heating elements (33a) for each substrate (33).

Description

Technical Field

[0001] The present disclosure relates to an electric discharge machining apparatus that generates an electric discharge between electrodes formed between an electrode and a workpiece in a machining tank and machines the workpiece by the arc heat of the electric discharge.

Background Art

[0002] Conventionally, an electric discharge machining apparatus is known that generates an electric discharge between electrodes formed between an electrode and a workpiece in a machining tank and machines the workpiece by the arc heat of the electric discharge. The electric discharge machining apparatus includes a power supply device that supplies current and voltage between the electrodes.

[0003] Generally, machining characteristics such as the surface roughness of the machined surface of the workpiece and the dimensions of the workpiece after machining are affected by the current supplied from the power supply device between the electrodes during electric discharge. Therefore, when the current changes, the machining characteristics also change.

[0004] Since the current supplied between the electrodes has a very short pulse shape, it is affected by parasitic impedances such as parasitic inductance and stray capacitance derived from the connection conductor between the electrodes and the power supply device. In particular, if there is a distance between the electrodes and the power supply device, the connection conductor becomes longer accordingly, and the current decays due to the parasitic inductance, which may make it difficult to obtain desired machining characteristics. Also, when the connection conductor is a cable, even if the length, thickness, number, etc. of the cable are uniquely designed, a misalignment of the cable arrangement occurs due to assembly errors and the like that occur for each electric discharge machining apparatus. As a result, a difference occurs in the parasitic inductance, and variations occur in the machining quality of the workpiece.

[0005] Therefore, in order to shorten the distance between the electrodes and the power supply device, it is preferable to bring the power supply device as close as possible to the electrodes. For example, Patent Document 1 discloses a technique for miniaturizing the entire power supply device by arranging a plurality of substrates on the same plane (in a row in a direction parallel to one plane of the power supply device) and directly attaching the power supply device to the outer surface of the machining tank. Further, Patent Document 1 discloses a technique of providing a water-cooling pipe through which a cooling medium flows inside the power supply device along the direction in which a plurality of substrates are arranged in a row in order to cool electronic components (hereinafter referred to as heat-generating elements) on each substrate.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the technique disclosed in Patent Document 1, since a plurality of substrates are arranged on the same plane, the water-cooling pipe becomes long, and the cooling efficiency for the heat-generating elements for each substrate is likely to be uneven. As a result, the temperature of the heat-generating elements for each substrate is likely to become non-uniform, and differences occur in the pulse shapes of the output current waveforms for each substrate due to the temperature characteristics of the heat-generating elements.

[0008] The present disclosure has been made in view of the above, and an object thereof is to obtain an electric discharge machining apparatus in which differences in the pulse shapes of the output current waveforms for each substrate are less likely to occur due to the temperature characteristics of the heat-generating elements.

Means for Solving the Problems

[0009] In order to solve the above-described problems and achieve the object, an electric discharge machining apparatus according to the present disclosure is an electric discharge machining apparatus that generates an electric discharge between electrodes formed between an electrode and a workpiece, and machines the workpiece by the arc heat of the electric discharge, and includes a machining tank and a power supply device. The machining tank accommodates the electrode and the workpiece and stores a machining fluid. The power supply device supplies a current between the electrodes. The power supply device includes a power supply housing disposed on the outer surface of the machining tank, and a plurality of substrates accommodated in the power supply housing and having heating elements. Further, the power supply device includes a water cooling pipe accommodated in the power supply housing through which a cooling medium flows, and heat dissipation fins accommodated in the power supply housing and contacting the heating elements of the respective substrates and the water cooling pipe. The power supply housing has a substrate plane facing the outer surface of the machining tank. The plurality of substrates are arranged offset from each other in the direction perpendicular to the substrate plane. The heat dissipation fins have different structures or different dimensions according to the heat generation amount of the heating elements for each substrate.

Advantages of the Invention

[0010] The electric discharge machining apparatus according to the present disclosure has an effect that differences are less likely to occur in the pulse shape of the output current waveform for each substrate due to the temperature characteristics of the heating elements.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0012] The electric discharge machining apparatus according to the embodiment will be described in detail below with reference to the drawings.

[0013] Embodiment 1. FIG. 1 is an explanatory diagram showing the configuration of an electric discharge machining apparatus 100 according to Embodiment 1. FIG. 2 is a plan view showing the configuration of a machining tank 1 and a power supply device 3 of the electric discharge machining apparatus 100 according to Embodiment 1. As shown in FIG. 1, the electric discharge machining apparatus 100 includes a machining tank 1, a connection conductor 2, and a power supply device 3. The electric discharge machining apparatus 100 applies a voltage pulse controlled by the power supply device 3 to an interelectrode gap 6 formed between an electrode 4 and a workpiece 5, generates an electric discharge in the interelectrode gap 6, and melts the workpiece 5 by the arc heat of the electric discharge for machining. The electric discharge machining apparatus 100 is a die-sinking electric discharge machining apparatus in the present embodiment, but may be a wire electric discharge machining apparatus having the electrode 4 as a wire, or a micro-hole electric discharge machining apparatus having the electrode 4 as a rod-shaped electrode or a hollow rod-shaped electrode.

[0014] Hereinafter, when explaining the directions of the respective components of the electric discharge machining apparatus 100, the left-handed XYZ coordinates shown in FIG. 2 are followed. The X-axis, Y-axis, and Z-axis are three mutually perpendicular axes. Among the respective axes, the direction of the arrow is the + direction, and the direction opposite to the arrow is the - direction. The direction along the X-axis (X-axis direction) is the direction in which the machining tank 1 and the power supply device 3 face each other and is a direction included in the horizontal direction. The direction along the Y-axis (Y-axis direction) is a direction perpendicular to the X-axis direction and is a direction included in the horizontal direction. The direction along the Z-axis (Z-axis direction) is a direction perpendicular to the X-axis direction and the Y-axis direction and coincides with the vertical direction (up-and-down direction). Hereinafter, the + direction of the Z-axis is the upward direction, and the - direction of the Z-axis is the downward direction.

[0015] As shown in FIG. 1, the processing tank 1 serves to accommodate the electrode 4 and the workpiece 5 and store the processing fluid 7. The electrode 4 and the workpiece 5 are immersed in the processing fluid 7 in the processing tank 1. The processing fluid 7 plays a role in cooling the electrode 4 and the workpiece 5, preventing fires, and removing processing chips generated by electrical discharge machining. Examples of the material of the workpiece 5 include materials such as tungsten, molybdenum, silicon carbide, single-crystal silicon, single-crystal silicon carbide, gallium nitride, and polycrystalline silicon. Silicon carbide is also referred to as silicon carbide.

[0016] The shape of the processing tank 1 is a box shape that is open upward. As shown in FIGS. 1 and 2, the processing tank 1 has a bottom wall 1a, a front wall 1b, a rear wall 1c, and a pair of side walls 1d and 1e. As shown in FIG. 2, the bottom wall 1a is a square and horizontal wall. The front wall 1b, the rear wall 1c, and the side walls 1d and 1e rise from the periphery of the bottom wall 1a. The front wall 1b is a vertical wall that faces the operator when performing electrical discharge machining operations. The rear wall 1c is a vertical wall that is located on the opposite side of the operator with the front wall 1b in between. The side wall 1d is a vertical wall that connects the one ends of the front wall 1b and the rear wall 1c in the Y-axis direction. The side wall 1e is a vertical wall that connects the other ends of the front wall 1b and the rear wall 1c in the Y-axis direction. Hereinafter, the surface facing the inside of the processing tank 1 among the respective walls of the processing tank 1 is referred to as the inner surface 1f, and the surface facing the outside of the processing tank 1 among the respective walls of the processing tank 1 is referred to as the outer surface 1g.

[0017] As shown in FIG. 1, the connection conductor 2 is a conductor that electrically connects the electrode 4 and the workpiece 5 to the power supply device 3, respectively. That is, the connection conductor 2 electrically connects the inter-pole 6 and the power supply device 3. The connection conductor 2 is, for example, a cable or a copper plate. The connection conductor 2 enables wiring from each power supply board 34 described later to the inter-pole 6, and parasitic impedance 8 is inevitably generated by the wiring. The parasitic impedance 8 often does not become as designed as described above, and becomes a factor that hinders high-precision machining by the electrical discharge machining apparatus 100.

[0018] The power supply device 3 is a device that supplies current and voltage to the gap 6. The power supply device 3 is electrically connected to each of the electrode 4 and the workpiece 5 via the connection conductor 2. The power supply device 3 includes a power supply housing 31, a stabilized power supply 32, and a plurality of substrates 33. Also, as shown in FIG. 2, the power supply device 3 includes a water-cooling pipe 36 and a plurality of heat-radiating fins 37.

[0019] The power supply housing 31 is disposed on the outer surface 1g of the rear wall 1c of the processing tank 1, that is, on the back surface of the processing tank 1. The power supply housing 31 may be disposed on the outer surface 1g of the walls other than the rear wall 1c and the bottom wall 1a. The power supply housing 31 serves to accommodate the plurality of substrates 33, the water-cooling pipe 36, and the plurality of heat-radiating fins 37. The shape of the power supply housing 31 is box-shaped. The substrate 33, the heat-radiating fin 37, and the holding member 38 described later, which are housed in the power supply housing 31, are not actually visible, but in each figure after FIG. 2, each member is illustrated by a solid line. The power supply housing 31 has a substrate plane 31a facing the outer surface 1g of the rear wall 1c of the processing tank 1. The substrate plane 31a is an attachment surface to be attached to the processing tank 1. The substrate plane 31a is a plane extending in the Y-axis direction and the Z-axis direction. The substrate plane 31a is parallel to the outer surface 1g of the rear wall 1c of the processing tank 1 and faces the outer surface 1g of the rear wall 1c of the processing tank 1 with a gap therebetween.

[0020] As shown in FIG. 1, the stabilized power supply 32 is a power supply for supplying a current (direct current) used for electrical discharge machining to the gap 6. The stabilized power supply 32 may be installed either inside or outside the power supply housing 31. In the present embodiment, an example is shown in which the stabilized power supply 32 is installed outside the power supply housing 31 in order to minimize the size of the power supply housing 31 as much as possible.

[0021] As shown in FIG. 2, each of the plurality of substrates 33 is housed in the power supply housing 31 and has a plurality of heat generating elements 33a which are electronic components. The substrate 33 is a printed circuit board. The plurality of substrates 33 are arranged so as to be displaced from each other in the direction perpendicular to the substrate plane 31a. The direction perpendicular to the substrate plane 31a is the direction that coincides with the X-axis direction. Hereinafter, the X-axis direction may also be referred to as the direction perpendicular to the substrate plane 31a. Each of the plurality of substrates 33 has a plurality of output terminals 33b. The distance from the output terminal 33b to the processing tank 1 is different for each substrate 33. A part of each of the plurality of substrates 33 overlaps with another substrate 33 when viewed along the direction perpendicular to the substrate plane 31a. The heat generating element 33a of each of the plurality of substrates 33 is preferably a wide bandgap semiconductor. The substrate 33 is a power supply substrate 34 or an oscillation substrate 35. The power supply substrate 34 is a substrate that is electrically connected to the pole 6. The oscillation substrate 35 is a substrate that controls the current supplied from the stabilized power supply 32 (see FIG. 1) by switching.

[0022] In the illustrated example, the power supply device 3 has a plurality of power supply substrates 34 and one oscillation substrate 35. In the present embodiment, an example in which the number of power supply substrates 34 is three and the number of oscillation substrates 35 is one is illustrated, but the number is not limited. Hereinafter, when distinguishing the three power supply substrates 34, they are referred to as a power supply substrate 34A, a power supply substrate 34B, and a power supply substrate 34C. The three power supply substrates 34A to 34C are arranged side by side in the Y-axis direction while partially overlapping in the Y-axis direction. Each of the power supply substrates 34A to 34C is electrically connected to the pole 6 (see FIG. 1) via the connection conductor 2. The oscillation substrate 35 is arranged away from the power supply substrate 34B in the - direction in the X-axis direction of the power supply substrate 34B located at the center in the Y-axis direction.

[0023] When viewed along the vertical direction of the substrate plane 31a, the entire power supply substrate 34B and the entire oscillation substrate 35 overlap each other. A part of the power supply substrate 34A is arranged between the power supply substrate 34B and the oscillation substrate 35 in the X-axis direction and is spaced apart from both the power supply substrate 34B and the oscillation substrate 35. When viewed along the vertical direction of the substrate plane 31a, a part of the power supply substrate 34A, a part of the power supply substrate 34B, and a part of the oscillation substrate 35 overlap each other. A part of the power supply substrate 34C is arranged between the power supply substrate 34B and the oscillation substrate 35 in the X-axis direction and is spaced apart from both the power supply substrate 34B and the oscillation substrate 35. When viewed along the vertical direction of the substrate plane 31a, a part of the power supply substrate 34C, a part of the power supply substrate 34B, and a part of the oscillation substrate 35 overlap each other.

[0024] Each of the plurality of substrates 33 is connected to the substrate plane 31a or to another substrate 33 via a holding member 38 extending in the X-axis direction. The holding member 38 is a spacer or the like. An insulating spacer may be used as the spacer. Specifically, each of the power supply substrates 34A to 34C is connected to the substrate plane 31a via a plurality of holding members 38. The holding members 38 connecting each of the power supply substrates 34A to 34C to the substrate plane 31a penetrate through the substrate plane 31a and reach the processing tank 1 and are in contact with the outer surface 1g of the processing tank 1. In FIG. 2, the holding members 38 connecting each of the power supply substrates 34A to 34C to the substrate plane 31a do not reach each of the power supply substrates 34A to 34C, but actually reach each of the power supply substrates 34A to 34C. Also, a part of the power supply substrate 34A and a part of the power supply substrate 34B that overlap when viewed along the vertical direction of the substrate plane 31a are connected to each other with a space therebetween via the holding member 38. Also, a part of the power supply substrate 34A and a part of the oscillation substrate 35 that overlap when viewed along the vertical direction of the substrate plane 31a are connected to each other with a space therebetween via the holding member 38.

[0025] Also, a part of the power supply board 34C and a part of the power supply board 34B that overlap when viewed along the vertical direction of the substrate plane 31a are connected to each other with a space therebetween via the holding member 38. Also, a part of the power supply board 34C and a part of the oscillation board 35 that overlap when viewed along the vertical direction of the substrate plane 31a are connected to each other with a space therebetween via the holding member 38. The plurality of substrates 33 are arranged offset from each other in the vertical direction of the substrate plane 31a via the plurality of holding members 38 and are arranged at least partially overlapping when viewed along the vertical direction of the substrate plane 31a.

[0026] Each of the power supply boards 34A to 34C has a plurality of heating elements 33a. The plurality of heating elements 33a are provided on the surface of each of the power supply boards 34A to 34C facing the processing tank 1. The plurality of heating elements 33a of each of the power supply boards 34A to 34C are preferably arranged at equal intervals in the Y-axis direction, which is the direction in which the cooling medium flows (see arrow D in FIG. 2) in the present embodiment, but they may be arranged at unequal intervals in the Y-axis direction. The heating elements 33a of each of the power supply boards 34A to 34C are connected to the water cooling pipe 36 via the heat dissipation fins 37. Although not shown, the oscillation board 35 also has a heating element. The heating element of the oscillation board 35 may also be connected to the water cooling pipe 36 via the heat dissipation fins 37. However, since the amount of heat generated by the heating element of the oscillation board 35 is less than that of the heating element 33a of the power supply board 34, it is not always necessary to connect the heating element of the oscillation board 35 to the water cooling pipe 36 via the heat dissipation fins 37.

[0027] The water-cooling pipe 36 is housed inside the power supply housing 31. A cooling medium flows inside the water-cooling pipe 36. In this embodiment, the processing liquid 7 in the processing tank 1 is used as the cooling medium, but a coolant dedicated for cooling may be used instead of the processing liquid 7. The water-cooling pipe 36 extends linearly along the Y-axis direction. The inner diameter and outer diameter of the water-cooling pipe 36 are constant over the entire length in the Y-axis direction. The arrow D in Fig. 2 indicates the direction in which the cooling medium in the water-cooling pipe 36 flows. The direction in which the cooling medium flows coincides with the Y-axis direction. The water-cooling pipe 36 is disposed between each of the power supply substrates 34A to 34C and the processing tank 1 in the X-axis direction. The water-cooling pipe 36 is disposed away from each of the power supply substrates 34A to 34C in the + direction in the X-axis direction of each of the power supply substrates 34A to 34C.

[0028] The heat-radiating fins 37 are housed inside the power supply housing 31 and contact the heat-generating elements 33a of the respective plurality of substrates 33 and the water-cooling pipe 36. The heat-radiating fins 37 radiate the heat of the heat-generating elements 33a to the cooling medium inside the water-cooling pipe 36. In this embodiment, one heat-radiating fin 37 is provided for each of the power supply substrates 34A to 34C, but one heat-radiating fin 37 may be provided so as to contact each of the plurality of power supply substrates 34A to 34C collectively. Each heat-radiating fin 37 contacts the plurality of heat-generating elements 33a and the outer peripheral surface of the water-cooling pipe 36. Although not shown, each heat-radiating fin 37 is disposed over the entire circumference of the outer periphery of the water-cooling pipe 36. Each heat-radiating fin 37 is disposed between each of the power supply substrates 34A to 34C and the processing tank 1 in the X-axis direction.

[0029] In order to make the temperature of the heat-generating element 33a of each substrate 33 uniform, it is preferable to dispose the heat-generating element 33a having a high heat-generating temperature near the water-cooling pipe 36 and dispose the heat-generating element 33a having a low heat-generating temperature far from the water-cooling pipe 36. In this embodiment, in the order of the heat-generating element 33a of the power supply substrate 34B, the heat-generating element 33a of the power supply substrate 34A, and the heat-generating element 33a of the power supply substrate 34C, the heat-generating temperature is high and the distance from the water-cooling pipe 36 is close. Also, in this embodiment, in the order of the heat-generating element 33a of the power supply substrate 34B, the heat-generating element 33a of the power supply substrate 34A, and the heat-generating element 33a of the power supply substrate 34C, the distance from the substrate plane 31a and the processing tank 1 is close.

[0030] The plurality of heat dissipation fins 37 have different dimensions according to the heat generation amount of the heat generating element 33a for each substrate 33. That is, the width dimensions of the plurality of heat dissipation fins 37 in the X-axis direction are different from each other according to the heat generation amount of the heat generating element 33a for each substrate 33. Specifically, in the present embodiment, the width dimension in the X-axis direction becomes shorter in the order of the heat dissipation fin 37 in contact with the heat generating element 33a of the power supply substrate 34B, the heat dissipation fin 37 in contact with the heat generating element 33a of the power supply substrate 34A, and the heat dissipation fin 37 in contact with the heat generating element 33a of the power supply substrate 34C.

[0031] The heat generated by the heat generating element 33a of each of the power supply substrates 34A to 34C is transmitted to each heat dissipation fin 37 in contact with each of the power supply substrates 34A to 34C. When the cooling medium flows through the water cooling pipe 36, heat exchange occurs between each heat dissipation fin 37 and the cooling medium. That is, the cooling medium absorbs the heat transmitted to each heat dissipation fin 37. Thereby, the heat generating element 33a of each of the power supply substrates 34A to 34C is cooled.

[0032] Next, the effects of the electric discharge machining apparatus 100 according to the present embodiment will be described.

[0033] In the technology disclosed in Patent Document 1, since a plurality of substrates are arranged on the same plane, the water cooling pipe becomes long, and the cooling efficiency for the heat generating element for each substrate is likely to be uneven, and the heat dissipation fins have a uniform structure. As a result, the temperature of the heat generating element for each substrate is likely to become non-uniform, and differences occur in the pulse shape of the output current waveform for each substrate due to the temperature characteristics of the heat generating element. When the electric discharge machining apparatus is a wire electric discharge machining apparatus, generally, by adjusting the current waveforms supplied from the upper and lower parts of the wire according to the consumption of the wire, the machining accuracy and the machining speed can be improved. However, when differences occur in the pulse shape of the output current waveform for each substrate, it becomes difficult to adjust the current waveform. Even in such a case, it is possible to adjust the current waveform by power supply control, but this causes a problem that the circuit configuration becomes complicated.

[0034] In this regard, in the present embodiment, as shown in FIG. 2, a plurality of substrates 33 are arranged so as to be displaced from each other in the direction perpendicular to the substrate plane 31a, so that part or all of the plurality of substrates 33 can be overlapped when viewed along the direction perpendicular to the substrate plane 31a. For this reason, compared with the technique disclosed in Patent Document 1, the length of the water-cooling pipe 36 in the direction parallel to the substrate plane 31a (Y-axis direction) is shortened, and it is less likely that the cooling efficiency to the heating elements 33a for each substrate 33 will be biased. Further, in the present embodiment, since the plurality of substrates 33 are arranged so as to be displaced from each other in the direction perpendicular to the substrate plane 31a, the distance from each substrate 33 to the water-cooling pipe 36 can be changed. Then, since the dimensions of the radiation fins 37 can be changed according to the heat generation amount of the heating elements 33a for each substrate 33 (in accordance with the distance between each substrate 33 and the water-cooling pipe 36), the radiation fins 37 do not have a uniform structure. As a result, the temperature of the heating elements 33a for each substrate 33 is likely to become uniform, and it is less likely that a difference will occur in the pulse shape of the output current waveform for each substrate 33 due to the temperature characteristics of the heating elements 33a. Further, since it is less likely that a difference will occur in the pulse shape of the output current waveform for each substrate 33, adjustment of the current waveform by power supply control becomes unnecessary, and complication of the circuit configuration can be avoided. Further, since it is less likely that a difference will occur in the pulse shape of the output current waveform for each substrate 33, the processing characteristics are also improved.

[0035] In the technique disclosed in Patent Document 1, since a plurality of substrates are arranged on the same plane, the distances from the output terminals of each substrate to the processing tank (between the electrodes) are equal, so it is difficult to adjust the impedance from each substrate to the processing tank. And in order to adjust the impedance from each substrate to the processing tank, it is necessary to unnecessarily change the length and thickness of the cable connected to each substrate or to form an adjustment electric circuit.

[0036] In this regard, in the present embodiment, since a plurality of substrates 33 are arranged so as to be displaced from each other in the direction perpendicular to the substrate plane 31a, the distance from the output terminal 33b of each substrate 33 to the processing tank 1 can be arbitrarily changed. That is, the distance between the output terminal 33b and the processing tank 1 is different for each substrate 33. Therefore, without unnecessarily changing the length and thickness of the cable or assembling an adjustment electrical circuit, the distance from the output terminal 33b of each substrate 33 to the processing tank 1 can be changed, and the impedance from each substrate 33 to the processing tank 1 can be arbitrarily adjusted. Thereby, the output current for each substrate 33 can be easily adjusted.

[0037] In the present embodiment, by electrically connecting each substrate 33 and the electrode gap 6 of the processing tank 1 via a connection conductor 2 such as a cable, the wiring length can be arbitrarily changed for each substrate 33. Therefore, the impedance (wiring impedance) from each substrate 33 to the processing tank 1 can be arbitrarily adjusted. Note that the configuration may be such that the impedance from each substrate 33 to the processing tank 1 is arbitrarily adjusted by a passive element having a known value instead of a cable. The passive element is a resistor, a capacitor, an inductor, or the like.

[0038] In the present embodiment, a part of each of the plurality of substrates 33 overlaps with another substrate 33 when viewed along the direction perpendicular to the substrate plane 31a, so that the length of the water cooling pipe 36 in the direction parallel to the substrate plane 31a (Y-axis direction) can be shortened. Therefore, the pressure loss of the cooling medium can be suppressed. And by designing the water cooling pipe 36 with less pressure loss, even when the processing liquid 7 containing minute processing chips is used as the cooling medium, clogging of the processing chips in the water cooling pipe 36 can be suppressed. Thereby, it becomes unnecessary to separately prepare a cooling liquid dedicated for cooling as the cooling medium, and the product cost can be reduced.

[0039] In the present embodiment, since the water cooling pipe 36 is linear along the Y-axis direction (one direction), the pressure loss of the cooling medium in the water cooling pipe 36 can be suppressed. Therefore, clogging of the processing chips in the water cooling pipe 36 can be further suppressed.

[0040] In this embodiment, each heating element 33a of the plurality of substrates 33 is a wide-gap semiconductor, which can suppress power loss and reduce the amount of heat generated by the heating element 33a.

[0041] Embodiment 2. Next, with reference to FIG. 3, the electric discharge machining apparatus 100A according to Embodiment 2 will be described. FIG. 3 is a plan view showing the configuration of the machining tank 1 and the power supply device 3 of the electric discharge machining apparatus 100A according to Embodiment 2. In this embodiment, the arrangement of the water cooling pipes 36 and the heat radiation fins 37 with respect to the substrate 33 and the machining tank 1 is different from that in Embodiment 1 described above. In Embodiment 2, parts overlapping with those in Embodiment 1 described above are denoted by the same reference numerals and the description thereof is omitted.

[0042] The oscillation substrate 35 is arranged away from the power supply substrate 34B in the + direction in the X-axis direction of the power supply substrate 34B located at the center in the Y-axis direction. The oscillation substrate 35 is arranged between the machining tank 1 and the power supply substrate 34B in the X-axis direction. The oscillation substrate 35 and the power supply substrates 34A and 34C are connected to the substrate plane 31a at intervals via the holding member 38. The holding member 38 that connects the oscillation substrate 35 and the power supply substrates 34A and 34C to the substrate plane 31a penetrates the substrate plane 31a and reaches the machining tank 1 and is in contact with the outer surface 1g of the machining tank 1. Also, a part of the power supply substrate 34A and a part of the oscillation substrate 35 that overlap when viewed along the vertical direction of the substrate plane 31a are connected to each other at intervals via the holding member 38. Also, a part of the power supply substrate 34A and a part of the power supply substrate 34B that overlap when viewed along the vertical direction of the substrate plane 31a are connected to each other at intervals via the holding member 38.

[0043] Also, a part of the power supply substrate 34B and a part of the power supply substrate 34C that overlap when viewed along the vertical direction of the substrate plane 31a are connected to each other with a space therebetween via the holding member 38. Also, a part of the power supply substrate 34C and a part of the oscillation substrate 35 that overlap when viewed along the vertical direction of the substrate plane 31a are connected to each other with a space therebetween via the holding member 38. The plurality of substrates 33 are arranged so as to be displaced from each other in the vertical direction of the substrate plane 31a via the plurality of holding members 38 and are arranged so as to at least partially overlap when viewed along the vertical direction of the substrate plane 31a.

[0044] The plurality of heating elements 33a are provided on the surface of each of the power supply substrates 34A to 34C that faces away from the processing tank 1. The plurality of heating elements 33a of each of the power supply substrates 34A to 34C are preferably arranged at equal intervals in the Y-axis direction, which is the direction in which the cooling medium flows (see the arrow D in FIG. 3) in the present embodiment, but may be arranged at unequal intervals in the Y-axis direction. Each heating element 33a of each of the power supply substrates 34A to 34C is connected to the water cooling pipe 36 via the heat dissipation fins 37.

[0045] The water cooling pipe 36 is arranged on the side opposite to the processing tank 1 with each substrate 33 sandwiched therebetween in the X-axis direction. The water cooling pipe 36 is arranged away from each of the power supply substrates 34A to 34C in one direction in the X-axis direction of each of the power supply substrates 34A to 34C.

[0046] In this embodiment, one heat radiating fin 37 is provided so as to be in contact with each of the plurality of power supply substrates 34A to 34C collectively, but one heat radiating fin 37 may be provided for each of the power supply substrates 34A to 34C. The heat radiating fin 37 is in contact with the plurality of heating elements 33a of each of the power supply substrates 34A to 34C and the outer peripheral surface of the water cooling pipe 36. Although not shown, the heat radiating fin 37 is arranged over the entire outer circumference of the water cooling pipe 36. The heat radiating fin 37 is arranged on the side opposite to the processing tank 1 with each substrate 33 interposed therebetween in the X-axis direction. In this embodiment, the heating elements 33a of the power supply substrate 34B, the heating elements 33a of the power supply substrate 34C, and the heating elements 33a of the power supply substrate 34A are in the order of having a higher heating temperature and a shorter distance from the water cooling pipe 36. Also, in this embodiment, the distance from the substrate plane 31a and the processing tank 1 is short in the order of the heating elements 33a of the power supply substrate 34A, the heating elements 33a of the power supply substrate 34C, and the heating elements 33a of the power supply substrate 34B.

[0047] The heat radiating fin 37 has different dimensions for each part according to the heat generation amount of the heating element 33a for each substrate 33. That is, the width dimension of the heat radiating fin 37 in the X-axis direction is different according to the heat generation amount of the heating element 33a for each substrate 33. Specifically, in this embodiment, the width dimension in the X-axis direction becomes shorter in the order of the portion of the heat radiating fin 37 that contacts the heating element 33a of the power supply substrate 34B, the portion of the heat radiating fin 37 that contacts the heating element 33a of the power supply substrate 34C, and the portion of the heat radiating fin 37 that contacts the heating element 33a of the power supply substrate 34A.

[0048] The heat generated by the heating elements 33a of each of the power supply substrates 34A to 34C is transmitted to the heat radiating fin 37 that contacts each of the power supply substrates 34A to 34C. When the cooling medium flows through the water cooling pipe 36, heat exchange is performed between the heat radiating fin 37 and the cooling medium. That is, the cooling medium absorbs the heat transmitted to the heat radiating fin 37. Thereby, the heating elements 33a of each of the power supply substrates 34A to 34C are cooled.

[0049] Next, the effects of the electric discharge machining apparatus 100A according to this embodiment will be described.

[0050] In this embodiment, as shown in FIG. 3, the water-cooling pipe 36 and the heat-radiating fins 37 are arranged on the opposite side of the processing tank 1 with each substrate 33 interposed therebetween in the X-axis direction (the direction perpendicular to the substrate plane 31a), whereby heat conduction from the heat-radiating fins 37 to the processing tank 1 can be suppressed. Therefore, the influence on the processing performance of the electric discharge machining apparatus 100A can be suppressed.

[0051] Embodiment 3. Next, with reference to FIGS. 4 and 5, the electric discharge machining apparatus 100B according to Embodiment 3 will be described. FIG. 4 is a plan view showing the configuration of the processing tank 1 and the power supply device 3 of the electric discharge machining apparatus 100B according to Embodiment 3. FIG. 5 is a side view showing the configuration of the power supply device 3 of the electric discharge machining apparatus 100B according to Embodiment 3. In this embodiment, the point that the entire plurality of substrates 33 overlap each other when viewed along the direction perpendicular to the substrate plane 31a and the point that a part of the plurality of substrates 33 are arranged in contact with a common heat-radiating fin 37 are different from those in the above-described Embodiments 1 and 2. In addition, in Embodiment 3, parts overlapping those in the above-described Embodiments 1 and 2 are denoted by the same reference numerals and the description thereof is omitted.

[0052] As shown in FIG. 4, in this embodiment, the three power supply substrates 34 and one oscillation substrate 35 are arranged side by side in the X-axis direction. Along the X-axis direction from the processing tank 1, the power supply substrate 34A, the power supply substrate 34B, the power supply substrate 34C, and the oscillation substrate 35 are arranged in this order. The entire power supply substrates 34A to 34C and the oscillation substrate 35 overlap each other when viewed along the direction perpendicular to the substrate plane 31a. The power supply substrate 34A is connected to the substrate plane 31a at intervals via a plurality of holding members 38. The holding member 38 that connects the power supply substrate 34A to the substrate plane 31a penetrates the substrate plane 31a and reaches the processing tank 1 and is in contact with the outer surface 1g of the processing tank 1. Further, the power supply substrate 34A and the power supply substrate 34B are connected to each other at intervals via a plurality of holding members 38. Further, the power supply substrate 34B and the power supply substrate 34C are connected to each other at intervals via a plurality of holding members 38. Further, the power supply substrate 34C and the oscillation substrate 35 are connected to each other at intervals via a plurality of holding members 38.

[0053] The plurality of heating elements 33a of each of the power supply substrates 34A and 34B are provided on the surface of each of the power supply substrates 34A and 34B facing away from the processing tank 1. As shown in FIG. 5, the plurality of heating elements 33a of the power supply substrate 34C are provided on the surface of the power supply substrate 34C facing the processing tank 1. The heating elements 33a of the power supply substrates 34B and 34C adjacent to each other in the X-axis direction face each other in the Z-axis direction with the water cooling pipes 36 and the heat radiating fins 37 therebetween. In FIG. 5, illustration of the connection conductor 2 connected to the power supply substrate 34B is omitted. As shown in FIG. 4, it is preferable that the plurality of heating elements 33a of each of the power supply substrates 34A to 34C are arranged at equal intervals in the Y-axis direction, which is the direction in which the cooling medium flows (see the arrow D in FIG. 4) as in the present embodiment, but they may be arranged at unequal intervals in the Y-axis direction.

[0054] The number of the water cooling pipes 36 is two in the present embodiment. The two water cooling pipes 36 are arranged apart from each other in the X-axis direction. Hereinafter, when distinguishing the two water cooling pipes 36, they are referred to as the water cooling pipe 36A and the water cooling pipe 36B. The water cooling pipe 36A is arranged between the power supply substrate 34A and the power supply substrate 34B in the X-axis direction. The water cooling pipe 36B is arranged between the power supply substrate 34B and the power supply substrate 34C in the X-axis direction.

[0055] The number of the heat radiating fins 37 is two in the present embodiment. The two heat radiating fins 37 are arranged adjacent to each other in the X-axis direction. Hereinafter, when distinguishing the two heat radiating fins 37, they are referred to as the heat radiating fin 37A and the heat radiating fin 37B. The heat radiating fin 37A is in contact with the plurality of heating elements 33a of the power supply substrate 34A and the outer peripheral surface of the water cooling pipe 36A. As shown in FIG. 5, the heat radiating fin 37A is arranged over the entire outer periphery of the water cooling pipe 36A. The heat radiating fin 37A is arranged between the power supply substrate 34A and the power supply substrate 34B in the X-axis direction. The heat radiating fin 37A is in contact with the heating elements 33a of the power supply substrate 34A, but not in contact with the heating elements 33a of the power supply substrate 34B. The heating elements 33a of the power supply substrate 34A are connected to the water cooling pipe 36A via the heat radiating fin 37A.

[0056] The heat dissipation fins 37B are in contact with the plurality of heating elements 33a of each of the power supply substrates 34B and 34C and the outer peripheral surface of the water cooling pipe 36B. That is, the heating elements 33a of a part (the power supply substrates 34B and 34C) of the plurality of substrates 33 are arranged in contact with the common heat dissipation fins 37. The heat dissipation fins 37B are arranged over the entire circumference of the outer periphery of the water cooling pipe 36B. The heat dissipation fins 37B are arranged between the power supply substrate 34B and the power supply substrate 34C in the X-axis direction. The heating elements 33a of each of the power supply substrates 34B and 34C are connected to the water cooling pipe 36B via the heat dissipation fins 37B.

[0057] As shown in FIG. 4, when the entire plurality of substrates 33 overlap each other when viewed along the vertical direction of the substrate plane 31a, it is preferable to connect the substrate 33 having the heating element 33a with a high heating temperature to the water cooling pipe 36 alone via the heat dissipation fins 37, and connect the plurality of substrates 33 having the heating elements 33a with a low heating temperature to the water cooling pipe 36 via the common heat dissipation fins 37. By doing so, it becomes easier to make the temperatures of the heating elements 33a of each substrate 33 uniform. In the present embodiment, the heating temperature of the heating element 33a of the power supply substrate 34A is higher than that of the heating element 33a of the power supply substrate 34B and the heating element 33a of the power supply substrate 34C. Therefore, in the present embodiment, the power supply substrate 34A is connected to the water cooling pipe 36A alone via the heat dissipation fins 37A, and the plurality of power supply substrates 34B and 34C are connected to the water cooling pipe 36B via the common heat dissipation fins 37B. In the present embodiment, in the order of the heating element 33a of the power supply substrate 34A, the heating element 33a of the power supply substrate 34B, and the heating element 33a of the power supply substrate 34C, the distances from the substrate plane 31a and the processing tank 1 are close.

[0058] The plurality of heat dissipation fins 37A and 37B have different structures from each other according to the heat generation amount of the heating element 33a for each substrate 33. Specifically, in the present embodiment, the heat dissipation fin 37A is in contact with only the heating element 33a of the power supply substrate 34A, and the heat dissipation fin 37B is in contact with both the heating element 33a of the power supply substrate 34B and the heating element 33a of the power supply substrate 34C.

[0059] The heat generated by the heating element 33a of the power supply board 34A is transferred to the heat dissipation fins 37A that come into contact with the heating element 33a of the power supply board 34A. When the cooling medium flows through the water cooling pipe 36A, heat exchange occurs between the heat dissipation fins 37A and the cooling medium. That is, the cooling medium absorbs the heat transferred to the heat dissipation fins 37A. As a result, the heating element 33a of the power supply board 34A is cooled. On the other hand, the heat generated by each of the power supply boards 34B and 34C is transferred to the heat dissipation fins 37B that come into contact with the heating elements 33a of the respective power supply boards 34B and 34C. When the cooling medium flows through the water cooling pipe 36B, heat exchange occurs between the heat dissipation fins 37B and the cooling medium. That is, the cooling medium absorbs the heat transferred to the heat dissipation fins 37B. As a result, the heating elements 33a of the respective power supply boards 34B and 34C are cooled.

[0060] Next, the effects of the electric discharge machining apparatus 100B according to the present embodiment will be described.

[0061] In the present embodiment, as shown in FIGS. 4 and 5, since the entireties of the plurality of substrates 33 overlap each other when viewed along the vertical direction of the substrate plane 31a, the exclusive area of the power supply device 3 in the machining tank 1 can be reduced.

[0062] In the present embodiment, as shown in FIG. 4, since the entireties of the plurality of substrates 33 overlap each other when viewed along the vertical direction of the substrate plane 31a, the length of the water cooling pipe 36 in the Y-axis direction can be shortened. For this reason, the pressure loss of the cooling medium can be suppressed. By designing the water cooling pipe 36 with less pressure loss, even when the machining liquid 7 containing minute machining chips is used as the cooling medium, clogging of the machining chips in the water cooling pipe 36 can be suppressed. As a result, it is not necessary to separately prepare a coolant dedicated for cooling as the cooling medium, and the product cost can be reduced.

[0063] In the present embodiment, as shown in FIG. 5, the heating elements 33a of some of the plurality of substrates 33 (power supply substrates 34B and 34C) face each other with the water cooling pipes 36B and the heat radiation fins 37B interposed therebetween in the Z-axis direction. As a result, the heating elements 33a of some of the plurality of substrates 33 are arranged in contact with the common heat radiation fins 37. That is, the heat radiation fins 37 can be shared by some of the plurality of substrates 33. For this reason, the number of components can be reduced and the entire power supply device 3 can be downsized. Further, since the entire power supply device 3 can be lightened by sharing the heat radiation fins 37, it becomes easier to attach the power supply device 3 also in the electric discharge machining device 100B driven by the machining tank 1 side.

[0064] In the present embodiment, as shown in FIG. 4, since the entire plurality of substrates 33 overlap each other when viewed along the direction perpendicular to the substrate plane 31a, the holding member 38 can be designed uniformly. For this reason, commonization and optimization of components can be achieved.

[0065] In the present embodiment, as shown in FIG. 4, the heating elements 33a of each of the plurality of substrates 33 (the plurality of power supply substrates 34A to 34C) are arranged at equal intervals with respect to the Y-axis direction which is the direction in which the cooling medium flows. As a result, the temperature of the heating element 33a for each substrate 33 is likely to become uniform, and it becomes difficult for a difference to occur in the pulse shape of the output current waveform for each substrate 33 due to the temperature characteristics of the heating element 33a. Further, since it becomes difficult for a difference to occur in the pulse shape of the output current waveform for each substrate 33, adjustment of the current waveform by power supply control becomes unnecessary, and complication of the circuit configuration can be avoided. Further, since it becomes difficult for a difference to occur in the pulse shape of the output current waveform for each substrate 33, the machining characteristics are also improved.

[0066] The configurations shown in the above embodiments are merely examples, and it is possible to combine them with other known techniques, it is possible to combine the embodiments with each other, and it is also possible to omit or change a part of the configuration without departing from the gist.

Explanation of Reference Numerals

[0067] 1 Machining groove, 1a Bottom wall, 1b Front wall, 1c Rear wall, 1d, 1e Side walls, 1f Inner surface, 1g Outer surface, 2 Connecting conductor, 3 Power supply device, 4 Electrode, 5 Workpiece, 6 Gap between electrodes, 7 Machining fluid, 8 Parasitic impedance, 31 Power supply housing, 31a Substrate plane, 32 Stabilized power supply, 33 Substrate, 33a Heating element, 33b Output terminal, 34, 34A, 34B, 34C Power supply substrates, 35 Oscillation substrate, 36, 36A, 36B Water cooling pipes, 37, 37A, 37B Heat dissipation fins, 38 Holding member, 100, 100A, 100B Electrical discharge machining apparatuses, D Arrow.

Claims

1. An electric discharge machining apparatus that generates an electric discharge between electrodes formed between an electrode and a workpiece, and machines the workpiece by arc heat of the electric discharge, a machining tank that accommodates the electrode and the workpiece and stores a machining liquid; A power supply device that supplies a current between the electrodes; Equipped with The power supply device is A power supply housing disposed on an outer surface of the processing tank; A plurality of substrates each having a heat generating element and housed within the power supply housing; a water-cooled pipe housed within the power supply housing and through which a cooling medium flows; a heat dissipation fin housed in the power supply housing and in contact with the heat generating elements and the water cooling pipes of each of the plurality of boards; having the power supply housing has a base surface facing an outer surface of the processing tank, The plurality of substrates are arranged to be shifted from each other in a direction perpendicular to the substrate plane, The electric discharge machining apparatus, wherein the heat dissipation fins have different structures or dimensions depending on the amount of heat generated by the heat generating elements of each of the substrates.

2. Each of the plurality of substrates has an output terminal; 2. The electric discharge machining apparatus according to claim 1, wherein a distance from the output terminal to the machining tank varies for each of the substrates.

3. 2. The electric discharge machining apparatus according to claim 1, wherein a part or the whole of each of the plurality of substrates overlaps another substrate when viewed in a direction perpendicular to the substrate plane.

4. The entirety of each of the plurality of substrates overlaps one another when viewed along a direction perpendicular to the substrate plane; Some of the heat generating elements of the plurality of substrates are disposed in contact with a common heat dissipation fin; 2. The electric discharge machining apparatus according to claim 1, wherein the heat generating elements of each of the plurality of substrates are disposed at equal intervals in a direction in which the cooling medium flows.

5. 5. The electric discharge machining apparatus according to claim 1, wherein the heat generating element of each of the plurality of substrates is a wide gap semiconductor.

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