JP2016203284A - Electrolytic discharge processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic discharge processing device that in subjecting a hard-to cut material to electrolytic discharge processing, can suppress increase in used amounts of electrolytes and decrease in processing degrees (processing efficiencies) of the hard-to cut material to supplied electricity.SOLUTION: An electrolyte discharge processing device 100 comprises: bar-like main electrodes 12 which contact a surface S of a hard-to cut material M with insulation properties; a nozzle 14 which supplies electrolytes L to the surface S of the hard-to cut material M; an auxiliary electrode 13 arranged separately relative to the main electrodes 12; an electricity supply part 17 which is arranged on the surface S of the hard-to cut material M and applies voltages between the main electrodes 12 and the auxiliary electrode 13 through the electrolytes L; and an electrolyte retaining part (the auxiliary electrode 13) which retains the electrolytes L between the main electrodes 12 and the auxiliary electrode 13.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrolytic discharge machining apparatus for machining a difficult-to-cut material having insulating properties.

  2. Description of the Related Art Conventionally, an electrolytic discharge machining apparatus that processes an insulating material is known (see, for example, Patent Document 1).

  Patent Document 1 discloses a rod-like conductive electrode (main electrode) and an auxiliary electrode that are disposed on a defective conductor workpiece whose conductivity is close to an incompletely conductive state (having insulation), and a defective conductor. Disclosed is a composite electric discharge machining apparatus including an electrolyte supply pipe that supplies an insulating liquid (electrolyte) on a workpiece, and a power source that applies a voltage between the conductive electrode and the auxiliary electrode via the electrolyte. ing. In this composite electric discharge machining apparatus, a discharge phenomenon is generated in the conductive electrode by applying a voltage. As a result, the defective conductor workpiece is subjected to electrolytic discharge machining, the surface of the defective conductor workpiece is melted, and a chemical substitution reaction occurs between the defective conductor workpiece and the electrolytic solution that has become high temperature. The defective conductor workpiece is etched.

JP 2002-172528 A

  However, the composite electric discharge machining apparatus described in Patent Document 1 has a disadvantage that the insulating liquid is supplied not only between the conductive electrode and the auxiliary electrode but also over a wide area on the surface of the defective conductor workpiece. For this reason, when electrolytic discharge machining is performed on a defective conductor workpiece, the amount of electrolyte used is increased, and current is leaked to a current path other than between the conductive electrode and the auxiliary electrode. There is a problem that the degree of machining (working efficiency) of a defective conductor workpiece is reduced. It is particularly important to improve the effectiveness of electrolytic discharge machining by eliminating the above-described problems when machining difficult-to-cut materials that are difficult to perform mechanical cutting.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to increase the amount of electrolyte used and supply it when electrolytically machining difficult-to-cut materials. It is an object of the present invention to provide an electrolytic discharge machining apparatus capable of suppressing a reduction in the degree of machining (machining efficiency) of a difficult-to-cut material with respect to electric power.

  In order to achieve the above object, an electrolytic discharge machining apparatus according to one aspect of the present invention supplies a bar-shaped main electrode that is in contact with the surface of a hard-to-cut material having insulating properties and an electrolyte to the surface of the hard-to-cut material. An electrolytic solution supply unit, an auxiliary electrode that is spaced apart from the main electrode, a power supply unit that applies a voltage between the main electrode and the auxiliary electrode via the electrolytic solution, and the surface of the difficult-to-cut material or An electrolyte solution retaining portion is disposed so as to surround the cutting material and retains the electrolyte solution between the main electrode and the auxiliary electrode. The “difficult-to-cut material” means a member that is relatively hard and difficult to cut. Further, “retaining the electrolytic solution” means that at least a part of the electrolytic solution supplied from the electrolytic solution supply unit is damped so that the electrolytic solution is located at least between the main electrode and the auxiliary electrode. .

  In the electrolytic discharge machining apparatus according to one aspect of the present invention, as described above, the electrolytic solution is disposed so as to surround the surface of the difficult-to-cut material or the difficult-to-cut material, and retains the electrolytic solution between the main electrode and the auxiliary electrode. A retention part is provided. As a result, the electrolytic solution can be retained between the main electrode and the auxiliary electrode where the electrolytic solution needs to be disposed by the electrolytic solution retaining portion, so that an electrolytic solution other than between the main electrode and the auxiliary electrode is unnecessary. It is possible to suppress unnecessary supply of the electrolytic solution to such a portion. Thereby, when carrying out the electrolytic discharge machining of the difficult-to-cut material, the increase in the usage-amount of electrolyte solution can be suppressed. In addition, since the current leaking to the portion where the electrolytic solution is unnecessary can be reduced, the degree of machining (machining efficiency) of the difficult-to-cut material with respect to the supplied power is reduced when electrolytically machining the difficult-to-cut material. Can be suppressed. Furthermore, by providing an electrolytic solution retention part that retains the electrolytic solution between the main electrode and the auxiliary electrode, not only when the main electrode is disposed vertically downward, but in the direction intersecting the vertical direction with the main electrode. It can be arranged horizontally or vertically upward. Thereby, it is possible to electrolytically discharge the difficult-to-cut material regardless of the arrangement state of the difficult-to-cut material.

  In the electrolytic discharge machining apparatus according to the above aspect, the auxiliary electrode is preferably formed in a cylindrical shape surrounding the main electrode, and also serves as an electrolytic solution retention portion. If comprised in this way, since it is not necessary to provide an electrolyte solution retention part separately from an auxiliary electrode, the increase in a number of parts and complication of a structure can be suppressed.

  In this case, preferably, a plurality of main electrodes are formed, and one auxiliary electrode also serving as an electrolyte solution retaining portion is formed in a cylindrical shape so as to surround all of the plurality of main electrodes. If comprised in this way, since an electrolyte solution can be made to stay between several main electrodes and auxiliary electrodes only with one auxiliary electrode and each current path can be formed, the number of parts increases and the structure becomes complicated Can be more effectively suppressed.

  In the electrolytic discharge machining apparatus according to the above aspect, preferably, a plurality of main electrodes are formed, and a plurality of urging members that urge each of the plurality of main electrodes independently to the surface side of the difficult-to-cut material are further provided. Prepare. If comprised in this way, since it can suppress that a main electrode separates from the surface of a difficult-to-cut material by an urging member, it originates in having separated the main electrode, and the electrolytic discharge machining of a difficult-to-cut material is carried out. It can suppress that the case where it is not performed arises. Further, by urging the plurality of main electrodes to the surface side of the difficult-to-cut material independently by the plurality of urging members, irregularities and undulations are formed on the surface of the difficult-to-cut material. Even when the height positions at which the respective surfaces abut on the surface of the difficult-to-cut material are different, it is possible to reliably suppress the plurality of main electrodes from being separated from the surface of the difficult-to-cut material.

  In the electrolytic discharge machining apparatus according to the above aspect, the electrolytic solution supplied by the electrolytic solution supply unit preferably has strong alkalinity. If comprised in this way, since the chemical reaction between an insulating difficult-to-cut material and electrolyte solution can be advanced using the heat | fever produced by electrolytic discharge machining, the process of an insulating difficult-to-cut material can be carried out. Can be promoted. Thereby, the processing degree (processing efficiency) of the difficult-to-cut material with respect to the supplied electric power can be improved effectively.

  The electrolytic discharge machining apparatus according to the one aspect described above preferably further includes a cylindrical cover portion formed so as to surround at least the main electrode and the electrolyte solution supply portion and extending to the vicinity of the surface of the difficult-to-cut material disposed in water. The gas for isolating the electrolyte staying between the main electrode and the auxiliary electrode from the water outside the cylindrical cover portion is configured to circulate in the cylindrical cover portion. If comprised in this way, since it can suppress that the electrolyte solution which retains between a main electrode and an auxiliary electrode is diluted with water, an electric current is passed between the main electrode and auxiliary electrode through an electrolyte solution. Can be prevented from flowing.

  In the electrolytic discharge machining apparatus according to the above aspect, preferably provided in the circulation path section and the circulation path section for supplying again the electrolyte flowing out from the electrolyte retention section to the surface of the difficult-to-cut material from the electrolyte supply section And a pump for circulating the electrolyte solution and a filter provided in the circulation path section for removing foreign substances in the electrolyte solution. If comprised in this way, the foreign material in the electrolyte solution flowing out from the electrolyte solution retention part can be removed by the filter and supplied again to the surface of the difficult-to-cut material from the electrolyte solution supply part. In electric discharge machining, an increase in the amount of electrolyte used can be effectively suppressed.

  In the electrolytic discharge machining apparatus according to the above aspect, preferably, a plurality of main electrodes are connected in parallel, and are respectively provided between the power supply unit and the plurality of main electrodes, and any of the plurality of main electrodes is provided. It further includes a plurality of balance resistance elements for suppressing a sudden increase in the current of the main electrode. If comprised in this way, in electrolytic discharge machining, it can suppress that an electric current concentrates and flows only to the specific main electrode of a some main electrode.

  In the electrolytic discharge machining apparatus according to the above aspect, the difficult-to-cut material is preferably fuel debris containing uranium and zirconium. By performing electrolytic discharge machining with the electrolytic discharge machining apparatus of the present invention on fuel debris made of such materials, the amount of electrolyte used increases and the degree of machining of difficult-to-cut materials with respect to the supplied power decreases. Electrolytic discharge machining that forms holes and cracks in the fuel debris can be performed in a state where the above is suppressed. Thereby, since the fuel debris containing uranium and zirconium can be crushed into smaller pieces, the fuel debris can be disposed of efficiently.

  According to the present invention, as described above, when electrolytically cutting a difficult-to-cut material, an increase in the amount of electrolyte used and a reduction in the processing degree (machining efficiency) of the difficult-to-cut material with respect to the supplied power are suppressed. can do.

1 is a schematic diagram of an electrolytic discharge machining apparatus according to a first embodiment of the present invention. It is the typical perspective view which showed the periphery of the main electrode of the electrolytic discharge machining apparatus by 1st Embodiment of this invention, and an auxiliary electrode. It is sectional drawing which showed the periphery of the main electrode and auxiliary electrode of the electrolytic discharge machining apparatus by 1st Embodiment of this invention. It is the graph which showed the relationship between the voltage and average current in electrolytic discharge machining. It is the photograph which showed the result of the electrolytic discharge machining of the Example performed in order to confirm the effect of this invention. It is a typical figure of the electrolytic discharge machining apparatus by 2nd Embodiment of this invention. It is the typical figure which showed the state which changed arrangement | positioning of the electrolytic discharge machining apparatus of 1st Embodiment of this invention. It is a typical figure of the electrolytic discharge machining apparatus by the modification of 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
With reference to FIGS. 1-3, the electrolytic discharge machining apparatus 100 by 1st Embodiment of this invention is demonstrated.

(Overall configuration of electrolytic discharge machining equipment)
As shown in FIG. 1, the electrolytic discharge machining apparatus 100 includes a main body 1 that performs electrolytic discharge machining on a difficult-to-cut material M, a reservoir 2 that stores an electrolytic solution L, and a main body 1 and a reservoir. 2 and a circulation path portion 3 composed of a pipe through which the electrolyte L circulates. The electrolytic solution L is a strong alkaline aqueous solution such as an aqueous solution of sodium hydroxide (NaOH) or an aqueous solution of potassium hydroxide (KOH), and preferably has a weight percent concentration of about 10 wt%.

The difficult-to-cut material M is relatively hard and difficult to cut, such as a material containing high-hardness ceramics such as zirconia (zirconium oxide, ZrO ₂ ) having a Vickers hardness (Hv) of about 1300. Consists of materials. For example, the difficult-to-cut material M is fuel debris containing zirconium, uranium, and oxygen.

  The electrolytic discharge machining apparatus 100 includes a pump 3 a and a filter 3 b that are disposed on the upstream side of the storage unit 2 of the circulation path unit 3, and a pump 3 c that is disposed on the downstream side of the storage unit 2 of the circulation path unit 3. It has more. The circulation path portion 3 is configured such that the electrolytic solution L in the main body portion 1 flows toward the storage portion 2 by the pump 3a. At that time, foreign matters such as impurities and debris in the electrolytic solution L generated by electrolytic discharge machining are removed by the filter 3b and flow into the storage unit 2 and stored. Thereafter, the pump 3c is configured so that the electrolytic solution L in the reservoir 2 flows toward the main body 1. As a result, the electrolyte L flowing out from an auxiliary electrode 13 (described later) in the main body 1 passes through the circulation path portion 3 and is circulated again to the surface S of the difficult-to-cut material M disposed in the main body 1. It is configured to be supplied.

<Configuration of main unit>
The main body 1 includes a cylindrical cover 10 and a seal member 11 disposed between the cover 10 and the mounting surface of the cover 10.

  The cover unit 10 has a function of suppressing the electrolytic solution L in the cover unit 10 from scattering to the outside of the main body unit 1 and a function of temporarily storing the electrolytic solution L leaking from the auxiliary electrode 13 inside. Have. Moreover, the circulation path part 3 is connected to the bottom part vicinity of the mounting surface side of the cover part 10, and the electrolyte solution L inside the cover part 10 is collect | recovered. The seal member 11 has a function of suppressing leakage of the electrolyte L inside the cover portion 10 from between the cover portion 10 and the mounting surface.

  As shown in FIG. 2, the main body 1 includes a plurality of (four) main electrodes 12, one auxiliary electrode 13 supported by the cover 10, and a nozzle 14 that supplies the electrolyte L. . The nozzle 14 is an example of the “electrolyte supply unit” in the present invention. The four main electrodes 12 are formed in substantially the same rod shape. Further, the end 12a of the main electrode 12 on the difficult-to-cut material M side is formed in a shape that tapers toward the difficult-to-cut material M side, and is in contact with the surface S of the difficult-to-cut material M.

  The main electrode 12 is made of tungsten to which thorium is added. Here, since the main electrode 12 is made of tungsten, it has heat resistance that does not melt due to heat generated in electrolytic discharge machining. The work function of the main electrode 12 is lowered by adding thorium, and as a result, electrons are easily emitted from the periphery of the tapered end portion 12a of the main electrode 12. The main electrode 12 is not limited to tungsten to which thorium is added as long as it is a conductive material that does not corrode with the electrolyte L having strong alkalinity and has sufficient heat resistance.

  Each of the four main electrodes 12 is independently attached with a spring 15 formed of a helical spring. In FIG. 2, the illustration of the spring 15 in one main electrode 12 is omitted. The four springs 15 are respectively disposed between the flange 12b and the spring fixing portion 16 in a state of being disposed between the flange 12b of the main electrode 12 and the disc-shaped spring fixing portion 16 fixed to the cover portion 10. It is fixed. Thereby, each of the four springs 15 has a function of generating an urging force independently in the vertical direction (Z direction) in which the main electrode 12 extends. The spring 15 is configured to bias the main electrode 12 toward the surface S of the difficult-to-cut material M. As a result, as shown in FIG. 3, the four main electrodes 12 are independently urged by the four springs 15 even when the surface S of the difficult-to-cut material M is uneven. Therefore, the main electrode 12 can be reliably brought into contact with the surface S of the difficult-to-cut material M in accordance with unevenness and undulations. The spring 15 is an example of the “biasing member” in the present invention.

  Here, in the first embodiment, as shown in FIG. 2, one auxiliary electrode 13 is formed in a cylindrical shape, and surrounds the difficult-to-cut material M side of the four main electrodes 12 from the X direction and the Y direction. As described above, it is disposed on the surface S of the difficult-to-cut material M. As a result, the electrolyte solution L can be retained in a region surrounded by one cylindrical auxiliary electrode 13. At this time, the amount of the electrolytic solution L retained by the cylindrical auxiliary electrode 13 is such that the end portions 12a contacting the surface S of the difficult-to-cut material M of the four main electrodes 12 are at least immersed in the electrolytic solution L, and It is more than the quantity which the electrolyte solution L can contact the electrode 13. FIG. That is, the amount of the electrolytic solution L retained by the cylindrical auxiliary electrode 13 is equal to or more than the amount that the four main electrodes 12 and the auxiliary electrode 13 can be electrically connected via the electrolytic solution L. As a result, The electrolyte L is retained between the four main electrodes 12 and the auxiliary electrode 13. The auxiliary electrode 13 is an example of the “electrolyte retention part” in the present invention.

  The auxiliary electrode 13 is made of Cu, brass or the like having a sufficiently low electric resistance. In addition, the auxiliary electrode 13 should just be an electroconductive material which does not corrode with the electrolyte solution L which has strong alkalinity. In order to reduce the power loss in the electrolytic solution L, when the auxiliary electrode 13 is disposed sufficiently close to the main electrode 12, the auxiliary electrode 13 is preferably made of a material having a certain degree of heat resistance.

  Further, as shown in FIG. 3, an annular O-ring 13a that is elastically deformable is attached to the auxiliary electrode 13 on the difficult-to-cut material M side. The O-ring 13a forms a gap between the surface S of the difficult-to-cut material M and the auxiliary electrode 13 even if the surface S of the difficult-to-cut material M is uneven. It is suppressed. This suppresses leakage of the electrolyte L from the gap between the surface S of the difficult-to-cut material M and the auxiliary electrode 13 to the outside of the auxiliary electrode 13 (the side opposite to the side where the main electrode 12 is disposed). It is possible to make the electrolytic solution L stay in the auxiliary electrode 13 more. The auxiliary electrode 13 is provided with an insulating member 13b that covers the auxiliary electrode 13 from the outside. With this insulating member 13b, it is possible to reduce the current leaking to the outside of the auxiliary electrode 13. For example, the insulating member 13b is made of vinyl tape.

  The nozzle 14 is connected to the circulation path 3 and has a function of supplying the electrolyte L to the surface S of the difficult-to-cut material M surrounded by the cylindrical auxiliary electrode 13.

  Moreover, you may comprise the four main electrodes 12, the one auxiliary electrode 13, and the nozzle 14 so that it can move on the surface S of the difficult-to-cut material M in a predetermined direction. Thereby, it is possible to automate the processing of the difficult-to-cut material M.

  Further, the main body 1 connects the power supply unit 17, the wiring 18 a that connects the positive electrode side of the power supply unit 17 and the four main electrodes 12 in parallel, and the negative electrode side of the power supply unit 17 and one auxiliary electrode 13. Wiring 18b to be connected. Thereby, the power supply unit 17 can apply a voltage of a predetermined magnitude between the four main electrodes 12 and the auxiliary electrode 13 via the wirings 18 a and 18 b and the electrolytic solution L. It is configured. The power supply unit 17 is not limited to the direct current (DC), and may supply either an alternating current (AC) or a pulse current.

  Further, four balance resistance elements 19 corresponding to each of the four main electrodes 12 are provided on the wiring 18 a between the power supply unit 17 and the four main electrodes 12. The four balance resistance elements 19 are formed on the main electrode 12 whose electric resistance has decreased due to a sudden decrease in the electric resistance of one of the four main electrodes 12 during electrolytic discharge machining. It has a function of suppressing a sudden increase in flowing current.

(Explanation of electrolytic discharge machining reaction)
Next, with reference to FIG. 1, FIG. 3, and FIG. 4, the electrolytic discharge machining in the electrolytic discharge machining apparatus 100 of 1st Embodiment is demonstrated.

In a state where the end portions 12a of the four main electrodes 12 shown in FIG. 3 are in contact with the surface S of the difficult-to-cut material M, the power source portion 17 (see FIG. 1) causes the four main electrodes 12 and one auxiliary electrode 13 to In between, a voltage is applied through the electrolyte L. At this time, as shown in FIG. 4, as the voltage is increased, the current (average current) flowing through the electrolytic solution L increases substantially proportionally, and electrolysis of the electrolytic solution L proceeds. Thereby, hydrogen gas (H ₂ ) and oxygen gas (O ₂ ) are generated around the end 12a of the main electrode 12 located in the electrolyte L (electrolytic action region).

  When the voltage is further increased, bubbles around the end 12a of the main electrode 12 located in the electrolyte L are generated so as to cover the end 12a, thereby increasing the electrical resistance in the electrolyte L, and as a result. , Almost no increase in current with respect to the increase in voltage occurs (bubble generation region). Thereafter, the voltage is further increased to increase the electrolytic strength around the end 12a of the main electrode 12 beyond the dielectric breakdown strength of the bubbles, thereby causing dielectric breakdown and discharge of the bubbles. As a result, shock waves and heat are generated by dielectric breakdown of the bubbles (discharge generation region).

The surface S of the difficult-to-cut material M is weakened by the shock wave and heat generated by the dielectric breakdown of the bubbles. Furthermore, a chemical reaction proceeds between the constituent components of the difficult-to-cut material M and the electrolyte L due to heat generated by the dielectric breakdown of the bubbles, and the generated reaction product moves to the electrolyte L side. For example, zirconia (zirconium oxide, ZrO ₂ ), which is a component of fuel debris, undergoes a chemical reaction with the electrolyte L (for example, sodium hydroxide having strong alkalinity) by heat. Thereby, zirconium hydroxide (Zr (OH) ₄ ) is generated, and the generated zirconium hydroxide moves to the electrolyte solution L side. Due to this shock wave and heat, and the chemical reaction that proceeds by the heat, a hole or a crack occurs in the surface S of the difficult-to-cut material M, or the crack progresses and the difficult-to-cut material M is crushed into smaller fragments. Processing is performed. As a result, the difficult-to-cut material M is subjected to electrolytic discharge machining. In addition, the fragments produced by electrolytic discharge machining and the generated reaction products (foreign substances) are collected by the filter 3b (see FIG. 1) of the circulation path section 3.

(Effect of 1st Embodiment)
In the first embodiment, the following effects can be obtained.

  In the first embodiment, as described above, the electrolytic solution retention portion (cylindrical auxiliary electrode) that is disposed on the surface S of the difficult-to-cut material M and retains the electrolytic solution L between the main electrode 12 and the auxiliary electrode 13. 13) is provided. Thereby, since the electrolyte solution L can be retained between the main electrode 12 and the auxiliary electrode 13 in which the electrolyte solution L needs to be disposed by the cylindrical auxiliary electrode 13, the main electrode 12 and the auxiliary electrode 13 It can suppress that the electrolyte solution L is supplied unnecessarily to the part which does not require the electrolyte solution L other than between. Thereby, when carrying out the electrolytic discharge machining of the difficult-to-cut material M, the increase in the usage-amount of the electrolyte solution L can be suppressed. Moreover, since the electric current which leaks to the part which does not require the electrolyte L can be reduced, when the difficult-to-cut material M is subjected to electrolytic discharge machining, the processing degree (machining efficiency) of the difficult-to-cut material M with respect to the supplied power is reduced. Can be suppressed.

  Moreover, in 1st Embodiment, the auxiliary electrode 13 is formed in the cylinder shape surrounding the main electrode 12, and serves as an electrolyte solution retention part. Thereby, since it is not necessary to provide the electrolytic solution retention part separately from the cylindrical auxiliary electrode 13, an increase in the number of parts and a complicated structure can be suppressed.

  In the first embodiment, one auxiliary electrode 13 is formed in a cylindrical shape so as to surround all four main electrodes 12. As a result, the current paths can be formed by retaining the electrolyte L between the four main electrodes 12 and the auxiliary electrodes 13 with only one auxiliary electrode 13, thereby increasing the number of parts and making the structure complicated. Can be more effectively suppressed.

  In the first embodiment, four springs 15 that urge the four main electrodes 12 independently to the surface S side of the difficult-to-cut material M are provided. If comprised in this way, since it can suppress that the main electrode 12 spaces apart from the surface S of the difficult-to-cut material M with the spring 15, it originates in having separated the main electrode 12, and the difficult-to-cut material M of It can suppress that the case where an electrolytic discharge machining is not performed arises. Further, the four main electrodes 12 are independently urged by the four springs 15 toward the surface S of the difficult-to-cut material M, whereby irregularities and undulations are formed on the surface S of the difficult-to-cut material M. Even when the height positions at which the main electrodes 12 contact the surface S of the difficult-to-cut material M are different, it is ensured that each of the four main electrodes 12 is separated from the surface S of the difficult-to-cut material M. Can be suppressed.

  In the first embodiment, since the electrolytic solution L supplied from the nozzle 14 has strong alkalinity, the heat generated by electrolytic discharge machining is used between the insulating difficult-to-cut material M and the electrolytic solution L. Therefore, it is possible to promote the processing of the insulating difficult-to-cut material M. Thereby, the processing degree of the difficult-to-cut material M with respect to the supplied electric power can be improved effectively.

  Further, in the first embodiment, the circulation path portion 3 for supplying the electrolyte L flowing out from the cylindrical auxiliary electrode 13 to the surface S of the difficult-to-cut material M from the nozzle 14 is provided. Pumps 3a and 3c for circulating the electrolytic solution L and a filter 3b for removing foreign matter in the electrolytic solution L are provided. As a result, foreign matter in the electrolyte L flowing out of the cylindrical auxiliary electrode 13 can be removed by the filter 3b and supplied from the nozzle 14 to the surface S of the difficult-to-cut material M. When performing electric discharge machining, an increase in the amount of electrolyte L used can be effectively suppressed.

  In the first embodiment, the current of one of the plurality of main electrodes 12 suddenly increases between the four main electrodes 12 connected in parallel to the power supply unit 17. Four balance resistance elements 19 for suppression are provided. Thereby, it can suppress that an electric current concentrates and flows only to the specific main electrode 12 of the four main electrodes 12 in electrolytic discharge machining.

  In the first embodiment, the difficult-to-cut material M is preferably fuel debris containing uranium and zirconium. By performing electrolytic discharge machining on the fuel debris made of such a material by the electrolytic discharge machining apparatus 100 of the first embodiment, the amount of the electrolyte L used is increased and the difficult-to-cut material M is machined against the supplied power. Electrolytic discharge machining can be performed such that holes and cracks are formed in the fuel debris in a state where the degree is suppressed. Thereby, since the fuel debris containing uranium and zirconium can be crushed into smaller pieces, the fuel debris can be disposed of efficiently.

[Example]
Next, with reference to FIG. 2 and FIG. 5, the result of the electrolytic discharge machining performed using the electrolytic discharge machining apparatus 100 according to the first embodiment will be described as an example. Here, in the examples, as the difficult-to-cut material M, disc-shaped zirconia (ZrO ₂ ) having a Vickers hardness (Hv) of about 1300 was used. The disk-shaped zirconia had a diameter of 36 mm and a thickness of 12 mm. Further, 10 wt% sodium hydroxide was used as the electrolytic solution L.

  And the cylindrical auxiliary electrode 13 (refer FIG. 2) was arrange | positioned so that the disk-shaped difficult-to-cut material M might be surrounded. That is, the disc-shaped difficult-to-cut material M was fitted inside the cylindrical auxiliary electrode 13. Then, as shown in FIG. 2, the four main electrodes 12 were brought into contact with the surface S of the disk-shaped difficult-to-cut material M. At this time, an urging force of 5 gf (= 0.049 N) was applied to each of the four main electrodes 12 by the spring 15. The urging force was applied in the direction toward the surface S of the disk-shaped difficult-to-cut material M. Then, a voltage of 200 V was applied by the power supply unit 17 while supplying 10 wt% sodium hydroxide from the nozzle 14.

  As an experimental result, by applying a voltage of 200 V for about 10 seconds, as shown in FIG. 5, in the disk-shaped difficult-to-cut material M, the outer surface starts from the position where the four main electrodes 12 are in contact. And a crack connecting the positions where the four main electrodes 12 were in contact with each other occurred. Thus, it was confirmed that by using the electrolytic discharge machining apparatus 100 according to the first embodiment, it is possible to crush even a high hardness zirconia into a plurality of pieces.

[Second Embodiment]
Next, an electrolytic discharge machining apparatus 200 according to a second embodiment of the present invention will be described with reference to FIG. In the electrolytic discharge machining apparatus 200, unlike the first embodiment, a case where the difficult-to-cut material M arranged in water is subjected to electrolytic discharge machining will be described. In addition, the same structure as the said 1st Embodiment attaches | subjects and shows the same code | symbol as 1st Embodiment, and abbreviate | omits description.

(Configuration of electrolytic discharge machining equipment)
The electrolytic discharge machining apparatus 200 according to the second embodiment is an apparatus for electrolytic discharge machining the difficult-to-cut material M disposed in water. Here, when the difficult-to-cut material M is fuel debris containing a radioactive substance such as uranium, radiation from the fuel debris is released to the outside by water by performing electrolytic discharge machining in a state of being disposed in water. The fuel debris can be crushed while suppressing this.

  As shown in FIG. 6, the main body 101 on which the electrolytic discharge machining of the electrolytic discharge machining apparatus 200 is performed surrounds a plurality of (two) main electrodes 12, one auxiliary electrode 113, and the main electrode 12. A plurality (two) of cylindrical electrolyte supply parts 114 arranged, a plurality of (two) cylindrical electrolytes arranged so as to surround one main electrode 12 and one electrolyte supply part 114, respectively. The cover part 110 is included.

  One auxiliary electrode 113 is formed in a cylindrical shape so as to surround the end portion 12a on the difficult-to-cut material M side of the plurality (two) of main electrodes 12, and is disposed on the surface S of the difficult-to-cut material M. ing. Further, the auxiliary electrode 113 is a cylindrical auxiliary electrode in the vicinity of the main electrode 12 so that a current path can be formed with each of the plurality of main electrodes 12 via the electrolytic solution L supplied by the electrolytic solution supply unit 114. It arrange | positions so that at least one part of 113 may be located.

  Each of the plurality (two) of cylindrical electrolyte supply units 114 is configured such that the main electrode 12 is disposed inside and the electrolyte L can flow inside. In addition, the electrolyte solution L is supplied to each of the some cylindrical electrolyte solution supply part 114 from the storage part which is not shown in figure. Moreover, the cylindrical electrolyte supply part 114 is arrange | positioned so that it may extend from the upper side (Z1 side) to the surface S vicinity of the difficult-to-cut material M from the water surface. Thereby, since it can suppress that the electrolyte solution L contacts with water, it is possible to suppress that the electrolyte solution L is diluted with water. The electrolyte supply unit 114 is made of an insulator.

  The plurality of (two) cylindrical cover portions 110 are arranged so as to extend from above the water surface to the vicinity of the surface S of the difficult-to-cut material M, similarly to the electrolyte solution supply portion 114. Further, an inert gas such as nitrogen gas is configured to flow toward the surface S of the difficult-to-cut material M inside the cylindrical cover portion 110 and outside the electrolyte solution supply portion 114. As a result, the electrolytic solution L supplied between the main electrode 12 and the auxiliary electrode 113 from the electrolytic solution supply unit 114 can be retained inside the air flow, and the electrolytic solution L and the cover are provided in the vicinity of the auxiliary electrode 113. It is possible to effectively suppress contact with water outside the portion 110. The inert gas is discharged as bubbles in the water from the gap between the surface S of the difficult-to-cut material M and the cover part 110. Moreover, the other structure of the main-body part 101 of the electrolytic discharge machining apparatus 200 is the same as that of the said 1st Embodiment.

  Moreover, regarding the electrolytic discharge machining in the electrolytic discharge machining apparatus 200 according to the second embodiment, the inert gas is circulated toward the surface S of the difficult-to-cut material M arranged in water, and the first embodiment described above. The electrolytic discharge machining is performed in the same manner as the electrolytic discharge machining.

(Effect of 2nd Embodiment)
In the second embodiment, the following effects can be obtained.

  In the second embodiment, as described above, the electrolytic solution retention portion (cylindrical auxiliary electrode) that is disposed on the surface S of the difficult-to-cut material M and retains the electrolytic solution L between the main electrode 12 and the auxiliary electrode 113. 113). As a result, as in the first embodiment, when electrolytically cutting the difficult-to-cut material M, an increase in the amount of the electrolyte L used can be suppressed, and the machining of the difficult-to-cut material M with respect to the supplied power can be performed. It is possible to suppress the degree from decreasing.

  Moreover, in 2nd Embodiment, the cylindrical cover part 110 extended to the surface S vicinity of the difficult-to-cut material M arrange | positioned in water is provided so that the main electrode 12 and the electrolyte solution supply part 114 may be surrounded. In addition, an inert gas for isolating the electrolytic solution L staying between the main electrode 12 and the auxiliary electrode 113 from the water outside the cylindrical cover portion 110 flows in the cylindrical cover portion 110. Configure. Thereby, since it can suppress that the electrolyte solution L which retains between the main electrode 12 and the auxiliary electrode 113 is diluted with water, between the main electrode 12 and the auxiliary electrode 113 through the electrolyte solution L It is possible to suppress the current from becoming difficult to flow. The remaining effects of the second embodiment are similar to those of the aforementioned first embodiment.

  The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments and examples but by the scope of claims for patent, and includes all modifications (modifications) within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the electrolytic discharge machining apparatus 100 of the first embodiment and the electrolytic discharge machining apparatus 200 of the second embodiment, the example in which the main electrode 12 is brought into contact with the surface S of the difficult-to-cut material M downward from above is shown. In the electrolytic discharge machining apparatus 100 of the first embodiment and the electrolytic discharge machining apparatus 200 of the second embodiment, the main electrode 12 and the auxiliary electrode 13 (113) are separated by the electrolytic solution retention portion (auxiliary electrode 13 (113)). Since the electrolytic solution L can be retained between the main electrodes 12, the main electrode 12 is disposed horizontally in a direction intersecting the vertical direction (for example, a horizontal direction orthogonal to the vertical direction) or disposed upward in the vertical direction. It is possible to Thereby, irrespective of the arrangement | positioning condition of the difficult-to-cut material M, it is possible to carry out the electrolytic discharge machining of the difficult-to-cut material M. For example, the electrolytic discharge machining apparatus 100 of FIG. 1 is arranged so that the main electrode 12 is horizontally oriented as shown in FIG. It is possible to perform electrolytic discharge machining in a state in which the horizontal main electrode 12 is in contact with the surface S extending in the direction (Z direction). In addition, when arrange | positioning the electrolytic discharge machining apparatus 100 like FIG. 7, it is preferable to newly provide the mechanism which presses the cover part 10 and the auxiliary electrode 13 to a horizontal direction.

  Further, in the first and second embodiments, the one electrolyte electrode L can be retained between the plurality of main electrodes 12 and the auxiliary electrodes 13 (113) in one auxiliary electrode 13 (113). Although the example which formed is shown, this invention is not limited to this. In this invention, you may provide the electrolyte solution retention part which can make electrolyte solution retain between a main electrode and an auxiliary electrode separately from an auxiliary electrode.

  In the first and second embodiments, examples using four and two main electrodes 12 are shown, but the present invention is not limited to this. In the present invention, three or five or more main electrodes may be used, or one main electrode may be used.

  In the first and second embodiments, an example in which one auxiliary electrode 13 is used has been described. However, the present invention is not limited to this. In the present invention, a plurality of auxiliary electrodes may be used. At this time, an auxiliary electrode may be provided for each of the plurality of main electrodes, or one auxiliary electrode common to several main electrodes may be provided.

  Moreover, in the said 1st and 2nd embodiment, although the material containing high-hardness ceramics, such as a zirconia, was shown as an example as the difficult-to-cut material M, this invention is not limited to this. In the present invention, the difficult-to-cut material M may be concrete that is insulative and hard to some extent. In addition, the electrolytic discharge machining apparatus of the present invention is particularly suitable for processing (crushing) difficult-to-cut materials having complicated shapes that are difficult to break by machining, or difficult-to-cut materials with extremely high hardness.

Moreover, in the said 1st and 2nd embodiment, although the example using the aqueous solution which has strong alkalinity as the electrolyte solution L was shown, this invention is not limited to this. In the present invention, a solution having conductivity other than strong alkalinity may be used as the electrolytic solution. For example, an ionic aqueous solution such as an aqueous solution of sodium chloride (NaCl) or an aqueous solution of sodium nitrate (NaNO ₃ ) may be used. In addition, when using a material that does not easily cause a chemical reaction with a strong alkaline solution such as concrete as a difficult-to-cut material, a strong alkaline property having high reactivity can be obtained by using an aqueous ionic solution such as a sodium chloride aqueous solution or a sodium nitrate aqueous solution. It is possible to perform electrolytic discharge machining more safely than in the case of using the aqueous solution. Even in this case, the surface of the concrete can be vitrified and made brittle by impact force or heat based on dielectric breakdown of bubbles generated in electrolytic discharge machining.

  In the first and second embodiments, the example in which the plurality of springs 15 that urge the plurality of main electrodes 12 independently toward the surface S of the difficult-to-cut material M is provided has been described. Is not limited to this. In this invention, you may comprise so that several main electrodes may be urged | biased by one spring, and you may urge a main electrode toward the surface of a difficult-to-cut material by elastic members other than a spring. Moreover, you may comprise so that a main electrode may be pressed toward the surface of a difficult-to-cut material with the dead weight of a main electrode, without providing a spring.

  In the second embodiment, an example in which a plurality of (two) cylindrical cover portions 110 are disposed so as to surround one main electrode 12 and one electrolyte supply portion 114 has been described. The invention is not limited to this. For example, as in the electrolytic discharge machining apparatus 300 according to the modification of the second embodiment shown in FIG. 8, the cylindrical cover portion 210 is 1 so as to surround the two main electrodes 12 and the two electrolyte supply portions 114. You may arrange only one. Thereby, it is possible to further suppress the increase in the number of parts and the complexity of the structure. In the configuration of the modified example of the second embodiment, only one electrolyte supply unit may be arranged so as to surround both of the two main electrodes. Thereby, it is possible to further effectively suppress the increase in the number of parts and the complexity of the structure.

  In the first and second embodiments, the example in which the balance resistor 19 is disposed between each of the plurality of main electrodes 12 and the power supply unit 17 has been described. However, the present invention is not limited to this. In the present invention, the balance resistor may not be arranged. In particular, when there is one main electrode, there is no need to provide a balance resistor. Alternatively, the power to each of the plurality of main electrodes may be adjusted by separately forming current paths corresponding to each of the plurality of main electrodes without providing a balance resistor.

  In the first and second embodiments, the positive electrode side of the power supply unit 17 and the main electrode 12 are connected, and the negative electrode side of the power supply unit 17 and the auxiliary electrode 13 (113) are connected. The present invention is not limited to this. In the present invention, the negative electrode side of the power supply unit and the main electrode may be connected, and the positive electrode side of the power supply unit and the auxiliary electrode may be connected. Further, the power supply unit is not limited to direct current, and the same effect can be obtained even with a power supply that is generated in an alternating current or pulse form.

  Moreover, although the example which has arrange | positioned the auxiliary electrode 13 (113) in the surface S of the difficult-to-cut material M was shown in the said 1st and 2nd embodiment, this invention is not limited to this. In this invention, as demonstrated in the Example, you may arrange | position an auxiliary electrode so that a difficult-to-cut material may be surrounded.

  Moreover, in the said 2nd Embodiment, although the example in which the inert gas which distribute | circulates the inside of the cover part 110 was discharged | emitted in water was shown, this invention is not limited to this. In this invention, you may comprise so that an inert gas and electrolyte solution may be sucked and collect | recovered using the suction tube extended from the outer side of water to the auxiliary electrode vicinity.

DESCRIPTION OF SYMBOLS 3 Circulation path part 3a, 3c Pump 3b Filter 12 Main electrode 13, 113 Auxiliary electrode 14 Nozzle (electrolyte supply part)
15 Spring (biasing member)
17 Power source part 19 Balance resistance element 100, 200, 300 Electrolytic discharge machining apparatus 110, 210 Cover part 114 Electrolyte supply part L Electrolytic solution M Difficult-to-cut material S (of difficult-to-cut material) surface

Claims (9)

A rod-shaped main electrode that contacts the surface of a hard-to-cut material having insulating properties;
An electrolyte supply unit for supplying an electrolyte to the surface of the difficult-to-cut material;
An auxiliary electrode spaced apart from the main electrode;
A power supply for applying a voltage between the main electrode and the auxiliary electrode via the electrolyte;
An electrolytic discharge machining apparatus comprising an electrolyte solution retaining portion that is disposed so as to surround the surface of the difficult-to-cut material or the difficult-to-cut material, and retains the electrolyte solution between the main electrode and the auxiliary electrode.   2. The electrolytic discharge machining apparatus according to claim 1, wherein the auxiliary electrode is formed in a cylindrical shape surrounding the main electrode and serves also as the electrolytic solution retention portion. A plurality of the main electrodes are formed,
3. The electrolytic discharge machining apparatus according to claim 2, wherein the one auxiliary electrode serving also as the electrolyte solution retention portion is formed in a cylindrical shape so as to surround all of the plurality of main electrodes. A plurality of the main electrodes are formed,
The electrolytic discharge machining apparatus according to claim 1, further comprising a plurality of biasing members that independently bias the plurality of main electrodes toward the surface side of the difficult-to-cut material.   The electrolytic solution machining apparatus according to any one of claims 1 to 4, wherein the electrolytic solution supplied by the electrolytic solution supply unit has strong alkalinity. A cylindrical cover portion formed so as to surround at least the main electrode and the electrolyte solution supply portion, and extending to the vicinity of the surface of the difficult-to-cut material disposed in water;
A gas for isolating the electrolytic solution staying between the main electrode and the auxiliary electrode from the water outside the cylindrical cover portion is configured to circulate in the cylindrical cover portion. The electrolytic discharge machining apparatus according to any one of claims 1 to 5. A circulation path section for causing the electrolyte solution flowing out from the electrolyte solution retention section to be supplied again from the electrolyte solution supply section to the surface of the difficult-to-cut material;
A pump provided in the circulation path section for circulating the electrolyte;
The electrolytic discharge machining apparatus according to claim 1, further comprising a filter that is provided in the circulation path portion and removes foreign matters in the electrolytic solution. A plurality of the main electrodes are connected in parallel,
A plurality of balance resistance elements provided between the power supply unit and the plurality of main electrodes, respectively, for suppressing a sudden increase in the current of any of the plurality of main electrodes. The electrolytic discharge machining apparatus according to claim 1, further comprising:   The electrolytic discharge machining apparatus according to claim 1, wherein the difficult-to-cut material is fuel debris containing uranium and zirconium.