Discharge coating device and discharge coating method

Abstract

To provide a discharge coating device and a discharge coating method for densely performing a discharge coating of a metal or a conductive metal compound.SOLUTION: A discharge coating device has: an electrode in a half-sintered state where a powder of a metal or a conductive metal workpiece is molded by compression molding and then heated at a temperature lower than a sintering temperature; a power source that applies a voltage between the electrode and a workpiece and generates a discharge in a transit time of contact and release between the electrode and the workpiece; an electrode driving device that makes a relative transit state between poles of the electrode and the workpiece manually or mechanically, and repeats contact and release; and an inert gas supply device that supplies an inert gas for preventing an oxidation between the poles, wherein an electrode material molten by a discharge generated between the poles of the electrode and the workpiece is attached onto the workpiece.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electrical discharge coating technology in which, in an inert gas atmosphere such as argon, a voltage is applied between an electrode rod and a workpiece, and contact and release are repeated. The discharge generated during this process causes the melted electrode material to adhere to the surface of the workpiece, thereby coating or building up the workpiece. [Background technology]

[0002] Techniques for coating or depositing electrode materials such as metals and metal carbides onto the surfaces of workpieces such as dies and machine parts by utilizing the high temperatures generated by discharge in an air atmosphere include, for example, Patent No. 2939083, "Method for deposit repair of metal members, metal members repaired by said repair method, and repair device," Patent No. 3347450, "Discharge-type coating device," and Patent No. 5822218 (disclosed as Patent Document 1, Patent Document 2, and Patent Document 3, respectively).

[0003] More specifically, Patent Document 1 discloses a metal component build-up repair method that uses electrical discharge coating to build up worn or missing parts on the surface of the metal component (workpiece) to be repaired, as well as technology related to a metal component repaired by this repair method and a repair device.In particular, it discloses a metal component build-up repair method that allows the workpiece to be repaired by build-up while it is attached without having to be removed from the device, significantly reducing the effort and cost of repair, as well as the provision of a metal component repaired by this repair method and a repair device.

[0004] Patent Document 2 relates to an electric discharge coating device in which an electrode rod is brought close to the surface of a metal workpiece to be repaired and electrode rod material is vapor-deposited onto the surface to be repaired by spark discharge generated between the two. In particular, it discloses the provision of an electric discharge coating device in which high voltage is not applied to the electrode rod while the electric discharge coating work is interrupted, and the applied voltage during the electric discharge coating work can be increased to improve work efficiency.

[0005] Patent Document 3 discloses a technology relating to an improved discharge coating method and discharge coating device for repairing or modifying worn or missing parts on the surface of a conductive workpiece or modifying the surface of the conductive workpiece by discharge coating, and is particularly characterized by effectively reducing the occurrence of defects at the beginning or restart of discharge coating work and improving the uniformity of the coating.

[0006] All of these techniques involve covering or building up an electrode material in an inert gas shielding atmosphere to repair workpieces such as dies and machine parts. Typically, metal electrodes such as steel or nickel alloys can be used for build-up repairs, while electrodes whose main component is a metal carbide, such as cemented carbide (a sintered body of tungsten carbide and cobalt binder), can be used to create a thin coating. While metal carbide-based coatings adhere only to a small amount of material to the workpiece surface, they are known to be effective in preventing melting damage to die-casting dies, for example, and are used to extend the life of new dies and repair damaged dies.

[0007] On the other hand, there is also demand for cladding made of hard materials primarily composed of metal carbides, for applications such as inserting hard materials into areas of molds and machine parts that are subject to heavy loads. However, conventional electrical discharge coating technology has not been able to build up hard materials, such as cemented carbide. When coating cemented carbide with conventional electrical discharge coating, an electrode rod made of cemented carbide is used as the electrode, and an electrical discharge is generated between the electrode rod and the workpiece, causing the cemented carbide electrode material to adhere.

[0008] Figure 7 shows examples of discharge craters formed on the surface of a steel material using a cemented carbide electrode rod. These are elemental mapping images of the same field of view as the scanning electron microscope (SEM) photograph (top photo) of material deposited by a single discharge, and show the results of mapping Fe (iron), Co (cobalt), and W (tungsten), respectively. The processing conditions for all were a current value of approximately 60 A and a pulse width of approximately 130 μs. Fe (iron) is a component of the steel material that is the workpiece, and Co (cobalt) and W (tungsten) are components of the cemented carbide that is the electrode.

[0009] Figure 8 shows a photograph in which the discharge crater area in the photograph in Figure 7 has been circled. Looking at Figure 8, we can see that there are three or four points in the W mapping image that appear to be dark in the raised areas of the discharge crater in the SEM photograph (a point slightly above the center of the discharge crater and the area to the lower right of the discharge crater). The corresponding areas in the Co mapping image also appear to be dark in color, but even when looking at the Co mapping image alone, there does not appear to be any particular difference from the other areas (background noise). That is, under the conditions shown in Figure 7, the size of the discharge mark is about 400 μm in diameter, and although the steel in that area is melted, the electrode materials, tungsten carbide (WC) and Co (cobalt), if any, are attached, but are limited to a very small area.

[0010] The reason for this is that the cemented carbide (particularly the main component tungsten carbide (WC)) that is the electrode material has a higher melting point and is more difficult to melt than the steel material that is the workpiece. In other words, the heat generated by the discharge is used to melt the workpiece rather than to melt the electrode material, and the electrode material cannot be efficiently transferred to the workpiece surface. In fact, when coating cemented carbide using conventional methods, at best only a small amount of material is transferred to the workpiece surface, and a dense coating is not achieved, resulting in a sparsely distributed material on the surface. Nevertheless, even though this is an inefficient deposition method, it is still effective to some extent and has been used in the past.

[0011] However, as demands for further extension of the lifespan and improvement of performance of molds and machine parts increase, there is a growing demand for technology that can adhere hard materials such as cemented carbide and cermet more densely and thickly. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 6-269936 (Patent No. 2939083) [Patent Document 2] Japanese Patent Application Publication No. 7-228979 (Patent No. 3347450) [Patent Document 3] JP 2016-84525 A (Patent No. 5822218) Summary of the Invention [Problem to be solved by the invention]

[0013] As described above, in the prior art, even if an attempt was made to coat a workpiece with a hard material such as cemented carbide or cermet by electrical discharge coating, the hard material could only be deposited in a patchy manner, and it was not possible to coat the workpiece surface neatly or to build up a thick layer. Therefore, an object of the present invention is to solve this problem and realize a technology for adhering hard materials to molds and machine parts more densely and thickly. [Means for solving the problem]

[0014] The present invention has been completed in view of the above circumstances, and provides the optimal discharge coating apparatus described in (Claim 1) to (Claim 10) below, and the discharge coating method described in (Claim 11) to (Claim 21).

[0015] (Claim 1) A semi-sintered electrode obtained by compressing and molding powder of a metal or conductive metal workpiece and then heating it at a temperature below the sintering temperature; a power supply device that applies a voltage between the electrode and the workpiece and generates a discharge during a transition period between contact and release between the electrode and the workpiece; an electrode drive device that manually or mechanically creates a relative movement state between the electrode and the workpiece, repeatedly contacting and releasing the electrode; an inert gas supply device for supplying an inert gas for preventing oxidation between the electrodes; An electrical discharge coating device is used to deposit the electrode material melted by electrical discharge generated between the electrode and the workpiece onto the workpiece. (Claim 2) 2. The discharge coating apparatus according to claim 1, wherein the surface of the electrode is coated with a conductive material or an insulating material. (Claim 3) 3. The electrical discharge coating apparatus according to claim 2, wherein the coating material is cyanoacrylate. (Claim 4) 2. The electrical discharge coating apparatus according to claim 1, wherein the material of the electrode is mainly composed of a metal carbide and a metal binder. (Claim 5) 5. The electrical discharge coating apparatus according to claim 4, wherein the volume ratio of the metal serving as the binder in the material of the electrode is 17% or more. (Claim 6) A semi-sintered electrode obtained by compressing and molding powder of a metal or conductive metal workpiece and then heating it at a temperature below the sintering temperature; a power supply device that applies a voltage between the electrode and the workpiece and generates a discharge during a transition period between contact and release between the electrode and the workpiece; an electrode drive device that manually or mechanically creates a relative movement state between the electrode and the workpiece, repeatedly contacting and releasing the electrode; an inert gas supply device for supplying an inert gas for preventing oxidation between the electrodes; The electrode material is melted by an electric discharge generated between the electrode and the workpiece, and the melted electrode material is deposited on the workpiece. An electrical discharge coating apparatus having an energy beam irradiation device that melts the electrode material adhered to the workpiece. (Claim 7) 7. The electrical discharge coating apparatus according to claim 6, wherein the surface of the electrode is coated with a conductive material or an insulating material. (Claim 8) 8. The electrical discharge coating apparatus according to claim 7, wherein the coating material is cyanoacrylate. (Claim 9) 7. The electrical discharge coating apparatus according to claim 6, wherein the material of the electrode is mainly composed of a metal carbide and a metal binder. (Claim 10) 10. The electrical discharge coating apparatus according to claim 9, wherein the volume ratio of the metal serving as the binder in the material of the electrode is 17% or more. (Claim 11) This is an electrical discharge coating method in which a semi-sintered electrode is formed by compressing powder of a metal or conductive metal workpiece and then heating it to a temperature below the sintering temperature, and an inert gas is supplied between the workpiece and the electrode to prevent oxidation. While a voltage is applied, a state of relative movement is created between the electrode and the workpiece manually or mechanically, and contact and release are repeated, generating an electrical discharge during the transition period between contact and release, and the electrode material melted by the generated electrical discharge is deposited on the surface of the workpiece. (Claim 12) 12. The electrical discharge coating method according to claim 11, wherein the surface of the electrode is coated with a conductive material or an insulating material. (Claim 13) 13. The electrical discharge coating method according to claim 12, wherein the coating material is a cyanoacrylate. (Claim 14) 12. The electrical discharge coating method according to claim 11, wherein the material of the electrode is mainly composed of a metal carbide and a metal binder. (Claim 15) 15. The electrical discharge coating method according to claim 14, wherein the volume ratio of the metal as a binder in the material of the electrode is 17% or more. (Claim 16) A semi-sintered electrode is formed by compressing powder of a metal or conductive metal workpiece and then heating it to a temperature below the temperature at which sintering occurs, and an inert gas is supplied between the workpiece and the electrode to prevent oxidation. While a voltage is applied, a state of relative movement is created between the electrode and the workpiece manually or mechanically, and contact and release are repeated, generating an electric discharge during the transition period between contact and release, causing the electrode material to melt and adhere to the surface of the workpiece. The discharge coating method involves irradiating the workpiece with an energy beam that melts the electrode material adhered to the workpiece. (Claim 17) 17. The electrical discharge coating method according to claim 16, wherein the surface of the electrode is coated with a conductive material or an insulating material. (Claim 18) 18. The electrical discharge coating method according to claim 17, wherein the coating material is a cyanoacrylate. (Claim 19) 17. The electrical discharge coating method according to claim 16, wherein the material of the electrode is mainly composed of a metal carbide and a metal binder. (Claim 20) 20. The electrical discharge coating method according to claim 19, wherein the volume ratio of the metal as a binder in the material of the electrode is 17% or more. (Claim 21) 21. The electrical discharge coating method according to claim 16, wherein the step of adhering the electrode material melted by electrical discharge to the surface of the workpiece and the step of irradiating the workpiece with an energy beam to melt the electrode material adhered to the workpiece are repeated. [Effects of the Invention]

[0016] According to the present invention, a hard material can be densely and thickly adhered to a mold or machine part, thereby realizing repair and extending the life of the mold or machine part. BEST MODE FOR CARRYING OUT THE INVENTION

[0017] Preferred embodiments of the decorative article of the present invention will be described below with reference to Figs. 1 to 6, but the embodiments permitted by the present invention are not limited to these in any way. (Embodiment 1) An explanatory diagram of a first embodiment of the present invention is shown in Figure 1. In Figure 1, 101 denotes an electrode, 102 denotes an electrode holder, 103 denotes an inert gas injection nozzle that injects and supplies inert gas to the discharge point at the tip of the electrode, 104 denotes the inert gas injected from the inert gas injection nozzle 103, 105 denotes a workpiece, 106 denotes a power supply device that applies a voltage between the electrode 101 and the workpiece 105 to generate a discharge, and 107 denotes a discharge generated between the electrode 101 and the workpiece 105. The electrode 101 is held by an electrode holder 102 and rotated by a rotating device (not shown). It may be connected to a vibrating device instead of the rotating device. The rotating device and vibrating device are insulated from the electrode 101 and electrode holder 102, and the electrode holder is powered by a power supply 106 via a power supply part such as a brush (not shown). The other pole of the power supply 106 is connected to the workpiece 105. The inert gas injection nozzle 103 is a nozzle that injects an inert gas such as Ar (argon) gas toward the point where discharge occurs when the tip of the electrode 101 is released from contact with the workpiece 105. In Fig. 1, it is installed to the side of the electrode, but it may of course be installed coaxially with the electrode.

[0018] Next, the operation and function of the device in FIG. 1 will be described. The electrode 101 and electrode holder 102 are attached to an apparatus main body (not shown) and rotated by a rotating device attached to the apparatus main body. The apparatus main body is held by hand or by a mechanical device such as a robot, and the tip of the electrode 101 is placed against the portion of the workpiece 105 to be electrodischarge coated. When the electrode 101 is rotated while applying voltage from a power supply 106, the electrode 101 and the workpiece 105 rub against each other due to the relative speed, repeatedly short-circuiting (contact state) and opening, generating a discharge (107) at the timing between these states. The power supply 106 may be a known power supply such as those described in the above-mentioned patent documents, as long as it is equipped with a DC power supply and a switching element so that a pulsed discharge can be generated when a discharge occurs. Alternatively, a power supply having a DC power supply with a current-limiting resistor and a switching element arranged in series is also acceptable. In any case, it is preferable to be able to adjust discharge conditions such as current value and pulse width by controlling the voltage value of the power supply, the capacitor that stores the charge, and the control method of the switching element. When a discharge occurs, the heat melts the electrode at the discharge point, allowing it to adhere to the workpiece. In this embodiment, the device for driving the electrode 101 and the electrode holder 102 is a rotating device, but as long as it can impart relative movement to the electrode 101 and the workpiece 105, a vibrating device may be used instead of a rotating device.

[0019] The electrode 101 is a semi-sintered electrode that is obtained by compressing and molding powder of a metal or conductive metal workpiece and then heating it at a temperature below the sintering temperature. As a specific example, Figure 2 shows a scanning electron microscope (SEM) photograph of an electrode made by compressing a mixture of approximately 70% tungsten carbide (WC) powder and approximately 30% cobalt (Co) powder by weight and heating it in a vacuum furnace at approximately 700°C. In the example electrode shown in Figure 2, both the tungsten carbide (WC) powder and the cobalt (Co) powder used had an average particle size of approximately 3 μm or less. When the particle size was varied to examine the electrode performance, it was found that when the average particle size was approximately 5 μm or less, the electrode material could be melted by discharge and adhered to the workpiece. However, when the particle size exceeded this, the electrode material adhered, but in a powdery state, and the adhesion was black and rough to the naked eye. The strength of the electrode increases from a heating temperature of about 600°C, and electrodes heated up to about 800°C are suitable for attaching material to workpieces using discharge coating. Below about 600°C, the electrode strength is barely strengthened and it is easily destroyed, making it difficult to use for discharge coating. Conversely, above about 1200°C, the strength becomes almost the same as that in a sintered state, making it difficult to transfer the electrode material to the workpiece. Therefore, the heating temperature of the electrodes is preferably about 600 to 800°C, and the temperature should be determined by considering how much strength the electrodes should have within that range for practical use. The above has been described for electrodes made of a mixed powder of tungsten carbide (WC) powder and cobalt (Co) powder, but the appropriate heating temperature range is roughly the same for electrodes made of a mixed powder of other hard materials, such as titanium carbide (TiC) and nickel (Ni).

[0020] On the other hand, it was found that the composition of the electrode also has a significant effect on whether or not the electrode material can be piled up thickly. In the case of an electrode made of tungsten carbide (WC) powder and cobalt (Co) powder, when the proportion of cobalt (Co) exceeded approximately 10% by weight, more preferably 13%, the electrode material melted and adhered firmly to the workpiece. When the melting point was 10% or less, the electrode material adhered to the workpiece, but the material was not melted sufficiently, and the adhesion was such that it appeared black and rough to the naked eye, and it peeled off in pieces when rubbed. As the proportion of cobalt (Co) increases, the deposited electrode material melts more easily and adheres more firmly, appearing glossy in appearance. In particular, when the proportion of cobalt (Co) exceeds approximately 30% by weight, it becomes easier to build up a thick layer of electrode material. Figure 3 shows an example of a discharge crater formed on the surface of a steel material using the electrode rod of the present invention under the same conditions as those shown in Figure 7, which has already been disclosed and explained as the prior art. This is an elemental mapping image of the same field of view as the electron microscope (SEM) photograph (top photograph) of material deposited by a single discharge. The elemental mapping image shows the results of mapping Fe, Co, and W. The processing conditions were the same as in Figure 7, with a current value of approximately 60 A and a pulse width of approximately 130 μs. However, the results differed from those of conventional technology, as it was found that the electrode components tungsten (tungsten (W) which is a constituent element of tungsten carbide) and cobalt (Co) were present in the discharge marks, indicating that the electrode material was successfully transferred to the workpiece.

[0021] The present inventors further conducted comparative studies on combinations of other hard metal carbide materials and metals, and obtained the following findings. That is, titanium carbide (TiC) powder and nickel (Ni) powder were mixed and similar discharge coating tests were performed. In the case of an electrode made of tungsten carbide (WC) powder and cobalt (Co) powder, the film formation was good when the cobalt (Co) ratio exceeded approximately 10% by weight, more preferably 13%, and when it exceeded approximately 30%, build-up became even easier. When the melting point was 10% or less, the electrode material adhered to the workpiece, but the material was not melted sufficiently, and the adhesion was such that it appeared black and rough to the naked eye, and it peeled off in pieces when rubbed. In the case of electrodes made of titanium carbide (TiC) powder and nickel (Ni) powder, film formation became good when the weight ratio of nickel (Ni) was around 25%, more preferably 30%, and build-up became easy when the weight ratio was around 55%. At first glance, it appears that the ratio of the metals cobalt (Co) and nickel (Ni) is different between an electrode made of tungsten carbide (WC) powder and cobalt (Co) powder and an electrode made of titanium carbide (TiC) powder and nickel (Ni) powder. However, when viewed in terms of volumetric proportion, the ratio of the metal components that result in good film formation is approximately 17%, more preferably approximately 20% or more, and the metal components that result in easy build-up are approximately 40% or more, which is almost the same, and it was found that the ratio of these metal components is important.

[0022] The above calculation is outlined below. As a specific example, first, a case where an electrode is made of tungsten carbide (WC) powder and cobalt (Co) powder, and the weight ratio of cobalt (Co) is 13%, will be described. The density of tungsten carbide (WC) is 15.6 and the density of cobalt (Co) is 8.9, so if the weight percentage of cobalt (Co) is 13%, the volume percentage of cobalt (Co) is as follows. (13 / 8.9) / {(13 / 8.9)+(100-13) / 15.6} ≒ 0.20 = 20%.

[0023] Next, the case of an electrode made of titanium carbide (TiC) powder and nickel (Ni) powder will be described. Since the density of titanium carbide (TiC) is 4.93 and the density of nickel (Ni) is 8.9, the volume fraction of nickel (Ni) when the weight fraction of nickel (Ni) is 30% is as follows. (30 / 8.9) / {(30 / 8.9)+(100-30) / 4.93} ≒ 0.19 = 19%, which is roughly 20%.

[0024] As mentioned above, cobalt (Co) and nickel (Ni) are given as typical examples of metal components used as electrode binders. This is because it is well known that cobalt (Co) and titanium carbide (TiC) have good compatibility as sintered material components. However, the present invention is not necessarily limited to this combination. For example, iron (Fe) is known to be a metal with properties very similar to those of cobalt (Co) and nickel (Ni). Iron (Fe), cobalt (Co), and nickel (Ni) have similar properties and are collectively referred to as iron-group elements, and are often used as binders for sintered materials. In this regard, it is true that these three elements are the most suitable binders in the present invention as well. However, according to the research results of the present inventors, it has been confirmed that in the present invention, the metal elements that are binders do not need to be limited to iron group elements. For example, titanium (Ti), an active element that easily forms carbides and oxides, can also be used as a binder. For example, using titanium (Ti) as a binder for titanium carbide (TiC) made it easy to create a good coating. However, because titanium (Ti) is a sticky metal, it is difficult to create a fine powder with a particle size of less than a few microns. Therefore, it was more effective to use titanium hydride (TiH2), which is brittle and easy to crush, and mix it with titanium carbide (TiC) powder. During the mixing process, this was crushed into fine particles, and the hydrogen was released during the electrode heating process to produce titanium (Ti) powder.

[0025] FIG. 4 shows an explanatory diagram of an improved embodiment of the present invention. In FIG. 4, 401 is an electrode, 402 is an electrode holder, 403 is an inert gas injection nozzle that injects and supplies inert gas to the discharge point at the tip of the electrode, 404 is the inert gas injected from the inert gas injection nozzle 403, 405 is a workpiece, 406 is a power supply device that applies a voltage between the electrode 401 and the workpiece 405 to generate a discharge, and 407 is the discharge generated between the electrode 401 and the workpiece 405. The electrode 401 is held by an electrode holder 402 and rotated by a rotating device (not shown). It may be connected to a vibrating device instead of the rotating device. The rotating device and vibrating device are insulated from the electrode 401 and electrode holder 402, and the electrode holder is powered by a power supply 406 via a power supply part such as a brush (not shown). The other pole of the power supply 406 is connected to the workpiece 405. The inert gas injection nozzle 403 is a nozzle that injects an inert gas such as Ar (argon) gas toward the point where discharge occurs when the tip of the electrode 401 is released from contact with the workpiece 405. In the drawing, it is installed to the side of the electrode, but it may of course be installed coaxially with the electrode.

[0026] 5 shows a detailed explanatory diagram of electrode 401. In the figure, 511 is the electrode material, which is made by compressing and molding a powder mixture of about 70% tungsten carbide (WC) powder and about 30% cobalt (Co) by weight, and heating it to about 700°C in a vacuum furnace. 512 is a coating agent that covers the surface of electrode 401. The manufacturing method, components, etc. of electrode 401 are the same as those described for electrode 101 (relevant paragraphs

[0018] to

[0024] ), except for the surface coating 512, and therefore will not be described here.

[0027] Electrode 101 has high performance as an electrode for discharge coating, but has the drawback of low strength. The difference in strength is obvious compared to a sintered electrode, and great care must be taken not to damage the electrode when performing discharge coating. Therefore, electrode 401 is an electrode with increased strength compared to the fragile electrode 101. That is, the electrode 401 is coated on the outside of the electrode rod to increase its strength. As the coating material, good results were obtained when a low-melting-point material such as zinc (Zn) or tin (Sn) was applied to the surface. An even easier method was to apply cyanoacrylate to the surface. Cyanoacrylate is a material used as an adhesive, and when applied to the electrode surface, it hardens, significantly increasing the electrode's strength. However, because cyanoacrylate is an insulator, it is necessary to remove the cyanoacrylate from the power supply part of the electrode as shown in Figure 5. As for the discharge part at the other end of the electrode, if the tip is not coated, a discharge can be generated, and the cyanoacrylate applied to the side will be removed by the heat of the discharge as the electrode wears away, so there is no particular problem if the cyanoacrylate is removed only from the tip beforehand. It goes without saying that the coating material is not limited to zinc (Zn), tin (Sn), or cyanoacrylate, and in relation to the object and desired effects of the present invention, various adhesives, such as starch-based adhesives, natural rubber-based adhesives, glue, acrylic resin-based adhesives, epoxy resin-based adhesives, vinyl chloride resin solvent-based adhesives, vinyl acetate resin emulsion adhesives, silicone-based adhesives, nitrocellulose adhesives, and phenolic resin-based adhesives, are also acceptable, although their performance may be somewhat inferior.

[0028] (Embodiment 2) FIG. 6 shows an explanatory diagram of the second embodiment of the present invention. 6, 601 is an electrode, 602 is an electrode holder, 603 is an inert gas injection nozzle that injects and supplies inert gas to the discharge point at the tip of the electrode, 604 is the inert gas injected from the inert gas injection nozzle 603, 605 is a workpiece, 606 is a power supply device that applies a voltage between the electrode 601 and the workpiece 605 to generate a discharge, 607 is a discharge generated between the electrode 601 and the workpiece 605, 608 is a laser light irradiation nozzle that is connected to a laser oscillator (not shown), and 609 is a laser light emitted from the laser light irradiation nozzle 608. The electrode 601 is held by an electrode holder 602 and rotated by a rotating device (not shown). It may be connected to a vibrating device instead of the rotating device. The rotating device and vibrating device are insulated from the electrode 601 and electrode holder 602, and the electrode holder is powered by a power supply 606 via a power supply part such as a brush (not shown). The other pole of the power supply 606 is connected to the workpiece 605. The inert gas injection nozzle 603 is a nozzle that injects an inert gas such as Ar (argon) gas toward the point where discharge occurs when the tip of the electrode 601 is released from contact with the workpiece 605. In the drawing, it is installed to the side of the electrode, but it may of course be installed coaxially with the electrode.

[0029] Next, the operation and function of the device in FIG. 6 will be described. The electrode 601 and electrode holder 602 are attached to a device body (not shown) and rotated by a rotating device attached to the device body. The device body is held by hand or by a mechanical device such as a robot. The tip of the electrode 601 is placed against the portion of the workpiece 605 to be coated with discharge coating. The electrode 601 is rotated while applying voltage from a power supply 606. The electrode 601 and the workpiece 605 rub against each other due to the relative speed, repeatedly shorting and opening the contact state, generating a discharge at the timing between these states. The power supply 606 may be a known power supply such as those described in the aforementioned patent documents, as long as it is equipped with a DC power supply and a switching element so that the discharge can be pulsed. Alternatively, a power supply with a current-limiting resistor and a switching element connected in series to the DC power supply is also acceptable. In any case, it is preferable that the discharge conditions, such as the current value and pulse width, can be adjusted by the power supply voltage, the capacitor for storing charge, and the control method of the switching element. When a discharge occurs, the heat melts the electrode at the discharge point, allowing it to adhere to the workpiece. In this example, a rotating device was used to drive the electrode 601 and electrode holder 602. However, any device capable of imparting relative motion to the electrode 601 and workpiece 605 may be used instead of a rotating device. Laser light 609 emitted from the laser light emission nozzle 608 is irradiated onto the electrode material adhered to the workpiece by the discharge, remelting the electrode material adhered to the workpiece and creating a smooth surface. The beam irradiated onto the electrode material adhered to the workpiece by the discharge can be a laser or an electron beam, but because an electron beam must be placed in a vacuum, laser light is superior in terms of ease of operation in production sites.

[0030] As explained in the first embodiment, according to the present invention, it is possible to deposit materials such as cemented carbide using only discharge coating without using an energy beam such as a laser beam, but it is also true that a certain level of skill is required to deposit a clean, uniform deposit. However, the use of an energy beam such as a laser beam has the advantage that even an unskilled worker can relatively easily create a flat deposit surface by first depositing the electrode material in a rough state and then irradiating it with an energy beam such as a laser beam. When an unskilled worker performs discharge coating using only discharge, depending on the conditions, the surface may become rough with a surface roughness exceeding 100 μmRz, but this problem can be solved by irradiating it with an energy beam such as laser light. For example, when metal molds need to be repaired on-site using discharge coating, there are cases where an experienced worker cannot perform the process. In such cases, if discharge coating using only discharge is used, once a rough surface with large irregularities is created, subsequent discharge coatings will prioritize the buildup on the convex parts, further exacerbating the surface irregularities. In such cases, it is possible to improve the buildup surface by irradiating it with laser light when the surface is not too uneven, and then add additional discharge coating buildup using discharge. By repeating the discharge and laser process, even an unskilled worker can create a smooth, uniform buildup layer.

[0031] In addition, in the second embodiment, the technical content of the build-up portion by discharge is the same as that shown in the explanation section of the first embodiment (relevant section: paragraphs

[0019] to

[0027] ). [Industrial Applicability]

[0032] The electrical discharge coating apparatus and electrical discharge coating method of the present invention solve the problem that, in the past, when attempting to coat a workpiece with a hard material such as cemented carbide or cermet by electrical discharge coating, the hard material only adhered in a patchy manner, and it was not possible to coat the workpiece surface neatly or to build up a thick layer, and it becomes possible to more densely and thickly adhere hard material to molds and machine parts. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a schematic diagram of an electric discharge coating apparatus according to an embodiment of the present invention. [Figure 2] 1 is an explanatory diagram of an electrode that is a part of an electric discharge coating apparatus according to an embodiment of the present invention. [Figure 3] 1 is an explanatory diagram of discharge marks formed on a workpiece by an electric discharge coating apparatus according to an embodiment of the present invention. FIG. [Figure 4] 1 is a schematic diagram of an improved version of an electric discharge coating apparatus according to an embodiment of the present invention. [Figure 5] 1 is an explanatory diagram of an electrode portion of an electric discharge coating apparatus according to an embodiment of the present invention; [Figure 6] 1 is an explanatory diagram of an electrode portion of an electric discharge coating apparatus according to an embodiment of the present invention; [Figure 7] FIG. 1 is an explanatory diagram of discharge craters formed by a conventional discharge coating device. [Figure 8] FIG. 1 is an explanatory diagram of discharge craters formed by a conventional discharge coating device. [Explanation of symbols]

[0034] 101 Electrode 102 Electrode holder 103 Inert gas injection nozzle 104 Inert Gas 105 Workpiece 106 Power supply 107 Discharge 401 Electrode 402 Electrode holder 403 Inert gas injection nozzle 404 Inert Gas 405 Workpiece 406 Power Supply 407 Discharge 511 Electrode materials 512 Coating 601 Electrode 602 Electrode holder 603 Inert gas injection nozzle 604 Inert gases 605 Workpiece 606 Power Supply 607 Discharge 608 Laser light emission nozzle 609 Laser Light

Claims

1. A semi-sintered electrode obtained by compressing and molding powder of a metal or conductive metal workpiece and then heating it at a temperature below the sintering temperature; a power supply device that applies a voltage between the electrode and the workpiece and generates a discharge during a transition period between contact and release between the electrode and the workpiece; an electrode driving device that manually or mechanically creates a relative movement between the electrode and the workpiece, repeatedly contacting and releasing the electrode; an inert gas supply device for supplying an inert gas for preventing oxidation between the electrodes; An electrical discharge coating device is used to deposit the electrode material melted by electrical discharge generated between the electrode and the workpiece onto the workpiece.

2. 2. The discharge coating apparatus according to claim 1, wherein the surface of the electrode is coated with a conductive material or an insulating material.

3. 3. The discharge coating apparatus according to claim 2, wherein the coating material is cyanoacrylate.

4. 2. The discharge coating apparatus according to claim 1, wherein the material of the electrode is mainly composed of a metal carbide and a metal binder.

5. 5. The discharge coating apparatus according to claim 4, wherein the volume ratio of the metal as a binder in the material of the electrode is 17% or more.

6. A semi-sintered electrode obtained by compressing and molding powder of a metal or conductive metal workpiece and then heating it at a temperature below the sintering temperature; a power supply device that applies a voltage between the electrode and the workpiece and generates a discharge during a transition period between contact and release between the electrode and the workpiece; an electrode driving device that manually or mechanically creates a relative movement between the electrode and the workpiece, repeatedly contacting and releasing the electrode; an inert gas supply device for supplying an inert gas for preventing oxidation between the electrodes; The electrode material is melted by an electric discharge generated between the electrode and the workpiece, and the melted electrode material is deposited on the workpiece. An electrical discharge coating apparatus having an energy beam irradiation device that melts the electrode material adhered to the workpiece.

7. 7. The discharge coating apparatus according to claim 6, wherein the surface of the electrode is coated with a conductive material or an insulating material.

8. 8. The discharge coating apparatus according to claim 7, wherein the coating material is cyanoacrylate.

9. 7. The discharge coating apparatus according to claim 6, wherein the material of the electrode is mainly composed of a metal carbide and a metal binder.

10. 10. The electrical discharge coating apparatus according to claim 9, wherein the volume ratio of the metal as a binder in the material of the electrode is 17% or more.

11. This is an electrical discharge coating method in which a semi-sintered electrode is formed by compressing powder of a metal or conductive metal workpiece and then heating it to a temperature below the sintering temperature, and an inert gas is supplied between the workpiece and the electrode to prevent oxidation. While a voltage is applied, a state of relative movement is created between the electrode and the workpiece manually or mechanically, and contact and release are repeated, generating an electrical discharge during the transition period between contact and release, and the electrode material melted by the generated electrical discharge is deposited on the surface of the workpiece.

12. 12. The electrical discharge coating method according to claim 11, wherein the surface of the electrode is coated with a conductive or insulating material.

13. 13. The electrical discharge coating method of claim 12, wherein the coating material is a cyanoacrylate.

14. 12. The electrical discharge coating method according to claim 11, wherein the material of the electrode is mainly composed of a metal carbide and a metal binder.

15. 15. The electrical discharge coating method according to claim 14, wherein the volume ratio of the metal as the binder in the material of the electrode is 17% or more.

16. A semi-sintered electrode is formed by compressing powder of a metal or conductive metal workpiece and then heating it to a temperature below the temperature at which sintering occurs, and an inert gas is supplied between the workpiece and the electrode to prevent oxidation. While a voltage is applied, a state of relative movement is created between the electrode and the workpiece manually or mechanically, and contact and release are repeated, generating an electric discharge during the transition period between contact and release, causing the electrode material to melt and adhere to the surface of the workpiece. The discharge coating method involves irradiating the workpiece with an energy beam that melts the electrode material adhered to the workpiece.

17. 17. The electrical discharge coating method according to claim 16, wherein the surface of the electrode is coated with a conductive material or an insulating material.

18. 18. The electrical discharge coating method of claim 17, wherein the coating material is a cyanoacrylate.

19. 17. The electrical discharge coating method according to claim 16, wherein the material of the electrode is mainly composed of a metal carbide and a metal binder.

20. 20. The electrical discharge coating method according to claim 19, wherein the volume ratio of the metal as the binder in the material of the electrode is 17% or more.

21. 21. The electrical discharge coating method according to claim 16, wherein the step of adhering the electrode material melted by electrical discharge to the surface of the workpiece and the step of irradiating the workpiece with an energy beam to melt the electrode material adhered to the workpiece are repeated.

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