JP2015067879A - Manufacturing method of electrode for discharge surface treatment, and discharge surface treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten time from manufacture of granulated powder 9 until sintering of a molding 39.SOLUTION: Cobalt alloy powder 5 containing scaly chromium which is pulverized by a jet mill is used as an electrode material, the cobalt alloy powder 5 containing scaly chromium is input into a cylindrical granulation container 7 whose axis 7s is inclined in a vertical direction VD, and the granulation container 7 is rotated about the axis 7s, by which dry granulation is performed to the cobalt alloy powder 5 containing scaly chromium to manufacture spherical granulated powder 9.

Description

  The present invention relates to a manufacturing method for manufacturing a discharge surface treatment electrode used when, for example, a wear-resistant film is formed on a portion to be processed of a metal workpiece using discharge energy.

  In recent years, various developments have been made on discharge surface treatment electrodes, and discharge surface treatment electrodes are usually produced by the following method (normal production method).

  Metal powder produced by atomization or ball mill or the like is used as an electrode material, and the metal powder is granulated. Specifically, a metal powder and a binder such as an acrylic polymer are put into a stirring vessel in which a solution such as isopropyl alcohol is stored, and the inside of the stirring vessel is stirred to mix the metal powder, the solution, the binder, and the like. A slurry is formed. Subsequently, by spraying the slurry into the drying container from the nozzle of the spray dryer while maintaining the inside of the drying container of the spray dryer in a high-temperature nitrogen gas atmosphere using a spray dryer, the solution in the slurry is dried. A spherical granulated powder made of an aggregate of metal powder containing a binder is manufactured.

  After the granulated powder is manufactured, the granulated powder is filled in the molding die, and the granulated powder in the molding die is compression-molded by using a cold press device, thereby forming the granulated powder. Make a body. Subsequently, the molded body is set in the heat treatment furnace, and the temperature of the molded body (in other words, the temperature in the heat treatment furnace) is set to the scattering temperature of the binder while the heat treatment furnace is maintained in a non-oxidizing atmosphere. The binder is degreased from the molded body by raising the temperature up to and holding for a certain period of time. Furthermore, in a state where the inside of the heat treatment furnace is maintained in a non-oxidizing atmosphere, the temperature of the molded body is raised to the sintering temperature of the metal powder and is maintained for a certain time, whereby the molded body is fired and sintered.

  As described above, an electrode for discharge surface treatment made of a sintered compact can be produced.

  In addition, there exists a thing shown to patent document 1 as a prior art relevant to this invention.

JP 2006-249462 A

  By the way, in the normal manufacturing method, since the binder is used when granulating the metal powder, the molded body is set in the heat treatment furnace before sintering the molded body as described above. In this state, it is necessary to raise the temperature of the molded body to the scattering temperature of the binder and hold it for a certain time to degrease the binder from the molded body. For this reason, there is a problem that it takes a long time from the production of the granulated powder to the sintering of the compact, and it is difficult to sufficiently increase the productivity (manufacturability) of the discharge surface treatment electrode.

  In addition, although the binder is degreased from the molded body, the binder residue tends to remain inside the discharge surface treatment electrode made of a sintered molded body, and if the binder residue remains, the density of the discharge surface treatment electrode However, it becomes non-uniform along the axial direction of the electrode for discharge surface treatment, and there is a problem that quality (uniformity) varies in the film formed on the treated portion of the metal workpiece using the discharge energy.

  Therefore, an object of the present invention is to provide a method for manufacturing a discharge surface treatment electrode having a novel configuration, which can solve the above-described problems.

  In order to solve the above-mentioned problems, the inventors of the present invention tried to granulate metal powder by various methods, and as a result, cobalt alloy powder containing flaky chromium pulverized by a jet mill as a granulation target was obtained. When used, a binder is used simply by putting cobalt alloy powder containing chromium into a cylindrical granulation vessel whose axis is inclined with respect to the vertical direction, and rotating the granulation vessel around its axis. Even if it is not, it is possible to produce a spherical granulated powder comprising an aggregate of cobalt alloy powders containing chromium as shown in FIGS. 7 (a) and 7 (b) by dry granulating cobalt alloy powder containing chromium. As a result, the present invention has been completed. This is considered to be because the property that the cobalt alloy powder containing scaly chromium is easily entangled in the granulation container is effectively and effectively exhibited. Although illustration is omitted, even when an amorphous metal powder produced by another mechanical pulverization method such as a cobalt alloy powder containing irregular chrome pulverized by a ball mill or bead mill is used as an electrode material, It has been found that spherical granulated powder can be produced.

  A first feature of the present invention is a manufacturing method for manufacturing an electrode for discharge surface treatment used when forming a coating film on a processing target portion of a metal workpiece using discharge energy, and a mechanical pulverization method Is used as an electrode material, the metal powder is put into a cylindrical granulation container whose axis is inclined with respect to the vertical direction, and the granulation container is placed around the axis. The metal powder is dry-granulated (dry granulation) by rotating or putting the metal powder in another granulation container and vibrating or rocking the other granulation container. A granulating step for producing a spherical granulated powder composed of an aggregate of the metal powder, and after completion of the granulating step, the granulated powder is filled in the molding die, Forming the granulated powder by compression molding the granulated powder A compression step of fabricating, after completion of the granulation step, and subject matter that anda firing step of sintering and firing the shaped body.

  Here, the “metal workpiece” means not only a metal workpiece as a metal material but also a metal component such as a gas turbine component. The “metal powder” is meant to include pure metal powder such as nickel powder and cobalt powder, alloy powder such as cobalt alloy powder containing chromium, and mixed powder thereof.

  According to the first feature, the metal powder having an indefinite shape generated by a mechanical pulverization method is used as an electrode material, and the metal powder is put into the granulation container whose axis is inclined with respect to the vertical direction. Since the granulation container is rotated around its axis, the metal powder can be dry granulated (dry granulation) without using a binder to produce the spherical granulated powder. it can. Further, the metal powder is put into the granulation container, and instead of rotating the granulation container around its axis, the metal powder is put into the another granulation container, and the another granulation is performed. Similarly, when the container is vibrated or swung, it is presumed that the spherical granulated powder can be produced without using a binder. This eliminates the step of degreasing the binder from the molded body after producing the granulated powder, and the density of the discharge surface treatment electrode is substantially uniform along the axial direction of the discharge surface treatment electrode. Can be.

  A second feature of the present invention is a discharge surface treatment method for forming a film on a portion to be treated of a metal workpiece using discharge energy, and a method for manufacturing a discharge surface treatment electrode according to the first feature. The discharge surface treatment electrode manufactured by the method is used, and a pulsed discharge is generated between the discharge surface treatment electrode and the metal workpiece to be treated, and the metal workpiece is treated by the discharge energy. The gist is that the electrode material of the electrode for discharge surface treatment or a reaction material of the electrode material is welded to the portion to be treated of the metal workpiece to form the coating film while locally melting.

  According to the present invention, since the step of degreasing the binder from the molded body after the granulated powder is manufactured can be omitted, the time until the molded body is sintered after the granulated powder is manufactured is reduced. It is possible to significantly shorten the productivity (manufacturability) of the discharge surface treatment electrode.

  In addition, since the density of the discharge surface treatment electrode can be made substantially uniform along the axial direction of the discharge surface treatment electrode, the coating formed on the portion to be treated of the metal workpiece using discharge energy. Variations in quality (uniformity) can be eliminated and the quality of the coating film can be stabilized.

Drawing 1 is a mimetic diagram explaining the granulation process in the manufacturing method of the electrode for discharge surface treatment concerning a 1st embodiment. FIG. 2 is a schematic diagram for explaining a classification step in the method for manufacturing the electrode for discharge surface treatment according to the first embodiment. FIG. 3A is a diagram showing a state in which the granulated powder is filled in the molding die, and FIG. 3B is a diagram showing a compression firing step and a first step in the method for manufacturing an electrode for discharge surface treatment according to the first embodiment. It is a schematic diagram explaining the compression process in the manufacturing method of the electrode for discharge surface treatment which concerns on 4th Embodiment. FIG. 4A is a schematic diagram for explaining a compression step in the method for manufacturing a discharge surface treatment electrode according to the second embodiment, and FIG. 4B is a process for manufacturing the discharge surface treatment electrode according to the second embodiment. It is a schematic diagram explaining the baking process in a method. FIG. 5 is a schematic diagram for explaining a CIP process in the method for manufacturing an electrode for discharge surface treatment according to the third embodiment and the fourth embodiment. FIG. 6 is a schematic diagram for explaining a discharge surface treatment method according to the fifth embodiment. FIG. 7A is a photograph showing the granulated powder in the granulation container, and FIG. 7B is a partially enlarged photograph of FIG. 7A.

(First embodiment)
A method for manufacturing the electrode for discharge surface treatment according to the first embodiment will be described with reference to FIGS. 1 to 3A, 3B, and 6. FIG.

  The method for manufacturing a discharge surface treatment electrode according to the first embodiment of the present invention is a method for manufacturing the discharge surface treatment electrode 1 as shown in FIG. 6, and includes a granulation step, a classification step, A compression firing process (a process combining the compression process and the firing process). And the specific content of each process in the manufacturing method of the electrode for discharge surface treatment which concerns on 1st Embodiment of this invention is as follows. The discharge surface treatment electrode 1 is used when, for example, the coating 3 having wear resistance is formed on the treated portion Wa of the metal workpiece W by using discharge energy.

Granulation step As shown in FIG. 1, cobalt alloy powder 5 containing flaky chromium pulverized by a jet mill and having an average particle size of 5 μm or less is used as an electrode material. Then, the cobalt alloy powder 5 containing scaly (an example of indefinite shape) chromium is put into a cylindrical granulation vessel 7 whose axis 7s is inclined with respect to the vertical direction VD, and the granulation vessel 7 is placed on its axis. Rotate around the heart 7s. Thereby, the cobalt alloy powder 5 containing chromium is granulated dry (dry granulation), and the spherical granulated powder 9 which consists of the aggregate | assembly of the cobalt alloy powder 5 containing chromium can be manufactured. Instead of putting the cobalt alloy powder 5 containing scaly chrome into the granulation vessel 7 and rotating the granulation vessel 7 about its axis 7s, another cylindrical granulation vessel (not shown) The cobalt alloy powder 5 containing scale-like chromium may be put in and another granulation container may be vibrated or swung.

  Here, in the cobalt alloy powder 5 containing scaly chromium, cobalt alloy powder 11 containing spherical chromium produced by an atomizing method, a reduction method, or a carbonyl method and having an average particle diameter of 5 μm or less is mixed. In this case, the ratio of the cobalt alloy powder 11 containing spherical chromium to the entire cobalt alloy powders 5 and 11 containing chromium (the whole electrode material) needs to be set to 10% by weight or less. When the ratio of the cobalt alloy powder 11 containing spherical chromium to the whole electrode material exceeds 10% by weight, the property that the cobalt alloy powder 5 containing scaly chromium is easily entangled in the granulation vessel 7 effectively and effectively. It is because it becomes difficult to make it show. Further, in place of the cobalt alloy powder 5 containing scaly chromium, cobalt alloy powder (not shown) containing irregular-shaped chromium pulverized by a ball mill or bead mill may be used as an electrode material.

Classification Step After completion of the granulation step, as shown in FIG. 2, the granulated powder 9 is put into the sieve container 15 of the vibrating sieve device 13 to vibrate the sieve container 15. Thereby, the granulated powder 9 is classified by a pair of sieve nets 17 and 19 disposed in the sieve container 15, and within a target particle size range (in the embodiment of the present invention, an average particle size of 100 to 200 μm) of granulated powder 9 can be recovered.

Compression and firing step After the classification step, as shown in FIG. 3A, a granulated powder 9 is filled into the molding die 21 using a molding die 21 made of graphite. Here, the molding die 21 includes a die 23 having a die hole 23h, an upper punch 25 provided in an upper portion of the die hole 23h of the die 23 so as to be movable in the vertical direction, and a die hole 23h of the die 23. The lower punch 27 is provided at the lower part of the lower punch 27 so as to be movable in the vertical direction.

  Next, as shown in FIG. 3B, the molding die 21 is set between the upper ram 33 and the lower ram 35 in the heat treatment furnace 31 of the hot press device (hot press device) 29. Then, in a state where the inside of the heat treatment furnace 31 is maintained in a non-oxidizing atmosphere, the upper ram 33 is moved downward relative to the lower ram 35, and the molding metal is heated by the electric heating method using the power source 37. The temperature in the mold 21 is raised to the sintering temperature (firing temperature) of the electrode material and held for a certain time. As a result, the compact 39 can be fired and sintered while the granulated powder 9 in the molding die 21 is compression-molded to produce the compact 39 made of the granulated powder 9.

  Here, instead of heating by the energization heating method using the power source 37, the molding die is heated by the resistance heating method using a resistor (not shown) or the heating by the dielectric heating method using a coil (not shown). The temperature in 21 may be raised to the sintering temperature of the electrode material and held for a certain period of time. Note that the non-oxidizing atmosphere includes a vacuum atmosphere, an inert gas atmosphere such as nitrogen gas, a hydrogen gas atmosphere, a CO gas atmosphere, and the like, and the sintering temperature of the electrode material is, for example, 0.5 to 0.8 Tm ° C. (Tm: melting point of electrode material).

  As described above, the discharge surface treatment electrode 1 made of the sintered compact 39 can be manufactured.

  Then, the effect | action and effect of 1st Embodiment are demonstrated.

  Cobalt alloy powder 5 containing flaky chromium pulverized by a jet mill is used as an electrode material, and cobalt alloy powder 5 containing flaky chromium in granulation container 7 whose axis 7s is inclined with respect to vertical direction VD. (Including the cobalt alloy powder 5 containing scaly chrome mixed with the cobalt alloy powder 11 containing spherical chromium) and the granulation container 7 is rotated around its axis 7 s. Even if it does not use, the cobalt alloy powder 5 containing chromium can be granulated dry (dry granulation), and the granulated powder 9 of the cobalt alloy powder 5 containing spherical chromium can be manufactured. Also, instead of putting the cobalt alloy powder 5 containing scaly chrome into the granulation vessel 7 and rotating the granulation vessel 7 around its axis 7s, the scaly chrome is put into another granulation vessel. In the case where the cobalt alloy powder 5 is added and another granulation vessel is vibrated or swung, the granulated powder 9 of the cobalt alloy powder 5 containing spherical chromium is similarly manufactured without using a binder. Presumed to be possible. This eliminates the step of degreasing the binder from the compact 39 after the granulated powder 9 is manufactured, and the density of the discharge surface treatment electrode 1 is substantially uniform along the axial direction of the discharge surface treatment electrode 1. Can be.

  Therefore, according to the first embodiment, since the step of degreasing the binder from the molded body 39 after the granulated powder 9 is manufactured can be omitted, the molded body 39 is sintered after the granulated powder 9 is manufactured. Can be significantly shortened, and the productivity (manufacturability) of the discharge surface treatment electrode 1 can be sufficiently increased.

  Further, since the density of the discharge surface treatment electrode 1 can be made substantially uniform along the axial direction of the discharge surface treatment electrode 1, the coating film formed on the portion Wa to be processed of the metal workpiece W using the discharge energy The quality (uniformity) of 3 can be eliminated, and the quality of the coating 3 can be stabilized.

(Second Embodiment)
In the configuration of the method for manufacturing the electrode for discharge surface treatment according to the second embodiment, only the points different from the method for manufacturing the electrode for discharge surface treatment according to the first embodiment will be described with reference to FIGS. I will explain.

  The method for manufacturing an electrode for discharge surface treatment according to the second embodiment includes a compression step and a baking step instead of the compression baking step in the method for manufacturing the electrode for discharge surface treatment according to the first embodiment. And the concrete content of the compression process and baking process in the manufacturing method of the electrode for electrical discharge surface treatment which concerns on 2nd Embodiment is as follows.

Compression Process As shown in FIG. 4A, the molding die 21 is placed between the upper ram 43 and the lower ram 45 in the cold press device 41 in a state where the granulated powder 9 is filled in the molding die 21. set. Then, the upper ram 43 is moved downward relative to the lower ram 45, and the granulated powder 9 in the molding die 21 is compression-molded. Thereby, the molded object 39 which consists of the granulated powder 9 is producible.

  In the second embodiment, the molding die 21 need not be made of graphite.

Firing Step After the compression step is finished, as shown in FIG. 4 (b), the molded body 39 taken out from the molding die 21 (see FIG. 4 (a)) is set at a predetermined position in the heat treatment furnace 47. Then, with the inside of the heat treatment furnace 47 maintained in a non-oxidizing atmosphere, the temperature of the non-oxidizing atmosphere (temperature in the heat treatment furnace 47) is raised to the sintering temperature of the electrode material by the heater 49 of the heat treatment furnace 47. Allow to warm and hold for a period of time. Thereby, the molded object 39 can be baked and sintered.

  And also in 2nd Embodiment, there exists an effect | action and effect similar to the above-mentioned 1st Embodiment.

(Third embodiment)
In the configuration of the method for manufacturing the discharge surface treatment electrode according to the third embodiment, only differences from the method for manufacturing the discharge surface treatment electrode according to the second embodiment will be described with reference to FIG.

  The method for manufacturing the electrode for discharge surface treatment according to the third embodiment is in addition to each step (granulation step, classification step, compression step, firing step) in the method for manufacturing the electrode for discharge surface treatment according to the second embodiment. , CIP process. And the specific content of the CIP process in the manufacturing method of the electrode for electrical discharge surface treatment which concerns on 3rd Embodiment is as follows.

CIP Process After the compression process is completed and before the firing process is started, as shown in FIG. 5, the molded body 39 taken out from the molding die 21 (see FIG. 4A) is sealed in the rubber mold 51. To do. Then, the rubber mold 51 is immersed in the hydraulic fluid (pressurized fluid) S in the pressure vessel 53, and the compact 39 is uniformly applied by the action of the hydrostatic pressure (isotropic pressure) of the hydraulic fluid S in the pressure vessel 53. By pressing, the molded body 39 can be subjected to CIP processing.

  And according to 3rd Embodiment, since there exists an effect | action and effect similar to 1st Embodiment, since the CIP process was performed to the molded object 39 before the said baking process, the electrode 1 for discharge surface treatments The density of (see FIG. 6) can be made substantially more uniform along the axial direction of the discharge surface treatment electrode 1, and the discharge energy is used to form the processed portion Wa (see FIG. 6) of the metal workpiece W. The quality of the coated film 3 (see FIG. 6) can be further stabilized.

(Fourth embodiment)
In the configuration of the method for manufacturing the discharge surface treatment electrode according to the fourth embodiment, only differences from the method for manufacturing the discharge surface treatment electrode according to the third embodiment will be described with reference to FIG. .

  As shown in FIG. 3B, the compression step in the method for manufacturing the discharge surface treatment electrode according to the fourth embodiment uses a hot press device 29 as shown in FIG. 3B instead of the cold press device (see FIG. 4A). Used, the molding die 21 made of graphite is set between the upper ram 33 and the lower ram 35 in the heat treatment furnace 31 of the hot press apparatus 29. Then, in a state where the inside of the heat treatment furnace 31 is maintained in a non-oxidizing atmosphere, the upper ram 33 is moved downward relative to the lower ram 35, and the molding metal is heated by the electric heating method using the power source 37. The temperature in the mold 21 is raised to the temporary firing temperature (preliminary sintering temperature) of the electrode material and held for a certain time. Thereby, the compact 39 can be temporarily fired while the granulated powder 9 in the molding die 21 is compression-molded to produce the compact 39.

  Here, instead of heating by the energization heating method using the power source 37, the molding die is heated by the resistance heating method using a resistor (not shown) or the heating by the dielectric heating method using a coil (not shown). The temperature in 21 may be raised to the temporary firing temperature of the electrode material. In addition, the temporary firing temperature of the electrode material is, for example, 0.3 to 0.45 Tm ° C. (Tm: melting point of the electrode material).

  And also in 4th Embodiment, there exists an effect | action and effect similar to the above-mentioned 3rd Embodiment.

(Fifth embodiment)
A discharge surface treatment method according to the fifth embodiment will be described with reference to FIG.

  As shown in FIG. 6, the discharge surface treatment method according to the fifth embodiment is a method for forming a wear-resistant film 3 on the portion Wa of the metal workpiece W using discharge energy. The specific contents of the discharge surface treatment method according to the fifth embodiment are as follows.

  Using the discharge surface treatment electrode 1 according to any one of the first to fourth embodiments, the discharge surface treatment electrode 1 and the metal workpiece in the processing oil L stored in the machining tank 55. A pulse-like discharge is generated between the portion W to be processed Wa. Thereby, while locally melting the portion Wa to be processed of the metal workpiece W by the discharge energy, the electrode material of the discharge surface treatment electrode 1 or its reactant is welded to the portion to be processed Wa of the metal workpiece W, A wear-resistant coating 3 can be formed.

  According to the discharge surface treatment method according to the fifth embodiment, since the discharge surface treatment electrode 1 according to any one of the first to fourth embodiments is used, the discharge energy is reduced. It is possible to stabilize the quality of the coating 3 by eliminating variations in the quality (uniformity) of the coating 3 formed on the treated portion Wa of the metal workpiece W.

  In addition, this invention is not restricted to description of the above-mentioned embodiment, It can implement in a various aspect by making an appropriate change. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

  L: Processing oil, S: Hydraulic fluid, W: Metal workpiece, Wa: Processed part, 1: Electrode for discharge surface treatment, 3: Coating, 5: Cobalt alloy powder containing scaly chromium, 7: Granulation container 7s: Axis of granulation container, 9: Granulated powder, 11: Cobalt alloy powder containing spherical chromium, 13: Vibrating sieve device, 15: Sieve container, 17: Sieve net, 19: Sieve net, 21: Mold: 23: Die, 23h: Die hole, 25: Upper punch, 27: Lower punch, 29: Hot press apparatus, 31: Heat treatment furnace, 33: Upper ram, 35: Lower ram, 37: Power supply, 39 : Molded body, 41: Cold press device, 43: Upper ram, 45: Lower ram, 47: Heat treatment furnace, 49: Heater, 51: Rubber mold, 53: Pressure vessel, 55: Processing tank

Claims (6)

It is a manufacturing method for manufacturing an electrode for discharge surface treatment used when forming a film on a processed part of a metal workpiece using discharge energy,
Using an irregularly shaped metal powder produced by a mechanical pulverization method as an electrode material, the metal powder is put into a cylindrical granulation container whose axis is inclined with respect to the vertical direction. Rotating around the axis, or putting the metal powder in another granulation container, vibrating or rocking the other granulation container, granulate the metal powder dry, A granulating step for producing a spherical granulated powder comprising an aggregate of the metal powders;
After completion of the granulation step, the granulated powder is filled in the molding die, and the granulated powder in the molding die is compression-molded to produce a molded body made of the granulated powder. A compression process;
A method for producing an electrode for discharge surface treatment, comprising: a firing step of firing and sintering the compact after the granulation step.   The compression step and the firing step are performed in one step by firing and sintering the molded body while producing the molded body by compression molding the granulated powder in the molding die. The manufacturing method of the electrode for discharge surface treatment of Claim 1 characterized by the above-mentioned.   After the compression process is completed and before the firing process is started, the molded body is sealed in a rubber mold, and the molded body is uniformly pressurized by the action of the hydrostatic pressure of the hydraulic fluid in the pressure vessel. The method for producing an electrode for discharge surface treatment according to claim 1, further comprising: a CIP step of performing a CIP treatment on the molded body. In the compression step, the granulated powder is filled in the molding die, the granulated powder in the molding die is compression-molded to produce the molded body, and the molded body is temporarily fired. And
After the compression process is completed and before the firing process is started, the molded body is sealed in a rubber mold, and the molded body is uniformly pressurized by the action of the hydrostatic pressure of the hydraulic fluid in the pressure vessel. The method for producing an electrode for discharge surface treatment according to claim 1, further comprising: a CIP step of performing a CIP treatment on the molded body.   A classification step of classifying the granulated powder after the completion of the granulation step and before the compression step, and collecting the granulated powder within a target particle size range. The method for producing an electrode for discharge surface treatment according to any one of claims 1 to 4. A discharge surface treatment method for forming a film on a treated part of a metal workpiece using discharge energy,
A discharge surface treatment electrode manufactured by the method for manufacturing a discharge surface treatment electrode according to any one of claims 1 to 4, wherein the discharge surface treatment electrode and the metal workpiece are treated. A pulsed discharge is generated between the electrode material and the portion to be processed of the metal workpiece is locally melted by the discharge energy, while the electrode material of the electrode for discharge surface treatment or the reactant of the electrode material is A discharge surface treatment method, wherein the coating is formed by welding to a portion to be treated of the metal workpiece.