JP2016075327A - Manufacturing method of valve device, and valve device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To finish a padding part in a short time, to improve production efficiency.SOLUTION: In a valve device including a movable member operating with valve opening/closing and a stationary member sliding with the movable member, the surface of at least one of the movable member and stationary member is machined into an uneven shape as a processed part 100, and a padding part 102 is formed on the uneven surface of the processed part 100 after machining. The padding part 102 is formed by generating pulse-like discharge between an electrode constituted with a compact mainly comprising metal and the uneven surface of the processed part 100, and depositing the material of the electrode on the uneven surface of the processed part 100 and accumulating it thereon.SELECTED DRAWING: Figure 2

Description

  Embodiments described herein relate generally to a method for manufacturing a valve device and a valve device manufactured by the method.

  Steam turbines such as thermal power plants are equipped with various valve devices such as a main steam stop valve, a steam control valve, a reheat steam stop valve, an intermediate stop valve, and a turbine bypass valve in order to control the inflow of steam. ing.

  In the valve device described above, it is known that a movable member and a stationary member that is in sliding contact with the movable member, for example, a cobalt-based hard alloy having oxidation resistance on the sliding contact surface of a valve rod or a bush, is built up by electric discharge.

  FIG. 7 shows an example of a conventional electric discharge machining method in which a portion having a uniform thickness is applied to the portion to be processed by electric discharge.

  As shown in FIG. 7, a part to be processed 100 and a part of the electrode 101 are arranged in an electrically insulating liquid L (or in the air), the electrode 101 is connected to the cathode of the DC power source 103, and The processing unit 100 is connected to the anode of the DC power source 103. Then, in a state where a minute gap is maintained between the electrode 101 and the processing target 100, the voltage of the DC power source 103 is applied between the electrode 101 and the processing target 100 or is stopped by applying a pulse. The material of the electrode 101 is welded and deposited on the surface of the processing target portion 100 by the discharge energy.

  In this electrical discharge machining method, the base material is melted in units of electrode particles to form a built-up portion. Therefore, since the heat input to the base material of the processed portion is small, the build-up is performed without deforming the processed portion. It can be performed. Furthermore, since the electrode component is melted and bonded to the portion to be processed, the adhesion between the build-up portion and the base material of the portion to be processed is high, and the build-up portion does not peel off. In addition, this electric discharge machining method has a feature that a heat affected zone (HAZ: Heat-Affected Zone) is not formed on the surface layer of the base material of the portion to be processed because there is little heat input.

JP 2013-119921 A

  However, in a general electric discharge machining method, the electrode 101 is horizontally moved at a constant limited speed so that a built-up portion having a uniform thickness is formed over the entire portion to be processed. Since the whole is scanned, it takes a considerable time to complete the overlay.

  Problem to be solved by the invention is providing the valve apparatus manufactured by the manufacturing method of the valve apparatus which can complete a build-up part in a short time, and can improve production efficiency, and its manufacturing method.

  The valve device according to the embodiment is a valve device including a movable member that operates in accordance with opening and closing of the valve and a stationary member that is in sliding contact with the movable member, and at least one surface of the movable member and the stationary member is subjected to a processing target. Processed into a concavo-convex shape, and formed a build-up portion on the concavo-convex surface of the processed portion after processing, and the build-up portion is composed of an electrode composed of a molded body containing metal as a main component and the treatment target The electrode material is formed by welding and depositing the electrode material on the uneven surface of the portion to be processed by generating a pulsed discharge between the uneven surface of the portion.

  According to the present invention, the built-up portion can be completed in a short time, and the production efficiency can be improved.

Sectional drawing which shows the structural example of the valve apparatus using the member manufactured by the manufacturing method of 1st Embodiment. Sectional drawing which shows the cross-sectional shape of the to-be-processed part in each process (1st example). The conceptual diagram which shows an example of the drive mechanism used for a build-up process. Sectional drawing which shows the cross-sectional shape of the to-be-processed part in each process (2nd example). Sectional drawing which shows the cross-sectional shape of the to-be-processed part in each process (3rd example). Sectional drawing which shows the structural example of the valve apparatus using the member manufactured by the manufacturing method of 2nd Embodiment. The conceptual diagram which shows the principle which forms the build-up part in a to-be-processed part by an electrical discharge machining method.

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

[First Embodiment]
FIG. 1 is a steam control valve that is installed in a preceding stage of a valve device according to a first embodiment, not shown here, and used to control the rotational speed of a high-pressure turbine by controlling the amount of steam that flows in. It is sectional drawing which showed as an example. In the following description, reference is also made to FIG. 7 as necessary.

  The steam control valve includes a steam valve body 200, a bush 201, an upper lid 202, a valve seat 203 as a steam outlet, a valve body 204, a valve rod 205, an opening 207 as a steam inlet, an opening 208 as a steam outlet, a valve An opening 209 which is an insertion port for the rod 205 and the valve body 204 is provided. In the steam valve main body 200, the valve body 204 opens and closes the opening 208 of the valve seat 203 by the axial movement of the valve rod 205 inserted into the steam chamber 210 through the opening 209. The upper lid 202 is fixed to the upper part of the opening 209 of the steam valve main body 200 and closes the upper surface of the steam valve main body 200. A hydraulic drive mechanism 206 is installed above the upper lid 202, and a valve rod 205 is connected to the hydraulic drive mechanism 206 downward (vertical direction). The valve rod 205 is reciprocated up and down by a hydraulic drive mechanism 206. In the steam control valve, the through hole of the upper lid 202 becomes a sliding surface with the valve rod 205, and thus a cylindrical bush 201 made of a metal resistant to friction is inserted into this portion, and the axial direction is The moving valve rod 205 is guided by the bush 201 so that it does not shake sideways. The valve body 204 is provided so as to contact the valve seat 203 and open and close the opening of the valve seat 203. The valve body 204 is provided at the tip of the valve rod 205.

  Here, of the sliding parts in the steam control valve, the sliding contact surface between the valve rod 205 as the movable member and the bush 201 as the stationary member, specifically, the outer peripheral surface of the valve rod 205 and the inner periphery of the bush 201 At least one of the surfaces is a processing target.

  In this embodiment, after processing the surface of a to-be-processed part first as an uneven | corrugated shape as pre-processing, the build-up part is formed in the uneven | corrugated surface of the to-be-processed part after a process. When forming the build-up portion, the principle described with reference to FIG. 7 is used. That is, a pulsed discharge is generated between the electrode 101 formed of a molded body containing metal as a main component and the uneven surface formed on the processing target 100, and the material of the electrode 101 is changed to the processing target 100. The build-up part is formed by welding and depositing on the uneven surface of the film. Hereinafter, a specific example will be described in detail.

(Processing procedure)
FIG. 2 is a partially enlarged view showing an example of a processing method including steps (a) pre-processing, (b) build-up processing, and (c) finishing processing for the processing target 100.

(A) Pretreatment FIG. 2A shows a state in which pretreatment is performed before overlaying.

  In the pretreatment, the surface of the portion to be processed 100 is roughened by performing a process for mechanically processing the surface of the portion to be processed 100 (at least the region where the portion is to be built), for example, a satin finish, before performing the overlaying. Finish the shape.

  The satin treatment is a treatment method that mechanically roughens the surface of the treated portion 100 to literally make the surface of the treated portion 100 like pear skin, and the surface of the treated portion 100 is finished to a semi-glossy uneven surface called “pear texture”. . The height difference (depth) between the concave and convex is preferably 10 μm to 50 μm in order to obtain a build-up thickness by good discharge on the surface of the concave and convex surface.

  Although the surface after the matte treatment exhibits irregular irregularities on a macro scale, the microscopically, the concave portion (curved dent) 11 is uniform with respect to the outer surface before the matte finish as shown in FIG. On the other hand, a part of the outer surface before the satin treatment remains as a convex portion (protruding surface) 12. The surface (protruding surface) of the convex portion 12 serves as a reference surface for the overlaying process.

  In addition, the satin treatment for obtaining uneven textured skin may be performed on the entire surface of the processing target 100. You may make it apply only to the site | part. In addition, for example, in a long round bar such as a valve rod, it may be applied spirally with a predetermined interval in the axial direction, or it may be applied to a plurality of annular things arranged in the axial direction, It may be applied to a plurality of linear objects arranged in parallel in the axial direction. By doing so, it is possible to reduce the processing time and cost.

  As a mechanical means for obtaining uneven texture, for example, there is sand blasting. In this method, compressed air produced by a compressor is used, and a fine abrasive material is sprayed from the air nozzle onto the surface of the processing object 100 to make it uneven. The particle shape of the abrasive is preferably spherical, and the particle size is preferably larger than the particle size of the electrode material, for example, 10 microns or more. In addition, in the case of a stainless steel material such as SUS304, the material of the abrasive has the advantage that it does not wear the treated part 100 because it deforms itself even if it collides with the treated part 100 because of the ductile material. However, the present invention is not limited to this, and other steel types, silica sand, alumina and other ceramic-based abrasives may be used. In addition, as another method for obtaining uneven texture, shot blasting using steel-type shot balls may be employed.

  Further, in order to obtain uneven textured skin, instead of performing the above-described blasting by sand blasting or shot blasting, peening processing by shot peening or WPC (Wide Peening and Cleaning) may be performed.

  Shot peening is originally intended to suppress the tensile stress by creating a molecular compressive stress on the surface by striking a shot material on the welded portion, but when used in this embodiment, it is directed toward the surface of the processing target 100. Then, a process of roughening the surface of the portion to be processed 100 is performed by spraying a powdered shot material. Shot peening has a stronger working force than the aforementioned sandblasting.

  WPC is a surface modification technique in which fine particles are mixed with a compressible gas and collided at high speed. When WPC is used in the present embodiment, as in shot peening, the surface of the processing target 100 is sprayed with powder particles to roughen the surface, but the working force is stronger than shot peening, and Since high temperature heat is applied to the molecules on the metal surface of the portion to be processed 100 for a short time and the bonds between the crystal molecules of the surface molecules are strengthened, surface modification that improves the fatigue strength of the metal is possible.

  In order to effectively obtain the effect of this surface modification, the particles to be ejected are made of, for example, chromium (Cr) or chromium (Cr) compound particles, and peened. Thereby, the surface layer part of the to-be-processed part 100 can be alloyed by a normal temperature diffusion phenomenon, and the compound of chromium (Cr) and chromium (Cr) can be made to exist abundantly. In particular, the abundance of chromium (Cr) and chromium (Cr) compounds exist in the concave portion 11 and the bottom of the valley where the powder formed into particles by the peening treatment collides and penetrates.

The portion of the concave portion 11 rich in chromium (Cr) or chromium (Cr) compound is heated to the chromium (Cr) or chromium (Cr) compound because a pulsed discharge is generated in the build-up process described later. Since the oxidation treatment is performed, an oxide film containing chromium carbide (CrC) or chromium oxide (Cr ₂ O ₃ ) having superior oxidation resistance and protection can be formed.

(B) Build-up process The state where the build-up process was performed is shown in FIG.

  In the build-up process, a pulsed discharge is generated between the electrode 101 and the target portion 100 in a state where a certain minute gap is maintained between the above-described electrode 101 and the target portion 100 (the aforementioned reference surface). The electrode 101 is consumed and the material of the electrode 101 is deposited and deposited on the surface of the processing target 100, while the electrode 101 or the member to be processed is kept in a constant state while maintaining a certain minute gap. By moving at a speed, the entire surface of the processing target portion 100 is scanned to form the build-up portion 102. The details of the built-up portion 102 to be formed will be described later.

  An example of the drive mechanism used for the overlaying process is shown in FIG. Here, it is assumed that the portion to be processed 100 is on the surface of the valve stem 205 and the pretreatment has already been performed.

  A drive mechanism 300 shown in FIG. 3 includes an electric motor 301 that rotates the valve rod 205, a feed mechanism 302 that supports the electrode 101 and moves the electrode 101 along the axial direction of the valve rod 205, and the feed mechanism 302. And an electric motor 303 to be driven.

  The feed mechanism 302 includes a rotary shaft 304 provided with a feed screw, a block 305 provided with a feed screw in the same direction so as to mesh with the feed screw of the rotary shaft 304, and an electrode holding member attached to the block 305. Part 306.

  The electrode 101 is a molded electrode formed of a molded body formed by compressing or heat-treating a powder containing metal as a main component with a press. However, the electrode 101 is not limited thereto, and may be molded by other known methods. There is no problem.

  In such a configuration, the rotating shaft 304 of the feed mechanism 302 is rotated at a constant speed by the electric motor 303 while the valve rod 205 is rotated at a constant speed by the electric motor 301. Since the rotation shaft 304 and the block 305 are each provided with a feed screw, when the rotation shaft 304 rotates, the block 305 moves at a constant speed along the axial direction of the rotation shaft 304. Thereby, the electrode 101 held by the electrode holding part 306 moves at a constant speed along the axial direction of the valve stem 205.

  When the drive mechanism 300 is operated in this manner, the spiral built-up portion 102 is formed on the surface of the valve rod 205.

  Note that the drive mechanism 300 shown in FIG. 3 is an example, and the present invention is not limited to this. For example, instead of moving the electrode 101 in the axial direction of the valve stem 205, the electrode 101 may be moved in the circumferential direction of the valve stem 205. Further, instead of moving the electrode 101, the valve rod 205 may be moved in its axial direction or circumferential direction.

  By the way, as described in FIG. 2A, the surface of the processing target 100 before the build-up process has the arc-shaped concave portion 11, and on the other hand, a part of the outer surface before the satin processing is formed. The protrusion 12 remains. The surface area of the apex (surface) of the convex portion 12 is relatively small with respect to the surface area of the concave portion 11. Further, the convex portion 12 is closer to the convex portion 12 than the concave portion 11 is closer to the electrode 101 scanned along the surface of the processing target portion 100. Therefore, the discharge energy from the electrode 101 (the number of occurrences of pulsed discharge) acts more strongly on the convex portion 12 than on the concave portion 11. Here, if the feed rate is the same as the conventional one, the thickness of the build-up becomes thinner in the concave portion 11, whereas the convex portion 12 becomes thicker than necessary.

  Therefore, in the present embodiment, by moving the electrode 101 along the reference surface of the processing target 100 at a predetermined feed rate that is faster than the conventional feed rate, the discharge energy acting on the convex portion 12 is moderately suppressed, The build-up thickness formed in the convex part 12 is made to be comparable to the conventional build-up thickness.

  As a result of this, in the present embodiment, the processing time for build-up can be made shorter than before. In addition, since the time required for the preprocessing is considerably shorter than the time required for the build-up process, the combined time of the pretreatment and the build-up process is shorter than the time required for the conventional build-up process.

  In the present embodiment, since the feeding speed is increased as compared with the prior art, and the gap between the electrode 101 and the processing target 100 is longer by the depression of the concave portion 11, the discharge energy acting on the concave portion 11 is reduced. However, although the thickness of the built-up in the concave portion 11 (the amount of build-up) is thin (less), the function and effect as the built-up portion 102 are exhibited without problems. For example, when a cobalt-based hard alloy or a nickel-based hard alloy is used as the material of the electrode 101, the oxidation resistance that is a characteristic of these alloys can be effectively exhibited.

  As shown in FIG. 2 (b), the build-up portion 102 formed by the build-up process includes a diffusion / penetration layer 102 a in which particles of the material of the electrode 101 diffuse and penetrate from the uneven surface of the processed portion 100, The diffusion layer includes a deposition layer 102b in which particles of the material of the electrode 101 are deposited by deposition.

  The thickness of the deposited layer 102 b is thicker at the convex portion 12 and thinner at the concave portion 11 due to the difference in strength of the discharge energy acting on the concave portion 11 and the convex portion 12. Further, since the diffusion / permeation layer 102a is also affected by the discharge energy, the thickness of the diffusion / permeation layer 102a is thicker (deeper) in the convex portion 12 than in the deposited layer 102b, whereas it is thinner (shallow) in the concave portion 11. )Become.

  Since the diffusion / penetration layer 102a is formed by depositing the material of the electrode 101 on the processing target 100 by electric discharge machining, a melted portion having a gradient composition in which the composition ratio changes in the thickness direction is generated. Here, by selecting an appropriate discharge condition, the thickness of the diffusion / penetration layer 102a serving as a melting portion is 20 μm or less to limit the amount of heat input to the base material, and is 1 μm or more, preferably 5 μm or more. It is preferable to do. Since the gradient composition having the melted portion becomes a functionally gradient material, the linear expansion coefficients in the vicinity of the boundary in contact with the base material of the processed portion 100 are substantially equal, and there is almost no difference in the linear expansion coefficients. Can be eliminated. As a result, it is possible to prevent the occurrence of cracks in the built-up portion 102 applied to the surface of the processing target portion 100. The thickness of the deposited layer 102b is not limited to the thickness of the deposited layer 102b resulting from the adoption of electric discharge machining, but the thickness is not limited in order to effectively exhibit the wear resistance and oxidation resistance of the cobalt-based hard alloy. It is desirable to be about 50 μm to 300 μm.

(C) Finishing process The finishing process is shown in FIG.

  Since the upper part of the deposited layer 102b deposited on each convex part 12 is a part constituting a sliding contact surface of a product such as a valve stem, a shape suitable as a sliding contact surface by machining such as grinding or polishing. Finish flat to have dimensions and surface roughness.

  As a result of finishing in this way, not all of the surface of the deposited layer 102b becomes a slidable contact surface, but only a part of the deposited layer 102b, that is, only the upper part of the deposited layer 102b deposited on each convex portion 12 is slid. It becomes the tangent surface. Since the area of the slidable contact surface is smaller than before, friction (heat) generated in a rapidly moving valve stem or the like can be reduced, and the product life can be extended.

  In the example of FIG. 2, the case where the recesses 11 having substantially the same size are uniformly formed on the surface of the processing target 100 in the preprocessing of (a) is shown, but the present invention is not limited to this. As long as the uneven surface is formed, the size of the concave portion or the convex portion may be uneven to some extent. For example, as shown in FIG. 4 (a), the size of the recesses may be somewhat non-uniform, such as the presence of recesses 11a having different sizes from the recesses 11. In this case, the build-up process and the finishing process are the same as those described in FIGS. 2B and 2C, and the build-up process is performed as shown in FIG. Finished as shown in (c).

  In the example of FIG. 2, the case where the arc-shaped recess 11 is formed on the surface of the processing target 100 in the pre-processing of (a) is shown, but the present invention is not limited to this. As long as the uneven surface is formed, the concave portion may have a shape other than the arc shape. For example, as shown in FIG. 5A, depending on the processing means, a triangular (acute angle) recess 11b or the like may be formed. In this case, the build-up process and the finishing process are the same as those described in FIGS. 2B and 2C, and the build-up process is performed as shown in FIG. Finished as shown in (c).

  In the above description, sand blasting, shot blasting, shot peening, and WPC are exemplified as means for obtaining a textured textured surface in the pretreatment step. However, the present invention is not limited to this. . Other means may be used as long as the discharge energy from the electrode can form a concave / convex shape that acts more strongly on the convex portion than on the concave portion in the build-up process. For example, fine knurled grooves may be formed by machining, or uneven grooves and geometric patterns may be formed by chemical corrosion.

  As described above, according to the first embodiment, the processed portion is processed into a concavo-convex shape as a pretreatment for the build-up, instead of applying a uniform thickness to the entire processed portion as in the prior art. Then, a built-up portion is formed on the uneven surface after processing, and when forming the built-up portion, the electrode 101 is moved along the reference surface of the processing target portion 100 at a predetermined feed rate higher than the conventional feed rate. Therefore, the discharge energy acting on the convex portion 12 is moderately suppressed, and the build-up thickness of the convex portion 12 is approximately the same as the conventional one. can do. In addition, since the time required for the preprocessing is considerably shorter than the time required for the build-up process, the combined time of the pretreatment and the build-up process is shorter than the time required for the conventional build-up process.

  In the first embodiment, an example in which the valve rod 205 linearly moves (moves in the axial direction) with respect to the bush 201 as an example of the sliding portion has been described. However, the present invention is not limited to this. Even when the valve stem rotates (moves in the circumferential direction) like a valve, the relative relationship and structure between the valve stem and the bush are the same, and in this case, the method described in this embodiment is used. Can be applied.

[Second Embodiment]
Next, a second embodiment will be described. Here, the description of parts common to the first embodiment is omitted, and different parts are mainly described.

  FIG. 6 shows another structure of the steam control valve according to the first embodiment shown in FIG. 1, and is a partial cross-sectional view around the valve body in particular. In addition, since the basic part of the valve apparatus which concerns on 2nd Embodiment is the same as that of 1st Embodiment shown in FIG. 1, the same code | symbol is used for the component which has the same function, The description is abbreviate | omitted. . Therefore, the following description will focus on the parts that are different from the first embodiment.

  The steam control valve in FIG. 6 has a function of adjusting the steam flow rate by operating the valve rod 205 and the valve body 412 linked to the valve rod 205 in the axial direction to change the opening of the valve. In a series of operations, the valve rod 205 operates with the bush 201 installed inside the upper lid 410, and the valve body 412 operates with the sleeve 411 as a guide.

  The sleeve 411 is fixed to the upper lid 410 inside the steam valve main body 200 (not shown). The valve body 412 is provided so as to abut on a valve seat 203 (not shown), and is assembled at the tip of the valve rod 205.

  In the first embodiment shown in FIG. 1, the valve device includes a valve rod 205 as a movable member that operates as the valve is opened and closed and a bush 201 as a stationary member that is in sliding contact with the valve rod 205. In the second embodiment, a valve body 412 is applied as a movable member, and a sleeve 411 is applied as a stationary member. That is, the outer surface of the valve body 412 and the inner surface of the sleeve 411 constitute a sliding surface.

  A built-up portion 102 similar to that described in the first embodiment is integrally provided on the surface of at least one sliding contact surface of the sliding portion constituted by the valve body 412 and the sleeve 411.

  As described above, according to the second embodiment, the same effect as that of the first embodiment can be obtained even in the sliding portion in which the valve body 412 is in sliding contact with the sleeve 411.

  As described above in detail, according to each embodiment, the built-up portion can be completed in a short time, and the production efficiency can be improved.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 11 ... Concave part, 12 ... Convex part, 100 ... Processed part, 101 ... Electrode, 102 ... Overlay part, 102a ... Diffusion penetration layer, 102b ... Deposited layer, 103 ... DC power supply, 200 ... Steam valve main body, 201 ... Bush , 202 ... Upper lid, 203 ... Valve seat, 204 ... Valve body, 205 ... Valve rod, 206 ... Hydraulic drive mechanism, 207 to 209 ... Opening, 210 ... Steam chamber, 300 ... Drive mechanism, 301, 303 ... Electric motor, 302 ... Feed mechanism, 410 ... upper lid, 411 ... sleeve, 412 ... valve body.

Claims (10)

A valve device including a movable member that operates in association with opening and closing of the valve and a stationary member that is in sliding contact with the movable member,
Processing at least one surface of the movable member and the stationary member into a concavo-convex shape as a processed portion, and forming a built-up portion on the concavo-convex surface of the processed portion after processing,
The build-up portion generates a pulsed discharge between an electrode formed of a molded body containing a metal as a main component and the concavo-convex surface of the processing target portion, thereby transferring the material of the electrode to the processing target portion. A valve device formed by welding and depositing on an uneven surface.   2. The valve device according to claim 1, wherein the uneven surface of the portion to be processed is a finish obtained by mechanically processing the surface of the portion to be processed.   3. The valve device according to claim 1, wherein the uneven surface of the processing portion is a finish made by mechanically roughening the surface of the processing portion.   The uneven surface of the to-be-processed part is formed by performing a blasting process or a peening process on the surface of the to-be-processed part. The valve device described.   Among the built-up parts formed on the uneven surface of the treated part, the thickness of the built-up part formed on the concave surface is thinner than the thickness of the built-up part formed on the convex surface The valve device according to any one of claims 1 to 4, characterized in that:   The build-up portion includes a diffusion / penetration layer in which particles of the electrode material are diffused and permeated from the concavo-convex surface of the processed portion, and a deposition layer in which particles of the electrode material are deposited on the diffusion / penetration layer. The valve device according to any one of claims 1 to 5, characterized by comprising: The oxide film containing chromium carbide (CrC) or chromium oxide (Cr ₂ O ₃ ) is formed on the concave surface of the processing target part. Valve device.   8. The valve device according to claim 1, wherein the movable member includes a valve stem, and the stationary member includes a bush slidably contacting the valve rod.   The valve device according to any one of claims 1 to 8, wherein the movable member includes a valve body, and the stationary member includes a sleeve that is slidably contacted with the valve body. A method of manufacturing a valve device including a movable member that operates in accordance with opening and closing of the valve and a stationary member that is in sliding contact with the movable member,
Processing at least one surface of the movable member and the stationary member into a concavo-convex shape as a treated portion;
Forming a build-up part on the uneven surface of the processed part processed;
Including
In the step of forming the build-up portion, a pulsed discharge is generated between an electrode constituted by a molded body containing metal as a main component and the concavo-convex surface of the treated portion, and the material of the electrode is A method for manufacturing a valve device, comprising forming a build-up portion by welding and depositing on an uneven surface of a portion to be processed.