JP2017196623A - Manufacturing method of valve device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a valve device capable of reducing a leakage quantity of steam, by preventing the occurrence of a stick in a movable member.SOLUTION: A manufacturing method of the present embodiment manufactures a valve device of including a movable member and a stationary member for storing its movable member on the inside and mutually slidingly contacting the movable member and the stationary member in response to opening-closing operation. This manufacturing method comprises a build-up part forming process of forming a build-up part on at least one sliding contact surface of the movable member and the stationary member. In the build-up part forming process, the build-up part is formed by finishing by executing laser build-up welding on a surface of its spiral build-up part after forming a spiral build-up part by executing the laser build-up welding in a spiral shape toward the other end from one end in the sliding contact surface.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a method for manufacturing a valve device.

  In the steam turbine plant, valve devices such as a main steam stop valve, a steam control valve, a reheat steam stop valve, and an intermediate stop valve are installed. These valve devices are used under severe steam conditions of high temperature and pressure, and control high-speed steam flow.

  A steam control valve 20 will be described with reference to FIG. 14 as an example of a valve device installed in a steam turbine plant.

  As shown in FIG. 14, the steam control valve 20 has a valve body 204 installed at one end of a valve rod 205 housed inside the steam valve body 200, and a valve seat 203 inside the steam valve body 200. is set up.

  Specifically, in the steam control valve 20, the steam valve main body 200 is a valve casing, and a steam chamber 300 (valve chamber) is provided therein. The steam chamber 300 is provided with an inlet portion 301 and an outlet portion 302. In the steam valve main body 200, the inlet portion 301 is provided on the side of the steam chamber 300, and the outlet portion 302 is provided below the steam chamber 300. Here, the tubular portion in which the inlet portion 301 is formed in the steam valve main body 200 is cylindrical, and the tube axis is along the horizontal direction. And the tubular part in which the exit part 302 was formed in the steam valve main body 200 is cylindrical shape, and the pipe axis is along the perpendicular direction.

  In addition, the steam valve main body 200 has an opening 303 formed above the steam chamber 300, and a valve lid 202 is installed so as to close the opening 303. The valve lid 202 has a through-hole 202K formed at the center. The through hole 202K of the valve lid 202 has a hole axis along the vertical direction, and a cylindrical bush 201 penetrates and is fixed inside the through hole 202K of the valve lid 202.

  The valve seat 203 is fixed to the inner peripheral surface of the tubular portion in which the outlet portion 302 is formed in the steam valve main body 200. The valve seat 203 is, for example, a ring-shaped tubular body, and is disposed so as to be coaxial with the valve stem 205.

  The valve body 204 is connected to the valve rod 205 inside the steam chamber 300. Here, the valve body 204 has a hemispherical shape, for example, and is installed so as to be coaxial with the valve stem 205.

  The valve stem 205 is accommodated in the bush 201 and is installed in the valve lid 202 so as to penetrate the through hole 202K of the valve lid 202 via the bush 201. The valve stem 205 is, for example, a cylindrical rod-like body, the axis is along the vertical direction, and the valve body 204 is installed at the lower end of the valve rod 205. The valve stem 205 is a movable member that moves in accordance with the opening / closing operation of the steam control valve 20. When the steam control valve 20 is opened / closed, the outer peripheral surface of the valve rod 205 and a bush that is a stationary member are used. The inner peripheral surfaces of 201 are in sliding contact with each other.

  In addition to the above-described configuration, the steam control valve 20 has a hydraulic drive mechanism 206 connected to the upper end of the valve rod 205. The hydraulic drive mechanism 206 moves the valve rod 205 along the vertical direction. Thereby, in the steam control valve 20, the distance between the valve body 204 and the valve seat 203 fluctuates, the opening degree is adjusted, and the flow of steam is controlled. When opening the steam control valve 20, the hydraulic drive mechanism 206 moves the valve rod 205 upward in the vertical direction to separate the valve body 204 and the valve seat 203, so that the inlet 301 of the steam valve main body 200 can be opened. The inflowing steam F flows through the steam chamber 300 and is discharged from the outlet portion 302 of the steam valve main body 200. On the other hand, when the steam control valve 20 is closed, the hydraulic drive mechanism 206 moves the valve rod 205 downward in the vertical direction, so that the valve body 204 contacts the valve seat 203 and the flow of the steam F is stopped. It is done.

  In the valve device such as the steam control valve 20 described above, the metal surface of the base material is activated by high-temperature steam as compared with the case of room temperature, and an oxide film (oxide scale) is generated. The generated oxide film has different mechanical adhesion strength depending on the composition of the base material and the conditions of the atmosphere. For this reason, when the opening / closing operation is performed in the valve device, the oxide film is peeled off. As a result, the peeled oxide film fills the space between the movable member such as the valve stem 205 and the stationary member such as the bush 201, and a stick (a phenomenon in which the valve stem 205 sticks to the bush 201) occurs. There is a case. Therefore, it is necessary to remove the oxide film when performing periodic inspection on the steam turbine.

  Further, when the amount of deposited oxide film is estimated in advance and the gap between the valve stem 205 and the bush 201 is increased, the amount of steam leakage increases. In particular, in recent years, steam supplied as a working fluid to a steam turbine has a tendency to increase in temperature and pressure, so that the amount of steam leaking from the gap between the valve stem 205 and the bush 201 is further increased. The thermal efficiency of the whole plant deteriorates.

  Conventionally, a nitrided layer is provided as a hardened surface layer by performing nitriding on the outer peripheral surface of the valve stem 205 and the inner peripheral surface of the bush 201. However, the nitride layer decomposes and softens at about 500 ° C. or higher. The nitride layer is extremely thin. For this reason, when the nitride layer disappears due to wear, the wear progresses rapidly.

  In order to cope with the above problems, it is proposed to form a built-up portion such as a cobalt-based hard alloy as a hard alloy layer on the sliding contact surface of the valve rod 205 that contacts the bush 201 during the opening / closing operation of the valve device. Has been. When forming a built-up part such as a cobalt-based hard alloy by a method such as an oxygen acetylene method, a TIG (Tungsten Inert Gas) method, a covered arc method, or a PTA (Plasma Transferred Arc) method, Since the amount of heat input (heating amount) is large, the valve stem 205 may be greatly deformed. For this reason, it has been proposed to form a built-up portion such as a cobalt-based hard alloy by performing laser powder build-up welding with a small amount of heat input (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 06-174126

  As shown in FIG. 15, when the built-up portion 22 is formed on the sliding contact surface of the valve stem 205, the laser spirals from one end side (left side in FIG. 15) to the other end side (right side) of the valve stem 205. Perform powder overlay welding.

  Specifically, when performing laser powder overlay welding, for example, the center axis of the valve stem 205 is rotated relative to a welding torch (not shown) about the rotation center. At the same time, the valve stem 205 is moved relative to the welding torch from the other end side (right side) toward the one end side (left side) in the direction along the central axis of the valve stem 205. At this time, for example, a powder of a built-up material such as a hard alloy is continuously supplied to the outer peripheral surface of the valve stem 205 from a powder supply device (not shown), and a laser beam is applied to the hard alloy powder from a welding torch. Irradiating continuously, the powder of the cladding material is melted. The overlay material is rapidly cooled and solidified. Thereby, in the valve stem 205, the build-up portion 22 is formed so as to draw a spiral from the welding start point 22S to the welding end point 22E.

  However, in the above related art, a crater-like recess may be formed as a defect at the welding end point 22E where the laser powder overlay welding is completed, and solidification cracks may occur in the recess. Specifically, the crater-shaped recess (melting pool) at the welding end point 22E includes both components of the overlay material and the material of the valve stem 205 different from the overlay material. When the laser beam irradiation is cut off at the welding end point 22E, the temperature rapidly decreases at the welding end point 22E. For this reason, stress concentrates in the concave portion due to shrinkage due to solidification, and solidification cracks occur. As a result, the quality of the build-up part 22 may become unstable. In particular, when a cobalt base hard alloy is used as a build-up material, the ductility of the cobalt base hard alloy is generally lower than that of the material of the valve stem 205, and thus the above problem becomes obvious.

  Due to the above circumstances, it may not be easy to prevent sticks from being generated in a movable member such as a valve stem, and it may be difficult to reduce the amount of steam leakage.

  Therefore, the problem to be solved by the present invention is that it is possible to stabilize the quality of the built-up portion, prevent sticks from being generated in movable members such as valve stems, and reduce the amount of leakage of steam. It is to provide a method for manufacturing a valve device.

  In the manufacturing method of the embodiment, a valve device that includes a movable member and a stationary member that accommodates the movable member therein, and in which the movable member and the stationary member are in sliding contact with each other in accordance with the opening / closing operation is manufactured. The manufacturing method includes a build-up portion forming step of forming a build-up portion on at least one sliding contact surface of the movable member and the stationary member. In the build-up portion forming step, laser build-up welding is performed spirally from one end to the other end on the sliding contact surface to form a spiral build-up portion, and then laser build-up is performed on the surface of the helical build-up portion. A build-up part is formed by completing the build-up welding.

FIG. 1 is a perspective view showing an outline when the built-up portion 22 is formed on the sliding contact surface of the valve rod 205 in the first embodiment. FIG. 2 is a perspective view showing an outline when the built-up portion 22 is formed on the sliding contact surface of the valve stem 205 in the first embodiment. FIG. 3 is a cross-sectional view showing an outline of a welding torch of a welding apparatus used when performing laser powder overlay welding in the first embodiment. FIG. 4 is a cross-sectional view showing an outline when the built-up portion 22b is formed on the sliding contact surface of the valve stem 205 in the second embodiment. FIG. 5 is a perspective view showing an outline when the built-up portion 22b is formed on the sliding contact surface of the valve rod 205 in the second embodiment. FIG. 6 is a perspective view showing an outline when the built-up portion 22b is formed on the sliding contact surface of the valve rod 205 in the second embodiment. FIG. 7 is a diagram illustrating the second buildup part 222 constituting the buildup part 22b in the second embodiment. FIG. 8 is a diagram illustrating the second buildup part 222 constituting the buildup part 22b in the modification of the second embodiment. FIG. 9 is a diagram illustrating the second build-up portion 222 that constitutes the build-up portion 22b in the modification of the second embodiment. FIG. 10 is a cross-sectional view showing an outline when the built-up portion 22b is formed on the sliding contact surface of the valve rod 205 in the modification of the second embodiment. FIG. 11 is a cross-sectional view showing an outline when the built-up portion 22b is formed on the sliding contact surface of the valve stem 205 in the modification of the second embodiment. FIG. 12 is a cross-sectional view showing an outline when the built-up portion 22c is formed on the sliding contact surface of the valve stem 205 in the third embodiment. FIG. 13 is a perspective view showing an outline when the built-up portion 22c is formed on the sliding contact surface of the valve rod 205 in the third embodiment. FIG. 14 is a cross-sectional view schematically showing a valve device in a steam turbine plant according to related technology. FIG. 15 is a perspective view showing a state when the built-up portion 22 is formed on the valve stem 205 in the related art.

<First Embodiment>
A state when the built-up portion 22 is formed on the sliding contact surface of the valve rod 205 in the first embodiment will be described with reference to FIGS. 1 and 2.

  When forming the built-up portion 22, first, as shown in FIG. 1, as in the related art (see FIG. 15), on the outer peripheral surface of the valve stem 205, spirally from one end to the other end. The helical build-up layer portion 41 is formed by performing laser powder build-up welding, but in the present embodiment, unlike the related art, after the helical build-up layer portion 41 is formed, the helical build-up layer portion 41 is formed. By performing laser powder overlay welding continuously on the surface of the overlay layer portion 41, the linear overlay layer portion 42 is formed.

  Specifically, the linear build-up layer portion 42 is configured so that the laser powder returns linearly from the other end side (right side) of the valve stem 205 to the one end side (left side) on the surface of the spiral build-up layer portion 41. After the body build-up welding, the laser powder build-up welding is completed on the surface of the spiral build-up layer portion 41. For example, the linear build-up layer portion 42 is formed by ending the laser powder build-up welding at a position where it has returned by two to three turns from the last turn formed in the spiral build-up layer portion 41. Is done. In the present embodiment, the linear built-up layer portion 42 is formed so as to extend along the axial direction of the valve stem 205.

  Thus, the build-up portion 22 is formed so that the build-up portion 22 further includes the linear build-up layer portion 42 together with the spiral build-up layer portion 41. In the present embodiment, a crater-like recess is formed at the welding end point 22E where the laser powder build-up welding is completed in the formation of the build-up portion 22 as in the related art. However, in the present embodiment, unlike the related technology, the molten pool formed at the welding end point 22E does not include the material of the valve stem 205 different from the overlay material. For this reason, even if it is a case where irradiation of a laser beam is interrupted | blocked at the welding end point 22E and the temperature of the welding end point 22E falls rapidly, it can suppress that stress concentrates on a recessed part. As a result, in this embodiment, the occurrence of solidification cracks can be prevented, and the quality of the build-up portion 22 can be stabilized.

  After the build-up portion 22 is formed as shown in FIG. 1, a finishing process for planarizing the surface of the build-up portion 22 is performed as shown in FIG. In the finishing process, the polishing process and the grinding process are performed on the surface of the built-up portion 22 so as to obtain preset dimensions, geometrical tolerances, surface roughness, and the like.

  As described above, in the present embodiment, since the build-up portion 22 is formed by laser powder build-up welding with a small amount of heat input, deterioration and deformation of the valve stem 205 can be effectively suppressed. Moreover, since the build-up portion 22 is formed so as to cover the outer peripheral surface of the valve stem 205 using a material having high oxidation resistance, it is inexpensive and effective that an oxide film is generated on the outer peripheral surface of the valve stem 205. Can be prevented. As a result, sticking can be prevented from occurring in the valve stem 205, and the gap between the valve stem 205 and the bush 201 can be reduced, so that the amount of steam leakage can be reduced.

  In this embodiment, when performing the above-described laser powder overlay welding, for example, a welding apparatus (not shown) provided with a welding torch 10 shown in FIG. 3 is used.

  In the welding torch 10, a laser irradiation port 11, a powder supply path 12, a shield gas supply path 16, and a cooling water circulation path 18 are formed in the torch body 100.

  In the welding torch 10, the torch body 100 has a truncated cone shape on the tip side.

The laser irradiation port 11 is formed along the central axis of the torch body 100. The laser irradiation port 11 is irradiated with a laser beam LA (laser light) emitted from a laser device such as a semiconductor laser, a YAG laser, a fiber laser, or a CO ₂ laser through the inside and irradiated from the tip.

  The powder supply path 12 is formed coaxially with the laser irradiation port 11 so as to surround the laser irradiation port 11 in the torch body 100. In the powder supply path 12, the powder PA of the cladding material (coating material) passes through the inside together with the carrier gas and is sprayed from the tip, and is supplied to the outer peripheral surface (the upper surface in FIG. 3) of the valve stem 205 as the base material. . The build-up material powder PA is melted by the laser beam LA irradiated from the laser irradiation port 11 on the outer peripheral surface of the valve rod 205 and then cooled and solidified to form the build-up portion 22.

  The shield gas supply path 16 is formed coaxially with the laser irradiation port 11 so as to surround the powder supply path 12 in the torch body 100. In the shield gas supply path 16, the shield gas SG passes through the inside and is injected from the tip. The shield gas SG is argon gas or the like, and is injected from the shield gas supply path 16 in order to suppress oxidation of the buildup portion 22 and the periphery of the buildup portion 22.

  The cooling water circulation path 18 is formed coaxially with the laser irradiation port 11 so as to surround the shield gas supply path 16 in the torch body 100. The cooling water circulation path 18 circulates cooling water (not shown) inside. The cooling water is supplied to the cooling water circulation path 18 in order to cool the torch body 100 heated by the irradiation of the laser beam LA.

  In the welding apparatus, the welding torch 10 is connected to a robot arm (not shown), and the valve rod 205 is supported by a rotating device. And in a welding apparatus, laser powder build-up welding (refer FIG. 1) is implemented as mentioned above, when a control apparatus controls operation | movement of a robot arm and operation | movement of a rotation apparatus.

  In the laser powder overlay welding, the powder PA of the overlay material (coating material) and the laser beam LA are irradiated on the concentric shaft from the tip side portion of the welding torch 10. Since the powder PA passes through the inside together with the carrier gas and is sprayed from the tip, the powder PA of the overlaying material falls by its own weight and is not supplied to the sliding contact surface of the valve stem 205. Further, in the welding apparatus, the tip side portion of the welding torch 10 is directed in all directions by the robot arm. That is, the welding torch 10 is directed upward and laterally in addition to the tip side portion facing downward. For this reason, in this embodiment, the welding posture when performing laser powder overlay welding is not limited.

  The overlaying material powder PA used in the above laser powder overlay welding will be described. The overlaying material powder PA is, for example, a cobalt-based hard alloy (Stellite (registered trademark), etc.) excellent in wear resistance. Specifically, the powder PA of the cladding material is a cobalt-based hard alloy containing cobalt as a main component and containing about 30 wt% chromium and 4 to 15 wt% tungsten as components. Since the cobalt-based hard alloy has higher oxidation resistance than the base material such as the valve stem 205, an oxide film (oxide scale) is hardly generated under conditions where steam is at a high temperature. For this reason, it is not necessary to increase the gap between the valve stem 205 and the bush 201 (see FIG. 14) in anticipation of the amount of oxide film (oxide scale) generated, so that the leakage of steam to the outside through this gap. The amount can be reduced.

  In addition to the above, the material PA for the build-up material can use a material having an oxidation start temperature of 800 ° C. or higher and excellent in oxidation resistance. For example, chromium nitride (CrN), titanium aluminum nitride (TiAlN), titanium tungsten nitride (Ti-W) N, titanium carbide (Ti-Mo) C, chromium silicon nitride (CrSiN), and titanium silicon nitride (TiSiN) Or the like can be suitably used as the powder PA of the overlaying material. Further, the fine ceramic powder and the cobalt-based hard alloy described above may be mixed. Furthermore, a powder of a new material that will be developed as the steam temperature rises in the future may be used as the powder PA of the cladding material.

  The powder PA of the cladding material has a powder particle size of 1 μm or more, and preferably 30 to 100 μm. Thereby, it is possible to suppress the powder PA of the overlay material from being scattered by the shield gas SG ejected from the shield gas supply path 16.

  The base material such as the valve stem 205 on which the laser powder overlay welding is performed is, for example, chromium-molybdenum steel, chromium-molybdenum-vanadium steel, chromium-molybdenum-tungsten-vanadium steel, 9% chromium steel, It is a metal material such as 12% chromium steel, Ni-base or Co-base heat-resistant alloy. In addition, as the base material, a heat-resistant alloy steel made of any of ferrite, martensite, and austenite can be used. Furthermore, a new material that will be developed in the future as the steam temperature rises may be used as the base material.

  In the present embodiment, the case where the built-up portion 22 is formed on the outer peripheral surface of the cylindrical valve rod 205 is described. However, the built-up portion 22 is formed on the inner peripheral surface of the cylindrical bush 201. It is also possible (the same applies to other embodiments described later).

  In addition, in the case of a valve device configured such that a sleeve (not shown) as a stationary member accommodates the valve body 204 as a movable member inside, the outer peripheral surface of the valve body 204 and the inner peripheral surface of the sleeve. As in the above, the built-up portion 22 may be formed on at least one of (and other embodiments to be described later).

Second Embodiment
The built-up portion 22 formed on the sliding contact surface of the valve stem 205 in the second embodiment will be described with reference to FIGS.

  In the present embodiment, as shown in FIG. 4, the build-up part 22 b includes a first build-up part 221 and a second build-up part 222, and the second build-up part 222 is a valve on the first build-up part 221. The rod 205 is provided so as to protrude in a radial direction (vertical direction in FIG. 4).

  In this embodiment, when forming the build-up portion 22b, first, the first build-up portion 221 is formed as shown in FIG. The first build-up portion 221 is subjected to a finishing process for planarizing the surface after laser powder build-up welding, as in the case of the build-up portion 22 (see FIG. 2) of the first embodiment. Formed with. In the finishing process, a polishing process and a grinding process are performed on the surface of the first build-up portion 221 so as to obtain preset dimensions, geometrical tolerances, surface roughness, and the like.

  Then, as shown in FIGS. 6 and 7, after the formation of the first build-up part 221, the second build-up part 222 is formed. The second build-up part 222 is formed into a geometric pattern by performing laser powder build-up welding on the surface of the first build-up part 221.

  The geometric pattern of the second build-up portion 222 is, for example, a pattern in which a plurality of regular square patterns are arranged in each of the axial direction (lateral direction in FIG. 7) and the circumferential direction (vertical direction) of the valve stem 205. is there. Here, the four walls constituting the regular tetragonal pattern are not along the axial direction and the circumferential direction of the valve stem 205, and each is inclined. Further, the four walls constituting the regular square pattern are connected to each other in the axial direction and the circumferential direction of the valve stem 205.

  In the welding apparatus, the second overlaying part 222 appropriately changes the rotation direction of the valve stem 205 to the forward direction and the reverse direction, and the robot arm controls the position of the welding torch 10 to perform laser powder overlay welding. It is formed by carrying out. The second build-up portion 222 is subjected to finishing after performing laser powder build-up welding. That is, the polishing process and the grinding process are performed on the outer peripheral surface of the second build-up portion 222 so as to have preset dimensions, geometrical tolerances, and surface roughness.

  As described above, in the valve device according to the present embodiment, the valve rod 205 has a concave portion formed on the outer peripheral surface side by the second overlaying portion 222 having a geometric pattern. The recessed part by the 2nd overlaying part 222 of a geometric pattern functions as a labyrinth seal. For this reason, in this embodiment, the quantity of the vapor | steam leaking from between the column-shaped valve rod 205 and the cylindrical bush 201 can be reduced effectively.

  Specifically, when the steam flowing between the valve stem 205 and the bush 201 flows into the concave portion formed by the second overlaying portion 222 having a geometric pattern, the pressure expands and the pressure decreases. And when the vapor | steam flows out from a recessed part, since a flow path is narrow, a pressure rises. For this reason, the steam flowing between the valve stem 205 and the bush 201 causes a large pressure loss due to the second overlaying portion 222 having a geometric pattern. Therefore, as described above, in this embodiment, the amount of steam leakage can be effectively reduced.

  In addition, in this embodiment, when the oxide film deposited on the outer surface of the valve stem 205 is peeled off, the oxide film is accommodated in the recess by the second overlaying part 222 having a geometric pattern. For this reason, it can prevent effectively that a stick generate | occur | produces in the valve stem 205 resulting from an oxide film.

  The thickness of the second build-up portion 222 is preferably, for example, 50 μm or more. By increasing the thickness of the second build-up portion 222, the volume of the recess formed by the second build-up portion 222 is increased, so that the ratio of reducing the pressure of the leaking steam can be increased.

  The geometric pattern of the second build-up portion 222 may be, for example, the patterns shown in FIGS. 8 and 9 in addition to the pattern shown in FIG. Specifically, as shown in FIG. 8, the geometric pattern of the second build-up portion 222 may be a pattern in which circular patterns are arranged in a staggered manner in the axial direction and the circumferential direction of the valve rod 205. As shown in FIG. 9, the geometric pattern of the second build-up portion 222 may be a pattern in which square patterns are arranged in a staggered manner in the axial direction and the circumferential direction of the valve rod 205. The pattern shown in FIG. 8 and FIG. 9 is connected in the circumferential direction of the valve stem 205 and functions as a fluid resistance, like the pattern shown in FIG.

  Moreover, it is suitable for the shape of the cross section cut | disconnected in the radial direction of the valve stem 205 about the 2nd build-up part 222 to the shape shown in FIG. 10 other than the shape shown in FIG. Specifically, the second build-up portion 222 has a shape in which a flange portion 222H is formed at the tip of the convex portion 222T.

  In the second build-up portion 222, the convex portion 222T is a portion protruding from the surface of the first build-up portion 221 in the radial direction of the valve rod 205.

  The flange 222H is a portion protruding in the axial direction of the valve stem 205, and is formed so that the inner peripheral surface of the flange 222H faces the outer peripheral surface of the first build-up portion 221 with a gap (bag portion) therebetween. Has been. Here, the flange 222H protrudes toward the side where the valve body 204 is provided in the valve rod 205 (see FIG. 14). In other words, the flange 222H protrudes upstream in the flow of steam leaking from the steam chamber 300 (high pressure side) to the outside (low pressure side) through the space between the valve rod 205 and the bush 201. In the present embodiment, a gap is interposed between the inner peripheral surface of the flange portion 222H of the second build-up portion 222 and the outer peripheral surface of the first build-up portion 221, and therefore, between the valve stem 205 and the bush 201. The second build-up portion 222 has an even greater fluid resistance against the flow of steam leaking from. As a result, the amount of steam leaking from between the valve stem 205 and the bush 201 can be further effectively reduced.

  In particular, in the present modification, the flange 222H has a shape with a sharp tip. Here, the flange 222H is formed such that a distance protruding in the axial direction of the valve rod 205 becomes longer from the inner peripheral side toward the outer peripheral side. Thereby, the fluid resistance can be further increased.

  In addition to the above, the cross-sectional shape of the second build-up portion 222 may be, for example, an arc shape, and similar actions and effects can be obtained.

  In addition to the above, the build-up portion 22b may integrally form the first build-up portion 221 and the second build-up portion 222 as shown in FIG. That is, you may shape | mold about both the 1st build-up part 221 and the 2nd build-up part 222 by performing laser powder build-up welding continuously at once. Each of the first build-up portion 221 and the second build-up portion 222 is subjected to polishing and grinding so as to have preset dimensions, geometrical tolerances, surface roughness, and the like. In this case, the surface of the first build-up portion 221 does not need to be ground.

<Third Embodiment>
The built-up portion 22c formed on the sliding contact surface of the valve stem 205 in the third embodiment will be described with reference to FIGS.

  In the present embodiment, as shown in FIGS. 12 and 13, the built-up portion 22 c performs laser powder build-up welding on the outer peripheral surface of the valve stem 205, similarly to the second built-up portion 222 of the second embodiment. By doing so, a geometric pattern is formed. The build-up portion 22c is subjected to polishing and grinding so as to have preset dimensions, geometric tolerances, surface roughness, and the like.

  In this embodiment, since the overlaying portion 22c is formed in a geometric pattern, the steam leaking from between the columnar valve rod 205 and the cylindrical bush 201 is the same as in the second embodiment. The amount can be effectively reduced.

  In the present embodiment, since the base material of the valve stem 205 is exposed at the bottom surface of the concave portion formed by the geometrically built-up portion 22c, an oxide film is easily generated and deposited. For this reason, it is preferable to determine the thickness of the build-up portion 22c in consideration of the expected thickness of the oxide film.

  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.

  For example, in each of the above embodiments, the build-up portion is formed so that the build-up portion is raised on the outer peripheral surface of the valve stem, but this is not a limitation. After performing the process of forming a groove on the outer peripheral surface of the valve stem, the overlay portion may be formed so as to fill the groove. Here, the groove is processed so that the depth of the groove corresponds to the thickness of the built-up portion.

  Moreover, in each said embodiment, although the build-up part is formed by performing laser powder build-up welding, it is not restricted to this. In addition to the powder build-up material, the build-up portion may be formed by performing laser build-up welding using a build-up material of another shape such as a bar shape.

DESCRIPTION OF SYMBOLS 10 ... Welding torch, 11 ... Laser irradiation port, 12 ... Powder supply path, 16 ... Shield gas supply path, 18 ... Cooling water circulation path, 20 ... Steam control valve, 22 ... Overlay part, 22b ... Overlay part, 22c ... Build-up part, 41 ... spiral build-up layer part, 42 ... linear build-up layer part, 100 ... torch body, 200 ... steam valve body, 201 ... bush, 202 ... valve lid, 202K ... through hole, 203 ... valve Seat, 204 ... Valve body, 205 ... Valve rod, 206 ... Hydraulic drive mechanism, 221 ... First build-up part, 222 ... Second build-up part, 222H ... Gutter part, 222T ... Projection part, 300 ... Steam chamber, 301 ... Inlet part 302 ... Outlet part 303 ... Opening F ... Vapor, LA ... Laser beam, PA ... Powder, SG ... Shield gas

Claims (6)

A manufacturing method of a valve device including a movable member and a stationary member that accommodates the movable member therein, wherein the movable member and the stationary member are in sliding contact with each other in accordance with an opening / closing operation,
Forming a built-up part on at least one sliding contact surface of the movable member and the stationary member;
In the build-up portion forming step, after forming the helical build-up portion by performing laser build-up welding spirally from one end to the other end on the sliding contact surface, on the surface of the helical build-up portion Forming the build-up part by ending the laser build-up welding,
A method for manufacturing a valve device. In the build-up portion forming step, the laser build-up welding is finished after performing the laser build-up welding so as to return linearly from the other end side to the one end side on the surface of the spiral build-up portion. By forming the build-up part,
The manufacturing method of the valve apparatus of Claim 1. A manufacturing method of a valve device including a movable member and a stationary member that accommodates the movable member therein, wherein the movable member and the stationary member are in sliding contact with each other in accordance with an opening / closing operation,
A build-up part forming step of forming a build-up part on at least one sliding contact surface of the movable member and the stationary member;
The build-up part forming step includes
After the laser build-up welding is performed spirally from one end to the other end on the sliding contact surface to form a spiral build-up portion, the laser build-up welding is performed on the surface of the spiral build-up portion. A first build-up portion forming step of forming a first build-up portion by ending,
Processing the surface of the first build-up portion, surface processing step forming the second build-up portion in a geometric pattern by performing laser build-up welding on the surface processed in the first build-up portion, Including a second build-up part forming step,
A method for manufacturing a valve device. The second overlay is
Including a flange protruding toward the upstream side of the fluid leaking between the movable member and the stationary member,
The manufacturing method of the valve apparatus of Claim 3. A manufacturing method of a valve device including a movable member and a stationary member that accommodates the movable member therein, wherein the movable member and the stationary member are in sliding contact with each other in accordance with an opening / closing operation,
A build-up part forming step of forming a build-up part on at least one sliding contact surface of the movable member and the stationary member;
In the build-up portion forming step, the build-up portion includes a first build-up portion formed on the sliding contact surface and a second build-up portion formed in a geometric pattern on the surface of the first build-up portion. So as to form the build-up portion by performing laser build-up welding on the sliding contact surface,
A method for manufacturing a valve device. A manufacturing method of a valve device including a movable member and a stationary member that accommodates the movable member therein, wherein the movable member and the stationary member are in sliding contact with each other in accordance with an opening / closing operation,
A build-up part forming step of forming a build-up part on at least one sliding contact surface of the movable member and the stationary member;
In the overlay part forming step, the overlay part is formed into a geometric pattern by performing laser overlay welding on the sliding surface.
A method for manufacturing a valve device.

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