Common jig for repairing weld zone and lapping contact face, and use method thereof

Abstract

To provide a common jig for repairing a weld zone and lapping a contact faces, which enables the reduction of a lead time and a production cost, making use of advantages such as the fast speed of repair by welding and the excellent strength of a repaired portion.SOLUTION: A common jig 1 for repairing a weld zone and lapping a contact face, comprises: a jig body 3 having a shape rotationally symmetrical around a center axis, with a section thereof capable of tightly adhering to the weld zone, i.e., a lapping object of a valve seat 4 or a seat surface of a main valve, formed across a circumferential direction; and a plating mechanism having a writing brush 7 for plating installed at the jig body 3 and a chemical liquid feed line connected to the writing brush 7, and forming a plating layer on a plating object in an installed state without disassembling the valve seat 4 or the main valve.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a common jig for repairing welded portions and lapping contact surfaces, and a method of using the same. [Background technology]

[0002] During periodic inspections of power plants, surface defects may be found on the stellite welds on the main valves and valve seat surfaces of steam turbine control valves.If the surface defects exceed the judgment value, replacement with a new one is recommended, but welding repair of the stellite part may be performed depending on customer needs.

[0003] When repairing surface defects or correcting shapes by welding, setting appropriate construction conditions can give the repaired area strength characteristics equal to or even greater than before the repair. However, repairs by welding are characterized by the application of heat to the item being repaired. When heat is applied locally to the item being repaired, thermal strain occurs, and residual stress occurs as the thermal strain accumulates inside the material. If the residual stress is not acceptable for the product design, the residual stress must be removed by full-body annealing, in which the item is placed in a heating furnace and held at a uniformly high temperature. Furthermore, full-body annealing can cause surface oxidation and thermal deformation, which may require correction processing on previously processed surfaces, posing the issue of significantly increasing costs and lead time (LT).

[0004] In contrast, nickel or chromium plating is sometimes used to repair areas requiring wear and corrosion resistance. For example, chromium plating can form a very dense and hard coating, making it often used to repair areas requiring wear resistance. Meanwhile, nickel plating is widely used due to its high corrosion resistance and excellent adhesion to a variety of materials. Plating is suitable for spot repairs because it does not cause thermal distortion. Furthermore, brush plating technology allows for the application of simple equipment, eliminating the need for pools of chemicals required for tank plating. This allows for on-site application, potentially reducing costs and lead times (LT). While the above repair work is typically performed during power plant periodic inspections, the need to shorten inspection periods in recent years has created a strong demand for repair techniques that can be easily performed within the plant. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-186892 [Patent Document 2] Special Publication No. 2005-530926 [Patent Document 3] Japanese Patent Publication No. 2022-084341 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem that the present invention aims to solve is to provide a common jig for repairing welded parts and lapping contact surfaces, which makes it possible to reduce lead time and manufacturing costs while taking advantage of the advantages of high speed repair by welding and excellent strength of the repaired area, and a method for using the same. [Means for solving the problem]

[0007] The common jig for repairing welded parts and lapping contact surfaces in this embodiment has a jig body that has a rotationally symmetric shape around a central axis and has a portion formed around the circumferential direction that can come into close contact with the welded part that is the object of lapping on the seat surface of the valve seat or main valve, and a plating mechanism that has a plating brush attached to the jig body and a chemical solution supply line connected to the brush, and that forms a plating layer on the object of plating while the valve seat or main valve is in an installed state without disassembling it. [Effects of the Invention]

[0008] According to the embodiment of the common jig for repairing welded parts and lapping contact surfaces, plating repair and lapping processing of the valve seat or the seat surface of the main valve can be carried out sequentially, making it possible to reduce lead time and manufacturing costs while taking advantage of the advantages of fast repair speed by welding and excellent strength of the repaired area. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 10 is a cross-sectional view showing a common jig for repairing welded portions and lapping contact surfaces in an embodiment. [Figure 2] FIG. 2 is a diagram showing a plating mechanism of the common jig shown in FIG. [Figure 3] 10 is a flowchart showing a process of repairing a welded portion and a process of lapping contact surfaces using a common jig according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The common jig for repairing welded portions and lapping contact surfaces and its method of use will be described below with reference to the drawings. In each embodiment, substantially identical components are designated by the same reference numerals, and some of their descriptions may be omitted. The drawings are schematic, and the relationship between the thickness of each component and the planar dimensions, the thickness ratio of each component, etc. may differ from the actual ones.

[0011] Figure 1 is a cross-sectional view showing a common jig for repairing welds and smoothing contact surfaces according to an embodiment. The common jig for repairing welds and smoothing contact surfaces (hereinafter abbreviated as common jig) 1 shown in Figure 1 is used to repair surface defects present in welds by covering them with plating, and to smooth the contact surfaces of the parts repaired by plating. The common jig 1 shown in Figure 1 has a common jig main body 3 that is attached to a casing main body 2 of a control valve of a steam turbine, for example. A valve seat 4 is provided within the casing main body 2, and the common jig main body 3 is used by being installed on the valve seat 4.

[0012] The common jig body 3 has a shape that is rotationally symmetrical about the central axis, and has a portion formed in the circumferential direction that can come into close contact with the welded portion, which is the target of lapping the seating surface of the valve seat 4. The welded portion, which is the target of lapping the seating surface of the valve seat 4, will be described in detail later. The outer periphery of the common jig body 3 that can come into close contact with the welded portion has a shape that faces and corresponds to the shape of the seating surface of the valve seat 4. The common jig body 3 is connected to a handle 6 via a shaft 5. By rotating the handle 6, the outer periphery of the common jig body 3 is brought into contact with the seating surface of the valve seat 4. Therefore, by sandwiching paper or the like between the outer periphery of the common jig body 3 and the seating surface of the valve seat 4, the seating surface of the valve seat 4 can be lapped by rotating the common jig body 3 in the circumferential direction.

[0013] The common jig body 3 is provided with a plating brush (brush plating tool) 7. As shown in FIG. 2, the brush plating tool 7 is disposed in a through-hole 8 provided in the common jig body 3 toward the seating surface of the valve seat 4. Absorbent cotton 9 is provided at the tip of the brush plating tool 7, and a chemical supply tube 10 is disposed in the through-hole 8 to supply chemical solution (plating solution) 11 to the absorbent cotton 9. The chemical supply tube 10 is connected to a feed pump 13 disposed on a base 12. The feed pump 13 is connected via a tube to the chemical solution in a chemical solution tank 14 disposed on the base 12, and by operating the feed pump 13, the chemical solution is supplied from the chemical supply tube 10 into the through-hole 8 in which the brush plating tool 7 is disposed.

[0014] The brush plating tool 7 is connected to a power source 15. A sensor 16 is provided on the handle 6 of the common jig body 3. Rotating the handle 6 in the circumferential direction causes the sensor 16 to react, allowing electricity to flow from the power source 15 to the brush plating tool 7. When electricity flows through the brush plating tool 7, the supply pump 13 starts operating. When the supply pump 13 starts operating, chemical solution (plating solution) 11 is supplied to the tip of the brush plating tool 7 via the chemical solution supply tube 10, so that plating is performed only on the area touched by the tip of the brush plating tool 7. Because the tip of the brush plating tool 7 is covered with absorbent cotton 9, the chemical solution 11 is supplied to the tip of the brush plating tool 7. Because the common jig body 3 has a shape that faces the shape of the seat surface of the valve seat 4, the chemical solution 11 remains inside the through hole 8 where the brush plating tool 7 is located, and plating occurs at the tip of the brush plating tool 7.

[0015] A chemical solution receptacle 17 is provided below the common jig body 3. Of the chemical solution 11 remaining inside the through-hole 8, the chemical solution that has not been used for plating with the brush plating tool 7 flows down through the gap between the common jig body 3 and the valve seat 4 into the inside of the valve seat 4 and accumulates inside the chemical solution receptacle 17. The chemical solution receptacle 17 is configured to receive the chemical solution 11 that has flowed down. A suction tube 19 connected to a suction pump 18 is inserted into the chemical solution receptacle 17. The chemical solution 11 contained in the chemical solution receptacle 17 is sucked up by the suction pump 18 via the suction tube 19 and collected in the chemical solution tank 14. The chemical solution 11 collected in the chemical solution tank 14 is reused for plating processing with the brush plating tool 7.

[0016] The common jig 1 shown in Figure 1 for repairing welds and lapping contact surfaces is used as follows. The method of using the common jig 1 will be described based on the process diagram in Figure 3. As shown in step 1 (S100) of Figure 3, a weld repair process is carried out. In the weld repair process S100, a brush plating tool 7 is attached to the common jig body 3 of the common jig 1 (S101). Next, the common jig body 3 is placed on the valve seat 4 (S102). Using the brush plating tool 7 attached to the common jig body 3, plating is performed on the repair area on the seat surface of the valve seat 4 (S103).

[0017] The plating process for the repaired portion of the seat surface is performed as follows. The handle 6 is rotated circumferentially to rotate the common jig body 3. The rotation of the handle 6 triggers a sensor 16, which then supplies electricity from the power source 15 to the brush plating tool 7. At the same time, the feed pump 12 operates, supplying the chemical (plating solution) 11 to the tip of the brush plating tool 7. This plating process is performed for the repaired portion of the seat surface of the valve seat 4. When using a Co-based alloy such as Stellite™, which has a composition of Co-30% Cr by mass, for the valve seat 4, it is preferable to use Ni plating, which is compatible with Co-based alloys. This Ni-plating repair method reduces deformation and residual stress and eliminates the need for heat treatment, potentially reducing work time. Furthermore, the use of electrolytic brush plating technology allows for easy, localized repairs without the need to transport the equipment from the power plant to the manufacturing plant.

[0018] Next, as shown in step 2 (S200) of Figure 3, a lapping process of the welded portion (seat portion) is carried out. In the lapping process S200 of the welded portion, paper is fixed between the common jig body 3 of the common jig 1 and the valve seat 4 (S201). The common jig body 3 is rotated with the handle 6 to perform lapping on the seat surface of the valve seat 4. This finishes the plating layer and uniformly finishes the seat surface (contact surface) of the valve seat 4 at the same time. In this way, the repaired portion of the seat surface of the valve seat 4 can be repaired by plating, and finishing of the plated surface and lapping of the seat surface (contact surface) can be performed.

[0019] For example, during periodic inspections of power plants, steam valves are opened and inspected, and a seat contact inspection is performed to confirm that the main valve and valve seat are in uniform contact with each other over the entire circumferential direction. If uniform contact cannot be ensured at the seat, a valve seat lapping operation involves preparing a lapping tool with a shape that matches the seat shape of the valve seat, and then lapping the seat by rotating the lapping tool in the circumferential direction with paper or the like sandwiched between the lapping tool and the seat. The common jig 1 for repairing welds and lapping contact surfaces of the embodiment is equipped with a brush plating mechanism on the lapping tool with a shape that matches the seat shape, allowing for lapping of the seat surface and maintenance of the plating coating at the same time, significantly reducing work time.

[0020] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0021] 1...Common jig for repairing welds and grinding contact surfaces, 3...Common jig body, 4...Valve seat, 6...Handle, 7...Plating brush (brush plating tool), 11...Chemical solution, 13...Feed pump, 14...Chemical solution tank, 15...Power supply, 16...Sensor, 17...Chemical solution receiver, 18...Suction pump.

Claims

1. a jig body having a rotationally symmetric shape about a central axis and a portion formed in a circumferential direction that can be brought into close contact with a welded portion that is to be fitted to a seat surface of a valve seat or a main valve; a plating mechanism having a plating brush attached to the jig body and a chemical supply line connected to the brush, and forming a plating layer on a plating target part while the valve seat or the main valve is in an installed state without disassembling the valve seat or the main valve; A common jig for repairing welded parts and lapping contact surfaces.

2. 2. The common jig for repairing welded parts and rubbing contact surfaces according to claim 1, which is configured to enable simultaneous finishing of the plating layer applied to the welded parts and rubbing for adjusting the contact of the sheet parts.

3. the valve seat or the seat surface of the main valve is made of a Co-based alloy; 2. The common jig for repairing welded portions and lapping contact surfaces according to claim 1, wherein the portion to be plated is repaired by Ni plating using the writing tool for electrolytic plating.

4. 2. The common jig for repairing welded portions and lapping contact surfaces according to claim 1, wherein the portion capable of coming into close contact with the welded portion has a shape opposite to the shape of the sheet surface.

5. 2. The common jig for repairing welded portions and lapping contact surfaces according to claim 1, further comprising a chemical solution receptacle for storing the remaining plating solution used in forming the plating layer, the chemical solution receptacle being provided below the attachment position of the brush.

6. 6. A common jig for repairing welded parts and lapping contact surfaces according to claim 5, which is configured so that continuous plating processing can be performed by automatically feeding and recovering the plating liquid.

7. A method for using the common jig for repairing welded parts and lapping contact surfaces according to claim 1, a step of repairing the valve seat or the seat surface of the main valve by plating using the plating brush; a step of finishing the plating repair portion of the sheet surface and lapping the sheet surface using the jig body; A method for using a common jig for repairing welded parts and lapping contact surfaces.

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