Repair method

Abstract

To suppress welding heat input to a repair target during repair, thereby suppressing deformation around a portion to be repaired and dilution of a base material into a welding material.SOLUTION: The present disclosure relates to a repair method for repairing a portion to be repaired located on a base material that constitutes a repair target, the method forming a corrosion-resistant layer on the portion to be repaired by using a high corrosion-resistant material containing at least one of high-nitrogen stainless steel and a Ni-based alloy as a welding material and employing a directed energy deposition method.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to repair methods. [Background technology]

[0002] For example, in seawater pumps that handle seawater, coatings are sometimes applied to the substrate surface to improve the corrosion resistance and durability of components that mainly contain metallic materials. Coatings are applied to the substrate surface by techniques such as painting, thermal spraying, PVD (Physical Vapor Deposition), and CVD (Chemical Vapor Deposition). For example, Patent Document 1 proposes a configuration that can prevent corrosion by forming a coating on the substrate surface of a shaft sleeve that is fixed to the outer peripheral surface of a rotating shaft in a seawater pump, the surface facing the rotating shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-105340 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned configuration in which a coating is formed on the surface of a substrate, there is a risk that crevice corrosion will progress from the boundary between the coating and the substrate to the substrate. Therefore, it is necessary to carry out a repair process in which a corrosion-resistant layer is formed by overlay welding at the defective or damaged areas of the coating.

[0005] In repair processes involving such welding work, if the welding heat input generated when repairing the object to be repaired is large, deformation around the repaired part of the object to be repaired and dilution of the base metal in the welding material may become significant, and the properties of the welding material may not be obtained.

[0006] At least one embodiment of the present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a repair method that can suppress deformation around the repaired portion of the object to be repaired and dilution of the base metal in the welding material by suppressing welding heat input to the object to be repaired during repair. [Means for solving the problem]

[0007] In order to solve the above problem, a repair method according to at least one embodiment of the present disclosure includes: A repair method for repairing a portion to be repaired on a base material constituting an object to be repaired, comprising: A highly corrosion-resistant material containing at least one of high-nitrogen stainless steel and Ni-based alloy is used as a welding material, and a corrosion-resistant layer is formed on the part to be repaired by using a directed energy deposition method. [Effects of the Invention]

[0008] According to at least one embodiment of the present disclosure, a repair method can be provided that can suppress deformation around the repaired portion and dilution of the base metal in the welding material by suppressing welding heat input to the object to be repaired during repair. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a pump device according to an embodiment; [Figure 2] FIG. 2 is a partial enlarged view of region A in FIG. [Figure 3] 1 is a flowchart illustrating a repair method according to one embodiment. [Figure 4] 4 is a schematic diagram showing how the repaired portion is welded by the repair method of FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the configurations described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0011] First, a description will be given of an object to be repaired by a repair method according to at least one embodiment of the present disclosure. In the following description, a pump device will be shown as an example of an object to be repaired. Fig. 1 is a schematic diagram of a pump device 1 according to one embodiment.

[0012] The pump device 1 is a pump device for pumping up and pressure-feeding a fluid, such as seawater or river water, from a water intake tank 2. The pump device 1 has a suction port 4 for taking in the fluid from the water intake tank 2. The lower side of the suction port 4 is open to the water intake tank 2, making it possible to take in the fluid stored in the water intake tank 2. The upper side of the suction port 4 is connected to the lower end of a water lift pipe 8 via a discharge bowl 6. The water lift pipe 8 is supported by a frame 2a that constitutes the water intake tank 2 via a support member 10. The upper end of the water lift pipe 8 is connected to an elbow pipe 12 for discharging the fluid pumped up by the pump device 1 to a supply destination (not shown).

[0013] The pump device 1 has a rotating shaft 14. The rotating shaft 14 extends substantially vertically through the elbow pipe 12, the lifting pipe 8, and the discharge bowl 6, and one end of the rotating shaft 14 is connected to a drive source 16, such as an electric motor. When the rotating shaft 14 is driven by the drive source 16, an impeller 18 provided on the other end of the rotating shaft 14 can rotate. The impeller 18 is housed in the discharge bowl 6 and is located below the draft of the fluid stored in the intake tank 2. The configuration of the impeller 18 will be described later with reference to FIG.

[0014] The rotating shaft 14 is rotatably supported by an outer bearing 20 and submerged bearings 22, 24. The outer bearing 20 is a rolling bearing such as a ball bearing, or a plain bearing, and is arranged on the rotating shaft 14 above the elbow pipe 12. The submerged bearings 22, 24 are plain bearings. The submerged bearing 22 is housed in the discharge bowl 6 and is arranged above the impeller 18. The submerged bearing 24 is arranged inside the riser pipe 8 and is supported on the inner surface of the riser pipe 8 by a support member 26.

[0015] In the pump device 1 having such a configuration, when the impeller 18 is rotated via the rotating shaft 14 by the driving source 16, the fluid stored in the water intake tank 2 is sucked in through the suction port 4, passes through the discharge bowl 6, the lifting pipe 8, and the elbow pipe 12 in that order, and is pumped to the supply destination (not shown).

[0016] 2 is a partially enlarged view of region A in FIG. 1. The impeller 18 includes a main body 30 and at least one runner vane 32 provided on the main body 30. The main body 30 is a casing that supports a root portion 32a of the runner vane 32 and is rotatable integrally with the runner vane 32 by the rotary shaft 14. The main body 30 is formed of a plate member having a predetermined thickness and has an internal space 34 therein. As will be described later, the internal space 34 is isolated from the fluid on the outside (the runner vane 32 side) and is in an oil environment by being filled with, for example, lubricating oil.

[0017] The runner vane 32 is erected on the outer surface of the main body 30 and rotates around the rotation axis 14 together with the main body 30 to pump the fluid taken in from the suction port 4. The runner vane 32 is a thin plate member having a predetermined shape suitable for pumping the fluid.

[0018] The root portion 32a of the runner vane 32 is supported rotatably about an axis L that is approximately perpendicular to the outer surface of the main body 30. An opening 30a is partially formed in the main body 30 at a position corresponding to the runner vane 32. The opening 30a is formed in a substantially circular shape centered on the axis L. A rotation support portion 36 is provided in the internal space 34 at a position corresponding to the opening 30a, for rotatably supporting the root portion 32a from the inside. The rotation support portion 36 is driven by an actuator (not shown), thereby varying the angle of the runner vane 32 about the axis L.

[0019] Rotation support portion 36 is positioned so that its outer edge portion 36a engages with opening 30a of main body 30. In particular, rotation support portion 36 has a stepped structure in which the outer diameter gradually decreases from the side closest to runner vane 32. A seal member 38 is disposed between the two to tightly seal the outer diameter of outer edge portion 36a of rotation support portion 36 closest to runner vane 32, preventing fluid from entering internal space 34 from the outside through opening 30a.

[0020] Next, a repair method to be performed on the repair object having the above configuration will be described. Fig. 3 is a flowchart showing the repair method according to one embodiment, and Fig. 4 is a schematic diagram showing how the repaired portion is welded by the repair method of Fig. 3.

[0021] First, a portion to be repaired, which is a target for applying the repair method, is identified (Step S1). In this embodiment, the outer edge portion 36a, which is the surface facing the seal member 38 of the rotation support portion 36 of the pump device 1 having the above configuration, is identified as the portion to be repaired. Damaged areas of the identified portion to be repaired are removed by machining, and a welding groove is formed.

[0022] Next, a welding material and a welding heat source to be used in the repair method are prepared (step S2). The welding material prepared in step S2 is a highly corrosion-resistant material containing at least one of high-nitrogen stainless steel and a Ni-based alloy. Specifically, as shown in FIG. 4, a welding wire 40 containing these highly corrosion-resistant materials can be used as the welding material. In this case, a hot wire may be used, which is a method of passing an electric current through the welding wire 40 and heating the wire by resistance heating. In this case, the welding material melts more easily than when a cold wire is used as the welding wire 40, and the welding heat input to the repair object during repair can be suitably suppressed.

[0023] The welding material may be a powder material containing a highly corrosion-resistant material. In this case, the welding material melts more easily than when the welding wire 40 is used as the welding material, and the welding heat input to the repair object during repair can be more appropriately suppressed.

[0024] The welding heat source prepared in step S2 is a welding heat source capable of forming a corrosion-resistant layer on the repaired portion by a directed energy deposition method. In this embodiment, laser welding is used as the directed energy deposition method. In the embodiment illustrated in Fig. 4, a laser head 42 is prepared as the welding heat source, capable of irradiating a laser beam 44, which is a heat source with a higher energy density than an arc, which is commonly used as a welding heat source.

[0025] Next, the welding material and welding heat source prepared in step S2 are put on standby (step S3). In step S3, the welding material and welding heat source are placed on standby in a predetermined position according to the shape of the object to be repaired. In the example shown in FIG. 4, a welding wire 40, which is the welding material, and a laser head 42 are placed at predetermined positions relative to a rotation support member 36, which is the object to be repaired. Specifically, the laser head 42 is installed at an angle with respect to the axis L so as not to interfere with the rotation support member 36, which is the object to be repaired. The welding wire 40 is placed on standby so that its tip can be guided from between the rotation support member 36, which is the object to be repaired, and the laser head 42 to a position where the laser light is irradiated by the laser head 42 (the outer edge portion 36a, which is the portion to be repaired).

[0026] Next, a shielding gas is supplied to the outer edge portion 36a, which is the portion to be repaired (step S4). This effectively prevents the molten base metal or welding material from being exposed to the surrounding atmosphere (such as the atmosphere) during welding by the directed energy deposition method. In particular, when the highly corrosion-resistant material used as the welding material contained in the welding wire 40 is high-nitrogen stainless steel, nitrogen gas is preferably used as the shielding gas. In this case, nitrogen is supplied by the shielding gas when the welding material containing high-nitrogen stainless steel is melted, thereby suppressing the release of nitrogen components contained in the welding material to the outside and effectively preventing a decrease in the corrosion resistance of the formed corrosion-resistant layer.

[0027] As the high-nitrogen stainless steel contained in the welding material, super duplex stainless steel can be used.

[0028] Next, the portion to be repaired is welded (step S5), and a corrosion-resistant layer is formed (step S6). In step S5, as shown in FIG. 4, for example, a laser beam 44 is irradiated from a laser head 42 onto the outer edge 36a, thereby melting the base material of the portion to be repaired and the welding wire 40, thereby performing welding. By employing a directional energy deposition method such as laser welding, this welding can locally apply energy to the portion to be repaired, thereby suppressing an increase in the surrounding temperature.

[0029] Specifically, by locally applying energy to the outer edge 36a, it is possible to suppress the temperature rise of the rotation support portion 36 and the surrounding runner vanes 32. Therefore, by using the above-described directed energy deposition method, it is possible to suppress deformation around the repaired portion and dilution of the base metal in the welding material.

[0030] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described embodiments may be combined as appropriate.

[0031] The contents described in each of the above embodiments can be understood, for example, as follows.

[0032] (1) A repair method according to one embodiment includes: A repair method for repairing a portion to be repaired on a base material constituting an object to be repaired, comprising: A highly corrosion-resistant material containing at least one of high-nitrogen stainless steel and Ni-based alloy is used as a welding material, and a corrosion-resistant layer is formed on the part to be repaired by using a directed energy deposition method.

[0033] According to the above aspect (1), a corrosion-resistant layer is formed on a portion to be repaired on a base material by using a directed energy deposition method with a highly corrosion-resistant material as a welding material. Directed energy deposition method applies energy locally, thereby suppressing welding heat input to the object to be repaired, thereby suppressing deformation around the portion to be repaired and dilution of the base material with respect to the welding material. Furthermore, the highly corrosion-resistant material used as the welding material contains at least one of high-nitrogen stainless steel and a Ni-based alloy, thereby favorably improving the corrosion resistance of the repaired portion by forming a corrosion-resistant layer.

[0034] (2) In another embodiment, in the above embodiment (1), The object to be repaired is a component provided in a range isolated from the fluid in a pump device capable of pumping a fluid by rotating an impeller connected to a rotary shaft.

[0035] According to the above aspect (2), in a pump device capable of pumping a fluid, a corrosion-resistant layer made of a highly corrosion-resistant material can be formed on a repaired portion that occurs in an object to be repaired, which is a component located in an area isolated from the fluid, thereby making it possible to preferably carry out repairs that can improve corrosion resistance.

[0036] (3) In another embodiment, in the above embodiment (2), The impeller is a body having an interior space isolated from the fluid; a runner vane provided on the body and exposed to the fluid; a rotation support portion disposed in the internal space and supporting a shaft root portion of the runner vane so that the runner vane can rotate relative to the main body; a seal member provided in the internal space so as to surround the shaft root portion in order to isolate the internal space from the fluid; Equipped with The object to be repaired includes a surface of the rotation support portion that faces the seal member.

[0037] According to the above aspect (3), a corrosion-resistant layer is formed on the part to be repaired that occurs on the surface facing the sealing member of the rotation support part that rotatably supports the shaft base part of the runner vane of the pump device, thereby making it possible to repair the part in question in an appropriate manner.

[0038] (4) In another embodiment, in any one of the above (1) to (3), The welding material is a powder material containing the highly corrosion-resistant material.

[0039] According to the above aspect (4), by using a powder material as the welding material, the welding material melts more easily than when wire is used as the welding material, and the welding heat input to the repair object during repair can be more suitably suppressed, thereby more effectively suppressing deformation around the repaired part and dilution of the base metal in the welding material.

[0040] (5) In another embodiment, in any one of the above (1) to (3), The welding material is a hot wire including the highly corrosion-resistant material.

[0041] According to the above aspect (5), by using a hot wire as the welding material, the welding material melts more easily than when a cold wire is used as the welding material, and the welding heat input to the repair object during repair can be more suitably suppressed, thereby more effectively suppressing deformation around the repaired part and dilution of the base metal in the welding material.

[0042] (6) In another embodiment, in any one of the above (1) to (5), When the directed energy deposition method is applied to the part to be repaired, a shielding gas is supplied to the part to be repaired.

[0043] According to the above aspect (6), by supplying a shielding gas to the part to be repaired, it is possible to suitably prevent the molten base material or welding material from being exposed to the surrounding atmosphere (air, etc.) when applying the directed energy deposition method.

[0044] (7) In another embodiment, in the above embodiment (6), the highly corrosion-resistant material is the high-nitrogen stainless steel; The shielding gas is nitrogen gas.

[0045] According to the above aspect (7), nitrogen gas is supplied as a shielding gas when the welding material containing high-nitrogen stainless steel is melted, thereby suppressing the release of nitrogen components contained in the welding material to the outside, and suitably preventing a decrease in the corrosion resistance of the formed corrosion-resistant layer.

[0046] (8) In another embodiment, in any one of the above (1) to (7), The high nitrogen stainless steel is a super duplex stainless steel.

[0047] According to the above aspect (8), by using super duplex stainless steel with excellent corrosion resistance as the welding material, a corrosion-resistant layer with excellent corrosion resistance can be formed.

[0048] (9) In another embodiment, in any one of the above (1) to (8), The directed energy deposition method is a laser welding method.

[0049] According to the above aspect (9), by forming a corrosion-resistant layer using irradiation of a laser, which is a heat source having a higher energy density than the arc generally used as a welding heat source, the welding heat input to the object to be repaired can be reduced, and deformation around the repaired part and dilution of the base metal in the welding material can be more effectively suppressed.

[0050] (10) In another embodiment, in any one of the above (1) to (9), The directed energy deposition method is applied with the welding heat source tilted according to the shape of the object to be repaired.

[0051] According to the above aspect (10), by tilting the welding heat source (e.g., a laser head that is the irradiation source of the laser beam 44) used in the directed energy deposition method according to the shape of the object to be repaired, repair can be carried out suitably while avoiding structural interference of the welding heat source with the surrounding structure of the repaired part. [Explanation of symbols]

[0052] 1. Pumping equipment 2 Water intake tank 2a Frame 4 Intake port 6 Discharge Bowl 8. Riser pipe 12 Elbow pipe 14 Rotation axis 16 Power Source 18 Impeller 20 Outer bearing 22,24 Underwater bearings 30 Main Unit 30a opening 32 Runnervane 32a Base 34 Interior Space 36 Rotation support part 36a outer edge 38 Sealing material 40 welding wire 42 Laser head 44 Laser Beam L axis

Claims

1. A repair method for repairing a portion to be repaired on a base material constituting an object to be repaired, comprising: A repair method in which a highly corrosion-resistant material containing at least one of high-nitrogen stainless steel and a Ni-based alloy is used as a welding material, and a corrosion-resistant layer is formed on the part to be repaired using a directed energy deposition method.

2. 2. The repair method according to claim 1, wherein the object to be repaired is a component provided in an area isolated from the fluid in a pump device capable of pumping a fluid by rotating an impeller connected to a rotating shaft.

3. The impeller is a body having an interior space isolated from the fluid; a runner vane provided on the body and exposed to the fluid; a rotation support portion disposed in the internal space and supporting a shaft root portion of the runner vane so that the runner vane can rotate relative to the main body; a seal member provided in the internal space to surround the shaft root portion in order to isolate the internal space from the fluid; Equipped with The repair method according to claim 2 , wherein the object to be repaired includes a surface of the rotation support portion that faces the seal member.

4. The repair method according to claim 1 or 2, wherein the welding material is a powder material containing the highly corrosion-resistant material.

5. The repair method according to claim 1 or 2, wherein the welding material is a hot wire containing the highly corrosion-resistant material.

6. The repair method according to claim 1 or 2, further comprising the step of supplying a shielding gas to the portion to be repaired when the directed energy deposition method is applied to the portion to be repaired.

7. the highly corrosion-resistant material is the high-nitrogen stainless steel; The repair method of claim 6, wherein the shielding gas is nitrogen gas.

8. 3. The repair method according to claim 1 or 2, wherein the high nitrogen stainless steel is a super duplex stainless steel.

9. The repair method of claim 1 or 2, wherein the directed energy deposition method is a laser welding method.

10. The repair method according to claim 1 or 2, wherein the directed energy deposition method is applied with a welding heat source tilted in accordance with the shape of the object to be repaired.

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