Repair method for metal sheet conveyance roller and repaired metal sheet conveyance roller

Abstract

Provided is a repair method for a metal sheet conveyance roller, the repair method having: a step in which an SUS-based material is thermally sprayed onto some or all of a trunk part of a metal sheet conveyance roller to form a thermally sprayed built-up film having a film thickness of 1-6 mm; a step in which pores in the thermally sprayed built-up film are filled with a resin-based filler after forming the thermally sprayed built-up film; and a step in which a WC cermet material is thermally sprayed onto the thermally sprayed built-up film to form a WC cermet film. Also provided is a repaired metal sheet conveyance roller having, on some or all of a trunk part thereof, a thermally sprayed built-up film comprising an SUS-based material and having a film thickness of 1-6 mm, wherein a resin-based filler agent is filled into pores in the thermally sprayed built-up film, and there is a WC cermet film on the thermally sprayed built-up film.

Description

METHOD FOR REPAIRING METAL PLATE TRANSPORT ROLL AND REPAIRED METAL PLATE TRANSPORT ROLL

[0001] The present invention relates to a method for repairing a metal sheet transport roll and a repaired metal sheet transport roll. This application claims priority to Japanese Application No. 2023-219451 filed on December 26, 2023, and incorporates by reference all of the contents of said Japanese application.

[0002] Metal sheet transport rolls, such as bridle rolls, looper rolls, and steering rolls, used in metal sheet manufacturing plants gradually wear with use, resulting in a decrease in the diameter of their body parts. Metal sheet transport rolls are usually discarded when the diameter of their body parts becomes smaller than a predetermined value. On the other hand, it has been proposed to repair the body parts of metal sheet transport rolls whose diameters have been reduced so that they can be reused.

[0003] For example, Patent Document 1 proposes a method for repairing a body portion by using weld buildup. Specifically, the method proposes a method in which weld buildup is applied spirally from one end of the worn roll surface to the other end without any gaps, and after the buildup is applied to the entire surface, irregularities caused by the buildup are ground off to produce a roll having a flat, regular outer diameter.

[0004] Japanese Patent Application Publication No. 52-39553

[0005] However, since weld overlay applies a large amount of heat to the roll, when weld overlay is used to repair the body of a metal sheet transport roll, there is a risk that the heat generated during welding will accumulate in the roll, causing distortion in the roll.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a method for repairing a metal sheet transport roll that can restore the metal sheet transport roll without causing distortion by repairing it using thermal spray buildup. It also aims to provide a method for repairing a metal sheet transport roll that can improve the indentation resistance, corrosion prevention performance, and adhesion that can be problems when repairing it using thermal spray buildup. It also aims to reduce the burden on the environment by reusing used metal sheet transport rolls instead of discarding them.

[0007] (1) A method for repairing a metal sheet transport roll according to one aspect of the present invention includes the steps of: spraying a SUS-based material onto a part or all of the body of the metal sheet transport roll to form a thermal sprayed buildup coating having a thickness of 1 to 6 mm; filling pores in the thermal sprayed buildup coating with a resin-based filler after the thermal sprayed buildup coating is formed; and spraying a WC cermet material onto the thermal sprayed buildup coating to form a WC cermet coating. This repair method is for repairing a metal sheet transport roll whose body diameter has become smaller due to wear or the like.

[0008] According to this method for repairing a metal sheet transport roll, the diameter of the body can be restored to a predetermined dimension without causing distortion in the body, and the metal sheet transport roll can be restored as a roll having a thermal spray coating that is excellent in indentation resistance, corrosion prevention performance, and adhesion. Hereinafter, when simply referring to a roll in this specification, unless otherwise specified, it means a metal sheet transport roll.

[0009] (2) In the method for repairing a metal sheet transport roll of (1) above, the WC cermet material is preferably made of WC-Co, WC-CrC-Ni, or WC-Co-Cr.

[0010] (3) In the method for repairing a metal sheet transport roll according to (1) and (2) above, the thickness of the WC cermet coating is preferably 30 to 500 μm.

[0011] (4) The method for repairing a metal sheet conveying roll according to any one of (1) to (3) above preferably includes a step of filling pores in the WC cermet coating with a resin-based filler after forming the WC cermet coating.

[0012] (5) The above-described methods for repairing a metal sheet conveying roll according to (1) to (4) preferably include a step of forming a bond coat by thermal spraying before forming the thermal sprayed build-up coating.

[0013] (6) In the method for repairing a metal sheet transport roll according to (5) above, the material of the bond coat is preferably an alloy containing 40% by mass or more of Ni.

[0014] (7) In the method for repairing a metal sheet transport roll according to any one of (1) to (6) above, the diameter of the body is preferably 900 mm or more.

[0015] (8) A repaired metal plate conveying roll according to one aspect of the present invention has a thermal sprayed buildup coating made of an SUS material on a part or all of the region of the body and having a film thickness of 1 to 6 mm, the pores in the thermal sprayed buildup coating being filled with a resin-based filler, and a WC cermet coating on the thermal sprayed buildup coating.

[0016] (9) It is preferable that the diameter of the body of the repaired metal plate transport roll of (8) above is 900 mm or more.

[0017] According to the invention of the present disclosure, the roll can be restored to a predetermined diameter without causing distortion in the body portion, and can be recycled as a metal plate conveying roll having a thermal spray coating that is excellent in indentation resistance, corrosion prevention performance, and adhesion.

[0018] Fig. 1 is a front view of a metal sheet transport roll. Fig. 2 is an enlarged cross-sectional view showing the vicinity of the surface layer of the barrel in an example of a repaired metal sheet transport roll. Fig. 3 is an enlarged cross-sectional view showing the vicinity of the surface layer of the barrel in another example of a repaired metal sheet transport roll. Fig. 4 is a diagram explaining the winding angle of the repaired metal sheet transport roll.

[0019] Hereinafter, an embodiment of the present invention will be described. In the following embodiment, a metal sheet conveying roll (hereinafter, also simply referred to as a "conveying roll") used in a manufacturing plant for metal sheets such as steel sheets will be described. In a repair method according to an embodiment of the present invention, a used conveying roll whose barrel portion has become smaller in size due to wear is restored to a conveying roll having a barrel portion of predetermined dimensions and a thermal spray coating that is excellent in indentation resistance, corrosion prevention performance, and adhesion.

[0020] (Repair Target) Examples of the transport roll to be repaired include a bridle roll, a looper roll, and a steering roll.

[0021] 1 is a front view of a transport roll 10. The transport roll 10 includes a cylindrical body 11 for transporting a steel sheet and a roll shaft 12 for rotating the transport roll 10. As the transport roll 10 is used, the peripheral surface 11a of the body 11 that comes into contact with the steel sheet wears and the diameter of the body 11 decreases. When the diameter of the body 11 has decreased to a predetermined dimension, the transport roll is taken out of service and is then repaired or discarded.

[0022] A method using weld overlay is known as a method for repairing a transport roll 10 (Patent Document 1). The weld overlay method may cause distortion in the body portion. On the other hand, the repair method according to the embodiment of the present invention can repair the roll without causing distortion.

[0023] (Repair Method) A repair method according to an embodiment of the present invention will be described. The repair target is a transport roll whose barrel diameter has been reduced due to wear. The barrel of the transport roll is made of a steel material such as a high-carbon chromium bearing steel material (such as SUJ2). Although a surface layer of a different composition may remain on a portion of the circumferential surface of the barrel, the roll to be repaired usually has the steel material exposed on the circumferential surface of the barrel. Furthermore, the repair method according to an embodiment of the present invention may be performed multiple times. Therefore, in the second or subsequent repair, the thermal sprayed buildup coating sprayed in the previous repair may remain on the circumferential surface of the barrel of the roll to be repaired. Hereinafter, in the description of the embodiment of the repair method, the barrel to be repaired whose diameter has been reduced is also referred to as the repaired barrel.

[0024] <First embodiment of repair method> Fig. 2 is a partially enlarged cross-sectional view showing the vicinity of the surface layer (e.g., region A in Fig. 1) of the barrel portion 11 of a transport roll (repaired metal plate transport roll) that has been regenerated through a repair method according to this embodiment. Here, an embodiment will be described in which a steel barrel main body is the barrel portion to be repaired.

[0025] (1) A stainless steel material is thermally sprayed onto a barrel portion (barrel main body) 21 to be repaired, the diameter of which has been reduced due to wear, to form a thermal sprayed build-up coating 22. Examples of the thermal spraying method for forming the thermal sprayed build-up coating 22 include wire flame spraying and high-velocity flame spraying.

[0026] Examples of the SUS-based materials include SUS430, SUS420, SUS410, SUS304, SUS316, and SUS316L. Forming the thermal sprayed build-up coating 22 by thermal spraying a SUS-based material is advantageous in terms of forming a thick film, improving corrosion resistance, and preventing film peeling due to a linear expansion coefficient close to that of the substrate. SUS420 and SUS410 are preferred as the SUS-based materials.

[0027] The thickness of the thermal sprayed overlay coating 22 is 1 mm or more and 6 mm or less. By forming the thermal sprayed overlay coating 22 of such a thickness, it is possible to ensure a film thickness necessary for the dimensional restoration of the barrel portion of the roll. If the film thickness of the thermal sprayed overlay coating 22 is less than 1 mm, the dimensional restoration of the barrel portion may be insufficient. On the other hand, if the film thickness of the thermal sprayed overlay coating 22 exceeds 6 mm, there is a risk of cracks occurring in the formed coating. The film thickness of the thermal sprayed overlay coating 22 is preferably 3 mm or more and 5 mm or less.

[0028] (2) A step of filling the pores in the thermal sprayed overlay coating 22 formed in (1) above with a resin-based filler is carried out. Here, the thermal sprayed overlay coating 22 formed in (1) above, which has a thickness of 1 to 6 mm, has pores present within the coating. If pores exist within the thermal sprayed overlay coating 22, there is a concern that the barrel 11 of the transport roll may corrode or that dents may occur on the surface of the thermal sprayed overlay coating 22 when a load is applied to the thermal sprayed overlay coating 22. Therefore, by filling the pores in the thermal sprayed overlay coating 22 with an elastically deformable resin-based filler, the resin-based filler filled in the pores can absorb strain and impact when a load is applied to the thermal sprayed overlay coating 22, thereby preventing dents from occurring on the surface of the thermal sprayed overlay coating 22. In other words, the indentation resistance of the thermal sprayed overlay coating 22 is improved. Furthermore, corrosion of the barrel 11 of the transport roll can be prevented. Furthermore, the adhesion between the thermal sprayed buildup coating 22 and the portions adjacent to the thermal sprayed buildup coating 22 (the body portion to be repaired 21 and the bond coat 24 described below) is improved.

[0029] Examples of the resin-based filler include epoxy resin, silicone resin, polyester resin, and acrylic resin. Methods for filling the resin-based filler include, for example, brush coating, air spray gun, airless gun, and immersion. At this time, adjusting the temperature and viscosity of the resin-based filler makes it easier to fill the pores in the thermal sprayed buildup coating 22 with the resin-based filler. By such a method, the thermal sprayed buildup coating 22 is formed in which the pores are filled with the resin-based filler. The thermal sprayed buildup coating 22 may be subjected to a finishing process such as polishing depending on the application.

[0030] (3) A WC cermet material is sprayed onto the thermal sprayed buildup coating 22, the pores of which are filled with a resin-based filler, to form a WC cermet coating 23. By forming the WC cermet coating 23, the indentation resistance of the outer peripheral surface of the body portion 11 of the repaired transport roll is further improved. Examples of thermal spraying methods for forming the WC cermet coating 23 include plasma spraying and high-velocity flame spraying.

[0031] The WC cermet material may be any material containing hard particles of WC and a binder metal. Preferred WC cermet materials include WC-Co, WC-CrC-Ni, and WC-Co-Cr. The use of these WC cermet materials allows for the formation of a WC cermet coating 23 with excellent indentation resistance.

[0032] The thickness of the WC cermet coating 23 is, for example, 30 μm or more and 500 μm or less. A WC cermet coating 23 with such a thickness has very good indentation resistance. On the other hand, if the thickness of the WC cermet coating 23 is less than 30 μm, the impact resistance of the WC cermet coating 23 may be insufficient, and if the thickness exceeds 500 μm, cracks may occur in the WC cermet coating 23. The thickness of the WC cermet coating 23 is more preferably 50 μm or more and 350 μm or less.

[0033] (4) A resin-based filler is filled into the pores in the WC cermet coating 23 formed in the above (3). This makes it possible to suppress corrosion occurring between the thermal sprayed build-up coating 22 and the WC cermet coating 23.

[0034] Examples of the resin-based filler include the same materials as those described above. The method for filling the resin-based filler may be the same procedure as described above. Through this process, a WC cermet coating 23 is formed in which the pores are filled with the resin-based filler. The WC cermet coating 23 may be subjected to a finishing process such as polishing depending on the application.

[0035] The repair method according to the present embodiment restores the diameter of the roll body portion 11 through these steps, and allows the roll to be remanufactured as a transport roll having a thermal spray coating 22 that is excellent in indentation resistance, corrosion prevention, and adhesion. Because the repair method uses thermal spraying for repair, the heat accumulated in the roll body portion 11 during the buildup process can be reduced compared to when the buildup coating is formed by welding. Therefore, the repair method according to the present embodiment can prevent thermal distortion from occurring in the body portion 11. Furthermore, by filling the pores in the thermal sprayed buildup coating 22, which has a thickness of 1 to 6 mm, with a resin-based filler, the indentation resistance of the thermal sprayed buildup coating 22 is improved. Furthermore, corrosion of the body portion 11 can be suppressed. Furthermore, the adhesion between the thermal sprayed buildup coating 22 and adjacent portions is improved. Furthermore, by forming a WC cermet coating 23 on the thermal sprayed buildup coating 22, the indentation resistance of the outer peripheral surface of the repaired transport roll body portion 11 is further improved.

[0036] In this embodiment, the thermal sprayed buildup coating 22 and the WC cermet coating 23 may be formed over the entire circumferential surface of the barrel portion 21 to be repaired, or may be formed only on a portion of the circumferential surface of the barrel portion 21 to be repaired. If only a portion of the barrel portion 11 is worn away and its diameter is reduced, the thermal sprayed buildup coating 22 and the WC cermet coating 23 may be formed only on the worn portion of the circumferential surface of the barrel portion 11, or the entire circumferential surface of the barrel portion 11 may be ground to match the diameter of the worn portion, and the thermal sprayed buildup coating 22 and the WC cermet coating 23 may be formed over the entire circumferential surface of the barrel portion 11. The larger the repair area, the greater the amount of thermal strain. Therefore, the greater the proportion of the repair area that is occupied by the entire circumferential surface of the barrel portion 21 to be repaired, the more pronounced the effects of the present invention. The portion of the circumferential surface of the barrel portion 21 to be repaired may be 50% or more of the entire area of ​​the circumferential surface of the barrel portion 21 to be repaired, or may be 80% or more, or 90% or more.

[0037] <Second embodiment of repair method> Figure 3 is a partially enlarged cross-sectional view showing the vicinity of the surface layer (e.g., region A in Figure 1) of the barrel portion 11' of a transport roll (repaired metal plate transport roll) that has been regenerated through the repair method according to this embodiment. The same components as those in the first embodiment (Figure 2) are given the same reference numerals. The repair method according to this embodiment differs from the first embodiment in that it includes a step of forming a bond coat 24 before forming the thermal sprayed buildup coating 22.

[0038] (1) A bond coat 24 is formed on the barrel portion 21 of the roll to be repaired by thermal spraying. This further improves the adhesion between the barrel portion 21 to be repaired and the thermal sprayed build-up coating 22, which will be described later. Examples of thermal spraying methods for forming the bond coat 24 include wire flame spraying and high-velocity flame spraying.

[0039] The thermal spray material for forming the bond coat 24 is preferably an alloy containing 40 mass % or more of Ni, because it has excellent adhesion to the steel barrel portion 21 to be repaired and the thermal sprayed buildup coating 22 made of a SUS-based material. Examples of alloys containing Ni include NiAl alloys and NiCr alloys. Examples of NiAl alloys and NiCr alloys include 95Ni5Al, 80Ni20Al, 80Ni20Cr, and 50Ni50Cr.

[0040] From the viewpoint of ensuring good adhesion, the thickness of the bond coat 24 is preferably 30 μm or more and 150 μm or less. If the thickness of the bond coat 24 is less than 30 μm, the adhesion between the steel barrel portion 21 to be repaired and the thermal sprayed buildup coating 22 described below may be insufficient. On the other hand, if the thickness of the bond coat 24 exceeds 150 μm, residual stress may increase, and the adhesion may decrease.

[0041] (2) Next, in the same manner as steps (1) to (4) of the first embodiment of the repair method, a thermal sprayed buildup coating 22 having pores filled with a resin-based filler is formed on the bond coat 24, and further, a WC cermet coating 23 having pores filled with a resin-based filler is formed on the thermal sprayed buildup coating 22.

[0042] <Other Embodiments of Repair Method> In the repair method according to the embodiment of the present invention, the step of filling the pores in the WC cermet coating 23 with a resin-based filler is not an essential step but an optional step. Therefore, in the first and second embodiments, the step of filling the pores in the WC cermet coating 23 with a resin-based filler may be omitted. However, from the viewpoint of improving corrosion prevention performance, it is preferable to perform the step of filling the pores in the WC cermet coating 23 with a resin-based filler.

[0043] (Repaired Metal Plate Transport Roll) <First Embodiment of Repaired Metal Plate Transport Roll> Next, a repaired metal plate transport roll (hereinafter also simply referred to as a "repaired transport roll") according to an embodiment of the present invention will be described. The repaired transport roll of this embodiment has the configuration shown in FIG.

[0044] The repaired transport roll according to this embodiment is provided with a thermal sprayed buildup coating 22 made of a SUS-based material and a WC cermet coating 23 on a part or the entire area of ​​the body portion. The body portion 11 of this repaired transport roll has a cylindrical steel body portion body 21, and the thermal sprayed buildup coating 22 and the WC cermet coating 23 provided on the outer circumferential surface of the body portion body 21. The body portion body 21 is a steel material whose diameter has become smaller than when it was unused due to wear or the like.

[0045] The repaired transport roll preferably has a barrel diameter of 900 mm or more, more preferably 1100 mm or more. Even if the repaired transport roll has a barrel diameter of 900 mm or more, or even 1100 mm or more, the amount of heat stored is small and distortion of the barrel body 21 is small because the repair is performed using thermal spraying. When replacing a used roll with a new one, the cost burden is large, especially when the barrel diameter is large (for example, 900 mm or more), but by repairing as described above, this burden can be significantly reduced. In addition, the film thickness of the thermal sprayed buildup coating 22 is 1 to 6 mm.

[0046] The pores in the thermal sprayed buildup coating 22 are filled with a resin-based filler. This improves the indentation resistance of the thermal sprayed buildup coating 22. It also makes it possible to suppress corrosion of the barrel portion 11. It also improves the adhesion between the barrel portion main body 21 of the roll and the thermal sprayed buildup coating 22.

[0047] Specific examples of the resin-based filler include those similar to those employed in the repair method according to the embodiment of the present invention.

[0048] The repaired transport roll has a WC cermet coating 23 provided on the thermal sprayed buildup coating 22. This further improves the indentation resistance of the repaired transport roll. The preferred material and thickness of the WC cermet coating 23 are the same as those employed in the repair method according to the embodiment of the present invention.

[0049] The pores in the WC cermet coating 23 are filled with a resin-based filler. In this case, it is possible to suppress corrosion that occurs between the thermal sprayed buildup coating 22 and the WC cermet coating. Specific examples of the resin-based filler include those similar to those employed in the repair method according to the embodiment of the present invention.

[0050] The repaired transport roll according to the embodiment of the present invention is suitable as a roll used with a winding angle of 90 degrees or more. This is because the repaired transport roll has excellent resistance to indentation, and therefore, even if the roll has a large contact surface pressure, dents are unlikely to occur on the outer peripheral surface of the roll (body portion).

[0051] Fig. 4 is a diagram illustrating the wrapping angle of a repaired transport roll. Fig. 4 shows a cross-sectional view of a repaired transport roll in a used state, taken along a plane perpendicular to the axial direction. The wrapping angle of the repaired transport roll refers to the angle θ formed by a line segment connecting the roll center O and one end P1 and a line segment connecting the roll center O and the other end P2, where P1 is one end of the roll circumferential direction and P2 is the other end of the roll in the range where the steel sheet 1 contacts the roll 10.

[0052] The repaired transport roll is, for example, a roll used in the atmosphere. Specific examples of the repaired transport roll include a bridle roll, a looper roll, and a steering roll. Specific examples of the repaired transport roll include a transport roll for transporting steel plates. Furthermore, since the repaired transport roll contains a resin-based filler, from the viewpoint of the heat resistance temperature of the resin-based filler, the repaired transport roll is preferably used in a temperature environment of, for example, 200°C or less.

[0053] <Other Embodiments of Repaired Conveying Roll> The repaired conveying roll according to the embodiment of the present invention may include a bond coat 24 between the barrel body 21 and the thermal sprayed buildup coating 22. The bond coat 24 is preferably a coating formed by thermal spraying. The preferred material and thickness of the bond coat 24 are the same as those employed in the repairing method according to the embodiment of the present invention.

[0054] The repaired transport roll according to the embodiment of the present invention includes a WC cermet coating 23. Pores in the WC cermet coating 23 of the repaired transport roll according to the embodiment of the present invention may or may not be filled with a resin-based filler.

[0055] In the method for repairing a conveying roll according to an embodiment of the present invention and the repaired conveying roll according to an embodiment of the present invention, the thicknesses of the bond coat 24, the thermal sprayed buildup coating 22, and the WC cermet coating 23 are measured using a micrometer after application of each coating.

[0056] (Evaluation Tests) Evaluation tests conducted to evaluate the embodiments of the present invention and the results thereof are shown below. Performance was evaluated by carrying out a push-in test, an adhesion test, and a corrosion test.

[0057] (Examples 1 to 3 and Comparative Examples 1 to 4) Test specimens used in the indentation test and corrosion test were prepared by forming a thermal sprayed buildup coating and a WC cermet coating on a steel plate (made of SUJ2) measuring 50 mm in length, 50 mm in width, and 10 mm in thickness using the method described below. Test specimens used in the adhesion test were prepared by forming a thermal sprayed buildup coating and a WC cermet coating on the end face of a round bar (made of SS400) measuring 25 mm in diameter and 50 mm in length using the method described below. The thickness of the thermal sprayed buildup coating was 3.5 mm, and the thickness of the WC cermet coating was as shown in Tables 1 and 2. In Examples 1 to 3 and Comparative Example 2, the pores in the thermal sprayed buildup coating were filled with epoxy resin, and in Examples 2 and 3 and Comparative Example 4, the pores in the WC cermet coating were filled with epoxy resin.

[0058] <Formation of thermal sprayed build-up coating> Thermal spraying type: Wire flame spraying Thermal spraying material: SUS420J2

[0059] <Formation of WC cermet coating> Thermal spraying type: High velocity flame spraying Thermal spraying material: WC-20CrC-7Ni

[0060] <Filling with resin-based filler> Processing method: Brush application Filler: Epoxy resin

[0061] <Indentation test> Test specimens having the thermal spray coatings (thermal spray build-up coating + WC cermet coating) shown in Table 1 were prepared, and a universal testing machine was used to indent an SUJ2 steel ball (φ5 mm, HS62-67) into the surface of the test specimen at 5 mm / s with a force of 5 kN, and the damage depth was measured. The results are shown in Table 1.

[0062]

[0063] <Adhesion Test> Test specimens having the thermal spray coatings (thermal spray buildup coating + WC cermet coating) shown in Table 2 were prepared, and the adhesion strength of the thermal spray coatings was measured using a method in accordance with JIS H8402:2004. In accordance with the method of JIS H8402, the test specimens were attached to a universal testing machine and pulled at a pulling rate of 1 mm / min to determine the tensile breaking load. The results are shown in Table 2. In all test examples, fracture occurred within the thermal spray buildup coating.

[0064] <Corrosion Test (Cas Test)> Test pieces having the thermal spray coatings (thermal spray buildup coating + WC cermet coating) shown in Table 2 were prepared, and a corrosion test (Cas test) of the thermal spray coatings (thermal spray buildup coating + WC cermet coating) was carried out in accordance with JIS H8502: 1999. A test solution (5% NaCl + 0.027% CuCl ２ A solution of copper chloride dihydrate added to copper chloride was sprayed onto the thermal spray coating of the test piece in an environment of 50°C.

[0065] Spraying of the test liquid was continued for 96 hours, after which the corrosion resistance of the thermal sprayed coating was evaluated according to the following criteria. The results are shown in Table 2. <Evaluation criteria> A: No corrosion products were observed. B: Corrosion products occupied 20% or less of the test piece surface. C: Corrosion products occupied 50% or more of the test piece surface.

[0066]

[0067] As shown in Table 1, it was revealed that filling the pores in the thermal sprayed build-up coating with a resin-based filler improved the indentation resistance. It was also revealed that forming a WC cermet coating on the thermal sprayed build-up coating further improved the indentation resistance. As shown in Table 2, it was revealed that filling the pores in the thermal sprayed build-up coating with a resin-based filler reduced corrosion and improved adhesion. It was also revealed that filling the pores in the WC cermet coating with a resin-based filler reduced corrosion.

[0068] From the above, it was found that the above thermal spray coating has sufficient indentation resistance, adhesion, and corrosion resistance. Furthermore, since thermal spray cladding has a smaller thermal effect on the base material than weld cladding, according to the embodiment of the present invention, repair can be performed without causing distortion and while ensuring sufficient indentation resistance, adhesion, and corrosion resistance.

[0069] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims.

[0070] The repair method for a repaired transport roll according to one aspect of the present invention and the repaired transport roll according to one aspect of the present invention can be used in a manufacturing plant for metal sheets such as steel sheets.

[0071] REFERENCE SIGNS LIST 1 steel plate 10 metal plate transport roll 11, 11' barrel portion 11a peripheral surface 12 roll shaft 21 barrel portion main body (barrel portion to be repaired) 22 thermal spray cladding coating 23 WC cermet coating 24 bond coat

Claims

1. A step of spraying a SUS-based material onto a part or all of the body of the metal plate conveying roll to form a sprayed build-up coating with a film thickness of 1 to 6 mm; a step of filling pores in the sprayed build-up coating with a resin-based filler after forming the sprayed build-up coating; and a step of spraying a WC cermet material onto the sprayed build-up coating to form a WC cermet coating. A method for repairing a metal plate conveying roll having these steps.

2. The method for repairing a metal plate conveying roll according to claim 1, wherein the WC cermet material is composed of WC-Co, WC-CrC-Ni, or WC-Co-Cr.

3. The method for repairing a metal plate conveying roll according to claim 1 or 2, wherein the film thickness of the WC cermet coating is 30 to 500 μm.

4. The method for repairing a metal plate conveying roll according to claim 1 or 2, having a step of filling pores in the WC cermet coating with a resin-based filler after forming the WC cermet coating.

5. The method for repairing a metal plate conveying roll according to claim 1 or 2, having a step of forming a bond coat by spraying before forming the sprayed build-up coating.

6. The method for repairing a metal plate conveying roll according to claim 5, wherein the material of the bond coat is an alloy containing 40 mass% or more of Ni.

7. The method for repairing a metal plate conveying roll according to claim 1 or 2, wherein the diameter of the body is 900 mm or more.

8. A repaired metal plate conveying roll having a sprayed build-up coating made of a SUS-based material on a part or all of the body, with a film thickness of 1 to 6 mm, wherein the pores in the sprayed build-up coating are filled with a resin-based filler, and having a WC cermet coating on the sprayed build-up coating.

9. The repaired metal plate conveying roll according to claim 8, wherein the diameter of the body is 900 mm or more.

Images