Jig

Abstract

To provide a jig for surface-treating only a specific part of an object to be surface-treated.SOLUTION: A jig 1 used when performing surface treatment on an object to be surface treated, wherein the object to be surface treated has a shaft portion and a head portion provided at one end of an upper portion of the shaft portion and larger than the shaft portion, the jig has elasticity, the jig includes a cylindrical jig body, and the jig has, at an upper end of the jig body, an upper mounting portion 111 that liquid-tightly closes at least a part of a lower surface of the head portion of the object to be surface treated in a state where the jig is mounted on the object to be surface treated. The jig has a lower mounting part 112 liquid-tightly closing at least a part of the lower end side of the object to be surface-treated in a state that the jig is mounted on the object to be surface-treated at the lower end of the jig body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a jig. [Background technology]

[0002] A component having a shaft portion and a head portion that is provided at one upper end of the shaft portion and is larger than the shaft portion is used as a component (inner ring) of a rolling bearing (Patent Documents 1 and 2). Here, it has been known that in order to improve the life and initial break-in of rolling bearings, parts are subjected to manganese phosphate treatment (phosphate film treatment; chemical conversion treatment that forms an oxide film) (Patent Document 1).

[0003] Conventionally, a mesh jig has been used for manganese phosphate treatment (phosphate coating treatment; chemical treatment that forms an oxide film) of rolling bearing parts (corresponding to the surface treatment object). Here, for the inner ring, which is one component of the rolling bearing, it was necessary to blacken only the end portion without performing manganese phosphate treatment (phosphate coating treatment; a chemical treatment that forms an oxide coating) on ​​the shaft portion. However, the conventional method had the problem that the stem portion was stained.

[0004] The present applicant has also developed a new tool that performs surface treatment on rolling elements without leaving any undyed areas or scratches (Patent Document 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-96448 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-80793 [Patent Document 3] Patent No. 6531232 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above-mentioned prior art, an object of the present invention is to provide a new technique for surface treating only a specific portion of an object to be surface treated. [Means for solving the problem]

[0007] [1] The present invention, which solves the above-mentioned problems, is a jig used when performing surface treatment on an object to be surface-treated. The object to be surface-treated in the present invention is characterized by having a shaft portion and a head portion that is provided at one upper end of the shaft portion and is larger than the shaft portion. The jig of the present invention is characterized in that it has elasticity. Also, the jig of the present invention is characterized in that it includes a cylindrical jig main body. The jig of the present invention has an upper mounting portion at the upper end of the jig body that liquid-tightly seals at least a portion of the underside of the head of the surface-treated object when the jig is attached to the surface-treated object. The jig of the present invention is characterized in that it has a lower mounting portion at the lower end of the jig body that liquid-tightly seals at least a portion of the lower end side of the surface-treated object when the jig is attached to the surface-treated object. According to the invention of [1], the head and bottom end of the object to be surface treated can be sealed liquid-tight, so that the surface treatment of a specific portion can be carried out efficiently.

[0008] [2] A preferred embodiment of the present invention is the jig described in [1], characterized in that the upper mounting portion liquid-tightly seals at least a portion of the underside of the head of the surface-treated object with a head-covering step portion that covers the lower end side of the head. According to the invention of [2], the head covering step can seal the underside of the head in a liquid-tight manner, and more effectively, only the head can be surface-treated.

[0009] [3] In a preferred embodiment of the present invention, the jig has an upper flange portion provided at an upper end of the jig body, the upper flange is annular, The jig according to [1] or [2], wherein the diameter of the upper flange portion is larger than that of the head portion. [3] According to the invention, by having an upper flange, the attachment of the jig becomes stable and the accuracy of the surface treatment can be improved.

[0010] [4] In a preferred embodiment of the present invention, the jig has a lower flange portion provided on a lower end side of the jig body, The lower flange portion is a member that also serves as a base portion extending below the lower end surface of the surface-treated object when the jig is attached to the surface-treated object, which is a jig described in any of [1] to [3]. [4] According to the invention, the lower flange also serves as the base, which makes the attachment of the jig more stable and improves the efficiency of the surface treatment.

[0011] [5] The present invention also provides a method for manufacturing a surface treatment apparatus, comprising: a mounting step of mounting the jig according to any one of [1] to [4] on the object to be surface-treated; a surface treatment step of immersing the object to be surface-treated, to which the jig is attached, in a liquid agent for surface treatment; The surface treatment step is a step of surface treating the head. It is also a method for producing a surface-treated object. According to the invention described in [5], by immersing the object to be surface-treated with the jig attached in the liquid agent, it is possible to efficiently treat the surface of only specific areas.

[0012] [6] The present invention also provides a method for manufacturing a rolling bearing, characterized by using an object manufactured by the method for manufacturing a surface-treated object according to [5]. According to the invention of [6], by using a surface-treated object, durability and performance can be improved in the manufacture of rolling bearings.

[0013] [7] The present invention also provides a method for manufacturing a bearing unit for a railway vehicle, characterized by using an object manufactured by the method for manufacturing a surface-treated object described in [5]. According to the invention of [7], by using a surface-treated object, durability and performance can be improved in the manufacture of bearing units for railway vehicles. [Effects of the Invention]

[0014] According to the present invention, a novel jig can be provided. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of a jig 1 according to the present embodiment. [Figure 2] 1A and 1B are a plan view and a bottom view, respectively, of a jig 1 of the present embodiment. [Figure 3] 1A and 1B are a front view (right side view, left side view, rear view) and a cross-sectional view taken along line AA of a jig 1 of the present embodiment, respectively. [Figure 4] 1 is a diagram showing a state in which the jig 1 of this embodiment is attached to an object 2 to be surface-treated. [Figure 5] 1 is a diagram showing a flow of a surface coating formation operation using the jig 1 of the present embodiment. [Figure 6] FIG. 1 is a reference schematic diagram showing a state in which an object to be surface-treated 2 having a jig 1 attached thereto is immersed in a liquid tank. [Figure 7] 1 is a diagram showing a bearing unit for a railway vehicle that uses a cylindrical body manufactured using the jig 1 of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] <1> Jig 1 The jig 1 will be described below, but it goes without saying that the technical scope of the present invention is not limited to the embodiments.

[0017] The jig 1 of this embodiment is a jig 1 used when performing surface treatment on an object 2 to be surface-treated. Here, the object to be surface-treated 2 in this embodiment has a shaft portion 21 and a head portion 22 that is provided at one end of the upper portion of the shaft portion 21 and is larger than the shaft portion 21.

[0018] The jig 1 of this embodiment is elastic and is characterized in that the jig 1 includes a cylindrical jig body 11. The jig 1 of this embodiment has an upper mounting portion 111 at the upper end of the jig body 11, which liquid-tightly seals at least a portion of the underside of the head 22 of the surface-treated object 2 when the jig 1 is attached to the surface-treated object 2. The jig 1 of this embodiment is characterized by having a lower mounting portion 112 at the lower end of the jig main body 11 that liquid-tightly seals at least a portion of the lower end side of the surface-treated object 2 when the jig 1 is attached to the surface-treated object 2.

[0019] First, the object to be surface treated 2 will be described in more detail below.

[0020] (1) Surface treatment object 2 The "object to be surface-treated 2" of this embodiment has a shaft portion 21 and a head portion 22 that is provided at one end of the upper portion of the shaft portion 21 and is larger than the shaft portion 21. Furthermore, the "object 2 to be surface treated" in this specification is not particularly limited in shape as long as it can be fitted with the jig 1 and can be surface treated.

[0021] In this embodiment, the shaft 21 is a cylindrical body having an opening 23 . However, in the present invention, there are no particular limitations on the shape of the shaft portion 21.

[0022] Furthermore, there is no particular limitation on the material of the object 2 to be surface-treated, and examples of the object 2 to be surface-treated include metal, wood, and rubber. Here, preferred examples of the metal include steel and iron.

[0023] In this embodiment, the stem 21 and head 22 of the object 2 to be surface-treated are integrally molded. However, in the present invention, the stem 21 and head 22 of the object 2 to be surface-treated may be detachable.

[0024] Furthermore, the use of the object to be surface treated 2 is not particularly limited, and a preferred example is the object to be surface treated 2 for a rolling bearing (inner ring of a rolling bearing; part for a bearing unit for a railway vehicle).

[0025] Furthermore, there is no particular limitation on the size of the object 2 to be surface treated, as long as the jig 1 can be attached to it.

[0026] Next, the jig 1 will be described in more detail.

[0027] (2) Jig 1 In this specification, the jig 1 is attached to the above-mentioned object to be surface-treated to prevent surface treatment of a specific portion.

[0028] The jig 1 of this embodiment includes a cylindrical jig body 11 having a hole 13 . In this specification, the jig body 11 is a member that seals the shaft portion 21 of the object 2 to be surface-treated in a liquid-tight manner.

[0029] Moreover, the jig body 11 of this embodiment has elasticity.

[0030] The jig body 11 is preferably made of a rubber material.

[0031] Furthermore, it is preferable that the jig body 11 has at least one of the following properties: weather resistance, ozone resistance, chemical resistance, and heat resistance, preferably one or more, more preferably two or more, more preferably three or more, and even more preferably all of them.

[0032] Here, the jig body 11 is preferably made of a hard elastic material. A preferred example of the hard elastic material is ethylene propylene rubber (EPDM).

[0033] The hardness of the jig body 11 made of an elastic material is preferably 55 degrees or more, preferably 60 degrees or more, and more preferably 65 degrees or more. Here, the hardness of the elastic material can be a value measured using a known hardness meter. Furthermore, the hardness values ​​of the elastic materials mentioned above are values ​​that do not include hardness tolerances, and products that fall within the range of hardness tolerances are also included in the lower limit values ​​of the hardness mentioned above.

[0034] The hardness of the jig body 11 made of an elastic material is preferably 75 degrees or less, and more preferably 70 degrees or less.

[0035] In the present invention, it is preferable that the entire jig 1 is made of an elastic material.

[0036] The jig 1 of this embodiment has an upper mounting portion 111 at the upper end of the jig body 11, which liquid-tightly seals at least a portion of the underside of the head 22 of the surface-treated object 2 when the jig 1 is attached to the surface-treated object 2.

[0037] Here, the upper mounting portion 111 liquid-tightly seals at least a part of the lower surface of the head portion 22 of the object 2 to be surface-treated by means of a head portion 22 covering step portion that covers the lower end side of the head portion 22 .

[0038] The jig 1 of this embodiment has an upper flange 121 provided at the upper end of the jig body 11. Here, the upper flange portion 121 is formed in an annular shape with a diameter larger than that of the head portion 22 .

[0039] In the present invention, the upper flange 121 is preferably disk-shaped. Since the upper flange 121 is formed larger than the objects 2 to be surface treated, the objects 2 to be surface treated are less likely to come into contact with each other when placed in the basket 4.

[0040] Moreover, it is preferable that the material of the upper flange portion 121 is the same as the material of the jig body 11 described above.

[0041] The jig 1 of this embodiment has a lower mounting portion 112 at the lower end of the jig body 11 that liquid-tightly seals at least a portion of the lower end side of the object 2 to be surface-treated when the jig 1 is attached to the object 2 to be surface-treated.

[0042] Here, the lower mounting part 112 liquid-tightly seals at least a part of the lower end of the shank 21 of the surface-treatment object 2 with a shank 21 covering step part that covers the lower end side of the shank 21 (shank lower ring 211). By adopting the above-described configuration, when the jig 1 is attached to the object 2 to be surface-treated, the outer surface of the shaft portion 21 can be left untreated.

[0043] The jig 1 of this embodiment has a lower flange portion 122 provided at the lower end of the jig body 11. Here, the lower flange portion 122 is formed in an annular shape with a diameter larger than that of the head portion 22 .

[0044] In the present invention, the lower flange 122 extends below the bottom surface of the object 2 to be surface treated. The lower flange 122 is inclined downward from the center of the connection with the jig body 11 toward the other end. Since the lower flange 122 has the above-described configuration, when the object to be surface treated 2 is placed on the basket 4, the bottom surface of the object to be surface treated 2 does not come into contact with the basket 4 and is therefore less likely to be damaged. That is, the lower flange 122 also serves as a base that can be placed on the ground. More specifically, it is preferable that the lower flange 122 is a member that also serves as a base that extends downward from the lower end surface of the object 2 to be surface-treated when the jig 1 is attached to the object 2 to be surface-treated.

[0045] Moreover, it is preferable that the material of the lower flange portion 122 is the same as the material of the jig body 11 described above.

[0046] (S1) Mounting process The mounting step is a step of mounting the jig 1 on a cylindrical body having a shaft portion 21 and a head portion 22 that is provided at one upper end of the shaft portion 21 and is larger than the shaft portion 21. The mounting process will be described in more detail below.

[0047] First, a cylindrical body having a shaft portion 21 and a head portion 22 that is provided at one upper end of the shaft portion 21 and is larger than the shaft portion 21 is prepared. Next, the jig 1 is placed over the cylindrical shaft portion 21 so that the jig body 11 corresponds to the shaft portion 21 of the cylindrical body. Then, the jig 1 is attached so that the step portion covering the head 22 of the jig body 11 corresponds to the head 22 of the cylindrical body. Furthermore, the jig 1 is attached to the lower end of the shaft portion 21 of the cylindrical body so that the covered step portion of the shaft portion 21 corresponds to the lower end of the shaft portion 21.

[0048] Furthermore, in a preferred embodiment of the present invention, the jig body 11 does not cover the inner surface of the object 2 to be surface-treated even after the mounting step.

[0049] (S2) Surface treatment process In this specification, the surface treatment step is a step in which the object to be surface-treated 2 is immersed in the surface treatment liquid 3 . Here, the surface treatment liquid 3 has a temperature higher than the outside air temperature. Here, the surface treatment liquid 3 is preferably a liquid having a temperature that is, for example, 10°C or more higher than the ambient temperature, preferably 20°C or more higher, preferably 30°C or more higher, preferably 40°C or more higher, preferably 60°C or more higher, preferably 80°C or more higher, or preferably 100°C or more higher.

[0050] The surface treatment liquid 3 is preferably a liquid having a temperature of, for example, 50°C or higher, preferably 60°C or higher, preferably 70°C or higher, preferably 80°C or higher, preferably 100°C or higher, or preferably 120°C or higher. Furthermore, the surface treatment liquid 3 may be, for example, a liquid having a temperature below the boiling point, preferably below 300°C, preferably below 200°C, preferably below 150°C, preferably below 100°C, or preferably below 80°C.

[0051] Here, when the object to be surface-treated 2 is immersed in the liquid tank, it is preferable that the object to be surface-treated 2 after the attachment process is placed in a basket 4 having a handle 41 and immersed in the surface treatment liquid 3 (the same applies to the subsequent processes). In the method of the present invention, the lower flange 122 extends below the bottom surface of the object to be surface-treated 2. Therefore, by placing the object to be surface-treated 2 in the basket 4 so that the lower flange 122 is at the bottom surface, the object to be surface-treated 2 is not damaged. Furthermore, since the lower flange 122 is formed larger than the objects 2 to be surface treated, when the objects 2 are placed in the basket 4, they are less likely to come into contact with each other.

[0052] In this specification, "surface treatment" includes any of chemical conversion treatment, film formation by coating with a liquid agent, and surface treatment by surface processing or modification.

[0053] Examples of chemical conversion treatments include manganese phosphate treatment (phosphate coating treatment), passivation treatment (passivation treatment), sulfurization treatment, chromate treatment, and black dyeing.

[0054] In this specification, manganese phosphate treatment (phosphate coating treatment) refers to a treatment for forming a phosphate film on a metal surface.

[0055] Manganese phosphate treatment (phosphate coating treatment) makes it possible to manufacture a surface-treated object 2 that is excellent in rust prevention and abrasion resistance. Therefore, by using manganese phosphate treatment (phosphate coating treatment) as the surface treatment, it is possible to provide a surface-treated object 2 that is excellent in rust prevention and abrasion resistance.

[0056] Examples of film formation by coating with a liquid agent include film formation using a liquid metal, dyeing, silicone film formation, and oil film formation.

[0057] Surface treatments for surface processing and modification include degreasing and polishing.

[0058] Each task will be explained in detail below. In the method for manufacturing the surface treatment object 2 of the present invention, it is not necessary to carry out all of the above steps, and steps can be selected as appropriate depending on the material and surface condition of the surface treatment object 2. In the present invention, the jig 1 may be removed as appropriate during the following operations, provided that the effects of the present invention are not impaired. In addition, the jig 1 may be removed during operations (for example, washing with water) provided that the effects of the present invention are not impaired.

[0059] (Degreasing work S21) The degreasing operation is an operation of degreasing the object 2 to be surface-treated using a degreasing agent. Here, the degreasing agent may be either an alcohol-based degreasing agent or a petroleum solvent-based degreasing agent.

[0060] Here, the degreasing operation can be performed by immersing the object 2 to be surface-treated after the mounting step in a degreasing tank filled with a degreasing agent, thereby degreasing only desired portions of the object 2 to be surface-treated.

[0061] When immersing in a degreasing tank containing a degreasing agent, the immersion time is preferably 5 minutes or more. By immersing in the degreasing tank for a time longer than the lower limit, it is possible to more reliably degrease only the desired portions of the surface treatment object 2.

[0062] When the substrate is immersed in a degreasing tank containing a degreasing agent, the immersion time is preferably 15 minutes or less.

[0063] (Water washing work S22) The water washing operation S22 is an operation of washing the surface-treated object 2 with water after the degreasing operation S21. By washing the surface-treated object 2 with water after the degreasing operation S21, the degreasing agent and oil remaining on the surface-treated object 2 can be removed. Here, a shower can be used for the washing operation.

[0064] (Phosphate coating work S23) The phosphate coating formation process is a process of manganese phosphate treating (phosphate coating treatment) the surface-treated object 2 by immersing the surface-treated object 2 after the mounting process in a manganese phosphate treatment (phosphate coating treatment) liquid (surface treatment liquid 3).

[0065] In a preferred embodiment of the present invention, the surface treatment object 2 is subjected to manganese phosphate treatment (phosphate coating treatment) by immersing the surface treatment object 2 after the mounting process in a liquid tank containing manganese phosphate treatment (phosphate coating treatment) liquid (surface treatment liquid 3).

[0066] When immersing in a liquid tank containing manganese phosphate treatment (phosphate coating treatment) liquid (surface treatment liquid 3), the immersion time is preferably 5 minutes or more. By immersing the object 2 in the solution for a time equal to or longer than the lower limit, it is possible to more reliably subject only the desired portions of the object 2 to manganese phosphate treatment (phosphate coating treatment).

[0067] When the substrate is immersed in a liquid tank containing a manganese phosphate treatment (phosphate coating treatment) liquid (surface treatment liquid 3), the immersion time is preferably 60 minutes or less. By immersing the object 2 in the solution for a time equal to or less than the upper limit, only desired portions of the object 2 can be subjected to manganese phosphate treatment (phosphate coating treatment).

[0068] The phosphate coating formation process may be carried out by heating at a temperature equal to or higher than the ambient temperature, more preferably at a temperature equal to or higher than the evaporation temperature of the liquid agent.

[0069] Here, the heating temperature of the liquid tank containing the manganese phosphate treatment (phosphate coating treatment) liquid (surface treatment liquid 3) is preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 130°C or higher. Heating above the lower limit temperature causes the water contained in the manganese phosphate treatment (phosphate coating treatment) liquid to evaporate. This evaporation of water causes convection in the liquid. By using the jig 1 of the present invention, even when convection of the liquid agent occurs, the objects to be surface-treated 2 are less likely to come into contact with each other.

[0070] The heating temperature of the liquid tank containing the manganese phosphate treatment (phosphate coating treatment) liquid (surface treatment liquid 3) is preferably 145°C or lower.

[0071] (Cooling operation S24) The cooling operation is an operation for cooling the object to be surface-treated 2 after the phosphate coating forming operation S23. Here, the cooling operation can be performed by immersing the object to be surface treated 2 after the attaching step in a water tank, thereby cooling the object to be surface treated 2.

[0072] (Cleaning work S25) The cleaning operation is an operation for cleaning the object to be surface-treated 2 after the cooling operation S24. The cleaning operation may include rinsing with water.

[0073] More preferably, the cleaning step includes cleaning with hot water. Here, the cooling operation can take the form of washing the surface-treated object 2 by immersing the surface-treated object 2 after the mounting step in a hot water bath.

[0074] (Drying work S26) The drying operation is an operation for drying the outer surface 12 of the object to be surface treated 2 after cleaning. The drying operation can be carried out using an air gun.

[0075] (Oil immersion work S27) The oiling process is a process of coating the dried surface treatment target object 2 with anti-rust oil. Here, the oil immersion work can be performed in the form of coating the surface treatment object 2 with the rust prevention oil by immersing the surface treatment object 2 in an oil tank containing the rust prevention oil.

[0076] Hereinafter, a method for manufacturing a railway vehicle bearing unit A or a rolling bearing using the object 2 that has been subjected to the above-mentioned surface treatment will be described.

[0077] Known methods can be cited as examples of methods for manufacturing a railway vehicle bearing unit A or a rolling bearing using the above-mentioned surface-treated object 2 (for example, JP 2017-129252 A). More specifically, the manufacturing method can include combining an inner ring (corresponding to the surface-treated object 2 in the present invention) having a raceway surface, an outer ring B having a raceway surface opposing the raceway surface of the inner ring, and a plurality of rollers (rolling elements C) arranged to roll freely between the raceway surface of the inner ring and the raceway surface of the outer ring B.

[0078] However, in the present invention, the specific embodiment of the manufacturing method for the railway vehicle bearing unit A using the above-mentioned surface treatment object 2 is not particularly limited, and any known manufacturing method can be adopted. [Example]

[0079] A surface-treated object 2 that had been manganese phosphate treated (phosphate coating treatment; surface treatment) was manufactured using a manufacturing method that included the steps of degreasing S21 to oil immersion S27 (see Figure 5) and varied the conditions described above.

[0080] When the manufactured surface-treated object 2 was visually inspected, no exposed metal prior to the manganese phosphate treatment (phosphate coating treatment) was found on the inner surface of the surface-treated object 2. It was also confirmed that the functional surface of the surface-treated object 2 had not been subjected to manganese phosphate treatment (phosphate coating treatment). That is, it was found that by immersing the object 2 to be surface-treated with the jig 1 of this example attached thereto, it was possible to perform manganese phosphate treatment (phosphate coating treatment; surface treatment) only on desired locations. It was also found that by adopting the above-mentioned configuration, the surface of the object 2 to be surface-treated can be coated without surface-treating the rolling surface (functional surface) of the object 2 to be surface-treated. [Industrial Applicability]

[0081] The present invention can be used for surface treatment. [Explanation of symbols]

[0082] 1 Jig 11 Jig body 111 Upper mounting part 112 Lower mounting part 121 Upper flange 122 Lower flange 13 Hole 2. Surface treatment object 21 Shaft 211 Lower shaft ring 22 Head 23 Opening 3. Surface treatment liquid 4 basket 41 Toride A. Bearing units for railway vehicles B outer ring C rolling element

Claims

1. A jig used when performing surface treatment on an object to be surface-treated, The object to be surface-treated is A shaft portion; a head portion provided at one upper end of the shaft portion and larger than the shaft portion; and The jig has elasticity, The jig is It has a cylindrical jig body, an upper attachment portion at an upper end of the jig body that liquid-tightly seals at least a portion of the lower surface of the head of the object to be surface-treated when the jig is attached to the object to be surface-treated; The jig has a lower attachment portion at the lower end of the jig body that liquid-tightly seals at least a portion of the lower end side of the object to be surface-treated when the jig is attached to the object to be surface-treated.

2. 2. The jig according to claim 1, wherein the upper mounting portion liquid-tightly seals at least a portion of the lower surface of the head of the object to be surface-treated with a head covering step that covers the lower end side of the head.

3. The jig has an upper flange provided at the upper end of the jig body, The upper flange is annular, The jig according to claim 1 or 2, wherein the diameter of the upper flange portion is larger than that of the head portion.

4. The jig has a lower flange provided on the lower end side of the jig body, The jig according to claim 1 or 2, wherein the lower flange portion is a member that also serves as a base portion extending below the lower end surface of the surface-treated object when the jig is attached to the surface-treated object.

5. a mounting step of mounting the jig according to claim 1 or 2 on the object to be surface-treated; a surface treatment step of immersing the object to be surface-treated, to which the jig is attached, in a liquid agent for surface treatment; The object to be surface treated is A shaft portion; a head portion provided at one upper end of the shaft portion and larger than the shaft portion; and The surface treatment step is a step of surface treating the head. A method for manufacturing a surface-treated object.

6. A method for manufacturing a rolling bearing, comprising using an object manufactured by the manufacturing method according to claim 5.

7. A method for manufacturing a bearing unit for a railway vehicle, comprising using an object manufactured by the manufacturing method according to claim 5.

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