WO2019188014A1

WO2019188014A1 - Sliding bearing and spherical sliding bearing

Info

Publication number: WO2019188014A1
Application number: PCT/JP2019/008365
Authority: WO
Inventors: 孟壇
Original assignee: Ntn株式会社
Priority date: 2018-03-28
Filing date: 2019-03-04
Publication date: 2019-10-03
Also published as: JP2019173862A

Abstract

This sliding bearing (10) is made of a titanium alloy. A sliding surface of the sliding bearing (10) is provided with an oxygen diffusion layer (10e). The nitrogen concentration in the oxygen diffusion layer (10e) is 0.5 mass% or less. The oxygen concentration in the oxygen diffusion layer (10e) is 0.6 - 8.0 mass% at the sliding surface.

Description

Plain bearings and spherical plain bearings

The present invention relates to a plain bearing and a spherical plain bearing. More specifically, the present invention relates to a titanium alloy slide bearing and a spherical slide bearing.

Titanium alloy has low wear resistance due to its low hardness compared to steel. Therefore, it is difficult to apply a titanium alloy to a machine part that requires wear resistance without performing a surface treatment. Conventionally, a titanium alloy member described in International Publication No. 97/36018 (Patent Document 1) is known. The titanium alloy member described in Patent Document 1 has a surface hardened layer on the surface.

The surface hardened layer has a first hardened layer on the surface of the titanium alloy member and a second hardened layer on the inner side of the titanium alloy member with respect to the first hardened layer. In the first hardened layer, 0.6 weight percent or more and 8.0 weight percent or less of nitrogen is solid-dissolved. In the first hardened layer, oxygen of 1.0 weight percent or more and 14.0 weight percent or less is dissolved. In the second hardened layer, 0.5 wt% or more and 14.0 wt% or less of oxygen is dissolved.

International Publication No. 97/36018

As described above, in the titanium alloy member described in Patent Document 1, the hardness of the surface hardened layer is improved by dissolving nitrogen. However, by dissolving nitrogen, the hardness of the surface hardened layer increases, but the surface hardened layer becomes brittle.

The present invention has been made in view of the above-described problems of the prior art. More specifically, the present invention provides a plain bearing and a spherical plain bearing that can improve the hardness of the sliding surface while maintaining the toughness of the sliding surface.

The plain bearing according to one aspect of the present invention is made of a titanium alloy. A plain bearing according to one embodiment of the present invention includes an oxygen diffusion layer on a sliding surface. The nitrogen concentration in the oxygen diffusion layer is 0.5 mass percent or less. The oxygen concentration in the oxygen diffusion layer is 0.6 mass percent or more and 8.0 mass percent or less on the sliding surface.

The sliding bearing according to one aspect of the present invention can improve the hardness of the sliding surface while maintaining the toughness of the sliding surface.

In the above sliding bearing, the hardness of the oxygen diffusion layer may be 480 Hv or more and 1200 Hv or less on the sliding surface. In this case, the hardness on the sliding surface can be improved while maintaining the toughness on the sliding surface.

In the above sliding bearing, the titanium alloy may be a 64 titanium alloy. In this case, the hardness on the sliding surface can be improved while maintaining the toughness on the sliding surface.

The sliding bearing may be an aerospace sliding bearing.
A spherical plain bearing according to an aspect of the present invention includes an inner ring and an outer ring. The inner ring and the outer ring are made of a titanium alloy. At least one of the inner ring and the outer ring has an oxygen diffusion layer on the sliding surface. The nitrogen concentration in the oxygen diffusion layer is 0.5 mass percent or less. The oxygen concentration in the oxygen diffusion layer is 0.6 mass percent or more and 8.0 mass percent or less on the sliding surface.

In the above spherical plain bearing, the hardness of the oxygen diffusion layer may be 480 Hv or more and 1200 Hv or less on the sliding surface. In this case, the hardness on the sliding surface can be improved while maintaining the toughness on the sliding surface.

In the above spherical plain bearing, the titanium alloy may be a 64 titanium alloy. In this case, the hardness on the sliding surface can be improved while maintaining the toughness on the sliding surface.

The above spherical plain bearing may further include a self-lubricating liner disposed between the inner ring and the outer ring. In this case, friction between the inner ring and the outer ring can be reduced.

In the above spherical plain bearing, the liner may be a woven fabric including at least one fiber selected from the group consisting of polytetrafluoroethylene fiber, aramid fiber, glass fiber, and polyester fiber. In this case, the friction between the inner ring and the outer ring can be further reduced.

In the above-described spherical plain bearing, the liner may be a molded body including at least one material selected from the group consisting of polytetrafluoroethylene, polyamide, polyimide, and polyphenylene sulfide. In this case, the friction between the inner ring and the outer ring can be further reduced.

The above spherical plain bearing may be an aerospace spherical plain bearing.

The sliding bearing according to one aspect of the present invention can improve the hardness of the sliding surface while maintaining the toughness of the sliding surface. The spherical plain bearing according to one aspect of the present invention can improve the hardness of the sliding surface while maintaining the toughness of the sliding surface.

It is a top view of the machine part concerning an embodiment. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. It is an enlarged view in the area | region III of FIG. It is process drawing which shows the manufacturing method of the machine component which concerns on embodiment. It is a typical graph which shows the relationship between the hardness from the test piece 1 and the test piece 2, and the distance from the surface. 3 is a schematic graph showing the relationship between the oxygen concentration in the test piece 1 and the distance from the surface. 3 is a schematic graph showing a relationship between an oxygen concentration in a test piece 2 and a distance from a surface. It is a typical graph which shows the relationship between the oxygen concentration in the diffused layer 10e of the test piece 1 and the test piece 2, and hardness. It is sectional drawing of the spherical plain bearing 20 which concerns on embodiment. It is process drawing which shows the manufacturing method of the spherical plain bearing 20 which concerns on embodiment.

Hereinafter, embodiments will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

(Configuration of mechanical parts according to the embodiment)
Hereinafter, the configuration of the mechanical component according to the embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a top view of a mechanical component according to the embodiment. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. As shown in FIGS. 1 and 2, the mechanical component according to the embodiment is a slide bearing 10. However, the machine component according to the embodiment is not limited to this.

The slide bearing 10 is made of a titanium (Ti) alloy. The titanium alloy constituting the slide bearing 10 is ASTM standard B348-13GR. The Ti-6Al (aluminum) -4V (vanadium) alloy specified in 5 is preferable. Hereinafter, this Ti-6Al-4V alloy is referred to as a 64 titanium alloy.

The sliding bearing 10 is composed of a ring-shaped member. The plain bearing 10 has an upper surface 10a, a bottom surface 10b, an inner peripheral surface 10c, and an outer peripheral surface 10d. The bottom surface 10b is a surface opposite to the top surface 10a. The outer peripheral surface 10d is a surface opposite to the inner peripheral surface 10c. The top surface 10 a and the bottom surface 10 b are surfaces of the slide bearing 10 that are orthogonal to the central axis of the slide bearing 10. The inner peripheral surface 10c and the outer peripheral surface 10d are connected to the upper surface 10a and the bottom surface 10b. The distance between the inner peripheral surface 10c and the central axis is smaller than the distance between the outer peripheral surface 10d and the central axis. The inner peripheral surface 10c constitutes a sliding surface (surface on the side in contact with the shaft) of the slide bearing 10.

FIG. 3 is an enlarged view of region III in FIG. As shown in FIG. 3, the plain bearing 10 has a diffusion layer 10e (oxygen diffusion layer). The diffusion layer 10e is provided on the inner peripheral surface 10c. The diffusion layer 10e has a depth D. The depth D is a distance from the inner peripheral surface 10c in a direction orthogonal to the inner peripheral surface 10c. The depth D is 0.05 mm or more. Preferably, the depth D is 0.2 mm or more. Particularly preferably, the depth D is 0.25 mm or more.

In the diffusion layer 10e, the nitrogen concentration is 0.5 mass percent or less. That is, in the diffusion layer 10e, the nitrogen concentration may be 0.5 mass percent or less, and the diffusion layer 10e may not contain nitrogen. In the diffusion layer 10e, nitrogen is dissolved in the titanium alloy.

In the diffusion layer 10e on the inner peripheral surface 10c, the oxygen concentration is 0.6 mass percent or more and 8.0 mass percent or less. The oxygen concentration in the diffusion layer 10e on the inner peripheral surface 10c is set to 8.0 mass percent or less in consideration of the hardness and toughness required for a titanium alloy bearing. In the diffusion layer 10e on the inner peripheral surface 10c, the oxygen concentration is preferably 1.0 mass percent or more and 6.0 mass percent or less. The oxygen concentration in the diffusion layer 10e decreases as the distance from the inner peripheral surface 10c increases. In the diffusion layer 10e, oxygen is dissolved in the titanium alloy.

The nitrogen concentration and oxygen concentration in the diffusion layer 10e are measured by, for example, EPMA (electron beam microanalyzer).

In the inner peripheral surface 10c, the hardness of the diffusion layer 10e is preferably 600 Hv or more and 1500 Hv or less. On the inner peripheral surface 10c, the hardness of the diffusion layer 10e may be not less than 480 Hv and not more than 1200 Hv.

The hardness of the diffusion layer 10e is measured according to the Vickers hardness test method defined in JIS Z 2244: 2009.

In the diffusion layer 10e, the titanium alloy constituting the slide bearing 10 includes crystal grains composed of an α phase. The crystal grains composed of the α phase are preferably arranged equiaxially in the diffusion layer 10e.

Hereinafter, a method for manufacturing a mechanical component according to the embodiment will be described with reference to FIG. FIG. 4 is a process diagram illustrating a method for manufacturing a mechanical component according to the embodiment. As shown in FIG. 4, the method for manufacturing a machine part according to the embodiment includes a preparation step S1, an acid immersion step S2, a cooling step S3, and a post-processing step S4.

In the preparation step S1, preparation of a workpiece is performed. This workpiece is a ring-shaped member made of a titanium alloy when the mechanical component according to the embodiment is the slide bearing 10. The processing object has an inner peripheral surface. The inner peripheral surface of the object to be processed is a surface that finally becomes the inner peripheral surface 10c of the slide bearing 10.

In the soaking step S2, soaking treatment is performed on the surface of the workpiece. More specifically, the dipping treatment is performed on the inner peripheral surface of the workpiece. In the immersion treatment, heat treatment is performed using a heat treatment furnace in an atmosphere containing oxygen. The atmospheric gas containing oxygen is, for example, an endothermic modified gas. The heating temperature in the heat treatment is preferably 900 ° C. or higher and 1000 ° C. or lower. The heating temperature in the heat treatment is particularly preferably 920 ° C. or higher and 950 ° C. or lower. The holding time in the heat treatment is preferably 5 hours or more and 20 hours or less. The holding time in the heat treatment is preferably 6 hours or more and 15 hours or less.

In the immersion step S2, oxygen in the atmosphere enters and diffuses from the surface of the workpiece to the inside of the workpiece, thereby forming the diffusion layer 10e. In the immersion step S2, a titanium oxide (TiO ₂ , TiO, etc.) film is formed on the surface of the workpiece. This titanium oxide film is removed, for example, in the post-processing step S4.

In the cooling step S3, the workpiece is taken out from the heat treatment furnace and cooled. The workpiece is cooled by holding the workpiece taken out from the heat treatment furnace in, for example, semi-hot oil.

In post-processing process S4, the post-processing with respect to a process target object is performed. In the post-processing step S4, for example, machining such as cleaning of the workpiece, grinding or polishing of the workpiece is performed. Thereby, the sliding bearing 10 is manufactured from a workpiece.

(Relationship between diffusion layer hardness and oxygen concentration in diffusion layer)
Below, the evaluation test about the relationship between the hardness of the diffusion layer 10e and the oxygen concentration in the diffusion layer 10e and the result are demonstrated.

<Specimen>
First, the test piece used for said test is demonstrated. Table 1 shows the composition of the titanium alloy used for each test piece. As shown in Table 1, the titanium alloy used for each test piece is a 64 titanium alloy. Moreover, the oxygen concentration in the titanium alloy used for the test piece is 0.2 mass percent or less, and the nitrogen concentration in the titanium alloy used for the test piece is 0.05 mass percent or less.

<Heat treatment conditions>
The test piece was subjected to the immersion step S2 and the cooling step S3. Table 2 shows the heating temperature, holding time, and atmospheric gas in the soaking step S2. As shown in Table 2, in the test piece 1, the heating temperature was 950 ° C., and the holding time was 6.75 hours. In test piece 2, the heating time was 920 ° C. and the holding time was 14.4 hours. In both the test piece 1 and the test piece 2, the heat treatment was performed in an endothermic modified gas. Moreover, cooling process S3 was performed by hold | maintaining in a 100 degreeC semi-hot oil.

<Hardness evaluation test>
FIG. 5 is a schematic graph showing the relationship between the hardness of the test piece 1 and the test piece 2 and the distance from the surface. As shown in FIG. 5, the hardness of the test piece 1 and the test piece 2 decreases as the distance from the surface increases. In the test piece 1 and the test piece 2, the hardness was 400 Hv or more in the region between the surface and the position where the distance from the surface was 0.25 mm. Since the thickness of the titanium oxide film (scale) formed on the surface of the test piece 1 and the test piece 2 is about 0.01 mm, the depth D is 0.2 mm in the test piece 1 and the test piece 2. About a diffusion layer 10e was formed.

In the test piece 1 and the test piece 2, the hardness was 480 Hv or more in the region between the surface and the position where the distance from the surface was 0.14 mm.

FIG. 6 is a schematic graph showing the relationship between the oxygen concentration in the test piece 1 and the distance from the surface. As shown in FIG. 6, the oxygen concentration in the test piece 1 decreases as the distance from the surface increases. In the test piece 1, the oxygen concentration was 0.2 mass percent or more in a region between the surface and a position where the distance from the surface was 0.25 mm. This result also shows that the diffusion layer 10e having a depth D of about 0.2 mm is formed in the test piece 1.

In the test piece 1, the oxygen concentration was 8.0 mass percent or less at a position where the distance from the surface was 0.01 mm. That is, in the test piece 1, the oxygen concentration was 8.0 mass percent or less on the surface after the scale was removed.

In the test piece 1, the oxygen concentration was 0.6% by mass or more in the region between the surface and the position where the distance from the surface was 0.14 mm. From another viewpoint, in the test piece 1, the oxygen concentration in the diffusion layer 10e was 0.6 mass percent or more on the surface after the scale was removed.

FIG. 7 is a schematic graph showing the relationship between the oxygen concentration in the test piece 2 and the distance from the surface. As shown in FIG. 7, the oxygen concentration in the test piece 2 decreases as the distance from the surface increases. In the test piece 2, the oxygen concentration was 0.2 mass percent or more in a region between the surface and a position where the distance from the surface was 0.25 mm. This result also shows that the diffusion layer 10e having a depth D of about 0.2 mm is formed in the test piece 2.

In the test piece 2, the oxygen concentration was 8.0 mass percent or less at a position where the distance from the surface was 0.01 mm. That is, in the test piece 2, the oxygen concentration was 8.0 mass percent or less on the surface after the scale was removed.

In the test piece 2, the oxygen concentration was 0.6 mass percent or more in a region between the surface and a position where the distance from the surface was 0.14 mm. From another viewpoint, in the test piece 2, the oxygen concentration in the diffusion layer 10e was 0.6 mass percent or more on the surface after the scale was removed.

Although not shown in FIGS. 6 and 7, the nitrogen concentration in the test piece 1 and the test piece 2 was 0.05 mass percent or less at any location.

FIG. 8 is a schematic graph showing the relationship between the oxygen concentration and the hardness in the diffusion layer 10e of the test piece 1 and the test piece 2. As shown in FIG. 8, in the test piece 1, the oxygen concentration and the hardness at each position are plotted, and when the relationship between the oxygen concentration and the hardness is linearly approximated, the oxygen concentration is expressed by X (unit: mass percent), Assuming that the hardness is Y (unit: Hv), it has been clarified that X and Y have a relationship with Y = 191.27 × X + 399.43 (hereinafter referred to as Formula 1).

When the same treatment was performed on the test piece 2, it became clear that X and Y had a relationship with Y = 283.4 × X + 312.73 (hereinafter referred to as Expression 2). That is, in the test piece 1 and the test piece 2, it was shown that hardness becomes high, so that oxygen concentration becomes high. Further, from the comparison of Formula 1 and Formula 2, even when the oxygen concentration in the diffusion layer 10e is the same, the growth of the crystal grains is suppressed when the heating temperature is low and the holding time is long, so It was revealed that the hardness was further increased.

Substituting 0.6 for X in Equation 1 and Equation 2 yields Y> 480.
From the above, in the slide bearing 10 as the mechanical component according to the embodiment, when the oxygen concentration in the diffusion layer 10e on the inner peripheral surface 10c is 0.6 mass percent or more, the hardness of the diffusion layer 10e is It was revealed that the surface 10c was 4800 Hv or higher.

Hereinafter, the effect of the machine part according to the embodiment will be described. In the mechanical component according to the embodiment, the nitrogen concentration in the diffusion layer 10e is low. Therefore, in the mechanical component according to the embodiment, the toughness of the diffusion layer 10e is not easily lowered.

In the mechanical component according to the embodiment, the oxygen concentration in the diffusion layer 10e located on the surface is 0.6 mass percent or more and 8.0 mass percent. As a result, in the mechanical component according to the embodiment, the diffusion layer 10e can obtain high hardness (specifically, 480 Hv or more on the surface). Therefore, in the machine component according to the embodiment, the hardness on the surface can be improved while maintaining the toughness on the surface.

(Configuration of spherical plain bearing according to the embodiment)
Below, the structure of the spherical plain bearing 20 which concerns on embodiment is demonstrated.

FIG. 9 is a sectional view of the spherical plain bearing 20 according to the embodiment. As shown in FIG. 9, the spherical plain bearing 20 has an inner ring 21 and an outer ring 22. The spherical plain bearing 20 may further include a liner 23.

The inner ring 21 is a ring-shaped member. The inner ring 21 has an upper surface 21a, a bottom surface 21b, an inner peripheral surface 21c, and an outer peripheral surface 21d. The top surface 21a and the bottom surface 21b are orthogonal to the central axis 21e. The bottom surface 21b is a surface opposite to the top surface 21a. The inner peripheral surface 21c and the outer peripheral surface 21d are connected to the upper surface 21a and the bottom surface 21b. The inner peripheral surface 21c is linear in a cross-sectional view (in a cross section passing through the central axis 21e). The outer peripheral surface 21d has an arc shape in cross-sectional view. The distance between the inner peripheral surface 21c and the outer peripheral surface 21d once increases from the upper surface 21a toward the bottom surface 21b, and then decreases again toward the bottom surface 21b. The outer peripheral surface 21d constitutes a sliding surface. The inner ring 21 is made of a titanium alloy. The titanium alloy constituting the inner ring 21 is, for example, a 64 titanium alloy.

The outer ring 22 is a ring-shaped member. The outer ring 22 has an upper surface 22a, a bottom surface 22b, an inner peripheral surface 22c, and an outer peripheral surface 22d. The top surface 22a and the bottom surface 22b are orthogonal to the central axis 22e. The bottom surface 22b is a surface opposite to the top surface 22a. The inner peripheral surface 22c and the outer peripheral surface 22d are connected to the upper surface 22a and the bottom surface 22b. The outer peripheral surface 22d is linear in a cross-sectional view (in a cross section passing through the central axis 22e). The inner peripheral surface 22c has an arc shape in a sectional view. The distance between the inner peripheral surface 22c and the outer peripheral surface 22d once decreases from the upper surface 22a toward the bottom surface 22b, and then increases again toward the bottom surface 22b. The inner peripheral surface 22c constitutes a sliding surface. The outer ring 22 is made of a titanium alloy. The titanium alloy constituting the outer ring 22 is, for example, a 64 titanium alloy. The outer ring 22 is disposed so that the inner peripheral surface 22c faces the outer peripheral surface 21d.

The inner ring 21 has a diffusion layer 21f. The diffusion layer 21f is on the outer peripheral surface 21d. The outer ring 22 has a diffusion layer 22f. The diffusion layer 22f is on the inner peripheral surface 22c. The inner ring 21 may not have the diffusion layer 21f, and the outer ring 22 may have the diffusion layer 22f. The outer ring 22 may not have the diffusion layer 22f, and the inner ring 21 may have the diffusion layer 21f. That is, any one of the inner ring 21 and the outer ring 22 only needs to have the diffusion layer 21f (diffusion layer 22f).

The diffusion layer 21f and the diffusion layer 22f have the same configuration as the diffusion layer 10e. More specifically, the nitrogen concentration in the diffusion layer 21f (diffusion layer 22f) is 0.5 mass percent or less. The oxygen concentration in the diffusion layer 21f (diffusion layer 22f) is 1.0 mass percent or more and 8.0 mass percent or less on the outer peripheral surface 21d (inner peripheral surface 22c). Preferably, the oxygen concentration in the diffusion layer 21f (diffusion layer 22f) is 0.6 mass percent or more and 6.0 mass percent or less on the outer peripheral surface 21d (inner peripheral surface 22c).

The hardness of the diffusion layer 21f (diffusion layer 22f) on the outer peripheral surface 21d (inner peripheral surface 22c) may be not less than 480 Hv and not more than 1500 Hv. The hardness of the diffusion layer 21f (diffusion layer 22f) on the outer peripheral surface 21d (inner peripheral surface 22c) may be 4800 Hv or more and 1200 Hv or less.

The liner 23 is disposed between the inner ring 21 and the outer ring 22. More specifically, the liner 23 is attached to the inner peripheral surface 22c. The liner 23 is made of a self-lubricating material. A self-lubricating material refers to a material having a lower coefficient of friction than the counterpart material. For the liner 23, for example, a woven fabric including at least one fiber selected from the group consisting of polytetrafluoroethylene fiber, aramid fiber, glass fiber, and polyester fiber is used. The liner 23 may be a molded body including at least one material selected from the group consisting of polytetrafluoroethylene, polyamide, polyimide, and polyphenylene sulfide. In addition, when the spherical plain bearing 20 does not have the liner 23, the oil supply hole may be provided in the inner ring 21, for example.

(Method for Manufacturing Spherical Plain Bearing According to Embodiment)
Below, the manufacturing method of the spherical plain bearing 20 which concerns on embodiment is demonstrated.

FIG. 10 is a process diagram showing a method of manufacturing the spherical plain bearing 20 according to the embodiment. As shown in FIG. 10, the method for manufacturing the spherical plain bearing 20 includes an inner ring manufacturing step S5, an outer ring manufacturing step S6, a liner mounting step S7, and an assembly step S8.

In the inner ring manufacturing step S5, the inner ring 21 is manufactured. In the outer ring manufacturing step S6, the outer ring 22 is manufactured. The inner ring manufacturing step S5 and the outer ring manufacturing step S6 are performed according to the method for manufacturing a machine part according to the above embodiment. In the liner attachment step S7, the liner 23 is attached to the inner peripheral surface 22c. When the liner 23 is composed of a woven fabric, the liner 23 is attached by sticking the woven fabric to the inner peripheral surface 22c. When the liner 23 is formed of a resin molded body, the liner 23 is attached by injection molding a resin material that forms the liner 23 on the inner peripheral surface 22c.

In the assembly step S8, the inner ring 21 and the outer ring 22 are assembled. The assembly step S8 is performed by plastic processing, for example. As one of more specific methods, in the assembly step S8, firstly, a diameter expansion step for expanding the inner diameter of the outer ring 22 is performed. Second, the inner ring 21 is inserted into the outer ring 22 having an enlarged inner diameter. Thirdly, a diameter reducing process for reducing the diameter of the outer ring 22 in a state where the inner ring 21 is inserted is performed. Thus, the manufacture of the spherical plain bearing 20 is completed.

(Effect of the spherical plain bearing according to the embodiment)
Below, the effect of the spherical plain bearing 20 which concerns on embodiment is demonstrated.

As described above, in the spherical plain bearing 20, at least one of the inner ring 21 and the outer ring 22 has the diffusion layer 21f (diffusion layer 22f) having the same configuration as the diffusion layer 10e. Therefore, according to the spherical plain bearing 20, the hardness in a sliding surface can be improved, maintaining the toughness in a sliding surface.

When the spherical plain bearing 20 has the liner 23, the liner 23 is made of a self-lubricating material, so that friction between the inner ring 21 and the outer ring 22 can be reduced. When the liner 23 is a woven fabric including at least one fiber selected from the group consisting of polytetrafluoroethylene fiber, aramid fiber, glass fiber, and polyester fiber, or made of polytetrafluoroethylene, polyamide, polyimide, polyphenylene sulfide When the molded body includes at least one material selected from the group, the friction between the inner ring 21 and the outer ring 22 can be further reduced.

Although the embodiment of the present invention has been described above, the above-described embodiment can be variously modified. Further, the scope of the present invention is not limited to the above-described embodiment. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

The above-described embodiment is advantageously applied to a titanium alloy machine part, and more specifically, is particularly advantageously applied to a titanium alloy slide bearing and a spherical slide bearing.

10 sliding bearing, 10a top surface, 10b bottom surface, 10c inner circumferential surface, 10d outer circumferential surface, 10e diffusion layer, 20 spherical sliding bearing, 21 inner ring, 21a top surface, 21b bottom surface, 21c inner circumferential surface, 21d outer circumferential surface, 21e central axis, 21f diffusion layer, 22 outer ring, 22a top surface, 22b bottom surface, 22c inner peripheral surface, 22d outer peripheral surface, 22e central axis, 22f diffusion layer, S1 preparation step, S2 soaking step, S3 cooling step, S4 post-processing step, S5 inner ring Manufacturing process, S6 outer ring manufacturing process, S7 liner installation process, S8 assembly process, D depth.

Claims

A plain bearing made of titanium alloy,
The sliding bearing comprises an oxygen diffusion layer on the sliding surface,
The nitrogen concentration in the oxygen diffusion layer is 0.5 mass percent or less,
A slide bearing in which the oxygen concentration in the oxygen diffusion layer is 0.6 mass percent or more and 8.0 mass percent or less on the sliding surface.
The sliding bearing according to claim 1, wherein the hardness of the oxygen diffusion layer is not less than 480 Hv and not more than 1200 Hv on the sliding surface.
The plain bearing according to claim 1 or 2, wherein the titanium alloy is a 64 titanium alloy.
The slide bearing according to any one of claims 1 to 3, which is an aerospace slide bearing.
Inner ring,
With an outer ring,
The inner ring and the outer ring are made of a titanium alloy,
At least one of the inner ring and the outer ring has an oxygen diffusion layer on the sliding surface,
The nitrogen concentration in the oxygen diffusion layer is 0.5 mass percent or less,
A spherical plain bearing in which the oxygen concentration in the oxygen diffusion layer is 0.6 mass percent or more and 8.0 mass percent or less on the sliding surface.
The spherical plain bearing according to claim 5, wherein the hardness of the oxygen diffusion layer is not less than 480 Hv and not more than 1200 Hv on the sliding surface.
The spherical plain bearing according to claim 5 or 6, wherein the titanium alloy is a 64 titanium alloy.
The spherical plain bearing according to any one of claims 5 to 7, further comprising a self-lubricating liner disposed between the inner ring and the outer ring.
The spherical plain bearing according to claim 8, wherein the liner is a woven fabric including at least one fiber selected from the group consisting of polytetrafluoroethylene fiber, aramid fiber, glass fiber, and polyester fiber.
The spherical plain bearing according to claim 8, wherein the liner is a molded body including at least one material selected from the group consisting of polytetrafluoroethylene, polyamide, polyimide, and polyphenylene sulfide.
The spherical plain bearing according to any one of claims 5 to 10, which is an aerospace spherical plain bearing.