Sliding mechanism

Abstract

To provide, in a sliding mechanism provided with a solid lubricant film, a technique that enhances wear resistance beyond that of conventional ones.SOLUTION: A sliding mechanism (10) has a configuration in which a first sliding body (11) and a second sliding body (12) slide in a non-rolling manner. The first sliding body has a first solid lubricant film (112) formed from molybdenum disulfide. The second sliding body has a second solid lubricant film (122) formed from molybdenum disulfide. The sliding mechanism is configured such that the first solid lubricant film and the second solid lubricant film slide against each other. The first solid lubricant film is formed to have a higher hardness than the second solid lubricant film, a hardness difference being 3.7 to 4.6 GPa. Alternatively, the first solid lubricant film is formed so that an added titanium concentration becomes higher than that of the second solid lubricant film, a difference in added titanium concentration being 11 to 20 at%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] As a solid lubricant film for preventing wear due to sliding, one using a molybdenum disulfide-based material is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-95051 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, simply forming a molybdenum disulfide-based solid lubricant film on both sliding surfaces has a limited effect on improving wear resistance. Therefore, further improvement in wear resistance is necessary to extend the life of a sliding mechanism. The present invention has been made in consideration of the circumstances exemplified above. That is, the present invention provides a technology for improving wear resistance compared to conventional techniques, for example, in a sliding mechanism having a solid lubricant film. [Means for solving the problem]

[0005] The slide mechanism (10) has a configuration in which a first slide body (11) and a second slide body (12) slide in a non-rolling manner. The first slide body has a first solid lubricant film (112) formed of molybdenum disulfide. The second slide body has a second solid lubricant film (122) formed of molybdenum disulfide. The slide mechanism is configured so that the first solid lubricant film and the second solid lubricant film slide against each other. In the sliding mechanism of claim 1, the first solid lubricating film is formed to have a higher hardness than the second solid lubricating film, and the difference in hardness between the first solid lubricating film and the second solid lubricating film is 3.7 to 4.6 GPa. In the sliding mechanism according to claim 3, the first solid lubricating film is formed so as to have a higher concentration of added titanium than the second solid lubricating film, with the difference in added titanium concentration being 11 to 20 at %.

[0006] In addition, in each section of the application documents, each element may be assigned a reference symbol in parentheses. In this case, the reference symbol merely indicates an example of the correspondence between the element and the specific configuration described in the embodiment described below. Therefore, the present invention is not limited in any way by the description of the reference symbol. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a sliding mechanism according to an embodiment of the present invention. [Figure 2] 2 is a cross-sectional view showing an outline of a hypothetical wear state of the first solid lubricant film shown in FIG. 1. FIG. [Figure 3] 3 is a graph showing the relationship between the hardness difference between the first solid lubricating film and the second solid lubricating film shown in FIG. 1 and the wear cross-sectional area shown in FIG. 2. [Figure 4] 3 is a graph showing the relationship between the difference in titanium concentration between the first solid lubricating film and the second solid lubricating film shown in FIG. 1 and the wear cross-sectional area shown in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0008] (Embodiment) Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. The following embodiments, their modifications, and the accompanying drawings are schematic or simplified for the purpose of concisely explaining the contents of the present disclosure, and are not intended to limit the contents of the present disclosure in any way. Therefore, it goes without saying that the descriptions in the drawings do not necessarily correspond to the specific device configurations actually manufactured and sold. In other words, unless expressly limited by the applicant in the prosecution history of this application, it goes without saying that the present disclosure should not be interpreted as being limited by the descriptions in the drawings and the corresponding descriptions of the configurations, functions, or operations described below.

[0009] (composition) Referring to FIG. 1 , a sliding mechanism 10 according to this embodiment includes a first sliding body 11 and a second sliding body 12, and the first sliding body 11 and the second sliding body 12 slide in a non-rolling manner. The phrase "sliding in a non-rolling manner" refers to the first sliding body 11 and the second sliding body 12 moving relative to each other with sliding friction rather than rolling friction while in contact with each other. For ease of illustration and explanation, a right-handed XYZ coordinate system is set as shown in FIG. 1 . The Z-axis direction is referred to as the "height direction," and any direction within the XY plane is referred to as the "in-plane direction." In this embodiment, the sliding mechanism 10 is configured such that the first sliding body 11 and the second sliding body 12, which are arranged in the height direction, slide relative to each other along a sliding direction SD, which is the in-plane direction. Although the sliding direction SD is illustrated as being parallel to the Y-axis in FIG. 1 , it may also have an X-axis component.

[0010] The first slide body 11 has a first base material 111 and a first solid lubricant film 112. The first base material 111 is made of bearing steel such as SUJ2, on the surface of which a base film made of titanium nitride is formed, and the first solid lubricant film 112 is formed on the base film. The first solid lubricant film 112 is made of a transition metal chalcogenide. In this embodiment, the first solid lubricant film 112 is a molybdenum disulfide film. The surface of the first solid lubricant film 112 that faces the second slide body 12 is referred to as a first surface 113.

[0011] The second slide body 12 has a second base material 121 and a second solid lubricant film 122. The second base material 121 is made of bearing steel such as SUJ2, on the surface of which a base film made of titanium nitride is formed, and the second solid lubricant film 122 is formed on the base film. The second solid lubricant film 122 is made of a transition metal chalcogenide. In this embodiment, the second solid lubricant film 122 is a molybdenum disulfide film. The surface of the second solid lubricant film 122 that faces the first slide body 11 is referred to as a second surface 123.

[0012] The slide mechanism 10 is configured such that the first solid lubricant film 112 and the second solid lubricant film 122 slide against each other. A portion where the first and second solid lubricant films slide in contact with each other is referred to as a sliding portion SA. In this embodiment, the slide mechanism 10 is configured such that the sliding portion SA is substantially immobile at the first surface 113, while being movable at the second surface 123 in response to the relative movement of the first sliding body 11 and the second sliding body 12 in the sliding direction SD. Specifically, the first sliding body 11 has a convex shape such that the curvature of the first surface 113 is larger than that of the second surface 123, at least at the sliding portion SA. Such a convex shape can be, for example, a partial spherical shape such as a hemisphere, a cone shape with a rounded tip, or a semi-cylindrical shape. On the other hand, the second surface 123 can be formed as a flat surface or a curved surface with a curvature smaller than that of the first surface 113. Specifically, the second sliding body 12 can be configured as, for example, a plate-like member having a thickness direction along the height direction.

[0013] The first solid lubricating film 112 is formed to have a higher hardness than the second solid lubricating film 122. Specifically, the first solid lubricating film 112 is formed to have a higher concentration of additive elements than the second solid lubricating film 122. In this embodiment, the sliding mechanism 10 is configured so that the difference in hardness between the first solid lubricating film 112 and the second solid lubricating film 122 is 3.7 to 4.6 GPa. Specifically, the first solid lubricating film 112 and the second solid lubricating film 122 are formed so that the difference in additive titanium concentration is 11 to 20 at %.

[0014] (effect) The wear resistance performance exhibited by the sliding mechanism 10 according to this embodiment will be described below using a specific example. Referring to FIG. 1 , the basic configuration of the specific example will be described. The first sliding body 11 is spherical, and the second sliding body 12 is flat. The first solid lubricant film 112 and the second solid lubricant film 122 are formed to the same thickness. The spherical first sliding body 11 is fixed to a support (not shown) so as not to rotate. The first sliding body 11 and the second sliding body 12 are moved relative to each other one-dimensionally along the sliding direction SD parallel to the planar second surface 123. The wear amount of the second solid lubricant film 122 at this time was evaluated using the wear cross-sectional area A shown in FIG. 2. The wear cross-sectional area A is the area of ​​the worn portion as viewed from a position on the positive side of the Z axis in FIG. 2 toward the negative side of the Z axis.

[0015] 3 and 4 show the evaluation results when the hardness, i.e., the added titanium concentration, of the first slide body 11 side, i.e., the first solid lubricant film 112 side, is kept constant, and the hardness, i.e., the added titanium concentration, of the second slide body 12 side, i.e., the second solid lubricant film 122 side, is changed. In FIGS. 3 and 4, examples 1, 2, and 3 are shown from left to right. The first solid lubricant film 112 had an added titanium concentration of 20 at % and a hardness of 6.8 GPa. The added titanium concentrations and hardnesses of examples 1, 2, and 3 were as follows: Example 1: Titanium concentration: 20 at% / hardness: 6.8 GPa Example 2: Titanium concentration: 9 at% / hardness: 3.2 GPa Example 3: Titanium concentration: 0 at% / hardness: 2.3 GPa

[0016] In the evaluation method described above, higher hardness is usually more difficult to abrade, so it is expected that the smaller the hardness difference in Figure 3, and the smaller the concentration difference in Figure 4, the smaller the wear cross-sectional area A. However, as shown in Figures 3 and 4, a range of particularly good wear resistance was observed with intermediate hardness differences, i.e., concentration differences. In other words, it was confirmed that extremely good wear resistance could be obtained by setting the concentration difference to 11 to 20 at% and the hardness difference to 3.7 to 4.6 GPa.

[0017] As described above, in the present embodiment, in the slide mechanism 10 having a configuration in which the first slide body 11 slides at a fixed location while the sliding location of the second slide body 12 moves in accordance with the relative movement, typically a configuration in which the wear time is shorter on the second slide body 12 side, the first solid lubricant film 112 on the fixed side of the first slide body 11 is made relatively hard. This makes it possible to improve the wear resistance compared to conventional configurations. In particular, in a configuration in which the second slide body 12 side, which has a relatively shorter wear time, is a replaceable part while the opposite first slide body 11 side is a non-replaceable part, improving the wear resistance of the replacement-side second slide body 12 makes it possible to reduce the replacement frequency. The hardness difference can be arbitrarily set by using the amount of titanium added as an additive element. Furthermore, by setting the hardness difference within a specific range, wear resistance is particularly improved.

[0018] (Variation) The present invention is not limited to the above-described embodiment. Therefore, the above-described embodiment can be modified as appropriate. Representative modifications will be described below. In the following description of the modifications, differences from the above-described embodiment will be mainly described. Furthermore, the same reference numerals are used for parts that are identical or equivalent to each other in the above-described embodiment and the modifications. Therefore, in the following description of the modifications, the description of the above-described embodiment can be used as appropriate for components that have the same reference numerals as the above-described embodiment, unless there is a technical contradiction or special additional explanation.

[0019] The present invention is not limited to the specific configurations or structures described in the above embodiments and examples. That is, for example, the sliding direction SD may be parallel to the X-axis in FIG. 1. Furthermore, the sliding direction SD may be a one-dimensional direction or a two-dimensional direction such as the circumferential direction. Furthermore, the sliding direction SD may be constant or may vary over time.

[0020] There are no particular limitations on the materials or surface treatment conditions of the first substrate 111 and the second substrate 121. Furthermore, the materials of the first solid lubricating film 112 and the second solid lubricating film 122 are not limited to molybdenum disulfide. That is, the first solid lubricating film 112 and the second solid lubricating film 122 may be formed of a transition metal chalcogenide other than molybdenum disulfide. Even in this case, the same effects as those of the above-described embodiment and example can be achieved by creating a predetermined hardness difference depending on the amount of added element. There are also no particular limitations on the thickness relationship or film formation method of the first solid lubricating film 112 and the second solid lubricating film 122.

[0021] It goes without saying that the elements constituting the above-described embodiments are not necessarily essential unless expressly stated as essential or clearly considered essential in principle. Furthermore, when numerical values ​​such as the number, amount, range, etc. of components are mentioned, the present invention is not limited to those specific numerical values ​​unless expressly stated as essential or clearly limited to specific numerical values ​​in principle. Similarly, when the shape, direction, positional relationship, etc. of components are mentioned, the present invention is not limited to those shapes, directions, positional relationship, etc. unless expressly stated as essential or clearly limited to specific shapes, directions, positional relationship, etc. in principle.

[0022] The modified examples are not limited to the above examples. For example, other than those exemplified above, multiple embodiments may be combined with each other as long as there is no technical contradiction. Similarly, multiple modified examples may be combined with each other as long as there is no technical contradiction. [Explanation of symbols]

[0023] 10 Sliding mechanism 11 First sliding body 111 First base material 112 First solid lubricant film 113 Front page 12 Second sliding body 121 Second base material 122 Second solid lubricant film 123 Second side SA sliding part

Claims

1. A sliding mechanism (10) in which a first sliding body (11) and a second sliding body (12) slide in a non-rolling manner, the first sliding body has a first solid lubricating film (112) formed of molybdenum disulfide, the second slide body has a second solid lubricating film (122) formed of molybdenum disulfide, the first solid lubricating film and the second solid lubricating film are configured to slide against each other, the first solid lubricating film is formed to have a higher hardness than the second solid lubricating film, the difference in hardness between the first solid lubricating film and the second solid lubricating film is 3.7 to 4.6 GPa; Sliding mechanism.

2. A sliding mechanism (10) in which a first sliding body (11) and a second sliding body (12) slide in a non-rolling manner, the first sliding body has a first solid lubricating film (112) formed of molybdenum disulfide, the second slide body has a second solid lubricating film (122) formed of molybdenum disulfide, the first solid lubricating film and the second solid lubricating film are configured to slide against each other, the first solid lubricating film has a higher titanium concentration than the second solid lubricating film; the difference in titanium concentration between the first solid lubricating film and the second solid lubricating film is 11 to 20 at %; Sliding mechanism.

3. A sliding portion (SA) where the first solid lubricating film and the second solid lubricating film slide is immobile on a first surface (113) which is the surface of the first solid lubricating film, and is movable on a second surface (123) which is the surface of the second solid lubricating film. The sliding mechanism according to claim 1 or 2.

4. the first sliding body has a convex shape in the sliding portion such that the curvature of the first surface is larger than that of the second surface; The sliding mechanism according to claim 3 .

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