Sliding member and method for driving the sliding member

Abstract

The present invention relates to a sliding member and a driving method of the sliding member. A sliding member of one embodiment comprises: a shaft member having a shaft diameter D of 0.18 m or more; a bearing member capable of slidably supporting the outer peripheral surface of the shaft member; and lubricating oil supplied to a gap between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member to form an oil film in the gap, wherein the arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member is 0.23 μm or less, and the height Rpk1 of the protruding peak of the outer peripheral surface of the shaft member is 0.19 μm or less, and when the width of the inner peripheral surface of the bearing member in the axial direction is L [m], the width-to-diameter ratio calculated by L / D is less than 1, and the parameter C calculated by #imgabs0# formula 1 representing the state of the oil film n It is greater than the reference value γ(ε1) calculated based on #imgabs1# formula 2.

Description

Technical Field

[0001] The present invention relates to a sliding member and a method for driving the sliding member. Background Art

[0002] Marine sliding components include, for example, shaft components such as crankshafts, intermediate shafts, and propeller shafts, and bearing components such as sliding bearings that support the shaft components in a slidable manner. Lubricating oil is supplied to the gap between the shaft component and the bearing component. The lubricating oil forms an oil film between the shaft component and the bearing component, thereby suppressing the friction resistance between the two components.

[0003] When the thickness of the above-mentioned oil film is sufficient compared with the surface roughness of the sliding surface (in the case of fluid lubrication), the viscosity of the oil film becomes the main cause of friction resistance, so the friction resistance is easy to be maintained low. On the other hand, when the thickness of the oil film is insufficient compared with the surface roughness of the sliding surface, in addition to the viscosity of the oil film, the solid contact between the shaft component and the bearing component will also become the main cause of friction resistance, so the friction resistance is easy to increase. In addition, when the thickness of the oil film is insufficient, seizure is easy to occur on the sliding surface. Therefore, by forming a good oil film, friction loss and seizure on the sliding surface can be effectively suppressed.

[0004] As a technology for suppressing friction loss of sliding components, for example, Patent Document 1 describes a crank lubrication system for reducing friction loss of a crankshaft. As a technology for suppressing friction loss and seizure of sliding components, Patent Document 2 describes a simple method for processing a rotating shaft having a lubricating oil retaining function.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 8-121485

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 7-116958 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, the crank lubrication system described in Patent Document 1 may not be able to sufficiently suppress seizure because the crank pin has a large surface roughness and the temperature of the lubricating oil easily rises.

[0011] When manufacturing large-scale sliding components for ships, it is difficult to achieve sufficient dimensional accuracy by machining alone. In particular, in the case of sliding components with ship crankshafts, since the crank pin is eccentric relative to the journal, the dimensional accuracy of the sliding surface after machining is easily insufficient. Therefore, in large-scale sliding components for ships, it is necessary to manually grind the sliding surface of the shaft component as a finishing process. On the other hand, the processing method described in Patent Document 2 requires roll varnish processing as a finishing process, so it may not be applicable to large-scale sliding components for ships.

[0012] The present invention has been made based on the above circumstances, and an object of the present invention is to provide a sliding member capable of suppressing friction loss and seizure between a shaft member and a bearing member.

[0013] Solutions to the problem

[0014] A sliding member of one embodiment of the present invention proposed to solve the above-mentioned problems comprises: a shaft member having a shaft diameter D of 0.18 m or more; a bearing member capable of slidably supporting the outer peripheral surface of the shaft member; and a lubricating oil supplied to a gap between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member to form an oil film in the gap, wherein the arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member is 0.23 μm or less, and the height Rpk1 of the protruding peak of the outer peripheral surface of the shaft member is 0.19 μm or less, and when the width of the inner peripheral surface of the bearing member in the axial direction is L [m], the aspect ratio calculated by L / D is less than 1, and the parameter C calculated by the following formula 1 representing the state of the oil film is n , is greater than the reference value γ(ε1) calculated based on the following formula 2.

[0015]

Formula 1

[0016]

[0017]

[0018] Wherein, in the above formula 1, α represents the contact ratio between the above-mentioned shaft component and the above-mentioned bearing component, η represents the viscosity of the above-mentioned lubricating oil [Pa·second], N represents the rotation speed of the above-mentioned shaft component [rps], W represents the maximum load applied from the outer peripheral surface of the above-mentioned shaft component to the inner peripheral surface of the above-mentioned bearing component [N], c represents the radial clearance between the above-mentioned shaft component and the above-mentioned bearing component [m], γ(ε) in the above formula 2 is the roughness parameter of the outer peripheral surface of the above-mentioned shaft component and the inner peripheral surface of the above-mentioned bearing component expressed as a function of the eccentricity ε, ε1 is the arithmetic mean roughness of the inner peripheral surface of the above-mentioned bearing component is set to Ra2 [μm], and the minimum oil film parameter value for the above-mentioned oil film to maintain the fluid lubrication state is set to Λ lim , the value calculated by the following formula 3.

[0019]

Formula 2

[0020]

[0021] Effects of the Invention

[0022] A sliding member according to one embodiment of the present invention can suppress friction loss and seizure between a shaft member and a bearing member. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic cross-sectional view showing a cross section perpendicular to the central axis of the shaft member in the sliding member according to one embodiment of the present invention.

[0024] Figure 2 This is a flowchart showing a method for driving a sliding member according to one embodiment of the present invention.

[0025] Figure 3 This is a diagram showing the relationship between the arithmetic mean roughness of the shaft member and the rotation speed of the shaft member at the time when seizure occurs.

[0026] Figure 4 This is a diagram showing the relationship between the height of the protruding peak of the shaft member and the rotation speed of the shaft member at the time when seizure occurs.

[0027] Figure 5 C is the arithmetic mean roughness of the shaft component and the time when seizure occurs. n / γ(ε1).

[0028] Figure 6 This is a diagram showing the relationship between the sandpaper number for grinding a shaft member and the arithmetic mean roughness of the shaft member.

[0029] Figure 7 This is a diagram showing the relationship between the sandpaper number for grinding a shaft member and the height of the protruding peak of the shaft member.

[0030] Figure 8 This is a graph showing the relationship between the hardness ratio of the shaft member to the bearing member and the difference in arithmetic mean roughness between the bearing member and the shaft member after a sliding test.

[0031] Fig. 9 This is a graph showing the relationship between the hardness ratio of the shaft member to the bearing member and the difference in height of the protruding peaks of the bearing member and the shaft member after the sliding test.

[0032] Explanation of symbols

[0033] 1 Shaft component

[0034] 11 Outer Surface

[0035] 2 Bearing components

[0036] 21 Inner Surface

[0037] 3 Lubricating oil

[0038] 31 Oil film

[0039] D Shaft diameter

[0040] P Center axis DETAILED DESCRIPTION

[0041] [Description of Embodiments of the Invention]

[0042] First, embodiments of the present invention will be described below.

[0043] A sliding member according to one embodiment of the present invention proposed to solve the above-mentioned problems comprises: a shaft member having a shaft diameter D of 0.18 m or more; a bearing member capable of slidably supporting the outer peripheral surface of the shaft member; and a lubricating oil supplied to a gap between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member to form an oil film in the gap, wherein the arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member is 0.23 μm or less, and the height Rpk1 of the protruding peak of the outer peripheral surface of the shaft member is 0.19 μm or less, and when the width of the inner peripheral surface of the bearing member in the axial direction is L [m], the aspect ratio calculated by L / D is less than 1, and the parameter C calculated by the following formula 1 representing the state of the oil film is n , is greater than the reference value γ(ε1) calculated based on the following formula 2.

[0044]

Formula 3

[0045]

[0046]

[0047] Wherein, in the above formula 1, α represents the contact ratio between the above-mentioned shaft component and the above-mentioned bearing component, η represents the viscosity of the above-mentioned lubricating oil [Pa·second], N represents the rotation speed of the above-mentioned shaft component [rps], W represents the maximum load applied from the outer peripheral surface of the above-mentioned shaft component to the inner peripheral surface of the above-mentioned bearing component [N], c represents the radial clearance between the above-mentioned shaft component and the above-mentioned bearing component [m], γ(ε) in the above formula 2 is the roughness parameter of the outer peripheral surface of the above-mentioned shaft component and the inner peripheral surface of the above-mentioned bearing component expressed as a function of the eccentricity ε, ε1 is the arithmetic mean roughness of the inner peripheral surface of the above-mentioned bearing component is set to Ra2 [μm], and the minimum oil film parameter value for the above-mentioned oil film to maintain the fluid lubrication state is set to Λ lim , the value calculated by the following formula 3.

[0048]

Formula 4

[0049]

[0050] The sliding component can suppress friction loss and sticking between the shaft component and the bearing component for the following reasons. Generally speaking, the oil film between the shaft component and the bearing component is used to maintain the condition of fluid lubrication state. When the above-mentioned width-to-diameter ratio is less than 1, the Dubois-Ocvirk approximation is expressed by the following formula 5. In sliding components with large-diameter shaft components, it is difficult to improve dimensional accuracy, so the contact rate between the shaft component and the bearing component is less than 1. In addition, in the design of mechanical structures, a safety factor is generally set. Therefore, in the sliding component, the above-mentioned parameter C is obtained by multiplying the left side of the following formula 5 by the contact rate α (<1) between the above-mentioned shaft component and the above-mentioned bearing component n , which is obtained by multiplying the right side of the following formula 5 by a safety factor of 3, is greater than the reference value γ(ε1), whereby the oil film is easy to maintain a fluid lubrication state. In addition, in the sliding member, since the arithmetic mean roughness Ra1 and the protruding peak height Rpk1 of the shaft member are controlled below a certain value, the reference value γ(ε1) can be reduced. Therefore, for example, even when the maximum load W is large, since the parameter C n The oil film is easy to maintain the fluid lubrication state even if the viscosity η, the rotation speed N, the width L and the shaft diameter D are controlled to be small. Therefore, the sliding member can suppress friction loss and seizure.

[0051]

Formula 5

[0052]

[0053] In addition, the friction coefficient μ between the shaft member and the bearing member under the condition that the oil film is in a fluid lubrication state is expressed by the following formula 6. Referring to the following formula 6, the friction coefficient μ is reduced by reducing the viscosity η, the rotation speed N, the width L, and the shaft diameter D. As described above, the sliding member can easily reduce the friction loss under the condition that the oil film is in a fluid lubrication state because it is easy to control the viscosity η, the rotation speed N, the width L, and the shaft diameter D to be small.

[0054]

Formula 6

[0055]

[0056] The outer circumferential surface of the shaft member and the inner circumferential surface of the bearing member have different hardnesses, and the arithmetic mean roughness of the one with higher hardness between the outer circumferential surface of the shaft member and the inner circumferential surface of the bearing member is denoted as Ra h [μm], Ra1=Ra2=Ra in the above formula 3 hWhen the outer circumference of the shaft component and the inner circumference of the bearing component continue to contact, it is easy to maintain the surface microscopic protrusions on the hardest surface of the two surfaces. In contrast, the surface of the lower hardness of the two surfaces is polished by the surface of the higher hardness of the two surfaces, so that the surface roughness is close to that of the surface. Therefore, by using the arithmetic mean roughness Ra of the outer circumference of the shaft component and the inner circumference of the bearing component, the surface roughness of the lower hardness of the two surfaces is close to that of the two surfaces. h , in the above formula 3, let Ra1=Ra2=Ra h , then the above-mentioned reference value γ(ε1) can be calculated more easily.

[0057] The contact rate α is preferably greater than 0.6. In a sliding member having a shaft member with a large diameter, it is difficult to sufficiently increase the contact rate between the shaft member and the bearing member only by machining. As a finishing process, the outer peripheral surface of the shaft member is manually ground to increase the contact rate. By increasing the contact rate α in this way, the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member are easily and uniformly contacted. As a result, the maximum load W is reduced, thereby making it easy to maintain the fluid lubrication state.

[0058] The above parameter C n , preferably lower than the value γ(ε2) calculated by the above equation 2 using the eccentricity ε2 calculated using the following equation 4. n When γ(ε2) is lower than γ(ε2), the friction loss between the shaft member and the bearing member can be sufficiently suppressed.

[0059]

Formula 7

[0060]

[0061] A driving method for a sliding member according to another embodiment of the present invention comprises a driving step of rotating the shaft member using the sliding member, wherein the sliding member comprises: a shaft member having a shaft diameter D of 0.18 m or more; a bearing member capable of slidably supporting the outer peripheral surface of the shaft member; and lubricating oil supplied to a gap between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member to form an oil film in the gap, wherein the arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member is 0.23 μm or less, and the height Rpk1 of the protruding peak of the outer peripheral surface of the shaft member is 0.19 μm or less, and when the width of the inner peripheral surface of the bearing member in the axial direction is L [m], the aspect ratio calculated by L / D is less than 1, and during stable driving of the driving step, the parameter C calculated by the above formula 1 indicating the state of the oil film is n , controlled to be above the reference value γ(ε1) calculated based on the above formula 2.

[0062] The driving method of the sliding member is to set the parameter Cn By controlling the value to be equal to or greater than the reference value γ(ε1), it is possible to suppress friction loss and seizure between the shaft member and the bearing member.

[0063] In the present invention, the term "shaft diameter" means the diameter of the outer peripheral surface of the shaft member, the term "arithmetic mean roughness" means a value measured in accordance with JIS-B0601 (2013) with a low-pass cutoff value (λc) of 2.5 mm and a high-pass cutoff value (λs) of 0.8 μm, the term "protruding peak height" means a value measured in accordance with JIS-B0671-2 (2002), the term "contact ratio of the shaft member and the bearing member" means the ratio of the portion of the total sliding area where the two members are in solid contact when the shaft member and the bearing member are slid without supplying lubricating oil, the term "radial clearance" means the value obtained by subtracting the radius of the shaft member from the radius of the bearing member, and the term "fluid lubrication state" means the state in which the shaft member is in contact with the bearing member according to the Stribeck curve. The term "eccentricity" refers to the value obtained by dividing the eccentricity between the center axis of the shaft member and the center axis of the bearing member when the shaft member is loaded by the radial clearance. The term "hardness" refers to the Vickers hardness measured in accordance with JIS-Z2244 (2009). The term "stable drive" refers to the time when the rotation of the shaft member is kept constant except when the rotation of the shaft member starts and ends.

[0064] In the present invention, the viscosity η [Pa·sec] of the lubricating oil and the density ρ [g / cm 3 ] and the kinematic viscosity ν(T)[mm 2 / sec] is calculated by the following formula 7. It is known that the density ρ of the lubricating oil depends on the temperature, but the influence is small compared with the change of the kinematic viscosity ν caused by the temperature dependence described later. Therefore, in the present invention, for the convenience of calculation, the density ρ of the lubricating oil is fixed to the value at 15°C.

[0065] η=ρν(T)×10 -3 …7

[0066] In the above formula 7, the kinematic viscosity ν(T) depends on the temperature T of the lubricating oil and is calculated by the following formula 8 using the viscosity-temperature characteristic m.

[0067]

Formula 8

[0068] v(T)=10 10(-mlogT+b) -0.7…8

[0069] In the above formula 8, the viscosity-temperature characteristic number m is calculated by the following formula 9 shown in "Method for estimating kinematic viscosity and mixing ratio" of JIS-K2283 (2000) using the known kinematic viscosity ν1 of the lubricating oil at temperature T1 [K] and the known kinematic viscosity ν2 of the lubricating oil at temperature T2 [K] (T1 < T2). In addition, as the kinematic viscosity ν1 and the kinematic viscosity ν2, the values ​​listed in the catalogue or the like can be used.

[0070] m={loglog(ν1+0.7)-loglog(ν2+0.7)} / (logT2-logT1)…9

[0071] In the above formula 8, the known kinematic viscosity ν3 of the lubricating oil at the use temperature T3 [K] is calculated by the following formula 10. As the kinematic viscosity ν3, a value listed in a catalogue or the like can be used.

[0072] b=loglog(μ3+k)+mlogT3…10

[0073] In the present invention, the so-called "oil film parameter" means the value of Λ calculated by the following formula 11 when the oil film thickness is h [μm].

[0074]

Formula 9

[0075]

[0076] [Details of Embodiments of the Invention]

[0077] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0078] [Sliding member]

[0079] Figure 1 The sliding member comprises: a shaft member 1 having a shaft diameter D of 0.18 m or more; a bearing member 2 that supports the outer peripheral surface 11 of the shaft member 1 in a slidable manner; and a lubricating oil 3. The central axis P of the shaft member 1 is in the horizontal direction ( Figure 1 The inner circumferential surface 21 of the bearing component 2 surrounds the outer circumferential surface 11 of the shaft component 1 in the circumferential direction. The lubricating oil 3 is supplied to the gap between the outer circumferential surface 11 of the shaft component 1 and the inner circumferential surface 21 of the bearing component 2. In addition, the lubricating oil 3 forms an oil film 31. In this way, the bearing component 2 has its inner circumferential surface 21 arranged relative to the outer circumferential surface 11 via the oil film 31, so that the shaft component 1 can be slidably supported. The arithmetic mean roughness Ra1 of the outer circumferential surface 11 of the shaft component 1 is less than 0.23μm, and the height Rpk1 of the protruding peak of the outer circumferential surface 11 of the shaft component 1 is less than 0.19μm. In addition, it is assumed that the inner circumferential surface 21 of the bearing component 2 is axially ( Figure 1When the width of the oil film (in the Y direction) is L [m], the aspect ratio calculated by L / D is less than 1. In addition, the parameter C calculated by the following formula 1 representing the state of the oil film is n , is greater than the reference value γ(ε1) calculated based on the following formula 2.

[0080]

Formula 10

[0081]

[0082]

[0083] In the above formula 1, α represents the contact ratio between the shaft component 1 and the bearing component 2, η represents the viscosity of the lubricating oil 3 [Pa·second], N represents the rotation speed of the shaft component 1 [rps], W represents the maximum load applied by the outer peripheral surface 11 of the shaft component 1 to the inner peripheral surface 21 of the bearing component 2 [N], c represents the radial clearance between the shaft component 1 and the bearing component 2 [m], γ(ε) in the above formula 2 is the roughness parameter of the outer peripheral surface 11 of the shaft component 1 and the inner peripheral surface 21 of the bearing component 2 expressed as a function of the eccentricity ε, ε1 is the arithmetic mean roughness of the inner peripheral surface of the bearing component 2 is Ra2 [μm], and the minimum oil film parameter value for the oil film 31 to maintain the fluid lubrication state is Λ lim When , the value calculated by the following formula 3. In addition, as the arithmetic mean roughness Ra1 of the outer peripheral surface 11 of the shaft member 1 and the arithmetic mean roughness Ra2 of the inner peripheral surface 21 of the bearing member 2, the values ​​before the shaft member 1 and the bearing member 2 slide can be used. As the above-mentioned rotation speed N, the rotation speed when the shaft member 1 is driven stably can be applied. As Λ lim , can be set to be greater than 2.0 and less than 4.0 according to the material properties of the shaft component 1 and the bearing component 2. In particular, when the surface roughness of the outer peripheral surface 11 of the shaft component 1 and the inner peripheral surface 21 of the bearing component 2 can be regarded as normal distribution, the minimum value of the oil film parameter Λ lim is 3.0. In addition, as Λ lim , assuming that even a value smaller than 3.0 can maintain the fluid lubrication state of the oil film 31 , it may be 2.5, for example.

[0084]

Formula 11

[0085]

[0086] The inner peripheral surface 21 receives the surface pressure from the outer peripheral surface 11 via the oil film 31. That is, the inner peripheral surface 21 has an area (surface pressure distribution) receiving the above-mentioned surface pressure. The surface pressure distribution, for example, is Figure 1The surface pressure distribution is formed in an arc shape along the inner peripheral surface 21 in a cross section perpendicular to the central axis P. The range and position of the surface pressure distribution can be changed according to the rotation and vibration state of the shaft member 1. The maximum load W is calculated as the total of the surface pressures in the surface pressure distribution of the inner peripheral surface 21.

[0087] The above parameter C n , preferably lower than the value γ(ε2) calculated by the above formula 2 using the eccentricity ε2 calculated by the following formula 4. γ(ε2) is calculated based on the eccentricity ε2 of the sliding member with a standard surface roughness of 0.40 μm for the arithmetic mean roughness of the outer peripheral surface of the shaft member and the arithmetic mean roughness of the inner peripheral surface of the bearing member. n Lower than γ(ε2), the above parameter C n By adjusting the above parameter C n By keeping the friction loss between the outer peripheral surface 11 and the inner peripheral surface 21 small, it is possible to further suppress the friction loss between the outer peripheral surface 11 and the inner peripheral surface 21.

[0088]

Formula 12

[0089]

[0090] As the above parameter C n , further preferably lower than the value γ(ε3) calculated according to the above formula 2 using the eccentricity ε3 calculated by the following formula 12, and further preferably lower than the value γ(ε4) calculated according to the above formula 2 using the eccentricity ε4 calculated by the following formula 13. γ(ε3) is calculated based on the eccentricity ε3 of the sliding member in which the arithmetic mean roughness of the outer peripheral surface of the shaft member and the arithmetic mean roughness of the inner peripheral surface of the bearing member are both 0.35 μm, and γ(ε4) is calculated based on the eccentricity ε4 of the sliding member in which the arithmetic mean roughness of the outer peripheral surface of the shaft member and the arithmetic mean roughness of the inner peripheral surface of the bearing member are both 0.30 μm.

[0091]

Formula 13

[0092]

[0093]

[0094] <Shaft member>

[0095] The shaft member 1 is a rotating body that rotates in the circumferential direction relative to the bearing member 2. Examples of the shaft member 1 include a marine crankshaft, an intermediate shaft, a propeller shaft, etc. that are arranged on a ship. Examples of the material of the shaft member 1 include carbon steel, low alloy steel, aluminum alloy, etc.

[0096] It is preferable not to form a coating such as a lubricating film on the outer peripheral surface 11 of the shaft member 1. By not providing a coating on the outer peripheral surface 11, it is possible to suppress the mixing of foreign matter between the outer peripheral surface 11 and the inner peripheral surface 21 and the increase in cost.

[0097] The lower limit of the shaft diameter D of the shaft member 1 is 0.18 m as mentioned above, but it can also be 0.28 m, 0.33 m, or 0.36 m. When the shaft diameter D of the shaft member 1 is greater than the above lower limit, if a coating is provided on the outer peripheral surface 11 of the shaft member 1, etc., there is a high possibility that the coating is damaged and impurities are generated. In contrast, since the sliding member does not need to provide a coating on the outer peripheral surface 11, it is possible to suppress the mixing of impurities in the above sliding area.

[0098] The upper limit of the shaft diameter D of the shaft member 1 is not particularly limited, but is preferably 1.5 m, more preferably 1.3 m, and further preferably 1.2 m. If the shaft diameter D of the shaft member 1 exceeds the upper limit, the friction loss between the outer peripheral surface 11 and the inner peripheral surface 21 may not be sufficiently suppressed.

[0099] The lower limit of the contact rate α is preferably 0.6, more preferably 0.7, and further preferably 0.8. When the shaft diameter D of the shaft member 1 is a large diameter shaft member 1 above the above lower limit, it is difficult to fully improve the contact rate between the shaft member and the bearing member only by machining. In this case, the contact rate α can be increased to above the above lower limit by manually grinding the part in contact with the bearing member in the shaft member using sandpaper or the like as a finishing process. As a method for determining the above contact portion and the above contact rate α, for example, a method using a stretcher, a method using a shell-shaped bearing model material, etc. can be cited. The stretcher has a plane extending along the axial direction of the shaft member. In this method, after the ink is applied to the above plane, the above plane is pressed against the outer peripheral surface of the shaft member to transfer the ink. Thereafter, the above contact portion is determined according to the transfer portion of the ink, and the above contact rate α is determined by the transfer rate of the ink. On the other hand, the shell-shaped bearing model material has an inner peripheral surface that partially surrounds the outer peripheral surface of the shaft member. The method of using the above-mentioned bearing model material is the same as the method of using the above-mentioned stretcher, that is, after the above-mentioned inner peripheral surface is coated with ink, the above-mentioned inner peripheral surface is pressed against the outer peripheral surface of the shaft member to transfer the ink, and the above-mentioned contact portion and the above-mentioned contact rate α are determined based on this. If the above-mentioned contact rate α is lower than the above-mentioned lower limit, it is possible that the outer peripheral surface 11 of the shaft member 1 and the inner peripheral surface 21 of the bearing member 2 may not be in uniform contact. As a result, the surface pressure of the outer peripheral surface 11 on the inner peripheral surface 21 caused by the above-mentioned maximum load W is likely to increase, so that the oil film 31 may be difficult to maintain a fluid lubrication state.

[0100] On the outer peripheral surface 11 of the shaft member 1, there may be a plurality of roughness protrusion vertices calculated according to the following steps. First, based on the roughness curve of a measurement length of 4.0 mm measured with a cutoff value of 0.25 mm in accordance with JIS-B0601 (2013), an average line of the roughness curve is set according to JIS-B0601 (2013). With the average line as a reference, the height of the measurement point located above the average line is defined as a positive value, and the height of the measurement point located below the average line is defined as a negative value. The average value of the heights of all measurement points with positive heights is taken as Thr0. Next, among the measurement points on the roughness curve, the measurement points that are higher than the measurement points adjacent to both sides and have a height greater than -Thr0 are taken as hypothetical vertices. The measurement point with the smallest height (the greatest depth from the adjacent hypothetical vertex) among the measurement points located between adjacent hypothetical vertices is taken as a valley. Then, among all hypothetical vertices, the height difference between the hypothetical vertex and the valley adjacent to both sides of the hypothetical vertex is obtained, and the vertex with the larger height difference less than 0.2×Thr0 is excluded. As a result, the remaining provisional vertices are obtained as the roughness protrusion vertices.

[0101] When the apex of the roughness protrusion is present on the outer peripheral surface 11 of the shaft member 1, the lower limit of the radius of curvature β of the roughness protrusion on the outer peripheral surface 11 may be 55 μm or 58 μm. When the outer peripheral surface 11 is manually polished as the above-mentioned finishing, the radius of curvature β of the roughness protrusion tends to become larger. If the radius of curvature β of the roughness protrusion is large, seizure is likely to occur between the outer peripheral surface 11 and the inner peripheral surface 21. Even in such a configuration, the sliding member can easily suppress seizure in the above-mentioned sliding domain.

[0102] In addition, the above-mentioned "curvature radius of the roughness protrusion" means the value calculated according to the following steps. First, draw a straight line from all the measurement points between the vertex of the above-mentioned roughness protrusion and the valleys adjacent to the vertex of the roughness protrusion on both sides, and define the measurement point with the largest gradient of this straight line as the end of the roughness protrusion. The quadratic coefficient of the quadratic function obtained by fitting the roughness curve between the two ends of each roughness protrusion according to the least squares method is taken as a, and the curvature radius of each roughness protrusion is obtained by -0.5 / a. The median of the curvature radius of all roughness protrusions on the above-mentioned roughness curve is obtained as the curvature radius of the roughness protrusion.

[0103] If the shaft component 1 is manually ground on the outer peripheral surface 11 as the above-mentioned finishing, the curvature radius β of the roughness protrusion tends to become larger. In addition, regarding other roughness characteristics of the outer peripheral surface 11, there is also a tendency for the roughness to increase. In this case, by using sandpaper with a sufficiently large number for grinding, the arithmetic mean roughness Ra1 of the outer peripheral surface 11 of the shaft component 1 can be reduced to less than 0.23μm, and the height Rpk1 of the protruding peaks of the outer peripheral surface 11 can be reduced to less than 0.19μm. For example, by using sandpaper with a roughness of 200 or more for grinding, the arithmetic mean roughness Ra1 and the height Rpk1 of the protruding peaks can be reduced to the above-mentioned range. The above-mentioned sandpaper number can be higher than 500 or higher than 600. In addition, the arithmetic mean roughness Ra1 of the outer peripheral surface 11 of the shaft component 1 and the height Rpk1 of the protruding peaks of the outer peripheral surface 11 can be the values ​​after grinding with the above-mentioned sandpaper and before the shaft component 1 and the bearing component 2 slide.

[0104] The upper limit of the arithmetic mean roughness Ra1 of the outer peripheral surface 11 is 0.23 μm as mentioned above, preferably 0.16 μm, more preferably 0.12 μm, and further preferably 0.08 μm. If the arithmetic mean roughness Ra1 of the outer peripheral surface 11 is higher than the above upper limit, it is possible that the oil film 31 will have difficulty maintaining the fluid lubrication state. The lower limit of the arithmetic mean roughness Ra1 of the outer peripheral surface 11 is not particularly limited, but can be 0.01 μm. In addition, as the arithmetic mean roughness Ra1 of the outer peripheral surface 11, the value before the shaft component 1 and the bearing component 2 slide can be used.

[0105] The upper limit of the height Rpk1 of the protruding peak of the outer peripheral surface 11 is 0.19 μm as mentioned above, preferably 0.18 μm, more preferably 0.14 μm, and further preferably 0.10 μm. If the height Rpk1 of the protruding peak of the outer peripheral surface 11 is higher than the above upper limit, it is possible that the oil film 31 will have difficulty maintaining a fluid lubrication state. The lower limit of the height Rpk1 of the protruding peak of the outer peripheral surface 11 is not particularly limited, but can be 0.01 μm. In addition, as the height Rpk1 of the protruding peak of the outer peripheral surface 11, the value before the shaft component 1 and the bearing component 2 slide can be used.

[0106] <Bearing components>

[0107] The bearing member 2 includes, for example, a marine crankshaft bearing, an intermediate bearing, a propulsion bearing, etc. The material of the bearing member 2 includes, for example, white metal, aluminum alloy, trimetal, kelmet, etc.

[0108] It is preferable that a coating such as a lubricating film is not formed on the inner peripheral surface 21 of the bearing member 2. By not providing a coating on the inner peripheral surface 21, it is possible to suppress the mixing of impurities between the outer peripheral surface 11 and the inner peripheral surface 21 and the increase in cost.

[0109] The upper limit of the width L of the inner peripheral surface 21 of the bearing member 2 in the axial direction is preferably 0.350 m, more preferably 0.300 m, and further preferably 0.220 m. If the width L is higher than the upper limit, the friction loss between the outer peripheral surface 11 and the inner peripheral surface 21 may not be sufficiently suppressed. On the contrary, the lower limit of the width L can be, for example, 0.010 m from the viewpoint of ensuring the strength of the bearing member 2.

[0110] The upper limit of the aspect ratio calculated as L / D is preferably 0.8, more preferably 0.6, and further preferably 0.4, if the aspect ratio is higher than the upper limit. n The calculated value of is difficult to match the state of the oil film 31, and thus, the friction loss between the outer peripheral surface 11 and the inner peripheral surface 21 may not be sufficiently suppressed. On the other hand, the lower limit of the aspect ratio can be, for example, 0.1 from the viewpoint of ensuring the strength of the bearing member 2.

[0111] The upper limit of the radius gap c is not particularly limited, but can be, for example, 1.0×10 -3 From the viewpoint of facilitating the formation of the oil film, the lower limit of the radial gap c can be, for example, 1.0×10 -4 m.

[0112] The hardness of the outer surface 11 and the inner surface 21 is different. Since the hardness of the outer surface 11 and the inner surface 21 of the sliding component is different, when the outer surface 11 and the inner surface 21 are in contact, the microscopic protrusions on the surface of the one with higher hardness among the two sliding surfaces are easily maintained. In contrast, the surface of the one with lower hardness among the outer surface 11 and the inner surface 21 is easily plastically deformed due to the rotational contact between the sliding surfaces. Therefore, the one with lower hardness among the outer surface 11 and the inner surface 21 can be regarded as a surface having substantially the same roughness protrusions as the one with higher hardness, or a smooth surface having substantially no roughness protrusions. In other words, the arithmetic mean roughness of the one with higher hardness among the outer surface 11 and the inner surface 21 is taken as Ra h [μm], it can be converted into Ra1=Ra2=Ra by the above formula 3 h , the arithmetic mean roughness of the one with lower hardness between the outer peripheral surface 11 and the inner peripheral surface 21 can also be converted to 0. In this way, by considering the sliding surface of the one with lower hardness between the outer peripheral surface 11 and the inner peripheral surface 21 as a surface with the same roughness protrusion as the one with higher hardness, or a smooth surface without roughness protrusion, ε1 of the above-mentioned formula 3 can be calculated more easily.

[0113] The hardness H1 [HV] of the shaft member 1 is preferably greater than the hardness H2 [HV] of the bearing member 2. Generally speaking, since the hardness H2 of the bearing member 2 is small, it is difficult to intentionally control the surface roughness of the inner peripheral surface 21 by machining or the like. In this case, by making the hardness H1 of the shaft member 1 greater than the hardness H2 of the bearing member 2, the inner peripheral surface 21 of the bearing member 2 can be ground by sliding with the shaft member 1. As a result, the surface roughness of the inner peripheral surface 21 of the bearing member 2 is reduced, and the friction resistance and seizure between the outer peripheral surface 11 and the inner peripheral surface 21 are easily suppressed. The lower limit of the ratio (H1 / H2) of the hardness H1 of the shaft member 1 to the hardness H2 of the bearing member 2 is preferably 4.1, more preferably 5.0, further preferably 6.0, and particularly preferably 8.0. If the above ratio is lower than the above lower limit, it may be difficult to reduce the surface roughness of the inner peripheral surface 21 by the rotation of the shaft member 1. On the other hand, the upper limit of the above ratio is not particularly limited, but is preferably 20, for example, from the viewpoint of facilitating the selection of the materials of the shaft member 1 and the bearing member 2 .

[0114] <Lubricating oil>

[0115] Examples of the lubricating oil 3 include paraffin-based base oils, etc. The lubricating oil 3 forms an oil film 31 , thereby making it easy to maintain a fluid lubrication state between the outer peripheral surface 11 and the inner peripheral surface 21 .

[0116] The upper limit of the viscosity η of the lubricating oil 3 is preferably 7.7×10 -3 Pa·second, more preferably 6.2×10 - 3 Pa·second, more preferably 5.2×10 -3 If the viscosity η is higher than the upper limit, the friction loss between the outer peripheral surface 11 and the inner peripheral surface 21 may not be sufficiently suppressed. On the contrary, the lower limit of the viscosity η can be, for example, 1.0×10 -3 Pa sec.

[0117] <Advantages>

[0118] The sliding member can suppress friction loss and seizure between the outer peripheral surface 11 and the inner peripheral surface 21 because the oil film 31 can easily maintain a fluid lubrication state. In addition, the sliding member can easily reduce friction loss under the condition that the oil film 31 is in a fluid lubrication state because the viscosity η, the rotation speed N, the width L, and the shaft diameter D can be easily controlled to be small.

[0119] [Method of driving the sliding member]

[0120] Figure 2A method for driving a sliding member using Figure 1 The sliding member includes a driving step S1 for rotating the shaft member 1.

[0121] <Drive process>

[0122] In the driving step S1, lubricating oil 3 is supplied to the gap between the shaft member 1 and the bearing member 2, and the shaft member 1 is rotated. As a method for supplying the lubricating oil 3, for example, a supply port for supplying the lubricating oil 3 is provided on the inner peripheral surface 21 of the bearing member 2, and the lubricating oil 3 is supplied from the supply port in a manner that the lubricating oil 3 circulates in the sliding area between the shaft member 1 and the bearing member 2.

[0123] During the stable driving of the driving step S1, the parameter C calculated by the above equation 1 indicating the state of the oil film 31 is n , is controlled to be above the reference value γ(ε1) calculated based on the above formula 2.

[0124] During stable driving of the driving step S1, the lower limit of the rotation speed N is preferably 0.30 rps, and more preferably 0.56 rps. If the rotation speed N is lower than the lower limit, the oil film 31 may be difficult to maintain a fluid lubrication state. The upper limit of the rotation speed N is preferably 30 rps, and more preferably 20 rps. If the rotation speed N is higher than the upper limit, the friction loss between the outer peripheral surface 11 and the inner peripheral surface 21 may not be fully suppressed.

[0125] <Advantages>

[0126] In the driving method of the sliding member, during the stable driving of the driving step S1, the above parameter C is set to n By controlling the value to be equal to or greater than the reference value γ(ε1), the friction loss and seizure between the shaft member 1 and the bearing member 2 can be suppressed.

[0127] [Other embodiments]

[0128] The above embodiments do not limit the configuration of the present invention. Therefore, the above embodiments may omit, replace or add the constituent elements of each part of the above embodiments based on the description of this specification and technical common sense, and all of these should be interpreted as belonging to the scope of the present invention.

[0129] In the above-mentioned embodiment, the central axis of the shaft member extends in the horizontal direction, but the central axis of the shaft member may be inclined with respect to the horizontal direction.

[0130] In the above embodiment, the outer circumferential surface of the shaft member and the inner circumferential surface of the bearing member have different hardnesses, but the hardnesses of the outer circumferential surface and the inner circumferential surface may be substantially the same. In this case, ε1 can be calculated using the arithmetic mean roughness of the outer circumferential surface and the inner circumferential surface according to the above formula 3.

[0131] In the driving process of the above embodiment, lubricating oil is supplied to the gap between the shaft member and the bearing member, and the shaft member is rotated, but lubricating oil may be dripped into the gap before the shaft member is rotated. In addition, when lubricating oil is dripped into the gap before the shaft member is rotated, lubricating oil may not be dripped during the rotation of the shaft member.

[0132] [Example]

[0133] Hereinafter, the present invention will be described in detail based on examples, but the present invention is not to be construed in a limitative manner based on the description of these examples.

[0134] In the present example, a seizure test for investigating conditions under which seizure occurs, a grinding test for manually grinding the outer peripheral surface of a shaft member, and a sliding test for rotating the shaft member were performed.

[0135] [Bite test]

[0136] In the bite test, a bearing life tester manufactured by Chihoda Seihei Co., Ltd. is used to rotate shaft components with different roughness. As the shaft component, a shaft component whose outer peripheral surface is manually polished is used. In addition, the inner peripheral surface of the bearing component that surrounds the outer peripheral surface of the shaft component all around is pressed against the above-mentioned shaft component with a certain load, and the shaft component is rotated. The shaft diameter of the shaft component is 39.96mm (tolerance is ±0.01mm), the inner diameter of the bearing component is 40.20mm (tolerance is +0.025mm to +0.050mm), and the axial width of the inner peripheral surface of the bearing component is 35.00mm. The load applied by the bearing component to the shaft component is 10kN. In the rotation speed of the shaft component, the initial rotation speed is 3000rpm, and it is gradually reduced by 250rpm each time at intervals of more than 1 minute and less than 10 minutes until the minimum rotation speed is 250rpm. When the outer peripheral surface of the shaft component and the inner peripheral surface of the bearing component are bitten, the rotation of the shaft component is stopped. As the shaft component, manganese steel is used, and as the bearing component, white alloy of WJ1 specified in JIS-H5401 (1958) is used. As the lubricating oil, "FBK OIL RO32" manufactured by ENEOS (Co., Ltd.) is used. The lubricating oil is supplied to the sliding area between the outer peripheral surface of the shaft component and the inner peripheral surface of the bearing component at an initial temperature of 70°C, and the sliding area is impregnated with the above-mentioned lubricating oil, and the above-mentioned lubricating oil is circulated. Figure 3 The relationship between the arithmetic mean roughness Ra of the outer peripheral surface of the shaft member and the rotation speed of the shaft member at the time when the seizure occurs is shown in FIG. Figure 4 ] represents the relationship between the height Rpk of the protruding peak of the outer peripheral surface of the shaft member and the rotation speed of the shaft member at the time when the seizure occurs. Figure 5 The arithmetic mean roughness of the shaft component and the time when the seizure occurs are shown in C n / γ(ε1). Figure 3 , Figure 4 and Figure 5 In the figure, white circles mean that no seizure occurs, and black circles mean that seizure occurs. Figure 5 C n , is to make the load W applied to the inner peripheral surface of the bearing member be 1.0×10 4 N, the contact rate α is 1, and the rotation speed N of the shaft member is calculated by the above formula 1 as the number of revolutions when the rotation of the shaft member stops. Figure 5 The γ(ε1) of the bearing member is the arithmetic mean roughness of the inner peripheral surface of the bearing member, which is considered to be consistent with the arithmetic mean roughness of the outer peripheral surface of the shaft member, and is based on the Λ lim ε1 calculated by the above formula 3 as 2.5 was calculated by the above formula 2. Considering that the shaft member with a very small shaft diameter was used for the test, the above contact ratio α was regarded as 1. In addition, the arithmetic mean roughness Ra and the protruding peak height Rpk of the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member were measured using a small surface roughness measuring instrument ("SJ-310") manufactured by Mitutoyo Co., Ltd.

[0137] like Figure 3 As shown in FIG. 1 , if the arithmetic mean roughness Ra of the shaft component is controlled to be less than 0.23 μm, seizure is unlikely to occur. Figure 4 As shown in FIG. 1 , if the height Rpk of the protruding peak of the shaft member is controlled to be less than 0.19 μm, seizure is unlikely to occur. Therefore, it is considered that the arithmetic mean roughness Ra of the shaft member is controlled to be less than 0.23 μm, and the height Rpk of the protruding peak of the shaft member is controlled to be less than 0.19 μm, so that the sliding surface is easy to maintain a fluid lubrication state.

[0138] In addition, if Figure 5 As shown, C n When / γ(ε1) is less than 1, seizure is likely to occur. Therefore, it is considered that the parameter C calculated by the above formula 1 is n When the reference value γ(ε1) calculated by the above-mentioned formula 2 is satisfied or greater, seizure can be more easily suppressed.

[0139] [Grinding test]

[0140] In the grinding test, the outer peripheral surface of the shaft component is ground with sandpaper. The material of the shaft component is a steel material equivalent to S45C specified in JIS-G4051 (2016). The shaft diameter of the shaft component of the grinding part is 600mm. The grinding is repeated while gradually increasing the sandpaper number. For each sandpaper number, a small surface roughness measuring instrument ("SJ-310") manufactured by Mitutoyo Co., Ltd. is used to measure the arithmetic mean roughness Ra and the height of the protruding peak Rpk of the above-mentioned outer peripheral surface after grinding. In this measurement, four circumferential positions are determined at intervals of 90 degrees along the circumference of the above-mentioned outer peripheral surface, and the arithmetic mean roughness Ra and the height of the protruding peak Rpk of the above-mentioned outer peripheral surface are measured at two measurement positions at different axial positions for each circumferential position. In addition, the evaluation length of the above-mentioned measurement position is 4 mm. Figure 6 The measurement results of the arithmetic mean roughness Ra1 are shown in Figure 7 The measurement results of the protruding peak height Rpk1 are shown in FIG. Figure 6 and Figure 7 The plots in the figure represent the mean, and the error bars represent the error range relative to the mean.

[0141] like Figure 6 As shown in FIG. 1 , when the sandpaper number is greater than 200, the arithmetic mean roughness Ra is reduced to a range below 0.23 μm. Figure 7 As shown in the figure, if the size of the sandpaper number reaches 200 or more, the height Rpk of the protruding peak of the outer peripheral surface of the shaft member is easily reduced to a range of 0.19 μm or less. In addition, if the size of the sandpaper number is higher than 500, the height Rpk of the protruding peak of the outer peripheral surface of the shaft member is reduced to a range of 0.19 μm or less. Therefore, by making the size of the sandpaper number 200 or more, the roughness of the outer peripheral surface of the shaft member can be controlled to a range where seizure is difficult to occur in the above-mentioned seizure test.

[0142] [Sliding test]

[0143] In the sliding test, apparatus A (friction and wear testing machine manufactured by Chihoda Seiho Co., Ltd.), apparatus B (bearing life testing machine manufactured by Chihoda Seiho Co., Ltd.) and apparatus C (friction and wear testing machine manufactured by Kobelco Seiho Co., Ltd.) were used to rotate the shaft member under the following conditions No. 1 to No. 20. As the shaft member, a shaft member whose outer peripheral surface was manually polished was used. In apparatus A, the bearing member on the flat plate was pressed against the above-mentioned shaft member with a certain load, and the shaft member was rotated. In apparatus B and apparatus C, the inner peripheral surface of the bearing member that surrounds the outer peripheral surface of the shaft member throughout the entire circumference was pressed against the above-mentioned shaft member with a certain load, and the shaft member was rotated. In apparatus B, the same bearing life testing machine as that used in the above-mentioned bite test was used. In addition, for No. 1 to No. 20, the hardness of the shaft member and the shaft member, as well as the arithmetic mean roughness and the height of the protruding peaks of the shaft member and the shaft member before and after the sliding test were measured. Table 1 shows the measurement results of No. 1 to No. 20. However, in Table 1, Ra 1A Indicates the arithmetic mean roughness of the shaft component before the sliding test, Ra 1B Indicates the arithmetic mean roughness of the shaft component after the sliding test, Ra 2A Indicates the arithmetic mean roughness of the bearing component before the sliding test, Ra 2B Indicates the arithmetic mean roughness of the bearing component after the sliding test. In Table 1, Rpk 1A Indicates the protruding peak height of the shaft component before the sliding test, Rpk 1B Indicates the protruding peak height of the shaft component after the sliding test, Rpk 2A Indicates the protruding peak height of the bearing component before the sliding test, Rpk 2B Indicates the height of the protruding peak after the sliding test of the bearing component. In this sliding test, the hardness is measured using a Vickers hardness tester ("FV-310") manufactured by Future-tec Co., Ltd. for the shaft component, and a Vickers hardness tester ("MVK-E") manufactured by Akashi Manufacturing Co., Ltd. for the bearing component. In addition, the arithmetic mean roughness and the height of the protruding peak are measured using a small surface roughness measuring instrument ("SJ-310") manufactured by Mitutoyo Co., Ltd. In addition, in the measurement of the arithmetic mean roughness and the height of the protruding peak, the evaluation length is 4 mm.

[0144] (No.1 to No.3)

[0145] In No. 1 to No. 3, the load applied by the bearing component to the shaft component is 10 kN. The rotation speed of the shaft component is set to an initial rotation speed of 3000 rpm, and is gradually reduced by 250 rpm at intervals of 10 minutes until the minimum rotation speed reaches 250 rpm. Manganese steel is used as the shaft component, and white alloy of WJ1 specified in JIS-H5401 (1958) is used as the bearing component. As the lubricating oil, "FBK OILRO32" manufactured by ENEOS (Co., Ltd.) is used. The lubricating oil is supplied to the sliding area between the outer peripheral surface of the shaft component and the inner peripheral surface of the bearing component at an initial temperature of 70°C, and the sliding area is impregnated with the above-mentioned lubricating oil, and the above-mentioned lubricating oil is circulated.

[0146] (No.4 to No.12)

[0147] In No. 4 to No. 12, the rotation speed of the shaft component was kept constant at 3500 rpm. The load applied to the shaft component by the bearing component was set to an initial load of 0 kN, and was gradually increased by 0.5 kN at intervals of 5 minutes until a maximum of 20 kN was reached. Manganese steel was used as the shaft component, and white alloy equivalent to WJ1 specified in JIS-H5401 (1958) was used as the bearing component. As the lubricating oil, "FBK OIL RO32" manufactured by ENEOS (KK) was used. The lubricating oil was supplied to the sliding area between the outer peripheral surface of the shaft component and the inner peripheral surface of the bearing component at an initial temperature of 70°C, and the sliding area was circulated.

[0148] (No.13)

[0149] In No. 13, the rotation speed of the shaft component is set to 400 rpm. The load applied from the bearing component to the shaft component is set to an initial load of 0 kN, and is gradually increased by 0.1 kN at intervals of 1 minute until it reaches 1 kN. As the shaft component, S45C steel specified in JIS-G4051 (2016) is used, and as the bearing component, WJ2 white alloy specified in JIS-H5401 (1958) is used. As the lubricating oil, "FBK OIL RO32" manufactured by ENEOS (Co., Ltd.) is used. The lubricating oil is supplied to the sliding area between the outer peripheral surface of the shaft component and the inner peripheral surface of the bearing component at room temperature, and the sliding area is circulated.

[0150] (No.14 and No.17)

[0151] In No. 14 and No. 17, the rotation speed of the shaft member was set to 50 rpm, the load applied from the bearing member to the shaft member was kept fixed at 1 kN, and the shaft member was rotated for 240 minutes. In No. 14 and No. 17, except for the rotation speed, load and rotation time of the shaft member, the structure and driving conditions were the same as those of No. 13.

[0152] (No.15 and No.18)

[0153] In No. 15 and No. 18, the rotation speed of the shaft member was set to 100 rpm, the load applied from the bearing member to the shaft member was kept fixed at 1 kN, and the shaft member was rotated for 240 minutes. In addition, the lubricating oil was dripped once at room temperature to the sliding area between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member at the beginning of the sliding test. In No. 15 and No. 18, except for the rotation speed of the shaft member, the load, the rotation time and the lubricating oil supply method, the same structure and the same driving conditions as No. 13.

[0154] (No.16)

[0155] In No. 16, the rotation speed of the shaft member was set to 400 rpm. In No. 16, except for the rotation speed of the shaft member, the same configuration and the same driving conditions were used as in No. 13.

[0156] (No.19 and No.20)

[0157] No. 19 and No. 20 have the same configuration as No. 1 to No. 3 except that nickel-chromium-molybdenum alloy steel is used as the shaft member. In addition, No. 19 and No. 20 have the same driving conditions as No. 1 to No. 3 except that the rotation speed of the shaft member is reduced at 1-minute intervals.

[0158]

Table 1

[0159]

[0160] As shown in Table 1, the arithmetic mean roughness and the protruding peak height of the shaft member did not change significantly before and after the sliding test. On the other hand, the arithmetic mean roughness and the protruding peak height of the bearing member tended to decrease after the sliding test.

[0161] In No. 1 to No. 20, the ratio (H1 / H2) of the hardness H1 [HV] of the shaft member to the hardness H2 [HV] of the bearing member is used as the horizontal axis, and the difference in arithmetic mean roughness Ra after the sliding test is used as the horizontal axis. 2B ―Ra 1B The graph as the vertical axis is shown in Figure 8 In addition, H1 / H2 is used as the horizontal axis to highlight the difference in peak height Rpk 2B ―Rpk 1B The graph as the vertical axis is shown in Fig. 9 In addition, Figure 8 and Fig. 9The plot in the figure shows the average value, and the error bar shows the error range relative to the average value. In addition, in No. 13 to No. 15, the average value of H1 / H2 is taken, and the value of H1 / H2 is 5.2.

[0162] Depend on Figure 8 and Fig. 9 It can be seen that if the hardness ratio H1 / H2 reaches 4.1 or more, the difference in arithmetic mean roughness Ra 2B ―Ra 1B The difference between the height of the protruding peak and the height of the protruding peak is Rpk 2B ―Rpk 1B It shows a tendency to approach 0. It is understood that by setting the hardness ratio H1 / H2 to 4.1 or more, the bearing member is polished, and as a result, the arithmetic mean roughness and the protruding peak height of the bearing member are close to the arithmetic mean roughness and the protruding peak height of the shaft member, respectively.

[0163] In addition, it is shown below that friction loss can be reduced by reducing the arithmetic mean roughness of the outer peripheral surface of the shaft component and the inner peripheral surface of the bearing component. In Table 2, sliding conditions of No. 21 to No. 32 are assumed. In Table 2, the sliding conditions of No. 21, No. 27 and No. 30 are equivalent to those of existing sliding components. Table 2 also shows that under each sliding condition, the eccentricity ε1, the eccentricity ε2, the parameter C n Ratio to the reference value γ(ε1), parameter C n Ratio to γ(ε2), limiting oil film thickness h lim [μm], calculated value of friction coefficient μ. Here, parameter C n The limit oil film thickness h is calculated by the above formula 1, the eccentricity ε1 is calculated by the above formula 3, the eccentricity ε2 is calculated by the above formula 4, the reference values ​​γ(ε1) and γ(ε2) are calculated by applying the eccentricity ε1 and the eccentricity ε2 in the above formula 2, and the limit oil film thickness h is calculated by the above formula 1. lim Calculated by the following formula 14, the friction coefficient μ is calculated by the above formula 6. In addition, when calculating ε1 and ε2 by the above formula 3 and the above formula 4, the oil film parameter Λ lim The "limiting oil film thickness" refers to the minimum oil film thickness at which the oil film can maintain a fluid lubrication state.

[0164]

Formula 14

[0165]

[0166]

[0167] (No.21 to No.26)

[0168] As shown in Table 2, the shaft diameter D of No. 21 to No. 26 is 0.90m. No. 22 controls the rotation speed N to be smaller than that of the existing sliding member (No. 21), but the arithmetic mean roughness of the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member are both 0.40μm, which is equivalent to No. 21. n / γ(ε1) is less than 1, so there is a possibility that the fluid lubrication state cannot be maintained. On the other hand, the arithmetic mean roughness of the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member is lower than that of the existing sliding member (No. 21) in No. 23 to No. 26, C n / γ(ε1) satisfies 1 or more. Therefore, it is highly likely that No. 23 to No. 26 can maintain the fluid lubrication state. In addition, in No. 23, by reducing the rotation speed, and in No. 24 to No. 26, by reducing the axial width L (bearing width L) of the inner peripheral surface of the bearing member and increasing the contact ratio α, C n / γ(ε2) is less than 1. Therefore, the friction coefficients of No.23 to No.26 are lower than that of No.21.

[0169] (No.27 to No.29)

[0170] As shown in Table 2, in No. 27 to No. 29, the bearing width L is 0.200 m. No. 28 controls the shaft diameter D and the viscosity η of the lubricating oil to be smaller than those of the existing sliding member (No. 27), but the arithmetic mean roughness of the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member are both equivalent to 0.40 μm of No. 27. Therefore, No. 28 has a C n / γ(ε1) is less than 1, and the fluid lubrication state may not be maintained. On the other hand, No. 29, in which the arithmetic mean roughness of both the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member is lower than that of No. 27, n / γ(ε1) satisfies 1 or more. Therefore, it is highly likely that No.29 can maintain the fluid lubrication state. In addition, No.29 reduces the shaft diameter D and the viscosity η of the lubricating oil, C n / γ(ε2) is less than 1. Therefore, the friction coefficient of No.29 is lower than that of No.27.

[0171] (No.30 to No.32)

[0172] As shown in Table 2, the shaft diameter D of No. 30 to No. 32 is 0.18 m. No. 31 controls the bearing width L to be smaller than the existing sliding member (No. 30), but the arithmetic mean roughness of the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member are both 0.40 μm, which is equivalent to No. 30. Therefore, No. 31 has a C n / γ(ε1) is less than 1, so there is a possibility that the fluid lubrication state cannot be maintained. On the other hand, the arithmetic mean roughness of the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member of No. 32 is lower than that of No. 30. n / γ(ε1) satisfies 1 or more. Therefore, it is highly likely that No.32 can maintain the fluid lubrication state. In addition, No.32 reduces the bearing width L compared to No.30, so C n / γ(ε2) is less than 1. Therefore, No.32 has a lower friction coefficient than No.30.

[0173] According to the comparison of No.21 to No.26, the comparison of No.27 to No.29, and the comparison of No.30 to No.32, γ(ε1)≤C n A sliding member with γ(ε2) <γ(ε2) can maintain a fluid lubrication state while suppressing friction loss compared to conventional sliding members.

[0174]

Industrial Applicability

[0175] The sliding member according to one embodiment of the present invention can suppress frictional resistance and seizure between a shaft member and a bearing member, and thus can be suitably used as a sliding member for ships, for example.

Claims

1. A sliding member comprising: Shaft components with a shaft diameter D of 0.18m or more; a bearing member capable of slidably supporting the outer peripheral surface of the shaft member; Lubricating oil is supplied to a gap between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member to form an oil film in the gap, in, The arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member is 0.23 μm or less, and the protruding peak height Rpk1 of the outer peripheral surface of the shaft member is 0.19 μm or less, The arithmetic mean roughness Ra1 means a value measured according to JIS-B0601 (2013) with a low-pass cutoff value λc of 2.5 mm and a high-pass cutoff value λs of 0.8 μm. The protruding peak height means a value measured according to JIS-B0671-2 (2002). When the axial width of the inner peripheral surface of the bearing member is L, the aspect ratio calculated by L / D is less than 1, and the unit of L is m. The parameter C calculated by the following formula 1 represents the state of the oil film: n Greater than or equal to the reference value γ(ε1) calculated based on the following formula 2, In the above formula 1, α represents the contact ratio between the shaft member and the bearing member, which means the proportion of the portion of the total sliding area where the two members are in solid contact when the shaft member and the bearing member slide without supplying lubricating oil; η represents the viscosity of the lubricating oil, which is calculated by the following formula 7 using the density ρ of the lubricating oil and the kinematic viscosity ν(T) of the lubricating oil at temperature T, wherein the unit of η is Pa·second, and the unit of the density ρ is g / cm 3 The unit of the temperature T is K, and the unit of the kinematic viscosity ν(T) is mm 2 / second; N represents the rotation speed of the shaft component, and the unit is rps; W represents the maximum load applied from the outer circumference of the shaft component to the inner circumference of the bearing component, and the unit is N; c represents the radius gap between the shaft component and the bearing component, which means the value of the radius of the bearing component minus the radius of the shaft component, and the unit is m; γ (ε) in the above formula 2 is the roughness parameter of the outer circumference of the shaft component and the inner circumference of the bearing component expressed as a function of the eccentricity ε, and the eccentricity ε means the value obtained by dividing the eccentricity between the center axis of the shaft component and the center axis of the bearing component when there is a load on the shaft component by the radius gap, and ε1 represents that, when the arithmetic mean roughness of the inner circumference of the bearing component is set to Ra2, the minimum oil film parameter value for the oil film to maintain the fluid lubrication state is Λ lim , the value calculated by the following formula 3, wherein Ra2 means the value measured according to JIS―B0601 (2013) with a low-pass cutoff value λc2.5mm and a high-pass cutoff value λs0.8μm, the unit of Ra2 is μm, and the minimum oil film parameter Λ lim The value of is 3, n=ρν(T)×10 －3 …7.

2. The sliding member according to claim 1, wherein: The outer circumferential surface of the shaft member and the inner circumferential surface of the bearing member have different hardnesses, and the arithmetic mean roughness of the one with higher hardness between the outer circumferential surface of the shaft member and the inner circumferential surface of the bearing member is defined as Ra. h When Ra1=Ra2=Ra in the above formula 3 h , where Ra h The unit is μm.

3. The sliding member according to claim 1 or claim 2, wherein: The contact ratio α is greater than or equal to 0.

6.

4. The sliding member according to claim 1 or claim 2, wherein: The parameter C n is lower than the value γ(ε2) calculated from the above formula 2 using the eccentricity ε2 calculated by the following formula 4, 。 5. A method for driving a sliding member, wherein: The sliding member comprises: a shaft member having a shaft diameter D of 0.18 m or more; a bearing member capable of slidably supporting the outer peripheral surface of the shaft member; and lubricating oil supplied to a gap between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member to form an oil film in the gap. The sliding member driving method includes a driving step of rotating the shaft member using the sliding member. The arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member is 0.23 μm or less, and the protruding peak height Rpk1 of the outer peripheral surface of the shaft member is 0.19 μm or less, The arithmetic mean roughness Ra1 means a value measured according to JIS-B0601 (2013) with a low-pass cutoff value λc of 2.5 mm and a high-pass cutoff value λs of 0.8 μm. The protruding peak height means a value measured according to JIS-B0671-2 (2002). When the width of the inner peripheral surface of the bearing member in the axial direction is L, the aspect ratio calculated by L / D is less than 1, and the unit of L is m. During the stable driving of the driving process, the parameter C calculated by the following formula 1 indicating the state of the oil film is n Control is to be greater than or equal to the reference value γ(ε1) calculated based on the following equation 2: In the above formula 1, α represents the contact ratio between the shaft member and the bearing member, which means the proportion of the portion of the total sliding area where the two members are in solid contact when the shaft member and the bearing member slide without supplying lubricating oil; η represents the viscosity of the lubricating oil, which is calculated by the following formula 7 using the density ρ of the lubricating oil and the kinematic viscosity ν(T) of the lubricating oil at temperature T, wherein the unit of η is Pa·second, and the unit of the density ρ is g / cm 3 The unit of the temperature T is K, and the unit of the kinematic viscosity ν(T) is mm 2 / second; N represents the rotation speed of the shaft component, and the unit is rps; W represents the maximum load applied from the outer circumference of the shaft component to the inner circumference of the bearing component, and the unit is N; c represents the radius gap between the shaft component and the bearing component, which means the value of the radius of the bearing component minus the radius of the shaft component, and the unit is m; γ (ε) in the above formula 2 is the roughness parameter of the outer circumference of the shaft component and the inner circumference of the bearing component expressed as a function of the eccentricity ε, and the eccentricity ε means the value obtained by dividing the eccentricity between the center axis of the shaft component and the center axis of the bearing component when there is a load on the shaft component by the radius gap, and ε1 represents that, when the arithmetic mean roughness of the inner circumference of the bearing component is set to Ra2, the minimum oil film parameter value for the oil film to maintain the fluid lubrication state is Λ lim , the value calculated by the following formula 3, wherein Ra2 means the value measured according to JIS―B0601 (2013) with a low-pass cutoff value λc2.5mm and a high-pass cutoff value λs0.8μm, the unit of Ra2 is μm, and the minimum oil film parameter Λ lim The value of is 3, n=ρν(T)×10 －3 …7.

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