Bearing device and method for driving bearing device

Abstract

To provide a bearing device capable of suppressing friction resistance and seizure between a shaft member and a bearing member while suppressing mixing of impurities and increase in cost.SOLUTION: A bearing device includes a shaft member 1 whose shaft diameter is 180 mm or more, a bearing member 2 for slidably supporting an outer peripheral surface of the shaft member, and a lubricant supplied to a gap between the outer peripheral surface 11 of the shaft member and an inner peripheral surface 21 of the bearing member, which forms an oil film in the gap. Arithmetic average roughness Ra1 of the outer peripheral surface of the shaft member is 0.05-0.30 μm, and a projection crest part height Rpk1 of the outer peripheral surface is 0.04-0.34 μm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a bearing device and a method for driving a bearing device. [Background technology]

[0002] A bearing device for a ship includes a shaft member such as a crankshaft, an intermediate shaft, or a propeller shaft, and a bearing member such as a plain bearing that slidably supports the shaft member. Lubricating oil is supplied to the gap between the shaft member and the bearing member. This lubricating oil forms an oil film between the shaft member and the bearing member, thereby reducing frictional resistance between the two members.

[0003] When the oil film is sufficiently formed, frictional resistance is likely to be maintained low because the viscosity of the oil film is the main factor in frictional resistance. On the other hand, when the oil film is not sufficiently formed, frictional resistance is likely to increase because the solid contact between the shaft member and the bearing member can also be a factor in frictional resistance in addition to the viscosity of the oil film. Furthermore, when the oil film is not sufficiently formed, seizure is likely to occur between the shaft member and the bearing member.

[0004] As a technique for reducing the frictional resistance and seizure of a sliding member, for example, Patent Document 1 describes forming an amorphous carbon coating containing nitrogen on the sliding surface, and Patent Document 2 describes a combined sliding member having surface properties that can accommodate the reduction in friction in internal combustion engines. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-025396 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-116707 Summary of the Invention [Problem to be solved by the invention]

[0006] However, if the coating described in Patent Document 1 is formed on the surface of a bearing member for a ship that is subjected to a high-load environment, for example, damage to the coating may cause impurities to be mixed into the lubricating oil. Furthermore, forming the coating on the surface of a bearing member for a large ship may increase capital investment and costs. Meanwhile, the technology described in Patent Document 2 is based on the premise that the sliding member reciprocates. Therefore, if the technology is applied to a bearing device that is based on the premise that the shaft member rotates, frictional resistance and seizure between the shaft member and the bearing member may not be suppressed.

[0007] The present invention has been made based on these circumstances, and aims to provide a bearing device that can suppress frictional resistance and seizure between the shaft member and the bearing member while suppressing the inclusion of impurities and increases in costs. [Means for solving the problem]

[0008] A bearing device according to one embodiment of the present invention, which has been made to solve the above-mentioned problems, is a bearing device comprising a shaft member having a shaft diameter of 180 mm or more, a bearing member that slidably supports the outer peripheral surface of the shaft member, and lubricating oil that 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 this gap, wherein the arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member is 0.05 μm or more and 0.30 μm or less, and the protruding peak height Rpk1 of the outer peripheral surface is 0.04 μm or more and 0.34 μm or less. [Effects of the Invention]

[0009] A bearing device according to one aspect of the present invention can suppress frictional resistance and seizure between the shaft member and the bearing member while suppressing the inclusion of impurities and increases in costs. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a cross section perpendicular to the central axis of a shaft member in a bearing device according to one embodiment of the present invention. [Figure 2]FIG. 2 is a flowchart showing a method for driving a bearing device according to one embodiment of the present invention. [Figure 3] FIG. 3 is a graph showing the relationship between the grit size of the sandpaper used to polish the shaft member and the arithmetic mean roughness of the shaft member. [Figure 4] FIG. 4 is a graph showing the relationship between the grit size of the sandpaper used to polish the shaft member and the height of the protruding peaks of the shaft member. [Figure 5] FIG. 5 is a graph showing the relationship between the hardness ratio of the shaft member to the bearing member and the ratio of the arithmetic mean roughness before and after the sliding test for the shaft member and the bearing member. [Figure 6] FIG. 6 is a graph showing the relationship between the hardness ratio of the shaft member to the bearing member and the ratio of the height of the protruding ridges of the shaft member and the bearing member before and after the sliding test. [Figure 7] FIG. 7 is a graph showing the relationship between the bearing characteristic numbers and the friction coefficient for Nos. 29, 30, 34, and 35. [Figure 8] FIG. 8 is a graph showing the relationship between the bearing characteristic numbers and the friction coefficient for Nos. 31, 32, 33, 36, 37, and 38. [Figure 9] FIG. 9 is a graph showing the relationship between the bearing characteristic numbers and the friction coefficient for No. 85 to No. 91. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Description of the embodiment of the present invention] First, embodiments of the present invention will be listed and described.

[0012] A bearing device according to one embodiment of the present invention comprises a shaft member having a shaft diameter of 180 mm or more, a bearing member that slidably supports the outer peripheral surface of the shaft member, and lubricating oil that 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 this gap, wherein the arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member is 0.05 μm or more and 0.30 μm or less, and the protruding peak height Rpk1 of the outer peripheral surface is 0.04 μm or more and 0.34 μm or less.

[0013] In this bearing device, the arithmetic mean roughness Ra1 and the peak height Rpk1 of the outer peripheral surface of the shaft member are optimized, which makes it easy to maintain a fluid lubrication state in the sliding area between the shaft member and the bearing member. Therefore, the bearing device can suppress frictional resistance and seizure between the shaft member and the bearing member while suppressing the inclusion of impurities in the sliding area and increasing costs.

[0014] When the hardness of the shaft member is H1 [HV] and the hardness of the bearing member is H2 [HV], it is preferable that H1 / H2 be 4.1 or more. By having H1 / H2 be equal to or greater than the lower limit, the surface roughness of the bearing member tends to be small. This makes it possible to further suppress frictional resistance and seizure between the shaft member and the bearing member.

[0015] When the arithmetic mean roughness of the inner peripheral surface of the bearing member is Ra2 [μm] and the height of the protruding peaks on the inner peripheral surface of the bearing member is Rpk2 [μm], it is preferable that Ra2 / Ra1 is 0.26 or more and 38.0 or less, and Rpk2 / Rpk1 is 0.32 or more and 69.0 or less. By controlling Ra2 / Ra1 and Rpk2 / Rpk1 within the above ranges in this manner, frictional resistance and seizure between the shaft member and the bearing member can be further suppressed.

[0016] The oil film thickness h [μm] calculated by the following formula 1 is the limit oil film thickness h calculated by the following formula 2. lim [μm] or more is preferable.

[0017]

number

[0018] In this way, the oil film thickness h is equal to the limit oil film thickness h lim As a result, it becomes easy to maintain the sliding area in a fluid lubricated state.

[0019] The viscosity η of the lubricating oil is the limiting viscosity η of the lubricating oil calculated by the following formula 3: lim [Pa·sec] or higher is preferable.

[0020]

number

[0021] In this way, the viscosity η of the lubricating oil is equal to the limit viscosity η of the lubricating oil. lim As a result, it becomes easier to maintain the sliding area in a fluid lubricated state.

[0022] The circumferential speed u of the shaft member is the limit circumferential speed u of the shaft member calculated by the following formula 4. lim [m / sec] or more is preferable.

[0023]

number

[0024] In this way, the peripheral speed u of the shaft member is equal to the critical peripheral speed u lim As a result, it becomes easier to maintain the sliding area in a fluid lubricated state.

[0025] The equivalent radius R of the shaft member and the bearing member is the limit equivalent radius R of the shaft member and the bearing member calculated by the following formula 5. lim [m] or more is preferable.

[0026]

number

[0027] In this way, the above equivalent radius R is equal to the above limit equivalent radius R lim As a result, it becomes easier to maintain the sliding area in a fluid lubricated state.

[0028] The viscosity η of the lubricating oil preferably satisfies the following formula 6. 0.08×ηlim ≦η<5.20×η lim 6

[0029] In this way, when the viscosity η satisfies the above formula 6, it becomes easy to maintain the sliding region in a fluid lubricated state while optimizing the viscosity of the lubricating oil.

[0030] A method for driving a bearing device according to another aspect of the present invention comprises a driving step of rotating the shaft member using a bearing device including a shaft member having a shaft diameter of 180 mm or more, a bearing member that slidably supports the outer peripheral surface of the shaft member, and lubricating oil that is supplied to a gap between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member and forms an oil film in this gap, wherein the arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member is 0.05 μm or more and 0.30 μm or less, and the protruding peak height Rpk1 of the outer peripheral surface is 0.04 μm or more and 0.34 μm or less.

[0031] By using the bearing device, the method for driving the bearing device can easily maintain a fluid lubrication state in the sliding area between the shaft member and the bearing member during the driving step, thereby suppressing frictional resistance and seizure between the shaft member and the bearing member while suppressing the inclusion of impurities in the sliding area and increasing costs.

[0032] In the present invention, "shaft diameter" refers to the diameter of the outer surface of a shaft member, "arithmetic mean roughness" refers to a value measured in accordance with JIS-B0601 (2013), "peak height" refers to a value measured in accordance with JIS-B0671-2 (2002), "hardness" refers to Vickers hardness measured in accordance with JIS-Z2244 (2009), "hydrodynamic lubrication state" refers to a state of hydrodynamic lubrication classified using the Stribeck curve, "critical oil film thickness" refers to the minimum oil film thickness at which the oil film can maintain a hydrodynamic lubrication state, "critical viscosity" refers to the minimum viscosity of the lubricating oil at which the oil film can maintain a hydrodynamic lubrication state, "circumferential speed of the shaft member" refers to the hydrodynamic speed on the outer surface of the shaft member, and "critical hydrodynamic speed" refers to the minimum hydrodynamic speed of the shaft member at which the oil film can maintain a hydrodynamic lubrication state.

[0033] In the present invention, the "equivalent radius" means a value [m] calculated by the following formula (7) when the radius of the outer peripheral surface of the shaft member is R1 [m] and the radius of the inner peripheral surface of the bearing member is R2 [m] (see FIG. 1 for the radii R1 and R2). The "critical equivalent radius" means the minimum equivalent radius at which the oil film can maintain a fluid lubrication state.

[0034]

Equation

[0035] In the present invention, the viscosity η of the lubricating oil is such that when the density of the lubricating oil is ρ [g / cm 3 , the kinematic viscosity of the lubricating oil at the lubricating oil temperature T [K] under atmospheric pressure is μ(T) [mm 2 / s], and the pressure applied to the lubricating oil is P [GPa], it means the value calculated by the following formula (8). η = ρη(T) exp(αP) × 10 -3 ···8

[0036] In the above formula (8), the kinematic viscosity μ(T) is calculated by the following formula (9) using the viscosity-temperature characteristic number m.

Equation

[0037] In the above formula (9), the viscosity-temperature characteristic number m is calculated by the following formula (10) shown in "Method for Estimating Kinematic Viscosity and Mixing Ratio" of JIS-K2283 (2000) using the known kinematic viscosity μ1 of the lubricating oil at the temperature T1 [K] and the known kinematic viscosity μ2 of the lubricating oil at the temperature T2 [K] (T1 < T2). m = {loglog(μ1 + 0.7) - loglog(μ2 + 0.7)} / (logT2 - logT1) ··· 10

[0038] In the above formula (9), b is calculated by the following formula (11) using the known kinematic viscosity μ3 of the lubricating oil at the temperature T3 [K]. b = loglog(μ3 + 0.7) + m logT3 ··· 11

[0039] In the present invention, the viscosity pressure coefficient α means a value [1 / GPa] calculated by the following empirical formula 12 using the viscosity temperature characteristic number m and the kinematic viscosity μ(T). α=m{0.1657+0.2332logμ(T)}×10...12

[0040] In the present invention, the "equivalent modulus of longitudinal elasticity" refers to the value [GPa] calculated by the following formula 13 when the Poisson's ratio of the shaft member is v1, the modulus of longitudinal elasticity of the shaft member is E1 [GPa], the Poisson's ratio of the bearing member is v2, and the modulus of longitudinal elasticity of the bearing member is E2 [GPa].

[0041]

number

[0042] In the present invention, the "oil film parameter" refers to the value of Λ calculated by the following formula 14 when the oil film thickness is h [μm].

[0043]

number

[0044] [Details of the embodiment of the present invention] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0045] [Bearing device] The bearing device of Figure 1 comprises a shaft member 1, a bearing member 2 that slidably supports the outer peripheral surface 11 of the shaft member 1, and lubricating oil 3 that is supplied to the gap between the outer peripheral surface 11 of the shaft member 1 and the inner peripheral surface 21 of the bearing member 2 and forms an oil film 31 in this gap.

[0046] <Shaft member> The shaft member 1 is a rotating body that rotates in a circumferential direction relative to the bearing member 2. Examples of the shaft member 1 include crankshafts, intermediate shafts, and propeller shafts for ships. Examples of materials for the shaft member 1 include carbon steel, low-alloy steel, and aluminum alloy. The central axis P of the shaft member 1 extends horizontally (Y direction in FIG. 1).

[0047] It is preferable that no coating layer, such as a lubricating film, is formed on the outer peripheral surface 11 of the shaft member 1. By not providing a coating layer on the outer peripheral surface 11 in this way, it is possible to prevent impurities from entering the sliding area between the shaft member 1 and the bearing member 2 and to prevent an increase in costs.

[0048] The shaft diameter of the shaft member 1 is 180 mm or more. The lower limit of the shaft diameter of the shaft member 1 may be 280 mm or 360 mm. If the shaft diameter of the shaft member 1 is equal to or greater than the lower limit and a coating layer is provided on the outer peripheral surface 11 of the shaft member 1, there is a high risk that the coating layer will be damaged and impurities will be generated. In contrast, the bearing device does not require a coating layer to be provided on the outer peripheral surface 11, and therefore can suppress the intrusion of impurities in the sliding area.

[0049] Although there is no particular limitation on the upper limit of the shaft diameter of the shaft member 1, it is preferably 1500 mm, and more preferably 1300 mm, for example. If the shaft diameter of the shaft member 1 exceeds the upper limit, the bearing device may become too large, which may go against the demand for miniaturization of the device.

[0050] The outer peripheral surface 11 of the shaft member 1 may have multiple roughness peaks calculated by the following procedure. First, based on a roughness curve with a measurement length of 4.0 mm measured in accordance with JIS-B0601(2013) with a cutoff value of 0.25 mm, the mean line of the roughness curve is set in accordance with JIS-B0601(2013). Using this mean line as a reference, the height of measurement points located above this mean line is defined as a positive value, and the height of measurement points located below this mean line is defined as a negative value. The average height of all measurement points with positive heights is defined as Thr0. Next, of the measurement points on the roughness curve, those that are higher than the adjacent measurement points on both sides and have a height greater than -Thr0 are defined as tentative peaks. Of the measurement points located between adjacent tentative peaks, the measurement point with the smallest height (the deepest from the adjacent tentative peaks) is defined as a valley. Then, for all tentative vertices, the height difference between the tentative vertex and the valleys adjacent to the tentative vertex on both sides is calculated, and vertices for which the larger height difference is less than 0.2 × Thr0 are excluded. As a result, the remaining tentative vertices are determined as roughness protrusion vertices.

[0051] When the roughness projection apex 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 projection on the outer peripheral surface 11 may be 55 μm or 58 μm. For a large-diameter shaft member 1, such as one whose shaft diameter is equal to or greater than the lower limit, the dimensional accuracy achieved by machining is likely to be insufficient, and it may be desirable to manually polish the outer peripheral surface 11. Manually polishing the outer peripheral surface 11 tends to increase the radius of curvature β of the roughness projection. If the radius of curvature β of the roughness projection is large, seizure is more likely to occur in the sliding area between the shaft member 1 and the bearing member 2. Even with this configuration, the bearing device can easily suppress seizure in the sliding area.

[0052] The "radius of curvature of a roughness protrusion" refers to a value calculated using the following procedure. First, a straight line is drawn from all measurement points located between the apex of the roughness protrusion and the valleys adjacent to the apex on both sides of the apex of the roughness protrusion toward the apex of the roughness protrusion, and the measurement point at which the gradient of the line is greatest is determined to be the end of the roughness protrusion. The roughness curve between the two ends of each roughness protrusion is approximated by the least squares method, and the quadratic coefficient of the quadratic function obtained is defined as a, and the radius of curvature of each roughness protrusion is calculated by -0.5 / a. The median value of the radii of curvature of all roughness protrusions on the roughness curve is determined to be the radius of curvature of the roughness protrusion.

[0053] The arithmetic mean roughness Ra1 of the outer peripheral surface 11 of the shaft member 1 is 0.05 μm or more and 0.30 μm or less, and the peak height Rpk1 of the outer peripheral surface 11 is 0.04 μm or more and 0.34 μm or less. As described above, when the outer peripheral surface 11 of the shaft member 1 is manually polished, the radius of curvature β of the roughness projections tends to increase. In this case, by polishing using sandpaper with a sufficiently large grit size, the arithmetic mean roughness Ra1 and the peak height Rpk1 can be reduced to within the above ranges. For example, by polishing using sandpaper with a grit size of 200 or more, the arithmetic mean roughness Ra1 and the peak height Rpk1 can be reduced to within the above ranges. The grit size of the sandpaper may be 500 or more, or may be 600 or more. The arithmetic mean roughness Ra1 of the outer peripheral surface 11 of the shaft member 1 and the height Rpk1 of the protruding peaks of this outer peripheral surface 11 can be set to the values ​​before the shaft member 1 and the bearing member 2 slide against each other.

[0054] The upper limit of the arithmetic mean roughness Ra1 of the outer peripheral surface 11 is preferably 0.16 μm, more preferably 0.12 μm, and even more preferably 0.08 μm. If the arithmetic mean roughness Ra1 of the outer peripheral surface 11 exceeds the upper limit, it may become difficult to suppress frictional resistance and seizure between the shaft member 1 and the bearing member 2.

[0055] The upper limit of the height Rpk1 of the protruding ridges on the outer peripheral surface 11 is preferably 0.22 μm, more preferably 0.18 μm, and even more preferably 0.14 μm. If the height Rpk1 of the protruding ridges on the outer peripheral surface 11 exceeds the upper limit, it may become difficult to suppress the frictional resistance and seizure between the shaft member 1 and the bearing member 2.

[0056] <Bearing materials> Examples of the bearing member 2 include crank bearings, intermediate bearings, and propulsion bearings for ships. Examples of the material of the bearing member 2 include white metal, kelmet, and aluminum alloy.

[0057] The inner peripheral surface 21 of the bearing member 2 surrounds the outer peripheral surface 11 of the shaft member 1 in the circumferential direction. The central axis of the inner peripheral surface 21 extends horizontally (the Y direction in FIG. 1). Lubricating oil 3 is supplied to the gap between the outer peripheral surface 11 and the inner peripheral surface 21, and an oil film 31 is formed by this lubricating oil 3. In this way, the bearing member 2 slidably supports the shaft member 1 by arranging its inner peripheral surface 21 opposite the outer peripheral surface 11 with the oil film 31 interposed therebetween.

[0058] The inner circumferential surface 21 receives a load from the outer circumferential surface 11 via the oil film 31. Therefore, the inner circumferential surface 21 has a region (load distribution) that receives the load. The load distribution extends in the direction of the central axis of the inner circumferential surface 21, and is formed in an arc shape on a cross section perpendicular to the central axis of the inner circumferential surface 21. Furthermore, the range of the load distribution can vary due to the rotation and vibration of the shaft member 1.

[0059] It is preferable that no coating layer, such as a lubricating film, is formed on the inner peripheral surface 21 of the bearing member 2. By not providing a coating layer on the inner peripheral surface 21 in this way, it is possible to suppress the intrusion of impurities into the sliding area between the shaft member 1 and the bearing member 2 and an increase in costs.

[0060] The hardness H1 [HV] of the shaft member 1 is preferably greater than the hardness H2 [HV] of the bearing member 2. Generally, the hardness H2 of the bearing member 2 is low, making it difficult to intentionally control the surface roughness of the inner peripheral surface 21 by machining or the like. Even in such cases, 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 polished due to 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, making it easier to suppress frictional resistance and seizure between the outer peripheral surface 11 and the inner peripheral surface 21. 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, even more preferably 6.0, and particularly preferably 8.0. If the ratio is less than the lower limit, it may be difficult to reduce the surface roughness of the inner peripheral surface 21 by rotation of the shaft member 1. Conversely, the upper limit of the ratio is not particularly limited, but can be set to, for example, 20, from the viewpoint of facilitating the selection of materials for the shaft member 1 and the bearing member 2.

[0061] The lower limit of the ratio (Ra2 / Ra1) of the arithmetic mean roughness Ra2 [μm] of the inner peripheral surface 21 of the bearing member 2 to the arithmetic mean roughness Ra1 [μm] of the outer peripheral surface 11 of the shaft member 1 is not particularly limited, but can be, for example, 0.26. On the other hand, the upper limit of this ratio is preferably 38.0, more preferably 37.1, even more preferably 22.6, and even more preferably 20.4. If the ratio exceeds this upper limit, it may become difficult to suppress frictional resistance and seizure between the outer peripheral surface 11 and the inner peripheral surface 21. Note that this ratio may be the ratio before the shaft member 1 and the bearing member 2 begin to slide against each other.

[0062] The lower limit of the ratio (Rpk2 / Rpk1) of the peak height Rpk2 [μm] of the inner peripheral surface 21 of the bearing member 2 to the peak height Rpk1 [μm] of the outer peripheral surface 11 of the shaft member 1 is not particularly limited, but can be, for example, 0.32. On the other hand, the upper limit of this ratio is preferably 69.0, more preferably 68.3, even more preferably 57.3, and even more preferably 27.4. If the ratio exceeds this upper limit, it may be difficult to suppress frictional resistance and seizure between the outer peripheral surface 11 and the inner peripheral surface 21. Note that this ratio may be the ratio before the shaft member 1 and the bearing member 2 begin to slide.

[0063] <Lubricating oil> Examples of the lubricating oil 3 include paraffin-based base oil. The lubricating oil 3 forms an oil film 31, thereby making it easy to maintain a fluid lubrication state between the outer circumferential surface 11 and the inner circumferential surface 21.

[0064] The oil film thickness h [μm] calculated by the following formula 1 is the limit oil film thickness h calculated by the following formula 2. lim [μm] or more is preferable.

[0065]

number

[0066] In the above formula 1, R means the equivalent radius [m] of the shaft member 1 and the bearing member 2, α means the viscosity pressure coefficient [1 / GPa] of the lubricating oil 3, η means the viscosity [Pa·sec] of the lubricating oil 3, u means the peripheral speed [m / sec] of the shaft member 1, E means the equivalent longitudinal elastic modulus [GPa] of the shaft member 1 and the bearing member 2, and w means the load [N / m] applied to the bearing member 2 per unit length in the axial direction of the shaft member 1. Also, in the above formula 2, Λ lim means the minimum oil film parameter value at which the oil film 31 maintains a fluid lubrication state. In the above formula 1, the circumferential speed u can be, for example, the average value of the rotation speed while the shaft member 1 is continuously rotating. In the above formula 1, the viscosity η can be, for example, the maximum temperature of the lubricating oil 3 while the shaft member 1 is continuously rotating. hIn this case, the η(T h ) can be used. In the above formula 1, the load per unit length w can be calculated by assuming that the total load of the shaft member 1 is directly applied to the inner peripheral surface 21, from the viewpoint of facilitating the calculation of the oil film thickness h. According to this assumption, the load per unit length w can be calculated by dividing the total load of the shaft member 1 by the width of the inner peripheral surface 21 (the length of the inner peripheral surface 21 in the central axial direction). In the above formula 1, the minimum oil film parameter value Λ lim can be set to 3 or more and 4 or less depending on the material properties of the shaft member 1 and the bearing member 2. In particular, when the surface roughness of the outer peripheral surface 11 of the shaft member 1 and the inner peripheral surface 21 of the bearing member 2 can be considered to follow a normal distribution, the minimum oil film parameter value Λ lim can be expressed as 3. In the above formula 2, 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 can be values ​​before the shaft member 1 and the bearing member 2 slide against each other.

[0067] In this way, the oil film thickness h is equal to the limit oil film thickness h lim As a result, the oil film 31 can easily suppress solid contact between the outer peripheral surface 11 and the inner peripheral surface 21. This makes it easy to maintain a fluid lubrication state between the outer peripheral surface 11 and the inner peripheral surface 21.

[0068] Limiting viscosity η of lubricating oil 3 lim [Pa·sec] can be calculated using the above formula 2 to transform the above formula 1 into the following formula 3.

[0069]

number

[0070] The viscosity η [Pa·sec] of lubricating oil 3 is the limit viscosity η lim In other words, the lower limit of the viscosity η [Pa·sec] of the lubricating oil 3 is 0.08 × η lim is preferable, and 0.19×η lim More than 0.37×η is more preferable. lim is more preferable, and 0.47×ηlim Furthermore, the lower limit of the viscosity η is the critical viscosity η lim On the other hand, the upper limit of the viscosity η may be 5.20×η lim Less than 3.70×η is preferable. lim is more preferable, and 1.43×η lim If the viscosity η is less than the lower limit, it may be difficult to maintain a fluid lubrication state between the outer peripheral surface 11 and the inner peripheral surface 21. Conversely, if the viscosity η exceeds the upper limit, the viscosity η may become too large, making it difficult to reduce the frictional resistance between the outer peripheral surface 11 and the inner peripheral surface 21.

[0071] Critical peripheral speed u of shaft member 1 lim [m / sec] can be calculated using the following formula 4 by transforming the above formula 1 using the above formula 2.

[0072]

number

[0073] The peripheral speed u [m / sec] of the shaft member 1 is the critical peripheral speed u lim That is, the lower limit of the peripheral speed u [m / sec] of the shaft member 1 is preferably 0.29 × u lim is preferable, and 0.53 × u lim is more preferable, and u lim On the other hand, the upper limit of the peripheral speed u is not particularly limited, but is, for example, 4.94×u lim If the peripheral speed u is less than the lower limit, it may be difficult to maintain a fluid lubrication state between the outer peripheral surface 11 and the inner peripheral surface 21.

[0074] Limit equivalent radius R of shaft member 1 and bearing member 2 lim [m] can be calculated by the following formula 5 by transforming the above formula 1 using the above formula 2.

[0075]

number

[0076] The equivalent radius R [m] of the shaft member 1 and the bearing member 2 is the limit equivalent radius R lim In other words, the lower limit of the equivalent radius R [m] is 0.08 × R lim is preferable, and 0.27 × R lim is more preferred, and R lim On the other hand, the upper limit of the equivalent radius R is not particularly limited, but in view of the demand for miniaturization of the device, it is more preferable to set the upper limit to, for example, 25.65×R lim If the equivalent radius R is less than the lower limit, it may be difficult to maintain a fluid lubrication state between the outer peripheral surface 11 and the inner peripheral surface 21.

[0077] <Advantages> In this bearing device, the arithmetic mean roughness Ra1 and protruding peak height Rpk1 of the outer peripheral surface 11 of the shaft member 1 are optimized, which makes it easy to maintain a fluid lubrication state between the outer peripheral surface 11 and the inner peripheral surface 21. Furthermore, this bearing device does not require the provision of a surface treatment layer such as a coating layer on the outer peripheral surface 11 and the inner peripheral surface 21. Therefore, this bearing device can suppress frictional resistance and seizure between the outer peripheral surface 11 and the inner peripheral surface 21 while suppressing the intrusion of impurities between the outer peripheral surface 11 and the inner peripheral surface 21 and increasing costs.

[0078] [Bearing device driving method] The method for driving the bearing device of FIG. 2 includes a driving step S1 for rotating the shaft member 1 using the bearing device of FIG.

[0079] <Drive process> In the driving step S1, the shaft member 1 is rotated while lubricating oil 3 is supplied into the gap between the shaft member 1 and the bearing member 2. One method for supplying the lubricating oil 3 is to provide a supply port for supplying the lubricating oil 3 on the inner peripheral surface 21 of the bearing member 2, and supply the lubricating oil 3 from this supply port so that the lubricating oil 3 circulates in the sliding area between the shaft member 1 and the bearing member 2. The lubricating oil 3 may be dripped between the outer peripheral surface 11 and the inner peripheral surface 21 before the shaft member 1 is rotated.

[0080] In the driving process S1, the oil film thickness h [μm] calculated by the following formula 1 is calculated by the limit oil film thickness h lim It is preferable to rotate the shaft member 1 so that the thickness becomes [μm] or more.

[0081]

number

[0082] In this way, the oil film thickness h is set to the limit oil film thickness h lim By controlling as described above, the oil film 31 can easily suppress solid contact between the outer peripheral surface 11 and the inner peripheral surface 21 .

[0083] The viscosity η of the lubricating oil 3 in the driving step S1 is the above-mentioned limit viscosity η lim In other words, the lower limit of the viscosity η [Pa·sec] is 0.08 × η lim is preferable, and 0.19×η lim More than 0.37×η is more preferable. lim is more preferable, and 0.47×η lim Furthermore, the lower limit of the viscosity η is the critical viscosity η lim On the other hand, the upper limit of the viscosity η may be 5.20×η lim Less than 3.70×η is preferable. lim is more preferable, and 1.43×η lim is more preferable. If the viscosity η is less than the lower limit, it may be difficult to maintain a fluid lubrication state between the outer peripheral surface 11 and the inner peripheral surface 21. Conversely, if the viscosity η exceeds the upper limit, the viscosity η becomes too large, which may make it difficult to reduce the friction resistance between the outer peripheral surface 11 and the inner peripheral surface 21. Note that the viscosity η here means the viscosity η while the shaft member 1 is being driven, and is referred to as the "critical viscosity η" lim The term "control based on the limit viscosity η of the lubricating oil 3 during the driving process S1" means that the viscosity η of the lubricating oil 3 during the driving process S1 is controlled based on the limit viscosity η immediately before the start of the driving process S1 by adjusting the driving conditions such as the peripheral speed u of the shaft member 1 and selecting the lubricating oil 3. lim This means that control is based on

[0084] In the driving step S1, the peripheral speed u of the shaft member 1 is set to the critical peripheral speed u lim That is, the lower limit of the circumferential velocity u [m / sec] of the shaft member 1 in the driving step S1 is preferably set to 0.29×u lim is preferable, and 0.53 × u lim is more preferable, and u lim On the other hand, the upper limit of the peripheral speed u is not particularly limited, but is, for example, 4.94×u lim If the peripheral speed u is less than the lower limit, it may be difficult to maintain a fluid lubrication state between the outer peripheral surface 11 and the inner peripheral surface 21.

[0085] <Advantages> By using the bearing device, the driving method of the bearing device makes it easy to maintain a fluid lubrication state between the outer peripheral surface 11 and the inner peripheral surface 21 in the driving step S1. Therefore, the driving method of the bearing device can suppress frictional resistance and seizure between the outer peripheral surface 11 and the inner peripheral surface 21 while suppressing the intrusion of impurities between the outer peripheral surface 11 and the inner peripheral surface 21 and an increase in costs.

[0086] [Other embodiments] The above-described embodiments do not limit the configuration of the present invention. Therefore, the above-described embodiments may include omissions, substitutions, or additions of components based on the description in this specification and common general technical knowledge, and all of these should be construed as falling within the scope of the present invention.

[0087] In the above embodiment, the central axis of the shaft member extends in the horizontal direction, but the central axis of this shaft member may be inclined relative to the horizontal direction. [Example]

[0088] The present invention will be described in detail below based on examples, but the present invention should not be construed as being limited by the descriptions in these examples.

[0089] In this example, a polishing test was conducted in which the outer peripheral surface of the shaft member was manually polished, and a sliding test was conducted in which the shaft member was rotated.

[0090] [Polishing test] In the polishing test, the outer surface of the shaft member was polished using sandpaper. The material of the shaft member was steel equivalent to S45C as specified in JIS-G4051 (2016). The outer diameter of the shaft member at the polished portion was 600 mm. Polishing was performed repeatedly using sandpaper with gradually increasing grit sizes. For each grit size, the arithmetic mean roughness (Ra1) and peak height (Rpk1) of the polished outer surface were measured using a Mitutoyo Corporation compact surface roughness tester ("SJ-310"). Four circumferential positions were determined at 90° intervals along the circumferential direction of the outer surface, and the arithmetic mean roughness (Ra1) and peak height (Rpk1) of the outer surface were measured at two different axial positions for each circumferential position. The evaluation length of each measurement position was 4 mm. The measurement conditions for the arithmetic mean roughness Ra1 were a measuring force of 0.75 mN, a probe radius of 2 μm, a high cutoff value (λc) of 0.8 mm, and a low cutoff value (λs) of 2.5 μm. Figure 3 shows the measurement results for arithmetic mean roughness Ra1, and Figure 4 shows the measurement results for protruding peak height Rpk1. Note that the plots in Figures 3 and 4 show the average values, and the error bars show the error range relative to the average values.

[0091] As shown in FIG. 3, when the sandpaper grit size is 150 or larger, the arithmetic mean roughness Ra1 is reduced to a range of 0.05 μm to 0.30 μm. Furthermore, when the sandpaper grit size is 200 or larger, the arithmetic mean roughness Ra1 converges to a range of 0.05 μm to 0.20 μm. On the other hand, as shown in FIG. 4, when the sandpaper grit size is 150 or larger, the protruding peak height Rpk1 of the outer surface of the shaft member is reduced to a range of 0.04 μm to 0.34 μm. Furthermore, when the sandpaper grit size is 200 or larger, the protruding peak height Rpk1 of the outer surface of the shaft member converges to a range of 0.04 μm to 0.26 μm. In other words, in the manufacture of a shaft member involving manual polishing, if the arithmetic mean roughness Ra1 and protruding peak height Rpk1 of the outer surface of the shaft member are within the above ranges, the surface roughness of the shaft member is considered to be reduced to near its limit. For this reason, it is believed that by having the arithmetic mean roughness Ra1 and the peak height Rpk1 of the outer peripheral surface of the shaft member fall within the above ranges, frictional resistance and seizure between the shaft member and the bearing member can be suppressed.

[0092] [Sliding test] In the sliding tests, shaft members were rotated under the conditions shown below in No. 1 to No. 106 using Apparatus A (a friction and wear tester manufactured by Chihoda Seiko Co., Ltd.), Apparatus B (a bearing life tester manufactured by Chihoda Seiko Co., Ltd.), and Apparatus C (a friction and wear tester manufactured by Shinko Engineering Co., Ltd.). The shaft members used had their outer surfaces manually polished. In Apparatus A, the shaft members were rotated while pressing the inner surface of a bearing member surrounding the outer surface of the shaft member within a range of approximately 90° against the shaft member with a constant load for Nos. 29 to 38, and a flat bearing member against the shaft member with a constant load for Nos. 13 to 26 and Nos. 39 to 106. In Apparatus B and Apparatus C, the shaft members were rotated while pressing the inner surface of a bearing member surrounding the entire outer surface of the shaft member with a constant load against the shaft member. In addition, for each of No. 1 to No. 106, the hardness of the shaft member and the shaft member, as well as the arithmetic mean roughness and protruding peak height of the shaft member and the shaft member before and after the sliding test were measured. Tables 1 to 5 show the measurement results for No. 1 to No. 106. However, in Tables 1 to 5, Ra 1Ameans the arithmetic mean roughness of the shaft member before the sliding test, and Ra 1B means the arithmetic mean roughness of the shaft member after the sliding test, and Ra 2A means the arithmetic mean roughness of the bearing material before the sliding test, and Ra 2B means the arithmetic mean roughness of the bearing material after the sliding test. In addition, in Tables 1 to 5, Rpk 1A means the height of the protruding part of the shaft before the sliding test, and Rpk 1B means the height of the protruding part of the shaft member after the sliding test, and Rpk 2A means the height of the protruding peak of the bearing member before the sliding test, and Rpk 2B indicates the height of the protruding peak of the bearing member after the sliding test. The "hardness ratio," "arithmetic mean roughness ratio," and "protruding peak height ratio" shown in Tables 1 to 5 are values ​​calculated to four significant digits. In the sliding test, the hardness was measured using a Vickers hardness tester ("FV-310") manufactured by Futuretec Corporation for shaft members No. 1 to No. 28 and bearing members No. 13 to No. 26, a Vickers hardness tester ("MVK-E") manufactured by Akashi Seisakusho Co., Ltd. for bearing members No. 1 to No. 12 and No. 27 to No. 28, and a Vickers hardness tester ("AVK") manufactured by Akashi Seisakusho Co., Ltd. for shaft members No. 29 to No. 106 and bearing members. The arithmetic mean roughness and peak height were measured using a small surface roughness tester ("SJ-310") manufactured by Mitutoyo Corporation for shaft members and bearing members No. 1 to No. 28, and a small surface roughness tester ("SJ-210") manufactured by Mitutoyo Corporation for shaft members and bearing members No. 29 to No. 106. In measuring the arithmetic mean roughness and peak height, the evaluation length was 4 mm for No. 1 to No. 28, and 12.5 mm for No. 29 to No. 106. The measurement conditions for the arithmetic mean roughness were as follows: for No. 1 to No. 28, a measuring force of 0.75 mN, a probe radius of 2 μm, a high-pass cutoff value (λc) of 0.8 mm, and a low-pass cutoff value (λs) of 2.5 μm; for No. 29 to No. 106, a measuring force of 4 mN, a probe radius of 5 μm, a high-pass cutoff value (λc) of 2.5 mm, and a low-pass cutoff value (λs) of 8 μm.

[0093] (No.1 to No.3) For No. 1 to No. 3, the load from the bearing member to the shaft member was 10 kN. The initial rotation speed of the shaft member was 3000 rpm, and it was gradually reduced by 250 rpm at 10-minute intervals to a minimum of 250 rpm. Manganese steel was used for the shaft member, and WJ1 white metal as specified in JIS-H5401 (1958) was used for the bearing member. ENEOS Corporation's "FBK Oil RO32" was used as the lubricant. The lubricant, initially at 70°C, was supplied to the sliding area between the outer surface of the shaft member and the inner surface of the bearing member, and the lubricant was circulated while immersing the sliding area in the lubricant.

[0094] (No.4 to No.12) For No. 4 to No. 12, the rotation speed of the shaft member was kept constant at 3,500 rpm. The load from the bearing member to the shaft member was initially 0 kN and was increased in stages of 0.5 kN at 5-minute intervals up to a maximum of 20 kN. Manganese steel was used for the shaft member, and white metal equivalent to WJ1 specified in JIS-H5401 (1958) was used for the bearing member. ENEOS Corporation's "FBK Oil RO32" was used as the lubricant. The lubricant, initially at 70°C, was supplied to the sliding area between the outer surface of the shaft member and the inner surface of the bearing member, and was allowed to circulate within this sliding area.

[0095] (No.13 to No.17) For Nos. 13 to 17, the shaft member rotation speed was 400 rpm for No. 13, 200 rpm for No. 14, 100 rpm for No. 15, 50 rpm for No. 16, and 800 rpm for No. 17. The load from the bearing member to the shaft member was initially 0 kN and gradually increased to 1 kN in 0.1 kN increments at 1-minute intervals. The shaft member was made of S45C steel as specified in JIS-G4051 (2016), and the bearing member was made of WJ2 white metal as specified in JIS-H5401 (1958). The lubricant used was "FBK Oil RO32" manufactured by ENEOS Corporation. The lubricant was supplied at room temperature to the sliding area between the outer surface of the shaft member and the inner surface of the bearing member and circulated through this sliding area.

[0096] (No. 18 and No. 25) For Nos. 18 and 25, the shaft member was rotated for 240 minutes at a constant rotation speed of 50 rpm and a constant load of 1 kN from the bearing member to the shaft member. For Nos. 18 and 25, the same shaft members and bearing members as Nos. 13 to 17 were used, except for the hardness and surface roughness. The same lubricating oil was used as for Nos. 13 to 17, and the same lubricating oil was circulated as for Nos. 13 to 17.

[0097] (No. 19 and No. 26) For Nos. 19 and 26, the shaft member was rotated for 240 minutes at a constant rotation speed of 100 rpm and a constant load of 1 kN from the bearing member to the shaft member. For Nos. 19 and 26, the same shaft members and bearing members as those for Nos. 13 to 17 were used, except for the hardness and surface roughness. The same lubricating oil was used as for Nos. 13 to 17. The lubricating oil was applied once at room temperature to the sliding area between the outer circumferential surface of the shaft member and the inner circumferential surface of the bearing member at the start of the sliding test.

[0098] (No. 20 to No. 24) For Nos. 20 to 24, the rotation speed of the shaft member was 400 rpm for No. 20, 200 rpm for No. 21, 100 rpm for No. 22, 50 rpm for No. 23, and 800 rpm for No. 24. Other than the rotation speed of the shaft member, Nos. 20 to 24 were driven under the same conditions as Nos. 13 to 17. Other than the hardness and surface roughness, Nos. 20 to 24 used the same shaft members and bearing members as Nos. 13 to 17. The same lubricating oil was used as for Nos. 13 to 17, and circulated in the same manner as for Nos. 13 to 17.

[0099] (No. 27 and No. 28) In Nos. 27 and 28, the driving conditions were the same as in Nos. 1 to 3, except that the rotation speed of the shaft member was reduced every minute. In Nos. 27 and 28, nickel-chromium-molybdenum alloy steel was used as the shaft member, and the same bearing members as in Nos. 1 to 3 were used except for the hardness and surface roughness. The same lubricating oil as in Nos. 1 to 3 was used and circulated in the same way as in Nos. 1 to 3.

[0100] (No. 29 to No. 38) For Nos. 29 to 38, the shaft rotation speed was 200 rpm for No. 29, 800 rpm for No. 30, 100 rpm for No. 31, 200 rpm for No. 32, 800 rpm for No. 33, 200 rpm for No. 34, 800 rpm for No. 35, 100 rpm for No. 36, 200 rpm for No. 37, and 800 rpm for No. 38. The load from the bearing member to the shaft member was initially 0 kN and was increased in steps of 0.1 kN to 1 kN at 1-minute intervals. The shaft member was made of S45C steel as specified in JIS-G4051 (2016), and the bearing member was made of WJ2 white metal as specified in JIS-H5401 (1958). The lubricating oil used was "FBK Oil RO100" manufactured by ENEOS Corporation for Nos. 29, 30, 34, and 35, and "FBK Oil RO32" manufactured by ENEOS Corporation for Nos. 31 to 33 and Nos. 36 to 38. The lubricating oil was applied once at room temperature to the sliding area between the outer circumferential surface of the shaft member and the inner circumferential surface of the bearing member at the start of the sliding test.

[0101] For Nos. 29 to 38, the temperature [°C] was measured using a thermocouple attached 2 mm deep from the surface of the bearing member, and this temperature was calculated as the temperature of the lubricating oil. For Nos. 29 to 38, the friction force during rotation of the shaft member was measured using a load cell attached to the holder holding the bearing member, and the friction coefficient μ was calculated by dividing the friction force by the applied load. These measured values ​​were used to evaluate the fluid lubrication state and calculate the oil film thickness, as described below.

[0102] (No.39 to No.42) For Nos. 39 to 42, the shaft member rotation speed was maintained at 100 rpm, and the load from the bearing member to the shaft member was maintained at 1 kN. The shaft member was rotated for a maximum of 900 minutes. Due to equipment limitations, the test was discontinued if the friction force measured by the load cell attached to the holder holding the bearing member exceeded approximately 294 kN, or if the temperature measured by a thermocouple attached 2 mm below the surface of the bearing member exceeded 100°C. The shaft member was made of S45C steel as specified in JIS-G4051 (2016), and the bearing member was made of WJ2 white metal as specified in JIS-H5401 (1958). ENEOS Corporation's "FBK Oil RO32" was used as the lubricant. Lubricant was applied only once at 20°C to the sliding area between the outer surface of the shaft member and the inner surface of the bearing member at the start of the sliding test.

[0103] (No.43 to No.45) For Nos. 43 to 45, the shaft member rotation speed was 200 rpm for No. 43 and 100 rpm for Nos. 44 and 45. The load from the bearing member to the shaft member was maintained constant at 1 kN, and the shaft member was rotated for a maximum of 320 minutes. Due to equipment limitations, the test was discontinued if the friction force measured by the load cell attached to the holder holding the bearing member exceeded approximately 294 kN, or if the temperature measured by a thermocouple attached 2 mm below the surface of the bearing member exceeded 100°C. For Nos. 43 to 45, the shaft members and bearing members were identical to those used for Nos. 39 to 42, except for hardness and surface roughness. The lubricant used was the same as for Nos. 39 to 42. In No. 43, the lubricating oil was dropped once at 20°C onto the sliding area between the outer circumferential surface of the shaft member and the inner circumferential surface of the bearing member at the start of the sliding test. In Nos. 44 and 45, the lubricating oil was supplied to the sliding area at 20°C and circulated while the sliding area was immersed in the lubricating oil.

[0104] (No. 46 to No. 84) For Nos. 46 to 84, the rotation time of the shaft members was set as follows: 1 minute for Nos. 46 and 65, 5 minutes for Nos. 47 and 66, 10 minutes for Nos. 48 and 67, 20 minutes for Nos. 49 and 68, 30 minutes for Nos. 50 and 69, 40 minutes for Nos. 51 and 70, 50 minutes for Nos. 52 and 71, 60 minutes for Nos. 53 and 72, 90 minutes for Nos. 54 and 73, and 1 minute for Nos. 55 and 74. The test times were 20 minutes for No. 56, 151 minutes for No. 56, 150 minutes for No. 75, 180 minutes for No. 57 and No. 76, 240 minutes for No. 58 and No. 77, 360 minutes for No. 59 and No. 78, 480 minutes for No. 60 and No. 79, 600 minutes for No. 61 and No. 80, 720 minutes for No. 81, 840 minutes for No. 62 and No. 82, 1080 minutes for No. 63 and No. 83, and 1440 minutes for No. 64 and No. 84. Other operating conditions for No. 46 to No. 84 were the same as for No. 39 to No. 42. For No. 46 to No. 84, the same shaft and bearing components as No. 39 to No. 42 were used, except for hardness and surface roughness. Furthermore, the lubricant used for Nos. 46 to 64 was "FBK Oil RO32" manufactured by ENEOS Corporation, and for Nos. 65 to 84 was "FBK Oil RO100" manufactured by ENEOS Corporation. As with Nos. 39 to 42, this was only added dropwise at 20°C at the start of the sliding test.

[0105] (No.85 to No.91) For Nos. 85 to 91, the shaft member rotation speed was 100 rpm for No. 85, 200 rpm for No. 86, 800 rpm for No. 87, 800 rpm for No. 88, 100 rpm for No. 89, 200 rpm for No. 90, and 800 rpm for No. 91. The load from the bearing member to the shaft member was initially 0 kN and gradually increased in 0.1 kN increments to 1 kN at 1-minute intervals. The shaft member was made of S45C steel as specified in JIS-G4051 (2016), and the bearing member was made of an Al-Sn-Cu alloy (hereinafter referred to as aluminum alloy) with a Sn content of 7.0 mass% and a Cu content of 2.5 mass%. The lubricant used was "FBK Oil RO100" manufactured by ENEOS Corporation. The lubricating oil was dropped only once onto the sliding area between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member at room temperature at the start of the sliding test.

[0106] For Nos. 85 to 91, the lubricating oil temperature and friction coefficient μ were determined in the same manner as for Nos. 29 to 38. These measured values ​​were used to evaluate the hydrodynamic lubrication state and calculate the oil film thickness, which will be described later.

[0107] (No.92 to No.106) For Nos. 92 to 106, the shaft member rotation speed was kept constant at 800 rpm, and the load from the bearing member to the shaft member was kept constant at 0.3 kN. The shaft member rotation time was 1 minute for Nos. 92 and 100, 5 minutes for Nos. 93 and 101, 10 minutes for Nos. 94 and 102, 20 minutes for Nos. 95 and 103, 30 minutes for Nos. 96 and 104, 40 minutes for Nos. 97 and 105, 50 minutes for Nos. 98 and 106, and 60 minutes for No. 99. For Nos. 92 to 106, the shaft members and bearing members were the same as those for Nos. 85 to 91, except for the hardness and surface roughness. The lubricant used was "FBK Oil RO32" manufactured by ENEOS Corporation, which was applied once at 20°C at the start of the sliding test, as with Nos. 39 to 42.

[0108] [Table 1]

[0109] [Table 2]

[0110] [Table 3]

[0111] [Table 4]

[0112] [Table 5]

[0113] (burn-in) Under conditions No. 1 to No. 106, no transfer from the shaft member to the bearing member or from the bearing member to the shaft member that would interfere with the surface roughness measurement after the sliding test was observed. In other words, no adhesion was visually confirmed on the outer surface of the shaft member or the inner surface of the bearing member after the sliding test.

[0114] (hardness) For No. 1 to No. 106, the ratio of the hardness H1 of the shaft material to the hardness H2 of the bearing material (H1 / H2) is plotted on the horizontal axis, and the ratio of the arithmetic mean roughness Ra 1B / Ra 1A and Ra 2B / Ra 2A The graph in Fig. 5 shows the ratio of the protruding peak height Rpk for No. 1 to No. 12, No. 27, No. 28, and No. 39 to No. 106, with H1 / H2 as the horizontal axis. 1B / Rpk 1A The graph shows the ratio of the peak height Rpk for No. 1 to No. 28 and No. 39 to No. 106, with H1 / H2 as the horizontal axis. 2B / Rpk 2AThe graph with the vertical axis is shown in Figure 6. However, the H1 / H2 values ​​of No. 13 to No. 19 on the horizontal axis in Figures 5 and 6 represent the average value of the H1 / H2 values ​​of No. 13 to No. 19. In addition, the points in Figures 5 and 6 represent the average value, and the error bars represent the error range for the average value.

[0115] As shown in Figures 5 and 6, the arithmetic mean roughness and peak height of the outer peripheral surface of the shaft member did not change significantly before and after the sliding test. On the other hand, the arithmetic mean roughness Ra2 of the inner peripheral surface of the bearing member showed a tendency to decrease after the sliding test (Ra 2B / Ra 2A <1). In addition, when the hardness ratio H1 / H2 is 4.1 or more, the height of the protruding peak of the bearing member tends to decrease after the sliding test (Rpk 2B / Rpk 2A <1). This shows that by setting the hardness ratio H1 / H2 to 4.1 or more, the inner peripheral surface of the bearing member can be easily polished by sliding with the shaft member.

[0116] (arithmetic mean roughness ratio) From Tables 1 to 4, when white metal is used for the bearing member, the arithmetic mean roughness Ra of the inner peripheral surface of the bearing member before the sliding test 2A is 0.34 μm or more and 1.85 μm or less, and after the sliding test, the arithmetic mean roughness Ra of the inner circumferential surface of the bearing member 2B is 0.08 μm or more and 1.24 μm or less. Therefore, the arithmetic mean roughness Ra2 of the inner peripheral surface of the bearing member is considered to be in the range of 0.08 μm or more and 1.85 μm or less before and after the sliding test. On the other hand, as described above, if the surface roughness of the shaft member is reduced to near its limit, it is considered that the arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member can be controlled to 0.05 μm or more and 0.30 μm or less. Based on these factors, it is considered that the ratio of the arithmetic mean roughness Ra2 of the inner peripheral surface of the bearing member to the arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member (Ra2 / Ra1) can be controlled within a range with a lower limit of 0.27, obtained by dividing 0.08 by 0.30, and an upper limit of 37.0, obtained by dividing 1.85 by 0.05.

[0117] From Table 5, when an aluminum alloy is used for the bearing member, the arithmetic mean roughness Ra of the inner circumferential surface of the bearing member before the sliding test is 2A After the sliding test, the arithmetic mean roughness Ra of the inner surface of the bearing member 2B is 0.21 μm or more and 1.02 μm or less. Therefore, the arithmetic mean roughness Ra2 of the inner peripheral surface of the bearing member is considered to be in the range of 0.21 μm or more and 1.02 μm or less before and after the sliding test. On the other hand, as described above, if the surface roughness of the shaft member is reduced to near its limit, it is considered that the arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member can be controlled to 0.05 μm or more and 0.30 μm or less. Based on these factors, it is considered that the ratio of the arithmetic mean roughness Ra2 of the inner peripheral surface of the bearing member to the arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member (Ra2 / Ra1) can be controlled within a range with a lower limit of 0.70, obtained by dividing 0.21 by 0.30, and an upper limit of 20.4, obtained by dividing 1.02 by 0.05.

[0118] From the above, it is considered that the ratio (Ra2 / Ra1) of the arithmetic mean roughness Ra2 of the inner peripheral surface of the bearing member to the arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member can be controlled within the range of 0.27 to 37.0.

[0119] (Ratio of protruding peak height) From Tables 1 to 4, when white metal is used for the bearing member, the height of the protruding peaks on the inner circumferential surface of the bearing member, Rpk, before the sliding test 2A is 0.40 μm or more and 2.29 μm or less, and after the sliding test, the protruding peak height Rpk of the inner peripheral surface of the bearing member 2Bis 0.11 μm or more and 0.99 μm or less. Therefore, the protruding peak height Rpk2 of the inner peripheral surface of the bearing member is considered to be in the range of 0.11 μm or more and 2.29 μm or less before and after the sliding test. On the other hand, as described above, if the surface roughness of the shaft member is reduced to near its limit, the protruding peak height Rpk1 of the outer peripheral surface of the shaft member is considered to be controllable to 0.04 μm or more and 0.34 μm or less. Based on these factors, it is considered that the ratio of the protruding peak height Rpk2 of the inner peripheral surface of the bearing member to the protruding peak height Rpk1 of the outer peripheral surface of the shaft member (Rpk2 / Rpk1) can be controlled within a range with a lower limit of 0.32, obtained by dividing 0.11 by 0.34, and an upper limit of 57.3, obtained by dividing 2.29 by 0.04.

[0120] From Table 5, when an aluminum alloy is used for the bearing member, the height of the protruding peaks on the inner circumferential surface of the bearing member, Rpk, before the sliding test 2A is 0.98 μm or more and 1.66 μm or less, and after the sliding test, the protruding peak height Rpk of the inner peripheral surface of the bearing member 2B is 0.16 μm or more and 2.73 μm or less. Therefore, it is believed that the protruding peak height Rpk2 of the inner peripheral surface of the bearing member is in the range of 0.16 μm or more and 2.73 μm or less before and after the sliding test. On the other hand, as described above, if the surface roughness of the shaft member is reduced to near its limit, it is believed that the protruding peak height Rpk1 of the outer peripheral surface of the shaft member can be controlled to 0.04 μm or more and 0.34 μm or less. Based on these factors, it is believed that the ratio of the protruding peak height Rpk2 of the inner peripheral surface of the bearing member to the protruding peak height Rpk1 of the outer peripheral surface of the shaft member (Rpk2 / Rpk1) can be controlled within a range with a lower limit of 0.47, obtained by dividing 0.16 by 0.34, and an upper limit of 68.3, obtained by dividing 2.73 by 0.04.

[0121] From the above, it is considered that the ratio (Rpk2 / Rpk1) of the protruding ridge height Rpk2 on the inner peripheral surface of the bearing member to the protruding ridge height Rpk1 on the outer peripheral surface of the shaft member can be controlled within the range of 0.32 or more and 68.3 or less.

[0122] (Hydrodynamic lubrication) For Nos. 29 to 38 and Nos. 85 to 91, the horizontal axis represents the bearing characteristic number [m -1 ], and the vertical axis is the friction coefficient, and the values ​​for each load condition are plotted. The results are shown in Figures 7, 8, and 9. The bearing characteristic number is calculated by the formula: viscosity η [Pa·sec] × peripheral speed u [m / sec] / P (load [N] × 10 -6 The viscosity η was calculated using Equation 8, where ρ is the known density of the lubricating oil at 15°C.

[0123] As shown in Figures 7 and 8, inflection points are observed in the region where the bearing characteristic numbers are small for No. 31 and No. 32. In other words, when the bearing characteristic numbers are small for No. 31 and No. 32, it is believed that a transition from hydrodynamic lubrication to mixed lubrication occurs. On the other hand, No. 29, No. 30, No. 33 to No. 38 are believed to be in hydrodynamic lubrication.

[0124] As shown in Fig. 9, an inflection point is observed in No. 85, indicating a transition from hydrodynamic lubrication to mixed lubrication. On the other hand, No. 86 to No. 91 show low friction coefficients regardless of the bearing characteristics, indicating that they are in a hydrodynamic lubrication state.

[0125] (oil film thickness) For Nos. 29 to 38 and Nos. 85 to 91, the oil film thickness h [μm] was calculated using Equation 1 above. Here, the viscosity pressure coefficient α was found using Equation 12 above. Furthermore, u is the rotation speed of the shaft member converted into units of m / s, and w is found by dividing the load [N] applied to the shaft member due to the pressing of the bearing member by the width of the inner surface of the bearing member. The calculation results are shown in Table 6. Note that the oil film thickness h shown in Table 6 is the value when the above bearing characteristic numbers are at their minimum.

[0126] (Limit oil film thickness) For No. 29 to No. 38 and No. 85 to No. 91, the limit oil film thickness h before the sliding test limA [μm] and the limit oil film thickness h after the sliding test limB[μm] is the oil film parameter Λ lim The calculation was performed using the above formula 2, with 3 as the value. The calculation results are shown in Table 6.

[0127] (limiting viscosity) For No. 29 to No. 38 and No. 85 to No. 91, the limiting viscosity η before the sliding test limA The limit oil film thickness h limA Using the limiting viscosity η after the sliding test, limB The limit oil film thickness h limB These were calculated using the above-mentioned formula 3. The calculation results are shown in Table 6. The limit viscosity shown in Table 6 is the value when the number of bearing characteristics is at its minimum.

[0128] (ratio of viscosity to limiting viscosity) The viscosity η ratio to the limiting viscosity was determined for Nos. 29 to 38 and Nos. 85 to 91. The results are shown in Table 6. The viscosity η of lubricating oils Nos. 29 to 38 and Nos. 85 to 91 was determined as the product of the known kinematic viscosity of the lubricating oil at 40°C and the known density at 15°C, based on a lubricating oil temperature of 40°C. The "viscosity ratio to the limiting viscosity" shown in Table 6 is a value calculated to four significant digits.

[0129] [Table 6]

[0130] (Viscosity evaluation) As shown in Table 6, when white metal is used for the bearing material, the limit viscosity η limA The ratio of viscosity η to limA ) for 0.19<η / η limA No. 29, No. 30, No. 33 to No. 35, No. 37 and No. 38, which satisfy <5.20, are in a hydrodynamic lubrication state. On the other hand, η / η limA Nos. 31 and 32, which have a value of ≦0.19, are unable to maintain a fluid lubrication state. When an aluminum alloy is used for the bearing material, the limit viscosity ηlimA The ratio of viscosity η to limA ) for 0.08≦η / η limA No. 86 to No. 91, which satisfy the relation <5.20, are in a hydrodynamic lubrication state. On the other hand, η / η limA No. 85, which has a value of <0.08, is unable to maintain a fluid lubrication state. [Industrial Applicability]

[0131] A bearing device according to one aspect of the present invention can suppress frictional resistance and seizure between the shaft member and the bearing member while preventing the inclusion of impurities and increasing costs, and can therefore be applied to bearing devices for ships, for example. [Explanation of symbols]

[0132] 1 Shaft member 11 Outer surface 2 Bearing materials 21 Inner surface 3 Lubricating oil 31 Oil slick P center axis R1 Radius of outer surface R2 Radius of inner surface

Claims

1. a shaft member having a shaft diameter of 180 mm or more; a bearing member that slidably supports an outer peripheral surface of the shaft member; a lubricating oil supplied to the gap between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member, which forms an oil film in the gap; A bearing device comprising: The shaft member is a crankshaft, an intermediate shaft, or a propeller shaft for a ship, The arithmetic mean roughness Ra of the outer circumferential surface of the shaft member １ is 0.05 μm or more and 0.30 μm or less, and the height Rpk of the protruding peak portion of the outer peripheral surface １ The bearing device has a surface roughness of 0.04 μm or more and 0.34 μm or less.

2. The hardness of the shaft member is H １ [HV], the hardness of the bearing member is H ２ When [HV] is used, H １ / H ２ 2. The bearing device according to claim 1, wherein the ratio of the axial length of the bearing to the axial length of the shaft is 4.1 or more.

3. The arithmetic mean roughness of the inner peripheral surface of the bearing member is Ra ２ [μm], the height of the protruding ridge on the inner peripheral surface of the bearing member is Rpk ２ When [μm], Ra ２ / Ra １ is 0.26 or more and 38.0 or less, and Rpk ２ / Rpk １ 3. The bearing device according to claim 1, wherein the value of the saturation coefficient is 0.32 or more and 69.0 or less.

4. The oil film thickness h [μm] calculated by the following formula 1 is the limit oil film thickness h calculated by the following formula 2. ｌｉｍ The bearing device according to claim 1, 2 or 3, wherein the thickness is 1 μm or more. [Equation 1] In the above formula 1, R represents the equivalent radius [m] of the shaft member and the bearing member, α represents the viscosity pressure coefficient [1 / GPa] of the lubricating oil, η represents the viscosity of the lubricating oil [Pa·sec], u represents the peripheral speed [m / sec] of the shaft member, E represents the equivalent longitudinal elastic modulus [GPa] of the shaft member and the bearing member, and w represents the load [N / m] applied to the bearing member per unit length in the axial direction of the shaft member. In the above formula 2, Λ ｌｉｍ means the minimum oil film parameter value at which the oil film maintains a hydrodynamic lubrication state, and Ra ２ means the arithmetic mean roughness [μm] of the inner peripheral surface of the bearing member.

5. The viscosity η of the lubricating oil is calculated by the following formula 3: ｌｉｍ 5. The bearing device according to claim 4, wherein the viscosity is 100 Pa·sec or more. [Equation 2]

6. The peripheral speed u of the shaft member is the limit peripheral speed u of the shaft member calculated by the following formula 4: ｌｉｍ 5. The bearing device according to claim 4, wherein the rotational speed is 1000 kJ / s or more. [Equation 3]

7. The equivalent radius R of the shaft member and the bearing member is calculated by the following formula 5: ｌｉｍ 5. The bearing device according to claim 4, wherein the length is equal to or greater than [m]. [Equation 4]

8. 6. The bearing device according to claim 1, wherein the viscosity η of the lubricating oil satisfies the following formula 6: 0.08×η ｌｉｍ ≦η<5.20×η ｌｉｍ ・・・6 However, in the above formula 6, η ｌｉｍ is the equivalent radius of the shaft member and the bearing member, R [m] is the viscosity pressure coefficient of the lubricating oil, α [1 / GPa] is the viscosity of the lubricating oil, η [Pa·sec] is the viscosity of the lubricating oil, u [m / sec] is the peripheral speed of the shaft member, E [GPa] is the equivalent modulus of longitudinal elasticity of the shaft member and the bearing member, w [N / m] is the load applied to the bearing member per unit length in the axial direction of the shaft member, and Λ is the minimum oil film parameter value for maintaining the oil film in a fluid lubrication state. ｌｉｍ The arithmetic mean roughness of the inner peripheral surface of the bearing member is Ra ２ In this case, the limit viscosity [Pa·sec] of the lubricating oil is calculated by the following formula 3. [Equation 5]

9. A method for driving a bearing device, comprising: a driving step of rotating the shaft member using a bearing device including a shaft member having a shaft diameter of 180 mm or more, a bearing member that slidably supports the outer peripheral surface of the shaft member, and lubricating oil that 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; The shaft member is a crankshaft, an intermediate shaft, or a propeller shaft for a ship, The arithmetic mean roughness Ra of the outer circumferential surface of the shaft member １ is 0.05 μm or more and 0.30 μm or less, and the height Rpk of the protruding peak portion of the outer peripheral surface １ A method for driving a bearing device, wherein the surface roughness is 0.04 μm or more and 0.34 μm or less.

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