Bearing device and method of driving a bearing device

Abstract

Provided are a bearing device and a driving method for the bearing device. A bearing device includes: a shaft member having a shaft diameter of 180 mm or more; a bearing member that supports an outer circumferential surface of the shaft member so as to be slidable; and lubricating oil that is supplied to a gap between the outer circumferential surface of the shaft member and an inner circumferential surface of the bearing member and forms an oil film in the gap, wherein an arithmetic average roughness Ra1 of the outer circumferential surface of the shaft member is 0.05 μm or more and 0.30 μm or less, and a maximum height of surface asperities Rpk1 of the outer circumferential surface is 0.04 μm or more and 0.34 μm or less.

Description

Technical Field

[0001] The present invention relates to a bearing device and a driving method of the bearing device. Background Art

[0002] Marine bearing systems, for example, include shaft components such as crankshafts, intermediate shafts, and propeller shafts, and bearing components such as sliding bearings that slidably support these shaft components. Lubricating oil is supplied to the gaps between the shaft components and the bearing components. This lubricating oil forms an oil film between the shaft components and the bearing components, reducing frictional resistance between the two components.

[0003] When the oil film is adequately formed, the viscosity of the oil film primarily contributes to frictional resistance, thus maintaining a low frictional resistance. On the other hand, when the oil film is insufficiently formed, in addition to the viscosity of the oil film, the solid contact between the shaft and bearing components can also contribute to frictional resistance, thus increasing frictional resistance. Furthermore, when the oil film is insufficiently formed, seizures are more likely to occur between the shaft and bearing components.

[0004] As a technique for reducing frictional resistance and sintering of sliding components, for example, Patent Document 1 describes forming an amorphous carbon film containing nitrogen on the sliding surface. Furthermore, Patent Document 2 describes a composite sliding component having surface characteristics that can cope with friction reduction in internal combustion engines.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-025396

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2004-116707

[0009] However, if the coating described in Patent Document 1 is formed on the surface of a bearing component used in a ship, for example, under high load conditions, there is a risk that impurities may be mixed into the lubricating oil due to damage to the coating. Furthermore, if the coating is formed on the surface of a large ship bearing component, equipment investment and costs may increase. Meanwhile, the technology described in Patent Document 2 assumes reciprocating motion of the sliding component. Therefore, if this technology is applied to a bearing device that relies on the rotation of the shaft component, it may not be possible to suppress frictional resistance and seizure between the shaft component and the bearing component. Summary of the Invention

[0010] Problems to be solved by the invention

[0011] The present invention has been made based on the above circumstances, and an object of the present invention is to provide a bearing device that can suppress the incorporation of impurities and the increase in cost, and can suppress the frictional resistance and seizure between the shaft member and the bearing member.

[0012] Solutions to Problems

[0013] A bearing device of one embodiment of the present invention completed to solve the above-mentioned problem comprises: a shaft member having a shaft diameter of 180 mm or more; a bearing member supporting the outer peripheral surface of the shaft member so as to be slidable; 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 greater than 0.05 μm and less than 0.30 μm, and the height Rpk1 of the protruding peak of the outer peripheral surface is greater than 0.04 μm and less than 0.34 μm.

[0014] Effects of the Invention

[0015] A bearing device according to one aspect of the present invention can suppress the incorporation of impurities and an increase in cost, and can also suppress frictional resistance and seizure between a shaft member and a bearing member. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic cross-sectional view showing a cut surface perpendicular to the central axis of a shaft member in a bearing device according to one embodiment of the present invention.

[0017] Figure 2 This is a flowchart illustrating a method for driving a bearing device according to one embodiment of the present invention.

[0018] Figure 3 This is a graph showing the relationship between the grit number of sandpaper used to polish a shaft member and the arithmetic mean roughness of the shaft member.

[0019] Figure 4 This is a graph showing the relationship between the grit number of sandpaper used to polish a shaft member and the height of the protruding peak of the shaft member.

[0020] Figure 5 This 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 of the shaft member and the bearing member before and after the sliding test.

[0021] Figure 6 This is a graph showing the relationship between the hardness ratio of the shaft member to the bearing member and the ratio of the protruding peak heights before and after the sliding test of each of the shaft member and the bearing member.

[0022] Figure 7This is a graph showing the relationship between the bearing characteristic number and the friction coefficient in No. 29, No. 30, No. 34, and No. 35.

[0023] Figure 8 This is a graph showing the relationship between the bearing characteristic number and the friction coefficient in No. 31, No. 32, No. 33, No. 36, No. 37, and No. 38.

[0024] Figure 9 This is a graph showing the relationship between the bearing characteristic number and the friction coefficient for No. 85 to No. 91.

[0025] Description of Reference Numerals

[0026] 1 shaft component

[0027] 11 Outer Surface

[0028] 2 Bearing components

[0029] 21 Inner Surface

[0030] 3. Lubricating oil

[0031] 31 Oil film

[0032] P Center axis

[0033] R1: Radius of the outer surface

[0034] R2 is the radius of the inner surface. DETAILED DESCRIPTION

[0035] [Description of Embodiments of the Invention]

[0036] First, embodiments of the present invention are listed for description.

[0037] 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 supporting the outer peripheral surface of the shaft member so as to be slidable; 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 greater than or equal to 0.05 μm and less than or equal to 0.30 μm, and the height Rpk1 of the protruding peak of the outer peripheral surface is greater than or equal to 0.04 μm and less than or equal to 0.34 μm.

[0038] By optimizing the arithmetic mean roughness Ra1 and the protruding peak height Rpk1 of the outer peripheral surface of the shaft member, this bearing device facilitates maintaining a fluid-lubricated state in the sliding zone between the shaft member and the bearing member. Consequently, this bearing device can suppress the intrusion of impurities into the sliding zone and increase in cost, while also reducing frictional resistance and seizure between the shaft member and the bearing member.

[0039] Preferably, when the hardness of the shaft member is set to H1 [HV] and the hardness of the bearing member is set to H2 [HV], H1 / H2 is 4.1 or greater. Thus, when H1 / H2 is above the lower limit, the surface roughness of the bearing member is easily reduced. Consequently, frictional resistance and seizure between the shaft member and the bearing member can be further suppressed.

[0040] Preferably, when the arithmetic mean roughness of the inner circumferential surface of the bearing member is defined as Ra2 [μm] and the height of the protruding peaks on the inner circumferential surface of the bearing member is defined as Rpk2 [μm], Ra2 / Ra1 is 0.26 to 38.0, and Rpk2 / Rpk1 is 0.32 to 69.0. By controlling Ra2 / Ra1 and Rpk2 / Rpk1 within the above ranges, frictional resistance and seizure between the shaft member and the bearing member can be further suppressed.

[0041] It is preferable that the oil film thickness h [μm] calculated according to the following formula 1 is the critical oil film thickness h calculated according to the following formula 2: lim [μm] or more.

[0042] [Mathematical formula 1]

[0043]

[0044]

[0045] Thus, the oil film thickness h is the limit oil film thickness h lim As described above, it is easy to maintain the above-mentioned sliding area in a fluid lubrication state.

[0046] Preferably, the viscosity η of the lubricating oil is the critical viscosity η of the lubricating oil calculated according to the following formula 3: lim [Pa·second] or more.

[0047] [Mathematical formula 2]

[0048]

[0049] Thus, the viscosity η of the lubricating oil is the limit viscosity η of the lubricating oil.lim As a result, it is easier to maintain the sliding region in a fluid lubrication state.

[0050] Preferably, the circumferential speed u of the shaft member is the limit circumferential speed u of the shaft member calculated according to the following formula 4: lim [m / s] or more.

[0051] [Mathematical formula 3]

[0052]

[0053] Thus, the circumferential velocity u passing through the shaft member is the limit circumferential velocity u lim As a result, it is easier to maintain the sliding region in a fluid lubrication state.

[0054] Preferably, 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 according to the following formula 5: lim [m] or above.

[0055] [Formula 4]

[0056]

[0057] Thus, the equivalent radius R is the limit equivalent radius R lim As a result, it is easier to maintain the sliding region in a fluid lubrication state.

[0058] Preferably, the viscosity η of the lubricating oil satisfies the following formula 6.

[0059] 0.08×η lim ≤η<5.20×η lim ···6

[0060] As described above, since the viscosity η satisfies the above-mentioned formula 6, it is easy to adjust the viscosity of the above-mentioned lubricating oil to an appropriate level and to easily maintain the above-mentioned sliding region in a fluid lubrication state.

[0061] A driving method for a bearing device in another embodiment of the present invention includes a driving process, in which a bearing device is used to rotate the shaft member, which includes a shaft member with a shaft diameter of 180 mm or more, a bearing member that supports the outer peripheral surface of the shaft member so as to be able to slide, 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 arithmetic mean roughness Ra1 of the outer peripheral surface of the shaft member is greater than 0.05 μm and less than 0.30 μm, and the height Rpk1 of the protruding peak of the outer peripheral surface is greater than 0.04 μm and less than 0.34 μm.

[0062] The driving method of the bearing device uses the bearing device, so that in the above driving process, the sliding region between the shaft member and the bearing member is easily maintained in a fluid lubrication state. Therefore, the driving method of the bearing device can inhibit the mixing of impurities in the sliding region and the increase in cost, and can inhibit the frictional resistance and sintering between the shaft member and the bearing member.

[0063] Note that in the present application, "shaft diameter" refers to the diameter of the outer circumferential surface of the shaft member, "arithmetic average roughness" refers to a value measured in accordance with JIS-B0601 (2013), "projected peak portion 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), "fluid lubrication state" refers to a state in which fluid lubrication is classified using a stribeck curve, "limit film thickness" refers to the minimum film thickness of an oil film that can maintain a fluid lubrication state, "limit viscosity" refers to the minimum viscosity of lubricating oil that can maintain a fluid lubrication state, and "circumferential velocity of the shaft member" refers to the circumferential velocity on the outer circumferential surface of the shaft member, and "limit circumferential velocity" refers to the minimum circumferential velocity of the shaft member that can maintain a fluid lubrication state.

[0064] In the present application, "equivalent radius" refers to a value [m] calculated by the following formula 7 in a case where the radius of the outer circumferential surface of the shaft member is set to R1 [m] and the radius of the inner circumferential surface of the bearing member is set to R2 [m] (see Figure 1 ). In addition, "limit equivalent radius" refers to the minimum equivalent radius of an oil film that can maintain a fluid lubrication state.

[0065] [Formula 5]

[0066]

[0067] In the present application, the viscosity η of the lubricating oil refers to a value calculated in accordance with the following formula 8 in a case where the density of the lubricating oil is set to p [g / cm 3 ], the dynamic viscosity of the lubricating oil at a lubricating oil temperature T [K] under atmospheric pressure is set to μ(T) [mm 2 / s], and the pressure applied to the lubricating oil is set to P [GPa].

[0068] η = p μ(T) exp (a P) x 10 -3 ···8

[0069] In the above formula 8, the dynamic viscosity μ(T) is calculated in accordance with the following formula 9 using the viscosity-temperature characteristic number m.

[0070] [Formula 6]

[0071]

[0072] In the above formula 9, the above viscosity-temperature characteristic number m is calculated using the known kinematic viscosity μ1 of the lubricating oil at temperature T1 [K] and the known kinematic viscosity μ2 of the lubricating oil at temperature T2 [K] (T1 < T2) in accordance with the following formula 10 shown in the "Method for estimating kinematic viscosity and mixing ratio" of JIS-K2283 (2000).

[0073] m={loglog(μ1+0.7)-loglog(μ2+0.7)} / (logT2-logT1)···10

[0074] In the above-mentioned formula 9, b is calculated according to the following formula 11 using the known kinematic viscosity μ3 of the lubricating oil at the temperature T3 [K].

[0075] b=loglog(μ3+0.7)+mlogT3···11

[0076] In the present invention, the viscosity pressure coefficient α refers to a value [1 / GPa] calculated according to the following formula 12 as an empirical formula using the viscosity-temperature characteristic m and the kinematic viscosity μ(T).

[0077] α=m{0.1657+0.2332logμ(T)}×10...12

[0078] In the present invention, the "equivalent longitudinal elastic modulus" refers to the value [GPa] calculated by the following formula 13 when the Poisson's ratio of the shaft component is set to v1, the longitudinal elastic modulus of the shaft component is set to E1 [GPa], the Poisson's ratio of the bearing component is set to v2, and the longitudinal elastic modulus of the bearing component is set to E2 [GPa].

[0079] [Formula 7]

[0080]

[0081] 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 defined as h [μm].

[0082] [Formula 8]

[0083]

[0084] [Details of the embodiments of the present invention]

[0085] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0086] [Bearing device]

[0087] Figure 1 The bearing device of the application has: a shaft member 1; a bearing member 2 that supports an outer peripheral surface 11 of the shaft member 1 so as to be slidable; and lubricating oil 3 that is supplied to a gap between the outer peripheral surface 11 of the shaft member 1 and an inner peripheral surface 21 of the bearing member 2, and that forms an oil film 31 in the gap.

[0088] <Shaft member>

[0089] The shaft member 1 is a rotating body that rotates in the circumferential direction with respect to the bearing member 2. As the shaft member 1, for example, a crankshaft, an intermediate shaft, a propeller shaft, or the like for a ship can be given. As the material of the shaft member 1, for example, carbon steel, low alloy steel, aluminum alloy, or the like can be given. The central axis P of the shaft member 1 extends in the horizontal direction (Y direction). Figure 1

[0090] It is preferable that no coating layer such as a lubricating film be formed on the outer peripheral surface 11 of the shaft member 1. In this way, by not providing a coating layer on the outer peripheral surface 11, the mixing of impurities in the sliding region between the shaft member 1 and the bearing member 2 and the increase in cost can be suppressed.

[0091] The shaft diameter of the shaft member 1 is 180 mm or more. As the lower limit of the shaft diameter of the shaft member 1, 280 mm or 360 mm can be given. If a coating layer is provided on the outer peripheral surface 11 or the like of the shaft member 1 in the case where the shaft diameter of the shaft member 1 is the above lower limit value or more, there is a high possibility that the coating layer will be damaged and impurities will be generated. In contrast to this, this bearing device does not need to provide a coating layer on the outer peripheral surface 11, and thus the mixing of impurities in the above sliding region can be suppressed.

[0092] The upper limit of the shaft diameter of the shaft member 1 is not particularly limited, but for example, 1500 mm is preferable, and 1300 mm is more preferable. If the shaft diameter of the shaft member 1 exceeds the above upper limit value, there is a possibility that this bearing device will become excessively large and will violate the requirements for miniaturization of the device or the like.

[0093] ​There may also be multiple roughness protrusion vertices calculated according to the following steps on the outer peripheral surface 11 of the lower shaft member 1. 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), the average line of the roughness curve is set in accordance with JIS-B0601 (2013). Taking the average line as a reference, the height of the measurement point located above the average line is set to 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 set as Thr0. Next, among the measurement points on the roughness curve, the measurement points that are higher than the adjacent measurement points on both sides and have a height greater than -Thr0 are set as temporary vertices. The measurement point with the smallest height (the largest depth from the adjacent temporary vertex) among the measurement points located between adjacent temporary vertices is set as a valley. Then, for all temporary vertices, the height difference between the temporary vertex and the valleys adjacent to the temporary vertex on both sides is calculated, and vertices whose larger value of the height difference is less than 0.2×Thr0 are excluded. As a result, the remaining temporary vertices are calculated as roughness protrusion vertices.

[0094] In the case where the apex of the roughness protrusion is present on the outer peripheral surface 11 of the shaft member 1, the lower limit of the curvature radius β of the roughness protrusion in the outer peripheral surface 11 may be 55 μm or 58 μm. In the case of a shaft member 1 having a large diameter such as the shaft diameter of the shaft member 1 being greater than the above lower limit value, the dimensional accuracy caused by machining tends to become insufficient, so it is sometimes desirable to grind the outer peripheral surface 11 manually. If the outer peripheral surface 11 is ground manually, the curvature radius β of the roughness protrusion tends to become larger. If the curvature radius β of the roughness protrusion becomes larger, sintering tends to occur in the sliding area between the shaft member 1 and the bearing member 2. In such a structure, the bearing device can also easily suppress sintering in the above sliding area.

[0095] It should be noted that the above-mentioned "radius of curvature of the roughness protrusion" refers to the value calculated according to the following steps. First, a straight line is drawn toward the vertex of the roughness protrusion from all the measuring points between the vertex of the roughness protrusion and the valleys adjacent on both sides of the vertex of the roughness protrusion, and the measuring point with the largest slope of the straight line is defined as the end of the roughness protrusion. The quadratic coefficient of the quadratic function obtained by approximating the roughness curve between the two ends of each roughness protrusion by the least squares method is set to a, and the radius of curvature of each roughness protrusion is calculated by -0.5 / a. The median value of the radius of curvature of all roughness protrusions on the above-mentioned roughness curve is used as the radius of curvature of the roughness protrusion.

[0096] The arithmetic mean roughness Ra1 of the outer peripheral surface 11 of the shaft component 1 is greater than or equal to 0.05 μm and less than or equal to 0.30 μm, and the height Rpk1 of the protruding peaks of the outer peripheral surface 11 is greater than or equal to 0.04 μm and less than or equal to 0.34 μm. For the shaft component 1, if the outer peripheral surface 11 is manually ground as described above, the curvature radius β of the roughness protrusion tends to become larger. At this time, by using sandpaper with a sufficiently large grit number for grinding, the arithmetic mean roughness Ra1 and the height Rpk1 of the protruding peaks can be reduced to within the above range. For example, by using sandpaper with a coarseness of 200 grit number or more for grinding, the arithmetic mean roughness Ra1 and the height Rpk1 of the protruding peaks can be reduced to within the above range. The grit number of the above-mentioned sandpaper can be 500 grit number or more, or 600 grit number or more. Note that the arithmetic mean roughness Ra1 of the outer peripheral surface 11 of the shaft member 1 and the protruding peak height Rpk1 of the outer peripheral surface 11 can be set to values ​​before the shaft member 1 and the bearing member 2 slide.

[0097] 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 be difficult to suppress frictional resistance and seizure between the shaft member 1 and the bearing member 2.

[0098] The upper limit of the protruding peak height Rpk1 of the outer peripheral surface 11 is preferably 0.22 μm, more preferably 0.18 μm, and even more preferably 0.14 μm. If the protruding peak height Rpk1 of the outer peripheral surface 11 exceeds the upper limit, it may be difficult to suppress frictional resistance and seizure between the shaft member 1 and the bearing member 2.

[0099] <Bearing components>

[0100] Examples of the bearing member 2 include a crankshaft bearing, an intermediate bearing, a propulsion bearing, etc., which are disposed on a ship. Examples of the material of the bearing member 2 include white metal, oil film bearing alloy, and aluminum alloy.

[0101] The inner peripheral surface 21 of the bearing member 2 surrounds the outer peripheral surface 11 of the shaft member 1 along the circumferential direction. The central axis of the inner peripheral surface 21 is along the horizontal direction ( Figure 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 the lubricating oil 3. Thus, the bearing member 2 is arranged opposite the outer peripheral surface 11 via the oil film 31 on the inner peripheral surface 21, thereby slidably supporting the shaft member 1.

[0102] 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 an area (load distribution) that receives this load. The load distribution extends along the central axis of the inner circumferential surface 21 and forms an arc shape in a cross-section perpendicular to the central axis of the inner circumferential surface 21. Furthermore, the range of this load distribution can vary due to the rotation and vibration of the shaft member 1.

[0103] Preferably, no coating such as a lubricating film is formed on the inner peripheral surface 21 of the bearing member 2. By not providing a coating on the inner peripheral surface 21, the intrusion of foreign matter into the sliding region between the shaft member 1 and the bearing member 2 and the increase in cost can be suppressed.

[0104] The hardness H1 [HV] of the shaft member 1 is preferably greater than the hardness H2 [HV] of the bearing member 2. Generally, 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. Even in such a 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 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, and the friction resistance and sintering 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 does not meet 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 ratio is not particularly limited, but can be set to, for example, 20 from the viewpoint of facilitating the selection of the materials of the shaft member 1 and the bearing member 2 .

[0105] The lower limit of the ratio (Ra2 / Ra1) of the arithmetic mean roughness Ra2 [μm] of the inner peripheral surface 21 of the bearing component 2 to the arithmetic mean roughness Ra1 [μm] of the outer peripheral surface 11 of the shaft component 1 is not particularly limited, but can be set to 0.26, for example. On the other hand, the upper limit of the above ratio is preferably 38.0, more preferably 37.1, further preferably 22.6, and further preferably 20.4. If the above ratio exceeds the above upper limit, it may be difficult to suppress the frictional resistance and sintering between the outer peripheral surface 11 and the inner peripheral surface 21. It should be noted that the above ratio can be set to the ratio before the shaft component 1 and the bearing component 2 slide.

[0106] The lower limit of the ratio (Rpk2 / Rpk1) of the protruding peak portion height Rpk2 [μm] of the inner peripheral surface 21 of the bearing member 2 to the protruding peak portion height Rpk1 [μm] of the outer peripheral surface 11 of the shaft member 1 is not particularly limited, but can be set to 0.32, for example. On the other hand, the upper limit of the above ratio is preferably 69.0, more preferably 68.3, further preferably 57.3, and still further preferably 27.4. If the above ratio exceeds the above upper limit, it can be difficult to suppress the frictional resistance and the sintering between the outer peripheral surface 11 and the inner peripheral surface 21. Note that the above ratio can be set to the ratio before the shaft member 1 and the bearing member 2 slide.

[0107] < Lubricating oil >

[0108] As the lubricating oil 3, a paraffin-based base oil or the like can be given, for example. The lubricating oil 3 easily maintains the outer peripheral surface 11 and the inner peripheral surface 21 in a fluid lubrication state by forming an oil film 31.

[0109] As the oil film thickness h [μm] calculated according to the following Formula 1, the limit oil film thickness h lim [μm] or more is preferable.

[0110] [Formula 9]

[0111]

[0112]

[0113] In the above Formula 1, R denotes the equivalent radius [m] of the shaft member 1 and the bearing member 2, a denotes the viscosity pressure coefficient [1 / GPa] of the lubricating oil 3, η denotes the viscosity [Pa·sec] of the lubricating oil 3, u denotes the circumferential velocity [m / sec] of the shaft member 1, E denotes the equivalent longitudinal elastic modulus [GPa] of the shaft member 1 and the bearing member 2, and w denotes the load per unit length [N / m] applied to the bearing member 2 in the axial direction of the shaft member 1. In the above Formula 2, Λ lim denotes the value of the minimum oil film parameter at which the oil film 31 is maintained in a fluid lubrication state. Note that, in the above Formula 1, as the circumferential velocity u, the average value of the rotational speed during the continuous rotation of the shaft member 1 can be used, for example. In the above Formula 1, as the viscosity η, in the case where the maximum temperature of the lubricating oil 3 during the continuous rotation of the shaft member 1 is set to T h , η(T h). In the above formula 1, the load w per unit length can be obtained by assuming that the entire load of the shaft member 1 is directly applied to the inner peripheral surface 21 from the perspective of making it easy to calculate the oil film thickness h. Based on this assumption, the load w per unit length can be set to a value obtained by dividing the entire 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 direction of the central axis). In the above formula 1, the value Λ as the minimum oil film parameter lim , can be set to 3 or more and 4 or less according to 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 can be set to lim It is set to 3. In the above formula 2, 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.

[0114] Thus, the oil film thickness h is the limit oil film thickness h lim As described above, the oil film 31 can easily suppress solid contact between the outer peripheral surface 11 and the inner peripheral surface 21. Therefore, the fluid lubrication state between the outer peripheral surface 11 and the inner peripheral surface 21 can be easily maintained.

[0115] By using the above formula 2 and modifying the above formula 1, the critical viscosity η of the lubricating oil 3 can be obtained by the following formula 3: lim [Pa·second].

[0116] [Formula 10]

[0117]

[0118] The viscosity η [Pa·second] of the lubricating oil 3 is preferably set to the above-mentioned limit viscosity η lim That is, the lower limit of the viscosity η [Pa·second] of the lubricating oil 3 is preferably 0.08×η lim , more preferably more than 0.19×η lim , more preferably 0.37×η lim , and more preferably 0.47×η lim In addition, the lower limit of the above-mentioned viscosity η may also be the above-mentioned critical viscosity η lim On the other hand, the upper limit of the viscosity η is preferably less than 5.20×η. lim , more preferably 3.70×η lim , more preferably 1.43×η limIf the viscosity η does not meet 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, it may be difficult to reduce the frictional resistance between the outer peripheral surface 11 and the inner peripheral surface 21 due to the excessive viscosity η.

[0119] By using the above equation 2 and performing the above equation 1, the limit circumferential velocity u of the shaft member 1 can be obtained by the following equation 4: lim [m / s].

[0120] [Mathematical formula 11]

[0121]

[0122] The circumferential speed u [m / s] of the shaft member 1 is preferably set to the above-mentioned limit circumferential speed u lim That is, the lower limit of the circumferential speed u [m / s] of the shaft member 1 is preferably 0.29 × u lim , more preferably 0.53×u lim , more preferably u lim On the other hand, the upper limit of the circumferential velocity u is not particularly limited, but can be set to 4.94×u, for example. lim If the circumferential velocity u does not satisfy the lower limit, it may be difficult to maintain a fluid lubrication state between the outer circumferential surface 11 and the inner circumferential surface 21 .

[0123] By using the above equation 2 and modifying the above equation 1, the limit equivalent radius R of the shaft member 1 and the bearing member 2 can be obtained by the following equation 5: lim [m].

[0124] [Mathematical formula 12]

[0125]

[0126] The equivalent radius R [m] of the shaft member 1 and the bearing member 2 is preferably set to the above-mentioned limit equivalent radius R lim That is, the lower limit of the equivalent radius R[m] is preferably 0.08×R lim , more preferably 0.27×R lim , more preferably R lim On the other hand, the upper limit of the equivalent radius R is not particularly limited, but can be set to 25.65×R for example, based on the requirements of miniaturization of the device. lim If the equivalent radius R does not satisfy 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 .

[0127] Advantages

[0128] This bearing device optimizes the arithmetic mean roughness Ra1 and the protruding peak height Rpk1 of the outer peripheral surface 11 of the shaft member 1, thereby easily maintaining a fluid-lubricated state between the outer peripheral surface 11 and the inner peripheral surface 21. Furthermore, this bearing device eliminates the need for surface treatment layers such as coatings on the outer peripheral surface 11 and the inner peripheral surface 21. Consequently, this bearing device can suppress the intrusion of impurities between the outer peripheral surface 11 and the inner peripheral surface 21, which in turn reduces costs, while also reducing frictional resistance and seizure between the outer peripheral surface 11 and the inner peripheral surface 21.

[0129] [Driving method of bearing device]

[0130] Figure 2 The driving method of the bearing device has the use of Figure 1 The bearing device drives the shaft member 1 to rotate in a driving step S1.

[0131] <Driving process>

[0132] 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 an example of a method for supplying the lubricating oil 3, a supply port for supplying the lubricating oil 3 is provided on the inner circumferential surface 21 of the bearing member 2, and the lubricating oil 3 is supplied from the supply port so as to circulate the lubricating oil 3 in the sliding zone between the shaft member 1 and the bearing member 2. It should be noted that the lubricating oil 3 may also be dripped between the outer circumferential surface 11 and the inner circumferential surface 21 before the shaft member 1 is rotated.

[0133] In the driving step S1, it is preferable to make the oil film thickness h [μm] calculated by the following formula 1 equal to the limit oil film thickness h calculated by the following formula 2 lim The shaft member 1 is rotated so as to have a diameter of [μm] or more.

[0134] [Mathematical formula 13]

[0135]

[0136]

[0137] Thus, by controlling the oil film thickness h to the above-mentioned limit oil film thickness h lim As described above, the oil film 31 can easily suppress solid contact between the outer peripheral surface 11 and the inner peripheral surface 21 .

[0138] The viscosity η of the lubricating oil 3 in the driving step S1 is preferably set to the above-mentioned limit viscosity η. lim That is, the lower limit of the viscosity η [Pa·second] is preferably 0.08×η lim , more preferably more than 0.19×η lim, more preferably 0.37×η lim , and more preferably 0.47×η lim In addition, the lower limit of the above-mentioned viscosity η may also be the above-mentioned critical viscosity η lim On the other hand, the upper limit of the viscosity η is preferably less than 5.20×η. lim , more preferably 3.70×η lim , more preferably 1.43×η lim . If the viscosity η satisfies the lower limit, it may be difficult to maintain the fluid lubrication state between the outer peripheral surface 11 and the inner peripheral surface 21. On the contrary, if the viscosity η exceeds the upper limit, it may be difficult to reduce the frictional resistance between the outer peripheral surface 11 and the inner peripheral surface 21 because the viscosity η becomes too large. It should be noted that the viscosity η here refers to the viscosity η during the driving of the shaft member 1, and the "limit viscosity η" is used as the reference. lim The “reference control” means adjusting the driving conditions such as the circumferential speed u of the shaft member 1 and the selection of the lubricating oil 3 so as to control the limit viscosity η immediately before the start of the driving step S1. lim The viscosity η of the lubricating oil 3 in the driving step S1 is controlled as a basis.

[0139] In the driving step S1, it is preferable to drive the vehicle at the limit circumferential speed u lim The circumferential speed u of the shaft member 1 is controlled as a reference. That is, the lower limit of the circumferential speed u [m / s] of the shaft member 1 in the driving step S1 is preferably 0.29×u lim , more preferably 0.53×u lim , more preferably u lim On the other hand, the upper limit of the circumferential velocity u is not particularly limited, but can be set to 4.94×u, for example. lim If the circumferential velocity u does not satisfy the lower limit, it may be difficult to maintain a fluid lubrication state between the outer circumferential surface 11 and the inner circumferential surface 21 .

[0140] Advantages

[0141] This method of driving a bearing device facilitates maintaining a fluid-lubricated state between the outer peripheral surface 11 and the inner peripheral surface 21 during the driving step S1 by using the bearing device. Therefore, this method of driving a bearing device can suppress the intrusion of impurities between the outer peripheral surface 11 and the inner peripheral surface 21, which in turn increases costs, and can also suppress frictional resistance and seizure between the outer peripheral surface 11 and the inner peripheral surface 21.

[0142] [Other embodiments]

[0143] The above embodiments do not limit the structure of the present invention. Therefore, the above embodiments can be based on the description of this specification and common technical knowledge to perform omission, replacement or addition of constituent elements of each part of the above embodiments, and all of these should be interpreted as belonging to the scope of the present invention.

[0144] In the above 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.

[0145] [Example]

[0146] Hereinafter, the present invention will be described in detail based on Examples. However, the present invention should not be construed in a limitative manner based on the description of these Examples.

[0147] In this example, a grinding test in which the outer peripheral surface of the shaft member was manually ground and a sliding test in which the shaft member was rotated were performed.

[0148] [Grinding test]

[0149] In the grinding test, the outer peripheral surface of the shaft member was ground using sandpaper. The material of the shaft member was set to a steel material equivalent to S45C specified in JIS-G4051 (2016). The outer diameter of the shaft member in the grinding portion was set to 600 mm. The grinding was repeated while gradually increasing the grit number of the sandpaper. For each grit number of the sandpaper, the arithmetic mean roughness Ra1 and the height of the protruding peak Rpk1 on the above-mentioned outer peripheral surface after grinding were measured using a small surface roughness measuring machine ("SJ-310") manufactured by Mitutoyo Co., Ltd. In this measurement, four circumferential positions were determined at intervals of 90 degrees along the circumference of the above-mentioned outer peripheral surface, and for each of the above-mentioned circumferential positions, the arithmetic mean roughness Ra1 and the height of the protruding peak Rpk1 on the above-mentioned outer peripheral surface were measured at two measuring positions at different positions in the axial direction. In addition, the evaluation length in the above-mentioned measuring position was set to 4 mm. The measurement conditions for the arithmetic mean roughness Ra1 are as follows: a measurement force of 0.75 mN, a measuring head radius of 2 μm, a high range cutoff value (Λc) of 0.8 mm, and a low range cutoff value (Λs) of 2.5 μm. Figure 3 The measurement results of the arithmetic mean roughness Ra1 are shown in Figure 4 The measurement results of the protruding peak height Rpk1 are shown in FIG. Figure 3 as well as Figure 4 The plots in the figure represent the mean, and the error bars represent the error range relative to the mean.

[0150] like Figure 3As shown in the figure, if the grit size of the sandpaper is 150 or more, the arithmetic mean roughness Ra1 decreases to a range of 0.05 μm or more and 0.30 μm or less. On the other hand, if the grit size of the sandpaper is 200 or more, the arithmetic mean roughness Ra1 converges to a range of 0.05 μm or more and 0.20 μm or less. Figure 4 As shown in FIG, if the grit size of the sandpaper is 150 or more, the height of the protruding peak Rpk1 on the outer peripheral surface of the shaft member is reduced to a range of 0.04 μm to 0.34 μm. In addition, if the grit size of the sandpaper is 200 or more, the height of the protruding peak Rpk1 on the outer peripheral surface of the shaft member converges to a range of 0.04 μm to 0.26 μm. In other words, it is considered that in the manufacture of the shaft member accompanied by manual grinding, the arithmetic mean roughness Ra of the outer peripheral surface of the shaft member is l When the protruding peak height Rpk1 is within the above range, the surface roughness of the shaft member is reduced to near the limit. Therefore, it is believed that when the arithmetic mean roughness Ra1 and the protruding peak height Rpk1 of the outer peripheral surface of the shaft member are within the above range, frictional resistance and seizure between bearing members can be suppressed.

[0151] [Sliding test]

[0152] In the sliding test, the shaft member was rotated under the following conditions No. 1 to No. 106 using apparatus A (a friction and wear tester manufactured by Chihoda Precision Co., Ltd.), apparatus B (a bearing life tester manufactured by Chihoda Precision Co., Ltd.), and apparatus C (a friction and wear tester manufactured by Kobelco Machinery Co., Ltd.). As the shaft member, a shaft member with a manually polished outer peripheral surface was used. In apparatus A, for No. 29 to No. 38, the inner peripheral surface of the bearing member surrounding the outer peripheral surface of the shaft member within a range of approximately 90 degrees was pressed against the above-mentioned shaft member with a constant load while the shaft member was rotated. For No. 13 to No. 26 and No. 39 to No. 106, the bearing member on the flat plate was pressed against the above-mentioned shaft member with a constant load while the shaft member was rotated. In apparatus B and apparatus C, the inner peripheral surface of the bearing member surrounding the outer peripheral surface of the shaft member over the entire circumference was pressed against the above-mentioned shaft member with a constant load while the shaft member was rotated. In addition, for No. 1 to No. 106, the hardness of the shaft member and the shaft member, and the arithmetic mean roughness and the height of the protruding peak of the shaft member and the shaft member before and after the sliding test were measured. The measurement results of No. 1 to No. 106 are shown in Tables 1 to 5. 1A Refers to the arithmetic mean roughness of the shaft component before the sliding test, Ra 1BRefers to the arithmetic mean roughness of the shaft component after the sliding test, Ra 2A Refers to the arithmetic mean roughness of the bearing component before the sliding test, Ra 2B Refers to the arithmetic mean roughness of the bearing component after the sliding test. In addition, in Tables 1 to 5, Rpk 1A Refers to the protruding peak height of the shaft component before the sliding test, Rpk 1B Refers to the protruding peak height of the shaft component after the sliding test, Rpk 2A Refers to the protruding peak height of the bearing component before the sliding test, Rpk 2B Refers to the height of the protruding peak after the sliding test of the bearing component. In addition, the "hardness ratio", "arithmetic mean roughness ratio" and "protruding peak height ratio" shown in Tables 1 to 5 are values ​​calculated with a valid digit of 4. It should be noted that in this sliding test, for hardness, the shaft components of No.1 to No.28 and the bearing components of No.13 to No.26 were measured using a Vickers hardness tester ("FV-310") made by (stock company) FUTURE-TECH, the bearing components of No.1 to No.12 and No.27 to No.28 were measured using a Vickers hardness tester ("MVK-E") made by (stock company) Akashi Manufacturing, and the shaft components of No.29 to No.106 and the bearing components were measured using a Vickers hardness tester ("AVK") made by (stock company) Akashi Manufacturing. The arithmetic mean roughness and protruding peak height were measured for shaft components and bearing components No. 1 to No. 28 using a small surface roughness measuring instrument ("SJ-310") manufactured by Mitutoyo Co., Ltd., and for shaft components and bearing components No. 29 to No. 106 using a small surface roughness measuring instrument ("SJ-210") manufactured by Mitutoyo Co., Ltd. The arithmetic mean roughness and protruding peak height were measured using a 4 mm evaluation length for components No. 1 to No. 28 and a 12.5 mm evaluation length for components No. 29 to No. 106. The measurement conditions of the arithmetic mean roughness are set as a measuring force of 0.75 mN, a measuring sub-radius of 2 μm, a high-range cutoff value (Λc) of 0.8 mm, and a low-range cutoff value (Λs) of 2.5 μm in No. 1 to No. 28; and as a measuring force of 4 mN, a measuring sub-radius of 5 μm, a high-range cutoff value (Λc) of 2.5 mm, and a low-range cutoff value (Λs) of 8 μm in No. 29 to No. 106.

[0153] (No.1 to No.3)

[0154] In No. 1 to No. 3, the load from the bearing member to the shaft member was set to 10 kN. For the rotational speed of the shaft member, the initial rotational speed was set to 3000 rpm, and was decreased by 250 rpm at intervals of 10 minutes, and the minimum was decreased to 250 rpm. As the shaft member, manganese steel was used, and as the bearing member, white metal of WJ1 prescribed by JIS-H5401 (1958) was used. As the lubricating oil, "FBK oil RO32" manufactured by ENEOS (Co. Ltd.) was used. The lubricating oil was supplied to the sliding region between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member at an initial temperature of 70°C, the sliding region was immersed in the above lubricating oil, and the above lubricating oil was circulated.

[0155] (No. 4 to No. 12)

[0156] In No. 4 to No. 12, the rotational speed of the shaft member was set to be constant at 3500 rpm. For the load from the bearing member to the shaft member, the initial load was set to 0 kN, and was increased by 0.5 kN at intervals of 5 minutes, and the maximum was increased to 20 kN. As the shaft member, manganese steel was used, and as the bearing member, white metal equivalent to WJ1 prescribed by JIS-H5401 (1958) was used. As the lubricating oil, "FBK oil RO32" manufactured by ENEOS (Co. Ltd.) was used. The lubricating oil was supplied to the sliding region between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member at an initial temperature of 70°C, and was circulated in the sliding region.

[0157] (No. 13 to No. 17)

[0158] In No. 13 to No. 17, the rotational speed of the shaft member was set to 400 rpm in No. 13, 200 rpm in No. 14, 100 rpm in No. 15, 50 rpm in No. 16, and 800 rpm in No. 17. For the load from the bearing member to the shaft member, the initial load was set to 0 kN, and was increased by 0.1 kN at intervals of 1 minute, and was increased to 1 kN. As the shaft member, steel material of S45C prescribed by JIS-G4051 (2016) was used, and as the bearing member, white metal of WJ2 prescribed by JIS-H5401 (1958) was used. As the lubricating oil, "FBK oil RO32" manufactured by ENEOS (Co. Ltd.) was used. The lubricating oil was supplied to the sliding region between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member at room temperature, and was circulated in the sliding region.

[0159] (No. 18 and No. 25)

[0160] In No. 18 and No. 25, the shaft member was rotated for 240 minutes, with the rotational speed of the shaft member maintained at 50 rpm and the load from the bearing member to the shaft member maintained at 1 kN. In No. 18 and No. 25, the same shaft member and bearing member as in No. 13 to No. 17 were used, except for the hardness and surface roughness. Furthermore, the same lubricating oil was used, and the circulation was performed in the same manner as in No. 13 to No. 17.

[0161] (No.19 and No.26)

[0162] In No. 19 and No. 26, the shaft member's rotational speed was kept constant at 100 rpm, and the load from the bearing member to the shaft member was kept constant at 1 kN. The shaft member was rotated for 240 minutes. In No. 19 and No. 26, the same shaft member and bearing member as those in No. 13 to No. 17 were used, except for hardness and surface roughness. The lubricant used was the same as in No. 13 to No. 17. The lubricant was dripped once at room temperature into the sliding zone 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.

[0163] (No.20 to No.24)

[0164] In No. 20 to No. 24, the shaft member rotational speed was set to 400 rpm in No. 20, 200 rpm in No. 21, 100 rpm in No. 22, 50 rpm in No. 23, and 800 rpm in No. 24. The drive conditions for No. 20 to No. 24 were identical to those for No. 13 to No. 17, except for the shaft member rotational speed. In No. 20 to No. 24, the same shaft member and bearing member as those for No. 13 to No. 17 were used, except for the hardness and surface roughness. Furthermore, the same lubricating oil was used and circulated in the same manner as for No. 13 to No. 17.

[0165] (No.27 and No.28)

[0166] In Nos. 27 and 28, the same driving conditions as in Nos. 1 to 3 were used, except that the shaft member rotational speed was reduced at one-minute intervals. 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 hardness and surface roughness. Furthermore, the same lubricating oil was used, and the circulation was performed in the same manner as in Nos. 1 to 3.

[0167] (No. 29 to No. 38)

[0168] In No. 29 to No. 38, the rotational speed of the shaft member was set to 200 rpm in No. 29, 800 rpm in No. 30, 100 rpm in No. 31, 200 rpm in No. 32, 800 rpm in No. 33, 200 rpm in No. 34, 800 rpm in No. 35, 100 rpm in No. 36, 200 rpm in No. 37, and 800 rpm in No. 38. As for the load from the bearing member to the shaft member, the initial load was set to 0 kN, and was increased by 0.1 kN at 1-minute intervals and increased to 1 kN. As the shaft member, a steel material of S45C prescribed by JIS-G4051 (2016) was used, and as the bearing member, a white alloy of WJ2 prescribed by JIS-H5401 (1958) was used. As the lubricating oil, "FBK oil RO100" manufactured by ENEOS (K.K.) was used in No. 29, No. 30, No. 34, and No. 35, and "FBK oil RO32" manufactured by ENEOS (K.K.) was used in No. 31 to No. 33 and No. 36 to No. 38. The lubricating oil was dripped once 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.

[0169] In No. 29 to No. 38, the temperature [°C] was measured by a thermocouple installed at a position of 2 mm in depth from the surface of the bearing member, and the temperature was taken as the temperature of the lubricating oil. In addition, in No. 29 to No. 38, the frictional force at the time of rotation of the shaft member was measured by a load cell installed to a holder that held the bearing member, and the friction coefficient μ was calculated by dividing the frictional force by the load applied. These measured values were used in the evaluation of the fluid lubrication state and the calculation of the oil film thickness described later.

[0170] (No. 39 to No. 42)

[0171] In No. 39 to No. 42, the rotational speed of the shaft member was set to 100 rpm and maintained constant, and the load from the bearing member to the shaft member was set to 1 kN and maintained constant, and the shaft member was rotated for a maximum of 900 minutes. It should be noted that due to the constraints of the device, the test was interrupted at this point when the friction force measured by the load cell installed in the retainer holding the bearing member reached approximately 294 kN or above, or the temperature measured by the thermocouple installed at a depth of 2 mm from the surface of the bearing member reached 100°C or above. As the shaft member, S45C steel specified in JIS-G4051 (2016) was used, and as the bearing member, WJ2 white alloy specified in JIS-H5401 (1958) was used. As the lubricant, "FBK Oil RO32" manufactured by ENEOS (Co., Ltd.) was used. The lubricant was dripped only once at the beginning of the sliding test into the sliding area between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member at 20°C.

[0172] (No.43 to No.45)

[0173] In No. 43 to No. 45, the rotational speed of the shaft component was set to 200 rpm in No. 43 and to 100 rpm in No. 44 and No. 45. In addition, the load from the bearing component to the shaft component was set to 1 kN and kept constant, and the shaft component was rotated for a maximum of 320 minutes. It should be noted that, due to the constraints of the device, when the friction force measured by the load cell installed on the retainer holding the bearing component became approximately 294 kN or more, or when the temperature measured by the thermocouple installed at a depth of 2 mm from the surface of the bearing component became 100°C or more, the test was interrupted at that time. In No. 43 to No. 45, the same shaft components and bearing components as those of No. 39 to No. 42 were used except for hardness and surface roughness. In addition, the lubricating oil was set to be the same as that of No. 39 to No. 42. In No. 43, lubricating oil was dripped into the sliding area between the outer peripheral surface of the shaft component and the inner peripheral surface of the bearing component only once at 20° C. at the beginning of the sliding test. In No. 44 and No. 45, lubricating oil was supplied to the above-mentioned sliding area at 20° C., so that the sliding area was immersed in the above-mentioned lubricating oil and the above-mentioned lubricating oil was circulated.

[0174] (No.46 to No.84)

[0175] In No. 46 to No. 84, the rotation time of the shaft member is set to 1 minute in No. 46 and No. 65, 5 minutes in No. 47 and No. 66, 10 minutes in No. 48 and No. 67, 20 minutes in No. 49 and No. 68, 30 minutes in No. 50 and No. 69, 40 minutes in No. 51 and No. 70, 50 minutes in No. 52 and No. 71, 60 minutes in No. 53 and No. 72, 90 minutes in No. 54 and No. 73, 10 minutes in No. 55 and No. 74. The driving time was 20 minutes, 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. The other driving conditions for No. 46 to No. 84 were the same as for No. 39 to No. 42. In No. 46 to No. 84, the same shaft members and bearing members as those for No. 39 to No. 42 were used, except for the hardness and surface roughness. In addition, as lubricating oil, "FBK Oil RO32" manufactured by ENEOS Co., Ltd. was used in No. 46 to No. 64, and "FBK Oil RO100" manufactured by ENEOS Co., Ltd. was used in No. 65 to No. 84. Similar to No. 39 to No. 42, the lubricating oil was dripped only once at the beginning of the sliding test at 20°C.

[0176] (No.85 to No.91)

[0177] In No. 85 to No. 91, the rotational speed of the shaft member was set to 100 rpm in No. 85, 200 rpm in No. 86, 800 rpm in No. 87, 800 rpm in No. 88, 100 rpm in No. 89, 200 rpm in No. 90, and 800 rpm in No. 91. For the load from the bearing member to the shaft member, the initial load was set to 0 kN, and the load was increased by 0.1 kN at intervals of 1 minute to 1 kN. As the shaft member, S45C steel specified in JIS-G4051 (2016) was used, and as the bearing member, an Al-Sn-Cu alloy (hereinafter referred to as an aluminum alloy) having a Sn content of 7.0 mass% and a Cu content of 2.5 mass% was used. As the lubricating oil, "FBK Oil RO100" manufactured by ENEOS (Co., Ltd.) was used. The lubricating oil was dripped only once at room temperature into the sliding region between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member at the start of the sliding test.

[0178] In Nos. 85 to 91, the temperature of the lubricating oil and the friction coefficient μ were determined in the same manner as in Nos. 29 to 38. These measured values ​​were used in the evaluation of the fluid lubrication state and the calculation of the oil film thickness described later.

[0179] (No.92 to No.106)

[0180] In Nos. 92 to 106, the rotation speed of the shaft member was set to 800 rpm and maintained constant, the load from the bearing member to the shaft member was set to 0.3 kN and maintained constant, and the rotation time of the shaft member was set to 1 minute in Nos. 92 and 100, 5 minutes in Nos. 93 and 101, 10 minutes in Nos. 94 and 102, 20 minutes in Nos. 95 and 103, 30 minutes in Nos. 96 and 104, 40 minutes in Nos. 97 and 105, 50 minutes in Nos. 98 and 106, and 60 minutes in No. 99. In Nos. 92 to 106, the same shaft members and bearing members as those in Nos. 85 to 91 were used, except for the hardness and surface roughness. In addition, "FBK Oil RO32" manufactured by ENEOS Co., Ltd. was used as the lubricating oil, and similarly to No. 39 to No. 42, it was dripped only once at the start of the sliding test at 20°C.

[0181] [Table 1]

[0182]

[0183] [Table 2]

[0184]

[0185] [Table 3]

[0186]

[0187] [Table 4]

[0188]

[0189] [Table 5]

[0190]

[0191] (sintering)

[0192] Under conditions No. 1 to No. 106, no transfer of material from the shaft member to the bearing member or from the bearing member to the shaft member, which would have hindered the surface roughness measurement after the sliding test, was observed. In other words, no visible condensation was confirmed on the outer circumferential surface of the shaft member or the inner circumferential surface of the bearing member after the sliding test.

[0193] (hardness)

[0194] exist Figure 5 The figure shows the ratio of the hardness H1 of the shaft member to the hardness H2 of the bearing member (H1 / H2) as the horizontal axis and the ratio of the arithmetic mean roughness Ra as the horizontal axis for No. 1 to No. 106. 1B / Ra 1A and Ra 2B / Ra 2A Set the vertical axis of the chart. Figure 6 The figure shows the ratio Rpk of the height of the protruding peaks with H1 / H2 as the horizontal axis for No. 1 to No. 12, No. 27, No. 28, and No. 39 to No. 106. 1B / Rpk 1A The graph with the vertical axis and the ratio of the height of the protruding peak Rpk with H1 / H2 as the horizontal axis for No. 1 to No. 28 and No. 39 to No. 106 are shown. 2B / Rpk 2A The vertical axis of the chart is set as Figure 5 as well as Figure 6 The H1 / H2 value of No. 13 to No. 19 in the horizontal axis represents the average value of the H1 / H2 value of No. 13 to No. 19. Figure 5 as well as Figure 6 The points are the mean, and the error bars are the error range relative to the mean.

[0195] like Figure 5 as well as Figure 6As shown in FIG, the arithmetic mean roughness of the outer peripheral surface of the shaft component and the height of the protruding peaks 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 component showed a tendency to decrease after the sliding test (Ra 2B / Ra 2A <1). In addition, the height of the protruding peak of the bearing component tends to decrease after the sliding test when the hardness ratio H1 / H2 is 4.1 or more (Rpk 2B / Rpk 2A <1). This shows that by setting the hardness ratio H1 / H2 to 4.1 or more, it is easy to grind the inner peripheral surface of the bearing member by utilizing the sliding movement with the shaft member.

[0196] (Arithmetic mean roughness ratio)

[0197] According to 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 is 2A The arithmetic mean roughness Ra of the inner peripheral surface of the bearing member after the sliding test is 0.34 μm or more and 1.85 μm or less. 2B It is greater than 0.08 μm and less than 1.24 μm. Therefore, it is considered that the arithmetic mean roughness Ra2 of the inner circumferential surface of the bearing component is in the range of greater than 0.08 μm and less than 1.85 μm before and after the sliding test. On the other hand, as described above, it is considered that when the surface roughness of the shaft component is reduced to near the limit, the arithmetic mean roughness Ra1 of the outer circumferential surface of the shaft component can be controlled to be greater than 0.05 μm and less than 0.30 μm. Based on these matters, it is considered that the ratio of the arithmetic mean roughness Ra2 of the inner circumferential surface of the bearing component to the arithmetic mean roughness Ra1 of the outer circumferential surface of the shaft component (Ra2 / Ra1) can be controlled to be within the range of 0.27 obtained by dividing 0.08 by 0.30 as the lower limit value and 37.0 obtained by dividing 1.85 by 0.05 as the upper limit value.

[0198] According to Table 5, when an aluminum alloy is used for the bearing member, the arithmetic mean roughness Ra of the inner peripheral surface of the bearing member before the sliding test is 2A The arithmetic mean roughness Ra of the inner peripheral surface of the bearing member after the sliding test is 0.54 μm or more and 0.83 μm or less. 2BIt is greater than 0.21 μm and less than 1.02 μm. Therefore, it is considered that the arithmetic mean roughness Ra2 of the inner circumferential surface of the bearing component is in the range of greater than 0.21 μm and less than 1.02 μm before and after the sliding test. On the other hand, as described above, it is considered that when the surface roughness of the shaft component is reduced to near the limit, the arithmetic mean roughness Ra1 of the outer circumferential surface of the shaft component can be controlled to be greater than 0.05 μm and less than 0.30 μm. Based on these matters, it is considered that the ratio of the arithmetic mean roughness Ra2 of the inner circumferential surface of the bearing component to the arithmetic mean roughness Ra1 of the outer circumferential surface of the shaft component (Ra2 / Ra1) can be controlled to be within the range of 0.70 obtained by dividing 0.21 by 0.30 as the lower limit value and 20.4 obtained by dividing 1.02 by 0.05 as the upper limit value.

[0199] Based on 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.

[0200] (Ratio of protruding peak height)

[0201] According to Tables 1 to 4, when white metal is used for the bearing member, the protruding peak height Rpk of the inner peripheral surface of the bearing member before the sliding test is 2A The height Rpk of the protruding peak on the inner peripheral surface of the bearing member after the sliding test is 0.40 μm or more and 2.29 μm or less. 2B It is greater than 0.11 μm and less than 0.99 μm. Therefore, it is considered that the height of the protruding peak Rpk2 on the inner peripheral surface of the bearing component is in the range of greater than 0.11 μm and less than 2.29 μm before and after the sliding test. On the other hand, as described above, it is considered that when the surface roughness of the shaft component is reduced to near the limit, the height of the protruding peak Rpk1 on the outer peripheral surface of the shaft component can be controlled to be greater than 0.04 μm and less than 0.34 μm. Based on these matters, it is considered that the ratio of the height of the protruding peak Rpk2 on the inner peripheral surface of the bearing component to the height of the protruding peak Rpk1 on the outer peripheral surface of the shaft component (Rpk2 / Rpk1) can be controlled to be within the range of 0.32 obtained by dividing 0.11 by 0.34 as the lower limit value and 57.3 obtained by dividing 2.29 by 0.04 as the upper limit value.

[0202] According to Table 5, when an aluminum alloy is used for the bearing member, the protruding peak height Rpk of the inner peripheral surface of the bearing member before the sliding test is 2A The height Rpk of the protruding peak on the inner peripheral surface of the bearing member after the sliding test is 0.98 μm or more and 1.66 μm or less. 2BIt is greater than 0.16 μm and less than 2.73 μm. Therefore, it is considered that the height of the protruding peak Rpk2 on the inner peripheral surface of the bearing component is in the range of greater than 0.16 μm and less than 2.73 μm before and after the sliding test. On the other hand, as described above, it is considered that when the surface roughness of the shaft component is reduced to near the limit, the height of the protruding peak Rpk1 on the outer peripheral surface of the shaft component can be controlled to be greater than 0.04 μm and less than 0.34 μm. Based on these matters, it is considered that the ratio of the height of the protruding peak Rpk2 on the inner peripheral surface of the bearing component to the height of the protruding peak Rpk1 on the outer peripheral surface of the shaft component (Rpk2 / Rpk1) can be controlled to be within the range of 0.47 obtained by dividing 0.16 by 0.34 as the lower limit value and 68.3 obtained by dividing 2.73 by 0.04 as the upper limit value.

[0203] Based on the above, it is considered that the ratio (Rpk2 / Rpk1) of the protruding peak height Rpk2 on the inner peripheral surface of the bearing member to the protruding peak height Rpk1 on the outer peripheral surface of the shaft member can be controlled within the range of 0.32 to 68.3.

[0204] (Fluid lubrication state)

[0205] Regarding No. 29 to No. 38 and No. 85 to No. 91, the horizontal axis is the bearing characteristic number [m -1 ], set the vertical axis to the friction coefficient and plot the value for each load condition. Figure 7 、 Figure 8 as well as Figure 9 The results are shown in FIG. It should be noted that the bearing characteristic number is calculated by viscosity η [Pa·second] × circumferential speed u [m / second] / P (load [N] × 10 -6 ) The viscosity η is calculated using the known density ρ of the lubricating oil at 15°C according to Formula 8.

[0206] like Figure 7 as well as Figure 8 As shown, inflection points are observed in the region with low bearing characteristic numbers for No. 31 and No. 32. In other words, it is believed that in No. 31 and No. 32, when the bearing characteristic numbers are low, a transition from fluid lubrication to mixed lubrication occurs. Meanwhile, No. 29, No. 30, and No. 33 to No. 38 are believed to be in fluid lubrication.

[0207] like Figure 9As shown, an inflection point is observed in No. 85, indicating a transition from a fluid lubrication state to a mixed lubrication state. Meanwhile, in Nos. 86 to 91, the friction coefficients shift at low values ​​regardless of the bearing characteristic number, indicating a fluid lubrication state.

[0208] (Oil film thickness)

[0209] For No. 29 to No. 38 and No. 85 to No. 91, the oil film thickness h [μm] was calculated using the above-mentioned formula 1. Here, the viscosity pressure coefficient α was calculated using the above-mentioned formula 12. In addition, u is obtained by converting the rotational speed of the shaft member into units of m / s, and w is obtained by dividing the load [N] applied to the shaft member by the pressure of the bearing member by the width of the inner circumferential surface of the bearing member. The calculation results are shown in Table 6. It should be noted that the oil film thickness h shown in Table 6 is the value when the above-mentioned bearing characteristic number is minimum.

[0210] (Limiting oil film thickness)

[0211] For No.29 to No.38 and No.85 to No.91, the oil film parameter Λ lim The critical oil film thickness h before the sliding test is calculated by setting it to 3 and using the above formula 2. limA [μm] and the critical oil film thickness h after the sliding test limB [μm]. Table 6 shows the calculation results.

[0212] (Limiting viscosity)

[0213] For No. 29 to No. 38 and No. 85 to No. 91, the critical oil film thickness h is used. limA The critical viscosity η before the sliding test was calculated using the above formula 3: limA , and use the limit oil film thickness h limB The critical viscosity η after the sliding test was calculated using the above formula 3: limB The calculation results are shown in Table 6. Note that the critical viscosity shown in Table 6 is the value when the above-mentioned bearing characteristic number is the minimum.

[0214] (Ratio of viscosity to critical viscosity)

[0215] The ratio of viscosity η to the critical viscosity was calculated for the lubricating oils Nos. 29 to 38 and 85 to 91. The results are shown in Table 6. The viscosity η for the lubricating oils Nos. 29 to 38 and 85 to 91 was calculated as the product of the known kinematic viscosity at 40°C and the known density at 15°C, with the lubricating oil temperature at 40°C as the reference. The "ratio of viscosity to the critical viscosity" shown in Table 6 is a value calculated with four significant figures.

[0216] [Table 6]

[0217]

[0218] (Evaluation of viscosity)

[0219] As shown in Table 6, when white metal is used as the bearing member, the viscosity η is relative to the critical viscosity η before the sliding test. limA The ratio (η / η limA ), satisfying 0.19<η / η limA No. 29, No. 30, No. 33 to No. 35, No. 37 and No. 38 with a value less than 5.20 are in a fluid lubrication state. limA No. 31 and No. 32 with a value of ≤ 0.19 failed to maintain the fluid lubrication state.

[0220] When an aluminum alloy is used for the bearing member, the viscosity η is relative to the critical viscosity η before the sliding test. limA The ratio (η / η limA ), satisfying 0.08≤η / η limA No.86 to No.91 with a value less than 5.20 are in a fluid lubrication state. On the other hand, η / η limA No. 85 with a viscosity less than 0.08 failed to maintain the fluid lubrication state.

[0221] Industrial Applicability

[0222] The bearing device according to one aspect of the present invention can suppress the incorporation of impurities and an increase in cost, and can suppress frictional resistance and seizure between the shaft member and the bearing member. Therefore, it can be applied to a bearing device for ships, for example.

Claims

1. A bearing device comprising: Shaft components with 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 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 shaft component is a marine crankshaft, intermediate shaft or propeller shaft, 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, When the arithmetic mean roughness of the inner circumferential surface of the bearing component is Ra2 [μm] and the height of the protruding peaks of the inner circumferential surface of the bearing component is Rpk2 [μm], Ra2 / Ra1 is greater than or equal to 0.26 and less than or equal to 38.0, and Rpk2 / Rpk1 is greater than or equal to 0.32 and less than or equal to 69.

0.

2. The bearing device according to claim 1, wherein: When the hardness of the shaft member is H1 [HV] and the hardness of the bearing member is H2 [HV], H1 / H2 is 4.1 or more.

3. A method for driving a bearing device, wherein: The driving method of the bearing device includes a driving step in which the shaft member is rotated using a bearing device including a shaft member having a shaft diameter of 180 mm or greater, a bearing member slidably supporting an outer peripheral surface of the shaft member, and lubricating oil supplied to a gap between the outer peripheral surface of the shaft member and an inner peripheral surface of the bearing member to form an oil film in the gap. The shaft component is a marine crankshaft, intermediate shaft or propeller shaft, 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, When the arithmetic mean roughness of the inner circumferential surface of the bearing component is Ra2 [μm] and the height of the protruding peaks of the inner circumferential surface of the bearing component is Rpk2 [μm], Ra2 / Ra1 is greater than or equal to 0.26 and less than or equal to 38.0, and Rpk2 / Rpk1 is greater than or equal to 0.32 and less than or equal to 69.

0.

4. The driving method of the bearing device according to claim 3, wherein: The oil film thickness h [μm] calculated by the following formula 1 is the critical oil film thickness h calculated by the following formula 2 lim [μm] or more, In the above formula (1), R refers to the equivalent radius of the shaft member and the bearing member [m], α refers to the viscosity pressure coefficient of the lubricating oil [1 / GPa], η refers to the viscosity of the lubricating oil [Pa·second], u refers to the circumferential speed of the shaft member [m / second], E refers to the equivalent longitudinal elastic modulus of the shaft member and the bearing member [GPa], w refers to the load applied to the bearing member per unit length in the axial direction of the shaft member [N / m], and in the above formula (2), Λ lim It refers to the minimum oil film parameter value for the oil film to maintain the fluid lubrication state, and Ra2 refers to the arithmetic mean roughness [μm] of the inner peripheral surface of the bearing member.

5. The driving method of the bearing device according to claim 4, wherein: The viscosity η of the lubricating oil is the critical viscosity η of the lubricating oil calculated according to the following formula 3: lim [Pa·second] or more, 。 6. The driving method of the bearing device according to claim 4, wherein: The circumferential speed u of the shaft member is the limit circumferential speed u of the shaft member calculated according to the following formula 4: lim [m / s] or more, 。 7. The driving method of a bearing device according to claim 4, wherein: 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 according to the following formula 5: lim [m] and above, 。 8. The driving method of a bearing device according to claim 3, wherein: The viscosity η of the lubricating oil satisfies the following formula 6: 0.08×η lim ≤η<5.20×η lim · · · 6 Wherein, in the formula 6, η lim It refers to the critical viscosity [Pa·second] of the lubricating oil calculated according to the following formula 3 under the following circumstances: the equivalent radius of the shaft member and the bearing member is set to R [m], the viscosity pressure coefficient of the lubricating oil is set to α [1 / GPa], the viscosity of the lubricating oil is set to η [Pa·second], the circumferential speed of the shaft member is set to u [m / second], the equivalent longitudinal elastic modulus of the shaft member and the bearing member is set to E [GPa], the load per unit length in the axial direction of the shaft member applied to the bearing member is set to w [N / m], and the minimum value of the oil film parameter for the oil film to maintain a fluid lubrication state is set to Λ lim , the arithmetic mean roughness of the inner peripheral surface of the bearing component is set to Ra2, 。

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