Holder and rolling bearing

Abstract

To provide a holder capable of improving quietness of a rolling bearing, and a rolling bearing.SOLUTION: A holder holds the plurality of rolling elements in a rolling bearing comprising the plurality of rolling elements and a pair of raceway members sandwiching the rolling elements, the holder comprising a metal member containing defects. The metal member has a housing part for housing the rolling elements, and a defect rate, which is the volumetric ratio of the defects in the metal member, is 0.020 vol.% or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a retainer and a rolling bearing. [Background technology]

[0002] A rolling bearing such as a thrust ball bearing includes a plurality of rolling elements, a cage that holds the plurality of rolling elements, and a pair of raceway members that sandwich the rolling elements. The cage holds the plurality of rolling elements at regular intervals, and from the viewpoint of strength, it is sometimes made of a metal material that contains brass or the like (for example, see the following patent document). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-146922 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the rolling bearing described in Patent Document 1 has room for improvement in terms of noise reduction during use.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide a cage and a rolling bearing that can improve noise reduction during use of the rolling bearing. [Means for solving the problem]

[0006] As a result of extensive investigations aimed at solving the above problems, the inventors of the present disclosure have found that the above problems can be solved by the following disclosure.

[0007] That is, one aspect of the present disclosure provides a retainer for holding a plurality of rolling elements in a rolling bearing comprising a plurality of rolling elements and a pair of raceway members sandwiching the rolling elements, the retainer comprising a metal member containing defects, the metal member having an accommodating portion for accommodating the rolling elements, and a defect rate, which is the volumetric percentage of the defects in the metal member, of 0.020 volume % or more. In a rolling bearing, because there is a gap between the rolling elements and the inner wall surface of the housing, when the rolling bearing is in use, the rolling elements collide with the inner wall surface of the housing. In this case, according to the above-mentioned retainer, the metal member contains defects, and the defect rate in the metal member is 0.020 volume % or more, so that the collision sound when the rolling elements collide with the inner wall surface of the housing is easily absorbed and attenuated by the defects, and therefore the retainer can improve the quietness of the rolling bearing when it is in use.

[0008] In the cage, it is preferable that the defect rate in the metal member is 4.756 volume % or less. In this case, by making the defect rate in the metal member 4.756 volume % or less, it is possible to suppress a decrease in the mechanical strength of the metal member. Furthermore, when stress is applied to the cage, if there is a defect such as a cavity nearby, it is possible that this will become the starting point for damage. It is advisable to carry out a strength analysis in advance, and if it appears that stress will be applied, to ensure that there are no cavity on the external surface, and if there is a cavity inside, to control the size of the cavity so that it is strong enough to withstand. In such cases, it is advisable to possess and utilize data summarizing the relationship between strength and size of the defect.

[0009] In the cage, the metal member is preferably an aluminum alloy or a magnesium alloy. When the metal member includes an aluminum alloy or a magnesium alloy, the cage is lighter. In this case, the cage is less likely to deform due to centrifugal force when the rolling bearing is in use. Therefore, the positional deviation of the rolling elements due to the deformation of the housing part of the cage is suppressed. In addition, the cage and the raceway member are less likely to come into contact with each other, and it is possible to suppress an increase in the rotational resistance of the rolling bearing, and collision noise and seizure due to collision between the cage and the raceway member. Furthermore, since the cage is lighter, the rolling bearing is also lighter, so it is possible to reduce the initial rotation loss torque of the rolling bearing, and the energy required to rotate the rolling bearing can be reduced, which can contribute to reducing CO2. Furthermore, since the aluminum alloy or magnesium alloy has a low density, vibrations are easily attenuated. Therefore, the cage can immediately attenuate any sound that may be generated.

[0010] In the cage, it is particularly preferable that the metal member is an aluminum alloy. Since aluminum alloys have a higher Young's modulus than magnesium alloys, they are less likely to distort even when centrifugal force is applied to the cage during use of the rolling bearing, which suppresses deformation of the housing portion and thus further suppresses displacement of the rolling elements due to deformation of the housing portion of the cage.

[0011] The rolling bearing using the cage may be a thrust ball bearing.

[0012] It is preferable that the cage further has a surface protection layer for protecting the surface of the metal member. By the retainer further having a surface protective layer, the retainer is less likely to affect the noise reduction properties of a rolling bearing using the retainer when in use, and the wear resistance of the rolling bearing using the retainer can be improved.

[0013] In the cage, the surface protective layer is preferably a coating obtained by subjecting the metal member to an anodizing treatment. In this case, the cage can further improve the wear resistance of the rolling bearing in which the cage is used.

[0014] In the cage, the surface protection layer preferably has a thickness of 10 μm to 25 μm. In this case, the retainer is less likely to reduce the wear resistance of the rolling bearing using the retainer, and the surface protective layer is less likely to fall off when the rolling bearing using the retainer is in use.

[0015] Another aspect of the present disclosure provides a rolling bearing comprising a plurality of rolling elements, a retainer that holds the plurality of rolling elements, and a pair of raceway members that sandwich the rolling elements, the retainer being the retainer described above. In a rolling bearing, because there is a gap between the rolling elements and the inner wall surface of the housing, the rolling elements collide with the inner wall surface of the housing when the rolling bearing is in use. In this case, according to the above rolling bearing, the metal member of the cage contains defects, and the defect rate in the metal member is 0.020 volume % or more, so that the collision sound when the rolling elements collide with the inner wall surface of the housing is easily absorbed and attenuated by the defects, and therefore the rolling bearing can improve noise reduction when in use. Effect of the Invention

[0016] According to the present disclosure, a cage and a rolling bearing are provided that can improve noise reduction during use of the rolling bearing. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic cross-sectional view showing an embodiment of a rolling bearing according to one aspect of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing an embodiment of a rolling bearing according to one aspect of the present disclosure.

[0019] As shown in FIG. 1, the rolling bearing 100 of this embodiment is a thrust ball bearing, and includes a plurality of rolling elements 40, a ring-shaped retainer 30 that holds the plurality of rolling elements 40, and a pair of raceway members 10, 20 that sandwich the rolling elements 40.

[0020] The cage 30 holds a plurality of rolling elements 40 arranged at regular intervals, and includes a metal member 31 including a defect 33. The defect rate, which is the volume ratio of the defects 33 in the metal member 31, is 0.020 volume % or more. The metal member 31 has receiving portions 32 for receiving the respective rolling elements 40 .

[0021] The accommodation portion 32 is a through hole, and the rolling element 40 protrudes from the accommodation portion 32 and is in contact with the raceway member 10 and the raceway member 20, respectively. Lubricating oil and grease are interposed between the rolling elements 40 and the raceway members 10, 20 to reduce friction therebetween.

[0022] In the rolling bearing 100, because there is a gap between the rolling elements 40 and the inner wall surface of the housing portion 32, the rolling elements 40 collide with the inner wall surface of the housing portion 32 when the rolling bearing 100 is in use. At this time, according to the rolling bearing 100, the metal member 31 of the cage 30 contains defects 33, and the defect rate, which is the volume ratio of the defects 33 in the metal member 31, is 0.020 volume % or more, so that the collision sound when the rolling elements 40 collide with the inner wall surface of the housing portion 32 is easily absorbed and attenuated by the defects 33, and therefore the rolling bearing 100 can improve noise reduction during use.

[0023] The raceway members 10, 20, the rolling elements 40 and the cage 30 will be described in detail below.

[0024] (Railway components) The material constituting the track members 10, 20 may be a commonly used metal.

[0025] (Rolling elements) The material constituting the rolling elements 40 may be any commonly used material, and examples of such materials include steel and ceramics. Since ceramics are not metals, the use of ceramics as the material constituting the rolling elements 40 prevents rust from occurring due to corrosion.

[0026] (Metal parts) The metal member 31 may be made of a metal. Examples of the metal include iron, brass, an aluminum alloy, and a magnesium alloy. Among them, an aluminum alloy or a magnesium alloy is preferable. When the metal member 31 includes an aluminum alloy or a magnesium alloy, the cage 30 is made lighter. In this case, the cage 30 is less likely to deform due to centrifugal force when the rolling bearing 100 is used. Therefore, the positional deviation of the rolling elements 40 caused by the deformation of the housing portion 32 of the cage 30 is suppressed. In addition, the cage 30 and the raceway members 10 and 20 are less likely to come into contact with each other, and the increase in the rotational resistance of the rolling bearing 100 and the collision noise and seizure caused by the collision between the cage 30 and the raceway members 10 and 20 can be suppressed. Furthermore, the weight of the cage 30 is reduced, and the weight of the rolling bearing 100 is also reduced, so that the initial rotation loss torque of the rolling bearing 100 can be reduced, and the energy required to rotate the rolling bearing 100 can be reduced. Furthermore, since aluminum alloys and magnesium alloys have low density, vibrations are easily attenuated, so that the cage 30 can quickly attenuate any generated noise.

[0027] It is particularly preferred that the metal is an aluminum alloy. Since an aluminum alloy has a higher Young's modulus than a magnesium alloy, even if a centrifugal force is applied to the cage 30 during use of the rolling bearing 100, distortion is unlikely to occur, and deformation of the housing portion 32 is suppressed. Therefore, displacement of the rolling elements 40 due to deformation of the housing portion 32 of the cage 30 is further suppressed.

[0028] The aluminum alloy is an alloy containing aluminum as a main component. Examples of such aluminum alloys that can be used include Al-Si-Cu aluminum alloys such as ADC12, Al-Si-Mg aluminum alloys such as AC4C and DX-30, Al-Si-Cu aluminum alloys such as ADC10 and A380, Al-Si-Mn-Mg alloys such as Silafont and NA-6, and A383 such as AlSi9Cu3(Fe), AlSi9MnMg, and ADC12.

[0029] Magnesium alloys are alloys whose main component is magnesium. Examples of such magnesium alloys include Mg-Al-Zn-Mn based alloys such as AZ91D, Mg-Al-Mn based alloys such as AM60B, and Mg-Al-Si-Mn based alloys such as AS41A.

[0030] The defect rate in the metal member 31 may be 0.020% by volume or more. The defect rate is the volume ratio of defects 33 in the metal member 31. The defects 33 refer to spaces formed in the metal member 31, and are also called voids. The defects can be imaged using an X-ray CT scanner (manufactured by Carl Zeiss, "ZEISS METROTOM1500") under the following imaging conditions: <Imaging conditions> X200 (Voxel: 26.43 μm) Number of projections: 1500 Tube voltage: 170kV Tube current: 140μA Integration time: 2000ms Sensitivity: 16X Image averaging: OFF Detection point mode: 1×1 In the CT image obtained by imaging, a defect is a part that appears black against the white part that corresponds to the metal component.

[0031] The defect rate is calculated as follows: (1) Using VG studio MAX Version 3.5 as defect analysis software, open the original CT file (file with the extension ".vgi") from the CT scan image and define the surface. Specifically, if the horizontal axis of the CT image is the gray value (shade value) and the vertical axis is the number of occurrences, the surface located midway between the surface passing through the maximum value of the peaks in the background (black side) and the surface passing through the maximum value of the peaks in the TP (matrix, white side) is automatically set as the defined surface (surface of the product). In this case, the gray value of the defined surface is the average value of the gray value of the maximum value of the peaks in the background and the gray value of the maximum value of the peaks in the TP. (2) Next, perform defect analysis using "Defect / Inclusion Analysis (VGdefX / Threshold Only)" and calculate the total defect volume. In the property window for "Defect / Inclusion Analysis (VGdefX / Threshold Only)", check "Result Filter" and set the minimum size of the "General Filter" to "8 Voxel" so that countless noises are not displayed as defects. Other "Defectivity" that is thought to affect the defect rate is set to the default (standard) value of "1". (3) For the total defect volume calculated in (2), calculate the defect rate (volume %) based on the product volume (100 volume %). The defect rate in the metal member 31 may be 0.050 vol % or more, 0.075 vol % or more, 0.100 vol % or more, 0.150 vol % or more, or 0.200 vol % or more. The defect rate in the metal member 31 is preferably 4.756 vol% or less. The defect rate in the metal member 31 may be 4 vol% or less, 3 vol% or less, 2 vol% or less, or 1 vol% or less. By making the defect rate in the metal member 31 4.756 vol% or less, it is possible to suppress a decrease in the mechanical strength of the metal member 31.

[0032] (Storage section) The accommodation portion 32 is a through hole, and the shape of the inner wall surface varies depending on the shape of the rolling element 40. When the rolling element 40 is a sphere as shown in Fig. 1, the shape of the inner wall surface is a cylindrical surface.

[0033] (Surface protective layer) As already described, the retainer 30 may or may not further have a surface protective layer that protects the surface of the metal member 31, but it is preferable that the retainer 30 has the surface protective layer. By the retainer 30 further having the surface protective layer, the retainer 30 is less likely to affect the quietness of the rolling bearing using the retainer 30 during use, and the wear resistance of the rolling bearing using the retainer 30 can be improved. The surface protective layer is preferably provided at a portion of the surface of the metal member 31 that may come into contact with the metal member 31. For example, when the metal member 31 comes into contact with the rolling element 40, the surface protective layer preferably covers at least the inner wall surface of the housing portion 32. When the metal member 31 comes into contact with the raceway members 10, 20, the surface protective layer is preferably provided at a portion of the surface of the metal member 31 that will come into contact with the raceway members 10, 20. The surface protective layer may be provided so as to cover the entire surface of the metal member 31.

[0034] Examples of the surface protective layer include a film obtained by anodizing, hard anodizing, fluororesin coating, etc. Among these, when the metal member 31 contains an aluminum alloy, the surface protective layer is preferably a film obtained by anodizing the metal member 31 from the viewpoint of further improving the wear resistance.

[0035] Furthermore, the thickness of the surface protective layer is not particularly limited, but is preferably 3 μm to 35 μm, more preferably 5 μm to 30 μm, and particularly preferably 10 μm to 25 μm. In particular, when the thickness of the surface protective layer is 3 μm or more, the wear resistance during use of a rolling bearing using the retainer 30 is further improved. Furthermore, when the thickness of the surface protective layer is 35 μm or less, the surface protective layer is less likely to fall off during use of a rolling bearing using the retainer 30.

[0036] (Manufacturing method) The cage 30 can be manufactured by using an injection molding method such as die casting. Specifically, the cage 30 can be manufactured by applying a liquid-containing release agent to a mold cavity formed by a mold attached to a fixed platen and a movable platen, injecting molten metal to fill the cavity, and removing the mold after cooling. At this time, the defect rate in the metal member 31 can be adjusted by, for example, applying an excessive amount of release agent or by the amount of air blowing performed after application and before the molten metal is injected into the mold. If the amount of release agent applied is large or the release agent is intentionally applied to a place where the liquid is likely to remain in the mold, the liquid that comes into contact with the molten metal will vaporize and remain in the product as a cavity, thereby increasing the defect rate. If the amount of air blowing is small, the possibility that the solvent in the release agent will remain in the mold before the molten metal is injected into the mold is high, so the defect rate can be increased. On the other hand, if the amount of air blowing is large, or if the air blowing can be sprayed at an appropriate position even if the amount of air blowing is not large, the solvent in the release agent can be blown out of the mold when the molten metal is injected into the mold, so the defect rate can be reduced. Alternatively, the defect rate can be reduced by suctioning the air from within the cavity to create a near vacuum just before the molten metal is injected into the mold. As the release agent, for example, inorganic substances such as graphite and mica, and organic substances such as oil and wax dispersed in water can be used. When the cage 30 further has a surface protective layer, the surface protective layer may be provided on the metal member 31. In this case, as described above, the surface protective layer can be obtained by anodizing, hard anodizing, or fluororesin coating.

[0037] The present disclosure is not limited to the above-described embodiment. For example, in the above-described embodiment, a thrust ball bearing is shown as the rolling bearing, but the rolling bearing may be a radial bearing. Examples of the radial bearing include a deep groove ball bearing, a cylindrical roller bearing, a tapered roller bearing, a spherical roller bearing, a needle roller bearing, and an angular contact ball bearing.

[0038] The outline of this disclosure is as follows. [1] A retainer for holding a plurality of rolling elements in a rolling bearing having a plurality of rolling elements and a pair of raceway members sandwiching the rolling elements, the retainer comprising a metal member containing defects, the metal member having an accommodation portion for accommodating the rolling elements, and a defect rate, which is the volumetric percentage of the defects in the metal member, of 0.020 volume % or more. [2] The cage according to [1], wherein the defect rate in the metal member is 4.756 volume % or less. [3] The cage according to [1] or [2], wherein the metal member comprises an aluminum alloy or a magnesium alloy. [4] The cage according to [1] or [2], wherein the metal member comprises an aluminum alloy. [5] The cage according to any one of [1] to [4], wherein the rolling bearing is a thrust ball bearing. [6] The cage according to any one of [1] to [5], further comprising a surface protection layer for protecting a surface of the metal member. [7] The cage according to [6], wherein the surface protective layer is an oxide film obtained by anodizing the metal member. [8] The cage according to [6] or [7], wherein the surface protective layer has a thickness of 10 μm to 25 μm. [9] A rolling bearing comprising a plurality of rolling elements, a retainer that holds the plurality of rolling elements, and a pair of raceway members that sandwich the rolling elements, the retainer being the retainer described in any one of [1] to [8]. [Explanation of symbols]

[0039] 10... raceway member, 20... raceway member, 30... cage, 31... metal member, 32... accommodation portion, 33... defect, 40... rolling element, 100... bearing.

Claims

1. A cage for holding a plurality of rolling elements in a rolling bearing including a pair of raceway members sandwiching the rolling elements, the cage comprising: A metal member having a defect is provided, the metal member has an accommodating portion that accommodates the rolling element, A cage, wherein a defect rate, which is a volume ratio of the defects in the metal member, is 0.020 volume % or more.

2. The cage according to claim 1 , wherein the defect rate in the metal member is 4.756 volume percent or less.

3. The cage of claim 1 , wherein the metal member comprises an aluminum alloy or a magnesium alloy.

4. The cage of claim 1 , wherein the metallic member comprises an aluminum alloy.

5. 2. The cage according to claim 1, wherein the rolling bearing is a thrust ball bearing.

6. The cage according to claim 1 , further comprising a surface protection layer for protecting a surface of the metal member.

7. 7. The cage according to claim 6, wherein the surface protective layer is an oxide film obtained by subjecting the metal member to an anodizing treatment.

8. The cage according to claim 6, wherein the surface protective layer has a thickness of 10 μm to 25 μm.

9. A plurality of rolling elements; a cage for holding the plurality of rolling elements; A pair of raceway members sandwiching the rolling elements therebetween, A rolling bearing, wherein the cage is the cage according to any one of claims 1 to 8.

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