Method for manufacturing raceway ring component, method for manufacturing rolling bearing, method for manufacturing hub unit bearing, and method for manufacturing vehicle

Abstract

After the centerless grinding process, a finishing process is performed. In the centerless grinding process, the inner ring (3) is rotated relative to the grinding stone in a specified direction, and the grinding stone is pressed against the sliding contact surface (10) of the inner ring (3), thereby grinding the sliding contact surface (10). In the finishing process, a process is performed to form a grinding texture on the sliding contact surface (10) in a direction intersecting with the grinding texture formed on the sliding contact surface (10) in the centerless grinding process, and / or to improve the surface roughness of the sliding contact surface (10).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing raceway ring components such as an inner ring and an outer ring constituting a rolling bearing and a hub constituting a hub unit bearing.

[0002] This application claims priority based on Japanese Patent Application No. 2019-015850, filed on January 31, 2019, the contents of which are incorporated herein by reference. Background Art

[0003] Rolling bearings such as ball bearings, roller bearings, and tapered roller bearings are assembled in the rotating support parts of various mechanical devices. The rolling bearing has: an outer ring having an outer ring raceway on the inner circumference; an inner ring having an inner ring raceway on the outer circumference; and a plurality of rolling elements arranged to roll freely between the outer ring raceway and the inner ring raceway. In addition, the rolling bearing is provided with a sealing device to prevent the grease sealed in the internal space provided with the rolling elements from leaking to the outside, and to prevent foreign matter such as rainwater, mud, and dust from entering the internal space. The sealing device has at least one sealing lip, the top end of which is in sliding contact with the sliding contact surface formed on the inner ring over the entire outer circumference.

[0004] In order to suppress the sliding torque of the top end of the sealing lip relative to the sliding contact surface to be small when the outer ring and the inner ring rotate relative to each other, grinding is performed on the portion of the inner ring that at least includes the sliding contact surface. As a method for performing grinding on the portion of the inner ring that at least includes the sliding contact surface, for example, the centerless grinding method described in Japanese Patent Publication No. 2001-138186 can be adopted. That is, in a state where the inner ring is supported from below by a workpiece holder, the inner ring is rotated by pressing a rotating adjustment wheel against the outer peripheral surface of the inner ring, and at the same time, a rotating grindstone is pressed against the outer peripheral surface of the inner ring from a side substantially opposite to the adjustment wheel in the radial direction, thereby performing grinding on the outer peripheral surface of the inner ring.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2001-138186 Summary of the invention

[0008] When the outer peripheral surface of the inner ring is subjected to grinding processing using a grindstone, the abrasive grains in the grindstone come into contact with the outer peripheral surface of the inner ring as the grindstone rotates relative to the inner ring. As the grindstone rotates relative to the inner ring, the abrasive grains are pressed against the outer peripheral surface of the inner ring while moving in the circumferential direction. Thus, the metal present on the outer peripheral surface of the inner ring is removed by the abrasive grains. Then, as the grindstone rotates relative to the inner ring, the abrasive grains are separated from the outer peripheral surface of the inner ring. Therefore, if grinding processing is performed by pressing a rotating grindstone having a certain degree of hardness against the outer peripheral surface of the inner ring while the inner ring is rotated relative to the grindstone in a predetermined direction, deformations such as ridges and burrs will occur on both sides of the portion where the abrasive grains pass. Such deformation has a tendency (directionality) in the circumferential direction. Therefore, if the deformed portion is used as the sliding contact surface with which the tip of the seal lip slides, there is a possibility that the difference in sliding torque of the tip of the seal lip relative to the sliding contact surface between the first relative rotation direction and the second relative rotation direction of the outer ring and the inner ring, that is, the difference in rotation torque of the inner ring relative to the outer ring (the difference in rotation torque between forward rotation and reverse rotation) becomes greatly different. Specifically, if the outer ring is fixed, there is a possibility that the sliding torque of the tip of the seal lip relative to the sliding contact surface differs (a difference in sliding torque is generated) between the case where the inner ring is rotated in a predetermined direction (first relative rotation) and the case where the inner ring is rotated in a direction opposite to the predetermined direction (second relative rotation). The reason for this is considered to be that the sliding torque of the tip of the seal lip relative to the sliding contact surface differs depending on whether the sliding direction of the tip of the seal lip relative to the sliding contact surface is the same as the moving direction of the grindstone relative to the inner ring when the inner ring is ground by the grindstone.

[0009] The present invention aims to realize a method for manufacturing a raceway component having high rotation characteristics, which raceway component can, for example, suppress the difference in sliding torque of the tip of a seal lip relative to a sliding contact surface caused by the relative rotation direction of a pair of raceway components.

[0010] One aspect of the method for manufacturing a raceway ring component of the present invention is that the raceway ring component has a sliding contact surface over the entire outer circumference with which the top end portion of the sealing lip slides, and in order to manufacture the raceway ring component, a finishing step is performed after a centerless grinding step.

[0011] In the centerless grinding step, the raceway member is rotated relative to the grindstone in a predetermined direction, and the grindstone is pressed against the sliding contact surface, thereby grinding the sliding contact surface.

[0012] In the finishing step, processing is performed to form a plurality of grinding textures in irregular directions on the sliding contact surface and / or to increase the surface roughness of the sliding contact surface.

[0013] The finishing step can be performed by subjecting the sliding contact surface to a lapping process using a lapping brush containing abrasive grains, a nonwoven fabric abrasive material, or a lapping tape (wrapping film), a grinding process using an elastic grindstone, or a super finishing process.

[0014] One aspect of a method for manufacturing a rolling bearing of the present invention is directed to a rolling bearing having:

[0015] The first raceway ring component;

[0016] A second raceway ring component having a sliding contact surface on the entire outer circumference and arranged coaxially with the first raceway ring component;

[0017] a plurality of rolling elements rotatably disposed between the first raceway member and the second raceway member; and

[0018] The sealing device has at least one sealing lip that allows the top end portion to be in sliding contact with the sliding contact surface.

[0019] In one aspect of the method for manufacturing a rolling bearing of the present invention, the second raceway component is manufactured by the method for manufacturing a raceway component of the present invention.

[0020] One of the first raceway ring component and the second raceway ring component can be set as an outer ring, and the other of the first raceway ring component and the second raceway ring component can be set as an inner ring coaxially arranged on the inner diameter side of the outer ring. Preferably, the first raceway ring component is set as an outer ring, and the second raceway ring component is set as an inner ring. However, the first raceway ring component can also be set as an inner ring, and the second raceway ring component can be set as an outer ring.

[0021] One aspect of a method for manufacturing a hub unit bearing of the present invention is directed to a hub unit bearing having:

[0022] An outer diameter side raceway ring component has a plurality of rows of outer ring raceways on the inner circumference;

[0023] An inner diameter side raceway ring component has a sliding contact surface on the surface over the entire outer circumference and has a plurality of rows of inner raceways on the outer circumference;

[0024] A plurality of rolling elements are disposed between the plurality of rows of outer ring raceways and the plurality of rows of inner ring raceways so as to be able to roll freely; and

[0025] A sealing device having at least one sealing lip for making the top end portion slide in contact with the sliding contact surface,

[0026] One of the outer diameter side raceway member and the inner diameter side raceway member is a fixed side raceway member supported and fixed with respect to the suspension device.

[0027] The other of the outer diameter side raceway member and the inner diameter side raceway member is a rotating side raceway member that rotates together with the wheel and the brake rotor.

[0028] In one embodiment of the method for manufacturing a hub unit bearing of the present invention, the inner diameter side raceway component is manufactured by the method for manufacturing a raceway component of the present invention.

[0029] One embodiment of a method for manufacturing a vehicle according to the present invention is directed to a vehicle having a hub unit bearing, and the hub unit bearing is manufactured by the method for manufacturing a hub unit bearing according to the present invention.

[0030] One embodiment of the present invention is a method for manufacturing a rolling bearing, which utilizes centerless grinding, wherein the rolling bearing has an inner ring, an outer ring, a plurality of rolling elements, a sealing lip, and a sliding contact surface provided on the inner ring or the outer ring and for the top end of the sealing lip to slide in contact with, the method comprising the following contents: pressing a grindstone to a portion of the inner ring or the outer ring that includes the sliding contact surface and simultaneously performing centerless grinding on the sliding contact surface; and performing processing on the sliding contact surface to eliminate the directionality of surface roughness generated on the sliding contact surface due to the centerless grinding.

[0031] One embodiment of the present invention is a method for manufacturing a rolling bearing, which utilizes centerless grinding, wherein the rolling bearing has an outer ring, a plurality of rolling elements, a sealing lip, and a sliding contact surface provided on the outer ring or the hub and for the top end of the sealing lip to slide in contact with, the method comprising the following contents: pressing a grindstone against a portion of the outer ring or the hub that includes the sliding contact surface and simultaneously performing centerless grinding on the sliding contact surface; and performing processing on the sliding contact surface to eliminate the directionality of surface roughness generated on the sliding contact surface due to the centerless grinding.

[0032] Effects of the Invention

[0033] According to the above-described aspects of the present invention, a raceway component having high rotational characteristics can be provided, which can, for example, suppress the difference in sliding torque of the tip of the seal lip relative to the sliding contact surface caused by the relative rotational direction of a pair of raceway components. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1It is a cross-sectional view showing a rolling bearing serving as a target of a first example of an embodiment of the present invention.

[0035] Figure 2 This is a side view showing a state in which a centerless grinding process is performed in the first example of the embodiment of the present invention.

[0036] Figure 3 This is a cross-sectional view showing a state in which a finishing step is performed in the first example of the embodiment of the present invention.

[0037] Figure 4 This is a cross-sectional view showing another example of how the finishing step is performed in the first example of the embodiment of the present invention.

[0038] Figure 5 It is a cross-sectional view showing a hub unit bearing that is a target of a second example of an embodiment of the present invention.

[0039] Figure 6 yes Figure 5 Magnified view of the X section.

[0040] Figure 7 This is a side view showing a state in which a centerless grinding process is performed in the second example of the embodiment of the present invention.

[0041] Figure 8 This is a cross-sectional view showing a state in which a finishing step is performed in the second example of the embodiment of the present invention.

[0042] Fig. 9 This is a cross-sectional view showing another example of how the finishing step is performed in the second example of the embodiment of the present invention.

[0043] Fig.10 is a partial schematic diagram of a vehicle having a hub unit bearing (bearing unit). DETAILED DESCRIPTION

[0044] [First example of implementation]

[0045] pass Figures 1 to 4 A first example of an embodiment of the present invention will be described. Figure 1 The rolling bearing 1 used as the object of this example is shown. The rolling bearing 1 has an outer ring 2 as a first raceway member, an inner ring 3 as a second raceway member, a plurality of rolling elements 4, and a pair of sealing devices (seal rings) 5.

[0046] The outer ring 2 is made of a hard iron alloy such as bearing steel and carburizing steel, and has an outer ring raceway 6 with a circular arc cross-section on the inner circumference of the axial center part, and has locking grooves 7 that are recessed radially outward on the inner circumference of the axial side parts.

[0047] The inner ring 3 is made of a hard iron alloy such as bearing steel or carburizing steel, and is coaxially arranged on the inner diameter side of the outer ring 2. The inner ring 3 has an inner ring raceway 8 with a circular cross-section on the outer peripheral surface of the axial center portion throughout the entire circumference, and has a sealing groove 9 recessed radially inward on the outer peripheral surface of the axial side portions throughout the entire circumference. In addition, the inner ring 3 has a circular sliding contact surface 10 on the side surfaces facing opposite directions (axially outward) in the inner surface of each sealing groove 9 throughout the entire circumference. In this example, the sliding contact surface 10 has multiple grinding textures formed in irregular directions, and / or the arithmetic mean roughness Ra of the sliding contact surface 10 is less than 0.1μm.

[0048] In the rolling bearing 1 , the axially inner side refers to the center side in the width direction of the rolling bearing 1 , and the axially outer side refers to the outer sides (both sides) in the width direction of the rolling bearing 1 .

[0049] Each rolling element 4 is made of an iron alloy such as bearing steel or ceramics, and is disposed between the outer ring raceway 6 and the inner ring raceway 8 in a rollable state while being held by a cage 11. In this example, balls are used as the rolling elements 4.

[0050] Each sealing device 5 seals the openings on both sides of the axial direction of the internal space 12 in which the rolling element 4 is arranged, prevents the grease sealed in the internal space 12 from leaking to the outside, and prevents foreign matter such as rainwater, mud, and dust from entering the internal space 12. Each sealing device 5 has a ring-shaped core material 13, and an elastic material 14 made of an elastomer such as rubber reinforced by the core material 13. Each sealing device 5 can be manufactured by arranging the core material 13 in the cavity of the mold and then injection molding the material constituting the elastic material 14 into the core material 13. As the material constituting the elastic material 14, for example, nitrile rubber, acrylic rubber, silicone rubber, fluororubber, ethylene propylene rubber, hydrogenated nitrile rubber, etc. can be used.

[0051] The core material 13 is formed by bending a metal plate such as a mild steel plate to have a substantially L-shaped cross-section and is formed into an annular shape as a whole. That is, the core material 13 has a cylindrical portion 15 and a circular portion 16 bent at a right angle from the axially outer end of the cylindrical portion 15 toward the radially inner side.

[0052] The elastic material 14 includes an elastic locking portion 17 at the radially outer end, a thin-walled annular covering portion 18 covering the entire circumference of the axially outer side of the annular portion 16, and a sealing portion 19 at the radially inner end.

[0053] In the free state before the elastic locking portion 17 is locked with the locking groove 7 of the outer ring 2, the elastic locking portion 17 has a width dimension slightly larger than the width dimension (axial dimension) of the locking groove 7, covering the outer peripheral surface and the top end surface (axial inner end surface) of the cylindrical portion 15 of the core material 13.

[0054] The sealing portion 19 has a sealing lip 20 , a grease lip 21 , and a dust protection lip 22 .

[0055] The seal lip 20 is formed to be located radially inward of the radially inner end of the annular portion 16 of the core member 13 and to protrude axially inward, and its tip end is in sliding contact with the sliding contact surface 10 of the seal groove 9 over the entire circumference.

[0056] The grease lip 21 has a substantially triangular cross-sectional shape and is formed so as to protrude axially inward from a portion of the seal portion 19 that is located radially outward relative to the seal lip 20. The grease lip 21 has its tip end close to the connection portion between the inner ring raceway 8 and the seal groove 9 in the outer peripheral surface relative to the inner ring 3, so that a labyrinth seal is formed between this portion and the tip end of the grease lip 21.

[0057] The dust-proof lip 22 has a substantially rectangular cross-sectional shape and is formed so as to extend radially inward from the radially inner end of the circular cover portion 18. The dust-proof lip 22 has a tip portion close to a portion of the inner ring 3 that is axially outward relative to the seal groove 9, so that a labyrinth seal is formed between the tip portion of the dust-proof lip 22 and the tip portion of the dust-proof lip 22.

[0058] The elastic locking portion 17 is arranged (locked) on the inner side of the locking groove 7 in a state of elastic compression in the axial and radial directions, whereby each sealing device 5 is supported relative to the outer ring 2 and the top end portion of the sealing lip 20 is in sliding contact with the sliding contact surface 10 of the sealing groove 9 over the entire circumference with a surplus.

[0059] When manufacturing the inner ring 3 constituting the rolling bearing 1 , first, a metal material is subjected to plastic working such as forging and cutting to form the outer shape of the inner ring 3 .

[0060] The subsequent centerless grinding process can be performed using, for example, Figure 2 The grinding wheel 24 is provided with a grinding stone 23, an adjusting wheel 25, a workpiece holder 26 and a grinding fluid nozzle 27. In the centerless grinding process, the inner ring 3 is rotated in one direction while the grinding stone 23 is pressed against a portion of the outer peripheral surface of the inner ring 3 including the sliding contact surface 10, thereby grinding the outer peripheral surface of the inner ring 3.

[0061] The grindstone 23 is a rotating grindstone that is disc-shaped and has a generatrix shape that matches the generatrix shape of the outer peripheral surface of the inner ring 3 and rotates around a central axis (not shown). For example, the grindstone 23 may be a grindstone in which A (alumina) type abrasive grains are bonded by a glass type binder, and has a bond size of #60 to #400, a bond degree of G to O, a concentration of 4 to 12, and a porosity of 20% to 50%.

[0062] The regulating wheel 25 can be driven to rotate around a central axis inclined at a predetermined angle relative to the central axis of the grindstone 23. The grinding disc 24 shown in the figure also has a cleaning device 28 for removing foreign matter such as grinding chips attached to the outer peripheral surface of the regulating wheel 25 during grinding.

[0063] The workpiece support 26 is disposed below a portion between the grindstone 23 and the adjustment wheel 25 and supports the inner ring 3 from below.

[0064] The grinding fluid nozzle 27 is disposed above a portion between the grindstone 23 and the regulating wheel 25 such that a discharge port of the grinding fluid faces downward.

[0065] When the centerless grinding process is performed using the grinding disk 24, first, the inner ring 3 as the workpiece is placed between the upper surface of the workpiece holder 26 and the outer peripheral surface of the adjustment wheel 25. Then, the grinding liquid is sprayed toward the outer peripheral surface of the inner ring 3 from the grinding liquid nozzle 27. And, by rotating the adjustment wheel 25, the inner ring 3 is rotated in one direction (counterclockwise in the example shown in the figure), and the grindstone 23 rotating about its own central axis is pressed against the portion of the outer peripheral surface of the inner ring 3 including the sliding contact surface 10, thereby performing grinding on the portion. In addition, in this case, by making the circumferential speed of the inner ring 3 and the circumferential speed of the grindstone 23 different from each other, the inner ring 3 is rotated relative to the grindstone 23 in a predetermined direction (one direction).

[0066] In this way, in the centerless grinding process, the inner ring 3 is relatively rotated in a predetermined direction with respect to the grindstone 23, and the hard grindstone 23 is pressed against the outer peripheral surface of the inner ring 3, thereby performing the grinding process. Therefore, there is a possibility that deformations such as ridges and burrs may occur on both sides of the portion where the abrasive grains of the grindstone 23 pass through in the sliding contact surface 10 of the inner ring 3 obtained by the centerless grinding process.

[0067] In the subsequent finishing process, the sliding contact surface is subjected to processing to eliminate the directionality of the surface roughness generated on the sliding contact surface 10 due to centerless grinding. For example, in the finishing process, processing is performed to form a plurality of grinding textures in irregular directions on the sliding contact surface 10 and / or to improve the surface roughness of the sliding contact surface 10. The directionality of the surface roughness is caused based on the relative movement direction of the sliding contact surface 10 relative to the grindstone 23 in the centerless grinding. In the case of improving the surface roughness of the sliding contact surface 10, specifically, the arithmetic mean roughness Ra of the sliding contact surface 10 is set to be less than 0.1 μm. In addition, by forming a plurality of grinding textures in irregular directions on the sliding contact surface 10, the surface roughness of the sliding contact surface 10 can also be improved.

[0068] The finishing process can be performed, for example, Figure 3 The elastic grindstone 29 is used as shown. The elastic grindstone 29 is disc-shaped and has a generatrix shape that matches the generatrix shape of the sealing groove 9. In addition, the elastic grindstone 29 has more pores and is softer (has appropriate elasticity) than the grindstone 23 used in the centerless grinding process. As the elastic grindstone 29, for example, a grindstone obtained by bonding A (alumina) abrasive grains with a resin adhesive, with a bonded particle size of #600 to #1200, a bond degree of F to T, a concentration of 6 to 14, a porosity of 40% to 80%, and softer than the grindstone 23 used in the centerless grinding process can be used.

[0069] When the elastic grindstone 29 is used for the finishing process, the inner ring 3 is rotated about the central axis of the inner ring 3. Then, the surface of the radially outer side of the elastic grindstone 29 rotating about its own central axis is pressed against each seal groove 9 of the inner ring 3, thereby grinding the inner surface of each seal groove 9 including the sliding contact surface 10, thereby improving the surface roughness of the sliding contact surface 10. In other words, the unevenness caused by the ridges and burrs formed in the centerless grinding process is reduced.

[0070] Alternatively, you can use Figure 4 As the abrasive-containing polishing brush 30, for example, a wire-made polishing brush having moderate elasticity and having a particle size of #80 to #600 A (alumina) or GC (green silicon carbide) abrasive grains mixed in nylon fibers such as nylon 6 can be used.

[0071] When the finishing process is performed using the grinding brush 30 containing abrasive grains, the inner ring 3 is rotated about the central axis of the inner ring 3 while the grinding brush 30 containing abrasive grains is pressed against each seal groove 9 of the inner ring 3. Thus, the inner surface of each seal groove 9 including the sliding contact surface 10 is ground, and a plurality of grinding textures in irregular directions are formed on the sliding contact surface 10.

[0072] The finishing process is not limited to the method using the elastic grindstone 29 and the grinding brush 30 containing abrasive grains, and is not particularly limited as long as it is possible to form multiple grinding textures in irregular directions on the sliding contact surface 10 and / or improve the surface roughness of the sliding contact surface 10. Specifically, for example, the sliding contact surface 10 can be ground by a non-woven grinding material formed by bonding A (alumina) or GC (green silicon carbide) abrasive grains with a particle size of #80 to #600 to a nylon non-woven fabric, thereby forming multiple grinding textures in irregular directions on the sliding contact surface 10. Alternatively, the sliding contact surface 10 can be ground by a grinding belt (wrapping film) coated with abrasive grains on the surface, or super finishing by pressing a reciprocating grindstone to the sliding contact surface 10 can also improve the surface roughness of the sliding contact surface 10.

[0073] In addition, when the finishing process is performed by any method, the pair of seal grooves 9 may be processed simultaneously, or the pair of seal grooves 9 may be processed separately (in sequence).

[0074] Furthermore, before, during, or simultaneously with the finishing process, the inner ring raceway 8 is subjected to superfinishing for improving the surface roughness of the inner ring raceway 8, or heat treatment such as quenching is performed at an appropriate time as required, thereby completing the inner ring 3. Furthermore, the rolling bearing 1 is obtained by combining the inner ring 3 with the outer ring 2, the rolling elements 4, the pair of sealing devices 5, and the cage 11. For example, a conventionally known method can be applied to a method for manufacturing the outer ring 2, the rolling elements 4, the pair of sealing devices 5, and the cage 11, and a method for assembling the rolling bearing 1.

[0075] In this example, a finishing step is performed after the centerless grinding step, thereby forming a plurality of grinding textures in irregular directions on the sliding contact surface 10 and / or improving the surface roughness of the sliding contact surface 10. Therefore, according to this example, compared with a structure in which only the centerless grinding process is performed, the difference in the sliding torque of the tip portion of the seal lip 20 with respect to the sliding contact surface 10 between the relative rotation of the inner ring 3 with respect to the outer ring 2 in the first direction and the relative rotation in the second direction opposite to the first direction can be suppressed to be small.

[0076] That is, when a plurality of grinding textures in irregular directions are formed on the sliding contact surface 10 in the finishing process, the concavo-convex shape of the sliding contact surface 10 becomes complicated, and it is difficult for the tip of the seal lip 20 to enter the concave portion. The directionality of the surface roughness generated on the sliding contact surface 10 due to centerless grinding is eliminated. As a result, the difference in the sliding torque of the tip of the seal lip 20 with respect to the sliding contact surface 10 generated based on the relative rotation direction of the inner ring 3 with respect to the outer ring 2 can be reduced.

[0077] In contrast, when the surface roughness of the sliding contact surface 10 is increased in the finishing process, that is, when the unevenness of the sliding contact surface 10 is reduced, the influence of deformation caused by the ridges and burrs formed in the centerless grinding process on the tip of the seal lip 20 during the relative rotation of the inner ring 3 with respect to the outer ring 2 is reduced. The directionality of the surface roughness generated on the sliding contact surface 10 due to the centerless grinding is eliminated. As a result, the difference in the sliding torque of the tip of the seal lip 20 with respect to the sliding contact surface 10 generated based on the relative rotation direction of the inner ring 3 with respect to the outer ring 2 can be reduced. The rolling bearing in which the directionality of the surface roughness generated on the sliding contact surface 10 is eliminated has high rotation characteristics and is preferably suitable for use as a rotating component used under both forward and reverse rotation conditions.

[0078] In addition, although the manufacturing method of the rolling bearing of this example is for a rolling bearing (ball bearing) 1 using balls as rolling elements 4, the manufacturing method of the rolling bearing of the present invention can also be for needle bearings, cylindrical roller bearings, and tapered roller bearings. In addition, the present invention is not limited to single-row rolling bearings, but can also be for multi-row rolling bearings including multiple rows, and can also be for a structure in which the top end of the sealing lip constituting the sealing device is in sliding contact with the sliding contact surface of the outer ring. Furthermore, the present invention is not limited to radial rolling bearings, but can also be for thrust rolling bearings as long as they have a sealing device.

[0079] [Second example of implementation]

[0080] pass Figures 5 to 9 The second example of the embodiment of the present invention is described below. This example is directed to a hub unit bearing that supports a wheel and a brake rotating body rotatably relative to a suspension device of a vehicle. Figure 5 As shown, the hub unit bearing 31 is formed by rotatably supporting a hub 33 as an inner diameter side raceway component and a rotating side raceway component on the inner side of an outer ring 32 as an outer diameter side raceway component and a fixed side raceway component via a plurality of rolling elements 34a and 34b.

[0081] The outer ring 32 is made of hard metal such as medium carbon steel, and has multiple rows of outer ring raceways 35a, 35b, and a stationary flange 36. Multiple rows of outer ring raceways 35a, 35b are formed on the inner circumferential surface of the axial middle portion of the outer ring 32 over the entire circumference. The stationary flange 36 is formed in the axial middle portion of the outer ring 32 so as to protrude radially outward, and has support holes 37 that are threaded holes at multiple locations in the circumferential direction of the radial middle portion. The outer ring 32 is supported and fixed relative to the knuckle 38 by screwing and fastening bolts 40 that pass through through holes 39 formed on the knuckle 38 constituting the suspension device of the vehicle into the support holes 37 of the stationary flange 36 from the axial inside.

[0082] In addition, regarding the hub unit bearing 31, the axial inner side refers to the side that becomes the center side of the vehicle body when the hub unit bearing 31 is assembled to the vehicle. Figure 5 as well as Figure 6 On the other hand, the axially outer side refers to the side that becomes the outer side of the vehicle body when the hub unit bearing 31 is assembled to the vehicle. Figure 5 as well as Figure 6 on the left side.

[0083] The hub 33 is coaxially arranged on the inner diameter side of the outer ring 32 and has multiple rows of inner ring raceways 41a, 41b and a rotating flange 42. The multiple rows of inner ring raceways 41a, 41b are formed in the outer peripheral surface of the hub 33 in the entire circumference, respectively, at the portion facing the multiple rows of outer ring raceways 35a, 35b. The rotating flange 42 is formed in the hub 33 in a manner protruding radially outward at the portion located axially outward compared to the axially outward end of the outer ring 32, and has mounting holes 43 penetrating in the axial direction at multiple locations in the radial middle portion. In this example, in order to connect and fix a braking rotating body 44 such as a brake disc and a brake drum to the rotating flange 42, the serration portion formed on the portion near the base end of the stud 45 is pressed into the mounting hole 43, and the middle portion of the stud 45 is inserted into the through hole 46 formed in the braking rotating body. Furthermore, in order to fix the wheel 47 constituting the wheel to the rotating flange 42, the convex thread portion formed at the top end of the stud 45 is inserted into the through hole 48 formed in the wheel 47, and then screwed and fastened with the convex thread portion via the nut 49. In addition, since the hub unit bearing 31 of this example is for the driving wheel, the center portion of the hub 33 has an engaging hole 61 for engaging with a driving shaft (not shown).

[0084] In this example, a hub body 50 made of hard metal such as medium carbon steel and having an inner ring raceway 41a on the axial outer side and an inner ring 51 made of hard metal such as bearing steel and having an inner ring raceway 41b on the axial inner side are joined and fixed to each other, thereby constituting the hub 33. Specifically, in a state where the inner ring 51 is externally fitted to the axial inner portion of the hub body 50, the axial inner end surface of the inner ring 51 is pressed by a caulking portion 53 formed by plastically deforming the axial inner end of a cylindrical portion 52 existing at the axial inner end of the hub body 50 toward the radial outer side, thereby joining and fixing the hub body 50 and the inner ring 51. The hub 33 of this example has a sliding contact surface 54 over the entire circumference, from the radial inner end of the axial inner side surface of the rotating flange 42 to the portion of the outer circumferential surface existing at the axial outer side of the inner ring raceway 41a on the axial outer side. The sliding contact surface 54 has a plurality of grinding textures formed in irregular directions, and / or has an arithmetic mean roughness Ra of 0.1 μm or less.

[0085] The rolling elements 34a and 34b are made of hard metal such as bearing steel or ceramic, and are formed in plurality between the multi-row outer ring raceways 35a and 35b and the multi-row inner ring raceways 41a and 41b, and are arranged to roll freely while being held by retainers 55a and 55b. With such a configuration, the hub 33 is rotatably supported on the inner diameter side of the outer ring 32. In this example, balls are used as the rolling elements 34a and 34b.

[0086] Furthermore, in the hub unit bearing 31 of this example, the axially inner opening of the internal space 56 in which the rolling elements 34a and 34b are arranged is sealed by the combined seal ring 57, and the axially outer opening of the internal space 56 is sealed by the sealing device 58. Thus, the grease sealed in the internal space 56 is prevented from leaking to the outside, and foreign matter such as rainwater, mud, and dust is prevented from entering the internal space 56.

[0087] The combined seal ring 57 is formed by sliding contact between the top end of a plurality of seal lips of a seal ring 60 embedded and fixed at the end axially inside the outer ring 32 and an oil slinger 59 embedded and fixed at the end axially inside the hub 33.

[0088] The sealing device 58 includes an annular core member 62 and an elastic material 63 made of an elastic body such as rubber and reinforced by the core member 62 .

[0089] The core material 62 is formed by bending a metal plate such as a mild steel plate to have a substantially L-shaped cross-sectional shape, and is formed into a circular ring shape as a whole. That is, the core material 62 has a cylindrical fitting tube portion 64 that is embedded and fixed to the axially outer end of the outer ring 32, and a bent portion 65 that is bent from the axially outer end of the fitting tube portion 64 toward the radial inner side.

[0090] The elastic material 63 has a base 66 and a plurality of (three in the illustrated example) sealing lips 67. The base 66 is fixed to the bent portion 65 of the core material 62 by vulcanization bonding in such a manner as to cover the axially outer side surface and the radially inner end of the bent portion 65. The sealing lips 67 extend from the base 66 toward the sliding contact surface 54 of the hub 33, respectively, so that the top end portion is in sliding contact with the sliding contact surface 54 over the entire circumference.

[0091] In this example, when manufacturing the hub body 50 constituting the hub 33 of the hub unit bearing 31 , first, a metal material is subjected to forging, cutting, and the like to shape the outer shape of the hub body 50 .

[0092] In the subsequent centerless grinding process, Figure 7As shown, the hub body 50 is rotated relative to the grindstone 68 in a predetermined direction, and the grindstone 68 is pressed against a portion of the outer peripheral surface of the hub body 50 including the sliding contact surface 54 , thereby grinding the outer peripheral surface of the hub body 50 .

[0093] The grindstone 68 of this example is a so-called shaped rotating grindstone having a generatrix shape that matches the generatrix shape in the range from the sliding contact surface 54 to the axial inner end of the cylindrical portion 52 on the outer peripheral surface of the hub body 50. As the grindstone 68, for example, a grindstone in which A (alumina) type abrasive grains are bonded by a glass type binder, with a bond size of #60 to #400, a bond degree of G to O, a concentration of 4 to 12, and a porosity of 20% to 50% can be used.

[0094] When the grinding stone 68 is used for the centerless grinding process, first, the magnetic chuck 69 is coupled to the axial outer side surface of the rotating flange 42 by magnetic attraction. The hub body 50 is rotated by rotating the magnetic chuck 69. Figure 6 The bearing bush 70 (only one is shown in the figure) supports the outer peripheral surface of the axial middle portion of the hub body 50, thereby achieving radial positioning of the hub body 50. In addition, the grinding stone 68 as a forming rotating grinding stone is rotated about its own central axis O 68 The grinding stone 68 rotates around the center, while pressing the outer peripheral surface of the grinding stone 68 against the portion of the outer peripheral surface of the hub body 50 including the sliding contact surface 54, thereby grinding the portion. In addition, the grinding stone 68 is appropriately trimmed to a shape that matches the generatrix shape of the hub body 50 after the centerless grinding process is completed by the forming rotary dresser 71. In addition, it is possible that deformations such as bulges and burrs are generated on both sides of the portion of the sliding contact surface 54 of the hub body 50 obtained by the centerless grinding process, through which the abrasive grains in the grinding stone 68 pass.

[0095] In the subsequent finishing process, the sliding contact surface 54 is subjected to processing to eliminate the directionality of the surface roughness generated on the sliding contact surface 54 by centerless grinding. For example, processing is performed to form a plurality of grinding textures in irregular directions on the sliding contact surface 54 and / or to increase the surface roughness of the sliding contact surface 54.

[0096] For example Figure 8As shown, the finishing process can be performed by superfinishing the sliding contact surface 54 of the hub body 50. When superfinishing, the hub body 50 is pushed in the axial direction by the pressure roller 72, and the axially outer end of the hub body 50 is pressed against the pad 73, and the pad 73 is rotated, thereby rotating the hub body 50. In addition, the arm 74 of the superfinishing disk 81 is reciprocated around the swing shaft 75 arranged at a position twisted relative to the central axis of the hub body 50, thereby reciprocating (oscillating; oscillation) the superfinishing grindstone 76 supported on the top end of the arm 74, and the arm 74 is displaced in the axial direction by the conveying mechanism 77, so that the superfinishing grindstone 76 is pressed against the sliding contact surface 54. In this way, the sliding contact surface 54 of the hub body 50 is superfinished, thereby improving the surface roughness of the sliding contact surface 54. In other words, the unevenness caused by deformation such as ridges and burrs formed in the centerless grinding process is reduced.

[0097] In addition, as the superfinishing grindstone 76, specifically, for example, a grindstone obtained by bonding A (alumina) or GC (green silicon carbide) abrasive grains with a glass-based adhesive, a bonded grain size of #1000 to #8000, and a RH (Rockwell hardness H scale) of -120 to 40 can be used.

[0098] Or, if Fig. 9 As shown, the finishing process can also be performed using a polishing tape (wrapping film) 78 coated with abrasive grains on the surface. The polishing tape 78 is formed by applying abrasive grains such as alumina white or green corundum, diamond, etc. with a bonding particle size of #1000 to #8000 to a thickness of 5 μm to 10 μm roughly uniformly on the surface of a polyester film with a thickness of 25 μm to 75 μm using an adhesive.

[0099] When the finishing process is performed using the grinding tape 78, the hub body 50 is centered about the center axis O of the hub body 50. 50 And, while the grinding belt 78 is pressed to the sliding contact surface 54 by the vibration head 79, multiple ( Fig. 9 The roller 80 (only two are shown) conveys the grinding belt 78 along the sliding contact surface 54 from the axial outer side to the axial inner side, thereby performing belt grinding on the sliding contact surface 54. As a result, the surface roughness of the sliding contact surface 54 is improved. In other words, the unevenness caused by deformation such as ridges and burrs formed in the centerless grinding process is reduced.

[0100] However, the finishing process is not limited to super finishing and belt grinding. Other processing methods that can form a plurality of grinding textures in irregular directions on the sliding contact surface 54 and / or can improve the surface roughness of the sliding contact surface 54 can be used. Specifically, for example, the sliding contact surface 54 is ground or polished by an elastic grindstone having moderate elasticity, a grinding brush containing abrasive grains, or a non-woven fabric grinding material, thereby enabling the finishing process to be performed.

[0101] Moreover, before, during, or at the same time as the finishing process, the inner ring raceway 41a on the axial outer side is subjected to superfinishing, or heat treatment such as quenching is performed at an appropriate time as required, thereby completing the hub body 50. Then, the hub body 50 is combined with the outer ring 32, the rolling elements 34a, 34b, the retaining frames 55a, 55b, the inner ring 51, the combined seal ring 57, and the sealing device 58, thereby obtaining the hub unit bearing 31. For example, a conventionally known method can be applied to a method for manufacturing the outer ring 32, the rolling elements 34a, 34b, the retaining frames 55a, 55b, the inner ring 51, the combined seal ring 57, and the sealing device 58, and a method for assembling the hub unit bearing 31.

[0102] In this example, after the centerless grinding process, the finishing process is performed, thereby forming a plurality of grinding textures in irregular directions on the sliding contact surface 54 and / or improving the surface roughness of the sliding contact surface 54. Therefore, according to this example, the difference in the sliding torque of the tip of the seal lip 67 with respect to the sliding contact surface 54 between the relative rotation of the hub 33 in the first direction with respect to the outer ring 32 and the relative rotation in the second direction opposite to the first direction can be suppressed to be small. The configuration and effects of other parts are the same as those of the first example of the embodiment.

[0103] In addition, although the manufacturing method of the hub unit bearing of this example is for the hub unit bearing 31 using balls as rolling elements 34a and 34b, the manufacturing method of the hub unit bearing of the present invention can also be for the hub unit bearing using tapered rollers as rolling elements. In addition, the manufacturing method of the hub unit bearing of the present invention is not limited to the hub unit bearing for the driving wheel having an engagement hole for engaging the driving shaft in the center of the hub, but can also be for the hub unit bearing for the driven wheel having a solid hub. Moreover, the manufacturing method of the hub unit bearing of the present invention is not limited to the hub unit bearing of the inner ring rotating type, and as long as it has a sealing device, it can also be for the outer ring rotating type hub unit bearing in which the outer diameter side raceway ring component is set as the rotating side raceway ring component and the inner diameter side raceway ring component is set as the fixed side raceway ring component.

[0104] Fig.101 is a partial schematic diagram of a vehicle 200 having a hub unit bearing (bearing unit) 151. The present invention can be applied to any of a hub unit bearing for a driving wheel and a hub unit bearing for a driven wheel. Fig.10 In the embodiment, the hub unit bearing 151 is for driving wheels and has an outer ring 152, a hub 153 and a plurality of rolling elements 156. The outer ring 152 is fixed to the knuckle 201 of the suspension device using bolts or the like. The wheel (and the rotating body for braking) 202 is fixed to the flange (rotating flange) 153A provided on the hub 153 using bolts or the like. In addition, the vehicle 200 can have the same support structure as described above for the hub unit bearing 151 for the driven wheels.

[0105] Description of Reference Numerals

[0106] 1 Rolling bearings

[0107] 2 Outer ring

[0108] 3 Inner ring

[0109] 4 Rolling elements

[0110] 5 Sealing device

[0111] 6 Outer ring raceway

[0112] 7 Locking groove

[0113] 8 Inner ring raceway

[0114] 9 Sealing groove

[0115] 10 Sliding contact surface

[0116] 11 Cage

[0117] 12. Internal Space

[0118] 13 core material

[0119] 14 Elastic materials

[0120] 15 Cylinder

[0121] 16 Circle

[0122] 17 Elastic locking part

[0123] 18 Circle Cover

[0124] 19 Sealing part

[0125] 20 Sealing lip

[0126] 21 Grease lip

[0127] 22 Anti-dust lip

[0128] 23 Grindstone

[0129] 24 Grinding disc

[0130] 25 Adjustment wheel

[0131] 26 Workpiece rack

[0132] 27 Grinding fluid nozzle

[0133] 28. Cleaning device

[0134] 29 Elastic grinding stone

[0135] 30 Abrasive brush with abrasive grains

[0136] 31 Hub unit bearing

[0137] 32 Outer ring

[0138] 33 Wheels

[0139] 34a, 34b rolling element

[0140] 35a, 35b Outer ring raceway

[0141] 36 Stationary flange

[0142] 37 Support hole

[0143] 38 Steering knuckle

[0144] 39 Through Holes

[0145] 40 Bolts

[0146] 41a, 41b Inner ring raceway

[0147] 42 Swivel flange

[0148] 43 Mounting holes

[0149] 44 Braking rotating body

[0150] 45 studs

[0151] 46 Through Holes

[0152] 47 Wheels

[0153] 48 Through Holes

[0154] 49 Nut

[0155] 50 Hub body

[0156] 51 Inner Circle

[0157] 52 Cylinder

[0158] 53 Riveting Department

[0159] 54 Sliding contact surface

[0160] 55a, 55b cage

[0161] 56 Interior Space

[0162] 57 Combined sealing ring

[0163] 58 Sealing device

[0164] 59 Oil slinger

[0165] 60 Sealing ring

[0166] 61 snap-in hole

[0167] 62 core material

[0168] 63 Elastic material

[0169] 64 fitting cylinder

[0170] 65 Folding

[0171] 66 base

[0172] 67 Sealing lip

[0173] 68 Grindstone

[0174] 69 Magnetic chuck

[0175] 70 Bearing

[0176] 71 Rotary Dresser

[0177] 72 Pressure roller

[0178] 73 Pad

[0179] 74 Arm

[0180] 75 Swing shaft

[0181] 76 Superfinishing Grinding Stone

[0182] 77 Conveying mechanism

[0183] 78 Abrasive belt

[0184] 79 Vibration Head

[0185] 80 Roller

[0186] 81 Super finishing disc.

Claims

1. A method for manufacturing a rolling bearing, the method utilizing centerless grinding, the method being characterized in that: The rolling bearing comprises an inner ring, an outer ring, a plurality of rolling elements, a sealing lip, and a sliding contact surface provided on the inner ring or the outer ring and with which the top end of the sealing lip makes sliding contact. The method includes the following contents: centerlessly grinding the sliding contact surface while pressing a grindstone to a portion of the inner ring or the outer ring including the sliding contact surface; and a finishing step of performing processing on the sliding contact surface after the centerless grinding to eliminate the directionality of the surface roughness on the sliding contact surface caused by the grindstone in contact with the sliding contact surface during the centerless grinding, The finishing process does not perform super finishing of pressing the super finishing grindstone to the sliding contact surface while reciprocating the super finishing grindstone, but includes grinding using a grinding brush containing abrasive particles, a non-woven fabric grinding material or a grinding belt to form a plurality of grinding textures in irregular directions on the sliding contact surface in a manner that makes the concave-convex shape of the sliding contact surface having the directionality of the surface roughness complex.

2. The method for manufacturing a rolling bearing according to claim 1, characterized in that: The directionality of the surface roughness is generated based on a relative moving direction of the sliding contact surface with respect to the grindstone during the centerless grinding.

3. A method for manufacturing a raceway ring component, the raceway ring component having a sliding contact surface with which the top end of a sealing lip slides over the entire periphery, the method for manufacturing the raceway ring component being characterized by: The method includes the following contents: a centerless grinding step in which the raceway ring component is rotated relative to a grindstone in a predetermined direction while the grindstone is pressed against the sliding contact surface, thereby grinding the sliding contact surface; and a finishing step of performing processing on the sliding contact surface after the centerless grinding to eliminate the directionality of the surface roughness on the sliding contact surface caused by the grindstone in contact with the sliding contact surface during the centerless grinding, In this finishing process, super finishing of pressing the super finishing grindstone to the sliding contact surface while reciprocating the super finishing grindstone is not performed, and a plurality of grinding textures in irregular directions are formed on the sliding contact surface in such a manner that the concave-convex shape of the sliding contact surface having the directionality of the surface roughness becomes complex, using a grinding brush containing abrasive grains, a non-woven fabric grinding material or a grinding belt.

4. The method for manufacturing a raceway ring component according to claim 3, characterized in that: The finishing step further includes performing processing on the sliding contact surface to increase the surface roughness.

5. A method for manufacturing a rolling bearing, the rolling bearing comprising: The first raceway ring component; A second raceway member having a sliding contact surface over the entire periphery of the surface and arranged coaxially with the first raceway member; a plurality of rolling elements rotatably disposed between the first raceway member and the second raceway member; and A sealing device having at least one sealing lip for making the top end portion slide in contact with the sliding contact surface, The method for manufacturing a rolling bearing is characterized in that: The second raceway component is manufactured by the raceway component manufacturing method according to claim 3 or 4.

6. The method for manufacturing a rolling bearing according to claim 5, characterized in that: One of the first raceway member and the second raceway member is an outer ring, The other of the first raceway member and the second raceway member is an inner ring disposed coaxially with the outer ring and on the inner diameter side of the outer ring.

7. A method for manufacturing a hub unit bearing, the method utilizing centerless grinding, characterized in that: The hub unit bearing comprises an outer ring, a hub, a plurality of rolling elements, a sealing lip, and a sliding contact surface provided on the outer ring or the hub and with which the top end of the sealing lip slides. The method includes the following contents: Pressing a grindstone to a portion of the outer ring or the hub including the sliding contact surface while centerlessly grinding the sliding contact surface; and a finishing step of performing processing on the sliding contact surface after the centerless grinding to eliminate the directionality of the surface roughness on the sliding contact surface caused by the grindstone in contact with the sliding contact surface during the centerless grinding, The finishing process does not perform super finishing of pressing the super finishing grindstone to the sliding contact surface while reciprocating the super finishing grindstone, but includes grinding using a grinding brush containing abrasive particles, a non-woven fabric grinding material or a grinding belt to form a plurality of grinding textures in irregular directions on the sliding contact surface in a manner that makes the concave-convex shape of the sliding contact surface having the directionality of the surface roughness complex.

8. A method for manufacturing a hub unit bearing, the hub unit bearing comprising: An outer diameter side raceway ring component has multiple rows of outer ring raceways on the inner circumference; An inner diameter side raceway ring component has a sliding contact surface over the entire outer circumference of the surface and has a plurality of rows of inner raceways on the outer circumference; A plurality of rolling elements are disposed between the plurality of rows of outer ring raceways and the plurality of rows of inner ring raceways so as to be able to roll freely; and A sealing device having at least one sealing lip for making the top end portion slide in contact with the sliding contact surface, One of the outer diameter side raceway member and the inner diameter side raceway member is a fixed side raceway member supported and fixed with respect to the suspension device. The other of the outer diameter side raceway member and the inner diameter side raceway member is a rotating side raceway member that rotates together with the wheel and the brake rotor, and the method for manufacturing the hub unit bearing is characterized in that: The inner diameter side raceway component is manufactured by the raceway component manufacturing method according to claim 3 or 4.

9. A method for manufacturing a vehicle having a wheel hub unit bearing, wherein: The hub unit bearing is manufactured by the method for manufacturing a hub unit bearing according to claim 8 .

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