JP2010058576A - Bearing device for wheels - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device for wheels, capable of increasing the hardness of the outer peripheral surface of the shaft part of a hub being a part desired for strength and fatigue strength under high stress and cyclic stress in a limited manner, and capable of suppressing the degradation of productivity caused by an increase in the number of manufacturing steps. <P>SOLUTION: An internal member 1 includes: a hub 14 having a flange for mounting wheels 17; and a part having an orbital surface to be fit or combined with the shaft part 14a of the hub 14. In the hub 14, a parent material part has a standard structure formed through hot forging process from a steel material and the outer peripheral surface of the shaft part 14a has a part 30 formed in a non-standard structure. The non-standard structure is obtained by laser hardening. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bearing device for a wheel that has been improved in strength for passenger cars, freight cars, and the like.

In the wheel bearing device, there is a portion where the stress increases when the automobile turns sharply. For example, the shaft portion near the base portion of the hub wheel mounting flange of the hub is stressed when the vehicle turns suddenly. Further, in a hub of a type in which the hub is provided independently of the bearing portion and the inner ring of the bearing is fitted to the outer periphery, the inner ring abutting surface that is formed near the root of the wheel mounting flange and the inner ring end face abuts on Corners between the outer peripheral surfaces of the shaft portions show high stress when the vehicle turns sharply.
In order to improve the fatigue strength, there are a method of performing high-frequency heat treatment near the base of the flange or the like (for example, Patent Document 1) and a method of performing shot peening (the processing location is different, for example, Patent Document 2). ).

In the above-described high-frequency heat treatment, the deflection accuracy of the flange may be deteriorated due to thermal strain or the like. In addition, depending on the shape, high-frequency heat treatment may cause a problem that a part of the component becomes locally too hot and melts, and may not be employed depending on the shape of the part to be treated.
In shot peening, media accumulates on the surface of the processing location according to the processing, so that the media does not reach the processing location surface, and media removal may be required to perform multiple processing.
In order to increase the fatigue strength, there is a method of tempering the entire part and increasing the hardness (for example, Patent Document 3). However, the entire workability (for example, machinability and cooling such as caulking) is improved by increasing the hardness. Inter-workability) may decrease, and slip torque may decrease due to a decrease in the biting property of the hub bolt.

Accordingly, the present inventors cooled a part of the hub (the seal contact surface on the outboard side, the inner ring fitting surface, etc.) that is red hot with a refrigerant during the hot forging process of the hub or at the end of the process. And the method of obtaining the non-standard structure | tissue which becomes hardness-intensity in the part by carrying out self-recuperation and recuperation holding | maintenance tempering is proposed (for example, patent documents 4 and 5).
JP 11-051064 A JP-A-2005-239100 JP-A-2005-003061 JP 2007-038803 A JP 2007-051748 A

  However, in the case of the techniques disclosed in Patent Documents 4 and 5 that use forging heat, the refrigerant reaches the part other than the part that is desired to be a non-standard structure, so that an undesired part is hardened and shaved by a later turning process. Problems such as difficulty. For example, in the tests by the present inventors, a part of the wheel mounting flange on which the refrigerant was scattered hardened to 30 to 35 HRC, and the life of the turning blade was sometimes reduced.

  The object of the present invention is to increase the hardness of the outer peripheral surface of the shaft portion of the hub, which is a portion where sufficient strength and fatigue strength are desired against high stress and repeated stress, and to increase the number of processes. It is an object of the present invention to provide a wheel bearing device capable of suppressing a decrease in productivity.

A wheel bearing device according to a first aspect of the present invention includes an inner member and an outer member that are rotatable with respect to each other via a double row of rolling elements, and the inner member includes a wheel mounting flange. And a bearing device for a wheel including a component having a raceway surface that is fitted or coupled to the shaft portion of the hub,
The base material portion of the hub is a standard structure obtained by hot forging of a steel material, and has a non-standard structure portion on the outer peripheral surface of the shaft portion, and the non-standard structure is obtained by laser quenching. It is.

  When the vehicle turns, for example, a large-amplitude flexure is repeatedly generated in the wheel mounting flange, and high stress is repeatedly generated in a portion such as a seal contact surface near the base of the flange. The portion of the seal contact surface is an outer peripheral surface portion between the raceway surface of the hub and the wheel mounting flange, which is in sliding contact with the seal on the outboard side attached to the outboard side end of the outer member. When the outer peripheral surface portion of the hub shaft is the non-standard structure, the strength and fatigue strength are improved due to the refinement of the structure and the increased hardness, and cracks occur in the outer peripheral surface of the hub shaft. Is suppressed. Therefore, the displacement of the wheel mounting flange can be suppressed. That is, the effect of crack generation → increased displacement of the wheel mounting flange → increase in vehicle vibration → damage of the wheel bearing device is suppressed, and the life is extended. By having a non-standard structure portion on the outer peripheral surface of the shaft portion in this way, the strength and fatigue strength of the wheel bearing device are improved, thereby reducing the input weight of product production of the wheel bearing device. Thus, the cost can be reduced and it can be provided at a low cost. Further, since the wheel bearing device is light, the weight of the automobile can be reduced, and the fuel consumption can be improved.

  Since the portion of the non-standard structure is obtained by laser quenching in particular, only the outer peripheral surface of the shaft portion of the hub can be heat-treated by limiting by laser quenching, so that the deflection accuracy of the wheel mounting flange can be improved. High accuracy can be maintained. In addition, an unintended place is not hardened due to scattering of the refrigerant. When the non-standard structure portion is limited to the outer peripheral surface of the shaft portion of the hub, the workability such as machinability and caulking properties is different from the case where the entire hub surface is non-standard structure. Is minimized. Therefore, most of the entire hub other than the outer peripheral surface of the shaft portion is not cured, and grinding processing after the heat treatment can be easily and quickly performed. Therefore, the number of processing steps can be reduced and the cycle time per product can be improved as compared with the conventional one. In other words, it is possible to suppress a decrease in productivity due to an increase in the number of processes compared to the conventional one. In addition, the life of a grinding wheel or the like can be extended, and the manufacturing cost can be reduced.

The inner member has a raceway surface in each of the hub and the component fitted or coupled to the shaft portion of the hub, and a seal that seals between the inner member and the outer member, The non-standard structure portion of the hub is mounted on the outboard side end of the outer member and slidably contacts the seal contact surface which is the outer peripheral surface portion between the hub raceway surface and the wheel mounting flange. The part used as a contact surface may be sufficient.
In this case, cracks are suppressed from occurring near the seal contact surface of the shaft portion of the hub. Since the seal contact surface has a non-standard structure and the hardness is increased, wear due to sliding contact with the seal is also reduced. Therefore, the sealability of the seal on the outboard side in particular can be improved, and entry of foreign matter and muddy water can be prevented.

A wheel bearing device according to a second aspect of the present invention includes a bearing in which rolling elements are interposed in a double row between an inner ring and an outer ring, a shaft portion for fitting the inner ring of the bearing to the outer periphery, and a wheel mounting flange. In a wheel bearing device in which the end surface of the inner ring on the outboard side abuts on the inner ring abutting surface extending from the end on the wheel mounting flange side of the outer peripheral surface of the shaft portion of the hub to the outer diameter side,
The base material portion of the hub is a standard structure obtained by hot forging of a steel material, and includes a corner R portion with an inner ring contact surface from at least the vicinity of the inner ring contact surface on the outer peripheral surface of the shaft portion. A non-standard tissue portion is included in a range extending over the shaft portion, and the non-standard tissue is a tissue obtained by laser quenching.

  Due to turning of the automobile, a large amplitude flexure is repeatedly generated in the wheel mounting flange, and high stress is repeatedly generated at the corner between the inner ring contact surface and the outer peripheral surface of the hub which is the root portion of the flange. . According to the configuration of the wheel bearing device of the second invention, since the corner between the inner ring contact surface and the outer peripheral surface of the hub is the non-standard structure with respect to such repeated high stress, the structure The refinement and hardness increase improve the strength and fatigue strength and suppress the occurrence of cracks. That is, the effect of crack generation → increase in displacement of the stress generation site → increase in vehicle vibration → damage of the wheel bearing device is suppressed, thereby extending the life.

The portion of the non-standard structure has a fine structure and a hardness equal to or higher than that of a base material portion made of a standard structure. This refinement and increased hardness improves the fatigue strength of the non-standard structure part, and can withstand higher stress amplitude, that is, higher strength and longer life compared to a hub consisting only of a normal standard structure. Can be Therefore, it can be reduced in size and weight as compared with a wheel bearing device having a normal standard structure. Therefore, the input weight for manufacturing the wheel bearing device can be reduced, the cost can be reduced, and it can be provided at a low cost. Further, since the wheel bearing device is light, the weight of the automobile can be reduced, and the fuel consumption can be improved.
Furthermore, since the hardness of the non-standard structure is higher than that of the standard structure, wear on the inner ring contact surface of the hub is reduced, and creep due to wear is suppressed. For this reason, the wear of the inner ring contact surface due to creep → axial force reduction, further creep generation → shaft wear → cracking from edge-shaped wear ends → durability degradation is suppressed.

  In the second invention, the portion of the non-standard structure may be provided up to a location where the inner ring on the inboard side on the outer peripheral surface of the shaft portion is fitted. By providing a non-standard tissue portion over a wide range of the shaft portion, the strength and fatigue strength of the shaft portion are further improved. Therefore, it is possible to further reduce the size and weight of the wheel bearing device, and it is possible to further reduce the input weight of manufacturing the wheel bearing device.

  In the second aspect of the invention, the inner ring is fixed to the hub in the axial direction by pressing the end face of the inner ring by a crimped portion obtained by crimping the inboard side end of the shaft portion of the hub to the outer diameter side, The outer peripheral surface near the inboard side end of the shaft portion may be a part of the same standard structure as the base material. When the vicinity of the inboard side end is a non-standard structure, it is difficult to process the crimped portion, but by using the standard structure, it is possible to prevent the workability of the crimping process from being lowered.

The non-standard structure, which is a structure obtained by laser quenching, is one of a fine ferrite / pearlite structure, an upper bainite structure, a lower bainite structure, a tempered martensite structure, or at least two of these structures It may be a mixed tissue.
Any of the above-mentioned fine ferrite / pearlite structure, upper bainite structure, lower bainite structure, tempered martensite structure, or at least a non-standard structure such as a mixed structure of two or more of these structures is standard. Compared with the base material portion made of the structure, the structure is fine and the hardness is equal to or higher than that. This refinement and increased hardness improves the fatigue strength of the non-standard structure part, and can withstand higher stress amplitude, that is, higher strength and longer life compared to a hub consisting only of a normal standard structure. Can be Therefore, it can be reduced in size and weight as compared with a wheel bearing device having a normal standard structure. Further, since the wheel bearing device is light, the weight of the automobile can be reduced, and the fuel consumption can be improved.

The hardness of the part of the non-standard structure may be 20 HRC or more and 40 HRC or less, and the hardness of the base material part may be 13 HRC or more and 25 HRC or less. When the hardness of the portion of the non-standard structure is 20 HRC or more and 40 HRC or less, the toughness is excellent. In this case, the hardness of the non-standard structure is set to 20 HRC or more and 40 HRC or less by high temperature tempering.
The hardness of the non-standard structure portion may be 40 HRC or more, and the hardness of the base material portion may be 13 HRC or more and 25 HRC or less. When the hardness of the non-standard structure is 40 HRC or more, strength such as rigidity and fatigue strength can be improved.

  When the hardness of the non-standard structure is less than 20 HRC, the strength and fatigue strength are insufficient, and the toughness is excellent in the range of 20 HRC or more and 40 HRC or less. Is inferior. The lower limit of the hardness of the non-standard structure portion is preferably 20 HRC or more, preferably 25 HRC or more, which is about the center value of the base material hardness, in order to improve fatigue strength by increasing the hardness. The material used for the hub is carbon steel (C amount 0.4 to 0.8 wt%), but in the case of S53C or the like, the hardness of the standard structure portion is 13 to 25 HRC. In the case of performing cold working such as caulking, or considering the portion where the hub bolt is press-fitted, it is preferable that the maximum is 25 HRC.

  The depth of the non-standard tissue is preferably 0.1 mm or more and 1.5 mm or less. When the depth of the non-standard tissue is less than 0.1 mm, the non-standard tissue is too thin and the effect cannot be expected. In addition, if the depth of the non-standard tissue is larger than 1.5 mm, the laser irradiation time becomes long to obtain a deep non-standard tissue, so that the part other than the irradiation range is heated and the irradiation range is not easily cooled after irradiation. Problems such as a decrease in hardness, deterioration of the structure, and deterioration of accuracy such as vibration of the wheel mounting flange are likely to occur.

The non-standard structure which is a structure obtained by laser quenching may be a structure obtained by quenching using YAG laser light. According to the YAG laser beam, the wavelength of the laser beam can be shortened, the permeability is excellent, and the workpiece can be processed deeply.
Further, the non-standard structure that is a structure obtained by laser quenching may be a structure obtained by quenching using a semiconductor laser beam. Since the semiconductor laser has high energy conversion efficiency, a large-scale cooling mechanism is unnecessary, and a mirror system is not required. Further, since the wavelength of the semiconductor laser light is visible light, there is an advantage that the laser processing is possible even at a low output since the reflectance on the processing surface is low. In addition, since the intensity distribution of the laser beam can be rectangular, large area quenching can be performed efficiently. Therefore, it is possible to further shorten the time required for laser quenching per workpiece, and to reduce the number of man-hours, as compared with the case using the YAG laser beam or the infrared laser beam. In addition, since the laser output can be reduced as compared with YAG laser light or the like, the energy cost can be reduced. In addition, when the non-standard structure is a structure obtained by quenching using a semiconductor laser beam, it is not necessary to apply an absorbent for increasing the absorption of the laser beam to the workpiece, thereby reducing the man-hour. It becomes possible to plan. It is also possible to perform laser hardening using a mirror system together with a semiconductor laser.

A wheel bearing device according to a first aspect of the present invention includes an inner member and an outer member that are rotatable with respect to each other via a double row of rolling elements, and the inner member includes a wheel mounting flange. And a bearing device for a wheel including a component having a raceway surface that is fitted or coupled to the shaft portion of the hub,
The base material portion of the hub is a standard structure obtained by hot forging of a steel material, and has a non-standard structure portion on the outer peripheral surface of the shaft portion, and the non-standard structure is obtained by laser quenching. Therefore, it is possible to increase the hardness of the outer peripheral surface of the hub shaft, which is the part where strength and fatigue strength are desired, against high stress and repeated stress, and to reduce productivity by increasing the number of processes. Is suppressed.

  A wheel bearing device according to a second aspect of the present invention includes a bearing in which rolling elements are interposed in a double row between an inner ring and an outer ring, a shaft portion for fitting the inner ring of the bearing to the outer periphery, and a wheel mounting flange. A wheel bearing device in which an end surface of the inner ring on the outboard side abuts on an inner ring abutting surface extending from an end on the wheel mounting flange side of the outer peripheral surface of the shaft portion of the hub to the outer diameter side, The base material portion of the hub is a standard structure obtained by hot forging, and includes a corner R portion with the inner ring contact surface from at least the vicinity of the inner ring contact surface on the outer peripheral surface of the shaft portion. A hub that has a portion of a non-standard structure in a crossing range, and the non-standard structure is a structure obtained by laser quenching, so that strength and fatigue strength are desired for high stress and repeated stress. The outer peripheral surface of the shaft part of the It can be up, and reduction in productivity due to step up is suppressed

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an example of a wheel bearing device, and this example is applied to support a third generation driven wheel. This wheel bearing device has an inner member 1 and an outer member 2 that are rotatable with respect to each other via a double row of rolling elements 3, and the rolling elements 3 are held by a cage 4 for each row. The term “double row” as used herein refers to two or more rows and may be three or more rows, but in the illustrated example, it is two rows. The inner member 1 and the outer member 2 have double-row raceway surfaces 6 and 7 and raceway surfaces 8 and 9, respectively. This wheel bearing device is a double-row angular contact ball bearing type, the rolling elements 3 are made of balls, and the raceway surfaces 6 and 7 are formed so that the contact angles are outward. Both ends of the bearing space between the inner member 1 and the outer member 2 are sealed with seals 10 and 11.

  The outer member 2 is composed of a single integral part, and a vehicle body mounting flange 12 is provided at an arbitrary position in the width direction. The outer diameter surface portion of the outer member 2 closer to the inboard side than the vehicle body mounting flange 12 is a surface to which a knuckle (not shown) serving as a suspension device of the vehicle body is fitted. In this specification, the side closer to the outside in the vehicle width direction when attached to the vehicle body is referred to as the outboard side (left side in FIG. 1), and the side closer to the center in the vehicle width direction is referred to as the inboard side (see FIG. 1 right side). At a plurality of locations in the circumferential direction of the vehicle body mounting flange 12, vehicle body mounting holes 13 including bolt insertion holes or screw holes are provided. The material of the outer member 2 is, for example, carbon steel having a C content of 0.4 wt% or more and 0.8 wt% or less, such as S53C. However, the steel material used as a raw material is not limited to S53C.

  The inner member 1 is composed of two parts, a hub 14 and an inner ring 15 fitted to the outer periphery of the inboard side end of the shaft portion 14a of the hub 14. The hub 14 and the inner ring 15 are formed with the raceway surfaces 6 and 7 on the inner member 1 side, respectively. An inner ring fitting surface 16 having a step and a small diameter is provided on the inboard side end on the outer periphery of the shaft portion 14a of the hub 14, and the inner ring 15 is press-fitted to the inner ring fitting surface 16 with a squeeze. Match. The inner ring 15 is fixed in the axial direction with respect to the hub 14 by a caulking portion 14b obtained by caulking the inboard side end of the shaft portion 14a of the hub 14 to the outer diameter side. The material of the inner ring 15 is, for example, high carbon chrome bearing steel such as SUJ2. However, the steel material used as a raw material is not limited to SUJ2.

The hub 14 has wheel mounting flanges 17 on the outer periphery of the end of the outboard side of the shaft portion 14a, and hub bolts 19 are inserted into bolt holes 18 provided at a plurality of locations in the circumferential direction of the wheel mounting flanges 17. Is installed in the press-fit state.
An annular pilot portion 20 concentric with the hub 14 protrudes from the base portion of the wheel mounting flange 17 of the hub 14. The pilot portion 20 includes a brake pilot 20a serving as a portion for guiding a brake disc that is attached to the side surface on the outboard side of the wheel mounting flange 17, and a wheel pilot 20b that protrudes further to the outboard side than the brake pilot 20a. Consists of. The pilot unit 20 may be divided into a plurality of portions provided with notches at a plurality of locations in the circumferential direction.

  The hub 14, the inner ring 15, and the outer member 2 are all hot forged products of steel, and among these, as shown in FIG. 2, the surface of the outer periphery of the shaft portion 14a of the hub 14 has a non-standard structure. A portion 30 is provided. Specifically, of the outer peripheral surface of the shaft portion 14 a of the hub 14, a portion that becomes a seal contact surface 41, which is a portion that contacts the seal 10 attached to the outboard side end of the outer member 2, and the inner ring fitting surface 16. Is the non-standard tissue portion 30. The seal contact surface 41 is a portion between the wheel mounting flange 17 and the track surface 6 on the outboard side, and is a non-standard tissue portion 30 across the root of the wheel mounting flange 17. The entire surface of the inner ring fitting surface 16 may be a non-standard tissue portion 30, but the step surface 16a facing the axial direction of the inner ring fitting surface 16 and the peripheral surface portion 16b in the vicinity thereof are non-standard tissue. Part 30.

  The base material portion of the hub 14 has a standard structure. The non-standard structure of the non-standard structure portion 30 is a structure obtained by laser quenching, for example, any one of fine ferrite / pearlite structure, upper bainite structure, lower bainite structure, tempered martensite structure, or at least these. It is assumed that two or more types of mixed tissues are mixed. In each of the following embodiments, the non-standard tissue portion 30 is a tissue obtained by laser hardening even when not specifically described.

The manufacturing process of the hub 14 is performed, for example, in the order of forging → turning → laser quenching → high frequency quenching of the raceway surface → tempering → grinding → assembly.
That is, the material of the hub 14 is made into a forged finished product by hot forging, and the forged finished product is turned. The steel material used as the material is carbon steel having a C content of 0.4 wt% or more and 0.8 wt% or less, such as S53C. However, the steel material used as a raw material is not limited to S53C. The surface on the outer periphery of the shaft portion 14a of the hub 14 subjected to the turning process is hardened by laser hardening.

  As shown in FIG. 3, laser quenching involves quenching and curing the surface layer of a target location by irradiating a location where a high energy laser beam is desired to be cured, and self-quenching after heating. Here, a YAG laser beam is used as the laser beam, and the surface layer on the processed surface is cured without being melted by adjusting its output, defocus amount L1, feed speed, and oscillation mode. As the oscillation form of the laser light, there are a system for continuously oscillating the laser light and a system for intermittently oscillating the laser light. The defocus amount L1 is a value that once focuses the focal point f1 of the condenser lens on the surface S1 of the curing target location, and separates the laser head nozzle LN of the YAG laser oscillator from the surface S1 of the curing target location. In this way, the laser head nozzle LN is separated from the portion to be cured, and the laser light condensed by the lens or the like is irradiated on the surface S1 of the portion to be cured with the focus f1 slightly removed. In this case, the spot diameter of the laser beam on the surface S1 of the portion to be cured becomes larger than when the surface S1 is irradiated with the focal point f1 of the laser beam, and heat is applied substantially uniformly to a relatively wide surface of the portion to be cured. be able to. Therefore, the time required for laser quenching per workpiece can be shortened, and the number of man-hours can be reduced.

  When YAG laser light is used, the wavelength of the laser light can be as short as 1.06 μm, for example, and it has excellent permeability and can be processed deeply. However, the wavelength of the laser beam is not limited to 1.06 μm. Further, the laser beam generated by the YAG laser oscillator may be guided to the laser head nozzle LN by an optical fiber cable (not shown). In this case, it is desirable to arrange the laser head nozzle LN at a predetermined angle α (α is, for example, 5 degrees) with respect to the traveling direction L2. In this case, it is possible to prevent the laser light emitted from the optical fiber cable from being reflected by the metal surface and the reflected light from reentering the optical fiber cable. Therefore, the optical fiber cable can be protected.

  Further, when adjusting the laser beam feeding speed, for example, the laser head nozzle LN may be attached to the tip of a robot arm (not shown). The moving speed can be adjusted by moving the robot arm relative to the portion to be cured. Note that laser hardening may be performed by moving the workpiece relative to the fixed laser head nozzle LN. It is also possible to apply a semiconductor laser as an alternative to the YAG laser. When using a semiconductor laser beam, a laser beam having a wavelength of, for example, 808 nm can be used.

In this laser hardening, in the case where the strength and fatigue strength of the outer peripheral surface of the shaft portion 14a of the hub 14 in the portion that becomes the seal contact surface 41 and the inner ring fitting surface 16 are improved, the hardening range (non-standard tissue portion 30). ) Surface hardness of 40 HRC or more. When toughness is required, it is desirable to perform high-temperature tempering prior to induction hardening of the raceway surface or the like so that the surface hardness in the hardening range is 20 HRC or more and 40 HRC or less. The base material portion of the hub 14 has a standard structure, and the hardness of the base material portion is 13 HRC or more and 25 HRC or less. When the hardness of the non-standard structure is less than 20 HRC, the strength and fatigue strength are insufficient, and the toughness is excellent in the range of 20 HRC or more and 40 HRC or less. Is inferior. When improving strength and fatigue strength, and when toughness is required, the depth of the non-standard structure is desirably 0.1 mm or more and 1.5 mm or less.
Thereafter, induction hardening of the raceway surface 6 and the like is performed and tempered. Thereafter, the raceway surface 6 and the like are ground, and the hub 14 that has been ground is assembled to the wheel bearing device.

  In the manufacturing process of the hub 14, the order of laser hardening and induction hardening may be reversed. In particular, when the distance between the seal contact surface 41 and the wheel mounting flange 17 is short, it is preferable to perform laser hardening after induction hardening of the raceway surface 6 and the like. When the distance between the seal contact surface 41 and the wheel mounting flange 17 is short, the seal contact surface 41 is also deeply quenched when induction hardening is performed. Circumferential runout, radial tilt, etc.) may deteriorate. As countermeasures against this, it is possible to prevent deterioration in accuracy by quenching by laser quenching. However, if laser quenching is first performed on the seal contact surface 41, heat due to induction quenching of the raceway surface 6 performed later is caused by laser quenching. Is tempered at a high temperature, and the hardness of the laser-quenched portion is lowered. Therefore, the hardness of the laser-quenched portion (seal contact surface 41) can be ensured by first performing induction hardening with a wide heat-affected range and then performing laser quenching with a narrow heat-affected range. Tempering is performed by heating with a laser beam whose output, defocus amount, and feed rate are adjusted, whether the hub 14 is put into a heating furnace for overall heating or high-frequency heating. It may be tempered.

According to the wheel bearing device of this configuration, the following effects can be obtained.
Of the shaft portion 14a of the hub 14, the surface portion 30 in the vicinity of the seal contact surface 41 and the inner ring fitting surface 16 is a non-standard structure, and the non-standard structure is a fine ferrite / pearlite structure, an upper bainite structure, a lower bainite structure, Since any one of the tempered martensite structures, or at least a mixed structure of two or more of these structures is used, the strength of the hub shaft portion 14a is improved and a long life is obtained. That is, when the vehicle turns, for example, large-amplitude bending is repeatedly generated in the wheel mounting flange 17, and high stress is repeatedly generated in the vicinity of the root portion of the flange 17 and the corner R portion 16 c of the inner ring fitting surface 16. .

  When the seal contact surface 41 near the root portion of the wheel mounting flange 17 and the surface portion 30 near the inner ring fitting surface 16 are the above-mentioned non-standard texture against such a high stress repeatedly generated, Compared to the base material portion, the structure is fine and the hardness is equal to or higher. That is, any one of the fine ferrite / pearlite structure, the upper bainite structure, the lower bainite structure, and the tempered martensite structure as the non-standard structure, or at least a mixed structure of two or more of these structures is used. The portion 30 of the standard structure has a fine structure and a hardness equal to or higher than that of the base material portion made of the standard structure. By such structure refinement and hardness increase, the strength and fatigue strength of the vicinity of the root portion of the wheel mounting flange 17 and the corner R portion 16c of the inner ring fitting surface 16 which are non-standard structures are improved.

  Therefore, compared with a hub made of only a normal standard structure, it is strengthened and can withstand high stress amplitude, and cracks occur in the vicinity of the root portion of the wheel mounting flange 17 and in the corner R portion 16c of the inner ring fitting surface 16. It is suppressed and the life can be extended. That is, the action of crack generation → increased displacement of the wheel mounting flange 17 → increased vibration of the vehicle → damage of the wheel bearing device is suppressed and the life is extended. In addition, since the seal contact surface 41 has the non-standard structure 30 and the hardness is increased, wear due to sliding contact with the seal is also reduced.

Therefore, it is possible to reduce the size and weight compared to the wheel bearing device of the normal standard structure, and therefore the input weight of the product manufacturing of the wheel bearing device is reduced, the cost can be reduced, and it is provided at a low cost. It becomes possible to do. Further, since the wheel bearing device is light, the weight of the automobile can be reduced, and the fuel consumption can be improved.
Further, the inner ring fitting surface 16 of the hub 14 is a part that easily generates fretting wear by causing minute vibrations in the circumferential direction with respect to the inner ring 15. However, by providing the non-standard tissue portion 30, Fretting wear is suppressed by increasing the hardness and increasing the hardness. As a result, rust, wear powder, galling, and the like are prevented and durability is prevented from being lowered.

  The non-standard tissue portion 30 is obtained in particular by laser quenching. In the present embodiment, when laser quenching the non-standard tissue portion 30, for example, as shown in FIG. 3, the laser head nozzle LN is moved along the curvature of the portion that becomes the seal contact surface 41. In this case, at least one of the output of the laser beam, the defocus amount, and the oscillation mode may be changed. In any case, only the portion of the hub 14 that becomes the seal contact surface 41 and the inner ring fitting surface 16 are laser-quenched in a limited manner, and the portion of the hub 14 that becomes the seal contact surface 41 and the inner ring fitting surface 16. Most of them are not laser hardened. By setting the depth of the non-standard tissue portion 30 in the above-described range, it is possible to prevent deterioration in accuracy of the wheel mounting flange.

  Further, since only the portion of the hub 14 that becomes the seal contact surface 41 and the inner ring fitting surface 16 can be heat-treated by laser quenching, the deflection accuracy of the wheel mounting flange 17 is maintained with high accuracy. It becomes possible. Unlike the case where the surface of the entire hub 14 is a non-standard structure, the machinability of the non-standard structure 30 is limited to a limited range of only the portion serving as the seal contact surface 41 and the inner ring fitting surface 16. Degradation of workability such as crimping and crimping can be minimized. Therefore, most of the hub 14 other than the portion serving as the seal contact surface 41 and the inner ring fitting surface 16 is not cured, and grinding processing after the heat treatment can be easily and quickly performed. Therefore, the number of processing steps can be reduced and the cycle time per product can be improved as compared with the conventional one. In other words, it is possible to suppress a decrease in productivity due to an increase in the number of processes compared to the conventional one. In addition, the life of a grinding wheel or the like can be extended, and the manufacturing cost can be reduced.

Another embodiment of the present invention will be described with reference to the drawings.
In the following description, the same reference numerals are given to portions corresponding to the matters described in the preceding forms in each embodiment, and overlapping description may be omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described in the preceding section. Not only the combination of the parts specifically described in each embodiment, but also the embodiments can be partially combined as long as the combination does not hinder.

FIG. 4 is a sectional view of a wheel bearing device according to a second embodiment of the present invention. FIG. 4 shows the wheel bearing device in the first embodiment shown in FIG. 1 for driving wheels. In the second embodiment, a through hole 21 through which a stem portion (not shown) of the outer ring of the constant velocity joint is inserted is provided at the center of the hub 14. The inner ring 15 is fixed to the hub 14 in the axial direction, without providing the caulking portion 14b in the example of FIG. 1, with the stepped surface of the constant velocity joint outer ring abutting against the width surface of the inner ring 15 and screwed into the end of the stem portion. This is done by tightening a nut (not shown).
In the second embodiment, only the portion of the hub 14 that becomes the seal contact surface 41 is heat-treated by being limited by laser quenching. In this case, the time required for laser quenching per workpiece is reduced as compared with the case where the portion serving as the seal contact surface 41 of the hub 14 and the inner ring fitting surface 16 as in the first embodiment are laser quenched. It becomes possible to reduce the man-hours. Other effects similar to those of the first embodiment are achieved.

  5 to 9 show other embodiments, respectively. Also in each of these embodiments, by providing the non-standard structure portion 30, strength and fatigue strength can be improved by reducing the structure and increasing the hardness, and the life can be extended, or by increasing the hardness, fretting wear, etc. Can be reduced. In each of these embodiments, other than the matters specifically described, the embodiments are the same as those described with reference to FIGS.

  The wheel bearing device of FIG. 5 is of an angular ball bearing type for supporting a driven wheel, and the inner member 1 is a double row in which the inner member 1 is fitted to the outer periphery of the hub 14 and the shaft portion 14 a of the hub 14. It consists of inner rings 15a and 15b. The inner rings 15a and 15b are provided for each row, and the inner ring 15b on the inboard side may have a larger thickness and axial dimension than the inner ring 15a on the outboard side. The inner rings 15 a and 15 b are fixed to the hub 14 in the axial direction by caulking portions 14 b provided on the hub 14. The outer member 2 is composed of one integral part, and the outer diameter surface is a cylindrical surface throughout, and does not have the vehicle body mounting flange 12 in the example of FIG. The material of the outer member 2 of the third embodiment is a high carbon chrome bearing steel such as SUJ2. However, the steel material used as a raw material is not limited to SUJ2.

In this embodiment, the surface of the inner ring fitting surface 16 into which the double rows of inner rings 15 a and 15 b of the hub 14 are fitted is a non-standard tissue portion 30. Although the entire surface of the inner ring fitting surface 16 may be a non-standard tissue portion 30, in this example, the stepped surface 16a facing the axial direction of the inner ring fitting surface 16 and the outboard side in the vicinity of the cross section 16a. A non-standard tissue portion 30 is provided on the peripheral surface portion into which the inner ring 15a is fitted.
As described above, when the non-standard tissue portion 30 is provided on the surface of the inner ring fitting surface 16, the strength and fatigue strength are improved, and the fretting wear of the hub 14 is high in the hardness of the non-standard tissue portion 30. Can be suppressed.

  FIG. 6 shows the wheel bearing device of the example of FIG. 5 for driving wheel support, and the hub 14 has a through hole 21 in the center. Other configurations are the same as the example of FIG. According to the wheel bearing device of FIG. 6, the same effects as those of FIG. 5 are obtained.

The wheel bearing device in FIG. 7 is a tapered roller bearing type for supporting a driven wheel, and the inner member 1 is a double row in which the inner member 1 is fitted to the outer periphery of the hub 14 and the shaft portion 14a of the hub 14. It consists of inner rings 15a and 15b. The inner rings 15a and 15b are provided for each row. The outer member 2 is composed of a single component and has a vehicle body mounting flange 12.
Also in this embodiment, the non-standard tissue portion 30 is provided on the surface of the inner ring fitting surface 16 into which the double rows of inner rings 15a and 15b of the hub 14 are fitted. The entire surface of the inner ring fitting surface 16 may be a non-standard portion 30. In this example, the inner ring fitting surface 16 has a step surface 16a facing the axial direction and a peripheral surface portion in the vicinity of the step surface 16a. And a non-standard tissue portion 30. Also in this embodiment, the provision of the non-standard tissue portion 30 improves the strength and fatigue strength, and prevents fretting wear.

FIG. 8 shows the wheel bearing device of the example of FIG. 7 for driving wheel support, and the hub 14 has a through hole 21 in the center. Further, the inner rings 15 a and 15 b are fixed to the hub 14 in the axial direction by a constant velocity joint (not shown) without depending on the caulking portion 14 b of the hub 14. Other configurations are the same as those in the example of FIG. According to the configuration of the wheel bearing device of FIG. 8, the same effects as those of FIG. 7 are obtained.
In each example of FIGS. 7 and 8, an angular ball bearing type may be used instead of the tapered roller bearing type.

The wheel bearing device of FIG. 9 is of the fourth generation type, and the inner member 1 is composed of a hub 14 and a joint outer ring 32 which is one joint member of the constant velocity joint 31. The raceway surfaces 6 and 7 of each row are formed on the joint outer ring 32. The hub 14 is fitted to the outer periphery of the hollow stem portion of the joint outer ring 32, and the hub 14 and the joint outer ring 32 are coupled to each other by expanding the diameter of the stem portion. The outer member 2 is made of one component and has a vehicle body mounting flange 12.
In this embodiment, the portion that becomes the seal contact surface 41 on the outboard side on the outer peripheral surface of the hub 14 is a non-standard tissue portion 30.
In the case of this embodiment, since the portion that becomes the seal contact surface 41 on the outboard side is the non-standard structure portion 30, the fatigue strength is improved by making the structure finer and increasing the hardness.

Next, an eighth embodiment of the present invention will be described with reference to FIGS.
This wheel bearing device includes a double row bearing BR1 and a hub 14 for fitting the bearing BR1 to the outer periphery. The bearing BR1 is obtained by interposing rolling elements 3 in double rows between inner rings 15a and 15b and an outer ring (outer member) 2. The rolling elements 3 are held by a holder 4 for each row. The term “double row” as used herein refers to two or more rows and may be three or more rows, but in the illustrated example, it is two rows. The rolling element 3 is a tapered roller, but may be a ball. The outer ring 2 is integral and has a vehicle body mounting flange 12 on the outer periphery. At a plurality of locations in the circumferential direction of the vehicle body mounting flange 12, vehicle body mounting holes 13 including bolt insertion holes or screw holes are provided. The inner rings 15a and 15b are provided for each row. Both ends of the bearing space between the inner rings 15 a and 15 b and the outer ring 2 are sealed with seals 10 and 11.

  The hub 14 has a shaft portion 14a for fitting the inner rings 15a and 15b to the outer periphery and a wheel mounting flange 17. The wheel mounting flange 17 is provided with bolt press-fit holes 18 at a plurality of locations in the circumferential direction, and hub bolts 19 are attached to the respective bolt press-fit holes 18 in a press-fit state. A through hole 21 through which a stem portion (not shown) of the outer ring of the constant velocity joint is inserted is provided at the center of the shaft portion 14a. An inner ring contact surface 40 extending toward the outer diameter side is provided at an end of the outer peripheral surface of the shaft portion 14a on the wheel mounting flange side, and the end surface of the inner ring 15a on the outboard side contacts the inner ring contact surface 40. . The inner rings 15a and 15b are fixed to the hub 14 in the axial direction between the inner ring abutment surface 40 by a caulking portion 14b obtained by caulking the inboard side end of the shaft portion 14a of the hub 14 to the outer diameter side. ing. Alternatively, the inner ring 15a, 15b may be fixed by pressing the stepped surface provided on the constant velocity joint outer ring against the width surface of the inner ring 15b on the inboard side without providing the crimping portion 14b.

The hub 14, the inner rings 15a and 15b, and the outer ring 2 are all hot forged products of steel. Among these, the hub 14 has a range extending from the vicinity of at least the inner ring contact surface 40 on the outer peripheral surface of the shaft portion 14a to the shaft portion 14a including the corner R portion 42 with the inner ring contact surface 40. 30.
An inner ring contact surface 40 is formed continuously with the inner ring fitting surface of the shaft portion 14a via the corner R portion 42.
The base material portion of the hub 14 has a standard structure. The axial direction range of the non-standard tissue portion 30 extends to a position where the inner ring 15b on the inboard side is fitted on the outer peripheral surface of the shaft portion 14a, but to a middle portion of the width dimension of the inner ring 15b on the inboard side. The outer peripheral surface closer to the inboard side than this is a part of the same standard structure as the base material. In FIG. 10, the entire inner surface of the inner ring contact surface 40 is a non-standard tissue portion 30. However, when the purpose is to improve the strength and fatigue strength of the hub 14, the inner ring contact surface 40 is the inner ring contact surface 40. Only the peripheral corner R 42 may be a non-standard tissue portion.

In the case of the eighth embodiment, since the corner R portion 42 between the inner ring contact surface 40 and the outer peripheral surface of the hub 14 is the non-standard structure, the strength and fatigue strength are improved by refining the structure and increasing the hardness. And the occurrence of cracks is suppressed. That is, the action of crack generation → increased displacement of the wheel mounting flange 17 → increased vibration of the vehicle → damage of the wheel bearing device is suppressed and the life is extended.
The non-standard tissue portion 30 may be the entire surface of the hub 14, but at least from the vicinity of the inner ring contact surface 40 on the outer peripheral surface of the shaft portion 14 a of the hub 14, a corner with the inner ring contact surface 40 is formed. If only the necessary portion of the range including the R portion 42 and extending to the shaft portion 14a is provided, a decrease in workability such as machinability can be minimized. The non-standard tissue portion 30 is obtained in particular by laser quenching. Therefore, only the non-standard tissue portion 30 can be limited and heat-treated, and the same effects as those of the above embodiments can be obtained.

  Further, since the hardness of the non-standard structure is higher than that of the standard structure, the wear of the inner ring contact surface 40 of the hub 14 due to the contact of the inner ring 15a on the outboard side is reduced, and the creep caused by the wear is suppressed. The For this reason, the wear of the inner ring contact surface 40 due to creep → axial force reduction, further creep generation → shaft wear → cracking from edge-shaped wear ends → durability degradation is suppressed.

  12 to 14 each show another embodiment of the present invention. Also in each of these embodiments, non-standard in a range from at least the vicinity of the inner ring contact surface 40 on the outer peripheral surface of the shaft portion 14a in the hub 14 to the shaft portion 14a including the corner R portion 42 with the inner ring contact surface 40. By providing the portion 30 of the structure, the strength and fatigue strength can be improved and the life can be extended by refining the structure and increasing the hardness. Further, by increasing the hardness of the inner ring contact surface 40, wear due to creep is reduced, and an increase in creep and a decrease in durability of the shaft portion 14a due to this are suppressed. In each of these embodiments, the matters other than those specifically described are the same as those in the eighth embodiment described with reference to FIGS. 10 and 11.

  The wheel bearing device of FIG. 12 is for the driven wheel of the wheel bearing device according to the eighth embodiment shown in FIGS. 10 and 11, and the shaft portion 14a of the hub 14 is the same as in the example of FIG. The central through hole 21 is not provided.

  The wheel bearing device of FIG. 13 is of an angular ball bearing type for driving wheel support, and the outer ring 2 does not have the vehicle body mounting flange 12 in the example of FIG. It is a cylindrical surface. The inner rings 15a and 15b are provided for each row, but the inner ring 15b on the inboard side is larger in thickness and axial dimension than the inner ring 15a on the outboard side. The inner rings 15a and 15b may be the same size in both rows.

The wheel bearing device of FIG. 14 is of the angular ball bearing type for supporting the drive wheels, like the wheel bearing device of FIG. 13, but the inner rings 15a and 15b in both rows are of the same size. Yes. In this example, the caulking portion 14b of the example of FIG. 13 is not provided in the hub 14, and the inner rings 15a and 15b are fixed in the axial direction by a constant velocity joint (not shown) coupled to the hub 14.
Although the wheel bearing device in FIGS. 13 and 14 is for driving wheel support, it may be a wheel bearing device for driven wheel support.

It is sectional drawing of the wheel bearing apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing of the hub of the bearing apparatus for wheels. It is a figure showing the example which carries out laser hardening of the principal part of the hub. It is sectional drawing of the wheel bearing apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing of the wheel bearing apparatus which concerns on 3rd Embodiment of this invention. It is sectional drawing of the wheel bearing apparatus which concerns on 4th Embodiment of this invention. It is sectional drawing of the wheel bearing apparatus which concerns on 5th Embodiment of this invention. It is sectional drawing of the wheel bearing apparatus which concerns on 6th Embodiment of this invention. It is sectional drawing of the wheel bearing apparatus which concerns on 7th Embodiment of this invention. It is sectional drawing of the wheel bearing apparatus which concerns on 8th Embodiment of this invention. It is sectional drawing of the hub of the bearing apparatus for wheels. It is sectional drawing of the wheel bearing apparatus which concerns on 9th Embodiment of this invention. It is sectional drawing of the wheel bearing apparatus which concerns on 10th Embodiment of this invention. It is sectional drawing of the wheel bearing apparatus which concerns on 11th Embodiment of this invention.

Explanation of symbols

1 ... inner member 2 ... outer member (outer ring)
DESCRIPTION OF SYMBOLS 3 ... Rolling element 6-9 ... Track surface 14 ... Hub 14a ... Shaft part 14b ... Clamping part 15, 15a, 15b ... Inner ring 20 ... Pilot part 17 ... Wheel mounting flange 30 ... Non-standard structure part 40 ... Inner ring contact Contact surface 41 ... Seal contact surface BR1 ... Bearing

Claims (10)

An inner member and an outer member that are rotatable relative to each other via a double row of rolling elements, and the inner member is fitted or coupled to a hub having a wheel mounting flange and a shaft portion of the hub. In a wheel bearing device having a component having a raceway surface,
The base material portion of the hub is a standard structure obtained by hot forging of a steel material, and has a non-standard structure portion on the outer peripheral surface of the shaft portion, and the non-standard structure is obtained by laser quenching. Is a wheel bearing device.   2. The inner member according to claim 1, wherein the inner member has a raceway surface on the hub and the component fitted or coupled to the shaft portion of the hub, and the inner member is separated from the outer member. A seal to be sealed is attached to an end of the outer member on the outboard side and slidably contacts a seal contact surface which is an outer peripheral surface portion between the raceway surface of the hub and the wheel mounting flange, thereby forming the non-standard structure of the hub. A wheel bearing device, wherein the portion is a portion that becomes the seal contact surface. A bearing having rolling elements interposed between the inner ring and the outer ring in a double row, and a hub having a shaft portion for fitting the inner ring of the bearing to the outer periphery and a wheel mounting flange. In the wheel bearing device in which the end surface of the inner ring on the outboard side contacts the inner ring contact surface extending from the end on the wheel mounting flange side to the outer diameter side,
The base material portion of the hub is a standard structure obtained by hot forging of a steel material, and includes a corner R portion with an inner ring contact surface from at least the vicinity of the inner ring contact surface on the outer peripheral surface of the shaft portion. A wheel bearing device having a non-standard structure portion in a range extending over a shaft portion, wherein the non-standard structure is a structure obtained by laser quenching.   The wheel bearing device according to claim 3, wherein the portion of the non-standard structure is provided up to a portion where the inner ring on the inboard side on the outer peripheral surface of the shaft portion is fitted.   5. The shaft according to claim 4, wherein the inner ring is fixed to the hub in the axial direction by pressing the end surface of the inner ring by a crimping portion obtained by crimping the inboard side end of the shaft portion of the hub to the outer diameter side. Wheel bearing device in which the outer peripheral surface near the inboard side end of the part has the same standard structure as the base material.   In any one of Claims 1 thru | or 5, the non-standard structure | tissue which is a structure | tissue obtained by laser hardening is a fine ferrite pearlite structure | tissue, an upper bainite structure | tissue, a lower bainite structure | tissue, and a tempered martensite structure | tissue. A wheel bearing device which is any one or at least a mixed structure of two or more of these structures.   The wheel bearing device according to any one of claims 1 to 6, wherein the hardness of the non-standard structure portion is 20 HRC or more and 40 HRC or less, and the hardness of the standard structure of the base material portion is 13 HRC or more and 25 HRC or less.   The wheel bearing device according to any one of claims 1 to 6, wherein the hardness of the non-standard structure portion is 40 HRC or more and the hardness of the standard structure of the base material portion is 13 HRC or more and 25 HRC or less.   The wheel bearing device according to any one of claims 1 to 8, wherein the non-standard structure, which is a structure obtained by laser quenching, is a structure obtained by quenching using YAG laser light.   The wheel bearing device according to any one of claims 1 to 8, wherein the non-standard structure, which is a structure obtained by laser quenching, is a structure obtained by quenching using a semiconductor laser beam.

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