JP2010089669A - Wheel bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing device which improves strength and fatigue strength of a screw hole for mounting to a wheel and a vehicle body, has superior durability against high stress repeatedly generated during turning of the vehicle, endures larger load, can reduce wear of an internal thread in the screw hole, can suppress axial force reduction/looseness of a bolt, and can suppress lowered productivity caused by the increase in steps. <P>SOLUTION: A hub 14 having a wheel mounting flange 17 equipped with a wheel mounting hole 18 is a hot-forged steel material. An inner surface of the wheel mounting hole 18 of the hub 14 is a non-standard structure portion 30, and the non-standard structure is a structure 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 some wheel bearing devices, a screw hole, which is a tap hole, is provided in a wheel mounting flange of a hub, and a wheel or a brake component is attached by a wheel bolt that is screwed into the screw hole. Further, there is a type in which a vehicle body mounting hole provided in a vehicle body mounting flange of an outer ring is a screw hole and is attached to a knuckle or the like of a suspension device of a vehicle body with a bolt screwed into the screw hole.
In such a wheel mounting flange or vehicle body mounting flange with a screw hole, the female screw must withstand repeated fatigue during turning of the vehicle and withstand heavy loads such as curb side impacts. .

  Therefore, an attempt was made to strengthen the screw holes of the wheel mounting flange and the vehicle body mounting flange. Conventionally, although it is not a countermeasure against hardening of a screw hole, in order to increase the fatigue strength of the component parts of the wheel bearing device, a method of improving the hardness by forging the entire part after forging has been proposed (for example, Patent Document 1). . In addition, a method for performing high-frequency heat treatment (for example, Patent Document 2) and a method for performing shot peening have been proposed (for example, Patent Document 3).

  However, in the case of increasing the hardness by refining the entire wheel mounting flange or vehicle body mounting flange, the number of processes is increased and the overall workability, for example, machinability and caulking, is increased by increasing the hardness. Cold workability such as machining may be reduced, and slip torque may be reduced due to a decrease in biting property of the hub bolt. In shot peening, the inner diameter portion of the screw hole is narrow, so that the work is limited. In the high frequency heat treatment, there are cases where it cannot be adopted depending on the part shape of the part to be treated. When high-frequency heat treatment is performed, problems such as partial melting of parts due to excessively high temperature and melting occur, and therefore high-frequency heat treatment cannot be performed.

In view of this, the present inventors cooled the wheel mounting flange or a part of the vehicle mounting flange (screw hole) that is red hot with a refrigerant during the hot forging process of the hub or at the end of the process. A method has been proposed in which a non-standard structure with increased hardness is obtained at that portion by recuperation or recuperation holding and tempering (for example, Patent Document 4).
JP-A-2005-003061 JP 2004-182127 A JP 2005-145313 A JP 2007-50857 A

  However, in the case of the technique disclosed in Patent Document 4 that uses forging heat, the undesired portion is cured by the scattered refrigerant reaching the portion other than the portion that is desired to be a non-standard structure, and shaved by subsequent turning. Problems such as difficulty.

  The object of the present invention is to improve the strength and fatigue strength of the screw holes for mounting the wheel and the vehicle body, and is excellent in durability against high stress repeatedly generated during turning of the automobile, withstanding a larger load, It is an object of the present invention to provide a wheel bearing device that can reduce wear of a female screw in a screw hole, suppress a decrease in bolt axial force and loosening, and suppress a decrease in productivity due to an increase in processes.

The wheel bearing device of the present invention has an inner member and an outer member that are rotatable with respect to each other via a double row of rolling elements, and is a component that constitutes all or part of the inner member or the outer member. In a wheel bearing device having a flange for mounting a wheel or a vehicle body, and having a screw hole in any of the flanges,
The part having the flange provided with the screw hole is a hot forged product of steel material, and this part has a base material portion having a standard structure, and an inner surface of the screw hole of the part is a non-standard structure portion. The non-standard structure is a structure obtained by laser quenching.
In addition, the standard structure is the structure obtained by cooling after heating to an austenite structure in order to homogenize the structure when it is cooled from the normalizing temperature, that is, the steel structure. Say.

According to the wheel bearing device having this configuration, the following effects can be obtained. Since the inner surface of the screw hole of the part is the part of the non-standard structure, the part of the non-standard structure is finer than the base material part made of the standard structure and has a hardness equal to or higher than that. Become. Such refinement of the structure and increased hardness improve the strength and fatigue strength of the screw hole, and when high stress is repeatedly generated during turning of the automobile, the screw hole of the wheel mounting flange or the vehicle body mounting flange It is possible to prevent cracks from occurring. In other words, the effect of crack generation → increase in the displacement of the stress generation site → increase in vehicle vibration → reduced durability of the components of the wheel bearing device provided with the screw hole is suppressed, thereby extending the life. Moreover, the bolt can be prevented from coming off. Further, due to the increase in hardness due to the non-standard structure, damage to the screw hole at the time of a heavy load is suppressed, and a higher load can be withstood. Furthermore, the wear of the female screw in the screw hole can be reduced, and the reduction and loosening of the axial force of the bolt can be suppressed.
Thus, the strength is increased and the life can be extended. 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.

  The part of the non-standard structure is obtained by laser quenching in particular, so that it is possible to prevent a part of the part having a flange provided with a screw hole from becoming too hot locally and not to melt down. . Further, when the non-standard structure portion is limited to the inner surface of the screw hole only, unlike the case where the entire part is made of a non-standard structure, workability such as machinability and caulking properties is reduced. Is minimized.

  Therefore, most of the entire part other than the inner surface of the screw hole is not hardened, 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. Unlike shot peening, an optical fiber cable or the like can be easily passed through a screw hole even if the inner diameter of the screw hole is narrow. Therefore, it is possible to irradiate the laser beam to a predetermined portion of the inner diameter surface of the screw hole.

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. Such refinement and increased hardness improve the fatigue strength of the non-standard structure part, and can withstand higher stress amplitude, that is, higher strength and longer life compared to parts consisting of only 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.

The inner member includes a hub having a wheel mounting flange and at least one inner ring fitted to the outer periphery of the hub, the screw hole being provided in the wheel mounting flange, and the screw hole of the hub. The inner surface may be a non-standard tissue part.
The inner member includes a hub having a wheel mounting flange and at least one inner ring fitted to the outer periphery of the hub, and the screw hole is provided in the wheel mounting flange. The inner surface of the screw hole of the hub may be a non-standard tissue part.
The inward member includes a hub having a wheel mounting flange and at least one inner ring fitted to the outer periphery of the hub. The screw hole is provided in the wheel mounting flange, and the screw hole is a brake rotor. The inner surface of the screw hole of the hub may be a non-standard tissue part.

The outer member has a vehicle body mounting flange, the screw mounting hole is provided in the vehicle body mounting flange of the outer member, and the inner surface of the screw hole of the outer member is a non-standard tissue part. Also good.
The inner member may be a hub and one inner ring fitted to the outer periphery of the inboard side end of the hub, and the hub and the inner ring may be formed with raceways in each row.
The inner member may have a plurality of inner rings fitted on the outer periphery of the hub, the hub may not have a raceway surface, and each inner ring may have a raceway surface.

The hardness of the non-standard structure portion may be 20 HRC or more and 40 HRC or less, and the hardness of the standard structure of the base material portion 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 portion 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 may be 40 HRC or more, and the hardness of the standard structure 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 of the base material hardness, in order to improve fatigue strength by increasing hardness. The material used for the hub is carbon steel (C content 0.4 to 0.8%) or the like, 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 taking into account the portion into which the hub bolt is press-fitted, it is preferable that the maximum is 25 HRC.
The hardness of the non-standard structure portion may be 40 HRC or more, and the hardness of the standard structure 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.

  The depth of the non-standard tissue is preferably 0.1 mm or more and 1.5 mm or less. In the case of 0.1 mm or less, the non-standard structure is too thin and the effect cannot be expected. Further, if the thickness is 1.5 mm or more, the laser irradiation time is long to obtain a deep non-standard structure. Therefore, the part other than the irradiation range is heated, and the irradiation range is less likely to be rapidly cooled after the irradiation. Problems such as deterioration in accuracy such as runout 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, said YAG
The time required for laser quenching per workpiece can be further shortened compared to those using laser light or infrared laser light, and the number of man-hours can be reduced. 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.

The wheel bearing device of the present invention has an inner member and an outer member that are rotatable with respect to each other via a double row of rolling elements, and is a component that constitutes all or part of the inner member or the outer member. In a wheel bearing device having a flange for mounting a wheel or a vehicle body, and having a screw hole in any of the flanges,
The part having the flange provided with the screw hole is a hot forged product of steel material, and this part has a base material portion having a standard structure, and an inner surface of the screw hole of the part is a non-standard structure portion. In addition, since the non-standard structure is a structure obtained by laser quenching, the strength and fatigue strength of the screw holes for mounting the wheel and the vehicle body are improved, and the high stress repeatedly generated during turning of the automobile is increased. On the other hand, it has excellent durability, can withstand a larger load, can reduce the wear of the internal thread of the screw hole, can suppress the decrease in bolt axial force and loosening, and can suppress the decrease in productivity due to an increase in the number of processes.

  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 a third generation type driving wheel support. 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 formed 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 a bearing outer ring, and 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 outer side in the vehicle width direction when attached to the vehicle body is referred to as the outboard side, and the side closer to the center in the vehicle width direction is referred to as the inboard side. At a plurality of locations in the circumferential direction of the vehicle body mounting flange 12, vehicle body mounting holes 13 each having a screw hole whose inner surface is a female screw are provided.

  As shown in FIGS. 1 and 2, 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 14 a 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. An inner ring fitting surface 16 having a step and a small diameter is provided at the inboard side end on the outer periphery of the shaft portion 14 a of the hub 14, and the inner ring 15 is fitted to the inner ring fitting surface 16. 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 hub 14 has a wheel mounting flange 17 on the outer periphery of the end on the outboard side of the shaft portion 14a, and a wheel formed of screw holes whose inner surfaces are female threads at a plurality of locations in the circumferential direction of the wheel mounting flange 17. A mounting hole 18 is provided. A wheel bolt (not shown) is screwed into each wheel mounting hole 18, and the wheel HL superimposed on the side surface on the outboard side of the wheel mounting flange 17 is fixed by the wheel bolt.

  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 that serves as a portion for guiding the brake rotor BR 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. It 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.

  In the wheel bearing device for the driven wheel, as shown in FIG. 4, the hub 14 does not have the through hole 21 in the example of FIG. Further, in the wheel bearing device for the driven wheel in the example of FIG. 4, the inner ring 15 is connected to the hub 14 by a crimping portion 14 b in which the inboard side end of the shaft portion 14 a of the hub 14 is crimped to the outer diameter side. Are fixed in the axial direction.

  1, 2, and 4, the hub 14, the inner ring 15, and the outer member 2 that are parts constituting the inner member 1 are all hot forged products of steel. Among these, the inner surface of the wheel mounting hole 18 formed of the screw hole of the wheel mounting flange 17 of the hub 14 is a non-standard tissue portion 30. Further, the inner surface of the vehicle body mounting hole 13 formed of a screw hole in the vehicle body mounting flange 12 of the outer member 2 is a non-standard tissue portion 30. The base material portion of the hub 14 has a standard structure. These non-standard tissue portions 30 are locally provided on the hub 14 or the outer member 2.

As shown in FIG. 2A, the inner surface 18 a of the wheel mounting hole 18 in the wheel mounting flange 17 is a non-standard tissue portion 30. This non-standard tissue portion 30 is locally provided on the hub 14, and is a predetermined small distance La (La is a distance from the inner surface 18a of the wheel mounting hole 18 in the wheel mounting flange 17 to the radially outer side. For example, a range extending about half of the thickness of the wheel mounting flange 17 is a non-standard tissue portion 30. However, the non-standard tissue portion 30 is not limited to the above range. For example, the non-standard tissue portion 30 may be in a range extending from the inner surface 18a of the wheel mounting hole 18 to several tens of μm radially outward.
Further, as shown in FIG. 2B, a predetermined small distance Lb (Lb is, for example, 1 of the thickness of the vehicle body mounting flange 12 from the inner surface 13a of the vehicle body mounting hole 13 in the vehicle body mounting flange 12 to the radially outward side. The extending range is the non-standard tissue portion 30. However, the non-standard tissue portion 30 is not limited to the above range. For example, the non-standard tissue portion 30 may be in a range from the inner surface 13a of the vehicle body mounting hole 13 to several tens of μm radially outward.

  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, for example, carbon steel having a C content of 0.4% or more and 0.8% or less, such as S53C. However, the steel material used as a raw material is not limited to S53C. The inner surface 18a of the wheel mounting hole 18 of the hub 14 subjected to the turning process and the inner surface 13a of the vehicle body mounting hole 13 are 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, when the strength and fatigue strength of the inner surface 18a of the wheel mounting hole 18 of the hub 14 and the inner surface 13a of the vehicle body mounting hole 13 of the outer member 2 are improved, the hardening range (non-standard tissue portion 30). The surface hardness is set to 40 HRC or more. When toughness is required, it is desirable that the surface hardness of the cured range be 20 HRC or more and 40 HRC or less by high temperature tempering. The base material portion of the hub 14 and the outer member 2 is a standard structure portion, 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.
Thereafter, induction hardening of the raceway surface 6 and the like and the inner ring fitting surface 16 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 and the outer member 2, the order of laser hardening and induction hardening may be reversed. Tempering is performed by putting the hub 14 and the outer member 2 in a heating furnace to heat the whole or by high-frequency heating, and the laser beam whose output, defocus amount, and feed rate are adjusted. It may be one that is partially tempered by heating.

  According to the wheel bearing device of this configuration, the following effects can be obtained. Since the inner surface 18a of the wheel mounting hole 18 of the hub 14 and the inner surface 13a of the vehicle body mounting hole 13 are portions 30 of the non-standard structure, the structures of the inner surfaces 18a and 13a are refined and the hardness is equal to or higher than that. Become. Such refinement of the structure and increase in hardness improve the strength and fatigue strength in the screw holes, and when high stress is repeatedly generated during turning of the automobile, the wheel mounting flange 17 and the vehicle body mounting flange 12 The occurrence of cracks in each screw hole is suppressed. In other words, the effect of crack generation → increase in the displacement of the stress generation site → increase in vehicle vibration → reduced durability of the components of the wheel bearing device provided with the screw hole is suppressed, thereby extending the life. Moreover, the bolt can be prevented from coming off.

Further, due to the increase in hardness due to the non-standard structure, damage to the screw hole at the time of a heavy load is suppressed, and a higher load can be withstood. Furthermore, the wear of the female screw in the screw hole can be reduced, and the reduction and loosening of the axial force of the bolt can be suppressed. Further, a desired tightening torque can be obtained.
Thus, the strength is increased and the life can be extended. 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.

  Since the non-standard tissue portion 30 is obtained by laser quenching in particular, a part of the hub 14 having the wheel mounting flange 17 provided with the wheel mounting hole 18 and a part of the outer member 2 are locally provided. It prevents the temperature from becoming too high and does not melt away. In addition, it is possible to maintain the deflection accuracy of the wheel mounting flange 17 with high accuracy. When the portion 30 to be the non-standard structure is limited to only the inner surface 18a of the wheel mounting hole 18 and the inner surface 13a of the vehicle body mounting hole 13, the entire hub 14 and the entire outer member 2 are set to the non-standard structure. Unlike the case, deterioration of workability such as machinability and caulking property can be minimized.

  Therefore, most of the hub 14 other than the inner surface 18a of the wheel mounting hole 18 is not cured, and grinding processing after tempering can be performed easily and quickly. Further, most of the outer member 2 other than the inner surface 13a of the vehicle body mounting hole 13 is not hardened, and grinding processing after tempering can be performed easily and quickly. 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. Further, unlike shot peening, even if the inner diameter of the wheel mounting hole 18 or the vehicle body mounting hole 13 is narrow, an optical fiber cable or the like can be easily passed through these mounting holes 18 and 13. Therefore, it is possible to irradiate laser light to predetermined locations on the inner diameter surfaces of the mounting holes 18 and 13.

Any one of the fine ferrite / pearlite structure, the upper bainite structure, the lower bainite structure, and the tempered martensite structure, or at least the mixed structure of two or more of these structures, the portion 30 of the non-standard structure is a 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. By such structure refinement and hardness increase, the strength and fatigue strength of the non-standard structure part are improved, and it withstands high stress amplitude, that is, increased in strength, compared to a hub consisting only of a normal standard structure, Long life can be achieved. 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.
In the first embodiment shown in FIG. 1, the vehicle body attachment hole 13 is a bolt insertion hole without a female screw, the inner surface of this bolt insertion hole is a non-standard tissue portion 30, and the wheel attachment hole 18 is a screw hole. The inner surface 18a may be a non-standard tissue portion 30. In the first embodiment shown in FIG. 1, a hub bolt having serrations may be press-fitted with at least one or both of the wheel mounting hole 18 and the vehicle body mounting hole 13 as a bolt press-fitting hole.

Another embodiment of the present invention will be described with reference to FIGS.
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.

  In each of the embodiments shown in FIGS. 4 to 11, the inner surface of the wheel mounting hole 18 or the vehicle body mounting hole 13 formed of each screw hole is used as a non-standard tissue portion 30, and the non-standard tissue portion 30 is obtained by laser hardening. It is what was done. Strengthening and fatigue strength are improved by extending the structure of the non-standard structure portion 30 and increasing the hardness, thereby extending the life. By increasing the hardness, the wear of the female screw of the wheel mounting hole 18 or the vehicle body mounting hole 13 is reduced, and the reduction or loosening of the axial force of the wheel bolt or the vehicle body mounting bolt can be suppressed. Also in each of these embodiments, in the case having both the wheel mounting flange 17 and the vehicle body mounting flange 12 (each embodiment of FIGS. 4, 5, 6, and 10), one of the holes is provided. That is, only one of the wheel mounting hole 18 and the vehicle body mounting hole 13 may be a screw hole, and the inner surface of the screw hole may be a non-standard tissue portion 30. Moreover, it is good also as what press-fits the hub bolt which has a serration as at least any one or both of the wheel attachment hole 18 and the vehicle body attachment hole 13 as a bolt press-fit hole.

FIG. 4 shows the wheel bearing device in the embodiment of FIG. 1 for supporting a driven wheel. In this embodiment, the hub 14 does not have the through hole 21 at the center. Other configurations are the same as those in the example of FIG. 1, and the same operational effects as in FIG.
The wheel bearing device of FIG. 5 is of a tapered roller bearing type for driving wheel support, and the inner member 1 is a double row in which the hub 14 and the outer periphery of the shaft portion 14a of the hub 14 are fitted. It consists of an inner ring 15. The hub 14 has a wheel mounting flange 17. The inner ring 15 is provided for each row. The outer member 2 is made up of a single component and has a vehicle body mounting flange 12. In this wheel bearing device, a hub 14 is provided as a separate part from a finished product bearing composed of a double row bearing composed of an inner ring 15, an outer member 2, a rolling element 3, and the like.

FIG. 6 shows the wheel bearing device of the example of FIG. 5 for supporting the driven wheel, and the hub 14 does not have the central through-hole 21. Further, the inner ring 15 is fixed to the hub 14 by a caulking portion 14 b of the hub 14. Other configurations are the same as the example of FIG.
The wheel bearing device of FIG. 7 is of an angular ball bearing type for driving wheel support, 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 an inner ring 15. The inner ring 15 is provided for each row, and the inner ring 15 on the inboard side is larger in thickness and axial dimension than the inner ring 15 on the outboard side. The inner ring 15 is fixed to the hub 14 in the axial direction by a caulking portion 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.

FIG. 8 shows the wheel bearing device of the example of FIG. 7 for supporting the driven wheel, and the hub 14 does not have the central through-hole 21. Other configurations are the same as the example of FIG.
The wheel bearing device of FIG. 9 includes the hub 14 and a double row of inner rings 15 fitted on the outer periphery of the shaft portion 14a of the hub 14 as in the wheel bearing device of FIG. . The outer member 2 is composed of one integral part and does not have the vehicle body mounting flange 12. In this example, the two inner rings 15 are the same size, and the inner ring 15 is fixed in the axial direction to the hub 14 by a constant velocity joint (not shown) coupled to the hub 14 without caulking. Is called.

The wheel bearing device of FIG. 10 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 joint outer ring 32 is formed with raceway surfaces 6 and 7 in each row. The outer member 2 is made of one component and has a vehicle body mounting flange 12.
The wheel bearing device of FIG. 11 is of the second generation type outer ring rotating type, the outer member 2 has a wheel mounting flange 17, and the inner member 1 extends from the double row inner ring 15. Become.

It is sectional drawing of the wheel bearing apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing of the components of the wheel bearing apparatus, FIG. 2 (A) is sectional drawing of a hub, FIG.2 (B) is sectional drawing of an outward member. 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 wheel bearing apparatus which concerns on 9th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inner member 2 ... Outer member 3 ... Rolling body 6-9 ... Track surface 12 ... Body mounting flange 13 ... Body mounting hole 14 ... Hub 15 ... Inner ring 17 ... Wheel mounting flange 18 ... Wheel mounting hole 30 ... Non-standard organization

Claims (12)

An inner member and an outer member that are rotatable with respect to each other via a double row of rolling elements, and parts for constituting all or part of the inner member or the outer member are attached to a wheel or a vehicle body. In a wheel bearing device having a flange and provided with a screw hole in any of the flanges,
The part having the flange provided with the screw hole is a hot forged product of steel material, and this part has a base material portion having a standard structure, and an inner surface of the screw hole of the part is a non-standard structure portion. A wheel bearing device, wherein the non-standard structure is a structure obtained by laser hardening.   The non-standard structure which is a structure obtained by laser quenching according to claim 1 is any one of a fine ferrite / pearlite structure, an upper bainite structure, a lower bainite structure, a tempered martensite structure, or at least of these structures. A wheel bearing device which is a mixed structure of two or more of them.   3. The wheel mounting flange according to claim 1, wherein the inner member includes a hub having a wheel mounting flange and at least one inner ring fitted to an outer periphery of the hub, and the screw hole is formed in the wheel mounting flange. A wheel bearing device provided, wherein an inner surface of the screw hole of the hub is a non-standard tissue part.   4. The wheel mounting flange according to claim 1, wherein the inner member includes a hub having a wheel mounting flange and at least one inner ring fitted to an outer periphery of the hub. A wheel bearing device in which the screw hole is provided in the screw hole, and the screw hole can be attached to a wheel, and the inner surface of the screw hole of the hub is a non-standard tissue part.   5. The wheel mounting flange according to claim 1, wherein the inner member includes a hub having a wheel mounting flange and at least one inner ring fitted to an outer periphery of the hub. A wheel bearing device in which the screw hole is provided in the screw hole, the screw hole can be attached to a brake rotor, and the inner surface of the screw hole of the hub is a non-standard tissue part.   6. The outer member according to claim 1, wherein the outer member has a vehicle body mounting flange, and the screw press-fitting hole is provided in the vehicle body mounting flange of the outer member. A wheel bearing device in which an inner surface of the screw hole is a non-standard tissue part.   7. The inner member according to claim 1, wherein the inner member includes a hub and one inner ring fitted to an outer periphery of an inboard side end of the hub, and each row is arranged in the hub and the inner ring. A wheel bearing device in which a raceway surface is formed.   The inner member according to any one of claims 3 to 5, wherein the inner member has a plurality of inner rings fitted to an outer periphery of the hub, the hub does not have a raceway surface, and the inner rings have a raceway surface. Wheel bearing device having.   The wheel bearing according to any one of claims 1 to 8, 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. apparatus.   9. The wheel bearing device according to claim 1, wherein the hardness of the portion of the non-standard structure 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 10, 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 10, wherein the non-standard structure, which is a structure obtained by laser quenching, is a structure obtained by quenching using a semiconductor laser beam.

Images