JP5641705B2 - Wheel bearing device - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel bearing device that rotatably supports a drive wheel of a vehicle such as an automobile, and more particularly to a wheel bearing device that is light and compact and improves the strength and durability of a bearing. .

  2. Description of the Related Art Conventionally, a wheel bearing device for supporting a wheel of an automobile or the like supports a hub wheel for mounting a wheel rotatably via a double row rolling bearing, and includes a drive wheel and a driven wheel. For structural reasons, an inner ring rotation method is generally used for driving wheels, and an inner ring rotation method and an outer ring rotation method are generally used for driven wheels. This wheel bearing device has a structure called a first generation in which a wheel bearing composed of a double-row angular ball bearing or the like is fitted between a knuckle and a hub wheel constituting a suspension device, and is an outer member. 2nd generation structure with body mounting flange or wheel mounting flange formed directly on the outer periphery of the wheel, 3rd generation structure with one inner rolling surface formed directly on the outer periphery of the hub wheel, or constant speed with the hub wheel It is roughly classified into a fourth generation structure in which the inner rolling surface is directly formed on the outer periphery of the outer joint member of the universal joint.

  Conventionally, for the purpose of reducing manufacturing costs, it has been considered to manufacture a hub ring and a double row angular ball bearing by deep drawing using a plate material. In this way, when manufacturing hub rings and double row angular contact ball bearings by deep drawing, if a thick plate is used to ensure sufficient strength as the base material, processing is difficult and the shape of the bent part・ Since the accuracy tends to decrease, a precision technique for improving the accuracy is required, and the production efficiency deteriorates despite the press working.

  As a solution to these problems, a wheel bearing device as shown in FIG. 9 is known. This wheel bearing device 50 is referred to as a third generation structure, and includes a hub ring 51 and a double-row angular ball bearing 52. The hub ring 51 is disposed radially outward on one shaft end side of the hollow shaft portion 53. A plurality of cut and raised pieces 54 extending in the direction and a plurality of tongue pieces 55 extending along the axial direction are provided alternately in the circumferential direction. The double-row angular ball bearing 52 is mounted on the shaft 53 and mounted with a wheel or brake rotor (not shown) positioned axially on one side of the cut-and-raised piece 54. It is fixed by a hub bolt 56 that is fixed through. Further, each tongue piece 55 is provided with a radially outwardly bulging portion 55a on the root side to form a pilot portion.

  The double row angular contact ball bearing 52 includes an outer member 57 in which double row outer rolling surfaces 57a and 57a are formed on the inner periphery, a hub wheel 51 in which one inner rolling surface 51a is formed on the outer periphery, An inner ring 58 that is externally fitted to the small-diameter stepped portion 53a of the shaft portion 53 of the hub wheel 51 and has an inner rolling surface 58a formed on the outer periphery, and double rows of balls 60 and 60 arranged via a cage 59 are provided. I have.

  A plurality of cut-and-raised pieces 61 extending radially outward and a plurality of tongue pieces 62 extending along the axial direction are provided alternately on one axial end side of the outer member 57 in the circumferential direction. It has been. A knuckle (not shown) is attached to one side of the cut and raised piece 61 in a state of being positioned in the axial direction and is fixed by a fixing bolt (not shown). In addition, the double row angular ball bearings 52 are centered with respect to the knuckle by defining the dimensional relationship so that each tongue piece 55 and the inner peripheral surface of the through hole of the knuckle are in close contact with each other. The end portion of the small diameter step portion 53a of the shaft portion 53 of the hub wheel 51 is bent radially outward by rolling caulking, and the inner ring 58 is fixed in the axial direction.

  The outer member 57 of the hub wheel 51 and the double-row angular ball bearing 52 is manufactured through a cold forging process, a cutting process, and a bending process using a cylindrical tube as a base material, so that it does not require a precision technique. At the same time, it is not necessary to retrofit parts for centering, so that the manufacturing cost can be reduced.

JP 2003-25803 A

  However, in this conventional wheel bearing device 50, when a large moment load is applied to the cut and raised pieces 54 and 61 of the hub wheel 51 and the outer member 57, the cut and raised pieces 54 and 61 are a single plate. However, there is a problem that strength and rigidity are insufficient and desired durability cannot be obtained. Further, the hub bolt 56 is fixed to the cut-and-raised piece 54 of the hub wheel 51, but the fixing force is insufficient because the press-fitted width of the hub bolt 56 is equal to the plate thickness, and the hub bolt 56 may be loosened.

  Here, if a thick plate material is used to ensure sufficient strength as the base material, it is difficult to process and the shape and accuracy of the bent part are likely to deteriorate, so precision technology to improve accuracy is required. Is done. In this case, in spite of the press working, not only the production efficiency is deteriorated and the manufacturing cost is increased, but also it is difficult to achieve the weight reduction.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wheel bearing device in which the strength and durability of the bearing are improved together with reduction in weight and size.

In order to achieve such an object, the invention described in claim 1 of the present invention includes an outer member in which a double-row arc-shaped outer rolling surface is integrally formed on the inner periphery, and an outer end portion. A wheel mounting flange for mounting a wheel is integrally formed, and an arcuate inner rolling surface facing one of the double-row rolling surfaces on the outer periphery, and a cylindrical shape extending in the axial direction from the inner rolling surface A hub ring formed with a small-diameter step portion, and an arc-shaped inner rolling surface that is press-fitted into the small-diameter step portion of the hub ring via a predetermined shimiro and faces the other of the outer rolling surfaces of the double row on the outer periphery. An inner member formed of an inner ring formed with an inner ring, a double row of balls accommodated between the rolling surfaces of the inner member and the outer member via a cage, and the outer member. And a seal attached to the opening of the annular space formed between the inner member and the inner member, and the end of the small-diameter stepped portion In a self-retained wheel bearing device in which the inner ring is fixed in the axial direction with respect to the hub ring by a caulking portion formed by plastic deformation outward in the direction, the hub ring, the inner ring, and the outer member are It is formed by cold plastic working from a plate material or a pipe material, and the outer diameter of the outer member is recessed between the annular recess and the inner periphery of the outer circumferential surface of the double row. An annular convex portion projecting inward in the direction is formed in a flat shape, and a connecting portion between the outer diameter and the annular concave portion is formed in an arc shape having a predetermined radius of curvature, and this portion is set to a substantially uniform thickness. The radius of curvature R of the connecting portion is set to be in the range of R = 1.5 to 2.5 Rw, where Rw is the radius of the ball.

As described above, the self-retaining structure wheel bearing in which the inner ring is axially fixed to the hub ring by the caulking portion formed by plastically deforming the end of the small-diameter stepped portion of the hub ring radially outward. In the device, the hub ring, the inner ring, and the outer member are formed from a plate material or pipe material by cold plastic working, and the axially central portion of the outer diameter of the outer member is recessed to form an annular recess and an inner periphery . An annular convex portion projecting radially inward between the outer rolling surfaces of the row is formed in a flat shape, and a connecting portion between the outer diameter and the annular concave portion is formed in an arc shape having a predetermined radius of curvature. The parts are set to have a substantially uniform thickness, and the radius of curvature R of the joint is set to be in the range of R = 1.5 to 2.5 Rw when the radius of the ball is Rw.・ Along with compactness, it prevents cracks in the shoulder and Can contact ellipse of the ball at the moment the load is prevented from edge load is generated riding a shoulder, it is possible to provide a wheel bearing apparatus with improved strength and durability of the bearing. Further, the thickness is not reduced and the rigidity is not lowered, and the thickness is increased and the workability of the plastic working is not lowered.

  According to a second aspect of the present invention, hub bolt insertion holes are formed by punching in the circumferential direction of the wheel mounting flange, and the hub bolt insertion holes are formed by burring after punching of the hub bolt insertion holes. If the edge is formed so as to protrude, the press-fitting width of the hub bolt can be ensured, and the hub bolt can be prevented from loosening over a long period of time, thereby increasing the fixing force.

  According to a third aspect of the present invention, the fixing bolt insertion holes are formed in the circumferentially equidistant of the vehicle body mounting flange by punching, and the fixing bolts are fixed by burring after the fixing bolt insertion holes are punched. If the edge of the insertion hole protrudes, the press-fitting width of the fixing bolt can be ensured, and the fixing bolt can be prevented from loosening over a long period of time and the fixing force can be increased.

Further, as in the invention according to claim 4 , the wheel mounting flange is formed in a circular shape, and radially extends from an annular base portion on the inner side surface of the wheel mounting flange, and is set to be slightly thick. If the ribs are formed, the hub wheel can be reduced in weight and the strength and rigidity of the wheel mounting flange can be increased, and durability can be ensured even if a large moment load is applied to the wheel mounting flange. it can.

If the wheel mounting flange is divided into four to six extending radially from the annular base as in the invention described in claim 5 , the hub wheel can be reduced in weight and size. In addition, when fastening the outer member to the knuckle, the fixing bolt can be easily fastened with a tightening tool or the like without being disturbed by the wheel mounting flange, thereby simplifying the assembly work. Can do.

Further, as in the invention described in claim 6 , a cylindrical inner diameter portion of the brake rotor is externally fitted to an outer edge portion of the wheel mounting flange via a predetermined fitting clearance, and has a diameter with respect to the wheel mounting flange. If guided in the direction, a pilot portion as in the prior art becomes unnecessary, and the hub wheel can be reduced in weight.

Further, as in the invention according to claim 7 , if the inner edge of the brake rotor is formed to be bent toward the inner side, and the inner edge is in contact with the outer end of the wheel mounting flange, When a large moment load is applied to the wheel mounting flange, the brake rotor can suppress deformation and increase the rigidity of the wheel mounting flange.

Further, as in the invention described in claim 8 , the inner ring extends in the axial direction from the large diameter side of the inner rolling surface, and is a cylindrical shape that serves as a fitting portion or a sliding contact portion of the inner side seal. A shoulder, a large end formed by bending inward in the radial direction from the shoulder, and a cylindrical small end extending in the axial direction from the small diameter side of the inner rolling surface. Is pressed into the small-diameter step portion in a state of abutting against the shoulder portion of the hub wheel, and the inner ring is fixed in the axial direction with a predetermined bearing preload applied by the crimping portion. It can be formed with a uniform thickness and high accuracy, can increase strength and rigidity, and can easily apply a desired bearing preload.

Further, as in the invention described in claim 9 , the plate material or pipe material is heated at a temperature equal to or lower than the A1 transformation point before plastic working, and is divided into plate-like pearlite of the structure to be spheroidized annealing. In this case, the material is softened to facilitate plastic working and finish with high accuracy.

Further, as in the invention according to claim 10 , if the hub ring is heated or soaked to a predetermined temperature before heat treatment and then subjected to stress relief annealing for cooling at a predetermined speed, plastic working is performed. The internal stress generated by the above can be reduced, so that deformation due to heat treatment can be suppressed, and the allowance for subsequent grinding and the like can be reduced.

The wheel bearing device according to the present invention has an outer member in which a double-row arc-shaped outer rolling surface is integrally formed on the inner periphery, and a wheel mounting flange for mounting the wheel on the outer end. A hub wheel having an arcuate inner rolling surface facing one of the double-row rolling surfaces on the outer periphery, and a cylindrical small-diameter stepped portion extending in the axial direction from the inner rolling surface, And an inner member formed of an inner ring that is press-fitted into a small-diameter step portion of the hub wheel via a predetermined shimiro and has an arc-shaped inner rolling surface facing the other of the outer rolling surfaces of the double row on the outer periphery. And a double row of balls accommodated between the rolling surfaces of the inner member and the outer member via a cage, and the outer member and the inner member. And a seal attached to the opening of the annular space, and the end of the small diameter step is plastically deformed radially outward. In the self-retaining wheel bearing device in which the inner ring is fixed in the axial direction with respect to the hub ring by the crimped portion, the hub ring, the inner ring, and the outer member are cold plastic from a plate material or a pipe material. An annular convex portion formed by machining and having an axial central portion of the outer diameter of the outer member recessed, and an annular convex portion projecting radially inward between the outer rolling surfaces of the double row on the inner periphery Is formed in a flat shape, and the connecting portion between the outer diameter and the annular recess is formed in an arc shape having a predetermined radius of curvature, and this portion is set to a substantially uniform thickness, and the curvature radius R of the connecting portion is set. However, when the radius of the ball is Rw, it is set to be in the range of R = 1.5 to 2.5Rw, so it is possible to prevent the shoulder from cracking with light weight and compactness. And contact with the ball when turning moment is applied Circle can be prevented from edge load is generated riding a shoulder, it is possible to provide a wheel bearing apparatus with improved strength and durability of the bearing. Further, the thickness is not reduced and the rigidity is not lowered, and the thickness is increased and the workability of the plastic working is not lowered.

It is a longitudinal section showing a 1st embodiment of a bearing device for wheels concerning the present invention. It is a side view of FIG. It is the A section enlarged view of FIG. It is the B section enlarged view of FIG. It is a longitudinal cross-sectional view which shows the hub ring single-piece | unit of FIG. It is a longitudinal cross-sectional view which shows the outer member single-piece | unit of FIG. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the wheel bearing apparatus which concerns on this invention. FIG. 8 is a side view of FIG. 7. It is a longitudinal cross-sectional view which shows the conventional wheel bearing apparatus.

  The outer member integrally formed with the outer circumferential rolling surface of the double-row arc shape on the inner periphery and the wheel mounting flange for attaching the wheel to the end portion on the outer side are integrally formed, and the double-row on the outer periphery. A hub ring formed with an arcuate inner rolling surface facing one of the rolling surfaces, a cylindrical small-diameter step portion extending in the axial direction from the inner rolling surface, and a predetermined diameter on the small-diameter step portion of the hub ring. An inner member formed by an inner ring that is press-fitted through an outer periphery and has an arc-shaped inner rolling surface facing the other of the outer rolling surfaces of the double row on the outer periphery, and the inner member and the outer member. A double row of balls accommodated in a rollable manner via a cage between both rolling surfaces of the member and an opening of an annular space formed between the outer member and the inner member. The hub is formed by a crimped portion formed by plastically deforming an end portion of the small-diameter stepped portion radially outward. In the wheel bearing device in which the inner ring is fixed in the axial direction, the hub ring, the inner ring, and the outer member are formed of a plate material or a pipe material by plastic working, and the wheel mounting flange is equally spaced in the circumferential direction. The hub bolt insertion holes are formed by punching, and the edge of the hub bolt insertion hole protrudes by burring after the hub bolt insertion holes are punched.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 is a longitudinal sectional view showing a first embodiment of a wheel bearing device according to the present invention, FIG. 2 is a side view of FIG. 1, FIG. 3 is an enlarged view of part A of FIG. 1, and FIG. 1 is an enlarged view of a portion B in FIG. 1, FIG. 5 is a longitudinal sectional view showing a single hub wheel in FIG. 1, and FIG. 6 is a longitudinal sectional view showing a single outer member in FIG. In the following description, the side closer to the outer side of the vehicle when assembled to the vehicle is referred to as the outer side (left side in FIG. 1), and the side closer to the center is referred to as the inner side (right side in FIG. 1).

  This wheel bearing device is referred to as a third generation structure on the driven wheel side, and includes a plurality of balls 3, 3, which are accommodated so as to roll between the inner member 1 and the outer member 2, and both members 1, 2. And. The inner member 1 includes a hub ring 4 and an inner ring 5 press-fitted into the hub ring 4 through a predetermined shimiro.

  The hub wheel 4 integrally has a wheel mounting flange 6 for mounting a wheel (not shown) at an end portion on the outer side, and one (outer side) arcuate inner rolling surface 4a on the outer periphery. A cylindrical small diameter step portion 4c extending in the axial direction from the inner rolling surface 4a via the shoulder portion 4b is formed. Hub bolts 6a are implanted in the wheel mounting flange 6 in a circumferentially equal distribution, and circular holes 6b are formed between the hub bolts 6a. The circular hole 6b can not only contribute to weight reduction, but also a fastening jig such as a wrench can be inserted from the circular hole 6b in the assembly / disassembly process of the apparatus, and the work can be simplified.

  As shown in an enlarged view in FIG. 3, hub bolt insertion holes 7 are formed in the wheel mounting flange 6 at equal intervals in the circumferential direction by punching, and after the hub bolt insertion holes 7 are punched, the hub bolt insertion holes 7 are formed by burring. The edge part of is protruded and formed. Thereby, the press-fitting width of the hub bolt 6a can be ensured, and the hub bolt 6a can be prevented from loosening over a long period of time, thereby increasing the fixing force. Further, on the inner side surface of the wheel mounting flange 6, ribs 6 d that extend radially from the annular base portion 6 c and reach the edge of the hub bolt insertion hole 7 are formed with a slightly thicker wall ( (See FIG. 2). Accordingly, the strength and rigidity of the wheel mounting flange 6 can be increased while reducing the weight of the hub wheel 4, and durability can be ensured even when a large moment load is applied to the wheel mounting flange 6.

  Further, as shown in FIG. 3, a pilot member 8 for guiding the wheel and a brake rotor (not shown) is integrally joined to the outer side surface of the wheel mounting flange 6 by welding. The pilot member 8 has an inrow portion 9 formed at an end thereof, and is fitted into the step portion of the wheel mounting flange 6 via a predetermined fitting clearance. The centering accuracy between the pilot member 8 and the hub wheel 4 can be increased by the inrow portion 9.

  As shown in FIG. 1, the inner ring 5 is formed with the other (inner side) arcuate inner rolling surface 5a on the outer periphery, and extends in the axial direction from the large diameter side of the inner rolling surface 5a. A cylindrical shoulder portion 10 serving as a fitting portion of the seal 22 to be engaged, a large end portion 11 formed by bending radially inward from the shoulder portion 10, and an axial direction from the small diameter side of the inner rolling surface 5a A cylindrical small end portion 12 is provided. The small end portion 12 is pressed into the small diameter step portion 4c in a state of abutting against the shoulder portion 4b of the hub wheel 4 to constitute a back-to-back type double row angular ball bearing, and the end portion of the small diameter step portion 4c is made plastic. It is fixed in the axial direction in a state where a predetermined bearing preload is applied by a deformed caulking portion 4d, thereby forming a so-called self-retaining structure. By adopting such a configuration, it is possible to form with a uniform thickness and high accuracy, to increase strength and rigidity, and to easily apply a desired bearing preload.

  The outer member 2 integrally has a vehicle body mounting flange 13 to be attached to a knuckle (not shown) at an end on the inner side, an annular convex portion 14 projecting radially inward on the inner periphery, Double-row arc-shaped outer rolling surfaces 2 a and 2 a are integrally formed on both sides of the annular convex portion 14. Further, fitting portions 15 and 16 of seals 21 and 22 to be described later are formed at both ends of the double row outer rolling surfaces 2a and 2a.

  Fixing bolt insertion holes 17 are formed in the vehicle body mounting flange 13 at equal intervals in the circumferential direction by punching, and the edge of the fixing bolt insertion hole 17 protrudes by burring after the fixing bolt insertion holes 17 are punched. Has been. Thereby, the press-fitting width of the fixing bolt (not shown) can be ensured, and the fixing bolt can be prevented from loosening over a long period of time and the fixing force can be increased. Further, the vehicle body mounting flange 13 extends radially from the annular base portion 13a, and is divided into four to six (here, four) portions except for a portion except the vicinity of the fixing bolt insertion hole 17 (FIG. 2). reference). Thereby, the outer member 2 can be reduced in weight and size.

  Further, as shown in FIG. 4, a pilot member 18 fitted into the knuckle is integrally joined to the vehicle body mounting flange 13 by welding. The pilot member 18 is fitted in an inrow portion 19 formed on the inner side surface of the vehicle body mounting flange 13 via a predetermined fitting clearance. The centering accuracy between the pilot member 18 and the outer member 2 can be increased by the inrow portion 19.

  Between both rolling surfaces of the inner member 1 and the outer member 2, double rows of balls 3 and 3 are accommodated and held by the cages 20 and 20 so as to be freely rollable. Seals 21 and 22 are attached to the opening of the annular space formed between the inner member 1 and the outer member 2, and leakage of grease sealed inside the bearing and rainwater from the outside And dust are prevented from entering the bearing.

  The outer-side seal 21 is an integrated type composed of a core metal 23 press-fitted into the inner periphery of the outer-side end portion of the outer member 2 and a seal member 24 integrally joined to the core metal 23 by vulcanization adhesion. It is composed of a seal. The core metal 23 is formed by pressing an austenitic stainless steel plate (JIS standard SUS304 type or the like) or a cold rolled steel plate (JIS standard SPCC type or the like).

  On the other hand, the seal member 24 is made of synthetic rubber such as NBR (acrylonitrile-butadiene rubber), and is formed to be inclined to the side lip 24a and the dust lip 24b formed to be inclined outward in the radial direction, and to the inner side of the bearing. The grease lip 24c is integrally provided. The base portion 6c on the inner side of the flange portion 7 is formed in a curved surface having an arc-shaped cross section. The side lip 24a and the dust lip 24b are slidably contacted with the base portion 6c with a predetermined squeeze, and the grease lip 24c is A labyrinth seal is formed through the radial clearance.

  On the other hand, as shown in an enlarged view in FIG. 4, the inner side seal 22 is configured by a so-called pack seal including an annular seal plate 25 and a slinger 26 which are arranged to face each other. The seal plate 25 is composed of a core metal 27 press-fitted into the inner periphery of the end of the outer member 2 and a seal member 28 integrally joined to the core metal 27 by vulcanization adhesion. The core metal 27 is formed by pressing from a steel plate having rust prevention ability, such as an austenitic stainless steel plate (JIS standard SUS304 type or the like) or a rust-proof cold rolled steel plate (JIS standard SPCC type or the like). The cross section is substantially L-shaped.

  The seal member 28 is made of a synthetic rubber such as NBR, and includes a side lip 28a extending obliquely outward in the radial direction, a grease lip 28b and a dust lip 28c formed in a bifurcated shape.

  On the other hand, the slinger 26 is formed by pressing a steel plate having an antirust function such as an austenitic stainless steel plate (JIS standard SUS304 type or the like) or a rust-proof cold rolled steel plate (JIS standard SPCC type or the like). A cylindrical portion 26a that is formed in a substantially L-shaped cross section and is press-fitted into the shoulder portion 10 of the inner ring 5, and a standing plate portion 26b that extends radially outward from the cylindrical portion 26a. Then, the side lip 28a of the seal member 28 is slidably contacted with the upright plate portion 26b via a predetermined axial nip, and the grease lip 28b and the dust lip 28c are slid onto the cylindrical portion 26a via a predetermined radial nip. It is touched. Further, the standing plate portion 26b of the slinger 26 is opposed to the seal plate 25 through a slight radial clearance to form a labyrinth seal.

  As shown in FIG. 5, the hub wheel 4 is formed by pressing or cold rolling (hereinafter referred to as plastic working) a plate material or pipe material made of carburized steel such as SCr420 or SCM415 with a relatively small amount of carbon. ing. Specifically, it is formed from a pipe material by pressing and cold rolling. Further, both end faces where burrs are generated by plastic working are turned after the machining, or are ground if necessary. And the surface hardness is hardened in the range of 50 to 64 HRC by carburizing and quenching. Note that the caulking portion 4d is kept raw in raw material hardness by carburization prevention. Further, the inner rolling surface 4a is formed with a predetermined size and accuracy by grinding. Thereafter, superfinishing is performed as necessary. Thereby, it has sufficient mechanical strength with respect to the rotational bending load applied to the wheel mounting flange 6, the fretting resistance of the small diameter step portion 4c is improved, and the durability of the hub wheel 4 is further improved. Further, there is no occurrence of minute cracks and the like, and the plastic working of the crimped portion 4d can be performed smoothly.

  Here, as the material of the hub wheel 4, other than this, carburized steel such as SCM440, cold rolled steel plate (JIS standard SPCC system, etc.), and carbon steel such as S45C can be exemplified. In the case of cold rolled steel or carbon steel, the surface hardness is set to 50 to 50 by induction quenching from the inner rolling surface 4a to the small diameter step 4c from the base 6c which becomes the seal land part of the seal 21 on the outer side. A hardening process is performed in the range of 64 HRC.

  As shown in FIG. 6, the outer member 2 is formed by plastic working from a plate material and a pipe material made of carburized steel such as SCr420 and SCM415. Specifically, it is formed from a pipe material by pressing and cold rolling. And the surface hardness is hardened in the range of 50 to 64 HRC by carburizing and quenching. Other examples of the material of the outer member 2 include carburized steel such as SCM440, or cold rolled steel or carbon steel such as S45C. In the case of cold-rolled steel or carbon steel, at least the double row outer raceway surfaces 2a and 2a of the outer member 2 are hardened by induction hardening in a range of 50 to 64 HRC. The double row outer rolling surfaces 2a, 2a are formed with predetermined dimensions and accuracy by grinding. After that, superfinishing is performed as necessary.

  The inner ring 5 is formed by plastic working from a pipe material made of bearing steel such as SUJ2 or carburized steel such as SCr420 or SCM415. And the surface hardness is hardened in the range of 50 to 64 HRC by submerged quenching or carburizing quenching. Further, the inner rolling surface 5a is formed with a predetermined size and accuracy by grinding. After that, superfinishing is performed as necessary. In addition to this, examples of the material of the inner ring 5 include carburized steel such as SCM440, or cold rolled steel or carbon steel such as S45C. In the case of a cold rolled steel plate or carbon steel, at least the inner rolling surface 5a is subjected to a hardening process in a range of 50 to 64 HRC by induction hardening.

  As described above, in the present embodiment, the hub wheel 4, the inner ring 5, and the outer member 2 are formed by plastic working from a plate material or a pipe material, so that the strength and durability of the bearing can be improved with light weight and compactness. The illustrated wheel bearing device can be provided.

Furthermore, in this embodiment, the plate material or pipe material used as a raw material before plastic working is heated at a temperature equal to or lower than the A1 transformation point, and the plate-like Fe ₃ C (pearlite) in the structure is divided into spheroids, so-called spheroidization. Has been annealed. Thereby, a raw material softens and it becomes easy to carry out plastic working, and it can finish with high precision. In order to reduce the internal stress generated by plastic working, so-called stress-relief annealing is performed in which the sample is heated or soaked to an appropriate temperature and then cooled at an appropriate rate. Thereby, since the internal stress generated by the plastic working can be reduced, the deformation due to the heat treatment can be suppressed and the machining allowance for the subsequent grinding or the like can be reduced. Furthermore, since a machining allowance for grinding or the like is small, workability is improved, and strength can be increased by securing a wall thickness.

  FIG. 7 is a longitudinal sectional view showing a second embodiment of the wheel bearing device according to the present invention, and FIG. 8 is a side view of FIG. This embodiment basically differs from the above-described embodiment (FIG. 1) only in the configuration of the hub wheel and the outer member, and is the same for other parts and parts having the same function or the same function. Reference numerals are assigned and detailed description is omitted.

  This wheel bearing device is referred to as a third generation structure on the driven wheel side, and includes an inner member 29 and an outer member 30, and double-row balls 3, 3 accommodated between the members 29, 30 so as to roll freely. And. The inner member 29 includes a hub ring 31 and an inner ring 5 press-fitted into the hub ring 31.

  The hub wheel 31 integrally has a wheel mounting flange 32 for mounting the wheel W and the brake rotor BR at the outer end, and has one arc-shaped inner rolling surface 4a on the outer periphery, and the inner rolling surface. A cylindrical small-diameter step 4c extending in the axial direction from 4a through the shoulder 4b is formed. Hub bolts 6a are planted on the wheel mounting flange 32 in a circumferentially uniform manner.

  The wheel mounting flange 32 is divided into four to six (here, five) extending radially from the annular base 6c (see FIG. 8). The hub bolt insertion hole 7 is formed by punching, and the edge of the hub bolt insertion hole 7 protrudes by burring after the hub bolt insertion hole 7 is punched. As a result, the hub wheel 31 can be reduced in weight and size, and when the outer member 30 is fastened to the knuckle, the hub wheel 31 is not obstructed by the wheel mounting flange 32 and can be easily used with a tightening tool or the like. The fixing bolt can be fastened, and the assembling work can be simplified.

  The hub ring 31 is formed by plastic working from a pipe material made of carbon steel such as S45C. Further, both end faces where burrs are generated by plastic working are turned after the machining, or are ground if necessary. Then, the surface hardness is set in the range of 50 to 64 HRC by induction hardening from the inner rolling surface 4a to the small-diameter step portion 4c from the base portion 6c serving as the outer seal land portion. Note that the caulking portion 4d is kept as raw material hardness.

  Here, in the present embodiment, the outer edge portion of the wheel mounting flange 32 functions as a pilot portion of the brake rotor BR. That is, the cylindrical inner diameter portion 33 of the brake rotor BR is fitted on the outer edge portion of the wheel mounting flange 32 via a predetermined fitting clearance, and is guided in the radial direction with respect to the wheel mounting flange 32. This eliminates the need for a pilot portion as in the prior art, and can reduce the weight of the hub wheel 31.

  The inner edge 34 of the brake rotor BR is bent toward the inner side, and the inner edge 34 is in contact with the outer end of the wheel mounting flange 32. Thereby, when a large moment load is applied to the wheel mounting flange 32, deformation can be suppressed by the brake rotor BR, and the rigidity of the wheel mounting flange 32 can be increased.

  The outer member 30 is formed by plastic working from a pipe material made of carbon steel such as S45C, and integrally has a vehicle body mounting flange 35 to be attached to the knuckle K at the inner end portion, and is radially inward on the inner periphery. An annular convex portion 14 projecting in the direction, and double-row arc-shaped outer rolling surfaces 2 a and 2 a are integrally formed on both sides of the annular convex portion 14. In addition, fitting portions 15 and 16 serving as fitting portions for the seals 21 and 22 are formed at both end portions of the double row outer rolling surfaces 2a and 2a. The double row outer rolling surfaces 2a, 2a are subjected to hardening treatment by induction hardening in a range of surface hardness of 50 to 64 HRC.

  In the present embodiment, the fixing bolt insertion holes 17 are formed in the vehicle body mounting flange 35 at equal intervals in the circumferential direction by punching, and after the fixing bolt insertion holes 17 are punched, the fixing bolt insertion holes 17 are formed by burring. The edge is formed to protrude. The vehicle body mounting flange 13 extends radially from the outer diameter of the outer member 30 and is divided into four to six parts (here, five parts) by cutting out portions other than the vicinity of the fixing bolt insertion holes 17. (See FIG. 8). Thereby, the outer member 2 can be reduced in weight and size.

  Further, the inner peripheral end 30a on the inner side of the outer member 30 is formed into a predetermined dimension by turning and functions as a pilot portion of the knuckle K. That is, the cylindrical fitting portion 38 of the knuckle K is fitted into the end inner periphery 30a of the outer member 30 through a predetermined fitting clearance. As a result, the assembly to the knuckle K is improved, the contact surface with the knuckle K is increased, and when a large moment load is applied to the vehicle body mounting flange 35, deformation can be suppressed by the knuckle K, and the outer member The rigidity of 30 can be increased.

  Here, in this embodiment, in order to appropriately secure the shoulder height of the annular convex portion 14 from the outer rolling surface 2a, the inner diameter of the annular convex portion 14 is formed in a flat shape during plastic processing of the outer member 30. At the same time, the center part in the axial direction of the outer member 30 is recessed to form an annular recess 36 so that the shoulder 37 is filled with the material.

  And the curvature radius R of the connection part 36a of the outer diameter of the outward member 30 and the annular recessed part 36 is set so that it may become a predetermined range. Specifically, when the radius of the ball 3 is Rw, the radius of curvature R is set to be in a range of R = 1.5 to 2.5Rw. As a result, the thickness of this portion can be formed substantially evenly, and the shoulder portion 37 can be prevented from cracking, and the contact ellipse of the ball 3 rides on the shoulder portion 37 when a turning moment is applied, and the edge load is reduced. An appropriate shoulder height that can be prevented from occurring can be secured, and the durability of the bearing can be improved. Here, “substantially equal” means that the thickness of the pipe material before molding is uniform, and the thickness of the shape obtained as a result of molding without any plastic flow especially for the purpose of forming the connecting portion 36a other than the purpose of forming an arc. This means that a state where the thickness of the connecting portion 36a is slightly reduced or increased due to the displacement of the thickness of the material when forming the arc of the connecting portion 36a is included.

  When the radius of curvature R of the joint portion 36a is smaller than 1.5 times the radius Rw of the ball 3, the thickness is reduced and the rigidity is lowered, so that it cannot withstand the stress at the time of turning moment load. If it exceeds 2.5 times the thickness, not only will the wall thickness increase and the workability of plastic working will decrease, but the shape will not greatly differ from conventional forged products, and it will not contribute to light weight and compactness in general. is there.

  The embodiment of the present invention has been described above, but the present invention is not limited to such an embodiment, and is merely an example, and various modifications can be made without departing from the scope of the present invention. Of course, the scope of the present invention is indicated by the description of the scope of claims, and further, the equivalent meanings described in the scope of claims and all modifications within the scope of the scope of the present invention are included. Including.

  The wheel bearing device according to the present invention can be applied to a wheel bearing device including an inner member including a hub ring integrally having a wheel mounting flange and an inner ring press-fitted into the hub ring.

1, 29 Inner member 2, 30 Outer member 2a Outer rolling surface 3 Ball 4, 31 Hub wheel 4a, 5a Inner rolling surface 4b, 10, 37 Shoulder portion 4c Small diameter step portion 4d Caulking portion 5 Inner ring 6, 32 Wheel mounting flange 6a Hub bolt 6b Circular hole 6c, 13a Base portion 7 Bolt bolt insertion hole 8, 18 Pilot member 9, 19 Inrow portion 11 Large end portion 12 Small end portion 13, 35 Car body mounting flange 14 Annular convex portions 15, 16 Fitting Portion 17 Fixing bolt insertion hole 20 Cage 21 Outer side seal 22 Inner side seal 23, 27 Core metal 24, 28 Seal members 24a, 28a Side lip 24b, 28c Dustrip 24c, 28b Grease lip 25 Seal plate 26 Slinger 26a Cylindrical portion 26b Standing plate portion 33 Inner portion of brake rotor 34 Inner edge portion 36 of brake rotor Annular recess 36a DESCRIPTION OF SYMBOLS 50 Wheel bearing apparatus 51 Hub wheel 51a, 58a Inner rolling surface 52 Double row angular contact ball bearing 53 Shaft part 53a Small diameter step part 54, 61 Cut-and-raft piece 55, 62 Tongue piece 55a Expansion part 56 Hub bolt 57 Outer member 57a Outer rolling surface 58 Inner ring 59 Cage 60 Ball BR Brake rotor K Knuckle R Curvature radius Rw Ball radius

Claims (10)

An outer member in which a double-row arc-shaped outer rolling surface is integrally formed on the inner periphery;
A wheel mounting flange for mounting the wheel on the outer end is integrated, and an arcuate inner rolling surface facing one of the double row rolling surfaces on the outer periphery, and an axis extending from the inner rolling surface. A hub wheel formed with a cylindrical small-diameter step portion extending in the direction, and a circle that is press-fitted into the small-diameter step portion of the hub wheel through a predetermined shimoshiro and that opposes the other of the double-row outer rolling surfaces on the outer periphery An inner member composed of an inner ring formed with an arc-shaped inner rolling surface;
A double row of balls accommodated between the rolling surfaces of the inner member and the outer member via a retainer between the rolling surfaces;
A seal attached to an opening of an annular space formed between the outer member and the inner member;
In the wheel bearing device of the self-retained structure in which the inner ring is fixed in the axial direction with respect to the hub wheel by a crimping portion formed by plastically deforming an end portion of the small-diameter stepped portion radially outward.
The hub wheel and the inner ring and the outer member is formed by plastic working of the cold plate material or a pipe material, and the annular recess by recessing the axial center portion of the outer diameter of the outer member, the inner periphery, said double An annular convex portion protruding radially inward between the outer rolling surfaces of the row is formed in a flat shape, and a connecting portion between the outer diameter and the annular concave portion is formed in an arc shape having a predetermined radius of curvature, This part is set to a substantially uniform thickness, and the radius of curvature R of the joint is set to be in the range of R = 1.5 to 2.5 Rw, where Rw is the radius of the ball. A wheel bearing device characterized by that.   2. The hub bolt insertion holes are formed by punching at equal intervals in the circumferential direction of the wheel mounting flange, and the edge of the hub bolt insertion hole protrudes by burring after the hub bolt insertion holes are punched. The wheel bearing device described.   The fixing bolt insertion holes are formed by punching at equal intervals in the circumferential direction of the vehicle body mounting flange, and the edge of the fixing bolt insertion hole protrudes by burring after the fixing bolt insertion holes are punched. Item 3. A wheel bearing device according to Item 1 or 2.   The wheel mounting flange is formed in a circular shape, and a rib that extends radially from the annular base portion and is set to be slightly thick is formed on the inner side surface of the wheel mounting flange. The wheel bearing apparatus described in 1.   The wheel bearing device according to any one of claims 1 to 3, wherein the wheel mounting flange is formed by being divided into four to six extending radially from an annular base.   6. A cylindrical inner diameter portion of a brake rotor is externally fitted to an outer edge portion of the wheel mounting flange via a predetermined fitting clearance, and is guided in a radial direction with respect to the wheel mounting flange. The wheel bearing apparatus described in 1.   The wheel bearing device according to claim 6, wherein an inner edge portion of the brake rotor is formed by bending toward an inner side, and the inner edge portion is in contact with an end portion on the outer side of the wheel mounting flange.   The inner ring extends in the axial direction from the large-diameter side of the inner raceway surface, and has a cylindrical shoulder that serves as a fitting portion or a sliding contact portion of the inner-side seal, and radially inward from the shoulder. A large end portion formed by bending and a cylindrical small end portion extending in the axial direction from the small diameter side of the inner rolling surface, the small end portion butting the shoulder portion of the hub wheel in a state of abutting the small diameter The wheel bearing device according to claim 1, wherein the inner ring is fixed in the axial direction in a state in which the inner ring is pressed into the stepped portion and a predetermined bearing preload is applied by the caulking portion.   The wheel bearing device according to claim 1, wherein the plate material or the pipe material is heated at a temperature equal to or lower than the A1 transformation point before the plastic working, and the plate-like pearlite of the structure is divided and spheroidized and annealed.   The wheel bearing device according to claim 1, wherein the hub wheel is subjected to stress relief annealing in which the hub wheel is heated or soaked to a predetermined temperature before heat treatment and then cooled at a predetermined speed.

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