Method of manufacturing a joint member
By controlling the thickness deviation of the hardened layer during the hardening treatment of the raceway surface and guide groove of the joint component, the cracking problem during heat treatment was solved, and the lightweight and structural stability of the drive wheel bearing device was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JTEKT CORP
- Filing Date
- 2023-11-21
- Publication Date
- 2026-06-05
AI Technical Summary
When manufacturing the joint components of the bearing assembly for drive wheels, existing technologies struggle to suppress the axial dimension of the joint components while avoiding cracks during heat treatment, especially when the distance between the raceway surface and the guide groove is close.
The raceway surface and guide groove of the joint component are formed through a forming process. Then, in the hardening process, one of the raceway surface and guide groove is heated while the other is cooled to form a non-hardened layer, so as to control the thickness deviation of the hardened layer and prevent the generation of cracks.
It effectively suppressed the generation of cracks during heat treatment, achieved lightweight joint components, and ensured the stability and strength of the structure.
Smart Images
Figure CN122162006A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to a method for manufacturing a joint component. Background Technology
[0002] Patent Document 1 discloses a conventional bearing device for a drive wheel. This bearing device is a rolling bearing device for rotatably supporting a drive wheel, and has an integrated structure of rolling bearing and constant velocity universal joint. The rolling bearing consists of an outer ring, a hub ring equivalent to an inner ring, a drive shaft integrated with the inner ring, and rolling elements, etc. Meanwhile, the constant velocity universal joint consists of an outer joint member integrated with the drive shaft, an inner joint member, and balls, etc.
[0003] [Preliminary Technology Documents]
[0004] [Patent Documents]
[0005] [Patent Document 1] Japanese Patent Application Publication No. 2009-292275 Summary of the Invention
[0006] In vehicles powered by electric motors or internal combustion engines, there is a demand for extended driving range and improved electric or fuel economy. Therefore, lightweight drive wheel bearing assemblies are desired. The drive wheel bearing assembly described in Reference 1 eliminates the need for an inner ring by providing an inner ring raceway surface on the outer joint member (hereinafter referred to as the "joint member") of the constant velocity universal joint of the drive shaft. This structure is effective for weight reduction; however, further weight reduction is desired when designing such a drive wheel bearing assembly.
[0007] To achieve lightweighting of drive wheel bearing assemblies, a structure that effectively suppresses the axial dimension of the joint member is, for example, by providing a raceway surface on the outer surface of the joint member to guide the rolling elements circumferentially and a guide groove on the inner surface of the joint member to guide the balls axially. That is, the lightweighting of the joint member itself is effective. However, when this structure is adopted, the distance between the raceway surface and the guide groove of the joint member may become too close. To manufacture the joint member, the raceway surface and guide groove formed on the intermediate molded body need to be hardened by heat treatment. However, if the distance between the guide groove and the raceway surface is too close, the hardened layers formed by the heat treatment may connect, and a non-hardened layer may not be formed between them. Therefore, cracks may occur in the intermediate molded body during heat treatment. Therefore, when employing a structure that suppresses the axial dimension of the joint member, a technique is needed to prevent cracking during heat treatment.
[0008] This disclosure was made in view of the above-mentioned problems, and aims to provide a manufacturing method for manufacturing joint components that can suppress the generation of cracks during heat treatment.
[0009] [Technical Solution to the Problem]
[0010] One aspect of this disclosure is a method for manufacturing a joint member, the joint member comprising a bottom cylindrical portion and a connecting portion connected to a wheel hub mounted thereon in a manner capable of transmitting torque, wherein... The outer radial surface of the cylindrical portion is provided with a first inner raceway surface that guides a plurality of first rolling elements circumferentially. The inner radial surface of the cylindrical portion is provided with an outer guide groove that guides a plurality of third rolling elements axially. The manufacturing method has the following characteristics: The forming process will shape the intermediate forming body, preceding the joint component, into a shape having the first inner raceway surface and the outer guide groove; and The hardening process involves hardening both the first inner raceway surface and the outer guide groove of the intermediate molded body formed in the forming process. The hardening process is as follows: by heating either the first inner raceway surface or the outer guide groove while cooling the other, a non-hardened layer is formed between the hardened layer on the first inner raceway surface side and the hardened layer on the outer guide groove side.
[0011] [Invention Effects]
[0012] The joint component involved in manufacturing the above solution has the following structure: a first inner raceway surface is arranged radially outside the outer guide groove, overlapping at least a portion of the outer guide groove; or, the first inner raceway surface is arranged on a vertical line perpendicular to the tangent of the outer guide groove. This structure is effective in suppressing the axial dimension of the joint component to achieve weight reduction.
[0013] When manufacturing a joint component with this structure, in the hardening process following the forming process, a non-hardening layer is formed between the hardened layer on the first inner raceway side and the hardened layer on the outer guide groove side by heating either the first inner raceway surface or the outer guide groove. This hardening process suppresses deviations in the thickness of each hardened layer, and even if the distance between the first inner raceway surface and the outer guide groove is small, a non-hardening layer that is less prone to cracking can be formed between the two hardened layers.
[0014] According to the above scheme, a manufacturing method for joint components that can suppress the generation of cracks during heat treatment can be provided.
[0015] Furthermore, the reference numerals in parentheses in the claims indicate the correspondence with the specific means described in the following embodiments, and do not limit the technical scope of this disclosure. Attached Figure Description
[0016] The foregoing and other objects, features, and advantages of this disclosure will become more apparent from the following detailed description with reference to the accompanying drawings, which are shown below.
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[0037] Hereinafter, one embodiment of the above solution will be described with reference to the accompanying drawings.
[0038] In the accompanying drawings used to illustrate this embodiment, unless otherwise stated, the axial direction of the drive wheel bearing device and its constituent parts is designated as the X direction, the radial direction as the Y direction, the circumferential direction as the Z direction, and the direction around the axis as the D direction.
[0039] (Implementation Method 1)
[0040] 1. Overall structure of the drive wheel bearing assembly 1
[0041] like Figure 1 As shown, the drive wheel bearing assembly 1 of Embodiment 1 (hereinafter referred to as "bearing assembly") has a structure in which a constant velocity joint 1a and a rolling bearing 1b are integrated. This bearing assembly 1 is mounted on a vehicle driven by an electric motor or an internal combustion engine.
[0042] The constant velocity joint 1a is composed of multiple components, including an outer joint member 30, an inner joint member 41, multiple third balls 50 serving as multiple third rolling elements, and a cage 51. The constant velocity joint 1a is a joint with a fixed joint center, using the multiple third balls 50 as torque transmission components. The rolling bearing 1b is composed of multiple components, including an outer ring 10, a hub 20, an outer joint member 30, multiple first balls 60 serving as multiple first rolling elements, and multiple second balls 70 serving as multiple second rolling elements.
[0043] The outer ring 10 is generally cylindrical. On the inner circumferential surface of the outer ring 10, there are annular raceway surfaces 11 and 12 spaced apart in the axial direction X, arranged in two rows. Raceway surface 11 is for a plurality of first balls 60. Raceway surface 12 is for a plurality of second balls 70. The outer ring 10 is fixed to the vehicle body side member 2 by bolts (not shown). The vehicle body side member 2 is, for example, a member referred to as a "steering knuckle".
[0044] The hub 20 is formed in an annular shape. A connecting portion 35 of the outer joint member 30 is inserted into the inner circumference of the hub 20. Multiple bolts 22 are fixed on the hub 20, and the wheel 3, which serves as the drive wheel, is mounted on the hub 20 by the multiple bolts 22.
[0045] 2. Structure of the outer joint component 30
[0046] The outer joint member 30 is a component referred to as the outer race of the constant velocity universal joint 1a. The outer joint member 30 has a bottomed cylindrical portion (joint portion) 31 and a connecting portion 35 that is connected to the hub 20 in a manner capable of transmitting torque. The cylindrical portion 31 and the connecting portion 35 are integrated.
[0047] The cylindrical portion 31 of the outer connector member 30 is formed into a cup shape with a bottom surface. The cylindrical portion 31 and the hub 20 are fitted together at the fitting portion 36 by pressing in along the axial direction X. At this time, a gap can also be formed in the fitting portion 36 to a degree that can position the hub 20 and the outer connector member 30. The cylindrical portion 31 has an internal space 31a and an abutment surface 31b that abuts against the hub 20 along the axial direction X. The abutment surface 31b is formed at an intermediate position between a first inner raceway surface 33 provided on the cylindrical portion 31 and a second inner raceway surface 21 provided on the hub 20. That is, with respect to the abutment surface 31b, the first inner raceway surface 33 is positioned closer to the axle 40 than the abutment surface 31b, and the second inner raceway surface 21 is positioned closer to the wheel 3 than the abutment surface 31b. Therefore, with the imaginary plane (not shown) of the abutment surface 31b sandwiched in the middle, the first ball 60 is positioned on one side of the axial direction X, and the second ball 70 is positioned on the other side of the axial direction X. Furthermore, the abutment surface 31b is configured to overlap with the inner space 31a in the radial direction Y, i.e., within the axial direction X range of the inner space 31a. This configuration of the abutment surface 31b effectively reduces the length of the connecting portion 35 of the outer connector member 30 in the axial direction X.
[0048] On the inner surface of the cylindrical portion 31 of the outer connector member 30 in the radial direction Y, a plurality of outer guide grooves 32 are provided to guide a plurality of third balls 50 in the axial direction X. The plurality of outer guide grooves 32 are formed at equal intervals in the circumferential direction Z of the cylindrical portion 31. The first inner raceway surface 33 is provided on the outer surface of the cylindrical portion 31 of the outer connector member 30 in the radial direction Y in order to guide the plurality of first balls 60 in the circumferential direction Z. The first inner raceway surface 33 is formed in an annular shape in the circumferential direction Z of the cylindrical portion 31.
[0049] The connecting portion 35 of the outer connector member 30 engages with the hub 20 via a so-called "spline engagement" (a structure in which the protruding teeth of the spline shaft engage with the grooves of the spline hole), and is fastened to the hub 20 by bolts 23. That is, the external thread provided on the shaft portion 23b extending from the head 23a of the bolt 23 engages with the internal thread provided in the recess 35a of the connecting portion 35.
[0050] 3. Structure of the inner joint component 41
[0051] The inner joint member 41 is formed in a ring shape and fixed to the outer periphery of the shaft 40 connected to the vehicle's drive source (electric motor or internal combustion engine). The inner joint member 41 is housed within the internal space 31a of the cylindrical portion 31 of the outer joint member 30. The inner joint member 41 is tiltable relative to the outer joint member 30 with a predetermined universal joint center point P as its center. In this embodiment, the angle formed by the central axis L1 of the outer joint member 30 and the central axis L2 of the inner joint member 41 is called the universal joint angle. Furthermore, Figure 1 This shows the state where the universal joint angle is zero degrees.
[0052] 4. Structure of the third ball bearing 50
[0053] The plurality of third balls 50 are spheres of the same shape. The plurality of third balls 50 are housed within the internal space 31a of the cylindrical portion 31 of the outer connector member 30. The plurality of third balls 50 function to connect the cylindrical portion 31 of the outer connector member 30 to the inner connector member 41 in a manner capable of transmitting torque. One outer guide groove 32 guides one third ball 50. The number of outer guide grooves 32 and third balls 50 is six or eight.
[0054] 5. Structure of the first ball bearing 60
[0055] like Figure 1 and Figure 2 As shown, the plurality of first balls 60 are spheres of the same shape. The plurality of first balls 60 are disposed between the raceway surface 11 of the outer ring 10 and the first inner raceway surface 33 of the outer connector member 30. The plurality of first balls 60 support the outer ring 10 and the outer connector member 30 such that they can be positioned in the axial direction D (refer to...) Figure 1 The function of relative rotation on the upper surface. The number of the first ball bearings 60 is not limited to... Figure 2 As shown, the appropriate quantity can be set.
[0056] 6. Structure of the second ball bearing 70
[0057] like Figure 1 and Figure 3 As shown, the plurality of second balls 70 are spheres of the same shape. The plurality of second balls 70 are disposed between the raceway surface 12 of the outer ring 10 and the second inner raceway surface 21 of the hub 20. The plurality of second balls 70 support the outer ring 10 and the hub 20 such that they can be positioned in the axial direction D (refer to...). Figure 1 The second inner raceway surface 21 is provided on the radial Y outer surface of the hub 20 in a manner that overlaps with the internal space 31a of the cylindrical portion 31 in order to guide a plurality of second balls 70 in the circumferential direction Z. The second inner raceway surface 21 is formed in an annular shape in the circumferential direction Z of the hub 20. The number of second balls 70 is not limited to... Figure 2 As shown, the appropriate quantity can be set.
[0058] In addition to spheres, the first ball 60 and the second ball 70 can also be cylindrical rollers, needle-shaped needle rollers, or conical rollers.
[0059] like Figure 4As shown, each third ball 50 contacts the outer guide groove 32 at two contact positions 32a in the circumferential direction. A small gap is formed between the bottom 32b of the outer guide groove 32 between the two contact positions 32a and the third ball 50. The surface between two adjacent outer guide grooves 32 is formed by the inner spherical surface 34 of the connector.
[0060] 7. Structure of cage 51
[0061] like Figure 5 As shown, the retainer 51 is formed in a cylindrical shape to hold a plurality of third balls 50. The outer and inner peripheral surfaces of the retainer 51 are spherical and are clamped and disposed between the inner spherical surface 34 of the connector provided on the cylindrical portion 31 of the outer connector member 30 and the outer spherical surface 42 of the connector provided on the inner connector member 41.
[0062] 8. Lightweight structure of the drive wheel bearing assembly 1
[0063] Next, refer to Figures 5 to 15 The lightweight structure characteristic of the bearing device 1 of this embodiment will be described. The bearing device 1 has no other components (e.g., components referred to as "inner rings" or "hub inner rings") between the outer joint member 30 and the plurality of first balls 60, which is beneficial for lightweighting. To achieve further lightweighting, the bearing device 1 of this embodiment includes the following first to eighth lightweight structures.
[0064] 8-1. First Lightweight Structure
[0065] like Figure 5 As shown, the first lightweight structure is as follows: In the outer joint member 30, the first inner raceway surface 33 is arranged on the outer side of the outer guide groove 32 in a radial Y direction, such that at least a portion of the first inner raceway surface 33 overlaps with the outer guide groove 32. Figure 5 For ease of explanation, the region of the outer guide groove 32 extending along the axial direction X is represented as shaded region A, and the region of the first inner raceway surface 33 extending along the arc surface is represented as shaded region B. In this embodiment, region B of the first inner raceway surface 33 extending along the arc surface completely overlaps with region A of the outer guide groove 32 extending along the axial direction X in the radial direction Y. Alternatively, a portion of region B may also overlap with region A in the radial direction Y.
[0066] According to the first lightweight structure, compared with the existing structure, a narrow structure can be achieved that allows the outer guide groove 32 to approach the first inner raceway surface 33 in the axial X direction. In this case, the dimension of the connecting portion 35 of the outer joint member 30 in the axial X direction can be shortened. As a result, the bearing assembly 1 can be made lighter.
[0067] 8-2. Second Lightweight Structure
[0068] like Figure 6 As shown, the second lightweight structure is as follows: In the outer joint member 30, the first inner raceway surface 33 is positioned on a vertical line L4 perpendicular to the tangent L3 of the outer guide groove 32. The tangent L3 is typically the bottom 32b of the outer guide groove 32 (see reference). Figure 4 The tangent at () is also possible at the contact position 32a relative to the outer guide groove 32 (see reference). Figure 4 The tangent to the trajectory of the ball, or the tangent to the trajectory relative to the center of the third ball 50.
[0069] According to the second lightweight structure, similar to the first lightweight structure, the dimension of the connecting portion 35 of the outer joint member 30 in the axial direction X can be shortened, thereby making the bearing device 1 lighter.
[0070] 8-3. Third Lightweight Structure
[0071] like Figure 7 As shown, the third lightweight structure is as follows: In the outer joint member 30, the angle θa between the imaginary straight line L5 and the central axis L1 of the outer joint member 30 is 60 to 80 degrees. The imaginary straight line L5 is a straight line that virtually connects the universal joint center point P of the inner joint member 41 and the center Q2 of the first ball 60.
[0072] According to the third lightweight structure, similar to the first lightweight structure, the dimension of the connecting portion 35 of the outer joint member 30 in the axial direction X can be shortened, thus enabling the bearing assembly 1 to be lightweight. In particular, the larger the angle θa is set, the greater the lightweight effect of the bearing assembly 1.
[0073] 8-4. Fourth Lightweight Structure
[0074] like Figure 7 As shown, the fourth lightweight structure is as follows: In the outer joint member 30, in the state where the universal joint angle is zero degrees ( Figure 1 In the state of (the above), the angle θb between the imaginary straight line L6 and the central axis L1 of the outer connector component 30 is set to 35 to 75 degrees. The imaginary straight line L6 is a straight line that virtually connects the center Q1 of the third ball 50 and the center Q2 of the first ball 60.
[0075] According to the fourth lightweight structure, similar to the first lightweight structure, the dimension of the connecting portion 35 of the outer joint member 30 in the axial direction X can be shortened, thus enabling the bearing assembly 1 to be lightweight. In particular, the larger the angle θb is set, the greater the lightweight effect of the bearing assembly 1.
[0076] 8-5. Fifth Lightweight Structure
[0077] like Figure 8 As shown, the fifth lightweight structure is as follows: In a stable state where the universal joint angle is within its normal range, the third ball 50 contacts the cylindrical portion 31 of the outer joint member 30 at contact range C, and contact range C is positioned on a vertical line L8 perpendicular to the tangent L7 of the first inner raceway surface 33. The stable state referred to here means when the vehicle is stopped or moving straight. Tangent L7 is the tangent at the contact point between the first inner raceway surface 33 and the third ball 50. Figure 8 In the diagram, for ease of explanation, the contact area C is represented as the shaded region.
[0078] According to the fifth lightweight structure, similar to the first lightweight structure, the dimension of the connecting portion 35 of the outer joint member 30 in the axial direction X can be shortened, thereby making the bearing device 1 lighter.
[0079] 8-6. Sixth Lightweight Structure
[0080] like Figure 9 As shown, the sixth lightweight structure is as follows: the angle θc between the imaginary straight line L9 and the central axis L1 of the outer joint member 30 is set to 40 to 60 degrees. The imaginary straight line L9 is a straight line that virtually connects the universal joint center point P of the inner joint member 41 and the center Q3 of the second ball 70.
[0081] According to the sixth lightweight structure, similar to the first lightweight structure, the dimension of the connecting portion 35 of the outer joint member 30 in the axial direction X can be shortened, thus enabling the bearing assembly 1 to be lightweight. In particular, the larger the angle θc is set, the greater the lightweight effect of the bearing assembly 1.
[0082] 8-7. Seventh Lightweight Structure
[0083] like Figure 9 As shown, the seventh lightweight structure is as follows: in the state where the universal joint angle is zero degrees ( Figure 1 In the state of (the above), the angle θd between the imaginary straight line L10 and the central axis L1 of the outer connector component 30 is set to 15 to 55 degrees. The imaginary straight line L10 is a straight line that virtually connects the center Q1 of the third ball 50 and the center Q3 of the second ball 70.
[0084] According to the seventh lightweight structure, similar to the first lightweight structure, the dimension of the connecting portion 35 of the outer joint member 30 in the axial direction X can be shortened, thus enabling the bearing assembly 1 to be lightweight. In particular, the larger the angle θd is set, the greater the lightweight effect of the bearing assembly 1.
[0085] 8-8. Eighth Lightweight Structure
[0086] The eighth lightweight structure reduces the weight of the bearing assembly 1 by reducing the radial Y thickness of the cylindrical portion 31 of the outer joint member 30. For this eighth lightweight structure, refer to... Figures 10 to 15 .
[0087] Figure 10 and Figure 11 The diagram shows the bearing assembly 1 in a straight-line driving state when wheel 3 is the right front wheel. This state is a stable state with the universal joint angle α within a commonly used range (e.g., approximately 6 degrees), and the inner joint member 41 is positioned, for example, in the first position R1. The same applies when the vehicle is parked. In contrast, Figure 12 and Figure 13 The diagram shows the bearing assembly 1 in a left-turning state when wheel 3 is the right front wheel. This state is a variable state in which the universal joint angle α becomes a value exceeding the normal range (e.g., a value of up to about 25 degrees), and the inner joint member 41 is, for example, configured in the second position R2.
[0088] like Figure 11 and Figure 13 As shown, the eighth lightweight structure is as follows: in the cross-section containing the central axes L1 and L2 of the outer joint member 30 and the inner joint member 41, the condition that the inner contact direction Ea and the outer contact direction Eb are inconsistent is satisfied. That is, not only are the inner contact direction Ea and the outer contact direction Eb inconsistent in three dimensions, but they are also inconsistent when viewed in two dimensions in the above cross-section.
[0089] The inner contact direction Ea is the contact direction of the first ball 60 on the first inner raceway surface 33 in the cylindrical portion 31 of the outer connector member 30. The first ball 60 is in contact position 33a (at... Figure 11 and Figure 13 In the region (represented by a roughly elliptical cross section), a contact angle β (an angle relative to an imaginary straight line of radial Y) is applied to the first inner raceway surface 33, and a load in the inner contact direction Ea is applied to this first inner raceway surface 33. The contact angle β is, for example, approximately 40 degrees during straight travel (refer to...). Figure 11 When turning left, for example, it is about 52 degrees (see reference). Figure 13 At this time, stress corresponding to the load input from the first ball 60 is generated on the first inner raceway surface 33 of the cylindrical portion 31. The inner contact direction Ea can also be referred to as the load input direction from the first ball 60.
[0090] Furthermore, the outer contact direction Eb is the contact direction of the third ball 50 on the outer guide groove 32 in the cylindrical portion 31 of the outer connector member 30. Regarding the third ball 50, when the universal joint angle is α, the center of the third ball 50 is located on a straight line passing through the universal joint center point P and inclined from a plane perpendicular to the central axis L1 by 1 / 2 of the universal joint angle α, i.e., α / 2, passing through the universal joint center point P, and at the contact position 32a (in... Figure 11 and Figure 13 In the region (represented by a roughly elliptical cross-section), the outer guide groove 32 is contacted with a contact angle γ (an angle relative to an imaginary straight line of radial Y) greater than α / 2, and a load in the outer contact direction Eb is input to the outer guide groove 32. At this time, stress corresponding to the load input from the third ball 50 is generated on the outer guide groove 32 of the cylindrical portion 31. The outer contact direction Eb can also be referred to as the load input direction from the third ball 50.
[0091] Here, assuming that the inner contact direction Ea and the outer contact direction Eb are aligned, it is foreseeable that localized stress concentration will occur in the cylindrical portion 31 of the outer joint member 30 where the inner contact direction Ea and the outer contact direction Eb are aligned. If the thickness of the cylindrical portion 31 is increased to withstand this stress concentration, the weight of the bearing assembly 1 may increase. Therefore, in the eighth lightweight structure, by making the inner contact direction Ea and the outer contact direction Eb not aligned, the aforementioned stress concentration in the cylindrical portion 31 of the outer joint member 30 is suppressed. As a result, the thickness of the cylindrical portion 31 can be suppressed, and the bearing assembly 1 can be made lighter.
[0092] like Figure 11 and Figure 13 As shown, when the extension line extending from the center of the first ball 60 along the inner contact direction Ea is designated as the first extension line M1, multiple such first extension lines M1 are formed depending on the number of first balls 60. Here, the first extension line M1 is a line that directly connects the center of the first ball 60 to the contact position 33a of the first ball 60 in the first inner raceway surface 33. Furthermore, when the extension line extending from the center of the third ball 50 along the outer contact direction Eb is designated as the third extension line M3, multiple such third extension lines M3 are formed depending on the number of third balls 50. Here, the third extension line M3 is a line that directly connects the center of the third ball 50 to the contact position 32a of the third ball 50 in the outer guide groove 32.
[0093] The eighth lightweight structure preferably satisfies the following conditions: when multiple first extension lines M1 include a line passing through the contact position 32a of the third ball 50 in the outer guide groove 32, the third extension line M3 of the third ball 50 at the contact position 32a does not pass through the contact position 33a of the first ball 60 in the first inner raceway surface 33; and when multiple third extension lines M3 include a line passing through the contact position 33a of the first ball 60 in the first inner raceway surface 33, the first extension line M1 of the first ball 60 at the contact position 33a does not pass through the contact position 32a of the third ball 50 in the outer guide groove 32.
[0094] Regarding this structure, for example, Figure 14 As shown, although one of the three first extension lines M1 passes through the contact position 32a of the third ball 50 in the outer guide groove 32, the third extension line M3 at that contact position 32a with respect to the third ball 50 does not pass through the contact position 33a of any of the first balls 60 in the first inner raceway surface 33. Furthermore, although one third extension line M3 passes through the contact position 33a of the first balls 60 in the first inner raceway surface 33, the first extension line M1 at that contact position 33a with respect to the first balls 60 does not pass through the contact position 32a of any of the third balls 50 in the outer guide groove 32.
[0095] Furthermore, the eighth lightweight structure preferably satisfies the following condition: when turning at a universal joint angle α exceeding the usual range (refer to...). Figure 12 and Figure 13 The first extension line M1 of the first ball 60 with the largest input load on the first inner raceway surface does not pass through the contact position 32a in the outer guide groove 32 of any of the multiple third balls 50.
[0096] Regarding this structure, for example, Figure 15 As shown, when the upper part of the figure is defined as the upper part of the vehicle, the first ball 60 at the highest position (first position S1) among the three first balls 60 bears the largest load F from the vehicle side compared to the first balls 60 at lower positions (second position S2 or third position S3). Therefore, the first ball 60 at the first position S1 has the largest input load on the first inner raceway surface 33 among the three first balls 60. At this time, the first extension line M1 of the first ball 60 at the first position S1 does not pass through the contact position 32a in the outer guide groove 32 of any of the multiple third balls 50.
[0097] 9. Manufacturing method of the outer joint component 30
[0098] like Figure 16As shown, the outer connector component 30 is manufactured by sequentially performing a forming process S101, a hardening process S102, and a post-processing process S103. Additional processes may be added to these processes as needed, or at least one process may be divided into multiple processes.
[0099] Forming process S101 is a process in which an intermediate forming body, which will become the outer joint member 30, is formed into a shape having a first inner raceway surface 33 and an outer guide groove 32. Although not specifically illustrated, a known forging apparatus is used in this forming process S101. The material for the intermediate forming body can be, for example, carbon steel for mechanical structures (S55C).
[0100] like Figure 17 As shown, the hardening process S102 is a process of hardening both the first inner raceway surface 33 and the outer guide groove 32 of the intermediate molded body W formed by the forming process S101. In this hardening process S102, either the first inner raceway surface 33 or the outer guide groove 32 of the intermediate molded body W is heated while the other is cooled. This hardening process S102 includes the first step S102a and the second step S102b, which will be described later.
[0101] Post-processing step S103 is a process of post-processing the intermediate molded body W that has undergone hardening treatment step S102. This post-processing step S103 includes known processes such as tempering, machining, threading, and painting.
[0102] In this embodiment, in order to achieve a lighter bearing device 1 by reducing the weight of the outer joint member 30, a structure is adopted to suppress the axial X dimension of the outer joint member 30. Therefore, as Figure 17 As shown, the distance d between the first inner raceway surface 33 and the outer guide groove 32 of the intermediate molded body W becomes closer. That is, the thickness of the portion between the first inner raceway surface 33 and the outer guide groove 32 in each part of the intermediate molded body W becomes thinner. If the distance d between the first inner raceway surface 33 and the outer guide groove 32 is close, cracks may occur in the intermediate molded body W during heat treatment. Therefore, in this embodiment, a hardening treatment step S102, which is effective in solving this problem, is performed.
[0103] like Figure 18 As shown, the first step S102a of the hardening process S102 is as follows: while heating the first inner raceway surface 33 of the intermediate formed body W, the outer guide groove 32 is cooled, and then, immediately after heating, the first inner raceway surface 33 is cooled. In the first step S2a, as an example, a high-frequency quenching device 80, a cooling device 90, and a cooling device 91 (see reference...) are used. Figure 19The high-frequency quenching device 80 is used to heat the first inner raceway surface 33 from the outside. The cooling device 90 is used to cool the outer guide groove 32 from the inside. The cooling device 91 is used to cool the first inner raceway surface 33 from the outside immediately after the heating by the high-frequency quenching device 80 is completed.
[0104] The high-frequency quenching apparatus 80 has a heating section 80a, which surrounds the outside along the circumferential direction Z (see reference). Figure 6 The first inner raceway surface 33 is extended. The heating section 80a has a known structure and has the function of heating the first inner raceway surface 33 by generating eddy currents in a coil through which a magnetic force m is generated by passing a high-frequency induced current. According to this high-frequency quenching apparatus 80, the first inner raceway surface 33 of the intermediate formed body W is selectively heated from the outside.
[0105] The cooling device 90 is a nozzle extending along the axial direction X, and a plurality of spray nozzles 90a for spraying coolant CL are provided on the outer peripheral surface of the nozzle. The cooling device 90 is inserted into the internal space 31a with the plurality of spray nozzles 90a facing the outer guide groove 32 of the intermediate molded body W, and sprays coolant CL through the plurality of spray nozzles 90a. Water or oil can be used as the coolant CL. According to this cooling device 90, the outer guide groove 32 of the intermediate molded body W is selectively cooled from the inside.
[0106] like Figure 19 As shown, the cooling device 91 is a cooling jacket that surrounds the first inner raceway surface 33 from the outside. Multiple nozzles 91a for spraying coolant CL are provided on the inner circumferential surface of the cooling jacket. The cooling device 91 replaces the high-frequency quenching device 80, and with the multiple nozzles 91a arranged opposite to the outer guide groove 32 of the intermediate formed body W, coolant CL is sprayed through the multiple nozzles 91a. According to this cooling device 91, the first inner raceway surface 33 is rapidly cooled immediately after heating, forming a hardened layer t1 on the surface side of the first inner raceway surface 33 (see reference). Figure 20 ).
[0107] like Figure 19 As shown, the second step S102b of the hardening process S102 is as follows: after performing the first step S102a, the first inner raceway surface 33 is cooled while the outer guide groove 32 of the intermediate formed body W is heated; then, the outer guide groove 32 is cooled immediately after heating. In the second step S102b, as an example, a high-frequency quenching device 81 for heating the outer guide groove 32 from the inside, as well as the aforementioned cooling device 91 and cooling device 90 (see reference...) Figure 18 ).
[0108] The high-frequency quenching apparatus 81 has a heating section 81a arranged opposite to the outer guide groove 32. Similar to the heating section 80a of the high-frequency quenching apparatus 80, the heating section 81a has the function of heating the outer guide groove 32 by inducing eddy currents in a coil that generates magnetic force m by passing a high-frequency induced current through it. According to this high-frequency quenching apparatus 81, the outer guide groove 32 of the intermediate formed body W is selectively heated from the inside. Afterwards, the outer guide groove 32 is rapidly cooled by the cooling device 90 immediately after heating, forming a hardened layer t2 (see reference) on the surface side of the outer guide groove 32. Figure 20 ).
[0109] like Figure 20 As shown, according to the hardening process S102, a hardened layer t1 is formed on the first inner raceway surface 33 side of the intermediate forming body W, a hardened layer t2 is formed on the outer guide groove 32 side, and a non-hardened layer t3 is formed between the hardened layer t1 and the hardened layer t2.
[0110] The unhardened layer t3 can be a layer composed solely of the base material, or a layer comprising a layer composed of the base material and a low-hardness layer with a hardness exceeding that of the base material but lower than that of the hardened layers t1 and t2, or a layer composed solely of the aforementioned low-hardness layers. For example, when the Vickers hardness of the first inner raceway surface 33 and the outer guide groove 32 is 700–800 [HV], and the Vickers hardness of the base material is 200–250 [HV], the target value of the Vickers hardness of the hardened layers t1 and t2 is preferably 500 [HV] or higher, and the target value of the Vickers hardness of the unhardened layer t3 is preferably lower than 500 [HV]. The Vickers hardness is based on JIS Z2244 (2009).
[0111] In the hardening process S102, it is preferable to harden both the first inner raceway surface 33 and the outer guide groove 32, such that the thickness d3 of the unhardened layer t3 is greater than 0 mm and less than 2 mm. For example, when the distance d between the first inner raceway surface 33 and the outer guide groove 32 is approximately 8 mm, considering the deviation in the actual quenching depth achieved by the high-frequency quenching devices 81 and 82, the target value of the quenching depth can be set such that the thickness d1 of the hardened layer t1 and the thickness d2 of the hardened layer t2 are both approximately 3 mm. The setting of the target value of the quenching depth can be changed, for example, by adjusting the output of the high-frequency quenching devices 81 and 82.
[0112] 10. Effects
[0113] According to the above-described embodiment 1, the following effects can be obtained.
[0114] The outer joint member 30 of the bearing device 1 constituting Embodiment 1 has the following structure: the first inner raceway surface 33 is arranged on the outer side of the radial Y direction of the outer guide groove 32 in such a way that at least a portion of the first inner raceway surface 33 overlaps with the outer guide groove 32; or, the first inner raceway surface 33 is arranged on a vertical line L4 perpendicular to the tangent L3 of the outer guide groove 32. This structure is effective in reducing the axial X dimension of the outer joint member 30 to achieve weight reduction. Furthermore, this structure can also be said to satisfy the condition that the inner contact direction Ea of the first ball 60 in the first inner raceway surface 33 is not consistent with the outer contact direction Eb of the third ball 50 in the outer guide groove 32.
[0115] When manufacturing the outer connector member 30 with this structure, in the hardening process S102 following the forming process S101, a non-hardening layer t3 is formed between the hardened layer t1 on the first inner raceway surface 33 side and the hardened layer t2 on the outer guide groove 32 side by heating one of them and cooling the other. This hardening process suppresses deviations in the thickness of each hardened layer, and even if the distance d between the first inner raceway surface 33 and the outer guide groove 32 is close, a non-hardening layer t3 that is less prone to cracking can be formed between the two hardened layers t1 and t2.
[0116] As described above, according to Embodiment 1, a lightweight joint member 30 can be manufactured while suppressing cracking of the intermediate formed body W during heat treatment. Furthermore, with the lightweighting of the joint member 30, the bearing assembly 1 can be lightweighted. As a result, the driving range of a vehicle equipped with the bearing assembly 1 can be extended, or its electric or fuel economy can be improved.
[0117] According to Embodiment 1, in the hardening process S102, the cooling of either the first inner raceway surface 33 or the outer guide groove 32 is carried out by spraying coolant CL, thereby enabling the equipment involved in cooling to be universalized and the equipment cost to be kept low.
[0118] According to Embodiment 1, in the hardening process S102, by setting the thickness d3 of the unhardened layer t3 to be greater than 0 [mm] and less than 2 [mm], it is possible to set the unhardened layer t3 between the two hardened layers t1 and t2 while keeping the distance between the first inner raceway surface 33 and the outer guide groove 32 as small as possible.
[0119] 11. Deformation Method
[0120] This disclosure is based on the above-described form, but it should be understood that this disclosure is not limited to this form or structure. This disclosure also includes various modifications and equivalent variations. Furthermore, various combinations and forms, and even combinations and forms containing only one element, or more or less, also fall within the scope and concept of this disclosure.
[0121] In the above embodiment, an example is illustrated where, in the hardening process S102, a first step S102a is performed first, heating the first inner raceway surface 33 before heating the outer guide groove 32, and then a second step S102b is performed to heat the outer guide groove 32. However, alternatively, the second step S102b may be performed before the first step S102a. In this case, Figure 16 The second step S102b becomes the "first step". Figure 16 The first step S102a becomes the "second step".
[0122] In the above embodiments, the structures of the high-frequency quenching devices 81 and 82 for heating and the cooling devices 90 and 91 for cooling are not limited to the above structures and can be modified as needed.
Claims
1. A method for manufacturing a connector member (30) (S101-S103), the connector member (30) comprising a cylindrical portion (31) with a bottom cylindrical shape and a connecting portion (35) connected to a wheel hub on which a wheel is mounted in a manner capable of transmitting torque, wherein, The outer surface of the cylindrical portion in the radial (Y) direction is provided with a first inner raceway surface (33) that guides a plurality of first rolling elements (60) in the circumferential (Z) direction. An outer guide groove (32) is provided on the inner surface of the cylindrical portion in the radial direction (Y) to guide a plurality of third rolling elements (50) in the axial direction (X). The manufacturing method has the following characteristics: The forming process (S101) forms the intermediate forming body (W) before the joint member into a shape having the first inner raceway surface and the outer guide groove. as well as The hardening process (S102) hardens both the first inner raceway surface and the outer guide groove of the intermediate molded body formed by the forming process. The hardening process is as follows: by heating one of the first inner raceway surface and the outer guide groove while cooling the other, a non-hardened layer (t3) is formed between the hardened layer (t1) on the first inner raceway surface side and the hardened layer (t2) on the outer guide groove side.
2. The method for manufacturing a joint component according to claim 1, wherein, The first inner raceway surface is arranged on the outer side of the radial (Y) direction of the outer guide groove in such a way that the first inner raceway surface overlaps with at least a portion of the outer guide groove, or the first inner raceway surface is arranged on a vertical line (L4) that is perpendicular to the tangent (L3) of the outer guide groove.
3. The method for manufacturing the joint component according to claim 1 or 2, wherein, The hardening process includes: In the first step (S102a), the outer guide groove is cooled while the first inner raceway surface is heated, and then the first inner raceway surface is cooled immediately after the heating is completed; and The second step (S102b) involves heating the outer guide groove while simultaneously cooling the first inner raceway surface, and then immediately cooling the outer guide groove after the heating is completed.
4. The method for manufacturing the joint component according to claim 1 or 2, wherein, The hardening process includes: In the first step (S102a), the first inner raceway surface is cooled while the outer guide groove is heated, and then the outer guide groove is cooled immediately after heating is completed; and The second step (S102b) involves heating the first inner raceway surface while simultaneously cooling the outer guide groove, and then immediately cooling the first inner raceway surface after the heating is completed.
5. The method for manufacturing the joint component according to claim 1 or 2, wherein, Cooling of either the first inner raceway surface or the outer guide groove is achieved by spraying coolant (CL).
6. The method for manufacturing a joint component according to claim 1 or 2, wherein, In the hardening process, the thickness (d3) of the unhardened layer is set to be greater than 0 mm and less than 2 mm.