Method for assembling at least one bearing ring cooperating with shrink-fitting object surface of component in shrink-fitting

Abstract

To provide an assembling method for assembling at least one bearing ring to a component, while preventing degradation of linearity of a spline of the component and securing perfect torque transmission between a transmission portion and the component.SOLUTION: A method for assembling at least one bearing ring cooperating with shrink-fitting surface 110 of a component 100 in shrink-fitting includes: a process for forming a spline 103 extending in an axial direction on an inner wall of the component 100; a process for shrink-fitting the bearing ring to the shrink-fitting object surface 110 of the component 100 in a manner that a lower transverse face of the bearing ring comes into abutment against a shoulder portion 105 of the component 100; and a process for enlarging diameters of a part of the spline 103 and the shrinking-fitting object surface 110 by elastoplastic expansion of an upper region of the component 100 in a radial direction after the process for forming the spline 103 before the process for shrink-fitting the bearing ring to the shrink-fitting object surface 110 of the component 100.SELECTED DRAWING: Figure 7

Description

Technical Field

[0005]

[0001] The present invention generally relates to the technical field of assembling mechanical parts.

[0002] More specifically, the present invention relates to the assembly of parts such as a drive wheel hub of a vehicle with a transmission bowl-shaped body.

Background Art

[0003] Generally, the rotation of a hub on a wheel spindle is performed using a bearing. In most cases, this bearing consists of an outer ring, a double row of rolling elements, and at least one inner ring fitted to the hub so as to axially contact the shoulder portion of the bearing surface of the hub.

[0004] One row of rolling elements rolls between one of the rolling surfaces of the outer ring and the rolling surface of the inner ring. The other row of rolling elements rolls between the other of the rolling surfaces of the outer ring and the rolling surface of the hub or the rolling surface of the second inner ring. The so-called inner ring is the one that is fitted to the hub.

[0005] In any form, the inner ring is radially fixed to the hub by fitting. Also, one end in the axial direction of the bearing is fixed by pressing against the shoulder portion of the hub, and the other end in the axial direction is fixed by an annular flange portion formed by plastically deforming the portion of the hub where the inner ring to be maintained is attached, or, in some cases, by a transmission bowl-shaped body. By pressing the pressing surface of this flange portion or the transmission bowl-shaped body against the upper surface of the race ring, the race ring is axially pressed against the shoulder portion of the bearing surface of the hub and axially fixed. After the formation of the flange portion and the tightening and fixing of the transmission portion, and by ensuring the axial holding of the inner ring by this flange portion or the transmission bowl-shaped body, the assembled product becomes usable.

[0006] The hub of the wheel consists of a part having an axially hollow portion provided with a spline for torque transmission purposes on the inner wall and forming a geometric rotation axis. In fact, this spline ensures the function of transmitting torque to the wheel by enabling coupling with the transmission bowl-shaped body.

[0007] The axial cavity of the hub has an opening at the end where the inner ring retaining mechanism is located. This opening is configured to receive the splined shaft portion of the transmission cup when the transmission cup is assembled to the hub, and to cooperate with the internal splines of the hub's axial cavity.

[0008] The broaching process to obtain the spline can be performed on the hub alone prior to the assembly of the bearing. For example, the solution described in US 7,707,724 B2 (Patent Document 1) falls into this category. However, in this case, assembling the bearing after the spline has been formed causes the spline to shrink in diameter, which reduces its geometric accuracy, specifically its linearity. This occurs even if a constraint process for the shrink-fit region is performed during the broaching process.

[0009] One possible solution to the above problems is to perform broaching after the final assembly of the bearing. However, this method has significant limitations from a manufacturing perspective because it requires the use of broaching equipment at a stage within the manufacturing process, and generally speaking, it would result in many additional cost factors. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] U.S. Patent No. 7707724 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] The present invention aims to eliminate some or all of the shortcomings of the prior art. Specifically, it achieves this objective by proposing a manufacturing method for an assembly comprising a drive wheel hub and at least one bearing ring, which prevents deterioration of the linearity of the splines after spline formation, ensures perfect torque transmission between the transmission bowl-shaped body and the wheel hub, and ensures easy assembly of these two parts. [Means for solving the problem]

[0012] To accomplish this, a first aspect of the present invention proposes a method for assembling at least one raceway that cooperates in a shrink fit with a shrink fit surface of a part. The part forms a reference axis and has an axial cavity through it. The shrink fit surface faces radially opposite the reference axis. The part has an upper free end and an inner wall. The inner wall extends around the reference axis, faces radially opposite to the reference axis, and extends axially while forming at least a portion of the axial cavity, preferably extending axially so as to at least partially overlap the shrink fit surface in the axial direction. The assembly method comprises: forming an axially extending spline on the inner wall; and shrink fitting the raceway to the shrink fit surface of the part such that the lower lateral surface of the raceway abuts against the shoulder portion of the part. The assembly method includes: a step of elastoplastically expanding the upper portion of the part in the radial direction between the step of forming the spline and the step of shrink-fitting the raceway ring onto the shrink-fitting surface of the part, thereby widening a portion of the spline and the shrink-fitting surface; and a notable feature is that, after the step of machining the shrink-fitting surface as necessary, the upper portion deforms as the raceway ring is shrink-fitted onto the shrink-fitting surface, causing a portion of the spline to approach the reference axis.

[0013] "Elastic-plastic" expansion should be understood as expansion that first unfolds as elastic deformation and then progresses as plastic deformation. Therefore, after the radial elastoplastic expansion of the upper portion of the part is performed, the part does not return to its original shape, and the expanded diameter of both the portion of the spline and the shrink-fit surface is maintained.

[0014] This method allows the radial expansion step to be carried out independently of the spline formation step. This has the direct advantage of allowing the method to be carried out independently of other steps that may, in some cases, be performed on different equipment or in different locations.

[0015] Another advantage of this method is that, regardless of the axial holding configuration of the inner ring in the component, the need for diameter reduction prediction can be faithfully addressed by adjusting the required elastoplastic deformation based on the type of bearing. This deformation adjustment can be predetermined, in particular, by conducting multiple tests, and can take into account the influence of various subsequent processes that may affect the deformation of the upper portion.

[0016] In one embodiment, the portion of the spline includes, or is composed of, a portion that at least partially overlaps the shrink-fit surface in the axial direction.

[0017] In one embodiment, the component is a single object.

[0018] In one embodiment, the component is made of metal, preferably steel, and more preferably steel. Reasons for selecting such a material include its structural properties and its elastoplastic behavior.

[0019] In one embodiment, due to the radial elastoplastic expansion of the upper portion of the part, at least one cylindrical portion of the axial cavity deforms into a flared portion where the smaller diameter after expansion of the same cylindrical portion is greater than or equal to the nominal diameter before expansion. As a result, the radial expansion of the corresponding portion of the axial cavity progresses gradually along the reference axis. This flaring is oriented toward the upper free end in the axial direction of the upper portion, which is configured to receive the transmission portion.

[0020] In one embodiment, continuous control of the radial elastoplastic expansion of the upper portion of the part is performed during the process of the radial elastoplastic expansion. Preferably, the process of radially elastoplastic expansion of the upper portion of the part is controlled according to the data of the performed continuous control. This provides complete control of the elastoplastic expansion process.

[0021] In one embodiment, the axial position of the radial elastoplastic expansion of the upper portion of the part is between the shoulder portion and the upper free end of the bearing surface of the part.

[0022] In one embodiment, the axial cavity has at least one inner diameter variation portion that is oriented toward the upper free end in a direction that reduces the wall thickness of the cylindrical bearing surface, and the axial position of the at least one inner diameter variation portion is between the shoulder portion and the upper free end of the cylindrical bearing surface of the part.

[0023] In one embodiment, the step of radially elastic-plastic expansion includes using a radially expanding tool, particularly a radially expanding tool that converts axial displacement into radial expansion displacement. Preferably, it includes a step of inserting and arranging a plurality of expansion segments distributed around an expansion cone at the upper free end, and a step of applying an axial force to the expansion cone. Of course, other elastic-plastic expansion methods can also be used, such as directly applying an expansion tool (e.g., a cone, etc.) with a predetermined shape (axial force) to the area to be expanded in a flaring manner, a method of expanding the expansion tool by introducing a tool for fluid pressurization, and even any other method that can ensure the desired deformation.

[0024] In one embodiment, the step of forming an open spline on the inner wall is a broaching process.

[0025] In one embodiment, the inner wall is a rotating inner wall.

[0026] In one embodiment, the assembly method further includes, after the step of shrink-fitting the raceway ring, a step of forming an annular flange from the upper free end of the component, and a step of axially supporting and fixing the raceway ring to the shoulder portion of the bearing surface of the component by the pressing surface of the annular flange that abuts against the upper lateral surface of the raceway ring. Of course, as the installation mode of the raceway ring, other alternative or complementary installation modes are also possible. For example, it is also possible to provide a screwed transmission part to press against the raceway ring instead of the annular flange.

[0027] In one embodiment, the step of forming the annular flange portion locally deforms the upper portion such that, for example, a portion of the spline overlapping the shrink-fitting target surface approaches the reference axis. In such a configuration, the step of elastically and plastically deforming the upper portion of the component in the radial direction takes into account not only the subsequent step of shrink-fitting the race ring to the shrink-fitting target surface but also this step of deforming the upper portion. As a result, although the spline is deformed in various steps of the implemented assembly method, it becomes maximally straight after completion of the assembly method.

[0028] In one embodiment, the step of forming the annular flange portion consists of a caulking step, preferably a rocking caulking step. This rocking caulking step may also be referred to as "heading". In this case, the step of shrink-fitting the race ring to the shrink-fitting target surface of the component is configured such that the lower lateral surface of the race ring abuts against the shoulder portion of the component and the upper free end of the component protrudes axially from the upper lateral surface of the race ring. Thereby, it becomes possible to form the annular flange portion from the portion protruding from the upper free end of the component.

[0029] In one embodiment, the step of radially elastically and plastically expanding the upper portion of the component is configured such that both the portion of the spline overlapping the shrink-fitting target surface and the shrink-fitting target surface have a predetermined flare. This diameter expansion is predetermined such that the spline of the assembled product becomes maximally straight in accordance with subsequent steps that tend to locally deform the upper portion, such as the portion of the spline overlapping the shrink-fitting target surface, in a direction approaching the reference axis.

[0030] In one embodiment, the race ring is an inner ring of a bearing, and the component is a hub, preferably a drive wheel hub.

[0031] The present invention further relates to a component intended to be assembled in the manner described above, in particular to a drive wheel hub for an automobile, A reference axis is formed, through which an axial cavity passes, configured to receive at least one shrinkage fit raceway, and facing radially opposite the reference axis, and a shrinkage fit target surface is located, The upper free end and An inner wall extending around the aforementioned reference axis, facing the radially opposite side to the aforementioned reference axis, and extending axially while forming at least a portion of the axial cavity, A spline extending axially on the inner wall, In a component having, The upper portion expands radially in an elastoplastic manner, and a part of the spline and the shrink-fit target surface expand in diameter. This concerns a component that is notable for having [a certain characteristic].

[0032] The present invention further relates to an assembly product such as a kit, comprising the aforementioned parts, in particular an automobile drive wheel hub, and at least one raceway configured to cooperate in a shrink-fit with the shrink-fit target surface of the part, wherein, in the assembled state, the raceway is shrink-fitted with the shrink-fit target surface of the part such that the lower lateral surface of the raceway abuts against the shoulder portion of the part, and the upper portion of the raceway deforms due to the shrink-fit of the raceway with the shrink-fit target surface, causing the part of the spline to approach the reference axis.

[0033] Another aspect of the present invention relates to an assembly comprising a component and a raceway ring that is shrink-fitted to the shrink-fit surface of the component, characterized in that it is obtained directly by the method described above.

[0034] Other features and advantages of the present invention will become apparent upon consideration of the following disclosures with reference to the accompanying drawings. [Brief explanation of the drawing]

[0035] [Figure 1] This is a cross-sectional view of a drive wheel hub before the broaching process in one embodiment. [Figure 2] This is a cross-sectional view of the hub in Figure 1 during the broaching process. [Figure 3] This is a cross-sectional view of the hub in Figure 2 after the spline formation process. [Figure 4] Figure 3 is a cross-sectional view showing the hub with the bearing inner ring compressed and fitted inside. [Figure 5] This is a cross-sectional view of the hub in Figure 4 after the crimping process. [Figure 6A] Figure 5 is a cross-sectional view of the spline portion of the hub. [Figure 6B] This graph shows the curves illustrating the effects of broaching, shrink fit, and crimping on the dimensions of the spline portion of the hub when the radial elastoplastic expansion process is not performed in this assembly method. [Figure 7] Figure 3 is a cross-sectional view showing the hub with the extension tool installed. [Figure 8] Figure 7 is an isometric view. [Figure 9] This is a cross-sectional view of the hub shown in Figure 7 or Figure 8 during the radial expansion process of the hub. [Figure 10] This is a cross-sectional view of the expanded hub shown in Figure 9 after the process of expanding the hub radially. [Figure 11A] Figure 5 is a cross-sectional view of the spline portion of the hub. [Figure 11B] This graph shows the curves illustrating the effects of broaching, shrinkage fitting, and crimping on the dimensions of the spline portion of the hub when the radial elastoplastic expansion process is performed before the shrinkage fitting and crimping processes as part of this assembly method. [Modes for carrying out the invention]

[0036] For clarity, the same reference numerals refer to the same or similar components in all figures.

[0037] Figures 1 to 5 are longitudinal cross-sectional views of the components 100 that make up the hub of an automobile's drive wheel, showing various steps in the process of assembling the raceway ring 10, which is the inner ring 10 of the bearing, to the hub 100.

[0038] As with the other diagrams, the diagram above only shows the inner ring 10 of the bearing. Generally speaking, the assembly 1 of the inner ring 10 and the hub 100 belongs to a rotating device intended to be rotated and guided by a suspension member (not shown) around a geometric axis of rotation X using a bearing.

[0039] Such bearings generally consist of an outer ring having two outer racing surfaces, a first inner racing surface 131 formed directly on the main body of the hub 100, a second inner racing surface 132 formed on the inner ring 10 fitted to the cylindrical bearing surface 110 of the hub 100, and a double row of rolling elements (not shown), such as balls, interposed between the racing surfaces. The outer ring generally has a fixing flange provided with an interface portion for fixing to the suspension member. The interface portion has, for example, a hole through which a screw for fixing to the suspension member is inserted.

[0040] Component 100 forms a reference axis X and has an axial cavity 120 passing through it. The shrink-fit surface 110 of the raceway ring 10, which is cylindrical in this example, faces the radially opposite side of the reference axis X. The inner wall 102, which is on the radially opposite side of the shrink-fit surface 110, faces the radially opposite side of the reference axis X, extends around the reference axis X, and extends axially along the coaxial X such that it overlaps with the shrink-fit surface 110 in the axial direction at least partially.

[0041] The hub 100 is intended to be rotationally driven by a kinetic chain output member of the transmission unit. Specifically, the output member is composed of a transmission-sealed bowl-shaped body (not shown) which may be constant velocity or pseudo-constant velocity. The components constituting the bowl-shaped body are provided with a spline shaft portion. The spline shaft portion is intended to be inserted into a pair of axially shaped axial cavities 120 formed in the hub 100, and more specifically, into a spline 103 (see Figure 3) that extends axially along the inner wall 102 of the axial cavities 120.

[0042] As shown in Figure 2, a process is carried out to form an axial spline 103 on the inner wall 102. Specifically, the process in this example to form the open spline 103 on the rotating inner wall 102 is a broaching process. In this process, a spline broaching tool 240 is forcibly inserted into the axial cavity 120, contributing to the machining of the axial cavity 120 by broaching. The chips generated by the forced insertion of the broaching tool 240 into the cavity 120 are easily discharged from the wide opening at the lower end, which is on the axial side opposite the upper free end 101 that forms an opening in the cavity 120 that opens axially and allows access for the broaching tool 240. The terms "upper" and "lower" ends of part 101 refer to the orientation of the part in the preferred assembly method described herein, not the final orientation of the assembled product. Naturally, this assembly method can also be implemented in a different orientation without distorting the present invention, and the above-mentioned features of "lower side" and "upper side" were simply chosen to match the orientation shown in the figure so that the two ends can be distinguished from each other. Similarly, the concept of the so-called upper "free" end is named after the part before assembly, with full awareness that it must subsequently undergo machining processes such as the crimping process to form the flange mentioned above.

[0043] The broaching tool 240 consists of, for example, a steel pin equipped with a series of teeth having cross-sections corresponding to the desired external shape. The length of the broach is determined by the number of teeth, and the number of teeth is determined by the amount of material to be removed. Generally, the amount of metal thickness removed by each tooth varies from 0.01 to 0.03 mm depending on its shape and detailed cross-section.

[0044] Here, the hub 100 is configured such that the spline 103 has a portion 104 that at least partially overlaps the shrink-fit surface 110 in the axial direction (see Figure 3). In other words, after the spline 103 is formed, the hub 100 includes an axially extending portion 104 where the corresponding portion of the spline 103 and the corresponding portion of the shrink-fit surface 110 overlap radially.

[0045] Figure 4 shows the process of shrink-fitting the raceway ring 10 onto the shrink-fit target surface 110 of the part 100 such that the lower side surface 11 of the raceway ring 10 abuts against the shoulder portion 105 of the part 100. Here, after the shrink-fitting of the inner ring 10 of the bearing is performed, the upper free end 101 of the part 100 protrudes axially from the upper side surface 12 of the raceway ring 10, which is on the axial opposite side of the lower side surface 11 with respect to the raceway ring 10.

[0046] In Figure 5, it can be seen that after the inner ring 10 is fitted, more specifically after the inner ring 10 is compressed, the annular end 101 on the axial upper side of the hub 100 is bent radially outward, preferably further axially toward the inner ring 10. Figure 5 depicts the assembly 1 obtained by the process after the compression fitting of the raceway ring 10, that is, the process of forming the annular flange 107 from the upper free end 101 of the part 100. The annular flange 107 thus formed presses one axial end of the raceway ring 10 against the shoulder portion 105 of the bearing surface 110 of the part 100 and the other axial end of the raceway ring 10 against the flange 107 by a pressing surface 108 that is applied to the upper lateral surface 12 of the raceway ring 10, thereby fixing the raceway ring 10 in the axial direction.

[0047] The process of forming the annular flange portion 107 is carried out by locally heating the component as needed, followed by material deformation, preferably by material deformation using a crimping machine. The flange portion 107 is formed by this deformation. Specifically, this is a crimping process, and more specifically, oscillating crimping.

[0048] The process of shrink-fitting the raceway ring 10 onto the shrink-fit target surface 110 of the part 100, and the process of oscillating crimping to form the flange portion 107, both have the common effect of causing deformation of the upper portion 106, specifically, deformation of the upper portion 106 including the portion 104 of the spline 103 that overlaps with the shrink-fit target surface 110. These deformations are in the direction that brings the upper portion 106 closer to the reference axis X. In other words, the shrink-fitting process of the raceway ring 10 causes a reduction in the diameter of the upper portion 106. In the case of oscillating crimping, this reduction in diameter generally increases with that process. This result is specifically illustrated in Figure 6B. Figure 6B is a graph showing the dimensional effects of the broaching process C1, shrink fitting process C3, and rocking crimping process C4, which are performed sequentially on the spline portion 130 of the hub 100. The graph is presented in comparison with Figure 6A, which is a detailed cross-sectional view of the spline portion 130 of the hub 100. The horizontal axis of the graph represents the axial position data (mm) of the spline portion 103 of the hub 100, and the vertical axis represents the measured value of the diameter error (microns).

[0049] The resulting assembly 1 is configured to receive the spline shaft portion of the transmission sealing bowl-shaped body into the axial cavity 120. The cooperation between this spline shaft and the corresponding splined axial cavity prevents relative rotation between these two parts, thereby enabling torque transmission during vehicle use.

[0050] Furthermore, the hub 100 is configured to also participate in the axial locking of the bowl-shaped body. Specifically, the axial cavity 120 is sized to allow insertion of the main body portion of the bowl-shaped body, which is provided with a tip portion having a male or female thread. The tip portion with the male or female thread receives the main body portion of a screw or nut with a female or male thread. The head of the screw is pressed against a washer that is pressed against the annular surface 125 of the hub 100, thereby forming a circular crown portion that covers the axial cavity 120 at the lower end of the hub 100. On the axial opposite side of the axial cavity 120, the annular surface of the bowl-shaped body is pressed against a corresponding surface of the hub 100 formed by the flange portion 107.

[0051] In the present invention, between the step of forming the spline 103 and the step of shrink-fitting the raceway ring 10 onto the shrink-fit target surface 110 of the part 100, a step of radial elastoplastic expansion of the upper portion 106 of the part 100 is performed.

[0052] Through this process, the upper portion 106 of the hub 100, specifically a part 104 of the spline 103 and the shrink-fit target surface 110, specifically the portion 104 that overlaps with the shrink-fit target surface 110 and the shrink-fit target surface 110, can be enlarged in diameter.

[0053] The location where the radial expansion is greatest is the upper free end 101. In this example, the maximum radial expansion measured at the upper end 101 may reach or exceed 200 microns. The required amount of radial expansion is predetermined and is related to the deformation observed in the broaching and shrink-fitting processes.

[0054] Between the elastoplastic expansion step and the shrink-fit step, the shrink-fit target surface 110 is subjected to machining or adjustment. The subsequent shrink-fit of the raceway ring 10 onto the shrink-fit target surface 110 deforms the upper portion 106, thus contributing at least partially to bringing the portion 104 of the spline 103 that overlaps with the shrink-fit target surface 110 closer to the reference axis X. If no subsequent crimping step is provided, this shrink-fit step may be the only deformation step that brings it closer to the reference axis X. However, if a crimping step is further provided after the shrink-fit of the raceway ring 10, the radial elastoplastic expansion step is configured to also take into account the deformation that brings it closer to the reference axis X due to the formation of the flange portion 107.

[0055] Figures 7 and 8 are cross-sectional views of the hub 100 during the process of such radial elastoplastic expansion of the upper portion 106 of the part 100 using the expansion tool 200 (one of which is an isometric view). The expansion tool 200 is configured to convert axial displacement into radial displacement. Specifically, the expansion tool 200 consists of a support 230 of multiple expansion segments 220 distributed around an expansion cone 210 and inserted into the upper free end 101. The support 230 allows force to be applied to the expansion segments 220 when an axial force is applied to the expansion cone 210. The set of expansion segments 220 is configured to form an annular assembly of expansion segments 220 distributed around the expansion cone 210.

[0056] The upper portion 106 of part 100 includes a cylindrical inner contact surface held by the axial cavity 120. This cylindrical inner contact surface is coaxial with the reference axis X and oriented toward the reference axis X. The axial position of this radial inner contact surface is between the upper free end 101 and the upper end of the spline 103 of the spline portion. The axial transition from the upper end of the spline 103 of the spline portion to the inner contact surface is represented by at least one internal diameter change portion 121 that extends in a substantially annular shape, either continuously or with interruptions. The axial position of this internal diameter change portion 121 is between the shoulder portion 105 of the cylindrical bearing surface 110 of part 100 and the upper free end 101. The internal diameter change portion 121 is oriented toward the upper free end 101 in a direction that reduces the wall thickness of the hub 100.

[0057] The support 230 is inserted into the axial cavity of the hub by the lower portion of the hub 100, which is on the axial side opposite the upper portion 106. In the expanded position, the large-diameter base of the support 230 is sized to abut axially against the annular surface 125 of the hub 100. The support 230 further comprises a shaft that is inserted into the axial cavity 120. The upper portion of this shaft includes a contact interface portion which can serve as the endpoint contact point for axial movement during the expansion process for the expansion segments 220 distributed around the expansion cone 210.

[0058] The support 230 has an axially oriented recess at its tip on the side facing the expansion cone 210. This axial recess ensures the axial movement of the expansion cone 210.

[0059] To carry out the process of radial elastoplastic expansion of the upper portion 106 of the part 100, the support 230 is inserted into the axial cavity at the lower portion of the vertically positioned hub 100, until it contacts the hub 100 in the axial direction. Specifically, the wide base of the support is supported by an annular surface 125 of the hub 100, which has a radial dimension larger than the axial cavity portion 120.

[0060] As a result, the extension segments 220 are inserted through the upper free end 101 and positioned within the upper portion 106. Each extension segment 220 is positioned so as to be radially supported in contact with a portion of the cylindrical radial contact surface held by the axial cavity 120 of the upper portion 106, and axially supported on the support surface at the tip of the support 230. The positioned extension segments 220 form an annular assembly 220'. In the annular assembly 220', each segment 220 corresponds to a portion of the annular assembly that extends in a sector shape at a predetermined angle. This annular assembly 220' has a radial outer surface 221' formed by the circumferential continuity of the individual outer surfaces of the segments 220, and a radial inner surface 222' that forms a space for housing the extension cone 210. This inner surface is formed by the fact that the individual inner surfaces of the segments 220 along the sector of the corresponding angle continue almost continuously in the circumferential direction, and extends to form a frustoconical rotating surface around the reference axis X, with the diameter decreasing toward the center of the axial cavity 120.

[0061] Specifically, in this method, at least during the radial expansion step, it is preferable that the upper portion 106 of the part 100 is raised vertically upward so that the reference axis X is vertically aligned and the hub 100 is directed accordingly. With this configuration, the tools used are limited, and stability, specifically the stability of the part 100 and the support 230, is ensured by cleverly utilizing gravity, making the implementation of this method easy and simple.

[0062] As shown in Figures 7 and 8, at least one spring 223 is arranged in an annular manner to radially surround all segments 220. For this purpose, at least one circular groove 224 may be provided to surround the radial outer surface 221' held by the assembly of segments 220. Such a spring 223 is intended to hold the assembly of segments 220 together by constraining them radially inward, i.e., toward the reference axis X. This facilitates the operation of the segments 220, in particular, when inserted through the upper free end 101 and positioned in the upper portion 106 of the axial cavity 120.

[0063] An axial force is applied to the inner surface 222' using an extended cone 210, which actually has an outer shape that is approximately frustoconical and complementary to the shape formed by the radial inner surface 222' of the annular assembly 220'. As these two frustoconical surfaces slide against each other, a force having both an axial and radial component is generated on the annular assembly 220'.

[0064] Furthermore, the installation of the expansion cone 220 and the segment 220 can be carried out simultaneously. This is especially true when the annular assembly 220' is held in radial contact with the expansion cone 210 by the annular spring surrounding the annular assembly 220', and one axial end of the annular assembly 220' is held to the expansion cone 210 by its conical shape, while the other axial end of the annular assembly 220' is held by a flange protruding annularly from the small-diameter base of the expansion cone 210.

[0065] The axial component of the force is absorbed by the support 230 through a flat bearing surface that is contained in a plane perpendicular to the reference axis X and forms the tip of the support 230. In light of the structure of the extension tool 200 and the support 230, the flat bearing surface that forms the tip of the support 230 is positioned in the axial direction approximately on the upper free end 101 side of the spline 103 of the spline portion, and more generally on the upper free end 101 side of the diameter change portion 121, in order to prevent the segment 220 from contacting the spline 103 of the spline portion or from interacting with the spline 103. As a result, the axial resultant force of the force is absorbed by the support 230.

[0066] The axially open recess, which opens onto this flat support surface and is aligned with both the tip of the support 230 and the reference axis X, allows the expansion cone 210 to secure a sufficient and necessary stroke without interfering with the flat support surface on which the segment 220 is mounted.

[0067] The radial component of the force is absorbed by the upper portion 106 held by the axial cavity 120. As a result, the portion 104 of the spline 103 that overlaps with the shrink-fit surface 110, and the shrink-fit surface 110 itself, are expanded in diameter by a predetermined sufficient force. This flaring is shown in Figures 9 and 10 by the corresponding dotted line of the upper portion 106. The axial position of the entire flaring is between the upper free end 101 and the shoulder portion 105 of the shrink-fit surface 110 of the part 100.

[0068] Due to the radial elastoplastic expansion of the upper portion 106 of part 100, at least one cylindrical portion of the axial cavity 120 deforms into a flared portion where the smaller diameter Ds of the expanded cylindrical portion is greater than or equal to the nominal diameter Dn before expansion.

[0069] The radial expansion is elastoplastic, meaning it initially unfolds as elastic deformation and then progresses as plastic deformation. While it elastically recovers as appropriate once the expansion force is removed, it does not return to its original state before expansion. To prevent damage to the hub, this plastic deformation must be completely controlled. As shown in Figure 9, deformation control is ensured by continuous control of the radial expansion process of the upper portion 106 of part 100. Preferably, the expansion process is controlled according to the data from the continuous control performed. Preferably, this control is also continuous.

[0070] Figure 11B is a graph of curves representing the effects of the broaching process C1', expansion process C2', shrink fitting process C3', and oscillating crimping process C4' on the dimensions of the spline portion 103 of the hub 100. The curves are shown in comparison with Figure 11A, which is a detailed cross-sectional view of the spline portion 103 of the hub 100.

[0071] After the broaching process, the expansion process is performed, which tends to enlarge the upper portion 106. The subsequent shrink-fitting and crimping processes tend to deform the upper portion 106, particularly the shrink-fitting target surface 110, in a direction that moves it closer to the reference axis X. This not only ensures proper mounting of the raceway ring 10 to the shrink-fitting target surface 110, but also ensures that the linearity of the spline 103 is very close to that of the original spline immediately after the broaching process. In particular, if the shrink-fitting diameter exceeds the inner diameter of the raceway ring due to the expansion, a machining process may be performed between the expansion process and the shrink-fitting process to enable the assembly of the raceway ring.

[0072] Specifically, the graph shows the change in the linearity of the spline during the processes performed, where curve C1 represents the linearity of the spline 103 obtained in the broaching process, curve C2' represents the linearity of the spline 103 after the subsequent elastoplastic expansion process, curve C3' represents the linearity of the spline 103 after the subsequent shrink-fitting process of the inner ring 10, and the final curve C4' represents the final linearity of the spline 103 after the crimping process.

[0073] This demonstrates that linearity close to the original value (defect: less than 20 μm) can be obtained, thus proving the efficiency of this method. In fact, this assembly method is configured such that the diameter error of the axial cavity 120 measured by the spline 103 between the step before the radial elastoplastic expansion of the upper portion 106 and the step after the assembly method of the raceway ring 10 is 20 μm at the point when the assembled product 1 can be connected to the transmission bowl-shaped body (for example, after shrink fitting of the raceway ring 10 and any crimping). Such measurements are performed, for example, using a ball feeler method.

[0074] At the time the inner ring 10 is shrink-fitted onto the hub 100, the assembly components are in their pre-assembly state. In this pre-assembly state of the raceway ring 10 onto component 100, the upper portion 106 of component 100 is elastoplastically expanded in the radial direction, and the portion of the spline 103 that overlaps with the shrink-fitting target surface 110 and the shrink-fitting target surface 110 are enlarged in diameter.

[0075] In the assembled state according to the embodiment described herein, the raceway ring 10 is shrink-fitted to the shrink-fit target surface 110 of the part 100 such that the lower side surface 11 of the raceway ring abuts against the shoulder portion 105 of the part 100, and the upper free end portion 101 of the part protrudes axially from the upper side surface 12 of the raceway ring 10. Preferably, depending on the subsequent process, the shrink-fit target surface 110 is at least partially machined. At least the upper portion 106 of the raceway ring 10 is elastically deformed by shrink-fitting the raceway ring 10 to the shrink-fit target surface 110, and at least the portion 104 of the spline 103 that overlaps with the shrink-fit target surface 110 approaches the reference axis X.

[0076] It can be seen that the elastoplastic expansion process and the shrinkage fit process can be easily carried out in separate geographical locations. In other words, such an elastoplastic expansion process is easy to implement and does not require the use of spline forming means in the same production location.

[0077] Naturally, the description of the present invention to date is merely illustrative. Those skilled in the art will likely be able to create various modifications of the present invention without departing from its scope.

[0078] For example, the shrink-fitting process may consist of shrink-fitting a plurality of raceway rings 10, for example, two raceway rings 10, onto the shrink-fitting target surface 110 of the part 100. In this case, the raceway rings 10 are arranged in a line coaxially with the reference axis X. Of these raceway rings 10, for example, the first raceway ring, it can be seen that its lower side surface 11 abuts against the shoulder portion 105 of the part 100. The lower side surface 11 of the second raceway ring may or may not abut against the upper surface of the first raceway ring 10.

[0079] All configurations that will be obvious to those skilled in the art from this specification, drawings, and appended claims are described only in relation to other predetermined configurations. However, it should be emphasized that such configurations alone or in appropriate combinations thereof may be combined with other configurations or sets of configurations of this disclosure, unless such combinations are expressly excluded or are impossible or meaningless under technical conditions.

Claims

1. A method for assembling at least one bearing ring (10) that cooperates in a shrink fit with a shrink fit mating surface (110) of a part (100), comprising the steps of: The part (100) defines a reference axis (X) and has an axial cavity (120) therethrough, The shrink-fitted mating surface (110) faces radially opposite the reference axis (X), The part (100) has an upper free end (101) and an inner wall (102), The inner wall (102) extends around the reference axis (X), faces a radially opposite side of the reference axis (X), and extends in an axial direction while forming at least a portion of the axial cavity (120), The assembly method comprises: forming axially extending splines (103) on the inner wall (102); shrink-fitting the race (10) onto the shrink-fit mating surface (110) of the part (100) so that the lower lateral surface (11) of the race (10) abuts against the shoulder portion (105) of the part (100); The assembling method further comprises: a step of elastically and plastically expanding an upper portion (106) of the part (100) in the radial direction after the step of forming the spline (103) and before the step of shrink-fitting the race (10) onto the shrink-fit surface (110) of the part (100), thereby enlarging a portion (104) of the spline (103) and the shrink-fit surface (110); and after this step, the race (10) is shrink-fitted onto the shrink-fit target surface (110), thereby deforming the upper portion (106) and bringing the portion (104) of the spline (103) closer to the reference axis (X).

2. 2. The assembly method according to claim 1, wherein the portion (104) of the spline (103) includes a portion that at least partially overlaps the shrink-fit mating surface (110) in the axial direction.

3. 3. The assembly method according to claim 1, wherein the radial elastic-plastic expansion of the upper portion of the part causes at least one cylindrical portion of the axial cavity to deform into a flared portion, the smaller diameter of the cylindrical portion after expansion being equal to or greater than the nominal diameter before expansion.

4. 3. The assembly method according to claim 1 or 2, characterized in that in the step of radial elastic-plastic expansion of the upper portion (106) of the part (100), continuous control of said expansion is performed.

5. 3. The assembly method according to claim 1 or 2, characterized in that the axial position of the radial elastic-plastic expansion of the upper portion (106) of the part (100) is between the shoulder portion (105) and the upper free end portion (101) of the shrink-fit mating surface (110) of the part (100).

6. 3. The assembly method according to claim 1 or 2, characterized in that the axial cavity (120) has at least one inner diameter change (121) oriented in a direction of reducing the thickness of the cylindrical bearing surface (110) towards the upper free end (101), and the axial position of the at least one inner diameter change (121) is between the shoulder (105) and the upper free end (101) of the cylindrical bearing surface (110) of the part (100).

7. 3. The assembly method according to claim 1 or 2, characterized in that the step of radial elastic-plastic expansion comprises using a radial expansion tool (200).

8. 3. A method according to claim 1 or 2, characterized in that the step of forming open splines (103) in the inner wall (102) is a broaching step.

9. The assembly method according to claim 1 or 2, further comprising: after the step of shrink-fitting the race (10), forming an annular collar (107) from the upper free end (101) of the part (100), wherein the race (10) is axially supported and fixed to the shoulder (105) of the bearing surface (110) of the part (100) by a pressing surface (108) of the annular collar (107) that rests against the upper lateral surface (12) of the race (10); An assembly method comprising:

10. 9. The assembly method according to claim 8, wherein the step of forming the annular flange portion (107) includes locally deforming the upper portion (106) of the spline (103) so that a portion of the spline (103) that overlaps with the shrink-fit target surface (110) approaches the reference axis (X).

11. 10. The assembly method according to claim 8 or 9, wherein the step of forming the annular flange (107) comprises a crimping step.

12. 3. The assembly method according to claim 1 or 2, characterized in that the race (10) is an inner race of a bearing and the part (100) is a hub.

13. A component (100) intended to be assembled with at least one bearing ring (10) by the assembly method according to claim 1 or 2, a shrink-fit mating surface (110) defining a reference axis (X) and having an axial cavity (120) therethrough, the shrink-fit mating surface (110) being configured to receive at least one shrink-fit race (10) and facing radially opposite the reference axis (X); an upper free end (101); an inner wall (102) extending around the reference axis (X), facing a radially opposite side of the reference axis (X), and extending axially while forming at least a portion of the axial cavity (120); a spline (103) extending axially on the inner wall (102); The component (100) further comprises: an upper portion (106) that expands radially elastically and plastically, and in which a portion of the spline (103) and the shrink-fit mating surface (110) expand in diameter; Component (100), characterized in that it has:

14. A component (100) according to claim 13; at least one race (10) configured to cooperate in a shrink fit with a shrink fit mating surface (110) of said component (100); In an assembly product (1), In an assembled state, the raceway (10) is shrink-fitted onto the shrink-fit surface (110) of the part (100) so that a lower lateral surface (11) of the raceway abuts against a shoulder portion (105) of the part (100), and the shrink-fitting of the raceway (10) onto the shrink-fit surface (110) causes the upper portion (106) to deform, so that the portion (104) of the spline (103) approaches the reference axis (X).

15. 1. An assembly (1) of a part (100) and a bearing ring (10) shrink-fitted onto a shrink-fit mating surface (110) of the part (100), characterized in that the assembly (1) is obtained directly by the method according to claim 1 or 2.

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