CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to co-pending U.S. Provisional Patent Application

No. 61/781,699 filed on March 14, 2013, the entire content of which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to wheel assemblies, and more particularly to vehicle wheel assemblies.

BACKGROUND OF THE INVENTION

[0003] Most wheeled vehicles include hubs that are rotatably supported by spindles. In the case of a semi-trailer, spindles may be used on the steering axles, the drive axles, or the trailer axles of the semi-trailer. Wheels are usually secured to the respective hubs by axle lugs and corresponding nuts.

SUMMARY OF THE INVENTION

[0004] The wheel assembly provides, in one aspect, a rim, a hub unitized with the rim for co-rotation therewith without using fasteners, and a braking member fastened to one of the rim and the hub for co-rotation therewith.

[0005] In another aspect, a method for manufacturing a wheel assembly includes using a rotary inertial welding process. The method includes providing a rim and a hub portion separate from the rim, holding one of the rim and the hub portion stationary, rotating the other of the rim and the hub portion, joining the hub portion to the rim while the one of the rim and the hub portion is rotating to generate a frictional force between the rim and the hub portion, and fusing the hub portion to the rim with heat generated by the frictional force.

[0006] The wheel assembly may also be manufactured using a friction stir welding process. Such a process includes providing a rim and a hub portion separate from the rim, positioning the hub portion adjacent the rim and holding the hub portion stationary relative to the rim, contacting the rim and the hub portion with a rotating tool bit to generate a frictional force between the rim and the hub portion, moving one of the rotating tool bit and the rim relative to the other of the tool bit and the rim along a path while the rotating tool bit is contacting the rim and the hub portion, and fusing the hub portion to the rim with heat generated by the frictional force as the tool bit circumscribes the path.

[0007] The wheel assembly may alternatively be manufactured using a forging process.

Such a process includes providing a metal billet, impacting the billet with a first strike to form a rim portion and a hub portion, impacting the rim portion and the hub portion of the billet with a second strike, thereby widening the rim portion and creating a blind bore in the hub portion. The method also includes impacting the rim portion and the hub portion with a third strike, further widening the rim portion and lengthening the blind bore in the hub portion. The method further includes impacting the hub portion with a fourth strike to remove excess material from the hub portion, thereby making the blind bore into a through bore.

[0008] Other features and aspects of the invention will become apparent by consideration of the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a cross-sectional view of a wheel assembly in accordance with an embodiment of the invention.

[0010] FIG. 2 is a cross-sectional view of a unitized rim and hub of the wheel assembly of FIG. 1.

[0011] FIG. 3 is a cross-sectional view of a braking member of the wheel assembly of

FIG. 1

[0012] FIG. 4 is a perspective view of a pilot ring of the wheel assembly of FIG. 1.

[0013] FIG. 5 is a cross-sectional view of a rim and a hub portion prior to being unitized to create the unitized rim and hub of FIG. 2. [0014] FIG. 6 is a cross-sectional view of the rim and hub portion of FIG. 5 after being unitized by a rotary inertial welding process.

[0015] FIG. 7 is a cross-sectional view of a rim prior to being unitized with a hub portion to create the unitized rim and hub of FIG. 2.

[0016] FIG. 8 is a cross-sectional view of a hub prior to being unitized with a rim to create the unitized rim and hub of FIG. 2.

[0017] FIG. 9 is a cross-sectional view of the rim and hub portion of FIGS. 7 and 8 after being unitized by a friction stir welding process.

[0018] FIG. 10 is a perspective view of a portion of the rim and hub portion of FIGS. 7 and 8, illustrating a path circumscribed by a rotating tool bit during the friction stir welding process.

[0019] FIG. 11 is a plan view of a billet for use in a closed-die, multiple-strike forging process to create the unitized rim and hub of FIG. 2.

[0020] FIG. 12 is a cross-sectional view of the billet of FIG. 11 after a first strike of the forging process, thereby creating a rim portion and a hub portion.

[0021] FIG. 13 is a cross-sectional view of the rim and hub portions of FIG. 12 after a second strike of the forging process.

[0022] FIG. 14 is a cross-sectional view of the rim and hub portions of FIG. 13 after a third strike of the forging process.

[0023] FIG. 15 is a cross-sectional view of the rim and hub portions of FIG. 14 after a fourth strike of the forging process.

[0024] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

DETAILED DESCRIPTION

[0025] FIG. 1 illustrates a wheel assembly 10 including a unitized or integrated wheel/hub 14 (see also FIG. 2). The wheel/hub 14 includes a rim portion or rim 18 to which a tire is mounted (not shown) and a hub portion or hub 22 unitized or integrally formed with the rim 18 for co-rotation therewith. The hub 22 includes coaxial bores 26 in which respective bearings 30 (FIG. 1) are supported. In the illustrated embodiment of the wheel assembly 10, the bearings 30 are configured as tapered roller bearings 30 for handling both radial and thrust loads. Alternatively, the bearings 30 may have any of a number of different configurations (e.g., cartridge or standard bearing configurations), and the hub 22 may be machined in an appropriate manner for receiving such bearing configurations. The wheel assembly 10 is directly mounted and axially retained to a vehicle spindle by inserting the spindle through the bearings 30 in the hub 22.

[0026] With reference to FIGS. 1 and 3, the wheel assembly 10 also includes a braking member 34 fastened to the hub 22 (e.g., using bolts 38 and nuts 42) for co-rotation therewith. In the illustrated embodiment of the wheel assembly 10, the braking member 34 is configured as a drum 46 for use with a drum-braking system. To reduce the overall weight of the wheel assembly 10, the drum 46 may be made of a lightweight gray iron alloy, such as that described in U.S. Patent No. 7,163,594, the entire content of which is incorporated herein by reference.

Particularly, the gray iron alloy may include, as a percentage of weight: about 4.10% to about 4.25% carbon equivalent, about 3.5% to about 3.65% carbon, about 0.4% to about 0.9% manganese, about 1.5% to about 1.9% silicon, less than about 0.12% phosphorous, less than about 0.17%) sulfur, about 0.6%> to about 0.8%> molybdenum, and about 0.3%> to about 0.6%> copper with the balance being essentially iron. Alternatively, the drum 46 may be made of any number of different metals, metal alloys, or high-strength non-metals. As a further alternative, the braking member 34 may be a disc for use with a disc-braking system.

[0027] With reference to FIGS. 1 and 4, the wheel assembly 10 further includes a pilot ring 50 positioned between the hub 22 and the drum 46. The pilot ring 50 inhibits wear and fretting on the hub 22 while also providing a thermal barrier. Such a pilot ring 50 is described in more detail in U.S. Patent No. 7,159,697, the entire content of which is incorporated herein by reference. Alternatively, the pilot ring 50 may be omitted from the wheel assembly 10.

[0028] With reference to FIGS. 5 and 6, the unitized wheel/hub 14 can be made using a rotary inertial welding process. In such a process, the rim 18 may be forged from a metal billet to include a portion of the hub 22, or a first hub portion 54 (FIG. 5), while a second hub portion 58 is forged from a separate metal billet. Alternatively, the second hub portion 58 may be machined from a cast billet. Prior to initiating the rotary inertial welding process, mating surfaces 62, 66 of the first and second hub portions 54, 58, respectively, are machined to ensure flatness and improve the resultant bond between the first and second hub portions 54, 58.

[0029] To initiate the rotary inertial welding process, the rim 18 and first hub portion 54 are held stationary while the second hub portion 58 is rotated. Alternatively, the rim 18 and first hub portion 54 may be rotated while the second hub portion 58 remains stationary. Then, the second hub portion 58 is joined to the first hub portion 54 while the second hub portion 58 is rotating to generate a frictional force between the first and second hub portions 54, 58. The first and second hub portions 54, 58 are fused together with heat generated by the frictional force (FIG. 6). The unitized or fused first and second hub portions 54, 58, with the rim 18, are thereby made integral and into a single piece. The unitized wheel/hub 14 may then be spun using a rim spinning machine until it reaches a near-final shape, heat treated to obtain a desired hardness, and machined in accordance with the intended application of the wheel/hub 14 to a final shape.

[0030] With reference to FIGS. 7-9, the unitized wheel/hub 14 can also be made using a friction stir welding process. In such a process, the rim 18 may be forged from a metal billet (FIG. 7), while the hub 22 is forged from a separate metal billet (FIG. 8). Alternatively, the hub 22 may be machined from a cast billet. Prior to initiating the friction stir welding process, mating surfaces 70, 74 of the rim 18 and the hub 22 (FIGS. 7 and 8), respectively, are machined to ensure flatness and improve the resultant bond between the rim 18 and the hub 22.

[0031] To initiate the friction stir welding process, the hub 22 is positioned adjacent the rim 18 and held stationary relative to the rim 18. In other words, the hub 22 is maintained stationary adjacent the rim 18 such that mating surfaces 70, 74 of the rim 18 and the hub 22, respectively, are in facing relationship. A nominal clearance may exist between the mating surfaces 70, 74 such that the surfaces 70, 74 contact via a loose sliding fit. The rim 18 and the hub 22 are then contacted by a rotating tool bit at a location coinciding with an interface 78 (FIGS. 9 and 10) between the mating surfaces 70, 74 to generate a frictional force between the rim 18 and the hub 22 within the plane of contact between the tool bit, the rim 18, and the hub 22. Then, the rim 18 and the hub 22 are rotated together relative to the tool bit (FIG. 10), causing the tool bit to circumscribe a path (indicated by arrow 82) along the interface 78 as the tool bit frictionally engages the rim 18 and the hub 22. Alternatively, the rim 18 and the hub 22 may be held stationary, and the tool bit moved along a path coinciding with the interface 78. The rim 18 and the hub 22 are fused together with heat generated by the frictional force as the tool bit circumscribes the path 82. The unitized or fused rim 18 and hub 22 are thereby made integral and into a single piece. The unitized wheel/hub 14 may then be spun using a rim spinning machine until it reaches a near-final shape, heat treated to obtain a desired hardness, and machined in accordance with the intended application of the wheel/hub 14 to a final shape.

[0032] Alternatively, with reference to FIGS. 11-15, the unitized wheel/hub 14 can be made using a closed-die forging process using multiple impacts. A metal billet 86 is initially provided (FIG. 11), which is impacted with a first strike of the forging process to form a rim portion 18 and a hub portion 22 (FIG. 12). The rim portion 18 and the hub portion 22 are then impacted with a second strike, thereby widening the rim portion 18 and creating a blind bore 90 in the hub portion 22 (FIG. 13). A third strike of the forging process further widens the rim portion 18 and lengthens the blind bore 90 in the hub portion 22 (FIG. 14). The hub portion 22 is then impacted with a fourth strike to remove excess material from the hub portion 22, thereby making the blind bore 90 into a through bore 94 (FIG. 15) which is subsequently machined to receive bearings 30 (FIG. 1). The rim portion 18 and hub portion 22 are therefore integrally formed as a single piece from a single metal billet. The unitized wheel/hub 14 may then be spun using a rim spinning machine until it reaches a near-final shape, heat treated to obtain a desired hardness, and machined in accordance with the intended application of the wheel/hub 14 to a final shape.

[0033] Various features of the invention are set forth in the following claims.