Wheel Disc for a Disc Wheel

Abstract

A wheel disc for a disc wheel, especially for utility vehicles; with an essentially radially extending hub fitting flange and an essentially cylindrical disc edge which can be joined to a wheel rim, and with a transition region extending between the hub fitting flange and the disc edge, wherein the transition region is subdivided into at least five segments (Ai to v) passing into each other or into the hub fitting flange or the disc edge, each of which has an outer end situated closer to the hub fitting flange and an inner end situated closer to the disc edge, wherein neighbouring segments have curvatures with different directions and variable material thickness, with the ratios of the material thicknesses and the ratio of their lengths to heights are chosen as follows:

TABLE-US-00001 Material thickness of Length in axial inner end direction Material thickness of Height in radial outer end direction Segment A.sub.I 0.45-0.7  0.9-1.1 (between hub fitting flange and segment A.sub.II) Segment A.sub.II 0.7-1.0  1.6-1.9 (between A.sub.I and A.sub.III) Segment A.sub.III 0.9-1.25 2.5-2.8 (between A.sub.II and A.sub.IV) Segment A.sub.IV 0.9-1.25 2.8-3.1 (between A.sub.III and A.sub.V) Segment A.sub.V 0.7-1.15 6.0-6.8 (between A.sub.IV and disc edge)

Claims

1. A wheel disc for a wheel with an essentially radially extending hub fitting flange and an essentially cylindrical disc edge being joinable to a wheel rim, and with a transition region extending between the hub fitting flange and the disc edge, wherein the transition region is subdivided into at least five segments (A.sub.I to V) passing into each other or into the hub fitting flange or the disc edge, each of which has an outer end situated closer to the hub fitting flange and an inner end situated closer to the disc edge, wherein the segments have a curvature at least on a partial region of their length between their outer end and their inner end and the curvatures of neighbouring segments have different directions of curvature, wherein the individual segments have at their inner ends a larger radial distance from an axis of rotation of the wheel disc than at their outer ends and wherein the wheel disc in its transition region has a variable material thickness, and wherein the ratios of the material thicknesses of the individual segments at their respective inner ends to their respective outer ends and the ratio of their lengths in the axial direction of the wheel disc to their heights in the radial direction are chosen as follows: TABLE-US-00006 Material thickness of inner end Material thickness of Length in axial direction outer end Height in radial direction Segment A.sub.I 0.45-0.7  0.9-1.1 (between hub fitting flange and segment A.sub.II) Segment A.sub.II 0.7-1.0  1.6-1.9 (between A.sub.I and A.sub.III) Segment A.sub.III 0.9-1.25 2.5-2.8 (between A.sub.II and A.sub.IV) Segment A.sub.IV 0.9-1.25 2.8-3.1 (between A.sub.III and A.sub.V) Segment A.sub.V 0.7-1.15 6.0-6.8 (between A.sub.IV and disc edge)

2. The wheel disc according to claim 1, wherein the second segment (A.sub.II) and/or the third segment (A.sub.III) has a subsegment (UA) without curvature extending over a partial region of the segment length.

3. The wheel disc according to claim 2, wherein the subsegment (UA) has a material thickness ratio of 0.9 to 1.25 and a length to height ratio of 1.4 to 1.7.

4. The wheel disc according to claim 1, wherein the material thickness of the first segment (A.sub.I) passing into the hub fitting flange at its outer end corresponds to the material thickness of the wheel disc in the region of the hub fitting flange.

5. The wheel disc according to claim 1, wherein the material thickness of the fifth segment (A.sub.V) passing into the disc edge at its inner end corresponds to the material thickness of the wheel disc in the region of the disc edge.

6. The wheel disc according to claim 1, produced on a flow forming machine by flow forming of a metallic blank, especially a steel blank, during elongation of a preformed marginal region adjoining the clamped hub fitting flange.

7. The wheel disc according to claim 1, wherein the fourth segment between its inner end and its outer end has a material thickening whose thickness is 1.1 to 1.3 times the material thickness at the outer end of the fourth segment.

8. The wheel disc according to claim 1, in which the hub fitting flange after making ready a wheel disc blank by flow forming of a metallic, especially a steel blank, is machined in a cutting process, especially on a lathe, and in which the transition region has an overall axial length, measured from the inside of the hub fitting flange to the inner end of the fifth segment bordering on the disc edge, wherein the segments of the transition region extend: Segment A.sub.I from the inside of the hub fitting flange to 9% to 12% of the overall axial length Segment A.sub.II from the inner end of segment A.sub.I to 43%-46% of the overall axial length Segment A.sub.III from the inner end of segment A.sub.II to 70%-75% of the overall axial length Segment A.sub.V from the inner end of A.sub.IV to 93%-97% of the overall axial length Segment A.sub.V from the inner end of A.sub.IV to the start of the disc edge.

9. The wheel disc according to claim 8, wherein the material thickness of the transition region at the transition points (MP) between the segments, in relation to the material thickness (MP.sub.0) of the machined hub fitting flange is TABLE-US-00007 Transition A.sub.I/A.sub.II = MP.sub.I : 50-55% .Math. MP.sub.0 Transition A.sub.II/A.sub.III = MP.sub.II : 45-52% .Math. MP.sub.0 Transition A.sub.III/A.sub.IV = MP.sub.III : 45-53% .Math. MP.sub.0 Transition A.sub.IV/A.sub.V = MP.sub.IV : 49-54% .Math. MP.sub.0 Transition A.sub.V/disc edge = MP.sub.V : 40-50% .Math. MP.sub.0

10. The wheel disc according to claim 9, wherein the material thickness of the second segment between its ends or transition points (MP.sub.I, MP.sub.II) is reduced to a value of 45% to 50% of the material thickness MP.sub.0 of the hub fitting flange.

11. The wheel disc according to claim 9, wherein the material thickening in the fourth segment is 55 to 65% of the material thickness (MP.sub.0) of the hub fitting flange.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is an upper half of a wheel disc according to the invention in radial cross section; and

[0032] FIG. 2 is the object of FIG. 1 in the transition region between hub fitting flange and disc edge illustrating the geometrical relations relevant to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0033] In the drawing, 10 denotes a wheel disc for a steel disc wheel of a utility vehicle. In its basic layout, the wheel disc follows known designs. It has an essentially radially extending hub fitting flange 11 and an essentially cylindrical, actually slightly conical toward the axis 12 of the wheel disc, disc edge 13 (aperture angle around 1.5°), with which the wheel disc can be joined in familiar fashion to a fitting region of a wheel rim (not shown).

[0034] Between the disc edge 13 and the hub fitting flange 11 there extends a transition region 14, which according to the invention is subdivided into at least five segments A.sub.I to A.sub.V passing into each other or into the hub fitting flange and the disc edge. In FIG. 1, the segment A.sub.I lies between the points MP.sub.0 and MP.sub.1, segment A.sub.II between the points MP.sub.1 and MP.sub.2, segment A.sub.III between the points MP.sub.2 and MP.sub.3, the fourth segment A.sub.IV between the points MP.sub.3 and MP.sub.4 and the last, fifth segment A.sub.V between the measurement points MP.sub.4 and MP.sub.5. Each of the segments A.sub.I to A.sub.V has an outer end situated closer to the hub fitting flange 11 and an inner end situated closer to the disc edge, which are located at the measurement points MP shown in the drawings. Each of the segments has a curvature at least on a partial region of its length between the respective outer and inner end, which are designated by the radii R.sub.I to R.sub.V shown in FIG. 1. The arrangement is such that the curvatures of neighbouring segments have different directions of curvature. Thus, while segment A has a convex curvature R.sub.I between the measurement points MP.sub.0 and MP.sub.I—as seen from the inside of the disc 18—the direction of curvature changes with the start of the second segment at measurement point MP.sub.I to a concave curvature R.sub.II with larger radius of curvature. After a subsegment UA of the second segment adjacent to the part with the radius of curvature R.sub.II, which subsegment is straight, i.e., with no curvature, there follows the third segment at measurement point MP.sub.II, which again has a convex curvature. At measurement point MP.sub.III once again there is a reversal of the direction of curvature to a concave curvature in segment A.sub.IV, and finally segment A.sub.V has a convex curvature between the measurement point MP.sub.IV and the measurement point MP.sub.V.

[0035] All segments A.sub.I-V have at their respective inner ends a larger radial distance from the axis of rotation 12 of the wheel disc 10 than at their outer ends situated closer to the hub fitting flange 11. The material thickness of the wheel disc in the transition region is variable, while the ratios of the material thicknesses of the individual segments A.sub.I to A.sub.V at their inner ends di to their respective outer ends da and the ratios of their lengths L.sub.a in the axial direction of the wheel disc to their heights H.sub.r in the radial direction in the preferred sample embodiment shown for a wheel disc of a vehicle wheel with 22.5 inch rim diameter are chosen as follows:

TABLE-US-00005 Ratio of material Ratio of length in axial thickness of inner end direction to height in to outer end (di/da) radial direction L.sub.a/H.sub.r Segment I 0.54 1.04 Segment II 0.92 1.74 Segment III 1.02 2.61 Segment IV 1.04 2.98 Segment V 0.83 6.2 (Tolerance ±0.01)

[0036] The material thickness ratio diu/dau of the subsegment UA in the preferred sample embodiment shown is 1.02 to 1.04, i.e., the thickness of the disc changes only slightly between the outer end and the inner end of the subsegment. Also in the third segment A.sub.III the material thickness da.sub.III increases only slightly to diiii from the outer end to the inner end, the material thickness ratio here being between 1.01 and 1.03. In segment A.sub.IV likewise absolutely no excessive increase in thickness is found between the thickness at the outer end da.sub.IV and the thickness at the inner end da.sub.V, the ratio di.sub.IV/di.sub.III being between 1.03 and 1.05, yet still the segment A.sub.IV has a substantial material thickening 15 between its two ends, whose thickness is 1.1 to 1.3 times the material thickness at the outer end da.sub.IV of the fourth segment A.sub.IV. This thickening of the material takes into account the fact that the wheel disc experiences greater stresses in this region than for example in the segments lying closer to the hub fitting flange.

[0037] The wheel disc according to the invention can be produced on a flow forming machine by flow forming of a metallic, i.e., steel blank under elongation of a preformed marginal region adjoining the clamped hub fitting flange 11, wherein this marginal region in the finished state of the wheel disc then forms the transition region and the disc edge. Between the measurement points shown in the drawings, at which the individual segments pass into one another, the course of the elongation during the fabrication is essentially continuous, while a thickness tolerance in the elongation region of ±3% is realistic. In general, the hub fitting flange after fabrication of the rough wheel disc by flow forming of a steel blank will be machined in a cutting process, especially on a lathe. If one defines the overall axial length as the length between the inside 16 of the hub fitting flange 11 and the inner end of the fifth segment A.sub.V adjoining the disc edge at the measurement point MP.sub.V and sets this overall axial length 17 equal to 100%, then the segments A.sub.I to A.sub.V extend across the following partial lengths TL.sub.I to V:

[0038] Segment A.sub.I

[0039] from the inside of the hub fitting flange: 9%-12% of the overall axial length 17.

[0040] Segment A.sub.II

[0041] from the inner end of segment A.sub.I to 43%-46% of the overall axial length.

[0042] Segment A.sub.III

[0043] from the inner end of segment A.sub.II to 70%-75% of the overall axial length.

[0044] Segment A.sub.IV

[0045] from the inner end of segment A.sub.III to 93%-97% of the overall axial length.

[0046] and Segment A.sub.V

[0047] from the inner end of segment A.sub.IV to the start of the disc edge (100% of the axial length).

[0048] If one forms the ratio of the material thickness at the transition points MP between the segments and the material thickness MPo of the machined hub fitting flange, the material thickness at the transition between segment A.sub.I and segment A.sub.II (measurement point MP.sub.I) is 50% to 55% of the material thickness MP.sub.0 of the hub fitting flange, the material thickness at the transition of segment A.sub.II to segment A.sub.III (MP.sub.II) is 45% to 52% of the material thickness MPo, at the transition of segment A.sub.III to A.sub.IV (measurement point MP.sub.III) it is 45% to 53% of the material thickness MP.sub.0, at the transition of segments A.sub.IV to A.sub.V (measurement point MP.sub.IV) it is 49% to 54% of the material thickness at the hub fitting flange MP.sub.0 and at the transition between segment V and the disc edge (MP.sub.V) it is 40% to 50% of the material thickness at the hub fitting flange.

[0049] In the region of the material thickening in the fourth segment the material thickness increases to 55% to 65% of the material thickness of the hub fitting flange MP.sub.0, while in the straight region of segment A.sub.II it is reduced to 45% to 50% of the material thickness MP.sub.0.

[0050] The special geometrical relations of the wheel disc in its transition region lead to a substantial material and weight saving as compared to known wheel discs of the same rated diameter and disc depth, which can amount to around 10% in the case of the disc of a wheel with 22.5 inch diameter.

[0051] In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiments. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.