METHOD FOR MANUFACTURING A LIGHT-ALLOY HYBRID WHEEL INCLUDING A FRONT FLANGE AND A RIM

Abstract

A process for manufacturing a light-alloy hybrid wheel, implements the following separate operation phases: making a flange with an internal profile capable of constituting a tire bead seat; making a rim with, on one side, an outer profile capable of constituting a tire bead seat and, on the other side, a circular flank for assembly with a part of the flange; and assembling the flange with the rim, at the seat of said flange and the circular flank of the rim. The rim is made according to the following consecutive operations: an operation of manufacturing a circular flank; then an operation of expanding said circular flank to the size of the final rim in a single step; then an operation of cold or hot flospinning of said circular flank so as to obtain the rim in the final shape and profile thereof, comprising a shoulder only on the side that will not be welded to the flange.

Claims

1. A manufacturing process for a light-alloy hybrid wheel including a front flange and a rim, the process implementing the following separate operational phases: the flange is made with an internal profile constituting a tire bead seat; the rim is made with, on one side, an external profile constituting a tire bead seat, and on an other side, a circular flank for assembly with a part of the flange; the flange is assembled to the rim, at the seat of said flange and the circular flank of the rim. wherein the rim is made according to the following consecutive operations: an operation of manufacturing the circular flank; an operation of expanding said circular flank to a size of the final rim in a single step; an operation of cold or hot flospinning of the circular flank so as to obtain the rim in a final shape and profile thereof, comprising a shoulder only on a side that will not be welded to the flange.

2. The manufacturing process according to claim 1, wherein, in the manufacturing operation, the circular flank is made by hot or cold extrusion of a light alloy billet.

3. The manufacturing process according to claim 1, wherein, in the manufacturing operation, the circular flank is made by casting in a foundry.

4. The manufacturing process according to claim 1, wherein, in the manufacturing operation, the circular flank is made by powder sintering.

5. The manufacturing process according to claim 1, wherein the expansion operation and flospinning operation are cold-made.

6. The manufacturing process according to claim 1, wherein recesses are made in the seat of the flange, said recesses do not cover a circumference of the wheel, and have a U-shaped profile oriented in a direction of the circular flank of the rim.

7. The manufacturing process according to claim 1, wherein the flange is made by casting.

8. The manufacturing process according to claim 1, wherein the flange is made by forging.

9. The manufacturing process according to claim 14, wherein the flange is made by a dual casting and forging operation.

10. The manufacturing process according to claim 9, wherein the dual casting and forging operation comprises a casting operation of a foundry preform, a transfer of said foundry preform into a forging die, a forging operation of said foundry preform in order to obtaining the flask, and a deburring to obtain said flask.

11. The manufacturing process according to claim 9, wherein the dual casting and forging operation comprises a casting operation of a foundry preform, a storage of said foundry preform, a transfer of said foundry preform into an oven allowing the foundry preform to be heated, a transfer of said foundry preform into a forging die, a forging operation of said foundry preform in order to obtain the flask, and a deburring to obtain said flask.

12. The manufacturing process according to claim 6, wherein the flask is made by a dual casting and forging operation, and the recesses are formed within the tire bead seat on the flask during the casting operation.

13. The manufacturing process according to claim 1, wherein assembly of the rim and the flange is made by welding the circular flank of the rim and the flange by a single friction stir weld using a pin, in a position that allows access to both sides of the weld.

14. The manufacturing process according to claim 13 wherein the welding by a single friction stir weld is preceded by a machining operation of assembly zones.

15. The manufacturing process according to claim 13, wherein the welding by a single friction stir weld is followed by a machining operation on both sides of the weld in order to remove burring and any eventual defects at a bottom of the weld.

16. The manufacturing process according to claim 1, wherein assembly between the rim and the flange is made by a weld obtained by CMT (Cold Metal Transfer) technology.

17. The manufacturing process according to claim 1, wherein assembly between the rim and the flange is made by a weld obtained by laser or hybrid laser.

18. The manufacturing process according to claim 1, wherein assembly between the rim and the flange is made by a weld obtained by friction stir welding with cyclical movement between the rim and the flange.

Description

[0045] In order to associate the object of the illustrated invention in a non-limiting manner to the figures of the drawings,

[0046] FIG. 1 illustrates, according to the prior art, the implementation of a hybrid wheel in two parts with a rim part and a front flange part.

[0047] FIG. 2 illustrates the mounting of the tire on the rim with the positioning of the tire beads on the seats thereof.

[0048] FIG. 3 schematically illustrates, according to the prior art, the successive operations P1, P2, P3 in order to obtain the profile of the rim.

[0049] FIG. 4 schematically illustrates according to the invention the successive operations (obtaining a circular flank) P1, P2 (expansion of said circular flank), P3 (circular flank flospinning operation in order to obtain the profile of the rim).

[0050] FIG. 5 is a section view showing the profile of the rim according to the prior art, with a cavity formed on the rim.

[0051] FIG. 6 is a section view showing the profile of the rim according to the invention with the implementation of a single weld and the formation of recesses within one of the tire bead seats.

[0052] FIG. 7 is a front view of the hybrid wheel with an illustration of the recesses.

[0053] In order to render the object of the invention more concrete, it is herein described in a non-limiting manner and illustrated in the figures of the drawings.

[0054] As previously noted, the profile of the rim (1) is simplified by the execution of a single weld (5) for the assembly thereof with the flange (2). The rim (1) has a circular profile (1a) that acts as a seat for the tire but only on the inside of the wheel. The other profile (2a), acting as a seat for the tire, is implemented by the flange (2).

[0055] Hereinafter are highlighted certain features and advantages of the process of the invention.

[0056] FIGS. 3 and 4 illustrate the steps for obtaining the rim (1), according to the prior art and the invention respectively.

[0057] Within the scope of the invention, the rim (1) is made according to an operation (P1) of the production of a blank in the form of circular flank (1b); then an operation (P2) of expanding said circular flank (1b) to the dimensions of the final rim (1) in a single step; and finally an operation (P3) of cold or hot flospinning the circular flank (1b) so as to obtain the rim (1) in the final shape and profile thereof, with the remaining part of the circular flank (1b) on the side that will be welded to the flange (2) and a shoulder (1a) only on the side that will not be welded to the flange (2).

[0058] According to one preferred embodiment of the manufacturing operation (P1), a light-alloy billet is made, this billet is then transformed into a circular flank (1b) by hot or cold extrusion. In comparison to other known techniques, this allows a flank to be obtained (1b) that has very significant elongation. The flank expansion operation (1b) can thus be cold-made, i.e., at room temperature, which prevents warming before the expansion thereof. In addition, this greater elongation makes it possible to perform a cold flospinning operation (P3) after the cold expansion (P2) operation. The material of the rim (1) is subjected to significant hardening during the cold flospinning operation (P3). Before welding the flange (2), the rim (1) is therefore subjected to heat treatment (for example T6: solution heat treating and aging), during which the energy stored during the hardening is recuperated. This makes it possible to obtain fine recrystallized grains within the material of the rim (1). The microstructure thereof is therefore very fine and the mechanical features of the rim (1) are improved in comparison to a hot conditioning technique.

[0059] In the P3 step, in FIG. 3, the profile is illustrated of the rim (1) which is required in order to obtain the cavity (6) illustrated in FIG. 5 when the connection between the flange and rim is made using two welds. The simplified rim profile (1) can be seen in the P3 step of FIG. 4. This profile is in fact much simpler than that shown in the patent FR 2 981 605, illustrated in the P3 step of FIG. 3. This simplification is made possible due to the use of a single weld (5) implemented on the wheel of the invention. The external profile (1a) of the rim (1) in fact requires only one shoulder constituting a tire bead seat, instead of two. The result is a gain in cycle time and a simplification to the flospinning machine, which reduces costs. The other profile (2a), acting as a seat for the tire, is implemented by the flange (2).

[0060] Having a single weld (5) as shown in FIG. 6 also greatly simplifies the welding operation in comparison to double welding. Indeed, the welding is performed in one direction, perpendicular to the rim unlike the double welded wheel wherein the welds are in two different directions. It is no longer necessary to rotate the welding rod and the assembly is simplified and therefore less expensive, while there is a gain in cycle time and in the wear of the welding rod. The welding operation (5) is performed at the junction of the part (2B) of the flange (2) and of the circular flank (1b) of the rim (1).

[0061] In addition, having a single weld (5) makes it possible to access both sides of the weld. It is then possible to machine both sides of the weld. This machining which is commonly used with panels for aeronautics, makes it possible to remove any welding burrs and defects at the bottom of the weld that are often present with friction stir welding. These defects correspond to bad mixing of the alloy which creates non-welded seams at the bottom of the weld. The non-welded burrs or lips are defects that lead to the onset of cracking when there is fatigue stressing of the wheel. The removal thereof is therefore a great advantage from the point of view of the reliability of the process. Access to both sides of the weld also makes it possible to perform a frequency penetration test on the weld in order to ensure the stability of the welding process and to ensure the absence of defects. For a wheel with two welds, access to both sides of the weld is not assured. It is therefore necessary to section a wheel in order to perform this frequency test. In so far as this test is destructive, it results in the loss of part of the production and therefore an increase in costs for wheels with a closed cavity (6).

[0062] Laser and CMT welding, even though they are characterized by worse mechanical characteristics, may have an economic advantage. Indeed, laser welding can be competitive for very large runs and CMT welding requires a smaller investment. The mechanical characteristics of these welds are even better than those of MIG or TIG insofar as the thermally affected zone is reduced and fatigue resistance results are improved. They are still less resistant than FSW welds and requires more checking insofar as the welding is performed in the liquid phase. For the same mechanical performance of the part, a material thickness will be required, which will result in the wheel being slightly overweight. The use thereof will therefore be reflected in terms of cost and increased weight.

[0063] In a significant manner for the invention, the valve area is also greatly simplified. Indeed, for a wheel with two welds, the hole for the valve leads to an opening in the cavity (6). The majority of manufacturers do not want to have cavities within the wheels insofar as said opening leads to the possibility of the retention of water, gravel or other objects. A weld around the hole of the valve was therefore required in order to close the cavity (6) and to prevent water retention. This weld therefore represented an addition to the process presented in the patents FR 2981605 and EP 1230099, resulting in an additional cost.

[0064] In addition, making the wheel in two parts before welding makes it possible to implement more complex forms, that would not demoldable in a single part wheel. This technology makes it possible to implement recesses (7) at the flange (2), for example, in the form of cavities, as can be seen in FIG. 7. These recesses are made either in a foundry, or a forge, or during the foundry step of the “COBAPRESS” process. They are located at one of the tire bead seats (3) that has the flange (2) and that does not cover the circumference of the wheel. Indeed, these areas (8) are solid in order to increase the stiffness and resistance of the wheel. These solid areas (8) also greatly assist in fitting the tire. Indeed, without these solid areas the tire bead can be lodged within the cavities (7) during assembly. This tire bead can be difficult to position within the seat thereof during assembly and having solid areas creates a slope which greatly assists in this operation.

[0065] An area is also left without a recess in order to allow for the drilling and the positioning of the valve with a simple geometry (9), as can be seen from FIG. 7. The recesses (7), as shown in FIGS. 6 and 7, have a weld (5) side U-shaped profile.

[0066] Making recesses is not new. In practice, the implementation of these recesses during a forging or foundry step is economical insofar as it does not require a machining operation. This saves both cycle time and cost. The threshold value, i.e., the quantity of material involved with respect to useful material, is also reduced.

[0067] In practice and according to the invention, this is remarkable due to the combination of different phases of the process that on a practical level have a very large number of advantages over the prior art. It is therefore an optimization that has required significant research and development investments and that did not stem from the teaching of the prior art.