Bicycle wheel rim with internally reinforced spoke seats and method for producing them

Bicycle wheel rims with internally reinforced spoke seats are disclosed along with methods for producing them. The rims are produced from a rim blank with at least one circumferentially extending spoke attachment region that has a relatively uniform given thickness. Access holes are formed in an upper web of the rim blank and tooling is positioned above and below the spoke attachment region to form a reinforced spoke seat and a spoke hole therein. Material that is upset and moved from the location of the spoke hole is displaced into an annular region where it reinforces the spoke hole. Material in the vicinity of the spoke hole can be displaced towards the inside of the rim and material can be removed from the undisplaced portions of the spoke region leaving a reinforced area around the spoke hole.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates generally to rims for wheels for human powered vehicles such as bicycles, wheel chairs and the like, and especially to novel rims with reinforced spoke seats and methods for producing them.

A great deal of effort has been directed to reducing the weight of rims for wheels for human powered vehicles and especially bicycle wheel rims. Bicycle wheel rims are typically produced by extruding aluminum alloy or the like to produce a linear extrusion having a cross section corresponding with the finished rim, rolling the extrusion into a circular shape, cutting the extrusion to length and connecting the free ends with pins, plugs or welds. In a finished wheel, the greatest stresses on the rim are concentrated where spokes that support the rim relative the hub of the wheel are supported on or connected to the rim at spoke connection points or spoke seats. As a consequence, if a rim is uniformly shaped about its circumference, the areas between the spoke connection points will be thicker and heavier than they need to be in order for the spoke connection points along the rim to be strong enough to withstand the stresses they encounter. This means that the rim will be heavier than it needs to be. No small inventive effort has been directed at making rims lighter overall but reinforcing rims at spoke connection points and using inserts adapted to distribute the stresses on the rim that are caused by the spokes, thereby lightening the rim.

U.S. Pat. No. 6,402,256 discloses a rim with a nominal wall thickness in spoke boring zones and a wall thickness in intermediate zones between boring zones that is less than the nominal thickness. Between the boring zones and the intermediate zones, transitional zones of the rim wall have a thickness that varies progressively from the nominal thickness to the thickness of the intermediate zone. According to the patent, the rim is produced by producing a rim blank and machining portions of the outside surface of the rim wall to create the intermediate zones and the transitional sections, leaving the original, nominal thickness of the rim in the boring zones.

Other patents disclose rims with wall sections that are thickened to withstand the forces exerted on the rims by spokes under tension. For example, U.S. Pat. No. 6,283,557 discloses a rim with circumferential rings 68 of increased thickness in spoke attachment zones. U.S. Pat. No. 6,536,849 discloses a rim with sections of increased thickness where spokes are attached to the rim and an internal ridge that may strengthen the rim.

U.S. Pat. No. 6,234,580 discloses several embodiments of rims with reinforced spoke seats, including some that appear to be impossible to produce.

BRIEF SUMMARY OF THE INVENTION

The present invention is a bicycle wheel rim including reinforced spoke seats and methods for producing such rims. Rim blanks for use in the methods of the present invention can be produced by extruding a suitable alloy into a rim profile, rolling the extrusion, cutting the rolled extrusion to length and joining the free ends to produce a rim blank having at least one circumferentially extending spoke attachment region that has a relatively uniform given thickness. According to the invention, access holes are then formed in the rim opposite the spoke hole locations, for example, in an upper web of the rim, tooling is positioned above and below the spoke attachment region and the tooling is manipulated to form a reinforced spoke seat and a spoke hole therein.

Accordingly, it is an object of the present invention to provide an improved rim for bicycle wheels.

It is a further object of the invention to provide a simple method for producing an improved rim with a reinforced spoke seat.

It is a further object of the present invention to provide a rim having a circumferentially extending spoke region and having internally reinforced spoke seats therein.

It is yet a further object of the invention to provide a rim with reinforced spoke seats wherein the reinforcement is not visible from the outside of the rim.

These and other objects and advantages of the present invention will be fully appreciated by those skilled in the art upon reviewing the disclosures herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG. 1, a rim blank indicated at10comprises a circumferentially extending spoke region or spoke bed12, two opposed brake surfaces14and two opposed side walls16extending between the spoke bed12and the brake surfaces14. A transverse flange or upper web18extends between the upper portions of the extrusion10, adjacent to the brake surfaces14. An access hole, indicated at19, is formed in the transverse flange or upper web18. The access hole19provides tooling access that is required in some of the methods described below. Tire flanges20extend upwardly from the transverse flange18and terminate in tire bead hooks22. The spoke region12has an outer or lower surface24and an inner or upper surface26.

InFIG. 2, tooling is shown for upsetting metal in a portion of the spoke region, in the vicinity of a spoke hole (not shown inFIG. 2) to be formed in the rim blank10(FIG. 1). An anvil30is positioned below the spoke region12and it has a recess with a low point32. The anvil recess is configured to receive and support the spoke region12, specifically, to support the outside or lower surface24of the spoke region12. According to the method of the present invention, the anvil30and the spoke region12are brought together until the outside surface24of the spoke region12is firmly supported in the recess of the anvil30. With the spoke region12seated on the anvil30, a tool, indicated generally at33, is brought into contact with the inner surface26of the spoke region12. The tool33comprises a central plunger34and a forming collar36therearound. The forming collar36comprises a circumferential shoulder38and a forming cavity40at its lower end.

As the tool33advances towards the anvil, the shoulder38and the plunger34contact the inner surface26of the spoke region12which is then held captive between the tool33and the anvil30. The central plunger34is then advanced beyond the shoulder38and into the material constituting the spoke region12, thereby upsetting material outwardly from the plunger34. As the plunger34advances, the anvil30and the shoulder38cooperate to cause upset material to move into the cavity40. There is simply no other place for the upset material to go. It is preferred that the plunger34have a diameter corresponding with the diameter desired for a spoke hole and that the advancement of the plunger34be stopped before the plunger34reaches the anvil30, thereby producing a modified spoke region12′ (FIG. 3) with a thickened annular region42surrounding a spoke hole pre-form indicated at44. The outer surface24of the spoke region12′ corresponds with the outer spoke surface24of the spoke region12because the anvil30prevents deformation of the outer surface24during the time that the tool33is acting on the spoke region12. The inner surface26of the spoke region12is transformed by the tool33into the inner surface26′ shown inFIG. 3that includes the raised or thickened annular portion42.

A punch46is shown inFIG. 3poised to complete the formation of a spoke hole that is indicated at48inFIG. 4. The punch46is operable to remove a small, thin web of material50that remains in the spoke region12′ below the spoke hole pre-form44. The punch46cooperates with an anvil52that includes an annular shoulder54surrounding a bore indicated at56. The outer surface24of the spoke region12′ is brought into contact with the anvil52so that the shoulder54is centered around the spoke hole pre-form44. The punch46is advanced towards the anvil52, into the spoke hole pre-form44and through the thin web50, thereby removing the thin web50and producing the spoke hole indicated at48inFIG. 4. The punch46includes a shoulder58that forms a seat60around the spoke hole48for receiving a spoke head (not shown) or a spoke nipple (not shown) or the like. The punch46is operable to transform the inner surface26′ (FIG. 3) into the finished inner surface26″ (FIG. 4).

Referring now toFIG. 4, the completed spoke region12″ has an outer surface24corresponding with the outer surface24of the spoke region12(FIGS. 1 through 3), a spoke hole indicated at48, a thickened, internally raised annular region42″ and a seat60formed in the annular region42″. The annular region42″ serves to reinforce the spoke region12″ around the spoke hole indicated at48. On either side of the annular region42′, as seen inFIG. 4, the spoke bed has the same thickness as the spoke bed12shown inFIGS. 1 and 2. Moreover, the outer surface24of the spoke region12″ gives no indication that the area immediately surrounding the spoke hole indicated at48is reinforced by the thickened annular region42′ because it extends inwardly from the inner surface26″ and is not seen from the outside of the rim blank10.

Referring now toFIGS. 5 and 6, a second method for producing a rim with a reinforced spoke hole will now be described. Like the method described previously, this method produces a rim blank with an internally reinforced spoke hole wherein the reinforcement is not apparent when viewing the rim blank from the outside.

InFIG. 5, tooling is shown for upsetting metal in a portion of a spoke region62of a rim blank (not shown). Actually, half of the tooling and half of the spoke region62are shown because the other halves are mirror images of the halves that are shown with symmetry about an axis A. The tooling comprises an upper punch tool64and a lower punch tool66. The upper punch tool64includes an annular shoulder68surrounding a cavity indicated at70, which is defined by a forming surface72in an outer tool member74. A punch76is centrally located in the outer tool member74for reciprocating movement relative to the outer tool member74. The lower punch tool66comprises an outer tool member78and a punch80centrally located in the outer tool member78for reciprocating movement relative to the outer tool member78. A forming surface82is provided on the outer tool member78.

From the positions shown inFIG. 5, the upper punch tool64and the lower punch tool66are advanced towards each other to forge or upset the material of the spoke region62that is between the upper and lower punch tools64and66, until the spoke region62has assumed the configuration shown for modified spoke region62′ as shown inFIG. 6. At that point, there will be a slug of material (not shown) between the punch76and the punch80which has to be removed in order to complete the formation of a spoke hole84(FIG. 6) in the spoke region62′. This is accomplished by retracting the punch80away from the spoke region62and advancing the punch76towards and through the spoke region62while maintaining the outer tool member74and the outer tool member78pressed tightly against an upper surface86and a lower surface88, respectively, of the spoke region62.

Referring now toFIG. 6, the completed spoke region62′ comprises a modified upper surface86′, a modified lower surface88′, the spoke hole indicated at84, a thickened, internally raised annular region90and a seat92formed in the annular region90. On the modified lower surface88′, there is a recessed portion94that is created by the action of the forming surface82of the outer tool member78on the lower punch tool66. On the modified upper surface86′, the thickened annular region90serves to reinforce the spoke region62′ around the spoke hole indicated at84. On either side of the annular region90, as seen inFIG. 6, the spoke bed or spoke region62′ has the same thickness as the spoke bed or spoke region62shown inFIG. 5. In this embodiment, it is contemplated that the thickness of the spoke region62, before it is upset by the tools64and66, is greater than the thickness required for it in between spoke holes in the finished rim. Accordingly, after the spoke region62has been reworked into the modified spoke region62′, material can be removed from the spoke region62′ until the modified lower surface88′ is made to be flush or substantially flush with the recessed portion94of the modified spoke region62′ as indicated at96. This removal of material can be accomplished mechanically, as by abrasion or cutting or by other suitable means known in the art. It is preferred that, when the removal of material is completed, the lower surface of the spoke region has a uniform surface that does not give away the fact that the spoke hole is reinforced internally.

In the embodiment described above with reference toFIGS. 5 and 6, it will be appreciated that an internally reinforced spoke hole can be produced even if the internally raised annular shoulder90is not thicker than the adjacent unworked portions of the spoke region62′. In other words, if the upper and lower punch tools are configured so that they indent but do not thicken the annular region around what will become the spoke hole, that annular region will be thicker and thus reinforced, by comparison with adjacent portions of the spoke region62′ after material is removed from the lower surface of the spoke region to make it flush, or substantially flush, with the recessed portion94.

The foregoing detailed description sets forth the best mode known to the inventor for carrying out the invention and is intended to enable one of ordinary skill in the art to practice the invention. In practice, however, the invention is not necessarily limited to the exact details of the embodiments described above but is susceptible of variations and departures therefrom within the spirit and scope of the invention as it is defined in the appended claims.