Abstract:
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.

Description:
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. 
   (2) Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98 
   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. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       FIG. 1  is a cross-sectional view of a rim blank for producing a rim according to the present invention. 
       FIG. 2  is a side view, in cross section, of a circumferentially extending spoke region of the rim blank shown in  FIG. 1  with a first set of tooling above and below the spoke region. 
       FIG. 3  is a side view, in cross section, of the spoke region shown in  FIG. 2  after the tooling showing in  FIG. 2  has acted on the spoke region, and showing a second set of tooling above and below the spoke region. 
       FIG. 4  is a side view, in cross-section, of the spoke region shown in  FIG. 3  after the tooling in  FIG. 3  has acted on the spoke region. 
       FIG. 5  is a side view, in cross-section, of a circumferentially extending spoke region of the rim blank shown in  FIG. 1  with a third set of tooling above and below the spoke region. 
       FIG. 6  is a side view, in cross section, of the spoke region shown in  FIG. 5  after the tooling in  FIG. 5  has acted on the spoke region. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , a rim blank indicated at  10  comprises a circumferentially extending spoke region or spoke bed  12 , two opposed brake surfaces  14  and two opposed side walls  16  extending between the spoke bed  12  and the brake surfaces  14 . A transverse flange or upper web  18  extends between the upper portions of the extrusion  10 , adjacent to the brake surfaces  14 . An access hole, indicated at  19 , is formed in the transverse flange or upper web  18 . The access hole  19  provides tooling access that is required in some of the methods described below. Tire flanges  20  extend upwardly from the transverse flange  18  and terminate in tire bead hooks  22 . The spoke region  12  has an outer or lower surface  24  and an inner or upper surface  26 . 
   In  FIG. 2 , tooling is shown for upsetting metal in a portion of the spoke region, in the vicinity of a spoke hole (not shown in  FIG. 2 ) to be formed in the rim blank  10  ( FIG. 1 ). An anvil  30  is positioned below the spoke region  12  and it has a recess with a low point  32 . The anvil recess is configured to receive and support the spoke region  12 , specifically, to support the outside or lower surface  24  of the spoke region  12 . According to the method of the present invention, the anvil  30  and the spoke region  12  are brought together until the outside surface  24  of the spoke region  12  is firmly supported in the recess of the anvil  30 . With the spoke region  12  seated on the anvil  30 , a tool, indicated generally at  33 , is brought into contact with the inner surface  26  of the spoke region  12 . The tool  33  comprises a central plunger  34  and a forming collar  36  therearound. The forming collar  36  comprises a circumferential shoulder  38  and a forming cavity  40  at its lower end. 
   As the tool  33  advances towards the anvil, the shoulder  38  and the plunger  34  contact the inner surface  26  of the spoke region  12  which is then held captive between the tool  33  and the anvil  30 . The central plunger  34  is then advanced beyond the shoulder  38  and into the material constituting the spoke region  12 , thereby upsetting material outwardly from the plunger  34 . As the plunger  34  advances, the anvil  30  and the shoulder  38  cooperate to cause upset material to move into the cavity  40 . There is simply no other place for the upset material to go. It is preferred that the plunger  34  have a diameter corresponding with the diameter desired for a spoke hole and that the advancement of the plunger  34  be stopped before the plunger  34  reaches the anvil  30 , thereby producing a modified spoke region  12 ′ ( FIG. 3 ) with a thickened annular region  42  surrounding a spoke hole pre-form indicated at  44 . The outer surface  24  of the spoke region  12 ′ corresponds with the outer spoke surface  24  of the spoke region  12  because the anvil  30  prevents deformation of the outer surface  24  during the time that the tool  33  is acting on the spoke region  12 . The inner surface  26  of the spoke region  12  is transformed by the tool  33  into the inner surface  26 ′ shown in  FIG. 3  that includes the raised or thickened annular portion  42 . 
   A punch  46  is shown in  FIG. 3  poised to complete the formation of a spoke hole that is indicated at  48  in  FIG. 4 . The punch  46  is operable to remove a small, thin web of material  50  that remains in the spoke region  12 ′ below the spoke hole pre-form  44 . The punch  46  cooperates with an anvil  52  that includes an annular shoulder  54  surrounding a bore indicated at  56 . The outer surface  24  of the spoke region  12 ′ is brought into contact with the anvil  52  so that the shoulder  54  is centered around the spoke hole pre-form  44 . The punch  46  is advanced towards the anvil  52 , into the spoke hole pre-form  44  and through the thin web  50 , thereby removing the thin web  50  and producing the spoke hole indicated at  48  in  FIG. 4 . The punch  46  includes a shoulder  58  that forms a seat  60  around the spoke hole  48  for receiving a spoke head (not shown) or a spoke nipple (not shown) or the like. The punch  46  is operable to transform the inner surface  26 ′ ( FIG. 3 ) into the finished inner surface  26 ″ ( FIG. 4 ). 
   Referring now to  FIG. 4 , the completed spoke region  12 ″ has an outer surface  24  corresponding with the outer surface  24  of the spoke region  12  ( FIGS. 1 through 3 ), a spoke hole indicated at  48 , a thickened, internally raised annular region  42 ″ and a seat  60  formed in the annular region  42 ″. The annular region  42 ″ serves to reinforce the spoke region  12 ″ around the spoke hole indicated at  48 . On either side of the annular region  42 ′, as seen in  FIG. 4 , the spoke bed has the same thickness as the spoke bed  12  shown in  FIGS. 1 and 2 . Moreover, the outer surface  24  of the spoke region  12 ″ gives no indication that the area immediately surrounding the spoke hole indicated at  48  is reinforced by the thickened annular region  42 ′ because it extends inwardly from the inner surface  26 ″ and is not seen from the outside of the rim blank  10 . 
   Referring now to  FIGS. 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. 
   In  FIG. 5 , tooling is shown for upsetting metal in a portion of a spoke region  62  of a rim blank (not shown). Actually, half of the tooling and half of the spoke region  62  are 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 tool  64  and a lower punch tool  66 . The upper punch tool  64  includes an annular shoulder  68  surrounding a cavity indicated at  70 , which is defined by a forming surface  72  in an outer tool member  74 . A punch  76  is centrally located in the outer tool member  74  for reciprocating movement relative to the outer tool member  74 . The lower punch tool  66  comprises an outer tool member  78  and a punch  80  centrally located in the outer tool member  78  for reciprocating movement relative to the outer tool member  78 . A forming surface  82  is provided on the outer tool member  78 . 
   From the positions shown in  FIG. 5 , the upper punch tool  64  and the lower punch tool  66  are advanced towards each other to forge or upset the material of the spoke region  62  that is between the upper and lower punch tools  64  and  66 , until the spoke region  62  has assumed the configuration shown for modified spoke region  62 ′ as shown in  FIG. 6 . At that point, there will be a slug of material (not shown) between the punch  76  and the punch  80  which has to be removed in order to complete the formation of a spoke hole  84  ( FIG. 6 ) in the spoke region  62 ′. This is accomplished by retracting the punch  80  away from the spoke region  62  and advancing the punch  76  towards and through the spoke region  62  while maintaining the outer tool member  74  and the outer tool member  78  pressed tightly against an upper surface  86  and a lower surface  88 , respectively, of the spoke region  62 . 
   Referring now to  FIG. 6 , the completed spoke region  62 ′ comprises a modified upper surface  86 ′, a modified lower surface  88 ′, the spoke hole indicated at  84 , a thickened, internally raised annular region  90  and a seat  92  formed in the annular region  90 . On the modified lower surface  88 ′, there is a recessed portion  94  that is created by the action of the forming surface  82  of the outer tool member  78  on the lower punch tool  66 . On the modified upper surface  86 ′, the thickened annular region  90  serves to reinforce the spoke region  62 ′ around the spoke hole indicated at  84 . On either side of the annular region  90 , as seen in  FIG. 6 , the spoke bed or spoke region  62 ′ has the same thickness as the spoke bed or spoke region  62  shown in  FIG. 5 . In this embodiment, it is contemplated that the thickness of the spoke region  62 , before it is upset by the tools  64  and  66 , is greater than the thickness required for it in between spoke holes in the finished rim. Accordingly, after the spoke region  62  has been reworked into the modified spoke region  62 ′, material can be removed from the spoke region  62 ′ until the modified lower surface  88 ′ is made to be flush or substantially flush with the recessed portion  94  of the modified spoke region  62 ′ as indicated at  96 . 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 to  FIGS. 5 and 6 , it will be appreciated that an internally reinforced spoke hole can be produced even if the internally raised annular shoulder  90  is not thicker than the adjacent unworked portions of the spoke region  62 ′. 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 region  62 ′ after material is removed from the lower surface of the spoke region to make it flush, or substantially flush, with the recessed portion  94 . 
   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.