Patent Publication Number: US-2005123378-A1

Title: Decorative capped wheel nut or bolt assembly and method

Description:
RELATED APPLICATION  
      This application is a continuation of application Ser. No. 10/303,564, filed Nov. 25, 2002, which is a continuation-in-part of application Ser. No. 09/828,662, filed Apr. 5, 2001, now abandoned. The disclosure of application Ser. No. 10/303,564 is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION  
      This invention relates generally to wheel nuts or bolts for securing a vehicle wheel, i.e., a tire and rim, on a motor vehicle. It relates particularly to a decorative capped wheel nut or bolt assembly and assembly method.  
     BACKGROUND OF THE INVENTION  
      Decorative capped wheel nuts and bolts are well-known in the automotive art. A decorative capped wheel nut assembly, for example, conventionally comprises a nut insert and a decorative cap which is fastened to the insert by welding, crimping or with an adhesive. Examples of these constructions are illustrated in various prior art patents, including the Toth U.S. Pat. No. 4,955,773, the Bydalek U.S. Pat. No. 5,772,377, the Chaivre U.S. Pat. No. 4,018,133, and U.S. Pat. No. 4,056,862, the Baltzell U.S. Pat. No. 4,764,070 and the Somers et al. U.S. Pat. No. 6,036,420, for example. It is also known to form threads in a cap and in a lug nut and thread the cap onto the nut. See the Nolan et al. U.S. Pat. No. 5,180,266 in this regard.  
      All nut or bolt and cap assemblies described in the prior art require relatively complex fastening structures, assembly procedures and/or additional components. Assemblies made by welding require expensive and sophisticated equipment for implementation of production. Practical options for plating the inserts are limited where welding is employed, placing welded designs at a disadvantage for achieving high corrosion resistance. Crimped fastening designs require the addition of components, i.e., a sealant or O-ring, which complicates automated assembly. The use of adhesives for fastening causes similar problems. Because of the nature of welding, or the use of additional components, production rates for these assemblies processes are low.  
     SUMMARY OF THE INVENTION  
      An object of the invention is to provide an improved decorative capped wheel nut or wheel bolt assembly.  
      Another object is to provide a decorative capped wheel nut or wheel bolt assembly wherein the decorative cap is secured to the nut or bolt insert without welding, applying an adhesive, or using a sealant or O-ring.  
      Yet another object is to provide a decorative cap and insert assembly which is simpler and less expensive, but just as reliable, as prior art assemblies.  
      Still another object is to provide a new and improved method of assembling a decorative cap and nut or bolt insert.  
      The foregoing and other objects are realized in an insert and cap assembly wherein the components are securely fastened together by creating an interference fit between the cap and the insert. Specifically, the insert includes at least one section with a plated, coated or plated and coated circular cylindrical outer surface. The cap has a corresponding segment with a circular cylindrical inner surface which has an inside diameter 0.010 to 0.030 inches smaller than the outside diameter of the coated circular cylindrical outer surface. The cap is fabricated of material which makes it radially deformable both plastically and elastically. The insert is press fit into the cap, driving the cap&#39;s cylindrical inner surface over the insert&#39;s coated circular cylindrical outer surface. Radial plastic and elastic deformation of the cap occurs. A 0.002 to 0.006 inches interference fit is formed around the interfering circular cylindrical surfaces by the elastic deformation of the cap.  
      In most applications of the invention, a straight cylindrical interference fit is sufficient to retain the cap on the nut insert permanently. In another aspect of the invention the cap rim may also be crimped, however. In yet another aspect, the cap rim may be thickened and snap behind a shoulder on the insert.  
      The improved method of retaining a cap on the insert body requires only two components, the cap and the insert, thus reducing the extra expense of an additional component and the complexities of introducing this extra component into the assembly process. It also allows the use of all types of coating, plating and coating or plating alone on the insert, which is not possible using current welding assembly methods. Further cost savings may be achieved with higher assembly rates using simple hydraulic, pneumatic, or mechanical press equipment.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention, including its construction and method of operation, is illustrated more or less diagrammatically in the drawings, in which:  
       FIG. 1  is a side elevational view of a first embodiment of the invention in a decorative capped wheel nut assembly;  
       FIG. 2  is a top plan view of the wheel nut assembly seen in  FIG. 1 ;  
       FIG. 3  is a side elevational view of the nut insert for the decorative capped wheel nut assembly seen in  FIGS. 1 and 2 ;  
       FIG. 4  is a top plan view of the nut insert seen in  FIG. 3 ;  
       FIG. 5  is a bottom plan view of the cap for the decorative capped wheel nut assembly seen in  FIGS. 1 and 2 ;  
       FIG. 6  is a sectional view taken along line  6 - 6  of  FIG. 2 ;  
       FIG. 7  is a diagrammatic illustration of an insert being press fit into a cap in a mechanical press;  
       FIG. 8  is a side view, partially in elevation and partially in section, of a second embodiment of the capped invention;  
       FIG. 9  is a top plan view of the capped wheel nut assembly seen in  FIG. 8 ;  
       FIG. 10  is a split elevational/sectional view, similar to  FIG. 8 , of a third embodiment of the capped wheel nut assembly invention;  
       FIG. 11  is a top plan view of the capped wheel nut assembly seen in  FIG. 10 ;  
       FIG. 12  is a split elevational/sectional view, similar to  FIG. 8 , of a fourth embodiment of the invention, a decorative capped wheel bolt assembly;  
       FIG. 13  is a top plan view of the capped wheel bolt assembly seen in  FIG. 12 ;  
       FIG. 14  is a split elevational/sectional view, similar to  FIG. 8 , of a fifth embodiment of the invention, another decorative capped wheel bolt assembly;  
       FIG. 15  is a top plan view of the capped wheel bolt assembly seen in  FIG. 14 ;  
       FIG. 16  is a split elevational/sectional view, similar to  FIG. 8 , of a sixth embodiment of the invention, another capped wheel nut assembly;  
       FIG. 17  is a top plan view of the capped wheel nut assembly seen in FIG.  16 ;  
       FIG. 18  is a split elevational/sectional view, similar to  FIG. 8 , of a seventh embodiment of the invention, yet another capped wheel nut assembly;  
       FIG. 19  is a top plan view of the capped wheel nut assembly seen in  FIG. 18 ;  
       FIG. 20  is an enlarged portion of the assembly seen in  FIG. 18 ; and  
       FIG. 21  is an enlarged portion of an assembly similar to that of  FIG. 20 , showing a variation of the seventh embodiment assembly. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring now to the drawings, and particularly to  FIGS. 1-6 , a decorative capped wheel nut assembly comprising a first embodiment of the present invention is seen generally at  10 . The wheel nut assembly  10  includes a nut insert  12  and a decorative cap  14  fastened securely together by a method embodying features of the invention.  
       FIGS. 1, 2  and  6  illustrate the wheel nut  10  assembly, i.e., an assembled nut insert  12  and cap  14 .  FIGS. 3 and 4  illustrate a nut insert  12  separately.  FIG. 5  illustrates a cap  14  separately (end view).  
      As seen in  FIGS. 3, 4  and  6 , the nut insert  12  comprises a body  21  having a cylindrical bore  23  extending axially through it from a hex-shaped section  24  on one end to a frusto-conical base  25  on the other. The nut insert  12  is commonly referred to as a hex-nut insert and is fabricated in a conventional manner of carbon steel. The frusto-conical base  25  is adapted to seat in a conventional manner in a wheel rim aperture (not shown) to fasten the wheel rim to a vehicle wheel stud (not shown). The bore  23  is internally threaded at its inner end  27  to receive the stud.  
      The nut insert  12  is coated in a conventional manner to prevent oxidation of exposed areas. In the embodiment illustrated a coating of GEOMET brand coating material available from Metal Coatings International, Inc. of Chardon, Ohio, is applied. GEOMET is a coating comprised mainly of overlapping zinc and aluminum flake in an inorganic binder, and is chromium free. It is applied over the entire insert  12  to a thickness of 0.001 inches.  
      Between the hex-shaped section  24  and the frusto-conical base  25 , the insert body  21  has two cylindrical body sections  31  and  33 . The section  31  of the illustrated insert body  21  has a cylindrical outer (coated) surface  35  with an outside diameter (OD) of 0.930 inches. The surface  35  has an axial length of 0.130 inches. The section  33  has a cylindrical outer (coated) surface  39  with an OD of 0.955 inches. The surface  33  has an axial length of 0.0625 inches. A radially extending shoulder  41  is formed between the two cylindrical surfaces  31  and  33 .  
      As seen in  FIGS. 2, 5  and  6 , the cap  14  comprises three axially aligned wall segments; a dome-shaped end wall segment  51 , a hex cross-section side wall segment  53  and a circular cylindrical side wall segment  55 . The configuration and internal cross-sectional dimensions of the hex-shaped side wall segment  53  are such that it slips easily over the coated, hex-shaped section  24  of the insert body. According to the invention, however, as will hereinafter be further discussed, the internal cross-sectional dimension of the circular cylindrical side wall segment  55  is such that a predetermined elastic interference fit is formed between the inner surface  57  of the wall segment  55  and the coated cylindrical outer surface  35  of the insert body  21  when the cap  14  is press fit onto the insert  12 .  
      The cap  14  is fabricated of stainless steel sheet with a nominal thickness of  0 . 018  to 0.020 inches. The inside diameter (ID) of the cylindrical wall segment  55  is preferably 0.910 inches. When the cap  14  is pressed onto the insert  12 , the cylindrical wall segment  55  undergoes both plastic and elastic deformation. The portion of deformation that is plastic serves to allow a reasonable manufacturing tolerance for both components. The elastic deformation results in tensile hoop stresses in the cap  14  and constitutes the mechanism by which the cap  14  is retained on the insert  12 . The resulting interference fit is approximately 0.0025 inches around the interfering circular cylindrical surfaces as a result of elastic deformation, but can vary with changes in cap wall thickness or mechanical properties of the cap material.  
       FIG. 7  illustrates the assembly of a nut insert  12  into a cap  14  in a simple mechanical press P. The press P comprises a fixed die Dl in which the cap  14  is seated. A movable die D 2  receives the insert  12  and drives it downwardly onto the cap  14  under the influence of pressure exerted in a conventional manner by the mechanical press P. The fixed die D 1  receives the cap  14  in a well W. The well W is dimensioned to permit the radial expansion of the cylindrical side wall segment  55  which takes place in the cap  14  as the insert  12  is press fit into the cap  14 .  
      Referring now to  FIGS. 8 and 9 , a decorative capped wheel nut assembly comprising a second embodiment of the invention is seen generally at  110 . The assembly  110  includes a nut insert  112  and a decorative cap  114  fastened together according to the present invention.  
      The nut insert  112  comprises a body  121  having a cylindrical bore  123  extending axially through it from a cylindrical section  131  on one end to a frusto-conical base  125  on the other. The base  125  is adapted to seat in a wheel rim aperture (not shown). The bore  123  is internally threaded at  127 . The insert  112  is coated in a manner previously discussed.  
      Between the conical base  125  and the cylindrical section  131 , there is a hex-shaped section  124 . The hex-shaped section  124  corresponds to the hex section  24  in the insert body  21  of the assembly  10 .  
      The axially outer, or end cylindrical section  131 , has a coated cylindrical outer surface  135  with an OD of 0.660 inches. The surface  135  has an axial length of 0.190 inches.  
      As seen in  FIG. 8  the cap  114 , which is again formed from stainless steel sheet, comprises four axially aligned segments; a dome shaped end wall segment  151 , a cylindrical side wall segment  155 , a hex-shaped side wall segment  153  and a frusto-conical lip  152 . The configuration and internal cross-sectional dimensions of the hex-shaped side wall segment  153  are such that it slips easily over the coated hex-shaped section  124  in the insert body  121 .  
      The ID of the cylindrical wall segment  155  is 0.640 inches. When the cap  114  is pressed onto the insert  112 , the cylindrical wall segment  155  undergoes both plastic and elastic deformation in the manner hereinbefore discussed with relation to the cap  14 . The elastic deformation constitutes the mechanism by which the cap  114  is retained on the insert  112 . The resulting interference fit is approximately 0.0025, again varying with changes in cap wall thickness or mechanical properties of the cap material.  
      Referring now to  FIGS. 10 and 11 , a decorative capped wheel nut assembly comprising a third embodiment of the invention is seen generally at  210 . The assembly  210  includes a nut insert  212  and a decorative cap  214  fastened together according to the invention.  
      The nut insert  212  comprises a body  221  having a cylindrical bore  223  extending axially through it from a cylindrical section  231  on one end to a frusto-conical base  225  on the other. The base  225  is adapted to seat in a wheel rim aperture (not shown). The bore  223  is internally threaded at  227 . Like the inserts  12  and  112 , the insert  212  is coated.  
      Between the conical base  225  and the end cylindrical section  231  there is a hex-shaped section  224 . The hex-shaped section  224  corresponds to the section  24  in the insert body  21  of the insert  12 .  
      Between the hex-shaped section  224  and the frusto-conical base  225 , the insert body  221  has two cylindrical body sections  233  and  234 . The axially outer cylindrical section  233  of the two has a coated cylindrical outer surface  235  with an outside diameter (OD) of 0.930 inches. The surface  235  has an axial length of 0.130 inches. A radially extending shoulder  241  is formed between the two cylindrical surfaces  233  and  234 .  
      The end cylindrical section  231  has a coated cylindrical outer surface  236  with an OD of 0.660 inches. The surface  236  has an axial length of 0.190 inches.  
      As seen in  FIG. 11 , the cap  214 , again formed of stainless steel sheet, comprises four axially aligned segments; a dome shaped end wall segment  251 , an end circular cylindrical side wall segment  255 , a hex-shaped side wall segment  253  and a circular cylindrical side wall segment  252 . The configuration and internal cross-sectional dimensions of the hex-shaped side wall segment  253  are such that it will slip freely over the coated hex-shaped section  224  in the insert body  221 .  
      The ID of the cylindrical wall segment  255  is 0.640 inches. When the cap  214  is pressed onto the insert  212 , the cylindrical wall segment  255  undergoes the aforedescribed plastic and elastic deformation as it is forced over the coated cylindrical surface  236 . The resulting interference fit is again approximately 0.0025.  
      The ID of the cylindrical side-wall segment  252  is 0.910 inches. As such, an interference fit of 0.0025 inches is effected at the same time between the side-wall segment  252  and the coated outer surface  235  of the end cylindrical section  231 .  
      In  FIGS. 12-15  the invention is seen in the context of a wheel bolt rather than a wheel nut. Referring specifically to  FIGS. 12 and 13 , a decorative capped wheel bolt assembly comprising a fourth embodiment of the invention is seen generally at  310 . The assembly  310  includes a bolt insert  312  and a decorative cap  314 .  
      The bolt insert  312  comprises a bolt body  321  fabricated of carbon steel in a conventional manner. The body  321  includes a hex-shaped section  324  at one end and an externally threaded base  327  at the opposite end. The insert  312  is coated in a manner previously discussed.  
      Between the hex-section  324  and the threaded base  327 , a circular cylindrical section  331  and a frusto-conical section  333  are formed. The circular cylindrical section  331  has a coated cylindrical outer surface  335 . The OD of surface  335  is 0.895 inches. The surface  335  has an axial length of 0.165 inches.  
      The frusto-conical section  333  is adapted to seat in a wheel rim aperture (not shown) to fasten the wheel rim to a vehicle wheel. The threaded base  327  of the insert  312  threads into the wheel hub in a well known manner.  
      The cap  314 , again formed from stainless steel sheet, comprises three axially aligned segments, a dome shaped end wall segment  351 , a hexshaped side wall segment  353  and a cylindrical side wall segment  355 . The configuration and internal cross-sectional dimensions of the hex-shaped side wall segment  353  are such that it slips easily over the coated hex-shaped section  324  in the insert body  321 .  
      The ID of the cylindrical wall segment  355  is 0.875 inches. When the cap  314  is pressed onto the insert  312 , the cylindrical wall segment  355  undergoes the aforedescribed plastic and elastic deformation as it is forced over the coated surface  335  on the bolt body  321 . The resulting interference fit is again approximately 0.0025 inches.  
      Referring now to  FIGS. 14 and 15 , a decorative capped wheel bolt assembly comprising a fifth embodiment of the invention is seen generally at  410 . The assembly  410  also includes a bolt insert  412  and a decorative cap  414 .  
      The bolt insert  412  comprises a bolt body  421  fabricated of carbon steel in a conventional manner. The body  421  includes a hex-shaped section  424  near one end and an externally threaded base  427  at the opposite end. The insert  412  is coated in a manner previously discussed.  
      Axially outwardly of the hex-section  424 , the insert  412  includes a circular cylindrical section  431 . The circular cylindrical section  431  has a coated cylindrical outer surface  435 . The OD of surface  435  is 0.615 inches. The surface  435  has an axial length of 0.150 inches.  
      The insert  412  also has a spherical section  433  adapted to seat in a conventional manner in a wheel rim aperture (not shown) to fasten the wheel rim to a vehicle wheel. The threaded base  427  of the insert  412  threads into the wheel in a well known manner.  
      The cap  414 , again formed from stainless steel sheet, comprises three axially aligned segments; a dome shaped end wall segment  451 , a cylindrical side wall segment  455 , a hex-shaped side wall segment  453  and a flared lip  456 . The configuration and internal cross-sectional dimensions of the hex-shaped side wall segment  453  are such that it slips easily over the coated hex-shaped section  424  in the insert body  421 .  
      The ID of the cylindrical wall segment  455  is 0.595 inches. When the insert  412  is pressed into the cap  414 , the cylindrical wall segment  455  undergoes the aforedescribed plastic and elastic deformation. As it is forced over the coated cylindrical surface  435  on the bolt body  421 , an interference fit of approximately 0.0025 inches is effected around the coated surface  435 .  
       FIGS. 16 and 17  illustrate yet a sixth embodiment of a capped wheel nut assembly embodying features of the invention at  510 . The assembly  510  includes a nut insert  512  and a decorative cap  514 .  
      The nut insert  512  comprises a body  521  having a cylindrical bore  523  extending axially through it from a hex-shaped section  524  on one end to a frusto-conical base  525  on the other. The base  525  is adapted to seat in a wheel rim aperture (not shown). The bore  523  is internally threaded at  527 . Like the inserts  12  and  112 , the insert  512  is coated.  
      Between the hex-shaped head  524  and the frusto-conical base  525 , the insert body  521  has a body section  533 . The body section  533  of the illustrated insert body  521  has a coated cylindrical outer surface  535  with an OD of 1.160 inches and an axial length of 0.130 inches. Below the cylindrical body section surface  535 , and above the frusto-conical base  525 , there is an undercut  534 .  
      The cap  514  comprises three axially aligned wall segments; a dome-shaped end wall segment  551 , a hex cross-section side wall segment  553 , a circular cylindrical side wall segment  555  and a crimp section  556 . The configuration and internal cross-sectional dimensions of the hex-shaped side wall segment  553  are such that it slips easily over the coated, hex-shaped section  524  of the insert body (before the inward crimp section  556  is formed). The internal cross-sectional dimension of the circular cylindrical side wall segment  555  is such that a predetermined interference fit is formed between the inner surface  557  of the wall segment  555  and the coated cylindrical outer surface  535  of the insert body  521  when the cap  514  is press fit onto the insert  512 .  
      The cap  514  is fabricated of stainless steel sheet with a nominal thickness of 0.018 to 0.020 inches. The inside diameter (ID) of the cylindrical wall segment  555  is preferably 1.140 inches. The cap  514  is pressed onto the insert  512  and the cylindrical wall segment  555  undergoes plastic and elastic deformation. The resulting interference fit is approximately 0.0025.  
      In this embodiment of the invention, the crimp section  556  is formed inwardly after the insert  512  is press fit into the cap  514  in the aforedescribed manner. Crimping may be accomplished as a continuation of the press-fit operation. The crimp section  556  is crimped into engagement with the undercut  534  on the insert body  521 . The crimp feature is offered as an option where the assembly  510  may be subject to extreme wrenching abuse, and assures that it will remain intact under such conditions. It also provides a pleasing decorative appearance to the assembly. The interference fit and the crimp then both serve to hold the cap  514  securely on the insert  512  with the interference fit serving the further function of blocking the entry of moisture at the juncture of surfaces  535  and  557 .  
       FIGS. 18-20  illustrate a seventh embodiment of a capped wheel nut assembly embodying features of the invention at  610 . The assembly  610  includes a nut insert  612  and a decorative cap  614 .  
      The nut insert  612  comprises a body  621  having a cylindrical bore  623  extending axially through it from a hex-shaped section  624  on one end to a frusto-conical base  625  on the other. The base  625  is adapted to seat in a wheel rim aperture (not shown). The bore  623  is internally threaded at  627 . Like the inserts  12  and  112 , the insert  612  is coated.  
      Between the hex-shaped head  624  and the frusto-conical base  625 , the insert body  621  has a body section  633 . As best seen in  FIG. 20 , the body section  633  of the illustrated insert body  621  has a coated cylindrical surface  635  adjacent the base  625  which has an axial length of 0.180 inches. The coated cylindrical surface  635  includes a first cylindrical surface  641  having an OD of 0.910 inches and an axial length of 0.070 inches and a second cylindrical surface  642  having an OD of 0.890 inches and an axial length of 0.110 inches. An annular shoulder  643  having a width of 0.010 inches is, thus, formed between the first and second surfaces  641  and  642 .  
      The cap  614  comprises three axially aligned wall segments; a dome-shaped end wall segment  651 , a hex cross-section side wall segment  653  and a generally circular cylindrical side wall segment  655 . The configuration and internal cross-sectional dimensions of the hex-shaped side wall segment  653  are such that it slips easily over the coated, hex-shaped section  624  of the insert body.  
      The circular cylindrical side wall segment  655  includes a lip  656  folded back inside the wall segment. As seen in  FIG. 20 , the lip  656  doubles the wall segment  655  thickness at its outer end, as seen at  657 . Coextensive with the lip  656 , the wall segment  655  is also formed slightly outwardly so that the double thickness portion  657  of it is effectively centered under the segment  655 .  
      The cap  614  is fabricated of stainless steel sheet with a nominal thickness of 0.018 to 0.020 inches. The inside diameter (ID) of the cylindrical wall segment  655  not covered by the lip  656  is preferably 0.890 inches. The cap  614  is pressed onto the insert  612  and the cylindrical wall segment  655  undergoes plastic and elastic deformation. The resulting interference fit between the first cylindrical surface  641  and wall segment  655  is approximately 0.0025 inches.  
      In effect, both the wall segment  655  not covered by the lip  656  and the double thickness portion  657  of the wall segment  655 ,  656  including the lip, stretch radially outwardly as the cap  614  is pressed on to the insert  612 . When the lip  656  passes the shoulder  643 , it snaps radially inwardly due to the elastic component of the deformation, effectively locking the cap on the nut insert.  
      Referring now to  FIG. 21 , a variation of the seventh embodiment capped wheel nut assembly  610  is seen at  710 . The assembly  710  is very similar in construction and operation to the assembly  610 , so only differences are described. Reference numerals which correspond to those of the assembly plus  100  digits are employed.  
      In the assembly  710 , the circular cylindrical wall segment  755  of the cap  714  has an axially longer cylindrical lip  756 , and the shoulder  743  is located accordingly. No offset is formed in the wall segment  755  so the double thickness portion  757  is not centered under the remainder of the wall segment  755 .  
      The cylindrical surface  742  adjacent the shoulder  743  has an outside diameter of 0.890 inches. The inside diameter of the cylindrical lip  756  is 0.870 inches. When the cap  714  is press fit onto the insert  714 , the wall segment  755  and lip  756  undergo plastic and elastic deformation. An interference fit between the lip  756  and the surface  742  is approximately 0.0025 inches.  
      It should be pointed out at this point that the various inserts described might be plated first and then coated. They might also be plated in a conventional manner and not coated. The invention contemplates employing any of these approaches to protect a carbon steel insert from the elements. It should also be understood that although only the third embodiment assembly  210  ( FIGS. 10 and 11 ) illustrates using separate interference fits at two axially spaced, mating cylindrical surfaces, the invention contemplates the use of either one or two sets of mating cylindrical surfaces in any embodiment, as a matter of choice.  
      While preferred embodiments of the invention have been described, it should also be understood that the invention is not so limited and modifications may be made without departing from the invention. The scope of the invention is defined by the appended claims, and all devices that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein.