Patent Publication Number: US-2004047705-A1

Title: Cage-nut assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     [0001] This application is a division of U.S. application Ser. No. 09/626,610, filed Jul. 27, 2000, which, in turn, claims the benefit of U.S. provisional application Serial No. 60/175,593, filed Jan. 11, 2000. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates to caged female threaded fasteners which provide high torsional strength while allowing removal of the fasteners for servicing.  
       [0004] 2. Background Art  
       [0005] It is a common manufacturing practice to apply coatings of paint or other decorative or protective coatings to large subassemblies prior to final assembly of the completed product. For example, in the manufacture of automobiles, the body of the automobile will be formed and assembled, and then painted. Other automotive subassemblies, such as suspension parts, undercarriages, or closures for the automobile (such as the doors, hood, and trunk lid) are separately manufactured and painted, and are assembled with the painted automobile body to form a complete automobile.  
       [0006] In most cases, the subassemblies of the automobile will be secured to the auto body by threaded fasteners. However, the use of threaded fasteners often presents difficulties in final assembly. For example, in the case of assembling a door into a body, one of the matching threaded fasteners, for example, a female fastener, may be located inside a door pillar. The door pillar in a modern automobile of unibody construction very often is a hollow metal part which may be completely enclosed after manufacture of the vehicle body. In order to provide a female fastener inside the pillar, it is necessary to mount the female fastener, for example by welding, inside the pillar when the body is being manufactured.  
       [0007] Due to variations in manufacturing tolerances, a degree of position adjustment for the female fastener must be provided so that the door and body may be properly aligned during final assembly. Position adjustment is provided by using a female fastener called a “cage-nut”, which is usually a nut encaged in a structure that is attached to the inside of the door pillar. The nut is provided with a range of movement within the encaging structure so that when the door is assembled to the body, the alignment of the door and the body can be adjusted until they meet manufacturing standards.  
       [0008] Cage-nuts are also frequently used in situations where the nut is not completely enclosed, such as on the frame of the vehicle. In these situations, the use of a cage-nut welded onto the body prior to final assembly reduces the time needed for final assembly of the automobile.  
       [0009] It has been found, however, that during the step of painting and baking paint on the body of the auto, that the nut will often weld or adhere to the cage. This paint-welding creates problems in the step of assembling and aligning the door or other subassembly within the body, because the nut no longer has any freedom of movement. It can be difficult to free the paint welded nut from the cage if it is in an enclosed space. Consequently, the final assembly of the automobile will be slowed while these parts are freed up enough so that the door or other subassembly can be properly aligned and assembled with the body.  
       [0010] Another problem associated with such cage-nut assemblies is that a bolt may be stripped or cross-threaded into the encaged nut, particularly if the nut is misaligned as a result of adhering to the cage structure. In this situation, it is difficult, if not impossible, to remove the nut and bolt for servicing because the nut may not be removable from the cage. Accordingly, it is desirable to provide an improved cage-nut design in which the frequency of paint-welding the nut to the cage structure is minimized, and the nut is removable from the cage for servicing when the bolt or nut are stripped or cross-threaded.  
       SUMMARY OF THE INVENTION  
       [0011] The present invention overcomes the above referenced shortcomings of prior art cage-nut assemblies by providing a cage-nut assembly including a Teflon-coated nut and a cage structure which provides high torsional strength while providing a structurally weak portion which allows bending of the cage structure for removal of the nut for servicing.  
       [0012] In a first embodiment, a flat base is provided with opposing strap portions which wrap around opposing ends of an oblong (i.e., longer than wide, including diamond shape or other shape providing a portion for containment and torsional resistance), Teflon-coated nut. The flat base forms an enclosed aperture for receiving a bolt. The straps are bendable away from the body to facilitate nut removal. The straps are configured to provide high torsional strength. Small tabs extend from the base to space the nut away from the base to prevent paint-welding of the nut to the base, and are bendable to allow the nut member to seat when torqued down.  
       [0013] In another embodiment, standoff legs support a flat base with an enclosed aperture formed therethrough for receiving a bolt. A rectangular Teflon-coated nut is positioned within the cage. The legs include small, bendable tabs which hold the nut in position and are bendable to allow the nut member to seat when torqued down (when a bending-force of approximately 65 lbs. is applied to the legs). One of the tabs prevents the nut from sliding out of the cage, and is bendable to allow removal and servicing of the nut (when a bending-force of approximately 10 to 20 lbs. is applied).  
       [0014] In a further embodiment, the cage-nut assembly includes a nut positioned within a cage structure, the cage structure being configured to provide high torsional strength to prevent rotation of the nut. Preferably, the cage structure provides sufficiently high torsional strength that the first failure would be that of the weld holding the cage structure against a workpiece when a significant torque is applied to the nut (preferably at approximately 190 Nm). The cage structure has a flat base and an at least partially open end portion. The cage structure includes a relatively structurally weak blocking member preventing the nut from exiting the cage structure through the end portion. The structurally weak blocking member is bendable when less than approximately 20 lbs. of force is applied to the blocking member to open the end portion and allow the nut to move laterally along the base through the end portion for removal of the nut. The flat base includes a bolt-receiving aperture which is formed coextensively with the at least partially open end portion. The blocking member comprises first and second curved tangs formed coplanar with the flat base. The nut includes a protruding tubular portion which extends through the bolt-receiving aperture. Standoff legs support the flat base and include small projections to facilitate projection welding.  
       [0015] In the various embodiments, the flat base may be positioned flat against a workpiece to which the nut is being attached, or may be spaced from the workpiece by the above-described standoff legs.  
       [0016] Accordingly, an object of the invention is to provide an improved cage-nut assembly in which the nut is removable from the cage for servicing.  
       [0017] The above object and other objects, features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0018]FIG. 1 shows a perspective view of a cage structure in accordance with a first embodiment of the invention;  
     [0019]FIG. 2 shows a plan view of the cage structure of FIG. 1;  
     [0020]FIG. 3 shows a side view of the cage structure of FIG. 2;  
     [0021]FIG. 4 shows a cross-sectional view taken at line A-A of FIG. 2;  
     [0022]FIG. 5 shows a plan view of a nut for use with the embodiment of FIG. 1;  
     [0023]FIG. 6 shows a side view of the nut of FIG. 5;  
     [0024]FIG. 7 shows a reverse side view of the nut of FIG. 5;  
     [0025]FIG. 8 shows a perspective view of a cage-nut assembly in accordance with the embodiment of FIG. 1;  
     [0026]FIG. 9 shows a perspective view of a cage-nut assembly in a slightly modified embodiment;  
     [0027]FIG. 10 shows the cage-nut assembly of FIG. 9 with the nut being removed from the cage structure;  
     [0028]FIG. 11 shows an underside perspective view of a cage-nut assembly in accordance with an alternative embodiment of the invention;  
     [0029]FIG. 12 shows a top perspective view of the cage-nut assembly of FIG. 11;  
     [0030]FIG. 13 shows a top plan view of the cage-nut assembly of FIG. 11;  
     [0031]FIG. 14 shows a side view of the cage-nut assembly of FIG. 13 with the bolt and vehicle body component;  
     [0032]FIG. 15 a  shows a cross-sectional view taken at line  15   a - 15   a  of FIG. 14;  
     [0033]FIG. 15 b  shows a cross-sectional view of the cage-nut assembly of FIG. 15 a , with the bolt torqued down and the nut seated;  
     [0034]FIG. 16 shows an enlarged view of detail  16  from FIG. 14;  
     [0035]FIG. 17 shows a plan view of the nut shown in FIG. 11;  
     [0036]FIG. 18 shows a side view of the nut of FIG. 17;  
     [0037]FIG. 19 shows a perspective view of a cage-nut assembly in accordance with a third embodiment of the invention;  
     [0038]FIG. 20 shows a plan view of a nut corresponding with the embodiment of FIG. 19;  
     [0039]FIG. 21 shows a sectional view taken at line  21 - 21  of FIG. 20;  
     [0040]FIG. 22 shows a plan view of a slightly modified embodiment of a cage structure in accordance with the invention;  
     [0041]FIG. 23 shows a side view of the cage structure of FIG. 22; and  
     [0042]FIG. 24 shows an end view of the cage structure of FIG. 22.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)  
     [0043] Referring to FIGS.  1 - 8 , a first embodiment of a cage-nut assembly  10  is shown in accordance with the present invention. The cage-nut assembly  10  includes a cage structure  12 , shown in FIGS.  1 - 4 , and a Teflon-coated nut  14 , shown in FIGS.  5 - 7 , which cooperate to form the cage-nut assembly  10 , shown in FIG. 8.  
     [0044] The cage structure  12  includes a flat base  16  having a fully enclosed aperture  18  formed therethrough for receiving a bolt (not shown). Standoff tabs  20 , 22  are angled slightly upwardly with respect to the flat base  16  to hold the nut  14  away from the base  16  to prevent the nut from paint-welding to the base  16  (i.e. sticking to the base by dried paint). The tabs  20 , 22  are bendable to allow the nut to seat when torqued down.  
     [0045] The base  16  is preferably a stamped steel component, and includes integral straps  24 , 26 , which form openings  28 , 30 , respectively, for receiving opposing ends  32 , 34  of the oblong nut  14 . The straps  24 , 26  are preferably stamped with the base  16  to form the openings  28 , 30 .  
     [0046] As shown in FIGS.  5 - 6 , the nut  14  is generally diamond-shaped and includes a central aperture  36  which is threaded to receive the bolt.  
     [0047] As viewed in FIG. 8, the flat base  16  would be welded to a vehicle frame or other structural component, and the bolt would be inserted through an underside thereof, as viewed in this Figure. The openings  28 , 30  in the straps  24 , 26 , respectively, are larger than the respective opposing ends  32 , 34  of the nut  14 , thereby allowing the nut  14  to float for alignment with the bolt. The engagement of the opposing ends  32 , 34  of the nut  14  with the straps  24 , 26 , respectively, provides very high torsional strength against rotation of the nut  14  during assembly.  
     [0048] The opposing ends  38 , 40  of the flat base  12  may be bent upward for servicing the nut  14 . As the opposing ends  38 , 40  are pried upward, the flat base  12  would bend in the structurally weakest areas  42 , 44 . In other words, the opposing ends  38 , 40  of the cage structure  12  are partially open, and the straps  24 , 26  are operative as blocking members which prevent the nut  14  from sliding through the partially open opposing ends  38 , 40 . The blocking members are relatively structurally weak in a direction orthogonal to the torsional rotation direction of the nut, such that the blocking members may be pried up to allow the nut to slide through one of the opposing ends  38 , 40 . The language “orthogonal to the torsional rotation direction of the nut” is intended to mean perpendicular to an arc swept out by a distal end of the rotating nut, and includes perpendicular directions which are in the plane of the arc or perpendicular to the plane of the arc.  
     [0049]FIGS. 9 and 10 show a slightly modified embodiment, wherein the opposing ends  38 ′, 40 ′ are substantially enclosed. The ends  38 ′, 40 ′ are only open at an underside thereof, as viewed in FIGS. 9 and 10. FIG. 10 illustrates the end  40 ′ having been pried upward with respect to the flat base  12  about the structurally weak portion  44  for removal of the nut  14  for servicing.  
     [0050] Referring to FIGS.  11 - 18 , a further embodiment of the invention is shown. These figures show a cage-nut assembly  60 , including the cage structure  62 , which is preferably a stamped steel component, and a Teflon-coated rectangular nut  64 .  
     [0051] The cage structure  62  includes standoff legs  66 , 68 , 70 , 72 , 74  which are welded to the vehicle body component  75  by the conical projections  76 , 78 , 80 , such as by projection welding or resistance welding.  
     [0052] The standoff legs  66 , 68 , 70 , 72 , 74  support a flat base  82  which has an enclosed aperture  84  formed therethrough for receiving the bolt  85  which is inserted from the vehicle body side of the cage structure  62 , as shown in FIGS. 14, 15 a  and  15   b , and protrudes through the lip  86  surrounding the threaded aperture  88  of the nut  64 . The lip  86  also protrudes through the enclosed aperture  84  of the base  82 , as shown in FIGS. 12 and 15 a.    
     [0053] This cage structure  62  in combination with the rectangular nut  64  provides substantial torsional strength for supporting the nut  64  against rotation when a bolt is driven into the nut  64  (preferably the weld fails before the cage structure at around 190 Nm). Between the legs  66 , 68 , 70 , 72 , 74 , vertical retainer tabs  90 , 92 , 94 , 96  are provided for holding the nut  64  against the base  82 .  
     [0054] The cage structure  62  is open at the longitudinal end between legs  66 , 68  such that movement of the bolt  64  therethrough is prevented only by the lateral retention tab  100 . Accordingly, if a bolt is cross-threaded into the nut  64 , the tabs  90 , 92 , 94 , 96  may be bent downward simply by pulling the nut  64  away from the base  82  by pulling on the bolt. This movement will bend the retainer tabs  90 , 92 , 94 , 96  out of the way for downward movement of the nut  64  so that the lip  86  does not interfere with the aperture  84  as the nut  64  is slid through the opening between the legs  66 , 68 . In order to slide the nut  64  through the opening between the legs  66 , 68 , the lateral retention tab  100  is pried upward to a position substantially parallel to the base  82 . A bending force of about 10-20 lbs. is required to bend the retention tab  100 . Accordingly, the nut  64  may be removed for servicing simply by bending the tabs  90 , 92 , 94 , 96  to move the nut  64  away from the base  82 , and then bending the lateral retention tab  100  upward to slide the nut  64  along the base out the end of the cage structure  62  between the legs  66 , 68 .  
     [0055] FIGS.  19 - 21  illustrate a third embodiment of the invention. In this embodiment, the cage-nut assembly  110  includes a cage structure  112  and a Teflon-coated nut  114 , which cooperate to form the cage-nut assembly  110 . The cage structure includes a flat base  116  which is supported by standoff legs  118 , 120 , 122 , 124 . The flat base  116  and the standoff legs  118 , 120  cooperate to form an open end  126 .  
     [0056] The standoff legs include bendable retainer tabs  128 , 130  which are configured to hold the nut  114  in position to be torqued down by a bolt. The tabs  128 , 130  are bendable to allow the nut  114  to move downward as viewed in FIG. 19 when torqued down to a workpiece by such a bolt. The tabs  128 , 130  are bendable under approximately 65-80 lbs. of bending torque. Of course, the tabs  128 , 130  could be configured in any variety of shapes, and the standoff legs could be combined to form a continuous support wall.  
     [0057] The flat base  116  includes a bolt-receiving aperture  132 , which is formed coextensively with the open end  126  of the cage structure  112 . The bolt-receiving aperture  132  receives a tubular extrusion  134  which extends from the nut  114 . The aperture  135  of the tubular extrusion  134  receives a bolt, not shown, which torques down the nut  114 .  
     [0058] First and second curved tangs  136 , 138  cooperate to form a blocking member which prevents the nut  114  from sliding along the flat base  116  through the open end  126  of the cage structure  112 . The tangs  136 , 138  are bendable toward the angled sides  140 , 142 , such as by a screwdriver, to allow the tubular extrusion  134  to pass by the blocking member formed by the curved tangs  136 , 138 , thereby allowing removal of the nut.  
     [0059] This blocking member, like other embodiments of the invention, is configured to allow removal of the nut for servicing. Like other embodiments, the curved tangs  136 , 138  are bendable when less than approximately 20 lbs. of force is applied to the curved tangs  136 , 138 , such as by a screwdriver, and the nut  114  may then be slid along the flat base  116  through the open end  126  of the cage structure  112 .  
     [0060] The standoff legs  118 , 120  include small projections  144 , 146  to facilitate projection welding of the cage structure  112  to a workpiece to which the nut  114  is being attached.  
     [0061] FIGS.  22 - 24  show a slightly modified embodiment of a cage structure in accordance with the invention, wherein like reference numerals with a prime (′) indicate like components from the embodiment of FIG. 19. This embodiment differs from that of FIG. 19 only in the number of bendable retainer tabs  128 ′. Of course, the number of retainer tabs and the number and configuration of the standoff legs could vary within the scope of the present invention.  
     [0062] While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention without departing from the scope of the appended claims.