Abstract:
A method of securely attaching a plate to a malleable metal rod includes forming an integral, generally annular projection on one end of the rod. An opening through the plate is configured to receive the annual projection on the rod. The annual projection is inserted through the opening in the plate and is permanently deformed radially outwardly to overlie and contact the plate at a plurality of spaced locations. The deformations in the annular projection securely attach the plate to the rod.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to a method of securely attaching a plate, such as an anti-rotation plate or flag, to a metal rod, such as a bolt or stud.  
           [0002]    Anti-rotation retainers or flags are typically attached to a flange head bolt by staking the corners of the bolt head. Anti-rotation retainers or flags are used in many mass production applications, including automotive applications, to prevent rotation of a bolt during threading of a nut on the threaded end of the bolt using a power wrench. The bolt  20  typically includes a shank portion  22 , which may be threaded as shown in FIG. 1 at  24 . The bolt also includes an integral radial flange portion  26  and a polygonal head  28 . The anti-rotation retainer or flag  30  typically includes a polygonal opening  32  configured to receive the polygonal head  28  of the bolt and the corners of the bolt head are staked, forming small integral projections  34  which overlie the plate  30 . That is, the corners of the polygonal head  28  of the bolt are shaved from the free end  29  of the bolt toward the plate  30  and the small projections  34  retain the plate to the bolt.  
           [0003]    However, there has been a longstanding problem with this method of securement. The projections  34  are relatively fragile because only the portion of the projections adjacent the plate is integral with the bolt head  28 . These projections  34  often break during staking and during handling prior to and during assembly of the bolt in its final application, such as the assembly of a vehicle suspension control arm.  
           [0004]    As stated above, the purpose of the anti-rotation retainer or flag is to prevent rotation of the bolt during threading of a nut (not shown) on the bolt using a power wrench. The anti-rotation retainer or flag  30  serves as a wrench during assembly of a nut on the bolt. The flag  30  may include a bent tab  36  which is received between the components of the assembly or in a hole provided in one of the components to be assembled. Thus, the anti-rotation retainer or flag eliminates the requirement of someone holding the bolt with a wrench as a nut is threaded onto the threaded end  24  of the bolt.  
           [0005]    For this reason, bolts having an anti-rotation retainer are used extensively by many industries, including the automotive industry, to reduce labor costs during assembly.  
           [0006]    However, as stated above, the small staked projections  34  often break off and the anti-rotation retainers become loose or commonly fall off prior to and during assembly of the bolt in its final application. The bolt is then useless where an anti-rotation means is required and discarded. Thus, there has been a longstanding need for a method of securely attaching a plate, such as an anti-rotation retainer, to the head of a flanged bolt which eliminates the problems associated with external staking of the bolt head to the plate by the present method(s).  
         SUMMARY OF THE INVENTION  
         [0007]    The method of securely attaching a plate, such as an anti-rotation retainer or flag, to a rod, such as a conventional flange head bolt, of this invention eliminates the problems associated with conventional staking. The resultant rod and plate assembly of this invention is generally stronger than the plate. That is, the push-off force required to remove the plate from the bolt head is generally stronger than the plate, eliminating the problems associated with the prior art described above.  
           [0008]    The method of attaching a plate to a malleable metal rod of this invention includes forming an integral annular projection on the head of the rod or flange head bolt. The annular projection is preferably polygonal and most preferably includes a central recess surrounded by a polygonal annular wall. The method then includes forming an opening through the plate configured to receive the integral annular projection on the rod, inserting the annular projection of the rod through the opening in the plate, and permanently deforming the annular projection on the rod radially outwardly to overlie and preferably contact the plate at a plurality of spaced locations, permanently attaching the plate to the rod.  
           [0009]    In the most preferred embodiment of the method of attaching a plate to a rod of this invention, the method includes deforming the polygonal annular projection on the rod at the corners of the polygonal projection using a die member having a plurality of spaced radial projections which engage the internal surfaces of the corner portions of the polygonal annular wall radially outwardly to overlie and contact the plate forming a very secure assembly. In the most preferred method of this invention, the die member includes a plurality of spaced generally conical projections angling downwardly from the axis of the die member which deform an inside surface of the annular projection radially outwardly at an angle relative to the axis of the rod, forming a plurality of integral ribs which angle outwardly to overlie and preferably contact the plate.  
           [0010]    The rod and plate assembly of this invention therefore includes a rod having a radial flange portion, a head portion and an integral annular polygonal projection having polygonal side walls surrounding a central recess or pocket which extends from the flange portion, a plate having a polygonal opening therethrough which is received on the polygonal projection, and the integral polygonal projection is deformed radially outwardly to overlie and preferably contact the plate at a plurality of spaced locations, preferably at the corners of the polygonal projection. In the most preferred embodiment, the projections extend radially at an angle relative to the axis of the rod, most preferably at an acute angle.  
           [0011]    The method of securely attaching a plate to a metal rod and rod and plate assembly of this invention thus solves the problems associated with the prior method of staking described above, eliminating loss of anti-rotation retainers and thereby reducing cost. Further, the size of the bolt head may be reduced, reducing the weight of the assembly and cost. Finally, the plate and rod assembly of this invention reduces manufacturing cost as discussed further below. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 illustrates a prior art stud and anti-rotation retainer assembly;  
         [0013]    [0013]FIG. 2 illustrates a prior art die member and direction of travel into the prior art stud and anti-rotation retainer assembly;  
         [0014]    [0014]FIG. 3 illustrates the inventive die member and direction of travel into the stud and anti-rotation retainer assembly of the present invention; is a side view of a flange bolt of this invention with an anti-rotation retainer assembled on the bolt head;  
         [0015]    [0015]FIG. 4 is an end view of the flange bolt shown in FIG. 3;  
         [0016]    [0016]FIG. 5 is a side view of a flange bolt and retainer member of this invention prior to being formed by the method of this invention;  
         [0017]    [0017]FIG. 6 is a side view of a flange bolt and retainer member of this invention formed by the method of this invention;  
         [0018]    [0018]FIG. 7 is a top view of FIG. 6;  
         [0019]    [0019]FIG. 8 is a exploded view of the flange through section  8 - 8  in FIG. 7;  
         [0020]    [0020]FIG. 9 is a bottom view of the inventive die member;  
         [0021]    [0021]FIGS. 10 and 11 illustrate the movement of the inventive die member and the formation of the flange bolt; and  
         [0022]    [0022]FIG. 12 is a perspective view of alternative embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    [0023]FIGS. 3, 4, and  5  illustrate the rod and plate assembly of this invention prior to securement of the plate to the rod in the form of an anti-rotation stud similar to the anti-rotation stud shown in FIG. 1. As will be understood by those skilled in this art, however, the method of securing a plate to a rod of this invention may be utilized with any conventional rod, preferably including a flange, and any conventional flange head bolt to secure a plate to the rod, including the anti-rotation retainer or flag shown at  54 . Thus, the stud or bolt  40  shown in, FIGS.  3 ,  4 , and  5  includes a shank portion  42 , which may be threaded as shown at  44 , a radial flange portion  46  and an integral head portion  48 , which is preferably polygonal in this embodiment to prevent rotation of the anti-rotation retainer or flag  54  relative to the bolt  40 , however, as described below, other shapes may also be utilized. The S head further includes a recess or pocket  50  which, in the disclosed embodiment, is cylindrical, but may take other forms including a polygonal recess which is concentric with the polygonal external surface of the head portion  48 . The recess  50  in the end of the head portion  48  thus defines an annular wall  52  which projects from the head portion  48 .  
         [0024]    The anti-rotation retainer or flag  54  includes an opening  56  which is configured to receive the head portion  48  and is thus preferably hexagonal. As described above in regard to FIG. 1, the anti-rotation retainer  54  may take various forms depending upon the application. The method of this invention thus includes forming an annular integral projection or wall  52  on the end of the rod prior to installation of the anti-rotation retainer  54  and assembling the anti-rotation retainer  54  on the rod by inserting the annular projection  52  through the opening  56  in the end of the rod.  
         [0025]    [0025]FIGS. 6, 7, and  8  illustrate the bolt and plate assembly following securement of the plate to the bolt head. As best shown in FIG. 7, the annular projection  52  is deformed radially outwardly at  58  at spaced locations forming radial projections  60  which overlie the plate  54  and the portion adjacent the plate contacts the plate as shown in FIG. 8. In the most preferred embodiment shown in FIGS. 6, 7, and  8  and discussed further hereinbelow, the radial portions  60  extend at an acute angle relative to the axis “a” of the bolt, such that the malleable metal easily flows radially during deformation of the annular wall  52 . As will be understood, the annular wall or projection  52  can be deformed radially, rather than at an angle; however, the force required to deform the annular wall radially is significantly greater than the force required to deform the annular wall or projection at an angle as shown. It has also been found that in the most preferred embodiment of the bolt and plate assembly of this invention, the annular wall or projection  52  is deformed at the comer portions of the polygonal wall forming a more secure assembly.  
         [0026]    The resultant headed bolt and plate assembly shown in FIGS. 6 and 7 therefore solves the problems associated with the prior method of staking the outer comers of the polygonal head as shown in FIG. 1. First, the frangible staked comers  34  shown in FIG. 1 are eliminated, resulting in a much more robust assembly. Actual testing has indicated that the pull-off force required to remove the plate  54  from the bolt  40  is actually greater than the strength of the anti-rotation retainer in many applications. Therefore, the radial projections  60  are not subject to fracture and the anti-rotation retainer  54  therefore does not fall off the bolt. Further, the forming operation is less press sensitive, essentially eliminating scrap. Further, the length of the head portion  48  may be reduced as will be understood by comparing the length of the head portion  28  shown in FIG. 2 with the length of the head portion  48  shown in FIG. 3. This results in a reduction of the weight of the overall assembly, and less material usage which is very important in mass production and automotive applications. Further, because the axial length of the head is reduced, the stroke of the press deforming the annular projection is reduced, resulting in improved cycle time and reduced manufacturing costs.  
         [0027]    FIGS.  9 - 11  illustrate a suitable die member  62  which may be used to secure a plate, such as the anti-rotation retainer  60 , to the head portion  48  of the flange bolt  40  shown in FIGS. 2 and 3. The die member  62  is supported by a tool shaft  63 . The die member  62  includes a plurality of spaced angled die surfaces  64  which in combination define a cone of revolution. The central portion  66  is received in the recess or pocket  50  in the end of the head portion  48  and the die surfaces  64  are driven against the inside surface of the corner portions during radial deformation of the annular projection or wall  52  forming the radially deformed projection  60  shown in FIGS. 5 and 6 described above.  
         [0028]    FIGS.  10 - 11  illustrate the method of this invention, which includes forming an annular projection or wall  52  on the end of the headed bolt  40 . A plate, such as an anti-rotation retainer  54 , is then assembled on the bolt head portion  48  by inserting the annular projection  52  on the bolt head through an opening in the plate configured to receive the bolt head as shown in FIG. 10. In the preferred embodiment, the bolt head is polygonal, as described above, and the opening  56  through the plate  54  is also polygonal to prevent rotation of the plate on the bolt following assembly. The die member  62  is then located over the assembly in a die press (not shown). The die member or punch  62  is then driven toward the head portion  48  of the bolt as shown in FIG. 11, wherein the inclined die surfaces  64 , best shown in FIGS. 3 and 9, deform the corner portions of the annular wall or projection  52  as shown in FIG. 11 and FIGS. 6 and 7, described above. As best shown in FIG. 5, the resultant bolt and plate assembly is star-shaped in plan view as best shown in FIG. 5.  
         [0029]    Having described the preferred embodiments of the plate and rod assembly and method of forming this assembly of this invention, it will be understood that various modifications may be made within the purview of the appended claims. For example, FIG. 12 shows a further alternative die member  262  having an oval cross-section. The oval die member  262  is received by an oval wall  252  having a oval cross-section and is inserted in a oval aperture in the flag  154 . In alternative embodiments, the die member  162 ,  262  deforms the wall  152 ,  252  radially outward with the spaced angled die surfaces  64 .  
         [0030]    Although this invention has particular advantages in securing an anti-rotation retainer to a flange head bolt as disclosed in this application, the method and resultant plate and rod assembly may be used in many other applications as described above. Further, the metal selected for the bolt will depend upon the particular application. As will be understood, however, the bolt should be formed of a malleable metal, such as SAE 1020 to 1035 steel. Further, the depth of the recess or pocket  50  will depend upon the thickness of the retainer, plate, or flag. However, testing has indicated that a suitable depth for the recess  50  is between 0.020 and 0.030 inches or above the surface of the retainer, plate, or flag when it is located on the bolt head.