GB2345326A

GB2345326A - Plate and nut or bolt assembly

Info

Publication number: GB2345326A
Application number: GB9930201A
Authority: GB
Inventors: William F Hartery
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 1998-12-28
Filing date: 1999-12-21
Publication date: 2000-07-05
Anticipated expiration: 2019-12-21
Also published as: DE19954912C2; CA2287668A1; DE19954912A1; GB9930201D0; GB2345326B; JP2000230531A

Abstract

An assembly of a plate 22 and two bolts 30 is made by first forming an extruded collar 24 around each of two apertures in the plate, inserting the polygonal heads 32 of bolts through the apertures into the collars 24 to deform each collar to the shape of the head and then coining down the material of the bolt heads and/or the collars to retain the bolt heads in the apertures. Nuts may be retained in the apertures instead of bolts (Fig. 9). A stress-reducing rib 28 is formed in the plate between the apertures. The assembly may be used to secure a vehicle bumper to its frame.

Description

2345326 PLATE AND NUT OR BOLT ASSEMBLY The present invention relates to

the field of bolt assemblies used in automotive manufacture, for example, in the attachment of a vehicle bumper to a vehicle body or frame.

A known bolt assembly 300 used in the automotive industry is shown at FIG 10. This assembly comprises two bolts 302 with star shaped bolt heads 304 (as best seen in FIG. 11) which are molded into a plastic web 306 that holds the bolts 304 in roughly parallel positions a fixed distance apart. However, in practice, the bolt positioning is not consistent, there are deviations in product manufacturing that lead to bolt positioning which is inconsistent in the distance between the bolt centers, and the bolt orientation may not be true, e.g. the bolts may not be precisely perpendicular to the plastic web, due to either the slight resilience of the plastic web, and/or the manufacturing process. This known bolt assembly also has the disadvantage of cost. Although the plastic material is relatively inexpensive, the unusual star headed bolts, which are required to maintain a sufficiently high strength connection between the bolt and the web into which it is molded, are more expensive than conventional hexagonal head bolts. Typically, for a dual bolt assembly used in an automotive application such as affixing a vehicle bumper to a vehicle frame or body, there is a specified minimum strength requirement of 220 Newtons (about 50 lbf) pull- out force (e.g. the bolt should be retained in the plastic web at force levels up to at least 220 Newtons) and a minimum spin-out force of 75 N.m (about 55 ft-lbs.) (e.g., the bolt should not be caused to rotate by torque applied to the bolt at force levels up to at least S5 ft-lbs.) It would be desirable to provide a plate and bolt assembly for use in the automotive industry with a more consistent bolt positioning than in the known bolt 2 assembly. It would be desirable to provide a plate and bolt assembly that resists separation of the bolts from the assembly with a very high pull- out force. These objects are met by a plate and bolt assembly in accordance with one embodiment of the invention which comprises: a plate having two upwardly extruded collared apertures a fixed distance apart; and two bolts, having polygonal heads mounted within the collared apertures of the plate. The heads of the bolts are sized so that they deform the collars to a generally polygonal cross-sectional shape that conforms to the polygonal bolt heads. To enhance the secure mounting of the bolt heads in the collars, the corners of the polygonal bolt heads are coined down. Preferably, the polygonal bolt heads are hexagonal, and the bolts have integrally formed is flanges with their polygonal bolt heads. In addition, the plate preferably is formed from a pre-galvanized high strength low alloy sheet steel, having a thickness of between about 0.060 to about 0.080 inches (about 1.5 to 2.Omm), most preferably, of about 0.072 inches (about 1.8mm). The plate preferably also has a central stress relieving rib stamped between the collared apertures. The bolts are securely retained in the plate such that a pullout force of 2250 Newtons (505 lbs.) or more is required to separate the polygonal head of the bolt from the collared apertures of the plate; and a torque force of at least 88 Newton-meters (65 ft-lbs.) is required to rotate the hexagonal head of the bolt in the collared aperture of the plate.

In another embodiment of the invention, the apparatus is a plate and nut assembly, wherein two nuts are mounted into the plate in place of the bolt heads described above.

A method of manufacturing a plate and bolt assembly in accordance with the invention comprises a series of steps that begins with upwardly extruding a pair of circular collared apertures in a strip of sheet metal using a progressive die that, in steps, pierces the sheet metal in two positions a fixed distance apart, then forms extruded 3 collars by a punch together with a mating die that together act on the pierced sheet metal to form a finished pair of collared apertures a preselected fixed distance apart. A pair of hexagonal head bolts are then positioned a fixed distance apart in a tool, with the bolt shafts extending downwardly. The extruded collared apertures are pressed onto the hexagonal head bolts until the collars are deformed to a generally hexagonal shape matching the hexagonal heads of the bolts, thereby mounting the bolts to the sheet metal. The collars may extend up a portion of, or the entire height of, the bolt heads. A round die is then pressed over the bolt heads and/or the collars to coin the corners of the hexagonal heads of the bolts and/or the collars to mechanically fasten the metal together. A rib is then stamped in the sheet metal between the collars to relieve stress in the sheet metal. Finally, the sheet metal is sheared using a shaped blanking die to form a plate of a desired size and shape containing the collars, with the bolts mounted therein. 20 Particular embodiments in accordance with the present invention will now be described with reference to the accompanying drawings; in which:FIG. 1 is a perspective view of a plate and bolt assembly in accordance with one embodiment; FIG. 2 is a side elevation view showing, schematically, a manufacturing line with a series of stations for fabricating a plate and bolt assembly as shown in FIG. 1 from a strip of sheet metal; FIG. 3 is a perspective view showing a portion of a strip of sheet metal into which apertures have been pierced in an initial step of fabricating a plate and bolt assembly as shown in FIG. 1; 4 FIG. 4 is a perspective view showing a portion of a strip of sheet metal into which the pierced apertures formed in FIG. 3 have been worked with a progressive die to form extruded circular collars around the apertures, in a subsequent step of fabricating a plate and bolt assembly as shown in FIG. 1; FIG. 5 is a perspective view showing a placement of the hexagonal head of a bolt into one of the extruded circular collars formed in FIG. 4, in a subsequent step of fabricating a plate and bolt assembly as shown in FIG. 1; FIG. 6 is a perspective view showing the deformation of a circular collar into a generally hexagonal shape by the force of mounting a hexagonal bolt head into an extruded circular collar as shown in FIG. 5; FIG. 7 is a perspective view showing the results of coining the corners of the hexagonal bolt head and/or the generally hexagonally shaped collar containing the hexagonal bolt heads, to secure together the bolt head and the collar; FIG. 8 is a perspective view showing a rib located in the sheet metal between two bolts; FIG. 9 is a perspective view showing of a plate and nut assembly in accordance with another embodiment of the invention, where a nut is used instead of a bolt; FIG. 10 is a perspective view of a prior art plate and bolt assembly; and,

FIG. 11 is a perspective view of a bolt used in the prior art assembly.

Referring now to FIG, 1, a plate and bolt assembly 20 in accordance with an embodiment of the invention is shown.

Assembly 20 comprises a plate 22 formed from a sheet steel, the plate 22 having two extruded collars 24 extending upwardly from the plate 22. Plate 22 has a thickness of between about 0.060 to about 0.080 inches (about 1.5mm to 2.Omm), most preferably about 0.072 inches (about 1.8mm).

Collars 24 are a fixed distance apart from each other.

Collars 24 surround apertures 26 through the plate 22. A rib 28 is located between the collars 24. Two bolts 30 are mounted onto the collars 24, with one bolt 30 mounted into each of the collars 24. Each bolt has a polygonal head 32, an integral flange 34 and a threaded shaft 36. Preferably, the polygonal heads 32 are conventional hexagonal bolt is heads 38 (also referred to as "hex heads,'). The bolts 30 are mounted into the collars 24 by their hex heads 38. The hex heads 38 are inserted from the flat underside of the plate 22 upwardly through the apertures 26, so that the hex heads 38 are received into the upwardly extending collars 24 from below, and the bolt flanges 34 seat against the bottom of plate 22. The bolt shafts 36 extend downwardly.

The hex heads 38 deform the collars 24 to a generally hexagonal cross-sectional shape that conforms with the shape of the hex heads 38. The bolts are secured in position on the plate 22 by coining of one or more of (1) the corners 40 of the hexagonal heads of the bolts, and (2) the deformed corners 42 of collars 24. Coined corners 42 of the hex heads 38 are shown in FIG. 7. As can be seen in Fig. 1, where the height of the collars 24 is less than the height of the hex heads 38, the coining may be limited to the upper portions of the hex heads 38 extending upwardly above the collars 24.

In testing, it has been found that the plate and bolt assembly 20 requires a pull-out force of 2250 Newtons (505 lbs.) to separate the hex head 38 of the bolt 30 from a collar 24 of plate 22. It has also been found that a torque force of 88 Newton-meters (65 ft-lbs) or more is required 6 to rotate the hex head 38 of the)Do-t 30 in the collar 24 of plate 22.

FIG. 9 discloses a variation of the invention wherein a nut 52 is substituted for a bot -n the plate and nut assembly So. The plate and nut assembly 50 shown in FIG. 9 is useful in many of the same applica-Lons as the plate and bolt assembly 20.

The preferred method of manufacturing the plate and bolt assembly 20 is illustrated as a series of sequential steps in FIGS. 2-8. The steps are performed at a series of stations as illustrated in FIG. 2. The first step involves upwardly extruding pairs of circular collared apertures 24 in a strip of sheet metal 60 using a progressive die. As shown in FIG. 2, the strip of sheet metal 60 is wound in a large coil 62 and the strip is progressively unwound from the coil and fed through the die. The die 64 first pierces the sheet metal at station 66 to form apertures 26 which are a fixed distance apart, as illustrated in FIG. 3. The die then forms the extruded collars 24 at a station 68. The die uses a cylindrical punch, together with a mating hollow cylindrical die whose walls are spaced apart from the punch wails, which act on the pierced sheet metal to f orm a finished pair of collars 24 a preselected. fixed distance apart. The finished pair of collars 24 are illustrated in FIG. 4. A pair of bolts 30 having hexagonal heads 38 and shafts 36 are then positioned at station 70. The bolts 30 are positioned a fixed distance apart in a supporting tool, with the bolt shafts 36 extending downwardly, as shown in FIG. 5. The extruded collars 24 are then pressed onto the hexagonal heads 38 of bolts 30 until the extruded collars 24 are deformed to a generally hexagonal shape which matches the hexagonal heads 38 of the bolts 30, as shown in FIG. 6. At this stage in the method of manufacture, the bolts are mounted to the sheet metal strip 60. Corners 40 of the hexagonal heads of the bolts and/or the corners 44 of the collars are 24 then coined down using a round die, to securely hold the bolts 30 in place in sheet metal strip 7 60, at station 72. In essence, the round die deforms the corners 40 of the hexagonal heads 38 of the bolts 30 and extrudes the metal of the heads 38 until it combines with the metal of the collars 24. A rib 28 is then stamped into sheet metal 0 at station 74 between the collars 24 to relieve stress in the sheet metal strip 60. Finally, the finished piece 20 is sheared from the sheet metal strip 60 at station 76 using a shaped blanking die, to form a plate 22 of a desired size and shape with the bolts 30 mounted 10 therein.

Accordingly, the present invention provides a sturdy plate and bolt assembly which can be manufactured using standard hex head bolts, and which is very accurate in the positioning of its components. The plate and bolt assembly is can be rapidly manufactured using appropriate tooling.

8

Claims

1. A plate and bolt assembly, comprising:

a plate, having two extruded collared apertures extending upwardly from said plate a fixed distance apart from each other; two bolts, both having a polygonal head having corners and a shaft, one of said bolts being positioned with its head located within one of said collared aperture, the other of said bolts being positioned with its head located within the other of said collared apertures, both said bolts being positioned with their shafts extending parallel, said polygonal heads deforming said collars to a generally polygonal cross-sectional shape conforming to said polygonal heads and having corners; at least one corner of said polygonal heads or at least one corner of the said extruded collared apertures being coined down to retain said polygonal heads of said bolts in said extruded collared apertures. 20 2. A plate and bolt assembly according to claim 1, wherein said polygonal heads are hexagonal heads. 3. A plate and bolt assembly according to claim 1 or 2, wherein said bolts have integrally formed flanges with their polygonal heads. 25 4. A plate and nut assembly, comprising: a plate, having two extruded collars extending upwardly from said plate a fixed distance apart from each other, said collars defining apertures through said plate; two hexagonal nuts, one of said nuts being positioned within one of said collar, the other of said nuts being positioned within the other of said collars, said hexagonal nuts deforming said collars to a generally hexagonal crosssectional shape; the outer surfaces of at least one of said nuts and collars being coined down to retain said hexagonal nuts in said collars.

9 5. An assembly according to any one of the preceding claims, wherein said plate is provided with a central stress relieving rib extending between said collared apertures.

6. An assembly according to any one of the preceding claims, wherein said plate comprises a pre-galvanized high strength low alloy sheet steel.

7. A plate and bolt assembly, comprising:

a plate formed from a sheet steel, said plate having two extruded collars extending upwardly from said plate a fixed distance apart from each other, said collars defining apertures through said plate, and having a rib located between said collars; two bolts, both having a hexagonal head, an integral is flange and a threaded shaft, one of said bolts being positioned with its head located within one said collar, the other of said bolts being positioned with its head located within the other of said collars, both said bolts being positioned with their shafts extending parallel, said hexagonal heads deforming said collars to a generally hexagonal cross-sectional shape; corners of said hexagonal heads of said bolts being coined down to retain said hexagonal heads of said bolts in said collars. 25 8. An assembly according to any one of the preceding claims, wherein said plate has a thickness of between about 0.060 to about 0.080 inches (about 1.5 and 2.Omm) and preferably a thickness of about 0.072 inches (about 1.8mm). 9. An assembly according to any one of the preceding claims, wherein a pull-out force of 2250 Newtons or more is required to separate said polygonal head of said bolt or nut from said collared apertures of said plate.

10. An assembly according to any one of the preceding claims, wherein a torque force of 88 Newton-meters or more is required to rotate said hexagonal head of said bolt or said nut in said collar of said plate.

0 11. A method of manufacturing a plate and bolt assembly, comprising the steps of:

upwardly extruding a pair of circular collared apertures in a strip of sheet metal using a progressive die that, in steps, pierces the sheet metal in two positions a fixed distance apart, then forms the said extruded collars by a punch together with a die that acts on the pierced sheet metal to form a finished pair of collars a preselected fixed distance apart; positioning a pair of hexagonal head bolts having shafts in a tool, with said bolt shafts extending parallel, a fixed distance apart; pressing said extruded collars onto said hexagonal head bolts until said collars are deformed to a generally is hexagonal shape matching said hexagonal heads of said bolts, thereby mounting said bolts to said sheet metal; coining corners of said hexagonal heads of said bolts or said extruded collars, using a round die; stamping a rib in said sheet metal between said collars to relieve stress in the sheet metal; and, shearing the sheet metal using a shaped blanking die to form a plate of a desired size and shape containing said collars, with said bolts mounted therein.

12. An assembly substantially as described with reference to Figures 1 to 9 of the accompanying drawings