The variety of fasteners which have been developed for both general and specialized purposes is so vast as to defy ready description. The various types of nut and bolt assemblies, screws, rivets, nails, staples, etc. have long been used, for example, to: (1) fasten two objects together; (2) support or mount one object to another, including an object to a support surface; or (3) to extend through a support in order to retain the support together or otherwise strengthen the support. While the present invention generally relates to fasteners, the present invention specifically concerns blind-end fasteners.
When attempting to secure objects to supports, a person quite often encounters circumstances that afford physical access to only one side of a support. Where there is a desire to fasten or otherwise mount an object to the support, it is necessary to utilize a fastening device which only requires operative access at one end. Such devices may be referred as to blind-end fasteners since the securing of these fasteners may be accomplished on only that side of the support to which physical access is provided.
One type of blind-end fastener which is particularly related to the present invention are those devices known as anchor bolts which are adapted to fasten between opposite sides of a support through a bore or other opening formed therein. Such devices are often used in walls and ceilings of homes or other buildings and are adapted to fasten to wallboard, press board, peg board and the like. A fairly universal problem with these anchor bolts, though, is that they each typically require a bore or opening that is larger in size than the cross-sectional dimension of the bolt itself. By having an oversized opening, it is not unusual that the fastener becomes misaligned with respect to the axis of the opening. Furthermore, oversized openings in some instances reduce the structural integrity of the support and, should the fastener device be removed, the enlarged opening may require substantial cosmetic repair. Many of the existing anchor bolts are fairly complex in structure and thus expensive to produce and maybe difficult to install. Where expandable base anchors are used or where toggle type anchor bolts are employed, they each must be spaced a minimum distance from internal structures (such as vertical wall studs and horizontal braces between the studs) on the opposite or blind side of the support. This spacing is necessary to accommodate the expansion of the base or the physical dimension of the toggle nut employed by these fasteners. Another disadvantage of existing anchor bolts is the inability of many constructions to fasten onto thin wall supports. This is due to the physical dimension needed to allow the blind-end structure to operate after passage through the support. Further, there is a need for substantial interior space clearance after the base or the toggle nut expands due to the length of threaded penetration of the anchor bolt therethrough when the bold is tightened onto the support.
As a result of the disadvantages of previous anchor bolts, there have been attempts to improve anchor bolt constructions so as to reduce the relative size of the opening through which they must be inserted as well as to eliminate the problems of enlarged toggle nuts or expanding bases. One such example is found in U.S. Pat. No. 4,657,461 issued 14 Apr. 1987 to Smith. Here, a bolt and collet assembly is provided with the bolt adapted to extend through a support to the blind-side thereof while the collet is adapted to fasten onto the bolt to mount it within an opening in the support. The bolt is constructed as an elongated shaft having ridged teeth, threads or other fastening means on its exterior surface and the collet has interior structure to cooperatively engage the exterior ridged teeth or threads on the bolt. At the interior end or blind-end, the bolt is provided with a pair of arms connected to the end of the bolt with a goose-neck structure so that the arms are biased transversely of the bolt in the operative position but may be bent alongside the bolt when being inserted through the opening. Nonetheless, the teachings of this patent indicate that an opening substantially larger than the bolt cross-sectional dimension is still necessary to allow insertion of the bolt.
U.S. Pat. No. 4,439,079 issued 27 Mar. 1984 to Losada similarly discloses a pivoting cross-piece structure at the end of an anchor bolt. Here, however, the anchor bolt is formed by a pair of legs which may be bent with respect to one another thereby allowing pivoting of the cross-piece in a generally longitudinal direction. The cross-piece is in the form of a hinged, flat plate which will be oriented normally to the longitudinal axis of the bolt after insertion by the reorientation of the leg members. This device allows for insertion through an opening that is dimensioned substantially equal to the distance between the two bolt legs.
While not being directed to anchor-type bolts, U.S. Pat. No. 2,061,478 issued 17 Nov. 1936 to Pippin discloses a fastener in the form of a locking pin that has a pivotal cross-piece at the blind-end thereof. This cross-piece has a weighted arm which nests in a recess formed in the bolt shaft so that the locking pin maybe passed through an opening that is dimensioned substantially the same size as the cross-section of the bolt shaft. However, this locking pin relies upon the force of gravity allowing it to pivot about an axis formed by a U-shaped extension of the bolt. While this structure does allow for blind-side fastening, it can only be used in proper orientation, usually vertically, with respect to a gravitational field and therefore would have limited utility, if at all, as an anchor bolt.
Accordingly, there remains a need for improved fasteners of the anchor bolt-type which can mount between opposite sides of the support through an opening formed therein where access is accorded to only one side of the support. There is a distinct need for such fasteners that can pass through openings that are dimensioned of an approximate equal size to the dimension of the fastener itself, and there is a need for such fasteners that can be used despite the existence of internal structure on the blind-side of the support. There is a further need for fasteners which may be fastened to thin supports (as defined by the distance between its two sides).