Securing device

Claim 1

A securing device to be inserted within holes defined within at least two plates to be secured together, comprising: an outer cylinder having a hollow cylindrical portion with a flange provided at one end, an inwardly projecting portion provided at the other end, a plurality of slits open at said other end and extending axially toward said flanged end so as to divide said hollow cylindrical portion into four quadrants with the outer surface of each quadrant comprising a flat surface disposed substantially perpendicular to the outer surface of each adjacent quadrant, and a plurality of axially spaced engagement ribs, each having the configuration of a trapezoid, projecting outwardly from each of said flat outer surfaces of said quadrants of said cylindrical portion such that the outermost edge surfaces of said trapezoidal ribs are disposed parallel to said flat surfaces of said quadrants of said cylindrical portion whereby each one of said outermost edge surfaces of said trapezoidal ribs are disposed substantially perpendicular with respect to adjacent outermost edge surfaces of said trapezoidal ribs so as to provide the ribbed portion of said outer cylinder with a first substantially square-shaped configuration; and an insertion member having a rod-like portion to be inserted into and movable within said outer cylinder, said rod-like portion having a head portion provided at one end, an intermediate large diameter portion having an outer diameter which is greater than the inner diameter of said inwardly projecting portion of said outer cylinder so as to be engaged by said inwardly projecting portion of said outer cylinder in order to radially expand said quadrant portions of said outer cylinder so as to cause said ribs to engage an inner peripheral surface of at least one of said holes of at least one of said plates to be secured together when said insertion member is disposed at a first axial position with respect to said outer cylinder, and a small diameter portion interposed between said large diameter portion and said head portion and having an outer diameter which is smaller than the inner diameter of said inwardly projecting portion of said outer cylinder so as to permit said securing device to achieve a released state with respect to said plates to be secured together when said insertion member is disposed at a second axial position with respect to said outer cylinder.