Securing devices
AssigneeMulticlip Company Limited
InventorReginald F. Morton
Life of this patent
Estimating the term…
Abstract
A spiral member for improving the grip of screws in wooden or other receptive substrates is disclosed. The spiral member has a central axial drive pin by which it can be driven into a thread in the receptive substrate, and it has an improved cross section providing wings or protuberances extending out past the side surfaces of the cross section. The spiral member also has an outwardly facing triangular apex which bites into the old thread while the wings bear upon the flanks of the screw thread of the screw that inserted into the spiral member, thereby improving the grip.
Claims13
A spiral member for increasing the resistance to pull-out of a screw made of hard material received in a hole in a body of screw-receiving material which is of softer material than the screw, the spiral member being cylindrical or being tapered towards one end and being turned inwardly at one end or at its narrow end when it is tapered to afford a drive pin adapted to be engaged by an insertion tool insertable down the inside of the spiral member so that the spiral member can be screwed into the hole from its bottom end, characterised in that the spiral member is made of material whose hardness is less than that of the screw and greater than the hardness of the screw receiving material and in that the cross-section of the spiral member is generally triangular in shape, having a base surface which faces the axis of the spiral member and side surfaces which face outwardly from the axis and join at an apex, which may be sharp or somewhat blunted or rounded, the base surface being curved and extending out in wings or protuberances beyond the side surfaces, the side surfaces being straight or curved and the wings being rounded.
Dependencies are inferred from the claim text.