Helical spring fastener

Abstract

The invention is a two-ended fastener having one end suitable for attaching the fastener to a base with a second end having a special thread that is substantially cylindrical at its root and sharp at its crown. This thread is designed to mate with the radially inward surfaces of a round wire helical spring so that the helical spring may simply be threaded to the fastener. By utilizing the special thread described, a high degree of surface contact between the fastener and the spring is made possible, increasing spring retention. The special thread inner diameter may be made slightly larger than the interior diameter of the spring so that the helical spring will be slightly expanded when threaded to the fastener. An elastic force between the threaded portion of the spring and the fastener further helps retain the spring to the fastener. This elastic force increases as an attempt is made to unthread the spring from the fastener.

What is claimed is: 
     
       1. A fastener for retaining a round wire helical spring comprising: a first end for attaching said fastener to a base; and   a substantially cylindrical second end for attaching said fastener to said helical spring, said second end having an exterior thread that is cylindrical at its root and sharp at its crown and that substantially conforms to radially inward surfaces of said helical spring, said exterior thread further having an inner diameter that is slightly larger than an inner diameter of said round wire helical spring so that said helical spring is slightly expanded where threaded to said fastener.   
     
     
       2. An flexible link comprising: a round wire helical spring; and   a fastener attached at both ends of said round wire helical spring, each of said fasteners having an exterior thread substantially cylindrical at its root and sharp at its crown that mates with radially inward surfaces of said round wire helical spring, with said exterior thread further having an inner diameter that is slightly larger than an inner diameter of said helical spring so that said helical spring is slightly expanded where threaded to said fasteners.   
     
     
       3. An antenna system comprising: a round wire helical spring having a first and second end;   a fastener having a first end for attaching said fastener to a base and having a second end for attaching said fastener to said first end of said round wire helical antenna spring, said second end of said fastener having an exterior thread substantially cylindrical at its root and sharp at its crown that mates with radially inward surfaces of said round wire helical spring;   an antenna whip;   a collar having a recess into which an end of said antenna whip is fixed;   a second fastener having a first end for attaching to said collar and having a second end for attaching to said second end of said round wire helical antenna spring, said second end of said second fastener having an exterior thread substantially cylindrical at its root and sharp at its crown that mates with radially inward surfaces of said round wire helical spring, and in which said exterior thread of said fasteners have an inner diameter that is slightly larger than an inner diameter of said helical spring so that said helical spring is slightly expanded where threaded to said fasteners.