DEVICE FOR FASTENING OF SCREW, WAY OF SCREW FIXING IN THREADED HOLE AND TOOL FOR DRIVING SPIRAL MEMBER INTO THREADED HOLE OF LOCATION PART

摘要

A method of increasing the resistance to pull out of a screw (20) screwed into a receptive substrate (35) which comprises unscrewing the screw and removing it from the hole and then locating a spiral member (140) having an outwardly facing pointed profile and having a cross section such as to fit between adjacent turns of the thread on the screw, and such that the dimension of a turn perpendicular to the longitudinal axis of the spiral (herein called the radial depth) is greater than the height of the thread of the screw with which that turn will be associated, in the threaded hole and screwing the screw into the hole, the spiral member engaging the hole and the screw threadly engaging the spiral member and forcing the pointed profile into the substrate. The spiral member is preferably of intermediately malleable material e.g. an aluminium alloy. The bottom end (146 or 182) of the spiral member is shaped so as to be disconnectably engageable by a tool (50 or 160). Application in the field of screw-in rail spikes in wooden sleepers.