Method of removing broken threaded fasteners
OwnerOrlin J. Feeninventor
Life of this patent
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Abstract
A method for removing broken fasteners so as to render the broken shank readily removable from a tapped hole in a machine part after a shear-type fracture of the fastener shank. In one illustrated form the fastener is a hexhead machine bolt having uniformly spaced slots cut into the shank from one end thereof to the other and filled with a lubricant material prior to installation. After a shear-type fracture a tool having axial projections at one end thereof mating with the slots is inserted into the interstices formed by the slots in the periphery of the sheared-off shank portion to force lubricant into the threads and to provide reaction surfaces to enable use of the tool to turn the shank portion out of the tapped hole. A second illustrated embodiment of the fastener shows an Allen head stud similarly slotted.
Claims2
A method of removing the broken shank portion of an externally threaded fastener of the type having a head portion adapted to provide a drive surface for installation of said shank portion into a mating threaded bore, the method comprising the steps of:
- forming a plurality of circumferentially spaced slots along the length of said shank, said slots being formed into the threaded portion of said shank fastener prior to installation thereof in said mating threaded bore;
- filling the slots with a lubricant material;
- forcing the lubricant material in each slot into the surrounding threads by inserting a tool having projections complementarily shaped to the slots into the slots;
- rotating said shank portion out of said bore by means of said tool, by engagement with said circumferentially spaced slots, whereby any portion of said fastener shank may be removed along which said circumferentially spaced grooves extend.
Dependencies are inferred from the claim text.