Method of making a multigrip fastener and fastener made thereby
AssigneeHuck Manufacturing Company
InventorLarry D. Mercer
Life of this patent
Estimating the term…
Abstract
This disclosure relates to swage type fasteners including a pin having a plurality of combination locking and breakneck grooves and a collar adapted to be swaged into the grooves with one of the grooves acting as a breakneck whereby the excess length of pin is severed generally at the end of the collar and also relates to a method of making the pin. The multigrip pin is formed generally into its final shape and then is subject to a heat treating process to provide a desirable microstructure whereby more consistent breaks at the selected groove occurs. In one form of the invention a desirable microstructure consists of predominantly pearlite colonies with a proeutectoid ferrite matrix interspersed at the boundaries of pearlite colonies.
Claims16
In a swage-type fastener including a pin and a collar adapted to be swaged onto said pin, the method of making said pin wherein said pin includes a plurality of combination locking and breakneck grooves and with said collar adapted to be swaged into said grooves with one of said grooves acting as a breakneck whereby excess length of said pin is severed at that one of said grooves generally at the end of said collar and in response to a relative axial force applied between said pin and said collar, said method comprising:
- (a) forming a steel billet,
- (b) hot rolling said billet into a rod,
- (c) sizing said rod to the desired diameter,
- (d) cutting blanks of desired length from said sized rod and forming an enlarged pin head on said cut blanks,
- (e) rolling said cut blanks to form a pin having combination locking and breakneck grooves thereon,
- (f) normalizing said pin at a preselected temperature in a carbon restoring atmosphere to austenitize and carbon restore the steel, and
- (g) cooling said pin from its austenitized state to form a generally homogeneous microstructure comprised predominantly of coarse grained pearlite colonies in a fine matrix of proeutectoid ferrite, said pearlite colonies having an apparent austenetic grain size of from about ASTM 1 to about ASTM 5, whereby fracture at said one of said grooves is facilitated.
In a swage-type fastener including a pin having a plurality of combination locking and breakneck grooves and collar adapted to be swaged into said grooves with one of said grooves acting as a breakneck whereby excess length of said pin is severed at that one of said grooves generally at the end of said collar and in response to a relative axial force applied between said pin and said collar, said pin having a generally homogenous microstructure comprised predominantly of coarse grained pearlite colonies in a fine matrix of proeutectoid ferrite, said pearlite colonies having an apparent austenitic grain size of from about ASTM 1 to about ASTM 5, whereby fracture at said one of said grooves is facilitated, said pin made by the process comprising:
- (a) forming a steel billet,
- (b) hot rolling said billet into a rod,
- (c) sizing said rod to the desired diameter,
- (d) cutting blanks of desired length from said sized rod and forming an enlarged pin head on said cut blanks,
- (e) rolling said cut blanks to form said pin having combination locking and breakneck grooves thereon,
- (f) heating said pin to an austenitizing temperature in a carbon restoring atmosphere, and
- (g) cooling said pin from the austenitizing temperature to form said generally homogenous microstructure.
Dependencies are inferred from the claim text.