US 3,978,760 AGranted

Self-thread forming threaded fasteners and blanks for making same

AssigneeResearch Engineering & Manufacturing, Inc.

InventorHerman M. Muenchinger

Life of this patent

Estimating the term…

Loading patent…

Abstract

A self-thread forming threaded fastener has a straight thread on a shank of circular cross section and a tapered thread on the work-entering end. The tapered portion of the thread is of lobular root, pitch and crest surface cross sections and which lobular configuration is continued, but to a diminishing extent, on the first few threads on the shank immediately adjacent to the tapered section. The fastener is formed by rolling between thread-rolling dies a blank having a cylindrical shank of circular cross section and an end section of arcuate lobular cross section including a tapered portion. At least the lobular and tapered portions of the blank are intermittently deflected first in one direction and then in the opposite direction by the dies. Due to such deflections of the end of the blank, a lobular tapered thread is produced on the tapered portion of the blank.

Claims7

Dependent claims

A thread-forming screw fastener comprising a threaded shank portion, a tapered thread-forming portion, and a lead portion, said thread-forming portion being intermediate the shank portion and the lead portion, the shank portion and the lead portion being cylindrical, the diameter of the lead portion being less than the diameter of the shank portion, the thread-forming portion diverging from the lead portion in a substantially conical configuration, the axis of a cone circumscribing the thread-forming portion being offset from and parallel with the axis of the lead portion whereby the thread-forming portion and the lead portion are eccentric relative to one another to provide a lobe on a portion of the periphery of the thread-forming portion, a thread-forming portion and the lead portion intersecting along a line which extends at an acute angle with respect to the axis of the lead portion whereby all planes transverse to the axis of the lead portion and extending through said line intersect both the lead portion and the thread-forming portion, the thread-forming portion having a partially formed thread with a substantially fully developed crest on the lobe, the thread on the thread-forming portion being a continuation of the thread on the shank portion.

Dependencies are inferred from the claim text.

Facts

Application: 05/432,957Filed 14 Jan 1974 · continuation in part
Priority: 19 Jan 1970
Granted: 7 Sep 1976
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

B21H 3/027
External screw-threads ; Making dies for thread rolling: rolling of self-tapping screws
F16B 25/0078
Characterised by geometric details of the screw: with a shaft of non-circular cross-section or other special geometric features of the shaft
F16B 25/0084
Characterised by geometric details of the screw: characterised by geometric details of the tip
Y10S 411/03
Expanded, threaded, driven, headed, tool-deformed, or locked-threaded fastener: utilizing fluid pressure

Family

Serial3,985Parent of this continuation-in-part · filed 19 Jan 1970
Serial253,974Parent of this continuation-in-part · filed 17 May 1972
3681963Parent of this continuation-in-part
3803889Parent of this continuation-in-part
US 3,978,760 AThis patent

From the US filing history. Foreign family members aren’t listed.