Colt Industries Operating Corporation

Richard H Corrette

Improved thread rolling dies are disclosed forming fasteners with a cylindrical threaded portion and a threaded pointed portion. Such dies provide a polished rise angle surface for forming and threading the pointed portion of the fastener so as to promote slippage between such surface and the pointed portion of the fastener. The polished rise angle surface improves point formation, provide better filled threads, reduced burning of the fastener and increases die life. The dies also provide a match point spaced from the end of the short die so as to reduce the likelihood of improper timing when the dies are set up in the thread rolling machine. Further the dies provide an angulated top of the rise surface to break off any whiskers or tails which might otherwise project beyond the end of the point of the fastener being formed.

Thread rolling dies

Thread rolling dies for pointed fasteners having an improved working face contour which promotes displacement of blank material from the blank point area at an early stage in the thread rolling sequence to avoid excessive pressures in the die and blank at the finishing stages of the rolling sequence. Thread cutters include an extend section that presurfaces the rise angle of the die working face to produce uniform, improved thread profiles.

Cutter for thread rolling dies

Improved thread rolling dies are disclosed forming fasteners with a cylindrical threaded portion and a threaded pointed portion. Such dies provide a polished rise angle surface for forming and threading the pointed portion of the fastener so as to promote slippage between such surface and the pointed portion of the fastener. The polished rise angle surface improves point formation, provides better filled threads, reduces burning of the fastener and increases die life. The dies also provide a match point spaced from the end of the short die so as to reduce the likelihood of improper timing when the dies are set up in the thread rolling machine. Further the dies provide an angulated top of the rise surface to break off any whiskers or tails which might otherwise project beyond the end of the point of the fastener being formed.

Thread rolling dies for pointed fasteners having an improved working face contour which promotes displacement of blank material from the blank point area at an early stage in the thread rolling sequence to avoid excessive pressures in the die and blank at the finishing stages of the rolling sequence. Thread cutters include an extended section that presurfaces the rise angle of the die working face to produce uniform, improved thread profiles.

Thread rolling die construction

Method of producing thread rolling die

A method and apparatus for forming self tapping threaded fasteners having a cylindrical gripping portion and a tapered end portion with swaging lobes thereon is disclosed. The apparatus includes a pair of flat dies having a flat G-surface formed with thread rolling grooves therein to form the gripping cylindrical portion of the fastener. A rise angle surface having thread forming grooves therein with lobe forming recesses adjacent to the finished end operate to form the tapered point with lobes thereon. The G-surface is wider at the forward end of the die and progressively narrows until a dwell or finished portion is reached adjacent to the finish end of the die. Consequently, the threads along the tapered portion of the blank are not as fully formed as the threads along the cylindrical portion when the blank reaches the finishing end and excess material is available to fill the recesses and produce the lobes.

Thread rolling dies for forming self tapping screws and the like

A cylindrical through-feed thread rolling die having a tapered lead-in portion, a cylindrical dwell portion, and a tapered exit portion is disclosed. Such die provides uniform spacing between the crests of the thread forms thereon throughout the lengths of the die. The spacing between the roots of the die is uniform except at the junction between the dwell portion and the two tapered end portions, where a larger spacing exists between the roots of adjacent thread forms. Because the crest spacing on the thread forms of the die is uniformly maintained throughout the length of the die, excessive pressures do not exist at the junction between the dwell portion and the two end tapers, and drunken threads on the workpiece being rolled are virtually eliminated.

Method of forming through-feed cylindrical thread rolling dies

A thread rolling die and a method of thread rolling is disclosed for producing the annular rib on a threaded fastener suitable for retaining washers, clips or the like. The ends of the threads adjacent to such rib blend to the root diameter of the thread. The annular rib is produced by axially displacing workpiece material from the adjacent end of the thread. The die for rolling the thread is formed with thread forming grooves which extend to a base line spaced from the parallel to the lateral side of the die. At the base line the thread forming grooves fade to zero depth. Positioned between the base line and the lateral side of the die is a rib of increasing width which functions to displace material axially into the required rib.

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Cleveland, OH, United States of America

Richard H Corrette