Invention Grant
- Patent Title: Compound die for dual thread forming
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Application No.: US14218526Application Date: 2014-03-18
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Publication No.: US09643237B1Publication Date: 2017-05-09
- Inventor: Mark Doll , Zebula Doll
- Applicant: Mark Doll , Zebula Doll
- Agency: Heisler & Associate.
- Main IPC: B21H3/02
- IPC: B21H3/02 ; B21H3/06

Abstract:
The compound die includes a working surface with a coarse end for forming coarse threads and a fine end for forming fine threads. The coarse end has coarse crests and coarse roots thereon angled at a coarse thread pitch angle for the screw to be formed. The fine end has fine crests and fine roots formed into a working surface thereof at an angle matching a pitch angle for the fine threads of the screw to be formed. A transition is provided between the coarse end and fine end where each of the coarse roots is aligned with one of the fine roots. A screw such as a bolt is roll formed by first being rolled between a standard die parallel with the compound die and a course end of the compound die, followed by rolling between the standard die and the fine end of the compound die.
Public/Granted literature
- US1773333A Weighing scale Public/Granted day:1930-08-19
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