Compound die for dual thread forming
OwnerMark Doll, Zebula Dollinventors
Life of this patent
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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.
Claims13
A compound die for forming a dual threaded screw, the compound die comprising in combination:
- a working surface extending between a front and a rear, and between two sides;
- said working surface including a coarse end with coarse crests and coarse roots adjacent said front;
- said working surface including a fine end with fine crests and fine roots adjacent said rear;
- said fine crests extending up from said working surface less than said coarse crests;
- said fine end is closer to said rear than said coarse end;
- and
- wherein said coarse end has a pitch angle that said coarse crests diverge from said sides defining the pitch angle for said coarse end, and said fine crests of said fine end are angled relative to said sides at a pitch angle of said fine end, said coarse end pitch angle twice said fine end pitch angle, wherein the pitch angle of the coarse crests of said coarse end is constant for all of said coarse end and the pitch angle for said fine crests of said fine end is constant for all of said fine end.
A compound die for forming a dual threaded screw, the compound die comprising in combination:
- a working surface extending between a front and a rear, and between two sides;
- said working surface including a coarse end with coarse crests and coarse roots adjacent said front;
- said working surface including a fine end with fine crests and fine roots adjacent said rear;
- said fine crests extending up from said working surface less than said coarse crests;
- said fine end is closer to said rear than said coarse end;
- wherein said coarse end has a pitch angle that said coarse crests diverge from said sides defining the pitch angle for said coarse end, and said fine crests of said fine end are angled relative to said sides at a pitch angle of said fine end, said coarse end pitch angle twice said fine end pitch angle, wherein the pitch angle of the coarse crests of said coarse end is constant for all of said coarse end and the pitch angle for said fine crests of said fine end is constant for all of said fine end;
- wherein a transition exists between said coarse end and said fine end where said working surface transitions from said coarse crests and said coarse roots to said fine crests and said fine roots;
- and
- wherein said transition includes a concave slope extending from said coarse crests to said fine crests.
Dependencies are inferred from the claim text.