Patent ID: 9643237
Date: 2017-05-09
CPC Classifications: B21H,B23G

Claim:
1. 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.