US 11,795,986 B2
External screw member
Minoru Sugiyama, Hadano (JP); Shigeto Mori, Hadano (JP); Mayumi Matsuno, Hadano (JP); and Naoki Horiuchi, Hadano (JP)
Assigned to TOPURA CO., LTD., Hadano (JP)
Filed by TOPURA CO., LTD., Hadano (JP)
Filed on Jan. 27, 2021, as Appl. No. 17/160,151.
Claims priority of application No. 2020-011669 (JP), filed on Jan. 28, 2020.
Prior Publication US 2021/0231157 A1, Jul. 29, 2021
Int. Cl. F16B 25/00 (2006.01); F16B 5/00 (2006.01)
CPC F16B 5/0052 (2013.01) 18 Claims
OG exemplary drawing
 
1. An external screw member comprising a parallel screw portion and a tapered screw portion provided on a side further toward a tip end than the parallel screw portion, wherein
a plurality of sets of a step portion and a transition screw thread portion are provided on at least one of the parallel screw portion and the tapered screw portion, the step portion having a reduced thread height in a radial direction and the transition screw thread portion gradually increasing in diameter from the step portion in an anti-driving rotation direction so as to reach a maximum diameter portion of the transition screw thread portion, and
a top portion of the transition screw thread portion in a minimum diameter portion of the step portion is positioned at an offset toward a pressure side relative to a position of a screw pitch of the maximum diameter portion of the transition screw thread portion, and the top portion of the transition screw thread portion transitions to the maximum diameter portion as the diameter thereof increases in the anti-driving rotation direction.