Non-working safety belt pretensioners development of high-precision cold forging process technology and key component parts

摘要

The present invention relates to a method of manufacturing a seat belt pretensioner wheel gear, comprising the steps of: preparing a cylindrical blank (B) by cutting a round steel bar; A first heat treatment step (S20) of annealing and softening the blank (B); A first coating step (S30) of coating the softened heat-treated blank (B) with a coating agent; The formed cylindrical blank B is forged to form the first formed body S1 having the gear tooth 1 at the outer peripheral portion of the first cylindrical body 5 and the intermediate concave circular bottom face portion 3 Forming a preliminary forging step (S40); After the first formed body S1 is positioned in the piercing mold, the circular bottom face portion 3 is pierced to form a through groove 13 at the center and gear teeth 11 are formed on the outer peripheral portion of the second circumferential body 15 A piercing step S50 for molding the second formed body S2; A third heat treatment step (S60) of annealing and softening the second formed body (S2); A third coating step (S70) of coating the softened heat-treated second formed body (S2) with a coating agent; The second formed body S2 is cold-forged to form a through groove 23 formed at the center of the third circumferential body 25 and a gear tooth 21 formed at the outer circumferential portion and a groove width 21 along the inner circumferential portion The ball grooves 27 and the ball supporting grooves 27 corresponding to the ball grooves 27 are formed so that the shape of the ball grooves 27 becomes larger and the groove width becomes larger and smaller, And a final forging step (S80) of forming a third formed body (S3) provided with the first and second formed bodies (27a, 27a).