Thread-rolling head

In a thread-rolling head of the type wherein three identical support pieces, each including a pivot pin, a supporting journal, and a crank cheek, are rotatingly and non-dispaceably mounted by means of said pivot pins in three respective bearing bores uniformly distributed in a bearing member about the longitudinal axis of said thread-rolling head, each said crank cheek resting against an associated portion of a control surface forming part of a control member rotatable with respect to said bearing member, and each said supporting journal being cantilevered and projecting beyond said control member, and wherein each of three thread rollers is rotatingly borne on a supporting surface of an associated said supporting journal and is held axially between a shoulder surface of a said support piece situated immediately adjacent to a said crank cheek and a circlip disposed on said associated supporting journal, the improvement comprising:

• a V-shaped annular groove in each said supporting journal for holding a respective said circlip, each said groove having a flat side forming a shoulder situated adjacent to a said thread roller and a conical side having an outer diameter substantially equal to the diameter of said supporting surface of said associated supporting journal, each said circlip having a conical surface matching and resting against a said conical side of a said annular groove, and each said supporting journal having a flat end face situated flush with the face of each said circlip remote from each said thread roller.