JPS632532U - - Google Patents

Description

[Brief explanation of the drawing]

Fig. 1 is a plan view of an embodiment of the present invention, Fig. 2 is an enlarged front view of the thread-shaped part during thread rolling, Fig. 3 is an enlarged sectional plan view of the main part, Fig. 4 a, b and c are cross-sectional plan views of essential parts showing the thread rolling process, and FIG. 5 is a plan view of the thread-shaped portion of the thin-walled steel pipe in the thread rolling state in a conventional example.

Claims (1)

[Scope of utility model registration request] In a steel pipe end thread rolling device that presses and rolls the circumferential surface of a steel pipe end onto a rotating thread mold to form a concave thread on the steel pipe end, a cylindrical shaft is inserted between the thread molds coaxially with the rotatable steel pipe chuck. If the inner diameter between the threaded protrusions in the end of a pivotally connected and threaded steel pipe is d, then the base end of a semi-rigid elastic plastic cylinder having an outer diameter D smaller than the inner diameter d is the cylinder axis. A core shaft having an outer diameter E slightly smaller than the inner diameter d can be inserted and removed concentrically into the plastic cylinder, and when the coaxial shaft is inserted, the plastic cylinder expands. , a steel pipe end thread rolling device that is designed to come into close contact with the inner surface of the steel pipe end before chucked thread forming.