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Abstract

A method of making an elastic thread having a closed cavity inside the thread profile comprises plastically deforming the walls of a preformed helical groove by means of a thread-forming tool (2). The helical groove is made at least double-start and having a pitch equal to that of the thread to be formed, one of the starts serving for directing the thread-forming tool (2) which, during the process of plastically deforming the walls of the helical groove, transforms each of the remaining starts into a closed helical cavity (3) disposed inside the thread profile. A thread-forming tool for practicing the above described method comprises threading rollers (7) having a circular thread and uniformly disposed around a circumference in a body (4) provided with a starting portion (5). Groove-forming rollers (6) are uniformly disposed around a circumference at the side of the starting portion (5) of the body (4) and in front of the threading rollers (7), said groove-forming rollers being provided with a circular thread having a pitch equal to P/n, where P is a pitch of the thread to be rolled, and n.gtoreq. 2 is a number of the starts of the helical groove.

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First Claim