| 摘要 |
PURPOSE:To permit diametral reduction of a pipe with high accuracy by arranging plural pieces of tapered rollers to the tapered inner peripheral face of a rotary die and rotating the die so that the rollers make planatary motion around the metallic pipe. CONSTITUTION:Plural pieces of the tapered rollers 3 are arranged along the tapered inner peripheral face 2 of the rotary die 1 and while the metallic pipe 7 to be worked is fed continuously to the die 1, said die is rotated by a prescribed driving device. As a result, the tapered rollers 3 are friction-driven by the rotating force applied to the die 1 to make the planetary motion around the pipe 7, by which the pipe 7 is reduced in the outside diameter. Since the tapered rollers 3 have the shape corresponding to both radial and thrust loads, the rollers make linear contact with the inside surface of the rotary die and the stresses are thereby dispersed. The diametral reduction of the pipe is, therefore, executed with. high accuracy and efficiency.
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