| 摘要 |
PURPOSE:To improve the shape and size accuracy of a rolled stock pipe by forming a roller shoe to a larger diameter from the terminal of the roller shoe where there is no more contact of the rolled stock pipe and plug toward an outlet side and subjecting the stock pipe to specific diametral reduction. CONSTITUTION:The roller shoe 22 is formed by attaching a tapered roll having length l and max. outside diameter d1 to the roller shoe near the terminal thereof. The max. diameter d1 of the tapered part is so determined that the difference between the outside diameter d0 at the terminal of the shoe 22 and the max. outside diameter d1 of the tapered part; i.e., the outside diameter reduction rate DELTAd of the rolled stock pipe 36 is as shown by DELTAd>=0.02Df (where, Df is the outside diameter of the rolled stock pipe on the outlet side). The length l of the tapered part is, therefore, set at the forward slip of the half-turn of the rolled stock pipe or above. Since tension is thereby applied to the outside surface of the rolled stock pipe on the outlet side of the shoe 22, the waving on the outside surface is prevented. Since an effect of improving the uneven wall thickness is provided, the shape and size accuracy of the rolled stock pipe 36 is improved.
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