| 摘要 |
PURPOSE:To obtain a product with high dimensional accuracy by introducing a blank material having oval cross-sectional shape to a row of rolling mills formed by arranging alternately four sets of vertical and horizontal mills and performing the rollings of slight rolling reductions by three sets of the mills located at the inlet side before subjecting the material to a finish rolling of normal rolling reduction. CONSTITUTION:A blank material 1 having oval cross-sectional shape is introduced to a row of rolling mills formed by arranging alternately four sets of horizontal and vertical roll stands, to perform respectively the rollings of slight rolling reductions of 0.5-5%, 3-8%, and 0.5-5% reduction rate of area at the 1st-3rd stands, and the material 1 is subjected to the rolling of normal rolling reduction at the 4th stand. Further, the calibers to be provided to respective rolls are positioned so that the major-axis side of the material 1 at the 1st stand, the minor-axis side of a blank material 3 at the 2nd stand, and the major-axis side of material 3 are parallel to a roll axis respectively, and a caliber having circular cross-sectional shape 4 is provided to the roll at the 4th stand. In this way, a rolled product having a circular cross section of + or -0.004-0.05mm. dimensional accuracy is obtained.
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