METHOD FOR CONTROLLING ROLLING WITH MANDREL MILL

摘要

PURPOSE:To eliminate the influence of the wall thickness, outside diameter and deformation resistance of a hollow pipe stock and the fluctuation in the diameter of a bar on the wall thickness and sectional area of a product and to improve the dimensional accuracy of the product by controlling simultaneously the number of revolutions and rolling reduction of rolls in the stage of rolling the hollow pipe stock by a mandrel mill. CONSTITUTION:The number of revolutions is operated to maintain the specified tension with respect to the wall thickness and outside diameter of the pipe stock, the deformation resistance of each stand and the disturbance owing to the fluctuation in the bar diameter of a mandrel 6 in front stage stands Nos. 2-5 so that the tension between the stands Nos. 2-5 of the front stage is made zero. The wall thickness is thus made constant. The rolling reduction of the rear stage stands Nos. 6-7 is controlled so as to correct the fluctuation in the wall thickness owing to the fluctuation in the bar diameter while the number of revolutions is so controlled as to make zero the tension between the respective stands with respect to the fluctuation in the bar diameter of the mandrel in the rear stage stands Nos. 6-7.