Analysis of Factors Affecting Bore Accuracy of Hi-precision Cold-drawn Steel Pipe

Addressing the defects as staying with the hot-rolled pipe like poor bore ovality,serious wall thickness deviation and uneven steel hardness,etc.,the effect by the hot-rolled mother tube on the bore dimensional accuracy of the hi-precision cold-drawn steel pipe is analyzed.As a result,it is revealed that annealing of the mother tube helps for proper control of the cold-drawn tube’s bore ovality,so it is a must to use as-annealed or as-normalized mother tube for the cold-drawn tube production;the bigger the wall thickness deviation of the hot-rolled mother tube is,the bigger the deviations of both bore ovality and wall thickness of the subsequent cold-drawn tube will be,and the cold-drawing process can do nothing to eliminate the wall thickness deviation;and both the OD and ID dimensions and the ovality of the hot-rolled mother tube has but slight effect on the bore dimensional accuracy of the finished cold-drawn tube.