影响高精度冷拔管内孔尺寸精度的因素分析

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

针对热轧管内孔椭圆度差、壁厚偏差大、材料硬度不均匀等问题,分析了热轧管料对高精度冷拔管内孔尺寸精度的影响。分析结果表明:热轧管料退火有利于控制冷拔管的内孔椭圆度,冷拔生产必须选择退火态或正火态的管料;热轧管料壁厚偏差越大,生产出的冷拔管内孔椭圆度和壁厚偏差就越大,通过冷拔无法消除其壁厚偏差;热轧管料内外径尺寸及椭圆度对冷拔成品内孔尺寸精度没有明显的影响。

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.