Cold-roll forming of small-diameter pipes with pre-notches

Small steel pipes with 4.0 mm diameters have been formed from pre-notched sheet plates using a cold-roll forming machine. Small-diameter pipes or tubes in great variety have been widely used in electronics, medical instrumentation, and automotive and aircraft industries. It is now commonly recognized that improvements in quality and productivity of the products have been the main concern in industries. This paper deals with a method of manufacturing small-diameter steel pipes with pre-notches by applying the process of cold-roll forming. In order to prevent shape defects that occur during the formation, the accuracy of the formed small pipes was examined in terms of the dimensions of the pre-notch. To clarify the mechanism causing the shape defects, the relationship between roll-pass schedules and the accuracy of the products was investigated.