Patent ID: 6877652
Filing Date: 2005-04-12
Classification: B21C,B21G,Y10T

Abstract:
1. A method of manufacturing a side hole-bearing tubular body made of metal and having an inside diameter of up to 2 mm, comprising: punching from a metal sheet a sheet blank in the developed shape of a tubular body and punching in the sheet blank a hole which corresponds to the side hole in the tubular body or notches which form the side hole when the sheet blank is pressed into a tubular shape, or both, in such a way that the metal sheet and the sheet blank remain partly joined; pressing the sheet blank into a tubular shape possessing an inside diameter of up to 2 mm, with an inner surface of the tubular shape steel blank having a maximum difference between highest and lowest smoothness values of up to 3 μm as determined according to JIS B-0601 (1994) after press forming; and cutting apart the metal sheet and the sheet blank where they remain joined.