Patent ID: 6260271
Filing Date: 2001-07-17
Classification: B21C,B21D,B23P,F28F,Y10T

Abstract:
A production method of a tubular body having integral branch tubes from a single sheet metal by deformation processing comprising:a swelling step for creating a cylindrically swelled portion having a predetermined length and thickness, a top end of which being closed;a boring step for boring said top end of said swelled portion;a channel forming step for forming a mating channel extending in a longitudinal direction throughout the whole length of said sheet metal at an optional position in a transversal direction of said sheet metala rounding step for rounding said sheet metal in the transversal direction to form a tubular body having a desired sectional shape;a thickness increasing step for increasing the thickness of said sheet metal at the position where said mating channel is created; anda mating step for mating both ends of said rounded sheet metal with said mating channel thereby fixing the sectional shape of said tubular body.