Patent ID: 6219919
Filing Date: 2001-04-24
Classification: B62K,Y10T

Abstract:
A method of manufacturing a tapered rectangular pipe for a vehicle comprising the steps of:first, extruding a rectangular raw pipe having a rectangular sectional surface and an inner space being defined within the rectangular raw pipe, wherein the inner space of the rectangular raw pipe being divided into a plurality of segments by integral partition walls extending in a longitudinal direction within the inner space of the rectangular raw pipe; andsecond, forming at least a partial wall surface of the rectangular raw pipe into a tapered shape in a longitudinal direction without folding the partial wall, wherein at least two chambers are formed within the rectangular raw pipe by the integral partition walls, each of the at least two chambers having side walls and one of the chambers having a tapered wall surface and one of the chambers being without a tapered wall surface, in which a side wall of the one chambers without a tapered wall surface is made with a thinner wall thickness than a side wall of a chamber having a tapered wall surface.