Patent ID: 6183013
Filing Date: 2001-02-06
Classification: B21D,B62D

Abstract:
A method of making a frame side rail for a vehicle frame comprising:pre-bending a constant diameter cross-section tubular member to a configuration having a first end section, a center section and a first transition section joining the end section and the center section to substantially the same as a desired final shape of the frame side rail;pre-expanding said center section to an increased diameter and said transition section of said pre-bent tubular member to a new configuration, having one end portion thereof with a diameter equal to the end section and another end portion thereof equal with the increased diameter of said center portion, in a single hydroforming process; andhydroforming the pre-expanded tubular member into a side rail of substantially rectangular cross-section with said end section having a first wall thickness, said center section having a second wall thickness less than said end section and said transition section having a varying wall thickness which is equal to the first end section wall thickness at a first position adjacent thereto and equal to the center section wall thickness at a second position adjacent thereto.