Patent ID: 7171838
Filing Date: 2007-02-06
Classification: B21D,B21K

Abstract:
1. A method for forming a thin walled tubular member with thickened flange portion, comprising: providing blank of a plate shape; subjecting the plate shaped blank to a first stage drawing process by using a drawing die of conical shape in such a manner that a cup shaped semi-finished product having an inclined free end portion located on a conical surface of the drawing die is obtained; and subjecting said cup shaped semi-finished product to a second stage drawing process so that a cup shaped part of the semi-finished product is secondary drawn, while flattening said inclined free end portion of said semi-finished product, thereby obtaining a tubular product with a thickened flange portion, wherein, during the execution of flattening of said end portion of the semi-finished product, limiting in the outer diameter of the end portion of the semi-finished product to a predetermined value is done, thereby obtaining additionally increased thickness of the flange portion of the tubular product, and wherein, during the second stage drawing of the cup shaped part, an additional simultaneous drawing is done for obtaining a stepped part at a location below the portion of the cup shaped part of said reduced thickness.