Patent ID: 6745610
Filing Date: 2004-06-08
Classification: B21C,B21K,B60G,B62D,Y10T

Abstract:
An arm production method for producing a cylindrical arm which will be connected to an adaptor portion and a connectable member and includes:a tubular first connecting portion provided at one end of the arm and adapted to be connected to said adaptor portion, a tubular second connecting portion provided at the other end of the arm and adapted to be connected to said connectable member, and a buckle portion which is smaller in diameter than the first connecting portion as well as the second connecting portion and provided between the first connecting portion and the second connecting portion so as to buckle when a load greater than a given value is applied to the first connecting portion or the second connecting portion, said method comprising steps of: forming an unfinished body by narrowing one end portion of a tubular material that has a diameter corresponding to that of either one of the first connecting portion or the second connecting portion so as to form said one end portion into a small diameter portion having a diameter corresponding to that of said buckle portion, and radially enlarging the portion between the end of the slender portion of the unfinished body and the portion of the slender portion to be formed into the buckle portion so as to increase the diameter to correspond to the diameter of the other one of the first connecting portion or the second connecting portion.