PURPOSE: To make the pass-production possible and to make the loss of stock little by making the stock into solid solution, forming the formed body by applying the twisting force along the center line and then making the formed body into solid solution.

CONSTITUTION: The first process is that the stock is made into the solid solution and softened. The second process is that one end of the stock is fixed and the twisting force is applied from the out part by fixing only the near part of the center line of the other end. The 3rd process is that the spiral shaped body formed at the 2nd process is made into the solid solution in order to remove the strain. The breakage of intermolecule bonding of the outer circumference can be prevented by fixing the central part at the twisting process.