Method of producing bowl-like metal article

A method of producing a bowl-like metal article, comprising the steps of:

• shaping a metal blank in the form of a circular plate into a bowl-like member having a concave inner surface and an open end by a press forming operation;
• correcting the shape of said bowl-like member by a spinning operation;
• after the shape correcting step, securing said bowl-like member in a region near the open end to a transferable annular base support means;
• securing a templet member, having a convex outer surface shaped to correspond to said concave inner surface of said bowl-like member and formed of material having a coefficient of expansion greater than the coefficient of expansion of the material of said bowl-like member and made such that when said bowl-like member and said templet member are cooled together from an elevated temperature said templet member will cool at a lower rate than said bowl-like member, to said support means so that said convex outer surface of said templet member is initially at such a short distance from said concave inner surface of said bowl-like member that when said bowl-like member and said templet member are heated to a predetermined temperature said convex outer surface comes into contact with said concave inner surface of said bowl-like member by thermal expansion;
• heating said bowl-like member together with said templet member while they are secured to said support means to a heat treatment temperature which is an elevated temperature not lower than the predetermined temperature, to keep said bowl-like member in a restrained state and correct irregular straining and distortion of said bowl-like member under heat treatment;
• and
• rapidly cooling the heated bowl-like member together with said templet member while said convex outer surface of said templet member is still in contact with said concave inner surface of said bowl-like member.