| 摘要 |
PROBLEM TO BE SOLVED: To raise the uniformity of the dimension of a hole part, to generate a raw material collected locally for forming the hole part to flow, and to reduce the friction of a die by a forming operation inside a closed die hollow part so as to be applied only with a minimum load and so that a few numbers of machining processes is needed in order to form a finished hole part. SOLUTION: In order to form a hole part 12 in a manifold of a heat exchanger, a standing tube 24 is return-extruded by one time working from the surrounding raw material of the manifold so that the following machinery process to further finish the hole part is eliminated. The manifold is forged between a pair of die half bodies 18a, 18b generally so that a part collected locally of the manifold is return-extruded. During the manifold remains inside the die hollow part, a punch 20 is moved forcibly so as to more return-extrude the extruded part. |
