Matsushita Electric Industrial Co., Ltd.

Motoo Ohmori

Takashi Ogawa

Kenji Kobayashi

Tetsunori Matsuwaka

Hiroshi Hanafusa

Tomonobu Ogino

An aluminum alloy ring (the outside diameter D.sub.1) which is an element of a rotary head cylinder, is inserted in a cavity (the inside diameter D.sub.2 &gt;D.sub.1) of a fixed metal mold, with a clearance gap (D.sub.2 -D.sub.1) Then, the cavity of the fixed metal mold is closed by a movable metal mold, and the inner space of the aluminum alloy ring is filled with molten synthetic resin material. The filling resin is pressurized so that the aluminum alloy ring elastically expands until the outer diameter thereof D.sub.1 becomes exactly or almost equal to D.sub.2. After that, the filling synthetic resin material is cooled. Thus, the aluminum alloy ring and the synthetic resin material are integrated, resulting in a rotary head cylinder molding.

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Akaiwa, Japan

Motoo Ohmori