Rotary head cylinder produced by injection of pressurized resin

A rotary head cylinder comprising:

• an aluminum alloy ring, and
• a synthetic resin material molded in the inner space of said aluminum alloy ring and integrated therewith, and which resin has both a small molding-shrinkage and a coefficient of linear thermal expansion similar to that of said aluminum alloy, wherein said synthetic resin material contains carbon fibers.

A rotary head cylinder comprising:

• an aluminum alloy ring, and
• a synthetic resin material molded in the inner space of said aluminum alloy ring and integrated therewith, and which resin has both a small molding-shrinkage and a coefficient of linear thermal expansion similar to that of said aluminum alloy, wherein said synthetic resin material contains glass fibers.

A rotary head cylinder comprising:

• an aluminum alloy ring, and
• a synthetic resin material molded in the inner space of said aluminum alloy ring and integrated therewith, and which resin includes electrically conductive substances.

A rotary head cylinder comprising:

• an aluminum alloy ring, and
• a synthetic resin material molded in the inner space of said aluminum alloy ring and integrated therewith, and which resin includes conductive substances, wherein said synthetic resin material is one selected from the group consisting of polyether imide, liquid crystal polymer and polycarbonate.

A rotary head cylinder comprising:

• an aluminum alloy ring, and
• a synthetic resin material molded in the inner space of said aluminum alloy ring and integrated therewith, and which resin includes conductive substances, wherein said synthetic resin material contains carbon fibers.

A rotary head cylinder comprising:

• an aluminum alloy ring, and
• a synthetic resin material molded in the inner space of said aluminum alloy ring and integrated therewith, and which resin includes conductive substances, wherein said synthetic resin material contains glass fibers.

A rotary head cylinder comprising:

• an aluminum alloy ring, and
• a synthetic resin material molded in the inner space of said aluminum alloy ring and integrated with said aluminum alloy ring, said ring being elastically expanded radially by 0.1 to 0.4 mm at a time when said synthetic resin material is molded and pressurized in an inner space of said ring, whereby an integration of said synthetic resin material with said ring is improved after said synthetic resin has solidified, and wherein said synthetic resin material is one selected from the group consisting of polyether imide, liquid crystal polymer and polycarbonate.

A rotary head cylinder comprising:

• an aluminum alloy ring, and
• a synthetic resin material molded in the inner space of said aluminum alloy ring and integrated with said aluminum alloy ring, said ring being elastically expanded radially by 0.1 to 0.4 mm at a time when said synthetic resin material is molded and pressurized in an inner space of said ring, whereby an integration of said synthetic resin material with said ring is improved after said synthetic resin has solidified, and wherein said synthetic resin material contains carbon fibers.

A rotary head cylinder comprising:

• an aluminum alloy ring, and
• a synthetic resin material molded in the inner space of said aluminum alloy ring and integrated with said aluminum alloy ring, said ring being elastically expanded radially by 0.1 to 0.4 mm at a time when said synthetic resin material is molded and pressurized in an inner space of said ring, whereby an integration of said synthetic resin material with said ring is improved after said synthetic resin has solidified, and wherein said synthetic resin material contains glass fibers.