Abstract: A method and apparatus for manufacturing a multi-layer plastic product comprised of a hollow plastic core and an outer plastic layer formed on the core are provided. A mold has a plurality of segments and is provided with a plurality of supply ports arranged in a desired pattern. The mold is assembled with the hollow plastic core located in a mold cavity, and, then, a molten plastic material is supplied into the mold cavity through the plurality of supply ports. Then, the mold is set in its clamped condition to carry out shaping of the molten plastic material into the outer layer having a desired shape. Since the molten plastic material is supplied through a plurality of supply ports, the pressure inside the mold cavity during supply and shaping steps is maintained at a relatively low pressure level, preferably 200 kg/cm.sup.2, which is much lower than an ordinary pressure level used in injection molding.

Abstract: A hollow plastic member is disclosed suitable for the intake passageway for an automobile engine. A core member is provided formed of multiple layers by blow molding. The outer layer is formed around the core member by injection molding.

Abstract: A hollow plastic member is disclosed suitable for the intake passageway for an automobile engine. A core member is provided formed of multiple layers by blow molding. The core is then used to form the outer layer by injection molding.

Abstract: A plastic intake pipe for an internal combustion engine, has an inside pipe provided in the plastic intake pipe and formed integrally from the intake duct portion to the intake manifold portion, a supporting member inserted in the inside pipe for supporting an inside wall of the inside pipe for fixing the intake duct portion and the intake chamber, and an outside pipe for entirely covering the inside pipe. The intake pipe prevents itself from deforming and damaging while assembling in the internal combustion engine and provides a simple structure for handling.