Abstract: A blow molding method including a clamp for clamping two molds in back-to-back relationship, the clamp having first and second movable, inner platens supporting interior sections of two molds; first and second movable outer platens supporting exterior mold sections facing the interior sections; a positioner to move the inner and outer platens between opened and closed positions; an extrusion means to extrude parisons between mold sections, injectors to inject air into the interior of the parisons; and a platen retainer to resiliently position the inner platens between the outer platens to equalize pressure in the two molds.

Abstract: Large, multi-layer parisons with an inner layer, an intermediate layer, and an outer layer for use in intermittent extrusion blow molding are formed using a die head including a housing, an annular inner conduit having a first resin inlet with a horizontal axis, an intermediate conduit having a second resin inlet with a horizontal axis, and an annular outer conduit having a third resin inlet with a horizontal axis, a closable, tubular extrusion orifice in communication with the inner, intermediate and outer conduits, the first inlet being in a plane above the second inlet and the second inlet being in a plane above the third inlet; and first, second and third reciprocating screw extruders, each extruder including a cylinder with a resin inlet and a resin discharge outlet, a screw rotatable within the cylinder to convey the resin from the resin inlet to the discharge outlet, the screw being axially movable away from the outlet when the screw is rotating, and drive means for moving the screw rapidly toward the

Abstract: A blow molding apparatus including a clamp for clamping two molds in back-to-back relationship, the clamp having first and second movable, inner platens supporting interior sections of two molds; first and second movable outer platens supporting exterior mold sections facing the interior sections; a positioner to move the inner and outer platens between opened and closed positions; an extrusion means to extrude parisons between mold sections, injectors to inject air into the interior of the parisons; and a platen retainer to resiliently position the inner platens between the outer platens to equalize pressure in the two molds.

Abstract: A blow molding apparatus including a clamp for clamping two molds in fixed, back-to-back relationship, the clamp having a central platen supporting interior sections of two molds in a fixed, back-to-back relationship, and first and second movable platens supporting exterior mold sections facing the interior sections. The apparatus also includes a clamp positioner to move the movable platens between opened and closed positions, an extruder to extrude parisons between mold sections, injectors to inject air into the interior of the parisons, and a central platen retainer to resiliently position the central platen between the movable platens.