Apparatus for injection molding multilayered articles
AssigneeCommunity Enterprises, LLC
InventorJoel Thomson
Life of this patent
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Abstract
An apparatus for injection molding two compatible polymeric materials, in which two or more plasticizing zones on a screw are used to simultaneously or sequentially plasticize the two materials into a common accumulation space through separate pathways. The charge comprising multiple layers of material is then injected into a closed mold by means of forward axial motion of the screw with respect to its enclosing barrel. Once inside the mold, the first material forms a skin layer, totally or partially surrounding the other material. In this way a part having a plurality of material properties may be produced in a single operation.
Claims16
A device for melting polymeric material, comprising:
- a barrel having an upstream end and a downstream end;
- a first material source;
- a second material source;
- a screw having at least a first plasticizing zone extending along a first length of an exterior portion of the screw for plasticizing material from the first material source to convey a first melt toward the downstream end, and a second plasticizing zone extending along a second length of the exterior portion of the screw for plasticizing material from the second material source to convey a second melt toward the downstream end, such that the first length and the second length are non-overlapping portions of the screw;
- separation means extending at least along the exterior portion of the screw between the first length and the second length for separating the first melt from the second melt;
- and
- an accumulation space for receiving the first melt and the second melt, each melt separately conveyed from the respective plasticizing zone.
An injection molding machine comprising:
- a first material source;
- a second material source;
- a screw having at least a first plasticizing zone extending along a first length of an exterior portion of the screw for plasticizing material from the first material source to output a first melt into a first accumulation space, and a second plasticizing zone extending along a second length of the exterior portion of the screw for plasticizing material from the second material source to output a second melt into a second accumulation space;
- and
- a moveable barrier for separating the first accumulation space and the second accumulation space.
A method of producing molded objects with a composite structure comprising a core layer and a skin layer comprising the following steps:
- rotating a screw having a longitudinal axis:
- (1) to melt first material in a first plasticizing zone extending along a first length of an exterior portion of the screw and to cause melted first material to flow through a conduit and a first non-return valve into an accumulation space in front of the screw;
- and (2) to simultaneously melt second material in a second plasticizing zone extending along a second length of the exterior portion of the screw to cause melted second material to flow through a second non-return valve into the accumulation space in front of the screw such that one of the first material and the second material form substantially toward the rear and outer periphery of the accumulation space thereby forming a composite shot, the composite shot forcing the screw back along the longitudinal axis;
- and
- injecting the composite shot into a mold.
Dependencies are inferred from the claim text.