US 4,207,051 AGranted

Stripper mechanism for injection mold

AssigneeHusky Injection Molding Systems Ltd.

InventorsJohn B. Wright, Robert D. Schad

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Abstract

An injection-molding machine has a fixed and a movable outer platen bracketing a movable intermediate platen, the latter having a runner system conducted via an extensible or flexible conduit to a source of molten plastic material to be injected into cavities defined by respective pairs of mold portions supported by the three platens, the cavities being formed in part by cores carried on the outer mold portions. A stripper plate inserted between each pair of mold portions is articulated via a spring-loaded lost-motion link to a respective eccentric pin on a pinion which is rotatably mounted on the intermediate platen and meshes with a pair of racks respectively secured to the two outer platens; this linkage is duplicated on opposite sides of the mold. In an initial phase of a mold-opening stroke, the stripper plates move outwardly under spring pressure while remaining in contact with their respective outer mold portions whose cores still retain the freshly molded articles. When the limit of the lost-motion travel is reached, the stripper plates are slowly lifted off their adjoining mold portions to detach the molded articles from the cores.

Claims10

Dependent claims

In an injection-molding machine having a plurality of relatively movable platens including a first platen carrying a first mold portion and a second platen carrying a second mold portion, said first mold portion being provided with a projecting core receivable in a mold-closed position in a recess of said second mold portion for defining therewith an injection cavity,

the combination therewith of a stripper plate penetrated by said core sandwiched between said first and second mold portions in said mold-closed position and mechanism for detaching said stripper plate from both said mold portions upon displacement of said platens into a mold-open position to disengage a molded workpiece from said core, said mechanism comprising:
a rack secured to said first platen and extending past said second platen in said mold-closed position;
a pinion rotatably journaled on said second platen in mesh with said rack;
resilient means urging said stripper plate into contact with said first mold portion at the beginning of a mold-opening stroke;
and
a link articulated at an eccentric location to said pinion and joined to said first platen by a lost-motion connection enabling limited separation of said stripper plate from said second mold portion whereby said stripper plate maintains contact with said first mold portion under the urging of said resilient means in an initial phase of said mold-opening stroke, said link coming into positive engagement with said stripper plate for breaking said contact at the end of said initial phase.

3 more elements

Dependencies are inferred from the claim text.