Patent ID: 7455512
Filing Date: 2008-11-25
Classification: B29C,B29L,Y10T

Abstract:
1. A mold assembly for manufacturing a heavy duty plastic hollow board, comprising: a first mold with a mold cavity on the inner surface thereof; a second mold aligned opposite to the first mold also having a mold cavity on its inner surface facing the first mold; and a movable mold associated to the outer surface of the second mold which is movable for a predetermined distance apart from the second mold and is having a plurality of protruding rib-forming members to be received by a plurality of matching through holes provided on the second mold, wherein, when the movable mold, gets relatively distant from, or alternatively, close to the second mold, the rib-forming members thereby thread through the through holes and protrude into the cavity of the second mold, or alternatively, completely isolate from said cavity wherein devices for driving the movable mold to and fro include: a linear actuator attached to the rear of the movable mold for providing a thrust to push the movable mold towards the second mold and a plurality of spring assemblies distributed over the movable mold for providing a restoring force opposite to said thrust, wherein each spring assembly includes a bolt fixedly fastened to the movable mold and receivable by the second mold, and a spring which envelops the bolt with both ends respectively butt on either the second mold or the movable mold.