Apparatus for molding articles

Claim 1

A clamping frame for supporting a sheet of thermoplastic material during the performance of an operation thereon, the combination comprising a frame, a first set of sheet-clamping devices movably supported by said frame, a second set of sheeT-clamping devices movably supported by said frame, said clamping devices in each of said first and second sets being linearly arranged with the clamping devices in said first set being arranged parallel to the clamping devices in said second set, a third set of sheet-clamping devices movably supported by said frame, a fourth set of sheet-clamping devices movably supported by said frame, said clamping devices in each of said third and fourth sets being linearly arranged with the clamping devices in said third set being arranged parallel to the clamping devices in said fourth set, said first and second sets extending transversely to said third and fourth sets, and a plurality of means interconnected between adjacent ones of said clamping devices in each of said sets for independently controlling the spacing between the clamping devices in each of said sets.

Claim 7

An apparatus for use in molding articles from a sheet of thermoplastic material, frame means defining a space, a plurality of spaced-apart clamping assemblies movably mounted on said frame means for holding the marginal edges of said sheet to support it in a planar configuration in said space, and means for moving said clamping assemblies relative to one another during heating of said sheet to stretch it in the plane of said sheet to maintain it in its planar configuration in said space so that the sagging of the heated sheet is prevented; wherein said frame means comprises a pair of spaced side members and a pair of end members joining said side members, further including track means connected to said frame means for supporting said clamping assemblies thereon, said track means comprising a pair of spaced side clamp tracks extending in a direction parallel to said side members and a pair of spaced end clamp tracks extending in a direction parallel to said end members; wherein said means for moving said clamping assemblies comprises a plurality of piston cylinder assemblies, each of said cylinder assemblies including a housing fixedly connected to one of the clamping assemblies and a piston rod reciprocably mounted in the housing, the outer end of said piston rod being connected to another one of said clamping assemblies to move the last-mentioned clamPing assemblies further apart to stretch the portion of said sheet between said last-mentioned clamping assemblies; wherein one of said side clamp tracks is a stationary clamp track rigidly connected to said frame means and the other one of said side clamp tracks is rollably supported by said frame means to roll toward and away from the stationary side track, one end of each of said end clamp tracks being rigidly connected to the rollably mounted side clamp track and the other end of said end clamp tracks being slidably supported by the stationary side clamp track and being fixedly connected to the end clamping assemblies mounted on the stationary clamp track so that the end clamp tracks move in unison with the end-clamping assemblies on the stationary clamp track, each of said end clamp tracks being connected to the rollably supported clamp track by a clamping assembly slidably mounted on the end clamp track, the last-mentioned clamping assembly being rigidly connected to the rollably supported side clamp track to move it in unison with said last-mentioned clamping device.

Claim 8

An apparatus for use in molding articles from a sheet of thermoplastic material, frame means defining a space, a plurality of spaced-apart clamping assemblies movably mounted on said frame means for holding the marginal edges of said sheet to support it in a planar configuration in said space, and means for moving said clamping assemblies relative to one another during heating of said sheet to stretch it in the plane of said sheet to maintain it in its planar configuration in said space so that the sagging of the heated sheet is prevented; wherein said frame means comprises a pair of spaced side members and a pair of end members joining said side members, further including track means connected to said frame means for supporting said clamping assemblies thereon, said track means comprising a pair of spaced side clamp tracks extending in a direction parallel to said side members and a pair of spaced end clamp tracks extending in a direction parallel to said end members; wherein said means for moving said clamping assemblies comprises a plurality of piston cylinder assemblies, each of said cylinder assemblies including a housing fixedly connected to one of the clamping assemblies and a piston rod reciprocably mounted in the housing, the outer end of said piston rod being connected to another one of said clamping assemblies to move the last-mentioned clamPing assemblies further apart to stretch the portion of said sheet between said last-mentioned clamping assemblies; wherein one of said side clamp tracks is a stationary clamp track rigidly connected to said frame means and the other one of said side clamp tracks is rollably supported by said frame means to roll toward and away from the stationary side track, one end of each of said end clamp tracks being rigidly connected to the rollably mounted side clamp track and the other end of said end clamp tracks being slidably supported by the stationary side clamp track and being fixedly connected to the end clamping assemblies mounted on the stationary clamp track so that the end clamp tracks move in unison with the end-clamping assemblies on the stationary clamp track, each of said end clamp tracks being connected to the rollably supported clamp track by a clamping assembly slidably mounted on the end clamp track, the last-mentioned clamping assembly being rigidly connected to the rollably supported side clamp track to move it in unison with said last-mentioned clamping device.