Abstract A machine for forming thin plastic packaging trays of dished configuration with an upper peripheral edge which lies within a single plane. The machine includes a plurality of flat faced vacuum form molds carried on the periphery of a rotating drum. A ribbon of plastic material is continuously delivered to the drum and mechanically clamped to the surface of each mold in consecutive order as the drum rotates. Each section of clamped ribbon is carried past a radiant heater and a vacuum is then applied to draw the softened plastic into the mold. The clamps are disengaged and the trays are held in the molds by a continued application of vacuum while a heated blade moving in a repetitive closed curvilinear path severs the ribbon between adjacent trays and while a pair of rotating knives trim the edges of the trays. A vacuum operated picker removes the trays from the drum and deposits them on a conveyor.
Apparatus for clamping a sheet of material to the peripheral surface of a rotary drum comprising in combination first and second jaw members pivotally mounted to opposite sides of said drum to be movable toward and away from the peripheral surface of the drum, stationary cam means positioned adjacent one side only of said drum, a cam follower engaging said cam means, and means connected to said cam follower and to said jaw members to pivot said jaw members in response to movement of said cam follower radially with respect to the drum.
Claim 2
Dependent Claim
93 words
Apparatus for clamping a sheet of material to the peripheral surface of a rotary drum comprising in combination first and second jaw members pivotally mounted to opposite sides of said drum to be movable toward and away from the peripheral surface of the drum, stationary cam means positioned adjacent one side only of said drum, a cam follower engaging said cam means, and means connected to said cam follower and to said jaw members to pivot said jaw members in response to movement of said cam follower radially with respect to the drum.
Claim 3
Dependent Claim
62 words
Apparatus according to claim 1 wherein said last mentioned means includes a rotatable shaft extending through said drum, means for interconnecting said cam follower with said shaft to cause said shaft to rotate in response to movement of said cam follower radially with respect to the drum, and means for pivoting said jaw members in accordance with the rotation of said shaft.
Claim 4
Dependent Claim
71 words
Apparatus according to claim 2 wherein a first link arm is mounted on one end of said shaft to rotate therewith and is connected to said cam follower, a first linkage connects said first jaw member with said first link arm, a second link arm is mounted on the other end of said shaft to rotate therewith, and a second linkage connects said second jaw member to said second link arm.