Apparatus for forming plastic sheets

Claim 2

A vacuum forming machine for vacuum forming plastic articles from plastic sheet material comprising: a plurality of independently movable forming frame means for carrying plastic sheet material to various processing stations and for supporting the plastic sheet material at the processing stations, endless track means for guiding said movable frame means, processing apparatus for processing the sheet material located in spaced relationship at a plurality of processing stations spaced along said track means, drive means for advancing said frame means along said track means from station to station for processing of the plastic sheet material by said processing mechanisms and means for individually and selectively coupling each of said frame means to said drive means.

Claim 3

The invention as defined in claim 1 and wherein said forming frame means comprises: a four-sided frame defining an enclosed forming space, releasable clamping means on said frame means for clamping plastic sheet material in a forming position extending across said forming space and being movable therewith oN said track means, and clamp actuating means on said frame means operable between an open release position and a closed clamping position at one of the processing stations.

Claim 4

The invention as defined in claim 2 and wherein said clamping means comprises: a clamp surface extending along each side of said frame, and a clamping bar movably mounted on each side of said frame in cooperative clamping relationship with each clamping surface.

Claim 5

The invention as defined in claim 3 and wherein said clamp actuating means comprising: a movable actuating shaft means mounted on one side of said frame and being located between opposite sides of said frame, control linkage means operably connected to and extending from said movable actuating shaft means toward the opposite sides of said frame, movable support shaft means extending along each of the opposite sides of said frame and movably supporting a clamping bar extending along each of the opposite sides of said frame, and connecting means operably connecting said control linkage means to said movable support shaft means whereby actuation of said actuating shaft means actuates each clamping bar between the closed clamping position and the open release position.

Claim 6

The invention as defined in claim 4 and wherein said clamp actuating means further comprises: force applying means separate from and fixedly mounted relative to said frame at one of the processing stations, and movable support means for said force applying means for moving said force applying means into and out of force applying engagement with said movable actuating shaft means at the one of the processing stations.

Claim 7

The invention as defined in claim 5 and wherein said circular track means comprises an inner circular support rail and an outer circular support rail, a toroidal processing spaced defined by said inner circular support rail and said outer circular support rail, and said forming space being located between said inner circular support rail and said outer circular support rail in alignment with said toroidal processing space.

Claim 8

The invention as defined in claim 6 and said frame being movably supported at three points on said circular track with one suspension point located on one circular support rail and the other two suspension points being located on the other circular support rail.

Claim 9

The invention as defined in claim 3 and there being upper and lower sets of clamping bars and clamp actuating means extending along each side of said frame.

Claim 10

The invention as defined in claim 8 and there being two sets of force applying means simultaneously operable to open and close said clamping bars.

Claim 11

The invention as defined in claim 4 and adjustable mounting means for said clamping bars and said actuating means whereby the position of said clamping bars and said actuating means relative to said frame may be varied between a position defining a forming space of maximum area and a position defining a forming space of minimum area.

Claim 12

The invention as defined in claim 10 and wherein said adjustable mounting means comprises: sectionalized, removable and replaceable plate members providing said clamping surface and being removably attached to said frame, and sectionalized, removable, and replaceable clamping bar members being removably attached to said movable support rod means.

Claim 13

The invention as defined in claim 4 and said clamping means having only mechanically actuable parts.

Claim 14

The invention as defined in claim 1 and said processing apparatus comprising: a load and unload station whereat unformed plastic sheet material is clamped to said frame means and whereat formed plastic sheet material is removed from said frame means, a heating station whereat the unformed plastic sheet material is heated to a formable state, and a vacuum forming station whereat the heated plastic sheet material is vacuum formed into the desired shape.

Claim 15

The invention aS defined in claim 1 and having drive means for moving said frame from station to station along said track means and comprising: a movable drive ring movably supported adjacent said track means, connecting means for releasably drivably connecting said drive ring to said frame means, drive gear means drivingly connected to said drive ring, and motor means drivingly connected to said drive gear means and operable to drive said drive gear means and move said drive ring means a predetermined distance.

Claim 16

The invention as defined in claim 14 and said connecting means operating by harmonic motion to start movement of said frame with uniformly increasing speed and to stop movement of said frame with uniform decreasing speed.

Claim 17

The invention as defined in claim 14 and wherein said drive means being mounted adjacent the inside of said track means.

Claim 18

The invention as defined in claim 14 and said track means comprising an inner circular support rail and an outer circular support rail, and said processing apparatus being mounted between said inner support rail and said outer support rail.

Claim 19

The invention as defined in claim 14 and having locking means to lock the frame means to the track means at the processing stations.

Claim 20

The invention as defined in claim 14 and wherein said connecting means comprises: drag pin means fixedly mounted on said frame means, an arm engageable with said drag pin means and pivotally mounted on said track means for movement between a holding position and a release position relative to said drag pin means, and a pin seat on said arm receiving and holding said drag pin means in the holding position.

Claim 21

The invention as defined in claim 1 wherein said processing apparatus includes a press having at least one platen guided for vertical movement by a plurality of guide elements located on opposite sides of said track means.

Claim 22

The invention as defined in claim 1 in which said drive means comprises an oscillatory member movable in forward and reverse directions and means for uncoupling all of said forming frame means during movement of said drive means in the reverse direction.

Claim 23

The invention as defined in claim 1 in which said drive means comprises a ring member having separate and individually actuatable latches each of which is engageable with one of said forming frame means.