This invention relates to a conveyor for automatic processing of workpieces. One specific aspect by way of example and not limitation relates to a conveyor for the automatic heating, in an oven relying mainly on forced convection, of many square thin flat chips of polypropylene to a suitable temperature in connection with which the invention will be described.
An object of this invention is to provide means for conveying flat workpieces on removable trays on an endless type of conveyor through one or more processes.
In summary, the invention embraces a conveyor of the endless type having means for clamping and releasing carrier trays that comprises--a pair of parallel and spaced apart endless conveyors such as belts or chains and preferably (as described e.g. hereafter) chains, a plurality of annular rectangular frames connected to and between said chains at equally spaced-apart distances along each and having substantially flat upwardly facing support surfaces; at least one clamping means mounted on each said frame to clamp and release a carrier tray means thereto, a machine base from which said chains are supported to run longitudinally each in an endless path; and a clamp actuator in the form of a fixed cam mounted on said base at a position to engage each of said clamping means seriatim to cause it to release its tray at one position and to clamp its respective tray at another position, said clamping means and clamp actuators coacting to hold the clamping means in an unclamped position over a certain part of the path of said chains and to cause them to move to a clamped position during the other part of the path. In the preferred embodiment, a plurality of such carrier trays and each said carrier tray is a flat perforated member silicone rubber covered on at least one side.