Appts. for folding and welding thermoplastic-lined carton tops - giving reliable sealing of prefilled milk packs, etc.

摘要

The cartons are made of card having a thermoplastic coating at least on the internal faces of the flaps which comprise the top of the container and which creased and folded to resemble an open mouthed ridge with two convergant curved sloping faces. The equipment incorporates curved jaws of which one is pointed in cross-section so that the flaps can be pressed together while being inclined w.r.t. the vertical axis of the container. The internal surfaces are preheated by hot air jets until hot enough to weld when compressed between the jaws. The pressure jaws are water cooled. The device is esp. for sealing square or rectangular plan cartons, opt. with a trapezoidal elevation, prefilled with milk or similar liq. The rotary jaws smoothly engage and release cartons advancing successively stepwise between twin chain conveyors, are less prone to distort or topple the container than use of stiff or static fold manipulation jaws. The folding and welding actions are reliable.