Apparatus for making high strength open bottom packaging tray

Abstract

A tray of molded pulp or the like for packaging meat, poultry or fish in conjunction with an overwrap transparent film and the method and apparatus for making the tray. The tray bottom is formed of a plurality of generally vertical ribs joining or intersecting in two directions and defining open windows therebetween, the height of each rib being on the order of several times the thickness of the remainder of the tray, the side and end walls having double sloped portions, and the total volume of the ribs being approximately equal to the volume of a bottom of an imperforate bottom tray of the same size. The method of making a tray including the steps of (a) taking a wet preform of molded pulp or the like formed in an open bottom construction with a plurality of inverted V or U-shaped ribs joining or intersecting in two directions and defining open windows therebetween and pressing the side walls of the V or U-shaped ribs together to impart to said ribs the form of generally vertical ribs with parallel side wall portions, and (b) drying the tray under controlled conditions to final form for storage or shipment. The apparatus for making a tray comprising a male forming die member including a plurality of rib grooves joining or intersecting in two directions into which a wet preform of molded pulp or the like may be transferred; a stuffing element for effecting initial seating of the rib members of the wet preform within the rib grooves; and female press die member with a plurality of insert plugs for pressing the ribs of the preform into the rib grooves of the male die member into fully seated relationship whereby final shape of the tray is imparted to the preform.