A rectangular tray-type carton formed from a blank of plastics-coated board has a peripheral flange for attachment of a closure lid. The flange is formed after the erection of the carton side wall in a punch and die arrangement, by folding down elongate panels carried along the free edges of the side wall and by subsequently joining the panels together at their ends by means of overlapping tabs which are heat-sealed together. In order to avoid damage to the tabs during formation of the side wall the uppermost tabs are folded out of the plane of the blank before it enters the punch and die arrangement.

Disclosed is a new machine for forming containers of the type described in U.S. Pat. No. 5,497,939 without the use of glue or nails. The machine utilizes a mandrel movably mounted on a path for oscillation between retracted and extended positions. As the mandrel cycles forward, it first receives two synthetic sidewalls and then a deformable body panel of the container to be formed. Then a set of moveable upper and lower rockers containing unique pressure mechanisms press tabs on the horizontally oriented portion of the wrap into corresponding locking slots on the ends of the sidewalls. When the mandrel is fully extended, pressure is applied to the tabs on the vertically oriented middle section of the wrap using a pair of hinge-mounted pressure plates fitted with unique biased brackets. The resulting container is removed from the machine, which is then ready to begin another cycle.

Disclosed is a new machine for forming strong, durable and recyclable containers of the type described in U.S. Pat. No. 5,497,939 without the use of glue or nails which are ready to be loaded, closed, stacked and shipped. The machine utilizes a mandrel movably mounted on a path between retracted and extended positions. As the mandrel cycles forward, it first receives two synthetic sidewalls of the container to be formed, which are firmly compressed against the sides of the mandrel as it moves forward. The mandrel next encounters the body panel or wrap of the container to be formed, said wrap including a plurality of tabs along the edges of its two longer sides which correspond to locking slots on the sidewalls. As the mandrel moves forward, it pushes into the middle of the wrap whereupon a set of plows and shoes bend the upper and lower portions of the wrap into a more horizontal orientation, leaving the middle of the wrap in a vertical position. As the mandrel pushes the wrap through the machine, a set of moveable upper and lower rockers containing unique pressure mechanisms press the tabs on the horizontally oriented portion of the wrap into the locking slots on the ends of the sidewalls. When the mandrel is fully extended, pressure is applied to the tabs on the vertically oriented middle section of the wrap to form the bottom of the container using a pair of hinge-mounted pressure plates fitted with unique biased brackets.