초록 ▼

Method and apparatus for forming a stackable tray from a paperboard blank having a base panel, two pairs of wall panels attached to the base panel, adhesive coated gussets formed at the corners of the wall panels, and flanges formed along the outer edge of each wall panel. The tray forming apparatus

Method and apparatus for forming a stackable tray from a paperboard blank having a base panel, two pairs of wall panels attached to the base panel, adhesive coated gussets formed at the corners of the wall panels, and flanges formed along the outer edge of each wall panel. The tray forming apparatus includes a vertically reciprocating plunger having vacuum ports formed in its side walls, two pairs of flange folding fingers mounted on the plunger, a forming head including a cavity disposed beneath the plunger, and a stacking cage having flange retaining rails disposed beneath the cavity for receiving the trays after forming. The trays are formed as follows: A tray blank is first positioned over the forming cavity. The downwardly reciprocating plunger contacts the blank and urges it into the cavity causing the tray sidewalls to be erected and the adhesive coated gusset corners to be folded against adjacent side walls. The erected tray walls are retained on the plunger by the vacuum ports. The flange folding fingers are actuated by linear cams, with first one pair of flanges being folded and then the other with the flanges being folded outwardly and downwardly with respect to the tray walls into an overbroken position until the flanges lie at an acute angle to the tray walls. At the bottom limit of the travel of the plunger, the formed tray is ejected into the stacking cage which is dimensioned to retain the flanges of the trays in the overbroken position and the tray is nested in the stack of previously formed trays so as to hold the gusset corners securely against the tray walls for a time sufficient to allow the adhesive to set. The folded flanges lend stiffness to the upper edges of the tray walls and allows the trays to be nested in the stacking cage. The flanged tray can be later sealed with a lid.

대표청구항 ▼

A method of forming a tray from a paperboard blank or the like having inherent resiliency, the tray including a base panel, two pairs of wall panels attached to the base panel, panels formed at the corners of the wall panels, and flanges formed along the outer edge of each wall panel, comprising the

A method of forming a tray from a paperboard blank or the like having inherent resiliency, the tray including a base panel, two pairs of wall panels attached to the base panel, panels formed at the corners of the wall panels, and flanges formed along the outer edge of each wall panel, comprising the steps of: providing adhesive on at least one of each adjacent wall panel and corner panel; forming said tray wall panels into an erected position; folding each said corner panel to contact an adjacent wall panel such that the adhesive is in the area of contact; folding said flanges outwardly and downwardly from said erected tray wall panels into an overbroken position to lie in an acute angle with respect to said wall panels, said flanges being folded through an angle sufficient to overbreak the flanges with respect to said walls such that said folded flanges may relax to a raised, approximately horizontal position when said tray is released; retaining said flanges against the resiliency of the blank in said overbroken position over and in contact with said corner panels to retain said panels in contact with the adjacent wall panels for a time sufficient to allow an adhesive bond to form therebetween; and releasing said tray to allow upward movement of the flanges to the raised position, whereby a tray is formed with a substantially continuous horizontal flange around the periphery thereof to allow sealing of a cover to the tray.