Importance

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Abstract

An envelope blank is conveyed by a transport system in an envelope making machine to a folding mechanism that folds one or more flaps of the blank. In folding a side flap, the leading edge of the blank adjacent to the score line is conveyed along a convex face of a plowshare. The plowshare face applies at the leading edge of the blank adjacent to the score line a force which bends the side flap through an angle of 180.degree. to a position where the flap is folded to overlap the blank. A crease is formed on the score line to permanently set the flap on the blank. The folding of the flap is initiated by the convex face of the plowshare. Extending from the upper edge of the plowshare face is a grid-like network of flexible rods mounted to follow the helical path of the plowshare face. The free edge portion of the flap is supported by the grid to follow the flap leading edge being folded by the plowshare. The flap folding forces are applied at the region of the flap adjacent to the score line where the flap has the least resistance to bending. The folding forces are removed from the flap free edge which is supported by the grid to follow the movement of the flap leading edge. The trailing edge of the flap is stabilized by a guide plate positioned oppositely of the plowshare in the feed path. The guide plate prevents the flap trailing edge from falling downwardly ahead of the flap leading edge to assure that the fold is maintained in alignment with the score line.

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First Claim