Apparatus and method for folding over an edge portion of thin sheet

摘要

This apparatus acts to fold over along a crease line an edge portion of a thin sheet of material, such as aluminum foil. On opposite sides of the crease line, the sheet includes a body portion and an edge portion, which edge portion is in-line with the body portion when the sheet is unfolded and is doubled back on the body portion when the sheet is fully folded. A pair of support rolls have spaced-apart axes and peripheries over which the sheet is caused to pass so that a region of the sheet extends between the peripheries. During the folding process the sheet is caused to travel in a direction extending from a first to a second one of the support rolls. An air film roll is positioned between the support rolls and exerts on the region of the traveling sheet between the support rolls a force that causes the body portion of the sheet in this region to be deflected toward the zone between the support roll axes. The air film roll has an outer end located at the crease line so that the edge portion folds along the crease line from the in-line position at the first support roll to a position perpendicular to the body portion at the outer end of the air film roll and then to the doubled-back position at the second support roll.