Abstract: This capacitor assembly includes inner and outer sheets of metal foil constituting first and second electrodes, respectively, of the assembly and dielectric film interposed between the foil sheets and insulating the foil sheets from each other when the capacitor assembly is energized. The foil sheets and the dielectric film are wound about a central axis to form a roll in which the sheets and the film are disposed in interleaving turns extending about the central axis in face-to-face relationship. Each of the foil sheets has a head edge near the central axis and a tail edge near the outer periphery of the roll. The head and tail edges of the inner foil sheet are folded over to reduce electric-field stress concentrations adjacent these edges. But the head and tail edges of the outer foil sheet are left unfolded, and the outer foil sheet adjacent its head and tail edges extends about the central axis substantially beyond the respective head and tail folded edges of the inner foil sheet.

Abstract: 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.