Abstract: A multiple-winding pipe forming device for forming a wound pipe, the multiple-winding pipe forming device comprising: a plurality of pairs of forming rollers curling a metal sheet and winding the metal sheet into a roll shape; and a mandrel fabricated of metal, the mandrel including: a shaft disposed inside the metal sheet wound in the roll shape, one end side of the shaft being retained, which one end side is disposed upstream in a feeding direction of the metal sheet, and a working portion including a taper portion that increases in diameter from upstream to downstream in the feeding direction, wherein the taper portion is disposed at a position at which the metal sheet wound in the roll shape is sandwiched by, of the plurality of pairs of forming rollers, a pair of the forming rollers that is disposed at a downstream side in the feeding direction.

Abstract: An electrode plate of a storage battery includes a rectangular, conducting, porous base plate 12 and a paste 13 containing an active substance, spread over the surfaces of the base plate 12, and filled in the hollow spaces in the base plate by rolling so as to form layers attached to the surfaces of the base plate 12. When shaping the base plate 12, the corners C of the base plate 12 are rounded, and the edge of at least one of the sides S of the base plate 11 is rounded in cross section. Thus, burrs at the corners C and along the sides S are removed so that the exertion of excessive contact pressure on the corners C and the sides S of the base plate is prevented in the assembled state of the storage battery, whereby the occurrence of short circuit is also prevented.