Patent ID: 8256075

Claim:
A method of producing a grid for a battery plate comprising: providing a rotary expander having two or more opposed disk cutter rolls, each of said disk cutter rolls having: a plurality of disk cutters on a same shaft with forming a gap therebetween, each of said disk cutters being configured by: alternately forming ridges in which a peripheral side face protrudes toward an outer periphery from a reference circumferential face of a predetermined radius, and valleys in which a peripheral side face composed of a face substantially extending along the reference circumferential face is formed, in a whole periphery of a peripheral edge of a disk, the reference circumferential face being centered at a rotation axis of said disk; and, for each of said valleys, forming a groove which is opened in a peripheral side face of said valley, in a peripheral edge portion of one of the disk faces in which valleys that are adjacent to each other via a ridge are formed in an oppositely reverse manner, wherein: among said disk cutter rolls, a disk cutter roll which is opposed to a disk cutter roll having a disk cutter that is disposed outermost is provided an endmost disk cutter that is placed more outward than said outermost disk cutter, an entire peripheral side face of said endmost disk cutter is configured by the reference circumferential face, valleys are provided on the peripheral side face of the endmost disk cutter at regular intervals, the valleys including a first set of valleys and a second set of valleys which are alternately arranged with respect to each other, each valley of the first set of valleys being an endmost node forming valley which corresponds to a valley in a disk cutter of another disk cutter roll that is opposed via said metal sheet, a peripheral side face which is recessed toward a center with respect to said reference circumferential face is formed in each valley of the first set of valleys, and an outermost diameter of the endmost disk cutter when measured between valleys of the second set of valleys is substantially equal to the diameter of the endmost disk cutter when measured at the peripheral side face of the endmost disk cutter configured by the reference circumferential face; and passing said metal sheet between said two or more opposed disk cutter rolls.