Patent ID: 8256074

Claim:
A method of producing a grid for a battery plate comprising: providing a rotary expander for forming a large number of zigzag slits in a metal sheet 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 said circumferential face is formed, in a whole periphery of a peripheral edge of a disk, said reference circumferential face being centered at an 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 disk faces in which said valleys that are adjacent to each other via a ridge are formed in an oppositely reverse manner, wherein: in each of said disk cutters, an inclined face is formed in each of said peripheral side faces which extend from apexes of ridges formed on both sides of each of said valleys to said valley, said inclined face more approaching the axis as being nearer to said one of said disk faces in which said groove of said valley is formed; and passing said metal sheet between said two or more opposed disk cutter rolls.