PURPOSE: To obtain an expanded plate far stable in dimensions by a method wherein, before the plate is processed by an expander, the central portion of a lead alloy sheet is continuously punched to make a lug.
CONSTITUTION: A lead alloy sheet 1 is continuously fed in a sheet punching machine 15 and the sheet is inserted into a space provided by a pair of upper and lower molds 16, 16'. The lower mold 16' is fixed, while the upper mold 16 is made movable upward and downward. Feeding of the lead alloy sheet 1 is suspended at the predetermined position and the upper mold 16 is moved downward. The unnecessary portion in the central portion of the lead alloy sheet 1, excluding a lug, is punched by a punching die 12' provided in the central portion of the upper mold 16. After a hole has been punched, either side of the lead alloy sheet 1 excluding its central portion is processed by an expander 3, so that the sheet is changed into the form of expanded meshes. The portion where the expanded meshes across each other is pressed by a pair of rollers 18 until it has the predetermined thickness.
OGUMA MIKIO
NOMURA YOUICHI
