Method of processing metal plate member of disc cartridge

摘要

A magnetic disc is housed for rotation in a flat casing having the metal shell. The magnetic disc is supported for rotation in the casing by a tubular shaft formed by barring of a metal blank for forming the metal shell. A hole is formed in a part of the metal blank where the tubular shaft is to be formed. A plurality of slits are formed prior to barring in the part where the tubular shaft is to be formed.