CLERICAL PUNCHER Russian patent published in 1997 - IPC

FIELD: office work at keeping records, filing, typing letters, etc. SUBSTANCE: clerical puncher has base with matrices and uprights, spring-loaded punches and limit stops for orientation of edges of sheets being treated. Movable cross-piece is positioned above base, in which punches are fixed. Uprights are made in the form of sleeves and rods secured on cross-piece with one ends, and with ends, for movement in sleeves. Working ends of punches facing matrix are cone-shaped and chamfered at radius of 0.05 to 0.1 mm. Angle at vertex of cone makes up 32 to 36 deg. EFFECT: reduced punching force and enhanced reliability and durability of punches; information located at punched holes can be restored and read after smoothing of sheet. 3 dwg