Sheet hole punching apparatus

A sheet hole-punching device comprising:

• a plurality of punch members, each punch member having a leading end with a hole-punching blade;
• a base frame for slidably supporting the punch members in a hole-punching direction and rotationally supporting the punch members;
• a drive member having a plurality of cam portions, each of said cam portions engaging each of the punch members to move the punch members in the hole-punching direction;
• and
• a plurality of cam devices, each of the cam devices being disposed between the base frame and each of the punch members for converting a hole-punching direction movement of the punch member into a rotational movement so as to rotate the punch member while moving in the hole-punching direction;
• wherein the leading ends of the punch members are respectively disposed on the base frame with a phase difference at a home position such that the punch members sequentially punch holes with a time difference to reduce a load applied to the drive member,
• wherein each of the cam devices comprises a cam groove attached to the base frame, and a shaft attached to the punch member and engaging the cam groove, and
• wherein the cam groove includes a vertical section vertically extending in the hole-punching direction and an inclined section extending from the vertical section to incline at a predetermined angle to the hole-punching direction so that by cooperation of the cam groove and the shaft engaging the cam groove, the punch member moves vertically in the vertical section without rotation thereof, and moves vertically in the hole-punching direction and rotates around an axis thereof in the inclined section.