Friction shaft for slitter

A friction shaft for a slitter that is configured such that winding pipes for rolling unit materials, which are formed by cutting a raw material such as various kinds of paper, fabric, or film with predetermined intervals, are disposed on an outer surface thereof and that is configured to achieve both strong clamping and wide-range variable torque using one air pressure supply channel, the friction shaft comprising:

• a rotary shaft (100) having an air supply channel (110) formed at a center therein to be supplied with compressed air in a longitudinal direction;
• and
• several friction cores (200) disposed on the rotary shaft (100) to be able to rotate at positions thereof,
• wherein several air supply holes (120) connected to the air supply channel (110) are formed circumferentially on an outer surface of the rotary shaft (100) so that compressed air in the friction cores (200) can be supplied, and
• the friction cores (200) each include:
• a core pipe (210) having a through-hole (211) formed at the center thereof to be fitted on the rotary shaft (100), an insertion groove (212) formed in a ring shape at a center on an inner surface thereof to face the air supply hole (120), and exposure holes (214) circumferentially formed on an outer surface thereof and connected to the insertion groove (212) and connection holes (213);
• bearings (220) disposed at both sides of the through-hole (211);
• sealing rings (230) disposed between the insertion groove (212) and the pair of bearings (220), respectively;
• a cylindrical tube (240) configured to cover and finish the insertion groove (212) between the pair of sealing rings (230), and configured to be expanded by compressed air that is supplied from the air supply hole (120);
• clamping lugs (250) disposed in the insertion groove (212), the connection holes (213), and the exposure holes (214) and configured to be partially protruded from the exposure holes (214) by expansion of the tube (240) to come in close contact with a winding pipe;
• and elastic members (260) disposed between the insertion groove (212) and the clamping lugs (250) to partially insert the clamping lugs (250) back into the exposure holes (214) when supply of the compressed air is stopped.