PURPOSE: To provide a method for reproducing a paper tube for yarn winding where modification to the inner diameter to allow the paper tube to be mounted on a spindle can be made while generation of separation and peeling are not generated on the inner surface of the used paper tube.
CONSTITUTION: In reproducing a paper tube for yarn winding, a piston 3 having at least a piston part 3a of the small outer diameter which is approximately equal to the reference inner diameter DS and a piston part 3b of the lager outer diameter is inserted into the inner diameter part of the used paper tube 1 in the order of the piston part 3a of the small outer diameter and then the piston part 3b of the large outer diameter, and reciprocated along the axial direction of the used paper tube 1.
GYOTOKU HITOSHI
KAWASAKI SHUICHI