DETECTING METHOD FOR PRESENCE OR ABSENCE OF SPOOL IN EXPANSION TYPE TENSION REEL

PURPOSE:To prevent the buckling in coil of a strip coil by detecting the position inside a tension reel of an expand rod via a position detector and by detecting the presence or absence of a spool based on the detected value thereof. CONSTITUTION:The cylindrical face is formed by the plural reel hubs 3 having an inclined curved face 3a at the inner side and the expand rod 4 equipping with the inclined curved face 4a which abuts with sliding to the curved face 3a is arranged as well. Moreover, the rod 4 is linked with a piston 5a and a rack 6a is formed at the tip of the cylinder rod 6 thereof. The rod 4 is moved upto the stroke end in case of the spool 2 being not fitted, when the reel hub 3 is expanded via the sliding of the inclined curved face 3a, 4a. In this case, the unfitting of the spool 2 is decided with the signal of the rotation quantity of the pinion 7 which is engaged with the rack 6 being transmitted to a position detector 8 and comparison part 9. Consequently, the buckling of the strip soil can be prevented.