APPARATUS FOR MEASURING INNER DIAMETER OF METAL

摘要

PROBLEM TO BE SOLVED: To detect a hanging part of starting part in the inner diameter of a coil where the coil is started to be wound and measure the amount of the hanging part. SOLUTION: A rotary head 6 set in a coil 1 is provided with two press roll parts 2 to extend and contract a cylinder 5. At this time, the inner face of inner diameter of the coil is pressed by the press roll parts 2. A measuring element 13 is coupled to the rotary head 6 by a spring 19, having a front end part urged by the spring 19. A contact element 18 with a detection roll 16 is set at the front end of the measuring element 13. A wire 11 is stretched between the press roll parts 2. When the cylinder 5 is extended in the coil diameter direction, the detection roll 16 is moved by a guide pulley 15 and a pulley 14 towards the inner face of the coil by the amount of the extension of the cylinder 5. The measuring element 13 is equipped with a sensor 17. If a hanging part is present in the direction of the detection roll 16, the sensor 17 measures the amount of the hanging part at a position where the detection roll 16 butts against the hanging part. When a measured value is larger than a set value, the rotary head 6 is rotated to tighten the coil.