Measuring diameter of roll of web material for use with gluing machine - times free end of rotating reel of web, as it passes predetermined position on successive rotations, to calculate diameter of reel.

摘要

A method for measuring the diameter [D] of a reel [L] of wound web material [N] includes rotating the reel on two supporting rollers [3,5] rotating in the same direction. The free end [Lf] of the material is lifted from the reel passes over a vacuum box [11] where its position is detected by an optical sensor [13]. This sensor enables the time period between two successive passes of the free end of the web through a predetermined position on the vacuum box to be measured. The diameter of the reel is then determined from this time period and the peripheral speed of the reel, calculated from the angular rotation and radius of the supporting rollers.