Apparatus for controlling web tension

Claim 1

Apparatus for unreeling a roll of web-like material from a spool containing said material to supply equipment performing a processing operation upon said web-like material, said equipment exerting a pulling force on said material, which comprises, in combination: a. a base; b. a turntable, rotatably mounted on said base, for carrying said spool containing said web-liKe material, said turntable including a circular rim extending downward from the underside of said turntable; c. a pair of diametrically opposed drag brake means, each of said drag brake means including: i. a curved drag brake shoe support mounted to said base at one end of said drag brake shoe support for rotation within the plane of said rim, said drag brake shoe support being spaced radially outwardly from said rim and extending in a concentric curve around no more than one quarter of the circumference of said rim; ii. a drag brake shoe pad mounted on said curved drag brake shoe support; and iii. drag brake actuator means for moving said curved brake shoe support to bring said drag brake shoe pad into contact with said rim; d. a pair of diametrically opposed stopping brake means, said stopping brake means and said drag brake means being positioned adjacent to one another in the same horizontal plane about the circumference of said rim, each of said stopping brake means including: i. a curved stopping brake shoe support mounted to said base at one end of said stopping brake shoe support for rotation within the plane of said rim, said stopping brake shoe support being spaced radially outwardly from said rim and extending in a concentric curve around no more than one quarter of the circumference of said rim; ii. a stopping brake shoe pad mounted on said cuved stopping brake shoe support adjacent said rim; and iii. stopping brake actuator means for moving said curved stopping brake shoe support to bring said stopping brake shoe pad into contact with said rim to thereby stop the rotation of said turntable; e. a plurality of idler rolls mounted on said base for guiding said material from said spool to said equipment; f. a dancer roll mounting arm pivotally mounted at one end on said base for rotation about an axis parallel to the axis of rotation of said turntable; g. a dancer roll attached to said mounting arm, said dancer roll being positioned intermediate two of said idler rolls to thereby form a tortuous path of travel for said web; h. biasing means connected to said mounting arm for normally rotating said mounting arm away from said idler rolls to thereby provide a known tension in said material; i. proportioning means, connected to said mounting arm and responsive to the angular position thereof, for controlling the application of said drag brake actuator means to thereby control the speed of rotation of said turntable to maintain a constant tension in said material as it is unreeled; and j. means for activating said stopping brake actuator means to thereby stop the rotation of said turntable in response to the movement of said mounting arm to its most remote location away from said idler rolls by said biasing means.