Method and apparatus for making corrugated board

Claim 1

A corrugator comprising A. a single facer, B. means for conducting liner web to the single facer, C. means for conducting corrugating medium web to the single facer, said single facer fluting the corrugating medium web and laminating said web to produce single face web having a fluted face, D. a double backer, E. means for conducting the single face web to the double backer, said conducting means including a web accumulator located between the single facer and the double backer, said accumulator comprising (1) one or more stationary rollers, (2) one or more dancer rollers, said single face web being looped back and forth between said stationary dancer rollers so that the fluted face of said single face web engages around at least some of said rollers, (3) means defining a track for the dancer rollers so that the dancer rollers can move toward or away from the stationary rollers, (4) means for force loading the dancer rollers along said track away from the stationary rollers so that the single face web being conducted from the single facer to the double backer is maintained under low and substantially constant tension across its full width thereby imparting a low and substantially uniform pressure to the flutes in the single face web, (5) means for controlling the speed of the single facer or the double backer in response to the positions of the dancer rollers with respect to a reference position to allow control over either the amount of material or the amount of time the material spends between the single face and the double back processes, independent of the overall process speed and F. means for conducting liner webs to the double backer for laminating with the single face web conducted thereto so as to produce corrugated board having minimum warpage and substantially uniform crush strength along its length and breadth.