Stationary holddown mat for corrugator double backer

摘要

A double backer for curing the web bonding adhesive and drying the corrugated paperboard web utilizes a web holddown apparatus for maintaining the web in intimate drying contact with the lower heating units which does not require the use of a driven holddown belt. The holddown is provided instead by a series of parallel, flexible, closely spaced strips suspended above the web in the heating section and extending in the direction of web travel. Supplemental holddown force may be provided by banks of spring fingers supported above and in contact with the holddown strips on a transverse support rod which may be rotated to vary the amount of supplemental holddown force. Alternately, the holddown strips may comprise continuous cables in which one run of the cables rests upon the moving web to provide the web holddown and a second run includes high friction cable portions which are movable into driving contact with the upper surface of the web to pull it through the heating section, as for initial web thread up. An embodiment is also disclosed in which the holddown strips are tied together laterally to form a more stable mat-like holddown system.