Adjustable ballast system for a double facer

A system for selectively varying the vertical ballast load applied to an upper surface of a moving corrugated paperboard web traveling over a plurality of heating units positioned in the direction of web movement in a double facer, said system comprising:

• a plurality of rows of web engaging ballast members, each row extending over the heating units, and said plurality of rows positioned in parallel side-by-side relation transversely across the web;
• a vertical actuator for at least some segments of a row which segments overlie a heating unit, said actuator operable to move each said segment between a lower full load ballast position and an upper no load position;
• a support structure overlying the heating units;
• each row including a continuous flexible membrane;
• a series of membrane support members spaced along the membrane and defining the segments of the row;
• the upstream end of said membrane attached to said support structure;
• and,
• each of said actuators mounted on said support structure and including a vertically positionable link operatively connected to a membrane support member.

A method for controlling heat applied to a moist web of corrugated paperboard traveling over a series of individually operable heating plates supporting a lower web face of said corrugated paperboard and beneath a ballast load system in contact with an upper web face of said paperboard, said method comprising the steps of:

• (1) forming a grid pattern of ballast load member segments defining parallel rows extending over the length of the heating plates and parallel tiers, each tier extending transversely of the direction of web movement across the width of the web and generally overlying a heating plate;
• (2) mounting said load member segments on vertical actuators operative to independently move each segment between an upper no load position and a lower full ballast load position independently of any other segment and without altering the load imposed by any other segment on the corrugated paperboard web;
• (3) monitoring the moisture content of the corrugated web to detect variations in moisture content transversely across the web;
• and,
• (4) selectively operating the actuators to vary the ballast load applied in selected rows in response to the monitored moisture content.

A system for selectively varying the vertical ballast load applied to an upper surface of a moving corrugated paperboard web traveling over a plurality of heating units, which units are positioned in the direction of web movement in a double facer, said system comprising:

• a plurality of rows of ballast members, each row extending over the heating units and the web, said plurality of rows positioned in parallel side-by-side relation transversely across the web;
• each row including a plurality of segments, each segment overlying a heating unit and having a length approximately equal to the length of a heating unit;
• a vertical actuator for each of said segments, said actuator operable to move each said segment between a lower full load ballast position and an upper no load position independently of any other segment and without altering the load imposed by any other segment on the web;
• means for monitoring the temperature of the web transversely across the web;
• and,
• control means for selectively operating the actuators to vary the ballast load in response to monitored temperature.