Open loop heating controller and method for corrugators

In a corrugating machine for the production of double-face corrugated paperboard by joining a flat paper web to one side of a corrugated medium to form a single-face web and joining a second flat paper web to the opposite side of the corrugated medium to form the double-face corrugated paperboard, apparatus for heating the webs as a function of only one production factor of the corrugator machine and without a feedback signal comprising:

• at least one rotatably journaled heating roll for receiving a web in contact with a circumferential area of the roll;
• means positionable relative to the heating roll for varying the circumferential area of contact between the web and the roll;
• and,
• control circuit means for positioning the positionable means relative to the heating roll in response to only one production factor of the corrugating machine, said control circuit means comprising:
• means for sensing said one production factor of the machine and for generating a signal related to said sensed production factor;
• means for periodically sampling said generated production factor related signal;
• means for storing the sampled production factor related signal at a first time;
• means for comparing said stored production factor related signal with said production factor related signal sampled at a time subsequent to said first time;
• means responsive to said comparing means for generating a drive signal related in value to a difference between the compared signals;
• and,
• drive means for driving the positionable means in response to said generated drive signal.