Applications for Narrow-Band Draw Control Differentials

Precise Speed Control of Draw-Roll in a Constant Tension Infeed on a Web-Fed Offset Printing Press:

In order to print high quality multicolor products, the web (paper from unwind stand) tension must be accurately controlled in the print units.  The constant tension infeed controls web tension by increasing or decreasing the speed of a "draw-roll" a small amount relative to the synchronous speed of the machine.

The DLA Draw-Control Differential drives the draw-roll and provides the small variable speed range required.  Input (1) to the DLA system drives the primary input of the differential as well as the input shaft of the H-Drive Mechanical Speed Variator at a constant speed.

The output of the variator drives the secondary input (3) of the differential over a large speed range - 280 to 1,675 rpm.  This variable speed input is reduced by the ratio (1 / 1 - p) or 67.85.  The result is a narrow-band of variable speed - 990 to 1,010 rpm at the output shaft (2) of the DLA, which in turn drives the draw-roll.  Speeds within this range can be set in very small increments (0.01%) and once they are set will hold nearly as well as fixed gearing (+/- 0.005% deviation).   Therefore, the web tension value is accurately set and precisely held by the DLA Narrow-Band Draw-Control Differential.

Furthermore, this closed loop mechanical system maintains the same percent speed gain at any machine operating speed.

To insure proper selection, please consult the factory.  If you have any questions regarding the information provided here or require more information, please call us at (800) 713-6170 or e-mail us. Our Sales and Engineering departments are ready to help you with your specific power transmission needs.