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Theory of Operation The NDC Infrared Engineering APC System is designed to operate with automatic thermal die lip adjusting mechanisms. Expansion and
contraction of the lip adjusting unit makes possible very fine control of the die. By changing the power density level to each die bolt, the temperature is increased or decreased, thereby changing the lip opening and product
thickness. The APC System is provided with standard power level control, or optionally with temperature feedback from the die.At the end of every scan across the web, the NDC Infrared Engineering measurement system sends profile
thickness or coatweight data to the APC module. Composites of multiple profiles are processed to eliminate the effect of machine direction variation. An Adaptive Response Time Algorithm (ARTA) is utilized to determine the correct
adjustments to the die lip, and calculates the appropriate power level changes for each die bolt. The ARTA control model makes adjustments to all die bolts, simultaneously, ensuring stability of flow within the die. It can control
each scan and insures the most rapid response to profile variation without danger of over controlling the process. The control model automatically compensates for adjacent diebolt interaction, as well as nonlinear effects of
necking and shrinkage. The APC enables control to either a flat or . shaped" profile of preprogrammed design. All control parameters and configurations are selected on the touchscreen display and can be recalled via recipe
on a per product basis. |
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