Control system for macro adjustment of a polymeric melt forming slot type die

A system for adjusting a gap in a slot die for producing a polymeric web, the system comprising:

• a slot die comprising a polymer inlet and a melt outlet, a polymer reservoir extending between the polymer inlet and the melt outlet, a polymer melt within the polymer reservoir begins to solidify into a partially formed polymeric melt as it exits the melt outlet, the melt outlet having a first edge extending longitudinally along the melt outlet and a second edge extending longitudinally along the melt outlet and being opposite the first edge, the second edge being selectively moveable along a plurality of positions along a length of the second edge, the first edge being spaced apart from the second edge by a gap having an adjustable profile extending between a first end and a second end of the slot die;
• a plurality of actuators secured to the slot die at an anchor frame, the plurality of actuators being configured to move a portion of the second edge relative to the first edge to adjust the profile of the gap;
• a pressure sensor in communication with the reservoir, the pressure sensor being configured to measure pressure of the polymer melt in the reservoir;
• a measuring device that measures at least one of a thickness and a mass of the partially formed polymeric melt exiting the slot die proximate to the melt outlet;
• and
• a control unit in communication with the pressure sensor and the measuring device, the control unit having a first algorithm and an automatic profile control algorithm, the first algorithm comprising software configured with a set of polymer pressure flow rate empirical data correlating the profile of the gap to the pressure in the reservoir, the first algorithm being configured to generate a control signal to the automatic profile control algorithm in response to the pressure measured by the pressure sensor and the automatic profile control algorithm comprising software configured to generate actuator control signals to each of the plurality of actuators to adjust the profile of the gap in response to at least one of the thickness and mass of the formed polymeric melt measured by the measuring device,
• wherein the control unit utilizes the first algorithm prior to operation of the system and during a startup period of the system and the control unit utilizes at least one of the first algorithm and the automatic profile control algorithm during a steady state operation period of the system.