Patent ID: 9579684
Date: 2017-02-28
CPC Classifications: B05C,B05D

Claim:
1. A method of controlling a slot die, the slot die including: an applicator slot extending about a width of the slot die, wherein the applicator slot is in fluid communication with a fluid flow path through the slot die, a plurality of measurement instruments, each one being configured to provide a local measurement of a cross-directional thickness of the fluid flow path at the location of the respective measurement instrument; and a plurality of actuators spaced about the width of the applicator slot of the slot die, wherein each actuator in the plurality of actuators is operable to adjust the cross-directional thickness of the fluid flow path at its respective location to provide a local adjustment of fluid flow through the applicator slot, the method comprising: providing a controller in communication with each actuator and measurement instrument, wherein the controller is configured to set a position of each actuator according to one of a plurality of discrete settings, measuring, via the plurality of measurement instruments, a first die slot thickness profile including the local measurements of the cross-directional thickness of the fluid flow path at the location of the respective measurement instruments; operating the slot die by passing an extrudate through the fluid flow path and out the applicator slot with the actuators positioned according to the first die slot thickness profile; measuring, via a sensor, a cross-web thickness profile of the extrudate after it exits the applicator slot; determining, via the controller, an improved die slot thickness profile based on a fluid dynamic model of the die incorporating parameters of die dimensions and fluid rheology, the fluid dynamic model including determining the improved die slot thickness profile as a function of variables including the measured cross-web thickness profile, the preselected cross-web thickness profile, and the measured first die slot thickness profile including the local measurements of the cross-directional thickness of the fluid flow path, the improved die slot thickness profile corresponding to an improved set of discrete settings from the plurality of discrete settings, the improved set of discrete settings being configured to provide an improved cross-web thickness profile of the extrudate after it exits the applicator slot that more closely matches the preselected cross-web thickness profile; adjusting, via the controller, the location of each actuator according to the improved set of discrete settings; and continuing to operate the slot die by passing the extrudate through the fluid flow path and out the applicator slot while adjusting the actuators according to the improved set of discrete settings.