Slot Die Actuator Control for Thickness Uniformity Without Ringing
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Solution Overview
Problem
Existing slot die systems experience undesirable 'ringing' phenomena due to neighboring actuators moving in opposite directions, leading to actuator force and bend limits, which hinder coating uniformity and efficiency.
Innovation Solution
Implement a ringing constraint in the controller to penalize actuator movements causing ringing, allowing for a revised set of actuator positions that reduce ringing while accepting small deviations in slot gap accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If neighboring actuators move in opposite directions to adjust slot height at one location, then slot height adjustment is achieved, but ringing occurs causing actuators to reach force and bend limits
Solution Approach 1:
The system changes the control parameters by introducing a ringing constraint that limits the magnitude of actuator movements. By modifying the control algorithm to penalize large actuator displacements and enforce smooth transitions, the system achieves slot height adjustment while preventing actuators from reaching their force and bend limits, thus maintaining operational reliability.
Solution Approach 2:
The system implements feedback control by continuously monitoring the slot height profile and actuator positions. The controller uses this feedback to adjust actuator commands in real-time, preventing ringing by detecting when actuators are approaching their limits and modifying their movement accordingly, thereby maintaining both precision and reliability.
2Reliability
If actuator movements are constrained to reduce ringing, then actuator reliability is improved, but slot gap accuracy may deviate
Solution Approach 1:
The system modifies control parameters by introducing a ringing constraint that allows small deviations in slot gap accuracy in exchange for significantly improved actuator reliability. The constraint penalizes actuator movements that would cause ringing, accepting minor accuracy trade-offs to prevent actuators from reaching their operational limits.
Solution Approach 2:
The system applies partial action by not achieving perfect slot gap accuracy but instead achieving sufficient accuracy that balances actuator reliability. The control algorithm accepts approximate solutions where actuator movements are constrained to reduce ringing, rather than pursuing maximum precision that would cause excessive actuator stress.
3Manufacturing precision
If multiple actuators are adjusted independently to achieve desired thickness profile, then coating uniformity is improved, but ringing causes actuators to reach force and bend limits
Solution Approach 1:
The system changes the control parameters by introducing a ringing constraint that limits actuator movement magnitudes. This allows the system to achieve coating thickness uniformity through coordinated actuator adjustments while preventing individual actuators from reaching their force and bend limits, thus maintaining operational reliability.
Solution Approach 2:
The system implements dynamic control by continuously adjusting actuator positions based on real-time feedback from thickness measurements. The controller dynamically modifies actuator commands to achieve the desired thickness profile while enforcing smooth transitions that prevent ringing and keep actuators within their operational ranges.
Data Source
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Figure 3
Figure 4A~4B
AI summary
Provided are methods of adjusting a slot die. The slot die includes an applicator slot extending along a width of the slot die, wherein the applicator slot is in fluid communication with a fluid flow path through the slot die, at least one of a group consisting of: a choker bar and flexible die lip, and a plurality of actuators spaced along the width of the slot die, each actuator operatively coupled to the choker bar or flexible die lip to adjust a slot or choker bar height profile at its respective location to provide a local adjustment of fluid flow through the applicator slot. The method includes: measuring thickness values of an extrudate provided from the applicator slot; mapping the measured thickness values to a corresponding position along the width of the slot die; executing a data compression of the measured thickness values to obtain a residual vector representing deviation of the measured thickness values from desired thickness values; and adjusting a position of one or more of the plurality of actuators based on the residual vector to obtain a corrected shape for the choker bar or flexible die lip. The adjustment includes using the residual vector to predict a degree of ringing for a proposed set of actuator positions and then applying a ringing constraint to obtain a revised set of actuator positions that reduces the degree of ringing relative to the predicted degree of ringing.