Coating Apparatus Base Material Height Changing Device
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Solution Overview
Problem
Existing methods for forming coating films on both surfaces of a battery electrode plate using slit dies face issues with non-uniform coating thickness due to varying discharge pressures and instability in the coating gap, leading to poor linearity at the terminal ends of the coated portions.
Innovation Solution
A coating method that involves switching the supply of a coating liquid to a slit die on and off while temporarily expanding the distance between the base material and the discharge port, using compressed gas to control the position and displacement of the base material, ensuring uniform thickness and improved linearity of the coating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If coating liquid is intermittently supplied to form coating films on opposite surfaces of base material using slit dies, then productivity is improved by simultaneous coating, but coating thickness uniformity deteriorates due to different discharge pressures affecting base material position
Solution Approach 1:
A backup roll is introduced as an intermediary support between the slit dies and the base material. The backup roll provides a stable reference surface that prevents the base material from being displaced by discharge pressure variations, thereby maintaining uniform coating thickness while allowing simultaneous coating of both surfaces
Solution Approach 2:
The backup roll acts as a counterbalancing support that opposes the disruptive effect of discharge pressure on the base material position. By providing upward support force, it counteracts the downward pressure from the slit dies, stabilizing the coating gap and ensuring uniform coating thickness
2Adaptability or versatility
If coating liquid supply is stopped to form uncoated portions, then pattern formation is enabled, but coating gap stability deteriorates due to base material being drawn into the slit die by surface tension
Solution Approach 1:
The base material position is stabilized by the backup roll before coating liquid supply is stopped. This preliminary positioning prevents the base material from being drawn into the slit die by surface tension when coating stops, maintaining coating gap stability and terminal end linearity while enabling pattern formation
3Ease of manufacture
If slit dies are positioned vertically above the base material for coating, then coating film formation is simplified, but base material position stability deteriorates due to discharge pressure variations
Solution Approach 1:
The backup roll serves as an intermediary support that maintains base material position stability while allowing the slit dies to remain in a simple vertical configuration. This intermediary support prevents position variations caused by discharge pressure without complicating the overall coating process setup
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves improved linearity and uniformity of the coating film at the terminal ends, enhancing the manufacturing efficiency and quality of battery electrode plates by stabilizing the coating gap and preventing liquid shortage failures.
Implementation Method 1
a base material height changing device configured to selectively eject compressed gas onto a lower surface of the base material
Implementation Method 2
the base material is easy to be drawn to a side of the slit die by a surface tension when a coating liquid is pulled into the slit die
Data Source
AI summary
A coating apparatus includes a transport roll for transporting a base material, a slit die facing a lower surface of the base material, a coating liquid supply controller for switching on and/or off in supply of a coating liquid to the slit die, and a base material height changing device for ejecting compressed gas onto the lower surface of the base material during a specific period from a termination of the supply of the coating liquid to the slit die to a restart of the supply of the coating liquid to the slit die.