Electrodeposition Coating Method for Uniform Thickness on Complex Structures
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Solution Overview
Problem
The double coating method for electrodeposition coating on complex structures like automotive bodies results in uneven coating due to temperature differences causing volume shrinkage issues, leading to recesses and uneven thickness, and prolongs the coating process duration.
Innovation Solution
An electrodeposition coating method that includes a degreasing/cleaning step using ultrasonic vibration, a chemical conversion step, and a two-step electrodeposition process with a rinse water removal/reduction step and thermal flow step to ensure uniform coating thickness and reduce process duration, using a combination of dip-rinsing and spray-rinsing, and dehumidification to prevent surface unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the first electrodeposition coating film is caused to thermally flow with rinse water partially left thereon, then the coating process can be completed, but a recess is formed at the boundary between wet and dry portions causing uneven coating thickness
Solution Approach 1:
The patent applies preliminary action by removing rinse water from the target object before the thermal flow step. This prevents the formation of recesses during thermal flow by ensuring uniform heating across the coating film surface, thereby maintaining coating thickness uniformity while still completing the coating process
2Manufacturing precision
If the double coating method is used to ensure desired thickness on inner plate portion, then coating uniformity on complex structures is improved, but the entire process duration is prolonged
Solution Approach 1:
The patent extracts the rinse water removal step from the conventional double coating process and positions it strategically before the thermal flow step. This optimization maintains the necessary two-step electrodeposition process for uniform coating on complex structures while reducing overall process duration by eliminating unnecessary time delays
3Ease of manufacture
If rinse water is not removed before thermal flow, then the process is simpler, but temperature difference causes volume shrinkage difference leading to recess formation
Solution Approach 1:
The patent applies preliminary action by removing rinse water before thermal flow to prevent the temperature difference issue. By taking this preparatory step, the process maintains simplicity while avoiding the formation of recesses that would compromise surface smoothness
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
The method achieves a uniform electrodeposition coating layer with desired thickness on both exposed and unexposed surfaces of complex structures, matching the duration of a single-step coating process while maintaining surface smoothness and appearance.
Implementation Method 1
a degreasing step of degreasing and cleaning the target object, from the surface of which the dirt or the oil and fat content has not been removed yet, through ultrasonically vibrating a degreasing solution
Implementation Method 2
a thermal flow step of allowing the first electrodeposition coating film to thermally flow after the rinse water removal/reduction step
Implementation Method 3
a first electrodeposition step of forming, in a first electrodeposition tank, the first electrodeposition coating film on the target object through application of a direct current voltage
Implementation Method 4
the portion that gets wet with the rinse water 103 slowly increases in temperature until the rinse water 103 evaporates
Data Source
AI summary
An electrodeposition coating method includes a degreasing/cleaning step, a chemical conversion step, and an electrodeposition coating layer formation step. The degreasing/cleaning step includes a degreasing step of ultrasonically vibrating a degreasing solution in which a target object is immersed, using an ultrasonic vibrator. The electrodeposition coating layer formation step includes: a first electrodeposition step; a first rinsing step; a rinse water removal/reduction step of removing or reducing rinse water on a rinse water stagnating surface of the target object; a thermal flow step of allowing the first electrodeposition coating film to thermally flow so that the first electrodeposition coating film formed on a portion of the target object near a first counter electrode has a higher electrical resistance than the first electrodeposition coating film formed on a portion of the target object far from the first counter electrode; and a second electrodeposition step.