Seamless Can Bottom Coating for Reformed Grounding Portions
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Solution Overview
Problem
Existing methods for manufacturing seamless cans face challenges in reliably applying a bottom coat to the grounding portion after bottom reformation, leading to reduced conveyability and difficulty in ensuring compressive strength due to the absence of coating on this critical area.
Innovation Solution
A method involving a two-step bottom coating process is employed, where a first coating is applied before bottom reformation and a second coating is applied after, using an ultraviolet curable coating material to ensure the grounding portion is protected by a coating film, even after deformation, thereby improving conveyability and compressive strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If bottom coating is performed before bottom reformation, then the coating process is simple, but the grounding portion after reformation lacks coating
Solution Approach 1:
The coating process is divided into two separate stages: first coating before bottom reformation and second coating after bottom reformation. This segmentation ensures that each coating stage targets the grounding portion in its respective state, guaranteeing complete coverage while maintaining process simplicity.
Solution Approach 2:
The first bottom coating is applied in advance before the bottom reformation process. This preliminary coating provides initial protection and reduces friction during the reformation process, while the second coating completes the coverage on the final grounding portion.
2Reliability
If spray coating is used to coat the inner peripheral wall of the annular leg portion, then coating coverage is improved, but the process complexity increases
Solution Approach 1:
The coating operation is segmented into two simple outer surface coating processes rather than one complex spray coating operation. Each coating stage uses standard outer surface coating equipment, avoiding the need for complex spray coating apparatus while ensuring complete coverage of the grounding portion.
3Weight of moving object
If the can body is thinned for resource saving, then weight is reduced, but compressive strength decreases
Solution Approach 1:
The bottom reformation process creates a curved end with a dome portion and annular leg portion, transforming the flat bottom into a three-dimensional curved structure. This curvature distribution enhances the compressive strength of the thinned can body by dispersing stress more effectively throughout the bottom structure.
Solution Approach 2:
The combination of the curved end geometry and the bottom coating creates a composite structure where the coating layer works synergistically with the curved metal structure to enhance overall compressive strength while maintaining thin wall thickness for weight reduction.
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 ensures reliable application of the bottom coat to the grounding portion, enhancing conveyability and compressive strength of seamless cans without requiring complex positional adjustments, and simplifying the manufacturing process.
Implementation Method 1
using an ultraviolet curable coating material to ensure the grounding portion is protected by a coating film
Data Source
Figure 1
Figure 2(A)~2(C)
Figure 3
AI summary
A method for manufacturing a seamless can according to the present invention, includes molding a preform can formed with a dome portion formed at the center of a bottom portion and protruding inside the preform can and a leg portion including a grounding portion having an annular shape and formed surrounding the dome portion, performing first bottom coating of performing an outer surface coating on at least the grounding portion of the preform can, performing bottom reformation of forming a curved end having an annular shape and including a grounding portion by inserting a pressing body into the preform can coated in the first bottom coating and pressing the bottom portion of the preform can by the pressing body and a molding die installed on an outer surface side of the preform can, and performing a second bottom coating of performing an outer surface coating on at least the grounding portion of the curved end formed in the bottom reformation. The method can provide a seamless can in which a bottom-coating film is reliably applied on the grounding portion of the bottom portion.