Seamless Can Body Corner Radius for Flatness
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Solution Overview
Problem
The existing seamless can bodies face issues with center panel flatness and pressure resistance due to non-uniform tensile loads during forming, leading to potential cracks and damage to the resin film, especially when made with thin-walled materials and subjected to internal pressure tests.
Innovation Solution
A seamless can body design with a radius of curvature between 1.5 mm and 6.0 mm for the corner portion between the annular concave and center panel, along with specific depth and curvature ranges for the annular concave portion, ensures uniform tensile loads and maintains high flatness and pressure resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the radius of curvature of the corner portion is made small (0.5 mm to 1.5 mm) to reduce can bottom thickness, then the can body can be made thin-walled, but the tensile load becomes non-uniform causing center panel flatness impairment and increased crack risk
Solution Approach 1:
The patent applies local quality by specifying different radius of curvature values for different regions of the corner portion. The corner portion has a radius of 0.5-1.5mm while the annular concave portion has a larger radius of 1.5-6.0mm, creating locally optimized stress distribution that maintains both thin-walled construction and center panel flatness
Solution Approach 2:
The patent changes the geometric parameters of the corner portion and annular concave portion to optimize performance. By setting specific radius ranges (corner: 0.5-1.5mm, annular concave: 1.5-6.0mm) and depth parameters (0.5-3.0mm), the design achieves uniform tensile load distribution while maintaining thin wall thickness
2Loss of substance
If the radius of curvature of the corner portion is made small to achieve thin-walled construction, then material usage is reduced, but the resin film may be damaged causing content deterioration and corrosion
Solution Approach 1:
The patent applies local quality by creating a larger radius annular concave portion (1.5-6.0mm) that serves as a stress relief zone, protecting the resin film in the corner portion from excessive tensile loads while maintaining overall thin-walled construction and material efficiency
3Loss of substance
If the tensile load during forming is made non-uniform to accommodate small corner radius, then thin-walled construction is enabled, but the flatness of the center panel is impaired reducing suitability for internal pressure tests
Solution Approach 1:
The patent changes the geometric parameters by introducing a larger radius annular concave portion (1.5-6.0mm) that redistributes tensile loads uniformly during forming, enabling thin-walled construction while maintaining center panel flatness within ±0.15mm for accurate internal pressure testing
Data Source
Figure 1~3
AI summary
A seamless can body configured so that, even if the wall thickness of the can body is small, the flatness of a center panel of a bottom of the can body can be stably maintained and the can body has high pressure resistance, high formability, and excellent properties for an internal pressure test. The seamless can body have a can bottom shape provide with: a rim portion protruding to an outside of the can; an annular concave portion adjacent to an inner side of the rim portion and protruding to an inside of the can; and a flat center panel extending continuously from an inner peripheral side of the annular concave portion with a corner portion interposed therebetween. The curvature radius (R3) of the corner section is in the range of 1.5 mm < R3 ≤ 6. 0 mm, the depth of the annular concave section is from 1.5mm to less than 3.0 mm, and the flatness (BSD) of the center panel is from -0.15 to 0.15mm.