Seamless Can Bottom Geometry for Thin-Wall Pressure Resistance
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Solution Overview
Problem
Existing seamless can bodies face limitations in reducing plate thickness while maintaining pressure resistance, particularly due to the constraints of bottom reforming techniques which thin the metallic blank material at pressed parts.
Innovation Solution
A seamless can body design featuring a raised bottom section with specific area and volume ratios, achieved through a two-step forming process that includes forming a tubular body section and a raised bottom section with controlled dimensions to enhance pressure resistance while minimizing material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bottom reforming is conducted by pressing the inner peripheral wall with a forming roller, then pressure resistance is improved, but the metallic blank material is extended and thinned at the pressed part
Solution Approach 1:
Instead of pressing the inner peripheral wall to form a recess (conventional bottom reforming), this invention forms a convex raised bottom section by inverting the forming approach. The raised bottom section is formed by controlling the drawing and ironing process to create a convex shape that extends toward the opening section, thereby improving pressure resistance without thinning the material at pressed parts.
Solution Approach 2:
The invention changes the geometric parameters of the bottom section by defining specific relationships between the outer surface area of the raised bottom section (AD) and the area of the virtual plane (AB), where 1.55 ≥ (AD/AB) ≥ 1.40. This parameter control ensures optimal pressure resistance while managing material thickness distribution throughout the forming process.
2Weight of moving object
If the plate thickness of the blank sheet is reduced to achieve weight reduction, then weight is reduced, but the pressure resistance strength is compromised
Solution Approach 1:
The invention applies local quality by creating a raised bottom section with specific geometric characteristics (outer surface area AD and virtual plane area AB relationship) that concentrates structural strength where needed. This localized geometric modification allows the use of thinner blank sheets overall while maintaining pressure resistance through the strategically designed raised section.
Solution Approach 2:
The raised bottom section incorporates curved surfaces and spherical elements (as seen in the dome section with radius rD) that distribute stress more effectively than flat surfaces. This curvature allows thinner material to achieve the same or better pressure resistance by reducing stress concentration points.
3Strength
If a raised bottom section with larger outer surface area is formed, then pressure resistance is enhanced, but material usage increases
Solution Approach 1:
The invention applies partial action by forming a raised bottom section with controlled dimensions rather than uniformly thickening the entire bottom. The specific area ratio constraint (1.55 ≥ (AD/AB) ≥ 1.40) ensures that the raised section provides sufficient pressure resistance while limiting the additional material consumption to only the necessary extent.
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 proposed solution enables the production of seamless can bodies with excellent pressure resistance and reduced material usage, effectively addressing the challenge of weight reduction while maintaining structural integrity.
Implementation Method 1
a first forming step of forming a metallic blank material into a cup body having a tubular body section, a peripheral bottom section continuing from a lower end of the tubular body section, and a bulging section bulging from the peripheral bottom section toward an opening section by a first height
Data Source
AI summary
A method for producing the seamless can body includes forming a metallic blank material into a cup body having a tubular body section, a peripheral bottom section continuing from a lower end of the tubular body section, and a bulging section bulging from the peripheral bottom section toward an opening section by a first height, and pressing down the bulging section such that the bulging section has a second height smaller than the first height, to thereby form a peripheral ground section continuing from the lower end of the tubular body section and a raised bottom section continuing from the peripheral ground section toward a center-axis side. When an outer surface area of the raised bottom section is denoted by AD and an area of a virtual plane an outline of which is defined by the peripheral ground section is denoted by AB, 1.55≥(AD/AB)≥1.40.