Seamless Can Bottom Structure for Thin-Wall Pressure Resistance
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Solution Overview
Problem
Conventional seamless can body manufacturing methods face challenges such as blacking and agglutination issues during bottom reforming, limitations in thinning sheet thickness for weight reduction, and inefficiencies in pressure resistance optimization, leading to increased costs and environmental impact.
Innovation Solution
A seamless can body design with a tubular body section and can bottom section featuring specific thickness gradients and structural elements, including an outer circumferential bottom section, annular grounding section, and rising section, which allows for reduced sheet thickness while enhancing pressure resistance and eliminating the need for lubricants and subsequent cleaning steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bottom reforming is performed by pressing the inner circumferential wall with a molding roller, then pressure resistance is improved, but blacking and agglutination occur at the pressed part
Solution Approach 1:
The patent replaces the conventional molding roller pressing method with a punch pressing method. Instead of using a rotating molding roller that contacts the inner circumferential wall, a punch is used to press the inner circumferential wall from the inside in a single direction, substituting the mechanical rolling action with a direct pressing action that avoids blacking and agglutination
Solution Approach 2:
The patent introduces a lubricant as an intermediary substance between the punch and the inner circumferential wall during the pressing process. This lubricant prevents direct metal-to-metal contact, thereby eliminating blacking and agglutination while still enabling effective pressing to improve pressure resistance
2Strength
If bottom reforming is performed with pressing, then pressure resistance is enhanced, but lubricant application and cleaning steps are required
Solution Approach 1:
The patent extracts and eliminates the cleaning step from the manufacturing process. By using a punch pressing method with lubricant, the process avoids the need for subsequent cleaning operations that were required with the molding roller method, thereby simplifying the overall process
Solution Approach 2:
The punch pressing method with lubricant is designed to be self-cleaning in nature. The lubricant allows the punch to press the inner circumferential wall without adhering to it, and the pressed part does not require additional cleaning steps, making the process self-sufficient
3Weight of moving object
If the raw sheet thickness is reduced for weight reduction, then weight is reduced, but pressure resistance becomes insufficient
Solution Approach 1:
The patent applies local quality by creating a localized thickened section at the bottom of the can body through the punch pressing process. While the overall sheet thickness is reduced for weight reduction, the pressed area at the bottom has increased thickness and enhanced structural properties, providing localized strength enhancement where pressure resistance is most needed
Solution Approach 2:
The patent performs preliminary action by pre-thickening the bottom section during the forming process itself. The punch pressing is performed as part of the can body manufacturing process, creating the thickened section before the can is put into service, thereby ensuring pressure resistance is built-in from the start
4Strength
If conventional bottom reforming is performed, then pressure resistance is improved, but sheet thickness distribution is not optimized
Solution Approach 1:
The patent applies parameter changes by controlling the pressing force, punch geometry, and pressing depth to achieve a specific sheet thickness distribution. The parameters are optimized so that the inner circumferential wall is pressed to create a gradual thickness transition, with the thickest section at the bottom transitioning to thinner sections upward, optimizing both pressure resistance and material distribution
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 design enables a seamless can body with improved pressure resistance and reduced material usage, lowering production and transportation costs, and minimizing environmental impact by allowing for thinner raw sheet thickness and eliminating the need for lubricant application and cleaning.
Implementation Method 1
a first molding step of molding a raw metal material into a cup body
Implementation Method 2
a second molding step of applying a pressing force to the cup dome section... to apply compressive stresses in a meridian direction and a circumferential direction, and then pressing the inclined section into the lower molding member while a thickness of the inclined section is increased
Data Source
AI summary
[object] To provide a seamless can body in which the sheet thickness of a raw sheet (blank) is reduced, pressure resistance of a can bottom is enhanced, buckling is restrained, and problems with blacking and cleaning are solved, and a manufacturing method of the seamless can body.[Solving Means] A seamless can body 1 having a tubular body section 10 and a can bottom section 20. The can bottom section 20 includes an outer circumferential bottom section 202a extending from a lower end of the tubular body section 10 such as to decrease in diameter toward the inside and an annular grounding section 202E positioned further inside than the outer circumferential bottom section 202a. In a case where t1 is the sheet thickness of the outer circumferential bottom section 202a and where t2 is the sheet thickness of the annular grounding section 202b, the relation of t2>t1 is satisfied.