Retractable Punch Ring Assembly for Can Chine Wrinkling
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Solution Overview
Problem
Conventional redrawing processes for beverage cans are prone to wrinkling, especially with thinner aluminum blanks and changing base configurations, due to the lack of effective tools to inhibit wrinkling during the redrawing and ironing processes.
Innovation Solution
A redraw tooling assembly that includes a punch ring supported by a compliant structure, such as a spring plate or elastomer, which contacts the chine wall of the metal cup to prevent wrinkling during redrawing and retracts during the doming process to form the dome without deforming the chine wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional redrawing tooling is used, then the redrawing process can be completed, but wrinkling occurs on the chine wall especially with thinner aluminum blanks
Solution Approach 1:
A punch ring is introduced as an intermediary component between the center punch tool and the cup wall. The punch ring contacts the chine wall during redrawing to prevent wrinkling, acting as a mediator that distributes pressure and supports the thin aluminum material without being part of the primary punch assembly
Solution Approach 2:
The punch ring is made movable relative to the center punch tool, allowing it to dynamically adjust its position during the redrawing process. The ring can move axially to maintain optimal contact with the chine wall while accommodating variations in material thickness and deformation characteristics
2Object-affected harmful factors
If a fixed punch ring is used to prevent wrinkling, then wrinkling is inhibited, but the chine wall becomes deformed with grooves or bows
Solution Approach 1:
The punch ring is designed to be movable rather than fixed, allowing it to dynamically adjust its position and contact pressure during redrawing. This dynamic capability enables the ring to prevent wrinkling while accommodating the natural deformation of the chine wall, avoiding the creation of grooves or bows that would result from fixed rigid contact
Solution Approach 2:
The contact parameters between the punch ring and chine wall are made variable through the movable design. The ring can adjust its axial position and contact force during the redrawing process, changing the interaction parameters to prevent wrinkling while maintaining chine wall geometry integrity
3Object-affected harmful factors
If the punch ring remains in position during doming, then wrinkling prevention is maintained, but the dome cannot be properly formed
Solution Approach 1:
The punch ring's movable design enables it to perform different functions at different stages of the process. During redrawing, the ring is positioned to contact and support the chine wall to prevent wrinkling. During doming, the ring can be repositioned or retracted to clear the doming path, allowing proper dome formation without interference
Solution Approach 2:
The punch ring engages in periodic action by being active during the redrawing stage and inactive during the doming stage. The ring is positioned to contact the chine wall during redrawing, then repositioned or retracted during doming, creating a periodic engagement pattern that satisfies both wrinkling prevention and dome formation requirements
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 solution effectively inhibits wrinkling during the redrawing and ironing processes, ensuring the formation of a smooth chine wall and dome in beverage cans, even with thinner materials and changing base configurations.
Implementation Method 1
The compliant support postitions the punch ring to contact the wall, preferably the angled wall, of the metal during redrawing. Later, after the wall ironing process, the compliant support can be deformed (as in spring compression or elastomer compression) when the doming tool contacts the metal to form the dome.
Data Source
Figure 1A~2
Figure 3
Figure 3A
AI summary
Redraw tooling includes a punch tool, a punch ring that is retractable relative to the punch tool, a punch sleeve, and a spring or resilient material that urges the punch ring forward. Retracting the punch ring provides support for the redraw chine to diminish wrinkling.