Can End Free Forming With Controlled Thinning
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Solution Overview
Problem
The challenge in forming metallic can ends is uncontrolled thinning, which leads to non-uniform stresses, warping, twisting, or fractures, due to aggressive material working required for high strength and lightweight materials like aluminum alloys.
Innovation Solution
A method and apparatus for forming can ends with controlled thinning, involving a forming press that cuts a can end blank, clamps the peripheral portion, and uses a pre-panel punch to form a cup with limited contact, preventing overextension and ensuring consistent geometry through a dual-action piston-controlled pre-panel punch and a lower shelf to define the final shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If aggressive material working is used to achieve high strength and lightweight can ends, then strength and weight requirements are met, but uncontrolled thinning occurs leading to non-uniform stresses, warping, twisting, or fractures
Solution Approach 1:
The method performs preliminary cupping of the can end blank before final forming operations. This preliminary action pre-shapes the material in a controlled manner, distributing stresses evenly and preventing excessive thinning during subsequent forming operations, thus maintaining both strength and dimensional consistency
Solution Approach 2:
The invention employs a dual-action piston system that dynamically controls the forming process. The first piston performs cupping while the second piston performs final forming, allowing the system to adapt to material flow requirements at different stages and maintain consistent material thickness throughout the process
2Weight of moving object
If thin materials like aluminum and aluminum alloys are used to reduce manufacturing costs and product weight, then cost and weight requirements are met, but the materials are more susceptible to uncontrolled thinning and inconsistencies during forming
Solution Approach 1:
The preliminary cupping stage prepares thin aluminum materials by gradually shaping them before final forming, preventing sudden stress concentrations that would cause thinning inconsistencies. This staged approach allows thin materials to be formed reliably while maintaining their weight advantage
Solution Approach 2:
The invention changes the forming parameters by using a two-stage process with different piston actions. The first stage uses parameters suitable for initial shaping of thin material, while the second stage uses parameters optimized for final geometry, ensuring consistent results with thin aluminum alloys
Data Source
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AI summary
A can end blank (S) is initially cupped and a central portion of the cup is rolled up with an annular portion of the cup being free formed with limited contact with any tooling except to prevent wrinkling, to prevent overextension of the free formed material and to define a final geometry of the free formed material as the forming press reaches a bottom of its forming stroke. The free forming is performed by controlling the motion of a pre-panel punch (118) using a double action piston (123) so that the pre-panel punch (118) is selectively moved between an extended position for formation of a cup of a cupped can end blank (114) and a retracted position for free forming material between a central portion of the cup (106C) and a clamped portion of the cupped can end blank (124).