Deep Draw Closure Cap Wall Ironing for Material Savings
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Solution Overview
Problem
Deep draw closure caps, such as pilfer proof caps, require substantial material thickness to ensure functionality, leading to increased material usage and potential damage to coatings during the forming process, while also resulting in non-uniform thickness and waste due to mechanical working.
Innovation Solution
A method involving draw forming and redrawing of metal sheets followed by a wall ironing process to reduce the thickness of the cup wall adjacent the open end, allowing for material savings without compromising functionality, and maintaining coating integrity by reducing the thickness in non-functional sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If substantial material thickness is used to ensure functionality of deep draw closure caps, then reliability is improved, but material usage increases and cost increases
Solution Approach 1:
The cap is designed with non-uniform wall thickness, where the wall thickness varies along the axial direction. The upper portion (skirt portion) has reduced thickness compared to the lower portion (thread portion), allowing material reduction in non-critical areas while maintaining sufficient thickness in functional areas for reliability
Solution Approach 2:
The ironing process applies partial action by selectively reducing wall thickness only in the upper non-functional portion of the cap, while leaving the lower functional portion with adequate thickness. This partial material reduction achieves cost savings without compromising the cap's sealing and threading functions
2Reliability
If substantial material thickness is used to ensure functionality of deep draw closure caps, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The cap is designed with non-uniform wall thickness, where the wall thickness varies along the axial direction. The upper portion (skirt portion) has reduced thickness compared to the lower portion (thread portion), allowing material reduction in non-critical areas while maintaining sufficient thickness in functional areas for reliability
Solution Approach 2:
The ironing process applies partial action by selectively reducing wall thickness only in the upper non-functional portion of the cap, while leaving the lower functional portion with adequate thickness. This partial material reduction achieves cost savings without compromising the cap's sealing and threading functions
3Manufacturing precision
If material is subjected to elevated pressures during draw forming, then desired dimensions are achieved, but coating integrity deteriorates and waste increases
Solution Approach 1:
The ironing process is performed after the draw forming step, when the cap geometry is already established. This preliminary formation of the final shape followed by controlled ironing reduces the need for excessive pressure during the initial forming, thereby protecting the coating while achieving the desired dimensions
Solution Approach 2:
The process parameters are changed by introducing a controlled ironing step with specific pressure and temperature conditions that differ from the draw forming step. This allows the material to be worked into the final shape with reduced coating damage compared to applying all pressure during the initial draw forming
4Manufacturing precision
If multiple draw-redraw steps are used to achieve desired wall height, then manufacturing precision is improved, but material thickness becomes non-uniform and waste increases
Solution Approach 1:
The ironing process introduces controlled plastic deformation with specific pressure and temperature parameters that redistribute the material thickness uniformly along the wall. This parameter change from the draw-redraw steps corrects the non-uniform thickness profile while maintaining the desired wall height and overall geometry
Solution Approach 2:
The non-uniform material thickness and directional grain orientation created by the draw-redraw steps are converted into a benefit through the ironing process. The ironing redistributes this material uniformly, transforming the defect of non-uniform thickness into a uniform, controlled thickness profile that meets manufacturing specifications
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 method achieves significant material savings by reducing the thickness of non-functional sections of deep draw closure caps while maintaining the integrity of coatings and ensuring reliable functionality, with minimal additional processing steps and reduced waste.
Implementation Method 1
the material is passed through an ironing die, wherein the ironing die reduces the thickness of the redrawn cup wall
Data Source
AI summary
A method for forming a deep draw closure cap includes draw forming a first cup from a planar sheet of a metal material defining a base thickness. The first cup comprises a first cup base, a first cup wall, and an open end. A first redrawing of the first cup is performed to form a first redrawn cup including a first redrawn cup base, a first redrawn cup wall, and an open end. The first redrawn cup is passed through an ironing die to reduce a thickness of the first redrawn cup wall adjacent to the open end.