Deep Draw Closure Cap Ironing for Wall Thickness Control
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Solution Overview
Problem
Deep draw closure cap production faces challenges in minimizing material usage while maintaining functional requirements, such as conforming to bottle threads, and in preserving coatings like lacquer coatings during the forming process, which often results in non-uniform thickness and waste due to excessive mechanical working.
Innovation Solution
A method involving draw forming and redrawing a cup, followed by an ironing die process that reduces the thickness of the cup wall adjacent the open end, allowing for substantial material savings without compromising functionality and coating integrity, by differentiating between functional and non-functional sections of the cap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional draw-redraw processes are used to form deep draw closure caps, then the desired dimensions of wall height and wall thickness can be obtained, but substantial material working is required which results in non-uniform thickness, earing, scuffing, and coating damage
Solution Approach 1:
The patent changes the forming parameters by using a single-stage deep draw process with specifically controlled punch force, die geometry, and material flow characteristics to achieve the desired wall height and thickness without multiple redraw operations. This single-stage process maintains more uniform wall thickness and reduces material working compared to traditional multi-stage draw-redraw processes
Solution Approach 2:
The patent applies preliminary coating to the blank material before the deep draw forming process, ensuring the coating is in place before any mechanical working occurs. This preliminary coating application protects the material surface throughout the forming process and eliminates the need for post-forming coating restoration
2Reliability
If coatings are applied before the draw-redraw process to provide corrosion protection, then corrosion protection is achieved, but the coatings often become damaged during the forming process requiring reapplication
Solution Approach 1:
The patent applies the coating to the blank material before the deep draw forming process, allowing the coating to be in place during the entire forming operation. The single-stage forming process with controlled parameters minimizes coating stress and damage, making reapplication unnecessary and maintaining continuous corrosion protection throughout production
Solution Approach 2:
The patent modifies the forming parameters including punch speed, die pressure, and material flow control to reduce mechanical stress on the pre-applied coating. These parameter changes allow the coating to remain intact throughout the forming process, eliminating downtime for coating reapplication
3Reliability
If substantial material thickness is used to ensure cap functionality and conforming to bottle threads, then reliable functionality is achieved, but material usage increases significantly
Solution Approach 1:
The patent creates local quality variations in the formed cap wall thickness through controlled material flow during the single-stage deep draw process. The forming parameters are optimized to provide adequate thickness in functional areas (such as the thread engagement zone) while allowing thinner sections in non-critical areas, thereby maintaining cap functionality while reducing overall material usage
Solution Approach 2:
The patent uses precisely controlled forming parameters including punch force distribution, die cavity geometry, and material flow restrictions to achieve optimal wall thickness distribution. These parameter changes enable the cap to maintain sufficient thickness for functional requirements while minimizing excess material consumption throughout the structure
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
This method achieves significant material savings and maintains coating integrity by reducing the thickness of the non-functional section of the cap, ensuring reliable functionality and reduced waste, while minimizing the impact on lacquer coatings.
Implementation Method 1
As the material passes through the successive dies, the thickness of the material defining the wall tends to increase as it passes over the die
Implementation Method 2
As the material is drawn through the die, the material toward the outer end is compressed to form the diameter of the wall
Data Source
Figure 1
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Figure 2A
AI summary
A method for forming a deep draw closure cap, the method comprising: - draw forming a first cup from a planar sheet of metal material defining a base thickness, the first cup including a first cup base, a first cup wall, and an open end; - performing a first redrawing of the first cup to form a redrawn cup having a redrawn cup base and a redrawn cup wall, and an open end, the first redrawing; - further passing the material through an ironing die, wherein the ironing die reduces the thickness of the redrawn cup wall at least adjacent the open end.