Metal Container Blow Molding with Shock Annealed Preforms
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Solution Overview
Problem
Impact extruded metal preforms face challenges in the pressure-ram-forming process due to high dislocation density from shear stresses, leading to work hardening and localized failure during deformation, while conventional annealing methods are inefficient and require multiple steps.
Innovation Solution
Shock annealing of impact extruded preforms using inductive heating to rapidly reach 65-98% of the melting point temperature, followed by differential shock annealing and preheating of specific regions to enhance ductility and prevent deformation, allowing for single-step expansion in pressure-ram-forming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If impact extruded preforms are used in pressure-ram-forming, then production efficiency is improved, but material failure occurs due to work hardening from high dislocation density
Solution Approach 1:
The preform is shock annealed before the pressure-ram-forming operation to reduce dislocation density and eliminate work hardening effects. This preliminary heat treatment restores material ductility, allowing the preform to successfully undergo the subsequent forming process without localized failure or cracking.
2Strength
If conventional annealing methods are used, then material ductility is improved, but process complexity increases due to multiple steps and reduced efficiency
Solution Approach 1:
Conventional mechanical or gradual thermal annealing processes are replaced with shock annealing using rapid heating methods such as induction heating, laser heating, or microwave heating. This substitution achieves the same ductility improvement in a single rapid step rather than through multiple conventional annealing operations, significantly simplifying the process.
3Loss of time
If shock annealing is applied, then energy consumption is reduced and process time is shortened, but temperature control precision must be increased to avoid grain growth
Solution Approach 1:
The annealing process uses extreme parameter values - very rapid heating rates (shock heating) combined with very short exposure times at elevated temperature. By changing the time-temperature parameters to such extreme values, the process achieves annealing in seconds rather than minutes or hours, reducing both time loss and the window for grain growth while maintaining material properties.
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
Enables the successful use of impact extruded preforms in pressure-ram-forming with reduced material failure and energy consumption, achieving complex shapes with increased ductility and deformability without grain growth or warping.
Implementation Method 1
The preform material is inductively heated to achieve a minimum temperature rise in the material of at least 120°C/sec
Implementation Method 2
pressurizing the preform to expand the preform into contact with the die cavity and impart the desired shape onto the preform
Data Source
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AI summary
A method is disclosed for pressure forming a metal preform including shock annealing of the preform and subsequently preheating the preform prior to pressure forming. Shock annealing may be carried out as differential shock annealing in which different regions of the preform are annealed to different degrees. Preheating may be carried out by differentially preheating, optionally shock preheating, different regions of the preform for preheating at least those regions of the preform which will be subject to elevated expansion during pressure forming. Shock annealing by induction heating can lower energy consumption, reduce processing times and allow for larger expansion of the preform.