Impact-Extruded Preform With Thickened Rim Transition Wall
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Solution Overview
Problem
Conventional impact extruded preforms with constant tubular wall thickness face challenges in pressure expansion due to uneven material thickness, leading to weak annular regions and potential container failure under internal pressure, especially in aerosol containers.
Innovation Solution
A method and tooling for impact extruding preforms with variable sidewall thickness, including a transition wall thickness to strengthen the rim section, which is formed during the impact extrusion process by redirecting and ironing the metal billet to create a thicker transition wall between the closed end and sidewall, enhancing the preform's pressure resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional impact extrusion produces preforms with constant tubular wall thickness, then the manufacturing process is simple, but the preform has weak annular regions that lead to container failure under internal pressure
Solution Approach 1:
The patent applies local quality by creating variable wall thickness in the preform, with a thicker transition wall section at the rim region and thinner sections elsewhere. This is achieved through a multi-stage extrusion process where the punch geometry and extrusion parameters are specifically designed to deposit more material in the transition zone, strengthening the rim section to withstand internal pressure without requiring the entire preform to have uniform high thickness.
2Reliability
If the transition wall thickness is increased to strengthen the rim section, then pressure resistance is improved, but material usage increases
Solution Approach 1:
The invention strengthens only the specific rim region where pressure resistance is needed by creating a thicker transition wall, while maintaining thinner wall sections in other areas of the preform. This localized thickening approach provides the necessary structural reinforcement at the critical rim zone without unnecessarily increasing material consumption throughout the entire preform.
Solution Approach 2:
The extrusion process is designed to preliminarily shape the metal billet with variable thickness distribution before the preform undergoes expansion forming. The punch geometry and extrusion parameters are configured in advance to create the thicker transition wall section, so that when the preform is subsequently expanded, the rim region already has the necessary material distribution for pressure resistance.
3Productivity
If variable thickness preforms are produced through impact extrusion, then additional shaping processes are eliminated, but the extrusion process becomes more complex
Solution Approach 1:
The patent merges the variable thickness shaping operation into the primary impact extrusion process itself. By designing the punch with specific geometric features and configuring the extrusion parameters appropriately, the variable wall thickness profile is created during the initial forming operation, eliminating the need for separate ironing or shaping processes that would otherwise be required to achieve the desired preform geometry.
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 preforms with variable thickness exhibit improved pressure resistance and reduced risk of container failure, allowing for the use in higher-pressure applications like aerosol containers without the need for additional shaping processes, while maintaining economical material usage.
Implementation Method 1
A punch driven into the die by the force of the press causes the metal blank to flow (extrude) into the die shape and around the punch
Implementation Method 2
the metal is transformed into a plastic state in which the metal will actually flow
Implementation Method 3
A punch driven into the die by the force of the press causes the metal blank to flow (extrude) into the die shape
Data Source
AI summary
A hollow preform impact extruded from a metal billet to produce a progressing wall at a transition wall thickness. An axially forward portion of the progressing wall is ironed by extrusion past an extrusion point to form a sidewall portion of a lesser thickness. Extruding is stopped while some of the billet remains to form the closed bottom end. The preform has a bottom portion, a sidewall portion and a transition wall portion extending between the bottom portion and the sidewall portion. The transition wall portion is thicker than the sidewall portion and can be formed into at least part of the rim of an expansion shaped container. An impact extrusion punch has a central axis, an axially forward, impact surface for impacting metal to be extruded, a transition region for directing material displaced by the impact surface and a rear extrusion point for ironing material extruded past the transition region.