Retort Container Double Seam With Shear-Oriented Thermal Fusion
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Solution Overview
Problem
Traditional retort containers made of metal are costly and lack aesthetic appeal, while attempts to reduce metal usage in retort containers have not effectively addressed the challenge of maintaining seam integrity under high pressure and temperature conditions during retort processing.
Innovation Solution
A retort container with a thermoplastic body and metal ends, where the metal end has a central portion and peripheral portion with heat-sealable materials that form a seam with the thermoplastic body, creating a chuck wall interface oriented for predominantly shear stress, enhancing blow-off resistance during retort processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional metal containers are used for retort processing, then seam integrity is maintained under high pressure and temperature, but cost increases and aesthetic appeal deteriorates
Solution Approach 1:
The invention uses a composite construction with a thermoplastic container body and metal ends, combining the advantages of both materials. The thermoplastic body provides cost-effectiveness and aesthetic appeal, while the metal ends maintain structural integrity. The heat-sealable material creates a reliable bond between the thermoplastic and metal components, achieving seam integrity comparable to all-metal constructions without the associated costs and aesthetic limitations.
Solution Approach 2:
The invention changes the material parameters of the container body from metal to thermoplastic, fundamentally altering the construction approach. This parameter change enables the use of heat-sealable materials that can be thermally fused to metal ends, creating a new bonding mechanism that maintains reliability while reducing cost and improving appearance.
2Ease of manufacture
If metal usage is reduced in retort containers, then cost decreases and aesthetic appeal improves, but seam integrity under high pressure and temperature deteriorates
Solution Approach 1:
The composite construction allows reduced metal usage (only in ends rather than entire body) while maintaining seam integrity through the thermal fusion of heat-sealable materials. The thermoplastic body provides sufficient structural support when properly bonded to metal ends, achieving both cost reduction and reliability maintenance.
Solution Approach 2:
The invention replaces traditional mechanical seaming methods (double-seaming) with thermal fusion of heat-sealable materials. This substitution creates a reliable bond that maintains seam integrity under retort conditions while enabling the use of thermoplastic bodies with metal ends, thereby reducing overall metal usage.
3Ease of manufacture
If thermoplastic body is used instead of metal, then cost decreases and aesthetic appeal improves, but blow-off resistance during retort processing deteriorates
Solution Approach 1:
The composite construction with thermoplastic body and metal ends provides optimal performance by combining the cost-effectiveness and aesthetic appeal of thermoplastic with the strength and blow-off resistance of metal. The thermal fusion bonding ensures efficient stress transfer, allowing the thermoplastic body to withstand retort processing pressures.
Solution Approach 2:
The invention changes the material parameters to use thermoplastic with specific heat-sealable properties, enabling thermal fusion bonding that maintains blow-off resistance. The heat-sealable material creates a strong interface that prevents blow-off during retort processing while allowing the use of cost-effective thermoplastic bodies.
4Strength
If heat-sealable material interface is oriented for shear stress, then blow-off resistance improves, but manufacturing complexity increases
Solution Approach 1:
The invention optimizes the interface orientation parameter to align with shear stress directions during retort processing. This parameter change maximizes blow-off resistance by ensuring the heat-sealable material bond is oriented to withstand the primary stress forces, while the manufacturing process remains integrated into existing thermal fusion equipment.
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 solution significantly improves the container's ability to withstand internal pressure during retort processing, reducing the risk of seam failure and allowing the thermoplastic body to expand radially without permanent deformation, thus offering a cost-effective and aesthetically appealing alternative to traditional metal containers.
Implementation Method 1
heating the first heat-sealable material to a temperature sufficient to cause the first heat-sealable material to be softened or melted and to wet the radially outer surface of the chuck wall and the inner surface of the side wall
Implementation Method 2
the container body is radially unconstrained such that the container body is allowed to expand radially as internal pressure is exerted on the side wall
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A retort container includes a metal end (30) applied and sealed to an all-thermoplastic container body (22) by a crimp-seaming or double-seaming operation. The metal end has an outer curl (36) joined to a chuck wall (38) that extends down from the curl. One or both of the inner surface of the container side wall (24) and the outer surface of the chuck wall has/have a heat-sealable material (44) thereon. The metal end is crimp-seamed or double-seamed to the container body and the heat-sealable material(s) are heated to soften or melt such that the interface between the chuck wall and the side wall is fused. The interface is oriented along a direction relative to internal pressure exerted on the metal end such that stress on the interface caused by the internal pressure is predominantly shear stress.