Thermoplastic Tube Pull-Apart Forming for Uniform-Wall Containers
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Solution Overview
Problem
Existing methods for manufacturing thermoplastic containers are limited by relative dimensions, material restrictions, and the inability to create uniform wall thickness, undercuts, and efficient labeling.
Innovation Solution
A method involving a thermoplastic tube with defined zones, locally heated and pulled apart to form tubular parts, which are then deformed into containers using blow molding, vacuum forming, or pressing, allowing for uniform thickness and undercuts without successive heating cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If deep drawing is used to manufacture containers, then the container shape can be formed, but the side walls become very thin and non-uniform thickness is achieved
Solution Approach 1:
The container manufacturing process is divided into two distinct stages: first forming the bottom and side walls through pull-apart of a thermoplastic tube, then separately inflating the container to achieve final shape. This segmentation allows the bottom to be formed with uniform thickness first, then the inflation process uniformly distributes material to create consistent wall thickness throughout, avoiding the non-uniform thinning caused by single-stage deep drawing.
Solution Approach 2:
The bottom of the container is formed in advance through the pull-apart process before the inflation step. This preliminary formation of the bottom with controlled thickness allows subsequent inflation to uniformly distribute the thermoplastic material, ensuring uniform wall thickness is achieved before final shaping, rather than relying on deep drawing to create both shape and thickness simultaneously.
2Shape
If injection moulding is used, then containers can be manufactured with complex shapes, but the entire container must be made of the same thermoplastic polymer material
Solution Approach 1:
The invention enables the use of composite materials by allowing different thermoplastic polymer materials to be used for different portions of the container. The pull-apart process can utilize a first thermoplastic for the bottom and side walls, while a second different thermoplastic can be used for the closure, achieving material versatility and functional optimization without requiring the entire container to be made of a single material as in injection moulding.
3Volume of moving object
If the container volume is increased, then larger packaging capacity is achieved, but the wall thickness must be increased proportionally
Solution Approach 1:
The invention changes the manufacturing parameters and process sequence to decouple volume from wall thickness requirements. By using the pull-apart process followed by inflation, the thermoplastic material can be distributed more efficiently throughout the container structure. The inflation process allows the container to be expanded to larger volumes while maintaining uniform, thinner wall thickness, as the material is uniformly distributed during expansion rather than requiring proportionally thicker walls to maintain structural integrity.
4Shape
If deep drawing is used, then container shape is formed, but the upper opening must be large enough to remove the press
Solution Approach 1:
The bottom and side walls are formed in advance through the pull-apart process before the inflation step. This preliminary formation allows the container structure to be established with the desired shape and dimensions, including a smaller upper opening, before the inflation process completes the shaping. The press is removed after pull-apart and before inflation, eliminating the constraint that the upper opening must be large enough to accommodate press removal.
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 larger container dimensions with thin walls, flexible material choices, and direct ink-printing, while avoiding costly molds and reducing material waste.
Implementation Method 1
c) locally heating said middle zone to the thermoforming temperature of the thermoplastic
Implementation Method 2
d) pulling said first zone and said second zone apart along said longitudinal direction thereby narrowing the middle zone
Implementation Method 3
said deforming preferably comprising at least one of: blow moulding, vacuum forming and pressing
Implementation Method 4
said deforming preferably comprising at least one of: blow moulding, vacuum forming and pressing
Data Source
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AI summary
A method for manufacturing a thermoplastic container. The method comprises locally heating a middle zone of a thermoplastic tube; gripping the tube on either side by using retaining members; pulling the tube apart, causing a middle zone to narrow; pushing the inner wall of the middle zone against each other to obtain a closure; and cutting through the closed-off middle zone to obtain two separate tubular parts. The container is formed by: blow moulding or vacuum forming or pressing a tubular part; or arranging a bottom moulding member and deforming a bottom portion by pressing a bottom moulding member and a retaining member against each other; or by vacuum moulding the bottom portion. This combination of steps makes it possible to make containers over a whole variety of relative and absolute dimensions and with fewer limitations in the choice of thermoplastic materials.