Deep-Inset Base Plastic Container Mold Inversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The reheat stretch blow molding process struggles to manufacture plastic containers with a deep inset base, often resulting in extreme stretching, thinning, crimping, or folding of the container wall in the base area, making it difficult to produce containers with a deep inset base effectively.
Innovation Solution
A plastic container design featuring a main body with a deep inset recess defined by an upstanding inner sidewall and an outer sidewall, where the upstanding sidewall is substantially straight and parallel to the outer sidewall, along with a method involving a mold assembly that inverts a base projection portion to form a deep inset base during the reheat stretch blow molding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the reheat stretch blow molding process is used to manufacture containers with a deep inset base, then the container can have improved stackability and space utilization, but the container wall experiences extreme stretching and thinning leading to crimping and folding deformities
Solution Approach 1:
The preform is designed with a pre-formed base projection portion that defines the future deep inset base geometry. This preliminary shaping allows the deep inset base to be formed with controlled material distribution during the blow molding process, preventing extreme stretching and wall thinning that would otherwise occur when trying to create deep bases from conventional preforms.
Solution Approach 2:
The invention modifies the preform geometry by incorporating a base projection portion with specific dimensional parameters (height, diameter, curvature) that optimize material flow during blow molding. By carefully controlling these parameters, the process achieves deep inset bases without causing wall thinning or deformities, as the preform parameters are tailored to match the final container geometry requirements.
2Ease of manufacture
If conventional preform designs are used in reheat stretch blow molding, then the manufacturing process is simple, but it is practically impossible to effectively manufacture containers with deep inset bases without deformities
Solution Approach 1:
The preform is segmented into distinct functional portions: a body portion, a base projection portion, and a standing ring portion. This segmentation allows each portion to be optimized independently for its specific function while maintaining overall manufacturing simplicity. The base projection portion can be designed with specific geometry to achieve deep inset bases without complicating the overall molding process.
Solution Approach 2:
Instead of trying to create a deep inset base by stretching material inward during blow molding (which causes deformities), the invention inverts the approach by pre-forming a base projection that extends outward. During blow molding, this projection is inverted into the final deep inset base shape, achieving the desired geometry while maintaining wall integrity and process simplicity.
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 approach allows for the successful formation of containers with a deep inset base, minimizing material costs and preventing unwanted deformities, while enabling optimal material distribution and stackability.
Implementation Method 1
The preform is first heated and then is longitudinally stretched and subsequently inflated within a mold cavity
Implementation Method 2
The preform is first heated and then is longitudinally stretched and subsequently inflated within a mold cavity
Implementation Method 3
The preform is first heated and then is longitudinally stretched and subsequently inflated within a mold cavity
Implementation Method 4
The polymer solidifies after contacting the cooler surface of the mold
Data Source
AI summary
A plastic container of the type that may be formed from a material such as PET using the stretch blow molding process includes a main body portion and a base portion that is characterized by a relatively tall and narrow profile above the standing ring and that has a deep inset recess defined therein. The deep inset recess is defined in part by an upstanding inner sidewall portion adjacent to the standing ring that has a height that may be greater than about 0.35 inch. The upstanding inner sidewall portion may have a substantially straight portion that is substantially parallel to a substantially straight portion of an outer sidewall of the base.