Invertible Blowmolded Container Base Design
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Solution Overview
Problem
Conventional stretch blowmolding methods struggle to form container bases with sufficient rigidity, especially around deep protrusions, leading to inadequate material distribution and potential deformation during inversion, affecting the container's stability and appearance.
Innovation Solution
The method involves blowmolding a container base with invertable walls and hinges, allowing the plastic to flow into cavities instead of deep protrusions, increasing orientation and rigidity, and enabling the walls to rotate without substantial distortion, thereby enhancing the base's structural integrity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional stretch blowmolding is used with deep protrusions in the mold, then the container base can be formed, but the plastic material cannot properly flow and stretch around the protrusion due to contact friction, resulting in insufficient material distribution and inadequate base rigidity
Solution Approach 1:
The patent inverts the traditional mold design by using cavities instead of deep protrusions. The base is formed with walls that extend away from the container interior during blowmolding, then these walls are inverted toward the interior after molding. This inversion approach eliminates the friction problem of plastic flowing around deep protrusions while maintaining the desired base geometry and rigidity.
Solution Approach 2:
The patent performs the base wall inversion after the container has been blowmolded and cooled. By delaying the inversion action until after the main molding process, the plastic has already set with proper material distribution, and the subsequent inversion can be performed on a more stable structure without compromising base definition or rigidity.
2Ease of operation
If the base lacks sufficient rigidity due to inadequate material distribution, then the container can be manufactured, but the base deforms during inversion of walls, affecting the container's ability to stand stably
Solution Approach 1:
The patent applies inversion to the base wall geometry itself rather than attempting to invert walls into a poorly formed base. By forming the base with walls extending outward during molding and then inverting these pre-formed walls, the base maintains its structural integrity and rigidity throughout the inversion process, ensuring stable container composition.
3Shape
If plastic material contacts deep protrusions during blowmolding, then the base shape can be formed, but contact friction prevents proper material flow and stretching, leading to insufficient material distribution
Solution Approach 1:
The patent eliminates the friction problem by inverting the mold geometry from protrusions to cavities. The plastic flows into cavities during blowmolding, allowing unrestricted material flow and stretching. The desired base geometry is then achieved by inverting the formed walls after molding, rather than trying to form the geometry directly against protruding surfaces.
Solution Approach 2:
The patent allows the plastic to flow and distribute properly into cavity formations during the blowmolding process before the inversion operation. This preliminary proper material distribution occurs under optimal flow conditions, and the subsequent inversion simply repositions the already well-distributed material into the final base geometry.
Data Source
AI summary
A base of a container may include a standing surface, a first wall, a second wall, a first hinge, and a second hinge. The first hinge may be positioned between the standing surface and the first wall, the first wall being rotateable about the first hinge relative to a longitudinal axis of the container. The second hinge may be positioned between the first wall and the second wall, the second wall being rotateable about the second hinge relative to the longitudinal axis of the container, where rigidity of the base prevents substantial net distortion of the base during rotation of the second wall.