Mold Base Raised Land for Blow Molding Stability
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Solution Overview
Problem
Existing blow-molding techniques face challenges in achieving both structural rigidity and stability in container bases, particularly due to operational play between the mold bottom and wall, leading to material flow issues and air evacuation problems, which result in flawed bases and reduced container quality.
Innovation Solution
A mold design with a movable mold bottom that transitions from an extended to a retracted position, creating a raised edge and offset land to prevent material pinching and air entrapment, allowing for proper base formation and stability without compromising air evacuation or requiring precise guiding mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a gap is provided between the mold bottom and wall to allow movement and air evacuation, then air evacuation is enabled, but material flows into the gap forming a thin bead that compromises container stability
Solution Approach 1:
The invention introduces a radial dimension solution by providing a radial offset between the mold bottom opening and the wall opening. This offset creates a annular land area that prevents material from flowing into the gap while maintaining the necessary gap for air evacuation. The radial offset transforms the one-dimensional gap problem into a two-dimensional solution space, allowing both air evacuation and material containment to coexist.
Solution Approach 2:
The invention applies local quality by creating a specific geometric configuration (annular land area with radial offset) at the critical interface between the mold bottom and wall. This localized geometric modification provides the necessary material containment function only where needed, without affecting the overall gap structure required for air evacuation. The land area is specifically positioned to intercept material flow while the gap remains open for air evacuation.
2Shape
If the mold bottom is moved to an upper position to form the final container shape, then the container shape is achieved, but material that flowed into the gap during lower position forms a detrimental bead on the base
Solution Approach 1:
The invention applies preliminary action by creating the annular land area with radial offset before the blow molding process begins. This pre-configured geometric feature is built into the mold bottom structure, ensuring that material flow is prevented from the outset during the entire forming process. The land area is already in place to intercept material before it can flow into the gap, eliminating the need for post-process corrections.
3Manufacturing precision
If a stationary wall with impression is used to define container shape, then manufacturing precision is improved, but the gap between mold bottom and wall creates material pinching and air entrapment issues
Solution Approach 1:
The invention segments the mold bottom opening into two distinct functional zones: an inner opening area that maintains the gap for air evacuation, and an outer annular land area that prevents material flow. This segmentation allows the mold bottom to simultaneously fulfill both air evacuation and material containment functions without compromising the stationary wall's precision for defining container shape.
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 ensures a base with enhanced stability and rigidity, minimizing flaws and improving container quality by preventing material pinching and facilitating air evacuation, while allowing for less precise guiding mechanisms and maintaining aesthetic appeal.
Implementation Method 1
a mold bottom (17) that can move in relation to the wall (15) between an extended position, in which the mold bottom (17) is separated from the opening (21), and a retracted position, in which the mold bottom (17) blocks the opening (21)
Implementation Method 2
the blow molding of the blank is carried out by injecting a gas (such as air) therein under high pressure (in general more than 20 bar)
Implementation Method 3
the structural rigidity of the container can be increased thermally by means of a heat-setting (in English, heat set) of the material, consisting in keeping the container in contact with the heated wall of the mold, which increases the crystallinity of the material
Data Source
AI summary
Disclosed is a mold for the manufacture, from a blank, of a container having a body and a base provided with a peripheral seat. The mold includes: a wall bearing the impression of the body of the container and provided with an opening; a mold base which is movable relative to the wall between an extended position and a retracted position; the mold base having a peripheral surface which corresponds to a join between the seat and the base of the container and terminates in an edge which is raised with respect to the seat surface. In the extended position of the mold base, the edge extends vertically perpendicular to the opening and, in the retracted position of the mold base, the edge extends near the opening.