Movable Mold Bottom for Blow Molding Base Stability
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Solution Overview
Problem
The existing blow-molding techniques for manufacturing containers result in a thin bead of material on the base, which affects the stability and rigidity of the container due to operational play between the mold and mold bottom, leading to material flow issues and air evacuation problems.
Innovation Solution
A mold design with a recessed reserve and a movable mold bottom that transitions from an extended to a retracted position, creating a horizontal parting line and operational play between the wall and mold bottom, preventing material flow and ensuring correct base formation and air evacuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If operational play is provided between the mold bottom and the wall to enable movement and air evacuation, then the mold bottom can move freely and air can be evacuated, but material flows into the gap forming a bead that reduces container stability
Solution Approach 1:
The patent extracts the harmful effect (material flow into gap) by redesigning the gap location. Instead of having the gap between the mold bottom and wall, the gap is moved to the periphery between the wall and the container body, allowing air evacuation without material intrusion into the base formation zone.
Solution Approach 2:
The patent introduces a peripheral gap as an intermediary channel for air evacuation. This mediator allows trapped air to escape during blow molding without requiring a gap in the base formation area, thus preventing material flow issues while maintaining air evacuation functionality.
2Manufacturing precision
If the mold bottom is moved toward the top position corresponding to the final shape, then the container base is formed, but material pinched in the gap forms a bead that projects on the base
Solution Approach 1:
The patent removes the source of the harmful bead formation by eliminating the gap from the base formation zone. The gap is relocated to the periphery, so material is not pinched during mold bottom movement, preventing bead formation on the container base.
Solution Approach 2:
The patent relocates the gap from a vertical position (between mold bottom and wall) to a horizontal peripheral position (between wall and container body). This dimensional change allows air evacuation functionality to be maintained while removing the harmful effect of material pinching during base formation.
3Loss of substance
If the operational play is reduced to minimize material flow, then material waste is reduced, but air evacuation is impeded and malformation occurs
Solution Approach 1:
The patent introduces a peripheral gap as an intermediary air evacuation channel. This mediator provides a dedicated path for air to escape during blow molding, ensuring reliable container formation without requiring large operational play that would cause material waste.
Solution Approach 2:
The patent segments the gap function into two separate locations: a peripheral gap for air evacuation and no gap in the base formation zone to prevent material flow. This segmentation allows each function to be optimized independently, preventing material waste while ensuring air evacuation.
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 results in a container with improved stability and structural rigidity by eliminating axial projections on the base, minimizing material waste, and enhancing air evacuation, thus addressing the challenges of material flow and air entrapment in the blow-molding process.
Implementation Method 1
a mold bottom (16) that can move in relation to the wall between an extended position, in which the mold bottom is separated from the opening, and a retracted position, in which the mold bottom is fitted into the reserve
Implementation Method 2
the wall defining, beyond the cavity, a recessed reserve emptying into the cavity via the opening; the upper surface of the mold bottom defines a peripheral face that extends in the lengthening of the base surface around the latter, perpendicular to the counterbore
Implementation Method 3
a gap is provided between the mold bottom, mounted on a guide jack, and the wall, to maintain between these two parts operational play that has two purposes: on the one hand, to make possible the movement without wedging of the mold bottom in relation to the wall; on the other hand, to form a decompression air-hole making it possible to evacuate the air that is trapped between the mold and the container during blow molding
Data Source
AI summary
A mould (12) for producing, from a blank (3), a container (2) having a bottom (6) provided with a seat (8), the mould (12) including: —a wall (14) delimiting a cavity (17) and, beyond the cavity (17), a hollow recess (21) opening into the cavity (17) via an opening (20); —a mould bottom (16) that is movable relative to the wall (14), the bottom having an upper surface (27) defining a seat surface (28) having the footprint of the seat (8) of the container (2). In this mould: —the wall (14) has a counterbore (24) that defines, at the top, the hollow recess (21) and that extends perpendicular to and around the opening (20), substantially parallel to the central axis (X); —the upper surface (27) defines a peripheral face (30) that extends flush with the counterbore (24).