Mould Base with Alternating Bosses for Plastic Container Bottom
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing plastic container manufacturing techniques face challenges in achieving sufficient mechanical strength and stability, particularly at the bottom of containers, due to inadequate molecular orientation and increased material usage or blowability issues when attempting to stiffen the bottom with radial ribs or special molds.
Innovation Solution
A mold base design featuring a concave vault with alternating first and second bosses distributed in annular bands, providing mechanical strength and aesthetic appeal while maintaining good blowability, includes a first annular part forming the seat and a second dome-shaped part forming the vault with distinct zones and projections to ensure proper material distribution and creep.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If radial ribs are added to stiffen the container bottom, then mechanical strength is improved, but material consumption increases
Solution Approach 1:
The patent applies local quality by creating a vault structure with varying thickness distribution - thicker at the center and gradually thinner toward the periphery. This localized thickness variation provides enhanced mechanical strength exactly where needed (at the bottom center under greatest stress) while minimizing additional material consumption in less critical areas, thus resolving the contradiction between strength improvement and material saving.
2Strength
If radial ribs are added to stiffen the container bottom, then mechanical strength is improved, but blowability deteriorates
Solution Approach 1:
The patent segments the bottom structure into a central vault portion and a peripheral flange portion, with the vault containing the stiffening thickness variation and the flange providing a flat sealing surface. This segmentation allows the vault to provide mechanical strength while the flange maintains good blowability by providing a compliant area that can properly fit the mold impression during the blowing process.
3Ease of manufacture
If blowing pressure is increased to improve material distribution, then blowability is improved, but energy consumption increases
Solution Approach 1:
The patent applies preliminary action by pre-heating the blank to a temperature above its glass transition temperature before the blowing operation. This preliminary thermal preparation reduces the material's viscosity and enhances its creep characteristics, allowing the material to flow and distribute more easily into the mold cavities at lower blowing pressures, thus improving blowability while reducing energy consumption.
4Strength
If the vault profile extends close to the seat, then mechanical strength is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent applies partial action by extending the vault structure only to a controlled distance from the seat rather than directly to it. The vault's thickened portion is positioned to provide maximum mechanical strength while stopping before the seat area, leaving the seat region with normal thickness for proper material distribution and mold filling. This partial extension resolves the contradiction by providing sufficient strength without compromising manufacturing precision in the critical seat area.
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 design enhances mechanical strength and stability of the container bottom, maintains good blowability, and offers an aesthetically pleasing appearance by effectively distributing forces and preventing deformation under pressure, ensuring the container's stability when filled or empty.
Implementation Method 1
the thickness of the material makes it difficult to distribute it by creep in the mold impressions corresponding to the ribs
Implementation Method 2
the double molecular orientation (axial and radial) that the material undergoes during blowing or stretch blowing
Implementation Method 3
Pushing back induces an increase in the rate of deformation of the material and therefore a mechanical increase in its crystallinity
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
The invention relates to a mold base (28) for manufacturing, from a preform made of plastic material, a container (10) comprising a body (11) extending along a longitudinal axis between an opening (121) and a base (13), the base (13) having a seat (14) forming a positioning plane (141) of the container (10), a concave vault (15) of revolution around the longitudinal axis (X), and extending from a vicinity of the seat (14) to an amorphous central zone (151), stiffening bosses (16, 17) projecting from the concave vault (15) and extending radially inside the vault (15), characterized in that said mold base (28) comprises: - a first annular part (281) intended to form at least in part the seat (14); - a second part (282) in the shape of a dome intended to come into contact with an amorphous central zone of the preform to form the vault (15) in such a way that the bosses (16,17) of stiffening are angularly spaced from each other by alternating first bosses (16) and second bosses (17) distributed according to a first annular band (19) in which the first bosses (16) extend from a first end (161) in the vicinity of the base (14) to a second end (162), the first bosses (16) providing a second annular band (20) between their second end (162) and the central amorphous zone (151), and a third annular band (21) in which the second bosses (17) extend from a first end (171) in the vicinity of the central amorphous zone (151) to a second end (172), the second bosses (17) providing a fourth annular band (22) between their second end (172) and the base (14); the second part (282) bearing: - a first annular band (283) of projections intended to form the first bosses (16) in the vicinity of the base (14),- a second annular band (284) of projections intended to form the second bosses (17) in the vicinity of the central amorphous zone (151).