Mould Bottom Design for Thermoplastic Container Blow Moulding
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Solution Overview
Problem
The manufacturing of thermoplastic containers, particularly bottles, faces challenges in achieving sufficient mechanical strength and uniform shaping of the bottom, which is exacerbated by the complex shape and high blowing pressures required, leading to inefficiencies in material distribution and cooling within the mold, resulting in lower quality products and increased energy costs.
Innovation Solution
A mold base design with radiating branches featuring an inclined upper part with multiple points of curvature and a concave transition zone between the trunk and base support facilitates the even distribution and descent of hot amorphous material, improving material flow and internal rigidity, allowing for reduced blowing pressures and increased production rates while maintaining mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high blowing pressure (40×10^5 Pa) is used to achieve correct bottom deformation, then the mechanical strength and shaping quality of the container bottom is improved, but the equipment cost and electrical energy consumption increase significantly
Solution Approach 1:
The mold bottom is segmented into multiple functional zones: a central depression zone to concentrate and redirect material flow, radial grooves to guide material distribution, and a raised peripheral zone to control final bottom formation. This segmentation allows material to flow more efficiently under reduced pressure while maintaining shaping quality.
Solution Approach 2:
The mold bottom geometry is pre-configured with depression zones and radial grooves that actively guide and concentrate material flow before the blowing process begins. This preliminary structural arrangement ensures that material is directed to the correct locations during blowing, enabling quality formation at lower pressures.
2Manufacturing precision
If high blowing pressure is applied to achieve correct bottom deformation, then the material distribution and cooling quality improve, but the production rate cannot be increased
Solution Approach 1:
The mold bottom is divided into a central depression zone, radial grooves, and peripheral raised zones. This segmentation creates controlled flow paths that distribute material evenly and enhance cooling efficiency, allowing faster cycle times without sacrificing quality.
Solution Approach 2:
The central depression zone and curved radial grooves create smooth, continuous flow paths that reduce material resistance and improve flow dynamics. The curved geometry promotes uniform material distribution and enhances contact with cooling surfaces, enabling faster production while maintaining quality.
3Shape
If the material undergoes a large angular path (up to 90° or more) during deformation, then the bottom shape complexity is achieved, but the material plating on the mold wall becomes insufficient and cooling quality deteriorates
Solution Approach 1:
The mold bottom is pre-configured with a central depression zone and radial grooves that guide material flow along optimized paths. This preliminary structural arrangement reduces the angular deviation during deformation while ensuring material reaches all necessary areas for proper plating and cooling.
Solution Approach 2:
The curved radial grooves and depression zones create smooth transition paths that reduce sharp angular changes in material flow. This curved geometry maintains better material contact with the mold wall throughout the deformation process, improving plating quality while achieving the required bottom shape.
4Shape
If the material undergoes a large angular path during deformation, then the inverted conical bottom shape is formed, but the deformation time increases
Solution Approach 1:
The mold bottom is segmented into a central depression zone, radial grooves, and peripheral zones. This segmentation creates multiple controlled flow paths that reduce the total angular deviation required for material to reach the periphery, thereby reducing deformation time while maintaining the inverted conical shape.
Solution Approach 2:
The curved geometry of the depression zone and radial grooves provides smoother flow paths that reduce material resistance during deformation. This allows the material to achieve the required angular displacement more quickly, reducing deformation time while forming the correct inverted conical 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
This design enhances the formation of a thicker, more solid container bottom by ensuring uniform material distribution and cooling, reducing energy consumption and production costs while maintaining mechanical integrity, thus addressing the inefficiencies of prior mold designs.
Implementation Method 1
improve the diffusion and the descent, by flow, of the amorphous material from the bottom of the blown preform
Implementation Method 2
descent of hot amorphous material
Implementation Method 3
poor cooling of the material against the mould
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a bottom of a mould (13) for a mould for producing containers, especially bottles, by blow moulding or blow drawing, said containers having a body and a bottom (14) of a container, comprising a peripheral base (15) in the shape of a crown, which is connected on the inside to a central area (16) forming an arch consisting of a plurality of radiating impressions (17) alternating with a plurality of radiating projections which are distributed in an angular and equidistant manner about a central axis (Y) of the bottom (14) of the container. For the moulding of the central area (16) of the bottom (14) of the container, the bottom (13) of the mould comprises: a plurality of radiating projecting branches (19) distributed in an angular and equidistant manner, and extending approximatively radially to the axis (X) of the bottom of the mould; a central core (20) comprising a lateral wall (21) to which the branches (19) are connected; and in-between sections (22) forming cores of angular sectors regularly separating said branches from each other. The bottom (13) of the mould is characterised in that each radiating projecting branch (19) has an upper part (23) in the form of an inclined platform which descends from the centre towards the periphery with at least two points (24, 25) of inflection of the curve.