Blow Mold Projection for Plastic Container Stability
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Solution Overview
Problem
Existing methods for producing plastic containers, particularly those designed for hot filling, face issues with deformation and reduced ground clearance due to the injection point of the preform, leading to potential tilting or wobbling of the container under pressure.
Innovation Solution
A blow mold device with a heatable base part and side parts that form a projection to press the injection point inward during expansion, combined with a gaseous medium for stability and a filling unit that heats the liquid to compensate for volume changes during hot filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the container is filled with hot medium causing pressure buildup, then the container can compensate for volume changes during cooling, but the bottom bulges reducing ground clearance and causing tilting or wobbling
Solution Approach 1:
The blow mold includes a projection that preliminarily presses the injection point inward during the expansion process, positioning it in a deeper region before hot filling occurs. This preliminary action prevents the injection point from bulging outward during subsequent pressure buildup, maintaining ground clearance and preventing tilting or wobbling during and after hot filling
Solution Approach 2:
The blow mold's inner wall is heated at least in sections, with the projection located in a central region that receives targeted heating. This localized heating ensures the injection point area has sufficient thermal stability to resist bulging under pressure, while other regions of the container maintain their required properties for hot filling
2Ease of manufacture
If the injection point is pressed into a depression in the bottom part during molding, then the container can be formed, but the injection point reduces ground clearance when the container expands under pressure
Solution Approach 1:
Instead of pressing the injection point into a depression in the bottom part (conventional approach), the invention inverts this approach by providing a projection that presses the injection point upward into the container interior during expansion. This inversion repositions the injection point to a higher location, ensuring it does not reduce ground clearance when the container expands under pressure during hot filling
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 enhances the ground clearance and stability of the container, ensuring it remains upright during hot filling by pressing the injection point inward and using heat to stabilize the container and manage pressure changes.
Implementation Method 1
the inner wall facing the plastic container being heatable or warmable at least in sections
Implementation Method 2
a filling device in order to feed a gaseous medium to the plastic preform via its mouth in order to expand the plastic preform inside the blow mold
Implementation Method 3
a rod-shaped body which is movable with respect to the blow mold in order to stretch the plastic parison during the molding process
Implementation Method 4
said projection is arranged in such a way that during an expansion process it is at least temporarily in contact with an injection point of the container
Data Source
Figure 1a~2
Figure 3a~3b
Figure 4a~6
AI summary
The invention relates to a device for moulding plastic blanks to give plastic containers with a blow mould (2), comprising a cavity (4) within which a plastic blank may be moulded to give a plastic container, wherein the blow mould (2) has a base part (6) to form a base section (10c) of the container (10), said base part defining the cavity (4), a filling device for introducing a gaseous medium into the plastic blank via the mouth thereof, in order to expand the plastic blank within the blow mould (2), with a rod-like body (15), which may be moved relative to the blow mould (2) in order to draw the plastic blank (10) during the moulding process, wherein the base part (6) has a forming section (12) defining the cavity (4), for forming the base section (10c) of the container which matches the shape of the base section (10c) of the container (10) and the forming section (18) has a projection (14) running in the direction of the cavity (4) in a central region (Z).