Movable Blow Mold Base for Plastic Bottle Shaping
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Solution Overview
Problem
Existing methods for forming plastic preforms into plastic containers, particularly bottles, face challenges in effectively shaping the base regions of these containers, leading to suboptimal container quality.
Innovation Solution
A method involving a blow mold with a movable base part and a rod-like body to expand the plastic preform, where the preform is subjected to sequential pressures and the base part is advanced at specific times to enhance shaping, particularly during the application of intermediate and final blow pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a base part is placed onto the containers during the expansion process (active-base process), then the shaping of the base regions is improved, but the force requirements and pressure needs increase
Solution Approach 1:
The base part is made movable relative to the side parts of the blow mold, allowing it to be advanced toward the preform during specific phases of the blowing process. This dynamic positioning enables the base part to engage with the expanding preform at the optimal moment, improving base region shaping while controlling the forces involved through timing rather than constant engagement.
Solution Approach 2:
The base part is advanced toward the preform in a periodic manner during specific phases of the blowing process (during intermediate blow or during final blow), rather than maintaining continuous contact. This periodic engagement allows the base part to exert shaping forces only when needed, reducing overall force requirements while maintaining shaping effectiveness.
2Productivity
If higher pressure is applied to expand the preform, then the container formation is more effective, but the force requirements for base part movement increase
Solution Approach 1:
The blowing process is divided into distinct phases with different pressure levels: pre-blow phase, intermediate blow phase, and final blow phase. Each phase uses appropriately scaled pressure levels, with the base part advanced during specific phases. This segmentation allows effective container formation using lower pressures in early phases, reducing overall pressure needs while maintaining productivity.
3Manufacturing precision
If the base part is advanced during the intermediate blow phase, then the shaping control is improved, but the complexity of the process increases
Solution Approach 1:
The base part is designed to be movable relative to the side parts of the blow mold, with a drive mechanism that allows it to be advanced toward the preform during the intermediate blow phase. This dynamic capability provides superior shaping control for the base region and container body, while the movement is integrated into the existing blow mold structure, managing complexity through functional integration.
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 method improves the control over the blowing speed and wall thickness of the containers, resulting in higher container quality, reduced force requirements for base part movement, and lower pressure needs in the forming station.
Implementation Method 1
the plastic preform is subjected to a first pressure... the plastic preform is subjected to a second pressure, which differs from the first pressure and is higher than the first pressure... the plastic preform is subjected to a third pressure, which differs from the second pressure and is higher than the second pressure
Data Source
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AI summary
Method for forming plastic preforms into plastic bottles, comprising the steps of: - introducing a plastic preform (10) that is to be expanded into a blow mould, wherein this blow mould has at least two side parts (14) and a bottom part (18) which is movable in a longitudinal direction (L) of the plastic preform (10) in relation to these side parts (14); - introducing a rod-shaped body (34) through a mouth of the plastic preform (10) into the interior of the plastic preform (10); - applying a first pressure (P1) to the plastic preform (10); applying a second pressure (Pi) to the plastic preform (10), wherein this second pressure (Pi) differs from the first pressure (P1) and is preferably higher than the first pressure (P1); applying a third pressure (P2) to the plastic preform (10), wherein this third pressure (P2) differs from the second pressure (Pi) and is preferably higher than the second pressure (Pi). According to the invention, after applying the third pressure (P2) to the plastic preform (10), the bottom part (18) is moved in the longitudinal direction (L) of the plastic preform (10) towards the latter.