Blow Mold Contour Deviation for Shrinkage Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing blow molding methods often result in containers with reduced volume due to material shrinkage after demolding, making it challenging to maintain a predetermined target volume and contour.
Innovation Solution
The inner contour of the blow mold is designed to deviate from the outer contour of the container in specific areas, allowing for controlled shrinkage to achieve the target contour and volume, taking into account the material's properties to minimize deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the container is blown with a target contour during the blowing pressure, then the container volume is maximized, but the material shrinkage after demolding results in volume reduction and deviation from target contour
Solution Approach 1:
The blow mold contour is pre-adjusted to compensate for the anticipated shrinkage that will occur after demolding. By intentionally creating a non-target contour during blowing that accounts for material shrinkage behavior, the final container achieves the desired target contour and volume after the shrinkage process completes.
Solution Approach 2:
The inner contour parameters of the blow mold are deliberately modified to differ from the target container contour. This parameter change in the mold geometry compensates for the material shrinkage that occurs during cooling and demolding, ensuring the final product meets the specified volume and contour requirements.
2Ease of manufacture
If the blow mold inner contour matches the target container contour, then the molding process is simplified, but the final container volume deviates from the target volume due to shrinkage
Solution Approach 1:
The blow mold is pre-configured with a compensated contour that anticipates and accounts for material shrinkage. This preliminary adjustment in mold geometry ensures that even though the mold contour differs from the target container contour, the final shrunk container achieves the precise target volume and contour specifications.
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 approach ensures that the final container maintains the specified target volume and contour with minimal deviations, effectively addressing the issue of material shrinkage during the blow molding process.
Implementation Method 1
thermal conditioning along a transport path in the region of a heating section
Implementation Method 2
expanded into a container by biaxial orientation. The expansion is achieved with the aid of compressed air, which is introduced into the preform being expanded
Implementation Method 3
The container is cooled to room temperature along a transport path after its demolding
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a method and device for blow moulding containers (2). A preform (1) consisting of a thermoplastic material is first subjected to thermal treatment along a transport path in the vicinity of a heating section (24). The preform (1) is then re-modelled by means of blow pressure inside a blow mould (4) in the container (2). The container (2) is blown with an actual contour under the action of the blow pressure, said contour deviating from a target contour of the container (2) in such a way that after removal from the mould and shrinkage the actual contour of the container (2) substantially adopts the target contour. To achieve this, the blow mould (4) has an inner contour that deviates from the target value course of the outer contour (2) of the container.