Stretch Blow Molding Head Cooling via Internal Rinsing Fluid
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing stretch blow molding processes require complex designs to cool the head section of containers to prevent the memory effect, which involves slow and inefficient external cooling due to high material thickness.
Innovation Solution
The inner wall of the container's head region is cooled using a rinsing fluid supplied through fluid outlets on a stretching bar, allowing for efficient cooling from the inside.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the head section is cooled from the outside using conventional blow mold cooling, then the material orientation is maintained to prevent memory effect, but the cooling process is slow and energy-consuming due to high material thickness
Solution Approach 1:
Instead of cooling the head section from the outside through the blow mold walls, the invention introduces cooling fluid through the stretching rod that extends into the container interior. The cooling fluid is supplied via channels in the stretching rod, allowing direct cooling of the head section from the inside where the material thickness is greatest, thereby dramatically improving cooling speed and reducing energy consumption
Solution Approach 2:
The stretching rod serves as an intermediary cooling device, containing internal channels that transport cooling fluid directly to the head section interior. This intermediary structure enables efficient heat transfer from the hottest region (head section) without requiring complex external cooling systems
2Reliability
If the blow mold is designed with external cooling systems for the head section, then the memory effect is prevented, but the blow mold design becomes relatively complex
Solution Approach 1:
The stretching rod is given multiple functions: it performs the stretching operation during blow molding and simultaneously serves as a cooling device through its internal fluid channels. This multi-functionality eliminates the need for separate external cooling systems in the blow mold, simplifying the overall design while maintaining reliable memory effect prevention
Solution Approach 2:
The cooling function is extracted from the blow mold structure itself and transferred to the stretching rod. By removing the cooling system from the complex blow mold assembly and placing it in the simpler stretching rod, the blow mold design is simplified while the cooling function remains effective
3Productivity
If compressed air is used as blowing fluid, then the container is formed efficiently, but additional cooling measures are required to prevent memory effect in the head region
Solution Approach 1:
The forming process using compressed air and the cooling process are merged into a single integrated system. The stretching rod that delivers the compressed air for forming also contains channels for cooling fluid, allowing both operations to occur simultaneously through the same component, thereby maintaining high productivity without adding separate cooling system complexity
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 effectively prevents the memory effect by ensuring rapid and energy-efficient cooling of the container head area, reducing material deformation and simplifying the blow mold design.
Implementation Method 1
the inner wall of the container is supplied with a rinsing fluid from the at least one fluid outlet of the pull-up bar, at least for cooling a head area
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for blow molding containers (5) in a stretch blow molding machine, wherein a container (5) designed as a preform is inserted into a blow mold (1) and subsequently, during the blow molding process, stretched within the container (5) by moving a stretching bar (9) having at least one fluid outlet (12) along the container axis, and the container (5) is formed by applying a blowing fluid. According to the invention, after the container (5) has been formed, the inner wall of the container (5) is supplied with a rinsing fluid from the at least one fluid outlet (12) of the stretching bar (9), at least for cooling a head region (16).