Stretch Rod Hydroforming for Precise Container Shaping
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Solution Overview
Problem
Existing hydro forming methods require complex modifications to machines and molds to achieve precise pressure control for shaping containers with intricate designs, such as embossed letters or small radii of curvature, leading to inefficiencies and increased costs.
Innovation Solution
A method using a piston member, such as a stretch rod, to increase pressure inside the preform by forming a closed volume with the liquid, allowing for precise control of pressure peaks without additional machinery, enabling the formation of containers with complex shapes without modifying existing equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a second pressure greater than the first pressure is applied to create a pressure peak inside the preform, then the shaping precision of the container is improved, but the device complexity increases due to requiring two sealing mechanisms with actuators
Solution Approach 1:
The stretch rod is designed to perform multiple functions: it serves as both the stretching means for axial expansion of the preform and the pressure peak application means by acting as a piston member. This multi-functionality eliminates the need for separate compression means and reduces the number of sealing mechanisms required, directly resolving the contradiction between shaping precision and device complexity
Solution Approach 2:
The invention merges the stretching function and pressure peak application function into a single integrated system. The stretch rod combines the roles of stretching means and piston member, while the sealing barrier integrates both sealing functions (between compression means and liquid pump, and between feeding duct and preform neck) into a single barrier, thereby simplifying the overall device structure while maintaining the ability to apply pressure peaks for precise shaping
2Manufacturing precision
If compression means are added to temporarily increase liquid pressure, then the container shaping is improved, but the ease of manufacture deteriorates due to requiring modifications to existing machines
Solution Approach 1:
The stretch rod is designed to perform multiple functions: it serves as both the stretching means for axial expansion of the preform and the pressure peak application means by acting as a piston member. This multi-functionality eliminates the need for separate compression means and reduces the number of sealing mechanisms required, directly resolving the contradiction between shaping precision and device complexity
Solution Approach 2:
The invention merges the stretching function and pressure peak application function into a single integrated system. The stretch rod combines the roles of stretching means and piston member, while the sealing barrier integrates both sealing functions (between compression means and liquid pump, and between feeding duct and preform neck) into a single barrier, thereby simplifying the overall device structure while maintaining the ability to apply pressure peaks for precise shaping
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 simplifies the process of applying pressure peaks, reduces equipment complexity, and allows for precise shaping of containers with intricate designs, enhancing the efficiency and cost-effectiveness of the hydro forming process.
Implementation Method 1
driving said piston member when the sealing barrier is closed such that the liquid pressure in the closed volume increases
Implementation Method 2
injecting the incompressible liquid from the source in the inner volume of the preform through the outlet
Data Source
Figure 1
Figure 2~3
Figure 4~7
AI summary
The method comprises the following steps: placing the outlet (18) of an injection device in tight fluidic communication with a preform (2), injecting liquid in the inner volume of the preform (2) through the outlet (18), closing a sealing barrier (57, 82) between the inner volume (10) and the liquid source (22), the closed sealing barrier forming a fluid tight closed volume (58), placing a piston member (40, 70) in said closed volume driving said piston member (40, 70) such that the liquid pressure in the closed volume (58) increases. During the actuation of the piston member, the piston member enters at least in part inside the inner volume of the preform.