Piston Member Pressure Spike for Hydraulic Blow Molding
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Solution Overview
Problem
Existing hydraulic blow molding processes require complex modifications to machines and additional sealing mechanisms to apply a second pressure peak for precise shaping of containers, which is costly and time-consuming, and often results in pressure loss and contamination.
Innovation Solution
A method using a stretch initiation rod system and a piston member to create a pressure spike within the preform by moving the piston member inside the closed volume of the preform, allowing for precise control of pressure without additional machine modifications, and reducing the risk of contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If compression means are used to temporarily increase liquid pressure to create a pressure peak, then the preform can be completely shaped into the container, but two sealing mechanisms with actuators are required, increasing device complexity
Solution Approach 1:
The patent combines the stretch rod function with the pressure peak generation function. The stretch rod serves dual purposes: mechanically stretching the preform and acting as a piston to generate the pressure peak by being retracted into the preform after liquid injection, thereby eliminating the need for separate compression means and reducing sealing mechanism complexity
Solution Approach 2:
The stretch rod is designed to perform multiple functions: initial mechanical stretching of the preform, sealing during liquid injection, and subsequent piston action to generate the pressure peak for final shaping. This multi-functionality reduces the number of components and simplifies the overall device structure
2Ease of operation
If an air vent is provided in the stretch rod to assist axial expansion, then the preform can be deformed, but pressure control precision is reduced due to pressure loss in the air vent
Solution Approach 1:
The patent removes the air vent from the stretch rod, eliminating the pressure loss pathway. Instead, the stretch rod is designed to be retracted into the preform after liquid injection, creating a sealed system that allows precise pressure control while still enabling preform expansion through the piston action
3Stress or pressure
If the molding cavity volume is reduced to increase pressure, then the pressure peak can be applied, but machine modifications are required, increasing device complexity and implementation cost
Solution Approach 1:
The patent utilizes the existing stretch rod and liquid injection system to generate the pressure peak without requiring modifications to the molding cavity or machine structure. The stretch rod itself serves as the piston, and the liquid already injected into the preform provides the medium for pressure generation, making the system self-sufficient
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
Enables simple and precise application of a second pressure peak for shaping containers, improving throughput and reducing machine complexity and contamination risks, while maintaining control over pressure profiles.
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
introducing a pressurized liquid into said preform to expand said preform
Data Source
AI summary
Use of optimized piston member for generating peak liquid pressure. A one-step hydraulic blow molding system and method for forming a preform and a liquid filled container from the preform. The machine and method include a sealing mechanism that forms a seal primarily utilizing compressive forces in an axial direction to prevent the leakage of liquid blow medium. The sealing mechanism includes an axial end face of a forming head and an upper axial surface of a neck ring.