Injection Head Mechanical Linkage for Stretch Blow Molding
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Solution Overview
Problem
The existing container fabrication processes face challenges in accurately coordinating the liquid supply and injection valve opening during the stretch blow molding process, leading to potential preform breakage or system pressure issues due to time shifts and manufacturing tolerances.
Innovation Solution
A mechanical servo-control system is implemented in the injection head, where the liquid under pressure activates the injection valve, ensuring precise timing and coordination between liquid supply and valve opening, eliminating the need for frequent valve response checks and reducing time shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If electronic control is used to coordinate fluid supply and injection valve opening, then the process can be automated, but time shifts and synchronization errors occur due to valve response time variations
Solution Approach 1:
The patent replaces the electronic control system with a mechanical linkage system. The injection valve is directly coupled to the piston rod through mechanical linkages, so that the valve opening is mechanically driven by the piston rod position rather than by electronic signals. This eliminates time shifts and synchronization errors because the valve response is directly tied to the mechanical position of the piston rod through rigid linkages.
2Productivity
If the injection valve is opened before fluid supply is complete, then productivity increases, but preform breakage occurs due to cooling from residual water
Solution Approach 1:
The patent implements a feedback mechanism where the position of the piston rod is continuously monitored and used to control the injection valve opening. The valve is mechanically linked to the piston rod, so the valve opening timing automatically adjusts based on the actual piston rod position and fluid supply status. This feedback ensures the valve opens at the precise moment when fluid supply is complete, preventing preform breakage while maintaining high productivity.
3Manufacturing precision
If the injection valve response time varies due to manufacturing tolerances, then device complexity increases for compensation, but synchronization accuracy must be maintained
Solution Approach 1:
The patent extracts the timing control function from the electronic control system and embeds it directly into the mechanical linkage between the piston rod and injection valve. By removing the electronic timing control component, the system eliminates the need to compensate for valve response time variations through complex electronic adjustments. The mechanical linkage inherently provides consistent, tolerance-insensitive timing synchronization.
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 solution provides high accuracy and reliability in the container fabrication process, preventing preform breakage and system pressure issues, while simplifying the coordination of operations and reducing equipment complexity.
Implementation Method 1
The preform is expanded into the cavity of the mold by the action of a stretching rod inserted into a mouth of the preform, combined with the action of a working fluid injected into the preform under pressure
Implementation Method 2
The pressurized fluid causes the preform to inflate, expanding primarily radially
Data Source
AI summary
An injection head for the fabrication of a container from a preform. The injection head interfaces with a preform to establish fluid communication between a liquid supply and the preform. An injection valve is disposed within the injection head and is configured to selectively permit fluid communication through the injection head. A liquid supply control mechanism and a control mechanism of the injection valve's opening allow fluid communication through the injection head. The control mechanism of the injection valve's opening is activated by the liquid under pressure in the injection head cavity when the liquid supply is opened.