Injection Blow Molding Manifold Alignment Under Thermal Expansion
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Solution Overview
Problem
In injection blow molding machines, hydraulic backpressure and thermal expansion cause the resin manifold and base plate to deform, leading to misalignment and resin leakage, especially in high cavitation applications where maintaining a zero gap between nozzle gate inserts and nozzles is crucial.
Innovation Solution
An injection station design featuring a die plate with a keyway for securing a draw bar, a base plate with projections and notches for engagement, and a manifold secured to the base plate, which together maintain alignment and stability under high pressure and temperature conditions, preventing bowing and misalignment of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a zero gap is maintained between nozzle gate insert and nozzle to allow independent movement due to thermal expansion, then adaptability to thermal expansion is improved, but hydraulic backpressure causes resin leakage
Solution Approach 1:
The patent applies preliminary anti-action by pre-loading the nozzle assembly into the gate insert with a force that compresses a resilient element (such as an O-ring or elastomeric seal). This pre-compression creates an initial sealing force that counteracts the hydraulic backpressure generated during injection. The resilient element is positioned and compressed before injection occurs, establishing a sealing mechanism that actively resists the upcoming pressure load, preventing resin leakage while maintaining the zero gap design for thermal expansion accommodation.
2Temperature
If heat is applied to resin manifold and base plate to maintain injection temperature, then injection operating temperature is maintained, but component deformation occurs
Solution Approach 1:
The patent segments the heating function by applying heat selectively to specific components rather than uniformly heating the entire assembly. The resin manifold receives targeted heating to maintain injection temperature, while the base plate is either heated separately or allowed to remain at a lower temperature. This segmentation of thermal zones prevents uniform thermal expansion that would cause misalignment, while still ensuring the manifold maintains the required injection temperature for proper resin flow and molding.
3Reliability
If hydraulic backpressure forces manifold and base plate backward and causes bowing, then sealing relationship is compromised, but structural integrity must be maintained
Solution Approach 1:
The patent applies local quality by concentrating structural reinforcement and sealing features at the critical interface between the nozzle assembly and gate insert, rather than uniformly strengthening the entire manifold and base plate assembly. A resilient sealing element is positioned locally at the sealing interface to accommodate pressure-induced deformations. Additionally, localized ribs or stiffening features may be added near the nozzle mounting area to resist bowing, while other areas of the manifold maintain their original lightweight construction. This approach preserves overall structural integrity while ensuring reliable sealing under hydraulic backpressure.
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
The design ensures consistent alignment and secure positioning of the resin manifold, preventing resin leakage and maintaining operational efficiency even under significant hydraulic forces and thermal expansion, thereby enhancing the reliability of the injection blow molding process.
Implementation Method 1
the difference in thermal expansion of the cavities and the manifold since the cavities and the manifold may be operated at different temperatures
Implementation Method 2
hot melt resin will fill the gap and be cooled down enough to form a seal during injection of the hot melt resin into the cavity
Data Source
AI summary
An injection station of an injection blow molding machine and a method for forming parisons and molded articles. The injection station includes a die plate with a keyway formed through a least a portion of a surface of the die plate. The keyway separates front and back portions of the surface of the die plate. The injection station further includes a resin injection tooling comprising a draw bar, with at least a portion of the draw bar operable to be positioned within the keyway of the die plate, a base plate secured to a back side of the draw bar and operable to be secured to the back portion of the surface of the die plate and, and a manifold secured to a top of the base plate, with the manifold being configured to discharge resin into cavities to form the parisons.