Carrier Assembly for Internal Threads in ISBM
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Solution Overview
Problem
Current injection stretch blow molding (ISBM) machines are unable to produce containers with internal threads, which are desirable for better seals and aesthetics, as they typically only create containers with external threaded necks.
Innovation Solution
A carrier assembly with a thread-forming portion and a pinion insert is used to create internal threads in the parisons, which are then stretch blow molded into molded articles with internal threads, and a specialized ejection station tooling is employed to rotate the articles off the carrier assembly, allowing for the removal of internally-threaded molded articles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional ISBM machines are used to produce containers, then the production process is simple and efficient, but the containers can only have external threaded necks and cannot achieve internal threading for better seals and aesthetics
Solution Approach 1:
The patent implements internal threading by nesting a carrier assembly with thread-forming portions inside the parison during injection molding. The carrier insert with threaded protrusions is positioned within the parison cavity, allowing molten resin to flow around and form internal threads as it sets, effectively creating a nested structure where the threading mechanism is embedded within the molding process
Solution Approach 2:
The patent introduces a carrier assembly as an intermediary component between the injection molding system and the final container product. This carrier assembly includes thread-forming portions that temporarily support and shape the internal threads during manufacturing, then facilitate their removal to leave the desired internal threading in the finished container
2Adaptability or versatility
If a carrier assembly with thread-forming portions is used to create internal threads in parisons, then internally-threaded containers can be produced, but the ejection process becomes more complex requiring specialized tooling to rotate articles off the carrier assembly
Solution Approach 1:
The patent employs dynamic ejection mechanisms where the ejection station tooling rotates the molded articles relative to the carrier assembly to disengage them. This dynamic approach allows the rigid internal threads to be formed during molding, then the entire article-carrier assembly rotates to enable clean separation without damaging the delicate internal threading structure
Solution Approach 2:
The ejection process is segmented into distinct phases: first the molded article is formed on the carrier assembly, then the assembly rotates to a separate ejection station, and finally the article is disengaged from the carrier. This segmentation allows complex internal threading to be created in one phase while simplifying the ejection process in another phase
3Reliability
If internal threads are formed in the parison during injection molding, then sealing capabilities and aesthetics are enhanced, but the molding process requires additional thread-forming components
Solution Approach 1:
The patent applies preliminary action by forming the internal threads during the injection molding process itself, rather than adding them as a separate post-processing step. The thread-forming portions of the carrier assembly are in place before injection, so the molten resin flows around them and creates the threaded structure as it solidifies, ensuring threads are formed while the material is still pliable
Data Source
AI summary
A carrier assembly for injection molding a parison with internal threads. The carrier assembly may be used with an injection stretch blow molding machine that includes a core rod. The carrier assembly comprises a carrier insert surrounding a portion of the core rod. The carrier insert includes a thread-forming portion presenting an interior radial surface and an exterior radial surface. The interior radial surface is configured to be positioned adjacent to the core rod, and the exterior radial surface includes a threaded protrusion configured to extend away from the core rod. The carrier assembly also includes a pinion insert surrounding at least a portion of the threaded protrusion of the thread-forming portion of the carrier insert. The pinion insert is spaced apart from the thread-forming portion of the carrier insert so as to present a thread-forming cavity between the pinion insert and the carrier insert.