Split Ring Seal for Injection Molding Nozzle Leakage
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Solution Overview
Problem
Existing injection molding nozzles face challenges in preventing pressurized melt from escaping due to thermal expansion and deformation, which leads to leakage and increased heat transfer, affecting the efficiency and accuracy of the molding process.
Innovation Solution
The use of split ring seals received in grooves on the nozzle body, allowing for displacement relative to the groove, maintains separation between the nozzle body and the gate recess, reducing leakage and heat transfer by providing a resilient and thermally stable sealing mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional seals are used to prevent melt leakage, then sealing capability is improved, but thermal expansion and deformation cause the seals to lose contact with the mold member surface
Solution Approach 1:
The seal member is made from a material with specific thermal expansion characteristics that allow it to maintain optimal contact pressure with the mold member across temperature variations. The coefficient of thermal expansion of the seal material is carefully selected to compensate for thermal deformation, ensuring continuous sealing contact without mechanical adjustment.
Solution Approach 2:
The invention utilizes controlled thermal expansion of the seal member to maintain sealing contact. As the seal material expands thermally, it compensates for the gap between the nozzle and mold member, keeping the seal engaged with the surface despite thermal deformation of the nozzle structure.
2Productivity
If the nozzle is heated to maintain melt flow, then productivity is improved, but heat transfer to the mold member increases causing energy loss
Solution Approach 1:
A thermally insulating layer is introduced as an intermediary between the heated nozzle and the cooler mold member. This intermediate layer reduces direct heat transfer to the mold while allowing the nozzle to maintain its heating for continuous melt flow, thus preventing energy loss without compromising productivity.
Solution Approach 2:
A thin film or shell-like insulating layer is applied to the nozzle surface, providing thermal isolation. This flexible insulating layer maintains the nozzle temperature for melt flow while minimizing heat conduction to the mold member, reducing energy loss.
3Manufacturing precision
If the seal is made rigid to maintain position, then manufacturing precision is improved, but the seal cannot accommodate thermal deformation
Solution Approach 1:
The seal member is designed with dynamic characteristics, allowing it to move and deform within certain limits in response to thermal changes. This dynamic capability enables the seal to adapt to thermal deformation while maintaining adequate sealing contact, combining position accuracy with thermal adaptability.
Solution Approach 2:
The seal is constructed from composite materials combining rigid structural elements with flexible sealing portions. The rigid parts maintain positional accuracy, while the flexible portions accommodate thermal deformation, achieving both manufacturing precision and thermal adaptability simultaneously.
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 effectively prevents melt leakage and reduces heat transfer between the nozzle and mold components, enhancing the efficiency and accuracy of the injection molding process by maintaining a consistent seal despite thermal changes.
Implementation Method 1
relying on elasticity of the sealing member to maintain adequate retention forces
Implementation Method 2
a gap established between a gap sealing surface associated with the nozzle and a gap sealing surface associated with the mold member is effective to inhibit flow of melt through the gap
Data Source
AI summary
An apparatus for injection molding wherein melt is conveyed to a gate in fluid communication with at least one mold cavity comprises a nozzle for conveying melt, the nozzle having an inlet for admitting melt, at least one outlet for directing melt to mold cavities and received within a recess of the gate, a nozzle body having a passage therethrough for conveying melt from the inlet to the outlet, and at least one split ring seal received in a groove in the exterior of the nozzle body so as to be displaceable relative to the associated groove, the split ring seal having an outside perimeter for contacting the surface of the recess of a gate, the split ring seals maintaining separation of the periphery of the nozzle body from the surface of the recess with the outlet positioned within the recess. Each split ring seal advantageously comprises overlapping end segments abuttingly engaged with the outlet positioned within the recess.