Valve-Gated Nozzle Annular Flow for Injection Molding Alignment
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Solution Overview
Problem
Existing valve gated hot runner nozzles suffer from premature wear and leakage due to misalignment of the valve pin, leading to poor cosmetic part quality, unidirectional molecular orientation, and unwanted flow lines, which weaken the structural integrity and dimensional accuracy of injection molded products.
Innovation Solution
A nozzle design featuring a nozzle body with a nozzle melt channel, a nozzle tip with angled melt channels, and a retaining device that forms an annular melt channel with decompression and compression chambers, along with a valve pin alignment mechanism to improve flow alignment and reduce residue material, facilitating efficient color change and minimizing flow lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a valve pin is used to control melt flow in the nozzle, then gate closure and opening can be achieved, but the valve pin causes misalignment leading to premature wear and leakage
Solution Approach 1:
A guide bushing is introduced as an intermediary component between the valve pin and the nozzle body. The guide bushing receives the valve pin and provides precise alignment, preventing direct contact and misalignment between the valve pin and nozzle walls. This mediator eliminates wear and leakage issues while maintaining reliable gate control.
Solution Approach 2:
The nozzle is divided into separate functional components: the valve pin for actuation, the guide bushing for alignment and support, and the nozzle body for structural integrity. This segmentation allows each component to perform its specific function optimally, with the guide bushing specifically addressing the alignment problem.
2Manufacturing precision
If a valve pin is used for gating, then precise gate control is achieved, but unidirectional molecular orientation and flow lines are created
Solution Approach 1:
The melt flow path is changed from a linear unidirectional flow to a multi-directional flow by introducing the annular channel that surrounds the valve pin. Melt flows radially in multiple directions around the pin rather than in a single direction, eliminating unidirectional molecular orientation and reducing visible flow lines.
Solution Approach 2:
The annular channel creates a curved, circular flow path around the valve pin instead of a straight linear path. This curved geometry promotes more uniform molecular orientation and distributes flow lines more evenly, reducing their visibility and impact on part quality.
3Device complexity
If conventional nozzle design is used, then simple structure is maintained, but substantial residue material remains requiring multiple injection cycles for color change
Solution Approach 1:
The nozzle internal flow path is segmented into distinct zones: the annular channel for primary melt flow, the decompression chamber for material mixing and air entrapment, and the compression chamber for final pressurization. This segmentation creates separate functional areas that improve color change efficiency without significantly increasing overall structural complexity.
Solution Approach 2:
The decompression chamber acts as an intermediary zone between the annular channel and the compression chamber. It provides a transition area where residual material from previous colors can be trapped and mixed with incoming material, facilitating more complete color changes in fewer injection cycles.
Data Source
AI summary
A valve-gated nozzle in an injection molding machine allows for smooth, blended melt flow into a mold cavity. In one example, this is accomplished through use of a valve-gated nozzle having a nozzle body with a nozzle melt channel in fluid communication with a manifold melt channel and a nozzle tip. The nozzle tip includes a first melt channel in fluid communication with the nozzle melt channel and a plurality of release melt channels between the first melt channel and an annular melt channel. The annular melt channel is formed between a retaining device and the nozzle tip. The annular melt channel includes a decompression chamber in fluid communication with respective ones of the release melt channels and a compression chamber between the decompression chamber and a mold. A pressure difference formed between the respective release melt channels and the decompression chamber and between the decompression chamber and the compression chamber blends the molten material to even and balance flow into the mold cavity.