Hot Channel Nozzle Valve Needle Guide Sleeve Flow Control
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Solution Overview
Problem
Existing hot channel nozzles in injection molding tools face issues with maintaining homogeneous melt consistency due to the valve needle disrupting the flow and potential re-entrainment of residual melt, leading to flow lines and inconsistencies in the molded parts.
Innovation Solution
A hot channel nozzle design featuring a valve needle guide sleeve that delimits the mass flow channel around the inlet opening, preventing melt from reaching remote areas and using recesses on the sleeve to define the melt flow path, which enhances mixing and homogeneity by ensuring uniform flow and minimizing flow line formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the valve needle is disposed in the mass flow channel to control melt discharge, then the melt flow can be controlled, but the homogeneous consistency of the melt is disturbed and flow lines are formed
Solution Approach 1:
The mass flow channel is segmented into an upstream section and a downstream section by the valve needle guide sleeve. The guide sleeve creates a delimited upstream area where melt enters through side openings, preventing the melt from reaching remote areas of the channel. This segmentation isolates the flow control function (valve needle) from the homogeneity requirement (upstream melt flow), allowing the valve needle to control discharge without disturbing the homogeneous melt consistency in the upstream region.
Solution Approach 2:
The valve needle guide sleeve acts as an intermediary element between the melt supply system and the valve needle. It delimits the mass flow channel and prevents direct contact between the melt and remote areas of the channel, while still allowing the valve needle to perform its flow control function. The guide sleeve mediates the interaction between the melt flow and the valve needle, preventing harmful interactions (flow line formation) while maintaining useful functions (discharge control).
2Productivity
If the melt enters the mass flow channel through side openings, then the melt can be supplied to the nozzle, but residual melt is retained in remote areas and re-entrained into the melt flow
Solution Approach 1:
The harmful function of residual melt retention is extracted and eliminated by the valve needle guide sleeve. The guide sleeve delimits the upstream area of the mass flow channel, effectively removing the remote areas where residual melt could be retained. By taking out the problematic region from the melt flow path, the system prevents re-entrainment of residual melt while maintaining efficient melt supply through the side openings.
3Ease of operation
If the valve needle extends through the nozzle body to the outlet opening, then the outlet can be blocked, but the melt flow is divided into partial flows that may form flow lines
Solution Approach 1:
The mass flow channel is segmented by the valve needle guide sleeve into an upstream section (where melt enters through side openings) and a downstream section (where the valve needle is positioned). This segmentation ensures that the melt flow in the upstream section remains homogeneous and does not interact with the valve needle in a way that creates flow lines. The valve needle can extend through the nozzle body for outlet blocking without dividing the melt flow into harmful partial flows.
Data Source
AI summary
In a hot channel injection molding nozzle comprising a nozzle body including a mass flow channel for a melt to be injected into a mold, wherein the nozzle body has a nozzle outlet opening at one end and an inlet opening disposed at one side of the other end of the nozzle body and a valve needle extending through the nozzle body to the outlet opening for blocking the melt flow, a valve needle guide sleeve is disposed in the nozzle body so as to delimit the mass flow channel in the area of the inlet opening with the valve needle extending through the guide sleeve.