Push-Pull Cable Nozzle Actuation for Low-Height Mold Assemblies
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Solution Overview
Problem
In plastic injection molding, existing systems face challenges in minimizing the height of mold assemblies due to limited spacing, which affects the efficient delivery and control of molten plastic through nozzle channels.
Innovation Solution
A molten plastic delivery system utilizing a push-pull cable actuation mechanism with a bell crank and valve pin configuration, where the push-pull cable is coupled to the bell crank's second arm, allowing angular movement to control the valve pin's position within the nozzle channel, thereby managing the flow of molten plastic efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional actuator is mounted upstream of the nozzle within the mold assembly to reciprocate the valve pin, then the valve pin can be controlled to prevent or allow molten plastic from exiting the nozzle channel, but the height of the mold assembly increases due to the space required for the actuator
Solution Approach 1:
The patent replaces the conventional mechanical actuator with a push-pull cable mechanism that transmits force through a flexible cable from a remote actuator location. This substitution allows the valve pin to be controlled without mounting a bulky actuator directly in the mold assembly, thereby reducing the mold assembly height while maintaining reliable valve pin reciprocation for controlling molten plastic flow.
Solution Approach 2:
The push-pull cable acts as an intermediary element that transmits the actuating force from the actuator to the valve pin over a distance. This intermediary mechanism enables the separation of the actuator from the immediate nozzle area, allowing the actuator to be positioned in a location that does not increase mold assembly height, while still effectively controlling the valve pin.
2Volume of moving object
If the spacing in the injection molding apparatus to accommodate the mold assembly is limited, then the manufacturing process can be compact, but it becomes difficult to accommodate the actuator and other components necessary for molten plastic delivery and control
Solution Approach 1:
The push-pull cable mechanism allows the actuator to be positioned in a different spatial dimension or location away from the immediate mold assembly area. The cable transmits force through three-dimensional space, enabling the system to accommodate necessary components without increasing the compact mold assembly footprint, thus maintaining small volume while preserving component adaptability.
Solution Approach 2:
The system segments the actuation function from the mold assembly proper by using a remotely mounted actuator connected via push-pull cable. This segmentation allows the mold assembly to remain compact while the actuator can be positioned separately, accommodating all necessary components without increasing the overall mold assembly volume.
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 minimizes the height of the mold assembly while ensuring precise control over molten plastic flow, enhancing the efficiency and accuracy of the injection molding process by allowing the valve pin to reciprocate between open and closed positions using the push-pull cable mechanism.
Implementation Method 1
a push-pull cable is coupled to the second arm such that angularly pushing the second arm via the push-pull cable moves the valve pin to the open position and angularly pulling the second arm via the push-pull cable moves the valve pin to the closed position
Implementation Method 2
a bell crank having a first and second arms that are connected at and rotatable about a pivot, the first arm is coupled to the valve pin
Data Source
AI summary
A molten plastic delivery system is disclosed having a nozzle defining a nozzle channel with a downstream nozzle channel opening. A valve pin is reciprocable within the nozzle channel between a closed position and an open position. The system includes a bell crank having first and second arms that are connected at and rotatable about a pivot. The first arm is coupled to the valve pin and the second arm is coupled to a push-pull cable such that angularly pushing the second arm about the pivot via the push-pull cable moves the valve pin to the open position and angularly pulling the second arm about the pivot via the push-pull cable moves the valve pin to the closed position.