Push-Pull Cable Valve Pin Actuation for Low-Height Mold Nozzles
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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 reciprocation of valve pins and molten plastic delivery.
Innovation Solution
A molten plastic delivery system utilizing a push-pull cable actuation mechanism with a bell crank and valve pin coupler, allowing angular movement to control the valve pin's position within the nozzle channel, thereby optimizing the use of space and facilitating efficient molten plastic flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional 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 flow, but the height of the mold assembly increases due to limited spacing
Solution Approach 1:
The bell crank mechanism converts linear actuator motion into angular/rotational motion of the valve pin through a lever arm configuration. This dimensional transformation allows the valve pin to be reciprocated horizontally while the actuator can be positioned vertically, effectively utilizing three-dimensional space and reducing the mold assembly height without compromising valve pin control capability.
Solution Approach 2:
The bell crank acts as an intermediary mechanism between the actuator and the valve pin. It translates the actuator's linear motion into the valve pin's reciprocating motion through angular movement, enabling compact space utilization while maintaining effective valve pin control for molten plastic flow regulation.
2Length of stationary object
If the mold assembly height is minimized to accommodate limited spacing, then space utilization is improved, but the reciprocation of the valve pin becomes constrained
Solution Approach 1:
By converting linear actuator motion into angular motion through the bell crank's lever arm, the system achieves valve pin reciprocation in a horizontal dimension while keeping the vertical dimension (mold assembly height) minimized. This dimensional separation resolves the conflict between compact height and effective valve pin operation.
Solution Approach 2:
The bell crank mechanism introduces dynamic angular movement to transform the static space constraint into a functional advantage. The rotating lever arm provides variable mechanical advantage throughout its motion cycle, enabling full valve pin reciprocation stroke within a compact vertical envelope, thus maintaining ease of operation despite minimized height.
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 enables efficient control of molten plastic flow while minimizing the height of the mold assembly, enhancing the operational efficiency and space utilization in plastic injection molding processes.
Implementation Method 1
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; 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
Data Source
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AI summary
The present invention refers to a molten plastic delivery system comprising: a nozzle defining a nozzle channel having a downstream nozzle channel opening; a valve pin is reciprocable within the nozzle channel between a closed position and an open position; 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; a push-pull cable is coupled to the second arm 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.