Injection Molding Shutter Control via Feedback Loop
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Solution Overview
Problem
Existing injection molding systems using Water Injection Technology (WIT) face challenges with imprecise control of the shutter and fluid pressure, leading to inefficiencies, potential explosions, and poor product quality due to rough coordination of the shutter and water injection sequences.
Innovation Solution
A system with a third electronic control unit external to the press, allowing precise control of the shutter position and fluid injection dynamics, using continuous movement and sophisticated logic based on real-time process parameters to optimize the molding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a timer-based control system is used to coordinate shutter and water injector activation, then the system is simple to implement, but the coordination precision between shutter and water injection deteriorates
Solution Approach 1:
The patent introduces a feedback mechanism where the control system continuously monitors the actual position of the shutter and the actual pressure of the water injector, comparing these values with predetermined target values. When deviations are detected, the control system automatically adjusts the shutter position and water injection pressure to maintain precise coordination. This feedback loop transforms the open-loop timer-based control into a closed-loop control system, resolving the contradiction between system simplicity and coordination precision.
2Speed
If fluid-operated actuators are used to move the shutter, then the actuation is simple and fast, but the position control precision deteriorates
Solution Approach 1:
The control system incorporates position sensors that continuously monitor the actual position of the shutter during movement. The feedback mechanism compares the actual position with the target position and automatically adjusts the fluid-operated actuator to achieve precise positioning. This allows the system to maintain the speed advantage of fluid-operated actuators while eliminating their inherent positioning inaccuracy through active feedback control.
3Ease of operation
If the shutter is moved by fluid-operated actuators with imprecise control, then the system is easier to operate, but the product quality deteriorates
Solution Approach 1:
The feedback control system automatically compensates for the imprecise control characteristics of fluid-operated actuators by continuously monitoring shutter position and water injection pressure, comparing them with target values, and making real-time adjustments. This maintains ease of operation as the system remains automatically controlled while dramatically improving product quality through precise coordination of the molding process parameters.
4Device complexity
If water injection pressure is not regulated inside the cavity, then the injection system is simpler, but the process control precision deteriorates
Solution Approach 1:
The control system incorporates pressure sensors that continuously monitor the actual water injection pressure inside the mold cavity. The feedback mechanism compares the actual pressure with the predetermined target pressure and automatically adjusts the water injection system to maintain precise pressure control throughout the injection process. This adds minimal complexity to the injection system while dramatically improving process control precision and product consistency.
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
Enables precise control of the molding process, improving efficiency, safety, and product quality by finely regulating the fluid pressure and material flow, reducing the risk of explosions and ensuring consistent product quality.
Implementation Method 1
a fluid injector (liquid or gas or vapor) to inject pressurized fluid into the cavity and, through the action of the fluid, remove material from the molded object
Implementation Method 2
regulate, by moving the shutter with positional continuity and/or according to a programmed dynamic profile, a flow of molten material that the pressurized fluid is removing from the cavity
Data Source
AI summary
A method is described for injection molding a hollow object. The method has the steps of:(i) waiting for a cycle start signal from a press,(ii) upon receiving the cycle start signal, driving an actuator in order to regulate a flow of molten material towards a mold cavity by displacing a shutter,(iii) after a certain time, or simultaneously, sending a fluid injection signal to an injection unit in order to command the latter to activate a fluid injector to inject fluid under pressure into the mold cavity;(iv) after a certain time, or simultaneously, driving the actuator in order to regulate, by displacing the shutter with positional continuity and/or according to a programmed dynamic profile, a flow of molten material that the pressurized fluid is removing from the cavity and pushing towards the press.