Optical Pressure Controller for Injection Molding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing injection molding machines face challenges in controlling mold pressure accurately and quickly reducing pressure to prevent stress deformation in molded articles, particularly in thin-wall molding, due to high peak pressures and the need for additional pressure sensors, which increase costs.
Innovation Solution
A pressure controller for injection molding machines that includes an injection screw drive unit, injection pressure detection, screw movement detection, and in-mold pressure estimation, allowing for precise control of injection and in-mold pressures using PID operations to maintain set pressures and reduce pressure variations, thereby preventing stress deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure control is performed based on pressure detected by a load cell in the dwell step, then the pressure on the screw can be controlled to become a set pressure, but the pressure in the mold is not always the same as the pressure to the screw, making it difficult to reduce the pressure in the mold to a desired pressure at a desired response speed
Solution Approach 1:
The patent replaces the mechanical pressure measurement system (load cell detecting screw pressure) with an optical measurement system (transmission type pressure sensor using light transmission through the mold). This substitution enables direct measurement of mold pressure with high response speed, eliminating the delay inherent in mechanical systems while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces a transmission type pressure sensor as an intermediary element that directly measures mold pressure through light transmission. This intermediary provides accurate real-time pressure data from the mold cavity itself, rather than inferring mold pressure from screw pressure, enabling precise and rapid pressure control.
2Measurement precision
If a pressure sensor is provided in the mold to control the pressure detected to become a predetermined pressure, then the pressure in the mold can be controlled accurately, but it is necessary to provide the additional pressure sensor in the mold, which increases the cost
Solution Approach 1:
The patent replaces complex mechanical pressure sensors with a simpler optical measurement system using light transmission through the mold. This substitution reduces device complexity and cost while maintaining the ability to measure mold pressure accurately, as the optical system uses light sources and detectors rather than complex mechanical elements.
Solution Approach 2:
The patent creates an optical copy or representation of the pressure state by measuring light transmission properties rather than directly measuring mechanical pressure. This copying approach simplifies the measurement system, eliminating the need for complex pressure sensing elements while still providing accurate pressure information through optical property changes.
3Stress or pressure
If the screw is moved backward by position control for depressurization in the latter half of the filling step, then depressurization can be performed, but it is difficult to reduce the pressure in the mold at a desired response speed
Solution Approach 1:
The patent implements a feedback control system that uses real-time optical pressure measurement data from the mold to dynamically adjust screw movement. The high response speed of the optical sensor provides immediate feedback on pressure changes, enabling the control system to rapidly respond and adjust screw position to achieve desired pressure reduction, overcoming the slow response of open-loop position control.
Solution Approach 2:
The patent replaces slow mechanical position control with a hybrid system that uses fast optical pressure measurement combined with controlled screw movement. The optical measurement system provides rapid pressure detection, enabling much faster response times compared to relying solely on mechanical position control, while the screw movement mechanism provides the actual pressure reduction.
Data Source
AI summary
A pressure controller for an injection molding machine capable of reducing variations of pressure in a mold in molding cycles and providing molded articles of stable quality is provided. The pressure controller includes an in-mold pressure estimation unit for estimating a pressure in the mold based on an injection pressure detected with an injection pressure detection unit, and an amount of movement of a screw detected with a screw movement amount detection unit, and an in-mold pressure control unit for controlling such that the estimated in-mold pressure becomes a set in-mold pressure after the pressure control is performed in a dwell step with an injection pressure control unit.