Check Ring Closure Detection via Torque-Pressure Correlation
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Solution Overview
Problem
Existing injection molding machines with check rings face challenges in accurately determining the closure time due to variations in resin pressure and torque, leading to inconsistent resin volume and quality issues, especially when the check ring is already closed or does not close during injection, and require additional sensors that may not accurately detect pressures close to the check ring.
Innovation Solution
An injection molding machine equipped with torque detecting means, resin pressure detecting means, and correlation coefficient calculating means to determine the check ring closure by analyzing the correlation between screw torques and resin pressures during forward movement, allowing for accurate detection without additional special parts, regardless of the metering stroke distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is disposed within the cylinder behind the check ring to detect resin pressure, then the closure timing can be detected, but the device complexity increases and the measurement precision deteriorates when the metering stroke is small because the sensor position is fixed relative to the cylinder rather than the check ring position
Solution Approach 1:
The patent replaces the mechanical pressure sensor installation system with a torque detection system. Instead of mechanically installing a pressure sensor at a specific position behind the check ring, the system uses torque detecting means to measure the torque applied to the screw during forward movement. The closure timing is determined by analyzing changes in torque characteristics, which indirectly reflects the check ring closure state without requiring direct mechanical sensor placement.
Solution Approach 2:
The patent introduces torque as an intermediary parameter to detect check ring closure. Rather than directly measuring resin pressure behind the check ring, the system measures torque on the screw, which serves as an intermediary that reflects the pressure changes and closure state. The correlation coefficient calculating means then processes this intermediary torque data to determine closure timing accurately.
2Manufacturing precision
If the check ring closure timing is not accurately detected, then the resin volume consistency deteriorates and molded article quality decreases, but adding more sensors increases device complexity and cost
Solution Approach 1:
The patent enables the existing torque detecting means and resin pressure detecting means to serve dual purposes: they not only detect their primary parameters (torque and pressure) but also work together to determine check ring closure timing. The system uses the correlation between these two parameters to infer closure state, making the existing sensors serve multiple functions without adding more detection devices.
Solution Approach 2:
The patent implements a feedback mechanism where the correlation coefficient calculating means continuously monitors the relationship between torque and resin pressure during screw forward movement. When the correlation coefficient exceeds a predetermined threshold, the system determines that the check ring has closed and issues a determination signal. This feedback loop enables real-time closure detection and can trigger alerts or adjustments to maintain resin volume 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 determination of check ring closure time, improving the consistency of resin volume and quality by accurately discriminating between cases where the check ring is closed, opening, or not closing during injection, without the need for additional sensors, thus enhancing the overall molding process.
Implementation Method 1
torque detecting means for detecting the torque applied to the screw
Implementation Method 2
resin pressure detecting means for detecting the resin pressure
Data Source
AI summary
Torques and resin pressures applied to a screw are detected during the forward movement of the screw and coefficients of correlation between the detected torques and resin pressures are calculated. When the check ring is open, the flight of the screw receives resin pressure, and the screw torque increases proportionally to the resin pressure due to resin backflow, so the coefficients of correlation between the screw torques and the resin pressures are higher than a reference value. When the check ring closes, the flight of the screw no longer receive resin pressure, so the screw torque decreases and the coefficients of correlation become lower than the reference value. The check ring is determined to be closed when the coefficients of correlation become lower than the reference value.