Ultrasonic Polymer Melt Temperature Measurement
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Solution Overview
Problem
Accurate measurement of polymer melt temperature during injection molding is challenging due to the slow response speed of traditional thermocouples and the high cost and limited application of infrared optic-fiber temperature sensors, with no effective quantitative measurement methods available.
Innovation Solution
A method combining mold cavity pressure information with ultrasonic signals to measure the sound velocity and pressure of the polymer melt, using an ultrasonic probe and pressure sensor, and calculating the melt temperature in real-time through a derived formula and Newtonian-iterative numerical method, allowing for on-line monitoring and diagnosis of the molding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional thermocouple is used for temperature measurement, then the measurement method is simple and low cost, but the response speed is slow and it can only measure surface temperature
Solution Approach 1:
The patent replaces the mechanical contact-based thermocouple system with an ultrasonic acoustic field-based measurement system. By measuring ultrasonic sound velocity in the polymer melt and combining it with pressure data, the system calculates temperature without physical contact, achieving both high response speed and accurate bulk temperature measurement.
Solution Approach 2:
The patent changes the measurement parameter from direct temperature sensing to indirect temperature calculation through ultrasonic sound velocity measurement. The sound velocity of ultrasonic waves in the polymer melt is measured, and temperature is derived from this parameter combined with pressure data through established relationships, enabling rapid and accurate temperature determination.
2Measurement precision
If infrared optic-fiber temperature sensor is used, then the temperature measurement accuracy is high, but the cost is high and application is limited
Solution Approach 1:
The patent employs inexpensive ultrasonic transducers and pressure sensors that can be easily manufactured and replaced, replacing the costly infrared optic-fiber sensors. These ultrasonic-based measurement devices significantly reduce system cost while maintaining measurement accuracy and improving application feasibility in industrial injection molding environments.
Solution Approach 2:
The patent substitutes the expensive infrared optical measurement system with a more economical ultrasonic acoustic measurement system. The ultrasonic transducers and pressure sensors used in this approach are significantly cheaper and more durable than infrared optic-fiber sensors, making the technology economically viable for widespread industrial application.
3Measurement precision
If thermocouple measures melt temperature in the mold, then the measurement is obtained, but the result is far from the actual melt temperature variation
Solution Approach 1:
The patent introduces ultrasonic sound velocity as an intermediary parameter to measure polymer melt temperature. Instead of directly measuring temperature with a thermocouple that disturbs the system, the ultrasonic waves pass through the melt without significant interaction, and the sound velocity changes provide accurate information about the bulk temperature without the reliability issues of contact measurement.
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 accurate, real-time measurement of melt temperature and potential on-line quality control of molded products at a lower cost, with high convergence efficiency and potential for industrial promotion and theoretical research significance.
Implementation Method 1
measurement of ultrasonic sound velocity c of melt during injection molding
Implementation Method 2
measurement of ultrasonic sound velocity c of melt during injection molding
Implementation Method 3
measurement of melt pressure P during injection molding
Implementation Method 4
obtaining melt temperature T during injection molding by a formula as follows: T=f(T, P)−f(T, P0)
Data Source
AI summary
The present disclosure discloses a method for on-line measurement of the polymer melt temperature, comprising: on-line measurement of ultrasonic sound velocity c of melt in an injection molding process, on-line measurement of melt pressure P in the injection molding process, and obtaining melt temperature T in the injection molding process by formula (1). The present disclosure also discloses an apparatus for on-line measurement of the polymer melt temperature. The method and the apparatus provided in the present disclosure may enable on-line and in-situ characterization of the melt density and further enable on-line quantitative measurement of the melt quality. Compared with infrared measurement methods, the method provided herein is significantly reduced in cost, which is of great significance to theoretical researches of crystallization process and shear heating.