Ultrasonic Waveguide Signal Coupling in Hot Melts
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Solution Overview
Problem
Current methods for measuring local flow velocities in hot melts, such as liquid metals or semiconductors, are inaccurate and invasive, as they either rely on optical methods limited to free surfaces or disrupt the process with invasive techniques, and existing ultrasonic methods face challenges with signal coupling and transmission losses at high temperatures.
Innovation Solution
The method involves making the end face of the ultrasonic waveguide wettable by immersing it in the melt at an angle other than 90°, cooling the waveguide, and applying a protective layer that dissolves in the melt for optimal signal coupling, ensuring good acoustic contact and minimizing transmission losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical measuring methods are used to measure flow velocities in hot melts, then measurement can be performed on free surfaces, but the method is limited to transparent media and cannot measure local velocities in non-transparent melts
Solution Approach 1:
The patent replaces optical measurement methods with ultrasonic measurement methods. The ultrasonic transducer emits ultrasonic waves that travel through the melt and reflect off particles or bubbles, allowing velocity measurement without requiring optical transparency. This substitution enables measurement in non-transparent fluids while maintaining local velocity measurement capability.
Solution Approach 2:
The patent introduces an ultrasonic waveguide as an intermediary component between the ultrasonic transducer and the melt. The waveguide transmits ultrasonic waves from the transducer into the melt and collects reflected waves, enabling non-invasive measurement while protecting the transducer from direct contact with the hot melt.
2Measurement precision
If invasive methods with test bodies immersed in the melt are used, then local flow velocities can be measured, but the process is disrupted and only rough measured values are obtained
Solution Approach 1:
The ultrasonic waveguide acts as a mediator that transmits measurement signals through the melt without requiring physical immersion of test bodies. The waveguide can be positioned outside the melt or at the boundary, transmitting ultrasonic waves through the melt to measure flow velocities while maintaining process stability and avoiding disruptions.
Solution Approach 2:
The patent replaces mechanical test bodies with ultrasonic wave-based measurement. Instead of immersing physical probes that disrupt the melt flow, the system uses ultrasonic waves that propagate through the melt and reflect off particles or bubbles, enabling non-invasive velocity measurement that maintains process stability.
3Loss of energy
If ultrasonic waves are transmitted directly into the melt from the transducer, then good signal coupling is achieved, but the piezoelectric transducer is exposed to high temperatures and chemical environments
Solution Approach 1:
The ultrasonic waveguide serves as a protective intermediary between the piezoelectric transducer and the hot melt. It transmits ultrasonic waves from the transducer into the melt while physically separating the transducer from the harsh thermal and chemical environment, allowing good signal coupling without direct transducer exposure to the melt.
Solution Approach 2:
The measurement system is segmented into distinct functional parts: the piezoelectric transducer remains in a protected environment, the ultrasonic waveguide transmits waves into the melt, and the evaluation device processes signals outside the hot zone. This segmentation allows each component to operate in its optimal environment while achieving overall system functionality.
4Object-affected harmful factors
If the ultrasonic waveguide is made with high thermal resistance to protect the transducer, then temperature protection is achieved, but ultrasonic wave transmission is attenuated
Solution Approach 1:
The ultrasonic waveguide has different thermal properties at different locations: the section in contact with the transducer has high thermal resistance to protect the piezoelectric material, while the section transmitting waves into the melt is designed for optimal ultrasonic transmission. This local differentiation of material properties allows simultaneous achievement of temperature protection and efficient wave transmission.
Solution Approach 2:
The ultrasonic waveguide may use composite material structures combining materials with different properties. The transducer interface section uses materials with high thermal resistance to protect the piezoelectric element, while the melt interface section uses materials optimized for ultrasonic wave transmission, achieving both temperature protection and efficient signal transmission.
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 approach allows for precise and non-invasive local velocity measurements in hot melts by ensuring effective signal coupling and reducing transmission losses, providing accurate and reliable data despite high temperatures.
Implementation Method 1
The essential component of the measuring device is the ultrasonic transducer in the form of a piezoelectric crystal (also called a piezoelectric transducer), which is electrically connected to a frequency generator
Implementation Method 2
using the ultrasonic Doppler method
Implementation Method 3
The essential component of the measuring device is the ultrasonic transducer in the form of a piezoelectric crystal
Implementation Method 4
The ultrasonic waves are transmitted into the fluid to be examined from the ultrasonic transducer directly into the fluid
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a method for measuring flow rates in liquid melts in a temperature range above 200 °C using an ultrasonic generator and to an associated ultrasonic waveguide according to the ultrasonic Doppler method. The aim of the invention is to provide good signal incoupling and outcoupling. This is achieved by the preparation of the wettability of the end face of the ultrasonic waveguide before the measuring operation, subsequent direct incoupling of ultrasonic measuring signals into the melt at an angle that is not equal to 90°, achieved by the immersion of the end face of the ultrasonic waveguide into the melt, outcoupling of the ultrasonic signals reflected in the melt via the end face of the ultrasonic waveguide and routing of said signals to an evaluation circuit. To prepare the wettability of the end face, the latter is mechanically and chemically cleaned and subsequently coated with a suitable material.