Ultrasonic Tool Holder Sensing for Resonance Frequency Tracking
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Solution Overview
Problem
In ultrasonic machining, the resonant frequency of the tool's oscillating system changes due to heating, vibration damping by the workpiece, and coupling effects, leading to reduced vibration amplitude and machining efficiency, which existing methods struggle to accurately detect and adapt to.
Innovation Solution
A device with a tool holder containing an ultrasonic transducer and a sensor device made of piezoelectric material with electrode segments for detecting axial and bending vibrations, allowing for direct measurement of ultrasonic vibration parameters and continuous monitoring of changes in resonance frequency and amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the tool is operated at its initial resonant frequency, then the vibration amplitude is maximized initially, but the resonant frequency drifts during machining due to heating and damping, causing the vibration amplitude to decrease
Solution Approach 1:
The patent implements a feedback mechanism where a sensor continuously monitors the actual resonant frequency of the tool during machining operations. The control unit receives this feedback signal and automatically adjusts the excitation frequency to track the drifting resonant frequency, thereby maintaining maximum vibration amplitude throughout the machining process despite temperature changes and damping effects
Solution Approach 2:
The system transitions from a static operating frequency to a dynamic frequency adjustment mechanism. The resonant frequency is no longer fixed but is continuously adapted based on real-time conditions (temperature, damping, coupling), allowing the system to maintain optimal performance under varying operational conditions
2Device complexity
If traditional impedance-based frequency detection is used, then the detection system is simple, but it cannot accurately detect the actual resonant frequency due to complex impedance curves with multiple minima
Solution Approach 1:
The patent replaces the electrical impedance-based detection method with a direct mechanical vibration measurement approach. Instead of analyzing electrical impedance curves with multiple minima, a sensor directly measures the mechanical vibration parameters of the tool, providing unambiguous detection of the actual resonant frequency regardless of the complexity of the electrical impedance characteristics
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 higher machining accuracy by precisely detecting and adapting to changes in vibration parameters, ensuring maximum oscillation amplitude and efficiency during the machining process.
Implementation Method 1
a sensor device (40) in the tool holder for generating a sensor signal based on the ultrasonic vibration of the tool, wherein the sensor device comprises a one-piece element (41) made of piezoelectric material
Implementation Method 2
an ultrasonic transducer in the tool holder for generating the ultrasonic vibration of the tool
Data Source
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AI summary
The invention relates to a device for generating an ultrasonic oscillation in a tool (90) used for ultrasonically machining a workpiece and measuring ultrasonic oscillation parameters on the tool (90), said device comprising a tool holder (10) for holding the tool, an ultrasonic transducer (20) in the tool holder for generating the ultrasonic oscillation in the tool, a sensor mechanism (40) in the tool holder for generating a sensor signal on the basis of the ultrasonic oscillation of the tool, and a sensor signal evaluation unit (110) for analyzing the sensor signal.