Piezo Actuator Supply Circuit for Vibration Machining
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Solution Overview
Problem
Existing machining methods using high-frequency vibrations with small amplitudes are not effective for certain materials and conditions, resulting in inefficient workpiece machining and surface quality issues.
Innovation Solution
A method employing a vibrating tool with amplitudes of at least 5 μm and frequencies detuned by 10% to 30% from mechanical resonance, combined with a supply circuit for a piezo actuator that generates a direct and alternating voltage to avoid damaging the piezo element, allowing for larger amplitudes and smoother workpiece surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-frequency vibrations with small amplitudes are used, then the tool can operate at resonance frequencies, but the machining effectiveness and surface quality are insufficient for certain materials
Solution Approach 1:
The patent changes the vibration parameters from high-frequency/small-amplitude to lower-frequency/large-amplitude operation. Specifically, it uses vibrations with amplitudes of at least 5 μm (preferably 10-100 μm) and frequencies detuned by at least 10% from mechanical resonance, which fundamentally alters the machining interaction and improves both effectiveness and surface quality
2Reliability
If large vibration amplitudes are used to improve machining effectiveness, then the surface quality improves, but the risk of damaging piezo elements increases
Solution Approach 1:
The supply circuit performs preliminary action by generating a direct voltage component before the alternating voltage is applied to the piezo element. This pre-biases the piezo element in one polarity, ensuring that even with large alternating voltage amplitudes, the element operates in a safe voltage range and avoids damage from reverse polarity inputs
3Ease of operation
If the working frequency is set at mechanical resonance frequency, then the vibration amplitude can be maximized, but the machining effectiveness is reduced for certain materials
Solution Approach 1:
Instead of operating at the mechanical resonance frequency to maximize vibration amplitude, the patent inverts the approach by deliberately detuning the working frequency by at least 10% from the resonance frequency. This counterintuitive approach, combined with using active vibration generation at lower frequencies with higher amplitudes, achieves better machining effectiveness for certain materials
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
The method achieves more effective workpiece machining with smoother surfaces by using larger amplitudes and lower frequencies, reducing the risk of tool damage and improving machining efficiency, especially in roughing processes.
Implementation Method 1
The actuator can be located between the actual tool head (e.g. drill) and a drive component of a machine tool... When the electromechanical transducer of the actuator is a piezo element...
Implementation Method 2
The voltage generator can receive alternating current and can have a capacitor C1 connected in series to the input and a half-wave rectifier in parallel to the mentioned series connection
Implementation Method 3
a vibration of a comparatively high frequency is superposed to a tool ('ultrasound')... the vibration has an amplitude of at least 5 μm... the vibration has a working frequency which is detuned by at least 10%... with respect to a mechanical resonance frequency
Data Source
AI summary
In a method for machining a workpiece, a cutting tool is guided relative to the workpiece, with a vibration being superposed, the amplitude of which is at least 5 μm. A supply circuit for a piezo actuator of a vibrating tool generates a voltage at the voltage output, which has a direct component and an alternating component. A supply system for a piezo actuator of a vibrating tool has the above-mentioned supply circuit which is connected to a secondary coil that is coupled to a primary coil.