Ultrasonic Vibration Frequency Control for Rapid Amplitude Changes
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Solution Overview
Problem
Existing ultrasonic vibration systems face challenges in achieving high processing speeds and adapting to abrupt changes in vibration amplitude requirements due to slow regulation and frequency adjustment, especially at high web speeds, leading to suboptimal processing and material guidance issues.
Innovation Solution
A system with a drive control unit that uses the desired vibration amplitude as an input signal to directly adjust the excitation frequency, bypassing conventional regulation delays, allowing immediate frequency changes to match the desired amplitude, and incorporating a frequency control module to manage these adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the sonotrode is completely switched off during non-processing intervals, then energy consumption is reduced, but the time to reach steady-state vibration amplitude increases, causing suboptimal processing at high web speeds
Solution Approach 1:
Instead of completely switching off the sonotrode during non-processing intervals, the system applies a reduced voltage amplitude that produces a subthreshold vibration level. This partial action maintains the sonotrode in a ready state with minimal energy consumption while avoiding the long startup delay associated with complete shutdown, thereby resolving the contradiction between energy savings and rapid response time.
2Ease of operation
If the sonotrode is moved back and forth during non-processing intervals, then material web guidance is improved, but processing speed is limited by the mechanical movement speed of the sonotrode
Solution Approach 1:
The system replaces mechanical movement of the sonotrode with electrical control of vibration amplitude. By using a voltage amplitude controller to adjust the excitation voltage, the system maintains material web guidance through controlled vibration presence/absence without requiring physical sonotrode movement, thereby eliminating the speed limitation imposed by mechanical actuation.
3Manufacturing precision
If conventional regulation devices are used to adjust vibration amplitude, then amplitude control is achieved, but the regulation cannot adapt quickly enough to abrupt amplitude changes at high web speeds
Solution Approach 1:
The system uses a trigger device that detects upcoming processing requirements in advance and pre-adjusts the voltage amplitude before the actual processing interval begins. This preliminary action ensures that the sonotrode is already at the correct vibration amplitude when processing starts, eliminating the regulation delay that would otherwise occur during high-speed operation.
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 rapid adaptation to abrupt amplitude changes, improving processing efficiency and enabling higher web speeds by ensuring precise amplitude control without conventional regulation delays.
Implementation Method 1
The converter usually has piezoelectric elements which convert an alternating electric voltage into a mechanical vibration, namely an acoustic vibration
Implementation Method 2
The converter, the sonotrode and, if applicable, the amplitude transformer are tuned to each other in such a way that they can be made to resonate at the same ultrasonic frequency
Data Source
AI summary
A system for generating acoustic ultrasonic vibration, with a generator for generating an alternating voltage (U) with a frequency f and converter for converting the alternating voltage into acoustic ultrasonic vibration, with a control device, which captures the vibration amplitude (Aist) of the ultrasonic vibration and compares said vibration amplitude with a desired vibration amplitude (Asoll) and changes a manipulated variable with the goal of bringing the captured vibration amplitude (Aist) closer to the desired vibration amplitude (Asoll). The generator has a frequency control module with a frequency control input. The frequency control module defines, in accordance with a signal present at the frequency control input, the frequency (f) of the alternating voltage (U) to be generated. A control apparatus converts an input signal into a manipulated signal, the desired vibration amplitude (Asoll) provided as the input signal, and the manipulated signal connected to the frequency control input.