Vibration Welding Oscillation Damping via Dynamic Frequency Control
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Solution Overview
Problem
Existing methods for controlling mechanical vibrations, particularly in vibration welding, are limited in dynamism and efficiency, as they fail to rapidly and effectively dampen oscillations while generating sufficient frictional heat.
Innovation Solution
A method involving a dynamic frequency profile change for the excitation signal, using a voltage-controlled frequency converter to feed electromagnets, allowing for rapid excitation and damping of mechanical oscillations by converting potential energy into kinematic energy and generating phase shifts, which are then used to control amplitude and dissipate energy as heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a constant frequency excitation signal is used for vibration welding, then the system can generate frictional heat for welding, but the mechanical oscillation cannot be rapidly damped when welding is complete
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant frequency excitation signal to a dynamic time-varying frequency signal. The frequency profile changes continuously according to a predetermined function, enabling the system to adapt its excitation characteristics in real-time. This dynamic approach allows rapid damping of mechanical oscillations after welding by varying the frequency away from resonance, while maintaining high welding speed during the welding phase through constant frequency excitation.
Solution Approach 2:
The patent implements parameter changes by modifying the frequency parameter of the excitation signal over time. A predetermined frequency profile function defines how the frequency evolves during different process phases. During welding, the frequency maintains a constant value optimized for heat generation; after welding, the frequency varies according to the profile function to rapidly dampen oscillations, thus resolving the contradiction between maintaining welding productivity and reducing damping time.
2Speed
If the excitation frequency is changed rapidly to dampen oscillation, then the damping speed increases, but control precision and smoothness of transition may be compromised
Solution Approach 1:
The patent applies dynamics by using a continuous and differentiable frequency profile function that smoothly transitions the excitation frequency. This dynamic approach ensures that while the frequency changes rapidly enough to achieve fast damping, the transitions remain smooth and controlled, preventing abrupt changes that would compromise phase control precision. The predetermined function governs the evolution of frequency to balance damping speed with control precision.
Solution Approach 2:
The patent utilizes periodic action through the oscillatory nature of the excitation signal combined with a structured frequency profile. The periodic excitation maintains resonance during welding for effective heat generation, then follows a predetermined frequency variation pattern after welding to systematically dampen oscillations. This periodic approach with controlled frequency modulation ensures both rapid damping and precise phase control throughout the process.
3Adaptability or versatility
If a voltage-controlled frequency converter is used to feed electromagnets, then dynamic control of excitation is achieved, but the inductive load creates challenges for rapid excitation and de-excitation
Solution Approach 1:
The patent applies dynamics by using a voltage-controlled frequency converter that dynamically adjusts the excitation frequency according to a predetermined profile. This dynamic control system overcomes the challenges of inductive loads by continuously varying the frequency rather than attempting abrupt on/off switching. The converter adapts the excitation parameters in real-time, ensuring reliable and rapid response despite the inductive nature of the electromagnet load.
Solution Approach 2:
The patent implements parameter changes by varying the frequency parameter of the excitation signal through the voltage-controlled frequency converter. Instead of relying on abrupt amplitude switching which is problematic with inductive loads, the system changes the frequency parameter according to a predetermined profile. This approach enables reliable rapid excitation and de-excitation of the electromagnets by avoiding the issues associated with direct amplitude control of inductive loads.
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 enables highly dynamic control of mechanical vibrations, allowing for efficient damping and heat generation, enhancing the precision and speed of vibration welding processes.
Implementation Method 1
the excitation signal being generated by a voltage-controlled frequency converter, in that it feeds one or more electromagnets
Implementation Method 2
During mechanical vibration, potential energy in the magnetic field is converted into kinematic energy and vice versa, with additional friction being caused
Implementation Method 3
vibration welding generates frictional heat which can be used to heat the body portions to be welded
Data Source
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AI summary
A method for controlling, in particular damping, a mechanical oscillation of a system, in particular for vibration welding, wherein in a first time period the system is excited with an exciting signal which has a first frequency value f1, with the result that a first time profile p(t) of the phase of the exciting signal is present, in a second time period the system is excited with a frequency value profile f(t), which varies over time and is selected in such a way that, at the end of the second time period, the time profile of the phase of the exciting signal as a non-diminishing phase difference Delta_p at the first time profile p(t) of the phase, wherein the frequency value profile f(t) starts at the beginning of the second time period with the first frequency value f1, and at the end of the second time period it ends with the first frequency value f1, in particular wherein the frequency value profile f(t) is continuous, in particular is continuous and can be differentiated continuously.