Ultrasonic Spot Welding With Indentation-Depth Feedback Control
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Solution Overview
Problem
Ultrasonic spot welding processes face challenges in achieving consistent high-quality weld joints across varying locations and geometries due to material and structural dependencies, leading to inconsistent joint strengths in joining lightweight materials like aluminum and magnesium alloys.
Innovation Solution
The method involves indentation-depth control in ultrasonic spot welding, where a sonotrode is brought into contact with a workpiece, and high-frequency vibrations are applied until a predetermined downward displacement is reached, at which point the power is terminated, ensuring consistent indentation depths and improved joint quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ultrasonic spot welding uses predetermined welding energy parameters, then the welding process is simple and fast, but the joint strength varies significantly across different locations and geometries
Solution Approach 1:
The patent implements feedback control by measuring the actual downward displacement of the sonotrode during welding and using this measurement to terminate the welding process. The controller continuously monitors displacement and compares it to the target value, automatically stopping the process when the target is reached, ensuring consistent joint strength across different locations and geometries.
Solution Approach 2:
The patent replaces the conventional energy-based control system with a displacement-based control system. Instead of relying on predetermined welding energy parameters that vary with geometry, the system uses direct measurement of sonotrode displacement to control the welding process, substituting mechanical measurement for energy-based control.
2Reliability
If ultrasonic spot welding applies constant welding energy to different geometries, then the process is efficient and quick, but the weld quality becomes inconsistent
Solution Approach 1:
The patent implements dynamic control of the welding process by continuously monitoring sonotrode displacement in real-time and adjusting the welding termination point based on actual measured values. This dynamic adjustment allows the process to adapt to different geometries and locations while maintaining consistent weld quality, eliminating the need for geometry-specific parameter tuning.
Solution Approach 2:
The patent changes the control parameter from predetermined welding energy to measured downward displacement. By using displacement as the controlling parameter and setting a universal target displacement value that works across different geometries, the system achieves consistent weld quality without sacrificing productivity, as the process automatically adapts to each weld location.
3Adaptability or versatility
If conventional methods use predetermined welding parameters, then the setup is simple, but the process cannot adapt to different joint locations and part geometries
Solution Approach 1:
The welding system performs self-adjustment by automatically measuring its own sonotrode displacement during the welding process and using this self-measured data to control termination. This self-service capability eliminates the need for external geometry-specific programming or complex setup procedures, allowing the system to adapt to different geometries while keeping the control system relatively simple.
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 consistently achieves strong lap joints with superior lap shear strength, independent of joint locations or part geometry, significantly improving the consistency and quality of welds compared to conventional methods.
Implementation Method 1
applying an electrical current to a transducer to generate high-frequency vibrations
Implementation Method 2
frictional heat at a faying joint interface between the upper workpiece and a lower workpiece
Implementation Method 3
as the weld area softens and the surface indentation increases
Data Source
AI summary
An improved method for friction pressure welding via indentation-depth control is provided. The method includes: (a) bringing a sonotrode into contact with an upper workpiece with a clamping force; (b) recording the sonotrode position as a reference when in contact with the upper workpiece; (c) applying an electrical current to a transducer to generate high-frequency vibrations and frictional heat at a faying joint interface; (d) measuring a downward displacement of the sonotrode as the weld area softens and the surface indentation increases; and (e) terminating the electrical current to the transducer and retracting the sonotrode from the upper workpiece in response to a predetermined downward displacement of the sonotrode (indentation depth). The method of the present invention can achieve quality joints independent of joint locations, part geometry, or fixture conditions.