Additively Manufactured Sonotrode for Resonance Without Tuning
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Solution Overview
Problem
Traditional ultrasonic welding horns require individual tuning after machining to ensure resonance at the desired frequency, leading to inefficiencies and potential damage due to near-resonance modes, as they are not repeatable part-to-part.
Innovation Solution
A sonotrode manufactured using direct metal laser sintering with multiple layers of material, featuring a substantial unmachined outer surface and internal cavities, providing a monolithic construction and integrated cooling passages, which allows for precise control of density and frequency, eliminating the need for post-machining tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional machining methods are used to manufacture sonotrodes, then manufacturing precision can be achieved, but individual tuning is required for each part resulting in loss of time and reduced productivity
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-configuring the sonotrode geometry during the additive manufacturing process to achieve the desired resonant frequency. The build orientation, layer thickness, and infill patterns are predetermined to produce the exact frequency characteristics needed, eliminating the need for post-manufacturing tuning operations.
Solution Approach 2:
The patent utilizes parameter changes by varying the additive manufacturing parameters (layer thickness, infill density, build orientation, heating power) to precisely control the sonotrode's mass distribution and stiffness characteristics. These parameter adjustments during manufacturing directly tune the resonant frequency without requiring subsequent machining or adjustment operations.
2Measurement precision
If individual tuning is performed on each sonotrode after machining, then frequency accuracy is improved, but the process becomes time-consuming and reduces manufacturing productivity
Solution Approach 1:
The patent eliminates post-manufacturing tuning by performing all necessary frequency adjustments during the additive manufacturing process itself. The resonant frequency is predetermined and embedded into the part geometry through controlled deposition parameters, ensuring each sonotrode is frequency-accurate upon completion without requiring additional tuning time.
3Ease of manufacture
If near-resonance modes are excited in traditionally manufactured sonotrodes, then manufacturing is simpler, but the sonotrode may fail to achieve sufficient displacement and compromise weld quality
Solution Approach 1:
The patent applies local quality by creating non-uniform density distributions within the sonotrode structure through varied infill patterns and layer densities in specific regions. This local variation in material properties allows precise control over the modal characteristics, ensuring the fundamental longitudinal mode is strongly excited while suppressing near-resonance modes that could compromise weld quality.
4Ease of manufacture
If traditional subtractive machining is used, then material removal is straightforward, but significant material is lost and manufacturing cost increases
Solution Approach 1:
The patent inverts the traditional manufacturing approach by using additive manufacturing instead of subtractive machining. Rather than starting with a solid block and removing material to achieve the desired geometry, the sonotrode is built layer-by-layer only where material is needed, fundamentally eliminating material waste while maintaining manufacturing simplicity through automated deposition processes.
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 sonotrode achieves repeatable resonant frequencies within 0.25-0.75% of the desired design frequency, reducing the need for individual tuning and enhancing weld quality and durability by avoiding near-resonance modes.
Implementation Method 1
A sonotrode manufactured using direct metal laser sintering with multiple layers of material
Implementation Method 2
The sonotrode is designed to resonate at a longitudinal mode, which induces a particular displacement at the sonotrode tip used to generate heat and weld the workpiece
Implementation Method 3
A converter having a piezoelectric stack that selectively vibrates in response to power from a generator
Implementation Method 4
the sonotrode is designed to resonate at a longitudinal mode, which induces a particular displacement at the sonotrode tip used to generate heat and weld the workpiece
Data Source
AI summary
A sonotrode includes multiple layers of a material melted to one another to form a structure. The structure provides a base that has an attachment feature that is configured to operatively secure to an ultrasonic converter. The structure includes a shaft that extends from the base to a terminal end that provides a working surface that is configured to selectively engage a workpiece. The structure has at least one shaft that includes a first shaft that extends from the base to a first terminal end that provides a first working surface that is configured to selectively engage a workpiece. The first shaft is integrally formed with the base from the multiple layers to provide an unbroken, monolithic construction.