Rounded Sonotrode Geometry for Curved Panel Ultrasonic Welding

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Solution Overview

Problem

Existing sonotrodes cause excessive heating, are unsuitable for curved panels, require high energy density and power, and are cumbersome to set operational parameters for, leading to material distortion and porosity in thermoplastic composites.

Innovation Solution

A sonotrode with a rounded welding section approximating a circular sector or semi-cylindrical shape, allowing focused heat generation at the welding interface, suitable for curved materials, and enabling easier parameter determination through localized contact area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a flat sonotrode is used for welding, then the contact area is large, but the heating is excessive and the heat-affected zone is large

Engineering Contradiction:

Improveinterface temperatureVSAvoidcontact area

Core Design Contradiction:

TemperatureVSArea of stationary object

Solution Approach 1:

The sonotrode welding section is designed with a rounded shape (circular sector or semi-cylindrical) instead of a flat surface. This curvature concentrates the ultrasonic vibration energy and heat generation at a localized welding interface, reducing the overall heat-affected zone and preventing excessive heating of surrounding areas while maintaining effective welding capability.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Object-affected harmful factors

If a flat sonotrode is used, then the contact area is large, but the surrounding areas are heated up and through-the-thickness heating occurs

Engineering Contradiction:

Improveheating of surrounding areasVSAvoidcontact area

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The rounded welding section creates a localized contact area that focuses energy delivery precisely at the welding interface. This local concentration of energy minimizes heat diffusion to surrounding areas and prevents through-the-thickness heating, while still providing sufficient contact area for effective welding.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If a rounded sonotrode is used, then the heat generation is focused, but the contact area is reduced

Engineering Contradiction:

Improvewelding qualityVSAvoidcontact area

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The curved geometry of the welding section optimizes the contact characteristics by concentrating the ultrasonic vibration amplitude at the welding interface. This curvature design improves welding quality through better energy distribution while maintaining an adequate contact area for effective heat generation and material fusion.

Inventive Principle:

Principle #14Spheroidality (Curvature)

4Power

If conventional sonotrodes are used, then high power is required, but the energy density is excessive and material distortion occurs

Engineering Contradiction:

Improvepower requirementsVSAvoidmaterial distortion

Core Design Contradiction:

PowerVSManufacturing precision

Solution Approach 1:

The rounded welding section improves the distribution of ultrasonic vibration energy, reducing peak energy density at any single point. This curved geometry allows for more uniform heat generation across the welding interface, reducing the total power required while preventing excessive localized heating that causes material distortion and porosity.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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

Reduces power requirements, minimizes heating of surrounding areas, improves welding quality, and facilitates efficient welding of curved panels with reduced material distortion and porosity.

Implementation Method 1

a sonotrode may exert high frequency low peak-to-peak amplitude vibrations transversely to a welding interface

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

The vibrations may introduce surface and viscoelastic friction at the weld interface, which may heat up the welding interface

Methodology Applied

Scientific EffectViscoelastic friction: Friction

Implementation Method 3

continuous ultrasonic welding a sonotrode may exert high frequency low peak-to-peak amplitude vibrations transversely to a welding interface while applying a (constant) static pressure

Methodology Applied

Scientific EffectUltrasonic welding: Welding

Data Source

PatentUS12479168B2Rounded sonotrode

Publication Date: 2025.11.25 TECH UNIV DELFT

AI summary

The invention provides a sonotrode (100) for welding a material, the sonotrode (100) comprising a welding section (110) configured for contacting the material, wherein the welding section (110) defines a rounded shape (111) in a cross-section parallel to a longitudinal axis (A) of the sonotrode (100), wherein the rounded shape (111) approximates a circular sector (20), wherein the circular sector (20) has a central angle αc selected from the range of 25°-300°, and wherein the circular sector (20) has a central radius rc selected from the range of 5-30 mm, and wherein the sonotrode (100) has a width W perpendicular to the longitudinal axis (A) [and to the cross-section], wherein W is selected from the range of 10-100 mm.