Variable-Cross-Section Sonotrode for Stable Ultrasonic Metal Welding

Solution Overview

Problem

Ultrasonic metal welding sonotrodes require frequent position changes to maintain high-quality welding results, leading to significant downtimes due to the need to re-determine parameters after a certain number of operations, which reduces efficiency and increases production costs.

Innovation Solution

The sonotrode head is designed with varying cross-sections along its working surface, where the cross-section is larger at the end region and smaller in the middle, optimizing the vibration behavior to minimize amplitude changes during position shifts, allowing for more operations without parameter re-determination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the sonotrode head has a constant cross-section along the working surface, then the manufacturing is simpler, but the vibration behavior causes amplitude changes when welding position is changed, requiring frequent parameter re-determination and causing downtimes

Engineering Contradiction:

Improvesonotrode head manufacturing simplicityVSAvoidwelding operations per unit time

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The sonotrode head is designed with varying cross-sectional dimensions along its length, creating different local properties. The cross-section is larger at the end region and smaller in the middle region, which optimizes the vibration behavior locally to minimize amplitude changes during position shifts, thereby reducing downtimes and increasing productivity

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The cross-sectional dimensions of the sonotrode head are varied along its length rather than remaining constant. This parameter change in the geometric configuration optimizes the vibration characteristics and amplitude distribution, allowing for more welding operations without parameter re-determination

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the welding position is changed after a certain number of operations, then the wear is evened out and sonotrode utilisation is maximized, but parameter re-determination is required causing downtimes

Engineering Contradiction:

Improvesonotrode utilisation and wear distributionVSAvoiddowntime for parameter re-determination

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The varying cross-section creates different local vibration characteristics along the sonotrode head, which helps maintain consistent welding quality across different positions. This allows the sonotrode to be used more extensively at each position before wear becomes an issue, reducing the frequency of position changes and associated downtimes

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of changing positions frequently to prevent wear, the invention inverts the approach by designing the sonotrode head geometry to maintain performance over longer usage periods at each position, thereby reducing the need for position changes and parameter re-determination

Inventive Principle:

Principle #13The other way round (Inversion)

3Manufacturing precision

If the sonotrode head cross-section is larger at the end region and smaller in the middle region, then the vibration behavior is optimized and amplitude changes are minimized, but the manufacturing complexity increases

Engineering Contradiction:

Improvewelding quality consistencyVSAvoidsonotrode head geometric complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The sonotrode head is designed with varying cross-sectional dimensions along its length, creating different local properties. The cross-section is larger at the end region and smaller in the middle region, which optimizes the vibration behavior locally to minimize amplitude changes during position shifts, thereby reducing downtimes and increasing productivity

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The cross-sectional dimensions of the sonotrode head are varied along its length rather than remaining constant. This parameter change in the geometric configuration optimizes the vibration characteristics and amplitude distribution, allowing for more welding operations without parameter re-determination

Inventive Principle:

Principle #35Parameter changes

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 design reduces downtimes and increases the number of welding operations per unit time by smoothing the vibration behavior, ensuring consistent quality without the need for frequent parameter adjustments.

Implementation Method 1

the sonotrode is coupled to the part to be joined facing it and moves it. Pressure is simultaneously applied. Welding together takes place through interaction of the static and dynamic forces

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

the mechanical vibrations are oriented parallel to the surface to be joined

Methodology Applied

Scientific EffectMechanical vibration: Vibration

Implementation Method 3

the cross-section of the sonotrode head is greater at the end region, extending at the end face, of the working surface than in the middle region of the working surface

Methodology Applied

Scientific EffectVibration optimization through geometric design:

Data Source

PatentUS11498152B2Sonotrode and method for influencing the vibratory behavior of a sonotrode

Publication Date: 2022.11.15 SCHUNK SONOSYST GMBH

AI summary

The invention relates to a sonotrode (218) of an ultrasonic welding device with a sonotrode body (224) with sonotrode head (220) with at least one working surface (230) extending in the longitudinal direction of the sonotrode head for welding or welding together and/or deforming and/or cutting at least one item of metallic welding material, wherein the sonotrode head has cross-sections which vary along the working surface in such a way that the cross-section of the sonotrode head in the end region of the working surface extending at the end face is greater than in the middle region of the working surface.