Sonotrode Carrier Interface Roughening to Prevent Welding Twist

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Solution Overview

Problem

Ultrasonic welding devices face issues with the attachment of sonotrodes to sonotrode carriers, where deviations in tightening torque, contamination, and manufacturing flaws can lead to inadequate clamping force, causing twisting or deformation of the sonotrode, potentially resulting in damage during welding operations.

Innovation Solution

The solution involves roughening specific sections of the contact surfaces between the sonotrode and the sonotrode carrier to increase friction, creating a micro-toothing effect that enhances the secure connection without increasing the clamping force, thereby stabilizing the attachment and preventing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the sonotrode is attached to the sonotrode carrier using screws with clamping force, then the sonotrode is secured to the carrier, but the connection is sensitive to contamination, tightening torque deviations, and manufacturing flaws that can cause twisting or deformation

Engineering Contradiction:
Improveattachment reliabilityVSAvoidsensitivity to contamination and torque deviations
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the screw-based mechanical fastening system with a friction-based attachment system. The roughened contact surfaces create high friction that secures the sonotrode to the carrier without requiring screws, thereby eliminating sensitivity to tightening torque deviations and reducing contamination risks associated with threaded connections.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the surface parameter of the contact surfaces by roughening them to increase friction. This parameter change (surface roughness) transforms the attachment mechanism from one dependent on precise mechanical fastening to one dependent on friction, making the connection more robust against contamination and manufacturing variations.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If the clamping force is increased to prevent sonotrode twisting, then the attachment stability improves, but the risk of sonotrode breakage and deformation increases

Engineering Contradiction:
Improveattachment stabilityVSAvoidsonotrode strength
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The patent changes the friction parameter by roughening the contact surfaces, which allows achieving high attachment stability without increasing clamping force. The increased surface roughness creates higher friction coefficients, enabling the sonotrode to resist twisting forces while maintaining lower clamping forces that do not deform or break the sonotrode.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If the contact surfaces are made smooth for easy manufacturing, then the manufacturing precision is good, but the friction between surfaces is insufficient leading to inadequate attachment security

Engineering Contradiction:
Improvecontact surface manufacturingVSAvoidattachment security
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent deliberately changes the surface roughness parameter to enhance attachment security. By roughening the contact surfaces through machining or other surface treatment processes, the patent creates high-friction interfaces that securely attach the sonotrode to the carrier, accepting the additional manufacturing step as necessary for achieving reliable attachment.

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 approach significantly increases the torsional force required to twist the sonotrode, more than doubling the stability of the fastening while maintaining unobtrusive vibration, ensuring a secure and reliable connection during welding.

Implementation Method 1

At least one of the contact surfaces is roughened, at least in sections... appropriately increasing the friction between the sonotrode and the sonotrode carrier by deliberately roughening one or both contact surfaces

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4392198B1Ultrasonic welding device with a sonotrode carrier and a sonotrode attached to it
Publication Date: 2024.12.04 SCHUNK SONOSYST GMBH
  • EP4392198B1 patent drawingFigure 1
  • EP4392198B1 patent drawingFigure 2~3
  • EP4392198B1 patent drawingFigure 4~5

AI summary

An ultrasonic welding device (1) comprises a sonotrode (3) and a sonotrode carrier (2) designed to set the sonotrode (3) in ultrasonic vibrations. The sonotrode (3) and the sonotrode carrier (2) each have a contact surface (5), and at least some of one of the contact surfaces (5) is roughened. The sonotrode (3) is replaceably fastened to the sonotrode carrier (2) in such a way that the contact surfaces (5) are pressed against one another.