Ultrasonic Weld-Bonding Thermoplastic Composites

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Solution Overview

Problem

Current ultrasonic welding techniques for polymeric materials result in undesirable variations in bond line thickness and joint strength due to adhesive migration during the welding process, requiring post-welding curing that prolongs cycle time and can weaken the workpieces.

Innovation Solution

The method involves using preformed deformations in thermoplastic polymer workpieces with an adhesive precursor, where the ultrasonic horn seats within the deformation to control bond line thickness, applying ultrasonic energy to create a weld nugget with green strength, and allowing the adhesive to react at ambient conditions, minimizing cycle time and adhesive degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If adhesive is applied between workpieces during ultrasonic welding, then bond strength is improved, but adhesive migration causes variation in bond line thickness and joint strength

Engineering Contradiction:

Improvebond strengthVSAvoidbond line thickness consistency

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The adhesive precursor is applied to the workpiece surface before ultrasonic welding, and the welding process itself activates the adhesive through frictional heat and pressure, eliminating the need for separate curing steps and preventing adhesive migration by controlling the bonding sequence

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The adhesive precursor undergoes chemical transformation from inactive to active state through the thermal and mechanical parameters generated during ultrasonic welding (frictional heat, pressure, vibration), enabling bond formation without external curing equipment

Inventive Principle:

Principle #35Parameter changes

2Strength

If post-welding curing is applied to ensure sufficient strength, then joint strength is improved, but cycle time increases and workpiece integrity deteriorates

Engineering Contradiction:

Improvejoint strengthVSAvoidcycle time

Core Design Contradiction:

StrengthVSLoss of time

Solution Approach 1:

The ultrasonic welding process and adhesive activation process are merged into a single operation, where the frictional heat and pressure generated during welding simultaneously activate the adhesive precursor, eliminating the need for separate post-welding curing steps

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The ultrasonic welding process itself provides the thermal and mechanical energy needed to activate the adhesive precursor, making the system self-sufficient without requiring external curing equipment or additional processing steps

Inventive Principle:

Principle #25Self-service

3Strength

If post-welding curing is applied to ensure sufficient strength, then joint strength is improved, but workpiece integrity deteriorates due to heat exposure

Engineering Contradiction:

Improvejoint strengthVSAvoidworkpiece weakening from heat

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The frictional heat generated during ultrasonic welding, which could potentially harm the workpiece, is converted into a beneficial effect by using it to activate the adhesive precursor and form the bond, eliminating the need for separate high-temperature curing processes

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 enables immediate further processing of assemblies with consistent bond line thickness and strength, reducing cycle time and adhesive degradation, while maintaining the integrity of the polymeric composites.

Implementation Method 1

applying ultrasonic energy from the ultrasonic horn to create a weld nugget between the first thermoplastic polymer workpiece and the second thermoplastic polymer workpiece

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

The vibration creates surface friction along interfacing surfaces and internal friction of the workpieces. Where the workpieces are formed of a polymeric or plastic material, the resultant heat softens the interfacing surfaces

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 3

At least one of the ultrasonic horn or the anvil seats within the preformed deformation to provide a predetermined bondline between the first thermoplastic polymer workpiece and the second thermoplastic polymer workpiece

Methodology Applied

Scientific EffectMechanical constraint:

Data Source

PatentUS11654636B2Ultrasonic weld-bonding of thermoplastic composites

Publication Date: 2023.05.23 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

Methods for ultrasonic welding of thermoplastic polymer workpieces and assemblies made therefrom are provided. The method may comprise disposing a first region of a first thermoplastic polymer workpiece and a second region of a second thermoplastic polymer workpiece between an ultrasonic horn and an anvil of an ultrasonic welding device. The first workpiece has a preformed deformation and at least one of the first and/or second workpieces has an adhesive precursor applied thereto. The ultrasonic horn or anvil seats within the preformed deformation. Ultrasonic energy is applied from the ultrasonic horn to create a weld nugget between the first and second workpieces. The assembly thus formed has a green strength sufficient to be further processed immediately. The methods provide a robust weld joint with controlled adhesive bondline thickness.