Laser Welding Scattering Layer for Layered Products

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Solution Overview

Problem

In laser welding processes, radiation can inadvertently affect non-intended absorbing layers, particularly in layered products like ostomy bags, where one layer is attached to another, causing unintended heating or damage during the welding process.

Innovation Solution

A method involving a scattering material with a high scattering coefficient is placed between the layers to redirect and diffuse the radiation, ensuring that the intended layer absorbs the majority of the radiation for welding while minimizing exposure to the non-intended layer, thereby preventing excessive heating or damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If radiation is transmitted through the first layer to weld the first layer to the second element, then welding strength is improved, but the second layer may be adversely affected by excessive radiation exposure

Engineering Contradiction:

Improvewelding strengthVSAvoidradiation exposure to second layer

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

A third layer with high scattering coefficient is introduced as an intermediary between the first and second layers. This scattering layer redirects radiation that has penetrated the first layer, preventing it from reaching the second layer in excessive amounts. The scattering layer acts as a mediator that allows the welding process to proceed effectively while protecting the second layer from harmful radiation exposure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If higher radiation intensity is used to ensure strong welds, then welding quality is improved, but the risk of overheating and damaging the second layer increases

Engineering Contradiction:

Improvewelding qualityVSAvoidtemperature of second layer

Core Design Contradiction:

Manufacturing precisionVSTemperature

Solution Approach 1:

The third scattering layer serves as a thermal buffer by redirecting excess radiation before it reaches the second layer. This intermediary structure allows higher radiation intensities to be used for improved welding quality while the scattering layer absorbs and redistributes the excess energy, preventing localized overheating and thermal damage to the second layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If the first layer has high absorption coefficient to enable effective laser welding, then welding efficiency is improved, but more radiation is transmitted through to the second layer

Engineering Contradiction:

Improvewelding efficiencyVSAvoidradiation transmission to second layer

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The third layer with high scattering coefficient compensates for the high absorption coefficient of the first layer. While the first layer efficiently absorbs laser energy for productive welding, the third scattering layer intercepts and redirects the radiation that would otherwise transmit through to the second layer, thus decoupling the welding efficiency from the harmful radiation transmission.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Different layers are assigned different optical properties optimized for their specific functions: the first layer has high absorption coefficient for efficient energy uptake at the welding interface, while the third layer has high scattering coefficient to redirect transmitted radiation. This local differentiation of material properties allows each layer to perform its specific function optimally without compromising the others.

Inventive Principle:

Principle #3Local quality

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 effectively reduces the intensity of radiation reaching the non-intended layer, ensuring strong welds are formed without damaging the surrounding material, even at lower radiation energies, and prevents overheating, thus improving the reliability and safety of the laser welding process.

Implementation Method 1

providing a third layer having a scattering coefficient, μs>0.4 mm−1, at the wavelength, between the first and second layers, in the direction of the radiation... radiation having penetrated the first layer being scattered by the third layer

Methodology Applied

Scientific EffectScattering: Scattering

Implementation Method 2

the first layer having a first absorption coefficient, μa1>0.4 mm−1, at a wavelength of the radiation... heating the first layer so as to weld the first layer to the second element

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentUS8872069B2Method of providing a laser welded product and a laser welded product

Publication Date: 2014.10.28 COLOPLAST AS

AI summary

A method of laser welding a layered product comprising two layers (44, 46) of a high absorption at the radiation wavelength, where one layer (44) is welded to a material (42) having a lower absorption and wherein a scattering layer (48) is provided between the laser welded layers (42, 44) and the other high absorption layer (48) in order to scatter any radiation penetrating the first high absorption layer (44) in order to prevent excessive heating of the other high absorption layer (46).