CW UV LED Curing for Selective Deposition Modeling

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Solution Overview

Problem

Existing Solid Freeform Fabrication (SFF) techniques face challenges with oxygen inhibition and high heat generation in selective deposition modeling (SDM) processes using UV-curable materials, leading to inefficient curing and apparatus complexity.

Innovation Solution

A continuous-wave (CW) UV curing system utilizing UV LEDs that emit UV radiation without infrared (IR) radiation, providing controlled exposure to cure UV-curable materials in a layerwise manner, reducing oxygen inhibition and heat generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional UV curing systems (mercury-halide lamps, metal halide lamps, or mercury-xenon lamps) are used to cure photopolymers in SDM, then effective polymerization can be achieved, but high levels of heat are generated and power consumption is substantial

Engineering Contradiction:

Improvecuring effectivenessVSAvoidheat generation

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent extracts and removes the harmful infrared radiation component from the UV curing system by using LEDs that emit only in the UV spectrum (380-420nm), eliminating the IR heat generation inherent in conventional mercury-halide and metal halide lamps while maintaining effective UV curing capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the thermal-mechanical curing system (conventional lamps that generate heat) with a cold optical curing system (UV LEDs), substituting the mechanism of heat-based curing with direct UV photon-based polymerization initiation, thereby eliminating the heat generation problem

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If continuous-running UV lamps are used to provide planar exposure for curing, then polymerization can be initiated, but the lamps consume significant power and require constant operation with long warm-up times

Engineering Contradiction:

Improvecuring capabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic action by using UV LEDs that can be rapidly switched on and off as needed, eliminating the need for continuous operation and long warm-up times required by conventional lamps, thereby dramatically reducing power consumption while maintaining curing capability when needed

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent employs short-lived UV LED units that can be activated only when curing is required, replacing the expensive continuous-operation conventional lamps, thereby reducing energy waste and operational costs

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If broad planar flood exposure to UV radiation is used to initiate curing in dispensed layers, then curing can be achieved, but oxygen inhibition significantly reduces or prevents polymerization

Engineering Contradiction:

Improvecuring initiationVSAvoidoxygen inhibition

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the spectral parameters of the UV radiation source to match the absorption characteristics of the photoinitiators in the curable material, using UV LEDs emitting at 380-420nm which corresponds to the absorption peak of common photoinitiators, thereby achieving effective curing with reduced oxygen inhibition through optimized wavelength selection

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

The CW UV curing system effectively initiates polymerization with reduced oxygen inhibition and heat, enabling efficient layer-by-layer building of three-dimensional objects while minimizing power consumption and apparatus complexity.

Implementation Method 1

A continuous-wave (CW) UV curing system utilizing UV LEDs that emit UV radiation

Methodology Applied

Scientific EffectLight-emitting diode (LED): Light Emitting Diode

Implementation Method 2

These curable materials generally contain photoinitiators and photopolymers which, when exposed to ultraviolet radiation (UV), begin to cross-link and solidify

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentUS8876513B2Selective deposition modeling using CW UV LED curing

Publication Date: 2014.11.04 3D SYSTEMS INC

AI summary

A continuous-wave (CW) ultraviolet (UV) curing system for solid freeform fabrication (SFF) is provided, wherein the curing system is configured to provide an exposure of UV radiation for one or more layers of UV-curable material. One or more UV exposures may initiate curing of a curable material in the layer dispensed by a solid freeform fabrication apparatus. One approach to provide the single or multiple UV exposures is the use of one or more UV LEDs, which generate UV radiation without generating any substantial amounts of infrared (IR) radiation at the same time. This allows for the curing process to be energy efficient and also allows for the SFF system to be far less complex.