Lamination Molding Apparatus Optical Abnormality Detection

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Solution Overview

Problem

Existing lamination molding apparatuses face challenges in accurately detecting optical system abnormalities, such as focus shifts, due to thermal lens effects caused by contamination of optical components like the chamber window, which can lead to suboptimal quality of three-dimensional molded objects.

Innovation Solution

A lamination molding apparatus equipped with a measuring unit comprising first and second photodetectors to measure light intensity and beam diameter, and a controller to determine abnormalities by analyzing the slope of linear functions derived from these measurements, allowing for more precise detection of focus shifts and contamination in the optical system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the chamber window is monitored to detect contamination, then the detection of focus shift due to thermal lens effect is improved, but other optical components experiencing the same issue cannot be detected

Engineering Contradiction:

Improvefocus shift detection accuracyVSAvoiddetection coverage of optical components

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent applies universality by making the detection system applicable to multiple optical components (chamber window, lenses, mirrors) rather than being limited to a single component. The detection method using photodetectors and linear function analysis can be universally applied to monitor any optical component in the laser path for contamination-induced focus shifts.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Object-affected harmful factors

If a fume diffuser is used to prevent fume adhesion to the chamber window, then contamination is reduced, but the thermal lens effect and focus shift cannot be completely eliminated

Engineering Contradiction:

Improvefume adhesion to chamber windowVSAvoidfocus position stability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent implements feedback by continuously monitoring the laser beam characteristics (beam diameter, light intensity) using photodetectors and comparing them against reference values. When deviations indicating focus shift are detected, the system can trigger corrective actions such as adjusting the focal position or alerting operators to clean contaminated optical components.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces the mechanical/physical protection approach (fume diffuser) with an optical detection and control system. Instead of relying solely on physical barriers to prevent contamination, the system uses optical measurements and electronic control to detect and compensate for focus shifts caused by thermal lens effects.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If the chamber window is replaced when deviation reaches a threshold, then the chamber window remains clean, but other contaminated optical components are not addressed

Engineering Contradiction:

Improvemolded object qualityVSAvoidcomprehensive optical system monitoring

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The detection system is designed to monitor multiple optical components throughout the laser path, not just the chamber window. By placing photodetectors at strategic positions and analyzing beam characteristics, the system can detect contamination and focus shifts in any optical component including lenses, mirrors, and the chamber window.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution enables more accurate recognition and correction of optical system abnormalities during the molding process, ensuring the production of three-dimensional molded objects with improved quality by identifying and addressing focus shifts and contamination issues in real-time.

Implementation Method 1

a first photodetector acquiring a measured value of the light intensity at a light detecting position of the laser beam

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

a second photodetector acquiring a value of a beam diameter at a light detecting position of the laser beam

Methodology Applied

Scientific EffectLight: Light

Implementation Method 3

a laser source which outputs a laser beam based on a set value of a light intensity

Methodology Applied

Scientific EffectLaser: Laser

Data Source

PatentUS11571750B2Lamination molding apparatus and method for producing three-dimensional molded object

Publication Date: 2023.02.07 SODICK CO LTD

AI summary

A lamination molding apparatus includes a molding room, a chamber, a chamber window, a molding table, a molding table driving device, surrounding walls, an irradiation device, a measuring unit, and a controller. The measuring unit includes a first measuring device acquiring a measured value of a light intensity, and a second measuring device acquiring a value of a beam diameter, and measures laser beams outputted based on set values of light intensity during molding. The controller determines an abnormality has occurred when a slope of a linear function obtained from a relationship between the measured value of the light intensity and the value of the beam diameter at a predetermined height is out of a predetermined range, or when a slope of a linear function obtained from a relationship between the measured value of the light intensity and a value of a focal position is out of a predetermined range.