Laser Focal Offset Learning for Heat-Drift Correction

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Solution Overview

Problem

Laser processing apparatuses face challenges in accurately correcting focal position offsets due to disturbances like heat, leading to deviations in the effective light-focusing position, which affect the quality of processing and the lifespan of optical system components.

Innovation Solution

A machine learning device and method that learn the positional relationship between a workpiece and the effective light-focusing position by generating a learning model from data on focal position commands and light detection data, enabling precise correction of focal position offsets during processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional focal position correction methods are used, then the focal position can be adjusted, but the precision of correction is insufficient due to disturbances like heat

Engineering Contradiction:
Improvefocal position offset correction precisionVSAvoidstability of effective light-focusing position
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The system performs preliminary learning to establish the relationship between light detector output values and focal position offsets before actual processing. By pre-acquiring correction data under various conditions (including heat disturbances), the system can apply accurate corrections without real-time measurement delays, improving both precision and reliability

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses light detectors to continuously monitor the actual focal position and feeds this information back to the correction mechanism. The light detector output values are compared against the learned relationship model, and real-time feedback enables dynamic adjustment of the focal position to compensate for heat-induced drift and other disturbances

Inventive Principle:
Principle #23Feedback

2Productivity

If the light-focusing optical system is used for processing, then workpiece processing can be performed, but the effective light-focusing position deviates from the designed focal position due to heat and other disturbances

Engineering Contradiction:
Improveworkpiece processing capabilityVSAvoidpositional relationship between workpiece and effective light-focusing position
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent introduces light detectors as intermediary elements that indirectly measure the focal position by detecting the position of the focused laser beam. This intermediary measurement approach allows for precise focal position monitoring without interfering with the actual workpiece processing, enabling continuous correction while maintaining productivity

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system performs preliminary learning to establish the relationship between light detector output values and focal position offsets before actual processing. By pre-acquiring correction data under various conditions (including heat disturbances), the system can apply accurate corrections without real-time measurement delays, improving both precision and reliability

Inventive Principle:
Principle #10Preliminary action

3Duration of action of moving object

If the focal position is not corrected, then processing can continue, but the quality of laser processing deteriorates

Engineering Contradiction:
Improvecontinuous processing capabilityVSAvoidprocessing quality
Core Design Contradiction:
Duration of action of moving objectVSManufacturing precision

Solution Approach 1:

The system implements continuous focal position monitoring and correction during the entire processing operation. Light detectors continuously track focal position drift, and the correction mechanism continuously adjusts the focal position to maintain optimal processing quality throughout extended production runs, enabling both continuous operation and consistent quality

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The system uses light detectors to continuously monitor the actual focal position and feeds this information back to the correction mechanism. The light detector output values are compared against the learned relationship model, and real-time feedback enables dynamic adjustment of the focal position to compensate for heat-induced drift and other disturbances

Inventive Principle:
Principle #23Feedback

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

Improves the precision of focal position offset correction, maintains processing quality, and extends the lifespan of light-focusing optical system components by adapting to variations in processing conditions and workpiece characteristics.

Implementation Method 1

a light-focusing optical system including a lens, a mirror, a protective window, etc.

Methodology Applied
Scientific EffectOptical focusing: Focusing

Implementation Method 2

detection data of a physical quantity of light detected when a laser beam is emitted

Methodology Applied
Scientific EffectLight detection: Photoelectric Effect

Data Source

PatentUS11565344B2Device and method for learning focal position offset of laser processing apparatus, and laser processing system correcting focal position offset
Publication Date: 2023.01.31 FANUC LTD
  • US11565344B2 patent drawing
  • US11565344B2 patent drawing
  • US11565344B2 patent drawing

AI summary

A machine learning device for learning a focal position offset of a laser processing apparatus. A data acquisition section acquires a learning dataset which includes data of a focal position command for a light-focusing optical system given to the laser processing apparatus and detection data of a physical quantity of light detected when a laser beam is emitted from a laser oscillator in accordance with a processing command including the focal position command. A learning section generates a learning model by using the learning dataset, which represents correlativity between the physical quantity of the detected light and the positional relationship of an effective light-focusing position of the light-focusing optical system relative to a workpiece. When performing processing, the physical quantity of light is detected so that a positional relationship between the workpiece and the effective light-focusing position during processing can be estimated from the detected quantity and the learning model.