Laser Machining Head Focal Point Compensation for Lateral Accuracy

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Solution Overview

Problem

Modern laser-beam machining heads face challenges in maintaining precise focal point positioning due to mechanical and thermal errors, manufacturing tolerances, and varying nozzle geometries, leading to reproducible positional errors that are costly to correct.

Innovation Solution

A method that records the influence of movable laser machine components on focal point position before machining and adjusts optical elements during the process to set the focal point to a preset position, using stored correction values to compensate for errors, allowing for less stringent manufacturing tolerances and reduced operational costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high precision manufacturing is used for laser-beam machining heads to minimize lateral positional errors, then manufacturing precision is improved, but manufacturing cost increases

Engineering Contradiction:

Improvelateral positional accuracy of laser-beam focal pointVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by measuring and storing the actual lateral positions of optical elements and the focal point before machining operations begin. This pre-measurement data is then used to calculate correction values that compensate for manufacturing tolerances and thermal deformations, eliminating the need for expensive high-precision manufacturing while maintaining accurate focal point positioning.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If optical elements are designed with high precision to minimize thermal deformation effects, then reliability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvefocal point position stability under thermal conditionsVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent implements feedback by continuously measuring the actual positions of optical elements and the focal point during operation, comparing these measurements against target positions, and automatically adjusting the beam path or optical element positions to compensate for thermal deformations. This feedback mechanism maintains reliable focal point positioning despite using standard-precision components subject to thermal effects.

Inventive Principle:

Principle #23Feedback

3Manufacturing precision

If manual lateral adjustment mechanisms are added to compensate for positional errors, then focal point positioning accuracy is improved, but device complexity increases

Engineering Contradiction:

Improvelateral adjustment capability of focal pointVSAvoidcomplexity of adjustment mechanisms

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical adjustment mechanisms with a computational approach. Instead of adding manual lateral adjustment mechanisms, the system measures actual positions, calculates correction values computationally, and applies these corrections through controlled adjustments of optical elements or beam path, eliminating the need for complex manual adjustment hardware while achieving the same positioning accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method enables reproducible and accurate lateral positioning of the laser-beam focal point, reducing the need for high absolute accuracy in manufacturing and allowing for quick compensation of mechanical tolerances, thereby minimizing damage to tools and workpieces.

Implementation Method 1

During operation, the optical elements (lenses, mirrors, mechanical receptacles) in the machining head heat up as a result of the large laser power introduced

Methodology Applied

Scientific EffectThermal heating: Heating

Implementation Method 2

and can thermally deform as a result of alternately heating and cooling

Methodology Applied

Scientific EffectThermal deformation: Thermal Expansion

Data Source

PatentUS11612954B2Laser-beam material machining

Publication Date: 2023.03.28 TRUMPF WERKZEUGMASCHINEN GMBH & CO KG

AI summary

A method performed by a laser machine includes: before a laser-beam machining process, recording an influence of a change in a position of at least one movable laser machine component on a lateral position of a focal point of a laser beam in a focal plane or relative to a reference point, storing an association between the position of the movable laser machine component and the lateral position, and then, setting, based on the stored association, the focal point to a preset lateral position in the focal plane or relative to the reference point by setting the position of the movable laser machine component. The movable laser machine component can include at least one of at least one optical element in a beam path of the laser beam, a laser-beam machining head in a work area of a laser machine, or a movable part of the laser-beam machining head.