Beam Tool Focus Calibration Using Webbed Test Cuts

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Solution Overview

Problem

Current methods for determining the focus position in laser-based machine tools are often manual or prone to subjective errors, making them inefficient and unreliable for precise processing of workpieces.

Innovation Solution

A method involving a sequence of test cuts with varying focal positions along a disk-like area, where the reference focus position is determined by evaluating the cut structures and assigning it based on whether the workpiece has disks held by webs or openings, using a relative movement trajectory and automated evaluation to identify the optimal focus position for the highest power density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If manual measurement methods are used to determine focus position, then the setup process is simple, but the precision and reliability of focus position determination deteriorates

Engineering Contradiction:
Improvesimplicity of setup processVSAvoidprecision of focus position determination
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The system performs self-determination of the reference focus position by automatically evaluating cut structures produced during test cuts. The control unit autonomously analyzes the cut width measurements and identifies the optimal focus position without requiring manual measurement or subjective operator judgment, thereby achieving both automation and precision.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual measurement methods with an automated optical and computational system. Instead of manual measurement of cutting widths, the system uses automated detection of cut structures, numerical evaluation of cut widths, and algorithmic determination of the reference focus position, substituting mechanical/manual operations with automated sensing and computation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If automated test cuts are performed with multiple focal positions, then the precision of focus position determination improves, but the complexity of the device and process increases

Engineering Contradiction:
Improveprecision of focus position determinationVSAvoidcomplexity of test cut process
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the focus position determination process into distinct phases: performing multiple test cuts at different focal positions, measuring cut structures at each position, evaluating the measurements, and determining the reference focus position. This segmentation allows the complex process to be systematically managed and automated through control software.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system varies the focal position parameter across multiple test cuts to determine the optimal focus position. By systematically changing this parameter and measuring the corresponding cut structure characteristics, the system identifies the reference focus position that produces the desired cut quality, thereby managing complexity through controlled parameter variation.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If multiple test cuts are performed with varying focal positions, then the reliability of focus position determination improves, but the time required for setup increases

Engineering Contradiction:
Improvereliability of focus position determinationVSAvoidsetup time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary test cuts at multiple focal positions to establish the reference focus position before actual production work begins. This preliminary action ensures reliable focus position determination upfront, preventing time loss during production due to focus adjustments or quality issues.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from cut structure measurements to automatically determine the reference focus position. The control unit analyzes the cut width data from multiple test cuts and uses this feedback to identify the optimal focal position, thereby improving reliability while minimizing manual intervention time.

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

This approach allows for reproducible, precise, and automated determination of the focus position, reducing the probability of errors and simplifying the setup process, applicable to various laser types and power ratings, leading to improved cutting quality and efficiency.

Implementation Method 1

In beam-based, in particular laser-based, machine tools, an exact positioning of a focus position (e.g. of a laser or electron beam) is fundamental for the implementation of the precise processing of workpieces

Methodology Applied
Scientific EffectLaser beam: Laser

Implementation Method 2

it is necessary to bring the laser beam into contact with the workpiece at the point where it has the highest power density

Methodology Applied
Scientific EffectOptical energy concentration: Focusing

Data Source

PatentEP3475025B1Method and device for determining a reference focal position of a beam of a beam-based machine tool by performing a sequence of test cuts on a workpiece
Publication Date: 2021.07.28 TRUMPF LASER & SYSTEMTECHNIK GMBH
  • EP3475025B1 patent drawingFigure 1~2
  • EP3475025B1 patent drawingFigure 3~4
  • EP3475025B1 patent drawingFigure 5A~7

AI summary

The invention relates to a method and a machine tool for determining a reference focal position (35) of a beam of a beam-based machine tool. Said method comprises the following steps: providing a relative movement trajectory which defines a discoid region with respect to a surrounding area, wherein said discoid region is connected to the surrounding area via at least one web region, and performing a sequence of test cuts on a workpiece (5), wherein a cutting structure is cut in each test section in the workpiece (5) by guiding the beam (37) along the relative movement trajectory and the cut is carried out along the at least one web region of the relative movement trajectory in differently adjusted focal positions.