Laser Cutting Monitoring via Oblique Imaging of the Cutting Front

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Solution Overview

Problem

Existing cutting processes face challenges in reliably determining the cutting front angle during laser cutting, particularly due to issues like the elongation of the emitting region caused by dripping melt filaments, which hinders accurate measurement and leads to process irregularities and loss of cut.

Innovation Solution

A device that focuses a high-energy beam onto a workpiece, using an image capture apparatus to observe the interaction region at an angle to the beam axis, allowing for the determination of characteristic variables like the cutting front angle through imaging optics and a control apparatus that adjusts the observation direction to maintain alignment with the cutting process, enabling closed-loop control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If coaxial observation of the interaction region is used, then the measurement setup is simple, but the cutting front angle cannot be reliably determined due to elongation of the emitting region by dripping melt filaments

Engineering Contradiction:

Improvemeasurement setup complexityVSAvoidcutting front angle measurement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent transitions from coaxial observation (one-dimensional alignment along beam axis) to oblique observation (introducing a second dimension by observing at an angle). This dimensional change allows the observation beam to intersect the cutting front at an optimal angle, enabling accurate measurement of the cutting front angle while avoiding the elongation effect caused by coaxial observation of dripping melt filaments.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Measurement precision

If observation angle is increased to improve cutting front angle measurement, then measurement accuracy improves, but the observation may be blocked by the workpiece upper side

Engineering Contradiction:

Improvecutting front angle measurement precisionVSAvoidobservation blockage by workpiece

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent implements dynamic adjustment of the observation angle based on real-time cutting conditions. The control apparatus continuously monitors the cutting process and adapts the observation angle to maintain optimal measurement conditions while avoiding blockage by the workpiece upper side. This dynamic approach allows the system to navigate between conflicting requirements of measurement accuracy and observation accessibility.

Inventive Principle:

Principle #15Dynamics

3Productivity

If cutting speed is increased to improve productivity, then productivity increases, but the cutting front angle may exceed critical values leading to loss of cut

Engineering Contradiction:

Improvecutting speedVSAvoidcut completion reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements a closed-loop feedback control system where the observed cutting front angle is continuously fed back to the control apparatus. Based on this feedback, the system automatically adjusts cutting parameters including cutting speed to maintain the cutting front angle within critical limits. This feedback mechanism enables the system to operate at high speeds while preventing loss of cut by dynamically adapting to changing cutting conditions.

Inventive Principle:

Principle #23Feedback

4Manufacturing precision

If laser power is increased to maintain cutting quality, then cutting quality improves, but energy consumption increases

Engineering Contradiction:

Improvecutting qualityVSAvoidlaser energy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent employs periodic modulation of laser power combined with dynamic adjustment based on real-time cutting front angle measurement. Rather than maintaining constant high power, the system uses periodic pulses and adapts power levels to actual cutting conditions, achieving high cutting quality while reducing overall energy consumption through intelligent power management.

Inventive Principle:

Principle #19Periodic action

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 reliable determination of cutting front angles and other characteristic variables, preventing loss of cut and improving cutting quality by adjusting parameters such as advance speed and laser power, thereby increasing productivity and process capability.

Implementation Method 1

a device for monitoring, and in particular for regulating, a cutting process on a workpiece... focusing a high-energy beam onto the workpiece

Methodology Applied

Scientific EffectLaser: Laser

Implementation Method 2

observing the temperature radiation emanating from the interaction region

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentUS11440141B2Devices and methods for monitoring, in particular for regulating, a cutting process

Publication Date: 2022.09.13 TRUMPF WERKZEUGMASCHINEN GMBH & CO KG

AI summary

The invention relates to devices and methods for monitoring or regulating a cutting process on a workpiece. A focusing element focuses a high-energy beam onto the workpiece. An image capture apparatus captures a region at the workpiece to be monitored. The region includes an interaction region of the high-energy beam with the workpiece. An control apparatus determines at least one characteristic variable of the cutting process, in particular of a kerf formed during the cutting process, on the basis of the captured interaction region.