Laser Cutting Head Distance Sensing for Moving Sheet Strip Blanks

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Solution Overview

Problem

Existing methods for cutting sheet metal blanks from continuously conveyed sheet metal strips are inefficient due to the need to switch off distance sensors and raise the laser cutting head, limiting the ability to cut from the strip edge to the inside and resulting in longer travel distances and increased processing time.

Innovation Solution

A method and device utilizing a laser cutting device with a rotatable distance sensor that remains in overlap with the sheet metal strip, allowing continuous distance measurement and control of the cutting nozzle's position, enabling cutting paths from the outside to the inside of the strip and optimizing cutting parameters for different thicknesses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the laser cutting head is raised and distance sensor system is switched off before reaching the strip edge, then collision with the sensor is avoided, but processing time increases and cutting effectiveness decreases

Engineering Contradiction:
Improvecollision avoidanceVSAvoidprocessing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

A capacitive sensor field is introduced as an intermediary detection mechanism that extends beyond the physical cutting nozzle. This sensor field detects the strip edge and blank rise/fall conditions before the cutting nozzle reaches them, enabling early warning and preventive control actions without requiring the cutting head to raise or the distance sensor system to switch off

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The capacitive sensor provides continuous feedback about the distance to the strip edge and blank position changes. This feedback is processed by the control system to dynamically adjust cutting parameters and nozzle position in real-time, eliminating the need for pre-programmed raise/lower sequences and sensor switching

Inventive Principle:
Principle #23Feedback

2Ease of manufacture

If the cutting path starts from the inside of the strip to the edge, then the existing sensor system can be used, but the blank may rise or fall causing collision and requiring sensor switch-off

Engineering Contradiction:
Improvecutting path implementationVSAvoidcollision risk
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The capacitive sensor field acts as an intermediary that detects strip edge and blank position changes earlier than the cutting nozzle would encounter them. This early detection enables the control system to manage blank stability and prevent collisions throughout the entire cutting path from inside to edge

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If the distance sensor system remains on during cutting from edge to inside, then continuous measurement is possible, but the sensor may collide with the rising or falling blank

Engineering Contradiction:
Improvedistance measurement continuityVSAvoidsensor collision risk
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The capacitive sensor field serves as an intermediary detection system that monitors blank position and strip edge conditions without being vulnerable to collision. Since the capacitive field extends beyond the physical nozzle position, it can detect issues before they affect the cutting nozzle or distance sensor system

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The capacitive sensor provides continuous feedback about blank position and strip edge location, enabling the control system to adjust cutting parameters and nozzle position dynamically. This feedback mechanism allows the distance sensor system to remain continuously operational without collision risk

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 enhances cutting effectiveness by allowing for shorter travel distances and improved precision, reducing processing time and enabling the cutting of sheet metal blanks with complex geometries.

Implementation Method 1

a first distance measuring device for cyclically measuring a distance between the cutting nozzle and a surface of the sheet metal strip

Methodology Applied
Scientific EffectCapacitive sensing: Capacitance

Data Source

PatentEP3849740B1Method and device for laser cutting a tailored blank from a continuously conveyed sheet strip
Publication Date: 2022.04.20 SCHULER PRESSEN GMBH & CO KG
  • EP3849740B1 patent drawingFigure 1~2
  • EP3849740B1 patent drawingFigure 3~4
  • EP3849740B1 patent drawingFigure 5~6

AI summary

The invention relates to a method for cutting a sheet metal blank from a sheet metal strip (1), which is being continuously conveyed in a transport direction (T), by means of at least one laser cutting device (3), having the following steps: providing a laser cutting device (3) with at least one laser cutting head (5) which has a cutting nozzle (7) and which can be moved along a cutting path (S1, S2, S1', S2') specified so as to correspond to the geometry of the sheet metal blank by means of a controller (6), incrementally measuring the distance between the cutting nozzle (7) and the surface of the sheet metal strip (1) at at least one radially outer position (P1, P2) relative to the cutting nozzle (7) by means of a first distance measuring device (8), controlling the movement of the laser cutting head such that the first distance measuring device (8, 9) constantly remains overlapping the sheet metal strip (1) when the cutting nozzle (7) is not overlapping the sheet metal strip, and moving the cutting nozzle (7) out of a first position, in which the cutting nozzle is not overlapping the sheet metal strip (1), into a second position, in which the cutting nozzle is overlapping the sheet metal strip (1), wherein the height of the cutting nozzle (7) relative to the surface of the sheet metal strip (1) is regulated using the first distance values supplied by the first distance measuring device (8, 9) when the cutting nozzle (7) is moved from the first position in the direction of the second position.