Laser cutting method and laser cutting machine for switching off beam at the end of cutting

Abstract

The invention relates to a method for cutting a cut profile (8) of a self-closing laser beam into a metal workpiece (2) by means of a laser beam (3) emitted by a laser cutting head (5). The distance (A) between the laser cutting head (5) and the workpiece (2) is determined by the laser beam cutting edge , The temporal gradient (dA / dt) of the distance measurement values (A) is determined for the detection of the end of the sectional contour (8) according to the invention at least on one end section (12) of the sectional contour (8), and a gradient threshold value (dA / Dt) S), and when the gradient threshold value ((dA / dt) S) is exceeded, the end of the sectional contour (8) is detected and the laser beam (3) is lowered in its power, in particular switched off.

Description

technical field [0001] The invention relates to a method for laser cutting a self-closing cutting contour into a metal workpiece by means of a laser beam emitted by a laser cutting head, wherein the laser cutting head (in particular the cutting nozzle of the laser cutting head) is measured The distance with respect to the workpiece, and the invention relates to an associated laser cutting machine and an associated computer program product. Background technique [0002] Such a laser cutting method and such a laser cutting machine are known, for example, from DE 11 2012 004 174 T5. [0003] It is known that in laser cutting for internal machining, a closed cutting contour is traversed by means of a laser beam in order to separate cut pieces (eg scrap pieces, product parts) from workpieces (sheets). For example, the laser can be stopped when the laser beam travels out of the entire cutting contour and reaches the point at which cutting begins on this cutting contour. That is ...

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Problems solved by technology

[0006] Furthermore, hanging of partially cut cutting blocks (e.g. in the case of bores with fragile / complex structures) can lead to false information from distance sensors (especially in the case of capacitive sensors for surface measurement) and thus Incorrect information on the distance of the cutting nozzle to the workpiece, so that instead of maintaining the ideal cutting distance, a distance with an offset is loaded, which is the "predetermined" for cutting off the laser beam with respect to the cutting nozzle relative to the workpiece Additional inaccuracies in terms of

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