Method and device for monitoring a laser processing process

Abstract

In a known method for monitoring a laser processing process, a laser beam is directed at a workpiece, scattered laser light is detected as scattered light, and a change in the state of the laser processing process is identified based on the detected scattered light intensity. The scattered light below the workpiece is detected and evaluated to identify the change in state.In order to provide a method for laser processing which uses scattered laser radiation to identify the current process state during laser processing and which ensures reliable process control, in particular for puncture detection, it is proposed according to the invention that the laser processing process comprises a process phase for detecting a workpiece edge, that the scattered light is detected below the workpiece support by means of at least one optically shielded detection device, that several stationary detection devices are used, and that the scattered light intensity is detected in a wavelength range which includes the wavelength λ of the laser radiation in the band range between λ + / - 100 nm.

Claims

[1] Method for monitoring a laser processing process, wherein a laser beam (3) is directed onto a workpiece (2), scattered laser light is detected as scattered light (10), and a change in state of the laser processing process is identified based on the detected scattered light intensity, wherein the laser beam (3) is generated by means of a laser cutting head (4; 5) which is moved by means of a machine gantry (31), and wherein scattered light (10) below the workpiece (2) is detected and evaluated to identify the change in state, characterized bythat the laser processing process comprises a process phase of detecting a workpiece edge, that the scattered light (10) is detected below the workpiece support (7) by means of at least one optically shielded detection device (9; 39), that several stationary detection devices (9) are used, and that the scattered light intensity is detected in a wavelength range which includes the wavelength λ of the laser radiation in the band range between λ + / - 100 nm. [2] Method according to claim 1, characterized by that the laser beam (3) is generated by means of a laser cutting head (4; 5) which is moved by means of a machine gantry (31), and that the at least one detection device (39) is moved synchronously with the movement of the machine gantry (31). [3] Method according to one of claims 1 or 2, characterized bythat the laser beam (3) is generated by means of a laser cutting head (4; 5) which is moved along a predetermined cutting contour and in the process creates a cutting groove in the cutting contour, and that the laser processing process comprises a process phase during which the movement speed and / or the energy input into the cutting groove is adjusted as a function of the detected scattered light intensity. [4] Device for monitoring a laser processing process with a laser cutting head (4; 5) for focusing a laser beam (3) on a workpiece (2), with an optical sensor (9; 39) for detecting scattered laser light as scattered light (10), and with an evaluation and control unit (6) by means of which the scattered light intensity is evaluated and, depending thereon, a change in the state of the laser processing process can be identified, wherein at least one optical device (9; 39) for detecting scattered light (10) is provided below the workpiece (2), which is connected to the evaluation and control unit (6), characterized bythat the device is designed to detect a workpiece edge, that at least one optically shielded detection device (9; 39) is provided for detecting scattered light (10) below the workpiece (2), that a plurality of stationary optical detection devices (9) are provided, and that the optical detection device (9) is designed to detect the scattered light intensity in a wavelength range which includes the wavelength λ of the laser radiation in the band range between λ + / - 100 nm. [5] Device according to claim 4, characterized by that a workpiece support (7) is provided which comprises a cutting grid. [6] Device according to one of claims 4 or 5, characterized by that the laser cutting head (4; 5) is movable by means of a machine portal (31), and that the at least one optical detection device (39) is movable synchronously with the movement of the machine portal (31).

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