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DE-102024132805-A1 - Laser processing system and method for processing a workpiece

DE102024132805A1DE 102024132805 A1DE102024132805 A1DE 102024132805A1DE-102024132805-A1

Abstract

A laser processing system for processing a workpiece using a laser beam comprises a laser processing head with at least one focusing optic for focusing the laser beam so that the workpiece is heated and process emission occurs; at least four optical sensors, wherein the optical sensors are insensitive to radiation with the wavelength of the laser beam and wherein the optical sensors are each configured to detect the process emission in at least one wavelength range that does not include the wavelength of the laser beam and to generate a respective sensor signal based thereon; and a control device, wherein the control device is configured to monitor the processing of the workpiece based on the average of the sensor signals.

Inventors

  • Bert Schürmann
  • Georg Spörl

Assignees

  • PRECITEC GMBH & CO. KG

Dates

Publication Date
20260513
Application Date
20241111

Claims (15)

  1. Laser processing system (100) for processing a workpiece (W) using a laser beam (L), the laser processing system (100) comprising: - a laser processing head (10) with at least one focusing optic (13) for focusing the laser beam (L) so that the workpiece (W) is heated and process emission (P) occurs; - at least four optical sensors (17), wherein the optical sensors (17) are insensitive to radiation with the wavelength of the laser beam (L) and wherein the optical sensors (17) are each configured to detect the process emission (P) in at least one wavelength range that does not include the wavelength of the laser beam (L) and to generate a respective sensor signal based thereon; and - a control device (30), wherein the control device (30) is configured to monitor the processing of the workpiece (W) based on an average of the sensor signals.
  2. Laser processing system according to Claim 1 , comprising at least six optical sensors (17), preferably at least ten optical sensors (17), preferably at least twenty optical sensors (17), preferably at least thirty optical sensors (17), preferably at least fifty optical sensors (17).
  3. Laser processing system according to one of the preceding claims, wherein the optical sensors (17) comprise semiconductor sensors, preferably wherein the semiconductor sensors are compound semiconductor sensors, more preferably wherein the semiconductor sensors are GaAsP sensors.
  4. Laser processing system according to one of the preceding claims, wherein all optical sensors (17) are of the same type or the optical sensors (17) comprise at least two different types of sensors.
  5. Laser processing system according to one of the preceding claims, wherein the optical sensors (17) are insensitive at least in a wavelength range of more than 900 nm, preferably more than 800 nm, and/or of less than 550 nm, preferably less than 600 nm.
  6. Laser processing system according to one of the preceding claims, wherein the laser beam (L) has a wavelength between 950 nm and 1200 nm, preferably between 1000 nm and 1150 nm, or has a wavelength between 500 nm and 550 nm.
  7. Laser processing system according to one of the preceding claims, wherein the optical sensors (17) are arranged in the laser processing head (10), in particular wherein the laser processing head (10) comprises a housing (11) and the optical sensors (17) are arranged in the housing.
  8. Laser processing system according to one of the preceding claims, wherein the optical sensors (17) are arranged in front of the focusing optics (13) with respect to the propagation direction of the laser beam (L).
  9. Laser processing system according to one of the preceding claims, wherein the optical sensors (17) are arranged outside the optical path of the laser beam (L) and/or wherein the optical sensors (17) are arranged in a plane perpendicular to the optical axis of the focusing optics (13) and/or symmetrically to the optical axis of the focusing optics (13).
  10. Laser processing system according to one of the preceding claims, further comprising a ring-shaped sensor arrangement (16), wherein the optical sensors (17) are arranged on the ring surface (16a) of the sensor arrangement (16), in particular wherein the sensor arrangement (16) is arranged coaxially to the optical axis of the focusing optics (13).
  11. Laser processing system according to one of the Claims 1 until 9 , wherein at least two optical sensors (17), preferably at least three or at least four optical sensors (17) are arranged in a stack (18), wherein the optical sensors (17) are arranged along a line, in particular wherein the laser processing system (100) comprises at least two stacks (18) with sensors (17).
  12. Laser processing system according to one of the preceding claims, wherein the laser processing system (100) is configured to pierce the workpiece (W) by means of the laser beam (L) and/or to cut the workpiece (W) by means of the laser beam (L).
  13. Laser processing system according to one of the preceding claims, wherein the control device (30) is configured to determine, based on the mean value, a penetration time of the laser beam (L) into the workpiece (W), to monitor a penetration process of the laser beam into the workpiece (W), to determine a quality of the processing of the workpiece (W), to determine a quality of a cut edge of the workpiece (W) and/or to control the processing process.
  14. Laser processing system according to one of the preceding claims, wherein the optical Sensors (17) are connected in parallel, in particular wherein the mean value of the sensor signals is a sensor signal obtained by the parallel connection of the optical sensors (17).
  15. A method for processing, in particular cutting, a workpiece (W) using a laser beam (L), the method comprising the steps of: - shining the laser beam (L) onto the workpiece, causing the workpiece (W) to heat up and process emission (P) to occur; - detecting the process emission (P) using at least four optical sensors (17) in at least one wavelength range that does not include the wavelength of the laser beam (L), and generating a corresponding sensor signal based thereon, wherein the optical sensors (17) are insensitive to radiation with the wavelength of the laser beam (L); and - monitoring the processing of the workpiece (W), in particular using a control device (30), based on an average of the sensor signals.

Description

The present disclosure relates to a laser processing system and a method for processing a workpiece, in particular for piercing a workpiece and/or cutting a workpiece. background To process a workpiece, particularly for cutting, a laser beam is directed onto its surface. The laser beam heats an area of the workpiece so intensely that a portion of it melts and/or vaporizes. To cut the workpiece, the laser beam is directed at that area until it penetrates the workpiece, i.e., until a hole forms through which the laser beam can pass. The laser beam is then moved along a path on the workpiece to create a cut. During processing, particularly due to the heating of the workpiece, the workpiece emits process emissions. These process emissions can include radiation in the visible wavelength range. The laser processing process can be monitored based on these process emissions. DE 196 44 101 C1 relates to a method for detecting beam transmission during the processing of a workpiece using a laser beam, in which the intensity of radiation coming from the processing point is detected by at least one sensor and a status signal is generated when there is a predetermined change in intensity, wherein at least two mean values of the intensity of the detected radiation are formed at different time constants, and the status signal is generated when the mean values are in a predetermined ratio to each other. Comparing two measured values at different times means that process monitoring can only take place with a time delay. Disclosure of the invention One objective of the present disclosure is to provide a laser processing system and a method by which process monitoring can be carried out with a small time lag, in particular in real time or instantaneously. Another objective of the present disclosure is to provide a laser processing system and a method by which the accuracy of process monitoring can be improved. A further objective of the present disclosure is to provide a laser processing system and a method by which a structurally simple and/or space-saving means of monitoring a laser processing process using a laser beam with a processing laser wavelength of less than 1200 nm is enabled. At least one of the problems is solved by the combination of features in the independent claims. Preferred embodiments are defined in the dependent claims and the description. Disclosed is a laser processing system for machining a workpiece using a laser beam (also referred to as a processing laser beam). The laser processing system comprises a laser processing head with at least one focusing optic for focusing the laser beam onto a workpiece, causing the workpiece to heat up and process emission to occur. The laser processing system further comprises at least four optical sensors. The optical sensors are insensitive to radiation with the wavelength of the laser beam. The optical sensors are configured to detect the process emission in at least (or exactly) one wavelength range that does not include the wavelength of the laser beam and to generate a corresponding sensor signal based on this detection. The laser processing system further comprises a control device. The control device is configured to monitor the machining of the workpiece based on an average of the sensor signals. A method for processing, in particular piercing and/or cutting, a workpiece using a laser beam is disclosed. The method comprises the steps of: shining the laser beam onto the workpiece so that the workpiece heats up and process emission occurs; detecting the process emission using at least four optical sensors in at least (or exactly) one wavelength range that does not include the wavelength of the laser beam, and generating a corresponding sensor signal based on this detection, wherein the optical sensors are insensitive to radiation with the wavelength of the laser beam; and monitoring the processing of the workpiece based on an average of the sensor signals. The monitoring can be carried out using a control device. The monitoring can include regulating and/or controlling the processing process based on the average. Each method disclosed herein can be carried out by each laser processing system disclosed herein. In particular, the control device can be configured to determine the average value of the to generate alarm signals and/or to monitor the machining of the workpiece based on the mean value. Each laser processing system disclosed herein can be used in each of the processes disclosed herein. According to the present invention, an average value is calculated from the sensor signals of the optical sensors. This average value can therefore also be referred to as the common average. The average value can be calculated at a specific point in time, in particular instantaneously. By using a plurality of sensors that are insensitive to the laser wavelength and by averaging the sensor signals, the processing process can be monitored virtually without delay. This is p