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CN-122007679-A - Laser processing system and method for processing a workpiece

CN122007679ACN 122007679 ACN122007679 ACN 122007679ACN-122007679-A

Abstract

A laser processing system for processing a workpiece by means of a laser beam, the laser processing system comprising a laser processing head having at least one focusing optics for focusing the laser beam such that the workpiece is heated and a process emission occurs, at least four optical sensors, wherein the optical sensors are insensitive to radiation having the wavelength of the laser beam and wherein the optical sensors are each arranged to detect the process emission in at least one wavelength range which does not contain the wavelength of the laser beam and to generate a corresponding sensor signal based thereon, and a control device, wherein the control device is arranged to monitor the processing of the workpiece based on an average value of the sensor signals.

Inventors

  • SCHUERMANN BERND
  • G. Speer

Assignees

  • 普雷茨特两合公司

Dates

Publication Date
20260512
Application Date
20251111
Priority Date
20241111

Claims (15)

  1. 1. A laser machining system (100) for machining a workpiece (W) by means of a laser beam (L), the laser machining system (100) comprising: -a laser processing head (10) having at least one focusing optics (13) for focusing the laser beam (L) such that the workpiece (W) is heated and a process emission (P) occurs; At least four optical sensors (17), wherein the optical sensors (17) are insensitive to radiation having the wavelength of the laser beam (L), and wherein the optical sensors (17) are each arranged to detect the process emission (P) in at least one wavelength range which does not contain the wavelength of the laser beam (L) and to generate a corresponding sensor signal based thereon, and -A control device (30), wherein the control device (30) is arranged to monitor the processing of the workpiece (W) based on an average value of the sensor signals.
  2. 2. The laser machining 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. 3. The laser processing system according to any of the preceding claims, wherein the optical sensor (17) comprises a semiconductor sensor, preferably wherein the semiconductor sensor is a compound semiconductor sensor, more preferably wherein the semiconductor sensor is a GaAsP sensor.
  4. 4. The laser machining system according to any 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. 5. The laser machining system of any of the preceding claims, wherein the optical sensor (17) is insensitive at least over a wavelength range of more than 900 nm, preferably more than 800 nm, and/or less than 550 nm, preferably less than 600 nm.
  6. 6. The laser processing system according to any 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 between 500 nm and 550 nm.
  7. 7. The laser processing system according to any one of the preceding claims, wherein the optical sensor (17) is arranged in the laser processing head (10), in particular wherein the laser processing head (10) comprises a housing (11) in which the optical sensor (17) is arranged.
  8. 8. The laser machining system according to any one of the preceding claims, wherein the optical sensor (17) is arranged before the focusing optics (13) with respect to the propagation direction of the laser beam (L).
  9. 9. The laser machining system according to any of the preceding claims, wherein the optical sensor (17) is arranged outside the optical path of the laser beam (L), and/or wherein the optical sensor (17) is arranged in a plane, which is perpendicular to the optical axis of the focusing optics (13), and/or wherein the optical sensor (17) is symmetrical with respect to the optical axis of the focusing optics (13).
  10. 10. The laser machining system according to any one of the preceding claims, further comprising an annular sensor arrangement (16), wherein the optical sensor (17) is arranged on an annular face (16 a) of the sensor arrangement (16), in particular wherein the sensor arrangement (16) is arranged coaxially with the optical axis of the focusing optics (13).
  11. 11. The laser processing system according to any of the preceding claims 1 to 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. 12. The laser machining system according to any one of the preceding claims, wherein the laser machining system (100) is arranged to penetrate 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. 13. The laser machining system according to any one of the preceding claims, wherein the control device (30) is arranged to determine a point in time at which the laser beam (L) penetrates the workpiece (W) based on the average value, to monitor a penetration process of the laser beam into the workpiece (W), to determine a quality of a machining of the workpiece (W), to determine a quality of a cut edge of the workpiece (W), and/or to adjust the machining process.
  14. 14. The laser machining system according to any one of the preceding claims, wherein the optical sensors (17) are connected in parallel, in particular wherein the average value of the sensor signal is one sensor signal obtained by connecting the optical sensors (17) in parallel.
  15. 15. Method for machining, in particular cutting, a workpiece (W) by means of a laser beam (L), wherein the method comprises the steps of: Irradiating the laser beam (L) onto the workpiece such that the workpiece (W) is heated and a process emission (P) occurs; Detecting the process emission (P) in at least one wavelength range which does not contain the wavelength of the laser beam (L) by means of at least four optical sensors (17), and generating a corresponding sensor signal based thereon, wherein the optical sensors (17) are insensitive to radiation having the wavelength of the laser beam (L), and The processing of the workpiece (W) is monitored on the basis of the average value of the sensor signals, in particular by means of a control device (30).

Description

Laser processing system and method for processing a workpiece Technical Field The present invention relates to a laser processing system and a method for processing a workpiece, in particular for piercing and/or cutting a workpiece. Background For machining a workpiece, in particular for cutting a workpiece, a laser beam is irradiated onto the surface of the workpiece. A region of the workpiece is heated by the laser beam so strongly that a part of the workpiece melts or evaporates. If the workpiece is to be cut, a laser beam is irradiated onto an area of the workpiece until the workpiece is penetrated, i.e., until a hole is formed in the workpiece, through which the laser beam can be irradiated. The laser beam then moves along a path on the workpiece, thereby creating a kerf. During processing, particularly by heating of the workpiece, the workpiece firing process fires. The process emission may include radiation in a wavelength range visible to humans. The laser machining process may be monitored based on the process emission. DE 196 44 101 C1 relates to a method for detecting beam penetration during machining of a workpiece using a laser beam, wherein the intensity of radiation from a machining point is detected by at least one sensor and a state signal is generated when a predefined intensity change occurs, wherein at least two averages of the detected radiation intensities are each formed for different time constants and the state signal is generated when the averages are in a predefined ratio to each other. Comparison of the measured values at two different points in time results in process monitoring being possible only with a time offset. Disclosure of Invention The object of the present invention is to provide a laser processing system and a method by means of which process monitoring can be carried out with a small time offset, in particular in real time or instantaneously. Another object of the invention is to provide a laser processing system and a method by means of which the accuracy of process monitoring can be increased. Another object of the invention is to provide a laser processing system and a method by means of which it is possible to monitor the laser processing process by means of a laser beam having a processing laser wavelength of less than 1200 nm with a simple design and/or with space-saving possibilities. At least the object is achieved by a laser processing system and a method according to the invention for processing a workpiece by means of a laser beam. The preferred embodiments are defined below in the description. A laser machining system for machining a workpiece by means of a laser beam is disclosed. The laser processing system includes a laser processing head having at least one focusing optic for focusing a laser beam onto a workpiece such that the workpiece is heated and process emission occurs. The laser machining system further includes at least four optical sensors. These optical sensors are insensitive to radiation having the wavelength of the laser beam. The optical sensors are 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 corresponding sensor signal based thereon. The laser processing system further comprises a control device. The control device is configured to monitor the processing of the workpiece based on an average of the sensor signals. A method for machining, in particular piercing and/or cutting, a workpiece by means of a laser beam is disclosed. The method comprises the steps of irradiating a laser beam onto a workpiece such that the workpiece is heated and a process emission occurs, detecting the process emission by means of at least four optical sensors in at least one wavelength range which does not contain the wavelength of the laser beam and generating corresponding sensor signals based thereon, wherein the optical sensors are insensitive to radiation having the wavelength of the laser beam, and monitoring the processing of the workpiece based on an average value of the sensor signals. The monitoring may be performed by means of a control device. The monitoring may include adjusting and/or controlling the process based on the average value. Each of the methods disclosed herein may be performed by each of the laser processing systems disclosed herein. In particular, the control device may be configured to average the sensor signals and/or to monitor the processing of the workpiece based on the average value. Each of the laser processing systems disclosed herein may be used in each of the methods disclosed herein. According to the invention, the sensor signals of these optical sensors are averaged. The average value may also be referred to as a common average value. The average value can be formed at a defined point in time, in particular instantaneously. By using a plurality of sensors that are insensitive to the laser wavelength and averaging the se