DE102022127449A1 - Laser processing head with lidar sensor - Google Patents

Abstract

The present disclosure relates to a laser processing head for processing a workpiece by means of a laser beam, comprising: a housing in which a focusing optics for focusing the laser beam is arranged; and at least one lidar sensor for detecting a distance between the laser processing head and an object in a process space; wherein the lidar sensor is attached to the outside of the housing and a beam path of the lidar sensor runs outside the housing.

Description

The present disclosure relates to a laser processing head for processing a workpiece by means of a laser beam with at least one lidar sensor for detecting objects in the environment.

Technical background

When machining a workpiece using a laser beam, i.e. during laser processing, the laser beam is usually guided along a processing path by a relative movement between a laser processing head irradiating the laser beam and the workpiece.

Higher laser powers in laser cutting and welding enable ever higher process speeds, which significantly increases the requirements for controlling or regulating the processing process and increases the potential danger due to the high laser power. In particular, the requirements for collision prevention are increasing, as the reaction time is reduced and possible collisions can have more drastic consequences. It is therefore advantageous to optically measure the area around the laser processing head so that unforeseen objects can be detected. Sensors are therefore required that scan the space around the laser processing head in a non-contact and three-dimensional manner in order to detect any interfering parts, such as protruding components, different sheet thicknesses or dirt.

DE 28 29 851 A1 describes an arrangement for measuring the distance between a metallic workpiece and a machining tool by means of a capacitive distance sensor, which enables the machining of workpieces with irregular surfaces and in particular elevations running parallel to the tool path.

EN 10 2017 201 730 A1 relates to a method for welding and a welding arrangement, wherein a time-of-flight (ToF) detection device is used to detect an observation window on the workpiece which at least partially precedes the welding point.

EN 10 2015 015 651 B3 relates to a monitoring device for a laser processing system with a measuring beam source and a registration unit that detects a portion of the measuring beam reflected by the environment. The measuring beam is coupled coaxially to the processing beam into a laser processing head so that the measuring beam and processing beam can be aligned to common positions in the environment.

EN 10 2012 212 278 A1 relates to an arrangement for producing holes or weld seams, wherein a distance between the workpiece and the arrangement is detected by means of a coaxial autofocusing unit. The autofocusing unit can comprise an OCT device, a ToF camera or a triangulation unit.

Summary of the invention

It is an object of the present invention to provide a laser processing head with an efficient and versatile device for process space observation, in particular for observing the three-dimensional process space.

It is a further object of the present invention to provide a laser processing head with a device for process space observation, which enables reliable object detection in the process space even at high process or machining speeds.

It is a further object of the present invention to provide a laser processing head with a device for process space observation, which enables a planar object recognition or a planar detection of obstacles in the process space.

It is a further object of the present invention to provide a laser processing head with a device for process space observation, which enables control or regulation of the processing process, in particular for monitoring the processing process and/or for collision prevention, through reliable object detection in the process space.

At least one of these objects is solved by the subject matter of independent claim 1.

According to one aspect of the present disclosure, a laser processing head for processing a workpiece by means of a laser beam comprises: a housing in which an optic for guiding and/or shaping the laser beam, for example a focusing optic for focusing the laser beam, is arranged; at least one lidar sensor for detecting a distance between the laser processing head and an object in a detection space or in a process space; wherein the lidar sensor is attached to the outside of the housing and a beam path of the lidar sensor runs outside the housing.

According to a further aspect, a method for monitoring a laser processing process comprises the steps of: performing the laser processing process by irradiating a laser beam from a laser processing head (e.g. a laser processing head according to one of the embodiments described herein) onto at least one workpiece, wherein the laser processing head and the workpiece are moved relative to one another along a processing path, detecting distance data during the laser processing process by at least one lidar sensor arranged on the laser processing head, which scans a first detection space and a second detection space and detects corresponding distance data, wherein the first detection space is at a greater distance from the laser processing head than the second detection space and the lidar sensor detects the distance data of the first detection space with a lower resolution (or with a coarser pixel grid and/or with a lower sampling rate) than the distance data of the second detection space, and determining based on the detected distance data whether there is an obstacle in an area along the processing path in the first detection space and/or in the second detection space. The first detection area can also be referred to as the long-range area and the second detection area as the short-range area. The lidar sensor can be attached to the outside of the laser processing head or to a housing of the laser processing head and/or a beam path of the lidar sensor can run outside the laser processing head or a housing of the laser processing head.

The laser processing head may comprise a controller configured to carry out the method according to one of the embodiments of the present invention.

In the present disclosure, a process space is referred to as a space within which the laser processing head can move relative to the workpiece, and in particular a space within which the laser processing head can move relative to the workpiece during the processing process and/or along a processing path specified for the processing process. In other words, the process space is defined with respect to the workpiece, i.e. the workpiece is stationary in the process space. The detection space is the area of the process space that can be detected by the lidar sensor or in which the lidar sensor can detect objects. The detection space is an area of the process space, i.e. the detection space is located in the process space. The detection space can be defined by a mounting height of the lidar sensor on the laser processing head and/or a detection or opening angle of the lidar sensor. The TCP area is the area of the process space into which the laser beam can be directed with respect to the laser processing head. In the case of a fixed optics laser processing head, this can only be the beam path of the laser beam exiting the laser processing head, i.e. a line that includes the TCP (tool center point, also called processing point) or the focus point of the laser beam. In the case of a scanner laser processing head, this can be a cone-like space that is determined by the beam deflection properties of the scanning device.

The present disclosure deals with three-dimensional (3D) imaging for laser cutting and welding using at least one lidar sensor (light-detection and ranging, also known as Ladar, laser-detection and ranging). The lidar sensor can in particular be a lidar camera. In particular, the two subgroups of AMCW lidar sensors (amplitude-modulated continuous wave, also known as indirect time-of-flight, iToF) and FMCW lidar sensors (frequency-modulated continuous wave) can be used. According to the invention, the space outside the immediate processing area or the TCP area is to be measured, for example in order to detect objects arranged in the vicinity of the laser processing head. Objects can be obstacles that are on or in an area around a predetermined processing path for laser processing, i.e. objects that would collide with the laser processing head due to the relative movement between the laser processing head and the workpiece along the processing path. Such obstacles can be protruding sheet metal parts, workpieces or sheets of different thicknesses, dirt, a clamping device for holding the workpiece, etc. Objects can also be features of the machined or unmachined workpiece(s), such as a joining edge or a joint between two workpieces (i.e. in the lead-in); a marking or positioning aid on a clamping or holding device for holding the workpiece or a marking or positioning aid on the workpiece or lateral contours of the workpiece for orientation or alignment of the laser processing head; a topography or surface curvature or inclination of the workpiece; or a weld seam or cutting edge created by the laser processing (i.e. in the lead-in).

The laser processing head according to the invention offers very extensive possibilities for process space observation due to the enormous versatility of the lidar sensor with a single implementation. In particular, this enables object detection in areas that can be used for process control and/or for collision prevention control.

• Der Laserbearbeitungskopf kann ein Laserbearbeitungskopf zum Durchführen eines Bearbeitungsprozesses, insbesondere zum Laserschneiden, Laserschweißen, Laserlöten, Laserbohren etc., an dem Werkstück mittels des Laserstrahls sein.

The laser processing head or the method according to one of the aspects listed above may comprise one or more of the following features:

• The laser processing head can be a laser processing head for performing a processing process, in particular for laser cutting, laser welding, laser soldering, laser drilling, etc., on the workpiece by means of the laser beam.

The lidar sensor can be attached to the outside of the housing (i.e. outside the optical space defined in the housing), preferably removable or reversible. The lidar sensor can be a lidar camera and/or set up for spatially resolved distance detection. In other words, the lidar sensor can be set up to detect objects in a three-dimensional detection space. The lidar sensor can be a ToF-based sensor. The lidar sensor can be an FMCW lidar sensor or an AMCW lidar sensor, i.e. the radiation can be periodically amplitude or frequency modulated. These two techniques are suitable for spatial resolution in the sub-millimeter range.

The lidar sensor may comprise at least one detector and at least one emitter. The detector and the emitter may be spatially adjacent to each other or spatially separated from each other. If the detector and the emitter are spatially separated from each other, the emitter could illuminate detection spaces of different detectors. In other words, several detectors could share one emitter.

The lidar sensor or the detector can comprise at least one photodiode, a diode array, a CMOS sensor, at least one avalanche photodiode, etc. The lidar sensor or the emitter can comprise a beam source, in particular a laser beam source, a beam source array, a laser beam source array, at least one LED, an LED array, at least one VCSEL, a VCSEL array, etc. The emitter or the beam source can be a laser beam source or a beam source array in the visible, near-infrared or infrared frequency range.

The lidar sensor may further comprise beam-forming optics, such as a diffuser, a diffractive element, a wide-angle lens, or modulation optics.

The lidar sensor may further comprise a protective glass and/or a crossjet device for generating an air curtain to protect against contamination, e.g. by smoke or splashes.

The detection area of the lidar sensor can be at least partially outside the TCP area and/or include an area of the workpiece surface. In particular, the TCP can be outside the detection area of the lidar sensor. The detection area of the lidar sensor can also be completely outside the TCP area, i.e. not include the TCP area. The detection area of the lidar sensor can be at least partially or only partially limited by the workpiece surface. The detection area of the lidar sensor can be limited by the detection angle of the lidar sensor and at least partially by the workpiece or the workpiece surface. The detection area of the lidar sensor can be arranged (at least partially) in the lead and/or trail of the laser processing head, and/or to the side of the laser processing head. In the lead of the laser processing head there is an area of the workpiece to be processed, in the trail there is an area of the workpiece that has already been processed.

The lidar sensor can be arranged on the housing in such a way that an optical axis of the lidar sensor and/or a central axis of its detection space forms an angle greater than 0° and/or less than 90° to the optical axis of the focusing optics or to a vertical axis, in particular an angle greater than 20°, 30° or 45°.

The lidar sensor can be pivotably and/or displaceably attached to the housing so that a position of the detection space and/or the optical axis of the lidar sensor can be adjusted. The lidar sensor, in particular the emitter and/or the detector of the lidar sensor, can be pivotable about an axis that runs perpendicular to the optical axis of the focusing optics and/or horizontally and/or parallel to one side of the housing. In other words, a radiation and/or detection angle of the lidar sensor can be adjustable. The lidar sensor, in particular the emitter and/or the detector of the lidar sensor, can be displaceable parallel to the optical axis of the focusing optics and/or in the vertical direction on the housing. In other words, a mounting height of the lidar sensor can be adjustable. The mounting height and the radiation or detection angle are crucial for the size of the detection space and in particular for the size of a measuring range.

The housing may include a guide, e.g. a rail, along which the lidar sensor is slidable. An edge of the housing, e.g. a bottom edge, and/or a corner of the housing, e.g. a bottom corner, may have a bevel or a tapered surface to which the lidar sensor is attached.

The lidar sensor can comprise a holder. The lidar sensor, i.e. the emitter and/or the detector of the lidar sensor, can be accommodated in the holder. The holder can be pivotably and/or displaceably and/or detachably and/or rotatably attached to the housing. Alternatively or additionally, the emitter and/or the detector can be pivotably and/or displaceably arranged in the holder. The lidar sensor can be pivotable by motor and/or automated means about an axis perpendicular to the optical axis of the focusing optics and/or about a horizontal axis.

A controller, e.g. the lidar controller or the controller of the laser processing head, can be configured to control the lidar sensor so that it is pivoted back and forth between two positions. In this way, the lidar sensor can, for example, have a first detection space in the far range and a second detection space in the near range. The controller can also be configured to adapt a (lateral and/or axial) resolution of the lidar sensor to the respective detection space. For example, the controller can be configured such that a (lateral and/or axial) resolution of the lidar sensor is lower in the first detection space than in the second detection space.

The lidar sensor can be configured to capture its detection space with different (lateral and/or axial) resolutions. In other words, a (lateral and/or axial) resolution of the lidar sensor can be adjustable. A controller, e.g. the lidar controller or the controller of the laser processing head, can be configured to set a (lateral and/or axial) resolution of the lidar sensor.

The laser processing head can comprise a module that contains the at least one lidar sensor and that is detachably attached to the housing. The module can be attached coaxially to the housing. The module can have an opening for the beam path of the laser beam, i.e. to allow the laser beam to pass through centrally. The module can be attached between the housing and a nozzle or on an underside of the housing. The module can comprise several, in particular at least four, lidar sensors that are arranged around the optical axis of the focusing optics. The module can be attached to the housing in a motorized or manually rotatable manner. Such a rotatable sensor system can reduce a blind spot or a blind area around the laser processing head, i.e. an area that cannot be detected by any lidar sensor. All-round visibility is therefore possible. The module can comprise an interface to transmit data from the lidar sensor to a controller of the laser processing head (wirelessly or wired). The module can comprise an electronic component and/or a module controller and/or a lidar controller for controlling the at least one lidar sensor and possibly other components of the module. The module can comprise a gas connection for a crossjet device. The module can comprise a lower edge with a bevel or a beveled lower edge and/or a beveled corner on which at least one of the lidar sensors is arranged.

The laser processing head can comprise a lidar controller for controlling the at least one lidar sensor and/or for evaluating data from the at least one lidar sensor. The lidar controller can be configured to generate a distance signal from the data acquired by the at least one lidar sensor. The lidar controller can be connected to a controller of the laser processing head (wired or wireless) for unidirectional or bidirectional exchange of data, or can be integrated into it.

The laser processing head can comprise several lidar sensors. If the detection spaces of the lidar sensors overlap, the lidar sensors with overlapping detection spaces can be sensitive to different wavelengths (ranges). For example, filters for different wavelengths (ranges) can be arranged in front of the detectors of the lidar sensors with overlapping detection spaces, and/or the emitters of the lidar sensors with overlapping detection spaces can emit in different wavelengths (ranges). The lidar sensors with overlapping detection spaces can also be controlled alternately, e.g. by a common lidar control of the lidar sensors, which can also be the control of the laser processing head or be integrated into it. In other words, these lidar sensors can be controlled so that their detection periods and/or their emission or illumination periods do not overlap.

The at least one lidar sensor can comprise a first lidar sensor with a first detection area and a second lidar sensor with a second detection area. The second detection area (near area) can be closer to the laser processing head than the first detection area (far area). The optical axis of the first lidar sensor can form a larger angle to the optical axis of the focusing optics than the optical axis of the second lidar sensor. The optical axis of the first lidar sensor can form an angle to the optical axis of the focusing optics between 70° and 110°, in particular of approximately 90°. The optical axis of the second Lidar sensors can form an angle to the optical axis of the focusing optics between 10° and 50°, in particular between 30° and 40°. The first detection area can be smaller than the second detection area.

The first sensor can be set up to detect distances in its detection area with a lower (lateral and/or axial) resolution than the second sensor. Alternatively, a controller can be set up to control the first and second sensors so that the first sensor detects distances with a lower (lateral and/or axial) resolution than the second sensor. In other words, an area close to the laser processing head can be measured with a higher (axial and/or lateral) resolution than a distant area. For example, no obstacle can be overlooked in a close area, while in the distance the reaction time is longer and therefore less precision is required.

It can therefore be advantageous to measure obstacles using different measuring grids. Obstacles that are closer to the laser processing head should be scanned with a higher resolution than obstacles that are further away. At the same time, however, the scanning area for closer obstacles does not need to be as large as for obstacles that are further away.

The laser processing head can comprise a third lidar sensor with a third detection space, wherein the third lidar sensor is arranged on a front side of the laser processing head, i.e. in the direction of movement of the laser processing head in the process space, and/or a fourth lidar sensor with a fourth detection space, wherein the fourth lidar sensor is arranged on a rear side of the laser processing head. The third detection space can therefore be located in the front of the laser processing head and/or the fourth detection space can be located in the back of the laser processing head. The fourth lidar sensor can be configured to detect objects with lower (lateral and/or axial) resolution than at least one of the first, second and third lidar sensors.

For 3D imaging, different measurement grids can be used with regard to the lateral and axial resolution as well as the extent of the space to be imaged. For example, the deep space or the far area (>50cm and <500cm in relation to the TCP) or a detection area in the follow-up can be scanned with a coarser, wider grid than the near space or the near area (>20cm and <50cm in relation to the TCP) or a detection area in the lead-up.

The laser processing head can comprise a controller for controlling and/or regulating the processing process, e.g. based on the distance data recorded by the at least one lidar sensor. The controller can comprise a lidar controller for controlling the at least one lidar sensor and/or for evaluating data or distances recorded by the lidar sensor. The controller can be set up to prevent collisions by classifying an object as critical or non-critical based on the data or distances recorded by the lidar sensor. An object can be classified as critical or non-critical depending on process parameters, e.g. a feed rate or speed of the laser processing head in the process space, a (mechanical and/or sensory) system inertia, a reaction time, a predetermined processing path, etc. Non-critical here means that the laser processing head would not collide with the object when moving along a predetermined processing path - be it due to the position or the size of the object. Accordingly, critical means that the laser processing head would collide with the object.

The controller can be configured to carry out a collision prevention measure. The measure can be selected according to a distance of the object classified as critical from the laser processing head from at least one of: bypassing the object, stopping the processing process, switching off the laser beam, and slowing down or stopping a relative movement between the laser processing head and the workpiece.

The resolution requirements can be related to a reaction space of the laser processing head. This reaction space is defined by a reaction time, i.e. the time required for the laser processing head or the laser processing system to react to an obstacle. The reaction or measure can vary and range from bypassing to decelerating to an emergency stop of the machine. A reaction also includes the possible switching off or blocking of the laser beam.

The unit can also be used to measure the distance of the cutting nozzle to the top of the sheet or to contours on the side. In this way, a capacitive distance sensor could be calibrated in absolute units or even replaced.

Short description of the characters

• 1 eine schematische Darstellung eines Laserbearbeitungskopfs mit einem Lidarsensor und einem zweiten Lidarsensor, die jeweils außerhalb des Laserbearbeitungskopfs angeordnet sind;
• 2 eine weitere schematische Darstellung des Laserbearbeitungskopfs mit dem Lidarsensor, dem zweiten Lidarsensor und einem dritten Lidarsensor, die jeweils außerhalb des Laserbearbeitungskopfs angeordnet sind;
• 3A bis 3D verschiedene Anordnungen des Lidar-Sensors am Laserbearbeitungskopf.
• 4A bis 4C verschiedene Anordnungen mehrerer Lidar-Sensoren am Laserbearb eitungskopf.
• 5A und 5B ein an dem Laserbearbeitungskopf befestigbares Modul, in dem zumindest ein Lidar-Sensor angeordnet ist.

Embodiments of the disclosure are shown in the figures and are described in more detail below. They show:

• 1 a schematic representation of a laser processing head with a lidar sensor and a second lidar sensor, each arranged outside the laser processing head;
• 2 a further schematic representation of the laser processing head with the lidar sensor, the second lidar sensor and a third lidar sensor, each arranged outside the laser processing head;
• 3A to 3D different arrangements of the lidar sensor on the laser processing head.
• 4A to 4C different arrangements of several lidar sensors on the laser processing head.
• 5A and 5B a module which can be attached to the laser processing head and in which at least one lidar sensor is arranged.

Detailed description of the figures

In the following, unless otherwise stated, the same reference symbols are used for identical and equivalent elements.

1 shows a laser processing head 1 with a housing 2, a focusing optics 9 and a nozzle 8. The focusing optics 9 comprise a lens or a lens group for focusing the laser beam 3. The laser beam then exits through an opening from the nozzle 8 and strikes a processing area or TCP 5 on the workpiece. The processing area 5 can be a cutting groove 6 in a workpiece 4 or a weld seam 6 between two workpieces 4. Furthermore, a controller can be integrated into the laser processing head 1 or connected to the laser processing head 1 in a wired or wireless manner. The controller 100 serves to control the laser processing head 1 and its components or to control the implementation of a laser processing process. The controller 100 can also control the lidar sensor 11 and/or evaluate the data acquired by the lidar sensor.

A (first) lidar sensor 11 is arranged on an outside of the housing 2, e.g. on the front in the processing direction. The lidar sensor 11 can detect objects in a first detection space 111 or determine distances to objects in this detection space 111. The lidar sensor 11 can generate a first scanning grid 112 with a predetermined first resolution. The lidar sensor 11 is set up to detect objects in the advance, i.e. objects arranged in front of the laser processing head with respect to the processing direction. The detection space 111 of the first lidar sensor 11 is preferably directed into the space, but can be partially limited by the workpiece 4.

A second lidar sensor 12 can be arranged on a lower edge of the housing 2. The second lidar sensor 12 can detect objects in a second detection area 121 or determine distances to objects in this detection area 121 that is located closer to the laser processing head (near range). The lidar sensor 12 can generate a second sampling grid 122 with a predetermined second resolution. The second resolution can be higher than the first resolution or the second sampling grid 122 can be finer than the first sampling grid 112. The resolution of the lidar sensor 11 or 12 can also be set accordingly by the controller 100.

A central axis of the first detection space 111 (i.e. the central axis that leads through the first lidar sensor) forms a larger angle with the optical axis of the focusing optics 9 than a central axis of the second detection space 121. In other words, the second lidar sensor 12 is directed more towards the workpiece or downwards than the first lidar sensor 11. The second detection space 121 may be smaller than the first detection space 111. The second detection space 121 and the first detection space 111 may be separated from each other (as in 1 shown), or overlap (as in 2 shown).

The first lidar sensor 11 and the second lidar sensor 12 can be arranged on the same side of the housing 2, for example as shown here on a front side or directed towards the front. However, the sensors can also be arranged on different sides of the housing 2. Additional lidar sensors can also be arranged on the outside or outsides of the housing 2. In the 1 and 2 In the examples shown, both detection spaces 111 and 121 are directed in the lead, ie directed forward in the processing direction. However, the present disclosure is not limited to this. The two detection spaces 111 and 121 can also be directed in different directions, eg in the lead and in the follow-up.

2 shows a further embodiment of the laser processing head 1 with a third lidar sensor 13, which is arranged on an outside of the housing 2, between the second lidar sensor 12 and the first lidar sensor 11. The third Lidar sensor 13 has a third detection space 131 and generates a third sampling grid 132. The first sampling grid 111, the second sampling grid 122, and the third sampling grid 132 may overlap and have a different size or have different grids with different sizes.

3A to 3D show different arrangements of a lidar sensor on the laser processing head 1. One or more lidar sensors can be arranged according to one or more of the 3A to 3D shown different arrangements can be provided on the laser processing head 1. The first, second and/or third lidar sensor of the 1 or 2 may be subject to one or more of the 3A to 3D shown different arrangements on the laser processing head 1. For the sake of clarity, the lidar sensor is shown in the 3A to 3D designated 11, but this should not be understood as limiting.

As already mentioned above, the lidar sensor 11 has a detection space 111. The detection space 121 is defined by the opening or detection angle 113 of the lidar sensor 11 and the position of the lidar sensor on the laser processing head 1 or on the housing 2. A bisector of the detection angle 113 forms a central axis 114 of the detection space 111. The central axis 114 of the detection space 111 can correspond to the optical axis of the lidar sensor 11.

3A shows a housing 2 of the laser processing head 1, which has a bevel, i.e. a bevelled edge, on a lower edge. The bevel can be formed on a lower edge of the housing 2 and/or on a lower corner of the housing 2. The lidar sensor 11 is arranged on or at the bevel. In this way, the lidar sensor 11 is aligned obliquely downwards, i.e. directed obliquely towards the workpiece. The detection space 111 can be at least partially delimited by the workpiece surface (and the detection angle 113). The housing 2 can have a rectangular cross-section and have a bevel on at least two lower edges, on each of which at least one lidar sensor is arranged. The housing 2 can have a rounded cross-section and a peripheral lower edge can be formed all around as a bevel, on which at least one lidar sensor is arranged.

3B shows a housing 2 of the laser processing head 1, on the outside of which a holder 1111 with the lidar sensor 11 is rotatably or pivotably attached. The holder 1111 with the lidar sensor 11 can be rotated about a rotation axis 1113, which runs horizontally and/or parallel to the outside, with respect to the housing 2. The holder 111 with the lidar sensor 11 can be rotated automatically or by motor or manually. Thus, an orientation of the lidar sensor 11 or the detection space 111 of the lidar sensor 11 can be adjusted. In particular, an angle between the optical axis of the focusing optics 9 or the workpiece surface and the central axis 114 of the detection space 111 can be adjusted. The holder 1111 can additionally have a bevel on a lower outer edge, on which the lidar sensor 11 can be attached. The holder 1111 can be attached to the housing 2 via a housing holder 1112. The bracket 1111 can be rotatably attached to the housing bracket 1112.

3C shows a housing 2 of the laser processing head 1, on the outside of which a rail 1114 is attached or integrated. A holder 1111 with the lidar sensor 11 is attached to the rail 1114. The holder 1111 can be moved on the rail 1114 along a vertical and/or horizontal displacement direction 1115. The holder 111 with the lidar sensor 11 can be moved automatically or by motor or manually. Thus, a mounting height or position of the lidar sensor 11 or the detection space 111 of the lidar sensor 11 can be adjusted. The holder 1111 can additionally have a bevel on a lower outer edge on which the lidar sensor 11 can be attached.

3D shows an arrangement of the lidar sensor on the housing 2 of the laser processing head 1, in which the arrangements of 3B and 3C are combined. The holder 1111 with the lidar sensor 11 is displaceable along the rail 1114 on the outside of the housing and is additionally arranged to be rotatable about the axis of rotation 1113 with respect to the housing 2 or the laser processing head.

4A to 4C show arrangements of four lidar sensors 11 on the laser processing head 1 and their detection areas 111. However, fewer or more than four sensors can also be provided on the laser processing head. The arrangement on the laser processing head can be as in the 3A to 3C shown. In the 4A to 4C The laser processing head 1 is shown from below.

In 4A Four lidar sensors 11 are arranged on each outer side of the housing 2. In 4B Four lidar sensors 11 are mounted on a bevelled lower edge of the housing. The center axes of the detection areas of neighboring lidar sensors are at a 90° angle to each other. With such an arrangement, objects or obstacles in the process area can be detected in all directions. The detection spaces 111 of the lidar sensors 11 may overlap, but this is not necessary.

In 4C the laser processing head 1 has, in addition to the 4A or 4B In addition to the four lidar sensors 11 arranged at each corner of the housing 2 of the laser processing head 1, there is an additional lidar sensor 11. The center axes of the detection areas of neighboring lidar sensors are each at a 45° angle to each other. This enables an all-round view.

The lidar sensors 11, which are installed in the 4A to 4C can also be arranged in a module 20. The module can be reversibly attached to the housing 2, for example arranged between the housing 2 or the focusing optics 9 and the nozzle 8.

5A and 5B show embodiments of the module 20, which can be attached between the housing 2 and the nozzle 8 and contains at least one lidar sensor 11. Preferably, at least one lidar sensor 11 is arranged on each side of the module 20, for example as in 4A to 4C shown.

5A shows an embodiment of the module 20 in which a lidar sensor 11 is arranged on a bevelled corner. The lidar sensor 11 is protected from contamination by a protective glass 10. At least one crossjet device with at least one ventilation opening 22 can also be arranged adjacent to the lidar sensor 11 in order to protect the lidar sensor or the protective glass from smoke and other contamination by means of an air curtain. The crossjet device is designed to blow a gas, e.g. compressed air, which is supplied through a connection 23 of the module, through the ventilation opening 22 like a curtain over the lidar sensor 11.

5B shows an embodiment of the module 20 in which two lidar sensors 11 are arranged on one side of the module 20. Of course, only one lidar sensor 11 can be arranged on one side. The module can have a bevelled lower edge on which the lidar sensors 11 are arranged. The lidar sensors 11 can be arranged as in 4A to 4C shown. The lidar sensors 11 can be protected from contamination by a protective glass 10 and/or a crossjet device.

The laser processing head comprises a controller 100 for controlling and/or regulating the processing process, e.g. based on the distance data recorded by the at least one lidar sensor 11, 12, 13. The controller can comprise a lidar controller for controlling the at least one lidar sensor and/or for evaluating data or distances recorded by the lidar sensor, or can communicate with such a controller in a wired or wireless manner. The controller 100 can be set up to carry out a collision prevention measure. The controller 100 can be set up for collision prevention to classify an object as critical or non-critical based on the data or distances recorded by the lidar sensor. An object can be classified as critical or non-critical depending on process parameters, e.g. a feed rate or speed of the laser processing head in the process space, a (mechanical and/or sensory) system inertia, a reaction time, a specified processing path, etc. Non-critical here means that the laser processing head would not collide with the object when moving along a specified processing path - be it due to the position or the size of the object. Accordingly, critical means that the laser processing head would collide with the object. A critical object can be described as an obstacle.

The controller 100 can be configured to carry out a method for monitoring a laser processing process with the following steps: carrying out the laser processing process by irradiating a laser beam 3 onto the workpiece 4 using the laser processing head 1, wherein the laser processing head and the workpiece are moved relative to one another along a processing path, detecting distance data during the laser processing process using at least one lidar sensor 11, 12, 13 arranged on the laser processing head 1, and determining based on the detected distance data whether an obstacle or a critical object is present in an area along the processing path. The controller 100 of the laser processing head 1 can be configured to carry out the method.

In the step of acquiring distance data, the lidar sensor can scan a first detection space and a second detection space and acquire corresponding distance data, wherein the first detection space has a greater distance from the laser processing head than the second detection space. The first detection space can also be referred to as the long range and the second detection space as the short range. The lidar sensor can be movably attached, e.g. rotatably, to the laser processing head in order to scan the two different detection spaces. A resolution of the lidar sensor can be adjustable so that the lidar sensor scans the first detection space (long range) with a lower resolution than the second detection space (short range). Two lidar sensors can also be provided, one of which scans the first detection area and the other the second detection area. The first lidar sensor for scanning the first detection area can have a lower resolution than the second lidar sensor for scanning the second detection area. The detection area of the lidar sensor or the detection areas of the lidar sensors are preferably directed in the forward direction.

When two different detection spaces are scanned, the method may further comprise: determining, based on the detected distance data, whether there is an obstacle in an area along the processing path in the first detection space and/or whether there is an obstacle in an area along the processing path in the second detection space.

The method may further comprise: selecting a collision prevention measure according to a distance of the obstacle from the laser processing head or based on whether the obstacle is in the first or second detection space. Examples of collision prevention measures include: driving around the object, stopping the processing process, turning off the laser beam, and slowing down or stopping a relative movement between the laser processing head and the workpiece.

The use of at least one lidar sensor, whose beam path runs outside the laser processing head and/or whose optical axis or central axis of the detection space is aligned at an angle to the optical axis of the focusing optics (and/or to the vertical direction), on a laser processing head enables cost-effective, flexible and versatile process monitoring for a processing process.

List of reference symbols

1

Laser processing head

2

Housing

3

laser beam

4

workpiece

5

Processing area (TCP)

6

Cutting joint and/or weld seam

7

chamfer

8th

jet

9

Focusing optics

11

(first) lidar sensor

111

Recording area

112

Sampling grid

113

Detection angle

114

Central axis of the detection area

1111

bracket

1112

Housing bracket

1113

Rotation axis

1114

rail

1115

Displacement direction

12

second lidar sensor

121

second recording room

122

second sampling grid

13

third lidar sensor

131

Detection area of the third lidar sensor

132

Sampling pattern of the third lidar sensor

20

module

21

Protective glass

22

Crossjets or ventilation openings

23

Gas connection

24

Sensor side

100

steering

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• DE 2829851 A1 [0004]
• DE 102017201730 A1 [0005]
• DE 102015015651 B3 [0006]
• DE 102012212278 A1 [0007]

Claims (14)

Laser processing head (1) for processing a workpiece (4) using a laser beam, comprising: a housing (2) in which a focusing optics (9) for focusing the laser beam (3) is arranged; at least one lidar sensor (11, 12, 13) for detecting a distance between the laser processing head (1) and an object in a process space; and wherein the lidar sensor (11, 12, 13) is arranged on the outside of the housing (2) and a beam path of the lidar sensor (11, 12, 13) runs outside the housing (2). Laser processing head (1) according to Claim 1 , wherein the lidar sensor (11, 12, 13) is arranged on the housing (2) such that a detection space (111, 121, 131) of the lidar sensor (11, 12, 13) lies at least partially outside the TCP area and/or comprises an area of the workpiece surface. Laser processing head (1) according to one of the preceding claims, wherein the optical axis of the lidar sensor (11) and/or the central axis of the detection space (114) forms an angle greater than 0° and/or less than 90° to the optical axis of the focusing optics. Laser processing head (1) according to one of the preceding claims, wherein the lidar sensor (11) is pivotably and/or displaceably mounted on the housing (2) so that a position of the detection space (111) and/or the central axis of the detection space (114) and/or the optical axis of the lidar sensor (1) is adjustable. Laser processing head (1) according to one of the preceding claims, wherein the housing (2) has a rail (1114) along which the lidar sensor (11) is displaceable, and/or has a lower edge with a bevel on which the lidar sensor (11) is mounted. Laser processing head (1) according to one of the preceding claims, wherein the laser processing head (1) comprises a module (20) which contains the at least one lidar sensor (11) and is arranged between the housing (2) and a nozzle (8) of the laser processing head (1). Laser processing head (1) according to one of the preceding claims, wherein the lidar sensor (11) comprises a protective glass (10) and/or a crossjet device for protection against contamination. Laser processing head (1) according to one of the preceding claims, wherein the lidar sensor (11, 12, 13) comprises a ToF-based sensor, AMCW sensor or an FMCW sensor, and/or wherein the lidar sensor (11, 12, 13) is configured for spatially resolved detection of distances and/or wherein the lidar sensor (11, 12, 13) is a lidar camera. Laser processing head (1) according to one of the preceding claims, wherein the at least one lidar sensor comprises a first lidar sensor (11) with a first detection space (111) and a second lidar sensor (12) with a second detection space (121), wherein an angle between the central axis of the detection space (114) of the first lidar sensor (11) and the optical axis of the focusing optics (9) is greater than an angle between the central axis of the detection space of the second lidar sensor (12) and the optical axis of the focusing optics (9). Laser processing head (1) according to Claim 9 , wherein the first lidar sensor (11) is configured to detect distances with a lower resolution than the second lidar sensor (12). Laser processing head (1) according to one of the preceding claims, wherein the laser processing head (1) comprises a plurality of lidar sensors (11, 12, 13) which are arranged on opposite sides of the housing (2) and/or around the optical axis of the focusing optics (9) on the housing (2). Laser processing head (1) according to one of the preceding claims, wherein the laser processing head (1) comprises a controller for controlling and/or regulating the processing process based on the distance data detected by the at least one lidar sensor (11, 12, 13) and/or for controlling the at least one lidar sensor (11, 12, 13) and/or for evaluating the distances detected by the at least one lidar sensor (11, 12, 13). Laser processing head (1) according to Claim 12 , wherein the collision prevention controller is configured to classify the object as critical or non-critical based on the distance detected by the lidar sensor (12, 13, 14). Laser processing head (1) according to Claim 13 , wherein the control is set up to carry out a measure to prevent a collision with an object classified as critical, and to select the measure depending on the detected distance from at least one of the following: bypassing the object, stopping the machining process, switching off the laser beam (3), and slowing down or stopping a relative movement between the laser processing head (1) and the workpiece (4).

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