Laser processing head with a pivoting unit for switching collimator lenses being monitored

Abstract

A laser machining head (30) comprising: - a beam guiding housing (111) for a laser beam (5) propagating along a beam axis (LA); - a pivoting unit (112) comprising a pivoting axis (41) and a pivoting frame (6) rigidly fixed on the pivoting axis (41) and arranged in the beam guiding housing (111); - an adjustment mechanism (34) by means of which the pivoting unit (112) can be rotated about the pivoting axis (41) relative to the beam guiding housing (111); - at least two collimator lenses (2, 9) fixed on the pivoting frame (6) and which can be brought selectively into the beam axis (LA) of the laser beam (5) by the rotation of the pivoting unit (112); - and at least one focusing lens (102) in the beam axis (LA) of the laser beam (5), characterized in that the laser machining head (30) has a monitoring device (106) by means of which the temperature of the pivoting unit (112) can be measured. The invention provides a laser machining head by means of which, in particular, possible inaccuracies in the laser machining or possible shortening of the service life or damage to the laser machining head at high laser power can be recognized early and, if necessary, prevented.

Description

Technical Field

[0001] This invention relates to a laser processing head, comprising:

[0002] - A beam guiding housing for a laser beam that propagates along the beam axis;

[0003] - A pivoting unit comprising a pivoting shaft and a pivoting frame, the pivoting frame being rigidly fixed to the pivoting shaft and arranged within a beam guide housing;

[0004] - An adjustment mechanism that allows the pivoting unit to rotate about a pivot axis relative to the beam guide housing;

[0005] - At least two collimating lenses, which are fixed to a pivoting frame and can be selectively brought into the beam axis of the laser beam by rotation of the pivoting unit;

[0006] - and at least one focusing lens in the beam axis of the laser beam. Background Technology

[0007] The laser processing head is known from DE 10 2014 209 308 A1.

[0008] Laser processing heads are used in a variety of ways for the finishing of workpieces, such as for cutting or welding workpieces.

[0009] Here, different laser beam diameters are required depending on the processing task. DE 10 2014209 308A1 proposes using a laser processing head with a lens switching system to change the beam diameter. Two collimating lenses of the laser processing head are arranged on a pivotable frame, and these collimating lenses can be selectively pivoted to the beam axis of the laser beam.

[0010] During the use of a laser processing head, reflection and scattering occur to some extent within the head, which can cause it to heat up significantly. Reflection and scattering are particularly caused by contaminants in the laser beam path or by optical components (lenses, protective glass) that, for example, exhibit excessive reflectivity for the laser wavelength due to defective implementation of the anti-reflective layer. Heating of the laser processing head can lead to inaccurate workpiece machining, for example, due to thermal drift at the focal point. Similarly, thermal load can shorten the lifespan of the laser processing head.

[0011] In principle, cooling can stabilize and limit the temperature of the laser processing head during processing. Summary of the Invention

[0012] The objective of this invention is to provide a laser processing head that, in particular, can identify early and, if necessary, prevent potential inaccuracies in laser processing at high laser power or potential shortening of the laser processing head's lifespan or damage.

[0013] This task is accomplished in a surprisingly simple yet effective manner by means of a laser processing head of the type described at the beginning, characterized by having a monitoring device by which the temperature of the pivoting unit can be measured.

[0014] This invention provides a monitoring device for monitoring the temperature of the pivot unit of a laser processing head. The inventors have determined that monitoring the temperature of the pivot unit is highly suitable for monitoring the overall laser processing head, particularly its precision and operational safety. For example, localized operational interference or overheating within the laser processing head, caused by contaminants or protective glass with excessively high reflectivity, can consistently lead to a significant temperature increase in the pivot unit; therefore, monitoring the pivot unit is particularly valuable.

[0015] The pivoting unit, due to its rotatability (and, if necessary, mobility), can be cooled essentially only indirectly, which causes the component to immediately exhibit heat energy introduced by (undesirably high) scattering or reflection due to rapid temperature rise.

[0016] If an abnormally high or excessively high temperature is recorded in the pivoting unit, corresponding measures can be taken, particularly as a temporary measure, to temporarily (preferably automatically) cut off the laser beam. This reliably prevents damage or even destruction of the laser processing head. If necessary, other measures can also be taken, such as cleaning the laser processing head and / or replacing (no longer) adequately good optical components, to reduce the scattering and / or reflection of laser radiation in the laser processing head. Within the framework of this invention, the thermal load on the laser processing head can generally be reduced by means of the aforementioned measures.

[0017] In principle, the temperature of the pivoting unit can be monitored using any type of temperature sensor. Preferably, the temperature monitoring of the pivoting unit is performed non-contactly.

[0018] Preferably, the adjusting mechanism allows the pivoting unit to move relative to the beam guide housing in a direction parallel to the beam axis, particularly to adjust the distance between the collimating lens and the exit end of the optical fiber. For this purpose, the laser processing head can be designed such that the adjusting mechanism includes:

[0019] - A slider movable relative to the beam guide housing, wherein a pivot axis is rotatably supported on the slider;

[0020] - A motorized pin that moves in and out without moving with the slider; and

[0021] - A coupling device constructed or fixed on a pivoting unit, the coupling device including a fork or elongated hole, into which a pin can be moved and out of the fork or elongated hole.

[0022] Preferred embodiment of the laser processing head according to the present invention

[0023] In a preferred embodiment of the laser processing head according to the invention, a monitoring device measures the local temperature on the pivot frame. The pivot frame is arranged near (and typically around) the beam axis of the laser beam, thus making it particularly significant as a central component of the entire laser processing head. The pivot frame is coupled, in particular, to any possible cooling device via a solid heat conduction path, specifically through the pivot axis. This makes monitoring the pivot frame particularly important; furthermore, the pivot frame is especially susceptible to overheating hazards.

[0024] The following embodiments are particularly preferred, wherein the monitoring device has a non-contact temperature sensor, particularly a thermopile sensor. This significantly simplifies temperature measurement of the pivoting unit; electrical connections via a rotation mechanism (or even a rotation and movement mechanism) are unnecessary. Furthermore, non-contact measurement saves space compared to tactile measurement, especially for the pivoting unit itself. Thermopile sensors have proven particularly effective in practice.

[0025] In a preferred further embodiment, the non-contact temperature sensor is positioned to point at a blackened measuring surface on the pivoting unit, particularly where the pivoting unit is further wholly or partially gold-plated. The blackened measuring surface improves the measurement of thermal radiation from the pivoting unit. Specifically, the (local) emissivity can be increased to 0.7 or higher, preferably 0.8 or higher, and particularly preferably 0.9 or higher. The additional gold coating on the pivoting unit minimizes the absorption of high-energy, long-wavelength thermal radiation in the pivoting shaft and frame; the thermal radiation increasingly enters the more easily cooled beam guide housing. Preferably, the blackened measuring surface is formed in the region of the pivoting shaft's axis of rotation, so that the rotational position of the pivoting unit does not affect the position of the blackened measuring surface, which further simplifies temperature measurement.

[0026] Particularly preferably, the blackened measurement surface is produced by black marking using an ultrashort pulse laser. This black marking produces a black, gas-free, and very smooth measurement surface, which is also easy to clean, especially in cleaning facilities.

[0027] The following embodiment is particularly preferred, wherein the scattered laser radiation in the beam guide housing can also be measured in the region of the pivoting unit using a monitoring device. Compared to the rather slow temperature measurement, the measurement of scattered laser radiation (including reflected laser radiation) using a photoelectric sensor (e.g., a photodiode) is very fast, thus enabling very rapid identification of high or excessively high scattered light intensities (e.g., due to sudden contamination). This allows for a reaction before potentially damaging heat buildup occurs in the laser processing head (e.g., by cutting off the laser beam). The monitoring device can have a test light source, particularly an LED, by which the monitoring device's function in detecting scattered laser light can be tested. The combination of temperature measurement and scattered light measurement allows for particularly reliable monitoring of the laser processing head.

[0028] The following further embodiment is preferred, wherein the monitoring device has a photoelectric sensor that is directly or indirectly pointed to the pivot frame, particularly the interior space of the pivot frame. In the region of the pivot frame arranged near the beam axis, particularly within the pivot frame, it is desirable that there are virtually no shadows and that scattered (and reflected) laser light can be monitored in a particularly meaningful manner.

[0029] The following further embodiment is advantageous, wherein the beam guide housing has a hole into which a light conductor can be inserted and sealed, and the scattered laser radiation can be measured through the light conductor by means of a monitoring device. This allows the photoelectric sensor and related electronic devices to be arranged separately from the laser beam on the outside of the beam guide housing. It also allows the internal space of the beam guide housing to remain particularly neat.

[0030] In a preferred embodiment, the laser processing head has a first cooling unit and a second cooling unit. The first cooling unit is arranged between a lower portion and an upper portion of the beam guide housing. The lower portion includes at least one focusing lens, a protective glass, and a laser emission nozzle. The upper portion includes a monitoring device and a pivoting unit. The second cooling unit is arranged outside the upper portion of the beam guide housing. The first cooling unit can absorb heat from the lower portion of the laser processing head; this can include not only internally generated heat (due to reflection and / or scattering on the optical elements there), but also energy absorbed from the workpiece processing process (e.g., cutting), the surrounding environment, or from the externally absorbed energy from the laser emission nozzle. The second cooling unit primarily dissipates internally generated heat (directly from the upper portion of the beam guide housing and indirectly through thermal radiation from the pivoting unit where the collimating lens is arranged). With these two cooling units, relatively high laser power can be used overall without excessive overheating of the laser processing head. It should be noted that the first cooling unit can also alternatively be installed in the lower portion of the beam guide housing, dividing the lower portion into a lower section and an upper section, and insulating these sections from each other.

[0031] The following further embodiment is preferred, wherein the first cooling unit is constructed substantially in a plate shape and extends over the entire cross-section of the beam guide housing perpendicular to the beam axis, except for the through-hole for the laser beam. This largely prevents heat input from the lower to the upper portion and reduces heat input only to the difficult-to-cool pivoting unit.

[0032] The following further options are also advantageous, and these further options are designed to...

[0033] The second cooling unit is specifically arranged opposite the adjustment mechanism on the side of the beam guide housing.

[0034] Furthermore, the second cooling unit overlaps at least a portion of the pivoting frame in the direction of the beam axis, and preferably also at least a portion of the corresponding collimating lens pivoting into the beam axis. This arrangement has proven to be particularly efficient and, in particular, effectively absorbs thermal radiation from the pivoting unit and the activated collimating lens. The arrangement of the second cooling unit relative to the adjustment mechanism is particularly compact. To further improve efficiency, the second cooling unit may also span multiple sides of the beam guide housing, for example, not facing all three sides of the adjustment mechanism.

[0035] Furthermore, the following further embodiment is preferred, wherein the two cooling units are water-cooled, and in particular, wherein the two cooling units are connected in series. Water cooling is efficient and inexpensive. Moreover, the series connection can be set up particularly easily and does not reduce cooling power under sufficient flow conditions.

[0036] Furthermore, the following implementation is preferred, wherein the adjustment mechanism includes:

[0037] - Two stops for two rotational positions of the pivoting unit, in which one of the collimating lenses pivots accordingly into the beam axis of the laser beam, and

[0038] - A fixing device, particularly a magnetic fixing device, is used to secure the pivoting unit in these two rotational positions. These two rotational positions can be adjusted accurately and reliably for use with the two collimating lenses.

[0039] The application of the laser processing head described above according to the present invention also falls within the framework of the present invention.

[0040] In this process, a laser beam is input into a laser processing head, and the laser processing head is used to direct the laser beam toward the workpiece to be processed.

[0041] The temperature of the pivoting unit is monitored using a monitoring device. When the temperature of the pivoting unit exceeds a predetermined temperature limit, the laser beam is cut off. This reliably avoids damage to the laser processing head and generally extends its lifespan. It also prevents inaccurate workpiece processing. Laser processing can resume when the temperature drops significantly again, for example, below another temperature limit, and / or when measures have been taken to reduce laser beam scattering or reflection, such as cleaning the laser processing head or replacing unusable optical components.

[0042] Variations of the application according to the invention are also advantageous, wherein the intensity of the scattered laser light in the beam guide housing is also monitored by means of a monitoring device, wherein the laser beam is also cut off when the measured intensity of the scattered laser light exceeds a predetermined scattered light limit. By monitoring the scattered laser light (including reflected laser light), more reliable monitoring of the laser processing head and generally faster detection of operational interference can be achieved. The following variations are also advantageous, wherein different measures are triggered depending on whether the limit value is exceeded by only one sensor or by two different sensors.

[0043] Other advantages of the invention become apparent from the specification and drawings. Similarly, the features described above and further embodied can be used individually or in any combination thereof according to the invention. The illustrated and described embodiments should not be construed as a final enumeration, but rather as having exemplary features for describing the invention. Attached Figure Description

[0044] Figure 1A simplified first embodiment of the laser processing head according to the present invention is shown in schematic longitudinal section;

[0045] Figure 2a A schematic longitudinal section shows a specific second embodiment of the laser processing head according to the invention in the upper part of the beam guide housing;

[0046] Figure 2b A schematic perspective view shows the first cooling unit for a laser processing head according to the invention;

[0047] Figure 3 A schematic perspective view of a third embodiment of the laser processing head according to the present invention is shown;

[0048] Figure 4 A schematic three-dimensional diagram illustrates the area of ​​the lens switching system used for the collimating lens. Figure 3 A laser processing head in which the housing is partially removed;

[0049] Figure 5 Show Figure 4 A schematic cross-sectional view of a lens switching system without a short-stroke cylinder;

[0050] Figure 6 Show Figure 4 A schematic top view of the lens switching system;

[0051] Figure 7 A schematic 3D diagram is shown. Figure 4 Having relative Figure 4 Laser processing head for fork-shaped parts rotated 90°. Detailed Implementation

[0052] Figure 1 An exemplary first embodiment of the laser processing head 30 according to the present invention is illustrated in a schematic longitudinal cross-sectional view. The laser processing head 30 is configured herein as a cutting head for cutting a workpiece to be processed, such as a sheet metal.

[0053] Within the beam guide housing 111, a laser beam (not specifically shown) can propagate along the beam axis (also referred to as the laser beam axis) LA. The divergent laser beam, entering from above, is collimated by the collimating lens 2, focused by the focusing lens 102, and after passing through the protective glass 109 and the laser emission nozzle (also simply referred to as the nozzle) 36, is directed onto the workpiece to be processed (not specifically shown) located below the laser processing head 30.

[0054] Collimating lens 2 is fixed to a pivot frame 6, which is rigidly fixed to a pivot axis 41 that is rotatable about a rotation axis DA. The pivot frame 6 and pivot axis 41 together are referred to as pivot unit 112. The rotation axis DA extends perpendicularly to the beam axis LA. Another collimating lens 9 is also fixed to the pivot frame 6, arranged to rotate 90° relative to collimating lens 2 (about the rotation axis DA). Accordingly, the collimating lenses 2 and 9 in the beam path or in the beam axis LA of the laser beam can be switched by rotation of pivot unit 112 (“lens switching system”).

[0055] A pivoting unit 112 is arranged in the upper portion 33 of the beam guide housing 111. A focusing lens 102 and a protective glass 109 are arranged in the lower portion 35 of the beam guide housing 111, and a nozzle 36 is also constructed on this lower portion. A plate-shaped first cooling unit 101, oriented perpendicular to the beam axis LA, is arranged between the upper portion 33 and the lower portion (see also [reference needed]). Figure 2b ).

[0056] The laser processing head 30 has a monitoring device 106, which monitors the normal operation of the laser processing head 30.

[0057] The monitoring device 106 has a non-contact temperature sensor 107, i.e., a thermopile type, which points to the blackened measuring surface 110 on the pivot frame 6. The temperature sensor 107 measures the thermal radiation from the measuring surface 110, from which the temperature of the pivot unit 112 can be inferred. The temperature sensor 107 and the blackened measuring surface 110 are arranged in the region of the rotation axis DA (preferably on this axis), so that the temperature sensor always points to the blackened measuring surface 110 regardless of the rotational position of the pivot unit. In addition to the blackened measuring surface 110, the surfaces of the pivot frame 6 and the pivot shaft 41 (provided they are located inside the beam guide housing) are gold-plated.

[0058] Furthermore, the monitoring device 106 here includes a photoelectric sensor 108 (e.g., a photodiode) that points inward to the interior of the upper portion 33 of the beam guide housing 111 and, in particular, at least to a portion of the pivoting frame 6. Therefore, the photoelectric sensor 108 primarily monitors the scattered laser (including reflected laser) in the collimated region of the laser processing head 30. The photoelectric sensor 108 is positioned approximately at the height of the collimating lens 2 pivoting into the beam axis LA and faces the collimating lens.

[0059] The photoelectric sensor 108 can record the scattered or reflected laser light inside the upper portion 33 of the beam guide housing 111. High scattered light intensity will, in principle, cause the laser processing head 30 to gradually heat up and is an indication of abnormal operation of the laser processing head 30, for example, due to contamination in the laser processing head 30 or due to the installation of an unsuitable protective glass 109 that excessively reflects the laser wavelength used. Abnormal operation can be identified early by the photoelectric sensor 108 through the monitored scattered light intensity, especially before damage due to excessive heating.

[0060] The monitoring device 106 is arranged on the back side 113 of the beam guide housing 111, which is opposite to the side of the beam guide housing 111 where the pivot shaft 41 is guided into the beam guide housing 111, i.e., where the adjustment mechanism is arranged.

[0061] A second cooling unit 103 is arranged on one of the sides of the beam guide housing 111 parallel to the beam axis LA, and here on the back side 113. The second cooling unit largely overlaps with the pivot frame 6 with respect to the beam axis LA, and also overlaps with the collimating lens 2 pivoted in the beam axis LA. Furthermore, the second cooling unit 103 overlaps with the monitoring device 106.

[0062] The first cooling unit 101 and the second cooling unit 103 can keep the thermal load on the pivot frame 6, the collimating lenses 2 and 9 supported on the pivot frame, and the base of the collimating lenses low, although the pivot unit 112 is not directly but essentially only indirectly cooled (mainly through thermal radiation, and to a lesser extent through gas convection inside the beam guide housing 111 and contact at the bearing of the pivot shaft 41).

[0063] Before the laser processing head 30 is damaged (e.g., due to overheating) and / or the workpiece is processed inaccurately (especially outside the permissible manufacturing tolerances, "scrapped"), abnormal operation of the laser processing head 30 can be determined by means of the monitoring device 106, particularly when the temperature of the pivot unit 112 exceeds a predetermined temperature limit or the intensity of the scattered (including reflected) laser exceeds a predetermined scattered light limit. For this purpose, the monitoring device 106 can be connected to an electronic control device or machine control device (not specifically shown) that automatically cuts off the laser beam when abnormal operation of the laser processing head 30 is determined by means of the monitoring device 106. Additionally, an alarm message can be issued to prompt maintenance (especially cleaning) or repair of the laser processing head 30; the alarm message can be implemented acoustically, optically, or electronically.

[0064] Figure 2aAlso shown schematically in longitudinal section is a second embodiment of the laser processing head 30 according to the invention in the region of the upper portion 33 of the beam guide housing 111. Only the embodiment relative to... Figure 1 The main distinctive features of the illustrative implementation.

[0065] The pivoting unit 112 is supported by a pivoting shaft 41 in a ball bearing 115 within the beam guide housing 111. The second cooling unit 103 is provided with a cooling water line 116.

[0066] The photoelectric sensor 108 of the monitoring device 106 is also arranged outside the beam guide housing 111, just like the electronic devices of the monitoring device 106. A hole 116 is introduced into the beam guide housing 111, and the light conductor 117 is bonded to the hole; the photoelectric sensor 108 faces the rear end of the light conductor 117. This allows the interior of the radiation guide housing 111 to remain particularly simple.

[0067] Temperature sensor 107 is placed in the through opening 118 of beam guide housing 111 and sealed with resilient seal 119. Temperature sensor 107 faces a blackened measuring surface 110, which is produced by means of so-called black marking using an ultrashort pulse laser. The measuring surface 110, structured in this way, is black (with a thermal emissivity of 0.7 or greater), does not release gases, and is also very smooth (e.g., with an average roughness Ra of 1 μm or less) and is therefore easy to clean. Temperature of pivoting unit 112 is monitored non-contactly by means of temperature sensor 107.

[0068] In the illustrated embodiment, the optical conductor 117 also faces the blackened measurement surface 110 with its front end; however, this is not necessary for all positions of the pivoting unit 112.

[0069] Figure 2b The first cooling unit 101 is shown, for example, the first cooling unit can be used in, for example, Figure 1 The laser processing head 30 according to the present invention is shown.

[0070] It is installed between the upper part 33 and the lower part 35 of the beam guide housing 111 (see Figure 1 ) or installed inside the lower part 35 (see Figure 3The first cooling unit 101 is constructed almost in a plate shape and is water-cooled, see cooling water line 116. Except for the through-hole 120 for the laser beam, the first cooling unit 101 occupies the entire cross-section of the laser processing head perpendicular to the beam axis. Furthermore, the first cooling unit 101 is made of metal (e.g., copper or steel), thereby providing good thermal conductivity in the plate plane. This allows the beam guide housing or the lower and upper portions of the laser processing head (or the lower section 35u and the upper section 35o and upper portion 33 of the lower portion 35, see...) to... Figure 3 They are largely thermally isolated from each other. The heat released or input in the lower part (or in the lower section 35u of the lower part 35, for example, adjacent to the nozzle 36) contributes only a small amount to the heating of the difficult-to-cool pivot unit in the upper part. The pivot unit and the collimating lens arranged thereon can thus be well protected or operate at low temperatures.

[0071] Typically, the first cooling unit 101 and the second cooling unit 103 are supplied with cooling water in series (not shown).

[0072] Figures 3 to 7 The laser processing head 30 according to the invention in the third embodiment is shown, wherein the mechanical function of the lens switching system 76 is mainly shown, wherein the rotation and axial movement of the pivot frame can be realized in the illustrated embodiment.

[0073] Figure 3 A schematic external view shows a laser processing head 30. The laser processing head includes a connector 31 for an optical fiber 32, one end of which is disposed in the connector, and a diverging laser beam exits from the connector. Figure 3 (The middle is obscured).

[0074] The laser processing head 30 also includes a beam guide housing 111 with an upper housing portion 33. In the illustrated embodiment, a pivot frame (also simply referred to as the frame) of the lens switching system is housed in this upper housing portion, and two collimating lenses are held on this pivot frame. The laser beam propagating in the upper housing portion 33 (also simply referred to as the upper portion) is guided by collimating lenses located in the beam path. Figure 3 (The center is obscured) and aligned. A motion mechanism system (also called an adjustment mechanism) 34 is arranged on the upper housing portion 33, by means of which the pivot frame can be rotated and moved within the upper housing portion 33.

[0075] The beam guide housing 111 of the laser processing head 30 also includes a lower housing portion 35, in which a focusing lens is disposed, which focuses the laser beam propagating in the lower housing portion 35 (in... Figure 3(The middle is also blocked). A nozzle 36 is installed at the lower end of the lower housing portion 35 (also referred to as the lower portion), by means of which the area of ​​the workpiece being processed by the laser beam is subjected to a gas flow, such as a cutting gas flow to expel the melt from the cutting gap and / or an inert gas flow to prevent oxidation on the workpiece. The workpiece is positioned below the nozzle 36 (not specifically shown). In the illustrated embodiment, a first cooling unit 101 is also installed inside the lower portion 35, thereby dividing the lower portion 35 into a lower section 35u and an upper section 35o and insulating the lower section and the upper section from each other.

[0076] It should be noted that in the laser processing head 30 according to the invention, the beam path of the laser beam up to the nozzle 36 is completely closed. To allow the frame to rotate or move within the upper housing portion 33 (i.e., to switch or adjust the collimating lens), it is not necessary to open the beam path (particularly the housings 33, 35).

[0077] Figure 4 , Figure 5 and Figure 6 Show in detail Figure 3 The area of ​​the upper housing portion 33 of the laser processing head 30 and the motion mechanism system (adjustment mechanism) 34, wherein some covers have been removed for better understanding. The motion mechanism system (adjustment mechanism) 34, together with the lens-carrying frame (pivoting frame) 6, can be referred to as the lens switching system 76.

[0078] According to the present invention, the laser processing head 30 has a monitoring device 106, which includes a temperature sensor 107 for monitoring temperature, the temperature sensor pointing towards the blackened measuring surface 110 of the pivot frame 6. The monitoring device 106 also includes a photoelectric sensor 108, which points towards the interior of the upper portion of the beam guide housing or towards the pivot frame 6 to measure the scattered and reflected laser light (only in…). Figure 5 (as shown in the image).

[0079] A laser beam 5, emitted from the end 40 of optical fiber 32, passes through the generally cubic frame 6, wherein the laser beam 5, within the frame 6, is as follows: Figure 5 and Figure 6 In the rotational position shown, collimation is achieved by a collimating lens 9 with a long focal length on the lower side of frame 6. A collimating lens 2 with a short focal length is also maintained in frame 6, see [link to documentation]. Figure 6 By rotating frame 6 about its centrally extending axis of rotation DA in pivot axis 41, the collimating lenses 9 and 2 in the beam path of laser beam 5 can be switched. Specifically, this can be achieved by rotating frame 6 from... Figure 6 Starting from the rotational position, rotate 90° clockwise to bring the collimating lens 2 into the laser beam 5, thereby arranging the collimating lens on the upper side of the frame 6 (the latter is not shown, but see...). Figure 7 (The rotated position). In the illustrated embodiment, the rotation axis DA extends through the intersection point 10 of the optical axes OA1 and OA2 of the collimating lenses 2 and 9, where the optical axes intersect at an angle of 90°.

[0080] The pivot frame 6 is rigidly connected to the pivot shaft 41; together they constitute the pivot unit 112. The pivot shaft 41 is rotatably and without clearance supported on the slider 42 about axis DA. The slider 42 can be moved linearly along the z-direction, parallel to the laser beam axis (also referred to as the beam axis) LA, by a motor 43 driving the ball screw 44, and for this purpose is supported without clearance on at least one guide rail 54 of the laser processing head 30. By moving the slider 42 together with the pivot unit 112, the focal position of the pivoted (activated) collimating lenses 2, 9 can be adjusted.

[0081] In the illustrated embodiment, the frame 6 can also be rotated by means of a motor 43 that drives the slider 42. For this purpose, a fork-shaped member 45 is arranged at the rear end of the pivot shaft 41, and the pin 46 of the short-stroke cylinder 47 can engage with this fork-shaped member (only when...). Figure 4 (As shown in the diagram). The fork 45 and pin 46 are radially spaced apart from the axis of rotation DA. The pin 46 can be moved into and out of the fork 45 along a pin axis BA parallel to the axis of rotation DA by means of a short-stroke cylinder 47. The short-stroke cylinder 47 is typically rigidly fixed to the laser processing head 30 and, in particular, does not move with the slider 42.

[0082] Once pin 46 is removed from fork 45, the slider 42 and the frame 6 can be moved along the z-direction by means of motor 43 to change the focal position of laser beam 5 on the workpiece, without affecting the rotational position of frame 6.

[0083] When pin 46 moves into fork 45, the pivot 41 can also rotate due to the linear movement of slider 42 and the movement of the pivot 41 to which fork 45 is fixed. For example, in frame 6 or fork 45... Figure 4 When slider 42 moves downward at the indicated rotational position, pin 46, which does not move with slider 42, forces pivot 41 to rotate counterclockwise along with fork 45. Note that pin 46 moves along fork 45 relative to fork 45 in this position. Figure 7 Show Figure 4 After the slider 42 moves downward along the z-direction into the fork 45 with the pin 46 in place, the laser processing head rotates 90°, thereby rotating the fork 45 (and thus the pivot and frame 6 as well).

[0084] It should be noted that in order to move the pin 46 into the fork 45, i.e. to prepare for switching the lens, it is necessary to first move the slider 42 to the z position, in which the fork 45 is opposite the pin 46.

[0085] As from Figure 4 and Figure 7 As can be best seen, two abutment elements 48, 49 are also constructed on the rear end of the pivot 41, by means of which the final position of the pivot 41 is defined and fixed. Figure 4 In the rotational position shown, the abutment element 48 abuts against the stop 50 of the slider 42. The abutment element 48 is magnetic and thus serves as a fixing device 52 for the ferromagnetic (or equally magnetic) stop 50. The abutment element 49, which is also magnetic and therefore also serves as a fixing device 53, can abut against and be fixedly held against the ferromagnetic (or equally magnetic) stop 51 of the slider 42 after the pivot shaft 41 has pivoted, as... Figure 7 As shown in the diagram. The two rotational positions of the pivot axis 41, defined by the stops 50 and 51, are 90° apart from each other, which corresponds to the angle between the optical axes OA1 and OA2 of the collimating lenses 2 and 9.

[0086] The selection of the lens on the frame 6 (i.e., the rotational position of the pivot axis 41) and the z-position of the lens used (i.e., the movement position of the slider 42 about the z-direction) can be achieved by the machine control device, for example, through a stored parameter table, without operator intervention, thereby automatically selecting and adjusting the matching imaging ratio and matching focal position of the laser beam 5 when selecting the workpiece to be processed (typically a sheet metal).

[0087] List of reference numerals

[0088] 2. Collimating lens

[0089] 5. Laser beam

[0090] 6 Pivoting Frames / Frames

[0091] 9. Collimating lens

[0092] 10 intersections

[0093] 31 Connector

[0094] 32 optical fibers

[0095] 33 Upper shell section / upper part

[0096] 34. Motion mechanism system / adjustment mechanism

[0097] 35 Lower housing section / lower part

[0098] 35° lower shell section / upper section of the lower part

[0099] 35u lower housing section / lower section of the lower part

[0100] 36 laser emission nozzles / nozzles

[0101] 40. End of optical fiber

[0102] 41 Pivot axis

[0103] 42 sliders

[0104] 43 motors

[0105] 44 Ball Screw

[0106] 45 Fork-shaped parts

[0107] 46 sales

[0108] 47 Short-stroke cylinder

[0109] 48. Attached components

[0110] 49. Attached components

[0111] 50 Stop

[0112] 51 Stop

[0113] 52 Fixing device

[0114] 53 Fixing device

[0115] 54 guide rails

[0116] 76 Lens Switching System

[0117] 101 First Cooling Unit

[0118] 102 Focusing Lens

[0119] 103 Second Cooling Unit

[0120] 106 Monitoring Device

[0121] 107 Temperature Sensor

[0122] 108 photoelectric sensor

[0123] 109 Protective Glass

[0124] 110 The blackened measuring surface

[0125] 111 Beam Guide Housing

[0126] 112 Pivot Unit

[0127] 113 Dorsal side

[0128] 115 ball bearing

[0129] 116 holes

[0130] 117 Optical Conductor

[0131] 118 through-hole (for thermopile)

[0132] 119 Resilient Seal

[0133] 120mm through-hole (second cooling unit)

[0134] BA pin axis

[0135] DA rotation axis (pivoting unit)

[0136] LA laser beam axis / beam axis

[0137] OA1 optical axis (collimating lens 2)

[0138] OA2 optical axis (collimating lens 9).

Claims

1. A laser processing head (30), comprising: - Beam guide housing (111) for a laser beam (5) that propagates along the beam axis (LA). - A pivoting unit (112), the pivoting unit comprising a pivoting shaft (41) and a pivoting frame (6), the pivoting frame being rigidly fixed to the pivoting shaft (41) and arranged in the beam guide housing (111); - Adjustment mechanism (34), by means of which the pivoting unit (112) can be rotated about the pivot axis (41) relative to the beam guide housing (111); - At least two collimating lenses (2, 9) are fixed on the pivot frame (6) and can be selectively brought into the beam axis (LA) of the laser beam (5) by rotation of the pivot unit (112); - and at least one focusing lens (102) in the beam axis (LA) of the laser beam (5), characterized in that, The laser processing head (30) has a monitoring device (106) by means of which the temperature of the pivoting unit (112) can be measured. The monitoring device (106) measures the local temperature on the pivot frame (6). The monitoring device (106) has a non-contact temperature sensor (107). The non-contact temperature sensor (107) is positioned on a blackened measuring surface (110) on the pivot frame (6), and the blackened measuring surface (110) is located in the region of the rotation axis DA of the pivot shaft (41). The pivoting unit (112) is further plated entirely or partially with gold. The laser processing head (30) has a first cooling unit (101) and a second cooling unit (103). The first cooling unit (101) is arranged between the lower part (35) of the beam guide housing (111) and the upper part (33) of the beam guide housing (111). The lower part includes the at least one focusing lens (102), a protective glass (109) and a laser emission nozzle (36). The upper part includes the monitoring device (106) and the pivoting unit (112). The second cooling unit (103) and the adjustment mechanism (34) are arranged opposite each other on the side of the beam guide housing (111). Furthermore, the second cooling unit (103) overlaps at least a portion of the pivot frame (6) in the direction of the beam axis (LA).

2. The laser processing head (30) according to claim 1, characterized in that, The blackened measuring surface (110) is arranged on the rotation axis DA of the pivot shaft (41).

3. The laser processing head (30) according to claim 1, characterized in that, The non-contact temperature sensor (107) is a thermopile sensor.

4. The laser processing head (30) according to any one of claims 1 to 3, characterized in that, The blackened measurement surface (110) is produced by black marking with the aid of an ultrashort pulse laser.

5. The laser processing head (30) according to any one of claims 1 to 3, characterized in that, The monitoring device (106) also enables the measurement of laser radiation scattered in the beam guide housing (111) in the region of the pivot unit.

6. The laser processing head (30) according to claim 5, characterized in that, The monitoring device (106) has a photoelectric sensor (108) that points directly or indirectly at the pivot frame (6).

7. The laser processing head (30) according to claim 6, characterized in that, The photoelectric sensor (108) points directly or indirectly into the interior space of the pivot frame (6).

8. The laser processing head (30) according to claim 5, characterized in that, The beam guide housing (111) has a hole (116), into which a light conductor (117) is inserted and sealed, and the scattered laser radiation can be measured through the light conductor (117) by means of the monitoring device (106).

9. The laser processing head (30) according to claim 1, characterized in that, The first cooling unit (101) is plate-shaped and extends over the entire cross section of the beam guide housing (111) perpendicular to the beam axis (LA), except for the through-hole (120) for the laser beam (5).

10. The laser processing head (30) according to claim 1, characterized in that, The second cooling unit (103) overlaps at least a portion of the collimating lens (2, 9) pivoted in the beam axis (LA) in the direction of the beam axis (LA).

11. The laser processing head (30) according to claim 1, characterized in that, The two cooling units (101, 103) are cooled by water.

12. The laser processing head (30) according to claim 11, characterized in that, The two cooling units (101, 103) are connected in series.

13. The laser processing head (30) according to any one of claims 1 to 3, characterized in that, The adjustment mechanism (34) includes: - Two stops (50, 51) for two rotational positions of the pivoting unit (112), in which one of the collimating lenses (2, 9) is correspondingly pivoted into the beam axis (LA) of the laser beam (5), and - Fixing devices (52, 53) are used to fix the pivoting unit (112) in the two rotational positions.

14. The laser processing head (30) according to claim 13, characterized in that, The fixing devices (52, 53) are magnetic fixing devices (52, 53).

15. An application of the laser processing head (30) according to any one of claims 1 to 14, in, A laser beam (5) is input into the laser processing head (30), and the laser processing head (30) is used to direct the laser beam toward the workpiece to be processed. The temperature of the pivoting unit (112) is monitored by means of the monitoring device (106). When the temperature of the pivoting unit (112) exceeds a predetermined temperature limit, the laser beam (5) is cut off.

16. The application according to claim 15, in, The intensity of the scattered laser light in the beam guide housing (111) is also monitored using the monitoring device (106). When the measured intensity of the scattered laser exceeds a predetermined scattering limit, the laser beam is also cut off (5).

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