Laser processing apparatus and laser processing method for processing workpieces

Abstract

A laser processing apparatus and a laser processing method for processing a workpiece are described. The laser processing apparatus includes a laser processing head (100), which has a housing (102) having an interface (107) for connecting a laser light source for a processing laser beam (104) and an exit aperture (108) for the processing laser beam (104), and an optical system (103) for shaping the processing laser beam and guiding the processing laser beam (104) onto an optical path (30) having the entire length between the interface (107) and the exit aperture (108). The optical system (103) includes first and second fixed deformable mirrors (21a, 21b), each of which is arranged to deflect the processing laser beam at an angle (α1, α2). The ratio of the total length of the optical path (30) between the exit aperture (108) and the interface (107) for connecting the laser light source to the spatial extension (D) of the housing (102) parallel to the central axis (A) of the exit aperture (108) is in the range of 2 to 4.5.

Description

Technical Field

[0001] The present invention relates to a laser processing apparatus for laser processing a workpiece, a laser processing method for laser processing a workpiece, and a computer program product.

Background Art

[0002] Lasers, particularly solid-state lasers such as fiber lasers or disk lasers, are increasingly being used for processing metallic materials. Laser light sources with a maximum output of 50 kW or more are being used. The main laser processing of metallic materials is cutting, welding, hardening, and additive manufacturing. In material processing, laser irradiation is directed to a processing position, also called a processing area, on the workpiece and shaped for processing. In some laser processing apparatuses, laser irradiation is guided to the processing head of the laser processing apparatus via a transmission fiber. The processing head is guided onto the workpiece during processing and typically undergoes large accelerations. Therefore, a compact design of the processing head is desired. In particular, in the irradiation direction of the processing laser beam onto the workpiece, the available space may be limited, for example, by the height of the machine or the processing cell.

[0003] The processing head is typically arranged close to the hot processing area during processing of the workpiece and is constantly exposed to the possibility of contamination by fine contamination particles generated by the processing. On the other hand, the laser beam is shaped for the intended processing in the processing head. This can typically be done with a free beam, i.e., a beam propagating in a gaseous environment or in a vacuum. A free-beam laser beam using lenses commonly used for beam shaping is particularly sensitive to contamination. Even slight contamination of the lens surface can lead to a malfunction of the processing head due to the high laser output used. Contamination can occur not only from the outside but also from the inside of the processing head. When lenses or other optical elements are adjusted for focus position adjustment or magnification change, wear due to contaminants may occur due to mechanical movement.

[0004] In this context, the term "magnification" refers to the optical magnification ratio between the laser beam exiting the processing head and the laser beam entering the processing head. When the laser beam is guided from the laser light source to the processing head in an optical waveguide, such as a transmission fiber, the diameter of the laser beam when it enters the processing head is equal to the diameter of the light guide. In this case, the magnification of the processing head, i.e., the magnification of the processing head's optical system, represents the magnification ratio of the diameter of the laser beam at the exit aperture of the processing head to the diameter of the optical waveguide.

[0005] A typical laser processing head 1 is schematically shown in Figure 1 and includes a transmission fiber 2, displaceable lenses 5a, 5b, lens displacement mechanisms 3a, 3b, a laser beam 4 provided as a free beam, a workpiece 12 to be processed, an exit aperture 8, and a processing position 7. In some examples, the interior of the processing head 1 is shielded with optional replaceable protective glass 9. This protective glass protects the high-sensitivity optical unit of the processing head from contamination. The basic structure shown in Figure 1 corresponds to a typical and widely used processing head. The basic magnification setting is configured using the focal length ratio of the focusing lens 5b and the collimating lens 5a. The focal length ratio of the focusing lens 5b and the collimating lens 5a may be in the range of, for example, 2 to 3.4. By displacing the lenses 5a, 5b parallel to the propagation direction of the laser beam 4, the magnification and / or focal position of the laser beam can be changed with respect to the exit aperture 8. The processing head may include more than two lenses. For a processing head where both magnification and focal position can be changed, typically at least two lenses are designed to be displaceable. It should be noted that not all machining heads are designed with magnification adjustment options. On the other hand, the possibility of adjusting the focal position is typically provided in the machining head. This is because the focal position at machining position 7 can affect or determine the machining quality. Depending on the machining parameters, such as the thickness or material of the workpiece, or the composition of the machining gas, other focal positions may be used.

[0006] The processing head shown in Figure 1 has several disadvantages. On the one hand, mechanical wear occurs as optical elements such as lenses 5a and 5b are moved or displaced. This wear can contaminate the optical surface. Furthermore, transmissive optical elements such as lenses 5a and 5b are particularly sensitive to contamination. This is because contaminated areas on the transmissive surface are locally heated very strongly by radiation-absorbing contaminants. This causes a large change in refractive index in this area, resulting in a large refractive index gradient relative to the surrounding area. This locally strong change in light refraction can usually affect the shaping of the laser beam and can render the processing head unusable. Transmissive optical elements, especially commonly used quartz optical units, are difficult to cool and have low thermal conductivity, so they can be locally heated very strongly by contaminants, potentially causing charring of the optical elements.

[0007] Therefore, attempts have been made to develop processing heads without displaceable lenses. LaserMech has developed the FibreCut HR processing head, which does not require moving a transmissive optical element to adjust the focal position (see FibreCUT® HR - Laser Mechanisms, Inc.). The laser beam is directed through a rigid, curved, water-cooled metal mirror. The focal position of this head is adjusted by changing the distance between the exit aperture and the protective glass of the processing head. A further example of a processing head without a movable transmissive optical element is the FC4 laser cutting head from LT Ultra (see 2D (Solid State) - LT Ultra Precision Technology GmbH (lt-ultra.com)). This cutting head uses a mirror with variable mirror curvature. However, in the above example, it is not possible to adjust anything other than the focal position of the processing laser beam. Further examples where it is preferable to omit the transmissive optical unit are well known in Patent Documents 1 and 2, which disclose a reflective optical unit in a cutting head. Patent Document 3 relates to a method, adjustment module, computer program, and system for dynamically adjusting the focal diameter of a laser beam emitted from the laser processing head of a laser cutting machine. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] European Patent Application Publication No. 3747588 [Patent Document 2] European Patent Application Publication No. 3980216 [Patent Document 3] European Patent Application Publication No. 4144474 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The objective is to provide a laser processing apparatus and a laser processing method that allow for changes in the focal position of the processing laser beam and the magnification of the optical system, while avoiding contamination. [Means for solving the problem]

[0010] This objective is achieved by a laser processing apparatus for laser processing a workpiece as described in claim 1, a laser processing method for laser processing a workpiece as described in claim 10, and a computer program product as described in claim 15.

[0011] One embodiment relates to a laser processing apparatus for laser processing, particularly laser cutting, of a workpiece, comprising a laser processing head including a housing having an interface for connecting a laser light source for a processing laser beam and an exit opening for the processing laser beam, and an optical system for shaping the processing laser beam and guiding the processing laser beam into an optical path having a total length between the interface and the exit opening, wherein the housing surrounds the optical system and has a spatial extension parallel to the central axis of the exit opening, the optical system has a first fixed deformable mirror and a second fixed deformable mirror, each of which is arranged and / or designed to deflect the processing laser beam at a predetermined angle, and the ratio of the total length of the optical path between the exit opening and the interface for connecting the laser light source to the spatial extension of the housing parallel to the central axis of the exit opening is in the range of 2 to 4.5, preferably 3 to 4.

[0012] Remarkably, the above embodiment allows for changes in both the focal position of the processing laser beam and the magnification of the optical system, while avoiding contamination of the processing head, particularly the optical system. Changes in both the focal position of the processing laser beam and the magnification of the optical system are performed by the first and second fixed deformable mirrors, without displacing the optical elements and thus avoiding resulting wear. Simultaneously, the processing laser beam can be flexibly shaped by the first and second fixed deformable mirrors. The relatively long optical path between the interface for connecting the laser light source and the exit aperture of the processing head is compensated for by beam folding at the first and second deformable mirrors. Therefore, the spatial expansion of the optical path of the processing laser beam parallel to the central axis of the exit aperture can be reduced by the change in the propagation direction of the processing laser beam. This results in a compact processing head with a small spatial expansion, particularly parallel to the central axis of the exit aperture. In some variations of the embodiment, the ratio of the total length of the optical path to the spatial expansion of the housing parallel to the central axis of the exit aperture may be greater than 2, preferably in the range of 2.1 to 10.

[0013] In all embodiments, the first deformable mirror and / or the second deformable mirror may, in each case, be a mirror with an adjustable radius of curvature, also known as a mirror with a variable radius of curvature or VRM. The first deformable mirror, the second deformable mirror, and at least one mirror selected from at least one further deformable mirror, and / or the radius of curvature of each of them may be dynamically deformable or adjustable at frequencies in the range of 20 Hz to 100 Hz. At least one mirror, in particular the first deformable mirror and / or the second deformable mirror, may each be deformable or adjustable within a few milliseconds, for example, within 1 ms to 200 ms, preferably within 1 ms to 50 ms. The radius of curvature of at least one mirror may be in the range of -1.5 m to +1.5 m, preferably -2.8 m to +2.8 m, more preferably -3 m to +3 m. For example, a full stroke from a radius of curvature of -3 m to a radius of curvature of +3 m, or vice versa, may be achieved in about 20 ms. By using deformable mirrors, particularly mirrors with a variable radius of curvature, low-aberration deflection of the processing laser beam can be achieved.

[0014] In all embodiments, the total length of the optical path may be in the range of 1000 mm to 2500 mm, preferably 1400 mm to 1900 mm. The spatial extension of the housing parallel to the central axis of the exit opening may be in the range of 300 mm to 700 mm, preferably 400 mm to 600 mm. The portion of the optical path between the first deformable mirror and the second deformable mirror may have a length of at least 300 mm, preferably 700 mm to 1100 mm. In modified embodiments, the portion of the optical path between the first deformable mirror, the second deformable mirror, and / or further fixed deformable mirrors, particularly the minimum portion of the optical path, may be 280 mm to 350 mm, preferably 150 mm to 450 mm.

[0015] In all embodiments, the radius of curvature of the first mirror and / or the radius of curvature of the second mirror may be in the range of -1.5m to +1.5m, preferably -2.8m to +2.8m, and more preferably -3m to +3m. This is particularly advantageous for the mechanical properties of the VRM, especially the modulus of elasticity and material fatigue, when the first mirror and / or the second mirror are each designed as VRMs, i.e., mirrors having a variable radius of curvature. Furthermore, the angle at which the first mirror and / or the second mirror deflect the processing laser beam can be less than 90°. This angle can be an acute angle in the range of 5.5° to 12.5°, preferably 7.5° to 10.5°. This enables low aberration deflection. Due to the acute deflection angle, the mirror surface, when deformed, can be deformed to be nearly spherical, thus preventing the introduction of large, undesirable astigmatism and / or aberrations into the processing laser beam.

[0016] The ratio of the spatial extension portion of the housing parallel to the central axis of the exit opening to the length of the optical path portion between the first and second deformable mirrors may be in the range of 0.33 to 0.9, preferably 0.4 to 0.7.

[0017] The first and second deformable mirrors, and in particular the actuators of the first and second deformable mirrors, are designed to be controllable individually and / or in a coordinated manner, allowing for adjustment of the radius of curvature. A control device for controlling the first and second mirrors, and in particular for controlling the actuators of the first and second mirrors, may be provided in the laser processing apparatus. A storage device, in particular for program modules of computer program products, may be provided in the laser processing apparatus and / or the control device.

[0018] The first and / or second deformable mirrors may be deformable so that at least one element selected from the divergence and diameter of the processing laser beam is altered. The housing may include only the optical system. The first and second mirrors may be further designed to reflect and / or deflect at least partially the processing laser beam.

[0019] At least one element selected from the optical system and control device may be designed so that the focal position of the processing laser beam and the magnification of the optical system are changed by adjusting at least one of the radii of curvature of the first and second deformable mirrors, in particular by adjusting only at least one of the radii of curvature of the first and second deformable mirrors. Furthermore, at least one element selected from the optical system and control device may be designed such that the change in curvature of the first and / or second mirrors is at least 2.3 (m × s) -1 It may also be designed to occur in a certain way. In some embodiments, curvature is defined as the reciprocal of the radius of curvature, i.e., 1 / radius of curvature. For example, full stroke is a curvature of -0.3m -1 From curvature +0.3m -1 This can occur in less than 250ms. This results in 2.4(m×s) -1 It changes with curvature.

[0020] At least one element selected from the optical system and control device may be designed such that the focal position of the processing laser beam at the processing position is adjustable in the range of -90 mm to +110 mm, preferably -40 mm to +40 mm, and / or the magnification of the optical system is adjustable in the range of 1.4 to 4.8, preferably 1.7 to 3.8.

[0021] The optical system may include only optical elements that are each fixed, particularly including the propagation direction of the processing laser beam. The optical system may include one or more additional optical elements selected from mirrors, adaptive mirrors, deflecting mirrors, lenses, and fiber end caps, and these optical elements are each fixed. At least one optical element selected from at least one fixed planar mirror, at least one fixed adaptive mirror, and at least one additional fixed deformable mirror may be provided between the first mirror and the second mirror. The optical path portions between at least one additional fixed deformable mirror and at least one adjacent mirror selected from the first fixed deformable mirror, the second fixed deformable mirror, and other additional fixed deformable mirrors may each have a length in the range of 150 mm to a maximum of 450 mm, preferably 280 mm to 350 mm.

[0022] By providing at least one fixed optical element between the first mirror and the second mirror, the optical path between the first mirror and the second mirror can be divided into optical sub-paths. The spatial expansion of the optical path of the processing laser beam parallel to the central axis of the exit aperture can be minimized by further repeated changes in the propagation direction of the processing laser beam, i.e., further beam folding. As a result, despite the long optical path length, a reduction in the overall height of the processing head can be achieved, particularly a reduction in the spatial expansion of the housing parallel and / or perpendicular to the central axis of the exit aperture can be achieved.

[0023] In some variants, the laser light source for the processing laser beam may be connected to the interface. Further, the housing may have further interfaces for connecting further components, particularly cameras for processing monitoring and / or light sources for illumination light.

[0024] A further embodiment relates to a laser processing method for performing laser processing, particularly laser cutting, of a workpiece using a laser processing apparatus according to the foregoing embodiments or a modification thereof, and includes the following steps: generating a processing laser beam using a laser light source connected to an interface of a housing of a laser processing head; shaping the processing laser beam; guiding the processing laser beam on an optical path having an overall length between the interface and an exit opening of the laser processing head using an optical system; adjusting at least one of radii of curvature of a first stationary deformable mirror and a second stationary deformable mirror; deflecting the processing laser beam at a predetermined angle at each of the first deformable mirror and the second deformable mirror; and processing the workpiece using the processing laser beam.

[0025] In this method, the ratio of the overall length of the optical path to a spatial extension of the housing parallel to the central axis of the exit opening can be in the range of 2 to 4.5, preferably 2.5 to 4. The optical path portion between the first and second deformable mirrors can have a length of at least 300 mm, preferably in the range of 700 mm to 1100 mm. An acute angle in the range of 5.5° to 12.5°, preferably 7.5° to 10.5°, can be selected or pre-set as the angle at which the first and / or second mirror deflects the processing laser beam.

[0026] The first and second mirrors, particularly the actuators of the first and second mirrors, are controlled individually and / or in a coordinated manner with each other, particularly in a coordinated manner with a control device, and the radius of curvature can be adjusted. The first and / or second deformable mirror can be deformed, and as a result, at least one element selected from the divergence of the processing laser beam and the diameter of the processing laser beam is changed.

[0027] The focal position of the processing laser beam and the magnification of the optical system can be changed by adjusting at least one of the radii of curvature of the first and second deformable mirrors, and in particular by adjusting only at least one of the radii of curvature of the first and second deformable mirrors. Furthermore, the change in curvature of each of the first and / or second mirrors is at least 2.3 (m × s) -1 This can happen.

[0028] The focal position of the processing laser beam can be adjusted within the range of -90 mm to +110 mm, preferably -40 mm to +40 mm. The magnification of the optical system can be adjusted within the range of 1.4 to 4.8, preferably 1.7 to 3.8. The spatial expansion of the optical path of the processing laser beam parallel to the central axis of the exit aperture can be minimized by repeatedly changing the propagation direction of the processing laser beam.

[0029] One embodiment relates to a computer program product comprising one or more program modules, the program modules causing an apparatus according to the above-described embodiment or a modified thereof to execute the steps of the laser processing method according to the above-described embodiment or a modified thereof, particularly when the program module is loaded into the device's storage device.

[0030] Embodiments or modifications of a laser processing apparatus may be used in embodiments or modifications of a laser processing method for a workpiece. The workpiece comprises at least one metal, i.e., is a metal and / or may have the shape of a metal plate. In the aforementioned embodiments of the laser processing apparatus for a workpiece, the same advantages and functions as embodiments of the laser processing apparatus having the same and / or similar features may be realized.

[0031] It is understood that the features described above and those described below can be used not only in the combinations shown, but also in other combinations or individually, without departing from the scope of the present invention.

[0032] The present invention will be described in detail below based on exemplary embodiments with reference to the accompanying drawings, which also disclose essential features of the invention. These exemplary embodiments are for illustrative purposes only and should not be construed as limiting. For example, the description of an exemplary embodiment having a number of elements or components should not be construed as meaning that all of these elements or components are necessary for implementation. Rather, other exemplary embodiments may also include alternative elements and components, fewer elements or components, or additional elements or components. Elements or components of different exemplary embodiments may be combined with each other unless otherwise specified. Modifications and variations described for one exemplary embodiment may also apply to other exemplary embodiments. To avoid duplication, identical elements or corresponding elements are indicated by the same reference numerals in different figures and are not described more than once. The drawings are described below. [Brief explanation of the drawing]

[0033] [Figure 1] This is a schematic diagram showing a typical laser processing head 1. [Figure 2a] This diagram schematically shows exemplary deformable mirrors in each case. [Figure 2b] This diagram schematically shows exemplary deformable mirrors in each case. [Figure 3a] This diagram schematically shows a laser processing head 100 as an example. [Figure 3b] This diagram schematically shows a laser processing apparatus 10 as an example. [Figure 4] This diagram schematically shows a laser processing head 200 as an example. [Figure 5] This diagram schematically shows a laser processing head 300 as an example. [Figure 6] This figure shows a region 116 in which the magnification and focal position can be adjusted using the laser processing head 100. [Figure 7]This figure shows regions 116a, 116b, and 116c that can be adjusted using the laser processing head 100, whose magnification and focal position have been changed. [Modes for carrying out the invention]

[0034] In any embodiment, its modification, or example, the material of the workpiece may include at least one type of metal. The workpiece may also be formed as a metal sheet. The term “connecting a laser light source” may include direct connection of a laser light source, or connection of optical fibers and / or fiber end caps of optical fibers connected to a laser light source. The laser light source may be designed to produce a processing laser beam with wavelengths in the range of 400 nm to 1500 nm and / or with an output of at least 1 kW, preferably 1 kW to 50 kW. The first fixed deformable mirror may be referred to as the first deformable mirror or the first mirror. The second fixed deformable mirror may be referred to as the second deformable mirror or the second mirror. The term “deformable” may also be referred to as “adjustable.” The term “processing head” may also be used synonymously with the term “laser processing head.”

[0035] Figures 2a and 2b schematically illustrate a deformable mirror 21a as an example, which may be used as a first fixed deformable mirror and / or a second fixed deformable mirror. Figure 3a schematically illustrates a laser processing head 100 as an example, which includes an optical system 103 equipped with two fixed deformable mirrors 21a and 21b. Figure 3b schematically illustrates a laser processing apparatus 10 equipped with the processing head 100 as an example. The processing head 100 has a housing 102, which is provided therein an interface 107 for connecting a laser light source 120 for a processing laser beam 104, and an exit opening 108 for the processing laser beam 104. The interface 107 is located in the lateral region of the end of the housing 102 opposite the exit opening 108.

[0036] In this example, the first mirror 21a and the second mirror 21b are designed as VRMs 21a and 21b, respectively, i.e., mirrors with a variable radius of curvature. Figures 2a and 2b show a schematic representation of the VRM 21a, respectively. The VRM 21b has the same design. Mirror 21a has a movable surface 25, which is designed as a film 26 and deflects the incident processing laser beam 104. In addition, mirror 21a can change the beam divergence of the processing laser beam 104.

[0037] The curvature of the surface 25 of the VRM 21a is changed, for example, by a liquid or gaseous fluid applied to the rear surface of the film 26. An actuator 28 is provided for this purpose. The actuator 28 may be, for example, a pump, controlled by a control device 29 of the processing head 100, and can adjust the pressure of the fluid in the fluid space 27 of the mirror 21a adjacent to the film on the surface 25. Furthermore, a fluid reservoir (not shown) may be connected to the pump. The mirror curvature, i.e., the curvature of the film 26, and thus the radius of curvature of the surface 25, can be dynamically changed by the actuator 28 at a frequency in the range of 20 Hz to 100 Hz. Figure 2a shows a mirror 21a with a concave curvature of the surface 25, and Figure 2b shows a mirror 21a with a convex curvature of the surface 25. The control device 29 may be a central control device of the laser processing apparatus 10, and may be connected to or included in all controllable components by data transmission.

[0038] In the example of VRM 21a shown in Figures 2a and 2b, the processing laser beam 104 is deflected to the surface 25 at a small angle α1, particularly an acute angle α1. In VRM 21b, the processing laser beam 104 is deflected at a small, particularly acute angle α2. This is advantageously achieved by the fact that the processing head 100 shown in Figure 3a may have a long optical path 30 as a beam path due to the limited curvature capabilities of VRMs 21a and 21b, and can be configured compactly. Due to the small, particularly acute angles α1 and α2 between the incident laser beam and the exit laser beam, the processing head 100 has a compact design and a low overall height. This means that the processing head 100 has a small spatial extension D parallel to the central axis A of the exit aperture 108, despite the long optical path between the interface 107 and the exit aperture 108, as indicated by the arrows in Figure 3a. By deforming the surfaces 25 of VRMs 21a and 21b, that is, by changing the radius of curvature of VRMs 21a and / or VRMs 21b, the magnification of the optical system 103 of the machining head 100 can be changed within approximately the range of a basic magnification setting. In this example, optical imaging is substantially determined by the length of the portion of the optical path 30 between the two VRMs 21a and 21b.

[0039] In the modified version shown in Figure 3b, the processing head 100 has a transmissive optical element, i.e., a fiber end cap 110 for a transmission fiber 111 connected to the laser light source 120 of the laser processing apparatus 10, a collimating lens 105a, and a focusing lens 105b, which are fixed and immovable. Furthermore, a fixed and immovable deflection mirror 112 and protective glass 109 are provided. In this modified version, the two VRMs 21a and 21b are positioned between the collimating lens 105a and the focusing lens 105b in the free-processing laser beam 104. For optical imaging of the optical system 103, in this modified version of the processing head 100, both the ratio of the lens focal lengths, i.e., the ratio of the focal length of the focusing lens 105b to the focal length of the collimating lens 105a, and the length of the portion of the optical path 30 between the two VRMs 21a and 21b are deterministic. The basic magnification setting is constructed using the focal length ratio of lenses 105a and 105b. The focal point 104a of the processing laser beam 104 is shown in Figure 3b, for example, located in the region of the exit aperture 108.

[0040] In the examples of Figures 3a and 3b, the VRMs 21a and 21b can vary in minimum radius of curvature R up to ±3m. The length AL of the portion of the optical path 30 between the first deformable mirror 21a and the second deformable mirror 21b is at least 300mm, as shown by the dashed arrow in Figure 3b. By appropriately presetting the length AL within a range of at least 300mm, the magnification and the position of the focal point 104a, for example, on axis A, can be advantageously changed. The position of the focal point 104a is also called the focal position. For example, in the case of laser beam cutting, a magnification range greater than about 1.7x, for example from about 1.7x to about 3.8x, and an adjustment range of the focal position of about 40mm are configured.

[0041] In the examples of Figures 3a and 3b, the collimating lens 105a has a focal length of 100 mm and the focusing lens 105b has a focal length of 250 mm, resulting in a basic magnification setting of 2.5. For a length of 900 mm AL, the magnification adjustment range is 1.8x to 3.7x, and the average adjustment range of the focal position is -20 mm upward from the exit opening 108 and +60 mm downward from the exit opening 108. The region 116 in which the magnification and the position of the focal point 104a can be adjusted is shown in Figure 6 in this example. Region 116 is the parameter region. Slightly different focal positions can be achieved depending on the magnification setting. In this example, the adjustment range of the focal position is sufficiently large for each magnification from 1.8x to 3.7x, and as a result, the workpiece 12 formed as sheet metal with a thickness of less than 200 mm can be easily cut.

[0042] The total length of the optical path 30 from interface 107 to exit aperture 108, also called the laser path length, is 1500 mm in the examples shown in Figures 3a and 3b. Despite this considerably long total length, the extension D of the housing 102 of the processing head 100, parallel to the central axis A of the exit aperture 108, is less than 400 mm. Therefore, the ratio of the laser path length to the extension D is a favorable 3.75. The angles α1 and α2 are 7.5° to 10.5°, respectively. The ratio of the extension D to the length AL is approximately 0.44.

[0043] The laser processing head 100 in Figures 3a and 3b can optionally be equipped with different pairs of lenses 105a and 105b, i.e., different basic magnification settings. The parameter range in which the magnification and the position of the focal point 104a can be adjusted depends on the lens combination, i.e., the basic magnification setting. A modified basic magnification setting, i.e., a modified pair of lenses 105a and 105b, and therefore a modified ratio of the focal length of lens 105b to the focal length of lens 105a, modifies this range. Alternative regions 116a, 116b, and 116c in which the magnification and the position of the focal point 104a can be adjusted are shown in Figure 7. Region 116a (solid line) is for a basic magnification setting of 1.5, region 116b (dashed line) is for a basic magnification setting of 2.6, and region 116c (dotted line) is for a basic magnification setting of 3.6. The larger the basic magnification setting, the wider the range in which the magnification and the position of the focal point 104a can be adjusted.

[0044] The planar deflection mirror 112 functions solely to guide the processing laser beam 104 to the exit aperture 108 and does not affect the beam shaping of the processing laser beam 104.

[0045] As a further example, a laser processing head 200 is shown in Figure 4. In this example, two fixed planar deflection mirrors 23a and 23b are positioned one-to-one in the propagation direction of the processing laser beam 104, and are located between the first mirror 21a and the second mirror 21b. As a result, the optical path 30 between the first mirror 21a and the second mirror 21b is divided into optical subpaths 230a, 230b, and 230c. Dividing the optical path 30 into such subpaths means that the laser processing head 200 can be compactly constructed in an extension perpendicular to the extension D, and there is no need to shorten the portion of the optical path 30 through which the processing laser beam 104 passes between the VRMs 21a and 21b. The planar deflection mirrors 23a and 23b only change the propagation direction of the processing laser beam 104. The beam profile, beam shape, and beam divergence of the processing laser beam 104 remain unchanged when reflected by the deflection mirrors 23a and 23b. In the design of the laser processing head 200, the extension section D is less than 500 mm. Therefore, the ratio of the laser path length to the extension section D is approximately 3. Furthermore, the ratio of the extension section D to the length AL is 0.55.

[0046] A laser processing head 300 is shown in Figure 5 as a further example. Unlike the previously mentioned example, the interface 107 is located in the lateral region of the housing 102 adjacent to the exit opening 108. In this example, the optical path 30 between the first mirror 21a and the second mirror 21b is divided into optical subpaths 330a, 330b, and 330c. This is achieved by placing two planar deflection mirrors 23a and 23b one after the other in the optical path 30 between the VRMs 21a and 21b. This results in a compact design for the processing head 300. It is noteworthy that a portion of the optical path 30 of the processing laser beam 104 intersects. An advantage of this example is that the planar mirror 112 can be transparent to observation light and easily accessible for processing monitoring. An optional processing monitoring unit 17, shown as a dashed line in Figure 5, consists of, for example, a camera and / or photodiode, and may be provided at a further interface 106 of the housing 102. The optical path 30 between interface 107 and exit aperture 108 is 1700 mm in this example. Even with this design of the machining head 300, the extension D of the housing 102, i.e., the extension D without the machining monitoring unit 17, is less than 500 mm. Therefore, the ratio of the total length to the extension D parallel to the central axis A of the exit aperture 108 is 3.4. Here again, the ratio of the extension D to the length AL is approximately 0.55.

[0047] The imaging characteristics of machining heads 200 and 300 in Figures 4 and 5 correspond to the imaging characteristics of machining head 100 in Figures 3a and 3b.

[0048] Finally, it should be noted that in the examples of machining heads 100-300 in Figures 3a-5, the adaptive VRMs 21a and 21b are used instead of lenses that can be displaced parallel to the machining laser beam 104, offering the further advantage that the focal position and magnification of the machining laser beam 104 can be changed much more quickly. By changing the curvature, i.e., radius of curvature, of the VRM, the focal position and magnification can be changed much more quickly than when a transmissive optical element such as a lens is displaced parallel to the machining laser beam 104. Changing the full stroke of the VRM, i.e., the radius of curvature, from -3m to +3m, takes less than 30ms. This means that a change in magnification from 1.8 to 3.7 can be performed within 30ms. The focal position can also be changed from -20mm to +60mm within 30ms. On the other hand, a machining head with a lens that can be displaced parallel to the machining laser beam takes up to 8 to 10 times longer to make such changes.

[0049] In further modifications of the above example, an additional VRM may be provided between VRMs 21a and 21b as an additional fixed variable mirror. In such modifications involving more than two VRMs, the portion of the optical path 30 between VRMs 21a and 21b may be further shortened, allowing for greater compactness of the machining head. In these modifications, the portion of the optical path 30 between adjacent VRMs may have a length in the range of 150 mm to 450 mm, preferably 280 mm to 350 mm, in each case. [Explanation of symbols]

[0050] 1. Laser processing head 2. Transmission fiber 3a, 3b Lens displacement mechanism 4 laser beams 5a Collimating Lens 5b Focus Lens 7 Processing position 8 outlet opening 9. Protective Glass 10 Laser processing equipment 12 Workpiece 17 Processing Monitoring Unit 21a Deformable mirror, VRM 21b Deformable mirror, VRM 25 Surface 26 membrane 27 Fluid space 28 Actuators 29 Control device 30 light path 100 laser processing heads 102 Housing 103 Optical system 104 Processing laser beam 104a focus 105a Collimating Lens 105b Focus Lens 107 Interfaces 108 Exit opening 109 Protective Glass 110 Fiber End Cap 111 transmission fiber 112 Polarizing mirror 116 areas 116a area 116b area 116c area 120 Laser light sources 200 laser processing heads 230a Subpath 230b Subpath 230c Subpath 300 laser processing heads 330a Subpath 330b Subpath 330c Subpath

Claims

1. A laser processing apparatus for laser processing a workpiece (12), particularly for laser cutting, comprising laser processing heads (100, 200, 300), wherein the laser processing heads are A housing (102) having an interface (107) for connecting a laser light source for a processing laser beam (104) and an exit opening (108) for the processing laser beam (104), and An optical system (103) for shaping the processing laser beam and guiding the processing laser beam onto an optical path (30) having the entire length between the interface (107) and the exit aperture (108). Includes, Here, The housing (102) surrounds the optical system (103) and has a spatially extended portion (D) parallel to the central axis (A) of the exit opening (108), and also, The optical system (103) includes a first fixed deformable mirror (21a) and a second fixed deformable mirror (21b), which are arranged to deflect the processing laser beam at angles (α1, α2), respectively. The ratio of the total length of the optical path (30) between the exit opening (108) and the interface (107) for connecting the laser light source to the spatial extension (D) of the housing (102) parallel to the central axis (A) of the exit opening (108) is in the range of 2 to 4.

5. Characterized by, Laser processing equipment.

2. The total length of the optical path (30) is in the range of 1000 mm to 2500 mm, preferably 1400 mm to 1900 mm, and / or The spatial expansion portion (D) of the housing (102) parallel to the central axis (A) of the outlet opening (108) is in the range of 300 mm to 700 mm, preferably 400 mm to 600 mm, and / or The radius of curvature of the first mirror (21a) and / or the radius of curvature of the second mirror (21b) is in the range of -1.5m to +1.5m, and / or The portion of the optical path (30) between the first deformable mirror and the second deformable mirror has a length (AL) of at least 300 mm, preferably in the range of 700 mm to 1100 mm, and / or The angles (α1, α2) are acute angles in the range of 5.5° to 12.5°. The apparatus according to claim 1.

3. The ratio of the portion of the optical path (30) between the first and second deformable mirrors (21a, 21b) in the spatial extension portion (D) of the housing (102) parallel to the central axis (A) of the exit opening (108) to the length (AL) is in the range of 0.33 to 0.

9. The apparatus according to either claim 1 or 2.

4. The first and second deformable mirrors (21a, 21b), in particular the actuators (28) of the first and second deformable mirrors, are designed to be controllable individually and / or in a manner coordinated with each other, to adjust the radius of curvature and / or The first and / or second deformable mirrors (21a, 21b) are deformable to change at least one element selected from the divergence of the processing laser beam and the diameter of the processing laser beam. The apparatus according to any one of claims 1 to 3.

5. At least one element selected from the optical system (103) and the control device (29) for the laser processing head is designed to change the focal position of the processing laser beam and the magnification of the optical system (103) by adjusting at least one of the radii of curvature of the first deformable mirror and the second deformable mirror, in particular by adjusting only at least one of the radii of curvature of the first deformable mirror and the second deformable mirror, and / or At least one element selected from the optical system (103) and the control device (29) is such that the change in curvature of the first and / or second mirrors (21a, 21b) is at least 2.3 (m × s) －１ Designed to happen in The apparatus according to any one of claims 1 to 4.

6. At least one element selected from the optical system (103) and the control device (29) is designed such that the focal position of the processing laser beam at the processing position (7) is adjustable in the range of -90 mm to +110 mm, preferably -40 mm to +40 mm, and / or the magnification of the optical system is adjustable in the range of 1.4 to 4.8, preferably 1.7 to 3.

8. The apparatus according to any one of claims 1 to 5.

7. The optical system (103) includes only optical elements fixed in the propagation direction of the processing laser beam, and / or The optical system (103) includes one or more further optical elements selected from mirrors, adaptive mirrors, deflection mirrors (112), lenses (105a, 105b), and fiber end caps, each of which is fixed and / or At least one optical element, selected from at least one fixed planar mirror, at least one fixed adaptive mirror, and at least one further fixed deformable mirror, is provided between the first and second mirrors (21a, 21b), and / or The portion of the optical path (30) between the at least one further deformable mirror and at least one adjacent mirror selected from the first deformable mirror, the second deformable mirror, and the further deformable mirror has a length in the range of 150 mm to 450 mm in each case. The apparatus according to any one of claims 1 to 6.

8. By providing at least one fixed optical element between the first and second mirrors (21a, 21b), the optical path (30) between the first and second mirrors is divided into optical subpaths (230a, 230b, 230c, 330a, 330b, 330c). The apparatus according to any one of claims 1 to 7.

9. The laser light source (120) for the processing laser beam is connected to the interface (107) and / or The housing (102) has a further interface (106) for connecting further components, in particular a camera for monitoring the processing and / or a light source for illumination. The apparatus according to any one of claims 1 to 8.

10. A laser processing method for laser processing a workpiece (12) using a laser processing apparatus described in any one of claims 1 to 9, particularly for laser cutting, A step of generating a processing laser beam (104) using a laser light source (120) connected to the interface (107) of the housing (102) of the laser processing head (100, 200, 300), The steps include shaping the processing laser beam (104), and guiding the processing laser beam along the optical path (30) having the entire length between the interface (107) and the exit opening (108) of the laser processing head using the optical system (103), A step of adjusting at least one of the radii of curvature of the first fixed deformable mirror (21a) and the second fixed deformable mirror (21b), The steps include deflecting the processing laser beam (104) at angles (α1, α2) in the first deformable mirror and the second deformable mirror, respectively, The process involves processing the workpiece (12) using the processing laser beam (104), A laser processing method, including the following.

11. The ratio of the total length of the optical path to the spatial extension portion (D) of the housing (102) parallel to the central axis (A) of the exit opening (108) is in the range of 2 to 4.5, preferably 2.5 to 4, and / or The portion of the optical path (30) between the first deformable mirror and the second deformable mirror has a length (AL) of at least 300 mm, preferably in the range of 700 mm to 1100 mm, and / or Acute angles in the range of 5.5° to 12.5°, preferably 7.5° to 10.5°, are selected or preset as the angles (α1, α2). The laser processing method according to claim 10.

12. The first and second mirrors (21a, 21b), in particular the actuators (28) of the first and second mirrors, are controlled individually and / or in conjunction with each other, in particular in conjunction with the control device (29), to adjust the radius of curvature and / or, The first deformable mirror and / or the second deformable mirror are deformed to change at least one element selected from the divergence of the processing laser beam and the diameter of the processing laser beam. The laser processing method according to claim 10 or 11.

13. By adjusting at least one of the radii of curvature of the first and second deformable mirrors (21a, 21b), in particular by adjusting only at least one of the radii of curvature of the first and second deformable mirrors, the focal position of the processing laser beam (104) and the magnification of the optical system (103) are changed, and / or The change in curvature of each of the first and / or second mirrors (21a, 21b) is at least 2.3 (m × s) －１ It happens, The laser processing method according to any one of claims 10 to 12.

14. The focal position of the processing laser beam (104) is adjusted to a range of -90 mm to +110 mm, preferably -40 mm to +40 mm, and / or the magnification of the optical system (103) is adjusted to a range of 1.4 to 4.8, preferably 1.7 to 3.

8. The laser processing method according to any one of claims 10 to 13.

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