Laser machining device for laser machining a workpiece and method for laser machining a workpiece

Abstract

To provide a machining apparatus for laser-machining a workpiece to facilitate good surface finishing of the workpiece.SOLUTION: A machining apparatus for laser-machining, in particular laser-cutting, a workpiece is provided, having a device for generating a machining laser beam for rough-machining the workpiece, in particular for producing a cut having a cutting edge in the workpiece, and a device for dividing the machining laser beam into at least two energy intensity ranges, wherein a first energy intensity range for rough-machining the workpiece has a greater time-integrated radiated energy than at least one second energy intensity range for at least partially fine-machining the cutting edge.SELECTED DRAWING: Figure 1a

Description

[Technical Field]

[0001] The present invention relates to a machining device for laser processing a workpiece, to the use of a machining device for laser processing a workpiece, and to a method for laser processing a workpiece. [Background technology]

[0002] Laser processing devices are used in laser processing of workpieces, particularly in methods of thermally separating materials by laser irradiation, such as laser cutting. A laser processing head is often used to guide the machining laser beam onto the workpiece, e.g., the sheet being processed. The main requirement when processing a workpiece is to improve the quality of the processed workpiece. Laser cutting typically uses an auxiliary gas or cutting gas, which can be active or inert.

[0003] For example, in a flatbed milling system, the workpiece is treated with a laser beam and a gas jet that acts as the milling gas. The machining head is thus configured as a milling head and directs the two beams in an optimal way onto the workpiece.

[0004] When laser cutting with an active cutting gas such as oxygen, for example, the workpiece metal material is heated to its ignition temperature by the laser beam before being combusted and vaporized. The reaction of the oxygen with the workpiece material generates additional heat that supports the cutting process. The low-viscosity molten material can be removed from the cutting edge or cutting gap by the shear force of the gas. When cutting with an inert gas such as nitrogen or argon, the workpiece material is only melted by the laser output and can be blown out of the cutting gap by the kinetic energy of the gas flow.

[0005] Undesirable structures on the generated surface of a workpiece may occur during laser processing of the workpiece. For example, undesirable surface irregularities may be generated in the cutting gap and / or cutting edge during laser cutting. These may result from high energy input during rough processing, e.g., cutting with a laser beam. One type of surface irregularity may result from the periodically changing melting of the material due to the laser beam and gas flow, resulting in undesirable irregular surface profiles, i.e., so-called grooves. Another type of surface irregularity results from the fact that a melt film may form at least several millimeters deep in the cutting gap that it covers, for example, due to surface irregularities previously created by the cutting process. In addition, undesirable shapes or cutting edges with sharp edges may occur during laser cutting. These are not only difficult to address during further processing of the workpiece, but may also lead to edge alignment during painting and impair the corrosion resistance of the workpiece. The same applies to other laser processing processes. Therefore, there is a need for a method and apparatus for favorably affecting the surface finish of machined workpieces, particularly the tactility and machinability of workpieces machined using a laser beam, as well as the visual appearance of visible parts. Patent Document 1 discloses a method and device for laser etching. Patent Document 2 relates to a laser-based road surface milling device, which includes a laser device, a beam splitting unit, a first output unit, a second output unit, and a milling and translation stage. Patent Document 3 describes an apparatus for shaping a laser beam, which includes a symmetrization means capable of interacting with the laser beam, shaping at least two sections or partial beams of the laser beam, which differ in transverse direction after the interaction, so that they are spatially coherent with each other at a point or region, and a superposition means for superposing the at least two sections or partial beams on each other, the superposition means being disposed in the beam path of the laser beam after the symmetrization means. According to Patent Document 4, the beam parameter product and / or numerical aperture of a laser beam are adjusted using a step-clad optical fiber having a central core, a first cladding, an annular core, and a second cladding. According to Patent Document 5, a laser beam generated by a laser oscillator and guided to a machining head via a transmitter is split into multiple beams by a planar reflecting mirror. The laser beams thus split are reflected by another reflecting mirror having a single parabolic surface and focused to a focal point. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Chinese Patent Application Publication No. 106271046 [Patent Document 2] Chinese Patent Application Publication No. 108620746 [Patent Document 3] German Patent Application Publication No. 102008037042 [Patent Document 4] U.S. Patent Application Publication No. 2017 / 293084 [Patent Document 5] European Patent Application Publication No. 0882540 Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to provide a machining apparatus and method for laser machining a workpiece that facilitates a good surface finish on the workpiece. [Means for solving the problem]

[0008] This is achieved by a machining device for laser processing a workpiece according to claim 1, a use of the machining device according to claim 7 and a method for laser processing a workpiece according to claim 8.

[0009] In one embodiment of the present invention, there is provided a machining apparatus for laser cutting a workpiece, the machining apparatus comprising: a device for generating a machining laser beam for rough machining the workpiece and for creating a cut with a cutting edge in the workpiece; and a device for dividing the machining laser beam into at least two energy intensity ranges, wherein a first energy intensity range for rough machining of the workpiece has a time-integrated irradiation energy greater than at least one second energy intensity range for at least partially fine machining the cutting edge, wherein the first energy intensity range is a core region of the machining laser beam and the at least one second energy intensity range is at least one edge region of the machining laser beam, wherein the first energy intensity range and the at least one second energy intensity range are concentrically arranged, and the energy intensity ranges are adapted for rough machining and fine machining by the device for dividing the machining laser beam; the machining apparatus comprises a control unit, wherein at least one element selected from the device for dividing the machining laser beam and the device for generating the machining laser beam is connected to the control unit via a wired or wireless data transmission method and is controllable by the control unit.

[0010] The machining device enables the targeted use of different energy intensity ranges of the machining laser beam for different purposes, particularly rough machining and fine machining. The different energy intensity ranges can be accommodated for each application by a device that splits the machining laser beam. During rough machining, the workpiece can be machined using a first energy intensity range. To at least partially fine-machine the cutting edge, the workpiece can be machined using a second energy intensity range. The first energy intensity range thus has a higher time-integrated irradiance energy than the second energy intensity range. Thus, the cutting edge generated during rough machining using the first energy intensity range can be processed using the second energy intensity range, thus using a lower time-integrated irradiance energy than during rough machining. For example, the region of the machining laser beam that includes a lower time-integrated irradiance energy and is therefore not used for rough machining, such as the edge region of the machining laser beam, is used for fine machining. As a result, the surface structure of the cutting edge can be refined and processed. For example, the cutting edge generated during rough machining can be at least partially rounded and / or chamfered during fine machining. Furthermore, sharp-edged protrusions or corners of the cutting edge can be smoothed, which results in a refinement of the generated surface. Additional post-processing of the generated surface, especially of the cutting edge, can be omitted. Therefore, the machining device of the embodiment allows for a significant increase in efficiency and cost reduction when machining workpieces. Furthermore, the finished workpiece becomes easier to handle during further processing. In particular, edge alignment can be avoided when painting. Furthermore, refinement of the generated surface can promote the corrosion resistance of the workpiece. The tactility, machinability, quality, and visual appearance of workpieces machined using a laser beam are thereby optimized.

[0011] The fine machining is preferably carried out simultaneously with the rough machining. The fine machining can therefore be carried out without wasting time. This means that the simultaneous fine machining can improve the cutting quality of the machined cutting edge at the same time that the rough machining is being carried out. In the prior art, this cutting quality was only possible by time-consuming remachining of the cutting edge after the rough machining.

[0012] The device for generating a machining laser beam may include a machining laser source having multiple laser source modules, the laser source modules including at least one first laser source module and at least one additional laser source module for generating the energy intensity ranges of the machining laser beam. The device for splitting the machining laser beam may include a laser beam transport fiber having a first fiber section that is a fiber core and at least one additional fiber section in the form of a fiber jacket ring. The at least one first laser source module may be designed to generate the first energy intensity range of the machining laser beam and may be coupled to the first fiber section of the laser beam transport fiber in a laser photoconductive manner. The at least one additional laser source module may be designed to generate one of the second energy intensity ranges of the machining laser beam and may be coupled to each of the additional fiber sections assigned thereto in a laser photoconductive manner. In this way, the machining laser source module can generate several regions of the machining laser beam with different energy intensities and different time-integrated irradiation energies, which are then directed in a targeted manner by the respective assigned fiber regions to the machining region of the workpiece, e.g., the cutting edge. In particular, different energy intensity ranges of the machining laser beam can be simultaneously guided to the workpiece. A first fiber region can guide a first energy intensity range of the laser beam onto the workpiece, which is used for rough machining. At least one additional fiber region can guide one or more additional energy intensity ranges of the laser beam onto the workpiece, which have a lower time-integrated irradiation energy than the rough machining and are used for fine machining. Furthermore, the machining laser source and / or fiber region modules can be designed and / or used in a variable and / or targeted manner. In this way, rough machining and fine machining can be performed flexibly and as needed.This is possible, for example, by appropriate selection of the arrangement, number and / or width of the fiber sections, the wavelength / frequency of the light generated in the modules, and / or by independent control of the energy in each module and / or fiber section.

[0013] Fine machining of the cutting edge can also be performed after rough machining (or cutting), for example in the edge region of the cutting edge, where simultaneous machining is not possible or efficient due to the cutting geometry.

[0014] In the machining apparatus, the device for generating a machining laser beam may include a machining laser source and, optionally, a laser beam transport fiber, and the device for splitting the machining laser beam may have an optical element for shaping the machining laser beam. In this embodiment, multiple energy intensity ranges of the machining laser beam with different time-integrated irradiation energies may be generated by beam shaping, which are directed to the machining area of ​​the workpiece in a targeted manner. For example, the machining laser beam may be generated with a desired intensity distribution and / or spatial structure at least perpendicular to its propagation direction, and may be designed to be suitable for rough machining and / or fine machining.

[0015] The beam shaping element may be, for example, an optical element that provides static and / or dynamic beam shaping. A static beam former, e.g., a beam shaping lens, may be provided for static beam shaping. For static and / or dynamic beam shaping, for example, one or more tilting mirrors that are adjustable using one or more actuators (e.g., for tip / tilt piezo scanners or galvanometer scanners) may be used. Actuator-deformable surfaces, e.g., adaptive or deformable mirrors, may also be used for beam shaping of the laser beam. Dynamic beam shaping may be performed using such mirrors if the surface areas of such mirrors can be adjusted quickly and independently of one another, e.g., at frequencies exceeding 100 Hz. Dynamic beam shaping may be performed, in particular, as high-frequency beam shaping, e.g., by focal oscillation. Alternatively or additionally, the beam shaping element may be used to change the focal length of the optics of the machining device and / or adjust the focal position of the machining laser beam.

[0016] In the machining device of the embodiment, the first energy intensity range is a core region of the machining laser beam. Alternatively or additionally, the at least one second energy intensity range is at least one edge region of the machining laser beam. Furthermore, the first energy intensity range and the at least one second energy intensity range are arranged concentrically. By these measures, for example, rough machining of a workpiece using the core region of the laser beam and simultaneous fine machining using at least one edge region are possible.

[0017] In an embodiment of the machining apparatus, the device for splitting the machining laser beam can be designed to adjust or select at least two of the energy intensity ranges independently of each other. In this way, the rough machining and / or fine machining of the workpiece can be designed to be highly variable.

[0018] Furthermore, the device for splitting the machining laser beam can be designed to adjust or select the time-integrated irradiance energy of at least one second energy intensity range with increasing distance from the first energy intensity range. The at least one second energy intensity range of the laser beam can be, for example, one or more edge regions of the laser beam that are concentric with the core region. The distribution of the time-integrated irradiance energy of the machining laser beam can thus be adjusted perpendicular to its propagation direction, particularly for micromachining of the workpiece.

[0019] In embodiments, the device for splitting the machining laser beam can be designed to adjust or select at least one element from the following: the power of one or more of the machining laser source or laser source modules, the intensity distribution of the machining laser beam, particularly the intensity distribution perpendicular to the propagation direction of the machining laser beam, one or more frequencies of the machining laser beam and / or at least one of the energy intensity ranges of the machining laser beam, the spatial structure of the machining laser beam, particularly the width and / or diameter of the machining laser beam, the spatial structure and / or arrangement of the first energy intensity range and / or at least one second energy intensity range, the feed rate of the machining laser beam, the focal diameter of the machining laser beam and / or of at least one energy intensity range, the focal position of the machining laser beam and / or of at least one energy intensity range, and the focusing of the machining laser beam and / or of at least one energy intensity range. These modifications of the device for splitting the machining laser beam facilitate highly variable design of rough and / or fine machining of the workpiece, respectively. For example, the energy input into the workpiece material can be controlled by the relative velocity of the machining laser beam to the workpiece, which can be achieved by controlled movement of the machining laser beam, for example, by high frequency beam oscillation.

[0020] In embodiments, the device for splitting the machining laser beam can be designed to modify the shape of the cutting edge, in particular to round and / or chamfer the cutting edge, in this way, desired tactility, further machinability, quality and optical appearance of the workpiece machined with the laser beam and the cutting edge produced thereby can be obtained.

[0021] In an embodiment of the machining apparatus, a device for guiding a machining gas, in particular a cutting gas, onto the workpiece may be provided. Alternatively or additionally, a device for guiding a machining gas onto the workpiece may be provided, which has a nozzle-shaped outlet opening for the machining gas, which has a diameter of 0.5 to 30 mm, preferably 0.7 to 1 mm, and which is adjustable in distance from the workpiece, in particular to the cutting edge, in a range of 0 to 3 mm, preferably 0.1 to 0.3 mm.

[0022] By appropriate selection and control of the device for guiding the machining gas to the workpiece, the molten material can be moved or removed by the gas flow in a targeted manner from the cutting edge not only during rough machining but also during fine machining, thus optimizing the shape of the cutting edge. Using a device for guiding the machining gas with a nozzle-shaped outlet opening, diameter, and distance from the workpiece, rough machining and fine machining can be performed simultaneously. This embodiment allows a pressure cushion to be generated during simultaneous rough machining and fine machining on the workpiece using the machining gas or cutting gas, and the pressure pad appropriately moves or displaces the molten material both during rough machining and fine machining of the workpiece. The machining gas, e.g., cutting gas, used for rough machining can also be used for fine machining.

[0023] The invention further relates to the use of a machining device according to any one of the preceding embodiments for at least partially micro-machining a cutting edge of a workpiece.

[0024] Furthermore, the present invention relates to a method for laser machining a workpiece, in particular using a machining device according to any one of the preceding embodiments, comprising generating a machining laser beam for rough machining the workpiece and for creating a cut in the workpiece with a cutting edge, generating at least two energy intensity ranges of the machining laser beam, dividing the machining laser beam into the at least two energy intensity ranges, wherein a first energy intensity range for rough machining the workpiece has a greater time-integrated irradiation energy than at least one second energy intensity range for at least partially fine machining the cutting edge, wherein the method includes generating one energy intensity range as a core region of the machining laser beam and generating at least one second energy intensity range as at least one edge region of the machining laser beam, wherein the first energy intensity range and the at least one second energy intensity range are arranged concentrically, wherein the energy intensity ranges are adapted for rough machining and fine machining by a device for splitting the machining laser beam; and irradiating a workpiece with the machining laser beam, rough machining the workpiece with the first energy intensity range and at least partially fine machining a cutting edge of the workpiece with the at least one second energy intensity range.

[0025] In the method of the embodiment, the fine machining is preferably performed simultaneously with the rough machining, which allows, for example, the rough machining of the workpiece using a high time-integrated irradiation energy in a core region of the laser beam and the simultaneous fine machining of the cutting edge using a low time-integrated irradiation energy in at least one edge region of the laser beam.

[0026] As already mentioned, the fine machining of the cutting edge can also be carried out after the rough machining (or cutting) for example in the edge region of the cutting edge when simultaneous machining is not possible or efficient due to the cutting geometry. For example, the fine machining can also be carried out on the underside of the workpiece during remachining, i.e. after rough machining.

[0027] According to a further embodiment of the method, the energy intensity range of the machining laser beam can be generated using a plurality of laser source modules, where a first energy intensity range is generated by at least one first laser source module and at least one second energy intensity range is generated by at least one further laser source module, and the energy intensity range of the machining laser beam is coupled into a laser beam transport fiber comprising a first fiber region that is a fiber core and at least one further fiber region that is at least one fiber jacket ring. Thus, the first energy intensity range of the machining laser beam can be coupled into the first fiber region, and each of the second energy intensity ranges of the machining laser beam can be coupled into a respectively assigned further fiber region.

[0028] In a further embodiment of the method, the energy intensity range of the machining laser beam can be generated by beam shaping. Beam shaping of the machining laser beam can be performed in various ways. Beam shaping can be understood to mean changing the beam parameter product of the laser beam and / or changing the mixture of electromagnetic laser modes and / or changing the transverse distribution of the power and / or intensity of the laser beam. There is static beam shaping, in which the beam parameter product is adjusted once or at several separate (separate) times. There is also dynamic beam shaping (DBS), in which the beam parameter product is changed by continuous dynamic movement of the laser beam over a certain period of time in an averaged or integrated manner. Dynamic beam shaping can be performed in particular as high-frequency beam shaping, for example as high-frequency beam oscillation or focus oscillation. In laser processing using dynamic beam shaping, the laser beam is moved across the workpiece to be machined, for example at a frequency of 100 Hz to 10 kHz, i.e., at a frequency significantly higher than the normal reaction time between the laser beam and the material. The workpiece is therefore machined using the power distribution of the machining laser beam in a time-averaged or time-integrated manner.Dynamic beam shaping allows almost any power and intensity distribution of the laser beam spot, and therefore different regions of the machining laser beam, to be generated at least perpendicular to the propagation direction of the machining laser steel.

[0029] In an embodiment, the method includes generating a first energy intensity range in a core region of the machining laser beam, generating at least one second energy intensity range in at least one edge region of the machining laser beam, and the first energy intensity range and the at least one second energy intensity range being arranged concentrically.

[0030] In the method of the embodiment, at least two of the energy intensity ranges can be adjusted or selected independently of each other, and further, the time-integrated irradiance energy of at least one second energy intensity range can be adjusted or selected to decrease with increasing distance from the first energy intensity range.

[0031] When generating at least two energy intensity ranges of the machining laser beam, at least one element for dividing the machining laser beam into the at least two energy intensity ranges can be adjusted or selected from: one or more powers of the machining laser source or laser source module; the intensity distribution of the machining laser beam, in particular the intensity distribution perpendicular to the propagation direction of the machining laser beam; one or more frequencies of the machining laser beam and / or at least one of the energy intensity ranges of the machining laser beam; the spatial structure of the machining laser beam, in particular the width and / or diameter of the machining laser beam; the spatial structure and / or arrangement of the first energy intensity range and / or at least one second energy intensity range; the feed rate of the machining laser beam; the focal diameter of the machining laser beam and / or of the at least one energy intensity range; the focal position of the machining laser beam and / or of the at least one energy intensity range; and the focusing of the machining laser beam and / or of the at least one energy intensity range. If the cutting edge is at least partially finished, the shape of the cutting edge may be modified, in particular the cutting edge may be rounded or chamfered.

[0032] In the method of the embodiment, at least one parameter selected from the power, spatial structure, and / or arrangement of at least one energy intensity range of the machining laser beam can be adjusted or selected using at least partial micro-machining of the cutting edge.

[0033] In the method of the embodiment, a machining gas, in particular a cutting gas, can be directed onto the workpiece. Furthermore, during the fine machining of the cutting edge, the machining gas can be guided onto the workpiece through a nozzle-shaped outlet opening for the machining gas, which has a diameter of 0.5 to 30 mm, preferably 0.7 to 1 mm, and is adjusted at a distance from the workpiece, in particular from the cutting edge, of 0 to 3 mm, preferably 0.1 to 0.3 mm.

[0034] The same advantages, modes of operation, and functions as those of the methods for laser processing a workpiece of the above-described embodiments may be realized using embodiments of a machining apparatus for laser processing a workpiece, particularly those having the same and / or similar features.

[0035] Further features and advantages will become apparent from the following description of embodiments, the figures and the dependent claims. [Brief explanation of the drawings]

[0036] [Figure 1a] 1 is a diagrammatic representation of a machining apparatus 100 for laser machining a workpiece as a first example according to an embodiment of the present invention; FIG. [Figure 1b] 1A-1C are schematic diagrams illustrating exemplary laser intensity distributions for a method for laser machining a workpiece with static optical elements in a machining apparatus 100. [Figure 1c] 1A-1C are schematic diagrams illustrating exemplary laser intensity distributions for a method for laser machining a workpiece with a dynamically movable optical element in a machining apparatus 100. [Figure 2a] 2 is a schematic diagram of a second example machining apparatus 200 for laser machining a workpiece according to an embodiment of the present invention. [Figure 2b] 2 is a diagram illustrating schematically elements of a machining apparatus 200 for laser machining a workpiece. [Figure 2c] 2 is a diagram illustrating schematically elements of a machining apparatus 200 for laser machining a workpiece. [Figure 2d] 2A-2C illustrate the results of a method for laser machining a workpiece using machining device 200. [Figure 2e] 2A-2C illustrate the results of a method for laser machining a workpiece using machining device 200. [Figure 2f] 2A-2C illustrate the results of a method for laser machining a workpiece using machining device 200. [Figure 2g]2A-2C illustrate variations of a machining apparatus 200 for laser machining a workpiece and the results of an associated method for laser machining a workpiece. DETAILED DESCRIPTION OF THE INVENTION

[0037] All non-mutually exclusive features of the embodiments described herein may be combined with each other. The same elements of the embodiments are given the same reference symbols in the following description. Individual or multiple elements of one embodiment may be used in another embodiment without further reference. Embodiments of the present invention will now be described in more detail using the following examples with reference to the figures, without intending to be limited thereby. The machining device according to an embodiment of the present invention will be described below by way of example, in particular with a machining head, without limiting the present invention thereto. The machining device and method according to an embodiment of the present invention can also be realized without a machining head. A machining laser beam is also synonymously referred to as a laser beam. The term "fine machining" can be expressed as "fine machining". The term "rough machining" can be synonymously referred to as "rough machining". The time-integrated irradiation energy is also referred to as irradiation energy hereinafter. The terms "adjust" or "select" include the term "change". The same applies to variations of these terms.

[0038] Furthermore, when a range of values ​​is described herein, the specification of a broader range with narrower alternative or preferred ranges is also considered to disclose ranges that may be formed by any combination of a specified lower range limit with a specified upper range limit.

[0039] The terms "time integrated" or "time averaged" mean integrated or averaged over a period of time or for a period of time. In relation to focal spot vibration, this means integrated or averaged over at least one period of vibration, and in relation to beam vibration, integrated or averaged over at least one period of vibration.

[0040] The terms "dynamic movement" of a laser beam or "dynamically moved" laser beam, and variations thereof, mean that the laser beam moves at a high frequency, e.g., 10 Hz to 15 kHz, particularly frequencies above 500 Hz. The same applies equally to "dynamically" movable, orientable, and / or adjustable elements of a machining device.

[0041] In all embodiments, the device for generating a machining laser beam can be designed to provide a continuous and / or a discontinuous, in particular a pulsed, machining laser beam. The machining apparatus, the device for splitting the machining laser beam and / or the device for generating the machining laser beam can be connected to a control unit by wired or wireless data transmission or can include such a control unit and can be controllable by means of the control unit.

[0042] 1a shows a first example of a machining apparatus 100 according to an embodiment of the invention for laser machining a workpiece 12. In this example, the machining apparatus 100 is designed with a machining head 10.

[0043] The machining apparatus 100 has a machining laser source 18 as a device 14 for generating a machining laser beam 15. As shown in the example of Fig. 1a, the machining laser source 18 can be connected to the machining head 10 via a transport fiber. Alternatively, the machining laser source 18 can be arranged directly on the machining head 10.

[0044] The machining laser beam 15 is also referred to herein as the laser beam 15. In this example, a machining laser source 18 can be used to generate the laser beam 15, which has a core region 15a and an edge region 15b. The edge region 15b is shown by a dashed line in FIG. 1a. The core region 15a of the laser beam 15 in this example corresponds to a first energy intensity range and rough-machines the machining region 13 of the workpiece 12, generating a cutting edge 20a (shown in FIGS. 1b and 1c). The machining laser source 18 provides a laser power of approximately 6 kW and generates a machining laser beam in a spectral range that includes a wavelength of 1070 nm. However, machining laser sources with a power less than 6 kW, e.g., about 1 kW, or greater than 6 kW, e.g., 10 kW or 20 kW, can also be used. Additionally, machining laser sources providing other spectral ranges can also be used.

[0045] The machining apparatus 100 also has a device 16 for splitting the machining laser beam into at least two energy intensity ranges. The device 16 for splitting the machining laser beam into at least two energy intensity ranges may be referred to as a device 16 for generating at least two energy intensity ranges of the machining laser beam.

[0046] In this example, an optical element for shaping the beam of the laser beam is provided in the machining apparatus 100 as a device 16 for splitting the machining laser beam, which is or can be arranged in the beam path of the laser beam 15. The optical element can be designed, for example, as a lens that shapes the laser beam 15 and adjusts its intensity distribution perpendicular to its propagation direction. In this case, the optical element is designed as a static beam former, with which the edge region 15b of the laser beam 15 can have a lower energy intensity than the core region 15a. Alternatively, the optical element can be provided so as to be dynamically movable, in particular at high frequencies having a frequency of more than 100 Hz, preferably more than 500 Hz, over one or more periods. For example, a lens can be provided so as to be dynamically movable in the beam path of the laser beam 15.

[0047] The device 16 for splitting the machining laser beam 15 is thus designed to split the machining laser beam into at least two energy intensity ranges 15a, 15b, where the first energy intensity range 15a for rough machining of the workpiece has a larger time-integrated irradiation energy than the at least one second energy intensity range 15b for at least partially fine machining the cutting edge 20a. For this purpose, the device 16 for splitting the machining laser beam 15 and / or the device 14 for generating the machining laser beam 15 can be connected to a control unit (not shown) via wired or wireless data transmission. The machining apparatus 100 enables targeted use of different energy intensity ranges of the machining laser beam for different purposes, in particular for rough machining and / or fine machining.

[0048] During operation of the machining device 100, a laser beam 15 is generated in a machining laser source, directed towards the machining area 13 of the workpiece 12 and guided thereover at a feed rate. If a lens is provided as a static beam former as the optical element, the laser beam 15 passes through the static beam former. If an optical element is provided as a dynamic beam shaper, this is dynamically moved over one or more periods, in particular with a frequency above 100 Hz, preferably above 500 Hz, and thus the laser beam is shaped.

[0049] FIG. 1b shows a schematic diagram of a laser intensity distribution perpendicular to the laser beam propagation direction, generated by a static beam former during laser machining of a workpiece using the machining apparatus 100. The static beam shaping divides the laser beam 15 into a core region 15a and an edge region 15b. In the core region 15a, i.e., in a first energy intensity range, the workpiece is exposed to a greater time-integrated irradiance energy than in the edge region 15b, i.e., in a second energy intensity range. In this way, a machining gap is created in the region 13a using the core region 15a, and the workpiece is separated into two sheets 20, each with a cutting edge 20a. The edge region 15b of the machining laser beam 15 is used to fine-machine the cutting edges 20a.

[0050] FIG. 1c shows a schematic diagram of a laser intensity distribution perpendicular to the laser beam propagation direction, generated by a dynamic beam former during laser machining of a workpiece using the machining apparatus 100. Dynamic beam shaping divides the laser beam 15 into a core region 15a and a star-shaped edge region 15b. Again, in the core region 15a, i.e., the first energy intensity range, the workpiece is exposed to a higher time-integrated irradiance energy than in the star-shaped edge region 15b, i.e., the second energy intensity range. In this way, a machining gap is created in the region 13a using the core region 15a, and the workpiece is separated into two sheets 20, each with a cutting edge 20a. The edge region 15b of the machining laser beam 15, which has a lower time-integrated irradiance energy, is used to fine-machine the cutting edge 20a.

[0051] In this way, the laser beam 15 can be dynamically moved such that its time-integrated intensity distribution perpendicular to the propagation direction comprises less time-integrated irradiation energy in the further or edge region 15b than in the first region 15a or core region. The further region 15b does not have to be circular, as shown in FIG. 1b. Rather, it can have many different shapes for a dynamically moving beam, which can be achieved, for example, by beam oscillation.

[0052] During operation of the machining apparatus 100, the intensity distribution of the laser beam 15 is adjusted perpendicular to the propagation direction by static and dynamic beam shaping, so that the edge region 15b has a lower time-integrated irradiation energy than the core region 15a. The irradiation energy of the core region 15a is adjusted so that laser cutting is performed and at least one cutting edge 20a is formed during machining of the workpiece. At the same time, the irradiation energy of the edge region 15b is adjusted so that the cutting edge 20a is exposed to a lower irradiation energy than during rough machining. In this way, unwanted surface irregularities of the cutting edge, such as sharp-edged protrusions formed by high irradiation energy during rough machining, can be immediately smoothed or their formation is avoided. The cutting edge can be, for example, rounded and / or chamfered, i.e., beveled. A desired waterfall profile of the cutting edge can also be generated. As a result, the cutting edge 20a is refined and processed. Additional post-processing of the generated surface can be omitted.

[0053] During operation of the machining apparatus 100, fine machining can be performed after rough machining and / or fine machining. For example, after the workpiece has been cut using the core area 15a during rough machining, the edge area 15b of the laser beam can be guided over the cutting edge 20a formed in the machining area 13. This fine machining can be performed, for example, on the underside of the workpiece during post-machining, i.e. after rough machining and / or fine machining.

[0054] In a first example, at least one movable surface reflecting the machining laser beam 15 can be provided as a dynamic beam-shaping optical element of the device 16, which is arranged and aligned in the beam path to deflect the processing beam 15. Thus, the machining laser beam 15 can be deflected, for example, by 90° within the machining apparatus and then directed toward the workpiece. The reflecting surface can be at least partially dynamically movable by at least one or more actuators, for example, piezo actuators, thereby allowing the reflecting surface to be at least partially dynamically adjusted. For example, the at least one movable surface can be dynamically adjusted as a whole by at least one actuator. Furthermore, the at least one movable surface can provide a surface unit of a laser beam guiding device, the surface shape of which, in particular its curvature, can be dynamically adjusted. As a result, not only can the machining laser beam be shaped and / or moved at least perpendicular to its propagation direction, but the divergence of the machining laser beam can also be changed and / or the focal position of the machining laser beam can be shifted parallel to its propagation direction.

[0055] In this way, the intensity distribution of the machining laser beam 15 can be adjusted in both the core region 15a and / or the edge region 15b. Alternatively or additionally, other characteristics of the laser beam 15 can be adjusted, selected, and / or set for rough machining and / or fine machining. For example, the spatial structure of the machining laser beam, in particular its beam parameter product, its width, and / or its diameter, can be adjusted for fine machining. Furthermore, the spatial arrangement of the core region and / or edge region of the machining laser beam, the focal diameter of the machining laser beam, the focal position of the machining laser beam, and / or the focusing of the machining laser beam can be appropriately adjusted or selected for fine machining.

[0056] For example, the device 16 may include a dynamically orientable plane mirror, made of, for example, coated silicon carbide (SiC), which provides a movable surface for reflecting the machining laser beam. At least one piezo actuator serves as the actuator, with which the mirror can be dynamically moved and thereby oriented. A unit consisting of a mirror and at least one actuator is also called a piezo scanner. In the case of multiple actuators, each piezo actuator can be individually controlled by a control unit (not shown). For example, this may be a piezo actuator based on modified PZT (lead zirconate titanate) ceramic with a standard driving voltage of 120 V. For laser machining, the mirror with the movable surface is tilted by the at least one piezo actuator, resulting in the deflection of the machining laser beam 15. At the same time, the surface is dynamically moved by the piezo actuator to provide a tilt angle suitable for deflection, resulting in the dynamic movement of the machining laser beam 15. In this way, the beam parameter product of the machining laser beam 15 and the intensity distribution of the laser beam spot on the workpiece 12 can be designed as desired for each method of laser machining, since the focus of the machining laser beam 15 is dynamically moved to be at least perpendicular to its propagation direction at a frequency between 10 Hz and 15 kHz, thus shaping the laser beam spot that hits the workpiece.

[0057] In a further variant (not shown) of the first example, the device 16 includes a dynamic beam shaper with two movable reflective surfaces, which are part of a galvanometer scanner. For this purpose, the galvanometer scanner may include two mirrors, each with a movable surface. These can be dynamically moved independently as actuators, for example, by individually controllable galvanometers. The galvanometer scanner is, for example, provided with two orientable mirrors, so that the machining laser beam 15 is deflected at least once by an angle greater than 90° and at least once by an angle less than 90°. During operation, the two mirrors are oriented and moved relative to each other, so that the machining laser beam 15 is deflected twice and dynamically moved simultaneously. As a result, virtually any intensity distribution of the beam spot and / or any beam parameter product of the machining laser beam 15 can be provided by dynamic beam shaping.

[0058] In another variation of the first example, the device 16 can have a segmented mirror as a reflective, dynamically movable surface, with multiple mirror segments separated from one another and positioned adjacent to one another to form a pattern. Each mirror segment, for example, has a gold coating, is reflective to the machining laser beam 15, and can be individually and dynamically oriented by a piezo actuator. Thus, the device 16 provides a segmented entire surface that reflects the machining laser beam 15, whose surface shape, particularly its curvature, can be adjusted in a highly dynamic manner. The following applications of the segmented mirror are possible: The focal length of the optical system of the machining device can be changed with the segmented mirror; the segmented mirror can be used as a zoom optical system, i.e., for adjusting the focal position of the machining laser beam, where the machining laser beam 15 is deflected by the segmented mirror with a desired, selectable beam divergence; the segmented mirror can also be used as a static beam shaping optical system. The surface of the segmented mirror assumes a suitably controllable surface curvature depending on the desired aberration. Furthermore, the segmented mirror can also be used for dynamic beam shaping. For this purpose, the surface of the segment mirror is modified at a sufficiently high frequency above 10 Hz, in particular above 100 Hz, so that the resulting focal spot on the workpiece 12 is dynamically moved at least transversely to the direction of propagation of the laser beam. The beam parameter product and / or the time-integrated intensity distribution of the machining laser beam can be modified as required by static or dynamic beam shaping.

[0059] In an additional variation of the first example, device 16 has a deformable mirror (DM, dynamic mirror) as the dynamic beam-shaping optical element, providing a movable, reflective, continuous surface. The mirror is formed by a membrane made of a deformable material, which can be dynamically deformed by actuators. For this purpose, there are individually controllable actuators, which are evenly distributed in a pattern on the underside of the membrane. The upper part of the membrane is coated with a highly reflective dielectric multilayer coating, which is suitable for laser beams with wavelengths of 1060-1090 nm and up to 120 kW. The movable, reflective, continuous surface of the deformable mirror (DM, dynamic mirror) can be manipulated in the same way as the segmented mirrors described above.

[0060] 2a-2g show a schematic representation of a second example of a machining apparatus 200 according to an embodiment of the present invention.

[0061] As shown in FIG. 2a, in this example, the device 14 for generating the machining laser beam 15 includes a machining laser source 18, which includes multiple laser source modules 18a, 18b, and 18c, generating the regions of the machining laser beam 15. The laser source module 18a generates the core region 15a of the laser beam 15, which is intended for rough machining. The laser source modules 18b and 18c generate the edge regions 15b and 15c of the laser beam 15, which are intended for fine machining in this case. In this example, the laser source modules 18a-18c provide laser powers in the range of approximately 0.1 kW to 20 kW and generate the machining laser beam in a spectral range, which includes, for example, a wavelength of 1070 nm. The laser source modules 18a-18c may provide different laser powers and / or different spectral ranges. For example, laser source module 18a may generate 20 kW of laser power, and laser source modules 18b, 18c may generate 0.2 kW of laser power.

[0062] Furthermore, the device 16 for splitting the machining laser beam 15 comprises a laser beam transport fiber, which has a first fiber section, in this case a fiber core 16a, and at least one further fiber section, in this case two fiber jacket rings 16b and 16c. The laser source module 18a generates the core section 15a of the machining laser beam and is laser-optically coupled to the fiber core 16a of the laser beam transport fiber. Furthermore, the laser source modules 18b and 18c generate the edge sections 15b and 15c of the laser beam 15 and are laser-optically coupled to the fiber jacket rings 16b and 16c. As shown in FIG. 2b in a longitudinal cross section of the fiber and in FIG. 2c in a cross section perpendicular to the longitudinal direction of the fiber, the fiber core 16a is arranged in the center of the laser beam transport fiber and is concentrically surrounded by the fiber jacket rings 16b and 16c. The core region 15a and edge regions 15b and 15c of the laser beam are therefore also arranged concentrically.

[0063] The device 16 for splitting the machining laser beam 15 and the device 14 for generating the machining laser beam 15 are connected in this example to a control unit (not shown) by wired or wireless data transmission, and both devices can be controlled in this way.

[0064] During operation of the machining apparatus 200, the core region 15a is provided with a higher time-integrated irradiation energy by the modules 18a-18c than the edge regions 15b and 15c. This is shown in FIG. 2d, where the time-integrated irradiation energy is designated as irradiation intensity 17. This can be achieved, for example, by appropriate selection of the power and / or frequency of each of the laser source modules 18a-18c and, therefore, the power and / or frequency of the laser beam regions 15a-15c. During laser machining, the core region 15a and the edge regions 15b and 15c are guided over the workpiece 12. Due to its higher irradiation energy, a cutting edge 20a is formed using the core region 15a of the laser beam 15 on the workpiece 12. For example, the irradiation intensity 17a of the core region 15a is adjusted so that laser cutting is performed in the machining region 13, and at least one cutting edge 20a is formed during machining of the workpiece. At the same time, as shown in FIG. 2d, the irradiation intensities 17b and 17c of the edge regions 15b and 15c are adjusted independently of the core region 15a so that the machined region 13 is exposed to lower irradiation energy than the rough machining region. In this way, undesirable surface irregularities of the cutting edge 20a, such as sharp-edged protrusions formed by high irradiation intensities in the core region 15a, are immediately smoothed or their formation is avoided in the first place. The cutting edge 20a can be, for example, rounded and / or beveled, i.e., chamfered. As a result, the surface structure of the cutting edge 20a is refined and processed. Additional post-processing of the generated surface can be omitted.

[0065] The irradiation intensity of the edge regions 15b and 15c can also be adjusted independently of the core region 15a, and the irradiation intensities 17b and 17c of the machining laser beam for the edge regions 15b and 15c can be adjusted or selected as the distance from the core region 15a increases. In this way, the machining region 13 is exposed to decreasing irradiation energy outward compared to rough machining. The cutting edge 20a can also be rounded in this manner. The irradiation intensities 17b-17c of different regions of the laser beam 15 can further be varied, with only one or two of the regions 15a-15c of the laser beam 15 being generated by the laser source modules 18a-18c.

[0066] FIG. 2e illustrates a schematic diagram of an exemplary result of the second example method using laser-cut sheets 20. FIG. 2e shows a top view of the corners of two sheets 20, separated by a laser beam 15. The core region 15a of the laser beam created a cutting gap between the sheet 20 in region 13a and the cutting edge 20a of each sheet 20. Each sheet 20 shows a mirror image of the rounded region 20c of the cutting edge 20a and the chamfered region 20b of the cutting edge 20a located above it. Regions 20b and 20c were created by the edge regions 15b and 15c of the laser beam.

[0067] 2f shows, on the left, a sheet 20 cut using the second example method, and, on the right, a sheet 21 cut according to the prior art. Rounded or chamfered areas 20c and 20b can be seen on the cut edge 20a of the sheet 20 on the left, compared to the sheet 21.

[0068] FIG. 2g shows the result of a laser beam transport fiber for splitting a machining laser beam in a machining apparatus 200 and the associated method for laser processing a workpiece. FIG. 2g shows a cross section of the modified laser beam transport fiber perpendicular to its longitudinal direction. A fiber core 16a is located in the center of the laser beam transport fiber and is concentrically surrounded by a fiber jacket ring 16b. The fiber jacket ring 16c is not shown. The core region 15a of the laser beam is transported to the fiber core 16a, while the edge region 15b of the laser beam is transported to the edge region 16b. The fiber jacket ring 16b is shown here with two different diameters, indicated by arrows 160. By changing the diameter, the laser beam 15 is given an intensity distribution, as shown in FIG. 2g below with reference to the irradiation intensity 17, where the core region 15a has an intensity 17a and the edge region 15b has an intensity 17b, but their widths are different. By varying the width of the fiber jacket ring 16b, the width of the edge region 15b of the laser beam, and therefore the width of the micromachined region, can be varied.

[0069] A device for directing a machining gas, in particular a cutting gas, towards the workpiece can be arranged in the machining apparatus 100 or 200 (not shown). For example, the machining head 10 of the machining apparatus 100 shown in FIG. 1a can have a nozzle-shaped outlet opening for the machining laser beam 15. The machining head can be designed so that the machining gas also passes through the outlet opening simultaneously with the laser beam 15. The outlet opening can have a diameter of 0.5 to 30 mm, preferably 0.7 to 1 mm, and can be adjusted at a distance of 0 to 3 mm, preferably 0.1 to 0.3 mm, from the workpiece, in particular from the cutting edge.

[0070] Through appropriate selection and control of the device for guiding the machining gas to the workpiece, the molten material can therefore be moved and / or displaced in a targeted manner by the gas flow not only during rough machining but also during fine machining. Depending on the machining process, nitrogen, oxygen, compressed air, or argon can be used as the gas. In this way, the shape of the cutting edge 20a can be further optimized during fine machining. Using a device for guiding the machining gas with a nozzle-shaped outlet opening and diameter and the distance from the workpiece described above, rough machining and fine machining can be performed simultaneously.

[0071] In one example, the distance of the outlet opening, which is 2 mm in diameter, is adjusted to a distance of 0.2 mm from the workpiece 12 during simultaneous rough machining and fine machining. In this way, a pressure cushion is created above the workpiece 12 using a machining gas or cutting gas, which moves the molten material in an appropriate manner onto the workpiece surface during both rough machining and fine machining. The machining gas is used for rough machining, for example as a cutting gas, and can also be used for fine machining and refining the workpiece surface.

[0072] In method embodiments, additional fine machining can be performed after rough machining, if necessary. Machining gas can also be directed to the workpiece 12 during fine machining, which is performed after rough machining, to generate a gas flow and pressure cushion to optimize the cutting edge 20a. In one example, the machining apparatus 100 has a gas supply (not shown) with a non-nozzle-shaped outlet opening for the machining gas for this purpose. This gas supply can be located within the machining head 10 or externally thereto. The distance between the machining gas outlet opening and the workpiece 12 can be adjusted during fine machining to be greater than specified above, in particular substantially greater than 3 mm.

[0073] In all of the examples and embodiments described, the machining device may have one or more additional transmissive optical elements (e.g., lenses) and / or reflective optical elements (e.g., deflecting mirrors), for example, to deflect the machining laser beam.

[0074] Finally, it should be noted that the description of the present invention and exemplary embodiments should not be understood as limiting with respect to a specific physical realization of the present invention. All of the features described and shown in connection with individual embodiments of the present invention may be provided in different combinations in the subject matter according to the present invention to simultaneously achieve their beneficial effects. The scope of protection of the present invention is conferred by the claims and is not limited by the features exemplified in the description or shown in the drawings.

[0075] It will be particularly apparent to those skilled in the art that the present invention may be used not only in laser processing systems, but also in other devices that include a laser. Furthermore, the components of a machining apparatus for laser processing a workpiece may be produced so that they are distributed over several physical products. [Explanation of symbols]

[0076] 10 Machining Head 12 Workpiece 13 Machining area 13a Cutting gap area 14 Device for generating a laser beam for machining 15 Machining laser beam 15a First energy intensity range (core region) of the machining laser beam 15b, 15c Second energy intensity range (edge ​​region) of the machining laser beam 16 Device for splitting a laser beam for mechanical processing 16a First fiber region (fiber core) 16b, 16c Further fiber area (fiber jacket ring) 17 Irradiation Intensity 17a~17c Irradiation intensity 18 Laser source for machining 18a First laser source module of the machining laser source 18b, 18c Further laser source modules of the machining laser source 20 Cutting Sheet 20a cutting edge 20b Chamfered area of ​​cutting edge 20c Rounded cutting edge area 21 Cutting sheet by conventional technology 100 Machining equipment 160 Arrow 200 Machining equipment

Claims

[Claim 1] A processing device for laser cutting a workpiece (12), comprising: a device (14) for generating a machining laser beam (15) for creating a cut with a cutting edge in the workpiece and for at least partially micro-machining the cutting edge (20a); a device (16) for dividing the machining laser beam (15) into at least two energy intensity ranges (15a, 15b, 15c), wherein a first energy intensity range (15a) for creating a cut with a cutting edge in the workpiece has a greater time-integrated irradiation energy than at least one second energy intensity range (15b, 15c) for at least partially micro-machining the cutting edge (20a); a control unit capable of controlling the device (14) for generating said machining laser beam (15) and the device (16) for splitting said machining laser beam (15); and The device (16) for splitting the machining laser beam for at least one of cutting and micromachining with the cutting edge: designed to adjust at least one element from the focal diameter of the machining laser beam, the focal position of the machining laser beam, the focusing of the machining laser beam, and at least one energy intensity range (15a, 15b, 15c); Processing equipment.

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