Method for machining plate-shaped or tubular workpieces

Abstract

The present invention relates to a method for machining a plate-shaped or tubular workpiece by means of a machining beam comprising a laser beam and a process gas. For machining the workpiece, the machining beam is directed at the workpiece surface. In a first machining step, the workpiece is machined with a first machining beam guided along a cutting line, whereby a cutting slit is produced in the workpiece through the thickness of the workpiece, the cutting slit extending along the cutting line in its length and being delimited in its width by two cutting edges in the workpiece. And in a second machining step, the workpiece is machined with a second machining beam, the second machining beam being guided along a reworking line or reworking area which extends parallel and offset to one of the two cutting edges, whereby a rounded area, a chamfered area or a countersunk area is produced in the workpiece in the region of the cutting edge. Here, it is important that the first machining beam comprises a process gas different from the second machining beam.

Description

Technical Field

[0001] The present invention is based on the technical field of manufacturing metal workpiece parts and relates to a method for machining plate-shaped or tubular workpieces by means of a machining beam. In this method, the workpiece is machined separately to produce a cutting gap and is also non-separately and non-jointly modified to produce a rounded area, a chamfered area or a countersunk area. Background Art

[0002] Commercially available laser cutting devices enable the automated manufacture of workpiece parts in large quantities and with high precision. Here, the workpiece part is cut off from the metal workpiece by means of a laser beam along a cutting line corresponding to the contour of the workpiece part. Additionally, holes, i.e., parts with a small diameter, can be introduced into the workpiece part to be cut off at high speed by the movement of the laser beam along a circular cutting line.

[0003] Depending on the application of the cut-off workpiece part, the workpiece part may require laborious mechanical reworking. Therefore, it can be desirable to round off sharp cutting edges or provide chamfers or countersunk heads. Holes (in which countersunk bolts should be arranged when the workpiece part is subsequently used) are usually reworked by means of a drilling machine to form a chamfer or a countersunk head for receiving the head of the countersunk bolt.

[0004] In principle, subsequent mechanical processing is very time-consuming and mostly also labor-intensive, especially often carried out manually. In addition, such reworking is cost-intensive, so that the manufacture of the workpiece part is undesirably prolonged and made expensive. This particularly applies to the cutting reworking of holes for producing chamfers or countersunk heads, which is very time-consuming. Summary of the Invention

[0005] In contrast, the object of the present invention is to extend the conventional method for machining plate-shaped or tubular workpieces by means of a machining beam in such a way that it is possible to more quickly, at lower cost and with higher quality, by means of automation, manufacture workpiece parts with rounded cutting edges, chamfers or countersunk heads on the cutting edges.

[0006] This object is achieved by a method for machining plate-shaped or tubular workpieces by means of a machining beam, which machining beam includes a laser beam and a process gas for expelling the melted workpiece material.

[0007] In the context of the present invention, the term "workpiece" denotes a plate-shaped or tubular, typically metallic, component from which at least one workpiece part (a qualified part) can be manufactured. The plate-shaped workpiece is typically planar or flat. Preferably, the workpiece comprises, or consists of, steel, especially structural steel or stainless steel, or comprises, or consists of, aluminium. For example, the workpiece comprises non-alloy structural steel, or consists of non-alloy structural steel. Preferably, the non-alloy structural steel is S235, S275, S355, S460, S185, S295, E355, E360, particularly preferably S235 as commercially available (e.g. ESB: European Steel Business Group). Particularly preferably, the material for the workpiece is chromium-nickel steel. Preferably, the workpiece has a material thickness of from 3 mm to 60 mm.

[0008] The machining beam is guided by the cutting head and exits at the cutting nozzle at the end. The laser beam typically has a rotationally symmetric beam cone that is focused and has a central beam axis (symmetry axis). The beam diameter represents the lateral extent of the beam or the physical size of the beam perpendicular to the propagation direction. When focusing, the laser beam is focused by a focusing lens or focusing mirror. The focus of the laser beam is defined by the position at which the laser beam has its smallest cross-section or smallest beam diameter. The focal length describes the distance between the principal plane of the lens (or the principal plane of the mirror) and the focus of the ideally focused parallel beam. The smaller the focal length, the more strongly the laser beam is focused and the smaller the focus diameter, and vice versa.

[0009] The cutting head is also used to guide the process gas, which typically, but not necessarily, exits from the same cutting nozzle and is preferably guided coaxially with the laser beam. The process gas typically, but not necessarily, has the form of a gas cone arriving at the workpiece.

[0010] The workpiece is supported on the workpiece support with its lower side. On the upper side of the workpiece, the workpiece has (the upper-side) workpiece surface. In the case of a plate-shaped workpiece, the workpiece surface is planar. If there is no other application, herein and furthermore, the "workpiece surface" is understood to mean the upper-side workpiece surface on which the machining beam arrives. The opposite workpiece surface is the lower side of the workpiece on which the workpiece is typically supported on a base (Unterlage).

[0011] The cutting head for guiding the laser beam and the process gas can move relative to the workpiece in a typically horizontal plane parallel to the plane of the workpiece surface and in a direction perpendicular thereto, typically vertically.

[0012] In the description of the present invention, the reference system is always stationary with respect to the workpiece, so that the cutting head is considered to be moving while the workpiece is considered to be stationary. However, locally it is not important whether the cutting head or the workpiece is moving or both are moving. It could equally well be that, instead of the moving cutting head, the workpiece is moving, or that both the cutting head and the workpiece are moving.

[0013] The energy of the laser beam depends on the specific design of the laser source and is typically given in joules (J). The power of the laser beam (i.e., the energy per unit time), typically measured in joules per second (J / s) or watts (W), describes the optical output power of a continuous wave laser (CW) or the average power of a pulsed laser. A pulsed laser is also characterized by its pulse energy, which is directly proportional to the average power of the laser and inversely proportional to the repetition rate of the laser. "Energy density" refers to the energy of the laser beam on the irradiated surface of the workpiece. The energy density is, for example, measured in J / mm 2 .

[0014] In addition to the energy density, important for the laser processing of the workpiece is also the speed of movement of the laser processing head or the laser beam, i.e., the time for which a defined surface of the workpiece is irradiated by the laser beam. Usually, for this purpose, the term "energy per unit length (Streckenenergie)" is used. This is the laser beam power absorbed by the workpiece per unit speed of the laser processing head or the laser beam, for example, measured in watts per (mm / s). If the power of the laser beam is stated in watts (W) as joules per second (J / s), the energy per unit length is then measured in J / mm.

[0015] Therefore, in laser processing, it is important the energy per unit length of the laser beam, where the energy absorbed by the workpiece is related to the energy density. The energy absorbed by the workpiece is, for a given power of the laser beam, related to the size of the beam spot on the workpiece and accordingly to the beam diameter at the location where the laser beam reaches the workpiece. The beam diameter of the laser beam on the workpiece results from the focal position, i.e., the position of the focus of the laser beam relative to the workpiece (the shortest perpendicular distance), in particular relative to the workpiece surface (the laser beam is aligned with this workpiece surface) or relative to the workpiece support. If the workpiece is located in the divergence region of the beam cone (the focus is above the workpiece surface where the laser beam reaches), the beam diameter on the workpiece can be increased by increasing the distance between the focus and the workpiece, and vice versa. Thus, the energy density of the laser beam and thereby the energy absorbed by the workpiece, which goes into the energy per unit length, can be changed purposefully by changing the beam diameter on the workpiece and by changing the focal position. The larger the beam diameter, the smaller the energy absorbed by the workpiece, and vice versa. In the case of a laser, the beam intensity outside the focus varies across the cross-section. Ideally, the power intensity is a Gaussian curve (Gauβ-Profil). In any case, the energy density is smaller towards the edges, especially outside the focus.

[0016] The energy per unit length is also related to the speed of the laser beam, i.e., the moving speed of the laser processing head or the cutting nozzle, which is also called the "feed rate". The greater this feed rate, the shorter the defined surface of the workpiece is irradiated, and vice versa. Thus, with increasing feed rate, the energy per unit length of the laser beam decreases, and vice versa. Of course, the energy density and thus the energy per unit length can also be changed by varying the power of the laser beam itself. The energy introduced into the workpiece can also be changed by changing the type and / or composition of the process gas used in the processing.

[0017] According to the present invention, a plate-shaped or tubular workpiece is machined by aligning a machining beam (i.e., a laser beam and a process gas) with the workpiece surface in a method comprising two steps. In a first machining step, the workpiece is machined with a first machining beam guided along a cutting line, whereby a cutting slit is produced in the workpiece through the thickness of the workpiece, the cutting slit extending in its length along the cutting line and being delimited in its width by two cutting edges in the workpiece. In a second machining step, the workpiece is machined with a second machining beam which is guided along a reworking line or a reworking zone extending parallel and offset to one of the two cutting edges, whereby a rounded zone, a chamfered zone or a countersunk zone is produced in the workpiece in the region of this cutting edge. For the sake of simple reference and distinction, the machining beam used in the first machining step is referred to as the "first machining beam", while the machining beam used in the second machining step is referred to as the "second machining beam". It is important here that the first machining beam comprises a process gas different from the second machining beam. The laser beam acts together with the process gas aligned with the cutting seam (Schnittfuge).

[0018] The method according to the present invention thus comprises two method steps. In the first machining step, the first machining beam is used in a separating mode, and in the second machining step, the second machining beam is used in a non-separating mode. In the cutting mode, the energy per unit length of the laser beam on the workpiece or the energy introduced into the workpiece is so great that the machining beam machines (separates) the workpiece in a cutting manner, so as to penetrate the workpiece in order to produce a cutting slit. In the non-cutting mode, the energy per unit length of the laser beam on the workpiece or the energy introduced into the workpiece is so small that the workpiece is machined in a non-cutting (non-separating) manner, so as not to penetrate the workpiece, thereby producing a rounded zone, a chamfered zone or a countersunk zone.

[0019] Preferably, the first machining beam in the first machining step and the second machining beam in the second machining step are always oriented perpendicular to the workpiece surface.

[0020] The process gas used in the laser machining serves to expel the molten workpiece material or the melt through the cutting slit. It is also necessary when producing a rounded zone, a chamfered zone or a countersunk zone that not only the laser beam but also the process gas acts on the workpiece in order to conduct the formed melt or residue out.

[0021] In the method according to the present invention, the first machining beam comprises a process gas different from the second machining beam. In the sense of the present invention, there is in particular another process gas if the process gas in the first machining beam differs from the process gas in the second machining beam in terms of the gas type used and / or composition and / or in terms of the gas pressure. By this measure, a series of important advantages can be achieved, in particular using the machining beam in the cutting and non-cutting modes for machining the workpiece.

[0022] In an advantageous configuration of the method according to the invention, the process gas of the first machining beam includes nitrogen (N2) or oxygen (O2) or a gas mixture of nitrogen (N2) and oxygen (O2) as a basic component (main component), wherein, in the latter case, the gas mixture itself constitutes the main component of the process gas. The process gas of the second machining beam includes oxygen (O2) or nitrogen (N2) or a gas mixture of nitrogen (N2) and oxygen (O2) as a basic component (main component), wherein, in the latter case, the gas mixture itself constitutes the main component of the process gas. Preferably, the process gas of the first machining beam includes oxygen or nitrogen as a basic component. Preferably, the process gas of the second machining beam includes oxygen or nitrogen as a basic component. For example, the process gas of the first machining beam includes nitrogen as a basic component, while the process gas of the second machining beam includes oxygen as a basic component.

[0023] In the sense of the present invention, "basic component" is understood to mean that the corresponding gas is more than 50%, in particular more than 75%, or even more than 90% of the components in the process gas. The process gas can in particular consist entirely of the corresponding gas that constitutes the main component. Similarly, it also applies that the main component is a gas mixture of oxygen and nitrogen.

[0024] Particularly advantageously, for machining a workpiece made of structural steel, oxygen is used as a basic component of the process gas in the second machining beam. Thereby, the formed melt can be advantageously completely oxidized in the cutting gap and can thus be easily removed from the workpiece. The process gas in the first machining beam can have oxygen or nitrogen or a gas mixture of oxygen and nitrogen as a basic component. Preferably, the process gas in the first machining beam has oxygen or nitrogen as a basic component.

[0025] When machining a workpiece made of stainless steel or aluminum, nitrogen is advantageously used as a basic component of the process gas in the second machining beam. Nitrogen is an inert gas and is cost-effectively available. The process gas in the first machining beam can have oxygen or nitrogen or a gas mixture of oxygen and nitrogen as a basic component. Preferably, the process gas in the first machining beam has nitrogen as a basic component.

[0026] Advantageously, the gas pressure of the process gas in the second machining beam is changed, in particular, based on the material thickness of the workpiece and / or the design dimensions of the rounded area, chamfered area or countersunk area, compared to the gas pressure of the process gas in the first machining beam. Particularly advantageously, the process gas of the second machining beam is loaded with a smaller gas pressure than the process gas of the first machining beam. By this measure, it is advantageously achieved that the process gas acts on the workpiece surface less concentratedly and "more softly", so that excessive material splashing (Materialspritzer) on the workpiece surface can be avoided. Preferably, the gas pressure of the process gas in the second machining beam is less than 7 bar. Thereby, on the one hand, good removal of the melt is achieved, and on the other hand, material splashing can be reliably and safely avoided. The gas pressure (tank pressure) applies in the cutting head before the process gas exits from the cutting nozzle.

[0027] Advantageously, if the process gas of the second machining beam contains oxygen as a basic component, then the process gas is loaded with a gas pressure in the range of 2 bar to 4 bar. This gas pressure is particularly advantageously combined with a cutting nozzle having a nozzle diameter of 0.8 mm - 1.4 mm. Advantageously, if the process gas of the second machining beam contains nitrogen as a basic component, then the process gas is loaded with a gas pressure in the range of 0.3 bar to 1 bar. This gas pressure is particularly advantageously combined with a cutting nozzle having a nozzle diameter of at least 2.7 mm, in particular exactly 2.7 mm.

[0028] In the method according to the invention, the machining beam is used in a separated or non-separated mode. Advantageously, the laser power of the laser beam in the second machining beam is changed, in particular, based on the material thickness of the workpiece and / or the design dimensions of the rounded area, chamfered area or countersunk area, compared to the laser power of the laser beam in the first machining beam. The larger the design dimensions of the rounded area, chamfered area or countersunk area, the typically higher the laser power. The larger the material thickness of the workpiece, the typically higher the laser power.

[0029] Preferably, the laser power of the laser beam in the second processing beam is less than the laser power of the laser beam in the first processing beam, wherein, particularly preferably, the laser power of the laser beam in the second processing beam is at most 4 kW, especially less than 4 kW, for example less than 3.5 kW. Advantageously, the laser power of the laser beam in the first processing beam is in the range of 1 kW to 40 kW, while in the second processing beam it is in the range of 0.5 kW to 4 kW. Thereby, the energy per unit length of the laser beam used for the processing beam can be adjusted specifically in the cutting or non-cutting mode. For example, in the second processing step, the (average) laser power is less than 3.5 kW, and / or the focal diameter of the laser beam is at least 150 μm, and / or the feed rate is at least 1 m / min. The closer the focus of the laser beam is to the workpiece, the larger the focal diameter should be selected in the second processing step. Preferably, the focal diameter is greater than 250 μm in the case of the focal position on the workpiece surface.

[0030] For example, the laser power of the laser beam is in the range of 1 kW to 40 kW in the first processing beam with a process gas containing oxygen or nitrogen as a basic component. For example, the laser power is at most 4 kW for a sheet thickness of up to 12 mm and oxygen as the process gas when structural steel is used as the material for the workpiece, and at most 10 kW for a sheet thickness greater than 12 mm. In the case of using nitrogen as the process gas, the maximum possible laser power technically available for the equipment can be used.

[0031] In an advantageous configuration of the method according to the invention, the processing beam is guided by a cutting nozzle with a nozzle diameter before reaching the workpiece surface, wherein the same nozzle diameter, in particular the same cutting nozzle, is used for the first and second processing beams. By this measure, a particularly simple method implementation can be achieved. In addition, the costs for performing the method according to the invention can be reduced.

[0032] In an advantageous configuration of the method according to the invention, in order to produce a cutting gap, the first processing beam is guided only once along the cutting line; and in order to produce a rounded area, a chamfered area or a countersunk area, the second processing beam is guided multiple times along a reprocessing line or a reprocessing area. This can effectively produce a cutting gap on the one hand and reliably form a rounded area, a chamfered area or a countersunk area on the other hand. Preferably, the laser power of the laser beam in the second processing beam is smaller in the last pass along the reprocessing line or area than in at least one previous pass along the reprocessing line or area, in particular the laser power is reduced by half. In principle, it applies that the more the cutting head or the cutting nozzle moves over the smaller the laser power required.

[0033] The energy per unit length of the laser beam on the workpiece or the energy introduced into the workpiece can be changed by varying the energy or power of the laser beam and / or by varying the feed rate of the cutting head and / or by focusing / defocusing the laser beam, i.e., by changing the beam diameter on the workpiece surface, in particular by changing the position of the focus relative to the workpiece and / or by changing the process gas used during machining.

[0034] Preferably, the change in the energy per unit length of the laser beam on the workpiece is achieved by changing the position of the focus relative to the workpiece, which is preferably caused by a change in the height of the cutting head on the workpiece surface facing the cutting head, i.e., the cutting head typically moves in a vertical direction with a movement component perpendicular to the workpiece surface.

[0035] In an advantageous configuration of the method according to the invention, the first machining beam forms a smaller beam diameter on the workpiece surface than the second machining beam. Advantageously, the cutting nozzle has a smaller spacing from the workpiece surface in the first machining step than in the second machining step. Preferably, the beam diameter of the first machining beam on the workpiece surface is less than 50%, less than 40%, less than 30%, less than 20%, less than 10% or even less than 1% of the beam diameter of the second machining beam on the workpiece surface. In currently commonly used laser cutting machines, the beam diameter on the workpiece is typically 1 / 10 to 5 / 10 mm during separation machining. In order to produce a rounded area, a chamfered area or a countersunk area by the machining beam, the beam diameter on the workpiece is preferably at least 1.5 mm and, for example, in the range from 3 to 25 mm.

[0036] Preferably, the beam diameter on the workpiece is changed by varying the perpendicular spacing of the cutting nozzle from the workpiece surface. Particularly advantageously, the beam diameter on the workpiece is changed only by varying the perpendicular spacing of the cutting nozzle from the workpiece surface. Advantageously, in the first machining step, the spacing of the cutting nozzle from the workpiece surface is at most 5 mm, while in the second machining step it is at least 15 mm, in particular at least 30 mm. Advantageously, in the second machining step, the focus of the laser beam lies on the workpiece surface or above the workpiece surface. Preferably, the change in the focus position of the laser beam relative to the workpiece is achieved by changing the height of the cutting head or the cutting nozzle on the workpiece, i.e., the cutting head typically moves in a vertical direction with a movement component perpendicular to the workpiece surface.

[0037] In an advantageous configuration of the method according to the invention, the energy input per unit area and per unit time into the workpiece is greater in the first machining step than in the second machining step.

[0038] In an advantageous configuration of the method according to the invention, by means of a first machining step, a workpiece part (qualified part) is cut off from the workpiece, in the formation of a workpiece part and a remaining grid, wherein the outer contour of the workpiece part is determined by a cutting line. One of the two cutting edges is the cutting edge on the workpiece part side, and the other of the two cutting edges is the cutting edge on the remaining grid side. The cutting edge on the workpiece part side is machined by means of a second machining step. By this measure, the workpiece part (qualified part) can be provided with a rounded area, a chamfered area or a counterbored area in a particularly simple and effective manner by means of a machining beam.

[0039] Particularly advantageously, in order to form a cutting gap, the first machining beam is switched off and then switched on again at least once, in particular several times, during the guidance along the workpiece surface, whereby the cutting line forms a plurality of cutting line sections, such that a tab is arranged between two adjacent cutting line sections, and the workpiece part and the remaining grid are kept connected to each other by means of this tab. The workpiece part connected to the remaining workpiece is a still-fixed component of the workpiece, wherein this connection is rigid enough in the sense of the present invention, so that advantageously no change in the position of the partially cut-off workpiece part relative to the remaining workpiece occurs during the generation of a rounded area, a chamfered area or a counterbored area, or any possible change in position occurring here is negligibly small and does not lead to a change in the result to be considered. It is advantageous for the generation of a rounded area, a chamfered area or a counterbored area on the workpiece part that the workpiece part is connected to the remaining workpiece, i.e., there is still workpiece material on both sides of the cutting gap. In this way, on the one hand, the workpiece part is fixed in its position and cannot slide or tilt, so that the laser beam can be precisely positioned relative to the cutting edge during the generation of the rounded area, the chamfered area or the counterbored area. In addition, the melt formed during the generation of the rounded area, the chamfered area or the counterbored area flows into the cutting gap and can thus be removed more simply than from the upper side of the workpiece (especially in the case of using oxygen as the process gas).

[0040] Thus, in this configuration, the generation of the rounded area, chamfered area or countersunk area is carried out only in such a way that the workpiece part is connected to the remaining workpiece by one or more tabs, in particular micro joints or nano joints. In the context of the present invention, a "tab" is understood to be a connection made of workpiece material between the workpiece part and the remaining workpiece, which extends along the cutting line, wherein the tab interrupts the cutting gap. A "micro joint" is a tab along the cutting line with a smaller size, which preferably ranges from 1 / 10 to 2 mm, particularly preferably from 1 / 10 to 1 mm according to the present invention. In the usual use of the term, the micro joint has a height corresponding to the height or thickness of the workpiece (i.e., the dimension perpendicular to the workpiece surface). A "nano joint" is a micro joint whose height is reduced with respect to the thickness of the workpiece, wherein the height of the nano joint preferably amounts to at most half of the workpiece thickness according to the present invention. Micro joints and nano joints are well known to a person skilled in the art from the practice of manufacturing workpiece parts from sheets by laser machining as well as from the patent literature, so that no further discussion thereof is necessary here. Only by way of supplement, reference is made, for example, to international patent application WO 2019025327 A2 with regard to nano joints.

[0041] In order to be able to remove the workpiece part from the remaining workpiece, a closed cutting gap must be formed. In this configuration according to the present invention, a closed cutting gap is formed only after the rounded area, chamfered area or countersunk area has been generated on the cutting edge on the workpiece part side. The generation of the closed cutting gap can be achieved by means of a machining beam in a separation mode, wherein one or more tabs, in particular one or more micro joints or nano joints, are cut off, by means of which the workpiece part is still connected to the remaining workpiece. The workpiece part is hereby separated from the remaining workpiece. According to one configuration, the method according to the present invention comprises the step in which the workpiece part is cut off from the remaining workpiece by means of a machining beam in a separation mode.

[0042] The workpiece part can also be separated from the remaining workpiece without a machining beam, wherein one or more tabs are mechanically severed, by means of which the workpiece part is also connected to the remaining workpiece. This can be achieved, for example, by machining or cutting (non-machining beam) or simply by breaking the workpiece part off (Herausbrechen) from the remaining workpiece. For a person skilled in the art, the professional common measures, especially for severing micro joints or nano joints, are well known, so that it is not necessary to discuss this further here. Thus, the invention also particularly includes the case where only a section of the cutting gap is produced by means of a machining beam, wherein the workpiece part is also connected to the remaining workpiece by a single tab, in particular a micro joint or a nano joint, and wherein the tab is not separated by the machining beam but is mechanically severed in another way. According to one configuration, the method according to the invention comprises the step in which the workpiece part and the remaining workpiece are completely separated not by a machining beam but by mechanically severing one or more tabs, in particular by machining or cutting (non-machining beam) or by breaking the workpiece part off from the remaining workpiece.

[0043] In an advantageous configuration of the method according to the invention, by means of a first machining step, a hole-shaped notch is cut out of the workpiece in such a way that a waste piece and a workpiece part are formed, wherein the outer contour of the waste piece and the inner contour of the hole-shaped notch in the workpiece part are pre-given by a cutting line. One of the two cutting edges is the cutting edge on the workpiece part side, and the other of the two cutting edges is the cutting edge on the waste piece side. The cutting edge on the workpiece part side is machined by means of a second machining step. Thus, if the waste piece has been cut off from the workpiece (i.e., the waste piece has no connection made of workpiece material to the remaining workpiece), a rounded area, a chamfered area or a countersunk area is produced on the cutting edge on the workpiece part side of the workpiece part (i.e., the remaining workpiece after removal of the waste piece). By this measure, after the waste piece has been cut off from the workpiece in order to produce the workpiece part, the workpiece part (qualified part) can be provided with a rounded area, a chamfered area or a countersunk area in a particularly simple and effective manner by means of a machining beam.

[0044] For cutting the waste piece, the machining beam is guided along a circular closed cutting line in the cutting mode, thereby producing a circular closed cutting gap. Thereby, the waste piece (core piece (Butzen)) is cut off from the workpiece. However, it is also possible to divide the core piece by the machining beam. By removing the core piece from the workpiece, a hole (penetration) with a circular cross-section is produced in the workpiece. In any case, the core piece has fallen down due to its own weight, thereby producing a hole in the workpiece. Preferably, the hole is produced within the contour of the workpiece part to be cut off from the workpiece. Particularly advantageously, the hole-shaped notch has a diameter that is equal to or smaller than the workpiece thickness of the workpiece. As shown by the tests of the present invention, by the method according to the present invention, particularly small holes with chamfers or countersinks can be produced without the risk of damaging adjacent holes due to the production of the chamfers or countersinks. This is possible in the case of using oblique cutting for producing chamfers or countersinks.

[0045] The cutting gap is produced along the contour of the workpiece part or the waste piece, that is, the cutting gap always forms a contour for the workpiece part or the waste piece. Accordingly, in the sense of the present invention, the term "cutting gap" does not include the following section of the cutting gap that does not form a contour and does not extend along the contour of the workpiece part or the waste piece. For example, it often pierces into the workpiece away from the contour and first moves the machining beam away from the cutting line forming the contour by a certain distance.

[0046] In the method according to the present invention, in order to produce a rounded area, a chamfered area or a countersunk area on the workpiece, the workpiece is machined in the area of the cutting edge by means of a second machining beam. The second machining beam is guided along a reworking line or area that extends parallel and offset to one of the two cutting edges. According to one configuration, the machining beam is always guided linearly along one of the two cutting edges or parallel and offset thereto. This can produce a rounded area, a chamfered area or a countersunk area particularly quickly. According to another configuration, it is also possible to move the machining beam transversely to one of the two cutting edges (secondary movement), provided that the primary movement is guided along one of the two cutting edges or parallel and offset thereto. The secondary movement is superimposed on the primary movement. In this case, the movement of the machining beam has, in addition to the movement component along one of the two cutting edges or parallel thereto, a movement component transverse to (i.e., perpendicular to) one of the two cutting edges, such that a larger area of the workpiece is skimmed over by the machining beam. For example, the machining beam performs a meandering reciprocating movement along one of the two cutting edges or parallel and offset thereto. Here, the machining beam is guided away from the side and correspondingly guided back again several times along one of the two cutting edges or parallel and offset thereto during its movement.

[0047] Advantageously, the beam axis of the laser beam is oriented perpendicular to the planar workpiece support both in the first machining step and in the second machining step, i.e., the angle between the beam axis and the workpiece support is 90°. This brings advantages in terms of control technology. In addition, the technical implementation costs for the corresponding deflectability of the machining beam relative to the plane of the workpiece support can be saved. However, it is also possible to consider changing the beam axis when irradiating the workpiece, wherein the beam axis assumes an angle different from 90° relative to the workpiece support at least temporarily. The orientation of the laser beam can be achieved by the deflectability of the cutting head (mechanically) and / or by the deflectability of the laser beam (optically). For example, it can be advantageous to scan a larger area of the workpiece during the generation of a rounded area, a chamfered area, or a counterbored area by deflecting the laser beam.

[0048] Of course, the above configurations of the present invention can be used individually or in any combination without departing from the scope of protection of the present invention. Description of the Drawings

[0049] The present invention will now be explained in detail based on the embodiments, with reference to the drawings. The drawings show:

[0050] Figure 1 A schematic view of an exemplary laser processing device for performing the method according to the present invention;

[0051] Figures 2 - 16 An exemplary method for machining a workpiece;

[0052] Figures 17 - 18 An exemplary method for machining a workpiece;

[0053] Figures 19 - 22 An example of the non-linear movement of the laser beam along a reprocessing line;

[0054] Figures 23 - 27 Different configurations for visually showing the generation of a rounded area, a chamfered area, or a counterbored area;

[0055] Figures 28A - 28C A configuration of the method according to the present invention, in which a hole with a counterbored head or a chamfer is generated;

[0056] Figures 29A - 29D Another configuration of the method according to the present invention, in which a hole with a counterbored head or a chamfer is generated;

[0057] Figures 30A - 30B A schematic view of the cutting head at different positions for separating or non-separating machining of the workpiece;

[0058] Figure 31 A flowchart of the method according to the present invention. Detailed Description of the Invention

[0059] First, look at Figure 1 , in which a laser processing apparatus for laser-cutting a plate-shaped workpiece is intuitively shown. The laser processing apparatus generally denoted by reference numeral 1 includes a laser cutting device 2 having a cutting head 3 and a worktable 4 having a workpiece support 5 for a workpiece 9 (not shown in Figure 1 , for example, see Figures 2 to 16 ), for example, a planar sheet workpiece support 5.

[0060] The workpiece support 5 is spanned by a crossbeam 6 which is movably guided along a first axis direction (x-direction). A guide slider 7 for the cutting head 3 is mounted on the crossbeam 6, and the guide slider is movably guided on the crossbeam 6 along a second axis direction (y-direction) perpendicular to the first axis direction. The cutting head 3 can thus move parallelly and relative to, for example, a horizontal workpiece support 5 in a plane defined by two axis directions (x, y-directions). The cutting head 3 is furthermore configured to be movably mounted in height along a third axis direction (z-direction) perpendicular to the first axis direction and the second axis direction, whereby the spacing perpendicular to the workpiece support 5 or the workpiece 9 can be changed. In the case of a horizontal workpiece support 5, the z-direction corresponds to the direction of gravity.

[0061] The cutting head 3 has a cutting nozzle 13 which tapers towards the workpiece support 5 on the side facing the workpiece support 5. The cutting head 3 and the cutting nozzle 13 are used to guide a laser beam 16 together (see, for example, Figures 2 to 16 , 30A, 30B) and a process gas 25 (see Figure 27 , 30A , 30B).

[0062] The processing beam 26 for processing the workpiece 9 includes a laser beam 16 and a process gas 25 (see FIGS. 27, 30A, 30B). The process gas 25 is ejected from the cutting nozzle 13 in the form of a gas cone and is guided coaxially with the laser beam 16. Of course, the process gas 25 (i.e., the process gas beam in the form of a gas cone) is guided together when guiding the laser beam 16.

[0063] The laser beam 16 is generated by a laser beam source 8 and is guided to the cutting head 3, for example, through a beam duct and a plurality of deflection mirrors or an optical fiber cable. By means of a focusing lens or adaptive optics, the laser beam 16 can be aligned in a focused form (i.e., focused) onto the workpiece. Due to the mobility of the cutting head 3 along the first axis direction (x-direction) and the second axis direction (y-direction), the laser beam 16 can be moved to any arbitrary point on the workpiece 9.

[0064] The workpiece 9 has two mutually opposed workpiece surfaces 17, 20 (for example, see Figure 23), wherein the first or upper workpiece surface 17 faces the cutting nozzle 13, and the second or lower workpiece surface 20 faces away from the cutting nozzle 13. By the height mobility of the cutting head 3 in the z direction, the working distance between the cutting nozzle 13 and the workpiece 9 can be adjusted by changing the distance from the upper workpiece surface 17. The distance between the cutting head 3 and the upper workpiece surface 17 can be adjusted before, during, and after the laser beam machining. The focal position of the laser beam 16 can be adjusted by changing the distance between the cutting nozzle 13 and the upper workpiece surface 17 and / or by optical elements in the cutting head 3, such as adaptive optics.

[0065] The process gas 25 is used to expel the melt from the cut. The process gas is generated by a gas beam generating device (not shown). As an inert process gas, for example, helium (He), argon (Ar), or nitrogen (N2) is used. As a reactive process gas, oxygen (O2) is generally used. It is also known to use gas mixtures. The process gas has a pre-given process gas pressure (tank pressure) within the cutting head 3, is ejected from the cutting nozzle 13 at this pressure, and is guided coaxially with the laser beam 16 to the machining site.

[0066] As shown in Figure 1 the planar workpiece support 5 consists of, for example, a plurality of support elements, which, for example, have load point tips (Tragpunktspitzen) with a triangular configuration, and these load point tips together define a support plane for the workpiece 9 to be machined. The support elements are, for example, implemented as elongated support bars, which each extend along the y direction and are arranged side by side along the x direction in a parallel arrangement at, for example, a constant spacing. A suction device is not further shown, by which the cutting smoke, residue particles, and small waste parts generated during the laser cutting can be sucked away.

[0067] The program-controlled control device 12 is used to control / regulate the method for laser machining the workpiece 9 in the laser machining apparatus 1 according to the present invention.

[0068] Furthermore, the configuration of the method of the present invention is described, in which a workpiece part 11 is cut off from the workpiece 9, and the workpiece 9 is modified on the cutting edge side of the workpiece part of the workpiece part that is still connected to the remaining workpiece (i.e., the remaining workpiece) to produce a rounded area, a chamfered area, or a counterbored area. Here, in a first machining step, a section of the cut is produced, and in at least one second machining step, a rounded area, a chamfered area, or a counterbored area is produced on the cutting edge side of the workpiece part of the cut by modifying the workpiece. Refer to Figures 2 to 16 , which corresponds to the respective subsequent method states in this order.

[0069] First, look at Figure 2, in which a cutting line 14 (dashed line) is shown. The cutting line 14 is an imaginary line corresponding to the contour of the workpiece part 11 to be manufactured from the workpiece 9. This contour reflects the external shape of the workpiece part 11. The workpiece part 11 is to be completely cut off from the plate-shaped or tubular workpiece 9, which is not further shown, with the remaining workpiece 10 being retained. The workpiece part 11 has, for example, a rectangular shape with rounded corners here, where the workpiece part 11 can of course have any arbitrary shape.

[0070] In Figure 3 , the laser beam 16 emitted from the cutting head 3 is schematically and visually shown. The laser beam 16 is guided along the cutting line 14, where a cutting gap 15 is produced in the workpiece 9 in the case of the corresponding energy per unit length of the laser beam 16 on the workpiece 9. For this purpose, the cutting head 3 has been moved to a position above the cutting line 14, in which the laser beam 16 reaches the first cutting position A of the cutting line 14. As is visually shown in Figure 3 , the cutting head 3 is moved along the cutting line 14, where the laser beam 16 is moved from the cutting position A to the cutting position B. Thereby, a section 15-1 (solid line) of the cutting gap 15 that completely separates the workpiece 9 is produced from the cutting position A to the cutting position B. The first section 15-1 of the cutting gap 15 is produced in the first section 14-1 of the cutting line 14. The laser beam 16 can also penetrate into the workpiece 9 away from the cutting line 14, where the cutting gap 15 extends only along the contour of the workpiece part 11 (i.e., the cutting line 14) in the sense of the present invention.

[0071] In Figure 4 , the situation is shown where the first section 15-1 of the cutting gap 15 has been completely produced from the cutting position A to the cutting position B. The separation process of the workpiece 9 is now interrupted. The laser beam 16 is turned off, and the cutting head 3 is moved to a reprocessing position A' close to the cutting position A (see Figure 5 ). As is visually shown by the arrow in Figure 4 , the displacement movement of the cutting head 3 is carried out, for example, linearly between the cutting position B and the reprocessing position A'. The reprocessing position A' is located on a reprocessing line 18, which is used to produce a rounded area 34 (see Figure 25 and 26) or a chamfer or counterbore area 21 (see Figure 23 ) as the reprocessing of the workpiece 9.

[0072] As is shown in Figure 5 and another Figures 6 to 16As shown, the reprocessing line 18 is laterally offset and arranged equidistant from the cutting line 14. When reprocessing the workpiece 9, the cutting head 3 is moved along the reprocessing line 18, wherein the displacement movement of the cutting head 3 can be linear or non-linear along the reprocessing line 18, as will be further elaborated below. The reprocessing of the workpiece 9 is carried out in the reprocessing zone 22, which typically has a wider dimension perpendicular to its extension scale than the reprocessing line, which is not shown in the illustration. The reprocessing zone 22 can be understood as the area of the workpiece 9 that is modified by laser irradiation. Corresponding to the reprocessing line 18, the reprocessing zone 22 also extends along the cutting line 14. The cutting gap 15 is delimited by two opposing cutting edges 19, 19' (see, for example, Fig. 23).

[0073] As intuitively shown in 5, the laser beam 16 is then switched on again, and the cutting head 3 is moved along the reprocessing line 18 (dashed line), wherein the laser beam 16 is moved from the first reprocessing position A' to the second reprocessing position B' close to the cutting position B. Here, the reprocessing of the workpiece 9 in the first section 22-1 of the reprocessing zone 22 is achieved.

[0074] In Figure 6 it is shown that the workpiece 9 has been modified along the entire first section 15-1 of the cutting gap 15. The modified area or the first section 22-1 of the reprocessing zone 22 is schematically shown in solid lines. Similar to the generation of the section of the cutting gap 15, the reprocessing zone 22 is also generated section by section.

[0075] As in Figure 6 it is intuitively shown, now the workpiece 9 is processed separately starting from the cutting position B, wherein the already generated first section 15-1 of the cutting gap 15 is extended to the cutting position C.

[0076] In Figure 7 it is intuitively shown that another section or the second section 15-2 of the cutting gap 15 has been generated along the second section 14-2 of the cutting line 14 from the cutting position B to the cutting position C. Now the separation processing of the workpiece 9 is interrupted. The laser beam 16 is switched off, and the cutting head 3 is linearly moved to a position above the reprocessing position B', as intuitively shown by the arrow.

[0077] As in Figure 8 it is intuitively shown, now the laser beam 16 is switched on again, and the cutting head 3 is moved along the reprocessing line 18, wherein the laser beam 16 is moved from the reprocessing position B' to the reprocessing position C' close to the cutting position C.

[0078] In Figure 9The following situation is shown, in which the workpiece 9 has been reshaped in another section or the second section 22-2 of the reprocessing area 22 along the entire second section 15-2 of the cutting gap 15 between the reprocessing position B' and the reprocessing position C'. The second section 22-2 of the reprocessing area 22 extends the previously generated first section 22-1 of the reprocessing area 22.

[0079] As is visually shown in Figure 9 the workpiece 9 is then processed separately and continuously starting from the cutting position C, wherein the already generated part of the cutting gap 15 is extended to the cutting position D.

[0080] In Figure 10 the following situation is visually shown, in which a third section 15-3 of the cutting gap 15 has been generated along the third section 14-3 of the cutting line 14 from the cutting position C to the cutting position D. Now the separation processing of the workpiece 9 is interrupted. The laser beam 16 is switched off, and the cutting head 3 is moved to a position above the reprocessing position C' on the reprocessing line 18 for subsequent reprocessing now. The third section 15-3 of the cutting gap 15 extends the second section 15-2 of the cutting gap 15.

[0081] As is visually shown in Figure 11 the laser beam 16 is now switched on again, and the cutting head 3 is moved along the reprocessing line 18, wherein the laser beam 16 is moved from the reprocessing position C' to the reprocessing position D' close to the cutting position D.

[0082] In Figure 12 the following situation is shown, in which the workpiece 9 has been reshaped along the entire third section 15-3 of the cutting gap 15 from the reprocessing position C' to the reprocessing position D' in the third section 22-3 of the reprocessing area 22. The third section 22-3 of the reprocessing area 22 extends the previously generated second section 22-2 of the reprocessing area 22.

[0083] As is visually shown in Figure 12 the workpiece 9 is now processed separately and continuously starting from the cutting position D, wherein the already generated part of the cutting gap 15 is extended to the cutting position E.

[0084] In Figure 13 the following situation is visually shown, in which a fourth section 15-4 of the cutting gap 15 has been generated along the fourth section 14-4 of the cutting line 14 from the cutting position D to the cutting position E. The separation processing of the workpiece 9 is interrupted. The fourth section 15-4 of the cutting gap 15 extends the third section 15-3 of the cutting gap 15.

[0085] The laser beam 16 is now switched off, and the cutting head 3 is moved to a position above the reprocessing position D' on the reprocessing line 18 for subsequent reprocessing.

[0086] As is visually shown in Figure 14 the laser beam 16 is switched on again, and the cutting head 3 is moved along the reprocessing line 18, wherein the laser beam 16 is moved from the reprocessing position D' to the reprocessing position E' close to the cutting position E.

[0087] In Figure 15 it is shown the situation where the workpiece 9 has been reshaped in the fourth section 22-4 of the reprocessing zone 22 along the entire fourth section 15-4 of the cutting gap 15 from the reprocessing position D' to the reprocessing position E'. The fourth section 22-4 of the reprocessing zone 22 extends the previously produced third section 22-3 of the reprocessing zone 22.

[0088] As is visually shown in Figure 15 the workpiece 9 is subsequently processed separately starting from the cutting position E, wherein the already produced part of the cutting gap 15 is extended along the fifth section 14-5 of the cutting line 14 up to the cutting position A. Thereby the cutting gap 15 is closed and the workpiece part 11 is cut off from the remaining workpiece 10 so that it can be removed. The cut-off workpiece part 11 is not further reprocessed here because no reprocessing is carried out on the cut-off workpiece part 11 by this method. Here a fifth section 15-5 of the cutting gap 15 is produced, which extends the fourth section 15-4 of the cutting gap 15.

[0089] In all separation processes, the laser beam 16 has an energy per unit length, which is determined such that the workpiece 9 is completely separated, i.e., the laser beam 16 is in the separation mode. In all reprocessing of the workpiece 9 for producing a rounded zone, a chamfered zone or a countersunk zone, the laser beam 16 has an energy per unit length, which is determined such that the workpiece 9 is processed without bonding or separation, i.e., the laser beam 16 is in the non-separation mode. The beam axis of the laser beam 16 is, for example, axially parallel to the conical cutting nozzle 13 and perpendicular to the workpiece 9. In all separation processes and all reprocessing, the laser beam 16 is aligned with its beam axis in a constant perpendicular orientation relative to the upper workpiece surface 17.

[0090] The reprocessing of workpiece 9 can be changed in various ways. For example, the reprocessing position can also be positioned such that workpiece 9 is modified only along a part of the respective sections 14-1 to 14-5 of cutting line 14 or along a part of the respective sections 15-1 to 15-5 of cutting gap 15, i.e., the respective sections 22-1 to 22-4 of reprocessing zone 22 do not extend over the entire length of the respective sections 14-1 to 14-5 of cutting line 14 or over the entire length of the respective sections 15-1 to 15-5 of cutting gap 15. For example, the direction for generating the reprocessing can also be opposite to the direction for generating cutting gap 15.

[0091] As can be seen, especially from Figure 16 it can be seen that in the last (fifth) separation step, section 15-5 of cutting gap 15 is generated, and its length is less than the corresponding lengths of the sections of cutting gap 15 generated in all previous separation processes. By this measure, it can be advantageously achieved that as small a part as possible of cutting gap 15 is not subjected to reprocessing. It can also be that the length of the part of cutting gap 15 generated in the separation step continuously increases, for example, starting from the cutting point of workpiece part 11.

[0092] Regarding the complete reprocessing of workpiece part 11, the following configuration of the method according to the invention is particularly advantageous. Here, after modifying workpiece 9 in the fourth section 22-4 of reprocessing zone 22, but before generating the fifth section 15-5 of cutting gap 15, i.e., before removing workpiece part 11, reprocessing of workpiece 9 is carried out between reprocessing positions E' and A' along the fifth section 14-5 of cutting line 14. This is schematically illustrated according to the inserted annotation in Figure 15 Here, the fourth section 22-4 of reprocessing area 22 is extended to reprocessing position A'. Thus, the extended fourth section 22-4' of reprocessing area 22 extends to reprocessing position A' here, such that reprocessing zone 22 extends completely over the entire contour of workpiece part 11 as a closed elongated area. In particular, in such reprocessing, it is advantageously possible to generate a chamfering zone on one or both of the two subsequent cutting edges to be generated of cutting gap 15, also in the area of the fifth section 14-5 of cutting line 14. Immediately thereafter, workpiece part 11 is removed by generating the fifth section 15-2 of cutting gap 15.

[0093] Of course, the number of sections 14-1 to 14-5 of cutting line 14 or sections 15-1 to 15-5 of cutting gap 15 is exemplary in the Figures 2 to 16 configuration and can be larger or smaller.

[0094] According to Figures 2 to 16An exemplary embodiment of the method has been described, in which the workpiece 9 is first separated and then reprocessed in an alternating sequence. It is also possible to first generate different sections of the cutting gap 15, which are separated from each other by webs, in particular micro- or nano-joints, and then reprocess the workpiece 9. This is according to Figure 17 and 18 are shown intuitively.

[0095] As in Figure 17 As shown in FIG. 1 , according to another embodiment of the method according to the invention, three sections 15-1, 15-2, 15-3 of the cutting slit 15 are first produced, which are separated from one another by webs 23, in this case micro-joints or nano-joints. To produce the sections 15-1, 15-2, 15-3 of the cutting slit 15, the laser beam 16 is respectively inserted away from the contour of the workpiece part 11, first guided to the contour of the workpiece part 11 and then guided along the contour. The cutting slit 15 is formed along the workpiece part 11. Figure 17 A cutting line 14 (not shown in detail) is produced. Of course, a greater or smaller number of sections of the cutting gap 15 can be provided along the contour of the workpiece part 11 , wherein the number of sections of the cutting gap 15 corresponds to the number of webs 23 .

[0096] like Figure 18 , after the production of the three sections 15-1, 15-2, 15-3 of the cutting gap 15, the workpiece 9 is reprocessed on the cut edge 19 on the workpiece part side in order to produce a rounded area 34, a chamfer or a countersunk area 21, wherein the laser beam 16 is guided along a reprocessing line 18. The reprocessing line 18 is arranged transversely offset and equidistant from the cutting line 14. The reprocessing line 18 in particular also extends over the region of the cutting line 14 in which the web 23 is arranged, i.e. the workpiece 9 is also reprocessed in the region of the web 23. As experiments have shown, the reprocessing of the workpiece 9 can be adequately achieved with webs 23 of correspondingly small design dimensions, since the gas dynamics of the process gas are only slightly affected thereby.

[0097] After the reprocessing of the workpiece 9 to produce the rounded area 34, the chamfered or countersunk area 21, the tab 23 is cut off, for example by means of a laser beam 16 or manually, and the workpiece part 11 is removed from the remaining workpiece 10. It is also conceivable that the tab 23 is already cut off in the region of the tab 23 by the reprocessing of the workpiece 9, so that the workpiece part 11 is cut off at the same time by the reprocessing. This can be the case in particular if the tab 23 is designed as a micro joint with a reduced height.

[0098] When producing the cutting gap 15, the laser beam 16 is always guided in a straight line along the cutting line 14 (contour) of the workpiece part 11. During the further processing of the workpiece 9, the laser beam 16 is guided in a straight line or non-straight line along the further processing line 18. In particular, during the further processing of the workpiece 9, the laser beam 16 can also have a movement component transversely (perpendicularly) to the further processing line 18, wherein a secondary movement is superimposed on the primary movement. This is in accordance with Figures 19 to 22 Intuitively shown.

[0099] exist Figures 19 to 22 1 shows different exemplary configurations for guiding the laser beam 16 along the processing line 18. For the sake of simplicity of illustration, it is assumed that the processing line 18 extends horizontally from left to right. The movement of the laser beam 16 on the processing line 18 corresponds to a primary movement, which is superimposed on a secondary movement having a movement component transversely (perpendicularly) to the processing line 18.

[0100] exist Figure 19 , a variant is shown schematically in which the laser beam 16 is guided along a closed circle 24 (i.e. a closed trajectory section of the laser beam 16) which is arranged in a row along the reprocessing line 18. After passing the respective circle 24, the laser beam 16 is each moved linearly along the reprocessing line 18 for a distance and then guided along the next circle 24. The circles 24 overlap in the direction of the reprocessing line 18. Instead of a circle, the laser beam 16 can also be guided along an ellipse. The movement of the laser beam 16 thus has a movement component that is linear along the reprocessing line 18 and a movement component that is transverse to the reprocessing line 18. The reprocessing zone 22, which is generated by the area of the workpiece 9 that is swept by the laser beam 16, can be designed relatively wide by this measure, in particular for producing deep and / or wide chamfers or countersunk areas.

[0101] exist Figures 20 to 22 , in each case variants are shown schematically, in which the laser beam 16 is guided in a meandering manner with a reciprocating motion along the processing line 18. In this case, the motion of the laser beam 16 also includes a motion component transverse to the processing line 18. Figure 20 In the figure, the meandering motion of the laser beam 16 forms a rectangle. Figure 21 In the triangle (zigzag), Figure 22 This is to be understood only as an example, wherein other meandering movements of the laser beam 16 are likewise possible. Basically, according to the invention, any meandering reciprocating movement of the laser beam 16 extending along the reprocessing line 18 can be realized and provided. By means of the meandering movement of the laser beam 16, a relatively wide reprocessing zone 22 can also be produced, in particular for producing particularly deep and / or wide chamfers or countersunk zones.

[0102] exist Figure 23 and 24The generation of the chamfer or countersink region 21 is visually shown therein. Figure 24 According to the perspective view, it shows how to guide the cutting head 3 or the laser beam 16 along the cutting gap 15 in order to generate the chamfer or countersink region 21. As can be clearly seen in the Figure 23 cross-sectional view (a section perpendicular to the plane of the workpiece 9), when the workpiece 9 is reprocessed by the laser beam 16, a chamfer or countersink region 21 is provided adjacent to the cutting edge 19 on the workpiece part side and the upper workpiece surface 17. The reprocessing line 18 is laterally (e.g., equidistantly) offset relative to the cutting line 14, which is not shown in Figure 23 and 24 Here, for example, the chamfer or countersink region 21 is generated by multiple steps or reprocessing, and these steps or reprocessing are carried out on the same section of the cutting gap. During the first reprocessing, the workpiece part 11 is irradiated in the region including the cutting edge 19 on the workpiece part side. The reprocessing line 18 is laterally (e.g., equidistantly) offset in the direction of the workpiece part 11 relative to the cutting line 14. This can be repeated one or more times if necessary to further construct the chamfer or countersink region 21 further away from the cutting edge 19 on the workpiece part side. Here, the cutting edge 19 on the workpiece part side is not irradiated together. It is also conceivable to first irradiate the workpiece part 11 such that the region not including the cutting edge 19 on the workpiece part side is irradiated, and then the reprocessing line 18 is continuously displaced in the direction of the cutting gap 15, where finally, the cutting edge 19 on the workpiece part side is irradiated together. During the reprocessing of the workpiece 9 for generating the chamfer or countersink region 21, the cutting edge 19 on the workpiece part side is irradiated together in any case during the steps for carrying out the reprocessing.

[0103] Particularly advantageously, the laser beam 16 is curved along the cutting line 14 or moves along an arranged row of circles or ellipses when generating the chamfer or countersink region 21, as visually shown according to Figures 19 to 22 Thereby, the width and / or depth of the chamfer or countersink region 21 can be significantly increased.

[0104] In Figure 25 and 26 it is further elaborated on the generation of the rounded region 34 on the cutting edge 19 on the workpiece part side of the workpiece part 11. In Figure 25 during the reprocessing of the workpiece 9 by the laser beam 16, the cutting edge 19 on the workpiece part side of the workpiece part 11 adjacent to the workpiece surface 17 of the upper workpiece 35 is rounded by remelting, and the rounded region 34 is generated. The reprocessing line 18 is laterally (e.g., equidistantly) offset relative to the cutting line 14, where preferably, the maximum distance between the reprocessing line 18 and the cutting line 14 is half of the cutting gap width of the cutting gap 15 plus the beam cone radius of the laser beam 16 on the workpiece surface 17. This is in Figure 25is not shown in. In Figure 26 while reprocessing the workpiece 9 by means of the laser beam 16, the cutting edge 19 on the workpiece part side adjacent to the workpiece surface 20 on the lower side 36 of the workpiece is rounded, a rounding region 34 being produced and the cutting edge 19' on the remaining workpiece side adjacent to the workpiece surface 17 being flattened. The reprocessing line 18 is laterally (for example equidistantly) offset relative to the cutting line 14, which is not shown in Figure 26 is not shown.

[0105] In Figure 27 a sectional view perpendicular to the plane of the workpiece 9 schematically shows intuitively the production of a chamfer or counterbore region 21 or a rounding region 34 along the cutting gap 15 on the cutting edge 19 on the workpiece part side. The displacement movement of the laser processing head 3 along the cutting gap 15 or along the cutting edge 19 on the workpiece part side is indicated by the arrow. The processing beam 26 comprises the laser beam 16 and the process gas 25. The melt formed when producing the chamfer or counterbore region 21 or the rounding region 34 is expelled by the process gas 25 through the cutting gap 15.

[0106] According to Figures 28A to 28C and the configurations of the method according to the invention shown intuitively in 29A to 29D can be carried out in two steps or alternatively in three steps, in which holes each having a chamfer or counterbore region are produced in the workpiece. The workpiece part is a region of the remaining workpiece (residual workpiece) and is provided for being cut off from the workpiece after one or more holes (each of which is provided with a chamfer or counterbore region) have been produced. The holes having the corresponding chamfer or counterbore regions are typically constructed in the workpiece part to be cut off from the workpiece.

[0107] In the variant with two steps, first a hole-shaped notch is cut out of the workpiece with the formation of a waste piece and a workpiece part. The outer contour of the waste piece and the inner contour of the hole-shaped notch in the workpiece part are pre-given by the cutting line, one of the two cutting edges being the cutting edge on the workpiece part side and the other of the two cutting edges being the cutting edge on the waste piece side. Immediately afterwards, the cutting edge on the workpiece part side is machined in order to produce a chamfer or counterbore region on the cutting edge on the workpiece part side. In the variant with three steps, first a hole-shaped notch is cut out of the workpiece, a prefabricated hole being produced with the formation of a waste piece and a workpiece part. Immediately afterwards, the cutting edge on the workpiece part side is machined in order to produce a chamfer or counterbore region on the cutting edge on the workpiece part side. Immediately afterwards, the prefabricated hole is enlarged in order to produce the final hole.

[0108] For easier reference, the hole produced in the workpiece in the first step is referred to as a "hole" or "pre-hole", depending on whether the hole provided with a chamfer or countersunk area, respectively, is produced in two steps or in three steps. Only in the case of a three-step implementation, the hole represents a pre-hole, from which the final hole is produced by widening. The term "(pre-)hole" can therefore relate to the implementation of the method in two or three steps. Accordingly, the term "pre-hole cutting line" is used for the cutting line for producing the pre-hole, while the term "final hole cutting line" is used for the cutting line for producing the final hole. The names "pre-hole" and "final hole" used for the hole produced with a countersunk in three steps serve only to distinguish between different stages of the method for producing a hole with a chamfer or countersunk area, wherein the final hole is produced by widening the pre-hole. With the production of the final hole in the chamfer or countersunk head, the finished hole is produced.

[0109] Now refer to Figures 28A to 28C and 29A to 29D, which intuitively illustrate the Figure 1 1 is an exemplary embodiment of a method according to the invention of a laser beam device 1 for laser beam processing of a workpiece 9. For reasons of simplicity of the illustration and for a full understanding of the invention, only the cutting nozzle 13 as well as the laser beam 16 and the process gas 25 are shown in each case in conjunction with the workpiece 9. The workpiece 9 is located in a horizontal position on the workpiece support 5 as usual.

[0110] First observe Figures 28A to 28C , in which a vertical sectional view of a plate-shaped workpiece 9 with two planar workpiece surfaces 17 , 20 and a cutting nozzle 13 are schematically shown in each left-hand view. Figures 28A to 28C The right side view of the embodiment of the present invention schematically shows the method steps according to the corresponding top view. The upper workpiece surface 17 faces the cutting nozzle 13, and the lower workpiece surface 20 faces away from the cutting nozzle 13. The laser beam 16 and the process gas 25 emitted from the nozzle tip 33 of the cutting nozzle 13 reach the workpiece 9. The laser beam 16 has a focused beam cone shape with a central beam axis 27. The central beam axis 27 and therefore the laser beam 16 are oriented perpendicular to the upper workpiece surface 17. Coaxially with the laser beam 15, the process gas 25 is emitted from the cutting nozzle 13, wherein the laser beam 16 and the process gas 25 are guided together by the cutting nozzle. The processing beam 26 includes the laser beam 16 and the process gas 25.

[0111] exist Figure 28AThe cutting nozzle 13 is moved from the initial position towards the workpiece 9 with at least a vertical component of movement such that the cutting nozzle 13 has a small working distance A from the workpiece 9. Preferably, the working distance A between the cutting nozzle 13 and the upper workpiece surface 17 is less than 2 mm. The focal position of the laser beam 16 causes a narrow beam spot with a small beam diameter on the workpiece 9. The focal position and thus the beam diameter are selected such that the laser beam 16 can be so large per unit length on the workpiece 9 that the laser beam 16 is suitable for cutting or separating the workpiece 9.

[0112] As shown in Figure 28A , the cutting laser beam 16 is guided along a circular pre - drilled hole cutting line 32 for producing a (pre - drilled) hole 28, thereby producing a circular closed cutting gap. Thereby, a waste piece (central slug) with a circular or disc - shaped cross - section is completely cut off from the workpiece 9. The cut - off central slug drops down due to its own weight. By removing the central slug from the workpiece 9, a (pre - drilled) hole 28 with a circular cross - section is produced in the workpiece 9. The diameter of the (pre - drilled) hole 28 is measured in the plane of the workpiece 9. The (pre - drilled) hole 28 can optionally be used in a further method to produce an enlarged hole, i.e., the final hole 29, by widening its diameter (see Figure 28C ).

[0113] The circular (pre - drilled) hole 28 is a through - hole according to its manufacturing method and penetrates the workpiece 9, wherein the (pre - drilled) hole 28 is surrounded by a pre - drilled hole wall 38 formed by the workpiece 9, and the pre - drilled hole wall continuously extends from the upper workpiece surface 17 to the lower workpiece surface 20. On the upper workpiece surface 17, the (pre - drilled) hole 28 is surrounded by a circular upper (pre - drilled) hole cutting edge 30, and on the lower workpiece surface 20, the (pre - drilled) hole 28 is surrounded by a circular lower (pre - drilled) hole cutting edge 31. The two (pre - drilled) hole cutting edges 30, 31 are each part of the (pre - drilled) hole wall 38. In Figure 28A , the (pre - drilled hole) cutting line 32 and the upper (pre - drilled) hole cutting edge 30 are shown relatively far apart based on a clearer view, where of course, this does not have to be the case in practice. The circular (pre - drilled) hole 28 is constructed radially symmetrically about its central axis 46 (see Figure 28B ). In the plane of the workpiece 9, a radial direction is defined with respect to the (pre - drilled) hole 28 and its central axis 46.

[0114] Optionally, a step can be added to the method, which is carried out before cutting the (preformed) hole 28. This step is preferably used if (preformed) holes 28 with a diameter of at least 7 mm are to be manufactured and / or if the workpiece 9 has a thickness of at least 4 mm. Here, the central blank to be cut out subsequently along its contour is divided into smaller parts by one or more cutting slits, whereby it is always possible to ensure that the central blank drops down from the workpiece 9 reliably and safely and the cut (preformed) hole 16 is always empty. For example, intersecting cutting slits are introduced in the area of the central blank to be cut out, if necessary by overlapping spiral cutting slits. Possible methods for dividing the central blank are described, for example, in document US 8716625B2.

[0115] After the circular (preformed) hole 28 is produced, a circular chamfer or counterbore region 21 concentric with the (preformed) hole 28 is produced. This is also shown Figure 28B intuitively.

[0116] For the production of the chamfer or counterbore region 21, the cutting nozzle 13 has a relatively large working distance A from the first workpiece surface 17, where the workpiece 9 is located in the divergence region of the laser beam 16, which results in a wide beam spot with a large beam diameter on the workpiece 9. For this purpose, the cutting head 3 or the cutting nozzle 13 is moved away from the workpiece 9 at least with a vertical movement component, such that there is a greater working distance A between the cutting nozzle 13 and the first workpiece surface 17 compared to the production of the (preformed) hole 28. The working distance A for manufacturing the chamfer or counterbore region 21 is, for example, at least 6 times larger, in particular at least 10 times larger, and preferably at least 30 mm, particularly preferably at least 40 mm and in particular approximately 50 mm, compared to the working distance A for producing the (preformed) hole 28, where a range of 30 mm to 50 mm is preferred. Accordingly, the beam spot and the beam diameter on the workpiece 9 are larger. For example, the cross-sectional area of the beam spot on the workpiece 9 is at least 6 times larger, in particular at least 10 times larger. The focus of the laser beam 16 is located far above the workpiece 9. The focus position and the beam diameter of the laser beam 16 are selected such that the laser beam 16 has a relatively small energy per unit length on the workpiece 9 and the laser beam 16 only produces the chamfer or counterbore region 21 and does not penetrate the workpiece 9 (non-separating machining). The laser beam 16 is in a non-cutting mode.

[0117] When producing the chamfer or counterbore area 21, the non-cutting laser beam 16 is moved in a (horizontal) plane parallel to the plane of the workpiece support 5, wherein the laser beam 16 is moved along at least one chamfer or counterbore generating line 44. At least one chamfer or counterbore generating line 44 extends concentrically with the (pre-drilled hole) cutting line 32 and along the upper (pre-drilled) hole cutting edge 30, wherein the chamfer or counterbore generating line 44 corresponds, for example, to the upper (pre-drilled) hole cutting edge 30 or is preferably further radially offset outwards for this purpose. This means that: the chamfer or counterbore generating line 44 has a diameter which is equal to or preferably greater than the diameter of the upper (pre-drilled) hole cutting edge 30.

[0118] For producing the chamfer or counterbore area 21, a single chamfer or counterbore generating line 44 can be provided, wherein the laser beam 16 is moved along the chamfer or counterbore generating line 44 one or more times for producing the chamfer area 21. Preferably, the laser beam 16 is moved along the chamfer or counterbore generating line 44 a plurality of times for producing the chamfer or counterbore area 21 (typically, the cutting nozzle 13 is moved 2 to 20 times). The offset (i.e., the radial spacing) of the chamfer or counterbore generating line 44 from the upper (pre-drilled) hole cutting edge 30 is preferably at least 0.5 mm, particularly preferably at least 1 mm and especially 2 mm. The chamfer or counterbore generating line 44 must be arranged such that the produced chamfer or counterbore area 21 directly adjoins the (pre-drilled) hole 28, i.e., leads into the (pre-drilled) hole 28.

[0119] For producing the chamfer or counterbore area 21, a plurality of chamfer or counterbore generating lines 44 can also be provided, wherein the laser beam 16 is moved along each of the chamfer or counterbore generating lines 44 one or more times for producing the chamfer or counterbore area 21. Preferably, the laser beam 16 is moved along each of the chamfer or counterbore generating lines 44 a plurality of times for producing the chamfer or counterbore area 21 (typically, the cutting nozzle 13 is moved 2 to 20 times). The plurality of chamfer or counterbore generating lines 44 are arranged concentrically relative to one another. The offset of the chamfer or counterbore generating line 44 from the upper (pre-drilled) hole cutting edge 30 or the offset (i.e., the radial spacing) between two directly adjacent chamfer or counterbore generating lines 44 is preferably 0.25 mm to 1 mm. Thus, the diameter increase of two directly adjacent chamfer or counterbore generating lines 44 is preferably 0.5 mm to 1 mm. The chamfer or counterbore generating line 44 must be arranged such that the produced chamfer or counterbore area 21 directly adjoins the (pre-drilled) hole 28, i.e., leads into the (pre-drilled) hole 28.

[0120] In Figure 28B the circular movement of the laser beam 16 along at least one chamfer or counterbore generating line 44 around the central axis 46 of the (pre-drilled) hole 28 is schematically shown visually by an arrow.

[0121] It is also possible to consider moving the laser beam 16 along the chamfer or counterbore generation line 44 of a spiral configuration for generating the chamfer or counterbore region 21. Preferably, an increase in the radius of the spiral trajectory from 0.25 mm to 1 mm is achieved in a correspondingly complete revolution. After reaching the target diameter, it is advantageous to move past the target diameter several times. In this case, the chamfer or counterbore generation line 44 must also be arranged such that the generated chamfer or counterbore region 21 directly abuts the (preformed) hole 28, i.e., leads into the (preformed) hole 28.

[0122] The chamfer or counterbore region 21 is a recess in the workpiece 9 on the first workpiece surface 17. The chamfer region 21 concentrically surrounds the (preformed) hole 28, wherein the chamfer or counterbore region 21 starts from the (radial) outer chamfer or counterbore edge 42 and extends into the workpiece 9 from the upper workpiece surface 17 to the (radial) inner chamfer or counterbore edge 43, but does not extend to the lower workpiece surface 20, i.e., the chamfer or counterbore region 21 does not extend over the entire thickness of the workpiece part. The inner chamfer or counterbore edge 43 is thus located between the upper workpiece surface 17 and the lower workpiece surface 20.

[0123] The outer chamfer or counterbore edge 42 is defined as the region of the workpiece 9 where the chamfer or counterbore region 21 starts to deepen towards the interior of the workpiece 9. The inner chamfer or counterbore edge 42 is defined as the region of the workpiece 9 where the chamfer or counterbore region 21 transitions into the remaining part of the (preformed) hole 28, wherein the inner chamfer or counterbore edge 42 is formed by the (preformed) hole wall 38. The side surface 45 of the chamfer or counterbore region 21 extends from the outer chamfer or counterbore edge 42 to the inner chamfer or counterbore edge 43.

[0124] In the radial direction, the chamfer or counterbore region 21 can optionally be provided with a defined cross-sectional shape. In particular, the focal position and thus the beam diameter can be varied during the generation of the chamfer or counterbore region 21 in order to adjust the depth and / or cross-sectional shape of the chamfer or counterbore region 21 in a targeted manner. When the beam diameter on the workpiece 9 decreases, the chamfer or counterbore region 21 becomes deeper, i.e., the side surface 45 of the chamfer or counterbore region 21 becomes steeper. In contrast, if the beam diameter on the workpiece 9 increases, the chamfer or counterbore region 21 becomes flatter, i.e., the side surface 45 of the chamfer or counterbore region 21 becomes less steep. In Figure 28B FIG. shows an exemplary chamfer or counterbore region 21 with an inclined side surface 45 having an inclination of approximately 45°, wherein a greater or smaller side surface inclination is also possible.

[0125] The chamfer or counterbore area 21 can in principle be used in any way, wherein, in this embodiment, the chamfer or counterbore area is preferably provided for receiving the head of a countersunk bolt. Preferably, the radially outermost chamfer or counterbore generating line 44 has a diameter for generating the chamfer or counterbore area 21 that is slightly smaller than the maximum diameter of the head of the countersunk bolt to be arranged in the chamfer or counterbore area 21. The number of chamfer or counterbore generating lines 44 is related to the diameter of the (preformed) hole 28 or to the thread diameter of the bolt to be inserted and the desired depth of the chamfer or counterbore area 21. Generally, for a (preformed) hole 28 for receiving a countersunk bolt with a metric thread size M3 to M6 (i.e., in the case of a (preformed) hole 28 with a diameter of 3 to 6 mm), the cutting nozzle 13 needs to be moved across the same chamfer or counterbore generating line 44 at least twice, wherein the typical number of moves is between 2 and 25. For countersunk bolts with a metric thread size M8 to M12, the number of moves is generally at least 5, preferably at least 10 and typically between 10 and 25. As the process gas, for example, oxygen (O2) is used when generating the chamfer or counterbore area 21, which has a gas pressure, for example, of less than 5 bar, especially between 2 and 3.5 bar. The feed rate of the cutting nozzle 13 when generating the chamfer or counterbore area 21 is preferably at least 4 m / min and the laser power of the laser beam 16 is preferably at least 1500 W.

[0126] Through the (preformed) hole 28, the melt (slag) formed when generating the chamfer or counterbore area 21 can advantageously flow out downward very well, and thus it can be prevented that the melt reaches the upper workpiece surface 17 of the workpiece 9 and solidifies there and forms burrs. These burrs not only interfere with the subsequent use of the chamfer or counterbore area 21, but may also require laborious reprocessing of the chamfer or counterbore area 21, and in the worst case may also lead to a collision with the cutting nozzle 13. By an optional segmentation of the central slug to be cut off when generating the (preformed) hole 28, it can always be ensured that the (preformed) hole 28 is empty, and the melt accumulated when generating the chamfer or counterbore area 21 is reliably and safely expelled through the (preformed) hole 28 by means of the process gas. This is a major advantage of the present invention.

[0127] Similarly, the melt may deposit on the (preformed) hole wall 38, especially also in the region of the lower (preformed) hole cutting edge 31, and form burrs 37 after cooling, as visually shown in Figure 28B However, these burrs 37 advantageously are removed when generating the final hole 29 (see Figure 28C) When the (preformed) hole 28 is optionally widened, it is removed together, so that a final hole 29 with a burr-free final hole wall 39 can be produced. If this additional step is carried out, the hole 28 produced so far constitutes a "preformed hole", which is widened in its diameter to the final hole 29.

[0128] In addition, an optional widening of the diameter of the hole or preformed hole 28 for producing the final hole 29 is described:

[0129] Here, after producing the chamfer or counterbore area 21, the preformed hole 28 or the remaining part of the preformed hole after producing the chamfer or counterbore area 21 is widened, which is also shown intuitively according to Figure 28C shown intuitively.

[0130] To increase the diameter of the preformed hole 28, similar to producing the preformed hole 28, a laser beam 16 is used in the cutting mode. Here, the cutting nozzle 13 has a relatively small working distance A from the first workpiece surface 17, which results in a narrow beam spot with a small beam diameter on the workpiece 9. The cutting head 3 or the cutting nozzle 13 is moved towards the workpiece 9 at least with a vertical movement component for this purpose, so that there is a smaller working distance A between the cutting nozzle 13 and the first workpiece surface 17 compared to producing the chamfer or counterbore area 21. The focal position of the laser beam 16 and thus the beam diameter are selected such that the unit length on the workpiece 9 of the laser beam 16 can be relatively large and can penetrate the workpiece 9 (separation machining) here.

[0131] When widening the preformed hole 28, the cutting laser beam 16 is guided along a circular final hole cutting line 37, thereby producing a circular closed cutting gap. The final hole cutting line 37 is arranged concentrically with the preformed hole cutting line 32 and is radially spaced outward therefrom for this purpose, that is, it has a larger diameter than the preformed hole cutting line 32. The final hole cutting line 37 is located in the radial direction between the preformed hole cutting line 32 and the outer chamfer or counterbore edge 42, with the following criterion: the radial area of the side 45 is removed, but not the entire side 45, that is, the chamfer or counterbore area 21 is partially retained. The final hole 29 is thus produced within the chamfer or counterbore area 21. When widening the preformed hole 28, a disk with a hollow cylindrical cross-section is completely cut off from the workpiece 9. The disk drops downward due to its own weight, so that the disk is removed from the workpiece 9.

[0132] By widening the pre-drilled hole 28, a final hole 29 with a circular cross-section is produced in the workpiece 9, which final hole has a larger diameter than the pre-drilled hole 28. The final hole 29 is surrounded by a final hole wall 39 formed by the workpiece 9 and extends from an upper final hole cutting edge 40 (which is located between the upper workpiece surface 17 and the lower workpiece surface 20) to a lower final hole cutting edge 41, which lower final hole cutting edge is formed by the lower workpiece surface 20. The diameter D of the final hole 29 is preferably between 0.5 and 2 mm and in particular is about 1 mm larger than the diameter of the previously produced pre-drilled hole 28. This enables the burrs 37 adhering to the pre-drilled hole wall 38 and on the lower workpiece surface 20 in the region of the lower pre-drilled hole cutting edge 31 to be reliably and safely removed.

[0133] Preferably, a pulsed laser beam 16 is used when widening the pre-drilled hole 28 to produce the final hole 29. This can advantageously be achieved such that the workpiece 9 does not heat up too strongly during the production of the final hole 29, so that the metallic material of the workpiece 9 is firmer at the machining site and a clearly defined or sharp lower final hole cutting edge 41 is produced, which makes it easier for the melt to flow down when widening the pre-drilled hole 28. This measure thus helps to prevent: the melt mainly deposits on the lower workpiece surface 20 and burrs are formed there.

[0134] Preferably, such a pulsed laser beam 16 is used which has an average power of at least 200 W and a pulse peak power of at least 2000 W and a pulse frequency between 10 Hz and 200 Hz. Depending on the workpiece material and the desired edge quality, nitrogen (N2), compressed air or oxygen (O2) can be used as the process gas.

[0135] As shown in Figure 28C it is advantageous that the cutting nozzle 13 is moved downwards so far for the production of the final hole 29 that the cutting nozzle 13 sinks into the chamfer or countersink area 21, i.e. the nozzle tip 33 is below the upper workpiece surface 17 or below the plane defined by the upper workpiece surface 17. This has the particular advantage that neither the laser beam 16 nor the process gas 25 spreads out too strongly at the impact site on the workpiece 9 so that a more accurate cutting can be carried out and a final hole 29 with particularly high precision can be manufactured. This also prevents: the melt formed during the production of the final hole 29 deposits on the upper workpiece surface 17 and burrs are formed there. In addition, the melt can be expelled particularly efficiently through the pre-drilled hole 28 by the particularly strongly focused process gas 25, thus also counteracting the deposition of the melt on the upper workpiece surface 17. This is a great advantage that can be achieved by this measure.

[0136] Advantageously, the (pre - formed) hole 28 and the final hole 29 have a diameter that is equal to or smaller than the workpiece thickness of the workpiece 9. By the method according to the invention, very small holes with chamfers or countersinks can also be manufactured.

[0137] Reference is now made to Figures 29A to 29D , in which another exemplary configuration of the method according to the invention for machining the workpiece 9 with a laser beam by means of a beam device 1 is shown schematically. The method steps of FIGS. 28A, 28B, and 28C correspond to Figure 1 the method steps of Figure 29A , 29B and 29C, where, to avoid unnecessary repetition, reference is made to the above description of Figure 28A , 28B and 28C. The configuration of the method according to the invention shown schematically in FIGS. 29A to 29D differs from the configuration shown schematically according to Figures 28A to 28C only in the Figure 29C method steps.

[0138] Thus, active cooling of the chamfer or countersink region 21 ( Figure 29B ) and the pre - formed hole 28 (or the remaining part of the pre - formed hole 28) is achieved by a gaseous or liquid cooling medium after the chamfer or countersink region 21 is produced and before the pre - formed hole 28 is widened to produce the final hole 29 ( Figure 29D ). As shown schematically in Figure 29C , for this purpose, process gas 25 is advantageously used, where the laser beam 16 is switched off. The impact site on the workpiece 9 is typically loaded with process gas having an (initial) air pressure in the range of 2 to 20 bar. The expanding process gas thus results in very effective cooling of the metallic workpiece 9, where the hotter the workpiece 9 to be cooled, the better the cooling effect. By active cooling, the metallic material of the workpiece 9 is made more firm, thus precisely defining the cutting edge 31 of the lower pre - formed hole, which makes it easier for the melt to flow through the pre - formed hole 28. This measure also helps to be able to adjust the geometry of the final hole 29 very accurately. In addition, it can resist the attachment of burrs to the lower workpiece surface 20.

[0139] As described above, by the method shown schematically according to Figures 28A - 28C and 29A - 29D, a rounded region can also be produced on the cutting edge on the workpiece part side instead of a chamfer or countersink region.

[0140] Example 1:

[0141] Manufacturing a chamfer or countersink region for a countersunk bolt with metric thread sizes M3 - M6 by means of a laser beam.

[0142] First, a prefabricated hole with a diameter smaller by approximately 1 mm than the average core hole diameter of the countersunk bolt is cut out, so that the melt accumulated during the generation of the chamfer or countersunk area in the next step can be expelled through the prefabricated hole.

[0143] Subsequently, with a large distance (approx. 50 mm) between the cutting nozzle and the upper workpiece surface and a fired laser beam, a circular chamfer or countersunk head generation trajectory with a diameter of 5 mm to 15 mm is traversed, where oxygen (O2) is used as the process gas. The number of traverses is related to the depth of the chamfer or countersunk area to be introduced, where generally 2 to 25 traverses are carried out. Thereby, a chamfer or countersunk area for the head of the countersunk bolt is produced. Alternatively, a spiral trajectory is traversed.

[0144] Then, the prefabricated hole is cut to a standard size by the laser beam operating in pulses, where the diameter of the final hole is larger than the diameter of the prefabricated hole by approximately 1 mm. Thereby, the slag adhering in the prefabricated hole and especially on the lower workpiece surface in the area of the cutting edge of the lower prefabricated hole can be reliably removed. Advantageous cutting parameters: pulsed average laser power (pulse frequency 10 Hz): 400 W, pulse peak power: 3000 W or 6000 W, feed: 0.1 m / min, distance between the cutting nozzle and the upper workpiece surface: 1.2 mm, air pressure of the process gas: 3.3 bar.

[0145] Example 2:

[0146] A chamfer or countersunk area for a countersunk bolt with a metric thread size M8 - M12 is manufactured by means of a laser beam.

[0147] Before cutting the prefabricated hole, the central slug is segmented in such a way that cutting slits in the shape of overlapping spirals are introduced into the central slug to be cut off. Thereby, it is ensured that the central slug of the prefabricated hole drops reliably and thus the prefabricated hole is always empty, so that the melt accumulated during the generation of the chamfer or countersunk head can be expelled through the prefabricated hole. Then, a prefabricated hole with a diameter smaller by approximately 1 mm than the average core hole diameter of the countersunk bolt is cut.

[0148] Subsequently, with a large distance (approx. 50 mm) between the cutting nozzle and the upper workpiece surface and a fired laser beam, a circular chamfer or countersunk head generation trajectory with a diameter of 10 mm to 15 mm is traversed, where oxygen (O2) is used as the process gas. The number of traverses is related to the depth of the chamfer or countersunk area to be introduced, where generally 10 to 25 traverses are carried out. Thereby, a chamfer or countersunk area for the head of the countersunk bolt is produced. Alternatively, a spiral trajectory is traversed.

[0149] Then, the prefabricated hole is cut to a standard size by a laser beam operating in pulses, where the diameter of the final hole is approximately 1 mm larger than the diameter of the prefabricated hole. Favorable cutting parameters: pulsed average laser power (pulse frequency 10 Hz): 400 W, pulse peak power: 3000 W or 6000 W, feed: 0.1 m / min, distance between the cutting nozzle and the upper workpiece surface: 1.2 mm, air pressure of the process gas: 3.3 bar.

[0150] Example 3:

[0151] A chamfer or counterbore area for a countersunk bolt with a metric thread size M8 is produced in 8 mm structural steel by means of a laser beam.

[0152] Before cutting the prefabricated hole, the central slug is divided by introducing cutting slits in a cross shape with overlapping spirals into the central slug to be cut off. Oxygen (O2), nitrogen (N2) or compressed air is used as the process gas. Then a prefabricated hole with a diameter of 8 mm is cut, which is approximately 1 mm smaller than the average core hole diameter of the countersunk bolt.

[0153] Subsequently, a track is generated by means of a large distance (approx. 50 mm) between the beam nozzle and the upper workpiece surface and a fired laser beam moving over a circular chamfer or counterbore area with a diameter of 12.6 mm, where oxygen (O2) is used as the process gas. The movement is carried out 17 times, where a chamfer or counterbore area with a diameter of 14 mm and a depth of 4.4 mm to 4.5 mm is produced in the sheet. Alternatively, a spiral track is moved over. Favorable laser parameters: laser power: 4000 W, feed: 10 m / min, distance (A) between the cutting nozzle and the upper workpiece surface: 50 mm, air pressure of the process gas: 3.3 bar, focus diameter: 210 μm / 150 μm.

[0154] Then, a prefabricated hole with a diameter of 9 mm is cut to a standard size by a laser beam operating in pulses, where oxygen (O2) is used as the process gas. Favorable cutting parameters: pulsed average laser power (pulse frequency 10 Hz): 400 W, pulse peak power: 4000 W, feed: 0.7 m / min, distance (A) between the beam nozzle and the upper workpiece surface: 0.7 mm, air pressure of the process gas: 17 bar, focus diameter: 210 μm.

[0155] By means of the above-described configuration of the method according to the invention, holes can be manufactured in a workpiece or workpiece part in a simple and cost-effective manner with high precision and quality, which holes each have a chamfer or countersunk area. The holes with chamfer or countersunk area can be manufactured in two steps, where, in a first step, a hole is manufactured in the workpiece, followed by a second step in which a chamfer or countersunk area (surrounding chamfer or countersunk area) around the hole is formed. Optionally, a third step can be added, where manufacturing a hole with chamfer or countersunk area then comprises three steps: in a first step, a hole is manufactured in the workpiece, which hole forms a pre-hole; followed by a second step in which a chamfer or countersunk area (surrounding chamfer or countersunk area) around the pre-hole is formed; followed by a third step in which the diameter of the pre-hole is widened such that a final hole is produced.

[0156] In Figure 30A and B, the positioning of the cutting nozzle 13 is shown exemplarily, which guides the laser beam 16 and the process gas 25 together. In Figure 30A , the cutting nozzle 13 has a small spacing from the workpiece 9 such that the machining beam is in a separated mode and a cut gap 15 can be produced. In Figure 30B , the cutting nozzle 13 has a large spacing from the workpiece 9 such that the machining beam is in a non-separated mode, and a chamfer or countersunk area 21 (alternatively a rounded area) can be produced on one of the two cutting edges of the cut gap 15.

[0157] In Figure 31 , a flow chart of the method according to the invention is shown. The method comprises at least two successive steps.

[0158] Here, in step I (first machining step), the workpiece is machined with a first machining beam guided along a cutting line, whereby a cut gap is produced in the workpiece through the thickness of the workpiece, which cut gap extends along the cutting line in its length and is delimited in its width by two cutting edges in the workpiece.

[0159] Subsequently, in step II (second machining step), the workpiece is machined with a second machining beam, which second machining beam is guided along a reworking line or area that extends parallel and offset to one of the two cutting edges, whereby a rounded area or a chamfer or countersunk area is produced in the area of the cutting edge on the workpiece.

[0160] As can be seen from the above description, the present invention provides a novel method for machining a workpiece, in which a rounding zone, a chamfer or a countersunk head zone can be produced in a simple, reliable and rapid manner on the cutting edge on the workpiece part side of the workpiece part still connected to the remaining workpiece or on the cutting edge on the workpiece part side formed by cutting off waste pieces from the workpiece. This makes it possible to dispense with the mechanical reprocessing of the cut-off workpiece part, so that a workpiece part with a rounding zone, a chamfer zone or a countersunk head zone can be manufactured more simply, more rapidly and at a more favorable cost. The implementation of the method according to the invention in an already existing laser beam machining device can be achieved in a simple manner without the need for elaborate technical measures, but rather by intervening in the machine control device to achieve the desired laser beam machining of the workpiece by means of the method according to the invention.

[0161] List of Reference Numerals

[0162] 1 Laser machining device

[0163] 2 Laser cutting device

[0164] 3 Cutting head

[0165] 4 Workbench

[0166] 5 Workpiece support

[0167] 6 Cross beam

[0168] 7 Guide slider

[0169] 8 Laser beam source

[0170] 9 Workpiece

[0171] 10 Remaining workpiece

[0172] 11 Workpiece part

[0173] 12 Control device

[0174] 13 Cutting nozzle

[0175] 14 Cutting line

[0176] 14-1, 14-2, 14-3, 14-4, 14-5 Sections of the cutting line

[0177] 15 Cutting gap

[0178] 15-1, 15-2, 15-3, 15-4, 15-5 Sections of the cutting gap

[0179] 16 Laser beam

[0180] 17 Upper workpiece surface

[0181] 18 Reprocessing line

[0182] 19, 19‘ Cutting edges

[0183] 20 Lower workpiece surface

[0184] 21 Chamfer or countersink area

[0185] 22 Reprocessing area

[0186] 22-1, 22-2, 22-3, 22-4, 22-4‘ Sections of the reprocessing area

[0187] 23 Tab

[0188] 24 Circle

[0189] 25 Process gas

[0190] 26 Machining beam

[0191] 27 Beam axis

[0192] 28 (Pre-drilled) hole

[0193] 29 Final hole

[0194] 30 Upper (pre-drilled) hole cutting edge

[0195] 31 Lower (pre-drilled) hole cutting edge

[0196] 32 (Pre-drilled hole) cutting line

[0197] 33 Nozzle tip

[0198] 34 Rounding area

[0199] 35 Upper side of the workpiece

[0200] 36 Lower side of the workpiece

[0201] 37 Burr

[0202] 38 (Pre-drilled) hole wall

[0203] 39 Final hole wall

[0204] 40 Upper final hole cutting edge

[0205] 41 Lower final hole cutting edge

[0206] 42 Outer chamfer or countersink head edge

[0207] 43 Inner chamfer or countersink head edge

[0208] 44 Chamfer or countersink head generation line

[0209] 45 Side

[0210] 46 Central axis

Claims

1. A method for machining a plate-shaped or tubular workpiece (9) by means of a machining beam (26) comprising a laser beam (16) and a process gas (25), wherein, for machining the workpiece (9), the machining beam is directed at the workpiece surface, In a first processing step, the workpiece (9) is processed with a first processing beam guided along a cutting line, thereby producing a cutting gap (15) on the workpiece (9) that passes through the thickness of the workpiece, the cutting gap extending in its length along the cutting line and being delimited in its width by two cutting edges in the workpiece (9), and wherein in a second processing step, the workpiece (9) is processed with a second processing beam, which is guided along a further processing line or further processing zone that extends parallel to one of the two cutting edges and offset therefrom, thereby producing a rounded area (34), a chamfered area or a countersunk area on the workpiece (9) in the region of the cutting edge, It is characterized in that The first processing jet comprises a process gas (25) of a different type than the second processing jet, wherein firstly a hole-shaped slot is cut out of the workpiece by means of the first processing step, wherein a pre-made hole is produced, which is a through hole, wherein the cut edge on the workpiece part side is subsequently processed by means of the second processing step in order to produce a rounded area, a chamfered area or a countersunk area on the cut edge on the workpiece part side, wherein the pre-made hole is subsequently enlarged to produce a final hole, wherein the chamfered area or the countersunk area and the pre-made hole are actively cooled by a gaseous or liquid cooling medium in terms of time after the production of the chamfered area or the countersunk area and before the pre-made hole is widened to produce the final hole, wherein the process gas (25) of the first processing jet comprises nitrogen or oxygen or a mixture of nitrogen and oxygen as an essential component, and the process gas of the second processing jet comprises nitrogen or oxygen or a mixture of nitrogen and oxygen as an essential component.

2. The method according to claim 1, wherein The workpiece (9) contains steel or contains aluminum or consists of them.

3. The method according to claim 1, characterized in that, The workpiece has a thickness in the range of 3 mm to 60 mm.

4. The method according to any one of claims 1 to 3, characterized in that i) for a workpiece (9) made of structural steel, the process gas of the second machining jet contains oxygen as an essential component; or ii) For workpieces (9) made of stainless steel or aluminum, the process gas of the second processing jet contains nitrogen as an essential component.

5. The method according to any one of claims 1 to 3, characterized in that The gas pressure of the process gas (25) in the second process jet is changed compared to the gas pressure of the process gas (25) in the first process jet.

6. The method according to any one of claims 1 to 3, characterized in that, The process gas of the second process jet is subjected to a lower gas pressure than the process gas (25) of the first process jet.

7. The method according to claim 6, characterized in that The process gas of the second processing jet is acted upon with a gas pressure of less than 7 bar.

8. The method according to claim 7, characterized in that i) the process gas of the second processing jet contains oxygen as an essential component and is subjected to a gas pressure in the range of 2 bar to 4 bar; or ii) The process gas of the second processing jet contains nitrogen as an essential component and is subjected to a gas pressure in the range of 0.3 bar to 1 bar.

9. The method according to any one of claims 1 to 3, characterized in that, The first machining beam is always oriented perpendicularly to the workpiece surface in the first machining step and the second machining beam is always oriented perpendicularly to the workpiece surface in the second machining step.

10. The method according to any one of claims 1 to 3, characterized in that, The laser power of the laser beam in the second machining beam is changed compared to the laser power of the laser beam (16) in the first machining beam.

11. The method according to claim 1, wherein The laser power of the laser beam in the second machining beam is less than the laser power of the laser beam (16) in the first machining beam.

12. The method according to claim 11, wherein The laser power of the laser beam in the second machining beam is at most 4 kW.

13. The method according to claim 11 or 12, characterized in that, The laser power of the laser beam (16) in the first machining beam is in the range of 1 kW to 40 kW, while the laser power of the laser beam in the second machining beam is in the range of 0.5 kW to 4 kW.

14. The method according to any one of claims 1 to 3, characterized in that The cutting nozzle (13) has a nozzle diameter, wherein the same nozzle diameter is used for the first and second machining beams.

15. The method according to any one of claims 1 to 3, characterized in that In order to produce the cutting gap (15), the first machining beam is guided along the cutting line only once; and In order to produce the rounded area (34), chamfered area or counterbored area, the second machining beam is guided along the reworking line or reworking area multiple times.

16. The method according to claim 15, characterized in that, The laser power of the laser beam in the second machining beam is smaller in the last pass along the reworking line or reworking area than in at least one previous pass along the reworking line or reworking area.

17. The method according to any one of claims 1 to 3, characterized in that, The first machining beam forms a smaller beam diameter on the workpiece surface than the second machining beam.

18. The method according to claim 17, wherein The beam diameter of the first machining beam on the workpiece surface is less than 50%, 40%, 30%, 20%, 10% or 1% of the beam diameter of the second machining beam on the workpiece surface.

19. The method according to any one of claims 1 to 3, characterized in that The machining beam is guided by the cutting nozzle (13) before reaching the workpiece surface, wherein the cutting nozzle (13) has a smaller spacing from the workpiece surface in the first machining step than in the second machining step.

20. The method according to claim 19, wherein The spacing of the cutting nozzle (13) from the workpiece surface is at most 5 mm in the first machining step and at least 15 mm in the second machining step.

21. The method according to any one of claims 1 to 3, characterized in that, The energy input per unit area and unit time into the workpiece (9) is greater in the first machining step than in the second machining step.

22. The method according to any one of claims 1 to 3, characterized in that, The rounded area (34), chamfered area or counterbored area directly abuts on or transitions into the cutting edge.

23. The method according to claim 1, wherein The diameter of the hole-shaped notch is equal to or less than the workpiece thickness of the workpiece (9).

24. The method according to claim 2, characterized in that, The steel is structural steel or stainless steel.

25. The method according to claim 5, wherein The gas pressure of the process gas in the second machining beam is changed compared to the process gas (25) in the first machining beam according to the material thickness of the workpiece (9) and / or the design dimensions of the rounded area, chamfered area or counterbored area.

26. The method according to claim 10, wherein The laser power of the laser beam in the second machining beam is changed compared to the laser beam (16) in the first machining beam according to the material thickness of the workpiece (9) and / or the design dimensions of the rounded area, chamfered area or counterbored area.

27. The method according to claim 14, characterized in that, The same cutting nozzle (13) is used for the first and second machining beams.

28. The method according to claim 16, wherein The laser power of the laser beam in the second machining beam is reduced by half of the laser power in the last pass along the reworking line or reworking area compared to at least one previous pass along the reworking line or reworking area.

29. The method according to claim 20, wherein The distance between the cutting nozzle (13) and the workpiece surface is at most 5 mm in the first machining step and at least 30 mm in the second machining step.

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