METHOD FOR MACHINING A PLATE- OR TUBE-SHAPED WORKPIECE

Description

[0001] The invention lies in the technical field of manufacturing metallic workpiece parts and relates to a method for processing a plate- or tube-shaped workpiece with a processing jet, in which a separating processing of the workpiece is carried out to create a cutting gap and a non-separating and at the same time non-joining modification of the workpiece is carried out to create a rounding zone, chamfer zone or countersink zone (see for example WO 2022 / 037797, which forms the basis for the preamble of claim 1).

[0002] Commercially available laser cutting devices enable the automated production of workpiece parts in large quantities and with high precision. In this process, workpiece parts are cut from a metallic workpiece using a laser beam along cutting lines that correspond to the contours of the workpiece parts. Additionally, by moving the laser beam along circular cutting lines, holes—that is, small-diameter cutouts—can be created in the workpiece parts at high speed.

[0003] Depending on the intended use of the cut-out workpiece parts, they may require extensive mechanical post-processing. For example, sharp cut edges may need to be rounded or chamfered or countersunk. Holes intended for countersunk screws are typically machined with a drill to create chamfers or countersinks to accommodate the screw heads.

[0004] In general, downstream mechanical processing is very time-consuming and often requires significant personnel resources, especially since it is frequently done manually. Furthermore, such post-processing is costly, undesirably lengthening and increasing the cost of manufacturing workpieces. This is particularly true for machining holes to create chamfers or countersinks, which is very time-consuming.

[0005] In contrast, the object of the present invention is to further develop conventional methods in which a plate- or tube-shaped workpiece is processed by means of a processing jet in such a way that the production of workpiece parts with rounded cut edges, chamfers or countersinks on cut edges can be carried out in an automated manner faster, more cost-effectively and with high quality.

[0006] This task is solved by a method for processing a plate- or tube-shaped workpiece using a processing beam comprising a laser beam and a process gas for ejecting molten workpiece material.

[0007] For the purposes of the present invention, the term "workpiece" refers to a plate- or tube-shaped, typically metallic component from which at least one workpiece part (good part) is to be produced. The plate-shaped workpiece is typically flat. Preferably, the workpiece contains or consists of steel, in particular structural steel or stainless steel, or aluminum. For example, the workpiece contains or consists of unalloyed structural steel. Preferably, this is unalloyed structural steel S235, S275, S355, S460, S185, S295, E355, E360, and particularly preferably S235, as it is commercially available (e.g., from ESB European Steel Business Group). Chromium-nickel steel is particularly preferred as the material for the workpiece. Preferably, the workpiece has a material thickness of 3 mm to 60 mm.

[0008] The processing beam is guided by a beam head and exits at a terminal cutting nozzle. As is typical, the laser beam is a focused, rotationally symmetric beam cone with a central beam axis (axis of symmetry). The beam diameter characterizes the transverse extent of the beam or its physical size perpendicular to the direction of propagation. During focusing, the laser beam is bundled by a focusing lens or a focusing mirror. The focus of the laser beam is defined by the point where the laser beam has its smallest cross-section or smallest beam diameter. The focal length indicates the distance from the principal plane of the lens (or mirror) to the focal point of an ideal, focused parallel beam. The shorter the focal length, the more tightly the laser beam is focused and the smaller the focus diameter, and vice versa.

[0009] The beam head also serves to guide the process gas, which is typically, but not necessarily, emitted from the same cutting nozzle and is preferably guided coaxially to the laser beam. The process gas is typically, but not necessarily, in the form of a gas cone that impacts the workpiece.

[0010] The workpiece rests on a workpiece support with its underside facing down. The workpiece has a (top) surface on its upper side. For a plate-shaped workpiece, this surface is flat. Unless otherwise specified, the term "workpiece surface" here and in the following text refers to the upper surface of the workpiece upon which the machining beam strikes. The opposite workpiece surface, where the workpiece typically rests on a support, is the workpiece underside.

[0011] The cutting head for guiding the laser beam and process gas can be moved relative to the workpiece in a typically horizontal plane parallel to the plane of the workpiece surface, as well as in a direction perpendicular to this, typically vertical.

[0012] In the present description of the invention, the reference system is always stationary relative to the workpiece, so that the cutting head is considered to be moving and the workpiece stationary. Locally, however, it is irrelevant whether the cutting head or the workpiece, or both, are moving. Therefore, it would be equally possible for the workpiece to be moved as an alternative to the moving cutting head, or for both the cutting head and the workpiece to be moved.

[0013] The energy of the laser beam depends on the specific design of the laser source and is typically specified in joules (J). The power of the laser beam (i.e., energy per unit time), typically measured in joules per second (J / s) or watts (W), describes the optical output power of a continuous-wave (CW) laser or the average power of a pulsed laser. Pulsed lasers are also characterized by their pulse energy, which is directly proportional to the average power and inversely proportional to the laser's repetition rate. "Energy density" refers to the energy of the laser beam per unit area of ​​the workpiece. Energy density is measured, for example, in J / mm².

[0014] Besides energy density, the traverse speed of the cutting head or laser beam is crucial for processing the workpiece; that is, the time a specific area of ​​the workpiece is irradiated by the laser beam. The term "displacement energy" is commonly used for this. This is the power of the laser beam absorbed by the workpiece per unit speed of the cutting head or processing beam, e.g., measured in watts per millimeter per second (mm / s). If the power of the laser beam is given in watts (W) as joules per second (J / s), then the displacement energy is accordingly measured in J / mm.

[0015] During processing, the linear energy of the laser beam is therefore crucial, with the energy absorbed by the workpiece depending on the energy density. For a given laser beam power, the energy absorbed by the workpiece depends on the size of the beam spot on the workpiece, corresponding to the beam diameter at the point where the laser beam strikes the workpiece surface. The beam diameter of the laser beam on the workpiece surface is determined by the focus position, i.e., the position of the laser beam's focus relative to the workpiece (perpendicular shortest distance), specifically relative to the workpiece surface toward which the laser beam is directed, or relative to the workpiece support.If the workpiece is located in the divergent region of the beam cone (focus above the workpiece surface onto which the laser beam strikes), increasing the distance between the focus and the workpiece increases the beam diameter on the workpiece, and vice versa. Thus, by changing the beam diameter on the workpiece through a change in focus position, the energy density of the laser beam, and therefore the energy absorbed by the workpiece (which contributes to the linear energy), can be precisely altered. The larger the beam diameter, the lower the energy absorbed by the workpiece, and vice versa. With a laser, the beam intensity outside the focus, relative to the cross-section, is not constant. Ideally, the power intensity follows a Gaussian profile. In any case, the energy density is relatively low towards the edges, especially outside the focus.

[0016] The linear energy also depends on the speed of the laser beam, i.e., the traverse speed of the cutting head or nozzle, also known as the "feed rate." The higher the feed rate, the shorter the time a given area of ​​the workpiece is irradiated, and vice versa. Thus, increasing the feed rate reduces the linear energy of the laser beam, and vice versa. It goes without saying that the energy density, and therefore the linear energy, can be changed by altering the power of the laser beam itself. The energy transferred to the workpiece can also be changed by altering the type and / or composition of the process gas used during processing.

[0017] According to the invention, the plate- or tube-shaped workpiece is processed in a two-step process by means of a processing beam (i.e., laser beam and process gas) directed onto the workpiece surface. In a first processing step, the workpiece is processed with a first processing beam guided along a cutting line, thereby creating a cutting gap in the workpiece that extends through the thickness of the workpiece, runs along the cutting line in length, and is limited in width by two cutting edges in the workpiece. In a second processing step, the workpiece is processed with a second processing beam guided along a post-processing line or zone that runs parallel and offset from one of the two cutting edges, thereby creating a rounding zone, chamfer zone, or countersink zone in the region of this cutting edge on the workpiece.For ease of reference and differentiation, the processing beam used in the first processing step is referred to as the "first processing beam," and the processing beam used in the second processing step is referred to as the "second processing beam." The laser beam interacts with the process gas directed at the cutting edge.

[0018] The method according to the invention thus comprises two process steps. In the first processing step, the first processing beam is used in cutting mode; in the second processing step, the second processing beam is used in non-cutting mode. In cutting mode, the linear energy of the laser beam on the workpiece, or the energy introduced into the workpiece, is so high that the processing beam cuts (separates) the workpiece, penetrating it to create a kerf. In non-cutting mode, the linear energy of the laser beam on the workpiece, or the energy introduced into the workpiece, is so low that the workpiece is processed non-cutting (non-separating), so that the workpiece is not penetrated, thereby creating a rounded, chamfered, or countersunk zone.

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

[0020] The process gas used in laser processing serves to expel the molten workpiece material or melt through the cutting gap. When creating a rounding, chamfering, or countersinking zone, it is also necessary to apply not only the laser beam but also the process gas to the workpiece in order to remove the resulting melt or slag.

[0021] In the method according to the invention, the first processing beam forms a smaller beam diameter on the workpiece surface than the second processing beam. This allows the processing beam to be used easily and quickly in cutting mode to create the cutting gap or in non-cutting mode to create a chamfer or rounding.

[0022] According to the invention, the beam diameter of the first processing beam on the workpiece surface is less than 50% of the beam diameter of the second processing beam on the workpiece surface. In currently common laser cutting machines, the beam diameter on the workpiece during the cutting process is typically 1 / 10 to 5 / 10 mm. To create a rounding, chamfering, or countersinking zone with a processing beam, the beam diameter on the workpiece is preferably at least 1.5 mm and is, for example, in the range of 3 to 25 mm.

[0023] According to one embodiment of the inventive method, the processing beam is guided through a cutting nozzle before impacting the workpiece surface, the cutting nozzle being closer to the workpiece surface during the first processing step than during the second. Preferably, the beam diameter on the workpiece is changed by altering the perpendicular distance of the cutting nozzle from the workpiece surface. It is particularly advantageous to change the beam diameter on the workpiece solely by altering the perpendicular distance of the cutting nozzle from the workpiece surface. According to the invention, the distance of the cutting nozzle to the workpiece surface is a maximum of 5 mm during the first processing step and at least 15 mm, and particularly at least 30 mm, during the second processing step. Advantageously, in the second processing step, the focus of the laser beam lies on or above the workpiece surface.Preferably, the focus position of the laser beam relative to the workpiece is changed by changing the height of the cutting head or cutting nozzle above the workpiece, i.e., the cutting head is typically moved in a vertical direction with a movement component perpendicular to the workpiece surface.

[0024] According to an advantageous embodiment of the method according to the invention, the processing beam is guided through a cutting nozzle before impacting the workpiece surface, wherein a focus of the laser beam of the second processing beam lies within the cutting nozzle, particularly in the range of 3 to 5 mm above a nozzle opening from which the laser beam exits. If the process gas of the first processing beam contains oxygen as a major component, it is advantageous for a focus of the laser beam of the first processing beam to lie within the cutting nozzle, particularly in the range of 1 to 6 mm above the nozzle opening. If the process gas of the first processing beam contains nitrogen as a major component, it is advantageous for a focus of the laser beam of the first processing beam to lie outside the cutting nozzle, particularly in the range of 0 to 10 mm below the nozzle opening.These measures allow the cutting gap and the rounding, chamfering or countersinking zone to be produced efficiently and with high accuracy.

[0025] According to an advantageous embodiment of the method according to the invention, the processing beam is guided through a cutting nozzle before striking the workpiece surface, with a focus of the laser beam of the second processing beam located in the range of 30 to 40 mm above the workpiece surface. If the process gas of the first processing beam contains oxygen as a major component, it is advantageous if a focus of the laser beam of the first processing beam is located in the range of 2 to 7 mm above the workpiece surface. If the process gas of the first processing beam contains nitrogen as a major component, it is advantageous if a focus of the laser beam of the first processing beam is located on the workpiece surface or in the workpiece, in particular 0 to 8 mm below the workpiece surface.These measures allow the cutting gap and the rounding, chamfering or countersinking zone to be produced efficiently and with high accuracy.

[0026] According to an advantageous embodiment of the method according to the invention, the first processing jet comprises a different process gas than the second processing jet. For the purposes of the present invention, a different process gas is present, in particular, if the process gas in the first processing jet and the process gas in the second processing jet differ in the type and / or composition of the gases used and / or in the gas pressure. This measure allows for a number of important advantages, including, in particular, the use of the processing jet in cutting or non-cutting mode for processing the workpiece.

[0027] In an advantageous embodiment of the process according to the invention, the process gas of the first processing jet comprises as a significant component (main component) nitrogen (N₂) or oxygen (O₂), or a mixed gas of nitrogen (N₂) and oxygen (O₂), wherein in the latter case, the mixed gas itself constitutes the main component of the process gas. The process gas of the second processing jet comprises as a significant component (main component) oxygen (O₂) or nitrogen (N₂), or a mixed gas of nitrogen (N₂) and oxygen (O₂), wherein in the latter case, the mixed gas itself constitutes the main component of the process gas. Preferably, the process gas of the first processing jet comprises as a significant component either oxygen or nitrogen. Preferably, the process gas of the second processing jet comprises as a significant component either oxygen or nitrogen.For example, the process gas of the first processing jet contains nitrogen as a major component, and the process gas of the second processing jet contains oxygen as a major component.

[0028] For the purposes of the present invention, a "substantial component" is understood to be a proportion of the respective gas in the process gas of more than 50%, in particular more than 75%, or even more than 90%. The process gas can, in particular, consist entirely of the respective gas that constitutes the main component. This applies analogously if the main component is a mixture of oxygen and nitrogen.

[0029] For machining a workpiece made of structural steel, it is particularly advantageous to use oxygen as a key component of the process gas in the second machining jet. This allows the molten metal formed to be completely oxidized in the cutting gap and thus easily removed from the workpiece. The process gas in the first machining jet can consist primarily of oxygen or nitrogen, or a mixture of oxygen and nitrogen. Preferably, the process gas in the first machining jet consists primarily of oxygen or nitrogen.

[0030] When machining a workpiece made of stainless steel or aluminum, nitrogen is advantageously used as a major component of the process gas in the second machining jet. Nitrogen is an inert gas and readily available at low cost. The process gas in the first machining jet can consist primarily of oxygen, nitrogen, or a mixture of oxygen and nitrogen. Preferably, the process gas in the first machining jet consists primarily of nitrogen.

[0031] According to the invention, the gas pressure of the process gas in the second processing jet is varied relative to the gas pressure of the process gas in the first processing jet, particularly depending on the material thickness of the workpiece and / or the dimensions of the rounding, chamfering, or countersinking zone. According to the invention, the process gas of the second processing jet is pressurized to a lower pressure than the process gas of the first processing jet. This advantageously results in a less concentrated, "softer" effect of the process gas on the workpiece surface, thus preventing excessive material spatter on the workpiece surface. Preferably, the gas pressure of the process gas in the second processing jet is less than 7 bar, which ensures both good melt removal and reliable prevention of material spatter.The stated gas pressure (boiler pressure) applies inside the cutting head before the process gas exits the cutting nozzle.

[0032] According to the invention, when the process gas of the second processing jet contains oxygen as a major component, the process gas is pressurized to a gas pressure in the range of 2 bar to 4 bar. This gas pressure is particularly advantageous in combination with a cutting nozzle having a nozzle diameter of 0.8 mm to 1.4 mm. According to the invention, when the process gas of the second processing jet contains nitrogen as a major component, the process gas is pressurized to a gas pressure in the range of 0.3 bar to 1 bar. This gas pressure is particularly advantageous in combination with a cutting nozzle having a nozzle diameter of at least 2.7 mm, and in particular exactly 2.7 mm.

[0033] In the method according to the invention, the processing beam is used in cutting or non-cutting mode. It is advantageous if the laser power of the laser beam in the second processing beam is varied compared to the laser power of the laser beam in the first processing beam, particularly depending on the material thickness of the workpiece and / or the dimensions of the rounding, chamfering, or countersinking zone. The larger the dimensions of the rounding, chamfering, or countersinking zone, the greater the laser power typically is. Similarly, the greater the material thickness of the workpiece, the greater the laser power typically is.

[0034] Preferably, the laser power of the laser beam in the second processing beam is lower than in the first processing beam. It is particularly preferred that the laser power of the laser beam in the second processing beam is a maximum of 4 kW, and 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 and in the second processing beam in the range of 0.5 kW to 4 kW. This allows the laser beam energy to be precisely adjusted for use in 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 focus diameter of the laser beam is at least 150 µm and / or the feed rate is at least 1 m / min.The closer the laser beam's focus is to the workpiece, the larger the focus diameter should be in the second processing step. Preferably, the focus diameter is greater than 250 µm when the focus is located on the workpiece surface.

[0035] For example, the laser power of the first processing beam, using a process gas containing oxygen or nitrogen as a major component, ranges from 1 kW to 40 kW. For instance, with structural steel as the workpiece material and a sheet thickness of up to 12 mm, and oxygen as the process gas, the maximum laser power is 4 kW; for sheet thicknesses greater than 12 mm, the maximum is 10 kW. When using nitrogen as the process gas, the maximum laser power technically possible with the system can be employed.

[0036] In an advantageous embodiment of the method according to the invention, the processing jet is guided through a cutting nozzle with a nozzle diameter before impacting the workpiece surface, wherein the same nozzle diameter, preferably the same cutting nozzle, is used for the first and the second processing jet. This measure allows for a particularly simple process control. In addition, the costs for implementing the method according to the invention can be reduced.

[0037] According to an advantageous embodiment of the inventive method, to generate the cutting gap, the first processing jet is guided only once along the cutting line, and to generate the rounding, chamfering or countersinking zone, the second processing jet is guided several times along the post-processing line or The laser beam is guided along the post-processing line or zone. This enables both efficient generation of the cutting gap and reliable formation of the rounding, chamfering, or countersinking zone. Preferably, the laser power of the laser beam in the second processing beam during the final pass along the post-processing line or zone is lower than during at least one previous pass along the post-processing line or zone, and is reduced by approximately half the laser power. In general, the more passes of the cutting head or cutting nozzle are used, the less laser power is required.

[0038] The linear energy of the laser beam on the workpiece, or the energy introduced into the workpiece, can be changed by changing the energy or power of the laser beam and / or changing the feed rate of the cutting head and / or focusing / defocusing the laser beam, i.e., by changing the beam diameter on the workpiece surface, in particular by changing the focus position relative to the workpiece and / or by changing the process gas used during processing.

[0039] Preferably, the path energy of the laser beam on the workpiece is changed by changing the focus position relative to the workpiece, which is preferably achieved by changing the height of the cutting head above the workpiece surface facing the cutting head, i.e., the cutting head is typically moved in a vertical direction with a movement component perpendicular to the workpiece surface.

[0040] According to one embodiment of the inventive method, the first processing beam forms a smaller beam diameter on the workpiece surface than the second processing beam. Advantageously, the cutting nozzle is located closer to the workpiece surface during the first processing step than during the second processing step. According to the invention, the beam diameter of the first processing beam is less than 50% of the beam diameter of the second processing beam on the workpiece surface. In currently common laser cutting machines, the beam diameter on the workpiece during the cutting process is typically 0.1 to 0.5 mm. To create a rounding, chamfering, or countersinking zone with the processing beam, the beam diameter on the workpiece is preferably at least 1.5 mm and is, for example, in the range of 3 to 25 mm.

[0041] Preferably, the beam diameter on the workpiece is changed by altering the perpendicular distance of the cutting nozzle from the workpiece surface. It is particularly advantageous to change the beam diameter on the workpiece solely by altering the perpendicular distance of the cutting nozzle from the workpiece surface. According to the invention, the distance of the cutting nozzle to the workpiece surface is a maximum of 5 mm during the first processing step and at least 15 mm, and in particular at least 30 mm, during the second processing step. Advantageously, in the second processing step, the focus of the laser beam lies on or above the workpiece surface. Preferably, the focus position of the laser beam relative to the workpiece is changed by altering the height of the cutting head or cutting nozzle above the workpiece; that is, the cutting head is typically moved vertically with a movement component perpendicular to the workpiece surface.

[0042] According to an advantageous embodiment of the inventive method, the energy input into the workpiece per area and time is greater in the first processing step than in the second processing step.

[0043] According to an advantageous embodiment of the inventive method, a workpiece part (good part) is cut out of the workpiece by means of the first processing step, forming the workpiece part and a residual grid, wherein the outer contour of the workpiece part is defined by the cutting line. One of the two cutting edges is a workpiece part-side cutting edge and the other is a residual grid-side cutting edge. The workpiece part-side cutting edge is processed by means of the second processing step. This measure allows a workpiece part (good part) to be provided with a rounding, chamfering, or countersinking zone in a particularly simple and efficient manner by means of the processing beam.

[0044] It is particularly advantageous if, to form the cutting gap, the first processing jet is switched off and then switched on again at least once, and preferably several times, as it is guided along the workpiece surface, thereby forming several cutting line segments, so that a bridge is arranged between each pair of adjacent cutting line segments, through which the workpiece part and the remaining grid remain connected. The workpiece part connected to the remaining workpiece is still an integral part of the workpiece, and the connection is sufficiently rigid according to the present invention so that, advantageously, a change in the position of the partially cut-out workpiece part relative to the remaining workpiece does not occur during the production of the rounding, chamfering, or countersinking zone.Any change in position that may occur during this process is negligibly small and does not lead to any reasonably significant change in the result. For creating a rounded, chamfered, or countersunk zone on a workpiece part, it is advantageous if the workpiece part is connected to the rest of the workpiece, meaning that there is still workpiece material on both sides of the cutting gap. This way, the workpiece part is fixed in its position and cannot slip or tilt, allowing the laser beam to be positioned precisely at the cutting edge when creating the rounded, chamfered, or countersunk zone. Furthermore, the molten metal produced during the creation of the rounded, chamfered, or countersunk zone flows into the cutting gap and can be removed from there—especially when using oxygen as the process gas—more easily than from the top of the workpiece.

[0045] Accordingly, in this embodiment, the creation of a rounded, chamfered, or countersunk zone is only carried out as long as the workpiece part is connected to the remaining workpiece via one or more webs, in particular microjoints or nanojoints. For the purposes of the present invention, a "web" is understood to be a connection made of workpiece material extending along the cutting line between the workpiece part and the remaining workpiece, wherein the web interrupts the cutting gap. A "microjoint" is a web with a relatively small dimension along the cutting line, which, according to the invention, is preferably in the range of 1 / 10 mm to 2 mm, and particularly preferably in the range of 1 / 10 mm to 1 mm. In common usage, a microjoint has a height that corresponds to the height or thickness of the workpiece (i.e., dimension perpendicular to the workpiece surface).A "nanojoint" is a microjoint whose height is reduced relative to the thickness of the workpiece, wherein, according to the invention, the height of a nanojoint is preferably at most half the thickness of the workpiece. Microjoints and nanojoints are well known to those skilled in the art from the practical application of manufacturing sheet metal workpieces by laser processing and from patent literature, so that they need not be discussed in detail here. For the sake of completeness, reference is made, for example, to international patent application WO 2019025327 A2 with regard to nanojoints.

[0046] To remove the workpiece part from the rest of the workpiece, a closed cutting gap must be formed. According to this embodiment of the invention, the formation of a closed cutting gap is only provided after the rounding, chamfering, or countersinking zone has been created on the workpiece part's cutting edge. The creation of a closed cutting gap can be achieved using a machining beam in cutting mode, whereby one or more webs, in particular one or more microjoints or nanojoints, with which the workpiece part is still connected to the rest of the workpiece, are severed. The workpiece part is thereby cut free from the rest of the workpiece. According to one embodiment, the method according to the invention comprises a step in which the workpiece part is cut free from the rest of the workpiece using a machining beam in cutting mode.

[0047] The workpiece part can also be separated from the rest of the workpiece without a machining beam, whereby the one or more webs by which the workpiece part is still connected to the rest of the workpiece are mechanically severed. This can be achieved, for example, by machining or cutting (not by a machining beam) or simply by breaking the workpiece part out of the rest of the workpiece. Methods commonly used in the trade, particularly for cutting microjoints or nanojoints, are well known to those skilled in the art, so they need not be discussed in detail here. According to the invention, the invention thus also specifically includes the case where a single section of the cutting gap is produced by means of a machining beam, wherein the workpiece part is still connected to the rest of the workpiece by a single web, in particular a micro- or nanojoint, and this web is mechanically severed not by the machining beam, but in another way.According to one embodiment, the inventive method comprises a step in which the workpiece part is completely separated from the rest of the workpiece not by the machining beam, but by mechanically cutting one or more webs, in particular by machining or cutting (not machining beam) or by breaking off the workpiece part from the rest of the workpiece.

[0048] According to an advantageous embodiment of the inventive method, a hole-shaped recess is cut out of the workpiece by means of the first processing step, forming a waste piece and a workpiece part, wherein the outer contour of the waste piece and the inner contour of the hole-shaped recess in the workpiece part are defined by the cutting line. One of the two cutting edges is a workpiece-side cutting edge and the other is a waste-side cutting edge. The workpiece-side cutting edge is processed by means of the second processing step. Accordingly, the creation of a rounding, chamfering, or countersinking zone on the workpiece-side cutting edge of the workpiece part (i.e., the workpiece remaining after removal of the waste piece) is carried out when the waste piece has been cut out of the workpiece (i.e.,The waste portion has no connection between the workpiece material and the remaining workpiece. This measure allows a workpiece part (good part) to be provided with a rounding, chamfering, or countersinking zone in a particularly simple and efficient manner using the machining jet, after a waste portion has been cut away from the workpiece to create the workpiece part.

[0049] To cut out the waste part, the processing jet is guided in cutting mode along a circular, closed cutting line, thereby creating a circular, closed cutting gap. The waste part (blob) is cut out of the workpiece. However, it is also possible to split the blob with the processing jet. Removing the blob from the workpiece creates a circular hole (opening) in the workpiece. As a rule, the blob falls downwards due to its own weight, thus creating the hole in the workpiece. The hole is preferably created within the contour of a workpiece segment to be cut out. Advantageously, the hole-shaped recess has a diameter that is equal to or smaller than the workpiece thickness. As tests of the invention have shown, the inventive method can produce particularly small holes with chamfers or...Countersinks can be created without the risk of damaging an adjacent hole in the process. This would be possible when using a bevel cut to create a chamfer or countersink.

[0050] The cutting gap is generated along the contour of the workpiece part or scrap part; that is, the cutting gap always defines the contour of the workpiece part or scrap part. Accordingly, the term "cutting gap" as used in the present invention does not include sections of the cutting gap that are not contour-defining and do not extend along the contour of the workpiece part or scrap part. For example, the workpiece is often pierced away from the contour, and the machining jet is only moved a short distance towards the contour-defining cutting line.

[0051] In the inventive method, to create a rounding, chamfering, or countersinking zone on the workpiece in the area of ​​the cut edge, the workpiece is processed with a second machining beam, which is guided along a post-processing line or zone that runs parallel and offset to one of the two cut edges. According to one embodiment, the machining beam is always guided in a straight line along one of the two cut edges or parallel and offset to it. This enables particularly fast creation of the rounding, chamfering, or countersinking zone. According to a further embodiment, the machining beam can also be moved transversely to one of the two cut edges (secondary movement), as long as the primary movement is guided along one of the two cut edges or parallel and offset to it. The secondary movement is superimposed on the primary movement.In this case, the movement of the machining beam, in addition to motion components along one of the two cutting edges or parallel to it, also includes motion components perpendicular (i.e., perpendicular) to one of the two cutting edges, so that a larger area of ​​the workpiece is swept by the machining beam. For example, the machining beam performs a meandering back-and-forth movement along one of the two cutting edges or parallel to it. During its movement along one of the two cutting edges or parallel to it, the machining beam is repeatedly deflected laterally and then returned to it.

[0052] Advantageously, the laser beam axis is always perpendicular to the flat workpiece support in both the first and second processing steps, meaning the angle between the beam axis and the workpiece support is 90°. This offers advantages in terms of control technology. Furthermore, the costs associated with implementing a corresponding swivel function for the processing beam relative to the workpiece support can be saved. However, it is also conceivable that the beam axis is changed when irradiating the workpiece, whereby the beam axis assumes an angle other than 90° to the workpiece support, at least temporarily. The alignment of the laser beam can be achieved by swiveling the cutting head (mechanically) and / or swiveling the laser beam (optically).For example, by swiveling the laser beam during the creation of the rounding, chamfering or countersinking zone, a larger area of ​​the workpiece can be covered, which can be advantageous.

[0053] It is understood that the aforementioned embodiments of the invention can be used individually or in any combination without leaving the scope of the present invention. Brief description of the drawings

[0054] The invention will now be explained in more detail using exemplary embodiments, with reference to the accompanying figures. These show: Fig. 1 a schematic representation of an exemplary laser processing device for carrying out the method according to the invention; Fig. 2-16 Exemplary methods for machining a workpiece; Figs. 17-18 Exemplary methods for machining a workpiece; Figs. 19-22Examples of non-linear movement of the laser beam along the post-processing line; Figs. 23-27 Various designs to illustrate the creation of a rounding, chamfering or countersinking zone; Fig. 28A-28C an embodiment of the inventive method in which holes with countersinks or chamfers are produced; Fig. 29A-29D a further embodiment of the inventive method in which holes with countersinks or chamfers are produced; Fig. 30A-30B a schematic representation of the cutting head in different positions for separating or non-separating machining of the workpiece; Fig. 31 a flowchart of the method according to the invention. Detailed description of the drawings

[0055] First, be Figure 1Considered, in which a laser processing device known per se for laser cutting of plate-like workpieces is illustrated. The laser processing device, designated overall by reference numeral 1, comprises a laser cutting unit 2 with a cutting head 3, and a work table 4 with a flat workpiece support 5 for a workpiece 9 (not shown in Figure 1 , see e.g. Figures 2 to 16 ), for example, a flat sheet of metal.

[0056] The workpiece support 5 is spanned by a crossbeam 6, which is guided for movement along a first axis (x-direction). A guide carriage 7 for the cutting head 3 is mounted on the crossbeam 6 and is guided for movement along a second axis (y-direction) perpendicular to the first axis. The cutting head 3 can thus be moved in a plane defined by the two axes (x- and y-directions) parallel to and relative to, for example, the horizontal workpiece support 5. The cutting head 3 is also designed to be vertically movable in a third axis (z-direction), which is perpendicular to the first and second axes, thereby allowing the distance perpendicular to the workpiece support 5 or workpiece 9 to be changed. With a horizontal workpiece support 5, the z-direction corresponds to the direction of gravity.

[0057] The cutting head 3 has a cutting nozzle 13 on its side facing the workpiece support 5, which tapers conically towards the workpiece support 5. The cutting head 3 and the cutting nozzle 13 serve to guide a laser beam 16 together (see e.g. Figures 2 to 16 , 30A, 30B ) and a process gas 25 (see Figure 27 , 30A, 30B ).

[0058] The processing beam 26 for processing the workpiece 9 comprises the laser beam 16 and the process gas 25 (see Figure 27 , 30A, 30B The process gas 25 is discharged from the cutting nozzle 13 in the form of a gas cone and is guided coaxially to the laser beam 16. It is understood that the process gas 25 (i.e., the process gas jet in the form of a gas cone) is guided along with the laser beam 16.

[0059] The laser beam 16 is generated by a laser beam source 8 and guided, for example, through a beam guide tube and several deflecting mirrors or a fiber optic cable to the cutting head 3. The laser beam 16 can be focused onto the workpiece 9 using a focusing lens or adaptive optics. Because the cutting head 3 can be moved along the first axis (x-direction) and second axis (y-direction), the laser beam 16 can be directed to any point on the workpiece 9.

[0060] The workpiece 9 has two opposing workpiece surfaces 17, 20 (see e.g. Figure 23), wherein a first or upper workpiece surface 17 faces the cutting nozzle 13 and a second or lower workpiece surface 20 faces away from the cutting nozzle 13. The cutting head 3 can be moved vertically in the z-direction, thereby adjusting the distance between the cutting nozzle 13 and the workpiece 9. The distance of the cutting head 3 from the upper workpiece surface 17 can be adjusted before, during, and after laser processing. The focus position of the laser beam 16 can be adjusted by changing the distance of the cutting nozzle 13 from the upper workpiece surface 17 and / or via optical elements in the cutting head 3, for example, adaptive optics.

[0061] The process gas 25 serves to expel the molten material from the kerf. The process gas is generated by a gas jet generator (not shown). Inert process gases include, for example, helium (He), argon (Ar), or nitrogen (N₂). Oxygen (O₂) is typically used as the reactive process gas. The use of gas mixtures is also known. Within the cutting head 3, the process gas maintains a predetermined process gas pressure (boiler pressure), exits the cutting nozzle 13 at this pressure, and is guided coaxially to the laser beam 16 to the processing point.

[0062] As in Figure 1As shown, the flat workpiece support 5 consists, for example, of a multitude of support elements with, for example, triangularly shaped support point tips, which together define a support surface for the workpiece 9 to be processed. Here, the support elements are designed, for example, as elongated support ribs, each extending along the y-direction and arranged side by side in a parallel arrangement along the x-direction with, for example, a constant spacing. Not shown in detail is an extraction device through which cutting fumes, slag particles, and small waste pieces generated during laser cutting can be extracted.

[0063] A program-controlled control device 12 serves to control / regulate the inventive method for laser processing of the workpiece 9 in the laser processing device 1.

[0064] The following describes embodiments of the method of the present invention, in which a workpiece part 11 is cut out of the workpiece 9, wherein the workpiece 9 is modified at the workpiece part-side cutting edge of the workpiece part still connected to the remaining workpiece (i.e., residual workpiece) to produce a rounding, chamfering, or countersinking zone. In a first machining step, a section of a cutting gap is created, and in at least a second machining step, a rounding, chamfering, or countersinking zone is produced at the workpiece part-side cutting edge of the cutting gap by modifying the workpiece. Reference is made to the Figures 2 to 16 taken, which correspond in this order to later procedural situations.

[0065] First, be Figure 2The diagram shows a section line 14 (dashed). Section line 14 is an imaginary line corresponding to the contour of a workpiece part 11 to be produced from workpiece 9. The contour represents the outer shape of workpiece part 11. Workpiece part 11 is to be completely cut out of the flat or tube-shaped workpiece 9 (not shown in detail), leaving the remaining workpiece 10. Here, workpiece part 11 has, for example, a rectangular shape with rounded corners, although it is understood that workpiece part 11 can have any shape.

[0066] In Figure 3The laser beam 16 exiting the cutting head 3 is schematically illustrated. The laser beam 16 is guided along the cutting line 14, whereby, at a corresponding linear energy of the laser beam 16 on the workpiece 9, a cutting gap 15 is created in 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 intersects a cutting position A of the cutting line 14. As shown in Figure 3As illustrated, the cutting head 3 is moved along the cutting line 14, with the laser beam 16 moving from cutting position A to cutting position B. This creates a section 15-1 of the cutting gap 15 (solid line) that cuts through the workpiece 9 from cutting position A to cutting position B. The first section 15-1 of the cutting gap 15 is created in a first section 14-1 of the cutting line 14. The laser beam 16 can also penetrate the workpiece 9 at a distance from the cutting line 14, in which case the cutting gap 15, according to the present invention, extends only along the contour (i.e., cutting line 14) of the workpiece part 11.

[0067] In Figure 4Figure 1 illustrates a situation in which the first section 15-1 of the cutting gap 15, from cutting position A to cutting position B, has been completely produced. The separating machining of the workpiece 9 is now interrupted. The laser beam 16 is switched off and the cutting head 3 is moved to a post-processing position A' near cutting position A (see Figure 1). Figure 5 ). As in Figure 4 As illustrated by an arrow, the traverse movement of the cutting head 3, for example, occurs in a direct line between the cutting position B and the post-processing position A'. The post-processing position A' lies on a post-processing line 18 for generating a rounding zone 34 (see Figures 25 and 26 ) or chamfer or subsidence zone 21 (see Figure 23 ) as post-processing of the workpiece 9.

[0068] As in Figure 5 and the further Figures 6 to 16As shown, the post-processing line 18 is laterally offset and equidistant from the cutting line 14. During post-processing of the workpiece 9, the cutting head 3 is moved along the post-processing line 18. This movement can be linear or non-linear along the post-processing line 18, as explained in more detail below. Post-processing of the workpiece 9 takes place in a post-processing zone 22, which typically has a wider dimension perpendicular to its extent than the post-processing line 18 (not shown in the drawing). The post-processing zone 22 is the area of ​​the workpiece 9 that is modified by the laser irradiation. Corresponding to the post-processing line 18, the post-processing zone 22 also extends along the cutting line 14. The cutting gap 15 is bounded by two opposing cutting edges 19, 19' (see, for example, Figure 1). Figure 23 ).

[0069] As in Figure 5 As illustrated, the laser beam 16 is then switched on again and the cutting head 3 is moved along the post-processing line 18 (dashed line), whereby the laser beam 16 is moved from the first post-processing position A' to a second post-processing position B' near the cutting position B. Here, post-processing of the workpiece 9 takes place in a first section 22-1 of the post-processing zone 22.

[0070] In Figure 6 Figure 1 shows a situation in which 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 post-processing zone 22, is schematically illustrated with a solid line. Analogous to the section-by-section generation of the cutting gap 15, the post-processing zone 22 is also generated section by section.

[0071] As in Figure 6As illustrated, starting from cutting position B, the workpiece 9 is further machined by separating, whereby the already created first section 15-1 of the cutting gap 15 is extended to a cutting position C.

[0072] In Figure 7 Figure 1 illustrates a situation in which a further, or second, section 15-2 of the cutting gap 15 was created from cutting position B to cutting position C along a second section 14-2 of the cutting line 14. The separating machining of the workpiece 9 is now interrupted. The laser beam 16 is switched off, and the cutting head 3 is moved in a straight line to a position above the post-processing position B', as illustrated by an arrow.

[0073] As in Figure 8To illustrate, the laser beam 16 is now switched on again and the cutting head 3 is moved along the post-processing line 18, with the laser beam 16 being moved from the post-processing position B' to a post-processing position C' near the cutting position C.

[0074] In Figure 9 Figure 1 shows a situation in which the workpiece 9 was modified along the entire second section 15-2 of the cutting gap 15 between the post-processing position B' and the post-processing position C' in a further, or second, section 22-2 of the post-processing zone 22. The second section 22-2 of the post-processing zone 22 extends the previously generated first section 22-1 of the post-processing zone 22.

[0075] As in Figure 9As illustrated, starting from the cutting position C, the workpiece 9 is then further machined by separating, whereby the already created part of the cutting gap 15 is extended to a cutting position D.

[0076] In Figure 10 Figure 1 illustrates a situation in which a third section 15-3 of the cutting gap 15 is generated from cutting position C to cutting position D along a third section 14-3 of the cutting line 14. The separating machining of the workpiece 9 is now interrupted. The laser beam 16 is switched off, and the cutting head 3 is moved to a position above the post-processing position C' of the post-processing line 18 for the subsequent post-processing. The third section 15-3 of the cutting gap 15 extends the second section 15-2 of the cutting gap 15.

[0077] As in Figure 11To illustrate, the laser beam 16 is now switched on again and the cutting head 3 is moved along the post-processing line 18, with the laser beam 16 being moved from the post-processing position C' to a post-processing position D' near the cutting position D.

[0078] In Figure 12 Figure 1 shows a situation in which the workpiece 9 was modified along the entire third section 15-3 of the cutting gap 15 from post-processing position C' to post-processing position D' in a third section 22-3 of the post-processing zone 22. The third section 22-3 of the post-processing zone 22 extends the previously generated second section 22-2 of the post-processing zone 22.

[0079] As in Figure 12 As illustrated, starting from the cutting position D, the workpiece 9 is now further machined by separating, whereby the already created part of the cutting gap 15 is extended to a cutting position E.

[0080] In Figure 13 Figure 1 illustrates a situation in which a fourth section 15-4 of the cutting gap 15 was created from cutting position D to cutting position E along a fourth section 14-4 of the cutting line 14. The separating machining 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.

[0081] The laser beam 16 is now switched off and the cutting head 3 is moved to a position above the post-processing position D' of the post-processing line 18 for the following post-processing.

[0082] As in Figure 14 As illustrated, the laser beam 16 is switched on again and the cutting head 3 is moved along the post-processing line 18, with the laser beam 16 being moved from the post-processing position D' to a post-processing position E' near the cutting position E.

[0083] In Figure 15Figure 1 shows a situation in which the workpiece 9 was modified along the entire fourth section 15-4 of the cutting gap 15 from the post-processing position D' to the post-processing position E' in a fourth section 22-4 of the post-processing zone 22. The fourth section 22-4 of the post-processing zone 22 extends the previously generated third section 22-3 of the post-processing zone 22.

[0084] As in Figure 15As illustrated, starting from cutting position E, the workpiece 9 is further machined by separating the material. The already created portion of the cutting gap 15 is extended along a fifth section 14-5 of the cutting line 14 to cutting position A. This closes the cutting gap 15 and separates the workpiece part 11 from the remaining workpiece 10, allowing it to be removed. No further post-processing of the separated workpiece part 11 is performed, as the process does not involve any post-processing of the separated workpiece part 11. A fifth section 15-5 of the cutting gap 15 is created, which extends the fourth section 15-4 of the cutting gap 15.

[0085] In all cutting operations, the laser beam 16 has a line energy dimensioned such that the workpiece 9 is cut through; i.e., the laser beam 16 is in cutting mode. In all post-processing operations of the workpiece 9 to create a rounding, chamfering, or countersinking zone, the laser beam 16 has a line energy dimensioned such that the workpiece 9 is neither joined nor cut; i.e., the laser beam 16 is in non-cutting mode. The beam axis of the laser beam 16 is, for example, parallel to the conical cutting nozzle 13 and strikes the workpiece 9 perpendicularly. In all cutting operations as well as in all post-processing operations, the laser beam 16 is directed at the upper workpiece surface 17 with an unchanged perpendicular orientation of its beam axis relative to the upper workpiece surface 17.

[0086] The post-processing operations on workpiece 9 can be varied in many ways. For example, the post-processing positions could also be positioned such that workpiece 9 is modified only along a portion of the respective section 14-1 to 14-5 of the cutting line 14 or a portion of the respective section 15-1 to 15-5 of the cutting gap 15, i.e., the respective sections 22-1 to 22-4 of the post-processing zone 22 do not extend over the entire length of the associated sections 14-1 to 14-5 of the cutting line 14 or over the entire length of the associated sections 15-1 to 15-5 of the cutting gap 15. For example, the direction for generating the post-processing could also be opposite to the direction for generating the cutting gap 15.

[0087] As especially from Figure 16As can be seen, in the last (fifth) separation procedure, a section 15-5 of the cutting gap 15 is produced, the length of which is smaller than the respective lengths of the sections of the cutting gap 15 produced in all previous separation operations. This measure advantageously ensures that as little of the cutting gap 15 as possible remains unprocessed. It would also be possible for the lengths of the parts of the cutting gap 15 produced in the separation procedures to increase continuously, starting from the clearance point of the workpiece part 11.

[0088] With regard to complete post-processing of the workpiece part 11, the following embodiment of the method according to the invention is particularly advantageous. Here, after modifying the workpiece 9 in the fourth section 22-4 of the post-processing zone 22, but before generating the fifth section 15-5 of the cutting gap 15, i.e., before cutting free the workpiece part 11, post-processing of the workpiece 9 is carried out along a fifth section 14-5 of the cutting line 14 between the post-processing positions E' and A'. This is demonstrated by an insertion in Figure 15This is illustrated schematically. Here, the fourth section 22-4 of the post-processing zone 22 is extended to the post-processing position A'. The extended fourth section 22-4' of the post-processing zone 22 thus extends to the post-processing position A', so that the post-processing zone 22, as a closed, elongated area, extends completely over the entire contour of the workpiece part 11. In particular, with such post-processing, a chamfer zone can advantageously be created on one or both of the subsequently generated cutting edges of the cutting gap 15, also in the area of ​​the fifth section 14-5 of the cutting line 14. Subsequently, the workpiece part 11 is cut free by generating the fifth section 15-2 of the cutting gap 15.

[0089] It is understood that the number of sections 14-1 to 14-5 of the cutting line 14 or of sections 15-1 to 15-5 of the cutting gap 15 in the embodiments of the Figures 2 to 16This is an example and can be larger or smaller.

[0090] Based on the Figures 2 to 16 Exemplary embodiments of the process were described, wherein, in an alternating sequence, a separating machining of the workpiece 9 is performed first, followed by a post-machining of the workpiece 9. It would also be possible to first create different sections of the cutting gap 15, which are separated from each other by bridges, in particular microjoints or nanojoints, followed by a post-machining of the workpiece 9. This is illustrated by the Figures 17 and 18 illustrated.

[0091] As in Figure 17As shown, according to a further embodiment of the inventive method, three sections 15-1, 15-2, 15-3 of a cutting gap 15 are first generated, which are separated from each other by webs 23, here for example microjoints or nanojoints. To generate the sections 15-1, 15-2, 15-3 of the cutting gap 15, the laser beam 16 is inserted at a distance 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 gap 15 is created along a Figure 17 The cutting line 14, not shown in detail, is generated. It is understood that a larger 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.

[0092] As in Figure 18As illustrated, after the creation of sections 15-1, 15-2, and 15-3 of the cutting gap 15, the workpiece 9 undergoes post-processing to create a rounding zone 34 and a chamfer or countersink zone 21 at the workpiece-side cutting edge 19. The laser beam 16 is guided along a post-processing line 18. The post-processing line 18 is laterally offset and equidistant from the cutting line 14. In particular, the post-processing line 18 also extends over the areas of the cutting line 14 where a web 23 is located; that is, the workpiece 9 is also post-processed in the area of ​​the webs 23. As tests have shown, with sufficiently small web dimensions 23, adequate post-processing of the workpiece 9 can be achieved, as this only minimally affects the gas dynamics of the process gas.

[0093] After post-processing of the workpiece 9 to create a rounded zone 34, chamfered or countersunk zone 21, the webs 23 are cut, for example by means of the laser beam 16 or manually, and the workpiece part 11 is removed from the remaining workpiece 10. It is also conceivable that the webs 23 are cut during the post-processing of the workpiece 9 in the area of ​​the webs 23, so that the workpiece part 11 is simultaneously cut free by the post-processing. This can be the case in particular if the webs 23 are designed as nanojoints with a reduced height.

[0094] During the creation of 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 post-processing of the workpiece 9, the laser beam 16 is guided in a straight line or non-straight line along the post-processing line 18. In particular, during the post-processing of the workpiece 9, the laser beam 16 can also have movement components transverse (perpendicular) to the post-processing line 18, whereby a secondary movement is superimposed on a primary movement. This can be seen from the Figures 19 to 22 illustrated.

[0095] In the Figures 19 to 22Several exemplary configurations of the laser beam 16 along the post-processing line 18 are shown. For the sake of simplicity, it is assumed that the post-processing line 18 extends horizontally from left to right. The movement of the laser beam 16 along the post-processing line 18 corresponds to the primary movement, to which a secondary movement with movement components perpendicular to the post-processing line 18 is superimposed.

[0096] In Figure 19Figure 1 illustrates a variant in which the laser beam 16 is guided along closed circles 24 (i.e., closed path segments of the laser beam 16) arranged in a row along the post-processing line 18. After traversing each circle 24, the laser beam 16 moves a short distance in a straight line along the post-processing line 18 and is then guided along the next circle 24. The circles 24 overlap in the direction of the post-processing line 18. Instead of circles, the laser beam 16 could also be guided along ellipses. The movement of the laser beam 16 thus has linear motion components along the post-processing line 18 and components perpendicular to the post-processing line 18. The post-processing zone 22, which results from the area of ​​the workpiece 9 swept over by the laser beam 16, can be made relatively wide by this measure, particularly for producing deep and / or wide chamfers or bevels.Subsidence zones.

[0097] In the Figures 20 to 22 Variants are illustrated in which the laser beam 16 is guided in a meandering pattern with back-and-forth movements along the post-processing line 18. Here, too, the movement of the laser beam 16 includes movement components perpendicular to the post-processing line 18. Figure 20 The meandering movement of the laser beam 16 is rectangular, in Figure 21 triangular (sawtooth-shaped) and in Figure 22The laser beam 16 is sinusoidally shaped. This is only an example; other meandering movements of the laser beam 16 are equally possible. In principle, according to the invention, any meandering back-and-forth movement of the laser beam 16 extending along the post-processing line 18 is possible and provided for. A relatively wide post-processing zone 22 can also be generated by the meandering movement of the laser beam 16, particularly for producing especially deep and / or wide chamfer or countersink zones.

[0098] In the Figures 23 and 24 Figure 21 illustrates the creation of a chamfer or subsidence zone. Figure 24 Figure 1 shows, using a perspective view, how the cutting head 3 or laser beam 16 is guided along the cutting gap 15 to create a chamfer or countersink zone 21. As shown in the cross-sectional view of Figure 23(Cut perpendicular to the plane of the workpiece 9) clearly visible, during the post-processing of the workpiece 9, the workpiece-side cut edge 19 adjacent to the upper workpiece surface 17 is provided with the chamfer or countersink zone 21 by the laser beam 16. The post-processing line 18 is laterally offset (e.g., equidistant) relative to the cutting line 14, which in Figures 23 and 24The chamfer or countersink zone 21 is not shown. Here, the creation of the chamfer or countersink zone 21 is achieved, for example, through several steps or post-processing operations carried out on the same section of the cutting gap 15. In the first post-processing operation, the workpiece part 11 is irradiated in an area containing the workpiece-side cutting edge 19. The post-processing line 18 is laterally offset (e.g., equidistantly) relative to the cutting line 14 in the direction of the workpiece part 11. This can be repeated one or more times, if necessary, to form the chamfer or countersink zone 21 further away from the workpiece-side cutting edge 19. In this case, the workpiece-side cutting edge 19 is no longer irradiated.It would also be conceivable to first irradiate the workpiece part 11 in such a way that an area not containing the workpiece-side cutting edge 19 is irradiated, followed by a continuous offset of the post-processing line 18 in the direction of the cutting gap 15, whereby the workpiece-side cutting edge 19 is finally also irradiated. During the post-processing of the workpiece 9 to create the chamfer or countersink zone 21, the workpiece-side cutting edge 19 is irradiated in at least one of the post-processing steps.

[0099] The laser beam 16 is particularly advantageous when generating the chamfer or sinking zone 21 by moving it meanderingly along the cutting line 14 or along a series of circles or ellipses, as shown by the Figures 19 to 22 This illustrates how the width and / or depth of the chamfer or subsidence zone 21 can be significantly increased.

[0100] In the Figures 25 and 26The creation of a rounded zone 34 at the workpiece-side cutting edge 19 of the workpiece part 11 is explained in more detail. Figure 25 During the post-processing of the workpiece 9, the workpiece-side cut edge 19 of the workpiece part 11 adjacent to the workpiece surface 17 of the workpiece top 35 is rounded by remelting using the laser beam 16, thereby creating a rounded zone 34. The post-processing line 18 is arranged laterally (e.g., equidistantly) relative to the cutting line 14, preferably if the maximum distance between the post-processing line 18 and the cutting line 14 is half the cutting gap width of the cutting gap 15 plus the radius of the beam cone of the laser beam 16 at the workpiece surface 17. This is in Figure 25 not shown. In Figure 26During the post-processing of workpiece 9, the laser beam 16 simultaneously rounds the workpiece-side cutting edge 19 adjacent to the workpiece surface 20 on the underside 36 of the workpiece, thereby creating a rounding zone 34, and smooths the remaining workpiece-side cutting edge 19' adjacent to the workpiece surface 17. The post-processing line 18 is laterally offset (e.g., equidistant) relative to the cutting line 14, which in Figure 26 not shown.

[0101] In Figure 27The creation of a chamfer or countersink zone 21 or a rounding zone 34 on the workpiece-side cutting edge 19 along the cutting gap 15 is schematically illustrated in a sectional view perpendicular to the plane of the workpiece 9. The traverse movement of the laser processing head 3 along the cutting gap 15 or along the workpiece-side cutting edge 19 is indicated by an arrow. The processing beam 26 comprises the laser beam 16 and the process gas 25. The melt generated during the creation of the chamfer or countersink zone 21 or rounding zone 34 is driven through the cutting gap 15 by the process gas 25.

[0102] The based on the Figures 28A to 28CThe embodiments of the method according to the invention illustrated in Figures 29A to 29D can be carried out in two steps or optionally in three steps, wherein holes, each with a chamfer or countersink zone, are produced in the workpiece. The workpiece part is a region of the remaining workpiece (remaining workpiece) and is intended to be cut out of the workpiece after one or more holes, each provided with a chamfer or countersink zone, have been produced. The holes with their respective chamfer or countersink zones are typically formed in a workpiece part to be cut out of the workpiece.

[0103] In the two-step variant, a hole-shaped recess is first cut out of the workpiece, creating a waste piece and a workpiece part. The outer contour of the waste piece and the inner contour of the hole-shaped recess in the workpiece part are defined by the cutting line, with one of the two cutting edges being a workpiece-side cutting edge and the other being a waste-piece-side cutting edge. The workpiece-side cutting edge is then machined to create a chamfer or countersink. In the three-step variant, a hole-shaped recess is first cut out of the workpiece, creating a pilot hole. The waste piece and a workpiece part are then machined to create a chamfer or countersink.The pilot hole is then widened to create a final hole.

[0104] For ease of reference, the hole created in the workpiece in the first step is referred to as a "hole" or "pre-hole," depending on whether the production of the holes, each with a chamfer or countersink, is carried out in two or three steps. Only when three steps are performed does the hole constitute a pre-hole, from which a final hole is created by widening. The term "(pre-)hole" can therefore refer to the process in two or three steps. Accordingly, the term "pre-hole cutting line" is used for the cutting line used to create the pre-hole, and the term "final hole cutting line" is used for the cutting line used to create the final hole. The terms "pre-hole" and "final hole," used for the production of countersunk holes in three steps, serve only to distinguish between different phases of the process for producing a hole with a chamfer or countersink.Countersinking zone, where the final hole results from a widening of the pilot hole. The finished hole is produced by creating the final hole within the chamfer or countersink.

[0105] Reference will now be made to the Figures 28A to 28C as well as 29A to 29D, wherein exemplary embodiments of the inventive method for laser beam processing of a workpiece 9 by the beam device 1 of Figure 1 The following are illustrated. For the purpose of a simplified representation and as sufficient for understanding the invention, only the cutting nozzle 13, the laser beam 16, and the process gas 25 are shown in combination with the workpiece 9. The workpiece 9 is located, as usual, in a horizontal position on the workpiece support 5.

[0106] First, let's consider the Figures 28A to 28CThe left-hand illustrations show the plate-shaped workpiece 9 with its two flat workpiece surfaces 17 and 20, and the cutting nozzle 13, in a schematic vertical sectional view. The right-hand illustrations of the Figures 28A to 28CThe process steps are illustrated schematically using respective top views. The upper workpiece surface 17 faces the cutting nozzle 13, while the lower workpiece surface 20 faces away from the cutting nozzle 13. The laser beam 16 exiting the nozzle tip 33 of the cutting nozzle 13 and the process gas 25 strike the workpiece 9. The laser beam 16 has the form of a focused beam cone with a central beam axis 27. The central beam axis 27, and thus the laser beam 16, is directed perpendicular to the upper workpiece surface 17. The process gas 25 exits the cutting nozzle 13 coaxially with the laser beam 16, with the laser beam 16 and the process gas 25 being guided together through the cutting nozzle. The processing beam 26 comprises the laser beam 16 and the process gas 25.

[0107] In Figure 28AThe cutting nozzle 13 was moved from a starting position towards the workpiece 9 with at least a vertical movement component, so that the cutting nozzle 13 has a relatively small working distance A from the workpiece 9. Preferably, the working distance A of the cutting nozzle 13 from the upper workpiece surface 17 is less than 2 mm. The focus position of the laser beam 16 results in a narrow beam spot with a small beam diameter on the workpiece 9. The focus position, and thus the beam diameter, is selected such that the line energy of the laser beam 16 on the workpiece 9 is high enough for the laser beam 16 to be suitable for cutting or separating the workpiece 9.

[0108] As in Figure 28AAs shown, the cutting laser beam 16 is guided along a circular pilot hole cutting line 32 to create a pilot hole 28, thereby producing a circular, closed cutting gap. This completely cuts out a round or disc-shaped waste piece (slug) from the workpiece 9. The cut-out slug falls downwards due to its own weight. Removing the slug from the workpiece 9 creates a round pilot hole 28 in the workpiece 9. The diameter of the pilot hole 28 is measured in the plane of the workpiece 9. Optionally, in a further process, a wider hole, namely an end hole 29, can be created from the pilot hole 28 by widening its diameter (see Figure 28C ).

[0109] The round (pre-)hole 28, according to its manufacturing method, is a through hole and penetrates the workpiece 9, wherein the (pre-)hole 28 is surrounded by a (pre-)hole wall 38 formed by the workpiece 9, which extends continuously from the upper workpiece surface 17 to the lower workpiece surface 20. At the upper workpiece surface 17, the (pre-)hole 28 is bounded by a circular upper (pre-)hole cutting edge 30, and at the lower workpiece surface 20 by a circular lower (pre-)hole cutting edge 31. The two (pre-)hole cutting edges 30, 31 are each part of the (pre-)hole wall 38. Figure 28A The (pre-)hole cutting line 32 and the upper (pre-)hole cutting edge 30 are shown relatively far apart for the sake of better graphic representation, although it is understood that this need not be the case in practice. The round (pre-)hole 28 is located with respect to its central axis 46 (see Figure 28B) radially symmetrical. In the plane of the workpiece 9, a radial direction is defined with respect to the (pre-)hole 28 and its central axis 46.

[0110] Optionally, the process can be supplemented by a step performed before cutting the (pre-)hole 28. This step is preferably used when (pre-)holes 28 with a diameter of at least 7 mm are to be produced and / or the workpiece 9 has a thickness of at least 4 mm. In this step, the slug to be cut out later along its contour is cut into smaller parts by one or more cutting slits, ensuring that the slug reliably and securely falls downwards out of the workpiece 9 and that the cut-out (pre-)hole 16 is always clear. For example, intersecting cutting slits, optionally superimposed by a spiral-shaped cutting slit, are introduced in the area of ​​the slug to be cut out. A possible method for dividing the slug is described, for example, in US 8716625 B2.

[0111] After creating the round (pre-)hole 28, a round chamfer or countersink zone 21 is created that is concentric to the (pre-)hole 28. This will be further explained using the following: Figure 28B illustrated.

[0112] For the production of the chamfer or countersink zone 21, the cutting nozzle 13 has a relatively large working distance A from the first workpiece surface 17, with the workpiece 9 being located in the divergent region of the laser beam 16, resulting 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 was moved away from the workpiece 9 with at least a vertical movement component, so that, compared to the production of the (pre-)hole 28, there is a larger working distance A between the cutting nozzle 13 and the first workpiece surface 17. The working distance A for producing the chamfer or countersink zone 21 is, for example, at least 6 times larger, and in particular at least 10 times larger, than the working distance A for producing the (pre-)hole 28, and is preferably at least 30 mm, particularly preferably at least 40 mm, and in particular approximately 40 mm.50 mm, with a range of 30 mm to 50 mm being preferred. Correspondingly, the beam spot and beam diameter on the workpiece 9 are significantly larger. For example, the cross-sectional area of ​​the beam spot on the workpiece 9 is at least 6 times larger, and 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 beam diameter of the laser beam 16 are selected such that the linear energy of the laser beam 16 on the workpiece 9 is relatively low, and the laser beam 16 only creates the chamfer or countersink zone 21 without penetrating the workpiece 9 (non-cutting machining). The laser beam 16 is in a non-cutting mode.

[0113] When generating the chamfer or countersink zone 21, the non-cutting laser beam 16 is moved in a (horizontal) plane parallel to the plane of the workpiece support 5, the laser beam 16 being moved along at least one chamfer or countersink generation line 44. The at least one chamfer or countersink generation line 44 is concentric to the (pre-)hole cutting line 32 and extends along the upper (pre-)hole cutting edge 30, wherein the chamfer or countersink generation line 44 corresponds, for example, to the upper (pre-)hole cutting edge 30 or is preferably offset radially further outwards from it. This means that the chamfer or countersink generation line 44 has a diameter that is equal to or preferably larger than the diameter of the upper (pre-)hole cutting edge 30.

[0114] A single chamfer or countersink generation line 44 can be provided for generating the chamfer or countersink zone 21, wherein the laser beam 16 is moved along the chamfer or countersink generation line 44 one or more times to generate the chamfer zone 21. Preferably, the laser beam 16 is moved along the chamfer or countersink generation line 44 several times to generate the chamfer or countersink zone 21 (typically 2 to 20 passes of the cutting nozzle 13). An offset (i.e., radial distance) of the chamfer or countersink generation line 44 from the upper (pre-)hole cutting edge 30 is preferably at least 0.5 mm, more preferably at least 1 mm, and more preferably 2 mm. The chamfer or sinking generation line 44 must be arranged so that the generated chamfer or sinking zone 21 directly borders the (pre-)hole 28, i.e., opens into the (pre-)hole 28.

[0115] For the generation of the chamfer or countersink zone 21, several chamfer or countersink generation lines 44 can also be provided, wherein the laser beam 16 is moved along each of the chamfer or countersink generation lines 44 one or more times to generate the chamfer or countersink zone 21. Preferably, the laser beam 16 is moved along each of the chamfer or countersink generation lines 44 several times to generate the chamfer or countersink zone 21 (typically 2 to 20 passes of the cutting nozzle 13). The several chamfer or countersink generation lines 44 are arranged concentrically to each other. An offset (i.e., radial distance) of the chamfer or countersink generation line 44 from the upper (pre-)hole cutting edge 30 or between two immediately adjacent chamfer or countersink generation lines 44 is preferably from 0.25 mm to 1 mm. The increase in diameter of two immediately adjacent chamfer or countersink generation lines 44 is preferably 0.25 mm to 1 mm.The chamfer or countersink generation lines 44 are therefore preferably 0.5 mm to 1 mm. The chamfer or countersink generation lines 44 must be arranged such that the generated chamfer or countersink zone 21 directly adjoins the (pre-)hole 28, i.e., opens into the (pre-)hole 28.

[0116] In Figure 28B The circular movement of the laser beam 16 along the at least one chamfer or sink line 44 around the central axis 46 of the (pre-)hole 28 is schematically illustrated by an arrow.

[0117] It would also be conceivable for the laser beam 16 to be moved along a spirally shaped chamfer or countersink generation line 44 to generate the chamfer or countersink zone 21. Preferably, an increase in the diameter of the spiral path of 0.25 mm to 1 mm is achieved with each complete revolution. After reaching the target diameter, it is advantageous to traverse it several times. In this case as well, the chamfer or countersink generation line 44 must be arranged such that the generated chamfer or countersink zone 21 directly adjoins the (pre-)hole 28, i.e., opens into the (pre-)hole 28.

[0118] The chamfer or countersink zone 21 is a recess in the workpiece 9 on the first workpiece surface 17. The chamfer zone 21 concentrically surrounds the (pre-)hole 28, extending from the upper workpiece surface 17 into the workpiece 9 from a (radially) outer chamfer or countersink edge 42 to a (radially) inner chamfer or countersink edge 43, but not to the lower workpiece surface 20. That is, the chamfer or countersink zone 21 does not extend over the entire thickness of the workpiece. The inner chamfer or countersink edge 42 is thus located between the upper workpiece surface 17 and the lower workpiece surface 20.

[0119] The outer chamfer or countersink edge 42 is defined as the area of ​​the workpiece 9 where the chamfer or countersink zone 21 begins to deepen towards the interior of the workpiece 9. The inner chamfer or countersink edge 42 is defined as the area of ​​the workpiece 9 where the chamfer or countersink zone 21 transitions into the remaining part of the (pre-)hole 28, with the inner chamfer or countersink edge 42 being formed by the (pre-)hole wall 38. A flank 45 of the chamfer or countersink zone 21 extends from the outer chamfer or countersink edge 42 to the inner chamfer or countersink edge 43.

[0120] In the radial direction, the chamfer or countersink zone 21 can be optionally provided with a defined cross-sectional shape. In particular, the focus position and thus the beam diameter can be varied during the generation of the chamfer or countersink zone 21 in order to precisely adjust the depth and / or cross-sectional shape of the chamfer or countersink zone 21. Reducing the beam diameter on the workpiece 9 results in a deeper chamfer or countersink zone 21, i.e., the flank 45 of the chamfer or countersink zone 21 becomes steeper. Conversely, increasing the beam diameter on the workpiece 9 results in a shallower chamfer or countersink zone 21, i.e., the flank 45 of the chamfer or countersink zone 21 becomes less steep. Figure 28B An example of a chamfer or subsidence zone 21 with a sloping flank 45 with an inclination of approximately 45° is shown, whereby larger or smaller flank inclinations are also possible.

[0121] The chamfer or countersink zone 21 can, in principle, be used in any way, but in this embodiment it is preferably designed to receive the head of a countersunk screw. Preferably, the radially outermost chamfer or countersink generation line 44 for generating the chamfer or countersink zone 21 has a diameter that is slightly smaller than the maximum diameter of the head of the countersunk screw to be installed in the chamfer or countersink zone 21. The number of chamfer or countersink generation lines 44 depends on the diameter of the (pre-)hole 28 or the thread diameter of the screw to be inserted and the desired depth of the chamfer or countersink zone 21. As a rule, for (pre-)holes 28 for receiving countersunk screws with a metric thread size M3 - M6 (i.e., for a diameter of the (pre-)hole 28 of 3 mm to 6 mm), at least two passes of the cutting nozzle 13 over the same chamfer orA countersink generation line 44 is required, with a typical number of passes ranging from two to 25. For countersunk screws with a metric thread size of M8 to M12, the number of passes is generally at least 5, preferably at least 10, and typically ranges from 10 to 25. Oxygen (O₂) is used as the process gas for generating the chamfer or countersink zone 21, for example, with a gas pressure of, for example, less than 5 bar, which is particularly between 2 and 3.5 bar. The feed rate of the cutting nozzle 13 when generating the chamfer or countersink zone 21 is preferably at least 4 m / min, and the laser power of the laser beam 16 is preferably at least 1500 W.

[0122] The (pre-)hole 28 allows the molten metal (slag) generated during the creation of the chamfer or countersink zone 21 to flow downwards very efficiently, thus preventing the molten metal from reaching the upper surface 17 of the workpiece 9, where it would solidify and form a burr. Such a burr would not only impair the subsequent use of the chamfer or countersink zone 21 and potentially require extensive rework, but in the worst case, it could also lead to a collision with the cutting nozzle 13. By optionally splitting the slurry to be cut during the creation of the (pre-)hole 28, it can always be ensured that the (pre-)hole 28 remains clear and that the molten metal generated during the creation of the chamfer or countersink zone 21 is reliably and safely expelled through the (pre-)hole 28 by the process gas. This is a major advantage of the invention.

[0123] Nevertheless, melt can deposit on the (pre-)hole wall 38, especially in the area of ​​the lower (pre-)hole cutting edge 31, and form a burr 37 after cooling, as shown in Figure 28B This ridge 37 is advantageously used in the optional widening of the (pre-)hole 28 to create the end hole 29 (see Fig. 28C ) removed, so that an end hole 29 with a burr-free end hole wall 39 can be produced. When such a further step is carried out, the hole 28 produced so far represents a "preliminary hole" whose diameter is widened to form the end hole 29.

[0124] The optional widening of the diameter of the hole or pilot hole 28 to create the final hole 29 is described below: After creating the chamfer or countersink zone 21, the pilot hole 28, or the portion remaining after creating the chamfer or countersink zone 21, is widened, as further explained below. Figure 28Cis illustrated.

[0125] To enlarge the diameter of the pilot hole 28, the laser beam 16 is used in cutting mode, analogous to the creation of the pilot hole 28. In this mode, the cutting nozzle 13 has a relatively small working distance A from the first workpiece surface 17, resulting in a narrow beam spot with a small beam diameter on the workpiece 9. For this purpose, the cutting head 3, or the cutting nozzle 13, was moved towards the workpiece 9 with at least a vertical movement component, so that, compared to the creation of the chamfer or countersink zone 21, there is a smaller working distance A between the cutting nozzle 13 and the first workpiece surface 17. The focus position, and thus the beam diameter of the laser beam 16, is selected such that the linear energy of the laser beam 16 on the workpiece 9 is relatively high, and the workpiece 9 is penetrated (cutting operation).

[0126] When widening the pilot hole 28, the cutting laser beam 16 is guided along a circular end-hole cutting line 37, thereby creating a circular, closed cutting gap. The end-hole cutting line 37 is concentric to the pilot hole cutting line 32 and radially outwardly spaced from it, i.e., it has a larger diameter than the pilot hole cutting line 32. The end-hole cutting line 37 is located radially between the pilot hole cutting line 32 and the outer edge of the chamfer or countersink zone 42, with the stipulation that a radial area of ​​the flank 45 is removed, but not the entire flank 45; i.e., the chamfer or countersink zone 21 remains partially intact. The end hole 29 is thus created within the chamfer or countersink zone 21. When widening the pilot hole 28, a disk with a hollow cylindrical cross-section is completely cut out of the workpiece 9.Due to its own weight, it falls downwards, thus being removed from workpiece 9.

[0127] By widening the pilot hole 28, a round end hole 29 is created in the workpiece 9, which has a larger diameter than the pilot hole 28. The end hole 29 is bounded by an end hole wall 39 formed by the workpiece 9 and extends from an upper end hole cutting edge 40, located between the upper workpiece surface 17 and the lower workpiece surface 20, to a lower end hole cutting edge 41, which is formed by the lower workpiece surface 20. The diameter D of the end hole 29 is preferably between 0.5 and 2 mm, and particularly approximately 1 mm larger, than the diameter of the previously created pilot hole 28. This ensures that any burr 37 adhering to the pilot hole wall 38 and to the lower workpiece surface 20 in the area of ​​the lower pilot hole cutting edge 31 is reliably and safely removed.

[0128] Preferably, a pulsed laser beam 16 is used to widen the pilot hole 28 for the creation of the final hole 29. This advantageously allows the workpiece 9 to heat up less during the creation of the final hole 29, resulting in a stronger metallic material at the machining point and a well-defined or sharp lower cut edge 41 of the final hole, which facilitates the flow of molten metal during the widening of the pilot hole 28. This measure helps to prevent molten metal from depositing, especially on the lower workpiece surface 20, and forming a burr.

[0129] Preferably, a pulsed laser beam 16 with an average power of at least 200 W and a peak pulse power of at least 2000 W and a pulse frequency between 10 Hz and 200 Hz is used. Depending on the workpiece material and the desired edge quality, nitrogen (N), compressed air or oxygen (O₂) can be used as the process gas.

[0130] As in Figure 28CAs shown, it is advantageous if the cutting nozzle 13 for creating the end hole 29 is moved downwards to such an extent that it enters the chamfer or countersink zone 21, i.e., the nozzle tip 33 is located below the upper workpiece surface 17 or below the plane defined by the upper workpiece surface 17. This has the particular advantage that both the laser beam 16 and the process gas 25 are less fanned out at the point of impact on the workpiece 9, so that more precise cutting is possible and the end hole 29 can be produced with particularly high precision. In addition, this prevents the molten material generated during the creation of the end hole 29 from being deposited on the upper workpiece surface 17 and forming a burr there.Furthermore, the highly focused process gas jet 25 allows the molten metal to be expelled particularly efficiently through the pilot hole 28, thus preventing molten metal from depositing on the upper workpiece surface 17. These are significant advantages that can be achieved through this measure.

[0131] Advantageously, the (pre-)hole 28 and the end hole 29 have a diameter that is equal to or smaller than the thickness of the workpiece 9. The inventive method also allows very small holes with chamfers or countersinks to be produced.

[0132] Reference will now be made to the Figures 29A to 29D taken, wherein a further exemplary embodiment of the inventive method for laser beam processing of a workpiece 9 by the beam device 1 of Figure 1 is illustrated schematically. The process steps of the Figures 28A, 28Band 28D correspond to the process steps of the Figures 29A, 29B and 29C , whereby, to avoid unnecessary repetition, reference is made to the above statements regarding the Figures 28A, 28B and 28C Reference is made to the Figures 29A to 29D The illustrated embodiment of the method according to the invention differs from the one based on the Figures 28A to 28C The illustrated design is only shown in the procedural step of Figure 29C .

[0133] Accordingly, after the creation of the chamfer or subsidence zone 21 ( Figure 29B ) and before widening the pilot hole 28 to create the end hole 29 ( Figure 29D ) active cooling of the chamfer or sinking zone 21 and the pilot hole 28 (or the remaining part of the pilot hole 28) by a gaseous or liquid cooling medium. As in Figure 29CAs illustrated, process gas 25 is advantageously used for this purpose, with the laser beam 16 switched off. The point of impact on the workpiece 9 is typically supplied with a process gas at an (initial) gas pressure in the range of 2 to 20 bar. The expanding process gas thus leads to very efficient cooling of the metallic workpiece 9, with the cooling efficiency increasing the hotter the workpiece 9 is. The active cooling makes the metallic material of the workpiece 9 stronger, so that the lower pre-hole cutting edge 31 is precisely defined, which facilitates the flow of the molten metal through the pre-hole 28. This measure also contributes to the precise adjustment of the geometry of the final hole 29. Furthermore, it prevents burrs from adhering to the lower workpiece surface 20.

[0134] As already explained, a procedure such as that described in the Figures 28A-28C and 29A-29D As illustrated, instead of a chamfer or countersink zone, a rounding zone is created on the workpiece-side cutting edge. Example 1 Production of chamfer or countersink zones for countersunk screws with metric thread sizes M3 - M6 using laser beam

[0135] First, a pilot hole is cut with a diameter approximately 1 mm smaller than the average core hole diameter of the countersunk screw, so that the melt generated in the next step during the creation of the chamfer or countersink zone can be driven out through the pilot hole.

[0136] Subsequently, with the cutting nozzle held at a large distance from the upper workpiece surface (approx. 50 mm) and the laser beam ignited, a circular chamfer or countersinking path with a diameter of 5 mm to 15 mm is traversed, using oxygen (O₂) as the process gas. The number of passes depends on the depth of the required chamfer or countersink, with typically two to 25 passes being performed. This creates the chamfer or countersink for the head of the countersunk screw. Alternatively, a spiral path can be traversed.

[0137] The pilot hole is then cut to standard dimensions using a pulsed laser beam, with the diameter of the final hole being approximately 1 mm larger than the diameter of the pilot hole. This allows for the reliable removal of slag adhering to the pilot hole and, in particular, to the lower tool surface in the area of ​​the lower pilot hole cutting edge. Advantageous cutting parameters are: pulsed average laser power (pulse frequency 10 Hz): 400 W, peak pulse power: 3000 W or 6000 W, feed rate: 0.1 m / min, distance between cutting nozzle and upper workpiece surface: 1.2 mm, process gas pressure: 3.3 bar. Example 2 Production of chamfer or countersink zones for countersunk screws with metric thread sizes M8 - M12 using a laser beam

[0138] Before cutting the pilot hole, the slug is split by creating cross-shaped kerfs with an overlaid spiral shape into the slug to be cut. This ensures that the slug of the pilot hole falls reliably, thus keeping the pilot hole clear at all times. This allows the melt generated during the chamfer or countersinking zone formation to be expelled through the pilot hole. The pilot hole is then cut with a diameter approximately 1 mm smaller than the average core hole diameter of the countersunk screw.

[0139] Subsequently, with the cutting nozzle held at a large distance from the upper workpiece surface (approx. 50 mm) and the laser beam ignited, a circular chamfer or countersink zone creation path with a diameter of 10 mm to 15 mm is traversed, using oxygen (O₂) as the process gas. The number of passes depends on the depth of the chamfer or countersink to be created, with 10 to 25 passes typically being performed. This creates the chamfer or countersink zone for the head of the countersunk screw. Alternatively, a spiral path is traversed.

[0140] The pilot hole is then cut to standard dimensions using a pulsed laser beam, with the diameter of the final hole being approximately 1 mm larger than the diameter of the pilot hole. Advantageous cutting parameters are: pulsed average laser power (pulse frequency 10 Hz): 400 W, peak pulse power: 3000 W or 6000 W, feed rate: 0.1 m / min, distance between cutting nozzle and upper workpiece surface: 1.2 mm, process gas pressure: 3.3 bar. Example 3 Production of a chamfer or countersink zone for a countersunk screw with metric thread size M8 in 8 mm structural steel using a laser beam

[0141] Before cutting the pilot hole, the slug is split by creating cross-shaped kerfs with an overlaid spiral pattern in the slug to be cut. Oxygen (O₂), nitrogen (N₂), or compressed air is used as the process gas. The pilot hole is then cut with a diameter of 8 mm, which is approximately 1 mm smaller than the average core hole diameter of the countersunk screw.

[0142] Subsequently, with the cutting nozzle held at a considerable distance from the upper workpiece surface (approx. 50 mm) and the laser beam ignited, a circular chamfer or countersink zone formation path with a diameter of 12.6 mm is traversed using oxygen (O₂) as the process gas. Seventeen passes are performed, creating a chamfer or countersink zone with a diameter of 14 mm and a depth of 4.4 mm to 4.5 mm in the sheet metal. Alternatively, a spiral path is traversed. Advantageous laser parameters are: laser power: 4000 W, feed rate: 10 m / min, distance between cutting nozzle and upper workpiece surface (A): 50 mm, process gas pressure: 3.3 bar, focus diameter: 210 µm / 150 µm.

[0143] The pilot hole is then cut to a standard diameter of 9 mm using a pulsed laser beam, with oxygen (O₂) as the process gas. Advantageous cutting parameters are: pulsed average laser power (pulse frequency 10 Hz): 400 W, peak pulse power: 4000 W, feed rate: 0.7 m / min, distance between cutting nozzle and upper workpiece surface (A): 0.7 mm, process gas pressure: 17 bar, focus diameter: 210 µm.

[0144] The embodiments of the inventive method described above enable the efficient and cost-effective production of holes, each featuring a chamfer or countersink, in a workpiece or workpiece part with high precision and quality. A hole's chamfer or countersink can be produced in two steps: in a first step, a hole is created in the workpiece, followed by a second step in which a chamfer or countersink is formed around the hole (circumferential chamfer or countersink). Optionally, a third step can be added, in which the production of a hole with a chamfer or countersink then comprises three steps: in a first step, a hole is created in the workpiece, representing a pilot hole, followed by a second step in which a chamfer or countersink is formed around the pilot hole (circumferential chamfer or countersink).(sinking zone), followed by a third step in which the pilot hole is widened in diameter to create a final hole.

[0145] In the Figures 30A and B The positioning of the cutting nozzle 13, which guides the laser beam 16 and the process gas 25 together, is shown as an example. Figure 30A The cutting nozzle 13 is at a smaller distance from the workpiece 9, so that the processing jet is in cutting mode and the cutting gap 15 can be created. Figure 30B The cutting nozzle 13 has a greater distance from the workpiece 9, so that the processing jet is in non-cutting mode and a chamfer or countersink zone 21 (alternatively a rounding zone) can be created on one of the two cutting edges of the cutting gap 15.

[0146] In Figure 31 A flowchart of the method according to the invention is shown. The method comprises at least two successive steps.

[0147] In step I (first processing step), the workpiece is processed with a first processing beam guided along a cutting line, creating a cutting gap through the thickness of the workpiece, extending along the cutting line in length and limited in width by two cutting edges in the workpiece.

[0148] Subsequently, in step II (second processing step), the workpiece is processed with a second processing beam, which is guided along a post-processing line or zone that runs parallel and offset to one of the two cutting edges, thereby creating a rounding zone or chamfer or countersink zone on the workpiece in the area of ​​this cutting edge.

[0149] As described above, the invention provides a novel method for machining a workpiece, in which rounding zones or chamfered or countersinked zones can be produced in a simple, reliable, and rapid manner on the workpiece-side cut edge of a workpiece part still connected to the rest of the workpiece, or on the workpiece-side cut edge formed by cutting out a waste part from the workpiece. This eliminates the need for mechanical post-processing of the cut-out workpiece part, thus making the production of workpiece parts with rounding, chamfered, or countersinked zones simpler, faster, and more cost-effective. The method according to the invention can be easily implemented in existing laser beam processing devices without requiring complex technical measures.Rather, a desired laser beam processing of a workpiece can be achieved by simply intervening in the machine control using the method according to the invention. Reference symbol list

[0150] 1 Laser processing device 2 Laser cutting device 3 Cutting head 4 Worktable 5 Workpiece support 6 Crossbeam 7 Guide carriage 8 Laser beam source 9 Workpiece 10 Remaining workpiece 11 Workpiece section 12 Control device 13 Cutting nozzle 14 Cutting line 14-1, 14-2, 14-3, 14-4, 14-5 Section of cutting line 15 Cutting gap 15-1, 15-2, 15-3, 15-4, 15-5 Section of cutting gap 16 Laser beam 17 Top surface of workpiece 18 Post-processing line 19, 19' Cutting edge 20 Bottom surface of workpiece 21 Chamfer or countersink zone 22 Post-processing zone 22-1, 22-2, 22-3, 22-4, 22-4' Section of the post-processing zone 23 Web 24 Circle 25 Process gas 26 Machining jet 27 Jet axis 28 (Pre-)hole 29 End hole 30 Upper (Pre-)hole cutting edge 31 Lower (Pre-)hole cutting edge 32 (Pre-)hole cutting line 33 Nozzle tip 34 Rounding zone 35 Workpiece top 36 Workpiece bottom 37 Burr 38 (Pre-)hole wall 39 End hole wall 40 Upper end hole cutting edge 41 Lower end hole cutting edge 42 Outer chamfer orCountersink edge 43 inner chamfer or countersink edge 44 chamfer or countersink generation line 45 flank 46 center axis.

Claims

1. A method for machining a plate-shaped or tubular workpiece (9) with a machining beam (26) comprising a laser beam (16) and a process gas (25), the machining beam being directed onto a workpiece surface (17) for the purposes of machining the workpiece (9), wherein the workpiece (9) is machined in a first machining step with a first machining beam (26) that is guided along a cutting line (14, 37), whereby a cutting gap (15) reaching through the thickness of the workpiece is produced on the workpiece (9), the length of said gap extending along the cutting line (14, 37) and the width thereof being limited by two cutting edges (19, 19') in the workpiece (9), and wherein in a second machining step the workpiece (9) is machined with a second machining beam (26) that is guided along a follow-on machining line (18, 44) or follow-on machining zone (22) that runs parallel and offset relative to one of the two cutting edges (19, 19'), whereby a chamfered zone (21) is produced on the workpiece (9) in the region of said cutting edge (19, 19'), wherein the workpiece (9) consists of steel, in particular carbon steel or stainless steel, or aluminum, characterized in that the beam diameter of the first machining beam (26) on the workpiece surface (17) is less than 50% of the beam diameter of the second machining beam (26) on the workpiece surface (17), wherein the machining beam (26) is guided through a cutting nozzle (13) prior to its impinging on the workpiece surface (17), wherein the distance of the cutting nozzle (13) to the workpiece surface (17) is maximum 5 mm during the first machining step, and in the second machining step it is at least 15 mm, in particular at least 30 mm, wherein a laser power of the laser beam (16) is lower in the second machining beam (26) than in the first machining beam (26), wherein the process gas (25) of the second machining beam (26) is subjected to a lower gas pressure than the process gas (25) of the first machining beam (26), and wherein i) the process gas of the second machining beam (26) contains oxygen as a substantial component and is subjected to a gas pressure in the range of 2 bar to 4 bar, or i) the process gas of the second machining beam (26) contains nitrogen as a substantial component and is subjected to a gas pressure in the range of 0.3 bar to 1 bar.

2. The method according to claim 1, characterized in that the machining beam (26) is guided through a cutting nozzle (13) prior to its impinging on the workpiece surface (17), wherein a focus of the laser beam (16) of the second machining beam (26) lies inside the cutting nozzle (13), in particular in the range of 3 to 5 mm above a nozzle opening (33), and i) a focus of the laser beam (16) of the second machining beam (26) lies inside the cutting nozzle, in particular in the range of 1 to 6 mm above a nozzle opening (33), wherein the process gas (25) of the first machining beam (26) contains oxygen as a substantial component, or ii) a focus of the laser beam (16) of the first machining beam (26) lies outside the cutting nozzle, in particular in the range of 0 to 10 mm below a nozzle opening (33), wherein the process gas (25) of the first machining beam (26) contains nitrogen as a substantial component.

3. The method according to any one of claims 1 to 2, characterized in that the machining beam (26) is guided through a cutting nozzle (13) prior to its impinging on the workpiece surface (17), wherein a focus of the laser beam (16) is the second machining beam (26) lies in the range of 30 to 40 mm above the workpiece surface (17), and i) a focus of the laser beam (16) of the first machining beam (26) lies in the range of 2 to 7 mm above the workpiece surface (17), wherein the process gas (25) of the first machining beam (26) contains oxygen as a substantial component, or ii) a focus of the laser beam (16) of the first machining beam (26) lies on the workpiece surface (17) or in the workpiece (9), in particular 0 to 8 mm below the workpiece surface (17), wherein the process gas (25) of the first machining beam (26) contains nitrogen as a substantial component.

4. The method according to any one of claims 1 to 3, characterized in that the first machining beam (26) in the first machining step and the second machining beam (26) in the second machining step are always aligned perpendicular to the workpiece surface (17).

5. The method according to any one of claims 1 to 4, characterized in that the workpiece (9) has a thickness in the range of 3 mm to 60 mm.

6. The method according to any one of claims 1 to 5, characterized in that the first machining beam (26) comprises a different process gas than the second machining beam (26).

7. The method according to any one of claims 1 to 6, characterized in that the process gas (25) of the first machining beam (26) comprises nitrogen or oxygen as a substantial component, or a mixed gas consisting of nitrogen and oxygen, and the process gas (25) of the second machining beam (26) comprises nitrogen or oxygen as a substantial component, or a mixed gas consisting of nitrogen and oxygen.

8. The method according to any one of claims 1 to 7, characterized in that i) for a workpiece (9) made of carbon steel, the process gas (25) of the second machining beam (26) has oxygen as substantial component, or i) for a workpiece (9) made of stainless steel, the process gas (25) of the second machining beam (26) has nitrogen as substantial component.

9. The method according to any one of claims 1 to 8, characterized in that a gas pressure of the process gas (25) in the second machining beam (26) is changed relative to a gas pressure of the process gas (25) in the first machining beam (26), in particular as a function of a material thickness of the workpiece (9) and / or of a dimensioning of the chamfered zone.

10. The method according to any one of claims 1 to 9, characterized in that a laser power of the laser beam (16) in the second machining beam (26) is changed relative to a laser power of the laser beam (16) in the first machining beam (26), in particular as a function of a material thickness of the workpiece (9) and / or of a dimensioning of the chamfered zone.

11. The method according to any one of claims 1 to 10, characterized in that the laser power of the laser beam (16) in the second machining beam (26) is a maximum of 4 kW.

12. The method according to any one of claims 1 to 11, characterized in that the laser power of the laser beam (16) in the first machining beam (26) is in the range of 1 kW to 40 kW and in the second machining beam (26) is in the range of 0.5 kW to 4 kW.

13. The method according to any one of claims 1 to 12, characterized in that the cutting nozzle (13) has a nozzle diameter, wherein the same nozzle diameter is used for the first and the second machining beam (26), in particular the same cutting nozzle (13) is used.

14. The method according to any one of claims 1 to 13 characterized in that to produce the cutting gap (15) the first machining beam (26) is guided only once along the cutting line (14, 37) and that to produce the chamfered zone (21) the second machining beam (26) is guided multiple times along the follow-on machining line (18, 44) or follow-on machining zone (22).

15. The method according to claim 14, characterized in that the laser power of the laser beam (16) in the second machining beam (26) in the last guiding along the follow-on machining line (18, 44) or follow-on machining zone (22) is lower than for at least one prior guiding along the follow-on machining line (18, 44) or follow-on machining zone (22), and is reduced in particular by half the laser power.

16. The method according to any one of claims 1 to 15, characterized in that the energy input into the workpiece (9) per surface area and time in the first machining step is greater than in the second machining step.

17. The method according to any one of claims 1 to 16, characterized in that the phase zone (21) directly abuts the cutting edge (19, 19') or transitions into it.

18. The method according to any one of claims 1 to 17, characterized in that a workpiece part (11) is cut out of the workpiece (9) by means of the first machining step, forming the workpiece part (11) and a residual grid (10), wherein the outer contour of the workpiece part (11) is fixed by the cutting line (14), wherein the one of the two cutting edges (19, 19') is a workpiece part-side cutting edge (19) and the other of the two cutting edges (19, 19') is a residual grid-side cutting edge (19'), and wherein the workpiece part-side cutting edge (19) is machined by means of the second machining step.

19. The method according to claim 18, characterized in that to form the cutting gap (15), the first machining beam (26) is turned off at least once, in particular multiple times, and then turned back on again during the guiding along the workpiece surface (17), whereby the cutting gap (15) forms a plurality of cutting gap sections (15-1, 15-2, 15-3, 15-4, 15-5) such that a web (23) is arranged between two adjacent cutting gap sections (15-1, 15-2, 15-3, 15-4, 15-5), respectively, by way of which the workpiece part (11) and the residual grid (10) remains connected to one another.

20. The method according to any one of claims 1 to 19, characterized in that by means of the first machining step, a hole-shaped recess (28, 29) is cut out of the workpiece (9), forming a dropout piece and a workpiece part, wherein the outer contour of the dropout piece and the inner contour of the hole-shaped recess is specified in the workpiece part by the cutting line (37), wherein the one of the two cutting edges is a workpiece part-side cutting edge and the other of the two cutting edges is a dropout piece-side cutting edge, and wherein the workpiece part-side cutting edge is machined by means of the second machining step.

21. The method according to claim 20, characterized in that the hole-shaped recess (28, 29) has a diameter that is the same size as or is smaller than a workpiece thickness of the workpiece (9).