METHOD FOR PRODUCING AT LEAST ONE WORKPIECE PART AND A RESIDUAL WORKPIECE FROM A WORKPIECE

Description

[0001] The invention lies in the technical field of the production of metallic workpiece parts and relates to a method for laser processing a plate-shaped or tubular workpiece, in which a separating processing of the workpiece to produce a cutting gap and a non-separating and at the same time non-joining modification of the workpiece is carried out by a laser beam.

[0002] Commercially available laser cutting devices with a movable laser processing head for guiding a laser beam enable the automated production of workpiece parts in large quantities and with high precision. In this case, workpiece parts are cut out of a plate- or tubular metal workpiece along specific cutting lines using the laser beam.

[0003] Depending on the type of laser cutting process used and the intended use of the cut workpiece parts, the cut edges of the workpiece parts may require complex mechanical post-processing. For example, it may be desirable to round or chamfer sharp cut edges, as well as remove burrs, particularly those caused by slag or melt residues formed during laser processing.

[0004] In principle, mechanical processing of the cut edges following the complete cutting of a workpiece part is very time-consuming and often labor-intensive, especially since it is often performed manually. Furthermore, such post-processing is costly, which undesirably lengthens and increases the cost of manufacturing workpiece parts. Document US 2014 / 151347 discloses a method for cutting a workpiece, wherein a recess is created on the upper surface of the workpiece, and a cutting gap is subsequently created along the cutting line, with the cutting line located within the recess.

[0005] In contrast, the object of the present invention is to further develop conventional methods in which workpiece parts are cut out of a plate-shaped or tubular workpiece by means of a laser beam in such a way that the production of workpiece parts with chamfered or rounded cutting edges, as well as with removed burrs, can be carried out in an automated manner faster, more cost-effectively and with high quality.

[0006] This problem is solved by a two-stage process for producing a workpiece part and a remaining workpiece from the workpiece by means of a laser beam and a process gas for expelling molten workpiece material, which jointly exit from a nozzle of a laser processing head.

[0007] For the purposes of the present invention, the term "workpiece" refers to a plate- or tubular-shaped, typically metallic component from which at least one workpiece part (product part) is to be produced. The plate-shaped workpiece is typically planar or flat. Although the inventive method for blasting a plate- or tubular workpiece is explained using a single workpiece part, it is understood that, as a rule, a plurality of workpiece parts are produced from the workpiece.

[0008] In the method according to the invention, in addition to separating the workpiece to create a cutting gap, a non-separating and simultaneously non-joining modification of the workpiece is also carried out using a laser beam. By adjusting its power density, the laser beam can be used either for separating or alternatively for non-separating and simultaneously non-joining machining of the workpiece.

[0009] The energy density of the laser beam indicates the energy of the laser beam relative to the area of ​​the workpiece irradiated by the laser beam, for example, measured in J / mm 2 . Relevant for the creation of a cutting gap or a non-separating or non-joining modification of the workpiece is the energy density relative to the time interval in which the irradiated area of ​​the workpiece is irradiated, for example, measured in J / (mm 2 × s), referred to here and below as "power density." If the power density absorbed by the workpiece is crucial, the power density can also be understood as the power density absorbed by the workpiece.

[0010] The laser processing of a plate or tubular workpiece involves creating a cutting gap that severs the workpiece or one or more sections of the cutting gap along a cutting line of the workpiece part. The cutting line corresponds to a contour (i.e. outline) of the workpiece part to be produced from the workpiece. When creating the cutting gap, the laser processing head is moved over the workpiece, with the laser beam being guided along the cutting line. The cutting line is thus a predetermined or to be predetermined (imaginary) line or path along which the laser beam or laser processing head is guided to cut out the workpiece part contoured by the cutting line. When separating the workpiece, the laser beam has a power density that is dimensioned such that the workpiece is (completely) severed. The laser beam interacts with a process gas (cutting gas) directed at the cutting gap.The power density can take on different values ​​and does not have to be constant.

[0011] In the present description of the invention, the reference system is always stationary relative to the workpiece, so that the laser processing head is considered to be moving and the workpiece is considered to be stationary. However, from a local perspective, it is irrelevant whether the laser processing 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 laser processing head, or for both the laser processing head and the workpiece to be moved.

[0012] By creating the cutting gap or one or more sections of the cutting gap along the cutting line, the workpiece part is partially or completely cut out along its contour, i.e., the cutting gap always forms the contour. Accordingly, the term "cutting gap" within the meaning of the present invention does not include sections of the cutting gap that do not form the contour and do not extend along the contour of the workpiece part. For example, when cutting out a workpiece part, the workpiece is often cut away from the contour, and the laser beam is first moved a short distance toward the contour-forming cutting line of the workpiece part.

[0013] Cutting a workpiece part free from the workpiece, i.e. completely cutting out the workpiece part from the workpiece so that it can be detached or removed from the workpiece, is done by creating a closed cutting gap along the cutting line of the workpiece part.

[0014] For the purposes of the present invention, the remaining workpiece, if at least one workpiece part to be cut out is at least conceptually removed, is referred to as a "residual workpiece." According to the invention, a modification of the workpiece only occurs if the workpiece part has been partially, i.e., not completely, cut out, or, alternatively, if no separating machining has yet been performed on the workpiece part. The cutting gap is always defined by two opposing cutting edges, i.e., a cutting edge on the workpiece part side and a cutting edge on the remaining workpiece side.

[0015] A partially cut-out workpiece part remains firmly connected to the remaining workpiece (i.e., the remaining workpiece), i.e., the partially cut-out workpiece part is still an integral part of the workpiece. Within the meaning of the present invention, the connection of a partially cut-out workpiece part to the remaining workpiece is sufficiently rigid so that a change in position of the partially cut-out workpiece part relative to the workpiece (remaining workpiece) does not occur upon modification of the workpiece, or any change in position that may occur is negligibly small and does not lead to any reasonably appreciable change in the result of a modification of the workpiece according to the invention.

[0016] As usual, the laser beam emerges together with the process gas from a nozzle, which is part of a laser processing head. The nozzle is located opposite the top surface of the workpiece. The workpiece, in particular a plate-shaped workpiece, rests with its underside on a workpiece support. On the top surface of the workpiece, the workpiece has a (top-side) workpiece surface. In a plate-shaped workpiece, the workpiece surface is flat. Unless otherwise specified, the term "workpiece surface" here and in the following refers to the top surface of the workpiece that is opposite or facing the nozzle.

[0017] The method according to the invention comprises the following steps: Step a): Cutting a section of a kerf severing the workpiece along a cutting line, or alternatively, cutting a closed kerf along the cutting line, forming cutting edges on the workpiece part and the remaining workpiece. Step b): Creating a modification of the workpiece, selected from a chamfer, a fillet, and a trough, on the workpiece top surface along a modification line while the workpiece part is connected to the remaining workpiece.

[0018] In steps a) and b), the laser beam is aligned perpendicular to the workpiece surface. The process gas pressure in step b) is less than 7 bar, and in particular between 3 bar and 6 bar. This gas pressure (boiler pressure) applies within the laser processing head before the process gas exits the nozzle.

[0019] In the process according to the invention, step a) is carried out before step b).

[0020] Steps a) and b) can each be carried out several times in succession without the other step being carried out between two steps of the same name. According to one embodiment of the method according to the invention, a plurality of steps a) are carried out before one or more steps b). According to yet another embodiment of the method according to the invention, a plurality of steps a) and a plurality of steps b) are carried out in alternating sequence, wherein after a step with one name (i.e. step a) or b)), a step with the other name (i.e. step b) or a)) is carried out. The various embodiments of the method according to the invention can be combined with one another.

[0021] For example, step a) can be executed once or more than once, followed by step b) being executed once or more than once.

[0022] In the method according to the invention, step a) is performed before step b), whereby in step a), a section of the cutting gap is created along the cutting line. No closed cutting gap is created. Rather, the workpiece part remains connected to the remaining workpiece. Subsequently, in step b), at least a portion of at least one of the cutting edges on the workpiece part or on the remaining workpiece is provided with a chamfer or a rounded portion.

[0023] In the invention, after performing step a) or after performing a plurality of steps a), the workpiece part is further 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 mean a connection made of workpiece material between the workpiece part and the remaining workpiece, extending along the cutting line, 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, particularly preferably in the range of 1 / 10 mm to 1 mm. In the common usage of the term, a microjoint has a height that corresponds to the height or thickness of the workpiece (i.e., the dimension perpendicular to the workpiece surface).A "nanojoint" is a microjoint whose height is reduced relative to the thickness of the workpiece. According to the invention, the height of a nanojoint is preferably a maximum of half the thickness of the workpiece. Microjoints and nanojoints are well known to those skilled in the art from the practice of manufacturing sheet metal workpieces by laser processing and from patent literature, so they need not be discussed in detail here. For additional information regarding nanojoints, reference is made to, for example, international patent application WO 2019025327 A2.

[0024] Accordingly, after carrying out step a) or after carrying out step a) multiple times, at least a part of at least one of the cut edges formed on the workpiece part or on the remaining workpiece is provided with a chamfer or rounding, while the workpiece part is still connected to the remaining workpiece. Only then is the workpiece part cut free, for example by the laser beam or manually, for example by breaking the workpiece part out of the workpiece. According to a preferred embodiment of the method according to the invention, the cutting line and the modification line run parallel, wherein the modification line has a lateral offset perpendicular to the cutting line. In this embodiment of the method, the cutting line and the modification line are therefore not identical, i.e. they do not have an identical course.

[0025] In a particularly advantageous embodiment of the method according to the invention, in step b) the at least one web, in particular a microjoint or nanojoint, is also modified, i.e. provided with a chamfer or a rounded portion. As the inventors have surprisingly discovered, a web between the workpiece part and the remaining workpiece only slightly disrupts the gas dynamics of the process gas if the web is sufficiently small along the cutting line. This applies in particular if the web is designed as a microjoint and has a dimension along the cutting line in the range from 1 / 10 mm to 2 mm, particularly preferably in the range from 1 / 10 mm to 1 mm. Particularly advantageously, this is a nanojoint whose height preferably corresponds to a maximum of half the thickness of the workpiece.This procedure is particularly advantageous when creating a fillet, since a sharp-edged workpiece edge is only melted on the workpiece surface and contracts into a fillet due to the high surface tension of the liquid melt.

[0026] The inventors recognized that for creating a rounded or chamfered cutting edge on a workpiece, it is advantageous if the workpiece is connected to the remaining workpiece, meaning that there is still workpiece material on both sides of the cutting gap. This fixes the workpiece in its position and prevents it from slipping or tilting, allowing the laser beam to be precisely positioned to the cutting edge when creating the chamfer or rounding. Furthermore, the melt created when creating the chamfer or rounding flows into the cutting gap and can be removed more easily from it than from the top of the chamfer—particularly when oxygen is used as the process gas.

[0027] When creating a bevel or rounding, it is necessary to apply not only the laser beam but also the process gas jet to the workpiece to remove the resulting melt or slag. The pressure of the process gas before exiting the nozzle must not exceed 7 bar to avoid excessive material splashing on the workpiece surface. The gas pressure is preferably between 3 bar and 6 bar, which ensures effective removal of the melt while reliably and safely preventing material splashing.

[0028] Preferably, the distance between the nozzle from which the laser beam emerges and the workpiece surface is greater in step b) than in step a) to achieve a less concentrated, "softer" effect of the process gas on the workpiece surface. Furthermore, the greater distance of the nozzle from the workpiece surface enables a larger beam spot on the workpiece. This, in particular, enables the production of wider bevels.

[0029] In principle, an advantageous distance between the nozzle and the workpiece or the workpiece surface according to the invention depends on the process gas used. According to an advantageous embodiment of the invention, the distance between the nozzle and the workpiece surface in step b) for creating chamfers using oxygen as the process gas is preferably at least 9 mm, better at least 20 mm, and particularly preferably at least 35 mm. For creating fillets using nitrogen as the process gas, the distance between the nozzle and the workpiece in step b) is preferably at least 1 mm, better at least 6 mm, and particularly preferably at least 9 mm.

[0030] According to an advantageous embodiment of the invention, oxygen is preferably used as the process gas in step b) for a workpiece made of structural steel. In this way, the melt formed is advantageously completely oxidized in the cutting gap and can therefore be easily removed from the workpiece.

[0031] In the method according to the invention, the power density or the energy per unit length of the laser beam at the workpiece in step b) is lower than in step a), which can preferably be achieved by reducing the power of the laser beam, increasing the feed rate of the laser processing head containing the nozzle, defocusing the laser beam by changing the focus position relative to the workpiece and / or by changing the beam diameter at the workpiece surface.

[0032] The beam diameter perpendicular to the beam axis at any given point on the laser beam determines the power density of the laser beam at that point. The beam diameter is the diameter of the circular cross-sectional area of ​​the laser beam perpendicular to the beam axis. For processing far from the focus, the larger the beam diameter, the lower the power density, and vice versa. In the area between the focusing lens or focusing mirror and the focus, the laser beam converges; beyond the focus, the laser beam diverges. Viewed in the direction of beam propagation, the power density increases in the convergent area with increasing distance from the focusing lens or focusing mirror, has its highest value at the focus, and decreases in the divergent area with increasing distance from the focus.

[0033] The power density on the workpiece thus depends on the size of the irradiated area (beam spot on the workpiece), corresponding to the beam diameter at the point where the laser beam hits the workpiece. The beam diameter on the workpiece depends on the focus position of the laser beam. The term "focus position" refers to the position of the focus relative to the workpiece, in particular relative to the plane of the workpiece surface. The focus position is the vertical (shortest) distance of the focus from the workpiece surface. By changing the focus position, the beam diameter on the workpiece can be changed. If the workpiece is located in the divergent area of ​​the beam cone (focus above the workpiece surface), the beam diameter on the workpiece can be increased by increasing the distance between the focus and the workpiece, and vice versa.

[0034] Thus, by changing the beam diameter on the workpiece, the power density on the workpiece can be specifically altered. With a laser, the beam intensity outside the focus is not constant relative to the cross-section. Ideally, the power intensity is a Gaussian profile. In any case, the power density is relatively low toward the edge, especially outside the focus.

[0035] In an advantageous embodiment of the method according to the invention, the focus of the laser beam in step b) is on or above the workpiece surface. The average laser power in step b) is preferably less than 3500 W, the focus diameter of the laser beam is preferably at least 150 µm, and / or the feed rate is preferably at least 1 m / min.

[0036] The closer the focus of the laser beam is to the workpiece, the larger the focus diameter should be in step b). For example, the focus diameter for a focus position on the workpiece surface is preferably more than 250 µm.

[0037] According to the invention, the cutting line and modification line are selected so that they run parallel and have a lateral offset perpendicular to the cutting line. The offset between the cutting line and the modification line is preferably at least 0.2 mm and no more than 1.5 mm, whereby a desired modification of the workpiece can be created efficiently and reliably.

[0038] The method is advantageously carried out in such a way that in order to create a chamfer or rounding on the cutting edge, only a single action of the laser beam on the workpiece is necessary and no multiple movements of the laser beam along the modification line are carried out.

[0039] In the method according to the invention, the laser beam is guided along the modification line in step b). According to one embodiment of the method according to the invention, the laser beam is always moved in a straight line along the modification line in step b). In this case, the path of the laser beam along the modification line is identical to the modification line. A chamfer or rounding on an already formed cutting edge can thus be created by a straight-line movement of the laser beam along the modification line, which enables particularly rapid modification of the workpiece. Likewise, a depression on the workpiece surface can be created particularly quickly in a simple manner.

[0040] In the method according to the invention, according to an alternative embodiment, particularly for both method variants, it may be advantageous to also move the laser beam transversely to the modification line in step b). In this case, the movement of the laser beam in step b) along the modification line includes, in addition to movement components along the modification line, movement components transverse (i.e., perpendicular) to the modification line, so that a larger area of ​​the workpiece is covered by the laser beam.

[0041] According to a preferred embodiment of the method according to the invention, the laser beam performs a meandering back-and-forth movement along the modification line. During its movement along the modification line, the laser beam is guided away from the modification line and then back towards it several times.

[0042] According to an alternative preferred embodiment, the laser beam is guided along closed path sections, which are preferably arranged in rows along the modification line. Each closed path section is defined by a crossing of the previously traversed path of the laser beam. For example, the closed path sections are circular, closed path sections (i.e., circles) or ellipses, which are preferably arranged in rows along the modification line. In this way, chamfers with greater chamfer depths and / or chamfer widths can be produced along the modification line. Advantageously, a movement component of the laser beam transverse to the modification line has an extent of at least 0.5 mm and at most 5 mm.

[0043] When moving along closed path sections, in particular along circles or ellipses, the laser beam preferably has an overlap along the modification line in the range of 0.5 mm to 1 mm. Advantageously, the overlap of closed path sections (e.g., circles) along the modification line is 0.5 mm to 1 mm.

[0044] In a further development of the process, after steps a) and b), a further process step c) is carried out, in which slag / melt formed during steps a) and b) is removed from the workpiece.

[0045] Step c) comprises the removal of slag from at least one of the cut edges or chamfer edges on the workpiece part or remaining workpiece, wherein the laser beam is moved along the cut line or a line laterally offset therefrom, and / or the removal of slag from a chamfer or a fillet, wherein the laser beam is moved along the modification line or a line laterally offset therefrom.

[0046] The power density or the energy per unit length of the laser beam at the workpiece is lower in step c) than in step a). As a rule, the laser power during slag / melt removal is significantly lower than during the cutting process, with the average power preferably being less than 1000 W. The distance between the nozzle and the workpiece surface is preferably greater in step c) than in step a) and is preferably at least 5 mm, preferably between 6 mm and 12 mm. The gas pressure of the process gas in the laser processing head is preferably lower in step c) than in step a) and is preferably less than 7 bar, preferably between 0.7 bar and 6 bar. The focus diameter of the laser beam is preferably at least 150 µm.

[0047] According to an advantageous embodiment of the method, the laser beam used in step c) simultaneously cuts the workpiece part free from the remaining workpiece, wherein the laser beam power for this purpose is preferably at least 500 W. This is particularly advantageous when the workpiece part is connected to the remaining workpiece by one or more nanojoints (i.e., microjoints with a reduced height), which can be easily severed by the laser beam used to remove the slag.

[0048] In the method according to the invention, according to the first method variant, one or more sections of the cutting gap are created. For example, adjacent sections of the cutting gap border a web, in particular a microjoint or nanojoint. However, it is also possible for the cutting gap to be successively extended by the sections.

[0049] In the method according to the invention, a modification of the workpiece occurs in any case when the workpiece part has not been cut free or when no separating machining has yet been performed on the workpiece part. The workpiece is modified along the modification line, whereby, particularly when the laser beam is also moved transversely to the modification line, the modification of the workpiece occurs in a relatively wide modification zone. It is understood that the modification zone also extends along the modification line.

[0050] Like the creation of the cutting gap, the modification of the workpiece can also be performed section by section, i.e., the modification can be performed sequentially, for example, by separating the workpiece, in several sections. A modification of the workpiece can also be performed in an area of ​​the workpiece along the modification line that does not have a cutting gap, particularly in the area of ​​one or more webs.

[0051] When modifying the workpiece, the laser beam has a power density that is lower than the power density used for cutting the workpiece. This means that if a cutting gap has already been created, the partially cut-out part of the workpiece will not be reconnected to the remaining workpiece across the cutting gap when modifying the workpiece. Likewise, no opening in the workpiece is created when modifying the workpiece.

[0052] According to one embodiment of the process according to the invention, at least two sections, preferably several sections, of the cutting gap are created. The separating machining of the workpiece is thus interrupted at least once, with preferably at least one web remaining between the workpiece part and the remaining workpiece. Preferably, a last-created section of the cutting gap has a length measured along the cutting line that is smaller than the respective length of any other previously created section of the cutting gap. For example, the lengths of the successively created sections of the cutting gap, viewed from a free-cutting point on the workpiece part, do not decrease opposite to the direction of creation of the cutting gap.Since a modification of the workpiece only occurs when the workpiece part is still firmly connected to the workpiece, this measure can be used to particularly advantageously ensure that the workpiece can be modified along as large a portion of the cutting line as possible. The unmodified portion of the workpiece, to which the partially cut-out workpiece part is still connected, is thus small compared to the modified portion. Alternatively, the workpiece can also be modified along the modification line where there is no cutting gap.

[0053] A modification of the workpiece can take place in a region that contains the cutting edge of the cutting gap on the workpiece part side and / or the cutting edge of the remaining workpiece side, whereby it is equally possible for the cutting edge of the cutting gap on the workpiece part side and / or the cutting edge of the remaining workpiece side to not be included. For example, an initial modification of the workpiece takes place in a modification zone that contains the cutting edge of the cutting gap on the workpiece part side and / or the cutting edge of the remaining workpiece side, and each further modification no longer contains the cutting edges. This configuration is particularly advantageous when creating a chamfer on the cutting gap, whereby during a subsequent modification the laser beam can be moved further into the workpiece part or remaining workpiece in a direction away from the cutting edge, for example in order to widen the chamfer.In the case of a multiple modification, a modification zone of a subsequent modification may at least partially contain a modification zone of a preceding modification.

[0054] If multiple modifications are performed, identical or different modification lines and / or identical or different laser beam power densities can be used. The direction of movement of the laser beam for modifying the workpiece can be the same or opposite to the direction of movement of the laser beam for generating the cutting gap.

[0055] According to one embodiment of the method according to the invention, the distance of the modification line from the cutting line is a maximum of half the gap width of the cutting gap plus the radius of a beam cone of the laser beam at the workpiece surface. However, it is also possible for the distance of the modification line from the cutting line to be greater, for example in the multi-stage production of a bevel, in which the modification line in a subsequent modification is arranged further away from the cutting gap than the modification line of a previous modification. In the multi-stage production of a bevel, the modification zone contains at least one cutting edge during an initial modification, whereby the modification zone no longer contains the cutting edge during a subsequent modification.

[0056] When modifying the workpiece, the laser beam has a power density that is dimensioned such that a non-joining and simultaneously non-separating (although possibly remelting) modification of the workpiece is effected. During the modification, therefore, a connection is neither created between the partially cut-out workpiece part and the remaining workpiece across the cutting gap, nor is the workpiece severed. The influence of the process gas is taken into account here, whereby the power density of the laser beam can also be understood to mean the power density absorbed by the workpiece. A change in the power density or the absorbed power density can be achieved by various measures, in particular by changing the energy of the laser beam, changing the beam focus, changing the distance of the nozzle from the workpiece surface, changing the type and / or parameters of the process gas, and the like.The measures for changing the power density are well known to those skilled in the art, so they need not be discussed in detail here. Advantageously, the power density is changed solely by changing the vertical distance of the nozzle from the workpiece surface. For example, when modifying the workpiece, the power density is less than 50%, less than 40%, less than 30%, less than 20%, less than 10%, or less than 1% of the power density during the cutting process. Short description of the drawings

[0057] The invention will now be explained in more detail using exemplary embodiments, with reference to the accompanying figures. They show: Fig. 1 a schematic representation of an exemplary laser processing device for carrying out the method according to the invention; Fig. 2-16 an exemplary method for laser processing a workpiece according to the invention Fig. 17-18another exemplary method for laser processing a workpiece according to the invention Fig. 19-22 various configurations of a non-rectilinear movement of the laser beam along the modification line; Fig. 23-31 various forms of modification of a workpiece; Fig. 32-36 another exemplary method for laser processing a workpiece, which lies outside the scope of the claims. Fig. 37 a flow chart of the method according to the invention. Detailed description of the drawings

[0058] First, be Figure 1, in which a known laser processing device for laser cutting plate-like workpieces is illustrated. The laser processing device, designated overall by the reference number 1, comprises a laser cutting device 2 with a laser processing head 3, as well as 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.

[0059] The workpiece support 5 is spanned by a cross member 6, which is guided for movement along a first axial direction (x-direction). A guide carriage 7 for the laser processing head 3 is mounted on the cross member 6 and is guided for movement on the cross member 6 along a second axial direction (y-direction) perpendicular to the first axial direction. The laser processing head 3 can thus be moved in a plane spanned by the two axial directions (x-, y-direction) parallel to and relative to, for example, the horizontal workpiece support 5. The laser processing head 3 is also designed to be vertically movable in a third axial direction (z-direction) perpendicular to the first and second axial directions, whereby the distance perpendicular to the workpiece support 5 or workpiece 9 can be changed. With a horizontal workpiece support 5, the z-direction corresponds to the direction of gravity.

[0060] The laser processing head 3 has, on its side facing the workpiece support 5, a nozzle 13 which tapers conically towards the workpiece support 5. The laser processing head 3 serves to guide a laser beam 16 (see e.g. Figures 2 to 16 ), as well as a process gas jet (not shown in the figures). 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 laser processing head 3. The laser beam 16 can be directed in bundled form (i.e. focused) onto the workpiece 9 via a focusing lens or adaptive optics. Due to the movability of the laser processing head 3 along the first axial direction (x-direction) and second axial direction (y-direction), any point on the workpiece 9 can be approached with the laser beam 16.

[0061] The workpiece 9 has two opposing workpiece surfaces 17, 20 (see e.g. Figure 23 ), wherein a first workpiece surface 17 on a workpiece upper side 35 faces the nozzle 13 and a second workpiece surface 20 on a workpiece lower side 36 faces away from the nozzle 13. Due to the height movability of the laser processing head 3 in the z-direction, the (working) distance of the nozzle 13 to the workpiece 9 can be adjusted by changing the distance to the upper workpiece surface 17. The distance of the laser processing 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 nozzle 13 from the upper workpiece surface 17 and / or via optical elements in the laser processing head 3, for example an adaptive optics.

[0062] A process gas serves to drive the melt out of the kerf. The process gas is generated by a gas jet generation device (not shown). For example, helium (He), argon (Ar), or nitrogen (N 2 ) are used as inert working gases. Oxygen (O 2 ) is usually used as a reactive working gas. The use of gas mixtures is also known. The process gas has a predetermined cutting gas pressure (boiler pressure) within the laser processing head 3, exits the nozzle 13 at this pressure, and is guided coaxially to the laser beam 16 to the processing point.

[0063] As in Figure 1As shown, the flat workpiece support 5 consists, for example, of a plurality of support elements with, for example, triangular support point tips, which together define a support plane for the workpiece 9 to be machined. The support elements are designed here, for example, as elongated support webs, each extending along the y-direction and arranged next to one another in a parallel arrangement along the x-direction with, for example, a constant spacing. Not shown in detail is an extraction device, by which cutting smoke, slag particles, and small waste pieces generated during laser cutting can be extracted.

[0064] A program-controlled control device 12 serves to control / regulate the method according to the invention for laser processing the workpiece 9 in the laser processing device 1.

[0065] Reference is now made to the Figures 2 to 16taken, in which exemplary embodiments of the inventive method for laser machining a workpiece 9 according to the invention (ie step a) is carried out before step b) are illustrated. The Figures 2 to 16 correspond in this order to later procedural situations.

[0066] First, be Figure 2 , in which a cutting line 14 (dashed) is shown. The cutting line 14 is an imaginary line which corresponds to the contour of a workpiece part 11 to be produced from the workpiece 9. The contour represents the external shape of the workpiece part 11. The workpiece part 11 is to be completely cut out of the plate- or tubular workpiece 9 (not shown in detail), leaving the remaining workpiece 10. The workpiece part 11 here has, for example, a rectangular shape with rounded corners, although it is understood that the workpiece part 11 can have any desired shape.

[0067] In Figure 3The laser beam 16 emerging from the laser processing head 3 is schematically illustrated. The laser beam 16 is guided along the cutting line 14, whereby, with a corresponding power density on the workpiece 9, a cutting gap 15 is generated in the workpiece 9. For this purpose, the laser processing head 3 has been moved to a position above the cutting line 14 in which the laser beam 16 strikes a cutting position A of the cutting line 14. As in Figure 3 As illustrated, the laser processing head 3 is moved along the cutting line 14, wherein the laser beam 16 is moved from the cutting position A to a cutting position B. As a result, a cutting gap 15 (solid line) is generated which cuts through the workpiece 9 from the cutting position A to the cutting position B.

[0068] As will be apparent from the further explanations, the cutting gap 15 is generated in sections, with a first section 15-1 of the cutting gap 15 being generated first. The first section 15-1 of the cutting gap 15 is correspondingly generated in a first section 14-1 of the cutting line 14. The laser beam 16 can also penetrate into the workpiece 9 away from the cutting line 14, with the cutting gap 15, in the sense of the present invention, extending only along the contour (ie, cutting line 14) of the workpiece part 11.

[0069] In Figure 4 A situation is illustrated in which the first section 15-1 of the cutting gap 15 has been completely created from the cutting position A to the cutting position B. The separating machining of the workpiece 9 is now interrupted. The laser beam 16 is switched off and the laser processing head 3 is moved to a modification position A' near the cutting position A. As in Figure 4As illustrated by an arrow, the movement of the laser processing head 3 occurs, for example, in a direct line between the cutting position B and the modification position A'. The modification position A' lies on a modification line 18 (see Figure 5 ).

[0070] As in Figure 5 and the other Figures 6 to 16As shown, the modification line 18 is laterally offset and arranged equidistant from the cutting line 14. The laser processing head 3 is moved along the modification line 18 during the modification of the workpiece 9, wherein the movement of the laser processing head 3 can be rectilinear or non-reciprocal along the modification line 18, as will be explained in more detail below. A modification of the workpiece 9 takes place in a modification zone 22, which typically has a wider dimension perpendicular to its extension than the modification line 18, which is not shown in the drawing. The modification zone 22 is to be understood as the area of ​​the workpiece 9 that is modified by the laser irradiation. Corresponding to the modification line 18, the modification zone 22 also extends along the cutting line 14. The cutting gap 15 is delimited by two opposing cutting edges 19, 19' (see, for example, Figure 23 ).

[0071] As in Figure 5 As illustrated, the laser beam 16 is then switched on again and the laser processing head 3 is moved along the modification line 18 (dashed line), wherein the laser beam 16 is moved from the first modification position A' to a second modification position B' near the cutting position B. In this case, a modification of the workpiece 9 takes place in a first section 22-1 of the modification zone 22.

[0072] In Figure 6 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 modification zone 22, is schematically illustrated by a solid line. Analogous to the section-by-section creation of the cutting gap 15, the modification zone 22 is also created section-by-section.

[0073] As in Figure 6As illustrated, starting from the cutting position B, the workpiece 9 is further machined to separate it, whereby the already created first section 15-1 of the cutting gap 15 is extended to a cutting position C.

[0074] In Figure 7 Illustrates a situation in which a further or second section 15-2 of the cutting gap 15 has been created from the cutting position B to the 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 laser processing head 3 is moved in a straight line to a position above the modification position B', as indicated by an arrow.

[0075] As in Figure 8illustrated, the laser beam 16 is now switched on again and the laser processing head 3 is moved along the modification line 18, wherein the laser beam 16 is moved from the modification position B' to a modification position C' near the cutting position C.

[0076] In Figure 9 A situation is shown in which the workpiece 9 has been modified along the entire second section 15-2 of the cutting gap 15 between the modification position B' and the modification position C' in a further or second section 22-2 of the modification zone 22. The second section 22-2 of the modification zone 22 extends the previously created first section 22-1 of the modification zone 22.

[0077] As in Figure 9 As illustrated, the workpiece 9 is then further machined starting from the cutting position C, whereby the already generated part of the cutting gap 15 is extended to a cutting position D.

[0078] In Figure 10 Illustrates a situation in which a third section 15-3 of the cutting gap 15 was created from the cutting position C to the 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 laser processing head 3 is moved to a position above the modification position C' of the modification line 18 for the subsequent modification. The third section 15-3 of the cutting gap 15 extends the second section 15-2 of the cutting gap 15.

[0079] As in Figure 11 illustrated, the laser beam 16 is now switched on again and the laser processing head 3 is moved along the modification line 18, wherein the laser beam 16 is moved from the modification position C' to a modification position D' near the cutting position D.

[0080] In Figure 12A situation is shown in which the workpiece 9 has been modified along the entire third section 15-3 of the cutting gap 15 from the modification position C' to the modification position D' in a third section 22-3 of the modification zone 22. The third section 22-3 of the modification zone 22 extends the previously created second section 22-2 of the modification zone 22.

[0081] As in Figure 12 As illustrated, starting from the cutting position D, the workpiece 9 is now further machined to separate it, whereby the already created part of the cutting gap 15 is extended to a cutting position E.

[0082] In Figure 13Illustrated is a situation in which a fourth section 15-4 of the cutting gap 15 was created from the cutting position D to the 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.

[0083] The laser beam 16 is now switched off and the laser processing head 3 is moved to a position above the modification position D' of the modification line 18 for the following modification.

[0084] As in Figure 14 illustrated, the laser beam 16 is switched on again and the laser processing head 3 is moved along the modification line 18, wherein the laser beam 16 is moved from the modification position D' to a modification position E' near the cutting position E.

[0085] In Figure 15A situation is shown in which the workpiece 9 has been modified along the entire fourth section 15-4 of the cutting gap 15 from the modification position D' to the modification position E' in a fourth section 22-4 of the modification zone 22. The fourth section 22-4 of the modification zone 22 extends the previously created third section 22-3 of the modification zone 22.

[0086] As in Figure 15As illustrated, the workpiece 9 is then further machined to separate it, starting from the cutting position E, wherein the part of the cutting gap 15 already created is extended along a fifth section 14-5 of the cutting line 14 as far as the cutting position A. As a result, the cutting gap 15 is closed and the workpiece part 11 is cut free from the remaining workpiece 10 so that it can be removed. No further modification of the cut-free workpiece part 11 takes place, since no modification is made to the cut-free workpiece part 11 by the method according to the invention. In this case, a fifth section 15-5 of the cutting gap 15 is created, which extends the fourth section 15-4 of the cutting gap 15.

[0087] In all separating operations, the laser beam 16 has a power density dimensioned such that the workpiece 9 is severed. In all modifications, the laser beam 16 has a power density dimensioned such that the workpiece 9 is neither joined nor severed. As a result, the workpiece 9 is modified along the cutting line 14. The beam axis of the laser beam 16 is, for example, axially parallel to the conical nozzle 13 and strikes the workpiece 9 perpendicularly. In all separating operations and in all modifications, the laser beam 16 is directed onto the workpiece surface 17 with an unchanged perpendicular orientation of its beam axis relative to the workpiece surface 17.

[0088] The modifications can be varied in many ways. For example, the modification positions could also be positioned such that the 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 modification 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 modification could also be opposite to the direction of generation of the cutting gap 15.

[0089] According to one embodiment of the method, a respective section 14-1 to 14-5 of the cutting line 14 can be subjected to only a single modification. However, it is also possible for multiple modifications to be performed for the same part or section 14-1 to 14-5 of the cutting line 14.

[0090] As is particularly evident from Figure 16 As can be seen, during the last (fifth) cutting process, a part or section 15-5 of the cutting gap 15 is created whose length is smaller than the respective lengths of the sections of the cutting gap 15 created during all previous cutting processes. This measure can advantageously ensure that the smallest possible part of the cutting gap 15 is not subjected to any modification. It would also be possible for the lengths of the parts of the cutting gap 15 created during the cutting processes to increase continuously, for example, starting from the free cutting point of the workpiece part 11.

[0091] With regard to a complete modification of the workpiece part 11, the following embodiment of the method according to the invention is particularly advantageous. After the reworking of the workpiece 9 in the fourth section 22-4 of the modification zone 22, but before the creation of the fifth section 15-5 of the cutting gap 15, i.e. before the free cutting of the workpiece part 11, a modification of the workpiece 9 is carried out along a fifth section 14-5 of the cutting line 14 between the modification positions E' and A'. This is illustrated by an insertion in Figure 15illustrated schematically. Here, the fourth section 22-4 of the modification zone 22 is extended up to the modification position A'. The extended fourth section 22-4' of the modification zone 22 extends here accordingly up to the modification position A', so that the modification zone 22 extends as a closed, elongated region completely over the entire contour of the workpiece part 11. In particular, with such a modification, a chamfer can advantageously be created on one or both cutting edges of the cutting gap 15 to be created later, also in the region of the fifth section 14-5 of the cutting line 14. The workpiece part 11 is then cut free by creating the fifth section 15-2 of the cutting gap 15.

[0092] It is understood that the number of sections 14-1 to 14-5 of the cutting line 14 or the sections 15-1 to 15-5 of the cutting gap 15 in the embodiments of the Figures 2 to 16is exemplary and can be larger or smaller.

[0093] Based on the Figures 2 to 16 Exemplary embodiments of the method according to the invention were described, wherein in an alternating sequence a separating machining of the workpiece 9 and then a modification of the workpiece 9 takes place. Likewise, it would also be possible to first create different sections of the cutting gap 15, which are separated from each other by webs, in particular microjoints or nanojoints, wherein a modification of the workpiece 9 then takes place. This is shown in the Figures 17 and 18 illustrated.

[0094] As in Figure 17As shown, according to a further embodiment of the method according to the invention, three sections 15-1, 15-2, 15-3 of a cutting gap 15 are initially created, which are separated from one another by webs 23, here for example micro-joints or nanojoints. To create the sections 15-1, 15-2, 15-3 of the cutting gap 15, the laser beam 16 is pierced 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 formed along a Figure 17 cutting line 14, not shown in detail. 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.

[0095] As in Figure 18illustrated, after the sections 15-1, 15-2, 15-3 of the cutting gap 15 have been created, the workpiece 9 is modified, the laser beam 16 being guided along a modification line 18. The modification line 18 is laterally offset and arranged equidistant from the cutting line 14. The modification line 18 extends in particular also beyond the regions of the cutting line 14 in which a web 23 is arranged, i.e. the workpiece 9 is also modified in the region of the webs 23. As tests by the inventors have surprisingly shown, with correspondingly small-sized webs 23, the workpiece 9 can be sufficiently modified, since the gas dynamics of the process gas are only slightly impaired as a result.

[0096] After modification of the workpiece 9, the webs 23 are severed, 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 modification of the workpiece 9 in the area of ​​the webs 23 already severes the webs 23, so that the modification simultaneously cuts free the workpiece part 11. This can be particularly the case if the webs 23 are designed as nanojoints with a reduced height.

[0097] When generating 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. When modifying the workpiece 9, the laser beam 16 is guided in a straight line or non-straight line along the modification line 18. In particular, the laser beam 16 can also have movement components transverse (perpendicular) to the modification line 18 when modifying the workpiece 9. This can be seen from the Figures 19 to 22 illustrated.

[0098] In the Figures 19 to 22 Various exemplary configurations for guiding the laser beam 16 along the modification line 18 are shown. For a simple graphic representation, it is assumed that the modification line 18 extends horizontally from left to right.

[0099] In Figure 191 shows a variant in which the laser beam 16 is guided along closed circles 24 (i.e. closed path sections of the laser beam 16), which are arranged in rows along the modification line 18. After traversing each circle 24, the laser beam 16 is moved a short distance in a straight line along the modification line 18 and then guided along the next circle 24. The circles 24 overlap in the direction of the modification line 18. Instead of circles, the laser beam 16 could also be guided along ellipses. The movement of the laser beam 16 thus has movement components in a straight line along the modification line 18 and transverse to the modification line 18. The modification 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, in particular for producing deep and / or wide bevels.

[0100] In the Figures 20 to 22 Variants are illustrated in which the laser beam 16 is guided in a meandering manner with back and forth movements along the modification line 18. Here, too, the movement of the laser beam 16 includes movement components transverse to the modification line 18. In Figure 20 the meandering movement of the laser beam 16 is rectangular, in Figure 21 triangular (sawtooth-shaped) and in Figure 22 sinusoidal in shape. This is to be understood only as an example, although other meandering movements of the laser beam 16 are equally possible. In principle, any meandering back-and-forth movement of the laser beam 16 that extends along the modification line 18 is possible and provided for according to the invention. The meandering movement of the laser beam 16 can also produce a relatively wide modification zone 22, in particular for producing particularly deep and / or wide bevels.

[0101] Reference is now made to the Figures 23 to 33 taken, in which various embodiments for a modification of the workpiece 9 are illustrated.

[0102] In Figure 23 During the modification of the workpiece 9 by the laser beam 16, the workpiece-side cutting edge 19 of the workpiece part 11 adjacent to the workpiece surface 17 of the workpiece top side 35 is rounded by remelting, whereby a rounding 34 is produced. The modification line 18 is arranged laterally offset (e.g. equidistant) relative to the cutting line 14, wherein it is preferred if a maximum distance between the modification 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 on the workpiece surface 17. This is in Figure 23 not shown.

[0103] In Figure 24During the modification of the workpiece 9 by the laser beam 16, the workpiece part-side cutting edge 19 adjacent to the workpiece surface 20 on the workpiece underside 36 is rounded at the same time, whereby a rounding 34 is generated, and the remaining workpiece-side cutting edge 19' adjacent to the workpiece surface 17 is smoothed. The modification line 18 is offset laterally (e.g. equidistantly) relative to the cutting line 14, which in Figure 24 is not shown.

[0104] In Figure 25 During the modification of the workpiece 9 by the laser beam 16, the workpiece-side cutting edge 19 adjacent to the upper workpiece surface 17 is provided with a chamfer 21. The modification line 18 is offset laterally (e.g. equidistantly) relative to the cutting line 14, which in Figure 25is not shown. Here, the chamfer 21 is created, for example, through several steps or modifications that are carried out on the same section of the cutting gap 15. In a first modification, the workpiece part 11 is irradiated in an area containing the workpiece-side cutting edge 19. The modification line 18 is offset laterally (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 in order to form the chamfer 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 displacement of the modification line 18 in the direction of the cutting gap 15, whereby finally the workpiece-side cutting edge 19 is also irradiated. Particularly advantageously, when generating the bevel 21, the laser beam 16 is moved in a meandering manner along the cutting line 14 or along circles or ellipses arranged in rows, as can be seen from FIG. Figures 19 to 22 is illustrated, whereby the width and / or depth of the chamfer 21 can be increased considerably.

[0105] In Figure 26During the modification of the workpiece 9 by the laser beam 16, burrs are simultaneously removed from the cutting edge 19 on the part side of the workpiece and from the cutting edge 19' on the remaining workpiece side adjacent to the underside of the workpiece surface. The modification line 18 can be identical to the cutting line 14 or different from it, which in Figure 26 not shown. The focus position of the laser beam 16 is adjusted so that the two cutting edges 19, 19' are irradiated accordingly.

[0106] In the design of Figure 27 First, a cutting gap 15 is created. Then, a chamfer 21 is created on the workpiece-side cutting edge 19, whereby an adhesion in the form of slag 25 is formed. As in Figure 28 As illustrated, the slag 25 can be removed by the laser beam 16.

[0107] In the design of Figure 29a chamfer 21 is produced on the workpiece-side cutting edge 19, whereby burrs, here e.g. slag 25, are produced on the chamfer 21 on the upper workpiece surface 17 and in the cutting gap 15. The slags 25 are each shown enlarged (see enlarged illustrations A, B above Figure 29 ). As can be seen from the Figures 30 and 31 As illustrated, the slag 25 on the workpiece surface 17 and in the cutting gap 15 is removed by the laser beam 16.

[0108] Based on the Figures 32 to 36 Further embodiments of a variant not according to the invention (ie step b) is carried out before step a)) are described.

[0109] First, be Figure 32, in which the plate-shaped workpiece 9 with the two mutually parallel, flat workpiece surfaces 17, 20 and the nozzle 13 are shown. The laser beam 16 emerging from the nozzle 13 (as well as the process gas not shown in detail) strikes the upper workpiece surface 17. The laser beam 16 is in the form of a beam cone with a central beam axis 26 and focused at a focus 27. The central beam axis 26, which corresponds to the axis of symmetry of the beam cone, is directed perpendicular to the first workpiece surface 17. The nozzle 13 has a relatively large working distance A from the first workpiece surface 17 and the focus 27 is located close to the nozzle 13, whereby the workpiece 9 is located in the divergent area of ​​the laser beam 16, which leads to a relatively wide beam spot 28 with a relatively large beam diameter D on the workpiece 9 or the upper workpiece surface 17.The beam diameter D is measured perpendicular to the beam axis 26 and at the point where the laser beam 16 strikes the workpiece 9. The focus position and thus the beam diameter D are selected such that the power density of the laser beam 16 on the workpiece 9 is relatively low and the laser beam 16 only creates a depression 29 and the workpiece 9 is not penetrated (non-cutting machining).

[0110] When creating the trough 29, the laser beam 16 or the nozzle 13 is moved in a (horizontal) plane parallel to the plane of the workpiece support 5. The movement of the laser beam 16 when creating the trough 29 generally comprises at least one horizontal movement component. The movement of the laser beam 16 can also be composed of two mutually perpendicular (e.g., horizontal) movement components (x and y directions), wherein the laser beam 16 is moved along a curved path 30, in particular along an open or closed circular path (see also Figure 34 ). The path 30 of the laser beam 16 corresponds to the modification line 18. The trough 29 thus always has an elongated or extended shape. The longitudinal shape or course of the trough 29 can be freely defined.

[0111] Perpendicular to its extension, the trough 29 can be optionally provided with a defined cross-sectional shape. In particular, the focus position and thus the beam diameter D can be varied during the creation of the trough 29 in order to specifically adjust the depth and / or cross-sectional shape of the trough 29. When the beam diameter D on the workpiece 9 is reduced, the trough 29 becomes deeper, i.e., the flanks become steeper, whereas the trough 29 becomes flatter, i.e., the flanks become less steep, when the beam diameter D on the workpiece 9 is increased.

[0112] In Figure 34 The creation of an elongated trough 29 is schematically illustrated by way of example. Accordingly, the laser beam 16 is moved along a curved (non-rectilinear) path 30 along a modification line 18, whereby the trough 29 is created with a corresponding profile.

[0113] Subsequently, a cutting gap 15 is created within the trough 29, which is also Figure 33is illustrated. For example, to create the cutting gap 15, the beam head 3 or the nozzle 13 is moved towards the upper workpiece surface 17 (in the vertical direction), so that, compared to creating the recess 29, there is a significantly smaller working distance A between the nozzle 13 and the upper workpiece surface 17. The working distance A for creating the cutting gap 15 is, for example, at least 6 times smaller, in particular at least 10 times smaller, than the working distance A for creating the recess 29. Correspondingly, the beam spot 28 and the beam diameter D on the workpiece are significantly smaller. For example, the cross-sectional area of ​​the beam spot 28 on the workpiece 9 is at least 6 times smaller, in particular at least 10 times smaller. The focus 27 of the laser beam 16 is located within the workpiece 9.Specifically, the beam diameter D for generating the cutting gap 15 is dimensioned such that the power density of the laser beam 16 on the workpiece 9 leads to a separating machining (penetration) of the workpiece 9.

[0114] In addition, Figure 35considered. When generating the cutting gap 15, the laser beam 16 is moved in a plane parallel to the plane of the workpiece support 5 (e.g., horizontal). The movement of the laser beam 16 when generating the cutting gap 15 comprises two mutually perpendicular (e.g., horizontal) movement components (x and y directions), wherein the laser beam 16 is moved along a cutting line 14, whereby the cutting gap 15 is generated. The cutting line 14 is arranged within the recess 29. The cutting line 14 corresponds to the contour of a workpiece part 11 to be cut out of the workpiece 9. The cutting line 14 here, for example, has a non-linear and non-circular profile, although a circular profile would also be possible. As in Figure 35 As illustrated, the trough 29 does not extend, for example, along the entire cutting line 14, but only along a section thereof.

[0115] The cutting gap 15 is generated within the recess 29 and extends beyond it. The cutting gap 15 has an elongated or extended shape. The longitudinal shape or course of the cutting gap 15 can be freely defined, provided that the cutting gap 15 always follows the cutting line 14 or contour of the workpiece part 11 and is formed within the recess 29. Within the recess 29, the course of the cutting gap 15 corresponds to the course of the recess 29.

[0116] The paths of the laser beam 16 during the creation of the trough 29 and the cutting gap 15 are arranged equidistantly. As in Figure 35As illustrated, the laser beam 16 is guided beyond the recess 29 when generating the cutting gap 15, and the cutting gap 15 is closed, so that the workpiece part 11 (in the form of an inner slug) is cut free from the workpiece 9. By separating the workpiece part 11 from the remaining workpiece 11, an opening or hole is created in the remaining workpiece 11.

[0117] In a variant not shown, the recess 29 could, for example, have a circular, closed profile, whereby the cutting gap 15 would also have a circular, closed profile following the profile of the recess 29. In this case, a circular or disc-shaped workpiece part 11 would be cut out of the workpiece 9, creating a circular hole in the remaining workpiece 10.

[0118] It would also be conceivable that the workpiece part 11 is not completely cut out (freed) by the laser beam 16, but that one or more webs (e.g., microjoints) remain between the workpiece part 11 and the remaining workpiece 10. The webs can be severed by the laser beam 16 or otherwise in order to remove the workpiece part 11 from the remaining workpiece 10. For example, the workpiece part 11 could be broken out of the workpiece 9.

[0119] Where the trough 29 is formed, the cutting gap 15 is always arranged within the trough 29, whereby the cutting gap 15 is generated parallel to the path of the trough 29. As in Figure 35 As illustrated, the cutting gap 15 is arranged, for example, centered with respect to a direction perpendicular to the extension of the trough 29. The beam spot 28 for generating the cutting gap 15 is located only within the trough 29.

[0120] The trough 29 is delimited or surrounded on the upper workpiece surface 17 by a (closed) trough edge 31. The trough 29 is a depression or recess of the workpiece 9 on the workpiece surface 17. The trough edge 31 is defined as that region of the workpiece 9 at which the trough 29 begins to deepen towards the interior of the workpiece 9. The cutting gap 15 is always spaced from the trough edge 31 in a direction perpendicular to the extension of the trough 29 (in particular when viewed perpendicularly through the plane of the workpiece surface 17), i.e. the cutting gap 15 always has a distance from the trough edge 31 that is different from zero in a direction perpendicular to the extension of the trough 29.

[0121] Preferably, the cutting gap 15 is centered within the trough 29 in a direction perpendicular to the extension of the trough 29, wherein it always has a constant (constant) shortest distance from the trough edge 31. The cutting gap 15 is located in view perpendicular through the flat workpiece surface 17 in a direction perpendicular to the extension of the trough 29 within the trough 29, ie relative to a (vertical) projection of the cutting gap 15 and trough 29 into the plane of the workpiece surface 17. The trough 29 deepens towards the cutting gap 15, wherein the cutting gap 15 is arranged in the trough base.

[0122] The recess 29 forms, for example, a rounded cutting edge of the cutting gap 15. The recess 29 is particularly advantageously designed such that it is a chamfer 21 of the cutting gap 15. Preferably, the cutting gap 15 is designed as a closed gap, in particular as an annular closed gap (annular gap), so that a hole remains in the workpiece 9. The cutting gap 15 can then advantageously serve for fastening a workpiece part to be cut out of the workpiece 9, wherein a screw or rivet head can be countersunk into the remaining portion of the recess 29, which serves as a chamfer. The recess 29 has a recess section 32' on the remaining workpiece side and a recess section 32 on the workpiece part side.

[0123] In Figure 36The remaining workpiece 10 is shown with hole 33 after removal of the workpiece part 11. The remaining workpiece 10 has the remaining trough section 32' of the trough 29 at the hole 33 (the other trough section 32 is located on the removed workpiece part 11). The trough section 32' can be formed, for example, as a chamfer.

[0124] It would also be possible to form the hole 33 circular and to form a completely circumferential recessed section 32', for example in the form of a chamfer. Advantageously, the hole 33, possibly with one or more additional holes, is located within the contour of a larger workpiece part 11', which can be cut out by the laser beam 16. Figure 36Such a workpiece part 11' is schematically indicated by a contour. In this way, workpiece parts with holes, each with a chamfer, can be produced particularly easily. The holes can be used, in particular, for fastening the subsequently cut-out workpiece part 11'.

[0125] In the embodiments of the method not according to the invention described above, first a depression 29 was created, followed by a cutting gap 15 within the depression 29. If a plurality of depressions 29, each with a cutting gap 15, are created in the workpiece 9, it is possible for the cutting gap 15 to be created within the depression 29 immediately after the creation of a respective depression 29. However, it is also possible for several depressions 29 to be created in immediate succession, without a cutting gap 15 being created between the creation of two depressions 29, followed by the creation of a cutting gap 15 within a respective depression 29, wherein the cutting gaps 15 are created in immediate succession, without a depression 29 being created between the creation of two cutting gaps 15.

[0126] In Figure 37A flowchart of the method according to the invention is illustrated. The method comprises cutting a section (15-1, 15-2, 15-3, 15-4, 15-5) of a cutting gap (15) separating the workpiece (9) along a cutting line (14) or cutting a closed cutting gap (15) along the cutting line (14), whereby cutting edges (19, 19') are formed on the workpiece part (11) and the remaining workpiece (10) (step a).

[0127] The method further comprises producing a modification of the workpiece (9), selected from a chamfer (21), a rounding (34) and a depression (29), on a workpiece top side (35) along a modification line (18), while the workpiece part (11) is connected to the remaining workpiece (10) (step b).

[0128] In steps a) and b), the laser beam is aligned perpendicular to the workpiece surface. The process gas pressure in step b) is less than 7 bar, and in particular between 3 bar and 6 bar.

[0129] According to the invention, in step a) a section (15-1, 15-2, 15-3, 15-4, 15-5) of the cutting gap (15) is produced along the cutting line (14), and subsequently in step b) at least a part of at least one of the cutting edges (19, 19') on the workpiece part (11) or on the remaining workpiece (10) is provided with a chamfer (21) or a rounding (34).

[0130] As can be seen from the above description, the invention provides a novel method for beam machining a plate- or tubular workpiece, in which the workpiece part not yet cut free and / or the remaining workpiece is modified by the laser beam along a modification line. This eliminates the need for mechanical modification of the cut-free workpiece part, so that the production of workpiece parts can be carried out more simply, quickly, and cost-effectively. In a particularly advantageous manner, the rigid, fixed position between the workpiece part and the remaining workpiece allows for particularly precise modification of the, in particular, partially cut-out workpiece part, so that high quality requirements can be met.The method according to the invention can be easily implemented in existing laser processing devices without the need for complex technical measures. Rather, a desired modification of the workpiece can be achieved using the method according to the invention simply by intervening in the machine control system. List of reference symbols

[0131] 1Laser processing device 2Laser cutting device 3Laser processing head 4Work table 5Workpiece support 6Cross beam 7Guide carriage 8Laser beam source 9Workpiece 10Remaining workpiece 11, 11'Workpiece part 12Control device 13Nozzle 14Cutting line 14-1, 14-2, 14-3, 14-4, 14-5Section of the cutting line 15Cutting gap 15-1, 15-2, 15-3, 15-4, 15-5Section of the cutting gap 16Laser beam 17Top workpiece surface 18Modification line 19, 19'Cutting edge 20Bottom workpiece surface 21Bevel 22Modification zone 22-1, 22-2, 22-3, 22-4, 22-4'Section of the modification zone 23Web 24Circle 25Slag 26Blast axis 27Focus 28Blast spot 29Hole 30Track 31Hole edge 32, 32'Hole section 33Hole 34Filling 35Top of workpiece 36Bottom of workpiece

Claims

1. A method for producing at least one workpiece part (11) and a residual workpiece (10) from a workpiece (9) by means of a laser beam (16) emerging from a nozzle (13) of a laser processing head (2) together with process gas for expelling molten workpiece material, comprising the following steps: Step a): Cutting of a section (15-1, 15-2, 15-3, 15-4, 15-5) of a cutting gap (15) which separates the workpiece (9) along a cutting line (14) or cutting of a closed cutting gap (15) along the cutting line (14), wherein cutting edges (19, 19') are formed on the workpiece part (11) and residual workpiece (10), Step b): Producing a modification of the workpiece (9), selected from a chamfer (21) and a fillet (34), on a workpiece upper side (35) along a modification line (18) while the workpiece part (11) is connected to the residual workpiece (10), wherein the laser beam (16) in steps a) and b) is oriented perpendicular to a workpiece surface (17) of the workpiece upper side (35) and characterized in that - Step a) is carried out before step b), wherein in step a) a section (15-1, 15-2, 15-3, 15-4, 15-5) of the cutting gap (15) is produced along the cutting line (14), and subsequently in step b) at least a part of at least one of the cutting edges (19, 19') on the workpiece part (11) or on the residual workpiece (10) is provided with a chamfer (21) or a fillet (34), wherein a gas pressure of the process gas prior to exiting the nozzle in step b) is less than 7 bar, in particular between 3 and 6 bar.

2. The method according to claim 1, in which, in step b), a distance (A) between a nozzle (13) emitting the laser beam (16) and the workpiece surface (17) is greater than in step a), wherein the distance (A) between a nozzle (13) emitting the laser beam (16) and the workpiece surface (17) i) is at least 9 mm, at least 20 mm or at least 35 mm when producing a chamfer (21) with oxygen as the process gas, or ii) is at least 1 mm, at least 6 mm or at least 9 mm when producing a fillet (34) with nitrogen as the process gas.

3. The method according to claim 1 or 2, in which, in step b): i) a focus (27) of the laser beam (16) lies on or above the workpiece surface (17), ii) an average power of the laser beam (16) is less than 3500 W, iii) a focal diameter (D) of the laser beam (16) is at least 150 µm, and / or vii) a feed rate of the laser processing head (2) is at least 1 m / min.

4. The method according to any one of claims 1 to 3, wherein oxygen is used as a process gas in step b) for a workpiece (9) made of structural steel.

5. The method according to any one of claims 1 to 4, wherein a power density of the laser beam (16) in step b) is reduced with respect to a power density in step a) by: i) reducing the power of the laser beam (16), ii) increasing the feed rate of the laser beam (16), iii) defocusing the laser beam (16) by changing a focal position, and / or iv) changing a beam diameter (D) of the laser beam (16) on the workpiece surface (17).

6. The method according to any one of claims 1 to 5, wherein the cutting line (14) and the modification line (18) are parallel and a lateral offset between the cutting line (14) and the modification line (18) is at least 0.2 mm and at most 1.5 mm.

7. The method according to any one of claims 1 to 6, wherein in step b) the laser beam (16) is always moved in a straight line along the modification line (18).

8. The method according to any one of claims 1 to 6, wherein in step b) the movement of the laser beam (16) along the modification line (18) comprises movement components transverse to the modification line (18), wherein the laser beam (16) in particular i) performs a meandering back and forth movement along the modification line (18), and / or ii) is moved along closed path sections, in particular closed circles (24) or ellipses, which are arranged along the modification line (18).

9. The method according to claim 8, in which i) a movement component of the laser beam (16) transverse to the modification line (18) has an extension of at least 0.5 mm and at most 5 mm, and / or ii) an overlap of the closed path sections (24) of the laser beam (16) along the modification line (18) is in the range of 0.5 mm to 1 mm.

10. The method according to any one of claims 1 to 9, wherein after steps a) and b) a further step c) is carried out, which comprises: - removal of slag (25) formed during steps a) and b) from at least one of the cut edges (19, 19') on the workpiece part (11) or on the residual workpiece (10), wherein the laser beam (16) is moved along the cutting line (14) or a line laterally offset thereto, and / or - removal of slag (25) formed during steps a) and b) from a chamfer (21) or a fillet (34), wherein the laser beam (16) is moved along the modification line (18) or a line laterally offset thereto.

11. The method according to claim 10, in which, in step c) i) a laser power is less than a laser power in step a), and in particular is less than 1000 W, ii) a distance (A) between the nozzle (13) and the workpiece surface (17) is greater than in step a) and in particular is at least 5 mm, in particular between 6 mm and 12 mm, iii) a gas pressure is less than 7 bar, in particular between 0.7 bar and 6 bar, and / or iv) a focal diameter (D) of the laser beam (16) is at least 150 µm.

12. The method according to one of claims 10 or 11, wherein the laser beam (16) used in step c) cuts the workpiece part (11) free from the residual workpiece (10), wherein a laser power of the laser beam (16) is in particular at least 500 W.

13. The method according to claim 1, in which, i) a plurality of steps a) are carried out before one or a plurality of steps b), and / or ii) a plurality of steps a) and a plurality of steps b) are carried out in alternating sequence, wherein a step with one designation is followed in each case by a step with the other designation.

14. The method according to any one of claims 1 to 13, wherein, if one or a plurality of steps a) are carried out before one or a plurality of steps b), one or a plurality of sections (15-1, 15-2, 15-3) of the cutting gap (15) are produced along the cutting line (14), wherein the workpiece part (11) remains connected to the residual workpiece (10) by one or a plurality of webs (23), in particular microjoints or nanojoints, and then, in the one or a plurality of steps b), at least one part of at least one of the cut edges (19, 19') on the workpiece part (11) or on the residual workpiece (10) and the webs (23) are provided with a chamfer (21) or a fillet (34).