CN118159384A

CN118159384A - Method for producing a workpiece part with a chamfered cutting edge

Info

Publication number: CN118159384A
Application number: CN202280071940.2A
Authority: CN
Inventors: P·马赫; D·莫克; F·泽普; C·魏斯
Original assignee: Ws Optical Technology Co ltd; Trumpf European Ag
Current assignee: Ws Optical Technology Co ltd; Trumpf European Ag
Priority date: 2021-10-25
Filing date: 2022-10-10
Publication date: 2024-06-07
Also published as: EP4422819A1; DE102021005295A1; WO2023072568A1

Abstract

The invention relates to a method for producing at least one workpiece part (11) and a workpiece remainder (10) from a workpiece (9) by means of a laser beam (16) which is jointly emitted from a nozzle (13) of a laser processing head (2) and a process gas beam (25) for discharging a melt (26), comprising the following method steps: stage I: step a): cutting along the cutting line (14) sections (15-1, 15-2, 15-3, 15-4, 15-5) of the cutting gap (15) or cutting along the cutting line (14) the closed cutting gap (15), wherein a workpiece-part-side cutting edge (19) is formed at the workpiece part (11) and a workpiece-remainder-side cutting edge (19') is formed at the workpiece remainder (10); step b): -generating at least one partial recess (27) of the cutting gap (15) in the remainder of the workpiece (11), phase II: generating a chamfer (21) on the upper workpiece surface (17) at the workpiece-part-side cutting edge (19) along the modification line (18) while the workpiece part (11) is connected to the workpiece rest (10), wherein (I) in step a) of phase I at least one corner region (28, 29) of the cutting gap (15) is generated, for step b) of phase I a partial depression (27) of the cutting gap (15) is generated in the workpiece rest (10), such that a melt (26) formed in the corner region (28) during the generation of the chamfer (21) can be discharged through the partial depression (27), and/or (II) for the chamfer (21) generated in phase II at the starting point (36) of the generation of the chamfer (21), wherein the starting point can be located in particular at the cutting gap starting point (35) of the sections (15-1, 15-2, 15-3, 15-4, 15-5) of the cutting gap (15) is generated in the workpiece rest (10), such that a partial depression (27) of the cutting gap (15) can be generated in the workpiece rest (10) such that a melt (26) can be discharged through the partial depression (27) during the generation of the chamfer (21) and/or the expansion of the chamfer (27) can be generated in the phase II, the chamfer (21) is designed such that its depth and/or width in at least one first cutting gap region (32) is greater than its depth and/or width in the immediately adjacent second cutting gap region (33, 33'), wherein a partial recess (27) of the cutting gap (15) is produced in the remainder of the workpiece (10) such that the melt (26) formed in the first cutting gap region (32) during the production of the chamfer (21) can be discharged through the partial recess (27).

Description

Method for producing a workpiece part with a chamfered cutting edge

Technical Field

The present invention is in the field of producing metal workpiece parts by using laser beams and relates to a method for producing workpiece parts with chamfered cutting edges from plate-shaped or tubular workpieces.

Background

Commercial laser cutting devices have a movable laser processing head for guiding the laser beam, which enables automatic production of large and high-precision workpiece parts. In this case, the workpiece parts are cut out of the metal workpiece along the respective cutting lines by means of a laser beam.

Depending on the type of laser cutting process used and the purpose of the workpiece portion being cut, costly mechanical reworking of the cut edge may be required. It may thus be necessary in particular for the cutting edge to be provided with a chamfer, for example for welding or painting preparations or in order to meet specific geometric requirements for the workpiece part. In principle, the machining of the cutting edge, which is carried out after the cutting out of the workpiece part, is very time-consuming and in most cases also very labor-intensive, since it is usually carried out manually. This applies in particular to chamfering the cut edge. Furthermore, the cost of such reworking is very high, thus increasing the time and cost of manufacturing the workpiece portion with the chamfered cutting edge in an undesirable manner.

It is known in the patent literature to chamfer the cut edge of the part of the workpiece that is connected to the remainder of the workpiece by means of a laser beam. International patent application WO 2020/173970 A1 thus describes a method in which the cutting edge of a part of the workpiece that has not been cut off is provided with a chamfer by means of a laser beam.

During laser cutting of metal workpiece parts, a process gas is applied to the cutting location, by means of which process gas the melt formed during cutting, i.e. the melted workpiece material, is discharged through the cutting gap. This applies in a corresponding manner to chamfering of the cut edge by means of a laser beam, as is known from the aforementioned international patent application. In this case, too, the melt that occurs during the formation of the chamfer must be discharged through the cutting gap.

Now, it has been shown in practice that: in chamfering the cutting edge, the removal of the melt through the cutting gap by means of the process gas may cause problems, depending on the specific movement conditions, such as the course of the cutting gap, the generation of the chamfer at the beginning of the cutting gap and the depth and/or width of the chamfer to be generated. Situations may arise in which the melt is not effectively and rapidly conducted out and is jammed in the cutting gap. This may undesirably cause the melt to deposit as residue or burrs on the top side of the workpiece. On the one hand, this is detrimental to the quality of the workpiece parts with chamfered cutting edges, which in some cases, as is conventional, require costly mechanical reworking. In any case, this may increase the reject rate when producing workpiece parts with chamfered cutting edges. On the other hand, burrs deposited on the top side of the workpiece may in the worst case result in collisions with the laser machining head, which may cause damage and complicated and expensive maintenance costs and unnecessary downtime of the laser machining equipment.

Disclosure of Invention

In contrast, the object of the present invention is to improve the conventional method for producing workpiece parts with chamfered cutting edges from plate-like or tubular workpieces by means of a laser beam, so that these workpiece parts can be produced in an automated manner in a cost-effective and high-quality manner even if problems can occur due to specific movement conditions in the case of sufficiently rapid removal of the melt through the cutting gap.

These and other objects are achieved according to the proposal of the present invention by a method for manufacturing a workpiece part with a chamfered cutting edge having the features of the independent patent claims. Advantageous embodiments of the invention emerge from the features of the dependent claims.

In the sense of the present invention, the term "workpiece" refers to a plate-like or tubular, usually metallic, component from which at least one workpiece part (a pass) can be manufactured. The plate-like work is generally flat or planar. While the method of the present invention is illustrated with a single workpiece portion with a chamfered cutting edge, it should be understood that a plurality of workpiece portions with chamfered cutting edges are typically manufactured based on the workpiece.

The laser beam is guided by a laser processing head and exits at an end nozzle. The laser beam is designed as usual in the form of a focused, rotationally symmetrical beam cone with a central beam axis (symmetry axis). The beam diameter represents the lateral extent of the beam or the physical dimension of the beam perpendicular to the propagation direction. During focusing, the laser beam is concentrated by a focusing lens or a focusing mirror. The focal point of the laser beam is defined by the position at which the laser beam has its small cross-section or minimum beam diameter. Focal length means the distance of the principal plane of the lens (or principal plane of the mirror) from the focal point of the ideal, focused parallel beam. The smaller the focal length, the more focused the laser beam and the smaller the focal diameter, and vice versa.

The laser processing head is also used to guide a process gas beam which is usually, but not necessarily, discharged from the same nozzle as the laser beam and is preferably guided coaxially with the laser beam. The process gas jet emerging from the nozzle is usually, but not necessarily, designed in the form of a gas cone hitting the workpiece.

The workpiece, in particular a plate-shaped workpiece, is held against the workpiece support with the workpiece bottom side. On the top side of the workpiece, the workpiece has a (top) workpiece surface. In the case of a plate-like workpiece, the workpiece surface is flat. Unless otherwise indicated, herein and hereinafter "workpiece surface" refers to the top workpiece surface opposite or facing the nozzle. The workpiece is typically the bottom side of the workpiece with its opposite workpiece surface against the support.

The laser processing head for guiding the laser beam and the process gas beam can be moved relative to the workpiece in a generally horizontal plane parallel to the plane of the workpiece surface and in a generally vertical direction perpendicular thereto.

In the present description, the reference system is always stationary relative to the workpiece, such that the laser processing head is considered to be moving, while the workpiece is considered to be stationary. But from a local point of view it is not important whether the laser processing head, the workpiece, or both are moving. In this connection, it is likewise possible to move the workpiece instead of the laser processing head or to move the laser processing head and the workpiece simultaneously.

The energy of the laser beam depends on the specific design of the laser source and is typically given in joules (J). The power of the laser beam (i.e., energy per unit time), typically measured in joules/second (J/s) or watts (W), describes the optical output power of a continuous wave laser (CW) or the average power of a pulsed laser. Pulsed lasers are also characterized by their pulse energy, which is proportional to the average power and inversely proportional to the repetition rate of the laser. "fluence" refers to the energy of the laser beam relative to the irradiated area of the workpiece. For example, the energy density is measured in J/mm ².

In addition to the energy density, the speed of movement of the laser processing head or laser beam is also important for laser processing the workpiece, i.e. the time during which the laser beam irradiates a certain area of the workpiece. The term "energy per unit length" is generally used for this purpose. This means that the laser beam power absorbed by the laser processing head or laser beam at each speed by the workpiece is measured, for example, in watts/(mm/s). If the power watt (W) of the laser beam is given as joules per second (J/s), then the energy per unit length is measured accordingly in J/mm.

Therefore, in laser machining, the energy per unit length of the laser beam is of critical importance, wherein the energy absorbed by the workpiece depends on the energy density. At a certain laser beam power, the energy absorbed by the workpiece depends on the spot size on the workpiece, corresponding to the beam diameter at the location where the laser beam hits the workpiece. The beam diameter of the laser beam on the workpiece results from the focal position, i.e. the position of the focal point of the laser beam relative to the workpiece (shortest vertical distance), in particular relative to the workpiece surface to which the laser beam is directed or also relative to the workpiece support. If the workpiece is in the divergent region of the beam cone (the focal point is above the surface of the workpiece that the machining beam hits), the beam diameter on the workpiece can be increased by increasing the spacing between the focal point and the workpiece, and vice versa. Thus, since the beam diameter on the workpiece is changed by changing the focal position, the energy density of the laser beam and thus the energy contained in the energy per unit length absorbed by the workpiece can be changed in a targeted manner. The larger the beam diameter, the less energy is absorbed by the workpiece and vice versa. For lasers, the beam intensity (related to the cross-section) outside the focal spot is not constant. Ideally, the power intensity is gaussian. In any case, the energy density towards the edge is relatively low, especially outside the focus.

The energy per unit length also depends on the speed of the laser beam, i.e. the speed of movement of the laser processing head, which is also referred to as "feed speed". The greater the feed speed, the shorter the irradiation time of a certain area on the workpiece and vice versa. Thus, increasing the feed speed decreases the energy per unit length of the laser beam and vice versa.

It will be appreciated that the energy density, and hence also the energy per unit length, can be varied by varying the power of the laser beam itself.

Other possibilities are known to those skilled in the art to vary the energy introduced into the workpiece, particularly by varying the type and/or composition of process gases used in laser processing.

The method according to the invention for producing at least one workpiece part and a workpiece remainder from a workpiece by means of a laser beam jointly emitted from a nozzle of a laser processing head and a process gas beam for discharging molten workpiece material is designed in two stages. The method comprises a first method stage (stage I) in which a laser beam in a split mode is used and a certain section of a cutting gap and at least one local recess of the cutting gap are produced in the remainder of the workpiece. In a second method stage (stage II), the laser beam is used in a non-separating and simultaneously non-joining mode, wherein a chamfer is produced on the cutting edge of the workpiece part side of the cutting gap.

In the method according to the invention, the workpiece is thus modified in a non-separating and simultaneously non-joining manner in addition to the separating (cutting) of the workpiece to produce the cutting gap and the at least one partial recess, in order to produce a chamfer at the cutting edge of the workpiece part by means of the laser beam. The generation of chamfer is also referred to herein and hereinafter as "retrofitting" of the workpiece.

Setting the energy per unit length allows the laser beam to be selectively used for either split processing of the workpiece or non-split and simultaneously non-joining processing of the workpiece, i.e., in either split (cut) or non-split modes. In the separation mode, the energy per unit length of the laser beam is set so that the laser beam performs cutting (separation) processing on the workpiece, and thus the workpiece is penetrated, for example, to create a cutting gap. In the non-separating mode, the energy per unit length of the laser beam on the workpiece is so small that the laser beam performs non-separating and simultaneous non-joining processing on the workpiece, and thus the workpiece is not penetrated, whereby chamfering can be generated.

The change in energy per unit length of the laser beam can be achieved by changing the energy or power of the laser beam itself, by changing the feed speed of the laser processing head and/or by changing the beam diameter on the surface of the workpiece, in particular by changing the focal position relative to the workpiece. In order to change the energy introduced into the workpiece, the type and/or composition of the process gases used in the laser machining process may be additionally changed.

Preferably, the change in energy per unit length of the laser beam is performed by changing the focal position relative to the workpiece, which is preferably achieved by changing the height of the laser processing head above the workpiece or the workpiece surface towards which the laser processing head is directed, i.e. by moving the laser processing head in a generally vertical direction with a component of motion perpendicular to the workpiece surface.

Stage I of the method according to the invention comprises at least two method steps, which are referred to hereinafter for ease of reference as step a) and step b). In step a), a section of the cutting gap or the closed cutting gap is cut along the cutting line, wherein a workpiece-part-side cutting edge is formed at the workpiece part and a workpiece-remainder-side cutting edge is formed at the workpiece remainder. The cutting gap is always delimited transversely to its extension by two cutting edges facing each other, namely a cutting edge on the workpiece part side and a cutting edge on the workpiece remainder side. The cutting line follows the contour (profile) of the part of the workpiece to be produced from the workpiece. During the generation of the cutting gap, the laser processing head is moved over the workpiece, in which case the laser beam is guided along the cutting line. The cutting line is not designed on the workpiece. A cutting line is understood to mean a path along which a laser beam or a laser processing head is guided for cutting a cutting gap. The cutting gap is generated along the contour of the workpiece portion, i.e. the cutting gap is always contoured. Correspondingly, the term "cutting gap" in the sense of the invention does not include a section of the cutting gap which is not profiled and does not extend along the contour of the workpiece part. For example, during cutting of a workpiece portion, the workpiece is typically pierced away from the profile and the laser beam moves only a portion of the profiled cutting line of the workpiece portion.

In step b), at least one partial recess of the cutting gap is produced in the remainder of the workpiece by means of the laser beam.

In phase II, a chamfer is produced on the upper workpiece surface at the cutting edge on the workpiece part side by moving the laser beam along the modification line as a modification to the workpiece, provided that the workpiece part is connected to the workpiece remainder.

The laser beam is used in a split mode in phase I and in a non-split mode in phase II.

The process gas used in the laser machining process is used to remove the melted workpiece material or melt through the cutting gap, in particular when chamfering the cutting edges on the workpiece part side in phase II.

In the present invention, the contour of the workpiece portion is closed because the workpiece portion should be separated from the rest of the workpiece. According to a variant I) of the invention, in step a) of stage I, the cutting gap is not closed circularly, i.e. is not produced exactly circularly, but comprises one or more corner regions. The corner regions may be curved or rounded corner regions with rounded corners, i.e. not sharp corners. The corner region may likewise be a sharp corner region comprising two corner edges which together form a sharp corner. These two corner edges are for example shaped as sharp corners with an angle of 90 °, wherein other angles are equally possible.

In a variant i) of the invention, for the corner region of the cutting gap produced in step a), a partial depression of the cutting gap is produced in step b) in the remainder of the workpiece, so that the melt formed in the corner region during the production of the chamfer can be discharged by means of the process gas beam through the enlarged cutting gap with the partial depression and in particular also through the partial depression itself. Here, for each corner region, a separate partial depression is produced. However, it is also possible to realize that the contour or the cutting gap also has (less) curved corner regions, for which no partial depressions are produced, since the basic problem of the invention does not occur there during the production of the chamfer. The local depressions are usually designed at curved corner regions, which are curved to such an extent that there is a risk of a melt blockage occurring during the generation of the chamfer, since the melt may not be conveyed through the cutting gap with the aid of the process gas sufficiently quickly. A local depression is always provided at the sharp corner region. The cutting gap may thus have one or more curved corner regions with a partial depression respectively and/or one or more sharp corner regions with a partial depression respectively and possibly also one or more less curved corner regions without a partial depression.

According to a further variant II) of the invention, for the chamfer produced in phase II at the starting point of the production of the chamfer, which starting point can be in particular at the start of the cutting gap section, a partial depression of the cutting gap is produced in the remainder of the workpiece, so that the melt formed during the production of the chamfer can be discharged through the cutting gap widened by the partial depression.

According to a further variant iii) of the invention, in stage II the chamfer is designed such that it has a greater depth and/or width in at least one first cutting gap region than in an immediately adjacent second cutting gap region. In step b) of stage I, a partial depression of the cutting gap is then produced in the remainder of the workpiece in such a way that the melt formed in the region of the first cutting gap during the production of the chamfer can be discharged by means of the process gas beam through the enlarged cutting gap with the partial depression and in particular also through the partial depression itself.

In the method according to the invention, the variants i), ii) and iii) mentioned above can be provided separately or in any combination.

As the inventors have surprisingly found, during the generation of the chamfer, the melted workpiece material is conveyed obliquely backwards and downwards by the process gas beam through the cutting gap, i.e. the moving melt has, in addition to a vertical movement component, a horizontal movement component which is oriented counter to the direction of movement of the laser processing head for generating the chamfer. The faster the laser processing head is moved, the greater the horizontal component of motion of the melt and vice versa. Because the melt has a horizontal component of motion, the melt cannot drain through the cutting gap quickly enough in some cases. This may occur in particular when the bending of the cutting gap increases (sharp corner regions are present) or when, in general (in particular at the beginning of the cutting gap), a relatively deep chamfer should be produced, for example, which results in the melt continuously pressing against the workpiece-remaining-part-side part of the cutting edge. In some cases, the inability to effectively remove the melt through the cutting gap may also occur when the chamfer should be designed deeper and/or wider at certain locations. Depending on the specific movement conditions, such as the degree of curvature of the cutting gap and/or the speed of the movement of the laser processing head, this may lead to a blockage of the melt with the risk of burrs forming on the workpiece surface. The partial depression of the cutting gap can always ensure in an advantageous manner that the melt can be conveyed by means of the process gas jet through the enlarged cutting gap sufficiently quickly, so that melt blocking is avoided.

In stage I, step b) may be performed before, after or also during the implementation of step a). Naming does not dictate any order. Steps a) and b) can accordingly be carried out a plurality of times in succession without the need to carry out a respective further step between two like-named steps. According to a further embodiment of the method according to the invention, a plurality of steps a) are carried out before one or more steps b). According to a further embodiment of the method according to the invention, a plurality of steps b) are carried out before one or more steps a). According to a further embodiment of the method according to the invention, a plurality of steps a) and a plurality of steps b) are carried out in an alternating sequence, wherein one named step, step a) or b), respectively, is followed by the other named step, step b) or a). Preferably, step b) is performed after step a).

The chamfer at the workpiece-part-side cutting edge of the cutting gap can be produced in sections. Any order of the method steps of stages I and II is possible, provided that stage II is performed after steps a) and b) for the mentioned variants I), II) and iii).

Stage II, i.e. the chamfering, is only performed if the workpiece part is connected to the remainder of the workpiece. Essentially, after carrying out one or more steps a), the workpiece part is subsequently connected to the remainder of the workpiece by means of one or more connecting parts, in particular micro-or nano-contacts. In the sense of the present invention, a "connection" is understood to be a connection extending along a cutting line, which is formed by the workpiece material between the workpiece portion and the remainder of the workpiece, wherein the connection interrupts the cutting gap. A "microcontact" is a connection along a cutting line with a relatively small dimension which according to the invention is preferably in the range from 1/10mm to 2mm, particularly preferably in the range from 1/10mm to 1 mm. In the general use of this term, the microcontacts have a height that corresponds to the height or thickness of the workpiece (i.e., the dimension perpendicular to the surface of the workpiece). "nanocontacts" are microcontacts whose height is reduced relative to the thickness of the workpiece, wherein the height of the nanocontacts is preferably at most half the thickness of the workpiece according to the invention.

Microcontacts and nanocontacts are well known to those skilled in the art from the practice of manufacturing sheet metal workpiece parts by laser machining and from the patent literature and need not be described in detail herein. For nanojunctions, reference is made, for example, only to international patent application WO 2019025327A2.

The part of the workpiece that is connected to the remainder of the workpiece is still a fixed component of the workpiece, wherein the connection in the sense of the invention is sufficiently rigid that the position of the part of the workpiece that is partially cut away relative to the rest of the workpiece does not change or the position change that may occur therein is small and negligible during the production of the chamfer and does not lead to any change in the result that can be reasonably considered.

In order to be able to remove the workpiece part from the remainder of the workpiece, a closed cutting gap must be designed. According to the invention, the closed cutting gap is designed only after the chamfer has been produced at the cutting edge on the workpiece part side. The generation of the closed cutting gap can be carried out in a separate mode by means of a laser beam, in which case the workpiece part is severed, whereby one or more connections, in particular one or more microcontacts or nanocontacts, remain connected to the remainder of the workpiece. The workpiece part is cut off from the remainder of the workpiece. According to a design, the method of the invention comprises the following steps: the workpiece part is separated from the remainder of the workpiece in a separating mode by means of a laser beam.

The workpiece portion may be separated from the remainder of the workpiece even without the laser beam, in which case the workpiece portion is mechanically severed to thereby form one or more connections that remain connected to the remainder of the workpiece. This can be achieved, for example, by cutting or dicing (without using a laser beam) or simply by removing the workpiece portion from the remainder of the workpiece. Conventional measures for cutting micro-or nano-contacts, in particular, are well known to the person skilled in the art and need not be described here in detail. The invention therefore also includes, in particular, the case in which a single section of the cutting gap is produced by means of a laser beam, wherein the workpiece part is still connected to the remainder of the workpiece by a single connection, in particular a microcontact or nanocontact, wherein the connection is not mechanically severed by the laser beam but in other ways. According to a design, the method of the invention comprises the following steps: the complete disconnection of the workpiece part from the workpiece remainder is not achieved by means of a laser beam, but rather by means of mechanical severing of one or more connections, in particular by cutting or cutting (without the use of a laser beam) or by detaching the workpiece part from the workpiece remainder.

At least one partial depression of the cutting gap produced in the method according to the invention opens into the cutting gap or transitions into the cutting gap in the remainder of the workpiece, wherein the at least one partial depression extends from the upper workpiece surface to the lower workpiece surface, i.e. the workpiece breaks completely. The partial recess is a partial enlargement of the cutting gap. The local enlargement of the cross section of the cutting gap in the plane of the workpiece is achieved by local recessing, seen at a perpendicular angle through the workpiece. According to the invention, the partial recess is formed only partially at the cutting gap, i.e. does not extend over the entire contour of the workpiece part.

The partial recess of the cutting gap can in principle be designed in various ways, as long as it is ensured that the cutting gap is locally enlarged by the partial recess, so that the discharge of melt through the locally enlarged cutting gap is improved during the generation of the chamfer at the cutting edge on the workpiece part side.

According to an advantageous embodiment of the method according to the invention, the partial recess of the cutting gap is designed in the form of a cutting gap widening extending along the cutting gap. Preferably, the width of the cutting gap widening transverse to its extension is in particular always equal. If the corner region is designed as a curved corner region, it is advantageous if the cutting gap widening extends completely out of the curved corner region. For sharp corner areas it is then advantageous if the cutting gap widening extends around the corner and along a portion of the two corner edges, respectively. Advantageously, the cutting gap widening also extends completely over the first cutting gap region, in which a chamfer of greater depth and/or greater width is to be produced, but in which, however, it is also possible to realize: the cutting gap widening also extends into the second cutting gap region next to the first cutting gap region, as long as it is ensured that the recess is local.

The generation of such a cutting gap widening can be carried out, for example, by moving a laser processing head or laser beam along a path parallel and equidistant to the cutting line. The laser processing head or laser beam is preferably offset toward the remainder of the workpiece by a maximum of 1.5 times the beam width on the workpiece laterally of the cutting line. Advantageously, the laser beam is offset towards the remainder of the workpiece by a maximum of 1 times the beam width on the workpiece, for example by a maximum of 0.5 times the beam width on the workpiece, laterally of the cutting line. Offsetting the beam width by a factor of 0.5 widens the cutting gap, which has a width of 1.5 times that of the original cutting gap. The cutting gap widening is manufactured in such a way that no scrap part is cut from the remainder of the workpiece. The recess serving as a widening of the cutting gap is preferably produced only in the remaining part of the workpiece. The cutting gap widening is produced in a separate method step from the production of the cutting gap, wherein the cutting gap widening can preferably be formed after the production of the cutting gap, but can also be formed before it. Thus, during the generation of the cutting gap and the partial recess (cutting gap widening), the direction of movement of the laser processing head is changed at least once with respect to the direction of movement along the cutting line, so as to generate the cutting gap.

It is also possible to manufacture the cutting gap widening during the manufacture of the cutting gap. In this case, the beam diameter on the workpiece is enlarged, wherein the laser beam is maintained in a split mode. Thus, the cutting gap may be created at a greater width at certain locations. Therefore, in the process of generating the cutting gap and the partial recess, the moving direction of the laser processing head is not changed relative to the moving direction along the cutting line so as to generate the cutting gap.

According to a further advantageous embodiment of the method according to the invention, the cutting gap is designed such that it has at least one sharp corner region, wherein the partial depression in the remainder of the workpiece is designed such that it transitions into the cutting gap at the corner and at both corner edges. In the case of sharp corner areas with corners oriented with respect to the workpiece part, the partial recess is arranged inside the corner. In the case of sharp corner regions having corners oriented with respect to the remainder of the workpiece, the partial recess is disposed outside the corner.

It may be advantageous to design at least one partial depression in the sharp corner region in the form of an extension of the corner edge. Furthermore, it may be advantageous for each corner edge to have a separate partial depression of the cutting gap, wherein a common partial depression may likewise be provided for both corner edges. The partial depression may be designed in the form of an extension of the cutting gap, advantageously in the form of a linear depression, which is elongated in alignment with the corner edge. It is advantageous that no scrap portion is cut from the remainder of the workpiece during the recess generation process. It may be advantageous if the linear cutting gap extension is provided with a projection at the end, which projection is created by cutting the scrap portion from the remainder of the workpiece. It is also possible to create a partial depression in the extension of the corner edge by cutting out the scrap portion from the remainder of the workpiece.

In the method according to the invention, the laser beam is guided along a modification line in phase II for producing the chamfer. Correspondingly, the laser processing head is moved along the retrofit line. The guiding of the laser beam along the modification line does not necessarily have to be performed in such a way that the path of the laser beam coincides with the modification line. Instead, the (overall) movement of the laser beam or the laser processing head may be generated based on a secondary movement which is a primary movement and which is superimposed with the primary movement. In the (always present) primary movement, the path of the laser beam coincides with the modification line such that the laser beam is always directed towards the modification line. The secondary motion also includes a component of motion transverse (i.e., perpendicular) to the modification line so that the laser beam sweeps over a larger area of the workpiece.

If there is no secondary movement, the laser beam follows the path of the modification line to coincide with the modification line. The chamfer at the cutting edge on the workpiece part side is thus produced by directing the laser beam on a modification line, which enables particularly rapid modification of the workpiece (i.e. producing the chamfer). The (overall) movement of the laser beam then coincides with the primary movement.

However, in the method according to the invention, it may also be advantageous if the laser beam for producing the chamfer is also moved transversely to the retrofit line. In this case, the primary movement of the laser beam is superimposed on the secondary movement, wherein the laser beam performs a meandering reciprocating movement along the retrofit line according to a preferred embodiment of the method according to the invention. In this case, the laser beam is guided away from the retrofit line a plurality of times during its movement along the retrofit line and is accordingly guided back again. According to an alternative preferred embodiment, the laser beam is guided along respective closed path sections, which are preferably arranged in rows along the retrofit line. Each closed path segment is defined by the intersection of paths that the laser beam first follows. For example, the closed path segments are circular closed path segments (i.e. circles) or ellipses, which are preferably arranged in rows along the retrofit line. In this way, a chamfer of greater depth and/or width can be produced, in particular along the retrofit line. Advantageously, the movement component of the laser beam transverse to the modification line has an extension of at least 0.5mm and at most 5 mm. Preferably, the laser beam in the method has an overlap along the modification line in the range of 0.5mm to 1mm along the closed path section, in particular along a circle or ellipse. Advantageously, the overlap of the closed path segments (e.g. circles) is 0.5mm to 1mm along the retrofit line.

In the method according to the invention, it may be advantageous if, starting from at least one partial depression of the cutting gap in the corner region, the chamfer is produced by a primary movement of the laser beam along two opposite orientations of the correction line. For example, starting from at least one partial depression of the cutting gap in a sharp corner, a chamfer is produced along two opposing primary movements of the laser processing head. The sharp corners can thus be provided with workpiece-part-side chamfers in a very simple and reliable manner. However, such a movement guide can also be used advantageously for curved corner areas.

In the method according to the invention, it may also be advantageous if the partial recess of the remainder of the workpiece is arranged at least in sections, in particular completely, next to and after the starting point of the laser beam in order to produce the chamfer, with reference to the direction of the primary movement of the laser beam along the modification line in order to produce the chamfer, and with reference to a plane perpendicular to the workpiece and transverse to the direction of extension of the cutting gap. The melt which is thrown back and downward can then be transported particularly efficiently by means of the partial depression.

In the method of the invention, the partial depression of the cutting gap may generally be created without cutting the scrap portion from the remainder of the workpiece and/or from the workpiece.

In the method of the invention, the chamfer is produced by directing a laser beam along a modified line. According to a preferred embodiment of the method according to the invention, the cutting line extends parallel to a modification line for producing a chamfer on the workpiece part side, wherein the modification line is offset transversely to the cutting line. The cutting line and the retrofit line in this embodiment of the method therefore do not have the same course. The offset between the cutting line and the retrofit line is preferably at least 0.2mm and not more than 1.5mm.

In a particularly advantageous embodiment of the method according to the invention, the chamfer is also produced at the at least one connection, in particular at the microcontacts or nanocontacts. As the inventors have unexpectedly found, the connection between the workpiece part and the remainder of the workpiece is dimensioned sufficiently small along the cutting line that it only slightly interferes with the dynamic change of the process gas. This applies in particular if the connection is designed as a microcontact and has a dimension along the cutting line in the range from 1/10mm to 2mm, particularly preferably in the range from 1/10mm to 1mm.

In the production of the chamfer, it is necessary to act on the workpiece not only with the laser beam but also with the process gas beam in order to conduct the melt formed through the locally enlarged cutting gap and in particular through the local depression of the cutting gap. The pressure of the process gas should not be greater than 7bar before leaving the nozzle in order to avoid excessive material splashing onto the workpiece surface. The gas pressure is preferably between 3bar and 6bar, so that on the one hand a good removal of the melt is achieved and on the other hand material splashing can be reliably and safely avoided.

In principle, the advantageous distance between the nozzle and the workpiece or the workpiece surface depends on the process gas used. According to an advantageous embodiment of the invention, the distance between the nozzle and the workpiece surface is at least 9mm, preferably at least 20mm and particularly preferably at least 35mm in order to produce a chamfer with oxygen as process gas.

In the method according to the invention, the energy per unit length of the laser beam on the workpiece is lower in the laser processing of phase II than in phase I, which can be achieved in particular by reducing the laser beam power, increasing the feed speed of the laser processing head, defocusing the laser beam by changing the focal position relative to the workpiece (changing the beam diameter on the workpiece surface). In an advantageous embodiment of the method according to the invention, in phase II, the focal point of the laser beam is located on or above the workpiece surface. In stage II, the average laser power is preferably less than 3500W, the focal diameter of the laser beam is preferably at least 150 μm, and/or the feed speed is preferably at least 1m/min. The closer the focus of the laser beam is to the workpiece, the larger the focus diameter should be selected in phase II. Therefore, in the case where a certain focal position is on the surface of the workpiece, the focal diameter is preferably larger than 250 μm.

The method is advantageously performed in such a way that, in order to produce a chamfer at the cutting edge on the workpiece part side, the laser beam is only required to be applied to the workpiece once and is not required to be moved a plurality of times along the modification line.

In the method of the invention, one or more sections of the cutting gap are created. For example, adjacent sections of the cutting gap adjoin the connection, in particular the microcontacts or nanocontacts. However, the cutting gap may also be continuously prolonged by these sections. The modification of the workpiece is carried out along a modification line, wherein the modification of the workpiece is carried out in a relatively wide modification zone, in particular when the laser beam is also moved transversely to the modification line. It should be appreciated that the retrofit region also extends along the retrofit line.

As well as the production of the cutting gap, the modification of the workpiece (the production of the chamfer) can also be carried out in sections, i.e. the modification can be carried out in series, for example separately in sections by separating the workpiece. The modification of the workpiece can also be carried out in the region of the workpiece along the modification line (which region has no cutting gap), in particular in the region of one or more joints.

According to a further embodiment of the method according to the invention, at least two sections, preferably a plurality of sections, of the cutting gap are produced. The separating process of the workpiece is thus interrupted at least once, wherein preferably at least one connection remains between the workpiece part and the remainder of the workpiece. Preferably, the last-produced section of the cutting gap has a length measured along the cutting line that is smaller than the corresponding length of any previously-produced other section of the cutting gap. For example, from the point of free cutting of the workpiece, the length of the successively produced sections of the cutting gap does not decrease in a direction opposite to the direction of production of the cutting gap. Since the modification of the workpiece (i.e. chamfering) is only carried out when the workpiece part is still fixedly connected to the workpiece, it is possible in a particularly advantageous manner to carry out the modification of the workpiece along as large a portion of the cutting line as possible. The partially cut workpiece portion is still connected to the workpiece by the unmodified portion of the workpiece, and therefore the unmodified portion is smaller than the modified portion. Alternatively, the workpiece is also modified along the modification line where there is no cutting gap.

The modification of the workpiece (i.e. the chamfering) can take place in the region of the workpiece-part-side cutting edge that contains the cutting gap, wherein the workpiece-part-side cutting edge may likewise not be contained. For example, the first modification of the workpiece is performed in a modification zone containing the cutting edge on the workpiece portion side, and any further modification no longer contains the cutting edge. In the case of a chamfer at the cutting edge on the workpiece part side, the laser beam can be moved further into the workpiece part in the direction away from the cutting edge on the workpiece part side in a modification carried out after the first modification, in order to widen the chamfer, for example. In the case of multiple retrofitting, the retrofit region of the last retrofit may at least partially contain the retrofit region of the previous retrofit.

According to one embodiment, the distance between the modification line and the cutting line is at most half the gap width of the cutting gap, together with the radius of the beam cone of the laser beam on the workpiece surface. However, the distance between the retrofit line and the cutting line can also be greater than, for example, in the case of a multistage production of a chamfer, in which case the retrofit line is arranged farther from the cutting gap in the latter retrofit than in the former retrofit. In the multistage production of the chamfer, the modification zone contains at least the workpiece-part-side cutting edge in the case of the first modification, wherein the modification zone no longer contains this cutting edge in the case of the subsequent modification.

Advantageously, the energy per unit length of the laser beam is varied only by varying the vertical spacing of the nozzle from the workpiece surface. For example, the energy per unit length during the generation of the chamfer is less than 50%, 40%, 30%, 20%, 10% or 1% of the energy per unit length during the separation. Preferably, the beam diameter on the workpiece is less than 50%, 40%, 30%, 20%, 10% or even 1% of the beam diameter during separation during the generation of the chamfer. In the laser cutting apparatuses which are common at present, the beam diameter on the workpiece is generally 1/10 to 5/10 mm during the separation process. In order to produce a chamfer by means of a laser beam, the beam diameter on the workpiece is preferably at least 1.5 mm and lies, for example, in the range from 3 to 25 mm.

According to an advantageous embodiment of the method according to the invention, the energy per unit length of the laser beam on the workpiece is varied during the generation of the chamfer. By this measure, the depth and/or the shape of the chamfer can be specifically adjusted.

The beam axis of the laser beam is generally always oriented perpendicular to the planar workpiece support or to the plane of the irradiated upper workpiece surface in both phase I and phase II, i.e. the angle between the beam axis and the workpiece support is 90 °. This in turn brings about advantages in terms of control technology. Furthermore, technical implementation costs for the corresponding pivotability of the laser beam with respect to the workpiece support plane can be saved. However, it is also conceivable to change the beam axis during irradiation of the workpiece, wherein the beam axis forms an angle other than 90 ° with the workpiece support or with the plane of the irradiated upper workpiece surface at least temporarily. The orientation of the laser beam can be achieved by pivotability (mechanically) of the laser processing head and/or pivotability (optically) of the laser beam. For example, it may be advantageous to make the swept workpiece area larger by pivoting the laser beam during the generation of the chamfer.

The invention also extends to a laser machining apparatus having a laser beam guided by a laser machining head for laser machining a plate-like or tube-like workpiece, the laser machining apparatus having an electronic control device for controlling/regulating the laser machining of the workpiece, the electronic control device being configured (in program technology) for carrying out the method according to the invention described above.

The invention furthermore extends to a program code for an electronic control device of such a laser processing apparatus, suitable for data processing, which program code contains control instructions for driving the control device to carry out the method according to the invention.

The invention furthermore extends to a computer program product (storage medium) having stored program code for an electronic control device of such a laser processing apparatus adapted for data processing, the program code comprising control instructions for driving the control device to perform a method according to the invention.

It is understood that the above-mentioned designs of the invention may be used alone or in any combination without departing from the scope of the invention.

Drawings

The invention will now be described in detail by means of examples, reference being made to the accompanying drawings. In the drawings:

Fig. 1 shows a schematic view of an exemplary laser processing apparatus for carrying out the method of the invention for laser processing a plate-like or tubular workpiece;

fig. 2 to 16 show by way of schematic diagrams the execution of step a) of stage I and stage II of an exemplary method for laser machining a workpiece;

17-18 illustrate by way of schematic diagrams the execution of step a) of stage I and stage II of an exemplary method for laser machining a workpiece;

19-22 illustrate different exemplary designs of the non-linear movement of the laser beam along the modification line in stage II;

FIGS. 23-24 show schematic views demonstrating the generation of a chamfer in stage II;

FIGS. 25-26 show additional schematic views of chamfer creation and melt drainage in display stage II;

FIGS. 27-29 show schematic diagrams of step b) of phase I by means of an application example presentation;

FIGS. 30-31 show schematic diagrams illustrating step b) of stage I performed on a workpiece portion;

fig. 32 shows a flow chart of the method of the present invention.

Detailed Description

First of all, fig. 1 is seen, in which a laser processing device for laser cutting of a plate-shaped workpiece is shown, which is known per se. The laser processing device, generally designated by reference numeral 1, comprises a laser cutting device 2 with a laser processing head 3 and a table 4 for a workpiece 9 (which is not shown in fig. 1, see for example fig. 2 to 16) which is, for example, a flat metal plate, with a flat workpiece support 5.

The workpiece support 5 is spanned by a transverse beam 6 which is guided in a movable manner in a first axial direction (x-direction). A guide carriage 7 for the laser processing head 3 is mounted on the cross beam 6, which is guided in a movable manner on the cross beam 6 in a second axial direction (y-direction) perpendicular to the first axial direction. Thus, the laser processing head 3 can be moved parallel to and relative to, for example, a horizontal workpiece support 5 on a plane which is expanded in two axial directions (x-direction, y-direction). The laser processing head 3 is also designed to be movable up and down in a third axis direction (z direction) perpendicular to the first axis direction and the second axis direction, whereby the vertical spacing from the workpiece support 5 or the workpiece 9 can be changed. In the case of a horizontal workpiece support 5, the z-direction corresponds to the direction of gravity.

The laser processing head 3 has a nozzle 13 on its side facing the workpiece support 5, which nozzle tapers conically toward the workpiece support 5. The laser processing head 3 is used for guiding a laser beam 16 (see for example fig. 2 to 16) and for guiding a process gas beam 25 (see fig. 25 and 26). The laser beam 16 is generated by a laser beam source 8 and is guided to the laser processing head 3, for example by a beam guide tube and a plurality of deflection mirrors or optical guide cables. The laser beam 16 can be directed in a beam form (i.e. focused) towards the workpiece 9 by a focusing lens or adaptive optics. Due to the mobility of the laser processing head 3 in the first axial direction (x-direction) and in the second axial direction (y-direction), the laser beam 16 can reach any point on the workpiece 9.

The workpiece 9 has two workpiece surfaces 17, 20 (see, for example, fig. 23) opposite each other, with a first or upper workpiece surface 17 facing toward the nozzle 13 and a second or lower workpiece surface 20 facing away from the nozzle 13. Because of the upward and downward mobility of the laser processing head 3 in the z-direction, the distance between the nozzle 13 and the workpiece 9 can be adjusted by changing the distance from the upper workpiece surface 17. The spacing of the laser processing head 3 from the upper workpiece surface 17 can be adjusted before, during or after laser processing. The focal position of the laser beam 16 may be adjusted by varying the spacing of the nozzle 13 from the upper workpiece surface 17 and/or by optical elements (e.g., adaptive optics) in the laser processing head 3.

The process gas beam 25 is used to expel the melt from the slit. The process gas is generated by a gas beam generating device, not shown. For example, helium (He), argon (Ar), or nitrogen (N ₂) is used as an inert working gas. Oxygen (O ₂) is typically used as the active working gas. It is known to use mixed gases as well. The process gas has a predetermined process gas pressure (can pressure) inside the laser processing head 3, is ejected from the nozzle 13 at this pressure and is guided to the processing position coaxially with the laser beam 16.

As shown in fig. 1, the planar workpiece support 5 is formed, for example, from a plurality of support elements having, for example, support point tips of triangular design, which together define a support plane for the workpiece 9 to be machined. The support elements are embodied here, for example, as elongated support webs which extend in the y-direction and are arranged next to one another in parallel with a constant gap, for example, in the x-direction. Not shown in detail is a suction device by means of which the cutting fumes, slag particles and smaller waste parts generated during laser cutting can be sucked away.

The program-controlled control device 12 is used to control/regulate the inventive method for laser machining a workpiece 9 in the laser machining apparatus 1.

In the following, the two-stage method according to the invention is described, wherein in step a) of the first stage (stage I) a section of the cutting gap is produced and in step b) at least one partial recess of the cutting gap is produced in the remainder of the workpiece; and in a second phase (phase II) generating a chamfer at the cutting edge of the workpiece part side of the cutting gap by retrofitting the workpiece. First, step a) of stage I for producing a cutting gap and method steps of stage II for producing a chamfer are described. Step b) of stage I is described subsequently, namely the generation of at least one partial depression of the cutting gap.

Referring now to fig. 2 to 16, there are shown exemplary designs of stage I and stage II of step a) of the inventive method for laser machining a workpiece 9. Fig. 2 to 16 each correspond to the subsequent method case in this order.

First, fig. 2 is observed, wherein (dashed line) the cutting line 14 is shown. The cutting line 14 is an imaginary line which corresponds to the contour of the workpiece portion 11 to be manufactured from the workpiece 9. The contour reflects the outer shape of the workpiece portion 11. The workpiece part 11 should be cut completely out of the plate-like or tubular workpiece 9, which is not shown in detail, with the workpiece remainder 10 remaining. The workpiece part 11 here has, for example, a rectangular shape with rounded corners, wherein it is to be understood that the workpiece part 11 can have any arbitrary shape.

Fig. 3 schematically shows a laser beam 16 emitted from the laser processing head 3. The laser beam 16 is guided along the cutting line 14, wherein a cutting gap 15 is produced in the workpiece 9 at a corresponding energy per unit length of the laser beam 16 on the workpiece 9. For this purpose, the laser processing head 3 is moved to a position above the cutting line 14 in which the laser beam 16 hits the cutting position a of the cutting line 14. As shown in fig. 3, 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 the cutting position B. Thereby, a section 15-1 (solid line) of the cutting gap 15 that cuts off the workpiece 9 is generated from the cutting position a to the cutting position B. The first section 15-1 of the cutting gap 15 is created in the first section 14-1 of the cutting line 14. The laser beam 16 can also enter the workpiece 9 away from the cutting line 14, wherein the cutting gap 15 in the sense of the invention extends only along the contour of the workpiece part 11 (i.e. the cutting line 14).

In fig. 4, it is shown that the first section 15-1 of the cutting gap 15 is completely created from the cutting position a to the cutting position B. The separating process of the workpiece 9 is now interrupted. The laser beam 16 is switched off and the laser processing head 3 is moved to a modified position a' (see fig. 5) close to the cutting position a. As illustrated by the arrow in fig. 4, the displacement movement of the laser processing head 3 takes place, for example, on a straight line between the cutting position B and the retrofit position a'. The modification position a' is located on the modification line 18 for producing the chamfer. The object of the modification of the workpiece 9 is to produce the chamfer 21.

As shown in fig. 5 and further fig. 6 to 16, the retrofit line 18 is laterally offset from the cut line 14 and is arranged equidistant from the cut line. During the modification of the workpiece 9, the laser processing head 3 is moved along the modification line 18, wherein the movement of the laser processing head 3 can take place either linearly or else non-linearly along the modification line 18, as will be explained in detail below. The modification of the workpiece 9 is carried out in a modification zone 22, which has a dimension perpendicular to its extension that is generally greater than the modification line 18, which is not illustrated. The modified zone 22 is understood to be the region of the workpiece 9 modified by laser irradiation. Corresponding to the retrofit line 18, the retrofit region 22 also extends along the cut line 14. The cutting gap 15 is delimited by two cutting edges 19, 19' opposite each other (see for example fig. 23).

As shown in fig. 5, the laser beam 16 is then switched off again and the laser processing head 3 is moved along the retrofit line 18 (dashed line), wherein the laser beam 16 is moved from the first retrofit position a 'to the second retrofit position B' close to the cutting position B. In this case, the workpiece 9 is modified in the first section 22-1 of the modification zone 22.

Fig. 6 shows a situation in which the workpiece 9 has been modified along the entire first section 15-1 of the cutting gap 15. The first section 22-1 of the modified zone or modified zone 22 is schematically shown in solid lines. Similar to the sectional generation of the cutting gap 15, the retrofit region 22 is also sectional.

Starting from the cutting position B, the workpiece 9 is now further separated, as shown in fig. 6, wherein the already produced first section 15-1 of the cutting gap 15 extends into the cutting position C.

Fig. 7 shows the case where a further or second section 15-2 of the cutting gap 15 has been created along the second section 14-2 of the cutting line 14 from the cutting position B to the cutting position C. The separating process 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 retrofit position B', as shown by the arrow.

As shown in fig. 8, the laser beam 16 is now switched off 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 'towards the modification position C' close to the cutting position C.

Fig. 9 shows a situation in which the workpiece 9 has been modified in a further or second section 22-2 of the modification zone 22 between the modification position B 'and the modification position C' along the entire second section 15-2 of the cutting gap 15. The second section 22-2 of the retrofit region 22 extends the previously created first section 22-1 of the retrofit region 22.

As shown in fig. 9, the workpiece 9 is then further separated from the cutting position C, wherein the already produced part of the cutting gap 15 extends to the cutting position D.

Fig. 10 shows a situation in which a third section 15-3 of the cutting gap 15 has been created along the third section 14-3 of the cutting line 14 from the cutting position C to the cutting position D. The separating process 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 retrofit position C' of the retrofit line 18 for the subsequent retrofit. The third section 15-3 of the cutting gap 15 extends the second section 15-2 of the cutting gap 15.

As shown in fig. 11, the laser beam 16 is now switched off 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 'towards the modification position D' close to the cutting position D.

Fig. 12 shows a situation in which the workpiece 9 has been modified in the third section 22-3 of the modification zone 22 from the modification position C 'to the modification position D' along the entire third section 15-3 of the cutting gap 15. The third section 22-3 of the retrofit region 22 extends the previously created second section 22-2 of the retrofit region 22.

Starting from the cutting position D, the workpiece 9 is now further separated, as shown in fig. 12, wherein the already produced part of the cutting gap 15 extends into the cutting position E.

Fig. 13 shows the situation in which the fourth section 15-4 of the cutting gap 15 has been created along the fourth section 14-4 of the cutting line 14 from the cutting position D to the cutting position E. The separation process on 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.

The laser beam 16 is now switched off and the laser processing head 3 is moved into a position above the retrofitting position D' of the retrofit line 18 for the subsequent retrofitting.

As shown in fig. 14, the laser beam 16 is again switched off 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 'towards the modification position E' close to the cutting position E.

Fig. 15 shows a situation in which the workpiece 9 has been modified in the fourth section 22-4 of the modification zone 22 from the modification position D 'to the modification position E' along the entire fourth section 15-4 of the cutting gap 15. The fourth section 22-4 of the retrofit region 22 extends the previously created third section 22-3 of the retrofit region 22.

As shown in fig. 15, the workpiece 9 is then further separated from the cutting position E, wherein the already produced part of the cutting gap 15 extends along the fifth section 14-5 of the cutting line 14 to the cutting position a. Thereby closing the cutting gap 15 and cutting the workpiece portion 11 away from the workpiece remainder 10 so that it can be removed. Since no modification is made at the cut-off workpiece portion 11 by the method of the invention, no further modification is made to the cut-off workpiece portion 11. Here, a fifth section 15-5 of the cutting gap 15 is produced, which extends the fourth section 15-4 of the cutting gap 15.

During all separation processes, the energy of the laser beam 16 per unit length is dimensioned such that the workpiece 9 is cut off, i.e. the laser beam 16 is in a separation mode. In all modifications, the energy of the laser beam 16 per unit length is dimensioned such that the workpiece 9 is processed in a manner that neither engages nor separates, i.e. the laser beam 16 is in a non-separating mode. The beam axis of the laser beam 16 is, for example, parallel to the conical nozzle 13 and hits the workpiece 9 perpendicularly. In all separation processes and in all modification processes, the laser beam 16 is directed at the upper workpiece surface 17 with its beam axis oriented vertically unchanged relative to the upper workpiece surface 17.

The modifications can be varied in a number of ways. For example, the retrofit positions may be arranged such that the workpiece 9 is retrofit 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 section 22-1 to 22-4 of the retrofit region 22 does not extend over the entire length of the respective section 14-1 to 14-5 of the cutting line 14 or the entire length of the respective section 15-1 to 15-5 of the cutting gap 15. For example, the direction for producing the modification may also be opposite to the direction for producing the cutting gap 15.

As can be seen in particular from fig. 16, in the last (fifth) separating step a section 15-5 of the cutting gap 15 is produced, the length of which is smaller than the individual lengths of the sections produced in all the preceding separating steps of the cutting gap 15. By this measure it is advantageously achieved that as little as possible of the cutting gap 15 is not subject to modification. It is also possible that, starting from the point of separation of the workpiece part 11, the length of the part of the cutting gap 15 that occurs in these separation processes, for example, continues to increase.

The subsequent design of the method according to the invention is particularly advantageous in terms of a complete modification of the workpiece part 11. In this case, the workpiece 9 is modified along the fifth section 14-5 of the cutting line 14 between the modification positions E 'and a' after the workpiece 9 has been modified in the fourth section 22-4 of the modification zone 22, but before the fifth section 15-5 of the cutting gap 15 has been produced, i.e. before the workpiece part 11 has been cut off. This is schematically illustrated in fig. 15 by means of the joint. The fourth section 22-4 of the retrofit region 22 extends here to the retrofit position a'. The extended fourth section 22-4 'of the retrofit region 22 thus extends here to the retrofit position a' in such a way that the retrofit region 22 extends as a closed, elongated region completely over the entire contour of the workpiece part 11. In particular, in such a modification process, a chamfer can advantageously be produced at one or both of the subsequently produced cutting edges of the cutting gap 15, also in the region of the fifth section 14-5 of the cutting line 14. The workpiece portion 11 is then cut away by creating a fifth section 15-2 of the cutting gap 15.

It should be understood that the number of sections 14-1 to 14-5 of the cutting line 14 or sections 15-1 to 15-5 of the cutting gap 15 in the design of fig. 2 to 16 is exemplary and may be greater or less than this number.

An exemplary embodiment of the method is described with reference to fig. 2 to 16, in which the workpieces 9 are respectively first machined separately in an alternating sequence and the workpieces 9 are subsequently modified. It is also possible to first create different sections of the cutting gap 15, which are separated from each other by connections (in particular micro-or nano-contacts), wherein the workpiece 9 is subsequently modified. This is illustrated by means of fig. 17 and 18.

As shown in fig. 17, a further embodiment of the method according to the invention first creates three sections 15-1, 15-2, 15-3 of the cutting gap 15, which sections are separated from one another by a connection 23 (in this case, for example, a microcontact or a nanocontact). In order to produce the sections 15-1, 15-2, 15-3 of the cutting gap 15, the laser beam 16 is correspondingly introduced away from the contour of the workpiece part 11, first onto the contour of the workpiece part 11 and then along this contour. A cutting gap 15 is produced along a cutting line 14, which is not shown in detail in fig. 17. It should be understood that a greater or lesser number of sections of the cutting gap 15 may be provided along the contour of the workpiece portion 11, wherein the number of sections of the cutting gap 15 corresponds to the number of connections 23.

As shown in fig. 18, after the generation of the sections 15-1, 15-2, 15-3 of the cutting gap 15, the workpiece 9 is modified in order to generate a chamfer 21 at the cutting edge 19 on the workpiece part side, wherein the laser beam 16 is guided along the modification line 18. The modification line 18 is laterally offset and equidistantly arranged from the cutting line 14. The modification line 18 extends in particular also beyond the region of the cutting line 14 in which the connecting portion 23 is arranged, i.e. also modifies the workpiece 9 in the region of the connecting portion 23. Experiments have shown that the workpiece 9 can be modified in a sufficient manner in the correspondingly smaller-sized connection 23, since the gas dynamics of the process gas are only slightly influenced thereby.

After the workpiece 9 has been modified to produce the chamfer 21, the connection 23 is cut off, for example by means of the laser beam 16 or manually, and the workpiece part 11 is removed from the workpiece remainder 10. It is also conceivable that the connection 23 has been cut off by retrofitting the workpiece 9 in the region of the connection 23, so that the workpiece part 11 is simultaneously cut off by retrofitting. This is especially the case when the connection 23 is designed as a nano-contact with a reduced height.

The laser beam 16 is always directed along the line of cut 14 (contour) of the workpiece part 11 when the cutting gap 15 is created. When the workpiece 9 is modified, the laser beam 16 is directed either straight or non-straight along the modification line 18. In particular, the laser beam 16 may also have a movement component transverse (perpendicular) to the modification line 18 when the workpiece 9 is modified, wherein the primary movement is superimposed on the secondary movement. This is illustrated by means of fig. 19 to 22.

Fig. 19 to 22 show different exemplary embodiments of the guiding of the laser beam 16 along the retrofit line 18. For simplicity of illustration, it is assumed that the modification line 18 extends horizontally from left to right. The movement of the laser beam 16 on the retrofit line 18 corresponds to a primary movement which is superimposed with a secondary movement having a movement component transverse (perpendicular) to the retrofit line 18.

In fig. 19, a variant is shown in which the laser beam 16 is guided along closed circles 24 (i.e. closed path segments of the laser beam 16), which are arranged in rows along the retrofit line 18. After having moved through the respective circle 24, the laser beam 16 is accordingly moved linearly a distance along the retrofit line 18 and is then guided along the next circle 24. The circles 24 overlap in the direction of the modification line 18. Instead of a circle, the laser beam 16 may also be guided along an ellipse. Thus, the movement of the laser beam 16 has a component of movement that is straight along the retrofit line 18 and transverse to the retrofit line 18. By this measure, the modified region 22 produced on the basis of the area of the workpiece 9 swept by the laser beam 16 can be formed relatively widely, in particular in order to produce deep and/or wide chamfers.

Fig. 20 to 22 each show a variant in which the laser beam 16 is guided in a meandering manner along the modification line 18 in a reciprocating motion. The movement of the laser beam 16 here also includes a movement component transverse to the retrofit line 18. The meandering movement of the laser beam 16 can be rectangular in fig. 20, triangular (zigzag) in fig. 21 and sinusoidal in fig. 22. This is to be understood as merely exemplary, wherein other meandering movements of the laser beam 16 can likewise be realized. Essentially any serpentine reciprocation of the laser beam 16 along the modification line 18 may be implemented and provided in accordance with the present invention. The meandering movement of the laser beam 16 can also result in a relatively wide retrofit region 22, in particular in order to produce particularly deep and/or particularly wide chamfers.

The generation of the chamfer in stage II of the method of the invention is illustrated in fig. 23 and 24. Fig. 24 shows, by way of a perspective view, the manner in which the laser processing head 3 or the laser beam 16 is guided along the cutting gap 15 to produce the chamfer 21. As best seen in the cross-sectional view of fig. 23 (cross-section perpendicular to the plane of the workpiece 9): when the workpiece 9 is modified by the laser beam 16, the workpiece-part-side cutting edge 19 is provided with a chamfer 21 adjacent to the upper workpiece surface 17. The modification line 18 is laterally (e.g. equidistantly) offset with respect to the cutting line 14, which is not shown in fig. 23 and 24. Here, the chamfer 21 is produced, for example, by a plurality of steps or modifications, which are carried out at the same section of the cutting gap 15. In the first modification, the region of the workpiece portion 11 including the workpiece portion-side cutting edge 19 is irradiated. The modification line 18 is offset laterally (e.g. equidistantly) with respect to the cutting line 14 towards the workpiece portion 11. This can be repeated one or more times if necessary in order to produce a chamfer 21 further away from the cutting edge 19 on the workpiece part side. The workpiece-part-side cutting edge 19 is no longer irradiated jointly. It is also conceivable to first irradiate the workpiece part 11 in such a way that the region not containing the workpiece-part-side cutting edge 19 is irradiated, and then to continuously shift the retrofit line 18 in the direction of the cutting gap 15, wherein finally the workpiece-part-side cutting edge 19 is irradiated jointly. In the case of a modification of the workpiece 9 to produce the chamfer 21, the workpiece-part-side cutting edge 19 is in any case irradiated jointly in the step performed for the modification.

In particular, during the production of the chamfer 21, the laser beam 16 is advantageously moved in a meandering manner along the cutting line 14 or in a circular or elliptical manner arranged in rows, as is illustrated by means of fig. 19 to 22, whereby the width and/or depth of the chamfer 21 can be increased considerably.

In fig. 25, a section perpendicular to the plane of the workpiece 9 in the perspective view of fig. 24 is schematically shown, with the result that a chamfer 21 is produced along the cutting gap 15 at the cutting edge 19 on the workpiece part side. As is shown in a similar illustration in fig. 26, the melt 26 formed during the production of the chamfer 21 must be discharged through the cutting gap 15 by means of a process gas jet 25. Based on the movement of the laser processing head 3 or of the nozzle 13, the material of the workpiece 9 is melted obliquely during the production of the chamfer 21, which causes the melt to have a horizontal movement component counter to the direction of the movement of the laser processing head 3. The displacement movement of the laser processing head 3 along the cutting gap 15 or along the workpiece-part-side cutting edge 19 is shown by means of an arrow in fig. 25 and 26. The vertically downward directed movement component and the horizontal movement component of the melt 26 are schematically illustrated in fig. 26 by means of vector disassembly. The resulting total movement of the melt 26 is also illustrated, which causes the melt to drain downwardly and rearwardly through the cutting gap 15. The faster the speed of the moving motion of the laser processing head 3, the greater the component of the level of the melt 26 and vice versa. This may under certain movement conditions disadvantageously prevent the melt 26 from being discharged through the cutting gap 15 sufficiently quickly, resulting in its deposition as a residue on the upper workpiece surface 17. This problem may occur in particular in areas of increased bending of the cutting gap or in corner areas of the cutting gap and often where relatively deep chamfers are produced or where chamfers are produced at the beginning of the cutting gap, since the melt constantly hits the cutting edge 19' on the side of the workpiece remainder of the cutting gap 15, which may cause clogging of the melt 26. Such clogging of melt 26 may also occur when chamfer 21 is created in areas where the depth and/or width of cutting gap 15 is greater than the adjoining areas of the cutting gap.

In order to avoid this, the invention proposes to create partial depressions 27 of the cutting gap 15 at the cutting edge 19' on the workpiece-remainder side of the cutting gap, by means of which partial depressions the cutting gap 15 is enlarged, so that the melt 26 can be discharged better later, as will be explained in more detail below. The creation of such partial depressions 27 of the cutting gap 15 corresponds to step b) of stage I of the method of the invention. Stage I and stage II, step a), for example, can be carried out as described above.

Fig. 27 to 29 are first to be seen, wherein different examples of applications of the partial recess 27 of the cutting gap are shown in a schematic way. Only the creation of the partial recess 27 will be described in detail, wherein reference is made to the above-described embodiments in connection with fig. 2 to 22 for the creation of the cutting gap 15 and the chamfer 21. Corresponding reference numerals are used for the corresponding reference numerals, which are not given in the subsequent figures.

In fig. 27, the workpiece part 11 is to be cut out of the workpiece 9, which has, for example, a square contour in plan view, with curved or rounded corner regions 28. The outline or cut line 14 of the workpiece portion 11 is shown in solid lines. As schematically shown by the dashed lines in fig. 27, a chamfer 21 should be produced at the workpiece-part-side cutting edge 19 of the workpiece part 11. The curved corner region 28 is curved, for example, in a partial circle (quarter circle). The depth of the chamfer 21 is, for example, smaller than the radius of the curved corner region 28. Each curved corner region 28 of the cutting gap 15 is directly defined by a straight portion of the cutting gap 15. When the laser beam 16 is directed into the curved corner region 28, the melt 26 thrown back and downward continuously hits the cutting edge 19' on the remaining part side of the workpiece, whereby the melt 26 may become jammed.

The generation of the chamfer 21 in the curved corner region 28 is shown by means of two corner regions, here the two upper corner regions 28. To produce the chamfer 21, the laser processing head 3 is moved, for example, clockwise. The cutting gap 15 is produced in sections, wherein sections of the cutting gap 15 are produced in each case, which sections comprise curved corner regions 28. This is not shown in fig. 27. In order to ensure that the melt is always discharged through the cutting gap 15 sufficiently well when the chamfer 21 is produced in the curved corner region 28, a partial depression 27 of the cutting gap 15 in the workpiece remainder 11 is correspondingly provided at the curved corner region 28, which partial depression is embodied here in the form of a cutting gap widening along the cutting gap 15 (width enlargement of the cutting gap 15). The cutting gap widening is correspondingly designed here only in the curved corner region 28, i.e. does not extend into the adjoining straight-line portion of the cutting gap 15, but this is also possible here. The partial recess 27 is in any case only designed locally, i.e. does not extend over the entire cutting gap 15. The widened cutting gap has a constant width, i.e. the cutting gap widening has a constant dimension transversely to its extension direction. The cutting gap widening follows the cutting line 14 of the workpiece portion 11 and thus has an elongated shape. The cutting gap widening is designed only as a depression of the workpiece remainder 10, i.e. no depression is produced in the workpiece portion 11. In fig. 27, two partial recesses 27 are schematically illustrated by solid lines.

The creation of the local depression 27 at the curved corner region 28 may take place before, after or also during the creation of the section of the cutting gap 15 comprising the corner region 28. The laser beam 16 is used to create the local recesses 27 in a split mode.

For example, after the generation of the section of the cutting gap 15 comprising the corner region 28, a partial depression 27 of the cutting gap 15 is generated in the curved corner region 28. In this case, firstly a section of the cutting gap 15 is produced, which section contains the corner region 28, and subsequently a partial depression 27 is produced in the corner region 28, wherein the displacement movement of the laser processing head 3 along the cutting line 14 for producing the cutting gap 15 is interrupted at least once. For example, after the section of the cutting gap 15 is produced, the laser beam 16 is switched off, the laser processing head 3 is moved back to the corresponding position for producing the partial depression 27, the laser beam 16 is switched on again and a cutting gap widening is produced in the same direction of movement of the laser processing head 3 as the section for producing the cutting gap 15. However, it is possible to move the laser processing head 3 counter to the direction of movement of the section previously used for producing the cutting gap 15 in order to produce the partial recess 27. The partial recess 27 may also be produced before the section of the cutting gap 15 is produced.

In order to create a partial depression 27 in the form of a cutting gap widening, the laser processing head 3 or the laser beam 16 is advantageously moved parallel to the cutting line 14 and offset equidistantly. Practice has shown that an equidistant offset of 1.5 times the beam width of the laser beam can be achieved on the workpiece 9 to widen the cutting gap 15 without cutting the scrap portion from the remainder of the workpiece 10. Preferably, the laser beam is offset maximally towards the workpiece remainder 10 from the cutting line 14 by a factor of 1.5, in particular by a factor of 1, of the beam width on the workpiece 9. For example, the laser beam 16 is offset toward the workpiece remainder 10 equidistant from the scribe line 14 by a factor of 0.5 times the beam width on the workpiece 9. The enlarged width of the cutting gap 15 in the region of the cutting gap widening is then 1.5 times the unexpanded width of the cutting gap 15. A widening of the cutting gap can be produced without cutting scrap parts from the workpiece remainder 10. However, the generation of the cutting gap widening may also be accompanied by the cutting out of the scrap portion from the remainder of the workpiece 10. The laser beam 16 is moved here at a correspondingly large equidistant distance from the cutting line 14.

The chamfer 21 is produced after the local depression 27 is produced at the curved corner region 28, wherein the melt which is thrown back and down and which is formed when the chamfer 21 is produced can be discharged through the widened cutting gap 15 sufficiently quickly without the risk of clogging and the melt 26 depositing on the upper workpiece surface 17.

The four curved corner regions 28 of the exemplary profile of the workpiece portion 11 shown in fig. 27 may be provided in a similar manner with a partial recess 27 (i.e. a cutting gap widening) of the workpiece remainder 10, and then produce the chamfer 21. For example, a corresponding section of the cutting gap 15 and the partial recess 27 are produced first in the rounded corner region 28, followed by a section of the chamfer 21. It should be understood that a movement guidance can also be achieved, wherein a plurality of sections of the cutting gap 15 and/or a plurality of partial recesses 27 can be produced in any order before the chamfer 21 or sections of the chamfer 21 are produced. Likewise, the production of sections of the cutting gap 15 or of the partial depressions 27 can also be interrupted by the production of sections of the chamfer 21.

The chamfer 21 can be produced at the cutting edge on the workpiece-part side in that the laser processing head 3 or the laser beam 16 is moved in a certain direction along a retrofit line (not shown in fig. 27), which is arranged, for example, equidistant and parallel to the cutting line 14. In this regard, reference is made to the above-described embodiments in fig. 2-22.

It is also conceivable to create a local depression 27 at the curved corner region 28 during the creation of the cutting gap 15. This may be accomplished by varying (i.e., magnifying) the beam width of the laser beam 16 on the workpiece, wherein the laser beam 16 continues in a split mode. In this case, the displacement movement of the laser processing head 3 or the laser beam 16 along the cutting line 14 does not have to be interrupted, but the beam width of the laser beam 16 is only enlarged in the region in which the partial recess 27 is to be produced. In this case, a partial recess 27 of the cutting gap 15 is produced not only in the workpiece remainder 11 but also in the workpiece part 10 (good part).

A further example of the application of the partial recess 27 of the cutting gap 15 is schematically shown in fig. 28, in which, for example, the workpiece part 11, which has a rectangular contour in top view with four sharp corner areas 29, should be cut from the workpiece 9. To omit unnecessary repetition, only the differences from fig. 27 are explained and otherwise reference is made to the embodiment therein. Each sharp corner region 29 is formed by two corner edges 30, 30', which form an angle of, for example, 90 ° at a corner 31. At the four sharp-pointed corner regions 29 of the workpiece part 10, there is furthermore the risk that the melt 26 cannot be conveyed through the cutting gap 15 sufficiently quickly during the production of the chamfer 21 at the cutting edge on the workpiece part side. When the laser processing head 3 or the laser 16 is guided around the corner 31 in order to produce the chamfer 21 at the sharp corner region 29, the melt 26 thrown back and downward directly hits the cutting edge on the workpiece remainder side of the cutting gap 15, so that a blockage of the melt 16 may occur.

In order to avoid this, the partial recess 27 is cut by means of the laser beam in the separating mode on the extension of the corner edges 30, 30' in the workpiece remainder 11. The partial depression 27 is correspondingly produced in that a scrap part is cut out of the workpiece remainder 11, in this case for example a small round or disk-shaped piece, wherein it is understood that the scrap part can also have any other shape. Each partial recess 27 opens into the cutting gap 15 at a corner 31.

In order to produce the chamfer 21 in the sharp corner region 29, the laser processing head 3 or the laser beam 16 is moved along the corner edges 30, 30', starting from the partial recess 27 of the elongated corner edge 30, 30', i.e. in the sharp corner region 29, starting from the sharp corner 31, the chamfer 21 is produced with two differently oriented primary movements of the laser processing head 3 or the laser beam 16, as is shown in fig. 28. The modified line is not shown in fig. 27. The modified line is offset equidistant from the cut line 14 and parallel to the direction of the remainder of the workpiece 10. Thus, the melt 26 formed in the respective corner edge 30, 30 'during the production of the chamfer 21 can be effectively discharged through the partial recess 27 of the respective elongated corner edge 30, 30'. The generation of the chamfer 21 begins here at a starting point 36, wherein the two partial recesses 27 of the workpiece remainder 10 are arranged completely, immediately adjacent to and behind the starting point 36 of the laser beam 16, respectively, with reference to the direction of the primary movement of the laser beam 16 along the modification line for generating the chamfer 21 and with reference to a plane perpendicular to the workpiece 9 and transverse to the extension direction of the cutting gap 15, in order to generate the chamfer 21.

The two partial recesses 27 shown in fig. 28 can likewise be designed in the form of a single (shared) recess. Starting from this single depression, the generation of the chamfer 21 then takes place with two differently oriented primary movements of the laser processing head 3 or the laser beam 16 along the corner edges 30, 30'.

The procedure illustrated by means of fig. 28 can also be applied to curved corner regions 28, as is illustrated in fig. 27. The formation of the chamfer 21 in the curved corner region 28 can then take place in a similar manner to the operation in fig. 28 with two differently oriented primary movements of the processing head 3 or of the laser beam 16. Such an operation may be advantageous, for example, when the radius of the curved corner region 28 is smaller than the depth of the chamfer 21 to be produced there.

A different application situation is schematically illustrated by means of fig. 29. In one application, a relatively deep chamfer should be produced in the first cutting gap region 32 of the cutting gap 15. The first cutting gap region 32 of the cutting gap 15 is directly delimited by two second cutting gap regions 33, 33', i.e. the cutting gap 15 extends at least over the first cutting gap region 32 and the two second cutting gap regions 33, 33'. In the case of fig. 29, it is assumed that the chamfer 21 is produced by directing the laser beam 16 or the laser processing head 3 counter-clockwise, wherein the cutting gap 15 has already been formed adjacent to the starting point 36 and counter to the direction of movement, i.e. in the second cutting gap region 33'. Because of the relatively large depth of the chamfer 21 and the relatively large amount of melt 26 that is backlogged during the creation of the chamfer 21, there is a risk that the melt 26 cannot be conveyed through the cutting gap 15 sufficiently quickly. In order to avoid this, a partial depression 27 is produced in the workpiece remainder 10 at the beginning of the first cutting gap region 32, with reference to the direction of the primary movement of the laser processing head 3 or the laser beam 16 when producing the chamfer 21 (in this case, for example, counter-clockwise). The partial depression 27 is produced by cutting out a scrap portion (which here is, for example, circular or disk-shaped) from the workpiece remainder 10. By means of the partial recess 27 of the cutting gap 15, the melt 26 formed at the beginning of the chamfer 21 can be discharged quickly and effectively through the enlarged cutting gap 15 and in particular through the partial recess 27. The generation of the chamfer 21 begins here at a starting point 36, wherein the partial recess 27 of the workpiece remainder 10 is arranged immediately adjacent to and behind the starting point 36 with reference to the direction of the primary movement of the laser beam 16 along the modification line (counterclockwise) for generating the chamfer 21 and with reference to a plane perpendicular to the workpiece 9 and transverse to the direction of extension of the cutting gap 15.

In a variant, the starting point 36 of the chamfer 21 is also the beginning of the cutting gap 15. In this application case, then, no cutting gap is in the second cutting gap region 33'. In this case too, there is the risk that the melt formed during the production of the chamfer 21 cannot be conveyed through the cutting gap 15 sufficiently quickly, since the melt 26 is also thrown out to the rear without the cutting gap. Similar to the previous application, a partial depression 27 is produced at the beginning of the first cutting gap region 32, by means of which the melt 26 formed during the production of the deeper and/or wider chamfer 21 can be discharged rapidly and effectively.

In a further variant, a chamfer 21 with a greater depth and/or width should be produced in the first cutting gap region 32 than in the second cutting gap region 33' lying downstream in the direction of movement. Thus, there is a risk in the first cutting gap region 32 that: during the production of deeper and/or wider chamfers 21 at the cutting edge 19 on the workpiece-part side, the melt cannot be discharged through the cutting gap 15 sufficiently quickly. Similar to the previous application, a partial depression 27 is produced at the beginning of the first cutting gap region 32, by means of which the melt 26 formed during the production of the deeper and/or wider chamfer 21 can be discharged rapidly and effectively.

In the following, the creation of a partial depression 27 of the cutting gap 15, which is created (only) in the workpiece remainder 10, over the entire contour of the irregularly shaped workpiece part 11 is shown by means of fig. 30 and 31. Fig. 30 shows a fully cut workpiece portion 11 having an irregular profile. The workpiece portion 11 has a plurality of corner regions 28, 29 that are rounded or sharp. The chamfer 21 is produced in such a way that no change in direction occurs in the primary movement of the laser processing head 3 or the laser beam 16. The laser beam 16 is moved along a modification line (e.g. clockwise), which is equidistant and parallel here, for example, to the cutting line 14 for producing the cutting gap 15. Regarding the sectional generation of the cutting gap 15 and the generation of the chamfer 21, reference is made to the embodiments described above with reference to fig. 2 to 22. Here, only partial depressions 27 of the cutting gap 15, which are formed before the chamfer 21 is produced, should be described.

For ease of reference, corner regions are designated by letters a through G. Starting from the corner region a at the lower left in fig. 31, the different corner regions a to G are viewed clockwise. Corner region a is a curved corner region 28, which, however, is curved to a relatively small extent, so that melt 26 formed during the production of chamfer 21 can be conducted out through cutting gap 15 sufficiently quickly. The corner region a thus does not require a partial depression 27 of the cutting gap 15 to assist in the discharge of the melt 26 during the production of the chamfer 21. In contrast to this, the corner region B of the corner region 28, which is also curved, is significantly more curved, so that there is a risk that the melt 26, during the production of the chamfer 21, will clog and deposit on the upper workpiece surface 17 and form burrs there. To avoid this, a partial depression 27 in the form of a cutting gap widening is designed (only) in the workpiece remainder 10, as already explained in detail with reference to fig. 27. Reference is made to the embodiment described above with reference to fig. 27. Corner region C is a sharp corner region 29, here for example with two corner edges 30, 30' forming an angle of 90 ° at corner 31. In this case, a single (shared) recess 27 for the two corner edges 30, 30 'is produced (only) in the workpiece remainder 11, which has, for example, a rectangular shape and which merges into the cutting gap 15 in the region of the corner 31 and the two corner edges 30, 30'. Unlike fig. 28, the chamfer 21 is produced by moving the laser processing head 3 or the laser beam 16 in the same direction of movement. Corner region D is likewise a sharp corner region 29 with two corner edges 30, 30', which form an angle of, for example, 90 ° at corner 31. In this case, one of the two corner edges, namely the corner edge 30' which arrives subsequently in the displacement direction, is provided with a linear partial depression 27 which extends the alignment of the workpiece rest 11 and which is produced without the scrap part having to be cut out of the workpiece rest 11. The partial recess 27 opens into the cutting gap 15 at the corner 31 and is designed to be aligned with the corner edge 30'. However, similar to fig. 28, a partial depression of the elongate corner edge 30' can also be produced by cutting out, for example, a round scrap portion. In the case of the chamfer 21 occurring in the corner region D, the chamfer 21 is first produced in the corner edge 30 up to the corner 31. The laser beam 16 is then guided around the corner 31, wherein the melt 26 can be discharged through the partial recess 27 when the chamfer 21 is produced in the other corner edge 30'. In the two subsequent curved corner regions E and F, the respective degree of curvature is relatively small as in the corner region a, so that no local recess 27 of the cutting gap 15 is required. The corner region G, although being a curved corner region 28, has a very high degree of curvature and can be functionally regarded as identical to the sharp corner region 29 with the corner 31, which is directly delimited by the two corner edges 30, 30'. Similarly to the corner region D, the corner edge 30' which subsequently arrives in the direction of movement is provided with a partial depression 27 in the form of an aligned (straight) extension of the cutting gap 15. The partial recess 27 may be produced identically to the cutting gap 15, i.e. without a scrap portion being cut out of the remainder of the workpiece. However, similar to fig. 28, the recess of the elongated corner edge 30' can also be produced by cutting out, for example, a round scrap portion. In the embodiment of fig. 31, a linear partial depression 27 is provided at the corner region G in an elongated manner in alignment with the corner edge 30', which partial depression opens into the end-located projection 34. The end-located projections 34 are produced in such a way that, for example, circular or disc-shaped scrap parts are cut out of the workpiece remainder 10. When the chamfer 21 is generated in the corner region G, the chamfer 21 is first generated in the corner edge 30 up to the corner 31. The laser beam 16 is then guided around the corner 31, wherein the melt 26 can be discharged through the partial recess 27 when the chamfer 21 is produced in the other corner edge 30'.

Examples:

a chamfer is created at the curved corner region as shown in fig. 27. A plate material made of structural steel and having a thickness of 5mm was used as a work piece. The chamfer is 3mm deep and is produced at an angle of 45 °. The radius of the curved corner region is 6mm.

A section of the cutting gap is first created, wherein curved corner regions are included. Oxygen is used as the process gas. A cutting gap of 0.62mm in width was produced. In the next step, the cutting gap was widened 1.5 times. For this purpose, a second cut is produced at the curved corner region, which has a 0.5-fold overlap with the first cut. The width of the widened cutting gap at the curved corner region was 0.93mm. The next step is to produce chamfer. In the final step, the remaining profile (the profile portion on which no chamfer is present) is cut off with a cutting gap of width 0.16 mm.

Examples:

A chamfer is created at the curved corner region as shown in fig. 27. A plate material made of structural steel and having a thickness of 3mm was used as a work piece. The chamfer is 2mm deep and is produced at an angle of 45 °. The radius of the curved corner region is 4mm.

A section of the cutting gap is first created, wherein curved corner regions are included. Oxygen is used as the process gas. A cutting gap of 0.63mm in width is produced. In the next step, the cutting gap was widened 1.5 times. For this purpose, a second cut is produced at the curved corner region, which has a 0.5-fold overlap with the first cut. The width of the widened cutting gap at the curved corner region was 0.95mm. The next step is to produce chamfer. In the final step, the remaining profile (the profile portion on which no chamfer is present) is cut off with a cutting gap of width 0.16 mm.

In fig. 32a flow chart of a method according to the invention is shown:

Stage I

Step a) cutting the sections 15-1, 15-2, 15-3, 15-4, 15-5 of the cutting gap 15 or cutting the closed cutting gap 15 along the cutting line 14 with the laser beam 16, wherein a workpiece-part-side cutting edge 19 is formed at the workpiece part 11 and a workpiece-remainder-side cutting edge 19' is formed at the workpiece remainder 10; and

Step b) generates at least one partial recess 27 of the cutting gap 15 in the workpiece remainder 11 by means of the laser beam 16,

Stage II produces a chamfer 21 on the upper workpiece surface 17 at the workpiece-part-side cutting edge 19 by moving the laser beam 16 along the modification line 18, while the workpiece part 11 is connected to the workpiece remainder 10,

Wherein the method comprises the steps of

(I) In step a) of stage I, at least one corner region 28, 29 of the cutting gap 15 is produced, and for step b) of stage I, a partial depression 27 of the cutting gap 15 is produced in the workpiece remainder 10, so that the melt 26 formed in the corner region 28 during the production of the chamfer 21 can be discharged through the cutting gap 15 widened by the partial depression 27, and/or

(Ii) For the chamfer 21 produced in phase II at the starting point 36 of the production of the chamfer 21, wherein the starting point can be in particular at the cutting gap start 35 of the sections 15-1, 15-2, 15-3, 15-4, 15-5 of the cutting gap 15, a partial depression 27 of the cutting gap 15 is produced in the workpiece remainder 10, so that the melt 26 formed during the production of the chamfer 21 can be discharged through the cutting gap 15 widened by the partial depression 27, and/or

(Iii) In phase II, the chamfer 21 is designed such that its depth and/or width in the at least one first cutting gap region 32 is greater than its depth and/or width in the immediately adjacent second cutting gap region 33, 33', wherein a partial depression 27 of the cutting gap 15 is produced in the workpiece remainder 10, so that the melt 26 formed in the first cutting gap region 32 during the production of the chamfer 21 can be discharged through the cutting gap 15 widened by the partial depression 27.

As can be seen from the above description, the present invention provides a novel method for laser machining a plate-shaped or tubular workpiece, in which a workpiece part which has not yet been cut off is subjected to a modification along a modification line by means of a laser beam, wherein a chamfer is produced at the cutting edge on the workpiece part side. By targeted introduction of the partial depression of the cutting gap, even if a chamfer is produced in the region of a relatively sharply curved or sharp corner, the melt formed during the chamfer production can be discharged through the enlarged cutting gap without risk of clogging. The corresponding applies also when a chamfer should be produced at the beginning of the cutting gap or the chamfer should have a greater depth and/or width at certain locations. This makes it possible to dispense with mechanical reworking of the cut-off workpiece portion, so that workpiece portions with chamfered cutting edges can be produced more simply, more quickly and more cost-effectively. The reject rate in the manufacture of workpiece parts with chamfered cutting edges can be reduced. The inventive method can be implemented in a simple manner on existing laser processing equipment without complex technical measures being provided for this purpose. The method of the invention can be implemented by only intervening on the machine control system.

List of reference numerals

1. Laser processing apparatus

2. Laser cutting device

3. Laser processing head

4. Working table

5. Workpiece support

6. Cross beam

7. Guide carriage

8. Laser beam source

9. Workpiece

10. Remainder of the workpiece

11. Workpiece portion

12. Control device

13. Nozzle

14. Cutting line

14-1, 14-2, 14-3, 14-4, 14-5 Sections of cutting line

15 Cutting gap

15-1, 15-2, 15-3, 15-4, 15-5 Cutting the section of the gap

16. Laser beam

17. Upper work piece surface

18. Modification line

19, 19' Cutting edges

20. Lower workpiece surface

21. Chamfering edge

22. Retrofit region

Sections of the modified regions 22-1, 22-2, 22-3, 22-4, 22-4

23. Connecting part

24. Round circle

25. Process gas beam

26. Melt body

27. Recess in the bottom of the container

28. Curved corner regions

29. Sharp corner regions

30, 30' Corner edges

31. Corner

32. First cutting gap region

33, 33' Second cutting gap area

34. Protrusions

35. Cutting gap initiation

36. A starting point for generating the chamfer.

Claims

1. A method for producing at least one workpiece part (11) and a workpiece remainder (10) from a workpiece (9) by means of a laser beam (16) jointly emitted from a nozzle (13) of a laser processing head (2) and a process gas beam (25) for discharging a melt (26), the method comprising the following method stages:

Stage I

Step a) of cutting a section (15-1, 15-2, 15-3, 15-4, 15-5) of the cutting gap (15) or cutting the closed cutting gap (15) along a cutting line (14) by means of the laser beam (16), wherein a workpiece-part-side cutting edge (19) is formed on the workpiece part (11) and a workpiece-remainder-side cutting edge (19') is formed on the workpiece remainder (10); and

Step b) producing at least one partial depression (27) of the cutting gap (15) in the workpiece remainder (11) by means of the laser beam (16),

Phase II produces a chamfer (21) on the upper workpiece surface (17) at the workpiece-part-side cutting edge (19) by moving the laser beam (16) along a modification line (18), while the workpiece part (11) is connected to the workpiece remainder (10), wherein

(I) In step a) of phase I, at least one corner region (28, 29) of the cutting gap (15) is produced, and in step b) of phase I, a partial depression (27) of the cutting gap (15) is produced in the workpiece remainder (10) in such a way that a melt (26) occurring in the corner region (28) during the production of the chamfer (21) can be discharged through the cutting gap (15) widened by the partial depression (27), and/or

(Ii) For the chamfer (21) produced in phase II, at a starting point (36) for producing the chamfer (21), wherein the starting point can be located in particular at a cutting gap start (35) of a section (15-1, 15-2, 15-3, 15-4, 15-5) of the cutting gap (15), a partial depression (27) of the cutting gap (15) is produced in the workpiece remainder (10) in such a way that a melt (26) occurring during the production of the chamfer (21) can be discharged through the cutting gap (15) widened by the partial depression (27), and/or

(Iii) In phase II, the chamfer (21) is designed such that its depth and/or width in at least one first cutting gap region (32) is greater than its depth and/or width in an immediately adjacent second cutting gap region (33, 33'), wherein a partial depression (27) of the cutting gap (15) is produced in the workpiece remainder (10) in such a way that a melt (26) occurring in the first cutting gap region (32) during the production of the chamfer (21) can be discharged through the cutting gap (15) widened by the partial depression (27).

2. Method according to claim 1, wherein the partial recess (27) of the cutting gap (15) is designed in the form of a cutting gap widening extending along the cutting gap (15), which cutting gap widening has a width that is in particular always equal transversely to its direction of extension.

3. The method according to claim 2, wherein the corner region of the cutting gap (15) is a curved corner region (28), wherein the cutting gap widening extends completely over the curved corner region (28).

4. The method according to claim 1, wherein the corner region of the cutting gap (15) is a sharp corner region (29) with two corner edges (30, 30 ') forming a corner (31), wherein a partial recess (27) is designed in the workpiece remainder (10) such that it transitions into the cutting gap (15) at the corner (31) and at both corner edges (30, 30').

5. Method according to claim 1 or 4, wherein the corner region of the cutting gap (15) is a sharp corner region (29) with two corner edges (30, 30 ') forming a corner (31), wherein at least one partial recess (27) is designed in the form of an extension of a corner edge (30, 30').

6. The method according to claim 5, wherein the at least one partial recess (27) is designed to be rectilinear and elongated in alignment with the corner edge (30, 30').

7. Method according to claim 6, wherein the partial recess (27) which is designed in a straight line and in alignment with the corner edge (30, 30') is provided with a projection (34) at the end.

8. Method according to one of claims 1 to 7, wherein, starting from at least one partial recess (27) of the cutting gap (15) in the corner region (28), the chamfer (21) is produced by two differently oriented primary movements of the laser beam (16) along the retrofit line (18).

9. Method according to one of claims 1 to 8, wherein the partial recess (27) of the workpiece remainder (10) is arranged at least in sections, in particular completely, next to and behind a starting point (36) of the laser beam (16) for producing the chamfer (21), with reference to the direction of the primary movement of the laser beam (16) along the modification line (18) for producing the chamfer (21), and with reference to a plane perpendicular to the workpiece (9) and transverse to the direction of extension of the cutting gap (15).

10. Method according to one of claims 1 to 9, wherein in phase II for producing the chamfer (21), for the laser beam (16):

i) Directing the laser beam only along the same path as the retrofit line (18), and/or

Ii) moving the laser beam (16) with a primary movement superimposed with a secondary movement, wherein the primary movement extends only along the modification line (18) and the secondary movement also has a movement component transverse to the modification line (18), wherein the laser beam (16) in particular executes a meandering reciprocating movement and/or moves the laser beam along a closed path section, in particular a closed circle (24) or an ellipse, which is arranged along the modification line (18).

11. Method according to one of claims 1 to 9, wherein the local recess (27) of the cutting gap (15) is produced by and/or without cutting off a scrap part from the workpiece remainder (11).

12. The method according to one of claims 1 to 11, wherein the local recess (27) is produced only in the workpiece remainder (11).

13. A beam machining device (1) with a machining beam (14) guided by a beam head (3), having an electronic control device (12) for controlling beam machining of a workpiece (9), which is configured in program technology for carrying out the method according to one of claims 1 to 12.

14. Program code for an electronic control device adapted for data processing of a beam processing apparatus (1) according to claim 13, the program code comprising control instructions for causing the control device (12) to perform the method according to one of claims 1 to 12.

15. A computer program product having stored program code for an electronic control device of a beam machining apparatus (1) according to claim 13, suitable for data processing, the program code comprising control instructions for causing the control device (12) to perform the method according to one of claims 1 to 12.