Method for cutting at least one workpiece out of a sheet metal

Abstract

The invention relates to a method for cutting out at least one workpiece (12) from a thin plate (6), comprising the steps of A) placing the thin plate (6) on a table (4) of a laser cutting machine, B) directing a laser beam at the thin plate (6) along a finish line (19) of the workpiece (12), in order to cut the thin plate (6) in a main area of ​​the finish line (19) and to leave at least one joint (14) having a height smaller than the thickness of the thin plate (6) in at least one joining area of ​​the finish line (19) between the workpiece (12) and an adjacent part (13) of the thin plate (6), C) removing the at least one workpiece (12) and the adjacent part (13) joined to the workpiece (12) from the table, and D) separating the at least one workpiece (12) from the adjacent part (13).

Description

[Technical field]

[0001] 2. Background of the Invention The present invention relates to a method for cutting out at least one workpiece from a sheet of metal placed on the table of a laser cutting machine.

[0002] The laser cutting method for cutting out workpieces from a sheet metal is basically known. The sheet metal is typically placed on the table of a laser cutting machine for cutting out the workpieces. This table often has a number of tabs spaced apart from one another, so that the sheet metal is not supported over its entire surface. There is therefore a risk that especially smaller workpieces will tip over after cutting out, which makes it impossible to automatically remove the workpieces or that the workpieces will become stuck in the scrap skeleton of the sheet metal.

[0003] From US 2018 / 0093348 it is known to cut out a workpiece only partially, so that it remains connected to a scrap skeleton unit. This scrap skeleton unit is completely separated from the sheet metal, so that the scrap skeleton unit can be removed including one or more components connected to it. To obtain a joint between the respective workpiece and the scrap skeleton unit, the laser beam is interrupted. This means that the sheet metal is no longer exposed to the laser beam in the area of ​​the joint and is therefore no longer processed.

[0004] The joints obtained by the method described in US 2018 / 0093348 A1 extend over the entire thickness of the sheet. Such joints are also called "micro-joints". Due to the height of the joints, including the entire thickness of the sheet, it is laborious to separate the workpiece from the respective scrap skeleton unit. Furthermore, after the laser beam is interrupted to produce the joints, the sheet must be pierced again. On the one hand, this is time-consuming. On the other hand, direct piercing of the workpiece usually leads to a local reduction in the cutting edge quality. Therefore, direct piercing of the workpiece is often not allowed.

[0005] Problem to be solved by the invention The object of the invention is to provide a method with which qualitatively high-value sheet metal workpieces can be produced rationally, particularly reliably, in a process which can be automated and is simple.

[0006] Description of the invention This problem is solved according to the invention by a method having the features set forth in claim 1. Advantageous method variants are set forth in the dependent claims and the description.

[0007] According to the invention, a method is specified for cutting at least one workpiece out of a sheet metal. The sheet metal typically consists of metal. The sheet metal may in particular consist of steel. The sheet metal may have a thickness of at least 2 mm, in particular at least 4 mm. The sheet metal may have a thickness of at most 40 mm, in particular at most 30 mm.

[0008] The method is: A) placing a sheet of metal on a table of a laser cutting machine; B) directing a laser beam along the finish line of the workpiece to the sheet metal, cutting the sheet metal in a main area of ​​the finish line and leaving at least one joint area of ​​the finish line between the workpiece and an adjacent part of the sheet metal, the joint having a height smaller than the thickness of the sheet metal; C) removing at least one workpiece and an abutment coupled to the workpiece from the table; D) separating the workpiece from adjacent pieces; Contains:

[0009] Steps A) to D) are essentially performed in the order described.

[0010] In step A), the sheet metal is placed on the table of the laser cutting machine. The sheet metal may be fixed in position on the table, which typically has various restraining means for locally restricting and restraining the sheet metal, for example tabs extending parallel and spaced apart from one another.

[0011] In step B), a laser beam is directed at the sheet metal. This laser beam may be emitted from a processing head of a laser cutting machine. The point of impact of the laser beam on the sheet metal is moved along the finish line of the workpiece. For this, the processing head may be moved relative to the table. Together with the laser beam, a cutting gas jet, for example nitrogen and / or oxygen, may be directed at the sheet metal along the finish line. The laser beam and the cutting gas jet may issue together from a cutting gas nozzle of the processing head. The finish line corresponds to the outer contour of the workpiece. The movement along the finish line may be performed closed (without interruption) or in several sections separated in time. During the movement along the finish line, the laser beam is not switched off as a rule. Material is removed everywhere along the finish line.

[0012] In the main area of ​​the finishing line, the sheet metal is cut off. The main area typically comprises more than 90%, preferably more than 95%, particularly preferably more than 98% of the length of the finishing line. In at least one joining area of ​​the finishing line, at least one joint is left between the workpiece and the adjacent part of the sheet metal, which has a height smaller than the thickness of the sheet metal. In the following, such a joint is also called "nano joint" or "small height joint". This joint is essentially formed on the side of the sheet metal opposite the impact point of the laser beam. In other words, at least one workpiece remains joined to at least one other workpiece or scrap skeleton part. The joint does not extend over the entire thickness of the sheet metal or workpiece. The joint with the adjacent part can prevent the workpiece from tipping over.

[0013] Preferably, the laser power is reduced in the joining area of ​​the finish line, which results in a joint with a small height. Alternatively or additionally, the cutting speed may be increased or the distance between the cutting gas nozzle, which directs the laser beam and the cutting gas jet to the sheet or workpiece, may be increased. These parameter changes locally limit and avoid complete cutting of the sheet. The implementation of parameter changes to form joints with a small height may be performed as described in WO 2019 / 025327. Please refer to the description in WO 2019 / 025327. However, the joints referred to herein as joints with a small height or "nano joints" are referred to as "micro joints" in WO 2019 / 025327.

[0014] In step C), at least one workpiece is removed from the table together with the adjacent part, which is connected to the workpiece via at least one connection of small height. Due to the connection of the at least one workpiece with the adjacent part, this can be done particularly simply. The removal device does not have to act on each workpiece, but only on one suitable point or possibly on several suitable points of the composite. The number of points of action is typically less than the number of workpieces to be removed together. This accelerates the removal process. The removal device can have a vacuum gripper, a magnetic gripper, a Bernoulli gripper and / or a mechanical gripper, in particular a parallel gripper. By means of the nano joints, on the one hand, the workpieces can be held sufficiently tightly to each other or to the scrap skeleton part, and on the other hand, they can nevertheless be easily separated from each other or from the scrap skeleton part, for example by hand.

[0015] Then, in step D), at least one workpiece is separated from the adjacent part. In other words, the workpiece is individualized. Due to the small height of the joint, the separation can be carried out particularly simply and with particularly low force consumption. Furthermore, due to the small height of the joint, the separated workpieces have sufficiently undamaged edges, i.e. workpieces with good quality. The separation can be carried out manually, for example by pushing with a finger or by hitting with a hammer. Preferably, the separation is carried out in an automated manner. If several workpieces are removed together, the separation of several workpieces can be carried out in one work step. This further accelerates the method. The separation can be carried out by shaking, pressing, blowing or suction, in particular magnetic or vacuum suction. By shaking, in this case, in particular multiple back and forth movements are meant. When shaken, at least one impact can be introduced into the composite.

[0016] A separation device for separating the workpiece from the part connected to it via the nanojoint can be formed in the removal device, in particular integrated in the removal device. Alternatively, the removal device and the separation device can be provided separately from each other. The separation device can be, for example, a push-out device with a push-out pin, which is movable, in particular by a pneumatic cylinder. For separation by shaking, a separate separation device is not necessarily required. The composite connected via a joint of small height can be shaken, for example, by the removal device, whereby at least one workpiece is released from the adjacent part. In the process, the nanojoint is torn open.

[0017] For singulation, the removal device may be run over the finished product tray with the composite including the workpiece. After singulation, the good parts are located on or in the finished product tray. The possibly remaining scrap skeleton part may be lowered into a separate tray.

[0018] The method according to the invention further has the advantage that the cutting gap, in which the nanojoints are arranged, can be very narrow. In particular, if several workpieces have a common separation cross section and are to be held together by joints as a composite on the table (without the individual parts tipping over), this can only be achieved via nanojoints. When forming the microjoints (extending over the entire thickness of the sheet or workpiece), the laser beam must be switched off, so that afterwards, for further cutting between the workpieces, a direct piercing must be carried out on the good part. This is usually not possible. A narrow cutting gap further has the advantage that the vacuum sucker (vacuum gripper) of the removal device does not necessarily have to act on scrap skeleton areas without cutting lines or on sufficiently large workpieces, and can extend beyond the cutting gap without the suction action becoming too small. In this way, it is not necessarily necessary to provide a special area for sucker positioning.

[0019] The height of the joint of small height may be at most 1 / 3, preferably at most 1 / 4, particularly preferably at most 1 / 6 of the thickness of the sheet. Typically, the height of the joint is at least 1 / 20, in particular at least 1 / 10 of the thickness of the sheet. The length of the joint of small height, measured along the finish line, may be at most half and / or at least 1 / 8, in particular at least 1 / 4 of the thickness of the sheet. The joint dimensioned in this way allows the workpieces to be held securely on the one hand and easily singulated on the other hand.

[0020] In an advantageous method variant, in step B), a group of workpieces is formed which are connected to one another via a joint of small height at at least one common finishing line of the workpieces. In other words, the workpieces have a common cutting edge. At least one nanojoint is then arranged at each common cutting edge. Such a group of workpieces is sometimes called a "nested". This variant makes use of the fact that no new piercing is required after the creation of the joint of small height. The joint can therefore be formed between two workpieces (good parts). Furthermore, the common finishing line allows a particularly space-saving arrangement of the workpieces on the sheet metal.

[0021] The group of workpieces may have an outer finish line extending over the entire circumference, which is formed by the finish lines of the workpieces along which the sheet metal is cut. In other words, this outer finish line may be formed by the main area of ​​the finish lines of the workpieces. In this way, a "nest" of workpieces connected to one another is obtained, which is entirely separated from the scrap skeleton. The group of workpieces (nest) may be removed from the sheet metal as a unit, i.e. without any scrap skeleton parts as ballast.

[0022] In step C), a removal device may act on one workpiece of the group. Since the support force of the removal device is limited, more workpieces (good pieces) can thus be removed together in one step. The maximum part weight for a nest is preferably 100 kg. The maximum size of the nest may be 1000 mm x 1500 mm.

[0023] In step B), in addition to the at least one workpiece, at least one sheet section is cut out from the sheet, which sheet section can be removed individually in step C) independently of the at least one workpiece and its adjacent sections, thereby allowing flexible use of the sheet for producing, in particular, large sheet sections which do not need to be fixed in position and can be handled individually, and smaller or elongated workpieces which need to be fixed in position and are preferably removed in a composite.

[0024] In an advantageous method variant, in step B), a group of workpieces is formed, which are each connected to a common scrap skeleton part via at least one connection of small height. In step C), the workpieces and adjacent scrap skeleton parts can be removed together. This variant is particularly suitable for small workpieces that cannot be arranged directly adjacent to one another.

[0025] Preferably, prior to step C), the scrap skeleton parts are cut off from the sheet, in particular along a contour that extends over the entire circumference. If the scrap skeleton parts are arranged on the edge of the sheet, the contour for cutting off may extend between the edge points of the sheet. The contour may be concave. In this way, the (in particular smaller and / or elongated) workpieces that continue to be connected to the scrap skeleton parts by nanojoints can be distributed in the sheet between larger workpieces or sheet parts that do not need to be stabilized by nanojoints and surrounded by a continuous cutting line along the contour. The shape of the contour surrounding the workpieces of a group can be selected virtually freely. In particular, scrap skeleton parts that differ from a square, in particular scrap skeleton parts that differ from a rectangle, can also be cut off from the remaining sheet. In this way, a material-efficient nesting of the workpieces is possible. The arrangement of the smaller workpieces may depend on the space available in the sheet between the larger sheet parts. In this case, the contour surrounding the group of workpieces is selected accordingly. In other words, a scrap skeleton part is formed which may have any shape, not necessarily rectangular, surrounding the workpieces, and which is then cut away from the sheet metal and removed together with the workpieces contained therein.

[0026] The minimum distance of the contours from the workpieces of the group may be at least 12 mm. Preferably, the minimum distance is greater than the thickness of the sheet metal, especially if the thickness of the sheet metal is greater than 15 mm, so that the scrap skeleton parts can be prevented from swelling due to the heat input of the laser cutting.

[0027] The scrap skeleton part may have working surfaces for the grippers of the removal device, in particular for the vacuum grippers, on which essentially no cutting lines are machined. Particularly preferably, at least one working surface for the removal device with a diameter of at least 120 mm is left on the scrap skeleton part without a workpiece, which also allows for reliable handling of larger composites.

[0028] In step C), the scrap skeleton part may be acted upon by an unloading device, which simplifies removal of very small workpieces. Furthermore, damage to the workpieces by the unloading device is avoided. If the separation of the workpieces from the scrap skeleton part takes place while the unloading device is acting on the scrap skeleton part, it can be checked by measuring the weight held by the unloading device whether all the workpieces have been released from the scrap skeleton part.

[0029] Preferably, the scrap skeleton portion is greater than or equal to 30 mm x 80 mm and less than or equal to 1000 mm x 1500 mm. A scrap skeleton portion dimensioned in this way can be easily removed by an automated removal device. The maximum weight of the scrap skeleton portion and the workpieces held on it is preferably a maximum of 100 kg.

[0030] The scrap skeleton part and the workpieces contained therein and connected to it via nanojoints can be placed on the edge of the sheet metal, so that the previously normally unused remaining edge of the sheet metal (typically 10 mm edge width) can be used on the one hand for fixing the workpiece for removal and on the other hand as a point of application for the removal device.

[0031] If the removal device for removing the composite acts on a workpiece, it is advisable to provide this workpiece with at least two nanojoints on opposite sides, so that the weight of the composite to be removed is distributed over at least two nanojoints, thereby reducing the risk of premature fracture of the nanojoints.

[0032] The point of application of the removal device is preferably positioned such that the composite to be removed does not tip over during removal. The point of application may be located at the center of gravity of the composite. In this case, one gripper is in principle sufficient. The two points of application may be located at opposite corners of the composite or on opposite sides of an axis passing through the center of gravity of the composite. In these cases, at least two grippers are required.

[0033] The table for the thin plate may have tabs extending parallel to one another. In this case, a workpiece narrower than the distance between two adjacent tabs of the table acquires at least two joints of small height when the short side of the workpiece is oriented transversely to the tab. In other words, two nanojoints are provided when the long side of the workpiece extends (almost) parallel to the tab. The workpiece is typically at least 100 mm long. If an elongated workpiece is cut out in a position with a risk of tipping, the elongated workpiece is stabilized by at least two nanojoints. Preferably, a first joint of the joints of small height is arranged on the short side of the workpiece. Particularly preferably, a second joint of the joints of small height is arranged on the long side of the workpiece, in particular at a distance from the first joint by at least 60% of the length of the workpiece. In this way, the workpiece can be effectively stabilized. In particular, sagging of the workpiece, which may make removal difficult or impossible, can be avoided.

[0034] The separation in step D) can be performed while the removal device used for the removal in step C) holds the workpieces indirectly or directly. This can reduce the expenditure on devices for singulating the workpieces. In particular, if the removal device shakes the composite with the workpieces for separation, additional devices for separating the workpieces from adjacent parts can be dispensed with. The ejection of the workpieces ("pin eject") can also be easily performed while the removal device holds the composite with the workpieces. A movable ejection pin can be arranged on the removal device, in particular on the gripper of the removal device.

[0035] Alternatively, the separation in step D) can take place after the removal device used for the removal in step C) has released the workpieces, in particular after lowering them into the separation device. This variant is particularly suitable for groups of workpieces that do not contain scrap skeleton parts in the composite. The separation device can sort the workpieces for further processing.

[0036] Further features and advantages of the invention will become apparent from the claims, the description and the drawings. According to the invention, the features mentioned above and described below may each be used individually alone or in any advantageous combination. The embodiments shown and described in the drawings should not be interpreted as a limiting enumeration, but rather as exemplary features for the purpose of illustrating the invention.

[0037] Detailed description of the invention and drawings The invention is illustrated in the drawings and will be explained on the basis of examples. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 illustrates a laser cutting machine configured to perform a laser cutting method according to the present invention. [Figure 2a] FIG. 1 is a top view of a workpiece laser cut from a sheet of metal and held in adjacent pieces by nanojoints. [Figure 2b]2b-IIb in FIG. 2a, a cross-sectional view of a workpiece laser cut from a sheet metal and held in adjacent pieces by nanojoints. [Diagram 3] FIG. 2 shows a schematic plan view of a thin plate with four groups of workpieces connected via nanojoints to a common scrap skeleton part of one of the groups, during the method according to the invention. [Figure 4] FIG. 1 shows a schematic plan view of a sheet metal with two groups of workpieces connected via nanojoints to a common scrap part of one of the groups and further individual cut-out sheet metal parts during the method according to the present invention. [Diagram 5] FIG. 1 shows a schematic plan view of another sheet metal with two groups of workpieces connected via nanojoints to a common scrap part of one of the groups and with another individual sheet metal part cut out during the method according to the present invention. [Figure 6] FIG. 2 shows a schematic plan view of a thin plate with a group of workpieces connected to each other via nanojoints during the method according to the invention. [Figure 7] 1 is a schematic flow chart of a method according to the present invention;

[0039] The laser cutting machine 1 shown in a perspective view in FIG. 1 has, for example, a CCV laser, a diode laser or a solid-state laser as a laser beam generator 2, a mobile (laser) processing head 3 and a table 4. A laser beam 5 is generated in the laser beam generator 2, which is guided from the laser beam generator 2 via a light guide cable (not shown) or a deflection mirror (not shown) to the processing head 3. A sheet metal 6 is arranged on the table 4. The laser beam 5 is directed to the sheet metal 6 by means of focusing optics arranged in the processing head 3. The laser cutting machine 1 is further supplied with cutting gases 7, for example oxygen and nitrogen. The use of the respective cutting gas 7 depends on the material of the sheet metal 6 and on the quality requirements imposed on the cut edge. Furthermore, a suction device 8 is provided. This suction device 8 is connected to a suction channel 9 located below the table 4. The cutting gas 7 is supplied to a cutting gas nozzle 10 of the processing head 3 and leaves from this together with the laser beam 5.

[0040] During laser cutting, the sheet metal 6 is cut by the laser beam 5 along the desired trajectory curve K, which is part of the finish line of the workpiece to be cut out, with a higher laser power (cutting power) sufficient to cut the sheet metal. In the illustrated configuration, the laser beam 5 is moved, however, alternatively or additionally the sheet metal 6 can also be moved. For this, the sheet metal 6 must first be pierced at a point S on the trajectory curve K to be cut or to the side of the trajectory curve K to be cut, as shown in FIG. 2a.

[0041] 2a and 2b, when the sheet metal 6 is laser-cut, connections 14a, 14b in the form of tabs or nano-joints are left in the cutting gap 11 between the workpiece 12 to be laser-cut and the adjacent part 13 of the sheet metal 6. These connections 14a, 14b fix the workpiece 12 to the adjacent part 13 and thus prevent it from tipping over relative to the adjacent part 13 or to the table 4. Furthermore, due to the connections 14a, 14b, the workpiece 12 and the adjacent part 13 can be handled as a composite.

[0042] As shown in Fig. 2b, the nano-joints 14a, 14b do not extend over the entire thickness D of the sheet 6, but only over the lower third, i.e. they have a height d less than the thickness D. Thus, in this specification, the nano-joints are also referred to as small height joints 14a, 14b. The length L of the nano-joints 14a, 14b is less than the thickness D along the cutting gap 11. Preferably, the length L of the nano-joints 14a, 14b is less than half the thickness D.

[0043] 2a, the nano joint 14a is located at the end of the cut, i.e. it is formed just before the start point S of the self-closed trajectory curve K is reached again. In contrast, the nano joint 14b is not located at the end of the cut, but at any part of the trajectory curve K. In this specification, the length range of the trajectory curve K where the nano joints 14a, 14b are formed is also referred to as the joining range of the finish line 19 of the workpiece 12. Moreover, the length range of the trajectory curve K where the thin plate 6 is completely cut is also referred to as the main range of the finish line of the workpiece 12.

[0044] The creation of the joints 14a, 14b is explained below by the example of changing the laser power. In this variant of the method, the nanojoints 14a, 14b are formed only by precisely adapting the laser power during the cutting process with a suitably selected power gradient. The power gradient is preset by the control device 15 of the laser processing machine 1 shown in FIG. 1 depending on the workpiece material. The control device 15 also controls the movement of the processing head 3 relative to the sheet metal 6. The reduced laser power no longer provides the cutting process with the section energy required for a complete cut, so that the material is not melted over the entire thickness D of the sheet metal 6, but nanojoints 14a, 14b remain between the workpiece 12 to be laser cut and the adjacent part 13 in the cutting gap 11 or in the area below the cutting edge.

[0045] Apart from the laser power, all other cutting parameters of the laser cut remain unchanged during the formation of the nano-joints 14a, 14b, i.e. for example the focus position of the laser beam 5, the distance of the cutting gas nozzle 10 to the workpiece surface, the cutting gas pressure and the cutting speed. After the formation of the nano-joints 14b, the cutting continues with standard parameters. After the formation of the nano-joints 14a, the laser beam 5 can be switched off. Alternatively, a further workpiece can be cut out.

[0046] In order to form nano-joints 14b that are not located at the ends of the trajectory curve K and have a height d less than the workpiece thickness D, during laser cutting of the thin plate 6, the laser power of the laser beam 5 is reduced in the portion of the trajectory curve K corresponding to the length L of the nano-joint 14 from a higher laser power (cutting power) sufficient to cut the thin plate 6 to a lower laser power (reduced power) that is not sufficient to completely cut the thin plate 6, and then increased again to the higher laser power (cutting power). During processing with the low laser power (reduced power), recesses are formed in the thin plate 6 above the nano-joints 14a, 14b.

[0047] FIG. 3 shows a sheet metal 6 in which four groups 16 of workpieces 12 have been cut out. Each group 16 comprises a number of workpieces 12 and a scrap skeleton portion 17 which constitutes an abutment 13 for the workpieces of the group 16. All workpieces 12 of a group 16 may be of the same shape. Alternatively, a group 16 may comprise different workpieces 12. The workpieces 12 of a group 16 are respectively connected to a corresponding scrap skeleton portion 17 via at least one nano-joint 14 (illustrated abstractly by a checkerboard pattern). Naturally, the joints 14 are made smaller in practice than is shown diagrammatically in FIG. 3 for reasons of clarity. The scrap skeleton portions 17 are cut off from the sheet metal 6 along a contour 18 which respectively runs over the entire circumference. The scrap skeleton portions 17 are exemplarily rectangular in FIG. 3.

[0048] The workpieces 12 may have a cut inner contour 20 inside their respective finish lines 19. If the area encompassed by this inner contour 20 is large enough, it is possible to cut out another smaller workpiece inside the inner contour 19 and join it to the workpiece 12 via a nano-joint (not shown).

[0049] The scrap skeleton parts 17 may be provided with a number of working surfaces 21 for grippers of a removal device (not shown). These working surfaces 21 may have a diameter, for example, greater than 120 mm. In the illustrated configuration, the working surfaces 21 are arranged at the corners of the scrap skeleton part 17. No cutting lines are provided within the working surfaces 21. A vacuum gripper can therefore suck up the scrap skeleton part 17 in the area of ​​the working surfaces 21. Each scrap skeleton part 17, including the workpieces 12 held on it, can then be removed from the remaining scrap part 30 of the sheet metal 6.

[0050] To separate the workpieces 12, the removal device can vibrate or oscillate (rapidly move back and forth) each scrap skeleton part 17. Due to the dynamic loads that are generated in this way, the connections 14 are broken. The workpieces 12 can fall out of the scrap skeleton part 17 and be collected, for example, in a collection vessel. The weight loss of the workpieces 12 during release can be measured by the removal device, which makes it possible to check whether the separation has been completed.

[0051] In Fig. 4, a sheet 6 is shown in which a number of larger sheet parts 22 and two groups 16 of a number of smaller workpieces 12 are cut out. The sheet parts 22 are completely separated from each other and are each removed individually. The workpieces 12 of both groups 16 are connected to respective scrap skeleton parts 17a, 17b via nano-joints not shown in Fig. 4 (see the above explanation for Fig. 3). The scrap skeleton parts 17a, 17b may also have working surfaces 21 for grippers of a removal device.

[0052] The contour 18 extending all around the scrap skeleton part 17a located at the bottom right of Fig. 4 is rectangular. The two working surfaces 21 may be provided at the corners located opposite each other.

[0053] The scrap skeleton part 17b on the left side of Fig. 4 has a complex contour 18. Here, the scrap skeleton part 17b is approximately C-shaped and has a concave section. The working surfaces 21 may be provided in the end regions of three sides of the C-shape.

[0054] The arrangement of the workpieces 12 connected via nanojoints to the respective scrap skeleton parts 17a, 17b within the group 16 is selected in the illustrated configuration in such a way that the area of ​​the sheet metal 6 is used as fully as possible for the production of the sheet metal parts 22 and the workpieces 12. The contours 18 extending over the entire periphery of the scrap skeleton parts 17a, 17b are selected in such a way that the workpieces 12 are advantageously grouped together within the group 16.

[0055] 5 shows a sheet 6 resting on parallel extending tabs 23 on a table 4 of a laser cutting machine 1 (see FIG. 1). The two larger sheet portions 22 have been completely separated. Additionally, two groups 16 of workpieces 12 are illustrated.

[0056] The group 16 shown in the lower left part of Fig. 5 comprises, for example, two small workpieces 12. These workpieces 12 are connected via one nano-joint 14 in each case to a scrap skeleton part 17c. This scrap skeleton part 17c is arranged directly on the edge of the sheet metal 6. A contour 18 of the scrap skeleton part 17c extends between the two outer faces of the sheet metal 6. The edge side area of ​​the scrap skeleton part 17c can be used as a working surface for handling the composite of the two workpieces 12 and the scrap skeleton part 17c.

[0057] The group 16 shown on the center right of FIG. 5 comprises, for example, two elongated (elongated) workpieces 12. These workpieces 12 are connected to the scrap skeleton part 17d via two nanojoints 14 in each case. The short sides 24 of both workpieces 12 are shorter than the distance A between adjacent tabs 23 of the table 6. Despite the long sides 25 of both workpieces 12 being longer than the distance A, the elongated workpieces 12 would tip over or fall between the tabs 23 in the illustrated orientation with the long sides 25 parallel to the tabs 23. To prevent this, the elongated workpieces 12 are fixed in position in the scrap skeleton part 17d by the nanojoints 14. In this case, one nanojoint 14 is respectively arranged on one of the short sides 24. The second nanojoint 14 is respectively arranged on one of the long sides 25. The distance E between both nanojoints of each workpiece 12 may be at least 2 / 3 of the length of the workpiece.

[0058] The application surface 21 for the gripper of the removal device may be provided on the scrap skeleton part 17d. If the cutting gap along the finish line 19 of the workpiece 12 is narrow enough, it is also possible for the application point 21 to extend to one workpiece 12 and to the adjacent scrap skeleton part 17d.

[0059] FIG. 6 shows a sheet metal 6 with a group 26 of workpieces 12 which are connected to one another via nano-joints 14. The adjacent workpieces 12 in this figure have a number of common finish lines 27. Along one of these common finish lines 27, at least two workpieces 12 are adjacent to one another. The finish lines of each workpiece include at least one common finish line 27. The main area of ​​this common finish line 27 is separated when cutting out the workpieces 12. In the joining area of ​​the common finish line 27, nano-joints 14 remain. Via these nano-joints 14, the workpieces 12 are connected to one another. In this description, a complex of workpieces 12 which are directly connected to one another is also called a nest.

[0060] The group 26 of workpieces 12 generally has an outer circumferential finish line 28. The outer circumferential finish line 28 is formed by a free finish line 29 of a workpiece 12 that is not adjacent to another workpiece 12 of the group 26. The free finish line 29 is part of the finish line of a workpiece 12 located on the outside in the nest.

[0061] Along the outer finishing line 28, the sheet 6 is cut off completely. The group 26 can thus be removed from the scrap portion 30 of the sheet 6. For this purpose, a gripper of the removal device can act directly on one or more workpieces 12. In FIG. 6, for example, three action surfaces 21 for a vacuum gripper are marked, which are located approximately diagonally through the group 26. To separate the workpieces 12 from one another, the group 26 can be inserted into a separating device (not shown), which individualizes the workpieces 12 after they have been released by the removal device.

[0062] A general flow chart of a method for cutting at least one workpiece, and preferably multiple workpieces, from a sheet of metal is shown in Figure 7. In step 102, the sheet of metal is placed on the table of a laser cutting machine.

[0063] Then, in step 104, laser processing is performed. For this, a laser beam is directed at the sheet metal. The impact point of the laser beam is moved along the finish line of at least one workpiece. In the main area of ​​the finish line of each workpiece, the sheet metal is completely cut. In at least one joining area of ​​the finish line of each workpiece, the laser processing is controlled in such a way that a joint is left between the workpiece and the adjacent part of the sheet metal. This joint has a height that is smaller than the thickness of the sheet metal. To form a joint of small height (so-called nano-joints), the laser power can be reduced. The adjacent part can be another workpiece or a scrap skeleton part.

[0064] In a subsequent step 106, the composite of at least one workpiece and adjacent parts is removed from the table. A group of workpieces, possibly comprising scrap skeleton parts, may have been previously separated in step 104 from the scrap parts of the sheet metal.

[0065] Finally, at least one workpiece is separated from the adjacent parts in step 108. In particular, all workpieces of the composite are individualized from each other and from any scrap skeleton parts that may be present. [Explanation of symbols]

[0066] 1 Laser cutting machine 2 Laser beam oscillator 3 Processing head 4 Tables 5 Laser beam 6 thin plate 7 Cutting Gas 8 Suction device 9 Suction passage 10 Cutting gas nozzle 11 Cutting gap 12 Work 13 Adjacent parts 14;14a,14b Joint (nano joint) 15 Control device 16 Group with workpiece 12 and scrap skeleton part 17;17a,17b;17c,17d Scrap skeleton parts 18 Scrap skeleton part outline 19 Finishing Line 20 Inner Contour 21 Action surface 22 Thin plate part 23 Tabs 24 Short Side 25 Long side 26 Group of 12 interconnected works 27 Common Finish Line 28 Outside finish line 29 Free Finish Line 30 Scrap Parts K trajectory curve S Piercing point D thickness of thin plate 6 d Height of joints 14; 14a, 14b L Length of joint 14; 14a, 14b A. Spacing between tabs 23 E Distance 102 Placement 104 Laser processing 106 Take Out 108 Separation

Claims

1. A method for punching at least one workpiece (12) from a thin plate (6), comprising: A) placing the thin plate (6) on the table (4) of a laser cutting machine (1); B) directing a laser beam (5) at the thin plate (6) along the finishing line (19) of the workpiece (12), cutting the thin plate (6) in the main range of the finishing line (19), and leaving at least one connecting portion (14; 14a, 14b) having a height (d) smaller than the thickness (D) of the thin plate (6) in at least one connecting range of the finishing line (19) between the workpiece (12) and the adjacent portion (13) of the thin plate (6); C) removing the at least one workpiece (12) and the adjacent portion (13) connected thereto from the table; D) separating the at least one workpiece (12) from the adjacent portion (13). A method comprising the above steps.

2. The method according to claim 1, characterized in that the height (d) of the connecting portion (14; 14a, 14b) of small height is at most 1 / 3, preferably at most 1 / 4, and particularly preferably at most 1 / 6 of the thickness (D) of the thin plate (6).

3. The method according to claim 1 or 2, characterized in that the length (L) of the connecting portion (14; 14a, 14b) of small height, measured along the finishing line (19), is at most half and / or at least 1 / 4 of the thickness (D) of the thin plate (6).

4. The method according to claim 1 or 2, characterized in that in step B), a group (26) of the plurality of workpieces (12) is formed, which are connected to each other via a connecting portion (14) of small height at at least one common finishing line (27) of the plurality of workpieces (12).

5. The method according to claim 4, characterized in that the group (26) of the plurality of workpieces (12) has an outer finishing line (28) extending over the entire circumference formed by the finishing line (29) of the workpiece (12) along which the thin plate (6) is cut.

6. The method according to claim 4, characterized in that in step C), a taking-out device is made to act on one of the workpieces (12) of the group (26).

7. In step B), a group (16) of a plurality of workpieces (12) is formed that continues to be connected to one common scrap skeleton part (17; 17a, 17b; 17c, 17d) via at least one connecting part (14) of a small height, respectively, and in step C), the plurality of workpieces (12) and the adjacent scrap skeleton part (17; 17a, 17b; 17c, 17d) are taken out together. The method according to claim 1 or 2, characterized in that.

8. Prior to step C), the scrap skeleton part (17; 17a, 17b; 17c, 17d) is separated from the thin plate (6) along a contour (18) extending particularly over the entire circumference. Preferably, the contour (18) is concave. The method according to claim 7, characterized in that.

9. The minimum distance of the contour (18) from the workpieces (12) of the group (16) is at least 12 mm, preferably greater than the thickness (D) of the thin plate (6), and / or at least one working surface (21) with a diameter of at least 120 mm for the taking-out device is left on the scrap skeleton part (17; 17a, 17b; 17c, 17d) that does not have the workpieces (12). The method according to claim 8, characterized in that.

10. The method according to claim 7, characterized in that in step C), a taking-out device is made to act on the scrap skeleton part (17; 17a, 17b; 17c, 17d).

11. The table (4) has tabs (23) extending parallel to each other, and one of the workpieces (12) having a width narrower than the distance (A) between two adjacent tabs (23) has acquired two coupling parts (14) of small height. Preferably, the first coupling part of the coupling parts (14) of small height is arranged on the short side (24) of the workpiece (12). Particularly preferably, the second coupling part of the coupling parts (14) of small height is arranged on the long side (25) of the workpiece (12), particularly at least 60% of the length of the workpiece (12) away from the first coupling part (14). The method according to claim 1 or 2, characterized in that.

12. In order to take out in step C), a taking-out device having a vacuum gripper, a magnetic gripper, a Bernoulli gripper and / or a mechanical gripper, particularly a parallel gripper, is used. The method according to claim 1 or 2, characterized in that.

13. The separation in step D) is performed by oscillation, pressing, blowing or suction, particularly magnetic suction or suction by negative pressure. The method according to claim 1 or 2, characterized in that.

14. The separation in step D) is performed while the taking-out device used for taking out in step C) holds the workpiece (12) indirectly or directly. The method according to claim 1 or 2, characterized in that.

15. The separation in step D) is performed after the taking-out device used for taking out in step C) releases the workpiece (12), particularly after lowering it to the separation device. The method according to claim 1 or 2, characterized in that.

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