Jet cutting of parts from sheet metal plates, taking into account interference contours caused by inclined parts.

Abstract

The present invention relates to a method for cutting sheet metal parts. A sheet metal plate is placed on a plurality of support bars. The sheet metal parts that may tilt during the cutting process are determined. Here, the support bars that are actually present are considered. The machining program for cutting the sheet metal parts is modified to prevent the cutting head from colliding with the tilted sheet metal parts. For this purpose, interference contours by the potentially tilted sheet metal parts are calculated for various positions of the support bars in the region around the target position. Information on the calculated interference contours for various assumed support bar positions is aggregated in a predefined format. The modified machining program prevents the cutting head from entering the region of interference contours of sheet metal parts that have already been cut during the execution of the program.

Description

Technical Field

[0001] The present invention relates to a method for cutting out parts from a sheet metal plate using a beam cutting machine having a cutting head, the beam cutting machine having a workpiece support having a plurality of support bars for the sheet metal plate, and the support bars being capable of being arranged at predetermined grid positions.

[0002] Such methods and beam cutting machines are generally known, for example, from DE102019126403A1 or DE102019104649B4. In many cases, a laser cutting machine having a laser cutting head is used.

[0003] For the laser cutting of (sheet metal) parts, in particular, so-called flat bed machines are used, on which the sheet metal plate lies on a workpiece support having a plurality of spaced support bars. The support bars can have a protruding tip for limiting local contact with the sheet metal plate. The parts are cut out by moving the laser cutting head relative to the workpiece support having the sheet metal plate. Due to the point-like or line-like support via the support bars arranged at a distance from each other, depending on the size of the cut-out parts and their position relative to the support bars, the individual cut-out parts can be inclined. Then there is a risk that the laser cutting head collides with the raised area of the part. This can damage the laser cutting machine and / or the part. Manual intervention may also be required to continue production.

[0004] The patent DE102019104649B4 mentioned at the beginning relates to a method for obtaining the position of at least one support bar in the arrangement of support bars on a pallet. This pallet is intended for use in flatbed machine tools, particularly laser cutting or punching flatbed machine tools. According to this method, the pallet is illuminated with spatially structured light. The position of the support bars relative to the raw material sheet can also be determined, and the shape of the workpiece to be cut can be positioned (nested) on the raw material sheet according to specific parameters relative to the support bars, and then cut from there. Considering the arrangement of the support bars relative to the raw material sheet, for example, irradiation paths extending beyond the support surface of the support bars can be avoided so that the amount of laser beam exposure to the support bars is reduced and the likelihood of damage to the support bars is lowered. Furthermore, tilting motion of large parts can be avoided, for example, by supporting large parts in a targeted manner at a stable point on the support bars. In this regard, DE102019104649B4 does not describe in detail what specific measures are taken.

[0005] As already mentioned at the beginning, DE102019126403A1 describes a method for loading a material sheet into a sheet loading device of a flatbed machine tool, in which the material sheet is fed for machining on the flatbed machine tool starting from a target position assigned to machining in the machine coordinate system, and the flatbed machine tool is equipped with a camera system having at least one camera. This camera system is designed to record an image of the sheet loading device that is spatially calibrated with respect to the machine coordinate system of the flatbed machine tool. This method, - A step of recording an image of the material sheet in the area of ​​the sheet mounting device, - A step of evaluating the image acquisition and determining the actual seat position in the machine coordinate system, - The process includes the steps of obtaining the determined actual sheet position deviation from the target position, and using the obtained deviation to align and position the material sheet.

[0006] The control system of a flatbed machine tool, particularly a laser control system, can detect the actual (current) position (e.g., whether it is within the tolerance range) and, through conversion, adapt the corresponding machining program (e.g., cutting plan) to the actual position. The target position can be manually predetermined according to DE102019126403A1 or calculated based on the support bar configuration on the laser flatbed machine at the time of loading. Furthermore, the target position can be determined based on the nesting of parts on the material sheet, in particular, depending on parameters such as avoiding part tilting, optimal support of parts during the cutting process, avoiding slag scattering, and avoiding welding to the sublayer of parts. Moreover, the nesting of the parts to be created can be adapted later, particularly optimized, based on the loading position and the support bar configuration. This can also be done based on parameters such as avoiding part tilting, optimal support of parts during the cutting process, avoiding slag scattering, and avoiding welding to the sublayer of parts. DE102019126403A1 still does not describe specific measures regarding this point. [Background technology]

[0007] The objective of the present invention is to improve process reliability during beam cutting of sheet metal parts, and in particular to effectively avoid collisions of the cutting head.

[0008] Summary of the Invention According to the present invention, this objective is achieved by the method described in claim 1 and a beam cutting machine having the features defined in claim 18. Each dependent claim and specification provides for advantageous variations or embodiments.

[0009] The present invention provides a method for cutting parts from a sheet of metal using a beam cutting machine having a cutting head. In particular, the beam cutting machine is a laser cutting machine having a laser cutting head. The beam cutting machine has a workpiece support having a plurality of support bars for the sheet of metal, and the support bars can be positioned at predetermined grid positions. To cut out parts, the cutting head can be moved relative to the workpiece support. Generally speaking, the support bars are positioned at most grid positions, typically at least 90% of the grid positions, but do not need to be positioned at all grid positions of the workpiece support. Each support bar may have a plurality of ends for locally supporting the sheet of metal. Typically, the support bars extend in a straight line, and the grid positions are aligned parallel to each other.

[0010] The method is, A) i) Nesting plan for parts cut from a sheet of metal, ii) A machining program for controlling the cutting head during cutting of parts arranged according to a nesting plan from a sheet of metal, iii) A predetermined tolerance range for the position of the support bar, Step A) specifies, B) i) Grid position where a support bar exists, ii) Position of the sheet metal plate placed on the workpiece support, Step B) to obtain, C) Step C) determines where the support bar is positioned relative to the sheet metal plate, particularly relative to the individual parts being cut out, D) A step of calculating a set of interference contours that may occur when a component of a given nesting plan is tilted on a support bar, wherein the set of interference contours is calculated each time for multiple positions on the support bar within their respective tolerances, E) Step E) to determine the set of effective interference contours from the calculated set of interference contours, F) A step of modifying a machining program, wherein the distance between the cutting head and the interference contour of an already separated part does not fall below a predetermined minimum distance for a valid set of interference contours during the execution of the modified machining program. G) includes the step of cutting out a part according to a modified machining program.

[0011] A nesting plan describes the positions of parts to be cut out on a sheet of metal. When a machining program is executed, the parts are cut out according to the nesting plan. For this purpose, the machining program defines the relative motion of the cutting head and the workpiece support. The nesting plan for the parts can be implicitly predetermined by the machining program.

[0012] In practice, support bars are often not precisely positioned at the grid locations. The actual position of the support bars may deviate from the grid locations due to deformation, for example. For example, the support bars may bend or wear down. The holders for the support bars may also deform or develop some play. Therefore, regardless of the underlying mechanism, one or more support bars may not extend to the intended (target) position but into the surrounding area. The maximum expected deviation from the target position is described by the width of the tolerance. Thus, it is assumed that the support bars are within the tolerance at each grid position. In other words, it is assumed that the support bars are within a tolerance of a given width for each grid position. Typically, the tolerance is the same size for all grid positions.

[0013] In particular, with replaceable support bars, a support bar is not necessarily present at every grid position. Therefore, the grid positions where support bars exist are obtained. Because there is a predetermined tolerance, it is not necessary to precisely determine the position of each support bar; it is sufficient to know which grid positions have support bars.

[0014] The position of the sheet metal plate on the workpiece support may also fluctuate. Therefore, the position of the sheet metal plate relative to the workpiece support is also obtained.

[0015] The grid position of the support bar and / or the position of the sheet metal plate can be acquired by a camera. The camera can be positioned on the housing of the beam cutting machine. The grid position of the support bar and / or the position of the sheet metal plate can be acquired by a sensor device. The sensor device can be positioned on the housing of the beam cutting machine. For this purpose, the sensor device can be a radar, lidar, ultrasonic, laser beam sheet, induction, or capacitance measurement method. The sensor device and / or camera can be guided in a movable manner by a holding device.

[0016] Using predetermined data regarding the presence of support bars and the position of the sheet metal plate on the workpiece support, the points at which the sheet metal plate is supported by the support bars are determined. In particular, it is determined where components placed within a nesting plan are supported by the support bars.

[0017] Depending on the size and position of a part, it may tilt around one of the support bars after being cut off (completely cut out). This can result in an interference contour. The interference contour specifically represents the area above the workpiece support from which the tilted or tilted part can protrude. In particular, the part may remain in a tilted position and protrude above the support surface of the workpiece support. The interference contour can be calculated as the solid of revolution of the tilted part. If the center of gravity of the part is located beyond the external support bar of the part in question, it can be assumed that the part will tilt; otherwise, it can be assumed that the part will not tilt and no interference contour will be created. Parts supported by only a single support bar will typically tilt.

[0018] Since the position of the support bars can vary as described above, the interference contours of potentially tilting parts are calculated for multiple different positions of the support bars within their respective tolerances. The position of the support bars can vary, for example, in predetermined increments within the tolerance. In particular, at least five positions can be mathematically checked for each support bar. In this regard, it is advantageous to include tolerance limits. Preferably, all combinations of support bar positions within each tolerance are sequentially checked for potential interference contours (as many as the number of positions selected for each tolerance). In this way, a set of interference contours is determined for each combination of support bar positions under consideration.

[0019] From a set of numerous interference contours, a set of effective interference contours is determined by aggregating information from each set in a predetermined format. This set of effective interference contours is also referred to as the effective set of interference contours.

[0020] The set of effective interference contours can be determined from a calculated set according to predetermined criteria. In particular, the calculated interference contours of multiple sets can be superimposed onto the effective set. For each potentially inclined part, the interference contour with the largest volume and / or maximum height can be included in the effective set of interference contours, depending on the position of the support bar.

[0021] Based on the set of effective interference contours, the machining program is modified so that the cutting head does not cross areas of potential interference contours. To this end, the machining program is adapted so that the minimum distance between the cutting head and the interference contours of parts already separated in the modified machining process is always maintained. It should be noted that before the part is completely cut (separated), only the separated part can be tilted and therefore can traverse areas of potential interference contours.

[0022] Finally, the modified machining program is executed to cut out the part. By changing the machining program as described above, interruptions, particularly collisions, during the part cutting process are reduced.

[0023] Overall, the method according to the invention improves productivity by providing a cutting process without interruptions and collisions in the beam cutting machine and without unexpected downtime. In particular, by avoiding nozzle collisions and reducing wear of the support bars, less wear of the machine can also be achieved. In addition, resulting damage to the cutting head, moving unit, bellows, etc. is avoided. The lower frequency of collisions reduces the need for manual intervention on the machine, thus also reducing the risk of injury during the cutting operation. Furthermore, it is no longer necessary for an operator to be constantly present next to the beam cutting machine. Downstream processes such as automatic extraction also benefit from the targeted prevention of tilting. In addition, in the upstream processes for order planning and CAD / CAM programming, the effort for fine-tuning the machining program can also be reduced. Finally, by improving cutting stability, the reliability of the cutting process is improved. Overall, unplanned downtime is reduced, resulting in greater economic efficiency.

[0024] Steps A) and B), and sub-steps i) to iii) or i) and ii) of step A) or B) can each be carried out in any order and / or at least partially simultaneously.

[0025] During the execution of steps C) to F), a setup process or maintenance measures can be carried out on the beam cutting machine.

[0026] The method according to the invention is preferably carried out using the beam cutting machine according to the invention described below.

[0027] The workpiece support is movable between the loading position and the machining position. This makes it easier to place the sheet metal plate on the workpiece support.

[0028] Preferably, the grid position of the (current) support bar and / or the position of the sheet metal plate are obtained when the workpiece support is in the loading position. The workpiece support is usually easily confirmed, for example, using a camera. In addition, steps of other methods can be performed using the time required to move the workpiece support to the machining position.

[0029] Preferably, steps D), E), and F) are performed at least partially while the workpiece support is being moved from the loading position to the machining position. This reduces the time between the placement of the sheet metal plate and the beam cutting machine beginning to cut the part.

[0030] In particular, after reaching the machining position, the start of step G) can be delayed until steps D) through F) are completed. The conventional approach to maximizing machine utilization is to avoid downtime as much as possible. However, the method according to the present invention can reduce operational interruptions during cutting to a certain extent, resulting in an overall reduction in production time or higher productivity due to a certain delay at the start of machining.

[0031] Preferably, in step D), the set of interference contours is further calculated for different positions of the sheet metal plate within a given region relative to the acquired position of the sheet metal plate. In this way, potential interference contours are determined for various positions of the sheet metal plate within a given region around the acquired position and for various positions of the support bar. This way, inaccuracies in acquiring the position of the sheet metal plate can be compensated for.

[0032] The set of effective interference contours can correspond to the calculated set of interference contours having the maximum volume of interference contours and / or the maximum height of interference contours above the sheet metal plate. Therefore, the worst-case scenario is assumed when adapting the machining program.

[0033] Alternatively, the set of effective interference contours can correspond to the envelope contours of multiple calculated sets, particularly all calculated sets of interference contours. In this way, multiple, preferably all, possible interference contours are used to adapt to the machining program. The envelope contour can be the convex envelope of the calculated interference contours.

[0034] In step F), several modified variants of the machining program can be determined, and one of the variants can be selected according to predetermined criteria. This makes it possible to obtain a machining program optimized in a particularly effective manner. At the same time, less favorable variants are filtered out and favorable variants are selected instead, so only a few specifications or preliminary information are needed to determine the variant of the machining program. These criteria may include, for example, maximizing the integral of the distance between the cutting head and the interference contour of the already separated part. These criteria may relate to the point in time during the execution of the machining program when the part representing the potential interference contour is separated. In particular, a variant of the machining program can be selected in which the potential interference contour is created as late as possible in the execution of the machining program.

[0035] In step F), the order in which the part and / or partial contours of the part are cut out can be changed. In this manner, collisions with parts that may tilt can be avoided particularly easily and effectively. In particular, for example, large parts cannot be cut out in one piece but can be cut out sequentially along multiple partial contours. Small parts that fall between the support bars after being cut out can be cut out within a predetermined time range, preferably at the start of the machining program, and removed via a conveyor system below the workpiece support. The conveyor system can be a (scrap) conveyor belt that is synchronized in chronological order with the accumulation of small parts or scrap pieces.

[0036] In step F), the path of the movement can be altered to perform positioning movements without cutting, in particular, so as to bypass already separated parts. Alternatively or additionally, the distance between the cutting head and the sheet metal can be increased, and / or the cutting gas pressure above already separated parts can be reduced. These measures can also effectively reduce the risk of collision in a simple manner, usually at the cost of slightly longer machining time. In principle, the aim is to shorten the length of the movement path over separated parts, i.e., to avoid such parts as much as possible. If they cannot be avoided by altering the course, the other measures described above can be taken.

[0037] In step F), additional cutting of the scrap piece may be specified. Thus, the scrap piece is chopped in step G). Each individual piece of the scrap piece falls between the support bars and can be disposed of via a conveyor system below the workpiece support, such as a (scrap) conveyor belt.

[0038] In step F), - The position of the connection points of the parts specified in a predetermined machining program can be changed relative to the scrap skeleton of the sheet metal plate, and / or - The connection points of parts specified in a predetermined machining program can be removed from the scrap skeleton of a sheet metal plate, and / or - Additional connecting parts can be inserted into the scrap skeleton of the sheet metal plate.

[0039] These connections or joints are also referred to as "micro-joints" or "nano-joints" and are later separated (typically outside the machining area), for example, manually or by an extraction system. The aforementioned modifications make it possible to provide the number of connections necessary to avoid tilting of the part, and any connections beyond this limit are avoided.

[0040] In step F), the nesting plan of the parts on the sheet metal plate can be changed. For this purpose, individual parts can be shifted and / or rotated on the sheet metal plate, typically within predetermined limits. In particular, parts can be positioned so as not to tilt on the support bar. In this way, collisions between the cutting head and tilted parts can be effectively and easily avoided.

[0041] In particular, the nesting plan can be modified to shorten the length of the cutting path above the support bar. This reduces wear on the support bar by the cutting beam.

[0042] In step F), the machining program can be modified to reduce, and preferably avoid, the drilling process in the support bar area. To this end, the location of the drilling point for one of the parts can be changed. Alternatively or additionally, this can be achieved by changing the nesting plan (i.e., changing the position and / or alignment of at least one of the parts on the sheet metal plate). If drilling beyond the support bar, there is a risk that the drilling process will not proceed as expected. In addition, the drilling process also reduces wear on the support bar. The support bar area typically consists of a tolerance at its grid position. An additional safety distance to the edge of the tolerance can be predetermined.

[0043] If the cutting head collides with the sheet metal, one of the parts, or a piece of scrap during step G), steps B)ii) to F) can be repeated, and then the machining program can be modified again to continue step G) for the remainder of the cutting operation. In the event of a collision, the sheet metal may shift on the workpiece support. This is compensated for by repeating the aforementioned steps. To repeat step B)ii), the workpiece support can be moved to the loading position.

[0044] Furthermore, within the scope of the present invention are beam cutting machines having a cutting head, and in particular laser cutting machines having a laser cutting head, which are, - A workpiece support having multiple support bars for a sheet metal plate, wherein the support bars can be positioned at predetermined grid positions, - A device, particularly a camera, for obtaining the grid position where the support bar is located, and for obtaining the position of the sheet metal plate placed on the workpiece support. -Having a control device for controlling the cutting head, The control device can store nesting plans for parts on a sheet of metal, machining programs for cutting parts from the sheet of metal, and tolerance widths for the position of support bars. The control device is designed (programmed) to perform steps B) to G) of the method according to any one of the prior claims.

[0045] The beam cutting machine enables the implementation of the method according to the present invention, according to a nesting plan, a machining program, and a tolerance width. The nesting plan can be implicitly defined by the machining program.

[0046] The beam cutting machine may have further features described in relation to the method according to the present invention.

[0047] To perform step B), the control device may use an acquisition device (camera). To perform step G), the control device controls the cutting head according to the modified machining program. The workpiece support is movable between the loading position and the machining position.

[0048] The control device can be a local control device for a single beam cutting machine. Alternatively, the control device can be a central control device for multiple beam cutting machines. It is also conceivable that the control device be distributed between the local control component and the central control component.

[0049] Further features and advantages of the present invention can be found in the specification, claims, and drawings. According to the present invention, the above-described features and further described features may be used individually or together in any desired combination in each case. The illustrated and described embodiments should not be understood as an exhaustive list, but rather as exemplary features for illustrating the present invention.

[0050] The present invention is illustrated by the drawings and by exemplary embodiments. [Brief explanation of the drawing]

[0051] [Figure 1] A schematic perspective view shows a beam cutting machine according to the present invention, which has a workpiece support section on which a sheet metal plate is arranged, and the workpiece support section is in the input position and is acquired by a camera. [Figure 2] A schematic cross-sectional view shows the details of the beam cutting machine shown in Figure 1, which has a workpiece support section and a movable cutting head located at the machining position, with a support bar missing at the grid position of the workpiece support section. [Figure 3] Figure 2 shows a schematic cross-sectional view of the workpiece support section of the beam cutting machine, demonstrating that the position of the support bars can be varied within specific limits at each grid position. [Figure 4] A schematic top view shows a sheet metal plate with a nesting plan for the cut-out parts. [Figure 5] A schematic side view shows the components that are stably mounted on three support bars. [Figure 6] Figure 5 shows a schematic side view of the component, illustrating the interference contour resulting from the tilt of the component due to the relative misalignment between the support bars and the relative misalignment of the component with respect to the support bars. [Figure 7] This diagram shows a schematic flow chart of the method for cutting parts from a sheet metal plate according to the present invention. [Figure 8]The convex envelope of the interference contour of the component, which tilts in different ways depending on the position of the support bar, is shown in a schematic side view.

[0052] Figure 1 shows a beam cutting machine in the form of a laser cutting machine 10. The workpiece support 12 is located at the outside loading position of the housing 14. A sheet metal plate 16 is placed on the workpiece support 12, and in Figure 1, a nesting plan of the cut parts 18 is drawn on the sheet metal plate 16. In practice, the nesting plan is typically not drawn on the sheet metal plate 16 but is stored in the control device 20. A camera 22 captures the workpiece support 12 and the sheet metal plate 16. Here, the camera 22 is mounted on the housing 14.

[0053] In Figure 2, the workpiece support 12 is located in a machining position inside the housing 14 (not shown in Figure 2; see Figure 1). The laser cutting head 24 is movable along three axes 26, 28, and 30 above the workpiece support 12. The laser cutting head 24 has a nozzle 32 from which a laser beam and cutting gas jet are ejected to cut out the part 18.

[0054] Figure 2 shows that the workpiece support 12 has a plurality of support bars 34 extending substantially parallel to each other, where each support bar 34 extends perpendicular to the drawing plane. The support bars 34 may have ends (details not shown) for establishing point contact with the sheet metal plate 16. The support bars 34 are interchangeably arranged at a certain distance from each other at predetermined grid positions 36. It is possible that one or more of the grid positions 36 do not have a support bar 34. For example, in Figure 2, the support bar at the fourth grid position from the left is missing. The grid positions 36 can be defined by the holders of the support bars 34.

[0055] A conveyor belt 38 can be positioned below the support bars 34. The conveyor belt 38 can be used to discharge small parts or scraps that fall between the support bars 34.

[0056] Figure 3 illustrates that the actual position of each support bar 34 at its grid position 36 can vary within certain limits, for example, due to deformation, damage, or play in the holder. The possible positions of the support bars 34 can be described by a tolerance 40 having a determined width 42, depending on the type of workpiece support 12 and support bar 34. In Figure 3, the outermost position of the support bar 34 within each tolerance 40 is shown by a dashed line in each case.

[0057] A method for cutting out part 18 from a sheet metal plate 16 will be described with further reference to the flowchart shown in Figure 7 and the nesting plan in Figure 4, which has four exemplary parts 18.1 to 18.4.

[0058] First, a nesting plan is predetermined (step 102), and the arrangement of parts 18.1 to 18.4 according to the original nesting plan is shown by solid lines in Figure 4. In addition, a machining program is specified to control the laser cutting machine 10 to cut out parts 18.1 to 18.4 according to the predetermined nesting plan (step 104). The nesting plan can be implicitly defined by the machining program or set individually. The nesting plan can be defined for the sheet metal plate 16, or alternatively for the workpiece support 12. The machining program and nesting plan are stored in the control device 20. In addition, the width 42 of the tolerance range 40 is predetermined (step 106) and stored in the control device 20.

[0059] While the workpiece support 12 is in the loading position (see Figure 1), the sheet metal plate 16 is placed on the workpiece support 12 (step 108). For this purpose, the workpiece support 12 may have been moved to the loading position in step 107. Typically, before placing the sheet metal plate 12, or in special cases after, the camera 22 is used to obtain the actual grid position 36 of the support bar 34 (step 110). In addition, the camera 22 obtains the position of the sheet metal plate 16 on the workpiece support 12 (step 112). Instead of, or in addition to, the camera 22 may be provided to obtain the positions of the support bar 34 and the sheet metal plate 16 (details not shown), for example, tactile sensors and / or photoelectronic sensors, such as a light barrier. From this information, in step 114, it is determined where the sheet metal plate 16 is located relative to the workpiece support 12, and in particular relative to the grid position 36. In the illustrated exemplary embodiment, steps 110 and 112 are also performed while the workpiece support 12 is in the loading position.

[0060] The initially predetermined machining program may specify that the part be cut in the order of 18.1, 18.2, 18.3, and 18.4 (see Figure 4).

[0061] When the support bar 36 and the sheet metal plate 16 are in their target positions, part 18.1 can be supported by the three support bars 34.1 to 34.3, as shown in Figure 5. On the other hand, if the sheet metal plate 16 with part 18.1 is oriented slightly offset (to the left in this case) on the workpiece support 12, with support bar 34.2 offset toward support bar 34.1 and support bar 34.3 offset away from support bars 34.1 and 34.2, the situation shown in Figure 6 may occur, in which case part 18.1 is supported only by two support bars 34.1 and 34.2 and not by support bar 34.3. Furthermore, since the center of gravity of part 18.1 is between support bars 18.2 and 18.3, part 18.1 will tilt after being detached. This creates an interference contour 44 with a height of 46.

[0062] Interference contours may similarly occur for other parts 18.2-18.4 and / or other misalignments of the support bars 34. Therefore, in step 116, for different positions of each support bar 34 within its tolerance 40, and preferably different positions of the sheet metal plate 16 relative to the workpiece support 12, it is calculated which parts 18 in each configuration may tilt after being detached. In particular, the shape of the interference contours 44 that may be created when tilted and their possible heights 46 can be calculated. In this way, a set of interference contours 44 is obtained for each combination of different support bar positions within their respective tolerances 40 and different positions of the sheet metal plate 16.

[0063] Information regarding interference contours 44 from various sets is compiled in step 118 into a set of valid interference contours (hereinafter also referred to as the valid set).

[0064] For each part 18 or 18.1-18.4, the maximum height 46 of the resulting interference contour 44 can be stored in the set of valid interference contours. Alternatively or additionally, for each part 18 or 18.1-18.4 in the valid set, the maximum volume of the resulting interference contour 44 can be stored.

[0065] In a valid set of interference contours, the envelope contours 47 of the possible interference contours 44, 44' that may occur for each part can be stored as valid interference contours for each part 18 or 18.1 to 18.4 (see Figure 8). Figure 8 shows that for the same part 18, depending on the assumed position of the support bar 34 (shown by dashed or dotted lines), this part 18 can be tilted in different ways. Each interference contour 44 or 44' above the workpiece support 12 can be surrounded by an envelope contour 47 in the smallest convex space, in other words, the envelope contour 47 can be the convex envelope of the interference contour 44.

[0066] For components that are not expected to tilt in any of the considered configurations, the corresponding information can be stored in the active set.

[0067] In step 120, the machining program is modified based on a valid set of interference contours such that the laser cutting head 24 always maintains a predetermined minimum distance, typically several millimeters or several centimeters, from the interference contours of parts 18, 18.2-18.4 that have already been separated in the machining process and are stored in a valid set. To determine a suitably modified machining program, several variants of the modified machining program can be determined, and the optimal variant can be selected from among them according to predetermined criteria.

[0068] In the illustrated example (see Figure 4), the movement path 48 (dotted line) of the laser cutting head 24 between the cutting of parts 18.2 and 18.3 may extend beyond the already separated part 18.1 (solid line) to the drilling point 50 in the originally predetermined machining program, particularly in the region of its interference contour 44 (see Figure 6). Therefore, there is a risk that the laser cutting head 24 will collide with the inclined part 18.1. The machining program is modified to avoid this collision. Various procedures can be considered for this purpose and can be used individually or in combination depending on the situation.

[0069] One possible modification to the machining program is to change the course of the travel path 48 so that it extends beyond the part 18.1 and its interference contour 44. The modified travel path 48' is shown as a dotted line in Figure 4. Alternatively or additionally, during the positioning motion along the travel path 48 or 48', the height of the laser cutting head 24 above the sheet metal plate 16 can be increased, and / or the pressure of the cutting gas discharged from the nozzle 32 can be reduced.

[0070] To prevent part 18.1 from tilting, its position and / or alignment on the sheet metal plate 16 can be altered. In other words, the nesting plan can be changed. Figure 4 shows the arrangement of part 18.1 rotated and shifted in the direction of axes 26, 28, as indicated by the dashed lines, which increases the overlap with support bars 34.1 and 34.3 (see Figures 5 and 6). By altering the nesting plan, it is also possible to ensure that the cutting line does not extend along one of the support bars 34.

[0071] In addition, or alternatively, during the cutting process, a connection 52 (a so-called micro-joint) between part 18.1 and the scrap skeleton 54 can be inserted. This connection 52 initially holds part 18.1 to the scrap skeleton 54 and is separated after all parts 18.1 to 18.4 have been cut out. In a corresponding manner, the position of the connection to the scrap skeleton 54 can be changed as needed, and if necessary, any unnecessary connections to the scrap skeleton 54 can be removed.

[0072] It is also possible to change the order in which parts 18.1 to 18.4 are cut. In this regard, it is possible to cut the parts in the order of 18.2, 18.1, 18.3, and 18.4. In this way, the length of the positioning motion without cutting (see movement paths 48 and 48') can also be shortened under certain circumstances.

[0073] In step 116, a set of interference contours of potentially inclined scrap pieces, such as scrap pieces 56 inside part 18.3, can also be calculated and included in the effective set in step 118. To avoid collisions with inclined scrap pieces 56, the machining program can be modified in step 120 to cut these scrap pieces 56 into smaller pieces that fall safely between the support bars 34. These are then discharged via the conveyor belt 38 (see Figure 2).

[0074] In step 120, the position of the drilling point 50 can also be changed to avoid the drilling process being performed on the support bar 34. This does not directly contribute to collision avoidance in the current cutting process, but it does reduce wear on the support bar 34. Thus, the position of the support bar 34 varies only within a narrower tolerance range, so the tolerance range 40 remains smaller, and as a result, fewer interference contours are determined.

[0075] Steps 114, 116, 118, and 120 can be performed at least partially while the workpiece support 12 is being moved from the loading position (see Figure 1) to the machining position (see Figure 2) in step 121. Preferably, steps 114, 116, 118, and 120 are performed by a control device 20, which is programmed accordingly.

[0076] Next, in step 122, parts 18.1 to 18.4 are cut out according to the modified machining program. If steps 114 to 120 are not yet completed when the parts reach the machining position, the start of the cutting process is delayed until step 120 is completed.

[0077] If, contrary to expectations, a collision occurs during the cutting process, steps 112-120 can be repeated (see dashed arrows in Figure 7). The workpiece support 12 can be moved to the loading position to perform step 112 again (repeat step 107). Before cutting out the remaining parts using the modified machining program in the next step 122, the workpiece support 12 is returned to the machining position (repeat step 121).

[0078] In summary, the present invention relates to a method for cutting sheet metal parts. A sheet metal plate is placed on a plurality of support bars. The sheet metal parts that may tilt during the cutting process are determined. Here, the support bars that are actually present are considered. The machining program for cutting the sheet metal parts is modified to prevent the cutting head from colliding with the tilted sheet metal parts. For this purpose, interference contours by the potentially tilted sheet metal parts are calculated for various positions of the support bars in the region around the target position. Information on the calculated interference contours for various assumed support bar positions is aggregated in a predefined format. The modified machining program prevents the cutting head from entering the region of the aggregated interference contour of sheet metal parts that have already been cut during the execution of the program. [Explanation of symbols]

[0079] 10 Laser cutting machine 12 Workpiece support section 14 Housing 16 sheet metal plate 18;18.1~18.4 Parts 20 Control Devices 22 cameras 24 laser cutting heads 26, 28, 30 axes 32 nozzles 34;34.1~34.3 Support bar 36 Grid Positions 38 Conveyor belt 40 Tolerance 42 width 44, 44' Interference contour 46 Height of interference contour 44 47 Enveloping contour 48, 48' Travel route 50 drilling points 52 Connection part 54 Scrap Skeleton 56 scrap pieces 102 Specify a nesting plan 104 Specify the machining program. 106 Specify a tolerance of 40 and a width of 42. 107 Move the workpiece support section 12 to the insertion position. Place the 108 sheet metal plate 16. 110 Obtain the grid position 36 of the support bar 34. 112 Obtain the position of the sheet metal plate 16 on the workpiece support 12. 114 Determine the position of the support bar 34 relative to the sheet metal plate 16. 116 Calculate the set of interference contours 118 Determine the set of effective interference contours. 120 Modify the machining program 121 Move the workpiece support 12 to the machining position. Cut out part 18 from 122.

Claims

1. A method for cutting out parts (18; 18.1 to 18.4) from a sheet metal plate (16) using a beam cutting machine having a cutting head, particularly a laser cutting machine (10) having a laser cutting head (24), wherein the beam cutting machine has a workpiece support section (12) having a plurality of support bars (34; 34.1 to 34.3) for the sheet metal plate (16), and the support bars (34; 34.1 to 34.3) can be positioned at predetermined grid positions (36), The method described above is A) i) Nesting plan of parts (18; 18.1 to 18.4) cut out on the sheet metal plate (16), ii) A machining program for controlling the cutting head during the cutting of parts (18; 18.1 to 18.4) arranged from the sheet metal plate (16) according to the nesting plan, iii) A permissible range (40) of a predetermined width (42) relative to the position of the support bar (34; 34.1 to 34.3), The step of specifying, B) i) The grid position (36) where the support bar (34; 34.1 to 34.3) is located, ii) Position of the sheet metal plate (16) placed on the workpiece support portion (12), Steps to obtain, C) A step of determining where the support bars (34; 34.1 to 34.3) are positioned relative to the sheet metal plate (16), and in particular, relative to the individual cut-out parts (18; 18.1 to 18.4), D) A step of calculating a set of interference contours (44, 44') that may result from the tilting of a component (18; 18.1 to 18.4) of a predetermined nesting plan on the support bar (34; 34.1 to 34.3), wherein the set of interference contours (44, 44') is calculated in each case for multiple positions within the respective tolerance range (40) of the support bar (34; 34.1 to 34.3), E) A step of determining a set of effective interference contours from the calculated set of interference contours (44, 44'), F) A step of modifying the machining program such that, as a result, the distance between the cutting head and the interference contour of the already separated parts (18; 18.1 to 18.4) during the execution of the modified machining program does not fall below a predetermined minimum distance for the set of effective interference contours. G) A method comprising the step of cutting out the parts (18; 18.1 to 18.4) according to the modified machining program.

2. The method according to claim 1, wherein the grid position (36) of the support bars (34; 34.1 to 34.3) and / or the position of the sheet metal plate (16) are acquired by a camera (22).

3. The method according to claim 1 or 2, wherein the workpiece support portion (12) is movable between the input position and the machining position.

4. The method according to claim 3, wherein the grid position (36) of the support bar (34; 34.1 to 34.3) and / or the position of the sheet metal plate (16) are obtained when the workpiece support (12) is in the loading position.

5. The method according to claim 3 or 4, wherein steps D), E), and F) are performed at least partially while the workpiece support (12) is being moved from the loading position to the machining position.

6. The method according to claim 5, wherein the start of step G) is delayed until steps D) to F) are completed after reaching the machining position.

7. The method according to any one of claims 1 to 6, wherein in step D), the set of interference contours (44, 44') is further calculated for different positions of the sheet metal plate (16) within a predetermined region relative to the acquired position of the sheet metal plate (16).

8. The method according to any one of claims 1 to 7, wherein the set of effective interference contours corresponds to a calculated set of interference contours having the maximum volume and / or maximum height of the interference contours above the sheet metal plate (16).

9. The method according to any one of claims 1 to 7, wherein the set of effective interference contours corresponds to the envelope contour (47) of the interference contour (44, 44') of a plurality of calculated sets of interference contours (44, 44'), in particular all calculated sets.

10. The method according to any one of claims 1 to 9, wherein in step F), a plurality of modified variants of the machining program are determined, and one of the variants is selected according to a predetermined criterion.

11. The method according to any one of claims 1 to 10, wherein in step F), the order in which the parts (18; 18.1 to 18.4) and / or the partial contours of the parts (18; 18.1 to 18.4) are cut out is changed.

12. In step F), in particular, the course of the movement path (48, 48') is modified for positioning motion without a cutting operation so that parts that have already been detached (18; 18.1 to 18.4) are bypassed, and / or Above the already detached parts (18; 18.1-18.4), - Increase the distance between the cutting head and the sheet metal plate (16), and / or - The method according to any one of claims 1 to 11, for reducing the pressure of the cutting gas.

13. The method according to any one of claims 1 to 12, wherein step F) specifies additional cutting of the scrap piece (56).

14. In step F), - The position of the connection portion (52) of the part (18; 18.1 to 18.4) specified in a predetermined machining program relative to the scrap skeleton (54) of the sheet metal plate (16) is changed, and / or - The connection portion (52) of the part (18; 18.1 to 18.4) specified in the predetermined machining program to the scrap skeleton (54) of the sheet metal plate (16) is removed, and / or - The method according to any one of claims 1 to 13, wherein an additional connecting portion (52) of the part (18; 18.1 to 18.4) is inserted into the scrap skeleton (54) of the sheet metal plate (16).

15. The method according to any one of claims 1 to 14, wherein in step F), the nesting plan of the components (18; 18.1 to 18.4) on the sheet metal plate (16) is modified, in particular to shorten the length of the cutting path above the support bars (34; 34.1 to 34.3).

16. The method according to any one of claims 1 to 15, wherein in step F), the machining program is modified so that the drilling process in the region of the support bar (34; 34.1 to 34.3) is reduced, preferably avoided.

17. The method according to any one of claims 1 to 16, wherein during the execution of step G), the cutting head collides with one of the sheet metal plate (16), the parts (18; 18.1 to 18.4), or a piece of scrap (56), steps B) ii) to F) are performed again, and then the machining program is modified again to continue step G) for the remainder of the cutting operation.

18. A beam cutting machine having a cutting head, in particular a laser cutting machine (10) having a laser cutting head (24), - A workpiece support (12) having a plurality of support bars (34; 34.1 to 34.3) for a sheet metal plate (16), wherein the support bars (34; 34.1 to 34.3) can be positioned at predetermined grid positions (36), - A device, particularly a camera (22), for obtaining the grid position (36) where the support bars (34; 34.1 to 34.3) are located, and for obtaining the position of the sheet metal plate (16) placed on the workpiece support portion (12), - A control device (20) for controlling the cutting head, The control device (20) can store a nesting plan for parts (18; 18.1 to 18.4) on a sheet metal plate (16), a machining program for cutting the parts (18; 18.1 to 18.4) from the sheet metal plate (16), and the width (42) of the tolerance range (40) for the position of the support bars (34; 34.1 to 34.3). A beam cutting machine wherein the control device (20) is designed to carry out steps B) to G) of the method according to any one of claims 1 to 17.

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