Jet cutting of components from a sheet-metal plate taking into account interference contours due to tilting components

Abstract

The invention relates to a method for cutting out sheet-metal parts. A sheet-metal plate rests on a plurality of support bars. Sheet-metal parts which could tilt during the cutting-out process are determined. Account is taken here of which support bars are actually present. A machining programme for cutting out the sheet-metal parts is changed in order to prevent a cutting head from colliding with tilted sheet-metal parts. For this purpose, interference contours due to the potentially tilting sheet-metal parts are calculated for various positions of the support bars in an area around their target position. Information relating to the calculated interference contours for the various assumed support bar positions is aggregated in a predefined manner. The changed machining programme prevents the cutting head from entering the regions of the interference contours of sheet-metal parts that have already been cut free during execution of the programme.

Description

[0001] Beam cutting of components from a sheet metal panel taking into account interfering contours caused by tilting components

[0002] Background of the invention

[0003] The invention relates to a method for cutting out components from a sheet metal panel using a jet cutting machine with a cutting head, wherein the jet cutting machine has a workpiece support with a plurality of support webs for the sheet metal panel, wherein the support webs can be arranged at previously known grid positions.

[0004] Such processes and beam cutting machines are generally known, for example, from DE 102019 126 403 A1 or DE 10 2019 104 649 B4. Laser cutting machines with a laser cutting head are often used.

[0005] For laser cutting of (sheet metal) components, so-called flatbed machines are used in particular. In these machines, a sheet metal panel rests on a workpiece support with several spaced-apart support bars. The support bars can have protruding points for locally limited contact with the sheet metal panel. The components are cut out by moving a laser cutting head relative to the workpiece support with the sheet metal panel. Due to the point- or line-like support via the spaced-apart support bars, depending on the size of the cut-out components and their position relative to the support bars, it can happen that some of the cut-out components tip over. This creates the risk of the laser cutting head colliding with the raised area of ​​the component.

[0006] This can lead to damage to the laser cutting machine and / or the components. Manual intervention may also be required to continue production.

[0007] The aforementioned DE 10 2019 104 649 B4 relates to a method for detecting the position of at least one support web in an arrangement of support webs of a pallet. The pallet is intended for use with a flatbed machine tool, in particular a laser cutting or punching flatbed machine tool. According to the method, the pallet is illuminated with spatially structured light. The positions of the support webs relative to a raw material sheet can also be determined, and the shapes of the workpieces to be cut out can be arranged (nested) on the raw material sheet according to certain parameters with reference to the support webs and cut out from it. Taking into account the arrangement of support webs relative to the raw material sheet makes it possible, for example, to avoid irradiation paths running over support surfaces of the support webs, so that the support webs are less exposed to and damaged by laser radiation.Furthermore, tilting movements of larger components, for example, can be prevented by supporting them at specific stable points on the support webs. The specific measures implemented for this purpose are not described in DE 10 2019 104 649 B4.

[0008] DE 10 2019 126 403 A1, also mentioned above, describes a method for loading a sheet storage device of a flatbed machine tool with a material sheet. The material sheet is to be fed to the flatbed machine tool for processing from a target position assigned to the processing in a machine coordinate system, and the flatbed machine tool comprises a camera system with at least one camera. The camera system is designed to generate images of the sheet storage device that are spatially calibrated to the machine coordinate system of the flatbed machine tool. The method comprises the following steps:

[0009] - Creating an image of the material board in the area of ​​the board storage device,

[0010] - Evaluation of the image recording to determine the actual table position in the machine coordinate system,

[0011] - Detecting a deviation of the determined actual sheet position from the target position and using the detected deviation to align and position the material sheet. A control system of the flatbed machine tool, in particular a laser control system, can detect the actual (actual) position (if it is, for example, within the tolerance range) and adapt a machining program (e.g., the cutting plan) to the actual position by means of transformation. According to DE 10 2019 126 403 A1, the target position can be specified manually or calculated at loading time depending on the support web configuration on the laser flatbed machine. Furthermore, the target position can be determined depending on the part nesting on the material sheet, in particular depending on parameters such as avoiding tipping parts, optimal support of the parts during the cutting process, avoiding slag splashes, and avoiding welding of parts to the base.Furthermore, the nesting of the parts to be produced can be subsequently adjusted, particularly optimized, depending on the loading position and the support web configuration. This can also be achieved depending on parameters such as avoiding tipping parts, optimal support of the parts, e.g., during the cutting process, avoiding slag splashes, and preventing parts from welding to the base. DE 102019 126 403 A1, again, remains open as to which specific measures are taken for this purpose.

[0012] Object of the invention

[0013] It is an object of the invention to efficiently increase process reliability during jet cutting of sheet metal parts and, in particular, to avoid collisions of a cutting head.

[0014] Description of the invention

[0015] This object is achieved according to the invention by a method according to claim 1 and a beam cutting machine having the features specified in claim 18. Advantageous variants and embodiments are specified in the respective subclaims and the description. According to the invention, a method for cutting out components from a sheet metal panel using a beam cutting machine with a cutting head is provided. The beam cutting machine is in particular a laser cutting machine with a laser cutting head. The beam cutting machine has a workpiece support with a plurality of support webs for the sheet metal panel, wherein the support webs can be arranged at previously known grid positions. The cutting head is movable relative to the workpiece support in order to cut out the components. As a rule, a support web is arranged at most grid positions, typically at least 90% of the grid positions, but not necessarily at all grid positions of the workpiece support.The support webs can each have a plurality of points for local support of the sheet metal. Typically, the support webs extend in a straight line, and the grid positions are aligned parallel to each other.

[0016] The procedure includes the following steps:

[0017] A) Specifying i) a nesting plan of components to be cut out on the sheet metal panel, ii) a machining program for controlling the cutting head during the cutting out of components arranged according to the nesting plan from the sheet metal panel, iii) tolerance fields of predetermined width for the positions of the support webs;

[0018] B) Detecting i) those grid positions at which a support web is present, ii) a position of a sheet metal panel arranged on the workpiece support;

[0019] C) Determine where the support webs are located relative to the sheet metal panel, in particular relative to the individual components to be cut out;

[0020] D) Calculating sets of interference contours that could arise from components of the specified nesting plan tilting on the support webs, whereby a set of interference contours is calculated for a plurality of positions of the support webs within their respective tolerance zones; E) Determining a set of effective interference contours from the calculated sets of interference contours;

[0021] F) Modifying the machining program so that, for the effective set of interference contours, a predetermined minimum distance between the cutting head and the interference contours of the components already cut free during the execution of the modified machining program is avoided;

[0022] G) Cutting out the components according to the modified machining program.

[0023] The nesting plan describes the position of the components to be cut out on the sheet metal panel. When the machining program is executed, the components would be cut out according to the nesting plan. To achieve this, the machining program defines a relative movement between the cutting head and the workpiece support. The nesting plan of the components can be specified implicitly by the machining program.

[0024] In practice, the support webs are often not arranged exactly at the grid positions. The actual position of a support web can deviate from the grid position, for example due to deformation. For example, support webs can be bent or worn. Likewise, holders for the support webs can be deformed or have a certain amount of play. Regardless of the underlying mechanism, it can therefore happen that one or more of the support webs are not in the intended (target) position, but extend in a vicinity thereof. The maximum expected deviation from the target position is described by the width of the tolerance field. It is therefore assumed that the support web is located within the tolerance field at the respective grid position. In other words, it is assumed that the support webs are located within the tolerance field of a specified width for the respective grid position.Typically, the tolerance fields are the same size for all grid positions. Especially with interchangeable support bars, it is not certain that a support bar is actually located at every grid position. Therefore, the grid positions at which support bars are present are recorded. Due to the specified tolerance field, the position of each support bar does not need to be determined precisely; it is sufficient to identify the grid positions at which a support bar is located.

[0025] The position of the sheet metal on the workpiece support can also vary. Therefore, the position of the sheet metal relative to the workpiece support is also recorded.

[0026] The grid positions of the support webs and / or the position of the metal sheet can be recorded using a camera. The camera can be mounted on a housing part of the beam cutting machine. The grid positions of the support webs and / or the position of the metal sheet can be recorded using a sensor device. The sensor device can be mounted on a housing part of the beam cutting machine. The sensor device can use radar, lidar, ultrasound, laser light section, inductive, or capacitive measuring methods for this purpose. The sensor device and / or the camera can be movably guided by means of a holding device.

[0027] Based on the previously determined data regarding the presence of support bars and the position of the sheet metal on the workpiece support, the locations where the sheet metal is supported by the support bars are determined. In particular, the location of the components arranged in the nesting plan is determined.

[0028] Depending on the size and position of a component, it can tilt around one of the support webs after being cut free (completely cut out). This can result in an interfering contour. The interfering contour describes in particular the area above the workpiece support into which a tilted or tilting component can protrude. In particular, the component can remain in a tilted position and protrude above the support surface of the workpiece support. The interfering contours can be calculated as the rotational solids of the tilting components. It can be assumed that a component tilts if its center of gravity is located beyond an outer support web on the component in question; otherwise it can be assumed that the component does not tilt, so no interfering contour is created. A component that is only supported by a single support web will usually tilt.

[0029] Since the positions of the support webs can vary, as explained above, the interference contours of the potentially tilting components are calculated for a large number of different support web positions within their respective tolerance zones. The positions of the support webs can, for example, be varied in specified increments within the tolerance zones. In particular, at least five positions can be mathematically checked for each support web. The limits of the tolerance zones are expediently included in this process. Preferably, all combinations of support web positions within their respective tolerance zones are successively checked for potential interference contours (for the selected number of positions per tolerance zone). Thus, a set of interference contours is determined for each considered combination of support web positions.

[0030] From the many sets of noise contours, a set of effective noise contours is determined, in which information from the individual sets is aggregated in a predefined manner. The set of effective noise contours is also referred to as the effective set of noise contours.

[0031] The set of effective interference contours can be determined from the calculated sets according to a specified criterion. In particular, the calculated interference contours of several sets can be superimposed in the effective set. For each potentially tilting component, the interference contours with the largest volume and / or the greatest height, depending on the position of the support webs, can be included in the effective set of interference contours.

[0032] Based on the set of effective interference contours, the

[0033] The machining program is modified so that the cutting head does not traverse the areas of potential interference contours. The machining program is adjusted to ensure that a minimum distance is always maintained between the cutting head and the interference contours of those components that have already been cut free in the modified machining sequence. It should be noted that before a component is completely cut out (freed), the area of ​​its potential interference contour can be traversed, since only free-cut components can tilt.

[0034] Finally, the components are cut out using the modified machining program. The previously described modification of the machining program reduces disruptions, especially collisions, when cutting out the components.

[0035] Overall, the method according to the invention increases productivity through a trouble-free cutting process without collisions and unplanned downtimes of the jet cutting machine. In particular, reduced machine wear can be achieved by avoiding nozzle collisions and reducing wear on the support webs. Furthermore, consequential damage to the cutting head, a movement unit, or, for example, bellows is avoided. Furthermore, the risk of injury during cutting is reduced, as less frequent collisions reduce the need for manual intervention in the machine. Furthermore, operating personnel are no longer permanently tied to the jet cutting machine. Downstream processes such as automatic unloading also benefit from the targeted prevention of tilting. Furthermore, the effort required for fine-tuning the machining program in upstream processes such as job planning and CAD / CAM programming can be reduced.Finally, increased cutting stability increases confidence in the cutting process. Overall, unplanned downtime is reduced, resulting in greater cost-effectiveness.

[0036] Steps A) and B) as well as substeps i) to iii) or i) and ii) of steps A) and B) can be performed in any order and / or at least partially simultaneously. During the execution of steps C) to F), setup or maintenance work can be performed on the jet cutting machine.

[0037] The method according to the invention is preferably carried out with a jet cutting machine according to the invention described below.

[0038] The workpiece support can be moved between a loading position and a processing position. This facilitates the positioning of the sheet metal panel on the workpiece support.

[0039] Preferably, the grid positions of the (existing) support bars and / or the position of the sheet metal panel are recorded when the workpiece support is in the loading position. The workpiece support is then usually clearly visible, for example, for a camera. Furthermore, the time spent moving the workpiece support to the processing position can be used to perform the subsequent process steps.

[0040] Preferably, steps D), E), and F) are performed at least partially while the workpiece support is being moved from the loading position to the processing position. This reduces the time until the jet cutting machine can begin cutting the components after the sheet metal sheet has been placed on the support.

[0041] In particular, the start of step G) can be delayed after the processing position has been reached until steps D) to F) have been completed. In order to maximize machine utilization, it is conventionally sought to avoid downtimes as far as possible. However, the method according to the invention can reduce operational interruptions during cutting to such an extent that a certain delay in the start of processing is reflected in an overall reduction in production time or higher productivity. Preferably, in step D), the sets of interfering contours are also calculated for various positions of the sheet metal sheet within a predetermined range relative to the detected position of the sheet metal sheet. Potentially occurring interfering contours are thus determined for various positions of the sheet metal sheet in the predetermined range around the detected position and in each case the various positions of the support webs.This allows inaccuracies in the detection of the position of the sheet metal panel to be compensated.

[0042] The set of effective interference contours can correspond to the calculated set of interference contours with the largest volume of the interference contours above the sheet metal and / or the maximum height of the interference contours. A worst-case scenario is thus assumed to adapt the machining program.

[0043] Alternatively, the set of effective interference contours can correspond to an enveloping contour of the interference contours of several calculated sets, in particular all calculated sets, of interference contours. In this way, several, preferably all, potentially occurring interference contours are used to adapt the machining program. The enveloping contour can be a convex hull of the calculated interference contours.

[0044] In step F), several modified variants of the machining program can be determined and one of the variants can be selected according to a specified criterion. This makes it possible to obtain a particularly effectively optimized machining program. At the same time, only few specifications or prior information are necessary to determine the variants of the machining program, since less good variants are sorted out and a more advantageous variant is selected instead. The criterion can, for example, include maximizing an integral of the distance of the cutting head to the interfering contours of the components that have already been cut free. The criterion can relate to the point in time in the machining program at which a component that represents a potential interfering contour is cut free. In particular, a variant of the machining program can be selected in which potential interfering contours are created as late as possible in the machining program.In step F), the order in which the components and / or partial contours of the components are cut out can be changed. Collisions with potentially tipping components can be avoided particularly easily and effectively in this way. In particular, for example, larger components can be cut out not all at once, but successively along several partial contours. Smaller components that fall down between the support webs after cutting out can be cut out in a specific 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 controlled in a time-synchronized manner with the occurrence of the small components or waste pieces.

[0045] In step F), the course of the travel paths can be changed for positioning movements without a cutting process, in particular so that components that have already been cut free are bypassed. Alternatively or additionally, the distance between the cutting head and the sheet metal panel can be increased and / or the cutting gas pressure can be reduced over components that have already been cut free. These measures can also be used to effectively reduce the risk of collision in a simple manner, usually at the expense of a slightly longer machining time. The aim is generally to reduce the length of travel paths over cut-free components, i.e. to bypass them wherever possible. If bypassing by changing the course is not possible, the additional measures mentioned can be taken.

[0046] In step F), an additional cutting of waste pieces can be provided. Thus, in step G), the waste pieces are cut. The respective parts of one of the waste pieces can fall through between the support webs and be disposed of, for example, via a conveyor system below the workpiece support, such as a (scrap) conveyor belt. It can be provided that in step F),

[0047] - Positions of connections of the components to the remaining grid of the sheet metal panel provided in the specified machining program are changed, and / or

[0048] - connections between the components and the remaining grid of the sheet metal panel provided for in the specified machining program are removed, and / or

[0049] - additional connections of the components to the remaining grid of the sheet metal panel are inserted.

[0050] These joints are also called "microjoints" or "nanojoints" and are subsequently separated (typically outside the processing area), either manually or by an unloading system. The aforementioned modifications allow these joints to be provided in the number necessary to prevent component tipping, while avoiding joints that exceed this number.

[0051] In step F), the nesting plan of the components on the sheet metal can be changed. To do this, individual components can be moved and / or rotated on the sheet metal, typically within specified limits. In particular, the components can be positioned so that they do not tilt on the support webs. This effectively and easily prevents collisions between the cutting head and tilted components.

[0052] In particular, the nesting plan can be modified to reduce the length of cutting paths over support bars. This reduces the wear on the support bars caused by the cutting beam.

[0053] The machining program can be modified in step F) such that grooving processes in the area of ​​support webs are reduced, or preferably avoided. For this purpose, the position of the grooving point relative to one of the components can be changed. Alternatively or additionally, this can be achieved by changing the nesting plan (i.e. changing the position and / or orientation of at least one of the components on the sheet metal panel). When grooving via support webs, there is a risk that the grooving process will not proceed as desired. In addition, wear on the support webs due to the grooving processes is reduced. The area of ​​a support web typically comprises the tolerance field at its grid position. An additional safety distance to the edge of the tolerance field can be specified.

[0054] It can be provided that, in the event of a collision of the cutting head with the sheet metal, with one of the components, or with a waste piece during the execution of step G), steps B)ii) to F) are performed again, and then step G) is continued for the remaining cutting operations with the newly modified machining program. During the collision, the sheet metal may shift on the workpiece support. This is compensated for by repeating the aforementioned steps. The workpiece support can be moved to the loading position for the repeated execution of step B)ii).

[0055] The scope of the present invention also includes a beam cutting machine with a cutting head, in particular a laser cutting machine with a laser cutting head, comprising

[0056] - a workpiece support with several support webs for a sheet metal panel, wherein the support webs can be arranged at previously known grid positions;

[0057] - a device, in particular a camera, for detecting those grid positions at which a support web is present and for detecting a position of a sheet metal panel arranged on the workpiece support; and

[0058] - a control device for controlling the cutting head, wherein a nesting plan of components on a sheet metal panel, a machining program for cutting the components from the sheet metal panel, and a width of tolerance fields for the positions of the support webs can be stored in the control device, and wherein the control device is configured (programmed) to carry out steps B) to G) of a method according to one of the preceding claims. The jet cutting machine enables the method according to the invention to be carried out according to the specification of the nesting plan, the machining program, and the tolerance field widths. The nesting plan can be defined implicitly by the machining program.

[0059] The jet cutting machine may have further features described in connection with the method according to the invention.

[0060] To perform step B), the control device can use the detection device (the camera). To perform step G), the control device controls the cutting head according to the modified machining program. The workpiece support can be movable between a loading position and a machining position.

[0061] The control device can be a local control device for a single jet cutting machine. Alternatively, the control device can be a central control device for a plurality of jet cutting machines. It is also conceivable for the control device to be distributed across local and central control components.

[0062] Further features and advantages of the invention will become apparent from the description, the claims, and the drawings. According to the invention, the above-mentioned and further-described features can be used individually or in combination in any convenient way. The embodiments shown and described are not intended to be exhaustive, but rather are exemplary in nature for describing the invention.

[0063] Detailed description of the invention and drawing

[0064] The invention is illustrated in the drawing and described using exemplary embodiments. In the drawing: Fig. 1 shows a schematic perspective view of a jet cutting machine according to the invention with a workpiece support on which a metal sheet is arranged, the workpiece support being in a loading position and being captured by a camera;

[0065] Fig. 2 shows a section of the jet cutting machine of Figure 1 with the workpiece support in a processing position and a movable cutting head, wherein a support web is missing at a grid position of the workpiece support, in a schematic sectional view;

[0066] Fig. 3 shows the workpiece support of the jet cutting machine of Figure 2, showing that the positions of the support webs can vary within certain limits at the respective grid positions, in a schematic side view;

[0067] Fig. 4 a sheet metal panel with a nesting plan of components to be cut out, in a schematic plan view;

[0068] Fig. 5 shows a component resting stably on three support webs, in a schematic side view;

[0069] Fig. 6 shows the component of Figure 5, wherein the component tilts due to a displacement of the support webs relative to one another and of the component relative to the support webs, with representation of a resulting interference contour, in a schematic side view;

[0070] Fig. 7 is a schematic flow diagram of a method according to the invention for cutting out components from a sheet metal panel;

[0071] Fig. 8 shows a convex hull of interfering contours of a component that tilts in different ways depending on the support web position, in a schematic side view. Figure 1 shows a beam cutting machine in the form of a laser cutting machine 10. A workpiece support 12 is located in a loading position outside a housing 14. A metal sheet 16 is arranged on the workpiece support 12, with a nesting plan of components 18 to be cut out being drawn on the metal sheet 16 in Figure 1. In practice, the nesting plan is typically not shown on the metal sheet 16, but rather stored in a control device 20. A camera 22 records the workpiece support 12 and the metal sheet 16. The camera 22 is attached to the housing 14 here.

[0072] In Figure 2, the workpiece support 12 is in a processing position within the housing 14 (not shown in Figure 2, see Figure 1). A laser cutting head 24 is movable above the workpiece support 12 along three axes 26, 28, 30. The laser cutting head 24 can have a nozzle 32 from which a laser beam and a cutting gas jet emerge to cut out the components 18.

[0073] Figure 2 shows that the workpiece support 12 has a plurality of support webs 34 running essentially parallel to one another; here, the support webs 34 each extend perpendicular to the plane of the drawing. The support webs 34 can have tips (not shown in detail) for point-like contact with the sheet metal panel 16. The support webs 34 are arranged interchangeably at predetermined grid positions 36, spaced from one another. It can happen that no support web 34 is present at one or more of the grid positions 36. For example, in Figure 2, the support web is missing at the fourth grid position from the left. The grid positions 36 can be defined by holders for the support webs 34.

[0074] A conveyor belt 38 can be arranged below the support webs 34. The conveyor belt 38 can be used to remove small components or waste pieces that have fallen through between the support webs 34.

[0075] Figure 3 illustrates that the actual position of each support bar

[0076] 34 at its grid position 36 can vary within certain limits. This can be caused, for example, by deformation, damage, or play in the holders. The possible positions of the support webs 34 can be described by tolerance zones 40, which have a specific width 42 depending on the type of workpiece support 12 and support webs 34. In Figure 3, the outermost positions of a support web 34 within its respective tolerance zone 40 are shown in dashed lines.

[0077] A method for cutting out the components 18 from the sheet metal panel 16 is described with additional reference to the flow chart shown in Figure 7 and the nesting plan of Figure 4 with four exemplary components 18.1-18.4.

[0078] First, a nesting plan is specified (step 102); the arrangement of components 18.1-18.4 according to the original nesting plan is shown in Figure 4 with solid lines. In addition, a machining program is specified (step 104), which controls the laser cutting machine 10 to cut out components 18.1-18.4 according to the specified nesting plan. The nesting plan can be defined implicitly by the machining program or stored separately. The nesting plan can be defined relative to sheet metal panel 16 or, alternatively, relative to workpiece support 12. The machining program and the nesting plan are stored in the control device 20. In addition, the widths 42 for the tolerance zones 40 are specified (step 106) and stored in the control device 20.

[0079] While the workpiece support 12 is in the loading position (see Figure 1 ), the metal sheet 16 is placed onto the workpiece support 12 (step 108). For this purpose, the workpiece support 12 can have been moved into the loading position in a step 107. Typically before or, in special cases, after the metal sheet 12 has been placed on the workpiece support 12, the camera 22 is used to detect the grid positions 36 at which a support web 34 is actually located (step 110). The camera 22 also detects where the metal sheet 16 is located on the workpiece support 12 (step 112). Instead of the camera 22 or in addition to it, tactile and / or optoelectronic sensors such as light barriers could also be provided for detecting the positions of the support webs 34 and the metal sheet 16 (not shown in detail).From this information, the position of the sheet metal panel 16 relative to the workpiece support 12, in particular relative to the grid positions 36, is determined in a step 114. Steps 110 and 112 are also performed in the illustrated embodiment while the workpiece support 12 is in the loading position.

[0080] The originally specified machining program may, for example, stipulate that the components are to be cut out in the order 18.1, 18.2, 18.3 and 18.4, see Figure 4.

[0081] If the support webs 36 and the metal sheet 16 are in their desired positions, the support of the component 18.1 shown in Figure 5 may result from three support webs 34.1-34.3. In contrast, if the metal sheet 16 with the component 18.1 is aligned with the workpiece support 12 in a slightly offset manner (here to the left), and the support web 34.2 is shifted toward the support web 34.1 and the support web 34.3 is shifted away from the support webs 34.1 and 34.2, the situation shown in Figure 6 may arise, in which the component 18.1 is supported only by the two support webs 34.1 and 34.2, but not by the support web 34.3. Furthermore, since the center of gravity of component 18.1 lies between the support webs 18.2 and 18.3, component 18.1 would tilt after cutting free. This could result in an interfering contour 44 with a height of 46.

[0082] Similarly, interference contours could also arise for the other components 18.2-18.4 and / or other displacements of the support webs 34. Therefore, in a step 116, for different positions of each support web 34 within its tolerance zone 40 and preferably for different positions of the sheet metal panel 16 relative to the workpiece support 12, it is calculated which components 18 in the respective configuration potentially tilt after free cutting. In particular, the shape of the interference contour 44 potentially arising during tilting and its possible height 46 can be calculated. In this way, a set of interference contours 44 is obtained for each combination of the various support web positions within the respective tolerance zones 40 and the various positions of the sheet metal panel 16.

[0083] The information about the interference contours 44 of the different sets is summarized in a step 118 in a set of effective interference contours (hereinafter also referred to as effective set).

[0084] In the set of effective interference contours, the maximum height 46 of its potentially occurring interference contour 44 can be stored for each component 18 or 18.1-18.4. Alternatively or additionally, a maximum volume of a potentially occurring interference contour 44 can be stored for each component 18 or 18.1-18.4 in the effective set.

[0085] In the effective set of interference contours, for each component 18 or 18.1-18.4, an envelope contour 47 of the potentially occurring interference contours 44, 44' for the respective component can be stored as an effective interference contour, see Figure 8. Figure 8 shows, for the same component 18, that this component 18 can tilt in a different way depending on the assumed position of a support web 34 (shown in dashed or dash-dotted lines). The resulting interference contours 44 or 44' above the workpiece support 12 can be enclosed by the envelope contour 47 in the smallest convex space; in other words, the envelope contour 47 can be the convex hull of the interference contours 44.

[0086] For components that are not expected to tip over in all configurations considered, corresponding information can be stored in the effective set.

[0087] Based on the effective set of interference contours, the machining program is modified in a step 120 such that the laser cutting head 24 always maintains a predetermined minimum distance, typically a few millimeters or a few centimeters, from the interference contours stored in the effective set of components 18, 18.2-18.4 already cut free in the machining process. To determine a suitably modified machining program, several variants of modified machining programs can be determined, and from these, the best variant is selected according to a predetermined criterion.

[0088] In the example shown (see Figure 4), in the originally specified machining program, a travel path 48 (dotted line) of the laser cutting head 24 between the cutting out of components 18.2 and 18.3 runs over the already cut-out component 18.1 (solid line), and in particular in the area of ​​its interfering contour 44 (see Figure 6), to a piercing point 50. Therefore, there is a risk of a collision between the laser cutting head 24 and the tilted component 18.1. The machining program is modified in such a way that this collision is avoided. Various approaches are possible for this purpose, which can be applied individually or in combination depending on the situation.

[0089] One possible modification of the machining program is to alter the path of travel 48 so that it passes component 18.1 and its interfering contour 44. Such a modified path 48' is shown in dash-dotted lines in Figure 4. Alternatively or additionally, the height of the laser cutting head 24 above the sheet metal panel 16 could be increased during the positioning movement along the path 48 or 48' and / or the pressure of the cutting gas exiting the nozzle 32 could be reduced.

[0090] To prevent component 18.1 from tipping, its position and / or orientation on the sheet metal panel 16 could be changed. In other words, the nesting plan can be changed. Figure 4 shows a rotated arrangement of component 18.1 shifted in the direction of axes 26, 28, which increases its overlap with support webs 34.1 and 34.3 (see Figures 5 and 6). By changing the nesting plan, it can also be ensured that cutting lines do not run along one of the support webs 34.

[0091] In addition, or instead, a connection 52 (a so-called microjoint) of component 18.1 to a residual skeleton 54 could be inserted during cutting. This connection 52 initially holds component 18.1 to the residual skeleton 54 and is severed after all components 18.1-18.4 have been cut out. Accordingly, depending on the situation, the positions of connections to the residual skeleton 54 could be changed, and unnecessary connections to the residual skeleton 54 could also be removed.

[0092] It is also conceivable to change the order in which components 18.1-18.4 are cut out. Here, it could be planned to cut out the components in the order 18.2, 18.1, 18.3, 18.4. This could potentially also reduce the length of the positioning movements without a cutting process (compare travel paths 48, 48').

[0093] For potentially tipping waste pieces, for example, a waste piece 56 inside component 18.3, sets of interference contours can also be calculated in step 116 and taken into account in the effective set in step 118. To avoid collisions with tipping waste pieces 56, the machining program can be modified in step 120 so that these waste pieces 56 are cut into smaller pieces that fall safely between the support webs 34. These can then be removed via the conveyor belt 38 (see Figure 2).

[0094] In step 120, the positions of piercing points 50 could also be changed to prevent piercing operations from occurring over support ribs 34. This does not directly contribute to collision avoidance in the current cutting process, but it does reduce wear on the support ribs 34. The tolerance zones 40 thus remain smaller, and fewer interference contours are subsequently determined, since the positions of the support ribs 34 only vary within tolerance zones of smaller width.

[0095] Steps 114, 116, 118, and 120 can be performed at least partially while the workpiece support 12 is moved from the loading position (see Figure 1) to the machining position (see Figure 2) in a step 121. Preferably, steps 114, 116, 118, and 120 are performed by the control device 20. The control device is programmed accordingly. Then, in a step 122, the components 18.1-18.4 are cut out according to the modified machining program. If the execution of steps 114 to 120 has not yet been completed when the machining position is reached, the start of cutting out is delayed until the completion of step 120.

[0096] If, contrary to expectations, a collision should occur during cutting, steps 112 to 120 can be repeated; see the dashed arrow in Figure 7. To repeat step 112, the workpiece support 12 can be moved to the loading position (repeat step 107). Before the remaining components are cut out in the continued step 122 with the newly modified machining program, the workpiece support 12 is returned to the machining position (repeat step 121).

[0097] In summary, the invention relates to a method for cutting out sheet metal parts. A sheet metal panel rests on several support webs. It is determined which sheet metal parts could tilt during cutting. This takes into account which support webs are actually present. A machining program for cutting out the sheet metal parts is modified to avoid collisions between a cutting head and tilted sheet metal parts. For this purpose, interference contours caused by the potentially tilting sheet metal parts are calculated for various positions of the support webs in a vicinity of their target position. Information on the calculated interference contours for the various assumed support web positions is aggregated in a predetermined manner. The modified machining program prevents the cutting head from penetrating the areas of the aggregated interference contours of sheet metal parts already cut free during the program run. List of reference symbols

[0098] Laser cutting machine 10

[0099] Workpiece support 12

[0100] Housing 14

[0101] Sheet metal plate 16

[0102] Components 18; 18.1-18.4

[0103] Control device 20

[0104] Camera 22

[0105] Laser cutting head 24

[0106] Axes 26, 28, 30

[0107] Nozzle 32

[0108] Support bars 34; 34.1-34.3

[0109] Grid position 36

[0110] Conveyor belt 38

[0111] Tolerance fields 40

[0112] Width 42

[0113] Interference contour 44, 44'

[0114] Height 46 of the interference contour 44

[0115] Envelope contour 47

[0116] Travel 48, 48'

[0117] Insertion point 50

[0118] Connection 52

[0119] Remaining skeleton 54

[0120] Waste piece 56

[0121] Specifying 102 a nesting plan

[0122] Specifying 104 a machining program

[0123] Specify 106 of widths 42 of tolerance fields 40

[0124] Moving 107 the workpiece support 12 into a loading position

[0125] Placing 108 a metal sheet 16 Detecting 110 grid positions 36 of the support webs 34

[0126] Detecting 112 a position of the sheet metal plate 16 on the workpiece support 12

[0127] Determining 114 positions of the support webs 34 relative to the sheet metal panel 16

[0128] Calculate 116 sets of interference contours

[0129] Determining 118 a set of effective interference contours

[0130] Changing 120 of the editing program

[0131] Moving 121 the workpiece support 12 into a machining position

[0132] Cutting out 122 of the components 18

Claims

Patent claims 1. A method for cutting components (18; 18.1-18.4) from a sheet metal panel (16) using a beam cutting machine with a cutting head, in particular a laser cutting machine (10) with a laser cutting head (24), wherein the beam cutting machine has a workpiece support (12) with a plurality of support webs (34; 34.1-34.3) for the sheet metal panel (16), wherein the support webs (34; 34.1-34.3) can be arranged at previously known grid positions (36); wherein the method comprises the following steps: A) Predetermining i) a nesting plan of components (18; 18.1-18.4) to be cut out on the sheet metal panel (16), ii) a machining program for controlling the cutting head during the cutting out of components (18; 18.1-18.4) arranged according to the nesting plan from the sheet metal panel (16), iii) tolerance fields (40) of predetermined width (42) for the positions of the support webs (34; 34.1-34.3); B) detecting i) those grid positions (36) at which a support web (34; 34.1-34.3) is present, ii) a position of a metal sheet (16) arranged on the workpiece support (12); C) Determining where the support webs (34; 34.1-34.3) are located relative to the sheet metal panel (16), in particular relative to the individual components (18; 18.1-18.4) to be cut out; D) Calculating sets of interference contours (44, 44') which could arise due to components (18; 18.1-18.4) of the given nesting plan tilting on the support webs (34; 34.1-34.3), wherein for a plurality of positions of the support webs (34; 34.1-34.3) within their a set of interference contours (44, 44') is calculated for each of the respective tolerance fields (40); E) determining a set of effective interference contours from the calculated sets of interference contours (44, 44'); F) modifying the machining program so that, for the set of effective interference contours, the distance between the cutting head and the interference contours of the components (18; 18.1-18.4) already cut free during the execution of the modified machining program is avoided; G) Cutting out the components (18; 18.1-18.4) according to the modified machining program.

2. Method according to claim 1, wherein the detection of the grid positions (36) of the support webs (34; 34.1-34.3) and / or the position of the metal sheet (16) is carried out with a camera (22).

3. Method according to one of the preceding claims, wherein the workpiece support (12) can be moved between a loading position and a processing position.

4. Method according to claim 3, wherein the detection of the grid positions (36) of the support webs (34; 34.1-34.3) and / or the position of the metal sheet (16) takes place 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 carried out at least partially while the workpiece support (12) is moved from the loading position to the processing position.

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

7. Method according to one of the preceding claims, wherein in step D) the sets of interference contours (44, 44') are also calculated for different positions of the metal sheet (16) within a predetermined range relative to its detected position.

8. Method according to one of claims 1 to 7, wherein the set of effective interference contours corresponds to the calculated set of interference contours with a largest volume of the interference contours above the sheet metal panel (16) and / or a maximum height of the interference contours.

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

10. Method according to one of the preceding claims, wherein in step F) several modified variants of the machining program are determined and one of the variants is selected according to a predetermined criterion.

11. Method according to one of the preceding claims, wherein in step F) an order in which the components (18; 18.1-18.4) and / or partial contours of the components (18; 18.1-18.4) are cut out is changed.

12. Method according to one of the preceding claims, wherein in step F) for positioning movements without a cutting process the course of the travel paths (48, 48') is changed, in particular so that components (18; 18.1-18.4) are bypassed, and / or wherein a distance of the cutting head to the sheet metal panel (16) is increased over components (18; 18.1-18.4) that have already been cut free, and / or a cutting gas pressure is reduced.

13. Method according to one of the preceding claims, wherein in step F) an additional cutting of waste pieces (56) is provided.

14. Method according to one of the preceding claims, wherein in step F) Positions of connections (52) of the components (18; 18.1-18.4) to the residual grid (54) of the sheet metal panel (16) provided in the specified machining program are changed, and / or connections (52) of the components (18; 18.1-18.4) to the residual grid (54) of the sheet metal panel (16) provided in the specified machining program are removed, and / or additional connections (52) of the components (18; 18.1-18.4) to the residual grid (54) of the sheet metal panel (16) are inserted.

15. Method according to one of the preceding claims, wherein in step F) the nesting plan of the components (18; 18.1-18.4) on the sheet metal panel (16) is changed, in particular so that the length of cutting paths over support webs (34; 34.1-34.3) is reduced.

16. Method according to one of the preceding claims, wherein the machining program is modified in step F) such that piercing operations in the region of support webs (34; 34.1-34.3) are reduced, preferably avoided.

17. Method according to one of the preceding claims, wherein in the event of a collision of the cutting head with the sheet metal panel (16), with one of the components (18; 18.1-18.4) or with a waste piece (56) during the execution of step G), steps B)ii) to F) are carried out again and then step G) is continued for the remaining cutting operations with the newly modified machining program.

18. Beam cutting machine with a cutting head, in particular a laser cutting machine (10) with a laser cutting head (24), comprising a workpiece support (12) with a plurality of support webs (34; 34.1-34.3) for a metal sheet (16), wherein the support webs (34; 34.1-34.3) can be arranged at previously known grid positions (36); a device, in particular a camera (22), for detecting those grid positions (36) at which a support web (34; 34.1-34.3) is present, and for detecting a position of a sheet metal panel (16) arranged on the workpiece support (12); and a control device (20) for controlling the cutting head, wherein a nesting plan of components (18; 18.1-18.4) on a sheet metal panel (16), a machining program for cutting out the components (18; 18.1-18.4) from the sheet metal panel (16) and a width (42) of tolerance fields (40) for the positions of the support webs (34; 34.1-34.3), and wherein the control device (20) is configured to carry out steps B) to G) of a method according to one of the preceding claims.

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