METHOD AND SYSTEM FOR AUTOMATICALLY CUTTING PIECES IN A FLEXIBLE MATERIAL PACKAGED IN ROLL FORM

Abstract

The invention relates to a method and system for automatically cutting parts in a flexible material packaged in roll form, comprising the successive steps of preparing an initial layout (S1), spreading (S2) a layer of flexible material on a cutting table, initiating (S5) the automatic cutting of parts in the spread material according to the initial layout, during cutting, upon receiving an activating event (Evt) for which the layout of at least one of the parts is no longer suitable for the cutting environment or for which it is necessary to modify the list of parts in the initial layout, preparing a list of parts to be retained (S6), and automatically preparing a new layout (S7) taking into account the position of the parts to be retained and calculating new positions for all or part of the other parts without taking into account their positions in the initial layout.

Description

METHOD AND SYSTEM FOR AUTOMATICALLY CUTTING PIECES IN A FLEXIBLE MATERIAL PACKAGED IN ROLL FORM Field of invention The invention relates to the general field of automatic cutting of parts from a flexible material packaged in roll form. More particularly, it relates to the management of triggering events that occur during the cutting of the parts and that can affect the quality and efficiency of the cutting process. The fields of application of the invention are, in particular, the clothing and furniture industries. State of the art Automatic cutting of parts in a flexible material is normally performed on a conveyor-driven cutting machine piloted from a control station. The cutting process is carried out as follows. The operator receives a pre-prepared list of cutting jobs to be updated at the control station. Each of these jobs contains all the information necessary to update a cut, namely: the placement of the pieces to be cut and the material on which the cut will be updated. The materials used (flexible material) are generally packaged in rolls, which are loaded into the cutting machine's supply module. The material is then progressively conveyed via a conveyor to the different modules of the cutting machine: a cutting module where the pieces are cut, and an unloading module where the operator collects the cut pieces. In the case of a cutting machine that processes printed fabrics, a material acquisition module is also provided to scan the fabric before it reaches the cutting module. Once the material has been transported to the cutting module, the system knows the relative position of the pieces thanks to a pre-set layout stored at the cutting work area. To cut these pieces correctly on the material, the operator must also position this layout on the material. The preparation for workpiece placement is carried out in a way that optimizes material consumption while also achieving a high-quality cut. To this end, restrictions can be imposed using the cutting support. For example, the usable web width may limit the workpiece placement area. Similarly, the type of material used may impose a minimum proximity distance between certain workpieces. In addition to these constraints imposed by the cutting support, designers and modelers can impose further constraints during the creation phase. This might include, for example, adhering to the straight grain of the fabric, which imposes defined twist values, or, in the case of printed fabrics, connection constraints that impose a positional dependency between the parts. Once the operator starts production at the cutting machine's control station, the system will automatically activate the supply module using the material data from the first cutting job on the list. At the supply module, the operator can load the roll corresponding to the delivered material. Depending on the machine's options, the operator can specify the material's orientation and visible side. This information will be updated either at the control station or in the supply module. Once this stage is validated, the material is transported to the cutting module while passing through the acquisition module. This module digitizes the material spread on the cutting table and provides the operator with its current characteristics. Once the material has been transported to the cutting module, the operator positions the placement in the correct location on it using the image provided by the acquisition module or with a pointer embedded in the cutting head, and the cutting can begin. During production, several discrepancies can arise between the theoretical information (previously provided during the cutting process) and the actual information (recorded by the operator or specific to the roll during cutting), rendering the layout preparation obsolete. If these discrepancies are not addressed, they can negatively impact the quality of the cut or the overall efficiency. To mitigate these issues, various adjustments to the production setup can be implemented. Furthermore, during the cutting of a placement, it is possible that the roll of material will run out and that the available material will no longer be sufficient to finish cutting the placement that has been started. To overcome this problem, one known solution is to ask the operator to show the end of the current roll to divide the placement into two portions to avoid the change zone between rolls. This prior art solution is illustrated in Figures 1A to 1C. Figure 1A depicts a plurality of parts P1 to P10 from a stack in the cutting process. Parts P1 to P3 have already been cut from the current roll Re (and have reached the unloading module), part P4 is being cut, while parts P5 to P10 are not yet cut (or are partially cut, or even completely cut). Furthermore, it can be seen in Figure 1A that parts P5 and P6 are positioned at the end of the current roll Re (from which parts P1 to P4 are being cut), and parts P7 to P10 are positioned beyond the end of the current roll. Based on this information, the operator defines a roll change zone Z, represented in Figure 1B. As illustrated in Figure 1C, parts P5 to P7 located in this zone Z are not cut on the current roll Re and are placed on the next roll Rs to be cut there. More specifically, the placement of parts P1 to P1O is split in two, with parts P5 to P1O being moved to the next roll Rs for cutting. This prior art solution allows limiting the number of pieces that must be rejected during roll changeover. However, as clearly illustrated in Figure 1C, having to divide the existing layup into two parts can result in a significant loss of material. This solution is also used to avoid defective areas in the material: the beginning of the defective area is assimilated to the end of the current roll, and the end of the defective area is assimilated to the beginning of the next roll; the space between the two rolls is considered as a defective area. In practice, if a defect is detected in the defective area before the pieces are trimmed, the operator may want to avoid trimming pieces that will be unusable later. The known solution is to split the layup into two pieces, as described earlier for the roll end problem, to avoid the defective area. However, this solution presents the same drawbacks mentioned previously, namely, a significant loss of material. Furthermore, during the unloading of the parts, the operator may notice a defect that renders a part unusable. In this case, they have the option to reject it. Once the layout has been cut and completely unloaded, all rejected parts are recut and assigned to a new layout. This solution allows for the recutting of parts with quality issues, thus ensuring the production of all desired parts in a usable format. However, the lower the number of rejected parts, the greater the risk of material loss. Furthermore, having to wait for the new setup to recut these rejected parts can result in lost production time. More generally, the setup prepared before production and given in the cutting job is usually sufficient for the cutting process. However, it often happens that this setup needs to be modified to account for the problems mentioned above. Currently, the proposed solutions to overcome these problems consist of adaptations to the existing initial setup: the position of the parts is slightly shifted, or the part is rejected for cutting again in a new, additional setup. These adaptations have the advantage of avoiding quality problems. On the other hand, the modified placement results in a significant loss of material and an additional production time. Disclosure of the invention The objective of the present invention is, therefore, to propose a cutting process that does not have the aforementioned drawbacks when an activating event occurs during the placement cutting. According to the invention, this objective is achieved by means of a method for automatically cutting pieces in a flexible material packaged in roll form, comprising the successive steps of: a) prepare an initial layout for a list of pieces to be cut out of the flexible material; b) spread at least one layer of flexible material on a cutting table; c) start the automatic cutting of the pieces in the material spread on the cutting table according to the initial placement; d) during the initial placement cut, upon receiving a triggering event for which the placement of at least one of the parts no longer fits the cutting environment or for which the initial placement parts list needs to be modified, preparing a list of parts to be maintained; and e) automatically prepare a new arrangement taking into account the position of the parts to be maintained and calculate new positions for all or part of the other parts - called parts to be repositioned - without taking into account their positions in the initial arrangement. The method according to the invention is remarkable because it provides, in case of receiving an activating event during the placement cut, automatically preparing a list of parts to be maintained, then preparing a new placement different from the initial placement, this new placement takes into account the position of the parts to be maintained and calculates new positions for all or part of the other parts to be repositioned. Thus, in the event of detecting a roll end or a cutting defect, for example, the method according to the invention proposes updating a recalculation of the placement of all or some of the other parts to be repositioned in order to generate a new, optimized placement that allows for significant material savings. By new placement, we mean a placement of the parts to be repositioned in their entirety, prepared without regard to the position of the parts defined in the initial placement. In particular, this new placement is not merely a simple optimization of the initial placement. Furthermore, the method according to the invention allows for significant productivity gains insofar as it is possible to maintain a minimum cutting time during which the new placement is generated, thus avoiding any production stoppage. Preferably, step e) is followed by step f) of automatically cutting the pieces in the material spread on the cutting table according to the new placement. The new arrangement prepared in step e) may include all or part of the pieces from the initial arrangement that remain to be cut. In this case, the new arrangement prepared in step e) may also include one or more pieces for which the arrangement is no longer adapted to the cutting environment. Preferably, step d) also includes determining the number of retained parts remaining to be cut, based on an assessment of their cutting time and the time required to calculate the new placement. In this case, the time required to calculate the new placement is advantageously less than the assessment of the cutting time for the remaining retained parts. Again, preferably, the selection of the pieces for the new placement from among all the pieces of the initial placement that still need to be cut out is updated, complying with any placement restrictions of those pieces. The triggering event can be chosen from: a detection of the end of the roll in which the material spread on the cutting table is packaged, a detection of a defect in the material spread on the cutting table, and a detection of a defect in a cut piece that needs to be cut again. When the triggering event consists of detecting the end of the roll on which the material spread out on the cutting table is packaged, step e) may comprise establishing a first placement of pieces on the end of the roll, and a second placement of the remaining pieces on another roll of material. When the triggering event consists of the detection of a defect in the material spread on the cutting table, step e) may comprise the exclusion of the area of ​​the spread material on which the defect is located in order to establish the new placement. When the triggering event consists of the detection of a defect in a cut piece that needs to be cut again, step e) may comprise adding the defective piece to the new placement. Advantageously, the new placement of stage e) is designed to minimize any loss of productivity. To achieve this, stage e) can be updated without interrupting the cutting of the remaining parts to be trimmed according to the initial placement. Also advantageously, stage e) of preparing the new placement is carried out iteratively in order to obtain the highest possible efficiency index. Step c) may include a preliminary step of modifying the initial placement to generate a current placement of the pieces on the extended material that takes into account the current characteristics of the material. The invention also relates to a system for automatically cutting parts from a flexible material packaged in roll form, comprising: - means to prepare an initial placement of a list of pieces to be cut out in the flexible material; - a cutting table on which at least one layer of flexible material can be spread; - means for automatically cutting the pieces in the material spread on the cutting table according to the initial placement; - means to receive, during the initial placement cut, a triggering event for which the placement of at least one of the pieces no longer fits the cutting environment or for which the list of pieces in the initial placement needs to be modified; and - means to automatically prepare a list of parts to be maintained and a new placement taking into account the position of the parts to be maintained and calculate new positions for all or part of the other parts - called parts to be repositioned - without taking into account their positions in the initial placement. Brief description of the drawings [Figs. 1A-1C] Figures 1A to 1C already described illustrate an example of roll end management according to the state of the art. [Fig. 2] Figure 2 is a schematic view of the different modules of a cutting system for the implementation of the method according to the invention. [Fig. 3] Figure 3 is a flow diagram representing different stages of the method according to the invention. [Figs. 4A-4B] Figures 4A and 4B illustrate an example of implementation of the method according to the invention after detection of the end of the roll. [Figs. 5A-5B] Figures 5A and 5B illustrate an exemplary implementation of the method according to the invention after the detection of a defect in the material. [Figs. 6A-6B] Figures 6A and 6B illustrate an exemplary implementation of the method according to the invention after the detection of a defect in a cut piece that needs to be cut again. [Figs. 7A-7B] Figures 7A and 7B illustrate another exemplary implementation of the method according to the invention after the detection of a defect in a cut piece that needs to be cut again. [Figs. 8A-8C] Figures 8A to 8C illustrate an exemplary implementation of step d) of the method according to the invention, which consists of preparing a list of parts to be maintained. [Figs. 9A-9C] Figures 9A to 9C represent different stages of an exemplary implementation of step e) of the method according to the invention, which consists of preparing a new placement. Description of the modalities The invention relates to the automatic cutting of a plurality of pieces in a flexible material packaged in roll form by means of a cutting system as shown in Figure 2. In a known way, such a cutting system 2 can be composed of four modules through which the material passes, namely (from top to bottom in the direction of advance F of the material): a supply module 4 placed at one end of the cutting table 6, an acquisition module 8 (optional), a cutting module 10 and a discharge module 12 positioned at the other end of the cutting table. The supply module 4 is designed to receive the material to be cut, packaged in roll form. The acquisition module 8 is an optional module designed to scan the material spread out on the cutting table. The cutting module 10 comprises a mobile gantry 10a on which a cutting tool is mounted to update the cutting of the parts. The unloading module 12 is used by the operator to unload the cut parts from the table. The flexible material to be trimmed is conveyed to the cutting table 2 by a conveyor from the supply module 4 to the discharge module 12. The cutting system 2 also comprises a control station 14 which allows the operator to program a pilot of the different modules according to the material to be trimmed (cut) and the cutting jobs to be updated. In practice, the operator receives at control station 14 from a computer workstation 15 the information necessary to update a cut, namely (for each of the cutting jobs): an initial placement of a list of pieces to be cut and a material on which the cut will be updated. The flexible material in a cutting job represents the fabric from which the pieces are to be cut. Each material is associated with a set of pre-registered technical characteristics (in particular, the color, the description of any pattern, the width of the strip, etc.). Figure 3 is a flow diagram of the different stages of the method according to the invention for automatically cutting parts in a flexible material packaged in roll form, these different stages being implemented in particular using a cutting system as described in relation to Figure 2. The first stage of the method consists of preparing an initial layout of a list of pieces to be cut out of the flexible material. The placement is prepared manually or automatically, most often by a dedicated operator (different from the one who operates the cutting system), to optimize material consumption as much as possible but also to obtain a high-quality cutting result. As is well known, placement takes into account the limitations imposed by the cutting support, such as the width of the strip (which imposes a limitation on the placement area) and the type of material used (which imposes a minimum proximity distance between the pieces), but also the restrictions imposed by the designer and / or pattern maker, such as, for example, complying with the straight grain of the fabric and, in the case of a printed fabric, the connection restrictions between the pieces and the pattern stitch. In particular, in the case of a material consisting of a printed fabric, the initial placement is prepared taking into account the connection limitations between the pieces. For example, reference can be made to patent application FR 20 02947 filed on March 26, 2020, by the applicant, which describes a method for preparing a piece placement with piece placement restrictions in a printed fabric. The next stage S2 of the method according to the invention consists of spreading a layer of material to be cut on the cutting table. Typically, once the operator has started production at the control station, the cutting system will automatically activate the supply module based on the material data contained in the first cutting job on the list. At the supply module, the operator can load the roll corresponding to the material provided. This supply module is typically equipped with sensors and actuators to ensure the roll unwinds smoothly and the fabric is tension-free, crease-free, and properly aligned. This module is also typically equipped with a fabric presence detector. This detector can identify the end of a roll. Measuring fabric tension also allows for end-of-roll detection if the fabric end is stuck to the roll's central core. Next, the material is transported on the cutting table to the cutting module. Depending on the system configuration, the fabric may pass through an acquisition module where new information about the material is recorded. This acquisition module could be a scanner that records and analyzes an image of the material, a simple detector placed on the fabric's selvage that detects a mark indicating the presence of a defect in the fabric, or any other device that provides information about the material before cutting (stage S3). This S3 stage allows for the accounting of any discrepancies between the theoretical material information (previously provided during the cutting process) and the actual information observed by the operator or specific to the roll being cut. These discrepancies are due to printing defects, fabric placement errors on the cutting table, variations in thread density on the loom, and / or fabric deformations that can result in irregularities in the pattern repeat. If these differences are not taken into account, they can affect the quality of the cut result. Therefore, the initial placement (step S4) can be automatically modified or adjusted to correspond with the actual position of the fabric spread on the cutting table. An example of modifying the initial placement is described in publication EP 0,759,708. The next step S5 of the method according to the invention then consists of initiating the cutting of the initial placement (possibly modified during step S4). This operation is carried out at the level of the cutting module of the cutting system. During this stage, the material is moved over the cutting table and the different pieces are cut according to the possibly modified initial placement. When the cut pieces reach the level of the cutting system's unloading module, they are collected by the operator. During or at the end of this S5 stage, an Evt triggering event may occur. These triggering events include: detection of the end of the roll where the material is packaged on the cutting table, detection of a defect in the material on the cutting table, and detection of a defect in a previously cut piece that needs to be cut again. This triggering event can occur automatically (for example, in the case of a defect in the material spread on the cutting table that can be detected by the acquisition module of the cutting system) or manually by the operator. In both cases, as soon as such an activating event occurs, the operator is notified and the information is sent to the control station for processing. Upon receiving this information, a list of parts to be retained is automatically prepared (step S6 of the method). The parts on this list are those for which the new placement prepared in the next step S7 will not change their position. For example, parts that have already been cut and do not need to be cut again are included in this list of parts to be retained. During the next stage S7, the automatic placement module automatically prepares a new placement. This new arrangement is prepared independently of the initial arrangement prepared in step SI. However, the new arrangement takes into account the position of the parts to be retained (resulting from step S6) and calculates new positions for all or some of the other parts (called parts to be repositioned). These new positions do not take into account the positions of the parts to be repositioned in the initial arrangement. Furthermore, this new arrangement complies with the constraints imposed on the initial arrangement. The new setup is designed to minimize any loss of productivity. In particular, it is advantageously set up without interrupting the cutting of the remaining parts to be cut according to the initial setup. Later, different examples of preparing for the new placement will be described based on the different possible triggering events. Finally, the last stage S8 of the method consists of continuing the cutting according to the new placement (at the level of the cutting module of the cutting system). When the cut pieces reach the level of the unloading module of the cutting system, they are collected by the operator. It should be noted that an activating event may occur during the S8 cut-off stage according to the new placement, in which case stages S6 to S8 are repeated. With regard to Figures 4A and 4B, an example of the implementation of preparing a new placement will be described below in the case of an activating event consisting of the detection of the end of the roll on which the material spread out on the cutting table is packaged. In this example, the length of the current roll Re on which the material spread out on the cutting table is packaged is not sufficient to cut all the pieces from the initial layout (Figure 4A). Therefore, the remaining pieces must be produced on the next roll Rs. To manufacture the parts for the next roll Rs (Figure 4B), all pre-cutting steps must be updated (specifically material loading, identification of placement in the cutting zone, etc.). To update these steps normally, regardless of the completion of the current roll Re, a second cutting job will be created. This second job will have its own placement (containing all the parts to be cut from the next roll). In the case of processing the ends of the rolls, two new placements will therefore be necessary: - a first new placement to optimize the efficiency of the Px parts at the end of the current Re roll - a second new placement to optimize the efficiency of the Py parts associated with the next Rs roll With regard to Figures 5A and 5B, an example of the implementation of preparing a new placement in the case of an activating event consisting of the detection during cutting of a defect in the material spread on the cutting table will be described below. Figure 5A represents a placement of parts P in the cutting process by a cutting system as described in relation to Figure 2. During cutting, the acquisition module 6 (or the operator) detects a defect in the material spread on the cutting table at the level of a defect zone 16. This defect zone 16 is located at the placement of a part Pz to be cut. Before cutting parts that would become unusable (including part Pz), the cutting method according to the invention will directly prepare a new placement specifying that no part should be placed in this defective area 16. For this purpose, the defective area 16 is described in the automatic placement module to be excluded from the new placement. Figure 5B represents a possible outcome of a new placement prepared in this situation. Prior to preparing the new layout, a list of parts to be retained is established (i.e., the parts whose position will not be changed by the new layout). In the example in Figure 5B, these are specifically the Pe parts located at the level of cutting module 10. The new placement is prepared taking into account the position of the parts to be retained (Pe) and calculates new positions for all or part of the other parts (parts to be repositioned). Part Pz, which was previously located over the defective area 16, is specifically one of these parts to be repositioned. ινΐΛ / a / zuzz / uio ior The new layout is also designed to optimize material usage by avoiding the production of parts in the defective area. With regard to Figures 6A and 6B, an exemplary implementation of preparing a new placement in the case of an activating event consisting of the detection of a defect in a cut piece that needs to be cut again will be described below. In this example, the defect is not detected during the cutting of the parts but rather when they are unloaded by the operator at unloading module 12 of the cutting system. In Figure 6A, part Pv, which has defect 18, was identified by the operator during unloading. In such a situation, the known solution was to re-cut this defective piece, preparing an additional placement that contained only this piece, cutting this additional placement at the end of the current placement (with the consequent significant material losses). Conversely, as depicted in Figure 6B, the method according to the invention provides for establishing a list of parts to be retained, and then establishing a new placement that includes in particular part P'v to be cut again. The new layout is designed to optimize material usage, taking into account the position of the parts to be retained, and calculates new positions for all or part of the other parts (parts to be repositioned). The defective part P'v, which must be recut, is a specific part of one of these parts to be repositioned. Since the defective part is detected as defective during parts unloading, the initial Qi placement may be completely cut off after this defective part is detected. In this particular case illustrated by figures 7A and 7B, if the current placement Qc (which follows the initial placement Qi) is updated on the same material, the defective part P'v can then be integrated into the current placement Qc. In other words, the new arrangement prepared according to the invention comprises not only the defective part P'v, but also all the parts belonging to the current arrangement Qc. With regard to Figures 8A to 8C, the way in which the lists of parts to be kept (corresponding to step S6 of the method according to the invention) and parts to be repositioned during the preparation of the new placement will now be described (step S7 of the method according to the invention). The parts that will remain are those whose position will not be changed in the new arrangement. The parts to be repositioned are those whose position will be automatically recalculated for the new arrangement. Figure 8A represents an example of initial placement in the cutting process with the different modules of the cutting system placed from top to bottom in the direction of advance F of the material: supply module 4, acquisition module 6, cutting module 10 and discharge module 12. Among all the pieces of the initial placement, a distinction is made between the patterned pieces that have already been cut and the dotted piece that is a piece in the cutting process. In this example, the triggering event Evt consists of the detection of the end of the current roll Re on which the material spread out on the cutting table is packaged. Figure 8B illustrates the different categories to which the pieces of the initial placement are assigned as soon as the triggering event Evt (end of roll) is detected, namely: 1 / Pieces to be maintained (pieces with markings): These are pieces that are already cut or in the process of being cut. Therefore, it is necessary to maintain these pieces in their initial position and, therefore, place them in the group of pieces to be maintained. 2 / Parts to be repositioned (empty parts): These are parts that cannot maintain their initial position because they cannot be cut correctly (in the example, these are all the parts that are not on the current roll Re on the cutting table or those that are on the end of the current roll Re). Therefore, it is necessary to reposition these parts and, consequently, place them in the group of parts to be repositioned. 3 / Pieces to be arbitrated (pieces with dotted line): the other pieces of the placement. Then it is necessary to categorize each of the pieces to be arbitrated into one of the two groups (pieces to keep or pieces to reposition). The choice of categorization for these pieces to be arbitrated must take into account the fact that, to promote efficiency, all of these pieces should be considered as being to be repositioned (the greater the number of pieces to be repositioned, the greater the number of possible combinations the placement algorithm will have, allowing it to achieve greater efficiency). But it is also necessary to keep in mind that, in order to continue production, and therefore to continue cutting, all pieces must be considered to be held (the greater the number of pieces to be held, the greater the probability of receiving the result of the placement before the machine stops cutting). To this end, advantageously, the invention provides the ability to determine the number of pieces belonging to the group of pieces to be retained according to an assessment of their cutting time and the time allocated to calculating the new placement. Indeed, by evaluating the cutting time for each piece, it's possible to estimate the remaining cutting time, which is the sum of the cutting times for all the pieces being maintained. If no pieces are present in the group to be maintained, or if they have all already been cut, the remaining cutting time is zero. In this case, the cutting process will stop the timing for the new placement. The preparation time for the new placement can be limited to a time set by the software. Thus, it is possible to impose a maximum calculation time on the automatic placement module and maintain a number of pieces whose cutting time corresponds to this maximum calculation time (in addition to a possible fixed surcharge that serves as a margin). This parts search is advantageously updated by prioritizing the parts closest to unloading module 12. This arbitrary choice allows the process to remain fluid by suggesting the parts to be unloaded to the operator. The result obtained is illustrated in Figure 8C in which the pieces to be arbitrated in Figure 8B have been categorized into one of two groups (pieces to keep: pieces with stripes; and pieces to reposition: empty pieces). It should be noted that the choice of categorization of these pieces to be arbitrated (in one of the two groups: pieces to be kept or pieces to be repositioned) may also depend on the fact that some pieces to be arbitrated have a placement restriction (case of a material to be cut that consists of a printed fabric) or a proximity restriction. In particular, when it comes to placement on a printed material, the limitations of the connections between the pieces come into play, and the categorization of the pieces to be arbitrated must take this into account. In fact, when there is a connection constraint between two parts, the concept of a master part and a child part arises. The master part provides positioning instructions to the child part so that it can be positioned correctly. Therefore, a child part cannot be placed if its master part has not been placed. This explains why a child part cannot be assigned to the group to be maintained if, conversely, its master part has been placed in the group to be repositioned. It is also necessary to consider the possibility that a child piece can itself be the master piece of another piece, just as a master piece can itself be the child piece of another piece. In this context, as soon as a master piece is assigned to the group to be repositioned, all of its child pieces are also assigned. If the master piece is assigned to the group to be maintained, all its secondary pieces can be placed in the group to be repositioned, taking into account their restriction imposed by the master piece. Regarding parts with proximity restrictions, a distinction is made between: 1 / Proximity / alignment constraint (quality constraint) that forces two pieces to maintain their relative positioning with each other, to ensure, for example, perfect thread continuity. These pieces form a fixed and indivisible block. This means that these pieces will either all be assigned to the group to be kept on the current roll, or they will all be assigned to the group to be repositioned and placed on the next roll, maintaining their relative position. 2 / Proximity restriction that limits the distance between linked pieces and their master: - either to guarantee the cutting of the pieces (proximity -X): this proximity -X is the distance that limits the distance of the master piece from its daughter, when the latter is placed in front of its master, so that both are in the same cutting window; - or to guarantee product quality (color stability in the roll, whose coating deteriorates along its length), the distance between the master piece and the linked pieces can be limited on all other axes: +X proximity to limit the distance between the master piece and the linked piece when the latter is placed after the master piece, +Y / -Y proximity to limit the distance between the linked piece and the master piece when the former is placed above - respectively below - the master piece). In this case, these pieces also form a fixed and indivisible block, so they will all be assigned to the group to be kept on the current roll, or all assigned to the group to be repositioned and placed on the next roll, maintaining their relative position. However, this restriction is not always met. This is particularly the case when one piece in the group has already been cut and must be kept, while another piece must be repositioned. Once the assignment to one of the two groups of the pieces to be arbitrated has been updated, production can be resumed (if it has been interrupted) or continue (if it has not been interrupted) in parallel with the preparation of the new automatic placement (step S7 of the method). In addition to the placement or proximity restrictions associated with each piece or imposed by the material, it is necessary to specify new information to establish the new placement. As previously discussed, the setup time for the new placement is limited by the remaining cutting time. Furthermore, processing can be interrupted if a certain efficiency level is reached. Therefore, the system can parameterize the preparation of the new automatic placement by giving a maximum calculation time and a target efficiency. Furthermore, the dimensions of the area for the new installation will depend on the material on which the new installation will be carried out. These dimensions depend on the context of the new installation, namely: 1 / The width can be given by the bandwidth measured on the machine, or taken from the characteristics of the material; a limitation can be given by the bandwidth measured on the machine, or taken from the characteristics of the material. 2 / A maximum placement limit (Xmax) can be imposed. If the end of the roll is known, it is defined by the roll end detection. If the end of the roll is unknown, this limit is infinite. 3 / A minimum placement limit (Xmin) can be specified to prevent placing parts in an area that would be inaccessible to the cutting module as the cut continues. As the cut progresses, the cutting module and the automatic placement module share the minimum position that can be unloaded from the cutting area. This position will be the usable value for the placement module. This minimum Xmin must take into account the space left accessible by the parts to be repositioned and the areas inaccessible to the cutting module or the held parts. For each part to be held, Pc(i), the maximum Max(i) is calculated, and for each part to be repositioned, Pr(j), the minimum Min(j) is calculated. The limitation Xmin will be equal to the greater of the Max(i) values ​​less than the sum of the Min(j) values. The cutting module must ensure that this placement position does not deplete the cutting area. During the automatic setup of the new placement, production can be resumed, allowing the cutting and unloading of the held parts to continue. However, to avoid moving material needed for part placement to an area inaccessible to the cutting module, the conveyor advances must be limited to the same value as the authorized part placement position (Xmin). Thus limited, production can resume its course: the repositioning of the parts will always be limited to an area accessible by the cutting module regardless of the advances of the conveyor. Figures 9A to 9C represent the different stages of an exemplary implementation of the new placement features according to the method of the invention. Figure 9A thus represents the possible area Z1 on the surface of the cutting table for the new placement, as well as the parts of the initial placement belonging to the group to be maintained and those belonging to the group to be repositioned. Figure 9B represents the information sent to the automatic placement module for the preparation of the new placement, namely: the placement limitations Xmax and Xmin that define the limits for the preparation of the new placement, the parts to be maintained that are placed, and a list of parts to be repositioned that are no longer placed. Finally, Figure 9C shows the placement of the new layout prepared for the repositioned parts. Furthermore, as described above, the case of placements on stamped material adds the limitations of the connections between the pieces. Additionally, when choosing the categorization of the pieces to be retained or repositioned, a child piece can be separated from its master piece. Moreover, even if both the child and master pieces belong to the group to be repositioned, there is no guarantee that the two pieces can be placed in the same position. If the master part is placed in the first new position and the daughter part in the second new position, a processing method quite similar to that established in patent application FR 20 02947 filed on March 26, 2020, by the Applicant is established. This involves transforming the connection point of the daughter part into a stamped point to ensure that this part can be processed independently of its master part. Unlike the case in patent application FR 20 02947, the final position of the master piece may not be known at the time of this transformation. To obtain an acceptable result, the current position of the piece will be extrapolated based on the length of the current stage. A frame (current theoretical frame) will be constructed from the theoretical frame, but using the stage length currently measured at the time of cutting (the average value of the last two lines) as the step length. If a part is linked to two master parts (one along each axis) at two different attachment points, the pattern point created will be calculated from the intersection (projection on each axis) of the attachment points from the extrapolated position of the master parts. Otherwise, when a child part is placed in the first new placement and the master part in the second new placement, the extrapolated position of the master part cannot be determined (particularly because the current pitch of the new roll is unknown). The connection point transformation cannot be applied to the pattern point. Therefore, this part cannot be processed. To avoid this scenario, a parameter in the automatic placement module ensures that a part will only be positioned in a new placement if all its master parts are already positioned there. Now we will describe how productivity can be improved. The objective of the new layout is to address a problem that requires modifying the initial layout with the least possible impact on productivity. To this end, the calculation time for the new layout will be masked by cutting the parts that have remained in their initial position. This therefore implies that the time allocated for updating the new layout is fixed. In some cases, the calculation time will be short because the problem to be solved involves high reactivity. This is the case, for example, in defect detection when the area of ​​unusable material is known shortly before the component parts are cut. Thus, only a few parts can be assigned to the group to be maintained, and therefore the placement time will be short. If the triggering event occurs far from the end of the initial placement, many pieces will need to be replaced. Given the placement time constraint explained earlier, the placement result may not be satisfactory. In this case, a second optimization phase can be applied. It will work similarly to the first (keeping the pieces to be cut to hide the calculation time and replacing the others). This time, a larger number of pieces will be kept so that the automatic placement module can prepare a second placement, albeit with a longer calculation time. The pieces from this second (better than the first) result can be integrated into the placement in progress without interruption.

Claims

CLAIMS 1. A method for automatically cutting parts from a flexible material packaged in roll form, comprising the successive steps of: a) preparing an initial layout (S1) for a list of parts to be cut from the flexible material; b) spreading (S2) at least one layer of flexible material onto a cutting table; c) initiating (S5) the automatic cutting of parts from the material spread on the cutting table according to the initial layout; d) during the cutting of the initial layout, upon receiving an activating event (Evt) for which the layout of at least one of the parts is no longer suitable for the cutting environment or for which the list of parts in the initial layout needs to be modified, preparing a list of parts to be retained (S6);(e) automatically prepare a new arrangement (S7) taking into account the position of the parts to be maintained and calculate new positions for all or part of the other parts - called parts to be repositioned - without taking into account their positions in the initial arrangement.; 2. The method according to claim 1, wherein step e) is followed by step f) of automatic cutting (S8) of the parts in the material spread on the cutting table according to the new placement.

3. The method according to any of claims 1 and 2, wherein the new arrangement prepared in step e) comprises all or part of the pieces of the initial arrangement that are yet to be cut out.

4. The method according to claim 3, wherein the new arrangement prepared in step e) further comprises one or more parts for which the arrangement is no longer adapted to the cutting environment.

5. The method according to any of claims 3 and 4, wherein step d) comprises determining the number of retained pieces that are yet to be cut according to an assessment of their cutting time and the time allocated to calculating the new placement.

6. The method according to claim 5, wherein the time spent calculating the new placement is less than the evaluation of the cutting time of the parts to be kept that are still to be cut.

7. The method according to any of claims 3 to 6, wherein the selection of the pieces for the new arrangement from among all the pieces of the initial arrangement that are yet to be cut is updated in compliance with any arrangement constraints of said pieces.

8. The method according to any one of claims 1 to 7, wherein the triggering event is selected from: a detection of the end of the roll in which the material spread on the cutting table is packaged, a detection of a defect in the material spread on the cutting table, and the detection of a defect in a cut piece that needs to be cut again.

9. The method according to claim 8, wherein, when the triggering event consists of detecting the end of the roll on which the material spread on the cutting table is packaged, step e) comprises establishing a first placement of pieces on the end of the roll, and a second placement of the remaining pieces on another roll of material.

10. The method according to claim 8, wherein, when the triggering event consists of the detection of a defect in the material spread on the cutting table, step e) comprises excluding the area of ​​the spread material on which the defect is present in order to establish the new placement.

11. The method according to claim 8, wherein, when the triggering event consists of the detection of a defect in a cut piece that needs to be cut again, step e) comprises adding the defective piece to the new placement.

12. The method according to any of claims 1 to 11, wherein the new placement of step e) is arranged to minimize any loss of productivity.

13. The method according to claim 12, wherein step e) is carried out without interrupting the cutting of the parts to be held, which still need to be trimmed according to the initial placement.

14. The method according to any of claims 1 to 13, wherein step e) of preparing the new placement is carried out iteratively in order to obtain the highest possible efficiency index.

15. The method according to any of claims 1 to 14, wherein step c) comprises a prior step of modifying the initial placement to generate an actual placement of the pieces on the spread material that takes into account the actual characteristics of the material.

16. A system for automatically cutting parts from a flexible material packaged in roll form, comprising: - means for preparing an initial arrangement of a list of parts to be cut from the flexible material; - a cutting table on which at least one layer of flexible material can be spread; - means for automatically cutting the parts from the material spread on the cutting table according to the initial arrangement; - means for receiving, during the cutting of the initial arrangement, an activating event whereby the arrangement of at least one of the parts is no longer suitable for the cutting environment or whereby the list of parts in the initial arrangement needs to be modified;and - means for automatically preparing a list of parts to be maintained and a new placement taking into account the position of the parts to be maintained and calculating new positions for all or part of the other parts - called parts to be repositioned - without taking into account their positions in the initial placement.;

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