Packaging box plate laser cutting self-adaptive positioning method and system

Abstract

The invention relates to the technical field of plate laser cutting positioning, and discloses a packaging box plate laser cutting self-adaptive positioning method and system.The method comprises the steps that a drawing file of a plate is obtained, a cutting path of the plate is obtained according to the drawing file of the plate, height measurement scanning is conducted on the plate, and a height distribution map is established according to the height measurement scanning result; generating a macroscopic focusing reference according to the height distribution diagram; historical data of the plate is obtained, a nonlinear segmented fitting model of a common warping form is established according to the historical data of the plate, the height distribution map and the nonlinear segmented fitting model are compared and superposed, and a segmented focusing curve is generated; and adjusting the z-axis of the cutting path according to the segmented focusing curve to generate a formal cutting path, cutting the plate according to the formal cutting path, collecting the height of the plate in real time in the cutting process, and finely adjusting the formal cutting path. The method disclosed by the invention has targeted advantages on easily-deformed materials, the phenomenon of incomplete cutting or overburning is effectively reduced, and the qualified rate of finished products is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of laser cutting positioning for plates, and specifically to an adaptive positioning method and system for laser cutting of packaging box plates. Background Art

[0002] Packaging boxes are widely used in fields such as logistics, warehousing, and e-commerce. Their main structures are usually composed of low-rigidity materials such as corrugated cardboard and composite plates. In order to meet diverse packaging requirements, laser cutting technology is often used on existing production lines to cut and slot plates. Laser cutting has advantages such as high processing accuracy, strong flexibility, and neat cutting edges, and is particularly suitable for small and medium batch, multi-model packaging customization scenarios.

[0003] However, due to the soft material and uneven thickness of the plates for packaging boxes, deformation or warping is likely to occur during placement, resulting in problems such as focus shift, incomplete cutting, burning of the edges, or decreased accuracy during laser cutting. In the prior art, some systems focus by fixing the height or single-point measurement, and cannot accurately respond to the height differences in different regions of large-sized plates, resulting in poor stability of cutting quality. At the same time, although the real-time full-process height measurement and focusing system has high accuracy, the equipment complexity and cost are significantly increased, and the control algorithm delay is likely to cause misadjustment or vibration.

[0004] Therefore, there is an urgent need for an adaptive positioning method for laser cutting that takes into account both cutting accuracy and system cost and can adapt to the warping characteristics of the plates, so as to improve the intelligence and stability of the processing of packaging box plates and ensure the consistency and efficiency of the finished product quality. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed.

[0006] Therefore, the technical problem solved by the present invention is: the problem that by focusing in the way of fixing the height or single-point measurement, it is impossible to accurately respond to the height differences in different regions of large-sized plates, and the stability of cutting quality is poor.

[0007] To solve the above technical problem, the present invention provides the following technical solution: an adaptive positioning method for laser cutting of packaging box plates, including: obtaining the drawing file of the plate, obtaining the cutting path of the plate according to the drawing file of the plate, performing height measurement scanning on the plate, establishing a height distribution map according to the result of the height measurement scanning, and generating a macro-focusing reference according to the height distribution map;

[0008] Obtaining the historical data of the plate, establishing a non-linear piecewise fitting model of common warping forms according to the historical data of the plate, comparing and superimposing the height distribution map and the non-linear piecewise fitting model, and generating a piecewise focusing curve;

[0009] Adjust the z-axis of the cutting path according to the segmented focusing curve to generate the formal cutting path, and cut the sheet according to the formal cutting path. During the cutting process, the height of the sheet is collected in real time and the formal cutting path is finely adjusted.

[0010] As a preferred solution of the laser cutting adaptive positioning method for packaging box sheets described in the present invention, wherein: the obtaining of the drawing file of the sheet includes that the operator manually imports it, or the control system automatically issues the drawing file to be cut. The drawing file contains sheet size data, the best focusing position, the unfolded contour of the packaging box, the folding line and the positioning point information.

[0011] As a preferred solution of the laser cutting adaptive positioning method for packaging box sheets described in the present invention, wherein: the establishing of the height distribution map according to the result of height measurement scanning includes that before the cutting task starts, the system automatically generates a scanning path according to the sheet size data, and establishes grid points in the XY plane of the sheet with a step of distance Q;

[0012] Starting from the lower left corner (X0, Y0) of the sheet, trigger height measurement at the current point every time Q is moved until the upper right corner (X max , Y max ) of the sheet to complete the entire grid;

[0013] During the height measurement process, the control system records the (X i , Y i ) of the current grid point and the height H i output by the sensor to form a height sampling data set;

[0014] Save the height sampling data set in the form of a 2D array, visualize the height sampling data set through a graphics engine to obtain a height distribution map, and construct a height function H(X, Y) through multivariate polynomial interpolation.

[0015] As a preferred solution of the laser cutting adaptive positioning method for packaging box sheets described in the present invention, wherein: the generating of the macro focusing reference according to the height distribution map includes generating a preliminary focusing reference for any coordinate point (X i , Y i ) according to the best focusing position and the height function H(X, Y):

[0016] Z b (X i , Y i ) = H(X i , Y i ) - d f

[0017] Wherein, Z b (X i , Y i) represents the preliminary focusing reference for the coordinate point (X i , Y i ); H(X i , Y i ) represents the height of the coordinate point (X i , Y i ); d f represents the optimal focusing position;

[0018] Segment the cutting path for sampling, divide the path into segments at fixed intervals of length L, and obtain the average focusing reference for each path segment:

[0019]

[0020] Among them, Z s represents the average focusing reference; Z b (X L0 , Y L0 ) represents the preliminary focusing reference for the starting point of the path segment; Z b (X L1 , Y L1 ) represents the preliminary focusing reference for the ending point of the path segment;

[0021] Use the average focusing reference as the macroscopic focusing reference for each path segment, and avoid violent vibration of the Z-axis through smooth transition in the middle.

[0022] As a preferred solution of the laser cutting adaptive positioning method for packaging box plates described in the present invention, wherein: the common warping forms include warping around the perimeter, bulging in the middle, local collapse, and distortion, measure the height of each type of common warping form and fit to establish a height equation;

[0023] Select the key points of each type of common warping form, the key points are the coordinate points of the area with the most prominent warping characteristics in the corresponding common warping form, and each non-linear piecewise fitting model includes a height equation, key points, and a textual description of the warping form.

[0024] As a preferred solution of the laser cutting adaptive positioning method for packaging box plates described in the present invention, wherein: the segmented focusing curve includes, after aligning the measured height function H(X, Y) with the non-linear piecewise fitting model in the same coordinate system, calculating the global mean square error:

[0025]

[0026] Among them, E g represents the global mean square error; N represents the total number of comparison points; G(X i , Y i ) represents the height of the coordinate point (X i , Y i ) in the non-linear piecewise fitting model;

[0027] Select the non - linear piece - wise fitting model that minimizes E g Retrieve the key points of the non - linear piece - wise fitting model and map them to the measured height function H(X, Y). For each key point, the increment is expressed as:

[0028]

[0029] where, Δ m represents the increment of key point m; represents the preliminary focusing reference of key point m in the non - linear piece - wise fitting model; Z s (X m , Y m ) represents the average focusing reference of key point m on the measured sheet;

[0030] Form an increment correction function through scatter interpolation to correct the average focusing reference of the path segment, and obtain the final focusing reference Z f . Integrate the final focusing references of all path segments to obtain a segmented focusing curve.

[0031] As a preferred solution of the laser cutting adaptive positioning method for packaging box sheets according to the present invention, where: the fine - tuning of the formal cutting path includes, during formal cutting, for any point on the formal cutting path, calculate the focusing error according to the final focusing reference Z f and the height of the sheet collected in real - time, and fine - tune the formal cutting path according to the focusing error.

[0032] A laser cutting adaptive positioning system for packaging box sheets adopting any of the methods of the present invention, where: a ranging module, which obtains the drawing file of the sheet, obtains the cutting path of the sheet according to the drawing file of the sheet, performs height measurement scanning on the sheet, establishes a height distribution map according to the result of the height measurement scanning, and generates a macroscopic focusing reference according to the height distribution map;

[0033] A focusing module, which obtains the historical data of the sheet, establishes a non - linear piece - wise fitting model of common warping forms according to the historical data of the sheet, compares and superimposes the height distribution map and the non - linear piece - wise fitting model, and generates a segmented focusing curve;

[0034] A cutting module, which adjusts the z - axis of the cutting path according to the segmented focusing curve to generate a formal cutting path, cuts the sheet according to the formal cutting path, and in the process of cutting, collects the height of the sheet in real - time and fine - tunes the formal cutting path.

[0035] A computer device, including: a memory and a processor; the memory stores a computer program, including: when the processor executes the computer program, it implements the steps of any of the methods in the present invention.

[0036] A computer-readable storage medium storing a computer program thereon, comprising: steps of implementing the method according to any one of the present inventions when the computer program is executed by a processor.

[0037] Advantages of the present invention: Before formal cutting, the present invention uses pre-scanning technology to obtain the macroscopic height distribution of the sheet material, and combines a non-linear piecewise fitting model of the common warping forms of the packaging box sheet material to generate an accurate Z-axis focus reference. During the cutting process, combined with real-time distance detection and fine-tuning control, efficient and flexible compensation for local deformation is carried out. Compared with the traditional method of setting once or measuring at high speed throughout the process, it not only greatly reduces the hardware complexity and system cost, but also significantly improves the cutting quality and efficiency. When the sheet material is warped on a large scale, the present invention can first make macroscopic height compensation, so that the laser focus maintains the best cutting conditions in most areas, and only makes small corrections when obvious deviations are found, avoiding vibrations and delays caused by frequent focusing. It has targeted advantages for easily deformable materials such as corrugated cardboard, effectively reducing the phenomena of incomplete cutting or overburning, improving the qualified rate of finished products, and can significantly shorten the processing cycle and save energy consumption. It has outstanding application value in both flexible packaging customization and large-scale industrial production. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 It is the overall flowchart of a laser cutting adaptive positioning method for a packaging box sheet material provided by an embodiment of the present invention. Detailed Embodiments

[0040] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following will make a detailed description of the specific embodiments of the present invention in conjunction with the drawings of the specification. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0041] Example 1, referring to Figure 1 , which is an embodiment of the present invention, provides a laser cutting adaptive positioning method for a packaging box sheet material, including:

[0042] S1: Obtain the drawing file of the sheet material, acquire the cutting path of the sheet material according to the drawing file of the sheet material, perform height measurement scanning on the sheet material, establish a height distribution map based on the results of the height measurement scanning, and generate a macro focus reference according to the height distribution map.

[0043] Further, before the cutting task starts, the operator manually imports the drawing files to be cut (such as.dxf,.svg,.ai, etc.) into the control software. These files usually come from packaging design software. In a large-scale packaging production workshop, the production line is usually connected to the MES (Manufacturing Execution System) or ERP system. The system automatically issues processing tasks such as drawings, parameters, and quantities to the laser cutting machine according to the production order. The control software of the laser cutting system calls the corresponding drawing from the task management system and automatically generates the cutting path. The drawing file contains sheet material size data, the best focus position, the unfolded contour of the packing box, fold lines, and positioning point information.

[0044] Install a laser ranging sensor on the laser cutting head or an independent scanning module. The workbench is equipped with an XY movement mechanism (such as a servo motor + ball screw / linear guide rail), which can quickly move the scanning module or directly move the cutting head to a specified coordinate point in the plane for measurement.

[0045] Before the cutting task starts, the system automatically generates a scanning path according to the sheet material size data, and establishes grid points in the XY plane of the sheet material with a step of distance Q. For example, if the size of the sheet material to be processed is 1.2m × 0.9m in length and width, grid points are established in the XY plane with a step of 200mm - 300mm. The step distance can be set as a fixed value or adjusted according to the size ratio of the sheet material to be processed.

[0046] When pre-scanning to obtain the height distribution of the sheet material, the present invention tends to perform a relatively sparse grid scan on the sheet material (taking a point every 200mm or 300mm), and can encrypt the scan locally as needed. For paper or composite sheets, on the one hand, their warping often has large-scale and slow-changing deformation characteristics (unlike thin metal sheets that have sharp height changes in a small range), so the overall convex and concave trend can be captured by a large step size. On the other hand, the surface consistency and dimensional accuracy requirements of cardboard are usually not as strict as those in metal processing. Therefore, it is not necessary to make extremely dense measurements for each point, which not only reduces the scanning time but also avoids contact or vibration interference on the flexible sheet material caused by too frequent data collection.

[0047] Starting from the lower left corner (X0, Y0) of the sheet material, trigger height measurement at the current point every time moving Q until the upper right corner (X max , Y max ) of the sheet material to complete the entire grid.

[0048] During the height measurement process, the control system records the (X i , Y i) and the height H output by the sensor i , to form a height sampling data set.

[0049] It should be noted that in actual cutting operations, on the one hand, it is necessary to visually understand which area of the sheet is convex / depressed (for manual or system inspection), and on the other hand, the control software needs to be able to quickly call this distribution information for subsequent Z-axis compensation during cutting. Therefore, the system usually generates a height distribution map internally for visualization and quick inspection; at the same time, at the software algorithm level, it is converted into a height equation or interpolation function for path planning to call.

[0050] Specifically, the height sampling data set is saved in the form of a 2D array, and the height sampling data set is visualized through a graphics engine to obtain a height distribution map. The darker or brighter the color, the higher or lower the sheet is. The operator can quickly check whether there are abnormal warps in certain areas.

[0051] A height function H(X, Y) is constructed through multivariate polynomial interpolation. During subsequent cutting, as long as a certain coordinate point (X, Y) is given, the corresponding sheet height can be queried through H(X, Y), and then the Z-axis or focus compensation value can be calculated therefrom. If there are large differences in the sheet partition in practice, a segmented or grid-divided method can also be used to fit several local areas respectively, in order to improve the fitting accuracy and reduce the computational amount.

[0052] Furthermore, for a given sheet and laser processing technology, there is usually an optimal focusing position, such as 0.1 mm to 0.2 mm below the sheet surface (determined according to the material and cutting type). The optimal focusing position represents the best gap between the laser focus and the sheet surface.

[0053] Generate a macro-focusing reference according to the height distribution map. According to the optimal focusing position and the height function H(X, Y), for any coordinate point (X i , Y i ) to generate a preliminary focusing reference:

[0054] Z b (X i , Y i ) = H(X i , Y i ) - d f

[0055] Among them, Z b (X i , Y i ) represents the preliminary focusing reference of the coordinate point (X i , Y i ); H(X i , Y i ) represents the coordinate point (X i , Yi ) height; d f represents the optimal focus position.

[0056] The cutting path obtained according to the drawing file can be discretized into a series of ordered line segments or curve segments. The cutting path is sampled in segments, and each path segment is divided every fixed length L to obtain the average focusing reference for each path segment:

[0057]

[0058] where Z s represents the average focusing reference; Z b (X L0 , Y L0 ) represents the preliminary focusing reference of the starting point of the path segment; Z b (X L1 , Y L1 ) represents the preliminary focusing reference of the end point of the path segment; for curves or irregular polylines, the sampling points can be adaptively increased or decreased according to the curve length or curvature to finely describe the height change of the plate.

[0059] Segmented focusing is adopted. For each divided path segment, a Z-axis reference value, that is, the average focusing reference Z s , is used for each segment, and smooth transitions (such as trapezoidal or S-shaped interpolation) are used in the middle to avoid violent vibration of the Z axis.

[0060] It should be noted that the segmented processing is to make the Z-axis adjustment simpler and more efficient. If the plate is relatively large and the uneven places are unevenly distributed, a long cutting trajectory may cross multiple undulations.

[0061] If we regard the entire trajectory as the same height, then the focus will be too high in some places and too low in other places, and the accuracy will be affected. If we focus at every millimeter and every step, it will require very strong hardware, fast feedback, and also need to overcome problems such as jitter and delay, and both the cost and technical threshold are high. So there is a compromise: segmented or continuous focus compensation curves. It will let the cutting head use one or a smooth transition Z value in "this section of the road", and then fine-tune in the next section.

[0062] During the forming, storage, or transportation of paper-based sheets, regional bending or corner warping often occurs, which are minor errors that are not consistent across the entire sheet. By segmenting the cutting path, the software can perform interpolation correction on relatively independent warping areas, reducing the interference of "local extreme values" on global fitting. In contrast, if only a single global plane or a single polynomial is used for fitting, it works well for metal sheets that are overall flat, but for paper sheets with obvious regional differences, it is prone to distortion. "Segmentation + multi-region interpolation" precisely exploits the advantage of flexible compensation for local warping and is also suitable for the random deformation characteristics of paper sheets that may warp in different directions.

[0063] S2: Obtain the historical data of the sheet, establish a non-linear segmented fitting model for common warping patterns based on the historical data of the sheet, compare and overlay the height distribution map and the non-linear segmented fitting model, and generate a segmented focus curve.

[0064] Furthermore, select sample packaging sheets that can represent different types of warping from daily production or test batches, covering various materials (such as corrugated cardboard with different numbers of layers, composite cardboard) and various degrees of deformation. Obtain the height distribution of the sheet through pre-scanning, collect the surface height distribution of each sheet as a set of three-dimensional coordinate points, or several height maps with sufficient resolution, save the data of sheets with different material types and warping types, as well as the corresponding height distributions, as the historical data of the sheet. The data collected during actual processing can also be used as the historical data described here to continuously optimize and update the non-linear segmented fitting model.

[0065] Unify the coordinate systems of the collected three-dimensional coordinates. According to indicators such as the maximum height difference, average height of the four sides, and average height of the middle part, the samples can be roughly classified as follows:

[0066] Feature of warping at the four sides: The local Z value at the four corners or edges is relatively high;

[0067] Feature of middle bulge: The Z value in the middle is greater than that at the edge;

[0068] Feature of local collapse: Obvious pits appear in a certain area;

[0069] Feature of torsional deformation: Warping is obvious at the diagonals or specific areas.

[0070] For each common warping form, height measurement is carried out and curve fitting is performed to establish a height equation. Key points of each common warping form are selected. The key points are the coordinate points of the regions with the most prominent warping features in the corresponding common warping form. Each non - linear piece - wise fitting model includes a height equation, key points, and a textual description of the warping form. The non - linear piece - wise fitting models are stored in a fitting model database. Specifically, taking the feature of warping up at the four sides as an example, the heights of the four corners or the edge regions of the board are significantly higher than those in the middle, and the middle is relatively flat. The key points can be set as the four corners and the mid - points of the four sides. The coordinate positions of the key points are set in advance. For each new board, after normalizing the coordinate system, the key points are automatically set corresponding to the positions. Combining with the saved height equation, automatic selection and numerical reading of the key points can be achieved.

[0071] Furthermore, by comparing and superimposing the height distribution map and the non - linear piece - wise fitting model, a segmented focusing curve is generated. After aligning the measured height function H(X, Y) and the non - linear piece - wise fitting model in the same coordinate system, the global mean square error is calculated:

[0072]

[0073] where, E g represents the global mean square error; N represents the total number of comparison points; G(X i , Y i ) represents the height of the coordinate point (X i , Y i ) in the non - linear piece - wise fitting model.

[0074] Select the non - linear piece - wise fitting model that minimizes E g . Retrieve the key points of the non - linear piece - wise fitting model and map them to the measured height function H(X, Y). For each key point, the increment is expressed as:

[0075]

[0076] where, Δ m represents the increment of key point m; represents the preliminary focusing reference of key point m in the non - linear piece - wise fitting model; Z s (X m , Y m ) represents the average focusing reference of key point m on the measured board.

[0077] It should be noted that the non - linear piece - wise fitting model with the minimum E g is considered to be the most likely warping mode of the entire board. If the difference is still large, it indicates that the board does not conform to any typical form (and the non - linear piece - wise fitting model can be directly not modified). In this case, local detection is not performed, but a global form judgment is made: only the most similar one is taken.

[0078] An incremental correction function is formed through scatter point interpolation to correct the average focusing reference of the path segment, and the final focusing reference Z is obtained. f , and the final focusing references of all path segments are integrated to obtain a segmented focusing curve. Specifically, the increment Δ m at the key point m represents how much higher (or lower) it should be than Z s near the m point. For the actual deformation of the sheet, smooth correction is also required near the key points. In the area far from all key points, the correction amount gradually approaches 0, ensuring that if a certain place is far from all key points, no correction or only a very small correction is made. The final focusing reference Z f is obtained by adding the average focusing reference and the increment correction function obtained by interpolation. The scatter point interpolation includes methods such as inverse distance weighting and radial basis functions.

[0079] It should be noted that for the average focusing reference obtained through macro focusing, the height compensation or fitting effect in some areas is not perfect, resulting in a significant difference between the model and the actual situation at the key points, and the difference does not only exist at the points - it often affects or represents an area around the point. And as mentioned above, considering the characteristics of the packaging box sheet, the cost of high-precision computational focusing for the entire sheet is much greater than the benefit. Therefore, by selecting the key points at the deformation positions, forming a segmented average focusing - a non-linear segmented fitting model corresponding to common warping forms - and focusing around the key points, a large improvement in accuracy can be achieved without significantly increasing the computational amount.

[0080] S3: Adjust the z-axis of the cutting path according to the segmented focusing curve to generate a formal cutting path, and cut the sheet according to the formal cutting path. During the cutting process, the height of the sheet is collected in real time and the formal cutting path is finely adjusted.

[0081] Furthermore, based on obtaining the cutting path of the sheet according to the drawing file of the sheet, the segmented focusing curve is imported into the numerical control system to form an initial setting value for the Z-axis. If the system uses G-code, corresponding Z commands can be inserted in different path segments, or stored in the motion controller in the form of a table / curve to generate a formal cutting path.

[0082] The controller moves the cutting head in the X-Y plane according to the formal cutting path, and at the same time the laser starts to output according to the predetermined power. In the absence of a real-time correction signal, the Z-axis (or the dynamic focusing lens group) defaults to follow the height / focal length indicated by Z f . If the height change in most areas of the sheet is consistent with the previous fitting result, the laser cutting head keeps the current Z value unchanged and continuously performs cutting. In most cases, the segmented focusing curve generated by pre-scanning and the prior model before is sufficient to ensure good cutting quality.

[0083] The distance sensor (laser distance measurement, ToF or capacitive, etc.) installed near the laser head continuously obtains the actual distance between the cutting head and the plate surface. The sampling frequency can be determined according to the cutting speed, or it can be sampled again at the start / end point of each path segment.

[0084] The current Z-axis command value is Z f , the actual surface height detected by the sensor is Z actual , the current error can be written as:

[0085] e=(Z f -Z actual )-d f

[0086] Where e represents the error of the Z axis from the ideal focus. A permissible threshold is set for the error e. When e does not exceed the permissible threshold, it indicates that the current height is close enough to the segmented curve and no additional action is required. When e exceeds the permissible threshold, fine-tuning is performed.

[0087] The controller drives the Z-axis servo or dynamic focusing lens group to make fine adjustments through PID control. The adjusted Z value = the original value of the segmented curve + the fine-tuning amount. If the error is still large after re-measuring, it will continue to iterate until it returns to within the threshold. To avoid frequent vibrations, error evaluation and fine-tuning can be performed again at a specified period (such as every 50ms) or after the cutting head displacement exceeds a certain distance to balance accuracy and stability.

[0088] Set the upper / lower limit of the Z axis. If the fine-tuning amount exceeds the physical limit, an alarm will be issued or the cutting will be suspended to prevent uncontrollable movement due to sensor failure or extreme deformation. Ultimately, through the triple mechanism of "macro-benchmark + prior model correction + real-time fine-tuning", it is ensured that the plate has sufficient cutting depth and focus accuracy in different areas, improving the consistency and qualified rate of finished products.

[0089] It should be noted that the optimal segmented focusing curve Z has been generated before the formal cutting. f During the actual cutting, the real-time distance measurement is used to determine whether a slight correction is needed, and the Z axis is closed-loop controlled when the threshold is exceeded. This not only avoids the high hardware burden and jitter problems of the traditional method of full-process high-speed real-time measurement, but also ensures the ability to correct local sudden deformation, forming a high-precision, low-cost, and efficient laser cutting system.

[0090] Embodiment 2: In an exemplary embodiment, an adaptive positioning system for laser cutting of packaging box plates is also provided, including a ranging module, a focusing module and a cutting module.

[0091] Specifically, the ranging module obtains the drawing file of the board, acquires the cutting path of the board according to the drawing file of the board, performs height measurement scanning on the board, establishes a height distribution map based on the results of the height measurement scanning, and generates a macro-focusing reference based on the height distribution map.

[0092] The focusing module obtains the historical data of the board, establishes a non-linear piecewise fitting model of common warping forms according to the historical data of the board, compares and superimposes the height distribution map and the non-linear piecewise fitting model, and generates a piecewise focusing curve.

[0093] The cutting module adjusts the z-axis of the cutting path according to the piecewise focusing curve to generate a formal cutting path, cuts the board according to the formal cutting path, and real-time collects the height of the board during the cutting process and finely adjusts the formal cutting path.

[0094] This embodiment also provides a specific way to achieve control through the laser cutting adaptive positioning system for packaging box boards:

[0095] An operator or the MES system issues an order, which includes the drawing file of the board; the ranging module automatically obtains and generates a preliminary cutting path and a macro-focusing reference.

[0096] The ranging module scans the board to be cut on the workbench and outputs the height distribution and macro Z to the focusing module.

[0097] The focusing module calls the fitting model database and generates a piecewise focusing curve according to the comparison of the measured data.

[0098] The cutting module loads the formal cutting path and starts laser processing, and automatically performs small adjustments through sensors during this period.

[0099] If it is detected that the error maintains a large amplitude for a long time, a warning can also be triggered at the system level to remind the operator to check the board fixture or abnormal deformation.

[0100] After cutting is completed, the system stores the fine-tuning curve and the finished product quality information to provide new learning / reference for the fitting model database in the future.

[0101] In this way, the three modules form a complete closed loop: pre-scanning and preliminary compensation (ranging module), optimization based on experience and prior forms (focusing module), and actual cutting and dynamic fine-tuning (cutting module), which greatly improves the automation, precision and efficiency of laser processing of flexible boards (especially packaging box boards).

[0102] If the above functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs, etc., which can store program codes of various kinds.

[0103] The logic and / or steps represented in the flowchart or described in other ways herein, for example, can be considered as a predefined sequence list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch instructions from the instruction execution system, apparatus, or device and execute the instructions), or in combination with these instruction execution systems, apparatus, or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in combination with an instruction execution system, apparatus, or device.

[0104] More specific examples (nonexhaustive list) of computer-readable media include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk cartridge (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other media, then editing, interpreting, or otherwise processing it as appropriate, and then storing it in a computer memory.

[0105] It should be understood that each part of the present invention can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one of the following techniques known in the art or a combination thereof can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0106] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. An adaptive positioning method for laser cutting of packaging box boards, characterized in that Including: Obtain the drawing file of the sheet metal, obtain the cutting path of the sheet metal according to the drawing file of the sheet metal, perform height measurement scanning on the sheet metal, establish a height distribution map based on the result of the height measurement scanning, and generate a macro focus adjustment reference according to the height distribution map; Obtain the historical data of the sheet metal, establish a non-linear piecewise fitting model of common warping forms according to the historical data of the sheet metal, compare and superimpose the height distribution map and the non-linear piecewise fitting model, and generate a segmented focus curve; Adjust the z-axis of the cutting path according to the segmented focus curve to generate a formal cutting path, cut the sheet metal according to the formal cutting path, and collect the height of the sheet metal in real time during the cutting process and fine-tune the formal cutting path.

2. The laser cutting adaptive positioning method for a packing box board as described in claim 1, wherein: The obtaining of the drawing file of the sheet metal includes that the operator manually imports it, or the control system automatically issues the drawing file to be cut. The drawing file contains sheet metal size data, the best focus position, the unfolded contour of the packing box, fold lines and positioning point information.

3. A laser cutting adaptive positioning method for a packing box board as described in claim 2, characterized in that: The establishing of the height distribution map according to the result of the height measurement scanning includes that before the cutting task starts, the system automatically generates a scanning path according to the sheet metal size data, and establishes grid points in the XY plane of the sheet metal with a step of distance Q; Starting from the lower left corner (X0, Y0) of the sheet, measure the height once at the current point every time Q is moved until the upper right corner (X max , Y max ) of the sheet to complete the entire grid; During the height measurement process, the control system records the (X i , Y i ) of the current grid point and the height H i output by the sensor to form a height sampling data set; Save the height sampling data set in the form of a 2D array, visualize the height sampling data set through a graphics engine to obtain a height distribution map, and construct a height function H(X, Y) through multivariate polynomial interpolation.

4. The laser cutting adaptive positioning method for a packaging box board according to claim 3, characterized in that: The generation of the macro focusing reference according to the height distribution map includes generating a preliminary focusing reference for any coordinate point (X i , Y i ) based on the best focusing position and the height function H(X, Y): Z b (X i ,Y i ) = H(X i ,Y i ) - d f Among them, Z b (X i , Y i ) represents the preliminary focusing reference for the coordinate point (X i , Y i ); H(X i , Y i ) represents the height of the coordinate point (X i , Y i ); d f represents the best focusing position. Perform segmented sampling on the cutting path, divide the path segments every fixed length L, and obtain the average focus adjustment reference for each path segment: Among them, Z s represents the average focusing reference; Z b (X L0 , Y L0 ) represents the preliminary focusing reference of the starting point of the path segment; Z b (X L1 , Y L1 ) represents the preliminary focusing reference of the ending point of the path segment; Use the average focus adjustment reference as the macro focus adjustment reference for each path segment, and avoid violent vibration of the Z axis through smooth transition in the middle.

5. The laser cutting adaptive positioning method for a packing box board according to claim 4, characterized in that: The common warping forms include warping around the perimeter, bulging in the middle, local collapse and distortion. Measure the height of each type of common warping form and fit to establish a height equation; Select the key points of each type of common warping form. The key points are the coordinate points of the area with the most prominent warping characteristics in the corresponding common warping form. Each non-linear piecewise fitting model includes a height equation, key points and a text description of the warping form.

6. The laser cutting adaptive positioning method for a packing box board as described in claim 5, wherein: The segmented focus curve includes that after aligning the measured height function H(X, Y) and the non-linear piecewise fitting model in the same coordinate system, calculate the global mean square error: Among them, E g represents the global mean square error; N represents the total number of comparison points; G(X i , Y i ) represents the height of the coordinate point (X i , Y i ) in the non-linear piecewise fitting model; Select the one that minimizes E g For the non-linear piecewise fitting model, retrieve the key points of the non-linear piecewise fitting model and map them to the measured height function H(X, Y). For each key point, the increment is expressed as: Among them, Δ m represents the increment of the key point m; represents the preliminary focusing reference of the key point m in the non-linear piecewise fitting model; Z s (X m , Y m ) represents the average focusing reference of the key point m on the measured sheet material; Form an incremental correction function through scatter interpolation to correct the average focusing reference of the path segment and obtain the final focusing reference Z. f Integrate the final focusing references of all path segments to obtain a segmented focusing curve.

7. The laser cutting adaptive positioning method for a packing box board according to claim 6, wherein: The fine-tuning of the formal cutting path includes, during formal cutting, for any point on the formal cutting path, calculating the focusing error based on the final focusing reference Z f and the height of the plate collected in real time, and fine-tuning the formal cutting path according to the focusing error.

8. An adaptive positioning system for laser cutting of packaging box plates, which is applied to the adaptive positioning method for laser cutting of packaging box plates according to any one of claims 1 to 7, and is characterized in that, Including, A ranging module that obtains the drawing file of the sheet metal, obtains the cutting path of the sheet metal according to the drawing file of the sheet metal, performs height measurement scanning on the sheet metal, establishes a height distribution map based on the result of the height measurement scanning, and generates a macro focus adjustment reference according to the height distribution map; A focus adjustment module that obtains the historical data of the sheet metal, establishes a non-linear piecewise fitting model of common warping forms according to the historical data of the sheet metal, compares and superimposes the height distribution map and the non-linear piecewise fitting model, and generates a segmented focus curve; A cutting module that adjusts the z-axis of the cutting path according to the segmented focus curve to generate a formal cutting path, cuts the sheet metal according to the formal cutting path, and collects the height of the sheet metal in real time during the cutting process and fine-tunes the formal cutting path.

9. A computer device, comprising: A memory and a processor; the memory stores a computer program, characterized in that: when the processor executes the computer program, the steps of a laser cutting adaptive positioning method for a packaging box board as described in any one of claims 1-7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, the steps of a laser cutting adaptive positioning method for a packaging box board as described in any one of claims 1-7 are implemented.

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