Sheet metal laser cutting device and laser cutting method thereof

Abstract

The present application relates to the technical field of laser cutting, and particularly relates to a sheet metal laser cutting device and a laser cutting method thereof. The present application selects a piercing point of an outline and starts cutting at the piercing point; according to the pixel value difference of the corresponding pixel points in the sheet metal infrared image of the start and end time of the starting cutting point of the cutting crack in the local time period, the position and pixel value of the pixel points on the cutting crack, and the cutting position and the cutting crack width, the heat response position optimization degree is obtained; according to the relative size of the piercing optimization degree of the pixel points on the cutting crack of each local time period and the previous local time period of each outline, and the heat response position optimization degree of the previous local time period, the pulse demand degree is obtained, and then the actual pulse frequency of the previous local time period is adjusted, the preferred pulse frequency of each local time period is obtained, and the cutting of each outline is completed. The present application adaptively determines the preferred pulse frequency of the local time period of each outline, and improves the sheet metal laser cutting precision.

Description

Technical Field

[0001] This invention relates to the field of laser cutting technology, specifically to a sheet metal laser cutting processing device and its laser cutting processing method. Background Technology

[0002] Laser cutting uses a high-power laser to cut sheet metal. A series of mirrors and lenses guide and focus a high-energy beam onto the surface of the sheet metal to be cut. When the beam hits the surface, its energy melts and vaporizes the metal underneath. Any remaining molten metal or vapor is blown away from the cut by an airflow. Precise control of the laser beam's position relative to the sheet allows the laser to follow the desired cutting path, enabling the laser to cut sheet metal into the shapes required for production applications.

[0003] The selection of the puncture point and pulse control are crucial steps in sheet metal laser cutting. The puncture point is the starting point for contour cutting, and the pulse frequency reflects the energy state of the laser beam. Existing laser cutting methods typically set the pulse frequency to a fixed value to simplify the cutting process. However, in practical scenarios, the beam energy of a fixed pulse frequency may not be well-suited to sheet metal cutting. An excessively high pulse frequency can lead to excessive thermal response, causing deformation of the sheet metal material, while an excessively low pulse frequency can result in poor cutting efficiency. Therefore, a fixed pulse frequency is not well-suited to the requirements of sheet metal cutting, reducing the accuracy of sheet metal laser cutting. Summary of the Invention

[0004] To address the technical problem of low precision in sheet metal laser cutting due to the poor adaptability of fixed pulse frequencies to sheet metal cutting requirements, this invention aims to provide a sheet metal laser cutting processing device and a laser cutting processing method. The specific technical solution adopted is as follows:

[0005] This invention proposes a laser cutting method for sheet metal laser cutting processing equipment, the method comprising:

[0006] Extract the contour from the cut contour image;

[0007] Based on the degree of directional change of each contour point and its adjacent contour points on each contour, as well as the degree of drastic contour change within the local area of ​​each contour point, the puncture optimization degree of each contour point is obtained, and the puncture point of each contour is selected.

[0008] The sheet metal laser cutting processing device generates a cutting path based on the image, starts cutting at the puncture point, and acquires the cutting gap and sheet metal infrared images at all times during each local time period of each contour cutting process in real time; based on the pixel value difference of the corresponding pixel in the sheet metal infrared image at the start and end times of the cutting crack in the local time period, the position and pixel value of the pixel on the cutting crack, and the cutting position and cutting crack width, the thermal response priority of the local time period is obtained.

[0009] Based on the relative magnitude of the puncture preference of pixels on the cutting crack of each local time segment of each contour and the thermal response preference of the previous local time segment, the pulse demand of each local time segment is obtained; using the relative magnitude of the pulse demand of each local time segment of each contour and the previous local time segment, the actual pulse frequency of the previous local time segment is adjusted to obtain the preferred pulse frequency of each local time segment; the device uses the preferred pulse frequency in real time to complete the cutting of each contour.

[0010] Further, the step of obtaining the puncture optimization degree of each contour point of each contour and selecting the puncture point of each contour includes:

[0011] Obtain the unit tangent vector of each contour point on each contour; normalize the angle between each contour point on each contour and the unit tangent vector of the next contour point in the preset direction to obtain the vector change degree of each contour point.

[0012] Each contour is divided into contour segments, and the standard deviation of the slope of all contour points on the contour segment is calculated as the local intensity.

[0013] The puncture optimization degree is obtained based on the vector change degree of each contour point and the local intensity of the contour segment in which each contour point is located;

[0014] The contour point corresponding to the maximum value of the puncture preference among all contour points on each contour is selected as the puncture point.

[0015] Furthermore, obtaining the thermal response dominance for a local time period includes:

[0016] The reciprocal of the absolute value of the difference between the pixel values ​​of the corresponding pixels in the sheet metal infrared images at the start and end times of the cutting point of the local cutting crack is used as the initial retention degree of heat accumulation.

[0017] The thermal conductivity performance is obtained by taking the pixel value of the corresponding pixel in the sheet metal infrared image at all times of the local time period of the cutting crack, and the distance from the pixel on the cutting crack to the starting cutting point.

[0018] The initial heat accumulation retention is adjusted using the thermal conductivity performance to obtain the heat accumulation retention for a local time period;

[0019] The deformation risk level for a given time period is obtained based on the cutting location and the heat accumulation retention rate during that time period.

[0020] Obtain the cutting crack width and laser beam diameter parameters for a local time period; based on the difference between the cutting crack width and laser beam diameter parameters for a local time period, and the deformation risk degree, obtain the thermal response priority for that local time period.

[0021] Furthermore, the formula for calculating the thermal conductivity performance is as follows:

[0022]

[0023] In the formula, IA represents the thermal conductivity performance of the local time period; T represents the total number of moments within the local time period; and M represents the total number of contour points on the cutting crack in the local time period, excluding the starting cutting point. The distance from the starting point of the cutting crack on the local time segment to the remaining m-th contour point; , where is the pixel value of the m-th contour point on the cutting crack (excluding the starting cutting point) in the sheet metal infrared image at time t during a local time period.

[0024] Furthermore, the method for obtaining the cutting gap in each local time period includes:

[0025] Real-time acquisition of sheet metal analysis images and cut crack areas at every moment during the cutting process of each contour;

[0026] The current cutting crack region of the local time period is formed by the pixels in the sheet metal analysis image at the end of the local time period that do not correspond to the pixel positions in the sheet metal analysis image at the start of the local time period within the cut crack region. The skeleton line of the current cutting crack region is extracted and recorded as the cutting crack of the local time period. The pixels in the sheet metal analysis image and the sheet metal infrared image at the same time correspond one-to-one.

[0027] Furthermore, obtaining the deformation risk level for a local time period includes:

[0028] The line segment connecting the two endpoints of the cutting crack in the sheet metal analysis image at the end of the local time period is denoted as the main force line segment; the closed area formed by the cutting crack in the sheet metal analysis image at the end of the local time period and the main force line segment is denoted as the cut area of ​​the local time period.

[0029] The deformation risk level is obtained based on the area of ​​the cut region and the heat accumulation retention rate during a local time period.

[0030] Furthermore, obtaining the pulse demand degree for each local time period includes:

[0031] The average value of the puncture preference of all pixels on the cutting crack during a local time period is calculated and denoted as the comprehensive preference.

[0032] The ratio of the overall optimization degree of each local time segment of each contour to that of the previous local time segment is used as the adjustment coefficient for each local time segment;

[0033] The product of the adjustment coefficient of each local time period of each contour and the thermal response priority of the previous local time period is normalized to obtain the pulse demand degree of each local time period of each contour.

[0034] Further, obtaining the pulse frequency for each local time period includes:

[0035] Calculate the ratio of the pulse demand degree of each local time segment of each contour to that of the previous local time segment, and multiply the ratio by the actual pulse frequency of the previous local time segment as the preferred pulse frequency of each local time segment of each contour.

[0036] Furthermore, the thermal conductivity performance is negatively correlated with the thermal accumulation retention.

[0037] A sheet metal laser cutting processing apparatus includes a processor, which executes the steps of the laser cutting processing method of the sheet metal laser cutting processing apparatus as described above.

[0038] The present invention has the following beneficial effects:

[0039] Firstly, compared to existing methods that automatically select puncture points through control software, this method determines the probability of a contour point being selected as a puncture point, i.e., the puncture optimization degree, based on the complexity of the contour changes at the contour point position, and selects laser cutting puncture points with higher adaptability, thus initially improving the laser cutting accuracy.

[0040] Secondly, the pulse frequency during sheet metal cutting is related to thermal response and contour conditions. The difference in pixel values ​​of corresponding pixels in the sheet metal infrared images at the start and end times of the cutting crack indicates the heat accumulation during cutting. The final heat accumulation is determined by using the position and pixel values ​​of pixels on the cutting crack that show the heat conduction from other cutting points to the starting point. Simultaneously, considering the cutting position and crack width, the thermal response of the cutting in local time periods is comprehensively analyzed to obtain the thermal response priority. The relative magnitude of the puncture priority of the contour points of the cutting crack in each local time period compared to the previous local time period measures the change in contour complexity in each local time period. The thermal response priority of the previous local time period indicates excess heat. The pulse demand degree of each local time period is comprehensively analyzed to obtain the pulse demand degree. Based on the change in pulse demand degree of each local time period of each contour compared to the previous local time period, the pulse frequency of each local time period is adaptively controlled based on the negative feedback adjustment principle. Compared to a fixed pulse frequency, this solution combines contour features and cutting thermal response performance in the actual scene to obtain a more accurate laser cutting pulse control result, thereby gradually improving the cutting accuracy as the cutting process progresses. Attached Figure Description

[0041] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 A flowchart illustrating the steps of a laser cutting method using a sheet metal laser cutting processing apparatus, as provided in one embodiment of the present invention;

[0043] Figure 2 A flowchart illustrating a method for obtaining thermal response preference according to an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of a computer device for a sheet metal laser cutting processing apparatus provided in one embodiment of the present invention. Detailed Implementation

[0045] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a sheet metal laser cutting processing apparatus and its laser cutting processing method according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0047] This invention provides a sheet metal laser cutting processing device that integrates a CNC system and includes a cutting worktable and a data acquisition module. An industrial camera and an infrared camera are installed above the cutting worktable to sequentially acquire images of crack gaps and heat distribution in the sheet metal during the cutting process. The industrial camera and the infrared camera together constitute the data acquisition module. The CNC system is used to analyze and control the sheet metal laser cutting, and the data acquisition module is connected to the CNC system. The data acquisition module is used to acquire sheet metal analysis images and sheet metal infrared images at every moment during the cutting of each contour in real time and transmit them to the CNC system.

[0048] First, the cutting contour image required for the sheet metal is input into the CNC system. Second, before contour cutting, the computer vision algorithm integrated into the CNC system extracts the contour from the cutting contour image and analyzes the puncture points of each contour. Then, the vector file is imported into the CNC system, and the cutting order, puncture points, and real-time pulse power of each contour during cutting are set to generate standard G-code. Afterward, the CNC system parses the G-code and controls the laser head to complete the cutting, ultimately forming a sheet metal part consistent with the cutting contour image. The computer vision algorithm includes: extracting the contour using the Canny edge detection algorithm and vectorizing the contour and properties using the Douglas-Pock algorithm.

[0049] It should be noted that the cutting direction for each contour is set to clockwise. The center point of each contour in the cut contour image is obtained, and all contours are arranged in ascending order of distance from their center point to the image center point, resulting in a contour sequence. The cutting order of the contours in the cut contour image is the same as the contours in the contour sequence, arranged from front to back; that is, the innermost contour is processed first. The reason is that if the outermost contour is processed first, the sheet metal part may fall off after the outermost contour is cut; also, the offset of the outermost contour position will cause the cutting position of the inner contour to shift accordingly, affecting the cutting accuracy.

[0050] The following description, in conjunction with the accompanying drawings, details the specific scheme of the sheet metal laser cutting processing device and its laser cutting processing method provided by the present invention.

[0051] Example 1:

[0052] This invention proposes a laser cutting method for sheet metal laser cutting processing equipment. Please refer to [link / reference]. Figure 1 The diagram illustrates a flowchart of a laser cutting method for a sheet metal laser cutting processing apparatus according to an embodiment of the present invention. The method includes:

[0053] Step S1: Obtain the contour in the cut contour image.

[0054] The cutting contour image required by the graphic is acquired in the CNC device, and the cutting contour image is converted into discrete graphic units that can be recognized by the data system. Specifically, the closed contour with a single pixel width in the cutting contour image is extracted by contour extraction algorithm such as Canny edge detection algorithm, so as to realize the accurate decomposition of the cutting task and provide basic data for subsequent generation of cutting path.

[0055] Step S2: Based on the degree of directional change of each contour point and its adjacent contour points on each contour, as well as the degree of drastic contour change within the local area of ​​each contour point, obtain the puncture optimization degree of each contour point, and select the puncture point of each contour.

[0056] The puncture point is the starting point of laser cutting. During puncture, the laser continuously irradiates the puncture point until it penetrates the material. Because the laser acts from top to bottom, the upper surface receives energy throughout the entire process from the start of irradiation to complete penetration, while the lower surface is only irradiated for a brief moment during penetration. This results in slightly lower processing accuracy at the puncture point compared to other locations. Therefore, puncture points should be avoided in areas with complex contour variations. The degree of directional change between each contour point and its adjacent contour points represents the intensity of contour variation at the contour point location over a short period. The intensity of contour variation within a local area of ​​each contour point represents the intensity of contour variation within a local area over a short period. The greater the intensity of contour variation, the more complex the contour variation at the contour point location, and the less likely it is to be selected as a puncture point. This yields the puncture preference of the contour point; and the puncture point for each contour is selected based on the puncture preference.

[0057] Step S3: The sheet metal laser cutting processing device generates a cutting path based on the image, starts cutting at the puncture point, and acquires the cutting gap and sheet metal infrared images at all times during each local time period of each contour cutting process in real time; based on the pixel value difference of the corresponding pixel in the sheet metal infrared image at the start and end times of the cutting crack in the local time period, the position and pixel value of the pixel on the cutting crack, and the cutting position and cutting crack width, the thermal response priority of the local time period is obtained.

[0058] The laser head of the sheet metal laser cutting processing device cuts the sheet metal surface sequentially along the cutting path of the contour in the cutting contour image. The cutting path is generated with the puncture point as the starting and ending point, and the path direction is clockwise along the contour. During the cutting process of each contour, the sheet metal analysis image and sheet metal infrared image are acquired in real time at each moment through an industrial camera and an infrared camera. The time period corresponding to each contour cutting process is divided into multiple local time periods. The sheet metal analysis image refers to the crack boundary box area detected and output in real time by the YOLOv7 model based on the sheet metal RGB image acquired by the industrial camera. The sheet metal infrared image refers to the area formed by the corresponding pixels of the pixels in the sheet metal analysis image in the infrared image acquired by the infrared camera. It is ensured that only the crack area cut in real time exists in the sheet metal analysis image and the sheet metal infrared image, and the size of the analysis image is the same at all moments within the same local time period.

[0059] In this embodiment of the invention, the method for obtaining the cutting crack in a local time period is as follows: The crack region in the sheet metal analysis image is identified using the YOLOv7 model and recorded as the cut crack region; the current cutting crack region in the local time period is formed by the pixels in the cut crack region of the sheet metal analysis image at the end of the local time period that do not correspond to the pixel positions in the cut crack region of the sheet metal analysis image at the beginning of the local time period; the skeleton line of the current cutting crack region is extracted and recorded as the cutting crack in the local time period; the pixels in the sheet metal analysis image and the sheet metal infrared image at the same time correspond one-to-one. The starting cutting point of the cutting crack refers to the first pixel when traversing the cutting crack in a clockwise direction. It should be noted that the cutting contour image is usually generated as a vector contour with a single pixel width through the contour extraction algorithm, but in actual physical cutting, the laser beam will form a cutting area with a limited width on the sheet metal. The skeleton line is extracted through morphological thinning operations.

[0060] During laser cutting, the pulse frequency reflects the energy expressed by the laser beam. If the pulse frequency is too high, it will cause excessive heat accumulation at the cutting gap, which may lead to an increase in the cutting gap. If the pulse frequency is too low, it will affect the cutting efficiency. Therefore, it is necessary to analyze the thermal response when determining the pulse frequency.

[0061] When cutting a single contour, a higher pulse frequency introduces more heat into the cutting gap. If heat exceeding the melting resistance point of the sheet metal remains in the cutting gap for too long, it may cause thermal deformation at the edge of the cutting gap, requiring an assessment of heat accumulation during cutting. The starting point of the cutting crack in a localized period has the highest heat at the beginning, which decreases continuously during subsequent cuts, reaching its lowest point at the end. Therefore, the initial heat accumulation during localized cutting is represented by the pixel value difference of the corresponding pixels in the sheet metal infrared images at the two start and end times of the cutting crack's starting point. However, other contour points are cut later than the starting point. Under natural heat dissipation at the starting point, these other contour points have higher temperatures than the starting point, which can conduct heat to the starting point, leading to a higher initial heat accumulation. Therefore, it is necessary to correct the heat accumulation by utilizing the heat conduction behavior of other contour points on the starting point. The position and pixel value of the cutting crack pixels represent the heat conduction behavior of other contour points on the starting point, which is used to correct the initial heat accumulation, yielding the final heat accumulation.

[0062] During the cutting of a single contour, the cut portion tends to fall downwards due to gravity, and the cutting position at a local time affects the main stress location of the contour. If the heat generated by the pulse frequency during the cutting process is high, that is, the more severe the final heat accumulation, the higher the risk of thermal deformation at the main stress location. Combined with the width of the cutting crack, which reflects the heat conduction along the cutting path, the thermal response of the cutting at a local time is comprehensively analyzed to obtain the thermal response dominance.

[0063] In one implementation of this invention, the duration of the local time period is set to 1 second, and the image acquisition frequency of both the industrial camera and the infrared camera is set to 10 Hz. The camera's image acquisition frequency must be greater than 1 Hz to ensure multiple images are captured within 1 second, thereby improving the accuracy of thermal response dominance analysis.

[0064] It should be noted that since the cutting crack is on the sheet metal analysis image, and the pixels in the sheet metal analysis image and the sheet metal infrared image at the same time correspond one-to-one, the pixel coordinates of each pixel on the cutting crack are the same as the pixel coordinates of its corresponding pixel in the sheet metal infrared image.

[0065] Step S4: Based on the relative magnitude of the puncture preference of pixels on the cutting crack of each local time segment of each contour and the thermal response preference of the previous local time segment, obtain the pulse demand of each local time segment; using the relative magnitude of the pulse demand of each local time segment of each contour and the previous local time segment, adjust the actual pulse frequency of the previous local time segment to obtain the preferred pulse frequency of each local time segment; the device uses the preferred pulse frequency in real time to complete the cutting of each contour.

[0066] The pulse frequency requirement during sheet metal cutting is related not only to thermal response but also to the contour. A relatively lower pulse frequency should be applied to contours with higher complexity to reduce thermal interference and thus improve cutting accuracy. The penetration preference of the contour points of the cutting crack in a local time period reflects the overall complexity of the cutting crack contour. By comparing the penetration preference of the contour points of the cutting crack in each local time period with that of the previous local time period, the change in contour complexity in each local time period is measured, thereby determining the pulse frequency. Simultaneously, the lower the thermal response preference of the previous local time period, the stronger the excess heat in that period. To prevent heat accumulation across time periods, the pulse frequency of each local time period needs to be reduced. Therefore, by combining these two factors, the pulse requirement for each local time period is determined, resulting in the pulse requirement degree. Then, based on the change in pulse requirement degree of each local time period of each contour with that of the previous local time period, the pulse frequency of each local time period is adaptively controlled based on the negative feedback adjustment principle, thereby gradually improving the cutting accuracy as the cutting process progresses.

[0067] The specific pulse frequency control method is as follows: Based on the thermal response priority of the (i-1)th local time period of each contour, the pulse demand of the ith local time period is determined, and then the preferred pulse frequency of the ith local time period is determined. Here, the (i-1)th local time period is historical data, and the ith local time period is current data. The CNC system determines the preferred pulse frequency of the ith local time period at the end of the (i-1)th local time period, which is also the beginning of the ith local time period, and uses the preferred pulse frequency of the ith local time period to complete the crack cutting. The value of i ranges from a constant 3 to the total number of local time periods for each contour. When analyzing the preferred pulse frequency of the (i+1)th local time period, the actual pulse frequency of the ith local time period is its preferred pulse frequency.

[0068] It should be noted that the pulse frequency for the first two local time periods of each contour is set to 100 kHz.

[0069] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the puncture point includes: obtaining the unit tangent vector of each contour point on each contour; normalizing the angle between each contour point on each contour and the unit tangent vector of the next contour point in a preset direction to obtain the vector change degree of each contour point; dividing each contour into contour segments, calculating the standard deviation of the slope of all contour points on the contour segment as the local severity; obtaining the puncture preference degree based on the vector change degree of each contour point and the local severity of the contour segment in which each contour point is located; and selecting the contour point corresponding to the maximum value of the puncture preference degree of all contour points on each contour as the puncture point.

[0070] It should be noted that the local range of a contour point refers to the contour segment in which the contour point is located. If both the vector change degree and the local intensity are greater, it indicates a greater intensity of contour change between the contour point's location and its local range, a more complex contour change at the contour point's location, and a lower probability that the contour point will be selected as a puncture point, thus resulting in a lower puncture preference. Therefore, both the vector change degree and the local intensity are negatively correlated with the puncture preference. In this embodiment of the invention, the ratio of the local intensity of the contour segment in which each contour point is located to the average local intensity of all contour segments is calculated and used as the change intensity coefficient of the contour segment in which each contour point is located; the product of the vector change degree of each contour point and the change intensity coefficient of its contour segment is negatively correlated and normalized to obtain the puncture preference. Since the angle between the two vectors is within a certain range... Then, the angle is normalized by the ratio of the angle between the unit tangent vectors of two adjacent contour points to 180°; the data to be processed is used as the exponent of an exponential function with the natural constant as the base to achieve negative correlation and normalization. Other embodiments can also use the Norm function or other methods to achieve normalization and negative correlation by taking the reciprocal, which will not be described here.

[0071] In one implementation of this invention, the preset direction is set to clockwise.

[0072] In one implementation of this invention, each contour is divided into 10 contour segments of equal length.

[0073] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the thermal response dominance is described in [reference needed]. Figure 2 The diagram illustrates a flowchart of a method for obtaining thermal response dominance according to an embodiment of the present invention, the method comprising:

[0074] Step S310: Take the reciprocal of the absolute value of the pixel value difference between the corresponding pixel points of the starting cutting point of the cutting crack in the local time period in the sheet metal infrared image at the start time and the end time, respectively, as the initial retention degree of heat accumulation.

[0075] It should be noted that if the difference in pixel value between the corresponding pixels in the sheet metal infrared images at the two start and end times is smaller, it indicates that the heat dissipation efficiency at the start cutting point is lower and the retention ratio is higher. In this case, the heat accumulation and retention during cutting is more severe and the initial heat accumulation retention is greater.

[0076] Step S320: Based on the pixel values ​​of the corresponding pixels on the cutting crack in all time-time sheet metal infrared images during the local time period, and the distance from the pixel on the cutting crack to the starting cutting point, obtain the thermal conductivity performance.

[0077] In one specific implementation of this invention, the thermal conductivity performance is expressed by the formula:

[0078]

[0079] In the formula, IA represents the thermal conductivity performance of the local time period; T represents the total number of moments within the local time period; and M represents the total number of contour points on the cutting crack in the local time period, excluding the starting cutting point. The distance from the starting point of the cutting crack on the local time segment to the remaining m-th contour point; Let be the pixel value of the m-th contour point on the cutting crack (excluding the starting cutting point) at time t in the sheet metal infrared image during a local time period. It should be noted that if the temperature of the m-th contour point on the cutting crack (excluding the starting cutting point) is higher and it is closer to the starting cutting point, then... smaller and The larger the value, the more significant the heat conduction from the m-th contour point to the starting cutting point, and the greater the heat conduction performance.

[0080] Step S330: Adjust the initial heat accumulation retention using thermal conductivity performance to obtain the heat accumulation retention for a local time period.

[0081] If the heat conduction from other contour points on the cutting crack to the starting cutting point is more significant during a local time period, delaying the natural heat dissipation of the starting cutting point and leading to an overestimation of the initial heat accumulation retention during the cutting process, then the initial heat accumulation retention should be reduced to obtain the final heat accumulation retention. In this embodiment of the invention, the heat conduction performance during the local time period is negatively correlated and normalized. The processing result is then used to weight the initial heat accumulation retention to obtain the final heat accumulation retention. This embodiment uses the heat conduction performance as the exponent of an exponential function with the natural constant as the base to achieve negative correlation and normalization. Other methods can also be used, which will not be elaborated here.

[0082] Step S340: Obtain the deformation risk level of the local time period based on the cutting position and heat accumulation retention level of the local time period.

[0083] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the deformation risk degree includes: designating the line segment connecting the two endpoints of the cutting crack in the sheet metal analysis image at the end of the local time period as the main stress line segment; designating the closed region formed by the cutting crack and the main stress line segment in the sheet metal analysis image at the end of the local time period as the cut region of the local time period; and obtaining the deformation risk degree based on the area of ​​the cut region and the heat accumulation retention rate of the local time period. Wherein, the area of ​​the region refers to the total number of pixels within the region.

[0084] It should be noted that the larger the area of ​​the cut region and the greater the heat accumulation retention, the more pronounced the downward tendency of the cut portion due to gravity, and the more severe the heat accumulation retention. This indicates a higher risk of thermal deformation at the main stress points, thus a greater deformation risk. Therefore, the area of ​​the cut region and the heat accumulation retention are both positively correlated with the deformation risk. In this embodiment of the invention, the product of the area of ​​the cut region and the heat accumulation retention for a local time period of each contour is used as the deformation risk for the corresponding local time period.

[0085] Step S350: Obtain the cutting crack width and laser beam diameter parameters for a local time period; based on the difference between the cutting crack width and laser beam diameter parameters for a local time period, and the deformation risk level, obtain the thermal response priority for the local time period.

[0086] The method for obtaining the cutting crack width in a local time period is as follows: For the current cutting crack region and the cutting crack in the sheet metal analysis image at the end of the local time period, draw a perpendicular line through each pixel on the cutting crack. The distance between the two intersection points of the perpendicular line and the current cutting crack region is taken as the local crack width of each pixel on the cutting crack. Calculate the average of the local crack widths of all pixels on the cutting crack, and use this average as the cutting crack width for the local time period. The laser beam diameter parameter at each moment within the local time period is read through the CNC device's operating parameter interface. The average of the laser beam diameter parameters at all moments within the local time period is taken as the laser beam diameter parameter for the local time period. The laser diameter parameter at each moment can be read in real time through the CNC system's operating parameter interface.

[0087] It should be noted that the closer the width of the cutting crack in a local time period is to the laser beam diameter parameter, the more uniformly the heat is conducted along the cutting path, which can suppress the expansion of the heat-affected zone, resulting in a better thermal response in that local time period. Conversely, the lower the deformation risk, the better the thermal response in that local time period. Therefore, the difference between the width of the cutting crack in a local time period and the laser beam diameter parameter, as well as the deformation risk, are negatively correlated with the thermal response dominance. In this embodiment, the absolute value of the difference between the width of the cutting crack in a local time period and the laser beam diameter parameter is calculated. The product of this absolute value and the deformation risk is then negatively correlated and normalized to obtain the thermal response dominance. This embodiment uses the data to be processed as the exponent of an exponential function with the natural constant as the base to achieve negative correlation and normalization. Other methods can also be used, which will not be elaborated here.

[0088] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the pulse demand degree includes: calculating the average value of the puncture preference of all pixels on the cutting crack in a local time period, denoted as the comprehensive preference degree; taking the ratio of the comprehensive preference degree of each local time period of each contour to the previous local time period as the adjustment coefficient of each local time period; and normalizing the product of the adjustment coefficient of each local time period of each contour and the thermal response preference degree of the previous local time period to obtain the pulse demand degree of each local time period of each contour.

[0089] It should be noted that the overall optimization degree reflects the complexity of the overall profile of the cutting crack in a local time period. A larger ratio indicates a lower overall profile complexity in each local time period compared to the previous one. To improve cutting efficiency, a higher pulse frequency can be applied to each local time period, resulting in a higher pulse demand. Conversely, a smaller thermal response optimization degree in the preceding local time period indicates a stronger excess heat in the previous period. To prevent heat accumulation across time periods, the pulse frequency in each local time period needs to be reduced, resulting in a lower pulse demand. Therefore, the adjustment coefficient of each local time period and the thermal response optimization degree of its preceding local time period are positively correlated with the pulse demand degree of each local time period. In this embodiment of the invention, the Norm function is used for normalization. Other normalization methods, such as function transformation, can also be used, and are not limited here.

[0090] Preferably, in some possible implementations of the embodiments of the present invention, the method for obtaining the preferred pulse frequency includes: calculating the ratio of the pulse demand of each local time segment of each contour to that of the previous local time segment, and multiplying the ratio by the actual pulse frequency of the previous local time segment as the preferred pulse frequency of each local time segment of each contour. It should be noted that if the ratio is larger, it indicates that the pulse frequency of the previous local time segment is insufficient to support the segmentation of each local time segment, and the pulse frequency of each local time segment should be increased to obtain the preferred pulse frequency.

[0091] This invention is now complete.

[0092] Example 2:

[0093] This invention also provides a schematic diagram of a computer device for a sheet metal laser cutting processing apparatus; please refer to [link / reference]. Figure 3 The computer device includes a memory 501, a processor 502, and a computer program 503 stored in the memory 501 and running on the processor 502. When the processor 502 executes the computer program 503, the computer device can perform any of the laser cutting processing methods of the sheet metal laser cutting processing apparatus described above.

[0094] Furthermore, this application also protects an apparatus that may include a memory and a processor, wherein the memory stores executable program code, and the processor is used to call and execute the executable program code to perform a laser cutting processing method of a sheet metal laser cutting processing apparatus provided in this application.

[0095] This embodiment can divide the device into functional modules based on the above method example. For example, each module can correspond to a separate function, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0096] When each module is divided according to its function, the device may also include a communication module, a signal analysis module, a complexity analysis module, and a positioning module. It should be noted that all relevant content of each step involved in the above method embodiments can be referenced from the functional descriptions of the corresponding functional modules, and will not be repeated here.

[0097] It should be understood that the device provided in this embodiment is used to perform the laser cutting processing method of the sheet metal laser cutting processing device described above, and therefore can achieve the same effect as the above implementation method.

[0098] When using integrated units, the device may include a processing module and a storage module. When applied to a workpiece, the processing module can be used to control and manage the workpiece's operations. The storage module can be used to support the execution of program code by the workpiece.

[0099] The processing module may be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits contained in conjunction with the disclosure of this application. The processor may also be a combination of functions that implement computing capabilities, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and a microprocessor, etc., and the storage module may be a memory.

[0100] Example 3:

[0101] This embodiment also provides a computer-readable storage medium storing computer program code. When the computer program code is run on a computer, the computer executes the above-described related method steps to implement the laser cutting processing method of the sheet metal laser cutting processing device provided in the above embodiment.

[0102] Example 4:

[0103] This embodiment also provides a computer program product. When the computer program product is run on a computer, it causes the computer to perform the above-mentioned related steps to realize the laser cutting processing method of the sheet metal laser cutting processing device provided in the above embodiment.

[0104] In this embodiment, the device, computer-readable storage medium, computer program product, or chip are all used to execute the corresponding methods provided above. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the corresponding methods provided above, and will not be repeated here.

[0105] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0106] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0107] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A laser cutting method of a sheet metal laser cutting processing apparatus, characterized by, The method comprises: Obtaining the contour in the cutting contour image; According to the degree of change of the direction of each contour point and its adjacent contour point on each contour, and the degree of change of the contour in the local range of each contour point, obtaining the puncture preference degree of each contour point, and selecting the puncture point of each contour; The sheet metal laser cutting processing device generates a cutting path based on the image, starts cutting at the puncture point position, and obtains the cutting gap of each local time period and the sheet metal infrared image at all times during the cutting process of each contour in real time; according to the pixel value difference of the starting cutting point of the cutting crack in the local time period in the corresponding pixel points in the sheet metal infrared image at the start and end times, the position and pixel value of the pixel point on the cutting crack, and the cutting position and cutting crack width, the heat response site preference degree of the local time period is obtained; According to the relative size of the puncture preference degree of the pixel point on the cutting crack of each local time period and the previous local time period of each contour, and the heat response site preference degree of the previous local time period, the pulse demand degree of each local time period is obtained; the relative size of the pulse demand degree of each local time period and the previous local time period of each contour is used to adjust the actual pulse frequency of the previous local time period, and the preferred pulse frequency of each local time period is obtained; the device uses the preferred pulse frequency to complete the cutting of each contour in real time; The heat response site preference degree of the local time period is obtained, comprising: The reciprocal of the absolute value of the pixel value difference of the starting cutting point of the cutting crack in the local time period in the corresponding pixel points in the sheet metal infrared image at the start and end times is taken as the heat accumulation initial retention degree; According to the pixel value of the pixel point on the cutting crack in the local time period in the corresponding pixel points in the sheet metal infrared image at all times, and the distance from the pixel point on the cutting crack to the starting cutting point, the heat conduction performance degree is obtained; The heat conduction performance degree is used to adjust the heat accumulation initial retention degree, and the heat accumulation retention degree of the local time period is obtained; According to the cutting position of the local time period and the heat accumulation retention degree, the deformation risk degree of the local time period is obtained; The cutting crack width and laser beam diameter parameters of the local time period are obtained; according to the difference between the cutting crack width and the laser beam diameter parameters of the local time period, and the deformation risk degree, the heat response site preference degree of the local time period is obtained.

2. The laser cutting method of the sheet metal laser cutting device according to claim 1, wherein, The puncture preference degree of each contour point of each contour is obtained, and the puncture point of each contour is selected, comprising: Obtaining the unit tangent vector of each contour point on each contour; the angle between the unit tangent vector of each contour point on each contour and the unit tangent vector of the next contour point in the preset direction is normalized to obtain the vector change degree of each contour point; Each contour is divided into contour segments, and the standard deviation of the slope of all contour points on the contour segment is calculated as the local intensity; According to the vector change degree of each contour point and the local intensity of the contour segment where each contour point is located, the puncture preference degree is obtained; The maximum value corresponding to the contour point in the puncture preference degree of all contour points on each contour is selected as the puncture point.

3. The laser cutting method of the sheet metal laser cutting device according to claim 1, wherein, The calculation formula of the heat conduction performance degree is as follows: In the formula, IA is the heat conduction performance degree of the local time period; T is the total number of time points in the local time period; M is the total number of the rest of the profile points on the cutting crack in the local time period except the starting cutting point; is the distance from the starting cutting point to the rest of the mth profile point on the cutting crack in the local time period; is the pixel value of the corresponding pixel point in the sheet metal infrared image at the tth time point of the rest of the mth profile point on the cutting crack in the local time period except the starting cutting point.

4. The laser cutting method of the sheet metal laser cutting apparatus according to claim 1, wherein, The method for obtaining the cutting gap of each local time period comprises: Real-time acquisition of sheet metal analysis image and the cut crack area in each contour cutting process at each time; The current cutting crack area of the local period is composed of the pixel points in the cut crack area of the sheet metal analysis image at the end time of the local period that do not correspond to the pixel point positions in the cut crack area of the sheet metal analysis image at the start time; the skeleton line of the current cutting crack area is extracted, which is recorded as the cutting crack of the local period; the pixel points in the sheet metal analysis image and the sheet metal infrared image at the same time are one-to-one corresponding.

5. The laser cutting method of the sheet metal laser cutting apparatus according to claim 4, wherein The acquisition of the deformation risk degree of the local period includes: The line segment connecting the two end points of the cutting crack in the sheet metal analysis image at the end time of the local period is recorded as the main stress line segment; the closed area composed of the cutting crack in the sheet metal analysis image at the end time of the local period and the main stress line segment is recorded as the cut area of the local period; According to the area of the cut area of the local period and the heat accumulation retention degree, the deformation risk degree is obtained.

6. The laser cutting method of the sheet metal laser cutting apparatus according to claim 2, wherein, The acquisition of the pulse demand degree of each local period includes: The average value of the puncture preference degree of all pixel points on the cutting crack of the local period is calculated, which is recorded as the comprehensive preference degree; The ratio of the comprehensive preference degree of each local period to the previous local period of each contour is taken as the adjustment coefficient of each local period; The product of the adjustment coefficient of each local period and the heat response preference degree of the previous local period is normalized to obtain the pulse demand degree of each local period of each contour.

7. The laser cutting method of the sheet metal laser cutting apparatus according to claim 1, wherein, The acquisition of the pulse frequency of each local period includes: The ratio of the pulse demand degree of each local period to the previous local period of each contour is calculated, and the product of the ratio and the actual pulse frequency of the previous local period is taken as the preferred pulse frequency of each local period of each contour.

8. The laser cutting method of the sheet metal laser cutting apparatus according to claim 1, wherein, The heat conduction performance degree is negatively correlated with the heat accumulation retention degree.

9. A sheet metal laser cutting processing apparatus characterized by comprising: The device includes a processor, which implements the steps of the laser cutting processing method of the sheet metal laser cutting processing device according to any one of claims 1 to 8.

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