Laser cutting and thermodynamic compensation method for high-precision assembly trestle skeleton

Abstract

The application discloses a skeleton laser cutting and thermodynamic compensation method for high-precision assembly trestle, through an integrated sensor fixed on the side of a laser head, real-time collection of environment data and transient physical field information of a steel cutting surface, prospective detection of thermodynamic characteristics such as temperature gradient and molten state of a cutting area, and provision of real-time and accurate input basis for subsequent adaptive control. According to the real-time state and characteristic change of the cutting surface obtained through prospective perception, laser cutting parameters such as power and speed are dynamically and adaptively adjusted, so as to actively control actual linear energy input, ensure that the input heat of cutting is within the yield limit of the material, and avoid extreme non-uniform temperature gradient and residual tensile stress accumulation at geometric mutations such as corners and sharp corners due to fixed parameters.

Description

Technical Field

[0001] This application relates to the fields of data processing and intelligent control technology, specifically to a method for laser cutting and thermodynamic compensation of the skeleton for high-precision assembled trestle bridges. Background Technology

[0002] Existing technology 1 discloses a control device for a laser cutting system. It adjusts the overall height of the laser head solely based on a single capacitive sensing signal to maintain a preset constant focal length. Its control logic is uniform and does not involve identifying the geometric features of the cutting path, nor does it dynamically adjust the cutting energy input and trajectory based on changes in the thermodynamic state of the workpiece during the cutting process. Because existing technology 1 uses constant cutting parameters and a single height-following strategy, it cannot detect and compensate for the localized thermal expansion constraints and residual stress caused by extreme non-uniform temperature gradients when cutting geometrically abrupt changes such as corners and sharp angles of a trestle frame. This results in irreversible deformations such as out-of-plane warping, twisting, and dimensional shrinkage in the cut component.

[0003] Prior art 2 discloses a laser cutting method and system for irregularly shaped parts based on machine vision. It focuses on improving processing efficiency by optimizing the idle movement path between multiple parts. Its core is macroscopic path planning, but it does not involve real-time monitoring and adaptive adjustment of process parameters for changes in the material's physical state caused by geometric changes and thermal accumulation effects during the cutting process within the contour of a single part. Prior art 2, when cutting a single complex component, neglects the coupling effect between the geometric features of the cutting path and thermodynamic effects, and uses fixed cutting parameters. This leads to concentrated residual tensile stress at corners and sharp edges, causing out-of-plane warping and dimensional shrinkage of the component, ultimately resulting in misalignment of holes required for high-precision assembly. Summary of the Invention

[0004] The main objective of this application is to provide a laser cutting and thermodynamic compensation method for the frame of high-precision assembled trestle bridges. This method addresses the problem that traditional laser cutting methods for steel structure assembled trestle bridge frames, which typically use fixed cutting parameters, suffer from extreme non-uniform temperature gradients between the high-temperature molten zone and the cold base material at corners, sharp edges, or non-straight cut edges. This drastic temperature difference restricts local metal expansion, and without trajectory compensation, irreversible residual tensile stress forms upon cooling, leading to out-of-plane warping, twisting, and dimensional shrinkage of the components. Furthermore, the accumulation of this torsional error during the assembly of different trestle frames ultimately results in misalignment of holes in key node plates, introducing significant initial assembly stress into the structure and severely weakening the trestle's load-bearing capacity and fatigue life.

[0005] To achieve the above objectives, the first aspect of this application provides a method for laser cutting and thermodynamic compensation of the skeleton of a high-precision assembled trestle, comprising:

[0006] During the laser cutting process, a follow-up multimodal sensing integrated module fixed to the side and rear of the laser cutting head is used to proactively collect transient physical field perception data and steel property data of the area to be cut.

[0007] Based on the transient physical field sensing data and steel property data, the critical temperature at which the steel yields within the elastic deformation range is calculated. Using the critical temperature as a constraint, and combining the steel property data and mechanical vibration data during the cutting process, the real-time laser cutting rate and laser cutting power are adaptively adjusted.

[0008] The actual line energy within the look-ahead cutting segment is calculated based on the adaptively adjusted real-time laser cutting power and real-time laser cutting rate, and the two-dimensional transient temperature gradient distribution is calculated based on the actual line energy.

[0009] The local temperature rise is calculated based on the two-dimensional transient temperature gradient distribution. The thermal strain tensor and the true total strain tensor are constructed in combination with the stiffness constraint of the steel. The true total strain tensor is then spatially integrated to obtain the macroscopic reverse compensation vector.

[0010] The real-time laser cutting rate, laser cutting power, and macroscopic reverse compensation vector are mapped into control commands, and the laser head is driven by a servo motor to perform reverse compensation cutting, so that the cut kerf falls back to the designed position after cooling.

[0011] Optionally, the step of using a follow-up multimodal sensing integrated module fixed to the side and rear of the laser cutting head to proactively collect transient physical field sensing data and steel property data of the area to be cut, including:

[0012] By using a miniature array infrared thermal imager and a non-contact laser displacement sensor integrated inside the module, the uncut length area behind the cutting hole is continuously scanned at a preset frame rate to obtain a relatively fixed comet-shaped thermal wake image.

[0013] Extract steel property data of the forward-looking cutting segment from the thermal wake image. The steel property data includes steel thickness, root mean square surface roughness, and cutting curvature. At the same time, extract real-time cutting process parameter data and vibration data at the current moment.

[0014] Optionally, the calculation of the critical temperature at which the steel yields within the elastic deformation range includes:

[0015] A thermal stress equation for a specific type of steel used in a trestle bridge is established, and the structural restraint coefficient and linear expansion coefficient are introduced.

[0016] Establish the functional relationship between the yield strength of steel and the temperature decay;

[0017] Let the thermal stress value of the thermal stress equation be equal to the yield strength at the current temperature, solve for the limit allowable temperature rise, and quickly obtain the critical temperature at which the steel will yield using the Newton iteration method.

[0018] Optionally, the step of adaptively adjusting the real-time laser cutting rate and laser cutting power by combining the steel property data and the mechanical vibration data during the cutting process includes:

[0019] The steel property factors of the look-ahead cutting segment are calculated based on the steel thickness, root mean square surface roughness, and cutting curvature of the look-ahead cutting segment.

[0020] Calculate the ratio of the laser cutting rate at the corresponding moment of the forward cutting segment to the laser cutting rate at the current moment. The ratio is equal to the ratio of the steel property factor of the forward cutting segment to the steel property factor of the cutting position at the current moment.

[0021] The laser cutting rate at the current moment is adjusted using the rate ratio as an adjustment coefficient.

[0022] The ratio of the change in the forward cutting segment to the change in the laser cutting rate at the current moment is used as an adjustment coefficient to coordinately adjust the laser cutting power at the current moment.

[0023] Optionally, the adaptive adjustment of the real-time laser cutting rate and laser cutting power includes:

[0024] Based on the ideal effective spot diameter and ideal center power density at the laser focus, the ideal power density under vibration-free conditions is calculated.

[0025] Based on the reciprocating offset caused by the lateral vibration of the machine tool or cutting head, calculate the effective diameter of the dynamic equivalent spot and the effective power density under vibration conditions.

[0026] Calculate the power density loss rate, which reflects the degree of power density attenuation caused by vibration;

[0027] Using the power density loss rate as a compensation factor and the real-time theoretical laser cutting power as the compensation base, the actual cutting power is calculated; and it is ensured that the heat input corresponding to the actual cutting power is lower than the heat input corresponding to the critical temperature. If it exceeds the critical temperature, the power corresponding to the critical heat input is used as the actual cutting power.

[0028] Optionally, the calculation of the actual linear energy within the look-ahead cutting segment based on the adaptively adjusted real-time laser cutting power and real-time laser cutting rate includes:

[0029] Calculate the actual input line energy of the look-ahead segment at the corresponding time. The actual input line energy is equal to the actual cutting power of the look-ahead segment at the corresponding time divided by the actual cutting rate, and then multiplied by the heat absorption rate of the steel.

[0030] Based on the actual input line energy, the two-dimensional transient temperature gradient distribution around the laser focus at the corresponding moment is calculated using the fast difference method.

[0031] Optionally, the step of calculating the local temperature rise based on the two-dimensional transient temperature gradient distribution and constructing the thermal strain tensor and the true total strain tensor in combination with the stiffness constraint of the steel includes:

[0032] Based on local temperature rise and linear expansion coefficient, the thermal strain tensor of isotropic materials is calculated. The thermal strain tensor only exists on the diagonal to represent the volume expansion trend.

[0033] A stiffness matrix is ​​constructed based on the material's elastic modulus and Poisson's ratio, and the real thermal stress tensor generated by the resistance to thermal expansion is calculated.

[0034] Based on the inverse form of the generalized Hooke's law, the three-dimensional expansion direction is forcibly coupled to calculate the elastic strain tensor.

[0035] Adding the thermal strain tensor to the elastic strain tensor yields the true total strain tensor, which reflects the predicted thermal deformation of the steel.

[0036] Optionally, it also includes:

[0037] During each interpolation cycle, the motion controller analyzes the machining trajectory, generates the real-time laser cutting power as the PWM duty cycle control signal of the laser generator, generates the real-time laser cutting rate as the speed feedforward signal of the servo motor, and reconstructs the macroscopic reverse compensation vector into a position command.

[0038] The reconstructed position command, PWM duty cycle control signal and speed feedforward signal are aligned with microsecond-level timestamps via an industrial real-time Ethernet bus with a distributed clock, and then synchronously sent to the laser generator and servo motor actuator.

[0039] To achieve the above objectives, a second aspect of this application also provides a laser cutting and thermodynamic compensation device for the skeleton of a high-precision assembled trestle, comprising:

[0040] The forward-looking perception module is used to proactively collect transient physical field perception data and steel property data of the area to be cut through a follow-up multimodal sensing integration module fixed to the side and rear of the laser cutting head during the laser cutting process.

[0041] The parameter adaptive adjustment module is used to calculate the critical temperature at which the steel yields within the elastic deformation range based on the transient physical field sensing data and the steel property data, and adaptively adjust the real-time laser cutting rate and laser cutting power by using the critical temperature as a constraint, combined with the steel property data and the mechanical vibration data during the cutting process.

[0042] The thermodynamic compensation calculation module is used to calculate the actual linear energy in the forward cutting segment based on the adaptively adjusted real-time laser cutting power and real-time laser cutting rate, and to calculate the two-dimensional transient temperature gradient distribution based on the actual linear energy; to calculate the local temperature rise based on the two-dimensional transient temperature gradient distribution, to construct the thermal strain tensor and the true total strain tensor in combination with the stiffness constraint of the steel, and to perform spatial integration on the true total strain tensor to obtain the macroscopic reverse compensation vector;

[0043] The instruction mapping and execution module is used to map the real-time laser cutting rate, laser cutting power, and macroscopic reverse compensation vector into control instructions, and drive the laser head to perform reverse compensation cutting through a servo motor.

[0044] To achieve the above objectives, a third aspect of this application also provides an electronic device, including a processor and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, it implements the skeleton laser cutting and thermodynamic compensation method for high-precision assembly bridges as provided above.

[0045] This application discloses a method for laser cutting and thermodynamic compensation of the skeleton of a high-precision assembled trestle. The method includes, during the laser cutting process, using a follow-up multimodal sensing integrated module fixed to the side and rear of the laser cutting head to proactively collect transient physical field sensing data and steel property data of the area to be cut; based on the transient physical field sensing data and steel property data, calculating the critical temperature at which the steel yields within the elastic deformation range, and using the critical temperature as a constraint, combined with the steel property data and mechanical vibration data during the cutting process, adaptively adjusting the real-time laser cutting rate and laser cutting power; based on... The adaptively adjusted real-time laser cutting power and real-time laser cutting rate are used to calculate the actual linear energy within the forward-looking cutting segment, and a two-dimensional transient temperature gradient distribution is calculated based on this actual linear energy. The local temperature rise is calculated based on this two-dimensional transient temperature gradient distribution, and a thermal strain tensor and a true total strain tensor are constructed in conjunction with the stiffness constraints of the steel. The true total strain tensor is then spatially integrated to obtain a macroscopic reverse compensation vector. The real-time laser cutting rate, laser cutting power, and macroscopic reverse compensation vector are mapped into control commands, and a servo motor drives the laser head to perform reverse compensation cutting, ensuring that the cut kerf falls back to the designed position after cooling. This scheme first utilizes integrated sensors for forward-looking perception of the transient physical field at the cutting edge: integrated sensors fixed to the side of the laser head collect environmental data and transient physical field information of the steel cutting surface in real time, performing forward-looking detection of thermodynamic characteristics such as the temperature gradient and melting state of the area to be cut, providing real-time and accurate input for subsequent adaptive control. Secondly, the adaptive cutting parameter adjustment function based on real-time status detection dynamically and adaptively adjusts laser cutting parameters (such as power and speed) based on the real-time status and characteristic changes of the cutting surface obtained through forward sensing. This proactively controls the actual linear energy input, ensuring that the input heat during cutting remains within the material's yield strength and avoiding extreme non-uniform temperature gradients and residual tensile stress accumulation at geometrically abrupt changes such as corners and sharp angles caused by fixed parameters. Finally, the trajectory reverse compensation function based on real-time linear energy and thermal expansion calculates and implements a real-time reverse compensation strategy for the cutting trajectory based on the actual linear energy and material thermal expansion corresponding to the real-time cutting parameters generated after adaptive adjustment. This proactively offsets dimensional deviations caused by thermal deformation, ensuring the geometric accuracy and shape stability of the cut component. This avoids the accumulation of errors during subsequent assembly, guaranteeing the load-bearing capacity and fatigue life of the trestle. Attached Figure Description

[0046] Figure 1 This application provides a laser cutting scenario for an embodiment of a laser cutting and thermodynamic compensation method for the skeleton of a high-precision assembled trestle.

[0047] Figure 2This is a schematic diagram of an embodiment of the laser cutting and thermodynamic compensation method for the skeleton of a high-precision assembled trestle in this application.

[0048] Figure 3 This is a flowchart illustrating an embodiment of the laser cutting and thermodynamic compensation method for the skeleton of a high-precision assembled trestle bridge, as provided in this application.

[0049] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0050] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0051] Existing laser cutting technologies (such as CN108422079B) rely solely on a single capacitive sensing signal to adjust the overall height of the laser head to maintain a preset constant focal length. Their control logic is uniform and does not involve identifying the geometric features of the cutting path, nor do they dynamically adjust the cutting energy input and trajectory based on changes in the thermodynamic state of the workpiece during the cutting process. Another existing technology (such as CN114239958B) focuses on improving processing efficiency by optimizing the idle movement path between multiple parts. Its core is macroscopic path planning, which does not involve real-time monitoring and adaptive adjustment of process parameters for changes in the physical state of materials caused by geometric changes and thermal accumulation effects during the cutting process within the contour of a single part. Therefore, when cutting geometrically abrupt points such as corners and sharp angles of a bridge frame, existing technologies cannot detect and compensate for the localized thermal expansion constraints and residual stress caused by extreme non-uniform temperature gradients. This leads to irreversible deformations such as out-of-plane warping, twisting, and dimensional shrinkage in the cut components, resulting in misalignment of holes required for high-precision assembly.

[0052] refer to Figure 2 and Figure 3 The first embodiment of this application provides a laser cutting and thermodynamic compensation method for the skeleton of a high-precision assembled trestle, addressing the technical problem in the prior art where the use of constant cutting parameters and a single height-following strategy fails to detect and compensate for localized thermal expansion constraints and residual stress caused by extreme non-uniform temperature gradients at geometric abrupt changes such as corners and sharp angles of the trestle skeleton. This results in irreversible deformations such as out-of-plane warping, twisting, and dimensional shrinkage in the cut components. This method can be executed by a processor, which can be located on a terminal or server. The execution process of the laser cutting and thermodynamic compensation method for the skeleton of a high-precision assembled trestle is as follows:

[0053] Step S101: During the laser cutting process, the transient physical field perception data and steel property data of the area to be cut are collected in advance by the follow-up multimodal sensing integration module fixed to the side and rear of the laser cutting head.

[0054] Step S102: Based on transient physical field sensing data and steel property data, calculate the critical temperature at which the steel yields within the elastic deformation range, and adaptively adjust the real-time laser cutting rate and laser cutting power by using the critical temperature as a constraint, combined with steel property data and mechanical vibration data during the cutting process.

[0055] Step S103: Calculate the actual line energy in the look-ahead cutting segment based on the adaptively adjusted real-time laser cutting power and real-time laser cutting rate, and calculate the two-dimensional transient temperature gradient distribution based on the actual line energy;

[0056] Step S104: Calculate the local temperature rise based on the two-dimensional transient temperature gradient distribution, construct the thermal strain tensor and the true total strain tensor in combination with the stiffness constraint of the steel, and perform spatial integration on the true total strain tensor to obtain the macroscopic reverse compensation vector.

[0057] Step S105: The real-time laser cutting rate, laser cutting power, and macroscopic reverse compensation vector are mapped into control commands. The laser head is driven by a servo motor to perform reverse compensation cutting, so that the cut kerf falls back to the designed position after cooling.

[0058] In one embodiment of this application, a follow-up multimodal sensing integrated module fixed to the side and rear of the laser cutting head is used to prospectively collect transient physical field perception data and steel property data of the area to be cut. This includes: continuously scanning the uncut length area behind the cutting hole at a preset frame rate using a miniature array infrared thermal imager and a non-contact laser displacement sensor integrated inside the module to obtain a relatively fixed comet-shaped thermal wake image; extracting steel property data of the prospective cutting segment from the thermal wake image, including steel thickness, root mean square surface roughness, and cutting curvature; and simultaneously extracting real-time cutting process parameter data and vibration data at the current moment.

[0059] In laser cutting scenarios involving the frame of prefabricated trestle bridges, existing methods typically follow fixed or pre-planned cutting patterns. However, due to variations in edge characteristics at different locations within the steel, a fixed heat input can lead to an extreme non-uniform temperature gradient between the high-temperature molten zone and the cold base material at the far end. This can cause out-of-plane warping and twisting of the components, weakening the trestle bridge's load-bearing capacity and fatigue life. Laser cutting scenarios such as... Figure 1As shown. To prevent the above situation, this embodiment optimizes the process by adaptively adjusting cutting parameters combined with trajectory compensation. Therefore, it is necessary to design a corresponding integrated sensor at the laser cutting head position to collect relevant data. This solution adopts a follow-up multimodal sensing integrated module. This module is fixed to the side and rear of the laser cutting head (along the wake region of the cutting feed direction), maintaining a relatively stationary local coordinate system with the cutting head. The acquisition module is jointly acquired by a miniature array infrared thermal imager and a non-contact laser displacement sensor integrated inside the module: Transient data acquisition: The infrared thermal imager continuously scans the uncut length area of ​​50mm to 200mm behind the cutting hole at a specific frame rate (e.g., 100Hz). Since the sensor moves synchronously with the cutting head, the image it acquires is a relatively fixed "comet-shaped" thermal wake. The system extracts real-time cutting process parameter data (cutting rate, cutting power) and steel property data (thickness, curvature, vibration) of the look-ahead section from it. In this embodiment, the sampling interpolation period is set to 3ms, so as to perform real-time sampling and precise control based on the interpolation period. Meanwhile, due to the severe high-frequency vibration, supersonic molten slag splashes, and complex spatial interference during the cutting process, a hollow truss-type cantilever made of composite materials such as aluminum alloy is used to fix the multimodal sensing integrated module. A micro-polymer damping pad is also designed to reduce measurement errors and ensure the accuracy of subsequent calculation results.

[0060] In an optional embodiment of this application, the calculation of the critical temperature at which the steel yields within the elastic deformation range includes: establishing a thermal stress equation for a specific steel material of the trestle when heated, introducing the structural restraint coefficient and the linear expansion coefficient; establishing a functional relationship between the yield strength of the steel and the temperature decay; setting the thermal stress value of the thermal stress equation equal to the yield strength at the current temperature, solving for the limit allowable temperature rise, and quickly obtaining the critical temperature at which the steel is about to yield using the Newton iteration method.

[0061] During the steel cutting process, the current fixed cutting parameters and lack of trajectory compensation can cause out-of-plane warping, twisting, and dimensional shrinkage of the steel components when encountering corners, sharp angles, or non-straight cut edges of the trestle frame due to extreme thermal gradients. To avoid these problems, this embodiment uses adaptive cutting parameters combined with trajectory compensation, ensuring that when the steel plate cools and shrinks back to its original position, the cut falls precisely at the designed location, achieving accurate cutting.

[0062] Since cutting steel requires a large amount of heat input, and the reverse compensation algorithm is highly dependent on the regularity and predictability of heat input deformation, ensuring the accuracy of reverse trajectory compensation requires that the thermal stress at the cutting position always remain within the yield strength of the material at the corresponding temperature. Yield strength depends on heat input, and the steel properties differ at different cutting positions. Therefore, it is necessary to adaptively adjust the cutting parameters to match the heat input to the cutting position and limit the heat input of the steel. First, determine the maximum heat input (temperature rise) corresponding to the steel within the elastic deformation range. The larger the heat input, the greater the thermal stress. If the heat input exceeds the maximum value, the deformation of the steel cannot be accurately predicted, thus preventing trajectory compensation. The following establishes the thermal stress equation for the specific steel of this trestle when heated. In this embodiment, the structural restraint coefficient is set to 0.6, and the linear expansion coefficient is set to 1.2 × 10⁻⁵ / ℃. Since the yield strength of steel is not constant but decreases with increasing temperature, its function is designed as follows: Based on the above two equations, setting the thermal stress value equal to the yield strength at the current temperature, the limit allowable temperature rise is calculated. Finally, the critical temperature at which the steel will yield is quickly obtained using Newton's iteration method. .in This refers to the highest temperature that the steel can withstand within its maximum yield strength. Therefore, using this temperature as a critical point, the fixed steel cutting process needs to be adaptively adjusted. When machining actual gantry frames, at cutting corners and variable cross-sections, the servo motor must physically slow down due to the mechanical inertia of the machine tool gantry. If the laser power remains unchanged during this slowdown, local energy accumulation will lead to heat buildup, exceeding the yield strength. Therefore, adaptive and coordinated control of laser speed and intensity is necessary during cutting to avoid localized overheating or uncontrolled molten pool formation.

[0063] In an optional embodiment of this application, the real-time laser cutting rate and laser cutting power are adaptively adjusted by combining steel property data and mechanical vibration data during the cutting process. This includes: calculating the steel property factor of the look-ahead cutting segment based on the steel thickness, root mean square surface roughness, and cutting curvature of the look-ahead cutting segment; calculating the ratio of the laser cutting rate at the corresponding moment of the look-ahead cutting segment to the laser cutting rate at the current moment, where the ratio is equal to the ratio of the steel property factor of the look-ahead cutting segment to the steel property factor at the current cutting position; adjusting the laser cutting rate at the current moment using the rate ratio as an adjustment coefficient; and coordinating the adjustment of the laser cutting power at the current moment using the ratio of the change in the laser cutting rate of the look-ahead cutting segment to the change in the laser cutting rate at the current moment as an adjustment coefficient.

[0064] During steel cutting, a forward-looking monitoring mechanism can acquire the steel properties within the area to be cut, allowing for adaptive determination of the laser cutting rate based on real-time monitoring results. Thicker plates and rougher cut surfaces require higher power for penetration, while the cutting speed must be reduced to ensure sufficient time for the molten pool to form and be blown away. Conversely, greater curvature at the corresponding location necessitates lower speeds to limit heat input. Therefore, for a given forward-looking cutting segment… In other words, it exists:

[0065]

[0066] In the formula Forward-looking segment Steel property factors. Forward-looking segment Surface root mean square roughness, For cutting segments The cutting curvature. This is the maximum thickness of the steel. Forward-looking segment The average thickness. Therefore, as the thickness and surface roughness of the steel in the forward section increase, as does the curvature, the cutting speed needs to be appropriately reduced to ensure the cutting effect. Conversely, if these factors decrease, the cutting speed should be appropriately increased to prevent heat buildup.

[0067] So for any current moment when cutting steel... In terms of its forward-looking phase corresponding The cutting rate at time t is:

[0068]

[0069] In the formula In the forward phase corresponding The laser cutting rate at any given time. For the current Laser cutting rate at any given time Forward-looking segment Steel property factors, For the current The steel property factor at the cutting position at any given time. This is achieved by comparing the difference in steel property factors between the area to be cut and the current cutting area, using this as a rate adjustment coefficient. The larger this ratio, the higher the corresponding laser cutting rate, and vice versa.

[0070] Therefore, for the cutting process, due to changes in the cutting rate, the corresponding cutting power should also be adjusted accordingly. When the rate decreases, the cutting power should be reduced; when the rate increases, the cutting power should be increased to maintain the cutting effect. Thus, this same process of adjusting the cutting power can be represented as:

[0071]

[0072] In the formula For the cutting process Laser cutting power at any given moment. For the current Laser cutting power at any given time Forward-looking segment laser cutting rate, For the current The laser cutting rate at the cutting position at any given time. Similarly, the change in the laser cutting rate is used as an adjustment coefficient to coordinately adjust the cutting power.

[0073] In an optional embodiment of this application, adaptive adjustment of the real-time laser cutting rate and laser cutting power includes: calculating the ideal power density under vibration-free conditions based on the ideal effective spot diameter and ideal center power density at the laser focal point; calculating the effective diameter of the dynamic equivalent spot and the effective power density under vibration conditions based on the reciprocating offset caused by the lateral vibration of the machine tool or cutting head; calculating the power density loss rate, which reflects the degree of power density attenuation caused by vibration; calculating the actual cutting power using the power density loss rate as a compensation factor and the real-time theoretical laser cutting power as the compensation base; and ensuring that the heat input corresponding to the actual cutting power is lower than the heat input corresponding to the critical temperature, and if it exceeds the critical temperature, then the power corresponding to the critical heat input is used as the actual cutting power.

[0074] It is important to note that mechanical vibrations occur during the actual operation of laser cutting machines. These vibrations cause severe dissipation of the "effective power density" acting on the steel plate. Therefore, cutting based on the theoretical power adjustment values ​​calculated above will fail to achieve the desired cutting effect due to vibration. Thus, the actual real-time power input needs to be determined by considering the power loss caused by vibration.

[0075] When the machine tool or cutting head vibrates laterally, the laser spot will shift back and forth at a high frequency along its original trajectory, causing the laser energy to be "spread" over a larger effective area, reducing the energy input density and resulting in poor cutting effect. Therefore, this step adjusts the laser cutting power in conjunction with the effect of vibration.

[0076] In an ideal, vibration-free state, assuming the effective spot diameter of the laser beam at the focal point is... (Typically between 0.2mm and 0.5mm), the total laser power is Based on existing technology, its ideal central power density can be calculated as follows: When vibration occurs, the effective diameter of this vibrating "dynamic equivalent light spot" is approximately... The corresponding effective power density is Therefore, its power density loss rate can be expressed as:

[0077]

[0078] This represents the power density loss rate caused by vibration. The larger the value, the greater the power density loss rate caused by the cutting vibration, and the more the cutting power is attenuated.

[0079] The power loss caused by vibration needs to be compensated, and the power density loss rate can be used as a compensation factor to cut the laser in real time.

[0080]

[0081] The actual cutting power at any given moment. The theoretical laser cutting power at any given moment. This represents the power density loss rate due to vibration. In other words, the actual cutting power of the laser in real-time steel cutting is determined through the compensation method described above.

[0082] In an optional embodiment of this application, the calculation of the actual line energy within the look-ahead cutting segment based on the adaptively adjusted real-time laser cutting power and real-time laser cutting rate includes: calculating the actual input line energy of the look-ahead segment at the corresponding moment, wherein the actual input line energy is equal to the actual cutting power of the look-ahead segment at the corresponding moment divided by the actual cutting rate, and then multiplied by the thermal absorption rate of the steel; and calculating the two-dimensional transient temperature gradient distribution around the laser focus at the corresponding moment using the fast difference method based on the actual input line energy.

[0083] During laser cutting, extreme thermal gradients can cause out-of-plane warping, twisting, and dimensional shrinkage in steel components. These thermal gradients are caused by the heat input, and the actual cutting parameters determine the amount of energy input. Therefore, the look-ahead segment is first determined based on the cutting parameters. (Trajectory compensation segment) at a certain future moment Actual linear energy:

[0084]

[0085] exist The actual input line energy at any given moment. exist The actual cutting power at all times. exist The actual cutting rate at any given moment. Therefore, the heat absorption rate of steel.

[0086] This represents the temperature rise caused by the linear energy input during cutting. The more drastic the temperature rise, the greater the thermal expansion of the corresponding steel, resulting in more severe warping and twisting after cooling; conversely, the less drastic the temperature rise, the less severe the warping and twisting. Therefore, the next step is to determine the compensation vector based on the thermal expansion caused by the temperature gradient.

[0087] In an optional embodiment of this application, the calculation of local temperature rise based on two-dimensional transient temperature gradient distribution, combined with the stiffness constraints of steel, to construct thermal strain tensors and true total strain tensors includes: calculating the thermal strain tensor of isotropic materials based on local temperature rise and linear expansion coefficient, wherein the thermal strain tensor only exists on the diagonal to represent the volume expansion trend; constructing a stiffness matrix based on the material's elastic modulus and Poisson's ratio, and calculating the true thermal stress tensor generated by the resistance to thermal expansion; forcibly coupling the three-dimensional expansion direction based on the inverse form of the generalized Hooke's law, and calculating the elastic strain tensor; and adding the thermal strain tensor and the elastic strain tensor to obtain the true total strain tensor reflecting the predicted results of steel thermal deformation.

[0088] This calculation focuses on the localized thermal expansion of the steel. In the actual steel trestle, the laser heat source is a "point." When this point expands due to heat, it simultaneously compresses the surrounding cold steel in all directions. This simultaneous tensile, compressive, and shearing tendency in three-dimensional space along various coordinate axes is represented by a second-order tensor (3×3 matrix) to accurately express the state of the microscopic volume element of thermal expansion.

[0089] First, the thermal strain tensor is extracted, which involves calculating the intrinsic thermal expansion trend at the cut-heated location. Assuming the material is isotropic (with the same expansion rate in all directions), the thermal strain tensor only has values ​​on the diagonal (i.e., only volume expansion, no shear deformation):

[0090]

[0091] In the formula Let α be the thermal strain tensor at the cutting position corresponding to a future time m. Let α be the coefficient of linear expansion, and ΔT be the local temperature rise. Let Kronecker function be the thermal strain tensor. Therefore, the larger the thermal strain tensor, the greater the expansion of the steel at that location due to heat, and vice versa.

[0092] Since the steel plate is not freely suspended at the cut point, it has internal stiffness, and its thermal expansion will encounter resistance from the surrounding material. The system must construct a stiffness matrix using the material's elastic modulus and Poisson's ratio to calculate the actual thermal stress tensor generated by the hindered thermal expansion. The elastic strain tensor was calculated based on the inverse form of the generalized Hooke's law. This involves establishing a three-dimensional "linkage protocol" based on material stiffness constraints regarding expansion, forcibly coupling the originally isolated three-dimensional expansion directions together to obtain a prediction result that accurately reflects the thermal deformation of steel. Therefore, the following exists:

[0093]

[0094] In the formula This represents the true total strain tensor at the corresponding cutting location. This represents the thermal strain tensor at the corresponding cutting position. This represents the elastic strain tensor generated at the corresponding location.

[0095] Since the true total strain tensor represents the actual stress change at the corresponding location in the steel during cutting, and this stress change ultimately leads to steel distortion, compensation is determined based on this true total strain tensor. Here, based on partial differential equations, the strain tensor over the entire look-ahead region is spatially integrated to obtain the macroscopic reverse compensation vector:

[0096]

[0097] So This represents the actual displacement of trajectory compensation segment k due to thermal expansion. Since the steel plate expands outward at this point... In order for the final cooling gap to fall back to its original position, the cutting head must be shifted in the opposite direction in advance. This achieves the compensation effect.

[0098] In an optional embodiment of this application, the method further includes: within each interpolation cycle, the motion controller analyzes the machining trajectory, generates the real-time laser cutting power as a PWM duty cycle control signal for the laser generator, generates the real-time laser cutting rate as a speed feedforward signal for the servo motor, and reconstructs the macroscopic reverse compensation vector into a position command; through an industrial real-time Ethernet bus with a distributed clock, the reconstructed position command, the PWM duty cycle control signal, and the speed feedforward signal are aligned with microsecond-level timestamps and synchronously sent to the laser generator and the servo motor actuator.

[0099] Based on the real-time cutting parameters and trajectory compensation displacement calculated in the above steps, the motion controller analyzes the machining trajectory in each interpolation cycle through energy domain mapping and spatial domain mapping. This generates a PWM duty cycle control signal for the laser generator and a speed feedforward signal for the servo motor. The reconstructed position command, PWM duty cycle control signal, and speed feedforward signal are then aligned with microsecond-level timestamps via an industrial real-time Ethernet bus with a distributed clock, and synchronously sent to the corresponding actuators to drive the laser head to complete the compensation cutting. This ensures the geometric accuracy and shape stability of the cut component, preventing misalignment of holes during subsequent assembly.

[0100] To address the aforementioned technical problems, the second embodiment of this application provides a laser cutting and thermodynamic compensation device for the skeleton of a high-precision assembled trestle, to solve the same technical problems as the method embodiment. The device 1000 may include the following modules: a forward sensing module 1001, a parameter adaptive adjustment module 1002, a thermodynamic compensation calculation module 1003, and an instruction mapping execution module 1004.

[0101] Among them, the forward-looking perception module 1001 is used to forward-lookingly collect transient physical field perception data and steel property data of the area to be cut through a follow-up multimodal sensing integration module fixed to the side and rear of the laser cutting head during the laser cutting process.

[0102] The parameter adaptive adjustment module 1002 is used to calculate the critical temperature at which the steel yields within the elastic deformation range based on transient physical field sensing data and steel property data. Using the critical temperature as a constraint, and combining the steel property data and mechanical vibration data during the cutting process, it adaptively adjusts the real-time laser cutting rate and laser cutting power.

[0103] The thermodynamic compensation calculation module 1003 is used to calculate the actual linear energy in the forward-looking cutting segment based on the adaptively adjusted real-time laser cutting power and real-time laser cutting rate, and to calculate the two-dimensional transient temperature gradient distribution based on the actual linear energy; to calculate the local temperature rise based on the two-dimensional transient temperature gradient distribution, to construct the thermal strain tensor and the true total strain tensor in combination with the stiffness constraint of the steel, and to perform spatial integration on the true total strain tensor to obtain the macroscopic reverse compensation vector.

[0104] The instruction mapping and execution module 1004 is used to map the real-time laser cutting rate, laser cutting power and macroscopic reverse compensation vector into control instructions, and drive the laser head to perform reverse compensation cutting through the servo motor.

[0105] It is understood that this embodiment is the apparatus corresponding to the method claim, and therefore this embodiment has all the technical effects of the method embodiment, which will not be repeated here.

[0106] To address the aforementioned technical problems, the third embodiment of this application provides an electronic device, including a processor and a memory. The memory stores a computer program, which, when executed by the processor, implements the laser cutting and thermodynamic compensation method for the skeleton of a high-precision assembly bridge as provided in the previous embodiments.

[0107] It is understood that this embodiment is the device corresponding to the method claim, and therefore this embodiment has all the technical effects of the method embodiment, which will not be repeated here.

[0108] It is understood that this embodiment is a storage medium corresponding to the method claim, therefore all the technical effects of the method embodiment are present in this embodiment, and will not be repeated here. The above are only preferred embodiments of this application, and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made based on the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for laser cutting and thermodynamic compensation of the skeleton of a high-precision assembled trestle, characterized in that, include: During the laser cutting process, a follow-up multimodal sensing integrated module fixed to the side and rear of the laser cutting head is used to proactively collect transient physical field perception data and steel property data of the area to be cut. Based on the transient physical field sensing data and steel property data, the critical temperature at which the steel yields within the elastic deformation range is calculated. Using the critical temperature as a constraint, and combining the steel property data and mechanical vibration data during the cutting process, the real-time laser cutting rate and laser cutting power are adaptively adjusted. The actual line energy within the look-ahead cutting segment is calculated based on the adaptively adjusted real-time laser cutting power and real-time laser cutting rate, and the two-dimensional transient temperature gradient distribution is calculated based on the actual line energy. The local temperature rise is calculated based on the two-dimensional transient temperature gradient distribution. The thermal strain tensor and the true total strain tensor are constructed in combination with the stiffness constraint of the steel. The true total strain tensor is then spatially integrated to obtain the macroscopic reverse compensation vector. The real-time laser cutting rate, laser cutting power, and macroscopic reverse compensation vector are mapped into control commands, and the laser head is driven by a servo motor to perform reverse compensation cutting, so that the cut kerf falls back to the designed position after cooling.

2. The method for laser cutting and thermodynamic compensation of the skeleton for high-precision assembled trestle bridges as described in claim 1, characterized in that, The aforementioned system uses a follow-up multimodal sensing integrated module fixed to the side and rear of the laser cutting head to proactively collect transient physical field sensing data and steel property data of the area to be cut, including: By using a miniature array infrared thermal imager and a non-contact laser displacement sensor integrated inside the module, the uncut length area behind the cutting hole is continuously scanned at a preset frame rate to obtain a relatively fixed comet-shaped thermal wake image. Extract steel property data of the forward-looking cutting segment from the thermal wake image. The steel property data includes steel thickness, root mean square surface roughness, and cutting curvature. At the same time, extract real-time cutting process parameter data and vibration data at the current moment.

3. The method for laser cutting and thermodynamic compensation of the skeleton for high-precision assembled trestle bridges as described in claim 1, characterized in that, The calculation of the critical temperature at which steel yields within the elastic deformation range includes: A thermal stress equation for a specific type of steel used in a trestle bridge is established, and the structural restraint coefficient and linear expansion coefficient are introduced. Establish the functional relationship between the yield strength of steel and the temperature decay; Let the thermal stress value of the thermal stress equation be equal to the yield strength at the current temperature, solve for the limit allowable temperature rise, and quickly obtain the critical temperature at which the steel will yield using the Newton iteration method.

4. The method for laser cutting and thermodynamic compensation of the skeleton of a high-precision assembled trestle as described in claim 2, characterized in that, The method of adaptively adjusting the real-time laser cutting rate and laser cutting power by combining the steel property data and the mechanical vibration data during the cutting process includes: The steel property factors of the look-ahead cutting segment are calculated based on the steel thickness, root mean square surface roughness, and cutting curvature of the look-ahead cutting segment. Calculate the ratio of the laser cutting rate at the corresponding moment of the forward cutting segment to the laser cutting rate at the current moment. The ratio is equal to the ratio of the steel property factor of the forward cutting segment to the steel property factor of the cutting position at the current moment. The laser cutting rate at the current moment is adjusted using the rate ratio as an adjustment coefficient. The ratio of the change in the forward cutting segment to the change in the laser cutting rate at the current moment is used as an adjustment coefficient to coordinately adjust the laser cutting power at the current moment.

5. The method for laser cutting and thermodynamic compensation of the skeleton of a high-precision assembled trestle as described in claim 4, characterized in that, The adaptive adjustment of real-time laser cutting rate and laser cutting power includes: Based on the ideal effective spot diameter and ideal center power density at the laser focus, the ideal power density under vibration-free conditions is calculated. Based on the reciprocating offset caused by the lateral vibration of the machine tool or cutting head, calculate the effective diameter of the dynamic equivalent spot and the effective power density under vibration conditions. Calculate the power density loss rate, which reflects the degree of power density attenuation caused by vibration; Using the power density loss rate as a compensation factor and the real-time theoretical laser cutting power as the compensation base, the actual cutting power is calculated; and it is ensured that the heat input corresponding to the actual cutting power is lower than the heat input corresponding to the critical temperature. If it exceeds the critical temperature, the power corresponding to the critical heat input is used as the actual cutting power.

6. The method for laser cutting and thermodynamic compensation of the skeleton of a high-precision assembled trestle as described in claim 1, characterized in that, The calculation of the actual linear energy within the look-ahead cutting segment based on the adaptively adjusted real-time laser cutting power and real-time laser cutting rate includes: Calculate the actual input line energy of the look-ahead segment at the corresponding time. The actual input line energy is equal to the actual cutting power of the look-ahead segment at the corresponding time divided by the actual cutting rate, and then multiplied by the heat absorption rate of the steel. Based on the actual input line energy, the two-dimensional transient temperature gradient distribution around the laser focus at the corresponding moment is calculated using the fast difference method.

7. The method for laser cutting and thermodynamic compensation of the skeleton of a high-precision assembled trestle as described in claim 6, characterized in that, The calculation of local temperature rise based on the two-dimensional transient temperature gradient distribution, combined with the stiffness constraints of the steel, to construct the thermal strain tensor and the true total strain tensor includes: Based on local temperature rise and linear expansion coefficient, the thermal strain tensor of isotropic materials is calculated. The thermal strain tensor only exists on the diagonal to represent the volume expansion trend. A stiffness matrix is ​​constructed based on the material's elastic modulus and Poisson's ratio, and the real thermal stress tensor generated by the resistance to thermal expansion is calculated. Based on the inverse form of the generalized Hooke's law, the three-dimensional expansion direction is forcibly coupled to calculate the elastic strain tensor. Adding the thermal strain tensor to the elastic strain tensor yields the true total strain tensor, which reflects the predicted thermal deformation of the steel.

8. The method for laser cutting and thermodynamic compensation of the skeleton for high-precision assembled trestle bridges as described in claim 1, characterized in that, Also includes: During each interpolation cycle, the motion controller analyzes the machining trajectory, generates the real-time laser cutting power as the PWM duty cycle control signal of the laser generator, generates the real-time laser cutting rate as the speed feedforward signal of the servo motor, and reconstructs the macroscopic reverse compensation vector into a position command. The reconstructed position command, PWM duty cycle control signal and speed feedforward signal are aligned with microsecond-level timestamps via an industrial real-time Ethernet bus with a distributed clock, and then synchronously sent to the laser generator and servo motor actuator.

9. A laser cutting and thermodynamic compensation device for the skeleton of a high-precision assembled trestle, characterized in that, include: The forward-looking perception module is used to proactively collect transient physical field perception data and steel property data of the area to be cut through a follow-up multimodal sensing integration module fixed to the side and rear of the laser cutting head during the laser cutting process. The parameter adaptive adjustment module is used to calculate the critical temperature at which the steel yields within the elastic deformation range based on the transient physical field sensing data and the steel property data, and adaptively adjust the real-time laser cutting rate and laser cutting power by using the critical temperature as a constraint, combined with the steel property data and the mechanical vibration data during the cutting process. The thermodynamic compensation calculation module is used to calculate the actual line energy in the look-ahead cutting segment based on the adaptively adjusted real-time laser cutting power and real-time laser cutting rate, and to calculate the two-dimensional transient temperature gradient distribution based on the actual line energy. The local temperature rise is calculated based on the two-dimensional transient temperature gradient distribution. The thermal strain tensor and the true total strain tensor are constructed in combination with the stiffness constraint of the steel. The true total strain tensor is then spatially integrated to obtain the macroscopic reverse compensation vector. The instruction mapping and execution module is used to map the real-time laser cutting rate, laser cutting power, and macroscopic reverse compensation vector into control instructions, and drive the laser head to perform reverse compensation cutting through a servo motor.

10. An electronic device, characterized in that, It includes a processor and a memory, wherein the memory stores a computer program, which, when executed by the processor, implements the method for laser cutting and thermodynamic compensation of the skeleton for high-precision assembly trestle as described in any one of claims 1 to 8.

Images