Plate laser-flame hybrid cutting device and cutting method

Abstract

The present application relates to the technical field of plate cutting processing, and discloses a plate laser-flame composite cutting device and a cutting method, which comprise a numerical control system, a cutting head body, a Z-axis unit, a gantry beam unit, a follow-up thickness measuring unit, a self-adaptive process pre-planning module and a multi-stage safety control logic unit electrically connected with the numerical control system, the cutting head body is connected to the Z-axis unit, the Z-axis unit realizes left and right movement in the Y-axis direction, the gantry beam unit realizes forward and backward movement in the X-axis direction through a linear guide rail, and the follow-up thickness measuring unit, the self-adaptive process pre-planning module and the multi-stage safety control logic unit are electrically connected with the numerical control system, the present application realizes high-quality and high-safety automatic cutting of variable-thickness plates by introducing thickness pre-scanning before cutting, cutting drawing track mapping, process pre-planning based on path thickness change and a three-stage progressive safety control architecture, and solves the problems of insufficient thickness self-adaptive capability, manual process switching and imperfect safety mechanism in the prior art.

Description

Technical Field

[0001] This invention relates to the field of sheet metal cutting and processing technology, and in particular to a laser-flame composite cutting device and method for sheet metal. Background Technology

[0002] Laser cutting and flame cutting are two mainstream thermal cutting technologies in the field of metal sheet processing. Laser cutting has the advantages of narrow kerf, small heat-affected zone, and high precision, making it suitable for high-speed, high-precision processing of medium and thin plates. Flame cutting has the advantages of low equipment cost and a wide cutting thickness range, making it suitable for processing thick plates. To combine the advantages of both processes, existing laser-flame hybrid cutting equipment can switch between the two modes according to the thickness of the sheet. However, existing laser-flame hybrid cutting equipment still has the following technical shortcomings in practical applications: 1) Lack of thickness adaptive capability Existing equipment typically requires manual measurement of the sheet thickness or direct input of the nominal thickness before cutting, followed by manual selection of the cutting mode. When the actual sheet thickness fluctuates (e.g., due to rolling tolerances, localized corrosion, or reinforcing ribs) or the sheet is warped, the cutting process parameters (e.g., gas pressure, cutting speed, focal point position) cannot be dynamically matched, leading to quality problems such as incomplete cuts, severe slag buildup, and overheating. This is particularly problematic in the processing of variable cross-section sheets (e.g., wedge plates for shipbuilding, structural components with reinforcing ribs), where the lack of ability to predict thickness changes along the cutting path prevents the process parameters from smoothly transitioning with thickness variations.

[0003] (ii) Process switching relies on manual intervention For sheet materials in the transition zone between the upper limit of laser cutting and the lower limit of flame cutting, existing equipment cannot automatically decide whether to use pure laser, pure flame, or a hybrid cutting mode. Operators must rely on experience to make judgments, which not only increases labor costs but also leads to inconsistent processing quality due to differences in experience.

[0004] (iii) Inadequate security control mechanisms Laser-flame hybrid equipment involves both a laser generating unit and a gas supply unit. Defects in the control logic could lead to serious safety accidents. Existing safety measures in such equipment mostly rely on physical protective shields or single-sensor monitoring, which presents the following problems: 1. Physical protective shield interlocking technology, such as the invention disclosed in European Patent Application No. EP20185983, application date 2017-01-11, authorization (publication) No. EP3756817B1, authorization (publication) date 2023-05-24, which discloses a laser cutting tool with an interlocking switch protective housing and a method for assembling such laser cutting tools. While this technology can prevent accidental contact, it cannot solve the risk of implosion caused by gas circuit logic errors. 2. Some equipment, such as the invention disclosed in publication number CN119187885A, dated 2024-12-27, is a three-in-one laser-flame composite cutting system with dual height tracking. Through intelligent switching, fault self-diagnosis, path optimization, and cloud-based linkage technologies, it solves the limitations of traditional laser and flame cutting systems. However, this technology employs a strategy of automatically switching cutting modes in case of faults. While this strategy prioritizes continuous production, improper mode switching may expand the scope of the fault. 3. Lack of hardware-level backup protection independent of the CNC system means that the equipment cannot be safely shut down when the control system fails.

[0005] (iv) Limitations of existing patented technologies A search revealed that Wuhan Xinxi Intelligent Technology Co., Ltd.'s patent application publication number CN119187885A, published on 2024-12-27, discloses a three-in-one laser flame composite cutting system with dual height tracking. Its core technical feature is "real-time height feedback and dynamic adjustment of process parameters during the cutting process." While this solution can handle a certain degree of thickness fluctuation, its "real-time feedback" mechanism has the following inherent defects: Sensor detection lag prevents timely response at points of abrupt thickness changes, leading to decreased cutting quality in the transition zone; the inability to predict thickness changes along the cutting path before cutting results in reactive adjustments to process parameters; and the lack of spatial mapping with customer cutting drawings hinders the ability to pre-plan thickness variations along the path.

[0006] Furthermore, Mesek Machinery's European patent EP3756817B1 relates to physical protective covers and mechanical interlock switches, and Hubei Weisuda's invention, published on August 2, 2024, with publication number CN118417699A, discloses a multi-airway anti-fog and explosion-proof flame laser fusion cutting device, which relates to the hardware structure of a flashback device. Both of these inventions have different technical approaches from the software-defined logic interlock of this invention.

[0007] Therefore, developing a laser-flame composite cutting device that can achieve pre-scanning of thickness before cutting, pre-planning of cutting path process, smooth transition of parameters in the transition zone, and has multi-level safety interlocking functions has significant technical value and market application prospects. Summary of the Invention

[0008] This invention aims to overcome the shortcomings of existing technologies by providing a laser-flame composite cutting device for sheet metal. By introducing pre-scanning of thickness before cutting, mapping of cutting blueprint trajectories, pre-planning of processes based on path thickness variations, and a three-level progressive safety control architecture, this invention achieves high-quality, high-safety automated cutting of sheet metal with varying thicknesses, solving the technical problems of insufficient thickness adaptability, reliance on manual process switching, and imperfect safety mechanisms in existing technologies.

[0009] This invention also provides a method for laser-flame composite cutting of sheet metal.

[0010] The technical solution adopted by this invention to solve its technical problem is: A laser flame composite cutting device for sheet metal includes a cutting head body, a Z-axis unit, a gantry beam unit, a cutting table unit, a bed unit, and a CNC system. The cutting head body, Z-axis unit, and gantry beam unit are electrically connected to the CNC system. The cutting head body is connected to the Z-axis unit. The Z-axis unit achieves left-right movement in the Y-axis direction via linear guides. The gantry beam unit achieves forward-backward movement in the X-axis direction via linear guides. The device also includes a follow-up thickness measurement unit, an adaptive process pre-planning module, and a multi-level safety control logic unit. The follow-up thickness measurement unit, adaptive process pre-planning module, and multi-level safety control logic unit are electrically connected to the CNC system. The follow-up thickness measurement unit is used to perform plate thickness scanning before cutting and generate a two-dimensional plate thickness distribution map. The follow-up thickness measurement unit includes a displacement sensor installed on the cutting head body and the displacement sensor is connected to the CNC system. The adaptive process pre-planning module is used to complete the process segmentation, transition zone parameter interpolation, and process parameter sequence calculation before cutting based on the scanned thickness data. The multi-level safety control logic unit is used to implement a three-level progressive safety control system, including software-defined gas circuit logic interlock, graded early warning and manual confirmation, and independent hardware safety loops. The independent hardware safety loops are mounted on the oxygen gas circuit and the gas gas circuit to control the opening and closing of the gas circuit, and are mounted on the laser to control the opening and closing of the light shutter. The independent hardware is electrically connected to the system.

[0011] The displacement sensor is either a capacitive displacement sensor or a laser triangulation distance sensor.

[0012] The adaptive process pre-planning module includes: Process section division unit: Based on the plate thickness variation curve, the cutting path is divided into a constant thickness section and a transition section, where the transition section refers to the section where the plate thickness variation exceeds a preset threshold T. max The area; Gas pressure calculation unit: Embedded gas pressure calculation model based on plate thickness; Process parameter sequence generation unit: Generates the calculation results into a process parameter sequence containing the cutting mode, gas pressure, cutting speed, and focal position corresponding to the cutting trajectory points, and preloads it into the execution buffer of the CNC system.

[0013] The multi-level security control logic unit includes: Logic interlock layer: The software-defined gas path logic interlock is implemented by the interlock logic matrix built into the CNC system. The interlock logic matrix includes laser-gas interlock, ignition-gas supply timing interlock and mode exclusive lock, and does not rely on the mechanical switch of the physical protective cover. Real-time monitoring layer: Includes pressure sensor, displacement sensor and temperature sensor. When the monitored parameters reach the preset threshold, it will issue a graded warning and prevent automatic switching of cutting mode in fault condition, and keep the equipment status pending manual confirmation. Emergency response layer: includes a hardware safety loop independent of the CNC system. The hardware safety loop includes a watchdog timer, a redundant shut-off actuator consisting of a normally closed solenoid valve and a manual shut-off valve connected in series, and a rupture disc pressure relief device located inside the cutting head.

[0014] The tiered early warning system of the real-time monitoring layer includes: Level 1 warning: When the distance between the cutting head and the material is less than the safe distance D safe At this time, the feed speed is reduced and the cutting head is not automatically raised; Level 2 warning: When the gas pressure is lower than the lower limit threshold, the feeding motion is suspended, the gas purging state is maintained, an audible and visual alarm is issued, and manual confirmation is required. Level 3 warning: When the temperature of the cutting area exceeds the upper limit threshold, stop the cutting action, continue purging, issue an audible and visual alarm, and resume after manual reset; Emergency Warning: When a backfire signal is detected, the main gas valve will be shut off within 0.1 seconds, nitrogen purging will be initiated, and emergency procedures will be executed.

[0015] A cutting method using a laser-flame composite cutting device, comprising the following steps: S1: Before the cutting program starts, the CNC system controls the drive mechanism to move the cutting head along the preset scanning path, and the sensor measures the Z-axis displacement Z of the cutting head relative to the reference plane of the cutting table in real time. real (x,y), the CNC system uses the formula T(x,y=Z base -Z real (x,y) Calculates the actual thickness T(x,y) of the plate at the coordinate point (x,y), where Z base The calibrated height of the cutting head from the reference plane of the cutting table under no-load conditions is used to generate a two-dimensional plate thickness distribution map after scanning. S2: Import the customer's cutting drawing, register the cutting trajectory coordinates with the plate thickness distribution map in spatial coordinates, and generate the plate thickness variation curve T(s) along the cutting path; S3: Divide the plate thickness into constant thickness and transition sections based on the plate thickness variation curve T(s). The transition section refers to the plate thickness variation exceeding a preset threshold T. max The area; S4: For the transition section, a progressive process switching algorithm is used to calculate the process parameters of each cutting point; S6: Perform the cutting operation according to the pre-planned sequence of process parameters.

[0016] Step S2 includes: S21: Import the cutting drawing file provided by the customer and parse out the geometric coordinate sequence (x) of the trajectory to be cut. i ,y i ); S22: Register the cutting trajectory coordinates with the plate thickness distribution map in spatial coordinates to determine the translation and rotation matrices between the coordinate systems; S23: Extract the actual plate thickness T corresponding to each cutting trajectory point. i =T(x i ,y i ), generate the plate thickness variation curve T(s) along the cutting path, where s is the cumulative arc length of the cutting path.

[0017] Step S4 includes: S41: Calculate the target gas pressure P based on the plate thickness variation curve T(s) and the gas pressure calculation model. The gas pressure calculation model includes: 1) Laser cutting mode: P=P0+k1(T-T0), where T0=5mm, P0=0.8bar and k1=0.06 for oxygen cutting, and P0=1.0bar and k1=0.03 for nitrogen cutting; 2) Flame cutting mode: Cutting speed V=0.45T -0.45 Main oxygen pressure The upper limit of the main oxygen pressure is 7.0 bar, and the combustible gas pressure is P. gas =1.05 bar, auxiliary oxygen pressure ; 3) Composite cutting mode: ,in, The P value is calculated using the laser cutting mode formula in 1) above; The result is calculated using the flame cutting mode formula in section 2) above. value, ; For the transition section, the following applies: 4) Gas pressure transition formula:

[0018] 5) Cutting speed transition formula: ; S42: According to the formula Calculate the gas pressure at each location in the transition zone. ; Among them, P start and P end Based on the initial thickness T start and termination thickness T end The target pressure value P is calculated using the pressure calculation model in step S41. The two endpoints of the value are T(s), which is the plate thickness variation curve. S43: According to the formula Calculate the cutting speed at each position in the transition zone. ; Where: V start The cutting speed corresponding to the initial thickness; The speed decay index, ranging from 0.3 to 0.6, reflects the nonlinear decrease in cutting speed as plate thickness increases; S5: Through the process parameter sequence generation unit, the calculation results are generated into a process parameter sequence containing the cutting mode, gas pressure, cutting speed, and focal position corresponding to the cutting trajectory points, and preloaded into the execution buffer of the CNC system.

[0019] Step S6 includes: S61: The software-defined pneumatic logic interlock is executed through the interlock logic matrix in the CNC system to ensure that only one cutting mode is activated at any given time. S62: Real-time monitoring of cutting head spacing, gas pressure, and cutting area temperature via sensor network. When the monitored parameters reach preset thresholds, a graded warning is issued and automatic switching of cutting modes is prohibited, keeping the equipment status pending manual confirmation. S63: Emergency response is performed through a hardware safety loop independent of the CNC system. When the CNC system heartbeat signal is lost, all gas valves and laser power are automatically cut off. When the pressure inside the cutting head cavity exceeds the burst threshold, pressure is released through a rupture disc.

[0020] The beneficial effects of this invention are: 1. This invention improves the cutting quality of variable thickness plates: By pre-scanning the thickness and mapping the path before cutting, the thickness change curve along the cutting trajectory is accurately obtained. Combined with the progressive process switching algorithm in the transition zone, the smooth change of process parameters is realized, the cutting defect problem at the abrupt change in thickness is solved, and the consistency of the cut surface quality is improved.

[0021] 2. This invention reduces operational difficulty and reliance on manual labor: it eliminates the need for manual thickness measurement, manual switching of cutting modes, and manual planning of transition zone processes, achieving full automation from plate scanning to process parameter generation, thus reducing the skill requirements for operators.

[0022] 3. This invention enhances equipment safety: Through a three-level progressive safety architecture of software logic interlocking, graded early warning and manual confirmation, and independent hardware safety loop, it achieves comprehensive safety monitoring of composite equipment where laser and gas coexist, effectively preventing safety accidents caused by misoperation, equipment failure and abnormal operating conditions.

[0023] 4. This invention improves processing efficiency: The pre-planning mechanism for process parameters avoids the response lag of real-time feedback, and the cutting process is continuous and smooth; at the same time, by scanning the next plate while cutting the previous plate, pre-scanning and cutting can be performed in parallel, which improves equipment utilization. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0025] In the figure, 1. Cutting head body, 2. Z-axis unit, 3. Gantry beam unit, 4. Cutting table unit, 5. Bed unit, 6. Displacement sensor. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments.

[0027] Example 1 Combination Figure 1A laser flame composite cutting device for sheet metal includes a cutting head body 1, a Z-axis unit 2, a gantry beam unit 3, a cutting table unit 4, a bed unit 5, and a CNC system. The cutting head body 1, Z-axis unit 2, and gantry beam unit 3 are electrically connected to the CNC system. The cutting head body 1 is rigidly fixed to the Z-axis unit 2 by bolts and can move up and down in the Z-axis direction via a Z-axis sliding plate. The Z-axis unit 2 is fixed to the gantry beam unit 3 via linear guides and can move left and right in the Y-axis direction via linear guides. The gantry beam unit 3 is fixed to the bed unit 5 via linear guides and can move forward and backward in the X-axis direction via linear guides. The cutting table unit 4 is independent of the above-mentioned units and is placed on the ground together with the bed unit 5. The device also includes a follow-up thickness measurement unit, a cutting path sheet thickness mapping module, an adaptive process pre-planning module, and a multi-level safety control logic unit. The follow-up thickness measurement unit, cutting path sheet thickness mapping module, adaptive process pre-planning module, and multi-level safety control logic unit are electrically connected to the CNC system. The follow-up thickness measurement unit is used to perform plate thickness scanning before cutting and generate a two-dimensional plate thickness distribution map. The follow-up thickness measurement unit includes a displacement sensor 6 installed on the cutting head body. The displacement sensor is connected to the CNC system. The displacement sensor 6 is a high-precision displacement sensor, which is bolted to the cutting head body 1. The cutting path plate thickness mapping module is used to register the trajectory coordinates of the customer's cutting drawing with the plate thickness distribution map in spatial coordinates, and generate a plate thickness variation curve along the cutting path; The adaptive process pre-planning module is used to complete the process segment division, transition zone parameter interpolation, and process parameter sequence calculation before cutting based on the plate thickness variation curve. The multi-level safety control logic unit is used to implement a three-level progressive safety control system, including software-defined gas path logic interlocking, graded early warning and manual confirmation, and independent hardware safety loops.

[0028] The displacement sensor is either a capacitive displacement sensor or a laser triangulation distance sensor.

[0029] The adaptive process pre-planning module includes: Process section division unit: Based on the plate thickness variation curve, the cutting path is divided into a constant thickness section and a transition section, where the transition section refers to the section where the plate thickness variation exceeds a preset threshold T. max The area; Gas pressure calculation unit: Embedded gas pressure calculation model based on plate thickness; Process parameter sequence generation unit: Generates the calculation results into a process parameter sequence containing the cutting mode, gas pressure, cutting speed, and focal position corresponding to the cutting trajectory points, and preloads it into the execution buffer of the CNC system.

[0030] The multi-level security control logic unit includes: Logic interlock layer: The software-defined gas path logic interlock is implemented by the interlock logic matrix built into the CNC system. The interlock logic matrix includes laser-gas interlock, ignition-gas supply timing interlock and mode exclusive lock, and does not rely on the mechanical switch of the physical protective cover. Real-time monitoring layer: Includes pressure sensor, displacement sensor and temperature sensor. When the monitored parameters reach the preset threshold, it will issue a graded warning and prevent automatic switching of cutting mode in fault condition, and keep the equipment status pending manual confirmation. Emergency response layer: includes a hardware safety loop independent of the CNC system. The hardware safety loop includes a watchdog timer, a redundant shut-off actuator consisting of a normally closed solenoid valve and a manual shut-off valve connected in series, and a rupture disc pressure relief device located inside the cutting head.

[0031] The tiered early warning system of the real-time monitoring layer includes: Level 1 warning: When the distance between the cutting head and the material is less than the safe distance D safe At this time, the feed speed is reduced and the cutting head is not automatically raised; Level 2 warning: When the gas pressure is lower than the lower limit threshold, the feeding motion is suspended, the gas purging state is maintained, an audible and visual alarm is issued, and manual confirmation is required. Level 3 warning: When the temperature of the cutting area exceeds the upper limit threshold, stop the cutting action, continue purging, issue an audible and visual alarm, and resume after manual reset; Emergency Warning: When a backfire signal is detected, the main gas valve will be shut off within 0.1 seconds, nitrogen purging will be initiated, and emergency procedures will be executed.

[0032] Example 2 A cutting method using a laser-flame composite cutting device, comprising the following steps: S1: Before the cutting program starts, the CNC system controls the drive mechanism to move the cutting head along the preset scanning path, and the sensor measures the Z-axis displacement Z of the cutting head relative to the reference plane of the cutting table in real time. real (x,y), the CNC system uses the formula T(x,y=Z base -Z real (x,y) Calculates the actual thickness T(x,y) of the plate at the coordinate point (x,y), where Z base The calibrated height of the cutting head from the reference plane of the cutting table under no-load conditions is used to generate a two-dimensional plate thickness distribution map after scanning; specifically including: 1.1 Scanning path planning: The CNC system automatically generates an arc-shaped scanning path or an edge contour scanning path based on the size range of the material to be processed, ensuring that the scan covers the entire surface of the material and the processing area corresponding to the cutting drawing.

[0033] 1.2 Z-axis displacement measurement: The drive mechanism moves the cutting head along the scanning path, and the sensor measures the Z-axis displacement Z of the cutting head relative to the cutting table reference plane in real time. real (x, y), where (x, y) are the planar coordinates of the cutting head in the coordinate system of the cutting table.

[0034] 1.3 Thickness Calculation: The CNC system calculates thickness using the formula T(x, y) = Z. base - Z real (x, y) calculates the actual thickness of the sheet metal at the coordinate point (x, y), where Z... base This refers to the pre-calibrated standard height of the cutting head from the reference plane of the cutting table under no-load conditions.

[0035] 1.4 Plate Thickness Distribution Map Generation: After scanning, the CNC system stores the thickness data of all sampling points into a two-dimensional matrix to generate a plate thickness distribution map. This distribution map can intuitively display the thickness changes in various regions of the plate, including uniform thickness regions, gradually changing thickness regions, and locally thickened regions (such as reinforcing ribs, weld scars, etc.).

[0036] Technical benefits: Unlike the real-time measurement method in the existing technology during the cutting process, the pre-scanning mechanism of the present invention has acquired complete thickness distribution data of the plate before cutting, providing a complete information basis for subsequent process pre-planning and avoiding the response lag problem of the real-time feedback mechanism.

[0037] S2: Import the customer's cutting drawing, register the cutting trajectory coordinates with the plate thickness distribution map in spatial coordinates, and generate the plate thickness variation curve T(s) along the cutting path; specifically including: Perform the following operations using the cutting path plate thickness mapping module: 2.1 Import and Parsing of Cutting Drawings: The module imports the cutting drawing files provided by the customer. The file formats include, but are not limited to, DXF and DWG formats. It parses out the geometric coordinate sequence (x_i, y_i) of the trajectory to be cut, as well as the connection relationship and cutting order between the trajectories.

[0038] 2.2 Spatial Coordinate Registration: The cutting trajectory coordinates are registered with the plate thickness distribution map generated in step 1. The registration process includes: 1) determining the translation and rotation matrices between the plate thickness distribution map coordinate system and the cutting drawing coordinate system; 2) interpolating the thickness distribution map to match its resolution with the density of the cutting trajectory points.

[0039] 2.3 Path Thickness Correlation: Extract the actual plate thickness value T_i = T(x_i, y_i) corresponding to each cutting trajectory point (x_i, y_i), and generate a cutting path-plate thickness correlation graph, i.e., the plate thickness variation curve T(s) along the cutting path, where s is the cumulative arc length of the cutting path, defined as... .

[0040] Technical effect: By spatially mapping the customer's cutting drawings with the measured plate thickness distribution map, the present invention achieves a precise correlation between the cutting path and the plate thickness information, providing a data basis for the planning of process parameters along the path. This is a key feature not disclosed in the prior art.

[0041] S3: Divide the plate thickness into constant thickness and transition sections based on the plate thickness variation curve T(s). The transition section refers to the plate thickness variation exceeding a preset threshold T. max The area; S4: For the transition section, a progressive process switching algorithm is used to calculate the process parameters for each cutting point, including: S41: Calculate the target gas pressure P based on the plate thickness variation curve T(s) and the gas pressure calculation model. The gas pressure calculation model includes: 1) Laser cutting mode: P=P0+k1(T-T0), where T0=5mm, P0=0.8bar and k1=0.06 for oxygen cutting, and P0=1.0bar and k1=0.03 for nitrogen cutting; 2) Flame cutting mode: Cutting speed V=0.45T -0.45 Main oxygen pressure The upper limit of the main oxygen pressure is 7.0 bar, and the combustible gas pressure is P. gas =1.05 bar, auxiliary oxygen pressure ; 3) Composite cutting mode: ,in, The P value is calculated using the laser cutting mode formula in 1) above; The result is calculated using the flame cutting mode formula in section 2) above. value, ; For the transition section, the following applies: 4) Gas pressure transition formula:

[0042] 5) Cutting speed transition formula: .

[0043] S42: According to the formula Calculate the gas pressure at each location in the transition zone. ; Among them, P startand P end Based on the initial thickness T start and termination thickness T end The target pressure value P is calculated by the pressure calculation model described in step S41, and T(s) is the plate thickness variation curve. S43: According to the formula Calculate the cutting speed at each position in the transition zone. ; Wherein: V start The cutting speed corresponding to the initial thickness; The speed decay index, ranging from 0.3 to 0.6, reflects the non-linear decrease in cutting speed as plate thickness increases.

[0044] S5: Through the process parameter sequence generation unit, the calculation results are generated into a process parameter sequence containing the cutting mode, gas pressure, cutting speed, and focal position corresponding to the cutting trajectory points, and preloaded into the execution buffer of the CNC system; Specifically, through the adaptive process pre-planning module, the CNC system pre-plans the process parameters based on the plate thickness variation curve T(s) along the cutting path before executing the cutting action. This includes three sub-steps: process segment division, transition zone parameter interpolation, and process parameter sequence generation. 1) Division of process sections The system automatically divides the cutting path into several segments based on the plate thickness variation curve: Constant thickness section: Plate thickness fluctuation is less than the preset threshold T max (T) max For regions with a value range of 0.5mm to 2mm, stable process parameters corresponding to this thickness are used, and no adjustments are required within the section.

[0045] Transition zone: The area where the plate thickness change exceeds a preset threshold. The system identifies the starting point s of the transition zone. start and the endpoint s end and the corresponding initial thickness T start and termination thickness T end The transition zone is further divided into a thickness-increasing zone and a thickness-decreasing zone, each employing different parameter variation strategies.

[0046] 2) Calculation model of gas pressure and cutting speed based on plate thickness The CNC system has a pre-set thickness-process dynamic matching model, which is obtained by fitting a large amount of process test data, and specifically includes: (1) Laser cutting mode (T ≤ T1, where T1 = 30mm), the formula for calculating the auxiliary gas pressure P is: P = P0 + k1(T - T0) Wherein: Oxygen cutting: P0 = 0.8 bar, k1 = 0.06, T0 = 5 mm; Nitrogen cutting: P0 = 1.0 bar, k1 = 0.03, T0 = 5 mm.

[0047] (2) Flame cutting mode (T ≤ T2, where T2 = 50mm) Based on measured data (plate thickness 50mm~200mm), the following functional relationship was obtained by fitting:

[0048] The coefficients of the above formula are obtained by least squares fitting, and the goodness of fit R0 is... 2 >0.98.

[0049] (3) Composite cutting mode (T_1) <T<T_2) The pressure of the mixed gas was calculated using a weighted fusion algorithm of laser and flame: P mix =λP laser (T)+(1-λ)P flame (T) Where the fusion coefficient λ = = P flame (T) Calculated according to the flame mode formula.

[0050] 3) Gradual process switching algorithm in the transition zone For the transition section identified in step 3.1, the system adopts a progressive process switching algorithm to avoid cutting defects caused by sudden process changes: (1) Gas pressure transition formula: P(s) = P start + (T(s) - T start ) Where P start and P end Based on the initial thickness T start and termination thickness T end The target pressure value is calculated using the pressure model described in step 3.2.

[0051] (2) Cutting speed transition formula: V(s) = V start

[0052] Where: V start The cutting speed corresponding to the initial thickness; The speed decay index, ranging from 0.3 to 0.6, reflects the non-linear decrease in cutting speed as plate thickness increases.

[0053] (3) Mode switching transition processing: When the transition zone crosses the mode switching threshold (i.e., T) start With T end When the thickness ranges of different cutting modes are located, the system sets up a mixed mode section in the transition zone: near the thin plate side (thickness close to the T1 region), laser cutting is the main method, with flame-assisted preheating; near the thick plate side (thickness close to the T2 region), flame cutting is the main method, with laser-assisted perforation; the laser power and gas flow rate work together in a linear interpolation ratio according to the plate thickness.

[0054] 4) Generation of process parameter sequences The system generates a sequence of cutting process parameters from the above calculation results. This sequence contains the following parameters for each cutting trajectory point: Cutting mode identifier (laser / flame / composite); laser power (laser and composite modes only); auxiliary gas pressure (laser mode) or cutting oxygen pressure and fuel gas pressure (flame mode); cutting speed; focal point position (laser and composite modes only); nozzle height.

[0055] The sequence of process parameters is preloaded into the execution buffer of the CNC system, waiting for the cutting to be executed.

[0056] Technical benefits: Unlike existing technologies that rely on real-time feedback and passive adjustment, the pre-planning mechanism of this invention completes the calculation and optimization of all process parameters before cutting, and executes them sequentially during the cutting process without any response lag. The gradual switching algorithm in the transition zone ensures smooth changes in process parameters, solving the cutting quality problem at locations of abrupt thickness changes.

[0057] S6: Execute the cutting operation according to the pre-planned sequence of process parameters. Specifically: Through multi-level security control logic units, a three-level progressive security architecture is adopted, including a logic interlocking layer, a real-time monitoring layer, and an emergency response layer. Each layer operates independently and serves as a backup for the others, and the following operations are performed: 1) Logic Interlock Layer – Software-defined gas path logic interlock This equipment uses software-defined pneumatic logic interlocks, eliminating the need for mechanical switches with physical protective covers. It achieves this through an interlock logic matrix built into the CNC system.

[0058] The difference between this invention and the prior art: The prior art disclosed in EP3756817B1 protects physical protective shields and mechanical interlock switches, while the logic interlock layer of this invention is implemented entirely by software and does not depend on any physical protective shield structure. The implementation method and technical path are completely different.

[0059] 2) Real-time monitoring layer – tiered early warning and manual confirmation mechanism A multi-dimensional sensor network is set up, employing a tiered early warning + manual confirmation strategy, and explicitly prohibiting the use of a strategy that "automatically switches to a cutting mode in case of failure" (this strategy is already covered by CN119187885A):

[0060] Distinguishing from existing technologies: The existing technology disclosed in patent document CN119187885A adopts the strategy of "automatic switching of cutting mode in case of failure" (such as automatically switching to flame mode to maintain production when the laser fails). This invention adopts a graded early warning + manual confirmation strategy, emphasizing "safety first over continuous production". In case of failure, it does not automatically switch modes, but keeps the equipment in a safe state and waits for manual intervention to avoid secondary accidents caused by automatic switching.

[0061] 3) Emergency Response Layer – Independent Hardware Security Loop This invention establishes a hardware safety loop independent of the CNC system as backup protection for software logic interlocks: i) Hardware watchdog timer: An independent hardware watchdog circuit is set up. The CNC system needs to periodically (period ≤ 100ms) send a heartbeat signal to the watchdog. If the watchdog does not receive a heartbeat signal within 100ms (indicating that the CNC system has crashed or the program has malfunctioned), the hardware circuit will automatically cut off the power supply to all air valves and the laser, putting the equipment into a safe shutdown state. ii) Redundant shut-off actuator: The gas supply pipeline adopts a series configuration of a normally closed solenoid valve and a manual shut-off valve. The normally closed solenoid valve automatically closes when power is lost and is controlled by both the CNC system and the watchdog circuit; the manual shut-off valve serves as the final physical isolation measure, allowing the operator to manually shut off the gas supply even if the control system completely fails. iii) Rupture disc pressure relief device: A rupture disc pressure relief port is installed inside the cutting head, and the rupture disc activation pressure is set to 1.2 MPa. When the pressure inside the cutting head exceeds 1.2 MPa due to abnormal combustion or gas circuit failure, the rupture disc will automatically rupture and relieve pressure, preventing explosion damage to the main body of the equipment and injury to the operators.

[0062] Technical effect: The safety control logic of this invention achieves triple safety protection of "software logic interlock + hierarchical early warning and handling + hardware redundancy cut-off", which is clearly technically different from the "physical protective shield interlock" and "automatic fault switching mode" of the prior art, and significantly improves the safety level of the equipment.

[0063] Step S2 includes: S21: Import the cutting drawing file provided by the customer and parse out the geometric coordinate sequence (x) of the trajectory to be cut. i ,y i ); S22: Register the cutting trajectory coordinates with the plate thickness distribution map in spatial coordinates to determine the translation and rotation matrices between the coordinate systems; S23: Extract the actual plate thickness T corresponding to each cutting trajectory point. i =T(x i ,y i ), generate the plate thickness variation curve T(s) along the cutting path, where s is the cumulative arc length of the cutting path; Step S6 includes: S61: The software-defined pneumatic logic interlock is executed through the interlock logic matrix in the CNC system to ensure that only one cutting mode is activated at any given time. S62: Real-time monitoring of cutting head spacing, gas pressure, and cutting area temperature via sensor network. When the monitored parameters reach preset thresholds, a graded warning is issued and automatic switching of cutting modes is prohibited, keeping the equipment status pending manual confirmation. S63: Emergency response is performed through a hardware safety loop independent of the CNC system. When the CNC system heartbeat signal is lost, all gas valves and laser power are automatically cut off. When the pressure inside the cutting head cavity exceeds the burst threshold, pressure is released through a rupture disc.

[0064] Example 3 This embodiment uses the cutting of variable thickness ship steel plates as an example to illustrate the cutting method. The plate to be cut is high-strength ship hull structural steel, grade AH36.

[0065] 1. Experimental conditions In this embodiment, the nominal thickness of the sheet material is 20mm, but the actual thickness varies as follows: Thickness of the main body area: 19.5mm~20.5mm (uniform area); Thickness of the reinforcing rib area: 25mm~26mm within the coordinate range of (300mm, 400mm) to (350mm, 450mm); There is a thickness gradient transition zone at the edge of the board, with a width of about 80mm and a thickness that gradually changes from 12mm to 20mm.

[0066] The customer's cutting drawing is a fan-shaped outline, with a total cutting path length of approximately 1850mm. This path passes precisely through the reinforcing rib area and the edge gradient zone.

[0067] 2. Pre-scanning before cutting The follow-up thickness measurement unit is activated, and the cutting head scans the entire sheet material in an arc-shaped pattern, with the sheet size being 1500mm × 1000mm and the scanning interval set to 20mm. The capacitive displacement sensor has a sampling frequency of 100Hz and records the Z-axis displacement of each sampling point.

[0068] According to the formula T(x,y = Z) base - Z real(x,y) Calculate the thickness and generate a two-dimensional plate thickness distribution map. The distribution map shows that the average thickness in the main body area is 20.1 mm, and the standard deviation is 0.3 mm; the maximum thickness in the rib area is 25.8 mm; the thickness in the edge gradient zone increases linearly from 12.2 mm to 20.3 mm.

[0069] 3. Cutting path mapping and plate thickness correlation Import the fan-shaped cutting drawing (DXF format), parse out the sequence of cutting trajectory points, a total of 1580 trajectory points. After spatial coordinate registration (rotation angle 3.5°, translation vector (25 mm, -12 mm)), extract the plate thickness value corresponding to each trajectory point and generate the plate thickness change curve T(s) along the cutting path.

[0070] The curve shows that in the arc length range from s = 720 mm to s = 815 mm, the thickness increases from 20.1 mm to 25.6 mm and then drops back to 20.3 mm, forming two transition sections; in the range from s = 1420 mm to s = 1500 mm, the thickness drops from 20.2 mm to 12.5 mm, forming a thickness decreasing transition section.

[0071] 4. Process pre-planning The system presets the thresholds T1 = 30 mm (upper limit of laser cutting), T2 = 50 mm (lower limit of flame cutting). Since the main body thickness of 20.1 mm satisfies T1 < T < T2, it is determined to be a composite cutting mode; the thickness of 25.8 mm in the rib area is also within the composite mode range; the thickness of 12.5 mm in the edge gradient zone satisfies T < T1, and it is determined to be a laser cutting mode.

[0072] According to the pressure calculation formula: Gas pressure in the composite mode: P mix = λP laser (T)+(1 - λ)P flame (T), where λ = = ; Laser mode pressure (nitrogen assisted): P = 1.0 + 0.03(T - 5) (MPa); Main oxygen pressure in the flame mode: P O2 = 3.5 + 2.2log 10 ( ) (bar); Fuel gas pressure in the flame mode: P gas = 1.05 (bar); Auxiliary oxygen pressure in the flame mode: P aux = 1.40 - 0.0012(T - 50) (bar); The transition zone adopts a progressive switching algorithm, and the speed decay exponent = 0.45.

[0073] The system generates a complete sequence of process parameters, including target parameters for 1580 trajectory points.

[0074] 5. Cutting Execution and Results The CNC system executes the cutting according to the pre-planned parameters. After cutting, the following checks are performed: The cut surface of the fan-shaped profile in the area of ​​varying thickness is uniformly flat, with no slag or incomplete cutting. There are no obvious tool marks or cutting defects caused by sudden changes in process in the transition zone (thickness change area); The cut width in the reinforcing rib area is uniform, and the cross-sectional roughness R is [missing information]. a ≤12.5 m.

[0075] 6. Comparative Experiment To verify the technical effect of this invention, a comparative device (with only real-time feedback adjustment function) was used to cut the same batch of boards. Comparative test results: At the point of abrupt change in thickness (edge ​​of the reinforcing rib), due to the sensor response lag (approximately 50ms), the cutting quality suffers from brief overheating and uneven cut. At the edge gradient zone, the real-time feedback adjustment failed to predict the thickness change trend in advance, the cutting speed adjustment was lagging, and local slag buildup occurred.

[0076] Comparative experiments have demonstrated that the pre-planning method of this invention has significant technical advantages in cutting plates of varying thickness.

[0077] Example 4 Verification of process parameters for thick plate flame cutting: 1. Experimental conditions The equipment of this invention is used to cut carbon steel plates with thicknesses of 50mm, 70mm, 100mm, 120mm, 140mm, 150mm, 180mm, and 200mm. The system automatically calls the flame cutting mode and calculates the process parameters according to the above-mentioned fitting formula.

[0078] 2. Comparison of calculated and measured process parameters

[0079] 3. Cutting quality All plates of various thicknesses exhibited smooth cut surfaces after cutting, with no slag residue or incomplete cuts. Compared to a control group using fixed process parameters, the adaptive formula of this invention significantly improved the consistency of cut surface quality in thick plate cutting.

[0080] Example 5 Verification of security control logic: 1. Laser-gas interlock verification During operation in flame cutting mode, a laser activation command was manually sent via the host computer software. The CNC system, executing the interlock logic matrix, detected that the gas valve was open, refused to output the laser enable signal, and displayed an alarm message: "Operational conflict: Laser and gas cannot be turned on simultaneously." No unexpected laser emission occurred.

[0081] 2. Level II Early Warning Verification During flame cutting, the gas supply valve was manually shut off. The gas pressure sensor detected a pressure drop from 0.12 MPa to 0.04 MPa (below the lower threshold of 0.05 MPa). The system triggered a level-two warning. The cutting feed motion is immediately paused; the preheating oxygen and gas valves remain open (continuous purging); the human-machine interface displays the alarm message "Insufficient gas pressure, please check the gas source"; the cutting head remains in place and does not automatically reset or switch modes.

[0082] After the operator reopens the gas supply valve, they can click the "Reset" button on the human-machine interface to restore the equipment to normal operation and resume cutting.

[0083] 3. Watchdog circuit verification During the cutting process, the communication cable between the CNC system and the hardware safety circuit is manually disconnected. If the watchdog timer does not receive a heartbeat signal within 100ms, the hardware circuit automatically cuts off power to all air valves and the laser. The flame cutting gas valve is closed; the laser power supply is cut off; the equipment enters a safe shutdown state.

[0084] Even when the simulated CNC system malfunctions, the equipment can still be safely shut down without any dangerous situations such as the air valve failing to close or the laser continuing to output.

[0085] 4. Rupture disc pressure relief verification A gas path blockage was created inside the cutting head, causing the internal pressure to rise to 1.2 MPa, at which point the rupture disc ruptured and released the pressure. The cutting head housing did not experience an explosive rupture, and the operator was not injured. After the rupture disc ruptured, the equipment automatically shut down; operation can only resume after the rupture disc is replaced.

[0086] In the description of this invention, the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "vertical," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only to describe the invention and not to require the invention to be constructed or operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected" and "linked" in this invention should be interpreted broadly. For example, they can refer to a connection or a detachable connection; they can refer to a direct connection or an indirect connection through intermediate components. Those skilled in the art can understand the specific meaning of the above terms based on the specific circumstances.

[0087] The above description represents preferred embodiments of the present invention. The specific embodiments are provided solely for a better understanding of the invention's concept. Those skilled in the art will recognize that various improvements or equivalent substitutions can be made based on the principles of the present invention, and these improvements or equivalent substitutions are also considered to fall within the scope of protection of the present invention.

Claims

1. A laser-flame composite cutting device for sheet metal, comprising a cutting head body, a Z-axis unit, a gantry beam unit, a cutting table unit, a bed unit, and a CNC system, wherein the cutting head body, Z-axis unit, and gantry beam unit are electrically connected to the CNC system, and the cutting head body is connected to the Z-axis unit; the Z-axis unit achieves left-right movement in the Y-axis direction via linear guides; the gantry beam unit achieves forward-backward movement in the X-axis direction via linear guides, characterized in that... It also includes a follow-up thickness measurement unit, an adaptive process pre-planning module, and a multi-level safety control logic unit. The follow-up thickness measurement unit, the adaptive process pre-planning module, and the multi-level safety control logic unit are electrically connected to the CNC system, wherein: The follow-up thickness measurement unit is used to perform plate thickness scanning before cutting and generate a two-dimensional plate thickness distribution map. The follow-up thickness measurement unit includes a displacement sensor installed on the cutting head body, and the displacement sensor is connected to the CNC system. The adaptive process pre-planning module is used to complete the process segmentation, transition zone parameter interpolation, and process parameter sequence calculation before cutting based on the scanned thickness data. The multi-level safety control logic unit is used to implement a three-level progressive safety control system, including software-defined gas circuit logic interlock, graded early warning and manual confirmation, and independent hardware safety loops. The independent hardware safety loops are mounted on the oxygen gas circuit and the gas gas circuit to control the opening and closing of the gas circuit, and are mounted on the laser to control the opening and closing of the light shutter. The independent hardware is electrically connected to the system.

2. The laser-flame composite cutting equipment for sheet metal according to claim 1, characterized in that, The displacement sensor is either a capacitive displacement sensor or a laser triangulation distance sensor.

3. The laser-flame composite cutting equipment for sheet metal according to claim 1, characterized in that, The adaptive process pre-planning module includes: Process section division unit: Based on the plate thickness variation curve, the cutting path is divided into a constant thickness section and a transition section, where the transition section refers to the section where the plate thickness variation exceeds a preset threshold T. max The area; Gas pressure calculation unit: Embedded gas pressure calculation model based on plate thickness; Process parameter sequence generation unit: Generates the calculation results into a process parameter sequence containing the cutting mode, gas pressure, cutting speed, and focal position corresponding to the cutting trajectory points, and preloads it into the execution buffer of the CNC system.

4. The laser-flame composite cutting equipment for sheet metal according to claim 3, characterized in that, The multi-level security control logic unit includes: Logic interlock layer: The software-defined gas path logic interlock is implemented by the interlock logic matrix built into the CNC system. The interlock logic matrix includes laser-gas interlock, ignition-gas supply timing interlock and mode exclusive lock, and does not rely on the mechanical switch of the physical protective cover. Real-time monitoring layer: Includes pressure sensor, displacement sensor and temperature sensor. When the monitored parameters reach the preset threshold, it will issue a graded warning and prevent automatic switching of cutting mode in fault condition, and keep the equipment status pending manual confirmation. Emergency response layer: includes a hardware safety loop independent of the CNC system. The hardware safety loop includes a watchdog timer, a redundant shut-off actuator consisting of a normally closed solenoid valve and a manual shut-off valve connected in series, and a rupture disc pressure relief device located inside the cutting head.

5. The laser-flame composite cutting equipment for sheet metal according to claim 4, characterized in that, The tiered early warning system of the real-time monitoring layer includes: Level 1 warning: When the distance between the cutting head and the material is less than the safe distance D safe At this time, the feed speed is reduced and the cutting head is not automatically raised; Level 2 warning: When the gas pressure is lower than the lower limit threshold, the feeding motion is suspended, the gas purging state is maintained, an audible and visual alarm is issued, and manual confirmation is required. Level 3 warning: When the temperature of the cutting area exceeds the upper limit threshold, stop the cutting action, continue purging, issue an audible and visual alarm, and resume after manual reset; Emergency Warning: When a backfire signal is detected, the main gas valve will be shut off within 0.1 seconds, nitrogen purging will be initiated, and emergency procedures will be executed.

6. A cutting method using a laser-flame composite cutting device for sheet metal, characterized in that, The laser-flame composite cutting device according to claim 5 includes the following steps: S1: Before the cutting program starts, the CNC system controls the drive mechanism to move the cutting head along the preset scanning path, and the sensor measures the Z-axis displacement Z of the cutting head relative to the reference plane of the cutting table in real time. real (x,y), the CNC system uses the formula T(x,y=Z base -Z real (x,y) Calculates the actual thickness T(x,y) of the plate at the coordinate point (x,y), where Z base The calibrated height of the cutting head from the reference plane of the cutting table under no-load conditions is used to generate a two-dimensional plate thickness distribution map after scanning. S2: Import the customer's cutting drawing, register the cutting trajectory coordinates with the plate thickness distribution map in spatial coordinates, and generate the plate thickness variation curve T(s) along the cutting path; S3: Divide the plate thickness into constant thickness and transition sections based on the plate thickness variation curve T(s). The transition section refers to the plate thickness variation exceeding a preset threshold T. max The area; S4: For the transition section, a progressive process switching algorithm is used to calculate the process parameters of each cutting point; S5: Through the process parameter sequence generation unit, the calculation results are generated into a process parameter sequence containing the cutting mode, gas pressure, cutting speed, and focal position corresponding to the cutting trajectory points, and preloaded into the execution buffer of the CNC system; S6: Perform the cutting operation according to the pre-planned sequence of process parameters.

7. The cutting method using a laser-flame composite cutting device for sheet metal according to claim 6, characterized in that, Step S2 includes: S21: Import the cutting drawing file provided by the customer and parse out the geometric coordinate sequence (x) of the trajectory to be cut. i ,y i ); S22: Register the cutting trajectory coordinates with the plate thickness distribution map in spatial coordinates to determine the translation and rotation matrices between the coordinate systems; S23: Extract the actual plate thickness T corresponding to each cutting trajectory point. i =T(x i ,y i ), generate the plate thickness variation curve T(s) along the cutting path, where s is the cumulative arc length of the cutting path.

8. The cutting method using a laser-flame composite cutting device for sheet metal as described in claim 6, characterized in that, Step S4 includes: S41: Based on the plate thickness variation curve T(s), calculate the target gas pressure P according to the gas pressure calculation model. The gas pressure calculation model includes: 1) Laser cutting mode: P = P0 + k1(T - T0), where T0 = 5 mm, P0 = 0.8 bar and k1 = 0.06 for oxygen cutting, and P0 = 1.0 bar and k1 = 0.03 for nitrogen cutting; 2) Flame Cutting Mode: Cutting speed V=0.45T -0.45 Main oxygen pressure The upper limit of the main oxygen pressure is 7.0 bar, and the combustible gas pressure is P. gas =1.05 bar, auxiliary oxygen pressure ; 3) Composite cutting mode: ,in, The P value is calculated using the laser cutting mode formula in 1) above; The result is calculated using the flame cutting mode formula in section 2) above. value, ; For the transition section, the following applies: 4) Gas pressure transition formula: 5) Cutting speed transition formula: ； S42: According to the formula Calculate the gas pressure at each location in the transition zone. ; Among them, P start and P end Based on the initial thickness T start and termination thickness T end The target pressure value P is calculated using the pressure calculation model in step S41. The two endpoints of the value are T(s), which is the plate thickness variation curve. S43: According to the formula Calculate the cutting speed at each position in the transition zone. ; Where: V start The cutting speed corresponding to the initial thickness; The speed decay index, ranging from 0.3 to 0.6, reflects the non-linear decrease in cutting speed as plate thickness increases.

9. The cutting method using a laser-flame composite cutting device for sheet metal as described in claim 6, characterized in that, Step S6 includes: S61: The software-defined pneumatic logic interlock is executed through the interlock logic matrix in the CNC system to ensure that only one cutting mode is activated at any given time. S62: Real-time monitoring of cutting head spacing, gas pressure, and cutting area temperature via sensor network. When the monitored parameters reach preset thresholds, a graded warning is issued and automatic switching of cutting modes is prohibited, keeping the equipment status pending manual confirmation. S63: Emergency response is performed through a hardware safety loop independent of the CNC system. When the CNC system heartbeat signal is lost, all gas valves and laser power are automatically cut off. When the pressure inside the cutting head cavity exceeds the burst threshold, pressure is released through a rupture disc.

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