Laser cutting machine

Abstract

The invention provides a laser cutting machine, and relates to the technical field of laser cutting. The laser cutting machine comprises a beam expander, a focus control module, a cutting head main body and a laser beam outlet, the focus control module comprises a laser displacement sensor, an MEMS micromirror array, an FPGA controller and a focusing optical module. The laser displacement sensor is used for scanning the surface of the cut object at a preset length in front of the moving direction of the laser focus so as to obtain surface height information; the MEMS micromirror array is used for controlling the direction of the laser beam entering the focusing optical module; the focusing optical module is used for focusing the laser beam to a working surface corresponding to a cut object; and the FPGA controller is used for generating a first driving signal of the MEMS micromirror array according to the surface height information so as to drive the MEMS micromirror array to finely adjust the laser focus position. According to the laser cutting machine, high-precision compensation of the focus position is achieved, cutting seam width fluctuation is reduced, and cutting precision and stability are improved.

Description

Technical Field

[0001] The present disclosure relates to the field of laser cutting technology, and in particular to a laser cutting machine. Background Art

[0002] Laser cutting machines mainly use high-power density laser beams to irradiate materials, causing them to quickly melt, vaporize or reach the ignition point, and use high-speed airflow to blow away the molten material to achieve cutting. With the development of laser cutting technology, laser cutting applications are becoming more and more common in power batteries, aerospace and other fields, but the requirements for the accuracy and stability of laser cutting machines are also getting higher and higher.

[0003] How to improve the cutting accuracy and stability of laser cutting machines is a technical problem that needs to be solved urgently.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] The present disclosure provides a laser cutting machine, at least providing a laser cutting machine with higher precision and stability.

[0006] Other features and advantages of the present disclosure will become apparent from the following detailed description, or may be learned in part by the practice of the present disclosure.

[0007] According to one aspect of the present disclosure, a laser cutting machine is provided, comprising: a beam expander, a focus control module, a cutting head body and a laser beam outlet; the focus control module comprises a laser displacement sensor, a MEMS (Micro-Electro-Mechanical Systems) micromirror array, an FPGA (Field-Programmable Gate Array) controller and a focusing optical module; wherein the laser displacement sensor is located at the front end of the cutting head body, at a preset distance from the laser beam outlet, and at a preset angle with the axis of the laser beam, and is used to scan the surface of the cut object at a preset length in front of the laser focus moving direction to obtain surface height information; the MEMS micromirror array is located between the beam expander and the focusing optical module, and is used to control the direction in which the laser beam enters the focusing optical module; the focusing optical module is located between the MEMS micromirror array and the laser beam outlet, and is used to focus the laser beam to the working surface corresponding to the cut object; the FPGA controller is used to generate a first driving signal of the MEMS micromirror array according to the surface height information, so as to drive the MEMS micromirror array to fine-tune the laser focus position.

[0008] The laser displacement sensor scans the surface topography of the object being cut (such as undulations within 5 mm) in real time in a non-contact manner. Combined with the fast response of the MEMS micromirror (the response delay is usually less than 0.1 ms) and the closed-loop control of the FPGA, it can achieve a focus position compensation accuracy of 0.1 micron, thereby reducing the fluctuation of the cutting slit width and greatly improving the cutting accuracy and stability of the laser cutting machine.

[0009] Furthermore, the area at a preset length in front of the laser focus movement direction of the laser displacement sensor forms a preset angle with the axis of the light beam, which can predict the surface height change in advance, thereby providing sufficient adjustment time for the MEMS micromirror and avoiding the problem of laser focus adjustment lag caused by the movement inertia of the cutting head body.

[0010] Furthermore, by placing the MEMS micromirror array between the beam expander and the focusing optical module, the loss of beam divergence can be avoided.

[0011] In one embodiment of the present disclosure, the focusing optical module includes: a dynamic focusing mirror and an f-theta lens; wherein the dynamic focusing mirror is located between the f-theta lens and the MEMS micromirror array, and is used to coarsely adjust the position of the laser focus; the f-theta lens is used to focus the laser beam onto the working surface; the FPGA controller is also used to generate a second drive signal based on the surface height information to control the dynamic focusing mirror to coarsely adjust the laser focus position.

[0012] The dynamic focusing mirror can achieve a coarse adjustment range within a certain range. Combined with the fine adjustment range of the MEMS micromirror, the total compensation amount can be increased, and the cut material with greater thickness fluctuations can be processed. The f-theta lens compensates for scanning distortion through nonlinear focal length mapping to ensure that the spot diameter fluctuates less within the processing range and avoid uneven cutting caused by edge defocusing. The dynamic focusing mirror can be activated only when the overall thickness of the material changes significantly, and the MEMS can be responsible for high-frequency small adjustments. Compared with the traditional full-stroke motor drive solution, the energy consumption is greatly reduced.

[0013] In one embodiment of the present disclosure, the focusing optical module also includes a CCD (Charge-Coupled Device) sensor, which is arranged in the cutting head body and is used to obtain a two-dimensional light intensity distribution image at the laser focus; the FPGA controller is also used to calculate the laser spot diameter based on the two-dimensional light intensity distribution image; when the spot diameter is greater than the diameter threshold, a third driving signal is generated according to the spot diameter to drive the MEMS micromirror array to fine-tune the laser focus position.

[0014] The two-dimensional light intensity distribution at the laser focus is captured by CCD, and the diameter of the laser spot is calculated in real time by the FPGA controller. The MEMS micromirror array is controlled according to the diameter to fine-tune the laser focus, which can avoid focus diffusion caused by lens contamination or thermal drift. When the spot diameter is detected to be out of tolerance, the FPGA immediately generates a third drive signal, and the MEMS micromirror is linked to adjust the beam incident angle to compensate for the focus offset and ensure cutting consistency. For example, in glass cutting, the incidence of edge collapse can be reduced. A closed-loop feedback mechanism based on the CCD sensor is realized, which is conducive to maintaining the stability of laser cutting in the long term.

[0015] In one embodiment of the present disclosure, it also includes: a CMOS (Complementary Metal Oxide Semiconductor) camera, an infrared thermal imager and a processing parameter controller; the CMOS camera is used to capture the molten pool image of the surface; the infrared thermal imager is used to obtain the temperature field distribution of a preset area around the laser focus; the processing parameter controller is used to adjust the processing parameters according to the molten pool image and the temperature field distribution, and the processing parameters include at least one of the laser power, cutting speed, and the air pressure of the blowing airflow.

[0016] The CMOS camera is used to capture the molten pool image, and the infrared thermal imager is used to monitor the temperature field distribution. The processing parameter controller synchronously adjusts the processing parameters according to the molten pool image and the temperature field distribution. This can reduce the generation of burrs in the cutting gap and ensure the stability of the cutting gap, greatly reducing the rework rate.

[0017] In one embodiment of the present disclosure, a molten pool feature extraction model and a parameter adjustment model are stored in the processing parameter controller; the processing parameter controller is used to process the molten pool image using the molten pool feature extraction model to obtain the molten pool size characteristics, and calculate the molten pool area based on the molten pool size characteristics; and adjust the processing parameters using the parameter adjustment model, the molten pool area and the temperature field distribution.

[0018] By deploying the melt pool feature extraction model and parameter adjustment model, fully automatic optimization of processing parameters is achieved.

[0019] In one embodiment of the present disclosure, the processing parameters include laser power, cutting speed, and air pressure of the blow-off airflow; the parameter adjustment model is expressed as follows: if the molten pool area is smaller than the area threshold, the laser power is increased by 10%×|area difference| / area threshold, and the cutting speed is reduced by 5%×|area difference| / area threshold; if the molten pool area is not smaller than the area threshold and the temperature gradient is greater than the preset gradient, the air pressure is increased by the preset air pressure value.

[0020] If the molten pool area is smaller than the area threshold (e.g. 2mm²), increasing the power in proportion (10%×area difference / threshold) and reducing the speed (5%×area difference / threshold) can ensure that the energy density matches the cutting requirements and avoid incomplete cutting defects. When the temperature gradient is greater than the preset gradient, the automatic boost cooling method can reduce the width of the heat-affected zone, which is beneficial to ensure that the properties of heat-sensitive materials are not affected after processing.

[0021] In one embodiment of the present disclosure, the melt pool feature extraction model is YOLOv8.

[0022] YOLOv8 can achieve an inference speed of 30fps, meeting the real-time requirements of high-speed cutting.

[0023] In one embodiment of the present disclosure, it also includes: a multi-channel proportional valve for adjusting the ratio of nitrogen to oxygen in the purge gas flow; an air pressure controller for adjusting the air pressure of the purge gas flow; the processing parameter controller stores the thickness value of the cut object and the gas control model; the processing parameter controller is also used to adjust the multi-channel proportional valve and the air pressure controller according to the gas control model, the thickness value, the molten pool image and the cutting speed, so as to adjust the ratio of nitrogen to oxygen in the purge gas flow and the air pressure of the purge gas flow.

[0024] The integrated multi-channel proportional valve and gas control model realizes precise dynamic control of auxiliary gas. According to the thickness value, molten pool image and cutting speed, nitrogen (anti-oxidation) or oxygen (combustion-supporting) and gas pressure are automatically selected, realizing adaptive intelligent adjustment of gas type and pressure.

[0025] In one embodiment of the present disclosure, the gas control model is expressed as follows: the initial setting before the start of cutting is: if the thickness value is less than the preset thickness value, the multi-channel proportional valve and the air pressure controller are controlled so that the blowing gas flow is all nitrogen and the air pressure of the blowing gas flow is the first air pressure; if the thickness value is not less than the preset thickness value, the multi-channel proportional valve and the air pressure controller are controlled so that the blowing gas flow is all oxygen and the air pressure of the blowing gas flow is the second air pressure, and the second air pressure is greater than the first air pressure; the setting during the cutting process is: if the thickness value is less than the preset thickness value and the molten pool width is greater than the molten pool width threshold, the air pressure controller is adjusted to increase the air pressure of the blowing gas flow at a preset rate; if the thickness value is less than the preset thickness value and the burr height is greater than the burr height threshold, the multi-channel proportional valve is controlled so that the ratio of nitrogen to oxygen in the blowing gas flow is 9:1; if the thickness value is not less than the preset thickness value and the cutting speed is lower than the cutting speed threshold, the multi-channel proportional valve is controlled to increase the oxygen content in the blowing gas flow.

[0026] For thin plates (less than the preset thickness value), nitrogen + low pressure is used to inhibit oxidation. For thick plates (not less than the preset thickness value), oxygen + high pressure is used to enhance penetration, which can increase the speed in thick plate cutting. If the molten pool width exceeds the limit (the molten pool width is greater than the molten pool width threshold) during cutting, the pressure is increased at the preset rate to enhance the slag removal ability and avoid optical path disturbance caused by sudden changes in air pressure. When the cutting speed is lower than the speed threshold, the oxygen ratio is automatically increased to improve energy utilization and solve the speed collapse problem in complex contour cutting.

[0027] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0029] Figure 1 A schematic diagram showing a laser cutting machine in one embodiment of the present disclosure; Figure 2 A schematic diagram showing a focusing optical module in one embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the disclosure will be more comprehensive and complete and to fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0031] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings represent the same or similar parts, and thus their repeated descriptions will be omitted. It should be noted that the concepts of "first", "second", etc. mentioned in the present disclosure are only used to distinguish different "units", "modules" and other "components (structures)".

[0032] like Figure 1 As shown, the laser cutting machine in the embodiment of the present application may include: a beam expander 1, a focus control module, a cutting head body 3 and a laser beam outlet 4.

[0033] It should be noted that laser cutting machines do not only include Figure 1As for the parts shown, other parts can be configured and functionally implemented according to the structure in the prior art, and will not be described in detail in the embodiments of the present application.

[0034] The focus control module includes a laser displacement sensor 21 , a MEMS micromirror array 22 , an FPGA controller and a focusing optical module 23 .

[0035] Figure 1 The FPGA controller is not drawn in the figure because the FPGA controller can be arbitrarily configured in different positions while ensuring communication connection with other structures that need to perform data processing.

[0036] Among them, the laser displacement sensor 21 is located at the front end of the cutting head body 3, at a preset distance from the laser beam outlet 4, and at a preset angle with the axis of the laser beam. It is used to scan the surface of the cut object at a preset length in the direction of laser focus movement to obtain surface height information.

[0037] The embodiments of the present application do not limit the specific model of the laser displacement sensor 21. For example, the laser displacement sensor 21 may be Keyence LK-G5000 (a laser displacement sensor).

[0038] The embodiments of the present application do not limit the values ​​of the preset distance, preset angle, and preset length. For example, the preset distance is 5 mm, the preset angle is any angle between 30° and 45°, and the preset length is 5 mm.

[0039] The MEMS micromirror array 22 is located between the beam expander 1 and the focusing optical module 23 , and is used to control the direction in which the laser beam enters the focusing optical module 23 .

[0040] The embodiments of the present application do not limit the specific model of the MEMS micromirror array 22. For example, the MEMS micromirror array 22 may be a Texas Instruments DLP6500 (a MEMS micromirror array), which has a deflection angle of ±12° and a response time of less than 5 microseconds, and can dynamically adjust the position of the laser focus.

[0041] The focusing optical module 23 is located between the MEMS micro-mirror array 22 and the laser beam outlet 4 and is used to focus the laser beam onto a working surface corresponding to the object to be cut.

[0042] When cutting materials with a laser cutting machine, it is necessary to predetermine the working surface according to the location and thickness of the material, and use the working surface as a reference surface to pre-determine working parameters such as focusing.

[0043] The embodiment of the present application does not limit the specific material of the object to be cut. For example, the object to be cut is a steel plate, ceramics, etc.

[0044] The FPGA controller is used to generate a first driving signal of the MEMS micromirror array 22 according to the surface height information, so as to drive the MEMS micromirror array 22 to fine-tune the laser focus position.

[0045] The embodiments of the present application do not limit how the FPGA controller generates the first driving signal of the MEMS micromirror array according to the surface height information.

[0046] First, the laser displacement sensor 21 scans the surface morphology of the material being cut. The laser displacement sensor 21 scans the area in front of the cutting path (the surface of the object being cut at a preset length in front of the laser focus moving direction) at a certain frequency (determined by the specific model of the laser displacement sensor) to generate surface height information (specifically, it can be a height distribution matrix H (x, y)). In one embodiment, how the FPGA controller generates a first driving signal for the MEMS micromirror array based on surface height information may include: calculating a required laser focus offset based on the height information; calculating an angle value to be adjusted based on the offset requirement; and generating a first driving signal based on the angle value to be adjusted to drive the MEMS micromirror array to deflect according to the angle value to be adjusted.

[0047] In one embodiment, the required amount of laser focus offset is calculated based on the height information, which can be calculated according to the following formula 1: (1) in, is the height of the preset working surface, is the height value measured by the laser displacement sensor (the height value at each position (x, y) is obtained according to H(x, y)), The focal length used by the laser cutting machine, is the offset demand.

[0048] In one embodiment, the angle value to be adjusted is calculated according to the required offset, which can be calculated according to the following formula 2: (2) The inverse sine function, is the angle value to be adjusted.

[0049] Afterwards, according to the control logic of the MEMS micromirror array, The first driving signal is converted into a first driving signal for controlling the MEMS micromirror array.

[0050] The laser displacement sensor scans the surface topography of the object being cut (such as undulations within 5 mm) in real time in a non-contact manner. Combined with the fast response of the MEMS micromirror (the response delay is usually less than 0.1 ms) and the closed-loop control of the FPGA, it can achieve a focus position compensation accuracy of 0.1 micron, thereby reducing the fluctuation of the cutting slit width and greatly improving the cutting accuracy and stability of the laser cutting machine.

[0051] Furthermore, the area at a preset length in front of the laser focus movement direction of the laser displacement sensor forms a preset angle with the axis of the light beam, which can predict the surface height change in advance, thereby providing sufficient adjustment time for the MEMS micromirror and avoiding the problem of laser focus adjustment lag caused by the movement inertia of the cutting head body.

[0052] Furthermore, by placing the MEMS micromirror array between the beam expander and the focusing optical module, the loss of beam divergence can be avoided.

[0053] In one embodiment, Figure 2 As shown, the focusing optical module 23 includes a dynamic focusing mirror 231 and an f-theta lens 232 .

[0054] The dynamic focusing mirror 231 is located between the f-theta lens 232 and the MEMS micro-mirror array 22 and is used for coarsely adjusting the position of the laser focus.

[0055] The f-theta lens 232 is used to focus the laser beam onto the working surface.

[0056] The FPGA controller is also used to generate a second driving signal according to the surface height information to control the dynamic focusing mirror to roughly adjust the laser focus position.

[0057] The embodiments of the present application do not limit how the FPGA controller generates the second drive signal based on the surface height information.

[0058] In one embodiment, generating a second driving signal according to the surface height information may include: calculating a laser focus offset requirement according to the height information; and generating a second driving signal according to the offset requirement if the offset requirement is not less than a coarse adjustment threshold.

[0059] In one embodiment, how the FPGA controller generates a first drive signal for a MEMS micromirror array based on surface height information may include: calculating a required laser focus offset based on the height information; when the required offset is less than a coarse adjustment threshold, calculating an angle value to be adjusted based on the required offset; and generating a first drive signal based on the angle value to be adjusted to drive the MEMS micromirror array to deflect according to the angle value to be adjusted.

[0060] The embodiment of the present application does not limit the specific value of the coarse adjustment threshold, which can be determined based on the adjustment accuracy of the dynamic focusing mirror 231 and experience.

[0061] The dynamic focusing mirror can achieve a coarse adjustment range within a certain range. Combined with the fine adjustment range of the MEMS micromirror, the total compensation amount can be increased, and the cut material with greater thickness fluctuations can be processed. The f-theta lens compensates for scanning distortion through nonlinear focal length mapping to ensure that the spot diameter fluctuates less within the processing range and avoid uneven cutting caused by edge defocusing. The dynamic focusing mirror can be activated only when the overall thickness of the material changes significantly, and the MEMS can be responsible for high-frequency small adjustments. Compared with the traditional full-stroke motor drive solution, the energy consumption is greatly reduced.

[0062] In one embodiment, the focusing optical module further includes a CCD sensor, which is disposed in the cutting head body 3 and is used to obtain a two-dimensional light intensity distribution image at the laser focus.

[0063] The FPGA controller is also used to calculate the laser spot diameter according to the two-dimensional light intensity distribution image; when the spot diameter is greater than a diameter threshold, a third driving signal is generated according to the spot diameter to drive the MEMS micromirror array to fine-tune the laser focus position.

[0064] The embodiments of the present application do not limit how to calculate the laser spot diameter based on the two-dimensional light intensity distribution image.

[0065] In one embodiment, calculating the laser spot diameter according to the two-dimensional light intensity distribution image may include: denoising the two-dimensional light intensity distribution image to obtain a denoised image; detecting the edge contour of the spot in the denoised image; and calculating the spot diameter according to the edge contour of the spot.

[0066] In one embodiment, the two-dimensional light intensity distribution image may be denoised according to the following processing method of Formula 3: (3) in, The coordinates in the denoised image are The light intensity value of the pixel at is the background light intensity, which can be obtained by measuring, The coordinates in the denoised image are The light intensity value after denoising.

[0067] In one embodiment, detecting the edge contour of the light spot in the denoised image may include: detecting the edge contour of the light spot using a threshold method.

[0068] For example, with the maximum light intensity As the boundary threshold, the boundary condition is as shown in Formula 4: (4) in, is the maximum light intensity in the denoised image.

[0069] The embodiments of the present application do not limit the specific value of the diameter threshold, which can be determined based on actual needs and experience.

[0070] The two-dimensional light intensity distribution at the laser focus is captured by CCD, and the diameter of the laser spot is calculated in real time by the FPGA controller. The MEMS micromirror array is controlled according to the diameter to fine-tune the laser focus, which can avoid focus diffusion caused by lens contamination or thermal drift. When the spot diameter is detected to be out of tolerance, the FPGA immediately generates a third drive signal, and the MEMS micromirror is linked to adjust the beam incident angle to compensate for the focus offset and ensure cutting consistency. For example, in glass cutting, the incidence of edge collapse can be reduced. A closed-loop feedback mechanism based on the CCD sensor is realized, which is conducive to maintaining the stability of laser cutting in the long term.

[0071] In one embodiment, the laser cutting machine further includes: a CMOS camera, an infrared thermal imager and a processing parameter controller.

[0072] The processing parameter controller may be a control host of a laser cutting machine.

[0073] The CMOS camera is used to capture the molten pool image of the surface.

[0074] The infrared thermal imager is used to obtain the temperature field distribution of a preset area around the laser focus.

[0075] The processing parameter controller is used to adjust the processing parameters according to the molten pool image and the temperature field distribution. The processing parameters include at least one of the laser power, the cutting speed, and the pressure of the blowing air flow.

[0076] The CMOS camera is used to capture the molten pool image, and the infrared thermal imager is used to monitor the temperature field distribution. The processing parameter controller synchronously adjusts the processing parameters according to the molten pool image and the temperature field distribution. This can reduce the generation of burrs in the cutting gap and ensure the stability of the cutting gap, greatly reducing the rework rate.

[0077] In one embodiment, the processing parameter controller stores a molten pool feature extraction model and a parameter adjustment model.

[0078] The processing parameter controller is used to use the molten pool feature extraction model to process the molten pool image, obtain the molten pool size characteristics, and calculate the molten pool area according to the molten pool size characteristics; use the parameter adjustment model, the molten pool area and the temperature field distribution to adjust the processing parameters.

[0079] By deploying the melt pool feature extraction model and parameter adjustment model, fully automatic optimization of processing parameters is achieved.

[0080] In one embodiment, the processing parameters include laser power, cutting speed, and air pressure of the blow-off airflow, and the parameter adjustment model is expressed as follows: If the molten pool area is smaller than the area threshold, the laser power is increased by 10%×|area difference| / area threshold, and the cutting speed is reduced by 5%×|area difference| / area threshold.

[0081] If the molten pool area is not less than the area threshold and the temperature gradient is greater than the preset gradient, the gas pressure is increased by the preset gas pressure value.

[0082] The area difference is the difference between the actual molten pool area and the area threshold. The specific value of the area threshold is not limited in the embodiments of the present application and can be set according to experience and needs.

[0083] If the molten pool area is smaller than the area threshold (e.g. 2mm²), increasing the power in proportion (10%×area difference / threshold) and reducing the speed (5%×area difference / threshold) can ensure that the energy density matches the cutting requirements and avoid incomplete cutting defects. When the temperature gradient is greater than the preset gradient, the automatic boost cooling method can reduce the width of the heat-affected zone, which is beneficial to ensure that the properties of heat-sensitive materials are not affected after processing.

[0084] In one embodiment, the molten pool feature extraction model is YOLOv8. The molten pool feature extraction model can be used to extract the molten pool size from the molten pool image, and then calculate the molten pool area according to the molten pool size.

[0085] YOLOv8 can achieve an inference speed of 30fps, meeting the real-time requirements of high-speed cutting.

[0086] In one embodiment, the laser cutting machine further comprises: a multi-channel proportional valve for adjusting the ratio of nitrogen to oxygen in the purge gas flow.

[0087] Air pressure controller, used to adjust the air pressure of the blow-off air flow.

[0088] The processing parameter controller stores the thickness value of the cut object and the gas control model; the processing parameter controller is also used to adjust the multi-channel proportional valve and the air pressure controller according to the gas control model, the thickness value, the molten pool image and the cutting speed to adjust the ratio of nitrogen to oxygen in the purge gas flow and the gas pressure of the purge gas flow.

[0089] The integrated multi-channel proportional valve and gas control model realizes precise dynamic control of auxiliary gas. According to the thickness value, molten pool image and cutting speed, nitrogen (anti-oxidation) or oxygen (combustion-supporting) and gas pressure are automatically selected, realizing adaptive intelligent adjustment of gas type and pressure.

[0090] In one embodiment, the gas regulation model is expressed as follows: The initial settings before cutting starts are: If the thickness value is less than the preset thickness value, the multi-channel proportional valve and the air pressure controller are controlled so that the purge gas flow is entirely nitrogen gas and the gas pressure of the purge gas flow is the first gas pressure; If the thickness value is not less than the preset thickness value, the multi-channel proportional valve and the air pressure controller are controlled so that the blowing air flow is entirely oxygen and the air pressure of the blowing air flow is a second air pressure which is greater than the first air pressure.

[0091] The settings during cutting are: If the thickness value is less than a preset thickness value and the molten pool width is greater than a molten pool width threshold, the air pressure controller is adjusted to increase the air pressure of the blow-off air flow at a preset rate; If the thickness value is less than the preset thickness value and the burr height is greater than the burr height threshold, the multi-channel proportional valve is controlled so that the ratio of nitrogen to oxygen in the purge airflow is 9:1; If the thickness value is not less than the preset thickness value and the cutting speed is lower than the cutting speed threshold, the multi-channel proportional valve is controlled to increase the oxygen content in the blowing air flow.

[0092] For thin plates (less than the preset thickness value), nitrogen + low pressure is used to inhibit oxidation. For thick plates (not less than the preset thickness value), oxygen + high pressure is used to enhance penetration, which can increase the speed in thick plate cutting. If the molten pool width exceeds the limit (the molten pool width is greater than the molten pool width threshold) during cutting, the pressure is increased at the preset rate to enhance the slag removal ability and avoid optical path disturbance caused by sudden changes in air pressure. When the cutting speed is lower than the speed threshold, the oxygen ratio is automatically increased to improve energy utilization and solve the speed collapse problem in complex contour cutting.

[0093] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. The present disclosure is intended to cover any variations, uses or adaptations of the present disclosure, which follow the general principles of the present disclosure and include common knowledge or customary technical means in the art that are not disclosed in the present disclosure. The description and examples are to be regarded as exemplary only, and the true scope of the present disclosure is indicated by the appended claims.

Claims

1. A laser cutting machine, characterized in that: include: Beam expander, focus control module, cutting head body and laser beam outlet; The focus control module includes a laser displacement sensor, a micro-electromechanical system (MEMS) micro-mirror array, a field programmable gate array (FPGA) controller and a focusing optical module; The laser displacement sensor is located at the front end of the cutting head body, at a preset distance from the laser beam outlet, and at a preset angle with the axis of the laser beam, and is used to scan the surface of the object being cut at a preset length in the direction of movement of the laser focus to obtain surface height information; The MEMS micromirror array is located between the beam expander and the focusing optical module, and is used to control the direction in which the laser beam enters the focusing optical module; The focusing optical module is located between the MEMS micromirror array and the laser beam outlet, and is used to focus the laser beam onto the working surface corresponding to the object to be cut; The FPGA controller is used to generate a first driving signal for the MEMS micromirror array according to the surface height information, so as to drive the MEMS micromirror array to fine-tune the laser focus position.

2. The laser cutting machine according to claim 1, characterized in that: The focusing optical module includes: a dynamic focusing mirror and an f-theta lens; Wherein, the dynamic focusing mirror is located between the f-theta lens and the MEMS micromirror array, and is used for coarsely adjusting the position of the laser focus; The f-theta lens is used to focus the laser beam onto the working surface; The FPGA controller is also used to generate a second driving signal according to the surface height information to control the dynamic focusing mirror to roughly adjust the laser focus position.

3. The laser cutting machine according to claim 1, characterized in that: The focusing optical module further comprises a charge coupled device (CCD) sensor, which is arranged in the cutting head body and is used to obtain a two-dimensional light intensity distribution image at the laser focus; The FPGA controller is also used to calculate the laser spot diameter according to the two-dimensional light intensity distribution image; when the spot diameter is greater than a diameter threshold, a third driving signal is generated according to the spot diameter to drive the MEMS micromirror array to fine-tune the laser focus position.

4. The laser cutting machine according to claim 1, characterized in that: Also includes: CMOS camera, infrared thermal imager and processing parameter controller; The CMOS camera is used to capture the molten pool image on the surface; The infrared thermal imager is used to obtain the temperature field distribution of a preset area around the laser focus; The processing parameter controller is used to adjust the processing parameters according to the molten pool image and the temperature field distribution, and the processing parameters include at least one of laser power, cutting speed, and air pressure of the blowing air flow.

5. The laser cutting machine according to claim 4, characterized in that: The processing parameter controller stores a molten pool feature extraction model and a parameter adjustment model; The processing parameter controller is used to use the molten pool feature extraction model to process the molten pool image, obtain the molten pool size characteristics, and calculate the molten pool area according to the molten pool size characteristics; and use the parameter adjustment model, the molten pool area and the temperature field distribution to adjust the processing parameters.

6. The laser cutting machine according to claim 5, characterized in that: The processing parameters include laser power, cutting speed, and air pressure of the blowing air flow; the parameter adjustment model is expressed as follows: If the molten pool area is smaller than the area threshold, the laser power is increased by 10%×|area difference| / area threshold, and the cutting speed is reduced by 5%×|area difference| / area threshold; If the molten pool area is not less than the area threshold and the temperature gradient is greater than a preset gradient, the gas pressure is increased by a preset gas pressure value.

7. The laser cutting machine according to claim 5, characterized in that: The melt pool feature extraction model is YOLOv8.

8. The laser cutting machine according to claim 4, characterized in that: Also includes: Multi-channel proportional valve, used to adjust the ratio of nitrogen to oxygen in the purge gas flow; An air pressure controller, used to adjust the air pressure of the blow-off air flow; The processing parameter controller stores the thickness value of the cut object and the gas control model; the processing parameter controller is also used to adjust the multi-channel proportional valve and the air pressure controller according to the gas control model, the thickness value, the molten pool image and the cutting speed to adjust the ratio of nitrogen to oxygen in the blowing air flow and the air pressure of the blowing air flow.

9. The laser cutting machine according to claim 8, characterized in that: The gas control model is expressed as follows: The initial settings before cutting starts are: If the thickness value is less than the preset thickness value, the multi-channel proportional valve and the air pressure controller are controlled so that the purge airflow is entirely nitrogen and the air pressure of the purge airflow is the first air pressure; If the thickness value is not less than the preset thickness value, controlling the multi-channel proportional valve and the air pressure controller so that the blowing airflow is entirely oxygen and the air pressure of the blowing airflow is a second air pressure, which is greater than the first air pressure; The settings during cutting are: If the thickness value is less than a preset thickness value and the molten pool width is greater than a molten pool width threshold, adjusting the air pressure controller to increase the air pressure of the blow-off airflow at a preset rate; If the thickness value is less than the preset thickness value and the burr height is greater than the burr height threshold, the multi-channel proportional valve is controlled so that the ratio of nitrogen to oxygen in the purge airflow is 9:1; If the thickness value is not less than the preset thickness value and the cutting speed is lower than the cutting speed threshold, the multi-channel proportional valve is controlled to increase the oxygen content in the blowing air flow.

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