Centering device special for laser cutting light beam and using method

Abstract

The invention relates to the technical field of laser centering, in particular to a centering device special for laser cutting light beams and a using method. And in combination with vision and a special adjusting device, coaxial adjustment of a laser beam and the center of the nozzle can be rapidly completed through a self-adaptive algorithm, the intelligent level of the laser cutting machine is improved, and an important link of laser cutting full-automatic machining is complemented. The centering device comprises a motor module connected with the laser cutting head, an imaging device, a visual acquisition device and a control unit; according to the method, a visual collection device and an imaging device are matched to collect the center position of a nozzle and the center position of red light of a laser, the center position is converted into the movement distance of a motor module in a centering device in real time through a self-adaptive algorithm, and position offset is conducted on a focusing lens in a laser cutting head; by calculating the position deviation value of the nozzle center and the red light center of the laser, centering is ensured to meet the requirement, so that coaxial adjustment of the laser beam and the nozzle center is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of laser centering, and in particular to a centering device dedicated to laser cutting beams and a method of using the device. Background Art

[0002] Laser cutting involves irradiating a workpiece with a high-power density laser beam, causing the irradiated material to rapidly melt and evaporate. Simultaneously, a high-speed auxiliary cutting airflow blows away the molten material, thereby severing the workpiece. During this process, whether the laser beam is coaxial with the center of the nozzle significantly impacts cutting quality and stability. First, misalignment between the laser beam and the nozzle can cause the nozzle to overheat, shortening its lifespan and, in severe cases, even causing damage. Second, the capacitance value collected based on the nozzle can fluctuate abnormally, affecting the accuracy of cutting height control and, consequently, cutting stability. Finally, variations in cutting airflow and beam quality can lead to inconsistencies in cutting cross-sections and accuracy in different directions.

[0003] To address this issue, the traditional approach is for the operator to use auxiliary tools such as scotch tape and a wrench. The system's laser burst function briefly activates the laser beam to burn through the scotch tape to form a hole. The operator then visually identifies the error between the hole and the nozzle's outer contour, and then tightens the lens adjustment screw based on experience. This operation is repeated multiple times to achieve coaxial adjustment between the beam and the nozzle center. The operator's adjustment method using scotch tape and a wrench relies entirely on manual judgment to adjust the accuracy. As the laser cutting process continues to become more intelligent, traditional methods are no longer adaptable to high-speed automated processes. Therefore, a fully automatic adjustment method that can replace manual effort to achieve coaxial adjustment between the laser beam and the nozzle center is urgently needed. Summary of the Invention

[0004] The problem to be solved by the present invention is to provide a fully automatic adjustment method that can replace manual adjustment of the coaxial adjustment of the laser beam and the nozzle center. This method has the advantages of safety, high efficiency, high adjustment accuracy, etc., and is an important link in realizing fully automatic laser processing.

[0005] In view of the shortcomings of the prior art, the present invention solves the technical problems by adopting the following technical solutions:

[0006] A centering device specially used for laser cutting beams and a method of use, comprising a motor module connected to a laser cutting head, an imaging device arranged below the laser cutting head, a visual acquisition device and a control unit arranged below the imaging device; the motor module comprises an adjusting rod, a connecting plate, a small coupling and a dual servo motor connected in sequence, wherein one end of the adjusting rod can adjust the position of a focusing lens in the laser cutting head after being driven by the dual servo motor; the imaging device comprises a sealing cover plate, an upper fixing plate of the imaging lens, a red light attenuation lens, a lower fixing plate of the imaging lens, a cylinder and a centering device box, wherein the sealing cover plate is mounted on the top of the centering device box and a through hole is provided in the center, and the cylinder can push the red light attenuation lens to move to the bottom of the through hole; the visual acquisition device is arranged at the lower part of the centering device box, and is used to obtain the center of the laser cutting head nozzle and the position of the laser indication red light.

[0007] Preferably, the visual acquisition device includes a customized light source, a light source connecting bracket, a camera lens, an industrial camera, a camera connecting bracket and a mounting base. The light source connecting bracket is used to connect the customized light source; the camera connecting bracket is used to connect the industrial camera; and the mounting base is connected to the bottom end of the centering device box.

[0008] Preferably, two slide grooves are provided opposite to each other in the top side walls of the centering device box, and the length direction of the slide grooves is along the movement direction of the red light attenuation lens; the two sides of the lower fixing plate of the imaging lens are respectively inserted into the two slide grooves, and the red light attenuation lens is clamped between the lower fixing plate of the imaging lens and the upper fixing plate of the imaging lens. The output end of the cylinder is connected to the lower fixing plate of the imaging lens, and the cylinder can push the lower fixing plate of the imaging lens to move along the two slide grooves.

[0009] Preferably, the control unit is integrated into the machine tool control system and is used for controlling the motor module, imaging device and visual acquisition device and for linkage with the laser control system.

[0010] A method for using a centering device specifically for laser cutting beams comprises the following steps:

[0011] S1: Positioning the laser cutting head: Position the laser cutting head above the centering device and bring the laser cutting head close to the through hole reserved in the sealing cover plate;

[0012] S2: take the cutting nozzle image;

[0013] S3: The image software processes the cutting nozzle image, calculates the cutting nozzle center position (X0, Y0) and compares the aperture size and cutting nozzle surface quality. If the aperture size and cutting nozzle surface instructions do not meet the current system settings, an alarm will be issued and all actions will be interrupted;

[0014] S4: The industrial camera captures the red indicator light image and transmits it to the imaging software;

[0015] S5: The image software processes the red indicator light image and obtains the current red light center position (P x ,P y );

[0016] S6: Determine the motion position coordinates of the dual servo motors based on the built-in algorithm of the control unit (M u ,M v ), the M set by the control unit's built-in algorithm u 、M v The two position coordinates start the dual servo motors for positioning;

[0017] S7: Based on the motion position coordinates M in S6 u 、M v Adjust the focus lens position: The dual servo motors adjust the focus lens position of the laser cutting head through a small coupling and an adjusting rod, so that the center of the red light is close to the center of the cutting nozzle.

[0018] S8: The industrial camera takes the red indicator light image again and calculates the center position of the red light after adjustment (P x ,P y ), then compare the deviation between the red light center and the cutting nozzle center after adjustment. If the deviation exceeds the set threshold, continue to repeat the process of S6-S8 until the deviation between the red light center and the cutting nozzle center is within the set threshold;

[0019] S9: Lift the laser cutting head to a safe height and the centering action is completed.

[0020] Preferably, capturing the cutting nozzle image in S2 specifically includes the cylinder pulling back the red light attenuation lens, the control unit turning on the customized light source, and turning off the laser red indicator light, and the through-hole industrial camera can capture the cutting nozzle above to obtain the cutting nozzle image.

[0021] Preferably, the industrial camera in S4 captures the red indicator light image specifically including: the cylinder pushes the red light attenuation lens out so that the red light attenuation lens is located below the cutting nozzle and above the camera lens, the control unit turns off the customized light source, and turns on the laser red indicator light, the industrial camera obtains the laser red indicator light image, and transmits it to the image software.

[0022] Preferably, the process of determining the motion position coordinates of the dual servo motors in S6 is as follows: according to the red light center (P x ,P y ) in machine tool O XY The control unit converts the red light center into the motion coordinate system of the focusing lens O UV Center position coordinate, O UV Coordinate index O U , OV is the motion position coordinate of the dual servo motors (M u ,M v ), the control unit then calculates the motion position coordinates (M u ,M v ) Start the dual servo motors for positioning.

[0023] Preferably, the red light center position (P x ,P y The deviation ‖e‖ from the cutting nozzle center (X0, Y0) is calculated as follows:

[0024] The threshold value of the deviation ‖e‖ is not greater than 0.03 mm. The beneficial effects of the present invention are as follows:

[0025] 1) This invention incorporates an imaging device that can acquire the coordinates of the red light at the nozzle in real time, reducing the precision requirements for beam transmission within the laser cutting head. Furthermore, the quality of the indicator red light often varies between laser sources of different brands and powers, and this imaging device can mitigate this effect.

[0026] 2) Add nozzle quality detection function, which can detect nozzle quality and aperture size simultaneously when obtaining nozzle center. If the nozzle does not meet the use requirements, the system will alarm to remind the operator to replace it in time;

[0027] 3) The motor module adopts a modular solution for external installation, which can be compatible with various industry-standard laser cutting heads through simple size adjustment; the position deviation between the red light center and the cutting nozzle center is converted into adjustment of the dual servo motor 240. Compared with the traditional adjustment method of visually identifying the tape holes and the outer contour traces of the nozzle, the method of the present invention is more precise and controllable, and does not need to rely on manual experience. As the laser cutting process continues to become intelligent, the method of the present invention can adapt to high-speed automated processes;

[0028] 4) Adopting adaptive algorithm, by obtaining the red light position in real time, the error caused by the difference in focusing lens structure and transmission gap can be skipped, and the coaxial position of laser beam and nozzle center position can be quickly adjusted. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a structural diagram of a centering device according to the present invention;

[0030] Figure 2 This is a schematic diagram of an explosion of a centering device according to the present invention;

[0031] Figure 3 This is a push-pull structure diagram of the red light attenuation lens involved in the present invention;

[0032] Figure 4It is a connection block diagram of the control unit of the present invention;

[0033] Figure 5 is a flow chart of the regulation method of the present invention;

[0034] Figure 6 This is a simplified diagram of the key coordinate system involved in the present invention;

[0035] Explanation of the accompanying drawings: 1. Laser cutting head; 2. Motor module; 210. Adjusting rod; 220. Connecting plate; 230. Small coupling; 240. Dual servo motor; 3. Imaging device; 310. Sealing cover; 311. Through hole; 320. Upper fixing plate of imaging lens; 330. Red light attenuation lens; 340. Lower fixing plate of imaging lens; 350. Cylinder; 360. Centering device box; 370. Slide; 4. Visual acquisition device; 400. Customized light source; 410. Light source connecting bracket; 420. Camera lens; 430. Industrial camera; 440. Camera connecting bracket; 450. Mounting base plate; 5. Control unit. DETAILED DESCRIPTION

[0036] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are provided for purposes of illustration and description and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments are chosen and described to better illustrate the principles of the invention and its practical application, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for specific applications.

[0037] The centering device of the present invention comprises a visual acquisition device 4, an imaging device 3, a motor module 2, and a control unit 5. The visual acquisition device 4 identifies the nozzle profile and aperture size. Taking into account the fact that the laser generator's red indicator light is coaxial with the laser beam, the imaging device 3 is turned on to obtain the position of the indicator red light in real time. The control unit 5 uses an adaptive algorithm to convert this into the coordinates required for focusing lens position adjustment. Finally, the motor module 2, externally mounted on the laser cutting head 1, is used to achieve coaxial adjustment of the laser beam.

[0038] The main structure of the centering device involved in the present invention is as follows Figure 1 As shown, it includes a laser cutting head 1, a motor module 2, an imaging device 3 and a visual acquisition device 4, wherein the motor module 2 is externally mounted on the laser cutting head 1 and is connected to the focusing lens adjustment screw (see Figure 2), the motor module 2 includes two micro servo motors, supports bus communication, and can quickly adjust the plane position of the focusing lens to any position; the imaging device 3 is arranged between the laser cutting head 1 and the visual acquisition device 4, and collects the position of the laser indicating red light in real time as a basis for coaxial adjustment of the light beam; the visual acquisition device 4 is used to obtain the nozzle center and the position of the indicating red light.

[0039] Figure 2 This is an exploded schematic diagram of the centering device involved in the present invention. In the figure, the laser cutting head 1 contains a focusing lens. Moving the focusing lens position can adjust the final position of the laser.

[0040] The motor module 2 includes an adjustment rod 210, a connecting plate 220, a small coupling 230, and a dual servo motor 240. The adjustment rod 210 is a standard hexagonal rod that engages with the hexagonal screw that adjusts the position of the focusing lens in the laser cutting head 1. The connecting plate 220 connects the adjustment rod 210 to the dual servo motor 240. A small coupling 230 is installed between the dual servo motor 240 and the connecting plate 220. The small coupling 230 is mounted on the output end of the dual servo motor 240. The dual servo motor 240 is used to adjust the position of the focusing lens. The dual servo motor 240 drives the adjustment rod 210 to rotate through the small coupling 230, thereby adjusting the position of the focusing lens by loosening or tightening the adjustment screw in the laser cutting head 1.

[0041] The imaging device 3 includes a sealing cover plate 310 , an upper fixing plate 320 for an imaging lens, a red light attenuation lens 330 , a lower fixing plate 340 for an imaging lens, an air cylinder 350 and a centering device housing 360 . The sealing cover plate 310 is mounted on the top of the centering device housing 360 and has a through hole 311 in the center. The red light attenuation lens 330 is disposed between the upper fixing plate 320 of the imaging lens and the lower fixing plate 340 of the imaging lens. The red light attenuation lens 330 is used to indicate red light filtering and imaging. The output end of the cylinder 350 is connected to the lower fixing plate 340 of the imaging lens, and the red light attenuation lens 330 is clamped between the lower fixing plate 340 of the imaging lens and the upper fixing plate 320 of the imaging lens. Two sliding grooves 370 are provided in the top sidewalls of the centering device housing 360. The length of the sliding grooves 370 is along the movement direction of the red light attenuation lens 330. The two sides of the lower fixing plate 340 of the imaging lens are respectively inserted into the two sliding grooves 370. The cylinder 350 can push the lower fixing plate 340 of the imaging lens to move along the two sliding grooves 370, and the red light attenuation lens 330 can extend and retract with the lower fixing plate 340 of the imaging lens. The cylinder 350 pushes the lower fixing plate 340 of the imaging lens so that the red light attenuation lens 330 moves below the through hole 311 or is not below the through hole 311, thereby completing the horizontal movement of the red light attenuation lens 330; the sealing cover 310, the upper fixing plate 320 of the imaging lens, the red light attenuation lens 330, the lower fixing plate 340 of the imaging lens, and the cylinder 350 are all arranged on the upper part of the centering device box 360.

[0042] The visual acquisition device 4 is located below the centering device housing 360 and comprises, from top to bottom, a custom light source 400, a light source connection bracket 410, a camera lens 420, an industrial camera 430, a camera connection bracket 440, and a mounting base 450. The custom light source 400 is used to capture images of different types of cutting nozzles; the light source connection bracket 410 is used to connect the custom light source 400; the camera lens 420 is used to enhance imaging quality and control the focal length and size of the imaging field of view; the industrial camera 430 is used for initial image acquisition and, in conjunction with accompanying graphics processing software, can obtain key information such as the cutting nozzle and red light center position for centering device adjustment; the camera connection bracket 440 is used to connect the industrial camera 430; and the mounting base 450 is connected to the bottom of the centering device housing 360.

[0043] The control unit 5 is developed based on the Siemens TIA platform and is a modular program design. It is integrated into the machine tool control system and is used to control the motor module 2, imaging device 3 and visual acquisition device 4 as well as the linkage with the laser control system. The connection block diagram of the control unit 5 is shown in the figure below. Figure 4 As shown, the control unit 5 outputs instructions to control the dual servo motors 240 in the motor module 2. The dual servo motors 240 include a servo motor 1 and a servo motor 2. The servo motor 1 and the servo motor 2 are connected to the two adjusting screws of the focusing lens through a small coupling 230, thereby achieving the focusing lens on the coordinate system. UV Position adjustment (see Figure 6 ); The red indicator light spot is attenuated and imaged by the imaging device 3, and the visual acquisition device 4 obtains the light spot pattern filtered by the imaging device 3 and processes it, and calculates the center of the light spot in the standard machine tool coordinate system O XY The position in the nozzle is uploaded to the control unit 5 in real time; the visual acquisition device 4 can obtain the image of the nozzle device and calculate the nozzle center, aperture and other data required for coaxial adjustment control, and upload them to the control unit 5.

[0044] In order to realize the rapid centering function of the laser light path of the above-mentioned centering device, the present invention proposes to establish a fitting model based on spatial mapping, acquisition algorithm, motor control parameters and light spot position to realize the rapid centering of the laser light path based on the above-mentioned centering device.

[0045] 1. Coordinate system definition and spatial mapping

[0046] 1.1 Coordinate system transformation relationship

[0047] Based on the laser cutting optical path and the machine tool coordinate system, a spatial mapping model of the two is established to realize coordinate conversion to ensure that the system is centered, adjusted and processed in the same coordinate system.

[0048] See also Figure 6 , let the machine tool coordinate system be OXY Servo motor 1 and servo motor 2 rotate clockwise / counterclockwise to drive the focus lens position adjustment screw to form an O on the plane. UV Coordinates, O UV That is the motion coordinate system of the focusing lens, O XY and O UV The angle between the two is α (measured α = 45° ± 3°). The spatial point mapping relationship is:

[0049]

[0050] The rotation matrix is:

[0051]

[0052] 1.2 Dual servo motor 240-focus lens displacement model

[0053] At the same time, considering the focus lens drift problem, there are differences in the focus lens positions of different batches of cutting heads. The present invention introduces the concept of focus lens position to ensure the applicability of this algorithm for different categories and batches of cutting heads.

[0054] The displacement of the adjusting screw corresponding to the focusing lens (M u ,M v ) and the focusing lens position (U, V):

[0055] Where: k u ,k v is the transmission ratio (calibrated value); δ u ,δ v is the gap nonlinear function;

[0056] According to the adjustment screw displacement M, the nonlinear function δ(M) of the gap between the u-axis and the v-axis is expressed as follows:

[0057]

[0058] 2. Mathematical model of multi-quadrant sampling strategy

[0059] In order to ensure the accuracy of the centering algorithm calculation, the present invention proposes a light point coordinate sampling algorithm based on curvature adaptation to ensure the reliability of the data source used in the algorithm calculation.

[0060] 2.1 Sampling point distribution function

[0061] Define the polar coordinate distribution of sampling points in the nozzle plane;

[0062]

[0063] in:

[0064] D is the nozzle diameter, usually D=5mm, q=1,2,3,4 represents the quadrant number,

[0065] is the radial distribution factor, is the angular disturbance term, (r i ,θ j ) are the polar coordinates of the sampling points.

[0066] 2.2 Curvature Adaptive Sampling

[0067] Define the local curvature threshold function:

[0068]

[0069] When the curvature κ>κ max When , the newly added sampling points meet the following requirements:

[0070]

[0071] Among them, κ max is the local curvature threshold; is the position gradient; σ is the gradient sensitivity coefficient; P is the light spot position; ∈ is the curvature error threshold; D is the nozzle diameter; M u M is the displacement of the adjusting screw in the U axis. v is the component of the adjusting screw displacement in the V axis.

[0072] 3. Nonlinear mapping and parameter identification

[0073] In order to achieve accurate solution of the centering algorithm, the present invention proposes a functional relationship model between the light spot position and the position of the dual servo motor 240 based on a nonlinear mapping model, considering nonlinear parameters such as assembly clearance and lens size error as well as functional models with linear parameters such as structural dimensions and adjustment screws, so as to solve the current problems of low algorithm accuracy and difficulty in solving related solutions.

[0074] 3.1 Complete mapping equation

[0075] Light spot position P = [P x ,P y ] T With dual servo motor 240 position M=[M u ,M v ] T Relationship:

[0076]

[0077] Among them, k11, k12, k21, k22 are linear transformation coefficients; β1, β2, β3, β4 are quadratic linear transformation coefficients; an, cn are cosine coefficients; bn, dn are sine coefficients

[0078] 3.2 Regularized Least Squares Identification

[0079] The optimization problem for the parameter set Θ = [vec(K); β; vec(Γ)] is:

[0080]

[0081] The solution is:

[0082]

[0083] in is the Jacobian matrix.

[0084] 4. Description of the workflow

[0085] 4.1 Calibration Mode

[0086] (1) Initialization: M(0) = 0, P(0) = 0;

[0087] (2) Traverse quadrant q = 1 → 4:

[0088]

[0089] (3) Solve Θ * =argmin‖Pf(M)‖ 2 .

[0090] 4.2 Alignment control

[0091] (1) Set target P * =[X0,Y0] T ;

[0092] (2) When the deviation value ‖e‖>Δ: update e (k+1) =P ＊ -P (k+1) ;

[0093] After the motor module 2 completes the positioning, according to the current red light center position coordinates (P x ,P y ), and compare it with the preset target coordinate cutting nozzle center position (X0, Y0) to generate position deviation If ‖e‖ is greater than the set threshold Δ, the positioning position is automatically refreshed and adjusted again according to the above algorithm until it is within the threshold Δ. In actual tests, after 2-3 positioning cycles using the above algorithm, precise control within the threshold Δ of 0.03mm can be achieved.

[0094] The centering method introduced in this invention is developed based on the Siemens TIA control platform. The control unit 5 is integrated into the Siemens One system, and all the control of the centering device is realized by means of the PLC, servo axis, IO module and other hardware and software in the numerical control system. Figure 5 .

[0095] S1: Positioning the laser cutting head 1: accurately positioning the laser cutting head 1 above the centering device through spatial movement along the X / Y / Z axes, and placing the laser cutting head 1 close to the through hole 311 reserved in the sealing cover plate 310;

[0096] S2. Capture an image of the cutting nozzle and control the cylinder 350. Cylinder 350 pulls the red light attenuation lens 330 back along the slide groove via the connecting rod, exposing the reserved through-hole 311 on the sealing cover plate 310. Through through-hole 311, the industrial camera 430 can capture the image of the cutting nozzle above. The control unit 5 turns on the customized light source 400 and turns off the red laser indicator light to facilitate the industrial camera 430 to capture the image of the cutting nozzle. The industrial camera 430 captures the image of the cutting nozzle through the through-hole 311 of the sealing cover plate 310 and transmits it to the image software for processing.

[0097] S3. The image software processes the cutting nozzle image, calculates the cutting nozzle center position (X0, Y0) and compares the aperture size and cutting nozzle surface quality. If the aperture size and cutting nozzle surface instructions do not meet the current system settings, an alarm will be issued and all operations will be interrupted;

[0098] S4. Industrial camera 430 captures the red indicator light image. Cylinder 350, via the connecting rod, pushes red light attenuation lens 330 along the slideway, positioning it below the cutting nozzle and above camera lens 420. Control unit 5 turns off custom light source 400 and turns on the laser red indicator light. Industrial camera 430 captures the laser red indicator light image and transmits it to the image processing software.

[0099] S5. The image software processes the red indicator light image and obtains the red light center position (P x ,P y );

[0100] S6. Determine the motion position coordinates (M) of the dual servo motor 240 based on the built-in algorithm (algorithm 3.1) of the control unit 5. u ,M v ), the control unit 5 then sets M according to the built-in algorithm u 、M v The two position coordinates are respectively started by the dual servo motors 240 for positioning; according to the red light center (P x ,P y ) in machine tool O XYThe control unit 5 converts the red light center into the motion coordinate system of the focusing lens O UV Center position coordinate, O UV Coordinate index O U , O V is the motion position coordinate of the dual servo motor 240 (M u ,M v ), the control unit 5 then calculates the motion position coordinates (M u ,M v ) Start the dual servo motors 240 for positioning.

[0101] S7. Based on the motion position coordinates (M u ,M v ) Adjusting the focus lens position: The dual servo motor 240 operates to adjust the focus lens position of the laser cutting head 1. The dual servo motor 240 adjusts the focus lens position of the laser cutting head 1 through the small coupling 230 and the adjustment rod 210 so that the center of the red light is close to the center of the cutting nozzle;

[0102] S8. The industrial camera 430 captures the red indicator light image again and calculates the red light center (P x ,P y ); and then compare the red light center (P y ,P y ) and the center of the cutting nozzle (X0, Y0) deviation ‖e‖, If the deviation ‖e‖ exceeds the set threshold Δ (set to 0.03mm), continue to repeat the process of S6-S8 until the deviation ‖e‖ between the red light center and the cutting nozzle center is within the set threshold Δ;

[0103] S9. Control the Z axis to lift the laser cutting head 1 to a safe height, and the centering action is completed.

[0104] Control flow diagram see Figure 5 . The machine tool system starts the automatic coaxial adjustment function of the light beam, and the internal integrated control unit 5 first links with the machine tool system to move the laser cutting head 1 to the specified position. The visual acquisition device 4 obtains the nozzle image, calculates the absolute coordinate position of the nozzle in the CNC machine tool, and uses the visual graphics comparison algorithm to check the core parameters such as the nozzle roundness, bottom surface quality and aperture size to determine whether the current nozzle meets the processing requirements. After the nozzle detection is completed, the control unit 5 turns on the imaging device 3 and turns on the red indicator light through the control system. Move the laser cutting head 1 to the imaging device 3 again and close to the imaging device 3, so that the visual acquisition device 4 can collect the center position of the indicator red light in real time and convert it into the absolute coordinates of the machine tool. The control unit 5 obtains the deviation ‖e‖ between the red light center and the nozzle center fed back by the visual acquisition device 4, converts it into the position coordinate for controlling the dual servo motor 240 and adjusts the position in real time, (Mu ,M v ) is the dual servo motor motion position output by the algorithm. The current deviation ‖e‖ between the red light center and the nozzle center is less than the set range, deviation ‖e‖=, (P x ,P y ) is the coordinate of the current red light center position, (X0, Y0) is the cutting nozzle center position determined in S3; the beam coaxial adjustment is completed when the deviation ‖e‖ is less than the threshold Δ, that is, ‖e‖ is not greater than 0.03mm.

[0105] Compared with the beam centering devices in the industry, the device of the present invention has the following features:

[0106] 1) The addition of an imaging device 3 allows for real-time acquisition of the red light coordinates at the nozzle, reducing the precision requirements for beam conduction within the laser cutting head 1. Furthermore, the quality of the indicator red light often varies between laser sources of different brands and powers, and the use of this imaging device 3 can mitigate this effect.

[0107] 2) Add nozzle quality detection function, which can detect nozzle quality and aperture size simultaneously when obtaining nozzle center. If the nozzle does not meet the use requirements, the system will alarm to remind the operator to replace it in time;

[0108] 3) The motor module 2 adopts a modular solution for external installation, which can be compatible with various industry standard laser cutting heads through simple size adjustment;

[0109] 4) Adopting adaptive algorithm, by obtaining the red light position in real time, the error caused by the difference in focusing lens structure and transmission gap can be skipped, and the coaxial position of laser beam and nozzle center position can be quickly adjusted.

[0110] The equipment list used in the centering device of the present invention is as follows:

[0111] Serial number Name Quantity Series specifications 1 Industrial camera 1Pc Hikvision MV-CS series 2 Camera lens 1Pc Ximing 16mm matching lens 3 Image software 1Pc Hikvision authorized dongle 4 Custom light source 1Pc Annular blue light source set (including controller) 5 Laser cutting head 1Pc Preziosa Procutter 6KW cutting head 6 Red light attenuation lens 1Pc Custom attenuation coated lens 7 Servo motor 2Pc Fahrbach 2250 series 8 Control unit 1Pc Siemens One system (TIA software platform) 9 Control module 1Pc S120 servo motor, ET200SP module

Claims

1. A centering device specifically for laser cutting beams, characterized by: The invention comprises a motor module (2) connected to a laser cutting head (1), an imaging device (3) arranged below the laser cutting head (1), a visual acquisition device (4) arranged below the imaging device (3), and a control unit (5); the motor module (2) comprises an adjusting rod (210), a connecting plate (220), a small coupling (230), and a dual servo motor (240) connected in sequence, wherein one end of the adjusting rod (210) is driven by the dual servo motor (240) to adjust the position of the focusing lens in the laser cutting head (1); the imaging device (3) comprises a sealing cover plate (310) ), an imaging lens upper fixing plate (320), a red light attenuation lens (330), an imaging lens lower fixing plate (340), a cylinder (350) and a centering device box (360), wherein a sealing cover plate (310) is installed on the top of the centering device box (360) and a through hole (311) is provided at the center, and the cylinder (350) can push the red light attenuation lens (330) to move below the through hole (311); a visual acquisition device (4) is provided at the lower part of the centering device box (360) and is used to obtain the center of the nozzle of the laser cutting head (1) and the position of the laser indicator red light.

2. The centering device for laser cutting beam according to claim 1, characterized in that: The visual acquisition device (4) comprises a customized light source (400), a light source connecting bracket (410), a camera lens (420), an industrial camera (430), a camera connecting bracket (440) and a mounting base plate (450), wherein the light source connecting bracket (410) is used to connect the customized light source (400); the camera connecting bracket (440) is used to connect the industrial camera (430); and the mounting base plate (450) is connected to the bottom end of the centering device box (360).

3. The centering device for laser cutting beam according to claim 1, characterized in that: Two slide grooves (370) are arranged opposite to each other in the top side walls of the centering device housing (360), and the length direction of the slide grooves (370) is along the movement direction of the red light attenuation lens (330); the two sides of the imaging lens lower fixing plate (340) are respectively inserted into the two slide grooves (370), and the red light attenuation lens (330) is clamped between the imaging lens lower fixing plate (340) and the imaging lens upper fixing plate (320); the output end of the cylinder (350) is connected to the imaging lens lower fixing plate (340), and the cylinder (350) can push the imaging lens lower fixing plate (340) to move along the two slide grooves (370).

4. The centering device for laser cutting beam according to claim 1, characterized in that: The control unit (5) is integrated into the machine tool control system and is used for controlling the motor module (2), the imaging device (3) and the visual acquisition device (4) and for linkage with the laser control system.

5. A method for using a centering device specifically for laser cutting beams, characterized in that: The following steps are included: S1: Positioning the laser cutting head (1): Positioning the laser cutting head (1) above the centering device and placing the laser cutting head (1) close to the through hole (311) reserved in the sealing cover plate (310); S2: take the cutting nozzle image; S3: The image software processes the cutting nozzle image, calculates the cutting nozzle center position (X0, Y0) and compares the aperture size and cutting nozzle surface quality. If the aperture size and cutting nozzle surface instructions do not meet the current system settings, an alarm will be issued and all actions will be interrupted; S4: The industrial camera (430) captures the red indicator light image and transmits it to the imaging software; S5: The image software processes the red indicator light image and obtains the current red light center position (P x ,P y ); S6: Determine the motion position coordinates (M) of the dual servo motors (240) based on the built-in algorithm of the control unit (5). u ,M v ), the control unit (5) then sets the M according to the built-in algorithm u 、M v The two position coordinates start the dual servo motors (240) for positioning; S7: Based on the motion position coordinates (M u ,M v ) adjusting the position of the focusing lens: the dual servo motor (240) operates to adjust the position of the focusing lens of the laser cutting head (1). The dual servo motor (240) adjusts the position of the focusing lens of the laser cutting head (1) through a small coupling (230) and an adjustment rod (210) so that the center of the red light is close to the center of the cutting nozzle; S8: The industrial camera (430) takes the red indicator light image again and calculates the red light center position after adjustment (P x ,P y ), then compare the deviation between the red light center and the cutting nozzle center after adjustment. If the deviation exceeds the set threshold, continue to repeat the process of S6-S8 until the deviation between the red light center and the cutting nozzle center is within the set threshold; S9: Lift the laser cutting head (1) to a safe height, and the centering action is completed.

6. The method for using the centering device for laser cutting beam according to claim 5, characterized in that: The process of capturing the image of the cutting nozzle in S2 specifically includes the cylinder (350) pulling back the red light attenuation lens (330), the control unit (5) turning on the customized light source (400), and turning off the red indicator light of the laser, and the industrial camera (430) can capture the cutting nozzle above through the through hole (311) to obtain the image of the cutting nozzle.

7. The method for using the centering device for laser cutting beam according to claim 5, characterized in that: The industrial camera (430) in S4 captures the red indicator light image, specifically comprising: the cylinder (350) pushes the red light attenuation lens (330) out, so that the red light attenuation lens (330) is located below the cutting nozzle and above the camera lens (420); the control unit (5) turns off the customized light source (400) and turns on the laser red indicator light; the industrial camera (430) acquires the laser red indicator light image and transmits it to the image software.

8. The method for using the centering device for laser cutting beam according to claim 5, characterized in that: The process of determining the motion position coordinates of the dual servo motor (240) in S6 is as follows: according to the red light center (P x ,P y ) in machine tool O XY The control unit (5) converts the red light center into the motion coordinate system O of the focusing lens. UV Center position coordinate, O UV Coordinate index O U , O V is the motion position coordinate (M) of the dual servo motor (240) u ,M v ), the control unit (5) then calculates the motion position coordinates (M u ,M v ) starts the dual servo motors (240) for positioning.

9. The method for using the centering device for laser cutting beam according to claim 5, characterized in that: The red light center position after adjustment in S8 (P x ,P y The deviation ‖e‖ from the cutting nozzle center (X0, Y0) is calculated as follows: The threshold value of the deviation ‖e‖ is not greater than 0.03mm.

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