Laser cutting head control system and method

Abstract

The present invention provides a method for controlling a laser cutting head, comprising the following steps: obtaining a CAD drawing of a desired three-dimensional product to be cut, extracting the product's three-dimensional geometric information, including straight line segments, arcs, and curves from the drawing; performing laser cutting path planning; controlling the laser cutting head to move in real time according to the planned cutting path, monitoring the laser cutting head's operating environment temperature and the surface temperature of the material being cut in real time, and constructing a calculation model for the optimal laser emission power during the laser cutting process; and controlling the laser cutting head's real-time laser emission power according to the calculated optimal real-time laser power. Compared to traditional optimization methods based on mechanism models, the present invention utilizes cutting path planning for the laser cutting head based on the desired product drawing. This method can better adapt to the complex nonlinear relationship between process parameters and quality, provides more accurate prediction capabilities, and offers reliable guidance and optimization solutions for laser cutting processes.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser cutting machines, and in particular relates to a control system and method for a laser cutting head. Background Art

[0002] With the continuous development of modern manufacturing, the advantages of laser cutting technology are becoming increasingly prominent. Laser cutting technology uses a high-power density laser beam to illuminate the material to be cut, causing it to rapidly vaporize, ablate, melt, or reach its ignition point, evaporating and forming tiny holes. Simultaneously, an auxiliary high-pressure gas coaxial with the laser beam is used to blow away the molten material. As the laser beam moves, the holes continuously form narrow slits, completing the cutting of the material. Laser cutting technology offers advantages such as high cutting quality, high cutting efficiency, fast cutting speed, no contact with the material being processed, and strong applicability.

[0003] In the prior art, for example, Chinese patent application document with application number CN202210090898.0 discloses a control method and related equipment for laser cutting; and Chinese patent application document with application number CN202311710239.3 discloses a laser cutting method and device, which controls the laser beam to perform laser cutting along a first path for one cycle after responding to a laser cutting instruction, and then controls the laser beam to perform laser cutting along a second path for one cycle, and then controls the laser beam to return to the first path for laser cutting, and repeats this cycle until the ablation area between the first path and the second path is completely ablated to form a cutting gap, and the product to be cut is cut. However, it is not clear how to plan the shortest laser cutting path according to the different product graphics to be obtained, and whether it can perform corner interpolation at positions with rounded corners or turns to avoid the occurrence of burrs and the like. The laser emission power is not adjusted in real time, and thus the technical effect of energy saving cannot be achieved. Summary of the Invention

[0004] The present invention addresses these shortcomings by providing a control system and method for a laser cutting head. This laser cutting path planning system generates a cutting path based on the geometric information in a CAD drawing. By optimizing the laser head's movement trajectory and cutting sequence, and analyzing the temperature distribution based on the planned path to calculate the optimal real-time laser emission power, the system effectively ensures efficient and precise completion of the cutting task.

[0005] The present invention provides the following technical solution: a method for controlling a laser cutting head, wherein the method optimizes and controls the travel path of the laser cutting head and the laser emission power during the cutting process in real time, and the method comprises the following steps:

[0006] S1: Obtain a CAD drawing of a desired cut 3D product, and extract 3D geometric information of the product including straight line segments, arcs, and curves in the drawing;

[0007] S2: perform laser cutting path planning;

[0008] S3: Controlling the laser cutting head to move in real time according to the cutting path planned in step S2, monitoring the working environment temperature of the laser cutting head and the surface temperature of the material being cut in real time, and building a calculation model for the optimal laser emission power during the laser cutting process;

[0009] S4: Control the real-time laser emission power of the laser cutting head according to the optimal real-time laser power calculated in step S3.

[0010] Furthermore, the S1 step includes:

[0011] S11: Get the starting and ending coordinates of multiple straight line segments for each part:

[0012] L n is the nth straight line segment of the drawing, is the starting point coordinate of the nth straight line segment; is the end point of the nth straight line segment; n=1,2,…,N;

[0013] S12: Get the geometric information of multiple arcs of each part of the product:

[0014] C m is the mth arc of the drawing, is the coordinate of the center of the circle where the mth arc is located; r m is the radius of the circle where the mth arc lies, are the starting angle and ending angle of the starting point and ending point of the mth arc relative to the center of the circle; m = 1, 2, ..., M; and

[0015] S13: Obtaining coordinates of control points in multiple curves of each part of the product, forming a control point set for each curve, and fitting multiple control points in the control point set using a Bezier curve interpolation method to form a curve cutting path; Among them, C p is the set of control points of the p-th curve, is the qth control point of the pth curve, and its coordinates on the cutting plane are Q is the total number of control points of the p-th curve, p = 1, 2,…, P.

[0016] Furthermore, in the step S13, the multiple control points in the control point set are fitted using the Bezier curve interpolation method, and the method for forming the curve cutting path is to construct a point coordinate calculation function B(μ) of the Bezier curve at the μ parameter, and calculate multiple Bezier curve fitting points. After fitting, a curve cutting path is formed; μ is the Bessel parameter, 0≤μ≤1;

[0017] The calculation formula of the point coordinate calculation function B(μ) is as follows:

[0018] Furthermore, the S2 step includes:

[0019] S21: Find the common boundary in the product solid geometric information of the straight line segments, arcs and curves of the i-th part and the j-th part in the drawing and calculate the cutting distance E of the common boundary common-ij , the product solid geometry information set of the i-th part is R i ={G i1 ,G i2 ,…,G iI}; The product solid geometry information set of the j-th part is R j ={G j1 ,G j2 ,…,G jJ};G i and G j For the j-th part and the j-th part respectively, I and J are the total number of product three-dimensional geometric information of the i-th part and the j-th part respectively;

[0020] S22: Optimize and calculate the cutting path of the i-th part i :

[0021] G ih The product solid geometry information set of the i-th part is R i The h-th product solid geometry information in ‖G i1 -G ih ‖2 is the normalized distance between the first product solid geometry information of the i-th part and the h-th product solid geometry information; Line(G ih ) is the product solid geometry information set of the i-th part R i The calculation function of the cutting path distance of the h-th product solid geometric information;

[0022] S23: Traverse the S22 step for all parts in the product to obtain a cutting path for each part;

[0023] S24: Merge the cutting paths between the multiple parts of the product to obtain the total cutting path distance Path of the product: Where k is the total number of parts of the product; Path j is the cutting path of the j-th part calculated according to step S22.

[0024] Furthermore, in step S21, the rule for determining that the common boundary of the product is a straight line segment is that if the direction vectors of two straight line segments on the plane are the same and there is a section of overlap, then these two straight line segments are the common boundary in the three-dimensional geometric information of the product in the drawing;

[0025] The rule for determining that the shared boundary of a product is an arc is that the starting point, center of the circle, end point, starting angle, and end angle parameters of the two arcs are the same;

[0026] The rule for determining that the common boundary of the products is a curve is that the overlap of the control points in the two curves is more than 70%, and the Bezier curve interpolation weights of the two curves at the same control points are the same.

[0027] Furthermore, in the step S22, when G ih When it is a straight line segment, Line(G ih ) is calculated as follows:

[0028] ∈ is the weight for calculating the distance between the straight line segment cutting path, 0≤∈≤1; are the horizontal and vertical coordinates of the starting point of the h-th line segment respectively; is the end point of the hth straight line segment;

[0029] When G ih For arc: in, Calculate the weight for the arc cutting path distance, r h is the radius of the circle where the hth arc lies, and are the starting angle and ending angle of the hth arc relative to the cutting plane point (x0, y0);

[0030] When G ih For a curve:

[0031] Furthermore, the optimal laser emission power calculation model during the cutting process constructed in step S3 is as follows:

[0032]

[0033] Wherein, Q(x, y, t) is the energy absorbed by the surface of the cut material for melting or vaporization, (x0, y0) is the coordinate of the initial position of the laser cutting point, (x(t), y(t)) is the coordinate of the real-time position of the cutting path planned in step S2, η is the absorption efficiency of the cut material to the laser energy emitted by the laser cutting head; ω is the radius of the laser beam;

[0034] Among them, Q loss The energy emitted by the laser is lost on the surface of the cut material; A is the laser spot area formed by the laser on the surface of the material being cut, T(x(t), y(t)) is the surface temperature of the material being cut obtained by real-time monitoring, is the temperature gradient along the thickness direction; δ is the thermal conductivity of the material;

[0035] Where λ is the laser wavelength; D is the laser beam diameter before focusing, D = 2ω; K is the beam quality parameter.

[0036] The present invention also provides a control system for a laser cutting head using the above method, the system comprising a position monitoring sensor and a temperature sensor, the position monitoring sensor being used to monitor the real-time position of the laser cutting head, and the temperature sensor being used to monitor the surface temperature of the material being cut in real time; the system further comprising a product drawing information acquisition module, a cutting path planning module, an optimal laser emission power calculation module, and a control module;

[0037] The product drawing information acquisition module is used to obtain the CAD drawing of the desired cut three-dimensional product and extract the three-dimensional geometric information of the product including the straight line segments, circular arcs and curves in the drawing;

[0038] The cutting path planning module is used to plan the laser cutting path;

[0039] The optimal laser emission power calculation module monitors the surface temperature of the material being cut and the real-time position of the laser cutting head in real time, and constructs an optimal laser power calculation model during the laser cutting process;

[0040] The control module controls the laser cutting head to cut the material to be cut according to the cutting path planned by the cutting path planning module, and controls the real-time laser emission power of the laser cutting head according to the optimal real-time laser power calculated by the optimal laser emission power calculation module.

[0041] This invention converts the workpiece shape to be cut into information understandable by the CNC system. Based on this input, the CNC system generates pulse commands, which drive a motor to control the worktable carrying the laser cutting head. This continuous feed forces the laser beam to perform continuous cutting, allowing for the arbitrary processing of both flat and curved surfaces without the need for a mold. This integrated solution will enable more efficient process optimization and provide an intelligent, highly flexible solution for laser cutting.

[0042] Compared with the traditional optimization method based on the mechanism model, the present invention adopts the cutting path planning of the laser cutting head based on the product drawing to be obtained. It is a technical solution based on data-driven laser cutting head, which can better adapt to the nonlinear relationship between complex process parameters and quality, and can provide more accurate prediction capabilities, providing reliable guidance and optimization solutions for laser cutting processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention will be described in more detail below based on embodiments and with reference to the accompanying drawings, wherein:

[0044] Figure 1 Schematic diagram of a control method for a laser cutting head according to an embodiment of the present invention;

[0045] Figure 2 A line graph comparing the optimization of the real-time travel path and emission power of the laser cutting head using the method of the present invention and not using the method of the present invention;

[0046] Figure 3 Schematic diagram of a control system of a laser cutting head in an embodiment of the present invention;

[0047] Figure 4 Schematic diagram of the structure of a laser cutting machine using the method of the present invention in an embodiment of the present invention;

[0048] Figure 5 for Figure 4 A magnified view of part A in FIG;

[0049] Figure 6 This is a structural schematic diagram from another perspective of a laser cutting machine using the method of the present invention in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention fall within the scope of protection of the present invention.

[0051] The present invention provides a control method for a laser cutting head, which optimizes the travel path of the laser cutting head and the laser emission power during the cutting process in real time. Figure 1As shown, the method includes the following steps:

[0052] S1: Obtain the CAD drawing of the desired three-dimensional product to be cut, and extract the product's three-dimensional geometric information, including the line segments, arcs, and curves in the drawing. Generally, the product's three-dimensional geometric information includes geometric information such as the product's boundaries (such as internal contours of holes and slots), line segments, arcs, or curves. The extracted geometric information defines the object to be cut and is the basis for path planning. CAD drawings are usually 2D plan views in formats such as DXF or DWG. This step is to import them into the control software of the laser cutting machine.

[0053] S2: perform laser cutting path planning;

[0054] S3: Control the laser cutting head to move in real time according to the cutting path planned in step S2, monitor the working environment temperature of the laser cutting head and the surface temperature of the cut material in real time, and build a calculation model for the optimal laser emission power during the laser cutting process;

[0055] S4: Control the real-time laser emission power of the laser cutting head according to the optimal real-time laser power calculated in step S3.

[0056] Laser cutting path planning is one of the key steps in the laser cutting process. It ensures that the cutting machine performs cutting operations in the required order and path, thereby obtaining a product that meets the design requirements. Based on the CAD drawing of the model to be cut, it is necessary to separately calculate the path distance of the product's three-dimensional geometric information such as straight line segments, arcs, and curves in the CAD drawing. Therefore, as a preferred embodiment of the present invention, step S1 includes:

[0057] S11: Get the starting and ending coordinates of multiple straight line segments for each part:

[0058] L n is the nth straight line segment of the drawing, is the starting point coordinate of the nth line segment, are the horizontal and vertical coordinates of the starting point of the nth straight line segment respectively; is the end point of the nth straight line segment, are the abscissa and ordinate of the end point of the nth straight line segment; n = 1, 2, ..., N;

[0059] S12: Get the geometric information of multiple arcs of each part of the product:

[0060] C m is the mth arc in the drawing, is the coordinate of the center of the circle where the mth arc is located, are the horizontal and vertical coordinates of the center of the circle where the mth arc is located; r m is the radius of the circle where the mth arc lies, are the starting angle and ending angle of the starting point and ending point of the mth arc relative to the center of the circle, that is, is the starting point of the mth arc With the center The angle between the connecting line and the x-axis of the cutting plane, is the end point of the mth arc With the center The angle between the connecting line and the x-axis of the cutting plane is m = 1, 2, ..., M; and

[0061] S13: Obtaining coordinates of control points in multiple curves of each part of the product, forming a control point set for each curve, and fitting multiple control points in the control point set using a Bezier curve interpolation method to form a curve cutting path; Among them, C p is the set of control points of the p-th curve, is the qth control point of the pth curve, and its coordinates on the cutting plane are Q is the total number of control points of the p-th curve, p = 1, 2,…, P.

[0062] In step S13, the Bezier curve interpolation method is used to fit multiple control points in the control point set. The method of forming the curve cutting path is to construct a point coordinate calculation function B(μ) of the Bezier curve at the μ parameter, and calculate multiple Bezier curve fitting points After fitting, a curve cutting path is formed; μ is a Bessel parameter, 0≤μ≤1, preferably, μ=0.67;

[0063] The calculation formula of the point coordinate calculation function B(μ) is as follows: The calculation result of B(μ) is a point coordinate: and are the horizontal and vertical coordinates of the point at the μ parameter of the pth curve respectively; multiple After fitting, a curve cutting path is formed.

[0064] Assume that after the product CAD drawing is imported, only one curve is obtained. In step S13, P = 1. When fitting a curve, there are three control points c0, c1, and c2, whose coordinates in the cutting plane are (0,0), (1,2), and (2,0), respectively. The point coordinate calculation function for fitting the three control points using the Bezier curve is:

[0065]

[0066] When μ=0.5, the coordinates of the points in the final control walking path of the Bezier curve fitting are the calculation results of B(0.5). Substituting 0.5 into the above formula,

[0067]

[0068] The coordinates of the point in the final control walking path obtained by Bezier curve fitting when μ=0.5 are (1,1).

[0069] The application of Bezier curve can perform curve fitting and interpolation according to several known control points. Based on the number of control points and the parameter μ, the smooth points on the cutting curve walking path of the laser cutting head can be finally fitted to achieve accurate planning of the walking path of the laser cutting head.

[0070] Laser cutting path planning is one of the key steps in the laser cutting process. It ensures that the cutting machine performs cutting operations in the required order and path, thereby obtaining a product that meets the design requirements. Laser cutting path planning is to ensure efficient and accurate completion of the cutting task by optimizing the movement trajectory and cutting sequence of the laser head. Path planning generates cutting paths based on the geometric information of the CAD drawing and reduces problems such as idle travel and material deformation through optimization algorithms. Therefore, it is necessary to clarify how to plan the shortest laser cutting path when situations such as shared boundaries occur. Therefore, as another preferred embodiment of the present invention, step S2 includes:

[0071] S21: Find the common boundary in the product solid geometry information of the straight line segments, arcs and curves of the i-th part and the j-th part in the drawing and calculate the common boundary cutting distance E common-ij , the i-th part is composed of multiple straight line segments, arcs and curves, and the product three-dimensional geometric information set of the i-th part is R i ={G i1 ,G i2 ,…,G iI}; The product solid geometry information set of the jth part is R j ={G j1 ,G j2 ,…,G jJ};G i and G j I and J are the total number of product three-dimensional geometric information of the j-th part and the j-th part respectively, that is, the i-th part and the j-th part are sequentially obtained through steps S11-S13 to obtain the respective information sets of straight line segments, circular arcs and curves, and then the three information sets of each part are further merged to obtain R i and R j ;

[0072] S22: Optimize and calculate the cutting path of the i-th part i :

[0073] G ih The product solid geometry information set of the i-th part is R i The h-th product solid geometry information in ‖G i1 -G ih ‖2 is the normalized distance between the first product solid geometry information of the i-th part and the h-th product solid geometry information, that is, the cutting path distance between the last cutting point of the first product solid geometry information and the first cutting point of the h-th product solid geometry information; Line(G ih ) is the product solid geometry information set of the i-th part R i The calculation function of the cutting path distance of the h-th product solid geometric information;

[0074] S23: Traverse step S22 for all parts in the product to obtain the cutting path of each part;

[0075] S24: Merge the cutting paths between multiple parts of the product to obtain the total cutting path distance Path of the product:

[0076]

[0077] Where k is the total number of parts of the product; Path j is the cutting path of the jth part calculated according to step S22. k! is the factorial of k. Similarly, 2! and (k-2)! are also factorial calculations.

[0078] In step S21, the rule for determining whether the common boundary of the product is a straight line segment is that if the direction vectors of two straight line segments on the plane are the same and there is a section of overlap, then these two straight line segments are the common boundary in the solid geometric information of the product in the drawing;

[0079] The rule for determining that the shared boundary of a product is an arc is that the starting point, center of the circle, end point, starting angle, and end angle parameters of the two arcs are the same;

[0080] The rule for determining that the common boundary of the products is a curve is that the overlap of the control points in the two curves is more than 70%, and the Bezier curve interpolation weights of the two curves at the same control points are the same.

[0081] Regarding the rules for selecting the cutting direction and starting point, in the actual cutting process, it is necessary not only to determine the cutting order of the common edges, but also to select the cutting direction and starting point of each edge. In order to avoid material deformation or deviation of the common edges during cutting, the following strategies are often adopted:

[0082] 1) Internal priority cutting: Cut the inner contour first, then the outer contour, to ensure that the parts will not loosen during the cutting process.

[0083] 2) Common edge priority cutting: Prioritize cutting the common edge to reduce deformation or material warping caused by thermal stress.

[0084] 3) Starting point selection: The selection of the cutting starting point can be based on the geometric characteristics of the part. Usually the path closest to the starting point is selected as the starting point.

[0085] Furthermore, for different types of product stereoscopic geometric information, the path calculation formula is also different. In step S22, when G ih When it is a straight line segment, it is calculated as follows:

[0086] ∈ is the weight for calculating the distance between the straight line segment cutting path, 0≤∈≤1, preferably, ∈=0.35; are the horizontal and vertical coordinates of the starting point of the h-th line segment respectively; is the end point of the hth straight line segment;

[0087] When G ih For arc:

[0088] in, Calculate the weight for the arc cutting path distance, Preferably, r h is the radius of the circle where the hth arc lies, and are the starting angle and ending angle of the hth arc relative to the cutting plane point (x0, y0);

[0089] When G ih When it is a curve, the product solid geometric information set of the i-th part is R i When the h-th product solid geometry information in is a curve,:

[0090]

[0091] During the laser cutting process, the laser beam inputs heat into the material surface, causing the material to melt or vaporize, ultimately achieving cutting. Since heat is irradiated on the material surface by the laser and diffuses into the material through conduction, it is crucial to accurately analyze the temperature field formed on the material surface by the laser emission power. During the laser cutting process, the laser beam is regarded as a moving heat source, and its power density distribution can be represented by a Gaussian function. Therefore, as another preferred embodiment of the present invention, the optimal laser emission power calculation model for the cutting process constructed in step S3 is as follows:

[0092]

[0093] Where Q(x, y, t) is the energy absorbed by the surface of the cut material for melting or vaporization, (x0, y0) is the coordinate of the initial point of laser cutting, (x(t), y(t)) is the coordinate of the real-time position of the cutting path planned in step S2, η is the absorption efficiency of the cut material to the laser energy emitted by the laser cutting head; ω is the radius of the laser beam;

[0094] Among them, Q loss The energy emitted by the laser is lost on the surface of the cut material; A is the laser spot area formed by the laser on the surface of the material being cut, T(x(t), y(t)) is the surface temperature of the material being cut obtained by real-time monitoring, is the temperature gradient along the thickness direction, indicating the rate of heat transfer to the material under review; δ is the thermal conductivity of the material, in W / (m·K), which can be obtained by looking up the table according to different cutting materials;

[0095]

[0096] Wherein, λ is the laser wavelength, λ = 1064 nm; D is the laser beam diameter before focusing, D = 2ω; K is the beam quality parameter, K = 1.1 to 1.3.

[0097] The model of the laser cutting machine is 3015, the laser emission power range is between 500w-2000w, it uses a fiber laser source, and the emitted laser wavelength λ=1064nm, ω=10mm~15mm;

[0098] During the laser cutting process, the laser beam inputs heat into the surface of the material, causing the material to melt or vaporize, ultimately achieving cutting. Since heat is irradiated on the surface of the material by the laser and diffuses into the interior of the material by conduction, it is crucial to accurately analyze the temperature field of the material. By establishing a laser energy loss function related to the temperature field of the material being cut, the absorption efficiency of the laser emission power of the material being cut can be clarified, thereby improving the accuracy of the calculation of the optimal real-time laser emission power. The calculation of the temperature distribution during the laser cutting process by the present invention provides an accurate simulation tool for the calculation of the optimal real-time laser emission power. Through the finite element discretization and numerical solution of the heat conduction equation, the material temperature field distribution caused by the laser heat source can be simulated, thereby optimizing the cutting parameters, such as laser power, cutting speed, etc. In practical applications, it is also necessary to combine the physical properties of the material, phase change effects and boundary conditions for more accurate simulation.

[0099] Fiber laser cutting machines are often used to cut metal materials. The focal length f of the lens mainly depends on the thickness of the material and the required cutting accuracy. Generally speaking, different types of fiber laser cutting machines are used for different materials to be cut, and the focal length range of fiber laser cutting machines is also different, as follows:

[0100] A) Short focal length lens: f = 100mm ~ 125mm, suitable for thin plate cutting (such as 1-3mm thick stainless steel, aluminum, copper, etc.), with high focusing accuracy, narrow cutting slit, suitable for fine cutting.

[0101] B) Medium focal length lens: f = 150mm ~ 200mm, suitable for cutting medium and thick plates (such as 3-10mm carbon steel, stainless steel, etc.).

[0102] C) Long focal length lens: f = 200mm ~ 250mm, suitable for thick plate cutting (such as steel plates thicker than 10mm), with a large focal depth, suitable for cutting tasks requiring large laser energy.

[0103] like Figure 2 As shown, the blue line represents the real-time transmission power and temperature of the cutting point controlled by the method provided by the present invention for the laser cutting head, and the red line is the real-time transmission power and temperature change line chart when the real-time transmission power and walking path of the laser cutting head are not controlled by the method provided by the present invention. Figure 2 It can be seen that the control method and system of the laser cutting head provided by the present invention can control the laser cutting head to emit the optimal laser emission power according to the thickness requirements of the cutting position according to the different real-time walking path positions, while ensuring that the temperature field is evenly distributed and not too high, so that the power does not need to be provided too high at all times to waste energy, while ensuring the cutting accuracy.

[0104] The present invention also provides a control system for a laser cutting head using the above method, such as Figure 3 As shown, the system includes a position monitoring sensor and a temperature sensor. The position monitoring sensor is used to monitor the real-time position of the laser cutting head, and the temperature sensor is used to monitor the surface temperature of the cut material in real time. The system also includes a product drawing information acquisition module, a cutting path planning module, an optimal laser emission power calculation module and a control module.

[0105] The product drawing information acquisition module is used to obtain the CAD drawing of the required cut three-dimensional product and extract the product three-dimensional geometric information including the straight line segments, arcs and curves in the drawing;

[0106] Cutting path planning module, used for laser cutting path planning;

[0107] The optimal laser emission power calculation module monitors the surface temperature of the material being cut and the real-time position of the laser cutting head in real time, and builds an optimal laser power calculation model during the laser cutting process;

[0108] The control module controls the laser cutting head to cut the material according to the cutting path planned by the cutting path planning module, and controls the real-time laser emission power of the laser cutting head according to the optimal real-time laser power calculated by the optimal laser emission power calculation module.

[0109] The control system of the CNC laser cutting head provided by the present invention can convert the process parameters and routes, the diameter of the light plate and the motion trajectory, the cutting parameters and the auxiliary functions into a processing program sheet in accordance with the prescribed instruction code and the relevant program format, and transmit the contents thereof in full to the control single chip microcomputer, thereby controlling the laser cutting machine to perform part processing operations. The system provided by the present invention has two-dimensional image import, automatic model calibration, normal vector following, interpolation following control, three-dimensional error judgment and corner processing, which are all core functions of the system. It can carry out automatic calibration compensation for the horizontal offset, tilt error and positioning deviation that occur during large-angle vertical following in the model, form a rounded transition path by interpolating the corner points of the arc, and fit the curve in the cutting path according to the control points by fitting the Bezier curve. The collected data point information is used to infer the three-dimensional geometric information of the cut material and the required product, thereby achieving high-precision processing. At the same time, the corner interpolation following control function of the system can also improve the overall stability of the swing mechanism, which can not only eliminate the problem of jitter at the end of the cutting head, but also avoid the risk of head collision under pure interpolation control, and enhance safety protection. The corner processing function can achieve the effect of continuous cutting by adjusting the normal vector, tangent speed and direction in the plane where the section is located in advance.

[0110] The control method of the laser cutting head provided by the present invention can be applied to various models of three-dimensional laser cutting machines in the prior art, such as the laser cutting head on a laser cutting machine disclosed in publication number CN118002934A. The product drawing information acquisition module, cutting path planning module, optimal laser emission power calculation module and control module in the control system of the present invention are arranged in the control device of the controller of the patent, and a position monitoring sensor and a temperature sensor are installed on the laser cutting machine to perform real-time laser cutting related data measurement, thereby realizing real-time control of the cutting path and laser emission power of the laser cutting head.

[0111] The control method of the laser cutting head provided by the present invention can also be applied to Figure 4-Figure 6 The laser cutting head on the laser cutting machine shown in the figure is Figure 4-Figure 6 The laser cutting machine shown includes a cutting platform 1, such as Figure 6 As shown, the cutting platform is supported by a plurality of support legs 101 symmetrically arranged on the left and right sides. A hollow plate 102 is provided on the cutting platform 1 for receiving the raw materials to be cut. Figure 4 、 Figure 6 As shown, the left and right ends of the cutting platform 1 are provided with y-axis screws 2, x-axis screws 3 connected to the y-axis screws 2 provided at the left and right ends, a z-axis laser cutting head 4 provided on the x-axis screw 3, and a z-axis motor 5 for driving the z-axis laser cutting head to move up and down. The front end of the cutting platform 1 is provided with an electrical box 6 for driving the y-axis screw 2 to rotate, thereby driving the x-axis screw 3 to move forward and backward, and an x-axis motor 7 is provided on the x-axis screw 3 to drive the x-axis screw 3 to move left and right, as shown. Figure 5 The laser cutting head 4 shown is provided with a position monitoring sensor 401 and a temperature sensor 402, and the cutting platform 1 is provided with a PLC controller 8, which is also provided with a liquid crystal display panel. The PLC controller 8 is provided with the product drawing information acquisition module, cutting path planning module, optimal laser emission power calculation module and control module setting in the control system of the laser cutting head provided by the present invention, and then the cutting path and laser emission power of the laser cutting head are controlled in real time according to the position monitoring sensor and the temperature sensor.

[0112] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0113] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

Claims

1. A method for controlling a laser cutting head, wherein the method optimizes and controls the travel path of the laser cutting head and the laser emission power during the cutting process in real time, and is characterized in that: The method comprises the following steps: S1: Obtain a CAD drawing of a desired cut 3D product, and extract 3D geometric information of the product including straight line segments, arcs, and curves in the drawing; S2: perform laser cutting path planning; S3: Controlling the laser cutting head to move in real time according to the cutting path planned in step S2, monitoring the working environment temperature of the laser cutting head and the surface temperature of the material being cut in real time, and building a calculation model for the optimal laser emission power during the laser cutting process; S4: controlling the real-time laser emission power of the laser cutting head according to the optimal real-time laser power calculated in step S3; The S1 step includes: S11: Get the starting and ending coordinates of multiple straight line segments for each part: L n is the nth straight line segment of the drawing, is the starting point coordinate of the nth straight line segment; is the end point of the nth straight line segment; n=1,2,…,N; S12: Get the geometric information of multiple arcs of each part of the product: C m is the mth arc of the drawing, is the coordinate of the center of the circle where the mth arc is located; r m is the radius of the circle where the mth arc lies, are the starting angle and ending angle of the starting point and ending point of the mth arc relative to the center of the circle; m = 1, 2, ..., M; and S13: Obtaining coordinates of control points in multiple curves of each part of the product, forming a control point set for each curve, and fitting multiple control points in the control point set using a Bezier curve interpolation method to form a curve cutting path; Among them, C p is the set of control points of the p-th curve, is the qth control point of the pth curve, and its coordinates on the cutting plane are Q is the total number of control points of the p-th curve, p = 1, 2, ..., P; In the step S13, the multiple control points in the control point set are fitted using the Bezier curve interpolation method to form a curve cutting path by constructing a point coordinate calculation function B(μ) of the Bezier curve at the μ parameter, and calculating multiple Bezier curve fitting points. After fitting, a curve cutting path is formed; μ is the Bessel parameter, 0≤μ≤1; The calculation formula of the point coordinate calculation function B(μ) is as follows: The optimal laser emission power calculation model during the cutting process constructed in step S3 is as follows: Wherein, Q(x, y, t) is the energy absorbed by the surface of the cut material for melting or vaporization, (x0, y0) is the coordinate of the initial position of the laser cutting point, (x(t), y(t)) is the coordinate of the real-time position of the cutting path planned in step S2, η is the absorption efficiency of the cut material to the laser energy emitted by the laser cutting head; ω is the radius of the laser beam; Among them, Q loss The energy emitted by the laser is lost on the surface of the cut material; A is the laser spot area formed by the laser on the surface of the material being cut, T(x(t), y(t)) is the surface temperature of the material being cut obtained by real-time monitoring, is the temperature gradient along the thickness direction; δ is the thermal conductivity of the material; Where λ is the laser wavelength; D is the laser beam diameter before focusing, D = 2ω; K is the beam quality parameter.

2. The control method of the laser cutting head according to claim 1, characterized in that: The S2 step includes: S21: Find the common boundary in the product solid geometric information of the straight line segments, arcs and curves of the i-th part and the j-th part in the drawing and calculate the cutting distance E of the common boundary common-ij , the product solid geometry information set of the i-th part is R i ={G i1 ,G i2 ,…,G iI }; The product solid geometry information set of the j-th part is R j ={G j1 ,G j2 ,…,G jJ };G i and G j For the j-th part and the j-th part respectively, I and J are the total number of product three-dimensional geometric information of the i-th part and the j-th part respectively; S22: Optimize and calculate the cutting path of the i-th part i : G ih The product solid geometry information set of the i-th part is R i The h-th product solid geometry information in ‖G i1 -G ih ‖2 is the normalized distance between the first product solid geometry information of the i-th part and the h-th product solid geometry information; Line(G ih ) is the product solid geometry information set of the i-th part R i The calculation function of the cutting path distance of the h-th product solid geometric information; S23: Traverse the S22 step for all parts in the product to obtain a cutting path for each part; S24: Merge the cutting paths between the multiple parts of the product to obtain the total cutting path distance Path of the product: Where k is the total number of parts of the product; Path j is the cutting path of the j-th part calculated according to step S22.

3. The control method of the laser cutting head according to claim 2, characterized in that: In step S21, the rule for determining that the common boundary of the product is a straight line segment is that if the direction vectors of two straight line segments on the plane are the same and there is a section of overlap, then these two straight line segments are the common boundary in the three-dimensional geometric information of the product in the drawing; The rule for determining that the shared boundary of a product is an arc is that the starting point, center of the circle, end point, starting angle, and end angle parameters of the two arcs are the same; The rule for determining that the common boundary of the products is a curve is that the overlap of the control points in the two curves is more than 70%, and the Bezier curve interpolation weights of the two curves at the same control points are the same.

4. The control method of the laser cutting head according to claim 2, characterized in that: In the step S22, when G ih When it is a straight line segment, Line(G ih ) is calculated as follows: ∈ is the weight for calculating the distance between the straight line segment cutting path, 0≤∈≤1; are the horizontal and vertical coordinates of the starting point of the h-th line segment respectively; is the end point of the hth straight line segment; When G ih For arc: in, Calculate the weight for the arc cutting path distance, r h is the radius of the circle where the hth arc lies, and are the starting angle and ending angle of the hth arc relative to the cutting plane point (x0, y0); When G ih For a curve:

5. A control system for a laser cutting head using the method according to any one of claims 1 to 4, wherein the system comprises a position monitoring sensor and a temperature sensor, wherein the position monitoring sensor is used to monitor the real-time position of the laser cutting head, and the temperature sensor is used to monitor the surface temperature of the material being cut in real time; characterized in that: The system also includes a product drawing information acquisition module, a cutting path planning module, an optimal laser emission power calculation module and a control module; The product drawing information acquisition module is used to obtain the CAD drawing of the desired cut three-dimensional product and extract the three-dimensional geometric information of the product including the straight line segments, arcs and curves in the drawing; The cutting path planning module is used to plan the laser cutting path; The optimal laser emission power calculation module monitors the surface temperature of the material being cut and the real-time position of the laser cutting head in real time, and constructs an optimal laser power calculation model during the laser cutting process; The control module controls the laser cutting head to cut the material to be cut according to the cutting path planned by the cutting path planning module, and controls the real-time laser emission power of the laser cutting head according to the optimal real-time laser power calculated by the optimal laser emission power calculation module.

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