Control system and method of laser cutting head

Abstract

The invention provides a control method of a laser cutting head, which comprises the following steps of: acquiring a CAD drawing of a to-be-obtained cutting three-dimensional product, and extracting product three-dimensional geometric information including a straight line segment, an arc and a curve of the drawing from the CAD drawing; a laser cutting path is planned; the laser cutting head is controlled to walk in real time according to the planned cutting path, the working environment temperature of the laser cutting head and the surface temperature of the cut material are monitored in real time, and an optimal laser emission power calculation model in the laser cutting process is constructed; and controlling the real-time laser emission power of the laser cutting head according to the calculated optimal real-time laser power. Compared with a traditional optimization method based on a mechanism model, the method has the advantages that cutting path planning of the laser cutting head is conducted based on the obtained product drawing, the method can better adapt to the nonlinear relation between complex technological parameters and quality, more accurate prediction capacity is provided, and the method is suitable for large-scale popularization and application. And a reliable guidance and optimization scheme is provided for laser cutting processing.

Description

Technical Field

[0001] The 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 industry, the application advantages of laser cutting technology in it have become increasingly prominent. Laser cutting technology is to irradiate the material to be cut with a high-power density laser beam, so that the material is quickly vaporized, ablated, melted or reaches the ignition point, and evaporates to form tiny holes. At the same time, the molten material is blown away with the help of auxiliary high-pressure gas coaxial with the laser beam. As the laser beam moves, the holes continuously form a very narrow slit, thereby completing the cutting of the processed material. Using laser cutting technology to cut materials has the advantages of good cutting quality, high cutting efficiency, fast cutting speed, no need to contact the processed material, and strong applicability.

[0003] In the prior art, for example, the Chinese patent application document with application number CN202210090898.0 discloses a control method and related equipment for laser cutting; the 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 the first path for one cycle after responding to the laser cutting instruction, and then controls the laser beam to perform laser cutting along the 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 cutting of the product to be cut is completed. However, it is not clear how to plan the shortest laser cutting path according to the different product graphics to be obtained, and how to perform corner interpolation at positions with rounded corners or turns to avoid the occurrence of burrs and the like, and 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] In view of the above-mentioned defects, the present invention provides a control system and method for a laser cutting head. The path planning of laser cutting of the present invention generates a cutting path based on the geometric information of the CAD drawing, optimizes the movement trajectory and cutting sequence of the laser head, and calculates the optimal real-time laser emission power based on the temperature field distribution analysis of the planned path, effectively ensuring that the cutting task is completed efficiently and accurately.

[0005] The present invention provides the following technical solution: a control method for a laser cutting head, the method performs real-time optimization control on the walking path of the laser cutting head and the laser emission power during the cutting process, the method comprising the following steps:

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

[0007] S2: Perform laser cutting path planning;

[0008] 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 material being cut in real time, and build an optimal laser emission power calculation model during the laser cutting process;

[0009] 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.

[0010] Furthermore, the S1 step includes:

[0011] S11: Get the starting and ending coordinates of multiple straight line segments of 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 pth curve, p = 1, 2,…, P.

[0016] Furthermore, in the step S13, the Bezier curve interpolation method is used to fit the multiple control points in the control point set, 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 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 three-dimensional geometric information set of the i-th part is R i = {G i1 ,G i2 ,…,G il}; The product three-dimensional geometric information set of the j-th 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 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 step S22 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; P j is the cutting path of the jth part calculated according to step S22.

[0024] Furthermore, in the 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 the 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 the products is an arc is that the parameter information of the starting point, the center of the circle, the ending point, the starting angle and the ending angle 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 abscissa and ordinate of the starting point of the h-th straight 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 curves:

[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 position coordinate of the initial point of laser cutting, (x(t), y(t)) is the real-time position coordinate of the cutting according to 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 It is the energy emitted by the laser that is lost on the surface of the material being cut; 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] Wherein, 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 method described above, 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 in real time, and the temperature sensor being used to monitor the surface temperature of the cut material in real time; the system also comprises 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 acquire the CAD drawing of the cut three-dimensional product to be obtained, and extract the three-dimensional geometric information of the product including the straight line segments, arcs and curves of 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] The present invention can convert the shape of the workpiece product to be cut into information that can be understood by the numerical control system. The numerical control system gives corresponding pulse instructions based on the input information, controls the operation of the workbench carrying the laser cutting head through the driving motor, and promotes the laser beam to perform continuous cutting through continuous feeding, so that plane graphics and spatial curved surface parts can be processed at will without molds. Such an integrated solution will achieve more efficient process optimization and provide an intelligent and highly flexible solution for laser cutting processing.

[0042] Compared with the traditional optimization method based on mechanism model, the present invention adopts the cutting path planning of 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 ability, providing reliable guidance and optimization scheme 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 is a schematic diagram of a control method for a laser cutting head according to an embodiment of the present invention;

[0045] Figure 2 A line chart comparing the optimization of the real-time walking path and the 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 A 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 schematic structural 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 is further described below in conjunction with 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 belong to the protection scope of the present invention.

[0051] The present invention provides a control method for a laser cutting head, which performs real-time optimization control on the walking path of the laser cutting head and the laser emission power during the cutting process. Figure 1As shown, the method comprises the following steps:

[0052] S1: Obtain the CAD drawing of the three-dimensional product to be cut, and extract the three-dimensional geometric information of the product including the straight line segments, arcs and curves in the drawing; the three-dimensional geometric information of the product generally includes geometric information such as the boundary of the product (such as the internal contour of the hole, groove, etc.), straight line segments, arcs or curves. The extracted geometric information defines the object to be cut and is the basis of path planning. The CAD drawing is usually a 2D plane drawing in a format such as DXF or DWG. This step is to import it 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, which ensures that the cutting machine performs the cutting operation in the required order and path, so as to obtain a product that meets the design requirements. According to the CAD drawing of the model to be cut, it is necessary to calculate the path distance of the product three-dimensional geometric information of the straight line segment, arc, curve, etc. in the CAD drawing separately. 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 of each part:

[0058] L n is the nth straight line segment of the drawing, is the starting point coordinate of the nth straight 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 of 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; 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 pth 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 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 a Bessel parameter, 0≤μ≤1, preferably, μ=0.67;

[0063] The calculation formula of 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] Assuming that after the CAD drawing of the product is imported, only one curve is obtained, then P=1 in step S13. 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. Then, 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 points in the final control walking path obtained by the Bezier curve fitting when μ=0.5 are (1,1).

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

[0070] Laser cutting path planning is one of the key steps in the laser cutting process. It ensures that the cutting machine performs the cutting operation in the required order and path, so as to obtain a product that meets the design requirements. Laser cutting path planning is to optimize the movement trajectory and cutting sequence of the laser head to ensure efficient and accurate completion of the cutting task. Path planning generates a cutting path based on the geometric information of the CAD drawing, and reduces problems such as empty travel and material deformation through optimization algorithms. Therefore, it is necessary to clarify how to plan the shortest laser cutting path when shared boundaries and other situations 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 are 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, 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, arcs and curves, and then the three information sets of each part are further combined 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; P 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 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 the two straight line segments are the common boundary in the three-dimensional geometric information of the product in the drawing;

[0079] The rule for determining that the shared boundary of the products is an arc is that the parameter information of the starting point, the center of the circle, the ending point, the starting angle and the ending angle 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 used:

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

[0083] 2) Common edge priority cutting: Prioritize cutting of common boundaries 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 abscissa and ordinate of the starting point of the h-th straight 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 three-dimensional 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, and finally achieves cutting. Since the 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 by the laser emission power on the material surface. 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 in the cutting process constructed in step S3 is as follows:

[0092]

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

[0094] Among them, Q loss It is the energy emitted by the laser that is lost on the surface of the material being cut; 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 examination; δ is the thermal conductivity of the material, in units of 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=1064nm; D is the laser beam diameter before focusing, D=2ω; K is the beam quality parameter, K=1.1~1.3.

[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, and finally achieving cutting. Since heat is irradiated on the surface of the material by the laser and diffused 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 cut material, the absorption efficiency of the cut material to the laser emission power can be clarified, thereby improving the calculation accuracy of the optimal real-time laser emission power. The present invention provides an accurate simulation tool for the calculation of the optimal real-time laser emission power through the calculation of the temperature distribution during the laser cutting process. 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 requirements for cutting accuracy. Generally speaking, the types of fiber laser cutting machines used are different for different materials to be cut, and the focal length range of the fiber laser cutting machine 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 larger laser energy.

[0103] like Figure 2 As shown, the blue line represents the real-time transmission power and the 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 the 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 requirement of the cutting position according to the different positions of the path it is walking in real time, while ensuring that the temperature field is evenly distributed and not too high. Therefore, 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 in real time, 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 three-dimensional geometric information of the product 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 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.

[0109] The control system of the numerical control 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 according to the specified instruction code and the relevant program format, and transmit the contents thereof to the control single chip in full, so as to control the laser cutting machine to perform the part processing operation. The system provided by the present invention has two-dimensional graph import, automatic model calibration, normal vector following, interpolation following control, three-dimensional error judgment and corner processing, which are the core functions of the system, and can carry out automatic calibration compensation for the horizontal offset, tilt error and positioning deviation occurring during large-angle vertical following in the model, form a rounded transition path through the corner point interpolation of the arc, and fit the curve in the cutting path according to the control point through the Bezier curve fitting method, and use the collected data point information to infer the three-dimensional geometric information of the cut material and the required product, so as to achieve high-precision processing. At the same time, the corner point 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 strengthen 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 types of three-dimensional laser cutting machines in the prior art, such as a 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 4 of the patent, and a position monitoring sensor and a temperature sensor are installed on the laser cutting machine 8 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 comprises a cutting platform 1, such as Figure 6 As shown, the cutting platform is supported by a plurality of supporting feet 101 symmetrically arranged on the left and right sides, and a hollow plate 102 is arranged 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 arranged at the left and right ends, a z-axis laser cutting head 4 arranged 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 and then 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 in FIG. 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, and the PLC controller 8 is also provided with a liquid crystal display panel. The PLC controller 8 is provided with a product drawing information acquisition module, a cutting path planning module, an optimal laser emission power calculation module and a 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 may be provided as methods, systems, or computer program products. Therefore, the present application may 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 may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include 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 generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. 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 control method for a laser cutting head, wherein the method performs real-time optimization control on the walking path of the laser cutting head and the laser emission power during the cutting process, and is characterized in that: The method comprises the following steps: S1: Obtain a CAD drawing of a desired cut three-dimensional product, and extract three-dimensional geometric information of the product including straight line segments, arcs and curves in the drawing; S2: Perform laser cutting path planning; 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 material being cut in real time, and build an optimal laser emission power calculation model 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.

2. The laser head control method according to claim 1, characterized in that: The S1 step includes: S11: Get the starting and ending coordinates of multiple straight line segments of 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 pth curve, p = 1, 2,…, P.

3. The control method of the laser cutting head according to claim 2, characterized in that: In the step S13, the Bezier curve interpolation method is used to fit the multiple control points in the control point set, 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; The calculation formula of point coordinate calculation function B(μ) is as follows:

4. The control method of the laser cutting head according to claim 2, 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 three-dimensional geometric information set of the i-th part is R i = {G i1 ,G i2 ,…,G iI }; The product three-dimensional geometric information set of the j-th 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 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 step S22 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; P j is the cutting path of the jth part calculated according to step S22.

5. The control method of the laser cutting head according to claim 4, characterized in that: In the 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 the 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 the products is an arc is that the parameter information of the starting point, the center of the circle, the ending point, the starting angle and the ending angle 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.

6. The control method of the laser cutting head according to claim 4, 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 abscissa and ordinate of the starting point of the h-th straight 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 curves:

7. The control method of the laser cutting head according to claim 1, characterized in that: 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 position coordinate of the initial point of laser cutting, (x(t), y(t)) is the real-time position coordinate of the cutting according to 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 It is the energy emitted by the laser that is lost on the surface of the material being cut; 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; Wherein, λ is the laser wavelength; D is the laser beam diameter before focusing, D=2ω; K is the beam quality parameter.

8. A control system for a laser cutting head using the method according to any one of claims 1 to 7, 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 in real time, 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 acquire the CAD drawing of the cut three-dimensional product to be obtained, and extract the three-dimensional geometric information of the product including the straight line segments, arcs and curves of 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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