A method for analyzing the curved surface profile of laser multi-axis linkage machining and a machine tool

Abstract

The present application provides a method and a machine tool for analyzing the curved surface contour of laser multi-axis linkage machining, including the steps of: determining a first discrete step length and a second discrete step length based on laser machining parameters and multi-axis motion parameters; obtaining the digital curved surface of the product to be machined, discretizing the digital curved surface into projection curves according to the first discrete step length, and discretely analyzing the projection curves into a plurality of position points according to the second discrete step length; obtaining the first position information of each position point in the product coordinate system, and converting the first position information into the second position information in the moving platform coordinate system; and performing path planning for multi-axis linkage motion control according to the second position information. The problem that in the prior art, due to the limitations of the characteristics of the laser machining parameters themselves and the particularity of the hardware carrier parameters of multi-axis motion, it is not suitable for machining complex curved surfaces is solved.

Description

Technical Field

[0001] The present application relates to the technical field of laser processing, and particularly relates to a method for analyzing the curved surface profile of laser multi-axis linkage processing and a machine tool. Background Art

[0002] The improvement of technology and the quality of life have promoted the evolution of existing products in terms of function and appearance towards being more diverse and more refined, thereby also driving the gradual increase in the processing complexity of a single product. In the process of manufacturing complex surfaces, multi-axis linkage processing has emerged. Due to its extremely high compatibility in material selection and efficient and precise processing characteristics for various material types, laser processing has been widely used in the field of material processing. However, due to the unidirectionality of lasers and the characteristics of high energy density, it has been unable to expand the actual application on a large scale in the field of complex curved surface processing. Therefore, the organic combination of multi-axis linkage processing and laser processing can not only greatly liberate the excellent characteristics of laser processing but also broaden the application field of multi-axis linkage control processing.

[0003] However, due to the limitations of the parameter characteristics of laser processing itself and the specificity of the hardware carrier parameters of multi-axis motion, there will be potential problems of setting conflicts and mutual interference in the actual application process. Therefore, existing laser processing is usually applicable to planar laser engraving, etc., and is not suitable for the processing of complex curved surfaces.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] In view of the above deficiencies of the existing technology, the purpose of the present application is to provide a method for analyzing the curved surface profile of laser multi-axis linkage processing and a machine tool, which solves the problem that the existing technology is not suitable for the processing of complex curved surfaces due to the limitations of the parameter characteristics of laser processing itself and the specificity of the hardware carrier parameters of multi-axis motion.

[0006] On the one hand, the present application provides a method for analyzing the curved surface profile of laser multi-axis linkage processing, including the steps of:

[0007] Determine a first discrete step size and a second discrete step size based on laser processing parameters and multi-axis motion parameters;

[0008] Obtain the digital curved surface of the product to be processed, discretize the digital curved surface into projection curves according to the first discrete step size, and discretely analyze the projection curves into a number of position points according to the second discrete step size;

[0009] Obtain the first position information of each position point in the product coordinate system, and convert the first position information into the second position information in the motion platform coordinate system;

[0010] Perform path planning for multi-axis linkage motion control according to the second position information.

[0011] Optionally, the step of determining the first discrete step length and the second discrete step length based on the laser processing parameters and the multi-axis motion parameters includes:

[0012] Compare the maximum values according to the minimum spot radius r0 of the laser processing and the minimum movement accuracy m0 of the multi-axis motion. According to the maximum value comparison result, determine the first discrete step length l1,

[0013] where: l1≥max{r0,m0};

[0014] Or,

[0015] Compare the maximum values according to the minimum spot radius r0 of the laser processing, the minimum movement accuracy m0 of the multi-axis motion, and the scanning recognition accuracy error δ0 of the 3D scanning. According to the maximum value comparison result, determine the first discrete step length l1,

[0016] where: l1≥max{r0,m0,δ0}.

[0017] Optionally, the step of determining the first discrete step length and the second discrete step length based on the laser processing parameters and the multi-axis motion parameters further includes:

[0018] According to the pulse frequency f0 of the laser processing, the multi-axis motion speed v0, and the minimum movement accuracy m0 of the multi-axis motion, determine the second discrete step length l2 according to the maximum value,

[0019] where:

[0020] Optionally, the step of discretizing the digital surface into projection curves according to the first discrete step length and discretely analyzing the projection curves into a number of position points according to the second discrete step length includes:

[0021] Discretize the digital surface into a curve set according to the first discrete step length, where the curve set includes multiple decomposition curves arranged in a predetermined direction, and the predetermined direction is along the X direction or the Y direction;

[0022] Project the decomposition curves in the curve set onto the corresponding coordinate system plane to obtain projection curves, and discretely analyze the projection curves into a number of position points according to the second discrete step length.

[0023] Optionally, in the step of obtaining the first position information of each position point in the product coordinate system and converting the first position information into the second position information in the motion platform coordinate system:

[0024] The first position information includes: the rectangular coordinate information of the position point in the X direction, Y direction, and Z direction, and the curvature angle analyzed by the curvature corresponding to the position point on the projection curve.

[0025] Optionally, the step of obtaining first position information of each position point in the product coordinate system and converting the first position information into second position information in the motion platform coordinate system includes:

[0026] The first position information of each position point is converted by using the conversion path relationship obtained in advance, so as to obtain the corresponding second position information;

[0027] The steps of obtaining the preset conversion path relationship include:

[0028] Select the product coordinate origin in the product coordinate system, and determine the coordinate position of the corresponding point of the product coordinate origin in the motion coordinate system;

[0029] The transformation path relationship is obtained according to the positional relationship between the corresponding point and the motion coordinate origin of the motion coordinate system.

[0030] Optionally, the step of performing path planning for multi-axis linkage motion control according to the second position information includes:

[0031] Based on the condition that the laser processing and the multi-axis motion pulse are triggered in time, the laser spot is controlled to translate in the X direction or the Y direction, or / and, based on the condition that the processing does not exceed the quality standard threshold, the laser spot is controlled to translate in the Z direction;

[0032] or / and,

[0033] The irradiation angle of the laser spot is controlled according to the curvature angle of the position point, so that the laser light emission direction is perpendicular to the tangent line of the position point on the projection curve.

[0034] Optionally, based on the conditions of laser processing and the synchronous triggering of the multi-axis motion pulse, in the step of controlling the laser spot to translate in the X direction or the Y direction:

[0035] The conditions for triggering the laser processing and multi-axis motion pulses are:

[0036] According to the pulse frequency f0 of laser processing, the multi-axis motion speed v0, and the first discrete step length l1, the synchronous trigger is performed, which satisfies:

[0037]

[0038] Where n is a positive integer;

[0039] Based on the condition that the processing does not exceed the quality standard threshold, in the step of controlling the translation of the laser spot in the Z direction:

[0040] Predict the quality judgment index after the movement of the laser spot. Based on the condition that the quality judgment index is less than or equal to the preset comprehensive influence value, obtain the maximum value of the focal length change. Among them, the quality judgment index is determined by performing positive and negative and numerical weighting on the quantified groove aspect ratio, the quantified standard deviation of the groove width, the roughness of the molten pool on the surface of the quantified groove, and the height of the raised molten pool bed on both sides of the quantified groove relative to the original reference plane.

[0041] When the maximum value of the focal length change is not greater than the Z-axis change value, control the laser focus to move along the Z direction.

[0042] Optionally, in the step of controlling the irradiation angle of the laser spot according to the curvature angle of the position point so that the laser output direction is perpendicular to the tangent of the position point on the projection curve:

[0043] Based on the difference in the curvature angles of the same position point obtained by discrete analysis along the X direction and the Y direction respectively, select the larger curvature angle as the adjusted curvature angle of the position point.

[0044] Control the irradiation angle of the laser spot according to the adjusted curvature angle of the position point so that the laser output direction is perpendicular to the tangent of the position point on the projection curve.

[0045] On the other hand, the present application also proposes a machine tool, wherein the machine tool includes: a laser processing device and a multi-axis linkage device;

[0046] The laser processing device is arranged on the multi-axis linkage device and performs translational or / and rotational motion through the drive of the multi-axis linkage device;

[0047] The laser processing device and the multi-axis linkage device are controlled by the above-described method for analyzing the curved surface contour of laser multi-axis linkage machining to process the product.

[0048] Beneficial effects: A method and a machine tool for analyzing the curved surface contour in laser multi-axis linkage machining according to the present application obtain a first discrete step length and a second discrete step length based on laser processing parameters and multi-axis motion parameters, so as to perform adaptive contour analysis on the digital curved surface of the processed product while ensuring control and machining accuracy. Since the first discrete step length and the second discrete step length obtained by comparing the maximum and minimum values of each characteristic parameter are used as the criteria for contour analysis, the influence of the analysis process on the accuracy of the curved surface contour is minimized. During the process of reducing the dimension and discretizing the digital curved surface by the first discrete step length and the second discrete step length, the curved surface information is converted into the first position information of a number of position points. After converting the first position information into the second position information in the coordinate system of the motion platform, it is input into the machine tool control system, and finally, the path planning of the machining platform is carried out based on this. In this way, the laser processing and multi-axis linkage are effectively combined to achieve safe and stable machining of complex curved surfaces, reduce the setting conflict of the two characteristic parameters, and provide a new idea for path analysis of complex curved surfaces during actual machining. Description of the Drawings

[0049] Figure 1 It is a flowchart of the main steps of a method for analyzing the curved surface contour in laser multi-axis linkage machining according to an embodiment of the present application;

[0050] Figure 2 It is a flowchart of the detailed steps of a method for analyzing the curved surface contour in laser multi-axis linkage machining according to an embodiment of the present application;

[0051] Figure 3 It is a flowchart of the detailed steps of step S400 of a method for analyzing the curved surface contour in laser multi-axis linkage machining according to an embodiment of the present application;

[0052] Figure 4 It is a schematic diagram of the digital curved surface of a method for analyzing the curved surface contour in laser multi-axis linkage machining according to an embodiment of the present application;

[0053] Figure 5 It is a curve distribution diagram of the curved surface discretization of a method for analyzing the curved surface contour in laser multi-axis linkage machining according to an embodiment of the present application (discretized in the x direction and the y direction);

[0054] Figure 6 It is an X4 contour line diagram under the discretization in the X direction of a method for analyzing the curved surface contour in laser multi-axis linkage machining according to an embodiment of the present application;

[0055] Figure 7 It is a distribution diagram of the discrete position points on the contour line of a method for analyzing the curved surface contour in laser multi-axis linkage machining according to an embodiment of the present application;

[0056] Figure 8This is a distribution map of discrete position points on a digital surface in the moving platform coordinate system of a surface profile analysis method for laser multi-axis linkage machining according to an embodiment of the present application. Detailed implementation manners

[0057] To make the objectives, technical solutions and advantages of the present application clearer and more definite, the following further describes the present application in detail with reference to the accompanying drawings and by way of examples. It should be understood that the specific examples described herein are only used to explain the present application and are not used to limit the present application.

[0058] Embodiment 1

[0059] This embodiment provides a surface profile analysis method for laser multi-axis linkage machining, which is mainly applied to a machine tool provided with a laser processing device and a multi-axis linkage device. The multi-axis linkage device can be a five-axis linkage (three translation axes and two rotation axes), a four-axis linkage (three translation axes and one rotation axis), or a six-axis linkage (three translation axes and three rotation axes), etc., and is used for surface machining. The laser processing device has laser processing parameters, and the multi-axis linkage device has multi-axis motion parameters. Through this surface profile analysis method, the laser processing device and the multi-axis linkage device can be compatibly controlled to realize the machining of complex surfaces. This embodiment is preferably applied to a laser processing device and a five-axis linkage device.

[0060] As Figure 1 shown, a surface profile analysis method for laser multi-axis linkage machining in this embodiment performs surface profile analysis on the digital surface of a product to be machined, obtains a path planning for multi-axis linkage motion control, and enables the laser processing device to perform machining on the path. As Figure 4 shown, the digital surface of the machined product obtains the surface profile topography through contour scanning or through an existing 3D model diagram.

[0061] As Figure 1 shown, the surface profile analysis method of this embodiment includes the following steps:

[0062] Step S100: Determine a first discrete step length and a second discrete step length based on the laser processing parameters and the multi-axis motion parameters.

[0063] The laser processing parameters mainly refer to the minimum spot radius r0 of laser processing and the pulse frequency f0 of laser processing; the multi-axis motion parameters mainly refer to the multi-axis motion speed v0 and the minimum moving accuracy m0 of multi-axis motion; in addition, other factors affecting the accuracy are also considered, and the maximum and minimum values are compared in combination with various parameters, and the first discrete step length and the second discrete step length are defined through the "minimum accuracy impact criterion". Taking the first discrete step length and the second discrete step length as the criteria for dimensionality reduction and discretization, since both laser processing parameters and multi-axis motion parameters are taken into account, the control and processing accuracy can be guaranteed during the contour analysis process, and at the same time, the setting conflict of the two characteristic parameters can be reduced.

[0064] The first discrete step length is used to discretize the digital surface into a projection curve, and the second discrete step length discretely analyzes the projection curve into several position points.

[0065] Such as Figure 2 As shown, if the digital surface is directly obtained through the existing 3D model diagram, step S100 of this embodiment specifically includes:

[0066] S110. Compare the maximum values according to the minimum spot radius r0 of laser processing and the minimum moving accuracy m0 of multi-axis motion. According to the maximum value comparison result, determine the first discrete step length l1,

[0067] where: l1≥max{r0,m0};

[0068] In the specific process, directly compare the maximum values of the minimum spot radius r0 of laser processing and the minimum moving accuracy m0 of multi-axis motion. Then determine the first discrete step length l1, and the value of the first discrete step length l1 is greater than both the minimum spot radius r0 of laser processing and the minimum moving accuracy m0 of multi-axis motion.

[0069] Such as Figure 2 As shown, if the digital surface is obtained through 3D scanning, step S100 in this embodiment specifically includes:

[0070] S120. Compare the maximum values according to the minimum spot radius r0 of laser processing, the minimum moving accuracy m0 of multi-axis motion, and the scanning recognition accuracy error δ0 of 3D scanning. According to the maximum value comparison result, determine the first discrete step length l1,

[0071] where: l1≥max{r0,m0,δ0};

[0072] In the specific process, a digital surface is obtained through 3D scanning, and the scanning recognition accuracy error δ0 needs to be considered. Therefore, the maximum values of the minimum spot radius r0 of laser processing, the minimum movement accuracy m0 of multi-axis movement, and the scanning recognition accuracy error δ0 of 3D scanning are compared, and then the first discrete step length l1 is determined. The value of the first discrete step length l1 is greater than the minimum spot radius r0 of laser processing, the minimum movement accuracy m0 of multi-axis movement, and the scanning recognition accuracy error δ0.

[0073] As Figure 1 , Figure 2 shown, on the basis of the above steps, step S100 specifically further includes:

[0074] Step S130: According to the pulse frequency f0 of laser processing, the multi-axis movement speed v0, and the minimum movement accuracy m0 of multi-axis movement, determine the second discrete step length l2 according to the maximum value.

[0075] Where:

[0076] In the specific process, since the laser is a pulsed laser and there is a time interval for each light emission, when performing the discrete processing of reducing the two-dimensional contour line to one-dimensional, the step length of the second discretization should meet the above control conditions.

[0077] Step S200: Obtain the digital surface of the product to be processed, discretize the digital surface into a projection curve according to the first discrete step length, and discretely analyze the projection curve into several position points according to the second discrete step length.

[0078] Combined with the maximum value comparison of the above various characteristic parameters, each calculation parameter of the contour analysis model is limited by the "minimum accuracy impact criterion". Then, combined with the multi-axis movement mode, the dimensionality reduction and discretization of the spatial surface are performed to realize the conversion of the digital surface information of the product to be processed into the three-coordinate information of several position points and the corresponding curvature angle information.

[0079] The specific steps of step S200 in this embodiment include:

[0080] Step S210: Discretize the digital surface into a curve set according to the first discrete step length, where the curve set includes multiple decomposition curves arranged in a predetermined direction, and the predetermined direction is along the X direction or the Y direction.

[0081] In the specific process, for example, if the maximum value of the above parameters is 1, then the first discrete step length l1 = 1, and the digital surface is discretized into several decomposition curves according to the X direction or the Y direction. For example, Figure 6 the decomposition curves shown. The first discrete step length l1 is spaced between several decomposition curves to form a curve set. As Figure 5 shown, it can be discretized into a curve set {X1, X2, X3LX along the X direction24}, there is a set of curves {Y1, Y2, Y3, …, Y} along the Y direction 24}.

[0082] Step S220: Project the decomposed curves in the curve set onto the corresponding coordinate system plane to obtain projection curves, and discretely analyze the projection curves into a number of position points according to the second discrete step size.

[0083] Taking the set of curves {X1, X2, X3, …, X} obtained by contour discretization along the X direction as an example, select a single decomposed curve X4 for illustration. After projecting the selected X4 onto the corresponding coordinate system plane (Y0Z plane), the corresponding projection curve is obtained, and the result is as 24 shown. The corresponding coordinate system plane here refers to the plane coordinate system perpendicular to the discrete direction. Figure 6 As shown. Here, the corresponding coordinate system plane refers to the plane coordinate system perpendicular to the discrete direction.

[0084] For example, if the maximum value of the above parameters is 1, then the second discrete step size l2 = 1. Moving one unit of the second discrete step size along the Y-axis direction will obtain a position point on the projection curve of X4. Thus, the projection curve of the decomposed curve X4 is discretely analyzed into a number of position points.

[0085] Similarly, if surface discretization is performed along the Y direction, since the first discrete step size l1 and the second discrete step size l2 have the same constraint on both the X and Y dimensions, the step sizes in the two dimensions will be the same, and the distribution of the discrete points in the two dimensions will also be the same. However, the curvature on different projection planes is different. As Figure 7 shown, for example, along the X direction, its projection plane is the coordinate system plane ZOY, and the curvature angle is θ x ; along the Y direction, its projection plane is the coordinate system plane ZOX, and the curvature angle is θ y . After discretization is completed in one direction of the X or Y direction, discretization can be performed on the other direction, mainly to obtain different curvature angles θ x 、θ y of the same position point.

[0086] As Figure 1 、 Figure 2 shown, Step S300: Obtain the first position information of each position point in the product coordinate system, and convert the first position information into the second position information in the moving platform coordinate system. The rectangular coordinate information of the X, Y, and Z directions of this position point, and the curvature angle analyzed from the corresponding curvature of this position point on the projection curve.

[0087] In the specific process, after continuous dimensionality reduction and discrete analysis through the above steps, the digital surface to be processed is disassembled into a number of concrete position points. Each position point can obtain (x i , yj , z k ), the (x i , y j , z k ) is rectangular coordinate information, and the corresponding curvature angle θ is resolved from the curvature of the position point on the projection curve obtained by the positive projection on the corresponding coordinate system plane in the one-dimensional contour line x or θ y (as Figure 7 shown). It should be particularly noted that the above analysis process is based on the product coordinate system where the product is located, rather than the motion platform coordinate system of the multi-axis motion control system. Therefore, before performing motion control, it is necessary to complete the coordinate system conversion to convert the first position information of each position point in the product coordinate system into the second position information in the motion platform coordinate system.

[0088] When performing the coordinate system conversion, the conversion model is set to optimize the conversion process. Specifically: The position numerical results of the product coordinate system and the motion platform coordinate system are both defined according to the same absolute reference scale. The numerical changes of the product coordinate system and the motion platform coordinate system adopt the same change mode.

[0089] Therefore, step S300 of this embodiment specifically includes the following steps:

[0090] Step S310, pre-obtain the preset conversion path relationship.

[0091] The obtaining step of the preset conversion path relationship includes: Select the product coordinate origin in the product coordinate system, and determine the coordinate position of the corresponding point of the product coordinate origin in the motion coordinate system. According to the position relationship between the corresponding point and the motion coordinate origin of the motion coordinate system, obtain the conversion path relationship.

[0092] In the specific process: Find the origin position of the product coordinate system (product coordinate origin), and record the coordinate position of the corresponding point of this origin in the motion platform coordinate system. For example, the coordinate position of the corresponding point is (x0, y0, z0).

[0093] Using the translation idea, translate this corresponding point to the coordinate origin (motion coordinate origin) in the motion platform coordinate system. It should be noted that since the product is finally placed on the marking platform, at this time, in order to simplify the conversion process, it can be considered that there is no angular deflection between the three coordinate axes of the two coordinate systems, so the conversion method is limited to translation.

[0094] During the translation process, record the path information of the translation. Specifically: translate i units in the X direction → translate j units in the Y direction → translate k units in the Z direction. Thus, the position information of this position point in the moving platform coordinate system is obtained as (x0 ± i, y0 ± j, z0 ± k). Therefore, the conversion path relationship of (x ± i, y ± j, z ± k) is obtained, where x, y, and z are the coordinates of the position points in the product coordinate system.

[0095] Step S320: Convert the first position information of each position point through the pre-acquired conversion path relationship to obtain the corresponding second position information.

[0096] After converting the coordinates (x, y, z) of each position point in the product coordinate system, the coordinate values in the moving platform coordinate system are obtained as (x ± i, y ± j, z ± k).

[0097] Step S400: Perform path planning for multi-axis linkage motion control based on the second position information.

[0098] In the specific process, first, before setting the multi-axis linkage motion control mode, determine the reference standard for relative motion. In this embodiment, the laser focus of the laser processing device is fixed and the processed product is moved as the motion reference standard. Therefore, the main way of laser processing is that the laser spot is fixed, and the marking platform drives the processed product to move. Before laser processing, it is necessary to adjust the height of the laser focus. After focusing, record the specific value of the focus height (this value is measured in the moving platform coordinate system).

[0099] The multi-axis linkage process is split into a translational mode and a rotational mode. When performing linkage, first perform translation and then rotation. The specific analysis is as follows:

[0100] Such as Figure 2 、 Figure 3 As shown, if in the translational mode: Step S400 of this embodiment specifically includes:

[0101] Step S410: Based on the condition of matching trigger of laser processing and multi-axis motion pulses, control the laser spot to translate in the X direction or Y direction, or / and, based on the condition that the processing does not exceed the quality standard threshold, control the laser focus to translate in the Z direction.

[0102] In the condition of matching trigger of laser processing and multi-axis motion pulses, Step S410 specifically includes:

[0103] Step S401: Perform matching trigger according to the pulse frequency f0 of laser processing, the multi-axis motion speed v0, and the first discrete step length l1, where (first discrete step length / multi-axis motion speed) = (n / pulse frequency), that is:

[0104]

[0105] where n is a positive integer.

[0106] Among the conditions of processing not exceeding the quality standard threshold, step S410 specifically includes:

[0107] Step S411: Perform positive / negative and numerical weighting on the quantified groove depth-width ratio, the quantified standard deviation of groove width, the roughness of the molten pool on the groove surface, and the height of the raised molten pool bed on both sides of the groove relative to the original reference plane to determine the judgment standard of the quality judgment index; through this step, the standard of the quality judgment index can be determined.

[0108] Step S412: Predict the quality judgment index after the laser spot moves. Based on the condition that the quality judgment index is less than or equal to the preset comprehensive influence value, obtain the maximum value of the focal length change.

[0109] Step S413: When the maximum value of the focal length change is not greater than the Z-axis change value, control the laser focus to move along the Z direction.

[0110] In the specific process: Since the Z-axis movement involves the change of the focal point height, first, through experiments, determine the quality judgment index of the microstructure morphology quality processed by this specification and model of laser with respect to the change of the focal point height. The quality judgment index is defined as follows:

[0111] First, determine the judgment standard: Ensure that other processing parameters remain unchanged except for the change of the focal point height. Set the groove depth-width ratio α, the standard deviation of groove width σ, and the roughness of the molten pool on the groove surface The height λ of the raised molten pool bed on both sides of the groove relative to the original reference plane is the quality influencing factor.

[0112] According to the usage scenario of the product after laser processing, quantify a quality judgment index B for product use. Denote the product use quality corresponding to the initial unadjusted focal point height as B0. When the focal point height η changes, it causes changes in the quantified groove depth-width ratio α, the standard deviation of groove width σ, and the roughness of the molten pool on the groove surface The height λ of the raised molten pool bed on both sides of the groove relative to the original reference plane. Thus, it has an impact on the quality judgment index B. Therefore

[0113] When the change in the focal point height is Δη = η1 - η0, the change process of the corresponding quality judgment index B is:

[0114]

[0115] Therefore, after the change in the focal point height, it will affect the groove depth-width ratio α, the standard deviation of groove width σ, and the roughness of the molten pool on the groove surface The height λ of the raised molten pool bed on both sides of the groove relative to the original reference plane affects the final quality. When the focal length changes by Δη, the four factors also change as {Δα, Δσ, Δξ, Δλ} (these indicators have been quantified through experiments in advance). According to the experimental exploration, the degree of influence of the four factors on the quality can be obtained, and based on this, the corresponding weights {n0, n1, n2, n3} can be assigned (the weights are positive or negative according to the influence correlation). Thus, an influence feedback index τ is set. τ is a preset comprehensive influence value, which is obtained through experimental summary. When the quality judgment index B is less than or equal to τ, the quality after the focal length change is consistent with the comprehensive quality before the change. Finally, the maximum value Δη of the focal length change can be inversed according to the τ value. max 。

[0116] As Figure 8 shown, when applied to multi-axis translational control, for example, when moving from the current position point to the next position point, i.e., A0→A1, the corresponding Z-axis change value is z1 - z0 = Δz, and the following logical judgment exists for the translational control of the Z-axis:

[0117] Compare the Z-axis change value Δz with Δη max numerically. If Δz ≤ Δη max , then the Z-axis receives the A1 position signal and controls the laser spot to move from A0 to the A1 position; if Δz > Δη max , then although the Z-axis receives the A1 position signal, the Z-axis does not move.

[0118] If in the rotation mode:

[0119] As Figure 2 、 Figure 3 shown, step S400 of this embodiment specifically further includes:

[0120] Step S420: Control the irradiation angle of the laser spot according to the curvature angle of the position point so that the laser output direction is perpendicular to the tangent of the position point on the projection curve.

[0121] In the specific process, step S420 specifically includes:

[0122] Step S421: Based on the difference in the curvature angles of the same position point obtained by discrete analysis along the X direction and the Y direction respectively, select the larger curvature angle as the adjusted curvature angle of this position point.

[0123] Step S422: Control the irradiation angle of the laser spot according to the adjusted curvature angle of this position point so that the laser output direction is perpendicular to the tangent of the position point on the projection curve.

[0124] In the specific process: When performing one-dimensional contour analysis, the curvature angles of the same position point obtained by analyzing along the X-axis and Y-axis will be different. That is, along the X-axis, its projection plane is the coordinate plane ZOY, and the curvature angle is θ x ; along the Y-axis, its projection plane is the coordinate plane ZOX, and the curvature angle is θ y . Combining with the light-emitting mode of the laser, in order to ensure the light-emitting quality, it is generally necessary to ensure that the processing surface is perpendicular to the laser light-emitting direction. For this reason, rotation needs to be introduced during laser processing to correct the processing surface to be as perpendicular as possible to the laser light-emitting direction. The angle correction amount is generally the curvature angle value of this point in the moving coordinate system (the coordinate system determined by the moving platform). The correction angle also follows the following criterion:

[0125] The discrete position point distribution obtained by performing surface analysis and division along the X-axis. The curvature angle matrix D1 corresponding to each position point is:

[0126]

[0127] The discrete position point distribution obtained by performing surface analysis and division along the Y-axis. The curvature angle matrix D2 corresponding to each position point is:

[0128]

[0129] Introduce a selection model to optimize the two matrices. The specific process is as follows:

[0130]

[0131] Compare the curvature angles obtained for the same position point in two different discrete directions (i.e., the X-direction and Y-direction), and select the larger curvature angle as the adjusted curvature angle for this position point. Combine the adjusted curvature angles into a new curvature angle matrix D0. Finally, assign the values of D0 to each discrete point and use them for subsequent angle correction. For a point on the surface, it has different curvatures in different directions. Based on the actual motion control conditions, it is impossible to use universal rotation to consider the curvature values in all directions, which will bring a great burden to subsequent operations and cannot ensure stable and reasonable accuracy. For this reason, the larger curvature angle value is selected based on the basic coordinate axis directions in the moving coordinate system. Similarly, based on the maximum change in focal length Δη max , and through detection, it is found that there is a certain compatibility in the change of focal length. And the curvature angle ultimately affects the height of the focus. For this reason, there is also a certain compatibility in angle correction according to the curvature angle, which can provide a certain tolerance range for rotation adjustment.

[0132] If in the linkage mode:

[0133] The linkage mode can be decomposed into a translational mode + a rotational mode. And the control priority of the translational mode is higher than that of the rotational mode. In the translational mode, the control priority of the Z-axis direction is higher than that of the X / Y-axis directions. In order to ensure the machining quality as much as possible, it is necessary to control the moving speed of the translational mode and the angular velocity of the rotational mode to match the first incremental step length. If it is impossible to achieve speed matching due to the particularity of some surface contours, the stability of the translational mode must be given priority. There can be a control process where the translation is completed first and then waits for the rotation to complete.

[0134] Embodiment 2

[0135] This embodiment provides a machine tool, including: a laser processing device and a multi-axis linkage device. The laser processing device is arranged on the multi-axis linkage device and performs translational or / and rotational motion through the drive of the multi-axis linkage device. The laser processing device and the multi-axis linkage device are controlled by the surface contour analysis method of laser multi-axis linkage processing as described above to process products. In this embodiment, the multi-axis linkage device adopts a five-axis linkage device.

[0136] In summary, the present invention is mainly used for laser surface processing on complex surfaces. At the same time, it will combine the multi-axis linkage control of the processing platform to liberate the design freedom of complex surface processing, reduce the limitations of the laser processing method in surface shape, and provide new ideas for the organic combination of multi-axis linkage control and laser processing method.

[0137] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the present application in each embodiment.

Claims

1. A surface profile analysis method for laser multi-axis linkage processing, characterized in that: The surface profile analysis method comprises the steps of: Determining a first discrete step length and a second discrete step length based on the laser processing parameters and the multi-axis motion parameters; Acquire a digitized surface of a product to be processed, discretize the digitized surface into a projection curve according to a first discrete step length, and discretize and resolve the projection curve into a plurality of position points according to a second discrete step length; Acquire first position information of each position point in the product coordinate system, and convert the first position information into second position information in the motion platform coordinate system; Performing path planning for multi-axis linkage motion control according to the second position information; The step of determining the first discrete step length and the second discrete step length based on the laser processing parameters and the multi-axis motion parameters comprises: According to the minimum spot radius r0 of laser processing and the minimum moving accuracy m0 of multi-axis motion, the maximum value comparison is performed, and the first discrete step length l1 is determined according to the maximum value comparison result. Where: l1≥max{r0,m0}; or, According to the minimum spot radius r0 of laser processing, the minimum moving accuracy m0 of multi-axis motion and the scanning recognition accuracy error δ0 of 3D scanning, the maximum value comparison is performed, and the first discrete step length l1 is determined according to the maximum value comparison result. Where: l1≥max{r0,m0,δ0}; The step of determining the first discrete step length and the second discrete step length based on the laser processing parameters and the multi-axis motion parameters also includes: According to the pulse frequency f0 of laser processing, the multi-axis motion speed v0 and the minimum moving accuracy m0 of multi-axis motion, the second discrete step length l2 is determined according to the maximum value. in:

2. The surface contour analysis method of laser multi-axis linkage machining according to claim 1, characterized in that: The step of discretizing the digitized surface into a projection curve according to the first discrete step length, and discretizing and resolving the projection curve into a plurality of position points according to the second discrete step length comprises: Discretizing the digitized surface into a curve set according to a first discrete step length, wherein the curve set includes a plurality of decomposed curves arranged in a predetermined direction, wherein the predetermined direction is along the X direction or along the Y direction; The decomposed curves in the curve set are forward projected on the corresponding coordinate system plane to obtain a projection curve, and the projection curve is discretized into a plurality of position points according to the second discrete step length.

3. The surface contour analysis method of laser multi-axis linkage machining according to claim 2, characterized in that: In the step of obtaining the first position information of each position point in the product coordinate system and converting the first position information into the second position information in the motion platform coordinate system: The first position information includes: rectangular coordinate information of the position point in the X direction, the Y direction and the Z direction, and the curvature angle resolved by the curvature corresponding to the position point on the projection curve.

4. The surface contour analysis method of laser multi-axis linkage machining according to claim 3 is characterized in that: The step of acquiring the first position information of each position point in the product coordinate system and converting the first position information into the second position information in the motion platform coordinate system comprises: The first position information of each position point is converted by using the conversion path relationship obtained in advance, so as to obtain the corresponding second position information; The steps of obtaining the preset conversion path relationship include: Selecting a product coordinate origin in the product coordinate system, and determining a coordinate position of a corresponding point of the product coordinate origin in the motion coordinate system; The conversion path relationship is acquired according to the positional relationship between the corresponding point and the motion coordinate origin of the motion coordinate system.

5. The surface contour analysis method of laser multi-axis machining according to claim 3, characterized in that: The step of performing path planning for multi-axis linkage motion control according to the second position information comprises: Based on the condition that the laser processing and the multi-axis motion pulse are triggered in time, the laser spot is controlled to translate in the X direction or the Y direction, or / and, based on the condition that the processing does not exceed the quality standard threshold, the laser spot is controlled to translate in the Z direction; or / and, The irradiation angle of the laser spot is controlled according to the curvature angle of the position point, so that the laser light emission direction is perpendicular to the tangent line of the position point on the projection curve.

6. The surface contour analysis method of laser multi-axis machining according to claim 5, characterized in that: In the step of controlling the laser spot to translate in the X direction or the Y direction based on the conditions of the laser processing and the synchronous triggering of the multi-axis motion pulses: The conditions for triggering the laser processing and multi-axis motion pulses in synchronization are: According to the pulse frequency f0 of laser processing, the multi-axis motion speed v0, and the first discrete step length l1, the synchronous trigger is performed, which satisfies: Where n is a positive integer; In the step of controlling the laser spot to translate in the Z direction based on the condition that the processing does not exceed the quality standard threshold: Pre-judge the quality judgment index after the laser spot moves, and obtain the maximum value of the focal length change under the condition that the quality judgment index is less than or equal to the preset comprehensive influence value; wherein the quality judgment index is determined by weighting the quantified groove aspect ratio, the quantified groove width standard deviation, the quantified groove surface molten pool roughness, and the quantified height of the molten pool bed on both sides of the groove relative to the original reference plane by positive and negative and numerical weighting; When the maximum focal length change is not greater than the Z-axis change value, the laser focus is controlled to move along the Z direction.

7. The surface contour analysis method of laser multi-axis machining according to claim 5, characterized in that: In the step of controlling the irradiation angle of the laser spot according to the curvature angle of the position point so that the laser light emission direction is perpendicular to the tangent line of the position point on the projection curve: Based on the difference in curvature angles of the same position point obtained by discrete analysis along the X direction and along the Y direction, a larger curvature angle is selected as the adjusted curvature angle of the position point; The irradiation angle of the laser spot is controlled according to the adjusted curvature angle of the position point, so that the laser light emitting direction is perpendicular to the tangent line of the position point on the projection curve.

8. A machine tool, characterized in that: include: Laser processing device and multi-axis linkage device; The laser processing device is arranged on the multi-axis linkage device, and is driven by the multi-axis linkage device to perform translational and / or rotational motion; The laser processing device and the multi-axis linkage device are controlled by the surface contour analysis method of laser multi-axis linkage processing as described in any one of claims 1 to 7 to process the product.

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