A metal part cutting method and system based on path planning

Abstract

The application relates to the technical field of numerical control machining, and discloses a metal part cutting machining method and system based on path planning, which comprises the following steps: fusing and calculating the cutting removal amount requirement and the surface geometric characteristics of a metal part, laying nodes on the metal part according to a density field obtained through calculation; constructing a topological connection scheme, analyzing the thermal cumulative effect of the topological connection scheme, selecting a target topological connection scheme, and outputting an initial tool path trajectory; planning the initial tool path trajectory by taking a residual stress direction field as a conditional constraint, adjusting the direction of the initial tool path trajectory according to a feeding direction; judging the feasibility of the tool path trajectory after direction optimization, correcting the tool path trajectory according to a judgment result, and outputting a final planning path. The application can realize the collaborative optimization of machining efficiency and machining precision, and effectively suppresses the machining deformation caused by cutting thermal accumulation and residual stress.

Description

Technical Field

[0001] This invention relates to the field of CNC machining technology, and in particular to a method and system for cutting metal parts based on path planning. Background Technology

[0002] Existing toolpath planning methods typically use the geometric shortest path or machining time as the sole optimization objective, employing strategies such as isoparametric methods and isoresidual height methods to generate trajectories. However, they generally neglect the thermo-mechanical coupling physical effects during the cutting process. On the one hand, cutting heat continuously accumulates along the path. When the path topology is unreasonable, heat conduction and superposition between adjacent path segments can easily cause local high temperatures, leading to tool thermal deformation and workpiece thermal expansion, resulting in machining dimensional deviations and surface quality deterioration. On the other hand, residual stress distribution has significant directionality, and different feed directions disturb the residual stress field in different ways. Existing path planning lacks an active feed direction control mechanism guided by the residual stress direction field, making it difficult to fundamentally suppress machining deformation caused by residual stress release.

[0003] Furthermore, node placement often employs uniform or empirical strategies, failing to differentiate density settings based on the distribution of material removed and differences in surface curvature. After path generation, there is a lack of dual feasibility assessment and closed-loop correction processes based on thermal accumulation effects and material removal requirements, making it difficult to guarantee the machining accuracy and surface integrity of complex metal parts. Therefore, there is an urgent need to develop a path planning method that integrates intelligent node placement based on material removal and geometric features, optimizes topology connections using thermal accumulation effects and path length as joint evaluation indicators, actively controls the feed direction using the residual stress direction field as a constraint, and possesses feasibility assessment and closed-loop correction capabilities. This would address the problems of disconnect between path planning and physical effects, and the lack of coordinated control over thermal accumulation and residual stress in existing technologies, thereby improving the machining consistency of metal parts. Summary of the Invention

[0004] This invention provides a method and system for machining metal parts based on path planning, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides a metal parts cutting method based on path planning, comprising:

[0006] S01: The cutting removal amount requirement of the metal parts is calculated by integrating the surface geometric features, and the nodes of the metal parts are arranged according to the calculated density field.

[0007] S02: Based on the initial path nodes of the metal parts, construct a topology connection scheme, and analyze the thermal accumulation effect of the topology connection scheme according to the process parameters and material properties of the metal parts. Using path length and thermal accumulation effect as joint evaluation indicators, select the target topology connection scheme and output the initial tool path trajectory.

[0008] S03: Using the residual stress direction field of the metal component as a constraint, the initial tool path trajectory is planned to obtain the feed direction, and the initial tool path trajectory is adjusted according to the feed direction;

[0009] S04: Determine the feasibility of the optimized toolpath trajectory and correct the toolpath trajectory according to the determination result until the preset consistency condition is met, and output the final planned path.

[0010] To address the above problems, the present invention also provides a metal parts cutting system based on path planning, the system comprising:

[0011] The node layout module is used to perform a fusion calculation of the cutting removal requirements and surface geometric features of the metal parts, and to lay out the nodes of the metal parts according to the calculated density field.

[0012] The path generation module is used to construct a topology connection scheme based on the path nodes of the metal parts, and to perform thermal accumulation effect analysis on the topology connection scheme according to the process parameters and material properties of the metal parts. The target topology connection scheme is selected with path length and thermal accumulation effect as joint evaluation index, and the initial tool path trajectory is output.

[0013] The path adjustment module is used to plan the initial tool path trajectory based on the residual stress direction field of the metal parts as a condition constraint, obtain the feed direction, and adjust the direction of the initial tool path trajectory according to the feed direction.

[0014] The feasibility determination module is used to determine the feasibility of the optimized toolpath trajectory and correct the toolpath trajectory according to the determination result until the preset consistency conditions are met, and output the final planned path.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. This invention achieves a dual improvement in processing efficiency and thermal control by intelligent node layout that integrates cutting removal requirements with surface geometric features, and topology connection optimization using path length and thermal accumulation effect as joint evaluation indicators. In the node layout stage, this invention overcomes the limitations of traditional uniform or empirical node layout strategies by mapping the cutting removal distribution to surface curvature features. Path nodes are densely deployed in areas with high removal volume or drastic curvature changes, and sparsely deployed in flat areas. This ensures processing accuracy for complex geometric features while effectively reducing unnecessary calculations and idle tool paths. In the topology connection optimization stage, this invention introduces a quantitative analytical mechanism for thermal accumulation effect. By establishing an attenuation model for heat propagation between path nodes, a comprehensive cost assessment is performed using path length and thermal accumulation effect as joint evaluation indicators to select the optimal topology connection scheme. Existing research has shown that thermal deformation of long workpieces caused by cutting heat accumulation significantly affects processing accuracy, while path optimization can significantly reduce the overall temperature rise of the workpiece and the amount of workpiece deformation. This invention, by quantitatively evaluating and actively controlling the heat accumulation effect during the path planning stage, can fundamentally suppress tool thermal deformation and workpiece thermal expansion caused by local overheating, effectively avoid dimensional deviations and surface quality deterioration, and significantly improve the machining accuracy and surface integrity of metal parts.

[0017] 2. This invention achieves coordinated control of physical effects in the machining process and engineering-based closed-loop optimization of the toolpath through an active feed direction control mechanism constrained by the residual stress direction field, and a dual feasibility assessment and closed-loop correction process based on thermal accumulation effect and material removal requirements. Regarding feed direction control, this invention overcomes the limitations of existing technologies where research on the correlation between residual stress and toolpath is limited to qualitative analysis and post-compensation. It collects residual stress using stress detection equipment and constructs a continuous residual stress direction field, using the main residual stress direction as a constraint benchmark to determine the feed direction of each path segment. Since different feed directions fundamentally differ in their disturbance mechanisms to the residual stress field, this invention actively controls the feed direction to match the cutting force direction with the main residual stress direction, effectively suppressing machining deformation caused by residual stress release. In terms of feasibility assessment and closed-loop correction, this invention updates the thermal accumulation effect of the toolpath trajectory after direction optimization, and uses the updated thermal accumulation effect and material removal requirements as dual benchmarks for feasibility assessment. Path segments that do not meet the consistency conditions are marked and topology corrections are implemented. Through an iterative closed-loop process of "planning-judgment-correction", the final output tool path trajectory is ensured to be not only theoretically optimal, but also physically feasible and an engineering path that meets consistency requirements. This significantly improves the machining deformation control capability and dimensional consistency level of complex metal parts such as thin-walled parts and frame beam structural parts. Attached Figure Description

[0018] Figure 1This is a schematic flowchart of a metal parts cutting method based on path planning, provided in an embodiment of the present invention.

[0019] Figure 2 This is a functional block diagram of a metal parts cutting system based on path planning, provided as an embodiment of the present invention.

[0020] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0022] This application provides a method for machining metal parts based on path planning. The execution entity of this method includes, but is not limited to, at least one of the following electronic devices that can be configured to execute the method provided in this application: a server, a terminal, etc. In other words, the method for machining metal parts based on path planning can be executed by software or hardware installed on a terminal device or a server device. The server includes, but is not limited to, a single server, a server cluster, a cloud server, or a cloud server cluster. The server can be an independent server or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, content delivery networks (CDNs), and big data and artificial intelligence platforms.

[0023] Reference Figure 1 The diagram shown is a schematic flowchart of a metal parts cutting method based on path planning according to an embodiment of the present invention. In this embodiment, the metal parts cutting method based on path planning includes:

[0024] S01: The cutting removal amount requirement of the metal parts is calculated by integrating the surface geometric features, and the nodes of the metal parts are arranged according to the calculated density field.

[0025] In this embodiment of the invention, when performing surface discretization processing on the three-dimensional model of the metal parts, the three-dimensional model is imported into the geometric processing environment, and the surface boundary of the three-dimensional model is divided into triangular meshes. By setting the side length of the triangular mesh to a fixed value, the surface of the three-dimensional model is decomposed into a set of several planar triangular facets. These planar triangular facets together constitute the surface mesh model of the metal parts. The surface mesh model completely preserves the surface topology and spatial contour information of the original three-dimensional model.

[0026] When performing curvature analysis on the surface mesh model, the normal vector of each triangular facet in the surface mesh model is extracted sequentially, and the angle between the normal vectors of adjacent triangular facets is calculated. Then, based on the distance between the angle and the center point of the adjacent facet, the principal curvature radius of the region is calculated. The reciprocal of the principal curvature radius is taken as the curvature value of the region. After traversing all the triangular facets of the surface mesh model, the surface geometric features reflecting the degree of surface undulation of the metal parts are obtained. The surface geometric features record the geometric complexity at each mesh location in the form of spatial distribution.

[0027] When performing spatial registration between the 3D model and the blank model of the metal part, the boundary extreme points of the 3D model in the three principal axes of the spatial rectangular coordinate system are extracted. At the same time, the boundary extreme points of the blank model in the same coordinate system are also extracted. Through translation transformation, the center point of the 3D model coincides with the center point of the blank model. Then, using the boundary extreme points of the 3D model as the reference, the blank model is rotated and adjusted around the three principal axes to make the boundary extreme points of the blank model correspond one-to-one with the boundary extreme points of the 3D model in space. Finally, the spatial registration between the 3D model and the blank model is completed, so that the two models are in the same spatial pose.

[0028] When performing Boolean difference operation on the registered model, the registered 3D model is removed from the blank model. That is, the part of the blank model located outside the surface of the 3D model is retained, and the part of the blank model located inside the surface of the 3D model is removed. The spatial volume retained after Boolean difference operation is the cutting removal amount requirement. This cutting removal amount requirement is recorded in the form of a voxelized mesh, showing the thickness and volume of the material to be removed at each spatial location.

[0029] When calculating the cutting removal requirements of metal parts in conjunction with surface geometric features, the curvature value of the surface geometric features and the material removal thickness in the cutting removal requirements are weighted and superimposed at the same spatial location. That is, the surface geometric features are given higher weight in areas with larger curvature values, and the cutting removal requirements are given higher weight in areas with larger cutting removal requirements. The point intensity distribution at each location on the surface of the metal parts is obtained through this weighted superposition calculation. This point intensity distribution represents the intensity of the demand for path nodes at each spatial location in numerical form.

[0030] When constructing a density field based on the intensity distribution of the points, the discrete values ​​in the intensity distribution are extended to the entire processing surface through radial basis function interpolation. The intensity value is diffused outward from each discrete point to the surrounding area according to the distance. The closer the location is to the center point, the higher the intensity value is obtained, and the farther the location is, the lower the intensity value is obtained. The diffusion effect of all discrete points is superimposed in space to form a continuous density field covering the entire processing surface. The value of this density field at each spatial location represents the relative density of the path nodes that need to be placed at that location.

[0031] When determining the threshold of the processed surface of metal parts based on the density field, the values ​​of all spatial locations in the density field are first sorted from largest to smallest. The value at a specific percentile after sorting is used as the preset threshold. Then, the value of each spatial location in the density field is compared with the preset threshold one by one. All spatial locations with density field values ​​higher than the preset threshold are marked as high-density areas, and all spatial locations with density field values ​​lower than the preset threshold are marked as low-density areas. The purpose of this threshold determination is to divide the processed surface into two types of areas with different node density.

[0032] When densifying the high-density layout area, sampling is performed at equal intervals within the boundary of the high-density layout area according to a preset grid step size. The value of the grid step size is obtained by dividing the minimum side length of the high-density layout area by a fixed integer, ensuring that the spatial interval of sampling in the high-density layout area is smaller than the sampling interval of the low-density layout area. When sparsely laying out the low-density layout area, sampling is performed within the boundary of the low-density layout area at a spatial interval greater than the grid step size of the high-density layout area, so that the spatial interval of sampling in the low-density layout area is an integer multiple of the sampling interval of the high-density layout area. After densification and sparse laying out, all sampling points together constitute the initial path nodes of the metal parts, and each initial path node has its precise spatial coordinates on the machined surface.

[0033] The beneficial effect is that by integrating the cutting removal requirements with the surface geometric features to construct a density field, and dividing the processed surface into high-density and low-density areas based on the density field threshold, a differentiated node distribution is achieved, with denser placement in high-curvature, high-removal-volume areas and sparse placement in flat, low-removal-volume areas. This ensures that the path node density is precisely matched with the physical requirements of the processing area, guaranteeing the trajectory fitting accuracy and control capability for complex geometric features and heavily cutting areas, while avoiding node redundancy and computational resource waste caused by uniform placement. From the source of path planning, it provides a spatially reasonable and information-rich initial node set for subsequent topology connections and path optimization.

[0034] In another feasible implementation, the surface discretization of the three-dimensional model of the metal parts is completed by quadrilateral mesh generation.

[0035] Specifically, after importing the 3D model into the geometry processing environment, the node positions of quadrilateral meshes are set on the surface boundary of the 3D model according to fixed side lengths. Each node is connected to its surrounding adjacent nodes to form quadrilateral patches. The four vertices of the quadrilateral patches are coplanar and adjacent quadrilateral patches share common edges. This quadrilateral partitioning operation is performed sequentially on all regions of the 3D model surface, so that the surface of the 3D model is decomposed into a set of quadrilateral patches. The set of quadrilateral patches together constitutes the surface mesh model of the metal parts. The surface mesh model completely preserves the surface topology and spatial contour information of the original 3D model. This method requires fewer patches than triangular meshes when the processed surface has regular geometric features and the curvature changes gently. Under the same number of patches, quadrilateral meshes have higher approximation accuracy to the surface.

[0036] In another feasible implementation, curvature analysis of the surface mesh model is performed by fitting a quadratic surface to each mesh vertex in the surface mesh model.

[0037] Specifically, each grid vertex in the surface mesh model is taken as the target vertex. All grid vertices in several adjacent layers around the target vertex are selected to form a local neighborhood point cloud. The coordinates of all vertices in the local neighborhood point cloud are fitted with least squares to obtain the quadratic surface equation. The second-order partial derivatives of the quadratic surface equation along the two principal directions are solved. The principal radius of curvature at the target vertex is calculated based on the second-order partial derivatives. The reciprocal of the principal radius of curvature is taken as the curvature value at the target vertex. The above fitting operation is performed on all grid vertices in the surface mesh model in sequence to obtain the curvature value at each grid vertex. The curvature value is spatially interpolated to obtain a continuous curvature distribution. This continuous curvature distribution is taken as the surface geometric feature. The surface geometric feature records the geometric complexity at each spatial location in the form of a spatial distribution. This method can obtain more stable curvature estimates when the grid vertex distribution is uneven or the grid connection is irregular.

[0038] S02: Based on the initial path nodes of the metal parts, construct a topology connection scheme, and analyze the thermal accumulation effect of the topology connection scheme according to the process parameters and material properties of the metal parts. Using path length and thermal accumulation effect as joint evaluation indicators, select the target topology connection scheme and output the initial tool path trajectory.

[0039] In this embodiment of the invention, when constructing candidate topology connection schemes based on the neighborhood relationships of initial path nodes, the spatial straight-line distance between each initial path node and all other initial path nodes on the processing surface is calculated, with each initial path node as the center. Several nodes closest to the node are selected as the set of neighboring nodes of the node in order of distance from nearest to farthest. Under the premise of ensuring that each node is connected to at least one neighboring node, a variety of different connection order combinations are generated by changing the connection pairing order between each node and its neighboring nodes. Each connection order combination corresponds to a candidate topology connection scheme. Each candidate topology connection scheme completely covers all initial path nodes and defines the front and back connection order between each node.

[0040] When obtaining the spatial location of the path node in the candidate topology connection scheme and the cutting removal amount corresponding to the path node, the three-dimensional spatial coordinate value of each path node on the machining surface is directly read from the storage data of the initial path node. At the same time, the material removal thickness value at the spatial location of each path node is extracted from the voxelized mesh of the cutting removal amount requirement. The three-dimensional spatial coordinates of each path node are bound to the material removal thickness value at that location to form the complete attribute data of the path node.

[0041] When using process parameters and material removal amount as inputs to statistically analyze the instantaneous heat generation intensity of a path node, the cutting speed and feed rate of the tool are multiplied to obtain the cutting area swept by the tool per unit time. This cutting area is then multiplied by the material removal thickness at the path node to obtain the material removal volume per unit time. Finally, this material removal volume is multiplied by the specific energy coefficient of the metal material under cutting conditions. This specific energy coefficient is obtained by consulting the cutting performance manual of the metal material. The final product value is the instantaneous heat generation intensity at the path node, which characterizes the cutting heat generated by the tool at that node position per unit time.

[0042] When calculating the spatial distance between path nodes based on spatial location, for any two path nodes in the candidate topology connection scheme, extract their three-dimensional spatial coordinate values, calculate the difference between the two coordinate values ​​in the three spatial axes, square them respectively, add them together, and then take the square root of the sum to obtain the spatial straight-line distance between the two path nodes. After traversing all node pairs in the candidate topology connection scheme, obtain the spatial distance value between each pair of path nodes.

[0043] Using spatial distance as the attenuation basis for heat propagation, the path resistance coefficient is determined based on the thermal conductivity and thermal diffusion characteristic length in the material properties. The thermal conductivity value of the material is read from the material property database of the metal parts. This thermal conductivity value reflects the inherent rate of heat conduction by the material. At the same time, the thermal diffusion characteristic length of the material is read. This thermal diffusion characteristic length is obtained by dividing the thermal conductivity of the material by the product of the material's density and specific heat capacity and then taking the square root. The ratio of thermal conductivity to thermal diffusion characteristic length is used as the reference value of the path resistance coefficient. Then, this reference value is multiplied by the heat propagation resistance correction factor of the processed surface roughness. This correction factor is obtained by looking up the empirical relationship curve between surface roughness and heat reflectivity. Finally, the path resistance coefficient applicable to the current processing conditions is obtained. This path resistance coefficient reflects the degree of combined resistance of the material's own properties and surface conditions when heat propagates between path nodes.

[0044] When calculating the proportion of residual heat at a path node when it propagates to adjacent path nodes based on path resistance coefficient, spatial distance, and instantaneous heat generation intensity, and outputting the thermal conductivity coefficient, the process examines the propagation of heat from the initial path node to each subsequent path node in the candidate topology connection scheme, centered on the initial path node that generates heat. The instantaneous heat generation intensity at the initial node is multiplied by an exponential decay function with a base of the natural constant. The exponent of this function is determined by the path resistance coefficient, the spatial distance between the initial and target nodes, and the length of the heat diffusion characteristic. Additionally, the accumulated preceding temperature at the initial node and the surrounding temperature are also considered. The ratio of the ambient reference temperature and the ratio of the actual feed rate to the reference feed rate are used as adjustment factors. When the spatial distance is larger, the absolute value of the exponential part is larger, resulting in a smaller proportion of residual heat. When the path resistance coefficient is larger, the absolute value of the exponential part is larger, resulting in a smaller proportion of residual heat. When the thermal diffusion characteristic length is larger, the absolute value of the exponential part is smaller, resulting in a larger proportion of residual heat. After the above calculation, the proportion of residual heat when the heat from the starting node propagates to any subsequent node to the instantaneous heat generation intensity of the starting node is obtained. This proportion is defined as the thermal conductivity coefficient, which characterizes the degree of heat loss during the propagation process along the path.

[0045] When recursively accumulating heat node by node, starting from the initial path node, the first path node defined in the candidate topology connection scheme is taken as the starting node. The instantaneous heat generation intensity of the starting node is directly used as the heat accumulation amount of that node. For the subsequent second path node, the instantaneous heat generation intensity of the second node is added to the heat propagated from the starting node to the second node. This propagated heat is equal to the instantaneous heat generation intensity of the starting node multiplied by the thermal conductivity coefficient from the starting node to the second node, thus obtaining the heat accumulation amount of the second node. For each subsequent path node, the instantaneous heat generation intensity of that node is accumulated with the heat propagated from all preceding path nodes to that node. The propagated heat of each preceding node is equal to the instantaneous heat generation intensity of that preceding node multiplied by the thermal conductivity coefficient from the preceding node to the current node. After each recursion, the heat accumulation amounts of all calculated nodes are arithmetically calculated. The average value is used as the preceding accumulated temperature in the heat transfer calculation of subsequent nodes. This is because the preceding accumulated temperature reflects the overall heat level of the processed area. The higher the temperature, the lower the heat transfer efficiency received by subsequent nodes. Therefore, the ratio of the preceding accumulated temperature to the ambient reference temperature is introduced as a reverse adjustment factor in the calculation of the heat transfer coefficient from the preceding node to the current node. The ambient reference temperature is obtained by measuring the ambient temperature of the processing workshop, and the reference feed rate is obtained by consulting the recommended cutting parameter table provided by the tool supplier. The calculation is performed sequentially along the node order of the candidate topology connection scheme according to the above recursive rules until the last path node, and the heat accumulation of all path nodes is obtained. The heat accumulation effect of the candidate topology connection scheme is obtained by aggregating and organizing all the heat accumulation values. This heat accumulation effect is presented in the form of a sequence of final accumulated heat values ​​at each path node.

[0046] When calculating the path length of a candidate topology connection scheme, the spatial straight-line distance between each pair of adjacent path nodes is extracted sequentially along the node connection order defined in the candidate topology connection scheme. The spatial distance values ​​between all adjacent node pairs are summed to obtain the total path length of the candidate topology connection scheme.

[0047] When evaluating the comprehensive cost using the heat accumulation effect and path length corresponding to the candidate topology connection scheme as joint evaluation indicators, the average heat accumulation of all path nodes in the heat accumulation effect is calculated to obtain the average heat accumulation. The path length and the average heat accumulation are divided by the maximum path length and the maximum average heat accumulation among all candidate topology connection schemes, respectively, to obtain the normalized path length ratio and the normalized heat accumulation ratio. The normalized path length ratio and the normalized heat accumulation ratio are added together with equal weights to obtain the comprehensive cost of the candidate topology connection scheme. The smaller the comprehensive cost, the better the comprehensive performance of the scheme in terms of both path length and thermal control.

[0048] The candidate topology connection scheme with the lowest replacement value is selected as the target topology connection scheme. According to the path node connection order defined by the target topology connection scheme, the path nodes are connected sequentially from the first path node to the last path node. Adjacent path nodes are connected by straight line segments. All straight line segments are connected end to end to form a complete continuous spatial polyline trajectory. The continuous spatial polyline trajectory is output as the initial toolpath trajectory. The initial toolpath trajectory contains the spatial coordinates of all path nodes and their sequential connection order.

[0049] The beneficial effects are as follows: by constructing candidate topology connection schemes and analyzing the thermal accumulation effect of each scheme, a comprehensive cost assessment is conducted using path length and thermal accumulation effect as joint evaluation indicators, and the scheme with the lowest replacement value is selected as the target topology connection scheme. This overcomes the shortcomings of existing technologies that only focus on the shortest path as the sole optimization objective and ignore the thermal accumulation effect of cutting. At the same time, it makes up for the shortcomings of simply pursuing heat dissipation at the expense of machining efficiency. The target topology connection scheme achieves an optimal balance between path length and thermal control. It actively suppresses the excessive concentration and superposition of cutting heat at the path planning level, effectively reducing the risk of thermal deformation in the machining area and the tool thermal wear rate. Furthermore, by introducing the preceding accumulated temperature as a reverse adjustment factor for heat propagation, the analysis of the thermal accumulation effect is made closer to the hindering effect of the heat level of the machined area on subsequent heat conduction during the actual cutting process. This improves the accuracy and engineering applicability of thermal accumulation prediction and provides an initial tool path trajectory that takes into account both efficiency and thermal stability for subsequent path direction adjustment and feasibility determination.

[0050] In another feasible implementation, when performing heat accumulation recursion node by node starting from the initial path node, a simplified recursion method that only considers the immediate preceding node is used.

[0051] Specifically, taking the first path node defined in the candidate topology connection scheme as the starting node, the instantaneous heat generation intensity of the starting node is directly used as the heat accumulation of that node. For each subsequent path node, only the instantaneous heat generation intensity of that path node is added to the heat propagated from the previous path node to that path node. The heat propagated from the previous path node is equal to the instantaneous heat generation of the previous path node multiplied by the heat transfer coefficient from the previous path node to the current path node. The heat propagated from earlier preceding nodes is not accumulated. The above simplification rule is applied sequentially along the node order of the candidate topology connection scheme until the last path node, obtaining the simplified heat accumulation of all path nodes. The computational complexity of this method is linearly related to the number of path nodes. It has higher computational efficiency when the initial number of path nodes is large and a large number of candidate topology connection schemes need to be compared quickly, making it suitable for application scenarios with high response speed requirements for online real-time path planning.

[0052] In another feasible implementation, a non-equal weighting method is used to evaluate the comprehensive cost by taking the heat accumulation effect and path length corresponding to the candidate topology connection scheme as joint evaluation indicators.

[0053] Specifically, the path cost component is obtained by multiplying the normalized path length ratio by the path weight coefficient, and the thermal accumulation cost component is obtained by multiplying the normalized heat accumulation ratio by the thermal accumulation weight coefficient. The comprehensive cost of the candidate topology connection scheme is obtained by adding the path cost component and the thermal accumulation cost component. The sum of the path weight coefficient and the thermal accumulation weight coefficient is equal to one. When the workpiece is a thin-walled structure and the material has poor thermal conductivity, the thermal accumulation weight coefficient is greater than the path weight coefficient, so that the comprehensive cost focuses more on selecting the scheme with low thermal accumulation effect to avoid thermal deformation of thin-walled parts. When the workpiece is a thick-walled structure... When the structure and material have good thermal conductivity, the path weight coefficient is greater than the heat accumulation weight coefficient, so that the overall cost value focuses more on selecting the solution with shorter path length to improve processing efficiency. When the heat accumulation weight coefficient is 0.7 and the path weight coefficient is 0.3, the overall cost value is biased towards thermal control. When the heat accumulation weight coefficient is 0.3 and the path weight coefficient is 0.7, the overall cost value is biased towards efficiency priority. By adjusting the ratio of the weight coefficients, the overall cost assessment of different emphases on path length and heat accumulation effect can be realized, so that the method has flexible adaptability in different processing scenarios.

[0054] S03: Using the residual stress direction field of the metal component as a constraint, the initial tool path trajectory is planned to obtain the feed direction, and the initial tool path trajectory is adjusted according to the feed direction;

[0055] In this embodiment of the invention, when collecting residual stress of metal parts using a stress detection device, the probe of the X-ray stress detector is vertically aligned with the measurement point on the machined surface of the metal parts. The characteristic X-rays generated by the X-ray tube irradiate the crystal surface at the measurement point at a fixed incident angle. According to the Bragg diffraction condition, when the interplanar spacing satisfies a specific relationship, the X-rays diffract and are received by the detector. By measuring the offset of the diffraction peak position and combining it with the strain-stress constitutive relationship in elasticity, the normal stress value along the crystal surface normal direction at the measurement point is calculated. A measurement grid is uniformly arranged along the machined surface, and the row spacing and column spacing of the measurement grid are both set to five millimeters. The residual stress of all grid points is collected by moving the probe point by point. The measurement result of each grid point includes the normal stress component and shear stress component along three mutually orthogonal directions at that point. All the collected grid point data are saved as a set of discrete residual stress points. Each discrete residual stress point includes the two-dimensional spatial coordinates of the point on the machined surface and the corresponding stress tensor component value.

[0056] When spatially interpolating residual stress to obtain continuous residual stress, the stress tensor component values ​​of each discrete point are weighted and diffused to the surrounding area, with all discrete residual stress points as the center. The weight of the diffusion is determined according to the spatial distance between the target location and the discrete point; the closer the distance, the greater the weight, and the farther the distance, the smaller the weight. For any target location on the machined surface, all discrete residual stress points are traversed, and the distance between the target location and each discrete point is substituted into the radial basis function to calculate the corresponding weight coefficient. The stress tensor component values ​​of all discrete points are weighted and summed according to their weight coefficients. The resulting weighted sum is the interpolated stress tensor component value at the target location. The above interpolation operation is performed sequentially on all target locations on the machined surface. The resulting continuous residual stress covers the entire machined surface in the form of a continuous field, and the continuous residual stress at each location is completely described by six independent stress tensor components.

[0057] When extracting directional features from continuous residual stress, the stress tensor at each location is extracted from the continuous residual stress. The three principal stress values ​​and the corresponding three principal stress direction vectors of the stress tensor are calculated. The principal stress value with the largest absolute value is taken as the maximum principal stress value at that location, and the direction vector corresponding to the maximum principal stress value is taken as the principal direction vector of residual stress at that location. This principal direction vector of residual stress represents the direction in which the residual stress is strongest at that location. The direction of the principal direction vector of residual stress is determined by the projection direction of the direction vector on the machined surface plane. By traversing all locations covered by continuous residual stress, the principal direction vectors of residual stress extracted at each location are arranged according to their spatial coordinates to form a residual stress direction field covering the entire machined surface. This residual stress direction field has a direction vector at each location, which indicates the dominant direction of residual stress at that location.

[0058] When decomposing the initial toolpath trajectory into path segments, the straight line segments between each pair of adjacent path nodes are extracted sequentially according to the connection order of the path nodes in the initial toolpath trajectory as a path segment. Each path segment is uniquely determined by its start coordinates and end coordinates. The direction vector of the path segment points from the start to the end. All path segments are arranged according to their order in the initial toolpath trajectory to obtain the path segment sequence of the initial toolpath trajectory. Each path segment occupies a local area on the machining surface. This local area is composed of all spatial positions between the start coordinates and the end coordinates of the path segment.

[0059] When extracting the principal residual stress direction corresponding to the decomposed path segment from the residual stress direction field, for each path segment, sampling points are uniformly selected along the extension direction of the path segment within the local area occupied by the path segment. The number of sampling points is proportional to the length of the path segment. A sampling point is selected at a distance of one millimeter on each path segment. For each sampling point, the principal residual stress direction vector at the spatial coordinate position of the sampling point is read from the residual stress direction field. The principal residual stress direction vectors at all sampling points on the path segment are summed, and then the sum is normalized to obtain the principal residual stress direction corresponding to the path segment. This principal residual stress direction represents the average dominant residual stress direction within the area covered by the path segment.

[0060] When determining the feed direction of a path segment using the principal direction of residual stress as a constraint reference, the principal direction of residual stress corresponding to that path segment is taken as the reference direction of the feed direction of that path segment. The angle between the feed direction of the tool and the principal direction of residual stress when cutting along the path segment is set to zero degrees, that is, the tool feed direction is kept parallel to the principal direction of residual stress. When the direction of the principal direction of residual stress on the path segment is from the starting point to the ending point, the tool feed direction is set to the direction from the starting point to the ending point. When the direction of the principal direction of residual stress on the path segment is from the ending point to the starting point, the tool feed direction is set to the direction from the ending point to the starting point. The feed direction of each path segment is determined in the above way to make the tool feed direction and the principal direction of residual stress consistent in space.

[0061] When iteratively moving the path nodes of a path segment based on the directional deviation between the feed direction and the path segment, the original direction vector of the path segment points from the starting point to the ending point. The feed direction is compared with the original direction vector of the path segment, and the angle between the feed direction and the original direction vector of the path segment is calculated as the directional deviation angle. When the directional deviation angle is zero degrees, the direction of the path segment is consistent with the feed direction, and no directional adjustment is required. When the directional deviation angle is greater than zero degrees, the starting coordinates of the path segment are kept unchanged, and the ending coordinates are rotated around the starting coordinates according to the magnitude of the directional deviation angle. The rotation direction is from the original direction vector of the path segment to the feed direction, so that the direction of the line connecting the rotating ending coordinates and the starting coordinates is completely consistent with the feed direction, thus completing a single directional adjustment of the path segment.

[0062] After a direction adjustment is completed, the direction vector of the adjusted path segment is recalculated and compared with the feed direction. If the direction deviation angle is still greater than the preset angle threshold, the rotation operation of the endpoint coordinate is continued. The step size of each rotation is fixed at half of the direction deviation angle. Through multiple iterations, the feed direction is gradually approached until the direction deviation angle is less than the preset angle threshold, at which point the iteration stops. The angle threshold is set to one degree. After the above iterative movement, the endpoint coordinate of the path segment changes, and the direction of the path segment is consistent with the feed direction. After all path segments have completed the direction adjustment, the adjusted path segments are reconnected according to their original order in the initial toolpath trajectory. The endpoints of adjacent path segments are connected to the starting points of the next path segment, forming a complete continuous trajectory. This continuous trajectory is the toolpath trajectory after direction optimization.

[0063] The beneficial effects are as follows: by collecting the residual stress of metal parts and performing spatial interpolation and directional feature extraction, a residual stress direction field covering the entire machined surface is constructed. This field is used as a constraint to decompose the initial tool path trajectory into path segments and determine the feed direction of each path segment. This ensures that the tool feed direction is spatially consistent with the main direction of residual stress, overcoming the deficiency of lack of coordinated control between the feed direction and the residual stress field in existing technologies. By adjusting the direction of the path segments through iterative movement with the direction deviation angle set to zero, the cutting force direction is matched with the dominant direction of residual stress. This actively suppresses the machining deformation caused by the release of residual stress at the path planning level, avoiding the passive response mode of traditional methods that only perform deformation compensation after the fact. This significantly improves the machining deformation control capability and dimensional consistency level of complex metal parts such as thin-walled parts and frame beam structures.

[0064] In another feasible implementation, the residual stress of metal parts is collected using a stress detection device and the blind hole method is employed.

[0065] Specifically, a blind hole with a diameter of one to two millimeters is drilled at the measurement point on the machined surface of the metal part. The depth of the blind hole does not exceed one-third of the thickness of the machined surface. During the drilling process, a strain gauge installed around the blind hole measures the strain release at the measurement point in real time. The strain gauge contains three strain grates arranged along three mutually orthogonal directions. By measuring the resistance change of the three strain grates before and after drilling the blind hole, the three principal strain values ​​and the corresponding three principal strain directions at the measurement point are calculated. According to Hooke's law in elasticity, the principal strain values ​​are converted into principal stress values, completing the residual stress acquisition at the measurement point. A measurement grid is uniformly arranged along the machined surface. A blind hole is drilled at each grid point, and the strain release is recorded. All the collected grid point data are saved as a discrete set of residual stress points. This method has better portability and operability in on-site inspection scenarios of large workpieces where X-ray stress detectors are not applicable.

[0066] In another feasible implementation, when determining the feed direction of the path segment using the principal direction of residual stress as a constraint reference, the tool feed direction is not set to be parallel to the principal direction of residual stress, but rather set to be perpendicular to the principal direction of residual stress.

[0067] Specifically, the principal direction of residual stress corresponding to the path segment is used as the reference direction for the feed direction of that path segment. A direction perpendicular to this principal direction of residual stress is selected within the machining surface plane as the feed direction. When the principal direction of residual stress on the path segment points from the start to the end, the tool feed direction is set to be perpendicular to this direction and rotated 90 degrees clockwise. When the principal direction of residual stress on the path segment points from the end to the start, the tool feed direction is set to be perpendicular to this direction and rotated 90 degrees counterclockwise. The feed direction for each path segment is determined in this way, ensuring that the tool feed direction is spatially perpendicular to the principal direction of residual stress. This method is suitable for machining scenarios where the residual stress is predominantly compressive stress and has a large value. Under this condition, the cutting force direction is orthogonal to the principal direction of residual stress, and the disturbance of the residual stress field by the cutting force is less than in the parallel method. This avoids the situation where the cutting force is additionally superimposed on the principal direction of residual stress, leading to increased stress concentration.

[0068] S04: Determine the feasibility of the optimized toolpath trajectory and correct the toolpath trajectory according to the determination result until the preset consistency condition is met, and output the final planned path.

[0069] In this embodiment of the invention, when updating the thermal accumulation effect of the directional optimized toolpath trajectory, the path nodes in the directional optimized toolpath trajectory are rearranged according to their sequential connection order. The spatial coordinates of each path node on the machining surface are extracted. The instantaneous heat generation intensity value corresponding to each path node is read from the instantaneous heat generation intensity data. The material removal thickness value at the spatial location of each path node is read from the voxelized mesh of the cutting removal amount requirement. Following the node connection order of the directional optimized toolpath trajectory, heat accumulation is recursively performed node by node starting from the initial path node. The instantaneous heat generation intensity of the initial path node is directly used as the heat accumulation amount of that node. For each subsequent path node, the instantaneous heat generation intensity of that node is accumulated with the heat propagated to that node from all preceding path nodes. The heat propagation of each preceding node is equal to the instantaneous heat generation intensity of that preceding node multiplied by the heat transfer coefficient from the preceding node to the current node. After each recursion, the arithmetic mean of the heat accumulation of all calculated nodes is taken as the preceding accumulated temperature for the heat propagation calculation of subsequent nodes. The above recursion rules are followed sequentially along the node order of the optimized toolpath trajectory until the last path node is calculated to obtain the updated heat accumulation of all path nodes. The updated heat accumulation effect is obtained by aggregating and organizing all the updated heat accumulation.

[0070] When determining the feasibility of a toolpath using both the updated thermal accumulation effect and the cutting removal amount requirement as dual criteria, for each path segment in the directional optimized toolpath, the thermal accumulation value at the end of the path segment is read from the updated thermal accumulation effect and compared with a preset thermal accumulation safety threshold. Simultaneously, the maximum material removal thickness within the area covered by the path segment is read from the voxelized mesh of the cutting removal amount requirement and compared with a preset removal amount threshold. If the thermal accumulation value at the end of the path segment is less than or equal to the preset thermal accumulation safety threshold and the maximum material removal thickness within the area covered by the path segment is less than or equal to the preset removal amount threshold, the path segment is deemed to meet the feasibility conditions. If either of the above two conditions is not met, the path segment is deemed not to meet the feasibility conditions. The above determination operation is performed sequentially on all path segments in the directional optimized toolpath, and all path segments that do not meet the feasibility conditions are recorded.

[0071] When marking a path segment that does not meet the preset consistency condition in the judgment result as a path segment to be corrected, for a path segment that is judged not to meet the feasibility condition in the feasibility judgment, the path segment is marked as a path segment to be corrected. The marked path segments to be corrected include path segments with excessive heat accumulation and path segments with excessive removal. If the same path segment has both of the above-mentioned excessive conditions at the same time, it is still marked as a path segment to be corrected. The sequence number of all path segments to be corrected in the direction-optimized tool path trajectory and their excessive type are recorded in the correction list.

[0072] When performing topology correction on the path segment to be corrected, each path segment to be corrected is read sequentially from the list of path segments to be corrected. For path segments to be corrected that are marked due to excessive heat accumulation, one or more new path nodes are inserted between the start and end points of the path segment to be corrected. The spatial coordinates of the new path nodes are located on the line connecting the start and end points of the path segment to be corrected. The line connecting the start and end points is divided into several segments. The number of new path nodes is equal to the value of the heat accumulation multiple of the path segment to be corrected, rounded up. By inserting new path nodes, the original single path segment is split into multiple sub-path segments. After splitting, the length of each sub-path segment is shortened, and the heat propagation attenuation on shorter path segments is smaller. However, the instantaneous heat generation intensity of each sub-path segment remains unchanged. Due to the increase in the number of sub-path segments, the spatial distance between adjacent sub-path segments is reduced, and the thermal conductivity coefficient increases accordingly. However, the split sub-path segments increase the number of steps for heat accumulation. The overall heat accumulation effect is dispersed through path segment splitting. For a path segment marked as needing correction due to excessive removal, a parallel sub-path segment is generated by offsetting a preset distance vertically between the start and end points of the path segment to be corrected. The original single path segment is split into two parallel path segments, one being the original path segment and the other being the parallel sub-path segment. The two parallel path segments each undertake half of the removal amount of the original path segment, so that the removal amount of each path segment is reduced to below the preset removal amount threshold. The offset distance is half the tool diameter, ensuring that there is no interference between the two parallel path segments and that the cutting area can completely cover the original machining range.

[0073] When replacing the corresponding path segment to be corrected in the toolpath with the corrected path segment, the path segment to be corrected is removed from the toolpath where it is located. The multiple sub-path segments generated after topology correction are inserted into the positions of the original path segments in the order from the start point to the end point of the original path segments. The multiple sub-path segments are connected end to end. The start point of the first sub-path segment is the start point of the original path segment to be corrected, and the end point of the last sub-path segment is the end point of the original path segment to be corrected. After the insertion is completed, the updated toolpath is obtained.

[0074] Using the updated toolpath trajectory as input, the process of updating the thermal accumulation effect, determining feasibility, and correcting the topology is repeated until the feasibility determination results of all path segments meet the preset consistency conditions. When outputting the final planned path, the updated toolpath trajectory is used as the new input. The thermal accumulation of all path nodes is recalculated along the node connection order of the updated toolpath trajectory to obtain the updated thermal accumulation effect. Using the updated thermal accumulation effect and the required cutting removal amount as dual judgment criteria, the feasibility of each path segment in the updated toolpath trajectory is determined again. Path segments that still do not meet the preset consistency conditions are marked as new path segments to be corrected. Topology correction is performed on the new path segments to be corrected, and the corrected path segments are replaced. The process of iterating through the updated toolpath trajectory continues until the feasibility determination results of all path segments meet the preset consistency conditions. Then, the iteration stops and the current toolpath trajectory is output as the final planned path. The preset consistency conditions are that all path segments in the directional optimized toolpath trajectory meet the feasibility determination conditions, that is, the heat accumulation value at the end of each path segment is less than or equal to the preset heat accumulation safety threshold, and the maximum material removal thickness in the area covered by each path segment is less than or equal to the preset removal threshold. When there are no path segments to be corrected in the current toolpath trajectory, the toolpath trajectory is the final planned path that meets the preset consistency conditions. The final planned path is then output to the CNC system to drive the tool to perform cutting.

[0075] The beneficial effects are as follows: by using the updated thermal accumulation effect and the cutting removal amount requirement as dual judgment criteria to determine the feasibility of the directional optimized tool path trajectory, the path segments that do not meet the consistency conditions are marked as path segments to be corrected. Differentiated topology correction strategies of path segment splitting and parallel path generation are adopted for the two cases of excessive thermal accumulation and excessive cutting removal amount, respectively. This overcomes the defects of the lack of closed-loop verification and correction mechanism after path generation in the existing technology. Through iterative loop, the path segments that do not meet the conditions are continuously corrected to meet the conditions until all path segments pass the feasibility judgment. This makes the final output planned path not only meet the path length and direction constraints at the geometric level, but also meet the physical feasibility requirements at the thermal accumulation control and cutting removal amount allocation levels, which significantly improves the engineering practicality of the tool path trajectory and the stability of the machining process.

[0076] In another feasible implementation, when updating the thermal accumulation effect of the toolpath trajectory after direction optimization, the recursive method of accumulating heat from all preceding nodes is not used. Instead, a simplified recursive method that only considers the immediate preceding nodes is used.

[0077] Specifically, the path nodes in the optimized toolpath trajectory are rearranged according to their sequential connection order. The first path node is used as the starting node, and its instantaneous heat generation intensity is directly used as the heat accumulation of that node. For each subsequent path node, only its own instantaneous heat generation intensity is added to the heat propagated from the previous path node. The heat propagated from the previous path node is equal to the instantaneous heat generation of the previous path node multiplied by the heat transfer coefficient from the previous path node to the current path node. The heat propagated from earlier nodes is not added. This simplified calculation is performed sequentially along the node order of the optimized toolpath trajectory until the last path node, obtaining the simplified heat accumulation of all path nodes. The updated heat accumulation effect is then obtained by aggregating and organizing all the simplified heat accumulations. This method significantly reduces the computational load when the total number of path nodes is large and the heat accumulation effect needs to be updated repeatedly during iterative correction, making it suitable for online correction scenarios requiring rapid convergence.

[0078] In another feasible implementation, for path segments marked as needing correction due to excessive removal, instead of splitting the removal amount by generating parallel sub-path segments, the removal amount is reduced per unit time by adjusting the feed speed of the path segment.

[0079] Specifically, the ratio of the maximum material removal thickness of the path segment to be corrected to a preset removal threshold is obtained. This ratio is used as a feed rate adjustment coefficient. The original feed rate of the path segment to be corrected is divided by this adjustment coefficient to obtain the corrected feed rate. This reduces the cutting area swept by the tool per unit time to the ratio of the original removal threshold to the maximum material removal thickness, thereby reducing the removal amount of the path segment to below the preset removal threshold without changing the spatial position and direction of the path segment. This method satisfies the removal consistency condition by adjusting the feed rate rather than changing the path geometry when the geometric space of the machining area is limited and parallel sub-path segments cannot be generated to avoid interference between tools.

[0080] like Figure 2 The diagram shown is a functional block diagram of a metal parts cutting system based on path planning, provided in an embodiment of the present invention.

[0081] The metal parts cutting system based on path planning described in this invention can be installed in electronic devices. Depending on the functions implemented, the metal parts cutting system based on path planning may include a node layout module, a path generation module, a path adjustment module, and a feasibility determination module. The module described in this invention can also be called a unit, which refers to a series of computer program segments that can be executed by the processor of an electronic device and can perform a fixed function, and is stored in the memory of the electronic device.

[0082] In this embodiment, the functions of each module / unit are as follows:

[0083] The node layout module is used to perform a fusion calculation of the cutting removal amount requirement of the metal parts and the surface geometric features, and to lay out the nodes of the metal parts according to the calculated density field.

[0084] The path generation module is used to construct a topology connection scheme based on the path nodes of the metal parts, and to perform thermal accumulation effect analysis on the topology connection scheme according to the process parameters and material properties of the metal parts. The target topology connection scheme is selected with path length and thermal accumulation effect as joint evaluation index, and the initial tool path trajectory is output.

[0085] The path adjustment module is used to plan the initial tool path trajectory based on the residual stress direction field of the metal component as a condition constraint, obtain the feed direction, and adjust the direction of the initial tool path trajectory according to the feed direction.

[0086] The feasibility determination module is used to determine the feasibility of the optimized tool path trajectory and correct the tool path trajectory according to the determination result until the preset consistency condition is met, and output the final planned path.

[0087] In the several embodiments provided by this invention, it should be understood that the disclosed methods and systems can be implemented in other ways. For example, the system embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and other division methods may be used in actual implementation.

[0088] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0089] Furthermore, the functional modules in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or in the form of hardware plus software functional modules.

[0090] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0091] This application embodiment can acquire and process relevant data based on artificial intelligence technology. Artificial intelligence is the theory, method, technology, and application system that uses digital computers or machines controlled by digital computers to simulate, extend, and expand human intelligence, perceive the environment, acquire knowledge, and use that knowledge to obtain optimal results.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for machining metal parts based on path planning, characterized in that, The method includes: S01: The cutting removal amount requirement of the metal parts is calculated by integrating the surface geometric features, and the nodes of the metal parts are arranged according to the calculated density field. S02: Based on the initial path nodes of the metal parts, a topology connection scheme is constructed. According to the process parameters and material properties of the metal parts, the thermal accumulation effect of the topology connection scheme is analyzed. Using path length and thermal accumulation effect as joint evaluation indicators, a target topology connection scheme is selected, and the initial tool path trajectory is output, including: The density mapping between the surface geometry and the required amount of material removed during cutting is performed to obtain the intensity distribution of the metal parts. Based on the intensity distribution of the points, a density field is constructed; Based on the density field, a threshold determination is made on the processed surface of the metal parts. Areas with density field values ​​higher than a preset threshold are marked as high-density areas, and areas with density field values ​​lower than a preset threshold are marked as low-density areas. The high-density deployment area is densified, and the low-density deployment area is sparsed to obtain the initial path nodes of the metal parts. S03: Using the residual stress direction field of the metal component as a constraint, the initial tool path trajectory is planned to obtain the feed direction, and the initial tool path trajectory is adjusted according to the feed direction, including: Based on the domain relationships of the initial path nodes, the initial path nodes are reconstructed to obtain candidate topology connection schemes; Using the process parameters and material properties of the metal components as constraints, the thermal accumulation effect of the candidate topology connection scheme is analyzed. The path lengths of the candidate topology connection schemes are statistically analyzed, and the heat accumulation effect corresponding to the candidate topology connection scheme and the path length are used as a joint evaluation index to comprehensively evaluate the cost of the candidate topology connection scheme and obtain the cost value of the candidate topology connection scheme. The candidate topology connection scheme with the lowest replacement value is selected as the target topology connection scheme. According to the path node connection order defined by the target topology connection scheme, the path nodes are connected in series to output the initial tool path trajectory. S04: Determine the feasibility of the optimized toolpath trajectory and correct the toolpath trajectory according to the determination result until the preset consistency condition is met, and output the final planned path.

2. The method for machining metal parts based on path planning as described in claim 1, characterized in that, Before the calculation of the required amount of material removed by cutting the metal parts and the surface geometric features, the following steps are also included: The surface of the three-dimensional model of the metal parts is discretized to obtain the surface mesh model of the metal parts; Curvature analysis is performed on the surface mesh model to obtain the surface geometric features of the metal parts; The spatial positions of the three-dimensional model and the blank model of the metal parts are registered. Boolean difference operation is performed on the registered model to obtain the required amount of material removed by cutting the metal parts.

3. The method for machining metal parts based on path planning as described in claim 1, characterized in that, The step of analyzing the thermal accumulation effect of the candidate topology connection schemes using the process parameters and material properties of the metal components as constraints includes: Obtain the spatial location of the path nodes in the candidate topology connection scheme and the cutting removal amount corresponding to the path nodes; Using the process parameters and the amount of material removed as input, the instantaneous heat generation intensity of the path nodes is statistically analyzed. Based on the spatial location, the spatial distance between the path nodes is calculated; Using the spatial distance as the basis for heat propagation attenuation, the path resistance coefficient is determined based on the thermal conductivity and thermal diffusion characteristic length in the material properties. Based on the path resistance coefficient, the spatial distance, and the instantaneous heat generation intensity, the proportion of residual heat when heat at a path node propagates to an adjacent path node is statistically analyzed, and the thermal conductivity coefficient is output.

4. The method for machining metal parts based on path planning as described in claim 3, characterized in that, The step of analyzing the thermal accumulation effect of the candidate topology connection scheme using the process parameters and material properties of the metal components as constraints further includes: Starting from the initial path node, the heat accumulation is recursively calculated node by node, and after each recursion, the average heat accumulation of the calculated nodes is statistically analyzed to obtain the previous accumulated temperature. Based on the instantaneous heat generation intensity, the spatial distance, the thermal conductivity, the process parameters, the material properties, and the preceding cumulative temperature, the candidate topology connection scheme is recursively calculated node by node to obtain the cumulative heat amount; The accumulated heat is aggregated and organized to obtain the accumulated heat effect of the candidate topology connection scheme.

5. The method for machining metal parts based on path planning as described in claim 4, characterized in that, The step of performing a node-by-node recursion on the candidate topology connection scheme to obtain the heat accumulation includes: The formula for calculating the accumulated heat is as follows: ； In the formula, For the first Heat accumulation at each path node For the first Instantaneous heat generation intensity at each path node For the first Instantaneous heat generation intensity at each path node For the first The path node and the first Spatial distance between path nodes The characteristic length of thermal diffusion of the material. For the first The preceding cumulative temperature at each path node The preset ambient reference temperature, For tool feed rate, The preset reference feed rate, The preset spatial distance attenuation coefficient, This is the path hindrance coefficient. For the first The path node and the first The length of the path segment between each path node.

6. The method for machining metal parts based on path planning as described in claim 1, characterized in that, The process of planning the initial toolpath trajectory based on the residual stress direction field of the metal component as a constraint to obtain the feed direction, and adjusting the direction of the initial toolpath trajectory according to the feed direction, includes: The residual stress of the metal parts is collected using stress testing equipment; Spatial interpolation is performed on the residual stress to obtain continuous residual stress; The directional features of the continuous residual stress are extracted, and a residual stress direction field is constructed based on the obtained residual stress direction vector. The initial toolpath trajectory is decomposed into path segments, and the principal direction of residual stress corresponding to the decomposed path segments is extracted from the residual stress direction field. The feed direction of the path segment is determined using the principal direction of residual stress as a constraint reference. Based on the directional deviation between the feed direction and the path segment, the path nodes of the path segment are iteratively moved to output the optimized tool path trajectory.

7. The method for machining metal parts based on path planning as described in claim 6, characterized in that, The process involves determining the feasibility of the optimized toolpath trajectory and correcting it based on the determination result until a preset consistency condition is met, ultimately outputting the final planned path. This includes: The thermal accumulation effect of the optimized toolpath trajectory is updated. The feasibility of the tool path trajectory is determined by using the updated heat accumulation effect and the required amount of material removed as dual criteria. The path segments that do not meet the preset consistency conditions in the judgment results are marked as path segments to be corrected; Perform topology correction on the path segment to be corrected, and replace the corresponding path segment to be corrected in the tool path trajectory with the corrected path segment to obtain the updated tool path trajectory. Using the updated toolpath trajectory as input, the process of updating the thermal accumulation effect, determining feasibility, and correcting the topology is repeated until the feasibility determination results of all path segments meet the preset consistency conditions, and the final planned path is output.

8. A metal parts cutting system based on path planning, characterized in that, The system for implementing the path planning-based metal part cutting method of claim 1 includes: The node layout module is used to perform a fusion calculation of the cutting removal requirements and surface geometric features of the metal parts, and to lay out the nodes of the metal parts according to the calculated density field. The path generation module is used to construct a topology connection scheme based on the path nodes of the metal parts, and to perform thermal accumulation effect analysis on the topology connection scheme according to the process parameters and material properties of the metal parts. The target topology connection scheme is selected with path length and thermal accumulation effect as joint evaluation index, and the initial tool path trajectory is output. The path adjustment module is used to plan the initial tool path trajectory based on the residual stress direction field of the metal parts as a condition constraint, obtain the feed direction, and adjust the direction of the initial tool path trajectory according to the feed direction. The feasibility determination module is used to determine the feasibility of the optimized toolpath trajectory and correct the toolpath trajectory according to the determination result until the preset consistency conditions are met, and output the final planned path.

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