A path planning method for long carbon fiber composite material free-form surface partition processing

Abstract

The application provides a path planning method for long carbon fiber composite material free-form surface partition processing, which is used for long carbon fiber composite material free-form surface processing, realizes partition processing according to a given tool axis vector on a surface to be processed, effectively reduces the rotation times of each axis of a five-axis machine tool, reduces the generation of tool marks, improves the tool walking efficiency and ensures the surface processing quality. The path planning method of the application has simple logic and small calculation amount, can realize path planning of free-form surfaces with various fiber orientations and has wide adaptability. The path planning method of the application provides a solution for long carbon fiber composite material free-form surface partition processing, but the processing material is not limited to long carbon fiber, and the path planning strategy is not limited to five-axis machine tool milling processing, and can be extended to path planning technologies of different anisotropic materials and different processing technologies.

Description

Technical Field

[0001] This invention belongs to the field of computer-aided manufacturing (CAM) technology, specifically relating to a path planning method for the partitioning of freeform surfaces of long carbon fiber composite materials. Background Technology

[0002] Carbon fiber composites have high specific modulus and specific strength, and are easy to process. When combined with matrices such as resin, ceramics, and metals, carbon fiber composites have high strength, high fatigue resistance, light weight, high temperature resistance, and corrosion resistance. Therefore, they are widely used in wind power generation, vehicles, military industry, aerospace and other fields.

[0003] Long carbon fiber composites are a type of carbon fiber composite material made by impregnation of reinforcing carbon fibers and thermoplastic polymers. By controlling the fiber orientation, the anisotropy of the material can be achieved, thereby enhancing mechanical properties in a specific direction.

[0004] The freeform surface of long carbon fiber composite material is milled using a five-axis machine tool. Considering the internal fiber orientation of the material, the machining tool position point and tool axis vector are generated in the parameter domain space by limiting the lateral step size, residual height, and bow height error. Using the traditional zigzag machining path, the included angle between adjacent tool axis vectors varies greatly. The rotation of each axis of the five-axis machine tool reduces machining efficiency, resulting in tool marks on the surface and thus reducing machining quality.

[0005] Current academic strategies for processing freeform surfaces of long carbon fiber composites focus on the geometric properties of the processed surface, lacking a method that combines optimization of the tool axis vector direction. When processing composites with complex carbon fiber orientations, it is difficult to simultaneously achieve superior surface finish and higher processing efficiency. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a path planning method for partitioning freeform surfaces of long carbon fiber composite materials. This path planning method optimizes the partitioning path based on the tool axis vector method, has a fast execution speed, is applicable to free surfaces with different carbon fiber orientations, and achieves high processing quality and high processing efficiency.

[0007] A path planning method for partitioning freeform surfaces of long carbon fiber composites includes the following steps:

[0008] (1) Obtain the two-dimensional parameter space of the surface to be processed and the tool axis vector of each node in the parameter space, and set the segmentation threshold at the same time;

[0009] (2) Divide the parameter space into multiple regions according to the tool axis vector of the node and the segmentation threshold, and number the different regions and their nodes so that the regions and all nodes within them have the same number.

[0010] (3) Establish multiple sets that correspond one-to-one with multiple regions, determine the outline points of each region, and store them into their respective sets;

[0011] (4) Rearrange the contour points of each region and update the corresponding set. The rearranged contour points form the contour.

[0012] (5) For each region, take the contour point with the smallest ordinate in its corresponding set as the outer contour and the rest as the inner contour. Then, according to the principle of reverse for the outer contour and forward for the inner contour, reverse the order of the contour points of the inner contour.

[0013] (6) For each multi-connected region containing an inner contour, starting from the inner contour with the smallest ordinate in its corresponding set, find four key nodes, and divide the corresponding region according to the four key nodes to obtain a single-connected region that does not contain an inner contour.

[0014] (7) Split each simply connected region until each simply connected region can be lifted by using a zigzag path;

[0015] (8) Generate zigzag paths in each segmented region, connect the first and last zigzag paths of each region as the lifting path, and generate machining G-code.

[0016] In step (1) above:

[0017] As a preferred approach, a T-spline surface modeling method is used to represent the two-dimensional parameter space of the surface to be processed. The coordinates of each node in the parameter space are represented by (s,t), where s is the abscissa and t is the ordinate.

[0018] The tool axis vectors at each node are all unit vectors, obtained by fiber orientation, machining residual height, tool tilt angle, and the number of unidirectional nodes in the parameter space grid (the number of nodes on each coordinate axis of the parameter space).

[0019] In step (2) above:

[0020] As a preferred option, the specific operation process of step (2) is as follows:

[0021] 2.1. Using the parameter space as the current region, take the node with the smallest x-coordinate among the nodes with the smallest y-coordinate as the starting node and number it, and use the starting node as the current node.

[0022] 2.2 Perform a depth-first traversal of the current node in all four directions (positive and negative) along both coordinate axes. Using any untraversed direction as the current direction, calculate the angle between the current node and the tool axis vector of the next node in the current direction, and determine the magnitude of this angle relative to the segmentation threshold.

[0023] If the included angle is less than the segmentation threshold, then mark the next node with the same number as the current node, and use the next node as the current node, repeating step 2.2;

[0024] If the included angle is greater than the segmentation threshold, stop traversing, return to the current node, select other untraversed directions for traversal, and continue traversing until all four directions have been traversed.

[0025] 2.3 Repeat step 2.2 until there are no more adjacent nodes in the current region whose angle between the cutter axis vector and the current node's cutter axis vector is less than the segmentation threshold, thus completing the division of a region;

[0026] 2.4. Take the parameter space from the region divided in step 2.3 as the current region, and repeat steps 2.1 to 2.3 until all nodes have been traversed, thus completing the region division of the parameter space; during this period, each time step 2.1 is repeated, the number of the corresponding starting node is incremented by one.

[0027] As a further preferred option, the formula for calculating the angle θ between the current node and the tool axis vector of the next node in any untraversed direction is:

[0028]

[0029] In the formula, and These are the tool axis vectors for the current node and its next node, respectively.

[0030] In step (3) above:

[0031] Preferably, in step (3), the method for determining the contour points of any region is as follows:

[0032] 3.1. Take any region as the current region, and take the node with the smallest x-coordinate among the nodes with the smallest y-coordinate in the current region as the input, and take it as the current node;

[0033] 3.2. Perform a depth-first traversal of the current node in all four directions (positive and negative) along both coordinate axes. Using any untraversed direction as the current direction, determine whether the next node of the current node in the current direction is located within the current region:

[0034] If not, stop traversing in the current direction, return to the current node, and traverse the other untraversed directions;

[0035] If so, then determine whether the next node of the current node is a contour point:

[0036] If not, stop traversing in the current direction, return to the current node, and traverse the other untraversed directions;

[0037] If so, store the next node in the set corresponding to the current region, and use the next node as the current node, repeating step 3.2.

[0038] As a further optimization, it is determined whether the next node is located within the current region by judging whether the current node has the same number as the next node.

[0039] As a further optimization, the method for determining whether a point in the current region is a contour point is as follows:

[0040] For the current node, if there is a node that is not in the current region among its eight adjacent nodes in the positive and negative directions that are parallel to the two coordinate axes and at a 45° angle to the two coordinate axes, then the current node is a contour point; otherwise, the current node is not a contour point.

[0041] The positive and negative directions that form a 45° angle with the two coordinate axes are the four directions that form a 45° angle with the two coordinate axes and are away from the current node.

[0042] In step (4) above:

[0043] In this step, the contour of each region may contain at least one inner contour, or it may not contain an inner contour. Regions containing inner contours are considered multi-connected regions, and regions not containing inner contours are considered simply connected regions.

[0044] Preferably, in step (4), the specific process of rearranging the contour points of each region is as follows:

[0045] 4.1. Take any unrearranged region of a contour point as the current region, and take the contour point with the smallest x-coordinate among the nodes with the smallest y-coordinate in the current region as the contour starting point. Determine the output direction of the contour starting point and use it as the input direction of the next contour point of the contour starting point in the output direction.

[0046] 4.2. Take the next contour point as the current contour point, and determine the output direction of the current contour point according to the input direction of the current contour point and the number of its adjacent contour points, and obtain the input direction of the next contour point of the current contour point in the output direction.

[0047] 4.3 Repeat step 4.2 until all contour points in the current area have been processed;

[0048] 4.4 Repeat steps 4.1 to 4.3 until all regions have completed the rearrangement of outline points.

[0049] As a further preferred method, the output direction of the contour starting point is determined as follows:

[0050] First, search from the starting point of the contour in the positive direction of the horizontal coordinate. If a contour point exists in the current area, the positive direction of the horizontal coordinate is used as the output direction of the starting point of the contour; if it does not exist, the positive direction of the vertical coordinate is used as the output direction of the starting point of the contour.

[0051] As a further preferred method, the output direction of the current contour point is determined based on the input direction of the current contour point and the number of its adjacent contour points as follows:

[0052] The number of contour points adjacent to the current contour point is divided into four cases: 1, 2, 3, and 4. The corresponding current contour points are designated as one-way points, two-way points, three-way points, and four-way points, respectively. The output direction of the current contour point under different cases is as follows:

[0053] The output direction of a point is opposite to its input direction.

[0054] The output direction of a bidirectional point is the same as its input direction.

[0055] For a three-way point, if the adjacent node in the direction of clockwise rotation of 90° from its input direction is the contour point of the current region, then the direction of clockwise rotation of 90° from the input direction of the three-way point is taken as its output direction; otherwise, its output direction is the same as its input direction.

[0056] The output direction of a four-way point is 90° clockwise from its input direction.

[0057] In step (6) above:

[0058] Preferably, if the multi-connected region contains multiple inner contours, the segmentation order of the multiple inner contours is as follows: first, segment out the inner contour containing the node with the smallest x-coordinate among the nodes with the smallest y-coordinates, and then segment out all the inner contours in the multi-connected region in this order.

[0059] Preferably, in step (6), any unsegmented multi-connected region containing an inner contour is taken as the current region, and its corresponding set is taken as the current set. Starting from the inner contour with the smallest ordinate in the current set, four key points are found, and the current region is segmented according to the key points as follows:

[0060] 6.1. Take the node with the smallest x-coordinate among the nodes with the smallest y-coordinate of the inner contour in the current set as the starting point, and traverse according to the order of the contour points. Take the first node whose y-coordinate is different from the starting point as the first key point.

[0061] 6.2. Traverse from key point one in the positive direction of the horizontal axis, and take the first contour point on the inner contour of the current region as key point two.

[0062] 6.3. The key point is traversed in the negative direction of the horizontal coordinate until a contour point on the outer contour of the current region is encountered. If the adjacent contour point in the negative direction of the vertical coordinate of the contour point is also located on the outer contour, then the contour point is regarded as the third key point.

[0063] 6.4. Traverse the second key point in the positive direction of the horizontal coordinate until a contour point on the outer contour of the current region is encountered. The adjacent contour point in the negative direction of the vertical coordinate of this contour point is also located on the outer contour. This contour point is taken as the fourth key point.

[0064] 6.5 Connect key points one and three, key points two and four, the adjacent contour points of key point four in the negative direction of the vertical coordinate and the adjacent contour points of key point two in the negative direction of the vertical coordinate, the adjacent contour points of key point three in the negative direction of the vertical coordinate and the adjacent contour points of key point one in the negative direction of the vertical coordinate to form multiple new contour regions.

[0065] 6.6 If the new contour region formed in step 6.5 still contains the inner contour, repeat steps 6.1 to 6.5 until the new contour region no longer contains the inner contour.

[0066] Preferably, in step (7), the specific process of segmenting any unsegmented simply connected region as the current region until using a zigzag path will not cause a tool lifting error is as follows:

[0067] 7.1 Traverse the contour points of the current region in the order of the contour points until a contour point is found that satisfies the following conditions: the previous contour point of the contour point is located on the positive (negative) side of the vertical coordinate of the contour point, and the next contour point is located on the negative (positive) side of the horizontal coordinate of the contour point. Then, the contour point is regarded as the first key point.

[0068] 7.2. Search for the first key point in the negative (positive) direction of the horizontal axis according to the order of the contour points until a contour point appears. If the next contour point is located on the side of the positive (negative) direction of the vertical axis of the contour point, then let the contour point be the second key point.

[0069] 7.3 The second key point traverses in the negative (positive) direction of the horizontal coordinate until it encounters the first contour point of the current region, and then uses that contour point as the third key point;

[0070] 7.4. The first key point is to traverse in the positive (negative) direction of the horizontal axis until the first contour point of the current region is encountered, and then the contour point is used as the fourth key point.

[0071] 7.5 Connect the first key point and the fourth key point, the second key point and the third key point, the adjacent contour points in the positive (negative) direction of the first key point's ordinate with the adjacent contour points in the positive (negative) direction of the fourth key point's ordinate, and the adjacent contour points in the positive (negative) direction of the third key point's ordinate with the adjacent contour points in the positive (negative) direction of the second key point's ordinate, and form new contours to complete the segmentation of the simply connected region.

[0072] As a preferred option, in step (8), for each region, the node with the smallest horizontal coordinate among the nodes with the smallest vertical coordinate is taken as the starting point, and the zigzag path is obtained by stacking the nodes row by row along the vertical coordinate direction.

[0073] The path planning method of the present invention for the partitioned machining of free-form surfaces of long carbon fiber composite materials achieves partitioned machining based on the given tool axis vector on the surface to be machined, thereby reducing the number of rotations of each axis of the five-axis machine tool and improving the machining feed efficiency.

[0074] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0075] (1) The path planning method proposed in this invention generates partitioned machining paths based on the tool axis vector, which effectively reduces the tool marks caused by the rotation of each axis of the five-axis machine tool and can greatly improve machining efficiency while ensuring surface machining quality.

[0076] (2) The path planning method proposed in this invention is simple in logic and has a small amount of computation; it can realize path planning of free surfaces (curved surfaces) with various fiber orientations and has wide adaptability.

[0077] (3) The path planning method proposed in this invention provides a solution for the partitioned processing of freeform surfaces of long carbon fiber composite materials. However, the processing material is not limited to long carbon fiber, and the path planning strategy is not limited to five-axis machine tool milling. It can be extended to path planning technology for different anisotropic materials and different processing techniques. Attached Figure Description

[0078] Figure 1 This is a flowchart illustrating the path planning method for partitioning the freeform surface of long carbon fiber composite materials according to an embodiment of the present invention.

[0079] Figure 2 This is a schematic diagram illustrating the steps of progressively dividing the parameter space using a depth-first traversal method.

[0080] Figure 3 This is a schematic diagram for determining contour points;

[0081] Figure 4 A schematic diagram showing the output direction for the starting point of the contour;

[0082] Figure 5 Output a direction lookup diagram for the current contour point;

[0083] Figure 6 This is a schematic diagram of multi-connected region segmentation;

[0084] Figure 7 This is a schematic diagram of a simply connected region segmentation.

[0085] Figure 8 A schematic diagram illustrating the determination of key nodes during the segmentation of a simply connected region;

[0086] Figure 9 This is a schematic diagram of the surface model to be machined and the obtained tool axis vector in an application example;

[0087] Figure 10 This is a schematic diagram of the partitioning results of the surface model to be processed in the application example;

[0088] Figure 11 This is a schematic diagram showing the partitioning path generation result of the surface model to be processed in the application example;

[0089] Figure 12 This is a schematic diagram of the simulation results of the partitioning of the surface model to be processed in the application example;

[0090] Figure 13 This is a diagram showing the non-partitioned processing result of the surface model to be processed in the application example;

[0091] Figure 14 This is a diagram showing the partitioned processing results of the surface model to be processed in the application example. Detailed Implementation

[0092] The present invention is described below with reference to the accompanying drawings and preferred embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not limited to the specific embodiments.

[0093] like Figure 1 As shown, a path planning method for partitioning freeform surfaces of long carbon fiber composite materials includes the following steps:

[0094] 1. Obtain the two-dimensional parameter space of the surface to be machined and the tool axis vector of each node in the parameter space. At the same time, set the segmentation threshold θ0.

[0095] The T-spline surface modeling method is used to represent the two-dimensional parameter space of the surface to be processed. The coordinates of each node in the parameter space are represented by (s,t), where s is the abscissa and t is the ordinate. The positive and negative directions of the abscissa are the right and left directions, respectively, and the positive and negative directions of the ordinate are the up and down directions, respectively. The tool axis vector on each node is a unit vector.

[0096] 2. Based on the tool axis vector of the node The parameter space is divided into multiple regions by the segmentation threshold θ0, and different regions and their nodes are numbered so that the regions and all nodes within them have the same number.

[0097] like Figure 2 As shown, the specific operation steps are as follows:

[0098] 2.1. Using the parameter space as the current region, take the node with the smallest x-coordinate among the nodes with the smallest y-coordinate as the starting node and number it, and use the starting node as the current node.

[0099] 2.2 Perform a depth-first traversal of the current node along both positive and negative axes, taking any untraversed direction as the current direction, and calculate the tool axis vector of the current node. Tool axis vector of the next node in the current direction The angle between the two points is determined, and the magnitude of this angle θ is compared with the segmentation threshold θ0.

[0100] If the included angle θ is less than the segmentation threshold θ0, then the next node is marked with the same number as the current node, and the next node is used as the current node, and step 2.2 is repeated;

[0101] If the included angle θ is greater than the segmentation threshold θ0, stop the traversal, return to the current node, select other untraversed directions for traversal, and continue traversing until all four directions have been traversed.

[0102] tool axis vector of the current node The tool axis vector of the next node in any untraversed direction

[0103] The formula for calculating the included angle θ is:

[0104]

[0105] 2.3 Repeat step 2.2 until there are no more adjacent nodes in the current region whose angle between the cutter axis vector and the current node's cutter axis vector is less than the segmentation threshold, thus completing the division of a region;

[0106] 2.4. Take the parameter space from the region divided in step 2.3 as the current region, and repeat steps 2.1 to 2.3 until all nodes have been traversed, thus completing the region division of the parameter space; during this period, each time step 2.1 is repeated, the number of the corresponding starting node is incremented by one.

[0107] 3. Establish multiple sets that correspond one-to-one with multiple regions, determine the contour points of each region, and store them into their respective sets.

[0108] For any given region, the method for determining its contour points is as follows:

[0109] 3.1. Take any region as the current region, and take the node with the smallest x-coordinate among the nodes with the smallest y-coordinate in the current region as the input, and take it as the current node;

[0110] 3.2. Perform a depth-first traversal of the current node in all four directions (positive and negative) along both coordinate axes. Using any untraversed direction as the current direction, determine whether the next node of the current node in the current direction is located within the current region:

[0111] If not, stop traversing in the current direction, return to the current node, and traverse the other untraversed directions;

[0112] If so, then determine whether the next node of the current node is a contour point:

[0113] If not, stop traversing in the current direction, return to the current node, and traverse the other untraversed directions;

[0114] If so, store the next node in the set corresponding to the current region, and use the next node as the current node, repeating step 3.2.

[0115] Specifically, it is determined whether the next node is located within the current region by checking whether the current node has the same number as its next node.

[0116] like Figure 3 As shown, the following method is used to determine whether the next node of the current node is a contour point:

[0117] For the current node, if any of its eight adjacent nodes in the positive and negative directions parallel to the two coordinate axes and at a 45° angle to the two coordinate axes are not in the current region, then the current node is a contour point; otherwise, the current node is not a contour point. The positive and negative directions at a 45° angle to the two coordinate axes are the four directions along the two coordinate axes at a 45° angle and away from the current node.

[0118] 4. Rearrange the contour points of each region and update the corresponding set. The rearranged contour points form the contour.

[0119] In this step, the contour of each region may contain at least one inner contour, or it may not contain an inner contour. Regions containing inner contours are considered multi-connected regions, and regions not containing inner contours are considered simply connected regions.

[0120] The specific steps are as follows:

[0121] 4.1. Take any unrearranged region of a contour point as the current region, and take the contour point with the smallest x-coordinate among the nodes with the smallest y-coordinate in the current region as the contour starting point. Determine the output direction of the contour starting point and use it as the input direction of the next contour point of the contour starting point in the output direction.

[0122] like Figure 4 As shown, the output direction of the contour starting point is determined in the following way:

[0123] First, search from the starting point of the contour in the positive direction of the horizontal coordinate (shown as the right direction or to the right in the figure). If a contour point exists in the current area, the positive direction of the horizontal coordinate is used as the output direction of the starting point of the contour (shown as the initial direction in the figure); if it does not exist, the positive direction of the vertical coordinate (shown as the upward direction or up direction in the figure) is used as the output direction of the starting point of the contour.

[0124] 4.2. Take the next contour point as the current contour point, and determine the output direction of the current contour point according to the input direction of the current contour point and the number of its adjacent contour points, and obtain the input direction of the next contour point of the current contour point in the output direction.

[0125] like Figure 5 As shown, the output direction of the current contour point is determined as follows:

[0126] The number of contour points adjacent to the current contour point is divided into four cases: 1, 2, 3, and 4. The corresponding current contour points are designated as one-way points, two-way points, three-way points, and four-way points, respectively. The output direction of the current contour point under different cases is as follows:

[0127] The output direction of a point is opposite to its input direction.

[0128] The output direction of a bidirectional point is the same as its input direction.

[0129] For a three-way point, if the adjacent node in the direction of clockwise rotation of 90° from its input direction is the contour point of the current region, then the direction of clockwise rotation of 90° from the input direction of the three-way point is taken as its output direction; otherwise, its output direction is the same as its input direction.

[0130] The output direction of a four-way point is 90° clockwise from its input direction.

[0131] 4.3 Repeat step 4.2 until all contour points in the current area have been processed;

[0132] 4.4 Repeat steps 4.1 to 4.3 until all regions have completed the rearrangement of contour points.

[0133] 5. For each region, take the contour containing the contour point with the smallest ordinate in its corresponding set as the outer contour and the rest as the inner contour. Then, reverse the order of the contour points of the inner contour according to the principle of reverse for the outer contour and forward for the inner contour.

[0134] 6. For each multi-connected region containing an inner contour, starting from the inner contour with the smallest y-coordinate in its corresponding set, find four key nodes, and divide the corresponding region according to the four key nodes to obtain a simply connected region that does not contain an inner contour.

[0135] If a multi-connected region contains multiple inner contours, the order of segmentation for these inner contours is as follows: first, segment out the inner contour containing the node with the smallest x-coordinate among the nodes with the smallest y-coordinates, and then segment out all the inner contours within the multi-connected region in this order.

[0136] like Figure 6 As shown, specifically, taking any unsegmented multi-connected region containing an inner contour as the current region, and its corresponding set as the current set, starting from the inner contour with the smallest y-coordinate in the current set, four key points are found, and the current region is segmented based on the key points as follows:

[0137] 6.1. Take the node with the smallest x-coordinate among the nodes with the smallest y-coordinate in the current set as the starting point, and traverse according to the order of the contour points. Take the first node with a y-coordinate different from the starting point as the first key point.

[0138] 6.2. Traverse from key point one in the positive direction of the horizontal axis, and take the first contour point on the inner contour of the current region as key point two.

[0139] 6.3. The key point is traversed in the negative direction of the horizontal coordinate until a contour point on the outer contour of the current region is encountered. If the adjacent contour point in the negative direction of the vertical coordinate of the contour point is also located on the outer contour, then the contour point is regarded as the third key point.

[0140] 6.4. Traverse the second key point in the positive direction of the horizontal coordinate until a contour point on the outer contour of the current region is encountered. The adjacent contour point in the negative direction of the vertical coordinate of this contour point is also located on the outer contour. This contour point is taken as the fourth key point.

[0141] 6.5 Connect key points one and three, key points two and four, the adjacent contour points of key point four in the negative direction of the vertical coordinate and the adjacent contour points of key point two in the negative direction of the vertical coordinate, the adjacent contour points of key point three in the negative direction of the vertical coordinate and the adjacent contour points of key point one in the negative direction of the vertical coordinate to form multiple new contour regions.

[0142] 6.6 If the new contour region formed in step 6.5 still contains the inner contour, repeat steps 6.1 to 6.5 until the new contour region no longer contains the inner contour.

[0143] 7. Split each simply connected region until using a zigzag path on each simply connected region will not result in a tool lift.

[0144] like Figure 7 and 8 As shown, the specific process of segmenting any unsegmented simply connected region as the current region until using a zigzag path will not result in a tool lifting error is as follows:

[0145] 7.1 Traverse the contour points of the current region in the order of the contour points until a contour point is found that satisfies the following conditions: the previous contour point of the contour point is located on the positive (negative) side of the vertical coordinate of the contour point, and the next contour point is located on the negative (positive) side of the horizontal coordinate of the contour point. Then, the contour point is regarded as the first key point.

[0146] 7.2. Search for the first key point in the negative (positive) direction of the horizontal axis according to the order of the contour points until a contour point appears. If the next contour point is located on the side of the positive (negative) direction of the vertical axis of the contour point, then let the contour point be the second key point.

[0147] 7.3 The second key point traverses in the negative (positive) direction of the horizontal coordinate until it encounters the first contour point of the current region, and uses that contour point as the third key point;

[0148] 7.4. The first key point is to traverse in the positive (negative) direction of the horizontal axis until the first contour point of the current region is encountered, and then the contour point is used as the fourth key point.

[0149] 7.5 Connect the first key point and the fourth key point, the second key point and the third key point, the adjacent contour points in the positive (negative) direction of the first key point's ordinate with the adjacent contour points in the positive (negative) direction of the fourth key point's ordinate, and the adjacent contour points in the positive (negative) direction of the third key point's ordinate with the adjacent contour points in the positive (negative) direction of the second key point's ordinate, and form new contours to complete the segmentation of the simply connected region.

[0150] 8. Generate zigzag paths in each segmented region, connect the first and last zigzag paths of each region to form the tool lifting path, and generate machining G-code.

[0151] For each region, the node with the smallest x-coordinate among the nodes with the smallest y-coordinate is taken as the starting point, and the zigzag path is obtained by stacking the nodes row by row along the y-coordinate direction.

[0152] Typical application example:

[0153] The path planning method for partitioning long carbon fiber composite freeform surfaces provided in the above embodiments is used to process, for example... Figure 9 Path planning is performed on the surface to be processed, as shown. (Example:) Figure 9The T-spline surface model shown is 50mm × 40mm × 15mm in size and is made of biaxial carbon fiber composite material. The machining residual height is limited to 0.01mm. The number of single nodes in the s and t directions of the parameter space is set to 500. The tool axis vector of each node is determined at a tool tilt angle of 15°. Figure 9 The small red cone is shown in the image. A 6mm double-edged ball end mill was used, with the five-axis machine tool spindle speed set to 12000rpm and the tool feed rate to 2000mm / min; the division threshold was set to 30°.

[0154] like Figure 10 As shown, multiple regions of the model (parameter space) are obtained, and the tool axis vectors at the boundaries of different regions change significantly.

[0155] Figure 11 The results of the partitioned processing path planning are shown, and zigzag paths are generated within each partition (within each region).

[0156] like Figure 12 As shown, the machining G-code was imported into Vericut software for simulation machining, and the simulation results showed that there were no major defects on the surface.

[0157] The JDGR300 five-axis high-speed machining center was used to perform both non-zonal machining (conventional machining path) and zone machining (machining path obtained through the above embodiments) on the carbon fiber composite plate. Figure 13 As shown, the non-zoned machined surface has obvious tool marks, resulting in low machining quality, and the machining time is 16 minutes and 34 seconds; Figure 14 As shown, the surface quality of the partitioned machining is high, with no obvious tool marks, and the machining time is 12 minutes and 40 seconds. Compared with non-partitioned machining, the partitioned machining time is reduced by 23.5%, demonstrating the algorithmic advantage of the path planning method in the above embodiments.

[0158] It will be understood by those skilled in the art that the above descriptions are merely preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. All modifications and equivalent substitutions made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A path planning method for partitioning freeform surfaces of long carbon fiber composite materials, characterized in that, Includes the following steps: (1) Obtain the two-dimensional parameter space of the surface to be processed and the tool axis vector of each node in the parameter space, and set the segmentation threshold at the same time; (2) Divide the parameter space into multiple regions according to the tool axis vector and the segmentation threshold of the node, and number the different regions and their nodes so that the regions and all nodes within them have the same number. (3) Establish multiple sets that correspond one-to-one with multiple regions, determine the contour points of each region, and store them into their respective sets; (4) Rearrange the contour points of each region and update the corresponding set. The rearranged contour points form the contour. (5) For each region, take the contour point with the smallest ordinate in its corresponding set as the outer contour and the rest as the inner contour. Then, according to the principle of reverse for the outer contour and forward for the inner contour, reverse the order of the contour points of the inner contour. (6) For each multi-connected region containing an inner contour, starting from the inner contour with the smallest ordinate in its corresponding set, find four key nodes, and divide the corresponding region according to the four key nodes to obtain a single-connected region that does not contain an inner contour. (7) Split each simply connected region until each simply connected region can be used with a zigzag path without causing a lift-up; (8) Generate zigzag paths in each segmented region, connect the first and last zigzag paths of each region as the lifting path, and generate machining G code.

2. The path planning method for partitioning the freeform surface of long carbon fiber composite materials according to claim 1, characterized in that, The specific operation process of step (2) is as follows: (2.1) Using the parameter space as the current region, take the node with the smallest x-coordinate among the nodes with the smallest y-coordinate as the starting node and number them, and use the starting node as the current node. (2.2) Perform a depth traversal of the current node in the four directions of the two coordinate axes, taking any untraversed direction as the current direction, calculate the angle between the current node and the tool axis vector of the next node in the current direction, and determine the magnitude of this angle relative to the segmentation threshold: If the included angle is less than the segmentation threshold, then mark the next node with the same number as the current node, and use the next node as the current node, repeating step (2.2). If the included angle is greater than the segmentation threshold, stop traversing, return to the current node, select other untraversed directions for traversal, and continue traversing until all four directions have been traversed. (2.3) Repeat step (2.2) until there are no more nodes in the current region whose angle between the cutter axis vector and the current node's cutter axis vector is less than the segmentation threshold, thus completing the division of a region; (2.4) Take the parameter space of the region divided in step (2.3) as the current region, and repeat steps (2.1) to (2.3) until all nodes are traversed and the region division of the parameter space is completed; during this period, each time step (2.1) is repeated, the number of the corresponding starting node is incremented by one.

3. The path planning method for partitioning the freeform surface of long carbon fiber composite materials according to claim 1, characterized in that, In step (3), the method for determining the contour points of any region is as follows: (3.1) Take any region as the current region, and take the node with the smallest x-coordinate among the nodes with the smallest y-coordinate in the current region as the input, and take it as the current node; (3.2) Perform a depth-first traversal of the current node in the four directions of the two coordinate axes. Taking any untraversed direction as the current direction, determine whether the next node of the current node in the current direction is located in the current region: If not, stop traversing in the current direction, return to the current node, and traverse the other untraversed directions; If so, then determine whether the next node of the current node is a contour point: If not, stop traversing in the current direction, return to the current node, and traverse the other untraversed directions; If so, store the next node in the set corresponding to the current region, and repeat step (3.2) with the next node as the current node.

4. The path planning method for partitioning the freeform surface of long carbon fiber composite materials according to claim 3, characterized in that, By determining whether the current node and its next node have the same number, we can determine whether the next node is located within the current region. The method for determining whether a point within the current region is a contour point is as follows: For the current node, if there is a node that is not in the current region among its eight adjacent nodes in the positive and negative directions that are parallel to the two coordinate axes and at a 45° angle to the two coordinate axes, then the current node is a contour point; otherwise, the current node is not a contour point.

5. The path planning method for partitioning the freeform surface of long carbon fiber composite materials according to claim 1, characterized in that, In step (4), the specific process of rearranging the contour points of each region is as follows: (4.1) Take any unrearranged region of contour points as the current region, take the contour point with the smallest abscissa among the nodes with the smallest ordinate in the current region as the contour starting point, determine the output direction of the contour starting point and use it as the input direction of the next contour point of the contour starting point in the output direction. (4.2) Take the next contour point as the current contour point, and determine the output direction of the current contour point according to the input direction of the current contour point and the number of its adjacent contour points, and obtain the input direction of the next contour point of the current contour point in the output direction. (4.3) Repeat step (4.2) until all contour points in the current area have been processed; (4.4) Repeat steps (4.1) to (4.3) until all regions have completed the rearrangement of outline points.

6. The path planning method for partitioning the freeform surface of long carbon fiber composite materials according to claim 5, characterized in that, The output direction of the contour starting point is determined as follows: First, search from the starting point of the contour in the positive direction of the horizontal coordinate. If a contour point exists in the current area, the positive direction of the horizontal coordinate is used as the output direction of the starting point of the contour; if it does not exist, the positive direction of the vertical coordinate is used as the output direction of the starting point of the contour.

7. The path planning method for partitioning the freeform surface of long carbon fiber composite materials according to claim 5, characterized in that, The method for determining the output direction of the current contour point based on its input direction and the number of its adjacent contour points is as follows: The number of contour points adjacent to the current contour point is divided into four cases: 1, 2, 3, and 4. The corresponding current contour points are designated as one-way points, two-way points, three-way points, and four-way points, respectively. The output direction of the current contour point under different cases is as follows: The output direction of a point is opposite to its input direction. The output direction of a bidirectional point is the same as its input direction. For a three-way point, if the adjacent node in the direction of clockwise rotation of 90° from its input direction is the contour point of the current region, then the direction of clockwise rotation of 90° from the input direction of the three-way point is taken as its output direction; otherwise, its output direction is the same as its input direction. The output direction of a four-way point is 90° clockwise from its input direction.

8. The path planning method for partitioning the freeform surface of long carbon fiber composite materials according to claim 1, characterized in that, In step (6), any unsegmented multi-connected region containing an inner contour is taken as the current region, and its corresponding set is taken as the current set. Starting from the inner contour with the smallest ordinate in the current set, four key points are found, and the current region is segmented based on the key points as follows: (6.1) Take the node with the smallest x-coordinate among the nodes with the smallest y-coordinate of the inner contour in the current set as the starting point, and traverse according to the order of the contour points. Take the first node with a y-coordinate different from the starting point as the first key point. (6.2) Traverse from key point one in the positive direction of the horizontal coordinate, and take the first contour point on the inner contour of the current region as key point two; (6.3) The key point is traversed in the negative direction of the horizontal coordinate until a contour point on the outer contour of the current region is encountered. If the adjacent contour point in the negative direction of the vertical coordinate of the contour point is also located on the outer contour, then the contour point is regarded as the third key point. (6.4) Traverse the second key point in the positive direction of the horizontal coordinate until a contour point on the outer contour of the current region is encountered. The adjacent contour point in the negative direction of the vertical coordinate of the contour point is also located on the outer contour. This contour point is taken as the fourth key point. (6.5) Connect key points one and three, key points two and four, the adjacent contour points of key point four in the negative direction of the vertical coordinate and the adjacent contour points of key point two in the negative direction of the vertical coordinate, the adjacent contour points of key point three in the negative direction of the vertical coordinate and the adjacent contour points of key point one in the negative direction of the vertical coordinate to form multiple new contour areas. (6.6) If the new contour region formed in step (6.5) still contains the inner contour, repeat steps (6.1) to (6.5) until the new contour region no longer contains the inner contour.

9. The path planning method for partitioning the freeform surface of long carbon fiber composite materials according to claim 1, characterized in that, In step (7), the specific process of segmenting any unsegmented simply connected region as the current region until using a zigzag path will not result in a tool lifting operation is as follows: (7.1) Traverse the contour points of the current region in the order of the contour points until a contour point is found that satisfies the following condition: the previous contour point of the contour point is located on the positive side of the vertical coordinate of the contour point, and the next contour point is located on the negative side of the horizontal coordinate of the contour point. Then, the contour point is taken as the first key point. (7.2) The first key point is searched in the negative direction of the horizontal axis according to the order of the contour points until a contour point appears. The next contour point is located on the side of the positive direction of the vertical axis of the contour point. Then the contour point is called the second key point. (7.3) The second key point is traversed in the negative direction of the horizontal coordinate until the first contour point of the current area is encountered, and the contour point is used as the third key point; (7.4) The first key point is to traverse in the positive direction of the horizontal axis until the first contour point of the current area is encountered, and the contour point is used as the fourth key point; (7.5) Connect the first key point and the fourth key point, the second key point and the third key point, the adjacent contour points in the positive direction of the ordinate of the first key point and the adjacent contour points in the positive direction of the ordinate of the fourth key point, the adjacent contour points in the positive direction of the ordinate of the third key point and the adjacent contour points in the positive direction of the ordinate of the second key point, and form new contours to complete the segmentation of the single connected region. Alternatively, (7.1) traverse the contour points of the current region in the order of the contour points until a contour point is found that satisfies the following condition: the previous contour point of the contour point is located on the negative side of the vertical coordinate of the contour point, and the next contour point is located on the positive side of the horizontal coordinate of the contour point. Then, take the contour point as the first key point. (7.2) The first key point is searched in the positive direction of the horizontal axis according to the order of the contour points until a contour point appears. The next contour point is located on the negative side of the vertical axis of the contour point. Then the contour point is called the second key point. (7.3) The second key point is traversed in the positive direction of the horizontal coordinate until the first contour point of the current area is encountered, and the contour point is used as the third key point; (7.4) The first key point is traversed in the negative direction of the horizontal coordinate until the first contour point of the current area is encountered, and the contour point is taken as the fourth key point; (7.5) Connect the first key point and the fourth key point, the second key point and the third key point, the adjacent contour points in the negative direction of the ordinate of the first key point and the adjacent contour points in the negative direction of the ordinate of the fourth key point, and the adjacent contour points in the negative direction of the ordinate of the third key point and the adjacent contour points in the negative direction of the ordinate of the second key point to form new contours and complete the segmentation of the single connected region.

10. The path planning method for partitioning the freeform surface of long carbon fiber composite materials according to claim 1, characterized in that, In step (8), for each region, the node with the smallest horizontal coordinate among the nodes with the smallest vertical coordinate is taken as the starting point, and the zigzag path is obtained by stacking the nodes row by row along the vertical coordinate direction.

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