CN-116811231-B - Five-axis linkage material increasing and decreasing mixed machining sequence planning method

CN116811231BCN 116811231 BCN116811231 BCN 116811231BCN-116811231-B

Abstract

The invention discloses a planning method of a five-axis linkage material increasing and decreasing mixed machining sequence, which comprises the steps of firstly calculating the centroid of a slice section based on equal-thickness layered slice sections of a part to obtain the centroid of a column structure part, then establishing a tool accessibility model in the material increasing and decreasing mixed machining process according to the problem of tool collision interference in the material increasing and decreasing mixed machining process, providing a bounding box accelerating structure, accelerating the model solving process, coarsely decomposing the part by utilizing the accessibility model and the accelerating structure, establishing the material increasing and decreasing mixed machining sequence, finally adjusting the included angle between a five-axis linkage printing platform and a tool, and optimizing to obtain a final machining sequence. The method establishes the tool accessibility model in the process of mixed machining of the increased and decreased materials, ensures that collision interference of the tools does not occur in the machining process, provides the bounding box accelerating structure, accelerates the accessibility model solving process, obtains the final mixed machining sequence of the increased and decreased materials by adjusting the angle between the five-axis linkage machining platform and the machining tool, and improves the machining efficiency.

Inventors

LU CONG
HU KAIXIANG
YANG JING
YU YI
YAN ZONGMING

Assignees

电子科技大学

Dates

Publication Date: 20260505
Application Date: 20230619

Claims (4)

1. A planning method for a five-axis linkage material increasing and decreasing mixed machining sequence comprises the following specific steps: s1, calculating a section centroid of a section based on equal-thickness layering section of a part to obtain a centroid of a column structure part; S2, aiming at the problem of cutter collision interference in the process of material increasing and decreasing mixing processing, a cutter accessibility model in the process of material increasing and decreasing mixing processing is established; s21, simplifying a cutter into rays based on the centroid of the section of the part slice, and establishing a simplified cutter mathematical model; the simplified tool needs to meet the following three conditions: (1) Determining a cutter contact point and a cutter direction; Setting the radius of the ball end milling cutter head as R, wherein the cutter contact point is a cutting point, and taking the circle center of an circumscribed circle with the radius of the cutting point as R as a starting point of a simplified rear cutter, namely a ray starting point, and simplifying the direction of the rear cutter, namely the ray direction; For the print head, the contact point can be regarded as the starting point of the simplified back cutter, i.e. the starting point of the radiation, while the direction of the simplified back cutter, i.e. the direction of the radiation; (2) A cutter continuity problem; Calculating continuity on the contour of the part for a printing head and a cutting tool bit in the process of increasing and decreasing material mixing processing, taking any point p on the contour of the surface of the part, and calculating the accessibility of a tool for each point in the field with the radius sigma around the point so as to meet the requirement of the continuity of the tool; The layering characteristics of 3D printing are that the layering thickness is set as a step length to discrete the vertical dimension, and the cutter accessibility is calculated for each point after the discrete, so that the cutter continuity in the vertical dimension can be met; the step length setting of any point on the contour is required to be smaller than the distance of the cutter moving by one cutter position, and the maximum value is the diameter D of the cutter head; (3) The feasible range of the cutter under the support-free condition; realize the unsupported printing by using the five-axis linkage processing platform, when printing the part with hanging structure, the printing direction of the front layer is The external normal vector of the triangular surface patch on the side face of the hanging structure is The conditions satisfied without using a support structure are as follows: (1); Wherein, the The value of (2) is Or (b) Selecting different processing environments for different parts; if the included angle between the printing direction and the normal vector of the triangular surface patch on the side surface of the hanging structure is larger than The processing is stopped due to the collapse of the suspended structure, so that the feasible range of the cutter under the support-free condition is the plane direction of the printed layer of the suspended structure The positive axis direction is The sum of the range of angles plus the range below the plane of the print layer; the general equation after tool simplification, i.e. simplified tool mathematical model, is expressed as follows: (2); Wherein, the Representing the origin of the ray, Represents a direction vector, an , Representing the ray emission distance, regarding the simplified ray as an infinitely long; S22, based on the obtained simplified tool mathematical model, a tool collision interference algorithm is established; traversing all triangular patches of the STL model and intersecting with the simplified tool mathematical model, if an intersection point exists, generating tool collision interference, otherwise, generating no collision, wherein the intersecting process is specifically as follows: Calculating whether the simplified tool mathematical model equation has an intersection point with the plane of the triangular patch, and setting three vertexes of the triangle as respectively 、 And The equation for the plane of the triangular patch is: (3); Wherein M, N, O, P represent plane equation parameters, and the normal vector of the plane of the triangular patch is All three vertices of the triangle are in the plane, and any point can be brought in: (4); And (3) bringing the simplified tool mathematical model equation into a plane equation, and obtaining: (5); Wherein, the Representing the distance from the starting point of the cutter to the intersection point of the triangle; If it is It is stated that the triangles will not intersect after the tool, if Then the triangle is intersected before the cutter, and the intersection point of the cutter and the plane of the triangle is obtained ; Then judge Whether or not the triangle is in the triangle, respectively connecting three vertexes and intersection points of the triangle Connected to obtain three vectors 、 And And respectively calculating the cross multiplication of the vectors formed by the three vectors and three sides of the triangle: (6); if three directions of cross multiplication and normal vector of triangle If the directions are consistent, the intersection point is in the triangle, and if the directions are inconsistent, the intersection point is not in the triangle; S3, providing a bounding box accelerating structure to accelerate a model solving process; s4, coarse decomposition is carried out on the parts by utilizing the reachability model and the accelerating structure, a mixed machining sequence of increasing and decreasing materials is established, finally, the included angle between the five-axis linkage printing platform and the cutter is adjusted, and the final machining sequence is obtained through optimization.
2. The method for planning a mixed machining sequence of five-axis linkage increase and decrease materials according to claim 1, wherein the step S1 is specifically as follows: obtaining the whole part slicing result by adopting equal-thickness layering, and obtaining the centroid of the polygon of the current slicing section for each layer of part slicing section; The calculation of the section centroid of the slice is specifically as follows: The section of the slice is set to contain Polygon with multiple vertices, composed of The triangles are combined, which Triangle by triangle The two remaining points are respectively And And (2) and ; Set the first The gravity center of each triangle is , The two remaining points are respectively And The gravity center is obtained by a gravity center formula The expression is as follows: (7); center of gravity of slice cross-section polygon And the components thereof The relational expression of the centers of gravity of the triangles is as follows: (8); Wherein, the Represent the first The area of the triangle; Is provided with Multiple vertices Polygonal centroid of slice section of (a) is Area is The polygon centroid calculation expression is as follows: (9); the section profile of each slice of the part is a combined polygon, and a centroid point is obtained for the section profile of each slice , Representing the current contour level, for having The parts of the layers are A centroid point; and finally, sequentially connecting all cross section centroids to obtain the centroids of the column structural parts.
3. The method for planning a mixed machining sequence of five-axis linkage increase and decrease materials according to claim 1, wherein the step S3 is specifically as follows: s31, constructing a bounding box based on triangular patch coordinates, recursively constructing a tree by subdividing the bounding box, and constructing a tree bounding box structure; (1) Ordering all triangular patches in the model according to the gravity center positions of the triangular patches, wherein the ordering method can be respectively selected according to the difference of geometric features of the model Ordering according to coordinate size Ordered or otherwise in accordance with coordinate size Sorting the coordinate sizes; (2) Creating nodes of the tree bounding box, wherein the nodes comprise outline information of the bounding box, leaf node information and indexes of left and right subtrees; (3) Determining the number of triangular patches according to the triangular patch data obtained in the step (1), and setting the number as Initial left subscript For 0, constructing a triangular patch array, and setting each bounding box to least contain the triangular patch as ; (4) Constructing a bounding box of a current tree node, wherein the left index of the current tree node is as follows The right subscript is ; (5) Traversing subscripts in a triangular patch array Is provided with a pair of triangular face sheets, calculate all triangular patches Constructing the current bounding box outline by the maximum value of the coordinates; (6) Whether the number of triangular patches in the bounding box is smaller than If yes, directly constructing a current node bounding box and returning to the current leaf node, otherwise, continuing recursively constructing a tree; (7) Calculated according to step (5) Selecting the longest axis, and sequencing the barycentric coordinates of the triangular patches in the bounding box according to the coordinate values of the axes; (8) Triangular dough sheet array midpoint Dividing all triangular patches into two parts, left half The subscript is not changed and the code, The subscript is changed to Right half The subscript is changed to , Returning to the step (4) for recursively building a tree with the subscript unchanged, wherein the left subtree uses a left half triangular patch and the subscript, and the right subtree uses a right half triangular patch and the subscript; continuously repeating the steps (1) - (8) to finish the establishment of the tree-shaped bounding box; S32, intersecting the simplified mathematical model of the cutter with the tree-shaped bounding box structure; an AABB bounding box having three opposite planes, respectively The shaft is perpendicular to three groups of planes, three pairs of planes are intersected respectively, the penetrating point and the penetrating point of each group of planes are calculated, whether the cutter is intersected with the bounding box or not is judged according to the coordinates of the penetrating point and the penetrating point, if so, the cutter is intersected with a triangular surface patch in the bounding box, and the intersection point of the cutter and the STL model is obtained; calculating the distance between the two intersecting points of the cutter and a group of opposite surfaces and the starting point according to the cutter simplification equation Let the coordinates of the lower left point of the bounding box be The coordinates of the upper right point are The direction of the cutter is Then the left lower corner coordinate of the bounding box Divided by tool direction Obtaining a three-dimensional vector Upper right coordinates of bounding box Divided by tool direction Obtaining a three-dimensional vector Taking out The maximum of three coordinates in the vector is recorded as , The minimum values of three coordinates in the vector are recorded as Judging whether or not there is If (if) The cutter collides with the bounding box to interfere, otherwise the cutter does not collide with the bounding box to interfere; Wherein, the Indicating that the tool is perpendicular to the bounding box Penetration point of the axial surface The axis of the rotation is set to be at the same position, Indicating that the tool is perpendicular to the bounding box Penetration point of the axial surface The axis of the rotation is set to be at the same position, Indicating that the tool is perpendicular to the bounding box Penetration point of the axial surface Axis coordinates, relative vector Corresponding to the three opposite point-of-penetration coordinates, respectively.
4. The method for planning a mixed machining sequence of five-axis linkage increase and decrease materials according to claim 1, wherein the step S4 is specifically as follows: S41, gradually calculating the tool accessibility from the bottom contour upwards by using a simplified printing head equation and a tool accessibility model, if collision interference occurs, decomposing the part from the current tool starting point and the collision interference point, and if collision interference does not occur, moving the tool upwards by one layer until the part is decomposed, and obtaining a processing sequence only considering the printing head collision; s42, adjusting the included angle between the five-axis linkage processing platform and the cutter when the accessibility of each layer of cutter is calculated by utilizing the characteristics of the five-axis linkage processing platform and a greedy algorithm, so as to obtain the highest interference point when collision interference occurs, reduce the number of times of cutter changing, and obtain the optimized mixed processing sequence of the increased and decreased materials.

Description

Five-axis linkage material increasing and decreasing mixed machining sequence planning method Technical Field The invention belongs to the technical field of 3D printing data processing, and particularly relates to a five-axis linkage material increasing and decreasing mixed processing sequence planning method. Background 3D printing (also known as additive manufacturing) refers to a manufacturing technique that builds up layers of material (e.g., plastic, liquid, or powder particles) build up from CAD models or digital 3D models by deposition, joining, and curing of the material under control of a computer. The existing 3D printing has great limitation in the aspects of precision and surface quality control of part forming, direct high-precision printing of parts is difficult to realize, and cutting machining based on material reduction manufacturing is good in the aspects of precision and quality control of the parts. Therefore, the additive manufacturing and the cutting processing are combined to form a mixed processing technology of increasing and decreasing materials, the advantages of short period, high material utilization rate and the like of the additive manufacturing can be brought into play, the advantages of high quality and high precision of the surface of the formed part by the cutting processing can be combined, and the high-efficiency, high-precision and high-performance formed part manufacturing can be realized. For complex structural components, such as engine structural components of impellers, blisks and the like, the appearance is complex, the requirements on performance and precision are high, the existing numerical control cutting is difficult to process, the problem of collision and interference of cutters easily occurs in the cutting process due to the complex appearance of the parts, the high precision of the parts is difficult to ensure, and the structural design of the parts is required to be given way due to the existence of the problem of collision and interference of the cutters, so that the performance requirements of the parts cannot be met. The problem of tool collision interference during cutting is also frequent for columnar structures, elongated and curved structures, and structures containing cavities. The mixed manufacturing of the increase and decrease materials provides a direction for high-precision processing of complex structural members, the problems of cutter collision interference can be solved by the mixed additive manufacturing and the subtractive manufacturing, the printed parts of the parts are cut and processed in the additive manufacturing process before the cutters possibly collide and interfere, the collision between the cutters and the parts can be avoided, the parts with high precision can be obtained, and the risks brought by the cutter collision interference problem can be avoided. Disclosure of Invention In order to solve the technical problems, the invention provides a planning method for a five-axis linkage material increasing and decreasing mixed machining sequence, which can calculate the collision interference condition of a cutter in real time in the material increasing and decreasing process, ensure that the material increasing and decreasing process can be smoothly carried out, and optimize the material increasing and decreasing mixed machining sequence under the condition that the collision interference of the cutter cannot occur is ensured. The technical scheme adopted by the invention is that a planning method for a five-axis linkage increase-decrease material mixed processing sequence comprises the following specific steps: s1, calculating a section centroid of a section based on equal-thickness layering section of a part to obtain a centroid of a column structure part; S2, aiming at the problem of cutter collision interference in the process of material increasing and decreasing mixing processing, a cutter accessibility model in the process of material increasing and decreasing mixing processing is established; S3, providing a bounding box accelerating structure to accelerate a model solving process; s4, coarse decomposition is carried out on the parts by utilizing the reachability model and the accelerating structure, a mixed machining sequence of increasing and decreasing materials is established, finally, the included angle between the five-axis linkage printing platform and the cutter is adjusted, and the final machining sequence is obtained through optimization. Further, the step S1 specifically includes the following steps: And obtaining the whole part slicing result by adopting equal-thickness layering, and obtaining the centroid of the polygon of the current slicing section for each layer of part slicing section. The calculation of the section centroid of the slice is specifically as follows: The section of the slice is set to be a polygon with n vertexes, the polygon is formed by combining n-2 triangles, the n-2 triangles take