A method for solving the tool axis vector in bladed disk machining based on hierarchical non-interference feasible region.

Abstract

This invention belongs to the field of multi-axis CNC machining, specifically relating to a method for solving the tool axis vector in bladed disk machining based on a hierarchical non-interference feasible region, and a corresponding tool axis vector optimization device. The method first divides the tool axis space into partitions based on the forward tilt angle and side tilt angle within a newly constructed tool-touch coordinate system, and then discretizes the tool axis vector hierarchically. Next, within different intervals, collision rule detection and judgment are performed on the sequence of interference points to filter out the non-interference feasible region of the tool axis vector. Then, a solution model based on minimizing the change in tool axis vector angle is established to solve for the tool axis vector in the blade machining path, and the tool axis path with the minimum weight is calculated. Finally, a moving weighted smoothing model is constructed to obtain the smooth tool axis vector in the machining path. This invention solves the problems of collision interference and overcutting interference between the tool and the workpiece surface in five-axis machining, and improves the computational efficiency of non-interference tool axis vectors.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of multi-axis numerical control machining, and particularly relates to a blisk machining tool axis vector solving method based on a hierarchical non-interference feasible region and a corresponding tool axis vector optimization device. BACKGROUND

[0002] Modern national defense, energy and other civil fields increasingly widely use blisk parts, such as aero-engines, large ships, etc. High-efficiency and precision numerical control machining technology for such parts has become one of the important manifestations of the core competitiveness of advanced manufacturing enterprises.

[0003] With the development of numerical control systems, advanced five-axis numerical control machine tools can realize the swing of the tool axis at any position in the three-dimensional space within the working stroke of the machine tool. Therefore, by reasonably selecting the tool axis, most multi-axis machining tasks can be met. However, if the tool axis vector is not selected properly, it will cause the tool axis vector to change dramatically during cutting, resulting in a large angular velocity and angular acceleration of the rotating shaft of the machine tool, and even the "reverse rotation" of the rotating shaft. Many engineering practices show that these dramatic changes will seriously affect the quality of the machined surface. For example, poor quality machined surfaces such as "fish scale-like" pits are produced, thereby greatly limiting the application of high-precision multi-axis numerical control machine tools. These contradictions are particularly pronounced in the process of cutting overall structural parts.

[0004] To meet the performance requirements of key parts, the part surface is complex and the machining precision is extremely high. With five-axis numerical control machine tools becoming one of the important machining means for solving complex curved surface parts, the increase of the rotating degree of freedom of the five-axis numerical control machine tool increases the flexibility of curved surface machining, but also increases the complexity of interference problems due to space limitations, such as collision interference and overcut interference between the tool and the part surface, and collision interference between the machine tool and the part surface. If these interference problems cannot be effectively solved, they will at least affect the machining quality of the curved surface part, and at most cause major production accidents. The machining interference problem of the five-axis numerical control machine tool has become an important problem in the machining of complex curved surface parts. The traditional non-interference tool axis vector feasible region planning strategy discretizes the tool axis vector within the hemisphere. Although this approach can ensure the smoothness of the tool axis vector, it has low solving efficiency in actual operation. In the technical literature "Research on Tool Axis Vector Optimization Based on Directed Graph", Liu Hongjun et al. established a tool contact coordinate system using tool contact point information and divided the tool axis vector under large angles, which took 546s to test 120 tool contact points. Therefore, it is extremely important to improve the calculation efficiency of the tool axis vector under the premise of ensuring machining accuracy. SUMMARY

[0005] In order to solve the collision interference and overcut interference between the tool and the part surface in the five-axis machining process, and improve the calculation efficiency of the tool axis vector without interference, the present application provides a blisk machining tool axis vector solving method and device based on hierarchical interference-free feasible region.

[0006] The present application adopts the following technical solutions:

[0007] A blisk machining tool axis vector solving method based on hierarchical interference-free feasible region, comprising the following steps:

[0008] S1: Based on the geometric characteristics of the blisk workpiece, the tangent plane of the tool contact point is represented as the YOZ plane, and the corresponding tool contact coordinate system is established.

[0009] S2: In the tool contact coordinate system, the movable space of the tool axis vector is divided, the rake angle θ is divided into p dimensions, and the roll angle β is divided into q dimensions in four consecutive hierarchical intervals under a given rake angle, and then the tool axis vector T corresponding to each interval is determined according to the division results of each rake angle θ and roll angle β.

[0010] S3: The projection section of the tool axis is the tool projection receiving section, and the influence of the tool end face on the projection rectangle is considered, and the tool coordinate system is established as follows with the direction of the tool axis vector T as the Z-axis direction;

[0011]

[0012] In the above formula, W1 is a unit vector representing the X-axis direction of the tool coordinate system, W2 is a unit vector representing the Y-axis direction of the tool coordinate system; K W represents the unit vector of the Z-axis direction in the tool coordinate system.

[0013] S4: Establish the envelope box of the tool represented by each tool axis vector, and select all the sets of detection points Q located in the envelope box from the detection area.

[0014] S5: Collision detection and judgment are performed on all tool axis vectors in the hierarchical movable interval; the roll angle in the given rake angle value range is traversed, the interference is determined, and the roll angle corresponding to the non-interference tool axis vector is recorded; and then the tool axis vector feasible region under the condition of non-interference of the tool contact point is obtained.

[0015] S6: The change amount of the tool axis vector between two adjacent tool contact points is taken as the optimization target, and a smoothing optimization model of the overall tool axis vector is established.

[0016] S7: The change amount of the adjacent tool axis vector is taken as the weight, and the weighted directed graph of the tool axis vector is established combined with the sequence of the tool contact point in machining.

[0017] S8: Connectivity detection is performed on the initial tool axis vector and the tool axis vector at the end point of the tool contact point trajectory by using the Dijkstra algorithm, and the shortest machining path that satisfies the optimal fairness is solved.

[0018] S9: The tool axis vector in the machining path is subjected to moving window weighted smoothing processing, and the smoothed tool axis vector in the entire machining path is finally obtained.

[0019] As a further improvement of the application, in step S1, the creation process of the tool contact coordinate system is as follows:

[0020] S11: Define the position coordinates of the tool contact point P, the normal vector of the tool contact point P on the curved surface is k, and the radius of the ball nose tool is R, then the position of the tool position point M in the workpiece coordinate system satisfies the following formula:

[0021] M=P+Rk.

[0022] S12: Project the tool contact point P onto the hub surface of the blade disc to obtain an auxiliary vector V.

[0023] S13: Project the vector V onto the tool contact tangent plane to obtain the vector Vz as the Z-axis direction of the tool contact coordinate system.

[0024] S14: Cross multiply Vz and the tool contact tangent vector to obtain the vector Vy as the Y-axis direction of the tool contact coordinate system.

[0025] S15: Cross multiply Vz and Vy to obtain Vx as the X-axis direction of the tool contact coordinate system.

[0026] As a further improvement of the application, in step S2, the expression of each tool axis vector T generated according to the divided movable interval is as follows:

[0027]

[0028] In the above formula, i e represents the unit vector of the X-axis direction of the tool contact coordinate system; j e represents the unit vector of the Y-axis direction of the tool contact coordinate system; k e represents the unit vector of the Z-axis direction of the tool contact coordinate system; i and j represent the dimension number of the divided rake angle θ and the inclination angle β, respectively; 0≤i≤p, 0≤j≤q; the value range of the inclination angle β is:

[0029] β∈[0,π / 6], (π / 6,π / 4], (π / 4,π / 3] and (π / 3,π / 2]; the value range of the rake angle θ is:

[0030] θ∈(-π / 2,π / 2).

[0031] As a further improvement of the present application, in step S4, the length and width of the envelope box are respectively 1.5 times the radius in the tool coordinate system, and the height is the length of the tool shank; the coordinates of the vertices of the envelope box are as follows:

[0032]

[0033] In the above formula, R T represents 1.5 times the radius of the ball head of the ball head milling cutter; L represents the length of the tool shank of the ball head milling cutter.

[0034] As a further improvement of the present application, in step S5, the collision detection process of the tool axis vector is as follows:

[0035] (1) Project the tool on the workpiece coordinate system X W O W Y W plane to obtain a rectangular region;

[0036] (2) Determine whether the detection point Q interferes with the tool, that is, determine whether the detection point Q is inside the tool, and let Q1 be the projection point of Q on the tool axis, and the coordinates of the projection point Q1 are:

[0037]

[0038] In the above formula, κ is the distance coefficient of point Q1 to tool position point M; MQ represents the vector from M point to Q point;

[0039] At this time, the vector QQ1 from point Q to point Q1 can be expressed as:

[0040] QQ1=QM+κT

[0041] In the above formula, QM represents the vector from Q point to M point;

[0042] (3) According to the vectors QQ1 and QM, the following judgment is made:

[0043] A: When κ>L or κ<-R, it means that the detection point Q is completely outside the tool model, and Q will not interfere with the tool.

[0044] B: When -R≤κ≤L, it means that the detection point is in the range that may interfere with the tool model;

[0045] b1: When -R≤κ≤0, calculate ||QM||, when ||QM||<R, the detection point is inside the tool ball head, Q interferes with the tool; otherwise, the detection point is not inside the tool ball head, Q does not interfere with the tool;

[0046]

[0047] ​b2: when 0≤κ≤L, calculate ||QQ1||, when ||QQ1||<R, the to-be-detected point is inside the tool bar, and the point Q interferes with the tool; otherwise, the to-be-detected point is not inside the tool bar, and Q does not interfere with the tool.

[0048] As a further improvement of the present application, in step S6, let the tool axis vector at the i-th tool contact point be V i , and the tool axis vector at the i+1-th tool contact point be V i+1 , then the tool axis vector variation between two adjacent tool contact points can be represented by the included angle θ between the tool axis vectors as follows:

[0049] θ(V i ,V i+1 )=arccos(V i ,V i+1 );

[0050] The sum s of the overall tool axis vector variation on the tool contact point sequence can be represented as:

[0051]

[0052] Taking the minimum tool axis vector variation along the tool feed direction as the optimization objective, the following smoothness optimization model is constructed:

[0053]

[0054] In the above formula, C is the set of nodes in the feasible region; θ max is the threshold value of the adjacent tool axis vector variation calculated according to the feed speed and the tool path step length.

[0055] As a further improvement of the present application, in step S7, the construction method of the weighted directed graph of the tool axis vector is as follows:

[0056] Assuming that each feasible tool axis vector is a vertex in the directed graph, and each vertex P i belongs to the set C(P i ) uniquely, then the vertices in two adjacent sets can be arbitrarily associated, and the connecting line between two vertices is called an arc; the variation θ(V i ,V i+1 ) of the adjacent tool axis vectors is set as the weight related to the arc; if θ(V i ,V i+1 ) exceeds the maximum variation threshold θ max of the tool axis vector at the adjacent tool contact point, then this arc is set as invalid and is removed from the directed graph, thereby establishing the weighted directed graph.

[0057] As a further improvement of the present application, in step S8, the optimization method of the shortest machining path is as follows:

[0058] After the directed graph is established, the connectivity of each tool axis vector of the initial tool axis vector and the end point of the tool contact point trajectory is detected, and each vertex is searched forward along the feed direction of the tool contact point trajectory, the minimum weight value of each vertex to the initial point is calculated and recorded, the weight value of the initial point to all feasible tool axis vectors at the second tool contact point is calculated and recorded, and then the forward search is sequentially performed until the end of the trajectory, finally, the weight values of each path at the end are compared to find the corresponding shortest machining path.

[0059] As a further improvement of the present application, the expression of the moving window weighted smoothing processing of the tool axis vector in the machining path is as follows:

[0060]

[0061] In the above formula, T' m represents the tool axis vector of the corrected window center, w represents the half width of the moving window, T m-i represents the data in the window, w i represents the weight coefficient, which is used for weighting the data in the window.

[0062] The present application also includes a tool axis vector optimization device, which comprises a memory, a processor and a computer program stored in the memory and running on the processor, and when the processor executes the computer program, the tool axis vector solving method based on the hierarchical interference-free feasible region as described above is realized, and the tool axis vector of the shortest machining path that can meet the collision-free, fairness and smoothness constraints in the blade machining process is generated.

[0063] The technical scheme provided by the present application has the following beneficial effects:

[0064] The present application analyzes the tool axis vector feasible region under the condition of single tool contact point interference-free, establishes a tool contact point interference-free tool axis vector feasible region solving method considering the fairness and correlation of adjacent tool axis vectors, establishes a solving model algorithm based on the minimum tool contact point tool axis vector angle as the optimization target, and realizes the efficient solving of the optimal tool axis vector under the condition of interference-free in the machining path through the Dijkstra algorithm. Furthermore, the collision interference and overcut interference problems between the tool and the part surface in the five-axis machining process are overcome, and the calculation efficiency of the interference-free tool axis vector is improved.

[0065] The tool axis vector calculated according to the method of the present application not only has higher solving efficiency, but also has smaller tool axis fluctuation, effectively inhibiting the tool chatter in the five-axis machining process. Therefore, it can be directly applied to the control system of the five-axis machine tool machining to improve the machining efficiency of the five-axis machine tool. BRIEF DESCRIPTION OF DRAWINGS

[0066] Figure 1The flow chart of solving the tool axis vector feasible region without interference of the blade machining based on hierarchical non-interference feasible region provided in Embodiment 1 of the present application.

[0067] Figure 2 The schematic diagram of implementing hierarchical retrieval of the tool axis vector in the test experiment.

[0068] Figure 3 The schematic diagram of generating the single-point partitioned tool axis vector feasible region without interference in the test experiment.

[0069] Figure 4 The schematic diagram of solving the optimal tool axis vector of the tool path based on the directed graph in the test experiment.

[0070] Figure 5 The schematic diagram of the principle of the moving weighted smoothing model used in the test experiment.

[0071] Figure 6 The visualized image of the optimal tool axis vector in the blade machining path of the blade of the blade disc obtained in the test experiment.

[0072] Figure 7 The comparison diagram of the tool axis vector variation rate of the blade machining tool path of the blade of the blade disc in the present application and the UG scheme in the test experiment. DETAILED DESCRIPTION

[0073] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0074] Embodiment 1

[0075] The present embodiment provides a blade machining tool axis vector solving method based on hierarchical non-interference feasible region. The method first studies and analyzes the tool axis vector feasible region under the condition of non-interference of a single tool contact point, realizes partitioning of the tool axis space in the newly constructed tool contact coordinate system, and discretizes the tool axis vector in stages. Then, the collision rule detection and judgment are performed on the interference point sequence in different interval ranges, and the tool axis vector feasible region without interference is screened out. Next, a solving model based on the minimum angle change of the tool axis vector is established as the optimization objective, the tool axis vector in the blade machining path is solved, and the tool axis path with the minimum weight is calculated by combining the Dijkstra algorithm. Finally, a moving weighted smoothing model is constructed, and the smoothing tool axis vector in the machining path is obtained by using the moving weighted smoothing model.

[0076] Specifically, the scheme provided in the present embodiment includes the following steps:

[0077] Based on the geometric characteristics of the blade disc workpiece, the tangent plane of the tool contact point is expressed as a YOZ plane, and a corresponding tool contact coordinate system is established.

[0078] In this embodiment, the position coordinates of the tool contact point P are defined, the tool contact normal vector is k, and the radius of the ball nose tool is R. The position of the tool position point M in the workpiece coordinate system satisfies the following formula:

[0079] M = P + Rk (1)

[0080] According to the tool motion trajectory equation C(u(t), v(t)) on the curved surface, any tool contact point P on the trajectory is established, and its tool contact coordinate system is established: the tool contact point P is projected onto the blade disc hub surface to obtain an auxiliary vector V. The vector V is projected onto the tool contact tangent plane to obtain the vector Vz as the Z-axis direction of the tool contact coordinate system. The cross product of Vz and the tool contact tangent vector is obtained as the Y-axis direction of the tool contact coordinate system. The cross product of VZ and Vy is obtained as the X-axis direction of the tool contact coordinate system.

[0081] According to the shape of the blade disc blade, the YOZ plane of the tool contact coordinate system in step two can be expressed as the tangent plane of the tool contact point, and the entire range of the rake angle of the tool that can rotate around the tool axis is divided. In this embodiment, the initial value range of the rake angle θ is: θ ∈ (-π / 2, π / 2), the rake angle is equally divided, and the division dimension is p, then each part of the rotation angle θ i can be expressed as:

[0082] θ i = -π / 2 + (iπ / p), (0 ≤ i ≤ p) (2)

[0083] Given the rake angle, the roll angle is further classified and divided. In this embodiment, the value range of the roll angle β is set to: β ∈ [0, π / 6], (π / 6, π / 4], (π / 4, π / 3] and (π / 3, π / 2], and the division dimension of the roll angle is q, which can effectively reduce the unnecessary tool axis vector calculation scale and improve the calculation efficiency. Each part of the roll angle β j can be expressed as:

[0084] β j = β1 + j(β n - β1) / q, (0 ≤ j ≤ q) (3)

[0085] Let the tool axis vector of the ball nose tool be T, then in the tool contact coordinate system, the actual tool axis vector corresponding to the roll angle β and the rake angle θ around the Z-axis at the tool contact point can be expressed as:

[0086] T = i e · cos θ sin β + j e · sin θ sin β + k e• cos β (4)

[0087] The tool coordinate system is established, the projection section of the tool axis is taken as the tool projection light receiving section, two base vectors of the section are taken, one is the tool axis vector T, and the other is the unit vector W1, a correction unit vector W2 is added considering the influence of the tool end face on the projection rectangle, wherein W1 and W2 are:

[0088]

[0089] The envelope box is established, and the range of the interference detection point corresponding to the tool axis vector of the tool contact point P is determined. That is, the envelope box is established by taking the tool represented by each tool axis vector, and the length and width are 1.5 times the radius in the tool coordinate system, and the height is the length of the tool handle. The tool in the workpiece coordinate system X W O W Y W The upper projection in the plane is a rectangle, in order to improve the calculation efficiency, the rectangular boundary of the tool projection range is simplified, that is, the projection rectangle is expanded into a cuboid region along the Zw direction of the workpiece coordinate system.

[0090] The coordinates of the envelope box vertices A, B, C, D, E, F, G and H in the workpiece coordinate system are calculated respectively, as shown in the following formula:

[0091]

[0092] Screening the detection points. Select the surfaces that may collide on the workpiece, and disperse these surfaces into a point cloud model, which is the detection area, and then perform point cloud filtering again, that is, any point Q i (x i ,y i ,z i ) in the detection area needs to meet Q i Full points in the above bounding box.

[0093] In order to determine whether the detection point Q and the tool interfere, that is, to judge whether the detection point Q is in the tool, the projection point Q1 of the point Q on the tool axis is set, and the coordinates of the projection point Q1 are calculated as:

[0094]

[0095] Wherein, κ is the distance coefficient of point Q1 to the center point M of the tool. Then, the vector QQ1 of point Q to point Q1 can be represented as:

[0096] QQ1=QM+κT (8)

[0097] Collision detection is performed on all tool axis vectors obtained in the foregoing step. Since the tool is a ball-end mill, according to the tool geometry, it can be determined that when κ > L or κ < -R, it indicates that the to-be-detected point Q is completely outside the tool model, and the point Q will not interfere with the tool. When -R≤κ≤L, it indicates that the to-be-detected point is in a range in which interference with the tool model can occur, and therefore it is necessary to carefully determine whether the to-be-detected point is inside the tool.

[0098] In the further determination process, when -R≤κ≤0, ||QM|| is calculated. If ||QM|| < R is satisfied, the to-be-detected point is inside the tool ball head, and the point Q interferes with the tool. Otherwise, the to-be-detected point is not inside the tool ball head, and the point Q does not interfere with the tool. When 0≤κ≤L, ||QQ' || is calculated. If ||QQ' || < R is satisfied, the to-be-detected point is inside the tool shank, and the point Q interferes with the tool. Otherwise, the to-be-detected point is not inside the tool shank, and the point Q does not interfere with the tool.

[0099] According to the interference determination criterion, it is determined whether the given tool axis vector is a non-interference feasible tool axis vector. If no interference occurs, the rake angle θ i and the tilt angle β j are recorded. i The interference determination is performed on the roll angles in the entire value range corresponding to the given rake angle θ i , and the roll angles corresponding to the non-interference tool axis vectors are recorded to determine the roll angle feasible region corresponding to the given rake angle in the entire value range. The tool axis vector corresponding to each rake angle and roll angle is the non-interference tool axis vector feasible region Ω of the given tool contact point P(u, v).

[0100] Let the tool axis vector at the i-th tool contact point be V i+1 , and the tool axis vector at the i+1-th tool contact point be V i . The tool axis vector change amount between the two adjacent tool contact points can be represented by the included angle θ between the tool axis vectors as follows: θ(V i+1 , V i ) = arccos(V i+1 , V max ). The sum s of the overall tool axis vector change amount on the tool contact point sequence can be represented as:

[0101]

[0102] Taking the minimum tool axis vector change amount in the tool feed direction as the optimization objective, the following smoothness optimization model is constructed:

[0103]

[0104] In the above formula, C is the set of nodes in the feasible region; θ max is a threshold value of the adjacent tool axis vector change obtained according to the feed speed and the tool path step length.

[0105] The directed graph of tool axis vectors is established according to the order of tool contact points in processing. It is assumed that each feasible tool axis vector is a vertex in the directed graph, and the vertex P i belongs to the set C(P i ) only, and the vertices in two adjacent sets can be arbitrarily associated, and the connecting line between two vertices is called an arc; the variation θ(V i , V i+1 ) of adjacent tool axis vectors is set as the weight of the arc; if θ(V i , V i+1 ) exceeds the maximum variation threshold θ max of the tool axis vector at the adjacent tool contact point, the arc is set as invalid and is removed from the directed graph, thereby establishing a weighted directed graph.

[0106] After the directed graph is established, the connectivity of the initial tool axis vector and each tool axis vector at the end point of the tool contact point trajectory is detected. The search is performed forward along the feed direction of the tool contact point trajectory from the initial point, the minimum weight of each vertex to the initial point is calculated and recorded; the weight of the initial point to all feasible tool axis vectors at the second tool contact point is calculated and recorded; the search is performed forward in turn until the end of the trajectory. Finally, the weights of each path at the end are compared, and the corresponding shortest path is found.

[0107] The moving window weighted smoothing is performed on the tool axis vectors in the processing path. According to formula (11), each tool axis vector is smoothed and corrected, the first and last t / 2 tool axis vectors are smoothed by the first and last moving windows; the tool axis vectors between the first and last t / 2 tool axis vectors are smoothed according to the window movement, and finally the smoothed tool axis vectors in the entire processing path are obtained.

[0108]

[0109] Example 2

[0110] On the basis of example 1, the embodiment further provides a tool axis vector optimization device, which comprises a memory, a processor, and a computer program stored in the memory and running on the processor, and when the processor executes the computer program, the tool axis vector optimization device realizes the blade machining tool axis vector solving method based on hierarchical non-interference feasible region as described above, and further generates the tool axis vector of the shortest machining path that can meet the non-collision, fairness and smoothness constraints in the blade machining process.

[0111] The tool axis vector optimization device in the embodiment is actually a data processing module for optimizing the working parameters of a five-axis machine tool in the process of machining a blade. Before machining each workpiece, the optimization device is used to efficiently solve the optimal tool axis vector under the condition of no interference in the machining path, and then the machine tool is controlled to complete the machining of the workpiece according to the solving result.

[0112] The tool axis vector optimization device is essentially a computer device. The computer device can be an embedded device, a tablet computer, a notebook computer, a desktop computer, a rack server, a blade server, a tower server or a cabinet server (including a single server or a server cluster composed of multiple servers), etc. which can execute programs.

[0113] The computer device of the embodiment at least includes but is not limited to a memory and a processor which can be connected to each other in communication through a system bus. In the embodiment, the memory (i.e. a readable storage medium) includes a flash memory, a hard disk, a multimedia card, a card-type memory (e.g. an SD or DX memory, etc.), a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a magnetic disk, an optical disk, etc. In some embodiments, the memory can be an internal storage unit of the computer device, such as a hard disk or a memory of the computer device. In other embodiments, the memory can also be an external storage device of the computer device, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the computer device. Of course, the memory can include both the internal storage unit and the external storage device of the computer device. In the embodiment, the memory is usually used to store the operating system and various application software installed on the computer device, etc. In addition, the memory can also be used to temporarily store various data that have been output or will be output.

[0114] The processor in some embodiments can be a central processing unit (CPU), a controller, a microcontroller, a microprocessor, or other data processing chips. The processor is usually used to control the overall operation of the computer device.

[0115] Test experiments

[0116] In order to verify the performance of the tool axis vector solving method based on hierarchical interference-free feasible region designed in the application, the technical personnel take an AC double-turntable tool axis machine tool as an example to solve the tool axis vector of blade machining based on the hierarchical interference-free tool axis vector feasible region of the blade machining tool.

[0117] I. Experimental Procedure

[0118] In this experiment, the flowchart for solving the feasible region of the tool axis vector without interference at the tool contact point is as follows: Figure 1 As shown, Figure 2 A schematic diagram of hierarchical retrieval of the non-interference cutter axis vector on the blade of the bladed disk. Figure 2 The process of solving the cutter shaft vector during the machining of the blades of the impeller disk includes the following steps:

[0119] (1) Establish the tool contact coordinate system and discretize the tool axis vector in stages:

[0120] by Figure 2 Taking the blade as an example, a ball end mill with a radius of 2mm and a shank length of 50mm is selected as the cutting tool, and a single-tool contact point coordinate system is established. The tool contact point information is obtained by the technical personnel through software development. For any tool contact point P, the rake angle is divided into 15 parts based on the rake angle (-π / 2, π / 2) and the side rake angle, and the side rake angle is divided into the same dimensions. The tool position point O corresponding to the tool contact point P is calculated by formula (1). L Formulas (2)-(4) are used to obtain the tool axis vector T corresponding to each pair of tool attitude angles. i .

[0121] (2) Solving for the feasible region of the non-interference tool axis vector at a single tool contact point:

[0122] Based on all tool axis vectors divided by a single tool contact point, a corresponding tool position coordinate system is established at the tool position OL according to formula (5). The coordinate vertices of the tool envelope represented by the tool axis vector are solved by formula (6), and then the sequence of points to be interfered with in the point cloud model obtained by workpiece triangulation mesh discretization is selected. According to formulas (7)-(8), the collision rule detection and judgment of the sequence of points to be interfered with is performed, and the feasible region Ω(uP,vP) of the tool axis vector without interference is selected. Figure 3 The diagram shows the feasible region of a single-point hierarchical non-interference tool axis vector. It is worth noting that the experimental scheme prioritizes calculating the tool axis vector within the interval β∈[0,π / 6]. If a non-interference tool axis vector is found within this interval, the tool axis vector within β∈(π / 6,π / 2] will not be calculated; conversely, it will progressively search β∈(π / 6,π / 4], (π / 4,π / 3], and (π / 3,π / 2] until a feasible region of a non-interference tool axis vector is found within a certain interval.

[0123] (3) Establish a solution model based on minimizing the change in the tool axis vector angle as the optimization objective, and solve for the tool axis vector in the blade machining path:

[0124] Based on the set of tool contact points C(P) in the machining path i The feasible region of the interference-free tool axis vector is obtained, and a system is established. Figure 4The diagram shows a directed graph of the tool axis vector. The box represented by the tool contact point Pi represents a node in the directed graph, and each vertex T in the node... i Indicates the knife contact point P i A feasible tool axis vector is found in the feasible region of the non-interference tool axis vector. Based on formulas (9)-(10), a solution model is established with the goal of minimizing the change in the angle of the tool axis vector at the tool contact point. The tool axis path with the minimum weight is calculated by substituting it into the directed graph.

[0125] (4) Construct a moving weighted smoothing model and solve for the smoothing tool axis vector of the machining path:

[0126] Based on formula (11), a moving weighted smoothing algorithm model is established, such as... Figure 5 As shown, 215 tool axis vectors from the single-layer machining path of the blade are used as inputs, with each ten vectors forming a smoothing window. These are then substituted into the moving weighted smoothing algorithm model to obtain the smooth tool axis vectors in the machining path.

[0127] II. Experimental Data and Analysis

[0128] The newly proposed method for solving the tool axis vector in bladed disk machining based on a hierarchical, interference-free feasible region was tested using a bladed disk model. The results are as follows: Figure 6 As shown, each vertical line represents a tool axis vector (tool position point and tool direction). Analysis Figure 6 It can be seen that the solution of this invention can guarantee the continuity of the tool axis vector in the machining path. Furthermore, the strategy of improving the tool contact coordinate system and hierarchically dividing the tool axis vector can greatly shorten the calculation time for solving the tool axis vector in the entire blade machining path. Figure 2 Taking the blade of a medium-sized disk as an example, the test calculated 2692 tool contact points across 7 layers of tool contact lines in 8.265 seconds, demonstrating a significant improvement in computational efficiency. Therefore, this method can be applied to practical industrial software to enhance the machining efficiency of five-axis machine tools.

[0129] Appendix Figure 7 The diagram shows a comparison of the tool axis vector change rate calculated by the present invention and the UG algorithm for the blade machining path. The X-axis represents the tool position sequence number, the Y-axis represents the angle of change of adjacent tool axis vectors, and the dashed line represents the tool axis vector change calculated by the UG algorithm. It can be seen that, compared to the tool axis vector change in UG, the tool axis vector calculated by the present invention fluctuates more gently during the machining of the blade pressure surface. This is reflected in the machine tool's rotating axis, where the acceleration changes smoothly, effectively suppressing vibration during blade machining.

[0130] In summary, the blade disk machining tool axis vector solution method based on hierarchical interference-free feasible region provided by this invention greatly improves the computational efficiency of tool axis vector solution and the stability of tool machining process while avoiding the problem of tool-workpiece geometric space interference.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified or some technical features therein can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for solving the blade disc machining tool axis vector based on hierarchical non-interference feasible region, characterized in that, It comprises the following steps: S1: based on the geometric characteristics of the blade disc workpiece, the tangent plane of the tool contact point is expressed as YOZ plane, and the corresponding tool contact coordinate system is established; S2: the movable space of the tool axis vector is divided in the tool contact coordinate system, the rake angle θ is divided into p dimensions, and the roll angle β is divided into q dimensions in four consecutive hierarchical intervals under the given rake angle, and then the tool axis vector T corresponding to each rake angle θ and roll angle β is determined according to the division result; S3: the projection section of the tool axis is the tool projection light receiving section, and the influence of the tool end face on the projection rectangle is considered, and the tool coordinate system is established as follows with the direction of the tool axis vector T as the Z axis direction; In the above formula, W1 is a unit vector representing the X-axis direction of the tool coordinate system, and W2 is a unit vector representing the Y-axis direction of the tool coordinate system; K W represents a unit vector in the Z-axis direction of the tool coordinate system; S4: the envelope box of the tool represented by each tool axis vector is established, and all the sets of detection points Q located in the envelope box are selected from the detection area; S5: the collision detection of all tool axis vectors in the hierarchical movable interval is judged; the interference is judged by traversing the roll angle in the given rake angle range, and the roll angle corresponding to the non-interference tool axis vector is recorded; and then the tool axis vector feasible region under the condition of non-interference of the tool contact point is obtained; S6: the smoothness optimization model of the overall tool axis vector is established with the tool axis vector change between two adjacent tool contact points as the optimization target; S7: the change of adjacent tool axis vectors is taken as the weight, and the weighted directed graph of the tool axis vector is established combined with the sequence of the tool contact point in machining; S8: the connectivity of the initial tool axis vector and the tool axis vector at the end point of the tool contact point trajectory is detected by Dijkstra algorithm, and the shortest machining path satisfying the smoothness optimization is solved; S9: the tool axis vector in the machining path is processed by moving window weighted smoothing, and the smooth tool axis vector in the whole machining path is finally obtained; In step S2, the expression of each tool axis vector T generated according to the division of the movable interval is as follows: In the above formula, i e represents the unit vector of the X-axis direction of the tool contact coordinate system; j e represents the unit vector of the Y-axis direction of the tool contact coordinate system; k e represents the unit vector of the Z-axis direction of the tool contact coordinate system; i and j represent the dimension numbers of the divided anteversion angle θ and the inclination angle β, respectively; 0≤i≤p, 0≤j≤q; the value range of the inclination angle β is: β∈[0, π / 6], (π / 6, π / 4], (π / 4, π / 3] and (π / 3, π / 2]; the value range of the anteversion angle θ is: θ∈(-π / 2, π / 2).

2. The blisk machining cutter axis vector solution method based on hierarchical non-interference feasible region according to claim 1, characterized in that, In step S1, the creation process of the tool contact coordinate system is as follows: S11: define the position coordinates of the tool contact point P, the normal vector of the tool contact point P on the surface is k, and the radius of the ball nose tool is R, then the position of the tool position point M in the workpiece coordinate system satisfies the following formula: M=P+Rk S12: project the tool contact point P onto the hub surface of the blade disc to obtain an auxiliary vector V; S13: project the vector V onto the tool contact tangent plane to obtain the vector Vz as the Z axis direction of the tool contact coordinate system; S14: the cross product of Vz and the tool contact tangent vector is obtained as the Y axis direction of the tool contact coordinate system; S15: the cross product of VZ and Vy is obtained as the X axis direction of the tool contact coordinate system.

3. The blisk machining cutter axis vector solving method based on hierarchical non-interference feasible region of claim 1, wherein: In step S4, the length and width of the envelope box are respectively 1.5 times the radius in the tool coordinate system, and the height is the length of the tool handle; the coordinates of the vertices of the envelope box are as follows: In the above formula, R T represents the ball head radius of the 1.5 times ball head milling cutter; L represents the shank length of the ball head milling cutter.

4. The blisk machining cutter axis vector solution method based on hierarchical non-interference feasible region of claim 1, wherein, In step S5, the collision detection process of the tool axis vector is as follows: (1) Project the tool in the workpiece coordinate system X W O W Y W onto the plane, to get a rectangular region; (2) determine whether the detection point Q and the tool interfere, that is, judge whether the detection point Q is in the tool, let Q1 be the projection point of Q on the tool axis, and the coordinates of the projection point Q1 are: In the formula, κ is the distance coefficient of point Q1 to tool position point M; MQ represents the vector from M point to Q point; At this time, the vector QQ1 from point Q to point Q1 can be expressed as: QQ1=QM+κT In the above formula, QM represents a vector from Q point to M point; (3) According to the vectors QQ1 and QM, the following judgment is made: A: When κ>L or κ<-R, it means that the to-be-detected point Q is completely outside the tool model, and Q will not interfere with the tool; B: When -R≤κ≤L, it means that the to-be-detected point is in a range where interference with the tool model is possible; further judgment is made as follows: b1: When -R≤κ≤0, ||QM|| is calculated, and when ||QM||<R, the to-be-detected point is inside the tool ball head, and Q interferes with the tool; On the contrary, the to-be-detected point is not inside the ball head, and Q does not interfere with the tool; b2: When 0≤κ≤L, ||QQ1|| is calculated, and when ||QQ1||<R, the to-be-detected point is inside the tool bar, and point Q interferes with the tool; on the contrary, the to-be-detected point is not inside the tool bar, and Q does not interfere with the tool.

5. The blisk machining cutter axis vector solution method based on hierarchical non-interference feasible region of claim 1, wherein: In step S6, let the tool axis vector at the ith tool contact point be V i , and the tool axis vector at the (i+1)th tool contact point be V i+1 . Then the tool axis vector variation between two adjacent tool contact points is represented by the included angle θ between the tool axis vectors as follows: θ(V i ,V i+1 ) = arccos(V i ,V i+1 ); The sum s of the overall tool axis vector variation on the tool contact point sequence can be represented as: Taking the minimum tool axis vector variation along the tool feed direction as the optimization objective, the following fairness optimization model is constructed: In the above formula, C is a set of nodes in the feasible region; θ max is a threshold value for the change in the adjacent tool axis vector obtained in common calculation according to the feed speed and the tool path step length.

6. The blisk machining cutter axis vector solution method based on hierarchical non-interference feasible region of claim 1, wherein: The construction method of the weighted directed graph of the tool axis vector in step S7 is as follows: Assume that each feasible tool axis vector is a vertex in a directed graph, and vertex P i All uniquely belong to set C(P) i If the vertices in two adjacent sets are arbitrarily related, the line connecting the two vertices is called an arc; the change θ(V) of the adjacent tool axis vectors is... i V i+1 ) is set to the weight associated with the arc; if θ(V i V i+1 The maximum change threshold θ of the tool axis vector at adjacent tool contact points is exceeded. max If the condition is met, the arc is set to invalid and removed from the directed graph, thus creating a weighted directed graph.

7. The blisk machining cutter axis vector solution method based on hierarchical non-interference feasible region of claim 1, wherein, The optimization method of the shortest machining path in step S8 is as follows: After the directed graph is established, the connectivity of each tool axis vector from the initial tool axis vector to the end point of the tool contact point trajectory is detected; and each vertex to the initial point is searched forward along the feed direction of the tool contact point trajectory, and the minimum weight value is calculated and recorded; The weight values of all feasible tool axis vectors from the initial point to the second tool contact point are calculated and recorded; Forward search is performed in turn until the end of the trajectory; finally, the weight values of each path at the end are compared to find the corresponding shortest machining path.

8. The blisk machining cutter axis vector solution method based on hierarchical non-interference feasible region of claim 1, wherein: The expression of the moving window weighted smoothing processing of the tool axis vector in the machining path is as follows: In the above equation, T m is the modified window center, w is the half-width of the moving window, and T m-i is the data within the window, w i is the weight coefficient for weighting the data within the window.

9. An apparatus for optimizing a tool axis vector, comprising a memory, a processor, and a computer program stored on the memory and running on the processor, characterized in that: When the processor executes the computer program, the method for solving the tool axis vector of the blade machining based on the hierarchical non-interference feasible region is realized, and the shortest machining path of the tool axis vector that can meet the non-collision, fairness and smoothness constraints in the blade machining process is generated.

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