A centrifugal wheel structure additive and subtractive composite manufacturing method and system

Abstract

The application provides a centrifugal wheel structure additive and subtractive composite manufacturing method and system, and belongs to the field of part manufacturing.The method comprises the following steps: establishing a three-dimensional model of a centrifugal wheel; performing feature decomposition on the three-dimensional model of the centrifugal wheel to obtain a bottom ring feature, a center ring feature, a top ring feature and a center disc feature; based on the bottom ring feature and the center ring feature, additive manufacturing is performed on the bottom ring and a preliminary center ring in a bottom-up and inside-out direction; based on the center disc feature, a preliminary center disc is rotationally and additively manufactured along a radial direction around the preliminary center ring; based on the center disc feature, a blade is additively manufactured inside the preliminary center disc in an additive and subtractive alternating manner, and the center disc is continuously additively manufactured along the radial direction; and based on the preliminary center ring and the top ring feature, the center ring and the top ring are additively manufactured in a bottom-up direction to obtain the centrifugal wheel structure.The application improves the manufacturing efficiency of the centrifugal wheel and the quality of the centrifugal wheel.

Description

Technical Field

[0001] This invention relates to the field of parts manufacturing, and in particular to a method and system for manufacturing centrifugal wheel structures using additive and subtractive materials. Background Technology

[0002] Additive manufacturing is an advanced manufacturing technology that discretizes a digital 3D model into several 2D planar slices, and uses a coded program to drive a motion mechanism to stack materials layer by layer, ultimately forming a 3D part. It has the advantage of rapidly and directly forming complex parts. Subtractive manufacturing is a traditional machining technology that removes raw materials through machining methods such as turning and milling to ultimately form the desired part shape. It has high surface and shape accuracy.

[0003] However, additive manufacturing suffers from poor surface finish, while subtractive manufacturing can overcome the problems of poor surface quality and low dimensional accuracy associated with additive manufacturing alone. Furthermore, it can manufacture parts with complex internal cavities that traditional machining methods cannot produce. Therefore, composite additive and subtractive manufacturing is an advanced processing method with enormous potential for future manufacturing development.

[0004] The impeller is the key component of a centrifugal impeller, and its quality directly determines the performance of the equipment it is used in. However, the impeller's location is unique, and conventional casting techniques often result in various internal mechanical defects, such as porosity, residue, microfractures, and residual stress. Furthermore, conventional subtractive machining processes suffer from limitations such as confined internal spaces, limited tool access, and insufficient internal feed space, making it impossible to mill certain internal surfaces and the impeller surface. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for manufacturing centrifugal wheel structures using additive and subtractive materials, which can improve the manufacturing efficiency and quality of centrifugal wheels.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A method for manufacturing a centrifugal wheel structure using additive and subtractive materials composite manufacturing, wherein the centrifugal wheel structure includes a bottom ring, a top ring, a central ring, and a central disk. The bottom ring is fixedly connected to the lower surface of the central disk, and the top ring is fixedly connected to the upper surface of the central disk. The central disk has blades inside, and the central ring is fixedly connected to the central disk via the blades. The method for manufacturing the centrifugal wheel structure using additive and subtractive materials composite manufacturing includes:

[0008] Establish a three-dimensional model of the centrifugal impeller;

[0009] The three-dimensional model of the centrifugal wheel is decomposed to obtain the bottom ring feature, the center ring feature, the top ring feature, and the center disk feature;

[0010] Based on the bottom ring features and the center ring features, the bottom ring and the preliminary center ring are manufactured by additive manufacturing in a bottom-up and inside-out direction;

[0011] Based on the features of the central disk, an initial central disk is additively manufactured by rotating radially around the initial central ring;

[0012] Based on the features of the central disk, blades are manufactured inside the initial central disk using an alternating additive and subtractive manufacturing method, and the central disk is further manufactured radially using additive manufacturing.

[0013] Based on the features of the initial central ring and the top ring, the central ring and the top ring are additively manufactured from bottom to top to obtain a centrifugal wheel structure.

[0014] Optionally, based on the features of the central disk, blades are manufactured inside the initial central disk using an alternating additive and subtractive manufacturing method, specifically including:

[0015] A three-dimensional digital model of the central disk is established based on the features of the central disk.

[0016] An initial subtractive toolpath is generated based on the three-dimensional digital model of the central disk;

[0017] A three-dimensional digital model of the subtractive cutting tool is established based on a pre-set initial radius compensation value, and the three-dimensional digital model of the subtractive cutting tool is converted into a point cloud model.

[0018] Based on the three-dimensional digital model of the central disk and the point cloud model of the subtractive cutting tool, determine whether there is tool interference in the subtractive cutting tool under the initial subtractive cutting tool path;

[0019] If tool interference exists, the central disk feature is sliced ​​into layers, and the radius compensation value of the subtractive tool is adjusted according to each slice and the point cloud model of the subtractive tool to generate the subtractive tool trajectory.

[0020] If there is no tool interference, then the initial subtractive tool path is the subtractive tool trajectory;

[0021] Based on the subtractive tool path, blades are manufactured inside the initial central disk.

[0022] Optionally, an initial subtractive toolpath is generated based on the three-dimensional digital model of the central disk, specifically including:

[0023] Extract the edge coordinate points of the 3D digital model of the central disk;

[0024] Connect each edge coordinate point into a straight line or curve by means of grid scanning to generate an initial subtractive tool path.

[0025] Optionally, according to the 3D digital model of the central disk and the point cloud model of the subtractive tool, determine whether there is tool interference of the subtractive tool under the initial subtractive tool path, specifically including:

[0026] Perform a vertical projection on the 3D digital model of the central disk to obtain a projection area;

[0027] Intersect the projection area with the point cloud model of the subtractive tool to determine the intersection area;

[0028] Judge whether there is tool interference of the subtractive tool under the initial subtractive tool path according to the size relationship between the area of the intersection area and the milling allowance.

[0029] Optionally, if the area of the intersection area is equal to the milling allowance, there is no tool interference; if the area of the intersection area is greater than or less than the milling allowance, there is tool interference.

[0030] Optionally, according to each layer of slices and the point cloud model of the subtractive tool, adjust the radius compensation value of the subtractive tool to generate a subtractive tool trajectory, specifically including:

[0031] For the j-th iteration, establish the 3D digital model of the j-th layer of slices; 0 < j < J, where J is the total number of slices;

[0032] Judge whether there is tool interference of the subtractive tool at the j-th layer of slices according to the 3D digital models of the 1st to j-th layers of slices and the point cloud model of the subtractive tool;

[0033] If not, take the (j - 1)-th subtractive tool path as the j-th subtractive tool path, determine the subtractive tool trajectory of the 1st to j-th layers of slices according to the j-th subtractive tool path, and perform the (j + 1)-th iteration; the 0-th subtractive tool path is the initial subtractive tool path;

[0034] If there is, adjust the radius compensation value of the subtractive tool in the (j - 1)-th subtractive tool path to obtain the j-th subtractive tool path, and perform the (j + 1)-th iteration.

[0035] Optionally, judge whether there is tool interference of the subtractive tool at the j-th layer of slices according to the 3D digital models of the 1st to j-th layers of slices and the point cloud model of the subtractive tool, specifically including:

[0036] The 3D digital model of the slices from layer 1 to layer j is vertically projected to obtain the slice projection area;

[0037] The intersection area of ​​the slice projection region and the point cloud model of the subtractive cutting tool is determined.

[0038] If the area of ​​the intersecting region of the slices is equal to the milling allowance, then there is no tool interference at the j-th slice of the subtractive cutting tool; if the area of ​​the intersecting region of the slices is greater than or less than the milling allowance, then there is tool interference at the j-th slice of the subtractive cutting tool.

[0039] Optionally, adjust the radius compensation value of the subtractive tool in the (j-1)th subtractive toolpath, specifically including:

[0040] If the area of ​​the intersecting region of the slices is greater than the milling allowance, then reduce the radius compensation value of the subtractive tool in the (j-1)th subtractive tool path;

[0041] If the area of ​​the intersecting slices is less than the milling allowance, then increase the radius compensation of the subtractive tool in the (j-1)th subtractive tool path.

[0042] To achieve the above objectives, the present invention also provides the following solution:

[0043] A centrifugal wheel structure additive and subtractive composite manufacturing system includes:

[0044] The model building unit is used to create a three-dimensional model of the centrifugal impeller.

[0045] The feature decomposition unit, connected to the model building unit, is used to perform feature decomposition on the three-dimensional model of the centrifugal wheel to obtain the bottom ring feature, the center ring feature, the top ring feature, and the center disk feature.

[0046] The first additive manufacturing unit, connected to the feature decomposition unit, is used to additively manufacture the bottom ring and the preliminary center ring based on the bottom ring feature and the center ring feature, using an additive manufacturing direction from bottom to top and from inside to outside.

[0047] The second additive manufacturing unit, connected to the first additive manufacturing unit, is used to radially additively manufacture the preliminary central disk based on the features of the central disk, around the preliminary central ring.

[0048] An additive and subtractive manufacturing unit, connected to the second additive manufacturing unit, is used to manufacture blades inside the initial central disk using an alternating additive and subtractive manufacturing method based on the features of the central disk, and to continue additive manufacturing of the central disk radially;

[0049] The third additive manufacturing unit, connected to the additive-subtractive manufacturing unit, is used to additively manufacture the center ring and the top ring from bottom to top based on the features of the initial center ring and the top ring, so as to obtain the centrifugal wheel structure.

[0050] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0051] This invention first establishes a three-dimensional model of the centrifugal wheel, performs feature decomposition on the 3D model, and then, based on the features of the bottom ring and the central ring, uses additive manufacturing from bottom to top and from the inside to the outside to create the bottom ring and the initial central ring. Based on the features of the central disk, additive manufacturing is performed around the initial central ring in a radial direction around the initial central ring to create the initial central disk. Then, based on the features of the central disk, blades are manufactured inside the initial central disk using an alternating additive and subtractive manufacturing method, and additive manufacturing of the central disk continues in a radial direction. Finally, based on the features of the initial central ring and the top ring, additive manufacturing of the central ring and the top ring is performed from bottom to top to obtain the centrifugal wheel structure. By using an alternating additive and subtractive manufacturing method to create the blades inside the central disk, the problem of milling tool interference in complex and irregular structures is effectively avoided, ensuring the integrity of the part manufacturing process and improving the efficiency and quality of centrifugal wheel manufacturing. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a schematic diagram of the overall structure of the centrifugal impeller;

[0054] Figure 2 A flowchart illustrating the additive and subtractive composite manufacturing method for a centrifugal wheel structure provided in an embodiment of the present invention;

[0055] Figure 3 This is a flowchart illustrating the overall process of centrifugal wheel manufacturing.

[0056] Figure 4 A flowchart of the additive and subtractive manufacturing process;

[0057] Figure 5 This is a schematic diagram of the interference analysis process for subtractive manufacturing tools.

[0058] Figure 6 This is a schematic diagram of the interference projection of the cutting tool;

[0059] Figure 7 A schematic diagram of the process of selecting path points for a grid search;

[0060] Figure 8 This is a front view of the centrifugal impeller;

[0061] Figure 9 This is a 3D view of the centrifugal impeller;

[0062] Figure 10 This is a axial sectional view of the centrifugal wheel;

[0063] Figure 11 This is a top view of the blade structure inside the central disk of the centrifugal impeller;

[0064] Figure 12 This is a schematic diagram of the blade structure inside the central disk of the centrifugal wheel on the left side.

[0065] Figure 13 This is a schematic diagram of the module of the centrifugal wheel structure additive and subtractive composite manufacturing system of the present invention.

[0066] Symbol explanation:

[0067] Center ring-1, top ring-2, center disk-3, short blade-4, long blade-5, bottom ring-6, additive blade-7, generated path-8, tool-9, intersection area of ​​additive projection area and tool-10, mesh endpoint-11, subdivided mesh-12, candidate point at the tangent of the arc curve-13, candidate point at the perpendicular bisector of the midline of the straight line-14, model building unit-15, feature decomposition unit-16, first additive unit-17, second additive unit-18, additive and subtractive unit-19, third additive unit-20. Detailed Implementation

[0068] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0069] The purpose of this invention is to provide a method and system for additive and subtractive composite manufacturing of centrifugal wheel structures. By establishing a digital three-dimensional model of the centrifugal wheel and progressively decomposing the features of the three-dimensional model, a better basis is provided for real-time analysis of additive and subtractive interference. This solves the problems that traditional simple additive or subtractive manufacturing processes cannot form parts with complex internal cavity structures, the accuracy of formed parts is difficult to guarantee, the entire process of forming parts requires interference-free tool trajectory analysis, the generated additive and subtractive path planning is difficult and has low accuracy, and the auxiliary supports of complex embedded structures cannot be removed using traditional subtractive machining technology, thus making it impossible to construct complete parts.

[0070] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0071] like Figure 1 As shown, the centrifugal impeller structure includes a bottom ring 6, a top ring 2, a central ring 1, and a central disk 3. The bottom ring 6 is fixedly connected to the lower surface of the central disk 3, and the top ring 2 is fixedly connected to the upper surface of the central disk 3. The central disk 3 has blades inside, and the central ring 1 is fixedly connected to the central disk 3 via the blades. The blades inside the central disk 3 are divided into long blades 5 and short blades 4. The long blades 5 and short blades 4 are distributed on the inner surface of the central disk 3.

[0072] Example 1

[0073] like Figures 2-4 As shown, this embodiment provides a method for manufacturing a centrifugal wheel structure using additive and subtractive materials composites, including:

[0074] S1: Establish a three-dimensional model of the centrifugal impeller.

[0075] S2: Perform feature decomposition on the three-dimensional model of the centrifugal wheel to obtain the bottom ring feature, the center ring feature, the top ring feature, and the center disk feature.

[0076] In this embodiment, the key feature analysis lies in how the internal structure of the central disk connects to the top and bottom rings. The central ring is connected to the long blades and serves as the main support for the long blades; the central ring is neither in direct contact with the bottom ring nor with the central disk. The upper and lower surfaces of the central disk are separated by blades with curved surfaces, forming a complex internal flow channel structure that facilitates fluid flow.

[0077] This invention first digitizes the 3D model of a centrifugal wheel. Based on the overall structure of the centrifugal wheel and the concept of discretizing the 3D model entity, the 3D model is segmented to provide a feasible path pre-planning scheme for additive manufacturing. This ensures the accuracy of the timing of subtractive manufacturing intervention, better represents the growth behavior of the part, and facilitates further analysis of the internal structure of the centrifugal wheel, providing better preparation for subsequent path interference analysis and path planning. The model decomposition involves slicing the model to a certain thickness, the specific slice thickness depending on the characteristics of the actual model.

[0078] S3: Based on the bottom ring features and the center ring features, the bottom ring and the preliminary center ring are manufactured by additive manufacturing in a bottom-up and inside-out direction.

[0079] In this embodiment, the bottom support of the bottom ring and the center ring is manufactured longitudinally from bottom to top using additive manufacturing. Then, based on the bottom support of the center ring, the entire center ring is continued to be manufactured longitudinally from bottom to top to the upper surface of the center disk (i.e., the initial center ring).

[0080] S4: Based on the features of the central disk, a preliminary central disk is additively manufactured by radial rotation around the preliminary central ring. Specifically, blades are radially additively manufactured on the surface of the central ring. The printing nozzle gradually adds material around the central ring, while simultaneously printing supports at the long and short blades. The long blades gradually grow out first, followed by the short blades, while the blades receive sufficient support.

[0081] S5: Based on the features of the central disk, blades are manufactured inside the initial central disk using an alternating additive and subtractive manufacturing method, and the central disk is further manufactured radially using additive manufacturing.

[0082] In this embodiment, the additive manufacturing process is an additive-subtractive process that arranges the central disk from the inside out, which is different from the traditional bottom-up additive manufacturing direction. To a certain extent, this saves on the materials and processing time for adding supports, and also improves the manufacturability and manufacturing efficiency of the centrifugal wheel.

[0083] Specifically, the initial central ring serves as the main support for the additive manufacturing center disk, and additive manufacturing gradually proceeds as it rotates radially around the initial central ring. The central disk involves the addition and subtraction of long and short blades, which presents spatial interference issues with the tooling. Therefore, subtraction processes need to be introduced at opportune moments to ensure a smooth transition between additive and subtraction processes and guarantee the manufacturability of the part. Supports need to be added to the long blades while they are being added; similarly, supports must be added to the short blades while they are being added. When the long and short blades gradually grow around the central ring, additive and subtraction processes need to be alternated to ensure the manufacturing quality of the complex curved blade surfaces. Radial additive manufacturing and strengthening processes continue until the critical intermediate parts are fully formed, and finally, the inner cavity of the central disk is milled. At this point, the two main parts above the centrifugal wheel are complete, and the final additive and subtraction processes for the top ring are required.

[0084] S6: Based on the features of the initial central ring and the top ring, the central ring and the top ring are additively manufactured from bottom to top to obtain a centrifugal wheel structure.

[0085] Specifically, the direction is reversed, and the top and central rings are added vertically from bottom to top until the entire structure of the centrifugal wheel is completed. Finally, the substrate is cut off, the support portion of the central ring is removed, and the entire outer surface of the centrifugal wheel undergoes a subtractive finishing and strengthening process until all processes are completed.

[0086] The conventional approach to additive manufacturing is bottom-up, forming three-dimensional parts by layering materials. However, for parts with complex embedded structures, this traditional bottom-up approach often fails to achieve the desired manufacturing results. This is because the bottom-up method frequently requires adding sufficient support to the suspended structures to meet the additive requirements. Therefore, this invention employs a combination of additive and subtractive manufacturing techniques to produce centrifugal wheels, improving both manufacturing efficiency and quality.

[0087] Furthermore, the main focus of subtractive tool interference analysis on features is whether the subsequent direction of additive manufacturing is reasonable and whether the subsequent subtractive processes can guarantee precise intervention. The key is to analyze whether the decomposed features can be milled by subtractive machining, typically including milling the surface of the additive portion and the added supports. The main criterion is whether the tool radius compensation value is too large, preventing over-milling of the additive features and thus damaging the original part structure. In this embodiment, tool interference analysis uses 3D software to establish digital models of part features and tool features, further converting them into point cloud models to extract the point cloud coordinates of the part features and tool features, laying the groundwork for generating subtractive paths on the surface of the additive region.

[0088] S5 specifically includes:

[0089] S51: Establish a three-dimensional digital model of the central disk based on the features of the central disk.

[0090] S52: Generate an initial subtractive toolpath based on the three-dimensional digital model of the central disk.

[0091] Specifically, the path generation depends on the characteristics of the additive manufacturing region, such as the curved surface features of the blade. The 3D digital model of the central disk is converted into a point cloud model, and the point cloud coordinates of the additive manufacturing region surface are used as the basis for the subtractive manufacturing path. The edge coordinate points of the 3D digital model of the central disk are extracted, and the coordinate points are connected into straight lines or curves. Taking the first edge line as a reference, the initial subtractive toolpath is generated at equal intervals on the feature surface.

[0092] By combining point cloud coordinates to generate a path suitable for the current working conditions, it is beneficial for path planning of milling surfaces of parts with different thicknesses, and can adapt to path planning of complex curved surfaces, thus having certain practicality.

[0093] S53: Establish a three-dimensional digital model of the subtractive cutting tool based on the preset initial radius compensation value, and convert the three-dimensional digital model of the subtractive cutting tool into a point cloud model.

[0094] S54: Based on the three-dimensional digital model of the central disk and the point cloud model of the subtractive cutting tool, determine whether there is tool interference in the subtractive cutting tool under the initial subtractive cutting tool path.

[0095] Specifically, the point cloud coordinates of the tool are used for tool interference analysis to respectively determine the spatial range of the inner cavity that the tool can mill and the optimal movement range of the tool. One is to determine whether the inner cavity can be milled, and the other is to determine whether the best milling effect can be achieved to improve the accuracy of subtractive machining. The specific subtractive tool interference analysis is as Figure 5 shown.

[0096] The subtractive tool interference analysis mainly determines the spatial point cloud coordinates of the part features and the tool features, and performs spatial point cloud matching on the coordinates of the two. Based on the existing working conditions, a vertical projection is performed on the feature area to be added, and the intersection area of the tool feature and the added area feature under the projection is obtained. It is judged whether there is interference in the current subtractive tool path by the tool feature area and the intersection area. The schematic diagram of the intersection of the added area projection and the tool feature area is as Figure 6 shown. In the figure, 7 represents the added blade, 8 represents the generated path, 9 is the tool, and 10 is the intersection area of the added projection area and the tool.

[0097] First, a three-dimensional digital model of the central disk is vertically projected to obtain a projection area. Then, the projection area is intersected with the point cloud model of the subtractive tool to determine the intersection area. Finally, according to the size relationship between the area of the intersection area and the milling allowance (predetermined in advance), it is judged whether there is tool interference for the subtractive tool under the initial subtractive tool path. If the area of the intersection area is equal to the milling allowance, there is no tool interference; if the area of the intersection area is greater than or less than the milling allowance, there is tool interference.

[0098] S55: If there is tool interference, the central disk feature is sliced layer by layer, and according to each layer slice and the point cloud model of the subtractive tool, the radius compensation value of the subtractive tool is adjusted to generate a subtractive tool path. Furthermore, the integrity of each feature structure is ensured, and the accuracy and quality of the feature part are improved.

[0099] Specifically, (1) For the jth iteration, a three-dimensional digital model of the jth layer slice is established; 0 < j < J, where J is the total number of slices.

[0100] (2) According to the three-dimensional digital models of the first layer to the jth layer slices and the point cloud model of the subtractive tool, it is judged whether there is tool interference for the subtractive tool at the jth layer slice.

[0101] In this embodiment, the 3D digital model of slices from layer 1 to layer j is first vertically projected to obtain the slice projection area. Then, the slice projection area is intersected with the point cloud model of the subtractive cutting tool to determine the slice intersection area. If the area of ​​the slice intersection area is equal to the milling allowance, there is no tool interference at the layer j slice. If the area of ​​the slice intersection area is greater than or less than the milling allowance, there is tool interference at the layer j slice.

[0102] (3) If it does not exist, take the (j-1)th subtractive tool path as the jth subtractive tool path, determine the subtractive tool trajectory of the slice from layer 1 to layer j based on the jth subtractive tool path, and perform the (j+1)th iteration. The 0th subtractive tool path is the initial subtractive tool path.

[0103] (4) If it exists, adjust the radius compensation value of the subtractive cutting tool in the (j-1)th subtractive cutting tool path to obtain the j-th subtractive cutting tool path, and perform the (j+1)th iteration. Specifically, if the area of ​​the intersecting region of the slices is greater than the milling allowance, decrease the radius compensation value of the subtractive cutting tool in the (j-1)th subtractive cutting tool path. If the area of ​​the intersecting region of the slices is less than the milling allowance, increase the radius compensation amount of the subtractive cutting tool in the (j-1)th subtractive cutting tool path.

[0104] To better understand the solution of this invention, the tool interference in layered slicing will be further explained below.

[0105] Interference analysis of layered slicing is consistent with interference analysis of feature-based subtractive cutting tools. Feature-based layered slicing can be understood as a further subdivision step of feature-based tool interference analysis, involving addition and subtraction of material. The principle of layered slicing subdivision is based on the global interference analysis of feature decomposition. If local tool interference exists, the feature is further subdivided until there is no obvious tool interference between the tool and the feature.

[0106] Each subtractive tool interference analysis requires accumulating all slice layers before analysis to ensure the completeness of subsequent path planning. Tool analysis begins with the j-th slice of a specific feature (mainly the central disk). If there is no significant tool interference in the current slice layer, then j = j + 1, and j + 1 more slice layers are added downwards, accumulating all previous slices for tool interference analysis. If significant tool interference appears after accumulating the j-th slice, then all previous slices and the current j-th slice are accumulated, resulting in the additive and subtractive tool trajectory planning for the first j slices. Interference analysis continues for the remaining slices until the additive and subtractive tool trajectories for all slices are complete.

[0107] S56: If there is no tool interference, the initial subtractive tool path is the subtractive tool trajectory.

[0108] Specifically, if there is no obvious tool interference, the additive and subtractive tool trajectories for the central disk feature are automatically generated. Then, it is determined whether the additive and subtractive tool trajectories for all features conform to the expected manufacturing process. If all features conform to the expected manufacturing process, the entire additive-subtractive composite machining trajectory planning is complete. If the additive-subtractive tool trajectories for any feature do not conform to the expected manufacturing process, the tool interference analysis is repeated, and further subtractive tool interference analysis is performed for the remaining features until the entire additive-subtractive composite machining trajectory planning is complete.

[0109] S57: Based on the subtractive tool path, manufacture blades inside the initial central disk.

[0110] To better understand the solution of this invention, the path planning for additive and subtractive manufacturing will be further explained below.

[0111] (1) Path planning for additive and subtractive manufacturing based on feature decomposition mainly involves generating coded paths step-by-step according to the features of the centrifugal wheel 3D model using a mesh scanning approach based on the existing working conditions. The size of each mesh can be determined according to the actual working conditions. The endpoints of the meshes are recorded and connected into straight lines or circular arcs. Based on the connected straight lines, the points at the perpendicular bisectors of the lines are selected as candidate path points; based on the connected circular arcs, the points at the tangent points of the next mesh endpoint and the arc are selected as candidate path points. This facilitates path storage and online real-time programming adjustments, enabling real-time changes to the synchronous path and improving the efficiency and accuracy of path planning.

[0112] Specifically, the mesh scanning method primarily records the endpoints 11 of each subdivided mesh 12. To further optimize the possibility of real-time path editing, the endpoints between two meshes are connected, potentially forming a straight line or an arc. Whether the endpoints between two meshes form a straight line or a curve depends mainly on the distance between them. If the distance between the two endpoints is greater than or equal to the length of the mesh diagonal, the two endpoints are connected as a straight line; if the distance between the two endpoints is less than the length of the mesh diagonal, the two endpoints are connected as an arc. If the connection is a straight line, the midpoint of the perpendicular bisector of the line is selected as a candidate point 14 for the path; if the connection is an arc, the tangent point between the straight line extending from the endpoint of the next mesh and the arc is selected as a candidate point 13 for the path. The first endpoint in the path planning is determined based on the first coordinate point of the surface edge of the additive feature. A schematic diagram of the specific mesh division and the selection of candidate points for straight lines or arcs is shown below. Figure 7 As shown.

[0113] (2) Path planning for additive and subtractive manufacturing of slices is consistent with feature-based additive and subtractive manufacturing path planning. Layered slicing can be understood as a further subdivision of feature-based additive and subtractive manufacturing path planning; the principle of subdividing slice decomposition additive and subtractive manufacturing path planning is based on planning additive and subtractive manufacturing paths from global feature decomposition. For example... Figures 8-12 The diagram shown is a schematic of the centrifugal wheel structure manufactured according to the present invention.

[0114] This invention solves the problems of poor surface finish in additive manufacturing of centrifugal wheels with complex internal cavity and asymmetrical structures, as well as tool interference in traditional milling manufacturing. It fully considers the advantages of both additive and subtractive manufacturing processes, combining the two technologies by alternating between them to create complementary advantages and achieve high-performance additive-subtractive composite manufacturing of complex centrifugal wheel structures. After adding an appropriate number of layers, a subtractive process is introduced at an opportune time to perform high-precision subtractive machining on the inner cavity surfaces and internal support structures of the accumulated layers. This effectively avoids the problem of milling tool interference in complex and asymmetrical structures, ensuring the integrity of the part manufacturing process and improving the precision and quality of centrifugal wheel manufacturing.

[0115] Example 2

[0116] In order to implement the method corresponding to Embodiment 1 above and achieve the corresponding functions and technical effects, a centrifugal wheel structure additive and subtractive composite manufacturing system is provided below.

[0117] like Figure 13 As shown, the centrifugal wheel structure additive and subtractive composite manufacturing system provided in this embodiment includes: a model building unit 15, a feature decomposition unit 16, a first additive manufacturing unit 17, a second additive manufacturing unit 18, an additive and subtractive manufacturing unit 19, and a third additive manufacturing unit 20.

[0118] Among them, the model building unit 15 is used to build a three-dimensional model of the centrifugal wheel.

[0119] The feature decomposition unit 16 is connected to the model building unit 15. The feature decomposition unit 16 is used to perform feature decomposition on the three-dimensional model of the centrifugal wheel to obtain the bottom ring feature, the center ring feature, the top ring feature and the center disk feature.

[0120] The first additive manufacturing unit 17 is connected to the feature decomposition unit 16. The first additive manufacturing unit 17 is used to manufacture the bottom ring and the preliminary center ring by additive manufacturing in a bottom-up and inside-out direction based on the bottom ring feature and the center ring feature.

[0121] The second additive manufacturing unit 18 is connected to the first additive manufacturing unit 17. The second additive manufacturing unit 18 is used to add a preliminary central disk by radially rotating around the preliminary central ring based on the features of the central disk.

[0122] The additive and subtractive manufacturing unit 19 is connected to the second additive manufacturing unit 18. The additive and subtractive manufacturing unit 19 is used to manufacture blades inside the initial central disk by alternating additive and subtractive manufacturing based on the features of the central disk, and to continue additive manufacturing of the central disk in the radial direction.

[0123] The third additive manufacturing unit 20 is connected to the additive and subtractive manufacturing unit 19. The third additive manufacturing unit 20 is used to manufacture the center ring and the top ring from bottom to top based on the features of the initial center ring and the top ring, so as to obtain the centrifugal wheel structure.

[0124] Compared with the prior art, the centrifugal wheel structure additive and subtractive composite manufacturing system provided in this embodiment has the same beneficial effects as the centrifugal wheel structure additive and subtractive composite manufacturing method provided in Embodiment 1, and will not be repeated here.

[0125] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0126] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for manufacturing a centrifugal wheel structure using additive and subtractive materials, the centrifugal wheel structure comprising a bottom ring, a top ring, a central ring, and a central disk, wherein the bottom ring is fixedly connected to the lower surface of the central disk, the top ring is fixedly connected to the upper surface of the central disk, blades are provided inside the central disk, and the central ring is fixedly connected to the central disk via the blades, characterized in that... The centrifugal wheel structure additive and subtractive composite manufacturing method includes: Establish a three-dimensional model of the centrifugal impeller; The three-dimensional model of the centrifugal wheel is decomposed to obtain the bottom ring feature, the center ring feature, the top ring feature, and the center disk feature; wherein, the model is decomposed by slicing according to a certain thickness, and the specific slice thickness depends on the features of the actual model; Based on the bottom ring features and the center ring features, the bottom ring and the preliminary center ring are manufactured by additive manufacturing in a bottom-up and inside-out direction; specifically, the bottom support of the bottom ring and the center ring is manufactured by vertical additive manufacturing from bottom to top, and then based on the bottom support of the center ring, the entire center ring is manufactured by vertical additive manufacturing from bottom to top to the upper surface of the center disk to obtain the preliminary center ring. Based on the features of the central disk, the initial central disk is manufactured by radially rotating additive manufacturing around the initial central ring; specifically, blades are radially added to the surface of the central ring, and the printing nozzle gradually adds material around the central ring, while simultaneously printing supports at the long and short blades, with the long blades growing out first, followed by the short blades. Based on the features of the central disk, blades are manufactured inside the initial central disk using an alternating additive and subtractive manufacturing method, and the central disk is further manufactured radially using additive manufacturing. Based on the features of the initial central ring and the top ring, the central ring and the top ring are additively manufactured from bottom to top to obtain the centrifugal wheel structure; specifically, the direction is changed, and the top ring and the central ring are additively manufactured longitudinally from bottom to top until the entire structure of the centrifugal wheel is completed; finally, the substrate is cut off, the support part of the central ring is removed, and the entire outer surface of the centrifugal wheel is subjected to a subtractive finishing and strengthening treatment until all processes are completed; Specifically, based on the features of the central disk, blades are manufactured inside the initial central disk using alternating additive and subtractive manufacturing methods, including: A three-dimensional digital model of the central disk is established based on the features of the central disk. An initial subtractive toolpath is generated based on the three-dimensional digital model of the central disk; A three-dimensional digital model of the subtractive cutting tool is established based on a pre-set initial radius compensation value, and the three-dimensional digital model of the subtractive cutting tool is converted into a point cloud model. Based on the 3D digital model of the central disk and the point cloud model of the subtractive cutting tool, it is determined whether there is tool interference in the initial subtractive cutting tool path. Specifically, this includes: vertically projecting the 3D digital model of the central disk to obtain a projection area; intersecting the projection area with the point cloud model of the subtractive cutting tool to determine the intersection area; and determining whether there is tool interference in the initial subtractive cutting tool path based on the relationship between the area of ​​the intersection area and the milling allowance. If tool interference exists, the central disk feature is sliced ​​into layers, and the radius compensation value of the subtractive tool is adjusted according to each slice and the point cloud model of the subtractive tool to generate the subtractive tool trajectory. If there is no tool interference, then the initial subtractive tool path is the subtractive tool trajectory; Based on the subtractive tool path, blades are manufactured inside the initial central disk.

2. The method for manufacturing a centrifugal wheel structure using additive and subtractive materials according to claim 1, characterized in that, The initial subtractive toolpath is generated based on the three-dimensional digital model of the central disk, specifically including: Extract the edge coordinates of the three-dimensional digital model of the central disk; The initial subtractive toolpath is generated by connecting the coordinate points of each edge into a straight line or curve using a mesh scanning method.

3. The method for manufacturing a centrifugal wheel structure using additive and subtractive materials according to claim 1, characterized in that, If the area of ​​the intersecting region is equal to the milling allowance, there is no tool interference; if the area of ​​the intersecting region is greater than or less than the milling allowance, there is tool interference.

4. The method for manufacturing a centrifugal wheel structure using additive and subtractive materials according to claim 3, characterized in that, Based on the point cloud model of each slice and the subtractive cutting tool, the radius compensation value of the subtractive cutting tool is adjusted to generate the subtractive cutting tool trajectory, specifically including: Regarding the first j In the next iteration, establish the first... j A three-dimensional digital model of a slice; 0< j < J , J The total number of slices; According to the first floor to the second floor j Based on the three-dimensional digital model of the sliced ​​layer and the point cloud model of the subtractive cutting tool, determine the subtractive cutting tool in the first layer. j Is there tool interference at the slice section? If it does not exist, then the first j -1 subtractive toolpath as the first j The subtractive toolpath, according to the first j The subtractive machining toolpath determines the first to the second layer. j Subtractive cutting tool path for layer slicing, performing the first... j +1 iterations; the 0th subtractive toolpath is the initial subtractive toolpath; If it exists, then adjust the first... j The radius compensation value of the subtractive tool in the -1 subtractive toolpath is obtained to obtain the first... j The first subtractive toolpath, and the second... j +1 iterations.

5. The method for manufacturing a centrifugal wheel structure using additive and subtractive materials according to claim 4, characterized in that, According to the first floor to the second floor j Based on the three-dimensional digital model of the sliced ​​layer and the point cloud model of the subtractive cutting tool, determine the subtractive cutting tool in the first layer. j Does tool interference exist at the layer slice location? Specifically, this includes: From the 1st floor to the 2nd floor j The 3D digital model of the slice is vertically projected to obtain the slice projection area; The intersection area of ​​the slice projection region and the point cloud model of the subtractive cutting tool is determined. If the area of ​​the intersecting region of the slices is equal to the milling allowance, then the subtractive cutting tool in the first... j There is no tool interference at the slice layer; if the area of ​​the intersecting region of the slices is greater than or less than the milling allowance, the subtractive cutting tool at the first slice layer... j Tool interference exists at the layer slice location.

6. The method for manufacturing a centrifugal wheel structure using additive and subtractive materials according to claim 5, characterized in that, Adjustment j -1 radius compensation value for the subtractive tool in a subtractive toolpath, specifically including: If the area of ​​the intersecting region of the slices is greater than the milling allowance, then reduce the first... j -1 radius compensation value for the subtractive tool in a subtractive toolpath; If the area of ​​the intersecting region of the slices is less than the milling allowance, then increase the first... j -1 Radius compensation amount of the subtractive tool in a subtractive toolpath.

7. A centrifugal wheel structure additive-subtractive composite manufacturing system, applied to the centrifugal wheel structure additive-subtractive composite manufacturing method according to any one of claims 1-6, characterized in that, The centrifugal wheel structure additive and subtractive composite manufacturing system includes: The model building unit is used to create a three-dimensional model of the centrifugal impeller. The feature decomposition unit, connected to the model building unit, is used to perform feature decomposition on the three-dimensional model of the centrifugal wheel to obtain the bottom ring feature, the center ring feature, the top ring feature, and the center disk feature. The first additive manufacturing unit, connected to the feature decomposition unit, is used to additively manufacture the bottom ring and the preliminary center ring based on the bottom ring feature and the center ring feature, using an additive manufacturing direction from bottom to top and from inside to outside. The second additive manufacturing unit, connected to the first additive manufacturing unit, is used to radially additively manufacture the preliminary central disk based on the features of the central disk, around the preliminary central ring. An additive and subtractive manufacturing unit, connected to the second additive manufacturing unit, is used to manufacture blades inside the initial central disk using an alternating additive and subtractive manufacturing method based on the features of the central disk, and to continue additive manufacturing of the central disk radially; The third additive manufacturing unit, connected to the additive-subtractive manufacturing unit, is used to additively manufacture the center ring and the top ring from bottom to top based on the features of the initial center ring and the top ring, so as to obtain the centrifugal wheel structure.

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