A method and product for compensating for contour errors in five-axis machining of impeller and disk-type parts.

Abstract

This invention discloses a method and product for contour error compensation in five-axis machining of impeller disk-type parts, relating to the field of precision CNC machining technology. The invention first acquires point cloud data of a preliminary machining sample based on theoretical toolpaths. After preprocessing including denoising and coordinate registration, the actual machining surface is reconstructed. The actual machining surface is then accurately calculated by registering and comparing the data with the theoretical surface. Next, based on the contour deviation value, the toolpath is compensated for using the kinematic characteristics of the five-axis CNC machine tool, and the tool attitude is adjusted. Combined with balancing, adaptive correction of the toolpath is achieved, thus enabling effective control of contour errors in subsequent machining.

Description

Technical Field

[0001] This invention relates to the field of precision CNC machining technology, specifically to: 1. a method for compensating for contour errors in five-axis machining of impeller and disk-type parts; 2. a computer program product. Background Technology

[0002] Impeller and bladed disk components are key parts in aerospace propulsion systems. Their blades are often complex, twisted, free-form surfaces. Generally, theoretical toolpaths are calculated based on theoretical models, and machining is performed using a five-axis CNC machine tool according to these theoretical toolpaths (roughing followed by finishing). However, during actual finishing, factors such as geometric errors of the five-axis CNC machine tool, tool wear, part deformation caused by cutting forces, and thermal deformation can easily lead to significant discrepancies between the actual machined contour and the theoretical model, potentially resulting in part scrap.

[0003] Existing methods for compensating for the aforementioned errors have the following shortcomings, resulting in unsatisfactory error compensation effects: 1) Existing methods mostly focus on the static correction of geometric errors of five-axis CNC machine tools, ignoring the surface deformation errors generated dynamically during the machining process.

[0004] 2) Existing methods mostly use triangular mesh fitting for point cloud data processing, which makes it difficult to accurately characterize the smoothness of the blade's freeform surface.

[0005] 3) Existing methods do not fully consider the multi-axis collaborative constraints of five-axis CNC machine tools when compensating for toolpaths, which can easily lead to axis linkage interference or insufficient toolpath smoothness after compensation.

[0006] 4) Existing methods often use approximation to calculate errors, which makes it difficult to accurately reflect the true distribution of profile deviations.

[0007] Therefore, there is an urgent need to develop an integrated method that combines high-precision surface reconstruction, accurate error characterization, and multi-axis collaborative compensation to solve the error problem in machining impeller and disk-type parts on five-axis CNC machine tools. Summary of the Invention

[0008] Therefore, it is necessary to provide a contour error compensation method and product for five-axis machining of impeller and impeller parts, addressing the problem that the existing error compensation effect for machining impeller and impeller parts on five-axis CNC machine tools is not good.

[0009] This invention is achieved using the following technical solution: In a first aspect, this invention discloses a contour error compensation method for five-axis machining of impeller-disc type parts, used to correct the finishing error of the target part under five-axis CNC machine tool machining. The target part is an impeller-disc type part.

[0010] Methods for compensating for contour errors in five-axis machined impeller and disk parts include: Step 1: Machining a preliminary sample using a five-axis CNC machine tool according to the theoretical toolpath of the target part; Step 2: Perform a full-area scan on the initial processed sample to obtain the original point cloud data, and preprocess it to remove noise and complete coordinate registration with the theoretical model of the target part to obtain the corrected point cloud data. Step 3: Reconstruct the surface based on the corrected point cloud data to fit the actual processed surface; Step four involves registering and comparing the actual machined surface with the theoretical model of the target part to solve for the theoretical toolpath. K Contour deviation value of each tool position; Step 5: Based on the contour deviation value of each tool position, perform position compensation and tool posture adjustment on the corresponding tool position to obtain the compensated toolpath. Then, smooth the compensated toolpath to obtain the corrected toolpath for subsequent machining.

[0011] The five-axis machining method for compensating for contour errors of impeller and disk-type parts implements the method or process according to embodiments of this disclosure.

[0012] Secondly, the present invention discloses a computer program product, comprising a computer program. When executed by a processor, the computer program implements the steps of the contour error compensation method for five-axis machining impeller disk-type parts as disclosed in the first aspect.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention first acquires point cloud data of the initial machining sample based on the theoretical toolpath, and then reconstructs the actual machining surface after denoising and coordinate registration. By registering and comparing with the theoretical surface, the contour deviation of each toolpath point is accurately solved. Then, based on the kinematic characteristics of the five-axis CNC machine tool, the tool position is compensated and the tool posture is adjusted according to the contour deviation value. In addition, the toolpath is adaptively corrected by balancing, thereby enabling effective control of contour error in subsequent machining.

[0014] 2. This invention can effectively improve the machining accuracy and surface quality of impeller and bladed disk parts, and is particularly suitable for the mass production of high-precision impellers and bladed disks in the aerospace field.

[0015] 3. In the surface reconstruction process, this invention first uses a shrinking wrapping algorithm to convert the point cloud into a triangular mesh to form a preliminary surface. Then, the QEM algorithm is used to reduce the number of triangular meshes while keeping the shape of the preliminary surface basically unchanged. Next, a combined optimization algorithm is used to convert the simplified triangular mesh into a topologically continuous quadrilateral base mesh that matches the contour of the part. Finally, NURBS modeling is performed based on the quadrilateral base mesh. This solves the problem of computational overload that easily occurs when directly using NURBS modeling for surface reconstruction, and significantly improves the efficiency of subsequent fitting. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0017] Figure 1 This is a flowchart of the contour error compensation method for five-axis machining of impeller disk-type parts provided in Embodiment 1 of the present invention; Figure 2 for Figure 1 Flowchart for step two; Figure 3 for Figure 1 Flowchart for step three; Figure 4 This is a schematic diagram of contour deviation value calculation provided in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram showing the comparison before and after toolpath compensation provided in Embodiment 1 of the present invention. Detailed Implementation

[0018] 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.

[0019] It should be noted that when a component is said to be "installed on" another component, it can be directly on the other component or it may be in a component that is centered on it. When a component is said to be "set on" another component, it can be directly set on the other component or it may also be in a component that is centered on it. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or it may also be in a component that is centered on it.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Example 1 See Figure 1 This embodiment 1 provides a contour error compensation method for five-axis machining of impeller and disk-type parts, applicable to industrial scenarios where five-axis CNC machine tools are used to machine parts with complex curved surfaces such as impellers and disks. Specifically, this contour error compensation method is used to correct the finishing errors of the target part (i.e., impeller and disk-type parts) under five-axis CNC machine tool machining.

[0022] like Figure 1 As shown, a method for compensating for contour errors in five-axis machined impeller disk-type parts includes the following steps: Step 1: A preliminary sample is machined using a five-axis CNC machine tool according to the theoretical toolpath of the target part.

[0023] As mentioned in the background section, the target part has a corresponding theoretical model (usually a three-dimensional digital model, often stored in STP format) and a corresponding theoretical toolpath (which consists of a series of smooth curves). K Each tool position has a distributed tool position point, and the information for each tool position point includes its position coordinates and the corresponding tool posture (usually stored as digital text).

[0024] Therefore, the specific process of step one is as follows: First, based on the control system of the five-axis CNC machine tool, the theoretical toolpath is converted into a CNC program (including G code, M code and axis motion commands) that conforms to the machine tool instruction format. At the same time, the axis travel and linkage constraints are checked to avoid overtravel or interference. Then, the machine tool is driven to work according to the CNC program to process the finished product - which serves as the initial processing sample.

[0025] Step 2: Perform a full-area scan on the initial processed sample to obtain the original point cloud data, and preprocess it to remove noise and complete coordinate registration with the theoretical model of the target part to obtain the corrected point cloud data.

[0026] Generally, it is recommended to use a laser scanning device to scan the entire area of ​​the initial processed sample (it can be set to scan along the leaf height direction), which will yield the original point cloud data - which is scattered, may contain noise interference, and has an uncertain coordinate system.

[0027] Therefore, step two involves preprocessing the raw point cloud data—see [link / reference] Figure 2 The specific steps are as follows: S201 uses statistical filtering to remove noise points from the original point cloud data.

[0028] Specifically, the statistical filtering process is as follows: For any point in the original point cloud data Q i : Find (KD-tree or octree structure is recommended to speed up the search) its Euclidean nearest neighbor. k points ( k Generally, a value of 10~20 is used to form a neighborhood point set. N k ( Q i ); i ∈[1, I ], I Represents the total number of points in the original point cloud data; calculates... Q i and N k ( Q i )middle k Local average distance of points .

[0029] In this way, by traversing all points of the original point cloud data, we obtain... I Local average distance .

[0030] based on Statistical analysis was performed to calculate the global average distance. μ Standard deviation σ .

[0031] Remove local average distance and μ The difference exceeds 3 σ Points identified as noise are discarded; the remaining points are retained as valid points, thus obtaining the noise-removed point cloud data.

[0032] Of course, if necessary, data verification can be added to examine whether there are missing data in key areas of the point cloud (such as the root, leading edge, trailing edge, and other areas with more prominent features of the part). If so, the noise reduction operation is canceled and the relevant parameters are adjusted and reprocessed; otherwise, the subsequent processing is carried out normally.

[0033] S202 uses the ICP algorithm to perform coordinate registration between the noise-removed point cloud data and the theoretical model of the target part.

[0034] Specifically, the processing procedure of the ICP algorithm is as follows: Multiple sets of matching reference point pairs are selected on the noise-removed point cloud data and the theoretical model of the target part (it is recommended to select points from locations with more significant features, such as the root, leading edge, and trailing edge of the part). The rotation matrix is ​​iteratively optimized by minimizing the sum of squared Euclidean distances between the two point clouds as the objective function. R Translation vector T The process continues until the error between two adjacent iterations meets the requirements (generally set to no more than 0.1μm, but can be adjusted according to the actual situation). This indicates that the point cloud data after noise removal has completed coordinate registration and unified the coordinate system with the theoretical model of the target part.

[0035] The objective function is expressed as follows: ; In the formula, N Indicates the total number of matching reference point pairs; P i Represents the matching reference point on the theoretical model; Q i This indicates that the point cloud data after noise removal contains... P i The corresponding matching reference point.

[0036] It should be noted that, R It is a 3×3 rotation matrix; T It is a translation vector of size 3×1.

[0037] Step 3: Reconstruct the surface based on the corrected point cloud data to fit the actual processed surface.

[0038] Surface reconstruction commonly uses NURBS (Non-Uniform Rational B-Splines) modeling. However, for this method, directly using NURBS modeling based on points in the corrected point cloud data for surface reconstruction can easily lead to computational overload due to the large number of points, making it only suitable for resource-intensive environments. Therefore, to balance resource consumption, step three can be recommended to use... Figure 3 The method shown: S301 uses a shrink wrapping algorithm to connect three points in the corrected point cloud data to form several triangular meshes, thereby forming a preliminary curved surface.

[0039] In other words, the initial surface is composed of a dense network of tiny triangular meshes (with side lengths typically controlled between 0.05 and 0.1 mm), numbering in the millions. The three vertices of each triangular mesh are points from the corrected point cloud data.

[0040] S302 uses the QEM algorithm to reduce the number of triangular meshes while keeping the initial surface shape basically unchanged.

[0041] Since the number of triangular meshes contained in the initial surface is still very large, directly using them to fit the surface still results in too much computation. Therefore, it is necessary to reduce the number of triangular meshes while keeping the shape of the initial surface basically unchanged.

[0042] The core of the QEM algorithm is calculating the vertex search error—which characterizes the impact of deleting a vertex from a triangular mesh on the initial surface shape. Thus, in each iteration, the QEM algorithm prioritizes deleting vertices with the least impact, thereby preserving the shape characteristics of the initial surface to the greatest extent possible.

[0043] The formula for calculating the top search error is as follows: ; ; In the formula, V This represents a vertex in a triangular mesh. F ( V ) indicates that it contains V A set of triangular meshes; f express F ( V A triangular mesh in ); K f express f The quadratic error matrix; n f express f The unit normal vector; p f express f A point on; x This represents the vertices after the contraction.

[0044] In other words, delete V Afterwards, they will recombine to form a triangular mesh and obtain x — That is equivalent to shrinking to a new position. Q V The smaller the value, the less the shape change, meaning it's safe to delete. V The smaller the impact, the better.

[0045] Through actual testing, the QEM algorithm can simplify the number of triangular meshes to 30%~50% of the original while keeping the initial surface shape basically unchanged, which significantly improves the efficiency of subsequent fitting.

[0046] S303 uses a combinatorial optimization algorithm to transform the simplified triangular mesh into a topologically continuous quadrilateral base mesh that matches the part profile.

[0047] Combinatorial optimization algorithms essentially involve arranging and combining simplified triangular meshes to form several quadrilaterals, thereby generating a quadrilateral base mesh. During this process, it's crucial to ensure that the boundaries of the quadrilateral base meshes maintain consistency with the contour of the target part to achieve topological continuity.

[0048] S304 uses NURBS modeling based on a quadrilateral base mesh to obtain the actual machined surface.

[0049] NURBS modeling mainly involves optimizing node vectors and solving for controlled vertices to construct continuous, actual machining surfaces.

[0050] Specifically: First select u , v To order p =3、 q Bicubic B-spline basis functions with a value of 3 are used to ensure the second-order parametric continuity of the reconstructed surface, avoiding abrupt changes in axis motion and cutting chatter during subsequent toolpath generation, while accurately reproducing the complex tortuous freeform surface features of the impeller blades; then, a quasi-uniform node vector conforming to the Clamped endpoint constraints is constructed. u , v Set the corresponding order at both the beginning and the end, and then add one heavy node (i.e.) p +1 zero p +1 1) Internal nodes are evenly distributed at equal intervals within the parameter domain to ensure consistent basis function support intervals and global fitting stability; then, based on the least squares principle, an optimization equation is constructed with the goal of minimizing the fitting residual—the objective is to minimize the sum of squared Euclidean distances between the fitted surface and the measured vertices; next, combining the expressions for bicubic B-spline basis functions and NURBS rational surfaces, the control vertices of the rational surface are obtained by solving. P ij Its corresponding weight factor ω ij The surface is then back into the NURBS rational surface expression to complete the surface fitting; finally, after passing the global parameter continuity check, the actual processed surface is obtained.

[0051] The expression for the optimization equation is as follows: ; In the formula, Represents the parameters of a NURBS rational surface; Q 4,i Represents the vertices of the quadrilateral base mesh. n This indicates the total number of quadrilateral base grids.

[0052] The expression for a NURBS rational surface is: ; In the formula, expressu Towards p B-spline basis functions; express v Towards q B-spline basis functions; , All satisfy the Cox-deBoor recurrence relation; ω ij >0; y , z Indicates the number of control points.

[0053] Step four involves registering and comparing the actual machined surface with the theoretical model of the target part to determine the contour deviation value of each tool point in the theoretical toolpath.

[0054] As mentioned above, the theoretical toolpath contains K Each cutter point. Therefore, step four specifically includes: S401, based on the theoretical toolpath... k For each tool position, find its theoretical surface point mapped onto the theoretical model and its reconstructed surface point mapped onto the actual machining surface. Then, use the shortest distance valve to calculate the distance between the theoretical surface point and the reconstructed surface point along the corresponding surface normal on the theoretical model, as the distance to the tool position. k Contour deviation value of each tool position; k ∈[1, K ].

[0055] S401 actually establishes a parameter domain mapping relationship between the theoretical model and the actual machined surface, so as to facilitate distance calculation in the parameter domain.

[0056] For easier understanding, please refer to Figure 4 , order the k The contour deviation value of each tool position point is e k Then its expression is: ; In the formula, ( u k , v k ) indicates the first k The parameter domain of each cutter position; S theo ( u k , v k ) indicates the first k The theoretical surface points corresponding to each tool position point; S act ( u k , vk ) indicates the first k The reconstructed surface points corresponding to each cutter position; n k express S theo ( u k , v k The unit normal vector of ).

[0057] So, if e k >0 indicates that the actual machined surface is convex, meaning the machining radius is insufficient; if e k >0 indicates that the actual machined surface is concave, meaning the machining range is excessive.

[0058] S402, traverse all tool positions of the theoretical toolpath to obtain the profile deviation value of each tool position.

[0059] S402 actually obtained K The contour deviation values ​​of each tool position point form a deviation distribution matrix. E =[ e 1, e 2, …, e K ].

[0060] So, when necessary, it is also possible to... E First, perform outlier removal (e.g., remove outliers). E For data where the profile deviation exceeds a reasonable range, interpolation is then used to complete the data (cubic spline interpolation is recommended) to ensure the continuity of the deviation distribution.

[0061] Step 5: Based on the contour deviation value of each tool position, perform position compensation and tool posture adjustment on the corresponding tool position to obtain the compensated toolpath. Then, smooth the compensated toolpath to obtain the corrected toolpath for subsequent machining.

[0062] Traditional error compensation simply compensates for the tool position based on the contour deviation value of the tool tip obtained above. This method does not consider the multi-axis motion coordination constraints of the five-axis CNC machine tool after compensation, and may lead to problems such as axis overtravel, cutting interference, and insufficient toolpath smoothness because the tool posture is not optimized after compensating for the tool tip point. Therefore, step five introduces multi-axis coordinated compensation, which takes into account the fully coupled linkage compensation of the tool position, tool axis, and machine tool motion of the five-axis CNC machine tool. It not only compensates for the tool position but also adjusts the tool posture.

[0063] Specifically, taking the first k Taking a single blade position as an example, we have: S501, based one k Calculate the toolpath compensation vector V k and the tool correction vector R k Superimpose them onto the original coordinates of the tool position. O k After obtaining the coordinates of the tool position point compensation O k1 .

[0064] in, V k for e k and n k The product; R k for n k , l k The difference between Δ R The product of; Δ R The tool radius correction amount can be obtained from tool wear detection data; l k This is the unit vector of the tool axis before compensation.

[0065] In other words, O k1 The expression is: ; In the formula, ; .

[0066] Thus, after completing the first k After position compensation of the first tool point, the new position of the first tool point is obtained. k Each tool position point—its corresponding tool axis unit vector is l k1 In order to maintain the optimal cutting angle and ensure stable cutting force, l k1 , n k The included angle needs to be with l k , n k The included angles remain consistent (both are) α 0), which also requires tool attitude angle compensation in the next step.

[0067] S502, based on the structure of a five-axis CNC machine tool, constructs a Paden-Kahan subproblem to solve a collaborative compensation problem for tool posture in order to achieve the first... k Tool posture adjustment at each tool position point.

[0068] S502 inherits the tool tip position compensation results from S501 and performs precise calculation and closed-loop compensation of the tool posture angle to address the tool axis attitude mismatch problem caused by position compensation, ensuring that the compensated toolpath fully meets the cutting process constraints, machine tool multi-axis linkage requirements, and machining safety requirements.

[0069] The S502 uses the forward and inverse kinematics model of a five-axis CNC machine tool as its mathematical foundation and employs the classic Paden-Kahan subproblem in robotics as its core solution tool to achieve closed-loop decoupled solution of the attitude compensation angles of two rotary axes, thereby realizing... α Iteration with 0 unchanged l k1 This ensures that the compensated toolpath is continuous and smooth, ultimately based on the iteratively derived... l k1 The tool attitude compensation angle is obtained by decomposing and transforming the coordinates in the machine tool coordinate system.

[0070] The specific compensation process is as follows: S5021, with n k Based on this, a parameter is generated within the cutting plane (generally formed by the surface normal, feed direction, and original tool axis) that satisfies... The unit vector of the tool axis l k1 This ensures that the cutting angles before and after compensation are completely consistent, and that the axis passes through... O k1 .

[0071] S5022, for l k1 Perform collision interference verification and motion singular configuration verification, and examine whether they meet the non-interference cutting constraint and machine tool motion feasibility constraint.

[0072] If any constraint exceeds the limit, then without changing... α Fine-tuning under the premise of 0 l k1 Repeat step S5022 until a result that meets the requirements is found. l k1 For ease of subsequent representation, those that meet the requirements will be... l k1 Represented as new_l k .

[0073] S5023, based on l k , new_l k The tool orientation compensation angle for the corresponding axis is obtained by decomposing and transforming the tool in the machine tool coordinate system to adjust the first axis.k Tool posture at each tool position point.

[0074] In this embodiment 1, the tool change of the five-axis CNC machine tool is achieved by the coordinated rotation of two rotary axes, A and C. These two axes are strongly kinematically coupled and cannot be solved independently. Therefore, S5023 transforms the attitude adjustment of the tool axis unit vector into an inverse kinematics problem of a series mechanism, and completes the decoupled solution of the tool attitude compensation angles of axes A and C based on the Paden-Kahan subproblem. Finally, the calculation formulas for the tool attitude compensation angles of axes A and C are: ; ; in, ω p , ω s These are the unit direction vectors for the A-axis and C-axis, respectively; c 11,k , c 22,k express l k Orthogonal decomposition components in the machine tool coordinate system; u 11,k , u 22,k express new_l k Orthogonal decomposition components in the machine tool coordinate system; s p , s s These are the rotation direction sign factors for the A-axis and C-axis, respectively (determined based on the machining radius, with a value of ±1).

[0075] Of course, if there are other situations due to changes in the cutting tools of a five-axis CNC machine tool, the above method can still be used to solve the problem, which will not be elaborated here.

[0076] After processing via S501~S502, the first... k Two types of information for each knife site.

[0077] S503, traversal K Each tool position point yields the compensated toolpath.

[0078] To ensure the smoothness of five-axis CNC machine tool control, the compensated toolpaths need to be smoothed (B-spline interpolation is recommended) to achieve continuity of the first derivatives between adjacent toolpath points, thus obtaining a corrected toolpath for subsequent machining. See also... Figure 5Compared to the theoretical toolpath, the modified toolpath provides a more precise guiding path. The finished product can then be machined using a five-axis CNC machine tool according to the modified toolpath (refer to step one, which will not be repeated here) – this is the product after contour error compensation, achieving closed-loop compensation of contour errors.

[0079] Example 2 This embodiment 2 discloses a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the steps of the contour error compensation method for five-axis machining impeller disk-type parts disclosed in embodiment 1.

[0080] The computer equipment can be either a mobile terminal or a fixed terminal. Examples of the former include mobile phones, laptops, digital radio receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), and in-vehicle terminals (such as in-vehicle navigation terminals); examples of the latter include digital TVs and desktop computers.

[0081] This embodiment 2 also discloses a readable storage medium that stores computer program instructions. When the computer program instructions are read and run by a processor, the steps of the contour error compensation method for five-axis machining impeller disk-type parts disclosed in embodiment 1 are executed.

[0082] The readable storage medium may include, but is not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination of the above.

[0083] This embodiment 2 also discloses a computer program product, including a computer program. When executed by a processor, the computer program implements the steps of the contour error compensation method for five-axis machining impeller disk-type parts disclosed in embodiment 1.

[0084] It should be noted that the computer program used to execute the above can be written in one or more programming languages ​​or a combination thereof. These programming languages ​​include object-oriented programming languages—such as Java, Smalltalk, and C++—as well as conventional procedural programming languages—such as C or similar languages. The computer program can be executed entirely on the user's computer, partially on the user's computer, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer through any type of network—including a Local Area Network (LAN) or a Wide Area Network (WAN).

[0085] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0086] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for compensating for contour errors in five-axis machining of impeller and disk-type parts, characterized in that, It is used to correct the finishing error of a target part under five-axis CNC machine tool machining; the target part is an impeller or bladed disk type part; the contour error compensation method includes: Step 1: Machining a preliminary sample using a five-axis CNC machine tool according to the theoretical toolpath of the target part; Step 2: Perform a full-area scan on the initial processed sample to obtain the original point cloud data, and preprocess it to remove noise and complete coordinate registration with the theoretical model of the target part to obtain the corrected point cloud data. Step 3: Reconstruct the surface based on the corrected point cloud data to fit the actual processed surface; Step four involves registering and comparing the actual machined surface with the theoretical model of the target part to solve for the theoretical toolpath. K Contour deviation value of each tool position; Step 5: Based on the contour deviation value of each tool position, perform position compensation and tool posture adjustment on the corresponding tool position to obtain the compensated toolpath. Then, smooth the compensated toolpath to obtain the corrected toolpath for subsequent machining.

2. The contour error compensation method for five-axis machined impeller disk-type parts according to claim 1, characterized in that, In step one, the theoretical toolpath includes: a series of smooth curves connected together. K There are several dispersed tool positions; the information for each tool position includes its position coordinates and the corresponding tool posture.

3. The contour error compensation method for five-axis machined impeller disk-type parts according to claim 1, characterized in that, In step two, a laser scanning device is used to scan the entire area of ​​the pre-processed sample; Or / and, preprocessing of raw point cloud data includes: First, noise points are removed from the original point cloud data using statistical filtering. Then, the point cloud data after noise removal is registered with the theoretical model of the target part using the ICP algorithm.

4. The contour error compensation method for five-axis machined impeller and disk-type parts according to claim 1, characterized in that, Step 3 directly uses NURBS modeling to reconstruct surfaces based on points in the corrected point cloud data.

5. The contour error compensation method for five-axis machined impeller disk-type parts according to claim 1, characterized in that, Step three includes: S301, the shrink wrapping algorithm is used to connect three points in the corrected point cloud data to form several triangular meshes, thereby forming a preliminary curved surface; S302 uses the QEM algorithm to reduce the number of triangular meshes while keeping the initial surface shape basically unchanged; S303 uses a combinatorial optimization algorithm to transform the simplified triangular mesh into a topologically continuous quadrilateral base mesh that matches the part contour. S304 uses NURBS modeling based on a quadrilateral base mesh to obtain the actual machined surface.

6. The method for compensating for contour errors in five-axis machined impeller and disk-type parts according to claim 1, characterized in that, Step four includes: S401, based on the theoretical toolpath... k For each tool position, find its theoretical surface point mapped onto the theoretical model and its reconstructed surface point mapped onto the actual machining surface. Then, use the shortest distance valve to calculate the distance between the theoretical surface point and the reconstructed surface point along the corresponding surface normal on the theoretical model, as the distance to the tool position. k Contour deviation value of each tool position; k ∈[1, K ]; S402, traverse all tool positions of the theoretical toolpath to obtain the profile deviation value of each tool position.

7. The method for compensating for contour errors in five-axis machined impeller disk-type parts according to claim 6, characterized in that, S402 also includes: right K Outlier values ​​for the contour deviation of each tool position are first removed, and then interpolation is used to complete the data to ensure the continuity of the deviation distribution.

8. The method for compensating for contour errors in five-axis machined impeller disk-type parts according to claim 1, characterized in that, Step five includes: S501, based on the first k Contour deviation value of each tool position e k Calculate the toolpath compensation vector V k and the tool correction vector R k Superimpose them onto the original coordinates of the tool position. O k After obtaining the coordinates of the tool position point compensation O k1 ; k ∈[1, K ]; in, ; ; ; n k express S theo ( u k , v k The unit normal vector of ). S theo ( u k , v k ) indicates the first k The theoretical surface points corresponding to each tool position point; u k , v k ) indicates the first k The parameter domain of each cutter position; Δ R This is the tool radius correction amount; l k The cutter axis unit vector before compensation; S502, based on the structure of a five-axis CNC machine tool, constructs a Paden-Kahan subproblem to solve a collaborative compensation problem for tool posture in order to achieve the first... k Tool posture adjustment at each tool position point; S503, traversal K Each tool position point yields the compensated toolpath.

9. The method for compensating for contour errors in five-axis machined impeller disk-type parts according to claim 8, characterized in that, S502 includes: S5021, with n k Based on this, generate a model within the cutting plane that satisfies... The unit vector of the tool axis l k1 ; α 0 is l k , n k The included angle; S5022, for l k1 Perform collision interference verification and motion singular configuration verification, and examine whether they meet the non-interference cutting constraints and machine tool motion feasibility constraints; If any constraint exceeds the limit, then without changing... α Fine-tuning under the premise of 0 l k1 Repeat step S5022 until a result that meets the requirements is found. new_l k ; S5023, based on l k , new_l k The tool orientation compensation angle for the corresponding axis is obtained by decomposing and transforming the tool in the machine tool coordinate system to adjust the first axis. k Tool posture at each tool position point.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the contour error compensation method for five-axis machining of impeller and disk-type parts as described in any one of claims 1-9.

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