Machining method and system for large-diameter impeller

Abstract

The invention relates to the technical field of machine tool machining, in particular to a large-diameter impeller machining method and system.The method comprises the steps that firstly, a pre-milling blank model is constructed according to the blade profile and blade tip condition of an impeller, a material removal area is determined after the pre-milling blank model is compared with a target machining model, and a pretreated blank is obtained; then, blade gaps are regarded as grooves, roughing is conducted through a layer milling cutter path, and a rough machining residual model is obtained; then a semi-finish machining and finish machining fusion strategy is adopted, allowance homogenization and forming machining are conducted on the rough machining residual model, and an impeller finish machining product is formed; then correcting a local tool path based on detection data, and controlling a blade profile tolerance error; and finally, root fillets are cut from the two ends to the middle, and smooth switching of the blade, the hub and the blade is achieved. According to the technology, through an innovative machining strategy and a closed-loop correction mechanism, the problems of low efficiency, out-of-tolerance chatter marks, unsmooth switching and the like in large-diameter impeller machining are effectively solved, and the machining quality and stability are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of machine tool processing, and in particular to a processing method and system for a large-diameter impeller. Background Art

[0002] As CNC machining technology continues to evolve towards high precision and intelligence, the five-axis linkage machining center, with its multi-degree-of-freedom motion control capabilities, has become the core equipment for the precision manufacturing of large-diameter impellers, significantly improving the machining accuracy and production efficiency of complex surfaces. In the machining process system, the layer milling strategy is the standard process for rough machining of the flow channel area of ​​small and medium-sized impellers, removing most of the machining allowances through layered cutting. However, when this strategy is applied to the rough machining of large-diameter impellers, due to their large size and complex structure, more cutting layers and tool trajectory paths need to be planned, resulting in a significant increase in machining time and a significant reduction in production efficiency; at the same time, the cutting conditions of large cutting depth and high feed rate place stringent requirements on the torque output capacity and structural rigidity of the machine tool, exacerbating the difficulty of process implementation during the machining process.

[0003] In the blade processing process, based on the distribution law of the profile allowance, the processing steps are usually divided into two stages: semi-finishing and finishing. The finishing process uses the residual allowance of the previous semi-finishing as the cutting object, aiming to achieve high-precision forming of the blade surface. However, the large-diameter impeller has the structural characteristics of the blade body overhang height of up to 450mm and the thin blade wall thickness, which leads to a significant lack of rigidity in the tip area. When using traditional processing technology for blade finishing, it is very easy to induce flutter under the excitation of cutting force, which in turn produces surface vibration defects and causes the blade profile to exceed the tolerance range, making it difficult to meet the design accuracy requirements. In addition, in the root fillet processing link of the blade, due to the coupling of multiple factors such as tool clamping error, cutting thermal deformation and the release of residual stress of the workpiece itself, traditional processing methods are difficult to ensure the smooth connection between the fillet transition area and the hub and blade profile, affecting the overall aerodynamic performance and structural strength of the impeller. Summary of the Invention

[0004] To this end, the technical problem to be solved by the present invention is to overcome the problems in the existing large-diameter impeller processing, such as the low efficiency of the layer milling strategy when used for rough processing and high requirements on machine tool performance, the traditional finishing method resulting in vibration marks and excessive contour due to the poor rigidity of the thin-walled structure of the blade, and the difficulty in smoothly transitioning the blade root fillet processing to the hub and blade due to the tool installation error and part deformation.

[0005] To solve the above technical problems, the present invention provides a method and system for processing a large-diameter impeller, the method comprising the following steps:

[0006] Step 1: Based on the actual geometric parameters of the impeller blade tip to be processed, a pre-milling blank model is constructed. This model is compared with the target impeller processing model that meets the requirements of milling processing, and the material area to be removed from the blank is determined to obtain the pre-processed blank model.

[0007] Step 2: Considering the gaps between the blades as slots, the pre-processed blank model is roughened using a layer milling type tool path to remove the material between the blades, leaving only a uniform roughing allowance, and obtain a roughing residual model;

[0008] Step 3: The rough machining residual model is subjected to allowance homogenization and forming processing by adopting a semi-finishing and finishing fusion method to obtain an impeller finishing product;

[0009] Step 4: performing local tool path correction processing on the impeller precision-machined product based on the detection data, so that the blade profile error is controlled within a preset tolerance range, and a blade profile qualified model is obtained;

[0010] Step 5: By adjusting the cutting sequence of the root fillet processing tool path from both ends to the middle, the root fillet area of ​​the blade contour qualified model is processed to obtain an impeller finished product with a smooth transition between the root fillet and the hub and blades.

[0011] In one embodiment of the present invention, in step 2, the method for obtaining the rough machining residual model includes:

[0012] The gaps between the blades are regarded as slots, and roughing is performed using a layer milling type tool path. The material removal process between the blades is decomposed into multiple cutting layers. The tool posture is locked by the fixed rotating axis of the machine tool, and the cutting parameters of the tool are adjusted. Each layer is cut back and forth along the inter-layer trajectory using the entire bottom surface of the tool according to the set cutting parameters, removing 80% to 90% of the material between the blades and retaining only a uniform roughing allowance, that is, the material thickness between the blade surface and the impeller target processing model is uniform, forming a preliminary blade contour and obtaining a roughing residual model.

[0013] In one embodiment of the present invention, the cutting parameters include feed rate and cutting depth.

[0014] In one embodiment of the present invention, in step 3, the method for obtaining the impeller finished product includes:

[0015] Through the blade disk layer milling roughing strategy, a five-axis linkage cutting method is adopted to mill the blade basin and blade back along the left and right sides of a single flow channel. The cutting direction is consistent with the blade profile line. The uneven allowance remaining after roughing is removed, and the blade surface allowance is uniformed within the preset processing range. The allowance of the lower half of the blade profile is retained. The blade rigidity is enhanced by the allowance support, forming a semi-finishing allowance uniform model.

[0016] Based on the uniform semi-finishing allowance model, the blade finishing strategy is utilized, and through five-axis linkage milling, the tool moves along the blade surface trajectory, gradually removing all the remaining residual materials after semi-finishing. The machining sequence is adjusted through the combined milling strategy to finally form the impeller finishing product.

[0017] In one embodiment of the present invention, in step 4, the method for obtaining a qualified blade profile model includes:

[0018] Obtain the contour data of the impeller precision-machined product through three-dimensional coordinate measurement or on-machine testing, and identify the local out-of-tolerance areas and deformation patterns caused by factors including tool overhang and machine tool yield;

[0019] Based on the local tolerance area and deformation law, the subsequent impeller finishing tool path is compensated and adjusted in advance, and the compensation value is directly integrated into the finishing tool path trajectory to generate an optimized finishing tool path trajectory;

[0020] The subsequent impeller is fine-machined once using the optimized fine-machining tool path trajectory, so that the blade profile error is controlled within a preset tolerance range, and a qualified blade profile model is obtained.

[0021] In one embodiment of the present invention, in step 5, the method for obtaining a finished impeller having a smooth transition between the root fillet and the hub and blades includes:

[0022] Using the root fillet finishing strategy, the tool mills around the root fillet, selecting one of the machining directions: from the hub to the blade or from the blade to the hub. By adjusting the cutting sequence to cut from both ends to the middle, the allowance at the angle between the blade profile twist angle and the flow channel is gradually removed at the preset cutting depth.

[0023] At the same time, the allowance of the fillet area is adjusted according to the processing requirements to ensure that the curvature of the root fillet processing area and the hub and blade profiles are continuous and without sudden changes, so as to obtain an impeller product with a smooth transition between the root fillet and the hub and blades.

[0024] In one embodiment of the present invention, a method for adjusting the allowance of the fillet area according to processing requirements to ensure that the curvature of the root fillet processing area and the hub and blade profiles are continuous and without sudden changes includes:

[0025] Define the blade and hub tool radius, select the down milling mode, set the tool axis angle, feed rate, and number of corner extra deceleration toolpaths;

[0026] During the machining process, the tool path trajectory is monitored and the curvature continuity of the fillet joint is checked. After machining, the contour of the fillet transition area is detected using a three-coordinate measuring machine. If a sudden change or deviation is found, the tool path is adjusted again using the variable allowance function until the tolerance control requirements for the smooth transition between the root fillet and the hub and blade are met.

[0027] Based on the same inventive concept, the present invention also provides a large-diameter impeller processing system, which includes: a pretreatment and blank preparation module, a cavity rough processing module, a combined milling and blade forming module, a contour detection and variable allowance correction module, and a root fillet smoothing processing module; wherein,

[0028] The pre-processing and blank preparation module is configured to: construct a pre-milling blank model based on the actual geometric parameters of the impeller blade tip to be processed, compare it with the target impeller processing model that meets the milling processing requirements, determine the material area to be removed from the blank, and obtain a pre-processed blank model;

[0029] The cavity rough machining module is configured to: consider the gaps between the blades as slots, roughen the pre-processed blank model using a layer milling type tool path, remove the material between the blades, and retain only a uniform rough machining allowance to obtain a rough machining residual model;

[0030] The combined milling and blade forming module is configured to: perform allowance homogenization and forming processing on the roughing residual model using a semi-finishing and finishing fusion method to obtain an impeller finishing product;

[0031] The contour detection and variable allowance correction module is configured to: perform local tool path correction processing on the impeller precision-machined product based on the detection data, so that the blade profile error is controlled within a preset tolerance range, and obtain a blade profile qualified model;

[0032] The root fillet smoothing processing module is configured to: adjust the cutting order of the root fillet processing tool path from both ends to the middle, process the root fillet area of ​​the blade contour qualified model, and obtain an impeller finished product with a smooth transition between the root fillet and the hub and blades.

[0033] The present invention also provides a numerically controlled machine tool, which performs milling processing on an impeller to be processed by using the large-diameter impeller processing method.

[0034] The present invention also provides a computer storage medium storing a computer software product. The computer software product includes several instructions for enabling a computer device to execute the method for processing a large-diameter impeller.

[0035] The above technical solution of the present invention has the following advantages over the prior art:

[0036] First, the present invention adopts a layer milling strategy combined with a fixed rotating axis to lock the tool posture, which greatly improves the rigidity of the tool, supports higher cutting parameters, quickly removes 80%-90% of excess material, evenly retains rough machining allowances, improves efficiency while reducing dependence on machine tool performance.

[0037] Second, the semi-finishing and finishing strategies are integrated. In the semi-finishing stage, the rigidity is enhanced by milling along the blade basin / back and retaining the allowance of the lower half of the blade profile. In the finishing stage, five-axis linkage milling is used and the processing sequence is optimized to effectively solve the problems of vibration marks and contour deviation of thin-walled blades.

[0038] Third, by cutting from both ends to the middle, combined with precise tool parameter settings and real-time monitoring and adjustment, a smooth transition between the root fillet and the hub and blades can be achieved, meeting stringent curvature continuity requirements and reducing the problem of uneven transition caused by tool installation errors and part deformation.

[0039] Fourth, introduce three-coordinate measurement or on-machine inspection, correct local tool paths in real time based on inspection data, dynamically adjust machining parameters through variable allowance compensation function, form a closed-loop feedback mechanism, and further improve machining accuracy and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0041] Figure 1 1 is a schematic flow chart of a method for processing a large-diameter impeller provided in an embodiment of the present invention;

[0042] Figure 2 1 is a schematic structural diagram of a large-diameter impeller processing system provided in an embodiment of the present invention;

[0043] Explanation of the reference numerals in the specification: 100, pre-processing and blank preparation module; 200, cavity rough processing module; 300, combined milling and blade forming module; 400, contour detection and variable allowance correction module; 500, root fillet smoothing processing module. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0045] Example 1:

[0046] like Figure 1 As shown, the present invention provides a method for processing a large-diameter impeller, the method comprising the following steps:

[0047] Step 1: Based on the actual geometric parameters of the impeller blade tip to be processed, a pre-milling blank model is constructed. This model is compared with the target impeller processing model that meets the requirements of milling processing, and the material area to be removed from the blank is determined to obtain the pre-processed blank model.

[0048] Step 2: Considering the gaps between the blades as slots, the pre-processed blank model is roughened using a layer milling type tool path to remove the material between the blades, leaving only a uniform roughing allowance, and obtain a roughing residual model;

[0049] Step 3: The rough machining residual model is subjected to allowance homogenization and forming processing by adopting a semi-finishing and finishing fusion method to obtain an impeller finishing product;

[0050] Step 4: performing local tool path correction processing on the impeller precision-machined product based on the detection data, so that the blade profile error is controlled within a preset tolerance range, and a blade profile qualified model is obtained;

[0051] Step 5: By adjusting the cutting sequence of the root fillet processing tool path from both ends to the middle, the root fillet area of ​​the blade contour qualified model is processed to obtain an impeller finished product with a smooth transition between the root fillet and the hub and blades.

[0052] As can be seen from the above technical solutions, the present invention systematically solves the existing difficulties in large-diameter impeller machining through process innovation, strategy optimization, and multi-link collaboration, as follows:

[0053] Treating the gaps between blades as slots, a layered milling cutter path is used, with the tool position locked by the machine's fixed rotary axis, significantly improving tool rigidity. This allows for higher cutting parameters, quickly removing 80%-90% of the material between blades, significantly improving machining efficiency compared to traditional layer milling strategies.

[0054] A method that integrates semi-finishing and finishing is adopted. In the semi-finishing stage, the blade disk layer milling roughing strategy is used to remove uneven allowances along the blade base and blade back, while retaining the allowance of the lower half of the blade profile as support to enhance the blade rigidity. In the finishing stage, the blade finishing strategy is used to gradually remove the remaining residual material through five-axis linkage milling. The processing sequence is adjusted to machine the upper part of the blade profile first, further reducing the risk of chatter marks caused by the poor rigidity of the thin-wall structure and ensuring that the blade profile error is controlled within the preset tolerance range.

[0055] The cutting sequence is from both ends to the middle, and the processing direction is selected from the hub to the blade or from the blade to the hub. The allowance is removed step by step with the preset cutting depth to avoid tool clamping and tool breakage caused by excessive cutting at one time, ensuring a stable processing process.

[0056] Specifically, in step 1, a pre-milling model is constructed based on the actual geometric parameters of the impeller blade tip to be machined, including the cylindrical base and redundant materials such as the blade tip and leading edge. The pre-milling model and the target impeller machining model are imported into the QJCAM programming software. The model comparison module performs 3D data difference analysis to accurately identify areas that need to be removed, such as the blade tip flare area and redundant leading edge material.

[0057] Based on the blade tip profile, CNC machining equipment is used to pre-cut the blank, removing unnecessary material to form a pre-processed blank model. This pre-machining process effectively reduces the cutting allowance in the subsequent roughing stage, reduces the cutting load on the tool, lays the foundation for efficient roughing, and simultaneously improves tool life and machining efficiency.

[0058] Furthermore, in this embodiment, in step 2, the method for obtaining the rough machining residual model includes:

[0059] The gaps between blades are treated as slots, and roughing is performed using a layer milling toolpath. The material removal process between blades is broken down into multiple cutting layers. Machining is performed using a fixed axis on a five-axis machine tool. During machining, two axes (such as the B and C axes or the A and C axes) are simultaneously fixed to lock the tool posture, creating a rigid cutting system that supports the application of high-load cutting parameters. Specific parameter configurations include: a feed rate range of 800 to 1200 mm / min, and a single-layer cutting depth of 5 to 10 mm.

[0060] During machining, the tool reciprocates along the inter-layer trajectory with the entire bottom surface participating in the cutting, reducing tool wear by uniformly distributing cutting forces. This process achieves efficient removal of 80% to 90% of the material between blades through a layered cutting pattern, ultimately leaving a uniform roughing allowance of 2 to 3 mm on each side of the blade surface. This ensures uniformity in material thickness between the machined surface and the impeller target model, forming a roughing residual model with a preliminary blade profile. This method significantly improves the efficiency of large-allowance material removal and machining stability by combining fixed-axis rigid support with efficient layer milling.

[0061] Furthermore, in an embodiment, in step 3, the method for obtaining the impeller finished product includes:

[0062] Using the QJCAM software's blisk layer milling roughing module, five-axis CNC machining is employed to perform contour milling along the blade basin and blade back profiles on both sides of a single flow channel, with the cutting path aligned with the tangent direction of the blade profile. This process removes the uneven stock remaining after roughing through layer milling, evenly balancing the blade surface stock to a range of 0.5 to 1 mm. A 0.3 to 0.5 mm process support allowance is retained in the lower half of the blade profile, particularly to create a rigid reinforcement structure in the thin-walled area of ​​the blade tip, thereby constructing a uniform semi-finishing allowance model.

[0063] Based on the uniform semi-finishing allowance model, the blade finishing strategy is called to perform five-axis linkage milling. The tool performs spiral interpolation motion along the theoretical surface trajectory of the blade to remove the remaining machining allowance layer by layer. The processing sequence is optimized by combining milling processes, and a "first up and then down" cutting path is adopted (that is, the upper 2 / 3 area of ​​the blade is processed first, and the support allowance of the lower half is retained). The tool lift detection node is preset in the processing program, the tool wear status is monitored in real time, and the tool is automatically changed as needed to ensure that the surface roughness value of the blade is controlled at Ra≤3.2μm and the blade profile error is ≤±0.05mm. Finally, through the integration of the above processes, an impeller finishing product that meets the requirements of precision machining is formed.

[0064] Furthermore, in step 4, the method for obtaining a qualified blade profile model includes:

[0065] Use a three-dimensional coordinate measuring machine or an on-machine detection system to collect global profile data of the impeller precision-machined product obtained in step 3. By comparing and analyzing it with the theoretical digital model, identify the local out-of-tolerance areas (e.g., a positive deviation of +0.1mm at the blade tip and a negative deviation of -0.08mm in the middle of the blade) and deformation patterns caused by factors such as tool overhang effect and elastic deformation of the machine tool structure.

[0066] Based on the local deviation area and deformation law, the variable allowance machining module is called in the QJCAM software to make advance compensation adjustments to the subsequent impeller finishing tool path, and the compensation value is directly integrated into the finishing tool path trajectory: for the positive deviation area (such as +0.1mm), a negative offset (-0.1mm) is applied to drive the tool to offset to the inside of the part to correct the contour; for the negative deviation area, reverse compensation is performed. At the same time, the cross-section dynamic control parameters (upper difference +0.05mm / lower difference -0.05mm) are configured to construct an adaptive cutting boundary. Through the above parametric adjustment, the optimized finishing tool path trajectory is generated;

[0067] The optimized finishing toolpath is then used to perform a subsequent finishing operation on the impeller. During this process, the system automatically controls the profile error within a precise tolerance of ±0.03mm, achieving the goal of precision manufacturing without manual polishing. Ultimately, a qualified blade profile model that meets design requirements is obtained, avoiding the costly secondary cutting of the same impeller. This technical solution, through a closed-loop detection and compensation mechanism, effectively addresses the profile tolerance issue caused by elastic deformation of the process system, significantly improving the manufacturing accuracy of the blade profile.

[0068] Furthermore, in this embodiment, in step 5, the method for obtaining the finished impeller with the root fillet smoothly connected to the hub and blades includes:

[0069] Adopting the root fillet finishing strategy dedicated to QJCAM software, the tool is milled along the root fillet and the milling path is planned. The single-direction processing method of hub→blade or blade→hub is selected, and the cutting sequence is optimized to convergent cutting from both ends to the middle. That is, the processing from the hub to the blade is carried out first, and then the cutting from the blade to the hub is carried out. Finally, the tool path connection is completed in the middle area. The single-tool cutting depth is controlled in the range of 0.2-0.5mm to avoid the risk of tool clamping during the cutting process. In order to remove the allowance at the position of the blade twist angle and the flow channel angle, a layered progressive cutting method is adopted to ensure processing stability.

[0070] In terms of process parameter setting, the tool radius on the blade side and the hub side is uniformly set to 15mm. To suppress the impact of cutting force fluctuations on the accuracy of the fillet contour, the down milling processing mode is selected and matched with a feed speed range of 300-500mm / min. Through the dynamic parameter configuration function of the QJCAM software, the tool axis inclination angle, feed rate and the number of additional deceleration tool paths at the corners are accurately set to achieve automatic deceleration control of the tool in the corner area. Combined with variable allowance compensation technology, a process compensation amount of 0.1mm is reserved in the fillet area for subsequent error correction;

[0071] In the process control and detection link, the virtual machine tool simulation module of QJCAM software is used to conduct real-time dynamic monitoring of the tool path trajectory, focusing on checking the curvature continuity of the fillet connection area. After processing is completed, a three-coordinate measuring machine is used to perform high-precision contour detection on the fillet transition area. If the test results show that there is a sudden change in curvature or a profile deviation, the variable allowance compensation function of QJCAM is immediately enabled to perform secondary optimization adjustment of the tool path. Through the closed-loop feedback correction mechanism, G2 continuity (curvature continuity) is ensured between the root fillet area and the hub and blade profiles. Ultimately, the profile error is strictly controlled within the precision tolerance range of ±0.03mm, achieving the smooth transition quality requirements of the root fillet area, and obtaining a finished impeller with a smooth transition between the root fillet and the hub and blades.

[0072] Example 2:

[0073] Based on the same inventive concept as that of the first embodiment, the present invention also provides a processing system for a large diameter impeller. Figure 2 As shown, the large diameter impeller processing system includes: a pre-processing and blank preparation module 100, a cavity rough processing module 200, a combined milling and blade forming module 300, a contour detection and variable allowance correction module 400 and a root fillet smoothing processing module 500; wherein,

[0074] The pre-processing and blank preparation module 100 is configured to: construct a pre-milling blank model based on the actual geometric parameters of the impeller blade tip to be processed, compare it with the target impeller processing model that meets the milling processing requirements, determine the material area to be removed from the blank, and obtain a pre-processed blank model;

[0075] The cavity rough machining module 200 is configured to: consider the gaps between the blades as slots, roughen the pre-processed blank model using a layer milling type tool path, remove the material between the blades, and retain only a uniform rough machining allowance to obtain a rough machining residual model;

[0076] The combined milling and blade shaping module 300 is configured to: perform a residual homogenization process and a shaping process on the roughing residual model using a semi-finishing and finishing fusion method to obtain a finished impeller product;

[0077] The contour detection and variable allowance correction module 400 is configured to: perform local tool path correction processing on the impeller precision-machined product based on the detection data, so that the blade profile error is controlled within a preset tolerance range, and obtain a blade profile qualified model;

[0078] The root fillet smoothing processing module 500 is configured to: adjust the cutting order of the root fillet processing tool path from both ends to the middle, and process the root fillet area of ​​the blade contour qualified model to obtain an impeller finished product with a smooth transition between the root fillet and the hub and blades.

[0079] A large-diameter impeller processing system proposed in this embodiment is used to implement the aforementioned large-diameter impeller processing method. Therefore, the specific implementation methods of the large-diameter impeller processing system can be seen in the embodiment part of the aforementioned large-diameter impeller processing method. For example, the pretreatment and blank preparation module 100, the cavity rough processing module 200, the combined milling and blade forming module 300, the contour detection and variable allowance correction module 400 and the root fillet smoothing processing module 500 are respectively used to implement the corresponding steps S1, S2, S3, S4 and S5 in the large-diameter impeller processing method in Example 1. Therefore, its specific implementation methods can refer to the descriptions of the corresponding embodiments of each part. In order to avoid redundancy, they will not be repeated here.

[0080] Example 3:

[0081] The present invention also provides a CNC machine tool for performing milling processing on an impeller to be processed using the processing method for a large-diameter impeller described in the first embodiment.

[0082] Specifically, the CNC machine tool includes a five-axis machining platform, a spindle system, an intelligent tool management system, and an in-machine detection system. The five-axis machining platform utilizes a dual-turntable or swing-head-turntable configuration, offering B / C-axis rotation accuracy ≤±2, X / Y / Z-axis positioning accuracy ≤±0.005mm, and repeatability ≤±0.003mm, meeting the multi-axis machining requirements for complex curved surfaces on large-diameter impellers.

[0083] The spindle system is equipped with a 20,000 rpm electric spindle with an output torque ≥100 Nm. It uses liquid hydrostatic bearing or magnetic levitation bearing technology to suppress cutting vibration and ensure processing stability in the thin-wall area of ​​the blade tip.

[0084] The intelligent tool management system is equipped with more than one tool magazine, integrates tool breakage detection, life management, and automatic tool setting functions, and supports the tool change strategy of the tool lifting node preset by the QJCAM software.

[0085] The on-machine detection system has a built-in trigger probe or laser scanning probe to realize real-time dimensional detection during the processing process, with a detection accuracy of ≤±0.005mm, providing data support for the variable allowance compensation in step 4 of the large-diameter impeller processing method.

[0086] Example 4:

[0087] The present invention also provides a computer storage medium storing a computer software product. The computer software product includes several instructions for enabling a computer device to execute the large-diameter impeller processing method described in Example 1.

[0088] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0089] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0090] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0091] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0092] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for processing a large diameter impeller, characterized in that: The following steps are involved: Step 1: Based on the actual geometric parameters of the impeller blade tip to be processed, a pre-milling blank model is constructed. This model is compared with the target impeller processing model that meets the requirements of milling processing, and the material area to be removed from the blank is determined to obtain the pre-processed blank model. Step 2: Considering the gaps between the blades as slots, the pre-processed blank model is roughened using a layer milling type tool path to remove the material between the blades, leaving only a uniform roughing allowance, and obtain a roughing residual model; Step 3: The rough machining residual model is subjected to allowance homogenization and forming processing by adopting a semi-finishing and finishing fusion method to obtain an impeller finishing product; Step 4: performing local tool path correction processing on the impeller precision-machined product based on the detection data, so that the blade profile error is controlled within a preset tolerance range, and a blade profile qualified model is obtained; Step 5: By adjusting the cutting sequence of the root fillet processing tool path from both ends to the middle, the root fillet area of ​​the blade contour qualified model is processed to obtain an impeller finished product with a smooth transition between the root fillet and the hub and blades.

2. The method for processing a large-diameter impeller according to claim 1, characterized in that: In step 2, the method for obtaining the rough machining residual model includes: The gaps between the blades are regarded as slots, and roughing is performed using a layer milling type tool path. The material removal process between the blades is decomposed into multiple cutting layers. The tool posture is locked by the fixed rotating axis of the machine tool, and the cutting parameters of the tool are adjusted. Each layer is cut back and forth along the inter-layer trajectory using the entire bottom surface of the tool according to the set cutting parameters, removing 80% to 90% of the material between the blades and retaining only a uniform roughing allowance, that is, the material thickness between the blade surface and the impeller target processing model is uniform, forming a preliminary blade contour and obtaining a roughing residual model.

3. The method for processing a large-diameter impeller according to claim 2, characterized in that: The cutting parameters include feed rate and cutting depth.

4. The method for processing a large diameter impeller according to claim 1, characterized in that: In step 3, the method for obtaining the impeller finished product includes: Through the blade disk layer milling roughing strategy, a five-axis linkage cutting method is adopted to mill the blade basin and blade back along the left and right sides of a single flow channel. The cutting direction is consistent with the blade profile line. The uneven allowance remaining after roughing is removed, and the blade surface allowance is uniformed within the preset processing range. The allowance of the lower half of the blade profile is retained. The blade rigidity is enhanced by the allowance support, forming a semi-finishing allowance uniform model. Based on the uniform semi-finishing allowance model, the blade finishing strategy is utilized, and through five-axis linkage milling, the tool moves along the blade surface trajectory, gradually removing all the remaining residual materials after semi-finishing. The machining sequence is adjusted through the combined milling strategy to finally form the impeller finishing product.

5. The method for processing a large diameter impeller according to claim 1, characterized in that: In step 4, the method for obtaining a qualified blade profile model includes: Obtain the contour data of the impeller precision-machined product through three-dimensional coordinate measurement or on-machine testing, and identify the local out-of-tolerance areas and deformation patterns caused by factors including tool overhang and machine tool yield; Based on the local tolerance area and deformation law, the subsequent impeller finishing tool path is compensated and adjusted in advance, and the compensation value is directly integrated into the finishing tool path trajectory to generate an optimized finishing tool path trajectory; The subsequent impeller is fine-machined once using the optimized fine-machining tool path trajectory, so that the blade profile error is controlled within a preset tolerance range, and a qualified blade profile model is obtained.

6. The method for machining a large diameter impeller according to claim 1, characterized in that: In step 5, the method for obtaining the finished impeller with the root fillet and the hub and blades smoothly connected includes: Using the root fillet finishing strategy, the tool mills around the root fillet, selecting one of the machining directions: from the hub to the blade or from the blade to the hub. By adjusting the cutting sequence to cut from both ends to the middle, the allowance at the angle between the blade profile twist angle and the flow channel is gradually removed at the preset cutting depth. At the same time, the allowance of the fillet area is adjusted according to the processing requirements to ensure that the curvature of the root fillet processing area and the hub and blade profiles are continuous and without sudden changes, so as to obtain an impeller product with a smooth transition between the root fillet and the hub and blades.

7. The method for machining a large-diameter impeller according to claim 6, characterized in that: Methods for adjusting the allowance of the fillet area according to processing requirements to ensure that the curvature of the root fillet processing area and the hub and blade profiles are continuous and without sudden changes include: Define the blade and hub tool radius, select the down milling mode, set the tool axis angle, feed rate, and number of corner extra deceleration toolpaths; During the machining process, the tool path trajectory is monitored and the curvature continuity of the fillet joint is checked. After machining, the contour of the fillet transition area is detected using a three-coordinate measuring machine. If a sudden change or deviation is found, the tool path is adjusted again using the variable allowance function until the tolerance control requirements for the smooth transition between the root fillet and the hub and blade are met.

8. A large diameter impeller processing system, characterized in that: The large diameter impeller processing system includes: pre-processing and blank preparation module, cavity rough processing module, combined milling and blade forming module, contour detection and variable allowance correction module and root fillet smoothing processing module; wherein, The pre-processing and blank preparation module is configured to: construct a pre-milling blank model based on the actual geometric parameters of the impeller blade tip to be processed, compare it with the target impeller processing model that meets the milling processing requirements, determine the material area to be removed from the blank, and obtain a pre-processed blank model; The cavity rough machining module is configured to: consider the gaps between the blades as slots, roughen the pre-processed blank model using a layer milling type tool path, remove the material between the blades, and retain only a uniform rough machining allowance to obtain a rough machining residual model; The combined milling and blade forming module is configured to: perform allowance homogenization and forming processing on the roughing residual model using a semi-finishing and finishing fusion method to obtain an impeller finishing product; The contour detection and variable allowance correction module is configured to: perform local tool path correction processing on the impeller precision-machined product based on the detection data, so that the blade profile error is controlled within a preset tolerance range, and obtain a blade profile qualified model; The root fillet smoothing processing module is configured to: adjust the cutting order of the root fillet processing tool path from both ends to the middle, process the root fillet area of ​​the blade contour qualified model, and obtain an impeller finished product with a smooth transition between the root fillet and the hub and blades.

9. A CNC machine tool, characterized in that: The impeller to be processed is milled by the method for processing a large-diameter impeller according to any one of claims 1 to 7.

10. A computer storage medium, characterized in that The computer storage medium stores a computer software product, and the computer software product includes a number of instructions for enabling a computer device to execute the method for processing a large-diameter impeller according to any one of claims 1 to 7.

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