Numerical control machining path optimization method for undercarriage shell machining

Abstract

The invention particularly relates to a numerical control machining path optimization method for undercarriage shell machining, and relates to the technical field of numerical control machining. Generating an initial processing path and setting parameters; adjusting parameters driven by a path optimization algorithm; and performing virtual simulation verification and path correction. According to the method, Dijkstra and genetic algorithms are used for optimizing the machining sequence and path, strategies such as equal residual height control are adopted for balancing the cutting load, and the optimal cutting parameters are solved through a multi-objective function. The relation among the machining time, the surface roughness and the tool abrasion loss is fully considered in the process, and collaborative optimization of the machining efficiency, the machining quality and the tool service life is achieved. And the problems of low machining efficiency, substandard surface quality, premature wear of the cutter and the like caused by unreasonable parameters are avoided, the production cost is effectively reduced, and the production benefit is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of numerical control machining, and in particular to a method for optimizing a numerical control machining path for machining a landing gear shell. Background Art

[0002] During the CNC machining of landing gear shells, it is difficult to achieve a precise balance between machining efficiency, surface quality, and tool life. The lack of a unified and scientific mathematical model to quantify the combined impact of cutting parameters on machining time, surface roughness, and tool wear makes multi-objective optimization lack an effective basis and the cost of trial and error remains high.

[0003] From the perspective of quantitative prediction of the machining process, machining time estimation is crude. Traditional calculation methods do not fully consider tool path details (such as idle movement, feed and retract), as well as dynamic changes in cutting parameters (such as adjusting the depth of cut and feed rate based on the characteristics of the machining area). This leads to a large deviation between the planned time and the actual machining time, making it difficult to accurately control.

[0004] Surface roughness prediction relies on post-process testing. Traditional models ignore the complex effects of tool geometry and cutting motion parameters on the residual area, making it difficult to accurately predict before processing and increasing debugging costs.

[0005] Tool wear is judged solely by experience, without establishing a physical relationship between cutting heat (plastic deformation heat, friction heat) and wear. Therefore, tool life cannot be accurately predicted, leading to excessive wear affecting accuracy or premature replacement that wastes costs.

[0006] Therefore, a CNC machining path optimization method for landing gear shell machining is needed to address the above-mentioned problems. Summary of the Invention

[0007] The purpose of the present invention is to solve the above problems and to propose a method for optimizing the numerical control machining path of a landing gear shell.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for optimizing a numerical control machining path for a landing gear shell, comprising:

[0010] Part process characteristics analysis and processing planning: Analyze the landing gear housing's geometric structure and material characteristics, develop a layered process route based on this, and divide the processing strategy for each area;

[0011] Initial machining path generation and parameter setting: Generate the initial tool path, combine the machining process, material and part structure, preliminarily select the tool and set the cutting parameters;

[0012] Parameter adjustment driven by path optimization algorithm: Dijkstra is used to optimize the processing sequence and path, the equal stub height control strategy is used to balance the cutting load, and the optimal cutting parameters are solved through multi-objective functions;

[0013] Virtual simulation verification and path correction: Simulate the entire machining process based on simulation software, detect interference and overcutting problems, and iteratively correct tool paths and parameters based on simulation results.

[0014] Preferably, the part process characteristics analysis and processing planning specifically include:

[0015] Conduct a comprehensive analysis of the landing gear shell 3D model and obtain geometric parameters using model measurement tools;

[0016] In terms of material evaluation, considering the high plasticity of titanium alloys, the sticking phenomenon during cutting can be improved by adjusting the cutting fluid formula and tool coating. In view of the high hardness of high-strength steel, it is necessary to select appropriate tool materials and cutting processes.

[0017] When formulating a hierarchical process route for roughing, semi-finishing, and finishing, it is necessary to reasonably allocate the machining allowance of each process based on the material removal amount and precision requirements of the parts;

[0018] When dividing the processing area according to the features of the parts, the feasibility and efficiency of the processing technology should be taken into consideration.

[0019] Preferably, the initial processing path generation and parameter setting specifically include:

[0020] Import the 3D model of the landing gear housing into the software, perform model repair and simplification, and remove unnecessary details. For rough machining path generation, select the follow-part strategy and set the cutting layer, step length, and cutting direction parameters to achieve efficient material removal.

[0021] The generation of finishing paths requires strategic selection based on the surface curvature;

[0022] Tool selection requires comprehensive consideration of processing technology, material properties, and part structure; for rough machining, a large-diameter insert milling cutter is used; for fine machining, a small-diameter integral milling cutter is used to ensure accuracy;

[0023] When initially setting the cutting parameters, refer to the cutting parameter table provided by the tool supplier and make adjustments based on the material properties.

[0024] Preferably, the parameter adjustment driven by the path optimization algorithm specifically includes:

[0025] Use Dijkstra algorithm to optimize the processing sequence of each processing area, calculate the shortest path between each area based on the part coordinate system, and reduce the tool travel distance;

[0026] Adjust the step size by controlling the constant stub height. Set the stub height parameter in the CAM software, and the software will automatically adjust the step size according to the surface curvature.

[0027] A multi-objective optimization function including machining time T, surface roughness R, and tool wear V is established:

[0028] Where x represents the weight factor corresponding to the cutting parameters processing time, surface roughness, and tool wear; T′ is the preset standard processing time;

[0029] The multi-objective optimization function is solved to find the optimal combination of cutting parameters while meeting the machining accuracy requirements.

[0030] Preferably, the process of obtaining the processing time includes:

[0031] According to the motion trajectory and cutting parameters of the tool during the machining process, the time required for the tool to cut each area is obtained through geometric calculation, and then the time of each area is accumulated to obtain the machining time.

[0032] Preferably, the process of obtaining the surface roughness includes:

[0033] Tool parameters include tool tip radius r e , main deflection angle k r , secondary deflection angle k′ r , tool feed rate f;

[0034] The cutting motion includes the synthetic trajectory of cutting speed and feed rate;

[0035] When the tool is a sharp tool, the residual area is determined by the main deflection angle and the secondary deflection angle. The calculation formula for the residual area and the residual area height is:

[0036] When the tool has a tool nose arc radius r e When , the residual area height can be approximated as:

[0037] A height threshold is preset, and the height of the residual area above the height threshold is recorded as the roughness height;

[0038] Obtain all roughness heights corresponding to the residual material after tool cutting, and count all the roughness heights to obtain the total roughness height;

[0039] Based on the tool's travel path, the total travel length of the tool is obtained; the total roughness height is divided by the total travel length of the tool to obtain the unit length roughness; a unit length roughness threshold is preset, and the unit length roughness is divided by the unit length roughness threshold to obtain the surface roughness.

[0040] Preferably, the process of obtaining the tool wear amount includes:

[0041] Calculate the heat of plastic deformation:

[0042] Where σ is the equivalent stress on the workpiece material in the cutting area;

[0043] ε is the equivalent strain of the workpiece material in the cutting zone;

[0044] is the equivalent strain rate; η is the proportional coefficient of plastic work converted into heat energy;

[0045] Calculate friction heat: Q fricition =μ·F·v c ;

[0046] μ is the coefficient of friction;

[0047] F is the normal contact force at the tool-chip and tool-workpiece contact interfaces;

[0048] v c is the cutting speed;

[0049] Correlating the plastic deformation heat with the friction heat, we get the thermal correlation: Fx = ∫ 接触区 σ·dA∝Q plastic +Q friction ;

[0050] where ∫ 接触区 σ·dA is the stress integral of the contact area, σ is the normal stress in the contact area, and dA is the infinitesimal area of ​​the contact area;

[0051] Based on the fact that the tool hardness H is a function of the temperature T, the hardness temperature function is obtained: T = f (Q plastic ,Q friction );

[0052] Substituting the thermal correlation and hardness temperature function into the formula:

[0053] Where K is the wear coefficient; is the initial normal force; k1 is the thermal coefficient; H0 is the room temperature hardness; α is the thermal softening coefficient;

[0054] The subsequent entry formula: Get the tool wear; where h c is the initial wear amount.

[0055] Preferably, the virtual simulation verification and path correction specifically include:

[0056] Using CNC machining simulation software, import optimized tool paths, machine tool models, fixture models, and part blank models to perform virtual machining of the entire process;

[0057] The collision detection function of the simulation software can be used to check the interference and collision between the tool and the fixture and machine tool in real time. At the same time, the cutting analysis function of the software can be used to detect overcutting and undercutting during the cutting process, observe the distribution of cutting force and cutting heat, and predict the deformation of thin-walled areas through finite element coupling simulation.

[0058] Preferably, the physical processing verification and process solidification: carry out first-piece trial processing, collect processing data to evaluate the optimization effect, organize the final optimization plan into a standardized process document, and establish an enterprise processing knowledge base.

[0059] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0060] 1. This invention optimizes the machining sequence and path using Dijkstra and genetic algorithms, balances the cutting load using strategies such as constant residual height control, and solves for optimal cutting parameters using a multi-objective function. This process fully considers the relationship between machining time, surface roughness, and tool wear, achieving a coordinated optimization of machining efficiency, quality, and tool life. This avoids problems such as low machining efficiency, substandard surface quality, and premature tool wear caused by inappropriate parameters, effectively reducing production costs and improving production efficiency.

[0061] 2. This invention utilizes professional CNC machining simulation software to perform virtual machining of the entire process. Utilizing collision detection and cutting analysis, it can proactively detect interference and collisions between the tool and fixture, as well as between the machine tool and overcutting and undercutting during the cutting process. It also predicts deformation in thin-walled areas through finite element coupled simulation. Iteratively correcting tool paths and parameters based on simulation results can effectively avoid safety incidents and quality issues in actual machining, reduce trial-and-error costs, improve machining success rates, and ensure a safe, stable, and high-quality machining process. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Further details, features and advantages of the present application are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which:

[0063] Figure 1 This is a structural diagram of the method of the present invention. DETAILED DESCRIPTION

[0064] Several embodiments of the present application will be described in more detail below with reference to the accompanying drawings so that those skilled in the art can implement the present application. The present application can be embodied in many different forms and for many different purposes and should not be limited to the embodiments described herein. These embodiments are provided to make the present application comprehensive and complete and to fully convey the scope of the present application to those skilled in the art. The embodiments do not limit the present application.

[0065] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the relevant art and / or the context of this specification, and will not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein.

[0066] Example 1

[0067] The specific implementation method is combined with the attached Figure 1 Provide detailed explanation.

[0068] Attachment Figure 1 A structural block diagram of a CNC machining path optimization method for landing gear shell machining provided by an embodiment of the present invention shows the complete steps from part process characteristic analysis and machining planning to physical machining verification and process solidification.

[0069] In this embodiment, it includes:

[0070] Part process characteristics analysis and processing planning: CAD / CAM software is used to analyze the landing gear housing's geometric structure and material characteristics, based on which a hierarchical process route is developed and processing strategies are divided into different areas;

[0071] Specifically include:

[0072] A comprehensive analysis of the landing gear shell's 3D model was performed using CAD / CAM software. Model measurement tools were used to determine geometric parameters such as the wall thickness distribution of thin-walled structures, the depth-to-diameter ratio of deep cavities, and the curvature variation of complex curved surfaces. For thin-walled structures, the critical wall thickness (typically ≤3mm) was emphasized, and deformation trends under cutting forces were analyzed. For deep-cavity structures, the depth-to-diameter ratio (>5) was evaluated to determine tool accessibility and machining stability. The positional accuracy (tolerance requirement ≤0.05mm) and cylindricity requirements of high-precision hole systems required detailed analysis based on subsequent assembly requirements.

[0073] In terms of material evaluation, the high plasticity of titanium alloys (such as 7075) and the tool sticking phenomenon during cutting should be considered and improved by adjusting the cutting fluid formula and tool coating. Titanium alloys (such as TC4) have poor thermal conductivity (the thermal conductivity coefficient is only 1 / 4 of that of steel), which easily leads to high-temperature wear of the tool. Special titanium alloy milling cutters should be used, and cutting parameters should be optimized, such as reducing the cutting speed to avoid tool failure due to overheating. The high hardness of high-strength steel places higher requirements on the wear resistance and toughness of the tool, requiring the selection of appropriate tool materials (such as carbide-coated tools) and cutting processes.

[0074] When developing a hierarchical process route for roughing, semi-finishing, and finishing, it is necessary to reasonably allocate the machining allowances for each process based on the material removal volume and precision requirements of the parts. In the roughing stage, a large cutting depth and high feed rate are used to quickly remove more than 80% of the allowance, with insert face milling cutters or corn milling cutters being preferred to improve material removal efficiency. In semi-finishing, a machining allowance of 0.5 to 1 mm is reserved to create a good foundation for finishing, while also performing preliminary shaping on key parts. Finishing aims to ensure final accuracy, strictly controlling cutting parameters to ensure that dimensional accuracy and surface quality meet standards.

[0075] When dividing the processing areas according to part features, the feasibility and efficiency of the processing technology are taken into consideration. For the top flat area, an end mill is used for line cutting or circular cutting, utilizing the side edge of the tool for processing to ensure flatness. Due to space limitations, the side cavity area is milled in layers using a long-edge end mill. The layer thickness is determined based on the tool overhang length and cutting force, and generally does not exceed 1 / 3 of the tool diameter. The processing of the hole system area follows the process of center drill positioning, drilling, reaming, and boring. The center drill positioning accuracy directly affects the position accuracy of subsequent holes. The feed speed must be controlled during drilling to avoid drill breakage. When reaming or boring, the cutting parameters must be strictly controlled to ensure the dimensional accuracy and surface roughness of the hole.

[0076] Initial machining path generation and parameter setting: Generate the initial tool path through CAM software, combine the machining process, material and part structure, preliminarily select the tool and set the cutting parameters;

[0077] Specifically include:

[0078] Import the 3D model of the landing gear housing into CAM software such as UG, CATIA, or Mastercam, perform model repair and simplification, remove unnecessary details, and improve programming efficiency. For roughing path generation, select the follow-part or cavity milling strategy. Set the cutting layer, stepover, and cutting direction parameters to achieve efficient material removal. When setting the stepover, adjust it based on the tool diameter and material properties to ensure a balance between cutting efficiency and tool life.

[0079] Finishing path generation requires strategic selection based on the surface curvature. For surfaces with small curvature variations, contour milling is used, ensuring uniform machining allowances by setting a constant cutting depth. For complex surfaces with large curvature variations, streamline milling is used, allowing the tool path to follow the streamline direction of the surface, ensuring the fit between the tool and the surface and improving surface machining quality. At the same time, during the programming process, safe heights and avoidance zones must be properly set to prevent collisions between the tool and fixtures or machine tools.

[0080] Tool selection requires comprehensive consideration of processing technology, material properties, and part structure. For rough machining, large-diameter insert milling cutters (such as Φ25mm) are used to improve efficiency. Insert milling cutters can replace blades according to wear conditions, reducing tool costs. For fine machining, small-diameter integral milling cutters (such as Φ10mm ball-end cutters) are used to ensure accuracy. Ball-end cutters are better suited to machining complex curved surfaces.

[0081] When initially setting cutting parameters, refer to the cutting parameter table provided by the tool supplier and adjust them in combination with the material characteristics; the roughing speed is generally set at 1000-1500r / min, the feed rate is 1000-1500mm / min, and the cutting depth is determined according to the tool and machine tool performance, generally not exceeding 1 / 2 of the tool diameter; the finishing speed is increased to 2000-3000r / min, the feed rate is 500-800mm / min, and the cutting depth is controlled at 0.2-0.5mm to ensure surface quality. In actual processing, the cutting parameters need to be fine-tuned according to the vibration and cutting sound during the cutting process;

[0082] Parameter adjustment driven by path optimization algorithm: Dijkstra and genetic algorithms are used to optimize the processing sequence and path, the equal residual height control strategy is used to balance the cutting load, and the optimal cutting parameters are solved through multi-objective functions;

[0083] Specifically include:

[0084] Use Dijkstra algorithm or genetic algorithm to optimize the processing sequence of each processing area. Based on the part coordinate system, calculate the shortest path between each area to reduce the tool travel distance. During the optimization process, consider the tool change position and the kinematic characteristics of the machine tool to avoid unnecessary lifting and turning of the tool during the idle travel.

[0085] When optimizing the tool entry and exit method, use a 45° oblique cut or arc cut. The oblique cut angle and arc radius need to be adjusted according to the tool diameter and cutting parameters. Generally, the oblique cut angle does not exceed 15°, and the arc radius is 1 to 1.5 times the tool diameter. This cut method can effectively reduce the impact of the tool during cutting, reduce cutting vibration, and avoid leaving tool marks on the part surface.

[0086] Adjust the stepover distance by controlling the constant stub height. Set the stub height parameter in the CAM software, and the software will automatically adjust the stepover distance based on the surface curvature. In steep areas of the surface, the stepover distance will be reduced accordingly to ensure a uniform stub; in flat areas, the stepover distance will be appropriately increased to improve processing efficiency. At the corners of the path, add a 0.5-1mm arc transition and reduce the feed speed to 60%-80% of the normal speed to reduce the impact of centrifugal force on the tool and prevent tool deflection and increased wear.

[0087] For thin-walled areas, spiral milling or trochoidal milling strategies are used. By controlling the spiral radius and trochoidal radius of the tool, the cutting force is evenly distributed on the thin-wall structure, reducing radial force concentration. In spiral milling, the spiral radius is generally 0.5 to 1 times the tool diameter, and the trochoidal radius of trochoidal milling is adjusted according to the cutting depth and feed rate. Deep cavity processing adopts a combination of layered and spiral cutting. The cutting angle is ≤5°, and the cutting depth of each layer does not exceed 1 / 3 of the tool diameter. This ensures that the tool cuts into the material smoothly and avoids tool damage and cutting vibration caused by vertical cutting.

[0088] A multi-objective optimization function including machining time T, surface roughness R, and tool wear V is established:

[0089] Where x represents the cutting parameters (speed, feed rate, cutting depth, etc.); a1, a2, and a3 are the weight factors corresponding to machining time, surface roughness, and tool wear, respectively; T′ is the preset standard machining time;

[0090] The response surface method or genetic algorithm is used to solve the multi-objective optimization function and find the optimal combination of cutting parameters while meeting the machining accuracy requirements. The response surface method analyzes the relationship between cutting parameters and objective functions by constructing a response surface model, while the genetic algorithm searches for the optimal solution in the parameter space by simulating the natural evolution process. In practical applications, the advantages of both methods can be combined to improve optimization efficiency and accuracy.

[0091] The process of obtaining surface roughness includes:

[0092] Based on the geometric motion trajectory of the tool and workpiece during the cutting process, assuming that the cutting process is in an ideal state (no vibration, no tool wear, and sufficient material rigidity), the residual area height is deduced through the geometric relationship, and then the surface roughness is calculated;

[0093] Tool parameters include tool tip radius r e , main deflection angle k r , secondary deflection angle k′ r , tool feed rate f;

[0094] The cutting motion includes the synthetic trajectory of cutting speed and feed rate;

[0095] When the tool is a sharp tool (the radius of the tool tip arc is 0), the residual area is determined by the main deflection angle and the secondary deflection angle. The calculation formula for the residual area and the residual area height is:

[0096] When the tool has a tool nose arc radius r e When , the residual area height can be approximated as: That is, when the tool feed rate f is much smaller than the arc radius, the residual area can be regarded as the chord height of the arc segment;

[0097] A height threshold is preset, and the height of the residual area above the height threshold is recorded as the roughness height;

[0098] Obtain all roughness heights corresponding to the residual material after tool cutting, and count all the roughness heights to obtain the total roughness height;

[0099] Based on the tool's travel path, the total travel length of the tool is obtained; the total roughness height is divided by the total travel length of the tool to obtain the unit length roughness; a unit length roughness threshold is preset, and the unit length roughness is divided by the unit length roughness threshold to obtain the surface roughness;

[0100] The process of obtaining processing time includes:

[0101] According to the tool's motion trajectory and cutting parameters during the machining process, the time required for the tool to cut each area is calculated through geometric calculation, and then the time of each area is accumulated to obtain the machining time;

[0102] The process of obtaining tool wear includes:

[0103] The finite element method is used to couple the heat conduction (temperature field) and mechanical analysis (stress field) during the cutting process to simulate the wear mechanism of the tool under high temperature and high pressure;

[0104] During the cutting process, cutting heat (plastic deformation, friction) and cutting force (mechanical load) act together in the contact area between the tool and the workpiece, forming a coupled effect of temperature field and stress field. High temperature will reduce the hardness of the tool material, and stress concentration will aggravate material fatigue. The two synergistically lead to tool wear;

[0105] The tool and workpiece are discretized into a finite number of units, and the temperature and stress distribution of each unit are calculated by numerically solving the heat conduction equation and the mechanical equilibrium equation. The wear amount is then predicted by combining the wear model.

[0106] Use CAD software to build a 3D model of the tool (such as a turning tool or milling cutter) and the workpiece, focusing on the geometric details near the cutting edge (such as the cutting edge radius and back angle), and mesh the contact area.

[0107] Determine the thermal conductivity, specific heat capacity, and thermal expansion coefficient of the tool material;

[0108] Plastic deformation heat generation rate and heat conduction characteristics of the workpiece material;

[0109] Calculate the heat of plastic deformation:

[0110] Where σ is the equivalent stress on the workpiece material in the cutting zone; it is an indicator that comprehensively reflects the mechanical response of the material under complex stress conditions, with the unit being Pa (Pascal); it reflects the material's ability to resist plastic deformation. During the cutting process, the material undergoes plastic flow in the cutting zone.

[0111] ε is the equivalent strain of the workpiece material in the cutting zone. It is dimensionless and describes the degree of plastic deformation of the material, reflecting the relative amount of shape change during the cutting process. For example, if the material originally has a regular shape, its shape changes after plastic deformation during cutting. ε quantifies this deformation and can also be obtained through constitutive models, cutting simulations, or experimental analysis.

[0112] It is the equivalent strain rate, which indicates the change in equivalent strain per unit time and reflects the speed of plastic deformation. During the cutting process, the tool cuts the workpiece quickly and the material undergoes plastic deformation in a very short time. The value is usually large and is closely related to cutting speed, tool geometry, etc. It can be calculated through cutting simulation or obtained indirectly through experimental means such as high-speed photography.

[0113] η is the proportional coefficient of plastic work converted to heat energy, dimensionless, and has a value of approximately 0.9 (i.e., about 90% of the plastic work will be converted into heat energy, and the rest will be used for changes in the internal structure of the material, etc.);

[0114] Calculate friction heat: Q friction =μ·F·v c ;

[0115] μ is the coefficient of friction;

[0116] F is the normal contact force at the tool-chip and tool-workpiece contact interfaces; it is the force perpendicular to the contact surface;

[0117] v c is the cutting speed, that is, the speed at which the cutting edge of the tool moves relative to the surface of the workpiece to be machined;

[0118] Correlating the plastic deformation heat with the friction heat, we get the thermal correlation: F v =∫ 接触区 σ·dA∝Q plastic +Q friction ;

[0119] where ∫ 接触区σ·dA is the stress integral of the contact area, σ is the normal stress in the contact area, and dA is the infinitesimal area of ​​the contact area;

[0120] Based on the fact that the tool hardness H is a function of temperature T, and the temperature T is determined by the plastic deformation heat and friction heat, the hardness temperature function is obtained: T = f (Q plastic ,Q friction );

[0121] Substituting the thermal correlation and hardness temperature function into the formula:

[0122] Where K is the wear coefficient; is the initial normal force; k1 is the thermal coefficient; H0 is the room temperature hardness; α is the thermal softening coefficient;

[0123] The subsequent entry formula: Get the tool wear; where h c is the initial wear amount;

[0124] Virtual simulation verification and path correction: Simulate the entire machining process based on simulation software, detect interference and overcutting problems, and iteratively correct tool paths and parameters based on simulation results;

[0125] Specifically include:

[0126] Use professional CNC machining simulation software such as VERICUT or NCSIMUL to import optimized tool paths, machine tool models, fixture models, and part blank models to perform virtual machining of the entire process. During the simulation, set the same cutting parameters and machine tool motion parameters as in actual machining to simulate a real machining environment.

[0127] The collision detection function of the simulation software can be used to check the interference and collision between the tool, fixture, and machine tool in real time. Once a collision is detected, the simulation is immediately stopped to analyze the cause of the collision and adjust the tool path or fixture layout. At the same time, the cutting analysis function of the software can be used to detect overcutting and undercutting during the cutting process, observe the distribution of cutting force and cutting heat, and predict the deformation of thin-walled areas through finite element coupling simulation to provide a basis for path correction.

[0128] Analyze the problems found based on the simulation results. For example, if the peak cutting force exceeds the allowable tool load, re-evaluate the cutting parameters, appropriately reduce the cutting depth or feed rate, or replace a more wear-resistant tool. When the vibration amplitude of deep cavity machining is greater than 0.02mm, optimize the cutting path, adjust the layer thickness and cutting angle, and increase the stability of the tool. Based on the analysis results, regenerate the local path, modify the relevant parameters in the CAM software, and perform simulation verification again until the simulation results meet the machining requirements. During the path iteration process, a step-by-step optimization method can be used, adjusting only one or a few key parameters each time and observing the changes in the simulation results to accurately find a solution to the problem and improve optimization efficiency.

[0129] Physical processing verification and process solidification: Conduct first-piece trial processing, collect processing data to evaluate optimization effects, organize the final optimization plan into standardized process documents, and establish an enterprise processing knowledge base;

[0130] Specifically, it involves first-piece machining on CNC machines, using the same machine model, tools, and materials as those used in actual production, and strictly following optimized process parameters and tool paths. During machining, a three-dimensional coordinate measuring machine is used to perform real-time inspections of key dimensions and record actual dimensional deviations during machining.

[0131] At the same time, data such as processing time, surface roughness, and tool wear are collected. Processing time is obtained using the machine tool's timing function, surface roughness is measured using a roughness meter, and tool wear is measured by observing the width of the tool's flank wear band under a microscope (flank wear band width ≤ 0.3mm is considered acceptable). Compare the processing data before and after optimization to evaluate the efficiency improvement and quality improvement;

[0132] The final optimized NC program, tool list, cutting parameter table, machining process route, etc. are organized into standardized process documents. The process documents should detail the machining content, machining parameters, tool model and clamping method of each process for reference in subsequent production;

[0133] Establish internal machining guidelines, summarize experience and techniques from the landing gear shell machining process, and develop a knowledge base including deep cavity machining path optimization templates and a thin-walled parts cutting parameter database. Apply these optimization methods and experience to the machining of similar parts, improving the company's overall machining level and production efficiency. Furthermore, continuously accumulate and improve the machining process knowledge system to support the company's technological innovation.

[0134] The above formulas are obtained by collecting a large amount of data for software simulation and selecting a formula that is close to the real value. The influencing weight factors and specific coefficient values ​​in the formulas are set by those skilled in the art according to actual conditions and can be adjusted and modified later. The above embodiments can be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer program are loaded or executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device.

Claims

1. A method for optimizing the CNC machining path of a landing gear shell, characterized in that: include: Part process characteristics analysis and processing planning: Analyze the landing gear housing's geometric structure and material characteristics, develop a layered process route based on this, and divide the processing strategy for each area; Initial machining path generation and parameter setting: Generate the initial tool path, combine the machining process, material and part structure, preliminarily select the tool and set the cutting parameters; Parameter adjustment driven by path optimization algorithm: Dijkstra is used to optimize the processing sequence and path, the equal stub height control strategy is used to balance the cutting load, and the optimal cutting parameters are solved through multi-objective functions; Virtual simulation verification and path correction: Simulate the entire machining process based on simulation software, detect interference and overcutting problems, and iteratively correct tool paths and parameters based on simulation results.

2. The method for optimizing the CNC machining path of a landing gear shell according to claim 1, characterized in that: Parts process characteristics analysis and processing planning, including: Conduct a comprehensive analysis of the landing gear shell 3D model and obtain geometric parameters using model measurement tools; In terms of material evaluation, considering the high plasticity of titanium alloys, the sticking phenomenon during cutting can be improved by adjusting the cutting fluid formula and tool coating. In view of the high hardness of high-strength steel, it is necessary to select appropriate tool materials and cutting processes. When formulating a hierarchical process route for roughing, semi-finishing, and finishing, it is necessary to reasonably allocate the machining allowance of each process based on the material removal amount and precision requirements of the parts; When dividing the processing area according to the features of the parts, the feasibility and efficiency of the processing technology should be taken into consideration.

3. The method for optimizing the CNC machining path of a landing gear shell according to claim 2, characterized in that: Initial machining path generation and parameter setting, including: Import the 3D model of the landing gear housing into the software, perform model repair and simplification, and remove unnecessary details. For rough machining path generation, select the follow-part strategy and set the cutting layer, step length, and cutting direction parameters to achieve efficient material removal. The generation of finishing paths requires strategic selection based on the surface curvature; Tool selection requires comprehensive consideration of processing technology, material properties, and part structure; for rough machining, a large-diameter insert milling cutter is used; for fine machining, a small-diameter integral milling cutter is used to ensure accuracy; When initially setting the cutting parameters, refer to the cutting parameter table provided by the tool supplier and make adjustments based on the material properties.

4. The method for optimizing the CNC machining path for landing gear shell machining according to claim 1, characterized in that: Parameter adjustments driven by the path optimization algorithm include: Use Dijkstra algorithm to optimize the processing sequence of each processing area, calculate the shortest path between each area based on the part coordinate system, and reduce the tool travel distance; Adjust the step size by controlling the constant stub height. Set the stub height parameter in the CAM software, and the software will automatically adjust the step size according to the surface curvature. Create a processing time , surface roughness , tool wear Multi-objective optimization function: ; Where x represents the weight factor corresponding to the cutting parameters machining time, surface roughness, and tool wear; It is the preset standard processing time; The multi-objective optimization function is solved to find the optimal combination of cutting parameters while meeting the machining accuracy requirements.

5. The method for optimizing the CNC machining path for landing gear shell machining according to claim 4, characterized in that: The process of obtaining the processing time includes: According to the motion trajectory and cutting parameters of the tool during the machining process, the time required for the tool to cut each area is obtained through geometric calculation, and then the time of each area is accumulated to obtain the machining time.

6. The method for optimizing the CNC machining path for landing gear shell machining according to claim 5, characterized in that: The surface roughness acquisition process includes: Tool parameters include tool tip radius , main declination angle , secondary deflection angle , tool feed ; The cutting motion includes the synthetic trajectory of cutting speed and feed rate; When the tool is a sharp tool, the residual area is determined by the main deflection angle and the secondary deflection angle. The calculation formula for the residual area and the residual area height is: ; When the tool has a nose arc radius When , the residual area height can be approximated as: ; A height threshold is preset, and the height of the residual area above the height threshold is recorded as the roughness height; Obtain all roughness heights corresponding to the residual material after tool cutting, and count all the roughness heights to obtain the total roughness height; Based on the tool's travel path, the total travel length of the tool is obtained; the total roughness height is divided by the total travel length of the tool to obtain the unit length roughness; a unit length roughness threshold is preset, and the unit length roughness is divided by the unit length roughness threshold to obtain the surface roughness.

7. The method for optimizing the CNC machining path for landing gear shell machining according to claim 6, characterized in that: The process of obtaining the tool wear amount includes: Calculate the heat of plastic deformation: ; in It is the equivalent stress on the workpiece material in the cutting area; is the equivalent strain of the workpiece material in the cutting zone; is the equivalent strain rate; is the proportional coefficient of plastic work converted into heat energy; Calculate frictional heat: ; is the coefficient of friction; It is the normal contact force at the tool-chip and tool-workpiece contact interfaces; is the cutting speed; Correlating the plastic deformation heat with the friction heat, we get the thermal correlation: ; in is the stress integral in the contact area, is the normal stress in the contact area, is the infinitesimal area of ​​the contact zone; Based on the fact that tool hardness H is a function of temperature T, the hardness temperature function is obtained: ; Substituting the thermal correlation and hardness temperature function into the formula: ; Where K is the wear coefficient; is the initial normal force; is the thermal coefficient; is the room temperature hardness; is the thermal softening coefficient; The subsequent entry formula: ; Get the tool wear amount; where is the initial wear amount.

8. The method for optimizing the CNC machining path for landing gear shell machining according to claim 1, characterized in that: Virtual simulation verification and path correction, including: Using CNC machining simulation software, import optimized tool paths, machine tool models, fixture models, and part blank models to perform virtual machining of the entire process; The collision detection function of the simulation software can be used to check the interference and collision between the tool and the fixture and machine tool in real time. At the same time, the cutting analysis function of the software can be used to detect overcutting and undercutting during the cutting process, observe the distribution of cutting force and cutting heat, and predict the deformation of thin-walled areas through finite element coupling simulation.

9. The method for optimizing the CNC machining path for landing gear shell machining according to claim 1, characterized in that: Physical processing verification and process solidification: Conduct first-piece trial processing, collect processing data to evaluate optimization effects, organize the final optimization plan into standardized process documents, and establish an enterprise processing knowledge base.

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