Air conditioner outdoor unit shell sheet metal stamping forming method

Abstract

The application discloses a kind of air conditioner outer casing sheet metal stamping forming methods, comprising the following steps: obtaining air conditioner outer casing three-dimensional digital model and extracting flanging, fillet, side wall and the geometric characteristics of drawing area, in combination with finite element simulation and the strain data of trial stamping, the fracture risk and wrinkle risk of different geometric partitions are evaluated, and the partition defect prediction result is generated;According to the risk weight of each partition risk degree, it is introduced into multi-objective optimization process, and process parameters such as blank holder force, stamping speed are iteratively optimized.The method can reflect the distribution of defect risk in different areas of the shell, improve the regional directivity of process parameter optimization, reduce blind trial mold, reduce the risk of wrinkling, cracking and other defects, improve the forming quality, dimensional accuracy and product consistency of air conditioner outer casing.

Description

Technical Field

[0001] This invention belongs to the field of sheet metal stamping technology, specifically relating to a sheet metal stamping method for an air conditioner outdoor unit housing. Background Technology

[0002] Air conditioner outdoor unit casings are typically manufactured using sheet metal stamping processes. These processes involve complex flanging structures and deep drawing, making them prone to defects such as wrinkling and cracking during stamping. Traditional stamping process parameter settings often rely on manual experience and repeated trial molding, resulting in long lead times, high costs, and difficulties in ensuring product consistency and dimensional accuracy.

[0003] In recent years, finite element simulation technology has been increasingly applied to the feasibility analysis of stamping processes. By establishing a finite element model of stamping forming, initial process parameters such as blank holder force and stamping speed can be obtained, and forming limit diagrams can be generated to assess the risk of forming defects. Based on this, some methods combine measured data from trial stamping with the forming limit diagram, that is, mapping sheet metal strain data onto the forming limit diagram to calculate the overall fracture risk coefficient and wrinkling risk coefficient. Then, using these risk coefficients as optimization objectives, a multi-objective optimization algorithm is used to iteratively optimize the process parameters.

[0004] However, the aforementioned defect assessment method based on trial stamping test data and forming limit diagrams still has significant shortcomings in practical applications: the defect assessment only outputs overall quantitative indicators such as fracture risk coefficient and wrinkling risk coefficient, which cannot reflect the spatial distribution differences of defect risks in different geometric regions of the shell. When the multi-objective optimization algorithm receives these overall indicators, it can only know the overall severity of the defect risk, but cannot identify whether the risk is mainly concentrated in the flanging fillet area or the drawing sidewall area. This leads to a lack of spatial directionality in the iterative adjustment of process parameters, requiring a large amount of blind searching to gradually approach a feasible solution; moreover, the unified adjustment of global parameters such as blank holder force and stamping speed, while improving the forming quality of high-risk areas, can easily damage other areas that were originally qualified, seriously restricting the efficiency of process parameter optimization and the regional balance of the final forming quality.

[0005] Therefore, in order to address the above-mentioned technical problems, it is necessary to provide a method for stamping and forming sheet metal casings for air conditioner outdoor units. Summary of the Invention

[0006] The purpose of this invention is to provide a sheet metal stamping method for air conditioner outdoor unit housing, which can solve the technical problems mentioned in the background art.

[0007] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0008] A method for sheet metal stamping forming of an air conditioner outdoor unit housing includes the following steps: S1, acquiring a three-dimensional digital model of the air conditioner outdoor unit housing, performing feature recognition and extraction on the three-dimensional digital model to obtain geometric feature parameters; S2, constructing a stamping forming finite element simulation model based on the geometric feature parameters and performing numerical simulation to obtain initial process parameters and forming limit diagrams; S3, controlling a stamping equipment to perform trial stamping on the sheet metal based on the initial process parameters, and synchronously collecting stamping process data during the trial stamping process to form real-time stamping data; S4, dividing the forming area of ​​the air conditioner outdoor unit housing into multiple geometric partitions according to the geometric feature parameters; extracting sheet metal strain data corresponding to each geometric partition from the real-time stamping data, mapping them to the forming limit diagrams respectively, and calculating the strain of each geometric partition. The following steps are taken: S5. The cracking risk coefficient and wrinkling risk coefficient of each geometric partition are determined. The cracking risk coefficient and wrinkling risk coefficient of each geometric partition are combined with the corresponding partition location label to generate a partition defect prediction result. S6. Based on the cracking risk coefficient and wrinkling risk coefficient of each geometric partition in the partition defect prediction result, a risk weight is assigned to each geometric partition. A weighted multi-objective fitness function is constructed using the risk weights, and a multi-objective optimization algorithm is used to iteratively adjust the initial process parameters to generate optimized process parameters. S7. The optimized process parameters are applied to continuously stamp the batch of sheet metal, and real-time stamping feedback data is collected synchronously during the continuous stamping process. The real-time stamping feedback data is used to dynamically compensate the optimized process parameters to complete the stamping of the air conditioner outdoor unit casing.

[0009] In one or more embodiments of the present invention, in S1, feature recognition and extraction are performed on the three-dimensional digital model to obtain geometric feature parameters, specifically including: performing cross-sectional analysis on the three-dimensional digital model to identify the flange height, flange angle, minimum fillet radius, maximum drawing depth, and flange width of the air conditioner outdoor unit casing; and combining the flange height, flange angle, minimum fillet radius, maximum drawing depth, and flange width into geometric feature parameters.

[0010] In one or more embodiments of the present invention, in S2, a stamping forming finite element simulation model is constructed and numerical simulation is performed based on the geometric feature parameters to obtain initial process parameters and forming limit diagram. Specifically, this includes: establishing a parametric finite element model containing a punch, die, blank holder, and sheet metal based on the geometric feature parameters; setting the constitutive parameters and friction coefficient of the sheet metal material in the parametric finite element model; performing a drawing forming simulation to obtain the blank holder force, stamping speed, and die clearance under defect-free conditions; and determining the blank holder force, stamping speed, and die clearance as initial process parameters; simultaneously, extracting the principal strain and secondary strain distribution from the results of the drawing forming simulation and drawing the forming limit diagram.

[0011] In one or more embodiments of the present invention, in S3, the stamping equipment is controlled to perform a trial stamping on the sheet metal based on the initial process parameters, and stamping process data is collected synchronously during the trial stamping process to form real-time stamping data. Specifically, this includes: writing the initial process parameters into the programmable logic controller of the stamping equipment to drive the stamping equipment to complete at least one trial stamping stroke; during the trial stamping stroke, stamping force signals, displacement signals, temperature signals, and sheet metal strain signals are collected synchronously through a piezoelectric force sensor, a grating ruler displacement sensor, an infrared temperature sensor mounted on the mold, and a strain gauge attached to the surface of the sheet metal; and the stamping force signals, displacement signals, temperature signals, and sheet metal strain signals are time-aligned and filtered to form multi-channel real-time stamping data.

[0012] In one or more embodiments of the present invention, in S4, based on the geometric feature parameters, the forming area of ​​the air conditioner outdoor unit housing is divided into multiple geometric partitions; the sheet metal strain data corresponding to each geometric partition is extracted from the real-time stamping data and mapped to the forming limit diagram respectively, and the cracking risk coefficient and wrinkling risk coefficient of each geometric partition are calculated; the cracking risk coefficient and wrinkling risk coefficient of each geometric partition are combined with the corresponding partition location label to generate partition defect prediction results, specifically including: based on the maximum drawing depth and flanging angle in the geometric feature parameters, the forming area of ​​the air conditioner outdoor unit housing is pre-divided into three geometric partitions: flange area, side wall area, and rounded corner area; the flange area, side wall area, and rounded corner area are extracted from the real-time stamping data respectively. The corresponding sheet metal strain value at the end of the stamping stroke is obtained, and the maximum stamping force and sheet metal temperature change curves are extracted. The sheet metal strain values ​​at the end of the stamping stroke corresponding to the flange area, side wall area, and fillet area are mapped to the forming limit diagram respectively. The minimum distance between the sheet metal strain value of each geometric partition and the forming limit curve is calculated to obtain the fracture risk coefficient of each geometric partition. Using the maximum stamping force and sheet metal temperature change curves, combined with the local geometric features corresponding to each geometric partition in the geometric feature parameters, the wrinkling risk coefficient of each geometric partition is calculated respectively. The fracture risk coefficient and wrinkling risk coefficient of each flange area, side wall area, and fillet area are combined with the partition location label of each geometric partition to generate the partition defect prediction result.

[0013] In one or more embodiments of the present invention, in S5, risk weights are assigned to each geometric partition based on the fracture risk coefficient and wrinkling risk coefficient of each geometric partition in the partition defect prediction result; a weighted multi-objective fitness function is constructed using the risk weights, and the initial process parameters are iteratively adjusted using a multi-objective optimization algorithm to generate optimized process parameters. Specifically, this includes: using the initial process parameters as the initial solution; assigning risk weights to each geometric partition based on the magnitude of the fracture risk coefficient and wrinkling risk coefficient of the flange area, sidewall area, and fillet area, wherein geometric partitions with larger fracture risk coefficients or wrinkling risk coefficients are assigned higher risk weights; constructing a weighted multi-objective fitness function, wherein the weighted multi-objective fitness function... The first objective of the fitness function is the weighted total fracture risk obtained by summing the fracture risk coefficients of the flange area, sidewall area, and rounded corner area according to their respective risk weights. The second objective is the weighted total wrinkling risk obtained by summing the wrinkling risk coefficients of the flange area, sidewall area, and rounded corner area according to their respective risk weights. A non-dominated sorting genetic algorithm is used to perform multi-objective optimization on the blank holder force and stamping speed, with minimizing the weighted total fracture risk and weighted total wrinkling risk as the optimization direction, generating a Pareto front solution set. From the Pareto front solution set, a compromise solution is selected that makes both the weighted total fracture risk and weighted total wrinkling risk lower than their respective set thresholds, and the blank holder force and stamping speed corresponding to the compromise solution are used as the optimized process parameters.

[0014] In one or more embodiments of the present invention, in S5, the iterative adjustment of the initial process parameters using a multi-objective optimization algorithm is alternatively as follows: using the initial process parameters as the initial solution; determining the risk level of each geometric partition based on the magnitude of the fracture risk coefficient and wrinkling risk coefficient of the flange area, sidewall area, and fillet area; sequentially performing single-objective optimization on each geometric partition in descending order of risk level, wherein each single-objective optimization uses the weighted sum of the fracture risk coefficient and wrinkling risk coefficient of the current geometric partition as the objective function, and employs a particle swarm optimization algorithm to optimize the blank holder force and stamping speed, and after each single-objective optimization is completed, the obtained process parameters are used as the constraint boundary for the next geometric partition optimization; when all geometric partitions have completed single-objective optimization, the final blank holder force and stamping speed are used as the optimized process parameters.

[0015] In one or more embodiments of the present invention, in S4, the step of dividing the forming area of ​​the air conditioner outdoor unit housing into multiple geometric zones based on geometric feature parameters is alternatively performed as follows: based on the distribution of the minimum fillet radius in the geometric feature parameters, the forming area of ​​the air conditioner outdoor unit housing is adaptively meshed, the area with a fillet radius less than a preset threshold is divided into a high-risk fillet area, the area with a fillet radius greater than or equal to the preset threshold is divided into a low-risk fillet area, the flange plane area is divided into a flange area, and the side wall elevation area is divided into a side wall area; the high-risk fillet area, low-risk fillet area, flange area, and side wall area together constitute multiple geometric zones.

[0016] In one or more embodiments of the present invention, in step S6, the optimized process parameters are applied to continuously stamp and form a batch of sheet metal, and real-time stamping feedback data is collected synchronously during the continuous stamping process. The optimized process parameters are dynamically compensated using the real-time stamping feedback data. Specifically, this includes: loading the optimized process parameters into the stamping equipment and sequentially stamping the batch of sheet metal; continuously collecting the real-time peak value of the stamping force and the real-time final value of the sheet metal strain during each stamping stroke to form the real-time stamping feedback data; comparing the real-time peak value of the stamping force in the real-time stamping feedback data with the maximum stamping force across the entire range in the real-time stamping data formed in step S3 to obtain the pressure deviation; and adjusting the blank holder force in the optimized process parameters in real time using a PID controller based on the pressure deviation, so that the forming state of subsequent stamping approaches a defect-free state, until the stamping of all air conditioner outdoor unit housings is completed.

[0017] In one or more embodiments of the present invention, in step S6, the dynamic compensation of the optimized process parameters using the real-time stamping feedback data further includes: after each stamping stroke, extracting the real-time final value of the sheet metal strain corresponding to each geometric partition from the real-time stamping feedback data; comparing the real-time final value of the sheet metal strain corresponding to each geometric partition with the sheet metal strain value at the end of the stamping stroke of the corresponding geometric partition in step S4 to obtain the strain deviation of each geometric partition; when the strain deviation of any geometric partition exceeds a preset strain deviation threshold, using the PID controller to independently adjust the local blank holder force corresponding to that geometric partition in the next stamping stroke according to the strain deviation of that geometric partition, until the strain deviation of each geometric partition falls back to within the preset strain deviation threshold.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The air conditioner outdoor unit casing is divided into zones according to geometric features such as flanges, rounded corners, side walls, and drawing areas. The sheet metal strain data collected during the trial stamping process is then mapped to each geometric zone. With this zoned processing method, defect risks are no longer described by a single overall index, but can reflect the distribution of cracking and wrinkling risks in different areas of the casing, thereby clarifying the specific locations where defect risks are concentrated and their defect types.

[0020] Based on this, the present invention assesses the cracking risk and wrinkling risk of each geometric partition separately, and sets corresponding risk weights according to the risk level of different regions, so that the multi-objective optimization process can simultaneously focus on the overall forming quality and the forming state of local regions. Compared with the method of adjusting process parameters only based on the overall risk coefficient, the present invention can provide more specific regional directions for parameter iteration, reduce blind search caused by lack of risk location information, and improve the efficiency of process parameter optimization.

[0021] Furthermore, by incorporating the risk weights of each geometric zone into the stamping process parameter optimization process, it is possible to improve the forming quality of high-risk areas while taking into account the forming state of other areas. This avoids the adverse effects on originally qualified areas when adjusting process parameters such as blank holder force and stamping speed solely based on the overall evaluation results. As a result, it is beneficial to coordinate the forming quality between different areas, reduce the risk of defects such as local wrinkling, cracking, and excessive thinning, and improve the overall uniformity of the shell forming quality.

[0022] Furthermore, this invention combines three-dimensional geometric features, finite element simulation results, and experimental stamping data to perform zonal evaluation and risk-weighted optimization of the stamping process, providing clear geometric and data-based basis for determining process parameters and reducing reliance on manual experience and repeated mold trials. This can shorten the process debugging cycle, reduce the number of mold trials and material consumption, and improve the process development efficiency of complex flanging structures and large drawing depth air conditioner outdoor unit housings.

[0023] Through the above methods, this invention establishes a correlation between shell geometric feature analysis, forming defect zoning assessment and process parameter optimization, enabling the defect risk assessment results to effectively influence subsequent process adjustments. Compared with existing methods that only reflect the overall risk level, this invention can improve the controllability of the stamping process, reduce quality fluctuations between product batches, and help improve the dimensional accuracy, product consistency and forming qualification rate of air conditioner outdoor unit shells. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart illustrating the overall process of sheet metal stamping forming method for an air conditioner outdoor unit housing according to an embodiment of the present invention.

[0026] Figure 2 This is a flowchart illustrating the acquisition of geometric feature parameters and initial process parameters in one embodiment of the present invention;

[0027] Figure 3 This is a flowchart illustrating the generation of partition defect prediction results in one embodiment of the present invention;

[0028] Figure 4 This is a flowchart of the optimized process parameter generation and dynamic compensation process in one embodiment of the present invention;

[0029] Figure 5 This is a flowchart of a geometric partitioning alternative scheme in another embodiment of the present invention. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0031] A method for sheet metal stamping forming of an air conditioner outdoor unit housing according to an embodiment of the present invention includes the following steps:

[0032] like Figures 1-2 As shown, firstly, a three-dimensional digital model of the air conditioner outdoor unit casing is created using 3D modeling software. This 3D digital model can be a boundary representation model or a solid model containing complete geometric information of flanges, sidewalls, fillets, and flange surfaces. The file format can be STEP, IGES, Parasolid, or STL. After importing the 3D digital model into the feature recognition module, the feature recognition module establishes multiple cross-sectional analysis planes along the drawing direction, length direction, and width direction of the casing, and identifies the contour boundaries, curvature changes, and surface normals of each cross-section.

[0033] Through the above cross-sectional analysis, the flange height, flange angle, minimum fillet radius, maximum drawing depth, and flange face width are obtained respectively. Wherein, flange height is the normal distance from the outer edge plane of the flange to the reference plane containing the root of the adjacent sidewall; flange angle is the angle between the flange surface and the adjacent sidewall surface or a local tangent plane of the sidewall; minimum fillet radius is the minimum radius of curvature in each fillet transition region of the shell; maximum drawing depth is the maximum displacement of the sheet metal along the drawing direction during shell forming; flange face width is the effective width of the flange area along its extension direction. The five geometric parameters are structurally combined to obtain a set of geometric feature parameters:

[0034]

[0035] in, Indicates the flange height. Indicates the flange angle. Indicates the minimum fillet radius. Indicates the maximum drawing depth. Indicates the width of the flange face.

[0036] By converting complex surfaces, boundaries, and cross-sectional contours in a 3D model into structured geometric feature parameters, a unified input basis can be provided for subsequent finite element modeling and geometric partitioning. For mounting holes, process holes, local chamfers, or welding clearance grooves in the 3D model, the feature recognition module can mask local structures smaller than a preset area threshold before cross-sectional analysis to avoid misidentifying small local structures as major forming features.

[0037] After obtaining the geometric feature parameters, a finite element simulation model for stamping is established based on these parameters. The finite element simulation model includes a punch, a die, a blank holder, and sheet metal. The surface geometry of the punch and die is directly mapped from the three-dimensional digital model of the air conditioner outdoor unit housing. The blank holder is set as an annular blank holder structure matching the geometry of the flange area, and the sheet metal is placed between the die and the blank holder.

[0038] In the finite element model, the punch, die, and blank holder can be set as rigid bodies, while the sheet metal is set as an elasto-plastic deformable body. The sheet metal can be made of galvanized steel, cold-rolled steel, high-strength steel, or aluminum alloy. Taking HC340 / 590DP high-strength steel as an example, the Swift model can be used to describe the material hardening characteristics, and the Hill'48 anisotropic yield criterion can be used to describe the differences in plastic deformation along the rolling direction, transverse direction, and oblique direction. When the sheet metal grade changes, the hardening curve, yield criterion parameters, and forming limit data are replaced with actual material experimental data.

[0039] The sheet metal is discretized using shell elements suitable for large deformation analysis, such as the Belytschko-Tsay shell element. To improve the solution accuracy in the fillet transition region, the finite element mesh is locally refined in the fillet region, making the mesh size in the fillet region smaller than the mesh size in the planar region, preferably controlled within the range of half to one times the sheet metal thickness. A surface-to-surface contact relationship is established between the mold and the sheet metal, and the friction coefficient is set according to the actual lubrication conditions, preferably between 0.08 and 0.15.

[0040] After setting the material parameters, contact relationships, boundary conditions, and motion constraints of the finite element model, a drawing simulation is performed. The simulation process includes a blank holder closure stage and a stamping stage. In the blank holder closure stage, the blank holder ring applies a blank holder force to the flange area of ​​the sheet metal; in the stamping stage, the punch descends at a set stamping speed, and the sheet metal undergoes plastic flow under the combined action of the punch, die, and blank holder ring.

[0041] By changing the blank holder force, stamping speed, and die clearance, multiple sets of candidate process parameter combinations are obtained. These combinations are then screened based on the sheet thickness reduction rate, principal strain, secondary strain, and wrinkling trend in the flange area corresponding to each parameter set. When the maximum sheet thickness reduction rate does not exceed a preset reduction rate threshold, the maximum principal strain is lower than the allowable value of the corresponding forming limit curve, and no wrinkling ripples exceeding a preset height or wavelength threshold appear in the flange area, the corresponding blank holder force, stamping speed, and die clearance are determined as the initial process parameters.

[0042]

[0043] in, Indicates the initial blank holder force. Indicates the initial stamping speed. This indicates the initial die clearance. These initial process parameters provide a feasible starting point for subsequent trial stamping, thereby reducing the number of repeated trial stampings relying entirely on manual experience.

[0044] Simultaneously with the establishment of the finite element model and the selection of initial process parameters, the forming limit diagram is determined. This forming limit diagram can be obtained based on experimental data provided by the material supplier, or it can be fitted from Nakajima tests, Marciniak tests, or forming limit experimental data of other materials. By interpolating or fitting experimental data under different strain paths, a forming limit curve is obtained with secondary strain as the abscissa and principal strain as the ordinate.

[0045]

[0046] in, Indicates the principal strain. Indicates secondary strain. This represents the ultimate principal strain allowed for the sheet metal under the corresponding secondary strain conditions. Finite element simulation is used to obtain the principal and secondary strain distributions in various regions of the shell under specific process parameters, while the forming limit curve serves as the material instability boundary, used for subsequent assessment of the fracture risk based on the measured strain during trial stamping.

[0047] After obtaining the initial process parameters, they are written into the programmable logic controller (PLC) of the stamping equipment. The stamping equipment includes a frame, slide block, punch, die, blank holder, hydraulic or servo blank holder device, PLC, host computer, and sensor components. The PLC sends the blank holder force setpoint and stamping speed setpoint to the hydraulic proportional valve and servo drive unit respectively via analog output module or fieldbus, driving the stamping equipment to complete at least one trial stamping stroke.

[0048] Before the trial stamping begins, the sheet metal is placed in the die positioning area. When the sheet metal positioning sensor outputs a positioning signal, the safety light curtain outputs an allow signal, and the programmable logic controller confirms that the slider stroke zero point, die clearance, and blank holder force setting are all within the allowable range, the trial stamping process is triggered.

[0049] During the trial stamping process, multi-source sensors installed on the stamping equipment and mold synchronously collect stamping process data. Force sensors installed at the slider connection, die bearing seat, or main drive mechanism are used to collect the main stamping force signal; force sensors installed between the blank holder ring and the hydraulic cylinder or servo blank holder mechanism are used to collect the blank holder force signal; grating ruler displacement sensors installed on the side of the slider or the slider guide are used to collect the slider displacement signal; infrared temperature sensors installed on the side of the die and aligned with the sheet metal flange area, side wall area, or rounded corner area are used to collect the sheet metal temperature signal; strain gauges attached to preset monitoring points in the sheet metal flange area, side wall area, and rounded corner area are used to collect the sheet metal strain signal.

[0050] To ensure a unified time reference for data collected by different sensors, various signals are synchronously sampled via a synchronous acquisition card. The sampling frequency is preferably no less than 1kHz. A unified time zero point is established at the moment the slider begins its descent or the moment the main punch pressure first exceeds a preset contact threshold. The collected pressure, displacement, temperature, and strain signals are then filtered. This filtering can employ Kalman filtering, low-pass filtering, moving average filtering, or a combination thereof, to reduce the impact of equipment vibration, power frequency interference, and sensor random noise on subsequent risk assessment.

[0051] The processed real-time stamping data is represented as follows:

[0052]

[0053] in, The load signal represents the load during the stamping process, and the load signal includes the main punch force signal and / or the blank holder force signal; Indicates the slider displacement signal; This indicates the sheet metal temperature signal; and These represent the principal strain and the secondary strain, respectively. Thus, a correspondence is established between the theoretical process parameters obtained in the finite element simulation stage and the actual forming data obtained in the trial stamping stage.

[0054] like Figure 3 As shown, after obtaining real-time stamping data, the forming area of ​​the shell is geometrically partitioned according to the geometric feature parameters obtained in the aforementioned steps. For a typical air conditioner outdoor unit shell, the forming area can be divided into three geometric partitions: a flange area, a sidewall area, and a rounded corner area. The flange area is the flange plane area extending outward from the intersection of the sidewall and the flange plane; the sidewall area is the vertical surface area where the drawing depth reaches a preset proportion of the maximum drawing depth and the curvature change is relatively gentle, the preset proportion can be 60% to 90%, and is preferably 80% in this embodiment; the rounded corner area is the rounded transition area connecting the flange area and the sidewall area, the sidewall area and the bottom surface area, or the flange area and the adjacent wall surface.

[0055] Each geometric zone is assigned a zone location label, and a mapping relationship is established between the zone location label and the 3D model coordinates, finite element mesh element number, and strain gauge measurement point number. For example, the flange area can be labeled ZONE-1, the sidewall area ZONE-2, and the fillet area ZONE-3. Through this mapping relationship, the strain measurement point data in the real-time stamping data can be accurately assigned to the corresponding geometric zone.

[0056] Subsequently, the principal and secondary strains of each geometric zone at the end of the stamping stroke are extracted from the real-time stamping data. The end of the stamping stroke can be triggered by the slider displacement reaching the preset lower stop position, or by the main stamping force reaching its peak and entering a stable phase. When multiple strain measurement points are set for the same geometric zone, the average value, weighted average value, or the value of the highest risk measurement point can be taken as the strain state of that zone.

[0057] The principal and secondary strains of each geometric region are located as strain coordinate points in the principal-secondary strain coordinate system, and the minimum distance between each strain coordinate point and the forming limit curve is calculated. Preferably, the principal and secondary strains are normalized before calculating the distance to reduce the numerical scale difference between different strain directions.

[0058] The rupture risk coefficient of the ii-th geometric zone is calculated according to the following formula:

[0059]

[0060] in, This represents the rupture risk coefficient of the i-th geometric partition. This represents the minimum distance between the strain coordinate point of this zone and the forming limit curve. This indicates the preset safety threshold distance. This indicates the number of geometric partitions. The safety threshold distance can be determined based on material forming limit data and product quality requirements, for example, 5% of the maximum allowable principal strain value.

[0061] When the strain coordinate point is closer to the forming limit curve, The smaller the value, the closer the fracture risk coefficient is to 1, indicating that the zone is closer to the fracture state. When the strain coordinate point is far from the forming limit curve and the distance exceeds the safety threshold, the fracture risk coefficient is set to 0. If the strain coordinate point is located on the dangerous side of the forming limit curve, the fracture risk coefficient of the zone is directly set to 1, or an over-limit correction is made based on the distance calculation result, thereby avoiding the misjudgment of reduced risk caused by the increased distance after the strain point crosses the forming limit curve.

[0062] While calculating the fracture risk, the wrinkling risk is also calculated based on the local geometric characteristics, stamping load, and sheet temperature variations of each zone. The wrinkling risk is mainly related to the material inflow state in the flange area, local compressive stress, edge restraint, sheet temperature variations, and local geometric stability. Therefore, the critical wrinkling load for each geometric zone is first determined based on local geometric characteristics such as flange width, flange angle, local drawing depth, and fillet radius. The critical wrinkling load can be calculated using buckling theory or obtained from a historical process database.

[0063] Then, the peak value of the main punch pressure, the change in blank holder force, and the temperature change in each zone are compared with the corresponding critical wrinkling load to obtain the initial value of the wrinkling risk for each zone. For the implementation method using the main punch pressure as an indicator of material flow resistance, the closer the peak value of the main punch pressure is to or exceeds the local critical wrinkling load, the higher the wrinkling risk. For the implementation method using the blank holder force as an indicator of material inflow constraint, increasing the blank holder force can usually suppress wrinkling in the flange area, but may increase the risk of cracking in the fillet area and sidewall area. Therefore, the direction of the load parameters' effect on wrinkling risk is determined based on the collected load type and the corresponding geometric zone.

[0064] After normalization, the initial value of wrinkling risk is used to obtain a wrinkling risk coefficient ηw,iηw,i with a value range of 0 to 1. Thus, the fracture risk coefficient mainly reflects the degree of proximity between the zone strain state and the forming limit, while the wrinkling risk coefficient mainly reflects the coupling relationship between local geometric stability, material flow state, and edge constraint. The two correspond to different defect formation mechanisms.

[0065] Finally, the partition location labels, fracture risk coefficients, and wrinkling risk coefficients of each geometric partition are combined to generate partition defect prediction results. These results can further include partition risk level, the relative orientation of strain coordinate points to the forming limit curve, temperature change, peak main punch pressure, and sensor measurement point numbers. Compared to methods that only output overall fracture risk and overall wrinkling risk, partition defect prediction results can clearly reflect the spatial distribution of defect risks, providing location guidance for subsequent process parameter optimization.

[0066] like Figure 4 As shown, after obtaining the defect prediction results for each zone, the initial process parameters are used as the initial solution for the optimization iteration, and risk weights are assigned to each zone based on the fracture risk coefficient and wrinkling risk coefficient of each zone. The risk weight of the i-th geometric zone is:

[0067]

[0068] in, This represents the risk weight of the i-th geometric partition. This represents a very small positive number, preferably between 0.001 and 0.05; in this embodiment, it is 0.01. Since higher-risk partitions have larger risk coefficients, their risk weights are correspondingly increased. By adopting... This indicates the number of partitions. This risk weighting model is applicable to both three-partition and four-partition or more partition schemes.

[0069] Based on the risk weights of each partition, a weighted multi-objective fitness function is constructed. The first objective is the weighted sum of the rupture risk coefficients of each partition, and the second objective is the weighted sum of the wrinkling risk coefficients of each partition.

[0070]

[0071]

[0072] in, This represents the total weighted breakdown risk. This represents the total weighted wrinkle formation risk. The optimization algorithm aims to reduce this risk. and With the objective of optimizing the blank holder force and stamping speed, a multi-objective optimization is performed.

[0073] This embodiment employs a non-dominated sorting genetic algorithm for optimization. Each individual in the population represents a set of candidate process parameters, including at least blank holder force and stamping speed. The non-dominated level of each candidate individual is determined through rapid non-dominated sorting, and the diversity of the solution set is maintained through crowding distance. Subsequently, selection, crossover, and mutation operations are performed to generate the next generation of candidate parameters, and finite element simulation or surrogate model calculations are performed again to obtain the partition defect risk corresponding to the new candidate parameters.

[0074] The optimization process terminates when the number of iterations reaches the preset maximum number of generations, or when the change in the Pareto front solution set for multiple consecutive generations is less than a preset convergence threshold. Subsequently, a compromise solution is selected from the Pareto front solution set where both the weighted total fracture risk and the weighted total wrinkling risk are below the set thresholds. For example, a compromise solution can be selected where... The threshold is set to 0.3. The threshold is set to 0.4. When there are multiple compromise solutions that meet the threshold requirement, the solution closest to the risk origin is selected as the final solution, and the blank holder force, stamping speed, and die clearance corresponding to this solution are determined as the optimized process parameters.

[0075] After the optimized process parameters are determined, they are applied to the stamping equipment, and the batch of sheet metal is stamped sequentially. During the batch stamping process, real-time peak value of main punch pressure, real-time value of blank holder force, real-time final value of sheet metal strain, and sheet metal temperature change data are collected for each stamping stroke. The real-time peak value of main punch pressure in the current stamping stroke is compared with the reference peak value of main punch pressure in the trial stamping stage to obtain the pressure deviation.

[0076] Based on the pressure deviation, the global blank holder force is first coarsely adjusted. The control law of the PID controller is:

[0077]

[0078] in, Indicates the adjustment amount of the blank holder force. This indicates the deviation between the peak value of the main punch pressure during the current stamping stroke and the peak value of the reference main punch pressure during the trial stamping stage. , and These represent the proportional gain, integral gain, and derivative gain, respectively. The above continuous control law is executed discretized in a programmable logic controller according to a fixed sampling period.

[0079] In this embodiment, , and The values ​​can be 0.5, 0.05, and 0.01, respectively. The actual values ​​are adjusted based on the hydraulic response characteristics of the stamping equipment, the sheet thickness, the die structure, and the sampling period. To avoid drastic fluctuations in the blank holder force caused by sensor malfunctions or sudden disturbances, a limiting module is set at the output of the PID controller to limit the adjustment of the blank holder force to within 15% of the baseline value of the blank holder force in the optimized process parameters.

[0080] After coarse adjustment of the global blank holder force, fine adjustment of the local blank holder force is performed based on the strain deviation of each geometric zone. Specifically, the final strain value of each zone in the current stamping stroke is compared with the reference final strain value of the corresponding zone in the trial stamping stage. When the strain deviation of a certain zone exceeds the preset strain deviation threshold, only the local blank holder block corresponding to that zone is adjusted, without changing the blank holder state of other low-risk zones.

[0081] Localized blank holder force adjustment can be achieved through segmented blank holder rings, multi-cylinder hydraulic blank holder systems, or servo electric cylinder blank holder systems. Segmented blank holder rings divide the outer perimeter of the housing into multiple blank holder blocks, each driven by an independent hydraulic cylinder or servo electric cylinder, and establishing a correspondence with one or more geometric zones. For example, the flange area corresponds to the outer perimeter long-side blank holder block, the rounded corner area corresponds to the corner blank holder block, and the sidewall area corresponds to the adjacent transition blank holder block. By independently adjusting the output force of different blank holder blocks, when high strain occurs in the rounded corner area, the corresponding corner blank holder block can be adjusted first; when wrinkling tends to occur in the flange area, the constraint of the corresponding flange blank holder block can be increased, without simultaneously changing the blank holder state of the entire housing.

[0082] Therefore, this embodiment forms a dual-layer control structure combining global pressure compensation and localized strain compensation during the batch stamping stage. Global pressure compensation is used to suppress overall forming load changes caused by fluctuations in sheet metal properties, changes in lubrication conditions, and equipment drift; localized strain compensation is used to correct local forming anomalies in fillet areas, sidewall areas, or flange areas. Global compensation and local compensation are executed in the order of coarse adjustment followed by fine adjustment, thereby avoiding control conflicts caused by the simultaneous operation of the two control methods.

[0083] Preferably, an elastic transition gasket is provided between adjacent pressing blocks. The elastic transition gasket can be made of oil-resistant polyurethane material or spring steel sheet structure, used to buffer sudden pressure changes between adjacent pressing blocks and reduce indentations, local slippage and secondary wrinkling caused during local pressing force adjustment.

[0084] Preferably, a simplified rapid assessment of forming quality is performed between two adjacent stamping strokes. This rapid assessment incrementally calculates the fracture risk coefficient and wrinkling risk coefficient for each zone in the previous stamping stroke. When the risk coefficients of all zones are below 50% of their respective risk thresholds, the current optimized process parameters remain unchanged; when the risk coefficient of any zone exceeds 80% of its corresponding threshold, a pre-compensation amount proportional to the risk exceedance is superimposed on the local blank holder force corresponding to that zone, thereby correcting the local forming state in advance before the start of the next stamping stroke.

[0085] In another embodiment, the geometric partitioning method is replaced based on the above embodiment:

[0086] like Figure 5As shown, in this embodiment, instead of a fixed three-part division based solely on the flange area, sidewall area, and rounded corner area, adaptive partitioning is performed based on the spatial distribution of the shell's rounded corner radius. Specifically, the formed area of ​​the air conditioner outdoor unit shell is scanned in a grid, and the rounded corner radius at each grid node or local surface is calculated. When the rounded corner radius is less than a preset threshold, the corresponding area is classified as a high-risk rounded corner area; when the rounded corner radius is greater than or equal to the preset threshold, the corresponding area is classified as a low-risk rounded corner area; the flange plane area is classified as the flange area, and the sidewall elevation area is classified as the sidewall area.

[0087] The preset threshold can be determined based on the sheet thickness and the difficulty of shell forming, for example, three times the sheet thickness. This results in four geometric zones: high-risk rounded corner zone, low-risk rounded corner zone, flange zone, and sidewall zone. Since smaller rounded corner radii usually lead to more pronounced local stress concentration and material flow resistance, separating the small rounded corner area allows the optimization algorithm to further focus on areas with higher fracture risk.

[0088] When the shell has multiple rounded corner regions with different radii of curvature, two or more rounded corner radius classification thresholds can be set to further divide the rounded corner regions into high-risk, medium-risk, and low-risk rounded corner regions, which, together with the flange region and sidewall region, constitute five or more geometric partitions. In this case, the number of partitions in the aforementioned risk weight formula and weighted multi-objective fitness function... Adjustments will be made based on the actual number of partitions.

[0089] In another embodiment, the optimization algorithm is replaced as follows:

[0090] In the above embodiments, a non-dominated sorting genetic algorithm is used to simultaneously optimize the forming risk of multiple geometric partitions. In this embodiment, the comprehensive risk value is first calculated based on the cracking risk coefficient and wrinkling risk coefficient of each geometric partition, and the geometric partitions are arranged in descending order of comprehensive risk value.

[0091] Subsequently, using the initial process parameters as the initial solution, single-objective optimization is prioritized for the geometric partition with the highest overall risk value. The objective function is the weighted sum of the fracture risk coefficient and wrinkling risk coefficient of the current geometric partition, and a particle swarm optimization algorithm is used to search for the blank holder force and stamping speed. After completing the optimization of the high-risk partition, the obtained process parameters are used as the constraint boundary for the optimization of the next geometric partition, ensuring that subsequent partitions are optimized only within the neighborhood of the parameters determined in the previous stage.

[0092] By performing sequential optimization in descending order of risk level, the geometric areas most prone to cracking or wrinkling can be addressed first, while avoiding significant impact on areas that have already met forming requirements after subsequent parameter adjustments. This implementation method is suitable for stamping production scenarios with limited computing resources or high requirements for optimization response time.

[0093] In another embodiment, based on the above embodiments, the zoning risk assessment and process parameter optimization can be further extended:

[0094] When an infrared temperature sensor detects a significant change in sheet metal temperature during stamping, the temperature correction direction and coefficient can be determined based on material temperature test data, resulting in a corrected forming limit curve corresponding to the current temperature. Subsequently, the distance between the strain coordinate points of each zone and the forming limit curve is calculated using the corrected forming limit curve to obtain the temperature-corrected fracture risk coefficient. Since different materials exhibit different flow stress and forming limit variation patterns at different temperatures, the temperature correction coefficient should be determined based on specific material test data.

[0095] In the process of optimizing process parameters, in addition to blank holder force and stamping speed, die clearance, equivalent resistance coefficient of drawbeads, lubrication spraying amount, or output force of local blank holder blocks can also be included in the optimization variables. By expanding the range of optimization variables, the synergistic optimization of material feeding resistance, local blank holder state, and die structure parameters can be further achieved.

[0096] Furthermore, the location labels for each geometric partition can be encoded using a hierarchical naming method. For example, the first layer represents the shell region category, the second layer represents the forming feature category, and the third layer represents the partition number, thus forming hierarchical labels such as "FLANGE-01", "SIDEWALL-02", and "CORNER-03". This labeling method facilitates the storage, retrieval, and subsequent process parameter retrieval of partition defect prediction results.

[0097] Through the above implementation methods, this invention forms a complete technical chain from 3D model input to online control of batch stamping. The 3D digital model is first converted into geometric feature parameters, which are further used for finite element simulation and forming region partitioning; the finite element simulation outputs initial process parameters, and the material experimental data outputs forming limit diagrams; the initial process parameters drive trial stamping and generate real-time stamping data; the real-time stamping data, combined with geometric partitioning information and forming limit diagrams, forms partition defect prediction results carrying spatial location labels; the partition defect prediction results are further converted into partition risk weights and used to construct a weighted multi-objective fitness function; the optimization algorithm outputs optimized process parameters according to the fitness function; after the optimized process parameters enter the batch stamping stage, global and local dynamic compensation is performed based on the main stamping pressure and partition strain feedback.

[0098] Compared to existing methods that optimize parameters solely based on overall fracture risk and overall wrinkling risk, this invention can identify specific geometric regions where defect risks are concentrated and assign different optimization weights according to the risk level of different regions. Therefore, the optimization process can prioritize improving high-risk areas while reducing the adverse effects of global uniform adjustment on other acceptable areas. By combining global pressure compensation and localized strain compensation, it can also suppress the impact of material property fluctuations, lubrication changes, mold temperature rise, and equipment drift on forming quality during mass production, thereby improving the optimization efficiency of air conditioner outdoor unit casing stamping process parameters, regional forming uniformity, dimensional accuracy, and product consistency.

[0099] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0100] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for sheet metal stamping forming of an air conditioner outdoor unit housing, characterized in that, Includes the following steps: S1. Obtain a three-dimensional digital model of the air conditioner outdoor unit casing, and perform feature recognition and extraction on the three-dimensional digital model to obtain geometric feature parameters; S2. Based on the geometric feature parameters, construct a finite element simulation model for stamping and perform numerical simulation to obtain initial process parameters and forming limit diagram; S3. Based on the initial process parameters, control the stamping equipment to perform trial stamping on the sheet metal, and simultaneously collect stamping process data during the trial stamping process to form real-time stamping data; S4. Based on the geometric feature parameters, the forming area of ​​the air conditioner outdoor unit housing is divided into multiple geometric partitions; the sheet metal strain data corresponding to each geometric partition is extracted from the real-time stamping data, mapped to the forming limit diagram respectively, and the cracking risk coefficient and wrinkling risk coefficient of each geometric partition are calculated. The fracture risk coefficient and wrinkling risk coefficient of each geometric partition are combined with the corresponding partition location label to generate partition defect prediction results; S5. Based on the cracking risk coefficient and wrinkling risk coefficient of each geometric partition in the partition defect prediction results, assign a combined risk weight to each geometric partition. A weighted multi-objective fitness function is constructed using the risk weights, and a multi-objective optimization algorithm is used to iteratively adjust the initial process parameters to generate optimized process parameters. S6. Apply the optimized process parameters to continuously stamp and form batches of sheet metal, and simultaneously collect real-time stamping feedback data during the continuous stamping process. Use the real-time stamping feedback data to dynamically compensate the optimized process parameters and complete the stamping and forming of the air conditioner outdoor unit housing.

2. The sheet metal stamping forming method for the outdoor unit housing of an air conditioner according to claim 1, characterized in that, In S1, feature recognition and extraction are performed on the three-dimensional digital model to obtain geometric feature parameters, specifically including: Cross-sectional analysis was performed on the three-dimensional digital model to identify the flange height, flange angle, minimum fillet radius, maximum drawing depth, and flange width of the air conditioner outdoor unit casing; The flange height, flange angle, minimum fillet radius, maximum drawing depth, and flange width are combined into geometric feature parameters.

3. The sheet metal stamping forming method for the outdoor unit housing of an air conditioner according to claim 1, characterized in that, In S2, based on the geometric feature parameters, a finite element simulation model for stamping is constructed and numerical simulation is performed to obtain initial process parameters and forming limit diagrams, specifically including: Based on the geometric feature parameters, a parametric finite element model including the punch, die, blank holder and sheet metal is established. In the parametric finite element model, the constitutive parameters and friction coefficient of the sheet material are set, and the drawing forming simulation is performed to obtain the blank holder force, stamping speed and die clearance under defect-free conditions. The blank holder force, stamping speed and die clearance are then determined as the initial process parameters. Meanwhile, the principal strain and secondary strain distributions are extracted from the results of the drawing simulation, and the forming limit diagram is drawn.

4. The sheet metal stamping forming method for the outdoor unit housing of an air conditioner according to claim 1, characterized in that, In S3, the stamping equipment is controlled to perform trial stamping on the sheet metal based on the initial process parameters, and stamping process data is collected synchronously during the trial stamping process to form real-time stamping data, specifically including: The initial process parameters are written into the programmable logic controller of the stamping equipment, and the stamping equipment is driven to complete at least one trial stamping stroke. During the test stamping stroke, the stamping force signal, displacement signal, temperature signal and sheet strain signal are simultaneously collected by the piezoelectric force sensor, grating ruler displacement sensor, infrared temperature sensor installed on the mold and the strain gauge attached to the sheet surface; The stamping force signal, displacement signal, temperature signal, and sheet metal strain signal are time-aligned and filtered to form multi-channel real-time stamping data.

5. The sheet metal stamping forming method for the outdoor unit housing of an air conditioner according to claim 1, characterized in that, In S4, based on the geometric feature parameters, the forming area of ​​the air conditioner outdoor unit casing is divided into multiple geometric partitions; the sheet metal strain data corresponding to each geometric partition is extracted from the real-time stamping data, mapped to the forming limit diagram respectively, and the cracking risk coefficient and wrinkling risk coefficient of each geometric partition are calculated. The fracture risk coefficient and wrinkling risk coefficient of each geometric partition are combined with the corresponding partition location label to generate partition defect prediction results, specifically including: Based on the maximum drawing depth and flanging angle in the geometric feature parameters, the forming area of ​​the air conditioner outdoor unit casing is pre-divided into three geometric zones: flange area, side wall area, and rounded corner area. Extract the sheet metal strain values ​​at the end of the stamping stroke for the flange area, side wall area, and rounded corner area respectively from the real-time stamping data, and extract the maximum stamping force and sheet metal temperature change curves for the entire region. The sheet metal strain values ​​at the end of the stamping stroke corresponding to the flange area, side wall area and fillet area are mapped to the forming limit diagram respectively. The minimum distance between the sheet metal strain value of each geometric partition and the forming limit curve is calculated to obtain the fracture risk coefficient of each geometric partition. Using the maximum impact force and sheet temperature change curves across the entire area, and combining the local geometric features corresponding to each geometric partition in the geometric feature parameters, the wrinkling risk coefficient of each geometric partition is calculated respectively. The cracking risk coefficient and wrinkling risk coefficient of the flange area, sidewall area and rounded corner area are combined with the partition location label of each geometric partition to generate the partition defect prediction result.

6. The method for sheet metal stamping forming of an air conditioner outdoor unit housing according to claim 5, characterized in that, In S5, based on the cracking risk coefficient and wrinkling risk coefficient of each geometric partition in the partition defect prediction results, a combined risk weight is assigned to each geometric partition. A weighted multi-objective fitness function is constructed using the aforementioned risk weights. A multi-objective optimization algorithm is then used to iteratively adjust the initial process parameters to generate optimized process parameters, specifically including: The initial process parameters are used as the initial solution; Based on the magnitude of the cracking risk coefficient and wrinkling risk coefficient of the flange area, sidewall area and fillet area, risk weights are assigned to each of the geometric partitions, wherein the geometric partitions with larger cracking risk coefficients or wrinkling risk coefficients are assigned higher risk weights. A weighted multi-objective fitness function is constructed. The first objective of the weighted multi-objective fitness function is the weighted total fracture risk obtained by weighting the fracture risk coefficients of the flange area, sidewall area and fillet area according to their respective risk weights. The second objective is the weighted total wrinkling risk obtained by weighting the wrinkling risk coefficients of the flange area, sidewall area and fillet area according to their respective risk weights. A non-dominated sorting genetic algorithm is used to perform multi-objective optimization of the blank holder force and the stamping speed, with minimizing the total weighted fracture risk and the total weighted wrinkling risk as the optimization direction, and a Pareto front solution set is generated. From the Pareto front solution set, a compromise solution is selected that makes both the total weighted fracture risk and the total weighted wrinkling risk lower than their respective set thresholds. The blank holder force and stamping speed corresponding to this compromise solution are used as the optimized process parameters.

7. The method for sheet metal stamping forming of an air conditioner outdoor unit housing according to claim 5, characterized in that, In S5, the method of iteratively adjusting the initial process parameters using a multi-objective optimization algorithm is replaced by: The initial process parameters are used as the initial solution; The risk level of each geometric zone is determined based on the magnitude of the cracking risk coefficient and wrinkling risk coefficient of the flange area, sidewall area, and rounded corner area. According to the order of risk level from high to low, the geometric partitions are optimized one by one. Each single-objective optimization uses the weighted sum of the fracture risk coefficient and wrinkling risk coefficient of the current geometric partition as the objective function. The particle swarm optimization algorithm is used to optimize the blank holder force and stamping speed. After each single-objective optimization is completed, the obtained process parameters are used as the constraint boundary for the next geometric partition optimization. Once all geometric partitions have been optimized for a single objective, the final blank holder force and stamping speed will be used as the optimized process parameters.

8. The method for sheet metal stamping forming of an air conditioner outdoor unit housing according to claim 1, characterized in that, In S4, the method of dividing the forming area of ​​the air conditioner outdoor unit casing into multiple geometric partitions based on geometric feature parameters is alternatively described as follows: Based on the distribution of the minimum fillet radius in the geometric feature parameters, the forming area of ​​the air conditioner outdoor unit casing is adaptively meshed. Areas with fillet radii less than a preset threshold are classified as high-risk fillet areas, areas with fillet radii greater than or equal to the preset threshold are classified as low-risk fillet areas, the flange plane area is classified as the flange area, and the side wall elevation area is classified as the side wall area. The high-risk rounded corner area, low-risk rounded corner area, flange area, and sidewall area together constitute multiple geometric zones.

9. The sheet metal stamping forming method for an air conditioner outdoor unit housing according to claim 1, characterized in that, In step S6, the optimized process parameters are applied to continuously stamp and form batches of sheet metal. Real-time stamping feedback data is simultaneously collected during the continuous stamping process, and the optimized process parameters are dynamically compensated using this real-time stamping feedback data. Specifically, this includes: The optimized process parameters are loaded into the stamping equipment, and the batch of sheet metal is stamped sequentially. During each stamping stroke, the real-time peak value of the stamping force and the real-time final value of the sheet metal strain are continuously collected to form the real-time stamping feedback data. The real-time peak value of the stamping force in the real-time stamping feedback data is compared with the global maximum stamping force in the real-time stamping data formed in step S3 to obtain the pressure deviation. Based on the pressure deviation, the blank holder force in the optimized process parameters is adjusted in real time using a PID controller, so that the forming state of subsequent stamping approaches a defect-free state, until the stamping forming of all air conditioner outdoor unit housings is completed.

10. The method for sheet metal stamping forming of an air conditioner outdoor unit housing according to claim 9, characterized in that, In S6, the real-time stamping feedback data is used to dynamically compensate for the optimized process parameters, further including: After each stamping stroke, the real-time final value of the sheet metal strain corresponding to each geometric zone is extracted from the real-time stamping feedback data; The real-time final value of the sheet metal strain corresponding to each of the geometric partitions is compared with the sheet metal strain value at the end of the stamping stroke of the corresponding geometric partition in step S4 to obtain the strain deviation of each of the geometric partitions. When the strain deviation of any of the geometric partitions exceeds the preset strain deviation threshold, the PID controller is used to independently adjust the local blank holder force corresponding to that geometric partition in the next stamping stroke according to the strain deviation of that geometric partition, until the strain deviation of each geometric partition falls back to within the preset strain deviation threshold.

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