Aluminum magnesium alloy precision molding forming process and forming equipment

Abstract

The invention relates to the technical field of forming processes and forming equipment, in particular to an aluminum-magnesium alloy precision plastic forming process and forming equipment, which comprises the following steps: S1, carrying out gradient temperature pretreatment on an aluminum-magnesium alloy blank with the initial heating temperature T meeting # imgabs0 #, S2, applying dynamic pressure P in a hydraulic forming stage with the calculation model being # imgabs1 #, S3, applying dynamic pressure P in a hydraulic forming stage with the initial heating temperature T meeting the initial heating temperature T meeting # imgabs0 #; s3, a springback compensation algorithm is adopted in the cold roll forming stage, and the compensation angle theta comp is determined by the following formula: # imgabs2; according to the aluminum-magnesium alloy precision plastic forming process and forming equipment provided by the invention, the problems of rebound control, surface quality and residual stress in aluminum-magnesium alloy precision plastic forming are solved through full-flow process optimization and innovation of high-precision forming equipment; and a high-reliability solution is provided for aerospace precision components, new energy automobile lightweight components and the like, and remarkable technical advancement and industrialization value are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of forming processes and forming equipment. Specifically, it particularly relates to a precision plastic forming process and forming equipment for aluminum-magnesium alloy. Background Art

[0002] In the prior art, due to its light weight, high specific strength, and excellent corrosion resistance, aluminum-magnesium alloy is widely used in fields such as aerospace, new energy vehicles, and consumer electronics. However, its precision plastic forming faces the following technical challenges: For example, the forming accuracy is insufficient. When cold forming aluminum-magnesium alloy, the springback effect is significant. Traditional processes rely on empirical compensation and it is difficult to achieve a tolerance control of ±0.1 mm level; residual stress accumulates. Residual stress caused by plastic deformation is likely to cause workpiece deformation and cracking. The temperature control of traditional annealing processes is rough and the stress elimination efficiency is low; there is a contradiction between die life and surface quality. For example, although high-hardness dies are wear-resistant, they are prone to adhesion with the alloy, resulting in deterioration of the surface roughness of the formed parts (Ra > 1.6 μm); the stability of the hydraulic system is poor. When there are dynamic pressure fluctuations (>5%), it exacerbates local overload of the material and causes defects such as microcracks in the material. In view of the above defects, the present invention provides a precision plastic forming process and forming equipment for aluminum-magnesium alloy. Through the optimization of the whole process and the innovation of high-precision forming equipment, it has overcome the problems of springback control, surface quality, and residual stress in the precision forming of aluminum-magnesium alloy, providing a highly reliable solution for aerospace precision components, lightweight components of new energy vehicles, etc., and having significant technical advancement and industrialization value. Summary of the Invention

[0003] In order to achieve the above object, the present invention adopts the following technical solutions: A precision plastic forming process for aluminum-magnesium alloy, comprising the following steps: S1. Perform gradient temperature pretreatment on the aluminum-magnesium alloy blank, and the initial heating temperature T satisfies: , where T m is the melting point of the material (°C), represents a coefficient, is the alloy element compensation coefficient, t pre is the holding time (min), t 0 is the reference time; S2. Apply a dynamic pressure P during the hydroforming stage, and its calculation model is: , where K is the material forming coefficient, σ s is the yield strength of the material (MPa), δ is the sheet thickness (mm), R is the die fillet radius (mm), t is the forming time (s), n is the hardening index, α is the strain rate sensitivity coefficient, is the equivalent plastic strain increment; represents the key correction term for the strain rate sensitivity and plastic deformation cumulative effect of the material in the dynamic pressure model; S3. During the cold bending forming stage, a springback compensation algorithm is adopted to compensate the angle θ comp which is determined by the following formula: , where is the target angle, β is the material compensation factor, E is the elastic modulus (GPa), and R d is the radius of the bending neutral layer (mm); S4. Implement a deformation-annealing composite treatment, and the annealing temperature T anneal satisfies: , where CAl and CMg are the mass percentages of aluminum and magnesium respectively.

[0004] Furthermore, the gradient temperature pretreatment includes three stages. In the first stage, the heating rate is increased to 200 - 250 °C at a rate of 8 - 12 °C / min. In the second stage, the heating rate is increased to 300 - 350 °C at a rate of 2 - 5 °C / min. During the third stage of heat preservation, mechanical vibration with an amplitude of 0.1 mm - 0.3 mm is implemented.

[0005] Furthermore, the real-time regulation of the dynamic pressure P applied in the hydroforming stage satisfies , and the material forming coefficient K is adjusted by feedback through online strain measurement. The adjustment amount , where is the difference between the dynamic pressure P and the preset target pressure value , is the preset target pressure value, represents the actual strain value measured online, represents the expected strain value calculated theoretically, is the change amount of the material forming coefficient K.

[0006] Furthermore, the process of the cold bending forming stage adopts a multi-axis linkage compensation strategy. When the bending radius R ≤ 5δ, the material compensation factor takes the upper limit value; when R ≥ 10δ, the corrected material compensation factor is corrected according to the following formula: , When 5δ ≤ R ≤ 10δ, the material compensation factor remains , and no correction is required, where δ is the material thickness.

[0007] Furthermore, it also includes a residual stress elimination process (S5), where the shot peening intensity is determined by the following formula: , where HV is the Vickers hardness of the material, which characterizes the ability of the material to resist plastic deformation, and σ resis the measured residual stress (MPa), obtained by non-destructive testing or the drilling method. is the yield strength of the material, representing the critical stress at which the material begins to undergo plastic deformation. Ac is the cross-sectional area correction factor (0.8 - 1.2), used to adjust the shot peening intensity according to the workpiece geometry. is the theoretical strength index of shot peening, comprehensively reflecting the elimination effect of process parameters on residual stress. is the empirical coefficient, optimized based on shot peening process experimental data or material properties, used to balance the formula dimension and physical meaning. represents the normalized reference value of Vickers hardness (unit: HV).

[0008] Furthermore, a nano-textured coating is provided on the surface of the mold, where the parameters of the coating satisfy the following conditions: Structure density D: The number of pits per unit area is 2500 - 5000 per square millimeter, used to optimize material fluidity and friction characteristics. Pit morphology ratio: The ratio of the depth h to the diameter d of a single pit satisfies h / d = 0.2 - 0.4, to balance the wear resistance and lubrication effect of the coating.

[0009] Furthermore, an axial pressure F is applied during the cold bending forming stage, and its value range is determined by the following formula: , where k range represents the empirical adjustment coefficient, set k range = 0.15 - 0.25, P hyd is the maximum pressure during the hydroforming process (unit: MPa); A cross is the cross-sectional area of the material to be processed (unit: mm 2 ); F is the axial pressure, used to control material flow and suppress warping deformation during the forming process.

[0010] A forming device for implementing any one of the above aluminum-magnesium alloy precision plastic forming processes includes: A hydraulic system, including a distributed servo cylinder group and a matching distributed servo proportional valve group, where the pressure control resolution of the distributed servo proportional valve group is not greater than 0.1 MPa; A six-degree-of-freedom cold bending actuator, composed of a base, multi-stage folding arms, and a terminal compensation module. The terminal compensation module is equipped with a three-dimensional laser locator and a gyroscope to achieve ±0.5 mm translation compensation and ±0.1° rotation compensation; An on-line monitoring system, integrated with a laser Doppler strain sensor and a dual-band infrared temperature measurement unit, and the measurement data is transmitted through an industrial Ethernet. Composite die quick-change device, including an electromagnetic locking unit, a pneumatic ejecting mechanism, a die mounting substrate and a die. Laser alignment reference points are provided at the center or four corners of the die mounting substrate for laser calibration during die positioning. The electromagnetic locking unit is embedded inside the die mounting substrate and locks by adsorbing the bottom of the die through electromagnetic force. The pneumatic ejecting mechanism is integrated below or on the side of the die mounting substrate and is connected to the contact surface of the die through a pneumatic piston. Among them, the distributed servo proportional valve group establishes real-time communication with the servo driver of the cold bending actuator through the PROFINET bus, and the data processor of the online monitoring system dynamically adjusts the working parameters of the composite die quick-change device through the PID adaptive algorithm.

[0011] Further, the distributed servo oil cylinder group is connected to the active joint shaft of the multi-stage folding arm through a spherical hinge joint to transmit the forming pressure. The optical path reflector of the three-dimensional laser locator is embedded in the side wall of the die cavity. The dual-band infrared temperature measurement unit is fixed to the adjustable cloud platform above the die through a magnetic adsorption bracket. The distance between the Halbach magnetic array of the die mounting substrate and the dual-band infrared temperature measurement unit is ≤5mm to detect the die offset in real time. The distributed servo proportional valve group is synchronized with the servo motor of the multi-stage folding arm through the EtherCAT bus. The multi-stage folding arm is equipped with a torque feedback device. When the deviation between the actual bending torque M and the theoretical value exceeds 15%, the angle correction program is automatically triggered, and the correction amount , where, represents the adjustment value of the amount to be corrected, represents the theoretical value or reference value of the original parameter, represents the actual measured value, that is, the bending torque value detected in real time by the torque sensor during the forming process; represents the theoretical model prediction value, that is, the expected bending torque value calculated through the material mechanics model, process parameter simulation or historical data; KM represents the correction coefficient (dimensionless), and the value range is 0.6≤KM≤0.9, which is used to adjust the correction amplitude to prevent overshoot.

[0012] Further, the hydraulic system is integrated with a pulsation suppression device, and its configuration is: (1) Dynamically attenuate the pressure pulsation in the hydraulic pipeline with a frequency range of 50Hz to 200Hz; (2) In the frequency range, the pressure fluctuation attenuation rate of the pulsation suppression device satisfies: , where, represents the pressure fluctuation attenuation amount (unit: dB) at the frequency f of the pressure pulsation, which is defined as the logarithmic ratio of the output pressure amplitude to the input pressure amplitude; denotes the amplitude of pressure pulsation at the input end of the hydraulic system (unit: MPa), measured by a pressure sensor upstream of the pulsation suppression device; denotes the amplitude of pressure pulsation at the output end of the hydraulic system (unit: MPa), measured by a pressure sensor downstream of the pulsation suppression device; f denotes the frequency of pressure pulsation (unit: Hz), and the value range is: 50 Hz to 200 Hz.

[0013] Compared with the existing technology, the advantages of the present invention are as follows: The present invention provides a precision plastic forming process and forming equipment for aluminum-magnesium alloy. Through the process optimization of the whole process and the innovation of high-precision forming equipment, the problems of springback control, surface quality and residual stress in the precision forming of aluminum-magnesium alloy are overcome, providing a highly reliable solution for aerospace precision components, lightweight components of new energy vehicles, etc., and having significant technological advancement and industrialization value. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is the process flow chart in the present invention; Figure 2 is the structural framework diagram of the forming equipment in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0016] Embodiment 1, a precision plastic forming process for aluminum-magnesium alloy, as shown in the accompanying drawings of the specification Figure 1 includes the following steps: S1. Perform gradient temperature pretreatment on the aluminum-magnesium alloy blank, and the initial heating temperature T satisfies: , wherein, T m is the melting point of the material (°C), represents a coefficient, is the alloy element compensation coefficient, t pre is the heat preservation time (min), t 0 is the reference time, fixed at 10 min; In this embodiment, taking the aluminum-magnesium alloy AZ31B sheet (aluminum mass percentage CAl = 3%, magnesium mass percentage CMg = (91.5% - 93.5%)) as an example, the following parameters are set: The melting point of the material T m = 650 °C, Alloy element compensation coefficient ΔT a = 10 °C, Insulation time t pre = 30 min, reference time t 0 = 10 min, Calculate the initial heating temperature: T = 650×(0.35~0.45) + 10×In(10 / 30) = 650×0.4 + 30 = 260 + 30 = 290 °C, The actual heating temperature range is 290 °C ± 10 °C, and keep warm for 30 minutes.

[0017] S2. Apply dynamic pressure P during the hydroforming stage, and its calculation model is: , In this embodiment, in the formula, K is the material forming coefficient, and the range value is 0.8 - 1.2, σ s is the material yield strength (MPa), δ is the sheet thickness (mm), R is the die fillet radius (mm), t is the forming time (s), n is the hardening index, and the range value is 0.15 - 0.25. α is the strain rate sensitivity coefficient, and the range value is 0.02 - 0.05. The larger α is, the more significant the exponential decay is, indicating that the process design pays more attention to suppressing the stress mutation under high-speed deformation. is the equivalent plastic strain increment, indicating the accumulated plastic deformation amount of the material during the forming process. Increases, the work hardening phenomenon of the material is significant, and the forming resistance increases. It is expressed as the key correction term for the strain rate sensitivity and plastic deformation cumulative effect of the material in the dynamic pressure model; where the negative sign "-" indicates that as the equivalent plastic strain increases, the dynamic pressure P needs to decay exponentially. The correction logic is: when the material undergoes plastic deformation ( increases), work hardening will increase the material strength. If the pressure is applied directly according to the linear model, it may cause excessive deformation or cracking of the material. By introducing , the dynamic pressure P gradually decreases as the deformation amount increases to match the hardening characteristics of the material and avoid local stress concentration. It reflects the coupling relationship between the dynamic pressure P and the material hardening behavior in the forming process. By reducing the dynamic pressure P, the enhanced resistance ability of the material due to plastic deformation is offset to ensure the forming stability. Combining with the value of α, optimize the control strategy of the dynamic pressure P under high-speed deformation to prevent material failure. In this embodiment, the meanings and functions of each symbol in the formula are shown in the following table: Symbol Physical meaning Unit Typical value range Effect on dynamic pressure P K Material forming coefficient, reflecting the comprehensive influence of material fluidity and die friction Dimensionless 0.8～1.2 The larger K is, the higher the required dynamic pressure P is, indicating poor material fluidity or large frictional resistance σs Material yield strength, representing the critical stress for the material to start plastic deformation MPa 150 - 300 (aluminum-magnesium alloy) The higher σs is, the greater the dynamic pressure P needs to be increased to overcome the material's resistance to deformation δ Sheet thickness, the initial thickness of the aluminum-magnesium alloy blank mm 1~5 As the sheet thickness δ increases, the dynamic pressure P decreases because the force requirement per unit area decreases R Die fillet radius, the radius of curvature of the die edge mm 3~15 The smaller R is, the higher the dynamic pressure P is because the small fillet causes local stress concentration t Forming time, the duration of the hydraulic action s 5~30 As the time t increases, the dynamic pressure P decreases because the material has more time to flow and relax n Strain hardening index, characterizing the strength of the material's work hardening behavior Dimensionless 0.15~0.25 The larger n is, the more significant the material hardening is, and a higher dynamic pressure P is required to maintain plastic deformation α Strain rate sensitivity coefficient, reflecting the dependence of material strength on the strain rate Dimensionless 0.02~0.05 The larger α is, the more obvious the attenuation of the dynamic pressure P with the increase of the strain rate, suppressing the stress mutation under high-speed deformation Δε Equivalent plastic strain increment, the accumulated plastic deformation of the material during the forming process Dimensionless 0.05~0.5 <![CDATA[Δε does not increase, and the exponential term e -αΔε attenuates the dynamic pressure P to match the material hardening characteristics]]> In this embodiment, 1. Perform parameter selection and setting: Material forming coefficient K = 1.0, Yield strength σ s = 200 MPa, sheet thickness δ = 2 mm, mold fillet radius R = 5 mm, forming time t = 10 s, strain hardening exponent n = 0.2, strain rate sensitivity coefficient α = 0.03, equivalent plastic strain increment Δη = 0.1; 2. Calculate the dynamic pressure P: ; In this embodiment, the actual forming pressure is controlled at 85 MPa - 90 MPa.

[0018] S3. During the cold bending forming stage, a springback compensation algorithm is adopted to compensate the angle θ comp which is determined by the following formula: , where, is the target angle, β is the material compensation factor (0.12 - 0.18), E is the elastic modulus (GPa), R d is the bending neutral layer radius (mm); In this embodiment, 1. Set the following parameters: = 90°, material compensation factor β = 0.15, elastic modulus E = 45 GPa, bending neutral layer radius R d = 3 mm, sheet thickness δ = 2 mm; 2. Calculate the compensation angle θ comp : ; The actual mold compensation angle θ comp is set to 90.1° to offset the springback.

[0019] S4. Implement the deformation - annealing composite treatment, and the annealing temperature T anneal satisfies: , CAl and CMg are the mass percentages of aluminum and magnesium respectively, and 0.6 is an empirical coefficient, indicating the relationship between the annealing temperature and the melting point T of the material mThe proportional relationship of (unit: °C). In the conventional experimental scientific basis, the annealing temperature is usually 0.5 - 0.7 times the melting point of the material. Here, 0.6 is taken to balance the requirements of grain refinement and recrystallization; -50 is the aluminum element compensation coefficient, and the negative sign indicates that an increase in aluminum content requires a decrease in the annealing temperature. Aluminum may promote low-temperature recrystallization in the alloy, and this coefficient needs to be calibrated through experiments; +30 is the magnesium element compensation coefficient, and the positive sign indicates that an increase in magnesium content requires an increase in the annealing temperature. In this embodiment, magnesium may inhibit grain boundary migration, and a higher temperature is required to complete recrystallization. The coefficient is determined by fitting the alloy phase diagram; ±15 represents the allowable temperature fluctuation range. Considering factors such as batch differences of the material and temperature control accuracy of the equipment, the annealing temperature can be adjusted within this range. In this embodiment, the parameter correlation table is as follows: Symbol Physical meaning Value source Typical value example <![CDATA[T m > Material melting point Material physical property table (such as 650°C for AZ31B) 650℃ CAl Mass percentage of aluminum Alloy composition design (such as CAl = 3%) 3% CMg Mass percentage of magnesium Alloy composition design (CMg = 91.5% - 93.5%) 91.5%~93.5% 0.6 Melting point proportionality coefficient Empirical value (based on the recrystallization temperature range) Fixed value -50 Aluminum content compensation coefficient Experimental calibration (inhibitory effect of aluminum on the annealing temperature) Fixed value +30 Magnesium content compensation coefficient Experimental calibration (promoting effect of magnesium on the annealing temperature) Fixed value ±15 Allowed temperature fluctuation range Process tolerance design Control range The application examples are as follows: 1. Set the following parameters: Melting point of the material T m = 650 °C; Mass percentage of aluminum CAl = 3%, Mass percentage of magnesium CMg = 91.5% - 93.5%; 2. Calculate the annealing temperature : ; Annealing temperature Control it at 255 °C - 285 °C, keep it warm for 30 minutes and then cool down.

[0020] Through the above steps, the AZ31B aluminum-magnesium alloy sheet can achieve high-precision shaping. The surface roughness Ra of the final product is ≤ 0.8 μm, the dimensional tolerance is controlled within ±0.05 mm, and there are no crack defects.

[0021] Example 2. On the basis of the above Example 1, the gradient temperature pre-treatment includes three stages. In the first stage, the heating rate is increased to 200 - 250 °C at a rate of 8 - 12 °C / min. In the second stage, the heating rate is increased to 300 - 350 °C at a rate of 2 - 5 °C / min. During the third stage of heat preservation, mechanical vibration with an amplitude of 0.1 mm - 0.3 mm is applied. In this example, mechanical vibration can effectively eliminate the residual stress inside the material. By applying cyclic stress to the workpiece at the resonance frequency, the residual stress inside the workpiece can be offset or adjusted, thereby stabilizing the dimensional deformation of the workpiece. This method does not change the mechanical properties of the workpiece, and there will be no oxidation on the surface of the workpiece. It can also improve the microstructure of the material, making it more uniform and refined and enhancing the heat transfer efficiency of the material. During the heat preservation process, vibration can promote the uniform distribution of heat, reduce the temperature gradient, and thus improve the heat preservation effect. On the basis of combining Example 2 with the above Example 1, taking the aluminum-magnesium alloy AZ31B sheet (aluminum mass percentage CAl = 3%, magnesium mass percentage CMg = 91.5% - 93.5%) as an example, Step S1: Gradient temperature pre-treatment (including three-stage control); The first stage: Heating rate: 10 °C / min (within the range of 8 - 12 °C / min in Example 2); Target temperature: 220 °C (within the range of 200 - 250 °C); Operation: Heat the blank from room temperature to 220 °C at a rate of 10 °C / min, which takes about 20 minutes; The second stage: Heating rate: 3 °C / min (within the range of 2 - 5 °C / min in Example 2); Target temperature: 320 °C (within the range of 300 - 350 °C); Operation: Heat from 220 °C to 320 °C at a rate of 3 °C / min, which takes about 33 minutes; The third stage: Heat preservation temperature: 320 °C; Heat preservation time: 30 minutes (according to the heat preservation time t pre = 30 min in Example 1); Mechanical vibration: Apply vibration with an amplitude of 0.2 mm (within the range of 0.1 - 0.3 mm in Example 2) and a frequency of 50 Hz throughout the heat preservation stage to refine the grain structure; The implementation effect in this example: Forming accuracy: The dimensional tolerance of the final product is ±0.04 mm; Surface quality: Surface roughness Ra = 0.7 μm (meeting Ra ≤ 0.8 μm); Microstructure: The grain size ≤ 15 μm, without crack or hole defects; Through the collaborative control of three-stage gradient temperature pretreatment (including mechanical vibration) and dynamic pressure-rebound compensation in the above-mentioned embodiment process, the plastic forming precision and tissue uniformity of the aluminum-magnesium alloy are significantly improved, verifying the feasibility of the above-mentioned technical solution.

[0022] In Example 3, on the basis of the above-mentioned Example 1, the real-time regulation of the dynamic pressure P applied in the hydraulic forming stage satisfies , and the material forming coefficient K is adjusted by feedback through online strain measurement, and the adjustment amount , where is the preset target pressure value, is the difference between the dynamic pressure P and the preset target pressure value , The meaning expressed by the formula is: The ratio of the difference between the dynamic pressure P and the preset target pressure value to the preset target pressure value needs to be controlled within 3%.

[0023] Ensure the stability of the forming process: represents the actual strain value measured online, represents the expected strain value calculated theoretically, is the change amount of the material forming coefficient K, and the meaning expressed in the formula is: According to the ratio of the actual strain value to the expected strain value, the material forming coefficient K is adjusted and controlled proportionally (0.15 is an empirical coefficient) to achieve the real-time feedback control of the dynamic pressure P.

[0024] In this embodiment, combining the technical solutions in Example 1 and this embodiment, the specific implementation process is described: Step S1: Gradient temperature pretreatment (the same as the previous example, including three-stage heating and mechanical vibration, specific parameters are omitted); Step S2: Real-time regulation of the dynamic pressure P in the hydraulic forming stage, 1. Initial parameter setting: The original material forming coefficient K = 1.0 (within the range of 0.8 - 1.2); Yield strength σ s = 200 MPa, sheet thickness δ = 2 mm; Mold fillet radius R = 5 mm, forming time t = 10 s; Hardening index n = 0.2, strain rate sensitivity coefficient α = 0.03, equivalent plastic strain increment Δε = 0.1; 2. Theoretical dynamic pressure calculation: , Set the initial forming dynamic pressure P = 87 Mpa; 3. Real-time regulation process: On-line strain measurement: Use a laser strain gauge to monitor the actual strain value ε of the sheet in real time real , with a sampling frequency of 100 Hz; Expected strain value Calculation: According to the process model, the expected strain value , Adjust the material forming coefficient K: , When the actual strain value , , where K new represents the new coefficient obtained by correcting the original material forming coefficient K = 1.0; Dynamic pressure correction: , where, P new represents the adjusted pressure value calculated based on the correction coefficient K new ; Pressure fluctuation verification: , If it exceeds the 3% range, trigger the safety mechanism, and the system automatically adjusts in segments to , with the volatility reduced to ≤2.9%, where P final represents the final stable pressure value to which the system automatically adjusts in segments when the volatility of P new exceeds the safety threshold (3%).

[0025] Step S3, springback compensation in the cold bending forming stage (same as the previous example, the compensation angle calculation and die setting are omitted).

[0026] Step S4, deformation-annealing composite treatment (same as the previous example, the annealing temperature control and heat preservation operation are omitted).

[0027] The effects in this embodiment: Pressure regulation stability: The dynamic pressure fluctuation is controlled throughout within ∣ΔP / P set ∣≤3%, meeting the requirements of the technical solution in this embodiment; Forming accuracy: The dimensional tolerance of the final product is ±0.03 mm, better than ±0.05 mm in Example 1; Strain consistency: The ratio of the difference between the dynamic pressure P and the preset target pressure value to the preset target pressure value ≤5%, and the grain uniformity is improved by 20%; In this embodiment, the material forming coefficient K is adjusted in real time through online strain feedback, and combined with dynamic pressure segmented correction, the pressure fluctuation is effectively suppressed, verifying the technical advantages of the collaborative control in Embodiment 1 above in combination with this embodiment.

[0028] Embodiment 4. The process in the cold bending forming stage adopts a multi-axis linkage compensation strategy. When the bending radius R ≤ 5δ, the compensation factor β takes the upper limit value; when R > 10δ, the corrected compensation factor is corrected according to the following formula: , where in this embodiment, 0.08 is the correction coefficient, determined based on experiments or experience, reflecting the influence weight of the ratio of radius to thickness on the compensation factor, and 10 is the reference critical value used to divide the correction interval (correction is started when R / δ > 10); in this embodiment, in combination with the technical solutions in Embodiment 1 and this embodiment above, the specific implementation process of the multi-axis linkage compensation strategy for the process in the cold bending forming stage is described as follows: Step S1: Gradient temperature pre-treatment (same as the previous example, including three-stage heating and mechanical vibration, specific parameters are omitted); Step S2: Dynamic pressure application in the hydroforming stage (same as the previous example, including three-stage heating and mechanical vibration, specific parameters are omitted); Step S3: Multi-axis linkage compensation strategy in the cold bending forming stage; Parameter setting: Target angle , The original value of the material compensation factor β = 0.18 - 0.24 (take the upper limit when R ≤ 5), Elastic modulus E = 45 GPa, sheet thickness δ = 2 mm.

[0029] Scenario 1: Bending radius R = 4 mm (R ≤ 5), Compensation factor selection: According to this embodiment, directly take β = 0.18, Bending neutral layer radius: R d = 3 mm, Compensation angle calculation: , Actual operation: The die angle is set to 90.2°, and the measured angle after forming is 89.8°, and the springback error ≤ 0.3.

[0030] Scenario 2: Bending radius R = 12 mm (R > 10) The corrected compensation factor : , The corrected compensation factor = 0.24 (rounded to two decimal places), Radius of the bending neutral layer: R d = 10 mm, Calculation of the compensation angle: , Actual operation: The die angle is set to 92.4°, and the measured angle after forming is 89.7°. The springback error is corrected to ≤0.5° through the multi-axis linkage dynamic compensation strategy.

[0031] Step S4, strain-annealing composite treatment (same as the previous example, the annealing temperature control and heat preservation operation are omitted).

[0032] Effects in this embodiment: Adaptability of the compensation strategy: When R ≤ 5 mm, directly take the upper limit value of β (0.18), and the compensation angle error ≤ 0.3. When R > 10 mm, correct the value of β (0.18 - 0.24) through the formula, and the compensation angle error ≤ 0.5°, meeting the requirements of complex curvature; Forming accuracy: The dimensional tolerance of the final product is ±0.04 mm, and the surface roughness Ra = 0.7 μm; Process stability: The multi-axis linkage compensation strategy significantly reduces the springback rate and improves the bending consistency.

[0033] In this embodiment, through the multi-axis linkage compensation strategy described above, the compensation factor β is dynamically adjusted according to different bending radii, effectively solving the problem of springback control in the cold bending forming of aluminum-magnesium alloy, and verifying the practicability and universality of the technical solution.

[0034] Example 5 also includes a residual stress elimination process (S5), where the shot peening intensity is determined by the following formula: , where HV is the Vickers hardness of the material, representing the ability of the material to resist plastic deformation, σ res is the measured residual stress (MPa), obtained by non-destructive testing or the drilling method, is the yield strength of the material, indicating the critical stress at which the material begins to undergo plastic deformation, Ac is the cross-sectional area correction factor (0.8 - 1.2), used to adjust the shot peening intensity according to the workpiece geometry; is the theoretical strength index of the shot peening treatment, comprehensively reflecting the elimination effect of process parameters on residual stress, is the empirical coefficient, optimized based on shot peening process experimental data or material properties, used to balance the formula dimension and physical meaning, represents the normalized reference value of the Vickers hardness (unit: HV).

[0035] A nano-textured coating is set on the surface of the die, where the parameters of the coating meet the following conditions: Structural density D: The number of pits per unit area is 2,500 - 5,000 per square millimeter, which is used to optimize the material fluidity and friction characteristics; Pit morphology ratio: The ratio of the depth h to the diameter d of a single pit satisfies h / d = 0.2 - 0.4 to balance the wear resistance and lubrication effect of the coating; An axial pressure F is applied during the cold bending forming stage, and its value range is determined by the following formula: , where k range = 0.15 - 0.25, P hyd is the maximum pressure during the hydroforming process (unit: MPa); A cross is the cross-sectional area of the component (unit: mm 2 ); F is the axial pressure, which is used to control the material flow and suppress the warping deformation during the forming process.

[0036] In this embodiment, combining the technical solutions of the above-mentioned embodiment 1 and this embodiment, the specific solution of this embodiment is described as follows: Step S1: Gradient temperature pretreatment (same as the previous example, including three-stage heating and mechanical vibration, specific parameters are omitted); Step S2: Application of dynamic pressure during the hydroforming stage: 1. Parameter setting: Maximum hydroforming pressure ; Cross-sectional area of the sheet ; 2. Dynamic pressure regulation (same as the previous example, adjust the material forming coefficient K in real time, omitted).

[0037] Step S3, Application of axial pressure during the cold bending forming stage: 1. Axial force calculation: , Actual operation: Apply an axial pressure F = 800 N (within the calculated range, used to suppress warping deformation); 2. Multi-axis linkage compensation strategy (same as the previous embodiment 4).

[0038] Step S4: Deformation-annealing composite treatment: 1. Parameter setting: Empirical coefficient K 1 = 0.5, Material Vickers hardness HV = 80, Normalized reference value of Vickers hardness HV base = 200, Measured residual stress σ res = 50 MPa, Yield strength σ s = 200 MPa, Cross-sectional area correction factor Ac = 1.0; 2. Calculation of theoretical strength index for shot peening: , Actual operation: Steel shot with a diameter of 0.3 mm is used, the shot peening time is 3 minutes, and the coverage rate is 200%, indicating that the area of the material surface impacted and covered by the shot is on average covered twice, and the residual stress is reduced to 1.8 MPa.

[0039] Step S5: Residual stress elimination: 1. Parameter setting: Tissue density D = 4000 pits / mm 2 (The number of pits per unit area is 2500 to 5000 per square millimeter), Pit depth h = 2 μm, diameter d = 8 μm, satisfying h / d = 0.25 (within the range of 0.2 - 0.4); 2. Coating preparation: A nano-textured coating is set on the mold surface using laser processing technology, The material of the set coating is TiN, with a thickness of 5 μm, and the friction coefficient is reduced to 0.12.

[0040] Deformation-annealing composite treatment (same as the previous embodiment, the annealing temperature control and heat preservation operation are omitted).

[0041] Technical effects and data table achieved by the implementation: Name Symbol Value / range Unit Remarks Theoretical strength index of shot peening <![CDATA[I shot > 0.02 N.S / mm2 Verification of the formula calculation result Structure density D 4000 Pits / mm2 In the range of 2000 - 5000 Pit morphology ratio h / d 0.25 - In the range of 0.2 - 0.4 Axial pressure F 800 N Calculation range within 652.5 - 1087.5N Measured residual stress after residual stress elimination <![CDATA[σ res > 18 MPa Shot peening residual stress reduced by 64% Surface roughness Ra 0.7 μm Better than the target value of 0.8μm Dimensional tolerance - ±0.03-±0.04 mm Meet the requirement of ±0.05 In this embodiment, the residual stress after shot peening is reduced to 18 MPa (original 50 MPa), verifying the effectiveness of the formula; Mold coating performance: The nano-textured coating reduces the friction coefficient to 0.12, and the surface roughness of the formed part is optimized to 0.6 μm; Axial pressure coordination: After applying an 800 N axial pressure, the cold bending springback rate is reduced by 18%, and the dimensional accuracy is significantly improved.

[0042] Example 6, a forming device for a precision plastic forming process of an aluminum-magnesium alloy, as shown in the attached drawings of the specification Figure 2 shown, including: A hydraulic system, including a distributed servo cylinder group and a distributed servo proportional valve group matching it, where the pressure control resolution of the servo proportional valve group is not greater than 0.1 MPa; Six-degree-of-freedom cold bending actuator, which consists of a base, multi-stage folding arms and an end compensation module. The end compensation module is configured with a three-dimensional laser locator and a gyroscope to achieve ±0.5mm translational compensation and ±0.1° rotational compensation; an on-line monitoring system, which is integrated with a laser Doppler strain sensor (accuracy ±0.01%) and a dual-band infrared temperature measurement unit (temperature measurement range 300 - 800°C), and the measurement data is transmitted through an industrial Ethernet. Composite die quick-change device, which includes an electromagnetic locking unit (locking force ≥5kN), a pneumatic ejection mechanism (response time ≤50ms), a die mounting substrate and a die. Laser alignment reference points are provided at the center or four corners of the die mounting substrate, and the repeat positioning accuracy of the laser alignment reference points is better than 0.005mm, which is used for laser calibration during die positioning; the electromagnetic locking unit is embedded inside the die mounting substrate and locks by adsorbing the bottom of the die through electromagnetic force; the pneumatic ejection mechanism is integrated below or on the side of the die mounting substrate and is connected to the contact surface of the die through a pneumatic piston. Among them, the distributed servo proportional valve group establishes real-time communication with the servo driver of the cold bending actuator through a PROFINET bus, and the data processor of the on-line monitoring system dynamically adjusts the working parameters of the die quick-change device through a PID adaptive algorithm; in this embodiment, the distributed servo oil cylinder group has 4 channels, and the response time of the distributed servo proportional valve group is ≤5ms.

[0043] Embodiment 7, the distributed servo oil cylinder group is connected to the active joint shaft of the multi-stage folding arm through a ball hinge joint to transmit the forming pressure; the optical path reflector of the three-dimensional laser locator is embedded in the side wall of the die cavity; the dual-band infrared temperature measurement unit is fixed on an adjustable cloud platform above the die through a magnetic adsorption bracket; the distance between the Halbach magnetic array of the die mounting substrate and the dual-band infrared temperature measurement unit is ≤5mm to detect the die offset in real time; the distributed servo proportional valve group is synchronized with the servo motor of the multi-stage folding arm through an EtherCAT bus; the multi-stage folding arm is equipped with a torque feedback device. When the deviation between the actual bending torque M and the theoretical value exceeds 15%, the angle correction program is automatically triggered, and the correction amount , where represents the adjustment value of the amount to be corrected, represents the theoretical value or reference value of the original parameter, represents the actual measured value, that is, the bending torque value detected in real time during the forming process by a torque sensor; represents the theoretical model prediction value, that is, the expected bending torque value calculated through a material mechanics model, process parameter simulation or historical data, and KM represents the correction coefficient (dimensionless), and the value range is 0.6 ≤ KM ≤ 0.9, which is used to adjust the correction amplitude to prevent over-adjustment.

[0044] In this embodiment, the ball joint transfers pressure to the active joint axis of the multi-stage folding arm, with a maximum torque of 200 N·m. The optical path mirror is embedded in the side wall of the mold cavity, where the reflection angle accuracy is ≤0.1°. The magnetic adsorption bracket is installed on the adjustable cloud platform above the mold, and the temperature measurement range is 0 - 500°C. Among them, the distance between the Halbach magnetic array and the dual-band infrared temperature measurement unit is ≤5 mm, and the accuracy of detecting the mold offset is ±0.002 mm; When the actual measured value and the predicted value of the theoretical model have a deviation > 15%, the angle correction program is triggered: , where KM = 0.75 is set; When the actual measured value and the predicted value of the theoretical model have a deviation of 20%, in this embodiment, takes a value of 180 N·m, takes a value of 150 N·m, when taking a value of 90°, the correction amount is: , This formula dynamically generates the parameter correction amount by quantifying the deviation ratio between the measured value and the theoretical value and combining the correction coefficient KM, and is one of the core algorithms for realizing adaptive control or process optimization.

[0045] Embodiment 8, on the basis of the above embodiment, the hydraulic system is integrated with a pulsation suppression device, which is configured as: (1) Dynamically attenuate the pressure pulsation in the hydraulic pipeline with a frequency range of 50 Hz to 200 Hz; (2) Within the said frequency range, the pressure fluctuation attenuation rate of the pulsation suppression device satisfies: , where, represents the pressure fluctuation attenuation amount (unit: dB) at the frequency f of the pressure pulsation, and is defined as the logarithmic ratio of the output pressure amplitude to the input pressure amplitude; represents the pressure pulsation amplitude at the input end of the hydraulic system (unit: MPa), measured by a pressure sensor upstream of the pulsation suppression device; represents the pressure pulsation amplitude at the output end of the hydraulic system (unit: MPa), measured by a pressure sensor downstream of the pulsation suppression device; f represents the frequency of the pressure pulsation (unit: Hz), and the value range is: 50 Hz to 200 Hz.

[0046] In this embodiment, the verification steps of the pulsation suppression device are: 1. Set the verification parameters of the pulsation suppression device: The frequency f of the pressure pulsation: 50 - 200 Hz; The pressure fluctuation attenuation amount : 20 dB, satisfying the formula: ; 2. Test data: The pressure pulsation amplitude at the input end of the hydraulic system = 100 MPa (200 HZ), The pressure pulsation amplitude at the output end of the hydraulic system = 1.78 MPa, Calculate the pressure fluctuation attenuation .

[0047] Comparison table of example data: Technical parameters Example 6 Example 7 Example 8 Positioning accuracy ≤0.005mm Die offset accuracy ±0.002 — Pressure control resolution ≤0.1MPa — — Deviation between the actual bending moment M and the theoretical value triggers the angle correction program value — 15% deviation — Pressure fluctuation attenuation — — ≥20dB Friction coefficient (die coating) — 0.12 (TiN coating) — In the above embodiments, high precision, low fluctuation and fast response of the precision shaping of aluminum-magnesium alloy are achieved, and the equipment performance fully covers the process requirements.

[0048] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.

Claims

1. A precision forming process for aluminum-magnesium alloy, characterized in that: The following steps are involved: S1. Perform gradient temperature pretreatment on the aluminum-magnesium alloy billet, and the initial heating temperature T satisfies: , where T m is the melting point of the material (°C), represents the coefficient, is the alloy element compensation coefficient, t pre is the holding time (min), t0 is the reference time; S2. Dynamic pressure P is applied during the hydroforming stage, and its calculation model is: , where K is the material forming coefficient, σ s is the yield strength of the material (MPa), δ is the plate thickness (mm), R is the radius of the mold corner (mm), t is the forming time (s), n is the hardening index, α is the strain rate sensitivity coefficient, is the equivalent plastic strain increment; It is expressed as the key correction term in the dynamic pressure model for the material strain rate sensitivity and the cumulative effect of plastic deformation; S3, the springback compensation algorithm is used in the cold bending forming stage, and the compensation angle θ comp Determined by the following formula: , in, is the target angle, β is the material compensation factor, E is the elastic modulus (GPa), R d is the radius of the bending neutral layer (mm); S4, implement deformation-annealing composite treatment, annealing temperature T anneal satisfy: , CAl and CMg are the mass percentages of aluminum and magnesium respectively.

2. The aluminum-magnesium alloy precision forming process according to claim 1, characterized in that: The gradient temperature pretreatment includes three stages. In the first stage, the temperature is increased to 200-250°C at a rate of 8-12°C / min, and in the second stage, the temperature is increased to 300-350°C at a rate of 2-5°C / min. During the third stage of heat preservation, mechanical vibration with an amplitude of 0.1mm-0.3mm is implemented.

3. The aluminum-magnesium alloy precision forming process according to claim 1, characterized in that: The real-time regulation of the dynamic pressure P applied during the hydroforming stage satisfies , adjust the material forming coefficient K through online strain measurement feedback, and the adjustment amount ,in, The dynamic pressure P and the preset target pressure value The difference, is the preset target pressure value, Expressed as the actual strain value measured online, Expressed as the expected strain value calculated theoretically, To adjust the change in material forming coefficient K.

4. The aluminum-magnesium alloy precision forming process according to claim 1, characterized in that: The cold bending process adopts a multi-axis linkage compensation strategy. When the bending radius R≤5δ, the material compensation factor Take the upper limit value; when R ≥ 10δ, the corrected material compensation factor Corrected by the following formula: ， When 5δ≤R≤10δ, the material compensation factor remains , no correction is required, where δ is the material thickness.

5. The aluminum-magnesium alloy precision forming process according to claim 1, characterized in that: A residual stress relief step (S5) is also included, in which the shot peening intensity is determined by the following formula: ， Among them, HV is the Vickers hardness of the material, which represents the ability of the material to resist plastic deformation, σ res To measure the residual stress (MPa), obtain it through non-destructive testing or drilling method. is the yield strength of the material, indicating the critical stress at which the material begins to undergo plastic deformation, and Ac is the cross-sectional area correction factor (0.8~1.2), which is used to adjust the shot peening intensity according to the geometry of the workpiece; It is the theoretical strength index of shot peening treatment, which comprehensively reflects the effect of process parameters on the elimination of residual stress. It is an empirical coefficient, which is obtained based on shot peening process experimental data or material property optimization and is used to balance the dimension and physical meaning of the formula. Indicates the normalized reference value of Vickers hardness (unit: HV).

6. The aluminum-magnesium alloy precision forming process according to claim 1, characterized in that: A nanoscale textured coating is provided on the surface of the mold, wherein the parameters of the coating satisfy the following conditions: Structural density D: The number of pits per unit area is 2500~5000 / square millimeter, which is used to optimize the material fluidity and friction characteristics; Pit morphology ratio: The ratio of the depth h to the diameter d of a single pit satisfies h / d=0.2~0.4 to balance the wear resistance and lubrication effect of the coating.

7. The aluminum-magnesium alloy precision forming process according to claim 1, characterized in that: The axial pressure F is applied in the cold bending forming stage, and its value range is determined by the following formula: ， Among them, k range Indicates the experience adjustment coefficient, set k range =0.15~0.25, P hyd is the maximum pressure during the hydroforming process (unit: MPa); A cross is the cross-sectional area of ​​the material being processed (unit: mm 2 ); F is the axial pressure, which is used to control material flow and suppress warping deformation during the molding process.

8. A forming device for realizing the aluminum-magnesium alloy precision plastic forming process according to any one of claims 1 to 7, characterized in that: include: The hydraulic system includes a distributed servo cylinder group and a matching distributed servo proportional valve group, wherein the pressure control resolution of the distributed servo proportional valve group is not greater than 0.1MPa; The six-degree-of-freedom cold bending actuator consists of a base, a multi-stage folding arm and an end compensation module. The end compensation module is equipped with a three-dimensional laser locator and a gyroscope to achieve ±0.5mm translation compensation and ±0.1° rotation compensation; Online monitoring system, integrating laser Doppler strain sensor and dual-band infrared temperature measurement unit, with measurement data transmitted via industrial Ethernet; A composite mold quick-change device comprises an electromagnetic locking unit, a pneumatic ejection mechanism, a mold mounting base plate and a mold. A laser alignment reference point is provided at the center or four corners of the mold mounting base plate for laser calibration during mold positioning. The electromagnetic locking unit is embedded in the mold mounting base plate and locks the bottom of the mold by adsorbing the electromagnetic force. The pneumatic ejection mechanism is integrated below or on the side of the mold mounting base plate and connected to the contact surface of the mold through a pneumatic piston. The distributed servo proportional valve group establishes real-time communication with the servo driver of the cold bending actuator through the PROFINET bus, and the data processor of the online monitoring system dynamically adjusts the working parameters of the composite mold quick-change device through the PID adaptive algorithm.

9. The forming equipment for aluminum-magnesium alloy precision plastic forming process according to claim 8, characterized in that: The distributed servo cylinder group is connected to the active joint shaft of the multi-stage folding arm through a ball joint to transmit the molding pressure; the optical path reflector of the three-dimensional laser locator is embedded in the side wall of the mold cavity; the dual-band infrared temperature measurement unit is fixed to the adjustable pan / tilt above the mold through a magnetic bracket; the distance between the Halbach magnetic array of the mold mounting substrate and the dual-band infrared temperature measurement unit is ≤5mm, and the mold offset is detected in real time; the distributed servo proportional valve group is synchronized with the servo motor of the multi-stage folding arm through the EtherCAT bus; the multi-stage folding arm is equipped with a torque feedback device. When the actual bending torque M deviates from the theoretical value by more than 15%, the angle correction program is automatically triggered, and the correction amount ,in, Indicates the adjustment value of the amount to be corrected. Indicates the theoretical value or benchmark value of the original parameter, It represents the actual measured value, that is, the bending moment value detected in real time by the moment sensor during the forming process; It represents the predicted value of the theoretical model, that is, the expected bending moment value calculated through material mechanics model, process parameter simulation or historical data; KM represents the correction coefficient (dimensionless), with a value range of 0.6≤KM≤0.9, which is used to adjust the correction amplitude to prevent over-adjustment.

10. The forming equipment for aluminum-magnesium alloy precision plastic forming process according to claim 8, characterized in that: The hydraulic system is integrated with a pulsation suppression device, which is configured as follows: (1) Dynamically attenuate pressure pulsations in the hydraulic line with a frequency range of 50 Hz to 200 Hz; (2) Within the frequency range, the pressure fluctuation attenuation rate of the pulsation suppression device satisfies: ， in, It is expressed as the pressure fluctuation attenuation at the frequency f of the pressure pulsation (unit: dB), defined as the logarithmic ratio of the output pressure amplitude to the input pressure amplitude; It is expressed as the pressure pulsation amplitude at the input end of the hydraulic system (unit: MPa), measured by the pressure sensor upstream of the pulsation suppression device; It represents the pressure pulsation amplitude at the output end of the hydraulic system (unit: MPa), which is measured by the pressure sensor downstream of the pulsation suppression device; f represents the frequency of pressure pulsation (unit: Hz), and the value range is: 50Hz to 200Hz.

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