Method for stamping a volute spring for an aircraft

Abstract

The present application relates to the technical fields of aviation parts manufacturing and metal stamping forming, in particular to a stamping forming method for aviation volute spring, comprising the following steps: a data acquisition step: acquiring real-time modulus data of the plate to be processed and a target geometric trajectory equation; an energy mapping calculation step: performing energy mapping on the trajectory equation to determine a target strain energy density distribution graph representing energy dissipation gradient; a potential barrier parameter determination step: determining deformation energy potential barrier parameters of the current forming position in combination with the real-time modulus; a rheological compensation solution step: solving a rheological compensation control instruction set containing ultrasonic excitation and piezoelectric driving parameters based on the potential barrier parameters; a dynamic forming execution step: driving a dynamic rheological compensation die system to perform stamping operation; the present application realizes dimension upgrading from geometric shape copying to energy flow control, significantly improving the fatigue life and geometric consistency of the spring.

Description

Technical Field

[0001] This invention relates to the field of aerospace component manufacturing and metal stamping technology, specifically a stamping method for aerospace spiral springs. Background Technology

[0002] As a core energy storage component of aircraft instruments, aerospace spiral springs require extremely high complexity and precision in their manufacturing process. To ensure the linearity of the spring's output torque and fatigue life, a multi-pass stamping process is typically used to continuously plastically process high-strength alloy sheets. However, when controlling the forming of spiral springs with complex, gradually changing curvatures, it is necessary to calculate the deformation compensation amount along the forming path. The deformation compensation amount is a key indicator for evaluating whether the mold driving parameters match the material's rheological properties, and it directly relates to the geometric springback control and internal stress distribution after forming. To balance forming efficiency and geometric contour fit, existing technologies typically use a mapping method based on geometric rules to define the deformation compensation amount. The calculation of the deformation compensation amount is shown in the following formula: Although this calculation method establishes a linear relationship between geometry and compensation, the empirical rebound coefficient, determined through consulting manuals or trial and error, is still based on experience. However, it has strong static limitations;

[0003] This means that the control logic of the molding process is easily affected by the modulus fluctuation between material batches and non-uniform energy dissipation, resulting in the calculation results failing to reflect the actual physical rheological requirements. This lack of physical semantics not only reduces the consistency of the finished product, but may also cause irreversible microcracks inside the material due to overcompensation, which may have a negative impact on the service safety of aerospace components. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a method for stamping and forming a spiral spring for aviation applications. Specifically, the technical solution of the present invention includes:

[0005] The process involves acquiring real-time modulus data of the sheet material to be processed and the target geometric trajectory equation of the target spiral spring; performing energy mapping calculations on the target geometric trajectory equation to determine the target strain energy density distribution map, which characterizes the energy dissipation gradient of the sheet material from its initial state to its formed state; determining the deformation energy barrier parameter at the current forming position based on the target strain energy density distribution map and the real-time modulus data; calculating the rheological compensation control instruction set based on the deformation energy barrier parameter, wherein the rheological compensation control instruction set includes ultrasonic excitation parameters for adjusting the yield strength of the material and piezoelectric drive parameters for adjusting the local curvature of the mold; and driving the dynamic rheological compensation mold system to perform a stamping forming operation on the sheet material to be processed according to the rheological compensation control instruction set.

[0006] Preferably, obtaining the real-time modulus data of the sheet material to be processed includes: performing an online pre-stretching operation on the sheet material to be processed and collecting stress-strain response data; calculating the Young's modulus value of the sheet material to be processed based on the stress-strain response data, and determining the Young's modulus value as the real-time modulus data.

[0007] Preferably, the step of performing energy mapping calculation on the target geometric trajectory equation to determine the target strain energy density distribution map includes: constructing a path planning model based on the principle of minimum action, mapping the target geometric trajectory equation from Euclidean geometric space to a thermodynamic strain energy distribution model; and calculating the optimal solution for energy dissipation of the sheet material to be processed along the forming path in the thermodynamic strain energy distribution model to determine the target strain energy density distribution map.

[0008] Preferably, the step of calculating the rheological compensation control instruction set based on the deformation energy barrier parameter includes: determining, according to the deformation energy barrier parameter, the target acousto-plastic softening amplitude required to reduce the yield strength of the sheet material to be processed at the current forming position; and determining the ultrasonic excitation parameters according to the target acousto-plastic softening amplitude, wherein the ultrasonic excitation parameters include ultrasonic frequency and ultrasonic amplitude.

[0009] Preferably, the step of calculating the rheological compensation control instruction set based on the deformation energy barrier parameter further includes: predicting the nonlinear springback trend of the sheet material to be processed according to the deformation energy barrier parameter and the real-time modulus data; calculating the curvature correction amount for the dynamic rheological compensation mold system according to the nonlinear springback trend, and converting the curvature correction amount into the piezoelectric drive parameter.

[0010] Preferably, the method further includes: collecting real-time stamping resistance data during the stamping operation; generating a resistance state assessment result based on the real-time stamping resistance data and a preset resistance threshold range; and making real-time corrections to the rheological compensation control instruction set based on the resistance state assessment result.

[0011] Preferably, the step of real-time correction of the rheological compensation control command set based on the resistance state assessment result includes: when the resistance state assessment result indicates that the real-time stamping resistance is higher than the upper limit of the resistance threshold range, increasing the ultrasonic amplitude in the ultrasonic excitation parameters to reduce the deformation resistance of the sheet metal to be processed; when the resistance state assessment result indicates that the real-time stamping resistance is lower than the lower limit of the resistance threshold range, decreasing the ultrasonic amplitude in the ultrasonic excitation parameters to maintain the forming stability of the sheet metal to be processed; and when the resistance state assessment result indicates that the real-time stamping resistance is within the resistance threshold range, keeping the current rheological compensation control command set unchanged.

[0012] Preferably, the driving dynamic rheological compensation mold system performs a stamping operation on the sheet metal to be processed, including: responding to the piezoelectric driving parameters, controlling the segmented piezoelectric ceramic unit in the dynamic rheological compensation mold system to generate micro-displacement to change the local radius of curvature of the mold surface; responding to the ultrasonic excitation parameters, controlling the ultrasonic transducer set on the dynamic rheological compensation mold system to generate high-frequency vibration to induce dislocation slip inside the sheet metal to be processed.

[0013] Preferably, the method further includes: using the high-frequency vibration to perform in-situ stress relief treatment while the sheet material to be processed is being formed, so as to eliminate the work hardening stress inside the sheet material to be processed.

[0014] Compared with existing technologies, this method acquires real-time modulus data of the sheet material to be processed and constructs a target strain energy density distribution map, transforming the traditional static calculation mode based on geometric trajectory and empirical springback coefficient into a dynamic mapping based on energy dissipation gradient. This method utilizes online pre-stretching to obtain a real physical benchmark, effectively overcoming the problem in existing technologies that cannot cope with the modulus fluctuation between material batches due to reliance on standard manual values ​​or fixed empirical coefficients. This ensures that the deformation energy barrier parameter can accurately reflect the real rheological requirements of the sheet material on the forming path, thereby guaranteeing the physical consistency of the forming process. Attached Figure Description

[0015] The present invention will be further explained below with reference to the accompanying drawings and embodiments:

[0016] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0018] Example 1:

[0019] Please see Figure 1A method for stamping aerospace spiral springs includes: acquiring real-time modulus data of the sheet metal to be processed and the target geometric trajectory equation of the target spiral spring; performing energy mapping calculations on the target geometric trajectory equation to determine the target strain energy density distribution map, which characterizes the energy dissipation gradient of the sheet metal to be processed from the initial state to the formed state; determining the deformation energy barrier parameter at the current forming position based on the target strain energy density distribution map and real-time modulus data; calculating a rheological compensation control instruction set based on the deformation energy barrier parameter, wherein the rheological compensation control instruction set includes ultrasonic excitation parameters for adjusting the yield strength of the material and piezoelectric drive parameters for adjusting the local curvature of the die; and driving a dynamic rheological compensation die system to perform stamping operations on the sheet metal to be processed according to the rheological compensation control instruction set.

[0020] This embodiment details the core logic of mapping the forming process from geometric space to a thermodynamic energy field; the system executes a data acquisition step, where the real-time modulus data refers to the true Young's modulus of the sheet material to be processed under the current ambient temperature and batch conditions, which is obtained through online pre-stretching tests; the target geometric trajectory equation is derived from the CAD design data import.

[0021] The system defines a target strain energy density distribution map, which aims to transform the curvature change of the geometry into a gradient change of energy dissipation, characterizing the scalar field distribution of the plastic work required by the material at each point along the forming path. To concretely implement this transformation process and meet code-level reproducibility requirements, the system executes the following specific mapping operation steps: [The text then abruptly shifts to a different topic:] ...the target geometric trajectory equation... Perform parameterized solution to obtain the arc length along the trajectory. instantaneous geometric curvature function ;

[0022] Based on the plane strain assumption, a mapping operator from the geometric domain to the energy domain is constructed. The specific calculation formula is as follows:

[0023]

[0024] in, This represents the strain energy density value at that point in the distribution map, with the upper limit of integration. The numerical relationship between the strain integral interval and the geometric curvature was clarified. Let be the material constitutive function; by applying this operator to all discrete points on the trajectory, a complete energy dissipation gradient map is generated; the system calculates the deformation energy barrier parameter, which aims to quantify the work of pure plastic deformation and eliminate the influence of elastic potential energy. The calculation formula is as follows:

[0025]

[0026] in, The deformation energy barrier parameter is derived from calculations. In this embodiment, its physical meaning is defined as: the total strain of the material from its initial state to the current target state. The net plastic strain energy density accumulated and dissipated during the process; this parameter characterizes the energy barrier that a material needs to overcome to undergo permanent deformation, rather than just the instantaneous elastic limit energy that triggers yielding;

[0027] The total strain of the target is derived from the radius of curvature of the target's geometric trajectory equation at the current position. To ensure the dimensional consistency of the energy integral variable, this embodiment specifies its geometric mapping relationship as follows:

[0028]

[0029] in, The thickness of the sheet material; The instantaneous curvature of the trajectory at that point is called the radius of curvature. The reciprocal of is defined here as follows: convex is positive, concave is negative;

[0030] To ensure the accuracy of the data and address the issue that material constitutive model libraries are typically discrete, this embodiment employs a dynamic interpolation method based on temperature-strain rate coupling. The system pre-stores the basic stress-strain curves of the aerospace alloy at different standard temperatures (e.g., 20℃, 100℃, 200℃) and strain rates. During calculation, the system uses the strain rate corresponding to the current measured temperature and forming speed to synthesize the current instantaneous constitutive curve function through a bilinear interpolation algorithm. This allows for the acquisition of accurate stress values;

[0031] Real-time Young's modulus, obtained from previous steps;

[0032] Elastic recovery strain, originating from The calculation is based on the current stress state, and the specific calculation formula is as follows: This item represents the recoverable elastic deformation portion during unloading. Its corresponding elastic potential energy is deducted from the total work to ensure... The value corresponds precisely to the energy of irreversible plastic deformation;

[0033] Based on this, the system calculates the rheological compensation control instruction set, which is a set of signals that coordinate the control of the physical field, including ultrasonic excitation parameters for triggering the acousto-plastic effect and piezoelectric driving parameters for compensating for nonlinear rebound. The dynamic rheological compensation mold system responds to the instruction set by softening the material through ultrasonic vibration on the one hand, and pre-supporting the rebound amount by changing the mold curvature on the other hand.

[0034] This embodiment achieves a dimensional upgrade from geometric shape replication to energy flow control by constructing deformation energy barrier parameters and using them to calculate the rheological compensation control instruction set; by actively reducing the yield strength of materials using ultrasound, high-strength aerospace alloys exhibit low resistance characteristics similar to fluids during forming; and by fine-tuning the piezoelectric mold, the deadlock caused by excessive stamping to ensure accuracy, which leads to stress concentration, is broken, significantly improving the fatigue life and geometric consistency of the spring.

[0035] Obtaining real-time modulus data of the sheet material to be processed includes: performing online pre-stretching operation on the sheet material to be processed and collecting stress-strain response data; calculating the Young's modulus value of the sheet material to be processed based on the stress-strain response data, and determining the Young's modulus value as the real-time modulus data.

[0036] This embodiment details the physical acquisition path for real-time modulus data. A pre-tightening roller group is set at the stamping inlet to apply a small tension to the sheet metal, which is set to not exceed 10% of the yield strength to ensure the non-destructive nature of the test process. During this period, the system uses a high-precision force sensor and a laser displacement sensor to collect stress-strain response data. The system uses the finite difference method to calculate the Young's modulus value, and the calculation formula is as follows:

[0037]

[0038] in, Real-time Young's modulus, derived from calculations, physically represents the material's current ability to resist elastic deformation;

[0039] The stress increment during the pre-stretching process originates from data collected by the force sensor.

[0040] The corresponding strain increment comes from data collected by a laser displacement sensor;

[0041] This embodiment obtains real-time modulus data through online pre-stretching, effectively addressing performance fluctuations between batches of aerospace alloys and even at different locations within the same roll. This data provides the most realistic physical benchmark for subsequent energy barrier calculations and springback compensation, ensuring that the control model is adaptive to individual material differences and avoiding prediction biases caused by using standard manual values.

[0042] The energy mapping calculation of the target geometric trajectory equation is performed to determine the target strain energy density distribution map, including: constructing a path planning model based on the principle of minimum action, mapping the target geometric trajectory equation from Euclidean geometric space to the thermodynamic strain energy distribution model; calculating the optimal solution of energy dissipation of the sheet material to be processed along the forming path in the thermodynamic strain energy distribution model, and determining the target strain energy density distribution map.

[0043] This embodiment details the path planning logic based on energy minimization; the system constructs a thermodynamic strain energy distribution model, which uses spatial location as the independent variable and strain energy per unit volume as the dependent variable; to specifically realize the mapping from Euclidean geometric space to the thermodynamic strain energy distribution model, the system modifies the target geometric trajectory equation. Discretization is performed to generate a series of equally spaced control points distributed along the trajectory. ;

[0044] In this discretization process, the upper limit of the summation sign is calculated. This represents the total number of discrete control points, and its specific value depends on the total arc length of the target trajectory. With respect to the preset discretization precision, i.e., spatial step size Determined, that is In this embodiment, to ensure the accuracy of curvature calculation, Set to 0.5mm; for each control point The system is based on its geometric curvature Calculate the theoretical plastic work required to reach this curvature and use it as the energy potential node in the thermodynamic model. ;

[0045] Using the principle of least action, we seek a forming path that minimizes the total energy dissipation of the system; in this process, we define the energy functional of the system. As the objective function for optimization; to prevent the optimization result from converging to a non-target shape, such as the plane state with the lowest energy, due to simple energy minimization, this embodiment introduces a penalty term based on geometric constraints into the objective function, constructing a discrete objective function based on the penalty function method, as shown in the following formula:

[0046]

[0047] in, : Total energy functional including geometric constraints;

[0048] Plastic deformation power density is derived from calculations of material flow stress and strain rate.

[0049] Frictional power dissipation density, derived from the contact state model between the mold and the sheet metal;

[0050] Geometric fidelity penalty stiffness coefficient, which in this embodiment is defined as having physical units. The stiffness parameters are calculated as follows:

[0051]

[0052] in, As a dimensionless geometric fidelity weight, in this embodiment, based on the order-of-magnitude difference between the energy and geometric terms in the simulation test, and to ensure the priority of geometric fit, it is set to a weight through trial and error. ; For real-time Young's modulus, For the plate thickness. This coefficient converts geometric deviations into virtual elastic potential energy density, ensuring the uniformity of dimensions in the objective function, thus enabling the forced path points. Fit the target trajectory ;

[0053] The start and end times of the molding process;

[0054] The numerical solution process for this step is as follows: The system uses the discrete gradient descent algorithm to solve the energy functional. Perform optimization; define the state variable vector. These are the coordinates of discrete points along the forming path;

[0055] To ensure the partial derivatives in the gradient descent algorithm To ensure physical computability, this embodiment defines state variables. The discrete differential mapping relationship between the physical field quantities in the power density function and the path: for any point on the path Its local relative velocity Calculated using first-order backward difference, i.e. Its local equivalent forming strain rate Calculated based on the rate of change of curvature, i.e.

[0056]

[0057] To ensure the rigor of the algorithm, gradients are considered. For the specific calculation, this embodiment uses the chain rule decomposition: for any coordinate component Its gradient components are

[0058]

[0059] Among them, the geometric sensitivity term The three-point curvature formula is obtained by solving the analytical derivative of the three-point circular curvature formula, which is as follows:

[0060]

[0061] And explain This is a function of the triangle area. This construction of the analytical gradient eliminates the truncation error of the numerical difference.

[0062] Ensured that the algorithm was Convergence at a given precision; where time step It is a key parameter in discrete calculations, and its physical meaning is the time required for the sheet material to pass through two adjacent control points, determined by the set feed rate of the forming equipment. The decision is made, and the specific calculation formula is as follows: ;

[0063] In this embodiment, the feed rate Set to 10 mm / s; where, Depend on The reciprocal of the three-point fitted circle is determined; this explicit mapping relationship makes the objective function... Become about coordinate vectors Explicit functions;

[0064] The system calculates the objective function. Partial derivatives with respect to each coordinate point This includes the derivatives with respect to the energy and geometric penalty terms, and the path coordinates are iteratively updated according to the following formula:

[0065]

[0066] in, The learning rate is set to 0.01. This value is an empirical value selected based on the magnitude of the gradient, aiming to ensure smooth convergence of the iteration process without oscillations. In practical applications, it can be adjusted according to... The rate of change is dynamically adjusted within the interval [0.001, 0.1]. The iteration count is set to [number]; the iteration termination condition is set to [condition].

[0067]

[0068] in, The preset convergence threshold is set to [value]. J; Through this convergence path, the optimal strain energy density value at each point along the path is obtained, and then the target strain energy density distribution map is generated;

[0069] To ensure the computational accuracy and dimensional consistency of the above model, this embodiment further clarifies the specific calculation method for power density: plastic deformation power density The modified Hollomon model is used for calculation. To meet the requirements of power dimensions, the expression is as follows:

[0070]

[0071] in, To ensure the state variables in the above constitutive equations That is, equivalent plastic strain, which can be directly passed through geometric path points. To ensure variable traceability, this embodiment defines a mapping relationship between the variable and the local geometric curvature: This formula assumes that the strain distribution of the plate along the thickness direction conforms to the linear beam bending theory in the current infinitesimal segment; here The strength coefficient, The hardening index, For reference strain rate, This is the strain rate sensitivity coefficient; for the above material parameters, this embodiment calibrates them through standard materials mechanics experiments: Set as the experimental reference rate, such as ; , and By covering the same batch of plate samples at different strain rates... Uniaxial tensile tests were performed, and the obtained true stress-true strain data were fitted to the above constitutive equations.

[0072] To ensure that those skilled in the art can reproduce the simulation process, this embodiment provides a set of typical measured parameters for aerospace-grade 30CrMnSiA high-strength steel: strength coefficient. Hardening index Strain rate sensitivity coefficient ;

[0073] Frictional power dissipation density The dynamic Coulomb friction model is used for calculation, and the expression is as follows:

[0074]

[0075] in, The thickness parameter is introduced to represent the real-time thickness of the plate, in order to convert the frictional heat flux per unit area into the power density per unit volume. Thus, with plastic deformation power density Achieve dimensional matching and perform algebraic summation; where the friction coefficient is... The contact friction coefficient is measured under actual lubrication conditions using a Pin-on-Disc friction and wear testing machine. In this embodiment, the measured value is 0.1. Regarding the normal pressure in the formula... To avoid the inability to assign a value to this intermediate variable due to the lack of a contact mechanics model, which would violate the principle of variable tracing, this embodiment establishes an analytical estimation model based on the force equilibrium of bending micro-elements.

[0076] Given that the approximate theory of thin-walled containers is mainly applicable to structures with internal pressure expansion, and its direct application to contact stamping scenarios results in a physical incompatibility, this embodiment is modified to use a flexible cable / membrane contact mechanics model for description. Specifically, it considers that when the sheet metal is bent tightly against the mold surface, the resultant force component generated by the axial plastic tensile stress along the normal direction of curvature within its cross-section balances the reaction force of the mold. More specifically, it assumes that the sheet metal is in a state of complete plastic yield at the bending point, based on the radial force balance condition of the micro-element.

[0077]

[0078] normal force intensity With the current equivalent flow stress and local curvature ,in, They are positively correlated, and the calculation formula is:

[0079]

[0080] This formula maps contact pressure, which is difficult to measure directly, into known geometric variables. , by state variables Decisions, and material state variables The function makes the energy functional For state variables The calculation of the total derivative becomes possible, thus ensuring the numerical executability of the gradient descent algorithm;

[0081] Based on the deformation energy barrier parameter, the rheological compensation control instruction set is calculated, including: determining the target acousto-plastic softening amplitude required to reduce the yield strength of the sheet material at the current forming position according to the deformation energy barrier parameter; and determining the ultrasonic excitation parameters according to the target acousto-plastic softening amplitude, which include ultrasonic frequency and ultrasonic amplitude.

[0082] This embodiment details the inverse solution process of ultrasonic parameters; the system calculates the target acoustoplastic softening amplitude; this embodiment adopts a piecewise correction model based on the average energy density throughout the process to prevent the division-by-zero singularity problem when the initial stress is zero. The calculation formula is as follows:

[0083]

[0084] in, : Target stress reduction, in Pa, derived from calculation;

[0085] Deformation energy barrier parameter, in units of Pa represents the plastic work per unit volume required to reach the target state at the current position.

[0086] The total strain of the target is a dimensionless quantity, derived from the cumulative curvature calculation of the target's geometric trajectory equation at the current position. The total strain is used here instead of the step strain in order to convert the accumulated energy barrier into the average equivalent flow stress of the entire process.

[0087] The sound energy conversion efficiency coefficient is a dimensionless quantity with a value range of [0.3, 0.7]. It is derived from a prior acoustic plasticity calibration experiment on a standard sample of the same material.

[0088] : Calculate the stability threshold, which is set to [value] in this embodiment. This value is an empirical value determined based on the lower limit of the floating-point operation precision of the control system, and is used to prevent the value from diverging when the denominator approaches zero.

[0089] To ensure the numerical stability of subsequent ultrasonic amplitude calculations, this embodiment adds a logic saturation step: the calculated... It needs to be limited, that is To prevent the target softening range from exceeding the material's yield strength. This results in a negative input value for the logarithmic function;

[0090] The system determines the amplitude and frequency in the ultrasonic excitation parameters based on the target acoustoplastic softening amplitude:

[0091] Determining the ultrasonic amplitude: Using the acoustic plasticity effect model, the required ultrasonic amplitude is calculated backwards, as shown in the following formula:

[0092]

[0093] in, Ultrasonic amplitude, derived from calculation;

[0094] : Sound plasticity coefficient The source is the ultrasonic tensile calibration experiment conducted on standard samples of the same material in advance, and the relationship between stress reduction ratio and amplitude is fitted by fitting the curve. Obtaining the slope;

[0095] The static yield strength of a material is derived from its material properties.

[0096] Determination of ultrasonic frequency: To ensure efficient transmission of ultrasonic energy to the material to be processed, this embodiment employs dynamic impedance analysis. Before each forming step, the system performs a small-range frequency sweep (18kHz to 22kHz) on the mold-material coupling system. By analyzing the impedance spectrum, the minimum point of the impedance modulus is found, and the resonant frequency corresponding to this minimum point is determined. The current ultrasonic frequency has been determined.

[0097] Based on the deformation energy barrier parameter, the rheological compensation control instruction set is calculated, which also includes: predicting the nonlinear springback trend of the sheet material to be processed according to the deformation energy barrier parameter and real-time modulus data; calculating the curvature correction amount for the dynamic rheological compensation mold system according to the nonlinear springback trend, and converting the curvature correction amount into piezoelectric drive parameters.

[0098] This embodiment details the prediction and generation logic of piezoelectric drive parameters; the system uses a nonlinear springback model to predict the curvature of the sheet after unloading; considering that there is a nonlinear positive correlation between the unloading springback amount and the accumulated plastic work in the deep plastic deformation stage of high-strength alloys, and to avoid the complex tensor springback calculation affecting the response speed of real-time control, this embodiment establishes a semi-empirical prediction model based on energy equivalence, and the calculation formula is as follows:

[0099]

[0100] in, The predicted curvature after unloading is derived from calculations.

[0101] :Target loading curvature;

[0102] The bending lever arm, in this embodiment, is defined as the instantaneous radius of curvature of the target geometric trajectory at the current forming position, i.e. To avoid straight trajectory segments To prevent division by zero singularities, the system has a pre-defined computational protection logic: when At that time, it is directly determined to be in a state without bending, and let And subsequently ;

[0103] : Sheet thickness;

[0104] Real-time Young's modulus;

[0105] The system calculates the curvature correction and converts it into a piezoelectric driving voltage. This embodiment employs a precise driving model based on micro-displacement-bulge curvature mapping. This model is based on the longitudinal elongation of the piezoelectric stack lifting the flexible mold panel, thereby changing the geometric relationship of the local curvature. The corrected calculation formula is as follows:

[0106]

[0107] in, Piezoelectric driving voltage, in volts (V), derived from calculations;

[0108] Curvature difference to be compensated The unit is ;

[0109] The effective working chord length of the piezoelectric unit, in meters, corresponds to the physical width of the segmented mold unit, and is set to 0.01m in this embodiment.

[0110] The number of piezoelectric stack layers is a dimensionless quantity. In this embodiment, the PZT-5H standard stack actuator is selected, and this parameter is fixed at 200 to clearly calculate the total longitudinal displacement.

[0111] piezoelectric longitudinal strain constant, in units of For the PZT-5H material selected in this embodiment, its typical value is approximately ;

[0112] Formula derivation explanation: Based on the inverse piezoelectric effect, Stacked stacks at voltage The longitudinal elongation produced under the action is Assuming this minute displacement causes the flexible panel covering it to form a spherical protrusion, i.e., a bulge, according to geometric approximations, the height of the center of the spherical protrusion is... With curvature and chord length The relationship is By combining the two equations, we can obtain... Solving the above... The expression; this correction ensures that the control parameters are consistent with the actual physical mechanism of longitudinal elongation drive and surface bending deformation, achieving micron-level precise compensation for springback.

[0113] Example 2:

[0114] The method also includes: collecting real-time stamping resistance data during the stamping process; generating a resistance state assessment result based on the real-time stamping resistance data and a preset resistance threshold range; and making real-time corrections to the rheological compensation control instruction set based on the resistance state assessment result.

[0115] Based on the resistance state assessment results, the rheological compensation control command set is modified in real time, including: when the resistance state assessment results indicate that the real-time stamping resistance is higher than the upper limit of the resistance threshold range, the ultrasonic amplitude in the ultrasonic excitation parameters is increased to reduce the deformation resistance of the sheet metal to be processed; when the resistance state assessment results indicate that the real-time stamping resistance is lower than the lower limit of the resistance threshold range, the ultrasonic amplitude in the ultrasonic excitation parameters is decreased to maintain the forming stability of the sheet metal to be processed; when the resistance state assessment results indicate that the real-time stamping resistance is within the resistance threshold range, the current rheological compensation control command set remains unchanged.

[0116] This embodiment details the closed-loop control logic based on resistance feedback; real-time stamping resistance data is collected using a high-frequency piezoelectric force gauge installed on the mold base; the system compares this data with a preset resistance threshold range; regarding the specific source of the preset resistance threshold range, to ensure the integrity of the parameter definition, this embodiment uses virtual twin pre-simulation generation: before physical processing begins, the system calls the embedded explicit finite element solver, such as the LS-DYNA kernel, and loads the real-time Young's modulus obtained in Embodiment 1. constitutive models generated by interpolation The standard operating conditions are set, i.e., friction coefficient 0.1, no ultrasonic excitation;

[0117] When establishing the simulation environment using the explicit finite element solver, to prevent numerical oscillations from causing threshold calculation failures, this embodiment specifies the following contact and mesh parameters: The Belytschko-Tsay shell element algorithm is used, and the mesh size is set as follows: Define the contact type between the mold and the sheet metal as automatic single-sided contact, and set the contact penalty stiffness coefficient to [value missing]. The coefficient of kinetic friction is set to The time step is controlled by quality scaling. Order of magnitude; based on the above settings, an ideal shaping simulation of the target trajectory is performed, outputting the theoretical drag curve that varies with time. ;

[0118] Furthermore, the system defines the following threshold range: upper threshold. lower threshold The system executes a graded correction strategy: when the real-time stamping resistance is higher than the upper limit, the system determines that the material is severely work-hardened or lubricated, and then increases the ultrasonic amplitude to reduce the deformation resistance by utilizing a stronger acoustic-plastic effect; when the real-time stamping resistance is lower than the lower limit, the system determines that the material is excessively softened and may cause necking, and then decreases the ultrasonic amplitude to restore some of the material's strength; when the resistance is within the range, the system maintains the current instruction set.

[0119] The closed-loop feedback mechanism constructed in this embodiment acts as the system's sensory nerve; it can sense the resistance fluctuations macroscopically manifested by changes in the material's internal microstructure and adjust the energy field intensity in real time. This not only prevents mold chipping or product breakage due to excessive resistance but also prevents shape loss due to over-softening, significantly improving the robustness of the process under complex conditions. To transform the aforementioned qualitative adjustment strategy into a computer-executable control algorithm, this embodiment defines a specific discrete-time step control law: Let... The ultrasonic amplitude at time t is The sampling period is ,but Amplitude command at time Update using the following formula:

[0120] like If the value exceeds the upper threshold, incremental adjustment will be performed.

[0121]

[0122] in, For the proportional gain coefficient, the recommended initial setting value in this embodiment is... This coefficient is a control parameter obtained by performing a step drag disturbance test on the system and tuning it according to the Ziegler-Nichols rule; The base step size is set to This step size is based on the minimum displacement resolution of the piezoelectric actuator, which is 0.1. The engineering setting value is determined by multiplying by a safety factor of 5; This represents the physical limit of the transducer;

[0123] like If the value is below the lower threshold, a reduction adjustment will be performed:

[0124]

[0125] This specific mathematical expression establishes the input deviation. With output control quantity The explicit linear mapping relationship between them ensures the stability and convergence of the closed-loop control system.

[0126] Example 3:

[0127] The dynamic rheological compensation mold system is used to perform stamping operations on the sheet metal to be processed, including: in response to piezoelectric driving parameters, controlling the segmented piezoelectric ceramic unit in the dynamic rheological compensation mold system to generate micro-displacement to change the local radius of curvature of the mold surface; and in response to ultrasonic excitation parameters, controlling the ultrasonic transducer set on the dynamic rheological compensation mold system to generate high-frequency vibration to induce dislocation slip inside the sheet metal to be processed.

[0128] The method also includes: using high-frequency vibration to perform in-situ stress relief treatment while the sheet material is being formed, so as to eliminate the work hardening stress inside the sheet material.

[0129] This embodiment details the operating mechanism and additional effects of the hardware actuator; the system controls the segmented piezoelectric ceramic unit embedded below the mold forming surface; and addresses the issue of single scalar piezoelectric drive parameters calculated in previous steps. To address the spatial addressing problem of accurately mapping to a segmented piezoelectric ceramic unit matrix, this embodiment defines the following spatial weighted mapping algorithm:

[0130] Obtain position coordinates: Real-time reading of the coordinates of the current contact center point between the stamping head and the sheet metal. ;

[0131] Traversing the element matrix: For each piezoelectric element on the mold base Obtain its center geometric coordinates ;

[0132] Calculate Gaussian weights: Calculate activation weights based on the Euclidean distance between the element and the contact point. The formula is:

[0133]

[0134] in, The preset effective influence radius is set to 5mm. This radius value is determined by measuring the radial distance at which the deformation field decays to 5% of the center deformation by performing point load tests on the flexible skin using finite element simulation software.

[0135] Generate driving voltage: Calculate the actual applied voltage of each unit. ,in, The curvature correction voltage calculated in Example 5;

[0136] Through the above mapping algorithm, the system can respond to the piezoelectric driving parameters and drive a specific group of piezoelectric units below the current forming area to generate micro-displacement. By utilizing the continuity of high-strength flexible alloy skin, such as spring steel sheet with a thickness of 0.5mm to 2mm, the discrete displacement is transformed into a continuous and smooth curvature change on the mold surface, thereby constructing a non-uniform curvature distribution to counteract springback.

[0137] Simultaneously, the system drives an ultrasonic transducer via an amplitude transformer to couple high-frequency mechanical vibrations to the substrate to be processed. This vibration provides additional energy at the crystal lattice level, helping dislocations cross pinning points and thus inducing dislocation slip. For the in-situ stress relief treatment in this embodiment, to ensure the physical authenticity of the effect and distinguish it from ordinary acoustoplastic softening, this embodiment introduces a critical acoustic energy density determination mechanism: the system calculates the ultrasonic energy density transmitted to the substrate in real time. The unit is ;

[0138] Only when the calculated Exceeding the material's critical dislocation pinning energy density For aerospace spring steel, the default setting is... This threshold is a statistical average calculated from the activation energy required for dislocations within the alloy's crystal lattice to detach from the Cottrellatmosphere, determined through materials physics experiments. For other materials, this threshold can be obtained by measuring the activation energy required for dislocation detachment within the material's crystal lattice. Only when this threshold is reached does the system determine that it is currently in an effective stress-relief state and maintain this excitation for at least [duration missing]. Second;

[0139] If the threshold is not reached, the system will automatically reset the amplitude. The energy is compensated at 1.2 times the energy level; during this process, the high-frequency vibration energy causes the high-energy lattice atoms in the metastable state inside the material to jump to the low-energy state, thus achieving in-situ stress relief treatment.

[0140] This embodiment utilizes the in-situ stress relief function of ultrasound to combine molding and heat treatment into one process. This not only shortens the process chain, but more importantly, it eliminates the instantaneous residual stress peaks generated during the molding process, preventing the initiation of microcracks from a physical source. This results in the produced spiral springs having extremely high fatigue limits, solving the problem that traditional processes require long tempering times with limited effectiveness.

[0141] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for stamping and forming a spiral spring for aviation applications, characterized in that, The method includes: acquiring real-time modulus data of the sheet material to be processed and the target geometric trajectory equation of the target spiral spring; performing energy mapping calculation on the target geometric trajectory equation to determine the target strain energy density distribution map, which characterizes the energy dissipation gradient of the sheet material to be processed from the initial state to the formed state; determining the deformation energy barrier parameter at the current forming position based on the target strain energy density distribution map and the real-time modulus data; calculating a rheological compensation control instruction set based on the deformation energy barrier parameter, wherein the rheological compensation control instruction set includes ultrasonic excitation parameters for adjusting the yield strength of the material and piezoelectric drive parameters for adjusting the local curvature of the mold; and driving a dynamic rheological compensation mold system to perform a stamping forming operation on the sheet material to be processed according to the rheological compensation control instruction set. The step of obtaining the real-time modulus data of the sheet material to be processed includes: performing an online pre-stretching operation on the sheet material to be processed and collecting stress-strain response data; calculating the Young's modulus value of the sheet material to be processed based on the stress-strain response data, and determining the Young's modulus value as the real-time modulus data; The step of performing energy mapping calculations on the target geometric trajectory equation to determine the target strain energy density distribution map includes: constructing a path planning model based on the principle of minimum action, mapping the target geometric trajectory equation from Euclidean geometric space to a thermodynamic strain energy distribution model; calculating the optimal solution for energy dissipation of the sheet material to be processed along the forming path in the thermodynamic strain energy distribution model, and determining the target strain energy density distribution map. The step of calculating the rheological compensation control instruction set based on the deformation energy barrier parameter includes: determining, according to the deformation energy barrier parameter, the target acousto-plastic softening amplitude required to reduce the yield strength of the sheet material to be processed at the current forming position; and determining the ultrasonic excitation parameters, which include ultrasonic frequency and ultrasonic amplitude, according to the target acousto-plastic softening amplitude.

2. The stamping method for aerospace spiral springs according to claim 1, characterized in that, The step of calculating the rheological compensation control instruction set based on the deformation energy barrier parameter further includes: predicting the nonlinear springback trend of the sheet material to be processed according to the deformation energy barrier parameter and the real-time modulus data; calculating the curvature correction amount for the dynamic rheological compensation mold system according to the nonlinear springback trend, and converting the curvature correction amount into the piezoelectric drive parameter.

3. The stamping method for aerospace spiral springs according to claim 1, characterized in that, The method further includes: collecting real-time stamping resistance data during the stamping operation; generating a resistance state assessment result based on the real-time stamping resistance data and a preset resistance threshold range; and making real-time corrections to the rheological compensation control instruction set based on the resistance state assessment result.

4. The stamping method for aerospace spiral springs according to claim 3, characterized in that, The step of real-time correction of the rheological compensation control command set based on the resistance state assessment result includes: when the resistance state assessment result indicates that the real-time stamping resistance is higher than the upper limit of the resistance threshold range, increasing the ultrasonic amplitude in the ultrasonic excitation parameters to reduce the deformation resistance of the sheet metal to be processed; when the resistance state assessment result indicates that the real-time stamping resistance is lower than the lower limit of the resistance threshold range, decreasing the ultrasonic amplitude in the ultrasonic excitation parameters to maintain the forming stability of the sheet metal to be processed; and when the resistance state assessment result indicates that the real-time stamping resistance is within the resistance threshold range, keeping the current rheological compensation control command set unchanged.

5. The stamping method for aerospace spiral springs according to claim 1, characterized in that, The driving dynamic rheological compensation mold system performs a stamping operation on the sheet metal to be processed, including: responding to the piezoelectric driving parameters, controlling the segmented piezoelectric ceramic unit in the dynamic rheological compensation mold system to generate micro-displacement to change the local radius of curvature of the mold surface; responding to the ultrasonic excitation parameters, controlling the ultrasonic transducer set on the dynamic rheological compensation mold system to generate high-frequency vibration to induce dislocation slip inside the sheet metal to be processed.

6. The stamping method for aerospace spiral springs according to claim 5, characterized in that, The method further includes: using the high-frequency vibration to perform in-situ stress relief treatment while the sheet material to be processed is being formed, so as to eliminate the work hardening stress inside the sheet material to be processed.

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