Dynamic stress feedback stamping die for aluminum alloy left front door inner panel

Abstract

The application discloses a dynamic stress feedback stamping die for an aluminum alloy left front door inner plate, mainly relates to the aluminum alloy stamping technical field, is based on the stamping mode of the stamping die of the complex structure product, improves the stamping process, obtains the upper die action basic parameter through stamping simulation, identifies the stamping risk area and the stress transmission transition area, corresponds to divide the independent stress control unit and the buffer control unit, and supports the top assembly of the force sensing module for each unit, collects the stress data of each unit in real time, based on the stress difference of each area, dynamically corrects the up-down speed of the upper die in stages, synchronously adjusts the ejection force and the action time sequence of the top assembly, forms a full-process closed-loop control, can effectively block the stamping stress cross-region interference, balances the rebound stress release, and significantly reduces the forming defects such as cracking, collapse and warping of the thick-specification aluminum alloy plate stamping.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy stamping technology, specifically to a dynamic stress feedback stamping die for an aluminum alloy left front door inner panel. Background Technology

[0002] Due to the high ductility and high strength of aluminum alloys, they can be used as automotive body parts, often employing cold stamping forming technology, as described in publications CN118385397A and CN115889338A. The technology essentially uses hydraulic power, in conjunction with components in the upper / lower mold, to complete the product forming. Considering the product structure and power supply method, the following supplementary information is provided: Its power supply method is mainly trapezoidal, which requires providing instantaneous high stroke pressure to complete the overall deformation of the aluminum alloy, followed by pressure holding and shaping, and finally reset. Conventionally, the corresponding process data is mainly generated by model simulation calculation, such as the stroke and pressure data during pressing. However, considering the product structure (taking the left front door inner panel as an example), if the product structure is relatively complex and the product thickness is greater than 3mm, the deformation mode (deformation direction, deformation degree, and deformation area) of many regions will have obvious differences. Although the stamping die must be equipped with a series of supporting stress release methods such as ejection mechanism and positioning mechanism, the stress field of different regions of the whole raw material is complex, which causes the stress field of local regions to interfere with each other. Ultimately, it will still lead to abnormal deformation processes of different degrees in the product, such as large-arc bending or local collapse of the product after punching / pressing. In this regard, the present invention proposes a technical solution based on stamping technology. Summary of the Invention

[0003] The purpose of this invention is to provide a dynamic stress feedback stamping die for the inner panel of the left front door made of aluminum alloy, in order to solve the above-mentioned technical problems.

[0004] The objective of this invention can be achieved through the following technical solution: a dynamic stress feedback stamping die for an aluminum alloy left front door inner panel, comprising an upper die, a lower die, multiple forming blades, and a top assembly, using an aluminum alloy door inner panel forming system with a closed stamping die; The upper die is connected to the press drive system and can complete the downward die closing and upward reset actions. After the upper die and the lower die are closed, a forming cavity is formed that matches the contour of the target left front door inner panel. A mold core that fits perfectly with the inner contour of the product body is fixedly installed in the forming cavity of the lower die. Multiple sets of forming blades are detachably installed in the forming cavity of the upper mold. The installation position corresponds to the stamping risk area. The forming surface of each forming blade is completely matched with the outer contour of the product body of the corresponding stress control unit. In the forming cavity of the upper mold, the area without stamping risk is an integrated forming cavity that matches the contour of the product body. The top position assembly corresponds to the forming blade block. Each top position assembly includes a top position rod, a hydraulic elastic element, and a force sensor. The top position rod penetrates the forming blade block along the normal direction of the forming surface. Its upper end abuts against one end of the hydraulic elastic element, and the other end of the hydraulic elastic element is in close contact with the detection surface of the force sensor. The lower end of the top position rod is exposed outside the forming surface of the forming blade block in the initial state.

[0005] Furthermore, the force sensor is used to collect data on the normal and reverse forces experienced by the top rod after it contacts the plate, and includes the following steps: S1. Perform a full-process stamping simulation on the target left front door inner panel using stamping simulation software, including three stages: contact forming, pressure holding and shaping, and demolding and springback. Obtain the basic motion parameters of a single stamping action. Based on the simulation results, obtain the stamping risk area of ​​the product body and divide the stamping risk area into independent stress control units. Each stress control unit is configured with a forming blade block with a top assembly. Areas without stamping risk adopt an integrated forming cavity. S2. A force sensor is installed inside the top assembly. Through the force sensor inside the top assembly, the normal and reverse force data of the product body in each stress control unit during the entire stamping process are collected in real time, and the real-time stress data of the corresponding area is obtained. S3. Based on the basic motion parameters obtained from the simulation, and referring to the real-time stress data of multiple stress control units, calculate the stress change difference between regions, actively adjust and correct the upper mold travel speed, and synchronously adjust the ejection force and action sequence of each top assembly.

[0006] Furthermore, in step S1, the stress transfer transition area between adjacent stamping risk areas is located based on the simulation results, and the stress transfer transition area is divided into buffer control units. Each buffer control unit is equipped with a micro-instrument with a single-point top assembly.

[0007] Furthermore, the single-point top assembly also includes a top rod that is initially exposed on the micro-insert molding surface, as well as a matching force sensor, used to collect stress data in the transition area and block stress transmission across areas.

[0008] Furthermore, in step S1, the stress transfer transition area between adjacent stamping risk areas is located based on the simulation results. The stress transfer transition area is divided into buffer control units. Each buffer control unit is equipped with a micro-instrument, and the top assembly at this position is set as a single point.

[0009] Furthermore, the single-point top assembly is also equipped with a top rod and a force sensor that are initially exposed on the micro-insert molding surface, used to collect stress data in the transition area and block stress transmission across areas.

[0010] Furthermore, in step S3, the phased process of adjusting and correcting the travel speed of the upper mold is as follows: In the contact forming stage, the downward speed of the upper mold is corrected in real time according to the difference in contact impact stress in each region. When local stress overload or stress difference in multiple regions exceeds the threshold is detected, the downward speed of the upper mold is reduced. During the pressure holding and shaping stage, based on the stress concentration and stress transmission trend in each area, the upper mold closing position is adjusted slightly up and down at a controllable rate. This, combined with the top support action of the top assembly, counteracts localized stress concentration and prevents stress from being transmitted across areas. During the demolding and springback stage, the upper mold's upward reset rate is adjusted in real time based on the springback stress difference in each area. When excessive local springback stress or a springback stress difference across the entire area is detected, the upper mold's upward speed is reduced to balance the springback deformation across the entire product body.

[0011] Furthermore, it also includes a pre-calibration step before stamping, which uses the full-process stress data and product body size test results of the previous die as the calibration basis for this stamping, and corrects the basic speed curves of the upper die going down and going up, the initial exposure of the top rod, and the initial preload of the top assembly in advance, so as to achieve adaptive optimization between batches.

[0012] The present invention has the following beneficial effects: 1. Firstly, by dividing the stress control unit and buffer control unit, and cooperating with the force sensing structure of the top assembly, accurate stress acquisition is achieved throughout the entire cycle from sheet contact to demolding completion. In the three stages of contact molding, pressure holding and shaping, and demolding springback, the upper mold travel rate can be dynamically adjusted according to real-time stress data, and the ejection force and action sequence of the top assembly can be matched synchronously to regulate the plastic flow and stress distribution of the sheet, effectively blocking stress transmission and coupling interference across regions, and significantly reducing molding defects caused by local stress overload and stress concentration. At the same time, through differentiated upward speed control and top rod retraction sequence control, the springback stress release of the entire area is balanced to solve the product warping and dimensional deviation problems caused by uneven demolding springback, significantly improving the molding accuracy and molding quality of aluminum alloy left front door inner panels with a thickness of 3mm or more.

[0013] 2. Secondly, based on the basic motion parameters obtained from stamping simulation, and combined with the full-process stress data and product body size detection results of the previous stamping operation, the upper die speed curve, initial protrusion of the top rod, and pre-calibration of the pre-clamping force for this stamping are completed in advance. This effectively eliminates systematic errors caused by batch-to-batch mechanical property fluctuations in aluminum alloy sheets and improves the dimensional consistency of mass production. At the same time, the upper die speed is controlled by the linkage of stress overload coefficient and stress difference coefficient. When the stress is abnormal, the speed is accurately reduced to complete stress control. After the stress returns to the threshold, the reference speed is quickly restored. While ensuring the forming quality, the forming accuracy of the product body and the production efficiency of industrial continuous stamping are taken into account, which is suitable for the large-scale mass production needs of automotive door inner panels. Attached Figure Description

[0014] Figure 1 This is a structural diagram of the product body in a dynamic stress feedback stamping die for an aluminum alloy left front door inner panel proposed in this invention. Figure 2 This is a simplified schematic diagram showing the positions of the top assembly and the forming blade relative to the product body in this invention; Figure 3 This is a schematic diagram showing the division of the product body along its meridian in this invention; Figure 4 This is a schematic diagram showing the separation of the product body along its latitude lines in this invention.

[0015] In the diagram: 1. Product body; 2. Forming blade; 3. Top assembly. Detailed Implementation

[0016] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1: For the inner panel of the left front door of automobiles, which is mostly made of aluminum alloy sheet with a thickness of more than 3mm, the plastic flow state of the sheet, the distribution of internal stress field and the travel speed of the upper die are directly and strongly correlated during the cold stamping process. The downward speed of the upper die directly determines the magnitude of the impact load at the moment of contact between the sheet and the die and the flow rate of the material's plastic deformation. If the downward speed is too fast, it will cause local impact stress overload, and if it is too slow, it will lead to material strain aging and reduced production efficiency. The upward reset speed of the upper die directly determines the release rate and distribution uniformity of the springback stress of the sheet during demolding. An unreasonable upward speed will directly lead to uneven release of springback stress, causing product warping and dimensional deviations. During the stamping process, the travel speed of the upper die forms a strong coupling relationship with the internal stress field of the sheet metal. The dynamic change of the speed can directly regulate the stress distribution state of the sheet metal, which is the basic principle for achieving active stress control in this invention. The basic content of this invention is to use the basic action parameters of a single stamping obtained by stamping simulation software as a benchmark. In the actual stamping process, through real-time stress feedback from multiple independent stress control units, the stress change differences between different regions are calculated. Using this as a key parameter reference, the travel speed of the upper die descending and ascending reset processes is actively and continuously adjusted and corrected. That is, through dynamic matching of the speed, the plastic flow and stress distribution of the sheet are controlled, and the stress cross-regional transmission and coupling interference are blocked. Finally, the forming quality is accurately controlled in a single stamping process. Furthermore, by using the top rod exposed in the initial state of the forming blade 2, in conjunction with the force sensor, real-time, full-process stress acquisition is achieved. The top rod contacts the sheet metal before the mold cavity. The normal reverse force generated by the sheet metal on the top rod is linearly positively correlated with the forming stress inside the sheet metal in the corresponding area. By acquiring the real-time changes of this reverse force, the dynamic change process of the stress field in the corresponding area can be accurately reconstructed. This detection method can realize the full-cycle stress data acquisition from the moment the sheet metal contacts to the completion of demolding, providing a real-time and accurate data source for the dynamic correction of the upper mold travel speed. Because there is no unified standard for aluminum alloy door panel structure, and the corresponding stamping dies also lack standardized specifications, although the basic structure is roughly the same, the only differences lie in the structural shape / size, installation position, or the use of up-and-down stamping methods depending on the product shape. Therefore, this invention does not limit specific stamping dies, but focuses on... Figure 1 The product body shown in the image has undergone improvements in the overall stamping process. First, the entire stamping process of the target left front door inner panel is simulated using stamping simulation software (AF / DF). This part roughly simulates the possible stamping states of the product body 1 during the stamping process in advance, thereby obtaining the basic action parameters of a single stamping action, including the basic rate curve of the upper die descending and the basic rate curve of the upper die ascending and resetting, providing a benchmark for rate control. At the same time, based on the simulation results, the target area is divided, and an independent stress control unit and a matching top assembly 3 are set in the stamping risk area. Buffer control units are set in the stress transmission path of adjacent risk areas, providing a structural basis for multi-area stress acquisition and stress blocking. During actual stamping operation, based on the basic motion parameters obtained from simulation, the force sensor in the top assembly 3 collects the normal and reverse forces of multiple control areas in real time, converts them into real-time stress data of the corresponding areas, and calculates the stress change differences between different areas. Based on this, the travel speed of the upper die downward movement and the upward reset movement are actively and continuously adjusted and corrected in the three core stages of contact forming, pressure holding and shaping, and demolding and springback. Simultaneously, by coordinating the ejection force and action timing adjustment of the top assembly 3, the stress distribution of the sheet metal is controlled from the source through dynamic matching of the rate, blocking the cross-regional transmission and coupling interference of stress, and finally achieving active control of the stress field in a single stamping process, eliminating forming defects from the root, and taking into account both production efficiency and the forming quality of the product body 1. Specifically, taking a structure such as top positioning / positioning / pressing as an example (without obvious specification requirements, only related to function), the basic content of this invention is that the top positioning rod contacts the product body 1 before the cutting block, but when approaching or reaching the state of holding pressure and shaping, the top positioning rod is completely retracted into the cutting block, and finally the product body 1 is still formed by the cutting block.

[0018] Example 2: The dynamic stress feedback stamping die for the aluminum alloy left front door inner panel used in this example includes an upper die, a lower die, N sets of forming cutter blocks 2, M sets of micro inserts, N sets of top-position assemblies 3 corresponding to the forming cutters, M sets of single-point top-position assemblies 3 corresponding to the micro inserts, and a corresponding control module. N is the number of stamping risk areas, and M is the number of stress transfer transition areas. The following is a supplementary explanation: The main structure of the mold has an upper mold that is connected to the drive system of the stamping machine. Under the control of the drive system, it can complete the downward mold closing and upward reset actions. After the upper mold and the lower mold are closed, a forming cavity is formed that matches the contour of the target left front door inner panel. The rated volume of the forming cavity is denoted as V0. The mold core that is completely fitted to the inner contour of the product body 1 is fixedly installed in the forming cavity of the lower mold. The fit deviation between the forming surface of the mold core and the inner contour of the product body 1 does not exceed the preset threshold. The N-group forming cutter blocks 2 are detachably installed in the forming cavity of the upper die through a standardized interface. The installation position corresponds one-to-one with the N stamping risk areas identified by the stamping simulation. The forming surface of a single forming cutter block 2 is completely matched with the outer contour of the product body 1 of the corresponding stress control unit. The risk-free area in the upper die forming cavity adopts an integrated forming cavity that matches the contour of the product body 1. The M-group micro-inserts are installed in the stress transmission transition area, forming a physical barrier boundary for stress transmission together with the forming cutter blocks 2. First, let's supplement the stress feedback acquisition structure: it is essentially based on the top rod, hydraulic elastic component and force sensor in each top assembly 3, and the key is to use the specific value fed back by the force sensor as the stress feedback value. The top rod penetrates the forming blade 2 along the normal direction of the corresponding forming surface. Its upper end abuts against one end of the hydraulic elastic element, and the other end of the hydraulic elastic element is in close contact with the detection surface of the force sensor. The lower end of the top rod is exposed on the forming surface of the forming blade 2 in the initial state, and the initial exposure amount is denoted as L. The stiffness coefficient of the hydraulic elastic element is denoted as k, the rated compression stroke is denoted as S, and the sampling frequency of the force sensor is denoted as f. The normal and reverse forces acting on the top rod can be collected in real time, and the collected real-time force data is denoted as F. i (t); in i Let i be the sequence number of the stress control unit, i be a positive integer, t be the time variable of the stamping process, and k, S and f be treated as constants. Top assembly 3 (not single-point type) is used to collect stress data in the stress transfer transition region. Its internal structure is basically the same, and the collected real-time force data is denoted as F. j (t), j This is the sequence number of the buffer control unit; First, synchronously receive the F data collected by all force sensors. i (t), F j After preprocessing, data such as (t) are transmitted to the control module; The control module, as the assembly control terminal, is electrically connected to the press drive system, the hydraulic control modules of all top assemblies 3, and the force sensor. It generates rate correction commands based on real-time stress data and sends them to the press drive system to dynamically adjust the downward and upward travel speed of the upper die. The key to this embodiment lies in realizing the hardware linkage between real-time stress acquisition and upper mold speed control, providing a hardware foundation for stress feedback-based adjustment of the upper mold travel speed. At the same time, the multi-regional independent stress acquisition structure can accurately acquire the stress change differences in different regions, providing a complete and accurate data source for targeted speed correction, ensuring the pertinence and accuracy of subsequent speed correction.

[0019] Example 3: This example supplements the above description by explaining the specific implementation process: Based on the three-dimensional digital model of the target left front door inner panel (product body 1), a simulation model of the mold and sheet metal is constructed in the stamping simulation software. The mechanical property parameters of the sheet metal (yield strength σs, tensile strength σᵦ, hardening index n, thickness anisotropy coefficient r) and the mold structure parameters are input to complete the setting of the simulation boundary conditions. The above-mentioned mechanical property parameters are parameters that must be input in the simulation software. They belong to the physical properties of the material of product body 1 and are only related to the material itself. In this invention, they are used as constants. The key content of this section is to calculate the optimal stamping process parameters based on the goals of achieving the best forming quality and the highest production efficiency, thereby obtaining the basic motion parameters for a single stamping action. Specifically, this includes the following: The basic speed curve of the upper die descending is set as v0X(t), which represents the speed-time relationship of the upper die from the initial position to the mold closing and pressure holding position during the entire stroke. The upper die's upward reset base rate curve is set as v0S(t), which represents the full stroke rate-time relationship of the upper die resetting from the holding position to the initial position; The basic holding pressure and holding time during the pressure holding stage are part of the process parameter requirements. The control area is divided synchronously based on the simulation results: Based on the simulation results (data obtained from simulation software), the stamping risk area and stress transmission transition area are identified. The continuous stamping risk area is divided into independent stress control units, and the stress transmission transition area between adjacent risk areas is divided into buffer control units. The arrangement of forming blade 2, micro insert and top assembly 3 is completed accordingly. Based on the production data from the previous die, the basic parameters for this stamping process are pre-calibrated, including the following: Extract the full-process stress data of each control unit, the actual execution parameters of the upper mold speed, and the three-coordinate dimension detection results of the product body 1 during the previous production process to obtain the average deviation value Δσ between the actual stress and the simulation reference stress of the previous production, as well as the average dimension deviation value ΔD of the forming surface. Based on the above deviation values, the pre-calibration of the basic stamping rate curve is completed, resulting in the pre-calibrated downward rate curve v'0X(t) and upward rate curve v'0S(t). The calibration formula is as follows: v'0X(t)=v0X(t)×(1+α×Δσ+β×ΔD); v'0S(t)=v0S(t)×(1+γ×Δσ'+δ×ΔD'); Where Δσ' is the average springback stress deviation of the previous demolding stage, ΔD' is the average deviation of the springback-related dimensions, and α, β, γ, and δ are the corresponding influence coefficients, which are obtained through pre-experiment calibration.

[0020] Simultaneously complete the initial parameter calibration of top assembly 3: Based on the stress deviation of the previous die, calculate the adjustment amount ΔL of the initial exposure of the top rod in this stamping, and the adjustment amount ΔF of the initial preload of the hydraulic elastic component. The calculation formula is as follows: ΔL=Δσ×S0 / k ΔF=Δσ×S0 Wherein, S0 is the reference contact area between the top rod and the plate, which is a constant value in this embodiment, while k is the stiffness coefficient of the hydraulic elastic element, which is specifically related to the physical parameters of the hydraulic elastic element itself. To this end, the basic parameters are pre-calibrated using the production data from the previous batch, providing a more accurate benchmark for subsequent real-time dynamic corrections. This also improves the quality stability of the product body 1 across different production batches. Furthermore, based on the above, the three stages of contact forming, pressure holding and shaping, and demolding springback are highlighted: the contact forming and demolding springback stages are the most critical. Following a conventional stamping fluid pressure supply method, the stamping pressure increases linearly from contact forming to the pressure holding and shaping stage. The following analysis explains this: During the contact forming stage, the upper mold begins to descend according to the pre-calibrated downward base rate curve v'0X(t). After the top rod contacts the sheet material first, the force sensor synchronously collects the real-time reverse force F of each control unit. i (t), F j (t), and convert it into the forming stress σ of the corresponding region in real time. i (t), σ j (t), the conversion formula is: σ i (t)=F i (t) / S i S i To determine the contact area between the top rod and the plate, the following calculation and analysis process is performed: Single-area stress overload factor: η i (t)=σ i (t) / σ i0 , σ i0 For the simulation reference stress in this region, when η i When (t) > 1, it is determined that stress overload has occurred in this region; Multi-region stress difference coefficient: Δσ(t) = σmax(t) - σm i n(t), where σmax(t) is the real-time maximum stress value of all control units, σm i n(t) is the minimum value, and Δσ(t) reflects the uniformity of stress distribution throughout the region; Based on the two indicators mentioned above, the real-time correction of the downlink rate is completed. The formula for calculating the corrected real-time downlink rate vX(t) is as follows: vX(t)=v'0X(t)×[1-k1×(ηmax(t)-1)-k2×Δσ(t) / σ0] Where ηmax(t) is the maximum stress overload coefficient of all control units, σ0 is the average reference stress of the whole area, and k1 and k2 are rate correction coefficients, which are obtained through pre-experiment calibration and are also relative constants in this invention. Meanwhile, the rate correction and collaborative management execution process is as follows: When a local stress overload is detected, or the stress difference in multiple areas exceeds the preset threshold, the control module sends a correction command to the drive system of the press in real time, reduces the downward speed of the upper die, and controls the hydraulic elastic component of the top assembly 3 in the corresponding overload area to compress, thereby offsetting the local impact load through its own deformation. When the stress overload is eliminated and the stress difference across the entire region returns to the threshold range, the downward speed of the upper mold is gradually restored to the baseline curve. Demolding and Springback Stage: This stage involves the upper mold moving upwards from the mold-closing position back to its initial position after the holding pressure is completed. Stress feedback is used to correct the upward movement rate, balancing the release of springback stress across the entire area and preventing molding defects caused by uneven springback. The specific implementation process is as follows: After the pressure holding phase ends, the upper mold begins its upward reset according to the pre-calibrated upward base rate curve v'0S(t), and the force sensor continuously collects the real-time rebound reaction force FH from each control unit. i (t), converted into real-time rebound stress σH i (t), the control module calculates the springback stress distribution and springback trend of the entire area in real time.

[0021] Based on the differences in springback stress in different regions, the real-time correction of the upper mold's upward reset rate is achieved. The formula for calculating the corrected real-time upward rate vS(t) is as follows: vS(t)=v'0S(t)×[1-k4×(σHmax(t) / σH0-1)-k5×ΔσH(t) / σH0] Where σHmax(t) is the maximum real-time rebound stress of all control units, σH0 is the reference rebound stress of the region, ΔσH(t) is the range of rebound stress across the entire region, and k4 and k5 are the upward rate correction coefficients, which are obtained through pre-experiment calibration and are relative constants. The execution process of rate correction and collaborative management is as follows: When excessive rebound stress is detected in a local area or the difference in rebound stress across the entire area exceeds a preset threshold, the control module reduces the upper mold's upward reset rate in real time to slow down the release speed of the rebound stress. Synchronously execute differentiated top rod retraction timing control. For areas with high rebound stress, control the top rod to remain extended, delay for Δt time, and then retract it to continuously support the product body 1. The formula for calculating the delay time Δt is: Δt=c×(σH i(t)-σH0) c is the springback time influence coefficient, which is obtained through pre-experiment calibration. In areas with low springback stress, the top rod is controlled to retract synchronously with the upper mold. As the springback stress is gradually released and the difference in springback stress across the entire region returns to the threshold range, the upward movement rate of the upper mold is gradually restored to the baseline curve until demolding is completed.

[0022] By dynamically correcting the upper mold's upward reset rate through real-time feedback of springback stress, and in conjunction with differentiated top rod timing control, the springback stress of the sheet metal can be released smoothly and evenly. This solves the problem of uneven springback caused by the fixed upward speed in existing technologies, avoids springback defects such as overall warping and dimensional deviations of the product body 1, significantly improves the dimensional accuracy of the product body 1, and also takes demolding efficiency into account, so as not to cause excessive extension of the production cycle due to springback control.

[0023] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A dynamic stress feedback stamping die for an aluminum alloy left front door inner panel, comprising an upper die, a lower die, multiple forming blades (2), and a top assembly (3), characterized in that, An aluminum alloy door inner panel forming system using a closed stamping die; The upper mold is connected to the press drive system and can complete the downward mold closing and upward reset actions. After the upper mold and the lower mold are closed, a forming cavity matching the contour of the target left front door inner panel is formed. The forming cavity of the lower mold is fixedly installed with a mold core that is completely fitted to the inner contour of the product body (1). Multiple sets of forming blades (2) are detachably installed in the forming cavity of the upper mold. The installation position corresponds to the stamping risk area. The forming surface of each forming blade (2) is completely matched with the outer contour of the product body (1) of the corresponding stress control unit. In the forming cavity of the upper mold, the area without stamping risk is an integral forming cavity that matches the contour of the product body (1). The top assembly (3) corresponds to the forming blade (2). Each top assembly (3) includes a top rod, a hydraulic elastic element, and a force sensor. The top rod passes through the forming blade (2) along the normal direction of the forming surface. Its upper end abuts against one end of the hydraulic elastic element, and the other end of the hydraulic elastic element is in close contact with the detection surface of the force sensor. The lower end of the top rod is exposed outside the forming surface of the forming blade (2) in the initial state.

2. The dynamic stress feedback stamping die for the aluminum alloy left front door inner panel according to claim 1, characterized in that, The force sensor is used to collect data on the normal and reverse forces experienced by the top rod after it contacts the plate, and includes the following steps: S1. The target left front door inner panel is subjected to full-process stamping simulation by stamping simulation software, including three stages: contact forming, pressure holding and shaping and demolding and springback. The basic action parameters of a single stamping action are obtained. The stamping risk area of ​​the product body (1) is obtained according to the simulation results. The stamping risk area is divided into independent stress control units. Each stress control unit is configured with a forming blade (2) with a top assembly (3). The area without stamping risk adopts an integrated forming cavity. S2. A force sensor is installed inside the top assembly (3). Through the force sensor inside the top assembly (3), the normal and reverse force data of the product body (1) in each stress control unit during the entire stamping process are collected in real time, and the real-time stress data of the corresponding area is obtained. S3. Based on the basic motion parameters obtained from the simulation, and referring to the real-time stress data of multiple stress control units, calculate the stress change difference between regions, actively adjust and correct the upper mold travel speed, and simultaneously adjust the ejection force and action sequence of each top assembly (3).

3. The dynamic stress feedback stamping die for the inner panel of the left front door of aluminum alloy according to claim 2, characterized in that, In step S1, the stress transfer transition area between adjacent stamping risk areas is located according to the simulation results, and the stress transfer transition area is divided into buffer control units. Each buffer control unit is provided with a micro insert with a single-point top assembly (3).

4. The dynamic stress feedback stamping die for the inner panel of the left front door of aluminum alloy according to claim 3, characterized in that, The single-point top assembly (3) is also equipped with a top rod that is initially exposed on the micro-instrument molding surface, as well as a matching force sensor, which is used to collect stress data in the transition area and block stress transmission across the area.

5. The dynamic stress feedback stamping die for the inner panel of the left front door of aluminum alloy according to claim 2, characterized in that, In step S1, the stress transfer transition area between adjacent stamping risk areas is located according to the simulation results. The stress transfer transition area is divided into buffer control units. Each buffer control unit is equipped with a micro-instrument, and the top assembly (3) at this position is set as a single point.

6. The dynamic stress feedback stamping die for the inner panel of the left front door of aluminum alloy according to claim 5, characterized in that, The single-point top assembly (3) is also equipped with a top rod and a force sensor that are initially exposed on the micro-instrument molding surface, which are used to collect stress data in the transition area and block stress transmission across the area.

7. The dynamic stress feedback stamping die for the inner panel of the left front door of aluminum alloy according to claim 2, characterized in that, In step S3, the phased processing of adjusting and correcting the travel speed of the upper mold is as follows: In the contact forming stage, the downward speed of the upper mold is corrected in real time according to the difference in contact impact stress in each region. When local stress overload or stress difference in multiple regions exceeds the threshold is detected, the downward speed of the upper mold is reduced.

8. The dynamic stress feedback stamping die for the inner panel of the left front door of aluminum alloy according to claim 7, characterized in that, During the pressure holding and shaping stage, the upper mold closing position is adjusted slightly up and down at a controllable rate according to the stress concentration and stress transmission trend in each area. This is combined with the top support action of the top assembly (3) to offset local concentrated stress and block stress transmission across areas.

9. The dynamic stress feedback stamping die for the inner panel of the left front door of aluminum alloy according to claim 8, characterized in that, During the demolding and springback stage, the upper mold's upward reset rate is adjusted in real time according to the springback stress difference in each region. When the local springback stress is detected to be too large or the springback stress difference in the whole region exceeds the threshold, the upper mold's upward speed is reduced to balance the springback deformation of the entire product body (1).

10. The dynamic stress feedback stamping die for the inner panel of the left front door of aluminum alloy according to claim 2, characterized in that, It also includes a pre-calibration step before stamping, using the full-process stress data of the previous die and the product body (1) size detection results as the calibration basis for this stamping, and correcting the basic speed curves of the upper die going down and going up, the initial exposure of the top rod, and the initial preload of the top assembly (3) in advance to achieve adaptive optimization between batches.

Images