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CN-121980837-A - Display backboard stamping process optimization method and system

CN121980837ACN 121980837 ACN121980837 ACN 121980837ACN-121980837-A

Abstract

The invention provides a method and a system for optimizing a stamping process of a display backboard, and relates to the technical field of process optimization. In the invention, multi-region differential meshing is implemented on a plate finite element model, fine meshes are adopted for a small curvature region and a large strain region with high strain, coarse meshes are adopted for a trimming allowance region, and medium meshes are adopted for the rest regions. The deformation behavior of the key region is accurately captured, and the reliability of simulation prediction is remarkably improved under the same computing resource. And then, carrying out reverse compensation iterative correction on the initial profile based on a rebound prediction result, quickly converging to obtain an optimized profile model, and directly controlling the source aiming at rebound errors, thereby greatly reducing the number of times and period of traditional experience-dependent test. The method realizes dynamic optimization and closed-loop control of the process window through the linkage of simulation and real-time sensing data, and effectively improves the molding quality and the production stability of the display backboard.

Inventors

  • HAN DING
  • CHEN BOBO
  • CHEN HOUYI

Assignees

  • 江苏金利美工业科技有限公司

Dates

Publication Date
20260505
Application Date
20251127

Claims (10)

  1. 1. The display backboard stamping process optimization method is characterized by comprising the following specific steps of: The method comprises the steps of 1, establishing a CAD model of a display backboard and an initial profile model of a stamping die, establishing a sheet material finite element model corresponding to the CAD model based on the CAD model, and carrying out multi-region differentiated grid division on the sheet material finite element model; Step 2, based on the rebound prediction result, performing reverse compensation correction on the initial profile model to obtain an optimized profile model; step 3, arranging a multiple sensing system in a stamping production line, wherein the multiple sensing system comprises a distributed pressure sensor, a visual sensor and a laser scanner; Step 4, performing trial stamping production, collecting real-time data through a multiple sensing system, wherein the real-time data comprises collecting partition blank pressing force and material inflow, comparing the real-time data with an ideal process window, and calculating the balance deviation of the material inflow; And 5, obtaining the flatness deviation of the display backboard after stamping forming, and correlating the flatness deviation with the partition blank holding force and the material inflow amount so as to update the correlation coefficient in the finite element analysis software and realize the continuous optimization of finite element analysis.
  2. 2. The method for optimizing a stamping process of a display back plate according to claim 1, wherein the performing the multi-region differentiated meshing specifically comprises: dividing the plate finite element model into at least three control areas, and independently setting grid division for each control area, wherein the method specifically comprises the following steps of: Preliminary region identification is carried out on a plate finite element model so as to automatically identify potential high-strain regions, and the method specifically comprises a small curvature region and a large-strain region: The method comprises the steps of identifying small curvature areas, carrying out mathematical discretization on a curved surface in contact with a plate in an initial profile model to generate a series of dense detection points, calculating the main curvature radius of each detection point, mapping all areas meeting the main curvature radius not more than a preset radius threshold value onto the plate finite element model, and marking the areas as first candidate areas; Performing primary formability simulation, extracting a pre-distribution cloud picture of plastic strain based on a plate finite element model, and marking all areas meeting the plastic strain not smaller than a preset shaping threshold as second candidate areas; dividing a key forming area according to the primary area identification result, namely taking a union set of the first candidate area and the second candidate area to define the key forming area; According to the design drawing of the stamping die, in the sheet finite element model, taking the contour line of the final part as the reference, defining a strip area obtained by the trimming width set by the outward offset process as a trimming allowance area, adopting a rough grid in the trimming allowance area to save calculation resources, namely setting the thickness of the sheet with the maximum unit size not smaller than five times; and defining a part of the sheet finite element model which does not belong to the key forming area and the trimming allowance area as a stable flowing area, and adopting a medium grid, namely, the thickness of the sheet with the maximum unit size ranging from three times to 5 times.
  3. 3. The method for optimizing a stamping process of a display back plate according to claim 1, wherein performing the reverse compensation correction specifically comprises: Extracting the coordinate variation of each grid node before and after rebound in the sheet finite element model from the rebound simulation result to form a rebound displacement field vector, namely a rebound prediction result; the displacement field vector is inverted by adopting a reverse compensation algorithm, and a compensation coefficient is introduced for adjustment, so that a reverse displacement field for compensating an initial profile model is obtained, and the mathematical expression is as follows: Wherein, the The modulus length of the displacement field vector is the magnitude of the rebound quantity, and the direction is the rebound direction; For the generated reverse displacement field; Is a compensation coefficient; applying the calculated rebound displacement field vector to a corresponding grid node of the initial profile model through a space mapping relation to generate a mould profile model geometrically subjected to first round of pre-deformation compensation; resetting and running punch forming and rebound simulation by taking the die profile model subjected to first round of pre-deformation compensation as a new analysis model, and calculating the deviation between the critical dimension of the virtual punch finished product obtained after compensation and the CAD model; if the deviation exceeds a preset tolerance zone, repeating the process to perform iterative compensation, wherein each iteration uses a die profile model generated after one round of pre-deformation compensation as input; And when the deviation between the critical dimension of the virtual stamping finished product and the CAD model is not more than a preset tolerance zone, determining the die profile model obtained by the current iteration as a final optimized profile model.
  4. 4. The method for optimizing a stamping process of a display back plate according to claim 1, wherein the multiple sensing system is specifically arranged as follows: The distributed pressure sensors are embedded into the middle points of the four opposite angles and the long edges of the blank holder in an annular array mode and are used for monitoring the pressure distribution of the contact surface of the blank holder and the plate in the stamping process; The visual sensor is aligned with the plate material at the edge of the female die manufactured by the optimized profile model, and the actual material inflow into the female die in the stamping process is calculated by capturing the displacement of the prefabricated grid mark points on the plate material; the laser scanner is positioned at the tail end of the stamping production line and is used for carrying out three-dimensional morphology scanning on the display backboard after molding and demolding to obtain three-dimensional point cloud data, and the three-dimensional point cloud data is used for calculating flatness deviation; Calibrating an ideal process window specifically comprises: And constructing a two-dimensional process parameter space by systematically adjusting partition blank holding force and material inflow, wherein the material inflow is realized by controlling the supply flow of the lubricant through regulating and controlling a proportional servo valve, and the relation is determined by the following lubrication model functional relation: Wherein, the For the inflow of material, For the supply flow rate of the lubrication system, To characterize the lubrication efficiency coefficient of the effectiveness of the lubricant, To characterize the system response coefficient for initial sensitivity of the system to lubrication, wherein, All are determined by calibration experiments aiming at specific dies, plates and lubricants; Is the basic inflow in the non-lubricated state; The method comprises the steps of measuring the flatness of a punched display backboard under each group of partition blank holder force and material inflow parameters by using a laser scanner, defining the flatness deviation, and determining an ideal process window as a region formed by all process parameter combinations meeting the flatness deviation not more than a preset flatness deviation threshold value, wherein the process parameter combinations comprise partition blank holder force and material inflow.
  5. 5. The method for optimizing a stamping process of a display back plate according to claim 1, wherein a material inflow balance criterion formula is established: Wherein, the In order to balance the deviation of the characteristic, And The inflow amounts of materials of the left flange and the right flange of the display backboard to be analyzed, which are measured by the visual sensor, respectively; Presetting an equilibrium threshold, and judging that the material flows unevenly when the equilibrium deviation is larger than the equilibrium threshold, wherein the control system performs at least one of the following operations: The partition blank holder force is adjusted, namely the partition blank holder force of the blank holder partition corresponding to the side with smaller inflow is reduced to reduce the constraint on the side material, or the partition blank holder force of the blank holder partition corresponding to the side with larger inflow is increased to inhibit the side material from flowing in too fast; The lubricant is adjusted by increasing the lubricant supply amount to the region corresponding to the smaller inflow side to promote the material flow on the side or by decreasing the lubricant supply amount to the region corresponding to the larger inflow side to suppress the material flow on the side.
  6. 6. A method of optimizing a stamping process for a display backplane according to claim 1, wherein the control system is provided with a priority logic: Judging whether the partition edge pressing force of the left side flange and the partition edge pressing force of the right side flange of the display backboard to be analyzed are unbalanced before when the balance deviation is larger than the balance threshold value, namely judging whether the absolute difference value of the partition edge pressing force of the left side flange and the partition edge pressing force of the right side flange is larger than a preset force deviation threshold value, if so, judging that the partition edge pressing force is unbalanced and is a main cause for uneven material flow, and preferentially executing partition edge pressing force adjustment; meanwhile, when the real-time data deviates from the ideal process window, the control system directly adjusts the partition edge pressing force or the supply quantity and distribution of the lubrication system according to the boundary value of the ideal process window, so that the real-time data returns to the ideal process window.
  7. 7. The method for optimizing a stamping process of a display back plate according to claim 1, wherein adjusting the zone edge pressing force comprises: The blank holder is divided into at least four independent control subareas, and each subarea is driven by a servo hydraulic cylinder or an electric cylinder; Dividing an independent blank holder force control range for each control partition based on an ideal process window, wherein the blank holder force control range is mapped from a set of all process parameter points of the ideal process window; The control system independently adjusts the output force of each servo hydraulic cylinder or each electric cylinder based on the real-time partition blank holder force value in each partition fed back by the distributed pressure sensor through a PID control algorithm, so that the partition blank holder force of each partition reaches a set value in an ideal process window; when the real-time partition edge pressing force collected by any partition continuously deviates from the control range of the edge pressing force, namely the continuous deviation time exceeds a preset time threshold, the control system is triggered to independently adjust the control partition.
  8. 8. The method of claim 4, wherein the adjusting of the supply and distribution of the lubrication system is achieved by a multi-nozzle lubrication system with independent control of the opening, closing and flow, and the control system changes the supply and distribution of the lubricant by dynamically adjusting the output flow of the nozzle in the corresponding control area according to the balance of the inflow of the material.
  9. 9. The method of claim 1, wherein modifying the correlation coefficients in the initial profile model comprises: A reference plane grid which coincides with the shape of the display backboard is predefined in a CAD model of the display backboard, and the grid is composed of a plurality of evenly distributed virtual sampling points; The method comprises the steps of obtaining three-dimensional point cloud data of a stamping forming backboard through a laser scanner, mapping the three-dimensional point cloud data onto a pre-defined reference plane grid through a coordinate transformation and data registration algorithm, searching the mapped three-dimensional point cloud data in a neighborhood of each virtual sampling point in the reference plane grid, taking an arithmetic average value of heights in the neighborhood as a height value of the virtual sampling point, and calculating the planeness deviation of the stamping forming backboard, wherein the calculation formula is as follows: Wherein, the Representing the flatness deviation, n is the number of virtual sampling points, For the height value of the i-th virtual sampling point, The average value of the height values of all the virtual sampling points is obtained; simultaneously, a plurality of groups of real-time data sequences of subarea blank holding force and material inflow and corresponding flatness deviation data collected in the same production batch are associated to form a training sample set for correcting an initial profile model; Inputting the training sample set into a parameter inverse algorithm, and reversely identifying a correlation coefficient in a finite element analysis model by taking the error between the minimum predicted flatness deviation and the calculated flatness deviation as a target, so that the error value of the predicted flatness deviation and the calculated flatness deviation is minimum, wherein the correlation coefficient at least comprises a material hardening coefficient and a friction coefficient; And updating the optimized material hardening coefficient and friction coefficient obtained in the parameter inverse algorithm into finite element analysis software, so as to realize continuous optimization of finite element analysis simulation.
  10. 10. A display back panel stamping process optimization system, characterized in that the display back panel stamping process optimization method system is used for realizing a display back panel stamping process optimization method according to any one of claims 1-9, comprising: the device comprises a model establishing and punching rebound simulation module, a plate finite element model establishing and punching rebound simulation module, a rebound prediction module and a rebound prediction module, wherein the model establishing and punching rebound simulation module is used for establishing a CAD model of a display backboard and an initial profile model of a punching die; the reverse compensation optimization module is used for carrying out reverse compensation correction on the initial profile model based on the rebound prediction result so as to obtain an optimized profile model; The system comprises an ideal process window calibration module, a control module and a control module, wherein the ideal process window calibration module is used for arranging a multiple sensing system in a stamping production line, and the multiple sensing system comprises a distributed pressure sensor, a visual sensor and a laser scanner; The process parameter self-adaptive regulation and control module is used for performing trial stamping production, collecting real-time data through the multiple sensing system, including collecting partition blank holder force and material inflow, comparing the real-time data with an ideal process window, and calculating the balance deviation of the material inflow; The quality feedback and model iteration module is used for obtaining the flatness deviation of the display backboard after stamping forming, and correlating the flatness deviation with the partition blank holding force and the material inflow amount so as to update the correlation coefficient in the finite element analysis software and realize the continuous optimization of the finite element analysis.

Description

Display backboard stamping process optimization method and system Technical Field The invention relates to the technical field of process optimization, in particular to a method and a system for optimizing a stamping process of a display backboard. Background The display backboard is used as a key structural member of the liquid crystal or OLED display module, and has the functions of bearing and protecting internal precise elements, and directly relates to the overall strength, heat dissipation performance and aesthetic appearance of the product. As displays move to larger, ultra-thin and full-screen directions, demands on the flatness, rigidity and dimensional accuracy of the back-plane are becoming increasingly stringent. At present, the display backboard is generally formed by stamping a metal plate (such as aluminum alloy and stainless steel) through a multi-station progressive die. During this process, there are various risks of defects, such as wrinkling, cracking, burrs, and rebound. Among these, rebound is the most dominant, difficult to control defect affecting the flatness and shape accuracy of the back plate. Due to release of elastic stress in the material after stamping forming, deviation occurs between the shape of the part after demoulding and the molded surface of the die, and deformation such as warping and twisting is generated. The deformation can directly lead to assembly gaps or stress between the backboard and the plastic middle frame and between the backboard and the screen module, abnormal sound and even screen breakage are caused, the backboard is not tightly attached to the rear shell, high-end texture of a product is affected, and the mounting hole position is deviated, so that the subsequent automatic assembly efficiency is affected. In the prior art, when CAE simulation is adopted, generally, globally uniform grid division parameters are adopted, or only software default settings are relied on. The method has obvious disadvantages that the whole model is divided into too thin for capturing the details of the key areas, so that the calculation resource waste and the efficiency are low, or too thick grids are used for pursuing the speed, so that the solving precision of key parts such as round corners, stretching ribs and the like is insufficient, and the rebound cannot be accurately predicted. This cut-in-one grid strategy is an important bottleneck that limits rebound simulation accuracy and efficiency. In addition, the rebound control in the prior art mainly depends on the experience of engineers, and is repeatedly adjusted in a mode of mold test and mold repair, so that the method has long period and high cost, depends on the personal skills of experienced masters, and has poor stability and replicability. The other thinking is that CAE software is adopted to conduct rebound prediction and compensation, but simulation accuracy is affected by factors such as a material model and boundary conditions, deviation exists between the simulation accuracy and actual production, and real-time disturbance caused by factors such as material performance fluctuation and lubrication condition change in the production process cannot be dealt with. Therefore, there is an urgent need for an integrated optimization method that can combine high-precision prediction with real-time control of a production process to stably and efficiently produce a high-precision display back plate. The above information disclosed in the background section is only for enhancement of understanding of the background of the disclosure and therefore it may include information that does not form the prior art that is already known to a person of ordinary skill in the art. Disclosure of Invention The invention aims to provide an optimal configuration method and device for a magnetic reactance type dynamic voltage restorer, which are used for solving the problems in the background technology. In order to achieve the above purpose, the present invention provides the following technical solutions: the display backboard stamping process optimization method specifically comprises the following steps: The method comprises the steps of 1, establishing a CAD model of a display backboard and an initial profile model of a stamping die, establishing a sheet material finite element model corresponding to the CAD model based on the CAD model, and carrying out multi-region differentiated grid division on the sheet material finite element model; Step 2, based on the rebound prediction result, performing reverse compensation correction on the initial profile model to obtain an optimized profile model; step 3, arranging a multiple sensing system in a stamping production line, wherein the multiple sensing system comprises a distributed pressure sensor, a visual sensor and a laser scanner; Step 4, performing trial stamping production, collecting real-time data through a multiple sensing system, wherein the real-time data comprises collect