A double-flanged stamping integrated lightweight backboard and a sorting system thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 广东省顺为光电有限公司
- Filing Date
- 2026-04-21
- Publication Date
- 2026-07-14
Smart Images
Figure CN122377947A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of backplate design and sorting, specifically a lightweight backplate integrally formed by double-folded stamping and its sorting system. Background Technology
[0002] Metal backplates used in existing display devices, backlight modules, smart home devices, and some industrial control equipment are typically formed from sheet metal parts through processes such as blanking, punching, bending, and shaping, serving to achieve load-bearing, installation, and protection functions. Existing backplate structures are mostly planar edge structures or single-folded edge structures. When increased overall rigidity is required, it is usually achieved by increasing the sheet thickness, adding local flanges, or adding connection processes. However, these solutions still have certain shortcomings in practical applications: for larger backplates, the reinforcing effect of planar edges or single-folded edges on the periphery is limited. After the sheet is thinned, the edges are prone to twisting, warping, or local deformation, thus affecting the flatness of the entire panel, assembly stability, and reliability. Simply increasing the sheet thickness to improve strength leads to increased material usage, increased overall panel weight, and increased stamping load, which is not conducive to lightweighting and cost reduction requirements. At the same time, multi-process forming or additional connection methods may also bring problems such as process complexity, error accumulation, and difficulty in controlling forming consistency. Therefore, how to ensure good structural strength and torsional resistance at the edges of the back panel while reducing the thickness of the sheet metal, and how to balance molding consistency and manufacturing efficiency, remains a technical problem that needs to be solved in this field.
[0003] Furthermore, as backplate products develop towards lightweighting, double-folded edges, and one-piece molding, the requirements for online inspection and sorting after molding are also increasing accordingly. Existing sorting solutions typically identify the overall outline, hole positions, dimensions, or general appearance defects of ordinary panels. There is a lack of dedicated sorting systems for backplates with double-folded reinforced structures, corner transition structures, and edge avoidance structures. In particular, there is a lack of a sorting solution that can identify and determine the transition molding relationship between the corner transition section and the edge avoidance sections on both sides. Therefore, it is difficult to meet the need for consistent corner molding sorting of this type of backplate. Summary of the Invention
[0004] The purpose of this invention is to provide a lightweight backplate integrally formed by double-folded stamping and its sorting system, so as to solve the technical problems mentioned in the background art.
[0005] Based on the above ideas, the present invention provides the following technical solution:
[0006] A lightweight backplate integrally formed by double-folded stamping includes:
[0007] The back panel includes a back panel body, at least a portion of which has a double-folded edge reinforcement. The double-folded edge reinforcement is integrally formed by at least two stamping and bending processes from the edge of the back panel body, and is configured as a double-folded edge structure extending along the periphery of the back panel body to improve the structural strength and torsional resistance of the edge portion of the back panel body.
[0008] Preferably, the double-folded edge reinforcement is continuously provided along at least two adjacent side edges of the back plate body.
[0009] Preferably, the double-folded edge reinforcements on adjacent side edges are connected at corresponding corners by corner transition portions, which are located between the two adjacent side edges and form a rounded corner transition structure.
[0010] Preferably, the double-folded edge reinforcements on both sides of the corner transition portion are respectively provided with a closing clearance section. The closing clearance section cooperates with the corner transition portion so that the double-folded edge reinforcements on the adjacent two sides form a transition connection structure with intervals in the corner area.
[0011] Preferably, the end of the double-folded edge reinforcing part is provided with an end closing part, which is formed by folding back the end of the double-folded edge reinforcing part.
[0012] Preferably, the back plate body and the double-folded edge reinforcement are integrally stamped from the same thin metal sheet without welding, and the thin metal sheet is a galvanized steel sheet with a thickness of 0.5mm.
[0013] A sorting system for sorting the aforementioned lightweight backplate formed by double-folded stamping, comprising:
[0014] The conveying and positioning unit is used to convey the backplate to be sorted and position the corner area of the backplate to the detection station; the attitude correction unit is used to establish an angle bisector reference axis based on the edge contours of the adjacent two sides of the backplate body and to normalize the attitude of the corner area.
[0015] The image acquisition unit is used to acquire corner images including the double-folded edge reinforcement, the corner transition section, and the two side closing avoidance sections;
[0016] A contour extraction unit is used to extract the corner transition contour and the closing avoidance contour located on both sides of the corner transition portion from the corner image.
[0017] The transition continuity calculation unit is used to calculate the transition continuity index based on the effective length of the two side closing avoidance sections and the curvature undulation degree of the corner transition profile, so as to characterize the degree of continuous forming between the corner transition section and the two side closing avoidance sections.
[0018] The closing coordination degree calculation unit is used to calculate the closing coordination degree index based on the effective length of the closing avoidance sections on both sides and the degree of mirror deviation of the closing avoidance contours on both sides relative to the angle bisector reference axis, so as to characterize the degree of symmetrical coordination between the closing avoidance sections on both sides and the corner transition section.
[0019] The sorting execution unit is used to generate a corner transition forming consistency evaluation quantity based on the transition continuity index and the corner finishing coordination index, and to control the sorting mechanism to sort the back plate into qualified parts, rework parts or rejected parts based on the corner transition forming consistency evaluation quantity.
[0020] Preferably, the transition continuity calculation unit is used to determine the transition continuity index based on the effective length coordination of the avoidance sections on both sides of the corner transition section and the curvature fluctuation of the corner transition profile.
[0021] Among them, the effective length coordination degree of the two-sided closing avoidance section is used to reflect the matching state of the two-sided closing avoidance section in length, and the curvature fluctuation degree of the corner transition profile is used to reflect the smoothness of the curvature change of the corner transition profile along the extension direction.
[0022] The curvature fluctuation is obtained by statistically analyzing the curvature changes at adjacent sampling points on the corner transition profile, and then normalized by combining the reference curvature of the corner transition.
[0023] The closer the effective lengths of the two side closing clearance sections are and the smaller the curvature fluctuation of the corner transition profile, the greater the transition continuity index.
[0024] Preferably, the corner transition coordination calculation unit is used to determine the corner transition coordination index based on the effective length coordination of the corner transition avoidance sections on both sides and the mirror deviation of the corner transition avoidance contours on both sides relative to the angle bisector reference axis.
[0025] The degree of mirror deviation of the two sides of the narrowing avoidance contour relative to the angle bisector reference axis is obtained by comparing the mirror position of the sampling point of the narrowing avoidance contour on one side of the angle bisector reference axis with the corresponding sampling point of the narrowing avoidance contour on the other side, and then normalizing it in combination with the diagonal reference length of the corner detection area.
[0026] The closer the effective lengths of the two closing clearance sections are and the smaller the mirror deviation of the two closing clearance contours, the greater the closing coordination index.
[0027] Preferably, the sorting execution unit is used to generate the corner transition forming consistency evaluation quantity based on the coordination degree of the transition continuity index and the closing coordination index when both sides of the closing avoidance section are effectively identified and their effective lengths are both greater than zero.
[0028] The corner transition molding consistency evaluation quantity is used to comprehensively reflect the continuous molding level between the corner transition section and the two side closing avoidance sections, as well as the symmetrical coordination level between the two side closing avoidance sections.
[0029] When both the transition continuity index and the closing coordination index are large and the difference between them is small, the corner transition forming consistency evaluation value increases; when either the transition continuity index or the closing coordination index is small or the difference between them increases, the corner transition forming consistency evaluation value decreases.
[0030] The sorting execution unit is further configured to compare the corner transition forming consistency evaluation quantity with a preset sorting threshold. When the corner transition forming consistency evaluation quantity is not lower than the first threshold, it is determined to be a qualified part; when the corner transition forming consistency evaluation quantity is lower than the first threshold but not lower than the second threshold, it is determined to be a rework part; when the corner transition forming consistency evaluation quantity is lower than the second threshold, it is determined to be a rejected part, wherein the first threshold is greater than the second threshold.
[0031] The technical solution of the present invention may include the following beneficial effects:
[0032] The lightweight backplate, formed by double-folded stamping, features double-folded reinforcements around its perimeter, creating a continuous reinforcing structure that enhances overall rigidity and torsional resistance. Corner transition sections with tapered clearance sections on either side reduce forming interference and stress concentration in the corner areas, improving structural integrity and forming consistency. End tapering enhances the integrity of the double-folded reinforcements, improving edge safety and localized reinforcement. Using 0.5mm galvanized steel sheet in conjunction with a single stamping process reduces material usage while maintaining corrosion resistance and forming efficiency. This design achieves a 37.5% reduction in raw material thickness while still improving product strength and torsional resistance, and eliminates the need for subsequent electroplating and welding processes.
[0033] A further sorting system is designed for separating the aforementioned lightweight double-folded stamped unibody backplates. This system performs location acquisition, contour extraction, and consistency evaluation on the corner areas of the backplates, focusing on identifying the transitional forming state between the corner transition and the side end avoidance sections. This allows for the effective identification of subtle forming deviations that are difficult to distinguish accurately using conventional sorting methods. Compared to detection methods based on the overall outer contour or a single size threshold, this sorting system more specifically reflects the continuous forming degree of the double-folded structure in the corner area and the coordinated state of the side end avoidance sections. This improves the sorting accuracy of qualified parts, rework parts, and rejected parts, reduces misjudgments and omissions caused by abnormal corner transitions, inconsistent end avoidance, or local forming fluctuations, and further ensures the structural consistency and product quality stability of the lightweight double-folded stamped unibody backplates during mass production. Attached Figure Description
[0034] Figure 1 This is a schematic diagram of the overall structure of a lightweight backplate integrally formed by double-folded stamping according to the present invention.
[0035] Figure 2 This is a partial structural diagram of the double-folded edge reinforcement in the corner region of the present invention.
[0036] Figure 3 This is a partial structural diagram of the double-folded edge reinforcement in the end region of the present invention.
[0037] Figure 4 This is a system block diagram of a sorting system according to the present invention.
[0038] Figure 5 The following are the working steps of a sorting system according to the present invention.
[0039] In the diagram: 1. Back panel body; 2. Double-folded edge reinforcement; 21. Corner transition section; 22. Edge closing section; 23. End closing section. Detailed Implementation
[0040] Example 1
[0041] like Figures 1 to 3As shown, this embodiment provides a lightweight backplate integrally formed by double-folded stamping, including a backplate body 1. The backplate body 1 is generally plate-shaped, and its main planar area is used to support and install related components. Mounting holes, positioning holes, heat dissipation holes, and local functional areas can be formed on the main planar area according to the assembly requirements of the whole machine. At least a portion of the periphery of the backplate body 1 is provided with a double-folded reinforcing part 2. The double-folded reinforcing part 2 is integrally formed by stamping and bending the edge of the backplate body 1 at least twice, and extends along the periphery of the backplate body 1, thereby forming a double-folded edge structure with a folded edge at the periphery of the backplate. This structure is different from ordinary straight edges or single-folded edges, and can improve the structural strength, local rigidity, and overall torsional resistance of the edge part under relatively thin plate thickness conditions.
[0042] Furthermore, the double-folded edge reinforcement 2 is continuously provided along at least two adjacent side edges of the back plate body 1 to form a continuous edge reinforcement path on the outer periphery of the back plate. For metal back plates that are large in size and require flatness, assembly stability and resistance to deformation, the continuous double-folded edge reinforcement structure helps to reduce edge warping, local collapse and overall twisting. Figure 2 The diagram shows a partial structure of the corner region. The double-folded edge reinforcements 2 on adjacent sides are connected at the corresponding corners via corner transition sections 21. The corner transition sections 21 are located between the two adjacent sides, forming a rounded corner transition structure. By providing the corner transition sections 21, the double-folded edge reinforcements 2 on adjacent sides can achieve a smooth connection in the corner region, avoiding abrupt corner folds and improving the stress continuity and molding integrity of the corner region. The double-folded edge reinforcements 2 on both sides of the corner transition sections 21 are respectively provided with tapering and avoidance sections 22. These tapering and avoidance sections 22 are positioned near the corners, allowing the double-folded edge reinforcements 2 to form tapering and avoidance sections before entering the corner region, and completing the connection through the corner transition sections 21. This reduces material stacking, molding interference, and local stress concentration near the corners, improving corner molding accuracy and appearance consistency.
[0043] like Figure 3 As shown, the end of the double-folded edge reinforcement 2 is provided with an end taper 23. The end taper 23 is formed by folding back the end of the double-folded edge reinforcement 2, so that the double-folded edge structure forms a relatively complete end shape in the end area. By providing the end taper 23, the formation of exposed sharp edges or irregular breaks at the end of the double-folded edge structure can be avoided, improving the integrity and edge safety of the end area, and ensuring that the double-folded edge reinforcement 2 maintains a continuous reinforcement effect at the end position.
[0044] In this embodiment, the back plate body 1 and the double-folded edge reinforcing part 2 are integrally stamped from the same thin metal sheet without welding. The thin metal sheet is a 0.5mm thick galvanized steel sheet, which can be SGCC, with a double-sided galvanizing amount of not less than 45g / ㎡. When the raw materials arrive at the factory, the thickness tolerance, coating adhesion, substrate flatness, and tensile strength of the sheet are inspected. The thickness tolerance is controlled to be ±0.02mm, the coating adhesion is not less than 5B, the substrate flatness is not greater than 0.4mm / m, and the tensile strength is not less than 320MPa. By adopting the above material route, on the one hand, the thickness of the sheet and the amount of material used can be reduced, and on the other hand, the galvanized layer can be used to improve the corrosion resistance and ensure the adaptability of subsequent stamping and bending forming.
[0045] The aforementioned lightweight backplate can be integrally stamped using a servo press and precision progressive dies. The progressive die is configured with 7 to 9 steps, integrating blanking, punching, pre-bending, final bending, shaping, and trimming functions into a single die system. The stations related to double-folding use a movable rocker block structure to reduce relative sliding friction between the die and the sheet metal and achieve one-step double bending. The double-folding cavity tolerance is controlled at ±0.01mm, the inner corner radius of the fold is R=0.5mm, and the rocker block movement accuracy is controlled at ±0.005mm. Before the raw material enters the die, the sheet coil is unrolled and leveled by an uncoiler and a leveler to eliminate warping and internal stress. The leveling accuracy is controlled to be no greater than 0.1mm / m. Online cleaning rollers remove oil and zinc powder residue from the sheet surface to reduce the risk of stamping sticking and surface scratches.
[0046] In the specific forming process, the servo press, in conjunction with the progressive die, sequentially completes the backplate blank blanking, hole punching, edge pre-bending, double-edge final bending, and shaping. The blanking station is used to precisely cut the backplate blank; the punching station is used to form mounting holes, heat dissipation holes, and positioning holes; the pre-bending station bends the edges to 45° to allow for the final bending allowance; the final bending station closes the double edges to 90°; and the shaping station corrects springback and ensures flatness and edge perpendicularity. The stamping speed is controlled at 80 to 120 times / minute, the bending force is no more than 300kN, the double-edge overlap is no more than 0.03mm, and the formed double-edge area is free of plating peeling, wrinkles, and cracks. Through the above process path, the backplate body 1, double-edge reinforcement 2, corner transition 21, end relief section 22, and end end closing section 23 can all be integrally formed during continuous stamping without the need for separate welding.
[0047] For common process issues during the double-folded integrated forming process, targeted controls can be implemented. For galvanized layer scratches, a one-step double bending process using a movable swing block is employed, with hard chrome plating on the die surface. Simultaneously, stamping oil suitable for zinc-coated sheets is added to reduce relative sliding damage between the die and the sheet during bending. For springback issues after bending 0.5mm thin sheets, a servo press is used for segmented pressure holding, with a holding time of 0.2s, and a springback compensation of 0.05mm to 0.1mm is set in the progressive die. For cumulative dimensional errors caused by multi-stage positioning, a progressive die for integrated positioning is used, with a servo system compensating for feeding errors in real time, ensuring positioning accuracy is controlled within ±0.005mm. Through these process controls, the forming consistency and product stability of the double-folded structure can be improved.
[0048] After molding, the resulting backplate undergoes online inspection and finished product inspection. During online inspection, machine vision is used to check the integrity of the double-folded edges, hole accuracy, flatness, and plating condition, and non-conforming products are automatically sorted. During finished product inspection, the dimensions, double-folded edge structure, flatness, torsional resistance, and corrosion resistance are checked. The external tolerance is controlled to ±0.05mm, the hole position accuracy to ±0.03mm, the double-folded edge overlap to be no greater than 0.03mm with no plating peeling, wrinkles, or cracks, the finished product flatness to be no greater than 0.3mm / m, the deformation after the torsional test to be no greater than 0.2mm with no permanent deformation, and the neutral salt spray test to be no less than 96 hours with no red or white rust. Post-processing does not require pickling or electroplating; only the edges are micro-beveling to remove burrs. The micro-beveling radius is R=0.3mm. Subsequently, rust-proof film is used for packaging to reduce the risk of surface scratches and corrosion during transportation and storage.
[0049] The lightweight backplate manufactured using the above structure and process maintains good structural and corrosion resistance even with a material thickness reduced to 0.5mm. Test results show that the resulting double-folded structure increases the compressive strength of the backplate by 15%, impact strength by 18%, and load-bearing capacity by 20% compared to a traditional 0.8mm electro-galvanized single-folded backplate. Under the same torque, the torsional deformation is only 32% of that of a traditional 0.8mm single-folded backplate. After 1000 cycles of thermal cycling (-20℃ to 60℃) and 500 cycles of torque fatigue testing, the backplate shows no permanent torsional deformation, and its flatness still meets assembly requirements. Furthermore, due to the use of galvanized steel as the base material, its salt spray resistance can reach over 96 hours. Therefore, the lightweight backplate with double-folded edge stamping integral molding described in this embodiment can take into account lightweight, corrosion resistance, edge rigidity and torsional resistance, and is suitable for TV backlight module backplates, display device backplates, commercial display device backplates, educational display device backplates and other application scenarios that require strength and stability of large-size thin plate components.
[0050] Example 2
[0051] During online sorting and inspection of the lightweight backplate integrally formed by double-folded stamping as described in Example 1, the inventors discovered that: because the double-folded reinforcing parts of the backplate are continuously arranged along adjacent sides, and a transition connection structure is formed in the corner area by the corner transition part and the tapering avoidance sections on both sides, the corner area simultaneously exhibits composite geometric features such as double-folded edge contour, rounded corner transition contour, and local tapering avoidance contour. Compared with ordinary flat parts or single-folded parts, the structural morphology of the corner area is more complex. During image acquisition and contour recognition, situations easily arise where the appearance of normal transition morphology and abnormal forming morphology are similar, the corner transition boundary is not easy to extract stably, and subtle forming deviations are difficult to distinguish accurately. Especially when there are slight differences in the length of the recessed avoidance section, local undulations in the corner transition contour, or slight asymmetry in the contours on both sides of the angle bisector reference axis, sorting methods based on the overall outer contour, single size threshold, or common defect judgment rules are difficult to accurately determine the consistency of the corner transition forming of this type of backplate, thus affecting the sorting accuracy of qualified parts, rework parts, and rejected parts. Based on this, this embodiment further proposes a sorting system for sorting the double-folded stamped integrated lightweight backplate described in Embodiment 1. By identifying, quantifying, and classifying the transition forming relationship between the corner transition section and the recessed avoidance sections on both sides, it achieves effective sorting of the forming consistency of the corner area of this type of backplate.
[0052] like Figure 4 and 5 ,
[0053] A sorting system for sorting the aforementioned lightweight backplate formed by double-folded stamping, comprising:
[0054] The conveying and positioning unit is used to convey the backplate to be sorted and position the corner area of the backplate to the detection station; the attitude correction unit is used to establish an angle bisector reference axis based on the edge contours of the adjacent two sides of the backplate body and to normalize the attitude of the corner area.
[0055] The image acquisition unit is used to acquire corner images including the double-folded edge reinforcement, the corner transition section, and the two side closing avoidance sections;
[0056] A contour extraction unit is used to extract the corner transition contour and the closing avoidance contour located on both sides of the corner transition portion from the corner image.
[0057] The transition continuity calculation unit is used to calculate the transition continuity index based on the effective length of the two side closing avoidance sections and the curvature undulation degree of the corner transition profile, so as to characterize the degree of continuous forming between the corner transition section and the two side closing avoidance sections.
[0058] The closing coordination degree calculation unit is used to calculate the closing coordination degree index based on the effective length of the closing avoidance sections on both sides and the degree of mirror deviation of the closing avoidance contours on both sides relative to the angle bisector reference axis, so as to characterize the degree of symmetrical coordination between the closing avoidance sections on both sides and the corner transition section.
[0059] The sorting execution unit is used to generate a corner transition forming consistency evaluation quantity based on the transition continuity index and the corner finishing coordination index, and to control the sorting mechanism to sort the back plate into qualified parts, rework parts or rejected parts based on the corner transition forming consistency evaluation quantity.
[0060] In this embodiment, the sorting system is deployed at an online sorting station after stamping and before post-processing of a lightweight backplate formed by double-folded stamping. The system execution architecture includes: a conveying and positioning unit, an attitude correction unit, an image acquisition unit, a contour extraction unit, a transition continuity calculation unit, a closing coordination calculation unit, and a sorting execution unit. The conveying and positioning unit, image acquisition unit, and sorting execution unit are connected to a host computer or industrial control computer via an industrial Ethernet network. The industrial control computer runs a corner recognition and index calculation program, and the sorting execution unit is connected to a PLC to drive the sorting mechanism. This system is used for online judgment of the corner areas of the backplate, focusing on identifying the transition consistency between the corner transition section 21 and the closing avoidance sections 22 on both sides, thereby separating qualified parts, rework parts, and rejected parts.
[0061] In this embodiment, the input data includes three categories. The first category is backplate identity and workstation data, including backplate serial number, workstation number, conveying cycle number, and corner number; the second category is image data, including original image frames of the corner area, image acquisition timestamp, exposure time, lens magnification, pixel size, and light source channel status; the third category is calibration and reference data, including camera intrinsic and extrinsic parameters, pixel physical size conversion coefficient, angle bisector reference axis establishment rules, reference curvature, sorting threshold, and standard sample contour. The image acquisition unit can use an area array industrial camera with a telecentric lens to achieve static corner acquisition, or a line scan camera to achieve dynamic stitching acquisition during continuous backplate conveying. For ease of reproduction, this embodiment preferably uses a global shutter area array industrial camera with a resolution of 5 megapixels or higher with a telecentric lens, a single pixel spatial resolution of 4μm / pixel to 8μm / pixel, a trigger frequency synchronized with the conveying cycle, and acquires 1 to 3 frames of images for each corner of each backplate, with an exposure time of 0.2ms to 2ms. If a multi-angle simultaneous acquisition scheme is adopted, two to four cameras can be used to capture images of different angles in parallel. The image size output by each camera is preferably 2448×2048 or higher. The image data is preferably stored in 8-bit or 12-bit grayscale format.
[0062] In this embodiment, the conveying and positioning unit can be composed of a servo conveyor belt, a blocking and positioning mechanism, and a photoelectric trigger. The photoelectric trigger is used to detect the back panel entering the imaging area; the servo conveyor belt is used to convey the back panel at a constant speed or in a segmented stop manner; the blocking and positioning mechanism is used to keep the target corner within a preset field of view during imaging. Combined with the previous stamping cycle, the conveying speed in this embodiment can be set to 10 to 30 pieces per minute, corresponding to a single corner imaging window time of 20ms to 200ms. To prevent edge jitter of the 0.5mm thin plate during conveying, it is preferable to set a negative pressure adsorption platform or a low-attraction magnetic support platform under the conveyor belt so that the back panel is partially attached to the reference plane during imaging.
[0063] In this embodiment, the attitude correction unit uses the edge contours of adjacent two sides of the backplate body as the attitude reference. Specifically, it extracts two main edge lines near the corner of the image, denoted as the first and second main edges, respectively. Then, it obtains the direction vectors of the two edges through least-squares line fitting. Subsequently, it calculates the angle bisector of the angle between the two direction vectors and establishes the angle bisector reference axis using the corner's geometric vertex and the angle bisector direction. The corner's geometric vertex is preferably determined by the theoretical intersection of the fitted lines of the two main edges; if the actual corner lacks a physical cusp due to rounded corners, the intersection of the extended lines of the two main edges is used as the geometric vertex. Based on this, affine or perspective transformations are used to uniformly rotate the corner region to a preset attitude, ensuring the angle bisector reference axis is in a fixed direction, preferably the vertical direction of the image. After attitude correction, images of different backplates and different corners can be extracted and parameter calculated within a unified coordinate framework.
[0064] In this embodiment, the original image acquired by the image acquisition unit needs to be preprocessed before being transmitted to the contour extraction unit. Preprocessing steps preferably include: grayscale normalization, flat-field correction, local contrast enhancement, noise suppression, and reflection suppression. Since the front panel backplate is made of galvanized steel, zinc layer reflection and local scratches can interfere with edge recognition. Therefore, in this embodiment, coaxial diffused light and low-angle strip side lighting are preferably used for combined illumination. For highlight areas, a saturation pixel suppression strategy can be adopted: when the width of a continuous highlight area is less than 0.08mm, neighborhood grayscale bilinear interpolation is used to complete it; when the width of a continuous highlight area is greater than 0.08mm, a re-encoder is triggered; if a valid contour cannot be recovered after the re-encoder, the corner is marked as having an invalid contour, and the sorting execution unit directly determines it as a rework or rejection part. This degradation strategy ensures that the system can still operate under conditions of coating reflection, local stains, or slight vibration.
[0065] In this embodiment, the contour extraction unit extracts the corner transition contour and the closing avoidance contours located on both sides of the corner transition from the pose-corrected corner image. The preferred contour extraction process is as follows: first, the image is smoothed using Gaussian filtering or bilateral filtering; then, the edge response is obtained using the Canny operator or Sobel operator; finally, the edge point coordinates are obtained using a sub-pixel edge localization method. To ensure stable subsequent curvature calculations, this embodiment preferably uses a three-point parabolic fitting method or a gray-level gradient centroid method to achieve sub-pixel edge localization. After sorting the extracted edge points by arc length, they are assigned to the corner transition contour, the left closing avoidance contour, and the right closing avoidance contour, respectively. The corner transition contour refers to the contour segment connecting the left and right double-folded main body and forming a rounded corner transition; the closing avoidance contour refers to the contour segment located on both sides of the corner transition, contracting from the double-folded main body towards the corner transition to form a avoidance. For discontinuities in the contour less than 0.20 mm, spline interpolation based on the proximity of the arc length can be used to fill the gaps; for discontinuities longer than 0.20 mm or exceeding 5% of the total length of the corresponding contour, the contour extraction is deemed to have failed.
[0066] In this embodiment, the execution steps corresponding to the sorting system are as follows.
[0067] S1, completed by the conveying and positioning unit, which conveys the backplate to be sorted to the inspection station and locks the corner area;
[0068] S2, completed by the attitude correction unit, that is, establishing the angle bisector reference axis and realizing the pose normalization of the corner image;
[0069] S3 is completed by the image acquisition unit and the contour extraction unit, that is, acquiring the corner image and extracting the corner transition contour and the side closing avoidance contour.
[0070] S4. The transition continuity calculation unit completes the calculation, which is to form the transition continuity index X based on the effective length and the degree of curvature fluctuation.
[0071] S5. The closing coordination degree calculation unit completes the calculation, which is to form the closing coordination degree index Y based on the effective length and the degree of mirror deviation.
[0072] S6, completed by the sorting execution unit, involves generating the corner transition forming consistency evaluation quantity Z based on X and Y, and performing sorting according to the threshold. In this way, the system forms a complete closed loop from input, preprocessing, structure identification, index calculation to sorting output.
[0073] This embodiment requires calibration and threshold calibration. The calibration sample preferably includes 200 to 500 qualified backplate samples, 100 to 300 rework samples, and 100 to 300 rejected samples. Sample labels are determined by manual verification combined with results from a 2D image analyzer or coordinate measuring machine. The calibration stage mainly determines four types of data: the conversion factor from pixels to physical dimensions, the reference curvature of the corner transition section, the extraction rules for the effective length of the edge avoidance section, and the sorting threshold. Since previous designs already have process requirements such as online detection accuracy, flatness, and double-fold integrity, the goal of threshold calibration in this embodiment is to ensure that the false negative rate for rework and rejected parts is less than 2%, and the false rejection rate for qualified parts is less than 5%.
[0074] It should be noted that X, Y, and Z are naturally coupled through the convergence term, the exponential decay term, and the final convergence mean. When smoothing filtering is used in the preprocessing stage, the convolution coefficients involved are only used to improve the stability of curvature calculation. For example, when Savitzky-Golay smoothing is preferred, its convolution coefficients are automatically obtained through local polynomial least squares fitting.
[0075] Specifically, the transition continuity calculation unit is used to calculate the transition continuity index X according to the following formula:
[0076]
[0077] Among them, l1 and l2 are the effective lengths of the corner transition sections on both sides of the narrowing clearance section;
[0078] In this embodiment, the transition continuity index X is used to quantify whether the corner transition section 21 and the two side closing avoidance sections 22 are continuous and seamless. Its input parameters include: the effective length of the left closing avoidance section, the effective length of the right closing avoidance section, the discrete sampling point sequence on the corner transition profile, the curvature values of adjacent sampling points, and the reference curvature of the corner transition section. The units of l1 and l2 are preferably millimeters, and κ... i κ i+1 and κ r The unit is the reciprocal of millimeters. X is a dimensionless quantity. The larger the X value, the more continuous and smooth the corner transition; the smaller the X value, the more discontinuous the corner transition or the more drastic the curvature fluctuation.
[0079] In this embodiment, the extraction methods for l1 and l2 should be clearly defined. Preferably, the left and right closing avoidance contours are determined by using the two sides of the angle bisector reference axis as boundaries. The effective length of the closing avoidance segment on each side is defined as follows: starting from the connection point between the closing avoidance contour and the corner transition contour, the arc length along the closing avoidance contour is accumulated until it reaches a position where it tends to be parallel to the main contour of the double-folded edge. The resulting arc length is the effective length of the corresponding side. The position where it tends to be parallel is preferably defined as the angle between the tangent direction of three consecutive sampling points and the direction of the main edge of the corresponding side changes by less than 2°, and the rate of change of the tangent angle between adjacent sampling points is less than 0.5° / point. To avoid edge noise causing the effective length to be too short, it is preferred that the effective length on each side should not be less than 0.3mm; if it is less than this value, it is considered that the closing avoidance segment on that side has not been effectively identified.
[0080] In this embodiment, the curvature fluctuation coefficient C of the corner transition profile c It is obtained through curvature discrete difference construction. The specific steps are as follows: First, the corner transition contour is resampled at equal intervals according to the arc length, and the resampling interval is preferably 0.02mm to 0.10mm, preferably 0.05mm; then, the coordinate sequence after resampling is smoothed, preferably using the Savitzky-Golay method or cubic spline smoothing. If the Savitzky-Golay method is used, the window length is preferably 5 to 11 points, and the polynomial order is preferably 2nd or 3rd order; then, the first and second derivatives are calculated using the smoothed contour coordinates, and the curvature value of each sampling point is calculated according to the plane curve curvature formula.
[0081] C c Let be the normalized curvature fluctuation coefficient of the corner transition profile, and:
[0082]
[0083] Among them, κ i and κ i+1 These represent the curvature values at adjacent sampling points on the corner transition profile, κ. r is the reference curvature of the corner transition section, and N is the number of sampling points on the corner transition profile.
[0084] In this embodiment, if the contour extraction unit finds that the number of sampling points for the corner transition contour is less than 7, or that after smoothing there are still more than three consecutive sampling points whose curvature cannot be calculated, then X is not calculated further, and the corner is directly marked as having invalid transition continuity. The corresponding sorting execution logic then processes it as a rework or rejection piece. This boundary processing rule ensures that the system will not give false high scores when there are obvious image defects or incomplete contours.
[0085] Specifically, the closing coordination degree calculation unit is used to calculate the closing coordination degree index Y according to the following formula:
[0086]
[0087] Wherein, l1 and l2 are the effective lengths of the clearance sections on both sides of the corner transition section; E m The normalized mirror image deviation of the side-to-side recessed avoidance contours relative to the angle bisector reference axis is given, and:
[0088]
[0089] Where, p i and q i These are the corresponding sampling points on the contours of the angle bisector reference axis, M(q) i Let q be a point. i Regarding the mirror image point of the angle bisector reference axis, D is the diagonal reference length of the corner detection area, and N is the number of corresponding sampling points.
[0090] The first term is used to ensure that the lengths of the avoidance sections on both sides are coordinated; the second term uses the mirror deviation to characterize whether the left and right shapes are symmetrical.
[0091] Y is used to quantify whether the corner transition sections on both sides are symmetrical and coordinated. Its input parameters include: the effective lengths l1 and l2 of the left and right corner transition sections, and the corresponding sampling points p on the corner transition contours on both sides. i q i The angle bisects the reference axis and the diagonal reference length D of the corner detection area. Where p i q i These are two-dimensional point coordinates, in millimeters; DDD is in millimeters; E m is a dimensionless quantity; Y is a dimensionless quantity, usually between 0 and 1.
[0092] In this embodiment, the corresponding sampling point pairs are constructed as follows. First, resampling is performed along the left and right side contours of the narrowing avoidance area using the normalized arc length parameter. The normalized arc length parameter refers to defining the starting point of each narrowing avoidance area contour as 0 and the ending point as 1, and then sampling at equal intervals τ. i =i / (N−1) sampling, where N is preferably 20 to 100, then take the i-th sampling point on the left contour as p i On the right contour, sampling points at the same normalized arc length position are taken as q. i This method of constructing point pairs avoids mismatches caused by slight differences in the physical lengths of the left and right contours. If a valid point cannot be obtained at the corresponding normalized position on a certain side contour, neighbor interpolation is used to fill in the gaps; if more than 5 consecutive points are missing, the corner mirror comparison is deemed invalid.
[0093] In this embodiment, the mirror deviation Em Constructed according to the formula. Specifically, first, for the right contour point q i Perform a mirror transformation with respect to the angular bisector reference axis to obtain the mirror point M(q i ). Then calculate the Euclidean distance between the left point p i and this mirror point, and then sum the squared distances of all point pairs, and normalize it with the number of point pairs N and the square of the diagonal reference length D of the detection area to obtain E m . The reason for using D 2 for normalization is that: under different models or different backplane specifications, the angular field of view sizes may be different. If not normalized, the determination significance of the same absolute deviation in a small field of view and a large field of view is not consistent. After normalizing the mirror deviation with the field of view scale, Y can be comparable between different specifications of backplanes.
[0094] Specifically, when both of the two-side closing and avoiding segments are effectively recognized and their effective lengths are greater than zero, the sorting execution unit is used to calculate the angular transition forming consistency evaluation quantity Z according to the following formula:
[0095]
[0096] Compare the angular transition forming consistency evaluation quantity Z with a preset sorting threshold; when Z≥T1, it is determined as a qualified part; when T2≤Z<T1, it is determined as a repaired part; when Z<T2, it is determined as a rejected part, where T1>T2>0.
[0097] The mechanism is that: if both X and Y are large, then Z is large; if either one of X and Y is small, then Z drops significantly; if the difference between the two is large, then Z is closer to the smaller one. This can avoid the situation that a part with good continuity but poor symmetry or good symmetry but poor continuity is still misjudged as qualified.
[0098] In this embodiment, the thresholds T1 and T2 need to be determined through calibration samples. The following calibration process is adopted in this embodiment. First, collect at least 150 qualified parts, repaired parts, and rejected parts from the mass production samples, and each part contains at least one angular part that has been manually reviewed. Subsequently, divide the samples into a threshold fitting set and a verification set according to a ratio of 7:3. For each angular part in the fitting set, first calculate X, Y, and Z, and then, with the manual label as the true value, count the qualified false rejection rate, repaired false judgment rate, and rejected missed detection rate under different threshold combinations. It is preferred to determine the thresholds using the following constraints: First, the rejected part missed detection rate is not higher than 1%; second, the repaired part false release rate is not higher than 3%; third, the qualified part false rejection rate is not higher than 5%. Among all the threshold combinations that meet the above constraints, select the group with the highest comprehensive accuracy as T1 and T2. The thresholds determined in this way are not subjective experience values, but are derived from the statistical results of the calibration samples and meet the engineering implementation requirements
[0099] In this embodiment, the prerequisite that the effective lengths are all greater than zero should also be combined with the abnormal working condition handling rules. If the effective length of the avoidance section on either side of a corner cannot be calculated due to severe reflection, stains, edge damage, or missing contours, or if the calculated value is less than 0.30mm, then Z calculation will not be performed, and the corner will be directly marked as an invalid corner. For the final sorting result of a single back panel, the following rules can be adopted: if there is at least one rejection corner among the four corners, the back panel is determined to be a rejection piece; if there are no rejection corners but there is at least one rework corner, the back panel is determined to be a rework piece; only when all corners are qualified corners is the entire back panel determined to be a qualified piece.
[0100] In this embodiment, the sorting execution unit communicates with the PLC, which controls the cylinder push rod, shift fork mechanism, or robotic arm to send the backplate to different channels. Qualified parts enter the subsequent post-processing or packaging station, rework parts enter the manual re-inspection or partial shaping station, and rejected parts enter the defective product buffer area. Since the previous case already has online detection and sorting stations, this only further refines the original sorting logic for double-fold integrity, flatness, and plating status to the structural consistency level of the corner transition section 21 and the tapering avoidance section 22.
Claims
1. A lightweight backplate integrally formed by double-folded stamping, characterized in that, include: Includes a back plate body (1), at least a portion of the periphery of the back plate body (1) is provided with a double-folded edge reinforcement (2), the double-folded edge reinforcement (2) is integrally formed by at least two stamping and bending of the edge of the back plate body (1), and is configured as a double-folded edge structure with a back fold and edge wrapping extending along the periphery of the back plate body (1), so as to improve the structural strength and torsional resistance of the edge part of the back plate body (1).
2. The lightweight backplate integrally formed by double-folded stamping according to claim 1, characterized in that, The double-folded edge reinforcement (2) is continuously provided along at least two adjacent sides of the back plate body (1).
3. A lightweight backplate integrally formed by double-folded stamping according to claim 2, characterized in that, The double-folded edge reinforcement (2) on the adjacent two sides is connected by a corner transition part (21) at the corresponding corner. The corner transition part (21) is located between the two adjacent sides and forms a rounded corner transition structure.
4. A lightweight backplate integrally formed by double-folded stamping according to claim 3, characterized in that, The double-folded edge reinforcements (2) located on both sides of the corner transition section (21) are respectively provided with closing clearance sections (22). The closing clearance sections (22) cooperate with the corner transition section (21) so that the double-folded edge reinforcements (2) on the adjacent two sides form a transition connection structure with intervals in the corner area.
5. A lightweight backplate integrally formed by double-folded stamping according to claim 4, characterized in that, The end of the double-folded edge reinforcement (2) is provided with an end closing part (23), which is formed by folding back the end of the double-folded edge reinforcement (2).
6. A lightweight backplate integrally formed by double-folded stamping according to claim 5, characterized in that, The back plate body (1) and the double-folded edge reinforcement (2) are integrally stamped from the same metal sheet without welding. The metal sheet is a galvanized steel sheet with a thickness of 0.5mm.
7. A sorting system, characterized in that, For sorting lightweight backplates formed by double-folding stamping as described in any one of claims 1-6, comprising: The conveying and positioning unit is used to convey the backplate to be sorted and position the corner area of the backplate to the detection station; the attitude correction unit is used to establish an angle bisector reference axis based on the edge contours of the adjacent two sides of the backplate body and to normalize the attitude of the corner area. The image acquisition unit is used to acquire corner images including the double-folded edge reinforcement, the corner transition section, and the two side closing avoidance sections; A contour extraction unit is used to extract the corner transition contour and the closing avoidance contour located on both sides of the corner transition portion from the corner image. The transition continuity calculation unit is used to calculate the transition continuity index based on the effective length of the two side closing avoidance sections and the curvature undulation degree of the corner transition profile, so as to characterize the degree of continuous forming between the corner transition section and the two side closing avoidance sections. The closing coordination degree calculation unit is used to calculate the closing coordination degree index based on the effective length of the closing avoidance sections on both sides and the degree of mirror deviation of the closing avoidance contours on both sides relative to the angle bisector reference axis, so as to characterize the degree of symmetrical coordination between the closing avoidance sections on both sides and the corner transition section. The sorting execution unit is used to generate a corner transition forming consistency evaluation quantity based on the transition continuity index and the corner finishing coordination index, and to control the sorting mechanism to sort the back plate into qualified parts, rework parts or rejected parts based on the corner transition forming consistency evaluation quantity.
8. A sorting system according to claim 7, characterized in that: The transition continuity calculation unit is used to determine the transition continuity index based on the effective length coordination of the avoidance sections on both sides of the corner transition section and the curvature undulation of the corner transition profile. Among them, the effective length coordination degree of the two-sided closing avoidance section is used to reflect the matching state of the two-sided closing avoidance section in length, and the curvature fluctuation degree of the corner transition profile is used to reflect the smoothness of the curvature change of the corner transition profile along the extension direction. The curvature fluctuation is obtained by statistically analyzing the curvature changes at adjacent sampling points on the corner transition profile, and then normalized by combining the reference curvature of the corner transition. The closer the effective lengths of the two side closing clearance sections are and the smaller the curvature fluctuation of the corner transition profile, the greater the transition continuity index.
9. A sorting system according to claim 8, characterized in that: The corner transition coordination calculation unit is used to determine the corner transition coordination index based on the effective length coordination of the corner transition avoidance sections on both sides and the mirror deviation of the corner transition avoidance contours on both sides relative to the angle bisector reference axis. The degree of mirror deviation of the two sides of the narrowing avoidance contour relative to the angle bisector reference axis is obtained by comparing the mirror position of the sampling point of the narrowing avoidance contour on one side of the angle bisector reference axis with the corresponding sampling point of the narrowing avoidance contour on the other side, and then normalizing it in combination with the diagonal reference length of the corner detection area. The closer the effective lengths of the two closing clearance sections are and the smaller the mirror deviation of the two closing clearance contours, the greater the closing coordination index.
10. A sorting system according to claim 9, characterized in that: The sorting execution unit is used to generate the corner transition forming consistency evaluation quantity based on the coordination degree of the transition continuity index and the closing coordination index when both sides of the closing avoidance section are effectively identified and their effective lengths are both greater than zero. The corner transition molding consistency evaluation quantity is used to comprehensively reflect the continuous molding level between the corner transition section and the two side closing avoidance sections, as well as the symmetrical coordination level between the two side closing avoidance sections. When both the transition continuity index and the closing coordination index are large and the difference between them is small, the corner transition forming consistency evaluation value increases; when either the transition continuity index or the closing coordination index is small or the difference between them increases, the corner transition forming consistency evaluation value decreases. The sorting execution unit is further configured to compare the corner transition forming consistency evaluation quantity with a preset sorting threshold. When the corner transition forming consistency evaluation quantity is not lower than the first threshold, it is determined to be a qualified part; when the corner transition forming consistency evaluation quantity is lower than the first threshold but not lower than the second threshold, it is determined to be a rework part; when the corner transition forming consistency evaluation quantity is lower than the second threshold, it is determined to be a rejected part, wherein the first threshold is greater than the second threshold.