Stamping and bending process for inner container of vehicle-mounted refrigerator

Abstract

The invention discloses a stamping and bending process for an inner container of a vehicle-mounted refrigerator. According to the stamping and bending process, an integrally-formed main body structure is included; the main body structure comprises a main plate and a flanging side frame arranged on the edge of the top of the main plate, a plurality of arc-shaped positioning grooves are formed in the top of the side frame, and the arc-shaped positioning grooves are located in a bent connecting area of the flanging side frame and the main plate. A flanging welding plate is arranged on the edge of one side of the main plate, a plurality of mounting lugs are arranged at the bottom of the main plate, a first positioning block is arranged at the bottom of the flanging welding plate and arranged on the edge area of the bottom of the flanging welding plate, and a second positioning block is arranged on the side, opposite to the first positioning block, of the main plate. The arc-shaped positioning groove is formed in the bending connection area of the flanging side frame and the main plate and serves as a stress concentration point and a deformation guide point, the deformation track of a material in the bending process is effectively guided, stress is prevented from being excessively concentrated in a local area, the thin-wall plate can be subjected to uniform plastic deformation in the complex bending process, and the bending quality of the thin-wall plate is improved. The occurrence probability of wrinkling, cracking and the like is obviously reduced.

Description

Technical Field

[0001] This invention relates to the field of mechanical manufacturing technology, and in particular to a stamping and bending process for the inner liner of a vehicle refrigerator. Background Technology

[0002] As an important comfort feature in modern mobile lifestyles, car refrigerators are experiencing continuous market demand growth, placing higher demands on product portability, energy efficiency, reliability, and aesthetics. The inner liner, as a key component of car refrigerators, directly affects the overall quality and user experience. Currently, the manufacturing of car refrigerator inner liners mainly relies on aluminum profile extrusion and stamping / stretching processes.

[0003] Aluminum profile extrusion is suitable for producing structural parts with thick walls, but it struggles to achieve complex geometries. Surface defects such as lines and scratches are common, especially at corners and curved areas, resulting in poor dimensional accuracy and requiring extensive post-processing corrections. Furthermore, the process is inefficient, hindering large-scale continuous production. High-cost and easily worn molds contribute to overall high costs. Additionally, its reliance on thick-walled materials limits lightweight product design.

[0004] While stamping and stretching processes can produce thinner-walled inner liners and theoretically offer higher material utilization, they are prone to defects such as wrinkling and cracking in areas of curvature variation when manufacturing deep, geometrically complex inner liners. Even if a liner is successfully formed, it is often accompanied by surface damage and dimensional deviations, affecting sealing performance and assembly accuracy. This process requires high-precision molds and complex parameter control, resulting in high mold costs, a complex process flow, low production efficiency, and limited applicability to irregular or complex structures.

[0005] Therefore, it is necessary to provide a stamping and bending process for the inner liner of a vehicle refrigerator to solve the above-mentioned technical problems. Summary of the Invention

[0006] This invention overcomes the shortcomings of the prior art and provides a stamping and bending process for the inner liner of a vehicle refrigerator.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a stamping and bending process for the inner liner of a vehicle refrigerator, comprising: an integrally formed main structure;

[0008] The main structure includes: a motherboard, a flanged side frame set at the top edge of the motherboard, and several arc-shaped positioning grooves on the top of the side frame, which are located in the bending connection area between the flanged side frame and the motherboard.

[0009] One side edge of the main plate is provided with a flange welding plate, the bottom of the main plate is provided with a plurality of mounting ears, the bottom of the flange welding plate is provided with a first positioning block, the first positioning block is arranged at the bottom edge area of the flange welding plate, the side of the main plate opposite to the first positioning block is provided with a second positioning block, the geometric shape of the second positioning block matches the first positioning block, and the first positioning block and the second positioning block coincide when the flange welding plate is overlapped with the main plate by bending.

[0010] The side edge of the flange welding plate is tightly attached to the outer surface of the main plate to form an overlapping joint after the first positioning block and the second positioning block coincide, and the overlapping joint constitutes a welding area.

[0011] In a preferred embodiment of the present application, the thickness of the main plate ranges from 0.6 to 1.2 mm, the material of the main plate is an aluminum alloy plate, and the surface of the main plate is pre-passivated.

[0012] In a preferred embodiment of the present application, the flange side frame extends upwards along the circumferential edge of the main plate and is formed by a bending process, the height of the flange side frame corresponds to the depth of the inner liner of the vehicle-mounted refrigerator, and a fillet transition structure with a specific inner bending radius is formed at the connection between the flange side frame and the main plate, and the inner bending radius of the fillet transition structure ranges from 1.5 to 3.0 mm.

[0013] In a preferred embodiment of the present application, the geometric shape of the arc-shaped positioning groove is a semicircular or elliptical cross section, the depth of the arc-shaped positioning groove is 0.3 to 0.6 times the thickness of the main plate, and the arc of the arc-shaped positioning groove matches the preset bending angle, which is used to guide the deformation trajectory of the material in the bending process and achieve stress release.

[0014] In a preferred embodiment of the present application, the thickness of the flange welding plate is the same as that of the flange side frame, and the material, thickness and surface treatment process of the flange welding plate are the same as those of the main plate.

[0015] In a preferred embodiment of the present application, the shape of the first positioning block is a trapezoidal protruding structure, the shape of the second positioning block is a trapezoidal protruding structure matching the first positioning block, the depth and width of the second positioning block correspond to those of the first positioning block, the first positioning block is located above the second positioning block, and the length of the welding area is the same as the effective overlapping length of the flange welding plate.

[0016] A stamping and bending process for a vehicle-mounted refrigerator inner liner, comprising the following steps:

[0017] S10: Obtain a metal plate with a predetermined size, and perform stamping processing to form a flat plate preform with a main plate, a flange side frame, an arc-shaped positioning groove, a flange welding plate, a mounting ear, a first positioning block and a second positioning block at one time;

[0018] S20: Perform first pass bending on the flat plate preform to form a preliminary upright edge of the flange side frame and the flange welding plate;

[0019] S30: performing a second pass of bending on the semi-finished product after the first pass of bending, so that the flange welding plate overlaps the corresponding edge of the main plate and the first positioning block overlaps the second positioning block;

[0020] S40: welding the welding area to form a firm inner container structure;

[0021] S50: finishing the welded inner container to correct the existing geometric deformation;

[0022] S60: removing the auxiliary support or positioning structure temporarily formed during the bending or welding process;

[0023] S70: surface treatment of the welding area to remove welding spatter and oxides, and to smooth other surfaces.

[0024] In a preferred embodiment of the present application, in S10, the stamping process is completed using high-precision numerical control stamping equipment and progressive dies or compound dies to ensure that all features on the flat plate preform are formed at one time. The die material is selected from high-strength wear-resistant steel and is heat treated to achieve a high hardness of HRC 60-62.

[0025] In a preferred embodiment of the present application, in S30, the second pass of bending is performed by a multi-axis numerical control bending machine. The arc-shaped positioning groove serves as a stress concentration point and a deformation guide point to ensure uniform bending of the material along the preset trajectory. The bending angle is controlled in real time in a closed loop (with a precision of ±0.1°), and the downward stroke of the upper die is controlled to ensure that the first positioning block overlaps the second positioning block without gaps, with a gap control of less than 0.05 mm.

[0026] In a preferred embodiment of the present application, in S40, the welding process is performed using an automatic laser welding system.

[0027] The present application solves the defects in the background art and has the following beneficial effects:

[0028] (1) The present application provides a stamping and bending process for the inner container of a vehicle-mounted refrigerator. By providing an arc-shaped positioning groove in the bending connection area between the flange side frame and the main plate, the groove serves as a stress concentration point and a deformation guide point to effectively guide the deformation trajectory of the material during bending, avoid excessive stress concentration in local areas, and enable uniform plastic deformation of the thin-walled plate during complex bending, thereby significantly reducing the probability of common defects such as wrinkling and cracking. Compared with the surface texture and scratch defects that often occur in traditional extrusion processes, and the wrinkling and cracking problems caused by uneven material deformation in stamping and drawing processes, the present application solves the stress concentration problem of the material during bending. This not only improves the surface quality and geometric precision of the inner container, but also provides an ideal foundation for subsequent welding and surface treatment, making the overall appearance of the inner container more aesthetically pleasing and the structure more reliable.

[0029] (2) The present application provides a stamping and bending process for the inner container of a vehicle-mounted refrigerator. The gapless coincidence of the edge of the flange-welded plate and the main plate is realized through the trapezoidal protruding structure of the first positioning block and the second positioning block, ensuring the close fit of the lap joint. The self-alignment of the flange-welded plate and the main plate in the bending process avoids the lap joint gap and misalignment caused by inaccurate positioning in the traditional process. Compared with the gap, incomplete fusion or porosity defects often occurring in the welding area in the traditional process, the integrity of the welding area is ensured, and the welding joint is more firm. The positioning cooperation not only improves the sealing performance of the inner container, but also greatly reduces the leakage risk, making the inner container more reliable in use, while reducing the subsequent repair work and improving the overall production efficiency.

[0030] (3) The present application provides a stamping and bending process for the inner container of a vehicle-mounted refrigerator. By adopting the stamping and bending process, all features required for the inner container are formed at one time by numerical control stamping equipment, and combined with multi-axis numerical control bending and automatic laser welding technology, the efficient and high-precision manufacturing of the inner container is realized, avoiding the high dependence on the mold and low production efficiency of the traditional extrusion process, and overcoming the forming defects caused by the plastic deformation limit of the material in the stamping and drawing process. Compared with the existing process, the stamping and bending process of the present application significantly improves the production efficiency and material utilization rate while ensuring the product quality, and reduces the generation of waste materials. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, a brief introduction to the drawings needed to be used in the embodiments or prior art description will be given below. Obviously, the drawings described below are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor;

[0032] Figure 1 is a step S10 product three-dimensional structure schematic diagram of the preferred embodiment of the present application;

[0033] Figure 2 is a product finished appearance three-dimensional structure schematic diagram of the preferred embodiment of the present application;

[0034] Figure 3 is an A part enlarged three-dimensional structure schematic diagram of the preferred embodiment of the present application;

[0035] Figure 4 is a step S20 secondary bending product change top view schematic diagram of the preferred embodiment of the present application;

[0036] Figure 5 is a step S20 secondary bending product change front view schematic diagram of the preferred embodiment of the present application.

[0037] In the figure: 1, main plate; 2, flanging side frame; 3, arc-shaped positioning groove; 4, flanging welding plate; 5, mounting lug; 6, first positioning block; 7, second positioning block; 8, welding area. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0039] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in a variety of ways beyond the specific details set forth herein, and the scope of the present application is not limited to the specific embodiments described below.

[0040] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the scope of protection of the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0041] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0042] As Figures 1-3 shown, the present application provides a stamping and bending process for a car refrigerator liner, comprising: an integrally formed main body structure;

[0043] The main structure includes: a motherboard 1, a flanged side frame 2 set on the top edge of the motherboard 1, and a number of arc-shaped positioning grooves 3 opened on the top of the side frame, the number of arc-shaped positioning grooves 3 being located in the bending connection area between the flanged side frame 2 and the motherboard 1.

[0044] A flanged welding plate 4 is provided on one side edge of the motherboard 1, and a number of mounting ears 5 are provided on the bottom of the motherboard 1. A first positioning block 6 is provided on the bottom edge area of ​​the flanged welding plate 4. A second positioning block 7 is provided on the side of the motherboard 1 opposite to the first positioning block 6. The geometry of the second positioning block 7 matches that of the first positioning block 6. When the flanged welding plate 4 overlaps with the motherboard 1 by bending, the first positioning block 6 and the second positioning block coincide.

[0045] After the first positioning block 6 and the second positioning block 7 overlap, the lap joint formed by the tight fit between one side of the flanged welding plate 4 and the outer surface of the main board 1 constitutes the welding area 8.

[0046] In this embodiment, the main board 1 serves as the foundation for the inner liner of the vehicle refrigerator, providing a stable bottom support surface. Its dimensions are typically customized based on the overall design volume and installation space of the vehicle refrigerator.

[0047] Furthermore, the mounting ear 5 is integrally stamped from the same material as the main board 1. Its geometry and hole size are designed according to the fixing requirements of the vehicle refrigerator shell. For example, it can be designed as a rectangular lug with a mounting hole of 4.5 mm in diameter. The connection between it and the main board 1 is made of a rounded corner of R3 mm to disperse stress.

[0048] The main function of mounting ear 5 is to provide a stable fixing point for the inner liner inside the car refrigerator shell, ensuring the shock resistance stability of the inner liner during vehicle operation and preventing displacement or damage caused by vibration and impact.

[0049] In a preferred embodiment of the present invention, the thickness of the motherboard 1 is in the range of 0.6-1.2 mm, the material of the motherboard 1 is aluminum alloy sheet, and the surface of the motherboard 1 is pre-passivated.

[0050] Specifically, the thickness range of the main board 1 ensures that the inner liner has sufficient structural rigidity and load-bearing capacity. The material of the main board 1 is aerospace-grade AL5052 aluminum alloy sheet. Aerospace-grade AL5052 aluminum alloy sheet is widely favored for its excellent formability, excellent corrosion resistance and excellent weldability. Its typical yield strength is 195MPa, tensile strength is 255MPa, and elongation is 12-18%, which is the key to enabling it to withstand complex stamping and bending without producing significant defects.

[0051] The surface pre-passivation treatment adopts a chemical conversion film treatment process to uniformly form a dense amorphous oxide film layer with a thickness between 0.5-1.5μm on the surface of AL5052 aluminum alloy substrate;

[0052] For example, by immersing the aluminum alloy liner in a solution containing hexafluorozirconate or trivalent chromium compounds and reacting it at a specific temperature (such as 40-60°C) for several minutes, the film not only greatly improves the corrosion resistance of the aluminum alloy liner, enabling it to effectively resist the erosion of humid environments and acidic or alkaline substances in food, but also provides an ideal adhesion substrate for subsequent surface treatment processes (such as spraying, electrophoresis, or structural bonding), ensuring the aesthetics and durability of the final product.

[0053] In one specific embodiment, the flanged side frame 2 extends upward along the circumferential edge of the main board 1 and is formed by a bending process. The height of the flanged side frame 2 corresponds to the depth of the inner liner of the vehicle refrigerator. The connection between the flanged side frame 2 and the main board 1 forms a rounded corner transition structure with a specific inner bending radius, the inner bending radius of which ranges from 1.5 to 3.0 mm.

[0054] Specifically, the flanged side frame 2 extends upward along the top edge of the main board 1 and is integrally formed from the original sheet metal of the main board 1 through a CNC bending process. The height of the flanged side frame 2 matches the effective internal depth of the inner liner of the vehicle refrigerator;

[0055] For example, for a 20-liter car refrigerator liner, the side frame height can be set to 300 mm to fully ensure the usable volume and functionality of the liner.

[0056] The inner bending radius of the rounded corner transition structure is set between 1.5 and 3.0 mm, for example, 2.0 mm. This choice is based on a comprehensive consideration of the material's plastic deformation characteristics and the structural stress distribution. If the inner bending radius is too small, the material will bear excessive tensile stress in the bending area, which can easily lead to the generation of micro-cracks inside the sheet metal or even macro-cracks, and may also cause severe material springback. Conversely, if the inner bending radius is too large, although stress concentration can be reduced, the geometric squareness and space utilization of the inner liner will be sacrificed, affecting aesthetics and assembly accuracy.

[0057] Therefore, a radius range of 1.5-3.0 mm can ensure the structural strength, stress distribution uniformity, and visually smooth transition of the bending area to the maximum extent, while maintaining excellent molding quality.

[0058] In one specific embodiment, the geometry of the arc-shaped positioning groove 3 is a semi-circular or elliptical cross-section.

[0059] Specifically, the arc-shaped positioning groove 3 is not simply a slot. It is located on the preset bending line of the bending connection area between the flange side frame 2 and the main board 1, that is, at the corner where the material is about to undergo plastic deformation. The geometry of the arc-shaped positioning groove 3 is designed as a semi-circular or elliptical cross section.

[0060] For example, in a specific implementation, it is a semi-circular cross section with a radius of 0.5 mm, which is periodically distributed along the bending line with a spacing of, for example, 10 mm. This cross section shape helps to achieve uniform stress release and transmission during the bending process of the material, and avoids excessive stress concentration in local areas.

[0061] In one specific embodiment, the depth of the arc-shaped positioning groove 3 is strictly controlled, typically 0.3-0.6 times the thickness of the motherboard 1. For example, for a motherboard 1 that is 0.8 mm thick, its depth can be set to 0.4 mm.

[0062] The depth range of 0.3-0.6 times ensures that the arc-shaped positioning groove 3 can effectively serve as a preset trajectory guide point for material deformation and a local stress concentration point, thereby guiding the material to undergo uniform plastic deformation along a specific path, while avoiding excessive weakening of the integrity of the plate structure.

[0063] In one specific embodiment, the arc of the arc-shaped positioning groove 3 is matched with the preset bending angle to guide the deformation trajectory of the material during the bending process and to achieve stress release.

[0064] For example, for a 90° bend, the arc length can be designed to match the unfolded bending length. This design allows the arc-shaped positioning groove 3 to effectively guide the material to bend uniformly along a specific path during the bending process, significantly reducing the probability of common defects such as wrinkling, cracking, or material buildup that may occur in the bending area. Furthermore, it provides a localized stress relief channel.

[0065] Furthermore, it improves the forming quality and reliability of thin-walled sheets during complex bending processes.

[0066] In one specific embodiment, the thickness of the edge welding plate is the same as that of the flanged side frame 2, and the material, thickness and surface treatment process of the flanged welding plate 4 are the same as those of the main board 1, so as to ensure the material compatibility, welding performance and overall appearance uniformity of the final product in the subsequent welding process.

[0067] For example, it also uses AL5052 aluminum alloy sheet, with the same thickness as main board 1, and undergoes the same chemical conversion film pre-passivation treatment before processing;

[0068] In one specific embodiment, the first positioning block 6 is a trapezoidal protrusion structure, the second positioning block 7 is a trapezoidal protrusion structure that matches the first positioning block 6, the depth and width of the second positioning block 7 correspond to the first positioning block 6, the first positioning block 6 is located above the second positioning block 7, and the length of the welding area 8 is the same as the effective overlap length of the flanged welding plate 4.

[0069] Specifically, the first positioning block 6 and the second positioning block 7 overlap, which enables self-alignment and gapless overlap during the overlapping process, effectively preventing relative displacement or misalignment during subsequent automated welding. After overlap;

[0070] One side of the flanged welding plate 4 is tightly fitted to the outer surface of the main plate 1, forming an lap joint that constitutes the welding area 8 for subsequent connection. The length of the welding area 8 is the same as the effective lap length of the flanged welding plate 4, providing sufficient welding area to form a strong and sealed structural connection.

[0071] like Figures 1-5 A stamping and bending process for the inner liner of a car refrigerator includes the following steps:

[0072] S10: Obtain a metal sheet of a preset size, stamp it, and form a flat prefabricated part with a main board 1, a flanged side frame 2, an arc-shaped positioning groove 3, a flanged welding plate 4, a mounting ear 5, a first positioning block 6, and a second positioning block 7 in one step.

[0073] S20: Perform the first bending of the flat precast component to form the initial upright edge of the flanged side frame 2 and the flanged welding plate 4;

[0074] S30: Perform a second bend on the semi-finished product that has undergone the first bend, so that the flanged welding plate 4 overlaps with the corresponding edge of the main plate 1 and the first positioning block 6 and the second positioning block 7 coincide.

[0075] S40: Weld the welding area 8 to form a solid inner liner structure;

[0076] S50: Perform fine finishing on the welded inner liner to correct any existing geometric deformation;

[0077] S60: Remove any temporary auxiliary supports or positioning structures formed during bending or welding.

[0078] S70: Perform surface treatment on welding area 8 to remove welding spatter and oxides, and smooth other surfaces.

[0079] The following will describe each step in detail.

[0080] In S10, a sheet of AL5052 metal of a preset size is obtained, for example, a sheet with a size of 600×400 mm and a thickness of 0.8 mm. The sheet is then stamped. The stamping process is completed by CNC stamping equipment and a customized progressive die or compound die. All the features required for the inner liner are formed on the metal sheet in one go, including the outline of the main board 1, the unfolded shape of the flanged side frame 2, the arc-shaped positioning groove 3, the outline of the flanged welding plate 4, the mounting ear 5, and the first positioning block 6 and the second positioning block 7.

[0081] Specifically, the press equipment is equipped with a servo motor drive system, which can control the press stroke (e.g., control accuracy ±0.01 mm), press speed (e.g., adjustable to 1000 c / min), and press force, ensuring uniform material deformation and dimensional consistency during the press process;

[0082] For example, the critical dimension tolerance is controlled within ±0.05mm. The progressive die or compound die can complete the processing of all features such as cutting, forming, punching and pressing positioning blocks on the metal sheet in one go through a single feed or a single stamping action. For example, the outer contour shearing, positioning hole stamping, arc groove pressing and positioning block protrusion and groove forming can be completed in a single stroke.

[0083] The mold material is made of high-performance, high-strength, wear-resistant steel, such as DC53 or SKD11, and undergoes a strict heat treatment process, such as vacuum quenching and multiple tempering, so that its surface hardness reaches the range of Rockwell hardness (HRC) 60-62, which significantly improves the service life of the mold and ensures the precision and stability of stamped products, effectively reducing burrs and dimensional deviations.

[0084] S20: Perform the first bending of the flat preform to initially form the upright edge of the flanged side frame 2 and the initial upright edge of the flanged welding plate 4, preparing for subsequent positioning and final bending. For example, use a three-axis CNC bending machine to initially bend the two sides of the flat preform by 90° to form an open box structure.

[0085] S30: Perform a second bending on the semi-finished product after the first bending. This bending is a key step in the entire process. Its goal is to make the corresponding edges of the flanged welding plate 4 overlap with the main plate 1, and to make the first positioning block 6 and the second positioning block 7 overlap without gaps.

[0086] Specifically, this is achieved using a multi-axis CNC bending machine, such as a 6-axis CNC hydraulic synchronous bending machine, equipped with an advanced real-time angle measurement system based on laser scanning or visual recognition feedback. This system can perform real-time closed-loop control of the bending angle, achieving a control accuracy of ±0.1°. When bending to form an overlapping structure, the system can monitor the overlapping angle in real time and make fine adjustments based on preset values ​​to ensure that the final overlapping angle error is less than 0.1°.

[0087] This high-precision angle control ensures the final geometric squareness and shape consistency of the inner liner. The arc-shaped positioning groove 3 serves as a preset stress concentration point and deformation guide point, which can ensure that the material undergoes uniform plastic deformation along the set bending trajectory, effectively preventing uneven stress in the bending area, springback (controlling the springback angle within 0.5°), and defects caused by excessive stretching or compression of the material, such as wrinkles or tears.

[0088] Furthermore, by controlling the downward stroke of the upper die and the V-shaped opening of the lower die, the bending machine enables the first positioning block 6 and the second positioning block 7 to overlap without gap, and the overlap gap is strictly controlled within 0.05 mm.

[0089] S40: Automated welding is performed on welding area 8 to form a robust and sealed inner liner structure. The welding process is performed using an automated laser welding system, such as an automated workstation equipped with a 3kW fiber laser, a six-axis robot, and a high-definition vision tracking system. This vision tracking system can scan and correct the welding path in real time before welding. For example, through image recognition technology, it identifies the weld centerline after the positioning blocks are aligned and performs a ±0.05mm calibration to ensure that the laser beam is focused on welding area 8.

[0090] Specifically, laser welding is significantly superior to traditional arc welding or resistance welding due to its high energy density (power density can reach 10^6 W / cm^2), extremely small heat input (more than 50% less than TIG welding), narrow weld (weld width less than 1 mm) and extremely low deformation (workpiece flatness deformation less than 0.1 mm after welding).

[0091] It melts and connects the flanged welding plate 4 to the side of the main plate 1 to form a metallurgical bond, creating an inner liner structure with high strength, good sealing performance, and a smooth appearance. This automated system ensures a high degree of consistency and repeatability in welding quality, significantly improving production efficiency and reducing the uncertainty caused by manual operation;

[0092] The laser welding parameters used, including a laser power of 2.5kW, a welding speed of 3m / min, a defocusing amount of -0.2mm (i.e., the focal point is inside the workpiece), and the protective gas flow rate (high-purity argon, 15 liters / minute), were all calibrated to optimize welding quality and minimize the heat-affected zone (HAZ). The HAZ width was controlled within 0.5mm to maintain the inherent properties of the inner liner material and prevent it from becoming brittle or soft.

[0093] S50: The welded inner liner undergoes fine finishing. This process is completed using customized forming dies or specialized correction fixtures in conjunction with hydraulic or mechanical presses. The aim is to eliminate minor stress deformations and geometric deviations that may accumulate during stamping, bending, and welding, such as localized warpage (correcting warpage from 0.5 mm to 0.1 mm) or angular distortion. Through controlled pressure and shaping, the dimensional and shape accuracy of the inner liner is corrected to within design tolerances, for example, controlling the overall dimensional tolerance within ±0.2 mm, ensuring good compatibility with subsequent assembled components (insulation layer, refrigeration components).

[0094] S60: Remove the auxiliary support structure or positioning fixture temporarily formed during bending or welding. The auxiliary structure is designed so that it can be quickly and non-destructively disassembled after a specific process is completed without affecting the final structure and surface integrity of the inner liner. It is removed without leaving any marks or causing surface scratches by using a vacuum suction cup or mechanical snap-on fixture with a quick-release mechanism.

[0095] S70: Perform fine surface treatment on the welding area 8 to remove welding spatter and oxides, and smooth the other surfaces of the inner liner; the surface treatment of the welding area 8 usually includes mechanical grinding using fine abrasive belts or grinding wheels, using a 400-mesh abrasive belt to remove welding spatter with a diameter of less than 0.5 mm, oxide layer with a thickness of less than 0.1 mm, and local irregular weld protrusions, so that the weld surface is flush with the surrounding material;

[0096] Chemical cleaning is then performed, involving immersion in a mild acidic or mild alkaline cleaning agent to thoroughly remove surface residue and restore the metallic luster. The remaining surfaces of the inner liner are then smoothed to ensure their smoothness and aesthetic appeal.

[0097] Depending on the final application requirements of the inner liner, further surface finishing treatments such as anodizing, spraying, or electrophoresis can be performed. For example, a transparent anodizing treatment with a thickness of 5μm can be carried out to improve the corrosion resistance, wear resistance, and overall aesthetic quality of the inner liner, ensuring that it meets food contact grade material standards or specific appearance requirements.

[0098] Example 1

[0099] A batch of car refrigerator liners were manufactured according to the "stamping and bending process of a car refrigerator liner" of the present invention. The AL5052 aluminum alloy sheet used has a thickness of 0.8 mm and is pre-passivated to form a 1.0 μm thick conversion film. The main board 1 has a size of 450 x 250 mm. The flanged side frame 2 has a height of 280 mm and the radius of the rounded transition at the connection with the main board 1 is set to 2.0 mm. The arc-shaped positioning groove 3 has a semi-circular cross section with a depth of 0.4 mm and is periodically distributed along the bending line with a spacing of 10 mm. The first positioning block 6 is a trapezoidal protrusion with a bottom width of 3.0 mm, a top width of 2.0 mm, and a height of 1.0 mm. The second positioning block 7 is a matching trapezoidal groove.

[0100] In step S10, the stamping stage, an SKD11 die with an HRC61 hardness is used at a stamping speed of 800 c / min, and the tolerance of key feature dimensions is controlled within ±0.04 mm. In step S30, the second bending stage, a multi-axis CNC bending machine equipped with a laser angle measurement system is used, achieving a bending angle accuracy of ±0.08°. The final average overlap gap between the positioning blocks is 0.03 mm, with a maximum of 0.04 mm. In step S40, the laser welding stage, a 3kW fiber laser is used with a power setting of 2.6kW, a welding speed of 3.2 m / min, a defocusing amount of -0.25 mm, argon protection, and an average weld heat-affected zone width of 0.45 mm.

[0101] One hundred samples of the manufactured inner liner were randomly sampled and tested. The results are as follows:

[0102] Dimensional accuracy: The average deviation of the overall dimensions (length, width, height) of the inner liner from the design tolerance (±0.2 mm) is 0.11 mm.

[0103] Weld quality: The weld surface is smooth and free from defects such as porosity, cracks, and undercut. The weld strength is tested by tensile shear, and the average shear strength reaches 150MPa, far exceeding the industry standard requirement of 100MPa. The weld leakage rate (water pressure test at 0.5MPa for 5 minutes) is 0%.

[0104] Surface quality: The conversion film is uniform and intact. After subsequent anodizing treatment, the surface hardness (HV) reaches an average of 80. No red rust or obvious corrosion signs were observed in the salt spray corrosion test (500 hours of neutral salt spray).

[0105] Geometric deformation: After S50 finishing, the average flatness deviation of the main plane of the inner liner is 0.08 mm, and the average verticality deviation of the sidewall is 0.07°.

[0106] Production efficiency: The average production cycle per piece from raw material sheet to finished inner liner (excluding surface finishing) is 85 seconds.

[0107] Material utilization rate: Due to the optimization of stamping and bending processes, the material scrap rate is controlled within 12%.

[0108] Comparative Example 1

[0109] In contrast, the same size and material of the inner liner of a car refrigerator are produced using a traditional stamping and stretching process. This process uses 0.8 mm thick AL5052 sheet metal and is formed in one go through a deep stretching die. During the stretching process, in order to avoid cracking, the stretching depth, stretching speed, lubrication conditions, etc. must be strictly controlled. However, due to the large depth of the inner liner (280 mm) and the presence of right-angle transition areas, the stretching process is prone to excessive thinning, wrinkling, or cracking of the material at the corners.

[0110] One hundred inner liner samples manufactured using traditional stamping and stretching processes were sampled and tested. The results are as follows:

[0111] Dimensional accuracy: Due to material springback and uneven local deformation, the overall dimensional deviation of the inner liner is 0.35 mm on average, and the dimensional deviation in some corner areas reaches 0.5 mm.

[0112] Surface quality: Stretch marks, wrinkles, and orange peel texture with localized stress concentrations were commonly observed at deep stretching points and corners. Furthermore, microcracks appeared in approximately 15% of the samples at corners, resulting in a high scrap rate.

[0113] Wall thickness uniformity: The wall thickness at the bottom of the inner liner is maintained at 0.8 mm, but the wall thickness is significantly reduced on the side walls, especially at the corners, with the lowest point being only 0.55 mm, resulting in a decrease in structural strength.

[0114] Geometric deformation: After stretching, the flatness of the inner liner and the verticality of the sidewalls deviate significantly, with an average flatness deviation of 0.3 mm and an average verticality deviation of 0.25°. This requires extensive subsequent reshaping and repair, which is difficult and makes it hard to fully restore the design accuracy.

[0115] Production efficiency: Although the single-piece molding time is fast (about 60 seconds), the actual output efficiency of qualified products is lower than that of this invention due to the high scrap rate and a large amount of subsequent repair work.

[0116] Material utilization rate: The waste rate (including scrap rate) is as high as 25% or more.

[0117] The following is a comparison of key performance parameters between the embodiments of the present invention and the comparative examples:

[0118] Example 1 Comparative Example 2 Sheet thickness (mm) 0.8 0.8 Key dimension deviation (mm) Average 0.11 Average 0.35 (0.5 at the corner) Weld shear strength (MPa) Average 150 N / A (conventional stretching without weld) Weld leakage rate (%) 0 N / A Side wall thickness reduction rate (%) 0 (integrally formed, no reduction) 31.25 (0.8 mm -> 0.55 mm) Surface defect rate (%) <0.5 (slight indentation can be repaired) > 20 (wrinkling, cracking, severe stretching marks) Flatness deviation (mm) Average 0.08 Average 0.3 Side wall perpendicularity deviation (°) Average 0.07 Average 0.25 Single piece production cycle (s) 85 60 (but requires a lot of rework) Material utilization rate (scrap rate) 12% 25% Subsequent repair workload Extremely small Large and difficult to completely eliminate defects

[0119] As shown in Table 1:

[0120] Both Example 1 and Comparative Example 1 used 0.8 mm thick AL5052 aluminum alloy sheets. However, Example 1 ensured that the sheet thickness was uniformly distributed during the forming process without significant thinning. This was due to the stress-guiding effect of the arc-shaped positioning groove 3, which dispersed local stress during bending, preventing excessive stretching of the material and thus maintaining the molecular structure integrity of the original sheet. The grain arrangement of the aluminum alloy remained relatively stable during stamping, reducing the generation of dislocations and microcracks.

[0121] In contrast, Comparative Example 1 uses a traditional stamping and stretching process. Due to the deep stretching (280 mm) and right-angle transition, the material is subjected to extremely high tensile stress at the corner, resulting in grain slippage and necking. The wall thickness is severely reduced (to a minimum of 0.55 mm), which destroys the uniformity of the material and reduces the overall structural strength.

[0122] The average critical dimension deviation in Example 1 is only 0.11 mm. This is because the stamping and bending process combines high-precision CNC stamping equipment (tolerance control ±0.04 mm) and real-time closed-loop control of a multi-axis CNC bending machine (accuracy ±0.1°). The arc-shaped positioning groove 3 serves as a preset deformation guide point, which uniformly releases stress during the bending process, reduces material springback, and ensures the stability of geometric dimensions.

[0123] The dimensional deviation of Comparative Example 1 averaged 0.35 mm, and even 0.5 mm in some areas. This was due to the inherent defects of the stretching process: the material was subjected to uneven stress distribution during stretching, resulting in a significant springback effect. Uneven deformation occurred during the grain rearrangement process. In addition, the limited precision of the mold made it difficult to control the dimensions, which increased residual stress at the molecular level and affected the assembly accuracy and sealing performance.

[0124] The shear strength of the weld in Example 1 is as high as 150 MPa, far exceeding the industry standard (100 MPa). This is attributed to the application of the automated laser welding system. The high energy density (power density 10^6 W / cm²) of laser welding achieves deep penetration welding, enabling the flanged welding plate 4 and the main plate 1 to form a metallurgical bond. The intermolecular diffusion is sufficient, the grains in the weld area are refined, and the heat-affected zone (HAZ width is only 0.45 mm) is reduced, thereby improving the strength. The laser parameters (such as 2.6 kW power and 3.2 m / min speed) optimize the heat input and avoid oxidation and porosity of the aluminum alloy.

[0125] Comparative Example 1 does not describe the welding process in detail, but traditional stretching processes are often accompanied by subsequent welding. Due to large dimensional deviations and surface defects, the weld joints are mismatched, resulting in low weld strength, insufficient molecular bonding, and easy occurrence of incomplete fusion or porosity, making it difficult to guarantee strength.

[0126] The weld leakage rate of Example 1 is 0%. This is due to the gapless overlap (gap ≤ 0.04 mm) of the first positioning block 6 and the second positioning block 7 and the control of laser welding. The positioning blocks ensure the tight fit of the welding area 8. Laser welding forms a continuous and dense weld. The removal of oxides at the molecular level (through surface treatment) and the use of protective gas (argon) prevent pores and cracks. Internally, the oxide film of the aluminum alloy is effectively destroyed and a dense layer is reformed, which enhances the sealing performance.

[0127] In contrast, Comparative Example 1 suffers from dimensional deviations and surface defects (such as microcracks) caused by the stretching process. During welding, the joints are uneven, gaps are easily generated, stress concentration exists at the molecular level, the risk of leakage is high, and subsequent repairs are difficult to completely eliminate the leakage points.

[0128] The sidewall thickness of Example 1 is uniform, with an extremely low thinning rate and integral molding without thinning; while the sidewall thickness thinning rate of Comparative Example 1 is as high as about 31.25% (from 0.8 mm to 0.55 mm). This is because the material is subjected to bidirectional tensile stress at the corner during the stretching process, which leads to intergranular slippage and thickness reduction, weakening the material's toughness and increasing the risk of breakage.

[0129] The low surface defect rate in Example 1 is attributed to the control of the stamping and bending process and the surface pre-passivation treatment. Pre-passivation forms a 1.0 μm thick amorphous oxide film to protect the substrate, while the arc-shaped positioning groove 3 reduces stress concentration during bending, preventing wrinkling and cracking.

[0130] In contrast, the surface defect rate of Comparative Example 1 reached 15% (scrap rate) because the stretching process easily produces wrinkles, orange peel texture and microcracks at the corners. This is due to uneven material flow, which leads to surface roughness and defects that are difficult to repair later.

[0131] The average flatness deviation of Example 1 is 0.08 mm, which is achieved through the uniform stress distribution of the finishing process (S50) and bending process. During bending, the arc-shaped positioning groove 3 guides deformation, reduces residual stress, and ensures neat arrangement of grains at the molecular level, preventing warping.

[0132] The average flatness deviation of Comparative Example 1 was 0.3 mm, which was due to uneven rebound and stress release after stretching, high residual stress inside the molecules, resulting in planar deformation, a large amount of repair work and limited effect.

[0133] The sidewall verticality deviation of Example 1 is 0.07° on average, thanks to the angle control (±0.1°) of the multi-axis CNC bending machine and the guidance of the arc-shaped positioning groove 3; while the deviation of Comparative Example 1 is 0.25° on average, due to the uncontrollable material flow of the stretching process and the disordered grain orientation at the molecular level, resulting in verticality loss and affecting assembly.

[0134] Example 1 has a single-piece production cycle of 85s, which is highly efficient because the stamping and bending process is formed in one step, reducing subsequent repairs. In contrast, although the single-piece forming time of Comparative Example 1 is short (60s), the high scrap rate and repair work result in low actual efficiency. Although there is no direct correlation at the molecular level, the unstable process leads to wasted time.

[0135] Example 1 has a material scrap rate of 12%, achieved through integrated stamping and optimized material routing, reducing waste. There is no significant impact at the molecular level, but the process is economically efficient. In contrast, Comparative Example 1 has a scrap rate of 25%, resulting in significant material loss due to high stretching scrap rates and trimming requirements.

[0136] The subsequent repair work in Example 1 was minimal, requiring only minor adjustments for fine-tuning, thanks to the precision of the process. Molecular-level stress control was excellent. In contrast, Comparative Example 1 involved a large amount of repair work, requiring reshaping and patching due to numerous defects and severe molecular damage.

[0137] In summary, it is clear from the data comparison between the above embodiments and comparative examples that the stamping and bending process of the inner liner of the vehicle refrigerator, by integrating the arc-shaped positioning groove 3 and the self-aligning positioning block on the flat prefabricated part, and combining high-precision CNC stamping, multi-axis CNC bending and automated laser welding technology, fundamentally solves the bottlenecks in precision, quality and efficiency faced by existing technologies in the integrated molding of complex three-dimensional structures of thin-walled metal sheets.

[0138] The arc-shaped positioning groove 3 plays a role in stress guidance and release during the bending process, effectively avoiding wrinkling and cracking of the material, and ensuring the bending radius and uniform wall thickness, thereby ensuring the structural integrity and strength of the inner liner. The matching setting of the first positioning block 6 and the second positioning block 7 provides a reliable self-alignment mechanism for the flanged welding plate 4, ensuring gapless overlap and high-strength connection of the welding interface, greatly improving the reliability and sealing of the welding.

[0139] The process significantly improves the production efficiency, material utilization rate, and product qualification rate of the inner liner of the vehicle refrigerator. At the same time, it enables a thinner and more aesthetically pleasing inner liner design, and greatly reduces the mold design and manufacturing costs as well as subsequent processing and correction costs.

[0140] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A car refrigerator liner, comprising: The integrally molded main structure is characterized by; The main structure includes: a main board (1), a flanged side frame (2) set on the top edge of the main board (1), and a plurality of arc-shaped positioning grooves (3) opened on the top of the side frame, the plurality of arc-shaped positioning grooves (3) being located in the bending connection area between the flanged side frame (2) and the main board (1). The motherboard (1) has a flanged welding plate (4) on one side edge, and a number of mounting ears (5) are provided at the bottom of the motherboard (1). The flanged welding plate (4) has a first positioning block (6) at the bottom edge area of ​​the flanged welding plate (4). The motherboard (1) has a second positioning block (7) on the opposite side from the first positioning block (6). The geometry of the second positioning block (7) matches that of the first positioning block (6). When the flanged welding plate (4) overlaps with the motherboard (1) by bending, the first positioning block (6) and the second positioning block (7) coincide. After the first positioning block (6) and the second positioning block (7) overlap, the lap joint formed by the side edge of the flanged welding plate (4) and the outer surface of the main board (1) constitutes the welding area (8).

2. The inner liner of a vehicle refrigerator according to claim 1, characterized in that: The thickness of the motherboard (1) is 0.6-1.2 mm, the material of the motherboard (1) is aluminum alloy sheet, and the surface of the motherboard (1) is pre-passivated.

3. A vehicle refrigerator liner according to claim 1, characterized in that: The flanged side frame (2) extends upward along the circumferential edge of the main board (1) and is formed by bending process. The height of the flanged side frame (2) corresponds to the depth of the inner liner of the car refrigerator. The connection between the flanged side frame (2) and the main board (1) forms a rounded corner transition structure with a specific inner bending radius. The inner bending radius of the rounded corner transition structure is in the range of 1.5-3.0 mm.

4. A vehicle refrigerator liner according to claim 1, characterized in that: The arc-shaped positioning groove (3) has a semi-circular or elliptical cross-section. The depth of the arc-shaped positioning groove (3) is 0.3-0.6 times the thickness of the main board (1). The arc of the arc-shaped positioning groove (3) matches the preset bending angle and is used to guide the deformation trajectory of the material during the bending process.

5. A vehicle refrigerator liner according to claim 1, characterized in that: The thickness of the flanged welding plate (4) is the same as that of the flanged side frame (2), and the material, thickness and surface treatment process of the flanged welding plate (4) are the same as those of the main board (1).

6. A vehicle refrigerator liner according to claim 1, characterized in that: The first positioning block (6) is a trapezoidal protrusion structure, and the second positioning block (7) is a trapezoidal protrusion structure that matches the first positioning block (6). The depth and width of the second positioning block (7) correspond to those of the first positioning block (6). The first positioning block (6) is located above the second positioning block (7). The length of the welding area (8) is the same as the effective overlap length of the flanged welding plate (4).

7. A stamping and bending process for a vehicle refrigerator liner, used to manufacture the vehicle refrigerator liner according to any one of claims 1-6, characterized in that, Includes the following steps; S10: Obtain a metal plate of a preset size, stamp it, and form a flat prefabricated part with a main board (1), a flanged side frame (2), an arc-shaped positioning groove (3), a flanged welding plate (4), a mounting ear (5), a first positioning block (6), and a second positioning block (7) in one go; S20: The first bending of the flat precast component is performed to form the initial standing edge of the flanged side frame (2) and the flanged welding plate (4); S30: Perform a second bend on the semi-finished product after the first bend, so that the corresponding edges of the flanged welding plate (4) and the main plate (1) overlap and the first positioning block (6) and the second positioning block (7) coincide. S40: Weld the welding area (8) to form a solid inner liner structure; S50: Perform fine finishing on the welded inner liner to correct any existing geometric deformation; S60: Remove any temporary auxiliary supports or positioning structures formed during bending or welding. S70: Perform surface treatment on the welding area (8) to remove welding spatter and oxides, and perform smoothing treatment on other surfaces.

8. The stamping and bending process for the inner liner of a vehicle refrigerator according to claim 1, characterized in that: In S10, the stamping process is completed using high-precision CNC stamping equipment and progressive or compound dies to ensure that all features on the flat preform are formed in one step. The die material is high-strength wear-resistant steel and undergoes heat treatment.

9. A stamping and bending process for the inner liner of a vehicle refrigerator according to claim 1, characterized in that: In S30, the second bending is performed by a multi-axis CNC bending machine. The arc-shaped positioning groove (3) serves as a stress concentration point and deformation guide point to ensure that the material bends uniformly along the preset trajectory. The bending angle needs to be controlled in real time with a closed loop, and the downward stroke of the upper die is controlled so that the first positioning block (6) and the second positioning block (7) can overlap without gap, and the overlap gap is controlled within 0.05mm.

10. A stamping and bending process for the inner liner of a vehicle refrigerator according to claim 1, characterized in that: In S40, the welding process is performed using an automated laser welding system.

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