Sheet metal part wrap angle bending die frame

Abstract

The invention relates to the technical field of sheet metal part bending machining, in particular to a sheet metal part wrap angle bending die frame which comprises a box body, two side seats are fixed to the left side and the right side of the box body respectively, a bending mechanism facilitating different sheet metal part wrap angles is arranged on the upper side of the box body, and an adjusting mechanism used for adjusting the positions of the sheet metal parts is arranged in the box body. According to the sheet metal part wrap angle bending die frame and the adjusting mechanism, a double-shaft motor drives a supporting plate to drive a push rod to achieve accurate adjustment and control of the left-right position of a sheet metal part, a supporting air bag dynamically adjusts the working height of the push rod through inflation and deflation, the push rod is lifted during inflation so as to adapt to workpieces with different thicknesses and provide stable pushing force, and the push rod is retracted during deflation so as to avoid interference; in the bending mechanism, an air cylinder B drives a push plate to be matched with a rubber sheet to finish front-back position fine adjustment and flexible clamping and fixing. And the push rod is in linkage fit with the push plate, so that the sheet metal part can be steplessly positioned to any bending area corresponding to four folding angle sections (45 degrees / 60 degrees / 90 degrees / 120 degrees) in a horizontal plane.

Description

Technical Field

[0001] This invention relates to the field of sheet metal bending processing technology, specifically to a sheet metal corner bending mold frame. Background Technology

[0002] Sheet metal parts, as fundamental structural components widely used in industrial manufacturing (such as chassis, cabinets, electrical enclosures, and support frames), have their corner bending process quality directly affecting the assembly accuracy, structural strength, and appearance quality of the product. In the production of complex sheet metal components, it is often necessary to precisely bend multiple corners of the same workpiece at different angles (such as 45°, 60°, 90°, and 120°) to achieve three-dimensional covering and forming. This process requires high positioning repeatability, flexible angle adaptation, and effective prevention of deformation, scratches, or springback defects in the sheet metal during stress, placing high demands on the structural design and process adaptability of bending equipment.

[0003] Currently, the industry mainstream uses CNC hydraulic bending machines in conjunction with specialized punch and concave dies to complete sheet metal bending operations. A typical machine consists of a frame, a slide block, an upper die (punch), and a lower die (concave). A hydraulic cylinder drives the slide block downwards, causing the sheet metal part to plastically deform within the die cavity. For multi-angle corner requirements, existing solutions mostly rely on the following methods: first, configuring multiple sets of angle die libraries, requiring manual die changes during processing; second, using adjustable angle universal dies, but requiring repeated adjustments to the die opening and closing angles and positioning references; while some high-end machines integrate turret-type die libraries, their complex structure and high cost, and die changes still require interrupting the production process. Furthermore, workpiece positioning largely relies on manually placing positioning pins or simple stops, lacking dynamic position compensation capabilities.

[0004] However, existing bending equipment has significant drawbacks in practical applications: First, multi-angle processing is inefficient—a single mold is only suitable for a fixed bending angle. When dealing with scenarios where multiple angles need to be wrapped on the same workpiece, the mold must be disassembled and reassembled multiple times, and the workpiece must be clamped repeatedly. This is not only time-consuming and labor-intensive, but also causes misalignment of the bending line and angle deviation due to the cumulative error from multiple positioning. Second, workpiece support and protection are insufficient—traditional rigid molds are in direct hard contact with sheet metal parts, which can easily cause surface indentations, local dents, or wrinkles at the bending point when bending thin plates or high-precision parts. Furthermore, there is a lack of an adaptive buffering mechanism for workpiece deformation under stress. Third, positioning adjustment relies on manual experience. Fine adjustments to the workpiece position require visual calibration by the operator. There is a lack of automated, high-precision real-time position compensation structures, making it difficult to guarantee the repeatability of positioning accuracy in small-batch, multi-variety production. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a sheet metal corner bending mold frame, which has advantages such as continuous bending of corners at multiple angles, and solves the problem of large cumulative positioning errors caused by repeated mold disassembly and assembly and repeated clamping in traditional bending equipment.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a sheet metal corner bending mold frame, comprising a box body, two side seats fixed on both the left and right sides of the box body, a bending mechanism for facilitating different sheet metal corners provided on the upper side of the box body, and an adjustment mechanism for adjusting the position of the sheet metal parts provided inside the box body;

[0007] The bending mechanism includes four bends at different angles formed by bending on four side seats. Support seats are fixed on opposite sides of the left and right side seats. The same linear module is fixed to the upper side of the two support seats via support rods. A mounting plate is fixed to the upper surface of the slider on the linear module. Two hanging rods are vertically fixed inside the mounting plate. The same horizontal base plate is fixed to the lower surface of the two hanging rods. A cylinder A is fixed to the upper surface of the base plate. A bending frame is fixed to one end of the output shaft of the cylinder A. A rotating wheel is rotatably connected to the bending frame via a rotating shaft.

[0008] Furthermore, the bending mechanism also includes side plates fixed to the front and rear sides of the housing, cylinder B is fixed on one side of each of the two side seats, push plate is fixed on one end of the output shaft of each of the two cylinders B, and rubber sheet is fixed on one side of each of the two push plates.

[0009] Furthermore, the adjustment mechanism includes support plates fixed to the inner walls of the left and right sides of the housing. A base plate is fixed between the inner walls of the left and right sides of the housing and on the upper surface of the two support plates. A dual-axis motor is fixed at the center of the upper surface of the base plate. Two symmetrical sub-plates are fixed on the upper surface of the support plates. Support blocks are fixedly connected to the inner walls of the left and right sides of the housing. Drive rods are rotatably connected between the two sub-plates and the two support blocks through bearings. The output shafts at both ends of the dual-axis motor are driven by pulleys to the two drive rods. Support plates are threaded to the outer sides of the two drive rods. Multiple positioning rods that move linearly up and down are slidably connected inside the support plates. Push rods are fixed to one end of each positioning rod on the left and right sides. Support airbags are fixed between the positioning rods and push rods on the same vertical line.

[0010] Furthermore, the adjustment mechanism also includes two sliding pieces on the lower surfaces of the support plates, a sliding groove is provided on the upper surface of the base plate, and the sliding pieces move linearly within the sliding groove. A push groove is provided on the upper surface of the housing, and the push rod moves linearly left and right within the push groove.

[0011] Furthermore, the adjustment mechanism also includes an air pump fixed to the upper surface of the base plate. The air outlet of the air pump is connected to a connecting pipe, and the connecting pipe is connected to two supporting airbags. Two control valves are sleeved on the outside of the connecting pipe.

[0012] Furthermore, the mounting plate faces the box body and is arranged parallel to the top surface of the box body, and the sum of the widths of the two side seats is less than the width of the box body.

[0013] Furthermore, the bending angles of the four bend segments are different, with angle values ​​of 45°, 60°, 90° and 120° respectively, and the bending profile of each bend segment is adapted to the motion trajectory of the corresponding wheel.

[0014] Furthermore, the angled section and the side seat are modularly detachable. The side seat has a positioning groove, and the bottom of the angled section has a positioning boss that fits into it, and is fixed by locking bolts.

[0015] Furthermore, the outer peripheral working surface contour of the wheel is consistent with the bending radius of the corresponding bend segment, and the surface is covered with a 2mm thick polyurethane buffer layer.

[0016] Furthermore, the working contact surface of the corner segment is provided with a hard alloy weld overlay layer, and the inner wall of the box is provided with an angle marking nameplate corresponding to each corner segment position.

[0017] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0018] 1. In this sheet metal corner bending die frame, the adjustment mechanism uses a dual-axis motor to drive a support plate and a push rod to precisely control the left and right position of the sheet metal part. The support airbag dynamically adjusts the working height of the push rod by inflation and deflation—raising the push rod when inflated to accommodate workpieces of different thicknesses and provide stable pushing force, and retracting it when deflated to avoid interference. In the bending mechanism, cylinder B drives a push plate in conjunction with a rubber sheet to complete fine-tuning of the front and back positions and flexible clamping. The linkage between the push rod and the push plate allows the sheet metal part to be steplessly positioned in the horizontal plane to any bending area corresponding to the four corner segments (45° / 60° / 90° / 120°). A single clamping can continuously complete multi-angle corner bending, completely eliminating the cumulative positioning error and production interruption caused by repeated clamping in traditional processes, and significantly improving the bending accuracy and processing efficiency of complex structural parts.

[0019] 2. This sheet metal corner bending die set features a flexible contact system formed by the rubber sheet at the push plate end and the polyurethane buffer layer of the rotating wheel, providing front-to-back clamping and up-and-down pressing. This effectively prevents surface indentations, wrinkles, or springback deformation of the sheet metal parts. The height adaptive adjustment of the support airbag not only ensures reliable pushing of the push rod onto thin / thick plate workpieces but also provides elastic support during bending, significantly suppressing local instability of thin plate parts. Simultaneously, the modular quick-change structure of the corner section, combined with the angle marking nameplate on the inner wall of the housing, makes station switching intuitive and error-proof. The entire design eliminates the need for a high-cost turret mold library, achieving multi-angle flexible bending through a compact and integrated design, reducing equipment costs by over 40%. It is particularly suitable for high-precision corner bending production of small batches and various types of sheet metal parts, combining process reliability, ease of operation, and economic practicality. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention;

[0021] Figure 2 This is a schematic diagram of the bending mechanism of the present invention;

[0022] Figure 3 This is a schematic diagram of the angled segment structure of the present invention;

[0023] Figure 4 This is a schematic diagram of the adjustment mechanism structure of the present invention.

[0024] In the diagram: 1. Housing, 2. Side seat, 3. Bending mechanism, 31. Corner section, 32. Support base, 33. Linear module, 34. Mounting plate, 35. Hanging rod, 36. Base plate, 37. Cylinder A, 38. Bending frame, 39. Rotary wheel, 310. Side plate, 311. Cylinder B, 312. Push plate, 313. Rubber sheet, 4. Adjustment mechanism, 41. Support plate, 42. Base plate, 43. Dual-axis motor, 44. Dividing plate, 45. Support block, 46. Drive rod, 47. Support plate, 48. Positioning rod, 49. Push rod, 410. Support airbag, 411. Sliding plate, 412. Air pump, 413. Connecting pipe. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Please see Figure 1-4 In this embodiment, a sheet metal corner bending mold frame includes a box body 1. Two side seats 2 are fixed on both the left and right sides of the box body 1. A bending mechanism 3 is provided on the upper side of the box body 1 to facilitate the corner bending of different sheet metal parts. An adjustment mechanism 4 for adjusting the position of the sheet metal parts is provided inside the box body 1.

[0027] The bending mechanism 3 includes four bend segments 31 formed by bending at different angles on the side seats 2. Support seats 32 are fixed on the opposite sides of the left and right side seats 2. The same linear module 33 is fixed on the upper side of the two support seats 32 via support rods. The upper surface of the slider on the linear module 33 is fixed with a mounting plate 34. Two hanging rods 35 are vertically fixed inside the mounting plate 34. The same horizontal base plate 36 is fixed on the lower surface of the two hanging rods 35. A cylinder A37 is fixed on the upper surface of the base plate 36. A bending frame 38 is fixed at one end of the output shaft of the cylinder A37. A rotating wheel 39 is rotatably connected to the bending frame 38 via a rotating shaft.

[0028] It should be noted that, through the coordinated layout of the housing 1, side seat 2, bending mechanism 3 integrating multi-angle bending segment 31, and adjustment mechanism 4 including push rod 49 and support airbag 410, a single-machine multi-station bending system is constructed, realizing the full-process positioning and bending of sheet metal parts under a single clamping, fundamentally solving the core problems of large cumulative positioning errors and low production efficiency caused by repeated clamping of traditional equipment.

[0029] The bending mechanism 3 also includes side plates 310 fixed to the front and rear sides of the housing 1. A cylinder B311 is fixed on one side of each of the two side plates. A push plate 312 is fixed at one end of the output shaft of each of the two cylinders B311. A rubber sheet 313 is fixed on one side of each of the two push plates 312.

[0030] It should be noted that the side plate 310, cylinder B311, push plate 312 and rubber sheet 313 constitute a flexible front and rear clamping unit. The rubber sheet 313 provides buffer contact to avoid scratches, and the push plate 312 precisely limits the workpiece displacement, significantly improving the positioning stability and surface integrity during the bending process.

[0031] The adjustment mechanism 4 includes support plates 41 fixed to the inner walls of the left and right sides of the housing 1. A base plate 42 is fixed between the inner walls of the left and right sides of the housing 1 and on the upper surface of the two support plates 41. A dual-axis motor 43 is fixed at the center of the upper surface of the base plate 42. Two symmetrical partition plates 44 are fixed on the upper surface of the support plates 41. Support blocks 45 are fixedly connected to the inner walls of the left and right sides of the housing 1. The two partition plates 44 are rotatably connected to the two support blocks 45 through bearings. The output shafts at both ends of the dual-axis motor 43 are driven by belt pulleys to the two drive rods 46. Support plates 47 are threadedly connected to the outer sides of the two drive rods 46. Multiple positioning rods 48 that move linearly up and down are slidably connected inside the support plates 47. Push rods 49 are fixed to one end of the positioning rods 48 on both sides. Support airbags 410 are fixed between the positioning rods 48 and the push rods 49 on the same vertical line.

[0032] It should be noted that the dual-axis motor 43 drives the drive rod 46 to move the support plate 47 linearly, and the linkage positioning rod 48 and push rod 49 realize precise control of the left and right positions. With the elastic support of the support airbag 410, sheet metal parts of different thicknesses can obtain suitable height and stable pushing force, which greatly enhances the positioning accuracy and process universality.

[0033] The adjustment mechanism 4 also includes sliding pieces 411 on the lower surface of two support plates 47, a sliding groove on the upper surface of the base plate 42, and the sliding pieces 411 move linearly in the sliding groove. A push groove is provided on the upper surface of the housing 1, and the push rod 49 moves linearly left and right in the push groove.

[0034] It should be noted that the sliding piece 411 on the lower surface of the support plate 47 is embedded in the guide groove of the base plate 42, and the push rod 49 is constrained to move within the push groove of the housing 1. The dual guide structure effectively eliminates running sway and offset, ensures that the adjustment mechanism 4 moves smoothly and accurately, and improves the reliability of the system's repeatability positioning.

[0035] The adjustment mechanism 4 also includes an air pump 412 fixed to the upper surface of the base plate 42. The air outlet of the air pump 412 is connected to a connecting pipe 413, and the connecting pipe 413 is connected to and fixed to two supporting airbags 410. Two control valves are sleeved on the outside of the connecting pipe 413.

[0036] It should be noted that the air pump 412 is connected to the support airbag 410 via the connecting pipe 413. In conjunction with the control valve, the inflation and deflation volume is precisely controlled, so that the height of the push rod 49 dynamically adapts to the thickness of the sheet metal part, providing elastic support force during bending and effectively suppressing the deformation and springback defects of the thin sheet metal part.

[0037] The mounting plate 34 faces the housing 1 and is parallel to the top surface of the housing 1. The sum of the widths of the two side seats 2 is less than the width of the housing 1.

[0038] It should be noted that the mounting plate 34 is set parallel to the top surface of the housing 1, and the total width of the two side seats 2 is less than the width of the housing 1. The spatial layout of the bending mechanism 3 is optimized to ensure the stability of the vertical pressing trajectory of the rotating wheel 39. At the same time, a workpiece transfer channel is reserved to improve the smoothness of operation and the convenience of operation.

[0039] The four bend segments 31 have different bending angles, with angle values ​​of 45°, 60°, 90° and 120° respectively, and the bending profile of each bend segment 31 is adapted to the motion trajectory of the corresponding wheel 39.

[0040] It should be noted that the four bend segments 31 are preset with bending angles of 45°, 60°, 90° and 120° respectively. Their bending profiles are precisely matched with the movement trajectory of the rotary wheel 39, realizing continuous bending of multiple bends at a single clamping, and completely avoiding production interruptions and reference conversion errors caused by mold changes.

[0041] The angle section 31 and the side seat 2 are modularly detachable. The side seat 2 is provided with a positioning groove, and the bottom of the angle section 31 is provided with a positioning boss that fits into it and is fixed by locking bolts.

[0042] It should be noted that the bottom positioning boss of the angle section 31 is embedded in the positioning groove of the side seat 2 and fixed by the locking bolt to form a modular quick-change structure, which facilitates the quick replacement of angle sections 31 at different angles and significantly improves the equipment's flexibility and maintenance efficiency.

[0043] The outer working surface contour of the rotating wheel 39 is consistent with the bending radius of the corresponding angle segment 31, and the surface is covered with a polyurethane buffer layer with a thickness of 2mm.

[0044] It should be noted that the outer periphery of the roller 39 is strictly consistent with the bending radius of the bend segment 31, and the surface is covered with a 2mm polyurethane buffer layer to create a "rigid and flexible" contact interface. This ensures the accuracy of the bending profile while avoiding indentations and wrinkles, significantly improving the surface quality and forming consistency of the workpiece.

[0045] The working contact surface of the corner section 31 is provided with a hard alloy weld overlay layer, and the inner wall of the box 1 is provided with an angle marking nameplate corresponding to the position of each corner section 31.

[0046] It should be noted that the hard alloy layer is welded onto the working surface of the angled section 31 to enhance wear resistance and life. An angle marking nameplate is set at the corresponding position on the inner wall of the box 1 to achieve intuitive identification of the workstation and prevent wrong operation, taking into account both component durability and human-machine operation efficiency, and reducing the risk of misoperation.

[0047] The working principle of the above embodiments is as follows:

[0048] First, the sheet metal part to be bent is placed on the upper surface of the housing 1, and the adjustment mechanism 4 is started for precise positioning: the dual-axis motor 43 runs, and drives two drive rods 46 synchronously through the pulley (the drive rods 46 are supported by bearings between the dividing plate 44 and the support block 45), converting the rotational motion into the linear displacement of the support plate 47 (the sliding piece 411 on the lower surface of the support plate 47 guides smoothly along the sliding groove of the bottom plate 42). The support plate 47 drives the slidably connected positioning rod 48 and push rod 49 to move synchronously, accurately adjusting the left and right position of the sheet metal part to the target bending area; at the same time, the cylinder B311 fixed on the side plate 310 in the bending mechanism 3 pushes the push plate 312 to move towards the front and rear sides of the workpiece, and the rubber piece 313 at the end of the push plate 312 flexibly clamps the sheet metal part, completing the front and rear positioning and anti-slip fixation.

[0049] Air pump 412 inflates support airbag 410 via connecting pipe 413. Support airbag 410 expands and lifts push rod 49, raising the sheet metal part to a working height that matches the contour of the bend segment 31 (the inflation amount is dynamically adjusted according to the sheet thickness). When resetting is required, deflation will cause push rod 49 to fall back. After positioning, linear module 33 drives mounting plate 34 to move along support rod on support base 32. Mounting plate 34 is connected to base plate 36 via hanger 35. Cylinder A37 on base plate 36 pushes bending frame 38 down, causing roller 39 to apply pressure along the pre-set bending contour of bend segment 31 on side seat 2, achieving precise corner bending. During bending, the polyurethane buffer layer on the outer periphery of roller 39 forms flexible contact with the hard alloy working surface of bend segment 31, effectively avoiding indentation, wrinkling, or springback. Support airbag 410 continuously provides adaptive support force to ensure the clarity of bending contour and dimensional stability.

[0050] If multiple bends (such as 45°, 60°, 90°, 120°) need to be completed on the same sheet metal part, the system uses the linkage between the push rod 49 and the push plate 312 to steplessly transfer the workpiece to the corresponding area of ​​the next bend segment 31. The rotating wheel 39 completes the bending of each angle in sequence. There is no need to disassemble the workpiece or change the mold throughout the process. After all the processes are completed, the support airbag 410 is deflated to retract the push rod 49, and the cylinder B311 drives the push plate 312 to release the clamp, so that the formed sheet metal part can be removed. The whole process relies on the coordinated control of the adjustment mechanism 4 and the bending mechanism 3 to realize multi-angle continuous bending in a single clamping. The positioning is accurate, the support is self-adaptive, and the surface protection is perfect, which significantly improves the processing efficiency, yield and equipment flexibility.

[0051] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sheet metal corner bending mold frame, comprising a box body (1), characterized in that: The box (1) has two side seats (2) fixed on both the left and right sides. The upper side of the box (1) is provided with a bending mechanism (3) to facilitate the corner wrapping of different sheet metal parts. The box (1) is provided with an adjustment mechanism (4) for adjusting the position of sheet metal parts. The bending mechanism (3) includes four side seats (2) with different angles formed by bending. Support seats (32) are fixed on opposite sides of the left and right side seats (2). The same linear module (33) is fixed on the upper side of the two support seats (32) by support rods. The upper surface of the slider of the linear module (33) is fixed with a mounting plate (34). Two hanging rods (35) are vertically fixed inside the mounting plate (34). The same horizontal base plate (36) is fixed on the lower surface of the two hanging rods (35). A cylinder A (37) is fixed on the upper surface of the base plate (36). A bending frame (38) is fixed at one end of the output shaft of the cylinder A (37). A rotating wheel (39) is rotatably connected to the bending frame (38) through a rotating shaft.

2. The sheet metal corner bending die frame according to claim 1, characterized in that: The bending mechanism (3) also includes side plates (310) fixed to the front and rear sides of the housing (1), and cylinders B (311) are fixed on the opposite side of the two side plates. Push plates (312) are fixed at one end of the output shaft of the two cylinders B (311), and rubber sheets (313) are fixed on the opposite side of the two push plates (312).

3. The sheet metal corner bending die frame according to claim 1, characterized in that: The adjustment mechanism (4) includes support plates (41) fixed to the inner walls of the left and right sides of the housing (1). A base plate (42) is fixed between the inner walls of the left and right sides of the housing (1) and on the upper surface of the two support plates (41). A dual-axis motor (43) is fixed at the center of the upper surface of the base plate (42). Two symmetrical partition plates (44) are fixed on the upper surface of the support plates (41). Support blocks (45) are fixedly connected to the inner walls of the left and right sides of the housing (1). The two partition plates (44) are respectively connected to the two support blocks (45). A drive rod (46) is rotatably connected between the two drive rods (46) via bearings. The output shafts at both ends of the dual-axis motor (43) are respectively driven by belt pulleys to the two drive rods (46). The outer sides of the two drive rods (46) are threadedly connected to support plates (47). Multiple positioning rods (48) that move linearly up and down are slidably connected inside the support plates (47). Push rods (49) are fixed at one end of the positioning rods (48) on both the left and right sides. A support airbag (410) is fixed between the positioning rods (48) and the push rods (49) on the same vertical line.

4. A sheet metal corner bending die frame according to claim 3, characterized in that: The adjustment mechanism (4) also includes two sliding pieces (411) on the lower surface of the support plates (47), the upper surface of the base plate (42) is provided with a sliding groove, and the sliding piece (411) moves linearly in the sliding groove. The upper surface of the box (1) is provided with a push groove, and the push rod (49) moves linearly left and right in the push groove.

5. A sheet metal corner bending die frame according to claim 3, characterized in that: The adjustment mechanism (4) also includes an air pump (412) fixed to the upper surface of the base plate (42). The air outlet of the air pump (412) is connected to a connecting pipe (413), and the connecting pipe (413) is connected to two supporting airbags (410). Two control valves are sleeved on the outside of the connecting pipe (413).

6. The sheet metal corner bending die frame according to claim 1, characterized in that: The mounting plate (34) faces the box (1) and is arranged parallel to the top surface of the box (1). The sum of the widths of the two side seats (2) is less than the width of the box (1).

7. A sheet metal corner bending die frame according to claim 1, characterized in that: The bending angles of the four bend segments (31) are different, with angle values ​​of 45°, 60°, 90° and 120° respectively, and the bending profile of each bend segment (31) is adapted to the motion trajectory of the corresponding wheel (39).

8. A sheet metal corner bending die frame according to claim 1, characterized in that: The angle segment (31) and the side seat (2) are modularly detachable. The side seat (2) has a positioning groove, and the bottom of the angle segment (31) has a positioning boss that fits into it and is fixed by locking bolts.

9. A sheet metal corner bending die frame according to claim 1, characterized in that: The outer working surface contour of the wheel (39) is consistent with the bending radius of the corresponding bend segment (31), and the surface is covered with a polyurethane buffer layer with a thickness of 2mm.

10. A sheet metal corner bending die frame according to claim 1, characterized in that: The working contact surface of the corner section (31) is provided with a hard alloy weld overlay layer, and the inner wall of the box body (1) is provided with an angle marking nameplate corresponding to the position of each corner section (31).

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