Portable drawing device for environmental art design

By designing portable, foldable and extendable drawing devices, the problems of inconvenience in carrying and structural fixing of existing drawing devices are solved, and the support and operational convenience of multi-size drawing paper is achieved, and the practicality and safety of environmental art design is improved.

CN120080661AInactive Publication Date: 2025-06-03QIANDONGNAN INSTITUTE OF TECHNOLOGY VOCATIONAL COLLEGE
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Patent Information

Application Number
CN202510301517.2
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-03-14
Publication Date
2025-06-03
Estimated Expiration
Not applicable · inactive patent

AI Technical Summary

Technical Problem

The existing drawing devices have a large structure and are difficult to store, are inconvenient to carry, and have a fixed structure, so they can only be adapted to paper of a specific size, which is less practical.

Method used

A portable environmental art design drawing device is designed, including a foldable drawing support plate and a support frame. The flexible connection of the drawing support plate is achieved through the connecting pin and the connecting rod. Combined with the use of the extendable extension plate and magnetic buckle, the support of multi-size drawing paper is achieved, and the practicality and safety of the device are improved through the door sealing structure and magnetic suction plate.

Benefits of technology

The portability and versatility of the device are realized, and users can easily carry and use it through folding and unfolding structures, adapting to different sizes of drawing paper, improving the convenience and safety of the designer in different environments.

✦ Generated by Eureka AI based on patent content.

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Abstract

The invention belongs to the technical field of art design, and particularly relates to a portable drawing device for environmental art design, which comprises an upper storage box and a drawing support plate arranged at the upper part of the upper storage box, the bottom of the upper storage box is fixedly connected with a lower storage box, and the lower storage box is used for storing drawing tools. A door sealing structure is arranged on the front portion of the lower storage box, a supporting frame and two straps distributed left and right are fixedly connected to the bottom of the lower storage box, and the supporting frame is located between the two straps; the drawing supporting plate and the supporting frame in the device are both arranged to be of a foldable structure, when the device is carried and used, the device can be folded and stored, the size of the device is reduced, and then the device can be carried very conveniently through the strap.
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Description

Technical Field

[0001] The present invention belongs to the technical field of art design, and specifically relates to a drawing device for portable environmental art design. Background Art

[0002] Environmental art design is a newly emerging design discipline that focuses on the art design of human living facilities and spatial environments. Before the 1980s, this discipline was mainly called interior art design, which mainly focused on the furnishings, layout, and decoration inside buildings, aiming to create a beautiful and suitable space for people to live, work, and live. However, with the development of the discipline, its concept has been extended to the overall design of outdoor spaces, large unit environmental design, the overall design of a region or urban environment, etc. In the process of environmental art design, drawing devices are essential tools for designers.

[0003] However, there are still many deficiencies in existing drawing devices. For example, existing drawing devices are large in structure and not easy to store, making them very inconvenient to carry, which limits their use by designers in different environments; and the structures of existing drawing devices are fixed, and they can only be adapted to draw on paper of a fixed size during use, making the practicality of drawing devices relatively low.

[0004] Therefore, in view of the above problems, a drawing device for portable environmental art design is proposed. Summary of the Invention

[0005] (I) Technical Problems to be Solved

[0006] In view of the deficiencies of the prior art, the present invention provides a drawing device for portable environmental art design, which solves the problems of inconvenient carrying of existing drawing devices and fixed structures that can only be applicable to paper of a specific size during use.

[0007] (II) Technical Solutions

[0008] To achieve the above object, the present invention provides the following technical solution: A drawing device for portable environmental art design, including an upper storage box and a drawing support plate arranged on the upper part of the upper storage box. The bottom of the upper storage box is fixedly connected to a lower storage box, which is used for storing drawing tools. A door closing structure is arranged at the front of the lower storage box. The bottom of the lower storage box is fixedly connected to a support frame and two shoulder straps distributed left and right, and the support frame is located between the two shoulder straps;

[0009] The upper storage box includes a first storage box body. Rear portions of the left and right side walls inside the first storage box body are each provided with a strip-shaped sliding groove. A connecting pin is slidably connected in each of the two strip-shaped sliding grooves. And two connecting support rods distributed left and right are provided at the rear side of the top of the first storage box body. The two connecting pins and the two connecting support rods are all used for connecting a drawing support plate. Two first magnetic sheets are fixedly connected to the front portion of the lower wall inside the first storage box body;

[0010] The drawing support plate includes a box-shaped plate, and the box-shaped plate is located inside the first storage box body. Middle portions of the left and right side faces of the box-shaped plate are each provided with a first connection hole, and the first connection hole is used for movably connecting a connecting support rod. Rear portions of the left and right side faces of the box-shaped plate are each provided with an annular sliding groove, and the annular sliding groove is used for connecting a connecting pin. Two second magnetic sheets are fixedly connected to the front side of the bottom of the box-shaped plate, and the two second magnetic sheets are magnetically connected to the two first magnetic sheets respectively.

[0011] Preferably, limiting sliding grooves are provided on both the left and right side walls inside the box-shaped plate, and an extension plate is slidably connected inside the box-shaped plate. Metal plates are provided on the end faces of the extension plate and the box-shaped plate for fixing drawing paper through magnetic clasps.

[0012] Preferably, a plurality of grooves are provided at equal intervals on the top of the extension plate, and rigid springs are fixedly connected to the lower walls of the plurality of grooves. A sleeve is fixedly connected to the tops of the plurality of rigid springs together. The sleeve is slidably connected to the box-shaped plate, and second sliders are fixedly connected to the rear portions of the left and right side faces of the sleeve. The two second sliders are respectively slidably connected to the two limiting sliding grooves.

[0013] Preferably, the connecting pin includes a fixed shaft, and first sliders are fixedly connected to both ends of the fixed shaft. The two first sliders are respectively located in the strip-shaped sliding groove and the annular sliding groove and are respectively slidably connected to the strip-shaped sliding groove and the annular sliding groove.

[0014] Preferably, the lower storage box includes a second storage box body, and the top of the second storage box body is fixedly connected to the bottom of the first storage box body. A storage groove is provided at the front opening of the second storage box body. Second connection holes are provided at the lower portions of the left and right side walls inside the storage groove. A third magnetic sheet is fixedly connected to the upper portion of the front side face of the second storage box body.

[0015] Preferably, the door closing structure includes a door panel, and the door panel is located inside the storage groove. A handle is fixedly connected to the upper portion of the front side face of the door panel, and the handle is used for pulling the door panel. A fourth magnetic sheet is fixedly connected to the upper portion of the rear side face of the door panel, and the fourth magnetic sheet is magnetically connected to the third magnetic sheet.

[0016] Preferably, a fixing rod is provided at the bottom of the door panel. The fixing rod is movably connected to the two second connection holes. The fixing rod is used for connecting the door panel and the second storage box body. Two torsion springs are sleeved outside the fixing rod, and the two torsion springs are used for automatic reset after the door panel is unfolded.

[0017] Preferably, the support frame includes a first n-shaped frame. Two movable rings are movably connected to the top of the first n-shaped frame, and both movable rings are fixedly connected to the front side of the bottom of the lower storage box. A second n-shaped frame is movably connected inside the first n-shaped frame. The second n-shaped frame and the first n-shaped frame are unfolded into an X shape to support the lower storage box.

[0018] Preferably, two arc-shaped clamping plates are snap-connected to the outside of the second n-shaped frame near the leg end. Both arc-shaped clamping plates are fixedly connected to the rear side of the bottom of the lower storage box, and the two arc-shaped clamping plates limit and block the top of the unfolded second n-shaped frame.

[0019] (III) Beneficial effects

[0020] Compared with the prior art, the present invention provides a drawing device for portable environmental art design, which has the following beneficial effects:

[0021] 1. In the present invention, both the drawing support plate and the support frame in the device are set to be foldable structures. When the device is carried and used, through folding and storage, the volume of the device can be reduced, and then the device can be very conveniently carried through the shoulder strap.

[0022] 2. In the present invention, the drawing support plate is set to be an extendable structure. When the device is used, the extension plate in the drawing support plate can be pulled. When the extension plate extends out of the box-shaped plate, it will automatically bounce up through the rigid spring, so that the surface is flush with the surface of the box-shaped plate, which can expand the use area of the drawing support plate and facilitate the device to perform drawing operations on drawing papers of multiple sizes.

[0023] 3. In the present invention, the drawing support plate and the upper storage box are connected by a connecting pin and a connecting rod. When the device is used, only need to lift the drawing support plate and pull the lower part of the drawing support plate forward, then the drawing support plate can be limited and supported by the connecting rod, making the operation of the device very convenient.

[0024] 4. In the present invention, a lower storage box is provided, and a door closing structure is provided at the front of the lower storage box. During the use of the device, the drawing paper and tools can be stored in the lower storage box, improving the practicability of the device. And the door closing structure can be attached to the lower storage box through the action of the magnetic sheet and the torsion spring to prevent the door closing structure from opening by itself. When the door closing structure is opened to take the tools inside the lower storage box, and then the door closing structure is released, the opening of the lower storage box can be blocked by the elastic automatic reset of the torsion spring, improving the use safety of the device.

[0025] 5. The present invention is provided with a support frame at the bottom of the lower storage box. When the device is carried, the support frame can be stored and will not occupy too much space. When the device is in use, the support frame can be directly unfolded to support the device for use, improving the convenience of the device during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are used to provide a further understanding of the present invention, and form a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0027] Figure 1 is a top view of the first form of the present invention;

[0028] Figure 2 is a bottom view of the first form of the present invention;

[0029] Figure 3 is a top view of the second form of the present invention;

[0030] Figure 4 is a bottom view of the second form of the present invention;

[0031] Figure 5 is a schematic perspective view of the upper storage box of the present invention;

[0032] Figure 6 is a schematic perspective view of the connecting pin of the present invention;

[0033] Figure 7 is a schematic exploded perspective view of the drawing support plate of the present invention;

[0034] Figure 8 is a schematic perspective view of the lower storage box of the present invention;

[0035] Figure 9 is a schematic perspective view of the door closing structure of the present invention;

[0036] Figure 10 is a schematic perspective view of the first form of the support frame of the present invention;

[0037] Figure 11 is a schematic perspective view of the second form of the support frame of the present invention.

[0038] In the figure: 1, upper storage box; 2, drawing support plate; 3, lower storage box; 4, door sealing structure; 5, support frame; 6, shoulder strap; 11, first storage box body; 12, strip chute; 13, connecting pin; 14, connecting rod; 15, first magnetic sheet; 131, fixed shaft; 132, first slider; 21, box-shaped plate; 22, first connecting hole; 23, annular chute; 24, limiting chute; 25, second magnetic sheet; 26, extension plate; 261, groove; 27, rigid spring; 28, housing; 29, second slider; 31, second storage box body; 32, storage groove; 33, second connecting hole; 34, third magnetic sheet; 41, door panel; 42, handle; 43, fourth magnetic sheet; 44, fixed rod; 45, torsion spring; 51, first n-shaped frame; 52, movable ring; 53, second n-shaped frame; 54, arc-shaped clamping plate. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] The following gives specific embodiments.

[0041] Please refer to Figures 1-11 , the present invention provides a portable drawing device for environmental art design, including an upper storage box 1 and a drawing support plate 2 arranged on the upper part of the upper storage box 1. The bottom of the upper storage box 1 is fixedly connected with a lower storage box 3 for storing drawing tools. A door sealing structure 4 is arranged at the front of the lower storage box 3. The bottom of the lower storage box 3 is fixedly connected with a support frame 5 and two shoulder straps 6 distributed left and right, and the support frame 5 is located between the two shoulder straps 6.

[0042] Furthermore, as Figures 1-7As shown in the figure, the upper storage box 1 includes a first storage box body 11. Rear parts of the left and right side walls inside the first storage box body 11 are both provided with strip-shaped sliding grooves 12. Connecting pins 13 are slidably connected in both of the two strip-shaped sliding grooves 12. And two connecting support rods 14 distributed left and right are provided at the rear side of the top of the first storage box body 11. The two connecting pins 13 and the two connecting support rods 14 are both used for connecting a drawing support plate 2. Two first magnetic attraction sheets 15 are fixedly connected to the front part of the lower wall inside the first storage box body 11. The drawing support plate 2 includes a box-shaped plate 21, and the box-shaped plate 21 is located inside the first storage box body 11. Middle parts of the left and right side surfaces of the box-shaped plate 21 are both provided with first connecting holes 22, and the first connecting holes 22 are used for movably connecting the connecting support rods 14. Rear parts of the left and right side surfaces of the box-shaped plate 21 are both provided with annular sliding grooves 23, and the annular sliding grooves 23 are used for connecting the connecting pins 13. Two second magnetic attraction sheets 25 are fixedly connected to the front side of the bottom of the box-shaped plate 21, and the two second magnetic attraction sheets 25 are magnetically connected to the two first magnetic attraction sheets 15 respectively. The connecting pin 13 includes a fixed shaft 131. First sliders 132 are fixedly connected to both ends of the fixed shaft 131. The two first sliders 132 are respectively located in the strip-shaped sliding groove 12 and the annular sliding groove 23, and are respectively slidably connected to the strip-shaped sliding groove 12 and the annular sliding groove 23.

[0043] Through the above solution: by setting the drawing support plate 2 in the device into a foldable structure, when the device is carried and used, through folding and storing, the volume of the device can be reduced, and then the device can be carried very conveniently through the shoulder strap 6.

[0044] Further, as Figure 7 shown in the figure, limiting sliding grooves 24 are both provided in the left and right side walls inside the box-shaped plate 21. And an extension plate 26 is slidably connected inside the box-shaped plate 21. Metal plates are arranged on the end faces of the extension plate 26 and the box-shaped plate 21 for fixing drawing paper through magnetic snap buttons. A plurality of grooves 261 distributed at equal intervals are provided at the top of the extension plate 26. And rigid springs 27 are fixedly connected to the lower walls of the plurality of grooves 261. A sleeve 28 is fixedly connected to the tops of the plurality of rigid springs 27 together. The sleeve 28 is slidably connected to the box-shaped plate 21. And second sliders 29 are fixedly connected to the rear parts of the left and right side surfaces of the sleeve 28 respectively. The two second sliders 29 are respectively slidably connected to the two limiting sliding grooves 24.

[0045] Through the above solution: by setting the drawing support plate 2 into an extendable structure, when the device is in use, the extension plate 26 in the drawing support plate 2 can be pulled. After the extension plate 26 extends out of the box-shaped plate 21, it will automatically bounce up through the rigid spring 27 to make the surface flush with the surface of the box-shaped plate 21, which can expand the use area of the drawing support plate 2 and facilitate the device to perform drawing operations on drawing papers of multiple sizes.

[0046] Further, as Figures 8-11As shown in the figure, the lower storage box 3 includes a second storage box body 31, and the top of the second storage box body 31 is fixedly connected to the bottom of the first storage box body 11. A storage groove 32 is provided at the front opening of the second storage box body 31. Second connecting holes 33 are provided at the lower parts of the left and right side walls inside the storage groove 32. A third magnetic attraction piece 34 is fixedly connected to the upper part of the front side of the second storage box body 31. The door closing structure 4 includes a door panel 41, and the door panel 41 is located inside the storage groove 32. A handle 42 is fixedly connected to the upper part of the front side of the door panel 41, and the handle 42 is used to pull the door panel 41. A fourth magnetic attraction piece 43 is fixedly connected to the upper part of the rear side of the door panel 41, and the fourth magnetic attraction piece 43 is magnetically connected to the third magnetic attraction piece 34. A fixing rod 44 is provided at the bottom of the door panel 41, and the fixing rod 44 is movably connected to the two second connecting holes 33. The fixing rod 44 is used for connecting the door panel 41 to the second storage box body 31. Two torsion springs 45 are sleeved outside the fixing rod 44, and the two torsion springs 45 are used for the automatic reset of the door panel 41 after it is unfolded.

[0047] Through the above solution: By providing a door closing structure 4 at the front part of the lower storage box 3, during the use of the device, the door closing structure 4 can be attached to the lower storage box 3 under the action of the magnetic attraction piece and the torsion spring 45 to prevent the door closing structure 4 from opening by itself. When the door closing structure 4 is opened to take the tools inside the lower storage box 3 and then the door closing structure 4 is released, the opening of the lower storage box 3 can be blocked by the elastic automatic reset of the torsion spring 45, improving the use safety of the device.

[0048] Furthermore, as shown in Figures 2-4 and Figure 10 、 Figure 11 the figure, the support frame 5 includes a first n-shaped frame 51. Two movable rings 52 are movably connected to the top of the first n-shaped frame 51, and both of the two movable rings 52 are fixedly connected to the front side of the bottom of the lower storage box 3. A second n-shaped frame 53 is movably connected inside the first n-shaped frame 51. The second n-shaped frame 53 and the first n-shaped frame 51 are unfolded into an X shape to support the lower storage box 3. Two arc-shaped clamping plates 54 are snap-connected to the outside of the second n-shaped frame 53 near the leg ends, and both of the two arc-shaped clamping plates 54 are fixedly connected to the rear side of the bottom of the lower storage box 3, and the two arc-shaped clamping plates 54 limit and block the top of the unfolded second n-shaped frame 53.

[0049] Through the above solution: By providing a support frame 5 at the bottom of the lower storage box 3, when the device is carried, the support frame 5 can be stored and will not occupy too much space. When the device is used, the support frame 5 is directly unfolded to support the device for use, improving the convenience during the use of the device.

[0050] Working principle: First, unfold the support frame 5 to support the device. Then, lift the drawing support plate 2 and pull the lower part of the drawing support plate 2 forward, so that the drawing support plate 2 can be limited and supported by two connecting support rods 14. Then, pull the extension plate 26 in the drawing support plate 2. When the extension plate 26 is pulled out of the box-shaped plate 21, it will bounce up through multiple rigid springs 27, making the surface of the extension plate 26 flush with the surface of the box-shaped plate 21. At the same time, due to the rigid characteristics of the rigid springs 27 themselves, it can prevent the extension plate 26 from sinking when the user uses the device for drawing. And the extension plate 26 bouncing through the rigid springs 27 also forms a limit between the extension plate 26 and the box-shaped plate 21, preventing the extension plate 26 from sliding into the box-shaped plate 21 by itself. Moreover, metal layers are provided on the surfaces of both the extension plate 26 and the box-shaped plate 21, and the drawing paper can be fixed on the support plate through magnetic buttons. Subsequently, pull the door closing structure 4 to take out the drawing tools stored in the lower storage box 3 for operation. When the tools are taken out, release the door closing structure 4, and the door closing structure 4 will automatically reset under the elastic force of the torsion spring 45 to prevent the drawing tools inside the lower storage box 3 from falling out.

[0051] The above shows and describes the basic principle, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A portable drawing device for environmental art design, comprising an upper storage box (1) and a drawing support plate (2) arranged on the upper part of the upper storage box (1), characterized in that: The bottom of the upper storage box (1) is fixedly connected to a lower storage box (3), the lower storage box (3) is used to store drawing tools, a sealing door structure (4) is arranged at the front of the lower storage box (3), the bottom of the lower storage box (3) is fixedly connected to a support frame (5) and two shoulder straps (6) distributed on the left and right, and the support frame (5) is located between the two shoulder straps (6); The upper storage box (1) comprises a first storage box body (11), the rear part of the left wall and the rear part of the right wall of the first storage box body (11) are both provided with strip-shaped slide grooves (12), and the two strip-shaped slide grooves (12) are both slidably connected with connecting pins (13), and the top rear side of the first storage box body (11) is provided with two connecting rods (14) distributed on the left and right, and the two connecting pins (13) and the two connecting rods (14) are both used to connect the drawing support board (2), and the front part of the lower wall of the first storage box body (11) is fixedly connected with two first magnetic suction sheets (15); The drawing support plate (2) comprises a box-shaped plate (21), and the box-shaped plate (21) is located inside the first storage box body (11). The box-shaped plate (21) is provided with a first connection hole (22) in the middle of the left side and the middle of the right side. The first connection hole (22) is used for movably connecting the connecting support rod (14). The box-shaped plate (21) is provided with an annular groove (23) at the rear of the left side and the rear of the right side. The annular groove (23) is used for connecting the connecting pin (13). Two second magnetic suction plates (25) are fixedly connected to the front side of the bottom of the box-shaped plate (21). The two second magnetic suction plates (25) are respectively magnetically connected to the two first magnetic suction plates (15).

2. A portable drawing device for environmental art design according to claim 1, characterized in that: The left and right inner walls of the box-shaped plate (21) are both provided with limited sliding grooves (24), and the box-shaped plate (21) is slidably connected with an extension plate (26), and the end surfaces of the extension plate (26) and the box-shaped plate (21) are both provided with metal plates for fixing the drawing paper via magnetic buckles.

3. A portable drawing device for environmental art design according to claim 2, characterized in that: The top of the extension plate (26) is provided with a plurality of grooves (261) distributed at equal distances, and the lower walls of the plurality of grooves (261) are fixedly connected with steel springs (27), and the tops of the plurality of steel springs (27) are fixedly connected with a sleeve (28), the sleeve (28) is slidably connected to the box-shaped plate (21), and the rear portions of the left side and right side of the sleeve (28) are fixedly connected with second sliders (29), and the two second sliders (29) are slidably connected with the two limiting slide grooves (24) respectively.

4. A portable drawing device for environmental art design according to claim 1, characterized in that: The connecting pin (13) comprises a fixed shaft (131), and both ends of the fixed shaft (131) are fixedly connected with first sliding blocks (132). The two first sliding blocks (132) are respectively located in the strip sliding groove (12) and the annular sliding groove (23), and are respectively slidably connected to the strip sliding groove (12) and the annular sliding groove (23).

5. A portable drawing device for environmental art design according to claim 1, characterized in that: The lower storage box (3) comprises a second storage box body (31), and the top of the second storage box body (31) is fixedly connected to the bottom of the first storage box body (11), a storage groove (32) is provided at the front opening of the second storage box body (31), and second connection holes (33) are provided at the lower part of the left wall and the lower part of the right wall in the storage groove (32), and a third magnetic attraction sheet (34) is fixedly connected to the upper part of the front side surface of the second storage box body (31).

6. A portable drawing device for environmental art design according to claim 5, characterized in that: The door sealing structure (4) comprises a door panel (41), and the door panel (41) is located inside the storage groove (32), a handle (42) is fixedly connected to the upper part of the front side of the door panel (41), and the handle (42) is used to pull the door panel (41), and a fourth magnetic attraction sheet (43) is fixedly connected to the upper part of the rear side of the door panel (41), and the fourth magnetic attraction sheet (43) is magnetically connected to the third magnetic attraction sheet (34).

7. A portable drawing device for environmental art design according to claim 6, characterized in that: A fixing rod (44) is provided at the bottom of the door panel (41), and the fixing rod (44) is movably connected to the two second connecting holes (33). The fixing rod (44) is used to connect the door panel (41) and the second storage box body (31). Two torsion springs (45) are sleeved on the outside of the fixing rod (44), and the two torsion springs (45) are used for automatic reset of the door panel (41) after it is unfolded.

8. The portable drawing device for environmental art design according to claim 1, characterized in that: The support frame (5) comprises a first n-shaped frame (51), the top of the first n-shaped frame (51) is movably connected to two movable rings (52), and the two movable rings (52) are fixedly connected to the bottom front side of the lower storage box (3), the first n-shaped frame (51) is movably connected to a second n-shaped frame (53) inside, and the second n-shaped frame (53) and the first n-shaped frame (51) are unfolded to form an X shape and support the lower storage box (3).

9. A portable drawing device for environmental art design according to claim 8, characterized in that: Two arc-shaped clamping plates (54) are snap-connected to the outside of the second n-shaped frame (53) near the end of the supporting legs, and the two arc-shaped clamping plates (54) are fixedly connected to the rear side of the bottom of the lower storage box (3), and the two arc-shaped clamping plates (54) limit and block the top of the unfolded second n-shaped frame (53).