Photovoltaic module packaging box

Abstract

This utility model relates to the field of packaging and transportation technology, and in particular to a photovoltaic module packaging box. The packaging box includes side panels, a bottom plate disposed at the bottom of the side panels, and a cover plate disposed at the top of the side panels. The side panels, bottom plate, and cover plate together form an inner cavity for accommodating the photovoltaic modules. At least one of the side panels, bottom plate, and cover plate includes a body layer and a drying layer disposed on the body layer, with a drying element disposed within the drying layer. This utility model provides a photovoltaic module packaging box to alleviate the technical problem of poor moisture-proof performance of existing photovoltaic module packaging boxes.

Description

Technical Field

[0001] This utility model relates to the field of packaging and transportation technology, and in particular to a photovoltaic module packaging box. Background Technology

[0002] A photovoltaic (PV) module is a device composed of multiple solar cells connected by electrical connections and mechanical encapsulation. It can independently output direct current (DC) and is commonly known as a photovoltaic panel or solar panel. PV modules are relatively large and are easily damaged by collisions with surrounding objects during transportation. Therefore, PV modules must be packaged in boxes before transport to protect them and reduce the possibility of damage.

[0003] Currently, corrugated cardboard boxes are generally used for packaging photovoltaic modules. However, corrugated cardboard boxes have poor moisture resistance. When the humidity is high, the compressive strength of corrugated paper will drop significantly, which increases the risk of PID effect in photovoltaic modules.

[0004] Therefore, this application provides a new photovoltaic module packaging box to address the above-mentioned problems. Utility Model Content

[0005] The purpose of this utility model is to provide a photovoltaic module packaging box to at least alleviate the technical problem of poor moisture-proof performance of photovoltaic module packaging boxes in the prior art.

[0006] To achieve the above objectives, this utility model provides a photovoltaic module packaging box, which includes a side panel, a bottom plate disposed at the bottom of the side panel, and a cover plate disposed at the top of the side panel. The side panel, the bottom plate, and the cover plate together form an inner cavity for accommodating the photovoltaic module. Among the three components—the side plate, the bottom plate, and the cover plate—at least one includes a body layer and a drying layer disposed on the body layer, wherein a drying element is disposed within the drying layer.

[0007] Furthermore, the drying component includes a desiccant package or a vacuum aluminum foil bag, wherein the desiccant package or the vacuum aluminum foil bag contains a desiccant.

[0008] Furthermore, the body layer is a first honeycomb paperboard; And / or, the drying layer is a second honeycomb paperboard, and the drying element is disposed within the interlayer of the second honeycomb paperboard.

[0009] Furthermore, a waterproof layer is provided on the side of the body layer away from the drying layer, and the waterproof layer is located away from the inner cavity.

[0010] Furthermore, the side panel includes two enclosure panels, each enclosure panel including a first plate and a second plate connected to each other, a first crease being provided between the first plate and the second plate, and the second plate being bendable relative to the first plate along the first crease; The two enclosure panels are connected so that the first and second panels of one enclosure panel are sequentially connected end to end with the first and second panels of the other enclosure panel to form the side panel.

[0011] Furthermore, the two enclosure panels are detachably connected, and / or the cover plate is detachably connected to the side panel, and the bottom plate is detachably connected to the side panel.

[0012] Furthermore, a first connecting plate is provided on the side of the second plate away from the first plate, and a second crease is provided between the second plate and the first connecting plate, and the first connecting plate can be bent relative to the second plate along the second crease; When two of the enclosure panels are connected, the first connecting plate of one enclosure panel is bent relative to the second plate and connected to the first plate of the other enclosure panel, and the first connecting plate and the first plate are detachably connected.

[0013] Furthermore, the first plate includes a first part and a second part connected to each other, the first part being connected to the second plate; wherein a third crease is provided between the first part and the second part, and the second part can be bent relative to the first part along the third crease.

[0014] Furthermore, along the length direction of the enclosure, the second part, the first part, and the second plate body all have the same length.

[0015] Furthermore, a reinforcing post is detachably provided at the corner of the base plate. When the side plate is connected to the base plate, the reinforcing post is provided on the side of the side plate near the inner cavity to support the side plate.

[0016] By adopting the above technical solution, the photovoltaic module packaging box of this utility model has at least the following beneficial effects: For example, the side plate includes a body layer and a drying layer disposed on the body layer; or the bottom plate includes a body layer and a drying layer disposed on the body layer; or the cover plate includes a body layer and a drying layer disposed on the body layer; or any two of the side plate, bottom plate, and cover plate include a body layer and a drying layer disposed on the body layer. Preferably, in this embodiment, all three of the side plate, bottom plate, and cover plate include a body layer and a drying layer disposed on the body layer.

[0017] With this design, the photovoltaic module packaging box of this embodiment places the photovoltaic modules inside the inner cavity during packaging and transportation, thus providing better protection for the photovoltaic modules during storage or transportation. The side panels, bottom plate, and cover plate comprise a main body layer and a drying layer disposed on the main body layer. Firstly, the drying layer contains a drying element that absorbs moisture from the packaging box, preventing corrosion of the photovoltaic modules by oxygen in the air and water, improving the moisture-proof performance of the photovoltaic module packaging, and extending the storage and transportation period of the photovoltaic modules. This makes the photovoltaic module packaging box of this embodiment particularly suitable for export sea freight of photovoltaic modules. Secondly, the drying element disposed inside the drying layer prevents damage to the outer surface of the photovoltaic modules caused by vibration. Thirdly, the side panels, bottom plate, and cover plate, comprising the main body layer and the drying layer disposed on the main body layer, create a double-layer structure for the packaging box. This results in high structural strength and stability, making it less prone to deformation and improving the protection of the photovoltaic modules inside the cavity. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of the photovoltaic module packaging box provided in an embodiment of the present utility model; Figure 2 A schematic diagram of the structure of the cover plate of the photovoltaic module packaging box provided in an embodiment of this utility model; Figure 3 A schematic diagram of the side panel of the photovoltaic module packaging box provided in an embodiment of this utility model; Figure 4 for Figure 3 A magnified view of a portion of the side panel structure shown; Figure 5 A schematic diagram of the structure of the enclosure panel of the photovoltaic module packaging box provided in an embodiment of this utility model; Figure 6 A schematic diagram of the structure of the bottom plate of the photovoltaic module packaging box provided in this embodiment of the utility model; Figure 7 for Figure 6 A magnified view of a portion of the base plate's structure; Figure 8 A cross-sectional structural diagram of the cover plate, side plate and bottom plate of the photovoltaic module packaging box provided for an embodiment of this utility model; Figure 9A schematic diagram of the side panel folding process of the photovoltaic module packaging box provided in this embodiment of the utility model.

[0020] Figure label: 1-Cover plate; 11-Hook and loop fastener; 2-Side panel; 21-Enclosure panel; 211-Hook and loop fastener; 212-Second part; 213-First part; 214-Second panel; 215-First connecting plate; 216-First panel; 31 - First crease; 32 - Second crease; 33 - Third crease; 4-Base plate; 5-Strengthening column; 61-Main body layer; 62-Drying layer; 63-Waterproof layer; 64-Drying component. Detailed Implementation

[0021] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0022] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0024] Example 1 Please see Figure 1 and combined Figure 8This embodiment provides a photovoltaic module packaging box, which includes a side plate 2, a bottom plate 4 disposed at the bottom of the side plate 2, and a cover plate 1 disposed at the top of the side plate 2. The side plate 2, the bottom plate 4, and the cover plate 1 together form an inner cavity for accommodating the photovoltaic module. Among the side plate 2, the bottom plate 4, and the cover plate 1, at least one includes a body layer 61 and a drying layer 62 disposed on the body layer 61. A drying element 64 is disposed in the drying layer 62.

[0025] Optionally, the side plate 2 includes a body layer 61 and a drying layer 62 disposed on the body layer 61; or the bottom plate 4 includes a body layer 61 and a drying layer 62 disposed on the body layer 61; or the cover plate 1 includes a body layer 61 and a drying layer 62 disposed on the body layer 61; or any two of the side plate 2, bottom plate 4, and cover plate 1 include a body layer 61 and a drying layer 62 disposed on the body layer 61. Preferably, in this embodiment, the side plate 2, bottom plate 4, and cover plate 1 all include a body layer 61 and a drying layer 62 disposed on the body layer 61.

[0026] It should be noted that the packaging box in this embodiment can be used to package fragile photovoltaic modules such as double-glass modules and flexible modules, and is especially suitable for long-distance transportation and storage of photovoltaic modules.

[0027] With this design, the photovoltaic module packaging box of this embodiment places the photovoltaic modules inside the inner cavity during packaging and transportation, thus providing better protection for the photovoltaic modules during storage or transportation. The side plate 2, bottom plate 4, and cover plate 1 together include a body layer 61 and a drying layer 62 disposed on the body layer 61. Firstly, the drying layer 62 contains a drying element 64, which absorbs moisture inside the packaging box, preventing oxygen in the air and water from corroding the photovoltaic modules, improving the moisture-proof performance of the photovoltaic module packaging, and extending the storage and transportation period of the photovoltaic modules. This makes the packaging box of this embodiment particularly suitable for export sea freight of photovoltaic modules. Secondly, the drying element 64, disposed inside the drying layer 62, can prevent damage to the outer surface of the photovoltaic modules caused by vibration. Thirdly, the combination of the side plate 2, bottom plate 4, and cover plate 1, including the body layer 61 and the drying layer 62 disposed on the body layer 61, results in a double-layer structure for the packaging box. This structure provides high structural strength and stability, making it less prone to deformation and improving the protection of the photovoltaic modules inside the cavity.

[0028] Optionally, the drying layer 62 can be disposed on the side of the body layer 61 near the inner cavity, or the drying layer 62 can be disposed on the side of the body layer 61 away from the inner cavity.

[0029] Optionally, the drying element 64 includes a vacuum aluminum foil bag or a desiccant pack containing a desiccant, which may be a combination of montmorillonite (moisture absorption rate ≥20%) and cobalt chloride indicator.

[0030] Optionally, the body layer 61 is a first honeycomb paperboard, or the drying layer 62 is a second honeycomb paperboard, and the drying element 64 is disposed within the interlayer of the second honeycomb paperboard. Preferably, in this embodiment, please refer to... Figure 8 The body layer 61 is a first honeycomb paperboard, and the drying layer 62 is a second honeycomb paperboard. The drying element 64 is disposed in the interlayer of the second honeycomb paperboard.

[0031] In other words, the side panel 2, bottom panel 4, and cover panel 1 are all constructed with double-layer honeycomb paperboard. Firstly, honeycomb paperboard is relatively inexpensive, reducing the cost of the packaging box. In addition, honeycomb paperboard is biodegradable and pollution-free, conforming to modern environmental protection trends. Secondly, honeycomb paperboard has good toughness and resilience, providing excellent cushioning performance and effectively protecting the photovoltaic modules inside the cavity. Thirdly, the packaging box with a double-layer honeycomb paperboard structure has high structural strength and stability, is not easily deformed, and has outstanding compression and bending resistance, further enhancing the protection of the photovoltaic modules inside the cavity.

[0032] The drying element 64 is disposed in the interlayer of the second honeycomb paperboard, which can prevent the drying element 64 from being damaged by friction on the outer surface of the photovoltaic module due to vibration.

[0033] Optionally, the parameters of the first and second honeycomb paperboards can be as follows: the internal honeycomb structure is a hexagonal structure with a pore size of Φ10mm, the compressive strength is 180kPa (GB / T 22874), the width of the pre-shear stress relief groove is 2mm, the spacing is 50mm, and the energy absorption rate is 65% after drop hammer test.

[0034] Preferably, please refer to Figure 8 Multiple drying elements 64 are provided, and the multiple drying elements 64 are spaced apart along the extension direction of the second honeycomb cardboard. This arrangement further improves the moisture-proof performance of the packaging box and alleviates the technical problem of poor moisture-proof performance of photovoltaic module packaging boxes in the prior art.

[0035] Preferably, please refer to Figure 8 In this embodiment, a waterproof layer 63 is provided on the side of the body layer 61 away from the drying layer 62, and the waterproof layer 63 is located away from the inner cavity.

[0036] For example, the waterproof layer 63 is made of hydrophobic nano-silica. The addition of the waterproof layer 63 further improves the waterproof performance of the packaging box, ensuring the safe packaging and transportation of photovoltaic modules.

[0037] Preferably, please refer to Figure 3 and Figure 5 In this embodiment, the side panel 2 includes two surrounding panels 21. The surrounding panel 21 includes a first plate 216 and a second plate 214 connected together. A first crease 31 is provided between the first plate 216 and the second plate 214. The second plate 214 can be bent relative to the first plate 216 along the first crease 31. The two surrounding panels 21 are connected so that the first plate 216 and the second plate 214 of one surrounding panel 21 are sequentially connected end to end with the first plate 216 and the second plate 214 of the other surrounding panel 21 to form the side panel 2.

[0038] With this configuration, when assembling the packaging box, the two side panels 21 are connected so that the first panel 216 and the second panel 214 of one side panel 21 are sequentially connected end to end to form the side panel 2. Then, the cover plate 1 is fastened to the top of the side panel 2, and the bottom plate 4 is connected to the bottom of the side panel 2. Assembly is simple and convenient. When packaging and transporting photovoltaic modules, the photovoltaic modules are placed in the inner cavity, thus the packaging box can provide good protection for the photovoltaic modules during storage or transportation.

[0039] When the packaging box needs to be folded, the cover plate 1 and the bottom plate 4 are removed from the side plate 2. Then, the two side panels 21 are disassembled. The second plate 214 of the two side panels 21 is bent along the first crease 31 towards the first plate 216. The bending is completed when the second plate 214 contacts the first plate 216. The folded side panels 21 are stacked, and then the cover plate 1 and the bottom plate 4 are stacked together to complete the folding of the packaging box. This reduces the volume of the packaging box, facilitates the recycling, transportation and storage of the packaging box, and reduces the logistics and storage costs of the packaging box.

[0040] Optionally, the two enclosure panels 21 are detachably connected, or the cover plate 1 and the side plate 2 are detachably connected, and the bottom plate 4 and the side plate 2 are detachably connected. Preferably, in this embodiment, the two enclosure panels 21 are detachably connected, the cover plate 1 and the side plate 2 are detachably connected, and the bottom plate 4 and the side plate 2 are detachably connected.

[0041] Optionally, the two enclosure panels 21, the cover plate 1 and the side panel 2, and the bottom plate 4 and the side panel 2 can be detachably connected by hinges or by Velcro. Preferably, in this embodiment, the two side panels 21 are detachably connected by Velcro, the cover plate 1 and the side panel 2 are detachably connected by Velcro, and the bottom plate 4 and the side panel 2 are detachably connected by Velcro. The following description uses the cover plate 1 and the side panel 2 as an example; please refer to [link to documentation]. Figure 2 and Figure 5The cover plate 1 is provided with a Velcro tab 11, and the side panel 2 is provided with a Velcro tab 211.

[0042] This design facilitates the disassembly and connection of the two side panels 21, the cover 1 and the side panel 2, and the bottom panel 4 and the side panel 2, thereby facilitating the assembly and folding of the packaging box.

[0043] Specifically, when folding the packaging box, the Velcro between the cover plate 1 and the side plate 2, as well as the Velcro between the bottom plate 4 and the side plate 2, are unlocked to remove the cover plate 1 and the bottom plate 4 from the side plate 2. Then, the Velcro between the two side panels 21 is unlocked, and the two side panels 21 are separated. The second plate 214 of the two side panels 21 is then bent along the first crease 31 towards the first plate 216 until the second plate 214 contacts the first plate 216, thus completing the folding of the side panels 21. The two folded side panels 21 are then stacked, and the cover plate 1 and the bottom plate 4 are stacked together to complete the folding of the packaging box. This reduces the volume of the packaging box, making it easier to recycle, transport, and store, and reducing the logistics and storage costs of the packaging box.

[0044] Preferably, please refer to Figure 4 and Figure 5 In this embodiment, a first connecting plate 215 is provided on the side of the second plate 214 away from the first plate 216, and a second crease 32 is provided between the second plate 214 and the first connecting plate 215. The first connecting plate 215 can be bent relative to the second plate 214 along the second crease 32. When the two surrounding plates 21 are connected, the first connecting plate 215 of one surrounding plate 21 is bent relative to the second plate 214 and connected to the first plate 216 of the other surrounding plate 21. The first connecting plate 215 and the first plate 216 are detachably connected.

[0045] For example, the first connecting plate 215 of one panel 21 can be detachably connected to the first plate 216 of another panel 21 by means of Velcro or hinge.

[0046] The first connecting plate 215 facilitates the connection between the two side panels 21, and the detachable connection between the two side panels 21 makes it easy to disassemble the two side panels 21 when folding the packaging box, thus improving the convenience and efficiency of folding the packaging box.

[0047] Preferably, please refer to Figure 9 In this embodiment, the first plate 216 includes a first part 213 and a second part 212 connected to each other, and the first part 213 is connected to the second plate 214; wherein, a third crease 33 is provided between the first part 213 and the second part 212, and the second part 212 can be bent relative to the first part 213 along the third crease 33.

[0048] It should be noted that the processing methods of the first crease 31, the second crease 32 and the third crease 33 are existing technologies, such as processing by pre-compression micro-crack process. Optionally, the crease depth of the first crease 31, the second crease 32 and the third crease 33 is 0.3 mm and the folding torque is 0.45 N·m.

[0049] For this setting, please refer to [link / reference]. Figure 9 When folding the packaging box, the second part 212 is bent along the third crease 33 towards the first part 213 until the second part 212 contacts the first part 213, completing the first fold of the enclosure 21; then the second plate 214 is bent along the first crease 31 towards the first plate 216 until the second plate 214 contacts the second part 212, completing the second fold of the enclosure 21. Thus, the folding of the packaging box enclosure 21 is completed, further reducing the folded volume. At this time, the folded enclosure 21 includes the second plate 214, the second part 212 and the first part 213 stacked sequentially along the folding direction.

[0050] Preferably, please refer to Figure 9 In this embodiment, the second part 212, the first part 213 and the second plate 214 are all the same length along the length direction of the enclosure 21.

[0051] With this configuration, the folded panel 21 includes a second panel 214, a second part 212, and a first part 213 stacked sequentially along the folding direction. Since the three parts are of the same length, the length of the folded panel 21 is reduced, thereby improving the packaging efficiency of the packaging box.

[0052] Preferably, please refer to Figure 6 and Figure 7 In this embodiment, a reinforcing column 5 is detachably provided at the corner of the base plate 4. When the side plate 2 is connected to the base plate 4, the reinforcing column 5 is provided on the side of the side plate 2 near the inner cavity to support the side plate 2.

[0053] Optionally, the reinforcing column 5 has dimensions of 20 mm × 20 mm × 50 mm, a static load capacity of ≥800 kg, and is detachable and reusable.

[0054] Among them, the reinforcement of column 5 prevents the photovoltaic modules inside the cavity from being squeezed in case of damage to the packaging box, thus improving the protection effect of the photovoltaic modules.

[0055] In summary, the packaging box of this embodiment offers several advantages. First, its folding performance is improved: the return freight cost for empty boxes is reduced from ¥2.3 / box / km to ¥0.7 / box / km (a saving of 69.6%); and the warehouse floor space is reduced by 75%. Second, its moisture-proof performance is verified; the high humidity test (85℃ / 85%RH, 1000h) results show that the PID degradation rate of photovoltaic modules is <2% (industry standard <5%). Third, its mechanical strength is guaranteed; the vibration test (ISTA 3A) results show that the photovoltaic module breakage rate is reduced from 1.2% to 0.3%; and the stacking test results show that the deformation is <2mm under a load of 800kg.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A photovoltaic module packaging box, characterized in that, It includes a side plate (2), a bottom plate (4) disposed at the bottom end of the side plate (2) and a cover plate (1) disposed at the top end of the side plate (2). The side plate (2), the bottom plate (4) and the cover plate (1) together form an inner cavity for accommodating photovoltaic modules. Among them, at least one of the side plate (2), the bottom plate (4) and the cover plate (1) includes a body layer (61) and a drying layer (62) disposed on the body layer (61), and a drying element (64) is disposed in the drying layer (62).

2. The photovoltaic module packaging box according to claim 1, characterized in that, The drying component (64) includes a desiccant pack or a vacuum aluminum foil bag, wherein the desiccant pack or the vacuum aluminum foil bag contains a desiccant.

3. The photovoltaic module packaging box according to claim 1, characterized in that, The body layer (61) is a first honeycomb paperboard; And / or, the drying layer (62) is a second honeycomb paperboard, and the drying element (64) is disposed in the interlayer of the second honeycomb paperboard.

4. The photovoltaic module packaging box according to claim 1, characterized in that, A waterproof layer (63) is provided on the side of the body layer (61) away from the drying layer (62), and the waterproof layer (63) is located away from the inner cavity.

5. The photovoltaic module packaging box according to any one of claims 1-4, characterized in that, The side panel (2) includes two enclosure panels (21), each enclosure panel (21) including a first plate (216) and a second plate (214) connected together. A first crease (31) is provided between the first plate (216) and the second plate (214), and the second plate (214) can be bent relative to the first plate (216) along the first crease (31). The two enclosure panels (21) are connected so that the first plate (216) and the second plate (214) of one enclosure panel (21) are connected end to end with the first plate (216) and the second plate (214) of the other enclosure panel (21) to form the side panel (2).

6. The photovoltaic module packaging box according to claim 5, characterized in that, The two enclosure panels (21) are detachably connected, and / or the cover plate (1) is detachably connected to the side plate (2), and the bottom plate (4) is detachably connected to the side plate (2).

7. The photovoltaic module packaging box according to claim 5, characterized in that, A first connecting plate (215) is provided on the side of the second plate (214) away from the first plate (216). A second crease (32) is provided between the second plate (214) and the first connecting plate (215). The first connecting plate (215) can be bent relative to the second plate (214) along the second crease (32). When two enclosures (21) are connected, the first connecting plate (215) of one enclosure (21) bends relative to the second plate (214) and connects with the first plate (216) of the other enclosure (21), and the first connecting plate (215) and the first plate (216) are detachably connected.

8. The photovoltaic module packaging box according to claim 5, characterized in that, The first plate (216) includes a first part (213) and a second part (212) connected to each other, the first part (213) and the second plate (214) are connected; wherein, a third crease (33) is provided between the first part (213) and the second part (212), and the second part (212) can be bent relative to the first part (213) along the third crease (33).

9. The photovoltaic module packaging box according to claim 8, characterized in that, Along the length of the enclosure (21), the second part (212), the first part (213), and the second plate (214) are all the same length.

10. The photovoltaic module packaging box according to any one of claims 1-4, characterized in that, A reinforcing column (5) is detachably provided at the corner of the base plate (4). When the side plate (2) is connected to the base plate (4), the reinforcing column (5) is provided on the side of the side plate (2) near the inner cavity to support the side plate (2).

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