Rapidly-formed integrated double-layer paperboard support, paperboard structure and paper support

Abstract

According to the rapid-forming integrated double-layer paperboard structure and the rapid-forming integrated double-layer paperboard support, rapid unfolding and stable supporting of the double-layer structure are achieved through the exquisite design of the integrated-forming paperboard. The product is characterized by comprising a double-layer paperboard main body formed by folding and bonding the middle part, and an upper-layer base plate and a lower-layer base plate which are arranged in a partitioned manner are provided with pre-pressing creases to fix the thickness and facilitate folding; the storage groove is provided with a supporting tongue and an inserting groove system, and supporting strips and clamping grooves at specific positions are designed, so that multi-direction stable supporting after the commodities are placed in is ensured. The innovation point is that a flat state can be quickly converted into a double-layer structure by utilizing a simple extrusion action, meanwhile, the flexibility of the storage groove and the supporting system adapts to diversified packaging requirements, stability, convenience and customized adaptation capability are considered, the packaging box lining is particularly suitable for being used as various packaging box liners, the transportation and storage cost and the packaging efficiency are optimized, and the market prospect is wide. And an efficient and environment-friendly packaging solution is shown.

Description

Technical Field

[0001] The utility model relates to the field of packaging paper products, mainly to the technology of paperboard inner tray products, and specifically to a rapidly formed integrated double-layer paperboard tray, a paperboard structure and a paper tray. Background Art

[0002] As a crucial component of product distribution, product packaging serves a purpose far beyond simple packaging and protection. It also carries the weight of brand identification, attracting consumer attention, and enhancing the overall value of a product. However, while striving for both aesthetics and practicality, the selection of traditional packaging materials faces a series of challenges, particularly in terms of environmental performance, logistics efficiency, and warehousing economics. While traditional cardboard packaging materials, such as plastics (e.g., EPS (polystyrene foam), pearl cotton, sponge, and foam, offer excellent protection, their environmental impact cannot be ignored. These materials are often non-biodegradable, and improper handling can easily lead to land and water pollution, resulting in long-term impacts on ecosystems. With the global emphasis on sustainable development, consumers and businesses are increasingly opting for environmentally friendly and recyclable packaging solutions. On the other hand, these traditional packaging materials often present challenges in terms of size and transportation costs. These materials are often bulky and lightweight, which means they take up more space during transportation, increasing shipping costs. This low space utilization directly translates into higher logistics costs, particularly for merchants packaging goods. From the perspective of warehousing and operational efficiency, these traditional tray materials are large in size and take up a lot of warehouse space, which is not conducive to inventory cost management.

[0003] To address these challenges, a range of innovative, environmentally friendly inner tray solutions are being increasingly adopted: Paper inner trays: Made from high-strength corrugated or honeycomb cardboard, these inner trays not only offer excellent cushioning properties but are also fully recyclable, minimizing environmental impact. Their flat design facilitates transport and storage, significantly improving space utilization. However, traditional paper inner trays also present challenges. For example, when creating a double-layer inner lining, ensuring the integrity of the paperboard requires complex folding, which complicates the cutting process. The folding process involves multiple, time-consuming steps and often requires manual placement and adjustment, which is not only labor-intensive but also reduces overall packaging efficiency. Alternatively, when stacking two inner trays, each needs to be folded and aligned, a tedious and time-consuming process. This inefficiency can become a bottleneck in companies' ability to quickly respond to market demand, especially during periods of surging order volumes, such as the Mid-Autumn Festival and Singles' Day shopping festivals. Utility Model Content

[0004] To address the deficiencies and defects of the above-mentioned prior art, the inventors have developed and designed a quick-to-produce integrated double-layer cardboard tray, cardboard structure, and paper tray, aiming to provide a stable, flexible, and efficient packaging solution. It is particularly suitable for use as an inner lining for various packaging boxes, and can maintain the thin cardboard shape during transportation and warehousing. During use, it can be quickly formed into a double-layer integrated double-layer inner tray with storage slots. There is no need for complex folding and forming, and no need for double-layer split stacking. Goods can be directly placed in the tray for packaging. It is fast, efficient, easy to use, stable, environmentally friendly, and lightweight, which can effectively save transportation and storage costs and improve packaging efficiency. Specifically, the working principle of the utility model is as follows:

[0005] Integrated molding and dual-layer structure: This product is made by folding and bonding a single piece of cardboard along a specific design, creating a dual-layer structure with an upper and lower base when squeezed inward from both sides. This design cleverly utilizes multiple creases and slots to quickly form a dual-layer base. The support structure of the base ensures its strength and stability, creating a support space that is both lightweight and stable.

[0006] Storage slots and support system: Storage slots are provided on the upper and lower panels for directly placing items, and each slot is equipped with support tongues on the edge. These tongues can be folded down after the items are placed and fixed through slots to form direct support for the bottom of the items. Some storage slots also have built-in support bars that can stand upright and insert into the upper slots when the structure is unfolded, further enhancing the stability between the upper and lower layers. The support design of the support tongues enables the goods to be placed horizontally and vertically in a variety of usage forms, which can meet the needs of various packaging boxes. It has good practicality and scalability, and the shape design of the storage slots can be modified according to the product form. Whether it is the quantity, shape, depth, specifications, etc., the adaptive design can be adjusted, which has better practicality and applicability.

[0007] Pre-stressed creases and adaptive design: The cardboard is pre-stressed with creases, which guide precise folding and define the thickness of the upper and lower bases. These creases ensure the rapid forming and stability of the structure, while also facilitating the adjustment of the inner support space according to the size of the item, improving adaptability and flexibility. Furthermore, these creases can be provided with a number of strip holes, where the corresponding strip holes can be used as slots for support strips, forming a connection and support between the upper and lower bases, thereby maintaining stability and firmness between the upper and lower bases. At the same time, these crease designs can also provide corresponding auxiliary guidance during extrusion molding, enabling one-time molding. By applying pressure on both sides of the cardboard, the upper and lower bases can quickly expand from a flat state to a predetermined thickness, forming a stable double-layer structure. The design of the supporting tongue and slot allows the supporting tongue to be squeezed inward and stuck in the slot to form a limited fixation when the product is placed, thereby forming a supporting surface. When the supporting surface is used as the bottom of the product, it can remain placed vertically, and is suitable for vertically placed beverage products and vertically lifted packaging boxes. The height, shape (such as a trapezoidal surface with ridges) and position layout of the supporting tongue and support bar have been carefully designed to ensure that they are precisely matched with the thickness of the upper and lower bases, while providing sufficient supporting force without affecting the flatness and aesthetics of the overall structure. It can also be applied to various shapes of different specifications, thicknesses, sizes and lengths. The supporting tongue can also provide a wrapping and pressing clamping around the product to further ensure the stability and firmness of the product after placement.

[0008] Compared with the prior art, the present invention has the following beneficial technical effects:

[0009] (1) Efficient forming: This utility model changes the traditional manual multiple folding box, improves assembly efficiency and the appearance of the assembled display; a stable double-layer structure inner tray can be quickly formed from a single piece of cardboard through a simple inward squeezing operation, without the need for complex assembly, which greatly improves packaging efficiency. Compared with the traditional paper inner tray that requires multiple folding and forming processes, the cardboard inner tray of this utility model can quickly form a double-layer storage slot inner tray, which is efficient and convenient; users can easily operate it without any learning costs, the forming process is simple and fast, which improves the operating efficiency and is suitable for large-scale production and application; and there is no need to stack them separately, the double-layer inner tray can be directly formed and can be placed immediately after use, which simplifies the packaging process, reduces the risk of incorrect assembly, and improves logistics efficiency.

[0010] (2) Cost savings: The inner tray design of the present invention changes the traditional logistics stacking space and reduces transportation costs by 90%. This inner tray is easy to transport; because the cardboard inner tray is in a double-layered storage state before extrusion molding, this state is the thickness of two layers of cardboard. Compared with traditional inner trays such as foam and pearl cotton, it does not occupy the space in the car compartment and warehouse, which greatly reduces logistics costs. That is, it increases the loading capacity and reduces the space requirements during transportation and storage. There is also no large storage requirement, which reduces the transportation and storage costs.

[0011] (3) The product has excellent load-bearing capacity and stability: The structural design of the support tongue, slot and support bar in the utility model provides multi-point support for the placed items, which not only enhances the load-bearing capacity, but also ensures the stability of the goods during transportation, reduces the risk of damage, and meets various display methods, whether it is placed horizontally or vertically. It can be used for horizontal packaging boxes and vertical packaging boxes, and is suitable for use in various types of packaging box linings, expanding the scope of application; through the clever crease and slot design, the high-strength application of lightweight materials is achieved, and the innovative design of the support system ensures that good structural stability can be maintained even under thin material conditions; it can provide stable support, has no deformation, good molding quality, and stable, safe and reliable storage of goods.

[0012] (4) Flexibility and safety: The shape, number, and depth of the storage slots can be customized as needed. Combined with pre-pressed creases, they can accommodate products of different sizes and shapes, improving the versatility and customization of the packaging. Made of paper, it is recyclable, in line with environmental trends and reducing environmental impact. It also has a unique design aesthetic, facilitating subsequent printing and pattern design, enriching the aesthetics. The openable double-layer design makes it very suitable for use with products such as fruit, beverages, milk, and health products, improving the packaging quality while enhancing the fun of double-layer placement. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the structure of the integrated double-layer paperboard paper tray body;

[0014] Figure 2 Schematic diagram of the cardboard folding process for the integrated double-layer cardboard tray;

[0015] Figure 3 This is a schematic diagram of the cardboard folding process of the integrated double-layer cardboard tray;

[0016] Figure 4 This is a three-dimensional diagram of the molding structure of the integrated double-layer cardboard tray;

[0017] Figure 5 This is a schematic diagram of the integrated double-layer cardboard tray in use;

[0018] Figure 6 This is a schematic diagram of the packing process of the integrated double-layer cardboard tray;

[0019] Figure 7 A diagram of the cardboard structure supporting the second adhesive portion according to the preferred design of Example 2;

[0020] Figure 8 Schematic diagram of the extrusion molding process of the inner support paperboard under the preferred design in Example 2;

[0021] Figure 9 This is a schematic diagram of a cardboard structure with a special-shaped storage slot;

[0022] Figure 10 This is a schematic diagram of the usage of a cardboard inner tray with a special-shaped storage slot;

[0023] Among them: 100—inner cardboard body, 10—upper base, 11—first upper panel, 12—first lower panel, 20—lower base, 21—second upper panel, 22—second lower panel, 30—storage slot, 31—support tongue, 32—support strip, 41—slot, 42—card slot, 50—pre-pressed fold, 51—first fold, 52—second fold, 53—third fold, 54—fourth fold, 55—thickness surface, 56—adhesive ear, 57—second adhesive portion. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. Furthermore, descriptions of known structures and technologies are omitted in the following description to avoid unnecessary confusion regarding the concepts of the present invention.

[0025] Example 1: A rapid prototyping integrated double-layer cardboard tray, comprising:

[0026] The inner support cardboard body 100 is made of an integrally formed cardboard, which is folded and bonded at both ends in the middle to form a double-layer cardboard; the middle refers to the central horizontal line in the length direction of the cardboard, and the bonding portion is the midline area; the left and right double-layer bases are divided into two left and right cardboard intervals with the bonding portion as the midline, one of which is the upper base 10, and the interval on the other side is the lower base 20. The upper base 10 includes a first upper panel 11 and a first lower panel 12, and the lower base 20 includes a second upper panel 21 and a second lower panel 22; that is, after one side is folded, it can form the upper base 10, and after the other side is folded, it constitutes the lower base 20. The base described in this embodiment includes a two-layer cardboard structure, namely an upper panel and a lower panel, and the thickness of the base is formed by the spacing between them. Of course, the base also includes two A side panel is formed by folding the inner paperboard main body 100; on the upper panel, a slot for storing items 30 is pre-cut, that is, the storing items 30 are arranged in a single row or multiple rows on the first upper panel 11 and the second upper panel 21; it is used for the packaging box to serve as a slot for placing and accommodating goods; when the storing slot 30 is opened, at least one supporting tongue 31 is reserved, and a corresponding slot 41 is opened on the other corresponding panel, so that the supporting tongue 31 can be inserted into the corresponding slot 41 to form a supporting surface; the storing slot 30 located on the long side of the second upper panel 21 is also reserved with a support bar 32, and a card slot 42 is opened at a corresponding position on the first lower panel 12, and the support bar 32 can be inserted into the card slot 42 to form support between the upper and lower layers. In actual use, after the product is placed in the storage slot 30, the support tongue 31 can be squeezed and folded inward, and directly pushed into the slot 41 to form a support surface perpendicular to the placement surface, which can provide a support for the product. When lifting it vertically, the support surface also supports the bottom of the product to prevent it from collapsing or shifting in the storage slot 30. The support bar 32 acts as a support column, supporting the upper base 10 and the lower base 20 to limit the position and connect them, making the two more stable after being connected.

[0027] Preferably, a pre-stressed fold 50 is provided along the length direction between the first upper panel 11 and the first lower panel 12, and between the second upper panel 21 and the second lower panel 22, and the spacing between the pre-stressed folds 50 is used as the thickness of the upper base 10 or the lower base 20; the two long sides of the bonding portion are also provided with pre-stressed folds 50, and the spacing between the long sides of the bonding portion and the pre-stressed fold 50 is adapted to the thickness of the upper base 10 or the lower base 20; the card slot 42 is provided on the pre-stressed fold 50; the pre-stressed fold 50 can assist in the rapid molding of the inner support, that is, it serves as a molding guide between the upper panel, the lower panel, and the side panels, and is also a structural line, which is necessary in the extrusion molding process and can guide each panel to quickly unfold to form a bracket structure. In actual use, when extruded inward from the left and right cardboard intervals, the upper base 10 and the lower base 20 can quickly expand their thickness and form a double-layer structure of upper and lower layers. This design does not require partial folding, slot 41 operation, flanging operation, etc. It only needs to be squeezed inward to quickly unfold to form a double-layer bracket-type lining structure, which supports the rapid placement of double-layer goods. The height of the support tongue 31 does not exceed the spacing between the pre-pressed folds 50; the end of the support bar 32 is designed to be a trapezoidal surface with ridges. After being inserted into the corresponding card slot 42, the ridges can be stuck in the card slot 42; the height of the trapezoidal surface is adapted to the thickness of the upper base 10. The ridges play a limiting role after being inserted into the card slot 42, preventing it from easily falling out of the card slot 42. In this embodiment, the support tongues 31 can be three or four, and are arranged along the four sides of the storage slot 30; the storage slot 30 is square, rectangular or irregular in shape, and its spacing, depth, and shape are adapted to the size and shape of the goods to be placed.

[0028] Example 2: A rapidly formed integrated double-layer paperboard support cardboard structure, comprising:

[0029] The inner support paperboard has a rectangular strip structure, with two first folds 51 provided in the middle part, the bonding area is placed on the midline area of the middle part, and along the middle part to the two ends, the second folds 52, the third folds 53, and the fourth folds 54 are respectively formed to form the first lower panel 12 of the upper base 10 and the second upper panel 21 of the lower base 20, the thickness surface 55 of the upper base 10 and the lower base 20, the first upper panel 11 of the upper base 10 and the second lower panel 22 of the lower base 20, and the bonding ear 56 of the upper base 10 and the lower base 20; the middle part is formed between the two first folds 51, that is, when the formed paper support is placed vertically or flat on its side; between the first fold 51 and the second fold 52 The first upper panel 11 of the upper base 10 and the second lower panel 22 of the lower base 20 are formed, the side panels of the upper base 10 and the lower base 20 are formed between the second fold 52 and the third fold 53, and the second lower panel 22 of the upper base 10 and the second upper panel 21 of the lower base 20 are formed between the third fold 53 and the fourth fold 54; it should be noted that the bonding ear 56 is bonded to the midline area of the middle part, forming the spacing cavity thickness between the upper base 10 and the lower base 20, and the bonding ear 56 can be designed to be mutually staggered and side by side. The width of the bonding ear 56 determines the spacing height between the upper and lower bases 20, which needs to be designed according to the height after the product is actually placed.

[0030] Several storage slots 30 are provided on the first upper panel 11 of the upper base 10 and the second upper panel 21 of the lower base 20. A downwardly foldable support tongue 31 is provided on at least one side of the storage slots 30. The storage slots 30 on the second upper panel 21 may also include support bars 32 that stand upright after folding. Slots 41 corresponding in position, number, and size to the folds of the support tongues 31 are provided on the first lower panel 12 of the upper base 10 and the second lower panel 22 of the lower base 20. When merchandise is placed in the storage slots 30, the folded support tongues 31 are pressed downward, allowing their ends to be inserted into the slots 41 to form a support surface. When the goods are placed, the support tongue 31 can be squeezed to move inward and snap into the slot 41 to form a limited fixation, thereby forming a support surface, and when the support surface is used as the bottom of the goods, it can be kept vertically placed, which is suitable for vertically placed beverage goods and vertically lifted packaging boxes; the height, shape of the support tongue 31 and the support bar 32, such as the trapezoidal surface with ridges, and the position layout are all carefully designed to ensure that they are accurately matched with the thickness of the upper and lower bases 20, while providing sufficient supporting force without affecting the flatness and aesthetics of the overall structure; and can be applied to various shapes of different specifications, thicknesses, sizes and lengths; and the support tongue 31 can also provide a wrapping and pressing clamping around the goods, further ensuring the stability and firmness of the goods after placement.

[0031] Preferably, the edge of the storage slot 30 near the edge of the second upper panel 21 of the lower base 20 is aligned with the third fold 53, and a support bar 32 is provided. When the third fold 53 is folded, the support bar 32 is in an upwardly upright position and can be inserted into the slot 42 defined in the third fold 53 of the upper base 10, thereby forming a support between the upper base 10 and the lower base 20. The length of the support bar 32 is slightly longer, and its length needs to be precisely calculated to match the interlayer spacing between the upper base 10 and the lower base 20. This allows the support bar 32 to serve as a support column between the upper and lower layers, forming a parallel planar space between the upper and lower layers and providing support and molding. That is, the length of the support bar 32 is set so that, after insertion into the slot 42, its end face can bear against the inner top surface of the upper base 10, maintaining the upper base 10 and the lower base 20 parallel to each other. The support tongues 31 are located on at least one vertical edge of the storage slot 30. This vertical edge is the side where the bottom surface of the cardboard inner tray lies when the product is placed. Auxiliary support tongues 31 are also located on the other edges. The height of the auxiliary support tongues 31 does not exceed the thickness of the base tray on which they are located. The auxiliary support tongues 31 provide a lateral wrapping and clamping effect on the product after it is inserted into the storage slot 30, further improving the product's stability and providing support for the base tray frame.

[0032] In a preferred embodiment, the end of the supporting tongue 31 is provided with a second adhesive portion 57, and the height of the supporting tongue 31 is adapted to the thickness of the base in the layer in which it is located, and the second adhesive portion 57 is adhered to the corresponding first lower panel 12 and second lower panel 22; so that when squeezed inward from the left and right cardboard intervals, the upper base 10 and the lower base 20 can quickly expand their thickness and form a double-layer structure of the upper and lower layers, and the supporting tongue 31 can be synchronously stretched and folded to form a supporting surface in the storage slot 30.

[0033] It should be understood that the above-described specific embodiments of the present invention are merely illustrative of or explanation of the principles of the present invention and do not constitute limitations of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the scope of protection of the present invention. In addition, the appended claims of the present invention are intended to cover all variations and modifications that fall within the scope and metes and bounds of the appended claims, or equivalents thereof.

Claims

1. A rapid prototyping integrated double-layer cardboard tray, characterized in that include: The inner supporting paperboard body (100) is formed by folding two ends of an integrally formed paperboard and bonding them in the middle to form a double-layer paperboard; The left and right double-layer bases are divided into two left and right cardboard sections with the bonding portion as the center line, one section being the upper base (10) and the other section being the lower base (20), the upper base (10) comprising a first upper panel (11) and a first lower panel (12), and the lower base (20) comprising a second upper panel (21) and a second lower panel (22); The storage slots (30) are arranged in a single row or multiple rows on the first upper panel (11) and the second upper panel (21); When the object groove (30) is opened, at least one supporting tongue (31) is reserved, and a corresponding slot (41) is opened on the corresponding other panel, so that the supporting tongue (31) can be inserted into the corresponding slot (41) to form a supporting surface; A support strip (32) is also reserved in the storage slot (30) located on one side of the long side of the second upper panel (21), and a card slot (42) is opened at a corresponding position on the first lower panel (12), and the support strip (32) can be inserted into the card slot (42) to form support between the upper and lower layers.

2. The integrated double-layer paperboard tray according to claim 1, characterized in that: Pre-pressed folds (50) are provided between the first upper panel (11) and the first lower panel (12), and between the second upper panel (21) and the second lower panel (22) along the length direction, and the spacing between the pre-pressed folds (50) serves as the thickness of the upper base (10) or the lower base (20); pre-pressed folds (50) are also provided at the two long sides of the bonding portion, and the spacing between the long sides of the bonding portion and the pre-pressed folds (50) is adapted to the thickness of the upper base (10) or the lower base (20); the card slot (42) is provided on the pre-pressed folds (50); When squeezed inward from the left and right cardboard sections, the upper base (10) and the lower base (20) can quickly expand their thickness and form a double-layer structure of upper and lower layers.

3. The integrated double-layer paperboard tray according to claim 2, characterized in that: The height of the support tongue (31) does not exceed the spacing between the pre-pressed folds (50); the end of the support bar (32) is designed to be a trapezoidal surface with ridges, and after being inserted into the corresponding slot (42), the ridges can be stuck in the slot (42); the height of the trapezoidal surface is adapted to the thickness of the upper base (10).

4. The integrated double-layer paperboard tray according to claim 1, characterized in that: There are three or four supporting tongues (31) arranged along the four sides of the storage groove (30); the storage groove (30) is square, rectangular or of a special shape, and its spacing, depth and shape are adapted to the size and shape of the goods to be placed.

5. A rapid prototyping integrated double-layer paperboard support cardboard structure, characterized in that include: The inner support paperboard has a rectangular strip structure, and two first folds (51) are provided in the middle part. The bonding area is placed on the midline area of the middle part. The first lower panel (12) of the upper base (10) and the second upper panel (21) of the lower base (20), the thickness surface (55) of the upper base (10) and the lower base (20), the first upper panel (11) of the upper base (10) and the second lower panel (22) of the lower base (20), and the bonding ears (56) of the upper base (10) and the lower base (20) are formed in sequence along the middle part toward the two ends through the second folds (52), the third folds (53), and the fourth folds (54). A plurality of storage grooves (30) are provided on the first upper panel (11) of the upper base (10) and the second upper panel (21) of the lower base (20). A support tongue (31) that can be folded downward is provided on at least one side of the storage groove (30); and a support bar (32) that stands upright after being folded is located in or included in the storage groove (30) on the second upper panel (21).

6. The paperboard structure according to claim 5, characterized in that Slots (41) corresponding to the fold positions, number, and size of the support tongues (31) are provided on the first lower panel (12) of the upper base (10) and the second lower panel (22) of the lower base (20); after the commodity is placed in the storage slot (30), the support tongues (31) are pressed downward and folded, so that the ends of the support tongues (31) can be inserted into the slots (41) to form a support surface.

7. The paperboard structure according to claim 5, characterized in that The edge of the storage slot (30) near the edge of the second upper panel (21) of the lower base (20) is in a straight line with the third fold (53), and a support bar (32) is provided so that after the third fold (53) is folded, the support bar (32) is in an upward upright position and can be inserted into the card slot (42) provided on the third fold (53) on the upper base (10), thereby forming a support between the upper base (10) and the lower base (20).

8. The paperboard structure according to claim 7, characterized in that The length of the support bar (32) is set so that after it is inserted into the slot (42), the end surface can support the inner top surface of the upper base (10) and keep the upper base (10) and the lower base (20) parallel to each other.

9. The paperboard structure according to claim 5, characterized in that The support tongue (31) is arranged on at least one vertical edge of the storage groove (30), and the vertical edge is the edge on the side where the bottom surface of the cardboard inner tray is located when the goods are placed during use, and auxiliary support tongues (31) are also arranged on the other edges, and the height of the auxiliary support tongues (31) does not exceed the thickness of the base tray on which it is located.

10. The paperboard structure according to claim 5, characterized in that The end of the supporting tongue (31) is provided with a second adhesive portion (57), and the height of the supporting tongue (31) is adapted to the thickness of the base of the layer in which it is located, and the second adhesive portion (57) is adhered to the corresponding first lower panel (12) and second lower panel (22); so that when the upper base (10) and the lower base (20) are squeezed inward from the left and right cardboard intervals, the upper base (10) and the lower base (20) can quickly expand their thickness and form a double-layer structure of upper and lower layers, and the supporting tongue (31) can be synchronously stretched and folded to form a supporting surface in the storage groove (30).

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