Hidden button structure capable of preventing disassembly

Abstract

The utility model relates to the technical field of sockets, in particular to an anti-disassembly hidden buckle structure, which comprises a cover body and a seat body, the cover body comprises a flat plate and a plurality of assembly parts, each assembly part is provided with a concave buckling groove, the seat body comprises a shell and a plurality of positioning parts, the shell is provided with an accommodating area and a limiting area, the flat plate is clamped in the limiting area, the accommodating area is used for accommodating elements, the positioning parts are arranged on the inner wall of the accommodating area, and the positioning parts are used for positioning the flat plate. The positioning pieces are arranged in the containing area and correspond to the buckling grooves in a one-to-one mode, the top faces of the positioning pieces incline towards the center of the bottom of the containing area, inclined faces opposite to the top faces of the positioning pieces are arranged in the buckling grooves, a safety distance is reserved between the top faces of the positioning pieces and the inclined faces, and right-angle limiting parts are arranged at the bottoms of the positioning pieces. And the buckling groove is provided with a right-angle inner angle matched with the right-angle limiting part, and the cover body is connected with the seat body, so that the problems that information in the socket is easy to pry, and the production and the assembly of the socket shell are complicated are solved.

Description

Technical Field

[0001] This utility model relates to the field of socket technology, and in particular to a concealed snap-fit ​​structure that prevents disassembly. Background Technology

[0002] Currently, many sockets on the market have plastic casings. If a bottom cover is involved in the installation, it is usually fixed with screws or exposed clips. This method makes it easy to disassemble without damaging the socket casing. To prevent disassembly, easy-tear labels are used to cover the screw holes or clip gaps. These labels are destroyed once the bottom cover is removed. However, this structure does not secure the bottom cover well, making it easy for someone to disassemble it and see the internal information of the socket, reducing product security. At the same time, this structure is relatively cumbersome to install, resulting in low production and assembly efficiency. Utility Model Content

[0003] To address the aforementioned shortcomings, the purpose of this utility model is to propose a concealed snap-fit ​​structure that prevents disassembly, thereby solving the problems of easy access to information inside the socket and cumbersome production and assembly of the socket casing.

[0004] To achieve this objective, the present invention adopts the following technical solution:

[0005] A snap-fit ​​structure to prevent disassembly, comprising a cover and a base;

[0006] The cover includes a flat plate and several fittings. The flat plate and the fittings are an integrated structure. The fittings are located on the same side of the flat plate. Each fitting has a recessed fastening groove with only one opening, and the opening of the fastening groove faces the inner wall of the base.

[0007] The base includes a housing and several positioning components. The housing and the positioning components are an integral structure. The housing has a receiving area and a limiting area. The limiting area is located outside the receiving area. The wall thickness of the housing corresponding to the limiting area is greater than the wall thickness corresponding to the receiving area. The depth of the limiting area is equal to the thickness of the flat plate. The flat plate is fitted into the limiting area. The receiving area is used to receive components.

[0008] The positioning element is disposed on the inner wall of the receiving area and corresponds one-to-one with the fastening groove. The positioning element is used to relatively limit and fix the plate in the limiting area. The top surface of the positioning element is inclined to the bottom center of the receiving area. The fastening groove is provided with an inclined surface opposite to the top surface of the positioning element. A safety distance is left between the top surface of the positioning element and the inclined surface. The bottom of the positioning element is provided with a right-angle limiting part. The fastening groove is provided with a right-angled inner angle that cooperates with the right-angled limiting part. When the plate is snapped into the limiting area, at least one right-angled surface of the right-angled inner angle is in contact with one right-angled surface of the right-angled limiting part.

[0009] Preferably, the positioning element is a right-angled trapezoid, the inclined surface of the right-angled trapezoid is the top surface of the positioning element, the lower base of the right-angled trapezoid is connected to the inner wall of the base, the right-angled side surface of the right-angled trapezoid is the bottom surface of the positioning element, and when the flat plate is fitted into the limiting area, the two right-angled surfaces of the right-angled inner angle are respectively abutted to the two right-angled surfaces of the right-angled limiting part.

[0010] Furthermore, the inclined surface of the fastening groove is parallel to the top surface of the positioning member, and the safety distance is not less than 1mm.

[0011] Preferably, the positioning element is a right-angled triangular prism, with the inclined surface of the right-angled triangular prism being the top surface of the positioning element, one right-angled surface of the right-angled triangular prism being the bottom surface of the positioning element, and the other right-angled surface being fixedly connected to the inner wall of the base. The lower part of the fastening groove is perpendicular to the inner wall of the base.

[0012] Preferably, the housing is a cuboid without a top, the flat plate is a cuboid adapted to the shape of the housing, and there are four positioning members and four assembly members. Two positioning members form a group, and the two groups of positioning members are located on opposite sides of the inner wall of the housing.

[0013] Preferably, the tilt angle A of the top surface of the positioning member is 30-60°.

[0014] Preferably, when the flat plate is mounted in the limiting area, the minimum distance between the mounting part and the inner wall of the receiving area is 0.1 mm; the minimum distance between the depth of the fastening groove and the positioning part is 0.1 mm.

[0015] Preferably, the side thickness w1 of the assembly is 2-3 mm, and the middle thickness w2 of the assembly is 1-2 mm.

[0016] Preferably, the difference x between the wall thickness of the housing corresponding to the limiting area and the wall thickness corresponding to the receiving area is 1-2 mm.

[0017] The technical solution provided by this utility model can include the following beneficial effects:

[0018] The cover includes an assembly with a snap-fit ​​groove that matches the positioning element of the base. The base has a limiting area to relatively limit and fix the flat plate. When the cover and base are snapped together, the edges of the flat plate and the base are on the same plane, and the assembly and positioning element are located inside. The right-angled interior angle of the assembly is in contact with at least one right-angled surface of the right-angled limiting portion of the positioning element. Once the flat plate is snapped in, it cannot be disassembled without damage. The positioning element has a beveled surface, making assembly easier. Furthermore, the assembly has a recessed snap-fit ​​groove, ensuring that the snap-fit ​​between the positioning element and the assembly does not affect internal components. Attached Figure Description

[0019] Figure 1 This is a structural schematic diagram of one embodiment of the present invention.

[0020] Figure 2 This is a top view of one embodiment of the present invention.

[0021] Figure 3 yes Figure 2 Cross-sectional view of AA.

[0022] Figure 4 yes Figure 3 A magnified view of Q.

[0023] Figure 5 This is a structural schematic diagram of one embodiment of the present invention. (Cover body omitted)

[0024] Figure 6 This is a top view of one embodiment of the present invention. (Cover body omitted)

[0025] Figure 7 yes Figure 6 Cross-sectional view of BB in the middle.

[0026] Figure 8 This is a schematic diagram of another embodiment of the present invention. (Cover body omitted)

[0027] Figure 9 yes Figure 8 Cross-sectional view of CC.

[0028] Among them: cover 1, flat plate 11, assembly 12, fastening groove 121, seat 2, shell 21, limiting area 211, receiving area 212, positioning part 22, right angle limiting part 221. Detailed Implementation

[0029] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0030] In the description of this utility model, it should be understood that the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "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. They 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 on this utility model. Furthermore, features defined with "first" and "second" may explicitly or implicitly include one or more of these features, used to distinguish and describe features, without any order or emphasis.

[0031] 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.

[0032] The following is in conjunction with the accompanying drawings. Figures 1 to 9 The technical solution of this utility model will be further illustrated through specific implementation methods.

[0033] A snap-fit ​​structure to prevent disassembly includes a cover 1 and a base 2;

[0034] The cover 1 includes a flat plate 11 and several fittings 12. The flat plate 11 and the fittings 12 are an integral structure. The several fittings 12 are located on the same side of the flat plate 11. The fittings 12 are provided with recessed fastening grooves 121. The fastening grooves 121 have only one opening, and the opening of the fastening grooves 121 faces the inner wall of the seat 2.

[0035] The base 2 includes a housing 21 and a plurality of positioning members 22. The housing 21 and the positioning members 22 are an integral structure. The housing 21 is provided with a receiving area 212 and a limiting area 211. The limiting area 211 is located outside the receiving area 212. The wall thickness of the housing 21 corresponding to the limiting area 211 is greater than the wall thickness corresponding to the receiving area 212. The depth of the limiting area 211 is equal to the thickness of the plate 11. The plate 11 is fitted into the limiting area 211. The receiving area 212 is used to receive components.

[0036] The positioning member 22 is disposed on the inner wall of the receiving area 212 and corresponds one-to-one with the fastening groove 121. The positioning member 22 is used to relatively limit and fix the plate 11 in the limiting area 211. The top surface of the positioning member 22 is inclined to the bottom center of the receiving area 212. The fastening groove 121 is provided with an inclined surface opposite to the top surface of the positioning member 22. A safe distance is left between the top surface of the positioning member 22 and the inclined surface. The bottom of the positioning member 22 is provided with a right-angle limiting part 221. The fastening groove 121 is provided with a right-angled inner angle that cooperates with the right-angled limiting part 221. When the plate 11 is snapped into the limiting area 211, at least one right-angled surface of the right-angled inner angle is in contact with one right-angled surface of the right-angled limiting part 221.

[0037] To address the problems existing in the prior art, this technical solution proposes a concealed snap-fit ​​structure to prevent disassembly, fixing the component inside the socket housing, specifically within the receiving area 212, making it difficult to detect. The concealed snap-fit ​​structure includes a cover 1 and a base 2. The cover 1 includes a flat plate 11 and several fittings 12. The base 2 includes a housing 21 and several positioning elements 22. The fittings 12 are located on the same side of the flat plate 11 and have inwardly recessed engaging grooves 121. The positioning elements 22 are located on the inner wall of the housing 21. During assembly, the positioning elements 22 engage with the engaging grooves 121, with no gap between the right-angle limiting portion 221 at the bottom of the positioning element 22 and the lower part of the engaging groove 121. The right-angle limiting part 221 cooperates and restricts the right-angle interior angle. That is, the positioning part 22 limits the assembly part 12, thereby connecting and fixing the cover 1 and the base 2, and then clamping the plate 11. When the plate 11 is clamped in the limiting area 211, at least one right-angled surface of the right-angle interior angle is in contact with one right-angled surface of the right-angle limiting part 221, realizing a tight connection between the two, restricting the movement of the plate 11, enhancing the overall strength of the structure, providing sufficient resistance, and ensuring that the plate 11 cannot be disassembled without damage. Furthermore, since the positioning element 22 and the mounting element 12 are both located inside after being fastened, the fastening structure between the cover 1 and the base 2 cannot be known, thus effectively preventing disassembly. At the same time, the housing 21 is provided with a limiting area 211, and the flat plate 11 is fastened to the limiting area 211. The edge of the flat plate 11 and the edge of the housing 21 are on the same plane, so that there is no force point on the outside of the product after fastening to disassemble the cover 1, which greatly improves the safety of the components in the receiving area 212 and the overall confidentiality of the product. The limiting area 211 and the positioning element 22 together limit and fix the cover 1 relatively, solving the problem in the prior art that the internal information of the socket is easily spied on.

[0038] Furthermore, the positioning element 22 corresponds one-to-one with the fastening groove 121, and the shape of the positioning element 22 and the fastening groove 121 are adapted to each other. During assembly, the cover 1 can be pressed and fastened directly according to the position of the positioning element 22 and the shape of the limiting area 211. The top surface of the positioning element 22 is an inclined surface. When pressed and fastened, the assembly 12 can slide down along the top surface of the positioning element 22. The inclined surface of the top surface of the positioning element 22 can cause the assembly 12 to deform, and the assembly 12 moves towards the container. The receiving area 212 is inclined internally, allowing it to smoothly reach the desired position and engage the positioning element 22 into the fastening groove 121, achieving rapid positioning and assembly and improving assembly efficiency. Simultaneously, the fastening groove 21 has an inclined surface opposite to the top surface of the positioning element 22, with a safe distance between the top surface of the positioning element 22 and the inclined surface. This allows for higher assembly precision and prevents the cover 1 from failing to be properly secured due to mismatch between the top surface of the positioning element 22 and the fastening groove 121, thus improving the connection strength between the cover 1 and the base. Furthermore, the safe distance reduces production difficulty, mold processing difficulty, and the risk of interference between the assembly element 12 and the positioning element 22, preventing the cover 1 from loosening from the base 2. The positioning element 22 is located on the wall of the receiving area 212, reducing the likelihood of injection molding defects caused by placing the fastening structure at the edge of the base 2, thus solving the problem of cumbersome production and assembly of socket shells in the prior art.

[0039] In addition, the fastening groove 121 has only one opening, and the opening of the fastening groove 121 faces the inner wall of the seat 2, so it can fasten the positioning member 22 located on the inner wall of the receiving area 212. Moreover, since there is only one opening, the stability of the connection and fastening point is improved. Furthermore, the connection and fastening between the assembly 12 and the positioning member 22 will not affect the components in the receiving area 212, thus playing a certain protective role.

[0040] Preferably, the positioning element 22 is a right-angled trapezoid, the inclined surface of the right-angled trapezoid is the top surface of the positioning element 22, the bottom surface of the right-angled trapezoid is connected to the inner wall of the base 2, the right-angled side surface of the right-angled trapezoid is the bottom surface of the positioning element 22, and when the plate 11 is fitted into the limiting area 211, the two right-angled surfaces of the right-angled inner angle are respectively in contact with the two right-angled surfaces of the right-angled limiting part 221.

[0041] It is worth noting that the right-angled trapezoid is a regular shape, which is beneficial for large-scale production and reduces injection molding defects. The right-angled side of the right-angled trapezoid is perpendicular to the inner wall of the base 2. The fastening groove 121 has a corresponding right angle that matches the right-angled trapezoid. That is, the contact surface between the lower part of the fastening groove 121 of the mounting part 12 and the positioning member 22 is perpendicular to the inner wall of the base 2. The limiting area 211 applies a vertically upward force to the cover 1, and the positioning member 22 applies a vertically downward force to the cover 1, which together fix the cover 1 in place and effectively prevent disassembly.

[0042] In addition, the two right-angled surfaces of the right-angled interior angle are respectively attached to the two right-angled surfaces of the right-angled limiting part 221, which further increases the disassembly resistance. After the plate 11 is installed, it cannot be disassembled without damage due to the structural arrangement between the positioning part 22 and the assembly part 12, thus achieving the purpose of protecting the internal components.

[0043] Furthermore, the inclined surface of the fastening groove 121 is parallel to the top surface of the positioning member 22, and the safety distance is not less than 1mm.

[0044] Specifically, the inclined surface of the right-angled trapezoid is parallel to the inclined surface of the fastening groove 121. A safety distance is left between the top surface of the positioning member 22 and the inclined surface, and the safety distance is not less than 1mm. After the positioning member 22 is inserted into the fastening groove 121, except for the interaction force between the lower part of the fastening groove 121 and the positioning member 22, the upper part of the fastening groove 121 will not interfere with the fastening of the positioning member 22, ensuring that the positioning member 22 is fastened in place.

[0045] Preferably, the positioning element 22 is a right-angled triangular prism, with the inclined surface of the right-angled triangular prism being the top surface of the positioning element 22, one right-angled surface of the right-angled triangular prism being the bottom surface of the positioning element 22, and the other right-angled surface being fixedly connected to the inner wall of the seat body 2, and the lower part of the fastening groove 121 being perpendicular to the inner wall of the seat body 2.

[0046] Specifically, the contact surface between the lower part of the snap-fit ​​groove 121 and the right-angled surface of the right-angled triangular prism is perpendicular to the inner wall of the seat 2, and together with the limiting area 211, they achieve the snap-fit ​​function. The positioning member 22 is a right-angled triangular prism, with the inclined surface of the right-angled triangular prism being the top surface of the positioning member 22 and one right-angled surface being the bottom surface of the positioning member 22. When the assembly 12 moves and deforms along the inclined surface of the right-angled triangular prism to reach the desired position, the top surface and the bottom surface of the positioning member 22 are in contact, and the assembly 12 can quickly snap the positioning member 22.

[0047] Preferably, the housing 21 is a cuboid without a top, the flat plate 11 is a cuboid adapted to the shape of the housing 21, and there are four positioning members 22 and four mounting members 12. Two positioning members 22 form a group, and the two groups of positioning members 22 are located on opposite sides of the inner wall of the housing 21.

[0048] Specifically, the engagement of the positioning element 22 and the mounting part 12 fastens the cover 1 and the base 2 together, as shown below. Figure 6 As shown, there are four positioning elements 22, which are distributed in pairs on opposite sides of the inner wall of the housing 21. During assembly, the positioning elements 22 on opposite sides can improve the positioning accuracy, ensure that the fastening groove 121 is in the correct position and is properly fastened and fixed with the positioning element 22, reduce errors during assembly, and at the same time help maintain the balance of the overall structure and improve stability.

[0049] Preferably, when the housing 21 is a cylinder without a top, the positioning members 22 are distributed at 360-degree equal angles according to the required number of latches.

[0050] Preferably, the tilt angle A of the top surface of the positioning member 22 is 30-60°.

[0051] Specifically, under external force conditions, the fitting 12 will slide along the inclined surface of the positioning member 22. Within this angle range, the fitting 12 can quickly reach the required position, reducing the situation where the fitting 12 is difficult to deform due to the large angle, making it impossible for the cover 1 to be successfully fastened to the seat 2. It also ensures that the fitting 12 is not easy to fall off after being fastened to the positioning member 22.

[0052] Preferably, when the flat plate 11 is fitted into the limiting area 211, the minimum distance between the mounting part 12 and the inner wall of the receiving area 212 is 0.1mm; the minimum distance between the depth of the fastening groove 121 and the positioning part 22 is 0.1mm.

[0053] The minimum distance between the fitting 12 and the inner wall of the receiving area 212, and between the depth of the fastening groove 121 and the positioning member 22, is defined as an installation gap. This minimum distance is limited to 0.1 mm, which facilitates the assembly of the fitting 12 and the positioning member 22. During assembly, the fitting 12 slides along the top surface of the positioning member 22 and deforms until it reaches the desired position. After that, the fitting 12 returns to its original state, thereby fastening the positioning member 22 into the fastening groove 121. The installation gap between the fitting 12 and the receiving area 212 effectively avoids interference between the fitting 12 and the inner wall of the receiving area 212, preventing the cover 1 from being fastened to the seat 2. This ensures a smooth assembly process, improves production efficiency, reduces wear between the fitting 12 and the inner wall of the seat 2, and reduces the risk of structural damage to the fitting 12 and the positioning member 22 due to stress concentration.

[0054] Furthermore, the side thickness w1 of the assembly 12 is 2-3 mm, and the middle thickness w2 of the assembly 12 is 1-2 mm.

[0055] Specifically, the socket casing is made of plastic, such as Figure 3 As shown, the thickness w2 of the middle part of the assembly 12 is 1-2mm, and the thickness w1 of the side part is 2-3mm. Within this thickness range, the assembly 12 can maintain excellent elasticity and strength. It can deform rapidly after being subjected to external force without damaging the overall structure. After reaching the required position, it can quickly return to its original state, which is conducive to assembly and improves assembly efficiency.

[0056] In addition, the thickness w2 of the middle part of the fitting 12 is 1-2mm to ensure that it does not affect the components located in the receiving area 212, and to separate the positioning member 22 from the internal components. The fastening between the cover 1 and the seat 2 does not affect the internal components.

[0057] Furthermore, the difference x between the wall thickness of the housing 21 corresponding to the limiting area 211 and the wall thickness corresponding to the receiving area 212 is 1-2 mm.

[0058] like Figure 7 As shown, the difference between the wall thickness of the housing 21 corresponding to the limiting area 211 and the wall thickness corresponding to the receiving area 212 is 1-2 mm. The change in the wall thickness of the housing 21 ensures that the plate 11 is confined within the limiting area 211, reducing the possibility of the plate 11 getting stuck in the receiving area 212 and affecting the internal components. It also reduces the material consumption in the production of the base 2, lowers the cost, and avoids waste.

[0059] The technical principles of this utility model have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of this utility model and should not be construed as limiting the scope of protection of this utility model in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of this utility model without any inventive effort, and these embodiments will all fall within the scope of protection of this utility model.

Claims

1. A tamper-evident snap structure, characterized by: The cover and the base body are included; The cover includes a flat plate and several assembling pieces, the flat plate and the assembling pieces are integrated structure, several assembling pieces are located on the same side of the flat plate, the assembling piece is provided with a recessed buckle groove, the buckle groove has only one opening, and the opening of the buckle groove faces the inner wall of the base body; The base body includes a shell and several positioning pieces, the shell and the positioning pieces are integrated structure, the shell is provided with a containing area and a limiting area, the limiting area is located outside the containing area, the wall thickness of the shell corresponding to the limiting area is greater than the wall thickness corresponding to the containing area, the depth of the limiting area is equal to the thickness of the flat plate, the flat plate is clamped in the limiting area, and the containing area is used for containing elements; The positioning piece is arranged on the inner wall of the containing area and corresponds to the buckle groove, the positioning piece is used for relatively limiting and fixing the flat plate in the limiting area, the top surface of the positioning piece is inclined to the center of the bottom of the containing area, the buckle groove is provided with an inclined surface opposite to the top surface of the positioning piece, a safety distance is left between the top surface of the positioning piece and the inclined surface, the bottom of the positioning piece is provided with a right-angle limiting part, the buckle groove is provided with a right-angle inner corner matched with the right-angle limiting part, and at least one right-angle surface of the right-angle inner corner is attached to one right-angle surface of the right-angle limiting part when the flat plate is clamped in the limiting area.

2. The tamper-resistant clasp structure of claim 1, wherein: The positioning piece is a right-angle trapezoidal body, the inclined surface of the right-angle trapezoidal body is the top surface of the positioning piece, the lower bottom surface of the right-angle trapezoidal body is connected with the inner wall of the base body, the right-angle side surface of the right-angle trapezoidal body is the bottom surface of the positioning piece, and two right-angle surfaces of the right-angle inner corner are respectively attached to two right-angle surfaces of the right-angle limiting part when the flat plate is clamped in the limiting area.

3. A tamper-evident snap structure according to claim 2, wherein: The inclined surface of the buckle groove is parallel to the top surface of the positioning piece, and the safety distance is not less than 1 mm.

4. The tamper-resistant clasp structure of claim 1, wherein: The positioning piece is a right-angle triangular column, the inclined surface of the right-angle triangular column is the top surface of the positioning piece, one right-angle surface of the right-angle triangular column is the bottom surface of the positioning piece, and the other side right-angle surface is fixedly connected with the inner wall of the base body, and the lower part of the buckle groove is perpendicular to the inner wall of the base body.

5. The tamper-resistant clasp structure of claim 1, wherein: The shell is a rectangular body without a top, the flat plate has a shape of a rectangular body adapted to the shell, the number of the positioning pieces and the assembling pieces is 4 respectively, two positioning pieces form a group, and two groups of positioning pieces are located on opposite sides of the inner wall of the shell.

6. The tamper-resistant clasp structure of claim 1, wherein: The inclination angle A of the top surface of the positioning piece is 30-60°.

7. The tamper-resistant clasp structure of claim 1, wherein: When the flat plate is clamped in the limiting area, the minimum distance between the assembling piece and the inner wall of the containing area is 0.1 mm, and the minimum distance between the deep part of the buckle groove and the positioning piece is 0.1 mm.

8. The tamper-resistant clasp structure of claim 1, wherein: The side thickness w1 of the assembling piece is 2-3 mm, and the middle thickness w2 of the assembling piece is 1-2 mm.

9. The tamper-resistant clasp structure of claim 1, wherein: The difference x between the wall thickness of the shell corresponding to the limiting area and the wall thickness corresponding to the containing area is 1-2 mm.

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