Adjustable container corner fitting

Abstract

The utility model discloses an adjustable container corner fitting which comprises a first corner fitting body, a fourth corner fitting body is arranged at the bottom of the first corner fitting body, one side of the first corner fitting body and one side of the fourth corner fitting body are fixedly connected with first side baffles respectively, and the outer walls of the two first side baffles are fixedly connected with shells. The utility model relates to the technical field of container corner fittings, and the adjustable container corner fitting realizes the adjustment of the length of the first side baffle plate through the matching among the hand wheel, the threaded rod, the connecting plate, the first sliding block, the first inserting column, the first inserting hole and the first transverse column, so that containers with different lengths can be supported; the problems that when an existing container corner fitting is used, due to the fact that the length of a side baffle on the corner fitting is fixed, the length of the side baffle on the corner fitting cannot be adjusted, the existing corner fitting cannot support containers with different lengths, and the adjusting effect of the existing container corner fitting is reduced are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of container corner fittings, in particular to an adjustable container corner fitting. Background Technique

[0002] Container corner fittings are support members at the corners of containers, used to increase the stability and load-bearing capacity of containers.

[0003] For example, an adjustment structure of a container corner fitting with the application publication number of CN220316074U includes a corner fitting, a hydraulic rod at the bottom of the corner fitting and a base, and an adjusting rod for adjusting the base; although the above document can achieve the adjustment of the container to a horizontal state when encountering an irregular stacking environment, preventing the goods inside the container from being damaged, and the side plates on the four sides of the container prevent the container from falling off during transportation or horizontal adjustment;

[0004] However, when the existing container corner fittings are in use, the corner fittings are installed at the bottom of the container to support the container. Since the length of the side baffle on the corner fitting is fixed and the length of the side baffle on the corner fitting cannot be adjusted, the existing corner fittings cannot support containers of different lengths, thereby reducing the adjustment effect of the existing container corner fittings. Content of the Utility Model

[0005] Aiming at the deficiencies of the prior art, the utility model provides an adjustable container corner fitting, which solves the problem that when the existing container corner fittings are in use, since the length of the side baffle on the corner fitting is fixed and the length of the side baffle on the corner fitting cannot be adjusted, the existing corner fittings cannot support containers of different lengths, thereby reducing the adjustment effect of the existing container corner fittings.

[0006] To achieve the above object, the utility model is realized by the following technical solutions: An adjustable container corner fitting, including a first corner fitting, a fourth corner fitting is arranged at the bottom of the first corner fitting, first side baffles are respectively fixedly connected to one sides of the first corner fitting and the fourth corner fitting, outer shells are fixedly connected to the outer walls of the two first side baffles, a second corner fitting and a third corner fitting are respectively arranged at one ends of the two first side baffles far away from the first corner fitting and the fourth corner fitting, second side baffles are respectively fixedly connected to the bottoms of the first corner fitting and the second corner fitting, a first adjusting mechanism is arranged inside the outer shell, the first adjusting mechanism includes a handwheel, a threaded rod, a connecting plate, a first slider, a first inserting post, a first inserting hole and a first cross column, one end of the threaded rod is fixedly connected to the handwheel, the outer wall of the threaded rod is threadedly connected to the inner wall of the outer shell, the other end of the threaded rod far away from the handwheel is rotatably connected to the connecting plate through a bearing, the inner wall of the connecting plate is slidably clamped with the first slider, the back surface of the first slider is fixedly connected to the first inserting post, the outer wall of the first inserting post is inserted into the inner wall of the first side baffle, the outer wall of the first inserting post is inserted with the first inserting hole, the inner wall of the first side baffle is sleeved with the first cross column, the inner wall of the first cross column is provided with the first inserting hole, and one ends of the first cross column close to the outer shell are respectively fixedly connected to the outer walls of the second corner fitting and the third corner fitting.

[0007] Preferably, a second slider is fixedly connected to the outer wall of the connecting plate, and the outer wall of the second slider is slidably clamped with the inner wall of the outer shell.

[0008] Preferably, support legs are respectively fixedly connected to the back surfaces of the first corner fitting and the second corner fitting, and support legs are respectively fixedly connected to the back surfaces of the third corner fitting and the fourth corner fitting.

[0009] Preferably, a bottom plate is fixedly connected to one end of the support leg far away from the first corner fitting, the second corner fitting, the third corner fitting and the fourth corner fitting.

[0010] Preferably, mounting holes are respectively formed in the inner walls of the first corner fitting and the second corner fitting, mounting holes are respectively provided in the inner walls of the third corner fitting and the fourth corner fitting, and the mounting holes respectively penetrate through the first corner fitting, the second corner fitting, the third corner fitting and the fourth corner fitting.

[0011] Preferably, a second adjusting mechanism is provided outside the second side baffle. The second adjusting mechanism includes a rotary knob, a threaded column, a second plug post, a second jack, a second cross column and a vertical plate. The end of the threaded column is fixedly connected with the rotary knob. The outer wall of the threaded column is threadedly connected with the vertical plate. The side of the vertical plate away from the rotary knob fits against the outer wall of the second side baffle. The outer wall of the threaded column is threadedly connected to the inner wall of the second side baffle. A second plug post is fixedly connected to one side of the vertical plate. The outer wall of the second plug post is inserted into the inner wall of the second side baffle. The outer wall of the second plug post is inserted into the second jack. The inner wall of the second side baffle is sleeved with a second cross column. The second jack is opened on the inner wall of the second cross column. The bottom of the second cross column is fixedly connected to the outer walls of the third corner fitting and the fourth corner fitting respectively.

[0012] Beneficial effects

[0013] The utility model provides an adjustable container corner fitting, which has the following beneficial effects: through the cooperation among the hand wheel, the threaded rod, the connecting plate, the first slider, the first plug post, the first jack and the first cross column, the length of the first side baffle is adjusted, and containers of different lengths can be supported, solving the problem that when the existing container corner fitting is used, since the length of the side baffle on the corner fitting is fixed and the length of the side baffle on the corner fitting cannot be adjusted, the existing corner fitting cannot support containers of different lengths, thus reducing the adjustment effect of the existing container corner fitting.

[0014] Through the cooperation among the rotary knob, the threaded column, the second plug post, the second jack, the second cross column and the vertical plate, the length of the second side baffle is adjusted, and containers of different widths can be supported, solving the problem that the existing corner fitting cannot support containers of different widths. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic structural diagram of the utility model;

[0016] Figure 2 is Figure 1 the external view schematic diagram of;

[0017] Figure 3 is Figure 1 the schematic structural diagram of the first side baffle, the first cross column and the connecting plate in;

[0018] Figure 4 is Figure 1 the schematic structural diagram of the second side baffle, the second plug post and the threaded column in.

[0019] In the figure: 1. First corner fitting; 2. Second corner fitting; 3. Third corner fitting; 4. First side baffle; 5. Outer shell; 6. Handwheel; 7. Threaded rod; 8. Connecting plate; 9. First slider; 10. First insertion post; 11. First insertion hole; 12. First cross post; 13. Second slider; 14. Second side baffle; 15. Rotary knob; 16. Threaded post; 17. Second insertion post; 18. Second insertion hole; 19. Second cross post; 20. Vertical plate; 21. Mounting hole; 22. Support leg; 23. Bottom plate; 24. Fourth corner fitting. Detailed implementation mode

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0021] When the existing container corner fittings are in use, since the length of the side baffle on the corner fitting is fixed and cannot be adjusted, the existing corner fittings cannot support containers of different lengths, thereby reducing the adjustment effect of the existing container corner fittings.

[0022] In view of this, the present invention provides an adjustable container corner fitting. Through the cooperation among the handwheel, threaded rod, connecting plate, first slider, first insertion post, first insertion hole and first cross post, the length of the first side baffle can be adjusted, and containers of different lengths can be supported, solving the problem that when the existing container corner fittings are in use, since the length of the side baffle on the corner fitting is fixed and cannot be adjusted, the existing corner fittings cannot support containers of different lengths, thereby reducing the adjustment effect of the existing container corner fittings.

[0023] By those skilled in the art, the components in this case are connected in sequence. For the specific connection and operation sequence, reference should be made to the following working principle. The detailed connection means are well-known technologies in the art. The following mainly introduces the working principle and process.

[0024] Embodiment 1, consists of Figures 1-3It can be seen that an adjustable container corner fitting in this case includes a first corner fitting 1. A fourth corner fitting 24 is provided at the bottom of the first corner fitting 1. The first corner fitting 1, the second corner fitting 2, the third corner fitting 3 and the fourth corner fitting 24 support the container. First side baffles 4 are respectively fixedly connected to one side of the first corner fitting 1 and the fourth corner fitting 24. Outer shells 5 are fixedly connected to the outer walls of the two first side baffles 4. The second corner fitting 2 and the third corner fitting 3 are respectively provided at one ends of the two first side baffles 4 away from the first corner fitting 1 and the fourth corner fitting 24. Second side baffles 14 are respectively fixedly connected to the bottoms of the first corner fitting 1 and the second corner fitting 2. A first adjusting mechanism is provided inside the outer shell 5. The first adjusting mechanism includes a handwheel 6, a threaded rod 7, a connecting plate 8, a first slider 9, a first insertion post 10, a first insertion hole 11 and a first cross bar 12. One end of the threaded rod 7 is fixedly connected to the handwheel 6. The handwheel 6 drives the threaded rod 7 to rotate. The outer wall of the threaded rod 7 is threadedly connected to the inner wall of the outer shell 5. The other end of the threaded rod 7 away from the handwheel 6 is rotatably connected to the connecting plate 8 through a bearing. The threaded rod 7 drives the connecting plate 8 to move. The first slider 9 is slidably clamped inside the connecting plate 8. The connecting plate 8 drives the first slider 9 to slide in an inclined groove formed on the surface of the connecting plate 8. A first insertion post 10 is fixedly connected to the back of the first slider 9. The first slider 9 drives the first insertion post 10 to move. The outer wall of the first insertion post 10 is inserted into the inner wall of the first side baffle 4. The outer wall of the first insertion post 10 is inserted with a first insertion hole 11. When the first insertion post 10 leaves the current first insertion hole 11, the inner wall of the first side baffle 4 is sleeved with a first cross bar 12. The staff stops rotating the handwheel 6. The staff pulls the first cross bars 12 on the upper and lower sides. The first cross bars 12 move in the first side baffles 4. The inner walls of the first cross bars 12 are provided with first insertion holes 11. The first cross bars 12 on the upper and lower sides drive the first insertion holes 11 to move. One ends of the first cross bars 12 close to the outer shell 5 are respectively fixedly connected to the outer walls of the second corner fitting 2 and the third corner fitting 3. The first cross bars 12 on the upper and lower sides drive the second corner fitting 2 and the third corner fitting 3 to move to adjust the length of the first side baffle 4;

[0025] In the specific implementation process, it is particularly worth noting that the first corner fitting 1, the second corner fitting 2, the third corner fitting 3, and the fourth corner fitting 24 support the container. When it is necessary to support containers of different lengths, the staff rotates the handwheels 6 on the upper and lower sides in sequence. The handwheels 6 drive the threaded rods 7 to rotate, and the threaded rods 7 drive the connecting plates 8 to move. The connecting plates 8 drive the first sliders 9 to slide in the inclined slots opened on the surfaces of the connecting plates 8. The first sliders 9 drive the first insertion posts 10 to move. The first insertion posts 10 leave the current first insertion holes 11. The staff stops rotating the handwheels 6. The staff pulls down the first cross bars 12 on the upper and lower sides. The first cross bars 12 move in the first side baffle 4. The first cross bars 12 on the upper and lower sides drive the first insertion holes 11 to move. The first cross bars 12 on the upper and lower sides drive the second corner fitting 2 and the third corner fitting 3 to move, so as to adjust the length of the first side baffle 4. When the length of the first side baffle 4 is the same as the length of the container, at this time, the staff rotates the handwheels 6 in the reverse direction, thereby driving the first insertion posts 10 to insert into the corresponding first insertion holes 11, realizing the support for containers of different lengths;

[0026] Further, the outer wall of the connecting plate 8 is fixedly connected with a second slider 13. When the connecting plate 8 moves, the connecting plate 8 drives the second slider 13 to move. The outer wall of the second slider 13 is slidably clamped to the inner wall of the outer shell 5, and the second slider 13 slides in the limiting groove on the inner wall of the outer shell 5;

[0027] In the specific implementation process, it is particularly worth noting that when the connecting plate 8 moves, the connecting plate 8 drives the second slider 13 to move. The second slider 13 slides in the limiting groove on the inner wall of the outer shell 5, realizing the guiding of the connecting plate 8 and making the movement of the connecting plate 8 stable;

[0028] Further, the back surfaces of the first corner fitting 1 and the second corner fitting 2 are respectively fixedly connected with support legs 22. The back surfaces of the third corner fitting 3 and the fourth corner fitting 24 are respectively fixedly connected with support legs 22. The number of the support legs 22 is four, and the four support legs 22 support the four corner fittings;

[0029] In the specific implementation process, it is particularly worth noting that the number of the support legs 22 is four, and the four support legs 22 support the four corner fittings;

[0030] Further, one end of the support leg 22 far away from the first corner fitting 1, the second corner fitting 2, the third corner fitting 3, and the fourth corner fitting 24 is fixedly connected with a bottom plate 23. The number of the bottom plates 23 is four. The bottom plates 23 increase the contact area between the support legs 22 and the ground and improve the stability of the four corner fittings;

[0031] In the specific implementation process, it is particularly worth noting that the number of the bottom plates 23 is four. The bottom plates 23 increase the contact area between the support legs 22 and the ground and improve the stability of the four corner fittings;

[0032] Further, mounting holes 21 are respectively formed in the inner walls of the first corner fitting 1 and the second corner fitting 2, and mounting holes 21 are respectively provided in the inner walls of the third corner fitting 3 and the fourth corner fitting 24. The mounting holes 21 penetrate through the first corner fitting 1, the second corner fitting 2, the third corner fitting 3, and the fourth corner fitting 24 respectively. Two mounting holes 21 are formed in one corner fitting. The shape of the mounting holes 21 is circular, and the total number of the mounting holes 21 is eight. Workers install the four corner fittings onto the container through the mounting holes 21 to support the container.

[0033] In the specific implementation process, it is particularly noted that two mounting holes 21 are formed in one corner fitting. The shape of the mounting holes 21 is circular, and the total number of the mounting holes 21 is eight. Workers install the four corner fittings onto the container through the mounting holes 21 to support the container.

[0034] Specifically, first, the workers rotate the handwheels 6 on the upper and lower sides in sequence. The handwheels 6 drive the threaded rods 7 to rotate. The threaded rods 7 drive the connecting plates 8 to move. The connecting plates 8 drive the second sliders 13 to move. The second sliders 13 slide in the limiting grooves on the inner wall of the housing 5. The connecting plates 8 drive the first sliders 9 to slide in the inclined grooves formed on the surfaces of the connecting plates 8. The first sliders 9 drive the first plug posts 10 to move. The first plug posts 10 leave the current first jacks 11. The workers stop rotating the handwheels 6. The workers pull down the first cross bars 12 on the upper and lower sides. The first cross bars 12 move in the first side baffle 4. The first cross bars 12 on the upper and lower sides drive the first jacks 11 to move. The first cross bars 12 on the upper and lower sides drive the second corner fitting 2 and the third corner fitting 3 to move to adjust the length of the first side baffle 4. When the length of the first side baffle 4 is the same as the length of the container, at this time, the workers rotate the handwheels 6 in the reverse direction, thereby driving the first plug posts 10 to insert into the corresponding first jacks 11. Then the workers place the container on the four corner fittings. The workers install the four corner fittings onto the container through the mounting holes 21 to support the container. The four support legs 22 support the four corner fittings. The bottom plate 23 increases the contact area between the support legs 22 and the ground and improves the stability of the four corner fittings.

[0035] Example 2, consists of Figure 1 、 2As can be seen from FIGS. 1 and 4, a second adjusting mechanism is provided outside the second side baffle 14. The second adjusting mechanism includes a knob 15, a threaded column 16, a second insertion post 17, a second insertion hole 18, a second cross column 19 and a vertical plate 20. A knob 15 is fixedly connected to the end of the threaded column 16. The knob 15 drives the threaded column 16 to rotate. The threaded column 16 moves away from the second side baffle 14. A vertical plate 20 is threadedly connected to the outer wall of the threaded column 16. The side of the vertical plate 20 away from the knob 15 abuts against the outer wall of the second side baffle 14. The outer wall of the threaded column 16 is threadedly connected to the inner wall of the second side baffle 14. A second insertion post 17 is fixedly connected to one side of the vertical plate 20. The vertical plate 20 drives the second insertion post 17 to move. The outer wall of the second insertion post 17 is inserted into the inner wall of the second side baffle 14. A second insertion hole 18 is provided on the outer wall of the second insertion post 17. The second insertion post 17 moves away from the second insertion hole 18. A second cross column 19 is sleeved on the inner wall of the second side baffle 14. The staff pulls down the second cross columns 19 on both sides. The second cross columns 19 on both sides slide in the second side baffle 14. The second cross columns 19 on both sides drive the second insertion holes 18 to move. The bottoms of the second cross columns 19 are respectively fixedly connected to the outer walls of the third corner piece 3 and the fourth corner piece 24. The second cross columns 19 on both sides drive the third corner piece 3 and the fourth corner piece 24 to move;

[0036] In the specific implementation process, it is particularly pointed out that when it is necessary to support containers of different widths, the staff rotates the knobs 15 on the left and right sides in sequence. The knob 15 drives the threaded column 16 to rotate. The threaded column 16 moves away from the second side baffle 14. The staff moves the vertical plate 20. The vertical plate 20 drives the second insertion post 17 to move. The second insertion post 17 moves away from the second insertion hole 18. The staff pulls down the second cross columns 19 on both sides. The second cross columns 19 on both sides slide in the second side baffle 14. The second cross columns 19 on both sides drive the second insertion holes 18 to move. The second cross columns 19 on both sides drive the third corner piece 3 and the fourth corner piece 24 to move. When the length of the second side baffle 14 is the same as the width of the container, the staff inserts the second insertion post 17 into the corresponding second insertion hole 18. The staff rotates the knob 15 in the reverse direction, thereby driving the threaded column 16 to rotate back into the second side baffle 14 to fix the second insertion post 17, realizing the support for containers of different widths;

[0037] Specifically, when it is necessary to support containers of different widths, the staff members rotate the knobs 15 on the left and right sides in sequence. The knob 15 drives the threaded column 16 to rotate. The threaded column 16 moves out of the second side baffle 14. The staff member moves the vertical plate 20, and the vertical plate 20 drives the second insertion post 17 to move. The second insertion post 17 moves out of the second insertion hole 18. The staff member pulls down the second cross bars 19 on both sides. The second cross bars 19 on both sides slide in the second side baffle 14. The second cross bars 19 on both sides drive the second insertion hole 18 to move. The second cross bars 19 on both sides drive the third corner fitting 3 and the fourth corner fitting 24 to move. When the length of the second side baffle 14 is the same as the width of the container, the staff member inserts the second insertion post 17 into the corresponding second insertion hole 18. The staff member rotates the knob 15 in the reverse direction, thereby driving the threaded column 16 to rotate back into the second side baffle 14 to fix the second insertion post 17, realizing the support for containers of different widths and improving the application range of the corner fittings.

[0038] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation. An element defined by the statement "comprising an..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the element.

[0039] In the present utility model, unless otherwise clearly specified and defined, terms such as "installation", "setting", "connection", "fixation", "rotation connection" and the like shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium. It may be the communication inside two elements or the interaction relationship between two elements. Unless otherwise clearly defined, for those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0040] Although the embodiments of the present utility model have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present utility model. The scope of the present utility model is defined by the appended claims and their equivalents.

Claims

1. An adjustable container corner fitting, comprising a first corner fitting (1), characterized in that: A fourth corner piece (24) is provided at the bottom of the first corner piece (1); a first side baffle (4) is fixedly connected to one side of the first corner piece (1) and the fourth corner piece (24); outer walls of the two first side baffles (4) are fixedly connected to an outer shell (5); a second corner piece (2) and a third corner piece (3) are provided at one end of the two first side baffles (4) away from the first corner piece (1) and the fourth corner piece (24); a second side baffle (14) is fixedly connected to the bottom of the first corner piece (1) and the second corner piece (2); and a first adjustment mechanism is provided inside the outer shell (5); The first adjustment mechanism comprises a hand wheel (6), a threaded rod (7), a connecting plate (8), a first sliding block (9), a first plug post (10), a first plug hole (11) and a first cross post (12); One end of the threaded rod (7) is fixedly connected to a hand wheel (6), the outer wall of the threaded rod (7) is threadedly connected to the inner wall of the housing (5), the other end of the threaded rod (7) away from the hand wheel (6) is rotatably connected to a connecting plate (8) through a bearing, the inner wall of the connecting plate (8) is slidably connected to a first slider (9), the back of the first slider (9) is fixedly connected to a first plug post (10), the outer wall of the first plug post (10) is plugged into the inner wall of the first side baffle (4), the outer wall of the first plug post (10) is plugged into a first plug hole (11), the inner wall of the first side baffle (4) is sleeved with a first cross column (12), the inner wall of the first cross column (12) is provided with a first plug hole (11), and the end of the first cross column (12) close to the housing (5) is respectively fixedly connected to the outer wall of the second corner piece (2) and the outer wall of the third corner piece (3).

2. An adjustable container corner fitting according to claim 1, characterized in that: The outer wall of the connecting plate (8) is fixedly connected to a second sliding block (13), and the outer wall of the second sliding block (13) is slidably engaged with the inner wall of the outer shell (5).

3. An adjustable container corner fitting according to claim 1, characterized in that: The back surface of the first corner piece (1) and the back surface of the second corner piece (2) are respectively fixedly connected to support legs (22), and the back surface of the third corner piece (3) and the back surface of the fourth corner piece (24) are respectively fixedly connected to support legs (22).

4. An adjustable container corner fitting according to claim 3, characterized in that: One end of the support leg (22) away from the first corner piece (1), the second corner piece (2), the third corner piece (3) and the fourth corner piece (24) is fixedly connected to a bottom plate (23).

5. An adjustable container corner fitting according to claim 1, characterized in that: The inner wall of the first corner piece (1) and the inner wall of the second corner piece (2) are respectively provided with mounting holes (21), the inner wall of the third corner piece (3) and the inner wall of the fourth corner piece (24) are respectively provided with mounting holes (21), and the mounting holes (21) respectively penetrate the first corner piece (1), the second corner piece (2), the third corner piece (3) and the fourth corner piece (24).

6. An adjustable container corner fitting according to claim 5, characterized in that: A second adjustment mechanism is arranged outside the second side baffle (14); The second adjustment mechanism comprises a rotating knob (15), a threaded column (16), a second plug column (17), a second plug hole (18), a second cross column (19) and a vertical plate (20); The end of the threaded column (16) is fixedly connected to a knob (15), the outer wall of the threaded column (16) is threadedly connected to a vertical plate (20), the outer wall of the vertical plate (20) away from the knob (15) is attached to the outer wall of the second side baffle (14), the outer wall of the threaded column (16) is threadedly connected to the inner wall of the second side baffle (14), one side of the vertical plate (20) is fixedly connected to a second plug column (17), the outer wall of the second plug column (17) is plugged into the inner wall of the second side baffle (14), the outer wall of the second plug column (17) is plugged into a second insertion hole (18), the inner wall of the second side baffle (14) is sleeved with a second cross column (19), the second insertion hole (18) is opened on the inner wall of the second cross column (19), and the bottom of the second cross column (19) is respectively fixedly connected to the outer wall of the third corner piece (3) and the outer wall of the fourth corner piece (24).

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