Unloading platform

Abstract

The invention relates to the field of lifting devices, in particular to an unloading platform which comprises a bottom layer frame, a middle layer frame, a top layer frame, a lifting mechanism, a first turning plate, a second turning plate, a first limiting assembly and a second limiting assembly. A first limiting assembly capable of adjusting the height and changing the limiting position and the non-limiting position is arranged and used for limiting or not limiting the position, the height and the angle relative to the ground of a first turning plate, and a second limiting assembly capable of adjusting the height and changing the limiting position and the non-limiting position is arranged and used for limiting or not limiting the position, the height and the angle relative to the ground of a second turning plate. The unloading platform can be suitable for the scene of transporting a truck and a platform and the scene of transporting the truck and the ground.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lifting devices, in particular to a unloading platform. BACKGROUND

[0002] In the prior art, a patent document with the title of a fixed unloading platform convenient to install and disassemble, application number 202420961502.X is provided; in the prior art, the unloading platform is arranged between the platform and the transport truck.

[0003] However, the above-mentioned prior art is only applicable to the scenario of the transport truck and the platform; if in the scenario of the truck and the ground, the above-mentioned prior art is not applicable.

[0004] Therefore, how to provide an unloading platform that can be respectively applicable to the scenarios of the transport truck and the platform and the transport truck and the ground becomes a technical problem to be solved. SUMMARY

[0005] To solve the technical problem of how to provide an unloading platform that can be respectively applicable to the scenarios of the transport truck and the platform and the transport truck and the ground, the present application provides an unloading platform.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] According to one aspect of the present application, an unloading platform is provided, comprising a bottom frame, a middle frame, a top frame, a lifting mechanism, a first flap, a second flap, a first limiting component and a second limiting component, the first limiting component and the second limiting component respectively have a limiting position and a non-limiting position relative to the middle frame;

[0008] The unloading platform is arranged in a three-dimensional coordinate system for reference;

[0009] Along the Z-axis of the three-dimensional coordinate system, the bottom frame is located below the middle frame, the top frame is located above the middle frame, and the lifting mechanism is used to change the height of the top frame relative to the middle frame;

[0010] Along the X-axis of the three-dimensional coordinate system, the first flap and the second flap are respectively rotatably arranged at both ends of the top frame, and the first limiting component and the second limiting component are respectively adjustably arranged at both ends of the middle frame, wherein the top frame is provided with an unloading flat plate, the unloading flat plate is located between the first flap and the second flap, and the first flap and the second flap are located between the first limiting component and the second limiting component;

[0011] The distance of the first limiting assembly relative to the ground along the Z axis of the three-dimensional coordinate system is defined as a first height threshold, which is limited to any value between a first lower limit and a first upper limit, the first lower limit is specifically 40 cm, and the first upper limit is specifically 160 cm. The distance of the second limiting assembly relative to the ground is defined as a second height threshold, which is limited to any value between a second lower limit and a second upper limit, the second lower limit is specifically 40 cm, and the second upper limit is specifically 120 cm.

[0012] Under the condition of meeting the first height threshold, the first limiting assembly is used to limit the angle of the first flap relative to the unloading flat plate, and under the condition of meeting the second height threshold, the second limiting assembly is used to limit the angle of the second flap relative to the unloading flat plate.

[0013] Further, the first limiting assembly comprises a first adjusting rod, a first limiter and a second limiter.

[0014] The extension direction of the first adjusting rod is parallel to the Z axis of the three-dimensional coordinate system, and the first adjusting rod is fixedly or detachably arranged on the middle layer frame.

[0015] The first limiter comprises a first sliding sleeve, a first locking bolt and a first pulley. The first sliding sleeve is sleeved on the first adjusting rod, and the first sliding sleeve is configured as a sliding pair and a rotating pair relative to the first adjusting rod. The first locking bolt is used to adjust the looseness or locking of the first sliding sleeve relative to the first adjusting rod. The first pulley is arranged on the first sliding sleeve, wherein the circumferential surface of the first pulley is used to be contacted by the first flap.

[0016] The second limiter comprises two second sliding sleeves, a third sliding sleeve, a first limiting sleeve, a first limiting rod, two second locking bolts, a third locking bolt and three second pulleys.

[0017] The two second sliding sleeves and the third sliding sleeve are respectively sleeved on the first adjusting rod, and the two second sliding sleeves and the third sliding sleeve are respectively configured as a sliding pair and a rotating pair relative to the first adjusting rod.

[0018] Two ends of the first limiting sleeve are respectively fixedly connected to one of the second sliding sleeves, one end of the first limiting rod is fixedly connected to the third sliding sleeve, and along the negative direction of the Z axis of the three-dimensional coordinate system, the other end of the first limiting rod is inserted into the first limiting sleeve. The total length of the first limiting rod and the first limiting sleeve is greater than or equal to twice the length of the first flap, and the length of the first limiting sleeve is less than or equal to the length of the first flap.

[0019] Two of the second sliding sleeves and the third sliding sleeve are respectively provided with one of the second pulleys, and the two of the second sliding sleeves and the third sliding sleeve are respectively adjusted to be loosened or locked relative to the first adjusting rod by one of the second locking bolts, wherein the first limiting sleeve is provided with a first limiting surface tangent to the circumferential surface of the second pulley of the two of the second sliding sleeves, the first limiting rod is provided with a second limiting surface tangent to the circumferential surface of the second pulley of the third sliding sleeve, and the circumferential surfaces of the three second pulleys, the first limiting surface and the second limiting surface are respectively used to be contacted by the first flap;

[0020] The first height threshold includes a first intermediate value and a second intermediate value, and the first lower limit value, the first intermediate value, the second intermediate value and the first upper limit value are arranged in an increasing manner;

[0021] The difference between the first intermediate value and the first lower limit value is equal to or less than the length of the first flap, and between the first lower limit value and the first intermediate value, the first limiter is used to limit the angle of the first flap relative to the unloading flat plate;

[0022] The difference between the second intermediate value and the first intermediate value is equal to or less than the length of the first flap, the difference between the first upper limit value and the second intermediate value is equal to or less than the length of the first flap, between the first intermediate value and the second intermediate value, and between the first upper limit value and the first intermediate value, the second limiter is used to limit the angle of the first flap relative to the unloading flat plate.

[0023] Further, the second limiting assembly includes a second adjusting rod, a third limiter and a fourth limiter;

[0024] The extension direction of the second adjusting rod is parallel to the Z-axis of the three-dimensional coordinate system, and the second adjusting rod is fixedly or detachably arranged on the middle layer frame;

[0025] The third limiter includes a fourth sliding sleeve, a fifth sliding sleeve, two fourth locking bolts, two third pulleys and a first limiting ruler;

[0026] The fourth sliding sleeve and the fifth sliding sleeve are respectively sleeved on the second adjusting rod, and the fourth sliding sleeve and the fifth sliding sleeve are respectively configured as a sliding pair and a rotating pair relative to the second adjusting rod;

[0027] One end of the first limiting ruler is connected to the fourth sliding sleeve, the connection position of the first limiting ruler and the fifth sliding sleeve is located between the two ends of the first limiting ruler, the fifth sliding sleeve is located below the fourth sliding sleeve, and the length of the first limiting ruler is greater than or equal to the length of the second flap.

[0028] The fourth sliding sleeve and the fifth sliding sleeve are respectively adjusted to be loosened or locked relative to the second adjusting rod by one of the fourth locking bolts, and the fourth sliding sleeve and the fifth sliding sleeve are respectively provided with one of the third pulleys, wherein the first limiting scale has a third limiting surface which is tangent to the circumferential surfaces of the two third pulleys, and the third limiting surface and the circumferential surfaces of the two third pulleys are respectively used to be contacted by the second flap;

[0029] The fourth limiter comprises a sixth sliding sleeve, a fifth locking bolt and a fourth pulley, the sixth sliding sleeve is sleeved on the second adjusting rod, the sixth sliding sleeve is configured as a sliding pair and a rotating pair relative to the second adjusting rod, the fifth locking bolt is used to adjust the sixth sliding sleeve to be loosened or locked relative to the second adjusting rod, and the fourth pulley is arranged on the sixth sliding sleeve, wherein a circumferential surface of the fourth pulley is used to be contacted by the second flap;

[0030] The second height threshold value comprises a third intermediate value, a second lower limit value, the third intermediate value and the second upper limit value are arranged in an increasing manner;

[0031] The difference between the third intermediate value and the second lower limit value is equal to or less than the length of the second flap, and between the second lower limit value and the third intermediate value, the fourth limiter is used to limit the angle of the second flap relative to the unloading flat plate;

[0032] The difference between the second upper limit value and the third intermediate value is equal to or less than the length of the second flap, and between the second upper limit value and the third intermediate value, the third limiter is used to limit the angle of the second flap relative to the unloading flat plate.

[0033] Further, the length of the first flap and the length of the second flap are respectively 40 cm;

[0034] The first intermediate value is specifically 80 cm, the second intermediate value is specifically 120 cm, and the third intermediate value is specifically 80 cm.

[0035] Further, the bottom frame is provided with a horizontal hydraulic cylinder and a plurality of rollers;

[0036] The axis of each roller is parallel to the Y axis of the three-dimensional coordinate system, each roller is rotatably connected to the bottom frame, and all the rollers are tangent to the same horizontal movement plane.

[0037] The horizontal hydraulic cylinder has a horizontal cylinder barrel, a horizontal piston and a horizontal hydraulic rod, two ends of the horizontal hydraulic rod are located outside the horizontal cylinder barrel respectively, an intersection of the horizontal hydraulic rod and the horizontal piston is located inside the horizontal cylinder barrel, a length direction of the horizontal hydraulic rod and a length direction of the horizontal cylinder barrel are parallel to an X axis of the three-dimensional coordinate system respectively, the horizontal cylinder barrel is fixedly connected with the bottom layer frame, and two ends of the horizontal hydraulic rod are detachably connected with the middle layer frame respectively.

[0038] Further, the lifting mechanism comprises four positioning columns, four vertical hydraulic cylinders and four pushing components, each of the pushing components is provided with a chain wheel and a chain respectively;

[0039] The extending directions of the positioning columns are parallel to a Z axis of the three-dimensional coordinate system respectively, and the positioning columns are arranged on the middle layer frame respectively.

[0040] The vertical hydraulic cylinder comprises a vertical hydraulic rod, a vertical piston and a vertical cylinder barrel, two ends of the vertical hydraulic rod are located outside the vertical cylinder barrel respectively, an intersection of the vertical hydraulic rod and the vertical piston is located inside the vertical cylinder barrel, a length direction of the vertical hydraulic rod and a length direction of the vertical cylinder barrel are parallel to the Z axis of the three-dimensional coordinate system respectively, and the vertical hydraulic rod is fixedly connected with the middle layer frame.

[0041] The vertical cylinder barrel is used for pushing the pushing component along the Z axis of the three-dimensional coordinate system.

[0042] The chain wheel and the chain constitute a transmission pair, one end of the chain is connected to the middle layer frame, and the other end of the chain is connected to the top layer frame.

[0043] Further, the lifting mechanism further comprises four stop components.

[0044] Each of the positioning columns is provided with one of the stop components, the stop components are located below the pushing components along the Z axis of the three-dimensional coordinate system, and a spacing is formed between the stop components and the middle layer frame.

[0045] Further, each of the pushing components is provided with a first positioning wheel and a second positioning wheel, and the first positioning wheel and the second positioning wheel are rotatably connected to the pushing component respectively.

[0046] The positioning column has a first side plate, a second side plate and a connecting plate, the first side plate and the second side plate are parallel to each other, the connecting plate is located between the first side plate and the second side plate, and the first side plate, the connecting plate and the second side plate constitute an I-shaped steel structure.

[0047] The first positioning wheel is limited to contact the first side plate, and the second positioning wheel is limited to contact the second side plate.

[0048] Further, four first universal wheels and four supporting feet are further included, each of the supporting feet is welded to one corner of the bottom frame, and each of the first universal wheels is connected to the bottom frame and one of the supporting feet.

[0049] Further, four second rollers, four telescopic assemblies, multiple load-bearing plates and multiple load-bearing wheels are further included.

[0050] Each of the telescopic assemblies includes a spring, a positioning sleeve and a transmission rod, the positioning sleeve is welded to the middle frame, the length direction of the positioning sleeve is parallel to the Z axis of the three-dimensional coordinate system, and the transmission rod and the positioning sleeve form a sleeve structure, wherein, along the Z axis of the three-dimensional coordinate system, the transmission rod has a top end that can be exposed on the upper part of the middle frame and a bottom end that can be exposed on the lower part of the middle frame, the top end is provided with a stepped portion, the diameter of the stepped portion is greater than the diameter of the transmission rod, and the bottom end is provided with one of the second rollers.

[0051] Each of the vertical cylinders is provided with a driving component, and the driving component is welded to the vertical cylinder, wherein, along the direction from the top end to the bottom end, the driving component is used to drive the transmission rod.

[0052] The middle frame is provided with two load-bearing rails, the length direction of each of the load-bearing rails is parallel to the X axis of the three-dimensional coordinate system, the two load-bearing rails are separated by the bottom frame, and the two load-bearing rails are parallel to each other.

[0053] The multiple load-bearing plates are divided into two groups, the load-bearing plates in the first group and the load-bearing plates in the second group are separated by the bottom frame, one end of each of the load-bearing plates is fixedly or detachably connected to the bottom frame, and the other end of each of the load-bearing plates is rotatably provided with one of the load-bearing wheels, wherein, along the direction from the top end to the bottom end, each of the load-bearing wheels is in contact with one of the load-bearing rails.

[0054] The above technical scheme has the following advantages or beneficial effects:

[0055] The unloading platform provided by the present application can be applied to the scene of a transport truck and a platform, and the scene of a transport truck and the ground, by setting the first limiting component which can adjust the height and change the limiting position and non-limiting position, for limiting or not limiting the position, height and angle relative to the ground of the first flap, and by setting the second limiting component which can adjust the height and change the limiting position and non-limiting position, for limiting or not limiting the position, height and angle relative to the ground of the second flap. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 The structural schematic diagram of the unloading platform provided by the embodiment of the present application is shown in the figure.

[0057] Figure 2 The structural schematic diagram of the unloading platform provided by the embodiment of the present application is shown in the figure.

[0058] Figure 3 The structural schematic diagram of the unloading platform provided by the embodiment of the present application is shown in the figure.

[0059] Figure 4 The structural schematic diagram of the unloading platform provided by the embodiment of the present application is shown in the figure.

[0060] Figure 5 The structural schematic diagram of the unloading platform provided by the embodiment of the present application is shown in the figure.

[0061] Figure 6 The structural schematic diagram of the unloading platform provided by the embodiment of the present application is shown in the figure.

[0062] Figure 7 The structural schematic diagram of the unloading platform provided by the embodiment of the present application is shown in the figure.

[0063] Figure 8 The structural schematic diagram of the unloading platform provided by the embodiment of the present application is shown in the figure.

[0064] Figure 9 The structural schematic diagram of the unloading platform provided by the embodiment of the present application is shown in the figure.

[0065] Figure 10 The structural schematic diagram of the unloading platform provided by the embodiment of the present application is shown in the figure.

[0066] REFERENCE NUMERALS:

[0067] 1, bottom frame; 2, middle layer frame; 3, top layer frame; 4, lifting mechanism; 5, first flap; 6, second flap; 7, first limiting component; 8, second limiting component; 9, horizontal hydraulic cylinder; 10, roller; 11, first universal wheel; 12, supporting foot; 13, second roller; 14, telescopic component; 15, bearing plate; 16, bearing wheel; 17, driving component; 18, bearing rail;

[0068] 141, spring; 142, positioning sleeve; 143, transmission rod;

[0069] 31, unloading platform;

[0070] 41, positioning column; 42, vertical hydraulic cylinder; 43, pushing part; 44, chain wheel; 45, chain; 46, stop part; 47, first positioning wheel; 48, second positioning wheel;

[0071] 411, first side plate; 412, second side plate; 413, connecting plate; 421, vertical hydraulic rod; 422, vertical cylinder;

[0072] 71, first adjusting rod; 72, first limiter; 73, second limiter;

[0073] 721, first sliding sleeve; 722, first locking bolt; 723, first pulley; 731, second sliding sleeve; 732, third sliding sleeve; 733, first limiting sleeve; 734, first limiting rod; 735, second locking bolt; 736, third locking bolt; 737, second pulley;

[0074] 81, second adjusting rod; 82, third limiter; 83, fourth limiter;

[0075] 821, fourth sliding sleeve; 822, fifth sliding sleeve; 823, fourth locking bolt; 825, third pulley; 826, first limiting ruler; 831, sixth sliding sleeve; 832, fifth locking bolt; 833, fourth pulley;

[0076] 91, horizontal cylinder; 93, horizontal hydraulic rod. DETAILED DESCRIPTION

[0077] Embodiment 1:

[0078] To solve the technical problem of how to provide an unloading platform that can be respectively applied to the scene of a transport truck and a platform and the scene of a transport truck and the ground, the present application provides an unloading platform.

[0079] Specifically, referring to Figure 1 Or Figure 2 Or Figure 10 The unloading platform of the embodiment comprises a bottom frame 1, a middle frame 2, a top frame 3, a lifting mechanism 4, a first flap 5, a second flap 6, a first limiting assembly 7 and a second limiting assembly 8, and the first limiting assembly 7 and the second limiting assembly 8 respectively have a limiting position and a non-limiting position relative to the middle frame 2.

[0080] The unloading platform is arranged in a three-dimensional coordinate system for reference;

[0081] The bottom layer frame 1 is located below the middle layer frame 2 along the Z axis of the three-dimensional coordinate system, and the top layer frame 3 is located above the middle layer frame 2, and the lifting mechanism 4 is used to change the height of the top layer frame 3 relative to the middle layer frame 2;

[0082] The first turnover plate 5 and the second turnover plate 6 are respectively rotatably arranged at two ends of the top layer frame 3 along the X axis of the three-dimensional coordinate system, and the first limiting assembly 7 and the second limiting assembly 8 are respectively adjustably arranged at two ends of the middle layer frame 2, wherein the top layer frame 3 is provided with a unloading flat plate 31, the unloading flat plate 31 is located between the first turnover plate 5 and the second turnover plate 6, and the first turnover plate 5 and the second turnover plate 6 are located between the first limiting assembly 7 and the second limiting assembly 8;

[0083] The distance of the first limiting assembly 7 relative to the ground along the Z axis of the three-dimensional coordinate system is defined as a first height threshold, the first height threshold is limited to any value between a first lower limit value and a first upper limit value, the first lower limit value is specifically 40 centimeters, and the first upper limit value is specifically 160 centimeters, and the distance of the second limiting assembly 8 relative to the ground is defined as a second height threshold, the second height threshold is limited to any value between a second lower limit value and a second upper limit value, the second lower limit value is specifically 40 centimeters, and the second upper limit value is specifically 120 centimeters;

[0084] Under the condition of meeting the first height threshold, the first limiting assembly 7 is used to limit the angle of the first turnover plate 5 relative to the unloading flat plate 31, and under the condition of meeting the second height threshold, the second limiting assembly 8 is used to limit the angle of the second turnover plate 6 relative to the unloading flat plate 31.

[0085] In order to facilitate understanding, the application of the unloading platform of the embodiment to the scene of the transport truck and the platform is defined as a first scene, and the application of the unloading platform of the embodiment to the scene of the truck and the ground is defined as a second scene.

[0086] In the first scene, the unloading platform of the embodiment has two setting modes:

[0087] In the first setting mode, the unloading platform of the embodiment is first set at the platform, and then the transport truck is moved to the unloading platform of the embodiment;

[0088] In the second setting mode, the transport truck is first moved to the platform, and then the unloading platform of the embodiment is set between the transport truck and the platform.

[0089] In the first scene, when the unloading platform of the embodiment is located between the transport truck and the platform, the first limiting assembly 7 is limited to be close to the platform, and the second limiting assembly 8 is limited to be close to the transport truck;

[0090] Then, first, the position of the first limiting component 7 is adjusted so that it reaches the limiting position from the non-limiting position, and then the height of the first limiting component 7 is adjusted so that the height of the first limiting component 7 is flush or approximately flush with the height of the platform; specifically, in reality, the height of the platform is not uniform, and generally, the height of the platform is 1.2-1.6 meters, and the height of a small number of platforms is limited to 0.9 meters and 0.4 meters, etc.; therefore, in the present embodiment, the upper limit value of the first height threshold of the first limiting component 7 is configured to be 160 centimeters, and the lower limit value of the first height threshold of the first limiting component 7 is configured to be 40 centimeters; if the current height of the platform is 1.6 meters, then the height of the first limiting component 7 is adjusted to reach or approach 1.6 meters; or if the current height of the platform is 0.4 meters, then the height of the first limiting component 7 is adjusted to reach or approach 0.4 meters.

[0091] Similarly, first, the position of the second limiting component 8 is adjusted so that the second limiting component 8 reaches the limiting position from the non-limiting position, and then the height of the second limiting component 8 is adjusted so that the height of the second limiting component 8 is flush or approximately flush with the height of the cargo box of the transport truck to the ground (hereinafter referred to as the box-ground height); wherein the box-ground height of the transport truck is generally 0.8-1.2 meters, and the box-ground height of a small number of transport trucks or box trucks can reach 0.4 meters.

[0092] After adjusting the position and height of the first limiting component 7 and the position and height of the second limiting component 8 respectively, the top frame 3 is made to rise or fall relative to the middle frame 2 by the lifting mechanism 4, and at the same time, the middle frame 2 remains relatively stationary relative to the bottom frame 1.

[0093] During the rising action of the top frame 3, the first flap 5 is in an inclined state, and the first flap 5 is blocked by the first limiting component 7, so that the first flap 5 is generally in a movement mode along the Z-axis of the three-dimensional coordinate system, until the first flap 5 approaches or slightly exceeds the height of the current first limiting component 7, the first flap 5 rotates under the action of gravity, until the first flap 5 completely reaches or completely exceeds the height of the current first limiting component 7, the first flap 5 is generally in a horizontal state and points to the platform; wherein the first flap 5 is hinged to the unloading flat plate 31, so that the first flap 5 is rotatable relative to the unloading flat plate 31, or the first flap 5 is rotatable relative to the top frame 3;

[0094] In the process of the first lifting action of the top frame 3, the second flap 6 is in an inclined state and is blocked by the second limiting assembly 8, so that the second flap 6 is generally in a movement mode along the Z axis of the three-dimensional coordinate system until the second flap 6 approaches or slightly exceeds the height of the current second limiting assembly 8, the second flap 6 rotates under the action of gravity until the second flap 6 completely reaches or exceeds the height of the current second limiting assembly 8, and the second flap 6 is generally in a horizontal state and points to the transport truck; wherein the second flap 6 is hinged to the unloading flat plate 31, so that the second flap 6 forms a rotatable structure relative to the unloading flat plate 31 or the top frame 3.

[0095] In the first scenario, the height of the box ground and the height of the platform have the following three cases:

[0096] The first case: the height of the box ground is less than the height of the platform; in this case, the top frame 3 should first make a lifting action by the lifting mechanism 4 according to the height of the platform, and the first flap 5 is adjusted to be generally in a horizontal state and points to the platform, so that the workers and the ground ox (a simplified name of the ground ox forklift) can reach the unloading flat plate 31 through the platform and the first flap 5; then, the top frame 3 makes a descending action by the lifting mechanism 4, so that the second flap 6 is adjusted to be generally in a horizontal state and points to the transport truck, and then the workers and the ground ox can reach the transport truck through the second flap 6; when the workers and the ground ox move from the transport truck to the unloading flat plate 31, the top frame 3 makes a lifting action by the lifting mechanism 4, so that the first flap 5 is adjusted to be generally in a horizontal state and points to the platform again, and then the workers and the ground ox can move to the platform through the unloading flat plate 31 and the first flap 5.

[0097] The second case: the height of the box ground is equal to or approximately equal to the height of the platform; in this case, during the lifting action of the top frame 3 by the lifting mechanism 4, the time node at which the first flap 5 is adjusted to be generally in a horizontal state and points to the platform and the time node at which the second flap 6 is adjusted to be generally in a horizontal state and points to the transport truck can be considered to be the same or close; in other words, the first flap 5 and the second flap 6 can be approximately considered to be adjusted at the same time to match the current height of the box ground and the current height of the platform; at this time, the first flap 5, the unloading flat plate 31 and the second flap 6 form a bridge-shaped unloading channel, and the workers and the ground ox can freely move between the platform, the unloading channel and the transport truck;

[0098] The third case: the height of the box is greater than the height of the platform; in this case, the top frame 3 should first be raised by the lifting mechanism 4 according to the height of the platform, and the first flap 5 is adjusted to be substantially horizontal and points to the platform, so that the workers and the ground cow (a simple name for the ground cow forklift) can reach the unloading platform 31 through the platform and the first flap 5; then, the top frame 3 is raised again by the lifting mechanism 4, so that the second flap 6 is adjusted to be substantially horizontal and points to the transport truck, so that the workers and the ground cow can reach the transport truck through the second flap 6; when the workers and the ground cow move from the transport truck to the unloading platform 31, the lifting mechanism 4 makes the top frame 3 lower, so that the first flap 5 is adjusted to be substantially horizontal and points to the platform again, so that the workers and the ground cow can move to the platform through the unloading platform 31 and the first flap 5.

[0099] In the second scenario, the unloading platform of the present embodiment should be pushed by the workers to the position of the transport truck, and the second flap 6 and the second limiting assembly 8 face the box of the transport truck;

[0100] Then, first, adjust the position of the second limiting assembly 8 so that it reaches the limiting position from the non-limiting position, and then adjust the height of the second limiting assembly 8 so that the height of the second limiting assembly 8 is flush or approximately flush with the height of the box of the transport truck;

[0101] And, keep or adjust the first limiting assembly 7 so that the first limiting assembly 7 is limited in the non-limiting position, in other words, in the second scenario, the first limiting assembly 7 is not used to limit the first flap 5;

[0102] After adjusting the position and height of the first limiting assembly 7 and the position of the second limiting assembly 8 respectively, since the first flap 5 is not blocked by the first limiting assembly 7, the first flap 5 is turned to the "ground pointing direction" under the action of gravity, and the edge of the first flap 5 contacts the ground and forms an inclined ramp relative to the ground; At this time, the workers and the ground cow can reach the unloading platform 31 through the first flap 5; then, the top frame 3 is raised by the lifting mechanism 4, so that the second flap 6 is adjusted to be substantially horizontal and points to the transport truck, so that the workers and the ground cow can reach the transport truck through the second flap 6, and at this time, a gap is formed between the first flap 5 and the ground; When the workers and the ground cow move from the transport truck to the unloading platform 31, the lifting mechanism 4 makes the top frame 3 lower, so that the first flap 5 contacts the ground again and forms an inclined ramp relative to the ground; At this time, the workers and the ground cow can move to the ground through the second flap 6.

[0103] It should be understood that the unloading platform of the embodiment includes universal wheels and rollers, which will be described later.

[0104] It should be understood that the first flap 5 and the second flap 6 are respectively hinged to the top layer frame 3, and the first flap 5 and the second flap 6 are respectively connected to the top layer frame 3 by iron chains or other rope-shaped components or chain-shaped components (not shown in the figure) for manual operation of the first flap 5 and the second flap 6, which is known to those skilled in the art.

[0105] It should be understood that the specific structure of the lifting mechanism 4 in the embodiment is different from the structure and use effect of the lifting mechanism 4 of the unloading platform in the prior art, which will be described later.

[0106] It should be understood that the first limiting component 7 in the embodiment can limit the angle of the first flap 5 relative to the unloading platform 31 within its first height threshold range, and is suitable for more height scenarios of the platform and the truck; similarly, the second limiting component 8 in the embodiment can limit the angle of the second flap 6 relative to the unloading platform 31 within its second height threshold range, and is suitable for more height scenarios of the truck and the platform.

[0107] The unloading platform provided by the embodiment at least by setting the first limiting component 7 which can adjust the height and change the limiting position and the non-limiting position, is used to limit or not limit the position, height and angle relative to the ground of the first flap 5, by setting the second limiting component 8 which can adjust the height and change the limiting position and the non-limiting position, is used to limit or not limit the position, height and angle relative to the ground of the second flap 6, so that the unloading platform can be suitable for the scenarios of the transport truck and the platform, and the scenarios of the transport truck and the ground.

[0108] Further, in order to facilitate those skilled in the art to understand, the embodiment provides a preferred first limiting component 7, which is as follows:

[0109] Referring to Figure 3 The unloading platform of the embodiment, the first limiting component 7 includes a first adjusting rod 71, a first limiter 72 and a second limiter 73;

[0110] The extension direction of the first adjusting rod 71 is parallel to the Z axis of the three-dimensional coordinate system, and the first adjusting rod 71 is fixedly or detachably arranged on the middle layer frame 2;

[0111] The first limiter 72 comprises a first sliding sleeve 721, a first locking bolt 722 and a first pulley 723. The first sliding sleeve 721 is sleeved on the first adjusting rod 71 and is configured as a sliding pair and a rotating pair relative to the first adjusting rod 71. The first locking bolt 722 is used for adjusting looseness or locking of the first sliding sleeve 721 relative to the first adjusting rod 71. The first pulley 723 is arranged on the first sliding sleeve 721, wherein a circumferential surface of the first pulley 723 is used to be contacted by the first flap 5.

[0112] The second limiter 73 comprises two second sliding sleeves 731, a third sliding sleeve 732, a first limiting sleeve 733, a first limiting rod 734, two second locking bolts 735, a third locking bolt 736 and three second pulleys 737.

[0113] The two second sliding sleeves 731 and the third sliding sleeve 732 are respectively sleeved on the first adjusting rod 71 and are respectively configured as a sliding pair and a rotating pair relative to the first adjusting rod 71.

[0114] Two ends of the first limiting sleeve 733 are respectively fixedly connected to one of the second sliding sleeves 731. One end of the first limiting rod 734 is fixedly connected to the third sliding sleeve 732. Along a negative direction of a Z-axis of the three-dimensional coordinate system, the other end of the first limiting rod 734 is inserted into the first limiting sleeve 733. A total length of the first limiting rod 734 and the first limiting sleeve 733 is greater than or equal to twice a length of the first flap 5. A length of the first limiting sleeve 733 is less than or equal to the length of the first flap 5.

[0115] The two second sliding sleeves 731 and the third sliding sleeve 732 are respectively provided with one of the second pulleys 737. The two second sliding sleeves 731 and the third sliding sleeve 732 are respectively adjusted to be loose or locked relative to the first adjusting rod 71 by one of the second locking bolts 735. The first limiting sleeve 733 is provided with a first limiting surface which is tangent to a circumferential surface of the second pulley 737 located at one of the second sliding sleeves 731. The first limiting rod 734 is provided with a second limiting surface which is tangent to a circumferential surface of the second pulley 737 located at the third sliding sleeve 732. The circumferential surfaces of the three second pulleys 737, the first limiting surface and the second limiting surface are respectively used to be contacted by the first flap 5.

[0116] The first height threshold value comprises a first intermediate value and a second intermediate value. The first lower limit value, the first intermediate value, the second intermediate value and the first upper limit value are arranged in an increasing manner.

[0117] A difference between the first intermediate value and the first lower limit value is equal to or less than the length of the first flap 5. Between the first lower limit value and the first intermediate value, the first limiter 72 is used to limit an angle of the first flap 5 relative to the unloading flat plate 31.

[0118] The difference between the second intermediate value and the first intermediate value is equal to or less than the length of the first flap 5, and the difference between the first upper limit value and the second intermediate value is equal to or less than the length of the first flap 5. The second limiter 73 is used to limit the angle of the first flap 5 relative to the unloading flat plate 31 between the first intermediate value and the second intermediate value, and between the first upper limit value and the first intermediate value.

[0119] In actual use of the first limiting assembly 7, if the height of the platform matches the first intermediate value and the first lower limit value, including: the height of the platform is the same as the first intermediate value, or the height of the platform is the same as the first lower limit value, or the height of the platform is between the first intermediate value and the first lower limit value, then the second limiter 73 is adjusted to the non-limiting position, and the first limiter 72 is adjusted to the limiting position; the height of the first limiter 72 is adjusted to be flush with the height of the platform, specifically, the top end of the first pulley 723 of the first limiter 72 is flush with the height of the platform;

[0120] When the top frame 3 and the middle frame 2 are in the initial state (the state with the smallest distance between the top frame 3 and the middle frame 2), the first flap 5 is blocked by the first limiter 72 in an obtuse angle state relative to the unloading flat plate 31, so that the current first flap 5 cannot change the angle relative to the unloading flat plate 31 (i.e. cannot be flipped); during the process of the top frame 3 rising relative to the bottom frame 1 and reaching the height corresponding to the first intermediate value, the first flap 5 is blocked by the first limiter 72, but as the height of the first flap 5 changes, the angle of the first flap 5 relative to the unloading flat plate 31 changes until the overall profile of the first flap 5 reaches the top end of the first pulley 723, so that the first flap 5 changes from the obtuse angle state to the flat angle state relative to the unloading flat plate 31. At this time, the top frame 3 and the middle frame 2 are in the working state; if the top frame 3 continues to rise at this time, the first flap 5 changes from the flat angle state to the acute angle state relative to the unloading flat plate 31.

[0121] Conversely, during the process of the top frame 3 and the middle frame 2 changing from the working state to the initial state, i.e. the top frame 3 is in the process of descending, the first flap 5 is blocked by the first pulley 723, so that the first flap 5 changes from the flat angle state to the obtuse angle state relative to the unloading flat plate 31. As the top frame 3 continues to descend, the angle of the first flap 5 relative to the unloading flat plate 31 gradually decreases until the top frame 3 and the middle frame 2 return to the initial state.

[0122] Similarly, in the actual use of the first limiting assembly 7, if the height of the platform matches the second intermediate value and the first upper limit value, including: the height of the platform is the same as the second intermediate value, or the height of the platform is the same as the first upper limit value, or the height of the platform is between the first intermediate value and the second intermediate value, or the height of the platform is between the second intermediate value and the first upper limit value, then the first limiter 72 is adjusted to the non-limiting position, and the second limiter 73 is adjusted to the limiting position; the height of the second limiter 73 is adjusted to be flush with the height of the platform, specifically, the top end of the second pulley 737 of the third sliding sleeve 732 of the second limiter 73 is flush with the height of the platform; at the same time, the bottom end of the first limiting sleeve 733 of the first limiter 72 is adjusted to be between the first intermediate value and the first lower limit value, and the top end of the first limiting sleeve 733 is limited between the first intermediate value and the second intermediate value;

[0123] When the top frame 3 and the middle frame 2 are in the initial state, the first flap 5 is blocked by the second limiter 73 relative to the unloading platform 31 in an obtuse angle state, specifically, the current first flap 5 is blocked by the second limiting sleeve, so that the current first flap 5 cannot change the angle relative to the unloading platform 31; in the process of the top frame 3 rising relative to the bottom frame 1 and reaching the height corresponding to the second intermediate value or the first upper limit value, the first flap 5 is blocked by the second limiter 73, specifically, the first flap 5 is sequentially blocked by the first limiting sleeve 733, the second pulley 737 at the top end of the first limiting sleeve 733, the first limiting rod 734 and the second pulley 737 on the third sliding sleeve 732 in the rising direction, but as the height of the first flap 5 changes constantly, the angle of the first flap 5 relative to the unloading platform 31 changes constantly, until the overall profile of the first flap 5 reaches the top end of the second pulley 737 on the third sliding sleeve 732, so that the first flap 5 changes from an obtuse angle state to a straight angle state relative to the unloading platform 31, at this time, the top frame 3 and the middle frame 2 are in a working state; if the top frame 3 continues to rise at this time, the first flap 5 changes from a straight angle state to a right angle state relative to the unloading platform 31;

[0124] Conversely, in the process of the top frame 3 and the middle frame 2 changing from the working state to the initial state, that is, the top frame 3 makes a descending action, the first flap 5 is blocked by the second pulley 737 on the third sliding sleeve 732, so that the first flap 5 changes from a straight angle state to an obtuse angle state relative to the unloading platform 31, as the top frame 3 continues to descend, the angle of the first flap 5 relative to the unloading platform 31 gradually decreases, until the top frame 3 and the middle frame 2 return to the initial state.

[0125] It should be understood that when the height of the platform matches the first upper limit value or is between the first upper limit value and the second intermediate value, the top end of the second pulley 737 of the third sliding sleeve 732 should be set at the position corresponding to the first upper limit value or between the first upper limit value and the second intermediate value, and at this time, the top end of the first limiting sleeve 733 is limited between the first intermediate value and the second intermediate value, so that the bottom end of the first limiting sleeve 733 is located between the first intermediate value and the first lower limit value, so that the first flap 5 in the initial state can be blocked by the first limiting sleeve 733.

[0126] It should be understood that when the height of the platform matches the second intermediate value or is between the second intermediate value and the first intermediate value, the top end of the second pulley 737 of the third sliding sleeve 732 should be set at the position corresponding to the second intermediate value or between the second intermediate value and the first intermediate value, and at this time, the top end of the first limiting sleeve 733 is limited between the first intermediate value and the second intermediate value, so that the bottom end of the first limiting sleeve 733 is located between the first intermediate value and the first lower limit value, so that the first flap 5 in the initial state can be blocked by the first limiting sleeve 733.

[0127] It should be understood that the first limiter 72 switches between the limiting position and the non-limiting position through the first locking bolt 722 and the first sliding sleeve 721; when the first locking bolt 722 adjusts the first sliding sleeve 721 and the first adjusting rod 71 to be loose, the first sliding sleeve 721 can rotate relative to the first adjusting rod 71, and vice versa, when the first locking bolt 722 adjusts the first sliding sleeve 721 and the first adjusting rod 71 to be locked, the first sliding sleeve 721 cannot rotate relative to the first adjusting rod 71; similarly, the second limiter 73 switches between the limiting position and the non-limiting position through the third locking bolt 736, the two second sliding sleeves 731 and the third sliding sleeve 732, and the principle is the same as that of the first sliding sleeve 721 and the first locking bolt 722 described above, which will not be repeated here.

[0128] It should be understood that the first position limiter 72 is adjusted to slide or be stationary relative to the first adjusting rod 71 by the first locking bolt 722 and the first sliding sleeve 721; when the first locking bolt 722 adjusts the first sliding sleeve 721 and the first adjusting rod 71 to be loose, the first sliding sleeve 721 can slide relative to the first adjusting rod 71, so that the first position limiter 72 as a whole can reach any position between the first lower limit value and the first intermediate value, and then the first locking bolt 722 is used to lock the first sliding sleeve 721 and the first adjusting rod 71; similarly, the second position limiter 73 is adjusted to slide or be stationary relative to the first adjusting rod 71 by the two second sliding sleeves 731, the third sliding sleeve 732 and the two second locking bolts 735, and the principle is the same as that of the first locking bolt 722 and the first sliding sleeve 721, which will not be described here.

[0129] Further, in order to facilitate those skilled in the art to understand, the embodiment provides a preferred second position limiting assembly 8, which is specifically as follows:

[0130] Referring to Figure 4 , the unloading platform of the embodiment, the second position limiting assembly 8 comprises a second adjusting rod 81, a third position limiter 82 and a fourth position limiter 83;

[0131] The extension direction of the second adjusting rod 81 is parallel to the Z axis of the three-dimensional coordinate system, and the second adjusting rod 81 is fixedly or detachably arranged on the middle layer frame 2;

[0132] The third position limiter 82 comprises a fourth sliding sleeve 821, a fifth sliding sleeve 822, two fourth locking bolts 823, two third pulleys 825 and a first limiting ruler 826;

[0133] The fourth sliding sleeve 821 and the fifth sliding sleeve 822 are respectively sleeved on the second adjusting rod 81, and the fourth sliding sleeve 821 and the fifth sliding sleeve 822 are respectively configured as a sliding pair and a rotating pair relative to the second adjusting rod 81;

[0134] One end of the first limiting ruler 826 is connected to the fourth sliding sleeve 821, the connection position of the first limiting ruler 826 and the fifth sliding sleeve 822 is between the two ends of the first limiting ruler 826, the fifth sliding sleeve 822 is located below the fourth sliding sleeve 821, and the length of the first limiting ruler 826 is greater than or equal to the length of the second flap 6;

[0135] The fourth sliding sleeve 821 and the fifth sliding sleeve 822 are respectively adjusted to be loose or locked relative to the second adjusting rod 81 by one of the fourth locking bolts 823, and the fourth sliding sleeve 821 and the fifth sliding sleeve 822 are respectively provided with one of the third pulleys 825, wherein the first limiting ruler 826 has a third limiting surface, the third limiting surface is tangent to the circumferential surfaces of the two third pulleys 825, and the third limiting surface and the circumferential surfaces of the two third pulleys 825 are respectively used to be contacted by the second flap 6;

[0136] The fourth limiter 83 comprises a sixth sleeve 831, a fifth locking bolt 832 and a fourth pulley 833, the sixth sleeve 831 is sleeved on the second adjusting rod 81, the sixth sleeve 831 is configured as a sliding pair and a rotating pair relative to the second adjusting rod 81, the fifth locking bolt 832 is used for adjusting the looseness or locking of the sixth sleeve 831 relative to the second adjusting rod 81, and the fourth pulley 833 is arranged on the sixth sleeve 831, wherein the circumferential surface of the fourth pulley 833 is used to be contacted by the second flap 6;

[0137] The second height threshold comprises a third intermediate value, a second lower limit value, the third intermediate value and the second upper limit value are arranged in an increasing manner;

[0138] The difference between the third intermediate value and the second lower limit value is equal to or less than the length of the second flap 6, between the second lower limit value and the third intermediate value, the fourth limiter 83 is used to limit the angle of the second flap 6 relative to the unloading platform 31;

[0139] The difference between the second upper limit value and the third intermediate value is equal to or less than the length of the second flap 6, between the second upper limit value and the third intermediate value, the third limiter 82 is used to limit the angle of the second flap 6 relative to the unloading platform 31.

[0140] The specific role and principle of the second limiting assembly 8 are the same as or similar to those of the aforementioned first limiting assembly 7, the difference is that the third limiter 82 of the second limiting assembly 8 only limits the angle of the second flap 6 relative to the unloading platform 31 through the first limiting ruler 826 and the third pulley 825 located in the fourth sleeve 821, and the second height threshold of the second limiting assembly 8 is different from the first height threshold of the aforementioned first limiting assembly 7, and the rest will not be repeated here.

[0141] Further, the length of the first flap 5 and the length of the second flap 6 of the unloading platform of the embodiment are 40 centimeters respectively;

[0142] The first intermediate value is specifically 80 centimeters, the second intermediate value is specifically 120 centimeters, and the third intermediate value is specifically 80 centimeters.

[0143] Under the condition that the first upper limit value is 160 centimeters and the first lower limit value is 40 centimeters, the difference between any adjacent values in the first lower limit value, the first intermediate value, the second intermediate value and the first upper limit value is 40 centimeters respectively, which makes the first flap 5 with a length of 40 centimeters can be blocked by the first limiting assembly 7 after being adjusted between the height of 40 centimeters to 160 centimeters;

[0144] In the condition that the second upper limit value is 120 cm and the second lower limit value is 40 cm, the difference between any adjacent values among the second lower limit value, the third intermediate value and the second upper limit value is 40 cm respectively, which makes the second flap 6 with a length of 40 cm be blocked by the second limiting assembly 8 after being adjusted, between the height of 40 cm and 120 cm.

[0145] Further, in the foregoing scheme, when the transport truck arrives at the platform first, and the unloading platform of the embodiment is pushed to the position between the transport truck and the platform, it is possible that the length of the second flap 6 is less than the distance between the current transport truck and the unloading platform 31, resulting in that the second flap 6 cannot contact the container of the transport truck after being flipped; and it is possible that the length of the first flap 5 is less than the distance between the current platform and the unloading platform 31, resulting in that the first flap 5 cannot contact the platform after being flipped.

[0146] In the embodiment, in order to solve the above problems, a function for adjusting the position of the top frame 3 relative to the truck or the platform is added.

[0147] Specifically, referring to Figure 5 The unloading platform of the embodiment is provided with a horizontal hydraulic cylinder 9 and a plurality of rollers 10;

[0148] The axis of each roller 10 is parallel to the Y axis of the three-dimensional coordinate system, each roller 10 is rotatably connected to the bottom frame 1, and all the rollers 10 are tangent to the same horizontal movement plane;

[0149] The horizontal hydraulic cylinder 9 has a horizontal cylinder barrel 91, a horizontal piston and a horizontal hydraulic rod 93, both ends of the horizontal hydraulic rod 93 are located outside the horizontal cylinder barrel 91, and the intersection of the horizontal hydraulic rod 93 and the horizontal piston is located inside the horizontal cylinder barrel 91, wherein the length direction of the horizontal hydraulic rod 93 and the length direction of the horizontal cylinder barrel 91 are parallel to the X axis of the three-dimensional coordinate system, the horizontal cylinder barrel 91 is fixedly connected to the bottom frame 1, and both ends of the horizontal hydraulic rod 93 are detachably connected to the middle frame 2.

[0150] The bottom of the middle frame 2 contacts the plurality of rollers 10, and the middle frame 2 and the bottom frame 1 are spaced apart by the plurality of rollers 10 to form a gap, so as to reduce the friction between the middle frame 2 and the bottom frame 1;

[0151] The horizontal hydraulic cylinder 9 is used to drive the middle layer frame 2 to produce bidirectional movement along the X-axis direction of the three-dimensional coordinate system relative to the bottom layer frame 1; for example, if the platform and the first flap 5 are located at the positive direction of the X-axis of the three-dimensional coordinate system, then the horizontal hydraulic cylinder 9 can drive the middle layer frame 2 to produce movement along the positive direction of the X-axis of the three-dimensional coordinate system; similarly, if the truck and the second flap 6 are located at the negative direction of the X-axis of the three-dimensional coordinate system, then the horizontal hydraulic cylinder 9 can drive the middle layer frame 2 to produce movement along the negative direction of the X-axis of the three-dimensional coordinate system.

[0152] Since the lifting mechanism 4, the first limiting component 7 and the second limiting component 8 are respectively arranged on the middle layer frame 2, and the top layer frame 3 provided with the first flap 5 and the second flap 6 is arranged on the middle layer frame 2, in the process of the movement of the middle layer frame 2 relative to the bottom layer frame 1, the lifting mechanism 4, the first limiting component 7, the second limiting component 8, the first flap 5, the second flap 6 and the top layer frame 3 are in a synchronous state and move with the middle layer frame 2, thereby avoiding deformation of the lifting mechanism 4, the first limiting component 7, the second limiting component 8, the first flap 5, the second flap 6 and the top layer frame 3 relative to the middle layer frame 2 or avoiding resistance to the movement of the middle layer frame 2.

[0153] In the process of the actual movement of the middle layer frame 2 driven by the horizontal hydraulic cylinder 9, the horizontal cylinder barrel 91 remains stationary relative to the bottom layer frame 1, and the horizontal hydraulic rod 93 and the horizontal piston are in a moving state relative to the bottom layer frame 1; it should be understood that the horizontal hydraulic cylinder 9 of the embodiment is a double-end hydraulic cylinder, and both ends of the horizontal hydraulic rod 93 thereof are located outside the horizontal cylinder barrel 91; the structure and principle of the double-end hydraulic cylinder are well known to those skilled in the art, and will not be described here; the connection structure of the horizontal cylinder barrel 91 and the bottom layer frame 1 is configured in a detachable connection mode, including but not limited to flange connection, threaded connection, etc.; the connection mode of the horizontal hydraulic rod 93 and the middle layer frame 2 is configured in a detachable connection mode, including but not limited to bolt connection using a positioning seat, the positioning seat being fixedly arranged at the end of the horizontal hydraulic rod 93 and being bolted to the middle layer frame 2.

[0154] Further, on the basis of the foregoing scheme, preferably, referring to Figure 6 to Figure 8 , the lifting mechanism 4 comprises four positioning columns 41, four vertical hydraulic cylinders 42 and four pushing components 43, each of the pushing components 43 is provided with a sprocket 44 and a chain 45;

[0155] The extension direction of each of the positioning columns 41 is parallel to the Z-axis of the three-dimensional coordinate system, and each of the positioning columns 41 is arranged on the middle layer frame 2;

[0156] The vertical hydraulic cylinder 42 comprises a vertical hydraulic rod 421, a vertical piston and a vertical cylinder barrel 422, both ends of the vertical hydraulic rod 421 are located outside the vertical cylinder barrel 422 respectively, the intersection of the vertical hydraulic rod 421 and the vertical piston is located inside the vertical cylinder barrel 422, wherein the length direction of the vertical hydraulic rod 421 and the length direction of the vertical cylinder barrel 422 are parallel to the Z axis of the three-dimensional coordinate system respectively, and the vertical hydraulic rod 421 is fixedly connected with the middle layer frame 2;

[0157] The vertical cylinder barrel 422 is used to push the jacking part 43 along the Z axis of the three-dimensional coordinate system;

[0158] The sprocket 44 and the chain 45 constitute a transmission pair, wherein one end of the chain 45 is connected to the middle layer frame 2, and the other end of the chain 45 is connected to the top layer frame 3.

[0159] The lifting mechanism 4 is provided with four vertical hydraulic cylinders 42, on the one hand, the lifting power of the unloading platform of the embodiment is improved through the four vertical hydraulic cylinders 42 to meet the lifting of relatively heavy load; on the other hand, the four vertical hydraulic cylinders 42 can uniformly apply driving force to the top layer frame 3, so that the top layer frame 3 can make lifting action relatively stably; on the other hand, the four vertical hydraulic cylinders 42 can better bear the weight of the top layer frame 3, improve the safety and reliability of the unloading platform of the embodiment.

[0160] In addition, the lifting mechanism 4 is provided with four jacking parts 43, one of the purposes is to drive the sprocket 44 and the chain 45 through the vertical cylinder barrel 422 of the vertical hydraulic cylinder 42, and the other purpose is to enable the vertical cylinder barrel 422 to apply driving force to other parts (see the following description);

[0161] In the embodiment, the vertical cylinder barrel 422 is the power source of the sprocket 44 and the chain 45, the vertical hydraulic rod 421 remains stationary relative to the middle layer frame 2, so that the vertical hydraulic rod 421 becomes one of the guide parts; the vertical cylinder barrel 422 has three positions relative to the vertical hydraulic rod 421, which are initial position, lower limit position and upper limit position, wherein along the Z axis of the three-dimensional coordinate system, the upper limit position is located at or close to the top end of the vertical hydraulic rod 421, the lower limit position is located at the bottom end of the vertical hydraulic rod 421, and the initial position is located between the upper limit position and the lower limit position and close to the lower limit position;

[0162] In the process of driving the top frame 3 to make the lifting action, the vertical cylinder 422 moves from the initial position to the upper limit position, the vertical cylinder 422 contacts and pushes one of the pushing parts 43, so that the pushing part 43 drives the chain wheel 44 to make the lifting action, at this time, the connecting position of the chain 45 and the top frame 3 makes the lifting action, so that the top frame 3 makes the lifting action, and the connecting position of the chain 45 and the middle frame 2 remains stationary.

[0163] In the process of making the lifting action of the top frame 3, the vertical cylinder 422 moves along the direction from the upper limit position to the initial position, and the pushing part 43 and the top frame 3 naturally fall under the action of gravity, until the vertical cylinder 422 reaches the initial position.

[0164] Further, in the foregoing scheme, when the vertical cylinder 422 moves from the initial position to the lower limit position, in order to avoid the chain 45 from loosening relative to the chain wheel 44 due to the descending action of the pushing part 43 under the action of gravity, the following technical scheme is preferably adopted.

[0165] Referring to Figure 6 The lifting mechanism 4 of the unloading platform further comprises four stop parts 46.

[0166] Each positioning column 41 is provided with a stop part 46, wherein, along the Z axis of the three-dimensional coordinate system, the stop part 46 is located below the pushing part 43, and the stop part 46 and the middle frame 2 form a spacing.

[0167] When the vertical cylinder 422 is located at the initial position, the vertical cylinder 422 and the stop part 46 jointly support one of the pushing parts 43, avoiding the descending action of the pushing part 43; when the vertical cylinder 422 moves from the initial position to the lower limit position, the vertical cylinder 422 and the pushing part 43 form a gap or a spacing, and at the same time, the stop part 46 independently supports the pushing part 43, avoiding the descending action of the pushing part 43, thereby avoiding the loosening phenomenon of the chain wheel 44 relative to the chain 45.

[0168] Further, in the foregoing scheme, in order to reduce the friction between the pushing part 43 and the positioning column 41, the following technical scheme is preferably adopted.

[0169] Referring to Figure 6 Or Figure 8 Each pushing part 43 of the unloading platform is provided with a first positioning wheel 47 and a second positioning wheel 48, and the first positioning wheel 47 and the second positioning wheel 48 are rotatably connected to the pushing part 43.

[0170] The positioning column 41 has a first side plate 411, a second side plate 412 and a connecting plate 413, the first side plate 411 and the second side plate 412 are parallel to each other, the connecting plate 413 is located between the first side plate 411 and the second side plate 412, and the first side plate 411, the connecting plate 413 and the second side plate 412 form an I-shaped steel structure;

[0171] The first positioning wheel 47 is limited to contact the first side plate 411, and the second positioning wheel 48 is limited to contact the second side plate 412.

[0172] The first positioning wheel 47 contacts the first side plate 411 of the positioning column 41, and the second positioning wheel 48 contacts the second side plate 412 of the positioning column 41. In the process of the pushing component 43 being driven by the vertical cylinder 422 to make an upward action and being subjected to gravity to make a downward action, the first positioning wheel 47 rotates relative to the first side plate 411, and the second positioning wheel 48 rotates relative to the second side plate 412.

[0173] Further, referring to Figure 9 The unloading platform also comprises four first universal wheels 11 and four supporting feet 12, each supporting foot 12 is welded to one corner of the bottom frame 1, and each first universal wheel 11 is connected to the bottom frame 1 and one of the supporting feet 12.

[0174] The four first universal wheels 11 reduce the steering amplitude of the unloading platform, and specifically, the four universal wheels can rotate in the horizontal direction (the XY plane direction of the three-dimensional coordinate system), and the rotation of the four universal wheels replaces the steering action of the unloading platform as a whole relative to a part of the ground, thereby reducing the steering amplitude of the unloading platform as a whole relative to the ground.

[0175] In the scenario that the transport truck first arrives at the platform, if the length direction of the transport truck is limited to the X-axis direction of the three-dimensional coordinate system, then the direction of the access passage of the position between the transport truck and the platform is the Y-axis direction, at this time, the worker can push the unloading platform of the embodiment along the Y-axis direction of the three-dimensional coordinate system so that the unloading platform directly reaches the position between the transport truck and the platform; or the worker first pushes the unloading platform along the X-axis direction of the three-dimensional coordinate system to reach the side of the position between the transport truck and the platform, at this time, the advancing direction of the four first universal wheels 11 is limited to the X-axis of the three-dimensional coordinate system, then the worker pushes the unloading platform along the Y-axis direction again, in the process, the advancing direction of the four first universal wheels 11 is changed from the X-axis of the three-dimensional coordinate system to the Y-axis of the three-dimensional coordinate system through the rotation of the four first universal wheels 11, and then the worker can push the unloading platform to the position between the transport truck and the platform.

[0176] In the embodiment, the structure of the four first supporting legs 12 can adopt the structure of the supporting leg 12 in the prior art, as long as the first supporting leg 12 can adjust the spacing by manual mode and can bear the weight, which will not be described here.

[0177] Further, in the foregoing scheme, when the unloading platform of the embodiment has been located at the position between the transport truck and the platform, and it is necessary to adjust the spacing of the unloading platform relative to the transport truck or to adjust the spacing of the unloading platform relative to the platform, since the current advancing direction of the four first universal wheels 11 is the Y-axis direction, and since the spacing of the unloading platform relative to the transport truck and the platform is relatively small, it is easy for the worker to push the unloading platform along the X-axis direction to cause the unloading platform to produce a turning action relative to the ground, which causes the unloading platform to bump into the platform or the truck; in order to solve this problem, the following technical scheme is preferably adopted.

[0178] Referring to Figure 6 Or Figure 9 , the unloading platform of the embodiment further comprises four second rollers 13, four telescopic assemblies 14, a plurality of load-bearing plates 15, and a plurality of load-bearing wheels 16;

[0179] Each telescopic assembly 14 comprises a spring 141, a positioning sleeve 142, and a transmission rod 143, the positioning sleeve 142 is welded to the middle layer frame 2, the length direction of the positioning sleeve 142 is parallel to the Z-axis of the three-dimensional coordinate system, and the transmission rod 143 and the positioning sleeve 142 form a sleeve structure, wherein along the Z-axis of the three-dimensional coordinate system, the transmission rod 143 has a top end that can be exposed on the upper part of the middle layer frame 2 and a bottom end that can be exposed on the lower part of the middle layer frame 2, the top end of the transmission rod 143 is provided with a stepped portion, the diameter of the stepped portion is greater than the diameter of the transmission rod 143, and the bottom end of the transmission rod 143 is provided with one of the second rollers 13;

[0180] Each vertical cylinder 422 is provided with a driving component 17, which is welded to the vertical cylinder 422, wherein the driving component 17 is used to drive the transmission rod 143 along the direction from the top end to the bottom end;

[0181] The middle layer frame 2 is provided with two load-bearing rails 18, each of which is parallel to the X-axis of the three-dimensional coordinate system, and the two load-bearing rails 18 are separated by the bottom layer frame 1 and parallel to each other;

[0182] The plurality of load-bearing plates 15 are divided into two groups, and the first group of load-bearing plates 15 and the second group of load-bearing plates 15 are separated by the bottom layer frame 1, one end of each load-bearing plate 15 is fixedly or detachably connected to the bottom layer frame 1, and the other end of each load-bearing plate 15 is rotatably provided with one of the load-bearing wheels 16, wherein each load-bearing wheel 16 contacts one of the load-bearing rails 18 along the direction from the top end to the bottom end.

[0183] The advancing direction of the four second rollers 13 is consistent with the direction formed by the first turning plate 5, the unloading platform 31, and the second turning plate 6; for example, if the direction formed by the first turning plate 5, the unloading platform, and the second turning plate 6 is configured as the X-axis direction of the three-dimensional coordinate system, then the advancing direction of the four second rollers 13 is limited to the X-axis direction.

[0184] In the foregoing scheme, it has been proposed that when the unloading platform reaches the position between the transport truck and the platform under the condition that the transport truck reaches the platform, the advancing direction of the four first universal wheels 11 is the Y-axis direction of the three-dimensional coordinate system, at this time, if the staff needs to push the unloading platform along the X-axis of the three-dimensional coordinate system, the staff can operate the vertical cylinder 422 to make the vertical cylinder 422 make a descending action along the initial position to the lower limit position;

[0185] During the descending action of the vertical cylinder 422 along the initial position to the lower limit position, the driving component 17 on the vertical cylinder 422 makes a descending action with the vertical cylinder 422, and each driving component 17 contacts the transmission rod 143 of one of the telescopic assemblies 14, so that the transmission rod 143 makes a descending action;

[0186] During the descending action of the transmission rod 143, the transmission rod 143 forms a sliding pair with the positioning sleeve 142, and the transmission rod 143 extrudes the spring 141 through the step portion and the middle layer frame 2, so that the spring 141 is compressed and shortened in length by itself, and at the same time, the transmission rod 143 drives one of the second rollers 13, so that the second roller 13 changes from the state of generating a distance relative to the ground to the state of contacting the ground;

[0187] When the second roller 13 contacts the ground, the second roller 13 receives a reaction force from the ground, which is transmitted to the vertical cylinder 422 through the second roller 13, the transmission rod 143 and the driving part 17; at this time, the vertical cylinder 422 still makes a downward action relative to the vertical hydraulic rod 421, but the top frame 3, the middle frame 2 and the bottom frame 1 make a rising action relative to the vertical hydraulic cylinder 42, wherein the middle frame 2 and the bottom frame 1 are connected along the Z-axis direction of the three-dimensional coordinate system through the plurality of bearing plates 15, the plurality of bearing wheels 16 and the two bearing rails 18, so that in the process of the middle frame 2 making a rising action, the middle frame 2 applies a rising force to the plurality of bearing wheels 16 through the two bearing rails 18, and then the plurality of bearing wheels 16 apply a rising force to the bottom frame 1 through the plurality of bearing plates 15, until the bottom frame 1 has a gap with the ground.

[0188] Conversely, after the staff completes the pushing action along the X-axis of the three-dimensional coordinate system by using the four second rollers 13, the staff controls the vertical cylinder 422 to make a movement along the direction from the lower limit position to the initial position; wherein under the action of gravity, the top frame 3, the middle frame 2 and the bottom frame 1 simultaneously make a downward action until the bottom frame 1 contacts the ground.

[0189] After the bottom frame 1 contacts the ground, the vertical cylinder 422 further rises, at this time, under the action of the elastic force of the spring 141, the spring 141 drives the transmission rod 143 through the stepped part, so that the transmission rod 143 makes a rising action, and at the same time, the transmission rod 143 drives the second roller 13 to make a rising action, until the vertical cylinder 422 moves to the initial position, and the second roller 13 re-generates a gap relative to the ground.

[0190] In the above manner, on the one hand, the four second rollers 13 are driven by the four vertical cylinders 422 and the four telescopic assemblies 14, so that the four second rollers 13 can change the gap relative to the ground without interfering with each other relative to the four first rollers, thereby realizing the function of changing the direction of the unloading platform by the four second rollers 13, and reducing or avoiding the unloading platform from bumping into the transport slot or the platform, on the other hand, when the four second rollers 13 contact the ground and the middle frame 2 and the bottom frame 1 have a rising trend, the plurality of bearing plates 15, the plurality of bearing wheels 16 and the two bearing rails 18 can make the middle frame 2 and the bottom frame 1 realize a synchronous rising action, thereby avoiding the horizontal hydraulic rod 93 of the horizontal hydraulic cylinder 9 from being bent by the middle frame 2, and further improving the reliability of the unloading platform of the embodiment.

[0191] It should be understood that during the displacement of the middle layer frame 2 relative to the bottom layer frame 1 along the X axis of the three-dimensional coordinate system and through the aforementioned horizontal hydraulic cylinder 9 and the plurality of rolling shafts 10, the plurality of load wheels 16 respectively generate a rotating action relative to the two load rails 18, the plurality of load wheels 16 and the plurality of load plates 15 remain relatively stationary relative to the bottom layer frame 1, and the two load rails 18 of the middle layer frame 2 are in a moving state relative to the bottom layer frame 1, so that the plurality of load wheels 16, the plurality of load plates 15 and the two load rails 18 do not interfere with the displacement action of the middle layer frame 2 relative to the bottom layer frame 1.

[0192] The above description is only the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation or direct or indirect application in other related technical fields based on the content of the present application specification and drawings is also included in the patent protection scope of the present application.

Claims

1. An unloading platform, characterized in that, It includes a bottom frame, a middle frame, a top frame, a lifting mechanism, a first flap, a second flap, a first limiting component, and a second limiting component. The first limiting component and the second limiting component have limiting positions and non-limiting positions relative to the middle frame, respectively. The unloading platform is set in a three-dimensional coordinate system for reference; Along the Z-axis of the three-dimensional coordinate system, the bottom frame is located below the middle frame, and the top frame is located above the middle frame. The lifting mechanism is used to change the height of the top frame relative to the middle frame. Along the X-axis of the three-dimensional coordinate system, the first flap and the second flap are rotatably disposed at both ends of the top layer frame, and the first limiting component and the second limiting component are adjustablely disposed at both ends of the middle layer frame. The top layer frame is provided with an unloading plate, which is located between the first flap and the second flap, and the first flap and the second flap are located between the first limiting component and the second limiting component. Along the Z-axis of the three-dimensional coordinate system, the distance between the first limiting component and the ground is defined as a first height threshold, which is restricted to any value between a first lower limit and a first upper limit, specifically 40 cm and 160 cm. The distance between the second limiting component and the ground is defined as a second height threshold, which is restricted to any value between a second lower limit and a second upper limit, specifically 40 cm and 120 cm. Under the condition that the first height threshold is met, the first limiting component is used to limit the angle of the first flap relative to the unloading plate, and under the condition that the second height threshold is met, the second limiting component is used to limit the angle of the second flap relative to the unloading plate.

2. The unloading platform according to claim 1, characterized in that, The first limiting component includes a first adjusting rod, a first limiter, and a second limiter; The first adjusting rod extends parallel to the Z-axis of the three-dimensional coordinate system, and the first adjusting rod is fixedly or detachably mounted on the middle frame. The first limiter includes a first sliding sleeve, a first locking bolt, and a first pulley. The first sliding sleeve is sleeved on the first adjusting rod. The first sliding sleeve is configured as a sliding pair and a rotating pair relative to the first adjusting rod. The first locking bolt is used to adjust the first sliding sleeve to be loose or locked relative to the first adjusting rod. The first pulley is disposed on the first sliding sleeve, wherein the circumferential surface of the first pulley is used to be contacted by the first flap. The second limiter includes two second sliding sleeves, a third sliding sleeve, a first limit sleeve, a first limit rod, two second locking bolts, a third locking bolt, and three second pulleys; The two second sliding sleeves and the third sliding sleeve are respectively sleeved on the first adjusting rod, and the two second sliding sleeves and the third sliding sleeve are respectively configured as a sliding pair and a rotating pair relative to the first adjusting rod; Both ends of the first limiting sleeve are fixedly connected to one of the second sliding sleeves, and one end of the first limiting rod is fixedly connected to the third sliding sleeve. Along the negative direction of the Z-axis of the three-dimensional coordinate system, the other end of the first limiting rod is inserted into the first limiting sleeve. The total length of the first limiting rod and the first limiting sleeve is greater than or equal to twice the length of the first flap, and the length of the first limiting sleeve is less than or equal to the length of the first flap. Each of the two second sliding sleeves and the third sliding sleeve is provided with one of the second pulleys. Each of the two second sliding sleeves and the third sliding sleeve is adjusted to be loose or locked relative to the first adjusting rod by one of the second locking bolts. The first limiting sleeve is provided with a first limiting surface, which is tangent to the circumferential surface of the second pulley located on the two second sliding sleeves. The first limiting rod is provided with a second limiting surface, which is tangent to the circumferential surface of the second pulley located on the third sliding sleeve. The circumferential surfaces of the three second pulleys, the first limiting surface, and the second limiting surface are respectively used to be contacted by the first flip plate. The first height threshold includes a first intermediate value and a second intermediate value, and the first lower limit, the first intermediate value, the second intermediate value and the first upper limit are set in an increasing order; The difference between the first intermediate value and the first lower limit value is equal to or less than the length of the first flap. Between the first lower limit value and the first intermediate value, the first limiter is used to limit the angle of the first flap relative to the unloading plate. The difference between the second intermediate value and the first intermediate value is equal to or less than the length of the first flap, and the difference between the first upper limit value and the second intermediate value is equal to or less than the length of the first flap. Between the first intermediate value and the second intermediate value, and between the first upper limit value and the first intermediate value, the second limiter is used to limit the angle of the first flap relative to the unloading plate.

3. The unloading platform according to claim 2, characterized in that, The second limiting assembly includes a second adjusting rod, a third limiter, and a fourth limiter; The extension direction of the second adjusting rod is parallel to the Z-axis of the three-dimensional coordinate system, and the second adjusting rod is fixedly or detachably mounted on the middle frame. The third limiter includes a fourth sliding sleeve, a fifth sliding sleeve, two fourth locking bolts, two third pulleys, and a first limit ruler; The fourth sliding sleeve and the fifth sliding sleeve are respectively sleeved on the second adjusting rod, and the fourth sliding sleeve and the fifth sliding sleeve are respectively configured as a sliding pair and a rotating pair relative to the second adjusting rod; One end of the first limiting ruler is connected to the fourth sliding sleeve. The connection position between the first limiting ruler and the fifth sliding sleeve is located between the two ends of the first limiting ruler, and the fifth sliding sleeve is located below the fourth sliding sleeve. The length of the first limiting ruler is greater than or equal to the length of the second flip plate. The fourth sliding sleeve and the fifth sliding sleeve are respectively adjusted to be loose or locked relative to the second adjusting rod by one of the fourth locking bolts. The fourth sliding sleeve and the fifth sliding sleeve are respectively provided with one of the third pulleys. The first limiting ruler has a third limiting surface, which is tangent to the circumferential surface of the two third pulleys. The third limiting surface and the circumferential surface of the two third pulleys are respectively used to be contacted by the second flip plate. The fourth limiter includes a sixth sliding sleeve, a fifth locking bolt, and a fourth pulley. The sixth sliding sleeve is sleeved on the second adjusting rod and is configured as a sliding pair and a rotating pair relative to the second adjusting rod. The fifth locking bolt is used to adjust the looseness or tightness of the sixth sliding sleeve relative to the second adjusting rod. The fourth pulley is disposed on the sixth sliding sleeve, wherein the circumferential surface of the fourth pulley is used to be contacted by the second flap. The second height threshold includes a third intermediate value and a second lower limit value, wherein the third intermediate value and the second upper limit value are set incrementally; The difference between the third intermediate value and the second lower limit value is equal to or less than the length of the second flap. Between the second lower limit value and the third intermediate value, the fourth limiter is used to limit the angle of the second flap relative to the unloading plate. The difference between the second upper limit value and the third intermediate value is equal to or less than the length of the second flap. Between the second upper limit value and the third intermediate value, the third limiter is used to limit the angle of the second flap relative to the unloading plate.

4. The unloading platform according to claim 3, characterized in that, The lengths of the first flap and the second flap are both 40 centimeters. The first intermediate value is specifically 80 centimeters, the second intermediate value is specifically 120 centimeters, and the third intermediate value is specifically 80 centimeters.

5. The unloading platform according to any one of claims 1 to 4, characterized in that, The bottom frame is equipped with a horizontal hydraulic cylinder and multiple rollers; The centerline of each roller is parallel to the Y-axis of the three-dimensional coordinate system, each roller is rotatably connected to the bottom frame, and all rollers are tangent to the same horizontal motion plane. The horizontal hydraulic cylinder has a horizontal cylinder barrel, a horizontal piston, and a horizontal hydraulic rod. The two ends of the horizontal hydraulic rod are located outside the horizontal cylinder barrel, and the intersection of the horizontal hydraulic rod and the horizontal piston is located inside the horizontal cylinder barrel. The length direction of the horizontal hydraulic rod and the length direction of the horizontal cylinder barrel are parallel to the X-axis of the three-dimensional coordinate system. The horizontal cylinder barrel is fixedly connected to the bottom frame, and the two ends of the horizontal hydraulic rod are detachably connected to the middle frame.

6. The unloading platform according to claim 5, characterized in that, The lifting mechanism includes four positioning columns, four vertical hydraulic cylinders and four pushing components, each of which is equipped with a sprocket and a chain; The extension direction of each of the positioning posts is parallel to the Z-axis of the three-dimensional coordinate system, and each of the positioning posts is respectively disposed in the middle frame; The vertical hydraulic cylinder includes a vertical hydraulic rod, a vertical piston, and a vertical cylinder. The two ends of the vertical hydraulic rod are located outside the vertical cylinder, and the intersection of the vertical hydraulic rod and the vertical piston is located inside the vertical cylinder. The length directions of the vertical hydraulic rod and the vertical cylinder are parallel to the Z-axis of the three-dimensional coordinate system. The vertical hydraulic rod is fixedly connected to the middle frame. Along the Z-axis of the three-dimensional coordinate system, the vertical cylinder is used to push the jacking component; The sprocket and the chain form a transmission pair, wherein one end of the chain is connected to the middle frame and the other end of the chain is connected to the top frame.

7. The unloading platform according to claim 6, characterized in that, The lifting mechanism also includes four stop components; Each of the positioning posts is provided with a stop component, wherein the stop component is located at the lower part of the pushing component along the Z-axis of the three-dimensional coordinate system, and a gap is formed between the stop component and the middle frame.

8. The unloading platform according to claim 6, characterized in that, Each of the pushing components is provided with a first positioning wheel and a second positioning wheel, and the first positioning wheel and the second positioning wheel are rotatably connected to the pushing component; The positioning column has a first side plate, a second side plate, and a connecting plate. The first side plate and the second side plate are parallel to each other, and the connecting plate is located between the first side plate and the second side plate. The first side plate, the connecting plate, and the second side plate form an I-beam structure. The first positioning wheel is restricted to contacting the first side plate, and the second positioning wheel is restricted to contacting the second side plate.

9. The unloading platform according to claim 6, characterized in that, It also includes four first omnidirectional wheels and four support feet, each of the support feet being welded to one corner of the bottom frame, and each of the first omnidirectional wheels being connected to the bottom frame and one of the support feet.

10. The unloading platform according to claim 9, characterized in that, It also includes four second rollers, four telescopic components, multiple load-bearing plates, and multiple load-bearing wheels; Each of the telescopic components includes a spring, a positioning sleeve, and a transmission rod. The positioning sleeve is welded to the middle frame, and the length direction of the positioning sleeve is parallel to the Z-axis of the three-dimensional coordinate system. The transmission rod and the positioning sleeve form a sleeve structure. Along the Z-axis of the three-dimensional coordinate system, the transmission rod has a top end that can be exposed on the upper part of the middle frame and a bottom end that can be exposed on the lower part of the middle frame. The top end is provided with a stepped portion, the diameter of which is larger than the diameter of the transmission rod. One of the second rollers is provided at the bottom end. Each of the vertical cylinders is provided with a driving component, which is welded to the vertical cylinder. The driving component is used to drive the transmission rod along the direction from the top end to the bottom end. The middle frame is provided with two load-bearing rails, the length direction of each load-bearing rail is parallel to the X-axis of the three-dimensional coordinate system, the two load-bearing rails are isolated by the bottom frame, and the two load-bearing rails are parallel to each other. The load-bearing plates are divided into two groups. The load-bearing plates of the first group and the load-bearing plates of the second group are separated by the bottom frame. One end of each load-bearing plate is fixedly or detachably connected to the bottom frame. The other end of each load-bearing plate is rotatably provided with one of the load-bearing wheels. Along the direction from the top end to the bottom end, each load-bearing wheel contacts one of the load-bearing rails.

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