Prefabricated hollow beam type stair

Abstract

The application relates to a prefabricated hollow beam type stair, and relates to the technical field of beam type stairs. The application comprises two oppositely arranged stair beams, the upper surface of the stair beam is provided with a folded plate step, a plurality of mounting rods are slidably connected in the stair beam, a plurality of mounting rods are slidably connected on the stair beam, a plurality of mounting holes for inserting the mounting rods are formed in the folded plate step, a positioning assembly is arranged on the mounting rod, a driving assembly is arranged in the stair beam, the driving assembly is connected with the mounting rod, the driving assembly is used for driving the mounting rod to be inserted into the mounting hole, the positioning assembly abuts against the folded plate step and is used for fixing the mounting rod on the folded plate step. The application has the effect that the folded plate step and the stair beam are more convenient to install.

Description

Technical Field

[0001] This application relates to the field of beam staircases, and more particularly to a precast hollow beam staircase. Background Technology

[0002] A beam-type staircase refers to a staircase where the treads are placed directly on inclined beams, which in turn rest on stair beams at both ends of the staircase (sometimes three inclined beams are used due to load-bearing requirements). Hollow beam staircases, on the other hand, often have closed blind openings in the treads to reduce their weight.

[0003] In related technologies, Chinese patent CN208455984U discloses a precast hollow beam staircase, including a multi-step precast cement stair slab with embedded steel bars. Each step of the precast cement stair slab also has multiple embedded PVC pipes. The staircase also includes two precast beams symmetrically arranged on both sides of the bottom surface of the precast cement stair slab, with each beam having a step surface that aligns with the steps on the stair slab. Regarding the connection between the beams and steps, Chinese patent CN218091695U discloses a split precast beam staircase structure, including two stair beams. The upper surfaces of the two stair beams are connected to folded plate steps. Multiple step grooves are equidistantly spaced on the upper surfaces of the two stair beams, and each of the multiple step grooves has a second screw hole on its upper surface. The upper surface of the stair beam has first screw holes corresponding to multiple second screw holes, and the inner side of each first screw hole is threaded with a fixing screw. By tightening the bolts into the first and second screw holes, the folded plate step and the stair beam are connected.

[0004] The installation of multi-step steps is achieved by sequentially screwing several screws into the corresponding first and second screw holes, which is inconvenient and needs improvement. Summary of the Invention

[0005] To address the inconvenience of installing multiple steps sequentially using several bolts, this application provides a prefabricated hollow beam staircase.

[0006] This application provides a precast hollow beam staircase with the following technical solution:

[0007] The utility model provides a prefabricated hollow beam type stair, including two opposite setting two ladder beams, the upper surface of ladder beam is equipped with the step of folding plate, a plurality of installation rods are connected in the sliding of ladder beam, a plurality of installation rods are connected in the sliding of ladder beam, a plurality of installation holes are seted up for the insertion of installation rod on the step of folding plate, the upper surface of step of folding plate is equipped with the positioning assembly, the driving assembly is equipped in the ladder beam, the driving assembly is connected with installation rod, the driving assembly is used for driving installation rod and inserts in installation hole, the positioning assembly is abutted with the step of folding plate, is used for fixing installation rod on the step of folding plate.

[0008] By adopting the above technical scheme, when installing, the step of folding plate is placed on the upper surfaces of the two ladder beams, the step of folding plate is supported by the two ladder beams on both sides, so that the plurality of installation holes on the step of folding plate correspond to the installation rods, then the driving assembly is used to push the installation rods to move towards the step of folding plate until the installation rods are inserted into the installation holes, at this time, the positioning assembly is abutted with the step of folding plate, so as to fix the installation rods on the step of folding plate, and the installation rods are also connected by the driving assembly and the ladder beams, so that the step of folding plate is fixedly connected with the ladder beams, that is, only by moving the driving assembly, the plurality of installation rods in the same ladder beam can be inserted into the installation holes and fixed at the same time, compared with connecting the step of folding plate by a plurality of bolts in sequence, the operation is more convenient.

[0009] Optionally, the upper surface of the ladder beam is provided with a plurality of installation grooves, the step of folding plate is adapted to be inserted into the installation grooves, the upper surfaces of the plurality of installation grooves are provided with connecting holes, each installation hole corresponds to one connecting hole, and each installation rod is inserted into one connecting hole and can move in the connecting hole.

[0010] By adopting the above technical scheme, when installing, the step of folding plate is inserted into the installation grooves, so that the step of folding plate and the ladder beam are more matched, so that the bending part of the step of folding plate can also be supported, thereby increasing the stability of the step of folding plate installed on the ladder beam.

[0011] Optionally, the driving assembly includes a rotating rack, a plurality of transmission rods and a plurality of connecting rods, the ladder beam is provided with a cavity, the connecting hole is communicated with the cavity, the rotating rack is slidably connected to the inner wall of the cavity, the rotating rack is arranged along the length direction of the ladder beam, a plurality of rotating blocks are fixed on the rotating rack, one end of each transmission rod is hingedly connected to one rotating block, the other end is hingedly connected to one end of the connecting rod, the bottom end of the installation rod is hingedly connected to one end of the connecting rod close to the transmission rod, the other end of the connecting rod away from the transmission rod is hingedly connected to the inner wall of the cavity, and the rotating rack moves along the length direction of the ladder beam to drive the connecting rod to move the installation rod towards or away from the step of folding plate.

[0012] By adopting the above technical scheme, when the folded plate step is inserted in the mounting groove, the driving rotating rack is moved downward along the length direction of the ladder beam, the rotating block is moved toward the connecting rod, the distance between the transmission rod and the connecting rod is shortened, the included angle between the transmission rod and the connecting rod is reduced, the connecting rod is rotated around the connecting position between the connecting rod and the inner wall of the cavity, the mounting rod is moved upward, the mounting rod can be inserted in the connecting hole, then the positioning assembly fixes the mounting rod and the folded plate step, and the folded plate step is fixedly installed on the ladder beam, so that the operation is convenient.

[0013] Optionally, the positioning assembly comprises a positioning block and a positioning spring, a positioning hole is formed in the side wall of the mounting rod and located at the top of the mounting rod, the positioning rod is inserted in the positioning hole and can move in the positioning hole, the positioning block is fixed to the inner wall of the positioning hole through the positioning spring, a guide surface is arranged on the side wall of the positioning block, the top end of the guide surface is inclined to the mounting rod, and the folded plate step abuts against the guide surface and is used for accommodating the positioning block in the positioning hole.

[0014] By adopting the above technical scheme, when the connecting rod pushes the mounting rod to be inserted in the mounting hole from bottom to top, the guide surface first abuts against the folded plate step, the guide surface plays a guiding role, the folded plate step slides on the guide surface, the positioning block is accommodated in the positioning hole by extruding the positioning spring, and the positioning block is completely accommodated in the positioning hole, so that the mounting rod can move in the mounting hole, when the top end of the mounting rod extends out of the mounting hole and the positioning block moves to be separated from the mounting hole, the positioning block is limited, the positioning block is popped out of the positioning hole under the action of the positioning spring, the bottom wall of the positioning block abuts against the folded plate step and limits the folded plate step from being separated from the ladder beam, the folded plate step and the ladder beam are fixedly installed, and the operation is convenient.

[0015] Optionally, a plurality of accommodating grooves are formed in the upper surface of the folded plate step, the accommodating grooves are communicated with the mounting hole, and the accommodating grooves can accommodate the positioning block.

[0016] By adopting the above technical scheme, when the top end of the mounting rod is inserted in the accommodating groove through the mounting hole, the positioning block also completely enters the accommodating groove, the positioning block abuts against the inner wall of the accommodating groove after being popped out of the positioning hole, the folded plate step is limited to move away from the ladder beam, and at this time, the top end of the mounting rod is also located in the accommodating groove, so that the structure of the top end of the mounting rod and the positioning block does not protrude from the upper surface of the folded plate step, the upper surface of the folded plate step is not provided with a protruding obstacle, and the person walking on the folded plate step is prevented from stumbling or being scratched, so that the person is not easily hurt, and the safety is improved.

[0017] Optionally, the bottoms of the two ladder beams are connected through a mounting plate, and the mounting plate is provided with a moving mechanism for driving the two rotating racks to move simultaneously.

[0018] By adopting the technical scheme, the installation plate fixes the two ladder beams, so that the two ladder beams are not prone to tilting, and the distance between the two ladder beams is fixed, that is, the two ladder beams will not move, thereby increasing the stability of the overall structure. When the folding plate step needs to be installed, the moving mechanism is directly started to synchronously move the two rotating racks, so that the folding plate step is fixed and connected with the two ladder beams at the same time, which is convenient to operate and has better coordination.

[0019] Optionally, the moving mechanism comprises a moving rod, a rotating assembly and two rotating gears, the moving rod is rotationally connected to the installation plate, the moving rod is arranged along the length direction of the installation plate, the rotating gears are coaxially sleeved on the moving rod, the two rotating gears are fixed at the two ends of the moving rod respectively, the two rotating gears are meshed with the corresponding rotating racks respectively, the rotating assembly is arranged on the installation plate, and the rotating assembly is connected with the moving rod and used to drive the moving rod to rotate about the central axis of the moving rod.

[0020] By adopting the technical scheme, when the folding plate step is placed in the installation groove, the rotating assembly is used to drive the moving rod to rotate, so that the two rotating gears rotate at the same time, thereby driving the two corresponding rotating racks to move downward along the length direction of the ladder beam at the same time, realizing synchronous upward rotation of the two connecting rods, driving all the installation rods to be inserted in the installation holes at the same time, until the positioning blocks are inserted in the accommodating grooves and abut against the inner walls of the accommodating grooves, thereby realizing fixation of all the installation rods, which is convenient to operate.

[0021] Optionally, the rotating assembly comprises a rotating bevel gear and a transmission bevel gear, the transmission bevel gear is coaxially sleeved on the moving rod, the transmission bevel gear is fixed with the moving rod, the rotating bevel gear is rotationally connected to the installation plate, the rotating bevel gear is coaxially fixed with a rotating rod, and the rotating rod is rotationally connected to the installation plate.

[0022] By adopting the technical scheme, the rotating rod is driven to rotate, so that the rotating bevel gear rotates, the transmission bevel gear is driven to rotate, and the moving rod is rotated, which is convenient to operate.

[0023] Optionally, the upper surface of the folding plate step is provided with a protective pad, and the top and bottom of the protective pad are fixed on the folding plate step by bolts.

[0024] By adopting the technical scheme, when a person falls on the folding plate step, the protective pad can play a protective and buffering role, so that the person is not easily injured, and the safety is relatively high.

[0025] Optionally, a fixed block is coaxially fixed at the end of the rotating rod away from the rotating bevel gear, a plurality of fixed grooves are arranged on the circumferential side wall of the fixed block, a limiting groove is arranged on the side wall of the protective pad, the fixed block can be inserted into the limiting groove, and a plurality of limiting blocks are arranged on the inner wall of the limiting groove and correspondingly inserted into the fixed grooves.

[0026] By adopting the above technical scheme, when the protective pad is laid on the folding plate step, the two ends of the protective pad in the length direction are respectively abutted and fixed on the ladder beams by bolts, the fixed block is inserted into the limiting groove, the limiting blocks are correspondingly inserted into the fixed grooves, the inner wall of the limiting blocks abuts against the side wall of the fixed grooves, the protective pad cannot move due to the influence of the bolts, that is, the limiting blocks are fixed, so that the rotation of the fixed block is limited, the rotating bevel gear is fixed, the state of the connecting rod pushing the installation rod is maintained, and the stability of the installation rod inserted into the installation hole is improved.

[0027] In summary, the present application has at least one of the following beneficial effects:

[0028] 1. During installation, the folding plate step is placed on the upper surfaces of the two ladder beams, the two ladder beams support the two sides of the folding plate step, the plurality of installation holes on the folding plate step correspond to the installation rods, then the installation rods are moved in the direction of the folding plate step by the driving assembly until the installation rods are inserted into the installation holes, at this time, the positioning assembly abuts against the folding plate step, so that the installation rods are fixed on the folding plate step, and the installation rods are also connected by the driving assembly and the ladder beams, so that the folding plate step is fixedly connected with the ladder beams, that is, only by moving the driving assembly, the plurality of installation rods in the same ladder beam can be simultaneously inserted into the installation holes and fixed, compared with connecting the folding plate step by a plurality of bolts in sequence, the operation is more convenient.

[0029] 2. After the folding plate step is inserted into the installation groove, the rotating rack is driven to move downward along the length direction of the ladder beam, so that the rotating block moves in the direction of the connecting rod, thereby the distance between the transmission rod and the connecting rod is shortened, that is, the included angle between the transmission rod and the connecting rod is reduced, the connecting rod rotates around the connection between the connecting rod and the inner wall of the cavity, and drives the installation rod to move upward, so that the installation rod can be correspondingly inserted into the connecting hole, then the positioning assembly fixes the installation rod and the folding plate step, and further fixes and installs the folding plate step on the ladder beam, and the operation is convenient. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a structural schematic view of the prefabricated hollow beam type stair of the embodiment of the present application;

[0031] Figure 2 It is a structural sectional view of the prefabricated hollow beam type stair of the embodiment of the present application;

[0032] Figure 3 It isFigure 2 Enlarged view of the middle A;

[0033] Figure 4 Structural sectional view of the mounting plate.

[0034] In the figure: 10, ladder beam; 11, cavity; 12, connecting hole; 13, mounting slot; 20, folded plate step; 21, mounting hole; 22, accommodating slot; 30, mounting rod; 31, positioning hole; 40, positioning assembly; 41, positioning block; 411, guide surface; 42, positioning spring; 50, driving assembly; 51, rotating rack; 511, rotating block; 52, transmission rod; 53, connecting rod; 60, mounting plate; 70, moving assembly; 71, moving rod; 72, rotating gear; 73, rotating assembly; 731, rotating bevel gear; 732, transmission bevel gear; 733, rotating rod; 80, protective pad; 81, limiting slot; 811, limiting block; 90, bolt; 120, fixed block; 121, fixed slot. DETAILED DESCRIPTION

[0035] The following will be further explained in detail with reference to the accompanying drawings. Figures 1-4 The present application is further explained in detail.

[0036] The present application discloses a prefabricated hollow beam type staircase. Referring to Figure 1 and Figure 2 , the prefabricated hollow beam type staircase comprises a folded plate step 20 placed obliquely, two opposite ladder beams 10 are arranged below the folded plate step 20, the ladder beams 10 support the two sides of the folded plate step 20, in order to increase the stability of the ladder beams 10 and the folded plate step 20, a plurality of mounting slots 13 are arranged on the upper surface of the ladder beams 10, so that each step of the folded plate step 20 can be placed on the mounting slots 13, thereby supporting the bending part of the folded plate step 20, and further increasing the stability of the folded plate step 20 mounted on the ladder beams 10.

[0037] Referring to Figure 2 and Figure 3 , the cavity 11 is arranged in the ladder beam 10, the upper surface of the mounting slot 13 is arranged with a plurality of connecting holes 12 communicating with the cavity 11, the mounting hole 21 is arranged on the folded plate step 20 corresponding to the position of the connecting hole 12, the mounting rod 30 is arranged in the connecting hole 12, the driving assembly 50 is arranged in the cavity 11 for driving the mounting rod 30 to move upward and be inserted into the mounting hole 21, and the positioning assembly 40 is arranged on the mounting rod 30 for fixing the mounting rod 30 in the mounting hole 21 after the mounting rod 30 is inserted into the mounting hole 21.

[0038] Referring to Figure 2 and Figure 3, the driving assembly 50 comprises a rotating rack 51, a plurality of transmission rods 52 and a plurality of connecting rods 53, the rotating rack 51 is embedded on the inner wall of the cavity 11 and can move along the length direction of the ladder beam 10, the rotating rack 51 is arranged along the length direction of the ladder beam 10, a plurality of rotating blocks 511 are fixed on the rotating rack 51, one end of each transmission rod 52 is hingedly connected with one rotating block 511, the other end is hingedly connected with one end of the connecting rod 53, the bottom end of the mounting rod 30 is hingedly connected with one end of the connecting rod 53 close to the transmission rod 52, and the other end of the connecting rod 53 away from the transmission rod 52 is hingedly connected with the inner wall of the cavity 11, the rotating rack 51 moves along the length direction of the ladder beam 10 to drive the connecting rod 53 to move the mounting rod 30 up and down.

[0039] When the folding plate step 20 is inserted into the mounting groove 13, the rotating rack 51 is driven to move downward along the length direction of the ladder beam 10, so that the rotating block 511 moves towards the connecting rod 53, thereby shortening the distance between the transmission rod 52 and the connecting rod 53, i.e. reducing the included angle between the transmission rod 52 and the connecting rod 53, so that the connecting rod 53 rotates around the connection between the connecting rod 53 and the inner wall of the cavity 11 and drives the mounting rod 30 to move upward, so that the mounting rod 30 can be inserted into the connecting hole 12.

[0040] Referring to Figure 2 and Figure 3 , the positioning assembly 40 comprises a positioning block 41 and a positioning spring 42, the side wall of the mounting rod 30 is provided with a positioning hole 31, the positioning hole 31 is located at the top of the mounting rod 30, the positioning rod is inserted into the positioning hole 31 and can move in the positioning hole 31, the positioning block 41 is fixed with the inner wall of the positioning hole 31 through the positioning spring 42, the side wall of the positioning block 41 is provided with a guide surface 411, and the top end of the guide surface 411 is inclinedly arranged towards the mounting rod 30.

[0041] When the connecting rod 53 pushes the mounting rod 30 to insert into the mounting hole 21 from bottom to top, the guide surface 411 first abuts against the folding plate step 20, the guide surface 411 plays a guiding role, so that the folding plate step 20 slides on the guide surface 411, thereby the positioning block 41 extrudes the positioning spring 42 and is accommodated in the positioning hole 31, until the positioning block 41 is completely accommodated in the positioning hole 31, so as to facilitate the movement of the mounting rod 30 in the mounting hole 21, when the top end of the mounting rod 30 protrudes out of the mounting hole 21 and the positioning block 41 moves to separate from the mounting hole 21, at this time, the positioning block 41 loses the limitation, under the action of the positioning spring 42, the positioning block 41 pops out of the positioning hole 31, the bottom wall of the positioning block 41 abuts against the folding plate step 20, limiting the folding plate step 20 from separating from the ladder beam 10, achieving the fixed installation of the folding plate step 20 and the ladder beam 10,

[0042] Referring to Figure 2 and Figure 3In order to avoid the upper surface of the folding plate step 20 being convex and causing harm to people walking on the folding plate step 20, a containing groove 22 is arranged on the upper surface of the folding plate step 20, the containing groove 22 is communicated with the mounting hole 21, when the positioning block 41 is completely inserted into the containing groove 22, the top end of the mounting rod 30 also passes through the mounting hole 21 and is located in the containing groove 22, at this time, the top end of the mounting rod 30 does not protrude from the containing groove 22, the upper surface of the folding plate step 20 is not convex, and the safety is improved.

[0043] Referring to Figure 1 and Figure 4 The mounting plate 60 is arranged between the two ladder beams 10, the two ends of the mounting plate 60 are fixed with the two ladder beams 10 respectively, so that the structure of the two ladder beams 10 is more fixed, the moving mechanism is arranged on the mounting plate 60, so that the two rotating racks 51 can move synchronously, the moving mechanism includes the moving rod 71 and the two rotating gears 72, the moving rod 71 is rotationally connected on the mounting plate 60, the moving rod 71 is arranged along the length direction of the mounting plate 60, the rotating gear 72 is coaxially sleeved on the moving rod 71, the two rotating gears 72 are fixed on the two ends of the moving rod 71 respectively, and the two rotating gears 72 are respectively engaged with the corresponding rotating racks 51.

[0044] When the folding plate step 20 is placed in the mounting groove 13, the moving rod 71 is driven to rotate, so that the two rotating gears 72 are simultaneously rotated, thereby driving the two corresponding rotating racks 51 to move downward along the length direction of the ladder beam 10 simultaneously, realizing the synchronous upward rotation of the two side connecting rods 53, driving all the mounting rods 30 to be simultaneously inserted into the mounting holes 21, until the positioning block 41 is inserted into the containing groove 22 and abuts against the inner wall of the containing groove 22, realizing the fixation of all the mounting rods 30, and the operation is convenient.

[0045] Referring to Figure 1 and Figure 4 The moving mechanism further includes the rotating assembly 73 for driving the moving rod 71 to rotate, the rotating assembly 73 includes the rotating bevel gear 731 and the transmission bevel gear 732, the transmission bevel gear 732 is coaxially sleeved on the moving rod 71, the transmission bevel gear 732 is fixed with the moving rod 71, the rotating bevel gear 731 is rotationally connected on the mounting plate 60, the rotating bevel gear 731 is coaxially fixed with the rotating rod 733, and the rotating rod 733 is rotationally connected on the mounting plate 60. The rotating rod 733 is driven to rotate, so that the rotating bevel gear 731 is rotated, the transmission bevel gear 732 is driven to rotate, and the moving rod 71 is rotated.

[0046] Referring to Figure 1 and Figure 4, in order to prevent people from slipping on the folding plate step 20 to fall, a protective pad 80 is laid on the upper surface of the folding plate step 20, and the protective pad 80 is laid according to the track of the folding plate step 20. The top and bottom of the protective pad 80 are fixed on the folding plate step 20 by bolts 90.

[0047] Referring to Figure 1 and Figure 4 The end of the rotating rod 733 away from the rotating bevel gear 731 is coaxially fixed with a fixed block 120, a plurality of fixed grooves 121 are arranged on the circumferential side wall of the fixed block 120, a limiting groove 81 is formed on the side wall of the protective pad 80, the fixed block 120 can be inserted into the limiting groove 81, and a plurality of limiting blocks 811 are integrally formed on the inner wall of the limiting groove 81, and the limiting blocks 811 are correspondingly inserted into the fixed grooves 121.

[0048] When the protective pad 80 is laid on the folding plate step 20, the fixed block 120 is inserted into the limiting groove 81, the limiting blocks 811 are correspondingly inserted into the fixed grooves 121, the inner wall of the limiting blocks 811 abuts against the side wall of the fixed grooves 121, and the protective pad 80 cannot move due to the influence of the bolts 90, that is, the limiting blocks 811 are fixed, so as to limit the rotation of the fixed block 120, so that the rotating bevel gear 731 is fixed, that is, the state that the connecting rod 53 pushes the installation rod 30 is maintained, and the stability of the installation rod 30 inserted into the installation hole 21 is increased.

[0049] The implementation principle of the prefabricated hollow beam type stair of the embodiment of the application is as follows: when installing, the folding plate step 20 is placed on the upper surfaces of the two stair beams 10, the two stair beams 10 support the two sides of the folding plate step 20, so that the plurality of installation holes 21 on the folding plate step 20 correspond to the installation rods 30 one by one, then the driving assembly 50 is used to push the installation rod 30 to move towards the folding plate step 20, until the installation rod 30 is inserted into the installation hole 21, at this time, the positioning assembly 40 abuts against the folding plate step 20, so as to fix the installation rod 30 on the folding plate step 20, and the installation rod 30 is also connected through the driving assembly 50 and the stair beam 10, so that the folding plate step 20 is fixedly connected with the stair beam 10, that is, only by moving the driving assembly 50, the plurality of installation rods 30 in the same stair beam 10 can be simultaneously inserted into the installation holes 21 and fixed, compared with connecting the folding plate step 20 through a plurality of bolts 90 one by one, the operation is more convenient.

[0050] The above are preferred embodiments of the application, which do not limit the protection scope of the application, therefore: any equivalent changes made according to the structure, shape and principle of the application should be covered within the protection scope of the application.

Claims

1. A precast hollow beam stairway characterized by, The application relates to a ladder beam (10) with a foldable step (20) and a positioning assembly (40), the ladder beam (10) is provided with the foldable step (20) on the upper surface, a plurality of installation rods (30) are slidably connected in the ladder beam (10), a plurality of installation holes (21) for inserting the installation rods (30) are formed in the foldable step (20), the positioning assembly (40) is arranged on the installation rod (30), a driving assembly (50) is arranged in the ladder beam (10) and connected with the installation rod (30), the driving assembly (50) is used for driving the installation rod (30) to be inserted into the installation hole (21), the positioning assembly (40) is abutted with the foldable step (20) and used for fixing the installation rod (30) on the foldable step (20). A plurality of installation grooves (13) are formed in the upper surface of the ladder beam (10), the foldable step (20) is inserted into the installation groove (13), the upper surfaces of the installation grooves (13) are provided with connecting holes (12), each installation hole (21) corresponds to one connecting hole (12), and each installation rod (30) is correspondingly inserted into one connecting hole (12) and can move in the connecting hole (12). The driving assembly (50) comprises a rotating rack (51), a plurality of transmission rods (52) and a plurality of connecting rods (53), a cavity (11) is formed in the ladder beam (10), the connecting hole (12) is communicated with the cavity (11), the rotating rack (51) is slidably connected to the inner wall of the cavity (11), the rotating rack (51) is arranged along the length direction of the ladder beam (10), a plurality of rotating blocks (511) are fixed on the rotating rack (51), one end of each transmission rod (52) is hingedly connected to one rotating block (511), the other end is hingedly connected to one end of the connecting rod (53), the bottom end of the installation rod (30) is hingedly connected to one end of the connecting rod (53) close to the transmission rod (52), the other end of the connecting rod (53) away from the transmission rod (52) is hingedly connected to the inner wall of the cavity (11), and the rotating rack (51) moves along the length direction of the ladder beam (10) and drives the connecting rod (53) to drive the installation rod (30) to move towards the foldable step (20) or away from the foldable step (20). The positioning assembly (40) comprises a positioning block (41) and a positioning spring (42), a positioning hole (31) is formed in the side wall of the installation rod (30), the positioning hole (31) is located at the top of the installation rod (30), the positioning rod is inserted into the positioning hole (31) and can move in the positioning hole (31), the positioning block (41) is fixed to the inner wall of the positioning hole (31) through the positioning spring (42), a guide surface (411) is arranged on the side wall of the positioning block (41), the top end of the guide surface (411) is inclinedly arranged towards the installation rod (30), the foldable step (20) is abutted with the guide surface (411) and used for accommodating the positioning block (41) in the positioning hole (31).

2. The precast hollow beam stair of claim 1, wherein, The upper surface of the folding plate step (20) is provided with a plurality of accommodating grooves (22) in communication with the mounting holes (21), and the accommodating grooves (22) can accommodate positioning blocks (41).

3. The precast hollow beam stair of claim 1, wherein, The bottoms of the two ladder beams (10) are connected through a mounting plate (60), and the mounting plate (60) is provided with a moving mechanism for driving the two rotating racks (51) to move simultaneously.

4. The precast hollow beam stair of claim 3, wherein, The moving mechanism comprises a moving rod (71), a rotating assembly (73) and two rotating gears (72), the moving rod (71) is rotatably connected to the mounting plate (60), the moving rod (71) is arranged along the length direction of the mounting plate (60), the rotating gears (72) are coaxially sleeved on the moving rod (71), the two rotating gears (72) are respectively fixed at the two ends of the moving rod (71), the two rotating gears (72) are respectively engaged with the corresponding rotating racks (51), the rotating assembly (73) is arranged on the mounting plate (60), the rotating assembly (73) is connected with the moving rod (71), and the rotating assembly (73) is used for driving the moving rod (71) to rotate about the central axis of the moving rod (71).

5. The precast hollow beam stair of claim 4, wherein, The rotating assembly (73) comprises a rotating bevel gear (731) and a transmission bevel gear (732), the transmission bevel gear (732) is coaxially sleeved on the moving rod (71), the transmission bevel gear (732) is fixed with the moving rod (71), the rotating bevel gear (731) is rotatably connected to the mounting plate (60), and the rotating bevel gear (731) is coaxially fixed with a rotating rod (733).

6. The precast hollow beam stair of claim 5, wherein, The upper surface of the folding plate step (20) is provided with a protective pad (80), and the top and bottom of the protective pad (80) are fixed on the folding plate step (20) through bolts (90).

7. The precast hollow beam stair of claim 6, wherein, The end of the rotating rod (733) away from the rotating bevel gear (731) is coaxially fixed with a fixed block (120), the circumferential side wall of the fixed block (120) is provided with a plurality of fixed grooves (121), the side wall of the protective pad (80) is provided with a limiting groove (81), the fixed block (120) can be inserted into the limiting groove (81), and the inner wall of the limiting groove (81) is provided with a plurality of limiting blocks (811).

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