A large-span refined steel truss structure and preparation method thereof

Abstract

The present invention belongs to the field of curtain wall engineering, and specifically relates to a large-span fine steel truss structure and a preparation method thereof. In view of the problem in the prior art that the traditional aluminum alloy frame system cannot adapt to the force requirements of large spans and large spaces, a large-span fine steel truss structure and a preparation method thereof are provided, comprising a plurality of sheet trusses that can be assembled with each other, the sheet trusses comprising an outer chord, an inner chord and a stiffened rib, and clamps capable of adjusting the spacing are respectively installed on the lower sides of two adjacent sheet trusses; the outer chord and the inner chord are respectively clamped and limited by the clamps, thereby solving the problem of the precision of the fine steel trusses in an ultra-long span, and by adopting laser cutting and assembling and welding on a three-dimensional flexible working platform, the assembly deformation and welding stress deformation are effectively controlled, and robot welding is adopted to ensure that the welding is straight and smooth, and to ensure that the straightness of the truss, the cross-sectional distortion, and the precision of the cross-sectional R angle meet the design requirements.

Description

Technical Field

[0001] The invention belongs to the field of curtain wall engineering, and in particular relates to a large-span refined steel truss structure and a preparation method thereof. Background Art

[0002] Curtain wall is the exterior wall enclosure of a building. It is non-load-bearing and is a lightweight wall with decorative effects commonly used in modern large and high-rise buildings. It is composed of panels and a supporting structure system. It has a certain displacement ability relative to the main structure or a certain deformation ability itself, and is a building exterior enclosure structure or decorative structure that does not bear the effects of the main structure. Curtain wall engineering is a general term for the installation and construction of metal plates or safety glass used for building enclosure components and decorative panels. The installation of curtain walls must meet design requirements and must be firmly installed to ensure safety. Curtain wall engineering has many large-span and large-space facade structures. The traditional aluminum alloy frame system cannot adapt to the force requirements. There is a lack of a large-span exquisite steel truss that can meet the force requirements of large-span spaces and have the visual effect of aluminum profile surfaces. Summary of the invention

[0003] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a large-span refined steel truss structure and a preparation method thereof, which effectively solves the problems mentioned in the above background technology.

[0004] In order to solve the above problems, the technical solution adopted by the present invention is:

[0005] A large-span exquisite steel truss structure comprises a plurality of sheet trusses which can be assembled with each other, the sheet trusses comprising an outer chord, an inner chord and a reinforced rib, and clamps capable of adjusting the spacing are respectively installed on the lower sides of two adjacent sheet trusses; the outer chord and the inner chord are respectively clamped and limited by the clamps to facilitate welding; the clamp comprises a mounting frame and clamping plates respectively slidably connected to both sides of the upper end of the mounting frame, the two clamping plates can respectively move along the length direction of the clamping plates, the outer sides of the two corresponding clamping plates are respectively fixedly connected with clamping springs, and the outer ends of the clamping springs are respectively fixedly connected with the mounting frame; the lower ends of the mounting frames are respectively fixedly connected with connecting tubes, the lower sides of the connecting tubes are connected with positioning columns, and the interior of the connecting tubes is provided with a fixing structure engaging with the positioning columns.

[0006] Furthermore, the front of the outer chord rod and the inner chord rod are respectively fixedly connected with a plug plate and a plug core, and the rear ends of the outer chord rod and the inner chord rod are respectively provided with sockets that can be engaged with the plug plate and the plug core respectively. During assembly, the adjacent plug plates and the plug core are respectively inserted into the corresponding sockets, and the upper ends of the plug plates and the plug core are respectively provided with positioning holes and first key-shaped holes downwardly, and the rear sides of the upper ends of the outer chord rod and the inner chord rod surfaces are respectively provided with third key-shaped holes and second key-shaped holes. When the plug plate and the plug core are respectively inserted into the sockets, the positioning holes and the first key-shaped holes correspond to the third key-shaped holes and the second key-shaped holes respectively, and rectangular openings are respectively provided on the right sides of the rear ends of the outer chord rod and the inner chord rod, and when the sheet trusses are butt-jointed at right angles, the plug plates and the plug core can be respectively inserted into the corresponding rectangular openings.

[0007] Furthermore, a first connecting plate and a second connecting plate are fixedly connected between two correspondingly arranged front and rear mounting frames, respectively. A connecting groove is opened at the front end of the first connecting plate toward the rear side, and the first connecting plate is slidably connected inside the connecting groove.

[0008] Furthermore, an adjustment cylinder and an adjustment screw are respectively arranged between the two corresponding installation frames on the left and right. One end of the adjustment screw corresponding to the adjustment cylinder is threadedly connected to the inside of the adjustment cylinder, and the other end of the adjustment cylinder is fixedly connected to the corresponding installation frame. The other end of the adjustment screw is fixedly connected with an adjustment knob, and the adjustment knob is rotatably connected to the corresponding installation frame.

[0009] Furthermore, a strip-shaped opening is axially opened on the surface of the adjusting cylinder, a sliding plate is axially slidably connected to the inside of the adjusting cylinder, the sliding plate is rotatably connected to one end of the adjusting screw entering the adjusting cylinder, a connecting block is fixedly connected to the circumferential surface of the sliding plate, the connecting block is slidably connected to the strip-shaped opening, pointers are respectively fixedly connected to the outer ends of the connecting frames, the pointers are slidably connected to the surface of the adjusting cylinder, and a distance scale matching the pointer is axially opened on the surface of the adjusting cylinder.

[0010] A method for preparing a large-span fine steel truss structure comprises the following steps:

[0011] S1: The outer chord, inner chord and stiffened ribs are cut from original plates by laser, the cross sections are grooved, and after being straightened, they are assembled and spot welded, and then fully welded after being limited and fixed by a clamp. After the outer chord and the inner chord are fully welded, they are straightened for the second time;

[0012] S2: Place the outer chord and the inner chord flat on the working platform, weld the reinforced ribs, and use symmetrical welding and intermittent welding to release stress deformation and expansion deformation;

[0013] S3: The length span is made by splicing in three sections. The plug board and the plug core are inserted into the corresponding sockets respectively, and the surface is clamped and fixed by a clamp to prevent splicing deformation;

[0014] S4: After the surface is sandblasted and polished, it is primed and mid-coated. After passing the inspection, the next process is carried out.

[0015] The present invention has novel structure, ingenious design, simple and convenient operation, and has the following advantages compared with the prior art:

[0016] 1. The present invention solves the problem of precision of fine steel trusses in ultra-long spans. By using laser cutting to improve the processing precision of the plate, the assembly and welding are carried out on a three-dimensional flexible working platform, the assembly deformation and welding stress deformation are effectively controlled, and robot welding is used to ensure that the welding is straight and smooth. The above measures and methods can ensure that the straightness, cross-section distortion, and cross-section R angle accuracy of the truss meet the design requirements;

[0017] 2. The set positioning column can be directly docked with the mounting hole of the three-dimensional flexible platform, and then the connecting tube is docked with the positioning column. The connecting tube and the positioning column are fixed by the fixing structure, so that the fixture can be fixed on the three-dimensional flexible processing platform, which is convenient for operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of a large-span refined steel truss structure of the present invention.

[0019] Figure 2 It is a schematic diagram of a sheet truss structure of a large-span refined steel truss structure of the present invention.

[0020] Figure 3 It is a schematic diagram of the sheet truss assembly structure of a large-span refined steel truss structure of the present invention.

[0021] Figure 4 This is the first schematic diagram of a fixture structure of a large-span fine steel truss structure of the present invention.

[0022] Figure 5 This is a second schematic diagram of a fixture structure of a large-span fine steel truss structure of the present invention.

[0023] Figure 6 The figure is a schematic diagram of a clamping plate installation structure of a large-span fine steel truss structure of the present invention.

[0024] Figure 7 It is a schematic diagram of the installation structure of the first linkage plate and the second linkage plate of a large-span refined steel truss structure of the present invention.

[0025] Figure 8 This is a schematic diagram of the installation structure of an adjustment tube of a large-span refined steel truss structure of the present invention.

[0026] Fig. 9 This is a first schematic diagram of a fixed structure of a large-span refined steel truss structure of the present invention.

[0027] Fig.10 This is a second schematic diagram of a fixed structure of a large-span refined steel truss structure of the present invention.

[0028] In the figure: 1-outer chord, 2-inner chord, 3-reinforced rib, 4-insert plate, 5-insert core, 6-positioning hole, 7-first key-shaped hole, 8-second key-shaped hole, 9-third key-shaped hole, 10-clamp, 11-first connecting plate, 12-second connecting plate, 13-mounting frame, 14-clamping plate, 15-mounting rod, 16-clamping spring, 17-sliding groove, 18-connecting pin, 19-swinging plate, 20-hinged rod, 21-first bevel gear, 22-second bevel gear, 2 3-installing shaft, 24-connecting plate, 25-first linkage plate, 26-second linkage plate, 27-fixing bolt, 28-adjusting cylinder, 29-distance scale, 30-adjusting screw, 31-adjusting knob, 32-sliding plate, 33-pointer, 34-connecting cylinder, 35-positioning column, 36-center rod, 37-control knob, 38-positioning groove, 39-positioning block, 40-matching plate, 41-push plate, 42-magnetic block, 43-magnetic strip, 44-rectangular groove, 46-rectangular mouth. DETAILED DESCRIPTION

[0029] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described in conjunction with the accompanying drawings, but the present invention is not limited to these embodiments.

[0030] like Figure 1-10 As shown, the present invention provides a large-span exquisite steel truss structure, including a plurality of sheet trusses that can be assembled with each other, the sheet trusses including an outer chord 1, an inner chord 2 and a stiffened rib 3, and clamps 10 with adjustable spacing are respectively installed on the lower sides of two adjacent sheet trusses; the outer chord 1 and the inner chord 2 are respectively clamped and limited by the clamps 10 to facilitate welding; the clamp 10 includes a mounting frame 13 and clamping plates 14 respectively slidably connected to both sides of the upper end of the mounting frame 13, the two clamping plates 14 can respectively move along the length direction of the clamping plates 14, and the outer sides of the two corresponding clamping plates 14 are respectively fixedly connected with clamping springs 16, and the outer ends of the clamping springs 16 are respectively fixedly connected to the mounting frame 13; the lower ends of the mounting frame 13 are respectively fixedly connected with connecting tubes 34, the lower sides of the connecting tubes 34 are connected with positioning columns 35, and the interior of the connecting tubes 34 is installed with a fixing structure that engages with the positioning columns 35.

[0031] When in use, the device uses a three-dimensional flexible processing platform to splice and assemble the sheet trusses to achieve the force requirements of a large span space. During welding, the clamp 10 is used to clamp and fix them to avoid welding deformation. During clamping and fixing, the inner side of the upper end of the clamping plate 14 is respectively provided with an inclined surface toward the outside. When clamping the outer chord 1 and the inner chord 2, the outer chord 1 or the inner chord 2 can be directly pressed downward through the upper ends of the two clamping plates 14. Under the action of the inclined surface, the two clamping plates 14 are forced to move outward and squeeze the clamping spring 16. When the outer chord 1 or the inner chord 2 is located between the two clamping plates 14, the two clamping plates 14 are pushed by the clamping spring 16 to reset and realize clamping and fixing. In order to facilitate the installation of the fixture 10 on the three-dimensional flexible processing platform, the set positioning column 35 can be directly connected to the mounting hole of the three-dimensional flexible platform, and then the connecting tube 34 is connected to the positioning column 35. The connecting tube 34 and the positioning column 35 are fixed by the fixing structure, so that the fixture 10 can be fixed on the three-dimensional flexible processing platform for convenient operation.

[0032] The front of the outer chord rod 1 and the inner chord rod 2 are respectively fixedly connected with a plug plate 4 and a plug core 5. The rear ends of the outer chord rod 1 and the inner chord rod 2 are respectively provided with sockets that can be engaged with the plug plate 4 and the plug core 5. When assembling, the adjacent plug plates 4 and the plug core 5 are respectively inserted into the corresponding sockets. The upper ends of the plug plates 4 and the plug core 5 are respectively provided with positioning holes 6 and first key-shaped holes 7 downwardly. The rear sides of the upper ends of the outer chord rod 1 and the inner chord rod 2 are respectively provided with third key-shaped holes 9 and second key-shaped holes 8. When the plug plates 4 and the plug core 5 are respectively inserted into the plugs, the plug plates 4 and the plug core 5 are respectively provided with positioning holes 6 and first key-shaped holes 7 downwardly. The rear positioning hole 6 and the first key-shaped hole 7 in the mouth correspond to the third key-shaped hole 9 and the second key-shaped hole 8 respectively. Rectangular openings 46 are respectively opened on the right sides of the rear ends of the outer chord 1 and the inner chord 2. When the sheet trusses are butt-jointed at right angles, the plug plate 4 and the plug core 5 can be respectively inserted into the corresponding rectangular openings 46. After insertion, the rear positioning hole 6 and the first key-shaped hole 7 can also correspond to the third key-shaped hole 9 and the second key-shaped hole 8, which is convenient for butt-jointing by inserting bolts and fixing by nuts, thereby improving the convenience during assembly and improving the stability and bearing capacity after installation.

[0033] The first connecting plate 11 and the second connecting plate 12 are fixedly connected between the two corresponding front and rear installation frames 13, respectively. The front end of the first connecting plate 11 is provided with a connecting groove toward the rear side. The first connecting plate 11 is slidably connected inside the connecting groove. The first connecting plate 11 and the second connecting plate 12 are slidably connected through the connecting groove, which facilitates the adjustment of the distance between the two corresponding front and rear clamps 10, and can be adjusted according to the length of the truss.

[0034] An adjusting cylinder 28 and an adjusting screw 30 are respectively arranged between the two corresponding installation frames 13 on the left and right. One end of the adjusting screw 30 corresponding to the adjusting cylinder 28 is threadedly connected to the inside of the adjusting cylinder 28, and the other end of the adjusting cylinder 28 is fixedly connected to the corresponding installation frame 13. The other end of the adjusting screw 30 is fixedly connected with an adjusting knob, and the adjusting knob is rotatably connected to the corresponding installation frame 13. By rotating the adjusting knob, the adjusting screw 30 can be driven to rotate inside the adjusting cylinder 28, and the distance between the outer chord 1 and the inner chord 2 can be adjusted under the action of the threaded connection, which is convenient for welding the reinforced rib 3.

[0035] The surface of the adjusting cylinder 28 is axially provided with a strip opening, and the interior of the adjusting cylinder 28 is axially slidably connected with a sliding plate 32, and the sliding plate 32 is rotatably connected to one end of the adjusting screw 30 entering the adjusting cylinder 28, and the circumferential surface of the sliding plate 32 is fixedly connected with a connecting block, and the connecting block is slidably connected to the strip opening, and the outer ends of the connecting frames are respectively fixedly connected with pointers 33, and the pointer 33 is slidably connected to the surface of the adjusting cylinder 28, and the surface of the adjusting cylinder 28 is axially provided with a distance scale 29 that cooperates with the pointer 33. When the adjusting screw 30 rotates, the axial movement inside the adjusting cylinder 28 is realized under the action of the threaded connection, and the sliding plate 32 can be driven to move axially inside the adjusting cylinder 28. When moving, the pointer 33 can be driven to slide on the surface of the adjusting cylinder 28, and the distance scale 29 indicated by the pointer 33 is convenient for the user to know the moving distance, so as to facilitate the accurate adjustment of the outer chord 1 and the inner chord 2 to a distance equal to the length of the stiffened rib 3, thereby improving the accuracy of the stiffened rib 3 during welding.

[0036] The front and rear sides of the upper end of the mounting frame 13 are respectively fixedly connected with mounting rods 15, and the clamping plates 14 are respectively slidably connected with the mounting rods 15, and the clamping springs 16 are respectively sleeved on the surfaces of the mounting rods 15. The lower ends of the clamping plates 14 are respectively fixedly connected with connecting pins 18. The middle part of the upper end of the mounting frame 13 is respectively provided with sliding grooves 17 along the length direction to the outside, and the lower ends of the connecting pins 18 extend to the inner side of the mounting frame 13 through the sliding grooves 17. The inner side of the mounting frame 13 is rotatably connected with a swing plate 19, and the two ends of the swing plate 19 are respectively hinged with hinge rods 20, and the other ends of the hinge rods 20 are respectively hinged with the connecting pins 18. By controlling the swing plate 19 to swing, the two clamping plates 14 can be driven to move outward to facilitate the removal of the outer chord rod 1 and the inner chord rod 2. When in use, the swing plate 19 is controlled to swing, and the outer side of the clamping plate 14 can be pushed to move under the linkage of the two hinge rods 20, and the outer side chord rod 1 and the inner chord rod 2 are no longer clamped and fixed.

[0037] The lower ends of the swing plates 19 are respectively fixedly connected with the first bevel gears 21, the lower sides of the first bevel gears 21 are respectively meshed with the second bevel gears 22, the middle parts of the second bevel gears 22 are respectively fixedly connected with the mounting shafts 23, the mounting shafts 23 are respectively rotatably connected with the mounting frames 13, and the ends of the mounting shafts 23 away from the second bevel gears 22 are respectively fixedly connected with the connecting plates 24, the lower ends of the two corresponding front and rear linkage plates are respectively hinged with the first linkage plate 25 and the second linkage plate 26, the ends of the second linkage plate 26 and the first linkage plate 25 corresponding to each other are respectively provided with docking grooves in the opposite direction away from the first linkage plate 25, a part of the second linkage plate 26 is slidably connected in the docking groove, and the outer end surfaces of the first linkage plate 25 are respectively threadedly connected with fixing screws The bolt 27, the fixing bolt 27 is connected to the docking groove and one end of the fixing bolt 27 located inside the docking groove is pressed against the surface of the second linkage plate 26. The sliding connection of the first linkage plate 25 and the second linkage plate 26 facilitates the adjustment of the spacing between the front and rear clamps 10. The first linkage plate 25 and the second linkage plate 26 can be fixed by the fixing bolt 27, which is convenient for use. The first linkage plate 25 and the second linkage plate 26 can swing synchronously when fixed, and the mounting shaft 23 is driven to rotate synchronously during the synchronous swinging. When the mounting shaft 23 rotates, the swing plate 19 can be driven to swing through the meshing of the first bevel gear 21 and the second bevel gear 22, thereby achieving the effect of synchronously controlling the clamping plate 14 to move outward, which is convenient for users to operate.

[0038] The fixing structure includes positioning grooves 38 provided on the corresponding two sides of the upper side of the surface of the positioning column 35, and mounting grooves are provided on the corresponding two sides of the upper side of the connecting tube 34. Positioning blocks 39 that can move along the radial direction of the connecting tube 34 are slidably connected to the inside of the mounting grooves. The corresponding ends of the positioning blocks 39 are fixedly connected to magnetic strips 43, and the inner walls of the positioning grooves 38 are fixedly connected to magnetic blocks 42. When the positioning blocks 39 correspond to the positioning grooves 38, the positioning blocks 39 can be driven into the positioning grooves 38 under the attraction of the magnetic blocks 42 and the magnetic strips 43. When the positioning blocks 39 enter the positioning grooves, the magnetic blocks 42 and the magnetic strips 43 are attracted to the positioning blocks 39. After the connecting tube 34 is inserted into the positioning groove 38, the connecting tube 34 cannot be separated from the positioning column 35, so that the clamp 10 is fixed. The upper end of the positioning column 35 is provided with a center hole downward, and a center rod 36 is rotatably connected inside the center hole. The lower end of the center rod 36 is fixedly connected to a control knob 37. Rectangular openings are respectively provided on both sides of the bottom of the positioning column 35, and the control knob 37 is exposed through the rectangular openings for the convenience of the user to rotate. The two sides corresponding to the upper side of the surface of the center rod 36 are respectively fixedly connected to the dial plates 41, and the upper ends of the positioning blocks 39 are respectively fixedly connected to the matching plates 40, and the inner ends of the matching plates 40 are respectively provided with The rectangular groove 44, when the center rod 36 rotates, the paddle plate 41 can push the matching plate 40 to move outward, so that the positioning block 39 is separated from the positioning groove 38, so that the positioning tube can move upward to separate from the positioning column 35, so that the clamp 10 can be disassembled, and when the paddle plate 41 rotates to push the positioning block 39 to move outward, the paddle plate 41 can be placed in the rectangular groove 44 to prevent the positioning block 39 from moving inward again under magnetic adsorption. A groove is provided on the surface of the center rod 36, and a torsion spring is sleeved on the inner side of the groove. One end of the torsion spring is fixedly connected to the center rod 36, and the other end of the torsion spring is connected to the center hole The inner wall is fixedly connected, and when the center rod 36 is rotated, the torsion spring is twisted to store force. When the positioning cylinder is separated from the positioning column 35, the control knob 37 is released, and the center rod 36 is reset under the action of the torsion spring, which is convenient for operation; the inner sides of the lower ends of the positioning blocks 39 are respectively inclined to the upper side. When the positioning block 39 slides out of the mounting groove and the positioning cylinder is installed on the positioning column 35 from top to bottom, the top end of the positioning column 35 presses against the inclined structure of the lower end of the positioning block 39, which can make the positioning block 39 move outward, and will not prevent the positioning cylinder from being installed on the surface of the positioning column 35, and will not affect the normal use of the device.

[0039] A method for preparing a large-span fine steel truss structure mainly comprises an inner chord, a reinforced rib plate 3, and an outer chord to form a sheet truss. First, the truss original plate is cut by laser, the cross section is grooved, and after being straightened, it is assembled and spot welded on a three-dimensional flexible platform, and is fully welded after being limited and fixed by a clamp 10. After the inner chord and the outer chord are fully welded, they are straightened for a second time, and the chord is placed flat on the working platform, and the reinforced rib plate 3 is welded. Stress deformation and expansion deformation are released by symmetrical welding and intermittent welding. The length span is carried out by three-section splicing, and the internal plug plate 4 and the plug are inserted. The core 5 is inserted into the socket, and a limit clamp 10 is set on the outside to prevent deformation during splicing. The surface is sandblasted and polished, and then primer and mid-coat are applied. After acceptance, the next step is carried out. The present invention solves the accuracy problem of delicate steel trusses in ultra-long spans. Laser cutting is used to improve the processing accuracy of the plates. Assembly and welding are carried out on a three-dimensional flexible working platform. Assembly deformation and welding stress deformation are effectively controlled. Robot welding is used to ensure straight and smooth welding. The above measures and methods can ensure that the accuracy of the truss straightness, section distortion, and section R angle meet the design requirements.

[0040] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A large-span refined steel truss structure, characterized by: Comprising a plurality of sheet trusses capable of being assembled with each other, the sheet trusses comprising an outer chord (1), an inner chord (2) and a stiffening rib (3); A clamp (10) capable of adjusting the spacing is installed on the lower side of two adjacent sheet trusses; the outer chord (1) and the inner chord (2) are clamped and limited by the clamp (10) to facilitate welding; the clamp (10) includes a mounting frame (13) and clamping plates (14) respectively slidably connected to both sides of the upper end of the mounting frame (13); The two clamping plates (14) are respectively movable along the length direction of the mounting frame (13); the outer sides of the two corresponding clamping plates (14) are respectively fixedly connected with clamping springs (16); the outer ends of the clamping springs (16) are respectively fixedly connected with the mounting frame (13); the lower ends of the mounting frame (13) are respectively fixedly connected with connecting tubes (34); the lower sides of the connecting tubes (34) are connected with positioning columns (35); and the interior of the connecting tubes (34) is provided with a fixing structure engaged with the positioning columns (35); The fixing structure comprises positioning grooves (38) provided on two corresponding sides of the upper side of the surface of the positioning column (35); mounting grooves are provided on two corresponding sides of the upper side of the connecting tube (34); positioning blocks (39) are slidably connected to the inside of the mounting grooves and are capable of moving along the radial direction of the connecting tube (34); corresponding ends of the positioning blocks (39) are fixedly connected to magnetic strips (43); inner walls of the positioning grooves (38) are fixedly connected to magnetic blocks (42); when the positioning blocks (39) correspond to the positioning grooves (38), the positioning blocks (39) are driven into the positioning grooves (38) under the attraction of the magnetic blocks (42) and the magnetic strips (43); and the upper end of the positioning column (35) is provided with a downwardly extending magnetic strip. A center hole is provided, wherein a center rod (36) is rotatably connected to the interior of the center hole, a control knob (37) is fixedly connected to the lower end of the center rod (36), a dial plate (41) is fixedly connected to the two corresponding sides of the upper side of the surface of the center rod (36), the upper ends of the positioning blocks (39) are fixedly connected to matching plates (40), the inner ends of the matching plates (40) are respectively provided with rectangular grooves (44), when the center rod (36) rotates, the matching plates (40) are pushed to move outward by the dial plate (41), a groove is provided on the surface of the center rod (36), a torsion spring is sleeved on the inner side of the groove, one end of the torsion spring is fixedly connected to the center rod (36), and the other end of the torsion spring is fixedly connected to the inner wall of the center hole.

2. A large-span fine steel truss structure as claimed in claim 1, characterized in that: The front ends of the outer chord rod (1) and the inner chord rod (2) are respectively fixedly connected with a plug plate (4) and a plug core (5); the rear ends of the outer chord rod (1) and the inner chord rod (2) are respectively provided with sockets capable of respectively engaging with the plug plate (4) and the plug core (5); when assembling, adjacent plug plates (4) and plug cores (5) are respectively inserted into corresponding sockets; the upper ends of the plug plate (4) and the plug core (5) are respectively provided with a positioning hole (6) and a first key-shaped hole (7) facing downwards.

3. A large-span fine steel truss structure as claimed in claim 2, characterized in that: A third key-shaped hole (9) and a second key-shaped hole (8) are respectively provided on the rear side of the upper end of the surface of the outer chord rod (1) and the inner chord rod (2); when the plug plate (4) and the plug core (5) are respectively inserted into the socket, the positioning hole (6) and the first key-shaped hole (7) correspond to the third key-shaped hole (9) and the second key-shaped hole (8); and a rectangular opening (46) is respectively provided on the right side of the rear end of the outer chord rod (1) and the inner chord rod (2); when the sheet trusses are butt-jointed at right angles, the plug plate (4) and the plug core (5) can be respectively inserted into the corresponding rectangular openings (46).

4. A large-span fine steel truss structure as claimed in claim 3, characterized in that: A first connecting plate (11) and a second connecting plate (12) are respectively fixedly connected between two correspondingly arranged front and rear mounting frames (13); a connecting groove is provided at the front end of the first connecting plate (11) toward the rear, and the second connecting plate (12) is slidably connected inside the connecting groove.

5. A large-span fine steel truss structure as claimed in claim 4, characterized in that: An adjusting cylinder (28) and an adjusting screw (30) are respectively arranged between the two correspondingly arranged left and right mounting frames (13); one end of the adjusting screw (30) corresponding to the adjusting cylinder (28) is threadedly connected to the inside of the adjusting cylinder (28); the other end of the adjusting cylinder (28) is fixedly connected to the corresponding mounting frame (13); the other end of the adjusting screw (30) is respectively fixedly connected to an adjusting knob; and the adjusting knob is respectively rotatably connected to the corresponding mounting frame (13).

6. A large-span fine steel truss structure as claimed in claim 5, characterized in that: The surface of the adjusting cylinder (28) is provided with a strip-shaped opening in the axial direction, and a sliding plate (32) is slidably connected to the inside of the adjusting cylinder (28) in the axial direction. The sliding plate (32) is rotatably connected to one end of the adjusting screw (30) entering the adjusting cylinder (28). A connecting block is fixedly connected to the circumferential surface of the sliding plate (32), and the connecting block is slidably connected to the strip-shaped opening. Pointers (33) are fixedly connected to the outer ends of the connecting blocks, and the pointers (33) are slidably connected to the surface of the adjusting cylinder (28). A distance scale (29) matching the pointer (33) is axially provided on the surface of the adjusting cylinder (28).

7. The method for preparing a large-span fine steel truss structure according to claim 6, characterized in that: The following steps are involved: S1: The outer chord (1), the inner chord (2) and the stiffened rib plate (3) are cut from original plates by laser, the cross-sections are grooved, and after being straightened, they are assembled and spot welded and fixed, and after being limited and fixed by a clamp (10), they are fully welded. After the outer chord (1) and the inner chord (2) are fully welded, they are straightened for a second time; S2: placing the outer chord (1) and the inner chord (2) flat on a working platform, welding the reinforced ribs (3), and releasing stress deformation and expansion deformation by symmetrical welding and intermittent welding; S3: The length span is achieved by splicing in three sections, inserting the plug plate (4) and the plug core (5) into the corresponding sockets respectively, and the surfaces are clamped and fixed by a clamp (10) to prevent splicing deformation; S4: After the surface is sandblasted and polished, it is primed and mid-coated. After passing the inspection, the next process is carried out.

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