Free-form surface ceiling skin structure and construction method thereof

Abstract

According to the free-form surface ceiling skin structure and the construction method thereof, the problem that an existing double-curved-surface ceiling skin is large in machining and mounting difficulty is solved. A plurality of main keels are connected to form a main frame, vertical adjusting devices are arranged along installation reference lines of secondary keels and connected to the main frame, transverse adjusting devices are connected between every two adjacent secondary keels, prefabricated stretch-bent secondary keels are connected to the bottom ends of the vertical adjusting devices and spliced into a secondary frame, and a suspended ceiling panel is laid and connected to the bottom of the secondary frame. The construction method comprises the steps that the main keels are spliced into the main frame, the vertical adjusting devices are arranged in the extending direction of the installation reference line, the top ends of the vertical adjusting devices are connected to the main keels, the transverse adjusting devices are arranged between the secondary keels, and the secondary keels are continuously spliced to the bottom ends of the vertical adjusting devices along the installation reference line to form the secondary frame; the bottom surface of the sub-frame is consistent with the free-form surface suspended ceiling in shape, and the suspended ceiling panel is gradually paved on the bottom skin of the sub-frame for forming.

Description

Technical Field

[0001] The invention relates to the technical field of building decoration construction, and in particular to a free-form surface ceiling skin structure and a construction method thereof. Background Art

[0002] The main building of Jiaxing Nanhu Future Plaza adopts a large-span special-shaped space steel structure arch truss system with a white ceramic tile curved curtain wall roof, combined with the greening of each layer of the terraced space, to form a patchwork of buildings. Among them, the inner side of some roof ceilings is a glass curtain wall, and the outer side is the roof eaves. The intersection of the two ends of the roof ceiling and the roof eaves and glass curtain wall is a free-changing curve, and the ceiling skin is a complex hyperbolic shape. If metal panels are used to make the ceiling skin, the metal panel processing technology is complicated and the processing accuracy requirements are high. There are problems such as difficulty in on-site installation and obvious step differences between panels, which increases the difficulty of roof ceiling construction. Summary of the invention

[0003] The existing use of metal panels to construct hyperbolic ceiling skins has the problems of complex processing technology, great installation difficulty, and difficulty in ensuring construction quality. The purpose of the present invention is to provide a free-form surface ceiling skin structure and a construction method thereof.

[0004] The technical solution adopted by the present invention to solve its technical problems is: a free-form surface ceiling skin structure, which includes: a main frame, a secondary frame, a lateral adjustment device, a vertical adjustment device and a ceiling panel, a plurality of main keels are crisscrossed and connected to form a main frame, the main frame is connected to the main beam of the building structure through a vertically arranged hanger, a plurality of vertical adjustment devices are vertically and spaced apart along the installation reference line of the secondary keels and connected to the main frame, a plurality of lateral adjustment devices are horizontally and spaced apart and connected between two adjacent secondary keels, a plurality of prefabricated bent secondary keels are connected to the bottom end of the vertical adjustment device and assembled into a secondary frame, and the bottom surface of the secondary frame is consistent with the shape of the free-form surface ceiling, and the ceiling panel is paved and connected to the bottom of the secondary frame.

[0005] The free-form surface ceiling skin structure of the present invention comprises a main frame formed by connecting a plurality of main keels, a secondary frame formed by connecting a plurality of secondary keels, a vertical adjustment device vertically arranged and connected between the main frame and the secondary frame, a lateral adjustment device connected between two adjacent secondary keels in the secondary frame, and a ceiling panel connected to the bottom of the secondary frame; since the secondary keels are prefabricated and bent according to the curvature of two intersecting curves between the three-dimensional model of the free-form surface ceiling and the facade structures on both sides, there is no need to perform a bending process on the main keels, so that the bent secondary keels can be stably connected to the main frame, thereby reducing The difficulty of keel processing and installation is reduced; the vertical adjustment device is arranged along the installation reference line of the secondary keel and connected between the main frame and the secondary frame, which is convenient for construction personnel to adjust the connection node position of the secondary keel and the vertical adjustment device; the transverse adjustment device is arranged laterally and spaced between two adjacent secondary keels, which can adapt to the horizontal deformation of the structure; the free-form surface ceiling skin structure arranges the vertical adjustment device and the transverse adjustment device at appropriate positions in the ceiling frame, so that the ceiling frame can adapt to the free-form surface ceiling shape, thereby improving the construction efficiency and construction quality of the free-form surface ceiling.

[0006] Furthermore, an additional main keel is added to the main frame, and the additional main keel is connected to the adjacent main keels on both sides thereof, and a vertical adjustment device is connected between the additional main keel and the secondary keel.

[0007] Furthermore, the lateral adjustment device includes an angle code and a connecting rod, one side of the angle code is connected to the secondary keel, and the other side of the angle code and the end of the connecting rod are provided with oblong holes corresponding in position and number, the connecting rod and the angle code are locked and fixed by bolts passing through the oblong holes, and the other end of the connecting rod is connected to the adjacent secondary keel.

[0008] Furthermore, it also includes a plurality of connectors, which are arranged at the joints of two adjacent ceiling panels, the cross section of the connector is L-shaped, one side of the connector is connected to the secondary keel, and the other side is threadedly connected to the ceiling panel.

[0009] Furthermore, the ceiling panel adopts a flat cement fiber board, and the distance between two adjacent secondary purlins is 1 / n of the width of the cement fiber board, where n is a natural number greater than 1. After the cement fiber board is laid on the bottom of the secondary frame along the extension direction of the installation reference line, the cement fiber board is fixed to the secondary purlin with flat-head self-tapping screws.

[0010] In addition, the present invention also provides a construction method of a free-form surface ceiling skin structure, the steps are as follows:

[0011] S1: Determine two intersecting curves between the free-form surface ceiling and the facade structures on both sides according to the three-dimensional model of the main structure of the building, select corresponding positioning points on the two intersecting curves, use the intersection line between the longitudinal section where the two corresponding positioning points are located and the three-dimensional model of the free-form surface ceiling as the installation reference line of the secondary keel, determine the position of the connection node between the vertical adjustment device and the secondary keel according to the installation reference line, and bend the prefabricated secondary keel according to the curvature of the two intersecting curves;

[0012] S2: Multiple main keels are arranged crisscross and assembled into a main frame, the main frame is connected to the main beam of the building structure through a vertically arranged hanger, multiple vertical adjustment devices are arranged vertically and at intervals along the extension direction of the installation reference line, and the top of the vertical adjustment device is connected to the main keel, multiple horizontal adjustment devices are arranged horizontally and at intervals between the secondary keels, and multiple secondary keels are continuously spliced ​​along the extension direction of the installation reference line and connected to the bottom of the vertical adjustment device in turn, and this is repeated until a secondary frame of a free-form surface is formed, and the bottom surface of the secondary frame is consistent with the shape of the free-form surface ceiling;

[0013] S3: gradually lay the ceiling panels on the bottom of the secondary frame from the inside to the outside, fix the ceiling panels to the secondary keel, use caulking agent and seam tape to close the joints between two adjacent ceiling panels, level and make the joints of the ceiling panels transition smoothly, and spray the paint evenly on the outer surface of the ceiling panels.

[0014] The construction method of the free-form surface ceiling skin structure of the present invention comprises the following steps: first, determining the intersection curve between the free-form surface ceiling and its adjacent facade structure according to the three-dimensional model of the main structure of the building, bending the prefabricated secondary keels according to the curvature of the two intersection curves, selecting corresponding positioning points on the two intersection curves at equal intervals, and taking the intersection line between the longitudinal section where the corresponding two positioning points are located and the three-dimensional model of the free-form surface ceiling as the installation reference line of the secondary keels; arranging and assembling a plurality of main keels in a criss-cross manner into a main frame, arranging a plurality of vertical adjustment devices vertically and at intervals along the extension direction of the installation reference line, and the top ends of the vertical adjustment devices are connected to the main keels, arranging a plurality of horizontal adjustment devices horizontally and at intervals between the secondary keels, and continuously splicing the plurality of secondary keels along the extension direction of the installation reference line and sequentially connecting them to the bottom ends of the vertical adjustment devices, and repeating this process until the secondary keels are assembled. The frame is formed by laying the ceiling panel on the bottom of the secondary frame from the inside to the outside. The construction method uses the three-dimensional model of the main structure of the building to accurately obtain the prefabrication bending data of the secondary keel and the installation reference line of the secondary keel. A vertical adjustment device is added along the installation reference line in the ceiling keel frame to adapt to the different installation heights of the secondary keel. A horizontal adjustment device is added between two adjacent secondary keels to adapt to the horizontal deformation of the structure. The main keel and the ceiling panel do not need to be prefabricated into a curved surface, which reduces the difficulty of component processing and installation. Moreover, by arranging vertical and horizontal adjustment devices in the keel frame, the vertical and horizontal positions of the secondary keel can be flexibly adjusted according to installation needs, thereby realizing the shape design of the free-form surface ceiling and improving the construction efficiency and quality of the free-form surface ceiling.

[0015] Furthermore, in step S2, an additional main keel is added to the main frame, the additional main keel is connected to the adjacent main keels on both sides thereof, and a vertical adjustment device is connected between the additional main keel and the secondary keel.

[0016] Furthermore, in step S2, a connecting piece is added at the joint between two adjacent ceiling panels, the cross section of the connecting piece is L-shaped, one side of the connecting piece is connected to the secondary keel, and the other side is threadedly connected to the ceiling panel, the joint between the two adjacent ceiling panels is filled with caulking material, and the outside is sealed with a seam tape.

[0017] Furthermore, in step S3, the ceiling panel adopts a flat cement fiber board, and the distance between two adjacent secondary purlins is 1 / n of the width of the ceiling panel, where n is a natural number greater than 1. After the cement fiber board is laid on the bottom of the secondary frame along the extension direction of the installation reference line, the two ends and the middle of the cement fiber board are fixed to the secondary purlins with flat-head self-tapping screws. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of an embodiment of a free-form surface ceiling skin structure of the present invention;

[0019] Figure 2 for Figure 1 A partial enlarged view of part A;

[0020] Figure 3 This is a schematic diagram of the structure of a connecting member in one embodiment of the present invention;

[0021] Figure 4 for Figure 3 A partial enlarged view of part B.

[0022] The numbers in the figure are as follows:

[0023] Main beam 1; main keel 11; suspension rod 12; sleeve core 14; vertical adjustment device 15; secondary keel 16; lateral adjustment device 17; angle code 171; connecting rod 172; oblong hole 173; connecting piece 18; ceiling panel 20; caulking agent 21; joint tape 24. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. For the convenience of description, the "upper" and "lower" described below are consistent with the upper and lower directions of the drawings, but this cannot be a limitation of the technical solution of the present invention.

[0025] This embodiment takes the construction of part of the roof ceiling of the main building of Jiaxing Nanhu Future Plaza as an example. The inner side of the roof ceiling is a glass curtain wall, and the outer side is the roof eaves. Figures 1 to 4 The free-form surface ceiling skin structure of the present invention is described, which includes: a main frame, a secondary frame, a lateral adjustment device 17, a vertical adjustment device 15 and a ceiling panel 20, a plurality of main purlins 11 are criss-crossed and connected through a sleeve core 14 to form a main frame, the main frame is connected to the main beam 1 of the building structure through a vertically arranged hanger 12, a plurality of vertical adjustment devices 15 are vertically and spaced apart and connected to the main frame along the installation reference line of the secondary purlins 16, a plurality of lateral adjustment devices 17 are horizontally and spaced apart and connected between two adjacent secondary purlins 16, a plurality of prefabricated bent secondary purlins 16 are connected to the bottom end of the vertical adjustment device 15 according to a preset position and assembled into a secondary frame, and the bottom surface of the secondary frame is consistent with the shape of the free-form surface ceiling, and the ceiling panel 20 is laid and connected to the bottom of the secondary frame.

[0026] The free-form surface ceiling skin structure of the present invention comprises a main frame formed by connecting a plurality of main keels 11, a secondary frame formed by connecting a plurality of secondary keels 16, a vertical adjustment device 15 vertically arranged and connected between the main frame and the secondary frame, a lateral adjustment device 17 connected between two adjacent secondary keels 16 in the secondary frame, and a ceiling panel 20 connected to the bottom of the secondary frame; since the secondary keels 16 are prefabricated and bent according to the curvature of two intersecting curves between the three-dimensional model of the free-form surface ceiling and the facade structures on both sides, there is no need to perform a bending process on the main keels 11, so that the bent secondary keels 16 can be stably connected to the main frame. The difficulty of keel processing and installation is reduced; the vertical adjustment device 15 is arranged along the installation reference line of the secondary keel 16 and connected between the main frame and the secondary frame, which is convenient for construction personnel to adjust the connection node position of the secondary keel 16 and the vertical adjustment device 15; the transverse adjustment device 17 is arranged laterally and spaced between two adjacent secondary keels 16, which can adapt to the horizontal deformation of the structure; the free-form surface ceiling skin structure arranges the vertical adjustment device 15 and the transverse adjustment device 17 at appropriate positions in the ceiling frame, so that the ceiling frame can adapt to the free-form surface ceiling shape, thereby improving the construction efficiency and construction quality of the free-form surface ceiling.

[0027] As the spans on both sides of the free-form surface ceiling are too large, in order to reduce the span of the secondary keel 16, an additional main keel 11 (not shown in the figure) is added to the main frame of the free-form surface ceiling. The additional main keel 11 is connected to the adjacent main keels 11 on both sides thereof, and a vertical adjustment device 15 is connected between the additional main keel 11 and the secondary keel 16. The additional main keel 11 does not need to be prefabricated by stretching and bending, which reduces the workload of prefabricating and stretching the keel and facilitates installation and construction.

[0028] like Figure 1 and Figure 2 As shown, the lateral adjustment device 17 includes an angle bracket 171 and a connecting rod 172. One side of the angle bracket 171 is connected to the secondary keel 16. The other side of the angle bracket 171 and the end of the connecting rod 172 are provided with oblong holes 173 corresponding in position and number. The connecting rod 172 and the angle bracket 171 are locked and fixed by bolts passing through the oblong holes 173. The other end of the connecting rod 172 is connected to the adjacent secondary keel 16. The oblong holes 173 can provide a margin of movement between the angle bracket 171 and the connecting rod 172, so that the secondary frame can absorb structural deformation and temperature deformation. In this embodiment, along the extension direction of the installation reference line of the secondary keel 16, a lateral adjustment device 17 is set every 9 meters in the secondary frame.

[0029] like Figure 1 and Figure 2As shown, the vertical adjustment device 15 of this embodiment is made of galvanized square steel pipe, and the two ends of the vertical adjustment device 15 are respectively welded to the main keel 11 and the secondary keel 16. In addition, the vertical adjustment device 15 can also adopt a retractable structure with a screw and a sleeve threaded connection, so that the length adjustment of the vertical adjustment device 15 is more convenient and quick, and the technical solution of the present invention can be realized.

[0030] like Figure 3 and Figure 4 As shown, the free-form surface ceiling skin structure further includes a plurality of connectors 18. When two adjacent ceiling panels 20 cannot be overlapped on the secondary keel 16 due to the large size of the joint at the curved surface deflection, a connector 18 is provided at the joint of the two adjacent ceiling panels 20. The cross section of the connector 18 is L-shaped, one side of the connector 18 is connected to the secondary keel 16, and the other side is threadedly connected to the ceiling panel 20. The provision of the connecting plate achieves the effect of indirectly widening the width of the secondary keel 16, so that the ceiling panel 20 can be threadedly connected to the secondary frame, and a stable connection between the ceiling panels 20 and the secondary frame on both sides of the joint is achieved.

[0031] The ceiling panel 20 of this embodiment adopts a flat cement fiber board, which does not need to be prefabricated into a curved shape. The cement fiber board has high strength and can withstand large loads and pressures. The toughness of the cement fiber board itself is used to fit and connect to the curved keel frame to achieve the installation and construction of the free-form surface ceiling, reducing the difficulty of processing and installation of the ceiling decorative panel. In this embodiment, the spacing between two adjacent secondary keels 16 is 1 / n of the width of the cement fiber board, where n is a natural number greater than 1. This embodiment adopts a commercially available cement fiber board with a board width of 2.1m×1.2m. The spacing between the two secondary keels 16 is 0.4m, and the width of the cement fiber board is 3 times the spacing between the secondary keels 16. After the cement fiber board is laid on the bottom of the secondary frame along the extension direction of the installation reference line, the two ends and the middle of the cement fiber board are fixed to the secondary keel 16 with flat-head self-tapping screws, which reduces the workload of cutting and assembling the cement fiber board and improves construction efficiency.

[0032] Combination Figures 1 to 4 The construction method of the free-form surface ceiling skin structure of the present invention is described, and the specific steps are as follows:

[0033] S1: Determine two intersecting curves between the free-form surface ceiling and the inner glass curtain wall and the outer roof eaves according to the three-dimensional model of the main structure of the building, select corresponding positioning points on the two intersecting curves, and use the intersection line between the longitudinal section where the two corresponding positioning points are located and the three-dimensional model of the free-form surface ceiling as the installation reference line of the secondary keel 16. Determine the position of the connection node between the vertical adjustment device 15 and the secondary keel 16 according to the installation reference line, and use a bending machine to bend the prefabricated secondary keel 16 in the factory according to the curvature of the two intersecting curves;

[0034] S2: multiple main keels 11 are arranged in a crisscross pattern and assembled into a main frame, the main frame is connected to the main beam 1 of the building structure through a vertically arranged hanger 12, multiple vertical adjustment devices 15 are arranged vertically and at intervals along the extension direction of the installation reference line, and the top of the vertical adjustment device 15 is connected to the main keel 11, multiple horizontal adjustment devices 17 are arranged horizontally and at intervals between the secondary keels 16, and multiple secondary keels 16 are continuously spliced ​​along the extension direction of the installation reference line and connected to the bottom of the vertical adjustment device 15 in sequence, and this is repeated until the multiple linear keels arranged at intervals together form a free-form surface secondary frame, and the bottom surface of the secondary frame is consistent with the shape of the free-form surface ceiling;

[0035] S3: gradually lay the ceiling panel 20 on the bottom of the secondary frame from the inner glass curtain wall to the outer roof eaves, fix the ceiling panel 20 to the secondary keel 16 with flat head self-tapping screws, use filler 21 and seam tape 24 to close the joints between two adjacent ceiling panels 20, scrape two layers of putty on the whole to make the joints of the ceiling panels 20 transition smoothly, and use outdoor paint to evenly spray the outer surface of the ceiling panel 20.

[0036] The construction method of the free-form surface ceiling skin structure of the present invention comprises the following steps: first, determining the intersection curve between the free-form surface ceiling and its adjacent facade structure according to the three-dimensional model of the main structure of the building, bending the prefabricated secondary keels 16 according to the curvature of the two intersection curves, selecting corresponding positioning points on the two intersection curves at equal intervals, and taking the intersection line between the longitudinal section where the corresponding two positioning points are located and the three-dimensional model of the free-form surface ceiling as the installation reference line of the secondary keel 16; arranging and assembling a plurality of main keels 11 in a criss-cross manner into a main frame, arranging a plurality of vertical adjustment devices 15 vertically and at intervals along the extension direction of the installation reference line, and the top end of the vertical adjustment device 15 is connected to the main keel 11, and arranging a plurality of horizontal adjustment devices 17 horizontally and at intervals between the secondary keels 16, and continuously splicing the plurality of secondary keels 16 along the extension direction of the installation reference line and sequentially connecting them to the bottom end of the vertical adjustment device 15, and repeating this process until the secondary keels 16 are assembled. The frame is formed by laying the ceiling panel 20 on the bottom of the secondary frame from the inside to the outside. The construction method uses the three-dimensional model of the main structure of the building to accurately obtain the prefabrication bending data of the secondary keel 16 and the installation reference line of the secondary keel 16. A vertical adjustment device 15 is added along the installation reference line in the ceiling keel frame to adapt to the different installation heights of the secondary keel 16. A horizontal adjustment device 17 is added between two adjacent secondary keels 16 to adapt to the horizontal deformation of the structure. The main keel 11 and the ceiling panel 20 do not need to be prefabricated into a curved surface shape, which reduces the difficulty of component processing and installation. Moreover, by arranging vertical and horizontal adjustment devices in the keel frame, the vertical and horizontal positions of the secondary keel 16 can be flexibly adjusted according to installation needs, thereby realizing the shape design of the free-form surface ceiling and improving the construction efficiency and quality of the free-form surface ceiling.

[0037] Since the spans on both sides of the free-form surface ceiling are too large, in order to reduce the span of the secondary keel 16, in step S2, an additional main keel 11 is added to the main frame, the additional main keel 11 is connected to the adjacent main keels 11 on both sides thereof, and a vertical adjustment device 15 is connected between the additional main keel 11 and the secondary keel 16.

[0038] like Figure 3 and Figure 4 As shown, due to the limited width of the secondary keel 16, for the area where the adjacent ceiling panels 20 cannot be placed exactly on the secondary keel 16 due to the deflection of the curved surface, the secondary keel 16 is partially widened to ensure that the ceiling panels 20 in this area have enough space to be nailed and fixed. In the step S2, a connector 18 is added at the joint between two adjacent ceiling panels 20. The cross section of the connector 18 is L-shaped. One side of the connector 18 is connected to the secondary keel 16, and the other side is threadedly connected to the ceiling panel 20. The joint between the two adjacent ceiling panels 20 is filled with caulking material, and the outer side is sealed by a joint tape 24.

[0039] In the step S3, this embodiment uses a commercially available cement fiber board with a board width of 2.1m×1.2m. The secondary purlins 16 of the free-form surface ceiling are arranged at intervals of 0.4m. The multiple linear purlins arranged at intervals together constitute the secondary frame of the free-form surface. The width of the cement fiber board is 3 times the spacing of the secondary purlins 16. A marking line is made on the cement fiber board every 0.4m. The two ends of the cement fiber board are fixed to the secondary purlins 16 with flat-head self-tapping screws. Then, the middle part of the cement fiber board is also fixed to the secondary purlins 16 along the marking line with flat-head self-tapping screws to ensure the connection strength between the entire cement fiber board and the secondary purlins 16.

[0040] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of the claims.

Claims

1. A free-form surface ceiling skin structure, characterized in that: include: A main frame, a secondary frame, a lateral adjustment device, a vertical adjustment device and a ceiling panel, multiple main purlins are crisscrossed and connected to form a main frame, the main frame is connected to the main beam of the building structure through vertically arranged hangers, multiple vertical adjustment devices are vertically and spaced along the installation reference line of the secondary purlins and connected to the main frame, multiple lateral adjustment devices are horizontally and spaced and connected between two adjacent secondary purlins, multiple prefabricated bent secondary purlins are connected to the bottom end of the vertical adjustment device and assembled into a secondary frame, and the bottom surface of the secondary frame is consistent with the shape of the free-form surface ceiling, and the ceiling panel is laid and connected to the bottom of the secondary frame.

2. The free-form surface ceiling skin structure according to claim 1, characterized in that: An additional main keel is also added to the main frame, and the additional main keel is connected to the adjacent main keels on both sides thereof, and a vertical adjustment device is connected between the additional main keel and the secondary keel.

3. The free-form surface ceiling skin structure according to claim 1, characterized in that: The lateral adjustment device includes an angle code and a connecting rod. One side of the angle code is connected to the secondary keel, and the other side of the angle code and the end of the connecting rod are provided with oblong holes corresponding in position and number. The connecting rod and the angle code are locked and fixed by bolts passing through the oblong holes, and the other end of the connecting rod is connected to the adjacent secondary keel.

4. The free-form surface ceiling skin structure according to claim 1, characterized in that: It also includes a plurality of connectors, which are arranged at the joints of two adjacent ceiling panels. The cross section of the connector is L-shaped, one side of the connector is connected to the secondary keel, and the other side is threadedly connected to the ceiling panel.

5. The free-form surface ceiling skin structure according to claim 1, characterized in that: The ceiling panel adopts a flat cement fiber board, and the distance between two adjacent secondary purlins is 1 / n of the width of the cement fiber board, where n is a natural number greater than 1. After the cement fiber board is laid on the bottom of the secondary frame along the extension direction of the installation reference line, the cement fiber board is fixed to the secondary purlin with flat head self-tapping screws.

6. The construction method of the free-form surface ceiling skin structure according to any one of claims 1 to 5, characterized in that: Here are the steps: S1: Determine two intersecting curves between the free-form surface ceiling and the facade structures on both sides according to the three-dimensional model of the main structure of the building, select corresponding positioning points on the two intersecting curves, use the intersection line between the longitudinal section where the two corresponding positioning points are located and the three-dimensional model of the free-form surface ceiling as the installation reference line of the secondary keel, determine the position of the connection node between the vertical adjustment device and the secondary keel according to the installation reference line, and bend the prefabricated secondary keel according to the curvature of the two intersecting curves; S2: Multiple main keels are arranged crisscross and assembled into a main frame, the main frame is connected to the main beam of the building structure through a vertically arranged hanger, multiple vertical adjustment devices are arranged vertically and at intervals along the extension direction of the installation reference line, and the top of the vertical adjustment device is connected to the main keel, multiple horizontal adjustment devices are arranged horizontally and at intervals between the secondary keels, and multiple secondary keels are continuously spliced ​​along the extension direction of the installation reference line and connected to the bottom of the vertical adjustment device in turn, and this is repeated until a secondary frame of a free-form surface is formed, and the bottom surface of the secondary frame is consistent with the shape of the free-form surface ceiling; S3: gradually lay the ceiling panels on the bottom of the secondary frame from the inside to the outside, fix the ceiling panels to the secondary keel, use caulking agent and seam tape to close the joints between two adjacent ceiling panels, level and make the joints of the ceiling panels transition smoothly, and spray the paint evenly on the outer surface of the ceiling panels.

7. The construction method of the free-form surface ceiling skin structure according to claim 1, characterized in that: In step S2, an additional main keel is added to the main frame, the additional main keel is connected to the adjacent main keels on both sides thereof, and a vertical adjustment device is connected between the additional main keel and the secondary keel.

8. The construction method of the free-form surface ceiling skin structure according to claim 1, characterized in that: In step S2, a connector is added at the joint between two adjacent ceiling panels. The cross section of the connector is L-shaped. One side of the connector is connected to the secondary keel, and the other side is threadedly connected to the ceiling panel. The joint between the two adjacent ceiling panels is filled with caulking material, and the outside is sealed with a joint tape.

9. The construction method of the free-form surface ceiling skin structure according to claim 1, characterized in that: In step S3, the ceiling panel adopts a flat cement fiber board, and the distance between two adjacent secondary purlins is 1 / n of the width of the ceiling panel, where n is a natural number greater than 1. After the cement fiber board is laid on the bottom of the secondary frame along the extension direction of the installation reference line, the two ends and the middle of the cement fiber board are fixed to the secondary purlins with flat-head self-tapping screws.

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