A prefabricated box beam prestressed channel drilling device

Abstract

The present invention provides a prefabricated box girder prestressed duct drilling device that replaces the corrugated pipe commonly used in prefabricated box girder drilling. The prefabricated box girder prestressed duct drilling device includes a high-strength rubber pipe and several support units that provide internal support for the high-strength rubber pipe. The support units include a rotating device for transmitting torque and an opening and closing device for supporting the inner wall of the pipe. Slots in the rotating device and inner and outer shells in the opening and closing device provide simultaneous and effective support for the pipe in all directions. The support effect of the support units is unaffected by changes in the external ambient temperature. After the prestressed duct is formed, the entire device can be removed and reused.

Description

Technical Field

[0001] The invention belongs to the field of construction engineering, and in particular relates to a prefabricated box beam prestressed channel hole forming device. Background Art

[0002] During the construction of prefabricated box girders, pre-embedded corrugated pipes are commonly used to form channels for the prestressed steel strands. Corrugated pipes have thin walls and a certain strength, which can reduce the weight of the box girder. They are also resistant to high pressure and corrosion. While these pipes offer numerous advantages, their hollow interior can deform during concrete pouring. Localized pressure can cause cracks in the pipe walls, and moisture in these cracks can lead to corrosion of the steel strands, compromising the safety of the structure.

[0003] CN111906901B discloses a prestressed channel forming device for concrete structures, comprising a channel forming tube made of an elastic material, the outer periphery of which has grooves and protrusions arranged axially in sequence. Channel forming is achieved by injecting liquid into the tube. CN206607871U discloses a prestressed channel former, composed of a high-strength rubber outer layer and a lightweight electro-deformable metal segment within, with an airbag in the middle. The airbag is connected to an electronic air pump. After the linear shape is designed, the airbag is inflated. The curvature required by the design is checked through the electro-deformable metal segment, and then concrete is poured. Finally, the airbag is deflated and the former is withdrawn. Both of the above-mentioned forming devices can be removed after use. However, whether the internal mold is inflated or liquid is injected, the hole forming device may deform as a whole after being subjected to high pressure. At the same time, the density of air and liquid is easily affected by temperature. Changes in external temperature and temperature changes during pouring can affect the channel pouring process, potentially causing the formed channel linear shape to deviate from the designed channel linear shape. Summary of the Invention

[0004] The purpose of the present invention is to provide a prefabricated box girder prestressed channel hole forming device to solve the problem of overall deformation caused by the pressure of the inner mold and overcome the linear deviation caused by the change of the density of the inner mold filling medium due to temperature changes during the channel casting process.

[0005] To achieve the above object, the present invention adopts the following technical solution: a prefabricated box girder prestressed channel drilling device, comprising an outermost high-strength rubber pipe, wherein a plurality of interconnected support units are arranged inside the high-strength rubber pipe;

[0006] The support unit also includes an internal rotating device for transmitting torque and an external opening and closing device for support; the rotating device includes a main shaft and a secondary shaft arranged on the left and right sides of the main shaft, the right end of the left secondary shaft is fixed with a sleeve shaft A, the left half of the main shaft is provided with a thread, and the sleeve shaft A is spirally connected to the main shaft; the left end of the right secondary shaft is fixed with a sleeve shaft B, and the sleeve shaft B is fixedly connected to the main shaft; the secondary shaft is also connected in series with a fixed universal joint and a cross-shaped umbrella section along the axial direction from the outside to the inside, and the outer extension radius of the umbrella section gradually decreases from the outside to the inside along the axial direction; the outer extension of the umbrella section is provided with a slot hole, and the slot hole includes an oblique slot and a broken line slot, and the oblique slot or broken line slot is symmetrically arranged in the plane of the umbrella section;

[0007] The opening and closing device includes several sliding rods, an inner shell and an outer shell. The sliding rods are slidably connected to the slots, and the inner shell is fixed on the sliding rods connected to the folding grooves; the outer shell is fixed on the sliding rods connected to the inclined grooves, and the outer shell is overlapped by enveloping the inner shell through the flattened axial edges.

[0008] Preferably, the bending angle of the folding groove along the axial direction is smaller than the inclination angle of the inclined groove along the axial direction. The sleeve shaft B rotates at a uniform speed to drive the slide rod to move along the groove. The speed of the slide rod moving radially outward in the folding groove is first slow and then fast, and the speed of movement along the inclined groove is kept uniform. In this way, the rising processes of the inner and outer shells do not interfere with each other, and can open completely and simultaneously to form effective support.

[0009] Preferably, the maximum overhang radius of the folding groove and the chute is equal, and the minimum overhang radius of the folding groove and the chute is equal. The cross-section of the channel is a perfect circle, so the equal maximum overhang radius ensures stable support in all directions. The equal minimum overhang radius is intended to further optimize the initial expansion process of the inner and outer shells, allowing the outer shell to better envelop the inner shell.

[0010] Preferably, the sliding rod includes two groups of connecting rods and connecting shafts, and each connecting shaft passes through a slot to connect two connecting rods.

[0011] The principles of the present invention are as follows:

[0012] A prefabricated box girder prestressed duct drilling device consists of an outermost high-strength rubber pipe and multiple support units. The high-strength rubber pipe can be arranged within the prefabricated box girder's steel skeleton according to the steel bundle alignment. The support units can be combined according to the length of the prestressed duct. Each support unit includes a rotation device for transmitting torque and an opening and closing device for supporting. The support device has two states during use: expanded and contracted. The expanded state is the supporting state, while the contracted state is used for inserting and exiting the prestressed duct.

[0013] The expansion state is achieved as follows: after the support device in the contracted state is inserted into the prestressed channel, the support units at both ends extend out of the prestressed channel, the universal joint of the support unit at one end (hereinafter referred to as the fixed end) is fixed, and the universal joint of the support unit at the other end (hereinafter referred to as the rotating end) is rotated at a constant speed. The support unit in the middle part cannot consume the torque and transmits it to the fixed end; since the universal joint at the fixed end cannot rotate, the threaded part of the main shaft will be affected by the torque and spiral toward the inside of the channel close to the sleeve shaft A, and then the sleeve shaft B and the right universal joint drive the right umbrella joint toward the sleeve shaft A. During movement, the slide rod connected to the zigzag slot drives the inner shell along the slot. During expansion, the inner shell first moves slowly radially outward along the horizontal slot, then rapidly along the zigzag slot. The slide rod connected to the inclined slot drives the outer shell along the slot. During expansion, the outer shell moves radially outward at a uniform speed. Therefore, the outer shell moves at a nearly uniform speed during expansion, while the inner shell moves slowly at first and then rapidly. This prevents interference between the inner and outer shells during expansion and allows both to reach the other end of the slot simultaneously for full expansion. After the slide rod moves from one end of the slot to the other, the support unit at the fixed end has completed expansion. After expansion, the support unit to which it is connected becomes the new fixed end. Continuing to rotate the support unit at the rotating end will cause the new fixed end to expand. Similarly, once the support unit at the rotating end has expanded, the support device is fully expanded. The principle of the contraction state is the same as the expansion state. By reversing the rotating end, the support unit at the fixed end is contracted first, and then the support unit at the rotating end is contracted last.

[0014] The beneficial effects of the present invention are as follows:

[0015] This provides radial support for the high-strength rubber pipe during prestressed channel formation, minimizing overall deformation during hole formation. This prevents blockage of the prestressed channel caused by deformation, water seepage due to cracking, and corrosion of the internal steel bundles. The internal support device is unaffected by ambient temperature fluctuations, ensuring stable support. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural diagram of an embodiment;

[0017] Figure 2 is a schematic structural diagram of the embodiment in a contracted state;

[0018] Figure 3 is a schematic structural diagram of the embodiment in an expanded state;

[0019] Figure 4 It is a structural diagram of the umbrella section;

[0020] Figure 5 is a schematic cross-sectional view of the embodiment in a contracted state;

[0021] Figure 6is a schematic cross-sectional view of the embodiment in an expanded state;

[0022] In the figure, 1 is a supporting unit, 2 is a rotating device, 21 is a main shaft, 22 is a secondary shaft, 23 is a sleeve shaft A, 24 is a sleeve shaft B, 25 is a universal joint, 26 is an umbrella joint, 27 is a slot, 271 is a broken line slot, 272 is an inclined slot, 3 is an opening and closing device, 31 is a sliding rod, 311 is a connecting rod, 312 is a connecting shaft, 32 is an inner shell, 33 is an outer shell, and 4 is a high-strength rubber pipe. DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to the accompanying drawings.

[0024] like Figure 1 As shown, the present invention provides a prefabricated box girder prestressed channel drilling device, applied to one channel of a prefabricated box girder with a span of 26m. The device consists of a high-strength rubber pipe and 150 support units 1. The length of a support unit 1 when fully contracted is 25cm, and the length of a support unit 1 when fully expanded is 20cm. Because the multiple support units 1 are staggered when connected, the combined length of the connected support units 1 is slightly shorter than the sum of the lengths of the individual support units 1, resulting in a connected device length of 30m. Each support unit 1 includes an internal rotating mechanism 2 and an external opening and closing mechanism 3. The rotating mechanism 2 can transmit torque, and the opening and closing mechanism 3 can be contracted and expanded by the rotation of the rotating mechanism 2. The rotating device 2 includes a main shaft 21 and a secondary shaft 22. The left half of the main shaft 21 is provided with a thread, and secondary shafts 22 are provided on the left and right sides of the main shaft 21. The left and right secondary shafts 22 are connected to the main shaft 21 through sleeve shafts A and B. The outer sides of sleeve shafts A and B are fixedly connected to the secondary shaft 22, and the inner side of sleeve shaft A is provided with an internal thread and is spirally connected to the main shaft 21, and the inner side of sleeve shaft B is fixedly connected to the main shaft 21. The secondary shaft 22 is connected in series with a universal joint 25 and an umbrella section 26 along the axial direction from the outside to the inside. The universal joints 25 and umbrella sections 26 at both ends are symmetrical to each other, and the universal joint 25 is fixedly connected to the main shaft 21; the umbrella section 26 is close to the sleeve shaft A or the sleeve shaft B and can rotate around the axis independently. The umbrella section 26 is in the shape of a cross and has four protruding parts. The protruding parts are provided with slots 27, and the protruding radius gradually decreases from the outside to the inside along the axial direction; the slots 27 at the protruding parts have two forms, namely a broken line groove 271 and an oblique groove 272. The broken line groove 271 and the oblique groove 272 are arranged in the same plane of the cross shape and are symmetrical.

[0025] like Figure 2-Figure 4As shown, the opening and closing device 3 includes a slide bar 31 and an inner shell 32 and an outer shell 33 connected to the slide bar. The inner shell 32 and the outer shell 33 are both arc-shaped. The outer shell 33 wraps around the inner shell 32 by flattening the axial edge. The inner shell 32 and the outer shell 33 are respectively connected to the slide bar 31 connected to the folding groove 271 and the inclined groove 272. The purpose of providing two types of slots is to ensure that the opening and closing processes of the inner shell 32 and the outer shell 33 are completed simultaneously without interfering with each other, thereby realizing the stacking of the inner and outer shells. Figure 5 and Figure 6 As shown, the axial edge of the outer shell 33 of the device in the collapsed state overlaps the axial edge of the inner shell, and the two envelop the rotating device 2 to reduce the inner diameter of the device. In this embodiment, the diameter in the collapsed state is 5.5 cm, and the diameter in the expanded state is 7 cm.

[0026] The method of using this embodiment is as follows:

[0027] When casting prefabricated box girders, it is necessary to pre-tie the steel frame. After the frame is tied, the high-strength rubber pipe 4 is erected at the predetermined position of the frame according to the designed line shape. Then the support unit 1 in the contracted state is combined and inserted into the high-strength rubber pipe 4 and led out. The support units 1 at both ends extend out of the pipe, and a specific device is used to fix the universal joint 25 of the support unit 1 at one end, and the universal joint 25 of the support unit 1 at the other end is rotated. The support unit 1 in the middle part cannot consume the torque and transmits it to the fixed end; because the universal joint 25 at the fixed end cannot rotate, the threaded part of the main shaft 21 of the fixed end support unit 1 will be affected by the torque and spiral toward the inside of the channel close to the sleeve shaft A23, and then the sleeve shaft B24 drives the umbrella node to move toward the sleeve shaft A23, and the slide rod 31 connected in the inclined groove 272 drives the outer shell 33 to move along the groove, and the slide rod 31 connected in the broken line groove 271 drives the inner shell 32 to move along the groove. After the slide bar 31 moves from one end of the slot 27 to the other, the support unit 1 at the fixed end expands first. After expansion, the support unit 1 connected to it becomes the new fixed end. Continuing to rotate the support unit 1 at the rotating end expands the new fixed end. Similarly, once the support unit 1 at the rotating end expands, all support units expand. The precast box girder is then poured in an orderly manner. Once the concrete reaches a certain strength, the operation is completed by reversing the support unit 1 at one end and removing the device.

[0028] This embodiment provides radial support for the bellows wall, reducing deformation of the bellows during the formation of prestressed channel holes in prefabricated box girders. This prevents blockage of the prestressed channel caused by bellows deformation, prevents water seepage caused by cracking of the bellows, and avoids corrosion of the steel strands caused by internal moisture. The support unit in this embodiment is unaffected by temperature fluctuations and provides effective and stable support.

[0029] The contents described in the embodiments of this specification are merely an enumeration of the implementation forms of the inventive concept. The scope of protection of the present invention should not be regarded as limited to the specific forms described in the embodiments. The scope of protection of the present invention also extends to equivalent technical means that can be conceived by those skilled in the art based on the inventive concept.

Claims

1. A prefabricated box girder prestressed channel drilling device, comprising an outermost high-strength rubber pipe (4), characterized in that: A plurality of interconnected support units (1) are provided inside the high-strength rubber pipe (4); The support unit (1) further includes an internal rotating device (2) and an external opening and closing device (3); The rotating device (2) includes a main shaft (21) and auxiliary shafts (22) arranged on the left and right sides of the main shaft (21), a sleeve shaft A (23) is fixed to the right end of the left auxiliary shaft (22), a thread is provided on the left half of the main shaft (21), and the sleeve shaft A (23) is spirally connected to the main shaft (21); a sleeve shaft B (24) is fixed to the left end of the right auxiliary shaft (22), and the sleeve shaft B (24) is fixedly connected to the main shaft (21); the auxiliary shaft (22) is also connected in series with a fixed universal joint (25) and a cross-shaped umbrella section (26) along the axial direction from the outside to the inside, and the extension radius of the umbrella section (26) gradually decreases along the axial direction from the outside to the inside; a slot hole (27) is provided at the extension of the umbrella section (26), and the slot hole (27) includes an inclined slot (272) and a broken line slot (271), and the inclined slot (272) or the broken line slot (271) is symmetrically arranged in the plane of the umbrella section (26); The opening and closing device (3) comprises a plurality of slide bars (31), an inner shell (32) and an outer shell (33); the slide bars (31) are slidably connected to the slot (27); the inner shell (32) is fixed on the slide bars (31) connected to the folding groove (271); the outer shell (33) is fixed on the slide bars (31) connected to the inclined groove (272); the outer shell (33) is overlapped with the inner shell (32) by enveloping the flattened axial edge; the bending angle of the folding groove (271) along the axial direction is smaller than the inclination angle of the inclined groove (272) along the axial direction.

2. The prefabricated box beam prestressed duct drilling device according to claim 1, characterized in that: The maximum extension radius of the folding groove (271) is equal to that of the inclined groove (272), and the minimum extension radius of the folding groove (271) is equal to that of the inclined groove (272).

3. The prefabricated box beam prestressed duct drilling device according to claim 1, characterized in that: The sliding rod (31) includes two groups of connecting rods (311) and a connecting shaft (312), and each connecting shaft (312) passes through a slot (27) to connect two connecting rods (311).

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