Box girder internal mold dismantling device

Abstract

The invention relates to the technical field of bridge engineering construction, and discloses a box girder internal mold dismantling device which comprises a bearing cross beam system, a supporting cross beam system, a supporting cross beam system and a supporting cross beam system, the upper end of the screw jacking system is vertically arranged on the bearing cross beam system, the lower end of the screw jacking system is provided with a pressure bearing part, and the pressure bearing part abuts against the inner top face of the box girder inner mold; and the flexible buffer layer is arranged on the outer surface of the box girder inner mold and is used for isolating the box girder inner mold from the inner wall of the box girder concrete during mold removal. According to the box girder internal formwork dismantling device, the technical problem that in box girder prefabricating construction, when an internal formwork is dismantled, the inner wall of box girder concrete is prone to being scratched, collided and the like can be solved.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering construction technology, specifically to a box girder inner formwork removal device. Background Technology

[0002] During the construction of precast box girders for highway and railway bridges, the inner formwork (i.e., the inner mold) needs to be removed after the concrete has been poured and reached a certain strength. Currently, the inner mold is mostly removed by pulling it out as a whole or by removing it in sections. Due to the strong adhesion and friction between the inner mold and the concrete, and the difficulty in achieving absolutely synchronous and uniform separation during the removal process, the edges and corners of the inner mold are very likely to bump or scratch the concrete surface inside the box girder.

[0003] This type of damage typically manifests as scratches, chipped corners, or even exposed rebar on the concrete surface. This not only affects the aesthetics of the structure, but more seriously, the damaged concrete layer reduces its ability to protect the reinforcing steel, impacting the structure's durability. Current technologies often employ applying release agents to the inner mold surface to reduce adhesion, but the effect is limited and cannot completely prevent mechanical damage. For existing damage, additional repairs are required, which is time-consuming, labor-intensive, increases construction costs, and affects construction efficiency. Summary of the Invention

[0004] This invention was made to solve the above-mentioned technical problems, and its purpose is to provide a box girder inner formwork removal device to solve the problem that existing formwork removal methods easily lead to damage to the inner wall of the box girder concrete.

[0005] According to one embodiment of the present invention, a box girder inner formwork removal device is provided, comprising: a supporting beam system that spans across and is disposed above the top plate of the box girder; The screw lifting system is vertically mounted on the supporting beam system at its upper end and has a pressure-bearing part at its lower end, which abuts against the inner top surface of the box girder inner formwork. A flexible buffer layer is provided on the outer surface of the inner formwork of the box girder to isolate the inner formwork of the box girder from the inner wall of the box girder concrete during demolding.

[0006] In one embodiment, the screw lifting system includes: a lifting screw, an adjusting handwheel, and a pressure plate; The upper end of the lifting screw is threadedly connected to the supporting beam system, and the lower end is fixedly connected to the pressure bearing pad. The adjusting handwheel drives the lifting screw to rotate and generate axial displacement relative to the supporting beam system.

[0007] As one embodiment, the outer surface of the lifting screw is provided with axial scale lines.

[0008] As one implementation, the supporting beam system includes: at least two beam units and connectors; The connector is disposed between the beam units and is used to connect the beam units.

[0009] In one embodiment, the beam unit is an I-beam or a channel steel.

[0010] As one embodiment, a connecting plate is provided at the end of the beam unit, and a through hole is provided on the connecting plate; The connector is inserted into the through hole.

[0011] In one embodiment, the flexible buffer layer is a polymer sheet or an elastic rubber sheet; The thickness of the flexible buffer layer is 3mm to 10mm.

[0012] As one implementation, the edge of the flexible buffer layer is provided with a covering edge that bends towards the corner of the inner mold of the box girder. The covering edge is used to cover and protect the corner and increase the contact area with the concrete.

[0013] In one embodiment, the limiting mechanism is disposed between the supporting beam system and the top plate of the box girder to restrict the horizontal movement of the supporting beam system.

[0014] In one implementation, the number of screw lifting systems is at least two; Each of the screw lifting systems is arranged at intervals along the length of the supporting beam system.

[0015] Based on the above description and practice, it can be seen that the box girder inner formwork removal device of the present invention, before demolding, provides a uniform and controllable downward pushing force by rotating the screw of the adjustable jacking system, enabling the entire inner formwork to overcome the adhesion force between itself and the concrete and smoothly separate from the concrete surface. During this process, pre-laid flexible pads act as a buffer layer, effectively preventing direct hard scraping between the metal formwork and the concrete surface. After the inner formwork is separated from the concrete, it can be safely lifted out using equipment such as a gantry crane. This invention patent completely avoids damage to the concrete during demolding from two aspects: "active jacking" and "passive protection," ensuring the smooth and intact inner wall of the concrete after demolding, eliminating the need for subsequent repairs, and improving construction efficiency and project quality. Attached Figure Description

[0016] Figure 1 and Figure 2 This is a structural schematic diagram of the box girder inner formwork removal device from different perspectives in one embodiment of the present invention.

[0017] The attached figures are labeled as follows: 101. Box girder top plate; 102. Box girder web plate; 201. Supporting crossbeam system; 202. Box girder inner formwork; 203. Screw lifting system. Detailed Implementation

[0018] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0019] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. It should be noted that in this disclosure, the terms "comprising," "configured with," and "set in" are used to indicate an open-ended inclusion, meaning that additional elements / components / etc. may exist besides those listed; the terms "first," "second," etc., are used only as labels and are not intended to limit the number or order of objects; the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0020] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] According to one embodiment of the present invention, a box girder inner formwork removal device is provided, which is described below in conjunction with... Figure 1 and Figure 2 The device for removing the inner formwork of the box girder is described below.

[0022] The box girder inner formwork removal device includes a supporting beam system, a screw lifting system, and a flexible buffer layer. First, after the box girder reinforcement is tied, the inner formwork 202 is hoisted into place, and its internal supports are fixed, the flexible buffer layer is laid. Then, the box girder concrete is poured and cured. Once the concrete strength reaches the design requirement for demolding, the supporting beam system and the screw lifting system are installed and lifted. Specifically, the supporting beam system 201 typically consists of two sturdy metal beams, which are strung across the top of the box girder, with both ends firmly supported on the concrete top slabs 101 on both sides of the box girder. The screw lifting system 203 is vertically installed, with its upper end connected to the middle of the supporting beam via threads, and its lower bearing portion accurately placed at the center of the inner top surface of the inner formwork 202. The flexible buffer layer is a peelable pad that is inserted or attached to the contact interface between the inner formwork and the inner wall of the box girder concrete before removal. When demolding is required, the pressure-bearing part applies downward force through the drive screw lifting system 203. This force is transmitted through the inner mold body, enabling the entire inner mold to overcome the adhesion and friction between itself and the concrete, achieving uniform and integral vertical separation, rather than the traditional tilting and pulling. During this process, the flexible buffer layer effectively isolates the rigid formwork from direct contact with the concrete surface, thus ensuring the smooth and undamaged inner wall of the concrete.

[0023] In a preferred embodiment of the present invention, the screw lifting system 203 includes a lifting screw, an adjusting handwheel, and a pressure-bearing plate. The upper end of the lifting screw is threadedly connected to the supporting beam system, and the lower end is fixedly connected to the pressure-bearing plate. The adjusting handwheel drives the lifting screw to rotate and generate axial displacement. Specifically, the upper end of the screw is machined with external threads, which engage with a sleeve or nut seat with matching internal threads fixed in the middle of the supporting beam 201. The lower end of the screw is fixed with a pressure-bearing plate by welding or bolting, etc. The pressure-bearing plate constitutes the pressure-bearing part that is in direct contact with the inner mold. The pressure-bearing plate is usually a square or round steel plate with an area larger than the end of the screw, used to distribute pressure and avoid excessive pressure damaging the inner mold. An adjusting handwheel is installed on the top of the screw. By rotating the handwheel clockwise or counterclockwise, the operator can drive the lifting screw to move axially upward or downward under the action of the threaded pair.

[0024] Furthermore, clear graduation lines are laser-etched or pasted along the axial direction on the smooth section of the lifting screw. These graduation lines can be used in conjunction with a fixed pointer mounted on the supporting beam. The pointer, positioned on a nut seat and aligned with a fixed reference line on the screw, allows for estimation of displacement by rotating the screw a certain number of times. During operation, by observing the changes in the graduations indicated by the pointer, the extension length of the screw or the downward displacement of the inner mold can be read in real time and intuitively, ensuring that multiple lifting points descend synchronously and equally. This is crucial for achieving smooth and uniform disengagement of the inner mold. For example, all lifting points can be set to rotate the handwheel the same number of times each time, or controlled to descend to the same graduation value.

[0025] The supporting beam system 201 is not a single long beam, but rather assembled on-site from at least two standard-length beam units connected by connectors. When the width of the box girder top plate 101 is large, multiple beam units can be connected in series; when the width is small, the number of units can be reduced or shorter units can be used. The assembled supporting beam system 201 greatly enhances the applicability of the device and facilitates transportation and storage. The beam units are preferably made of widely used structural steel with excellent mechanical properties, such as I-beams or channel steel. I-beams, due to their large moment of inertia, deform less under the same bending moment, thus more effectively ensuring the transmission efficiency of the lifting force and the stability of the entire device. Channel steel, on the other hand, is easier to process into connectors. At the end of each beam unit, a connecting plate is fixedly installed. This connecting plate has a certain number of through holes of uniform diameter pre-drilled. When two beam units need to be connected, the operator simply aligns their ends, inserting the connecting plates into these aligned through holes and tightening with nuts and washers. High-strength bolts are preferred as the connecting components. The bolted connection is simple in structure, reliable in force transmission, and quick to assemble and disassemble, meeting the needs of rapid assembly and adjustment on construction sites and ensuring the overall rigidity and load-bearing capacity of the supporting beam system 201.

[0026] The flexible buffer layer serves to provide cushioning and isolation during demolding. The material selected for the buffer layer must possess good flexibility, wear resistance, a certain tear strength, and low surface adhesion. In practical engineering, commonly used polymer sheets, such as ultra-high molecular weight polyethylene (UHMWPE) sheets, have an extremely low coefficient of friction and self-lubricating properties, significantly reducing frictional resistance during separation. Another commonly used material is oil-resistant and aging-resistant engineering rubber sheets, which offer even better elastic cushioning. The thickness of the flexible buffer layer is preferably controlled between 3 mm and 10 mm. This range provides effective cushioning and isolation without compromising the accuracy of the internal clearance dimensions of the box girder or causing excessive compressive deformation leading to uneven stress distribution. During construction, buffer sheets with a pressure-sensitive adhesive layer on one side are selected and precisely cut according to the shape and dimensions of each part of the box girder inner mold 202 to ensure complete coverage without omissions and as tight a joint as possible. Then, before the box girder concrete is poured, it is laid on the outer surface of the inner formwork of the box girder. Its adhesion to the concrete is much less than the adsorption force between the formwork and the concrete. During the lifting and demolding process, it can be peeled off along with the formwork and plays a buffering role in the peeling process. To further enhance the protection of weak points, the edge of the flexible buffer layer can be specially treated to form a continuous and extending wrapping edge. Specifically, the edge width is reserved during cutting, or a flanged structure is molded during factory prefabrication. During pasting, not only is the main body of the plate flat, but this wrapping edge is also deliberately bent at a 90-degree or larger angle to tightly wrap all the outer edges of the inner formwork 202 of the box girder. The edges of the inner formwork of the box girder are the parts with the most stress concentration and the most vulnerable to damage to the concrete. This wrapping edge design is equivalent to adding a protective sleeve to all sharp edges and corners, achieving all-round protection from surface to edge, and completely eliminating damage to the concrete from rigid edges and corners.

[0027] During the jacking operation, the downward jacking force generated by the screw jacking system 203 is ultimately transmitted to the top plate 101 of the box girder through the supporting beam system 201. To ensure the stability of the entire device under stress and to prevent slippage of the supporting beam system 201 due to small horizontal components, operational vibrations, or accidental collisions, the device is equipped with a limiting mechanism. The limiting mechanism is used to provide lateral restraint, rather than bearing vertical loads. One embodiment involves welding or bolting a vertical limiting baffle to the bottom of both ends of each beam that makes up the supporting beam system 201, near the inner side of its contact point with the top plate 101 of the box girder. During installation, the limiting baffle is placed tightly against the inner surface of the web 102 of the box girder or the vertical surface of the edge of the top plate of the box girder. When the beam tends to move laterally, the limiting baffle will abut against the solid concrete structure, thereby restricting its movement. Another implementation involves pre-setting several sets of short steel bar ends as positioning piles on the top slab 101 during the pouring of the box girder concrete. When installing the supporting beam system 201, its ends are inserted into the area defined by these positioning piles. The limiting mechanism has a simple structure and low cost, which can significantly improve the safety and controllability of the entire jacking operation, ensuring that the direction of the jacking force is always along the predetermined vertical direction, and avoiding accidental risks caused by equipment slippage or lateral compression of the concrete structure.

[0028] The number of screw jacking systems 203 is set to at least two, and they are arranged at intervals along the length of the supporting beam system 201 according to the length of the inner formwork 202 of the box girder. For example, for a standard box girder with a length of 30 meters, three screw jacking systems 203 can be evenly set on the supporting beam system 201, corresponding to approximately one-third of the length of the inner formwork. All jacking points are connected into an integral load-bearing frame by the rigid supporting beam system 201. During the formwork dismantling operation, operators need to be in position at each jacking point and work together. Since the operating torque of the adjusting handwheels at each jacking point is similar, and displacement can be calibrated by the scale lines, high-precision synchronous pressing can be achieved, ensuring that all points along the entire length of the inner formwork 202 of the box girder separate from the concrete almost simultaneously and equally, eliminating shear stress or bending stress caused by asynchronous operation.

[0029] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A box girder inner formwork removal device, characterized in that, include: The supporting beam system spans across and is positioned above the top slab of the box girder; The screw lifting system is vertically mounted on the supporting beam system at its upper end and has a pressure-bearing part at its lower end, which abuts against the inner top surface of the box girder inner formwork. A flexible buffer layer is provided on the outer surface of the inner formwork of the box girder to isolate the inner formwork of the box girder from the inner wall of the box girder concrete during demolding.

2. The box girder inner formwork removal device as described in claim 1, characterized in that, The screw lifting system includes: a lifting screw, an adjusting handwheel, and a pressure plate; The upper end of the lifting screw is threadedly connected to the supporting beam system, and the lower end is fixedly connected to the pressure bearing pad. The adjusting handwheel drives the lifting screw to rotate and generate axial displacement relative to the supporting beam system.

3. The box girder inner formwork removal device as described in claim 2, characterized in that, The outer surface of the lifting screw is provided with axial graduation lines.

4. The box girder inner formwork removal device as described in claim 1, characterized in that, The supporting beam system includes: at least two beam units and connectors; The connector is disposed between the beam units and is used to connect the beam units.

5. The box girder inner formwork removal device as described in claim 4, characterized in that, The beam unit is an I-beam or a channel steel.

6. The box girder inner formwork removal device as described in claim 4, characterized in that, A connecting plate is provided at the end of the beam unit, and a through hole is provided on the connecting plate; The connector is inserted into the through hole.

7. The box girder inner formwork removal device as described in claim 1, characterized in that, The flexible buffer layer is a polymer plate or an elastic rubber plate; The thickness of the flexible buffer layer is 3mm to 10mm.

8. The box girder inner formwork removal device as described in claim 1, characterized in that, The edge of the flexible buffer layer is provided with a covering edge that bends towards the inner corner of the box girder. The covering edge is used to cover and protect the corner and increase the contact area with the concrete.

9. The box girder inner formwork removal device as described in claim 1, characterized in that, Also includes: Limiting mechanism; The limiting mechanism is located between the supporting beam system and the top plate of the box girder to restrict the horizontal movement of the supporting beam system.

10. The box girder inner formwork removal device as described in claim 1, characterized in that, The number of screw lifting systems is at least two; Each of the screw lifting systems is arranged at intervals along the length of the supporting beam system.

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