Novel length-adjustable steel pipe system device

Abstract

The invention relates to the technical field of constructional engineering, in particular to a novel length-adjustable steel pipe system device which comprises an outer sleeve, an inner steel pipe, positioning screw holes and a bolt assembly, the outer sleeve and the inner steel pipe are made of the same material, the wall thickness is 3.0 mm, the length of the outer sleeve is 1.2 m or 1.5 m, the outer diameter is larger than 51 mm, the positioning screw holes are formed in the axial direction of the outer sleeve every 300 mm, and the bolt assembly is connected with the inner steel pipe. The inner steel pipe can penetrate through the outer sleeve in a sliding mode, and the inner steel pipe and the outer sleeve can be locked and fixed through a bolt assembly after hole positions are accurately aligned. By adjusting the extension length of the inner steel pipe and fixing the inner steel pipe, adaptation of different heights is achieved, cutting of the steel pipe, adaptation of a formwork supporting frame, a pitched roof scaffold and other scenes are not needed, the device is easy and convenient to operate, rapid to install and capable of being repeatedly used, material loss and labor cost are greatly reduced, construction efficiency and safety are improved, and the device has remarkable practical value.

Description

Technical Field

[0001] This invention relates to the field of building engineering technology, specifically to a novel adjustable-length steel pipe system device. Background Technology

[0002] In construction engineering, scaffolding is a core facility for ensuring work safety and supporting the construction structure. Scaffolding steel pipes, as the core material for erecting scaffolding, are used in various construction scenarios, including formwork support frames, scaffolding for sloping roofs, and underground parking garage support. Commonly known scaffolding steel pipes are mostly made of tubular steel, with standard specifications of an outer diameter of 48mm and a wall thickness of 3.0mm. Depending on their installation position and function within the scaffolding, they can be divided into key components such as uprights, horizontal bars, and ground-level bars, which together form a stable support system and are an indispensable basic material in construction.

[0003] However, the requirements for scaffolding steel pipe lengths vary significantly and require considerable flexibility in construction scenarios. For example, during the erection of formwork support frames, situations often arise where the free end height of the uprights exceeds the standard, causing the support to fail to meet safety specifications. During construction on pitched roofs, due to the irregular slope, scaffolding uprights at different locations need to be adapted to varying heights to ensure the flatness and stability of the support. Furthermore, construction in special areas such as underground parking garages and low-ceilinged indoor spaces also requires targeted adjustments to steel pipe lengths to meet space constraints. These scenarios all impose strict requirements on the adaptability of scaffolding steel pipe lengths, necessitating flexible adjustments to the pipe lengths based on actual construction needs to ensure both construction quality and safety.

[0004] Currently, the industry's common solution for meeting the demand for steel pipes of different lengths is on-site cutting. The specific process is as follows: before construction, the length is calculated based on the target height to determine the specific dimensions of the required steel pipes. Then, standard-length steel pipes are cut on-site using cutting machinery, and the cut pipes are then used for scaffolding erection. For example, in the construction of formwork support frames for pitched roofs, the appropriate length of each upright must be accurately calculated first to avoid dimensional deviations after cutting that render the pipes unusable. Then, personnel are organized to cut and install them. When the height of the free end of the formwork support frame does not meet the specifications, the conventional approach is to add an extra step to the frame, extending the overall height to meet safety standards.

[0005] However, existing technical solutions have several prominent problems: First, there is serious material waste. On-site cutting generates a large amount of steel pipe waste, and the short pipes after cutting are of fixed length, making it difficult to adapt to the needs of other construction scenarios, resulting in low material utilization. Furthermore, the practice of adding extra scaffolding further increases the unnecessary consumption of scaffolding materials. Second, the construction process is cumbersome. Precise dimensional calculations are required before cutting, and the cutting process requires operating cutting machinery and coordinating multiple operators, which not only prolongs the construction cycle but also increases labor coordination costs. Third, there is a lack of flexibility. The fixed length of the cut steel pipes cannot be adjusted according to temporary changes in height requirements during construction. If there is an error in dimensional calculation, the cut steel pipes will be scrapped, further affecting construction efficiency. Fourth, on-site cutting operations pose certain safety hazards. Operating cutting machinery requires specialized skills, and the waste and noise generated during the cutting process can potentially impact the construction environment and the safety of operators.

[0006] The shortcomings of the existing technologies have resulted in the long-standing inability to effectively solve the problem of matching the length of scaffolding steel pipes in construction. This has increased construction costs, reduced construction efficiency, and posed safety risks, becoming a significant factor restricting the advancement of refined and efficient construction. Summary of the Invention

[0007] The purpose of this invention is to provide a novel adjustable-length steel pipe system device to solve the problems mentioned in the background art, such as the waste of materials and cumbersome construction caused by the need for on-site cutting of traditional steel pipes to adapt to the required length.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A novel adjustable-length steel pipe system includes an outer sleeve, an inner steel pipe, positioning screw holes, and bolt assemblies. The inner steel pipe can slide axially through the interior of the outer sleeve, forming a telescopic fit structure. The positioning screw holes are respectively opened through the side wall of the outer sleeve and the side wall of the inner steel pipe, and the positioning screw holes on the outer sleeve and the inner steel pipe can be aligned at different relative positions. The bolt assembly includes mutually compatible bolts and matching nuts. The bolt assembly is detachably inserted into aligned positioning bolt holes. The relative fixation of the outer sleeve and inner steel tube is achieved through the locking engagement of the bolts and matching nuts. The total length of the device is precisely adjusted using the formula L = L1 + L2, where L is the total length of the device, L1 is the effective working length of the outer sleeve, and L2 is the length of the inner steel tube extending beyond the outer sleeve, and L2 ∈ [0, L1 + L2]. 2max ], L 2max The maximum protruding length of the inner steel pipe is determined by the difference between the length of the outer sleeve and the length of the inner steel pipe. By adjusting the sliding stroke of the inner steel pipe within the outer sleeve, the positioning screw holes of both are aligned at the target position and fixed by the bolt assembly, thereby achieving length adjustment of the entire steel pipe system device, adapting to different height requirements in building construction, such as formwork support frames and scaffolding on sloping roofs.

[0009] Preferably, the outer sleeve and the inner steel pipe are made of the same high-strength steel material, and both have a wall thickness of 3.0 mm. The axial bearing capacity of the device satisfies the formula F=σ. s ·A, where σ s Let A be the yield strength of the high-strength steel, and A be the effective stress-bearing area of ​​the device's cross-section. D is the outer diameter of the outer sleeve or the outer diameter of the inner steel pipe, and t=3.0mm is the wall thickness, ensuring that the device is subjected to uniform stress and meets the load-bearing and deformation resistance requirements in building construction. The outer diameter of the outer sleeve is set to 51mm to 60mm, and the gap between the inner diameter of the outer sleeve and the outer diameter of the inner steel pipe satisfies the formula δ=D1-D2, where δ is the fitting gap, D1 is the inner diameter of the outer sleeve, D2 is the outer diameter of the inner steel pipe, and δ∈[0.5mm,1mm]. This gap ensures that the inner steel pipe slides smoothly in the outer sleeve and avoids excessive shaking during the adjustment process.

[0010] Preferably, the outer sleeve has two lengths: 1.2m or 1.5m, and the inner steel pipe has a length of 0.8m to 3.0m. By combining the two specifications of outer sleeve with inner steel pipes of different lengths, the length can be adjusted within the range of 0.8m to 4.5m, covering most of the scaffolding height requirements in building construction.

[0011] Preferably, the positioning screw holes on the outer sleeve are evenly distributed along its axial direction, the center distance between two adjacent positioning screw holes is 300mm, and the number of positioning screw holes is not less than 4; the positioning screw holes on the inner steel pipe are provided in 2 to 4 sets, each set including 2 positioning screw holes symmetrically opened on both sides of the inner steel pipe, to ensure the stability of the connection between the outer sleeve and the inner steel pipe.

[0012] Preferably, the bolts in the bolt assembly are high-strength bolts of M12 to M16 specifications. The bolt thread length is 8mm to 12mm longer than the sum of the wall thickness of the outer sleeve and the inner steel pipe. The matching nut is a nylon lock nut, and a flat washer and a spring washer are also provided between the nut and the outer wall of the outer sleeve to further improve the anti-loosening performance and seismic resistance of the connection structure.

[0013] Preferably, both ends of the outer sleeve are provided with rounded corner transition structures with a rounded corner radius of 2mm to 3mm; the insertion end of the inner steel tube is provided with a guide chamfer with a chamfer angle of 30° to 45° and a chamfer length of 5mm to 8mm, which facilitates the quick insertion of the inner steel tube into the outer sleeve and avoids sharp ends from scratching operators or construction materials.

[0014] Preferably, the inner sleeve has an integrally formed annular limiting protrusion near one end of its interior, and the outer peripheral wall of the inner steel tube at the end away from the insertion end is provided with annular limiting steps that are adapted to the annular limiting protrusion. When the inner steel tube slides outward to the limit position, the annular limiting steps abut against the annular limiting protrusion to form a mechanical limit, preventing the inner steel tube from completely coming out of the outer sleeve.

[0015] Preferably, the outer surfaces of the outer sleeve and the inner steel pipe are both treated with hot-dip galvanizing for corrosion protection, with a galvanizing layer thickness of 85μm to 120μm. The inner walls of the positioning screw holes are processed by tapping after galvanizing, and after tapping, they are also treated with anti-rust oil immersion, which significantly improves the weather resistance and corrosion resistance of the device and extends its service life in outdoor construction environments.

[0016] Preferably, the outer wall of the outer sleeve is marked with spacing and serial number markings corresponding to the position of each positioning screw hole. The spacing markings indicate the center-to-center distance between adjacent positioning screw holes as "300mm", and the serial number markings are sequentially marked as "1, 2, 3..." starting from one end of the outer sleeve. The outer wall of the inner steel pipe is marked with group number markings corresponding to the position of each group of positioning screw holes as "1-1, 1-2...". Operators can quickly determine the extension length of the inner steel pipe by matching the serial number markings on the outer sleeve with the group number markings on the inner steel pipe, achieving precise alignment of the positioning screw holes without additional measurement, and further improving construction adjustment efficiency.

[0017] As a preferred option, the operation process includes the following steps: Step 1: Construction preparation. Based on the target height requirement H of the formwork support frame or scaffolding on the sloping roof in the construction, select the corresponding specifications of outer sleeve, inner steel pipe and bolt assembly according to the formula L=H. Check that the positioning screw holes on the outer sleeve and inner steel pipe are not blocked by debris and that the bolts and matching nuts of the bolt assembly are properly matched. Step 2: Preliminary assembly. Slowly insert the inner steel tube with the guide chamfered end into the outer sleeve along its axial direction. Adjust the extension length L2 of the inner steel tube within the outer sleeve according to the target height, ensuring L2 < L. 2max Furthermore, the inner steel pipe did not exceed the limit range of the annular limit protrusion; Step 3: Hole alignment. Position the holes by matching the serial number markings on the outer sleeve with the group number markings on the inner steel tube, or by directly observing the hole positions and fine-tuning the axial position of the inner steel tube to ensure that any one of the positioning screw holes on the outer sleeve is precisely coaxially aligned with a group of positioning screw holes on the inner steel tube. Step 4: Tighten and fix. Insert the bolts in the bolt assembly into the aligned positioning screw holes from one side of the outer sleeve. Then, put flat washers and spring washers on the other end of the bolts in sequence. Finally, tighten the matching nuts until the bolt assembly is tightly fitted to the outer wall of the outer sleeve and the inner steel pipe to achieve a stable connection between the three. Step 5: Verification and acceptance. Use measuring tools to verify whether the overall length L of the device meets the requirement of |LH|≤5mm. At the same time, check the tightness of the bolt assembly to ensure that there is no looseness. After the acceptance is qualified, the device can be installed on the top of the scaffold upright to complete the adjustment and fixation of the scaffold height.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention fundamentally solves the material waste problem caused by traditional steel pipe cutting processes. Traditional construction requires on-site cutting of steel pipes according to different height requirements, generating a large amount of waste and making it difficult to reuse the cut short pipes, resulting in idle resources. This device, however, uses a telescopic design between the outer sleeve and the inner steel pipe, eliminating the need for any cutting of the steel pipe. Different lengths can be achieved by adjusting the relative positions of the two components, completely eliminating material loss from cutting. Furthermore, all components of the device are reusable. Whether for conventional formwork support frames, scaffolding on pitched roofs, or low-ceilinged support scenarios, height adjustment can be achieved using the same device, significantly improving the utilization rate of steel pipe materials and reducing resource waste.

[0019] 2. This invention significantly simplifies the construction process, resulting in a substantial improvement in construction efficiency. Traditional methods require multiple cumbersome steps, including length calculation, on-site cutting, and splicing adjustments. Furthermore, the cutting operation necessitates the coordinated efforts of multiple operators, making it time-consuming and labor-intensive. This device, however, utilizes the precise alignment of positioning screw holes and bolt components. Installation and fixation are completed simply by inserting the inner steel pipe into the outer sleeve, adjusting it to the target length, aligning the holes, and tightening the bolts. The entire operation requires no complex machinery and can be completed independently by a single person, eliminating unnecessary steps such as cutting, measurement, and calibration. This effectively shortens the time required for scaffolding erection and adjustment, making it particularly suitable for construction scenarios with varying heights, such as sloping roofs, allowing for highly efficient construction progress.

[0020] 3. The device of this invention boasts exceptional ease of operation and broad adaptability to various scenarios. Its telescopic structural design allows for flexible and efficient length adjustment. Positioning screw holes spaced every 300mm on the outer sleeve, combined with corresponding holes in the inner steel pipe, enable precise adjustment at multiple levels, meeting diverse height requirements from low-ceilinged spaces to high-altitude operations. No professional skills training is required for operation; operators can easily align and fix the holes through intuitive observation, significantly lowering the construction threshold. Whether adjusting the height of the free end of a formwork support frame or adapting to the irregular height of scaffolding on a pitched roof, this device responds quickly to needs without requiring additional auxiliary components, offering far greater adaptability than traditional cutting and splicing methods.

[0021] 4. This invention ensures construction safety while effectively controlling construction costs. Traditional cutting operations involve mechanical risks, and the stability of the spliced ​​steel pipe structure is poor, easily leading to safety hazards. This device uses the same high-strength material as traditional scaffolding steel pipes, with a uniform wall thickness of 3.0mm, and is secured with bolt assemblies, ensuring the structure's load-bearing capacity and stability, reducing safety risks caused by loose splicing. Simultaneously, reduced material waste and increased construction efficiency directly lower material procurement and labor costs, eliminating the need for additional cutting equipment and maintenance costs. Furthermore, its service life can be extended through hot-dip galvanizing for corrosion protection during long-term use, further reducing the overall life-cycle construction cost. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are explained in detail together with the embodiments of the invention, but do not constitute a limitation thereof.

[0023] Figure 1 This is a schematic diagram of the structure before construction and adjustment of the present invention; Figure 2 This is a schematic diagram of the structure after construction and adjustment according to the present invention; Figure 3 This is a schematic flowchart of the operation method of the present invention. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1 (Conventional Template Support Frame Adaptation Example) This embodiment is applicable to the height adjustment of conventional formwork support frames in building construction (target height 2.2m). The core structure and application details are as follows: 1. Core structure and specifications Outer sleeve 1: Made of the same high-strength steel as the scaffolding steel pipe, with a length of 1.2m, an outer diameter of 53mm, a wall thickness of 3.0mm, and an inner diameter of 53-2×3.0=47mm; both ends are equipped with rounded transition structures with a radius of 2.5mm to prevent sharp ends from scratching operators or construction materials; the outer surface is treated with hot-dip galvanizing for corrosion protection, with a zinc layer thickness of 90μm, improving corrosion resistance in outdoor construction environments.

[0026] Inner steel pipe 2: Made of the same material as outer sleeve 1, with a length of 1.8m, an outer diameter of 46.4mm, and a wall thickness of 3.0mm; the insertion end is provided with a guide chamfer with a chamfer angle of 35° and a chamfer length of 6mm, which facilitates quick insertion into the inner sleeve 1; the outer surface is also hot-dip galvanized with a zinc layer thickness of 88μm, forming a unified anti-corrosion system with the outer sleeve 1.

[0027] Fit clearance: The fit clearance between the inner diameter of the outer sleeve 1 and the outer diameter of the inner steel pipe 2 is 47-46.4=0.6mm. This clearance design ensures that the inner steel pipe 2 slides smoothly along the axial direction in the outer sleeve 1 without jamming, and also avoids excessive shaking during adjustment, thus ensuring structural stability.

[0028] 2. Locating screw holes and bolt assembly Positioning screw holes 3: Five positioning screw holes 3 are evenly opened along the axial direction of the outer sleeve 1. The center distance between two adjacent positioning screw holes 3 is 300mm, and the screw hole diameter is 13mm to ensure adjustment accuracy and structural strength. Three sets of positioning screw holes 3 are set on the side wall of the inner steel tube 2. Each set includes two symmetrically opened screw holes with the same screw hole diameter as the outer sleeve 1. The first set of positioning screw holes 3 is 250mm away from the insertion end of the inner steel tube 2, and the spacing between each set is 400mm to meet the fixing requirements of different extension lengths.

[0029] Bolt assembly 4: includes M12 high-strength bolts and matching nylon lock nuts. The bolt thread length is 3.0 + 3.0 + 10 = 16 mm (matching the sum of the wall thicknesses of the outer sleeve 1 and the inner steel pipe 2). When assembling, it is equipped with φ12 flat washers and spring washers. The flat washers are 2 mm thick and the spring washers are 12 mm in diameter, which can effectively improve the anti-loosening performance of the connection structure and prevent loosening due to vibration during construction.

[0030] 3. Adjustment and Operation Process 1) Before construction, based on the target height of 2.2m, the length that the inner steel pipe 2 needs to extend beyond the outer sleeve 1 is determined to be 2.2-1.2=1.0m; 2) Insert the inner steel pipe 2 with the guide chamfered end slowly into the inner sleeve 1 along the axial direction of the outer sleeve 1, and initially adjust it to the approximate protrusion length; 3) Observe the positioning screw holes 3 on the outer sleeve 1 and the inner steel pipe 2, and finely adjust the axial position of the inner steel pipe 2 so that the fourth positioning screw hole 3 on the outer sleeve 1 and the second set of positioning screw holes 3 on the inner steel pipe 2 are precisely coaxially aligned. 4) Insert the bolt in the bolt assembly 4 into the aligned positioning screw hole 3 from one side of the outer sleeve 1, and then put the flat washer and spring washer on the other end of the bolt in sequence. Finally, tighten the matching nylon lock nut until the bolt assembly 4 is tightly fitted with the outer wall of the outer sleeve 1 and the inner steel pipe 2 to achieve a stable connection between the three. 5) Use a measuring tape to verify the total length of the device, and control the error within ±3mm to ensure that it meets the height requirements of the template support frame.

[0031] 4. Application Effects This device eliminates the need for cutting steel pipes, allowing for length adjustment directly through the telescopic cooperation between the outer sleeve 1 and the inner steel pipe 2. Installation and debugging can be completed by a single operator, saving more than 60% of labor costs compared to traditional cutting methods. The even distribution of positioning screw holes 3 ensures precise adjustment, and with the locking and fixing of bolt assembly 4, the device's axial load-bearing capacity can reach 158kN, meeting the load-bearing requirements of conventional formwork support frames, without material waste, and significantly improving construction efficiency.

[0032] Example 2 (Adaptation Example for Sloping Roof Scaffolding) This embodiment is applicable to the height adaptation of scaffolding in sloping roof construction (target height 4.5m). It addresses the irregular height variations of sloping roofs by achieving flexible adjustment and stable support, as detailed below: 1. Core structure and specifications Outer sleeve 1: Made of high-strength steel, the same material as the scaffolding steel pipe, 1.5m in length, 58mm in outer diameter, 3.0mm in wall thickness, and 58-2×3.0=52mm in inner diameter; the rounded corners at both ends have a radius of 3mm to avoid the risk of scratches during high-altitude operations; the outer surface is hot-dip galvanized for corrosion protection, with a zinc layer thickness of 105μm to enhance resistance to wind and rain erosion.

[0033] Inner steel pipe 2: made of the same material as outer sleeve 1, 3.0m in length, 51.1mm in outer diameter, and 3.0mm in wall thickness; the guide chamfer at the insertion end is 40° and the chamfer length is 8mm, which facilitates quick alignment and insertion during high-altitude operations; the outer surface is hot-dip galvanized with a zinc layer thickness of 102μm, which works in conjunction with outer sleeve 1 to achieve long-term corrosion protection.

[0034] Fitting clearance: The fitting clearance between the outer sleeve 1 and the inner steel pipe 2 is 52-51.1=0.9mm, which takes into account both the ease of sliding during high-altitude operations and structural stability, and avoids swaying in strong wind environments.

[0035] 2. Locating screw holes and bolt assembly Positioning screw holes 3: Six positioning screw holes 3 are evenly opened along the axial direction on the outer sleeve 1, with an adjacent spacing of 300mm and a screw hole diameter of 17mm, to meet the installation requirements of high-strength bolts; Four sets of positioning screw holes 3 are set on the inner steel pipe 2, with two symmetrically distributed in each set. The first set of positioning screw holes 3 is 300mm away from the insertion end, and the spacing between each set is 500mm, covering the effective extension range of the inner steel pipe 2.

[0036] Bolt assembly 4: Uses M16 high-strength bolts with a bolt length of 3.0+3.0+12=18mm, and is equipped with nylon lock nuts, φ16 flat washers and spring washers to improve the vibration resistance and anti-loosening ability in high-altitude environments and ensure reliable connection during long-term use of scaffolding.

[0037] 3. Adjustment and Operation Process 1) Based on the target support height of 4.5m for the pitched roof, it is calculated that the inner steel pipe 2 needs to be fully extended from the outer sleeve 1, that is, the extension length is 3.0-(1.5-0.005)=1.505m (with a 5mm safety gap). The total length of the device is 1.5+1.505=3.005m. No, correction: the length of the outer sleeve 1 is 1.5m, the length of the inner steel pipe 2 is 3.0m, and the total length when fully extended is 1.5+(3.0-0.005)=4.495m, which is close to the target height of 4.5m. 2) Two operators work together to slowly insert the inner steel pipe 2 along the axial direction of the outer sleeve 1, and use the guide chamfer to quickly align it until the annular limiting step on the inner steel pipe 2 abuts against the annular limiting protrusion inside the outer sleeve 1 to ensure that it does not come out. 3) Fine-tune the position of the inner steel tube 2 so that the sixth positioning screw hole 3 on the outer sleeve 1 is precisely aligned with the fourth group of positioning screw holes 3 on the inner steel tube 2. During the alignment process, coaxial calibration can be achieved by observing the edge of the hole. 4) Insert the bolt of bolt assembly 4 into the positioning bolt hole 3 from one side of the outer sleeve 1, and then tighten the nut after successively installing the flat washer and spring washer. The tightening torque should be controlled at 40 N·m to ensure a tight connection. 5) Use a level and measuring tape to check the verticality of the device and the total length. The total length error should be ≤4mm and the verticality deviation should be ≤2‰ to meet the support requirements of the scaffolding on the sloping roof.

[0038] 4. Application Effects This embodiment achieves a height of approximately 4.5m by matching the maximum stroke of the outer sleeve 1 and the inner steel pipe 2, eliminating the need to cut extra-long steel pipes and avoiding the problem of material loss exceeding 15% in traditional processes. The high-strength fit of the bolt assembly 4 and the symmetrical design of the positioning screw holes 3 improve the device's wind load resistance by 30%, making it suitable for the complex environment of high-altitude operations on sloping roofs, and increasing installation efficiency by more than 2 times compared to traditional processes.

[0039] Example 3 (Low-Distance Space Template Support Frame Adaptation Example) This embodiment is applicable to the construction of formwork support frames in low-ceilinged interior spaces (such as parts of underground parking garages) with a target height of 0.9m. The core structure and application are as follows: 1. Core structure and specifications Outer sleeve 1: Made of the same high-strength steel as the scaffolding steel pipe, 1.2m in length, 51mm in outer diameter (meeting the design requirement of "outer diameter greater than 51mm", with 51mm as the lower limit), 3.0mm in wall thickness, and an inner diameter of 51-2×3.0=45mm; with a 2mm radius of rounded corners at both ends to suit the confined working environment of low-ceilinged spaces; hot-dip galvanized on the outer surface with a zinc layer thickness of 85μm to meet the anti-corrosion requirements of underground humid environments.

[0040] Inner steel pipe 2: Made of the same material as outer sleeve 1, with a length of 0.9m, an outer diameter of 44.5mm, and a wall thickness of 3.0mm; the insertion end has a guide chamfer angle of 30° and a chamfer length of 5mm, which facilitates quick insertion in confined spaces; the outer surface is hot-dip galvanized with a zinc layer thickness of 85μm, and has the same anti-corrosion performance as outer sleeve 1.

[0041] Fitting clearance: The fitting clearance between the outer sleeve 1 and the inner steel pipe 2 is 45-44.5=0.5mm. This ensures both flexibility of adjustment in a low-ceilinged space and avoids support swaying caused by excessive clearance.

[0042] 2. Locating screw holes and bolt assembly Positioning screw holes 3: Four positioning screw holes 3 are opened along the axial direction on the outer sleeve 1, with an adjacent spacing of 300mm and a screw hole diameter of 14mm; Two sets of positioning screw holes 3 are set on the inner steel tube 2, with two symmetrically distributed in each set. The first set of positioning screw holes 3 is 200mm away from the insertion end, and the two sets are 350mm apart, which is suitable for short-stroke adjustment in low spaces.

[0043] Bolt assembly 4: Uses M12 high-strength bolts with a bolt length of 3.0+3.0+8=14mm, and is equipped with a nylon lock nut and a φ12 thin flat washer (1.5mm thick) to meet the compact installation requirements of low spaces and avoid the nut protruding too high and affecting the formwork laying.

[0044] 3. Adjustment and Operation Process 1) Based on the target height of 0.9m, the depth to which the inner steel pipe 2 needs to be inserted into the outer sleeve 1 is calculated to be 1.2-0.9=0.3m, that is, the length of the inner steel pipe 2 extending out of the outer sleeve 1 is 0.9-(1.2-0.3)=0m. Correction: Total length of the device = effective length of the outer sleeve 1 + extension length of the inner steel pipe 2. The target is 0.9m, and the length of the outer sleeve 1 is 1.2m. Therefore, the length of the inner steel pipe 2 inserted into the outer sleeve 1 is 1.2-0.9=0.3m, and the extension length is 0.9-(1.2-0.3)=0m. That is, the inner steel pipe 2 is partially inserted into the outer sleeve 1. 2) In a low-ceilinged space, insert the inner steel pipe 2 along the axial direction of the outer sleeve 1, with the insertion depth controlled at 0.3m. The initial positioning is achieved by observing the relative position between the port of the outer sleeve 1 and the inner steel pipe 2. 3) Fine-tune the position of the inner steel tube 2 so that the first positioning screw hole 3 on the outer sleeve 1 is precisely aligned with the first set of positioning screw holes 3 on the inner steel tube 2. Due to the limited space, a small reflector can be used to assist in observing the hole position. 4) Insert the bolts of bolt assembly 4 into the positioning screw hole 3, put on the thin flat washer and spring washer, and then tighten the nut. Use a small wrench during the tightening process to ensure that the connection is firm. 5) Use a straightedge and measuring tape to check the total length and verticality of the device. The total length error should be ≤3mm and the verticality deviation should be ≤3‰, which meets the support accuracy requirements of the low-ceiling space formwork support frame.

[0045] 4. Application Effects This embodiment achieves precise height support in low-ceilinged spaces through the short-stroke cooperation of the outer sleeve 1 and the inner steel pipe 2, eliminating the need for the traditional method of adding a scaffold and saving more than 40% of scaffold material waste. The compact structural design and convenient adjustment method allow a single operator to complete the installation in a confined space, improving construction efficiency by 1.5 times compared to traditional processes, and avoiding the problem of extra scaffold space occupying construction space.

[0046] The novel adjustable-length steel pipe system of this invention has the following advantages: This device fundamentally solves the material waste problem caused by traditional steel pipe cutting processes. Traditional construction requires on-site cutting of steel pipes to meet varying height requirements, generating significant waste and making it difficult to reuse the cut short pipes, resulting in idle resources. This device, however, employs a telescopic design between the outer sleeve and the inner steel pipe, eliminating the need for any cutting of the steel pipe. Different lengths can be achieved simply by adjusting their relative positions, completely eliminating material loss from cutting. Furthermore, all components of the device are reusable. Whether for conventional formwork support frames, scaffolding on pitched roofs, or low-ceilinged spaces, height adjustment can be achieved using the same device, significantly improving the utilization rate of steel pipe materials and reducing resource waste.

[0047] This device significantly simplifies the construction process, resulting in a substantial improvement in construction efficiency. Traditional methods require multiple cumbersome steps, including length calculation, on-site cutting, and splicing adjustments. Furthermore, the cutting operation necessitates the coordinated efforts of multiple operators, making it time-consuming and labor-intensive. In contrast, this device, through the precise engagement of positioning screw holes and bolt components, allows for easy installation and fixation simply by inserting the inner steel pipe into the outer sleeve, adjusting it to the target length, aligning the holes, and tightening the bolts. The entire operation eliminates the need for complex machinery and can be completed independently by a single person. It removes unnecessary steps such as cutting, measurement, and calibration, effectively shortening the time required for scaffolding erection and adjustment. It is particularly suitable for construction scenarios with varying heights, such as pitched roofs, enabling highly efficient progress in construction.

[0048] This device boasts exceptional ease of operation and broad adaptability to various scenarios. Its telescopic design allows for flexible and efficient length adjustment. Positioning screw holes spaced 300mm apart on the outer sleeve, combined with corresponding holes on the inner steel pipe, enable precise multi-level adjustments, meeting diverse height requirements from low-ceilinged spaces to high-altitude operations. No specialized skills training is required for operation; operators can easily align and fix the holes through visual observation, significantly lowering the barrier to entry. Whether adjusting the height of the free end of a formwork support frame or adapting to the irregular height of scaffolding on a pitched roof, this device responds quickly to needs without requiring additional auxiliary components, offering far greater adaptability than traditional cutting and splicing methods.

[0049] This device ensures construction safety while effectively controlling construction costs. Traditional cutting operations pose mechanical risks, and the resulting spliced ​​steel pipe structure has poor stability, easily leading to safety hazards. This device, however, uses the same high-strength material as traditional scaffolding steel pipes, with a uniform wall thickness of 3.0mm. Combined with bolted fastening components, it ensures the structure's load-bearing capacity and stability, reducing safety risks caused by loose splicing. Simultaneously, reduced material waste and increased construction efficiency directly lower material procurement and labor costs. No additional investment in cutting equipment and maintenance is required. Furthermore, its service life can be extended through hot-dip galvanizing for corrosion protection during long-term use, further reducing the overall life-cycle construction cost.

[0050] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A novel adjustable-length steel pipe system device, comprising an outer sleeve (1), an inner steel pipe (2), positioning screw holes (3), and a bolt assembly (4); characterized in that, The inner steel tube (2) can slide along the axial direction inside the outer sleeve (1) to form a telescopic fit structure; the positioning screw holes (3) are respectively opened through the side wall of the outer sleeve (1) and the side wall of the inner steel tube (2), and the positioning screw holes (3) on the outer sleeve (1) and the inner steel tube (2) can be aligned at different relative positions. The bolt assembly (4) includes mutually compatible bolts and matching nuts. The bolt assembly (4) is detachably inserted into the aligned positioning screw hole (3). The relative fixation of the outer sleeve (1) and the inner steel pipe (2) is achieved by the locking fit of the bolt and the matching nut. The total length of the device is precisely adjusted by the formula L=L1+L2, where L is the total length of the device, L1 is the effective working length of the outer sleeve (1), L2 is the length of the inner steel pipe (2) extending out of the outer sleeve (1), and L2∈[0,L1,L2]. 2max ], L 2max The maximum extension length of the inner steel pipe (2) is determined by the difference between the length of the outer sleeve (1) and the length of the inner steel pipe (2); By adjusting the sliding stroke of the inner steel pipe (2) in the outer sleeve (1), the positioning screw holes (3) of the two are aligned at the target position and fixed by the bolt assembly (4), thereby realizing the length adjustment of the entire steel pipe system device, which is suitable for different height requirements such as formwork support frame and scaffolding on sloping roofs in building construction.

2. The novel adjustable-length steel pipe system device according to claim 1, characterized in that, The outer sleeve (1) and the inner steel pipe (2) are made of the same high-strength steel material, and the wall thickness of both is uniformly set to 3.0mm. The axial bearing capacity of the device satisfies the formula F=σ s ·A, where σ s Let A be the yield strength of the high-strength steel, and let A be the effective stress-bearing area of ​​the device's cross-section. D is the outer diameter of the outer sleeve (1) or the outer diameter of the inner steel pipe (2), and t=3.0mm is the wall thickness to ensure that the device is subjected to uniform stress and meets the load-bearing and deformation resistance requirements in building construction. The outer diameter of the outer sleeve (1) is set to 51mm~60mm, and the gap between the inner diameter of the outer sleeve (1) and the outer diameter of the inner steel pipe (2) satisfies the formula δ=D1-D2, where δ is the fitting gap, D1 is the inner diameter of the outer sleeve (1), D2 is the outer diameter of the inner steel pipe (2), and δ∈[0.5mm,1mm]. The gap ensures that the inner steel pipe (2) slides smoothly in the outer sleeve (1) and avoids excessive shaking during the adjustment process.

3. The novel adjustable-length steel pipe system device according to claim 1, characterized in that, The outer sleeve (1) has two lengths, 1.2m or 1.5m, and the inner steel pipe (2) has a length of 0.8m to 3.0m. By combining the two specifications of outer sleeve (1) with inner steel pipes (2) of different lengths, the length can be adjusted within the range of 0.8m to 4.5m, covering most of the scaffolding height requirements in building construction.

4. The novel adjustable-length steel pipe system device according to claim 1, characterized in that, The positioning screw holes (3) on the outer sleeve (1) are evenly distributed along its axial direction, the center distance between two adjacent positioning screw holes (3) is 300mm, and the number of positioning screw holes (3) is not less than 4; the positioning screw holes (3) on the inner steel pipe (2) are provided in 2 to 4 sets, each set including 2 positioning screw holes (3) symmetrically opened on both sides of the inner steel pipe (2) to ensure the stability of the outer sleeve (1) and the inner steel pipe (2) after connection.

5. The novel adjustable-length steel pipe system device according to claim 1, characterized in that, The bolts in the bolt assembly (4) are high-strength bolts of M12 to M16 specifications. The bolt length is 8mm to 12mm longer than the sum of the wall thickness of the outer sleeve (1) and the inner steel pipe (2). The matching nut is a nylon locking nut. A flat washer and a spring washer are also provided between the nut and the outer wall of the outer sleeve (1) to further improve the anti-loosening performance and seismic resistance of the connection structure.

6. The novel adjustable-length steel pipe system device according to claim 1, characterized in that, Both ends of the outer sleeve (1) are provided with rounded corner transition structures with a radius of 2mm to 3mm; the insertion end of the inner steel pipe (2) is provided with a guide chamfer with a chamfer angle of 30° to 45° and a chamfer length of 5mm to 8mm, so as to facilitate the quick insertion of the inner steel pipe (2) into the outer sleeve (1) and at the same time avoid the sharp ends from scratching the operators or construction materials.

7. The novel adjustable-length steel pipe system device according to claim 1, characterized in that, The outer sleeve (1) has an integrally formed annular limiting protrusion (5) near one end of its interior. The outer peripheral wall of the inner steel tube (2) away from the insertion end is provided with an annular limiting step (6) that matches the annular limiting protrusion (5). When the inner steel tube (2) slides outward to the limit position, the annular limiting step (6) abuts against the annular limiting protrusion (5) to form a mechanical limit, preventing the inner steel tube (2) from completely coming out of the outer sleeve (1).

8. The novel adjustable-length steel pipe system device according to claim 1, characterized in that, The outer surfaces of the outer sleeve (1) and the inner steel pipe (2) are both hot-dip galvanized for corrosion protection. The thickness of the galvanized layer is 85μm to 120μm. The inner wall of the positioning screw hole (3) is processed by tapping after galvanizing. After tapping, it is also soaked in anti-rust oil, which significantly improves the weather resistance and corrosion resistance of the device and extends its service life in outdoor construction environment.

9. The novel adjustable-length steel pipe system device according to claim 1, characterized in that, The outer wall of the outer sleeve (1) is marked with a spacing mark and a serial number mark corresponding to the position of each positioning screw hole (3). The spacing mark indicates the center distance between adjacent positioning screw holes (3) as "300mm". The serial number mark starts from one end of the outer sleeve (1) and is marked as "1, 2, 3...". The outer wall of the inner steel pipe (2) is marked with a group number mark "1-1, 1-2..." corresponding to the position of each group of positioning screw holes (3). The operator can quickly determine the extension length of the inner steel pipe (2) by matching the serial number mark of the outer sleeve (1) with the group number mark of the inner steel pipe (2). The positioning screw holes (3) can be accurately aligned without additional measurement, which further improves the construction adjustment efficiency.

10. The novel adjustable-length steel pipe system device according to any one of claims 1-9, characterized in that, Its operation process includes the following steps: Step 1: Construction preparation. Based on the target height requirement H of the formwork support frame or scaffolding on the sloping roof in the construction, select the corresponding specifications of outer sleeve (1), inner steel pipe (2) and bolt assembly (4) in combination with the formula L=H. Check that there is no debris blocking the positioning screw holes (3) on the outer sleeve (1) and inner steel pipe (2), and that the bolts and matching nuts of the bolt assembly (4) are properly matched. Step 2: Preliminary assembly. Slowly insert the inner steel pipe (2) with the guide chamfered end into the outer sleeve (1) along the axial direction. Adjust the extension length L2 of the inner steel pipe (2) inside the outer sleeve (1) according to the target height, ensuring that L2 < L 2max Furthermore, the inner steel pipe (2) did not exceed the limiting range of the annular limiting protrusion (5); Step 3: Hole alignment. Position the holes by matching the serial number on the outer sleeve (1) with the group number on the inner steel pipe (2), or by directly observing the hole positions and finely adjusting the axial position of the inner steel pipe (2) so that any one of the positioning screw holes (3) on the outer sleeve (1) is precisely coaxially aligned with a group of positioning screw holes (3) on the inner steel pipe (2). Step 4: Tighten and fix. Insert the bolt in the bolt assembly (4) into the aligned positioning screw hole (3) from one side of the outer sleeve (1). Then, put the flat washer and spring washer on the other end of the bolt in sequence. Finally, tighten the matching nut until the bolt assembly (4) is tightly fitted with the outer wall of the outer sleeve (1) and the inner steel pipe (2) to achieve a stable connection between the three. Step 5: Verification and acceptance. Use measuring tools to verify whether the overall length L of the device meets |LH|≤5mm. At the same time, check the tightness of the bolt assembly (4) to ensure that there is no looseness. After the acceptance is qualified, the device can be installed on the top of the scaffold upright to complete the adjustment and fixation of the scaffold height.

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