A telescopic steel casing

Abstract

The utility model relates to water supply and drainage structure technical field, concretely is a telescopic steel sleeve, including the first steel sleeve component and second steel sleeve component of mutual socketing cooperation, the lower extreme of first steel sleeve component is inserted with second steel sleeve component and cooperates, the upper end of first steel sleeve component is connected with narrowing section, and the upper end of narrowing section is installed with upper flange ring. In this telescopic steel sleeve, the socketing cooperation structure of first steel sleeve component and second steel sleeve component realizes the flexible telescopic adjustment of length direction. In combination with the design of the enlarged inner diameter of the lower end of the first steel sleeve component, both the telescopic adjustment requirement and the stability of socket connection can be met. In actual construction, when the composite floor extends beyond the edge of the beam or the concrete causes the formwork to deviate due to the swelling of the mold, the steel sleeve can be adjusted synchronously with the formwork by the relative telescoping of the two components, effectively avoiding the problem that the traditional fixed-length sleeve is wrapped and buried by concrete due to the inability to adapt to the deviation.

Description

Technical Field

[0001] This utility model relates to the field of water supply and drainage structure technology, specifically to a retractable steel sleeve. Background Technology

[0002] In the field of water supply and drainage construction for prefabricated residential buildings, water supply pipes penetrating beams is an unavoidable and crucial step in the project implementation. Prefabricated construction, a construction model vigorously promoted by the industry in recent years, has the core advantage of transferring a large amount of traditional on-site work to factories for component prefabrication, followed by transportation to the site for assembly and installation, significantly improving construction efficiency and project quality stability. However, water supply and drainage construction under this model, especially the pre-embedding of steel sleeves at beam penetration points, faces unique and urgent technical challenges. In the pre-installation and embedding of through-beam sleeves in building water supply and drainage engineering, traditional construction methods generally use welded steel pipes of fixed length as steel sleeves. In practice, construction workers first need to cut the welded steel pipes to a specific length (this length must be strictly shorter than the beam width), then weld lugs to both ends of the steel pipe, and use these lugs to fix the steel sleeve to the beam formwork before concrete pouring. While this fixed-length steel sleeve design can meet basic usage requirements in traditional cast-in-place construction, its limitations and drawbacks become increasingly apparent when applied to prefabricated building scenarios. On the one hand, the composite floor slab structure widely used in prefabricated buildings, which consists of precast slabs and cast-in-place reinforced concrete layers, often extends beyond the beam edges during assembly. This construction phenomenon directly interferes with the positioning and identification of pre-embedded steel sleeves, making it difficult for construction workers to accurately locate the pre-embedded fixed-length steel sleeves in subsequent processes. On the other hand, formwork bulging is prone to occur during concrete pouring, where excessive lateral pressure from the concrete on the formwork causes deformation, further exacerbating the positional displacement of the fixed-length steel sleeves, and even resulting in the steel sleeves being encased or buried by concrete. The aforementioned problems not only require construction workers to spend a significant amount of time and manpower locating the pre-embedded sleeves during subsequent pipeline installation, severely reducing construction efficiency and increasing labor costs, but also may necessitate additional chiseling work due to inaccurate positioning, damaging the structural integrity of the beams and affecting the overall load-bearing capacity of the building. Furthermore, because fixed-length steel sleeves cannot accommodate adjustments to the formwork, after the formwork is removed, the sleeve portion often appears partially hidden inside the concrete, affecting the aesthetic appearance of the project and creating potential hazards for subsequent pipeline inspection and maintenance. Utility Model Content

[0003] The purpose of this utility model is to provide a telescopic steel sleeve to solve the problem that the design concept of fixed-length steel sleeve mentioned in the background art can meet the basic needs in traditional cast-in-place construction, but its limitations and drawbacks become increasingly prominent when applied to prefabricated building scenarios.

[0004] To achieve the above objectives, this utility model provides a telescopic steel sleeve, including a first steel sleeve component and a second steel sleeve component that can be inserted and fitted together. The lower end of the first steel sleeve component is inserted and fitted with the second steel sleeve component. The upper end of the first steel sleeve component is connected to a narrowing section, and an upper flange ring is installed at the upper end of the narrowing section. The lower end of the second steel sleeve component is installed with a lower flange ring. The upper flange ring is connected to the upper beam template nail hole, and the lower flange ring is connected to the lower beam template nail hole.

[0005] This design splits the steel sleeve into a first steel sleeve component and a second steel sleeve component that can be interlocked, allowing for adjustable length through the interlocking fit of the two components. Simultaneously, upper and lower flange rings are respectively installed at the ends of the two components. Direct connection between the flange rings and the nail holes in the beam formwork replaces the traditional lug fixing method, achieving stable assembly of the sleeve and the formwork. Based on the logic of "modular disassembly + convenient fixing," this design solves both the length adaptation problem and simplifies the installation process.

[0006] Preferably, a transition section is provided between the first steel sleeve component and the narrowing section, wherein the diameter of the narrowing section is smaller than the diameter of the first steel sleeve component.

[0007] This feature includes a transition section between the first steel sleeve component and the narrowing section, with the diameter of the narrowing section being smaller than that of the first steel sleeve component. The purpose of the transition section is to achieve a smooth connection between the first steel sleeve component (large diameter) and the narrowing section (small diameter), avoiding stress concentration caused by abrupt diameter changes. The small diameter design of the narrowing section is to accommodate the subsequent installation of the upper flange ring, while also reducing the space occupied by the sleeve and avoiding interference with other structural elements of the beam (such as reinforcing bars).

[0008] Preferably, the upper end of the second steel sleeve component is provided with an interface end, which is inserted into the first steel sleeve component, and a sealing gasket is installed on the outer wall of the interface end.

[0009] This design incorporates an interface end at the upper end of the second steel sleeve component, the size of which matches the enlarged inner diameter at the lower end of the first steel sleeve component. This ensures that the interface end can be smoothly inserted into the first steel sleeve component, achieving precise insertion between the two components. Simultaneously, a sealing gasket is installed on the outer wall of the interface end. The elastic deformation of the sealing gasket fills the gap after insertion, preventing cement grout from seeping into the channel. This design balances the precision of the insertion with the reliability of the seal.

[0010] Preferably, the outer wall of the second steel sleeve component is equipped with a slider, and the inner wall of the first steel sleeve component is vertically provided with a guide groove, and the slider slides in cooperation with the guide groove.

[0011] This design incorporates a slider on the outer wall of the second steel sleeve component and a vertical guide groove on the inner wall of the first steel sleeve component, with the slider sliding in conjunction with the guide groove. The guide groove provides a vertical sliding track for the slider, restricting its movement to vertical only, thereby constraining the relative motion direction of the two components. This ensures that expansion and contraction occur only in the length direction, preventing circumferential rotation or lateral offset of the two components. This design achieves precise control of the motion direction through structural limiting.

[0012] Preferably, the slider includes a fixed seat welded to the second steel sleeve component, the fixed seat having a groove on its front side, and a damping pad being provided in the groove, the outer surface of the damping pad contacting the inner wall of the first steel sleeve component to provide frictional resistance.

[0013] This slider is composed of a fixed seat welded to the second steel sleeve component and a damping pad within a slot. The outer surface of the damping pad contacts the inner wall of the first steel sleeve component. The fixed seat ensures a stable connection between the slider and the second steel sleeve component. The damping pad utilizes its material properties (such as the high coefficient of friction of rubber) to generate frictional resistance with the inner wall of the first steel sleeve component. This frictional resistance can counteract external forces such as construction vibration and concrete impact, allowing the two components to remain in a fixed position after expansion and contraction adjustments, preventing self-slippage.

[0014] Preferably, a spring plate is installed on the back of the damping pad, which increases the force between the damping pad and the inner wall of the first steel sleeve component.

[0015] This feature involves installing a spring plate on the back of the damping pad. The spring plate has elastic deformation capability and, in its natural state, exerts an outward pushing force on the damping pad, ensuring that the damping pad remains tightly fitted to the inner wall of the first steel sleeve component, thus increasing the contact pressure between the damping pad and the inner wall. According to the friction formula (friction force = pressure × coefficient of friction), increased contact pressure directly increases the frictional resistance between the damping pad and the inner wall, further enhancing the positioning effect.

[0016] Preferably, the lower end of the first steel sleeve component has an enlarged inner diameter range that is 1-3 mm larger than the outer diameter of the second steel sleeve component, so as to ensure that both expansion and contraction adjustment can be achieved when the two are fitted together, and the stability of the connection can be guaranteed.

[0017] This design sets the inner diameter of the lower end of the first steel sleeve component to be 1-3mm larger than the outer diameter of the second steel sleeve component. This gap size has been precisely calculated—if the gap is too small, the two components will be too tightly connected, preventing smooth expansion and contraction; if the gap is too large, the connection between the two components will be loose, easily leading to lateral displacement and swaying. A gap of 1-3mm satisfies the space requirements when the two components expand and contract relative to each other, while also limiting the lateral displacement of the two components through a smaller gap, achieving a balance between expansion and contraction and stability.

[0018] Preferably, the width of the upper flange ring and the lower flange ring is 15-25mm to ensure sufficient fixing area when fixed to the beam formwork through the nail holes, preventing loosening of the fixing.

[0019] This setting sets the width of the upper and lower flange rings to 15-25mm. This width range ensures sufficient fixing area when the flange rings contact the beam formwork. According to the pressure formula (pressure = force / area), under the same external force, the larger the contact area, the smaller the pressure on the formwork, which can avoid local deformation of the formwork due to excessive pressure. At the same time, sufficient fixing area can accommodate multiple nail holes, making the fixing points more evenly distributed, dispersing the external force on the sleeve, and improving the fixing reliability.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows: This expandable steel sleeve achieves flexible length adjustment through the socket-fitting structure of the first and second steel sleeve components. Combined with the design of an enlarged inner diameter at the lower end of the first steel sleeve component (1-3mm larger than the outer diameter of the second steel sleeve component), it satisfies both the need for expansion and adjustment and ensures the stability of the socket connection. In actual construction, when the composite floor slab extends beyond the beam edge or the concrete bulges causing formwork displacement, the steel sleeve can adjust synchronously with the formwork through the relative expansion and contraction of the two components, effectively avoiding the problem of traditional fixed-length sleeves being encased or buried by concrete due to their inability to adapt to displacement. After the formwork is removed, the sleeve is fully exposed, improving the aesthetic appearance of the project and providing a clear positioning benchmark for subsequent pipe installation, eliminating the need for additional chiseling work and ensuring the integrity of the beam structure. Compared to the complex operation of traditional steel sleeves, which require welding lugs and precise cutting to fix the length, this telescopic steel sleeve is designed to connect directly to the beam formwork nail holes via upper and lower flange rings. This eliminates the lug welding process, and during construction, it can be fixed simply by nailing through the flange ring holes, making the operation simple and convenient. Furthermore, its telescopic nature eliminates the need for construction personnel to accurately calculate the beam width to cut the sleeve length, reducing the time and material waste associated with measurement and cutting. In addition, the sleeve is fully exposed after the formwork is removed, avoiding the problem of traditional sleeves requiring significant manpower to locate due to concealment. This significantly shortens the construction cycle, reduces labor costs, and substantially improves the overall efficiency of pre-embedded beam sleeve construction for water supply and drainage systems in prefabricated buildings. In terms of structural stability, the sliding contact between the slider on the outer wall of the second steel sleeve component and the guide groove on the inner wall of the first steel sleeve component provides precise vertical guidance for the expansion and contraction of the two components, preventing offset and jamming during expansion and contraction. It also enhances the overall integrity of the connection between the two components, avoiding the swaying problems common in traditional socket structures. Simultaneously, the contact between the damping pad inside the slider and the inner wall of the first steel sleeve component generates stable frictional resistance under the force of the spring plate, ensuring that the two components maintain a fixed position after expansion and contraction adjustments, preventing the sleeve from shifting due to construction vibration or concrete pouring impact. Furthermore, the sealing gasket on the outer wall of the interface end of the second steel sleeve component fills the gap when the two components are socketed, effectively preventing cement slurry from seeping into the sleeve during concrete pouring, ensuring the cleanliness of the sleeve's interior, providing favorable conditions for subsequent pipeline installation, and further improving the reliability of construction quality. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a schematic diagram of the internal structure of the present invention; Figure 3 This is a schematic diagram of the slider structure in this utility model; The meanings of the labels in the diagram are as follows: 1. First steel sleeve component; 11. Transition section; 12. Narrowing section; 13. Upper flange ring; 14. Guide groove; 2. Second steel sleeve component; 21. Interface end; 22. Lower flange ring; 23. Sealing gasket; 24. Sliding block; 241. Fixed seat; 242. Damping pad; 243. Spring plate. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] This utility model provides a retractable steel sleeve, such as Figure 1 , Figure 2As shown, it includes a first steel sleeve component 1 and a second steel sleeve component 2 that can be inserted and fitted together. The lower end of the first steel sleeve component 1 is inserted and fitted with the second steel sleeve component 2. The upper end of the first steel sleeve component 1 is connected to a narrowing section 12. An upper flange ring 13 is installed at the upper end of the narrowing section 12. A lower flange ring 22 is installed at the lower end of the second steel sleeve component 2. The upper flange ring 13 is connected to the upper beam template nail hole, and the lower flange ring 22 is connected to the lower beam template nail hole.

[0024] The steel sleeve is disassembled into a first steel sleeve component 1 and a second steel sleeve component 2 that can be interlocked. The overall length of the steel sleeve is adjustable by the interlocking fit between the lower end of the first steel sleeve component 1 and the second steel sleeve component 2. Simultaneously, an upper flange ring 13 is installed at the upper end of the first steel sleeve component 1 via a narrowing section 12, and a lower flange ring 22 is installed at the lower end of the second steel sleeve component 2. Direct connection between the upper flange ring 13 and the nail holes of the upper side beam template, and between the lower flange ring 22 and the nail holes of the lower side beam template, replaces the traditional lug fixing method, achieving stable assembly of the steel sleeve and the beam template. This design, based on the logic of "modular disassembly + convenient fixing," solves both the length adaptation problem and simplifies the installation process. On the one hand, the socket joint between the first steel sleeve component 1 and the second steel sleeve component 2 breaks the limitation of traditional fixed-length sleeves, allowing the steel sleeve to flexibly adjust its length according to the offset of the beam formwork, such as the extension of the composite floor slab or the displacement of the formwork caused by the expansion of the concrete formwork, thus avoiding the steel sleeve being wrapped by the concrete. On the other hand, the connection method between the upper flange ring 13, the lower flange ring 22 and the nail holes of the formwork eliminates the lug welding process. During construction, it is only necessary to fix the upper flange ring 13 and the lower flange ring 22 through the nail holes, which is convenient to operate, greatly reduces labor costs and construction complexity, and at the same time ensures the installation stability of the steel sleeve during the concrete pouring process, providing a basic guarantee for the subsequent installation of water supply and drainage pipelines.

[0025] In this embodiment, as Figure 1 , Figure 2 As shown, a transition section 11 is provided between the first steel sleeve component 1 and the narrowing section 12, and the diameter of the narrowing section 12 is smaller than the diameter of the first steel sleeve component 1.

[0026] A transition section 11 is provided between the first steel sleeve component 1 and the narrowing section 12, and the diameter of the narrowing section 12 is smaller than the diameter of the first steel sleeve component 1. The function of the transition section 11 is to achieve a smooth connection between the large diameter of the first steel sleeve component 1 and the small diameter of the narrowing section 12, avoiding stress concentration caused by abrupt diameter changes; the small diameter design of the narrowing section 12 is to accommodate the subsequent installation of the upper flange ring 13, while reducing the space occupied by the upper part of the steel sleeve and avoiding interference with other structures of the beam, such as reinforcing bars. The transition section 11 effectively disperses the stress at the connection between the first steel sleeve component 1 and the narrowing section 12, preventing cracking at this part due to long-term use or construction vibration, and improving the overall structural strength of the steel sleeve. The small diameter design of the narrowing section 12 not only makes the installation of the upper flange ring 13 more snug and reduces the installation gap, but also avoids the densely reinforced areas in the beam, reducing the risk of collision between the steel sleeve and the reinforcing bars during the pre-embedding, improving the convenience of construction, and at the same time ensuring a reasonable spatial layout of the steel sleeve in the beam without affecting the structural performance of the beam.

[0027] Specifically, such as Figure 1 , Figure 2 As shown, the upper end of the second steel sleeve component 2 is provided with an interface end 21, which is inserted into the first steel sleeve component 1, and a sealing gasket 23 is installed on the outer wall of the interface end 21.

[0028] The upper end of the second steel sleeve component 2 is provided with an interface end 21. The size of the interface end 21 matches the enlarged inner diameter of the lower end of the first steel sleeve component 1, ensuring that the interface end 21 can be smoothly inserted into the first steel sleeve component 1, achieving precise insertion between the first steel sleeve component 1 and the second steel sleeve component 2. At the same time, a sealing gasket 23 is installed on the outer wall of the interface end 21. The elastic deformation of the sealing gasket 23 fills the gap between the first steel sleeve component 1 and the second steel sleeve component 2 after insertion, blocking the cement grout seepage channel. This design takes into account both the precision of insertion and the reliability of sealing. The precise insertion and engagement of the interface end 21 with the first steel sleeve component 1 further ensures the smoothness of the expansion and contraction adjustment of the first steel sleeve component 1 and the second steel sleeve component 2, avoiding jamming and offset problems caused by size mismatch, and improving the stability of expansion and contraction adjustment; the sealing gasket 23 effectively solves the problem of cement slurry seepage that is prone to occur in traditional socket sleeves, prevents the inside of the steel sleeve from being blocked by slurry, ensures the cleanliness of the inside of the steel sleeve, and provides a smooth passage for subsequent water supply and drainage pipeline installation. There is no need to clean the inside of the steel sleeve before pipeline installation, saving construction time and improving construction quality.

[0029] Furthermore, such as Figure 1 , Figure 2 As shown, a slider 24 is installed on the outer wall of the second steel sleeve component 2, and a guide groove 14 is vertically provided on the inner wall of the first steel sleeve component 1. The slider 24 and the guide groove 14 slide in cooperation.

[0030] A slider 24 is installed on the outer wall of the second steel sleeve component 2, and a guide groove 14 is vertically provided on the inner wall of the first steel sleeve component 1. The slider 24 slides in conjunction with the guide groove 14. The guide groove 14 provides a vertical sliding track for the slider 24, restricting the slider 24 to move only vertically, thereby constraining the relative movement direction of the first steel sleeve component 1 and the second steel sleeve component 2, ensuring that expansion and contraction only occur in the length direction, and avoiding circumferential rotation or lateral offset of the two components. This design achieves precise control of the movement direction through structural limiting. The cooperation between the slider 24 and the guide groove 14 provides a clear vertical guide for the expansion and contraction of the first steel sleeve component 1 and the second steel sleeve component 2, completely solving the problems of circumferential rotation and lateral offset that are prone to occur during the expansion and contraction of traditional socket sleeves, ensuring that the steel sleeve always maintains axial consistency and does not become skewed; at the same time, the sliding fit structure reduces the frictional resistance during the expansion and contraction of the first steel sleeve component 1 and the second steel sleeve component 2, making the expansion and contraction adjustment more effortless and smooth. Construction personnel can easily adjust the length of the steel sleeve according to the offset of the template, improving the convenience of construction, and enhancing the overall integrity of the connection between the two components, avoiding structural loosening during the expansion and contraction process.

[0031] Furthermore, such as Figure 3 As shown, the slider 24 includes a fixed seat 241 welded to the second steel sleeve component 2. The front of the fixed seat 241 is slotted, and a damping pad 242 is provided in the slot. The outer surface of the damping pad 242 contacts the inner wall of the first steel sleeve component 1 to provide frictional resistance.

[0032] The slider 24 includes a fixed seat 241 welded to the second steel sleeve component 2. The fixed seat 241 has a slot on its front side, and a damping pad 242 is provided in the slot. The outer surface of the damping pad 242 contacts the inner wall of the first steel sleeve component 1. The fixed seat 241 achieves a stable connection between the slider 24 and the second steel sleeve component 2. The damping pad 242 utilizes its material properties, such as the high coefficient of friction of rubber, to generate frictional resistance with the inner wall of the first steel sleeve component 1. This frictional resistance can offset external forces such as construction vibration and concrete impact, so that the first steel sleeve component 1 and the second steel sleeve component 2 can remain in a fixed position after expansion and contraction adjustment, and will not slide on their own. The frictional resistance between the damping pad 242 and the inner wall of the first steel sleeve component 1 provides a reliable positioning function for the first steel sleeve component 1 and the second steel sleeve component 2, preventing the steel sleeve from automatically expanding or shifting due to external forces during concrete pouring and vibration, construction personnel operation, etc., ensuring that the steel sleeve is always in the preset position and improving the accuracy of pre-embedded positioning; at the same time, the damping pad 242 has a certain degree of elasticity, which can play a buffering role when the first steel sleeve component 1 and the second steel sleeve component 2 expand and contract, reducing the collision and wear of the two components during sliding, extending the service life of the steel sleeve, and the friction positioning does not require an additional locking device, simplifying the structure while ensuring positioning reliability.

[0033] Furthermore, such as Figure 3 As shown, a spring plate 243 is installed on the back of the damping pad 242, and the spring plate 243 increases the force between the damping pad 242 and the inner wall of the first steel sleeve component 1.

[0034] A spring plate 243 is installed on the back of the damping pad 242. The spring plate 243 has elastic deformation capability and will generate an outward pushing force on the damping pad 242 in its natural state, so that the damping pad 242 is always in close contact with the inner wall of the first steel sleeve component 1, increasing the contact pressure between the damping pad 242 and the inner wall of the first steel sleeve component 1. According to the friction formula, friction force = pressure × coefficient of friction, the increase in contact pressure can directly increase the frictional resistance between the damping pad 242 and the inner wall of the first steel sleeve component 1, further enhancing the positioning effect. The elastic force of the spring plate 243 makes the contact between the damping pad 242 and the inner wall of the first steel sleeve component 1 more compact, significantly increasing the contact pressure and frictional resistance. Compared with the structure without the spring plate 243, the positioning stability is greatly enhanced. Even when faced with large construction vibrations or concrete impacts, the first steel sleeve component 1 and the second steel sleeve component 2 can maintain a fixed position and will not expand or contract on their own. At the same time, the spring plate 243 can compensate for the wear of the damping pad 242 after long-term use. When the thickness of the damping pad 242 decreases due to wear, the elastic force of the spring plate 243 can push the damping pad 242 to continue to adhere to the inner wall of the first steel sleeve component 1, ensuring that the frictional resistance is always within the effective range, extending the service life of the damping pad 242, and ensuring long-term reliable positioning function.

[0035] Furthermore, the lower end of the first steel sleeve component 1 has an enlarged inner diameter range that is 1-3 mm larger than the outer diameter of the second steel sleeve component 2, so as to ensure that both expansion and contraction adjustment can be achieved when the two are fitted together, while also ensuring the stability of the connection.

[0036] The inner diameter of the lower end of the first steel sleeve component 1 is set to be 1-3 mm larger than the outer diameter of the second steel sleeve component 2. This gap size is precisely calculated—if the gap is too small, the first steel sleeve component 1 and the second steel sleeve component 2 will be inserted too tightly, preventing smooth expansion and contraction; if the gap is too large, the connection between the first steel sleeve component 1 and the second steel sleeve component 2 will be loose, easily leading to lateral displacement and swaying. The 1-3 mm gap satisfies the space requirements when the two components expand and contract relative to each other, while also limiting the lateral displacement of the two components through a smaller gap, achieving a balance between expansion and contraction and stability. A reasonable gap of 1-3mm ensures that the first steel sleeve component 1 and the second steel sleeve component 2 can be easily adjusted for expansion and contraction when they are fitted together, meeting the length adaptation requirements when the template is offset. At the same time, it can effectively avoid the problem of lateral swaying and offset of the two components due to excessive gap, thus ensuring the stability of the overall steel sleeve structure. Meanwhile, the smaller gap can also reduce the possibility of cement slurry seepage. When used with sealing gasket 23, the effect is even better, further improving the sealing and protection capability of the steel sleeve. Moreover, the uniform gap size facilitates standardized production in the factory, reduces processing difficulty, and ensures consistent product quality.

[0037] Furthermore, the upper flange ring 13 and the lower flange ring 22 are 15-25mm wide to ensure sufficient fixing area when fixed to the beam formwork through the nail holes, preventing loosening of the fixation.

[0038] The widths of the upper flange ring 13 and the lower flange ring 22 are set to 15-25mm. This width range ensures sufficient fixing area when the upper flange ring 13 and the lower flange ring 22 contact the beam formwork. According to the pressure formula Pressure = Force / Area, under the same external force, the larger the contact area, the smaller the pressure on the beam formwork, which can avoid local deformation of the beam formwork due to excessive pressure. At the same time, sufficient fixing area can accommodate multiple nail holes, making the fixing points more evenly distributed, dispersing the external force on the steel sleeve, and improving the fixing reliability. The 15-25mm flange ring width provides ample contact area for fixing the steel sleeve to the beam formwork. Combined with the even distribution of multiple nail holes, this disperses the fixing force over a larger area of ​​the beam formwork, preventing deformation or damage due to excessive localized stress and protecting the beam formwork structure. Simultaneously, the sufficient fixing area and evenly distributed fixing points ensure that the steel sleeve maintains a stable installation position during concrete pouring, vibration, and other construction processes, preventing loosening or displacement. This further improves the positioning accuracy of the embedded sleeve, providing a stable foundation for subsequent pipe installation. Furthermore, this width is compatible with common beam formwork thicknesses, offering strong versatility and suitability for various prefabricated building beam construction scenarios.

[0039] When using the telescopic steel sleeve of this utility model, before construction, it is necessary to confirm that the first steel sleeve component 1, the second steel sleeve component 2, and the matching sealing gasket 23, slider 24 including fixed seat 241, damping pad 242, spring plate 243, upper flange ring 13, lower flange ring 22 and other components are intact, and the difference between the enlarged inner diameter of the lower end of the first steel sleeve component 1 and the outer diameter of the second steel sleeve component 2 meets the requirement of 1-3mm to ensure smooth insertion and insertion. First, the sealing gasket 23 is fitted and fixed on the outer wall of the interface end 21 of the second steel sleeve component 2. Then, the slider 24 is welded to the preset position on the outer wall of the second steel sleeve component 2 through the fixing seat 241, ensuring that the position of the slider 24 corresponds to the guide groove 14 on the inner wall of the first steel sleeve component 1. Then, the interface end 21 of the second steel sleeve component 2 is inserted into the lower end of the first steel sleeve component 1, so that the slider 24 is embedded in the guide groove 14, completing the initial insertion and assembly of the two core components. At this time, the damping pad 242 is in close contact with the inner wall of the first steel sleeve component 1 under the thrust of the spring plate 243, generating initial frictional resistance. According to the prefabricated building beam construction drawings, determine the pre-embedded position of the through-beam sleeve, and place the assembled telescopic steel sleeve at the preset position of the beam formwork; according to the spacing between the upper and lower sides of the beam formwork, push the first steel sleeve component 1 or the second steel sleeve component 2 along the guide groove 14 to adjust the overall length of the sleeve, so that the upper flange ring 13 fits against the inner wall of the upper beam formwork and the lower flange ring 22 fits against the inner wall of the lower beam formwork. During the adjustment process, the slider 24 slides vertically along the guide groove 14 to ensure that the sleeve does not deviate axially. After the adjustment is completed, the frictional resistance between the damping pad 242 and the inner wall of the first steel sleeve component 1 temporarily fixes the two components to prevent length rebound. Use fasteners such as nails to pass through the nail holes on the upper flange ring 13 and the lower flange ring 22, and fix them to the upper and lower side beam templates respectively. Since the flange ring width is 15-25mm, the fixing area is sufficient to ensure that the sleeve is firmly connected to the template and does not loosen, while avoiding excessive local stress on the template during fixing, which could lead to deformation. During concrete pouring, if the beam formwork shifts vertically due to the overlapping floor slab extending beyond the beam edge or the lateral pressure of the concrete, the formwork will cause the upper flange ring 13 or lower flange ring 22 to shift synchronously, thereby pushing the first steel sleeve component 1 or the second steel sleeve component 2 to slide relative to each other along the guide groove 14, achieving adaptive adjustment of the sleeve length. For example, when the upper formwork shifts upward, it will pull the first steel sleeve component 1 upward, and the slider 24 will slide upward along the guide groove 14. The damping pad 242 will rub against the inner wall of the first steel sleeve component 1. Because the spring plate 243 continuously provides thrust, the frictional resistance always exists. After adjustment, the sleeve can be stabilized at the new length position, avoiding the sleeve being squeezed and deformed or buried by the concrete due to the formwork shift. During concrete pouring, the sealing gasket 23 fills the socket gap between the first steel sleeve component 1 and the second steel sleeve component 2, effectively preventing cement slurry from seeping into the sleeve and ensuring the cleanliness of the inner wall of the sleeve. At the same time, the cooperation between the guide groove 14 and the slider 24 restricts the lateral displacement of the two components, preventing the sleeve from tilting under the impact of concrete and ensuring the accuracy of the pre-embedded position. After the concrete of the beam is poured and reaches the design strength, the upper and lower side beam formwork is removed. At this time, the upper flange ring 13 and the lower flange ring 22 are detached from the formwork. The telescopic steel sleeve is not covered by concrete because it adapts to the formwork during the pouring process. After the formwork is removed, it can be fully exposed, with a good appearance, and there is no need to find or remove the concrete. When installing water supply and drainage pipes, the pipes can be directly passed through the retractable steel sleeve. Since there is no slurry blockage inside the sleeve, the pipes can be passed through smoothly. If maintenance is required on the pipes or sleeves later, the sleeve length can be adjusted again along the guide groove 14 to provide space for maintenance operations and improve the convenience of later maintenance.

[0040] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model 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 utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A retractable steel sleeve, characterized in that: It includes a first steel sleeve component (1) and a second steel sleeve component (2) that can be inserted and fitted together. The lower end of the first steel sleeve component (1) is inserted and fitted with the second steel sleeve component (2). The upper end of the first steel sleeve component (1) is connected to a narrowing section (12). The upper end of the narrowing section (12) is equipped with an upper flange ring (13). The lower end of the second steel sleeve component (2) is equipped with a lower flange ring (22). The upper flange ring (13) is connected to the upper beam template nail hole, and the lower flange ring (22) is connected to the lower beam template nail hole. A transition section (11) is provided between the first steel sleeve component (1) and the narrowing section (12), and the diameter of the narrowing section (12) is smaller than the diameter of the first steel sleeve component (1); The upper end of the second steel sleeve component (2) is provided with an interface end (21), the interface end (21) is inserted into the first steel sleeve component (1), and a sealing gasket (23) is installed on the outer wall of the interface end (21). The outer wall of the second steel sleeve component (2) is equipped with a slider (24), and the inner wall of the first steel sleeve component (1) is vertically provided with a guide groove (14). The slider (24) and the guide groove (14) are in sliding cooperation. The slider (24) includes a fixed seat (241) welded to the second steel sleeve component (2). The fixed seat (241) has a slot on its front side, and a damping pad (242) is provided in the slot. The outer surface of the damping pad (242) contacts the inner wall of the first steel sleeve component (1) to provide frictional resistance. A spring plate (243) is installed on the back of the damping pad (242), and the spring plate (243) increases the force between the damping pad (242) and the inner wall of the first steel sleeve component (1).

2. The telescopic steel sleeve according to claim 1, characterized in that: The inner diameter of the lower end of the first steel sleeve component (1) is 1-3 mm larger than the outer diameter of the second steel sleeve component (2) to ensure that both can be adjusted for expansion and contraction when they are fitted together, and to ensure the stability of the connection.

3. The telescopic steel sleeve according to claim 1, characterized in that: The width of the upper flange ring (13) and the lower flange ring (22) is 15-25mm to ensure sufficient fixing area when fixed to the beam template through the nail holes, and to prevent loosening of the fixing.

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