UPVC pipe and cast iron pipe high-efficiency connecting structure

Abstract

The utility model discloses a UPVC pipeline and cast iron pipeline efficient connecting structure, including metal pipe and plastic pipe, the pipe mouth outer periphery of metal pipe is equipped with flange edge, and the inner periphery is equipped with the socket structure, the socket structure is equipped with the sealing groove in, be equipped with three element ethylene propylene rubber strip in the sealing groove, the outer periphery of plastic pipe is equipped with metal flange plate, plastic pipe is inserted in the socket structure, metal flange plate with the flange edge is connected fastening through a plurality of bolts, extrude three element ethylene propylene rubber strip and form sealing structure between plastic pipe with metal pipe, and the upper part of three element ethylene propylene rubber strip is located between the flange edge with metal flange plate. This connecting structure can solve the interface loose problem caused by the thermal expansion and cold shrinkage difference of cast iron and UPVC pipe, improve the deformation adaptation ability of connecting structure, and moreover, simplify the connecting procedure, reduce the dependence on professional welding, bonding process, and improve the construction efficiency of old community reconstruction.

Description

Technical Field

[0001] This utility model relates to the field of pipe connection technology of different materials, specifically to an efficient connection structure between UPVC pipe and cast iron pipe. Background Technology

[0002] In the renovation of water supply and drainage systems in old residential communities, upgrading the piping system faces the core challenges of material compatibility and connection reliability. Traditional drainage systems mostly use cast iron pipes, which, while possessing high strength and durability, suffer from drawbacks such as heavy weight, susceptibility to corrosion, and high maintenance costs. UPVC pipes, on the other hand, have become the mainstream alternative material in renovations due to their advantages such as light weight, corrosion resistance, low cost, and convenient installation. However, significant differences in thermal expansion and contraction occur when the ambient temperature changes, easily leading to problems such as loosening and leakage at the connection joints.

[0003] Meanwhile, the renovation of old residential communities is subject to strict limitations on construction efficiency and space. It is necessary to ensure the long-term sealing and stability of the connection structure while adapting to complex on-site conditions to avoid delays caused by complex connection processes. Therefore, developing a high-efficiency connection structure that can adapt to the properties of two materials and resist the effects of thermal expansion and contraction has become a key requirement for solving the pain points of water supply and drainage renovation in old residential communities.

[0004] Traditionally, the connection between cast iron pipes and UPVC pipes has involved welding flanges to the cast iron pipe, bonding flanges to the UPVC pipe, sealing with rubber ring clamps, or direct bonding. This method suffers from problems such as poor sealing, low durability, and weak resistance to displacement. Especially in environments with frequent temperature changes or foundation settlement, the joints are prone to loosening and leakage. Furthermore, traditional connection structures have poor adaptability to axial deviations in the pipes, increasing installation difficulty and potentially affecting drainage.

[0005] Poor adaptability to thermal expansion and contraction: In traditional flange connections, cast iron flanges and UPVC flanges are rigidly connected to their respective pipe materials. However, the thermal expansion coefficients of the two materials differ significantly. When the ambient temperature changes, the expansion and contraction deformation of the pipe cannot be buffered by the connection structure, which can easily lead to uneven stress on the rubber gasket, resulting in loosening of the joint and failure of the seal.

[0006] Insufficient sealing durability: Existing solutions mostly use ordinary natural rubber or nitrile rubber gaskets. These materials have weak resistance to aging and acid and alkali corrosion. Under long-term immersion in sewage media and temperature cycling, they are prone to hardening and cracking, which leads to rapid decline in sealing performance and a significant increase in leakage risk over time.

[0007] Construction efficiency is low: It is necessary to weld flanges on cast iron pipes and bond flanges on UPVC pipes separately. Both processes require professional tools and time. The welding process is easily restricted by the site space, and after bonding, it is necessary to wait for the adhesive to fully cure, which seriously affects the construction progress of the renovation of old residential areas.

[0008] Limited connection stability: UPVC flanges have lower material strength than cast iron flanges. When subjected to bolt tightening force and pipeline stress for a long time, the flange surface is prone to deformation or cracking, resulting in a decrease in the overall stability of the connection structure. Summary of the Invention

[0009] The purpose of this invention is to address the problems existing in the prior art by providing an efficient connection structure between UPVC pipes and cast iron pipes.

[0010] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A high-efficiency connection structure between UPVC pipe and cast iron pipe includes a metal pipe and a plastic pipe to be connected. The metal pipe has a flange on its outer periphery and a socket structure on its inner periphery. The socket structure has a sealing groove, and an EPDM rubber strip is placed in the sealing groove. The axial dimension of the EPDM rubber strip is greater than the axial depth of the sealing groove. The plastic pipe is fitted with a metal flange on its outer periphery and is inserted into the socket structure. The metal flange is fastened to the flange by a number of bolts. The EPDM rubber strip is squeezed to form a sealing structure between the plastic pipe and the metal pipe, and the upper part of the EPDM rubber strip is located between the flange and the metal flange. This efficient connection structure between UPVC and cast iron pipes combines the rigid fixation of steel flanges with the elastic sealing of EPDM rubber strips, rather than simply relying on the rigid fit between the flange face and ordinary rubber gaskets, forming a "rigid-flexible" adaptable structure. It can solve the problem of loosening of the interface caused by the difference in thermal expansion and contraction between cast iron and UPVC pipes, and improve the deformation adaptability of the connection structure. Moreover, it simplifies the connection process, reduces the reliance on professional welding and bonding processes, and improves the construction efficiency of old community renovation.

[0011] Furthermore, the socket structure includes a straight insertion section, the end of the plastic tube is inserted into the insertion section, and the insertion section is provided with a flared sealing groove.

[0012] Furthermore, the EPDM rubber strip includes an integrally formed annular portion and a truncated conical portion, wherein the outer diameter of the annular portion is not less than the maximum outer diameter of the truncated conical portion.

[0013] Furthermore, the maximum outer diameter of the truncated conical portion is smaller than the outer diameter of the annular portion, and there is a rounded transition at the connection point; the inner circumference of the opening of the metal tube is provided with a rounded corner.

[0014] Furthermore, the inner circumference of the EPDM rubber strip is provided with several arc-shaped protrusions.

[0015] Furthermore, the upper end of the inner circumference of the EPDM rubber strip is provided with a notch, and the bottom of the metal flange is provided with an annular boss, which is engaged with the notch.

[0016] Furthermore, the inner diameter of the metal flange is not less than the outer diameter of the plastic pipe, and the outer periphery of the metal flange and the flange edge is provided with a plurality of corresponding connecting lugs, which are connected by bolts.

[0017] Furthermore, the metal pipe is a cast iron pipe, the metal flange is a steel flange, and the plastic pipe is a UPVC pipe.

[0018] Furthermore, the lower end of the EPDM rubber strip is also provided with a hollow annular sealing ring.

[0019] Compared with the prior art, the beneficial effects of this utility model are: 1. This efficient connection structure between UPVC pipe and cast iron pipe combines the rigid fixing of the steel flange with the elastic sealing of the EPDM rubber strip through the setting of the EPDM rubber strip, the steel flange and bolts, etc., rather than simply relying on the rigid fit between the flange face and the ordinary rubber gasket, forming a "rigid and flexible" adaptable structure; it can solve the problem of interface loosening caused by the difference in thermal expansion and contraction between cast iron and UPVC pipe, and improve the deformation adaptability of the connection structure; moreover, it simplifies the connection process, reduces the dependence on professional welding and bonding processes, and improves the construction efficiency of old community renovation; 2. This efficient connection structure between UPVC pipe and cast iron pipe abandons the traditional split connection structure of "cast iron pipe welded flange, UPVC pipe glued flange, rubber clamp form", and adopts an integrated assembly design in which the steel flange is directly inserted into the UPVC pipe, eliminating the need for The welding and bonding process not only reduces construction difficulty and improves connection efficiency, but also allows for non-destructive disassembly of UPVC pipes in the later stages, facilitating the replacement of parts; 3. By improving the structure of the EPDM rubber strip, it can generate extrusion force on the plastic pipe, tightly wrapping the plastic pipe. At the same time, its upper end can also protrude a sealing groove, forming circumferential and axial seals with the metal flange and the flange edge, achieving embedded sealing rather than planar sealing; 4. When the arc-shaped protrusions are set on the inner circumference of the EPDM rubber strip, the surface contact during insertion can be changed to line contact, or even point contact, greatly reducing the contact area and friction between the plastic pipe and the EPDM, making insertion smoother. When the EPDM rubber strip is squeezed, these arc-shaped protrusions can deform, becoming flat and tightly fitting the outer circumference of the plastic pipe, forming a sealing structure that wraps the outer circumference of the plastic pipe. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a high-efficiency connection structure between a UPVC pipe and a cast iron pipe according to this utility model. Figure 2 This is a schematic diagram of the structure after the UPVC pipe and cast iron pipe of this utility model are connected. Figure 3This is a top view schematic diagram of an efficient connection structure between a UPVC pipe and a cast iron pipe according to the present invention; Figure 4 for Figure 3 Schematic diagram of the AA section structure; Figure 5 This is a schematic diagram of the structure of the EPDM rubber strip of this utility model; Figure 6 This is a schematic diagram of the installation of another type of EPDM rubber strip according to the present invention; Figure 7 This is a schematic diagram of the connection structure of another EPDM rubber strip of this utility model; Figure 8 A schematic diagram of the connection structure of the present invention, which has a raised EPDM rubber strip on the inner circumference (before being subjected to force); Figure 9 This is a schematic diagram of the connection structure of the EPDM rubber strip with protrusions on the inner circumference of the present invention (after stress). Figure 10 This is a schematic diagram of the addition of an annular sealing ring below the EPDM rubber strip in this utility model; In the diagram: 1. Metal pipe; 2. Plastic pipe; 3. Flange edge; 4. Metal flange; 5. EPDM rubber strip; 501. Circular part; 502. Frustum-shaped part; 6. Bolt; 7. Insertion section; 8. Sealing groove; 9. Rounded transition; 10. Rounded corner; 11. Notch; 12. Circular boss; 13. Arc-shaped protrusion; 14. Circular sealing ring. Detailed Implementation

[0021] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0022] In the description of this utility model, it should be noted that the terms "middle", "upper", "lower", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0023] Example 1: As Figures 1-4As shown, a high-efficiency connection structure for UPVC pipes and cast iron pipes is provided, including a metal pipe 1 and a plastic pipe 2 to be connected. The metal pipe 1 has a flange 3 on its outer periphery and a socket structure on its inner periphery. The socket structure has a sealing groove 8, and an EPDM rubber strip 5 is provided in the sealing groove 8. The axial dimension of the EPDM rubber strip 5 is greater than the axial depth of the sealing groove 8. The plastic pipe 2 is fitted with a metal flange 4 on its outer periphery. The plastic pipe 2 is inserted into the socket structure. The metal flange 4 and the flange 3 are fastened together by a number of bolts. The EPDM rubber strip 5 is squeezed to form a sealing structure between the plastic pipe 2 and the metal pipe 1, and a portion of the upper end of the EPDM rubber strip 5 is located between the flange 3 and the metal flange 4.

[0024] In this embodiment, the metal pipe 1 is a type A cast iron pipe, the metal flange 4 is a steel flange, and the plastic pipe 2 is a UPVC pipe.

[0025] This efficient connection structure between UPVC and cast iron pipes combines the rigid fixation of the steel flange with the elastic sealing of the EPDM rubber strip 5 through the installation of the EPDM rubber strip 5, the steel flange, and bolts, rather than simply relying on the rigid fit between the flange face and ordinary rubber gaskets, forming a "rigid-flexible" adaptable structure. It can solve the problem of loosening of the interface caused by the difference in thermal expansion and contraction between cast iron and UPVC pipes, and improve the deformation adaptability of the connection structure. Moreover, it simplifies the connection process, reduces the reliance on professional welding and bonding processes, and improves the construction efficiency of old residential area renovation.

[0026] This efficient connection structure between UPVC and cast iron pipes abandons the traditional split connection structure of "cast iron pipe welded flange, UPVC pipe glued flange, and rubber clamp". It adopts an integrated assembly design in which steel flanges are directly fitted into UPVC pipes, eliminating welding and bonding processes. This not only reduces construction difficulty and improves connection efficiency, but also allows for non-destructive disassembly of UPVC pipes in the later stages, facilitating the replacement of parts.

[0027] By improving the structure of the EPDM rubber strip 5, it can generate a squeezing force on the plastic tube 2 after being pressed by the metal flange 4 when installed in the sealing groove 8 of the socket structure, tightly wrapping the plastic tube 2. It can also deform to adapt to the structure of the sealing groove 8, and its upper end can protrude from the sealing groove 8, forming a circumferential and axial seal with the metal flange 4 and the flange edge 3. The aging-resistant and corrosion-resistant EPDM rubber strip 5 replaces the ordinary rubber gasket, and the strip can adapt to the socket structure of type A cast iron pipe, achieving an embedded seal rather than a planar seal.

[0028] Furthermore, the socket structure includes a straight insertion section 7, the end of the plastic tube 2 is inserted into the insertion section 7, and the insertion section 7 is provided with a flared sealing groove 8.

[0029] An insert connection is designed specifically for the socket characteristics of Type A cast iron pipes. By utilizing the pipe's own structural positioning, the reliance on additional positioning components can be reduced, and pipe connection can be completed directly through the insert connection.

[0030] Furthermore, in combination Figure 5 As shown, the EPDM rubber strip 5 includes an integrally formed annular portion 501 and a truncated conical portion 502, wherein the outer diameter of the annular portion 501 is not less than the maximum outer diameter of the truncated conical portion 502.

[0031] The inner wall of the sealing groove 8 is inclined, and the truncated cone-shaped part 502 can be engaged in the sealing groove 8 to form axial and circumferential forces, allowing this part to fit tightly with the plastic tube 2 to form a sealing structure; the upper annular part 501 can form a sealing structure between the metal flange 4, the flange edge 3 and the plastic tube 2.

[0032] Furthermore, the inner diameter of the metal flange 4 is not less than the outer diameter of the plastic pipe 2. The outer periphery of the metal flange 4 and the flange edge 3 is provided with three corresponding connecting ears, which are connected by bolts 6. The connecting ears can reduce the outer diameter of the flange while satisfying the connection requirements.

[0033] In some implementations, such as Figure 6 As shown, the maximum outer diameter of the truncated conical portion 502 is smaller than the outer diameter of the annular portion 501, and there is a rounded transition 9 at the connection. The inner circumference of the opening of the metal tube 1 is provided with a rounded corner 10. This design allows the EPDM rubber strip 5 to better withstand force and deformation, avoids stress concentration, and forms a good sealing structure. It also prevents the right angle or sharp corner of the opening from damaging the EPDM rubber strip and affecting its service life.

[0034] In some implementations, such as Figure 7 As shown, the upper end of the inner circumference of the EPDM rubber strip 5 is provided with a notch 11, and the bottom of the metal flange 4 is provided with an annular boss 12, which is engaged with the notch 11.

[0035] The notch 11 and the annular boss 12 are designed to provide circumferential positioning and also to form a stepped sealing structure after assembly, which helps to improve sealing performance and connection performance.

[0036] In some implementations, such as Figure 8 and Figure 9As shown, the inner circumference of the EPDM rubber strip 5 is provided with several arc-shaped protrusions 13.

[0037] Under normal circumstances, to ensure the subsequent sealing effect, the inner diameter of the EPDM rubber strip 5 is roughly the same as the outer diameter of the plastic tube 2 in its natural state, with little difference. Since the plastic tube 2 needs to pass through the EPDM rubber strip 5 when inserted into the socket structure, there will be friction between the plastic tube 2 and the EPDM rubber strip 5, which is not conducive to quick insertion. When the arc-shaped protrusions 13 are provided on the inner circumference of the EPDM rubber strip 5, the contact during insertion changes from surface contact to line contact, or even point contact, which can greatly reduce the contact area and friction between the plastic tube and the EPDM, making the insertion smoother. When the EPDM rubber strip 5 is squeezed, these arc-shaped protrusions 13 can deform and become flat, tightly fitting the outer circumference of the plastic tube 2 to form a sealing structure that wraps around the outer circumference of the plastic tube.

[0038] In some implementations, such as Figure 10 As shown, the lower end of the EPDM rubber strip 5 is also provided with a hollow annular sealing ring 14. Since the lower end of the EPDM rubber strip also has an end face, there will be some gaps at its lower end after assembly. The annular sealing ring 14 can fill these gaps and further improve the sealing effect. During installation, the annular sealing ring 14 can be placed into the sealing groove 8 first, and then the EPDM rubber strip 5 can be lowered in.

[0039] Example 2: An assembly method is provided for the efficient connection structure between UPVC pipe and cast iron pipe in Example 1.

[0040] Step 1: Check the appearance and dimensions of each component: The steel flange surface should be free of zinc layer peeling and deformation; bolt hole positions should be accurate; bolts should be free of thread damage and rust; EPDM rubber strips should be free of cracks and bubbles, and cross-sectional dimensions should meet design requirements; UPVC pipe ends should be flat, without dents or cracks; Type A cast iron pipe sockets (socket structure) should be undamaged, sealing grooves clean, and bolt holes unblocked. Lightly sand the outer wall of the UPVC pipe end (within a 50mm length) to remove surface oil and oxide layers, creating a mating surface and enhancing the fit with the steel flange. Step 2: Hold the steel flange with both hands, align its inner diameter with the end of the UPVC pipe, and slowly slide it onto the UPVC pipe until the steel flange is 25mm away from the end of the UPVC pipe; wipe the outer wall of the UPVC pipe after it is fitted onto the flange with a cotton cloth to ensure that there are no impurities left behind, so as to avoid affecting the subsequent sealing effect. Step 3: Install the EPDM rubber strip. Clean the sealing groove inside the A-type cast iron pipe with a cotton cloth to remove dust and oil. Gently place the EPDM rubber strip into the sealing groove, ensuring that the strip is completely attached to the groove wall without twisting or protrusion.

[0041] Step 4: Insert the UPVC pipe into the type A cast iron pipe. One person holds the A-type cast iron pipe to keep it fixed; the other person holds the end of the UPVC pipe with the steel flange with both hands, aligns the end of the UPVC pipe with the socket of the cast iron pipe, and slowly inserts it into the socket. During the insertion process, keep the pipe coaxial to avoid scratching the rubber strip. Continue inserting until a 5mm expansion gap is left between the end of the UPVC pipe and the bottom of the inserted section of the cast iron pipe. Make slight adjustments to ensure that the bolt holes of the steel flange are fully aligned with the bolt holes on the end face of the cast iron pipe. Step 5: Tightening bolts and adjusting connections Remove the bolts and pass them through the bolt holes of the steel flange and the cast iron pipe flange in sequence. Put a spring washer and a nut on the other end of the bolt and then tighten them. Step 6: Sealing performance test Close the main valve of the drainage system, connect a temporary pressure testing device to the other end of the UPVC pipe and inject clean water into the pipe to remove air from the pipe; Slowly increase the pressure to 0.2 MPa and maintain the pressure for 30 minutes. Observe whether the pressure gauge reading drops. At the same time, wipe the connection interface with a dry cotton cloth to check for any water leakage. If there is no pressure drop and no water leakage at the interface, the sealing performance is qualified. If there is a pressure drop or water leakage, the bolts need to be loosened, the EPDM rubber strip needs to be checked for displacement or damage, and after adjustment, it needs to be tightened again and pressure tested until it is qualified.

[0042] This embodiment is applied to the renovation project of the drainage pipes in the toilets of an old residential community. The original drainage system of the community used DN100 cast iron pipes. Due to the long service life, corrosion and scaling problems have appeared on the inner wall of the pipes, resulting in a decrease in drainage efficiency and leakage at some joints. It is necessary to replace the branch pipes in the toilets with DN100 UPVC pipes, and the underground pipes are A-type cast iron pipes. Therefore, it is necessary to achieve an efficient connection between DN100 UPVC pipes and A-type cast iron pipes to solve the defects of traditional connection methods in terms of thermal expansion and contraction adaptation, sealing durability, and construction efficiency.

[0043] Through the implementation of the above connection structure and method, the resistance to thermal expansion and contraction is significantly improved: through the synergistic mechanism of "rigid fixing + elastic sealing", the elastic deformation of the EPDM rubber strip can absorb the small displacement caused by temperature changes between the cast iron and the UPVC pipe, and completely solve the loosening problem caused by deformation differences in traditional structures.

[0044] Doubled sealing reliability and durability: EPDM rubber strips have a service life of over 10 years, which is 6-8 years longer than ordinary rubber gaskets.

[0045] Construction efficiency is improved by more than 50%: the flange welding and bonding curing process is eliminated, and the installation time of a single interface is shortened from the traditional 40-60 minutes to 15-20 minutes, which is especially suitable for the rapid construction needs of small spaces in old communities.

[0046] Enhanced connection stability and adaptability: The high strength of steel flanges avoids the deformation defects of UPVC flanges. Combined with the insertion positioning of type A cast iron pipe sockets, the coaxiality error of the connection can be controlled within 0.5mm, reducing the risk of stress concentration in the pipeline.

[0047] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-efficiency connection structure between UPVC pipe and cast iron pipe, comprising a metal pipe and a plastic pipe to be connected, characterized in that, The metal pipe has a flange on its outer periphery and a socket structure on its inner periphery. The socket structure contains a sealing groove, and an EPDM rubber strip is placed within the sealing groove. The axial dimension of the EPDM rubber strip is greater than the axial depth of the sealing groove. A metal flange is fitted around the outer periphery of the plastic pipe, which is inserted into the socket structure. The metal flange is fastened to the flange by several bolts. The EPDM rubber strip is compressed to form a sealing structure between the plastic pipe and the metal pipe, with the upper part of the EPDM rubber strip located between the flange and the metal flange.

2. The high-efficiency connection structure between UPVC pipe and cast iron pipe according to claim 1, characterized in that, The socket structure includes a straight insertion section, the end of the plastic tube is inserted into the insertion section, and the insertion section is provided with a flared sealing groove.

3. The high-efficiency connection structure between UPVC pipe and cast iron pipe according to claim 1, characterized in that, The EPDM rubber strip includes an integrally formed annular portion and a truncated conical portion, wherein the outer diameter of the annular portion is not less than the maximum outer diameter of the truncated conical portion.

4. The high-efficiency connection structure between UPVC pipe and cast iron pipe according to claim 3, characterized in that, The maximum outer diameter of the truncated conical portion is smaller than the outer diameter of the annular portion, and there is a rounded transition at the connection point. The inner circumference of the opening of the metal tube is rounded.

5. The high-efficiency connection structure between UPVC pipe and cast iron pipe according to claim 1, characterized in that, The inner circumference of the EPDM rubber strip is provided with several arc-shaped protrusions.

6. The high-efficiency connection structure between UPVC pipe and cast iron pipe according to claim 1, characterized in that, The upper end of the inner circumference of the EPDM rubber strip is provided with a notch, and the bottom of the metal flange is provided with an annular boss, which is engaged with the notch.

7. The high-efficiency connection structure between UPVC pipe and cast iron pipe according to claim 1, characterized in that, The inner diameter of the metal flange is not less than the outer diameter of the plastic pipe. The outer periphery of the metal flange and the flange edge is provided with a plurality of corresponding connecting lugs, which are connected by bolts.

8. The high-efficiency connection structure between UPVC pipe and cast iron pipe according to claim 1, characterized in that, The metal pipe is a cast iron pipe, the metal flange is a steel flange, and the plastic pipe is a UPVC pipe.

9. The high-efficiency connection structure between UPVC pipe and cast iron pipe according to claim 1, characterized in that, The lower end of the EPDM rubber strip is also provided with a hollow annular sealing ring.

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