Connecting pipe fitting for steel-plastic composite pipe
By using a special adhesive for double bonding between the steel-plastic composite pipe and the connecting fittings, and combining the design of metal and plastic layers, the problems of water leakage and high energy consumption in the connection of steel-plastic composite pipes are solved, realizing a low-cost and efficient connection method, and also having fireproof and heat insulation functions.
Patent Information
- Application Number
- CN202520623554.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-03
- Publication Date
- 2026-01-09
- Estimated Expiration
- 2035-04-03
AI Technical Summary
The existing connection methods for steel-plastic composite pipes and connecting fittings have the potential for water leakage, high energy consumption, and high cost. Furthermore, hot-melt or electrofusion connection methods are not economical.
The inner and outer walls of the socket of the connecting pipe body are double-bonded to the steel-plastic composite pipe with a special adhesive. The design of metal and plastic layers achieves a stable connection at room temperature.
It reduces construction costs and energy consumption, improves construction efficiency, prevents water leakage hazards, enhances the stability and safety of connections, and has fireproof and heat insulation functions.
Smart Images
Figure CN223782356U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of steel-plastic composite pipe connection technology, and specifically to a connecting pipe fitting for steel-plastic composite pipes. Background Technology
[0002] Steel-plastic composite pipe is a new type of pipe material with a plastic layer coated on the inside and outside of a metal pipe. It is widely used in water and gas circulation systems in urban residential buildings.
[0003] Most existing steel-plastic composite pipes, including the inner and outer plastic layers and connecting fittings, are injection molded from thermoplastic materials (PE, PP-R, PE-RT, etc.). When connecting steel-plastic composite pipes to fittings, the connection point between the pipe and fitting needs to be sealed to prevent water from seeping through and causing leakage in the pipeline system. However, sealing the pipe ends can sometimes result in leaks, posing a safety hazard. Furthermore, existing steel-plastic composite pipes are typically connected to fittings using hot-melt or electrofusion methods, which are energy-intensive and costly. Utility Model Content
[0004] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a connecting pipe fitting for steel-plastic composite pipes.
[0005] To achieve the above objectives, this utility model adopts the following technical solution:
[0006] A connecting fitting for steel-plastic composite pipes includes a connecting fitting body and a steel-plastic composite pipe. The connecting fitting body has an interface, and the interface is provided with a socket for receiving the end of the steel-plastic composite pipe. The socket extends circumferentially along the interface.
[0007] The socket has an inner wall and an outer wall along its radial direction, and the inner wall and / or the outer wall of the socket are connected by bonding to achieve the connection of the steel-plastic composite pipe.
[0008] Furthermore, the connecting pipe body includes a metal layer and a plastic layer, the metal layer is wrapped around the outside of the plastic layer, and the end of the plastic layer has an interface.
[0009] Furthermore, the thickness of the plastic layer on the outer side of the socket is greater than the thickness of the plastic layer on the inner side of the socket.
[0010] Furthermore, the plastic layer on the outer side of the socket protrudes outward along the axial direction of the socket from the plastic layer on the inner side of the socket.
[0011] Alternatively, the plastic layer inside the socket protrudes outward along the axial direction of the socket from the plastic layer outside the socket;
[0012] Alternatively, the end of the plastic layer on the inner side of the socket is flush with the end of the plastic layer on the outer side of the socket.
[0013] Furthermore, the bottom diameter of the inner wall of the socket is less than or equal to the inner diameter of the steel-plastic composite pipe, the end diameter of the inner wall of the socket is less than the inner diameter of the steel-plastic composite pipe, and the end diameter of the inner wall of the socket is less than the bottom diameter of the inner wall of the socket.
[0014] Furthermore, the bottom diameter of the outer wall of the socket is greater than or equal to the outer diameter of the steel-plastic composite pipe, the end diameter of the outer wall of the socket is greater than the outer diameter of the steel-plastic composite pipe, and the end diameter of the outer wall of the socket is greater than the bottom diameter of the inner wall of the socket.
[0015] Furthermore, the plastic layer is injection molded from CPVC, PVC, ABS, or PC materials.
[0016] Furthermore, a plurality of limiting portions are provided between the end of the metal layer and the plastic layer, distributed circumferentially along the interface;
[0017] Alternatively, the ends of the metal layer and the ends of the plastic layer can be planar.
[0018] Furthermore, the steel-plastic composite pipe includes an inner plastic layer, a steel pipe layer, and an outer plastic layer arranged sequentially from the inside to the outside.
[0019] Furthermore, the inner and outer plastic layers are injection molded from CPVC, PVC, ABS, or PC materials.
[0020] Compared with the prior art, this utility model provides a connecting pipe fitting for steel-plastic composite pipes, which has the following advantages:
[0021] 1. The socket of the connecting pipe fitting of this utility model is bonded to the steel-plastic composite pipe with a special adhesive, which has low construction cost, is quick and convenient, consumes little energy, greatly improves construction efficiency, and has huge economic and social benefits.
[0022] 2. The double bonding method of the socket of the connecting pipe fitting of this utility model with the inner and outer diameters of the steel-plastic composite pipe can effectively isolate the conveying medium. It is not necessary to seal the end face of the steel-plastic composite pipe and the bottom of the socket, thus preventing water from flowing between the end face of the steel-plastic composite pipe and the bottom of the socket and reducing safety hazards.
[0023] 3. The outer layer of the connecting pipe fitting of this utility model is protected by a metal layer, which can not only increase the working pressure of the connecting pipe fitting (the nominal pressure of the general connecting pipe fitting is below 2.0MPa), but also has fireproof and heat insulation functions. The pipeline system composed of it and steel-plastic composite pipe can be widely used in fire protection, water supply, high-rise drainage and other fields.
[0024] 4. The injection molding materials for the connecting pipe fittings and steel-plastic composite pipes of this utility model are CPVC, PVC, ABS or PC, etc., so that the steel-plastic composite pipes and connecting pipe fittings can be connected by double bonding at room temperature (thermoplastic materials (PE, PP-R, PE-RT, etc.) have low adhesion at room temperature and are easy to fall off. Therefore, thermoplastic pipe fittings are usually connected by hot melt or electrofusion connection methods). Attached Figure Description
[0025] Figure 1 This is a cross-sectional structural diagram of the connection between the pipe fitting body and the steel-plastic composite pipe of this utility model;
[0026] Figure 2 This is a cross-sectional structural schematic diagram of the first embodiment of the connecting pipe fitting body of this utility model;
[0027] Figure 3 This is a schematic cross-sectional view of the steel-plastic composite pipe of this utility model;
[0028] Figure 4 yes Figure 1 Enlarged structural diagram at point A;
[0029] Figure 5 This is a cross-sectional structural schematic diagram of the second embodiment of the connecting pipe body of this utility model;
[0030] Figure 6 This is a cross-sectional structural schematic diagram of the third embodiment of the connecting pipe body of this utility model;
[0031] Figure 7 This is a cross-sectional structural schematic diagram of the fourth embodiment of the connecting pipe body of this utility model;
[0032] Figure 8 This is a cross-sectional structural schematic diagram of the fifth embodiment of the connecting pipe body of this utility model.
[0033] The markings in the diagram are: 1. Connecting pipe body; 11. Metal layer; 12. Plastic layer; 13. Interface; 14. Socket; 15. Inner wall of socket; 16. Outer wall of socket; 17. Limiting part; 2. Steel-plastic composite pipe; 21. Inner plastic layer; 22. Steel pipe layer; 23. Outer plastic layer. Detailed Implementation
[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments:
[0035] All standard parts used in this utility model can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art, and the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here.
[0036] It should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", and "outer" 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.
[0037] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0038] In the description of this utility model, "multiple" means two or more, unless otherwise explicitly specified.
[0039] This utility model embodiment provides a connecting pipe fitting for steel-plastic composite pipes, see reference. Figure 1 and Figure 2 The system includes a connecting pipe body 1 and a steel-plastic composite pipe 2. The connecting pipe body 1 has an interface 13. The interface 13 is provided with a socket 14 for accommodating the end of the steel-plastic composite pipe 2. The socket 14 extends circumferentially along the interface 13. The socket 14 has an inner wall 15 and an outer wall 16 in its radial direction. The inner wall 15 and / or the outer wall 16 of the socket are connected by bonding to achieve the connection of the steel-plastic composite pipe 2.
[0040] Specifically, the connector body 1 of this utility model has two interfaces 13; the socket 14 is an annular groove; the connector body 1 of this utility model can be applied to, but is not limited to, straight connectors, as well as bend connectors, tee connectors, cross connectors, reducing connectors, flange connectors, and other steel-plastic conversion parts with wire inserts; in this embodiment, the inner and outer diameters of the steel-plastic composite pipe 2 are simultaneously double-bonded to the inner wall 15 and outer wall 16 of the socket using a special adhesive, preventing the conveying medium from contacting the end face of the connector and reducing safety hazards; in other embodiments, the inner wall 15 of the socket is bonded to achieve the connection of the steel-plastic composite pipe 2; in other embodiments, the outer wall 16 of the socket is bonded to achieve the connection of the steel-plastic composite pipe 2; the end of the steel-plastic composite pipe 2 is bonded between the inner wall 15 and outer wall 16 of the socket.
[0041] Reference Figure 1 and Figure 2 In this embodiment, when using it, apply a special adhesive to the inner wall 15 and the outer wall 16 of the socket, and then insert the steel-plastic composite tube 2 into the socket 14.
[0042] In actual use, depending on the pressure conditions, one or more sealing rings (not shown in the figure) can be installed between the inner wall 15 and outer wall 16 of the socket and the steel-plastic composite pipe 2, and between the end of the steel-plastic composite pipe 2 and the bottom of the socket 14 to implement a double-layer seal of adhesive and sealing rings. Alternatively, sealing rings may not be installed.
[0043] Reference Figure 1 and Figure 2 In this embodiment, the connecting pipe body 1 includes a metal layer 11 and a plastic layer 12. The metal layer 11 is wrapped around the plastic layer 12, and the end of the plastic layer 12 has an interface 13.
[0044] Specifically, there are two molding methods for the connecting pipe body 1 of this utility model. The first method is that the outer metal layer 11 can be integral as a cavity, and the inner plastic layer 12 is injected into the plastic layer 12 by injection molding. The second method is that the inner plastic layer 12 and the metal layer 11 are stamped into a shell, wrapped around the inner plastic layer 12, and the two are welded together.
[0045] Reference Figure 1 and Figure 2 In this embodiment, the thickness of the plastic layer 12 on the outer side of the socket 14 is greater than the thickness of the plastic layer 12 on the inner side of the socket 14.
[0046] Specifically, in order to make the inner diameter of the steel-plastic composite pipe 2 as close as possible to the inner diameter of the connecting pipe body 1, the thickness of the plastic layer 12 on the outside of the socket 14 is greater than the thickness of the plastic layer 12 on the inside of the socket 14, so as to minimize the difference between the inner diameter of the steel-plastic composite pipe 2 and the inner diameter of the connecting pipe body 1 and achieve a good material transmission effect.
[0047] Reference Figure 1 and Figure 2 In this embodiment, the plastic layer 12 on the outer side of the socket 14 protrudes outward along the axial direction of the socket 14 from the plastic layer 12 on the inner side of the socket 14; this results in a shorter bonding length between the steel-plastic composite pipe 2 and the inner wall 15 of the socket, and a longer bonding length between the steel-plastic composite pipe 2 and the outer wall 16 of the socket when the steel-plastic composite pipe 2 is installed with the connecting pipe body 1; in other embodiments, the steel-plastic composite pipe 2 may be bonded only to the inner wall 15 or the outer wall 16 of the socket.
[0048] Reference Figure 7 In the fourth embodiment, the plastic layer 12 on the inner side of the socket 14 protrudes outward along the axial direction of the socket 14 from the plastic layer 12 on the outer side of the socket 14; this results in a longer bond length between the steel-plastic composite pipe 2 and the inner wall 15 of the socket, and a shorter bond length between the steel-plastic composite pipe 2 and the outer wall 16 of the socket when the steel-plastic composite pipe 2 is installed with the connecting pipe body 1; in other embodiments, the steel-plastic composite pipe 2 may be bonded only to the inner wall 15 or the outer wall 16 of the socket.
[0049] Reference Figure 8 In the fifth embodiment, the end of the plastic layer 12 on the inner side of the socket 14 is flush with the end of the plastic layer 12 on the outer side of the socket 14; so that when the steel-plastic composite pipe 2 is installed with the connecting pipe body 1, the length of the steel-plastic composite pipe 2 bonded to the inner wall 15 of the socket and the length of the steel-plastic composite pipe 2 bonded to the outer wall 16 of the socket are the same; in other embodiments, the steel-plastic composite pipe 2 may be bonded only to the inner wall 15 or the outer wall 16 of the socket.
[0050] Specifically, the above three embodiments facilitate the rapid installation of the steel-plastic composite pipe 2 and the connecting pipe body 1, achieving a stable socketing effect.
[0051] Reference Figure 1 and Figure 2 In this embodiment, the bottom diameter of the inner wall 15 of the socket is less than or equal to the inner diameter of the steel-plastic composite pipe 2, the end diameter of the inner wall 15 of the socket is less than the inner diameter of the steel-plastic composite pipe 2, and the end diameter of the inner wall 15 of the socket is less than the bottom diameter of the inner wall 15 of the socket.
[0052] Specifically, since the bottom diameter of the inner wall 15 of the socket is less than or equal to the inner diameter of the steel-plastic composite pipe 2, the end diameter of the inner wall 15 of the socket is less than the inner diameter of the steel-plastic composite pipe 2, and the end diameter of the inner wall 15 of the socket is less than the bottom diameter of the inner wall 15 of the socket, when the steel-plastic composite pipe 2 is inserted into the socket 14, the air in the socket 14 can be expelled, making it easier for the steel-plastic composite pipe 2 to be inserted into the socket 14; the bottom diameter of the inner wall 15 of the socket can be 0 to 0.2 mm less than the inner diameter of the steel-plastic composite pipe 2, and the end diameter of the inner wall 15 of the socket can be 0.3 to 0.6 mm less than the inner diameter of the steel-plastic composite pipe 2.
[0053] Reference Figure 1 and Figure 2 In this embodiment, the bottom diameter of the outer wall 16 of the socket is greater than or equal to the outer diameter of the steel-plastic composite pipe 2, the end diameter of the outer wall 16 of the socket is greater than the outer diameter of the steel-plastic composite pipe 2, and the end diameter of the outer wall 16 of the socket is greater than the bottom diameter of the inner wall 15 of the socket.
[0054] Specifically, since the bottom diameter of the outer wall 16 of the socket is greater than or equal to the outer diameter of the steel-plastic composite pipe 2, the end diameter of the outer wall 16 of the socket is greater than the outer diameter of the steel-plastic composite pipe 2, and the end diameter of the outer wall 16 of the socket is greater than the bottom diameter of the inner wall 15 of the socket, when the steel-plastic composite pipe 2 is inserted into the socket 14, the air inside the socket 14 can be expelled, making it easier for the steel-plastic composite pipe 2 to be inserted into the socket 14; the bottom diameter of the outer wall 16 of the socket can be 0 to 0.2 mm greater than the outer diameter of the steel-plastic composite pipe 2, and the end diameter of the outer wall 16 of the socket can be 0.3 to 0.6 mm greater than the outer diameter of the steel-plastic composite pipe 2.
[0055] Reference Figure 1 and Figure 2 In this embodiment, the plastic layer 12 is injection molded from CPVC, PVC, ABS or PC material.
[0056] Specifically, the plastic layer 12 is injection molded from CPVC, PVC, ABS or PC material, which enables the connecting pipe body 1 to be better connected to the steel-plastic composite pipe 2 at room temperature using a double bonding method.
[0057] Reference Figure 1 , Figure 2 and Figures 4 to 6 In this embodiment, a plurality of limiting portions 17 are provided between the end of the metal layer 11 and the plastic layer 12, which are distributed circumferentially along the interface 13.
[0058] Specifically, refer to Figure 1 , Figure 2 and Figure 4The limiting part 17 can be a limiting recess. By setting the limiting recess, the metal layer 11 and the plastic layer 12 can be prevented from delaminating, the metal layer 11 and the plastic layer 12 can be prevented from rotating, and the metal layer 11 and the plastic layer 12 can be prevented from thermal expansion and contraction. The limiting recess can be evenly distributed along the circumference of the interface 13 or unevenly distributed. The limiting recess can also be set on the inner wall 15 of the socket and the outer wall 16 of the socket. The limiting recess can be set as an annular groove.
[0059] Reference Figure 1 , Figure 2 and Figure 4 In the first embodiment, limiting recesses are provided on both the inner and outer sides of the end of the metal layer 11 and the outer side of the end of the plastic layer 12; it can also be configured such that the outer side of the end of the metal layer 11 is a horizontal smooth surface, and limiting recesses are provided on both the inner side of the end of the metal layer 11 and the outer side of the end of the plastic layer 12.
[0060] Reference Figure 5 In the second embodiment, the ends of the metal layer 11 and the plastic layer 12 are planar structures; specifically, the inner and outer sides of the ends of the metal layer 11 and the outer sides of the ends of the plastic layer 12 can both be horizontal smooth surfaces.
[0061] Reference Figure 6 In the third embodiment, the limiting part 17 can be a limiting boss; by setting the limiting boss, the metal layer 11 and the plastic layer 12 can be prevented from delaminating, the metal layer 11 and the plastic layer 12 can be prevented from rotating, and the metal layer 11 and the plastic layer 12 can be prevented from thermal expansion and contraction; the limiting boss can be evenly distributed around the interface 13 or unevenly distributed; the limiting boss can be a ring-shaped protrusion; the inner and outer sides of the end of the metal layer 11 and the outer side of the end of the plastic layer 12 are both provided with limiting bosses; it can also be configured such that the outer side of the end of the metal layer 11 is a horizontal smooth surface, and the inner side of the end of the metal layer 11 and the outer side of the end of the plastic layer 12 are both provided with limiting bosses.
[0062] Reference Figure 1 and Figure 3 In this embodiment, the steel-plastic composite pipe 2 includes an inner plastic layer 21, a steel pipe layer 22, and an outer plastic layer 23 arranged sequentially from the inside to the outside.
[0063] Specifically, the steel-plastic composite pipe 2 adopts a three-layer main structure, namely an inner plastic layer 21 and an outer plastic layer 23 located in the inner and outer layers. A steel pipe layer 22 is set in the middle of the inner plastic layer 21 and the outer plastic layer 23. The steel pipe layer 22 has sufficient strength and rigidity and is generally made of steel pipes by argon arc butt welding. The steel pipe layer 22 is bonded to the inner plastic layer 21 and the outer plastic layer 23 on both sides with special adhesives. While ensuring its rigidity, the inner plastic layer 21 and the outer plastic layer 23 also have the effect of good appearance and durability.
[0064] Reference Figure 1 and Figure 3 In this embodiment, the inner plastic layer 21 and the outer plastic layer 23 are injection molded from CPVC, PVC, ABS or PC materials.
[0065] Specifically, by injection molding the inner plastic layer 21 and the outer plastic layer 23 from CPVC, PVC, ABS or PC materials, the steel-plastic composite pipe 2 can be better connected to the connecting pipe body 1 at room temperature using a double bonding method.
[0066] In summary, the socket 14 of the connecting pipe fitting of this utility model is bonded to the steel-plastic composite pipe 2 with a special adhesive, which has low construction cost, is quick and convenient, consumes little energy, greatly improves construction efficiency, and has huge economic and social benefits.
[0067] The connection of the connecting pipe fitting in this utility model, with the socket 14 and the inner and outer diameters of the steel-plastic composite pipe 2 being double-bonded, can effectively isolate the conveyed medium. It does not require sealing the end face of the steel-plastic composite pipe 2 and the bottom of the socket 13, thus preventing water from flowing between the end face of the steel-plastic composite pipe 2 and the bottom of the socket 13 and reducing safety hazards.
[0068] The outer layer of the connecting pipe fitting of this utility model is protected by a metal layer 11, which can not only increase the working pressure of the connecting pipe fitting (the nominal pressure of the connecting pipe fitting is generally below 2.0MPa), but also has fireproof and heat insulation functions. The pipeline system composed of it and steel-plastic composite pipe 2 can be widely used in fire protection, water supply, high-rise drainage and other fields.
[0069] The injection molding materials of the connecting pipe fittings and the steel-plastic composite pipe 2 of this utility model are CPVC, PVC, ABS or PC, etc., so that the steel-plastic composite pipe 2 and the connecting pipe fittings can be connected by double bonding at room temperature (thermoplastic materials (PE, PP-R, PE-RT, etc.) have low adhesion at room temperature and are easy to fall off. Therefore, thermoplastic pipe fittings are usually connected by hot melt or electrofusion connection methods).
[0070] The contents not described in detail in this specification are existing technologies known to those skilled in the art.
[0071] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit the scope of protection of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. Although this utility model has been described in detail with reference to the above embodiments, those skilled in the art can still combine, add, delete, or otherwise adjust the features of the various embodiments of this utility model according to the circumstances without conflict or creative effort, thereby obtaining different technical solutions that do not fundamentally depart from the concept of this utility model. These technical solutions are also within the scope of protection of this utility model.
Claims
1. A connecting fitting for steel-plastic composite pipes, comprising a connecting fitting body (1) and a steel-plastic composite pipe (2), characterized in that, The connecting pipe body (1) has an interface (13), and the interface (13) is provided with a socket (14) for accommodating the end of the steel-plastic composite pipe (2), and the socket (14) extends circumferentially along the interface (13); The socket (14) has an inner wall (15) and an outer wall (16) along its radial direction, and the inner wall (15) and / or the outer wall (16) are connected to the steel-plastic composite pipe (2) by bonding.
2. The connecting fitting for steel-plastic composite pipes according to claim 1, characterized in that, The connecting pipe body (1) includes a metal layer (11) and a plastic layer (12), the metal layer (11) is wrapped around the plastic layer (12), and the end of the plastic layer (12) has an interface (13).
3. The connecting fitting for steel-plastic composite pipes according to claim 2, characterized in that, The thickness of the plastic layer (12) on the outside of the socket (14) is greater than the thickness of the plastic layer (12) on the inside of the socket (14).
4. The connecting fitting for steel-plastic composite pipes according to claim 3, characterized in that, The plastic layer (12) on the outside of the socket (14) protrudes outward along the axial direction of the socket (14) from the plastic layer (12) on the inside of the socket (14); Alternatively, the plastic layer (12) inside the socket (14) protrudes outward along the axial direction of the socket (14) from the plastic layer (12) outside the socket (14); Alternatively, the end of the plastic layer (12) inside the socket (14) is flush with the end of the plastic layer (12) outside the socket (14).
5. The connecting fitting for steel-plastic composite pipes according to claim 1, characterized in that, The bottom diameter of the inner wall (15) of the socket is less than or equal to the inner diameter of the steel-plastic composite pipe (2), the end diameter of the inner wall (15) of the socket is less than the inner diameter of the steel-plastic composite pipe (2), and the end diameter of the inner wall (15) of the socket is less than the bottom diameter of the inner wall (15).
6. The connecting fitting for steel-plastic composite pipes according to claim 1, characterized in that, The bottom diameter of the outer wall (16) of the socket is greater than or equal to the outer diameter of the steel-plastic composite pipe (2), the end diameter of the outer wall (16) of the socket is greater than the outer diameter of the steel-plastic composite pipe (2), and the end diameter of the outer wall (16) of the socket is greater than the bottom diameter of the inner wall (15) of the socket.
7. The connecting fitting for steel-plastic composite pipes according to claim 2, characterized in that, The plastic layer (12) is injection molded from CPVC, PVC, ABS or PC materials.
8. The connecting fitting for steel-plastic composite pipes according to claim 2, characterized in that, A plurality of limiting portions (17) are provided between the end of the metal layer (11) and the plastic layer (12) and distributed circumferentially along the interface (13); Alternatively, the ends of the metal layer (11) and the plastic layer (12) can be planar structures.
9. The connecting fitting for steel-plastic composite pipes according to claim 1, characterized in that, The steel-plastic composite pipe (2) includes an inner plastic layer (21), a steel pipe layer (22), and an outer plastic layer (23) arranged sequentially from the inside to the outside.
10. The connecting fitting for steel-plastic composite pipes according to claim 9, characterized in that, The inner plastic layer (21) and the outer plastic layer (23) are injection molded from CPVC, PVC, ABS or PC materials.