Connecting piece and connecting method for plastic pipe and composite pipe

Abstract

The invention discloses a connecting piece for a plastic pipe and a composite pipe and a connecting method, and particularly relates to the technical field of pipeline connection.The connecting piece comprises an electric melting pipe fitting used for connecting a plurality of pipes to be connected a, a plurality of pipes to be connected b and a plurality of pipes to be connected c, and an inner pipe is fixed in the electric melting pipe fitting; electric heating wire assemblies used for heating are arranged in the two ends of the electric melting pipe fitting, after the electric heating wire assemblies are heated, the ends of the electric melting pipe fitting are welded to a pipe a to be connected, a pipe b to be connected and a pipe c to be connected together and then communicate with the inner pipe, and pipeline connection is achieved. By arranging the heating wire for welding the electric melting pipe fitting and the to-be-connected pipe, the heating wire can be welded after the to-be-connected pipe is inserted into the electric melting pipe fitting, so that the operation difficulty is reduced, the operation efficiency is improved, and the connection effect and the sealing performance of the pipeline joint are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline connection, and more specifically to a connector for a plastic pipe or a composite pipe and a connection method. Background Art

[0002] The traditional installation fittings and connection methods of composite pressure pipes mainly include compression fittings, which use mechanical fastening connection; flange fittings, which use pipe end expansion and flange fastening connection; double-sided hot-melt fittings, which use electric heating tools to heat the inner and outer plastic layers of the composite pipe and the installation joint surface of the fittings at the same time, and then quickly insert the pipe into the fittings for hot-melt connection; electromagnetic fusion type double hot-melt fittings, which are similar to double-sided hot-melt fittings. The connection method is to first insert the pipe into the fittings, use electromagnetic induction to heat the middle layer of pipe steel, and conduct heat to thermally fuse the inner and outer plastic layers of the pipe with the joint surface plastic of the fittings.

[0003] The installation fittings and connection methods of the above-mentioned composite pipes have many shortcomings: 1) Mechanical fastening connections and flange fastening connection fittings both use a method of strongly compressing the plastic at the pipe end and using a rubber sealing ring for sealing. The disadvantages are: the rubber sealing ring is prone to aging, and the plastic on the joint surface continues to deform and loosen, affecting the sealing performance.

[0004] 2) Double-sided hot-melt pipe fittings use plastic hot-melt connection between the inner and outer layers of the composite pipe and the joint surface of the fitting. The connection strength and sealing performance are good. However, the electric heating tool is used to heat the joint surface of the pipe and the fitting separately and then insert the fitting for welding. The pipe and the fitting must be heated to the molten state at the same time, which has high heating requirements. When the pipe is inserted into the fitting, the inner and outer molten layers of plastic may be peeled off, resulting in pipe blockage or insufficient welding strength, making the installation and connection operation difficult.

[0005] 3) The installation method of electromagnetic induction welding is to first insert the pipe into the socket of the pipe fitting, and then use a special electromagnetic induction heating tool to heat it, so that the middle steel pipe layer heats up and conducts it to the plastic layer and the joint surface of the pipe fitting, so that the pipe and the joint surface of the pipe fitting are fused into one; its disadvantage is that it has very high requirements on the matching accuracy of the pipe and the pipe fitting, and the dimensions of the plastic extrusion and injection molding processing are difficult to achieve or the dimensional accuracy is unstable, which affects the installation and matching. Secondly, electromagnetic induction steel pipe heats up, conducts and heats the plastic, and the temperature of the heated steel pipe is too high. The secondary heating of the composite pipe locally affects the composite bonding strength of the steel pipe and the plastic, especially when the installation matching gap is too large and the heating time is long, which has a greater impact on the connection strength of the pipe and the pipe fitting. Summary of the invention

[0006] In order to overcome the above-mentioned defects of the prior art, the present invention provides a connector for plastic pipes and composite pipes and a connection method. By arranging a heating wire for fusing the electric fusion pipe fitting and the pipe to be connected, the pipe to be connected can be welded after being inserted into the electric fusion pipe fitting, thereby reducing the difficulty of operation, improving the operation efficiency, ensuring the connection effect and the sealing of the pipeline connection, so as to solve the problems arising from the above-mentioned background technology.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a connector for plastic pipes and composite pipes, comprising an electric fusion pipe fitting for connecting multiple pipes a to be connected, pipes b to be connected, and pipes c to be connected, an inner pipe is fixed inside the electric fusion pipe fitting, and electric heating wire assemblies for heating are built into both ends of the electric fusion pipe fitting. After heating, the electric heating wire assembly fuses the end of the electric fusion pipe fitting to the pipe a to be connected, the pipe b to be connected, and the pipe c to be connected together, and then connects with the inner pipe to achieve pipeline connection.

[0008] In a preferred embodiment, the electric heating wire assembly includes a heating wire a and a heating wire b, wherein the heating wire b is arranged inside the heating wire a, and the heating wire a and the heating wire b are connected by a connecting wire, and the other end of the heating wire a and the other end of the heating wire b are both connected to an electric connector a, and one end of the two electric connectors a away from the heating wire a and the heating wire b is connected to an electric socket a for connecting to a power cord plug; It also includes an electric heating wire c, both ends of which are connected to power connectors b, and one end of the two power connectors b away from the electric heating wire c is connected to a power socket b for connecting to a power cord plug.

[0009] In a preferred embodiment, the electric fusion pipe comprises an equal-diameter transverse tube, the inner diameters of the two ends of the equal-diameter transverse tube are equal, the power socket a is arranged at a position close to the port on the outer wall of the equal-diameter transverse tube, and the heating wire a and the heating wire b are both arranged in the inner wall at the end of the equal-diameter transverse tube; It also includes a 45° elbow, the inner diameters of the two ends of the 45° elbow are equal, the power socket a is arranged on the outer wall of the 45° elbow near the port, and the heating wire a and the heating wire b are both arranged in the inner wall of the 45° elbow end; It also includes a 90° elbow, the inner diameters of the two ends of the 90° elbow are equal, the power socket a is arranged on the outer wall of the 90° elbow near the port, and the heating wire a and the heating wire b are both arranged in the inner wall of the 90° elbow end; It also includes a three-way pipe, the inner diameters of the three ports of the three-way pipe are equal, the power socket a is arranged on the outer wall of the three-way pipe near the port, and the heating wire a and the heating wire b are both arranged in the inner wall of the end of the three-way pipe; It also includes a reducing cross tube, the inner diameters of the two ports of the reducing cross tube are different, the power socket a is arranged on the outer wall of the small inner diameter port of the reducing cross tube, and an electric heating wire c for heating is arranged in the inner wall of the other port of the reducing cross tube, both ends of the electric heating wire c are connected with power connectors b, and the end of the power connector b away from the electric heating wire c is provided with a power socket b, and the power socket b is located on the outer wall of the large inner diameter port of the reducing cross tube.

[0010] In a preferred embodiment, the number of the power sockets a on the outer wall of the equal-diameter transverse pipe, the number of the power sockets a on the outer wall of the 45° elbow pipe, and the number of the power sockets a on the outer wall of the 90° elbow pipe are all set to two; There are three power sockets a on the outer wall of the variable diameter transverse tube.

[0011] In a preferred embodiment, the inner tube comprises an inner tube a, the outer wall shape of the inner tube a is consistent with the inner cavity shape of the equal-diameter transverse tube, and the inner tube a is fixed inside the equal-diameter transverse tube; It also includes an inner tube b, the outer wall shape of the inner tube b is consistent with the inner cavity shape of the 45° elbow, and the inner tube b is fixed inside the 45° elbow; It also includes an inner tube c, the outer wall shape of the inner tube c is consistent with the inner cavity shape of the 90° elbow, and the inner tube c is fixed inside the 90° elbow; It also includes an inner tube d, the outer wall shape of the inner tube d is consistent with the inner cavity shape of the tee, and the inner tube d is fixed inside the tee; It also includes an inner tube e, which is fixed in the inner cavity of the small inner diameter port of the variable diameter cross tube.

[0012] In a preferred embodiment, the inner walls at both ends of the equal-diameter transverse tube, the inner walls at both ends of the 45° elbow tube, the inner walls at both ends of the 90° elbow tube, the inner walls at the three ends of the tee tube, and the inner wall of the small inner diameter end of the variable-diameter transverse tube are all provided with pipe grooves for accommodating the pipe a to be connected or the pipe c to be connected.

[0013] In a preferred embodiment, the pipes a, b and c to be connected are plastic pipes or composite pipes, the outer diameter of the pipe b to be connected is larger than the outer diameter of the pipe a to be connected, and the outer diameter of one end of the pipe c to be connected inserted into the pipe groove is consistent with the outer diameter of the pipe groove after expansion treatment.

[0014] The present invention also provides a method for connecting plastic pipes and composite pipes using the above-mentioned connector, and the specific steps are as follows: S1. Select the equal-diameter horizontal pipe, 45° elbow, 90° elbow, tee pipe, and variable-diameter horizontal pipe from the electric fusion pipe fittings according to the type of pipe to be connected; S2, inserting the pipe a or the pipe b to be connected into the pipe groove of the port of the electric fusion pipe fitting, or inserting one end of the pipe c to be connected into the pipe groove of one of the ports of the electric fusion pipe fitting after expansion; S. Insert the power cord plug into the power socket a and the power connector b of the electric heating wire assembly to supply power to the heating wire a, the heating wire b and the electric heating wire c. Use the heating wire a and the heating wire b to heat the contact position between the electric fusion pipe fitting and the pipe a and the pipe c to be connected. Use the connecting wire to heat the contact position between the electric fusion pipe fitting and the pipe b to be connected, so that they are welded together to complete the connection.

[0015] Technical effects and advantages of the present invention: The present invention provides a heating wire for fusing the electric fusion pipe fitting and the pipe to be connected at the end of the electric fusion pipe fitting, so that the pipe to be connected can be welded after being inserted into the electric fusion pipe fitting. On the one hand, it can reduce the difficulty of operation and improve the operation efficiency. On the other hand, it can also ensure the alignment of the pipelines, ensure the connection effect and the sealing of the pipeline connection.

[0016] The present invention arranges double-layer distributed heating wires a and heating wires b to provide double-sided electric fusion between the connected pipe a, the connected pipe c and the electric fusion pipe fitting, and arranges a single-layer electric heating wire c to provide single-sided electric fusion between the connected pipe b and the electric fusion pipe fitting for welding, so as to increase the contact area and further ensure the connection strength.

[0017] The electric fusion pipe fittings of the present invention have various forms, can be applied to the connection between different pipelines, have a wide range of applications, and have high economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a schematic diagram of connecting two pipes a to be connected by an equal-diameter transverse pipe in Example 1; Figure 3 for Figure 2 Enlarged view of part A in the middle; Figure 4 This is a schematic diagram of a 45° elbow connecting two pipes a to be connected in Example 2; Figure 5 A schematic diagram of connecting two pipes a to be connected by a 90° elbow in Embodiment 3; Figure 6 This is a schematic diagram of the three pipes a to be connected in the fourth embodiment; Figure 7 This is a schematic diagram of the reduced diameter transverse pipe connecting the pipe a to be connected and the pipe b to be connected in the fifth embodiment; Figure 8 This is a schematic diagram of the equal-diameter transverse pipe connecting the pipe c to be connected and the pipe a to be connected in Example 6.

[0019] The accompanying drawings are marked as follows: Electric fusion pipe fittings; 11. Equal diameter horizontal pipe; 12. 45° elbow; 13. 90° elbow; 14. Tee pipe; 15. Variable diameter horizontal pipe; Heating wire assembly; 21, heating wire a; 22, heating wire b; 23, connecting wire; 24, power connector a; 25, power socket a; 26, heating wire c; 27, power connector b; 28, power socket b; Inner tube; 31, inner tube a; 32, inner tube b; 33, inner tube c; 34, inner tube d; 35, inner tube e; Pipe slot; Pipe a to be connected; Pipe b to be connected; Tube to be connected c. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Refer to the instruction manual Figure 1 The present invention provides a connector for plastic pipes and composite pipes, including an electric fusion pipe fitting 1 for connecting multiple pipes a5, b6 and c7 to be connected. The pipes a5, b6 and c7 to be connected are plastic pipes or composite pipes, and the outer diameter of the pipe b6 to be connected is larger than the outer diameter of the pipe a5 to be connected. An inner pipe 3 is fixed inside the electric fusion pipe fitting 1, and both ends of the electric fusion pipe fitting 1 are built with electric heating wire assemblies 2 for heating. Specifically, as shown in Figure 3, the electric heating wire assembly 2 includes a heating wire a21 and a heating wire b22. The heating wire b22 is arranged inside the heating wire a21. The heating wire a21 and the heating wire b22 are connected by a connecting wire 23. The other ends of the heating wire a21 and the other ends of the heating wire b22 are connected to an electric connector a24. The ends of the two electric connectors a24 away from the heating wires a21 and b22 are connected to an electric socket a25 for connecting to a power cord plug. Further, such as Figure 7As shown: the structure of the electric heating wire assembly 2 also includes an electric heating wire c26, both ends of the electric heating wire c26 are connected to an electric connector b27, and one end of the two electric connectors b27 away from the electric heating wire c26 is connected to an electric socket b28 for connecting to a power cord plug. When in use, by inserting the power cord plug into the power socket a25 or the power socket b28, the heating wire a21, the heating wire b22, and the electric heating wire c26 are powered on to make them heat up, so that the end of the electric fusion pipe fitting 1 can be respectively fused with the pipe to be connected a5, the pipe to be connected b6, and the pipe to be connected c7, so that the inner pipe 3 inside the electric fusion pipe fitting 1 can be connected with the pipe to be connected a5, the pipe to be connected b6, and the pipe to be connected c7, so as to achieve pipeline connection.

[0022] The present invention will be described below in conjunction with specific embodiments: like Figure 2 and Figure 3 As shown, the electric fusion pipe fitting 1 in this embodiment uses an equal-diameter transverse pipe 11, the inner diameters of both ends of the equal-diameter transverse pipe 11 are equal, and it is mainly used to connect two horizontally distributed pipelines with the same inner and outer diameters.

[0023] An inner tube a31 is fixed on the inner wall of the equal-diameter transverse tube 11, and the shape of the outer wall of the inner tube a31 is consistent with the shape of the inner cavity of the equal-diameter transverse tube 11. The heating wire a21 and the heating wire b22 are both arranged in the inner wall at the end of the equal-diameter transverse tube 11, and the power socket a25 is arranged on the outer wall of the equal-diameter transverse tube 11 near the port. There are two power sockets a25 and they are respectively located on the outer walls at both ends of the equal-diameter transverse tube 11, which are just used to supply power to the heating wires b22 and the heating wires a21 located at both ends of the equal-diameter transverse tube 11.

[0024] Tube grooves 4 are provided on the inner walls at both ends of the equal-diameter transverse tube 11. When in use, one end of the two tubes a5 to be connected must be inserted into the tube grooves 4 at both ends of the equal-diameter transverse tube 11 respectively. Since the heating wires b22 and a21 are respectively located in the inner and outer circles of the tube grooves 4, after the power cord plug is inserted into the power socket a25 on the outer wall of the equal-diameter transverse tube 11, the power cord is used to supply power to the heating wires a21 and b22 to heat and melt the contact position between the equal-diameter transverse tube 11 and the tube a5 to be connected. After the power is disconnected to stop heating, the equal-diameter transverse tube 11 and the two tubes a5 to be connected can be welded together after the molten position cools down. At this time, the inner tube a31 inside the equal-diameter transverse tube 11 is connected to the inner cavities of the two tubes a5 to be connected, and the pipeline connection is completed.

[0025] like Figure 4 As shown, the electric fusion pipe fitting 1 in this embodiment uses a 45° elbow 12, the inner diameters of both ends of the 45° elbow 12 are equal, and it is mainly used to connect two pipes with the same inner and outer diameters and an angle of 135°.

[0026] The heating wire a21 and the heating wire b22 are both arranged in the inner wall at the end of the 45° elbow 12, and the power socket a25 is arranged on the outer wall of the 45° elbow 12 close to the port, and there are two power sockets a25 in total, which are respectively located on the outer walls of the two ports of the 45° elbow 12, and are used to supply power to the heating wire a21 and the heating wire b22 installed at the two ends of the 45° elbow 12.

[0027] An inner tube b32 is fixed to the inner wall of the 45° elbow 12. The outer wall shape of the inner tube b32 is consistent with the inner cavity shape of the 45° elbow 12, and one end thereof is tilted upward by 45°. Similar to the first embodiment, pipe grooves 4 are also provided at both ends of the 45° elbow 12. When in use, the pipe a5 to be connected needs to be inserted into the pipe groove 4 first, and then the power cord plug is inserted into the power socket a25 to energize the heating wires a21 and b22 inside to make them heat up, and the contact parts of the 45° elbow 12 and the pipe a5 to be connected are welded, so that the two pipes a5 to be connected can be connected to the inner pipe b32 inside the 45° elbow 12, thereby realizing pipeline connection.

[0028] like Figure 5 As shown, the electric fusion pipe fitting 1 in this embodiment uses a 90° elbow 13, the inner diameters of both ends of the 90° elbow 13 are equal, and it is mainly used for two pipelines with the same inner and outer diameters and an angle of 90°.

[0029] Similar to the first embodiment, tube grooves 4 are provided at both ends of the 90° elbow 13, the heating wire a21 and the heating wire b22 are both arranged in the inner wall at the end of the 90° elbow 13, and the power socket a25 is arranged on the outer wall of the 90° elbow 13 near the port. There are two power sockets a25 on the outer wall of the 90° elbow 13, which are used to energize the heating wires a21 and b22 inside the two ends of the 90° elbow 13.

[0030] Different from the first embodiment, an inner tube c33 is installed inside the 90° elbow 13, the outer wall shape of the inner tube c33 is consistent with the inner cavity shape of the 90° elbow 13, and the angle between the two ends of the inner tube c33 is 90°.

[0031] When the present embodiment is in use, the two tubes a5 to be connected also need to be inserted into the two tube grooves 4 respectively, and then the power cord plug is inserted into the power socket a25 to energize the heating wires a21 and b22, so that they heat up and melt the contact position between the tube a5 to be connected and the 90° elbow 13, so that the 90° elbow 13 can be welded into one with the two tubes a5 to be connected, and the two tubes a5 to be connected are connected with the inner tube c33.

[0032] like Figure 6As shown, the electric fusion pipe fitting 1 in this embodiment uses a tee pipe 14, which has three ports, and each port has the same inner diameter, and can be used to connect three pipes with the same inner and outer diameters.

[0033] Similar to the first embodiment, tube grooves 4 are provided at the three ports of the three-way tube 14, the heating wires a21 and b22 are arranged in the inner wall at the end of the three-way tube 14, and three power sockets a25 are respectively arranged on the outer wall of the three-way tube 14 near the three ports, so as to supply power to the heating wires a21 and b22 after the power cord is connected.

[0034] Different from the embodiment, the outer wall shape of the inner tube d34 fixed inside the tee tube 14 is consistent with the inner cavity shape of the tee tube 14, and the inner tube d34 has three ports.

[0035] When this embodiment is in use, the three pipes a5 to be connected need to be inserted into the three pipe grooves 4 respectively, and then the power cord plug is inserted into the power socket a25 to energize the heating wires a21 and b22, so that they heat up and melt the contact position between the pipe a5 to be connected and the three-way pipe 14, so that the three-way pipe 14 can be welded to the pipe a5 to be connected into one, and the pipe a5 to be connected can be connected to the inner pipe d34 to realize the pipeline connection.

[0036] like Figure 7 As shown, the electric fusion pipe fitting 1 in this embodiment adopts a reducer transverse pipe 15, the inner diameters of the two ends of the reducer transverse pipe 15 are different, and the inner diameters of the two ports are not equal. It is mainly used to connect two pipes with different diameters to expand the scope of application.

[0037] The power socket a25 is arranged on the outer wall of the small inner diameter port of the reducing cross tube 15, and an electric heating wire c26 for heating is also fixed in the inner wall of another large inner diameter port of the reducing cross tube 15, and both ends of the electric heating wire c26 are connected to power connectors b27, and a power socket b28 is provided at the end of the power connector b27 away from the electric heating wire c26, and the power socket b28 is located on the outer wall of the large inner diameter port of the reducing cross tube 15.

[0038] An inner tube e35 is also fixed in the inner wall of the reducing cross tube 15. The inner tube e35 is fixed in the inner cavity of the small inner diameter port of the reducing cross tube 15, and a tube groove 4 is opened at one end of the small inner diameter of the reducing cross tube 15. When in use, the pipe a5 to be connected is directly inserted into the tube groove 4, and another pipe b6 to be connected with a large outer diameter is inserted into the port with a large inner diameter of the reducing cross tube 15. Then, the power cord plug is respectively inserted into the power socket a25 and the power connector b27, and power is supplied to the heating wire a21, the heating wire b22 and the electric heating wire c26 respectively, so that they heat the contact parts of the pipe a5 to be connected and the reducing cross tube 15, and the contact parts of the pipe b6 to be connected and the reducing cross tube 15, so that they are melted together, and the pipe a5 to be connected and the pipe b6 to be connected are connected with the help of the inner tube e35 to realize the pipeline connection.

[0039] like Figure 8 As shown, the present invention can also be used to connect pipes with a diameter smaller than the pipe groove 4, by expanding one end of the pipe c7 to be connected so that it can be inserted into the pipe groove 4, and then supplying power to the heating wire a21 and the heating wire b22 to make them heat up, and then the end of the pipe c7 to be connected inserted into the pipe groove 4 is welded together with the equal-diameter transverse pipe 11. The advantages of this connection method are that the pipe has a large diameter, small water resistance, large flow rate, and obvious economic benefits.

[0040] It is worth noting that the equal-diameter transverse pipe 11 in this embodiment can be replaced by the 45° elbow 12, 90° elbow 13, tee pipe 14 and reducing transverse pipe 15 in the above-mentioned embodiment to connect different pipelines and expand the scope of application of the present invention, which will not be further elaborated here.

[0041] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A connector for plastic pipes and composite pipes, characterized in that: The invention comprises an electric fusion pipe fitting (1) for connecting a plurality of pipes to be connected a (5), a pipe to be connected b (6), and a pipe to be connected c (7), wherein an inner pipe (3) is fixed inside the electric fusion pipe fitting (1), and both ends of the electric fusion pipe fitting (1) are built with electric heating wire assemblies (2) for heating. After being heated, the electric heating wire assemblies (2) fuse the ends of the electric fusion pipe fitting (1) to the pipes to be connected a (5), the pipes to be connected b (6), and the pipes to be connected c (7), respectively, and then connect the ends to the inner pipe (3), thereby realizing pipeline connection.

2. A connector for plastic pipes and composite pipes according to claim 1, characterized in that: The electric heating wire assembly (2) comprises a heating wire a (21) and a heating wire b (22), wherein the heating wire b (22) is arranged inside the heating wire a (21), and the heating wire a (21) and the heating wire b (22) are connected via a connecting wire (23), and the other end of the heating wire a (21) and the other end of the heating wire b (22) are both connected to an electric connector a (24), and one end of the two electric connectors a (24) away from the heating wire a (21) and the heating wire b (22) is connected to an electric socket a (25) for connecting to a power cord plug; It also includes an electric heating wire c (26), both ends of which are connected to power connectors b (27), and one end of the two power connectors b (27) away from the electric heating wire c (26) is connected to a power socket b (28) for connecting to a power cord plug.

3. A connector for plastic pipes and composite pipes according to claim 2, characterized in that: The electric fusion pipe fitting (1) comprises an equal-diameter transverse pipe (11), the inner diameters of both ends of the equal-diameter transverse pipe (11) being equal, the power supply socket a (25) being arranged on the outer wall of the equal-diameter transverse pipe (11) near a port, and the heating wire a (21) and the heating wire b (22) being arranged in the inner wall at the end of the equal-diameter transverse pipe (11); It also includes a 45° elbow (12), wherein the inner diameters of both ends of the 45° elbow (12) are equal, the power socket a (25) is arranged on the outer wall of the 45° elbow (12) near the port, and the heating wire a (21) and the heating wire b (22) are both arranged in the inner wall at the end of the 45° elbow (12); It also includes a 90° elbow (13), wherein the inner diameters of both ends of the 90° elbow (13) are equal, the power socket a (25) is arranged on the outer wall of the 90° elbow (13) near the port, and the heating wire a (21) and the heating wire b (22) are both arranged in the inner wall at the end of the 90° elbow (13); It also includes a three-way pipe (14), wherein the inner diameters of the three ports of the three-way pipe (14) are equal, the power socket a (25) is arranged on the outer wall of the three-way pipe (14) near the port, and the heating wire a (21) and the heating wire b (22) are both arranged in the inner wall at the end of the three-way pipe (14); It also comprises a variable diameter transverse tube (15), wherein the inner diameters of the two ports of the variable diameter transverse tube (15) are different, the power socket a (25) is arranged on the outer wall of the port with a smaller inner diameter of the variable diameter transverse tube (15), an electric heating wire c (26) for heating is arranged in the inner wall of the other port of the variable diameter transverse tube (15), both ends of the electric heating wire c (26) are connected to power connectors b (27), and a power socket b (28) is arranged at one end of the power connector b (27) away from the electric heating wire c (26), and the power socket b (28) is located on the outer wall of the port with a larger inner diameter of the variable diameter transverse tube (15).

4. A connector for plastic pipes and composite pipes according to claim 3, characterized in that: The number of the power sockets a (25) on the outer wall of the equal-diameter horizontal pipe (11), the number of the power sockets a (25) on the outer wall of the 45° elbow pipe (12), and the number of the power sockets a (25) on the outer wall of the 90° elbow pipe (13) are all set to two; The number of the power sockets a (25) on the outer wall of the variable diameter transverse tube (15) is three.

5. A connector for plastic pipes and composite pipes according to claim 3, characterized in that: The inner tube (3) comprises an inner tube a (31), the outer wall shape of the inner tube a (31) is consistent with the inner cavity shape of the equal-diameter transverse tube (11), and the inner tube a (31) is fixed inside the equal-diameter transverse tube (11); It also includes an inner tube b (32), the outer wall shape of the inner tube b (32) is consistent with the inner cavity shape of the 45° elbow (12), and the inner tube b (32) is fixed inside the 45° elbow (12); It also includes an inner tube c (33), the outer wall shape of the inner tube c (33) is consistent with the inner cavity shape of the 90° elbow (13), and the inner tube c (33) is fixed inside the 90° elbow (13); It also includes an inner tube d (34), the outer wall shape of the inner tube d (34) is consistent with the inner cavity shape of the tee tube (14), and the inner tube d (34) is fixed inside the tee tube (14); It also includes an inner tube e (35), which is fixed in the inner cavity of the small inner diameter port of the reducing cross tube (15).

6. A connector for plastic pipes and composite pipes according to claim 3, characterized in that: The inner walls at both ends of the equal-diameter transverse tube (11), the inner walls at both ends of the 45° elbow tube (12), the inner walls at both ends of the 90° elbow tube (13), the inner walls at three ends of the tee tube (14), and the inner wall of the small inner diameter end of the variable-diameter transverse tube (15) are all provided with pipe grooves (4) for accommodating the pipe a (5) or the pipe c (7) to be connected.

7. A connector for plastic pipes and composite pipes according to claim 1, characterized in that: The pipe to be connected a (5), the pipe to be connected b (6) and the pipe to be connected c (7) are plastic pipes or composite pipes. The outer diameter of the pipe to be connected b (6) is greater than the outer diameter of the pipe to be connected a (5). The outer diameter of one end of the pipe to be connected c (7) inserted into the pipe groove (4) is consistent with the outer diameter of the pipe groove (4) after expansion treatment.

8. The method for connecting the plastic pipe and composite pipe connector according to claims 1 to 7, characterized in that: The following steps are involved: S1. Select the equal-diameter horizontal pipe (11), 45° elbow (12), 90° elbow (13), tee (14), and variable-diameter horizontal pipe (15) in the electric fusion pipe fitting (1) according to the type of pipe to be connected; S2, inserting the pipe a (5) or the pipe b (6) to be connected into the pipe groove (4) of the port of the electric fusion pipe fitting (1), or inserting one end of the pipe c (7) to be connected into the pipe groove (4) of one of the ports of the electric fusion pipe fitting (1) after expanding the hole; S3. Insert the power cord plug into the power socket a (25) and the power connector b (27) of the electric heating wire assembly (2) to supply power to the heating wire a (21), the heating wire b (22) and the electric heating wire c (26). The heating wire a (21) and the heating wire b (22) are used to heat the contact position between the electric fusion pipe fitting (1) and the pipe to be connected a (5) and the pipe to be connected c (7). The connecting wire (23) is used to heat the contact position between the electric fusion pipe fitting (1) and the pipe to be connected b (6), so that the pipes are fused together to complete the connection.

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