Electric melting pipe fitting capable of preventing copper leakage and glue overflow

Abstract

The utility model relates to an electric melting pipe fitting preventing copper leakage and glue overflow, which comprises a pipe body, a binding post and an electric melting area part, the pipe body comprises a cold area and a limiting block, the cold area is used for preventing melt glue from overflowing, the limiting block is used for limiting a pipe to prevent the pipe from being excessively inserted, and the binding post comprises an inner terminal and an outer terminal. The electric melting area part comprises a stepped annular winding part and an annular winding part, the annular winding part is a part mainly generating welding in the electric melting welding process, the stepped annular winding part comprises a first winding groove and a second winding groove, and the annular winding part comprises an annular winding groove; the thickness between the heating wire and the surface of the inner wall of the pipe fitting is larger than the thickness between the heating wire of the annular winding groove in the annular winding part and the surface of the inner wall of the pipe fitting through the arrangement of the first winding groove and the second winding groove in the stepped annular winding part, and the effect of preventing copper leakage and glue overflow is achieved.

Description

Technical Field

[0001] The utility model relates to the field of plastic pipe welding, and particularly to an anti-leakage copper overflow-proof electrofusion fitting. Background Art

[0002] During the current laying process of plastic pipes, electrofusion fittings are required. The principle of the existing electrofusion fittings on the market is that heating wires are embedded in the inner wall of the socket part of the fitting. After the pipe is inserted into the fitting until the socket part, a constant voltage or current is output by the electrofusion welder to supply the heating wires, so that the pre-set heating wires in the fitting generate heat to heat the outer walls of the fitting and the pipe. The molten fitting and pipe are re-connected by molecular chains under a certain pressure. After reaching the set welding time, the fitting and the pipe enter the cooling stage. During the cooling process, the molecular chains in the middle of the fitting and the pipe are re-arranged and crystallized, and finally the fitting and the pipe are fused.

[0003] The comparative document discloses a double anti-leakage gas electrofusion fitting, which is composed of a terminal, a heating wire, a limiting structure and a sealing mechanism. The heating wire is arranged on the same horizontal plane at both ends of the inner wall of the pipe, so that the whole heating wire is in the flowing molten glue. During the fusion process, the heating wire near the fitting mouth will protrude out of the pipe mouth and expose the end face under the action of the insertion force. The exposed heating wire may have a dripping problem due to the gap between the heating wire in the middle of the spiral coil and the plastic, and at the same time, the terminal may overheat due to the short circuit between the first turn of the heating wire and the terminal during the fusion process, failing to achieve the due sealing effect of the electrofusion fitting.

[0004] In the above-mentioned existing electrofusion fitting electrofusion welding technology, there will be problems such as glue overflow and even copper leakage at the fitting mouth during engineering application. This is because the whole heating wire is in the viscoelastic plastic, and the viscoelastic plastic has high fluidity on the inner wall of the fitting. Under the action of the insertion force, the heating copper wire will pop out of the fusion zone with the flow of the overflowing glue, resulting in copper leakage. Especially for PPR electrofusion fittings, due to the good fluidity of PPR, when it reaches the molten state, it is more likely to have glue overflow and even copper leakage problems. Summary of the Utility Model

[0005] The purpose of the utility model is to overcome the technical problem that the heating wire in the existing electrofusion fitting is likely to protrude out of the pipe mouth and expose the pipe mouth end face during fusion, and provide an electrofusion fitting that can prevent copper leakage. This electrofusion fitting can block the outward movement of the heating wire and achieve the technical effect of preventing copper leakage.

[0006] To achieve the above purpose, the technical scheme adopted by the utility model is as follows:

[0007] A leak-proof and copper-overflow-proof electrofusion pipe fitting, comprising a pipe body, terminal posts, an electrofusion melting zone part, and heating wires. The terminal posts are installed at both ends of the pipe body; the electrofusion melting zone part is located on the inner wall of the pipe body; the terminal posts include an inner connection end close to the inner wall of the pipe body and an outer connection end extending out of the outer wall of the pipe body; the heating wires are connected to the inner connection ends of the terminal posts, and the heating wires are installed on the electrofusion melting zone part. It is characterized in that the electrofusion melting zone part includes a stepped annular winding part; the stepped annular winding part is located on one side of the inner wall of the pipe body close to the terminal posts, and the step heights in the axial direction towards the center of the pipe fitting decrease in sequence.

[0008] Wherein, a glue coating layer the same as the pipe fitting material is coated outside the heating wires to prevent the heating wire windings from contacting and short-circuiting; through holes for installing the heating wires are opened at the inner connection ends of the terminal posts; shoulders are provided at the outer connection ends and are buried in the counterbore holes on the outer wall of the pipe body. The diameter of the inner connection end is the same as that of the shoulder, and the diameter of the shaft section between the shoulder and the inner connection end is smaller than the diameters of the shoulder and the inner connection end, so as to realize the fixation of the terminal posts in the radial direction of the pipe body.

[0009] When the above technical solution is used, electricity is applied to the outer connection ends of the terminal posts outside, and the heating wires in the electrofusion melting zone part start to heat and melt the electrofusion melting zone part. After reaching a certain temperature and pressure, the outer wall of the pipe material and the inner wall of the pipe fitting are fused together. At this time, the heating wires in the stepped grooves of the stepped annular winding part cannot form a large part of the molten glue around the heating wires to converge with the glue in the melting zone where the annular winding part is located, forming a section of transition cold zone. The heating wires and the unfused glue remain stationary, and the glue in the fixed melting zone cannot move out of the pipe orifice. After cooling for a period of time, the pipe material and the pipe fitting are completely fused.

[0010] Preferably, the stepped annular winding part has at least two levels of steps, and stepped annular winding grooves are provided on each level of step; the heating wires are wound on the stepped annular winding grooves. The stepped annular winding part is used to block the heating wires from extending out of the end face of the pipe fitting during electrofusion welding. When the number of steps is too small, the number of blocking coils is too small and the blocking effect is too poor. Since the stepped annular winding part needs to open winding grooves, its width and height are fixed. When the number of steps is too large, the plane of the heating wires rises, and the thickness between the heating wires and the outer wall of the pipe fitting becomes smaller, making it easy to melt through the outer wall of the pipe fitting. Therefore, the number of steps should be set to at least two levels.

[0011] Preferably, the electric fusion zone also includes an annular winding portion, which is used to expand the welding area of the electric fusion zone and enhance the welding effect; the annular winding portion is arranged on the side of the step with the lowest height of the stepped annular winding portion, and the annular winding portion includes a plurality of annular winding grooves axially arranged on the same layer; the heating wire is wound out of the stepped annular winding groove and then wound into the annular winding groove; the thickness between the stepped annular winding groove and the inner wall of the pipe is greater than the thickness between the annular winding groove and the inner wall of the pipe. During electric fusion welding, the thickness between the stepped annular winding groove and the inner wall of the pipe is large, the temperature rises slowly, the temperature is low, and the surrounding plastic has a high hardness, thereby preventing the heating wire from being carried out of the outside of the pipe by the flowing molten glue to cause copper leakage.

[0012] Preferably, the tube body area below the inner terminal of the terminal post is a cold zone, and the temperature of the cold zone during welding is lower than that of the electric fusion zone, which is used to block the flow of molten glue in the electric fusion zone and prevent the molten glue from overflowing from the pipe mouth.

[0013] Preferably, the tube body also includes a column sleeve located on the outer wall of the tube body for protecting the external terminal, the top of the column sleeve is higher than the top of the external terminal to better protect the terminal; the inner wall of the column sleeve is preset to a sufficient distance from the surface of the external terminal to facilitate power connection operation.

[0014] Preferably, the tube body further comprises a limiting block at the center inner wall of the tube body for limiting the inserted tube.

[0015] Preferably, a preset distance is provided between the limiting block and the annular winding portion to ensure that the pipe has a sufficient insertion depth when being inserted into the electric fusion pipe fitting.

[0016] Preferably, the limit block is a rectangular block. In addition, there is another setting in which a circular block is arranged around the circumference of the pipe at the center. The rectangular block is smaller in size than the latter and has a lower manufacturing cost while achieving the same effect.

[0017] Preferably, the tube body also includes flared portions at both ends, the inner diameter of the flared portions being larger than the inner diameter of the electric fusion zone, and the inner wall of the tube at the flared portion being an inclined surface inclined toward the axis of the tube, and the inner wall diameter gradually shrinks from the end face of the tube mouth toward the center of the tube to facilitate the insertion of the tube.

[0018] Specifically, a connection slope inclined toward the outer wall of the pipe fitting can be provided at the connection between the flared portion and the electric fusion zone. The slope and the outer wall of the pipe form a wedge-shaped space to accommodate overflowing molten glue to prevent the molten glue from accumulating and squeezing to generate stress. At the same time, the molten glue can further seal the pipe fitting and the pipe after cooling and solidifying.

[0019] Preferably, the stepped annular winding portion further includes an annular wall located on the side close to the terminal for separating the terminal from the stepped annular winding groove; the two steps of the stepped annular winding portion and the annular wall axially position the heating wire wound around the stepped annular winding groove. During the production of the pipe fitting, it can prevent the injection pressure from pushing the flowing high-temperature plastic and thus driving the heating wire to deviate from its set position; during the use process of pipe fitting fusion, it can also prevent the heating wire from contacting the terminal, resulting in short circuit and overheating.

[0020] Compared with the prior art, the beneficial effects of the present utility model are as follows: The pipe first removes the oxide layer at the welding part and then inserts it into the electrofusion pipe fitting. Then, the external connection end of the terminal is connected to electricity, and the heating wire is energized to start heating and melts the surrounding plastic after a period of time. The outer wall of the pipe and the inner wall of the pipe fitting are fused together. The stepped annular winding portion fixes the heating wire on its steps, preventing the overall leakage of the heating wire from the pipe fitting as it expands and flows with the high-temperature plastic. At the same time, the cold zone blocks the molten glue from overflowing from the pipe fitting opening, ultimately achieving the technical effects of preventing glue overflow and preventing copper leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of an electrofusion pipe fitting for preventing copper leakage and glue overflow of the present utility model;

[0022] Figure 2 It is a schematic structural diagram of an electrofusion pipe fitting for preventing copper leakage and glue overflow of the present utility model;

[0023] Figure 3 It is a schematic structural diagram of the electrofusion melting zone portion of an electrofusion pipe fitting for preventing copper leakage and glue overflow of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following will illustrate the embodiments of the present utility model with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification. The present utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present utility model. It should be understood that the preferred embodiments are only for illustrating the present utility model, rather than for limiting the protection scope of the present utility model.

[0025] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present utility model in a schematic manner. Therefore, only the components related to the present utility model are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components during actual implementation. The type, quantity, and ratio of each component during actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0026] Embodiment 1

[0027] As Figure 1 - Figure 2 shown in Embodiment 1 of a leak-proof and copper-overflow-proof electrofusion pipe fitting, which includes a pipe body 1, a terminal 2, an electrofusion melting zone 3, and a heating wire 4. The terminal 2 is installed at both ends of the pipe body 1; the electrofusion melting zone 3 is located on the inner wall of the pipe body 1; the terminal 2 includes an inner terminal 202 close to the inner wall of the pipe body 1 and an outer terminal 201 extending out of the outer wall of the pipe body 1; the heating wire 4 is connected to the inner terminal 202 of the terminal 2, and the heating wire 4 is installed on the electrofusion melting zone 3. The electrofusion melting zone 3 includes a stepped annular winding part 301; the stepped annular winding part 301 is located on one side of the inner wall of the pipe body 1 close to the terminal 2 and the step heights in the axial direction towards the center of the pipe fitting decrease in sequence.

[0028] Among them, a layer of encapsulation layer made of the same material as the pipe fitting is covered outside the heating wire 4 to prevent the winding of the heating wire 4 from contacting and short-circuiting; a through hole for installing the heating wire 4 is opened in the inner terminal 202 of the terminal 2; the outer terminal 201 is provided with a shoulder buried in the counterbore on the outer wall of the pipe body 1, and the diameter of the inner terminal 202 is the same as that of the shoulder. The diameter of the shaft section between the shoulder and the inner terminal 202 is smaller than the diameters of the shoulder and the inner terminal 202, so as to realize the fixation of the terminal 2 in the radial direction of the pipe body 1.

[0029] Specifically, the cross-section of the terminal 2 is circular. In addition, it can also be rectangular. When the diameter of the outer terminal 201 is 4 mm, the diameters of the shoulder and the inner terminal 202 should be 6 mm, and the diameter of the shaft section between the shoulder and the inner terminal 202 should be 3 mm.

[0030] Furthermore, the stepped annular winding part 301 has at least two levels of steps, and a stepped annular winding groove 3011 is arranged on each level of step; the heating wire 4 is wound on the stepped annular winding groove 3011. The stepped annular winding part is used to block the heating wire 4 from extending out of the end face of the pipe fitting during electrofusion welding. When the number of steps is too small, the number of blocking coils is too small and the blocking effect is too poor. And since the stepped annular winding part needs to open winding grooves, its width and height are fixed. When the number of steps is too large, the plane of the heating wire 4 rises, and the thickness between the heating wire 4 and the outer wall of the pipe fitting becomes smaller, making it easy to melt through the outer wall of the pipe fitting. Therefore, the number of steps should be set to two levels.

[0031] Specifically, to prevent the heating wire 4 wound on the stepped annular winding groove 3011 from melting through the stepped annular winding part 301 and making itself unable to be fixed, the radial thickness of each level of step should be at least one-fourth of the wall thickness of the pipe body 1. For example, for a pipe fitting with DN90, when the wall thickness of the pipe body 1 is 5 mm, the step thickness should be between 1.25 mm and 1.5 mm.

[0032] Further, the electrofusion melting zone portion 3 further includes an annular winding portion 302; the annular winding portion 302 is provided on the side of the step with the lowest height of the stepped annular winding portion 301; the annular winding portion 302 includes a plurality of annular winding grooves 3021 arranged axially on the same layer; the heating wire 4 winds out of the stepped annular winding groove 3011 and then winds into the annular winding groove 3021; the thickness between the stepped annular winding groove 3011 and the inner wall of the pipe fitting is greater than the thickness between the annular winding groove 3021 and the inner wall of the pipe fitting. During electrofusion welding, the thickness between the stepped annular winding groove 3011 and the inner wall of the pipe fitting is large, the temperature rise is slow, the temperature is low, and the surrounding plastic has high hardness, thereby preventing the heating wire 4 from being carried out of the pipe fitting by the flowing molten tape and causing copper leakage.

[0033] Specifically, the radial thickness of the annular winding portion 302 is the same as the thickness of the step of the stepped annular winding portion 301, and the distance between the grooves is between 3 mm and 4 mm. When the distance between the plane at one end where the annular winding portion 302 is connected to the stepped annular winding portion 301 and the center of the pipe fitting is between 45 mm and 50 mm, the annular winding portion 302 should be provided with ten annular winding grooves 3021.

[0034] Further, the region of the pipe body 1 below the inner connection end 202 of the terminal 2 is a cold zone 101. The temperature of the cold zone 101 during fusion welding is lower than that of the electrofusion melting zone portion 3, and is used to block the flow of the molten glue in the electrofusion melting zone portion 3 and prevent the molten glue from overflowing from the pipe fitting opening.

[0035] Beneficial effects of this embodiment: During the operation of this embodiment, the pipe material first removes the oxide layer at the welding part and then inserts it into the electrofusion pipe fitting. The outer connection end 201 of the terminal 2 is connected to electricity, and the heating wire 4 is energized to generate heat and melt the surrounding plastic after a period of time. The outer wall of the pipe material is fused with the inner wall of the pipe fitting. The stepped annular winding portion 301 fixes the heating wire on its step, preventing the heating wire 4 from leaking out of the pipe fitting as a whole due to the expansion and flow of the high-temperature plastic. At the same time, the cold zone 101 blocks the molten glue from overflowing from the pipe fitting opening, and finally achieves the technical effects of preventing glue overflow and copper leakage.

[0036] Embodiment 2

[0037] As Figure 1 - Figure 2 shown in an embodiment 2 of an electrofusion pipe fitting for preventing copper leakage and glue overflow, which includes a pipe body 1, terminals 2, an electrofusion melting zone portion 3, and a heating wire 4. The terminals 2 are installed at both ends of the pipe body 1; the electrofusion melting zone portion 3 is located on the inner wall of the pipe body 1; the terminals 2 include an inner connection end 202 close to the inner wall of the pipe body 1 and an outer connection end 201 extending out of the outer wall of the pipe body 1; the heating wire 4 is connected to the inner connection end 202 of the terminal 2, and the heating wire 4 is installed on the electrofusion melting zone portion 3. It is characterized in that the electrofusion melting zone portion 3 includes a stepped annular winding portion 301; the stepped annular winding portion 301 is located on the side of the inner wall of the pipe body 1 close to the terminal 2 and the step heights in the axial direction towards the center of the pipe fitting decrease in sequence.

[0038] Among them, a layer of rubber coating layer made of the same material as the pipe fitting is covered outside the heating wire 4 to prevent the windings of the heating wire 4 from contacting and short - circuiting; a through - hole for installing the heating wire 4 is opened at the inner wiring end 202 of the terminal 2; the outer wiring end 201 is provided with a shoulder buried in the counterbore on the outer wall of the pipe body 1, and the diameter of the inner wiring end 202 is the same as that of the shoulder. The diameter of the shaft section between the shoulder and the inner wiring end 202 is smaller than the diameters of the shoulder and the inner wiring end 202, realizing the fixation of the terminal 2 in the radial direction of the pipe body 1.

[0039] Furthermore, the pipe body 1 further includes a limiting block 102 at the inner wall of the center of the pipe body 1 for limiting the inserted pipe material.

[0040] Furthermore, a preset distance is set between the limiting block 102 and the annular winding part 302 to prevent the limiting block 102 from being melted and unable to limit the inserted pipe material. The preset distance refers to the distance between the end face of the annular winding part close to the limiting block 102 and the end face of the limiting block 102 close to the annular winding part 302. When the preset distance is too small, the limiting block 102 limits the pipe material prematurely, and the insertion depth of the pipe material is insufficient. When the preset distance is too large, the number of turns of the planar winding groove in the electro - fusion melting zone part 3 is too small, and the area of the melting and welding area is too small, resulting in a poor welding effect.

[0041] Specifically, for a pipe fitting with a DN90 specification, the preset distance between the end face of the annular winding part 302 close to the limiting block 102 and the end face of the limiting block 102 close to the annular winding part 302 is 10 mm to 20 mm. For a pipe fitting with a DN315 specification, this preset distance is increased to 30 mm to 50 mm.

[0042] Furthermore, the limiting block 102 is a cuboid. In addition, there is another setting, which is a circular ring stop block that winds around the circumference of the pipe fitting at the center. The cuboid stop block has a smaller volume compared to the latter, and the manufacturing cost is lower under the premise of achieving the same effect.

[0043] The beneficial effects of this embodiment compared with Embodiment 1: By setting the cuboid limiting block 102, the pipe material is limited during socket - and - spigot connection, preventing the welding length of the pipe materials entering from both ends from being different and reducing the welding effect. At the same time, it can also prevent the pipe materials at both ends from squeezing each other to generate too much stress and pushing the molten glue to bring out the heating wire 4 from the pipe fitting port.

[0044] Embodiment 3

[0045] As Figure 1 - Figure 3An embodiment 3 of a leak-proof copper-overflow electric fusion pipe fitting shown in FIG. 1 includes a pipe body 1, a terminal 2, an electric fusion zone 3, and a heating wire 4. The terminal 2 is installed on both ends of the pipe body 1; the electric fusion zone 3 is located on the inner wall of the pipe body 1; the terminal 2 includes an inner terminal 202 close to the inner wall of the pipe body 1 and an outer terminal 201 extending out of the outer wall of the pipe body 1; the heating wire 4 is connected to the inner terminal 202 of the terminal 2, and the heating wire 4 is installed on the electric fusion zone 3, and is characterized in that the electric fusion zone 3 includes a stepped annular winding portion 301; the stepped annular winding portion 301 is located on the side of the inner wall of the pipe body 1 close to the terminal 2 and the step height decreases successively in the axial direction toward the center of the pipe fitting.

[0046] Among them, the heating wire 4 is covered with a rubber layer of the same material as the pipe fitting to prevent the heating wire 4 winding from contacting and short-circuiting; the inner terminal 202 of the terminal 2 is provided with a through hole for installing the heating wire 4; the outer terminal 201 is provided with a shoulder buried in the countersunk hole on the outer wall of the tube body 1, the diameter of the inner terminal 202 is the same as the diameter of the shoulder, and the diameter of the shaft section between the shoulder and the inner terminal 202 is smaller than the diameter of the shoulder and the inner terminal 202, thereby realizing the fixation of the terminal 2 in the radial direction of the tube body 1.

[0047] Furthermore, the stepped annular winding portion 301 has at least two steps, and a stepped annular winding groove 3011 is provided on each step; the heating wire 4 is wound on the stepped annular winding groove 3011, and the stepped annular winding portion 301 is used to prevent the heating wire 4 from extending out of the end face of the pipe during electric fusion welding. When the number of steps is too small, the blocked coils are too small and the blocking effect is too poor. Since the steps need to open winding grooves, their width and height are fixed. When the number of steps is too many, the plane of the heating wire 4 rises, and the thickness between the heating wire 4 and the outer wall of the pipe becomes smaller, making it easy to melt through the outer wall of the pipe. Therefore, the steps should be set to two levels.

[0048] Furthermore, the stepped annular winding portion 301 also includes an annular wall 3012 located on the side close to the terminal 2 for separating the terminal 2 from the stepped annular winding groove 3011; the two steps of the stepped annular winding portion 301 and the annular wall 3012 axially position the heating wire 4 wound on the stepped annular winding groove 3011. During the production of pipe fittings, the injection molding pressure can be prevented from pushing the flowing high-temperature plastic and causing the heating wire 4 to deviate from its set position. During the use of pipe welding, the heating wire 4 can also be prevented from contacting the terminal 2 to cause short circuit and overheating.

[0049] Specifically, the axial width of the annular wall 3012 should be set between 4 mm and 6 mm. The annular wall 3012 of this thickness can separate the terminal 2 from the stepped annular winding groove 3011 to prevent the terminal 2 and the heating wire 4 from short-circuiting and overheating, and can also prevent the heating wire 4 from melting through it.

[0050] The remaining technical features and working principles of this embodiment are the same as those of Embodiment 1 or Embodiment 2.

[0051] The above embodiments are only preferred embodiments given to fully illustrate the present utility model, and the protection scope of the present utility model is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present utility model are all within the protection scope of the present utility model.

Claims

1. A leak-proof and copper-overflow-proof electric fusion pipe fitting, comprising a pipe body (1), a terminal (2), an electric fusion melting zone part (3), and a heating wire (4). The terminal (2) is installed at both ends of the pipe body (1); the electric fusion melting zone part (3) is located on the inner wall of the pipe body (1); the terminal (2) includes an inner connection end (202) close to the inner wall of the pipe body (1) and an outer connection end (201) extending out of the outer wall of the pipe body (1); the heating wire (4) is connected to the inner connection end (202) of the terminal (2), and the heating wire (4) is installed on the electric fusion melting zone part (3), characterized in that, The electrofusion melting zone part (3) includes a stepped annular winding part (301); the stepped annular winding part (301) is located on one side of the inner wall of the pipe body (1) close to the terminal (2), and the step heights in the axial direction towards the center of the pipe fitting decrease in sequence.

2. The leak-proof and copper-overflow-proof electrofusion pipe fitting according to claim 1, characterized in that, The stepped annular winding part (301) has at least two levels of steps, and stepped annular winding grooves (3011) are arranged on each level of step; the heating wire (4) is wound on the stepped annular winding grooves (3011).

3. The leak-proof and copper-overflow-proof electrofusion pipe fitting according to claim 2, wherein, The electrofusion melting zone part (3) further includes an annular winding part (302); the annular winding part (302) is arranged on one side of the step with the lowest height of the stepped annular winding part (301); the annular winding part (302) includes a plurality of annular winding grooves (3021) arranged axially on the same layer; after the heating wire (4) winds out of the stepped annular winding grooves (3011), it winds into the annular winding grooves (3021); the thickness between the stepped annular winding grooves (3011) and the inner wall of the pipe fitting is greater than the thickness between the annular winding grooves (3021) and the inner wall of the pipe fitting.

4. A leak-proof and copper-overflow-proof electric fusion pipe fitting according to claim 1, characterized in that, The area of the pipe body (1) below the inner connection end (202) of the terminal (2) is a cold zone (101), and the temperature of the cold zone (101) during fusion welding is lower than that of the electrofusion melting zone part (3), which is used to block the flow of the molten glue in the electrofusion melting zone part (3) and prevent the molten glue from overflowing.

5. A leak-proof and copper-overflow-proof electrofusion fitting according to claim 1, characterized in that, The pipe body (1) further includes a column sleeve located on the outer wall of the pipe body (1) for protecting the outer connection end (201).

6. The leak-proof and copper-overflow-proof electrofusion pipe fitting according to claim 1, wherein, The pipe body (1) further includes a limiting block (102) for limiting the inserted pipe at the inner wall center of the pipe body (1).

7. The leak-proof and copper-overflow-proof electrofusion pipe fitting according to claim 6, characterized in that, A preset distance is set between the limiting block (102) and the annular winding part (302) to prevent insufficient insertion depth of the pipe.

8. The anti-leakage and copper-overflowing glue electric melting pipe fitting according to claim 7, wherein The limiting block (102) is a cuboid.

9. The leak-proof and copper-overflow-proof electrofusion pipe fitting according to claim 1, characterized in that, The pipe body (1) further includes flared parts (103) at both ends, and the inner diameter of the flared parts (103) is greater than the inner diameter of the electrofusion melting zone part (3) to facilitate the insertion of the pipe.

10. The leak-proof and copper-overflow-preventing electrofusion pipe fitting according to claim 2, wherein, The stepped annular winding part (301) further includes an annular wall (3012) located on its side close to the terminal (2) for separating the terminal (2) from the stepped annular winding grooves (3011); during the production of the pipe fitting, the two levels of steps of the stepped annular winding part (301) and the annular wall (3012) axially position the heating wire (4) wound on the stepped annular winding grooves (3011).

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