A hot melting method and hot melting device for large diameter pipes

Abstract

The present application discloses a hot melt method and a hot melter for large-diameter pipes. It belongs to the technical field of hot melters. The structure can meet the radial heating method required for hot melting of large-diameter pipes, thereby balancing the melting degree of pipes and pipe fittings, and facilitating the welding of pipes and pipe fittings, reducing the difficulty of operation, improving work efficiency, and having a simple structure and being easy to use. The method comprises: preheating; the pipe fitting is sleeved on the inner melting die head of the inner melting component, and the pipe is sleeved on the outer melting die head of the outer melting component; the inner melting component and the outer melting component are heated at the same time, and at the same time, the inner melting die head performs radial pressure treatment on the inner wall of the pipe fitting outward, and the outer melting die head performs radial extrusion treatment on the outer wall of the pipe inward; after the inner surface of the pipe fitting and the outer surface of the pipe have reached a predetermined melting degree, the pipe fitting and the pipe are pulled out from the hot melter, and the melting end of the pipe is quickly sleeved on the melting end of the pipe fitting.

Description

Technical Field

[0001] The invention relates to the technical field of hot melters, in particular to a hot melt method and a hot melter used for large-diameter pipes. Background Art

[0002] A hot melter is a professional welding tool used to heat and melt thermoplastic plastic pipes and molds and then connect them. The hot melter plays a vital role in the process of connecting pipes and accessories. It is mainly used for welding pipes such as PVC pipes and PE pipes. The hot melters on the market are still very useful for pipes with a diameter less than 40mm, but for welding pipes with a diameter greater than 90mm, its defects are also extremely obvious.

[0003] In actual use, it is necessary to design a pipeline layout for pipes. At this time, pipe fittings are needed to be used as adapters. The working principle of a common hot melter is: the operator holds the pipe in one hand and the fitting in the other hand and simultaneously sleeves the fitting and the pipe on the fusion joints on the left and right ends of the hot melter. The hot melter heats the outer surface of the pipe and the inner surface of the fitting respectively, and then sleeves the heated fitting and the pipe to achieve fusion.

[0004] During actual operation, technicians in this field found that the above welding method is suitable for small-diameter pipes, but has the following defects for welding large-diameter pipes:

[0005] 1. Since the heating time of large-diameter pipes is long, and the wall thickness of pipes and pipe fittings is different, the heating degree of pipes reaches the requirement in the same time, but the heating degree of pipe fittings is insufficient, the welding effect is poor and easy to fall off; if the heating time is extended, the pipe is easy to melt and deform, resulting in the scrapping of materials;

[0006] Second: Large-diameter pipes are not easy to grasp and are easy to slip out of the hands. Moreover, the operator needs to hold the pipe in one hand and the pipe fitting in the other hand and simultaneously sleeve the pipe fitting and the pipe on the fusion joints on the left and right ends of the hot melter. The construction is more difficult, and the strength required to sleeve the heated pipe fittings is greater, which has a greater impact on the fusion effect;

[0007] 3. When large-diameter pipes and fittings are sleeved together, it is easy to squeeze part of the material on the inner wall of the pipe fittings to cause bulges. The bulges will affect the flow rate of the fluid in the pipe. At this time, the fluid will exert force on the interface. Over time, the pipe at the weld will fall off.

[0008] The traditional hot melter heats the hot melt die head to a certain temperature and then applies axial pressure to the pipe and fittings to force the outer wall of the pipe and the inner wall of the fitting to melt gradually at the same time. After a certain degree of melting, the pipe head with the melted outer wall surface is inserted into the socket of the fitting with the melted inner wall surface. The inner and outer molten layers are squeezed and compacted against each other by the predetermined taper of the inner and outer die heads, so that the pipes and fittings are firmly welded together to achieve good sealing and pressure-bearing effects.

[0009] The disadvantage is that the pipes and fittings apply axial pressure to the hot melt die head at the same time, and the pipes and fittings on both sides are under exactly the same pressure. However, due to various reasons: 1. The melting allowance on both sides is often different; 2. The weight of the pipe fitting die head is light.

[0010] At the same temperature, the heat carried is less, and the cross-sectional area of ​​the pipe fittings is much larger than that of the pipe, so the heat is transferred and lost more; on the pipe side, it is just the opposite. The hot melt die head is relatively heavy, and the die head contains more heat at the same temperature. The cross-sectional area of ​​the pipe is usually smaller, so the heat transfer loss is less. Therefore, the melting speed on both sides is usually fast or slow, which will affect the quality of the construction. At the same time, when the die head is pressed in, it often produces a large axis deviation and shaking due to the operator or clamping tools, resulting in uneven melting of the bonding surface and insufficient effective contact surface, resulting in quality accidents.

[0011] This progressive hot melt method will push a certain amount of molten waste slag to the inner wall of the pipe fitting and the root of the pipe socket, affecting the smoothness of the inner wall and the appearance of the pipe fitting. Another disadvantage of this method is that when welding larger diameter pipes, a very large axial thrust is required to melt the pipe fittings. Usually, it is difficult to operate when the specification is 110mm. Therefore, for specifications above 110mm, only butt welding with relatively low welding strength or electric fusion pipe fittings with higher cost and poor strength can be selected. The inner wall of the socket of the electric fusion joint is covered with electric wire. The resistance wire cooperates with the pipe in a small gap. The pipe is pre-inserted into the fitting and then the resistance wire is energized and heated for a certain period of time so that the joint of the pipe and the fitting is melted and bonded into one to achieve a sealing and pressure-bearing effect. Its main disadvantages are that the manufacturing cost of the fittings is high, the cost of large-sized PE pipes is high, the dimensional tolerance after processing is large, and it is difficult to cooperate with the fittings to form an ideal small gap state. It is often necessary to match them in batches, which wastes manpower and material resources. In addition, there is no compression force on the joint surface of the pipe and the fitting, which makes the pressure-bearing strength of the weld poor, not to mention the welding of larger diameter pipes.

[0012] Therefore, a hot melting method and a hot melter for large-diameter pipes are needed to overcome the above-mentioned shortcomings. Summary of the invention

[0013] The present invention aims to solve the above-mentioned shortcomings of existing hot melters and provide a radial heating method that can meet the hot melting needs of large-diameter pipes, thereby balancing the melting degree of pipes and pipe fittings, facilitating the welding of pipes and pipe fittings, reducing the difficulty of operation, improving work efficiency, and having a simple structure and easy to use. A hot melting method and hot melter for large-diameter pipes.

[0014] The above technical problems are solved by the following technical solutions:

[0015] A hot melting method for large-diameter pipes, the method comprising: preheating;

[0016] The pipe fitting is sleeved on the inner melt die head of the inner melt component, and the pipe is sleeved on the outer melt die head of the outer melt component;

[0017] The inner melting assembly and the outer melting assembly are heated simultaneously, and the inner melting die head performs radial pressure treatment on the inner wall of the pipe fitting outward, and the outer melting die head performs radial extrusion treatment on the outer wall of the pipe inward;

[0018] After the inner surface of the pipe fitting and the outer surface of the pipe material have reached a predetermined melting degree, the pipe fitting and the pipe material are pulled out from the hot melter, and the melted end of the pipe material is quickly sleeved on the melted end of the pipe fitting.

[0019] As a further solution of the present invention: the length of the pipe piece sleeved on the inner melt die head is the same as the length of the pipe sleeved on the outer melt die head.

[0020] As a further solution of the present invention: the hot melt surfaces of the inner melt die head and the outer melt die head are arranged obliquely at a certain inclination angle.

[0021] A hot melter comprises a fixing part, a driving component, an inner melt component and an outer melt component; the inner melt component comprises an inner melt chute plate, an inner support core and a plurality of inner melt die heads with heating tubes, the plurality of inner melt die heads are slidably embedded in the inner melt chute plate through a plurality of springs and are evenly distributed in a ring shape, the inner support core is sleeved on the inner melt die head and is fixedly mounted on the inner melt chute plate; the outer melt component comprises an outer melt chute plate, a tightening sleeve and a plurality of outer melt die heads with heating tubes, the plurality of outer melt die heads are slidably embedded in the outer melt chute plate through a plurality of springs and are evenly distributed in a ring shape, the tightening sleeve is sleeved on the outer melt die head and is fixedly mounted on the outer melt chute plate; the inner melt chute plate and the outer melt chute plate are connected to the outer melt chute plate through the inner melt chute plate. The inner and outer melt heads are fixedly connected by a plurality of inner and outer melt heads in series with bolts, and the driving assembly is installed between the inner melt chute plate and the outer melt chute plate; the fixing part is fixedly installed on the inner melt chute plate; the inner melt die head comprises an inner melt sliding part and an inner melt die part, and the inner melt die part is fixedly installed at the lower end of the inner melt sliding part, and the inner melt sliding part is embedded with the inner melt chute, and the outer surface of the inner melt die part is arranged as a curved surface with the left side lower and the right side higher; the outer melt die head comprises an outer melt sliding part and an outer melt die part, and the outer melt die part is fixedly installed at the lower end of the outer melt sliding part, and the outer melt sliding part is embedded with the outer melt chute, and the inner surface of the outer melt die part is arranged as a curved surface with the left side higher and the right side lower.

[0022] As a further solution of the present invention: the driving assembly includes a driving handle and a driving screw pair; the driving handle is rotatably sleeved on the driving screw pair. The driving screw pair includes a driving screw and a driving nut that are matched and connected to each other.

[0023] As a further solution of the present invention: the inner and outer fusion head series bolt includes a fixed nut, a reinforcing screw, a threaded rod and a movable nut; the fixed nut is fixedly connected to the left end of the reinforcing screw, the threaded rod is fixedly connected to the right end of the reinforcing screw, and the movable nut and the threaded rod are connected by threads; the inner fusion slot plate is fixedly installed between the fixed nut and the reinforcing screw, and the outer fusion slot plate is fixedly installed between the reinforcing screw and the movable nut.

[0024] As a further solution of the present invention: the inner melt chute plate is provided with a plurality of inner melt connection holes for connecting the inner and outer melt heads in series with bolts; the outer melt chute plate is provided with a plurality of outer melt connection holes for connecting the inner and outer melt heads in series with bolts; the plurality of inner melt connection holes and the plurality of outer melt connection holes are arranged in a one-to-one correspondence.

[0025] As a further solution of the present invention: a plurality of annularly distributed inner melt chutes are provided at the left end of the inner melt chute plate, the inner melt chutes are arranged in a one-to-one correspondence with the inner melt die head, and an inner melt spring limiting hole for a limiting spring is provided on the inner melt chute, and the spring is limited by a screw.

[0026] As a further solution of the present invention: a plurality of annularly distributed external melt chutes are provided at the right end of the external melt chute plate, the external melt chutes are arranged in a one-to-one correspondence with the external melt die head, and a spring is provided on the external melt chute.

[0027] As a further solution of the present invention: the fixing member is a fixed handle.

[0028] The present invention can achieve the following effects:

[0029] The present invention provides a hot melting method and a hot melter for large-diameter pipes, which can meet the radial heating requirements of large-diameter pipes for hot melting, thereby balancing the melting degree of pipes and pipe fittings, and facilitating the welding of pipes and pipe fittings, reducing the difficulty of operation, improving work efficiency, having a simple structure and being easy to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the overall structure of the hot melt device in the present invention;

[0031] Figure 2 yes Figure 1 Schematic diagram of the explosion structure;

[0032] Figure 3 It is a schematic structural diagram of the driving screw pair in the present invention;

[0033] Figure 4 It is a schematic diagram of the structure of the inner and outer fusion heads in series with the bolt in the present invention;

[0034] Figure 5 It is a schematic diagram of the structure of the inner melt chute plate in the present invention;

[0035] Figure 6 It is a schematic diagram of the structure of the external melting chute plate in the present invention;

[0036] Figure 7 It is a schematic structural diagram of the internal melt die head in the present invention;

[0037] Figure 8 It is a schematic diagram of the structure of the foreign melt die head of the present invention;

[0038] Fig. 9 It is a cross-sectional view of the use effect of the hot melt device in the present invention.

[0039] The reference numerals in the figure are: inner melt component 1, outer melt component 2, drive component 3, fixing part 4, inner melt chute plate 11, inner support core 13, heating tube 7, inner melt die head 12, outer melt chute plate 21, tightening sleeve 24, outer melt die head 22, insulation pad 23, spring 6, inner and outer melt head series bolts 5, inner melt sliding part 122, inner melt mold part 121, outer melt sliding part 222, outer melt mold part 221, drive handle 31, drive screw pair 32, drive screw 321, drive nut 322, fixing nut 51, reinforcing screw 52, ​​threaded rod 53, movable nut 54, inner melt connecting hole 113, outer melt connecting hole 213, inner melt chute 111, inner melt spring limiting hole 112, outer melt chute 211, outer melt spring mounting groove 212. DETAILED DESCRIPTION

[0040] The present invention is described in detail and completely below through specific embodiments in conjunction with the accompanying drawings.

[0041] Embodiment, a hot-melt method for large-diameter pipes, the method comprising: preheating; the pipe fitting is sleeved on the inner melt die head 12 of the inner melt component 1, and the pipe is sleeved on the outer melt die head 22 of the outer melt component 2; the inner melt component 1 and the outer melt component 2 are heated simultaneously, and the inner melt die head 12 radially pressurizes the inner wall of the pipe fitting outward, and the outer melt die head 22 radially extrudes the outer wall of the pipe inward; after the inner surface of the pipe fitting and the outer surface of the pipe have reached a predetermined melting degree, the pipe fitting and the pipe are pulled out from the hot melter, and the melted end of the pipe is quickly sleeved on the melted end of the pipe fitting.

[0042] The length of the pipe piece sleeved on the inner melt die head is the same as the length of the pipe material sleeved on the outer melt die head. The hot melt surfaces of the inner melt die head and the outer melt die head are both arranged in an inclined shape with a certain inclination angle.

[0043] A hot melt device used in the above method, see Figure 1-8As shown, it includes a fixing part 4, a driving component 3, an inner melt component 1 and an outer melt component 2; the inner melt component 1 includes an inner melt chute plate 11, an inner support core 13 and a plurality of inner melt die heads 12 with heating tubes 7, and the plurality of inner melt die heads 12 are slidably embedded in the inner melt chute plate 11 through a plurality of springs 6 and are evenly distributed in an annular shape, and the inner support core 13 is sleeved on the inner melt die head 12 and fixedly installed on the inner melt chute plate 11; the outer melt component 2 includes an outer melt chute plate 21, a tightening sleeve 24 and a plurality of outer melt die heads 22 with heating tubes 7, and the plurality of outer melt die heads 22 are slidably embedded in the outer melt chute plate 21 through a plurality of springs 6 and are evenly distributed in an annular shape, and the tightening sleeve 24 is sleeved on the outer melt die head 22 and fixedly installed on the outer melt chute plate 21; the inner melt chute plate 11 and the outer melt chute plate 21 are slidably embedded in the outer melt chute plate 21 through a plurality of inner and outer melt The head is fixedly connected with the series bolts 5, and the driving assembly 3 is installed between the inner melt chute plate 11 and the outer melt chute plate 21; the fixing part 4 is fixedly installed on the inner melt chute plate 11; the inner melt die head 12 includes an inner melt sliding part 122 and an inner melt die part 121, and the inner melt die part 121 is fixedly installed at the lower end of the inner melt sliding part 122, and the inner melt sliding part 122 is embedded with the inner melt chute 111, and the outer surface of the inner melt die part 121 is arranged as a curved surface with the left side lower and the right side higher; the outer melt die head 22 includes an outer melt sliding part 222 and an outer melt die part 221, and the outer melt die part 221 is fixedly installed at the lower end of the outer melt sliding part 222, and the outer melt sliding part 222 is embedded with the outer melt chute 211, and the inner surface of the outer melt die part 221 is arranged as a curved surface with the left side higher and the right side lower.

[0044] See also Figure 2-3 As shown, the driving assembly 3 includes a driving handle 31 and a driving screw pair 32; the driving handle 31 is rotatably sleeved on the driving screw pair 32. The driving screw pair 32 includes a driving screw 321 and a driving nut 322 which are matched and connected to each other.

[0045] See also Figure 4 As shown, the inner and outer melting head series bolt 5 includes a fixed nut 51, a reinforcing screw 52, ​​a threaded rod 53 and a movable nut 54; the fixed nut 51 is fixedly connected to the left end of the reinforcing screw 52, ​​the threaded rod 53 is fixedly connected to the right end of the reinforcing screw 52, ​​and the movable nut 54 is connected to the threaded rod 53 by threads; the inner melting slot plate 11 is fixedly installed between the fixed nut 51 and the reinforcing screw 52, ​​and the outer melting slot plate 21 is fixedly installed between the reinforcing screw 52 and the movable nut 54.

[0046] See also Figure 2As shown, the inner melt chute plate 11 is provided with a plurality of inner melt connection holes 113 for connecting the inner and outer melt heads in series with the bolts 5; the outer melt chute plate 21 is provided with a plurality of outer melt connection holes 213 for connecting the inner and outer melt heads in series with the bolts 5; the plurality of inner melt connection holes 113 and the plurality of outer melt connection holes 213 are arranged in a one-to-one correspondence.

[0047] See also Figure 5 As shown, the left end of the inner melt slide plate 11 is provided with a plurality of inner melt slide grooves 111 distributed in a ring shape, and the inner melt slide grooves 111 are arranged in a one-to-one correspondence with the inner melt die head 12. The inner melt slide groove 111 is provided with an inner melt spring limiting hole 112 for the limiting spring 6, and the spring 6 is limited by a screw.

[0048] See also Figure 6 As shown, a plurality of annularly distributed external melt chutes 211 are provided at the right end of the external melt chute plate 21. The external melt chute 211 is arranged in a one-to-one correspondence with the external melt die head 22. An external melt spring installation groove 212 for installing the spring 6 is provided on the external melt chute 211.

[0049] In this embodiment, the fixing member 4 is a fixed handle. The number of the inner melt die head 12 and the number of the outer melt die head 22 are both six. The number of the inner and outer melt die head series bolts 5 is three. The outer melt runner plate 21 located between the outer melt die heads 22 is provided with an insulating pad 23 for heat insulation.

[0050] In the embodiment of the present invention, the outer surface of the inner melt die part 121 is arranged as a curved surface with the left side lower and the right side higher, and the inner surface of the outer melt die part 221 is arranged as a curved surface with the left side higher and the right side lower, so that the melting and heating of the pipe and the pipe fittings are facilitated during the melting process and the contact area is increased; the melting degrees of the pipe and the pipe fittings are balanced by the six groups of sliding inner melt die heads 12 and the six groups of sliding outer melt die heads 22; at the same time, the inner melt die head 12 provides an outward force to the pipe fittings, and the outer melt die head 22 provides an inward force to squeeze the pipe, which not only facilitates the balancing of the melting degrees of the pipe and the pipe fittings during melting, but also reduces the difficulty of operation during welding, thereby improving work efficiency.

[0051] The method of the present invention utilizes a special hot-melt die head that can shrink and expand radially to heat the outer wall of the pipe and the inner wall of the pipe fitting respectively. Since the outer melt component 2 of the pipe sleeve is expanded by the six-part outer melt component 2, the pipe is directly sleeved into the required hot-melt length, and the inner melt die head 12 is directly inserted into the required depth of the inner wall of the pipe fitting by reducing the outer diameter. After the pipe fitting is inserted into place, the pipe fitting die head is expanded by driving the transmission to heat the inner wall of the pipe fitting, and at the same time, the pipe fitting die head is contracted by the driven mechanism to heat the outer wall of the pipe.

[0052] The prior art adopts a progressive side-sleeve heating method on the hot melter. The disadvantage of this axial heating method is that the pipes and fittings simultaneously apply axial pressure to the hot melt die head, and the pipes and fittings on both sides are under exactly the same pressure. However, due to various reasons: 1. The melting margins on both sides are often different, 2. The pipe fitting die head is light in weight, and carries less heat at the same temperature, while the cross-sectional area of ​​the pipe fitting is much larger than that of the pipe, and the heat is transferred and lost more. On the pipe side, it is just the opposite. The hot melt die head is relatively heavy, and contains more heat at the same temperature. The cross-sectional area of ​​the pipe is usually smaller in comparison, and the heat transfer loss is less. Therefore, the melting speed on both sides is usually fast or slow, which will affect the quality of the construction. The present invention adopts the method of preheating first, then sleeve connection, and finally shrinking and expanding to heat. The present invention adopts radial heating to meet the hot melting requirements of large-diameter pipes.

[0053] During the hot melt operation, the driving device does not need to drag the heavy pipes and fittings but directly pressurizes and heats the surface of the part that needs to be melted. The pressure can be applied by manual lever or servo electric drive. Moreover, the heating and pressurization of the die heads on both sides are relatively independent and controllable, which is very beneficial to the control of the melting state and matching size of the pipes and fittings. That is, when the melting reaches the mechanical limit, the resistance size can be sensed by rotating the die head or the torque indicator can be used to judge whether the melting state is in place. At the same time, the phenomenon of cold welding caused by uneven melting speed and axis deviation when the die head is pushed in, which is easy to occur during traditional welding, can be improved to the greatest extent.

[0054] At the same time, because a gap of about 1mm will be generated at the end of melting of the two sides of the die heads, the molten waste will be squeezed in. Since the gap between the inner and outer die heads is at a certain angle to the axis, when the die head is rotated to verify the melting state and the die head is pulled out after melting, the waste will be left in the gap of the die head and taken out. Because the matching taper of the traditional die head is retained, the tolerance of the size of pipes and fittings can be adapted to a wide range, so it is easier to achieve the ideal welding effect, and at the same time it can save construction costs. It is strong and has high pressure resistance, few potential safety hazards, and is smooth inside and outside. It is particularly suitable for hot-melt connection of PE drainage pipes with high requirements for smooth inner walls. At the same time, it can also be used for large-diameter water supply and drainage pipes, and even PE wire mesh skeleton pipes that could only be electro-fused before.

[0055] The present invention provides a hot melting method and a hot melter for large-diameter pipes, which can meet the radial heating requirements of large-diameter pipes for hot melting, thereby balancing the melting degree of pipes and pipe fittings, and facilitating the welding of pipes and pipe fittings, reducing the difficulty of operation, improving work efficiency, having a simple structure, being easy to use, and having high reliability.

[0056] The above description is only a preferred embodiment of the present invention, and does not limit the patent protection scope of the present invention. Any equivalent structural transformation made by using the contents of the present invention and the drawings, directly or indirectly used in other related technical fields, is also included in the protection scope of the present invention.

Claims

1. A hot melt device, characterized in that: The invention relates to a method for producing a die-casting machine which is convenient for use in producing a die-casting machine and a method for producing a die-casting machine having a plurality of moving parts, wherein the moving parts are arranged on a circle and a plurality of moving parts are connected to the die-casting machine by the plurality of moving parts being connected to the die-casting machine. The movable part is embedded in the inner melt chute, and the outer surface of the inner melt mold part is arranged in a curved surface with a left side lower than the right side; the outer melt mold head comprises an outer melt sliding part and an outer melt mold part, and the outer melt mold part is fixedly installed at the lower end of the outer melt sliding part, and the outer melt sliding part is embedded in the outer melt chute, and the inner surface of the outer melt mold part is arranged in a curved surface with a left side higher than the right side, and the driving assembly comprises a driving handle and a driving screw pair; the driving handle is rotatably sleeved on the driving screw pair; the driving screw pair comprises a driving screw and a driving nut which are matched with each other, and the inner and outer melt head series bolts comprise a fixing nut, a reinforcing screw, a threaded rod and a movable nut; the fixing nut is fixedly connected to the left end of the reinforcing screw, the threaded rod is fixedly connected to the right end of the reinforcing screw, and the movable nut is connected to the threaded rod by a thread; the inner melt chute plate is fixedly installed between the fixing nut and the reinforcing screw, and the outer melt chute plate is fixedly installed between the reinforcing screw and the movable nut.

2. The hot melt device according to claim 1, characterized in that: The inner melt chute plate is provided with a plurality of inner melt connection holes for connecting the inner and outer melt heads in series with bolts; the outer melt chute plate is provided with a plurality of outer melt connection holes for connecting the inner and outer melt heads in series with bolts; the plurality of inner melt connection holes and the plurality of outer melt connection holes are arranged in a one-to-one correspondence.

3. The hot melt device according to any one of claims 1 to 2, characterized in that: The left end of the inner melt chute plate is provided with a plurality of inner melt chute grooves distributed in a ring shape, the inner melt chute grooves are arranged in a one-to-one correspondence with the inner melt die head, the inner melt chute groove is provided with an inner melt spring limiting hole for a limiting spring, and the spring is limited by a screw.

4. The hot melt device according to any one of claims 1 to 2, characterized in that: The right end of the external melt chute plate is provided with a plurality of external melt chutes distributed in a ring shape, the external melt chutes are arranged in a one-to-one correspondence with the external melt die head, and the external melt chute is provided with an external melt spring installation groove for installing a spring.

5. The hot melt device according to claim 1, characterized in that: The fixing member is a fixing handle.

6. A hot melt method for large diameter pipes, characterized in that: Using any one of the hot melters as claimed in claims 1 to 5 to hot melt large diameter pipes; The pipe fitting is sleeved on the inner melting die head of the inner melting assembly, and the pipe is sleeved on the outer melting die head of the outer melting assembly; the inner melting assembly and the outer melting assembly are heated at the same time, and the inner melting die head performs radial pressure treatment on the inner wall of the pipe fitting outward, and the outer melting die head performs radial extrusion treatment on the outer wall of the pipe inward; After the inner surface of the pipe fitting and the outer surface of the pipe material have reached a predetermined melting degree, the pipe fitting and the pipe material are pulled out from the hot melter, and the melted end of the pipe material is quickly sleeved on the melted end of the pipe fitting.

7. A hot melt method for large diameter pipes according to claim 6, characterized in that: The length of the pipe fitting sleeved on the inner melting die head is the same as the length of the pipe fitting sleeved on the outer melting die head.

8. A hot melt method for large diameter pipes according to claim 6, characterized in that: The hot melt surfaces of the inner melt die head and the outer melt die head are both arranged in an inclined shape with a certain inclination angle.

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