Polyamide coated connecting pipe and manufacturing process

Abstract

The application discloses a polyamide coating connecting pipeline and a manufacturing process, which comprises a polyamide connecting pipeline, a copper pipeline body flared part connected with the polyamide connecting pipeline port connecting part, a fixed ring groove formed on the outer surface of the polyamide connecting pipeline connecting part, and a buckle ring sleeve provided on the outer port of the copper pipeline body and forming an interface gap with the fixed ring groove; and a solder filling and sealing assembly arranged on the outer surface of the fixed ring groove and used for fixing the inner and outer parts of the interface gap through the cooperation of the molten and expanded solder ring piece and the rubber fireproof expanded ring piece, so that the copper pipeline body flared part and the polyamide connecting pipeline are fixed through the cooperation of the opening on the buckle ring sleeve and the material groove hole, and the interface gap is sealed through the outer sealing solder layer, thereby improving the structural strength of the connecting part of the polyamide connecting pipeline at both ends of the water pan and the copper pipeline installation part.

Description

Technical Field

[0001] This invention belongs to the field of refrigerator connection pipe technology, specifically relating to a polyamide coated connection pipe and its manufacturing process. Background Technology

[0002] To prevent excessive moisture in the refrigerator from causing icing, a drip tray is typically installed inside to collect condensate. This tray is usually located at the bottom of the refrigerator, near the back, and above the compressor. This placement effectively collects condensate from the refrigerator and freezer compartments, preventing it from contacting the compressor and damaging the motor. An evaporator tube is installed inside the drip tray to heat and evaporate the defrosting water. However, with rapid technological innovation in the refrigerator industry, the use of copper pipes and other non-ferrous metal tubing in refrigerators has become increasingly problematic. The oxidation and corrosion at the welded joints of copper pipes directly affect refrigerator quality. Furthermore, with rising prices of non-ferrous metals both domestically and internationally, replacing easily oxidized evaporator tubes with polyamide-coated steel pipes offers a price advantage over traditional copper pipes, while also reducing production costs for manufacturers.

[0003] For example, Chinese patent CN208704524U discloses an iron evaporator tube with a nylon coating, including an iron evaporator tube body; the outer periphery of the iron evaporator tube body is wrapped with a nylon coating, and an electrical heat shrink tubing is sleeved on the outer periphery of the nylon coating; the iron evaporator tube body is installed in the drip tray of a refrigerator; one end of the iron evaporator tube body is connected to the compressor exhaust pipe of the refrigerator, and the other end of the iron evaporator tube body is connected to the anti-condensation pipe of the refrigerator.

[0004] However, the above solution has the following shortcomings: The evaporator tube is coated with a polyamide layer on its outer surface to form a polyamide connecting pipe for corrosion protection. However, the compressor exhaust pipe is usually made of copper, which has a better heat transfer effect. Therefore, a transition installation is required at the connection between the polyamide connecting pipe and the compressor copper pipe. In order to facilitate the installation of the polyamide connecting pipe and the anti-condensation pipe, the two installation positions are called the connection points. After removing the polyamide coating from the outer surface of the connection point used for connection installation, it is installed with the flared copper pipe connection point. However, the existing polyamide connecting pipe connection points for water trays and external connection parts are usually sealed by welding the outer end of the interface gap with simple copper-phosphorus solder, silver-copper solder, copper-zinc solder, etc. There is no snap-fit ​​fixing structure inside the interface gap, resulting in low structural strength of the connection points at both ends of the polyamide connecting pipe for water trays and the copper pipe installation point. How to improve the structural strength of the connection points at both ends of the polyamide connecting pipe for water trays and the copper pipe installation point is a problem that needs to be solved at present. Summary of the Invention

[0005] The purpose of this invention is to provide a polyamide-coated connecting pipe and its manufacturing process to solve the problems existing in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A polyamide-coated connecting pipe, comprising:

[0008] A polyamide connecting tube is provided, with its two ends connected to the flared portion of a copper tube. A fixing annular groove is formed on the outer surface of the polyamide connecting tube's connection point, and a snap-fit ​​ring is fixedly fitted onto the outer end of the copper tube, forming an interface gap between the snap-fit ​​ring and the fixing annular groove.

[0009] A solder filling and sealing assembly is disposed on the outer surface of the fixing ring groove and is used to structurally fix the inside and outside of the interface gap.

[0010] Preferably, the polyamide connecting pipe is composed of a steel pipe layer, a galvanized layer, an adhesive layer and a polyamide coating from the inside out. The polyamide coating on the outer surface of the connection is removed, and the beveled edge of the constricted outer surface of the connection is designed to contact and fit with the beveled edge of the inner wall of the flared part of the copper pipe.

[0011] Preferably, the buckle ring is divided into an insertion part and an outer part. The insertion part contacts and adheres to the inner ring wall at the outer port of the flared part of the copper tube, and the outer part contacts and adheres to the outer surface at the outer port of the flared part of the copper tube. The insertion part and the outer part are provided with snap-fit ​​pieces on their opposite surfaces and are in contact with and locked to the inner and outer surfaces of the flared part of the copper tube. The inner wall of the fixing ring groove is provided with anti-disengagement grooves in a circumferential manner.

[0012] Preferably, the outer side wall of the buckle sleeve is provided with an opening that communicates with the outer end of the flared part of the copper tube, and the top wall of the buckle sleeve insertion part is provided with a material passage groove that communicates with the inner ring wall of the flared part of the copper tube.

[0013] Preferably, the solder filling and sealing assembly includes a solder ring and a rubber fireproof expansion ring respectively annularly sleeved on the fixed ring groove. The solder ring is located directly outside the anti-detachment groove. The outer surface of the rubber fireproof expansion ring is circumferentially arranged with a lifting baffle plate. The lifting baffle plate is set above the anti-detachment groove and fixedly set with the inner ring surface of the solder ring. The bottom end face of the lifting baffle plate is symmetrically set with a card and inserted into the corresponding anti-detachment groove for anti-detachment fixation. After the flared part of the copper tube is indirectly heated by the oxy-acetylene torch, the solder ring melts and flows into the anti-detachment groove to assist in fixing the card. At the same time, the rubber fireproof expansion ring expands thermally after being indirectly heated by the oxy-acetylene torch and pushes the lifting baffle plate so that the molten solder ring passes into the material passage hole and solidifies with the inner ring wall of the flared part of the copper tube.

[0014] The solder filling and sealing assembly also includes an outer sealing solder layer, which is applied to the outer surface of the opening and the polyamide connecting pipe joint by an oxyacetylene torch. The outer surface of the polyamide connecting pipe joint is provided with a heat insulation ring that contacts the cut polyamide coating port. The outer sealing solder layer passes through the opening and solidifies with the outer edge of the copper pipe port. The outer port of the lifting baffle is provided with a clamp, and the outer sealing solder layer wraps and fixes the clamp.

[0015] A manufacturing process includes the following steps:

[0016] A. The polyamide connecting pipe is cut to the required length using a rotary cutter, and a constriction is formed at the cut. Then, the polyamide coating and galvanized layer at the connection point of the polyamide connecting pipe are removed using a fiber abrasive wheel, exposing the steel pipe layer. At the same time, a dust removal device is used to purify the powder generated during the removal of the polyamide coating. The heat insulation ring is then fixed to the polyamide coating port and fitted onto the outer surface of the polyamide connecting pipe connection by adhesive bonding. An annular fixing groove is chiseled on the outer surface of the polyamide connecting pipe connection by an external cutting machine, and four anti-detachment grooves are chiseled circumferentially on the inner wall of the fixing groove.

[0017] B. Insert the solder ring and the rubber fireproof expansion ring into the fixed ring groove in sequence, and fix the four lifting folding plates on the top of the rubber fireproof expansion ring. At the same time, place the folded edge of the lifting folding plate above the anti-detachment groove and fix it on the inner ring surface of the solder ring. The card located on the bottom end of the lifting folding plate is inserted into the anti-detachment groove.

[0018] C. The outer end of the copper tube is flared using an external flaring tool to form a flared section. A snap-fit ​​ring is then fitted onto the outer edge of the flared section and secured with a snap-fit ​​spring. The connection point of the polyamide connector is inserted into the flared section, ensuring the constricted portion of the connection point contacts and the beveled edge of the inner ring wall of the flared section. The solder ring and the rubber fire-resistant expansion ring from step B are positioned between the inner ring surfaces of the snap-fit ​​ring insertion section, ensuring the outer surface of the solder ring faces the material passage hole. The outer surface of the flared section is heated using an oxy-acetylene torch, melting the solder ring and allowing it to flow into the anti-detachment groove for further securing the snap-fit. Simultaneously, the rubber... After being indirectly heated by an oxy-acetylene torch, the fire-resistant expansion ring expands thermally and pushes up the baffle plate, allowing the molten solder ring to pass into the feed groove and solidify with the inner ring wall of the flared part of the copper tube. Then, the solder is passed through the oxy-acetylene torch and placed as an outer sealing solder layer between the opening and the outer surface of the polyamide connecting pipe joint. The outer sealing solder layer solidifies and seals the clamp, opening, and interface gaps after cooling. At the same time, the outer side of the outer sealing solder layer extends to the side surface of the heat insulation ring in step A, providing anti-corrosion coverage to the exposed steel pipe layer at the polyamide connecting pipe joint, thus completing the installation and manufacturing of the polyamide connecting pipe joint and the flared part of the copper tube.

[0019] Compared with the prior art, the beneficial effects of the present invention are: by the cooperation of the molten and expanded solder ring and the rubber fireproof expansion ring, the copper tube flared part and the polyamide connecting tube are fixed together by the cooperation of the opening on the snap ring sleeve and the material passage hole, and the interface gap is sealed by the external sealing solder layer, thereby improving the structural strength of the connection at both ends of the polyamide connecting tube for the water receiving tray and the installation of the copper tube. Attached Figure Description

[0020] Figure 1 This is a cross-sectional schematic diagram of the connection area between the polyamide connecting tube and the copper tube body of the present invention;

[0021] Figure 2 for Figure 1 A magnified view of a portion of the buckle ring area;

[0022] Figure 3 for Figure 2 A schematic diagram of the melting state of the solder ring and the state of the rubber fireproof expansion ring after thermal expansion.

[0023] Figure 4 A schematic diagram of the sectional view of the polyamide connecting pipe and the copper pipe body in their mating state;

[0024] Figure 5 for Figure 4 A magnified view of the buckle loop area at point A;

[0025] Figure 6 for Figure 4 A schematic diagram of the structure during the removal of the solder ring, the rubber fireproof expansion ring, and the lifting folding plate.

[0026] In the diagram: 1. Polyamide connecting pipe; 2. Copper pipe body; 3. Fixing ring groove; 4. Snap ring sleeve; 5. Clip spring; 6. Opening; 7. Material passage hole; 8. Solder ring; 9. Rubber fireproof expansion ring; 10. Lifting folding plate; 11. Clip; 12. External sealing solder layer; 13. Heat insulation ring; 14. Clamp; 101. Anti-detachment groove; 201. Steel pipe layer; 202. Galvanized layer; 203. Adhesive layer; 204. Polyamide coating. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0028] Please see Figure 1-6 The present invention provides a technical solution:

[0029] Example 1:

[0030] A polyamide-coated connecting pipe, comprising:

[0031] A polyamide connecting pipe 1 is connected at both ends to the flared portion of a copper pipe body 2, forming a connecting pipe as a whole. A fixing annular groove 3 is formed on the outer surface of the connection point of the polyamide connecting pipe 1, and a snap-fit ​​ring 4 is fixedly fitted onto the outer end of the copper pipe body 2, forming an interface gap between the snap-fit ​​ring 4 and the fixing annular groove 3; and

[0032] Solder filling and sealing assembly is disposed on the outer surface of the fixing ring groove 3 and is used to structurally fix the interface gap inside and outside.

[0033] Example 2:

[0034] Based on Example 1, the polyamide connecting pipe 1 is composed of a 1mm thick steel pipe layer 201, a 0.5mm thick galvanized layer 202, a 0.3mm thick adhesive layer 203, and a 2mm thick polyamide coating 204 from the inside out. The polyamide coating 204 has excellent corrosion resistance. The combination of the polyamide coating 204 and the galvanized layer 202 enables the steel pipe layer 201 to have good anti-corrosion performance. The polyamide coating 204 on the outer surface of the connection of the polyamide connecting pipe 1 is removed, and the beveled edge of the constricted outer surface of the connection is designed to contact and fit with the beveled edge of the inner wall of the flared part of the copper pipe body 2.

[0035] Example 3:

[0036] Based on Example 1, the snap ring sleeve 4 is divided into an insertion part and an outer part. The insertion part has a cylindrical structure, and the cross-sectional diameter of the inner ring of the insertion part is larger than the cross-sectional diameter of the connection point of the polyamide connecting tube 1. The insertion part contacts and adheres to the inner ring wall at the outer port of the flared part of the copper tube body 2, such as... Figure 2 As shown, the outer sleeve has a folded ear structure, and the buckle ring 4 is made of elastic steel, so that the insertion part and the outer sleeve have a mutual resetting elastic force, which facilitates the initial fixation of the buckle ring 4 and the outer edge of the flared part of the copper tube 2. The outer sleeve contacts and fits against the outer surface of the outer port of the flared part of the copper tube 2, and the insertion part and the outer sleeve are both circumferentially provided with snap springs 5 ​​on their opposite surfaces and contact and snap-fit ​​with the inner and outer surfaces of the flared part of the copper tube 2. The snap springs 5 ​​are arc-shaped spring structures, which can improve the connection and fixing effect of the buckle ring 4. The inner wall of the fixing ring groove 3 is circumferentially provided with anti-detachment grooves 101, and the cross section of the anti-detachment grooves 101 is a dovetail groove structure.

[0037] The outer side wall of the buckle sleeve 4 is provided with an opening 6 that communicates with the outer end of the flared part of the copper tube body 2. The top wall of the insertion part of the buckle sleeve 4 is provided with a material passage hole 7 that communicates with the inner ring wall of the flared part of the copper tube body 2. The material passage holes 7 are in a group of four.

[0038] The solder filling and sealing assembly includes a solder ring 8 and a rubber fireproof expansion ring 9, which are respectively annularly fitted onto the fixed ring groove 3. The solder ring 8 is located directly outside the anti-detachment groove 101. The outer surface of the rubber fireproof expansion ring 9 is circumferentially arranged with lifting baffles 10. The rubber fireproof expansion ring 9 uses ethylene propylene rubber fireproof sealing strips produced by Hebei Xufeng Rubber Products Co., Ltd., and the full expansion temperature is set at 650℃. The lifting baffles 10 are set above the anti-detachment groove 101 and fixedly installed with the inner ring surface of the solder ring 8. The bottom end face of the lifting baffles 10 is symmetrically provided with a card 1. 1. It is inserted into the corresponding anti-detachment groove 101 and used for anti-detachment fixation. After the flared part of the copper tube body 2 is indirectly heated by the oxyacetylene welding torch, the solder ring 8 melts and flows into the anti-detachment groove 101 to assist in fixing the card 11. The solder ring 8 is made of silver-copper solder. The heating temperature of the oxyacetylene welding torch is controlled between 650-750℃. At the same time, the rubber fireproof expansion ring 9 is thermally expanded after being indirectly heated by the oxyacetylene welding torch and pushes and lifts the baffle plate 10 so that the molten solder ring 8 passes into the material passage hole 7 and solidifies with the inner ring wall of the flared part of the copper tube body 2.

[0039] The solder filling and sealing assembly also includes an outer sealing solder layer 12, which is formed by applying solder to the outer surface of the connection between the opening 6 and the polyamide connecting pipe 1 using an oxyacetylene torch. The outer sealing solder layer 12 is made of silver-copper solder. A heat insulation ring 13 is provided on the outer surface of the connection of the polyamide connecting pipe 1 and contacts the cut polyamide coating 204 port. The heat insulation ring 13 is made of either a glass magnesium fireproof board or a rock wool board. The outer sealing solder layer 12 passes through the opening 6 and solidifies with the outer edge of the copper pipe 2 port. A double-eared clamp 14 is welded to the outer port of the lifting baffle 10. The outer sealing solder layer 12 wraps and fixes the clamp 14. The clamp 14 can provide auxiliary fixation for the cooled and solidified outer sealing solder layer 12.

[0040] A manufacturing process includes the following steps:

[0041] A. The polyamide connecting pipe 1 is cut to the desired length using a rotary cutter, and a constriction is formed at the cut. Then, the polyamide coating 204 and galvanized layer 202 at the connection point of the polyamide connecting pipe 1 are removed using a fiber abrasive wheel, exposing the steel pipe layer 201. The surface hardness of the fiber abrasive wheel is higher than that of a wire brush, and the surface of the abrasive wheel is free of gaps. At the same time, a dust removal device is used to purify the powder generated during the removal of the polyamide coating 204. The dust removal device can be an industrial vacuum cleaner. The heat insulation ring 13 is then fixed to the end of the polyamide coating 204 and fixedly fitted onto the outer surface of the connection point of the polyamide connecting pipe 1 by adhesive bonding. An annular fixing groove 3 is chiseled on the outer surface of the connection point of the polyamide connecting pipe 1 using an external cutting machine, and four anti-detachment grooves 101 are chiseled circumferentially on the inner wall of the fixing groove 3.

[0042] B. Insert the solder ring 8 and the rubber fireproof expansion ring 9 into the fixed ring groove 3 in sequence, and fix the four lifting folding plates 10 on the top of the rubber fireproof expansion ring 9. At the same time, place the folded edge of the lifting folding plate 10 above the anti-detachment groove 101 and fix it on the inner ring surface of the solder ring 8. The card 11 located on the bottom end of the lifting folding plate 10 is inserted into the anti-detachment groove 101.

[0043] C. The outer end of the copper pipe body 2 is flared using an external flaring tool to form a flared section. The snap ring 4 is then fitted onto the outer edge of the flared section and secured with snap-fit ​​clips 5. The connection part of the polyamide connecting pipe 1 is inserted into the flared section, ensuring that the constricted part of the connection part and the inclined edge of the inner ring wall of the flared section are in contact and fit together. This utilizes the constriction generated during pipe cutting to improve the contact area and fixing effect between the connection part of the polyamide connecting pipe 1 and the copper pipe body 2. The solder ring 8 and the rubber fireproof expansion ring 9 from step B are positioned between the inner ring surfaces of the insertion part of the snap ring 4. Simultaneously, the outer surface of the solder ring 8 must face the material passage hole 7. The outer surface of the flared section is heated using an oxyacetylene torch, causing the solder ring 8 to melt and flow into the anti-detachment groove 101 to assist the clip 11. The rubber fireproof expansion ring 9 is fixed and, after being indirectly heated by the oxyacetylene welding torch, it expands thermally and pushes up the baffle plate 10, causing the molten welding ring 8 to pass into the material passage hole 7 and solidify with the inner ring wall of the flared part of the copper pipe body 2. Then, the welding material is placed in the outer sealing welding layer 12 between the opening 6 and the outer surface of the connection between the polyamide connecting pipe 1 and the opening 6 through the oxyacetylene welding torch. The outer sealing welding layer 12 seals the clamp 14, the opening 6 and the interface gap after cooling and solidification. At the same time, the outer side of the outer sealing welding layer 12 extends to the side surface of the heat insulation ring 13 in step A, and provides anti-corrosion coverage to the exposed steel pipe layer 201 at the connection of the polyamide connecting pipe 1. The installation and manufacturing of the connection of the polyamide connecting pipe 1 and the flared part of the copper pipe body 2 are completed, improving the structural strength of the connection at both ends of the polyamide connecting pipe 1 for the water receiving tray and the installation point of the copper pipe body 2.

[0044] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polyamide-coated connecting pipe, characterized in that, include: A polyamide connecting pipe (1) is connected at both ends to the flared part of a copper pipe body (2). A fixing annular groove (3) is provided on the outer surface of the connection of the polyamide connecting pipe (1), and a snap ring sleeve (4) is fixedly fitted on the outer end of the copper pipe body (2), forming an interface gap between the snap ring sleeve (4) and the fixing annular groove (3). Solder filling and sealing assembly, the solder filling and sealing assembly is disposed on the outer surface of the fixing ring groove (3) and is used to structurally fix the inside and outside of the interface gap; The buckle sleeve (4) is divided into an insertion part and an outer part. The insertion part is in contact with the inner ring wall at the outer port of the flared part of the copper tube (2), and the outer part is in contact with the outer surface at the outer port of the flared part of the copper tube (2). The insertion part and the outer part are provided with snap-fit ​​pieces (5) in a circumferential manner on opposite surfaces and are in contact with the inner and outer surfaces of the flared part of the copper tube (2) for snap-fit ​​and fixation. The inner wall of the fixing ring groove (3) is provided with anti-disengagement grooves (101) in a circumferential manner. The outer side wall of the buckle sleeve (4) is provided with an opening (6) that communicates with the outer end of the flared part of the copper tube (2). The top wall of the insertion part of the buckle sleeve (4) is provided with a material passage hole (7) that communicates with the inner ring wall of the flared part of the copper tube (2). The solder filling and sealing assembly includes a solder ring (8) and a rubber fireproof expansion ring (9) respectively annularly sleeved on the fixed ring groove (3). The solder ring (8) is located on the outside of the anti-detachment groove (101). A lifting baffle (10) is arranged circumferentially on the outer surface of the rubber fireproof expansion ring (9). The lifting baffle (10) is set above the anti-detachment groove (101) and fixedly set with the inner ring surface of the solder ring (8). A card (11) is symmetrically set on the bottom end of the lifting baffle (10) and inserted. The copper tube (2) is placed in the corresponding anti-detachment groove (101) and used for anti-detachment fixation. After the flared part of the copper tube (2) is indirectly heated by the oxyacetylene welding torch, the solder ring (8) melts and flows into the anti-detachment groove (101) to assist in fixing the card (11). At the same time, the rubber fireproof expansion ring (9) is thermally expanded after being indirectly heated by the oxyacetylene welding torch and pushes and lifts the baffle plate (10) so that the molten solder ring (8) passes into the material passage hole (7) and solidifies with the inner ring wall of the flared part of the copper tube (2).

2. The polyamide-coated connecting pipe according to claim 1, characterized in that: The polyamide connecting pipe (1) is composed of a steel pipe layer (201), a galvanized layer (202), an adhesive layer (203) and a polyamide coating (204) from the inside out. The polyamide coating (204) on the outer surface of the connection of the polyamide connecting pipe (1) is removed, and the beveled edge of the constricted outer surface of the connection is in contact with and fitted to the beveled edge of the inner wall of the flared part of the copper pipe body (2).

3. The polyamide-coated connecting pipe according to claim 1, characterized in that: The solder filling and sealing assembly also includes an outer sealing solder layer (12) where solder is placed between the opening (6) and the outer surface of the connection between the polyamide connecting tube (1) by an oxyacetylene torch. The outer surface of the connection between the polyamide connecting tube (1) is provided with a heat insulation ring (13) and contacts the port of the cut polyamide coating (204). The outer sealing solder layer (12) passes through the opening (6) and solidifies with the outer edge of the port of the copper tube body (2). The outer port of the lifting baffle (10) is provided with a clamp (14), and the outer sealing solder layer (12) wraps and fixes the clamp (14).

4. A manufacturing process for connecting pipes with a polyamide coating as described in any one of claims 1-3, characterized in that, Includes the following steps: A. The polyamide connecting pipe (1) is cut to the cutting length by means of a rotary cutter and a constriction is formed at the cut. Then, the polyamide coating (204) and galvanized layer (202) at the connection part of the polyamide connecting pipe (1) are removed by means of a fiber grinding wheel to expose the steel pipe layer (201). At the same time, the dust removal device is controlled to purify the powder generated during the removal of the polyamide coating (204). Then, the heat insulation ring (13) is fixed to the port of the polyamide coating (204) by adhesive bonding and fixedly fitted onto the outer surface of the connection of the polyamide connecting pipe (1). An annular fixing groove (3) is chiseled on the outer surface of the connection of the polyamide connecting pipe (1) by means of an external cutting machine, and four anti-detachment grooves (101) are chiseled circumferentially on the inner wall of the fixing groove (3). B, insert the solder ring (8) and the rubber fireproof expansion ring (9) into the fixed ring groove (3) in sequence, and fix the four lifting folding plates (10) on the top of the rubber fireproof expansion ring (9). At the same time, place the folded edge of the lifting folding plate (10) above the anti-detachment groove (101) and fix it on the inner ring surface of the solder ring (8). The card (11) located on the bottom surface of the lifting folding plate (10) is inserted into the anti-detachment groove (101). C. The outer end of the copper tube (2) is flared using an external flaring tool to form a flared section. The snap ring sleeve (4) is then fitted onto the outer edge of the flared section and secured with snap ring clips (5). The connection part of the polyamide connecting tube (1) is inserted into the flared section, so that the constricted part of the connection part and the inclined edge of the inner ring wall of the flared section come into contact and fit together. The solder ring (8) and the rubber fireproof expansion ring (9) from step B are located between the inner ring surfaces of the insertion part of the snap ring sleeve (4). At the same time, it is necessary to ensure that the outer surface of the solder ring (8) faces the through-hole (7). The outer surface of the flared section is heated by an oxyacetylene torch, so that the solder ring (8) melts and flows into the anti-detachment groove (101) to assist in fixing the card (11). Meanwhile, the rubber fireproof expansion ring (9) is subjected to After being indirectly heated by the oxyacetylene torch, thermal expansion occurs and pushes up the baffle plate (10), causing the molten solder ring (8) to pass into the through hole (7) and solidify with the inner ring wall of the flared part of the copper tube (2). Then, the solder is placed in the outer sealing solder layer (12) between the opening (6) and the outer surface of the connection between the polyamide connecting pipe (1) through the oxyacetylene torch. The outer sealing solder layer (12) seals the clamp (14), opening (6) and interface gap after cooling and solidification. At the same time, the outer side of the outer sealing solder layer (12) extends to the side surface of the heat insulation ring (13) in step A, and covers the exposed steel pipe layer (201) at the connection of the polyamide connecting pipe (1) with anti-corrosion coating, thus completing the installation and manufacturing of the connection of the polyamide connecting pipe (1) and the flared part of the copper tube (2).

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