CN117704163A

CN117704163A - Bell and spigot coated composite pipe and manufacturing method thereof

Info

Publication number: CN117704163A
Application number: CN202311858892.4A
Authority: CN
Inventors: 尹希伟; 肖和飞; 罗灿; 张新爱; 罗安明
Original assignee: Hunan Zhenhui Pipe Industry Co ltd
Current assignee: Hunan Zhenhui Pipe Industry Co ltd
Priority date: 2023-12-30
Filing date: 2023-12-30
Publication date: 2024-03-15

Abstract

The invention discloses a bell and spigot coated composite pipe and a manufacturing method thereof, the composite pipe comprises an inner pipe and an outer pipe, the inner pipe is sleeved in the outer pipe, the outer pipe comprises a socket part, a straight pipe part and a socket part which are sequentially connected, the inner pipe is made of corrosion-resistant metal materials, the inner wall of the socket part is provided with steps and/or grooves, one section of the inner pipe covers part of the inner wall of the socket part and part of the inner wall of the straight pipe part, and the other section of the inner pipe completely covers the socket part. The manufacturing method comprises the following steps: s1: treating the inner wall and the outer wall of the outer tube and manufacturing an inner tube; s2: the inner tube is sleeved and pressed on the outer tube. The inner pipe made of the corrosion-resistant material is used as the lining to cover the inner wall of the outer pipe, the end face of the spigot part of the composite pipe and the outer wall of the spigot part, so that the conveying environment is high in cleanliness, the composite pipe is good in corrosion resistance, simple to install, stable in operation and long in service life.

Description

Bell and spigot coated composite pipe and manufacturing method thereof

Technical Field

The invention belongs to the technical field of composite pipes, and particularly relates to a bell and spigot coated composite pipe and a manufacturing method thereof.

Background

Composite pipes are widely used in liquid delivery pipe network systems. When in use, the part of the pipe in contact with the liquid is required to have good corrosion resistance, so that the pipe is prevented from being corroded due to long-term contact with the liquid, and the quality of the conveyed liquid is prevented from being influenced. The existing composite pipe is generally characterized in that an outer layer is a metal pipe, an inner layer is a plastic pipe, and the inner layer and the outer layer are composited through a compositing process. Namely, the inner wall of the outer metal pipe is coated by the plastic pipe. When the inner plastic pipe is compounded, the inner surface is easy to be uneven or locally melt through when the temperature is too high, the resistance is increased due to the uneven inner surface when the liquid is conveyed, the product is scrapped due to the local melt through of the inner plastic pipe, the production cost is increased, the thermal expansion coefficient of the inner plastic pipe is large, the shrinkage at low temperature is large, the internal stress of the inner plastic pipe which is mutually stripped with the outer metal pipe is large, and the risk of layering of the lining exists when the inner plastic pipe is used for a long time. The structure of the existing composite pipe is a socket structure, one end of the metal pipe is a socket end, and the other end of the metal pipe is a socket end. When the pipe network is installed, a plurality of composite pipes are connected in sequence, and the socket end of one composite pipe is inserted into the socket end of the adjacent composite pipe. However, the mode does not enable the anti-corrosion coating of the pipe to form a whole, liquid in the pipeline can permeate into the inner wall of the metal pipe through gaps among different materials after long-term flushing in the use process, so that anti-corrosion failure and corrosion of the pipe wall are caused, the service life of the pipeline is influenced, and pollution is caused to the liquid conveyed in the pipeline.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a bell and spigot coated composite pipe and a manufacturing method thereof, wherein an inner pipe made of corrosion-resistant materials is used as a lining to cover the inner wall of an outer pipe, the end face of a spigot part of the composite pipe and the outer wall of the spigot part, so that the conveying environment is high in cleanliness, the composite pipe is good in corrosion resistance, simple to install, stable in operation and long in service life.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

the utility model provides a bell and spigot coated composite pipe, includes inner tube and outer tube, and the inner tube cup joints in the outer tube, and the outer tube is including socket, straight tube portion and the socket that connects gradually, and the inner tube adopts corrosion-resistant metal material to make, and the inner wall of socket is equipped with ladder and/or recess, and the inner wall of part socket and the inner wall of straight tube portion are covered to one section of inner tube, and the other section of inner tube cladding socket completely.

As a further improvement of the above technical scheme:

preferably, the inner tube comprises an inner sleeve and a socket sleeve, a section of the inner tube covering the outer wall of the socket part is the socket sleeve, and a section of the inner tube covering the inner wall of the outer tube is the inner sleeve.

Preferably, the inner sleeve and the socket sleeve are integral.

More preferably, the socket sleeve is formed by spinning one end of the inner tube outwards.

More preferably, the socket sleeve and the inner sleeve are welded together.

Preferably, the welding position of the socket sleeve and the inner sleeve is positioned on the end face of the socket part, and the inner tube area covering the end face of the socket part is formed by welding after flanging the socket sleeve and/or flanging the inner sleeve.

Preferably, the thickness of the inner sleeve is not less than 0.1mm.

Preferably, the straight pipe portion and the socket portion are integrally formed as a pipe body by welding a composite plate of stainless steel and carbon steel.

Preferably, when two adjacent composite pipes are connected, the socket part of one composite pipe is inserted into the socket part of the adjacent composite pipe and is sealed by the sealing ring, the outer ring of the sealing ring contacts the inner wall of the inner pipe of the socket part of the one composite pipe, and the inner ring of the sealing ring contacts the outer wall of the socket sleeve on the outer wall of the socket part of the adjacent composite pipe.

More preferably, the sealing ring is provided with at least one sealing ring, and the sealing ring is arranged in the inner wall groove of the bearing part or limited by the limiting piece.

A method of manufacturing a socket-coated composite pipe for use in manufacturing said composite pipe, comprising the steps of:

step S1: treating the inner wall and the outer wall of the outer tube and manufacturing an inner tube;

step S2: the inner tube is sleeved and pressed on the outer tube.

In step S2, the inner sleeve is tightly pressed on the inner wall of the outer tube through spinning forming or hydraulic forming.

In the step S3, the socket sleeve is obtained by spin forming one end of the inner pipe.

Preferably, in step S1, when the inner tube is manufactured, the inner sleeve and the socket sleeve are manufactured respectively, the socket sleeve is sleeved on the outer wall of the socket part, and between step S3 and step S4, the inner sleeve and the socket sleeve are welded, and the welding position is positioned on the end face of one end of the socket part of the composite tube.

The beneficial effects of the invention are as follows:

(1) The inner pipe of corrosion-resistant material covers outer pipe inner wall, socket portion terminal surface and socket portion outer wall, with the outer pipe with the interior circulation of compound intraductal liquid keeps apart completely, effectively prevents the outer tube to take place the corrosion, plays better anticorrosive effect, has improved the life of tubular product, avoids the corrosion pollution quality of water of outer tube, has improved liquid conveying performance.

(2) Compared with the plastic pipe lining, the inner pipe made of the corrosion-resistant metal material has the advantages that the surface smoothness of the inner surface of the composite pipe is improved, the thickness of the lining is smaller, the water delivery efficiency of the pipeline is improved, and the operation energy consumption is reduced.

(3) Compared with the inner liner of the plastic pipe, the inner liner of the plastic pipe has the advantages that the inner liner is made of corrosion-resistant metal, the internal stress of mutual stripping generated between the inner pipe and the outer pipe due to inconsistent expansion coefficients of the materials is greatly reduced, and layering and deformation of the inner liner are not easy to occur.

(4) Compared with the plastic pipe lining, the inner pipe made of the corrosion-resistant metal can be applied to conveying high-temperature liquid medium, and the lining cannot be damaged when the pipe is affected by high temperature such as external fire and the like.

(5) During installation, the socket part of the composite pipe is inserted into the socket part of the adjacent composite pipe and is sealed by the sealing ring, the outer ring of the sealing ring is tightly pressed against the inner pipe inner wall of the socket part, the inner ring is tightly pressed against the socket sleeve of the outer wall of the socket part, the inner pipe serving as the lining is prevented from falling off, and meanwhile, the water flow is prevented from directly impacting the corrosion-resistant port of the lining to cause delamination of the composite pipe.

(6) After two adjacent composite pipes are connected, a gap exists between the end face of the socket part of one composite pipe and the end face of the straight pipe part of the composite pipe adjacent to the end face, liquid can infiltrate into and contact the outer wall of the socket part through the gap, at the moment, the socket sleeve made of corrosion-resistant materials can play a role in corrosion prevention, meanwhile, the inner ring of the sealing ring is tightly pressed against the outer wall of the socket part, the straight pipe part and the socket part are completely separated from liquid, and the straight pipe part and the socket part are prevented from being contacted with the liquid to be corroded.

(7) The socket sleeve is connected with the inner sleeve through welding, the welding point is arranged on the end face of the socket part, the manufacturing and the processing are convenient, and the welding line has no influence on the installation of the pipe.

(8) The pipe body can be formed by welding a stainless steel and carbon steel composite plate, and the inner lining is corrosion-resistant, the processing technology is simple, and the pipe strength is high.

Drawings

Fig. 1 is a schematic structural view of the first embodiment of the present invention when the outer wall of the straight pipe portion is flush with the outer wall of the socket.

Fig. 2 is a schematic view of the structure when the thickness of the straight pipe portion and the thickness of the socket portion are equal in the first embodiment of the present invention.

Fig. 3 is a schematic diagram showing connection between two adjacent composite pipes with the outer wall of the straight pipe portion and the outer wall of the socket sleeve being flush.

Fig. 4 is a schematic diagram of connection between two adjacent composite pipes with equal thicknesses of the straight pipe portion and the socket portion according to the first embodiment of the present invention.

Fig. 5 is a schematic structural view of the second embodiment of the present invention when the outer wall of the straight pipe portion is flush with the outer wall of the socket.

Fig. 6 is a schematic view of the structure when the thickness of the straight pipe portion and the thickness of the socket portion are equal in the second embodiment of the present invention.

Fig. 7 is a schematic diagram of connection between two adjacent composite pipes with the outer wall of the straight pipe portion and the outer wall of the socket sleeve flush in the second embodiment of the present invention.

Fig. 8 is a schematic diagram of connection between two adjacent composite pipes with equal thicknesses of the straight pipe portion and the socket portion according to the second embodiment of the present invention.

Detailed Description

The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.

Spatially relative terms, such as "above … …," "above … …," "upper surface at … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial location relative to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or structures would then be oriented "below" or "beneath" the other devices or structures. Thus, the exemplary term "above … …" may include both orientations of "above … …" and "below … …". The device may also be positioned in other different ways (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Example 1

A bell and spigot coated composite pipe, as shown in figures 1 to 4, comprises an inner pipe 2 and an outer pipe 1.

The outer tube 1 includes a socket portion 11, a straight tube portion 12, and a spigot portion 13, which are sequentially connected along the axial direction thereof, that is, the socket portion 11, the straight tube portion 12, and the spigot portion 13 are concentric. Both the straight pipe portion 12 and the socket portion 13 are cylindrical, and one end of the socket portion 13 remote from the straight pipe portion 12 is provided with a chamfer in the circumferential direction. The inner surface of the bearing part 11 is provided with steps and/or grooves, that is, the bearing part 11 can be regarded as being formed by sequentially connecting a plurality of tubular structures with different inner diameters.

The outer tube 1 is made of metal, preferably ductile iron or carbon steel. The socket portion 11, the straight pipe portion 12 and the spigot portion 13 are integrally cast or separately manufactured and welded, and the inside diameter of the spigot portion 13 is equal to the inside diameter of the straight pipe portion 12.

The inner tube 2 is sleeved in the outer tube 1, and the inner tube 2 is made of a material with a corrosion-resistant function, including but not limited to stainless steel, titanium, composite materials, preferably stainless steel. One end of the inner tube 2 covers the inner wall of the outer tube 1, and the other end covers the end face of the socket portion 13 and the outer wall of the socket portion 13. Specifically, the inner tube 2 includes an inner sleeve 22 and a socket sleeve 21, stainless steel covering the outer wall of the socket portion 13 is the socket sleeve 21, stainless steel covering the inner wall of the outer tube 1 is the inner sleeve 22, and the inner sleeve 22 and the socket sleeve 21 are integrated. The inner tube 2 has no holes and is a continuous medium, and can completely cover most of the inner wall of the socket part 11, all of the inner wall of the straight tube part 12, all of the inner wall of the socket part 13, the end face of the socket part 13 and the outer wall of the socket part 13.

The thickness of the socket sleeve 21 may be greater than, less than, or equal to the thickness of the inner sleeve 22.

The socket sleeve 21 can be formed by spinning one end of the inner tube 2 outwards; or the socket 21 and the inner sleeve 22 are welded together, preferably at the end face of the composite pipe socket 13. Specifically, the stainless steel covering the end face of the socket portion 13 is formed by welding after the socket sleeve 21 is turned over and/or the inner sleeve 22 is turned over.

Obviously, the inner sleeve 22 is the inner lining of the composite tube.

As shown in fig. 2, the thickness of the socket portion 13 is equal to the thickness of the straight tube portion 12, and after the completion of the manufacturing, the socket sleeve 21 protrudes out of the outer wall of the straight tube portion 12. Or as shown in fig. 1, the sum of the thickness of the socket part 13 and the thickness of the socket sleeve 21 is equal to the thickness of the straight pipe part 12, so that after the manufacture is finished, the outer wall of the straight pipe part 12 is flush with the outer wall of the socket sleeve 21, the appearance is more attractive, and the socket part 13 is not easy to damage during the conveying process.

As shown in fig. 1 and 2, the socket 11 includes a seal ring stopper 111, a seal ring accommodating end 112, a seal ring stopper protrusion 113, a first step 114, and a second step 115 in this order from the end far from the straight pipe 12 toward the end near the straight pipe 12. The inner diameter of the seal ring limiting end 111 is smaller than the inner diameter of the seal ring accommodating end 112, the inner diameter of the seal ring limiting protrusion 113 is larger than the inner diameter of the seal ring limiting end 111 and smaller than the inner diameter of the seal ring accommodating end 112, and the inner diameter of the first step 114 is basically equal to the inner diameter of the seal ring accommodating end 112. The inner wall of the first step 114 is a cylindrical wall. The inner wall of the second step 115 is the outer surface of the truncated cone, that is, the inner diameter of the second step 115 gradually increases from the first step 114 toward the straight tube portion 12, which corresponds to a flare. Preferably, the maximum inner diameter of the second step 115 is smaller than the inner diameter of the first step 114. The minimum inner diameter of the second step 115 is larger than the inner diameter of the straight tube portion 12. Thus, the straight tube portion 12 forms a third step at one end thereof adjacent to the second step 115.

The inner wall flare of the second step 115 is provided to provide a deflection angle to the adjacent composite pipe to which it is connected, i.e., to allow the center line of one composite pipe and the center line of the adjacent composite pipe to which it is connected to be in an intersecting state, not in a coincident state, in order to allow a certain installation error, facilitating practical operation.

Preferably, the inner tube 2 covers the inner wall of the first step 114 and the inner wall of the second step 115, and the inner tube 2 does not cover the inner wall of the seal ring limiting end 111, the inner wall of the seal ring accommodating end 112 and the inner wall of the seal ring limiting protrusion 113.

In this embodiment, the outer diameter of the inner tube 2 is slightly smaller than the inner diameter of the outer tube 1, and the thickness of the inner sleeve 22 is not smaller than 0.1mm.

The main function of the inner tube 2 is corrosion prevention, the thickness is not too large, and a large number of welding tests show that under the condition of the optical fiber laser welding process, the welding seam with high welding strength and small deformation can be obtained by the stainless steel plate under the minimum wall thickness of 0.1mm.

Based on the above structure, when two adjacent composite pipes are connected, as shown in fig. 3 and 4, the spigot portion 13 of one composite pipe is inserted into the socket portion 11 of the adjacent composite pipe and sealed by the seal ring 3, the outer ring of the seal ring 3 contacts the inner wall of the inner pipe 2 at the socket portion 11 of one composite pipe, and the inner ring of the seal ring 3 contacts the outer wall of the spigot sleeve 21 on the outer wall of the spigot portion 13 of the adjacent composite pipe. Preferably, one end face of the sealing ring 3 contacts with the end face of the sealing ring limiting end 111, a part of the sealing ring 3 is accommodated on the sealing ring accommodating end 112, the sealing ring limiting protrusion 113 is clamped into the middle of the sealing ring 3, and the other part of the sealing ring 3 is located on the first step 114. Meanwhile, a gap exists between the end face of one end of the composite pipe plug 13 and the end face of the straight pipe 12 of the adjacent composite pipe, and the gap also exists to allow the deflection angle when the two adjacent composite pipes are installed.

From the top, the length of socket portion 13 is greater than the length of bellmouth portion 11 to when two adjacent pipes socket connection, the inner circle and the outer lane of sealing washer 3 can both contact the stainless steel, avoid straight tube portion 12 part to stretch into between sealing washer 3 and the socket portion 13 terminal surface, lead to the straight tube portion 12 of this part to contact the liquid and take place the corrosion. Meanwhile, the inner pipe 2 on the end face of the composite pipe prevents the liquid in the pipeline from contacting with the end face of the socket part 13, and the problem of delamination and corrosion of the composite pipe is caused by the tension of water.

A method of manufacturing a socket-coated composite tube for use in manufacturing the composite tube, comprising the steps of:

step S1: the inner wall and the outer wall of the outer tube 1 are treated, an inner sleeve 22 is manufactured, and a socket sleeve 21 is manufactured.

In this step, the method for treating the inner wall and the outer wall of the outer tube 1 is to polish the inner wall of the outer tube 1 first, and then to sand blast or throw the inner wall and the outer wall. And (3) polishing the inner wall of the outer tube 1 made of the nodular cast iron by using an inner grinder, polishing the inner wall of the tube to be smooth, and removing surface oxide skin, scum, rust and the like. Or after the inner wall is polished and leveled, cleaning the inner wall of the pipe by using a laser cleaning machine, and deeply removing oxide skin and rust on the inner wall of the pipe. During sand blasting or shot blasting, dust, oxide skin and rust on the inner wall and the outer wall of the pipe are removed, and sand is blasted into frosted surfaces.

The inner sleeve 22 is made by the steps of:

s11: the stainless steel sheet is processed into a ring shape or a cylinder shape with a very thin thickness, and the rolling is completed. In this step, the rolling is performed by a rolling machine.

S12: cutting the rolled stainless steel sheet, and welding the cut stainless steel sheet into a cylinder shape. In this step, if the single round is obtained in step S11, straight seam welding is performed by using an argon arc welder or a laser welder, and the weld extends from one end to the other end of the inner sleeve 22. If the step S11 is performed with a plurality of spirally-connected convolutions, the spirally-connected convolutions are sequentially welded by a spiral seam welder to form a cylindrical shape with a very thin thickness.

Preferably, the length of the stainless steel round tube obtained in the step S12 is greater than the length of the inner sleeve 22 of the composite tube which is finally processed. Specifically, the length of the stainless steel round tube obtained in step S12 is greater than the sum of the length of the socket portion 11, the length of the straight tube portion 12, and the length of the spigot portion 13.

The step of manufacturing the socket sleeve 21 is the same as the step of manufacturing the inner sleeve 22. The length of the socket 21 is greater than the length of the socket portion 13.

Preferably, the thickness of the inner sleeve 22 is not less than 0.1mm.

Step S2: and (3) penetrating the pipe, sleeving and pressing the inner sleeve 22 in the outer pipe 1. In the step, the sleeve is firstly sleeved by a manual or pipe penetrating machine. Then, the inner sleeve 22 is pressed against the outer tube 1 again.

This step can be accomplished by spin forming or hydroforming when the inner sleeve 22 is compressed against the outer tube 1. During spinning, the socket part 13, the straight pipe part 12 and the inner sleeve 22 of the bearing part 11 are respectively spun and formed by utilizing a pipe spinning machine, and during spinning of the bearing part 11, the inner sleeve 22 made of stainless steel is tightly pressed on the outer pipe 1 by utilizing the pipe orifice spinning machine from inside to outside. During hydraulic forming, the two ends of the inner sleeve 22 made of stainless steel penetrating into the outer tube 1 are sealed by a tube hydraulic press, and water is injected into the tube to pressurize, so that the inner sleeve 22 is tightly pressed on the outer tube 1.

Step S3: the socket 21 is tightened against the socket portion 13. The socket portion 13 is expanded in diameter by the expanding machine, and the socket sleeve 21 is fitted tightly on the socket portion 13.

Step S4: the inner sleeve 22 and the socket sleeve 21 are welded, and the welding position is positioned on the end face of one end of the socket part 13 of the composite pipe. In this step, first, the inner sleeve 22 and/or the socket sleeve 21 at one end of the socket portion 13 is spun by a tube orifice spinning machine, so that the inner sleeve 22 and/or the socket sleeve 21 covers the end face at one end of the socket portion 13 of the composite tube. Then, redundant burrs are trimmed, and subsequent welding is facilitated. Finally, the inner sleeve 22 and the socket sleeve 21 are welded together, and the welded part is positioned on the end face of one end of the socket part 13 of the composite pipe. Preferably, the socket 21 and the socket 13 are welded together, and the welded part is located on the outer wall of the socket 13, and is circumferentially located along the outer wall of the socket 13.

After the steps are completed, the outer wall of the pipe is sprayed with paint or plastic or other modes for external anti-corrosion treatment.

Example two

The present embodiment differs from the first embodiment in the structure of the socket 11 and the number of seal rings 3.

As shown in fig. 5 to 8, the socket portion 11 includes a seal ring mounting portion 116 and a transition portion 117 which are integrally connected and arranged in this order from the direction away from the straight pipe portion 12 toward the direction toward the straight pipe portion 12. The sealing ring installation part 116 is of a cylindrical structure, at least two annular grooves which are arranged at intervals are formed in the inner wall of the sealing ring installation part 116, the annular grooves and the composite pipe are coaxial, and the grooves are sealing ring installation grooves 118. The transition portion 117 includes a cylindrical portion and a circular truncated cone portion, and the seal ring mounting portion 116, the cylindrical portion, the circular truncated cone portion, and the straight tube portion 12 are connected in this order. The inner diameter of the cylindrical portion is larger than the inner diameter of the straight tube portion 12.

In this embodiment, two seal ring mounting grooves 118 are provided on the inner wall of the socket 11. The inner tube 2 covers the inner wall of the cylindrical portion of the socket portion 11, the inner wall of the truncated cone portion, and the inner wall of one seal ring mounting groove 118 near the cylindrical portion, and the inner tube 2 does not cover the inner wall of one seal ring mounting groove 118 far from the cylindrical portion.

With the above configuration, as shown in fig. 7 and 8, when two adjacent composite pipes are connected, the socket portion 13 of one composite pipe is inserted into the socket portion 11 of the adjacent composite pipe and sealed by at least two seal rings 3, and each seal ring 3 is mounted in each seal ring mounting groove 118. Similarly, the inner ring of at least one sealing ring 3 contacts the outer wall of the socket sleeve 21 on the outer wall of the socket part 13 of one composite pipe, and the outer ring of at least one sealing ring 3 contacts the inner wall of the inner pipe 2 at the position of the socket part 11 of the adjacent composite pipe. Compared with the first embodiment, the socket structure of the first embodiment is simpler, and the processing and manufacturing are easier.

Example III

The difference between this embodiment and the first or second embodiment is the manufacturing method of the composite pipe, in this embodiment, the manufacturing method includes the steps of:

step S1: a pipe body, a socket portion 11, a portion of the inner pipe 2 covering the socket portion 11, and a socket 21 are manufactured, specifically, the pipe body refers to the straight pipe portion 12 and the socket portion 13. The pipe body comprises a pipe body of the outer pipe 1 and a pipe body of the inner pipe 2.

In this example, the raw material used was a composite plate of stainless steel and carbon steel, stainless steel was used as the inner tube 2, and carbon steel was used as the outer tube 1.

When the pipe body is manufactured, the pipe body of the inner pipe 2 is welded firstly, and then the pipe body of the outer pipe 1 is welded, and the welding can be performed through straight seam welding pipe equipment and spiral seam welding pipe equipment. When the straight seam welding pipe equipment is used for welding, the stainless steel layer of the composite board is firstly welded in a straight seam mode to form a circular pipe, and then the carbon steel layer of the composite board is welded in a straight seam mode to form a pipe body.

When the spiral seam welding pipe equipment is used for welding, a plurality of spirally connected coiled circles are sequentially welded to form a cylinder, namely the pipe body. During welding, the inner stainless steel layer is welded first, and then the outer carbon steel layer is welded.

When the socket 11 is manufactured, the blast furnace molten iron is cast into a socket 11 blank made of cast steel by a casting device.

When the inner tube 2 covering the socket 11 is manufactured, the stainless steel is welded by straight seam welding by an argon arc welding machine or a laser welding machine to form a circular tube shape, and the length of the circular tube is longer than that of the pipe blank of the socket 11.

Step S2: the part of the inner tube 2 covering the socket part 11 prepared in the step S1 is sleeved into the pipe blank of the socket part 11 and is tightly attached to the inner wall of the socket part 11.

In this step, the inner tube 2 portion covering the socket 11 is made to abut against the inner wall of the socket 11 by spinning with a spinning machine, or the inner tube 2 portion covering the socket 11 is made to abut against the inner wall of the socket 11 by expanding the diameter of the inner tube 2 portion with an expanding die with an expanding machine. Then, the part of the stainless steel pipe extending out of the pipe blank of the bearing part 11 lining the bearing mouth is trimmed.

Step S3: and welding the socket part 11. And (2) welding the socket part 11 with the stainless steel sleeved inside obtained in the step (S2) and the pipe body obtained in the step (S1) together, wherein the welding is performed twice, and firstly, the stainless steel layer of the inner layer is welded, and then, the carbon steel layer is welded.

The socket 21 is manufactured in the same way as in the first embodiment.

Step S4: the socket 21 is fitted over the socket portion 13.

Step S5: the inner sleeve 22 and the socket sleeve 21 are welded, and the welding position is positioned on the end face of one end of the socket part 13 of the composite pipe. This step is the same as in example one.

The manufacturing method of the embodiment does not need spinning or hydraulic forming of the pipe body, equipment investment is small, the process is simple, and the bonding strength between the metal pipe and the stainless steel is high.

Example IV

The present embodiment differs from the first embodiment or the second embodiment in the method of forming the socket 21.

In this embodiment, instead of separately manufacturing the socket sleeve 21 and the inner sleeve 22, a tubular inner tube 2 is integrally manufactured, and after the inner tube 2 is sleeved into the outer tube 1, one end of the inner tube 2 extends beyond the end face of the socket portion 13, and the part of the inner tube 2 extending beyond the end face of the socket portion 13 is turned over by spin forming and is pressed on the outer wall of the socket portion 13, so as to form the socket sleeve 21.

Finally, what is necessary here is: the above embodiments are only for further detailed description of the technical solutions of the present invention, and should not be construed as limiting the scope of the present invention, and some insubstantial modifications and adjustments made by those skilled in the art from the above description of the present invention are all within the scope of the present invention.

Claims

1. The utility model provides a bell and spigot coated composite pipe, a serial communication port, including inner tube (2) and outer tube (1), inner tube (2) cup joint in outer tube (1), outer tube (1) are including bellmouth portion (11), straight tube portion (12) and socket portion (13) that connect gradually, inner tube (2) adopt corrosion-resistant metal material to make, the inner wall of bellmouth portion (11) is equipped with ladder and/or recess, the inner wall of one section cover part bellmouth portion (11) of inner tube (2) and the inner wall of straight tube portion (12), the other section of inner tube (2) cladding socket portion (13) completely.

2. The composite tube of claim 1, wherein: the inner tube (2) comprises an inner sleeve (22) and a socket sleeve (21), a section of the inner tube (2) covering the outer wall of the socket part (13) is the socket sleeve (21), and a section of the inner tube (2) covering the inner wall of the outer tube (1) is the inner sleeve (22).

3. The composite tube of claim 2, wherein: the inner sleeve (22) and the socket sleeve (21) are integrated.

4. A composite tube according to claim 3, wherein: the socket sleeve (21) is formed by spinning one end of the inner tube (2) outwards.

5. A composite tube according to claim 3, wherein: the socket sleeve (21) and the inner sleeve (22) are welded together.

6. The composite tube of claim 5, wherein: the welding part of the socket sleeve (21) and the inner sleeve (22) is positioned on the end face of the socket part (13), and the area of the inner tube (2) covering the end face of the socket part (13) is formed by welding after flanging the socket sleeve (21) and/or flanging the inner sleeve (22).

7. The composite tube of claim 2, wherein: the thickness of the inner sleeve (22) is not less than 0.1mm.

8. The composite tube of claim 2, wherein: the straight pipe part (12) and the socket part (13) are integrally formed by welding a stainless steel and carbon steel composite plate as a pipe body.

9. The composite tube of claim 1, wherein: when two adjacent composite pipes are connected, the socket part (13) of one composite pipe is inserted into the bell mouth part (11) of the adjacent composite pipe and is sealed by the sealing ring (3), the outer ring of the sealing ring (3) contacts the inner wall of the inner pipe (2) of the bell mouth part (11) of the composite pipe, and the inner ring of the sealing ring (3) contacts the outer wall of the socket sleeve (21) on the outer wall of the socket part (13) of the adjacent composite pipe.

10. The composite tube of claim 9, wherein: the sealing ring (3) is provided with at least one, and the sealing ring (3) is arranged in the inner wall groove of the bearing part (11) or is limited by a limiting piece.

11. A method of manufacturing a socket-coated composite pipe for use in manufacturing a composite pipe according to any one of claims 1 to 10, characterized in that: the method comprises the following steps:

step S1: treating the inner wall and the outer wall of the outer tube (1) and manufacturing the inner tube (2);

step S2: the inner tube (2) is sleeved and pressed on the outer tube (1).

12. The manufacturing method according to claim 11, characterized in that: in the step S2, the inner sleeve (22) is tightly pressed on the inner wall of the outer tube (1) through spinning forming or hydraulic forming.

13. The manufacturing method according to claim 11, characterized in that: in the step S3, the socket sleeve (21) is obtained by spin forming one end of the inner tube (2).

14. The manufacturing method according to claim 11, characterized in that: in the step S1, when the inner pipe (2) is manufactured, an inner sleeve (22) and a socket sleeve (21) are manufactured respectively, the socket sleeve (21) is sleeved on the outer wall of the socket part (13), and between the step S3 and the step S4, the inner sleeve (22) and the socket sleeve (21) are welded, and the welding position is positioned on the end face of one end of the socket part (13) of the composite pipe.