CN117759791A - Socket-type multi-layer pipe with corrosion-resistant metal lining and manufacturing method thereof - Google Patents

Abstract

The invention discloses a corrosion-resistant metal-lined socket-type multi-layer pipe and a manufacturing method thereof. It belongs to the technical field of pipes. The pipe includes an inner pipe, an intermediate layer and an outer pipe that are connected in sequence from the inside to the outside. The inner wall is provided with steps or grooves, and the outer tube includes a socket portion, a straight tube portion, and a spigot portion connected in sequence. At least one layer of the inner tube and the outer tube is made of metal material. The manufacturing method includes the following steps: S1: processing the outer tube, making the inner tube and the middle layer; S2: arranging the inner tube, the middle layer and the outer tube in sequence from the inside to the outside; S3: pressing the inner tube and the middle layer onto the outer tube ;S4: Composite; When the material of the middle layer is plastic or rubber, there is no step S4. The inner pipe made of stainless steel in the present invention is used as the lining to prevent the outer pipe from rusting and polluting the water quality. The middle layer completely separates the inner pipe and the outer pipe to prevent electrochemical corrosion of the inner pipe. A lining ring and a sealing gasket are provided at the end of the pipe to prevent each layer from being corroded. The end of the bonding surface between the materials comes into contact with water, polluting the water and the lining is washed away.

Description

Corrosion-resistant metal-lined socket-type multi-layer pipe and manufacturing method thereof

Technical field

The invention belongs to the technical field of pipes, and is specifically a socket-type multi-layer pipe lined with corrosion-resistant metal and a manufacturing method thereof.

Background technique

Composite pipe is a widely used pipe material, often used in liquid transportation pipe network systems. It is generally a socket structure, including an outer metal pipe and an inner plastic pipe, that is, the plastic pipe serves as the lining, and one end of the metal pipe is a socket. One end and the other end are the socket ends. During installation, multiple 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 thermal expansion coefficient of the plastic pipe lining is very different from that of the metal outer pipe. Due to temperature changes, the inner pipe and the outer pipe will produce a certain amount of mutually separated internal stress, which will cause the lining to delaminate. In addition, liquid easily penetrates from the pipe end, causing corrosion of the outer pipe and contaminating the transported liquid, and causing peeling and delamination of the end surfaces of each layer, and the inner layer will be washed away under long-term erosion.

Contents of the invention

In view of the above-mentioned problems existing in the prior art, the purpose of the present invention is to provide a socket-type multi-layer pipe with a corrosion-resistant metal lining and a manufacturing method thereof. The inner pipe made of corrosion-resistant metal is used as the lining to avoid corrosion and contamination of the outer pipe. Water quality, the thickness of the lining is small, which improves the water transmission efficiency of the pipeline and reduces the operating energy consumption. The middle layer is made of insulating hot melt glue or plastic or rubber, which completely separates the inner pipe from the outer pipe and prevents the outer pipe from being separated from the inner pipe. Contact causes electrochemical corrosion of the inner tube, and at the same time eliminates the shortcomings of using ordinary liquid glue in the middle layer. When the middle layer is hot melt glue, the hot melt glue bonds the inner and outer layers together. When the middle layer is rubber, the elasticity of the rubber makes The metal outer pipe and the corrosion-resistant metal inner pipe form mutual elastic forces, which have good sealing performance on the inner wall of the metal pipe. The end of the pipe is equipped with a corrosion-resistant metal lining ring and a rubber sealing gasket to prevent the ends of the bonding surfaces between the layers of materials from contacting water. Water contamination caused by contact and lining washed away.

In order to achieve the above objects, the technical solutions adopted by the present invention are:

A corrosion-resistant metal-lined socket-type multi-layer pipe, including an inner pipe, an intermediate layer and an outer pipe that are connected in sequence from the inside to the outside. The inner wall of the socket is provided with steps and/or grooves. The inner pipe, the middle layer The layer and the outer pipe are bonded or compressed to form the pipe. The outer pipe includes a socket part, a straight pipe part and a spigot part connected in sequence. At least one layer of the inner pipe and the outer pipe is made of metal material.

As a further improvement of the above technical solution:

Preferably, the material of the outer tube is metal.

Preferably, the material of the middle layer is non-metallic material.

More preferably, the material of the middle layer is hot melt adhesive.

More preferably, the material of the middle layer is plastic.

More preferably, the material of the middle layer is rubber.

The inner tube is made of corrosion-resistant material.

The thickness of the middle layer is not less than 0.2mm, and the thickness of the inner tube is not less than 0.1mm.

At one end of the socket part, the end surface of the inner tube, the end surface of the middle layer and the end surface of the straight tube part are flush. At the end of the socket part, the end surface of the inner tube, the end surface of the middle layer and the end surface of the socket part are flush.

Each end of the pipe is provided with a sealing gasket and a lining ring. At one end of the socket, the sealing gasket covers the end face of the straight pipe part, the end face of the middle layer, the end face of the inner pipe and the inner wall of one end of the inner pipe. At one end of the socket part, the sealing gasket covers the end face of the socket part, the end face of the middle layer, the end face of the inner tube and the inner wall of the other end of the inner tube. The lining ring presses the sealing gasket tightly. When in use, the lining ring and sealing gasket at one end of the socket part A full seal is formed on the end face of the socket part, and the lining ring and sealing gasket at one end of the socket part are fully sealed on the end face of the straight pipe part.

The gasket includes a gasket press and a gasket flange. The gasket press is cylindrical and the gasket flange is annular. The lining ring includes a liner ring press and a lining flange. The liner ring press and the lining are The ring flange is a whole, the lining ring flange is cylindrical, and the lining ring flange is annular. The lining ring flange presses the sealing gasket tightly, and the lining ring flange flanges the sealing gasket tightly.

The length of the edge of the lining ring shall not be less than 20mm.

A method of manufacturing a corrosion-resistant metal-lined socket-type multi-layer pipe, used to manufacture the pipe, including the following steps:

Step S1: Process the outer tube, make the inner tube and the middle layer;

Step S2: Arrange the inner tube, middle layer and outer tube in sequence from inside to outside;

Step S3: Press the inner tube and the middle layer tightly onto the outer tube;

Step S4: compound;

When the material of the middle layer is plastic or rubber, there is no step S4.

The manufacturing method also includes step S5: lining rings, inserting a sealing gasket and lining rings at each end of the pipe.

When the middle layer is made of hot melt glue or plastic, in step S1, a tubular middle layer can be made separately, and in step S2, the middle layer can be put outside the inner tube and then put into the outer tube as a whole; or the powdery hot melt can be first Melt glue or plastic is rotomolded or spray-molded on the inner wall of the outer pipe, and then the inner pipe is inserted into the outer pipe in step S2; or powdered hot melt glue or plastic is rotomolded or spray-molded on the outer wall of the inner pipe first, and then In step S2, insert the inner tube into the outer tube.

The beneficial effects of the present invention are:

(1) The inner pipe made of corrosion-resistant metal is used as the lining to completely isolate the outer pipe from the liquid circulating in the pipe, effectively preventing the outer pipe from rusting, playing a good anti-corrosion role, extending the service life of the pipe, and preventing The corrosion of the outer pipe pollutes the water quality and improves the liquid transportation performance.

(2) The inner pipe made of corrosion-resistant metal is used as the inner lining. Compared with the plastic pipe lining, it eliminates the inner surface wrinkles and uneven unevenness defects caused by the thermal melting of the lining plastic during compounding, and improves the inner surface of the pipe. The flatness and smaller lining thickness improve the efficiency of pipeline water delivery and reduce operating energy consumption.

(3) The inner pipe made of corrosion-resistant metal is used as the lining. Compared with the plastic pipe lining, the pipe can be used to transport high-temperature liquid media.

(4) The middle layer is made of insulating hot melt adhesive, plastic or rubber, which completely separates the inner tube and the outer tube, preventing the outer tube from contacting the inner tube and causing electrochemical corrosion of the inner tube. At the same time, it eliminates the use of ordinary liquids in the middle layer. The glue layer is uneven due to the flow of glue, and the corrosion-resistant metal lining and the outer metal pipe are not bonded and are in direct contact with each other to cause electrochemical corrosion. It also overcomes the problems of ordinary glue that is easy to age and has poor insulation.

(5) When the middle layer is made of hot melt adhesive, the hot melt glue will bond the inner and outer layers into one body, preventing the negative pressure in the pipeline from causing delamination of the lining. When the middle layer is made of rubber, the elasticity of the rubber will make the metal outer pipe and corrosion-resistant The metal inner tube forms mutual elastic force and has good sealing performance on the inner wall of the metal tube, which can prevent the liquid from contacting the inner wall of the metal outer tube and causing corrosion of the tube wall.

(6) Corrosion-resistant metal lining rings and rubber seals are installed at the ends of the pipes to prevent the ends of the bonding surfaces between the layers of materials from contacting water and peeling due to the tension of the water, and to prevent the inner wall of the metal outer pipe from being corroded and peeled off, causing water pollution. ; The lining ring and sealing gasket play a fixed role in the inner pipe. When the seal fails and the lining is completely delaminated, it can still protect the lining from being washed away by water flow; the setting of the lining ring and sealing gasket strengthens the pipe. The ring stiffness of the port makes the socket not easily deformed, which facilitates the installation of pipes, improves the uniform sealing effect of the gasket and the sealing ring at the connection of the two pipes, and reduces pipe leakage.

Description of the drawings

Figure 1 is a schematic structural diagram of the pipe without sealing gaskets and lining rings at both ends of the present invention.

Figure 2 is a schematic structural diagram of the pipe according to the present invention when there are sealing gaskets and lining rings at both ends.

FIG. 3 is an enlarged schematic diagram of B in FIG. 2 .

Figure 4 is an enlarged schematic diagram of point A in Figure 2 .

Detailed ways

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

For the convenience of description, spatially relative terms can be used here, such as "on...", "on...", "on the upper surface of...", "above", etc., to describe what is shown in the figure. The spatial relationship between one device or feature and other devices or features. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a feature in the figure is turned upside down, then one feature described as "above" or "on top of" other features or features would then be oriented "below" or "below" the other features or features. under other devices or structures". Thus, the exemplary term "over" may include both orientations "above" and "below." The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

A corrosion-resistant metal-lined socket-type multi-layer pipe, which is mainly used for water and corrosive liquids. As shown in Figures 1 and 2, it includes an inner tube 2, an intermediate layer 3 and an outer tube 1 that are sleeved in sequence from the inside to the outside.

The outer tube 1 is made of metal, preferably ductile iron or carbon steel. The outer tube 1 includes a socket portion 11, a straight tube portion 12 and a spigot portion 13 connected in sequence along its axial direction. The three are integrally cast, or the straight tube portion 12 and the spigot portion 13 are integrally formed as a pipe body, and the pipe body and the socket portion 11 are manufactured separately and then welded together. The straight tube portion 12 and the spigot portion 13 are both cylindrical, and the spigot portion 13 is chamfered along the circumferential direction. The inner diameter, outer diameter, and thickness of the straight tube portion 12 are equal to the inner diameter, outer diameter, and thickness of the spigot portion 13, respectively.

The inner surface of the socket portion 11 is provided with steps or grooves. When two pipes are connected, the socket portion 13 of one pipe is inserted into the socket portion 11 of the adjacent pipe and sealed by a sealing ring. In this embodiment, the socket portion 11 is provided with a first step 111 and a second step 112 in sequence from the end far away from the straight tube portion 12 to the end close to the straight tube portion 12 . The inner wall of the first step 111 is a cylindrical wall. The inner wall of the second step 112 is the outer surface of the truncated cone, that is, the inner diameter of the second step 112 gradually increases from the first step 111 toward the straight tube portion 12 , which is equivalent to a bell mouth. Preferably, the maximum inner diameter of the second step 112 is smaller than the inner diameter of the first step 111 . The minimum inner diameter of the second step 112 is larger than the inner diameter of the straight tube portion 12 . In this way, one end of the straight tube portion 12 close to the second step 112 forms a third step. The inner wall bell mouth of the second step 112 is provided to provide a deflection angle for the adjacent pipes connected to it, that is, to allow the center line of one pipe to intersect with the center line of the adjacent pipes connected to it, instead of Coincidence state, this is to allow a certain installation error and facilitate actual operation.

The inner tube 2 is made of metal materials with corrosion resistance, including but not limited to stainless steel, titanium, preferably stainless steel, and is cylindrical.

The material of the middle layer 3 is non-metal, preferably hot melt adhesive, plastic or rubber. When the material of the middle layer 3 is hot melt adhesive, the hot melt adhesive has bonding properties, and the inner tube 2 and the outer tube 1 are bonded together through the middle layer 3; when the material of the middle layer 3 is plastic or rubber, the plastic or Rubber does not have adhesive properties, and the inner tube 2 presses the middle layer 3 against the inner wall of the outer tube 1.

The length of the inner tube 2, the length of the middle layer 3 and the length of the tube body (straight tube part 12 and socket part 13) are equal to each other. At one end of the socket portion 11, the end of the inner tube 2, the end of the middle layer 3 and the end of the straight tube portion 12 are flush; at one end of the socket portion 13, the end of the inner tube 2, the end of the middle layer 3 The end portion and the end portion of the socket portion 13 are flush with each other.

The thickness of the middle layer 3 is not less than 0.2mm, and the thickness of the inner tube 2 is not less than 0.1mm.

The main function of the inner tube 2 is anti-corrosion, and the thickness should not be large. A large number of welding tests have shown that under the conditions of fiber laser welding process, stainless steel plates can obtain welds with high welding strength and small deformation at a minimum wall thickness of 0.1mm. . Considering the complexity of the welding process equipment, investment cost, and the fact that the middle layer 3 shrinks at low temperatures due to its large thermal expansion coefficient, causing internal stress that is separated from the outer tube 1, it is necessary to exert the supporting role of the inner tube 2 on the middle layer 3. To offset the internal stress between the outer tube 1 and the middle layer 3, the preferred thickness of the inner tube 2 is 0.1mm-2mm.

When the material of the middle layer 3 is hot melt adhesive, it serves as an adhesive layer. When the inner wall of the outer tube 1 is relatively rough during compounding, the middle layer will be heated and melted to fill the pits on the inner wall of the outer tube 1. If the thickness of the middle layer 3 is too small, Poor adhesion is likely to occur in areas with large local roughness. At the same time, the middle layer 3 also serves as an insulating layer, which requires a certain thickness to produce an insulation effect between the outer tube 1 and the inner tube 2. The electric spark test and the peel strength test show that when the thickness of the middle layer 3 reaches more than 0.2mm, it can be stably obtained. Excellent peel strength and insulation properties. The preferred one is 0.2mm-2mm.

Compared with the stainless steel lining thickness required by the standard "Stainless Steel Lined Composite Steel Pipe (CJ/T 192-2017)", when the middle layer 3 uses hot melt adhesive, the stainless steel lining thickness is thinner and the cost is lower. When the inner diameter of the outer pipe 1 is the same, the inner diameter of the pipe is larger and the transportation efficiency is higher.

When the inner diameter of the outer pipe 1 is 100-300mm, the lining is stainless steel, and the thickness of the stainless steel is 0.5-0.9mm, the bonding strength of the stainless steel lining and the outer pipe 1 does not meet the standard "Stainless Steel Lined Composite Steel Pipe (CJ/T 192) -2017)》Requirements, when used, the composite area is prone to peeling, and the lining is easily washed away by liquid.

Lining peel strength test (this test uses an outer tube inner diameter of 100-300mm and a stainless steel lining thickness of 0.1mm-0.3mm) and the conclusions are as follows:

When the rust removal level of the inner wall surface of the metal outer pipe 1 reaches Sa2.5 level, the surface roughness is Ra12.5~Ra25, and the thickness of the middle layer 3 is not less than 0.2mm, the peeling strength of the hot melt adhesive and the outer pipe can be The peel strength of hot melt adhesive and lining can stably reach above 70N/cm; the peel strength of hot melt adhesive and lining can stably reach above 50N/cm;

When the rust removal level of the inner wall surface of the metal outer pipe 1 reaches Sa2.5 level, the surface roughness is Ra25~Ra50, and the thickness of the middle layer 3 is more than 0.2mm, the peeling strength of the hot melt adhesive and the outer pipe can stably reach Above 120N/cm; the peel strength of hot melt adhesive and lining can stably reach above 50N/cm;

When the rust removal level of the inner wall surface of the metal outer pipe 1 reaches Sa2.5 level, the surface roughness is greater than Ra50, and the thickness of the middle layer 3 is more than 0.2mm, the peeling strength of the hot melt adhesive and the outer pipe can stably reach 150N/cm. Above; the peel strength of hot melt adhesive and lining can stably reach above 50N/cm.

According to hydraulic calculations, in existing liquid transportation pipelines, the maximum lateral flushing force of liquid is 1.15MPa. The peeling strength of the hot melt adhesive and lining of this solution can reach 50N/cm, and the corresponding bonding strength is 5MPa, which is the The horizontal scouring force of liquid that the pipe can withstand is 5MPa.

When the middle layer 3 is made of hot melt adhesive, the thickness of the middle layer 3 is preferably 0.2 mm to 0.5 mm. When the thickness of the middle layer 3 is greater than 0.5 mm, the peel strength is basically unchanged.

The socket portion 13 of the pipe is provided with a lining ring 5 and a sealing gasket 4 at one end, and the socket portion 11 is also provided with a lining ring 5 and a sealing gasket 4 at one end. The backing ring 5 is made of corrosion-resistant metal, preferably stainless steel, and the sealing gasket 4 is made of rubber. The sealing gasket 4 at one end of the socket portion 13 is used to cover and compress the end surface and inner wall of the socket portion 13 of the pipe, and the lining ring 5 is pressed against the sealing gasket 4 . The sealing gasket 4 at one end of the socket 11 is used to cover and compress the end surface and inner wall of the straight pipe portion 12 close to one end of the socket 11 of the pipe, and the lining ring 5 is pressed against the sealing gasket 4 .

As shown in Figures 3 and 4, the gasket 4 includes a gasket flange 41 and a gasket flange 42. The gasket flange 41 and the gasket flange 42 are integrally connected. The gasket flange 41 can be regarded as thinner. It is cylindrical, and the sealing gasket flange 42 is annular. The inner diameter of the gasket flange 42 is equal to the inner diameter of the sealing flange 41 , and the outer diameter of the gasket flange 42 is larger than the outer diameter of the sealing flange 41 . The gasket pressing edge 41 and the gasket flange 42 share a center line.

The structure of the lining ring 5 is similar to that of the sealing gasket 4. The lining ring 5 includes an integrally connected lining ring flange 51 and a lining ring flange 52. The lining ring flange 51 can be regarded as a thin cylinder, and the lining ring flange 52 is circular. The inner diameter of the lining ring flange 52 is equal to the inner diameter of the lining ring flange 51 , and the outer diameter of the lining ring flange 52 is larger than the outer diameter of the lining ring flange 51 . The backing ring flange 51 and the backing ring flange 52 share a center line.

In this embodiment, the length H of the backing ring retaining edge 51 is not less than 20 mm.

In the view shown in FIG. 4 , the upper end surface of the gasket flange 42 does not exceed the upper end surface of the backing ring flange 52 .

At one end of the socket portion 11 , the outer surface of the sealing edge 41 of the gasket 4 is in contact with the inner surface of the inner tube 2 , and the inner surface of the sealing edge 41 is in contact with the outer surface of the lining ring 5 . One side of the gasket flange 42 fits the end surface of the inner tube 2 , the middle layer 3 , and the straight tube portion 12 , and the other side of the gasket flange 42 fits the bushing ring 5 . The lining ring flange 51 of the lining ring 5 fits and compresses the sealing gasket flange 41 , and the lining ring flange 52 fits and compresses the sealing gasket flange 42 .

At one end of the socket portion 13 , the outer surface of the sealing edge 41 of the sealing gasket 4 is in contact with the inner surface of the inner tube 2 , and the inner surface of the sealing edge 41 is in contact with the outer surface of the bushing ring 5 . One side of the gasket flange 42 fits the end surface of the inner tube 2 , the middle layer 3 and the socket portion 13 , and the other side of the gasket flange 42 fits the bushing ring 5 . The lining ring flange 51 of the lining ring 5 fits and compresses the sealing gasket flange 41 , and the lining ring flange 52 fits and compresses the sealing gasket flange 42 .

A method for manufacturing corrosion-resistant metal-lined socket-type multi-layer pipes, which is used to manufacture the pipes, including the following steps:

Step S1: Process the inner and outer walls of the outer tube 1, make the inner tube 2, and make the lining ring 5.

In this step, the method for processing the inner and outer walls of the outer pipe 1 is to first polish the inner wall of the outer pipe 1 and then sandblast or shot blast the inner and outer walls. Use an internal grinder to grind the inner wall of the metal outer pipe 1 to smooth the inner wall of the pipe and remove surface oxide scale, scum, rust, etc. Alternatively, after polishing the inner wall of the outer pipe 1 smooth, use a laser cleaning machine to clean the inner wall of the pipe to deeply remove the oxide scale and rust on the inner wall of the pipe. During sandblasting or shot blasting, dust, oxide scale, and rust on the inner and outer walls are removed, and the inner and outer walls of the pipe are sandblasted to form a frosted surface.

Making inner tube 2 includes the following steps:

Step S11: Process the stainless steel sheet into a ring shape or a thin cylindrical shape, and complete the rolling. In this step, the rounding is performed by a rounding machine.

Step S12: Cut the rolled stainless steel sheet and weld it into a cylindrical shape to obtain the tube blank of the inner tube 2. In this step, if what is obtained in step S11 is a single rolled circle, use an argon arc welding machine or a laser welding machine to perform straight seam welding, and the welding seam extends from one end of the inner tube 2 to the other end. If what is obtained in step S11 is a plurality of spirally connected rolled circles, a spiral seam welding machine is used to weld the plurality of spirally connected rolled circles in sequence to form a thin cylindrical shape.

Preferably, the length of the stainless steel round pipe obtained in step S12 is greater than the length of the inner pipe 2 of the finally processed pipe. Specifically, the length of the stainless steel round tube obtained in step S12 is greater than the sum of the length of the straight tube portion 12 and the length of the socket portion 13 .

When making the backing ring 5, two sections can be cut from the stainless steel round tube obtained in step S12 as the backing ring 5 tube blanks. Or make the backing ring 5 separately. The making method of the backing ring 5 is as follows:

Step S11’: Use a flanging and rolling machine to process the stainless steel sheet into a rolled circle with flanges, that is, process it into a structure with a lining ring flange 51 and a lining ring flanging 52. In this step, the rounding is performed by a rounding machine.

Step S12': Use an argon arc welding machine or a laser welding machine to weld the rounded notch obtained in step S11' to form the shape of the backing ring 5.

Step S13': Put the sealing gasket 4 on the outer wall of the lining ring 5 obtained in step S12'.

Step S2: Arrange the inner tube 2, the middle layer 3 and the outer tube 1 in sequence from the inside to the outside.

In this step, when the material of the middle layer 3 is hot melt glue or plastic, step S2 can be completed in the following three ways:

The first way is as follows:

First, the hot melt glue or plastic is formed into a round tube through extrusion molding, vacuum sizing, traction, and cutting. Extruders, vacuum boxes, traction machines, and cutting machines in the existing technology can be used to perform extrusion molding, vacuum sizing, traction, and cutting respectively. The extrusion molding is an existing technology and will not be described in detail here.

Then, the obtained formed intermediate layer 3 is sleeved on the outer wall of the inner tube 2 . In this step, casing can be performed manually or with a casing machine.

Finally, the intermediate layer 3 and the inner tube 2 that are sheathed together are inserted into the outer tube 1 as a whole. Similarly, in this step, the tube threading can be completed manually or with a tube threading machine.

The second way is as follows:

First, after the inner wall of the outer tube 1 is heated, the powdered hot melt adhesive or plastic is rotomolded or spray-molded on the inner wall of the straight tube portion 12 and the inner wall of the socket portion 13 of the outer tube 1 using a roller coating machine or a plastic coating machine. The thickness of rotational molding or spray molding is greater than 0.2mm.

Then, the inner tube 2 is inserted into the outer tube 1 with the intermediate layer 3 on the inner wall.

The third way is as follows:

First, after heating the outer wall of the inner tube 2, use a roller coating machine or a plastic coating machine to roll or spray powder hot melt adhesive or plastic on the outer wall of the stainless steel inner tube 2. The thickness of rotational molding or spray molding is greater than 0.2mm. Then, the inner tube 2 with the intermediate layer 3 on the outer wall is inserted into the outer tube 1 .

When the material of the middle layer 3 is rubber, first roll the rubber plate on the outer wall of the inner tube 2, then use adhesive to bond the rubber joints, and then insert the rubber-covered inner tube 2 into the outer tube 1 . Or put the rubber tube on the outer wall of the inner tube 2 and then insert it into the outer tube 1 as a whole. The length of the rubber should be enough to cover the inner wall of the straight tube part 12 and the inner wall of the socket part 13.

Step S3: Press the inner tube 2 and the middle layer 3 onto the outer tube 1.

This step can be accomplished by spin forming or hydroforming. During spin forming, a pipe spinning machine is used to spin the inner tube 2 so that the inner tube 2, the middle layer 3, and the outer tube 1 are in close contact with each other in sequence. During hydroforming, both ends of the stainless steel inner tube 2 that penetrates the outer tube 1 are sealed, and water is injected into the tube to pressurize the inner tube 2, the middle layer 3, and the outer tube 1 in order.

Step S4: Compound.

In this step, the pipe is heated by an intermediate frequency inductor or a heating furnace, the hot melt glue melts, and after cooling, the outer pipe 1 and the inner pipe 2 are bonded together.

When the material of the middle layer 3 is plastic or rubber, there is no step S4.

Step S5: Lining ring.

In this step, first, manually place two lining rings 5 covered with sealing gaskets 4 into both ends of the pipe. Then, use an expanding machine to expand the diameter of the lining ring 5 so that the lining ring 5 presses the sealing gasket 4 against the inner wall and end face of the pipe.

If the lining ring 5 embryo is two sections cut from the stainless steel round pipe obtained in step S12, then in this step, after the lining ring 5 with the sealing gasket 4 is inserted into the pipe end, flanging is required to form the lining ring. Flange 52.

After completing the above steps, remove excess burrs, and spray paint or plastic coat the outer wall of the pipe or perform external anti-corrosion treatment in other ways.

Finally, it is necessary to explain here that the above examples are only used to further explain the technical solution of the present invention in detail and cannot be understood as limiting the protection scope of the present invention. Those skilled in the art will make some decisions based on the above content of the present invention. Non-essential improvements and adjustments belong to the protection scope of the present invention.

Claims (15)

1. The utility model provides a socket joint formula multilayer tubular product of corrosion-resistant metal lining, its characterized in that, including inner tube (2), intermediate level (3) and outer tube (1) that cup joint in proper order from inside to outside, bellmouth portion (11) inner wall is equipped with ladder and/or recess, and inner tube (2), intermediate level (3) and outer tube (1) bond into tubular product or compress tightly and constitute tubular product, outer tube (1) are including bellmouth portion (11), straight tube portion (12) and socket portion (13) that connect gradually, and at least one deck of inner tube (2) and outer tube (1) is metal material.

2. The multilayer tubing of claim 1, wherein: the outer tube (1) is made of metal material.

3. The multilayer tubing of claim 2, wherein: the material of the middle layer (3) is a nonmetallic material.

4. A multilayer pipe according to claim 3, characterized in that: the material of the middle layer (3) is hot melt adhesive.

5. A multilayer pipe according to claim 3, characterized in that: the middle layer (3) is made of plastic.

6. A multilayer pipe according to claim 3, characterized in that: the material of the middle layer (3) is rubber.

7. The multilayer pipe according to any one of claims 4 to 6, characterized in that: the inner tube (2) is made of a material with a corrosion resistance function.

8. The multilayer pipe according to any one of claims 4 to 6, characterized in that: the thickness of the middle layer (3) is not less than 0.2mm, and the thickness of the inner tube (2) is not less than 0.1mm.

9. The multilayer tubing of claim 1, wherein: at one end of the bell mouth part (11), the end face of the inner tube (2), the end face of the middle layer (3) and the end face of the straight tube part (12) are flush, and at one end of the socket part (13), the end face of the inner tube (2), the end face of the middle layer (3) and the end face of the socket part (13) are flush.

10. The multilayer pipe according to any one of claims 4 to 6, characterized in that: each end of the pipe is provided with a sealing gasket (4) and a lining ring (5), one end of the socket part (11), the sealing gasket (4) is used for wrapping the end face of the straight pipe part (12), the end face of the middle layer (3), the end face of the inner pipe (2) and the inner wall of one end of the inner pipe (2), the sealing gasket (4) is used for wrapping the end face of the socket part (13), the end face of the middle layer (3), the end face of the inner pipe (2) and the inner wall of the other end of the inner pipe (2), the lining ring (5) is used for tightly pressing the sealing gasket (4), when the pipe is used, the lining ring (5) and the sealing gasket (4) at one end of the socket part (13) form full sealing to the end face of the socket part (13), and the lining ring (5) and the sealing gasket (4) at one end of the socket part (11) form full sealing to the end face of the straight pipe part (12).

11. The multilayer tubing of claim 10, wherein: the sealing gasket (4) comprises a sealing gasket pressing edge (41) and a sealing gasket flanging (42), the sealing gasket pressing edge (41) is cylindrical, the sealing gasket flanging (42) is annular, the lining ring (5) comprises a lining ring pressing edge (51) and a lining ring flanging (52), the lining ring pressing edge (51) and the lining ring flanging (52) are integral, the lining ring pressing edge (51) is cylindrical, the lining ring flanging (52) is annular, the lining ring pressing edge (51) presses the sealing gasket pressing edge (41), and the lining ring flanging (52) presses the sealing gasket flanging (42).

12. The multilayer tubing of claim 11, wherein: the length of the lining ring blank (51) is not less than 20mm.

13. A method for manufacturing a corrosion-resistant metal lined socket multi-layer pipe, for manufacturing a pipe according to any one of claims 4 to 6, characterized in that: the method comprises the following steps:

step S1: treating the outer tube (1), manufacturing the inner tube (2) and the middle layer (3);

step S2: the inner tube (2), the middle layer (3) and the outer tube (1) are sequentially arranged from inside to outside;

step S3: pressing the inner tube (2) and the middle layer (3) on the outer tube (1);

step S4: compounding;

when the material of the intermediate layer (3) is plastic or rubber, the step S4 is not provided.

14. The manufacturing method according to claim 13, characterized in that: the manufacturing method further includes step S5: the lining ring is sleeved with a sealing gasket (4) and a lining ring (5) at each end of the pipe.

15. The manufacturing method according to claim 13, characterized in that: when the intermediate layer (3) is hot melt adhesive or plastic, in the step S1, the tubular intermediate layer (3) can be independently manufactured, and in the step S2, the intermediate layer (3) is sleeved outside the inner pipe (2) and then integrally sleeved into the outer pipe (1); or firstly, powdered hot melt adhesive or plastic is rotationally molded or sprayed on the inner wall of the outer tube (1), and then the inner tube (2) is sleeved into the outer tube (1) in the step S2; or firstly, powdered hot melt adhesive or plastic is rotationally molded or sprayed on the outer wall of the inner tube (2), and then the inner tube (2) is sleeved into the outer tube (1) in the step S2.