CN117927743A - Plastic steel composite pipe and preparation method thereof - Google Patents

Abstract

The invention discloses a plastic-steel composite pipe, which comprises a steel pipe matrix, wherein the outer surface of the steel pipe matrix is wrapped with vacuum glue-dipped fiber cloth, and a composite plastic outer layer is formed on the outer pipe surface of the steel pipe matrix wrapped with the vacuum glue-dipped fiber cloth; the composite plastic outer layer comprises a first plastic body, the first plastic body is of a prefabricated sleeve structure, and a plurality of annular blind grooves are formed in the inner side of the first plastic body; the vulcanized silicone rubber is used as a filling structure layer between the first plastic body and the steel pipe matrix; the plastic-steel composite pipe is characterized in that a second plastic body is further formed on the inner pipe surface of the steel pipe matrix and the outer pipe surface of the first plastic body. The invention also discloses a preparation method of the plastic steel composite pipe. The plastic steel composite pipe prepared by the invention integrates the characteristics of various pipelines, has the characteristics of steel pipe strength, corrosion resistance, abrasion resistance, small fluid resistance and the like, and is a green pipeline with high safety and sanitation strength and good bonding strength.

Description

Plastic steel composite pipe and preparation method thereof

Technical Field

The invention relates to a composite pipe technology in the field of pipe fitting preparation, in particular to a plastic steel composite pipe and a preparation method thereof.

Background

The plastic steel composite pipe is used as a novel pipe, is one of the pipes with the best comprehensive performance at present, takes a steel pipe as a matrix, is obtained by welding plastic material outer layers on the inner surface or the inner surface and the outer surface of the steel pipe through forming processes such as spraying, rolling, soaking, sucking and the like, has the advantages of both plastic pipes and metal pipes, has very high strength and rigidity, and has the plastic material outer layer formed on the surface, so that the mechanical performance of the steel pipe can be further enhanced, the steel pipe of the inner layer is protected from external corrosion by the plastic material outer layer energy efficiency, and the defects that the galvanized pipe is easy to rust, yellow water is generated, the pipe caliber is small, the blockage is caused due to the accumulation of the yellow water, the strength of the plastic pipe is weak and the like are overcome, and the plastic pipe has small medium flow resistance. The plastic steel composite pipe has the technical advantages of long overall service life and wide application range, is suitable for conveying mediums such as seawater, warm water, oil, gas and the like, has obvious effects of preventing secondary pollution and improving water quality, and has unique advantages on urban drinking water and industrial water supply pipelines.

The plastic steel composite pipe is various in types and models, and the thickness of the plastic anti-corrosion layer and the molding mode of the plastic composite pipe are different according to different purposes, but under the condition of the traditional molding mode in the prior art, the following problems exist in the practical application process of the molded plastic steel composite pipe structure:

1. The traditional spin-coating forming mode is mainly to directly adopt plastic powder to directly carry out spin-coating forming on the surface of a steel pipe, but the spin-coating forming mode can cause the problems of uneven distribution of the plastic powder and uneven coating thickness, the plastic powder needs a certain time to enable the plastic material to be solidified on the surface of a steel pipe matrix, the plastic coating material easily flows in the solidification process to cause uniformity defects on the surface of the steel pipe, the plastic coating layer of the plastic-coated steel pipe is usually thinner in the use process, and the plastic layer of the plastic-coated steel pipe is easily damaged locally to lose efficacy when a medium-and-large-size plastic-steel composite pipe with a large-size and thicker plastic outer layer is formed, so that the application range of the plastic-coated steel pipe is influenced;

2. In the use process, the plastic steel composite pipe molded under the condition of a fixedly connected molding mode similar to the lining plastic of a non-spraying process has defects in bonding strength due to the material difference between the outer layer of the plastic material and the steel pipe matrix, and in the use process, interlayer structure stripping easily occurs at the bonding interface position of the outer layer of the plastic material and the steel pipe matrix due to external stress impact, temperature change and other reasons, so that the integral consistency of the composite pipe is damaged, the strength and structural defects of the composite steel pipe are caused, and the service performance and service life of the pipe are directly influenced; such defects become more pronounced during outdoor or pre-buried paving due to the effects of climate change, animal and plant activity and soil environmental stresses.

For the above reasons, there is a need for improvements in the structure and forming process of plastic steel composite pipes in the prior art.

Disclosure of Invention

The technical problem solved by the invention is to provide a plastic steel composite pipe and a preparation method thereof, so as to solve the defects in the technical background.

The technical problems solved by the invention are realized by adopting the following technical scheme:

the plastic steel composite pipe comprises a steel pipe substrate, wherein the outer surface of the steel pipe substrate is wrapped with vacuum glue-dipped fiber cloth, and a composite plastic material outer layer is formed on the outer pipe surface of the steel pipe substrate wrapped with the vacuum glue-dipped fiber cloth;

The composite plastic outer layer comprises a first plastic body, the first plastic body is of a prefabricated sleeve structure, the sleeve thickness of the first plastic body is 1/3-1/2 of the sleeve thickness of the steel pipe matrix, and the first plastic body is concentrically sleeved on the outer pipe surface of the steel pipe matrix; the inner side of the first plastic body is provided with a plurality of annular blind grooves at intervals along the length direction of the pipe body, the annular blind grooves adjacent to each other in position are reserved with communication parts at the joint sides corresponding to the steel pipe base body, and anchor columns arranged in an array are formed in the annular blind grooves;

A glue injection gap is reserved between the sleeve pipe body of the first plastic body and the steel pipe matrix wrapped with the vacuum glue-dipped fiber cloth, and the top surface of the anchor post is tightly pressed on the surface of the vacuum glue-dipped fiber cloth of the steel pipe matrix;

The gap space between the first plastic body and the steel pipe matrix takes vulcanized silicone rubber as a filling structure layer, and modified reinforcing fibers with the mass ratio of 7-12% are further doped in the filling structure layer;

the plastic steel composite pipe is characterized in that a second plastic body is further formed on the inner pipe surface of the steel pipe substrate and the outer pipe surface of the first plastic body, the second plastic body is a film material with the thickness of 0.2-0.3 mm, and the second plastic body is formed on the surface structure through a spin coating process or a hot dip molding process.

As a further limitation, the steel pipe substrate is a galvanized welded steel pipe or a galvanized seamless steel pipe or a spiral steel pipe subjected to surface polishing treatment.

As a further limitation, the first plastic body is formed with a horn-shaped guide structure on the end surface for facilitating the loading of the steel pipe matrix, the horn-shaped guide structure is a residual structure, and the first plastic body is sawed out after being assembled in place on the steel pipe matrix.

As further limitation, the sum of the lengths of the annular blind grooves formed on the first plastic body is 75% -85% of the whole length of the pipe, and the length-diameter ratio of each annular blind groove is 3:1-5:1; and the gap between the corresponding ring surface of the bottom of the annular blind groove and the surface of the steel pipe matrix wrapped with the vacuum glue-dipped fiber cloth is 1/5-1/3 of the pipe thickness of the first plastic sleeve.

As a further limitation, the communicating part is an annular inward neck structure formed between annular blind grooves adjacent to each other at the position and attached to the side of the steel pipe substrate or a plurality of connecting channels formed on the side wall between the annular blind grooves adjacent to each other at the position, and the connecting channels are uniformly arranged on the corresponding annular surfaces; the projection size of the communication part on the radial section of the plastic steel composite pipe is 20-30% of the projection size of the annular blind groove on the radial section of the plastic steel composite pipe.

As a further definition, the cross section of the anchor post is cross-shaped or circular; the area of the anchor post in the setting plane of the annular blind groove is 7-15%.

As a further limitation, the substrate of the vacuum glue-dipped fiber cloth is glass fiber cloth or aramid fiber cloth or carbon fiber cloth modified by using a silane coupling agent; the modified reinforcing fiber is a monofilament fiber modified by a silane coupling agent, the monofilament length of the monofilament fiber is 4-7 mm, the fineness is 1-1.5D, and the fiber type is the same as the base material of the vacuum glue-dipped fiber cloth.

By way of further limitation, the filler structural layer is a unitary injection molded structure.

The preparation method of the plastic steel composite pipe is used for preparing the plastic steel composite pipe, and specifically comprises the following operation steps:

S1, cleaning the surface of a steel pipe matrix, and respectively carrying out rust removal and dust removal on the inner surface and the outer surface of the steel pipe matrix; spraying a silane coupling agent on the surface of the steel pipe matrix after the rust removal and dust removal treatment is finished, standing at room temperature, placing the steel pipe matrix in a baking oven after the surface is dried, baking the steel pipe matrix for 30 to 50 minutes at the temperature of 40 to 60 ℃, and naturally cooling the steel pipe matrix;

s2, carrying out pipe end wrapping on the cooled steel pipe matrix; then wrapping vacuum glue-dipped fiber cloth on the surface of the steel pipe matrix after the pipe end is wrapped, taking the pipe end wrapping paper at two ends of the steel pipe matrix as a boundary when wrapping the vacuum glue-dipped fiber cloth, and removing the pipe end wrapping paper after the wrapping of the vacuum glue-dipped fiber cloth is completed;

s3, selecting a first plastic body matched with the size of the steel pipe matrix, and sleeving one end of the steel pipe matrix, wherein the outer side of the first plastic body is pressed on the paper winding position of the original pipe end in a pressing mode, so that the vacuum glue-dipped fiber cloth area is buried in the first plastic body;

S4, taking vulcanized silicone rubber as a raw material, performing pressure injection from a reserved injection hole position on the first plastic body to enable the vulcanized silicone rubber to fill a gap space between the first plastic body and the steel pipe matrix, then scraping off excessive sizing material, and performing heat vulcanization treatment;

And S5, treating the pipe treated in the step S4 by using a spin coating process or a hot dip molding process to obtain a second plastic body, polishing the end after the treatment is finished, and obtaining the finished plastic steel composite pipe after the detection is qualified.

The plastic steel composite pipe has the following advantages and beneficial effects:

Compared with other metal pipes, plastic pipes and composite pipes, the plastic steel composite pipe has the advantages of low water absorption, high mechanical strength and excellent structural stability, the pipe takes the steel pipe as a matrix and has better physical strength, the first plastic body and the second plastic body of the outer layer can effectively protect the steel pipe of the inner layer from external corrosion, and the plastic material can also ensure that the pipe body is not influenced by other corrosive liquids or environmental corrosion conditions. The corrosion resistance can greatly prolong the service life of the composite pipe, reduce the frequency of maintenance and replacement of the steel pipe and reduce the use cost; meanwhile, the inner side surface of the pipe is smooth, so that the conveying efficiency and the conveying performance of the pipeline can be improved, the conveying resistance is reduced, and the energy consumption is reduced;

Compared with the traditional plastic steel composite pipe, the combined molding mode of the first plastic body and the second plastic body has the technical advantages of both plastic coated steel pipes and plastic lined steel pipes, can ensure the combination property of plastic materials and steel pipes and the stability of pipe structures, can effectively avoid the reduction of external force impact resistance and the peeling of interfaces between plastic materials and steel pipes caused by material differences through gap filling of vulcanized silicone rubber, and can further improve the service performance and the service life of the plastic steel composite pipe; the method is particularly suitable for preparing medium-large-size pipes and improves the service life of the pipes;

The plastic steel composite pipe has stronger adaptation to external environment change and stress impact, can be suitable for working environments of-30 ℃ to 120 ℃ and use environments such as buried, acid-base corrosion environments, flying sand dust and the like, can effectively widen the application scene of the plastic steel composite pipe, and can effectively prevent plant root systems and soil environment stress from being damaged.

Compared with the traditional plastic steel composite pipe with the same size, the plastic steel composite pipe has the advantages of light weight and easiness in carrying, installing and maintaining. In the construction process, the time can be greatly shortened, the efficiency is improved, and the labor cost is reduced.

Drawings

Fig. 1 is a schematic axial cross-section of the present invention.

Fig. 2 is an enlarged schematic view of a detail of the portion a in fig. 1.

Fig. 3 is an enlarged schematic view of a detail of the portion B in fig. 1.

Wherein: 1. a steel pipe substrate; 2. an outer layer of composite plastic material; 3. a second plastic body; 20. a first plastic body; 21. filling a structural layer; 22. an annular blind groove; 23. an anchor post; 24. vacuum gum dipping fiber cloth; 25. and a communication part.

Detailed Description

The invention is further described with reference to the following detailed drawings in order to make the technical means, the creation characteristics, the achievement of the purpose and the effect of the implementation of the invention easy to understand.

In the following examples, it will be understood by those skilled in the art that all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs unless defined otherwise. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Referring to the preferred embodiment of a plastic steel composite pipe in fig. 1 to 3, in this embodiment, the main body of the plastic steel composite pipe is a steel pipe substrate 1, the steel pipe substrate 1 may be a galvanized welded steel pipe or a galvanized seamless steel pipe or a spiral steel pipe after surface polishing treatment in different embodiments, and the steel pipe substrate 1 may have different pipe thicknesses under different requirements, and generally includes various choices of 0.5mm, 1.0mm, 1.2mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 4.0mm, 5.0mm, 6.0mm, etc., and considering the molding difficulty, the structural stability after molding and the use condition, the steel pipe substrate 1 should preferably adopt a medium and large-size steel pipe with the pipe thickness of 3mm or more as a raw material pipe. Meanwhile, the surface of the steel pipe matrix 1 is also wrapped with vacuum glue-dipped fiber cloth 24 as an interface stable structure during molding; the vacuum glue-dipped fiber cloth 24 also reserves a section of unwrapped parts at two ends of the steel tube substrate 1 to serve as a buffer area.

The outer tube surface of the steel tube matrix 1 is molded with a composite plastic outer layer 2, and the outer surface of the whole composite plastic outer layer 2 and the inner tube surface of the steel tube matrix 1 are molded with a second plastic body 3. The second plastic body 3 is a plastic film with a thickness of 0.2-0.3 mm, and in different embodiments, there are two molding modes:

firstly, forming the surface structure by matching a spin coating process with a pipe fitting spin coating device;

and secondly, the surface structure is formed by a hot dip molding process and hot dip molding equipment.

In this embodiment, the main body of the composite plastic outer layer 2 includes a first plastic body 20, the first plastic body 20 is a prefabricated and formed sleeve structure, and is fixed on the outer tube surface of the steel tube base 1 in a sleeved mode by a jig during forming, and the sleeve thickness of the first plastic body 20 is 1/3-1/2 of the sleeve thickness of the steel tube base 1.

The inner side of the first plastic body 20 is provided with a plurality of annular blind grooves 22 at intervals along the length direction of the pipe body, and the annular blind grooves 22 have consistent size, shape and structure and are arranged at equal intervals along the length direction of the inner side of the first plastic body 20. In different embodiments, the length-diameter ratio of the single annular blind groove 22 is 3:1-5:1, and 1/5-1/3 of the sleeve thickness corresponding to the first plastic body 20 is reserved between the corresponding annular surface of the groove bottom of the single annular blind groove and the surface of the vacuum glue-dipped fiber cloth 24 wrapped on the steel pipe substrate 1. The sum of the lengths of the annular blind grooves 22 of the first plastic body 20 in unit length is 75% -85% of the whole length of the pipe.

The first plastic body 20 is formed with a communication portion 25 at a position region between the annular blind grooves 22 corresponding to the inside of the sleeve body, and the communication portion 25 is used for forming a communication space between the annular blind grooves 22. The communication portion 25 has two structural forms in different embodiments:

A toroidal structure of variable diameter structure as shown in figure 1, namely an annular inner neck structure formed between adjacent annular blind grooves 22 and corresponding to the leaning side of the steel tube matrix 1;

And the other is to form a plurality of channel connection structures on the side wall of the connection side of the adjacent annular blind groove 22, and the plurality of channels are uniformly arranged on the corresponding annular surface of the annular blind groove 22, namely are radially arranged in an annular shape.

Common to the two different configurations of the communication portion 25 is: the projection size of the corresponding communication part 25 on the radial section of the plastic steel composite pipe is 20-30% of the projection size of the annular blind groove 22 on the radial section of the plastic steel composite pipe, so that the structural stability, strength and shock resistance of the side wall serving as a partition and supporting function between the annular blind grooves 22 are ensured.

In addition, in the embodiment of the invention, anchor posts 23 arranged in an array are also formed in the bottoms of the corresponding annular blind grooves 22, and the cross sections of the anchor posts 23 are cross-shaped or circular; the area occupation ratio of the anchor post 23 in the annular blind groove setting plane is 7-15%; and the top surface of the anchor post 23 is tightly pressed on the surface of the vacuum glue-dipped fiber cloth 24 of the steel pipe matrix 1.

The gap between the steel pipe base body 1 and the first plastic body 20 and the gap between the corresponding anchor posts 23 in the annular blind groove 22 are glue injection gaps, and the glue injection gaps are filled with vulcanized silicone rubber as a filling structure layer 25. As a preferred molding method, the vulcanized silicone rubber in the filling structure layer 25 is an integrally molded structure of a single injection.

The plastic steel composite pipe of the embodiment is prepared by the following steps:

In order to enable the plastic material to be better molded on the pipe wall of the steel pipe matrix 1, the steel pipe matrix 1 needs to be cleaned firstly, namely, the steel pipe of the steel pipe matrix 1 serving as a raw material needs to be cleaned on the surface, after the cleaning is finished, the steel pipe is preheated on the surface by using heat treatment equipment to remove moisture, then surface dust is blown away by a dust remover, then the outer surface and the inner surface of the steel pipe are derusted by using a shot blasting machine and an inner derusting head respectively, after the derusting is finished, the steel pipe matrix 1 after the derusting is finished is dedusted by using a roller brush dust remover, and the steel pipe matrix 1 which can be used for processing is obtained after the dedusting is finished.

And (3) carrying out surface silane coupling agent spraying treatment on the obtained steel pipe substrate 1, standing at room temperature after spraying, placing the steel pipe substrate in an oven after the surface is dried, baking the steel pipe substrate in the oven at 50 ℃ for 40min, and naturally cooling the steel pipe substrate. Winding paper at the pipe ends of the two ends of the cooled steel pipe matrix 1; and then wrapping the vacuum glue-dipped fiber cloth 24 on the surface of the steel pipe substrate 1 after the pipe end is wrapped, taking the pipe end wrapping paper at the two ends of the steel pipe substrate 1 as a boundary when wrapping the vacuum glue-dipped fiber cloth 24, removing the pipe end wrapping paper after the wrapping of the vacuum glue-dipped fiber cloth is completed, and carrying out surface rolling on the steel pipe substrate 1 so as to ensure the fitting degree of the vacuum glue-dipped fiber cloth 24 and the steel pipe substrate 1. The vacuum gum dipping fiber cloth 24 should adopt fiber cloth with better physical and chemical properties as a base material (such as glass fiber cloth or aramid fiber cloth or carbon fiber cloth), and the corresponding base material needs to be pretreated by a silane coupling agent before gum dipping; and the corresponding prepreg glue is epoxy resin glue.

Then the composite plastic outer layer 2 is formed, a first plastic body 20 matched with the steel pipe matrix 1 in size is selected when the composite plastic outer layer 2 is formed, the first plastic body 20 is pressed on the outer pipe surface of the steel pipe matrix 1 by using a jig after centering, two ends of the first plastic body 20 are correspondingly pressed on the original pipe end paper winding position, meanwhile, the top surface of an anchor post 23 in the annular blind groove 22 is tightly attached to the surface of the vacuum glue-dipped fiber cloth 24 and pressed, and the vacuum glue-dipped fiber cloth 24 is integrally buried in the first plastic body 20.

In order to facilitate the loading operation of the first plastic body 20, in different embodiments, a flared guiding structure for facilitating the loading of the steel pipe base body 1 may be formed on the end face of the first plastic body 20, where the flared guiding structure is a single-end or two-end excess structure, and may be sawed after the first plastic body 20 is assembled in place on the steel pipe base body.

Considering that the poor combination property between plastics and metal is mainly due to the fact that the performance difference between the plastics is large, after molding and cooling, the plastics can shrink greatly, and the thermal expansion coefficient between the plastics and the metal is remarkably poor, therefore, the steel pipe matrix 1 after the first plastic body 20 is assembled can be concentrically maintained by using the anchor posts 23, pressure glue injection is carried out, and double-component vulcanized silicone rubber (RTV-2 glue) is adopted for glue injection during the pressure glue injection, the proportion of the components of the type of vulcanized silicone rubber is rich in variation, one variety can obtain vulcanized products with various specifications, and the purposes of insulation, encapsulation, caulking, sealing, moisture resistance and shock resistance can be realized according to actual requirements; meanwhile, the double-component vulcanized silicone rubber can be vulcanized deeply to buffer external stress, and structural deformation caused by temperature change is filled through deformation, so that the shock resistance of the pipe body is further improved, and a heat-resistant and cold-resistant buffer area is formed. In addition, in order to optimize the above-mentioned use effect of the filling structure layer 21, improve the adhesion property of the filling structure layer 21 and the vacuum impregnation fiber cloth 24, improve the anchoring forming effect of the anchor posts 23, and improve the overall physical structural strength and impact resistance of the filling structure layer 21, the two-component vulcanized silicone rubber is further doped with 7-12% by mass of modified reinforcing fibers for physical modification, the modified reinforcing fibers are monofilament fibers modified by a silane coupling agent, the monofilament lengths of the monofilament fibers are 4-7 mm, the fineness is 1-1.5D, and the fiber types are the same as the base materials of the vacuum impregnation fiber cloth.

As an example, in the present embodiment, the gap between the sleeve pipe body of the first plastic body 20 and the steel pipe base body around which the vacuum glue-impregnated fiber cloth is wrapped is 0.4mm (the glue-injection gap, the glue-injection hole is reserved at the position corresponding to the glue-injection gap), and the gap between the bottom surface of the body of the annular blind groove 22 and the vacuum glue-impregnated fiber cloth 24 around which the surface of the steel pipe base body 1 is wrapped is 0.3 to 0.5mm. The corresponding bi-component vulcanized silicone rubber is prepared by taking alpha, omega-dihydroxyl polydimethylsiloxane as a base rubber, white carbon black as a reinforcing filler and dimethyl silicone oil as a plasticizer, adding a cross-linking agent, a tackifier and a catalyst, scraping off an overflow sizing material after injection molding, performing heat vulcanization treatment, and standing for 20min after the treatment is finished.

And (3) treating the treated pipe as a raw material by using a hot dip molding process to obtain a second plastic body 3, polishing the end after the treatment is finished, inspecting, sequentially performing electric spark leakage detection, delamination-preventing thickness detection, end-retaining inspection, peeling strength and other quality inspection items, and obtaining the finished plastic steel composite pipe after the inspection is qualified.

Under the technical conditions of the present embodiment, the corresponding first plastic body may be one of heat-resistant polyethylene, crosslinked polyethylene, polyurethane, alicyclic epoxy glass fiber reinforced plastic and polyimide glass fiber reinforced plastic, and the second plastic body may be one of polyethylene, epoxy resin and polyurethane. The plastic steel composite pipe after being molded has excellent corrosion resistance, structural strength, good electrical insulation and other excellent performances. The composite plastic outer layer 2 in the pipe body can bear larger external force without deformation in various applications due to the structural combination of the first plastic body 20 and the filling structural layer 21, and interlayer stripping failure between the first plastic body 20 and the steel pipe base body 1 due to temperature change and external force impact is less likely to occur, so that the composite plastic outer layer has better stability in a chemical corrosion environment; so that the pipe body can maintain stable performance and service life under various severe working environments and can be effectively improved.

In summary, the plastic steel composite pipe of the embodiment has the characteristics of excellent high temperature resistance, high pressure resistance, oil resistance, corrosion resistance, temperature resistance, good structural stability and the like, so that the plastic steel composite pipe can play a role in urban tap water pipe network systems, building water supply and drainage, gas and ground radiation heating systems, industrial fluid conveying fields, agricultural irrigation pipelines, post and telecommunication lines and electric wire protective sleeves, and has wider application fields.

The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (9)

1. The plastic steel composite pipe is characterized by comprising a steel pipe matrix, wherein the outer surface of the steel pipe matrix is wrapped with vacuum glue-dipped fiber cloth, and a composite plastic material outer layer is formed on the outer pipe surface of the steel pipe matrix wrapped with the vacuum glue-dipped fiber cloth;

The composite plastic outer layer comprises a first plastic body, the first plastic body is of a prefabricated sleeve structure, the sleeve thickness of the first plastic body is 1/3-1/2 of the sleeve thickness of the steel pipe matrix, and the first plastic body is concentrically sleeved on the outer pipe surface of the steel pipe matrix; the inner side of the first plastic body is provided with a plurality of annular blind grooves at intervals along the length direction of the pipe body, the annular blind grooves adjacent to each other in position are reserved with communication parts at the joint sides corresponding to the steel pipe base body, and anchor columns arranged in an array are formed in the annular blind grooves;

A glue injection gap is reserved between the sleeve pipe body of the first plastic body and the steel pipe matrix wrapped with the vacuum glue-dipped fiber cloth, and the top surface of the anchor post is tightly pressed on the surface of the vacuum glue-dipped fiber cloth of the steel pipe matrix;

The gap space between the first plastic body and the steel pipe matrix takes vulcanized silicone rubber as a filling structure layer, and modified reinforcing fibers with the mass ratio of 7-12% are further doped in the filling structure layer;

the plastic steel composite pipe is characterized in that a second plastic body is further formed on the inner pipe surface of the steel pipe substrate and the outer pipe surface of the first plastic body, the second plastic body is a film material with the thickness of 0.2-0.3 mm, and the second plastic body is formed on the surface structure through a spin coating process or a hot dip molding process.

2. The plastic steel composite pipe according to claim 1, wherein the steel pipe substrate is a galvanized welded steel pipe or a galvanized seamless steel pipe or a spiral steel pipe subjected to surface polishing treatment.

3. The plastic steel composite pipe of claim 1, wherein the first plastic body is formed with a flared guide structure on an end surface for facilitating loading of the steel pipe substrate, the flared guide structure being a residual structure, and the first plastic body is sawed out after being assembled in place on the steel pipe substrate.

4. The plastic steel composite pipe according to claim 1, wherein the sum of the lengths of the annular blind grooves formed on the first plastic body is 75% -85% of the whole length of the pipe, and the length-diameter ratio of each annular blind groove is 3:1-5:1; and the gap between the corresponding ring surface of the bottom of the annular blind groove and the surface of the steel pipe matrix wrapped with the vacuum glue-dipped fiber cloth is 1/5-1/3 of the pipe thickness of the first plastic sleeve.

5. The plastic steel composite pipe according to claim 1, wherein the communicating part is a plurality of connecting channels formed between adjacent annular blind grooves, an annular inward neck structure attached to the steel pipe base body side or formed on the side wall between adjacent annular blind grooves, and the connecting channels are uniformly arranged on the corresponding annular surfaces; the projection size of the communication part on the radial section of the plastic steel composite pipe is 20-30% of the projection size of the annular blind groove on the radial section of the plastic steel composite pipe.

6. The plastic steel composite pipe according to claim 1, wherein the cross section of the anchor post is cross-shaped or circular; the area of the anchor post in the setting plane of the annular blind groove is 7-15%.

7. The plastic steel composite pipe according to claim 1, wherein the base material of the vacuum glue dipped fiber cloth is glass fiber cloth or aramid fiber cloth or carbon fiber cloth modified by a silane coupling agent; the modified reinforcing fiber is a monofilament fiber modified by a silane coupling agent, the monofilament length of the monofilament fiber is 4-7 mm, the fineness is 1-1.5D, and the fiber type is the same as the base material of the vacuum glue-dipped fiber cloth.

8. The plastic steel composite pipe of claim 1, wherein the filler structural layer is an integrally molded structure of unitary injection.

9. A method for preparing a plastic steel composite pipe, which is used for preparing the plastic steel composite pipe in claim 1, and specifically comprises the following operation steps:

S1, cleaning the surface of a steel pipe matrix, and respectively carrying out rust removal and dust removal on the inner surface and the outer surface of the steel pipe matrix; spraying a silane coupling agent on the surface of the steel pipe matrix after the rust removal and dust removal treatment is finished, standing at room temperature, placing the steel pipe matrix in a baking oven after the surface is dried, baking the steel pipe matrix for 30 to 50 minutes at the temperature of 40 to 60 ℃, and naturally cooling the steel pipe matrix;

s2, carrying out pipe end wrapping on the cooled steel pipe matrix; then wrapping vacuum glue-dipped fiber cloth on the surface of the steel pipe matrix after the pipe end is wrapped, taking the pipe end wrapping paper at two ends of the steel pipe matrix as a boundary when wrapping the vacuum glue-dipped fiber cloth, and removing the pipe end wrapping paper after the wrapping of the vacuum glue-dipped fiber cloth is completed;

s3, selecting a first plastic body matched with the size of the steel pipe matrix, and sleeving one end of the steel pipe matrix, wherein the outer side of the first plastic body is pressed on the paper winding position of the original pipe end in a pressing mode, so that the vacuum glue-dipped fiber cloth area is buried in the first plastic body;

S4, taking vulcanized silicone rubber as a raw material, performing pressure injection from a reserved injection hole position on the first plastic body to enable the vulcanized silicone rubber to fill a gap space between the first plastic body and the steel pipe matrix, then scraping off excessive sizing material, and performing heat vulcanization treatment;

And S5, treating the pipe treated in the step S4 by using a spin coating process or a hot dip molding process to obtain a second plastic body, polishing the end after the treatment is finished, and obtaining the finished plastic steel composite pipe after the detection is qualified.