Nodular cast iron pipe product based on composite material outer spray paint and manufacturing process

Abstract

The invention belongs to the technical field of nodular cast iron pipe machining, and particularly relates to a nodular cast iron pipe product based on composite material outer spray paint and a manufacturing process. The manufacturing process comprises the following steps that S1, thermal refining, inoculation and spheroidizing are conducted on molten metal; s2, casting of molten metal and cooling of the nodular cast iron pipe; s3, annealing heat treatment; s4, shot blasting treatment is conducted on the outer wall of the nodular cast iron pipe; and S5, the outer wall is subjected to two-layer cross winding with the included angle of + / -50-70 degrees with the straight section of the pipe body, and finally, after one-layer annular winding perpendicular to the straight section of the pipe body is conducted, outer surface resin curing, lining layer coating and paint spraying are conducted. According to the method, the anti-corrosion treatment is carried out twice, the service life of a cast pipe product under the severe condition is guaranteed through multi-coating anti-corrosion, the service life of the cast pipe is prolonged, and consumption of steel resources is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ductile iron pipe processing, in particular to a composite material-based externally spray-painted ductile iron pipe product and a manufacturing process. Background Art

[0002] Ductile iron pipe is a major type of cast iron alloy pipe. It possesses the physical and chemical properties of conventional cast iron alloys, but boasts mechanical properties similar to those of steel pipe. Under an optical microscope, the typical metallographic structure of ductile iron pipe after annealing heat treatment is: a large amount of ferrite (F), graphite (G), and a small amount of pearlite (P). It offers excellent mechanical and mechanical properties, superior corrosion resistance, excellent ductility, excellent sealing, and simple installation, making it widely used in the manufacturing industry for the supply and transportation of conventional gases and liquids.

[0003] Existing ductile iron pipes require high corrosion resistance due to their demanding performance. Currently, the pipe industry is seeing an emerging trend toward pipes made from polyester resin and glass fiber, molded using centrifugal casting or winding methods. Subsequent improvements have refined the manufacturing process for this type of pipe. Therefore, research into using highly corrosion-resistant ductile iron pipes while meeting pressure standards, thereby extending their service life, significantly conserves steel resources and fossil energy, and holds significant strategic significance. Summary of the Invention

[0004] 1. Technical problems to be solved

[0005] The purpose of the present invention is to solve the problem of how to extend the service life of ductile iron pipes in the prior art, and to propose a ductile iron pipe product and a manufacturing process based on composite material external spray painting.

[0006] 2. Technical solution

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A manufacturing process for ductile iron pipes based on composite material external spray painting comprises the following steps:

[0009] S1. Tempering, inoculation and spheroidizing of the molten metal: The molten metal and scrap steel are subjected to tempering treatment, and then poured into a spheroidizing treatment bag, TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant is added for inoculation, and the passivated granular magnesium spheroidizing agent is sprayed into the spheroidizing treatment bag by a blowing process to complete the spheroidizing treatment of the molten metal;

[0010] S2, casting of molten metal and cooling of ductile iron pipe: the molten metal that has been subjected to the quenching and tempering treatment, inoculation treatment and spheroidization treatment in step S1 is subjected to a second inoculation treatment by adding TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant simultaneously with the flow of the molten metal during the casting process, and then cast into a tube blank in a centrifuge. After the tube mold is rotated for a period of time, the outer wall of the tube mold is cooled by cooling water. When the tube blank is cooled to a temperature within the range of 500° C.-600° C. in the tube mold, it is pulled out of the tube mold and transported to the front of the annealing heat treatment furnace;

[0011] S3, annealing heat treatment: sending the tube blank in step S3 into an annealing furnace for annealing heat treatment;

[0012] S4. Shot blasting the outer wall of the ductile iron pipe to increase the surface area of ​​the outer wall and increase the bonding strength between the resin winding layer and the substrate;

[0013] S5. Wrap the outer wall with two layers of cross winding at an angle of ±50°-70° with the straight section of the pipe body, and finally wrap it with one layer of annular winding perpendicular to the straight section of the pipe body, then cure the outer surface resin, and apply and spray paint the inner lining.

[0014] Preferably, in S1, molten metal having a mass fraction in the range of 80wt%-90wt% and a temperature in the range of 1440°C-1460°C and 10wt%-20wt% of scrap steel are used for tempering treatment.

[0015] Preferably, the mass fraction of the TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant in S1 is in the range of 2.51wt%-3.73wt%.

[0016] Preferably, during the S2 casting process, the temperature of the molten metal is maintained within the range of 1340°C-1420°C.

[0017] Preferably, the mass fraction of the TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant in S2 is in the range of 0.2wt%-0.8wt% and the particle size is in the range of 0.2mm-2mm.

[0018] Preferably, the rotation speed of the tube mold in S2 is in the range of 750 r / min-1000 r / min, and the rotation time is in the range of 0.3 min to 4 min.

[0019] Preferably, the specific steps of the annealing heat treatment in S3 are: heating the tube blank not exceeding 500°C to a temperature of 820°C-850°C within a time range of 5min-15min, maintaining the temperature at 820°C-850°C within a holding time range of 15min-25min, and slowly cooling the temperature within the range of 820°C-850°C to below 700°C within a time range of 15min-20min.

[0020] Preferably, the specific steps of the shot blasting treatment in S4 are: using a grinder and a shot blasting machine to perform shot blasting on the outer wall, and after the ductile iron pipe ensures the size requirements, the outer wall surface has no obvious casting defects, has a silver-gray metallic luster, is completely roughened, and the roughness reaches R40-60μm. The microscopic surface is a fine concave-convex surface, and the cleanliness level reaches Sa2.5.

[0021] The present invention also provides a ductile iron pipe product produced by the above manufacturing process.

[0022] 3. Beneficial effects

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] (1) In the present invention, the anti-corrosion treatment is carried out twice and multi-coating anti-corrosion is used to ensure the service life of the cast pipe product under harsh conditions, thereby extending the service life of the cast pipe and significantly reducing the consumption of steel resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a schematic flow chart of a manufacturing process of ductile iron pipes based on composite material external spray painting proposed by the present invention. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0027] Example 1:

[0028] Reference Figure 1 A manufacturing process for ductile iron pipes based on composite material external spray painting comprises the following steps:

[0029] S1. Tempering, inoculation and spheroidizing of the molten metal: The molten metal and scrap steel are subjected to tempering treatment, and then poured into a spheroidizing treatment bag, TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant is added for inoculation, and the passivated granular magnesium spheroidizing agent is sprayed into the spheroidizing treatment bag by a blowing process to complete the spheroidizing treatment of the molten metal;

[0030] S2, casting of molten metal and cooling of ductile iron pipe: the molten metal that has been subjected to the quenching and tempering treatment, inoculation treatment and spheroidization treatment in step S1 is subjected to a second inoculation treatment by adding TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant simultaneously with the flow of the molten metal during the casting process, and then cast into a tube blank in a centrifuge. After the tube mold is rotated for a period of time, the outer wall of the tube mold is cooled by cooling water. When the tube blank is cooled to a temperature within the range of 500° C.-600° C. in the tube mold, it is pulled out of the tube mold and transported to the front of the annealing heat treatment furnace;

[0031] S3, annealing heat treatment: sending the tube blank in step S3 into an annealing furnace for annealing heat treatment;

[0032] S4. Shot blasting the outer wall of the ductile iron pipe to increase the surface area of ​​the outer wall and increase the bonding strength between the resin winding layer and the substrate;

[0033] S5. Wrap the outer wall with two layers of cross winding at an angle of ±50°-70° with the straight section of the pipe body, and finally wrap it with one layer of annular winding perpendicular to the straight section of the pipe body, then cure the outer surface resin, and apply and spray paint the inner lining.

[0034] In this embodiment, the anti-corrosion treatment is carried out twice and multi-coating anti-corrosion is used to ensure the service life of the cast pipe product under harsh conditions, thereby extending the service life of the cast pipe and significantly reducing the consumption of steel resources.

[0035] Example 2:

[0036] In this embodiment, a manufacturing process for ductile iron pipes based on composite material external spray painting includes the following steps:

[0037] S1, tempering, inoculation and spheroidizing of the molten metal: molten metal and scrap steel are subjected to tempering treatment, then poured into a spheroidizing treatment bag, TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant is added for inoculation, and a passivated granular magnesium spheroidizing agent is sprayed into the spheroidizing treatment bag using a blowing process to complete the spheroidizing treatment of the molten metal, wherein in S1, molten metal having a mass fraction in the range of 80wt%-90wt% and a temperature in the range of 1440°C-1460°C and 10wt%-20wt% of scrap steel are subjected to tempering treatment, and the mass fraction of the TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant in S1 is in the range of 2.51wt%-3.73wt%;

[0038] S2, casting of molten metal and cooling of ductile iron pipe: the molten metal which has been subjected to quenching and tempering treatment, inoculation treatment and spheroidizing treatment in step S1 is subjected to re-inoculation treatment by adding TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant synchronously with the inflow of the molten metal during the casting process, and then cast into a tube blank in a centrifuge. After the tube die is rotated for a period of time, the outer wall of the tube die is cooled by cooling water. When the tube blank is cooled to a temperature within the range of 500°C-600°C in the tube die, it is pulled out of the tube die and transported to an annealing heat treatment furnace. During the casting process, the temperature of the molten metal is maintained within the range of 1340°C-1420°C, the mass fraction of the TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant is within the range of 0.2wt%-0.8wt% and the particle size is within the range of 0.2mm-2mm, the rotation speed of the tube die is within the range of 750r / min-1000r / min, and the rotation time is within the range of 0.3min-4min;

[0039] S3, annealing heat treatment: sending the tube blank in step S3 into an annealing furnace for annealing heat treatment;

[0040] S4. Shot blasting the outer wall of the ductile iron pipe to increase the surface area of ​​the outer wall and increase the bonding strength between the resin winding layer and the substrate;

[0041] S5. Wrap the outer wall with two layers of cross winding at an angle of ±50°-70° with the straight section of the pipe body, and finally wrap it with one layer of annular winding perpendicular to the straight section of the pipe body, then cure the outer surface resin, and apply and spray paint the inner lining.

[0042] Example 3:

[0043] In this embodiment, a manufacturing process for ductile iron pipes based on composite material external spray painting includes the following steps:

[0044] S1. Tempering, inoculation and spheroidizing of the molten metal: molten metal with a mass fraction in the range of 80wt%-90wt% and a temperature in the range of 1440°C-1460°C and 10wt%-20wt% of scrap steel is tempered and then poured into a spheroidizing bag. A TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant with a mass fraction in the range of 2.51wt%-3.73wt% is added for inoculation. A passivated granular magnesium spheroidizing agent (mainly composed of Mg) is sprayed into the spheroidizing bag using a blowing process to complete the spheroidizing treatment of the molten metal.

[0045] S2, casting of molten metal and cooling of ductile iron pipe: the molten metal that has undergone quenching and tempering treatment, inoculation treatment and spheroidization treatment in step S1 is maintained at a temperature within the range of 1340°C-1420°C, and a TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant with a mass fraction within the range of 0.2wt%-0.8wt% and a particle size within the range of 0.2mm-2mm is added simultaneously with the inflow of the molten metal during the casting process for re-inoculation treatment, and then cast into a centrifuge tube blank, and then the tube mold is rotated at a speed within the range of 750r / min-1000r / min for a time within the range of 0.3min-4min, and then the outer wall of the tube mold is cooled by cooling water. When the tube blank is cooled in the tube mold to a temperature within the range of 500°C-600°C, it is pulled out of the tube mold and transported to the front of the annealing heat treatment furnace;

[0046] S3, annealing heat treatment: the tube blanks in step S3 are fed into an annealing furnace for annealing heat treatment, heating the tube blanks (not exceeding 500° C.) to a temperature of 820° C.-850° C. for a time period of 5-15 minutes, maintaining the temperature at 820° C.-850° C. for a holding time of 15-25 minutes, and slowly cooling the temperature from 820° C.-850° C. to below 700° C. for a time period of 15-20 minutes;

[0047] S4. Shot blast the outer wall of the ductile iron pipe to increase the outer wall surface area and strengthen the bonding strength between the resin wrapping layer and the substrate. Use a grinder and a shot blasting machine to shot blast the outer wall. After the ductile iron pipe meets the dimensional requirements, the outer wall surface has no obvious casting defects, has a silver-gray metallic luster, is completely roughened, and has a roughness of R40-60μm. The microscopic surface has a fine concave and convex surface, and reaches the cleanliness level of Sa2.5.

[0048] S5. Wrap the outer wall with two layers of cross winding at an angle of ±50°-70° with the straight section of the pipe body, and finally wrap it with one layer of annular winding perpendicular to the straight section of the pipe body, then cure the outer surface resin, and apply and spray paint the inner lining.

[0049] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A manufacturing process for ductile iron pipes based on composite material external spray painting, characterized in that: The following steps are involved: S1. Tempering, inoculation and spheroidizing of the molten metal: the molten metal and scrap steel are subjected to tempering treatment, and then poured into a spheroidizing bag, TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant is added for inoculation treatment, and the passivated granular magnesium spheroidizing agent is sprayed into the spheroidizing bag by a spraying process to complete the spheroidizing treatment of the molten metal; S2, casting of molten metal and cooling of ductile iron pipe: the molten metal which has been subjected to quenching and tempering treatment, inoculation treatment and spheroidization treatment in step S1 is inoculated again by adding TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant during the casting process as the molten metal flows in, and then cast into the centrifuge tube blank, and then after the tube mold rotates for a period of time, the outer wall of the tube mold is cooled by cooling water, and when the tube blank is cooled in the tube mold to a temperature within the range of 500°C-600°C, it is pulled out of the tube mold and transported to the front of the annealing heat treatment furnace; S3, annealing heat treatment: sending the tube blank in step S3 into an annealing furnace for annealing heat treatment; S4, performing shot blasting on the outer wall of the ductile iron pipe to increase the surface area of ​​the outer wall and increase the bonding force between the resin winding layer and the substrate; S5. Carry out 2 layers of cross winding on the outer wall at an angle of ±50°-70° with the straight section of the pipe body, and finally carry out 1 layer of annular winding perpendicular to the straight section of the pipe body, then cure the outer surface resin, and coat and spray the inner lining.

2. The manufacturing process of ductile iron pipe based on composite material external spray painting according to claim 1 is characterized in that: In the S1, molten metal having a mass fraction in the range of 80wt%-90wt% and a temperature in the range of 1440°C-1460°C and 10wt%-20wt% of scrap steel are used for tempering treatment.

3. The manufacturing process of ductile iron pipe based on composite material external spray painting according to claim 2 is characterized in that: The mass fraction of the TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant in the S1 is in the range of 2.51wt%-3.73wt%.

4. The manufacturing process of ductile iron pipe based on composite material external spray painting according to claim 1 is characterized in that: During the S2 casting process, the temperature of the molten metal is maintained within the range of 1340°C-1420°C.

5. The manufacturing process of ductile iron pipe based on composite material external spray painting according to claim 4 is characterized in that: The mass fraction of TFeSi75 ferrosilicon alloy or silicon-barium-calcium alloy inoculant in S2 is in the range of 0.2wt%-0.8wt% and the particle size is in the range of 0.2mm-2mm.

6. The manufacturing process of ductile iron pipe based on composite material external spray painting according to claim 5 is characterized in that: The rotation speed of the tube mold in S2 is in the range of 750r / min-1000r / min, and the rotation time is in the range of 0.3min-4min.

7. The manufacturing process of ductile iron pipe based on composite material external spray painting according to claim 1 is characterized in that: The specific steps of the annealing heat treatment in S3 are: heating the tube blank not exceeding 500°C to a temperature of 820°C-850°C within a time range of 5min-15min, maintaining the temperature at 820°C-850°C within a holding time range of 15min-25min, and reducing the temperature within the range of 820°C-850°C to below 700°C within a slow cooling time range of 15min-20min.

8. The manufacturing process of ductile iron pipe based on composite material external spray painting according to claim 1 is characterized in that: The specific steps of the shot blasting treatment in S4 are: use a grinder and a shot blasting machine to perform shot blasting on the outer wall. After the ductile iron pipe meets the size requirements, the outer wall surface has no obvious casting defects, has a silver-gray metallic luster, is completely roughened, and the roughness reaches R40-60μm. The microscopic surface is a fine concave-convex surface, reaching the cleanliness level Sa2.

5.

9. A ductile iron pipe product produced by the manufacturing process according to any one of claims 1 to 8.

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