Production method and production device of plastic steel pipe

Abstract

The invention relates to a production method and a production device of a plastic steel pipe, and the method comprises the following steps: carrying out plastic film pipe heating, plastic film pipe expanding, plastic film shaping after pipe expanding, pipe sleeving and plastic packaging, and carrying out plastic packaging on the surface of the steel pipe to form a layer of plastic film pipe. The steel pipe is tightly combined with the plastic film, the temperature change does not influence the combination degree of the steel pipe and the plastic film, the plastic film protection layer does not fall off or be separated from the steel pipe, the anti-corrosion effect is achieved, and the plastic film can serve as an anti-corrosion layer of the heat exchange pipe. The thickness of the plastic film can be 0.05 mm-5 mm. The invention also has the advantages of simple production and low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of film coating, and in particular relates to a production method and a production device for a plastic steel pipe. Background Art

[0002] At present, in order to prevent steel pipes from corroding in the use environment, plastic spraying technology is often used to coat plastic paint or powder on the surface of the steel pipe to form a protective layer or decorative layer. However, in a high temperature environment, especially when the temperature difference changes greatly, the protective layer is easy to fall off or separate from the steel pipe due to thermal expansion and contraction, thus losing its anti-corrosion effect and cannot be used as an anti-corrosion layer for heat exchange tubes. Summary of the Invention

[0003] The purpose of the invention is to solve the problem of loose bonding between the coating and the surface of the steel pipe in the background art, and to provide a method and a device for producing plastic steel pipes. The present invention can seal a layer of plastic film on the outer surface of the steel pipe, and the steel pipe and the plastic film are tightly bonded. Temperature changes do not affect the bonding between the steel pipe and the plastic film. The plastic material can be selected from polyester, fluoroplastics or polyolefins, etc., and the thickness of the plastic film can be 0.05mm-5mm. The type of plastic and the thickness of the plastic film can be adjusted according to demand. For example, fluoroplastics can be used in a high-temperature corrosive environment. If a good heat exchange effect is required, the thickness of the plastic film can be small. It also has the advantages of simple production and low cost.

[0004] The technical solution of the present invention: A method for producing a plastic-steel pipe comprises the following steps: Step 1: Heating process: The processed plastic film tube is injected into the heating unit in the flow channel of the plastic film tube, and heated by the inner cavity of the heating unit. Different heating temperatures are set according to different plastic materials. Step 2, tube expansion process: the heated plastic film tube enters the tube expansion unit in the plastic film tube flow channel for continuous tube expansion; Step 3: Shaping process: After tube expansion, the plastic film tube continuously enters the shaping unit for rapid cooling and shaping, so that the plastic film tube remains in the expanded state; Step 4: Casing process: The plastic film tube in the expanded state is inserted from one end of the casing unit, and the steel pipe is inserted from the other end of the casing unit to complete the casing process and obtain a semi-finished product; Step 5: Plastic sealing process: The semi-finished product enters the plastic sealing unit. In the plastic sealing unit, a vacuum is drawn between the steel pipe and the plastic film tube, and the outside of the plastic film tube is heated. The plastic film tube shrinks after heating and plastic sealing and is tightly combined with the steel pipe to obtain a finished product.

[0005] The outside of the plastic film tube is heated by hot air on the outside of the semi-finished product, and the plastic film is tightly sealed on the steel tube; the hot air temperature is 200~380℃ for fluoroplastics, 70~190℃ for polyesters, and 70~120℃ for polyolefins.

[0006] A production device for plastic-steel pipes, comprising a heating unit, a pipe expansion unit, a shaping unit, a casing unit, and a plastic sealing unit, wherein the heating unit, the pipe expansion unit, the shaping unit, the casing unit, and the plastic sealing unit are provided with a double-cavity structure, comprising an inner cavity and an outer cavity, wherein the inner cavity is a flow channel for the plastic film pipe; The heating unit comprises a heating unit inner cavity, a heating unit outer cavity and a heating medium inlet, wherein the heating medium inlet is communicated with the heating unit outer cavity; The tube expansion unit comprises an inner cavity, an outer cavity and a vacuum port, and a plurality of first through holes are formed on the tube wall between the inner cavity and the outer cavity. The shaping unit comprises a shaping unit inner cavity and a shaping unit outer cavity; a shaping unit cooling water inlet is provided on one side of the shaping unit outer cavity, and a shaping unit cooling water outlet is provided on the other side of the shaping unit outer cavity; The sleeve unit has an inner cavity and an outer cavity, the outer cavity has a vacuum pumping hole, and a plurality of second through holes are opened on the tube wall between the inner cavity and the outer cavity. The plastic sealing unit has a plastic sealing unit inner cavity and a plastic sealing unit outer cavity, the plastic sealing unit outer cavity is provided with a plastic sealing unit hot air inlet, and a plurality of hot air through holes are provided on the pipe wall between the plastic sealing unit inner cavity and the plastic sealing unit outer cavity; The outer cavity of the heating unit is a heating chamber, the outer cavity of the tube expansion unit is a vacuum chamber, the outer cavity of the shaping unit is a cooling chamber, the outer cavity of the casing unit is a vacuum chamber, and the outer cavity of the plastic sealing unit is a heating chamber. The plastic film tube passes continuously in the plastic film tube flow channel, and heating, tube expansion, shaping, casing and plastic sealing are realized in sequence.

[0007] The outer cavity of the heating unit is heated by graphene, glycerin or silicone oil.

[0008] The diameter of the inner cavity of the tube expansion unit is 5% to 20% larger than the diameter of the plastic film tube. The pressure inside the plastic film tube is greater than the pressure outside the tube, thereby achieving expansion of the plastic film tube.

[0009] The temperature of the cooling water in the outer cavity of the shaping unit is 5°C to 10°C.

[0010] The inner cavity of the casing unit is the casing channel, and the outer cavity of the casing unit is the vacuum chamber. Several second through holes on the tube wall between the inner cavity of the casing unit and the outer cavity of the casing unit keep the plastic film tube in an expanded state and adsorbed on the inner cavity wall. After the steel pipe is completely penetrated from the other end, the vacuum is destroyed and the casing is completed.

[0011] The outer cavity of the plastic sealing unit is a heating chamber, the inner cavity of the plastic sealing unit is a semi-finished product channel, and a plurality of hot air holes are opened on the pipe wall between the inner cavity of the plastic sealing unit and the outer cavity of the plastic sealing unit.

[0012] Beneficial effects of the present invention: The present invention can seal a layer of plastic film on the outer surface of a steel pipe. The steel pipe and the plastic film are tightly bonded, and temperature changes do not affect the bonding between the steel pipe and the plastic film. The plastic film protective layer will not fall off or separate from the steel pipe, thereby playing an anti-corrosion role. The plastic film can be used as an anti-corrosion layer for heat exchange tubes. The material of the plastic film can be selected from polyester, fluoroplastics, or polyolefins, and the thickness of the plastic film can be 0.05mm-5mm. The type of plastic and the thickness of the plastic film can be adjusted according to needs. For example, fluoroplastics can be used in high-temperature corrosive environments. If a good heat exchange effect is required, a smaller plastic film thickness is sufficient. The invention also has the advantages of simple production and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of a production device of the present invention. DETAILED DESCRIPTION

[0014] like Figure 1 As shown, a method for producing a plastic steel pipe comprises the following steps: Step 1, heating process: the processed plastic film tube is injected into the heating unit B1 in the plastic film tube flow channel 1, and is heated by the inner cavity 4 of the heating unit. Different heating temperatures are set according to different plastic materials. Step 2, tube expansion process: the heated plastic film tube enters the tube expansion unit B2 in the plastic film tube flow channel 1 for continuous tube expansion; Step 3: Shaping process: After tube expansion, the plastic film tube continuously enters the shaping unit B3 for rapid cooling and shaping, so that the plastic film tube remains in the expanded state; Step 4: Casing process: The expanded plastic film tube enters from one end of the casing unit B4, and the steel pipe enters from the other end of the casing unit B4, completing the casing process and obtaining a semi-finished product; Step 5: Plastic sealing process: The semi-finished product enters the plastic sealing unit B5. In the plastic sealing unit B5, a vacuum is drawn between the steel pipe and the plastic film tube, and the outside of the plastic film tube is heated. The plastic film tube shrinks after heating and plastic sealing, and is tightly combined with the steel pipe to obtain a finished product.

[0015] The outside of the plastic film tube is heated by hot air on the outside of the semi-finished product, and the plastic film is tightly sealed on the steel tube; the hot air temperature is 200~380℃ for fluoroplastics, 70~190℃ for polyesters, and 70~120℃ for polyolefins.

[0016] A production device for plastic-steel pipes, comprising a heating unit B1, a pipe expansion unit B2, a shaping unit B3, a sleeve unit B4, and a plastic sealing unit B5. The heating unit B1, the pipe expansion unit B2, the shaping unit B3, the sleeve unit B4, and the plastic sealing unit B5 are provided with a double-cavity structure, comprising an inner cavity and an outer cavity, wherein the inner cavity is a flow channel 1 for the plastic film pipe; The heating unit B1 has a heating unit inner cavity 4, a heating unit outer cavity 2 and a heating medium inlet 3, and the heating medium inlet 3 is connected to the heating unit outer cavity 2; The tube expansion unit B2 has an inner cavity 8, an outer cavity 5, and a vacuum port 6. A plurality of first through holes 7 are formed on the tube wall between the inner cavity 8 and the outer cavity 5. The shaping unit B3 comprises a shaping unit inner cavity 11 and a shaping unit outer cavity 9; a shaping unit cooling water inlet 10 is provided on one side of the shaping unit outer cavity 9, and a shaping unit cooling water outlet 12 is provided on the other side of the shaping unit outer cavity 9; The sleeve unit B4 has a sleeve unit inner cavity 15 and a sleeve unit outer cavity 13. The sleeve unit outer cavity 13 has a sleeve unit vacuum extraction hole 14. A plurality of second through holes 16 are opened on the tube wall between the sleeve unit inner cavity 15 and the sleeve unit outer cavity 13. The plastic sealing unit B5 has a plastic sealing unit inner cavity 19 and a plastic sealing unit outer cavity 17. The plastic sealing unit outer cavity 17 is provided with a plastic sealing unit hot air inlet 18. A plurality of hot air holes 20 are provided on the tube wall between the plastic sealing unit inner cavity 19 and the plastic sealing unit outer cavity 17. The outer cavity 2 of the heating unit is a heating chamber, the outer cavity 5 of the tube expansion unit is a vacuum chamber, the outer cavity 9 of the shaping unit is a cooling chamber, the outer cavity 13 of the sleeve unit is a vacuum chamber, and the outer cavity 17 of the plastic sealing unit is a heating chamber. The plastic film tube passes continuously in the plastic film tube circulation channel 1, and heating, tube expansion, shaping, sleeve and plastic sealing molding are realized in sequence.

[0017] The outer cavity 2 of the heating unit is heated by graphene, glycerin or silicone oil.

[0018] The diameter of the inner cavity 8 of the tube expansion unit is 5% to 20% larger than the diameter of the plastic film tube. The pressure inside the plastic film tube is greater than the pressure outside the tube, thereby achieving expansion of the plastic film tube.

[0019] The temperature of the cooling water in the outer cavity 9 of the shaping unit is 5°C to 10°C.

[0020] The inner cavity 15 of the sleeve unit is the sleeve channel, and the outer cavity 13 of the sleeve unit is the vacuum chamber. Several second through holes 16 on the tube wall between the inner cavity 15 of the sleeve unit and the outer cavity 13 of the sleeve unit keep the plastic film tube in an expanded state and adsorbed on the inner cavity wall. After the steel pipe is completely penetrated from the other end, the vacuum is broken and the sleeve is completed.

[0021] The outer cavity 17 of the plastic sealing unit is a heating chamber, and the inner cavity 19 of the plastic sealing unit is a semi-finished product channel. A number of hot air holes 20 are opened on the tube wall between the inner cavity 19 of the plastic sealing unit and the outer cavity 17 of the plastic sealing unit. Vacuum is drawn between the steel tube and the plastic film tube, and the semi-finished products continuously pass through the plastic sealing unit B5.

Claims

1. A method for producing a plastic steel pipe, characterized in that: The following steps are involved: Step 1, heating process: the processed plastic film tube is injected into the heating unit (B1) in the plastic film tube flow channel (1), and heated by the inner cavity (4) of the heating unit; Step 2, tube expansion process: the heated plastic film tube enters the tube expansion unit (B2) in the plastic film tube flow channel (1) and is continuously expanded; Step 3: Shaping process: After tube expansion, the plastic film tube continuously enters the shaping unit (B3) for rapid cooling and shaping, so that the plastic film tube remains in the expanded state; Step 4: Casing process: The plastic film tube in the expanded state is inserted from one end of the casing unit (B4), and the steel pipe is inserted from the other end of the casing unit (B4), completing the casing process and obtaining a semi-finished product; Step 5: Plastic sealing process: The semi-finished product enters the plastic sealing unit (B5). In the plastic sealing unit (B5), a vacuum is drawn between the steel pipe and the plastic film tube, and the outside of the plastic film tube is heated. The plastic film tube shrinks after heating and plastic sealing, and is tightly combined with the steel pipe to obtain a finished product.

2. The method for producing a plastic-steel pipe according to claim 1, wherein: The outside of the plastic film tube is heated by hot air on the outside of the semi-finished product, and the plastic film is tightly sealed on the steel tube; the hot air temperature is 200~380℃ for fluoroplastics, 70~190℃ for polyesters, and 70~120℃ for polyolefins.

3. A production device for plastic steel pipes, characterized by: The invention comprises a heating unit (B1), a tube expansion unit (B2), a shaping unit (B3), a sleeve unit (B4) and a plastic sealing unit (B5); the heating unit (B1), the tube expansion unit (B2), the shaping unit (B3), the sleeve unit (B4) and the plastic sealing unit (B5) are provided with a double-cavity structure, which is divided into an inner cavity and an outer cavity, and the inner cavity is a plastic film tube flow channel (1); The heating unit (B1) comprises a heating unit inner cavity (4), a heating unit outer cavity (2) and a heating medium inlet (3), wherein the heating medium inlet (3) is in communication with the heating unit outer cavity (2); The tube expansion unit (B2) comprises an inner tube expansion unit cavity (8), an outer tube expansion unit cavity (5), and a vacuum exhaust port (6) for the tube expansion unit. A plurality of first through holes (7) are provided on the tube wall between the inner tube expansion unit cavity (8) and the outer tube expansion unit cavity (5). The shaping unit (B3) comprises a shaping unit inner cavity (11) and a shaping unit outer cavity (9); a shaping unit cooling water inlet (10) is provided on one side of the shaping unit outer cavity (9), and a shaping unit cooling water outlet (12) is provided on the other side of the shaping unit outer cavity (9); The sleeve unit (B4) has a sleeve unit inner cavity (15) and a sleeve unit outer cavity (13); the sleeve unit outer cavity (13) has a sleeve unit vacuum extraction hole (14); and a plurality of second through holes (16) are provided on the tube wall between the sleeve unit inner cavity (15) and the sleeve unit outer cavity (13); The plastic sealing unit (B5) has a plastic sealing unit inner cavity (19) and a plastic sealing unit outer cavity (17); the plastic sealing unit outer cavity (17) is provided with a plastic sealing unit hot air inlet (18); and a plurality of hot air through holes (20) are provided on the pipe wall between the plastic sealing unit inner cavity (19) and the plastic sealing unit outer cavity (17); The outer cavity (2) of the heating unit is a heating chamber, the outer cavity (5) of the tube expansion unit is a vacuum chamber, the outer cavity (9) of the shaping unit is a cooling chamber, the outer cavity (13) of the sleeve unit is a vacuum chamber, and the outer cavity (17) of the plastic sealing unit is a heating chamber. The plastic film tube passes continuously in the plastic film tube flow channel (1), and heating, tube expansion, shaping, sleeve and plastic sealing molding are realized in sequence.

4. The production device of a plastic steel pipe according to claim 3, characterized in that: The outer cavity (2) of the heating unit adopts graphene heating, glycerin heating or silicone oil heating.

5. The production device of a plastic steel pipe according to claim 3, characterized in that: The diameter of the inner cavity (8) of the expansion unit is 5% to 20% larger than the diameter of the plastic film tube, and the pressure inside the plastic film tube is greater than the pressure outside the tube, thereby achieving expansion of the plastic film tube; The temperature of the cooling water in the outer cavity (9) of the shaping unit is 5°C to 10°C; The inner cavity (15) of the sleeve unit is a sleeve channel, and the outer cavity (13) of the sleeve unit is a vacuum chamber. A plurality of second through holes (16) on the tube wall between the inner cavity (15) of the sleeve unit and the outer cavity (13) of the sleeve unit keep the plastic film tube in an expanded state and adsorbed on the inner cavity wall. After the steel pipe is completely penetrated from the other end, the vacuum is broken and the sleeve is completed. The outer cavity (17) of the plastic sealing unit is a heating chamber, and the inner cavity (19) of the plastic sealing unit is a channel for product A. A plurality of hot air holes (20) are provided on the pipe wall between the inner cavity (19) of the plastic sealing unit and the outer cavity (17) of the plastic sealing unit. A vacuum is drawn between the steel pipe and the plastic film pipe, and the semi-finished product continuously passes through the plastic sealing unit (B5).

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