A gas powered spin cooling system and cooling method for thermoplastic pipes

Abstract

The present invention discloses a gas-powered spin cooling system and cooling method for thermoplastic pipes, which belongs to the field of pipe inner wall cooling devices, including an extrusion molding device, a vacuum sizing box, a spin cooling device and an adaptive adjustment device; the spin cooling device includes a pull rod arranged in the thermoplastic pipe, a device body sleeved on the pull rod and an air intake pipe for introducing airflow into the device body; the device body includes an air intake seat fixedly connected to the pull rod, a rotating air hood rotating relative to the air intake seat, and a sealing end cover, the air intake seat, the rotating air hood and the sealing end cover are connected to each other to form a closed circular column; the air intake seat is rotatably connected to the rotating air hood; an air intake inlet is provided on the air intake seat, and an exhaust pipe is provided in the rotating air hood; the exhaust pipe is provided in a non-axial position in the rotating air hood. The present invention introduces compressed air into the interior of the pipe, so that the compressed air can be used as a power to rotate the device and the compressed air can be used as a medium to cool the inner wall of the pipe.

Description

Technical Field

[0001] The invention relates to the field of pipeline inner wall cooling devices, in particular to a gas powered spin cooling system and a cooling method for thermoplastic pipes. Background Art

[0002] During the thermoplastic pipe production process, after being extruded from the die, the pipe enters a vacuum sizing chamber, where negative pressure is applied to hold the pipe against the inner wall of the sizing sleeve while water mist cools the outer wall. Thermoplastic pipes have very low thermal conductivity. For example, the thermal conductivity of PVC is 0.14-0.16 W / (mK), while that of medium-carbon steel is 60-80 W / (mK), a difference of approximately 500 times. Therefore, for thick-walled thermoplastic pipes, the inner wall temperature takes an extremely long time to reach below the decomposition temperature. Since the processing temperature of PVC is far above its decomposition temperature, proper processing depends entirely on thermal stabilizers.

[0003] After thermoplastic pipes are extruded, temperature stability after cooling is also extremely important, mainly reflected in the following aspects:

[0004] 1. Dimensional stability

[0005] After extrusion, the internal structure of thermoplastic materials is in a relatively unstable state. If the temperature is unstable after cooling, the pipe will be subjected to uneven thermal stress during the cooling process.

[0006] 2. Performance stability

[0007] The molecular chain structure of thermoplastic materials gradually solidifies during the cooling process. When the temperature stabilizes after cooling, the molecular chains of the material are able to arrange themselves in a relatively orderly manner. This helps to ensure the stability of the pipe's mechanical properties, such as tensile strength and flexural strength. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a gas-powered spin cooling system and cooling method for thermoplastic pipes. By introducing compressed air into the interior of the pipe, the compressed air can be used as a power to rotate the device, and the compressed air can be used as a medium to cool the inner wall of the pipe. By controlling the opening of the electronically controlled proportional valve, the temperature of the inner wall of the thermoplastic pipe is ensured to be stably cooled to the expected temperature.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0010] A gas-powered spin cooling system for thermoplastic pipes, comprising an extrusion molding device, a vacuum sizing box arranged outside the extruded thermoplastic pipe, a spin cooling device arranged inside the extruded thermoplastic pipe, and an adaptive adjustment device for controlling the rotation speed of the spin cooling device;

[0011] The spin cooling device comprises a pull rod disposed in a thermoplastic tube, a device body sleeved on the pull rod, and an air intake pipe for introducing airflow into the device body; the device body comprises an air intake seat fixedly connected to the pull rod, a rotating air cover rotating relative to the air intake seat, and a sealing end cover, wherein the air intake seat, the rotating air cover, and the sealing end cover are interconnected to form a closed circular column; the air intake seat is rotatably connected to the rotating air cover;

[0012] An air inlet is provided on the air inlet seat, and an exhaust pipe is provided in the rotating air hood; the exhaust pipe is provided in a non-axial position in the rotating air hood;

[0013] The self-adaptive adjustment device includes an electronically controlled proportional valve connected to the starting end of the intake pipe, a centralized control unit for controlling the opening of the electronically controlled proportional valve, and an infrared temperature sensor arranged at the starting end of the pull rod.

[0014] A further improvement of the technical solution of the present invention is that: the air intake seat includes an annular end face, a connecting pipe arranged on the inner circle of the end face and an outer edge arranged on the outer circle of the end face; an air intake inlet is arranged on the end face of the air intake seat; the air intake inlet is connected to the air intake pipeline; the connecting pipe is fixedly connected to the pull rod; the upper surface of the outer edge is sequentially provided with grooves and protrusions, and an elastic retaining ring is provided on the groove.

[0015] A further improvement of the technical solution of the present invention is that: the rotating air hood includes a cylindrical body, a first inner edge arranged at the front end of the cylindrical body and a second inner edge arranged at the rear end of the cylindrical body; an exhaust pipe is arranged inside the cylindrical body; the first inner edge is clamped between the elastic retaining ring and the protrusion; the inner diameter of the first inner edge is larger than the outer diameter of the outer edge, and the rotating air hood can rotate relative to the air inlet seat; a sealing member is arranged in the rotating air hood, and the sealing member is a conical elastic shell-shaped member; one end of the sealing member is fixed to the air inlet seat by a screw, and the other end is against the first inner edge of the rotating air hood.

[0016] A further improvement of the technical solution of the present invention is that: the sealing end cover is fixed to the second inner edge of the rotating air hood by screws; and a sealing ring is provided between the end of the sealing end cover and the connecting pipe.

[0017] A further improvement of the technical solution of the present invention is that the inlet of the exhaust pipe is arranged on the circular diameter of the cross section of the cylindrical body, the distance from the center of the circle is greater than 3 / 4 of the radius, and the exhaust pipe outlet is arranged on the cylindrical body.

[0018] A further improvement of the technical solution of the present invention is that the extrusion molding device includes an extrusion die arranged outside the unextruded thermoplastic pipe and an extrusion core die arranged outside the unextruded thermoplastic pipe.

[0019] A further improvement of the technical solution of the present invention is that: the vacuum sizing box is cylindrical, and a plurality of cooling water sprays are provided on the inner wall.

[0020] The further improvement of the technical solution of the present invention is that: the data transmission mode of the infrared temperature sensor is wireless transmission; the centralized control unit is externally connected to a wireless receiving transmitter; the electric controlled proportional valve is provided with an air source inlet, which is externally connected to an air source.

[0021] A method for gas-powered spin cooling of thermoplastic pipes, comprising the following steps:

[0022] S1. The thermoplastic pipe passes through the extrusion molding device and enters the vacuum sizing box after extrusion. The vacuum sizing box uses negative pressure to adsorb the pipe to the inner wall of the sizing sleeve and move it forward. At the same time, cooling water spray cools the outer wall of the pipe.

[0023] S2, infrared temperature sensor collects the starting section of the thermoplastic pipe after extrusion, measures the inner wall temperature in real time and transmits it to the centralized control unit;

[0024] S3. The centralized control unit controls the flow rate of the airflow in the intake pipe by adjusting the opening of the electronically controlled proportional valve. Then, when the test point moves to the rotary cooling device, the centralized control unit controls the opening of the electronically controlled proportional valve so that the rotary cooling device outputs a corresponding rotation speed.

[0025] A further improvement of the technical solution of the present invention is that the centralized control unit in S3 controls the flow rate of the airflow in the intake pipe by adjusting the opening of the electronically controlled proportional valve, which specifically includes the following steps:

[0026] S31 When the temperature change slope K collected by the centralized control unit within the preset time period is in [-K1, K1] and is the same in sign, the centralized control unit takes the average temperature T within the preset time period a , and calculate the opening D of the electronically controlled proportional valve:

[0027] D=A×(T a -T e ）

[0028] Among them, A is the proportional coefficient, T e is the desired temperature, K1 is the first slope, ranging from 0.1 to 0.5;

[0029] S32 When the temperature change slope K collected by the centralized control unit within the preset time period is in [-K1, K1] and the positive and negative are different, or the minimum value of K is in [-K2, -K1) or the maximum value of K is in (K1, K2], the opening D of the electronically controlled proportional valve is calculated by the PID control method:

[0030]

[0031] Where Kp is the proportional gain, Ki is the integral gain, Kd is the differential gain, T is the real-time temperature, t is the preset time, and K2 is the second slope, ranging from 0.8 to 1;

[0032] S33: When the minimum value of the temperature change slope K within the preset time period collected by the centralized control unit is [-K3, K2) or the maximum value of K is (K2, K3), the production of the thermoplastic pipe is immediately stopped and the corresponding pipe section is scrapped, where K3 is the third slope and ranges from 2 to 10.

[0033] Due to the adoption of the above technical solution, the technical advancements achieved by the present invention are:

[0034] 1. The present invention introduces compressed air into the interior of the pipe. The airflow enters the exhaust pipe from the exhaust pipe inlet and is then discharged from the exhaust pipe outlet until it blows onto the inner wall of the thermoplastic pipe. Since the exhaust pipe does not pass through the axis of the rotating air hood, the reaction force of the gas during the discharge process will generate torque on the rotating air hood, thereby causing the rotating air hood to start rotating. The discharged gas can continuously cool the inner wall of the pipe 360 ​​degrees during the rotation of the rotating air hood, that is, compressed air is used as the power to rotate the device, and compressed air is used as the medium to cool the inner wall of the pipe.

[0035] 2. The present invention ensures the sealing of the cooling device by employing seals, sealing rings, and circlips. A seal is located between the air intake seat and the rotating air hood. The seal is screwed to the air intake seat and adheres tightly to the inner cavity of the rotating air hood to prevent gas leakage. A circlip is also used to prevent axial displacement between the air intake seat and the rotating air hood, which could cause them to become detached. The sealing end cap is screwed to the rotating air hood and can rotate with it. A sealing ring is located between the sealing end cap and the air intake seat to prevent gas leakage.

[0036] 3. The present invention continuously measures the temperature of point A of the starting pipe section of the thermoplastic pipe after extrusion molding within a preset time. When the pipe section moves to the spin cooling device, the centralized control unit adjusts the opening of the electronically controlled proportional valve according to the corresponding strategy, and then controls the installation speed of the spin cooling device, thereby achieving the goal of stably cooling the inner wall temperature of the thermoplastic pipe to the desired temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1is a cross-sectional view of a gas powered spin cooling system for thermoplastic pipes according to the present invention;

[0038] Figure 2 is a front cross-sectional view of the gas-powered spin cooling device of the present invention;

[0039] Figure 3 This is a partial enlarged view of the gas-powered spin cooling device of the present invention;

[0040] Figure 4 is a side view of the gas powered spin cooling device of the present invention;

[0041] Among them, 1. Pull rod, 2. Air intake seat, 3. Rotating air cover, 4. Sealing end cover, 5. Air intake, 6. Elastic retaining ring, 7. Seal, 8. Sealing ring, 9. Exhaust pipe, 10. Thermoplastic pipe, 11. Centralized control unit, 12. Electric proportional valve, 13. Air intake pipe, 14. Extrusion die, 15. Extrusion core die, 16. Infrared temperature sensor, 17. Vacuum sizing box, 18. Wireless receiving transmitter, 19. Air source inlet, 20. Cooling water spray. DETAILED DESCRIPTION

[0042] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0043] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0044] Furthermore, the terms "first," "second," etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified with "first," "second," etc. may explicitly or implicitly include at least one such feature. In the description of the present invention, "several" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0045] like Figure 1 、 2 As shown, a gas-powered spin cooling system for thermoplastic pipes includes an extrusion molding device, a vacuum sizing box 17 arranged outside the extruded thermoplastic pipe, a spin cooling device arranged inside the extruded thermoplastic pipe, and an adaptive adjustment device for controlling the rotation speed of the spin cooling device;

[0046] The extrusion molding device includes an extrusion die 14 arranged outside the unextruded thermoplastic pipe and an extrusion core die 15 arranged outside the unextruded thermoplastic pipe;

[0047] The vacuum sizing box 17 is cylindrical, and a plurality of cooling water sprays 20 are provided on the inner wall;

[0048] like Figure 3 As shown, the spin cooling device includes a tie rod 1 arranged in a thermoplastic tube 10, a device body sleeved on the tie rod 1, and an air inlet pipe 13 for introducing airflow into the device body; the device body includes an air inlet seat 2, a rotating air cover 3 and a sealing end cover 4, and the air inlet seat 2, the rotating air cover 3 and the sealing end cover 4 are interconnected to form a closed circular column; the tie rod 1 is arranged at the center of the outlet of the extrusion molding device;

[0049] The air intake seat 2 includes an annular end surface, a connecting pipe provided on the inner circle of the end surface, and an outer edge provided on the outer circle of the end surface; an air intake inlet 5 is provided on the end surface of the air intake seat 2; the air intake inlet 5 is connected to the air intake pipe 13; the connecting pipe is fixedly connected to the pull rod 1; the upper surface of the outer edge is sequentially provided with a groove and a protrusion, and an elastic retaining ring 6 is provided on the groove;

[0050] like Figure 4 As shown, the rotating air hood 3 includes a cylindrical body, a first inner edge arranged at the front end of the cylindrical body and a second inner edge arranged at the rear end of the cylindrical body; an exhaust pipe 9 is arranged inside the cylindrical body; the first inner edge is clamped between the elastic retaining ring 6 and the protrusion; the inner diameter of the first inner edge is larger than the outer diameter of the outer edge, and the rotating air hood 3 can rotate relative to the air inlet seat 2; an exhaust pipe 9 is arranged inside the cylindrical body, and the inlet of the exhaust pipe 9 is arranged on the circular horizontal diameter of the cross section of the cylindrical body, and the distance from the center of the circle is greater than 3 / 4 of the radius, and the outlet of the exhaust pipe 9 is arranged on the cylindrical body; a sealing member 7 is also arranged in the rotating air hood 3, and the sealing member 7 is a conical elastic shell-shaped member; one end of the sealing member 7 is fixed to the air inlet seat 2 by a screw, and the other end is against the first inner edge of the rotating air hood 3, and is tightly attached to the inner cavity of the rotating air hood 3 to prevent gas leakage;

[0051] The sealing end cover 4 is fixed to the second inner edge of the rotating air cover 3 by screws; a sealing ring 8 is provided between the end of the sealing end cover 4 and the connecting pipe;

[0052] The adaptive adjustment device includes an electrically controlled proportional valve 12 connected to the starting end of the intake pipe 13, a centralized control unit 11 for controlling the opening of the electrically controlled proportional valve 12, and an infrared temperature sensor 16 arranged at the starting end of the pull rod 1; the data transmission mode of the infrared temperature sensor 16 is wireless transmission; the centralized control unit 11 is externally connected to a wireless receiving transmitter 18; the electrically controlled proportional valve 12 is provided with an air source inlet 19, which is externally connected to an air source.

[0053] A method for gas powered spin cooling of thermoplastic pipes comprises the following steps:

[0054] S1. The thermoplastic pipe 10 passes through the extrusion molding device and enters the vacuum sizing box 17 after extrusion. The vacuum sizing box 17 uses negative pressure to absorb the pipe to the inner wall of the sizing sleeve and move it from the L end to the R end. At the same time, the cooling water spray 20 cools the outer wall of the pipe.

[0055] S2, the infrared temperature sensor 16 collects the temperature of the starting pipe section A of the thermoplastic pipe 10 after extrusion, measures the inner wall temperature in real time and transmits it to the centralized control unit 11;

[0056] S3, the centralized control unit 11 controls the flow rate of the airflow in the air intake pipe 13 by adjusting the opening of the electronically controlled proportional valve 12, and then controls the opening of the electronically controlled proportional valve 12 when the test point moves to the rotary cooling device, so that the spin cooling device outputs a corresponding rotation speed to achieve different cooling effects; the airflow is injected into the inner cavity of the cooling device from the inlet of the air intake seat 2. After the inner cavity of the rotary cooling device is filled with gas, the airflow enters the exhaust pipe 9 from the inlet of the exhaust pipe 9, and then is discharged from the outlet of the exhaust pipe 9 until it is blown onto the inner wall of the thermoplastic pipe 10. During the rotation of the rotary air hood 3, the inner wall of the pipe is continuously cooled 360 degrees. M is the rotation direction of the rotary air hood 3;

[0057] In S3, the centralized control unit 11 controls the flow rate of the airflow in the intake pipe 13 by adjusting the opening of the electronically controlled proportional valve 12, which specifically includes the following steps:

[0058] S31 When the temperature change slope K collected by the centralized control unit 11 within the preset time period is in [-K1, K1] and is the same in sign, the centralized control unit takes the average temperature T within the preset time period because the change trend is single and the change amplitude is small. a , and calculate the opening D of the electronically controlled proportional valve:

[0059] D=A×(T a -T e ）

[0060] Among them, A is the proportional coefficient, T eis the desired temperature, K1 is the first slope, and the range is 0.1 to 0.5.

[0061] S32: When the temperature change slope K collected by the centralized control unit 11 within the preset time period is in [-K1, K1] and is positive or negative, or the minimum value of K is in [-K2, -K1), or the maximum value of K is in (K1, K2), the opening D of the electronically controlled proportional valve is calculated by the PID control method:

[0062]

[0063] Where Kp is the proportional gain, Ki is the integral gain, Kd is the differential gain, T is the real-time temperature, t is the preset time, and K2 is the second slope, ranging from 0.8 to 1;

[0064] S33: When the minimum value of the temperature change slope K within the preset time period collected by the centralized control unit 11 is [-K3, K2) or the maximum value of K is (K2, K3), the thermoplastic pipe production is immediately stopped and the corresponding pipe section is scrapped, where K3 is the third slope, ranging from 2 to 10.

[0065] Working principle:

[0066] The cooling device is secured to the tie rod 1 via the air intake seat 2. The contact area between the air intake seat 2 and the rotating air hood 3 utilizes a clearance fit, allowing them to rotate relative to each other. A seal 7 is located between the air intake seat 2 and the rotating air hood 3. This seal 7 is screwed to the air intake seat 2 and forms a tight fit within the interior of the rotating air hood 3, preventing gas leakage. The seal 7 is a conical shell that deforms to ensure sealing performance. As the air supply increases, the pressure within the rotating air hood gradually increases, pressing the seal 7 against the rotating air hood 3. The greater the pressure, the greater the contact pressure between the seal 7 and the rotating air hood 3, effectively ensuring sealing performance. Furthermore, the conical shell structure of the seal 7 relies on structural deformation rather than elastic deformation to ensure sealing. This effectively reduces frictional resistance between the seal 7 and the rotating air hood 3 while ensuring a tight seal. This ensures efficient operation of the rotating air hood 3. A circlip 6 is used to prevent axial displacement between the air intake seat 2 and the rotating air hood 3, which could cause disengagement. The sealing end cap 4 is screwed to the rotating air hood 3 and rotates with it. A sealing ring 8 is placed between the sealing end cap 4 and the air inlet seat 2 to prevent gas leakage. The rotating air hood 3 has an exhaust pipe 9, which does not pass through the axis of the rotating air hood 3 and is located at a distance from the axis.

[0067] By adjusting the gas input pressure at the inlet 5, for example, from 1 bar to 10 bar, according to Bernoulli's theorem and the law of conservation of mass, the outlet pressure will increase accordingly when the inlet and outlet areas remain relatively unchanged. Bernoulli's theorem:

[0068]

[0069] The product of the outlet pressure and the outlet area is the aforementioned reaction force, thereby increasing the rotational speed of the rotating air hood 3, that is, the amount of air sucked onto the inner wall of the tube 10 in the same period of time increases. When the moving speed of the thermoplastic tube 10 is constant, the cooling air volume increases.

[0070] Since the exhaust pipe 9 does not pass through the axis of the rotating air hood 3, the reaction force of the gas during the exhaust process will generate torque on the rotating air hood 3, thereby causing the rotating air hood 3 to start rotating; in this way, the exhausted gas can continuously cool the inner wall of the pipe 360 ​​degrees during the rotation of the rotating air hood 3.

[0071] By continuously measuring the temperature of point A of the starting section of the thermoplastic pipe 10 after extrusion within a preset time, when the pipe section moves to the spin cooling device, the centralized control unit 11 adjusts the opening of the electronically controlled proportional valve 12 according to the corresponding strategy, thereby controlling the installation speed of the spin cooling device, thereby achieving the goal of stably cooling the inner wall temperature of the thermoplastic pipe 10 to the desired temperature. Point B is the position of the thermoplastic pipe that has cooled to the desired temperature.

[0072] In summary, the present invention introduces compressed air into the interior of the pipe, thereby utilizing the compressed air as a driving force to rotate the device and using the compressed air as a medium to cool the inner wall of the pipe.

Claims

1. A gas powered spin cooling system for thermoplastic pipes, characterized by: It comprises an extrusion molding device, a vacuum sizing box (17) arranged outside the extruded thermoplastic pipe (10), a spin cooling device arranged inside the extruded thermoplastic pipe (10), and an adaptive adjustment device for controlling the rotation speed of the spin cooling device; The spin cooling device comprises a pull rod (1) arranged in a thermoplastic tube (10), a device body sleeved on the pull rod (1), and an air intake pipe (13) for introducing air flow into the device body; the device body comprises an air intake seat (2) fixedly connected to the pull rod (1), a rotating air cover (3) and a sealing end cover (4) that rotate relative to the air intake seat (2); the air intake seat (2), the rotating air cover (3) and the sealing end cover (4) are connected to each other to form a closed circular column; the air intake seat (2) is rotatably connected to the rotating air cover (3); An air inlet (5) is provided on the air inlet seat (2), and an exhaust pipe (9) is provided in the rotating air cover (3); the exhaust pipe (9) is provided in a non-axial position in the rotating air cover (3); The adaptive adjustment device comprises an electrically controlled proportional valve (12) connected to the starting end of the intake pipe (13), a centralized control unit (11) for controlling the opening of the electrically controlled proportional valve (12), and an infrared temperature sensor (16) provided at the starting end of the pull rod (1).

2. The gas powered spin cooling system for thermoplastic pipes according to claim 1, characterized in that: The air intake seat (2) comprises an annular end face, a connecting pipe arranged on the inner circle of the end face, and an outer edge arranged on the outer circle of the end face; an air intake inlet (5) is arranged on the end face of the air intake seat (2); the air intake inlet (5) is connected to the air intake pipeline (13); the connecting pipe is fixedly connected to the pull rod (1); a groove and a protrusion are arranged in sequence on the upper surface of the outer edge, and an elastic retaining ring (6) is arranged on the groove.

3. The gas powered spin cooling system for thermoplastic pipes according to claim 2, characterized in that: The rotating air hood (3) comprises a cylindrical body, a first inner edge arranged at the front end of the cylindrical body, and a second inner edge arranged at the rear end of the cylindrical body; an exhaust pipe (9) is arranged inside the cylindrical body; the first inner edge is clamped between the elastic retaining ring (6) and the protrusion; the inner diameter of the first inner edge is larger than the outer diameter of the outer edge, and the rotating air hood (3) can rotate relative to the air inlet seat (2); a sealing member (7) is arranged inside the rotating air hood (3), and the sealing member (7) is a conical elastic shell-shaped member; one end of the sealing member (7) is fixed to the air inlet seat (2) by a screw, and the other end abuts against the first inner edge of the rotating air hood (3).

4. The gas powered spin cooling system for thermoplastic pipes according to claim 3, characterized in that: The sealing end cover (4) is fixed to the second inner edge of the rotating air cover (3) by screws; a sealing ring (8) is provided between the end of the sealing end cover (4) and the connecting pipe.

5. The gas powered spin cooling system for thermoplastic pipes according to claim 3, characterized in that: The inlet of the exhaust pipe (9) is arranged on the circular diameter of the cross section of the cylindrical body, with a distance from the center of the circle greater than 3 / 4 of the radius, and the outlet of the exhaust pipe (9) is arranged on the cylindrical body.

6. The gas powered spin cooling system for thermoplastic pipes according to claim 1, characterized in that: The extrusion molding device comprises an extrusion die (14) arranged outside the unextruded thermoplastic pipe and an extrusion core die (15) arranged outside the unextruded thermoplastic pipe.

7. The gas powered spin cooling system for thermoplastic pipes according to claim 1, characterized in that: The vacuum sizing box (17) is cylindrical, and a plurality of cooling water sprays (20) are provided on the inner wall.

8. The gas powered spin cooling system for thermoplastic pipes according to claim 1, characterized in that: The infrared temperature sensor (16) transmits data in a wireless transmission mode; the centralized control unit (11) is externally connected to a wireless receiving transmitter (18); and the electrically controlled proportional valve (12) is provided with an air source inlet (19) for connecting to an external air source.

9. A method for gas-powered spin cooling of thermoplastic pipes, characterized in that: The gas powered spin cooling system for thermoplastic pipes according to any one of claims 1 to 8 comprises the following steps: S1. The thermoplastic pipe (10) passes through an extrusion molding device and enters a vacuum sizing box (17) after extrusion. The vacuum sizing box (17) uses negative pressure to adsorb the pipe onto the inner wall of the sizing sleeve and moves forward. At the same time, a cooling water spray (20) cools the outer wall of the pipe. S2, an infrared temperature sensor (16) collects data from the starting section of the extruded thermoplastic pipe (10), measures the inner wall temperature in real time, and transmits the temperature to the centralized control unit (11); S3, the centralized control unit (11) controls the flow rate of the air flow in the air intake pipe (13) by adjusting the opening of the electronically controlled proportional valve (12), and then controls the opening of the electronically controlled proportional valve (12) when the test point moves to the rotary cooling device, so that the spin cooling device outputs a corresponding rotation speed.

10. The gas-powered spin cooling method for thermoplastic pipes according to claim 9, characterized in that: The centralized control unit (11) in S3 controls the flow rate of the air in the air intake pipe (13) by adjusting the opening of the electronically controlled proportional valve (12), which specifically includes the following steps: S31 When the temperature change slope K collected by the centralized control unit (11) within the preset time period is in [-K1, K1] and is the same in sign, the centralized control unit takes the average temperature T within the preset time period. a , and calculate the opening D of the electronically controlled proportional valve: D=A×(T a -T e ） Among them, A is the proportional coefficient, T e is the desired temperature, K1 is the first slope, ranging from 0.1 to 0.5; S32 When the temperature change slope K collected by the centralized control unit (11) within the preset time period is in [-K1, K1] and is positive or negative, or the minimum value of K is in [-K2, -K1) or the maximum value of K is in (K1, K2), the opening D of the electronically controlled proportional valve is calculated by the PID control method: ； Where Kp is the proportional gain, Ki is the integral gain, Kd is the differential gain, T is the real-time temperature, t is the preset time, and K2 is the second slope, ranging from 0.8 to 1; S33 When the minimum value of the temperature change slope K within the preset time period collected by the centralized control unit (11) is in [-K3, K2) or the maximum value of K is in (K2, K3), the production of the thermoplastic pipe is immediately stopped and the corresponding pipe section is discarded, wherein K3 is the third slope, ranging from 2 to 10.

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