System for manufacturing peroxide crosslinked polyethylene pipe

Abstract

The present invention relates to the technical field of peroxide crosslinked polyethylene pipe manufacturing, and discloses a peroxide crosslinked polyethylene pipe manufacturing system, which comprises: an extruder, which is used for extruding a molded pipe; the cross-linking furnace is arranged on one side of the extruder, the cross-linking furnace is provided with a cross-linking cavity with a front opening and a rear opening, and the cross-linking cavity is used for allowing the pipe to penetrate through and carrying out a cross-linking reaction; the first microwave generator is arranged between the extruder and the cross-linking furnace, the first microwave generator is provided with a first activation cavity allowing the pipe to penetrate through, and microwaves generated by the first microwave generator act on the pipe through the first activation cavity. By means of the structure, the cross-linking reaction can be more uniform, and the quality of the pipe is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of manufacturing peroxide cross-linked polyethylene pipes, and particularly to a system for manufacturing peroxide cross-linked polyethylene pipes. Background Art

[0002] During the cross-linking reaction process of peroxide cross-linked polyethylene pipes, the pipe wall structure has a certain thickness, resulting in limited infrared penetration performance and insufficient cross-linking reaction in the inner layer of the pipe. This situation causes an obvious difference in cross-linking degree between the inner and outer layers inside the pipe, which has a significant adverse impact on the comprehensive performance of the pipe and the stability of product quality. Summary of the Invention

[0003] The object of the present invention is to provide a system for manufacturing peroxide cross-linked polyethylene pipes, which can make the cross-linking reaction more uniform and improve the quality of the pipes.

[0004] To achieve the above object, the present invention provides a system for manufacturing peroxide cross-linked polyethylene pipes, including: An extruder for extruding and forming pipes; A cross-linking furnace having a cross-linking cavity with front and rear openings, and the cross-linking cavity is used for the pipe to pass through and undergo a cross-linking reaction; A first microwave generator disposed between the extruder and the inlet of the cross-linking furnace. The first microwave generator has a first activation cavity for the pipe to pass through, and the microwave generated by the first microwave generator acts on the pipe through the first activation cavity to activate the pipe.

[0005] In some embodiments of the present invention, the system for manufacturing peroxide cross-linked polyethylene pipes further includes: A second microwave generator disposed on the outlet side of the cross-linking furnace. The second microwave generator has a second activation cavity for the pipe to pass through, and the microwave generated by the second microwave generator acts on the pipe through the second activation cavity to cause the unreacted groups or cross-linking points inside the pipe to continue to react. In some embodiments of the present invention: The structure of the first microwave generator is the same as that of the second microwave generator.

[0006] In some embodiments of the present invention: The microwave frequency range generated by the first microwave generator is 2.4 GHz - 2.5 GHz, and the power range is 0.5 kW - 2 kW.

[0007] In some embodiments of the present invention: The first microwave generator includes a cabinet, a resonance mechanism, and a magnetron. The resonance mechanism and the magnetron are disposed inside the cabinet. The resonance mechanism has a housing forming a resonance cavity, and the housing further forms the first activation cavity in the shape of a through hole. The magnetron is disposed around the cavity wall of the first activation cavity.

[0008] In some embodiments of the present invention: In some embodiments of the present invention: A reflecting surface is provided on the cavity wall of the first activation cavity, and the reflecting surface is at least a part of the cavity wall of the first activation cavity.

[0009] In some embodiments of the present invention: The first microwave generator further includes a cooling pipe. A through hole is provided on the resonance mechanism. At least a part of the cooling pipe extends into the through hole and communicates with the first activation cavity. The cooling medium of the cooling pipe is a protective gas.

[0010] In some embodiments of the present invention: The crosslinking furnace has an infrared emitter. The infrared rays emitted by the infrared emitter enter the crosslinking cavity. The crosslinking cavity includes a first cavity, a second cavity, and a third cavity sequentially arranged along the moving direction of the pipe. The wavelength of the infrared rays emitted by the infrared emitter entering the first cavity is within a first frequency band, the wavelength of the infrared rays emitted by the infrared emitter entering the second cavity is within a second frequency band, and the wavelength of the infrared rays emitted by the infrared emitter entering the third cavity is within a third frequency band. The first frequency band is greater than the second frequency band, the second frequency band is greater than the third frequency band, and the first frequency band, the second frequency band, and the third frequency band do not overlap with each other.

[0011] In some embodiments of the present invention: The extruder has a first nozzle for introducing a protective gas into the inner hole of the pipe; The crosslinking furnace has a second nozzle for introducing a protective gas into the crosslinking cavity, and the gas outlet direction of the second nozzle is arranged along the radial direction of the pipe.

[0012] In some embodiments of the present invention, the system for manufacturing a peroxide crosslinked polyethylene pipe further includes: A cooling water tank, an infrared spectrometer, and a tractor. The crosslinking furnace, the cooling water tank, the infrared spectrometer, and the tractor of the system for manufacturing a peroxide crosslinked polyethylene pipe are sequentially arranged along the moving direction of the pipe extruded by the extruder.

[0013] The present invention provides a system for manufacturing a peroxide crosslinked polyethylene pipe. Compared with the prior art, its beneficial effects are as follows: The system for manufacturing peroxide cross-linked polyethylene pipes of the present invention includes an extruder, a cross-linking furnace, and a first microwave generator. Before the pipes from the extruder enter the cross-linking furnace for cross-linking reaction, they are first activated by the microwave generated by the first microwave generator through non-thermal effect to destroy the polyethylene crystalline region, promote the uniform dispersion of peroxide inside the pipes, activate the pipes before the cross-linking reaction, and then the pipes undergo cross-linking reaction. This can enable more sufficient cross-linking reaction to occur in the inner and outer layers of the pipes, make the cross-linking reaction more uniform, and improve the quality of the pipes. At the same time, it can also shorten the time of the cross-linking reaction and improve the efficiency of the cross-linking reaction. Brief Description of the Drawings

[0014] Figure 1 It is a schematic diagram of the system for manufacturing peroxide cross-linked polyethylene pipes according to an embodiment of the present invention.

[0015] Figure 2 It is a schematic diagram of the first microwave generator according to an embodiment of the present invention.

[0016] Figure 3 It is an internal schematic diagram of the first microwave generator according to an embodiment of the present invention.

[0017] Figure 4 It is a schematic diagram of the structure of the resonance mechanism and the cooling pipe according to an embodiment of the present invention.

[0018] Figure 5 It is a schematic diagram of the structure of the cooling pipe according to an embodiment of the present invention.

[0019] Figure 6 It is a schematic diagram of the cross-linking furnace according to an embodiment of the present invention.

[0020] Figure 7 It is a sectional view of the first furnace body according to an embodiment of the present invention.

[0021] In the figure, 100, cross-linking furnace; 200, extruder; 300, first microwave generator; 400, second microwave generator; 500, cooling water tank; 600, infrared spectrometer; 700, tractor; 800, pipe cutting machine; 120, first furnace body; 130, second furnace body; 140, third furnace body; 150, second nozzle; 310, first activation chamber; 320, cabinet; 330, resonance mechanism; 340, magnetron; 350, housing; 360, cooling pipe; 311, reflecting surface. Detailed Embodiments

[0022] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0023] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is 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 should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0024] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0025] In addition, in the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0026] For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0027] A system for manufacturing a peroxide cross-linked polyethylene pipe according to a preferred embodiment of an embodiment of the present invention includes: an extruder 200, a cross-linking furnace 100, and a first microwave generator 300.

[0028] The extruder 200 is used for extruding and forming a pipe.

[0029] The cross-linking furnace 100 is arranged on one side of the extruder 200. The cross-linking furnace 100 has a cross-linking cavity with front and rear openings. The cross-linking cavity is used for the pipe to pass through and undergo a cross-linking reaction.

[0030] The first microwave generator 300 is arranged between the extruder 200 and the inlet of the cross-linking furnace 100. The first microwave generator 300 has a first activation cavity 310 for the pipe to pass through. The microwave generated by the first microwave generator 300 acts on the pipe through the first activation cavity 310 to activate the pipe.

[0031] After the pipe is extruded by the extruder 200, it first enters the first activation chamber 310 of the first microwave generator 300. The microwave acts on the pipe to activate the pipe embryo containing peroxide by non-thermal effect, destroy the molecular chain arrangement of the polyethylene crystal region, make the molecular chain looser, make the molecular chain more active, enhance the activity of the molecular chain, promote the uniform dispersion of peroxide in the pipe, activate the pipe before the cross-linking reaction, and prepare for the subsequent cross-linking reaction. After that, the pipe enters the cross-linking furnace 100 for cross-linking reaction, which can make the inner layer of the pipe also undergo a relatively sufficient cross-linking reaction, make the cross-linking reaction of the inner and outer layers of the pipe more uniform, and improve the quality of the pipe. At the same time, it can also shorten the time of the cross-linking reaction, improve the efficiency of the cross-linking reaction, reduce the crystallinity of the pipe, and reduce the uneven cross-linking degree caused by the obstruction of the polyethylene crystal region.

[0032] In some embodiments, the system for manufacturing peroxide cross-linked polyethylene pipe further includes a second microwave generator 400, which is disposed on a side of the cross-linking furnace 100 away from the first microwave generator 300 and is also located on the exit side of the cross-linking furnace 100. The second microwave generator 400 has a second activation cavity for the pipe to pass through. The microwaves generated by the second microwave generator 400 act on the pipe through the second activation cavity, so that the groups or cross-linking points inside the pipe that have not been completely reacted continue to react.

[0033] After the tube has undergone the cross-linking reaction in the cross-linking furnace 100, it enters the second activation cavity of the second microwave generator 400. The microwave acts on the tube. The microwave can make the unreacted groups or cross-linking points inside the tube continue to react, making the cross-linking structure more uniform and complete, thereby improving the performance of the tube.

[0034] The microwave frequency range of the first microwave generator 300 is 2.4 GHz-2.5 GHz, and the power range is 0.5 kW-2 kW. Within this parameter range, microwaves accelerate the thermal motion of molecules inside the tube and promote the rearrangement and orientation of molecular chains; on the other hand, the local high temperature microenvironment induced by them helps to activate potential chemical reaction sites, thereby significantly improving the activation degree of the tube and having a good effect of activating the tube.

[0035] If the microwave frequency is lower than 2.4 GHz, the energy absorption rate of the pipe to the microwave will decrease, and the activation effect will be poor. If the microwave frequency is higher than 2.5 GHz, the penetration ability of the microwave to the pipe will decrease, and the microwave energy will be concentrated on the outer layer of the pipe, resulting in a large temperature difference between the inside and outside of the pipe, which will aggravate the uneven cross-linking.

[0036] If the microwave power is lower than 0.5 kW, the microwave energy is insufficient to break the polyethylene crystalline region, resulting in uneven dispersion of peroxides and uneven cross-linking reactions inside and outside the pipe. If the microwave power is higher than 2 kW, the local thermal effect of the pipe is significant, the temperature of the inner layer of the pipe rises suddenly, causing premature decomposition of peroxides and reducing the cross-linking efficiency.

[0037] In this embodiment, the structure of the first microwave generator 300 is the same as that of the second microwave generator 400. The following takes the first microwave generator 300 as an example to introduce the specific structure.

[0038] The first microwave generator 300 includes a cabinet 320, a resonance mechanism 330, and a magnetron 340. The resonance mechanism 330 and the magnetron 340 are arranged inside the cabinet 320. The resonance mechanism 330 has a housing 350 forming a resonance cavity. The housing 350 also forms a through-hole-shaped first activation cavity 310. The magnetron 340 is arranged around the cavity wall of the first activation cavity 310.

[0039] The magnetron 340 can generate microwaves. The resonance mechanism 330 screens and maintains the microwaves generated by the magnetron 340 at a specific frequency, so that the microwaves of the required frequency act on the pipe in the first activation cavity 310 to activate the pipe.

[0040] The magnetron 340 and the resonance mechanism 330 are prior arts and will not be elaborated here.

[0041] A reflecting surface 311 is provided on the cavity wall of the first activation cavity 310. The reflecting surface 311 surrounds the pipe passing through the first activation cavity 310. The reflecting surface 311 is at least a part of the cavity wall of the first activation cavity 310.

[0042] In this embodiment, the reflecting surface 311 is formed by the inner wall of the first activation cavity 310. At least a part of the microwaves are reflected by the reflecting surface 311 and then act on the pipe. The reflecting surface 311 is a silver-plated layer on stainless steel, which can allow the microwaves to penetrate the pipe more evenly.

[0043] The first microwave generator 300 further includes a cooling pipe 360. The cooling pipe 360 is connected to the first activation cavity 310. The cooling medium of the cooling pipe 360 is a protective gas.

[0044] In this embodiment, the protective gas is carbon dioxide gas. In other embodiments, other gases such as nitrogen can also be used as the protective gas.

[0045] The resonance mechanism 330 is provided with a through-hole. The cooling pipe 360 is inserted into the through-hole and extends into the first activation cavity 310 to introduce the protective gas into the first activation cavity 310. The protective gas can protect the surface of the pipe and cool the resonance mechanism 330.

[0046] The first microwave generator 300 further includes a heat insulation layer disposed outside the resonance mechanism 330. The heat insulation layer can be arranged in a plate shape to enclose the resonance mechanism 330 inside.

[0047] The cabinet 320 is provided with a double-layer aluminum-magnesium alloy shielding net to prevent electromagnetic leakage.

[0048] In some embodiments, the crosslinking furnace 100 has an infrared emitter. The infrared rays emitted by the infrared emitter enter the crosslinking cavity. The crosslinking cavity includes a first cavity, a second cavity, and a third cavity arranged in sequence along the movement direction of the pipe. The infrared rays emitted by the infrared emitter entering the first cavity are within the first frequency band. The wavelength of the infrared rays emitted by the infrared emitter entering the second cavity is within the second frequency band. The wavelength of the infrared rays emitted by the infrared emitter entering the third cavity is within the third frequency band. The first frequency band is greater than the second frequency band, the second frequency band is greater than the third frequency band, and the first frequency band, the second frequency band, and the third frequency band do not overlap with each other. The first frequency band can be set as long wave, the second frequency band can be set as medium wave, and the third frequency band can be set as short wave.

[0049] The wavelength of the infrared rays emitted by the infrared emitter entering the first cavity is greater than the wavelength of the infrared rays emitted by the infrared emitter entering the second cavity, and the wavelength of the infrared rays emitted by the infrared emitter entering the second cavity is greater than the wavelength of the infrared rays emitted by the infrared emitter entering the third cavity.

[0050] The infrared emitter can be infrared lamps respectively arranged in the first cavity, the second cavity, and the third cavity.

[0051] The crosslinking furnace 100 is provided with three furnace bodies. The first cavity is arranged in the first furnace body 120, the second cavity is arranged in the second furnace body 130, and the third cavity is arranged in the third furnace body 140.

[0052] After the pipe is extruded by the extruder 200, it first enters the first cavity and is heated by the infrared rays emitted by the infrared emitter in the first cavity, then enters the second cavity and is heated by the infrared rays emitted by the infrared emitter in the second cavity, and finally enters the third cavity and is heated by the infrared rays emitted by the emitter in the third cavity. The infrared rays in the first cavity penetrate the surface layer of the pipe for heating. The infrared rays in the second cavity enhance the heat absorption in the middle layer of the pipe. The infrared rays in the third cavity strengthen the heat absorption in the inner layer of the pipe, further reducing the temperature difference of the pipe, promoting the crosslinking reaction, and realizing synchronous heating of the inner and outer layers of the pipe by infrared rays with different wavelengths, so that the crosslinking reaction of the pipe is more uniform, and further improving the quality of the pipe. Since the pipe has been microwave-activated before entering the crosslinking cavity, the microwave preferentially activates the inside, so that the peroxides and molecular chains inside the pipe are first activated, preparing for the crosslinking reaction; the infrared radiation strengthens the crosslinking of the outer layer of the pipe and heats the pipe from the outside, enabling the crosslinking reaction on the surface layer to proceed fully. This synergistic effect improves the decomposition efficiency of peroxides, shortens the crosslinking reaction time, and at the same time reduces the crystallinity of the pipe, avoiding the problem of uneven crosslinking degree caused by the hindrance of the crystalline region.

[0053] Specifically, the first frequency band range is 3 - 5 μm, belonging to the long wave; the second frequency band range is 1.5 - 3 μm, belonging to the medium wave; the third frequency band range is 0.8 - 1.2 μm, belonging to the short wave.

[0054] Through such wavelength ranges, the purpose is to heat the surface layer with infrared rays in the first cavity, heat the middle layer with infrared rays in the second cavity, and heat the inner layer with infrared rays in the third cavity.

[0055] The outer layer refers to the part of the pipe near the outer wall, the inner layer refers to the part of the pipe near the inner wall, and the middle layer refers to the part between the outer layer and the inner layer.

[0056] The extruder 200 has a first nozzle for introducing a protective gas into the inner hole of the pipe.

[0057] The crosslinking furnace 100 has a second nozzle 150 for introducing a protective gas into the crosslinking cavity, and the gas outlet direction of the second nozzle 150 is set along the radial direction of the pipe.

[0058] The extruder 200 is used to extrude the pipe. The first nozzle is arranged along the axial direction of the pipe, so that the gas can flow along the length direction of the pipe, forming a low-oxygen environment on the inner surface of the pipe, avoiding the oxidation of peroxides by oxygen, and ensuring the smooth progress of the crosslinking reaction.

[0059] The second nozzle 150 introduces a protective gas, and the gas flow rate ≥ 5 m / s. The protective gas entering from the second nozzle 150 can form a surrounding air flow on the surface of the pipe. The surrounding air flow continuously flushes the surface of the pipe, taking away the possible existing oxygen, preventing the peroxides from being insufficiently decomposed or generating other side reactions due to the interference of oxygen during the crosslinking process; on the other hand, it also helps to make the temperature on the surface of the pipe uniform, making the crosslinking reaction more uniform.

[0060] The system for manufacturing a peroxide crosslinked polyethylene pipe in some embodiments further includes: a cooling water tank 500, an infrared spectrometer 600, and a tractor 700. The crosslinking furnace 100, the cooling water tank 500, the infrared spectrometer 600, and the tractor 700 of the system for manufacturing a peroxide crosslinked polyethylene pipe are arranged in sequence along the movement direction of the pipe extruded by the extruder 200.

[0061] The cooling water tank 500 is used to cool and shape the pipe.

[0062] The infrared spectrometer 600 is used to detect the crosslinking degree of the pipe. The spectral data detected by the infrared spectrometer 600 is transmitted to the controller, and the controller analyzes and processes the data to calculate the current crosslinking degree. Then, based on the preset crosslinking degree standard and the actual crosslinking degree data, the controller dynamically adjusts process parameters such as infrared power, traction speed, and carbon dioxide flow rate. For example, when the crosslinking degree is lower than the standard value, the infrared power is increased, the traction speed is decreased, or the carbon dioxide flow rate is adjusted to promote the crosslinking reaction; when the crosslinking degree is higher than the standard value, the opposite adjustment measures are taken to achieve closed-loop control of the process parameters and ensure that the crosslinking degree of the pipe is always within the ideal range.

[0063] The tractor 700 is used to provide traction force for the pipe and guide the pipe to move along its own axial direction.

[0064] A pipe cutting machine 800 can also be set on the side of the tractor 700 away from the infrared spectrometer 600.

[0065] In the process of producing 4-inch crosslinked polyethylene pipes according to the ASTM F876 standard in this embodiment, compared with the traditional vertical crosslinking furnace, the crosslinking uniformity is improved by more than 50%, and the utilization rate of peroxide is increased by 35%.

[0066] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and replacements can still be made, and these improvements and replacements should also be regarded as the protection scope of the present invention.

Claims

1. A system for manufacturing peroxide cross-linked polyethylene pipes, characterized in that, Comprising: An extruder for extruding and molding pipes; A cross-linking furnace having a cross-linking cavity with front and rear openings, the cross-linking cavity being for the pipe to pass through and undergo a cross-linking reaction; A first microwave generator disposed between the extruder and the inlet of the cross-linking furnace, the first microwave generator having a first activation cavity for the pipe to pass through, and the microwave generated by the first microwave generator acts on the pipe through the first activation cavity to activate the pipe.

2. The system for manufacturing a peroxide crosslinked polyethylene pipe according to claim 1, wherein Further comprising: A second microwave generator disposed on the outlet side of the cross-linking furnace, the second microwave generator having a second activation cavity for the pipe to pass through, and the microwave generated by the second microwave generator acts on the pipe through the second activation cavity to cause the unreacted groups or cross-linking points inside the pipe to continue to react.

3. The system for manufacturing a peroxide cross-linked polyethylene pipe according to claim 2, wherein: The structure of the first microwave generator is the same as that of the second microwave generator.

4. The system for manufacturing a peroxide cross-linked polyethylene pipe according to claim 1, wherein: The microwave frequency range generated by the first microwave generator is 2.4 GHz - 2.5 GHz, and the power range is 0.5 kW - 2 kW.

5. The system for manufacturing a peroxide cross-linked polyethylene pipe according to claim 1, wherein: The first microwave generator includes a cabinet, a resonance mechanism, and a magnetron. The resonance mechanism and the magnetron are disposed inside the cabinet. The resonance mechanism has a housing forming a resonance cavity, and the housing also forms the first activation cavity in the shape of a through hole. The magnetron is disposed around the cavity wall of the first activation cavity.

6. The system for manufacturing a peroxide cross-linked polyethylene pipe according to claim 5, wherein: A reflecting surface is provided on the cavity wall of the first activation cavity, and the reflecting surface is at least a part of the cavity wall of the first activation cavity.

7. The system for manufacturing a peroxide cross-linked polyethylene pipe according to claim 5, wherein: The first microwave generator further includes a cooling pipe. The resonance mechanism is provided with a through hole, and at least a part of the cooling pipe extends into the through hole and communicates with the first activation cavity. The cooling medium of the cooling pipe is a protective gas.

8. The system for manufacturing a peroxide cross-linked polyethylene pipe according to claim 1, wherein: The cross-linking furnace has an infrared emitter. The infrared rays emitted by the infrared emitter enter the cross-linking cavity. The cross-linking cavity includes a first cavity, a second cavity, and a third cavity sequentially arranged along the movement direction of the pipe. The wavelength of the infrared rays emitted by the infrared emitter into the first cavity is within a first frequency band, the wavelength of the infrared rays emitted by the infrared emitter into the second cavity is within a second frequency band, and the wavelength of the infrared rays emitted by the infrared emitter into the third cavity is within a third frequency band. The first frequency band is greater than the second frequency band, the second frequency band is greater than the third frequency band, and the first frequency band, the second frequency band, and the third frequency band do not overlap with each other.

9. The system for manufacturing peroxide cross-linked polyethylene pipes according to claim 8, characterized in that: The extruder has a first nozzle for introducing a protective gas into the inner hole of the pipe; The cross-linking furnace has a second nozzle for introducing a protective gas into the cross-linking cavity, and the gas outlet direction of the second nozzle is arranged along the radial direction of the pipe.

10. The system for manufacturing a peroxide crosslinked polyethylene pipe according to claim 9, characterized in that, It further includes: A cooling water tank, an infrared spectrometer and a tractor, and the cross-linking furnace, the cooling water tank, the infrared spectrometer and the tractor of the system for manufacturing peroxide cross-linked polyethylene pipes are arranged in sequence along the movement direction of the pipe extruded by the extruder.

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