Cooling device for large-size pe pipe production
By designing internal and external wall cooling components, synchronous cooling of the inner and outer walls of large-size PE pipes is achieved, solving the temperature difference problem between the inner and outer walls and improving the overall mechanical properties and service life of PE pipes.
Patent Information
- Application Number
- CN202522590574.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-05
- Publication Date
- 2026-11-03
- Estimated Expiration
- 2035-12-05
AI Technical Summary
In the production process of large-size PE pipes, the existing technology has a significant temperature difference between the inner and outer walls, which leads to asynchronous cooling of the inner and outer walls, resulting in residual stress and affecting the comprehensive mechanical properties and service life of the PE pipe.
The system employs internal and external wall cooling components. The external wall cooling component cools the external wall using coolant and airflow, while the internal wall cooling component cools the internal wall using airflow. This creates a cooling airflow that reduces the temperature difference between the internal and external walls, thereby minimizing the accumulation of residual stress.
It effectively reduces the temperature difference between the inner and outer walls of the tubular blank, reduces residual stress, improves the overall mechanical properties of PE pipe, and extends its service life.
Smart Images
Figure CN224928483U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of PE pipe production technology, and in particular to a cooling device for the production of large-size PE pipes. Background Technology
[0002] Polyethylene (PE) pipes are widely used in water supply, drainage, gas transmission, and agricultural irrigation due to their excellent corrosion resistance, flexibility, long service life, and convenient construction. Their production process mainly employs extrusion molding. First, PE raw materials and necessary additives are fed into an extruder. Through the rotation and heating of the screw, the raw materials are plasticized into a molten state. Then, the molten material is pushed through a die by the screw to form a tubular preform. Next, the tubular preform moves forward under the pull of a traction mechanism and enters a shaping and cooling equipment for cooling and solidification. Then, the completely cooled and solidified tubular preform is cut into PE pipes of predetermined length by a length-cutting device. Finally, the PE pipes are inspected, and qualified products are packaged and stored.
[0003] Currently, in the cooling and solidification process of tubular preforms, the industry commonly uses cooling from the outer surface of the preform. However, in the production of large-size PE pipes, the significant increase in wall thickness and heat capacity slows down heat transfer between the inner and outer walls. This unidirectional cooling method from the outer surface results in a situation where the outer wall temperature is low, but the inner wall temperature remains high, creating a significant temperature difference between the inner and outer walls. This causes the outer wall to cool and solidify before the inner wall. When the outer wall shrinks, it is constrained by the still-high-temperature inner wall; conversely, when the inner wall shrinks subsequently, it is restricted by the already solidified outer wall. This asynchronous shrinkage of the inner and outer walls of the preform accumulates a large amount of residual stress within it, leading to problems such as substandard roundness, dimensional instability, and even warping or serpentine bending. Ultimately, this results in a decrease in the overall mechanical properties of the PE pipe and a shortened service life. Utility Model Content
[0004] In view of this, it is necessary to provide a cooling device for the production of large-size PE pipes, which is used to cool the tubular preform to reduce the temperature difference between the inner and outer walls during the cooling process of the tubular preform, thereby reducing the accumulation of residual stress inside the tubular preform, thus improving the comprehensive mechanical properties of PE pipes and extending their service life.
[0005] This utility model provides a cooling device for the production of large-size PE pipes, including at least one outer wall cooling component and an inner wall cooling component. Each outer wall cooling component is disposed between an extruder and a fixed-length cutting device. The tubular preform produced by the extruder passes through the interior of each outer wall cooling component and reaches the fixed-length cutting device, so as to cool the outer wall of the tubular preform through each outer wall cooling component. The inner wall cooling component includes an air outlet component and an air suction component. The air outlet component is disposed on the discharge side of the fixed-length cutting device, and its air outlet end faces the inner wall of the tubular preform to blow air into the interior of the tubular preform. The air suction component is installed at the feed end of the extruder, and its air extraction end is connected to the feed end of the extruder to extract air from the interior of the tubular preform, thereby forming a cooling airflow flowing from the air outlet component to the air suction component inside the tubular preform.
[0006] Preferably, the air outlet assembly includes a fixed frame, at least one telescopic group, and a blowing group. The bottom of the fixed frame is located on the discharge side of the fixed-length cutting device and maintains a predetermined distance from the fixed-length cutting device. The fixed end of the first telescopic group is connected to the top of the fixed frame, and the fixed end of the subsequent telescopic group is connected to the telescopic end of the previous telescopic group. The fixed end of the blowing group is installed on the telescopic end of the last telescopic group, and the air outlet is directly facing the opening of the tubular blank to deliver air into the interior of the tubular blank.
[0007] Preferably, each telescopic assembly includes a first adjusting frame, a second adjusting frame, a scissor-type telescopic frame, and two telescopic drive components. The first adjusting frame is connected to the top of the fixed frame or the second adjusting frame of the adjacent telescopic assembly. The two ends of the scissor-type telescopic frame are respectively connected to the first adjusting frame and the second adjusting frame, so that the distance between the second adjusting frame and the first adjusting frame is adjustable. The fixed ends of the two telescopic drive components are respectively set at the two ends of the second adjusting frame, and the telescopic ends are connected to the scissor-type telescopic frame, which is used to drive the scissor-type telescopic frame to produce telescopic deformation through the telescopic extension and retraction of the telescopic drive components.
[0008] Preferably, each telescopic assembly further includes a flow guide, the two ends of which are connected to the first adjustment frame and the second adjustment frame respectively, and surround the scissor telescopic frame to guide airflow.
[0009] Preferably, the air blowing assembly includes two air blowers, which are symmetrically mounted on the second adjustment frame of the last telescopic assembly, and the air outlets of both air blowers face the inner wall of the tubular blank to deliver air into the interior of the tubular blank.
[0010] Preferably, the air outlet assembly further includes a cooling pipe, which is coiled around the top of the mounting frame and connected to an external refrigeration device to reduce the temperature of the air flowing through the cooling pipe.
[0011] Preferably, the suction assembly includes a mounting frame, a suction pipe, a suction chamber, fan blades, and a drive motor. The mounting frame is disposed at the feed end of the extruder, the suction chamber is disposed on the mounting frame, the fan blades are rotatably mounted in the suction chamber, the fixed end of the drive motor is mounted on the mounting frame, the drive end extends into the suction chamber and is drivenly connected to the fan blades, one end of the suction pipe is connected to the air inlet end of the suction chamber, and the other end is connected to the feed end of the extruder and aligned with the center of the tubular preform, so that when the drive motor drives the fan blades to rotate, the air inside the tubular preform, together with a small amount of ambient air sucked in from the feed port, is extracted and a stable negative pressure cooling airflow is formed inside the tubular preform.
[0012] Preferably, each outer wall cooling component includes a cooling box, two annular cooling pipes, and at least two axial cooling pipes. The cooling box is located between the extruder and the fixed-length cutting device, and has through holes at both ends for the tubular blank to pass through. The two annular cooling pipes are respectively located in the cooling box near both ends and are coaxially arranged with the through holes. Each axial cooling pipe is evenly distributed along the circumference of the annular cooling pipes, and each end is connected to the two annular cooling pipes, so that the annular cooling pipes and the axial cooling pipes together form a closed cooling circuit around the tubular blank. One of the annular cooling pipes is connected to an external liquid supply device to allow the coolant to circulate in the cooling circuit. Each axial cooling pipe has multiple nozzles evenly arranged on the side facing the tubular blank to uniformly spray the coolant onto the outer wall of the tubular blank for cooling.
[0013] Preferably, each outer wall cooling component further includes at least two support frames, each support frame is installed inside the cooling box and is symmetrically arranged on both sides of the tubular blank, each support frame is provided with at least one support roller at the top, and each support roller is rotatably installed on the top of the support frame to support the outer wall of the tubular blank.
[0014] The aforementioned cooling device for large-size PE pipe production includes at least one external wall cooling component and an internal wall cooling component. Each external wall cooling component is positioned between the extruder and the fixed-length cutting device. The tubular preform produced by the extruder passes through the interior of each external wall cooling component before reaching the fixed-length cutting device, where the external wall cooling components cool the outer wall of the preform. The internal wall cooling component includes an air outlet assembly and an air suction assembly. The air outlet assembly is located on the discharge side of the fixed-length cutting device, with its outlet facing the inner wall of the preform to blow air into its interior. The air suction assembly is installed at the feed end of the extruder, with its exhaust end facing the extruder. The feed end of the machine is connected to draw air from the inside of the tubular preform, thereby forming a cooling airflow from the air outlet component to the air suction component inside the tubular preform. In this way, the outer wall cooling component located between the extruder and the fixed-length cutting equipment cools the outer wall of the tubular preform, while the inner wall cooling component forms a cooling airflow from the air outlet component to the air suction component inside the tubular preform to cool the inner wall of the tubular preform. This reduces the temperature difference between the inner and outer walls of the tubular preform during the cooling process, reduces the accumulation of residual stress inside the tubular preform, thereby improving the overall mechanical properties of the PE pipe and extending its service life. Attached Figure Description
[0015] Figure 1 This is a perspective view of a cooling device for the production of large-size PE pipes according to this application.
[0016] Figure 2 This is a perspective view of the air outlet component of this application.
[0017] Figure 3 This application is Figure 2 A magnified view of a portion of region A in the middle.
[0018] Figure 4 This is a perspective view of the air outlet component of this application from another angle.
[0019] Figure 5 This is a perspective view of the suction component of this application.
[0020] Figure 6 This is a front view of the suction component of this application.
[0021] Figure 7 This is a perspective view of the outer wall cooling component of this application.
[0022] Figure 8 This is a perspective view of the internal components of the cooling box in this application.
[0023] The diagram shows: a cooling device 10 for large-size PE pipe production, an outer wall cooling component 20, a cooling box 21, an annular cooling pipe 22, an axial cooling pipe 23, a through hole 24, a nozzle 25, a support frame 26, a support roller 27, an inner wall cooling component 30, an air outlet assembly 31, a fixed frame 311, a telescopic assembly 312, a first adjusting frame 3121, a second adjusting frame 3122, a scissor-type telescopic frame 3123, a telescopic drive component 3124, a guide shroud 3125, a blower assembly 313, a blower 3131, a cooling pipe 314, a suction assembly 32, a mounting frame 321, an exhaust pipe 322, an exhaust cavity 323, a fan blade 324, a drive motor 325, an extruder 40, and a fixed-length cutting device 50. Detailed Implementation
[0024] The technical solutions and effects of the embodiments of this utility model will be further described in detail below with reference to the accompanying drawings.
[0025] Please refer to Figure 1 This utility model provides a cooling device 10 for the production of large-size PE pipes, including at least one outer wall cooling component 20 and an inner wall cooling component 30. Each outer wall cooling component 20 is disposed between an extruder 40 and a fixed-length cutting device 50. The tubular preform produced by the extruder 40 passes through the interior of each outer wall cooling component 20 and reaches the fixed-length cutting device 50, thereby cooling the outer wall of the tubular preform through the outer wall cooling components 20. The inner wall cooling component 30 includes an air outlet assembly 31 and an air suction assembly 32. The air outlet assembly 31 is disposed on the discharge side of the fixed-length cutting device 50, with its air outlet facing the inner wall of the tubular preform, to blow air into the interior of the tubular preform. The air suction assembly 32 is installed on the extruder 40. The feed end of the tube is connected to the feed end of the extruder 40, so as to draw air out from the inside of the tube blank, thereby forming a cooling airflow from the air outlet component 31 to the air suction component 32 inside the tube blank; thus, the outer wall of the tube blank is cooled by the outer wall cooling component 20 located between the extruder 40 and the fixed length cutting device 50, and the inner wall cooling component 30 forms a cooling airflow from the air outlet component 31 to the air suction component 32 inside the tube blank to cool the inner wall of the tube blank, thereby reducing the temperature difference between the inner and outer walls during the cooling process of the tube blank, reducing the accumulation of residual stress inside the tube blank, thereby improving the comprehensive mechanical properties of the PE pipe and extending its service life.
[0026] Please refer to Figures 2 to 4Furthermore, the air outlet assembly 31 includes a fixed frame 311, at least one telescopic group 312, and at least one air blowing group 313. The bottom of the fixed frame 311 is located on the discharge side of the fixed-length cutting device 50 and maintains a predetermined distance from the fixed-length cutting device 50. The fixed end of the first telescopic group 312 is connected to the top of the fixed frame 311, and the fixed end of the subsequent telescopic group 312 is connected to the telescopic end of the previous telescopic group 312. The fixed end of the air blowing group 313 is installed on the telescopic end of the last telescopic group 312, and the air outlet ends are all directly facing the opening of the tubular blank to deliver air into the interior of the tubular blank.
[0027] In this embodiment, the mounting bracket 311 is fixed to the ground by anchor bolts to provide a stable support base and ensure that the air outlet assembly 31 remains stable during operation.
[0028] Please refer to Figures 2 to 4 Furthermore, each telescopic assembly 312 includes a first adjusting frame 3121, a second adjusting frame 3122, a scissor-type telescopic frame 3123, and two telescopic drive members 3124. The first adjusting frame 3121 is connected to the top of the fixed frame 311 or the second adjusting frame 3122 of the adjacent telescopic assembly 312. The two ends of the scissor-type telescopic frame 3123 are respectively connected to the first adjusting frame 3121 and the second adjusting frame 3122, so that the distance between the second adjusting frame 3122 and the first adjusting frame 3121 is adjustable. The fixed ends of the two telescopic drive members 3124 are respectively disposed at the two ends of the second adjusting frame 3122, and the telescopic ends are connected to the scissor-type telescopic frame 3124. 3. Connection, used to drive the scissor-type telescopic frame 3123 to generate telescopic deformation through the telescopic drive member 3124; specifically, under the drive of the telescopic drive member 3124 (e.g., electric push rod or hydraulic cylinder), the scissor-type telescopic frame 3123 can realize the smooth movement of the second adjustment frame 3122, so as to adjust the distance between the air outlet end of the air blowing group 313 and the end of the tubular blank through the synchronous telescopic extension of each telescopic group 312, thereby enabling the air blowing group 313 to move synchronously with the output of the tubular blank, thereby ensuring a continuous, uniform and efficient cooling effect on the inner wall of the tubular blank during the dynamic production process in which the length of the tubular blank changes continuously.
[0029] In this embodiment, the scissor-type telescopic frame is composed of multiple sets of scissor units that are sequentially hinged along the telescopic direction. Each set of scissor units consists of two scissor arms of equal length that are cross-hinged at the center to form an "X" shape. The hinge point is achieved by a pin that passes through both scissor arms. Furthermore, between two adjacent sets of scissor units, the upper end of the previous set of scissor units is hinged to the lower end of the next set of scissor units by a pin.
[0030] In this embodiment, the air outlet assembly 31 also includes a controller (e.g., a programmable logic controller), which is electrically connected to the telescopic drive 3124 of each telescopic group 312. The controller is used to control each telescopic group 312 to perform synchronous telescopic movement at a predetermined cycle according to parameters pre-input by the operator, so that the air outlet end of the air blowing group 313 can move synchronously with the output of the tubular blank.
[0031] Please refer to Figures 2 to 4 Furthermore, each telescopic assembly also includes a deflector 3125, the two ends of which are connected to the first adjustment frame 3121 and the second adjustment frame 3122 respectively, and surround the scissor telescopic frame 3123 to guide airflow.
[0032] In this embodiment, the air deflector 3125 is made of a flexible material, such as abrasion-resistant rubber, so that it can fold or unfold as the scissor lift 3123 extends and retracts, always maintaining a sealed guide for the cooling airflow and preventing airflow leakage at the extension joint.
[0033] Please refer to Figures 2 to 4 Furthermore, the air blowing assembly 313 includes two air blowers 3131, which are symmetrically mounted on the second adjustment frame of the last telescopic assembly, with their air outlets facing the inner wall of the tubular blank to deliver air into the interior of the tubular blank. Specifically, the symmetrical arrangement of the two air blowers 3131 ensures the balance of air force acting on the inner wall of the tubular blank, preventing the tubular blank from swaying or vibrating during the cooling process due to unilateral air force.
[0034] Please refer to Figures 2 to 4 Furthermore, the air outlet assembly 31 also includes a cooling pipe 314, which is coiled around the top of the fixing frame 311 and connected to an external refrigeration device to reduce the temperature of the air flowing through the cooling pipe 314. Specifically, the air drawn away by the blower 3131 undergoes heat exchange when flowing through the cooling pipe 314, so that the air is fully pre-cooled before entering the blower 3131, thereby reducing the temperature of the air blown into the tubular blank, enhancing the heat exchange efficiency between the cooling airflow and the inner wall of the tubular blank, and reducing the temperature of the inner wall of the tubular blank more quickly, thus improving the overall cooling effect and product quality.
[0035] Please refer to Figure 5 and Figure 6Furthermore, the suction assembly 32 includes a mounting frame 321, a suction pipe 322, a suction chamber 323, a fan blade 324, and a drive motor 325. The mounting frame 321 is located at the feed end of the extruder 40, the suction chamber 323 is located on the mounting frame 321, the fan blade 324 is rotatably mounted inside the suction chamber 323, the fixed end of the drive motor 325 is mounted on the mounting frame 321, the drive end extends into the suction chamber 323 and is drivenly connected to the fan blade 324, one end of the suction pipe 322 is connected to the air inlet end of the suction chamber 323, and the other end is connected to the feed end of the extruder 40 and aligned with the center inside the tubular preform, so that when the drive motor 325 drives the fan blade 324 to rotate, the air inside the tubular preform, together with a small amount of ambient air sucked in from the feed port, is extracted, forming a stable negative pressure cooling airflow inside the tubular preform.
[0036] Please refer to Figure 7 and Figure 8 Furthermore, each outer wall cooling component 20 includes a cooling box 21, two annular cooling pipes 22, and at least two axial cooling pipes 23. The cooling box 21 is located between the extruder 40 and the fixed-length cutting device 50, and has through holes 24 at both ends for the tubular blank to pass through. The two annular cooling pipes 22 are respectively located on the inner wall of the cooling box 21 near both ends and are coaxially arranged with the through holes 24. Each axial cooling pipe 23 is evenly distributed along the circumference of the annular cooling pipes 22, and is connected to the two annular cooling pipes 22 at both ends, so that the annular cooling pipes 22 and the axial cooling pipes 23 together form a closed cooling circuit around the tubular blank. One of the annular cooling pipes 22 is connected to an external liquid supply device so that the coolant circulates in the cooling circuit. Each axial cooling pipe 23 has multiple nozzles 25 evenly arranged on the side facing the tubular blank, which are used to evenly spray the coolant onto the outer wall of the tubular blank for cooling.
[0037] Please refer to Figure 7 and Figure 8 Furthermore, each outer wall cooling component 20 also includes at least two support frames 26. Each support frame 26 is installed inside the cooling box 21 and is symmetrically arranged on both sides of the tubular blank. Each support frame 26 has at least one support roller 27 on its top, and each support roller 27 is rotatably mounted on the top of the support frame 26 to support the outer wall of the tubular blank. Specifically, during the cooling process, the high-temperature tubular blank is still in a plastic state with low rigidity. Under the action of its own weight and traction force, it is prone to sagging deformation. The support frame 26 and the support roller 27 on it provide necessary physical support for the tubular blank. At the same time, the rotatable support roller 27 transforms the sliding friction between the outer wall of the tubular blank and the support frame 26 into rolling friction, which can reduce traction resistance and effectively prevent the outer wall of the tubular blank from being scratched by friction.
[0038] Example 1: Working process of cooling device 10 for large-size PE pipe production
[0039] In operation, the cooling device for large-size PE pipe production of this utility model first moves the high-temperature tubular preform produced by the extruder 40 through one or more external wall cooling components and towards the fixed-length cutting device 50 under the pull of the traction mechanism. During this process, the external wall cooling components are activated, and the closed loop formed by its annular cooling pipe and axial cooling pipe sprays coolant evenly onto the outer wall of the tubular preform through the nozzle for efficient cooling. To simultaneously cool the inner wall of the tubular preform, the internal wall cooling components of the device are activated at the same time: the air outlet component located on the discharge side of the fixed-length cutting device 50 blows the cooling airflow into the interior of the tubular preform, while the suction component installed at the feed end of the extruder 40 continuously draws air, thereby forming a stable negative pressure cooling airflow flowing from the air outlet to the suction component throughout the entire moving tubular preform, directly carrying away the heat from the inner wall.
[0040] During the cooling process, each scissor-type telescopic frame 3123 extends smoothly under the drive of the telescopic drive component 3124, so that the air outlet end of the air blowing group 313 can move synchronously with the end of the tubular parison. Thus, throughout the entire dynamic extrusion process of the tubular parison, the cooling airflow is always blown in from its end temperature, so that the inner wall of the tubular parison can be covered by a continuous and stable cooling airflow, thereby reducing the temperature difference between the inner and outer walls of the tubular parison.
[0041] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A cooling device for the production of large-size PE pipes, characterized in that, The device includes at least one outer wall cooling component and an inner wall cooling component. Each outer wall cooling component is disposed between the extruder and the fixed-length cutting device. The tubular preform produced by the extruder passes through the interior of each outer wall cooling component and reaches the fixed-length cutting device to cool the outer wall of the tubular preform. The inner wall cooling component includes an air outlet component and an air suction component. The air outlet component is disposed on the discharge side of the fixed-length cutting device, and its air outlet end faces the inner wall of the tubular preform to blow air into the interior of the tubular preform. The air suction component is installed at the feed end of the extruder, and its air extraction end is connected to the feed end of the extruder to extract air from the interior of the tubular preform, thereby forming a cooling airflow flowing from the air outlet component to the air suction component inside the tubular preform.
2. The cooling device for large-size PE pipe production as described in claim 1, characterized in that, The air outlet assembly includes a fixed frame, at least one telescopic group, and a blowing group. The bottom of the fixed frame is located on the discharge side of the fixed-length cutting device and maintains a predetermined distance from the fixed-length cutting device. The fixed end of the first telescopic group is connected to the top of the fixed frame, and the fixed end of the subsequent telescopic group is connected to the telescopic end of the previous telescopic group. The fixed end of the blowing group is installed on the telescopic end of the last telescopic group, and the air outlet is directly facing the opening of the tubular blank to deliver air into the interior of the tubular blank.
3. The cooling device for large-size PE pipe production as described in claim 2, characterized in that, Each telescopic assembly includes a first adjusting frame, a second adjusting frame, a scissor-type telescopic frame, and two telescopic drive components. The first adjusting frame is connected to the top of the fixed frame or the second adjusting frame of the adjacent telescopic assembly. The two ends of the scissor-type telescopic frame are respectively connected to the first adjusting frame and the second adjusting frame so that the distance between the second adjusting frame and the first adjusting frame is adjustable. The fixed ends of the two telescopic drive components are respectively set at the two ends of the second adjusting frame, and the telescopic ends are connected to the scissor-type telescopic frame, which is used to drive the scissor-type telescopic frame to produce telescopic deformation through the telescopic extension and retraction of the telescopic drive components.
4. The cooling device for large-size PE pipe production as described in claim 3, characterized in that, Each telescopic assembly also includes a flow deflector, the two ends of which are connected to the first adjustment frame and the second adjustment frame respectively, and surround the scissor-type telescopic frame to guide airflow.
5. The cooling device for large-size PE pipe production as described in claim 4, characterized in that, The air blowing assembly includes two air blowers, which are symmetrically installed on the second adjustment frame of the last telescopic assembly, and the air outlets of both air blowers face the inner wall of the tubular blank to deliver air into the interior of the tubular blank.
6. The cooling device for large-size PE pipe production as described in claim 5, characterized in that, The air outlet assembly also includes a cooling pipe, which is coiled around the top of the mounting frame and connected to an external refrigeration device to reduce the temperature of the air flowing through the cooling pipe.
7. The cooling device for large-size PE pipe production as described in claim 1, characterized in that, The suction assembly includes a mounting frame, a suction pipe, a suction chamber, fan blades, and a drive motor. The mounting frame is located at the feed end of the extruder, the suction chamber is mounted on the mounting frame, the fan blades are rotatably mounted in the suction chamber, the fixed end of the drive motor is mounted on the mounting frame, the drive end extends into the suction chamber and is driven by the fan blades, one end of the suction pipe is connected to the air inlet of the suction chamber, and the other end is connected to the feed end of the extruder and aligned with the center of the tubular preform. When the drive motor drives the fan blades to rotate, the air inside the tubular preform, along with a small amount of ambient air drawn in from the feed inlet, is extracted, forming a stable negative pressure cooling airflow inside the tubular preform.
8. The cooling device for large-size PE pipe production as described in claim 7, characterized in that, Each outer wall cooling component includes a cooling box, two annular cooling pipes, and at least two axial cooling pipes. The cooling box is located between the extruder and the fixed-length cutting equipment, and has through holes at both ends for the tubular blank to pass through. The two annular cooling pipes are respectively located in the cooling box near both ends and are coaxially arranged with the through holes. Each axial cooling pipe is evenly distributed along the circumference of the annular cooling pipes, and each end is connected to the two annular cooling pipes, so that the annular cooling pipes and the axial cooling pipes together form a closed cooling circuit around the tubular blank. One of the annular cooling pipes is connected to an external liquid supply device to allow the coolant to circulate in the cooling circuit. Multiple nozzles are evenly arranged on the side of each axial cooling pipe facing the tubular blank to uniformly spray the coolant onto the outer wall of the tubular blank for cooling.
9. The cooling device for large-size PE pipe production as described in claim 8, characterized in that, Each outer wall cooling component also includes at least two support frames, each support frame is installed inside the cooling box and is symmetrically arranged on both sides of the tubular blank. Each support frame has at least one support roller at its top, and each support roller is rotatably installed on the top of the support frame to support the outer wall of the tubular blank.