A molding method for reducing uneven crystallization of a PEKK thick-walled hollow pipe

Abstract

The application discloses a molding method for reducing the uneven crystallization of a PEKK thick-wall hollow pipe, and relates to the technical field of battery structures, which comprises the following steps: in the pipe molding process, the cooling path is adjusted, so that the cooling rate of the pipe in the radial direction tends to be consistent, thereby reducing the difference in the crystallinity in the wall thickness direction and reducing the cloud pattern or atomization phenomenon. The application adjusts the cooling path accurately to make the radial cooling rate of the pipe tend to be consistent, effectively solves the problem of the great difference in the crystallinity distribution in the wall thickness direction caused by uneven cooling in the traditional process, makes the PEKK macromolecular chains crystallize synchronously along the wall thickness direction under similar kinetic conditions, completely reduces or eliminates optical defects such as cloud patterns, local atomization and light spot scattering, and significantly improves the light transmission and appearance uniformity of the pipe, so that the high-end application scenarios such as chromatographic column pipes and optical detection cavities with strict requirements on high transparency and low scattering can be stably met.

Description

Technical Field

[0001] This invention relates to the field of battery structure technology, specifically to a molding method for reducing the non-uniformity of crystallization in PEKK thick-walled hollow tubular materials. Background Technology

[0002] Polyetherketoneketone (PEKK), a high-performance semi-crystalline polyaryletherketone (PAEK) special engineering plastic, has become a core material in key fields such as aerospace, high-end medical, precision analysis, and semiconductor fluid control due to its comprehensive properties including high temperature resistance, chemical corrosion resistance, high specific strength, dimensional stability, low moisture absorption, and excellent biocompatibility. In scenarios such as chromatographic analysis, high-pressure fluid transportation, and online detection sensing, PEKK thick-walled hollow tubing, with its combination of structural strength, chemical inertness, and optical visibility, has become an ideal replacement for traditional metals, glass, and ordinary engineering plastics. It is especially suitable for high-precision chromatographic column tubes, high-pressure fluid pipelines, and optical detection chambers, where stringent requirements exist for wall thickness uniformity, crystallinity consistency, light transmittance, and dimensional stability.

[0003] Polyetherketoneketone (PEKK), a high-performance semi-crystalline polyaryletherketone (PAEK) special engineering plastic, has become a core material in key fields such as aerospace, high-end medical, precision analysis, and semiconductor fluid control due to its comprehensive properties including high temperature resistance, chemical corrosion resistance, high specific strength, dimensional stability, low moisture absorption, and excellent biocompatibility. In scenarios such as chromatographic analysis, high-pressure fluid transportation, and online detection sensing, PEKK thick-walled hollow tubing, with its combination of structural strength, chemical inertness, and optical visibility, has become an ideal replacement for traditional metals, glass, and ordinary engineering plastics. It is especially suitable for high-precision chromatographic column tubes, high-pressure fluid pipelines, and optical detection chambers, where stringent requirements exist for wall thickness uniformity, crystallinity consistency, light transmittance, and dimensional stability.

[0004] The aforementioned crystallization inhomogeneity directly leads to a series of product defects that are difficult to improve through conventional means: First, optical defects such as cloud-like patterns, localized fogging, and light spot scattering appear on the surface and inside of the product, significantly reducing light transmittance and failing to meet the requirements for use of optically visible components such as transparent chromatographic column tubes; Second, the crystallization gradient causes internal stress concentration, resulting in decreased dimensional stability of the tube, warping deformation, and uneven inner wall roughness, affecting the reliability of subsequent assembly and use; Third, crystallization differences cause fluctuations in the circumferential and axial properties of the tube, reducing structural consistency and fatigue resistance. Summary of the Invention

[0005] The purpose of this invention is to provide a molding method for reducing the non-uniformity of crystallization in PEKK thick-walled hollow pipes, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a molding method for reducing the non-uniformity of crystallization in PEKK thick-walled hollow pipes, comprising adjusting the cooling path during the pipe molding process to make the cooling rate of the pipe in the radial direction more uniform, thereby reducing the difference in crystallinity in the wall thickness direction and reducing cloud-like patterns or atomization phenomena.

[0007] Preferably, the controlled cooling path is achieved through segmented cooling, dividing the entire process of the pipe from the mold outlet to the final shaping into multiple segments with different cooling intensities and functions. Through the sequential synergistic effect of each segment, the pipe is gradually guided from a high-temperature molten state to a stable solid state, avoiding problems such as sudden cooling, excessive internal and external temperature differences, and obvious crystallization gradients caused by a single cooling method. This makes the cooling process more in line with the PEKK crystallization kinetics, achieving controllable and uniform crystallization behavior.

[0008] Preferably, the segmented cooling sequentially includes a non-contact buffer zone, a weak cooling zone, and an enhanced cooling zone. The non-contact buffer zone is a space where the tube blank and the cooling medium do not directly contact each other, used to delay the rapid cooling of the outer surface of the tube blank. The non-contact buffer zone is a space where the tube blank does not directly contact the external cooling medium; within this zone, the tube blank relies solely on natural convection and radiation for slow heat dissipation, effectively delaying excessively rapid cooling and premature solidification of the outer surface of the tube blank, preventing the outer wall from prematurely crystallizing and forming a rigid surface layer due to sudden cooling, thus creating conditions for simultaneous cooling of the inner and outer layers. The weak cooling zone uses low-temperature airflow or low-temperature water mist for low-intensity cooling. The weak cooling zone follows the buffer zone, using a gentle, low-temperature airflow or a small amount of low-temperature water mist to cool the outer surface of the pipe in a low-intensity, uniform manner. This allows the pipe temperature to drop steadily and gradually enter the crystallization temperature range, ensuring that the crystallization of the inner and outer layers begins synchronously. The enhanced cooling zone uses air cooling, water cooling, or air-water combined cooling for rapid shaping. The enhanced cooling zone is the final shaping section, using efficient air cooling, spray water cooling, or air-water mixed combined cooling to rapidly and fully cool the pipe that has completed the initial crystallization, allowing the pipe to quickly solidify and shape, locking in a uniform microstructure and dimensional morphology, and ensuring product stability.

[0009] Preferably, by reducing the initial cooling intensity of the outer surface, the cooling rate of the inner and outer layers of the pipe is balanced. By reducing the initial cooling intensity of the outer surface of the pipe, the outer wall is prevented from being subjected to strong cooling immediately after leaving the mold and cooling down rapidly. This moderately slows down the cooling rate of the outer wall, making it close to the natural cooling rate formed by the lag in heat conduction of the inner wall. This significantly reduces the temperature difference and cooling rate difference between the inner and outer layers of the pipe, allowing the PEKK macromolecular chains to arrange and crystallize under similar kinetic conditions along the wall thickness direction, truly achieving balanced cooling and synchronous crystallization of the inner and outer layers.

[0010] Preferably, the outer and inner walls of the pipe are cooled and regulated simultaneously through coordinated cooling of the inner and outer sides, thereby reducing the radial temperature gradient. By adopting the coordinated cooling strategy of the inner and outer sides, while cooling and regulating the outer wall of the pipe, matching cooling is simultaneously implemented on the inner wall of the pipe, so that the inner and outer walls of the pipe can obtain controllable and balanced heat exchange conditions at the same time, which significantly shortens the heat transfer lag time in the wall thickness direction and effectively weakens the radial temperature gradient.

[0011] Preferably, the inner and outer synergistic cooling is achieved by introducing a cooling medium into the hollow core rod. A constant-temperature or variable-temperature cooling medium is continuously introduced into the hollow core rod, allowing the cooling medium to flow along the core rod channel and exchange heat with the inner wall of the core rod. Then, it exchanges heat indirectly with the inner wall of the pipe through the outer wall of the core rod, thereby achieving gentle, stable, and controllable cooling of the inner wall of the pipe. This, combined with the cooling of the outer wall, forms a bidirectional synergistic control system.

[0012] Preferably, the wall thickness of the PEKK pipe is greater than 3mm. Such thick-walled products are prone to significant radial temperature gradients and crystallization gradients in traditional cooling processes, which is a common scenario for defects such as uneven crystallization, clouding, and fogging.

[0013] Preferably, the method enables the PEKK pipe to have high light transmittance. This method achieves uniform crystallization along the wall thickness direction of the PEKK pipe, with small and consistent crystal size distribution, significantly reducing the refractive index difference between the crystalline and amorphous regions, reducing light scattering and light loss. Therefore, the PEKK hollow pipe can have excellent high light transmittance, with a clear and transparent appearance, free from cloudiness, haze, and spots, which can meet the high requirements of high optical transmittance for high-end application scenarios such as chromatographic column tubes, optical fluid cavities, and transparent detection pipelines.

[0014] A molding method for reducing the uneven crystallization of PEKK thick-walled hollow pipes includes the following steps: S1 melt extrusion molding: PEKK raw material is heated to a molten state and formed into a thick-walled hollow tube blank with a wall thickness greater than 3mm through an extrusion die and a mandrel; S2 Cooling Path Overall Control: After the tube blank leaves the mold and before it is fully shaped, the cooling process and cooling intensity are precisely controlled to construct a cooling path that matches the thick-walled structure, so that the radial cooling rate of the tube tends to be consistent, reducing the difference in crystallinity in the wall thickness direction and suppressing cloud-like patterns and atomization phenomena. S3 segmented cooling implementation: The cooling process is divided into non-contact buffer zone, weak cooling zone and enhanced cooling zone. Through the sequential synergistic effect of multiple zones, a smooth transition from high temperature melt to solid is achieved. S4 segmented and zoned cooling: In the non-contact buffer zone, natural heat dissipation without contact slows down the rapid cooling of the outer wall; in the weak cooling zone, low-temperature airflow or low-temperature water mist is used for low-intensity uniform cooling, so that the crystallization of the inner and outer layers tends to be synchronized; in the enhanced cooling zone, air cooling, water cooling or air-water combined cooling is used to achieve rapid solidification and shaping. S5 Initial Cooling Intensity Control: Reduce the initial cooling intensity of the outer surface of the tube blank, slow down the cooling rate of the outer wall, and make the cooling rate of the inner and outer layers and the crystallization process tend to be balanced; S6 Synergistic Cooling of Inner and Outer Sides: The inner wall is cooled synchronously by introducing a cooling medium into the hollow core rod, which matches the cooling of the outer wall, reduces the radial temperature gradient, and achieves uniform cooling across the entire wall thickness. S7 Product Shaping and Acquisition: After uniform cooling and crystallization control, PEKK thick-walled hollow pipes with uniform crystallization, no cloudiness, high light transmittance, and stable dimensions are obtained.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This molding method, designed to reduce the non-uniform crystallization of PEKK thick-walled hollow pipes, precisely controls the cooling path to ensure a uniform radial cooling rate. This effectively solves the problem of uneven crystallinity distribution along the wall thickness caused by uneven cooling in traditional processes. It allows PEKK macromolecular chains to crystallize synchronously along the wall thickness under similar kinetic conditions, thoroughly reducing or eliminating optical defects such as cloud-like patterns, localized fogging, and light spot scattering. This significantly improves the light transmittance and appearance uniformity of the pipe, and can reliably meet the stringent requirements of high transparency and low scattering in high-end applications such as chromatographic column tubes and optical detection chambers.

[0016] This molding method, designed to reduce the non-uniform crystallization of PEKK thick-walled hollow pipes, achieves synchronized cooling and shrinkage of the inner and outer layers of the PEKK pipe through comprehensive control of segmented cooling, delayed strong cooling, and coordinated cooling of the inner and outer sides. This significantly alleviates the accumulation of internal stress caused by the crystallization gradient, preventing problems such as warping, dimensional drift, and uneven inner wall roughness in the product. It effectively improves the dimensional accuracy, structural consistency, and long-term stability of the pipe, ensuring the reliability of subsequent precision assembly, high-pressure fluid transportation, and online testing processes.

[0017] This molding method, designed to reduce the uneven crystallization of thick-walled PEKK hollow tubing, specifically addresses the technical challenges of large cooling lag, significant temperature differences, and difficulty in synchronized crystallization in traditional molding processes for PEKK hollow tubing with a wall thickness greater than 3mm. While ensuring the strength of the thick-walled structure, it achieves uniform crystallization and high light transmittance, enabling thick-walled PEKK tubing to fully replace traditional metal, glass, and ordinary engineering plastic components. This allows for successful application in fields with extremely high requirements for material performance and structural consistency, such as aerospace, high-end medical, precision analysis, and semiconductor fluid control, significantly improving the industrialization and high-end application level of PEKK materials. Attached Figure Description

[0018] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] like Figure 1 As shown, this embodiment describes a molding method for reducing the non-uniformity of crystallization in PEKK thick-walled hollow pipes. During pipe molding, the cooling path is adjusted to ensure a uniform cooling rate in the radial direction, thereby reducing crystallinity differences in the wall thickness direction and minimizing cloud-like patterns or fogging. By precisely controlling the cooling process and intensity after the pipe leaves the mold, a cooling path matching the thick-walled structure is constructed. This ensures that the cooling rates at various locations along the radial direction of the wall thickness from the outer wall to the inner wall are as close as possible, and temperature changes are synchronized. This reduces problems such as asynchronous crystallization and uneven crystal distribution caused by differences in cooling rates, significantly reducing the crystallinity difference in the wall thickness direction. It fundamentally suppresses optical defects such as cloud-like patterns, localized whitening, fogging, and light scattering caused by non-uniform crystallization, improving the uniformity of the product's appearance and optical transmittance.

[0022] Specifically, the cooling path is controlled through segmented cooling. The entire process of the pipe from the mold outlet to the final shaping is divided into multiple sections with different cooling intensities and functions. Through the sequential synergistic effect of each section, the pipe is gradually guided from a high-temperature molten state to a stable solid state. This avoids problems such as sudden cooling, excessive internal and external temperature differences, and obvious crystallization gradients caused by a single cooling method. The cooling process is made to better conform to the crystallization kinetics of PEKK, and the crystallization behavior is made controllable and uniform.

[0023] Furthermore, the segmented cooling system includes a non-contact buffer zone, a weak cooling zone, and an enhanced cooling zone. The non-contact buffer zone is a space where the tube blank and the cooling medium do not directly contact each other, used to slow down the rapid cooling of the outer surface of the tube blank. In this zone, the tube blank relies solely on natural convection and radiation for slow heat dissipation, effectively delaying excessively rapid cooling and premature solidification of the outer surface, preventing the outer wall from prematurely crystallizing and forming a rigid surface layer due to sudden cooling, thus creating conditions for simultaneous cooling of the inner and outer layers. The weak cooling zone uses low-temperature airflow or low-temperature water mist for low-intensity cooling. The cooling zone follows the buffer zone, using a gentle, low-temperature airflow or a small amount of low-temperature water mist to cool the outer surface of the pipe in a low-intensity, uniform manner. This allows the pipe temperature to drop steadily and gradually enter the crystallization temperature range, ensuring that the crystallization of the inner and outer layers begins synchronously. The enhanced cooling zone uses air cooling, water cooling, or air-water combined cooling for rapid shaping. The enhanced cooling zone is the final shaping section, using efficient air cooling, spray water cooling, or air-water mixed combined cooling to rapidly and fully cool the pipe that has completed the initial crystallization, allowing the pipe to quickly solidify and shape, locking in a uniform microstructure and dimensional form, and ensuring the stability of the product.

[0024] Furthermore, by reducing the initial cooling intensity of the outer surface, the cooling rate of the inner and outer layers of the pipe is balanced. By reducing the initial cooling intensity of the outer surface of the pipe, the outer wall is prevented from being subjected to strong cooling immediately after leaving the mold and cooling down rapidly. This moderately slows down the cooling rate of the outer wall, making it close to the natural cooling rate formed by the lag in heat conduction of the inner wall. This significantly reduces the temperature difference and cooling rate difference between the inner and outer layers of the pipe, allowing the PEKK macromolecular chains to arrange and crystallize under similar kinetic conditions along the wall thickness direction, truly achieving balanced cooling and synchronous crystallization of the inner and outer layers.

[0025] Furthermore, by simultaneously cooling and regulating the outer and inner walls of the pipe through coordinated internal and external cooling, the radial temperature gradient is reduced. By adopting a coordinated internal and external cooling strategy, while cooling and regulating the outer wall of the pipe, matching cooling is simultaneously implemented on the inner wall of the pipe. This allows the inner and outer walls of the pipe to obtain controllable and balanced heat exchange conditions, significantly shortening the heat transfer lag time in the wall thickness direction, effectively weakening the radial temperature gradient, and making the temperature field more flat throughout the entire wall thickness range. This fundamentally improves the problems of uneven crystallization, internal stress concentration, and clouding caused by unidirectional cooling.

[0026] Furthermore, the coordinated cooling of the inner and outer sides is achieved by introducing a cooling medium into the hollow mandrel. A constant-temperature or variable-temperature cooling medium is continuously introduced into the hollow mandrel, allowing the cooling medium to flow along the mandrel's flow channel and exchange heat with the inner wall of the mandrel. Then, it exchanges heat indirectly with the inner wall of the tube through the outer wall of the mandrel. This achieves gentle, stable, and controllable cooling of the inner wall of the tube. Combined with the cooling of the outer wall, this forms a two-way coordinated control system, enabling the thick-walled tube to achieve a uniform and synchronous cooling effect throughout its radial thickness, further improving crystallization consistency and dimensional accuracy.

[0027] Furthermore, PEKK pipes have a wall thickness greater than 3mm. In traditional cooling processes, these thick-walled products are prone to significant radial temperature and crystallization gradients, which are common causes of defects such as uneven crystallization, clouding, and atomization. This invention can effectively solve the technical problems of slow heat transfer, large temperature difference, and asynchronous crystallization in thick-walled structures by precisely controlling the cooling path, so that PEKK pipes with a wall thickness of 3mm or more can still maintain good structural uniformity, clear appearance, and dimensional stability.

[0028] Furthermore, the method enables the produced PEKK tubing to possess high light transmittance. Because this method achieves uniform crystallization along the wall thickness direction of the PEKK tubing, with small and consistent crystalline region sizes, it significantly reduces the refractive index difference between crystalline and amorphous regions, thereby reducing light scattering and light loss. Therefore, the produced PEKK hollow tubing possesses excellent high light transmittance, with a clear and transparent appearance, free from cloudiness, haze, and blemishes. This meets the requirements of high-end applications with extremely high optical transmittance, such as chromatographic column tubes, optical fluid cavities, and transparent detection pipelines, greatly expanding the application scope of PEKK thick-walled tubing in precision analysis, medical testing, and high-end fluid equipment.

[0029] A molding method for reducing the uneven crystallization of PEKK thick-walled hollow pipes includes the following steps: S1 melt extrusion molding: PEKK raw material is heated to a molten state and formed into a thick-walled hollow tube blank with a wall thickness greater than 3mm through an extrusion die and a mandrel; S2 Cooling Path Overall Control: After the tube blank leaves the mold and before it is fully shaped, the cooling process and cooling intensity are precisely controlled to construct a cooling path that matches the thick-walled structure, so that the radial cooling rate of the tube tends to be consistent, reducing the difference in crystallinity in the wall thickness direction and suppressing cloud-like patterns and atomization phenomena. S3 segmented cooling implementation: The cooling process is divided into non-contact buffer zone, weak cooling zone and enhanced cooling zone. Through the sequential synergistic effect of multiple zones, a smooth transition from high temperature melt to solid is achieved. S4 segmented and zoned cooling: In the non-contact buffer zone, natural heat dissipation without contact slows down the rapid cooling of the outer wall; in the weak cooling zone, low-temperature airflow or low-temperature water mist is used for low-intensity uniform cooling, so that the crystallization of the inner and outer layers tends to be synchronized; in the enhanced cooling zone, air cooling, water cooling or air-water combined cooling is used to achieve rapid solidification and shaping. S5 Initial Cooling Intensity Control: Reduce the initial cooling intensity of the outer surface of the tube blank, slow down the cooling rate of the outer wall, and make the cooling rate of the inner and outer layers and the crystallization process tend to be balanced; S6 Synergistic Cooling of Inner and Outer Sides: The inner wall is cooled synchronously by introducing a cooling medium into the hollow core rod, which matches the cooling of the outer wall, reduces the radial temperature gradient, and achieves uniform cooling across the entire wall thickness. S7 Product Shaping and Acquisition: After uniform cooling and crystallization control, PEKK thick-walled hollow pipes with uniform crystallization, no cloudiness, high light transmittance, and stable dimensions are obtained.

[0030] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A molding method for reducing the uneven crystallization of PEKK thick-walled hollow pipes, characterized in that: During the pipe forming process, by controlling the cooling path, the cooling rate of the pipe in the radial direction tends to be uniform, thereby reducing the crystallinity difference in the wall thickness direction and reducing cloud-like patterns or atomization phenomena.

2. The molding method for reducing the uneven crystallization of PEKK thick-walled hollow pipes according to claim 1, characterized in that: The controlled cooling path is achieved through segmented cooling.

3. The molding method for reducing the uneven crystallization of PEKK thick-walled hollow pipes according to claim 2, characterized in that: The segmented cooling includes a non-contact buffer zone, a weak cooling zone, and an enhanced cooling zone. The non-contact buffer zone is a space where the tube blank and the cooling medium do not have direct contact, and is used to delay the rapid cooling of the outer surface of the tube blank. The weak cooling zone uses low-temperature airflow or low-temperature water mist for low-intensity cooling. The enhanced cooling zone uses air cooling, water cooling, or air-water combined cooling methods for rapid shaping.

4. The molding method for reducing the uneven crystallization of PEKK thick-walled hollow pipes according to claim 1, characterized in that: By reducing the initial cooling intensity of the outer surface, a balance in the cooling rate between the inner and outer layers of the pipe is achieved.

5. The molding method for reducing the uneven crystallization of PEKK thick-walled hollow pipes according to claim 1, characterized in that: By coordinating cooling on both the inner and outer sides, the outer and inner walls of the pipe are simultaneously cooled and regulated, thereby reducing the radial temperature gradient.

6. The molding method for reducing the uneven crystallization of PEKK thick-walled hollow pipes according to claim 5, characterized in that: The coordinated cooling of the inner and outer sides is achieved by introducing a cooling medium into the hollow core rod.

7. The molding method for reducing the uneven crystallization of PEKK thick-walled hollow pipes according to claim 1, characterized in that: The wall thickness of the PEKK pipe is greater than 3mm.

8. The molding method for reducing the uneven crystallization of PEKK thick-walled hollow pipes according to claim 1, characterized in that: The method enables the produced PEKK pipes to have high light transmittance.

9. A molding method for reducing the uneven crystallization of PEKK thick-walled hollow pipes according to claims 1-8, characterized in that: Includes the following steps: S1 melt extrusion molding: PEKK raw material is heated to a molten state and formed into a thick-walled hollow tube blank with a wall thickness greater than 3mm through an extrusion die and a mandrel; S2 Cooling Path Overall Control: After the tube blank leaves the mold and before it is fully shaped, the cooling process and cooling intensity are precisely controlled to construct a cooling path that matches the thick-walled structure, so that the radial cooling rate of the tube tends to be consistent, reducing the difference in crystallinity in the wall thickness direction and suppressing cloud-like patterns and atomization phenomena. S3 segmented cooling implementation: The cooling process is divided into non-contact buffer zone, weak cooling zone and enhanced cooling zone. Through the sequential synergistic effect of multiple zones, a smooth transition from high temperature melt to solid is achieved. S4 segmented and zoned cooling: In the non-contact buffer zone, natural heat dissipation without contact slows down the rapid cooling of the outer wall; in the weak cooling zone, low-temperature airflow or low-temperature water mist is used for low-intensity uniform cooling, so that the crystallization of the inner and outer layers tends to be synchronized; in the enhanced cooling zone, air cooling, water cooling or air-water combined cooling is used to achieve rapid solidification and shaping. S5 Initial Cooling Intensity Control: Reduce the initial cooling intensity of the outer surface of the tube blank, slow down the cooling rate of the outer wall, and make the cooling rate of the inner and outer layers and the crystallization process tend to be balanced; S6 Synergistic Cooling of Inner and Outer Sides: The inner wall is cooled synchronously by introducing a cooling medium into the hollow core rod, which matches the cooling of the outer wall, reduces the radial temperature gradient, and achieves uniform cooling across the entire wall thickness. S7 Product Shaping and Acquisition: After uniform cooling and crystallization control, PEKK thick-walled hollow pipes with uniform crystallization, no cloudiness, high light transmittance, and stable dimensions are obtained.

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