PEEK superfine grinding system and grinding method

Abstract

The invention belongs to the technical field of crushing devices and methods, and particularly relates to a PEEK superfine crushing system and method.The PEEK superfine crushing system comprises a subzero treatment box, a target jet mill, a crushing cavity, a grading impeller, a tungsten carbide target disc and a supersonic nozzle, and the grading impeller is coaxially arranged on the central axis of the crushing cavity; one end of the target jet mill is connected with a cloth bag type particle collector, and the other end of the target jet mill is connected with a low-temperature air source unit; the crushing method of the PEEK superfine crushing system comprises the following steps: S1, material pretreatment; s2, primary crushing; s3, cyclic crushing; s4, collecting a finished product; according to the invention, the crushing stability and the crushing precision of the PEEK material can be improved, and the preparation period of the PEEK superfine powder is shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of pulverization, and in particular relates to a PEEK ultrafine pulverization system and a pulverization method. Background Art

[0002] As a high-performance thermoplastic engineering plastic, polyetheretherketone (PEEK) is widely used in aerospace structural parts, medical implants, high-end electronic packaging and other fields due to its excellent mechanical strength, high temperature resistance and biocompatibility. However, the ultrafine grinding technology of PEEK has long faced multiple bottlenecks. First, PEEK has a high elongation at break and is very prone to plastic deformation during traditional mechanical grinding, resulting in increased energy consumption and low grinding efficiency; second, during conventional airflow grinding, the heat generated by the friction between PEEK particles will cause the local temperature to rise sharply, triggering PEEK oxidative degradation, thereby affecting the purity and performance stability of PEEK; third, the existing target airflow grinding technology lacks an effective dynamic grading mechanism, making it difficult to simultaneously achieve ultrafine grinding and narrow particle size distribution control, making it difficult for the resulting PEEK powder product to meet use requirements.

[0003] Chinese patent CN2754728Y discloses a cryogenic supersonic airflow mill, comprising a top cover, a discharge pipe, a nozzle, an injection pipe, a high-pressure pipe, a crushing chamber, a pre-vacuum pipe, an ionization vacuum gauge, and a rotary classifier. A vacuum jacketed housing is connected to the periphery of the crushing chamber, which is connected to the top cover. The crushing chamber and the outer vacuum jacketed housing have concentric axes. The nozzles are evenly distributed on a circumferential plane and extend into the crushing chamber at an elevation angle of 20 to 30 degrees. A wear-resistant sleeve is fixed in the crushing chamber in the direction corresponding to the nozzle injection. This patent can effectively crush elastomeric materials and facilitate material flow. The wear-resistant sleeve is used to frictionally crush the material, reducing impact wear in the crushing chamber and increasing the service life of the crusher. However, this patent maintains low temperatures only through the vacuum jacket and does not incorporate active cooling methods such as liquid nitrogen vaporization, making it difficult to continuously maintain ultra-low temperatures during the crushing process. Furthermore, this patent relies on the self-grinding of particles and the impact of the wear-resistant sleeve to achieve crushing, resulting in coarse crushing particle size and high crushing energy consumption, making it difficult to meet crushing accuracy requirements. Summary of the Invention

[0004] The purpose of the present invention is to provide a PEEK ultrafine grinding system that can reduce the PEEK grinding energy consumption and production costs, avoid oxidative degradation caused by frictional heat generation, improve the grinding stability and grinding accuracy of PEEK high-toughness heat-sensitive materials, shorten the PEEK ultrafine powder preparation cycle, and the present invention also provides a grinding method.

[0005] To achieve the above object, the technical solution of the present invention is: A PEEK ultrafine grinding system comprises a cryogenic treatment box, one end of which is connected to a target airflow pulverizer, a grinding chamber is provided in the target airflow pulverizer, a classifying impeller is rotatably provided inside the grinding chamber, the classifying impeller is arranged in a cylindrical shape as a whole, a discharge port is provided at one end of the target airflow pulverizer in cooperation with the classifying impeller, a driving motor is provided at the other end of the target airflow pulverizer in cooperation with the classifying impeller, an end of the discharge port away from the target airflow pulverizer is connected to a bag-type particle collector, a tungsten carbide target disk is fixedly provided in the grinding chamber, a supersonic nozzle is provided on one side of the grinding chamber in cooperation with the tungsten carbide target disk, one end of the supersonic nozzle extends into the grinding chamber, the other end of the supersonic nozzle penetrates the target airflow pulverizer and is connected to an air source unit, inert gas is provided inside the air source unit, liquid nitrogen is provided inside the cryogenic treatment box, a temperature sensor and a controller are provided on the grinding chamber, the temperature sensor and the controller are both electrically connected to the air source unit, and a barrel is provided at the bottom of the bag-type particle collector.

[0006] Furthermore, the pulverizing chamber is arranged in a disc shape as a whole, and the classifying impeller is coaxially arranged on the central axis of the pulverizing chamber.

[0007] Furthermore, a feed port is provided on the top of the target-type airflow mill, and one end of the feed port away from the target-type airflow mill is connected to the cryogenic treatment box.

[0008] Furthermore, one end of the cryogenic treatment box away from the target-type airflow mill is connected to a material bin.

[0009] Furthermore, an output shaft is provided on the driving motor, and one end of the output shaft away from the driving motor passes through the target-type airflow mill and is connected to the classifying impeller, and the material of the classifying impeller is titanium alloy.

[0010] Furthermore, the tungsten carbide target disc includes a crushing disc and an assembly connection block. The end face of the crushing disc is tilted to match the supersonic nozzle. A shearing edge is provided on the end face of the crushing disc. The shearing edge is serrated as a whole. The hardness of the tungsten carbide target disc is between 2200 and 2300 HV.

[0011] Furthermore, a heat-insulating layer is provided outside the barrel, and a sealing ring is provided between the discharge port and the target-type airflow mill.

[0012] A pulverization method using a PEEK ultrafine pulverization system comprises the following steps: S1. Material pretreatment The PEEK raw material is transported to a cryogenic treatment box and subjected to cryogenic treatment by staged cooling. In the first stage, the temperature is lowered from room temperature to -80-90°C at a rate of 3-5°C / min and kept at this temperature for 10-15 minutes. In the second stage, the temperature is lowered to -150--196°C at a rate of 6-8°C / min and kept at this temperature for 20-40 minutes. After the treatment is completed, the PEEK raw material is transported to the grinding chamber of the target airflow mill. S2. Initial crushing Turn on the gas source unit to spray the inert gas into the crushing chamber through the supersonic nozzle, forming a high-speed airflow with a Mach number of 0.9 to 1.5. The high-speed airflow pushes the PEEK raw material to hit the tungsten carbide target disk, and the PEEK raw material is initially crushed into PEEK particles; S3, Circular Crushing Start the drive motor, which drives the classifying impeller to rotate in the crushing chamber. The speed of the classifying impeller is controlled at 5000-20000 rpm to dynamically classify the crushed PEEK particles. During the pulverizing process, inert gas is introduced intermittently. The temperature sensor on the pulverizing chamber monitors the temperature inside the pulverizing chamber in real time and transmits the temperature signal to the controller in real time. The controller analyzes and judges the temperature signal after receiving it. When the temperature is less than -30°C, the controller sends a stop gas supply instruction to the gas source unit, and the gas source unit suspends gas supply; when the temperature is greater than or equal to -30°C, the controller sends a start gas supply instruction to the gas source unit, and the gas source unit starts and introduces inert gas until the temperature inside the pulverizing chamber drops below -30°C. PEEK ultrafine particles enter the bag-type particle collector through the discharge port, and the PEEK coarse particles are thrown back into the crushing chamber and participate in impact crushing again; S4. Finished product collection The crushed PEEK ultrafine particles are enriched in the bag-type particle collector. When the amount of PEEK ultrafine particles in the bag-type particle collector reaches 80% of the rated capacity of the bag-type particle collector, the PEEK ultrafine particles in the bag-type particle collector are discharged to the bottom barrel to complete the collection of the finished product.

[0013] Furthermore, in step S2, the inert gas is nitrogen or argon, and the temperature of the inert gas is between -50 and -60°C.

[0014] Furthermore, in step S4, nitrogen is continuously introduced into the barrel to replace the air during the unloading process.

[0015] The beneficial effects of the present invention are: The cryogenic treatment box uses liquid nitrogen to cool and embrittle the PEEK raw material, inducing grain boundary cracks inside the PEEK raw material, which can reduce the fracture toughness of the PEEK raw material; the shear edges on the surface of the tungsten carbide target can improve the PEEK raw material crushing efficiency and reduce crushing energy consumption; the gas source unit introduces inert gas into the crushing chamber through a supersonic nozzle, and combined with the cryogenic pretreatment of the cryogenic treatment box, the crushing chamber temperature is always maintained at a low temperature environment, avoiding oxidative degradation of the PEEK raw material due to frictional heat, and ensuring the purity of subsequent PEEK ultrafine particles.

[0016] The driving motor drives the classifying impeller to rotate at high speed, and the PEEK particles are screened in real time by centrifugal force. The PEEK ultrafine particles are collected through the discharge port, and the coarse PEEK particles return to the crushing chamber for recycling treatment, achieving efficient preparation of PEEK ultrafine particles and narrow particle size distribution control. The tungsten carbide target disc has a high hardness and strong impact and wear resistance, which can extend the equipment life and reduce maintenance costs.

[0017] The material bin, cryogenic treatment box, target airflow mill and bag-type particle collector are connected in sequence to form a continuous processing system, which supports large-scale production, significantly shortens the preparation cycle of PEEK ultrafine particles, and improves production efficiency; the cryogenic treatment box and the air source unit coordinate to control the process temperature, and the high-speed airflow of the supersonic nozzle can achieve precise temperature control, improve the stability of the pulverization process, and ensure that the particle size parameters and purity of PEEK ultrafine particles produced in different batches remain stable and uniform. There is no need for additional testing or adjustment of process parameters for each batch of PEEK ultrafine particles, reducing quality control costs.

[0018] The cryogenic treatment box performs cryogenic treatment on PEEK raw materials through staged cooling. In the first stage, the temperature is slowly cooled to -80~90℃ and kept warm. In the second stage, the temperature is quickly dropped to the ultra-low temperature range of -150~-196℃, allowing the PEEK raw materials to gradually adapt to the low temperature environment, avoiding instantaneous ultra-low temperature damage to its structure, and ensuring the chemical stability of the raw materials. At the same time, the ultra-low temperature environment causes the PEEK molecular chain mobility to decrease and the elongation at break to decrease, inducing uniform grain boundary cracks inside, significantly increasing brittleness, reducing fracture toughness, and reducing plastic deformation in the subsequent crushing process, thereby reducing crushing energy consumption and equipment wear. The pretreated PEEK raw materials are directly transported to the crushing chamber without the need for additional transfer or heating links, reducing the exposure time at room temperature and avoiding the decrease in brittleness due to temperature rise.

[0019] A temperature sensor in the grinding chamber is linked to a controller to monitor the temperature in real time and control the intermittent flow of inert gas. When the temperature is ≥ -30°C, inert gas at -50 to -60°C is introduced to cool the material down to below -30°C. Once the temperature reaches the target, gas supply is suspended to reduce gas consumption. This precise temperature control effectively suppresses heat accumulation caused by frictional heat generation, prevents oxidative degradation of PEEK, and ensures product purity and performance stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 This is a partial structural cross-section of the present invention without the material bin, cryogenic treatment box, bag-type particle collector, air source unit and barrel. Figure 1 ; Figure 3This is a partial structural cross-section of the present invention without the material bin, cryogenic treatment box, bag-type particle collector, air source unit and barrel. Figure 2 ; Figure 4 It is a top view of the target-type airflow mill, the discharge port, the supersonic nozzle, the feed port and the drive motor of the present invention; Figure 5 It is a structural schematic diagram of the grading impeller in the present invention; Figure 6 It is a schematic structural diagram of the tungsten carbide target in the present invention; In the picture: 1. Cryogenic treatment box; 2. Target airflow mill; 3. Crushing chamber; 4. Classifying impeller; 5. Discharge port; 6. Bag-type particle collector; 7. Tungsten carbide target plate; 8. Supersonic nozzle; 9. Air source unit; 10. Feed port; 11. Material bin; 12. Drive motor; 13. Output shaft; 14. Barrel. DETAILED DESCRIPTION

[0021] The present invention is described and illustrated in detail below with reference to the embodiments.

[0022] Example 1 like Figure 1-6 As shown, the PEEK ultrafine grinding system includes a cryogenic treatment box 1, one end of the cryogenic treatment box 1 is connected to a target airflow mill 2, a grinding chamber 3 is provided in the target airflow mill 2, a classifying impeller 4 is provided for rotation inside the grinding chamber 3, and the classifying impeller 4 is provided in a cylindrical shape as a whole. A discharge port 5 is provided at one end of the target airflow mill 2 to cooperate with the classifying impeller 4, and a driving motor 12 is provided at the other end of the target airflow mill 2 to cooperate with the classifying impeller 4. The discharge port 5 is connected to a bag-type particle collector at one end away from the target airflow mill 2. A tungsten carbide target disk 7 is fixedly provided in the crushing chamber 3, a supersonic nozzle 8 is provided on one side of the crushing chamber 3 in conjunction with the tungsten carbide target disk 7, one end of the supersonic nozzle 8 extends into the crushing chamber 3, and the other end of the supersonic nozzle 8 penetrates the target airflow mill 2 and is connected to an air source unit 9, an inert gas is provided inside the air source unit 9, liquid nitrogen is provided inside the cryogenic treatment box 1, a temperature sensor and a controller are provided on the crushing chamber 3, the temperature sensor and the controller are electrically connected to the air source unit 9, and a barrel 14 is provided at the bottom of the bag-type particle collector 6.

[0023] The cryogenic treatment box 1 achieves cryogenic pretreatment through liquid nitrogen, and the gas source unit 9 provides low-temperature inert gas through the supersonic nozzle 8. On the one hand, the temperature of the crushing chamber 3 is maintained at a relatively low temperature to avoid thermal degradation of the PEEK raw material. On the other hand, it drives the PEEK raw material to collide with the tungsten carbide target plate 7 at high speed, so that the PEEK raw material is broken into PEEK particles; the driving motor 12 drives the classifying impeller 4 to rotate at high speed in the crushing chamber 3, realizing efficient preparation and narrow distribution control of PEEK particles.

[0024] The grinding chamber 3 is arranged in a disc shape as a whole, and the classifying impeller 4 is coaxially arranged on the central axis of the grinding chamber 3.

[0025] A feed port 10 is provided on the top of the target airflow mill 2 , and one end of the feed port 10 away from the target airflow mill 2 is connected to the cryogenic treatment box 1 .

[0026] The end of the cryogenic treatment box 1 away from the target airflow mill 2 is connected to the material bin 11. The material bin 11 is connected to the cryogenic treatment box 1 to support batch storage and loading of PEEK raw materials, thereby improving production efficiency.

[0027] An output shaft 13 is provided on the drive motor 12. The end of the output shaft 13, remote from the drive motor 12, passes through the target jet mill 2 and connects to the classifying impeller 4, which is made of titanium alloy. The drive motor 12 directly drives the classifying impeller 4 via the output shaft 13, with an adjustable speed of 5,000-20,000 rpm, ensuring controllable centrifugal force. The classifying impeller 4 is made of titanium alloy, which maintains high strength even in low-temperature environments, offers strong resistance to erosion and wear, and has a long service life.

[0028] The tungsten carbide target disk 7 includes a crushing disk and an assembly connection block. The end face of the crushing disk is tilted to match the supersonic nozzle 8. A shearing edge is provided on the end face of the crushing disk. The shearing edge is serrated as a whole. The hardness of the tungsten carbide target disk 7 is between 2200 and 2300 HV.

[0029] The end face of the crushing disc is tilted in conjunction with the supersonic nozzle 8, which can form an impact angle with the airflow ejected from the supersonic nozzle 8, so that the PEEK raw material particles can more accurately impact the crushing disc under the drive of the airflow, thereby improving the impact crushing efficiency and enhancing the crushing effect of the PEEK raw material; the shear edge on the end face of the crushing disc can increase the contact shear area with the PEEK raw material. Under the synergistic effect of the impact and the airflow impact, the shear force is used to accelerate the crushing process of the PEEK raw material, thereby reducing the crushing time and energy consumption; the high hardness of 2200~2300HV makes the tungsten carbide target disc 7 have extremely strong impact and wear resistance, and can withstand long-term and high-frequency impact and friction of PEEK raw materials, thereby extending the service life of the tungsten carbide target disc 7, reducing the number and cost of maintenance shutdowns due to equipment wear, and ensuring the continuity and stability of the crushing process.

[0030] A heat-insulating layer is provided outside the barrel 14 , and a sealing ring is provided between the discharge port 5 and the target-type airflow mill 2 .

[0031] The pulverization method using the PEEK ultrafine pulverization system comprises the following steps: S1. Material pretreatment The PEEK raw material is conveyed to a cryogenic treatment box 1 and subjected to cryogenic treatment by staged cooling. In the first stage, the temperature is lowered from room temperature to -80-90°C at a rate of 3-5°C / min and kept at this temperature for 10-15 minutes. In the second stage, the temperature is lowered to -150-196°C at a rate of 6-8°C / min and kept at this temperature for 20-40 minutes. After the treatment is completed, the PEEK raw material is conveyed to the grinding chamber 3 in the target airflow mill 2. S2. Initial crushing Turn on the gas source unit 9 to spray the inert gas into the crushing chamber 3 through the supersonic nozzle 8, forming a high-speed airflow with a Mach number of 0.9 to 1.5. The high-speed airflow pushes the PEEK raw material to collide with the tungsten carbide target plate 7, and the PEEK raw material is initially crushed into PEEK particles; S3, Circular Crushing The driving motor 12 is started, and the driving motor 12 drives the classifying impeller 4 to rotate in the crushing chamber 3. The speed of the classifying impeller 4 is controlled to be 5000-20000 rpm to dynamically classify the crushed PEEK particles. During the pulverizing process, inert gas is introduced intermittently. The temperature sensor on the pulverizing chamber 3 monitors the temperature in the pulverizing chamber 3 in real time and transmits the temperature signal to the controller in real time. The controller analyzes and judges after receiving the temperature signal. When the temperature is less than -30°C, the controller sends a stop gas supply instruction to the gas source unit 9, and the gas source unit 9 suspends gas supply; when the temperature is greater than or equal to -30°C, the controller sends a start gas supply instruction to the gas source unit 9, and the gas source unit 9 starts and introduces inert gas until the temperature in the pulverizing chamber 3 drops below -30°C. PEEK ultrafine particles enter the bag-type particle collector 6 through the discharge port 5, and the PEEK coarse particles are thrown back into the crushing chamber 3 to participate in impact crushing again; S4. Finished product collection The crushed PEEK ultrafine particles are enriched in the bag-type particle collector 6. When the amount of PEEK ultrafine particles in the bag-type particle collector 6 reaches 80% of the rated capacity of the bag-type particle collector 6, the PEEK ultrafine particles in the bag-type particle collector 6 are discharged to the bottom barrel 14 to complete the collection of the finished product.

[0032] The PEEK raw material is cooled to -150--196°C in a cryogenic treatment chamber 1, inducing grain boundary cracks within the PEEK raw material. Combined with the shear edges on the surface of the tungsten carbide target 7, this effectively reduces the high toughness of the PEEK raw material, significantly reducing the plastic deformation of the PEEK raw material during the pulverization process, thereby improving pulverization efficiency and reducing energy consumption. A gas source unit 9 introduces low-temperature inert gas into the pulverization chamber 3 via a supersonic nozzle 8, maintaining the temperature of the pulverization chamber 3 below -30°C. This effectively prevents oxidative degradation of the PEEK raw material due to frictional heat generation, thereby ensuring the purity and performance stability of the subsequent PEEK ultrafine particles. A drive motor 12 drives the classifying impeller 4 to rotate at high speed, classifying the PEEK particles in real time through a centrifugal force field. The coarse PEEK particles are returned to the pulverization chamber 3 for recycling, achieving submicron pulverization and a narrow particle size distribution of the PEEK ultrafine particles. A material bin 11, cryogenic treatment chamber 1, target-type airflow mill 2, and bag-type particle collector 6 are sequentially connected to achieve automated connection from raw material pretreatment to finished product collection, supporting large-scale continuous production and shortening the preparation cycle.

[0033] In step S2, the inert gas is nitrogen or argon, and the temperature of the inert gas is between -50°C and -60°C. The low-temperature inert gas is continuously introduced into the pulverization chamber 3 through the supersonic nozzle 8. This not only removes the heat generated by the friction of the PEEK particles, maintaining the low temperature of the pulverization chamber 3, but also isolates the oxygen, preventing oxidative degradation of the PEEK raw material.

[0034] During the unloading process in step S4, nitrogen is continuously introduced into barrel 14 to displace the air. This isolates oxygen, preventing oxidation of the PEEK ultrafine particles due to their large surface area and high activity, thereby ensuring their mechanical properties and chemical stability. It also reduces humidity within barrel 14, preventing the PEEK ultrafine particles from absorbing moisture and agglomerating, ensuring their dispersion and facilitating subsequent processing.

[0035] Example 2 The pulverization method using the PEEK ultrafine pulverization system comprises the following steps: S1. Material pretreatment The PEEK raw material is transported to a cryogenic treatment box 1 and subjected to cryogenic treatment by a staged cooling method. In the first stage, the temperature is lowered from room temperature to -80°C at a rate of 5°C / min and kept at this temperature for 15 minutes. In the second stage, the temperature is lowered to -150°C at a rate of 8°C / min and kept at this temperature for 40 minutes. After the treatment is completed, the PEEK raw material is transported to the grinding chamber 3 in the target airflow mill 2. S2. Initial crushing The gas source unit 9 is turned on to spray the inert gas into the pulverizing chamber 3 through the supersonic nozzle 8, forming a high-speed airflow with a Mach number of 0.9. The high-speed airflow pushes the PEEK raw material to collide with the tungsten carbide target plate 7, and the PEEK raw material is initially pulverized into PEEK particles. The hardness of the tungsten carbide target plate 7 is between 2200 HV. S3, Circular Crushing The driving motor 12 is started, and the driving motor 12 drives the classifying impeller 4 to rotate in the pulverizing chamber 3. The rotation speed of the classifying impeller 4 is controlled at 10000 rpm to dynamically classify the pulverized PEEK particles.

[0036] The rest is the same as Example 1.

[0037] Example 3 The pulverization method using the PEEK ultrafine pulverization system comprises the following steps: S1. Material pretreatment The PEEK raw material is conveyed to a cryogenic treatment box 1 and subjected to cryogenic treatment by a staged cooling method. In the first stage, the temperature is lowered from room temperature to -90°C at a rate of 4°C / min and kept at this temperature for 12 minutes. In the second stage, the temperature is lowered to -196°C at a rate of 6°C / min and kept at this temperature for 20 minutes. After the treatment is completed, the PEEK raw material is conveyed to the grinding chamber 3 in the target airflow mill 2. S2. Initial crushing The gas source unit 9 is turned on to spray the inert gas into the pulverizing chamber 3 through the supersonic nozzle 8, forming a high-speed airflow with a Mach number of 1.2. The high-speed airflow pushes the PEEK raw material to collide with the tungsten carbide target plate 7, and the PEEK raw material is initially pulverized into PEEK particles. The hardness of the tungsten carbide target plate 7 is between 2300 HV. S3, Circular Crushing The driving motor 12 is started, and the driving motor 12 drives the classifying impeller 4 to rotate in the pulverizing chamber 3. The rotation speed of the classifying impeller 4 is controlled at 5000 rpm to dynamically classify the pulverized PEEK particles.

[0038] The rest is the same as Example 1.

[0039] Example 4 The pulverization method using the PEEK ultrafine pulverization system comprises the following steps: S1. Material pretreatment The PEEK raw material is transported to a cryogenic treatment box 1 and subjected to cryogenic treatment by a staged cooling method. In the first stage, the temperature is lowered from room temperature to -85°C at a rate of 3°C / min and kept at this temperature for 10 minutes. In the second stage, the temperature is lowered to -170°C at a rate of 7°C / min and kept at this temperature for 30 minutes. After the treatment is completed, the PEEK raw material is transported to the grinding chamber 3 in the target airflow mill 2. S2. Initial crushing The gas source unit 9 is turned on to spray the inert gas into the grinding chamber 3 through the supersonic nozzle 8, forming a high-speed airflow with a Mach number of 1.5. The high-speed airflow pushes the PEEK raw material to collide with the tungsten carbide target plate 7, and the PEEK raw material is initially crushed into PEEK particles. The hardness of the tungsten carbide target plate 7 is between 2300 HV. S3, Circular Crushing The driving motor 12 is started, and the driving motor 12 drives the classifying impeller 4 to rotate in the pulverizing chamber 3. The rotation speed of the classifying impeller 4 is controlled at 20000 rpm to dynamically classify the pulverized PEEK particles.

[0040] The rest is the same as in Example 1.

[0041] Comparative Example 1 The PEEK raw material was transported to a cryogenic treatment box 1, and subjected to cryogenic treatment, cooling from room temperature to -150°C at a rate of 8°C / min, and kept warm for 40 minutes. After the treatment, the PEEK raw material was transported to the grinding chamber 3 in the target airflow mill 2; the rest was the same as in Example 2.

[0042] Comparative Example 2 The PEEK raw material was transported to a cryogenic treatment box 1, and the PEEK raw material was cryogenically treated, with the temperature dropping from room temperature to -80°C at a rate of 5°C / min and kept warm for 15 minutes. After the treatment, the PEEK raw material was transported to the grinding chamber 3 in the target airflow mill 2; the rest was the same as in Example 2.

[0043] Comparative Example 3 The PEEK raw material was transported to a cryogenic treatment box 1, and subjected to cryogenic treatment, cooling from room temperature to -150°C at a rate of 5°C / min, and kept warm for 15 minutes. After the treatment, the PEEK raw material was transported to the grinding chamber 3 in the target airflow mill 2; the rest was the same as in Example 2.

[0044] Comparative Example 4 The gas source unit 9 is turned on to spray the inert gas into the pulverizing chamber 3 through the supersonic nozzle 8, forming a high-speed airflow with a Mach number of 0.5. The high-speed airflow pushes the PEEK raw material to collide with the tungsten carbide target plate 7, and the PEEK raw material is initially pulverized into PEEK particles. The rest is the same as in Example 2.

[0045] Comparative Example 5 The gas source unit 9 is turned on to spray the inert gas into the pulverizing chamber 3 through the supersonic nozzle 8, forming a high-speed airflow with a Mach number of 2.0. The high-speed airflow pushes the PEEK raw material to collide with the tungsten carbide target plate 7, and the PEEK raw material is initially pulverized into PEEK particles. The rest is the same as in Example 2.

[0046] Comparative Example 6 The driving motor 12 is started, and the driving motor 12 drives the classifying impeller 4 to rotate in the pulverizing chamber 3. The rotation speed of the classifying impeller 4 is controlled at 3000 rpm to dynamically classify the pulverized PEEK particles. The rest is the same as in Example 2.

[0047] Comparative Example 7 The driving motor 12 is started, and the driving motor 12 drives the classifying impeller 4 to rotate in the pulverizing chamber 3. The rotation speed of the classifying impeller 4 is controlled at 30,000 rpm to dynamically classify the pulverized PEEK particles. The rest is the same as in Example 2.

[0048] The PEEK ultrafine particles obtained in Examples 2-4 were compared with the PEEK ultrafine particles obtained by traditional mechanical crushing, and the performance test data are shown in Table 1.

[0049]

[0050] D90: refers to the particle diameter value at which the cumulative mass accounts for 90% in the particle size distribution, representing the upper limit of the size of the larger particles in the powder.

[0051] D10: refers to the particle diameter value that accounts for 10% of the cumulative mass, representing the lower limit of the size of smaller particles in the powder.

[0052] D90 / D10: reflects the uniformity of particle size distribution. The smaller the ratio, the more concentrated the particle size.

[0053] The D90 / D10 of Examples 2-4 are much lower than the D90 / D10 of traditional mechanical grinding, the particle size is more concentrated, and the particle size distribution is narrower; the D90 of Example 2-4 is stable at 7~8μm, while the D90 of traditional mechanical grinding is 16μm, indicating that the PEEK ultrafine particles of Example 2-4 are more fully crushed and the ultrafine grinding effect is significant; the purity of Example 2-4 is stable at 99.9%, while the purity of traditional mechanical grinding is only 95.3%, indicating that the PEEK ultrafine particles of Example 2-4 have low impurity content, which solves the problem of difficult impurity control in traditional PEEK grinding.

[0054] The performance test data of the PEEK ultrafine particles obtained in Comparative Examples 1-7 are shown in Table 2.

[0055]

[0056] As can be seen from Table 2, in terms of particle size distribution uniformity, the D90 / D10 of the PEEK ultrafine particles in Comparative Examples 1-7 is between 1.8 and 2.0, which is lower than the 2.1 of traditional mechanical crushing, but higher than the 1.4 to 1.5 of Examples 2-4. Comparative Example 1 adopts one-step cooling, and does not first slowly cool down to -80~-90℃ for pre-adaptation. The PEEK raw material produces uneven cracks due to the large temperature difference, and the PEEK particles are uneven in size after crushing; Comparative Example 2 only completes the first stage of deep cooling, and does not perform ultra-low temperature deep cooling at -150~-196℃. The toughness of the PEEK raw material is insufficiently reduced, and there are many plastic deformations during crushing. The PEEK particles are unevenly distributed after crushing; Comparative Example 3 skips the first stage of slow cooling and directly cools to -150℃. The PEEK raw material structure is slightly damaged due to sudden cooling, and the PEEK particles are unevenly distributed after crushing; In Comparative Example 4, the inert gas Mach number is 0.5, the airflow impact energy is insufficient, and PEEK The raw material is not fully crushed, and the distribution of PEEK particles becomes wider; in Comparative Example 5, the Mach number of the inert gas is 2.0, the air flow velocity is too fast, some PEEK particles are over-crushed into ultrafine powder, and at the same time, the large PEEK particles are not fully impacted due to the turbulent air flow, and the PEEK particle size distribution becomes wider; in Comparative Example 6, the speed of the grading impeller 4 is 3000rpm, the centrifugal force is insufficient, the PEEK fine particles are difficult to be effectively separated, many PEEK coarse particles remain, and the PEEK particle size distribution becomes wider; in Comparative Example 7, the speed of the grading impeller 4 is 30000rpm, and the speed is too high, which causes the target airflow mill 2 of the equipment to vibrate violently, the air flow is turbulent, the PEEK particles are unevenly classified, and the PEEK particle size distribution becomes wider.

[0057] In terms of pulverization completeness, the D90 of Comparative Examples 1-7 ranged from 13 to 15 μm, which was slightly lower than the 16 μm of traditional mechanical pulverization, but significantly higher than the 7 to 8 μm of Examples 2-4. In Comparative Example 1, the one-step cooling caused uneven embrittlement of the PEEK raw material, resulting in more large PEEK particles remaining during pulverization. In Comparative Example 2, the ultra-low temperature embrittlement was insufficient, making it difficult to completely pulverize large PEEK particles. In Comparative Example 3, the sudden cooling caused uneven internal cracks in the PEEK raw material, resulting in many large PEEK particles remaining after pulverization. In Comparative Example 4, under the propulsion of low-speed airflow, the PEEK raw material had a weak impact on the tungsten carbide target disk 7, making it difficult to pulverize large PEEK particles. In Comparative Example 5, the high-speed airflow pulverized most PEEK particles into finer particles, but the turbulent airflow caused a small amount of large PEEK particles to not effectively impact the tungsten carbide target disk 7. In Comparative Example 6, the low-speed classification made it difficult for large PEEK particles to be thrown back into the pulverization chamber 3, resulting in a large amount of residual PEEK particles. In Comparative Example 7, under high-speed rotation, some PEEK particles were excessively centrifuged to the edge and not effectively pulverized, resulting in a large amount of residual PEEK particles.

[0058] In terms of impurity control, the purity of Comparative Examples 1-4 and Comparative Examples 6-7 ranged from 96.2% to 98.3%. Comparative Example 1 lacked a staged cooling buffer, which damaged the PEEK raw material structure. Comparative Example 2 was cooled only at -80°C, and the deep cooling in Comparative Example 2 only reached -80°C, failing to completely isolate the risk of high-temperature oxidation. Comparative Example 3 lacked a first-stage cooling buffer, which affected the chemical stability of the PEEK raw material. Comparative Example 4 had a low airflow velocity and slow inert gas circulation, resulting in a small amount of oxidation of the PEEK raw material during impact. In Comparative Example 6, the classification speed was too low, causing a large amount of PEEK coarse particles to remain at the edge of the crushing chamber 3, increasing the friction between the PEEK coarse particles and the inner wall of the equipment. Frictional heat generated caused oxidation reactions on the surface of the PEEK coarse particles. In Comparative Example 7, the high-speed rotation of the classification impeller 4 flung the inert gas in the crushing chamber 3 toward the edge, reducing the inert gas's ability to encapsulate the PEEK particles and causing a decrease in the purity of the PEEK ultrafine particles.

Claims

1. A PEEK ultrafine grinding system, comprising a cryogenic treatment box (1), one end of which is connected to a target-type airflow grinder (2), characterized in that: A crushing chamber (3) is provided in the target air flow pulverizer (2), a grading impeller (4) is rotatably provided inside the crushing chamber (3), the grading impeller (4) is cylindrical in shape as a whole, a discharge port (5) is provided at one end of the target air flow pulverizer (2) in conjunction with the grading impeller (4), a driving motor (12) is provided at the other end of the target air flow pulverizer (2) in conjunction with the grading impeller (4), a bag-type particle collector (6) is connected to the discharge port (5) at one end away from the target air flow pulverizer (2), a tungsten carbide target disk (7) is fixedly provided in the crushing chamber (3), and the powder A supersonic nozzle (8) is provided on one side of the crushing chamber (3) in conjunction with a tungsten carbide target plate (7), one end of the supersonic nozzle (8) extends into the crushing chamber (3), and the other end of the supersonic nozzle (8) penetrates the target-type airflow crusher (2) and is connected to an air source unit (9), an inert gas is provided inside the air source unit (9), liquid nitrogen is provided inside the cryogenic treatment box (1), a temperature sensor and a controller are provided on the crushing chamber (3), the temperature sensor and the controller are electrically connected to the air source unit (9), and a barrel (14) is provided at the bottom of the bag-type particle collector (6).

2. The PEEK ultrafine grinding system according to claim 1, characterized in that: The pulverizing chamber (3) is arranged in a disc shape as a whole, and the classifying impeller (4) is coaxially arranged on the central axis of the pulverizing chamber (3).

3. The PEEK ultrafine grinding system according to claim 1, characterized in that: A feed port (10) is provided on the top of the target-type airflow pulverizer (2), and an end of the feed port (10) away from the target-type airflow pulverizer (2) is connected to the cryogenic treatment box (1).

4. The PEEK ultrafine grinding system according to claim 1, characterized in that: One end of the cryogenic treatment box (1) away from the target-type airflow pulverizer (2) is connected to a material bin (11).

5. The PEEK ultrafine grinding system according to claim 1, characterized in that: An output shaft (13) is provided on the driving motor (12), and one end of the output shaft (13) away from the driving motor (12) passes through the target-type airflow pulverizer (2) and is connected to the grading impeller (4), and the grading impeller (4) is made of titanium alloy.

6. The PEEK ultrafine grinding system according to claim 1, characterized in that: The tungsten carbide target disk (7) comprises a crushing disk and an assembly connection block. The end face of the crushing disk is arranged to be tilted in coordination with the supersonic nozzle (8). A shearing edge is arranged on the end face of the crushing disk. The shearing edge is arranged in a serrated shape as a whole. The hardness of the tungsten carbide target disk (7) is between 2200 and 2300 HV.

7. The PEEK ultrafine grinding system according to claim 1, characterized in that: A heat-insulating layer is provided outside the barrel (14), and a sealing ring is provided between the discharge port (5) and the target-type airflow pulverizer (2).

8. A pulverization method using the PEEK ultrafine pulverization system according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Material pretreatment The PEEK raw material is transported to a cryogenic treatment box (1) and subjected to cryogenic treatment by staged cooling. In the first stage, the temperature is lowered from room temperature to -80-90°C at a rate of 3-5°C / min and kept warm for 10-15 minutes. In the second stage, the temperature is lowered to -150--196°C at a rate of 6-8°C / min and kept warm for 20-40 minutes. After the treatment is completed, the PEEK raw material is transported to the grinding chamber (3) in the target airflow mill (2); S2. Initial crushing Turning on the gas source unit (9) to allow the inert gas to be sprayed into the pulverizing chamber (3) through the supersonic nozzle (8), thereby forming a high-speed airflow with a Mach number of 0.9 to 1.

5. The high-speed airflow pushes the PEEK raw material to collide with the tungsten carbide target plate (7), and the PEEK raw material is initially pulverized into PEEK particles; S3, Circular Crushing The driving motor (12) is started, and the driving motor (12) drives the classifying impeller (4) to rotate in the pulverizing chamber (3), and the rotation speed of the classifying impeller (4) is controlled to be 5000-20000 rpm, so as to dynamically classify the pulverized PEEK particles; During the pulverizing process, the inert gas is introduced intermittently. The temperature sensor on the pulverizing chamber (3) monitors the temperature in the pulverizing chamber (3) in real time and transmits the temperature signal to the controller in real time. The controller analyzes and judges after receiving the temperature signal. When the temperature is less than -30°C, the controller sends a stop gas supply instruction to the gas source unit (9), and the gas source unit (9) suspends gas supply. When the temperature is greater than or equal to -30°C, the controller sends a start gas supply instruction to the gas source unit (9), and the gas source unit (9) starts and introduces the inert gas until the temperature in the pulverizing chamber (3) drops below -30°C. The PEEK ultrafine particles enter the bag-type particle collector (6) through the discharge port (5), and the PEEK coarse particles are thrown back into the crushing chamber (3) to participate in impact crushing again; S4. Finished product collection The crushed PEEK ultrafine particles are enriched in the bag-type particle collector (6). When the amount of PEEK ultrafine particles in the bag-type particle collector (6) reaches 80% of the rated capacity of the bag-type particle collector (6), the PEEK ultrafine particles in the bag-type particle collector (6) are discharged to the bottom barrel (14), completing the collection of the finished product.

9. The pulverization method using the PEEK ultrafine pulverization system according to claim 8, characterized in that: In step S2, the inert gas is nitrogen or argon, and the temperature of the inert gas is between -50 and -60°C.

10. The pulverization method using the PEEK ultrafine pulverization system according to claim 8, characterized in that: In step S4, nitrogen is continuously introduced into the barrel (14) to replace the air during the unloading process.

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