A fan frame plastic package magnet cooling fan and its preparation process

Abstract

The application relates to the field of heat dissipation fan processing, and particularly discloses a heat dissipation fan with a fan frame plastic-coated magnetically charged magnet and a preparation process thereof. The heat dissipation fan with the fan frame plastic-coated magnetically charged magnet comprises a fan outer frame, the bottom of the fan outer frame is provided with a bearing mounting seat, the bottom of the bearing mounting seat is upwardly extended and provided with a mounting channel, a magnet is mounted on the bottom of the bearing mounting seat corresponding to the mounting channel, the bearing mounting seat and the fan outer frame are made of plastic material, and the magnet, the bearing mounting seat and the fan outer frame are integrally plastic-coated and formed; a magnetically conductive shaft core is mounted in the mounting channel, the bottom of the magnetically conductive shaft core is oppositely arranged with the magnet, so that magnetic attraction is generated between the magnetically conductive shaft core and the magnet. The preparation process comprises the following steps: magnetically charging the magnet, integrally plastic-coating the magnetically charged magnet and plastic material to form, and assembling. The preparation process is simple, cost is saved, the heat dissipation fan is assembled, a working procedure is saved, the heat dissipation fan has good heat dissipation stability, and is suitable for small-size and light-thin heat dissipation fan products.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of heat dissipation fan processing, and more particularly to a heat dissipation fan with a fan frame plastic-encased magnetically charged magnet and a preparation process thereof. BACKGROUND

[0002] The heat dissipation fan generally comprises a fan shell, a magnetically conductive shaft core, a hydraulic bearing structure, a motor assembly and fan blades. The use of the hydraulic bearing structure improves the design of the bottom of the traditional oil-containing bearing which is not sealed, and seals the bottom of the bearing completely, thereby having the advantages of longer service life and lower noise. The hydraulic bearing structure adopts a ring-back type oil locking structure, thereby reducing the oil leakage problem and prolonging the service life of the heat dissipation fan.

[0003] However, under the condition of long-term high-speed operation of the heat dissipation fan, the magnetic attraction between the stator and the rotor in the motor assembly is prone to be insufficient, thereby reducing the long-term use stability of the heat dissipation fan. In order to solve this problem, the prior art installs a magnetically conductive metal shell at the bottom of the bearing seat of the fan shell, and places a magnet in the magnetically conductive metal shell, so as to enhance the magnetic attraction between the stator and the rotor by means of the magnetic attraction of the magnet to the magnetically conductive shaft core.

[0004] Although the above-mentioned solution can enhance the magnetic attraction between the stator and the rotor, the installation process of the entire magnetically conductive metal shell and the magnet is relatively complicated, the processing cost is relatively high, and the installation of the magnetically conductive metal shell occupies a lot of space. For the heat dissipation fan with small volume and thin thickness, the assembly is difficult and the applicability is low. SUMMARY

[0005] In order to solve the problems of complicated installation process and high processing cost of the heat dissipation fan, the present application provides a heat dissipation fan with a fan frame plastic-encased magnetically charged magnet and a preparation process thereof.

[0006] In the first aspect, the present application provides a heat dissipation fan with a fan frame plastic-encased magnetically charged magnet, which adopts the following technical solution: a heat dissipation fan with a fan frame plastic-encased magnetically charged magnet, comprising a fan outer frame, a bearing mounting seat is arranged at the bottom of the fan outer frame, an installation channel is arranged upwardly at the bottom of the bearing mounting seat, a magnet is mounted at the bottom of the bearing mounting seat corresponding to the installation channel, the bearing mounting seat and the fan outer frame are made of plastic material, and the magnet, the bearing mounting seat and the fan outer frame are integrally plastic-encased; a magnetically conductive shaft core is mounted in the installation channel, the bottom of the magnetically conductive shaft core is arranged opposite to the magnet, so that the magnetic attraction is generated between the magnetically conductive shaft core and the magnet.

[0007] By adopting the technical scheme, the fan outer frame, the bearing mounting seat and the magnet of the heat dissipation fan are integrally plastic molded, the plastic material is used as the shell, the heat dissipation fan has the advantages of light weight and easy molding, the fan shell is made, the installation space and the installation cost are saved, and the heat dissipation fan is more suitable for small size and thin heat dissipation fan; the magnetic attraction force between the magnet and the magnetically conductive shaft core is stable, the running stability and the heat dissipation efficiency of the heat dissipation fan during long-term use are improved, and the heat dissipation fan can be applied to high-speed and high-heat dissipation performance direct current axial flow fan and the like.

[0008] Preferably, the magnet is any one of a samarium-cobalt magnet and an aluminum-nickel-cobalt magnet.

[0009] By adopting the technical scheme, the magnet has stable magnetic field strength and high working temperature, and the magnet is not prone to magnetic reduction during processing and use.

[0010] Preferably, the thickness of the magnet is 1-5mm.

[0011] By adopting the technical scheme, the magnet with the optimal thickness can save the installation space and has moderate magnetism, can stably attract the magnetically conductive shaft core, and improve the running stability of the heat dissipation fan, and is suitable for small size and thin heat dissipation fan, and the thickness of the magnet can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm or 5mm.

[0012] In a second aspect, the application provides a preparation process of a heat dissipation fan with a fan frame plastic-molded magnetized magnet, which adopts the following technical scheme:

[0013] A preparation process of a heat dissipation fan with a fan frame plastic-molded magnetized magnet, comprising the following steps: S1, magnetizing the magnet to obtain a magnetized magnet;

[0014] S2, placing the magnetized magnet into an injection mold, melting and injection molding plastic material into the injection mold, pressure maintaining and cooling forming to obtain an integrally plastic-molded fan frame;

[0015] S3, assembling the integrally plastic-molded fan frame, the magnetically conductive shaft core and other parts to obtain the heat dissipation fan.

[0016] By adopting the technical scheme, the magnet is first magnetized to have saturated magnetism, then the magnetized magnet is put into the injection mold to be integrally molded with the plastic material, so that the plastic material covers the magnet, then pressure maintaining and cooling forming are performed to prepare the integrally plastic-molded fan frame, and finally assembly is performed to prepare the cooling fan of the application. The preparation process of the application saves the process of installing the magnetically conductive metal shell and the magnet on the fan outer frame, saves space and production cost and production process, improves the assembly efficiency of the cooling fan, and the cooling fan prepared by the process is more lightweight, and the magnetism of the magnet is not affected.

[0017] Preferably, the magnetization voltage in the S1 step is 3000-4000V, the capacitance is 5000-10000F, and the magnetization time is 1-2s.

[0018] By adopting the technical scheme, the optimal magnetization condition can improve the magnetization efficiency of the magnet, so that the magnet has saturated magnetism.

[0019] Preferably, the mold temperature for the mold injection in the S2 step is 20-70℃, and the mold injection time is 5-10s.

[0020] By adopting the technical scheme, the optimal mold injection mold temperature and mold injection time can enable the plastic material to be stably injected into the injection mold, reduce the problem of poor injection, and improve the injection efficiency.

[0021] Preferably, the pressure maintaining pressure in the S2 step is 40-50MPa, and the pressure maintaining time is 15-40s.

[0022] By adopting the technical scheme, the optimal pressure maintaining pressure and pressure maintaining time can enable the plastic material injected into the injection mold to be fully filled, reduce the problems of shrinkage and porosity, and improve the compactness and quality of the integrally plastic-molded fan frame.

[0023] Preferably, the mold injection of the plastic material in the S2 step is divided into four stages: the first stage: the injection rate is 55-75%, and the injection pressure is 35-45MPa; the second stage: the injection rate is 30-50%, and the injection pressure is 25-35MPa; the third stage: the injection rate is 15-25%, and the injection pressure is 5-10MPa; the fourth stage: the injection rate is 30-35%, and the injection pressure is 60-120MPa.

[0024] By adopting the above technical scheme, the rate and pressure of the mold injection are controlled more optimally, the moderate injection pressure is controlled in the first stage, high-speed injection is used, the moderate injection pressure is controlled in the second stage, low-speed injection is used, the lower injection rate is controlled in the third stage, low-pressure injection is used, the moderate injection rate is controlled in the fourth stage, high-pressure injection is used, and through the cooperation of the four stages, the plastic material can overcome the resistance of the cavity of the injection mold while uniformly covering the magnet, and is uniformly and fully filled in the injection mold, thereby improving the stability of injection and reducing the occurrence of shrinkage, unevenness and the like.

[0025] Preferably, the plastic material in the S2 step is any one or combination of PBT, PC, ABS, PPE, PA, PPS, PET, PP, PS.

[0026] By adopting the above technical scheme, the above plastic material is used as the material of the integrally plastic-molded fan frame, has good mechanical properties and good processing forming property, is light in quality, good in quality, and suitable for small-size and light-thin heat dissipation fans.

[0027] Preferably, the S1 step and the S2 step further comprise a pretreatment step of magnetized magnets, the pretreatment agent is used to soak the magnetized magnets in the pretreatment step, and drying is performed.

[0028] By adopting the above technical scheme, the pretreatment agent is used to pretreat the magnetized magnets, so as to improve the combination stability of the magnetized magnets and the plastic material in the injection process, and further improve the magnetic attraction between the integrally plastic-molded fan frame and the magnetically conductive shaft core, and further improve the long-term heat dissipation stability of the heat dissipation fan.

[0029] Preferably, the soaking time is 3-8 min, and the soaking temperature is 40-50 DEG C.

[0030] By adopting the above technical scheme, the optimal soaking condition can make the pretreatment agent fully soak the surface of the magnetized magnets, and improve the pretreatment efficiency of the magnetized magnets.

[0031] Preferably, the pretreatment agent is prepared from the following raw materials by weight:

[0032] Carbonyl iron powder 20-30 parts

[0033] Silane coupling agent 2-4 parts

[0034] Epoxy silicone resin 35-55 parts

[0035] Pentaerythritol triallyl ether 3-6 parts

[0036] Solvent 5-10 parts

[0037] Amino-terminated polyether 1-2 parts.

[0038] By adopting the technical scheme, the epoxy silicone resin is used as a film-forming matrix, and the synergistic effect of the silane coupling agent and the pentaerythritol triallyl ether enables the carbonyl iron powder to be uniformly dispersed in the molecular chain segment interweaving system of the silane coupling agent, the pentaerythritol triallyl ether and the epoxy silicone resin, and under the curing effect of the terminal amino polyether, the magnetic attraction between the carbonyl iron powder and the magnetized magnet is generated, in the process of immersion pretreatment, the pretreatment agent forms a uniform and dense film on the surface of the magnetized magnet, and in the process of plastic melt injection molding, the combination stability of the magnetized magnet and the plastic material is improved, and the problems of shrinkage and unevenness of the integrally plastic-molded fan frame are solved.

[0039] Preferably, the silane coupling agent is composed of octavinylsilsesquioxane and 3-isocyanate propyl trimethoxysilane at a weight ratio of 1:(1-2).

[0040] By adopting the above technical scheme, the above-mentioned optimal amount ratio of octavinylsilsesquioxane and 3-isocyanate propyl trimethoxysilane has a good synergistic effect, which can improve the uniformity of the dispersion of the carbonyl iron powder, and interweave with the molecular chain segments of the pentaerythritol triallyl ether and the epoxy silicone resin, thereby improving the adhesion stability of the film and the combination stability of the magnetized magnet and the plastic material.

[0041] In summary, the present application has the following advantages:

[0042] 1. The heat dissipation fan of the present application integrally plastic-molds the fan outer frame, bearing mounting seat and magnet to form an integrally plastic-molded outer frame, thereby saving installation space and installation cost, and being more suitable for small-size and thin heat dissipation fans. Compared with the prior art, the heat dissipation fan of the present application generates a continuous and stable magnetic attraction force between the magnetically conductive shaft core and the magnet, thereby improving the operation stability and heat dissipation efficiency of the heat dissipation fan during long-term use.

[0043] 2. The preparation process of the heat dissipation fan of the present application magnetizes the magnet first, then injection-molds the magnet together with the plastic material, and finally assembles, thereby saving the process of installing the magnetically conductive metal shell and the magnet in the fan outer frame, saving space and production cost and process, improving the assembly efficiency of the heat dissipation fan, and the heat dissipation fan made in this way is more lightweight, without affecting the magnetism of the magnet.

[0044] 3. After magnetizing the magnet, the present application uses a pretreatment agent composed of carbonyl iron powder, silane coupling agent, epoxy silicone resin, pentaerythritol triallyl ether and terminal amino polyether to pretreat the magnetized magnet, thereby improving the combination stability of the magnet and the plastic material during integrally plastic-molding, reducing the problems of shrinkage and unevenness, and further improving the heat dissipation stability and efficiency of the heat dissipation fan. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 Fig. 1 is a cross-sectional view of a fan frame of a fan frame plastic-encased magnet magnet with a fan.

[0046] BRIEF DESCRIPTION OF DRAWINGS: 1, fan frame; 2, bearing mounting seat; 21, mounting channel; 3, bearing; 4, magnet; 5, magnetically conductive shaft core; 6, rotor; 7, stator; 8, fan blade. DETAILED DESCRIPTION

[0047] The application will be further described in detail below in conjunction with the accompanying drawings and examples. Figure 1 and examples.

[0048] The following are the sources and specifications of some of the raw materials of the application. The raw materials used in the preparation examples and examples of the application can be obtained commercially, including but not limited to the following types and manufacturers of raw materials. Raw materials with equivalent performance can also be used:

[0049] 1. Carbonyl iron powder: 1-3 μm, content greater than 99%;

[0050] 2. Epoxy silicone resin: Sihai, SH023, solid content 50%, epoxy content 0.02-0.07;

[0051] 3. Pentaerythritol triallyl ether: CAS number 1471-17-6, content 99%;

[0052] 4. Amino-terminated polyether: polyetheramine D230;

[0053] 5. Octavinylsilsesquioxane: Fushiman, content 97%;

[0054] 6. 3-isocyanate propyl trimethoxysilane: Kemira, CAS number 15396-00-6, content 98%.

[0055] Preparation example of pretreatment agent

[0056] Preparation example 1

[0057] Preparation example 1 discloses a pretreatment agent prepared by the following steps:

[0058] 3.5 kg of epoxy silicone resin, 0.3 kg of pentaerythritol triallyl ether, 0.2 kg of vinyl trimethoxysilane as silane coupling agent, and 2 kg of carbonyl iron powder were added to a mixer, mixed uniformly, 0.5 kg of ethyl acetate was added as a solvent, and 0.1 kg of amino-terminated polyether was added, stirred uniformly, and a pretreatment agent was prepared.

[0059] Preparation examples 2-3

[0060] Preparation Example 2-3 is different from Preparation Example 1 in that the raw material usage is different, as shown in Table 1 below.

[0061] Table 1 Raw material usage of Preparation Examples 1-3

[0062]

[0063]

[0064] Preparation Example 4

[0065] Preparation Example 4 is different from Preparation Example 1 in that the silane coupling agent is composed of octa-vinyl silsesquioxane and 3-isocyanate propyl trimethoxy silane, the usage of octa-vinyl silsesquioxane is 0.1 kg, the usage of 3-isocyanate propyl trimethoxy silane is 0.1 kg, and the others are the same as Preparation Example 1.

[0066] Preparation Example 5

[0067] Preparation Example 5 is different from Preparation Example 4 in that the usage of octa-vinyl silsesquioxane is 0.067 kg, the usage of 3-isocyanate propyl trimethoxy silane is 0.133 kg, and the others are the same as Preparation Example 4.

[0068] Preparation Example 6

[0069] Preparation Liu 6 is different from Preparation Example 1 in that the pentaerythritol triallyl ether is replaced by glycidyl methacrylate in equal amount, and the others are the same as Preparation Example 1.

[0070] Example

[0071] Example 1

[0072] Example 1 discloses a heat dissipation fan of a fan frame plastic-encased magnetically charged magnet, referring to Figure 1, including the fan outer frame 1, the bottom of the fan outer frame 1 is provided with a bearing mounting seat 2, the bottom of the bearing mounting seat 2 is provided with an installation channel 21 extending upward in the middle, the installation channel 21 is provided with a magnet 4 corresponding to the bottom of the bearing seat 2, the thickness of the magnet 4 is 1-5mm, preferably 1-2mm in the embodiment, the fan outer frame 1 and the bearing mounting seat 2 are both made of plastic material, preferably, the plastic material can be one of PBT, PC, ABS, PPE, PA, PPS, PET, PP, PS or a mixture of two or three, the fan outer frame 1 and the bearing mounting seat 2 in the embodiment are both made of PBT material; the magnet can be a samarium-cobalt magnet or an aluminum-nickel-cobalt magnet, a samarium-cobalt magnet is used in the embodiment, which has high working temperature and stability; the thickness of the magnet is 1-2mm, the thickness of the magnet in the embodiment is 1.5mm, which has good lightness and thinness while having good magnetic attraction; the fan outer frame 1, the bearing mounting seat 2 and the magnet 4 are integrally molded by plastic molding to form an integrally molded fan frame, so that the magnet 4, the fan outer frame 1 and the bearing mounting seat 3 are fixedly connected; a magnetically conductive shaft core 5 is installed in the installation channel 21, the magnetically conductive shaft core 5 is arranged above the magnet 4 and is oppositely arranged, the magnetically conductive shaft core 5 and the magnet 4 generate magnetic attraction, so that the bottom of the magnetically conductive shaft core 5 is magnetically connected with the magnet 4, and the two ends of the magnetically conductive shaft core 5 are connected with the fan blades 8; the magnetically conductive shaft core 5 is connected with a bearing 3 on the outside, the bearing 3 is provided with a stator 7 and a rotor 6 corresponding to the outside of the installation channel 21, the rotor 6 is connected to the inner side of the fan blades 8 and is arranged around the outside of the stator 7, and a coil is wound on the stator 7, when the coil is energized, based on the principle of electromagnetic induction, the rotor 6 drives the fan blades 8 to rotate around the magnetically conductive shaft core 5, under the stable magnetic attraction of the magnet 4 and the magnetically conductive shaft core 5, the heat dissipation fan can stably and continuously dissipate heat, the operating principle of the heat dissipation fan is known in the art, therefore, it will not be described here; the heat dissipation fan of the application uses an integrally molded fan frame as the shell structure of the heat dissipation fan, which saves space, the magnetic attraction between the magnet 4 and the magnetically conductive shaft core 5 is stable, the heat dissipation efficiency of the prepared fan is high, and the heat dissipation performance is stable; the integrally molded fan frame makes the heat dissipation fan small in size and light in weight, which has good applicability and practicality.

[0073] Embodiment 2

[0074] Embodiment 2 discloses a preparation process of a fan frame plastic molding magnetized magnet heat dissipation fan, comprising the following steps:

[0075] The application takes the preparation of a direct current axial flow fan with a size of 60x60x20mm as an example:

[0076] S1, use a magnetizing machine to magnetize a samarium-cobalt magnet with a thickness of 1.5mm, control the magnetizing voltage to be 3000V, the capacitance to be 5000μF, and the magnetizing time to be 2s, and obtain a magnetized magnet;

[0077] S2, adjust the temperature of the injection mold of the injection molding machine to 20°C, the mold injection time is 5s, put the magnetized magnet into the injection mold of the injection molding machine; control the rotating speed of the extruder to 50r / min, use the extruder to melt and inject PBT plastic material into the injection mold under the condition of temperature 240°C, the melting temperature is adjusted according to the material quality of different plastic materials, the commonly used plastic materials can also be one of PC, ABS, PPE, PA, PPS, PET, PP, PS and the like or two mixed or three mixed, set the injection amount of plastic material according to the size requirement of the prepared product, control the injection rate and injection pressure of the plastic material in four stages, as follows: the injection rate of the first stage is 55%, the injection pressure is 35MPa, and the injection amount of the plastic material accounts for 40% of the total weight of the plastic material; the injection rate of the second stage is 30%, the injection pressure is 25MPa, and the injection amount of the plastic material accounts for 30% of the total weight of the plastic material; the injection rate of the third stage is 15%, the injection pressure is 5MPa, and the injection amount of the plastic material accounts for 20% of the total weight of the plastic material; the injection rate of the fourth stage is 30%, the injection pressure is 60MPa, and the injection amount of the remaining 10% of the plastic material, after injection is completed, the pressure is kept at 40MPa for 15s, and then cooled at a temperature of 20°C for 15s, demolding, and obtaining an integrated plastic molded fan frame;

[0078] S3, assemble the integrated plastic molded fan frame, the magnetic shaft core 5 and other parts, the other parts including the bearing 3, the rotor 6, the stator 7, the fan blade 8 and the like, for details, please refer to Figure 1 , the above-mentioned parts are all structures of heat dissipation fans known in the art, which will not be described here in detail, to obtain a heat dissipation fan.

[0079] Example 3-4

[0080] The difference between example 3-4 and example 2 is that the preparation process parameters are different, for details, please refer to the following table 2.

[0081] Table 2 preparation process parameters table of examples 2-4

[0082]

[0083]

[0084] Example 5

[0085] Example 5 differs from Example 2 in that the injection rate of the first stage is 15%, the injection pressure is 35 MPa, and 40% of the total weight of the plastic material is injected; the injection rate of the second stage is 30%, the injection pressure is 25 MPa, and 30% of the total weight of the plastic material is injected; the injection rate of the third stage is 30%, the injection pressure is 5 MPa, and 20% of the total weight of the plastic material is injected; the injection rate of the fourth stage is 55%, the injection pressure is 60 MPa, and the remaining 10% of the plastic material is injected, and the other conditions are the same as in Example 2.

[0086] Example 6

[0087] Example 6 differs from Example 2 in that the injection rate of the first stage is 55%, the injection pressure is 60 MPa, and 40% of the total weight of the plastic material is injected; the injection rate of the second stage is 30%, the injection pressure is 35 MPa, and 30% of the total weight of the plastic material is injected; the injection rate of the third stage is 15%, the injection pressure is 25 MPa, and 20% of the total weight of the plastic material is injected; the injection rate of the fourth stage is 30%, the injection pressure is 5 MPa, and the remaining plastic material is injected, and the other conditions are the same as in Example 5.

[0088] Example 7

[0089] Example 7 differs from Example 2 in that a pre-treatment step of the magnetizing magnet is further included between the S1 step and the S2 step. In the pre-treatment step, a pre-treatment agent is used to soak the magnetizing magnet prepared in the S1 step, the soaking time is 3 min, the soaking temperature is 40°C, and after soaking, the magnet is dried at a temperature of 100°C for 20 min, and then the S2 step is performed. The pre-treatment agent is a commercially available pre-treatment agent, which is composed of 30% epoxy resin, 69% ethyl acetate, and 1% polyetheramine D230. The epoxy resin is E44 epoxy resin with an epoxy equivalent weight of 210-230. The other conditions are the same as in Example 2.

[0090] Examples 8-13

[0091] Examples 8-13 differ from Example 7 in that the sources of the pre-treatment agents are different, and the conditions of the pre-treatment are also different. See Table 3 below for details.

[0092] Table 3 Sources and condition parameters of pre-treatment agents for Examples 8-13

[0093]

[0094] Comparative Example 1

[0095] Comparative Example 1 discloses a heat dissipation fan, which is different from Example 1 in that a magnetically conductive metal shell is fixedly installed at the bottom of the fan frame, specifically, the magnetically conductive metal shell is selected to be an iron material metal shell, and the magnetized magnet is placed in the magnetically conductive metal shell, and the rest is the same as Example 1.

[0096] Performance detection test

[0097] 1. Appearance test of the integrally plastic-molded fan frame prepared in Examples 2-13 was performed: the shrinkage hole of the magnet plastic-molding position of the integrally plastic-molded fan frame was observed, the flatness was observed, and the observation results were recorded.

[0098] The following are the appearance test data of the integrally plastic-molded fan frame prepared in Examples 2-13, which are specifically shown in Table 4 below.

[0099] Table 4 Appearance test data of the integrally plastic-molded fan frame of Examples 2-13

[0100]

[0101] It can be seen from Examples 2-6 and Table 4 that controlling the optimal injection molding speed and injection molding pressure can reduce the shrinkage of the magnet position of the integrally plastic-molded fan frame prepared. In Example 5, the injection molding speed is changed, first using low speed and then using high speed, and the shrinkage of the magnet position of the integrally plastic-molded fan frame prepared is obviously increased. It may be because the plastic material contacts the magnet and the injection molding mold and cools quickly, thereby causing local shrinkage and further shrinkage hole. In Example 6, the injection molding pressure is changed, first using high pressure and then using low pressure, and the shrinkage of the magnet position of the integrally plastic-molded fan frame prepared is obviously increased. It may be because the injection molding pressure is insufficient in the later stage of injection molding, so that the plastic material cannot be uniformly filled into the injection molding mold, and local shrinkage and unevenness occur.

[0102] It can be seen from Examples 2 and 7-13 and Table 4 that the surface flatness of the integrally plastic-molded fan frame prepared by pretreating the magnetized magnet with the pretreatment agent of the application is obviously improved, and there is no shrinkage phenomenon on the surface. Compared with Examples 8-10 and Example 13, the surface flatness of the integrally plastic-molded fan frame prepared by treating the carbonyl iron powder with the optimal amount ratio of silane coupling agent and pentaerythritol triallyl ether in Examples 11-12 is obviously improved. It may be because the optimal amount ratio of silane coupling agent and pentaerythritol triallyl ether produces a good synergistic effect, which improves the dispersibility of the carbonyl iron powder in the pretreatment agent, forms a uniform film on the surface of the magnetized magnet, improves the uniformity and stability of the combination of the magnetized magnet and the plastic material, and further improves the flatness of the integrally plastic-molded fan frame and reduces the shrinkage.

[0103] Compared with the prior art, the preparation process of the application saves the processes of installing the magnetically conductive metal shell and installing the magnet outside the fan frame, saves space, production cost and production process, and the heat dissipation fan prepared in this way is more lightweight, without affecting the magnetism of the magnet, and improves the heat dissipation efficiency and stability of the heat dissipation fan.

[0104] 2. The reliability test of the heat dissipation fans of Example 2, Example 8 and Comparative Example 1 is as follows:

[0105] 1) Noise test of heat dissipation fan

[0106] Place the heat dissipation fan in the soundproof room, set the rotating speed to 4000 r / min, place one meter away from the heat dissipation fan, and align the air inlet of the fan along the direction of the fan rotating shaft, use the A-weighted measurement method, test and record the noise of the heat dissipation fan (unit: dB), and test and record the test results;

[0107] 2) Vibration test

[0108] Set the rotating speed to 4000 r / min, run the heat dissipation fan for 3h, use the dynamic balance tester to test the vibration amplitude of the heat dissipation fan (unit: mm), less than 0.2mm is qualified, test and record the test results;

[0109] The performance test data of the heat dissipation fans of Example 2, Example 8 and Comparative Example 1 are as follows, see Table 5 below.

[0110] Table 5 Performance data table of heat dissipation fans of Example 2, Example 8 and Comparative Example 1

[0111]

[0112] It can be seen from Example 2 and Comparative Example 1 and Table 5 that the heat dissipation fan of the application has smaller noise, lower vibration amplitude and better heat dissipation stability; from Example 2 and Example 8 and Table 5, it can be seen that the heat dissipation stability of the heat dissipation fan can be further improved and the noise can be reduced after the magnet is treated with the pretreatment agent of the application; compared with the prior art, the heat dissipation fan of the application can generate continuous and stable magnetic attraction force, can improve the running stability and heat dissipation efficiency of the heat dissipation fan in the long-term use process, and can be applied to high-speed and high-heat dissipation performance direct-current axial flow fan and the like.

[0113] The specific embodiments are only an explanation of the application, and are not a limitation of the application, and those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, but as long as it is within the scope of the claims of the application, it is protected by the patent law.

Claims

1. A manufacturing process for a cooling fan with a plastic-coated and magnetized fan frame, characterized in that, Includes the following steps: S1. Magnetize the magnet to obtain a magnetized magnet; S2. Place the magnetized magnet into the injection mold, melt the plastic material and mold it into the injection mold, hold the pressure and cool to form a one-piece plastic-coated fan frame; S3. Assemble the one-piece plastic-coated fan frame, magnetic shaft core and other components to obtain a cooling fan; In step S1, the magnetization voltage is 3000-4000V, the capacitance is 5000-10000µF, and the magnetization time is 1-2s. The mold temperature for compression molding in step S2 is 20-70℃, and the compression molding time is 5-10s. The holding pressure in step S2 is 40-50 MPa, and the holding time is 15-40 s; In step S2, the compression molding of the plastic material is divided into four stages: Stage 1: Injection rate of 55-75%, injection pressure of 35-45 MPa; Stage 2: Injection rate of 30-50%, injection pressure of 25-35 MPa; Stage 3: Injection rate of 15-25%, injection pressure of 5-10 MPa; Stage 4: Injection rate of 30-35%, injection pressure of 60-120 MPa. The cooling fan includes a fan frame, a bearing mounting base at the bottom of the fan frame, and an mounting channel extending upward from the bottom of the bearing mounting base. A magnet is mounted on the mounting channel corresponding to the bottom of the bearing mounting base. Both the bearing mounting base and the fan frame are made of plastic, and the magnet, the bearing mounting base, and the fan frame are integrally molded with plastic. A magnetically conductive shaft is installed in the mounting channel, and the bottom of the magnetically conductive shaft is positioned opposite to the magnet, so that a magnetic attraction force is generated between the magnetically conductive shaft and the magnet.

2. The manufacturing process of a cooling fan with a plastic-coated and magnetized fan frame according to claim 1, characterized in that, The magnet is either a samarium cobalt magnet or an alnico magnet.

3. The manufacturing process of a cooling fan with a plastic-coated and magnetized fan frame according to claim 2, characterized in that, The thickness of the magnet is 1-5mm.

4. The manufacturing process of a cooling fan with a plastic-coated and magnetized fan frame according to claim 1, characterized in that, The plastic material in step S2 is any one or a combination of PBT, PC, ABS, PPE, PA, PPS, PET, PP, and PS.

5. The manufacturing process of a cooling fan with a plastic-coated and magnetized fan frame according to claim 1, characterized in that, Between steps S1 and S2, there is a pretreatment step for magnetizing the magnet, in which the magnetizing magnet is immersed in a pretreatment agent and then dried.

Images