A fan volute and a method of manufacturing the same

Abstract

The application relates to the technical field of composite materials. The application discloses a fan volute and a preparation method thereof. The fan volute comprises composite fibers with a skin layer of CoPET covering a core layer of PET; wherein the CoPET comprises polyvinylpyrrolidone and PET. The preparation method comprises the following steps: S1, sending the melted CoPET and PET into a composite spinning box, spinning the CoPET and PET through a spinning assembly to prepare the composite fibers with the skin layer of CoPET covering the core layer of PET; S2, preparing a moldable non-woven fabric through laying and needling; S3, dragging the non-woven fabric to a mold through a track, and performing hot mold molding by using a press and a heatable mold to prepare a rough product; S4, taking out the rough product from the mold by using a mechanical arm and transferring the rough product to a punching mold; S5, punching by using the press and the punching mold, and preparing the fan volute after the punching is completed. The fan volute prepared by the application is light in weight, low in cost and good in sound reduction effect.

Description

Technical Field

[0001] This application relates to the field of composite materials technology, and in particular to a wind turbine volute and its preparation method. Background Technology

[0002] The volute casing of a centrifugal fan is an important component. It is located inside the fan casing and its main function is to collect the gas thrown out from the impeller and guide it into the exhaust port.

[0003] Traditional wind turbine casing materials mainly include aluminum alloy, steel, and galvanized sheet. Aluminum alloy and steel have high strength and corrosion resistance, meeting the requirements of most wind turbine casings. However, their manufacturing cost is relatively high, and their weight is significant, making installation and maintenance difficult. Galvanized sheet is a common wind turbine casing material, offering advantages such as aesthetics, low cost, and ease of processing. It also boasts good corrosion resistance and durability, allowing use in some corrosive environments. However, special care must be taken during the installation and maintenance of galvanized sheet to avoid scratching or damaging the surface during transportation or installation. Furthermore, wind turbine casings made of these metals have good sound wave conductivity, meaning that noise generated during wind turbine operation can be transmitted through the casing, severely disrupting people's normal lives and rest. Prolonged exposure to such an environment may cause fatigue and discomfort, affecting work efficiency and quality of life. Wind turbine noise can also affect hearing. Long-term exposure to excessive noise can lead to hearing loss or noise-induced deafness.

[0004] In existing technologies, the main materials used for novel wind turbine casings are composite materials. Composite materials have advantages such as light weight, corrosion resistance, and low cost, which can reduce manufacturing and transportation costs and improve efficiency. However, these materials have poor damping performance, and vibrations and noise generated during wind turbine operation may more easily propagate within the casing made of these materials, thus causing noise pollution.

[0005] Therefore, there is an urgent need to develop a fan volute that is durable, lightweight, low-cost, and has good noise reduction effect. Summary of the Invention

[0006] In order to solve at least one of the above-mentioned technical problems and to develop a fan volute that is durable, lightweight, low-cost and has good noise reduction effect, this application provides a fan volute and a method for preparing the same.

[0007] On the one hand, the fan casing provided in this application is made of moldable nonwoven fabric, wherein the moldable nonwoven fabric comprises bicomponent continuous PET fiber, and the bicomponent continuous PET fiber is a composite fiber in which the outer layer CoPET is coated with the core layer PET.

[0008] The CoPET comprises polyvinylpyrrolidone and PET, wherein the content of polyvinylpyrrolidone in the CoPET is 1-20 wt%.

[0009] By adopting the above technical solution, this application uses specific raw materials and proportions to produce a fan volute that is durable, lightweight, and has good noise reduction effect. The use of composite fibers with a CoPET outer layer covering a PET core layer increases the strength and durability of the fan volute while reducing its weight.

[0010] CoPET, prepared by modifying PET with polyvinylpyrrolidone (PVP), exhibits excellent sound-absorbing properties and increased flexibility, thereby improving the strength and durability of the fan casing and extending its service life. PPVP-modified PET also offers advantages such as lightweight and low cost. Furthermore, both PPVP and PET are recyclable, making them environmentally friendly materials that align with current green and environmentally friendly development trends.

[0011] Optionally, the CoPET content in the composite fiber is 5-30 wt%.

[0012] Optionally, the CoPET content in the composite fiber is 10-15 wt%.

[0013] By adopting the above technical solution, this application uses a specific CoPET content to produce a fan volute that is superior in all aspects.

[0014] Optionally, the CoPET has a melting point of 190–210°C, and the core PET has a melting point of 260–270°C.

[0015] By adopting the above technical solution, controlling the melting points of the outer layer CoPET and the core layer PET can improve the high-temperature resistance of the fan casing, enabling it to maintain good structural stability at high temperatures, thereby improving the durability of the fan casing. It can also enhance the processing performance of the material.

[0016] Optionally, the degree of polymerization of the polyvinylpyrrolidone is 10. 5 ~10 6 .

[0017] By adopting the above technical solution, this application uses polyvinylpyrrolidone with a specific degree of polymerization to obtain a fan volute with good noise reduction effect and processing performance. When the degree of polymerization is too low, the adhesion and flexibility of polyvinylpyrrolidone are poor, and the noise reduction effect is correspondingly poor; when the degree of polymerization is too high, the hardness and density of the material will also increase accordingly, which may lead to increased reflection of sound waves on the material surface, thereby reducing the noise reduction performance of the fan volute.

[0018] Optionally, the CoPET further includes silica hollow microsphere powder, wherein the content of silica hollow microsphere powder in the CoPET is 1-10 wt%.

[0019] By adopting the above technical solution, this application incorporates hollow silica microspheres. Hollow silica microspheres are porous, capable of absorbing sound wave energy and effectively absorbing and scattering noise, thus reducing the noise generated during fan operation and achieving a certain degree of noise reduction. Furthermore, hollow silica microspheres can also improve the durability of the fan casing and extend its service life.

[0020] Optionally, the silica hollow microsphere powder is prepared from silicate, water, surfactant, and foaming agent in a weight ratio of 10-15:90-100:1-2:0.5-1.

[0021] Optionally, the silicate is selected from at least one of sodium silicate and potassium silicate; the surfactant is selected from at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate; and the foaming agent is selected from at least one of ammonia, dichlorodifluoromethane, and polyvinyl alcohol.

[0022] Optionally, the method for preparing the silica hollow microsphere powder is as follows: dissolving the silicate in water, adding the surfactant, mixing, adding the foaming agent, stirring and mixing to obtain silicate gel, subjecting the silicate gel to high-temperature heat treatment to form silica hollow microspheres, and pulverizing and classifying them.

[0023] Optionally, the average particle size of the silica hollow microsphere powder is 10–100 μm.

[0024] By adopting the above technical solution, the particle size range of the silica hollow microsphere powder of this application is such that it has good dispersibility, improves the filling effect and stability, and does not adversely affect the processing performance of the fan volute.

[0025] Secondly, this application provides a method for preparing the aforementioned wind turbine volute, comprising the following steps:

[0026] S1. The molten CoPET and PET are fed into the composite spinning box and then into the spinning assembly to produce composite fibers with a CoPET sheath and a PET core layer.

[0027] S2. The composite fibers are laid and needle-punched to obtain a moldable nonwoven fabric.

[0028] S3. The moldable nonwoven fabric is pulled into the mold by the track, and hot molding is performed using a press and a heatable mold. Pressure is maintained to obtain a coarse product.

[0029] S4. The rough product is removed from the mold using a robotic arm and transferred to the punching mold;

[0030] S5. Use a press and a punching die to punch the fan casing. After punching, remove the casing from the punching die and package it.

[0031] By adopting the above technical solution, the preparation process of this application is simple, easy to operate, and has high production efficiency. The prepared fan volute has good noise reduction effect, durability, and high stability.

[0032] By employing hot molding and punching processes, wind turbine casings with complex shapes and precision requirements can be produced quickly and accurately, while significantly reducing production costs.

[0033] Optionally, the CoPET is prepared by dissolving polyvinylpyrrolidone in a solvent, adding PET, stirring, mixing, and drying to obtain the CoPET.

[0034] Optionally, the solvent is water or ethanol.

[0035] By employing the above technical solution, polyvinylpyrrolidone is dissolved in a solvent and then added to PET, which allows for excellent mixing of polyvinylpyrrolidone and PET, resulting in a homogeneous mixture and improved performance. Finally, drying yields dry CoPET, facilitating subsequent processing and use.

[0036] Optionally, in step S3, the mold temperature is 130–220°C.

[0037] Optionally, in step S3, the mold temperature is 160–190°C.

[0038] By adopting the above technical solution, in step S3, a specific mold temperature can effectively hot-mold the composite fibers, resulting in a coarse product with a stable shape and dense structure. Simultaneously, a suitable mold temperature ensures uniform pressure and temperature distribution within the mold, improving product quality and production efficiency.

[0039] Optionally, in step S3, the pressure holding time is 10 to 60 seconds.

[0040] Optionally, in step S3, the pressure holding time is 20 to 40 seconds.

[0041] By adopting the above technical solution, in step S3, the specific holding time can allow the material to undergo sufficient physical and chemical changes during the molding process, thereby achieving the best molding effect.

[0042] Optionally, in step S5, the areal density of the fan casing is 1400-2000 g / m³. 2.

[0043] Optionally, in step S5, the areal density of the fan casing is 1600-1800 g / m³. 2 .

[0044] By adopting the above technical solution, this application can produce a lightweight, noise-reducing, and durable fan casing by using a suitable areal density range. If the areal density is too high, the weight will be heavier; if the areal density is too low, the noise reduction effect will be poor.

[0045] In summary, the present invention has at least one of the following beneficial technical effects:

[0046] 1. This application uses specific raw materials and proportions to produce a fan volute that is durable, lightweight, low-cost, and has good noise reduction effect.

[0047] 2. This application uses polyvinylpyrrolidone to modify PET to obtain CoPET, which has good sound absorption properties.

[0048] 3. The preparation process of this application is simple, easy to operate, and has high production efficiency, which greatly reduces production costs. Detailed Implementation

[0049] The present application will be further described in detail below with reference to the embodiments.

[0050] This application designs a fan volute, the raw material of which includes moldable nonwoven fabric, the moldable nonwoven fabric including bicomponent continuous PET fiber, the bicomponent continuous PET fiber being a composite fiber with a CoPET sheath covering a PET core layer;

[0051] The CoPET comprises polyvinylpyrrolidone and PET, wherein the content of polyvinylpyrrolidone in the CoPET is 1-20 wt%.

[0052] The wind turbine casing of this application is prepared by the following method, including the following steps:

[0053] S1. The molten CoPET and PET are fed into the composite spinning box and then into the spinning assembly to produce composite fibers with a CoPET sheath and a PET core layer.

[0054] S2. The composite fibers are laid and needle-punched to obtain a moldable nonwoven fabric.

[0055] S3. The moldable nonwoven fabric is pulled into the mold by the track, and hot molding is performed using a press and a heatable mold. Pressure is maintained to obtain a coarse product.

[0056] S4. The rough product is removed from the mold using a robotic arm and transferred to the punching mold;

[0057] S5. Use a press and a punching die to punch the fan casing. After punching, remove the casing from the punching die and package it.

[0058] The fan casing proposed in this application has good durability, light weight, low cost, and good noise reduction effect.

[0059] The method for preparing the volute casing of the wind turbine used in this application is simple, easy to operate, and has high production efficiency, which can significantly reduce production costs.

[0060] The raw materials used in this application are as follows:

[0061] PET (Polyethylene terephthalate): CAS: 25038-59-9, Shanghai Maclean Biochemical Technology Co., Ltd.

[0062] Polyvinylpyrrolidone: CAS: 9003-39-8.

[0063] Sodium silicate: CAS: 1344-09-8.

[0064] Sodium dodecyl sulfate: CAS: 151-21-3.

[0065] Polyvinyl alcohol: CAS: 9002-89-5. Specific Implementation

[0067] Examples 1-5

[0068] Example 1

[0069] A method for preparing a wind turbine volute includes the following steps:

[0070] S1. The molten CoPET and PET are fed into the composite spinning box and spun into the spinning assembly to obtain a composite fiber with a CoPET sheath covering a PET core layer. The CoPET content in the composite fiber is 5wt%, the melting point of the CoPET sheath is 210℃, and the melting point of the PET core layer is 260℃.

[0071] S2. The composite fibers are laid and needle punched to obtain a moldable nonwoven fabric with a thickness of 1.5mm.

[0072] S3. The moldable nonwoven fabric is pulled into the mold through the track, and hot molding is performed using a press and a heatable mold to obtain a rough product. The mold temperature is 220℃ and the pressure is held for 10 seconds.

[0073] S4. Use a robotic arm to remove the rough product from the mold and transfer it to the punching mold;

[0074] S5. Using a press and punching die, the fan casing is punched to obtain a surface density of 1400 g / m³. 2 Remove it from the punching die and pack it.

[0075] In step S1 above, the preparation method of CoPET is as follows: dissolve polyvinylpyrrolidone in a solvent, add PET, stir, mix, and dry to obtain CoPET, wherein the content of polyvinylpyrrolidone in CoPET is 1 wt%, and the degree of polymerization of polyvinylpyrrolidone is 10. 6 .

[0076] Example 2

[0077] A method for preparing a wind turbine volute includes the following steps:

[0078] S1. The molten CoPET and PET are fed into the composite spinning box and spun into the spinning assembly to obtain a composite fiber with a CoPET sheath covering a PET core layer. The CoPET content in the composite fiber is 12wt%, the melting point of the CoPET sheath is 200℃, and the melting point of the PET core layer is 265℃.

[0079] S2. The composite fibers are laid and needle punched to obtain a moldable nonwoven fabric with a thickness of 1.5mm.

[0080] S3. The moldable nonwoven fabric is pulled into the mold through the track, and hot molding is performed using a press and a heatable mold to obtain a rough product. The mold temperature is 180℃ and the pressure is held for 40 seconds.

[0081] S4. Use a robotic arm to remove the rough product from the mold and transfer it to the punching mold;

[0082] S5. Using a press and punching dies, punching is performed to obtain the fan volute. The surface density of the fan volute is 1700 g / m³. 2 Remove it from the punching die and pack it.

[0083] In step S1 above, the preparation method of CoPET is as follows: polyvinylpyrrolidone is dissolved in a solvent, PET is added, stirred, mixed, and dried to obtain CoPET. The content of polyvinylpyrrolidone in CoPET is 15 wt%, and the degree of polymerization of polyvinylpyrrolidone is 10. 6 .

[0084] Example 3

[0085] A method for preparing a wind turbine volute includes the following steps:

[0086] S1. The molten CoPET and PET are fed into the composite spinning box and spun into the spinning assembly to obtain a composite fiber with a CoPET sheath covering a PET core layer. The CoPET content in the composite fiber is 10wt%, the melting point of the CoPET sheath is 205℃, and the melting point of the PET core layer is 270℃.

[0087] S2. The composite fibers are laid and needle punched to obtain a moldable nonwoven fabric with a thickness of 1.5mm.

[0088] S3. The moldable nonwoven fabric is pulled into the mold through the track, and hot molding is performed using a press and a heatable mold to obtain a rough product. The mold temperature is 190℃ and the pressure is held for 30 seconds.

[0089] S4. Use a robotic arm to remove the rough product from the mold and transfer it to the punching mold;

[0090] S5. Using a press and punching dies, punching is performed to obtain the fan volute. The surface density of the fan volute is 1600 g / m³. 2 Remove it from the punching die and pack it.

[0091] In step S1 above, the preparation method of CoPET is as follows: dissolve polyvinylpyrrolidone in a solvent, add PET, stir, mix, and dry to obtain CoPET, wherein the content of polyvinylpyrrolidone in CoPET is 10 wt%, and the degree of polymerization of polyvinylpyrrolidone is 10. 6 .

[0092] Example 4

[0093] A method for preparing a wind turbine volute includes the following steps:

[0094] S1. The molten CoPET and PET are fed into the composite spinning box and spun into the spinning assembly to obtain a composite fiber with a CoPET sheath covering a PET core layer. The CoPET content in the composite fiber is 15wt%, the melting point of the CoPET sheath is 195℃, and the melting point of the PET core layer is 265℃.

[0095] S2. The composite fibers are laid and needle punched to obtain a moldable nonwoven fabric with a thickness of 1.5mm.

[0096] S3. The moldable nonwoven fabric is pulled into the mold through the track, and hot molding is performed using a press and a heatable mold to obtain a rough product. The mold temperature is 160℃ and the pressure is held for 20 seconds.

[0097] S4. Use a robotic arm to remove the rough product from the mold and transfer it to the punching mold;

[0098] S5. Using a press and punching dies, punching is performed to obtain the fan volute. The surface density of the fan volute is 1800 g / m³. 2 Remove it from the punching die and pack it.

[0099] In step S1 above, the preparation method of CoPET is as follows: polyvinylpyrrolidone is dissolved in a solvent, PET is added, stirred, mixed, and dried to obtain CoPET. The content of polyvinylpyrrolidone in CoPET is 20 wt%, and the degree of polymerization of polyvinylpyrrolidone is 10. 6 .

[0100] Example 5

[0101] A method for preparing a wind turbine volute includes the following steps:

[0102] S1. The molten CoPET and PET are fed into the composite spinning box and spun into the spinning assembly to obtain a composite fiber with a CoPET sheath covering a PET core layer. The CoPET content in the composite fiber is 30wt%, the melting point of the CoPET sheath is 190℃, and the melting point of the PET core layer is 260℃.

[0103] S2. The composite fibers are laid and needle punched to obtain a moldable nonwoven fabric with a thickness of 1.5mm.

[0104] S3. The moldable nonwoven fabric is pulled into the mold through the track, and hot molding is performed using a press and a heatable mold to obtain a rough product. The mold temperature is 130℃ and the pressure is held for 60 seconds.

[0105] S4. Use a robotic arm to remove the rough product from the mold and transfer it to the punching mold;

[0106] S5. Using a press and punching dies, punching is performed to obtain the fan volute. The surface density of the fan volute is 2000 g / m³. 2 Remove it from the punching die and pack it.

[0107] In step S1 above, the preparation method of CoPET is as follows: polyvinylpyrrolidone is dissolved in a solvent, PET is added, stirred, mixed, and dried to obtain CoPET. The content of polyvinylpyrrolidone in CoPET is 5 wt%, and the degree of polymerization of polyvinylpyrrolidone is 10. 6 .

[0108] Comparative Examples 1-2

[0109] Comparative Example 1

[0110] The difference between Comparative Example 1 and Example 2 is that in Comparative Example 1, CoPET was replaced with an equal amount of PET.

[0111] Comparative Example 2

[0112] The difference between Comparative Example 2 and Example 2 is that the content of polyvinylpyrrolidone in the CoPET of Comparative Example 2 is 30 wt%.

[0113] Experimental testing

[0114] Testing items and testing methods

[0115] The sound absorption coefficient of the fan casing was tested according to GB / T 18696.2-2002 "Measurement of sound absorption coefficient and acoustic impedance in acoustic impedance tubes - Part 2: Transfer function method".

[0116] The SW series impedance tube testing system from Beijing Shengwang Company was used.

[0117] The sound absorption coefficients of the fan casings prepared in Examples 1-5 and Comparative Examples 1-2 were tested, and the test results are shown in Table 1.

[0118] Table 1

[0119] frequency 800Hz 1000Hz 1250Hz 1600Hz 2000Hz Example 1 0.152 0.268 0.601 0.712 0.825 Example 2 0.165 0.282 0.619 0.727 0.836 Example 3 0.159 0.275 0.613 0.720 0.834 Example 4 0.158 0.273 0.611 0.718 0.830 Example 5 0.155 0.270 0.608 0.715 0.827 Comparative Example 1 0.062 0.094 0.142 0.216 0.306 Comparative Example 2 0.105 0.213 0.489 0.562 0.701

[0120] As shown in Table 1, the fan casings prepared in Examples 1-5 exhibit excellent noise reduction effects, far exceeding those of Comparative Example 1 and Comparative Example 2. The fan casings prepared in Examples 2-4 demonstrate even better noise reduction effects than those in Examples 1 and 5.

[0121] Comparative Example 1, which does not contain CoPET modified with polyvinylpyrrolidone, showed a significant decrease in noise reduction.

[0122] The content of polyvinylpyrrolidone in the CoPET skin of Comparative Example 2 was 30 wt%, and the noise reduction effect of the resulting fan volute was significantly lower than that of Example 2.

[0123] Examples 6-14

[0124] Example 6

[0125] The difference between Example 6 and Example 2 is that the content of CoPET in the composite fiber in Example 6 is 40 wt%.

[0126] Example 7

[0127] The difference between Example 7 and Example 2 is that in Example 7, the degree of polymerization of polyvinylpyrrolidone is 80,000.

[0128] Example 8

[0129] The difference between Example 8 and Example 2 is that in Example 8, the degree of polymerization of polyvinylpyrrolidone is 100,000.

[0130] Example 9

[0131] The difference between Example 9 and Example 2 is that in Example 9, the degree of polymerization of polyvinylpyrrolidone is 500,000.

[0132] Example 10

[0133] The difference between Example 10 and Example 2 is that in Example 10, silica hollow microsphere powder was also added to the CoPET, and the content of silica hollow microsphere powder in the CoPET was 5 wt%.

[0134] The preparation method of silica hollow microsphere powder is as follows: sodium silicate is dissolved in water, sodium dodecyl sulfate is added and mixed, polyvinyl alcohol is added and stirred to obtain silicate gel. The silicate gel is subjected to high-temperature heat treatment to form silica hollow microspheres, which are then pulverized and classified. The weight ratio of sodium silicate, water, sodium dodecyl sulfate, and polyvinyl alcohol is 12:95:1.5:1, and the average particle size of the silica hollow microsphere powder is 10 μm.

[0135] Example 11

[0136] The difference between Example 11 and Example 10 is that in Example 11, the content of silica hollow microsphere powder in CoPET is 1 wt%.

[0137] Example 12

[0138] The difference between Example 12 and Example 10 is that in Example 12, the content of silica hollow microsphere powder in CoPET is 10 wt%.

[0139] Example 13

[0140] The difference between Example 13 and Example 10 is that in Example 13, the average particle size of the silica hollow microsphere powder is 50 μm.

[0141] Example 14

[0142] The difference between Example 14 and Example 10 is that in Example 14, the average particle size of the silica hollow microsphere powder is 100 μm.

[0143] The sound absorption coefficient of the fan casings prepared in Examples 6 to 14 was tested, and the test results are shown in Table 2.

[0144] Table 2

[0145] frequency 800Hz 1000Hz 1250Hz 1600Hz 2000Hz Example 6 0.163 0.279 0.615 0.724 0.832 Example 7 0.158 0.274 0.611 0.719 0.830 Example 8 0.162 0.278 0.613 0.722 0.831 Example 9 0.169 0.292 0.625 0.734 0.842 Example 10 0.176 0.305 0.415 0.750 0.854 Example 11 0.173 0.302 0.639 0.745 0.851 Example 12 0.174 0.303 0.641 0.747 0.852 Example 13 0.180 0.312 0.420 0.753 0.858 Example 14 0.178 0.309 0.417 0.751 0.856

[0146] As can be seen from the test results in Table 2, in Example 6, the content of CoPET in the composite fiber was 40 wt%, and the noise reduction effect of the resulting fan volute was lower than that in Example 2.

[0147] In Examples 7-9, the degree of polymerization of polyvinylpyrrolidone was different. Among them, the fan volute prepared in Example 9 had the best noise reduction effect, which was higher than that in Example 2.

[0148] Examples 10-14 also incorporated silica hollow microsphere powder, and the resulting fan volutes all exhibited better noise reduction effects than those in Examples 1-5.

[0149] In Examples 10-12, the content of silica hollow microsphere powder in CoPET is different. Among them, the fan volute prepared in Example 10 has the best noise reduction effect.

[0150] In Examples 10, 13, and 14, the average particle size of the silica hollow microsphere powder is different. Among them, the fan volute prepared in Example 13 has the best noise reduction effect.

[0151] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A fan casing, characterized in that, The raw materials include moldable nonwoven fabric, which includes bicomponent continuous PET fiber, and the bicomponent continuous PET fiber is a composite fiber in which the sheath layer CoPET is coated with the core layer PET. The CoPET comprises polyvinylpyrrolidone, PET, and silica hollow microspheres. The content of polyvinylpyrrolidone in the CoPET is 1-20 wt%, and the content of silica hollow microspheres in the CoPET is 1-10 wt%. The degree of polymerization of the polyvinylpyrrolidone is 10. 5 ~10 6 The method for preparing the silica hollow microsphere powder is as follows: sodium silicate is dissolved in water, sodium dodecyl sulfate is added and mixed, polyvinyl alcohol is added and stirred to obtain silicate gel, the silicate gel is subjected to high-temperature heat treatment to form silica hollow microspheres, and then pulverized and graded. The weight ratio of sodium silicate, water, sodium dodecyl sulfate and polyvinyl alcohol is 12:95:1.5:1, and the average particle size of the silica hollow microsphere powder is 10~100 μm.

2. The fan casing according to claim 1, characterized in that, The content of CoPET in the composite fiber is 5~30wt%.

3. The fan casing according to claim 1, characterized in that, The CoPET has a melting point of 190~210℃, and the core PET has a melting point of 260~270℃.

4. A method for preparing the fan volute according to claim 1, characterized in that, Includes the following steps: S1. The molten CoPET and PET are fed into the composite spinning box and then into the spinning assembly to produce composite fibers with a CoPET sheath and a PET core layer. S2. The composite fibers are laid and needle-punched to obtain a moldable nonwoven fabric. S3. The moldable nonwoven fabric is pulled into the mold by the track, and hot molding is performed using a press and a heatable mold. Pressure is maintained to obtain a coarse product. S4. The rough product is removed from the mold using a robotic arm and transferred to the punching mold; S5. Use a press and a punching die to punch the fan casing. After punching, remove the casing from the punching die and package it.

5. The method for preparing the fan volute according to claim 4, characterized in that, The preparation method of CoPET is as follows: dissolve the polyvinylpyrrolidone in a solvent, add PET, stir, mix, and dry to obtain CoPET.

6. The method for preparing the fan volute according to claim 4, characterized in that, In step S3, the mold temperature is 130~220℃, and the holding time is 10~60s. In step S5, the areal density of the fan casing is 1400~2000g / m³. 2 .