TW202046350A - Method for manufacturing polar anisotropic magnetic ring - Google Patents

Abstract

A method for manufacturing polar anisotropic magnetic ring is disclosed, and the method comprises steps of: providing slurry with magnetic powders comprising liquids and solids in a solid content of 65±5%, wherein the slurry with magnetic powders comprises following solids in weight percent: 0.1 to 0.5% of silicon oxide, 0.1 to 1.0% of calcium carbonate, 0.1 to 1.0% of cobalt oxide, 0.1 to 1.0% of strontium carbonate, and the rest is supplemented to 65±5% with standard strontium ferrite calcined material; injecting the slurry with magnetic powders into an annular mold, and applying a first magnetic field to the slurry with magnetic powders in the annular mold to form a first original body, the first magnetic field has a magnetization of 10,000 Oe or more; and performing a drying and granulation process, a stamping and orientation process, and a sintering process to the first original body in sequence to form a polar anisotropic magnetic ring.

Description

Manufacturing method of polar anisotropic magnetic ring

The present invention relates to a method for manufacturing a magnetic component, in particular to a method for manufacturing a polar anisotropic magnetic ring that is pre-aligned by a wet process.

The mold design of permanent ferrite material is simple, and the production speed is fast, and it has the advantages of low eddy current loss, high Curie temperature and oxidation resistance. Due to the high cost performance, it has become the most widely used permanent magnet material. Class electronic and electrical products.

With the increasing awareness of energy conservation, the demand for high-performance BLDC motors (or motors) is increasing. Among them, high-characteristic permanent ferrite materials are key materials in motors. For example, in general, BLDC motor rotors are mostly assembled with tile-shaped segment magnets or radiating anisotropic ring-shaped magnets.

However, the patch assembly process is complicated, and the rotor balance is easy to cause. In addition, as shown in Figure 1, the surface magnetic flux distribution of the conventional radiating anisotropic magnetic ring 9 is non-standard sine wave, such as a motor rotor. During operation, a cogging torque is generated between the magnet and the stator, which in turn causes vibration and noise.

Compared with the above two types of magnets, the pole anisotropic ring type sintered ferrite magnet is a multi-pole magnetized one-body molded magnet. As shown in Figure 2, the magnetic flux between the poles of the conventional pole anisotropic magnetic ring 8 will be The arched path is from the N pole to the S pole, and due to the surface magnetization, the surface magnetic flux density distribution of the magnet is close to a sine wave. In the motor operation design, the torque is small, which can effectively reduce the operating vibration and noise.

In addition, since the polar anisotropic magnetic ring has a higher surface magnetic flux density and total magnetic flux, in general, the surface magnetic flux of the polar anisotropic magnetic ring is 1.5 times higher than the surface magnetic flux of the radiating anisotropic magnetic ring. The magnetic ring can achieve better motor output efficiency, so it is widely used in products with high performance requirements, such as air conditioner indoor unit fan motors or stepping motors.

In the manufacturing process of the conventional polar anisotropic magnetic ring, the coercive force in the magnetic properties of ferrite is closely related to the size of the grinding particle size. In theory, the closer to the single magnetic zone size condition (~0.3μm), the better the magnet can be obtained. Coercivity characteristics. However, when the particle size of the magnetic powder is less than 0.6 μm, the slurry will have poor drainage performance during molding. Therefore, the conventional permanent ferrite fine pulverization process is usually controlled at 0.7 μm or more in order to balance the process yield and the characteristics of the finished magnet.

Different from the tile forming magnet, the conventional heterocubic magnet is a ring magnet, and the filling depth during forming is relatively deep. It will be difficult to evenly fill the 0.7μm fine powder into the mold cavity, which is easy to cause after forming The density of the upper and lower parts of the green embryo is uneven, which affects the sintering yield.

For example, as shown in Fig. 3, the conventional manufacturing method of polar anisotropic magnetic ring usually includes a material preparation step S81, a dry pre-alignment step S82, and a post-production step S83. For example, the finely pulverized magnetic powder is first After the granulation process, fill the mold cavity to complete the multi-pole alignment process. In order to increase the internal magnetic moment of the granulated magnetic powder into an orderly arrangement, the alignment (or pre-alignment) is usually added once before the granulation. However, the primary alignment stage of the conventional polar anisotropic magnet adopts a dry alignment granulation process. This process is not only complicated, but the dry process will cause excessive friction between the magnetic powders, which is not conducive to improving the magnetic flux characteristics of the magnet surface. improve.

In view of this, it is necessary to provide a technical solution that is different from the past to solve the problems of conventional technologies.

One objective of the present invention is to provide a method for manufacturing a polar anisotropic magnetic ring, which uses a wet process for pre-alignment, so as to reduce the friction between the magnetic powders and thereby improve the magnetic flux characteristics of the magnetic ring surface.

In order to achieve the above objective, the present invention provides a method for manufacturing a polar anisotropic magnetic ring, which includes the steps of: a material preparation step, providing a magnetic powder slurry, the magnetic powder slurry including liquid and solid, and the solid content of the magnetic powder slurry is 65± 5%, the magnetic powder slurry includes the following solids by weight percentage: 0.1 to 0.5% of silicon oxide, 0.1 to 1.0% of calcium carbonate, 0.1 to 1.0% of cobalt oxide, 0.1 to 1.0% of strontium carbonate, and the rest are standard strontium ferrite The body sintering material is made up to 65±5%; a wet pre-alignment step is to inject the magnetic powder slurry into an annular mold, and apply a first magnetic field to the magnetic powder slurry in the annular mold to form a first embryo , The magnetization of the first magnetic field is more than 10000 Oe; and a post-production step, a drying granulation process, a stamping alignment process and a sintering process are sequentially performed on the first embryo body to form a Very different square magnetic ring.

In an embodiment of the present invention, in the wet pre-alignment step, the magnetic powder slurry is first added with a binder and then applied to the first magnetic field. The viscosity of the binder is less than 10 cP and the molecular weight is less than 50,000.

In an embodiment of the present invention, the adhesive may be a polyvinyl alcohol adhesive.

In an embodiment of the present invention, in the wet pre-alignment step, when the first magnetic field is applied, a pressure can be applied to the magnetic powder slurry in the annular mold, so that the density of the first embryo body can be Between 2.1 to 3.0 g/cm3.

In an embodiment of the present invention, the density of the first embryo body may range from 2.3 to 2.7 g/cm ^ 3.

In an embodiment of the present invention, in the material preparation step, the standard strontium-based ferrite sintered material can be subjected to a wet ball milling process. In the wet ball milling process, silicon oxide, calcium carbonate, and oxide can be added. Cobalt and strontium carbonate.

In an embodiment of the present invention, during the wet ball milling process, the standard strontium-based ferrite burnt material is ball milled into a number of spheres, and the outer diameter of the spheres may be between 0.6 and 0.8 microns.

In an embodiment of the present invention, during the drying and granulation process, the first embryo body can be broken into a plurality of second scraps after being dried, and the second scraps are sieved according to a desired particle size. Part of it is a number of third corpuscles.

In an embodiment of the present invention, during the stamping and alignment process, the third granular body is stamped to form a fourth ring body, and a second magnetic field can be applied to the fourth ring body so that the fourth ring body has For several radial magnetic poles, the magnetization of the second magnetic field is not less than 10,000 ohms.

In an embodiment of the present invention, during the sintering process, the fourth ring body can be placed in a sintering environment at 1230 to 1245 degrees Celsius and maintained at a temperature for at least one hour to form the polar anisotropic magnetic ring.

The manufacturing method of the polar anisotropic magnetic ring of the present invention can improve the shortcomings of the complicated process of the conventional dry process, and can overcome the problem of excessive friction between the magnetic powder caused by the conventional dry process by using a simpler wet pre-alignment process. The magnet characteristics of the products made by the manufacturing method of the above-mentioned embodiments of the present invention are significantly better than those of the conventional manufacturing process. For example, on the basis of the same ingredient formula, the products made by the present invention have higher magnet alignment and effectively improve the surface magnetism. The density is more than 10%. Therefore, the above-mentioned embodiments of the present invention can achieve the effects of obtaining better motor output efficiency, which is beneficial to be widely used in products with high performance requirements, such as air conditioner indoor unit fan motors or stepping motors.

In order to make the above and other objects, features, and advantages of the present invention more obvious and understandable, the following will specifically cite the preferred embodiments of the present invention, together with the accompanying drawings, and describe in detail as follows. Furthermore, the directional terms mentioned in the present invention, such as up, down, top, bottom, front, back, left, right, inside, outside, side, surrounding, center, horizontal, horizontal, vertical, vertical, axial, The radial direction, the uppermost layer or the lowermost layer, etc., are only the direction of reference to the attached drawings. Therefore, the directional terms used are used to describe and understand the present invention, rather than to limit the present invention.

Referring to FIG. 4, the manufacturing method of a polar anisotropic magnetic ring according to an embodiment of the present invention may include steps: a material preparation step S1, a wet pre-alignment step S2, and a post-production step S3. Examples are as follows, but not limited to this.

For example, as shown in Figure 4, in the material preparation step S1, a magnetic powder slurry can be provided. For example, the magnetic powder slurry includes liquid and solid, and the solid content of the magnetic powder slurry is 65±5%. The magnetic powder slurry includes the following solids by weight percentage: 0.1 to 0.5% of silicon oxide (SiO2), 0.1 to 1.0% of calcium carbonate (CaCO3), 0.1 to 1.0% of cobalt oxide (CoO), and 0.1 to 1.0% of strontium carbonate (SrCO3) , The rest is made up to 65±5% with standard strontium ferrite sintered material.

In one embodiment, in the material preparation step S1, the standard strontium-based ferrite sintered material is subjected to a wet ball milling process. In the wet ball milling process, silicon oxide, calcium carbonate, cobalt oxide and strontium carbonate are added For example, in the wet ball milling process, the standard strontium ferrite sintered material can be ball milled into several spheres, and the outer diameter of the spheres can range from 0.6 to 0.8 microns (μm), for example: 0.60, 0.65, 0.70, 0.75, 0.80 microns, etc., but not limited to this. In this way, it can be avoided that when the particle size of the magnetic powder is less than 0.6 μm, poor drainage during slurry molding can be avoided, so as to balance the process yield and the characteristics of the magnet product.

As shown in Figure 4, in the wet pre-alignment step S2, the magnetic powder slurry can be injected into an annular mold, for example: the mold cavity corresponds to the mold of the magnetic ring product, and the magnetic powder slurry in the annular mold A first magnetic field is applied to form a first embryo body. The magnetization intensity of the first magnetic field is above 10,000 Oe, such as: 11,000, 12,000, 13,000, 15,000, 17,000, 20,000 Oe, etc., but not limit.

In one embodiment, in the wet pre-alignment step S2, when the first magnetic field is applied, a pressure may be applied to the magnetic powder slurry in the ring mold so that the density of the first embryo body can be adjusted. At 2.1 to 3.0 grams/cubic centimeter (g/cm ³ ), for example: 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, etc., the density of the first embryo may be further between 2.3 to 2.7 g/cm ³ , for example: 2.33, 2.35, 2.37, 2.42, 2.45, 2.48, 2.51, 2.53, 2.55, 2.57, 2.59, 2.63, 2.65, 2.67, etc., to further improve the magnetic ring characteristics.

In one embodiment, in the wet pre-alignment step S2, the magnetic powder slurry may be added with a bonding agent and then applied to the first magnetic field. The viscosity of the bonding agent is less than 10 cP (dyne-S/cm ² ) And the molecular weight is less than 50000, for example: the viscosity is 5, 6, 7, 8, 9, 9.5, etc., and the molecular weight is 25000, 30000, 35000, 40000, 45000, etc., for example: the binder can be polyvinyl alcohol (PVA) Adhesives, etc., to facilitate access and reduce manufacturing costs. In this way, a low-viscosity and low-polymer binder can be used to assist in improving the strength of the material particles after subsequent granulation.

As shown in Figure 4, in the post-production step S3, a drying granulation process, a stamping alignment process, and a sintering process can be sequentially performed on the first green body to form a pole anisotropic magnetic ring. Examples are as follows.

For example, in the drying and granulation process, the first embryo is dried and then broken into a plurality of second scraps, and a part of the second scraps is sieved according to a desired particle size as the plurality of thirds. Granules, for example, can be broken up using equipment such as a swing granulator, and sieved through a screen to obtain the required particle size. The obtained granulated magnetic powder can be tested according to international IEC 404-5, Japanese JIS C2501, 2502, for example. Standard analysis of magnetic properties; in addition, the degree of alignment can also be judged by the squareness (H _k /H _cj ratio). In this way, the first embryo body can be dried and broken up to obtain particles of appropriate size to facilitate subsequent manufacturing processes.

In addition, during the stamping and alignment process, the third granule is stamped to form a fourth ring body, and a second magnetic field is applied to the fourth ring body so that the fourth ring body has a plurality of radial magnetic poles. The magnetization of the second magnetic field is not less than 10,000 ohms, such as 10,000, 11,000, 12,000, 13,000, 15,000, etc., but not limited to this. In this way, the granular body can be pressed into a ring body for the second magnetization and alignment process to facilitate the production of magnetic rings with multiple magnetic levels.

In addition, during the sintering process, the fourth ring body is placed in a sintering environment of 1230 to 1245 degrees Celsius and the temperature is maintained for at least one hour, for example: it can be at 1231, 1235, 1237, 1239, 1241, 1245 degrees Celsius as required Waiting for the temperature and holding the temperature for 1 hour, etc., but not limited to this, the temperature and time can also be fine-tuned according to actual needs to form the above-mentioned polar anisotropic magnetic ring embodiment. In this way, the magnetic ring that has generated multiple magnetic levels can be further sintered and shaped, and the surface magnetic flux characteristics can be further analyzed later.

The following examples illustrate the experimental results of samples made according to the above-mentioned embodiments of the present invention. Sample 1 is a polar anisotropic magnetic ring sample made according to the wet pre-alignment process of the above-mentioned embodiment of the present invention. The polar anisotropic magnetic ring samples made by the alignment process, these magnetic ring samples 1 and 2 were specially developed into powder for comparison. For example, the production process of sample 1 is roughly as follows: raw material powder system process è wet pre-alignment process è drying and granulation process è stamping and multi-level alignment è sintering è grinding è magnetizing test. The details are as described above. The final molded magnet sample 1 is a 24-pole ring magnet sample of φ 30.2 mm (mm) × φ 21.1 mm × t 25.1 mm; sample 2 and sample 1 use the same formula, the difference is: sample 1 adopts the above-mentioned embodiment of the present invention It was made by wet pre-alignment process, and sample 2 was made by conventional dry pre-alignment process. The production process of sample 2 is roughly as follows: raw powder system process è water filtration, drying, crushing è dry powder pre-alignment process è granulation process è stamping forming and multi-pole alignment è sintering è grinding è magnetizing test, and finally forming the magnet Sample 2 is also a 24-pole ring magnet sample measuring φ 30.2 mm (mm) × φ 21.1 mm × t 25.1 mm.

Table 1 Comparison table of the characteristics of granulated magnetic powder and the magnetic characteristics of multi-pole magnets B _r (G) bH _c (Oe) iH _c (Oe) (BH) _m (MGOe) (H _k /H _cj ) Surface magnetic flux density (G) Sample 1 (Invention) 3651 3013 3308 3.082 0.88 2250 Sample 2 (known) 3591 2932 3280 2.970 0.80 2045

Among them, the granulated magnetic powder characteristics and multi-pole magnet surface magnetic characteristics of sample 1 and sample 2 are shown in Table 1, and the surface magnetic characteristic curves of sample 1 and sample 2 are shown as D1 and D2 in Fig. 5. From the surface magnetic characteristic curves D1 and D2 in Table 1 and Figure 5, it can be seen that the magnetic characteristics of the magnetic ring samples made in the above embodiments of the present invention are significantly better than those of the conventional magnetic ring samples, for example: The alignment of the prepared magnetic ring sample can reach above 0.88 (better than the conventional 0.80), and the surface magnetic flux density can reach 2250G (better than the conventional 2045G).

Based on the same formula of the magnetic ring samples made in the above-mentioned embodiment of the present invention and the conventional manufacturing process, the present invention can effectively increase the surface magnetic flux density of the polar anisotropic magnetic ring by more than 10%, and the product alignment of the present invention is higher than that of conventional products. Know products. Therefore, the product of the present invention can obtain better motor output efficiency compared with conventional products, which is beneficial to be widely used in products with high performance requirements, such as fan motors or stepping motors of indoor air conditioners.

Furthermore, the manufacturing method of the polar anisotropic magnetic ring of the above embodiment of the present invention can improve the disadvantages of the complicated process of the conventional manufacturing process, and the friction between the magnetic powders caused by the conventional dry process can be overcome by using a simpler wet pre-alignment process. The problem of excessive force makes the magnet characteristics of the product made by the manufacturing method of the above embodiment of the present invention significantly better than the conventional manufacturing process, for example: on the basis of the same ingredient formula, the product made by the present invention has a higher degree of magnet alignment And effectively increase the surface magnetic flux density by more than 10%.

Therefore, the above-mentioned embodiment of the present invention can achieve better motor output efficiency compared with the conventional manufacturing process, which is beneficial to be widely used in products with high performance requirements, such as air-conditioning indoor unit fan motors or stepping motors, and is beneficial to improve the overall motor Quality and customer experience satisfaction.

Although the present invention has been disclosed in preferred embodiments, it is not intended to limit the present invention. Anyone who is familiar with the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be subject to the scope of the attached patent application.

9: Radiating anisotropic magnetic ring 8: Polar anisotropic magnetic ring D1: Curve D2: Curve N: magnetic pole S: magnetic pole S1: Preparation steps S2: Wet pre-alignment step S3: Post-production steps S81: Preparation steps S82: Dry pre-alignment steps S83: Post-production steps

[Picture 1]: A schematic diagram of the surface magnetic flux distribution of a conventional radiating anisotropic magnetic ring. [Figure 2]: Schematic diagram of the magnetic flux distribution on the surface of the conventional polar anisotropic magnetic ring. [Picture 3]: The flow block diagram of the manufacturing method of the conventional polar anisotropic magnetic ring. [Figure 4]: A flow block diagram of a method of manufacturing a polar anisotropic magnetic ring according to an embodiment of the present invention. [Figure 5]: Schematic diagram of the surface magnetic characteristic curves of the polar anisotropic magnetic ring manufactured by the present invention and the polar anisotropic magnetic ring manufactured by a conventional method.

S1: Preparation steps

S2: Wet pre-alignment step

S3: Post-production steps

Claims (10)

A manufacturing method of a polar anisotropic magnetic ring, including the steps: In a material preparation step, a magnetic powder slurry is provided, the magnetic powder slurry includes liquid and solid, the solid content of the magnetic powder slurry is 65±5%, and the magnetic powder slurry includes the following solids by weight percentage: silicon oxide 0.1 to 0.5% , Calcium carbonate 0.1 to 1.0%, cobalt oxide 0.1 to 1.0%, strontium carbonate 0.1 to 1.0%, and the rest is made up to 65±5% with standard strontium ferrite sintering material; In a wet pre-alignment step, the magnetic powder slurry is poured into an annular mold, and a first magnetic field is applied to the magnetic powder slurry in the annular mold to form a first embryo. The magnetization intensity of the first magnetic field is 10,000 ohms. Above; and In a post-production step, a drying granulation process, a stamping alignment process and a sintering process are sequentially performed on the first embryo body to form a pole anisotropic magnetic ring. The manufacturing method of the polar anisotropic magnetic ring described in the first item of the scope of patent application, wherein in the wet pre-alignment step, the magnetic powder slurry is first added with a bonding agent and then the first magnetic field is applied, the bonding agent The viscosity is less than 10cP and the molecular weight is less than 50,000. According to the manufacturing method of the polar anisotropic magnetic ring described in item 2 of the scope of patent application, the adhesive is a polyvinyl alcohol adhesive. The manufacturing method of the polar anisotropic magnetic ring as described in the first item of the scope of patent application, wherein in the wet pre-alignment step, when the first magnetic field is applied, a pressure is applied to the magnetic powder slurry in the ring mold , So that the density of the first embryo body is between 2.1 to 3.0 g/cm ^ 3. According to the manufacturing method of the polar anisotropic magnetic ring described in item 4 of the scope of patent application, the density of the first embryo body is between 2.3 and 2.7 g/cm ^ 3. The manufacturing method of the polar anisotropic magnetic ring as described in item 1 of the scope of patent application, wherein in the material preparation step, the standard strontium-based ferrite sintered material undergoes a wet ball milling process, and in the wet ball milling process , Add silicon oxide, calcium carbonate, cobalt oxide and strontium carbonate. The manufacturing method of the polar anisotropic magnetic ring as described in item 6 of the scope of patent application, wherein in the wet ball milling process, the standard strontium ferrite sintered material is ball milled into a number of spheres, the outer diameter of the sphere At 0.6 to 0.8 microns. As described in the first item of the scope of patent application, the manufacturing method of the polar anisotropic magnetic ring, wherein in the drying and granulation process, the first embryo is dried and then broken into a number of second scraps, according to a desired The particle size screen takes a part of the second crushed material as a plurality of third granules. The method for manufacturing a polar anisotropic magnetic ring as described in item 8 of the scope of patent application, wherein in the stamping and alignment process, the third granule is stamped to form a fourth ring body, and a second ring is applied to the fourth ring body. Two magnetic fields, so that the fourth ring body has several radial magnetic poles, and the magnetization of the second magnetic field is not less than 10,000 ohms. According to the method for manufacturing a polar anisotropic magnetic ring described in item 9 of the scope of patent application, in the sintering process, the fourth ring body is placed in a sintering environment at 1230 to 1245 degrees Celsius and the temperature is maintained for at least one hour, To form the pole anisotropic magnetic ring.

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