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Method for reducing cracking of dry-pressing molded strontium ferrite external-radial multi-polar magnetic ring

A strontium ferrite and multi-pole magnetic ring technology is applied in the field of reducing the cracking of dry-pressed strontium ferrite external radial multi-pole magnetic rings, and can solve the problem of increasing the unsafe factors in the production process, the magnetic leakage of the splicing gap, and increasing the production cost. and other problems, to achieve the effect of reducing the radial uneven shrinkage trend, no cracking problem, and improving product yield.

Active Publication Date: 2019-02-22
HUNAN AEROSPACE MAGNET & MAGNETO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Conventional permanent magnet rotors are spliced ​​by multiple pieces of magnetic tiles, which usually have the following disadvantages: 1) Difficulty in assembly; 2) Flux leakage in the splicing gap; 3) Non-sinusoidal distribution of surface magnetic flux, which makes the motor have obvious torque ripple and Cogging effect, high energy consumption and high noise
Therefore, this mold structure causes frequent damage to the upper and lower molds and cavity liners, which greatly increases production costs, reduces production efficiency, and increases unsafe factors in the production process

Method used

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  • Method for reducing cracking of dry-pressing molded strontium ferrite external-radial multi-polar magnetic ring
  • Method for reducing cracking of dry-pressing molded strontium ferrite external-radial multi-polar magnetic ring
  • Method for reducing cracking of dry-pressing molded strontium ferrite external-radial multi-polar magnetic ring

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] (1) Take 100 kg of Y35 strontium ferrite dry-pressed powder, add 1 kg of camphor powder and 1 kg of calcium stearate, stir and mix at 800 r / min for 180 min, then pass 60 Mesh sieve to get mixed powder;

[0032] (2) Fill the mixed powder obtained in step (1) into the mold, and then press it into a ring green body. The structure of the mold is as follows: Figure 1-3 As shown; during molding, by applying a radial 4-pole magnetic field on the outer edge of the middle mold, the green body has an outer radial 4-pole orientation, the molding pressure is 25 MPa, the forming magnetic field strength is 5000 Oe, and the obtained green body has a density of 2.8 g / cm 3 ;

[0033] (3) Place the obtained body in an electric kiln, heat up to 1200°C at a rate of 3°C / min, sinter for 1.5 h, and grind;

[0034] (4) Magnetize and inspect the ground product.

[0035]The results show that the average value of the peak value of the surface magnetic flux density of the obtained ferrite out...

Embodiment 2

[0037] (1) Take 100 kg of Y45 strontium ferrite dry-pressed powder, add 1 kg of camphor powder, add 0.5 kg of stearic acid amide (-325 mesh) and 0.5 kg of oleic acid amide (-325 mesh), and stir Mixing, the rotating speed is 29000 r / min, the time is 5min, then passes through a 40 mesh sieve to obtain the mixed powder;

[0038] (2) Fill the mixed powder obtained in step (1) into the mold, and then press and form it into a ring green body. The mold structure is as follows: Figure 1-3 As shown; during molding, by applying a radial 4-pole magnetic field on the outer edge of the middle mold, the green body has an outer radial 4-pole orientation, the molding pressure is 12 MPa, the forming magnetic field strength is 8000 Oe, and the obtained green body has a density of 2.85 g / cm 3 ;

[0039] (3) Place the obtained body in an electric kiln, heat up to 1145°C at a rate of 3°C / min, sinter for 2.5 hours, and grind;

[0040] (4) Magnetize and inspect the ground product.

[0041] The ...

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Abstract

The invention provides a method for reducing cracking of a dry-pressing molded strontium ferrite external-radial multi-polar magnetic ring. The method comprises the following steps that (1) prepared strontium ferrite magnetic powder is taken, a lubrication binder is added, mixing and sieving are conducted, and mixed powder is obtained; (2) a mold is filled with the mixed powder obtained in the step (1), pressure forming is conducted, thus an annular blank is obtained, during forming, a radial 2n pole magnetic field is applied to the outer edge of the mold, and thus external-radial 2n magneticpole orientation of the blank is generated, wherein n is a natural number from 1 to 24; (3) the annular blank obtained after forming is sintered, ground and cleaned, and thus the dry-pressing molded strontium ferrite external-radial multi-polar magnetic ring is obtained; and (4) a finished product is obtained after multi-polar magnetizing and surface magnetic flux density detecting. The method hasthe advantages that the mold is simple in structure, production is stable, the cost is low, safety and reliability are achieved, the obtained magnetic ring is high in performance and high in finishedproduct rate, and the cracking problem is avoided.

Description

technical field [0001] The invention relates to a method for reducing the cracking of a dry-pressed strontium ferrite external radial multi-pole magnetic ring. Background technique [0002] Since 2009, the scale of the global motor market has continued to expand, and countries have increasingly higher requirements for motor energy efficiency, resulting in a significant increase in the market demand for brushless motors (energy efficiency levels up to IE3 and above), with broad prospects for development. The permanent magnet rotor is a key component of brushless motors, and its market demand has also surged accordingly. Conventional permanent magnet rotors are spliced ​​by multiple pieces of magnetic tiles, which usually have the following disadvantages: 1) Difficulty in assembly; 2) Flux leakage in the splicing gap; 3) Non-sinusoidal distribution of surface magnetic flux, which makes the motor have obvious torque ripple and Cogging effect, high energy consumption and high n...

Claims

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Application Information

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IPC IPC(8): C04B35/26C04B35/622H01F41/02H01F1/113
CPCC04B35/2683C04B35/622C04B2235/6562C04B2235/6567H01F1/113H01F41/0266
Inventor 姚锐刘超郑自儒陈晓宇邓雅之
Owner HUNAN AEROSPACE MAGNET & MAGNETO
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