CN112679215A - Method for dry pressing and forming permanent magnetic ferrite - Google Patents

Abstract

The invention discloses a method for dry pressing and molding permanent magnetic ferrite, which comprises the following steps: (1) weighing a certain amount of permanent magnetic ferrite pre-sintering fine materials, and respectively adding 0.6% of lubricant and 0.6% -10% of binder according to the weight proportion; (2) and adding the prepared powder into a high-temperature mixer, stirring and mixing for 30 minutes, and uniformly mixing the powder. (3) Pressing the mixed material into a blank with the diameter phi of 40mm under the action of an oriented magnetic field, wherein the pressing pressure is more than or equal to 10Mpa, and the oriented magnetic field is more than or equal to 8000 Oe; (4) sintering the formed blank in a roller kiln; sintering temperature is 1180-1260 ℃, and heat preservation time is 90 minutes; (5) controlling the density of the blank to be 3.0-3.2 g/cm³The density after sintering is 4.8-5.2 g/cm³. The invention has the beneficial effects that: the lubricant calcium stearate is adopted, the binder is activated carbon binder, and the specific proportion is set, so that the bonding strength changes along with the temperature, and no harmful substance is discharged.

Description

Method for dry pressing and forming permanent magnetic ferrite

Technical Field

The invention relates to the field of permanent magnet oxidation, and mainly relates to a method for dry pressing permanent magnetic ferrite.

Background

At present, in the process of dry pressing and forming the permanent magnetic ferrite magnetic powder, a formed blank is required to have certain mechanical strength. The density is also required to be small and the magnetic particles in the product have good orientation during the forming process. In particular, during the production process, partial lubricant and binder are required to be added. The main role of lubrication is to reduce the frictional resistance between particles. The particles are oriented under the action of an orientation magnetic field, and the blank is convenient to demould. The main function of the binder is to increase the strength of the pressed blank. Enhancing the binding force between the particles. The blank is not cracked or chipped under the action of internal stress. The yield of the production is improved. The binder widely used in industry at present is mainly camphor powder. The camphor powder is easy to volatilize at normal temperature. A large amount of pungent odor is generated. Has certain harm to human body. From the viewpoint of environmental protection, improvement is required. Synthetic wax has also been used as a binder instead of camphor powder, but this method produces a large amount of dense smoke due to melting of paraffin wax in mass production, is harmful to the human body and the environment, and is not favorable for industrial production.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a method for dry pressing permanent magnetic ferrite.

The object of the present invention is achieved by the following technical means. A method for dry-pressing permanent magnetic ferrite, which comprises the following steps:

(1) weighing a certain amount of permanent magnetic ferrite pre-sintering fine materials, and respectively adding 0.6% of lubricant and 0.6% -10% of binder according to the weight proportion, wherein the lubricant is calcium stearate, and the binder is activated carbon binder;

(2) and adding the prepared powder into a high-temperature mixer, stirring and mixing for 30 minutes, and uniformly mixing the powder.

(3) Pressing the mixed material into a blank with the diameter phi of 40mm under the action of an oriented magnetic field, wherein the pressing pressure is more than or equal to 10Mpa, and the oriented magnetic field is more than or equal to 8000 Oe;

(4) sintering the formed blank in a roller kiln; sintering temperature is 1180-1260 ℃, and heat preservation time is 90 minutes;

(5) controlling the density of the blank to be 3.0-3.2 g/cm³The density after sintering is 4.8-5.2 g/cm³。

The particle size of the activated carbon binder is required to be less than or equal to 20 um.

The invention has the beneficial effects that: the lubricant calcium stearate is adopted, the binder is activated carbon binder, and the specific proportion is set, so that the bonding strength changes along with the temperature, and no harmful substance is discharged.

Detailed Description

The present invention will be described in detail with reference to the following examples:

the invention discloses a method for dry pressing and molding permanent magnetic ferrite, which comprises the following steps:

(1) weighing a certain amount of permanent magnetic ferrite pre-sintering fine materials, and respectively adding 0.6% of lubricant and 0.6% -10% of binder according to the weight proportion, wherein the lubricant is calcium stearate, the binder is activated carbon binder brofer-002, and the required granularity is less than or equal to 20 mu m.

(2) And adding the prepared powder into a high-temperature mixer, stirring and mixing for 30 minutes, and uniformly mixing the powder.

(3) Pressing the mixed material into a blank with the diameter phi of 40mm under the action of an oriented magnetic field, wherein the pressing pressure is more than or equal to 10Mpa, and the oriented magnetic field is more than or equal to 8000 Oe;

(4) sintering the formed blank in a roller kiln; sintering temperature is 1180-1260 ℃, and heat preservation time is 90 minutes;

(5) controlling the density of the blank to be 3.0-3.2 g/cm³The density after sintering is 4.8-5.2 g/cm³。

The optimal mixture ratio is as follows: 0.6% of lubricant and 2% of binder. The binder which is beneficial to environmental protection is very important for the production process of dry pressing permanent magnet oxidation. The Brfer-002 binder has better adhesion property at lower temperature. High adhesion strength, high temp (200 deg.C) and no generation of harmful substance. The heat distortion temperature is 79 ℃, and the bonding strength is highest. Facilitating tight bonding between the particles. Along with the temperature rise, the particle interior is gradually reduced, the binder is gradually melted off, and no harmful substance is discharged.

It should be understood that equivalent substitutions and changes to the technical solution and the inventive concept of the present invention should be made by those skilled in the art to the protection scope of the appended claims.

Claims (2)

1. A method for dry pressing permanent magnetic ferrite is characterized in that: the method comprises the following steps:

(1) weighing a certain amount of permanent magnetic ferrite pre-sintering fine materials, and respectively adding 0.6% of lubricant and 0.6% -10% of binder according to the weight proportion, wherein the lubricant is calcium stearate, and the binder is activated carbon binder;

(2) and adding the prepared powder into a high-temperature mixer, stirring and mixing for 30 minutes, and uniformly mixing the powder.

(3) Pressing the mixed material into a blank with the diameter phi of 40mm under the action of an oriented magnetic field, wherein the pressing pressure is more than or equal to 10Mpa, and the oriented magnetic field is more than or equal to 8000 Oe;

(4) sintering the formed blank in a roller kiln; sintering temperature is 1180-1260 ℃, and heat preservation time is 90 minutes;

(5) controlling the density of the blank to be 3.0-3.2 g/cm³The density after sintering is 4.8-5.2 g/cm³。

2. The method for dry-pressing permanent magnetic ferrite according to claim 1, characterized in that: the particle size of the activated carbon binder is required to be less than or equal to 20 um.