阅读说明：本技术 一种异方性粘结磁体及其制备方法 (Anisotropic bonded magnet and preparation method thereof ) 是由 罗阳 杨远飞 王子龙 于敦波 谢佳君 武凯文 廖一帆 贾际琛 于 2020-06-01 设计创作，主要内容包括：一种异方性粘结磁体及其制备方法,通过采用不同SmFeN含量和/或密度的磁体堆垛的方法,使其中间的磁体性能高、两端和/或外周的磁体性能低,从而补偿压制过程中由于密度差异产生的性能偏差,改善磁体轴向方向的性能均匀性。该方法解决了在取向密实化过程中会存在高度方向磁场取向以及密度不均匀的现象,以及出现中间低两边高的现象。由该方法制得的异方性粘结磁体,具有沿压制方向密度偏差小于2％的特点,有效提高了磁体的取向度和密度,以及磁体磁性能的均一性和尺寸精度。(A method for stacking magnets with different SmFeN contents and/or densities is adopted, so that the performance of the magnet in the middle is high, and the performance of the magnets at two ends and/or the periphery is low, thereby compensating the performance deviation generated by density difference in the pressing process and improving the performance uniformity of the magnets in the axial direction. The method solves the problems that the magnetic field orientation in the height direction and the density are not uniform in the orientation densification process, and the phenomena of low middle and high sides occur. The anisotropic bonded magnet prepared by the method has the characteristic that the density deviation along the pressing direction is less than 2 percent, and effectively improves the orientation degree and density of the magnet, the uniformity of the magnetic performance of the magnet and the dimensional accuracy.)

1. An anisotropic bonded magnet, comprising R-T-B-based permanent magnet powder and SmFeN permanent magnet powder,

wherein in the R-T-B permanent magnet powder, the content of R is 28-31 wt.%; the content of B is 0.9-1.1 wt.%, and the balance is T; r is selected from one or more rare earth elements, T is Fe or FeCo and transition group metal, B is boron;

the SmFeN permanent magnetic powder accounts for 5 to 30 percent of the weight content of the R-T-B permanent magnetic powder;

the anisotropic bonded magnet is formed by pressing a plurality of different preformed blanks, and the density deviation of the obtained anisotropic bonded magnet along the pressing direction is less than 2%.

2. An anisotropic bonded magnet according to claim 1, wherein the plurality of different preform bodies comprises preform bodies having different SmFeN permanent magnet powder contents.

3. An anisotropic bonded magnet according to claim 1 or 2, wherein R is 1 or 2 or more elements selected from Y, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu, preferably Nd or PrNd.

4. An anisotropic bonded magnet according to claim 1 or 2, wherein the bonded magnet is a bonded magnet ring, and the length-diameter ratio of the bonded magnet ring is greater than 0.6, preferably 1.0 to 10, and more preferably 2 to 8; the thickness is more than 1mm, preferably 1 to 20mm, and more preferably 1 to 5 mm.

5. An anisotropic bonded magnet according to claim 1 or 2, wherein the SmFeN permanent magnet powder has a particle size of 1 to 30 μm, preferably 3 to 10 μm.

6. A method for preparing an anisotropic bonded magnet is characterized by comprising the following steps:

step 1, preparing a bonding magnet raw material: the raw materials comprise R-T-B permanent magnet powder, SmFeN permanent magnet powder, thermosetting resin binder, coupling agent and lubricant; wherein, the weight content of the R-T-B permanent magnetic powder and the SmFeN permanent magnetic powder is 100 percent, and the SmFeN permanent magnetic powder is 3 to 40 percent of the weight content of the R-T-B permanent magnetic powder; the weight content of the binder is 1.0-6.0%, preferably 2.5-3.5% of that of the R-T-B permanent magnetic powder and the SmFeN permanent magnetic powder, the weight content of the coupling agent is 0.05-1.0%, preferably 0.1-0.3% of that of the R-T-B permanent magnetic powder and the SmFeN permanent magnetic powder, and the weight content of the lubricant is 0.05-2.0%, preferably 0.05-0.50% of that of the R-T-B permanent magnetic powder and the SmFeN permanent magnetic powder;

step 2, mixing rubber: uniformly mixing R-T-B permanent magnet powder and SmFeN permanent magnet powder in the raw materials with the thermosetting resin binder, the coupling agent and the lubricant to obtain composite magnetic powder;

step 3, room temperature preforming: putting the dried composite magnetic powder with different magnetic properties in a first mold and placing in a magnetic field H₁Respectively obtaining a plurality of different preformed blanks by medium-pressure forming, wherein the pressing pressure is 100-600 MPa, and the magnetic field H₁Less than 0.15T, and the pressing temperature is room temperature;

step 4, orientation molding of a warm pressing magnetic field: a plurality of different preformed blanks are stacked and placed in a second mould and placed in a magnetic field H₂Pressing and orienting at medium temperature, and pressing again; then demagnetizing, cooling and demoulding to obtain the anisotropic bonded magnet which is subjected to orientation molding by a warm-pressing magnetic field; wherein the magnetic field strength H₂0.6-3T, the pressing pressure is 300-1000 MPa, and the molding temperature is 60-200 ℃;

step 5, curing: heating the anisotropic bonded magnet subjected to orientation molding by the warm-pressing magnetic field to a certain temperature, and then carrying out heat preservation, wherein the heat preservation temperature is 100-200 ℃, and preferably 120-180 ℃; the heat preservation time is 0.5-2 hours.

7. The method of claim 6, wherein the step 2 comprises:

dissolving the coupling agent measured in the steps into a corresponding organic solvent, then uniformly mixing the coupling agent with R-T-B permanent magnet powder and SmFeN permanent magnet powder, and after the organic solvent is volatilized and removed, uniformly coating the coupling agent on the surface of the permanent magnet powder: and then dissolving the measured binder and lubricant in a corresponding organic solvent, uniformly mixing the binder and the lubricant with the R-T-B permanent magnetic powder and the SmFeN permanent magnetic powder coated with the coupling agent, and removing the organic solvent to obtain the composite magnetic powder required by preparing the bonded magnet.

8. The method of claim 6, wherein the plurality of different preform bodies includes a first preform body and a second preform body; the first preformed blank body is made of composite magnetic powder with low content of SmFeN permanent magnetic powder, and the second preformed blank body is made of composite magnetic powder with high content of SmFeN permanent magnetic powder; the composite magnetic powder with the lower SmFeN permanent magnetic powder content contains SmFeN 3-15 wt%, preferably 5-13 wt%, and the composite magnetic powder with the higher SmFeN permanent magnetic powder content contains SmFeN 15-40 wt%, preferably 15-30 wt%.

9. The method according to claim 8, wherein the density of the first preform body is less than the density of the second preform body, and the ratio of the densities of the first preform body and the second preform body is 1: 1.1-1: 1.5.

10. The method of claim 8 or 9, wherein in step 4, the placing of the plurality of different stacks of preform biscuits in a second mould comprises: the middle part is a second preformed blank body, the two ends are first preformed blank bodies, and the length of the middle second preformed blank body is smaller than that of the first preformed blank bodies at the two ends.

11. The method of claim 8 or 9, wherein in step 4, the placing of the plurality of different stacks of preform biscuits in a second mould comprises: the center is a second preformed blank body, and the periphery is a first preformed blank body.

12. The method of claim 6, wherein placing a number of different stacks of preform bodies in a second mold comprises: the density and/or SmFeN content of the preformed blanks arranged from the middle to the two ends are gradually reduced; or the density and/or the SmFeN content of the preformed blanks arranged from the center to the periphery are gradually reduced.

13. The method according to any one of claims 6 to 12, wherein in the step 4, a clearance ratio existing between the preformed blank and the warm-pressing magnetic field orientation forming die is 0.5 to 40%, preferably 3.5 to 25%.

14. The method as claimed in claim 11, wherein the first and second preformed blanks are magnetic cylinders or magnetic rings with the same shape, and the number ratio of the first and second preformed blanks is 1: 1-10: 1.

Technical Field

The invention relates to the technical field of bonded magnet materials, in particular to an anisotropic bonded magnet and a preparation method thereof.

Background

The bonded permanent magnet has good processing performance, large shape self-centering degree and high dimensional precision, is an indispensable important component of modern high and new technology products without secondary processing, and is widely applied to the fields of electronic information, computers, motors, automobiles and the like. The anisotropic bonded magnet has more excellent magnetic properties, and therefore, the size, efficiency, energy saving, and weight reduction of electronic products can be strongly promoted, and the anisotropic bonded magnet is a development direction of bonded permanent magnets.

The molding methods of the bonded permanent magnet include compression molding, calender molding, injection molding and extrusion molding, wherein the compression molded magnet is most widely used because of the highest magnetic performance.

The basic process flow of preparing the anisotropic bonded magnet by adopting thermosetting resin and compression molding is as follows:

mixing the magnetic powder with a binder and an additive to obtain composite magnetic powder → oriented pressing → demagnetization → curing → antiseptic treatment → performance detection, wherein the additive refers to a lubricant, a coupling agent and the like: the binder is generally a thermosetting resin such as an epoxy resin or a phenol resin. The orientation forming process can adopt three modes, namely room-temperature forming, warm-pressing forming and multi-step forming. The anisotropic bonded magnet prepared by room temperature forming has low density, poor orientation degree and lower magnetic performance. In the warm-pressing forming process, the high temperature softens the binder and melts the binder into a viscous state, and the low viscosity of the binder plays a certain role in lubrication, so that the purposes of reducing the rotation resistance of magnetic powder particles and the friction resistance between the magnetic powder and the mold wall during orientation are achieved, the orientation degree and the density of the magnet are further effectively improved, and the existing warm-pressing forming technology is widely applied to the preparation of anisotropic bonded magnets. Therefore, the improvement of the orientation degree and the density is the key for preparing the anisotropic bonded permanent magnet.

In the prior art, CN101599333A provides a method for manufacturing an anisotropic multi-pole magnetic ring by dry pressing, which comprises wet pulverizing magnetic powder, and adding more than one binder and lubricant into the dried magnetic powder; then pre-pressing and pre-magnetizing are carried out, then a high-speed pulverizer is adopted for mixing, and finally double-sided isobaric molding is carried out on the powder in a radial magnetic field.

CN101814368A provides a method for preparing anisotropic magnet: the particle size of the powder is adjusted, wherein the first mixture is composed of a first magnetic powder with a particle size of more than 20 μm and less than 150 μm, a thermosetting resin with an addition amount of less than 2.0 wt% in the anisotropic bonded magnet and a first additive, and the second mixture is composed of a second magnetic powder with a particle size of more than 1 μm and less than 20 μm and a second additive, and is used for improving the density and the magnetic performance of the magnet, but the difference between the magnetic field intensity of the central part of the magnet and the magnetic field intensity of the end part is more than 5%.

CN103489621A provides a method for preparing a die-pressed anisotropic bonded magnet, which adopts a two-step molding process, namely a room-temperature preforming and an orientation-densification warm-pressing molding process to prepare the anisotropic bonded magnet, and in the orientation-densification process, the phenomena of magnetic field orientation in the height direction and non-uniform density occur, and the phenomena of low middle and high sides occur.

CN107393709A provides a method for preparing a high-orientation-degree anisotropic bonded magnet by cold isostatic pressing, which comprises the steps of preparing a binder from thermosetting resin and a curing agent, adding anisotropic bonded magnetic powder into a binder solution, fully stirring, injecting into a silica gel mold, carrying out vacuum sealing, carrying out orientation under a 1.5T-2T magnetic field, and carrying out cold isostatic pressing to prepare the magnet.

In industrial production, for the magnetic ring with high length-diameter ratio, the existing technology of directly filling the magnetic powder form into the high-temperature magnetic field cavity can lead to the high-height of the magnetic powder in the cavity, easily causes the non-uniformity of the magnetic field orientation along the height direction, and in addition, the mixed magnetic powder is heated during the high-temperature filling, easily causes the magnetic powder to be adhered to the wall, is difficult to ensure the uniformity of the filling, and influences the uniformity and the size precision of the magnetic performance of the magnet.

Disclosure of Invention

The invention aims to solve the problem that the performance is uneven due to low middle density and high density at two ends or periphery in the axial direction in the preparation process of a high-length-diameter-ratio magnet, and adopts a method of stacking a plurality of magnets and mixing SmFeN powder into the magnets, wherein the content of the SmFeN powder in the middle is high, the content of the SmFeN powder at two ends or periphery is low, the performance deviation caused by density difference in the pressing process is compensated, and the performance uniformity in the axial direction of the magnets is improved.

In order to achieve the above purpose, the invention adopts the following scheme:

the invention provides an anisotropic bonded magnet, which comprises R-T-B permanent magnet powder and SmFeN permanent magnet powder,

wherein in the R-T-B permanent magnet powder, the content of R is 28-31 wt.%; the content of B is 0.9-1.1 wt.%, and the rest is T; r is selected from one or more rare earth elements, T is Fe or FeCo and transition group metal, B is boron;

the SmFeN permanent magnetic powder accounts for 3 to 40 percent of the weight content of the R-T-B permanent magnetic powder;

the anisotropic bonded magnet is formed by pressing a plurality of different preformed blanks, and the density deviation of the obtained anisotropic bonded magnet along the pressing direction is less than 2%.

Further, the plurality of different preformed blanks comprise preformed blanks with different content of SmFeN permanent magnetic powder.

Further, R is 1 or 2 or more elements selected from Y, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu, and is preferably Nd or PrNd.

Further, the bonded magnet is a bonded magnetic ring, the length-diameter ratio of the bonded magnetic ring is greater than 0.6, preferably 1.0-10, and further preferably 2-8; the thickness is more than 1mm, preferably 1 to 20mm, and more preferably 1 to 5 mm.

Furthermore, the particle size of the SmFeN permanent magnetic powder is 1-30 μm, and preferably 3-10 μm.

A second aspect of the present invention provides a method for producing an anisotropic bonded magnet, comprising the steps of:

step 1, preparing a bonding magnet raw material: the raw materials comprise R-T-B permanent magnet powder, SmFeN permanent magnet powder, thermosetting resin binder, coupling agent and lubricant; wherein, the weight content of the R-T-B permanent magnetic powder and the SmFeN permanent magnetic powder is 100 percent, and the SmFeN permanent magnetic powder is 3 to 40 percent of the weight content of the R-T-B permanent magnetic powder; the weight content of the binder is 1.0-6.0%, preferably 2.5-3.5% of that of the R-T-B permanent magnetic powder and the SmFeN permanent magnetic powder, the weight content of the coupling agent is 0.05-1.0%, preferably 0.1-0.3% of that of the R-T-B permanent magnetic powder and the SmFeN permanent magnetic powder, and the weight content of the lubricant is 0.05-2.0%, preferably 0.05-0.50% of that of the R-T-B permanent magnetic powder and the SmFeN permanent magnetic powder;

step 2, mixing rubber: uniformly mixing R-T-B permanent magnet powder and SmFeN permanent magnet powder in the raw materials with the thermosetting resin binder, the coupling agent and the lubricant to obtain composite magnetic powder;

step 3, room temperature preforming: putting the dried composite magnetic powder with different magnetic properties in a first mold and placing in a magnetic field H₁Respectively obtaining a plurality of different preformed blanks by medium-pressure forming, wherein the pressing pressure is 100-600 MPa, and the magnetic field H₁Less than 0.15T, and the pressing temperature is room temperature;

step 4, orientation molding of a warm pressing magnetic field: a plurality of different preformed blanks are stacked and placed in a second mould and placed in a magnetic field H₂Pressing and orienting at medium temperature, and pressing again; then demagnetizing, cooling and demoulding to obtain the anisotropic bonded magnet which is subjected to orientation molding by a warm-pressing magnetic field; wherein the magnetic field strength H₂0.6-3T, the pressing pressure is 300-1000 MPa, and the molding temperature is 60-200 ℃;

step 5, curing: heating the anisotropic bonded magnet subjected to orientation molding by the warm-pressing magnetic field to a certain temperature, and then carrying out heat preservation, wherein the heat preservation temperature is 100-200 ℃, and preferably 120-180 ℃; the heat preservation time is 0.5-2 hours.

Further, the step 2 comprises:

dissolving the coupling agent measured in the steps into a corresponding organic solvent, then uniformly mixing the coupling agent with R-T-B permanent magnet powder and SmFeN permanent magnet powder, and after the organic solvent is volatilized and removed, uniformly coating the coupling agent on the surface of the permanent magnet powder: and then dissolving the measured binder and lubricant in a corresponding organic solvent, uniformly mixing the binder and the lubricant with the R-T-B permanent magnetic powder and the SmFeN permanent magnetic powder coated with the coupling agent, and removing the organic solvent to obtain the composite magnetic powder required by preparing the bonded magnet.

Further, the plurality of different preform bodies includes a first preform body and a second preform body; the first preformed blank body is made of composite magnetic powder with low content of SmFeN permanent magnetic powder, and the second preformed blank body is made of composite magnetic powder with high content of SmFeN permanent magnetic powder; the composite magnetic powder with the lower SmFeN permanent magnetic powder content contains SmFeN 3-15 wt%, preferably 5-13 wt%, and the composite magnetic powder with the higher SmFeN permanent magnetic powder content contains SmFeN 15-40 wt%, preferably 15-30 wt%.

Furthermore, the density of the first preformed blank body is smaller than that of the second preformed blank body, and the ratio of the densities of the first preformed blank body and the second preformed blank body is 1: 1.1-1: 1.5.

Further, in step 4, the placing a plurality of different stacks of preform blanks into a second mold includes: the middle part is a second preformed blank body, the two ends are first preformed blank bodies, and the length of the middle second preformed blank body is smaller than that of the first preformed blank bodies at the two ends.

Further, in step 4, the placing a plurality of different stacks of preform blanks into a second mold includes: the center is a second preformed blank body, and the periphery is a first preformed blank body.

Further, the placing of the plurality of different stacks of preform blanks in the second mold comprises: the density and/or SmFeN content of the preformed blanks arranged from the middle to the two ends are gradually reduced; or the density and/or the SmFeN content of the preformed blanks arranged from the center to the periphery are gradually reduced.

Further, in the step 4, the clearance rate between the preformed blank and the warm-pressing magnetic field orientation forming die is 0.5-40%, and preferably 3.5-25%.

Further, the first pre-forming blank body and the second pre-forming blank body are magnetic cylinders or magnetic rings with the same shape, and the number ratio of the first pre-forming blank body to the second pre-forming blank body is 1: 1-10: 1.

In summary, the present invention provides an anisotropic bonded magnet and a method for manufacturing the same, in which a method of stacking magnets having different SmFeN contents and/or densities is used to make the magnet in the middle have high performance and the magnets at both ends and/or the periphery have low performance, thereby compensating the performance deviation caused by the density difference during the pressing process and improving the performance uniformity of the magnet in the axial direction. The method solves the problems that the magnetic field orientation in the height direction and the density are not uniform in the orientation densification process, and the phenomena of low middle and high sides occur. The anisotropic bonded magnet prepared by the method has the characteristic that the density deviation along the pressing direction is less than 2 percent, and effectively improves the orientation degree and density of the magnet, the uniformity of the magnetic performance of the magnet and the dimensional accuracy.

Drawings

Fig. 1 is a schematic flow chart of a method for producing an anisotropic bonded magnet according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.

A first aspect of the invention provides an anisotropic rare earth bonded magnet. The bonded magnet comprises R-T-B permanent magnet powder and SmFeN permanent magnet powder which are prepared by an HDDR method, wherein the content of R in the R-T-B permanent magnet powder is 28-31 wt%; the content of B is 0.9-1.1 wt.%, and the balance is T; r is selected from one or more rare earth elements, T is Fe or FeCo and a small amount of transition metal, and the content of the transition metal is below 3 percent; b is boron. The SmFeN permanent magnetic powder accounts for 5 to 30 percent of the weight content of the R-T-B permanent magnetic powder; the anisotropic bonded magnet is formed by pressing a plurality of different preformed blanks, and the density deviation of the obtained anisotropic bonded magnet along the pressing direction is less than 2%.

Further, the plurality of different preform bodies include preform bodies with different contents of SmFeN permanent magnet powder.

Further, 1 or 2 or more kinds of rare earth elements R selected from Y, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu can be used as the rare earth elements R constituting the R-T-B based permanent magnetic powder of the present invention, and Nd or PrNd is preferably used for reasons of cost and magnetic properties.

The element T constituting the R-T-B type rare earth magnet powder of the present invention is Fe or FeCo. The T amount of the average composition of the powder is the balance excluding other elements constituting the powder. In addition, the curie temperature can be increased by adding Co as an element for replacing Fe, too much results in a decrease in the residual magnetic flux density of the powder, and the residual magnetic flux density Br can be increased by adding a transition group element as an element for replacing Fe, but too much passivates the hydrogenation reaction in the HDDR process, affecting the magnetic properties.

Further, the shape of the bonded magnet may be varied, and the bonded magnet ring will be described below as an example, but is not limited to the bonded magnet ring. The density of the bonded magnetic ring determines the magnetic performance of the bonded magnetic ring, for the magnetic ring with the length-diameter ratio, the pressing process of the magnetic ring determines that the axial density has deviation, and the deviation of the density can cause the non-uniform magnetic performance of the magnetic ring in the axial direction, so that the output stability of the motor after the magnetic ring is assembled is influenced. The aspect ratio of the bonded magnet ring constituting the present invention is greater than 0.6, preferably 1.0 to 10, and more preferably 2 to 8, because the density deviation in the pressing direction is small for a magnet ring having a small aspect ratio (less than 0.6), which can be accomplished in the prior art. If the length-diameter ratio of the magnetic ring is too large (larger than 10), great difficulty is brought to the forming of the magnetic ring and the subsequent equipment process.

Furthermore, the wall thickness of the bonding magnetic ring is more than 1mm, preferably 1-20mm, and more preferably 1-5mm, if the wall thickness of the magnetic ring is too thin (less than 1mm), the difficulty of the preparation process of the magnetic ring is high, and the magnetic ring is easy to damage; if the wall thickness of the magnetic ring is too thick (more than 20mm), the combination strength is too weak because the radial pressing is not carried out, the integral forming of the magnetic ring is not facilitated when the wall thickness is too thick, and meanwhile, the trend that the wall thickness is too thick and the weight is not reduced is not met, so that the assembly process and the application field are limited.

Furthermore, the particle size of the SmFeN permanent magnetic powder is 1-30 μm, preferably 3-10 μm, if the particle size of the SmFeN permanent magnetic powder is too fine (less than 1 μm), the magnetic performance is obviously reduced, and meanwhile, the preparation difficulty is high and the SmFeN permanent magnetic powder is easy to oxidize; if the particle size of the SmFeN permanent magnetic powder is too coarse (> 30 μm), the voids between the NdFeB powders during pressing cannot be effectively filled, resulting in a low pressed density.

A second aspect of the present invention provides a method for producing an anisotropic bonded magnet, which is used for producing the anisotropic bonded magnet. The method adopts a two-step forming process, namely a method for preparing an anisotropic bonded magnetic ring (in the context of the invention, the anisotropic bonded magnet takes a magnetic ring as a specific embodiment, but is not limited to a magnetic ring structure) by room-temperature preforming and orientation warm-pressing forming, wherein a plurality of pre-pressed blank magnetic rings with different individual performances are prepared in the room-temperature preforming process, and a plurality of pre-pressed blank magnetic rings are adopted for stacking and pressing in the orientation warm-pressing forming process, wherein the middle magnetic ring has high performance and the two sides have low performance. Specifically, the method comprises the following processes as shown in fig. 1:

step 1, preparing a bonding magnetic ring raw material:

the raw materials of the bonded magnetic ring comprise R-T-B permanent magnetic powder, SmFeN permanent magnetic powder, thermosetting resin binder, coupling agent, lubricant and the like.

The rare earth element R constituting the R-T-B based permanent magnetic powder of the present invention may be 1 or 2 or more selected from Y, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu, and Nd or PrNd is preferably used for reasons of cost and magnetic properties. The element T constituting the R-T-B type rare earth magnet powder is Fe or FeCo; the thermosetting resin binder is epoxy resin, phenolic resin and other thermosetting resins; the coupling agent is silane coupling agent, titanate, etc. The lubricant is paraffin, stearate, silicon oil, etc.

The weight content of the SmFeN permanent magnetic powder is 3-40% of that of the R-T-B permanent magnetic powder, calculated by taking the weight content of the R-T-B permanent magnetic powder and the SmFeN permanent magnetic powder as 100; the weight content of the binder is 1.0-6.0% of that of the R-T-B permanent magnetic powder and the SmFeN permanent magnetic powder, preferably 2.5-3.5%; the weight content of the coupling agent is 0.05-1.0 percent of that of the R-T-B permanent magnetic powder and the SmFeN permanent magnetic powder, preferably 0.1-0.3 percent; the weight content of the lubricant is 0.05-2.0% of that of the R-T-B permanent magnetic powder and SmFeN permanent magnetic powder, preferably 0.05-0.50%.

Step 2, mixing rubber: and uniformly mixing the R-T-B permanent magnet powder and the SmFeN permanent magnet powder in the raw materials with the thermosetting resin binder, the coupling agent and the lubricant to obtain the composite magnetic powder.

Specifically, the coupling agent metered in the step is dissolved in a corresponding organic solvent, then is uniformly mixed with R-T-B permanent magnetic powder and SmFeN permanent magnetic powder, and after the organic solvent is volatilized and removed, the coupling agent is uniformly coated on the surface of the anisotropic magnetic powder: and then dissolving the metered binder and lubricant in corresponding solvents, uniformly mixing the binder and the R-T-B permanent magnetic powder coated with the coupling agent, and removing the organic solvent to obtain the composite magnetic powder for preparing the bonded magnet.

Various composite magnetic powder with different magnetic properties (different SmFeN contents) and/or densities are manufactured.

Step 3, room temperature preforming:

putting the dried various different composite magnetic powder into a die cavity and placing the die cavity in a magnetic field H₁Carrying out medium-pressure forming to obtain a plurality of different preformed blanks, wherein the pressing pressure is 100-600 MPa, and the magnetic field H is₁Less than 0.15T, and the forming temperature is room temperature;

the density of the preformed blank body is 3.6-5.0 g/cm³Since the strength of the preform decreases with decreasing density, when the density is less than 3.6g/cm³In the process, the strength of the preformed blank is low, and the preformed blank cannot be kept complete in the carrying process; when the density is higher than 5.0g/cm³In the process, high orientation degree is difficult to obtain in the subsequent orientation process of the warm-pressing magnetic field.

Specifically, the preformed compact is divided into two types, one type is composite magnetic powder with low content of SmFeN permanent magnetic powder, and the other type is composite magnetic powder with low content of SmFeN permanent magnetic powder, wherein the content of SmFeN in the composite magnetic powder with low content of SmFeN is 3% -15%, preferably 5-13%, and the content of SmFeN in the composite magnetic powder with high content is 15% -40%, preferably 15-30%.

Specifically, the preformed blanks are divided into two types, including a first preformed blank and a second preformed blank; the density of the first preformed blank body is smaller than that of the second preformed blank body, and the density ratio of the first preformed blank body to the second preformed blank body is 1: 1.1-1: 1.5.

Further, the first preformed blank body and the second preformed blank body are magnetic cylinders or magnetic rings with the same shape, and the number ratio of the first preformed blank body to the second preformed blank body is 1: 1-10: 1.

Step 4, orientation molding of a warm pressing magnetic field:

stacking a plurality of demolded different preformed blanks in another mold and placing the stack in a magnetic field H₂Pressing and orienting at medium temperature, wherein a blank with high performance is arranged in the middle, and blanks with low performance are arranged at two sides; or pressing again with a high-performance blank at the center and a low-performance blank at the periphery.Specifically, the density and/or SmFeN content of the preformed blanks arranged from the middle to the two ends are gradually reduced; or the density and/or the SmFeN content of the preformed blanks arranged from the center to the periphery are gradually reduced.

And in the stacking process of the preformed green bodies, the preformed green bodies are positioned in a mutual magnetic adsorption mode.

In the stacking process of the preforms, the length of the middle preform is smaller than that of the upper preform and the lower preform; in particular, the intermediate preform length is less than the length of the preforms at each end.

Wherein the magnetic field strength H₂The temperature of the pre-forming blank is 0.6-3T, the pressing pressure is 300-1000 MPa, the forming temperature is 60-200 ℃, the clearance rate is 0.5-40%, and the clearance between the pre-forming blank and the warm-pressing magnetic field orientation forming die is preferably 3.5% -25% in terms of two-step operation process and improvement of magnetic performance;

and then demagnetizing, cooling and demolding to obtain the anisotropic bonded magnetic ring, wherein the demagnetization mode adopts one of alternating current pulse demagnetization or reverse pulse demagnetization.

Step 5, curing:

the curing process comprises the following steps: heating the final-formed blank body to a certain temperature, and then carrying out heat preservation to further improve the strength of the bonded magnetic ring, wherein the heat preservation temperature is generally 100-200 ℃, and preferably 120-180 ℃; the heat preservation time is generally 0.5-2 hours, and can be properly adjusted according to the size of the magnetic ring.

The following description is given of specific examples of the present invention, but the present invention is by no means limited to the embodiments described.

Example 1

(1) Preparing the raw material of bonded magnetic ring

NdFeB anisotropic permanent magnet powder with the Nd content of 29.5 wt.%, SmFeN anisotropic permanent magnet powder, thermosetting resin binder epoxy resin, coupling agent silane and lubricant zinc stearate are prepared.

The SmFeN anisotropic permanent magnet powder comprises two batches with different contents, wherein the mass percentage of the SmFeN in the first batch is 9%, and the mass percentage of the SmFeN in the second batch is 23%, calculated by taking the weight content of the NdFeB anisotropic permanent magnet powder as 100%. Then, the total weight content of NdFeB and SmFeN anisotropic permanent magnetic powder is 100, and the weight content of the epoxy resin is 3 percent; the weight content of silane is 0.2%, and the weight content of zinc stearate is 0.25%.

(2) Mixed glue

Dissolving metered silane in acetone serving as an organic solvent, respectively placing the silane and the two batches of anisotropic permanent magnet powder with different SmFeN contents in a vacuum mixing stirrer, uniformly mixing, uniformly coating the silane on the surface of magnetic powder after the acetone is volatilized, respectively dissolving metered epoxy resin and zinc stearate in acetone, uniformly mixing the epoxy resin and the zinc stearate with the anisotropic permanent magnet powder coated with the silane, and preparing the composite magnetic powder for the two batches of bonded magnets with different properties after the acetone is volatilized.

(3) Room temperature preform

Drying the above two kinds of composite magnetic powder, placing in a mold cavity, and placing in a magnetic field H₁And (2) pressing and molding the blank under the condition of 0 to obtain different preformed blanks, wherein the pressing pressure is 350MPa, and the SmFeN content in the first preformed blank and the second preformed blank is 9 percent and 23 percent respectively.

The aspect ratio of the pressed magnet ring in this example is 1.25, the wall thickness is 2mm, and the number ratio of the first preformed body to the second preformed body is 2:1 according to the actual situation.

(4) Orientation molding by a warm pressing magnetic field:

stacking the above different preformed blanks in another mold, and placing in a magnetic field H₂(2.5T) medium-temperature pressing and orientation, wherein the pressing pressure is 700MPa, the molding temperature is 150 ℃, the clearance rate between the blank and the die cavity is 5 percent, the middle part is a second preformed blank with high performance and high density, the two sides are first preformed blanks with low performance and low density, the height of the first preformed blank is larger than that of the second preformed blank, and the blanks are positioned in a mutual magnetic adsorption mode for carrying out the warm-pressing orientation pressing and molding.

And then demagnetizing, cooling and demolding to obtain the anisotropic bonded magnetic ring.

(5) And (3) curing:

and heating the obtained final molded body to 160 ℃ for curing treatment, and preserving heat for 1 hour to finish the preparation of the anisotropic magnetic ring.

Example 2

(1) Preparing the raw material of bonded magnetic ring

NdFeB anisotropic permanent magnet powder with the Nd content of 29.5 wt.%, SmFeN anisotropic permanent magnet powder, thermosetting resin binder epoxy resin, coupling agent silane and lubricant zinc stearate are prepared.

The SmFeN anisotropic permanent magnet powder comprises two batches with different contents, wherein the mass percentage of the SmFeN in the first batch is 5%, and the mass percentage of the SmFeN in the second batch is 23%, calculated by taking the weight content of the NdFeB anisotropic permanent magnet powder as 100%. Then, the total weight content of NdFeB and SmFeN anisotropic permanent magnetic powder is 100, and the weight content of the epoxy resin is 3 percent; the weight content of silane is 0.2%, and the weight content of zinc stearate is 0.25%.

(2) Mixed glue

Dissolving metered silane in acetone serving as an organic solvent, respectively placing the silane and the two batches of anisotropic permanent magnet powder with different SmFeN contents in a vacuum mixing stirrer, uniformly mixing, uniformly coating the silane on the surface of magnetic powder after the acetone is volatilized, respectively dissolving metered epoxy resin and zinc stearate in acetone, uniformly mixing the epoxy resin and the zinc stearate with the anisotropic permanent magnet powder coated with the silane, and preparing the composite magnetic powder for the two batches of bonded magnets with different properties after the acetone is volatilized.

(3) Room temperature preform

Drying the above two kinds of composite magnetic powder, placing in a mold cavity, and placing in a magnetic field H₁And (2) pressing and molding the blank under the condition of 0 to obtain different preformed blanks, wherein the pressing pressure is 350MPa, and the SmFeN content in the first preformed blank and the second preformed blank is 5 percent and 23 percent respectively.

The aspect ratio of the pressed magnet ring in this example is 1.25, the wall thickness is 2mm, and the number ratio of the first preformed body to the second preformed body is 2:1 according to the actual situation.

Other procedures were the same as in example 1

Example 3

(1) Preparing the raw material of bonded magnetic ring

NdFeB anisotropic permanent magnet powder with the Nd content of 29.5 wt.%, SmFeN anisotropic permanent magnet powder, thermosetting resin binder epoxy resin, coupling agent silane and lubricant zinc stearate are prepared.

The SmFeN anisotropic permanent magnet powder comprises two batches with different contents, wherein the mass percentage of the SmFeN in the first batch is 15%, and the mass percentage of the SmFeN in the second batch is 23%, calculated by taking the weight content of the NdFeB anisotropic permanent magnet powder as 100%. Then, the weight content of the epoxy resin is 3 percent of the weight of the NdFeB anisotropic permanent magnetic powder, wherein the total weight content of the NdFeB anisotropic permanent magnetic powder and the SmFeN anisotropic permanent magnetic powder is 100 percent; the weight content of silane is 0.2 percent of the weight of the NdFeB anisotropic permanent magnetic powder, and the weight content of zinc stearate is 0.25 percent of the weight of the NdFeB anisotropic permanent magnetic powder.

(2) Mixed glue

Dissolving metered silane in acetone serving as an organic solvent, respectively placing the silane and the two batches of anisotropic permanent magnet powder with different SmFeN contents in a vacuum mixing stirrer, uniformly mixing, uniformly coating the silane on the surface of magnetic powder after the acetone is volatilized, respectively dissolving metered epoxy resin and zinc stearate in acetone, uniformly mixing the epoxy resin and the zinc stearate with the anisotropic permanent magnet powder coated with the silane, and preparing the composite magnetic powder for the two batches of bonded magnets with different properties after the acetone is volatilized.

(3) Room temperature preform

Drying the above two kinds of composite magnetic powder, placing in a mold cavity, and placing in a magnetic field H₁And (2) pressing and molding the blank under the condition of 0 to obtain different preformed blanks, wherein the pressing pressure is 350MPa, and the SmFeN content in the first preformed blank and the second preformed blank is 15% and 23% respectively.

The aspect ratio of the pressed magnet ring in this example is 1.25, the wall thickness is 2mm, and the number ratio of the first preformed body to the second preformed body is 2:1 according to the actual situation.

Other procedures were the same as in example 1

Example 4

(1) Preparing the raw material of bonded magnetic ring

NdFeB anisotropic permanent magnet powder with the Nd content of 29.5 wt.%, SmFeN anisotropic permanent magnet powder, thermosetting resin binder epoxy resin, coupling agent silane and lubricant zinc stearate are prepared.

The SmFeN anisotropic permanent magnet powder comprises two batches with different contents, wherein the mass percentage of the SmFeN in the first batch is 9%, and the mass percentage of the SmFeN in the second batch is 15%, calculated by taking the weight content of the NdFeB anisotropic permanent magnet powder as 100%. Then, the total weight content of NdFeB and SmFeN anisotropic permanent magnetic powder is 100, and the weight content of the epoxy resin is 3 percent; the weight content of silane is 0.2%, and the weight content of zinc stearate is 0.25%.

(2) Mixed glue

Dissolving metered silane in acetone serving as an organic solvent, respectively placing the silane and the two batches of anisotropic permanent magnet powder with different SmFeN contents in a vacuum mixing stirrer, uniformly mixing, uniformly coating the silane on the surface of magnetic powder after the acetone is volatilized, respectively dissolving metered epoxy resin and zinc stearate in acetone, uniformly mixing the epoxy resin and the zinc stearate with the anisotropic permanent magnet powder coated with the silane, and preparing the composite magnetic powder for the two batches of bonded magnets with different properties after the acetone is volatilized.

(3) Room temperature preform

Drying the above two kinds of composite magnetic powder, placing in a mold cavity, and placing in a magnetic field H₁And (2) pressing and molding the blank under the condition of 0 to obtain different preformed blanks, wherein the pressing pressure is 350MPa, and the SmFeN content in the first preformed blank and the second preformed blank is 9 percent and 15 percent respectively.

The aspect ratio of the pressed magnet ring in this example is 1.25, the wall thickness is 2mm, and the number ratio of the first preformed body to the second preformed body is 2:1 according to the actual situation.

Other procedures were the same as in example 1

Example 5

(4) Preparing the raw material of bonded magnetic ring

NdFeB anisotropic permanent magnet powder with the Nd content of 29.5 wt.%, SmFeN anisotropic permanent magnet powder, thermosetting resin binder epoxy resin, coupling agent silane and lubricant zinc stearate are prepared.

The SmFeN anisotropic permanent magnet powder comprises two batches with different contents, wherein the mass percentage of the SmFeN in the first batch is 9%, and the mass percentage of the SmFeN in the second batch is 25%, calculated by taking the weight content of the NdFeB anisotropic permanent magnet powder as 100%. Then, the total weight content of NdFeB and SmFeN anisotropic permanent magnetic powder is 100, and the weight content of the epoxy resin is 3 percent; the weight content of silane is 0.2%, and the weight content of zinc stearate is 0.25%.

(5) Mixed glue

Dissolving metered silane in acetone serving as an organic solvent, respectively placing the silane and the two batches of anisotropic permanent magnet powder with different SmFeN contents in a vacuum mixing stirrer, uniformly mixing, uniformly coating the silane on the surface of magnetic powder after the acetone is volatilized, respectively dissolving metered epoxy resin and zinc stearate in acetone, uniformly mixing the epoxy resin and the zinc stearate with the anisotropic permanent magnet powder coated with the silane, and preparing the composite magnetic powder for the two batches of bonded magnets with different properties after the acetone is volatilized.

(6) Room temperature preform

Drying the above two kinds of composite magnetic powder, placing in a mold cavity, and placing in a magnetic field H₁And (2) pressing and molding the blank under the condition of 0 to obtain different preformed blanks, wherein the pressing pressure is 350MPa, and the SmFeN content in the first preformed blank and the second preformed blank is 9 percent and 25 percent respectively.

The aspect ratio of the pressed magnet ring in this example is 1.25, the wall thickness is 2mm, and the number ratio of the first preformed body to the second preformed body is 2:1 according to the actual situation.

Other procedures were the same as in example 1

Example 6

(1) Preparing the raw material of bonded magnetic ring

NdFeB anisotropic permanent magnet powder with the Nd content of 29.5 wt.%, SmFeN anisotropic permanent magnet powder, thermosetting resin binder epoxy resin, coupling agent silane and lubricant zinc stearate are prepared.

The SmFeN anisotropic permanent magnet powder comprises two batches with different contents, wherein the mass percentage of the SmFeN in the first batch is 9%, and the mass percentage of the SmFeN in the second batch is 23%, calculated by taking the weight content of the NdFeB anisotropic permanent magnet powder as 100%. Then, the total weight content of NdFeB and SmFeN anisotropic permanent magnetic powder is 100, and the weight content of the epoxy resin is 1 percent; the weight content of silane is 0.2%, and the weight content of zinc stearate is 0.25%.

Other procedures were the same as in example 1

Example 7

(2) Preparing the raw material of bonded magnetic ring

NdFeB anisotropic permanent magnet powder with the Nd content of 29.5 wt.%, SmFeN anisotropic permanent magnet powder, thermosetting resin binder epoxy resin, coupling agent silane and lubricant zinc stearate are prepared.

The SmFeN anisotropic permanent magnet powder comprises two batches with different contents, wherein the mass percentage of the SmFeN in the first batch is 9%, and the mass percentage of the SmFeN in the second batch is 23%, calculated by taking the weight content of the NdFeB anisotropic permanent magnet powder as 100%. Then, the total weight content of NdFeB and SmFeN anisotropic permanent magnetic powder is 100, and the weight content of the epoxy resin is 5 percent; the weight content of silane is 0.2%, and the weight content of zinc stearate is 0.25%.

Other procedures were the same as in example 1

Example 8

(1) Preparing the raw material of bonded magnetic ring

NdFeB anisotropic permanent magnet powder with the Nd content of 29.5 wt.%, SmFeN anisotropic permanent magnet powder, thermosetting resin binder epoxy resin, coupling agent silane and lubricant zinc stearate are prepared.

The SmFeN anisotropic permanent magnet powder comprises two batches with different contents, wherein the mass percentage of the SmFeN in the first batch is 9%, and the mass percentage of the SmFeN in the second batch is 23%, calculated by taking the weight content of the NdFeB anisotropic permanent magnet powder as 100%. Then, the total weight content of the NdFeB and SmFeN anisotropic permanent magnetic powder is 100, and the weight content of the epoxy resin is 3%; the weight content of silane is 0.2%, and the weight content of zinc stearate is 0.25%.

(2) Mixed glue

Dissolving metered silane in acetone serving as an organic solvent, respectively placing the silane and the two batches of anisotropic permanent magnet powder with different SmFeN contents in a vacuum mixing stirrer, uniformly mixing, uniformly coating the silane on the surface of magnetic powder after the acetone is volatilized, respectively dissolving metered epoxy resin and zinc stearate in acetone, uniformly mixing the epoxy resin and the zinc stearate with the anisotropic permanent magnet powder coated with the silane, and preparing the composite magnetic powder for the two batches of bonded magnets with different properties after the acetone is volatilized.

(3) Room temperature preform

Drying the above two kinds of composite magnetic powder, placing in a mold cavity, and placing in a magnetic field H₁And (2) pressing and molding the blank under the condition of 0 to obtain different preformed blanks, wherein the pressing pressure is 350MPa, and the SmFeN content in the first preformed blank and the second preformed blank is 9 percent and 23 percent respectively.

The aspect ratio of the pressed magnet ring in this example is 1.25, the wall thickness is 2mm, and the number ratio of the first preformed body to the second preformed body is 2:1 according to the actual situation.

(4) Orientation molding by a warm pressing magnetic field:

stacking the above different preformed blanks in another mold, and placing in a magnetic field H₂(2.5T) medium-temperature pressing and orientation, wherein the pressing pressure is 700MPa, the molding temperature is 150 ℃, the clearance rate between the blank and the die cavity is 5 percent, the middle part is a second preformed blank with high performance and high density, the two sides are first preformed blanks with low performance and low density, the height of the first preformed blank is larger than that of the second preformed blank, and the blanks are positioned in a mutual magnetic adsorption mode for carrying out the warm-pressing orientation pressing and molding.

And then demagnetizing, cooling and demolding to obtain the anisotropic bonded magnetic ring.

(5) And (3) curing:

and heating the obtained final molded body to 120 ℃ for curing treatment, and preserving heat for 1 hour to finish the preparation of the anisotropic magnetic ring.

Other procedures were the same as in example 1

Example 9

(1) Preparing the raw material of bonded magnetic ring

NdFeB anisotropic permanent magnet powder with the Nd content of 29.5 wt.%, SmFeN anisotropic permanent magnet powder, thermosetting resin binder epoxy resin, coupling agent silane and lubricant zinc stearate are prepared.

The SmFeN anisotropic permanent magnet powder comprises two batches with different contents, wherein the mass percentage of the SmFeN in the first batch is 9%, and the mass percentage of the SmFeN in the second batch is 23%, calculated by taking the weight content of the NdFeB anisotropic permanent magnet powder as 100%. Then, the total weight content of NdFeB and SmFeN anisotropic permanent magnetic powder is 100, and the weight content of the epoxy resin is 3 percent; the weight content of silane is 0.2%, and the weight content of zinc stearate is 0.25%.

(2) Mixed glue

Dissolving metered silane in acetone serving as an organic solvent, respectively placing the silane and the two batches of anisotropic permanent magnet powder with different SmFeN contents in a vacuum mixing stirrer, uniformly mixing, uniformly coating the silane on the surface of magnetic powder after the acetone is volatilized, respectively dissolving metered epoxy resin and zinc stearate in acetone, uniformly mixing the epoxy resin and the zinc stearate with the anisotropic permanent magnet powder coated with the silane, and preparing the composite magnetic powder for the two batches of bonded magnets with different properties after the acetone is volatilized.

(3) Room temperature preform

Drying the above two kinds of composite magnetic powder, placing in a mold cavity, and placing in a magnetic field H₁And (2) pressing and molding the blank under the condition of 0 to obtain different preformed blanks, wherein the pressing pressure is 350MPa, and the SmFeN content in the first preformed blank and the second preformed blank is 5 percent and 13 percent respectively.

The aspect ratio of the pressed magnet ring in this example is 1.25, the wall thickness is 2mm, and the number ratio of the first preformed body to the second preformed body is 2:1 according to the actual situation.

(4) Orientation molding by a warm pressing magnetic field:

stacking the above different preformed blanks in another mold, and placing in a magnetic field H₂(2.5T) medium-temperature pressing and forming orientation, wherein the pressing pressure is 700MPa, the forming temperature is 150 ℃, and the clearance rate between the blank and the die cavity is 5 percent, whereinThe middle is a second preformed blank body with high performance and higher density, the two sides are first preformed blank bodies with lower performance and lower density, the height of the first preformed blank bodies is larger than that of the second preformed blank bodies, and the blank bodies are positioned in a mutual magnetic adsorption mode to be subjected to warm pressing orientation pressing forming.

And then demagnetizing, cooling and demolding to obtain the anisotropic bonded magnetic ring.

(5) And (3) curing:

and heating the obtained final molded body to 180 ℃ for curing treatment, and preserving heat for 1 hour to finish the preparation of the anisotropic magnetic ring.

Other procedures were the same as in example 1

Comparative example 1

(1) Preparing the raw material of bonded magnetic ring

NdFeB anisotropic permanent magnet powder with the Nd content of 29.5 wt.%, SmFeN anisotropic permanent magnet powder, thermosetting resin binder epoxy resin, coupling agent silane and lubricant zinc stearate are prepared.

The mass percentage of SmFeN is 3 percent based on the weight content of the NdFeB anisotropic permanent magnetic powder as 100 percent. Then, the total weight content of NdFeB and SmFeN anisotropic permanent magnetic powder is 100, and the weight content of the epoxy resin is 3 percent; the weight content of silane is 0.2%, and the weight content of zinc stearate is 0.25%.

(2) Mixed glue

Dissolving metered silane in acetone serving as an organic solvent, respectively placing the silane and the two batches of anisotropic permanent magnet powder with different SmFeN contents in a vacuum mixing stirrer, uniformly mixing, uniformly coating the silane on the surface of magnetic powder after the acetone is volatilized, respectively dissolving metered epoxy resin and zinc stearate in acetone, uniformly mixing the epoxy resin and the zinc stearate with the anisotropic permanent magnet powder coated with the silane, and preparing the composite magnetic powder for the two batches of bonded magnets with different properties after the acetone is volatilized.

(3) Room temperature preform

Drying the above two kinds of composite magnetic powder, placing in a mold cavity, and placing in a magnetic field H₁Pressing and molding the mixture in a pressure range of 0 ℃ to obtain a preformed body, wherein the pressing pressure isThe pressure is 350MPa, and the content of SmFeN in the preformed blank is 5 percent.

The aspect ratio of the pressed magnet ring in this example is 1.25, the wall thickness is 2mm, and the number ratio of the first preformed body to the second preformed body is 2:1 according to the actual situation.

Other procedures were the same as in example 1

Comparative example 2

(4) Preparing the raw material of bonded magnetic ring

NdFeB anisotropic permanent magnet powder with the Nd content of 29.5 wt.%, SmFeN anisotropic permanent magnet powder, thermosetting resin binder epoxy resin, coupling agent silane and lubricant zinc stearate are prepared.

The mass percentage of SmFeN is 40 percent based on the weight content of the NdFeB anisotropic permanent magnetic powder as 100 percent. Then, the total weight content of NdFeB and SmFeN anisotropic permanent magnetic powder is 100, and the weight content of the epoxy resin is 3 percent; the weight content of silane is 0.2%, and the weight content of zinc stearate is 0.25%.

(5) Mixed glue

Dissolving metered silane in acetone serving as an organic solvent, respectively placing the silane and the two batches of anisotropic permanent magnet powder with different SmFeN contents in a vacuum mixing stirrer, uniformly mixing, uniformly coating the silane on the surface of magnetic powder after the acetone is volatilized, respectively dissolving metered epoxy resin and zinc stearate in acetone, uniformly mixing the epoxy resin and the zinc stearate with the anisotropic permanent magnet powder coated with the silane, and preparing the composite magnetic powder for the two batches of bonded magnets with different properties after the acetone is volatilized.

(6) Room temperature preform

Drying the above two kinds of composite magnetic powder, placing in a mold cavity, and placing in a magnetic field H₁And (2) pressing and molding the mixture in the pressure range of 0 to obtain a preformed body, wherein the pressing pressure is 350MPa, and the content of SmFeN in the preformed body is 13%.

The aspect ratio of the pressed magnet ring in this example is 1.25, the wall thickness is 2mm, and the number ratio of the first preformed body to the second preformed body is 2:1 according to the actual situation.

Other procedures were the same as in example 1

After the prepared magnetic ring is magnetized, surface magnetic distribution and radial crushing force of the upper end, the middle end and the lower end are tested, then the magnetic ring is cut into 3 sections, density and performance data of the two ends and the middle are obtained, and uniformity of the density and performance along the axial direction is evaluated. As shown in table 1.

TABLE 1

In summary, the present invention provides an anisotropic bonded magnet and a method for manufacturing the same, in which a method of stacking magnets having different SmFeN contents and/or densities is used to make the magnet in the middle have high performance and the magnets at both ends and/or the periphery have low performance, thereby compensating the performance deviation caused by the density difference during the pressing process and improving the performance uniformity of the magnet in the axial direction. The method solves the problems that the magnetic field orientation in the height direction and the density are not uniform in the orientation densification process, and the phenomena of low middle and high sides occur. The anisotropic bonded magnet prepared by the method has the characteristic that the density deviation along the pressing direction is less than 2 percent, and effectively improves the orientation degree and density of the magnet, the uniformity of the magnetic performance of the magnet and the dimensional accuracy.

It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.