CN212230241U - Forming die of annular sintered neodymium iron boron magnet - Google Patents
Forming die of annular sintered neodymium iron boron magnet Download PDFInfo
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- CN212230241U CN212230241U CN202021491072.8U CN202021491072U CN212230241U CN 212230241 U CN212230241 U CN 212230241U CN 202021491072 U CN202021491072 U CN 202021491072U CN 212230241 U CN212230241 U CN 212230241U
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Abstract
The utility model provides a forming die of ring form sintered neodymium iron boron magnetism body. Forming die includes the major part, go up the pressure head, the pressure head down, the die cavity, wherein the major part includes two relative non-magnetic conduction curb plates, two relative magnetic conduction curb plates, in the space that forms between two non-magnetic conduction curb plates and two magnetic conduction curb plates, the pressure head is located the bottom in space down, it is located the top in space to go up the pressure head, the die cavity is located between pressure head and the pressure head down, place flexible cylinder core in the die cavity, during the preparation, after the neodymium iron boron magnetic powder of putting loose device state is built-in to the die cavity, place flexible cylinder core in the die cavity, suppress through forming die and obtain the magnet finished product. The utility model has the advantages of, adopt this method and this type core structure's device production ring sintering neodymium iron boron can increase substantially material utilization and product percent of pass.
Description
Technical Field
The utility model relates to a sintered neodymium iron boron's manufacturing field, specific is a forming die of ring form sintered neodymium iron boron magnetism body.
Background
Compared with the traditional permanent magnet material, the sintered Nd-Fe-B permanent magnet material has wide application in the world due to high magnetic energy product, and the product relates to the fields of wind power generation, compressors, sound and electricity parts, new energy automobiles and the like. The product shape includes square, tile, cylinder, ring, irregular shape, etc. according to different use conditions. However, while the sintered nd-fe-b is widely applied, there are certain problems: the higher the complexity of the product shape, the higher the manufacturing cost, such as machining cost, of the sintered nd-fe-b magnet.
Taking a circular sintered neodymium iron boron magnet as an example, the conventional production process at present is to press a square green body under the condition of a vertical or parallel magnetic field, and then to perform sintering densification and aging treatment to obtain a blank semi-finished product. In the subsequent machining process, the periphery of the part is subjected to wire cutting and blanking to form the outer diameter of the circular product, and then internal ring wire cutting, grinding or hollowing (drilling) is performed to form the inner diameter of the circular product. In a comprehensive view, the outer diameter and the inner diameter are processed in the processing process of a finished product, so that the complexity of machining procedures is increased, huge material waste is caused, and the comprehensive material utilization rate of the product is even less than 60%. Even by improving the processing technique, it is difficult to fundamentally improve the material utilization, for example, in the method for producing a ring magnet disclosed in patent No. CN101728041B, the sintered blank is processed into a ring body by using an improved processing procedure, and although the material is saved from the aspect of processing, the material loss of the inner arc cannot be avoided.
The improved production method is characterized by that in the green body production stage, the cylindrical green body can be directly produced by adopting semicircular upper and lower pressure heads, and the green body is undergone the process of isostatic pressing, before sintering, the mould core can be taken out, and then the semi-finished product of cylindrical blank can be obtained by means of sintering ageing process. In the subsequent machining process, the outer diameter of the circular ring product can be obtained only by a small amount of grinding without cutting the outer periphery of the part. The inner diameter of the annular product is then formed by similar processing as previously described. The production process obviously improves the material utilization rate due to the reduction of the material waste of the peripheral outline, and the material utilization rate can be improved to 60-70% under the same product size condition, but the utilization rate is still low due to the material loss of the inner arc.
In a further improved production method, for example, the technology disclosed in patent No. CN203124733U and the production method of the ring magnet disclosed in patent No. CN102528029A, in the stage of green body manufacturing, a mold capable of directly producing the ring-shaped neodymium iron boron magnet is provided, a semicircular upper and lower pressing heads are adopted, and a columnar mold core is configured, after molding, the ring-shaped green body is formed, and a large amount of inner holes are not required to be cut on the sintered magnet blank, so that the production efficiency and the material utilization rate can be improved. However, such a technique has problems that the core of the mold is not easily removed, the integrity of the inner surface of the ring blank is destroyed, and the number of steps is increased. In addition, because the inner hole of the green body is not easy to be heated, the poor sintering shrinkage of the ring and the cracking of the magnet are easily caused.
Still further improved production method, for example the technology disclosed in patent No. CN204584268U, designs an isostatic pressing structure suitable for circular neodymium iron boron magnet, uses rubber, nylon, plastic or metal as the mold core, and adds a diaphragm structure between the mold core and the inner hole of the green body, so that the process of removing the mold core from the green body after isostatic pressing is easier, and the surface of the inner hole of the green body is not damaged. However, as described above, according to this technique, since the core needs to be removed before sintering, there is also a problem that it takes a lot of time, the inner hole of the green compact is not easily heated, sintering shrinkage of the ring is likely to be poor, and the magnet is likely to crack.
A further improved method of manufacturing, for example, the CN204686013U patent discloses an improved annular neodymium iron boron sintering boat, the inside of which has quartz sand or corundum material, the sintering boat is an integral structure of a main body and a middle cylindrical core, and the diameter of the core is smaller than the inner diameter of the sintered magnet. This technique improves the sintering heat pattern of the ring magnet and simultaneously reduces the rate of magnet cracking during sintering shrinkage of the green compact, but inevitably requires the internal core of the ring green compact to be removed beforehand before the green compact is placed in the sintering boat. Therefore, the green compact may be damaged by the same time and labor.
SUMMERY OF THE UTILITY MODEL
The utility model discloses the technical problem that will solve is: the forming die for the circular sintered neodymium-iron-boron magnet is high in material utilization rate, easy to process and not prone to cracking during sintering.
The annular sintered neodymium iron boron magnet ring has wide market application and different magnetic properties and sizes. However, such products have in common that they do not avoid the separate machining of the inner bore during the manufacturing process from the blank to the finished product. The inner hole material can be recycled only according to waste materials after being processed, which leads to low material utilization rate of the annular product. Moreover, the larger the ratio of the inner hole circular ring radius is, the more serious the material waste is.
Although the prior art introduces a process for directly producing the annular blank, which can improve the material utilization rate, the production difficulty of the annular blank is high, and the blank is easy to sinter and crack. The reason for this is that the external portion is heated rapidly and the internal portion is heated slowly during sintering, and the sintering shrinkage rates of the internal and external portions of the green compact are not uniform, resulting in cracking.
In view of this, the present invention adopts the following technical solutions to solve the above main problems.
The technical proposal of the utility model is to provide a forming die of a circular ring shaped sintered neodymium iron boron magnet, which is characterized in that,
including main part upper pressure head, lower pressure head, die cavity, wherein main part includes two relative non-magnetic conduction curb plates, two relative magnetic conduction curb plates, in the space that forms between two non-magnetic conduction curb plates and two magnetic conduction curb plates, lower pressure head is located the bottom in space, and upper pressure head is located the top in space, and the die cavity is located between upper pressure head and the lower pressure head, places flexible cylinder core in the die cavity.
Preferably, after the neodymium iron boron magnetic powder in a loose state is placed in the die cavity, the flexible cylindrical core is placed in the die cavity, and the axial direction of the flexible cylindrical core is in the horizontal direction and is parallel to the magnetic field direction between the two magnetic conduction side plates.
Preferably, the length W of the flexible cylindrical core is consistent with the distance between the inner walls of the two magnetically conductive side plates, and the radius R of the flexible cylindrical core is less than half of the distance between the two magnetically non-conductive side plates.
Preferably, the radius R of the flexible cylindrical core is more than 2mm and less than 5 mm.
Preferably, the lower pressure head is fixedly or movably connected to the bottom of a space formed between the two non-magnetic-conductive side plates and the two magnetic-conductive side plates, the lower pressure head moves back and forth in the space when the lower pressure head is movably connected, the upper pressure head is movably connected to the top of the space between the two non-magnetic-conductive side plates and the two magnetic-conductive side plates, and the upper pressure head moves back and forth in the space.
Utilize the forming die of the ring form sintered neodymium iron boron magnet that this application provided to prepare ring form sintered neodymium iron boron magnet, its preparation step includes:
a. preparing materials: preparing a flexible cylindrical core, wherein the radius of the flexible cylindrical core is R, and the length of the flexible cylindrical core is W; preparing sintered neodymium iron boron magnetic powder with the same weight according to the required weight of the neodymium iron boron blank;
b. placing materials: placing the neodymium iron boron magnetic powder into a forming die in a loose state, wherein the loose height of the neodymium iron boron magnetic powder is L; the flexible cylindrical core is placed in the magnetic powder in a loose state and is positioned at the L/2 position of the loose height of the flexible cylindrical core, and the axial direction of the flexible cylindrical core 4 is in the horizontal direction and is parallel to the direction of the magnetic field;
c. preparing a green body: applying vertical pressure to neodymium iron boron magnetic powder with a flexible cylindrical core in a forming die to obtain a circular ring green body assembly with the flexible cylindrical core embedded inside;
d. isostatic pressing treatment: after packaging and isolating the ring green body assembly, placing the ring green body assembly into liquid isostatic pressing, and applying isostatic pressing to obtain a ring green body assembly with higher density;
e. sintering and aging treatment: placing the ring green body assembly into a sintering furnace for vacuum sintering to obtain a ring sintered blank, and dispersing the flexible cylindrical core under the action of high temperature to separate from the ring sintered blank; placing the sintered and molded circular ring blank into an aging furnace for aging to obtain an aged circular ring blank;
f. respectively carrying out outer arc grinding processing and inner arc grinding processing, end face flat grinding processing and subsequent slicing processing on the circular ring blank to obtain a machined semi-finished product; and (4) carrying out surface treatment on the machined semi-finished product to obtain a circular neodymium iron boron finished product.
The main material of the flexible cylindrical core is alumina or zirconia powder or a mixture of the alumina powder and the zirconia powder, and the flexible cylindrical core is made by adopting jelly bonding.
The preparation process of the flexible cylindrical core mainly comprises the steps of mixing polyethylene glycol powder and purified water according to the part ratio of 70-90%, decocting water and polyethylene glycol to obtain polyethylene glycol glue, wherein the decocting process can adopt a glass cup or a stainless steel cup, the lower part of the glass cup or the stainless steel cup is heated by an electric furnace or an alcohol furnace, and stirring is carried out continuously in the heating process; mixing polyethylene glycol glue and alumina or zirconia powder according to a proportion, wherein the preferred proportion is that the weight proportion of alumina or zirconia is 50-90%, and preparing the mixture into a semisolid.
Placing the semi-solid mixture in a cylindrical mold made of rubber material, and carrying out isostatic pressing after vacuum packaging; and drying the isostatic compaction body at the temperature of 80-150 ℃ for 2-10 hours, improving the hardness, and removing water to obtain the final flexible cylindrical core.
The diameter R of the flexible cylindrical core is preferably set to be between 2mm and 5mm, if R is too small, for example, R is smaller than 2mm, the core is difficult to manufacture and easy to break, and if R is too large, for example, R is larger than 5mm, when the flexible cylindrical core is formed, the core shrinks too much under pressure, so that green bodies are seriously deformed, and the yield is low.
Compared with the prior art, the utility model discloses an useful part lies in:
the forming die used in the preparation process is provided with the flexible cylindrical core, so that the inner arc part of the circular ring magnet is replaced, the material is saved, and the subsequent processing does not need to drill or empty again. The strength of the flexible cylindrical core is much lower than that of the pressed neodymium iron boron green body, and the flexible cylindrical core is relatively soft and relatively low in density. Flexible cylinder core face plays a role in the aspect of reducing the crackle incidence, because during the sintering, inside heat can transmit the neodymium iron boron unburned bricks through this core, makes the interior cambered surface of neodymium iron boron unburned bricks also heat up simultaneously, has reduced the difference in temperature of intrados and extrados, and then has reduced the shrinkage factor difference, is difficult to lead to the crackle to appear. Meanwhile, as the flexible cylindrical core is of a bonding mixed structure and has lower strength than a sintered green body, under the dual actions of heating the flexible cylindrical core and shrinking the green body wrapped outside the flexible cylindrical core, the polyethylene glycol starts to decompose at high temperature, is degassed and discharged along with organic matters such as lubricant in the green body, and simultaneously the flexible cylindrical core starts to soften and shrink without taking out the flexible cylindrical core. The utility model discloses utilize the ring neodymium iron boron magnetism body of flexible cylinder core preparation to obtain obviously improving on the qualification rate of sintering article, the utilization ratio of neodymium iron boron magnetic material.
Drawings
Fig. 1 is a schematic structural diagram of the forming device of the present invention.
Fig. 2 is a schematic structural diagram of the forming device of the present invention.
Description of the labeling: 1. the magnetic-conductive type neodymium-iron-boron magnetic core forming machine comprises an upper pressure head, 2 non-magnetic side plates, 3 a die cavity and neodymium-iron-boron powder loosely filled in the die cavity, 4 a flexible circular core, 5 a lower pressure head, 6 a magnetic-conductive side plate, L and the loose height of the neodymium-iron-boron powder, R and the radius of the flexible circular core, W and the length of the flexible circular core, and H and the direction of a horizontal magnetic field.
Detailed Description
The invention is further described below with reference to specific embodiments, which are provided only for the purpose of illustration and are not intended to be limiting in any way.
The utility model discloses preparation method of ring sintering neodymium iron boron magnetism body, the preparation flow of magnet, include and make neodymium iron boron thin slice alloy according to the thin technology of taking of rapid hardening, pass through hydrogen treatment with neodymium iron boron thin slice alloy, the air current grinds the preface and makes sintering neodymium iron boron powder, with the powder first time shaping under pressure effect and parallel magnetic field condition, with the forming body under the isostatic pressing condition of liquid, carry out the secondary forming, carry out vacuum sintering densification in the vacuum sintering stove, carry out heat treatment in ageing heat treatment furnace, obtain the blank.
The processes of rapid hardening and thin strip, hydrogen treatment and gas milling of the preparation process adopt the currently known or well-known technology. The neodymium iron boron powder has a composition referred to the trade mark of commercially available general sintered neodymium iron boron, for example, the basic composition thereof may be set to ReaT(1-a-b-c)BbMCWherein, a, B and c are expressed in percentage by mass of each element in the component proportion, Re is a rare earth element and comes from at least one of Pr, Nd, Dy, Tb, Ho and Gd, T is at least one of Fe or Co, B is an element B, M is at least one of Al, Cu, Ga, Ti, Zr, Nb, MO and V, and the specific content is that a is more than or equal to 27 percent and less than or equal to 33 percent, B is more than or equal to 0.85 percent and less than or equal to 1.3 percent and c is less than or equal to 5 percent.
The utility model discloses the preparation method of ring sintering neodymium iron boron magnetism body after obtaining the blank, drops into machining process with the blank, and the processing equipment of adoption includes present general flat grinding machine, excircle centerless grinding machine, internal grinder, inside diameter slicer etc.. The processing flow comprises a, flat grinding and light exposure of the end face of the blank, b, processing of an outer arc by a centerless grinder, c, processing of an inner arc by an inner grinder and d, slicing by an inner slicer.
The utility model discloses forming die of ring sintering neodymium iron boron magnetism body, this forming die's flexible cylinder core's powder material purchase and commercially available alumina powder or zirconia powder, its granularity is preferably 0.5-2mm, and the adhesive adopts commercially available polyethylene glycol granule, for example PEG-600.
The reason that the polyethylene glycol is adopted for manufacturing the flexible cylindrical core is that the polyethylene glycol is an organism which is high in viscosity and easy to dissolve in water, and high-viscosity glue can be prepared by utilizing the viscosity of the polyethylene glycol. After the semi-solid mixture is prepared by the alumina powder, the bonding is firm, the moisture content is low, and the deformation is small during drying.
In the preparation of the flexible cylindrical core, the preferable proportion is that the weight proportion of alumina or zirconia is 50-90%, and the flexible cylindrical core is prepared into a semisolid; when the proportion of alumina or zirconia is higher than 90%, the bonding is not firm and the dispersion is easy.
During molding, the flexible cylindrical core is placed in the neodymium iron boron powder in the horizontal direction, and the placing depth is optimal in a position which is half of the loose height of the powder. Because the molding magnetic field of the mold cavity is horizontal, the flexible cylindrical core is positioned at the center of the green body after being pressed and embedded into the green body under the pressure of the molding press. When the green body undergoes sintering shrinkage, the radial direction thereof is shrunk in an equal proportion, so that the circular arc shape of the green body is substantially maintained.
The method of providing the cylindrical core at one-half of the loose height may be optimised by, for example, dividing the powder feed process into two equal parts by weight, placing the core into the powder after the first powder feed, and then placing the second powder. Alternatively, an auxiliary retainer plate may be used to place the core and retainer plate into the die cavity and then place all of the powder into the die cavity. And then, after the loose filling of the powder is finished, pulling the positioning plate out of the die cavity.
The flexible cylindrical core produced will play a role in reducing the incidence of cracks: because during the sintering, this core is inside the neodymium iron boron unburned bricks, goes into the stove along with the sintering unburned bricks together, and at the low temperature stage of vacuum intensification sintering (for example below 400 ℃), inside the heat can transmit the neodymium iron boron unburned bricks through this core, makes inside arc surface of neodymium iron boron unburned bricks also heat up simultaneously, has reduced the difference in temperature of inside arc surface and extrados, and then has reduced the shrinkage factor difference, is difficult to lead to the crackle to appear. Meanwhile, as the flexible cylindrical core is of a bonding mixed structure and has lower strength than a sintered green body, under the dual actions of heating the flexible cylindrical core and shrinking the green body wrapped outside the flexible cylindrical core, polyethylene glycol starts to decompose at high temperature, and is degassed and discharged along with organic matters such as lubricant in the green body, and meanwhile, the flexible cylindrical core starts to soften and shrink.
Because the neodymium iron boron sintering in the low-temperature stage is mainly liquid phase sintering, the porosity is very large, the shrinkage rate of the green body is relatively large, but the softening shrinkage process of the flexible cylindrical core is just coincident with the liquid phase sintering stage, the shrinkage of the inner ring can be fitted to a certain degree, heat can be continuously transferred, the inside and the outside of the green body are uniformly heated, and the proportion of the generation of sintering cracks is reduced.
When the temperature is increased continuously (for example, between 400 ℃ and 800 ℃), the polyethylene glycol of the flexible cylindrical core is decomposed gradually and completely, the volatilization is completed, the flexible cylindrical core loses the supporting function completely, and the flexible cylindrical core collapses into original powder. Most of the shrinkage process of the ring magnet is finished, and the liquid phase sintering of the second stage is carried out, so that the shrinkage rate is reduced, the density increasing rate is reduced, and the sintering crack is not generated.
The utility model discloses the forming device that the forming die of ring sintering neodymium iron boron magnetism body forms a complete set and uses, forming device's suppression equipment adopts present well-known hydraulic pressure type press, and the magnetic field power adopts direct current magnetic field, and 1.5~2.0 tesla are selected to the magnetic field size, and the mould material can select carbide for use, and suppression direction is selected from top to bottom and is suppressed, and magnetic field direction sets up to the horizontal direction.
For the convenience of explanation the utility model discloses in the beneficial effect in the aspect of the qualification rate of promotion sintered product, adopt behind the sintering ejection of compact the blank quantity of crackless ring and the quantitative ratio of the shaping unburned bricks of income stove to calculate the qualification rate.
For the convenience of explanation the utility model discloses in the beneficial effect of promotion material utilization rate aspect, the weight of the product after adopting the internal grinding machine to process calculates material utilization rate with the powder feeding weight ratio before the shaping.
Example 1:
a) preparing 20g of alumina powder and 40g of polyethylene glycol colloidal solution, uniformly mixing and stirring, carrying out isostatic pressing and pressure forming under 200Mpa in a cylindrical rubber mold, drying for 2 hours at 120 ℃, and preparing a flexible cylindrical core, wherein the diameter of the flexible cylindrical core is R1 and the length of the flexible cylindrical core is W1 and is 4 mm;
b) pouring 86g of powder into a forming die in a loose-packed state, wherein the loose-packed height L1=30mm of the poured powder;
c) embedding a flexible cylindrical core in the powder in a horizontal manner so that the height direction position thereof is at L1/2;
d) closing the pressure head, integrally forming the powder and the mold core under the condition that the magnetic field is 1.5 Tesla, and demolding to obtain a circular ring green body assembly;
e) after the ring green body assembly is packaged, the density is improved under the isostatic pressing of 200Mpa water;
f) sintering and densifying the green body assembly in a vacuum furnace at the sintering temperature of 1030 ℃ for 10 hours to obtain a circular ring sintered blank;
g) carrying out aging treatment on the ring sintering green body in an aging furnace to obtain a semi-finished product blank;
h) grinding the end face of the semi-finished blank on a plane grinding machine, wherein the grinding amount is 0.5mm;
i) the semi-finished blank with the end surface exposed with light is subjected to light exposure on the outer arc surface on an outer circle centerless grinder, and the grinding amount is 0.5mm;
j) the semi-finished blank with the outer arc surface exposed to light is subjected to light exposure on the inner arc surface on an inner circle grinding machine, and the grinding quantity is 0.5mm;
h) and slicing the semi-finished blank with the inner arc surface exposed to light in the axial direction on an inner circle slicing machine to obtain the circular machined product.
Example 2:
a) preparing 36g of alumina powder and 40g of polyethylene glycol colloidal solution, uniformly mixing and stirring, carrying out isostatic pressing and pressure forming under 200Mpa in a cylindrical rubber mold, drying for 2 hours at 120 ℃, and preparing a flexible cylindrical core, wherein the diameter of the flexible cylindrical core is R1 and the length of the flexible cylindrical core is W1 and is 5mm, and the length of the flexible cylindrical core is 50 mm;
b) pouring 86g of powder into a forming die in a loose-packed state, wherein the loose-packed height L1=31mm of the poured powder;
c) embedding a flexible cylindrical core in the powder in a horizontal manner so that the height direction position thereof is at L1/2;
d) closing the pressure head, integrally forming the powder and the mold core under the condition that the magnetic field is 1.5 Tesla, and demolding to obtain a circular ring green body assembly;
e) after the ring green body assembly is packaged, the density is improved under the isostatic pressing of 200Mpa water;
f) sintering and densifying the green body assembly in a vacuum furnace at the sintering temperature of 1030 ℃ for 10 hours to obtain a circular ring sintered blank;
g) carrying out aging treatment on the ring sintering green body in an aging furnace to obtain a semi-finished product blank;
h) grinding the end face of the semi-finished blank on a plane grinding machine, wherein the grinding amount is 0.5mm;
the subsequent machining process refers to example 1.
Comparative example 1:
a) preparing a stainless steel cylindrical core, wherein the diameter of the cylindrical core is R1 and is 5mm, and the length of the cylindrical core is W1 and is 50 mm;
b) pouring 86g of powder into a forming die in a loose-packed state, wherein the loose-packed height L1=30mm of the poured powder;
c) embedding a stainless steel cylindrical core into the powder in a horizontal manner so that the height direction thereof is at L1/2;
d) closing the pressing head, integrally molding the powder and the stainless steel core under the condition that the magnetic field is 1.5 Tesla, and demolding to obtain a circular ring green body assembly;
e) after the ring green body assembly is packaged, the density is improved under the isostatic pressing of 200Mpa water, and then the stainless steel core is taken out;
f) sintering and densifying the green body in a vacuum furnace at the sintering temperature of 1030 ℃ for 10 hours to obtain a circular ring sintered blank;
the subsequent machining process was the same as in example 1.
In the process of continuously producing a plurality of circular ring sintering blanks, the inner wall of the circular ring green blank is easy to fall off in the process of taking out the stainless steel core in the step e, and the phenomenon of meat deficiency in most of the circular ring sintering blanks after sintering is caused.
Comparative example 2:
a) preparing 45g of alumina powder and 60g of polyethylene glycol colloidal solution, uniformly mixing and stirring, carrying out isostatic pressing and pressure forming under 200Mpa in a cylindrical rubber mold, drying for 2h at 120 ℃, and preparing a flexible cylindrical core, wherein the diameter of the flexible cylindrical core is R1 of 6mm, the length of W1 of 50mm, and the diameter of the flexible cylindrical core in the comparative example is larger than that of the flexible cylindrical core adopted in the application;
b) pouring 86g of powder into a forming die in a loose-packed state, wherein the loose-packed height L1=35mm of the poured powder;
c) embedding a flexible cylindrical core in the powder in a horizontal manner so that the height direction position thereof is at L1/2;
d) closing the pressure head, integrally forming the powder and the mold core under the condition that the magnetic field is 1.5 Tesla, and demolding to obtain a circular ring green body assembly;
e) after the ring green body assembly is packaged, the density is improved under the isostatic pressing of 200Mpa water;
f) sintering and densifying the green body assembly in a vacuum furnace at the sintering temperature of 1030 ℃ for 10 hours to obtain a circular ring sintered blank;
the subsequent machining process was the same as in example 1.
Comparative example 3:
a) in a loose state, 118g of the powder was poured into a forming mold;
d) closing a pressure head, forming the powder under the condition that the magnetic field is 1.5 Tesla, and obtaining a cylindrical green body after demolding, wherein in the comparative example 3, no core is adopted in the mold during forming;
c) after the cylindrical green body is packaged, the density is improved under the isostatic pressure of 200Mpa water;
f) sintering and densifying the green body in a vacuum furnace at the sintering temperature of 1030 ℃ for 10 hours to obtain a cylindrical sintered blank;
h) grinding the end face of the sintered blank on a plane grinding machine, wherein the grinding amount is 0.5mm;
i) the blank with the end surface exposed with light is subjected to light exposure on the outer arc surface on an outer circle centerless grinding machine, and the grinding amount is 0.5mm;
j) processing the blank with the outer arc surface exposed to light into an inner circular hole by using a drilling cutter;
the subsequent machining process was the same as in example 1. With the production process of comparative example 3, it takes a long time to drill holes due to the presence of step j, and at the same time, there is a great waste of material.
Comparative example 4:
a) pouring 86g of powder into a forming mould in a loose-packed state, the loose-packed height L1=35 mm;
b) horizontally putting an aluminum cylindrical core with the diameter of 5mm into the loose powder, and enabling the aluminum core to be positioned at the position L1/2;
c) closing a pressure head, forming the powder under the condition that the magnetic field is 1.5 Tesla, and demolding to obtain a cylindrical green body, wherein the green body contains an aluminum core;
d) after the cylindrical green body is packaged, the density is improved under the isostatic pressure of 200Mpa water;
e) sintering the cylindrical green body with the aluminum core inside at the sintering temperature of 1030 ℃ for 10 hours to obtain a sintered blank;
after the step e), observing that the inside of the sintering blank at the moment is fused with the inner arc surface of the sintering blank due to the existence of aluminum, the appearance and the structure of the magnet are seriously damaged, and the magnet cannot be put into subsequent production, so that the utilization rate of the material cannot be counted.
Comparative example 5:
a) pouring 86g of powder into a forming mould in a loose-packed state, the loose-packed height L1=35 mm;
b) horizontally putting a ceramic cylindrical core with the diameter of 5mm into the loose powder, and enabling the aluminum core to be positioned at the position L1/2;
c) closing a pressure head, forming the powder under the condition that the magnetic field is 1.5 Tesla, and obtaining a cylindrical green body after demolding, wherein the green body contains a ceramic core;
d) after the cylindrical green body is packaged, the density is improved under the isostatic pressure of 200Mpa water;
e) sintering the cylindrical green body with the ceramic core inside at 1030 ℃ for 10 hours to obtain a sintered blank;
and e) observing the appearance condition of the blank after the step e), and finding that the blank is totally cracked after being sintered due to the fact that the ceramic core which has high hardness and cannot shrink along with the blank is arranged inside the blank, and cannot be put into subsequent production, and the utilization rate of materials cannot be counted.
In the form of table 1, the blank yield and the material utilization rate of each example and comparative example were counted.
| Categories | Mold core | Weight of feed powder (g) | Weight (g) after internal grinding | Material utilization rate | Sintering percent of pass of blank |
| Example 1 | Flexibility of 4mm | 86 | 73 | 85% | 98% |
| Example 2 | Flexibility 5mm | 86 | 70 | 81% | 96% |
| Comparative example 1 | Stainless steel extraction | 86 | 66 | 77% | 50% |
| Comparative example 2 | Flexibility of 6mm | 86 | 71 | 83% | 70% |
| Comparative example 3 | Core-free | 118 | 71 | 60% | 99% |
| Comparative example 4 | Aluminum core-not-removed | 86 | Raw material processing | Not counting | 0% |
| Comparative example 5 | Ceramic without taking out | 86 | Raw material processing | Not counting | 0% |
Table 1 statistics table for the percent of pass and material utilization of blanks
As can be seen from comparison of the effects of the examples and comparative examples, except for comparative example 3 in which the weight of the powder to be fed was the same, the method and mold of the present application were used in examples 1-2, and stainless steel cylindrical cores were used in comparative example 1, flexible cylindrical cores were used in comparative example 2, aluminum cylindrical cores were used in comparative example 4, and ceramic cylindrical cores were used in comparative example 5.
Through processing back test and judgement, can find that the product material utilization who adopts the utility model discloses the mould of method obtains is high and the qualification rate is high, and the comparative example is though material utilization is high, because the flexible cylinder core that this comparative example adopted, and the size of flexible cylinder core is not in the scope that this application scheme required, therefore the qualification rate is low.
Comparative example 3 is not formed with any core, and is significantly heavy in powder feeding, but is not high in material utilization rate, and is high in yield because magnetic powder is used in its entirety.
Therefore, use the utility model discloses a ring form neodymium iron boron magnetism body of process method and device preparation can show improvement material utilization and blank sintering qualification rate.
The above examples are only preferred embodiments of the present invention, and should not be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, many alternatives and modifications can be made without departing from the spirit of the invention, and these alternatives and modifications are all within the scope of the invention.
Claims (5)
1. The utility model provides a forming die of ring form sintered neodymium iron boron magnet which characterized in that:
including the major part, go up the pressure head, the pressure head down, the die cavity, wherein the major part includes two relative non-magnetic conduction curb plates, two relative magnetic conduction curb plates, in the space that forms between two non-magnetic conduction curb plates and two magnetic conduction curb plates, the pressure head is located the bottom in space down, it is located the top in space to go up the pressure head, the die cavity is located between pressure head and the pressure head down, place flexible cylinder core in the die cavity, after the neodymium iron boron magnetic powder of putting loose dress state is put into to the die cavity, flexible cylinder core is placed in the die cavity, the axial direction of flexible cylinder core is the horizontal direction, and parallel with the magnetic field direction between two magnetic conduction curb plates.
2. The forming die of the annular sintered neodymium-iron-boron magnet as claimed in claim 1, wherein: the length W of the flexible cylindrical core is consistent with the distance between the inner walls of the two non-magnetic-conductive side plates, and the radius R of the flexible cylindrical core is smaller than the distance of one half between the two non-magnetic-conductive side plates.
3. The forming die of the annular sintered neodymium-iron-boron magnet as claimed in claim 1, wherein: the radius R of the flexible cylindrical core is more than 2mm and less than 5 mm.
4. The forming die of the annular sintered neodymium-iron-boron magnet as claimed in claim 1, wherein: the lower pressure head is fixedly or movably connected to the bottom of a space formed between the two non-magnetic-conductive side plates and the two magnetic-conductive side plates, when the lower pressure head is movably connected, the lower pressure head moves back and forth in the space, the upper pressure head is movably connected to the top of the space between the two non-magnetic-conductive side plates and the two magnetic-conductive side plates, and the upper pressure head moves back and forth in the space.
5. The forming die of the annular sintered neodymium-iron-boron magnet as claimed in claim 1, wherein: and one sides of the upper pressure head and the lower pressure head facing the flexible cylindrical core are both concave arc surfaces.
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| CN202021491072.8U CN212230241U (en) | 2020-07-26 | 2020-07-26 | Forming die of annular sintered neodymium iron boron magnet |
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| CN202021491072.8U CN212230241U (en) | 2020-07-26 | 2020-07-26 | Forming die of annular sintered neodymium iron boron magnet |
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| CN202021491072.8U Active CN212230241U (en) | 2020-07-26 | 2020-07-26 | Forming die of annular sintered neodymium iron boron magnet |
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Address after: Fushan District, Shandong city of Yantai province Yongda Street 265500 No. 888 Patentee after: Yantai Dongxing magnetic material Co.,Ltd. Address before: Fushan District, Shandong city of Yantai province Yongda Street 265500 No. 888 Patentee before: YANTAI SHOUGANG MAGNETIC MATERIALS Inc. |
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