CN111968814A - Powder distribution device and powder distribution method thereof, and manufacturing method of NdFeB series sheet magnet - Google Patents
Powder distribution device and powder distribution method thereof, and manufacturing method of NdFeB series sheet magnet Download PDFInfo
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- CN111968814A CN111968814A CN202010664221.4A CN202010664221A CN111968814A CN 111968814 A CN111968814 A CN 111968814A CN 202010664221 A CN202010664221 A CN 202010664221A CN 111968814 A CN111968814 A CN 111968814A
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- 239000000843 powder Substances 0.000 title claims abstract description 262
- 238000000034 method Methods 0.000 title claims abstract description 63
- 238000009826 distribution Methods 0.000 title claims abstract description 58
- 229910001172 neodymium magnet Inorganic materials 0.000 title claims description 17
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 238000005303 weighing Methods 0.000 claims abstract description 66
- 238000010408 sweeping Methods 0.000 claims abstract description 30
- 238000005192 partition Methods 0.000 claims abstract description 13
- 239000001257 hydrogen Substances 0.000 claims description 13
- 229910052739 hydrogen Inorganic materials 0.000 claims description 13
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 10
- 210000001503 joint Anatomy 0.000 claims description 9
- 238000005245 sintering Methods 0.000 claims description 9
- 239000011362 coarse particle Substances 0.000 claims description 6
- 230000006835 compression Effects 0.000 claims description 6
- 238000007906 compression Methods 0.000 claims description 6
- 238000004880 explosion Methods 0.000 claims description 6
- 239000000155 melt Substances 0.000 claims description 5
- 238000000465 moulding Methods 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 4
- 229910045601 alloy Inorganic materials 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims description 3
- 238000004512 die casting Methods 0.000 claims description 3
- 150000002431 hydrogen Chemical class 0.000 claims description 3
- 238000010902 jet-milling Methods 0.000 claims description 3
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 3
- 150000002910 rare earth metals Chemical class 0.000 claims description 3
- 239000004744 fabric Substances 0.000 claims description 2
- 238000010410 dusting Methods 0.000 claims 3
- 238000011049 filling Methods 0.000 abstract description 8
- 238000005054 agglomeration Methods 0.000 abstract description 7
- 230000002776 aggregation Effects 0.000 abstract description 7
- 239000011261 inert gas Substances 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 238000009825 accumulation Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 238000009694 cold isostatic pressing Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 239000006247 magnetic powder Substances 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009740 moulding (composite fabrication) Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
- H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
- H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
- H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
- H01F41/0266—Moulding; Pressing
Abstract
The invention provides a powder distributing device, which comprises a powder distributor and a die matched with the powder distributor for use; the powder distributor comprises a bottom plate, a side wall, a powder sweeping plate, at least two funnels and powder distributing valves, wherein the side wall is connected with the bottom plate and forms an accommodating cavity with the bottom plate; the bottom plate is provided with through holes which are uniformly distributed and penetrate through the bottom plate, and the powder distributor also comprises weighing devices which correspond to the funnels one by one; the mold comprises a mold body with an accommodating space and a partition plate for dividing the accommodating space into at least two mold cavities; the powder distributing method comprises the working procedures of weighing powder, pouring powder, distributing powder and closing the die. The powder distributing device can reduce powder agglomeration; the weight value of the powder filled in each die cavity can be accurately controlled by the arrangement of the weighing device, and the filling quantity of the powder in each die cavity is ensured to be consistent, so that the batch uniform filling and powder distribution of the magnets are realized.
Description
[ technical field ] A method for producing a semiconductor device
The invention relates to the technical field of near-net-shape processing of magnets, in particular to a powder distribution device and a powder distribution method thereof, and a manufacturing method of an NdFeB system sheet magnet.
[ background of the invention ]
With the improvement of performance and experience requirements of people, acoustic components are developing towards structures with small volume, high energy density and more complexity. Near net shape forming becomes an important direction for preparing high-performance sintered neodymium iron boron (NdFeB) magnets, and the method for preparing the magnets at the present stage obtains magnetic steel sheets with the thickness of about 1mm through oriented forming, cold isostatic pressing, sintering and mechanical cutting.
In the prior art, although cold isostatic pressing is cancelled, a method for preparing magnetic steel with the thickness of 6mm by filling powder into a die for molding is adopted, and the magnetic steel is prepared under the condition of strictly controlling oxygen, so that the performance is ensured, the cutting loss is reduced for subsequent processing of the magnet, and the preparation cost of the magnet is reduced. However, for near-net shape forming of a thin magnet with a smaller size, since the width of the cavity is small and the relative contact friction area between the powder and the cavity is large, the powder is difficult to be uniformly distributed in each cavity of the mold due to the friction force between the powder and the cavity and the agglomeration of the powder. Gaps caused by the agglomeration of powder in the die cavity lead to inconsistent powder distribution at each position in the die cavity, uneven sizes of blanks and green bodies caused by different internal stresses at different positions of the pressed magnet, unstable performance and difficulty in realizing batch production. Furthermore, for thinner and smaller magnets with a total powder distribution of only a few grams, it is desirable to achieve a mass error of as low as 1% between the cavities of the same mold, which still presents a significant challenge.
Therefore, it is necessary to provide a powder distributing device and a powder distributing method to solve the above problems.
[ summary of the invention ]
The invention aims to provide a powder distribution device which can reduce powder agglomeration and distribute powder uniformly.
In a first aspect, the invention provides a powder distribution device for accurately filling powder into multiple thin die cavities simultaneously, which comprises a powder distributor and a die matched with the powder distributor; the powder distributor comprises a bottom plate, a side wall which is connected with the bottom plate and forms an accommodating cavity with the bottom plate, a powder sweeping plate for sweeping powder in the accommodating cavity, and at least two funnels which are in butt joint with one side of the bottom plate, which is far away from the accommodating cavity, wherein each funnel comprises a funnel inlet which is in butt joint with one side of the bottom plate and is communicated with the accommodating cavity, a powder distributing valve which is arranged at the funnel inlet and can be opened and closed, and a funnel outlet which is correspondingly communicated with the funnel inlet; the powder distributor also comprises weighing devices which are arranged opposite to the hopper outlets one by one, and each weighing device is abutted against the hopper outlet and can move freely; the mould is arranged on one side of the weighing device, which is far away from the powder distributor; the die comprises a die body with an accommodating space and a partition board accommodated in the accommodating space, the accommodating space is divided into at least two die cavities by the partition board, and die cavity openings corresponding to the weighing devices are formed in one sides of the die cavities corresponding to the powder distributor.
Preferably, each funnel inlet corresponds to the same number of through holes on the bottom plate, and the aperture of each through hole is the same.
More preferably, the ratio of the funnel volume to the mold cavity volume is 3: 2.
More preferably, the outlet of the funnel is provided with a mesh screen.
Preferably, the powder distribution device further comprises a vibration device for driving the funnel to vibrate at high frequency.
More preferably, the thickness of the mould cavity in a direction perpendicular to the base plate is 0.1mm to 100 mm.
More preferably, the thickness of the partition plate in a direction parallel to the bottom plate is 0.1mm to 20 mm.
Preferably, the powder distribution device further comprises a controller, a weighing sensor electrically connected with the controller is arranged on the weighing device, the powder distribution valve is an electric control valve electrically connected with the controller, and the weighing device is an electric control balance supporting plate electrically connected with the controller; and when the controller learns that the weight value obtained by the weighing device reaches a preset value through the weighing sensor, the controller controls the powder distributing valve to be automatically closed and controls the weighing device to be automatically moved away and not to close the outlet of the funnel.
Preferably, the powder distribution device further comprises an air hammer device which is connected with the funnel, knocks the funnel and blows air from the inlet of the funnel.
More preferably, the weighing apparatus has an accuracy of not less than 0.01 g.
In a second aspect, the invention provides a powder distribution method based on the device, which comprises the following steps:
(1) and (3) powder pouring: keeping a powder distributing valve closed, and pouring powder into the accommodating cavity of the powder distributor;
(2) a powder sweeping process: keeping the weighing devices to abut against the outlet of the funnel, opening the powder distribution valve, using a powder sweeping plate to sweep the powder in the accommodating cavity into the funnel, weighing and feeding back a weight value by the weighing devices, and closing the corresponding powder distribution valve when the weight value of a certain weighing device reaches a preset value;
(3) powder distribution procedure: removing a weighing device allows the powder in the hopper corresponding to the weighing device to slide into the corresponding die cavity.
Preferably, the method further comprises the step of setting a preset weight value for the weighing device.
Preferably, in the powder distribution process, the hopper is vibrated so that the powder in the hopper smoothly slides into the corresponding die cavity.
Preferably, in the powder distributing process, an air hammer device is used for knocking a powder distributing funnel or blowing air from the funnel inlet to the funnel outlet so that the powder in the funnel smoothly slides into the die cavity corresponding to the funnel.
More preferably, the median diameter of the powder in the powder pouring process is 1-8 μm, and the loose packing density of the powder is 0.5g/cm3-3.5g/cm3。
More preferably, the powder distribution method further comprises the following steps:
and a die assembly step, after the powder distribution step, utilizing a stamping head and a die cavity of the die filled with the powder to carry out die assembly and butt joint so as to prepare an orientation compression type.
In a third aspect, the present invention provides a method for producing an NdFeB-based thin sheet magnet, the method comprising:
a rapid hardening process, namely putting NdFeB alloy with certain mass into a vacuum rapid hardening furnace to prepare a melt spun strip with certain thickness;
a hydrogen explosion procedure, namely putting the slinger into a hydrogen explosion furnace, introducing hydrogen, and utilizing the reaction of rare earth and the hydrogen to break the slinger into coarse particles of 300-;
a jet milling process, wherein the coarse particles are crushed into fine powder by a jet crushing device, and the median particle size of the fine powder is 1-8 μm;
a powder distributing and film combining process, namely distributing powder to the powder by the powder distributing method to enable the powder to be filled into the die cavity for orientation compression;
an orientation molding step of applying magnetic field orientation to the powder filled in the cavity and die-casting the powder into a molded body;
and a sintering step of sintering the molded body to obtain the NdFeB thin sheet magnet.
The invention has the beneficial effects that: the bottom plate of the powder distributor is provided with the hole and the powder sweeping plate, so that powder agglomeration can be reduced; the weight value of the powder filled in each die cavity can be accurately controlled by the arrangement of the weighing device, so that the consistency of the filling amount of the powder in each die cavity is ensured, and the weight of the powder in each die cavity is accurately controlled.
[ description of the drawings ]
FIG. 1 is a schematic structural view of a powder distribution device according to the present invention;
FIG. 2 is a schematic top view of a bottom plate of the powder distribution device of the present invention;
FIG. 3A is a schematic view of a powder pouring process of the powder distributing device of the present invention;
FIG. 3B is a schematic view of a powder sweeping process of the powder distributing device according to the present invention;
FIG. 3C is a schematic diagram of a powder distributing process of the powder distributing device according to the present invention;
FIG. 4 is a schematic view showing the orientation direction of a magnet in the preparation of a magnet according to an embodiment of the present invention;
FIG. 5 is a schematic illustration of a magnet performance verification location made in accordance with an embodiment of the present invention;
fig. 6 is a schematic diagram of electrical connections of a controller according to an embodiment of the present invention.
[ detailed description ] embodiments
The invention is further described with reference to the following figures and embodiments.
Example 1
The invention provides a powder distributing device, which comprises a powder distributor 1 and a mould 2, wherein the mould 2 is matched with the powder distributor 1 for use, as shown in figures 1-3.
The powder distributor comprises a bottom plate 11, a side wall 12, a powder sweeping plate 15, at least two funnels 13 and a weighing device 14, wherein the funnels 13 are in butt joint with one side of the bottom plate 11, which is far away from the containing cavity 16. The side wall 12 is connected with the bottom plate 11 to form a containing cavity 16, the powder sweeping plate 15 is used for sweeping powder in the containing cavity 16, the bottom plate 11 is provided with through holes 111 (shown in fig. 3) which are uniformly distributed and penetrate through the bottom plate, and the weighing devices 14 are arranged at the outlet 132 of the funnel and correspond to the funnels 13 one by one. Specifically, each of the weighing devices 14 is disposed at the funnel outlet 132 and is disposed opposite to the funnel outlet, each of the weighing devices 14 abuts against the funnel outlet 132 and can move freely, the abutting of the weighing devices 14 against the funnel outlet 132 can be used for sealing the powder flowing from the receiving cavity 16 into the funnel 13 through the through hole 111, and the removal of the weighing devices 14 can pour the weighed powder in the funnel 13 into the mold cavity 23.
Preferably, the powder distributor further comprises a powder pouring shovel 17, and the powder pouring shovel 17 is used for pouring powder to be distributed into the containing cavity 16.
Specifically, the funnel 13 includes a funnel inlet 131, a funnel outlet 132, and a powder dispensing valve 133. The funnel inlet 131 is in butt joint with one side of the bottom plate 11 and is communicated with the containing cavity 16 through a through hole 111, the funnel outlet 132 is correspondingly communicated with the funnel inlet 131, the powder distributing valve 133 is arranged between each funnel inlet 131 and the through hole 111 corresponding to the funnel 13, and the powder distributing valve 133 can be opened and closed; when each powder distributing valve 133 is closed, the powder distributing valve can completely cover the through hole 111 corresponding to each powder distributing funnel inlet 131, and can prevent the through hole 111 and the funnel inlet 131 corresponding to the through hole 111 from being communicated, so that the powder in the accommodating cavity 16 is prevented from flowing into the funnel 13 through the through hole 111. When the powder distributing valve 133 is opened, the powder in the receiving cavity 16 can flow into the funnel 13 through the through hole 111.
Preferably, each of the funnel inlets 131 corresponds to the same number of through holes 111 on the bottom plate 11, and the aperture of each through hole 111 is the same.
Preferably, a mesh screen (not shown) is provided at the funnel outlet 132.
Preferably, the weighing device 14 has an accuracy of not less than 0.01 g.
Preferably, the ratio of the volume of the funnel 13 to the volume of the mold cavity 23 is greater than 1: 1. Accumulation of powder weighing errors caused by filling the die cavity 23 with powder in the hopper 13 for a plurality of times can be avoided.
In this embodiment, the aperture of the through hole 111 is 40 μm, the volume ratio of the funnel 13 to the cavity 23 is 3:2, the mesh screen aperture is 40 meshes, the weighing device 14 is specifically an openable balance support plate which is disposed at the funnel outlet 132 and corresponds to the funnel 13 one by one, and the precision of the balance support plate is 0.01 g.
The mould 2 is arranged on one side of the weighing device 14, which is far away from the powder distributor; the mold 2 includes a mold body 21, a partition plate 22, a cavity 23, and a cavity opening 231. The die body 21 is provided with an accommodating space 212, the partition plate 22 is accommodated in the accommodating space 212, the partition plate 22 divides the accommodating space 212 into at least two die cavities 23, and a die cavity opening 231 corresponding to the weighing device 14 is formed in one side of the die cavity 23 corresponding to the powder distributor. In this embodiment, the weighing device 14 is used to weigh the powder in the hopper 13 during the powder distribution process by abutting the balance blade against the hopper outlet 132. As shown in fig. 3B, when the weight value of a certain weighing device 14 reaches a preset value, the corresponding powder distributing valve 133 is closed. As shown in fig. 3C, the mold 2 can be used for the mold closing process after the powder distributor is removed after the powder distribution.
Preferably, the number of cavities 23 is 2-200.
Preferably, the thickness of the mold cavity 23 in a direction perpendicular to the bottom plate 11 is 0.1mm to 100 mm. The thickness of the formed magnet is effectively controlled.
Preferably, the partition 22 has a thickness of 0.1mm to 20mm in a direction parallel to the bottom plate 11. Prevent excessive accumulation of magnetic powder on the cross section of the partition plate.
In this embodiment, the mold 2 comprises eight mold cavities 23 of equal size; the thickness of the die cavity 23 in the direction perpendicular to the bottom plate 11 is 4mm, and the die cavity 23 is used for preparing a thin magnet with the thickness less than 3mm, and the length and the width of the die cavity 23 are respectively 30mm and 25 mm; the thickness of the partition 22 in a direction parallel to the bottom plate 11 is 5 mm.
In particular, the powder distribution device also comprises a vibration device (not shown in the figures) for driving the hopper 13 to vibrate at high frequency.
Specifically, as shown in fig. 6, the powder distribution device further includes a controller, a weighing sensor electrically connected to the controller is disposed on the weighing device 14, the powder distribution valve 133 is an electrically controlled valve electrically connected to the controller, and the weighing device 14 is a balance support plate electrically connected to the controller; when the controller knows that the weight value obtained by the weighing device 14 reaches a preset value through the weighing sensor, the controller controls the powder distributing valve 133 to be automatically closed, and controls the balance support plate to be automatically moved away and not to close the hopper outlet 132, so that the powder weighed to the preset weight value in the hopper 13 flows into the die cavity.
Preferably, the powder distribution device further comprises an air hammer device which is connected with the funnel 13 and is used for knocking the funnel 13 and blowing air from the funnel inlet 131.
The invention provides a powder distributing method based on the powder distributing device, which comprises the following steps:
(1) and (3) powder pouring: keeping the powder dispensing valve 133 closed, pouring the powder into the accommodating cavity 16 of the powder dispenser, as shown in fig. 3A;
(2) a powder sweeping process: keeping the weighing devices 14 abutting against the hopper outlet 132, opening the powder distributing valves 133, sweeping the powder in the accommodating cavities 16 into the hopper 13 by using the powder sweeping plate 15, weighing and feeding back the weight value by the weighing devices 14, and closing the corresponding powder distributing valves 133 when the weight value of a certain weighing device 14 reaches a preset value, as shown in fig. 3B;
(3) powder distribution procedure: removing a weighing device 14 allows the powder in the hopper 13 corresponding to the weighing device 14 to slide into the corresponding die cavity 23, as shown in fig. 3C.
Powder agglomeration is a key factor for preventing uniform molding of a magnet, the powder sweeping plate 15 is arranged in the magnet powder stirring device, powder balls of powder can be rapidly stirred to uniformly sweep powder, meanwhile, the powder sweeping plate 15 stirs the powder balls to enable the powder balls to rub with the bottom plate 11 and the through holes 111, and the agglomerated powder balls can be scattered, the distance between the powder sweeping plate 15 and the bottom plate 11 is smaller than or equal to 5mm in the magnet powder stirring device, and more preferably, the distance between the powder sweeping plate 15 and the bottom plate 11 is smaller than or equal to 2 mm. Specifically, the powder sweeping plate 15 is used for sweeping powder in the containing cavity 16 along the direction indicated by the arrow in fig. 3B, and can reciprocate along the containing cavity 16 of the powder distributor, and the powder sweeping height and the powder sweeping frequency of the powder sweeping plate 15 can be set according to a specific process. Preferably, the frequency of the reciprocating motion of the powder sweeping plate 15 in the containing cavity 16 is 10 Hz-200 Hz.
In this embodiment, the height of the powder sweeping plate 15 is 2mm, and the powder sweeping frequency is 100 Hz.
Preferably, the powder distribution method further includes a step of setting a preset weight value for the weighing device 14. In this example, the predetermined weight value was 9.44 g.
Preferably, in the powder distribution process, the hopper 13 is vibrated so that the powder in the hopper 13 smoothly slides into the corresponding cavity 23.
Preferably, in the powder distributing step, the powder distributing hopper 13 is hit by an air hammer device or air is blown from the hopper inlet 131 to the hopper outlet 132, so that the powder in the hopper 13 smoothly slides into the mold cavity 23 corresponding to the hopper 13.
Preferably, the median diameter of the powder in the powder pouring process is 1-8 μm, and the loose packing density of the powder is 0.5g/cm3～3.5g/cm3。
In this example, the median diameter of the powder in the powder pouring step was 5 μm, and the bulk density of the powder was 3.11g/cm3。
Preferably, the powder distributing method further comprises a mold clamping step, after the powder distributing step, the mold clamping step is carried out, and after the powder distributing step, the mold clamping step and the mold cavity 23 of the mold 2 containing the powder are utilized to carry out mold clamping butt joint so as to prepare the orientation compression mold.
The present invention also provides a method for producing an NdFeB-based thin sheet magnet, the method comprising the steps of:
a rapid hardening process, namely putting NdFeB alloy with certain mass into a vacuum rapid hardening furnace to prepare a melt spun strip with certain thickness;
a hydrogen explosion procedure, namely putting the slinger into a hydrogen explosion furnace, introducing hydrogen, and utilizing the reaction of rare earth and the hydrogen to break the slinger into coarse particles of 300-;
jet milling process, under the protection of inert gas, specifically selecting N2Ar and the like, and crushing the coarse particles into fine powder by using airflow crushing equipment, wherein the median particle size of the fine powder is 1-8 mu m;
cloth powder and film combination process, under the protection of inert gas, N is specifically selected2Ar, etc., the powder is subjected to powder distribution by the above-mentioned powder distribution method, and the powder is filled into the cavity 23 to prepare an orientation compact;
orientation profiling process, under the protection of inert gas, specifically selecting N2Ar, etc., applying magnetic field orientation to the powder filled in the cavity 23, and die-casting into a molded body;
sintering process, under the protection of inert gas, specifically selecting N2Ar or the like, and sintering the molded body to obtain the NdFeB-based thin sheet magnet. Specifically, at the temperature rise speed of 5-10 ℃/min, firstly raising the temperature to 300 ℃, preserving the temperature for 2h, and discharging adsorbed gas; then heating to 550 ℃, preserving the heat for 2 hours, and discharging hydrogen; and then the temperature is increased to 1020 ℃ and 1100 ℃, and the temperature is kept for 2h to ensure that the NdFeB system sheet magnet is obtained after the sintering shrinkage of the molded body.
Preferably, in the rapid hardening process, the thickness of the melt spun band is 0.15mm to 0.45 mm.
Preferably, in the orientation profiling step, the intensity of the magnetic field of the orientation profiling is 1.2T-9T.
Preferably, the sintering process further comprises the following steps: removing the magnetic field applied on the formed body, and applying a magnetic field with the strength of 0.05T-0.2T opposite to the direction of the magnetic field on the formed body.
Preferably, the punch clamped with the die 2 can be pressed up and down in a floating manner, and is clamped with the die cavity 23 at a molding pressure of 2 t-80 t.
In this embodiment, N is specifically selected as the inert gas2The thickness of the melt spun in the rapid hardening process is 0.3mm, the forming pressure of a stamping head is 40T, the intensity of a magnetic field of the orientation profiling is 4T, and the orientation direction is shown as an arrow direction in fig. 4; the strength of the molded body opposite to the orientation compression magnetic field is 0.1T, so that the surface of the molded magnet is free from magnetic powder burrs.
Eight NdFeB-based flake magnets, numbered a to h, the thickness, weight and magnet density (g/cm) of the eight magnets, were obtained according to the eight cavities of example 13) The performance parameters of (A) are shown in the following table.
The mass and density of the magnet obtained after powder distribution in the eight die cavities are close, the mass of the magnet is close, and the error of the density of the magnet is 0.1g/cm3The resulting magnet in each mold cavity is approximated by the six-position thickness values shown in fig. 5. In summary, the powder distribution device and the powder distribution method thereof provided by the invention can efficiently and accurately and uniformly fill powder into multiple cavities at the same time, and further can obtain a magnet with uniform weight, magnet density and magnet thickness.
The invention has the beneficial effects that: the bottom plate of the powder distributor is provided with the hole and the powder sweeping plate, so that powder agglomeration can be reduced; the weight value of the powder filled in each die cavity can be accurately controlled by the arrangement of the weighing device, the filling quantity of the powder in each die cavity is ensured to be consistent, and the weight of the powder in each die cavity is accurately controlled, so that the batch uniform filling of the powder of the magnets is realized, and the near-net forming of the magnet preparation below 3mm is realized.
While the foregoing is directed to embodiments of the present invention, it will be understood by those skilled in the art that various changes may be made without departing from the spirit and scope of the invention.
Claims (17)
1. A powder distribution device for preparing NdFeB series slice magnet is characterized by comprising a powder distributor and a die matched with the powder distributor;
the powder distributor comprises a bottom plate, a side wall which is connected with the bottom plate and forms an accommodating cavity with the bottom plate, a powder sweeping plate for sweeping powder in the accommodating cavity, and at least two funnels which are in butt joint with one side of the bottom plate, which is far away from the accommodating cavity, wherein each funnel comprises a funnel inlet which is in butt joint with one side of the bottom plate and is communicated with the accommodating cavity, a powder distributing valve which is arranged at the funnel inlet and can be opened and closed, and a funnel outlet which is correspondingly communicated with the funnel inlet; the bottom plate is provided with through holes which are uniformly distributed and penetrate through the bottom plate, the through holes are arranged corresponding to the hopper inlets, each powder distributing valve completely covers the through hole corresponding to each powder distributing hopper inlet when being closed,
the powder distributor also comprises weighing devices which are arranged opposite to the hopper outlets one by one, and each weighing device is abutted against the hopper outlet and can move freely;
the mould is arranged on one side of the weighing device, which is far away from the powder distributor; the die comprises a die body with an accommodating space and a partition board accommodated in the accommodating space, the accommodating space is divided into at least two die cavities by the partition board, and die cavity openings corresponding to the weighing devices are formed in one sides of the die cavities corresponding to the powder distributor.
2. The powder distribution device according to claim 1, wherein each funnel inlet corresponds to the same number of through holes on the bottom plate, and the diameter of each through hole is the same.
3. The powder distribution device of claim 1, wherein the ratio of the funnel volume to the mold cavity volume is 3: 2.
4. Powder distribution device according to claim 1, characterized in that a mesh screen is provided at the funnel outlet.
5. The powder distribution device according to claim 1, further comprising a vibration device for driving the hopper to vibrate at high frequency.
6. Cloth powder device according to claim 1, characterised in that the mould cavity has a thickness in the direction perpendicular to the base plate of 0.1-100 mm.
7. Powder distribution device according to claim 1, characterised in that the partition has a thickness in the direction parallel to the base plate of 0.1-20 mm.
8. The powder distributing device according to claim 1, further comprising a controller, wherein a weighing sensor electrically connected with the controller is arranged on the weighing device, the powder distributing valve is an electrically controlled valve electrically connected with the controller, and the weighing device is an electrically controlled balance supporting plate electrically connected with the controller; and when the controller learns that the weight value obtained by the weighing device reaches a preset value through the weighing sensor, the controller controls the powder distributing valve to be automatically closed and controls the weighing device to be automatically moved away and not to close the outlet of the funnel.
9. The powder distribution device according to claim 1, further comprising an air hammer device connected to the hopper and adapted to knock the hopper and blow air from the inlet of the hopper.
10. A dusting device according to claim 1, characterized in that the weighing device has an accuracy of not less than 0.01 g.
11. A powder distributing method based on the powder distributing device of any one of claims 1 to 10, characterized in that the powder distributing method comprises the following steps:
(1) and (3) powder pouring: keeping a powder distributing valve closed, and pouring powder into the accommodating cavity of the powder distributor;
(2) a powder sweeping process: keeping the weighing devices to abut against the outlet of the funnel, opening the powder distribution valve, using a powder sweeping plate to sweep the powder in the accommodating cavity into the funnel, weighing and feeding back a weight value by the weighing devices, and closing the corresponding powder distribution valve when the weight value of a certain weighing device reaches a preset value;
(3) powder distribution procedure: removing a weighing device allows the powder in the hopper corresponding to the weighing device to slide into the corresponding die cavity.
12. The powder distribution method according to claim 11, further comprising a step of setting a preset weight value for the weighing device.
13. Powder distribution method according to claim 11, characterized in that in the powder distribution process, the hopper is vibrated so that the powder in the hopper slides smoothly into the corresponding die cavity.
14. The powder distribution method according to claim 11, wherein in the powder distribution process, a powder distribution funnel is knocked by an air hammer device or air is blown from the funnel inlet to the funnel outlet, so that the powder in the funnel can smoothly slide into the mold cavity corresponding to the funnel.
15. The dusting method of claim 11, wherein the median particle size of the powder in the powder pouring step is 1 μm to 8 μm, and the bulk density of the powder is 0.5g/cm3-3.5g/cm3。
16. The dusting method of claim 11, further comprising:
and a die assembly step, after the powder distribution step, utilizing a stamping head and a die cavity of the die filled with the powder to carry out die assembly and butt joint so as to prepare an orientation compression type.
17. A method for producing an NdFeB-based thin sheet magnet, comprising:
a rapid hardening process, namely putting NdFeB alloy with certain mass into a vacuum rapid hardening furnace to prepare a melt spun strip with certain thickness;
a hydrogen explosion procedure, namely putting the slinger into a hydrogen explosion furnace, introducing hydrogen, and utilizing the reaction of rare earth and the hydrogen to break the slinger into coarse particles of 300-;
a jet milling process, wherein the coarse particles are crushed into fine powder by a jet crushing device, and the median particle size of the fine powder is 1-8 μm;
a powder distribution and film combination process, wherein the powder is subjected to powder distribution by the powder distribution method according to any one of claims 11 to 16, and the powder is filled into the die cavity to prepare an oriented compression die;
an orientation molding step of applying magnetic field orientation to the powder filled in the cavity and die-casting the powder into a molded body;
and a sintering step of sintering the molded body to obtain the NdFeB thin sheet magnet.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CN2020/105566 WO2022007057A1 (en) | 2020-07-10 | 2020-07-29 | Powder distribution device, powder distribution method therefor, and manufacturing method for ndfeb thin sheet magnet |
| CN202010664221.4A CN111968814A (en) | 2020-09-25 | 2020-09-25 | Powder distribution device and powder distribution method thereof, and manufacturing method of NdFeB series sheet magnet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010664221.4A CN111968814A (en) | 2020-09-25 | 2020-09-25 | Powder distribution device and powder distribution method thereof, and manufacturing method of NdFeB series sheet magnet |
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| CN111968814A true CN111968814A (en) | 2020-11-20 |
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| CN202010664221.4A Pending CN111968814A (en) | 2020-07-10 | 2020-09-25 | Powder distribution device and powder distribution method thereof, and manufacturing method of NdFeB series sheet magnet |
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| CN (1) | CN111968814A (en) |
| WO (1) | WO2022007057A1 (en) |
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| CN114589195A (en) * | 2022-04-01 | 2022-06-07 | 贵州师范大学 | Degradation treatment equipment and method for plastics in municipal refuse |
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