Powder distribution device and powder distribution method for preparing a thin sheet magnet

Abstract

The application relates to the technical field of wafer magnet processing, in particular to a powder distributing device and a powder distributing method for preparing a wafer magnet, wherein the powder distributing device comprises a mold, a powder feeding mechanism and a vibration mechanism; the mold comprises a mold body and a screen, the screen is arranged above the mold and connected with the mold body, magnetic powder is shaken off from the screen into the mold cavity of the mold body, the powder feeding mechanism is used for feeding the magnetic powder into the screen, and the vibration mechanism is connected with the mold body and used for driving the mold body to drive the screen to vibrate together. According to the technical scheme, the vibration mechanism is arranged to drive the mold body and the screen to vibrate together, so that the magnetic powder on the screen surface is uniformly shaken off into the mold body and filled to a preset density, the powder uniformity of single mold cavity or multiple mold cavities in the wafer magnet forming process is improved, and the performance and consistency of the finished product are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of processing of sheet magnets, and particularly relates to a powder distributing device and a powder distributing method for preparing sheet magnets. BACKGROUND

[0002] Nd2Fe14B, is a kind of artificial permanent magnet, and is also a permanent magnet with the strongest magnetic force so far, and the maximum magnetic energy product (BHmax) thereof is more than 10 times that of ferrite, and the magnetic force thereof can reach about 3500 Gauss in a naked magnetic state. The neodymium iron boron magnet has the advantages of high cost performance, small size, light weight, good mechanical properties and strong magnetism, and the advantages of such high energy density enable the neodymium iron boron permanent magnet material to be widely used in modern industry and electronic technology, and the neodymium iron boron magnet is praised as the king of magnetism in the magnetism field. Therefore, the preparation and expansion of the neodymium iron boron magnet have been the focus of continuous attention in the industry.

[0003] At present, the sintering method is commonly used in the industry to produce the neodymium iron boron permanent magnet material, and the specific steps include: melting the iron-based neodymium boron alloy raw material into an alloy liquid in an inert gas; the alloy liquid is rapidly cooled into an alloy sheet on a cooling roll through a casting mechanism and a tundish mechanism; then, the alloy sheet absorbs hydrogen to generate internal stress and is broken into coarse powder with a size of about 100 um; the coarse powder is formed into fine powder after air flow crushing; the fine powder is added with an organic solvent to improve the oxidation resistance and fluidity, and the magnetic powder is obtained, and then the magnetic powder is sequentially formed and sintered. The magnetic powder prepared by the above method has strong viscosity and poor fluidity, and in the magnetic powder forming process, the industry generally adopts the weighing method or the volume method to put a certain amount of magnetic powder into a larger size cavity; but in the preparation process of sheet-shaped magnets or thin-walled special-shaped magnets, a smaller size cavity needs to be used, which will cause a large difference in the filling powder (NdFeB magnetic powder) mass between different mold cavities, and finally affect the product performance and product consistency. SUMMARY

[0004] In order to overcome the above defects, the present application provides a powder distributing device and a powder distributing method for preparing sheet magnets, which are beneficial to improve the powder distribution uniformity in the sheet magnet forming process, thereby improving the performance and consistency of the sheet magnet finished product.

[0005] In a first aspect, the present application provides a powder distributing device for preparing sheet magnets, comprising:

[0006] A mold comprising a mold body and a screen, the screen being arranged above the mold and connected with the mold body, and the magnetic powder is shaken off from the screen into the mold cavity of the mold body;

[0007] A powder feeding mechanism for feeding the magnetic powder into the screen;

[0008] a vibrating mechanism connected with the mold body, used to drive the mold body to vibrate together with the screen.

[0009] In an embodiment, the vibrating mechanism comprises a driving member and a cam, the driving member, the cam and the mold are sequentially in transmission connection, the driving member is used to drive the cam to rotate, the rotation of the cam drives the mold to move up and down, so as to make the mold vibrate.

[0010] In an embodiment, the vibrating mechanism further comprises a mold frame, the mold frame comprises a base, a moving table and a plurality of spaced guide columns, the moving table is arranged above the base, the mold is arranged on the moving table, the lower end of the guide column is connected with the base, the upper end of the guide column extends through the moving table in the vertical direction, the guide column is in sliding connection with the moving table, the driving member is arranged on the base, and the cam is in transmission connection with the mold through the moving table.

[0011] In an embodiment, the vibrating mechanism further comprises a transmission block, the transmission block is arranged above the cam, the upper end of the transmission block is connected with the moving table, and the lower end of the transmission block is in abutment with the peripheral surface of the cam, the rotation of the cam drives the transmission block to move up and down together with the mold.

[0012] In an embodiment, a damping pad is arranged between the moving table and the driving member, the upper end of the damping pad is connected with the moving table, and the lower end of the damping pad is connected with the driving member; and / or,

[0013] An eccentric wheel follower is arranged below the moving table, the cam is in transmission connection with the eccentric wheel follower, and the eccentric wheel follower is connected with the moving table.

[0014] In an embodiment, the vibrating mechanism further comprises a pressing assembly, the pressing assembly comprises a pressing plate and a cylinder, the pressing plate is arranged above the mold, used to press the mold on the moving table, the cylinder is arranged on the mold frame, and the driving end of the cylinder is connected with the pressing plate, used to drive the pressing plate to move up and down.

[0015] In an embodiment, the vibrating frequency of the vibrating mechanism is 1-100 Hz; and / or,

[0016] The mesh of the screen is rectangular, the length is 4-20 mm, and the width is 1-7 mm; and / or,

[0017] The mold body is provided with a plurality of mold cavities, and the shape of the mold cavity comprises a cuboid, a cube, a cylinder, a circular ring or other irregular shapes.

[0018] In an embodiment, the powder feeding mechanism comprises:

[0019] A powder supply tank, the outlet of the lower end of which is provided with a first on-off valve to control the opening and closing of the outlet of the powder supply tank;

[0020] A first weighing hopper is arranged below the powder supply tank, the inlet of the upper end of which is connected to the outlet of the lower end of the powder supply tank, and the first weighing hopper is provided with a first weighing sensor, which is electrically connected to the first weighing hopper;

[0021] A second weighing hopper, the inlet of the upper end of which is connected to the outlet of the lower end of the first weighing hopper, and the outlet of the lower end of which is located above the screen to supply powder to the screen, is provided with a second on-off valve at the outlet of the lower end to control the opening and closing of the outlet of the second weighing hopper, and the second weighing hopper is provided with a second weighing sensor, which is electrically connected to the second weighing hopper;

[0022] A controller, the input and output ends of which are respectively electrically connected to the first weighing sensor and the first on-off valve, and the input and output ends of which are respectively electrically connected to the second weighing sensor and the second on-off valve, controls the opening and closing of the first on-off valve through the information output by the first weighing sensor, and controls the opening and closing of the second on-off valve through the information output by the second weighing sensor.

[0023] In an embodiment, the mold body is provided with a plurality of mold cavities, and the plurality of mold cavities are arranged in sequence along a first horizontal direction, and the second weighing hopper can move back and forth along the first horizontal direction; and / or,

[0024] The outlet of the second weighing hopper is provided with a disperser to disperse the magnetic powder before conveying it into the screen.

[0025] In a second aspect, the application provides a powder distribution method based on the powder distribution device as described above, which comprises the following steps:

[0026] The powder feeding mechanism pours a sufficient amount of magnetic powder into the screen;

[0027] The vibration mechanism is started, and the vibration mechanism drives the mold body and the screen to vibrate together, so that the screen shakes off the magnetic powder into the mold cavities of the mold body until the density of the magnetic powder in the mold cavities reaches a preset density value;

[0028] The surface of the magnetic powder in the mold cavities is scraped or flattened.

[0029] The technical scheme of the application drives the mold body and the screen mesh to vibrate together through the vibration mechanism, so that the magnetic powder on the screen mesh surface is evenly shaken off into the mold body and filled to a preset density, improving the uniformity of powder distribution in single cavity or multiple cavities during the forming process of the sheet magnet, and thus improving the performance and consistency of the finished product. In the application, under the transmission of the vibration mechanism, the amplitude and vibration frequency of each region of the screen mesh are the same, which makes the amount of magnetic powder shaken off by each region of the screen mesh basically consistent, that is, the amount of magnetic powder filled in each region of the cavity of the mold body is basically consistent, avoiding the uneven distribution of powder in each region of the mold body by the screen mesh; in addition, under the transmission of the vibration mechanism, the amplitude and vibration frequency of each region of the mold body are also consistent, which makes the density of the magnetic powder filled in each region of the cavity of the mold body remain consistent, avoiding the occurrence of local forming density being too large or too small; on the other hand, the mold body and the screen mesh vibrate together in a transmission manner, which can simplify the overall structure of the powder distribution device and save device cost. BRIEF DESCRIPTION OF DRAWINGS

[0030] The application will be further described below in combination with the drawings and embodiments.

[0031] Figure 1 The structure schematic view of the powder distribution device in an embodiment of the application is shown in the figure.

[0032] Figure 2 The structure schematic view of the vibration mechanism in the powder distribution device is shown in the figure. Figure 1

[0033] Figure 3 The front view of the powder distribution device is shown in the figure. Figure 2

[0034] Figure 4 The structure schematic view of the vibration mechanism in another embodiment of the application is shown in the figure.

[0035] Reference signs:

[0036] Reference Name Reference Name 100 Powder distribution device 110 Mold 111 Mold body 1111 Mold cavity 112 Screen 120 Vibration mechanism 121 Driving piece 122 Cam 123 Transmission block 124 Damping pad 125 Eccentric wheel follower 126 Mold frame 1261 Base 1262 Moving table 1263 Guide column 127 Pressing assembly 1271 Pressing plate 1272 Air cylinder 130 Powder feeding mechanism 131 Powder supply tank 132 First on-off valve 133 First weighing hopper 134 First weighing sensor 135 Vibration platform 136 Second weighing hopper 137 Second weighing sensor 138 Second on-off valve 139 Knocking air cylinder DETAILED DESCRIPTION

[0037] In order to better understand the technical scheme of the application, the embodiments of the application will be described in detail below in combination with the drawings.

[0038] It should be clear that the described embodiments are only part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the application.

[0039] ​​The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the description of the application and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0040] It should be understood that the term "and / or" as used herein merely describes associated objects, which can exist in three relationships, for example, A and / or B can represent three cases: A exists alone, A and B exist together, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the front and rear associated objects.

[0041] The application provides a powder distribution device 100 for preparing a thin sheet magnet.

[0042] Referring to Figure 1 and Figure 2 In the embodiment of the application, the powder distribution device 100 comprises a mold 110, a powder feeding mechanism 130 and a vibration mechanism 120. The mold 110 comprises a mold body 111 and a screen 112, the screen 112 is arranged above the mold 110 and connected with the mold body 111, and the magnetic powder is shaken through the screen 112 and falls into the mold cavity 1111 of the mold body 111. The powder feeding mechanism 130 is used to feed the magnetic powder into the screen 112. The vibration mechanism 120 is connected with the mold body 111 and used to drive the mold body 111 to vibrate together with the screen 112. The vibration mechanism 120 can be a piston vibrator, a pneumatic hammer vibrator or other general mechanical vibrator.

[0043] The technical scheme of the present application drives the mold body 111 and the screen 112 to vibrate together through the vibration mechanism 120, so that the magnetic powder on the screen 112 is evenly shaken off and filled to a preset density in the mold body 111, improving the uniformity of powder distribution in single or multiple mold cavities during the sheet magnet forming process, and thus improving the performance and consistency of the finished product. In the present application, under the transmission of the vibration mechanism 120, the amplitude and vibration frequency of each region of the screen 112 are the same, which makes the amount of magnetic powder shaken off by each region of the screen 112 basically consistent, i.e. the amount of magnetic powder filled in each region of the mold cavity 1111 of the mold body 111 is basically consistent, avoiding the uneven distribution of powder in each region of the mold body 111 by the screen 112; in addition, under the transmission of the vibration mechanism 120, the amplitude and vibration frequency of each region of the mold body 111 are also consistent, which makes the density of the magnetic powder filled in each region of the mold cavity 1111 of the mold body 111 remain consistent, avoiding the occurrence of local forming density being too large or too small; on the other hand, the mold body 111 and the screen 112 vibrate together in a transmission manner, which can simplify the overall structure of the powder distribution device 100 and save device cost.

[0044] In an embodiment, the vibration frequency of the vibration mechanism 120 is 1-100Hz, i.e. the vibration frequency of the vibration mechanism 120 is 1Hz, 20Hz, 40Hz, 60Hz, 80Hz, 100Hz or any value therebetween, within this vibration frequency range, the screen 112 can more stably and uniformly distribute powder into the mold cavity 1111 of the mold body 111.

[0045] The screen 112 includes a screen surface and a screen frame surrounding the screen surface, the screen holes of the screen surface can be rectangular, circular, elliptical, triangular, rectangular or other polygonal shapes, which are not specifically limited in the present application. In a specific embodiment, the screen holes of the screen surface are rectangular or square, the length is 4-20mm, specifically 4mm, 10mm, 15mm, 20mm or any value therebetween, the width is 1-7mm, specifically 1mm, 3mm, 5mm, 7mm or any value therebetween; preferably, the screen holes of the screen surface are rectangular grids with a length of 9mm and a width of 4mm. Of course, those skilled in the art can select appropriate size and shape of the grid according to the size, agglomeration of the magnetic powder and the size of the mold cavity 1111 of the mold body 111, which is not particularly limited.

[0046] The number of the mold cavities 1111 of the mold body 111 can be one or multiple. In an embodiment, the mold body 111 is provided with multiple mold cavities 1111, which are arranged in sequence along the length direction of the mold body 111. The shape of the mold cavities 1111 includes a cuboid, a cube, a cylinder, a circular ring, or other irregular shapes. It should be noted that the shapes of different mold cavities 1111 can be the same or different. Those skilled in the art can design the specific shape of the mold cavities 1111 according to actual needs, which is not specifically limited in the present application.

[0047] In an embodiment, the vibration mechanism 120 includes a driving member 121 and a cam 122, which are sequentially connected in transmission with the mold 110. The driving member 121 is used to drive the rotation of the cam 122, and the rotation of the cam 122 drives the mold 110 to move up and down to vibrate. Specifically, the driving member 121 can be a motor or other rotary driving member 121. The peripheral surface of the cam 122 is curved or has curved grooves. In a specific embodiment, the cam 122 has multiple concave portions and multiple convex portions, which are arranged alternately along the circumferential direction of the cam 122. During the rotation of the cam 122 driven by the driving member 121, the mold body 111 and the screen 112 gradually change from the abutment of the convex portions of the cam 122 to the abutment of the concave portions of the cam 122, and then the mold body 111 and the screen 112 gradually change from the abutment of the concave portions of the cam 122 to the abutment of the convex portions of the cam 122. During the rotation of the cam 122, the mold body 111 and the screen 112 alternately descend and ascend. Since the distance of the descent and the ascent is relatively short, the switching time of the descent and the ascent is also relatively short, so that the mold body 111 and the screen 112 finally present a vibration state.

[0048] In an embodiment, the vibrating mechanism 120 further comprises a mold frame 126, the mold frame 126 comprising a base 1261, a moving table 1262 arranged above the base 1261, a plurality of spaced-apart guide columns 1263, the lower ends of the guide columns 1263 being connected with the base 1261, the upper ends of the guide columns 1263 extending in the vertical direction and penetrating through the moving table 1262, the guide columns 1263 being in sliding connection with the moving table 1262, the driving member 121 being arranged on the base 1261, and the cam 122 being in driving connection with the mold 110 through the moving table 1262.

[0049] On the basis of the above-mentioned embodiment, in a specific embodiment, the number of the guide columns 1263 is two, the lower ends of the two guide columns 1263 being fixedly connected with the left and right ends of the base 1261 respectively, the driving member 121 being fixedly arranged on the base 1261, the cam 122 being arranged at the front end of the driving member 121, the left and right ends of the moving table 1262 being slidably sleeved on the two guide columns 1263 respectively, the peripheral surface of the upper end of the cam 122 being in movable connection with the moving table 1262, and in the process of driving the cam 122 to rotate by the driving member 121, the moving table 1262 moves up and down along the guide columns 1263 together, thereby driving the mold body 111 and the screen 112 to vibrate up and down. In this specific embodiment, the mold body 111 and the screen 112 move up and down together with the moving table 1262 along the guide columns 1263, which avoids the instability of the vibration amplitude or the vibration frequency of the mold body 111 and the screen 112 caused by the deviation of the moving direction during the moving process.

[0050] In another specific embodiment, in order to facilitate the driving connection between the cam 122 and the moving table 1262, the vibrating mechanism 120 further comprises a transmission block 123, the transmission block 123 being arranged above the cam 122, the upper end of the transmission block 123 being connected with the moving table 1262, and the lower end of the transmission block 123 being in abutment with the peripheral surface of the cam 122, the rotation of the cam 122 driving the transmission block 123 to move up and down together with the mold 110.

[0051] To avoid or reduce the upward jump of the moving table 1262 due to the falling collision with the driving member 121 below, further, a damping pad 124 is arranged between the moving table 1262 and the driving member 121, the upper end of the damping pad 124 is connected with the moving table 1262, and the lower end is connected with the driving member 121; and / or, an eccentric wheel follower 125 is arranged below the moving table 1262, the peripheral surface of the eccentric wheel follower 125 abuts against the lower side of the moving table 1262. In a specific embodiment, the upper end of the eccentric wheel follower 125 is connected with the lower end of the moving table 1262 through the damping pad 124, the lower end of the eccentric wheel follower 125 is provided with an opening, one end of the cam 122 is connected with the driving member 121, and the other end penetrates through the opening and abuts against the lower end of the transmission block 123, part of the peripheral surface of the cam 122 abuts against the inner wall of the lower end of the opening, and in the process of lowering the moving table 1262, the damping pad 124 and the eccentric wheel follower 125 together reduce the upward jump of the moving table 1262 due to the falling collision with the driving member 121 below.

[0052] In an embodiment, the vibration mechanism 120 further comprises a pressing assembly 127, the pressing assembly 127 comprises a pressing plate 1271 and a pneumatic cylinder 1272, the pressing plate 1271 is arranged above the mold 110 to press the mold 110 on the moving table 1262, and the pneumatic cylinder 1272 is arranged on the mold frame 126, and the driving end thereof is connected with the pressing plate 1271 to drive the pressing plate 1271 to move up and down. Specifically, the pneumatic cylinder 1272 is fixedly arranged above the mold 110, the pushing rod tail end of the pneumatic cylinder 1272 is fixedly connected with the pressing plate 1271, the pushing rod of the pneumatic cylinder 1272 is elongated downward, the pressing plate 1271 of the pneumatic cylinder 1272 moves towards the mold 110 until the mold 110 is pressed on the moving table 1262, the pushing rod of the pneumatic cylinder 1272 is retracted upward, and the pressing plate 1271 moves upward so that the mold 110 can be taken off from the moving table 1262. In the process of driving the cam 122 to rotate by the driving member 121, the pressing assembly 127 moves up and down together with the moving table 1262 and the mold 110.

[0053] In an embodiment, the powder feeding mechanism 130 comprises a powder tank 131, a first weighing hopper 133, a second weighing hopper 136 and a controller; the outlet at the lower end of the powder tank 131 is provided with a first on-off valve 132 to control the opening and closing of the outlet of the powder tank 131; the first weighing hopper 133 is arranged below the powder tank 131, the inlet at the upper end of the first weighing hopper 133 is connected to the outlet at the lower end of the powder tank 131, the first weighing hopper 133 is provided with a first weighing sensor 134, and the first weighing sensor 134 is electrically connected to the first weighing hopper 133; the inlet at the upper end of the second weighing hopper 136 is connected to the outlet at the lower end of the first weighing hopper 133, the outlet at the lower end of the second weighing hopper 136 is located above the screen 112 to feed powder to the screen 112, the outlet at the lower end of the second weighing hopper 136 is provided with a second on-off valve 138 to control the opening and closing of the outlet of the second weighing hopper 136, the second weighing hopper 136 is provided with a second weighing sensor 137, and the second weighing sensor 137 is electrically connected to the second weighing hopper 136; the input and output of the controller are electrically connected to the first weighing sensor 134 and the first on-off valve 132, respectively, and the input and output of the controller are electrically connected to the second weighing sensor 137 and the second on-off valve 138, respectively, the controller controls the opening and closing of the first on-off valve 132 through the information output by the first weighing sensor 134, and controls the opening and closing of the second on-off valve 138 through the information output by the second weighing sensor 137. The first on-off valve 132 and the second on-off valve 138 can be selected from valves such as pneumatic valves and electromagnetic valves, and are not particularly limited.

[0054] In detail, the upper end of the powder supply tank 131 is provided with a powder injection opening, and a knocking cylinder 139 is connected to the outer wall of the powder supply tank 131, which is used to knock the powder supply tank 131 to knock the magnetic powder in the powder supply tank 131 into the first weighing hopper 133. The outlet at the lower end of the first weighing hopper 133 is provided with a vibrating platform 135, and the magnetic powder in the first weighing hopper 133 is vibrated into the second weighing hopper 136 through the vibrating platform 135. During operation, the operator injects the magnetic powder into the powder supply tank 131 from the powder injection opening, opens the first on-off valve 132, and the magnetic powder flows from the outlet at the lower end of the powder supply tank 131 into the first weighing hopper 133. When the first weighing sensor 134 measures that the amount of magnetic powder in the first weighing hopper 133 reaches a first expected weight, the controller controls the first on-off valve 132 to be closed and controls the vibrating platform 135 to be started to shake the magnetic powder in the first weighing hopper 133 into the second weighing hopper 136. When the second weighing sensor 137 measures that the weight of the magnetic powder in the second weighing hopper 136 reaches a second expected weight, the controller controls the vibrating platform 135 to be closed, and the magnetic powder in the first weighing hopper 133 stops falling into the second weighing hopper 136. Then, the controller controls the second on-off valve 138 to be opened, and the second weighing hopper 136 distributes the powder to the screen 112. When the second weighing sensor 137 measures that the amount of powder distributed by the second weighing hopper 136 to the screen 112 reaches a third expected weight, the controller controls the second on-off valve 138 to be closed.

[0055] In the above embodiment, the outlet of the second weighing hopper 136 can be a hollow structure, or further, the outlet of the second weighing hopper 136 is provided with a disperser to disperse the magnetic powder before conveying it into the screen 112. Specifically, the disperser can be a screw, a paddle or other structure that can disperse the magnetic powder.

[0056] The plurality of mold cavities 1111 of the mold body 111 are arranged in sequence along a first horizontal direction. In order to improve the uniformity of powder distribution of the powder distribution mechanism 130, the second weighing hopper 136 can move back and forth along the first horizontal direction. During operation, the second weighing hopper 136 can uniformly distribute powder to each area of the screen 112 by moving back and forth along the first horizontal direction, thereby improving the uniformity of powder distribution of the screen 112 to the plurality of mold cavities 1111.

[0057] The application also proposes a powder distribution method based on the powder distribution device 100 as described above, which comprises the following steps:

[0058] The powder feeding mechanism 130 pours a sufficient amount of magnetic powder into the screen 112, that is, the amount of magnetic powder poured by the powder feeding mechanism 130 into the screen 112 is not less than the expected amount of magnetic powder filled in the mold body 111, so as to improve the powder distribution uniformity as much as possible, especially for the mold body 111 with multiple mold cavities 1111, the powder distribution quality difference of each mold cavity 1111 can be reduced.

[0059] The vibration mechanism 120 is started to drive the mold body 111 and the screen 112 to vibrate together, so that the screen 112 shakes off the magnetic powder into the mold cavity 1111 of the mold body 111, until the density of the magnetic powder in the mold cavity 1111 reaches a preset density value.

[0060] The surface of the magnetic powder in the mold cavity 1111 is scraped or flattened to eliminate the unevenness of the upper surface of the magnetic powder in the mold cavity 1111 due to the difference in the pre-charge loose density of the magnetic powder, the difference in the direction and size of the vibration force, and other reasons. Specifically, the surface of the magnetic powder can be scraped flat by a scraper or a harrow, or the surface of the magnetic powder can be moved flat by a mesh screen with a size suitable.

[0061] The technical scheme of the present application can uniformly shake off the magnetic powder on the screen 112 into the mold body 111 by the vibration mechanism 120 and fill the magnetic powder to a preset density, thereby improving the powder distribution uniformity of a single mold cavity or multiple mold cavities in the process of forming a thin sheet magnet, and further improving the performance and consistency of the finished product.

[0062] In the embodiment of the present application, the magnetic powder is NdFeB magnetic powder, and the particle size of the powder is 1-10 um, specifically 1 um, 4 um, 8 um, 10 um or any value therebetween, and the particle size distribution D90 / D10 is less than or equal to 7.

[0063] In the embodiment of the present application, the magnetic powder further contains an additive, and the additive includes a combination of one or more of methyl stearate, monochlorobenzene, tributyl borate, methyl laurate, and n-hexane. The mixing equipment used can be a three-dimensional mixer or a V-type mixer.

[0064] In the embodiment of the present application, the preset density value is 3.2-4.4 g / cm3, specifically 3.2 g / cm3, 3.6 g / cm3, 3.8 g / cm3, 4 g / cm3, 4.4 g / cm3 or any value therebetween.

[0065] Performance test

[0066] The NdFeB magnet is prepared by the powder distribution method of the present application, and the preparation process is as follows:

[0067] Example 1-3: square magnets with the size of 40mm*20mm*9.5mm were prepared, 25 magnets were prepared according to 25 cavities of the mold body, and the mass distribution of the 25 magnets is shown in Table 1 (range = maximum - minimum, fluctuation = range / average / 2):

[0068]

[0069]

[0070] From the above Table 1, the difference between the maximum mass and the minimum mass of the magnets in Examples 1-3 is 1.39g, 1.33g and 1.05g respectively, and the mass fluctuation is ±1.7%, ±2.2% and ±1.5% respectively; that is, in the same batch of molded magnets, the mass fluctuation of the magnets prepared in different cavities is small, and the mass distribution uniformity of the magnetic powder in each cavity is very high.

[0071] Example 3-6: hollow ring magnets were prepared, 16 magnets were prepared according to 16 cavities of the mold body, and the mass distribution of the 16 magnets is shown in Table 2 (range = maximum - minimum, fluctuation = range / average / 2):

[0072]

[0073]

[0074] From the above Table 2, the difference between the maximum mass and the minimum mass of the magnets in Examples 4-6 is 0.055g, 0.049g and 0.049g respectively, and the mass fluctuation is ±3.2%, ±2.9% and ±2.8% respectively; that is, in the same batch of molded magnets, the mass distribution uniformity of the magnetic powder in each cavity is very high. Compared with Example 1-3, the mass fluctuation of the ring magnets prepared in Example 4-6 is slightly larger, mainly because the ring magnet is a thin-walled part, and it is difficult to fill the magnetic powder, resulting in large mass fluctuation.

[0075] The above is only a preferred embodiment of the present application, and is not intended to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. An attrition powder apparatus for preparing a flake magnet, characterized by, The application relates to a magnetic powder vibrating and feeding device. The device comprises a mold and a powder feeding mechanism. The mold comprises a mold body and a screen, the screen is arranged above the mold and connected with the mold body, and magnetic powder is shaken into the mold cavity of the mold body through the screen. The powder feeding mechanism comprises a powder supply tank, a first weighing hopper, a second weighing hopper, a controller, a driving member and a cam. The lower end of the powder supply tank is provided with a first switch valve to control the opening and closing of the outlet of the powder supply tank. The upper end of the first weighing hopper is connected with the lower end of the powder supply tank, and the first weighing hopper is provided with a first weighing sensor. The upper end of the second weighing hopper is connected with the lower end of the first weighing hopper, and the lower end of the second weighing hopper is arranged above the screen to feed the screen. The lower end of the second weighing hopper is provided with a second switch valve to control the opening and closing of the outlet of the second weighing hopper. The controller is electrically connected with the first weighing sensor and the first switch valve, and is electrically connected with the second weighing sensor and the second switch valve.

2. The powder distribution device of claim 1, wherein The controller controls the opening and closing of the first switch valve through the information output by the first weighing sensor, and controls the opening and closing of the second switch valve through the information output by the second weighing sensor.

3. The powder distribution device of claim 2, wherein The vibrating mechanism comprises a driving member and a cam, the driving member, the cam and the mold are sequentially connected in transmission, the driving member is used to drive the cam to rotate, the rotation of the cam drives the mold to move up and down to vibrate.

4. The powder distribution device of claim 3, wherein The vibrating mechanism further comprises a mold frame, the mold frame comprises a base, a moving table and a plurality of interval arranged guide columns, the moving table is arranged above the base, the mold is arranged on the moving table, the lower end of the guide column is connected with the base, the upper end of the guide column extends in the vertical direction and is arranged in the moving table, the guide column is slidably connected with the moving table, the driving member is arranged on the base, and the cam is connected with the mold in transmission through the moving table.

5. The powder distribution device of claim 4, wherein, The vibrating mechanism further comprises a transmission block, the transmission block is arranged above the cam, the upper end of the transmission block is connected with the moving table, and the lower end of the transmission block is abutted with the peripheral surface of the cam. The rotation of the cam drives the transmission block to move up and down with the mold. A damping pad is arranged between the moving table and the driving member, the upper end of the damping pad is connected with the moving table, and the lower end of the damping pad is connected with the driving member. An eccentric wheel follower is arranged below the moving table, the cam is connected with the eccentric wheel follower in transmission, and the eccentric wheel follower is connected with the moving table.

6. The powder distribution device of claim 3, wherein The vibrating mechanism further comprises a pressing assembly, which comprises a pressing plate and a pneumatic cylinder, the pressing plate is arranged above the mold to press the mold on the moving table, the pneumatic cylinder is arranged on the mold frame, and the driving end of the pneumatic cylinder is connected with the pressing plate to drive the pressing plate to move up and down.

7. The cloth powdering device according to any one of claims 1 to 6, wherein The vibrating frequency of the vibrating mechanism is 1-100 Hz; and / or, The mesh of the screen is rectangular, with a length of 4-20 mm and a width of 1-7 mm; and / or, The mold body is provided with a plurality of mold cavities, and the shape of the mold cavity includes a cuboid, a cube, a cylinder, a circular ring body or other irregular shapes.

8. The powder distribution device of claim 1, wherein, The mold body is provided with a plurality of mold cavities, and the plurality of mold cavities are arranged in sequence along a first horizontal direction, and the second weighing hopper can move back and forth along the first horizontal direction; and / or, The outlet of the second weighing hopper is provided with a disperser to disperse the magnetic powder before conveying it into the screen.

9. A powder spreading method based on the powder spreading device according to any one of claims 1 to 8, characterized by, The method comprises the following steps: The powder feeding mechanism pours a sufficient amount of magnetic powder into the screen; Start the vibrating mechanism, the vibrating mechanism drives the mold body and the screen to vibrate together, so that the screen shakes off the magnetic powder into the mold cavity of the mold body, until the density of the magnetic powder in the mold cavity of the mold body reaches a preset density value; The surface of the magnetic powder in the mold cavity of the mold body is scraped or flattened. The surface of the magnetic powder in the mold cavity of the mold body is scraped or flattened.

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