Powder distribution device for preparing thin magnet and powder distribution method

Abstract

The present application relates to the technical field of thin magnet processing, and in particular to a powder distribution device for preparing a thin magnet and a powder distribution method. The powder distribution 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 at the upper part of the mold and is connected to the mold body, and magnetic powder is sifted through the screen and falls into mold cavities of the mold body; the powder feeding mechanism is used for delivering the magnetic powder into the screen; and the vibration mechanism is connected to the mold body and is used for driving the mold body to drive the screen to vibrate together. According to the technical solution of the present application, by providing the vibration mechanism to drive the mold body and the screen to vibrate together, magnetic powder on the screen surface of the screen is uniformly sifted and falls into the mold body and is loaded to a preset density, and thus, the powder distribution uniformity in a single mold cavity or multiple mold cavities in a thin magnet forming process is improved, thereby improving the performance and consistency of finished products.

Description

Powder distribution device and powder distribution method for preparing thin-sheet magnets Technical Field

[0001] The present application relates to the technical field of processing thin-sheet magnets, and in particular to a powder distribution device and a powder distribution method for preparing thin-sheet magnets. Background Art

[0002] Neodymium iron boron (NdFeB) magnets, also known as neodymium magnets, have the chemical formula Nd2Fe14B. They are man-made permanent magnets and currently possess the strongest magnetic force. Their maximum magnetic energy product (BHmax) is over 10 times higher than that of ferrites, and in their bare state, their magnetic force can reach approximately 3500 gauss. NdFeB magnets offer advantages such as high cost-effectiveness, compact size, light weight, excellent mechanical properties, and strong magnetic properties. This high energy density has led to their widespread application in modern industry and electronics, earning them the nickname "King of Magnets" in the magnetics community. Consequently, the preparation and expansion of NdFeB magnets has been a constant focus of industry attention.

[0003] Currently, the industry often uses the sintering method to produce NdFeB permanent magnet materials. The specific steps include: smelting iron-based NdFeB alloy raw materials into alloy liquid in an inert gas; the alloy liquid is then rapidly cooled on a cooling roller through a casting mechanism and a tundish mechanism to form alloy flakes; the alloy flakes then absorb hydrogen to generate internal stress and break into coarse powder of about 100 μm; the coarse powder is then pulverized by air flow to form fine powder; an organic solvent is added to the fine powder to improve its oxidation resistance and fluidity to obtain magnetic powder, which is then molded and sintered in sequence. The magnetic powder prepared by the above method has strong viscosity and poor fluidity. During the magnetic powder molding process, the industry generally uses weighing or volumetric methods to take a certain amount of magnetic powder and place it into a larger mold cavity; however, in the preparation of thin-sheet magnets or thin-walled special-shaped magnets, a smaller mold cavity is required, which will result in large differences in the quality of the filling powder (NdFeB magnetic powder) between different mold cavities, ultimately affecting product performance and product consistency. Technical issues

[0004] In the preparation process of thin-sheet magnets or thin-walled special-shaped magnets, a smaller cavity size is required, which will lead to large differences in the quality of the filling powder (NdFeB magnetic powder) between different mold cavities, ultimately affecting product performance and product consistency. Technical Solutions

[0005] In a first aspect, the present application proposes a powder distribution device for preparing thin-sheet magnets, comprising:

[0006] The mold includes a mold body and a screen, wherein the screen is arranged above the mold and connected to the mold body, and the magnetic powder is shaken off through the screen into the mold cavity of the mold body;

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

[0008] The vibration mechanism is connected to the mold body and is used to drive the mold body to drive the screen to vibrate together.

[0009] In one embodiment, the vibration mechanism includes a driving member and a cam. The driving member, the cam, and the mold are sequentially connected in a transmission manner. The driving member is used to drive the cam to rotate. The rotation of the cam drives the mold to move up and down, thereby causing the mold to vibrate.

[0010] In one embodiment, the vibration mechanism also includes a mold frame, which includes a base, a movable platform and a plurality of guide pillars arranged at intervals. The movable platform is arranged above the base, and the mold is arranged on the movable platform. The lower end of the guide pillar is connected to the base, and the upper end is passed through the movable platform and extends in a vertical direction. The guide pillar is slidably connected to the movable platform, the driving member is arranged on the base, and the cam is connected to the mold through the movable platform.

[0011] In one embodiment, the vibration mechanism further includes a transmission block, which is arranged above the cam, the upper end of the transmission block is connected to the movable platform, and the lower end of the transmission block abuts against the circumferential surface of the cam, and the rotation of the cam drives the transmission block to move up and down with the mold.

[0012] In one embodiment, a shock-absorbing pad is provided between the moving platform and the driving member, wherein the upper end of the shock-absorbing pad is connected to the moving platform and the lower end is connected to the driving member; and / or,

[0013] An eccentric follower block is provided below the movable platform, the cam is in transmission connection with the eccentric follower block, and the eccentric follower block is connected to the movable platform.

[0014] In one embodiment, the vibration mechanism also includes a pressing component, which includes a pressing plate and a cylinder. The pressing plate is arranged above the mold to press the mold on the movable platform. The cylinder is arranged on the mold frame, and its driving end is connected to the pressing plate to drive the pressing plate to move up and down.

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

[0016] The mesh of the screen is rectangular, 4 to 20 mm long and 1 to 7 mm wide; and / or,

[0017] The mold body is provided with a plurality of mold cavities, and the shapes of the mold cavities include rectangular parallelepiped, cube, cylinder, torus or other irregular shapes.

[0018] In one embodiment, the powder feeding mechanism includes:

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

[0020] a first weighing hopper, disposed below the powder supply tank, with an inlet at its upper end connected to an outlet at the lower end of the powder supply tank; a first weighing sensor disposed on the first weighing hopper, the first weighing sensor being electrically connected to the first weighing hopper;

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

[0022] A controller, whose input and output are electrically connected to the first weighing sensor and the first switch valve respectively, and whose input and output are electrically connected to the second weighing sensor and the second switch valve respectively, 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.

[0023] In one embodiment, the mold body is provided with a plurality of mold cavities, the plurality of mold cavities are sequentially arranged 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 and then transport it to the screen.

[0025] In a second aspect, the present application proposes a powder distribution method based on the above-mentioned powder distribution device, comprising the following steps:

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

[0027] Starting the vibration mechanism, the vibration mechanism drives the mold body and the screen to vibrate together, so that the screen shakes 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;

[0028] Scrape or flatten the surface of the magnetic powder in the mold cavity of the mold body. Beneficial effects

[0029] In the technical solution of the present application, a vibration mechanism is set to drive the mold body and the screen to vibrate together, so that the magnetic powder on the screen surface is evenly shaken off in the mold body and filled to a preset density, thereby improving the powder distribution uniformity of a single mold cavity or multiple mold cavities during the thin-film magnet molding process, thereby improving the performance and consistency of the finished product. In the present application, under the transmission of the vibration mechanism, the amplitude and vibration frequency of each area of ​​the screen are the same, which makes the amount of magnetic powder shaken off by each area of ​​the screen basically consistent, that is, the amount of magnetic powder filled in each area of ​​the mold cavity of the mold body is basically consistent, avoiding the uneven distribution of powder by the screen to each area of ​​the mold body; in addition, under the transmission of the vibration mechanism, the amplitude and vibration frequency of each area of ​​the mold body are also consistent, which makes the density of the magnetic powder filled in each area of ​​the mold cavity of the mold body consistent, avoiding the occurrence of excessive or insufficient local molding density; on the other hand, the mold body and the screen vibrate together in a transmission manner, which can simplify the overall structure of the powder distribution device and save device costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below with reference to the accompanying drawings and examples.

[0031] FIG1 is a schematic structural diagram of a powder distribution device according to an embodiment of the present invention;

[0032] FIG2 is a schematic structural diagram of the vibration mechanism in FIG1 ;

[0033] Figure 3 is a front view of Figure 2;

[0034] FIG4 is a schematic structural diagram of the vibration mechanism of the present application in another embodiment.

[0035] Reference numerals:

[0036] Best Mode for Carrying Out the Invention

[0037] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0038] It should be understood that the embodiments described are only a portion of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0039] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "an", "the" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0040] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

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

[0042] Please refer to Figures 1 and 2. In the embodiment of the present application, the powder distribution device 100 includes a mold 110, a powder feeding mechanism 130 and a vibration mechanism 120. The mold 110 includes a mold body 111 and a screen 112. The screen 112 is arranged above the mold 110 and connected to the mold body 111. The magnetic powder is shaken into the mold cavity 1111 of the mold body 111 through the screen 112; the powder feeding mechanism 130 is used to transport the magnetic powder to the screen 112; the vibration mechanism 120 is connected to the mold body 111 to drive the mold body 111 to vibrate together with the screen 112. The vibration mechanism 120 can be a piston vibrator, an air hammer vibrator or other universal mechanical vibrator.

[0043] The technical solution of the present application drives the mold body 111 and the screen 112 to vibrate together by setting a vibration mechanism 120, so that the magnetic powder on the mesh surface of the screen 112 is evenly shaken off into the mold body 111 and filled to a preset density, thereby improving the powder distribution uniformity of a single mold cavity or multiple mold cavities during the thin-film magnet forming process, thereby 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 area of ​​the screen 112 are the same, which makes the amount of magnetic powder shaken off by each area of ​​the screen 112 basically the same, that is, the amount of magnetic powder filled in each area of ​​the mold cavity 1111 of the mold body 111 is basically the same, avoiding the uneven distribution of powder by the screen 112 to each area of ​​the mold body 111; in addition, under the transmission of the vibration mechanism 120, the amplitude and vibration frequency of each area of ​​the mold body 111 are also consistent, which makes the density of the magnetic powder filled in each area of ​​the mold cavity 1111 of the mold body 111 consistent, avoiding the occurrence of local molding density that is too large or too small; on the other hand, the mold body 111 and the screen 112 vibrate together using a transmission method, which can simplify the overall structure of the powder distribution device 100 and save device costs.

[0044] In one embodiment, the vibration frequency of the vibration mechanism 120 is 1-100 Hz, that is, the vibration frequency of the vibration mechanism 120 is 1 Hz, 20 Hz, 40 Hz, 60 Hz, 80 Hz, 100 Hz or any value therebetween. Within this vibration frequency range, the screen 112 can distribute powder in the mold cavity 1111 of the mold body 111 more stably and evenly.

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

[0046] The number of mold cavities 1111 of the mold body 111 can be one or more. In one embodiment, the mold body 111 is provided with a plurality of mold cavities 1111, and the plurality of mold cavities 1111 are arranged in sequence along the length direction of the mold body 111. The shapes of the mold cavities 1111 include rectangular prisms, cubes, cylinders, torus 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 cavity 1111 according to actual needs, and this application does not make specific limitations on this.

[0047] In one embodiment, the vibration mechanism 120 includes a driving member 121 and a cam 122. The driving member 121, the cam 122, and the mold 110 are sequentially connected in a transmission manner. The driving member 121 is used to drive the cam 122 to rotate. The rotation of the cam 122 drives the mold 110 to move back and forth up and down, thereby causing the mold 110 to vibrate. Specifically, the driving member 121 can be a motor or other rotating driving member 121. The circumference of the cam 122 is curved or has a curved groove formed on its circumference. In a specific embodiment, the cam 122 has a plurality of concave portions and a plurality of convex portions, and the concave portions and the convex portions are alternately arranged along the circumference of the cam 122. During the process of the driving member 121 driving the cam 122 to rotate, the upper end of the cam 122 gradually changes from its convex portion abutting against the mold body 111 to its concave portion abutting against the mold body 111. The mold body 111 and the screen 112 move along with the cam. 122 descends with the rotation of the cam 122; in the process that the upper end of the cam 122 gradually changes from the concave part thereof abutting against the mold body 111 to the convex part abutting against the mold body 111, the mold body 111 and the screen 112 rise with the rotation of the cam 122; in the process that the driving member 121 drives the cam 122 to rotate, the mold body 111 and the screen 112 alternately descend and ascend, and since the descending and ascending distances are short, the switching time between the two is also short, so that the mold body 111 and the screen 112 finally present a vibrating state.

[0048] In one embodiment, the vibration mechanism 120 also includes a mold frame 126, and the mold frame 126 includes a base 1261, a movable platform 1262 and a plurality of guide pillars 1263 arranged at intervals. The movable platform 1262 is arranged above the base 1261, and the mold 110 is arranged on the movable platform 1262. The lower end of the guide pillar 1263 is connected to the base 1261, and the upper end is passed through the movable platform 1262 and extends in a vertical direction. The guide pillar 1263 is slidably connected to the movable platform 1262, and the driving member 121 is arranged on the base 1261. The cam 122 is transmission-connected to the mold 110 through the movable platform 1262.

[0049] On the basis of the above embodiments, in a specific embodiment, the number of the guide pillars 1263 is two, and the lower ends of the two guide pillars 1263 are fixedly connected to the left and right ends of the base 1261 respectively, the driving member 121 is fixedly set on the base 1261, the cam 122 is set at the front end of the driving member 121, and the left and right ends of the movable platform 1262 can be slidably mounted on the two guide pillars 1263 respectively, and the circumferential surface of the upper end of the cam 122 is movably connected to the movable platform 1262. In the process of the driving member 121 driving the cam 122 to rotate, the movable platform 1262 moves back and forth along the guide pillars 1263, 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 movable platform 1262 along the guide column 1263, thereby avoiding the occurrence of unstable vibration amplitude or vibration frequency of the mold body 111 and the screen 112 due to deviation in the moving direction during movement.

[0050] In another specific embodiment, in order to facilitate the transmission connection between the cam 122 and the movable platform 1262, the vibration mechanism 120 also includes a transmission block 123, which is arranged above the cam 122, the upper end of the transmission block 123 is connected to the movable platform 1262, and the lower end of the transmission block 123 is in contact with the circumferential surface of the cam 122. The rotation of the cam 122 drives the transmission block 123 to move up and down with the mold 110.

[0051] In order to avoid or reduce the upward jumping of the moving platform 1262 due to falling and colliding with the driving member 121 below it, a shock-absorbing pad 124 is further provided between the moving platform 1262 and the driving member 121, and the upper end of the shock-absorbing pad 124 is connected to the moving platform 1262, and the lower end is connected to the driving member 121; and / or, an eccentric follower block 125 is provided below the moving platform 1262, and the peripheral surface of the eccentric follower block 125 abuts against the bottom of the moving platform 1262. In a specific embodiment, the upper end of the eccentric follower block 125 is connected to the lower end of the moving platform 1262 through the shock-absorbing pad 124, and the lower end of the eccentric follower block 125 is provided with an opening. One end of the cam 122 is connected to the driving member 121, and the other end passes through the opening and abuts against the lower end of the transmission block 123. Part of the circumference of the cam 122 abuts against the inner wall of the lower end of the opening. During the descending process of the moving platform 1262, the shock-absorbing pad 124 and the eccentric follower block 125 together reduce the upward jump of the moving platform 1262 due to falling and colliding with the driving member 121 below it.

[0052] In one embodiment, the vibration mechanism 120 also includes a pressing component 127, which includes a pressing plate 1271 and a cylinder 1272. The pressing plate 1271 is arranged above the mold 110 to press the mold 110 on the movable platform 1262. The cylinder 1272 is arranged on the mold frame 126, and its driving end is connected to the pressing plate 1271 to drive the pressing plate 1271 to move up and down. Specifically, the cylinder 1272 is fixedly disposed above the mold 110, and the distal end of the push rod of the cylinder 1272 is fixedly connected to the pressing plate 1271. The push rod of the cylinder 1272 extends downward, and the pressing plate 1271 of the cylinder 1272 moves toward the mold 110 until the mold 110 is pressed against the movable platform 1262. The push rod of the cylinder 1272 retracts upward, and the pressing plate 1271 moves upward, allowing the mold 110 to be removed from the movable platform 1262. When the driving member 121 drives the cam 122 to rotate, the pressing assembly 127 moves up and down together with the movable platform 1262 and the mold 110.

[0053] In one embodiment, the powder feeding mechanism 130 includes a powder supply tank 131, a first weighing hopper 133, a second weighing hopper 136 and a controller; the outlet at the lower end of the powder supply tank 131 is provided with a first switch valve 132 to control the opening and closing of the outlet of the powder supply tank 131; the first weighing hopper 133 is provided below the powder supply tank 131, and the inlet at the upper end of the first weighing hopper 133 is connected to the outlet at the lower end of the powder supply tank 131, and the first weighing sensor 134 is provided on the first weighing hopper 133, 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, and the outlet at the lower end of the second weighing hopper 136 is located above the screen 112 to supply the powder to the screen 11 2 powder feeding, a second on-off valve 138 is provided at the outlet of the lower end of the second weighing hopper 136 to control the opening and closing of the outlet of the second weighing hopper 136. A second load cell 137 is provided on the second weighing hopper 136 and is electrically connected to the second weighing hopper 136. The input and output of the controller are electrically connected to the first load cell 134 and the first on-off valve 132, respectively. The input and output of the controller are also electrically connected to the second load cell 137 and the second on-off valve 138, respectively. The controller controls the opening and closing of the first on-off valve 132 based on the information output by the first load cell 134, and controls the opening and closing of the second on-off valve 138 based on the information output by the second load cell 137. The first on-off valve 132 and the second on-off valve 138 can be pneumatic valves, solenoid valves, or other valves, without particular limitation.

[0054] In detail, a powder filling port is provided at the upper end of the powder supply tank 131, and a knocking cylinder 139 is connected to the outer wall of the powder supply tank 131. The knocking cylinder 139 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. A vibration platform 135 is provided at the outlet of the lower end of the first weighing hopper 133, and the magnetic powder in the first weighing hopper 133 is vibrated into the second weighing hopper 136 through the vibration platform 135. During the operation, the operator injects magnetic powder into the powder supply tank 131 from the powder injection port, opens the first switch valve 132, and the magnetic powder flows into the first weighing hopper 133 from the outlet at the lower end of the powder supply tank 131. When the first weighing sensor 134 measures that the amount of magnetic powder in the first weighing hopper 133 reaches the first estimated weight, the controller controls the first switch valve 132 to close and controls the vibration platform 135 to start, so as to shake the magnetic powder in the first weighing hopper 133 into the second weighing hopper 136; when the second weighing sensor 13 When the measured weight of the magnetic powder in the second weighing hopper 136 reaches the second estimated weight, the controller controls the vibration platform 135 to close, and the magnetic powder in the first weighing hopper 133 stops falling into the second weighing hopper 136. Then, the controller controls the second switch valve 138 to open, and the second weighing hopper 136 spreads the powder into the screen 112. When the second weighing sensor 137 measures that the amount of powder spread by the second weighing hopper 136 into the screen 112 reaches the third estimated weight, the controller controls the second switch valve 138 to close.

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

[0056] The multiple mold cavities 1111 of the mold body 111 are arranged in sequence along the first horizontal direction. In order to improve the powder distribution uniformity of the powder feeding 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 evenly feed powder to each area of ​​the screen 112 by moving back and forth in the first horizontal direction, thereby improving the powder distribution uniformity of the screen 112 to the multiple mold cavities 1111.

[0057] The present application also proposes a powder distribution method based on the powder distribution device 100 described above, comprising 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 into the screen 112 by the powder feeding mechanism 130 is not less than the expected amount of magnetic powder to be filled in the mold body 111. This improves the uniformity of powder distribution as much as possible. In particular, for a mold body 111 with multiple mold cavities 1111, the difference in powder distribution quality between each mold cavity 1111 can be reduced.

[0059] The vibration mechanism 120 is started, and the vibration mechanism 120 drives the mold body 111 and the screen 112 to vibrate together, so that the screen 112 shakes 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 of the mold body 1111 is scraped or flattened to eliminate the unevenness of the upper surface of the magnetic powder in the mold cavity 1111 of the mold body 111 due to the difference in loose density of the pre-loaded magnetic powder, the difference in 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 scraping rake, or the surface of the magnetic powder can be flattened by matching a mesh screen of appropriate size.

[0061] The technical solution of the present application uses a vibration mechanism 120 to evenly shake the magnetic powder on the mesh surface of the screen 112 into the mold body 111 and fill it to a preset density, thereby improving the powder distribution uniformity of a single mold cavity or multiple mold cavities during the thin-film magnet forming process, thereby improving the performance and consistency of the finished product.

[0062] In the embodiment of the present application, the magnetic powder is neodymium iron boron magnetic powder, and the powder particle size is 1~10um, specifically 1um, 4um, 8um, 10um or any value therebetween, and the particle size distribution D90 / D10≤7.

[0063] In an embodiment of the present application, the magnetic powder is also mixed with an auxiliary agent, which 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, etc., which are mixers used in the industry.

[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 Testing

[0066] The powder distribution method of the present application is used to prepare NdFeB magnets, specifically as follows:

[0067] Example 1-3: Square magnets with a width * height * thickness of 40 mm * 20 mm * 9.5 mm were prepared. 25 magnets were produced based on the 25 mold cavities of the mold body. The mass distribution of these 25 magnets is shown in Table 1 below (range = maximum value - minimum value, fluctuation = range / mean / 2):

[0068]

[0069] It can be seen from Table 1 above that the differences between the maximum mass and the minimum mass of the magnets in Examples 1-3 are 1.39 g, 1.33 g, and 1.05 g, respectively, and the mass fluctuations are ±1.7%, ±2.2%, and ±1.5%, respectively; that is, in the same batch of molded magnets, the mass fluctuations of the magnets produced in different mold cavities are small, and the mass distribution uniformity of the magnetic powder in each mold cavity is very high.

[0070] Example 3-6: Preparation of hollow ring magnets. According to the 16 mold cavities of the mold body, 16 magnets can be produced. The mass distribution of these 16 magnets is shown in Table 2 below (range = maximum value - minimum value, fluctuation = range / mean value / 2):

[0071] As shown in Table 2, the differences between the maximum and minimum masses of the magnets in Examples 4-6 were 0.055g, 0.049g, and 0.049g, respectively, and the mass fluctuations were ±3.2%, ±2.9%, and ±2.8%, respectively. This indicates that within the same batch of magnets, the mass distribution of the magnetic powder within each mold cavity was highly uniform. Compared to Examples 1-3, the mass fluctuations of the ring magnets produced in Examples 4-6 were slightly greater. This is primarily due to the difficulty in filling the thin-walled ring magnets with magnetic powder, resulting in greater mass fluctuations.

[0072] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A powder distribution device for preparing thin-sheet magnets, It is characterized in that include: The mold comprises a mold body and a screen, wherein the screen is arranged above the mold and connected to the mold body, and the magnetic powder is shaken off into the mold cavity of the mold body through the screen; A powder feeding mechanism, used for feeding the magnetic powder into the screen; The vibration mechanism is connected to the mold body and is used to drive the mold body to drive the screen to vibrate together.

2. The powder distributing device according to claim 1, It is characterized in that The vibration mechanism includes 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, thereby causing the mold to vibrate.

3. The powder distributing device according to claim 2, It is characterized in that The vibration mechanism also includes a mold frame, which includes a base, a movable platform and a plurality of guide pillars arranged at intervals. The movable platform is arranged above the base, and the mold is arranged on the movable platform. The lower ends of the guide pillars are connected to the base, and the upper ends are passed through the movable platform and extend in a vertical direction. The guide pillars are slidably connected to the movable platform, and the driving member is arranged on the base. The cam is transmission-connected to the mold through the movable platform.

4. The powder distributing device according to claim 3, It is characterized in that The vibration mechanism also includes a transmission block, which is arranged above the cam. The upper end of the transmission block is connected to the moving platform, and the lower end of the transmission block abuts against the circumferential surface of the cam. The rotation of the cam drives the transmission block to move up and down with the mold.

5. The powder distributing device according to claim 4, It is characterized in that A shock-absorbing pad is provided between the moving platform and the driving member, wherein the upper end of the shock-absorbing pad is connected to the moving platform and the lower end is connected to the driving member; and / or, An eccentric follower block is arranged below the moving platform, the cam is transmission-connected with the eccentric follower block, and the eccentric follower block is connected with the moving platform.

6. The powder distributing device according to claim 3, It is characterized in that The vibration mechanism also includes a pressing component, which includes a pressing plate and a cylinder. The pressing plate is arranged above the mold to press the mold onto the movable table. The cylinder is arranged on the mold frame, and its driving end is connected to the pressing plate to drive the pressing plate to move up and down.

7. The powder distribution device according to any one of claims 1 to 6, It is characterized in that The vibration frequency of the vibration mechanism is 1-100 Hz; and / or, The mesh of the sieve is rectangular, 4-20 mm long and 1-7 mm wide; and / or, The mold body is provided with a plurality of mold cavities, and the shapes of the mold cavities include rectangular parallelepiped, cube, cylinder, torus or other irregular shapes.

8. The powder distribution device according to any one of claims 1 to 6, It is characterized in that The powder feeding mechanism comprises: A powder supply tank, the outlet of which is provided with a first switch valve at the lower end to control the opening and closing of the outlet of the powder supply tank; The first weighing hopper is arranged below the powder supply tank. The inlet at its upper end is docked with the outlet at the lower end of the powder supply tank. A first weighing sensor is arranged on the first weighing hopper, and the first weighing sensor is electrically connected to the first weighing hopper; The second weighing hopper, the inlet at its upper end is docked with the outlet at the lower end of the first weighing hopper, and the outlet at its lower end is located above the sieve to feed powder to the sieve. A second switching valve is arranged at the outlet at the lower end of the second weighing hopper to control the opening and closing of the outlet of the second weighing hopper. A second weighing sensor is arranged on the second weighing hopper, and the second weighing sensor is electrically connected to the second weighing hopper; The controller, its input end and output end are respectively electrically connected to the first weighing sensor and the first switching valve, and further, its input end and output end are respectively electrically connected to the second weighing sensor and the second switching valve. The controller controls the opening and closing of the first switching valve through the information output by the first weighing sensor, and controls the opening and closing of the second switching valve through the information output by the second weighing sensor.

9. The powder spreading device according to claim 8, characterized in that, The mold body is provided with a plurality of mold cavities, and the plurality of mold cavities are arranged in sequence along the first horizontal direction. The second weighing hopper can move back and forth along the first horizontal direction; and / or, A disperser is arranged at the outlet of the second weighing hopper to disperse the magnetic powder and then transport it into the sieve.

10. A powder spreading method based on the powder spreading device according to any one of claims 1-9, characterized in that, comprises the following steps: The powder feeding mechanism pours a sufficient amount of magnetic powder into the sieve; Start the vibration mechanism, and the vibration mechanism drives the mold body and the sieve to vibrate together, so that the sieve shakes the magnetic powder into the mold cavities of the mold body until the density of the magnetic powder in the mold cavities of the mold cavity body reaches a preset density value; Level or flatten the surface of the magnetic powder in the mold cavities of the mold cavity body.

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