NdFeB permanent magnet magnetic domain stability regulation and control device and preparation method thereof

Abstract

The invention discloses a neodymium-iron-boron permanent magnet magnetic domain stability regulation and control device and a preparation method thereof, and belongs to the technical field of permanent magnet preparation, and the neodymium-iron-boron permanent magnet magnetic domain stability regulation and control device comprises a rack, a pressing box body fixed at the top of the rack, and an operation opening formed in the front end of the pressing box body. The liquid cooling mechanism composed of the sealing water bin, the liquid inlet pipe, the backflow water bin, the backflow pipe, the cylinder body, the piston and the rack is arranged on the rack, the rack is meshed with the first gear, in the pressing forming process, the sealing water bin can be inflated, the interior of the sealing water bin is in a high-pressure state, and in the pressing and pressure maintaining process, the sealing water bin is inflated to be in a high-pressure state. Cooling liquid in the sealed water sump continuously enters the spiral water pipe under the extrusion of pressure for water cooling, so that the temperature of an electromagnet coil is ensured, the electromagnetic intensity is ensured, the magnetic domain is stably regulated and controlled, and the process is actively carried out by adopting a mechanical linkage control mode in the pressing process; the control and the use are more convenient, and the practicability is higher.

Description

Technical Field

[0001] The present invention relates to a magnetic domain stabilization control device, in particular to a magnetic domain stabilization control device for a neodymium iron boron permanent magnet. The present invention also relates to a preparation method, in particular to a method for preparing a neodymium iron boron permanent magnet, and belongs to the technical field of permanent magnet preparation. Background Art

[0002] During the preparation of NdFeB permanent magnets, such as the magnetic field orientation pressing stage of the powder metallurgy process, strong magnetic field application equipment is used to orient the magnetic powder in a specific direction during pressing, which helps to form a stable magnetic domain structure. Common devices that generate strong magnetic fields include electromagnets, superconducting magnets, etc.

[0003] At present, in the process of using electromagnets for magnetic domain stabilization control, in order to avoid magnetic field attenuation caused by coil temperature rise, water cooling or oil cooling channel heat dissipation is used for cooling. However, during the cooling process, a complex control system is required to circulate the liquid. The production and use costs of the equipment are high, and the position of the electromagnet protrudes from the outside of the mold base, affecting the placement of the mold and making it inconvenient to use. In addition, during the pressing process of the mold, the position of the mold cannot be corrected, which can easily lead to pressure imbalance and affect the orientation and solidification of the magnetic powder.

[0004] To this end, a NdFeB permanent magnet magnetic domain stabilization control device and its preparation method are designed to optimize the above problems. Summary of the Invention

[0005] The main purpose of the present invention is to provide a NdFeB permanent magnet magnetic domain stabilization control device and a preparation method thereof, by arranging the electromagnet coil inside the collar, and the collar is sleeved on the outside of the mold base and can slide vertically, and then used in conjunction with a lifting mechanism consisting of a mounting ring, a vertical groove, a support plate, a first spring, a screw, a fixed plate, a rotating rod, a connecting rod, a through hole, a guide block, a spiral groove, a first gear, a second gear, and a sliding rod, so that during the pressing and forming process, the collar can be automatically raised as the hydraulic cylinder extends, and after forming, the collar can be automatically controlled to move down and hidden as the hydraulic cylinder retracts, so that the mold can be placed and taken out during use, which is more convenient to use. A liquid cooling mechanism consisting of a sealed water tank, a liquid inlet pipe, a reflux water tank, a reflux pipe, a cylinder body, a piston, and a rack is arranged on the frame, and the rack is meshed with the first gear, so that during the pressing and forming process , the inside of the sealed water tank is inflated to put it in a high-pressure state. During the pressing and holding process, the coolant inside the sealed water tank continuously enters the inside of the spiral water pipe under the pressure squeeze to perform water cooling, ensuring the temperature of the electromagnet coil, ensuring the electromagnetic strength, and stably regulating the magnetic domain. The process is actively carried out by mechanical linkage control during the pressing process, which makes control and use more convenient and more practical. A correction mechanism is formed by arranging a groove, a push rod, a push block, a second spring on the top of the mold base and cooperating with the guide groove on the inside of the collar to form a correction mechanism. During the rising process of the collar, multiple groups of push rods can be automatically controlled to move toward the mold position, and the mold can be squeezed and corrected to ensure that the cavity is located at the center of the electromagnet pole head, so that the magnetic field evenly covers the magnetic powder filling area, and ensures pressure balance during the pressing process, ensuring that the magnetic powder completes orientation solidification under uniform pressure.

[0006] The purpose of the present invention can be achieved by adopting the following technical solutions:

[0007] A device for regulating and controlling magnetic domain stability of a neodymium iron boron permanent magnet comprises a frame, a pressing box fixed on the top of the frame, an operating port provided at the front end of the pressing box, a support platform horizontally arranged inside the pressing box and located below the operating port, a hydraulic cylinder vertically installed on the top of the pressing box, and a pressing block installed at the output end of the hydraulic cylinder; a mold base is fixed at the middle position of the bottom of the pressing box, a collar is provided on the outside of the mold base, an electromagnet coil is provided inside the collar, a spiral water pipe is provided on the outside of the electromagnet coil, a liquid cooling mechanism connected to the spiral water pipe is provided at the bottom of the frame, a lifting mechanism for controlling the vertical lifting of the collar is provided on one side of the inside of the pressing box, and a correction mechanism for correcting the mold position is provided on the top of the mold base.

[0008] Preferably, an ultrasonic vibrator is provided on the outside of the pressing box, and a vibration rod is vertically installed inside the mold base.

[0009] Preferably: the lifting mechanism includes a mounting ring, a vertical slot, a support plate, a first spring, a screw, a fixed plate and a rotating assembly, the mounting ring is fixed to the bottom end of the sleeve, a vertical slot is opened on one side of the mounting ring, a support plate is vertically slidably arranged inside the vertical slot, a first spring is provided between the top of the support plate and the inner top of the mounting ring, a screw is vertically rotated and installed on the top of the frame, the screw is threadedly connected to the support plate, a fixed plate is fixed to the inner side of the pressing box, the top of the screw is rotatably connected to the fixed plate, and a rotating assembly is provided at the bottom end of the screw.

[0010] Preferably: the rotating assembly includes a rotating rod, a connecting rod, a through hole, a guide block, a spiral groove, a first gear and a second gear. The rotating rod is rotatably installed on the top of the frame. The output end of the hydraulic cylinder is horizontally fixed with a connecting rod. A through hole is provided on the connecting rod. The rotating rod passes through the inside of the through hole. A spiral groove is provided on the outside of the rotating rod. A guide block is fixed on the inside of the through hole. The guide block slides inside the spiral groove. The bottom end of the spiral groove is fixed with the first gear. The bottom end of the screw is fixed with the second gear meshing with the first gear.

[0011] Preferably, the supporting plate is vertically slidably connected to the bottom end of the rotating rod, the rotating rod is rotationally connected to the fixed plate, a sliding rod is vertically fixed to the top of the fixed plate, and the sliding rod is vertically slidably connected to the connecting rod.

[0012] Preferably: the liquid cooling mechanism includes a sealed water tank, a liquid inlet pipe, a reflux water tank, a reflux pipe and an air filling and exhaust assembly. The sealed water tank is fixed inside the frame, and the inside of the sealed water tank is in a sealed state. The inside of the sealed water tank is provided with a liquid inlet pipe connected to one end of the spiral water pipe. A reflux water tank is provided on the side of the sealed water tank. The top of the reflux water tank is open. A reflux pipe is provided between the reflux water tank and the other end of the spiral water pipe. An air filling and exhaust assembly is provided on the side of the sealed water tank.

[0013] Preferably: the inflation and exhaust assembly includes a cylinder, a piston and a rack. The cylinder is fixed to the side of the sealed water tank and is connected to the sealed water tank. A piston is slidingly provided inside the cylinder, and a rack meshing with the first gear is provided on the side of the piston.

[0014] Preferably, the sides of the sealed water tank and the return pipe are both provided with heat sinks, and the heat sinks both extend into the interior of the coolant.

[0015] Preferably: the correction mechanism includes a groove, a push rod, a push block, a second spring and a guide groove, the groove is opened at the top of the mold base, the side of the groove is evenly slidably provided with a push rod, the end of the push rod located inside the groove is fixed with a push block, a second spring is provided between the push block and the inner side of the groove, the inner side of the ring is opened with a guide groove that cooperates with the push rod, the push rod is inserted into the inside of the guide groove, and the bottom of the guide groove is an inclined surface.

[0016] The present invention also provides a method for preparing a NdFeB permanent magnet, comprising the following steps:

[0017] Step 1: Inert gas is injected into the pressing box to prevent oxidation of the raw materials, and then NdFeB magnetic powder is filled into the mold cavity, and then the mold is placed in the groove on the top of the mold base;

[0018] Step 2: Start the hydraulic cylinder to drive the pressure block to move downward. The guide block will slide inside the spiral groove, thereby controlling the rotation of the rotating rod. The rotation of the rotating rod cooperates with the first gear and the second gear to control the rotation of the screw. The rotation of the screw drives the support plate and the mounting ring to move upward, thereby moving the collar and the electromagnet coil upward to cover the mold.

[0019] Step 3: As the collar moves upward, the bottom of the guide groove squeezes the end of the push rod, controlling the push block to move toward the mold, and correcting the mold to ensure that the cavity is located at the center of the electromagnet pole head, so that the magnetic field evenly covers the magnetic powder filling area.

[0020] Step 4: When the mounting ring moves up until it fits against the bottom of the fixed plate, the pressing block fits against the top of the mold. During pressing, the pressing block will move down again to squeeze the mold, and the screw will rotate and control the support plate to move up. At this time, the support plate will squeeze the first spring, but the position of the mounting ring is fixed at this time, and the position of the collar will not change, so as to ensure the stability of the magnetic field position;

[0021] Step 5: When the hydraulic cylinder starts to control the downward movement of the pressing block, the rotation of the first gear will drive the horizontal movement of the rack, moving the piston toward the sealed water tank. At this time, the pressure inside the sealed water tank increases, and the coolant will continue to enter the spiral water pipe through the liquid inlet pipe. It takes a certain amount of time for the liquid inside the sealed water tank to be discharged. This time is longer than the holding time of the mold during pressing. Therefore, during the pressing process, the coolant will continue to cool the electromagnet to ensure the stability of the magnetic field, and the water discharged from the spiral water pipe will enter the reflux water tank.

[0022] Step 6: After the pressing and forming, the hydraulic cylinder controls the pressing block to move up and reset. At this time, the rotating rod rotates in the opposite direction to control the mounting ring to reset until the top of the collar and the top of the mold base are at the same level. After the collar is reset, the second spring controls the push block to reset, and the push rod is inserted into the guide groove again. When the piston is reset, the coolant inside the reflux tank is returned to the inside of the sealed water tank through the reflux pipe for recycling.

[0023] The beneficial effects of the present invention are:

[0024] The present invention provides a NdFeB permanent magnet magnetic domain stabilization control device and a preparation method thereof. The device comprises an electromagnet coil disposed inside a collar, which is sleeved on the outside of a mold base and can slide vertically. The collar is then used in conjunction with a lifting mechanism consisting of a mounting ring, a vertical groove, a support plate, a first spring, a screw, a fixing plate, a rotating rod, a connecting rod, a through hole, a guide block, a spiral groove, a first gear, a second gear, and a sliding rod. During the pressing and forming process, the collar is automatically raised as the hydraulic cylinder extends. After forming, the collar is automatically controlled to move downward and hide as the hydraulic cylinder retracts. This allows the mold to be placed and removed during use, making it more convenient to use.

[0025] By arranging a liquid cooling mechanism consisting of a sealed water tank, a liquid inlet pipe, a reflux water tank, a reflux pipe, a cylinder body, a piston, and a rack on the frame, and the rack is meshed with the first gear, the sealed water tank can be inflated during the pressing process to put the interior of the sealed water tank in a high-pressure state. During the pressing and pressure-maintaining process, the coolant inside the sealed water tank continuously enters the interior of the spiral water pipe under the pressure squeeze to perform water cooling, thereby ensuring the temperature of the electromagnet coil, ensuring the electromagnetic strength, and stably regulating the magnetic domain. Moreover, the process is actively carried out by a mechanical linkage control method during the pressing process, which makes control and use more convenient and more practical.

[0026] By arranging a groove, a push rod, a push block, a second spring on the top of the mold base and then cooperating with the guide groove on the inner side of the ring to form a correction mechanism, it can automatically control multiple groups of push rods to move toward the mold position during the rising process of the ring, and perform extrusion correction on the mold to ensure that the cavity is located at the center of the electromagnet pole head, so that the magnetic field evenly covers the magnetic powder filling area, and ensures pressure balance during the pressing process, ensuring that the magnetic powder completes orientation solidification under uniform pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a front cross-sectional view of a preferred embodiment of a NdFeB permanent magnet magnetic domain stabilization control device and a preparation method thereof according to the present invention;

[0028] Figure 2 This is a structural diagram of the outer side of a mold base in a preferred embodiment of a NdFeB permanent magnet magnetic domain stabilization control device and a preparation method thereof according to the present invention;

[0029] Figure 3 This is a preferred embodiment of a NdFeB permanent magnet magnetic domain stabilization control device and a preparation method thereof of the present invention. Figure 2 Enlarged view of point A in the middle;

[0030] Figure 4 This is a diagram of a lifting mechanism of a preferred embodiment of a NdFeB permanent magnet magnetic domain stabilization control device and a preparation method thereof according to the present invention;

[0031] Figure 5 This is a preferred embodiment of a NdFeB permanent magnet magnetic domain stabilization control device and a preparation method thereof of the present invention. Figure 4 Enlarged view of point B in the middle;

[0032] Figure 6 This is a preferred embodiment of a NdFeB permanent magnet magnetic domain stabilization control device and a preparation method thereof of the present invention. Figure 4 Enlarged view of point C in the middle;

[0033] Figure 7 A diagram of a liquid cooling mechanism in a preferred embodiment of a NdFeB permanent magnet magnetic domain stabilization control device and a preparation method thereof according to the present invention;

[0034] Figure 8 This is a front view of a preferred embodiment of a NdFeB permanent magnet magnetic domain stabilization control device and a preparation method thereof according to the present invention.

[0035] In the figure: 1, frame; 101, pressing box; 102, operation port; 103, support platform; 104, hydraulic cylinder; 105, pressing block

[0036] 2. Mold base; 3. Ring; 4. Electromagnet coil; 5. Spiral water pipe;

[0037] 6. Liquid cooling mechanism; 601. Sealed water tank; 602. Liquid inlet pipe; 603. Return water tank; 604. Return pipe; 605. Cylinder; 606. Piston; 607. Rack;

[0038] 7. Lifting mechanism; 701. Mounting ring; 702. Vertical slot; 703. Support plate; 704. First spring; 705. Screw; 706. Fixing plate; 707. Rotating rod; 708. Connecting rod; 709. Through hole; 710. Guide block; 711. Spiral groove; 712. First gear; 713. Second gear; 714. Sliding rod;

[0039] 8. Correction mechanism; 801. Groove; 802. Push rod; 803. Push block; 804. Second spring; 805. Guide groove;

[0040] 9. Vibrating rod; 10. Ultrasonic vibrator. DETAILED DESCRIPTION

[0041] In order to make the technical solution of the present invention more clear and specific to those skilled in the art, the present invention is described in further detail below with reference to embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0042] like Figures 1-8As shown, this embodiment provides a device for regulating and controlling magnetic domain stabilization of NdFeB permanent magnets, comprising a frame 1, a pressing box 101 fixed on the top of the frame 1, an operating port 102 opened at the front end of the pressing box 101, a support 103 horizontally arranged inside the pressing box 101 and located below the operating port 102, a hydraulic cylinder 104 vertically installed on the top of the pressing box 101, and a pressing block 105 installed at the output end of the hydraulic cylinder 104. A mold base 2 is fixed at the middle position of the bottom of the pressing box 101, a collar 3 is provided on the outer side of the mold base 2, an electromagnet coil 4 is provided inside the collar 3, a spiral water pipe 5 is provided on the outer side of the electromagnet coil 4, a liquid cooling mechanism 6 connected to the spiral water pipe 5 is provided at the bottom of the frame 1, a lifting mechanism 7 for controlling the vertical lifting of the collar 3 is provided on one side of the pressing box 101, and a correction mechanism 8 for correcting the mold position is provided on the top of the mold base 2.

[0043] The overall working principle is: inert gas is flushed into the inside of the pressing box 101 to avoid oxidation of the raw materials. The operator inserts his hand into the inside of the pressing box 101 from the inside of the operating port 102, and then fills the inside of the mold cavity with neodymium iron boron magnetic powder, and then places the mold on the top of the mold base 2. After the mold is placed, the hydraulic cylinder 104 controls the downward movement of the pressing block 105, and while the hydraulic cylinder 104 is extended, the lifting mechanism 7 controls the upward movement of the ring 3 to cover the mold, and in the process of the ring 3 rising, the correction mechanism 8 corrects the position of the mold to ensure that the cavity is located at the center of the electromagnet pole head, so that the magnetic field evenly covers the magnetic powder filling area. When the pressing block 105 contacts the mold, the position of the ring 3 is fixed, the power of the electromagnet coil 4 is turned on, a stable magnetic field is generated, and the liquid cooling mechanism 6 is used to cool the electromagnet coil 4 to ensure the stability of the magnetic field, so as to improve the stability of the magnetic domain regulation.

[0044] In this embodiment, an ultrasonic vibrator 10 is provided on the outside of the pressing box 101 , and a vibration rod 9 is vertically installed inside the mold base 2 .

[0045] Partial working principle: The ultrasonic vibrator 10 operates at a frequency of 20-40kHz and an amplitude of 5-10μm, which promotes more flexible rotation of magnetic powder in the magnetic field, reduces agglomeration or stagnation, and improves orientation efficiency. The vibration direction must be strictly consistent with the direction of the magnetic field to avoid shear force that destroys the orientation.

[0046] In this embodiment, the lifting mechanism 7 includes a mounting ring 701, a vertical slot 702, a support plate 703, a first spring 704, a screw 705, a fixed plate 706 and a rotating assembly. The mounting ring 701 is fixed to the bottom end of the sleeve 3. A vertical slot 702 is provided on one side of the mounting ring 701. A support plate 703 is vertically slidably provided inside the vertical slot 702. A first spring 704 is provided between the top of the support plate 703 and the inner top of the mounting ring 701. A screw 705 is vertically rotatably installed on the top of the frame 1. The screw 705 is threadedly connected to the support plate 703. A fixed plate 706 is fixed to the inner side of the pressing box 101. The top of the screw 705 is rotatably connected to the fixed plate 706, and a rotating assembly is provided at the bottom end of the screw 705.

[0047] Local working principle: While the pressure block 105 moves downward, the rotating assembly will drive the screw 705 to rotate. The rotation of the screw 705 drives the support plate 703 and the mounting ring 701 to move upward until the top of the support plate 703 is in contact with the bottom of the fixed plate 706. At this time, the position of the support plate 703 is fixed. Even if the rotating assembly controls the screw 705 to rotate again, it will only control the upward movement of the support plate 703 and squeeze the first spring 704.

[0048] In this embodiment, the rotating assembly includes a rotating rod 707, a connecting rod 708, a through hole 709, a guide block 710, a spiral groove 711, a first gear 712 and a second gear 713. The rotating rod 707 is rotatably installed on the top of the frame 1. The connecting rod 708 is horizontally fixed to the output end of the hydraulic cylinder 104. The connecting rod 708 is provided with a through hole 709. The rotating rod 707 passes through the inside of the through hole 709. A spiral groove 711 is provided on the outside of the rotating rod 707. A guide block 710 is fixed on the inside of the through hole 709. The guide block 710 slides inside the spiral groove 711. The bottom end of the spiral groove 711 is fixed with a first gear 712, and the bottom end of the screw 705 is fixed with a second gear 713 that meshes with the first gear 712.

[0049] Local working principle: When the hydraulic cylinder 104 drives the pressure block 105 to move downward, the guide block 710 will slide inside the spiral groove 711, thereby controlling the rotation of the rotating rod 707. The rotation of the rotating rod 707 cooperates with the first gear 712 and the second gear 713 to control the rotation of the screw 705. The helix angle of the spiral groove 711 is 30°-45°, and the lead is 20-30mm, ensuring that the lifting stroke of the support plate 703 is 10-15mm when the rotating rod 707 rotates one circle, meeting the requirements of slow and smooth lifting of the ring 3.

[0050] In this embodiment, the support plate 703 is vertically slidably connected to the bottom end of the rotating rod 707, the rotating rod 707 is rotationally connected to the fixed plate 706, and a sliding rod 714 is vertically fixed to the top of the fixed plate 706, and the sliding rod 714 is vertically slidably connected to the connecting rod 708.

[0051] Partial working principle: When the support plate 703 moves upward, the rotating rod 707 can limit the support plate 703. The existence of the fixed plate 706 will not affect the rotation of the rotating rod 707. The use of the sliding rod 714 can ensure the stable vertical sliding of the connecting rod 708.

[0052] In this embodiment, the liquid cooling mechanism 6 includes a sealed water tank 601, a liquid inlet pipe 602, a reflux water tank 603, a reflux pipe 604 and an air filling and exhaust assembly. The sealed water tank 601 is fixed inside the frame 1, and the inside of the sealed water tank 601 is in a sealed state. The inside of the sealed water tank 601 is provided with a liquid inlet pipe 602 connected to one end of the spiral water pipe 5. The side of the sealed water tank 601 is provided with a reflux water tank 603. The top of the reflux water tank 603 is open. A reflux pipe 604 is provided between the reflux water tank 603 and the other end of the spiral water pipe 5. The side of the sealed water tank 601 is provided with an air filling and exhaust assembly.

[0053] Local working principle: The material of the sealed water tank 601 and the return water tank 603 are both 304 stainless steel, and the inner wall is coated with polytetrafluoroethylene coating to prevent corrosion by the coolant. The coolant is deionized water, and the initial temperature is controlled at 20±2°C. The flow is adjusted by the throttle valve on the liquid inlet pipe 602 to ensure that the flow rate in the spiral water pipe 5 is 0.5-1m / s. Before pressing, the inflation and exhaust components will inject gas into the interior of the sealed water tank 601, and the interior of the sealed water tank 601 is in a high-pressure state. The cooling water inside the sealed water tank 601 will enter the interior of the spiral water pipe 5 through the liquid inlet pipe 602. The sealed water tank 601 has a large air pressure, and it takes a certain amount of time for the water to be discharged. Therefore, during the pressing process, the cooling water will always enter the interior of the spiral water pipe 5 through the liquid inlet pipe 602, and then flow into the interior of the return water tank 603 from the return pipe 604 to cool the electromagnet.

[0054] In this embodiment, the inflation and exhaust assembly includes a cylinder body 605, a piston 606 and a rack 607. The cylinder body 605 is fixed to the side of the sealed water tank 601 and is connected to the sealed water tank 601. A piston 606 is slidingly provided inside the cylinder body 605, and a rack 607 is provided on the side of the piston 606, which is engaged with the first gear 712.

[0055] Local working principle: During the downward movement of the pressure block 105, the rotation of the first gear 712 will drive the horizontal movement of the rack 607, moving the piston 606 toward the sealed water tank 601. At this time, the pressure inside the sealed water tank 601 increases. When the pressing is completed, the piston 606 is reset, and the coolant inside the reflux water tank 603 is returned to the inside of the sealed water tank 601 through the reflux pipe 604 for recycling. The piston 606 has a diameter of 50mm and a stroke of 30mm. The rack 607 has 20 teeth and the first gear 712 has a module of 2, which ensures that the pressure in the sealed water tank 601 is stably increased to 0.5MPa when the piston 606 moves.

[0056] In this embodiment, heat sinks are provided on the sides of the sealed water tank 601 and the return pipe 604 , and the heat sinks extend into the interior of the coolant.

[0057] Partial working principle: The use of heat sinks can speed up the cooling of the coolant and ensure the use effect.

[0058] In this embodiment, the correction mechanism 8 includes a groove 801, a push rod 802, a push block 803, a second spring 804 and a guide groove 805. The groove 801 is opened at the top of the mold base 2, and the push rod 802 is evenly slidably set on the side of the groove 801. The push block 803 is fixed at one end of the push rod 802 located inside the groove 801. A second spring 804 is provided between the push block 803 and the inner side of the groove 801. A guide groove 805 cooperating with the push rod 802 is opened on the inner side of the ring 3. The push rod 802 is inserted into the inside of the guide groove 805, and the bottom of the guide groove 805 is an inclined surface.

[0059] Local working principle: During the upward movement of the collar 3, the bottom of the guide groove 805 squeezes the end of the push rod 802, controls the push block 803 to move toward the mold, and performs extrusion correction on the mold to ensure that the cavity is located at the center of the electromagnet pole head, so that the magnetic field evenly covers the magnetic powder filling area. When the collar 3 moves down and resets, the second spring 804 controls the push block 803 to reset, and the push rod 802 is inserted into the inside of the guide groove 805 again. The angle between the inclined surface at the bottom of the guide groove 805 and the horizontal plane is 45°, and the height difference is 5mm, ensuring that when the collar 3 rises, the horizontal movement of the push rod 802 is 5mm, thereby achieving precise correction of the mold.

[0060] like Figures 1-8 As shown, this embodiment provides a method for preparing a NdFeB permanent magnet as follows:

[0061] Step 1: Inert gas is injected into the pressing box 101 to prevent oxidation of the raw materials. The inert gas is high-purity argon (purity ≥ 99.99%), and the inflation pressure is 105kPa (5kPa higher than atmospheric pressure). Ensure that the oxygen content inside the pressing box is less than 10ppm. Then, NdFeB magnetic powder is filled into the mold cavity, and the mold is placed in the groove 801 on the top of the mold base 2;

[0062] Step 2: Start the hydraulic cylinder 104 to drive the pressing block 105 to move downward, and the guide block 710 will slide inside the spiral groove 711, thereby controlling the rotation of the rotating rod 707. The rotation of the rotating rod 707 cooperates with the first gear 712 and the second gear 713 to control the rotation of the screw 705. The rotation of the screw 705 drives the support plate 703 and the mounting ring 701 to move upward, thereby moving the collar 3 and the electromagnet coil 4 upward to cover the mold;

[0063] Step 3: As the collar 3 moves upward, the bottom of the guide groove 805 squeezes the end of the push rod 802, controlling the push block 803 to move toward the mold, correcting the mold, and ensuring that the cavity is located at the center of the electromagnet pole head so that the magnetic field evenly covers the magnetic powder filling area. The downward speed of the hydraulic cylinder 104 is controlled at 5 mm / s, and the rising speed of the collar 3 is synchronized with the downward speed of the pressing block 105.

[0064] Step 4: When the mounting ring 701 moves up until it fits against the bottom of the fixing plate 706, the pressing block 105 fits against the top of the mold. During pressing, the pressing block 105 will move down again to squeeze the mold, and the screw 705 will rotate and control the support plate 703 to move up. At this time, the support plate 703 will squeeze the first spring 704, but the position of the mounting ring 701 is fixed at this time, and the position of the collar 3 will not change, so as to ensure the stability of the magnetic field position;

[0065] Step 5: When the hydraulic cylinder 104 starts to control the pressure block 105 to move downward, the rotation of the first gear 712 will drive the horizontal movement of the rack 607, and move the piston 606 toward the sealed water tank 601. At this time, the pressure inside the sealed water tank 601 increases, and the coolant will continue to enter the spiral water pipe 5 through the liquid inlet pipe 602. It takes a certain amount of time for the liquid inside the sealed water tank 601 to be discharged. This time is greater than the holding time of the mold during pressing. Therefore, during the pressing process, the coolant will continue to cool the electromagnet to ensure the stability of the magnetic field. The water discharged from the spiral water pipe 5 enters the reflux water tank 603. The holding time is 30-60s. The current of the electromagnet coil is set to 50-100A according to the coercive force of the magnetic powder to ensure that the magnetic field strength is ≥1.5T. The coolant circulation time covers the holding time. The capacity of the sealed water tank 601 is designed to be 5L to meet the continuous liquid supply demand.

[0066] Step 6: After the pressing and forming, the hydraulic cylinder 104 controls the pressing block 105 to move up and reset. At this time, the rotating rod 707 rotates in the opposite direction to control the mounting ring 701 to reset until the top of the collar 3 and the top of the mold base 2 are at the same horizontal plane. After the collar 3 is reset, the second spring 804 controls the push block 803 to reset, and the push rod 802 is inserted into the guide groove 805 again. When the piston 606 is reset, the coolant inside the reflux water tank 603 is returned to the inside of the sealed water tank 601 through the reflux pipe 604 for recycling.

[0067] The above is only a further embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes based on the technical solutions and concepts of the present invention within the scope disclosed by the present invention, which fall within the scope of protection of the present invention.

Claims

1. A device for controlling magnetic domain stability of a neodymium iron boron permanent magnet, comprising a frame (1), a pressing box (101) fixed on the top of the frame (1), an operating port (102) provided at the front end of the pressing box (101), a support (103) horizontally arranged inside the pressing box (101) and located below the operating port (102), a hydraulic cylinder (104) vertically mounted on the top of the pressing box (101), and a pressing block (105) mounted at the output end of the hydraulic cylinder (104), characterized in that: A mold base (2) is fixed at the middle position of the bottom of the pressing box (101), a sleeve (3) is provided on the outer side of the mold base (2), an electromagnet coil (4) is provided inside the sleeve (3), a spiral water pipe (5) is provided on the outer side of the electromagnet coil (4), a liquid cooling mechanism (6) connected to the spiral water pipe (5) is provided at the bottom of the frame (1), a lifting mechanism (7) for controlling the vertical lifting of the sleeve (3) is provided on one side of the inside of the pressing box (101), and a correction mechanism (8) for correcting the position of the mold is provided on the top of the mold base (2).

2. The device for controlling magnetic domain stabilization of a NdFeB permanent magnet according to claim 1, wherein: An ultrasonic vibrator (10) is provided on the outside of the pressing box (101), and a vibration rod (9) is vertically installed inside the mold base (2).

3. The device for controlling magnetic domain stabilization of a NdFeB permanent magnet according to claim 1, wherein: The lifting mechanism (7) comprises a mounting ring (701), a vertical slot (702), a supporting plate (703), a first spring (704), a screw (705), a fixed plate (706) and a rotating assembly. The mounting ring (701) is fixed to the bottom end of the collar (3). A vertical slot (702) is provided on one side of the mounting ring (701). A supporting plate (703) is vertically slidably provided inside the vertical slot (702). A first spring (704) is provided between the top of the supporting plate (703) and the inner top of the mounting ring (701). A screw (705) is vertically rotatably installed on the top of the frame (1). The screw (705) is threadedly connected to the supporting plate (703). A fixed plate (706) is fixed to the inner side of the pressing box (101). The top of the screw (705) is rotatably connected to the fixed plate (706). A rotating assembly is provided at the bottom end of the screw (705).

4. The device for controlling magnetic domain stabilization of a NdFeB permanent magnet according to claim 3, wherein: The rotating assembly comprises a rotating rod (707), a connecting rod (708), a through hole (709), a guide block (710), a spiral groove (711), a first gear (712) and a second gear (713). The rotating rod (707) is rotatably mounted on the top of the frame (1). The output end of the hydraulic cylinder (104) is horizontally fixed with a connecting rod (708). A through hole (709) is provided on the connecting rod (708). The rotating rod (707) passes through the inside of the through hole (709). A spiral groove (711) is provided on the outside of the rotating rod (707). A guide block (710) is fixed on the inside of the through hole (709). The guide block (710) slides inside the spiral groove (711). The bottom end of the spiral groove (711) is fixed with a first gear (712). The bottom end of the screw rod (705) is fixed with a second gear (713) meshing with the first gear (712).

5. The device for controlling magnetic domain stabilization of a NdFeB permanent magnet according to claim 4, characterized in that: The supporting plate (703) is vertically slidably connected to the bottom end of the rotating rod (707), the rotating rod (707) is rotatably connected to the fixed plate (706), a sliding rod (714) is vertically fixed to the top of the fixed plate (706), and the sliding rod (714) is vertically slidably connected to the connecting rod (708).

6. The device for controlling magnetic domain stabilization of a NdFeB permanent magnet according to claim 4, characterized in that: The liquid cooling mechanism (6) comprises a sealed water tank (601), a liquid inlet pipe (602), a return water tank (603), a return pipe (604) and an air filling and exhaust assembly. The sealed water tank (601) is fixed inside the frame (1), and the inside of the sealed water tank (601) is in a sealed state. The inside of the sealed water tank (601) is provided with a liquid inlet pipe (602) which is connected to one end of the spiral water pipe (5). The side of the sealed water tank (601) is provided with a return water tank (603). The top of the return water tank (603) is open. The return pipe (604) is provided between the return water tank (603) and the other end of the spiral water pipe (5). The side of the sealed water tank (601) is provided with an air filling and exhaust assembly.

7. The device for controlling magnetic domain stabilization of a NdFeB permanent magnet according to claim 6, characterized in that: The inflation and exhaust assembly comprises a cylinder body (605), a piston (606) and a rack (607). The cylinder body (605) is fixed to the side of the sealed water tank (601) and is in communication with the sealed water tank (601). The piston (606) is slidably provided inside the cylinder body (605). The side of the piston (606) is provided with a rack (607) that meshes with the first gear (712).

8. The device for controlling magnetic domain stabilization of a NdFeB permanent magnet according to claim 7, characterized in that: The sides of the sealed water tank (601) and the return pipe (604) are both provided with heat sinks, and the heat sinks are both extended into the interior of the coolant.

9. The device for controlling magnetic domain stabilization of a NdFeB permanent magnet according to any one of claims 1 to 8, characterized in that: The correction mechanism (8) comprises a groove (801), a push rod (802), a push block (803), a second spring (804) and a guide groove (805). The groove (801) is provided at the top of the mold base (2). The push rod (802) is evenly slidably provided on the side of the groove (801). A push block (803) is fixed to one end of the push rod (802) located inside the groove (801). A second spring (804) is provided between the push block (803) and the inner side of the groove (801). A guide groove (805) cooperating with the push rod (802) is provided on the inner side of the collar (3). The push rod (802) is inserted into the inner side of the guide groove (805), and the bottom of the guide groove (805) is an inclined surface.

10. A method for preparing a NdFeB permanent magnet, based on the NdFeB permanent magnet magnetic domain stabilization control device according to claim 9, characterized in that: The steps include: Step 1: Inert gas is injected into the interior of the pressing box (101) to prevent oxidation of the raw materials, and then NdFeB magnetic powder is filled into the interior of the mold cavity, and then the mold is placed in the groove (801) on the top of the mold base (2); Step 2: Start the hydraulic cylinder (104) to drive the pressing block (105) to move downward, and the guide block (710) will slide inside the spiral groove (711), thereby controlling the rotation of the rotating rod (707). The rotation of the rotating rod (707) cooperates with the first gear (712) and the second gear (713) to control the rotation of the screw (705). The rotation of the screw (705) drives the support plate (703) and the mounting ring (701) to move upward, thereby moving the collar (3) and the electromagnet coil (4) upward to cover the mold; Step 3: When the collar (3) moves upward, the bottom of the guide groove (805) squeezes the end of the push rod (802), controls the push block (803) to move toward the mold, and performs extrusion correction on the mold to ensure that the mold cavity is located at the center of the electromagnet pole head, so that the magnetic field evenly covers the magnetic powder filling area; Step 4: When the mounting ring (701) moves upward until it fits against the bottom of the fixed plate (706), the pressing block (105) fits against the top of the mold. During the pressing process, the pressing block (105) moves downward again to squeeze the mold, and the screw (705) rotates and controls the support plate (703) to move upward. At this time, the support plate (703) squeezes the first spring (704), but the position of the mounting ring (701) is fixed, and the position of the collar (3) does not change, so as to ensure the stability of the magnetic field position. Step 5: When the hydraulic cylinder (104) starts to control the pressing block (105) to move downward, the rotation of the first gear (712) drives the horizontal movement of the rack (607), and moves the piston (606) toward the sealed water tank (601). At this time, the pressure inside the sealed water tank (601) increases, and the coolant continues to enter the spiral water pipe (5) through the liquid inlet pipe (602). It takes a certain amount of time for the liquid inside the sealed water tank (601) to be discharged. This time is greater than the holding time of the mold during pressing. Therefore, during the pressing process, the coolant will continue to cool the electromagnet to ensure the stability of the magnetic field. The water discharged from the spiral water pipe (5) enters the reflux water tank (603). Step 6: After the pressing and forming, the hydraulic cylinder (104) controls the pressing block (105) to move upward and reset. At this time, the rotating rod (707) rotates in the opposite direction to control the mounting ring (701) to reset until the top of the collar (3) and the top of the mold base (2) are located at the same horizontal plane. After the collar (3) is reset, the second spring (804) controls the push block (803) to reset, and the push rod (802) is inserted into the inside of the guide groove (805) again. When the piston (606) is reset, the coolant inside the reflux water tank (603) is returned to the inside of the sealed water tank (601) through the reflux pipe (604) for recycling.

Images