CN116652182A - A sintered material box and method for improving the consistency of magnetic properties of rare earth permanent magnet materials - Google Patents

Abstract

The invention discloses a sintering material box and a method for improving the consistency of the magnetic properties of rare earth permanent magnet materials. The bottom plate is arranged in the direction of front, back, left, right, bottom and connected in sequence. The front side plate, the rear side plate, the left side plate, the right side plate and the bottom plate form a rectangular material cavity. The middle part of the upper end of the front side plate is provided with a downward depression The middle part of the upper end of the rear side plate is provided with a second groove recessed downward, the middle part of the upper end of the left side plate is provided with a third groove recessed downward, and the middle part of the upper end of the right side plate is provided with a downward recess Depressed fourth groove; the advantage is that while taking into account the airtightness and exhaust function, while improving the consistency of the remanence and intrinsic coercive force of rare earth permanent magnet materials, the manufacturing cost is low, the operation steps are simple, and the difficulty of production operation is reduced , will not affect the production efficiency of sintered NdFeB magnets, and does not require the use of liquid seals, and will not introduce other impurities.

Description

A sintered material box and method for improving the consistency of magnetic properties of rare earth permanent magnet materials

technical field

The invention relates to a technology for improving the consistency of magnetic properties of rare earth permanent magnet materials, in particular to a sintering material box and a method for improving the consistency of magnetic properties of rare earth permanent magnet materials.

Background technique

Sintered NdFeB magnets, as the third generation rare earth permanent magnet materials, are widely used in equipment in new energy vehicles, intelligent manufacturing, medical, aerospace and other high-tech fields due to their excellent magnetic properties. The sintered NdFeB magnets used in the equipment in the above high-tech fields are often a large number of small-sized blocks cut from large blanks. In order to ensure stable equipment performance, it is necessary to ensure that each sintered NdFeB magnet Consistency of magnetic properties of magnets. As far as the current industry development is concerned, the consistency of magnetic properties has not been well resolved. The poor consistency of magnetic properties is actually manifested in: the magnetic properties of different batches of sintered NdFeB magnets of the same brand are greatly different, or the same batch of sintered NdFeB magnets in the same furnace Second, the magnetic properties of blanks in different positions in the furnace are not small. Not only that, but also the magnetic properties of samples taken from different positions of the same sintered NdFeB magnet are different. Therefore, improving the consistency of the performance of sintered NdFeB products is an urgent problem for enterprises producing sintered NdFeB magnets.

During the preparation process of sintered NdFeB magnets, the blank needs to be protected by a material box during the process of entering the sintering furnace. If there is a gas exchange between the nitrogen in the material box and the outside air during the process of entering the furnace, there is a high probability that the product will be oxidized. However, if only the airtightness of the material box is considered, the gas release and volatilization in the deflation stage during the heating process will not be released in time, which will affect the shrinkage degree of the product and the compactness of the product, making the size of the blank after sintering inconsistent, which will lead to a significant decline in product performance. , so the exhaust function of the cartridge is equally important. Therefore, it is very important to study a sintered NdFeB material box and a sintering method to take into account the airtightness of the material box and the exhaust effect.

The Chinese invention patent with the publication number CN114054753A discloses a material box for sintering NdFeB and a sintering method. The material box includes a box body and a box cover. And at the bottom of the groove, there are several air grooves; the lower end of the lid is provided with a flange whose shape matches the groove. When sintering, the billet needs to be put into the material box, and the sealing liquid with low boiling point is poured into the groove. The liquid level is located above the upper end surface of the gas groove and the groove bottom of the groove, so that the flange is aligned with the groove and the box cover is closed. into the sintering furnace. The above-mentioned material box can take into account the airtightness and exhaust function. After sintering, the size of the sintered compact shrinks in a consistent manner, the size deviation of a single product is greatly reduced, and the product density is uniform. intrinsic coercive force) consistency. However, the operation steps are complicated and the operation is difficult, which affects the production efficiency, and the sealing liquid is easy to introduce impurities, and the manufacturing cost of the box body and the box cover is high.

Contents of the invention

One of the technical problems to be solved by the present invention is to provide a sintered material box that improves the consistency of magnetic properties of rare earth permanent magnet materials. While the coercive force is consistent, the manufacturing cost is low and the operation steps are simple, which reduces the difficulty of production operation, does not affect the production efficiency of sintered NdFeB magnets, does not need to use liquid seals, and does not introduce other impurities.

The technical solution adopted by the present invention to solve one of the above-mentioned technical problems is: a sintered material box for improving the consistency of magnetic properties of rare earth permanent magnet materials, including a rectangular box body with an upper end opening, and the rectangular box body passes through the front side plate, The rear side board, the left side board, the right side board and the bottom board are arranged and connected sequentially according to the directions of front, rear, left, right, and bottom. The front side board, the rear side board, the left side board, the A rectangular material chamber is formed between the right side plate and the bottom plate, a downwardly recessed first groove is provided in the middle of the upper end of the front side plate, and a downwardly recessed groove is provided in the middle of the upper end of the rear side plate. The second groove, the middle part of the upper end of the left side plate is provided with a third groove recessed downwards, and the middle part of the upper end of the right side plate is provided with a fourth groove recessed downwards.

The sections of the first groove, the second groove, the third groove and the fourth groove along the vertical direction are all isosceles trapezoidal, and the bottom of the isosceles trapezoid The bottom is located above its upper bottom. In this structure, when multiple sintering boxes are stacked, because the sintering boxes are full of products and the weight is heavy, the sintering boxes of the previous layer are usually placed on the top of the next layer of sintering boxes and then pushed forward, so that The upper layer of sintering material boxes and the lower layer of sintering material boxes are aligned and stacked up and down, and the cross-sections of the first groove, the second groove, the third groove and the fourth groove along the vertical direction are all isosceles trapezoids, which can avoid The upper layer of sintering material box is stuck during the push process, and the operation is faster and smoother.

The height of the cross section of the first groove, the second groove, the third groove and the fourth groove along the vertical direction is not more than 5 mm, and the first The difference between the lower bottom and the upper bottom of the vertical section of the groove, the second groove, the third groove and the fourth groove is no more than 50 mm, and the first The cross-sectional area of a groove is 1%-3% of the front side area of the rectangular material cavity, and the cross-sectional area of the second groove is 1% of the rear side area of the rectangular material cavity -3%, the cross-sectional area of the third groove is 1%-3% of the left side area of the rectangular cavity, and the cross-sectional area of the fourth groove is the rectangular 1%-3% of the area on the right side of the cavity.

The bottom of the bottom plate is provided with a first annular groove, the depth of the first annular groove is smaller than the first groove, the second groove, the third groove and the The depth of the fourth groove mentioned above, when a plurality of said sintering boxes are stacked up and down, the tops of the front side plate, rear side plate, left side plate and right side plate of the sintering box on the next layer are embedded in the The bottom of the sintering container on the upper layer is set in the first annular groove.

The described sintering box for improving the magnetic properties of rare earth permanent magnet materials also includes a cover plate, the bottom of the cover plate is provided with a second annular groove, and the depth of the second annular groove is less than the The depth of the first groove, the second groove, the third groove and the fourth groove, when the cover plate is arranged on the front side plate, the When above the rear side panel, the left side panel and the right side panel, the tops of the front side panel, the rear side panel, the left side panel and the right side panel Can be embedded in the second annular groove.

The length of the front side plate along the left and right direction ranges from 250-500mm, the height along the up-down direction ranges from 30-80mm, and the thickness range along the front-to-back direction is 5-12mm. The length of the left and right direction is equal to the length of the front side plate along the left and right direction, the height of the rear side plate along the up and down direction is equal to the height of the front side plate along the up and down direction, and the height of the rear side plate along the front and rear direction The thickness is equal to the thickness of the front side plate along the front and back direction; the length range of the left side plate along the front and back direction is 250-500mm, the height range along the up and down direction is 30-80mm, and the value range along the left and right direction The range of thickness is 5-12mm, the length of the right side plate along the front and rear direction is equal to the length of the left side plate along the front and rear direction, the height of the right side plate along the up and down direction is equal to the left side plate The height of the side plates along the up and down direction, and the thickness of the right side plate along the left and right directions are equal to the thickness of the left side plate along the left and right directions.

The material of the front side board, the rear side board, the left side board, the right side board and the bottom board is graphite or carbon fiber.

Compared with the prior art, the advantage of the sintering box of the present invention is that a downwardly recessed first groove is provided in the middle of the upper end of the front side plate of the sintering box, and a downwardly recessed first groove is provided in the middle of the upper end of the rear side plate. The second groove, the middle part of the upper end of the left side plate is provided with a third groove sunken downward, and the middle part of the upper end of the right side plate is provided with a fourth groove sunken downward, which effectively increases the exhaust passage of the blank during sintering , in the stage of a large amount of billet degassing, the impurity gas is discharged from the first groove, the second groove, the third groove and the fourth groove, which improves the exhaust efficiency and the uniformity of the billet exhaust at different positions, and reduces the The carbon content of the blank also improves the consistency of the carbon content of the blank, thereby improving the consistency of the intrinsic coercive force of the rare earth permanent magnet material of the NdFeB material. At the same time, the bottom of the bottom plate of the sintering box of the present invention is provided with a first groove, the cover plate of the sintering box is provided with a second annular groove, and the depths of the first annular groove and the second annular groove are smaller than the first groove, the second groove, the third groove and the fourth groove. The depth of the groove, when multiple sintering boxes are stacked on top of each other and the uppermost sintering box is covered with a cover plate, the front, rear, left and right sides of the uppermost sintering box The top of the top of the sintering box is embedded in the second annular groove on the cover plate, and the tops of the front side plate, rear side plate, left side plate and right side plate of the sintering box on the next layer are embedded in the upper layer. In the first annular groove provided at the bottom of the bottom plate of the one-layer sintering material box, in the process of entering the sintering furnace, it can avoid direct contact between the billet and the air in a large area, and take into account the airtightness. Therefore, the sintering material box of the present invention takes into account both The airtightness and exhaust function improve the consistency of the remanence and intrinsic coercive force of rare earth permanent magnet materials. At the same time, the manufacturing cost is low and the operation steps are simple, which reduces the difficulty of production operation and will not affect the production efficiency of sintered NdFeB magnets. , and does not require the use of liquid seals, and will not introduce other impurities. The second technical problem to be solved by the present invention is to provide a method for improving the consistency of magnetic properties of rare earth permanent magnet materials. In this method, by adjusting the sintering process, the degassing temperature of the deagent is changed from the original fixed temperature to a fluctuating temperature, and the deagent process of the NdFeB blank is increased, thereby improving the deagent effect, effectively removing impurities, and further improving the residual value of the rare earth permanent magnet material. The consistency of magnetism and intrinsic coercive force, and at the same time, the sintered material box is improved to make it take into account the airtightness and exhaust function, and improve the consistency of rare earth permanent magnet material remanence and intrinsic coercive force. The cost is low, the operation steps are simple, the difficulty of production operation is reduced, the production efficiency of sintered NdFeB magnets will not be affected, and impurities will not be introduced.

The technical solution adopted by the present invention to solve the above-mentioned technical problem 2 is: a method for improving the consistency of magnetic properties of rare earth permanent magnet materials, comprising the following steps:

(1) Prepare the material according to the formula of the rare earth permanent magnet material, and then obtain the casting sheet through the quick-setting flake technology;

(2) Hydrogen crush the casting to obtain coarse alloy powder, and then put the coarse alloy powder into a tank protected by inert gas for storage;

(3) Transfer the coarse alloy powder to the jet mill equipment for grinding to obtain a fine powder with a particle size D50 of 4.0 μm-4.5 μm, and then put the fine powder into a tank protected by an inert gas, wherein, in the jet mill During the milling process of the equipment, oxygen is supplemented according to the process requirements, and the online oxygen content of the jet mill equipment is kept between 0-50ppm;

(4) The fine powder is transferred to the molding workshop, and the fine powder is pressed and formed by a press to obtain a billet, and then the compact is packed in a vacuum packaging bag and sealed with a vacuum packaging machine, wherein, during the press molding process, the The interior of the press is always filled with inert gas to keep the oxygen content below 0.02%;

(5) Send the encapsulated billet into the sintering and peeling glove box after hydroisostatic pressing, and reduce the oxygen content in the sintering and peeling glove box to below 0.02%;

(6) In the sintering and peeling glove box, the blanks are stripped, and the blanks are taken out from the vacuum packaging bag and arranged in the sintering material box pre-placed in the sintering and peeling glove box. The sintering material The box includes a rectangular box body with an open upper end. The rectangular box body is composed of a front side panel, a rear side panel, a left side panel, a right side panel and a bottom panel according to the directions of front, rear, left, right, and bottom. The front side panel, the The rear side plate, the left side plate, the right side plate and the bottom plate are surrounded by a rectangular material cavity for arranging blanks, and the middle part of the upper end of the front side plate is provided with a The first groove is sunken down, the middle part of the upper end of the rear side plate is provided with the second groove sunken downwards, the middle part of the upper end of the left side plate is provided with the third groove sunken downwards, the The middle part of the upper end of the right side plate is provided with a fourth groove sunken downward;

(7) Under the atmosphere of nitrogen protection, the sintering boxes filled with blanks are first stacked up and down according to the furnace load, and a cover plate is put on the uppermost sintering box, and then the stacked sintering boxes are put into the furnace after the furnace The method is arranged in sequence in the sintering furnace cavity for high-temperature sintering. The high-temperature sintering process adopts the vibration sintering process. The specific process is: first raise the temperature for 20min-50min to 330°C-430°C, then repeat 2-5 times to cool down and then heat up process, then continue to heat up for 60min-120min to 540°C-650°C and hold for 1h-3h, then heat up for 60min-120min to 780°C-900°C and hold for 1h-3h, continue to heat up for 20min-50min to 900°C-980°C for 1h -3h, then increase the temperature for 30min-60min to 1000°C-1100°C and keep it warm for 3h-8h, and finally carry out subsequent aging treatment. The reheating process is as follows: first lower the temperature for 20min-50min, wherein the temperature drop range is 40°C-80°C, and then raise the temperature for 20min-50min to 330°C-430°C.

The sections of the first groove, the second groove, the third groove and the fourth groove along the vertical direction are all isosceles trapezoidal, and the bottom of the isosceles trapezoid The bottom is located above its upper bottom. The height of the cross section of the first groove, the second groove, the third groove and the fourth groove along the vertical direction is not more than 5 mm, and the first The difference between the lower bottom and the upper bottom of the vertical section of the groove, the second groove, the third groove and the fourth groove is no more than 50 mm, and the first The cross-sectional area of a groove is 1%-3% of the front side area of the rectangular material cavity, and the cross-sectional area of the second groove is 1% of the rear side area of the rectangular material cavity -3%, the cross-sectional area of the third groove is 1%-3% of the left side area of the rectangular cavity, and the cross-sectional area of the fourth groove is the rectangular 1%-3% of the area on the right side of the material cavity.

Compared with the existing patents, the method of the present invention has the advantage that a downwardly recessed first groove is provided at the upper end middle of the front side plate of the sintering box, and a downwardly recessed second groove is provided at the upper end middle of the rear side plate. Grooves, the middle part of the upper end of the left side plate is provided with a third groove that is sunken downwards, and the middle part of the upper end of the right side plate is provided with a fourth groove that is sunken downwards, which effectively increases the exhaust passage of the blank during sintering. In the stage of a large amount of billet degassing, impurity gases are discharged from the first groove, the second groove, the third groove and the fourth groove, which improves the exhaust efficiency and the uniformity of the billet exhaust at different positions, and reduces the carbon of the billet. content, also improves the consistency of the carbon content of the blank, thereby improving the consistency of the intrinsic coercive force of the rare earth permanent magnet material of the NdFeB material, and at the same time, the bottom of the bottom plate of the sintering box of the present invention is provided with a first annular groove , the cover plate of the sintering box is provided with a second annular groove, and the depths of the first annular groove and the second annular groove are smaller than the first groove, the second groove, the third groove and the fourth groove When a plurality of sintering boxes are stacked up and down and the uppermost sintering box is covered with a cover plate, the top of the front side plate, rear side plate, left side plate and right side plate of the uppermost sintering box Embedded in the second annular groove on the cover plate, in other layers of sintered material boxes, the top of the front side plate, rear side plate, left side plate and right side plate of the sintered material box on the next layer is embedded in the upper layer In the first annular groove set at the bottom of the bottom plate of the sintering material box, it can avoid direct contact between the billet and the air in a large area during entering the sintering furnace, taking into account the airtightness, and the stacked sintering material boxes are carried out after the furnace Furnace method (into the furnace after the furnace refers to: the stripping glove box is connected to the back door of the sintering furnace, the back door of the sintering furnace is opened, and the stacked sintering boxes in the stripping glove box are transferred to the sintering furnace under a nitrogen protective atmosphere), press Sequentially arranged in the sintering furnace cavity for high-temperature sintering, which ensures that the billets will not be exposed to air and will not be oxidized; in addition, sintered NdFeB magnets will be added with antioxidants and lubricants during the jet milling stage to ensure powder Additives that are not oxidized and help airflow milling, additives such as lubricants and release agents are also used in the stirring and forming stages to improve the formability of the powder and increase the orientation of the powder particles in the magnetic field. At present, there are various types of additives. The use of powder modifying additives will improve the performance of sintered NdFeB magnets, so the amount of powder modifying additives in the industry is also gradually increasing, but the above additives are a multi-component organic compound, which will introduce a large amount of If the excess C and O elements are not discharged in time, the performance of the NdFeB permanent magnet material will be affected. Therefore, the present invention further improves the sintering process to a vibration sintering process, specifically: first raise the temperature for 20min-50min to 330°C-430°C, then repeat the cooling and heating process 2-5 times, then continue to heat up for 60min-120min to 540°C-650°C and keep warm for 1h-3h, then heat up for 60min-120min to 780°C-900°C and keep warm for 1h -3h, continue to heat up for 20min-50min to 900°C-980°C for 1h-3h, then raise the temperature for 30min-60min to 1000°C-1100°C and hold for 3h-8h, and finally carry out subsequent aging treatment. For sintered NdFeB magnets, that is, rare earth permanent magnet materials, the process of cooling and heating each time is as follows: first cooling for 20min-50min, the cooling range is 40°C-80°C, and then heating for 20min-50min to 330°C-430°C. During the oscillating sintering process, C and O are discharged through the alternation of heating and cooling (the temperature stage of 330°C-430°C is the best temperature range for C and O discharge), so the present invention adjusts the sintering process to make the deagent The degassing temperature changes from the original fixed temperature to the fluctuating temperature, which increases the deagent process of the NdFeB green body, thereby improving the deagent effect, effectively removing impurities, and improving the consistency of the remanence and intrinsic coercive force of rare earth permanent magnet materials , combined with the improved sintering material box, it can take into account the airtightness and exhaust function, improve the consistency of the remanence and intrinsic coercive force of rare earth permanent magnet materials, and at the same time, the manufacturing cost is low, the operation steps are simple, and the The difficulty of production operation will not affect the production efficiency of sintered NdFeB magnets, and will not introduce impurities.

Description of drawings

Fig. 1 is the structure schematic diagram one of the sintered material box that improves the magnetic performance consistency of rare earth permanent magnet material of the present invention;

Fig. 2 is the structure schematic diagram two of the sintered material box that improves the magnetic performance consistency of rare earth permanent magnet material of the present invention;

Fig. 3 is the front view of the sintered charging box which improves the consistency of the magnetic properties of rare earth permanent magnet materials of the present invention;

Fig. 4 is the left side view of the sintered charging box which improves the consistency of the magnetic properties of rare earth permanent magnet materials of the present invention;

Fig. 5 is a top view of the sintered container for improving the consistency of magnetic properties of rare earth permanent magnet materials according to the present invention.

Detailed ways

The invention discloses a sintered material box for improving the consistency of magnetic properties of rare earth permanent magnet materials. The sintered material box of the invention will be further described in detail below with reference to the embodiments of the accompanying drawings.

Embodiment 1: As shown in Figures 1 to 5, a sintered material box that improves the consistency of the magnetic properties of rare earth permanent magnet materials includes a rectangular box with an upper end opening, and the rectangular box passes through the front side plate 1 and the rear side plate 2 , the left side plate 3, the right side plate 4 and the bottom plate 5 are arranged according to the directions of the front, rear, left, right, and bottom and are sequentially connected. Surrounded by a rectangular material cavity 6, the upper middle part of the front side plate 1 is provided with a downwardly recessed first groove 7, the upper end middle part of the rear side plate 2 is provided with a downwardly recessed second groove 8, the left side plate 3 A downwardly recessed third groove 9 is provided in the middle of the upper end, and a downwardly recessed fourth groove 10 is provided in the upper middle of the right side plate 4 .

In this embodiment, the material of the front side plate 1 , the rear side plate 2 , the left side plate 3 , the right side plate 4 and the bottom plate 5 is graphite.

Embodiment 2: This embodiment is basically the same as Embodiment 1, the difference is that in this embodiment, the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10 are along the vertical direction The cross-sections are all isosceles trapezoids, and the lower base of the isosceles trapezoids is above the upper base.

In this embodiment, the heights of the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10 along the vertical section are all 3mm, and the first groove 7, the second groove Groove 8, the 3rd groove 9 and the 4th groove 10 are along the bottom of the bottom of the section of vertical direction and the difference of upper bottom is 50mm, and the area of the section of the first groove 7 is the front side area of rectangular material cavity 6 1%, the cross-sectional area of the second groove 8 is 1% of the rear side area of the rectangular material chamber 6, the cross-sectional area of the third groove 9 is 1% of the left side area of the rectangular material chamber 6, the first The area of the cross section of the four grooves 10 is 1% of the area of the right side of the rectangular cavity 6 .

In this embodiment, the bottom of the bottom plate 5 is provided with a first annular groove 11, and the depth of the first annular groove 11 is smaller than that of the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10. When a plurality of sintering boxes are stacked up and down, the tops of the front side plate 1, rear side plate 2, left side plate 3 and right side plate 4 of the next layer of sintering boxes are embedded in the sintering boxes of the previous layer In the first annular groove 11 that the bottom of magazine is set.

In this embodiment, a kind of sintering box that improves the magnetic performance consistency of rare earth permanent magnet material also includes cover plate 12, and the bottom of cover plate 12 is provided with the second annular groove 13, and the depth of second annular groove 13 is less than the first The depth of a groove 7, the second groove 8, the third groove 9 and the fourth groove 10, when the cover plate 12 is arranged on the front side plate 1, the rear side plate 2, the left side plate 3 and the right side plate 4 When it is up, the tops of the front side plate 1, the rear side plate 2, the left side plate 3 and the right side plate 4 can be embedded in the second annular groove 13, and the material of the cover plate 12 is graphite.

In this embodiment, the length of the front side plate 1 along the left-right direction is 500 mm, the height along the up-down direction is 80 mm, and the thickness along the front-back direction is 5 mm. The length of the rear side plate 2 along the left-right direction is equal to that of the front side plate 1 The length of the direction, the height of the rear side plate 2 along the up and down direction is equal to the height of the front side plate 1 along the up and down direction, the thickness of the rear side plate 2 along the front and rear direction is equal to the thickness of the front side plate 1 along the front and rear direction; the left side plate 3 along the front and rear The length in the direction is 300mm, the height along the up-down direction is 80mm, and the thickness along the left-right direction is 5mm. The height is equal to the height of the left side plate 3 along the up-down direction, and the thickness of the right side plate 4 along the left-right direction is equal to the thickness of the left side plate 3 along the left-right direction.

Embodiment 3: This embodiment is basically the same as Embodiment 1, the difference is that in this embodiment, the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10 are along the vertical direction The cross-sections are all isosceles trapezoids, and the lower base of the isosceles trapezoids is above the upper base.

In this embodiment, the height of the cross section of the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10 along the vertical direction is 5mm, and the first groove 7, the second groove 8. The difference between the lower bottom and the upper bottom of the cross-section of the third groove 9 and the fourth groove 10 along the vertical direction is 50mm, and the area of the cross-section of the first groove 7 is the front side area of the rectangular material cavity 6 3%, the area of the cross section of the second groove 8 is 3% of the rear side area of the rectangular material chamber 6, the area of the cross section of the third groove 9 is 3% of the left side area of the rectangular material chamber 6, the fourth The cross-sectional area of the groove 10 is 3% of the area of the right side of the rectangular cavity 6 .

In this embodiment, the bottom of the bottom plate 5 is provided with a first annular groove 11, and the depth of the first annular groove 11 is smaller than that of the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10. When a plurality of sintering boxes are stacked up and down, the tops of the front side plate 1, rear side plate 2, left side plate 3 and right side plate 4 of the next layer of sintering boxes are embedded in the sintering boxes of the previous layer In the first annular groove 11 that the bottom of magazine is set.

In this embodiment, a kind of sintering box that improves the magnetic performance consistency of rare earth permanent magnet material also includes cover plate 12, and the bottom of cover plate 12 is provided with the second annular groove 13, and the depth of second annular groove 13 is less than the first The depth of a groove 7, the second groove 8, the third groove 9 and the fourth groove 10, when the cover plate 12 is arranged on the front side plate 1, the rear side plate 2, the left side plate 3 and the right side plate 4 When it is up, the tops of the front side plate 1, the rear side plate 2, the left side plate 3 and the right side plate 4 can be embedded in the second annular groove 13, and the material of the cover plate 12 is graphite.

In this embodiment, the length of the front side plate 1 along the left-right direction is 500mm, the height along the up-down direction is 80mm, and the thickness along the front-back direction is 5mm, and the length of the rear side plate 2 along the left-right direction is equal to that of the front side plate 1 The length of the rear side plate 2 along the up and down direction is equal to the height of the front side plate 1 along the up and down direction, the thickness of the back side plate 2 along the front and rear direction is equal to the thickness of the front side plate 1 along the front and rear direction; the left side plate 3 is along the front and rear direction The length is 300mm, the height along the up-down direction is 80mm, and the thickness along the left-right direction is 5mm. It is equal to the height of the left side plate 3 along the up-down direction, and the thickness of the right side plate 4 along the left-right direction is equal to the thickness of the left side plate 3 along the left-right direction.

The invention also discloses a method for improving the consistency of the magnetic properties of the rare earth permanent magnet material. The method of the invention will be further described in detail below in conjunction with the embodiments of the accompanying drawings.

Embodiment four: a method for improving the consistency of magnetic properties of rare earth permanent magnet materials, comprising the following steps:

(1) Prepare materials according to the formula of 42SH brand NdFeB magnets, and then obtain cast pieces through quick-setting flake technology;

(2) Hydrogen crush the casting to obtain coarse alloy powder, and then put the coarse alloy powder into a tank protected by inert gas for storage;

(3) Transfer the coarse alloy powder to the jet mill equipment for grinding to obtain a fine powder with a particle size D50 of 4.0 μm-4.5 μm, and then put the fine powder into a tank protected by an inert gas, wherein, in the jet mill During the milling process of the equipment, oxygen is supplemented according to the process requirements, and the online oxygen content of the jet mill equipment is kept between 0-50ppm;

(4) The fine powder is transferred to the molding workshop, and the fine powder is pressed and formed by a press to obtain a billet, and then the compact is packed in a vacuum packaging bag and sealed with a vacuum packaging machine, wherein, during the press molding process, the press The interior is always filled with inert gas to keep the oxygen content below 0.02%;

(5) Send the encapsulated billet into the sintering and peeling glove box after hydroisostatic pressing, and reduce the oxygen content in the sintering and peeling glove box to below 0.02%;

(6) In the sintering and stripping glove box, the blanks are stripped, and the blanks are taken out of the vacuum packaging bag and arranged in the sintering box pre-placed in the sintering stripping glove box, as shown in Figure 1 to As shown in 5, the sintering material box includes a rectangular box body with an open upper end. The rectangular box body is formed by splicing the front side plate 1, the rear side plate 2, the left side plate 3, the right side plate 4 and the bottom plate 5 according to the directions of front, back, left, right, and bottom. The front side plate 1, the rear side plate 2, the left side plate 3, the right side plate 4 and the bottom plate 5 enclose a rectangular material cavity 6 for arranging blanks, and the middle part of the upper end of the front side plate 1 is provided with a downward concave The first groove 7, the middle part of the upper end of the rear side plate 2 is provided with the second groove 8 sunken downwards, the middle part of the upper end of the left side plate 3 is provided with the third groove 9 sunken downwards, the upper end of the right side plate 4 The middle part is provided with a downwardly recessed fourth groove 10; the material of the front side plate 1, the rear side plate 2, the left side plate 3, the right side plate 4 and the bottom plate 5 is graphite;

(7) Under a nitrogen protection atmosphere, first stack the sintering boxes filled with blanks up and down according to the furnace load, and cover a cover plate 12 on the uppermost layer of the sintering material box. The material of the cover plate 12 is graphite, and then put The stacked sintering material boxes are arranged in sequence in the furnace cavity of the sintering furnace for high-temperature sintering by adopting the method of entering the furnace behind the furnace. The high-temperature sintering process adopts a vibration sintering process. The specific process is: first raise the temperature for 30 minutes to 430 ° C, and then repeat the temperature reduction for 3 times Reheating process, then continue to heat up for 90min to 600°C and hold for 1h, then heat up for 90min to 850°C and hold for 1h, continue to heat up for 40min to 960°C for 1.5h, then heat up for 30min to 1060°C and hold for 4h, and finally carry out subsequent aging After the aging treatment, the sintered NdFeB magnet, that is, the rare earth permanent magnet material, is obtained after the aging treatment is completed. The heating process of each cooling and heating is as follows: first cooling for 30 minutes to 350 ° C, and then heating for 30 minutes to 430 ° C.

In this embodiment, the cross-sections of the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10 along the vertical direction are all isosceles trapezoids, and the lower base of the isosceles trapezoids is located upper bottom.

In this embodiment, the height of the cross section of the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10 along the vertical direction is 3mm, and the first groove 7, the second groove 8. The difference between the lower bottom and the upper bottom of the cross-section of the third groove 9 and the fourth groove 10 along the vertical direction is 50mm, and the area of the cross-section of the first groove 7 is the front side area of the rectangular material cavity 6 1%, the area of the cross section of the second groove 8 is 1% of the rear side area of the rectangular material chamber 6, the area of the cross section of the third groove 9 is 1% of the left side area of the rectangular material chamber 6, the fourth The area of the cross section of the groove 10 is 1% of the area of the right side of the rectangular cavity 6 .

In this embodiment, the bottom of the bottom plate 5 is provided with a first annular groove 11, and the depth of the first annular groove 11 is smaller than that of the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10. When a plurality of sintering boxes are stacked up and down, the tops of the front side plate 1, rear side plate 2, left side plate 3 and right side plate 4 of the next layer of sintering boxes are embedded in the sintering boxes of the previous layer In the first annular groove 11 that the bottom of magazine is set.

In this embodiment, the bottom of the cover plate 12 is provided with a second annular groove 13, and the depth of the second annular groove 13 is smaller than that of the first groove 7, the second groove 8, the third groove 9 and the fourth groove. The depth of 10, when the cover plate 12 is arranged on the front side plate 1, the rear side plate 2, the left side plate 3 and the right side plate 4, the front side plate 1, the rear side plate 2, the left side plate 3 and the right side plate The top of 4 can be embedded in the second annular groove 13.

In this embodiment, the length of the front side plate 1 along the left-right direction is 500mm, the height along the up-down direction is 80mm, and the thickness along the front-back direction is 5mm, and the length of the rear side plate 2 along the left-right direction is equal to that of the front side plate 1 The length of the rear side plate 2 along the up and down direction is equal to the height of the front side plate 1 along the up and down direction, the thickness of the back side plate 2 along the front and rear direction is equal to the thickness of the front side plate 1 along the front and rear direction; the left side plate 3 is along the front and rear direction The length is 300mm, the height along the up-down direction is 80mm, and the thickness along the left-right direction is 5mm. It is equal to the height of the left side plate 3 along the up-down direction, and the thickness of the right side plate 4 along the left-right direction is equal to the thickness of the left side plate 3 along the left-right direction.

In this embodiment, during the high-temperature sintering process, various impurity gases in the blank can pass through the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10 in the sintering box more quickly and discharged evenly. After the sintered NdFeB magnets were released from the furnace, 8 pieces were randomly selected as samples to test the magnetic properties and carbon content. The specific data are shown in Table 1.

Comparative example 1: This comparative example adopts a conventional sintering process, and does not use the sintering material box of Example 4, but uses a conventional material box, and other processes are the same as in Example 4. After the sintered NdFeB magnets of Comparative Example 1 were released from the furnace, 8 pieces were randomly selected as samples to test the magnetic properties and carbon content. The specific data are shown in Table 2.

Table 1: Magnetic properties of the sample of Example 4

Table 2: Magnetic properties of samples of Comparative Example 1

Analysis of the data in Table 1 and Table 2 shows that the maximum remanence of the sample in Example 4 is 13.39 kGs, the minimum remanence is 13.31 kGs, the difference (Δ B _r ) is 0.08 kGs, and the maximum intrinsic coercive force H _cJ is is 20.60 kOe, the minimum value of H _cJ is 20.24 kOe, and the difference (Δ H _cJ ) is 0.36 kOe. The maximum remanence of the sample of Comparative Example 1 is 13.37 kGs, the minimum remanence is 13.12kGs, the difference (Δ B _r ) is 0.25kGs, the maximum value of intrinsic coercive force H _cJ is 20.54 kOe, and the minimum value of H _cJ is 19.82kOe, the difference ( ΔH _cJ ) is 0.72kOe. It can be seen that the consistency of remanence and coercive force of the blank in Example 4 is improved, and the carbon content is lower, and the consistency of carbon content is also significantly improved, which generally improves the consistency of the magnetic properties of the sintered NdFeB magnet.

Embodiment five: a method for improving the consistency of magnetic properties of rare earth permanent magnet materials, comprising the following steps:

(1) Prepare materials according to the formula of 45SH brand NdFeB magnets, and then obtain cast pieces by quick-setting flake technology;

(2) Hydrogen crush the casting to obtain coarse alloy powder, and then put the coarse alloy powder into a tank protected by inert gas for storage;

(3) Transfer the coarse alloy powder to the jet mill equipment for grinding to obtain a fine powder with a particle size D50 of 4.0 μm-4.5 μm, and then put the fine powder into a tank protected by an inert gas, wherein, in the jet mill During the milling process of the equipment, oxygen is supplemented according to the process requirements, and the online oxygen content of the jet mill equipment is kept between 0-50ppm;

(4) The fine powder is transferred to the molding workshop, and the fine powder is pressed and formed by a press to obtain a billet, and then the compact is packed in a vacuum packaging bag and sealed with a vacuum packaging machine, wherein, during the press molding process, the press The interior is always filled with inert gas to keep the oxygen content below 0.02%;

(5) Send the encapsulated billet into the sintering and peeling glove box after hydroisostatic pressing, and reduce the oxygen content in the sintering and peeling glove box to below 0.02%;

(6) In the sintering and stripping glove box, the blanks are stripped, and the blanks are taken out of the vacuum packaging bag and arranged in the sintering box pre-placed in the sintering stripping glove box, as shown in Figure 1 to As shown in 5, the sintering material box includes a rectangular box body with an open upper end. The rectangular box body is formed by splicing the front side plate 1, the rear side plate 2, the left side plate 3, the right side plate 4 and the bottom plate 5 according to the directions of front, back, left, right, and bottom. The front side plate 1, the rear side plate 2, the left side plate 3, the right side plate 4 and the bottom plate 5 enclose a rectangular material cavity 6 for arranging blanks, and the middle part of the upper end of the front side plate 1 is provided with a downward concave The first groove 7, the middle part of the upper end of the rear side plate 2 is provided with the second groove 8 sunken downwards, the middle part of the upper end of the left side plate 3 is provided with the third groove 9 sunken downwards, the upper end of the right side plate 4 The middle part is provided with a fourth groove 10 sunken downward;

(7) Under a nitrogen protection atmosphere, first stack the sintering boxes filled with blanks up and down according to the furnace load, and cover a cover plate 12 on the uppermost layer of the sintering material box. The material of the cover plate 12 is graphite, and then put The stacked sintering material boxes are arranged in sequence in the furnace cavity of the sintering furnace for high-temperature sintering by adopting the method of entering the furnace behind the furnace. The high-temperature sintering process adopts a vibration sintering process. The specific process is: first raise the temperature for 30 minutes to 430 ° C, and then repeat the temperature reduction for 3 times Reheating process, then continue to heat up for 90min to 600°C and hold for 1h, then heat up for 90min to 850°C and hold for 2h, continue to heat up for 40min to 960°C for 1.5h, then heat up for 30min to 1060°C and hold for 4h, and finally carry out subsequent aging After the aging treatment, the sintered NdFeB magnet, that is, the rare earth permanent magnet material, is obtained after the aging treatment is completed. The heating process of each cooling and heating is as follows: first cooling for 30 minutes to 350 ° C, and then heating for 30 minutes to 430 ° C.

In this embodiment, the cross-sections of the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10 along the vertical direction are all isosceles trapezoids, and the lower base of the isosceles trapezoids is located upper bottom.

In this embodiment, the height of the cross section of the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10 along the vertical direction is 3mm, and the first groove 7, the second groove 8. The difference between the lower bottom and the upper bottom of the cross-section of the third groove 9 and the fourth groove 10 along the vertical direction is 50mm, and the area of the cross-section of the first groove 7 is the front side area of the rectangular material cavity 6 1%, the area of the cross section of the second groove 8 is 1% of the rear side area of the rectangular material chamber 6, the area of the cross section of the third groove 9 is 1% of the left side area of the rectangular material chamber 6, the fourth The area of the cross section of the groove 10 is 1% of the area of the right side of the rectangular cavity 6 .

In this embodiment, the bottom of the bottom plate 5 is provided with a first annular groove 11, and the depth of the first annular groove 11 is smaller than that of the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10. When a plurality of sintering boxes are stacked up and down, the tops of the front side plate 1, rear side plate 2, left side plate 3 and right side plate 4 of the next layer of sintering boxes are embedded in the sintering boxes of the previous layer In the first annular groove 11 that the bottom of magazine is set.

In this embodiment, the bottom of the cover plate 12 is provided with a second annular groove 13, and the depth of the second annular groove 13 is smaller than that of the first groove 7, the second groove 8, the third groove 9 and the fourth groove. The depth of 10, when the cover plate 12 is arranged on the front side plate 1, the rear side plate 2, the left side plate 3 and the right side plate 4, the front side plate 1, the rear side plate 2, the left side plate 3 and the right side plate The top of 4 can be embedded in the second annular groove 13.

In this embodiment, the length of the front side plate 1 along the left-right direction is 500mm, the height along the up-down direction is 80mm, and the thickness along the front-back direction is 5mm, and the length of the rear side plate 2 along the left-right direction is equal to that of the front side plate 1 The length of the rear side plate 2 along the up and down direction is equal to the height of the front side plate 1 along the up and down direction, the thickness of the back side plate 2 along the front and rear direction is equal to the thickness of the front side plate 1 along the front and rear direction; the left side plate 3 is along the front and rear direction The length is 300mm, the height along the up-down direction is 80mm, and the thickness along the left-right direction is 5mm. It is equal to the height of the left side plate 3 along the up-down direction, and the thickness of the right side plate 4 along the left-right direction is equal to the thickness of the left side plate 3 along the left-right direction.

In this embodiment, during the high-temperature sintering process, various impurity gases in the blank can pass through the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10 in the sintering box more quickly and discharged evenly. After the sintered NdFeB magnets were released from the furnace, 8 pieces were randomly selected as samples to test the magnetic properties and carbon content. The specific data are shown in Table 3.

Comparative example 2: In this comparative example, the sintering material box of the fifth embodiment is used, but a conventional sintering process is adopted. After the sintered NdFeB magnets of Comparative Example 2 were released from the furnace, 8 pieces were randomly selected as samples to test the magnetic properties and carbon content. The specific data are shown in Table 4.

Table 3: Magnetic properties of the sample of Example 5

Table 4: Magnetic properties of the sample of Comparative Example 2

Analysis of the data in Table 3 and Table 4 shows that the maximum remanence of the sample in Example 5 is 13.65 kGs, the minimum remanence is 13.51 kGs, and the difference (Δ B _r ) is 0.14 kGs. The maximum intrinsic coercivity H _cJ is 21.95kOe, the minimum H _cJ is 21.62kOe, and the difference (Δ H _cJ ) is 0.33kOe. The maximum remanence of the sample in Comparative Example 2 was 13.61kGs, the minimum remanence was 13.40kGs, and the difference (Δ B _r ) was 0.21kGs. The maximum intrinsic coercive force H _cJ is 22.27kOe, the minimum H _cJ is 21.39kOe, and the difference (Δ H _cJ ) is 0.88kOe. At this time, the oxygen content of the sample is generally increased, and the sample is easily oxidized, resulting in poor magnetic properties. dropped. It can be seen that the sintering process combined with the appropriate range of the height of the cross section of the first groove 7, the second groove 8, the third groove 9 and the fourth groove 10 along the vertical direction can make the sintered NdFeB magnet remain The consistency of magnetism and coercive force is improved, and the carbon content is lower, and the consistency of carbon content is also significantly improved, which generally improves the consistency of the magnetic properties of sintered NdFeB magnets.

Claims (10)

1. The utility model provides an improve sintering magazine of tombarthite permanent magnet material magnetism performance uniformity, its characterized in that includes upper end open-ended rectangle box body, rectangle box body pass through preceding curb plate, posterior lateral plate, left side board, right side board and bottom plate and arrange and connect gradually the constitution according to the position of controlling down, preceding curb plate posterior lateral plate left side board right side board and the bottom plate between enclose into rectangular material chamber, the upper end middle part of preceding curb plate be provided with the first recess of undercut, the upper end middle part of posterior lateral plate be provided with the second recess of undercut, the upper end middle part of left side board be provided with the third recess of undercut, the upper end middle part of right side board be provided with the fourth recess of undercut.

2. The sintering material box for improving the consistency of the magnetic properties of rare earth permanent magnetic materials according to claim 1, wherein the cross sections of the first groove, the second groove, the third groove and the fourth groove along the vertical direction are isosceles trapezoids, and the lower bottoms of the isosceles trapezoids are positioned above the upper bottoms of the isosceles trapezoids.

3. The sintering material box for improving the consistency of magnetic properties of rare earth permanent magnetic materials according to claim 2, wherein the heights of the cross sections of the first groove, the second groove, the third groove and the fourth groove along the vertical direction are not more than 5mm, the differences between the bottoms and the bottoms of the cross sections of the first groove, the second groove, the third groove and the fourth groove along the vertical direction are not more than 50mm, the area of the cross section of the first groove is 1% -3% of the area of the front side surface of the rectangular material cavity, the area of the cross section of the second groove is 1% -3% of the area of the rear side surface of the rectangular material cavity, the area of the cross section of the third groove is 1% -3% of the area of the left side surface of the rectangular material cavity, and the area of the cross section of the fourth groove is 1% -3% of the area of the right side surface of the rectangular material cavity.

4. The sintering material box for improving the consistency of the magnetic properties of rare earth permanent magnetic materials according to claim 1, wherein a first annular groove is formed in the bottom of the bottom plate, the depth of the first annular groove is smaller than the depth of the first groove, the depth of the second groove, the depth of the third groove and the depth of the fourth groove, and when a plurality of sintering material boxes are stacked up and down, the tops of the front side plate, the rear side plate, the left side plate and the right side plate of the sintering material box positioned in the next layer are embedded into the first annular groove formed in the bottom of the sintering material box positioned in the previous layer.

5. The sintering material box for improving the consistency of the magnetic properties of rare earth permanent magnetic materials according to claim 1, further comprising a cover plate, wherein a second annular groove is formed in the bottom of the cover plate, the depth of the second annular groove is smaller than the depth of the first groove, the second groove, the third groove and the fourth groove, and when the cover plate is arranged above the front side plate, the rear side plate, the left side plate and the right side plate, the tops of the front side plate, the rear side plate, the left side plate and the right side plate can be embedded into the second annular groove.

6. The sintering material box for improving the consistency of the magnetic properties of rare earth permanent magnetic materials according to claim 1, wherein the length of the front side plate along the left-right direction is 250-500mm, the height of the front side plate along the up-down direction is 30-80mm, the thickness of the rear side plate along the left-right direction is 5-12mm, the height of the rear side plate along the up-down direction is equal to the height of the front side plate along the up-down direction, and the thickness of the rear side plate along the front-rear direction is equal to the thickness of the front side plate along the front-rear direction; the length of the left side plate along the front-back direction is 250-500mm, the height of the left side plate along the up-down direction is 30-80mm, the thickness of the right side plate along the left-right direction is 5-12mm, the length of the right side plate along the front-back direction is equal to the length of the left side plate along the front-back direction, the height of the right side plate along the up-down direction is equal to the height of the left side plate along the up-down direction, and the thickness of the right side plate along the left-right direction is equal to the thickness of the left side plate along the left-right direction.

7. The sintering material box for improving the consistency of the magnetic properties of rare earth permanent magnetic materials according to claim 1, wherein the front side plate, the rear side plate, the left side plate, the right side plate and the bottom plate are made of graphite or carbon fiber.

8. A method for improving consistency of magnetic properties of rare earth permanent magnet materials is characterized by comprising the following steps:

(1) Preparing a material according to a formula of the rare earth permanent magnet material, and obtaining a cast sheet through a rapid hardening and sheet throwing technology;

(2) Hydrogen crushing the cast sheet to obtain alloy coarse powder, and then filling the alloy coarse powder into a tank body protected by inert gas for preservation;

(3) Transferring the alloy coarse powder into an air flow grinding device for grinding to obtain fine powder with the granularity D50 of 4.0-4.5 mu m, and then filling the fine powder into a tank body protected by inert gas, wherein oxygen supplementing is carried out according to the process requirements during the grinding process of the air flow grinding device, and the online oxygen content of the air flow grinding device is kept between 0 and 50 ppm;

(4) Transferring the fine powder to a forming workshop, performing compression forming on the fine powder through a press to obtain a blank, packaging the blank with a vacuum packaging bag, and packaging with a vacuum packaging machine, wherein inert gas is always filled into the press in the compression forming process, and the oxygen content is always lower than 0.02%;

(5) The packaged blank is sent into a sintering film stripping glove box after being subjected to water isostatic pressing treatment, and the oxygen content in the sintering film stripping glove box is reduced to below 0.02 percent;

(6) In a sintering film stripping glove box, film stripping treatment is carried out on blanks, the blanks are taken out from a vacuum packaging bag and then are arranged in a sintering material box which is placed in the sintering film stripping glove box in advance, the sintering material box comprises a rectangular box body with an opening at the upper end, the rectangular box body is formed by splicing a front side plate, a rear side plate, a left side plate, a right side plate and a bottom plate according to the directions of front, rear, left and right sides, rectangular material cavities for arranging the blanks are formed between the front side plate, the rear side plate, the right side plate and the bottom plate in a surrounding manner, a first concave groove which is downwards concave is formed in the middle of the upper end of the front side plate, a second concave groove which is downwards concave is formed in the middle of the upper end of the rear side plate, a third concave groove which is downwards concave is formed in the middle of the upper end of the left side plate, and a fourth concave groove which is downwards concave is formed in the middle of the upper end of the right side plate;

(7) Under the protection of nitrogen, stacking the sintering material boxes filled with blanks up and down according to the furnace loading amount, covering a cover plate on the uppermost sintering material box, and then orderly arranging the stacked sintering material boxes in a furnace chamber of a sintering furnace for high-temperature sintering in a furnace back feeding mode, wherein the high-temperature sintering process adopts a vibration sintering process, and the specific process is as follows: heating for 20min-50min to 330-430 ℃, then repeating the cooling and heating process for 2-5 times, then continuously heating for 60min-120min to 540-650 ℃ and preserving heat for 1h-3h, then heating for 60min-120min to 780-900 ℃ and preserving heat for 1h-3h, continuously heating for 20min-50min to 900-980 ℃ and preserving heat for 1h-3h, then continuously heating for 30min-60min to 1000-1100 ℃ and preserving heat for 3h-8h, finally performing subsequent aging treatment, and discharging after the aging treatment is finished to obtain a sintered neodymium iron boron magnet, namely a rare earth permanent magnet material, wherein the cooling and heating process each time is as follows: firstly cooling for 20min-50min, wherein the cooling amplitude is 40-80 ℃, and then heating for 20min-50min to 330-430 ℃.

9. The method for improving the consistency of magnetic properties of rare earth permanent magnetic materials according to claim 8, wherein the cross sections of the first groove, the second groove, the third groove and the fourth groove along the vertical direction are isosceles trapezoids, and the lower bottoms of the isosceles trapezoids are positioned above the upper bottoms of the first groove, the second groove, the third groove and the fourth groove.

10. The method for improving the magnetic property consistency of rare earth permanent magnet materials according to claim 8, wherein the heights of the cross sections of the first groove, the second groove, the third groove and the fourth groove in the vertical direction are not more than 5mm, the differences between the bottoms and the bottoms of the cross sections of the first groove, the second groove, the third groove and the fourth groove in the vertical direction are not more than 50mm, the area of the cross section of the first groove is 1% -3% of the area of the front side surface of the rectangular material cavity, the area of the cross section of the second groove is 1% -3% of the area of the rear side surface of the rectangular material cavity, the area of the cross section of the third groove is 1% -3% of the area of the left side surface of the rectangular material cavity, and the area of the cross section of the fourth groove is 1% -3% of the area of the right side surface of the rectangular material cavity.