Stable sintered neodymium-iron-boron magnet assembly

Abstract

The utility model relates to the technical field of rare earth magnets, and provides a stable sintered neodymium-iron-boron magnet assembly which comprises a sintered neodymium-iron-boron magnet and a protection part, and the protection part comprises a first protection piece and a second protection piece which are oppositely arranged on the two sides of the sintered neodymium-iron-boron magnet. An injection molding layer is arranged between the sintered neodymium-iron-boron magnet and the protection part, at least one injection molding hole communicated with the injection molding layer is formed in the surface of the protection part, and at least one groove is formed in the position, connected with the injection molding layer, of the sintered neodymium-iron-boron magnet. According to the sintered neodymium iron boron magnet assembly, injection molding connection is adopted, all the structures are firmly connected, the high-temperature resistance and stability of the sintered neodymium iron boron magnet assembly are improved, the sintered neodymium iron boron magnet assembly can be applied to the high-temperature severe environment, and meanwhile the assembly is simple in structure, simple in component and convenient to machine.

Description

Technical Field

[0001] The utility model relates to the technical field of rare earth magnets, in particular to a stable sintered NdFeB magnet assembly. Background Art

[0002] Sintered NdFeB magnets have excellent magnetic properties such as high remanence, high coercivity and high magnetic energy product, and are widely used in many fields such as new energy vehicles, variable frequency energy-saving home appliances, and wind power generation. Since the sintered NdFeB permanent magnet material adopts the powder metallurgy process, the strength of the finished product is poor, so a protective layer is usually set on the outside of the sintered NdFeB magnet, and the connection method is mostly to use glue for connection. However, this type of product has high requirements for working temperature and working environment. If used in a high temperature and harsh environment, the glue will melt, causing the connection between the magnet and the protective layer to loosen and fall off, resulting in the collapse or even fragmentation of the magnet, which greatly limits the application scope of the sintered NdFeB magnet. At the same time, because of its strong magnetism, the sintered NdFeB magnet can only be combined with the protective layer with glue after sintering into a finished magnet. The process is cumbersome and the assembly efficiency is low. Therefore, it is very important to develop an easy-to-assemble sintered NdFeB magnet component that can adapt to high temperature and harsh environment, has high stability and is not easy to fall off. Utility Model Content

[0003] In order to solve the technical problems of poor adhesion between the sintered NdFeB magnet and the protective layer and complicated assembly, the utility model provides a stable sintered NdFeB magnet assembly, which has a firm connection, high stability, a wide range of applications, a simple structure and easy assembly, and is convenient for industrial assembly line production.

[0004] The specific technical solution of the utility model is: a stable sintered NdFeB magnet assembly, including a sintered NdFeB magnet and a protective part, the protective part including a first protective part and a second protective part relatively arranged on both sides of the sintered NdFeB magnet, and a third protective part arranged at the bottom of the first protective part and the second protective part, an injection molding layer is provided between the sintered NdFeB magnet and the protective part, at least one injection molding hole connected to the injection molding layer is provided on the surface of the protective part, and at least one groove is provided on the sintered NdFeB magnet at the connection with the injection molding layer.

[0005] The protective part is set on the periphery of the sintered NdFeB magnet, which can well protect the magnet and will not break even if it falls. The sintered NdFeB magnet and the protective part are combined by injection molding, and the connection is firm. The plastic is resistant to high temperature and will not loosen under harsh conditions, ensuring the consistency and stability of the component connection to expand the application range of the sintered NdFeB magnet. The protective part is an integral structure or a separate structure.

[0006] Preferably, the groove is a through hole horizontally penetrating the side of the sintered NdFeB magnet or an annular groove surrounding the sintered NdFeB magnet, and the groove notch width is not less than the groove bottom width.

[0007] The groove is a horizontal through hole or annular groove with a large filling area and high filling efficiency. The groove can increase the ejection force of the sintered NdFeB magnet and the protective part after the plastic particles are injected.

[0008] Preferably, the groove depth is less than 1 / 4 of the diameter of the sintered NdFeB magnet, and the slot width is not greater than 1 / 4 of the height of the sintered NdFeB magnet.

[0009] The groove size should be controlled within a reasonable range. If it is too large, it will destroy the strength of the sintered NdFeB magnet and make it easy to break.

[0010] Preferably, the groove is arranged between the center position and the lower third position of the height of the sintered NdFeB magnet.

[0011] The first and second protective members are arranged above the groove, and the groove is arranged in the middle and lower part of the side of the sintered NdFeB magnet, so that there is enough area in the middle and upper part of the side of the sintered NdFeB magnet to arrange the first and second protective members, ensuring that the protective part can play a protective role.

[0012] Preferably, the groove cross-section is a "U"-shaped or arc-shaped structure.

[0013] The structure of the groove is conducive to the plastic particles to smoothly enter the groove and fill it up without leaving any gaps.

[0014] Preferably, the injection molding layer consists of a longitudinal injection molding layer surrounding the side wall of the sintered NdFeB magnet, a horizontal injection molding layer located at the bottom of the longitudinal injection molding layer, an outer injection molding layer connected to the injection molding hole, and an inner injection molding layer connected to the groove, and the thickness of the injection molding layer is not less than 5.0 mm.

[0015] The injection molding layer is divided into four parts. The plastic particles are injected through the injection molding hole to form the outer injection molding layer, and then pass through the connection between the sintered NdFeB magnet and the protection part to form the longitudinal injection molding layer and the horizontal injection molding layer, and finally enter the groove to form the inner injection molding layer. The injection molding layer firmly connects the protection part and the sintered NdFeB magnet, is fully filled, and has a simple process.

[0016] Preferably, the sintered NdFeB magnet has a symmetrical structure; the first protective member and the second protective member have the same structure and are symmetrically arranged on both sides of the sintered NdFeB magnet, and the tops of the three are in the same plane; the third protective member is symmetrical along the central axis of the sintered NdFeB magnet; and the sides of the protective part are flush.

[0017] The sintered NdFeB magnet has a symmetrical structure and high stability. At the same time, the structure has a smooth appearance and is easy to process.

[0018] Preferably, the volume of the sintered NdFeB magnet is smaller than the volume of the protection part.

[0019] This structure makes the sintered NdFeB magnet have better impact resistance.

[0020] Preferably, the upper parts of the first and second protective members are in direct contact with the upper side walls of the sintered NdFeB magnet, and the lower parts are connected to the lower side walls of the sintered NdFeB magnet via a longitudinal injection molding layer; the top of the third protective member is connected to the bottom surface of the sintered NdFeB magnet via a horizontal injection molding layer.

[0021] The protective part is connected to the sintered NdFeB magnet in a semi-enclosed shape, which can well protect the magnet. The first protective member, the second protective member and the third protective member are an integral or separate structure. The first protective member and the second protective member are partially connected to the sintered NdFeB magnet through an injection molding layer, and partially directly connected to the magnet. The injection molding layer is fully filled, the connection is firm, and the process is simple.

[0022] Preferably, the protection portion is made of non-magnetic metal.

[0023] Non-magnetic metals have high strength and will not affect the performance of sintered NdFeB magnets.

[0024] Compared with the prior art, the utility model has the following advantages:

[0025] (1) Stable structure and wide application range. The sintered NdFeB magnet and the protective part are connected by injection molding, which has a firm connection, good high temperature resistance, and will not loosen under harsh conditions, expanding the application range of sintered NdFeB magnets; grooves are set on both sides of the sintered NdFeB magnet to increase the ejection force of the sintered NdFeB magnet and the protective part after the plastic particles are injected.

[0026] (2) Simple structure and easy assembly. It adopts a symmetrical structure, streamlined parts, smooth appearance, and easy processing; it adopts injection molding connection and high assembly efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is an exploded view of Embodiment 1 and Embodiment 2 of the present utility model.

[0028] Figure 2 It is a cross-sectional view of Embodiment 1 and Embodiment 2 of the present invention.

[0029] Figure 3 It is a schematic diagram of the structure of the sintered NdFeB magnet in Examples 3 to 5 of the present invention.

[0030] The figures are marked as: 1-sintered NdFeB magnet, 2-first protective piece, 3-injection molding hole, 4-injection molding layer, 4.1-longitudinal injection molding layer, 4.2-horizontal injection molding layer, 4.3-outer injection molding layer, 4.4-inner injection molding layer, 5-third protective piece, 6-second protective piece, 7-groove. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the embodiments. The devices, connection structures and methods involved in the present invention are all devices, connection structures and methods known in the art unless otherwise specified.

[0032] Example 1

[0033] This embodiment provides a stable sintered NdFeB magnet assembly. Figure 1-2 It is understood that it includes a sintered NdFeB magnet 1 and a protection part, the protection part includes a first protection member 2 and a second protection member 6 relatively arranged on the outside of the sintered NdFeB magnet 1, and a third protection member 5 arranged at the bottom of the sintered NdFeB magnet. The protection part surrounds the sintered NdFeB magnet 1 in a semi-enclosed shape. The first protection member 2 and the second protection member 6 have the same structure, and the top of the two is in the same horizontal plane as the top of the sintered NdFeB magnet 1. The side of the third protection part 5 is aligned with the side of the first protection member 2 and the second protection member 6. The first protection member 2, the second protection member 6 and the third protection member 5 are three separate parts. Two symmetrical grooves 7 are provided at the lower three equal parts on both sides of the sintered NdFeB magnet 1. The groove 7 is a through hole that horizontally penetrates the side of the sintered NdFeB magnet 1. The height is 2.0 cm, the depth is 2.8 cm, the width of the notch is 1.1 cm, the width of the groove bottom is less than the width of the notch, and the cross section is "U" shaped. The sintered NdFeB magnet 1 is connected to the protection part by injection molding, and an injection molding layer 4 is arranged between the two. The surface of the protection part is provided with two injection molding holes 3 connected to the injection molding layer 4. The injection molding hole 3 is set at a height of 13 cm, and its opening area is larger than the groove notch area. The injection molding layer 4 is composed of a longitudinal injection molding layer 4.1 surrounding the side wall of the sintered NdFeB magnet 1, a horizontal injection molding layer 4.2 located at the bottom of the longitudinal injection molding layer 4.1, an outer injection molding layer 4.3 connected to the injection molding hole 3, and an inner injection molding layer 4.4 connected to the groove 7. The upper part of the first protection member 2 and the second protection member 6 are in direct contact with the upper side wall of the sintered NdFeB magnet 1, and the lower part is connected to the lower side wall of the sintered NdFeB magnet through the longitudinal injection molding layer 4.1; the top of the third protection member 5 is connected to the bottom surface of the sintered NdFeB magnet through the horizontal injection molding layer 4.2; the thickness of the injection molding layer 4 is 5.0 mm. The groove 7 is located at the connection between the two sides of the sintered NdFeB magnet 1 and the longitudinal injection layer 4.1. The sintered NdFeB magnet 1 is a cylindrical structure with a diameter of 12 cm and a height of 6.0 cm. Its volume is smaller than the volume of the protection part. The sintered NdFeB magnet is a cylindrical structure as a whole with a diameter of 20 cm and a height of 18 cm. The material of the protection part is stainless steel.

[0034] In the present embodiment, a protection part is provided, the purpose is to improve the impact resistance of the sintered NdFeB magnet, even if the magnet falls, it will not break, and it plays a role in protecting the magnet. The sintered NdFeB magnet 1 and the protection part are combined by injection molding, the purpose is that the method is firmly connected, and the plastic is resistant to high temperature, so that the sintered NdFeB magnet assembly will not be loosened under harsh conditions, which expands the scope of use of the sintered NdFeB magnet. At the same time, the injection molding is convenient for assembly and improves production efficiency. Grooves 7 are provided on both sides of the sintered NdFeB magnet 1, the purpose is to increase the ejection force after the sintered NdFeB magnet and the protection part are combined and injected with plastic particles. Injection holes 3 are provided, the purpose is to fill the injection layer with plastic particles, and inject them into the grooves 7. The protection part is made of stainless steel, which has high strength and will not affect the performance of the sintered NdFeB magnet. The sintered NdFeB magnet assembly adopts a symmetrical structure, high stability, streamlined components, and is easy to process.

[0035] The preparation method of the stable sintered NdFeB magnet assembly described in this embodiment includes the following steps: first, the injection molding machine is debugged and the injection mold is heated, the sintered NdFeB magnet 1 is placed in the injection mold, and then the protective part is placed in the injection mold, and the plastic material is put into the injection molding machine for injection molding, and the plastic particles fill the injection layer 4 and the groove 7 through the injection hole 3, completing the combination of the sintered NdFeB magnet 1 and the protective part. After the sintered NdFeB magnet assembly is combined, the finished product can be cooled to make the injection layer 4 solidify more thoroughly to ensure that the assembly is not loose.

[0036] Example 2

[0037] This embodiment provides a stable sintered NdFeB magnet assembly. Figure 1-2It is understood that it includes a sintered NdFeB magnet 1 and a protection part, the protection part includes a first protection member 2 and a second protection member 6 relatively arranged on the outside of the sintered NdFeB magnet 1, and a third protection member 5 arranged at the bottom of the sintered NdFeB magnet. The protection part surrounds the sintered NdFeB magnet 1 in a semi-enclosed shape. The first protection member 2 and the second protection member 6 have the same structure, and the top of the two is in the same horizontal plane as the top of the sintered NdFeB magnet 1. The side of the third protection member 5 is aligned with the side of the first protection member 2 and the second protection member 6. The first protection member 2, the second protection member 6 and the third protection member 5 are an integrated structure. Two symmetrical grooves 7 are provided at the center of both sides of the sintered NdFeB magnet 1. The groove 7 is a through hole that horizontally penetrates the side of the sintered NdFeB magnet 1, and its height is 3.0 cm, the depth is 2.0 cm, the width of the notch is 1.3 cm, the width of the groove bottom is less than the width of the notch, and the cross section is an arc shape. The sintered NdFeB magnet 1 is connected to the protection part by injection molding, and an injection molding layer 4 is arranged between the two. The surface of the protection part is provided with two injection molding holes 3 connected to the injection molding layer 4. The injection molding hole 3 is set at a height of 13 cm, and its opening area is equal to the groove notch area. The injection molding layer 4 is composed of a longitudinal injection molding layer 4.1 surrounding the side wall of the sintered NdFeB magnet 1, a horizontal injection molding layer 4.2 located at the bottom of the longitudinal injection molding layer 4.1, an outer injection molding layer 4.3 connected to the injection molding hole 3, and an inner injection molding layer 4.4 connected to the groove 7. The upper part of the first protection member 2 and the second protection member 6 are in direct contact with the upper side wall of the sintered NdFeB magnet 1, and the lower part is connected to the lower side wall of the sintered NdFeB magnet through the longitudinal injection molding layer 4.1; the top of the third protection member 5 is connected to the bottom surface of the sintered NdFeB magnet through the horizontal injection molding layer 4.2; the thickness of the injection molding layer 4 is 10 mm. The groove 7 is located at the connection between the two sides of the sintered NdFeB magnet 1 and the longitudinal injection layer 4.1. The sintered NdFeB magnet 1 is a cylindrical structure with a diameter of 12 cm and a height of 6.0 cm. Its volume is smaller than the volume of the protection part. The sintered NdFeB magnet is a cylindrical structure as a whole with a diameter of 20 cm and a height of 18 cm. The material of the protection part is copper.

[0038] In this embodiment, the functions of the various structures of a stable sintered NdFeB magnet assembly and the preparation method of the assembly are the same as those in Example 1.

[0039] Example 3

[0040] This embodiment provides a stable sintered NdFeB magnet assembly. Figure 1-3It is understood that it includes a sintered NdFeB magnet 1 and a protection part, the protection part includes a first protection member 2 and a second protection member 6 relatively arranged on the outside of the sintered NdFeB magnet 1, and a third protection member 5 arranged at the bottom of the sintered NdFeB magnet. The protection part surrounds the sintered NdFeB magnet 1 in a semi-enclosed shape. The first protection member 2 and the second protection member 6 have the same structure, and the top of the two is in the same horizontal plane as the top of the sintered NdFeB magnet 1. The side of the third protection member 5 is aligned with the side of the first protection member 2 and the second protection member 6. The first protection member 2, the second protection member 6 and the third protection member 5 are an integrated structure. A groove 7 is provided at three equal parts below the surface of the sintered NdFeB magnet 1. The groove 7 is an annular groove surrounding the sintered NdFeB magnet, with a height of 2.0 cm, a depth of 2.4 cm, a notch width of 1.0 cm, a groove bottom width less than the notch width, and a "U"-shaped cross section. The sintered NdFeB magnet 1 is connected to the protection part by injection molding, and an injection molding layer 4 is arranged between the two. The surface of the protection part is provided with two injection molding holes 3 connected to the injection molding layer 4. The injection molding hole 3 is set at a height of 12 cm, and its opening area is larger than the groove notch area. The injection molding layer 4 is composed of a longitudinal injection molding layer 4.1 surrounding the side wall of the sintered NdFeB magnet 1, a horizontal injection molding layer 4.2 located at the bottom of the longitudinal injection molding layer 4.1, an outer injection molding layer 4.3 connected to the injection molding hole 3, and an inner injection molding layer 4.4 connected to the groove 7. The upper part of the first protection member 2 and the second protection member 6 are in direct contact with the upper side wall of the sintered NdFeB magnet 1, and the lower part is connected to the lower side wall of the sintered NdFeB magnet through the longitudinal injection molding layer 4.1; the top of the third protection member 5 is connected to the bottom surface of the sintered NdFeB magnet through the horizontal injection molding layer 4.2; the thickness of the injection molding layer 4 is 5.0 mm. The groove 7 is located at the connection between the lower part of the sintered NdFeB magnet 1 and the longitudinal injection layer 4.1. The sintered NdFeB magnet 1 is a cylindrical structure with a diameter of 12 cm and a height of 6.0 cm. Its volume is smaller than the volume of the protection part. The sintered NdFeB magnet is a rectangular parallelepiped as a whole with a length of 20 cm, a width of 15 cm and a height of 18 cm. The material of the protection part is stainless steel.

[0041] In this embodiment, the functions of the various structures of a stable sintered NdFeB magnet assembly and the preparation method of the assembly are the same as those in Example 1.

[0042] Example 4

[0043] This embodiment provides a stable sintered NdFeB magnet assembly. Figure 1-3It is understood that it includes a sintered NdFeB magnet 1 and a protection part, the protection part includes a first protection member 2 and a second protection member 6 relatively arranged on the outside of the sintered NdFeB magnet 1, and a third protection member 5 arranged at the bottom of the sintered NdFeB magnet. The protection part surrounds the sintered NdFeB magnet 1 in a semi-enclosed shape. The first protection member 2 and the second protection member 6 have the same structure, and the top of the two is in the same horizontal plane as the top of the sintered NdFeB magnet 1. The side of the third protection member 5 is aligned with the side of the first protection member 2 and the second protection member 6. The first protection member 2, the second protection member 6 and the third protection member 5 are three separate parts. A groove 7 is provided at the center of the surface of the sintered NdFeB magnet 1. The groove 7 is an annular groove surrounding the sintered NdFeB magnet, with a height of 3.0 cm, a depth of 1.6 cm, a notch width of 1.1 cm, a groove bottom width less than the notch width, and a "U"-shaped cross section. The sintered NdFeB magnet 1 is connected to the protection part by injection molding, and an injection molding layer 4 is arranged between the two. The surface of the protection part is provided with two injection molding holes 3 connected to the injection molding layer 4. The injection molding hole 3 is set at a height of 12 cm, and its opening area is equal to the groove notch area. The injection molding layer 4 is composed of a longitudinal injection molding layer 4.1 surrounding the side wall of the sintered NdFeB magnet 1, a horizontal injection molding layer 4.2 located at the bottom of the longitudinal injection molding layer 4.1, an outer injection molding layer 4.3 connected to the injection molding hole 3, and an inner injection molding layer 4.4 connected to the groove 7. The upper part of the first protection member 2 and the second protection member 6 are in direct contact with the upper side wall of the sintered NdFeB magnet 1, and the lower part is connected to the lower side wall of the sintered NdFeB magnet through the longitudinal injection molding layer 4.1; the top of the third protection member 5 is connected to the bottom surface of the sintered NdFeB magnet through the horizontal injection molding layer 4.2; the thickness of the injection molding layer 4 is 15 mm. The groove 7 is located at the junction of the middle part of the sintered NdFeB magnet 1 and the longitudinal injection layer 4.1. The sintered NdFeB magnet 1 is a cylindrical structure with a diameter of 12 cm and a height of 6.0 cm. Its volume is smaller than the volume of the protection part. The sintered NdFeB magnet is a rectangular parallelepiped as a whole with a length of 20 cm, a width of 15 cm and a height of 18 cm. The material of the protection part is copper.

[0044] In this embodiment, the functions of the various structures of a stable sintered NdFeB magnet assembly and the preparation method of the assembly are the same as those in Example 1.

[0045] Example 5

[0046] This embodiment provides a stable sintered NdFeB magnet assembly. Figure 1-3It is understood that it includes a sintered NdFeB magnet 1 and a protection part, the protection part includes a first protection member 2 and a second protection member 6 relatively arranged on the outside of the sintered NdFeB magnet 1, and a third protection member 5 arranged at the bottom of the sintered NdFeB magnet. The protection part surrounds the sintered NdFeB magnet 1 in a semi-enclosed shape. The first protection member 2 and the second protection member 6 have the same structure, and the top of the two is in the same horizontal plane as the top of the sintered NdFeB magnet 1. The side of the third protection member 5 is aligned with the side of the first protection member 2 and the second protection member 6. The first protection member 2, the second protection member 6 and the third protection member 5 are an integrated structure. A groove 7 is provided at the center of the surface of the sintered NdFeB magnet 1. The groove 7 is an annular groove surrounding the sintered NdFeB magnet, and its height is 3.0 cm, the depth is 2.0 cm, the width of the notch is 1.5 cm, the width of the groove bottom is less than the width of the notch, and the cross section is an arc shape. The sintered NdFeB magnet 1 is connected to the protection part by injection molding, and an injection molding layer 4 is arranged between the two. An injection molding hole 3 connected to the injection molding layer 4 is arranged on the surface of the protection part. The injection molding hole 3 is set at a height of 12 cm, and its opening area is larger than the groove notch area. The injection molding layer 4 is composed of a longitudinal injection molding layer 4.1 surrounding the side wall of the sintered NdFeB magnet 1, a horizontal injection molding layer 4.2 located at the bottom of the longitudinal injection molding layer 4.1, an outer injection molding layer 4.3 connected to the injection molding hole 3, and an inner injection molding layer 4.4 connected to the groove 7. The upper part of the first protection member 2 and the second protection member 6 are in direct contact with the upper side wall of the sintered NdFeB magnet 1, and the lower part is connected to the lower side wall of the sintered NdFeB magnet through the longitudinal injection molding layer 4.1; the top of the third protection member 5 is connected to the bottom surface of the sintered NdFeB magnet through the horizontal injection molding layer 4.2; the thickness of the injection molding layer 4 is 15 mm. The groove 7 is located at the connection between the middle of the sintered NdFeB magnet 1 and the longitudinal injection layer 4.1. The sintered NdFeB magnet 1 is a cylindrical structure with a diameter of 12 cm and a height of 6 cm. Its volume is smaller than the volume of the protection part. The sintered NdFeB magnet is a rectangular parallelepiped as a whole with a length of 20 cm, a width of 15 cm and a height of 18 cm. The material of the protection part is stainless steel.

[0047] In this embodiment, the functions of the various structures of a stable sintered NdFeB magnet assembly and the preparation method of the assembly are the same as those in Example 1.

[0048] The above description is only a preferred embodiment of the present invention and does not constitute any limitation to the present invention. Any simple modification, change and equivalent structural transformation made to the above embodiments according to the technical essence of the present invention shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A stable sintered NdFeB magnet assembly, characterized in that: The invention comprises a sintered NdFeB magnet (1) and a protection part, wherein the protection part comprises a first protection member (2) and a second protection member (6) arranged on two sides of the sintered NdFeB magnet (1) relative to each other, and a third protection member (5) arranged at the bottom of the first protection member (2) and the second protection member (6), an injection molding layer (4) is arranged between the sintered NdFeB magnet (1) and the protection part, at least one injection molding hole (3) connected to the injection molding layer (4) is arranged on the surface of the protection part, and at least one groove (7) is arranged on the sintered NdFeB magnet (1) at a connection with the injection molding layer (4).

2. A stable sintered NdFeB magnet assembly according to claim 1, characterized in that: The groove (7) is a through hole horizontally penetrating the side of the sintered NdFeB magnet (1) or an annular groove surrounding the sintered NdFeB magnet (1), and the groove (7) has a notch width not less than the groove bottom width.

3. A stable sintered NdFeB magnet assembly according to claim 2, characterized in that: The depth of the groove (7) is less than 1 / 4 of the diameter of the sintered NdFeB magnet (1), and the width of the notch is not greater than 1 / 4 of the height of the sintered NdFeB magnet (1).

4. A stable sintered NdFeB magnet assembly according to claim 2, characterized in that: The groove (7) is arranged between the height center position and the lower third position of the sintered NdFeB magnet (1).

5. A stable sintered NdFeB magnet assembly according to any one of claims 2 to 4, characterized in that: The cross section of the groove (7) is a "U"-shaped or arc-shaped structure.

6. A stable sintered NdFeB magnet assembly according to claim 1, characterized in that: The injection molding layer (4) is composed of a longitudinal injection molding layer (4.1) surrounding the side wall of the sintered NdFeB magnet (1), a horizontal injection molding layer (4.2) located at the bottom surface of the longitudinal injection molding layer (4.1), an outer injection molding layer (4.3) connected to the injection molding hole (3), and an inner injection molding layer (4.4) connected to the groove (7); the thickness of the injection molding layer (4) is not less than 5.0 mm.

7. A stable sintered NdFeB magnet assembly according to claim 1, characterized in that: The sintered NdFeB magnet (1) has a symmetrical structure; the first protective member (2) and the second protective member (6) have the same structure and are symmetrically arranged on both sides of the sintered NdFeB magnet (1), and the tops of the three are in the same plane; the third protective member (5) is symmetrical along the central axis of the sintered NdFeB magnet (1); and the side surfaces of the protective members are flush.

8. A stable sintered NdFeB magnet assembly according to claim 7, characterized in that: The volume of the sintered NdFeB magnet (1) is smaller than the volume of the protection part.

9. A stable sintered NdFeB magnet assembly according to claim 6, characterized in that: The upper parts of the first protective member (2) and the second protective member (6) are in direct contact with the upper side wall of the sintered NdFeB magnet (1), and the lower parts are connected to the lower side wall of the sintered NdFeB magnet (1) via a longitudinal injection molding layer (4.1); the top of the third protective member (5) is connected to the bottom surface of the sintered NdFeB magnet (1) via a horizontal injection molding layer (4.2).

10. A stable sintered NdFeB magnet assembly according to claim 1, characterized in that: The protection part is made of non-magnetic metal.

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