Permanent magnet with insulation layer and preparation method and application thereof

Abstract

The application discloses a permanent magnet with an insulation layer and a preparation method and application thereof, the permanent magnet is provided with a separation groove, the groove of the separation groove is filled with an insulation layer, and the insulation layer can be a glue layer, an expansion coating, an injection agent or the like insulation material. According to the reasonable regulation and control of the three-dimensional direction size and filling rate of the separation groove, different strength permanent magnets can be accurately obtained according to target requirements, so that the permanent magnets are suitable for different application scenarios and cost can be saved. Meanwhile, the vacuum pressing process is adopted to fill the insulation layer in the separation groove of the permanent magnet, so that the permanent magnet with different shapes, widths and depths of the separation groove can be suitable, the filling rate of the insulation layer (such as glue) in the separation groove of the permanent magnet is high, so that the mechanical performance of the permanent magnet is guaranteed; meanwhile, the flatness of the insulation layer after filling of the separation groove and the surface of the permanent magnet can be improved after vacuum treatment, and the overall corrosion resistance of the product is further improved.

Description

Technical Field

[0001] This invention belongs to the field of rare earth permanent magnet preparation technology, and relates to a permanent magnet with an insulating layer, its preparation method and application, specifically a rare earth permanent magnet with high strength and excellent corrosion resistance with an insulating layer, its preparation method and application. Background Technology

[0002] Neodymium iron boron permanent magnets are widely used in energy-saving and environmental protection and new energy fields such as new energy vehicles, wind power generation, energy-saving elevators, and energy-saving home appliances due to their excellent performance. With the development of motor miniaturization, lightweighting and high speed, reducing the eddy current loss of rotor permanent magnets while ensuring the mechanical properties and corrosion resistance of permanent magnets is an important issue in the industry.

[0003] Currently, there are two main methods to reduce eddy current losses in permanent magnets: one is to bond magnets together, which involves placing an adhesive layer between magnets to form a magnetic assembly. This method is costly, has a long processing time, and requires precise positioning of the magnets before bonding, as well as strict requirements on the bonding process, such as the method and uniformity of adhesive application. The other method is to create a separator groove to increase the resistivity of the permanent magnet itself, but this cannot guarantee the insulation between the magnets on both sides of the separator groove, and it also reduces the mechanical strength of the permanent magnet. To solve these technical problems, some researchers have proposed filling the separator groove with insulating material. However, due to the narrow gaps in the separator groove, the filling process is complex, and the filling strength is low, so the mechanical properties of the permanent magnet still cannot be guaranteed.

[0004] Currently, reports on permanent magnet separators mainly focus on the shape of the separator, while there is no substantial discussion on the filling methods for different separator shapes and the processes that improve mechanical strength and corrosion resistance. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention provides a permanent magnet having partition grooves, the grooves of which are filled with an insulating layer. Preferably, the insulating layer can be an adhesive layer, an expanding coating, an injection molding agent, or other insulating materials; more preferably, it is an adhesive layer.

[0006] In this invention, the filling ratio P of the insulating layer at any cross-section within the partition groove (defined as the area of ​​the insulating layer filler divided by the cross-sectional area of ​​the partition groove) is denoted as P1 for the first partition groove, P2 for the second partition groove, and so on, with the filling ratio of the Nth partition groove denoted as P2. n Let P = (P1 + P2 + ... + P n P is the overall filling ratio of the insulation layer in each partition groove, specifically the average filling ratio of each partition layer.

[0007] According to an embodiment of the present invention, the filling ratio of the insulating layer in any partition groove satisfies: Pn ≥50%, preferably 80%-100%, for example 60%, 70%, 80%, 90%, 100%; and the overall filling ratio of the permanent magnet satisfies: P≥80%, preferably 90%-100%, for example 90%, 95%, 100%.

[0008] According to an embodiment of the present invention, the permanent magnet can be a conventional permanent magnet in the art, such as a neodymium iron boron magnet.

[0009] According to an embodiment of the present invention, the adhesive used in the adhesive layer is selected from one or more combinations of epoxy resin adhesive, acrylic resin adhesive, phenolic resin adhesive and unsaturated polyester resin adhesive, preferably epoxy resin adhesive.

[0010] According to an embodiment of the present invention, the viscosity of the adhesive is 1-5000 mPa·s, preferably 1-2000 mPa·s. When the viscosity of the adhesive is too high, its fluidity is poor, making it difficult to penetrate into the gaps of the partition groove, resulting in poor wetting properties and hindering the adhesion and bonding of the adhesive. When the viscosity of the adhesive is too low, its fluidity is good, but it makes it difficult for the adhesive to be maintained and positioned in the gaps of the partition groove, resulting in a low filling rate and consequently low mechanical strength of the permanent magnet.

[0011] According to an embodiment of the present invention, after filling the insulating layer, the flatness of all surfaces of the permanent magnet is ≤0.05mm. Preferably, the flatness is ≤0.03mm, for example, 0.15mm, 0.20mm, 0.25mm, or 0.30mm.

[0012] In this invention, flatness refers to the variation of the actual surface of the measured permanent magnet relative to its ideal plane (also known as flatness error). Flatness error is calculated by comparing the actual surface to the ideal plane, and the linear distance between the two is the flatness error value; or by measuring the relative height difference of several points on the actual surface and then converting it into a flatness error value expressed as a linear value.

[0013] According to an embodiment of the present invention, after filling the insulating layer, the neutral salt spray of the magnet is >240h, exemplarily 240h, 260h, 270h, 280h, 288h, 300h, 312h, and 320h.

[0014] According to an embodiment of the present invention, the dividing groove may or may not penetrate the permanent magnet in a first extending direction and may not penetrate the permanent magnet in a second extending direction, wherein the first extending direction of the dividing groove is parallel to the magnetization direction of the permanent magnet, or the first extending direction of the dividing groove forms an angle with the magnetization direction of the permanent magnet. The second extending direction of the dividing groove is parallel to the width or length direction of the permanent magnet, or the second extending direction of the dividing groove forms an angle with the width or length direction of the permanent magnet. For example, the angle is 0-90°, such as 10°, 20°, 30°, 40°, 50°, 60°, 70°, or 80°.

[0015] According to an embodiment of the present invention, the number of the dividing grooves can be one, two or more, denoted as N; wherein, the length in the first extending direction is denoted as L. 1-1 L 1-2 L 1-3 L 1-4 ...L 1-n Let L1 (mm) be the sum of the lengths of the dividing grooves in their first extending direction, then L1 = L 1-1 +L 1-2 +L 1-3 +L 1-4 +……+L 1-n L1 is 50% or more of the length of the permanent magnet in the first extension direction, preferably 60% or more, and exemplarily 50%, 60%, 70%, 80%, or 100%.

[0016] According to an embodiment of the present invention, the length of the dividing groove in its second extending direction is denoted as L. 2-1 L 2-2 L 2-3 L 2-4 ...L 2-n Let L2 (mm) be the sum of the lengths of the dividing grooves in their second extension direction, then L2 = L 2-1 +L 2-2 +L 2-3 +L 2-4 +……+L 2-n L2 is 30% or more, preferably less than 50%, of the length of the permanent magnet in the second extending direction. Preferably, the length L2 of the dividing groove in the second extending direction is 30% to 50% of the length of the permanent magnet in the second extending direction, for example, 40% or 50%.

[0017] According to an embodiment of the present invention, when the second extending direction of the dividing groove forms an angle with the width direction or length direction of the permanent magnet, the projected length of the dividing groove with the angle in the second extending direction is more than 30% of the length of the permanent magnet in the second extending direction, preferably less than 50%; preferably, the projected length of the dividing groove with the angle in the second extending direction is 30% to 50% of the length of the permanent magnet in the second extending direction, for example 40% and 50%.

[0018] According to an embodiment of the present invention, the width of the partition groove is denoted as W (mm), where W is 0.1mm-0.5mm, preferably 0.12-0.25mm, and the width refers to the distance between the two sidewalls within the partition groove.

[0019] According to an embodiment of the present invention, when there are multiple partition grooves, the distance between two adjacent partition grooves is 1-10mm, preferably 1-5mm, and exemplary values ​​are 1mm, 2mm, 5mm, 8mm, and 10mm.

[0020] According to an embodiment of the present invention, the distribution of the dividing grooves on the permanent magnet is either single-sided grooving (defined as having at least one dividing groove on one surface of the permanent magnet) or staggered grooving (defined as having at least one dividing groove on each of the two opposite surfaces of the permanent magnet), preferably staggered grooving.

[0021] According to an embodiment of the present invention, the surface of the partition groove in the first extending direction is denoted as a first side surface, a second side surface, a third side surface, or a fourth side surface; the surface of the partition groove in the second extending direction is denoted as a first surface or a second surface; wherein the perimeter of the first surface or the second surface is denoted as C; then 0.2≤L2 / C≤1; more preferably, 0.35≤L2 / C≤0.85.

[0022] When the ratio of the total length L2 to C in the second extension direction is small, the slot length is too short to significantly cut the magnetic field lines of the magnet, thus failing to reduce eddy current losses, and the magnet temperature rise remains large. When the ratio of the total length L2 to C in the second extension direction is large, the excessively large slot ratio will cause a decrease or unevenness in magnet strength, making the magnet prone to damage.

[0023] According to an embodiment of the present invention, the number of the dividing grooves on the first side surface, the second side surface, the third side surface, or the fourth side surface is N1, and the number of the dividing grooves on the first surface or the second surface is N2.

[0024] The inventors unexpectedly discovered that the length and method of slotting in the second extension direction have a significant impact on the final performance of the product.

[0025] The present invention also provides a method for preparing the above-mentioned permanent magnet, including preparing a partition groove on the permanent magnet, pre-treating it, filling the groove of the permanent magnet with an insulating layer, and curing the permanent magnet after filling with the insulating layer to obtain the permanent magnet.

[0026] According to an embodiment of the present invention, the method for preparing the permanent magnet includes the following steps:

[0027] (1) Magnet preparation: Prepare permanent magnets with partition grooves and then perform pretreatment;

[0028] (2) Glue filling: Apply glue to the gaps in the partition groove, then (place it in a vacuum-sealed container) and vacuum it to fill the partition groove with glue.

[0029] (3) Curing treatment: The permanent magnet filled with glue in the partition groove is cured to obtain the permanent magnet.

[0030] According to an embodiment of the present invention, the preparation method may further include step (4): surface treatment of the permanent magnet obtained above.

[0031] According to an embodiment of the present invention, in step (1), the pretreatment includes cleaning, degreasing, and drying the permanent magnet with the partition groove. Optionally, it includes at least one of the following treatments: phosphating, passivation, ceramicizing, silanizing, chelating, and blackening.

[0032] According to an embodiment of the present invention, in step (2), the glue can be applied by at least one of dispensing, manual application, spraying, or dipping; preferably, it can be applied by dispensing.

[0033] Preferably, the dispensing speed is 1-50 mm / s, with examples being 1 mm / s, 5 mm / s, 10 mm / s, 20 mm / s, 30 mm / s, 40 mm / s, 50 mm / s, and 50 mm / s; the nozzle diameter of the dispensing machine used is 0.16-0.26 mm, with examples being 0.16 mm, 0.18 mm, 0.20 mm, 0.22 mm, 0.24 mm, and 0.26 mm. When the dispensing speed is too slow, the work efficiency is low; while when the dispensing speed is too fast, it is not easy to place the glue in the gaps, and the glue is prone to overflow.

[0034] According to an embodiment of the present invention, in step (2), the method of applying (single-sided application) of adhesive to the gaps of the partition groove is as follows: at least the adhesive is applied to a portion of the partition groove in its second extension direction; preferably, one of the two opposing gaps of the partition groove in its second extension direction is applied; preferably, the application length L (mm) of the adhesive is not less than half of the extension length L2 (mm) of the partition groove in its second extension direction, i.e., L≥50%*L2, preferably the application length L (mm) of the adhesive is 70%-90% of the extension length L2 (mm) of the partition groove in its second extension direction, for example 70%, 80%, 90%.

[0035] According to an embodiment of the present invention, in step (2), the amount of adhesive added depends on the volume of the dividing groove, and the filling rate depends on the weight before and after filling and the uniformity of the adhesive layer distribution on the cut surface. Preferably, the filling ratio P of the adhesive is ≥ 50%, more preferably 80%-100%, for example 50%, 60%, 70%, 80%, 90%, 100%.

[0036] According to an embodiment of the present invention, in step (2), the vacuuming can be performed using a hermetically sealable vacuum device known in the art. For example, the vacuum pressure is -1.0 bar to 1 mbar, and the vacuum pressure is maintained for ≥1 s. If the vacuum pressure is less than -1.0 bar or greater than 1 mbar, a good filling effect cannot be achieved.

[0037] According to an exemplary embodiment of the present invention, in step (2), the vacuum pressure is -0.8 bar to 0.5 m bar, and the vacuum pressure is maintained for ≥3 s.

[0038] According to an embodiment of the present invention, in step (2), before the vacuuming is performed, a thin film can be covered on the surface of the permanent magnet coated with adhesive. The film applies downward pressure to the adhesive layer during the pressing process, causing the adhesive to quickly enter the dividing groove. Simultaneously, the film reduces the vacuum level in the dividing groove gaps to ensure sufficient adhesive filling, thereby helping to increase the filling ratio of the insulating layer within the dividing groove. Preferably, the film is made of semi-rigid plastic, and its material is not limited; it can adhere fully or partially to the surface of the permanent magnet after being subjected to force. Preferably, the thickness of the film is 0.01mm-0.5mm. Exemplarily, the film can be made of polyethylene, polyvinyl chloride, polypropylene, polyester, or nylon. In this invention, if the film is too thick, it will waste resources; while if the film is too thin, it is easily scratched by the edges of the magnet during vacuuming, thus failing to achieve a sealing effect and easily being sucked into the gaps by the vacuum, which will reduce the flatness of the slotted magnet containing the insulating layer.

[0039] According to an embodiment of the present invention, the coverage area of ​​the film is not less than the area of ​​the adhesive coating on one of the two opposing slits of the partition groove in its second extension direction and / or the coverage area of ​​the film is not less than the area of ​​the first surface or the second surface of the permanent magnet.

[0040] According to an embodiment of the present invention, in step (2), a support component for placing a permanent magnet coated with adhesive is placed inside the sealable vacuum-ejecting device. Preferably, the number of contact points between the support component and the permanent magnet is at least two, for example, two, three, or more. Preferably, the support component does not contact any of the gaps in the partition groove. The present invention does not impose any particular limitations on the structure of the support component, as long as it can provide stable support and prevent one side of the permanent magnet from contacting the inner wall of the container.

[0041] The inventors unexpectedly discovered that during the pressing process, the single-sided film applied downward pressure to the coated adhesive layer, allowing the adhesive to quickly enter the dividing grooves. The suspended support component prevented one side of the permanent magnet from contacting the inner wall of the container, allowing the adhesive to more fully fill the dividing grooves of the permanent magnet, thereby increasing the filling rate and thus improving the bending strength of the permanent magnet.

[0042] According to an embodiment of the present invention, the glue filling can be done once or multiple times.

[0043] According to an embodiment of the present invention, in step (3), the curing temperature is 20℃-200℃, preferably 50℃-150℃, and examples are 20℃, 50℃, 80℃, 100℃, 150℃, and 200℃; the curing time is 0.5-8h, preferably 1-3h, and examples are 0.5h, 1h, 2h, 3h, 5h, and 8h.

[0044] According to an embodiment of the present invention, in step (4), the post-treatment includes at least one of phosphating and spraying. Through post-treatment, not only is the corrosion resistance of the permanent magnet surface further improved, serving as the final protective layer for the permanent magnet, but the magnetic properties of the magnet are not affected.

[0045] The present invention also provides the application of the above-mentioned permanent magnet in the field of motors.

[0046] The present invention also provides an electric motor having a rotor, the rotor including the aforementioned permanent magnet.

[0047] Compared with the prior art, the beneficial effects of the present invention are:

[0048] 1. This invention improves the bending strength of permanent magnets and reduces the eddy current effect of permanent magnets by filling the partition grooves with an insulating layer, thereby improving the performance of the motor after installation.

[0049] 2. This invention uses a vacuum pressing process to fill the insulating layer in the partition groove of the permanent magnet, so it is applicable to permanent magnets with partition grooves of different shapes, widths and depths. The insulation layer (such as glue) in the partition groove of the permanent magnet of this invention has a high filling rate, thereby ensuring the mechanical properties of the permanent magnet; at the same time, vacuum treatment can also improve the flatness of the insulating layer and the surface of the permanent magnet after the partition groove is filled, thereby improving the overall corrosion resistance of the product.

[0050] 3. By rationally controlling the three-dimensional dimensions and filling rate of the partition groove, this invention can accurately obtain permanent magnets of different strengths according to target requirements, making them suitable for different application scenarios and saving costs. Attached Figure Description

[0051] Figure 1 (a) is a schematic diagram of the first and / or second surfaces of the partition groove in Example 1; Figure 1 (b) is a schematic diagram of the first and / or second side surfaces of the partition groove in Example 1. Figure 1 (c) is a schematic diagram of the third side surface of the cutting method of the partition groove in Example 1.

[0052] Figure 2 (a) is a schematic diagram of the first and / or second surfaces of the partition groove in Example 2. Figure 2 (b) is a schematic diagram of the first and / or second side surfaces of the partition groove in Example 2. Figure 2 (c) is a schematic diagram of the third side surface of the cutting method of the partition groove in Example 2.

[0053] Figure 3 (a) is a schematic diagram of the first and / or second surfaces of the partition groove in Example 3; Figure 3 (b) is a schematic diagram of the first and / or second side surfaces of the partition groove in Example 3; Figure 3 (c) is a schematic diagram of the third side surface of the cutting method of the partition groove in Example 3.

[0054] Figure 4 (a) is a schematic diagram of the first and / or second surfaces of the partition groove in Example 4; Figure 4 (b) is a schematic diagram of the first and / or second side surfaces of the partition groove in Example 4; Figure 4 (c) is a schematic diagram of the third side surface of the cutting method of the partition groove in Example 4.

[0055] Figure 5 (a) is a schematic diagram of the first and / or second surfaces of the partition groove in Example 5. Figure 5(b) is a schematic diagram of the first and / or second side surfaces of the partition groove in Example 5; Figure 5 (c) is a schematic diagram of the third side surface of the cutting method of the partition groove in Example 5.

[0056] Figure 6 (a) is a schematic diagram of the first and / or second surfaces of the partition groove in Example 6; Figure 6 (b) is a schematic diagram of the first and / or second side surfaces of the partition groove in Example 6; Figure 6 (c) is a schematic diagram of the third side surface of the cutting method of the partition groove in Example 6.

[0057] Figure 7 (a) is a schematic diagram of the first and / or second surfaces of the partition groove in Example 7; Figure 7 (b) is a schematic diagram of the first and / or second side surfaces of the partition groove in Example 1. Figure 7 (c) is a schematic diagram of the third side surface of the cutting method of the partition groove in Example 7.

[0058] Figure 8 (a) is a schematic diagram of the first and / or second surfaces of the partition groove in Example 8; Figure 8 (b1, b2) are schematic diagrams of the first and / or second side surfaces of the partition groove cutting method in Example 8; Figure 8 (c) is a schematic diagram of the third side surface of the cutting method of the partition groove in Example 8.

[0059] Figure 9 (a) is a schematic diagram of the first and / or second surfaces of the partition groove in Example 9; Figure 9 (b) is a schematic diagram of the first and / or second side surfaces of the partition groove in Example 9; Figure 9 (c) is a schematic diagram of the third side surface of the cutting method of the partition groove in Example 9.

[0060] Figure 10 This is a schematic diagram of the permanent magnet with partitioned grooves used in Example 13.

[0061] Figure 11 This is a front view of the large surface after the partition groove of Example 1 has been filled.

[0062] Figure 12 This is a photograph of the actual object after the dividing groove of Example 1 was filled and then broken off from the glue. Detailed Implementation

[0063] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0064] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0065] Test method:

[0066] The permanent magnets prepared according to the following embodiments and comparative examples of the present invention were tested for bending strength, neutral salt spray performance, and glue filling rate, using the following methods:

[0067] 1) Bending strength: Using an electronic universal testing machine, a three-point bending test was conducted in accordance with standard YB / T5349-2014, and the test was performed three times.

[0068] 2) Adhesive filling ratio P: On the first surface of the magnet, the permanent magnet is cut perpendicular to the second dividing direction of the dividing groove to obtain the cross-section of the dividing groove. The cutting method is as follows: Figure 8 The cut surfaces were observed under a scanning electron microscope and examined using a field emission electron probe microanalysis (FE-EPMA) system (JEOL, 8530F). The area percentage was analyzed using Image-ProPlus software.

[0069] 3) Neutral salt spray performance (SST test): Tested according to GB / T 10125-2012.

[0070] 4) Flatness: Tested using a pointer-type dial indicator.

[0071] Examples 1-9

[0072] A method for preparing a permanent magnet includes the following steps:

[0073] (1) Magnet preparation:

[0074] A permanent magnet with a size of 40mm×12mm×4mm was prepared using a method known in the art. The permanent magnet used in Examples 1-9 and Comparative Examples 1-8 was grade 45UH.

[0075] The permanent magnets in Examples 1-9 are machined with dividing grooves using multi-wire cutting. The width of the dividing grooves in Examples 1-5 is 0.12 mm, and the width of the dividing grooves in Examples 6-9 is 0.2 mm. The lengths and number of divisions in the first and second extension directions are shown in Tables 1 and 2. The division method of the dividing grooves in the permanent magnets of Examples 1-9 is as follows: Figure 1-9 As shown.

[0076] Table 1

[0077]

[0078] Table 2

[0079]

[0080]

[0081] (2) Glue filling:

[0082] Using a dispensing machine, epoxy adhesive (F-44 type phenolic epoxy resin) is applied to the gaps of each dividing groove on the first surface of the permanent magnet obtained in the above steps. The length of the adhesive application is equal to the length of the dividing groove in the second extension direction, i.e., L = L2; the dispensing speed is 35 mm / s, and the diameter of the dispensing machine nozzle is 0.20 mm.

[0083] The slotted permanent magnet containing glue filler is placed on the support component, with contact points between the slotted permanent magnet and the support component. It is then placed into a polyethylene film sealing bag (size 80mm*40mm) with a thickness of 0.03mm, and then placed in a sealed container for vacuum treatment.

[0084] The specific glue length, number of support points, vacuuming pressure time, and number of glue filling times are shown in Table 3.

[0085] Table 3

[0086] Example 1 6 2 -0.5bar*5s 2 Example 2 6 3 -0.5bar*5s 1 Example 3 5 4 -0.5bar*5s 2 Example 4 5 1 -0.5bar*5s 3 Example 5 3 2 -1bar*8s 3 Example 6 6 3 -1 bar * 10 s 1 Example 7 2 4 0.5 bar * 3 seconds 3 Example 8 4 1 1 bar * 6 seconds 2 Example 9 15 1 1 bar * 6 seconds 4

[0087] (3) Curing treatment:

[0088] For permanent magnets filled with adhesive in the partition groove, the curing conditions are: curing at 150℃ for 3 hours, and then cooling to room temperature.

[0089] (4) Surface treatment:

[0090] A permanent magnet with an insulating layer was placed in Ailsm's BW-231 zinc-based phosphating solution (zinc dihydrogen phosphate 100g / L, phosphoric acid 200g / L, tannic acid 15g / L, calcium nitrate 10g / L, ammonium molybdate 20g / L, phytic acid 50g / L, film-forming agent 30g / L, the remainder being water. The phosphating solution was mixed with pure water at a volume ratio of 3:1) for phosphating treatment at 50℃ for 2 minutes. Then, a 20μm thick epoxy resin coating was sprayed onto the permanent magnet to obtain a permanent magnet with an insulating layer.

[0091] Example 10

[0092] A method for preparing a permanent magnet differs from Example 1 in that: Step (2) glue filling: A dispensing machine is used with a dispensing speed of 45 mm / s and a nozzle diameter of 0.26 mm. The slotted permanent magnet containing glue filler is placed into a polyethylene film sealed bag (90 mm * 40 mm) with a thickness of 0.1 mm, placed in a sealed container, and subjected to vacuum treatment. The vacuum pressure is 0.5 bar and the maintenance time is 5 s.

[0093] Example 11

[0094] A method for preparing a permanent magnet, compared with Example 2, differs in that: Step (2) glue filling: a dispensing machine is used with a dispensing speed of 20 mm / s and a nozzle diameter of 0.16 mm. The slotted magnet containing glue filler is placed on a support component, with one contact point between the slotted magnet and the support component. It is then placed in a polyethylene film sealed bag (50 mm * 30 mm) with a thickness of 0.2 mm, placed in a sealed container, and subjected to vacuum treatment. The vacuum pressure is 0.2 bar and the maintenance time is 10 s.

[0095] Example 12

[0096] A method for preparing a permanent magnet, compared with Example 2, differs in that: Step (2) glue filling: a dispensing machine is used with a dispensing speed of 15 mm / s and a nozzle diameter of 0.22 mm. The slotted magnet containing glue filler is placed on a support component, with two contact points between the slotted magnet and the support component. A polyethylene film with a thickness of 0.1 mm is used to cover the first surface of the slotted magnet, which can fully cover the first surface and cover 300% of the area of ​​the first surface (size 120 mm * 36 mm). It is then placed in a sealed container and subjected to vacuum treatment with a vacuum pressure of 0.5 bar and a holding time of 2 seconds.

[0097] Example 13

[0098] A method for preparing a permanent magnet, which differs from Example 1 in that: Step (1) Magnet preparation: The permanent magnet is processed with a multi-wire cutting method to create a partition groove, wherein the width of the partition groove is 0.18 mm. Furthermore, the second extending direction forms a 30° angle with the sidewall extending direction, see... Figure 10 .

[0099] The bending strength of the permanent magnets prepared in Examples 1-13 and the glue filling ratio P of the smallest partition groove among all partition grooves were tested. n The average filling ratio P of all partitioned slots, flatness, and neutral salt spray performance are shown in Table 4.

[0100] Table 4

[0101]

[0102] Comparative Example 1

[0103] A method for preparing a permanent magnet differs from Example 2 in that the glue filling length in step (2) is 5 mm.

[0104] Comparative Example 2

[0105] A method for preparing a permanent magnet differs from Example 2 in that the glue filling length in step (2) is 4 mm.

[0106] Comparative Example 3

[0107] A method for preparing a permanent magnet, which differs from Example 2 in that: step (2) glue filling is: the slotted permanent magnet containing glue filler is placed on the support component, the slotted permanent magnet has a contact point with the support component, and then placed in a polyethylene film sealed bag (size 60mm*40mm) with a thickness of 0.03mm, and placed in a sealed container and left to stand naturally for 10 minutes.

[0108] Comparative Example 4

[0109] A method for preparing a permanent magnet differs from Example 2 in that: step (2) glue filling is: the slotted permanent magnet containing glue filler is placed into a polyethylene film sealed bag (size 60mm*40mm) with a thickness of 0.03mm, placed in a sealed container, and vacuumed.

[0110] Comparative Example 5

[0111] A method for preparing a permanent magnet, which differs from Example 1 in that: Step (2) glue filling: The slotted permanent magnet containing glue filler is placed on the support component, and there are 2 contact points between the slotted permanent magnet and the support component. It is placed in a sealed container and vacuumed. The vacuum pressure is -0.5 bar and the holding time is 9 s.

[0112] Comparative Example 6

[0113] A method for preparing a permanent magnet, which differs from Example 1 in that: Step (2) glue filling: The slotted permanent magnet containing glue filler is placed on the support component, the slotted permanent magnet has a contact point with the support component, and then placed into a polyethylene film sealed bag (size 35mm*10mm) with a thickness of 0.03mm, and then placed in a sealed container for vacuum treatment.

[0114] Comparative Example 7

[0115] A method for preparing a permanent magnet, which differs from Example 1 in that: Step (2) glue filling: The slotted magnet containing glue filler is placed on the support component, and there are 2 contact points between the slotted permanent magnet and the support component. Then it is placed in a polyethylene film sealed bag with a thickness of 0.03mm, placed in a sealed container, and vacuum treatment is performed. The vacuum pressure is 2 bar and the maintenance time is 6s.

[0116] The bending strength, glue filling ratio, flatness, and neutral salt spray performance of the permanent magnets prepared in Comparative Examples 1-7 were tested, and the results are shown in Table 4 below.

[0117] Table 4

[0118]

[0119] A comparison of the results of Examples 1-13 and Comparative Examples 1-7 shows that, by using different cutting methods to divide and groove the permanent magnets before filling them with an insulating layer, the present invention significantly improves the bending strength and neutral salt spray time of the permanent magnets obtained in Examples 1-13. However, in Comparative Examples 1 and 2, the average filling ratio of the divided layer is lower because the coating length L (mm) of the adhesive and the extension length L2 (mm) of the dividing groove in its second extension direction do not satisfy L≥50%*L2, resulting in poor bending strength and neutral salt spray time performance of the obtained permanent magnets. In Comparative Examples 3, 6, and 7, although the filling ratio of the permanent magnets is increased, the flatness of the permanent magnets is poor, and the bending strength and neutral salt spray (corrosion resistance) performance of the magnets are also reduced. Comparative Example 8 uses excessive vacuum treatment. Due to the excessive vacuum pressure, the vacuum condition is achieved instantaneously before the adhesive is evenly distributed, which is not conducive to the uniform distribution of the adhesive, thus reducing the flatness and bending strength of the permanent magnets.

[0120] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A permanent magnet, characterized by The permanent magnet is provided with a partition groove, and the groove of the partition groove is filled with an insulating layer; The insulation layer filling ratio within any partition groove is 80%-100%; The dividing groove may or may not penetrate the permanent magnet in the first extension direction of the dividing groove, and does not penetrate the permanent magnet in the second extension direction of the dividing groove; The first extending direction of the partition groove is parallel to the magnetization direction of the permanent magnet, or the first extending direction of the partition groove has an angle with the magnetization direction of the permanent magnet; The second extending direction of the partition groove forms an angle with the width or length direction of the permanent magnet, and the angle is 10°-80°. The sum of the lengths of the dividing grooves in their second extension direction is denoted as L2, the surface of the dividing grooves in the second extension direction is denoted as the first surface or the second surface, and the perimeter of the first surface or the second surface is denoted as C; then 0.35≤L2 / C≤0.85; When the second extending direction of the partition groove forms an angle with the width or length direction of the permanent magnet, the projected length of the partition groove with the angle in the second extending direction is more than 30% and less than 50% of the length of the permanent magnet in the second extending direction.

2. The permanent magnet as described in claim 1, characterized in that, The insulating layer is an adhesive layer, an expanding coating, or an injection molding agent.

3. The permanent magnet as described in claim 2, characterized in that, The adhesive used in the adhesive layer is selected from one or more combinations of epoxy resin adhesive, acrylic resin adhesive, phenolic resin adhesive and unsaturated polyester resin adhesive. The viscosity of the adhesive is 1-5000 mPa·s.

4. The permanent magnet as described in any one of claims 1-3, characterized in that, After the insulating layer is filled, the flatness of all surfaces of the permanent magnet is ≤0.05mm.

5. The permanent magnet according to any one of claims 1-3, characterized in that, After the insulating layer is filled, the neutral salt spray of the magnet lasts for >240h.

6. The permanent magnet according to any one of claims 1-3, characterized in that, The width of the dividing groove is denoted as W, where W is 0.1mm-0.5mm.

7. The permanent magnet according to any one of claims 1-3, characterized in that, When there are multiple partition slots, the distance between two adjacent partition slots is 1-10mm.

8. The permanent magnet according to any one of claims 1-3, characterized in that, The dividing grooves on the permanent magnet are distributed in a single-sided groove or staggered groove pattern.

9. A method for preparing a permanent magnet according to any one of claims 1-8, characterized in that, The preparation method includes preparing a partition groove on a permanent magnet, pre-treating it, filling the groove of the permanent magnet with an insulating layer, and then curing the permanent magnet after filling with the insulating layer to obtain the permanent magnet.

10. The method for preparing a permanent magnet as described in claim 9, characterized in that, Includes the following steps: (1) Magnet preparation: Prepare permanent magnets with partition grooves and then perform pretreatment; (2) Glue filling: Apply glue to the gaps of the partition groove, then vacuum to fill the partition groove with glue; (3) Curing treatment: The permanent magnet filled with glue in the partition groove is cured to obtain the permanent magnet.

11. The method for preparing a permanent magnet as described in claim 10, characterized in that, The preparation method further includes step (4): surface treatment of the permanent magnet obtained above.

12. The method for preparing a permanent magnet as described in claim 10, characterized in that, In step (1), the pretreatment includes cleaning, degreasing and drying the permanent magnet with the partition groove.

13. The method for preparing a permanent magnet as described in claim 10, characterized in that, In step (2), the glue is applied by at least one of the following methods: dispensing, manual application, spraying, or dipping.

14. The method for preparing a permanent magnet as described in claim 13, characterized in that, The dispensing speed is 1-50 mm / s; the diameter of the dispensing gun head used in the dispensing process is 0.16-0.26 mm.

15. The method for preparing a permanent magnet as described in claim 10, characterized in that, In step (2), the method of applying glue to the gap of the partition groove is to apply glue to at least a portion of the partition groove in its second extension direction.

16. The method for preparing a permanent magnet as described in claim 15, characterized in that, The coating is applied to one of the two opposing slits in the second extension direction of the dividing groove. The coating length L of the adhesive is not less than half of the extension length l2 of the separator groove in its second extension direction, i.e., L≥50%*l2.

17. The method for preparing a permanent magnet as described in claim 16, characterized in that, The coating length L of the adhesive is 70%-90% of the extension length l2 of the separator groove in its second extension direction.

18. The method for preparing a permanent magnet as described in claim 10, characterized in that, In step (2), the glue filling ratio is 80%-100%.

19. The method for preparing a permanent magnet as described in claim 10, characterized in that, In step (2), the vacuum pressure is -1.0 bar to 1 m bar, and the vacuum pressure is maintained for ≥1 s.

20. The method for preparing a permanent magnet as described in claim 10, characterized in that, In step (2), before the vacuuming is performed, a thin film is covered on the surface of the permanent magnet coated with glue, and the thickness of the film is 0.01mm-0.5mm.

21. The method for preparing a permanent magnet as described in claim 10, characterized in that, In step (3), the curing temperature is 20℃-200℃; the curing time is 0.5-8h.

22. The application of the permanent magnet according to any one of claims 1-8 or the permanent magnet prepared by the preparation method according to any one of claims 9-21 in the field of motors.

23. An electric motor having a rotor, the rotor comprising a permanent magnet as described in any one of claims 1-8 or a permanent magnet prepared by the preparation method described in any one of claims 9-21.

Images