Grooved magnetic steel and method for manufacturing the same

Abstract

The application provides a slotted magnetic steel and a preparation method thereof. The upper and lower surfaces of the slotted magnetic steel are provided with a plurality of through grooves along the direction of the orientation of the magnet. The tail end of the cross section of the through groove along the direction of the orientation of the magnet is in a circular arc shape. A machine filler is arranged in the through groove. The slotted magnetic steel has excellent effects in terms of magnetic performance and mechanical performance, and has low preparation cost.

Description

TECHNICAL FIELD

[0001] The present application relates to a slotted magnetic steel and a preparation method thereof. BACKGROUND

[0002] Nd-Fe-B is the largest magnetic material in terms of magnetic energy product, and can provide the largest magnetic field in the same volume among similar materials, so it is widely used in new energy vehicles, wind power, energy-saving motors and other fields in today's energy-saving production era.

[0003] When a conductor moves in a non-uniform magnetic field or is in a time-varying magnetic field, an induced current will be generated in the conductor. This current forms a closed current line in the conductor, which is called eddy current (also known as Foucault current). The magnetic steel is generally bonded or inlaid on the rotor body, and is affected by the alternating current of the motor stator. The magnetic body itself generates induced eddy current, which causes the magnetic body to heat up quickly, and when the temperature exceeds the working temperature, the magnetic body is easily demagnetized. At the same time, the eddy current reduces the working efficiency of the motor and increases the energy consumption. Therefore, controlling the temperature rise of the magnetic body during motor operation can significantly improve the performance and reliability of the motor.

[0004] The method for reducing the eddy current effect of the magnetic steel in the prior art can be used to process the steel body of the magnetic steel, for example, a magnetic steel is stacked on the original single magnetic steel to form a double-layer structure, and an insulating material is used in the upper and lower magnetic steels. Although this method can reduce the eddy current effect of the magnetic steel to some extent, the production cost is high, which is not conducive to mass production of products. SUMMARY

[0005] The present application provides a slotted magnetic steel and a preparation method thereof. The slotted magnetic steel has excellent magnetic and mechanical properties, and the preparation cost is low.

[0006] The present application solves the above technical problems by the following technical solutions.

[0007] The present application provides a slotted magnetic steel, which has a plurality of through grooves on the upper and lower surfaces along the direction parallel to the orientation direction of the magnetic body. The tail end of the cross section of the through groove is in a circular arc shape, and the through groove is provided with a filler.

[0008] In the present application, the tail end of the cross section of the through groove is set to be a circular arc shape, which is not easy to cause the growth and extension of cracks at the sharp end compared with the rectangular and V-shaped tail end, thereby facilitating the improvement of the overall mechanical properties of the slotted magnetic steel and reducing the risk of fracture.

[0009] The through groove is filled with an organic filler in the application, which can fill the groove while ensuring insulation, thereby avoiding the problem of easy contamination in the groove without filling and facilitating automatic installation of the magnetic steel, because the automatic installation line of the motor generally uses a vacuum suction cup, and the conventional slotted magnetic steel cannot be sucked up by the suction cup due to the gap between the grooves. Meanwhile, the organic filler can also improve the mechanical strength of the slotted magnetic steel, provide mechanical support, and avoid the problem of easy breakage of the magnetic steel during installation.

[0010] In the application, the length direction of the slotted magnetic steel and the width direction of the slotted magnetic steel are both perpendicular to the orientation direction, and the length of the slotted magnetic steel is greater than or equal to the width of the slotted magnetic steel. The height direction of the slotted magnetic steel is the direction through which the through groove penetrates.

[0011] In the application, preferably, the ratio of the groove depth of the through groove to the width of the slotted magnetic steel is 26.5%-42.5%, for example, 33%, 34%, 35%, 38% or 40%.

[0012] In the application, preferably, the ratio of the groove depth of the through groove to the length of the slotted magnetic steel is 15%-30%, for example, 17.9%, 22%, 22.2%, 22.6%, 23.4%, 25.5% or 26.8%.

[0013] In the application, preferably, the ratio of the groove depth of the through groove to the height of the slotted magnetic steel is (0.9-1.2):1, for example, 0.77:1, 0.95:1, 0.96:1, 0.97:1, 1.01:1, 1.1:1 or 1.15:1.

[0014] In the application, preferably, the ratio of the length of the slotted magnetic steel to the groove width of the through groove is (120-170):1, for example, 125:1, 150:1, 155:1, 168:1 or 172:1.

[0015] In the application, preferably, the ratio of the distance between two adjacent through grooves to the length of the slotted magnetic steel is 10%-30%, more preferably 11.8%-16.9%, for example, 16.8%. The distance between the two adjacent through grooves refers to the distance between the centers of the two adjacent through grooves.

[0016] In the application, the groove width of the through groove is preferably 0.15-0.5mm, more preferably 0.216-0.269mm, and further more preferably 0.25-0.35mm, for example, 0.269mm. When the groove width is 0.25-0.35mm, it is beneficial for effective filling of the organic filler.

[0017] In the present application, the depth of the through groove is preferably 5.9-9mm, more preferably 5.98-8.55mm, for example 7.45mm, 7.57mm or 7.85mm.

[0018] In the present application, the width of the slotted magnetic steel is preferably 5-25mm.

[0019] In the present application, the length of the slotted magnetic steel is preferably 10-40mm.

[0020] In the present application, the height of the slotted magnetic steel is preferably 1-15mm.

[0021] In the present application, the through grooves are arranged on the upper and lower surfaces of the slotted magnetic steel in a symmetrical, staggered or single-side manner. When arranged in a staggered or single-side manner, the bending strength of the slotted magnetic steel can be improved.

[0022] In the present application, the circular arc is for example a superior arc or an inferior arc.

[0023] In the present application, the number of the through grooves is preferably 4-16, more preferably 4-10. When the number of the through grooves is less than 4, the eddy current reduction effect is not good. When the number of the through grooves is greater than 10, the magnetic flux is greatly affected.

[0024] In the present application, the through grooves are for example composed of curves and / or straight lines.

[0025] In the present application, the organic filler is preferably an epoxy resin, a thermosetting adhesive or a thermoplastic plastic.

[0026] The thermosetting adhesive is for example an epoxy adhesive.

[0027] The thermoplastic plastic is for example a polypropylene plastic.

[0028] The present application also provides a preparation method of a slotted magnetic steel, which comprises slotted treatment on the upper and lower surfaces of a magnetic steel substrate.

[0029] In the present application, the slotted treatment can be conventional in the art, for example multi-wire slotted or electric spark slotted.

[0030] On the basis of common sense in the art, the above-mentioned preferred conditions can be combined arbitrarily, i.e. to obtain each preferred example of the present application.

[0031] The reagents and raw materials used in the present application are commercially available.

[0032] The positive progress effect of the present application is that:

[0033] The slotted magnetic steel of the present application has excellent magnetic and mechanical properties by selecting specific slotting direction, specific slot shape and filling material. In terms of magnetic properties, the slotted magnetic steel of the present application can significantly reduce the eddy current effect, i.e. the proportion of eddy current loss is significantly reduced, and can also significantly reduce the magnetic loss. In terms of mechanical properties, the slotted magnetic steel of the present application has high bending strength and high shear force. The preparation method of the slotted magnetic steel of the present application can also significantly reduce the cost. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The cross-sectional view of the slotted magnetic steel of Example 1 is shown in

[0035] Figure 2 The cross-sectional view of the slotted magnetic steel of Example 8 is shown in

[0036] Figure 3 The cross-sectional view of the slotted magnetic steel of Example 12 is shown in

[0037] Figure 4 The cross-sectional view of the slotted magnetic steel of Example 13 is shown in

[0038] Figure 5 The cross-sectional view of the slotted magnetic steel of Example 12 is shown in DETAILED DESCRIPTION

[0039] The present application will be further described in the following examples, but the present application is not limited to the scope of the examples. The experimental methods in the following examples without specific conditions are selected according to conventional methods and conditions, or according to the instructions of the commodity.

[0040] Examples 1-13

[0041] Examples 1-13 all use magnetic steel substrates with a size of 33.5mm x 22.42mm x 7.8mm (i.e. length x width x height) for slotting treatment to form slotted magnetic steel.

[0042] The cross-sectional view of the slotted magnetic steel of Example 1 is shown in Figure 1 The tail end of the through slot along the cross section perpendicular to the orientation direction is a circular arc, which is a superior arc, and the through slot is provided with an organic filler, which is epoxy glue, the manufacturer is Loctite, and the model is E-4HP.

[0043] The tail end of the through slot along the cross section perpendicular to the orientation direction is a circular arc, which is a superior arc, and the through slot is provided with an organic filler, which is epoxy glue, the manufacturer is Loctite, and the model is E-4HP.

[0044] The tail end of the through slot of the slotted magnetic steel of Examples 4-7 along the cross section perpendicular to the orientation direction is a circular arc, which is a superior arc, and the through slot is provided with an organic filler, which is epoxy glue, the manufacturer is Tian Shan, and the model is 1321-fs.

[0045] The cross-sectional view of the slotted magnetic steel of Example 8 is shown in Figure 2 The tail end of the through slot of the slotted magnetic steel of Example 8 along the cross section perpendicular to the orientation direction is a circular arc, which is a poor arc, and the through slot is provided with an organic filler, which is polypropylene plastic, the manufacturer is DuPont of the United States, and the model is 50E803.

[0046] The tail end of the through slot of the slotted magnetic steel of Examples 9-11 along the cross section perpendicular to the orientation direction is a circular arc, which is a poor arc, and the through slot is provided with an organic filler, which is polypropylene plastic, the manufacturer is DuPont of the United States, and the model is 50E803.

[0047] The cross-sectional view of the slotted magnetic steel of Example 12 is shown in Figure 3 The three-dimensional structure of the slotted magnetic steel of Example 12 is shown in Figure 5 The tail end of the through slot of the slotted magnetic steel of Example 12 along the cross section perpendicular to the orientation direction is a circular arc, which is a superior arc, and the through slot is provided with an organic filler, which is epoxy glue, the manufacturer is Loctite, and the model is E-4HP. The number of through slots is 8.

[0048] The cross-sectional view of the slotted magnetic steel of Example 13 is shown in Figure 4 The tail end of the through slot of the slotted magnetic steel of Example 13 along the cross section perpendicular to the orientation direction is a circular arc, which is a poor arc, and the through slot is provided with an organic filler, which is epoxy glue, the manufacturer is Loctite, and the model is E-4HP. The number of through slots is 8.

[0049] The slot depth, slot width, slot distribution type, and other parameters of the slotted magnetic steels of Examples 1-11 and Comparative Examples 1-3 are listed in Table 1.

[0050] Table 1

[0051]

[0052]

[0053] Example 1

[0054] The slotted magnetic steels prepared in Examples 1-13 were tested as follows:

[0055] The test method of the magnetic flux ratio is as follows: the magnetic flux of the unslotted magnetic steel substrate and the slotted magnetic steel after slotted in examples 1-13 is measured by the magnetic flux meter according to the reversal method; the magnetic flux ratio is calculated by the following formula: magnetic flux ratio = magnetic flux of the slotted magnetic steel after slotted in each example / magnetic flux of the magnetic steel substrate.

[0056] The test method of the eddy current loss ratio is as follows: the eddy current loss ratio of examples 1-13 is simulated by using the MAXWELL software.

[0057] The test method of the magnetic loss is as follows: the slotted magnetic steel prepared in examples 1-13 is placed in an oven for baking at 100℃ for 2h, then taken out and placed, and the magnetic flux of examples 1-13 is measured after the temperature drops to room temperature, and compared with the magnetic flux before baking. The calculation method of the magnetic loss is: (magnetic flux before baking-magnetic flux after baking) / magnetic flux before baking.

[0058] The test method of the bending strength is as follows: the slotted magnetic steel prepared in examples 1-13 is detected by using the universal electronic testing machine according to the 3-point bending test method.

[0059] The test method of the shear force is as follows: the shear force of the slotted magnetic steel prepared in examples 1-13 at the slotted position of the center of the magnetic steel is measured by using the universal electronic testing machine.

[0060] The test results of examples 1-11 and comparative examples 1-3 after the above tests are listed in table 2:

[0061] Table 2

[0062]

[0063] From the results of table 1 and table 2, it can be seen that the eddy current loss ratio of the slotted magnetic steel of the present application is less than 80%, the magnetic loss is less than 20%, the magnetic flux ratio is higher than 95%, the bending strength is higher than 16Kn / mm 2 , and the shear force is higher than 1200N. The cross section of the through slot in the slotted magnetic steel of comparative examples 1-3 is set as a rectangle or a V shape, the eddy current loss ratio and the magnetic loss increase significantly, and the bending strength and the shear force decrease significantly.

[0064] In the present application, the tail end of the cross section of the through slot is set as a circular arc shape, compared with the unslotted magnetic steel and the conventional rectangular and V-shaped tail end, the mechanical properties (bending strength, shear force, etc.) and magnetic properties (eddy current loss ratio, magnetic loss and magnetic flux ratio, etc.) of the magnetic steel can be improved.

Claims

1. A slotted magnetic steel, characterized by, The upper and lower surfaces of the slotted magnetic steel are provided with a plurality of through grooves in parallel to the orientation direction of the magnet, the tail end of the cross section of the through groove in the orientation direction of the magnet is circular arc-shaped, and a filler is arranged in the through groove; The ratio of the groove depth of the through groove to the width of the slotted magnetic steel is 26.5%-38%, the ratio of the groove depth of the through groove to the length of the slotted magnetic steel is 15%-30%, and the ratio of the groove depth of the through groove to the height of the slotted magnetic steel is (0.9-1.2):1; the ratio of the spacing between two adjacent through grooves to the length of the slotted magnetic steel is 10%-11.8%. The through grooves are symmetrically or staggeredly arranged on the upper and lower surfaces of the slotted magnetic steel.

2. The slotted magnetic steel of claim 1, wherein, The ratio of the groove depth of the through groove to the width of the slotted magnetic steel is 33%, 34%, 35% or 38%.

3. The slotted magnetic steel of claim 1, wherein the slot is formed in the center of the magnetic steel. The ratio of the groove depth of the through groove to the length of the slotted magnetic steel is 17.9%, 22%, 22.2%, 22.6%, 23.4%, 25.5% or 26.8%.

4. The slotted magnetic steel of claim 1, wherein The ratio of the groove depth of the through groove to the height of the slotted magnetic steel is 0.77:1, 0.95:1, 0.96:1, 0.97:1, 1.01:1, 1.1:1 or 1.15:

1.

5. The slotted magnetic steel of claim 1, wherein the slot has a width of 0.1 to 0.3 mm. The ratio of the length of the slotted magnetic steel to the groove width of the through groove is (120-170):

1.

6. The slotted magnetic steel of claim 5 wherein, The ratio of the length of the slotted magnetic steel to the groove width of the through groove is 125:1, 150:1, 155:1, 168:1 or 172:

1.

7. The slotted magnetic steel of claim 1, wherein the slot has a width of 0.1 to 0.3 mm. The groove width of the through groove is 0.15-0.5mm; And / or, the groove depth of the through groove is 5.9-9mm.

8. The slotted magnetic steel of claim 7 wherein, The groove width of the through groove is 0.216-0.269mm.

9. The slotted magnetic steel of claim 7 wherein, The groove width of the through groove is 0.25-0.35mm.

10. The slotted magnetic steel of claim 9, wherein the slot is formed in the center of the magnetic steel. The groove width of the through groove is 0.269mm.

11. The slotted magnetic steel of claim 7 wherein the slot is formed by a plurality of parallel grooves. The groove depth of the through groove is 5.98-8.55mm.

12. The slotted magnetic steel of claim 11, wherein the slot has a width of 0.005 to 0.015 inch. The groove depth of the through groove is 7.45mm, 7.57mm or 7.85mm.

13. The slotted magnetic steel of claim 1 wherein, The width of the slotted magnetic steel is 5-25mm; And / or, the length of the slotted magnetic steel is 10-40mm; And / or, the height of the slotted magnetic steel is 1-15mm.

14. The slotted magnetic steel of claim 1 wherein, The circular arc shape is a superior arc shape or an inferior arc shape; And / or, the number of the through grooves is 4-16.

15. The slotted magnetic steel of claim 14, wherein the slot has a width of about 0.005 inches to about 0.015 inches. The number of the through grooves is 4-10.

16. The slotted magnetic steel of claim 1, wherein The organic filler is epoxy resin, thermosetting glue or thermoplastic plastic.

17. The slotted magnetic steel of claim 16, wherein the slot has a width of about 0.005 inches to about 0.015 inches. The thermosetting glue is epoxy glue.

18. The slotted magnetic steel of claim 16, wherein the slot has a width of about 0.005 inches to about 0.015 inches. The thermoplastic plastic is polypropylene plastic.

19. A method of manufacturing a slotted magnetic steel as claimed in any one of claims 1-18, characterized in that, The preparation method of the slotted magnetic steel comprises slitting treatment on the upper and lower surfaces of the magnetic steel substrate.

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