A magnetic material polishing grinding wheel and a preparation method thereof

Abstract

A kind of magnetic material polishing grinding wheel is composed of matrix and abrasive layer, and the abrasive layer is composed of diamond abrasive and binder, and the weight percentage of the abrasive layer and the binder is as follows: diamond abrasive 7-20%; binder includes epoxy resin powder 35-45%, nano-silica sol 10-20%, ultra-fine cerium oxide and lanthanum oxide composition 5-10%, reinforcing fiber 5-10%, pore-forming agent 5-15%. By adjusting the weight of each component of the abrasive layer and the binder, the high surface quality and high inductance requirements of the product can be met, and the problems of poor surface quality and low processing efficiency of such products are solved. At the same time, the grinding wheel has the characteristics of long service life and good grinding effect.

Description

Technical Field

[0001] This invention belongs to the field of superhard abrasive technology, and particularly relates to a polishing wheel for magnetic materials and its preparation method. Background Technology

[0002] Magnetic materials are an important class of basic functional materials with a wide range of applications, including electronics, information, power tools, automobiles, and home appliances. As a clean energy source, magnetic materials are increasingly being used in emerging fields such as energy conservation and environmental protection, new energy, electric vehicles, smart cities, and smart earth. As one of the key industries for national development, its development is receiving strong support from national industrial policies.

[0003] Magnetic material workpieces have extremely high requirements for surface quality, product consistency, and inductance consistency. Traditional resin polishing wheels and their structures have problems such as many workpiece scratches, poor consistency, slow polishing speed, and impact on inductance, which cannot meet the high-quality requirements of magnetic materials. Therefore, it is urgent to develop a new type of polishing wheel suitable for magnetic materials to meet market demand. Summary of the Invention

[0004] The purpose of this invention is to provide a polishing wheel for magnetic materials and its preparation method. By adjusting the ratio of binder and diamond, the surface quality of magnetic material products is significantly improved, and the average life of the polishing wheel is increased. The polishing wheel has good shape retention and high consistency of magnetic material products. Moreover, it does not contain metal fillers, resulting in high inductance of magnetic material products.

[0005] To achieve the above objectives, the specific technical solution of the present invention for a polishing wheel for magnetic materials and its preparation method is as follows:

[0006] A polishing wheel for magnetic materials includes a substrate and an abrasive layer attached to the surface of the substrate.

[0007] As a further improvement of the present invention, the abrasive layers are, from the outside to the inside, a main abrasive layer, a second abrasive layer and a third abrasive layer.

[0008] The three-layer abrasive structure and its arrangement facilitate the discharge of grinding fluid and chips, reduce grinding resistance during grinding, and effectively prevent scratches while maintaining sharpness.

[0009] As a further improvement of the present invention, the abrasive layer comprises diamond abrasive and a binder, wherein the binder comprises epoxy resin, nano silica sol, a composition of ultrafine cerium oxide and lanthanum oxide, reinforcing fibers, and a pore-forming agent.

[0010] As a further improvement of the present invention, the abrasive layer comprises the following components by weight percentage: 7% to 20% diamond abrasive; 35% to 45% epoxy resin; 10% to 20% nano-silica sol; 5% to 10% ultrafine cerium oxide and lanthanum oxide composition; 5% to 10% reinforcing fiber; and 5% to 15% pore-forming agent.

[0011] As a further improvement of the present invention, the diamond abrasive comprises single-crystal diamond with a particle size of 5-20 μm and polycrystalline nickel-plated diamond with a particle size of 5-20 μm, with a mass ratio of 3:1.

[0012] The diamond used is high-strength, high-purity single-crystal diamond with regular crystal shape and concentrated grain size distribution, which has both heat resistance and service life; the polycrystalline nickel-plated diamond is preferably coated with 30% nickel, which has both sharpness and service life.

[0013] As a further improvement of the present invention, the epoxy resin has a particle size of 30-50 μm and a hardness of HRF 50-70, making it a low-hardness resin that can protect the product surface, reduce scratches during extrusion and grinding; the nano-silica sol has a particle size of 20-40 nanometers, and the silica sol undergoes special surface treatment to effectively avoid the problem of micro-powder agglomeration; the ultrafine cerium oxide and lanthanum oxide have a particle size of 1-3 μm and a mass ratio of 3:1. Cerium oxide and lanthanum oxide have a beneficial effect on improving the product's varnishing speed, and the effect is even better when used together; The reinforcing fiber is carbon fiber or alumina fiber with an aspect ratio not exceeding 12 and a diameter less than 28 μm. The reinforcing fiber can effectively improve the impact resistance of the grinding wheel, avoid rapid wear of the grinding wheel under high-speed grinding conditions, thereby affecting the machining dimensions of the workpiece and improving product consistency. The pore-forming agent is sodium sulfate, sodium sulfite, or sodium bicarbonate with a particle size of 40-60 micrometers. The pore-forming agent can play a role in chip containment and improving the self-sharpening property of the grinding wheel, effectively avoiding scratches caused by grinding wheel clogging, while reducing the frequency of grinding wheel dressing and improving grinding wheel life.

[0014] A method for preparing a polishing wheel for magnetic materials, characterized by comprising the following steps:

[0015] S1. Add 7%–20% diamond, 10%–20% nano silica sol, 5%–10% ultrafine cerium oxide and ultrafine lanthanum oxide, and 5%–10% reinforcing fiber to acetone or ethanol solution by weight percentage, stir ultrasonically until homogeneous, and stir for no less than 40 minutes. Dry at 100°C to obtain the mixture.

[0016] S2. Pour 35%–45% epoxy resin, 5%–15% pore-forming agent, and the mixture obtained in S1 into an injection molding machine by weight percentage, and injection mold to obtain an abrasive ring;

[0017] S3. Embed the abrasive ring obtained in S2 into graphite particles, place the whole assembly in an oven, and cure it into shape.

[0018] S4. The grinding wheel can be obtained by processing the solidified abrasive ring obtained in S3.

[0019] A polishing wheel for magnetic materials is used in the precision polishing of magnetic materials.

[0020] Beneficial effects:

[0021] 1. The three-layer abrasive ring and its arrangement facilitate the discharge of grinding fluid and play a role in chip containment and heat dissipation. Compared with the single-layer abrasive ring of ordinary grinding wheels, it can effectively avoid scratches while also having the characteristics of sharpness.

[0022] 2. The combined use of single-crystal high-strength diamond and polycrystalline nickel-plated diamond provides both wear resistance and sharpness, thus extending the service life of the grinding wheel. At the same time, the selection of diamonds with a concentrated particle size can improve the surface quality of the product, resulting in good surface consistency.

[0023] 3. Low-hardness epoxy resin acts as a binder, which can prevent the grinding wheel from undergoing rapid profile changes due to severe vibration during high-speed grinding, resulting in uneven grinding patterns and low dimensional accuracy. It can effectively improve the impact resistance of the grinding wheel. At the same time, the low-hardness grinding wheel is a compression grinding process, which avoids the damage to high-brittleness, low-hardness magnetic materials caused by the high rigidity of traditional grinding wheels. It has a beneficial effect on improving product surface quality and yield.

[0024] 4. Nano silica sol, with a specially treated surface, can effectively avoid scratches caused by colloidal agglomeration. At the same time, nano silica sol particles have a large specific surface area, high dispersibility and permeability, resulting in minimal damage to the surface of the polished workpiece. Silica sol has advantages such as controllable particle size, moderate hardness, low viscosity, low adhesion, and easy cleaning after polishing, all of which are beneficial to the polishing of magnetic materials.

[0025] 5. Both ultrafine cerium oxide and ultrafine lanthanum oxide have beneficial effects on improving the polishing rate of magnetic materials. When used together, a small amount can achieve the same effect and greatly improve the polishing rate.

[0026] 6. The addition of carbon fiber or alumina fiber can effectively improve the impact resistance of the grinding wheel, prevent the grinding wheel from being worn too quickly under high-speed polishing conditions, and avoid affecting the machining dimensions of the workpiece. The addition of reinforcing fibers has significant beneficial effects on improving the grinding wheel life and the consistency of the ground workpiece.

[0027] 7. The addition of a pore-forming agent can help to contain chips and improve the self-sharpening properties of the grinding wheel, effectively preventing scratches caused by grinding wheel clogging, reducing grinding wheel dressing issues, and improving the overall lifespan of the grinding wheel.

[0028] 8. The injection molding method of this product can ensure the consistency and uniformity of the mixture. Compared with traditional grinding wheels, the mixing machine mixes and presses the mixture, saving a lot of time, while greatly improving the consistency and uniformity. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a polishing wheel structure for polishing magnetic materials according to the present invention;

[0030] Figure 2 This is a SEM image of the grinding wheel of the present invention;

[0031] Explanation of markings in the figure: 1. Matrix. Detailed Implementation

[0032] To better understand the purpose, structure, and function of this invention, the following detailed description, in conjunction with the accompanying drawings, provides an overview of a polishing wheel for magnetic materials and its preparation method.

[0033] Implementation example:

[0034] The polishing wheel of this invention has a cup-shaped structure, as shown in the schematic diagram below. Figure 1 As shown, there are no restrictions on the specifications of the grinding wheel. For ease of comparison, the specifications of the grinding wheel in this invention are all 6A2-400*60*250*15(5+5+5)*10.

[0035] Example 1:

[0036] A polishing wheel for magnetic materials is provided, comprising diamond abrasive, epoxy resin powder, nano-silica sol, ultrafine cerium dioxide and lanthanum oxide combined powder, reinforcing fibers, and a pore-forming agent. The specific weight ratios of each component are shown in Table 1.

[0037] raw material Diamond 1 Diamond 2 Epoxy resin silicon dioxide weight ratio 6 2 45 10 Specification 5-20um / single crystal 5-20µm / polycrystalline nickel plating 30-50um Sol-type 20-40nm raw material Cerium oxide Lanthanum oxide carbon fiber Na2SO4 weight ratio 6.75 2.25 6 12 Specification 1-3um 1-3um Φ2*250 40-60um

[0038] Table 1

[0039] The preparation method of the above-mentioned polishing wheel for magnetic materials specifically includes the following steps:

[0040] S1. Add 7%–20% diamond, 10%–20% nano silica sol, 5%–10% ultrafine cerium oxide and ultrafine lanthanum oxide, and 5%–10% reinforcing fiber to acetone or ethanol solution by weight percentage, stir ultrasonically until homogeneous, and stir for no less than 40 minutes. Dry at 100°C to obtain the mixture.

[0041] S2. Pour 35%–45% epoxy resin, 5%–15% pore-forming agent, and the mixture obtained in S1 into an injection molding machine by weight percentage, and injection mold to obtain an abrasive ring;

[0042] S3. Embed the abrasive ring obtained in S2 into graphite particles, place the whole assembly in an oven, and cure it into shape.

[0043] S4. The grinding wheel can be obtained by processing the solidified abrasive ring obtained in S3.

[0044] Example 2

[0045] The specific weight ratios for each component in this embodiment are shown in Table 2:

[0046] raw material Diamond 1 Diamond 2 Epoxy resin silicon dioxide weight 15 5 40 15 Specification 5-20um / JR1 5-20um / BRD-N30 30-50um Sol-type 20-40nm raw material Cerium oxide Lanthanum oxide carbon fiber Na2SO4 weight 3.75 1.25 5 15 Specification 1-3um 1-3um Φ2*250 40-60um

[0047] Table 2

[0048] The preparation method of this magnetic material polishing wheel is the same as that in Example 1.

[0049] The polishing wheel life, polishing effect of the magnetic material surface, and consistency of the magnetic material surface inductance of the two embodiments described above were tested and the results are shown in Table 3.

[0050] Polishing life / disc Magnetic material surface scratches Surface inductance uniformity of magnetic materials Example 1 685 No obvious scratches good Example 2 550 No obvious scratches good

[0051] Table 3

[0052] The above two embodiments are merely representative examples of polishing wheels for magnetic materials. Test results show that when the weight composition of the polishing wheel is 7%–20% diamond abrasive, 35%–45% epoxy resin powder, 10%–20% nano-silica sol, 5%–10% cerium oxide and lanthanum oxide composition, 5%–10% reinforcing fiber, and 5%–15% pore-forming agent, the surface of the polished magnetic material has no obvious wear marks, and the inductance consistency is good; moreover, the lifespan of the polishing wheel is over 500 discs.

[0053] To better illustrate the advantages of this magnetic material polishing wheel compared to existing technologies, the following comparative examples are provided.

[0054] Comparative Example 1:

[0055] The conventional grinding wheel structure, abrasive layer ratio, and mixing method are the same as in Example 1, and the same process parameters are used to process the magnetic material.

[0056] Comparative Example 2:

[0057] The grinding wheel structure and abrasive layer ratio are the same as in Example 1. A conventional three-dimensional mixer is used for mixing. Everything else is the same as in Example 1.

[0058] Comparative Example 3:

[0059] The grinding wheel structure, mixing method, and abrasive layer ratio are the same as in Example 1, and the diamond used in all cases is single-crystal diamond.

[0060] Comparative Example 4:

[0061] The grinding wheel structure is the same, the mixing method is the same, the abrasive layer ratio is the same as in Example 1, and the resin is replaced with ordinary commercially available phenolic resin for grinding wheels.

[0062] Comparative Example 5:

[0063] The grinding wheel structure is the same, the mixing method is the same, the abrasive layer ratio is the same as in Example 2, and the nano silica sol is replaced with ordinary silica of the same specification.

[0064] Comparative Example 6:

[0065] The grinding wheel structure is the same, the mixing method is the same, the abrasive layer ratio is the same as in Example 2, and lanthanum oxide is replaced with cerium oxide.

[0066] Comparative Example 7:

[0067] The grinding wheel structure and mixing method are the same, but no carbon fiber is added. The remaining components are the same as in Example 2, except that the carbon fiber is replaced by the other components in equal proportion.

[0068] Comparative Example 8:

[0069] The grinding wheel structure and mixing method are the same, no pore-forming agent is added, and the remaining components are the same as in Example 2. The pore-forming agent is replaced by the remaining components in equal proportion.

[0070] The results are shown in Table 4:

[0071]

[0072] Table 4

[0073] The above results indicate that:

[0074] Example 1 and Comparative Example 1: The three-layer abrasive ring structure is effective in improving the surface quality of magnetic materials and enhancing inductance consistency; compared with the ordinary single-ring structure, the three-ring structure is beneficial for heat dissipation of chips, while also improving sharpness and preventing scratches caused by chips not being discharged in time.

[0075] Example 1 and Comparative Example 2: Conventional mixing methods have poor uniformity and consistency in mixing fine and ultrafine diamond and fillers, resulting in poor surface quality and inductance consistency of the workpiece. Injection molding has obvious advantages due to its strong shear and short mixing time, and the mixing effect is better than conventional mixing methods.

[0076] Example 1 and Comparative Example 3: The combined use of polycrystalline nickel-plated diamond and single-crystal diamond is beneficial to improving the life of the grinding wheel, and also has a certain improvement on the surface quality and inductance of the workpiece.

[0077] Example 1 and Comparative Example 4: Epoxy resin has high toughness and low strength, and its polishing effect is significantly better than that of ordinary phenolic resin. However, due to the poor self-sharpening property of ordinary phenolic resin, it requires frequent dressing, and the grinding wheel life is also significantly shorter than that of epoxy resin.

[0078]

[0079] Table 5

[0080] As shown in Table 5

[0081] Example 2 and Comparative Example 5: Compared with ordinary silica, nano silica sol can effectively avoid scratches caused by colloidal agglomeration due to special surface treatment. At the same time, nano silica sol particles have a large specific surface area, high dispersibility and permeability, and cause minimal damage to the surface of polished workpieces.

[0082] Example 2 and Comparative Example 6: Lanthanum oxide has a beneficial effect on improving the surface inductance consistency of magnetic materials. Under the same processing conditions, only a small amount of lanthanum oxide is needed to meet the inductance requirements of the workpiece.

[0083] Example 2 and Comparative Example 7: The addition of carbon fiber can significantly improve the life of the grinding wheel, and because it can improve the impact resistance of the grinding wheel, it can prevent the grinding wheel from being worn out too quickly and affecting the machining dimensions of the workpiece.

[0084] Example 2 and Comparative Example 8: The addition of a pore-forming agent can help to contain chips and improve the self-sharpening property of the grinding wheel, effectively avoid scratches caused by grinding wheel clogging, reduce the frequency of grinding wheel dressing, and improve the overall life of the grinding wheel.

[0085] The above embodiments and comparative examples are only for illustrating the effect of changing only the grinding wheel structure, mixing method or a certain component on the grinding wheel under the same conditions; in actual use, the grinding wheel structure, mixing method and formula composition will be adjusted according to the usage.

[0086] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A polishing wheel for magnetic materials, characterized in that, Includes a substrate and an abrasive layer attached to the surface of the substrate; The abrasive layer includes diamond abrasive and a binder, wherein the binder includes epoxy resin, nano silica sol, a composition of ultrafine cerium oxide and lanthanum oxide, reinforcing fibers, and a pore-forming agent; The abrasive layer comprises the following components by weight percentage: 7%–20% diamond abrasive; 35%–45% epoxy resin; 10%–20% nano-silica sol; 5%–10% ultrafine cerium oxide and lanthanum oxide composition; 5%–10% reinforcing fiber; and 5%–15% pore-forming agent.

2. The polishing wheel for magnetic materials according to claim 1, characterized in that, The abrasive layers, from the outside in, are the main abrasive layer, the second abrasive layer, and the third abrasive layer.

3. The polishing wheel for magnetic materials according to claim 1, characterized in that, The diamond abrasive comprises single-crystal diamond with a particle size of 5-20 μm and polycrystalline nickel-plated diamond with a particle size of 5-20 μm, with a mass ratio of 3:

1.

4. The polishing wheel for magnetic materials according to claim 1, characterized in that, The epoxy resin has a particle size of 30-50 μm and a hardness of HRF 50-70; the nano-silica sol has a particle size of 20-40 nm; the ultrafine cerium oxide and lanthanum oxide have a particle size of 1-3 μm and a mass ratio of 3:1; the reinforcing fiber is carbon fiber or alumina fiber with an aspect ratio not higher than 12 and a diameter less than 28 μm; the pore-forming agent is sodium sulfate, sodium sulfite, or sodium bicarbonate with a particle size of 40-60 μm.

5. A method for preparing a polishing wheel for magnetic materials, characterized in that, Includes the following steps: S1. Add 7%–20% diamond, 10%–20% nano silica sol, 5%–10% ultrafine cerium oxide and ultrafine lanthanum oxide, and 5%–10% reinforcing fiber to acetone or ethanol solution by weight percentage, stir ultrasonically until uniform, and stir for no less than 40 minutes. Dry at 100°C to obtain the mixture. S2. Pour 35%–45% epoxy resin, 5%–15% pore-forming agent, and the mixture obtained in S1 into an injection molding machine by weight percentage, and injection mold to obtain an abrasive ring; S3. Embed the abrasive ring obtained in S2 into graphite particles, place the whole assembly in an oven, and cure it into shape. S4. The grinding wheel can be obtained by processing the solidified abrasive ring obtained in S3.

6. An application of a polishing wheel for magnetic materials, characterized in that, The polishing wheel for magnetic materials according to any one of claims 1-4 is used in the precision polishing of magnetic materials.

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