High-precision and high-efficiency grinding wheel for titanium alloy and preparation method thereof

Abstract

The application discloses a high-precision and high-efficiency grinding titanium alloy ceramic grinding wheel and a preparation method thereof. The high-precision and high-efficiency grinding titanium alloy ceramic grinding wheel comprises a rough grinding wheel and a fine grinding wheel, and the rough grinding wheel and the fine grinding wheel are both made of green silicon carbide and a ceramic binder. In the rough grinding wheel, the green silicon carbide accounts for 82-90 wt%, and the ceramic binder accounts for 10-18 wt%. The ceramic binder is composed of clay 25-30%, feldspar 35-40%, borosilicate glass 25-30%, lithium carbonate 0.5-1%, talc powder 2.5-5%, bentonite 1.5-2.8% and dextrin powder 2-4.5%. In the fine grinding wheel, the green silicon carbide accounts for 88-92 wt%, and the ceramic binder accounts for 8-12 wt%. The ceramic binder is composed of clay 23-35%, feldspar 29-46%, borosilicate glass 21-32%, talc powder 2-3%, lithium carbonate 0.3-0.6%, dextrin powder 1.5-2.4% and bentonite 1.2-1.8%.

Description

Technical Field

[0001] This invention belongs to the field of grinding, specifically relating to a high-precision and high-efficiency grinding titanium alloy ceramic grinding wheel and its preparation method. Background Technology

[0002] TC4 titanium alloy: The material is a titanium-containing alloy metal with the composition of Ti-6Al-4V. It has the characteristics of low density, high strength and corrosion resistance.

[0003] Ceramic grinding wheel: A type of abrasive tool that uses a ceramic binder to bond abrasive grains together and form them into a certain shape.

[0004] TC4 titanium alloy is a difficult-to-grind metal, characterized by its high strength, low density, and corrosion resistance. It is widely used in aerospace and shipbuilding, for example, in aircraft blades and ship pressure hulls. In recent years, with the increasingly mature manufacturing process of TC4 titanium alloy and its high strength and low density, it has begun to be applied in the 3C (computer, communication, and consumer electronics) field, such as smartphone frames and watch cases. Due to the high strength of titanium alloy, CBN (concentrated nitrile metal) grinding wheels are typically used for grinding. However, during grinding, titanium chips easily adhere to the surface of the CBN wheel, causing clogging. Furthermore, the high hardness of CBN wheels makes them difficult to dress, resulting in low grinding efficiency and high cost. Currently, there are few processing methods using CBN wheels to grind TC4 titanium alloy, and the resulting products are expensive with poor surface quality. Ceramic grinding wheels are inexpensive and easy to dress, but grinding TC4 titanium alloy still presents many problems. Therefore, the market has been searching for a high-precision and high-efficiency ceramic grinding wheel for grinding TC4 titanium alloy.

[0005] Currently, due to the difficulty in grinding TC4 titanium alloy workpieces, its application in high-end consumer electronics is very limited. Consumer electronics products are rapidly updated with large market demand, thus requiring extremely high surface quality, precision, and processing efficiency for the selected metal casings. CBN grinding wheels, with their high hardness and wear resistance, are frequently used to grind TC4 titanium alloys, but they produce deep surface scratches. Because TC4 titanium alloy is hard, scratches easily appear on the workpiece surface and are difficult to remove in subsequent processes. During grinding, titanium shavings easily adhere to the grinding wheel surface, causing secondary damage to the workpiece surface, necessitating frequent wheel dressing. CBN grinding wheels are expensive, difficult to dress, and frequently require return to the manufacturer for processing, making the operation cumbersome and costly, unsuitable for large-scale production of high-end consumer electronics products. Furthermore, some have used ordinary ceramic grinding wheels, but these result in rapid wheel wear, exceeding the amount of workpiece material removed, and a low grinding speed of only 10-15 m / s, producing numerous surface scratches. Similarly, they are unsuitable for mass production of high-end consumer electronics products. Summary of the Invention

[0006] This invention addresses the challenges of grinding TC4 titanium alloy, such as its difficulty in grinding and tendency to accumulate chips, by developing a high-precision and high-efficiency ceramic grinding wheel and its preparation method. This grinding wheel exhibits advantages such as sharp grinding edge, long service life, and high durability when grinding titanium alloys, producing a bright, mirror-like surface on the workpiece. This invention prepares two grinding wheels with different grit sizes. When grinding titanium alloys, especially TC4 titanium alloys, a coarse-grained ceramic grinding wheel is first used to remove most of the grinding allowance, followed by a fine-grained ceramic grinding wheel for fine grinding and polishing. By combining different grit sizes, the desired surface finish can be achieved.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A high-precision and high-efficiency ceramic grinding wheel for grinding titanium alloys includes a coarse grinding wheel and a fine grinding wheel. The grinding wheels are made of green silicon carbide (GC) with a grit size ranging from F100 to F1000. Both the coarse grinding wheel and the fine grinding wheel are made of green silicon carbide and a ceramic binder. In the coarse grinding wheel, the proportions are: green silicon carbide 82-90 wt% and ceramic binder 10-18 wt%; in the fine grinding wheel, the proportions are: green silicon carbide 88-92 wt% and ceramic binder 8-12 wt%.

[0009] The ceramic binder in the coarse grinding wheel is composed of the following raw materials in the indicated mass percentages: clay 25-30%, feldspar 35-40%, borosilicate glass 25-30%, lithium carbonate 0.5-1%, talc 2.5-5%, bentonite 1.5-2.8%, and dextrin powder 2-4.5%.

[0010] The ceramic binder in the fine grinding wheel is composed of the following raw materials in the following mass percentages: clay 23%~35%, feldspar 29%~46%, borosilicate glass 21%~32%, talc powder 2%~3%, lithium carbonate 0.3%~0.6%, dextrin powder 1.5%~2.4%, and bentonite 1.2%~1.8%.

[0011] Furthermore, the green silicon carbide particle size in the coarse grinding wheel is F100~F320, and the green silicon carbide particle size in the fine grinding wheel is F400~F1000.

[0012] The preparation method of the above-mentioned high-precision and high-efficiency ceramic grinding wheel for grinding titanium alloys is as follows:

[0013] (1) Add clay, feldspar, borosilicate glass, lithium carbonate, dextrin powder, talc powder and bentonite, mix evenly to obtain a binder;

[0014] (2) Coarse grinding wheel: Pour green silicon carbide into a pot, add 1.8%~2.5% dextrin solution of the total weight of green silicon carbide and binder, stir for 10~15 minutes, then add the prepared ceramic binder, stir for another 10~15 minutes, and the molding material of the coarse grinding wheel can be obtained; Fine grinding wheel: Pour green silicon carbide, ceramic binder and 0.5%~1.5% dextrin powder of the total weight of green silicon carbide and binder together and stir for 2~4 hours, then add 1.5%~3.0% dextrin solution of the total weight of green silicon carbide and ceramic binder, stir for 10~20 minutes, and the molding material of the fine grinding wheel can be obtained;

[0015] (3) Pour the mixed material into the prepared mold, stir evenly, scrape it flat, press it into shape, and dry it to obtain a grinding wheel blank;

[0016] (4) Place it in a high-temperature kiln and fire it at 1030~1070℃ for 4~8 hours. The hardness range of the coarse grinding wheel is M~P, and the hardness range of the fine grinding wheel is K~M. The corresponding grinding wheel can be obtained.

[0017] Furthermore, in step (3), pressing refers to pressing 2 to 3 times under the same pressure and holding time at a pressure of 13 to 20 MPa and a holding time of 5 to 30 s.

[0018] Furthermore, in step (3), drying refers to drying at 60~80℃ for 12h~24h.

[0019] Furthermore, the concentration of dextrin solution in step (2) is 40~60wt%.

[0020] Further, in step (4), the temperature is increased to 1030~1070℃ at a heating rate of 1~5℃ / min.

[0021] The above-mentioned ceramic grinding wheel is used in the grinding of titanium alloys. After the coarse grinding wheel removes 50% to 80% of the grinding allowance on the workpiece surface, the fine grinding wheel is used for fine grinding to remove 15% to 35% of the grinding allowance. Finally, polishing is performed to remove 5% of the grinding allowance (grinding allowance: the difference between the size before and after grinding).

[0022] This grinding wheel is used for grinding mobile phone frames or watch cases made of TC4 material. These metal parts, after casting, have varying surface dimensions, typically with a grinding allowance of 0.02~0.10mm. Grinding is required to remove this allowance, followed by polishing to obtain a qualified product. The coarse grinding wheel removes 60%~80% of the grinding allowance, while the fine grinding wheel removes scratches from the phone or watch case, removing 15%~35%. Finally, polishing removes the remaining 5% of the grinding allowance. This invention's grinding wheel is used for processing iPhone, Huawei, and Xiaomi smartwatch frames.

[0023] Currently, many publications report on ceramic grinding wheels for grinding titanium alloys. While these wheels are made of materials suitable for grinding titanium alloys, they do not report on key parameters such as workpiece surface quality, grinding efficiency, wheel life, and durability. Consequently, they are not widely used in the market. To address this technical problem, the ceramic grinding wheel created in this invention can achieve a surface roughness of 0.05μm~0.15μm according to customer requirements. After simple polishing, a mirror-like finish can be achieved. Furthermore, the grinding wheel boasts high grinding efficiency, with speeds reaching 30~60m / s, and high durability.

[0024] This invention designs two ceramic grinding wheels with different hardnesses. First, a coarser-grit wheel is used to remove a large amount of grinding allowance. Titanium alloys have higher hardness than other metals, while other metals, such as stainless steel, have lower hardness and are very easy to grind. After grinding with one wheel, scratches on the workpiece surface are easily eliminated in the next process. After removing 50% to 80% of the grinding allowance using the coarse-grit wheel, a second, finer-grit wheel is used for finishing, removing 15% to 45% of the allowance. Finally, polishing removes the remaining 5%. This combined grinding of the two wheels effectively removes excess material from the titanium alloy workpiece surface with very high processing efficiency, and effectively eliminates surface scratches. Attached Figure Description

[0025] Figure 1 These are photographs of the coarse grinding wheel and the fine grinding wheel obtained in Embodiment 1 of the present invention;

[0026] Figure 2 This is a photograph of the coarse grinding wheel obtained in Embodiment 2 of the present invention. Detailed Implementation

[0027] The ceramic binder in the following examples and comparative examples consists of the following components by mass percentage: clay 29%, feldspar 38%, borosilicate glass 26.5%, lithium carbonate 0.5%, talc 2.5%, bentonite 1.5%, and dextrin powder 2%. In use, the raw materials are placed in a container according to the specified proportions and stirred for 3 hours using a three-dimensional mixer at a speed of 50 r / min to obtain the ceramic binder.

[0028] Example 1:

[0029] The formula for the coarse grinding wheel is as follows: 83 wt% green silicon carbide F150 and 17 wt% ceramic binder. The preparation process is as follows: Pour the green silicon carbide F150 into a pot, then add 2% dextrin solution (42 wt% concentration) based on the total weight of the green silicon carbide F150 and ceramic binder, stir for 10 minutes, then add the ceramic binder, stir for another 10 minutes, and pass through a 16-mesh sieve. Pour the mixed material into a prepared mold, apply pressure of 15 MPa, hold for 10 seconds, and press twice. Place the grinding wheel blank in a 60℃ drying oven for 12 hours, then place it in a kiln and fire at 1040℃ for 5 hours at a heating rate of 2.2℃ / min. After firing, lower the kiln temperature to room temperature and check if the grinding wheel hardness is grade M. If it reaches grade M, the grinding wheel is obtained.

[0030] The formula for the fine grinding wheel is as follows: 87.5 wt% green silicon carbide F400 and 12.5 wt% ceramic binder. The preparation process is as follows: Mix the green silicon carbide F400 and ceramic binder together, add 0.8% dextrin powder (by weight of the total green silicon carbide F400 and ceramic binder), stir for 2 hours, then add 1.8% dextrin solution (42 wt% concentration) and stir for 15 minutes. Pass the mixture through a 30-mesh sieve. Pour the mixture into a prepared mold, apply pressure of 17.6 MPa, hold for 15 seconds, and press twice. Place the grinding wheel blank in a 60℃ drying oven for 24 hours, then place it in a kiln and fire at 1055℃ for 7 hours at a heating rate of 1.5℃ / min. After firing, lower the kiln temperature to room temperature and test the hardness of the grinding wheel to K grade. A K grade grinding wheel is obtained. For detailed photos of the coarse grinding wheel and the fine grinding wheel obtained above, please refer to [link / reference]. Figure 1 The prepared coarse grinding wheel and fine grinding wheel were subjected to grinding experiments, and the specific results are shown in the table below.

[0031]

[0032] P: refers to the shape of the grinding wheel; P means a flat grinding wheel. 125×20×32: represents the size of the grinding wheel; 125 refers to the outer diameter of the grinding wheel, 20 refers to the thickness of the grinding wheel, and 32 refers to the bore diameter of the grinding wheel, in mm. K, L, M, and P represent the hardness grades of the grinding wheel.

[0033] As can be seen from the table above, by first using a GC F150M coarse grinding wheel to remove the 0.06mm grinding allowance of the titanium alloy workpiece, the surface roughness reaches 0.3μm. Then, by using a GC F400K fine grinding wheel to remove the 0.015mm grinding allowance, the surface roughness reaches below 0.15μm, resulting in a better workpiece grinding surface.

[0034] Example 2:

[0035] The formula for the coarse grinding wheel is as follows: 90 wt% green silicon carbide F320 and 10 wt% ceramic binder. The preparation process is as follows: Pour the green silicon carbide F320 into a pot, then add 2.2% dextrin solution (42 wt% concentration) based on the total weight of the green silicon carbide F320 and ceramic binder, stir for 10 minutes, then add the aforementioned ceramic binder, stir for another 10 minutes, and pass through a 20-mesh sieve. Pour the mixed material into a prepared mold, apply pressure of 16 MPa, hold for 10 seconds, and press twice. Place the grinding wheel blank in a 60℃ drying oven for 12 hours, then place it in a kiln and fire at 1040℃ for 6 hours at a heating rate of 2.2℃ / min. After firing, lower the kiln temperature to room temperature and test the hardness of the grinding wheel to P grade. If the hardness reaches P grade, the grinding wheel is obtained.

[0036] The formula for the fine grinding wheel is as follows: 90.5 wt% green silicon carbide F600 and 9.5 wt% ceramic binder. The preparation process is as follows: Mix the green silicon carbide F600 and ceramic binder together, add 1.0% dextrin powder (based on the total weight of the green silicon carbide F600 and ceramic binder), stir for 2.5 hours, then add 1.9% dextrin solution (42 wt% concentration) based on the total weight of the green silicon carbide F600 and ceramic binder, stir for 15 minutes, and pass through a 30-mesh sieve. Pour the mixed material into a prepared mold, apply pressure of 18 MPa, hold for 20 seconds, and press twice. Place the grinding wheel blank in a 60℃ drying oven for 24 hours, then place it in a kiln and fire at 1055℃ for 8 hours at a heating rate of 1.2℃ / min. After firing, lower the kiln temperature to room temperature and check if the grinding wheel hardness is L. If it reaches grade K, the grinding wheel is obtained.

[0037] For detailed photos of the coarse grinding wheel prepared above, please refer to [link / reference]. Figure 2 The prepared coarse grinding wheel and fine grinding wheel were subjected to grinding experiments, and the specific results are shown in the table below.

[0038]

[0039] As can be seen from the table above, by using a combination of coarse and fine grinding wheels, the GC F320P achieved a durability of 22 pieces dressed and the GC F600L achieved a durability of 55 pieces dressed, reducing the surface roughness of the workpiece to below 0.1μm and obtaining a better workpiece grinding surface.

[0040] Comparative Example 1:

[0041] Coarse grinding wheel: The wheel formula is shown in the table below.

[0042] Preparation method: Pour green silicon carbide F220 into a pot, add 2% dextrin solution (concentration 42wt%) of the total weight of green silicon carbide F220 and the above ceramic binder, stir for 10 min, add ceramic binder according to the formula in the table below, stir again for 10 min, and pass through a 20-mesh sieve. Pour the mixed material into the prepared mold, press at a pressure of 17 MPa, hold for 10 s, press twice, put the grinding wheel blank into a drying oven at 60℃ for 12 h, and then put it into a kiln to fire at 1050℃ for 6 h, with a heating rate of 2.1℃ / min. After firing, the following grinding wheels can be obtained.

[0043]

[0044] As can be seen from the table above, grinding wheels with a green silicon carbide ratio lower than that in the formulation range of this application are consumed quickly during use, requiring dressing once every 15 pieces, resulting in a short service life and low efficiency. Grinding wheels with a green silicon carbide ratio higher than that in the formulation range of this application are prone to burning the workpiece during grinding, requiring constant dressing of the grinding wheel, resulting in low grinding efficiency. Grinding wheels with a green silicon carbide ratio within the range of this application have high durability and high grinding efficiency.

[0045] Comparative Example 2:

[0046] Fine grinding wheels: The wheel formula is shown in the table below.

[0047] Preparation method: Green silicon carbide F400 and ceramic binder are mixed together according to the formula ratio in the table below. 0.8% dextrin powder (based on the total weight of green silicon carbide F400 and ceramic binder) is added and stirred for 2 hours. Then, 1.9% dextrin solution (42wt%) (based on the total weight of green silicon carbide F400 and binder) is added and stirred for 15 minutes, then passed through a 30-mesh sieve. The mixed material is poured into a prepared mold, pressed at a pressure of 17.6 MPa for 20 seconds, and pressed twice. The grinding wheel blank is then dried in a 60℃ drying oven for 24 hours, and then fired in a kiln at 1055℃ for 7 hours at a heating rate of 1.5℃ / min. After firing, the kiln temperature is lowered to room temperature to obtain the following grinding wheel.

[0048]

[0049] As can be seen from the table above, for fine grinding wheels, grinding wheels with a green silicon carbide ratio lower than that in the formulation range of this application have low durability during use. Grinding wheels with a green silicon carbide ratio higher than that in the formulation range of this application are prone to burning the workpiece during grinding. At the same time, titanium shavings adhere to the surface of the grinding wheel, causing new scratches on the workpiece surface, reducing the roughness, requiring constant dressing of the grinding wheel, and resulting in low grinding efficiency. Grinding wheels within the formulation range of this application have high durability and high grinding efficiency.

[0050] Comparative Example 3:

[0051] The grinding effects of using the coarse grinding wheel or fine grinding wheel prepared in Example 1 alone to grind the titanium alloy watch case, and using both the coarse grinding wheel and fine grinding wheel prepared in Example 1 simultaneously, are shown in the table below.

[0052]

[0053] As can be seen from the table above, Scheme 2 yields the best results. Using only a single coarse grinding wheel results in low wheel durability and poor surface quality. Using only a single fine grinding wheel also results in low wheel durability, requiring frequent dressing and leading to rapid wheel wear and low overall durability. Therefore, combining coarse and fine grinding wheels is superior. The coarse grinding wheel removes most of the grinding allowance, while the fine grinding wheel and polishing remove the remaining allowance. This combination achieves both better grinding results and improved grinding efficiency.

Claims

1. A high-precision and high-efficiency ceramic grinding wheel for grinding titanium alloys, characterized in that, The grinding wheels include coarse grinding wheels and fine grinding wheels, both made of green silicon carbide and a ceramic binder. In the coarse grinding wheel: 82-90 wt% green silicon carbide and 10-18 wt% ceramic binder; in the fine grinding wheel: 88-92 wt% green silicon carbide and 8-12 wt% ceramic binder. The ceramic binder in the coarse grinding wheel is composed of the following raw materials by mass percentage: clay 25-30%, feldspar 35-40%, borosilicate glass 25-30%, lithium carbonate 0.5-1%, talc powder 2.5-5%, bentonite 1.5-2.8%, and dextrin powder 2-4.5%; the ceramic binder in the fine grinding wheel is composed of the following raw materials by mass percentage: clay 23%-35%, feldspar 29%-46%, borosilicate glass 21%-32%, talc powder 2%-3%, lithium carbonate 0.3%-0.6%, dextrin powder 1.5%-2.4%, and bentonite 1.2%-1.8%. The green silicon carbide particle size in the coarse grinding wheel is F100~F320, and the green silicon carbide particle size in the fine grinding wheel is F400~F1000.

2. The method for preparing a high-precision and high-efficiency ceramic grinding wheel for grinding titanium alloys according to claim 1, characterized in that, The process is as follows: (1) Add clay, feldspar, borosilicate glass, lithium carbonate, dextrin powder, talc powder and bentonite, mix evenly to obtain a binder; (2) Coarse grinding wheel: Pour green silicon carbide into a pot, add 1.8%~2.5% dextrin solution of the total weight of green silicon carbide and binder, stir for 10~15 minutes, then add the prepared ceramic binder, stir for another 10~15 minutes, and the molding material of the coarse grinding wheel can be obtained; Fine grinding wheel: Pour green silicon carbide, ceramic binder and 0.5%~1.5% dextrin powder of the total weight of green silicon carbide and binder together and stir for 2~4 hours, then add 1.5%~3.0% dextrin solution of the total weight of green silicon carbide and ceramic binder, stir for 10~20 minutes, and the molding material of the fine grinding wheel can be obtained; (3) Pour the mixed material into the prepared mold, stir evenly, scrape it flat, press it into shape, and dry it to obtain a grinding wheel blank; (4) Place it in a high-temperature kiln and fire it at 1030~1070℃ for 4~8 hours. The hardness range of the coarse grinding wheel is M~P, and the hardness range of the fine grinding wheel is K~M. The corresponding grinding wheel can be obtained.

3. The method for preparing a high-precision and high-efficiency ceramic grinding wheel for grinding titanium alloys according to claim 2, characterized in that, In step (3), pressing refers to pressing 2 to 3 times at a pressure of 13 to 20 MPa and a holding time of 5 to 30 seconds, with the same pressure and holding time.

4. The method for preparing a high-precision and high-efficiency ceramic grinding wheel for grinding titanium alloys according to claim 2, characterized in that, In step (3), drying refers to drying at 60~80℃ for 12h~24h.

5. The method for preparing a high-precision and high-efficiency ceramic grinding wheel for grinding titanium alloys according to claim 2, characterized in that, The concentration of dextrin solution in step (2) is 40~60wt%.

6. The method for preparing a high-precision and high-efficiency ceramic grinding wheel for grinding titanium alloys according to claim 2, characterized in that, Step (4) Heat the temperature to 1030~1070℃ at a heating rate of 1~5℃ / min.

7. The application of the ceramic grinding wheel according to claim 1 in grinding titanium alloys, characterized in that, After removing 50% to 80% of the grinding allowance from the workpiece surface using a coarse grinding wheel, a fine grinding wheel is used to remove 15% to 35% of the grinding allowance. Finally, the remaining grinding allowance is removed by polishing.

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