Lubricating ball for manufacturing ceramic CBN (Cubic Boron Nitride) grinding wheel and preparation method of lubricating ball

Abstract

The invention provides a lubricating ball for manufacturing a ceramic CBN grinding wheel and a preparation method of the lubricating ball, and belongs to the technical field of super-hard grinding tools. The preparation method comprises the following steps that S1, a ceramic bonding agent and liquid phenolic resin are taken to be fully and evenly stirred to obtain slurry, and graphite nodules and the liquid phenolic resin are additionally taken to be evenly stirred to obtain slurry; coating the surfaces of the graphite nodules with liquid phenolic resin to obtain wetted graphite nodules; s2, the wetted graphite nodules are immersed in the slurry, the surfaces of the graphite nodules are evenly wrapped with the slurry, the graphite nodules are taken out and drained, and the graphite nodules wrapped with the ceramic bond are obtained; and S3, curing and shaping the graphite nodules coated with the ceramic bond in an inert gas atmosphere, and cooling to obtain the lubricating ball. According to the technical scheme, the grinding ratio is increased, grinding smoothness is improved, abrasion of the grinding wheel is reduced, the roughness of the workpiece is reduced, and the purposes of improving the grinding performance of the whole grinding wheel and avoiding damage to the workpiece are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of superhard abrasive tools, and in particular to a lubricating ball for manufacturing a ceramic CBN grinding wheel and a preparation method thereof. Background Art

[0002] Vitrified CBN grinding wheels, made from cubic boron nitride abrasive, are sintered into various shapes using metal powder, resin powder, and ceramic as binders for industrial grinding, polishing, and lapping. These wheels retain their inherent high hardness, low sintering temperature, high strength and toughness, and excellent abrasive holding properties. They also offer resistance to heat, oil, water, acids, and alkalis, excellent self-sharpening properties, dressability with long dressing intervals, and uniform porosity for easy cooling and chip removal. However, with the rapid development of high-speed and ultra-precision grinding technologies, industrial applications are placing higher demands on vitrified CBN grinding wheels.

[0003] Due to the diverse grinding application environments, the size of the pores naturally formed during the sintering of ceramic grinding wheels generally does not exceed 0.02mm, and the porosity is limited, which cannot provide enough space to accommodate large metal chips removed. For some special workpieces, the pores of the grinding wheel itself are difficult to meet all grinding requirements. Therefore, pore creation is widely used in ceramic CBN grinding wheels. There are two main ways to create pores in ceramic CBN grinding wheels: using particle grading to create pores and adding pore-forming agents to create pores. Particle grading pore creation controls pores by adjusting the particle size ratio of the powder in the abrasive tool formula. However, for fine grinding and high-precision abrasive tools, the powder must be fine, and the particle grading method is difficult to meet the requirements. Therefore, adding pore-forming agents becomes a more suitable pore-making method for ceramic bond CBN grinding wheels. However, the uniformity of the distribution of the pore-forming material particles in the grinding wheel is difficult to control, which can cause the grinding wheel to still have some problems such as scratching or burning the workpiece during the grinding process. Summary of the Invention

[0004] In view of this, the present invention provides a lubricating ball for the manufacture of ceramic CBN grinding wheels and a preparation method thereof, which improves the grinding ratio, increases the smoothness of the grinding, reduces grinding wheel wear, reduces the roughness of the workpiece, and achieves the purpose of increasing the grinding performance of the entire grinding wheel and avoiding damage to the workpiece.

[0005] To achieve the above object, the present invention provides a method for preparing a lubricating ball for manufacturing a vitrified CBN grinding wheel, comprising the following steps: S1, taking a ceramic binder and a liquid phenolic resin and stirring them evenly to obtain a slurry, taking graphite balls and stirring them evenly with the liquid phenolic resin, and coating the liquid phenolic resin on the surface of the graphite balls to obtain wetted graphite balls; S2, immersing the wetted graphite balls in the slurry, evenly wrapping the slurry on the surface of the graphite balls, taking out and filtering to obtain graphite balls coated with a ceramic binder; S3, curing and shaping the graphite ball coated with the ceramic binder in an inert gas atmosphere, and cooling the graphite ball to obtain a lubricating ball.

[0006] Optionally, the weight ratio of the graphite balls to the ceramic binder is 1:2.5-3.5.

[0007] Optionally, the weight of the graphite balls is a, the weight of the ceramic binder is b, the total weight of the liquid phenolic resin is 6-7% of (a+b), the weight of the liquid phenolic resin in the slurry is 0.8-1.2% of (a+b), and the weight of the liquid phenolic resin in the wetted graphite balls is 5.2-5.8% of (a+b). Optionally, the curing conditions are a temperature of 300-350° C. and a time of 2.5-3.5 hours.

[0008] Optionally, the particle size of the graphite balls is the same as the particle size of the ceramic CBN grinding wheel.

[0009] Optionally, the ceramic binder is in the form of powder particles, and the size of the powder particles is ≤35 μm.

[0010] In order to achieve the above-mentioned object, the present invention also provides a lubricating ball prepared by a method for preparing a lubricating ball for manufacturing a vitrified CBN grinding wheel.

[0011] In order to achieve the above-mentioned object, the present invention also provides a lubricating ball applied to a ceramic CBN grinding wheel. The lubricating ball is evenly mixed into the material of the ceramic CBN grinding wheel, and the ceramic CBN grinding wheel is obtained by mixing, molding, and high-temperature firing. The lubricating ball accounts for 10-18% of the total mass of the ceramic CBN grinding wheel raw material.

[0012] The above technical solution of the present invention includes at least the following beneficial effects: The technical solution provided by the present invention utilizes the characteristics of graphite and combines the properties of graphite and a ceramic binder to wrap graphite balls with the ceramic binder and shape them into lubricating balls. The ceramic powder material well protects the graphite balls in an inert gas (such as nitrogen) and solidifies and shapes into a protective film on the surface. The graphite balls are not damaged by external forces during the production process of the ceramic grinding wheel. When the grinding wheel is in use, the graphite exposed from the working layer of the grinding wheel can form a thin lubricating film on the contact surface between the grinding wheel and the workpiece, thereby reducing friction during grinding, increasing grinding smoothness, reducing grinding wheel wear, extending the service life of the grinding wheel, preventing grinding chips from adhering to the surface of the grinding wheel, improving heat dissipation, preventing burns to the workpiece, and improving the self-grinding and dressing ability of the grinding wheel. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of graphite balls in Example 1 of the present invention; Figure 2This is a schematic diagram of the process in Example 1 of the present invention; Figure 3 Schematic diagram of the grinding test system of the present invention; Figure 4 This is a comparison chart of the grinding ratio results of the test of the present invention; Figure 5 This is a comparison chart of the grinding power results of the test of the present invention; Figure 6 This is a comparison chart of the roundness and roughness results of the workpiece surface profile tested in the present invention. DETAILED DESCRIPTION

[0014] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be combined with the appended drawings of the embodiments of the present invention. Figures 1 to 6 , clearly and completely describing the technical solutions of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments derived by ordinary technicians in this field fall within the scope of protection of the present invention.

[0015] Example 1 The present invention provides a method for preparing a lubricating ball for manufacturing a ceramic CBN grinding wheel, comprising the following steps: a. Take out 100 grams of graphite spheres with uniform particles. The size of the graphite spheres is the same as the particle size of the ceramic CBN grinding wheel.

[0016] b. The weight ratio of graphite balls to ceramic binder is 1:3, and 300 grams of ceramic binder with a particle size of 35 μm is selected.

[0017] c. The total weight of the liquid phenolic resin is 6.25% of the total weight of the graphite balls and the ceramic binder. Take 25 grams of liquid phenolic resin and divide it into two parts: one part is 4 grams, which is 1% of the total weight, and the other part is 21 grams, which is 5.25% of the total weight.

[0018] d. Thoroughly mix 300 grams of ceramic binder and 21 grams of liquid phenolic resin to obtain a slurry. Separately, thoroughly mix 100 grams of graphite spheres and 4 grams of liquid phenolic resin. Apply the liquid phenolic resin to the surface of the graphite spheres to obtain wetted graphite spheres.

[0019] e. Immerse the moistened graphite balls in the slurry, fully wrap the ceramic binder on the surface of the graphite balls, then remove them and filter them dry.

[0020] f. Place the graphite balls wrapped with binder in an inert gas nitrogen atmosphere, cure at 320℃ for 3 hours to set the shape, and cool in the furnace.

[0021] Graphite ball schematic diagram see Figure 1, see the schematic diagram of Example 1 Figure 2 .

[0022] Example 2 The present invention provides a method for preparing a lubricating ball for manufacturing a ceramic CBN grinding wheel, comprising the following steps: a. Take out 100 grams of graphite spheres with uniform particles. The size of the graphite spheres is the same as the particle size of the ceramic CBN grinding wheel.

[0023] b. The weight ratio of graphite balls to ceramic binder is 1:3, and 300 grams of ceramic binder with a particle size of 35 μm is selected.

[0024] c. The total weight of the liquid phenolic resin is 6% of the total weight of the graphite balls and the ceramic binder. Take 24 grams of liquid phenolic resin and divide it into two parts: one part is 3.2 grams, which is 0.8% of the total weight, and the other part is 20.8 grams, which is 5.2% of the total weight.

[0025] d. Thoroughly mix 300 grams of ceramic binder and 20.8 grams of liquid phenolic resin to obtain a slurry. Separately, thoroughly mix 100 grams of graphite spheres and 3.2 grams of liquid phenolic resin. Apply the liquid phenolic resin to the surface of the graphite spheres to obtain wetted graphite spheres.

[0026] e. Immerse the moistened graphite balls in the slurry, fully wrap the ceramic binder on the surface of the graphite balls, then remove them and filter them dry.

[0027] f. Place the graphite balls wrapped with the binder in an inert gas nitrogen atmosphere, cure at 300℃ for 2.5 hours to set the shape, and cool in the furnace.

[0028] Example 3 The present invention provides a method for preparing a lubricating ball for manufacturing a ceramic CBN grinding wheel, comprising the following steps: a. Take out 100 grams of graphite spheres with uniform particles. The size of the graphite spheres is the same as the particle size of the ceramic CBN grinding wheel.

[0029] b. The weight ratio of graphite balls to ceramic binder is 1:3, and 300 grams of ceramic binder with a particle size of 35 μm is selected.

[0030] c. The total weight of the liquid phenolic resin is 7% of the total weight of the graphite balls and the ceramic binder. Take 28 grams of liquid phenolic resin and divide it into two parts: one part is 4.8 grams, which is 1.2% of the total weight, and the other part is 23.2 grams, which is 5.8% of the total weight.

[0031] d. Thoroughly mix 300 grams of ceramic binder and 23.2 grams of liquid phenolic resin to obtain a slurry. Separately, thoroughly mix 100 grams of graphite spheres and 4.8 grams of liquid phenolic resin. Apply the liquid phenolic resin to the surface of the graphite spheres to obtain wetted graphite spheres.

[0032] e. Immerse the moistened graphite balls in the slurry, fully wrap the ceramic binder on the surface of the graphite balls, then remove them and filter them dry.

[0033] f. Place the graphite balls wrapped with the binder in an inert gas nitrogen atmosphere, cure at 350℃ for 3.5 hours to set the shape, and cool in the furnace.

[0034] Example 4 Compared with Example 1, the only difference is that the weight ratio of graphite balls to the ceramic binder is 1:2.5.

[0035] Example 5 Compared with Example 1, the only difference is that the weight ratio of graphite balls to the ceramic binder is 1:3.5.

[0036] Example 6 The present invention applies the prepared lubricating balls to a ceramic CBN grinding wheel, comprising the following steps: uniformly mixing the prepared lubricating balls into the material of the ceramic CBN grinding wheel; then, through mixing, molding, and high-temperature firing, the ceramic CBN grinding wheel is obtained. The above steps for preparing a ceramic CBN grinding wheel differ from those of the prior art only in that the lubricating balls are uniformly mixed into the remaining material of the ceramic CBN grinding wheel. This embodiment provides a method for preparing a ceramic CBN grinding wheel, comprising the following steps: a. Mixing: Evenly mix the prepared lubricating balls with the CBN material 120 / 140, vitrified bond, and wetting agent, ensuring the balls are fully dispersed among the components to prevent agglomeration. The vitrified bond was purchased from Linyi Niannianwang (New Ceramic Materials) Import and Export Co., Ltd. The wetting agent is a mixture of dextrin powder and water.

[0037] b. Conventional molding: Weigh out the corresponding single weight of 8.5 grams, introduce it into the mold, and use isostatic pressing (uniform pressure in all directions, small density difference, and reduced imbalance). Adjust the pressure to 10 MPa, press to a size thickness of 20 mm, and remove from the mold to dry naturally.

[0038] c. High-temperature firing in a muffle furnace: Place the dried grinding wheel blank into a high-temperature muffle furnace, adjust the firing curve, heat it to 350°C at room temperature for 3 hours, keep it warm for 1.5 hours, heat it to 600°C for 2.5 hours, keep it warm for 1.5 hours, heat it to 800°C, keep it warm for 1 hour, heat it to 880°C, keep it warm for 8-10 hours, and finally cool it to room temperature.

[0039] A performance test was conducted on a vitrified CBN grinding wheel with the lubricating balls prepared in the present invention added thereto.

[0040] Using the same vitrified bond and the same manufacturing process, CBN abrasives were used to create grinding wheels containing different percentages of lubricating balls. Grinding tests on bearing steel GCr15 were conducted using a WTG five-axis tool grinder under the same dressing and grinding conditions. The differences in wheel performance, including wear resistance, sustained sharpness, and workpiece grinding quality, were analyzed. Grinding wheel information and numbers are shown in Table 1.

[0041] Table 1 Grinding wheel number and corresponding lubricating ball ratio

[0042] (1) Finishing process Grinding wheel dressing is divided into two steps: shaping and sharpening. The dressing parameters are shown in Table 2.

[0043] Table 2 Trimming process parameters

[0044] (2) Grinding process A three-phase power meter, AN87500, was used to monitor spindle power during dressing and grinding. A laser displacement sensor, LK-G5001V, was used to precisely measure the thickness of the grinding wheel's abrasive layer loss. A micrometer was used to measure the workpiece's thickness removal. A roughness meter, TIME3230, was used to measure the workpiece's surface roughness Ra. A comparative analysis of the grinding wheel's grinding ratio, grinding power, and surface quality was conducted. See the schematic diagram of the grinding test system for details. Figure 3 The grinding process parameters are shown in Table 3.

[0045] Table 3 Grinding process parameters

[0046] Test results and analysis (1) Grinding ratio The grinding wheel loss volume and workpiece removal volume are calculated from the grinding wheel abrasive layer loss thickness and workpiece removal thickness, and thus the volume ratio is calculated:

[0047] The grinding test was carried out according to the test parameters in Table 2 and Table 3. The grinding ratio results of different grinding wheels under the same test parameters were compared. Figure 4 .

[0048] Depend on Figure 4The grinding ratios of wheels V2 through V4 are superior to those of wheels V1. Comparing the grinding ratios of wheels V2 through V4 reveals a significant change in the grinding ratio with increasing lubricant ball ratios. A higher lubricant ball ratio contributes to a better grinding effect. When the ratio reaches a certain value, the overall cutting capability of the wheel is significantly enhanced, leading to an increase in the grinding ratio. When the lubricant ball ratio is further increased to 25%, the effective abrasive grain count on the wheel surface shows no significant growth trend, and the number of abrasive grains participating in the plowing action during grinding essentially reaches saturation, resulting in a stable grinding ratio. In contrast, the abrasive grains of V5 increase in size with increasing lubricant ball ratios. The abrasive grains that fall off and break during grinding are more effectively lubricated by the graphite, further reducing the grinding ratio.

[0049] (2) Grinding power The power of the spindle motor when the grinding wheel is in a stable grinding state is the grinding power. Figure 5 As shown in the figure, at the end of grinding, the grinding power of the V1 wheel increased rapidly, the workpiece was burned, and the grinding wheel was seriously passivated. The other grinding wheels were in stable grinding state, with good thermal conductivity, high temperature resistance, and good self-sharpening properties. The grinding power was stable at around 590 W.

[0050] (3) Workpiece surface quality After grinding, the workpiece surface profile roundness was measured with Talyrond 400H, and the workpiece surface roughness was measured with TIME3230. The measurement results are as follows: Figure 6 shown.

[0051] Depend on Figure 6 As can be seen, as the proportion of lubricating balls in the grinding wheel increases, the roundness of the ground workpiece surface contour improves. This is because a grinding wheel with more lubricating balls has a stronger material removal capability during grinding. Given a constant feed rate, a grinding wheel with a higher proportion of lubricating balls removes more material when a single abrasive grain removes the same amount of material. Comparing the roundness of workpieces ground with the V2-V5 grinding wheel reveals that the roundness of the workpieces ground with the V1 grinding wheel is significantly better than that of the V5 grinding wheel. The roughness of the workpieces also improves significantly due to the higher number of lubricating balls, which reduces friction during grinding and increases smoothness during grinding. This is because the V2-V5 grinding wheels contain lubricating balls, which have a beneficial effect on roundness / roughness. Furthermore, they have more cutting edges, a higher grinding ratio, and a stronger overall material removal capability. By comparing the surface roughness of the workpiece after grinding with grinding wheels of different lubricating ball ratios and grit sizes, it can be seen that under the same grit conditions, the surface roughness value of the workpiece tends to decrease with the increase of lubricating balls.

[0052] in conclusion In summary, the lubricating ball provided by the application is applied to the ceramic CBN grinding wheel, when the content is 10-18%, the grinding ratio of the grinding wheel is significantly improved, the overall cutting ability of the grinding wheel is enhanced, the cutting and grinding smoothness is increased, the workpiece roughness is reduced, the service life of the grinding wheel is prolonged, and compared with the grinding wheel without adding the lubricating ball, the grinding state is stable, and the workpiece is not burned or scratched.

[0053] The above is the preferred embodiment of the application. It should be pointed out that for ordinary skilled in the art, without departing from the principles of the application, a number of improvements and refinements can be made, which should be considered as the protection scope of the application.

Claims

1. A method for preparing a lubricating ball for manufacturing a ceramic CBN grinding wheel, characterized in that: The following steps are involved: S1, taking a ceramic binder and a liquid phenolic resin and stirring them evenly to obtain a slurry, taking graphite balls and stirring them evenly with the liquid phenolic resin, and coating the liquid phenolic resin on the surface of the graphite balls to obtain wetted graphite balls; S2, immersing the wetted graphite balls in the slurry, evenly wrapping the slurry on the surface of the graphite balls, taking out and filtering to obtain graphite balls coated with a ceramic binder; S3, curing and shaping the graphite ball coated with the ceramic binder in an inert gas atmosphere, and cooling the graphite ball to obtain a lubricating ball.

2. The method for preparing a lubricating ball for manufacturing a vitrified CBN grinding wheel according to claim 1, characterized in that: The weight ratio of the graphite balls to the ceramic binder is 1:2.5-3.

5.

3. The method for preparing a lubricating ball for manufacturing a vitrified CBN grinding wheel according to claim 1, characterized in that: The weight of the graphite balls is a, the weight of the ceramic binder is b, the total weight of the liquid phenolic resin is 6-7% of (a+b), the weight of the liquid phenolic resin in the slurry is 0.8-1.2% of (a+b), and the weight of the liquid phenolic resin in the wetted graphite balls is 5.2-5.8% of (a+b).

4. The method for preparing a lubricating ball for manufacturing a vitrified CBN grinding wheel according to claim 1, characterized in that: The curing conditions are a temperature of 300-350° C. and a time of 2.5-3.5 hours.

5. The method for preparing a lubricating ball for manufacturing a vitrified CBN grinding wheel according to claim 1, characterized in that: The particle size of the graphite balls is the same as that of the ceramic CBN grinding wheel.

6. The method for preparing a lubricating ball for manufacturing a vitrified CBN grinding wheel according to claim 1, characterized in that: The ceramic binder is in the form of powder particles, and the size of the powder particles is ≤35 μm.

7. A lubricating ball produced by the method for producing a lubricating ball for manufacturing a vitrified CBN grinding wheel according to any one of claims 1 to 6.

8. A lubricating ball as claimed in claim 7 applied to a vitrified CBN grinding wheel, characterized in that: The lubricating balls are evenly mixed into the material of the ceramic CBN grinding wheel, and the ceramic CBN grinding wheel is obtained through mixing, molding and high-temperature firing. The lubricating balls account for 10-18% of the total mass of the ceramic CBN grinding wheel raw material.

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