Preparation method of ceramic cBN grinding wheel near-net-shape mixture

Abstract

The application provides a preparation method of a ceramic cBN grinding wheel near-net forming mixture, adopts a linkage method of three-dimensional mixing and dense mixing and melting, obtains a mixture containing abrasive, filler, binder, pore-forming material and various powder materials, and then utilizes a crusher and a ball mill to obtain a crushed material and a powder material, which can be used for injection forming of a micro-size and complex-shape grinding wheel and cold pressing, hot pressing, isostatic pressing forming of a conventional-size and simple-shape grinding wheel, and the sintered grinding wheel has good size retention, the green body has no shrinkage, and the microstructure is uniform and consistent, and belongs to a near-net forming technology of the grinding wheel. The application overcomes the prejudice of the prior art, and different forming methods are no longer limited to corresponding specific powder mixing methods to obtain the flowability and formability of the mixture material special for the forming method, and the obtained ceramic green body belongs to near-net forming, the sintered grinding wheel green body has good size retention, the green body has no shrinkage, and the microstructure is uniform and consistent.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic cBN grinding wheel forming raw material preparation, and particularly relates to a preparation method of a ceramic cBN grinding wheel near-net forming mixture. BACKGROUND

[0002] In conventional mechanical processing, the grinding wheel is regarded as the tooth of mechanical processing, and is commonly used in the mechanical processing of various materials. As a kind of composite material, the grinding wheel mainly contains abrasive, filler, binder, pore-forming material and other powder materials, and the forming method is to process loose powder into a green body with a certain size, shape, density and strength. Traditional forming methods mainly include mold pressing forming, isostatic pressing forming and hot-pressing casting forming. In recent years, with the cross-development of various disciplines, new forming methods are emerging, mainly including injection molding, gel casting molding, 3D printing and other forming methods. Different forming methods have different requirements for the flowability, compressibility and formability of the powder mixture, so the mixing methods used in different forming methods are not uniform. Therefore, it is necessary to develop a new material preparation method to achieve universality for various grinding wheel forming processes. SUMMARY

[0003] The purpose of the present application is to provide a preparation method of a ceramic cBN grinding wheel near-net forming mixture, which can be used for mold pressing forming, hot-pressing casting forming, injection molding and other forming methods. The grinding wheel prepared by using the material has good size retention, no shrinkage of the green body and uniform microstructure. To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0004] A preparation method of a ceramic cBN grinding wheel near-net forming mixture, comprising the following steps: mixing a base material by a three-dimensional mixer to obtain a ceramic base powder, wherein the base material comprises cBN abrasive, filler, binder and pore-forming material, or the base material comprises cBN abrasive, binder and pore-forming material, or the base material comprises cBN abrasive, filler and binder; then mixing the ceramic base powder with a polymer additive by a banbury mixer to obtain a grinding wheel mixture; and crushing and / or ball-milling the grinding wheel mixture to obtain a ceramic cBN grinding wheel near-net forming mixture, which is a grinding wheel mixture suitable for various forming methods.

[0005] The application further discloses a preparation method of a ceramic cBN grinding wheel, which comprises the following steps: forming the ceramic cBN grinding wheel near-net forming mixture to obtain a ceramic cBN grinding wheel; and the forming comprises mold pressing forming, hot-pressing casting forming, injection molding and other forming methods.

[0006] In the present application, the raw materials for preparing the near net shape mixture of the ceramic cBN grinding wheel include cBN abrasive, binder, and filler and / or pore-forming agent; specifically, the near net shape mixture of the ceramic cBN grinding wheel is prepared from cBN abrasive, binder, filler, pore-forming material and high polymer additive, or from cBN abrasive, binder, pore-forming material and high polymer additive, or from cBN abrasive, binder, filler and high polymer additive; the weight of cBN abrasive, filler, binder, pore-forming material and high polymer additive is 100%, the weight of cBN abrasive is 40-70 wt%, the weight of filler is 0-15 wt%, the weight of binder is 12-20 wt%, the weight of pore-forming material is 0-10 wt%, and the rest is high polymer additive, and the filler and pore-forming agent are not both 0; preferably, the weight of cBN abrasive is 50-60 wt%, the weight of filler is 0-10 wt%, the weight of binder is 15-20 wt%, the weight of pore-forming material is 0-10 wt%, and the rest is high polymer additive, and the filler and pore-forming agent are not both 0. When the near net shape mixture of the ceramic cBN grinding wheel is prepared from cBN abrasive, binder, filler, pore-forming material and high polymer additive, the weight of cBN abrasive is 50-60 wt%, the weight of filler is 5-10 wt%, the weight of binder is 15-20 wt%, the weight of pore-forming material is 5-10 wt%, and the rest is high polymer additive; when the near net shape mixture of the ceramic cBN grinding wheel is prepared from cBN abrasive, binder, filler and high polymer additive, the weight of cBN abrasive is 50-60 wt%, the weight of filler is 5-10 wt%, the weight of binder is 15-20 wt%, and the rest is high polymer additive; when the near net shape mixture of the ceramic cBN grinding wheel is prepared from cBN abrasive, binder, filler and high polymer additive, the weight of cBN abrasive is 50-60 wt%, the weight of binder is 15-20 wt%, the weight of pore-forming material is 5-10 wt%, and the rest is high polymer additive.

[0007] In the present application, the binder is composed of silicon dioxide, boron oxide, sodium oxide and zinc oxide; the filler can be alumina, silicon carbide, microcrystalline corundum, etc.; the pore-forming material can be carbon powder, nutshell powder, starch, etc.; in the binder, the weight percentage of each component is as follows: silicon dioxide 65-75%, boron oxide 10-25%, sodium oxide 2-5%, and zinc oxide in the rest; preferably, silicon dioxide 67-73%, boron oxide 20-25%, sodium oxide 3-5%, and zinc oxide in the rest.

[0008] In the application, the polymer auxiliary agent is composed of polystyrene, butyl acrylate, methyl methacrylate resin, paraffin wax and ester wax; the weight percentage of each component is polystyrene 45-60%, butyl acrylate 5-10%, methyl methacrylate resin 20-30%, paraffin wax 1-8% and ester wax the rest; preferably, polystyrene 50-55%, butyl acrylate 7-10%, methyl methacrylate resin 22-27%, paraffin wax 3-7% and ester wax the rest.

[0009] The application discloses a preparation method of a ceramic cBN grinding wheel near-net forming mixture, the ceramic cBN grinding wheel near-net forming mixture prepared by the method and application of the grinding wheel mixture in various forming modes of the cBN grinding wheel. The application overcomes the existing technical prejudice, and different forming modes are no longer limited to corresponding specific powder mixing methods, so that the flowability and formability of the mixture material special for the forming mode are obtained, and the obtained ceramic blank is near-net formed, the size of the sintered grinding wheel blank is good in size retention, the blank has no shrinkage and the microstructure is uniform.

[0010] In the application, the base material is sieved and then mixed in a three-dimensional mixer, the rotating speed of the cylinder is 10-30 r / min, and the mixing time is 30-60 min; the temperature of the internal mixer is 130-170 DEG C, the rotating speed is 15-30 r / min, and the time is 120-200 min.

[0011] In the application, the grinding wheel mixture after the internal mixing is crushed by a jaw crusher, the particle size is distributed in 1-10 mm, the crushed material can be injected by an injection molding machine to obtain a grinding wheel blank, the crushed material is ball milled to obtain a powder material, the particle size is distributed in 100-150 um, and the powder material can be obtained by cold pressing, hot pressing, cold isostatic pressing and the like to obtain a grinding wheel blank.

[0012] Compared with the prior art, the application has the following advantages:

[0013] The present application overcomes the technical prejudice that the mixing method is different for different forming methods, and the different forming methods are no longer limited to the specific powder mixing method, so as to obtain the flowability and formability of the mixture specific to the forming method, and creatively make the mixed material be used for injection molding of small size and complex shape grinding wheel, cold pressing, hot pressing, isostatic pressing and other forming methods of conventional size and simple shape grinding wheel, and has wide application range. The grinding wheel mixture prepared by the method of the present application has stable preparation method, high mixing efficiency, uniform microstructure, long storage time, and the grinding wheel prepared by different forming methods has good size retention after sintering, no shrinkage of the green body, uniform microstructure and higher processing performance than the grinding wheel prepared by the traditional mixing method. The grinding wheel prepared by the present application can be used as an abrasive tool for processing powder metal workpieces, cast iron workpieces and steel workpieces. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The grinding wheel mixture prepared after the internal mixer.

[0015] Figure 2 The small size grinding wheel prepared by injection molding, and different specifications and sizes of grinding wheels are designed in the same mold.

[0016] Figure 3 The microstructure of the grinding wheel green body prepared by the mixing method of the present application.

[0017] Figure 4 The microstructure of the grinding wheel green body prepared by the conventional mixing method.

[0018] Figure 5 The microstructure of the grinding wheel after sintering prepared by the preparation method of the present application.

[0019] Figure 6 The conventional size grinding wheel prepared by mold pressing. DETAILED DESCRIPTION

[0020] The preparation method of the near-net forming mixture of the ceramic cBN grinding wheel disclosed in the application is as follows: the base material is mixed by a three-dimensional mixer to obtain a ceramic base powder, the base material includes cBN abrasive, filler, binder and pore-forming material, or the base material includes cBN abrasive, binder and pore-forming material, or the base material includes cBN abrasive, filler and binder; then, a polymer additive is added and mixed by a banbury mixer to obtain a grinding wheel mixture; subsequently, the grinding wheel mixture can be crushed by a jaw crusher (the particle size distribution of the crushed material is 5-7 mm) and then placed in an injection molding machine to obtain a grinding wheel green body, or the grinding wheel mixture can be crushed by a jaw crusher and then ball milled to obtain a grinding wheel powder, and the grinding wheel powder can be placed in a metal mold and used for cold pressing, hot pressing, cold isostatic pressing and the like to obtain a grinding wheel green body; finally, the grinding wheel green body is degreased and sintered to obtain a ceramic cBN grinding wheel, the size retention of the sintered grinding wheel is good, the green body does not shrink, and the microstructure is uniform and consistent, which belongs to a near-net forming technology of the grinding wheel.

[0021] The process of injection molding is that each raw material in the formula is placed in a barrel of an injection molding machine, the injection temperature is 150-170 DEG C, the screw rotation speed of the injection molding machine is 25-30 r / min, the injection amount is 15-25 g, the pressure maintaining time is 5-10 s, and the injection mold temperature is 75-90 DEG C.

[0022] In the application, the particle size of the cBN abrasive is micron level, for example, 40-100 microns; the particle size of the filler is 50-100 microns; the particle size of the pore-forming agent is 30-100 microns, for example, 50-70 microns; the particle size of the binder is 10-50 microns, for example, 10-20 microns; and the particle size of the polymer additive is 1-50 microns, for example, 5-15 microns. The raw materials are conventional raw materials for preparing grinding wheels in the field.

[0023] The workpiece machining corresponding to the grinding wheel is performed by a customer in the existing conventional supply, the performance characterization of the grinding wheel mixture such as fluidity, pore size, and microstructure (observed by a scanning electron microscope) is a conventional method in the field, the shrinkage rate refers to the size change rate of the grinding wheel before and after sintering, the size change amount refers to the error size between the actual size of the workpiece after machining and the standard size of the workpiece required in the work instruction, and a fluctuation range of the workpiece size, and the unit is microns. The raw materials are conventional raw materials in the field; and the specific preparation operation is a conventional technology. Polystyrene-Mingyuan Plastic Co., Ltd., paraffin-Wo Neng New Material, butyl acrylate, ester wax-Guoyao Reagent, methyl methacrylate resin-Yousheng New Material; polyethylene-Mingyuan Plastic, paraffin-Wo Neng New Material, stearic acid, polyethylene glycol-Guoyao Reagent, phenolic resin-Blue Sky Chemical Co., Ltd.

[0024] Preparation example

[0025] The weight percentage of each component in the binder is 70% of silicon dioxide, 23% of boron oxide, 5% of sodium oxide, and 2% of zinc oxide. The preparation is a conventional method, which is briefly described as follows: after the materials in the formula are uniformly mixed, the following steps are performed in sequence: smelting, quenching, drying, ball milling, and sieving, wherein the smelting temperature is 1400°C, the smelting time is 60 min; the quenching temperature is 35°C, and the time is 30 min; the drying temperature is 120°C, and the time is 6 h; the ball milling time is 2 h, and the sieving mesh size is 320 meshes.

[0026] In the following experiments, the particle size of the binder is 10-20 microns, the particle size of the cBN abrasive is 50-60 microns, the particle size of the filler is 60-70 microns, the particle size of the binder is 10-20 microns, the particle size of the high polymer additive is 5-15 microns, and the particle size of the pore-forming agent is 50-70 microns.

[0027] In the following experiments, the high polymer additive is composed of polystyrene, butyl acrylate, methyl methacrylate resin, paraffin wax, and ester wax; the weight percentage of each component is 55% of polystyrene, 8% of butyl acrylate, 25% of methyl methacrylate resin, 5% of paraffin wax, and 7% of ester wax. According to the conventional method, the polystyrene, butyl acrylate, methyl methacrylate resin, paraffin wax, and ester wax are tumbled and granulated to obtain the high polymer additive. Example One

[0028] 480g of cBN abrasive, 80g of filler SiC, 40g of pore-forming material shell powder, and 120g of binder are weighed, mixed in a three-dimensional mixer after being passed through a 140 / 170 mesh screen, the barrel speed is set to 15 r / min, and the mixing time is set to 45 min. After three-dimensional mixing, ceramic base powder is obtained. Then, 80g of high polymer additive is weighed, and the high polymer additive and the mixed ceramic base powder are placed in an internal mixer, the temperature of the internal mixer is set to 150°C, the speed of the internal mixer is set to 20 r / min, and the mixing time of the internal mixer is set to 150 min. After internal mixing, ceramic internal mixing material is obtained. The ceramic internal mixing material is naturally cooled, broken for 20 min by a jaw crusher to obtain broken material (see Figure 1 ), and the broken material is poured into an injection molding machine to obtain a grinding wheel green body by injection. See Figure 2 , and the grinding wheel has good appearance integrity.

[0029] Comparative Example One

[0030] The formulation of Example One is used, 480g of cBN abrasive, 80g of filler SiC, 40g of pore-forming material shell powder, and 120g of binder are weighed, mixed in a three-dimensional mixer after being passed through a 140 / 170 mesh screen, the barrel speed is set to 15 r / min, and the mixing time is set to 45 min. After three-dimensional mixing, 80g of high polymer additive is added, and the stirring and mixing are continued for 150 min. After being passed through a 140 / 170 mesh screen, the mixture is poured into an injection molding machine to obtain a grinding wheel green body by injection.

[0031] Comparative Example Two

[0032] The high molecular assistant is composed of polyethylene, polyethylene glycol, phenolic resin, paraffin wax, and stearic acid. The weight percentage of each component is 55% polyethylene, 8% polyethylene glycol, 25% phenolic resin, 5% paraffin wax, and 7% stearic acid. The formulation and preparation process of Example One are adopted, and only the high molecular assistant is replaced. The crushed material is put into an injection molding machine to obtain a grinding wheel blank by injection.

[0033] The process of the above injection molding is that each raw material in the formulation is placed in the barrel of the injection molding machine. The injection temperature is 160℃, the screw rotation speed of the injection molding machine is 30r / min, the injection amount is 20g, the pressure holding time is 8s, and the injection mold temperature is 80℃.

[0034] Figure 3 The microstructure of the grinding wheel blank prepared by mixing the materials according to the preparation method of Example One of the present application; Figure 4 The microstructure of the grinding wheel blank prepared by mixing the materials according to the conventional preparation method of Comparative Example One; Figure 5 The microstructure of the grinding wheel after sintering prepared by the preparation method of the present application.

[0035] Comparative Example One

[0036] The formulation of Example One is adopted, and the powder mixture prepared by the existing wet processing mixing method is used to prepare a grinding wheel blank by conventional cold pressing. See Figure 6 The operation method of wet processing mixing is that each raw material of Example One is mixed through a 140 / 170 sieve and then placed in a beaker. 36g of phenolic resin liquid with a viscosity of 6000 mPa·s / 25℃ is added, followed by 80g of alcohol. Then mechanical stirring is performed. The stirring temperature is 30℃, the stirring speed is 50r / min, and the stirring time is 60min. Finally, the mixture is taken out after the alcohol is volatilized after stirring, and the mixture is in a muddy state. After drying at 120℃ for 10min, the cold pressing raw material is obtained by sieving.

[0037] The above grinding wheel blank is defatted and sintered to obtain a grinding wheel. The outer diameter of the grinding wheel is 2.6mm, the inner hole is 1.5mm, and the height is 6mm. The shrinkage rate of the grinding wheel blank of Example One after sintering is 0%, and the shrinkage rate of the comparative example is 15%. The operation method of defatting and sintering is that the grinding wheel blank is placed in a defatting and sintering furnace. From room temperature, it is heated to 200℃ for 300min and then kept for 60min. Then, from 200℃, it is heated to 300℃ for 100min and then kept for 120min. Finally, from 300℃, it is heated to 450℃ for 90min, kept for 120min, heated to 700℃ for 120min, and then kept for 120min. Finally, it is heated to 850℃ for 120min and then kept for 200min. It is naturally cooled.

[0038] The grinding wheel processing performance parameters (processing object is a compressor flange, and the material is powder metallurgy) of the grinding wheel sintered by the green body prepared by the above method are shown in Table 1. It can be seen from the processing results that the grinding wheel prepared by the method has good size retention, the green body has no shrinkage, the microstructure is uniform and consistent, and the processing performance is higher than that of the grinding wheel prepared by the traditional mixing method. It can be seen from Comparative Example 2 that the grinding wheel prepared by the high molecular additive has more excellent processing performance.

[0039] Table 1 Grinding wheel comparison

[0040] Grinding wheel used Processing dressing interval Processing tempo Dimensional variation amount Example 1 100 26-27s -1~+1u Comparative Example 1 80 29-30s 0~+3u Comparative Example 2 70 29-30s 0~+3u Comparative Example 1 60 30-31s -1~+3u

[0041] Comparative Example 3

[0042] The ceramic binder is prepared from raw materials with a weight percentage of 70% of silicon dioxide, 23% of boron oxide, 5% of lithium oxide and 2% of potassium oxide. The formulation and preparation process of Example 1 are adopted, and only the ceramic binder is replaced. The broken material is put into an injection molding machine to obtain a grinding wheel green body by injection. The grinding wheel is obtained by defatting and sintering. The processing and trimming interval is 85.

[0043] Comparative Example 4

[0044] The formulation of Example 1 is adopted, and all the raw materials are mixed together. The mixing parameters are the same as those of Example 1. The ceramic mixed material is naturally cooled, and then broken by a jaw crusher for 20 minutes to obtain a broken material. The broken material is put into an injection molding machine to obtain a grinding wheel green body. After defatting and sintering, defects such as bubbles and holes occur, and the grinding wheel cannot be used.

[0045] Expanded Example 1

[0046] Referring to Example 1, the broken material is ball milled to obtain a powder material with a particle size distribution of 100-120 um. Then, a conventional cold pressing, hot pressing or cold isostatic pressing is used to obtain a grinding wheel green body. The microstructure is uniform, and the storage time is long. The grinding wheel is obtained by defatting and sintering. The grinding wheel has good size retention, the green body has no shrinkage, and the microstructure is uniform and consistent.

[0047] The ceramic cBN grinding wheel used for processing powder metallurgy compressor flanges in existing production has the best application effect, and the trimming interval is 85, the processing rhythm is 29-30 s, and the size change is-1~+2u. Production tests show that the present application creatively enables the mixed material to be used for injection molding of small size and complex shape grinding wheels, and for cold pressing, hot pressing, isostatic pressing and other forming of conventional size and simple shape grinding wheels, and has a wide range of applications. Moreover, the processing performance of the prepared grinding wheel is significantly improved compared with existing industrial products. Example 2

[0048] The 500 g cBN abrasive, the filler WA 100 g, and the binder 200 g are weighed, mixed in a three-dimensional mixer after being passed through a 140 / 170 screen, the barrel rotation speed is set to 25 r / min, and the mixing time is set to 60 min. After three-dimensional mixing, a ceramic base powder is obtained. Then, the polymer additive 200 g is weighed, and the polymer additive and the mixed ceramic base powder are placed in an internal mixer. The internal mixer temperature is set to 170 ℃, the internal mixer rotation speed is set to 20 r / min, and the internal mixing time is set to 120 min. After internal mixing, a ceramic internal mixing material is obtained. After the ceramic internal mixing material is cooled, a jaw crusher is used to crush the material for 20 min to obtain a crushed material. Finally, the crushed material is ball milled at a rotation speed of 500 r / min for 20 min to obtain a ceramic mixed powder material with a particle size of 120 um (D90). According to a conventional cold pressing forming method, the weighed powder material is poured into a mold cavity, and cold pressing forming is performed under the condition that the pressure is set to 30T and the pressure holding time is 10 s. After ejection, a grinding wheel green body is obtained. Finally, the grinding wheel green body is debound and sintered to obtain a target grinding wheel. The outer diameter of the grinding wheel green body obtained in this embodiment is 9.7 mm, the inner diameter is 4 mm, and the height is 10 mm. The shrinkage rate of the sintered grinding wheel is 0.

[0049] Comparative Example Two

[0050] The formulation of Example Two is used, and the operation method of wet processing mixing is as follows: the raw materials are mixed after being passed through a 140 / 170 screen, then placed in a beaker, 36 g of phenolic resin liquid with a viscosity of 6000 mPa·s / 25 ℃ is added, and then 80 g of alcohol is poured in for mechanical stirring mixing. The stirring temperature is 30 ℃, the stirring rotation speed is 50 r / min, and the stirring time is 60 min. Finally, after the alcohol is volatilized after stirring, the mixture is taken out in a mud state, dried at 120 ℃ for 10 min, and then sieved to obtain a cold pressing pressing raw material. According to a conventional cold pressing forming method, a grinding wheel green body is obtained after ejection. Finally, the grinding wheel green body is debound and sintered to obtain a target grinding wheel, and shrinkage exists.

[0051] The operation method of debinding and sintering is as follows: the grinding wheel green body is placed in a debinding and sintering furnace, heated from room temperature to 200 ℃ for 300 min, kept for 60 min, then heated from 200 ℃ to 300 ℃ for 80 min, kept for 120 min, finally heated from 300 ℃ to 450 ℃ for 100 min, kept for 120 min, heated from 450 ℃ to 700 ℃ for 120 min, kept for 120 min, and finally heated from 120 min to 850 ℃, kept for 180 min; and naturally cooled.

[0052] Compared with the grinding wheel obtained by using the wet mixing method of conventional cold pressing forming of Comparative Example Two, the grinding wheel trimming interval is increased from 50 to 80, and the grinding wheel life is increased by 30% when processing the same workpiece. The processing object is a compressor cylinder piece made of cast iron material. Example Three

[0053] Weigh 600g cBN abrasive, 100g pore-forming material shell powder, 200g binder, and place them in a three-dimensional mixer after passing through a 140 / 170 sieve. Set the barrel speed to 30r / min and the mixing time to 30min. After three-dimensional mixing, obtain the ceramic base powder. Then weigh 100g of high molecular additives and place them in the internal mixer with the mixed ceramic base powder. Set the internal mixer temperature to 130℃, the internal mixer speed to 15r / min, and the internal mixing time to 200min. After internal mixing, obtain the ceramic internal mixing material. After cooling, break the ceramic internal mixing material using a jaw crusher for 15min to obtain the broken material. The particle size of the broken material is basically distributed at about 8mm. Finally, ball mill the broken material at a speed of 500r / min for 30min to obtain a ceramic mixed powder with a particle size of 100um (D90). Refer to the conventional hot-pressing casting method. Weigh the powder and place it into the mold cavity. Hot-pressing casting is performed under the conditions of a temperature of 90℃ and a pressure of 60T for 10min. After demolding, obtain the green wheel blank. Finally, the green wheel blank is debound and sintered to obtain the target grinding wheel. The green wheel blank obtained in this embodiment has an outer diameter of 47mm, an inner diameter of 28mm, and a height of 24mm. The shrinkage rate of the sintered grinding wheel is 0.

[0054] Comparative Example Three

[0055] Use the formulation of Example Three. Mix each raw material in the formulation, pass it through a sieve, and place it in a mortar. Add 6wt% of phenolic resin powder based on the total weight, then pour in 15wt% of alcohol, and then perform mortar grinding and mixing. The grinding time is 40min. Finally, after the alcohol is volatilized by physical grinding, the mixture is in a muddy state. Dry the mixture at 120℃ for 45min, then sieve it to obtain the raw material for hot-pressing casting. Refer to the conventional hot-pressing casting method. After demolding, obtain the green wheel blank. Finally, the green wheel blank is debound and sintered to obtain the target grinding wheel. There is shrinkage.

[0056] Compared with the grinding wheel made by the conventional hot-pressing casting mixing method, the grinding wheel dressing interval is increased from 100 to 120, and the grinding wheel life is increased by 20%. The processing object is the inner diameter of the ring of the bearing steel conical cabinet bearing.

[0057] The operation method of debinding and sintering is as follows: place the green wheel blank in the debinding and sintering furnace, heat from room temperature to 200℃ for 280min, keep the temperature for 60min, then heat from 200℃ to 320℃ for 90min, keep the temperature for 120min, finally heat from 320℃ to 460℃ for 100min, keep the temperature for 100min, heat from 460℃ to 700℃ for 120min, keep the temperature for 100min, and finally heat from 700℃ to 850℃ for 120min, keep the temperature for 200min, and then naturally cool.

[0058] The preparation method of the near-net forming mixture of the ceramic cBN grinding wheel comprises the following steps: mixing cBN abrasive, filler, binder and pore-forming material through a three-dimensional mixer to obtain ceramic base powder; then adding a polymer additive and mixing through a banbury mixer to obtain a grinding wheel mixture; and finally crushing and ball milling to obtain a grinding wheel mixture suitable for various forming methods. Production tests show that the present application can be used for injection molding of small-size and complex-shape grinding wheels, and can also be used for cold pressing, hot pressing, isostatic pressing and other forming methods of conventional-size and simple-shape grinding wheels, and has a wide range of applications. Moreover, the machining performance of the prepared grinding wheel is significantly improved compared with existing industrial products.

Claims

1. A method for preparing a near-net-shape ceramic cBN grinding wheel mixture, comprising the following steps: mixing a base material using a three-dimensional mixer to obtain a ceramic base powder, wherein the base material includes cBN abrasive, filler, binder, and pore-forming material, or the base material includes cBN abrasive, binder, and pore-forming material, or the base material includes cBN abrasive, filler, and binder; then mixing the ceramic base powder with a polymeric additive using an internal mixing and refining process to obtain a grinding wheel mixture; the grinding wheel mixture is then crushed and / or ball-milled to obtain a near-net-shape ceramic cBN grinding wheel mixture, which is a grinding wheel mixture applicable to various forming methods; wherein the weight sum of cBN abrasive, filler, binder, pore-forming material, and polymeric additive is 100%, the weight of cBN abrasive is 40-70 wt%, the weight of filler is 0-15 wt%, and the weight of binder is... The weight is 12-20 wt%, the weight of the pore-forming material is 0-10 wt%, and the balance is polymeric additives; the filler and pore-forming agent are not the same and the weight is 0. The binder includes silicon dioxide, boron oxide, sodium oxide, and zinc oxide. The filler includes one or more of alumina, silicon carbide, and microcrystalline corundum. The pore-forming material is one or more of carbon powder, nutshell powder, and starch. The polymeric additives include one or more of polystyrene, butyl acrylate, methacrylic resin, paraffin wax, and ester wax. In the binder, the weight percentage of each component is: silicon dioxide 65%-75%, boron oxide 10-25%, sodium oxide 2-5%, and zinc oxide balance. In the polymeric additives, the weight percentage of each component is: polystyrene 45-60%, butyl acrylate 5-10%, methacrylic resin 20-30%, paraffin wax 1%-8%, and ester wax balance.

2. The method for preparing the near-net-shape mixture of ceramic cBN grinding wheels according to claim 1, characterized in that, After sieving the base material, place it in a three-dimensional mixer for mixing. The cylinder speed is 10-30 r / min, and the mixing time is 30-60 min. The internal mixing temperature is 130-170℃, the speed is 15-30 r / min, and the time is 120-200 min.

3. The near-net-shape ceramic cBN grinding wheel mixture prepared by the method for preparing near-net-shape ceramic cBN grinding wheel mixture according to claim 1.

4. A method for preparing a ceramic cBN grinding wheel, wherein the near-net-shape mixture of ceramic cBN grinding wheel as described in claim 3 is formed to obtain a ceramic cBN grinding wheel.

5. The method for preparing the ceramic cBN grinding wheel according to claim 4, characterized in that, The molding process includes compression molding, hot die casting, or injection molding.

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