Large-diameter ceramic grinding wheel for crankshaft and preparation method thereof
By optimizing the composition and preparation process of abrasives and binders, the problems of cracking and clogging in the firing and grinding process of large-diameter ceramic grinding wheels were solved, achieving high strength, wear resistance and high efficiency grinding effect, and ensuring the surface quality and precision of workpieces.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BAIGE ABRASIVES CO LTD
- Filing Date
- 2024-06-26
- Publication Date
- 2026-07-31
AI Technical Summary
Large-diameter ceramic grinding wheels are prone to cracking during the firing process, resulting in a high scrap rate. They are also prone to clogging during grinding, leading to low efficiency, burns on the workpiece surface, and poor precision.
The abrasive consists of 60%-90% abrasive and 10%-20% binder. The abrasive is composed of 80# ceramic corundum, 60# packed abrasive, 80# low-sodium high-purity corundum, and 80# white corundum. The binder is composed of clay powder, cryolite, zirconium silicate, and feldspar powder. The ceramic grinding wheel is prepared through a specific mixing, pressing, and sintering process to increase the thermal conductivity of cryolite and the mechanical strength of zirconium silicate in order to improve the performance of the binder.
It effectively reduces the scrap rate of ceramic grinding wheels, improves the strength and wear resistance of grinding wheels, ensures that they are not easily clogged during grinding, improves the surface quality and precision of workpieces, reduces the number of dressing operations, and improves production efficiency.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of grinding wheel manufacturing technology, and in particular to a large-diameter ceramic grinding wheel for crankshafts and its preparation method. Background Technology
[0002] With the rapid development of the national economy, marine engines and industrial compressors are widely used in industry, and their power requirements are becoming increasingly larger. Whether it's a giant marine engine or a large gas compressor, these two types of products share a common feature: the conversion of energy must be accomplished through the core component of the machine—the rotation of a large crankshaft. Crankshafts are mostly made of forged steel, alloy steel, etc. The harsh working environment of large crankshafts necessitates high material strength, high surface hardness, and high surface precision.
[0003] Large-diameter (>915mm) crankshaft-specific ceramic grinding wheels are mainly used for grinding the connecting rod journals and main journals of crankshafts. However, the following problems still exist in the firing process of large-diameter (>915mm) crankshaft-specific ceramic grinding wheels:
[0004] During the firing process, changes in temperature gradients can easily lead to firing cracks, resulting in a high scrap rate. When heating or cooling, the presence of temperature gradients causes different parts of the material to have different temperatures and corresponding degrees of thermal expansion or contraction. Parts closer to the heat source will expand first, while parts farther from the heat source will expand later. This means that there are significant temperature differences between different parts of the same workpiece, resulting in asynchronous shrinkage rates in different parts. This will generate thermal stress inside the material. If this thermal stress exceeds the tensile strength of the material, it will lead to the formation of cracks. Moreover, the grinding wheel will have significant volume changes (shrinkage), especially in large-sized or complex-shaped workpieces, where cracks are more likely to occur.
[0005] 2. Ceramic grinding wheels are prone to clogging during grinding. When used on large crankshafts with high material strength, high surface hardness, and high surface precision requirements, the holes on the grinding wheel become clogged, resulting in low heat dissipation efficiency. This leads to defects such as burns and poor precision on the surface of the workpiece after grinding, thereby increasing the number of times the grinding wheel needs to be dressed, which indirectly leads to extended production time and reduced work efficiency.
[0006] To solve the above problems, it is necessary to develop a large-diameter ceramic grinding wheel for crankshafts and its preparation method, which can solve the problems of ceramic grinding wheels being prone to sintering cracks, resulting in a high scrap rate, easy clogging during grinding, low efficiency, and workpiece surface burns and out-of-tolerance precision after grinding. Summary of the Invention
[0007] In view of the above situation, in order to overcome the shortcomings of the existing technology;
[0008] This invention provides a large-diameter ceramic grinding wheel for crankshafts and its preparation method, comprising, by mass percentage, 60%-90% abrasive and 10%-20% binder, wherein:
[0009] The abrasive consists of 22%-50% 80# ceramic corundum, 11%-33% 60# deposited abrasive, 11%-16% 80# low-sodium high-purity corundum, and 33-66% 80# white corundum.
[0010] The binder consists of 20%-30% clay powder, 30%-40% cryolite, 10%-20% zirconium silicate, 1%-5% zirconium oxide, and 20%-40% feldspar powder.
[0011] Preferably, the preparation method of the binder is as follows: the raw materials of each component of the binder are placed in a ball mill and ball-milled for 4-5 hours, and then sieved through a 100-mesh sieve to obtain the finished binder.
[0012] Preferably, the chemical properties of the calcite powder in the binder are as follows: silicon dioxide 68%-73%, aluminum oxide 16%-20%, ferric oxide <0.3%, calcium oxide <0.5%, magnesium oxide <0.5%, potassium oxide >9.0%, sodium oxide <2.5%, loss on ignition <0.5%, and refractoriness 1285-1300℃.
[0013] Preferably, the preparation method of the abrasive is as follows: 400# white corundum and abrasive binder are mixed in a ratio of 10:1, and after mixing, the mixture is pressed into shape under a pressure of 10MPa, then sintered at 1300℃ for 48 hours, and finally crushed into 60# particle size to obtain the finished abrasive.
[0014] Preferably, the abrasive binder in the preparation of the abrasive is composed of 50% 400# clay and 50% 400# feldspar.
[0015] Preferably, the particle size of each component of the binder is 600 mesh.
[0016] A method for preparing a ceramic grinding wheel, used to produce a large-diameter ceramic grinding wheel for crankshafts, the method comprising the following steps:
[0017] S1. Mixing: Mix the above abrasive with the wetting agent evenly, and stir for 10-15 minutes to obtain the mixed abrasive;
[0018] S2. Curing: Mix the binder, adhesive and abrasive evenly for 10-15 minutes. After mixing, pass the mixture through a No. 12 sieve and cure for 25-35 hours.
[0019] S3. Molding: Place the material after curing into a molding mold, press it into shape at 6-9MPa, and then dry it at 60℃ for 140-160 hours.
[0020] S4. Firing: The dried material is sintered using a car kiln process at a temperature of 1000℃~1200℃, with a heating rate of 5-10℃ / min. After sintering, the material is held at the temperature for 40-50 hours and then cooled to room temperature to obtain the finished grinding wheel.
[0021] Preferably, in step S1, the mass of the wetting agent is 25‰-30‰ of the total weight of the abrasive and binder, and the wetting agent is a dextrin solution with a concentration of 1.05-1.08 g / cm3.
[0022] Preferably, in step S2, the mass of the adhesive is 20‰-25‰ of the total weight of the abrasive and the binder, and the adhesive is 400-mesh dextrin powder.
[0023] Compared with the prior art, the present invention provides a large-diameter ceramic grinding wheel for crankshafts and its preparation method, which has the following beneficial effects:
[0024] 1. This invention adds a certain amount of zirconium silicate and cryolite to the binder. Cryolite has good thermal conductivity and a low melting point, which can quickly transfer heat to the interior of the grinding wheel during the firing process, avoiding thermal stress in the material and reducing cracks or deformations caused by overheating of the workpiece. It can also enhance the bonding force between the binder and abrasive particles, making the grinding wheel structure more compact and improving the overall strength and wear resistance of the grinding wheel. At the same time, cryolite promotes the melting and fusion of ceramic particles at lower temperatures by lowering the melting point, further improving the microstructure and properties of the ceramic. Zirconium silicate has high hardness, and its addition to the ceramic grinding wheel binder can improve the overall mechanical strength and wear resistance of the grinding wheel. Zirconium silicate has excellent high-temperature resistance, and can maintain a stable physical state even in the high-temperature environment generated during grinding, preventing premature failure or decomposition of the binder. After co-firing with ceramic raw materials, zirconium silicate can exchange ions in the crystal lattice to form a stable crystal phase, thereby strengthening the mechanical properties and durability of the ceramic, improving the chemical and thermal stability of the binder, and effectively reducing the scrap rate.
[0025] 2. This invention achieves excellent self-sharpening properties and lifespan by using a specific ratio of deposited abrasive and ceramic corundum. During grinding, microparticles slowly detach, exposing new abrasive grains to participate in the work. Furthermore, the low surface roughness of the deposited abrasive during the firing process allows for better adhesion, contributing to improved overall quality and performance of the ceramic grinding wheel. Meanwhile, the ceramic corundum abrasive enhances the sharpness of the grinding wheel while significantly improving its shape retention. This ensures that the grinding object maintains consistent precision, efficiency, and stability, solving problems such as easy clogging, low efficiency, and surface burns and out-of-tolerance precision of the workpiece after grinding.
[0026] 3. This invention adds low-sodium high-purity corundum and zirconium oxide as auxiliary raw materials. Zirconium oxide with a low coefficient of expansion can improve the sharpness of the grinding wheel and also improve the stability of the binder. Low-sodium high-purity corundum has the characteristics of "low sodium" and "high purity". The reduction of sodium content helps to improve the high temperature resistance and chemical stability of the material, and reduces the likelihood of sodium reacting with other substances at high temperatures, which would lead to structural deterioration and performance degradation of the abrasive in high-temperature working environments. At the same time, high purity can reduce contamination on the surface of the workpiece being processed, ensuring higher surface quality and smoothness of the processed workpiece.
[0027] The novel abrasive ceramic grinding wheel for large-diameter (>915mm) crankshafts developed in this invention uses a new type of abrasive. Among them, the corundum abrasive has more cutting edges per particle compared with ordinary white corundum abrasive, which significantly improves the sharpness of the grinding wheel. The addition of low-sodium high-purity corundum and ceramic corundum also significantly improves the sharpness of the grinding wheel, as well as its strength and shape retention. Detailed Implementation
[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1
[0029] A large-diameter ceramic grinding wheel for crankshafts, comprising 88% abrasive and 12% bonding agent by mass percentage, wherein:
[0030] The abrasive consists of 34% 80# ceramic corundum, 17% 60# deposited abrasive, 17% 80# low-sodium high-purity corundum, and 32% 80# white corundum.
[0031] The binder consists of 23% clay powder, 37% cryolite, 13% zirconium silicate, 2% zirconium oxide and 25% feldspar powder;
[0032] The wetting agent is 27‰ of the total weight of the abrasive and binder, and the wetting agent is a dextrin solution with a concentration of 1.06 g / cm3;
[0033] The mass of the binder is 22‰ of the total weight of the abrasive and the binder, and the binder is 400-mesh dextrin powder.
[0034] The preparation method of the binder is as follows: place the raw materials of each component of the binder in a ball mill and ball mill for 4.5 hours, and then sieve through a 100-mesh sieve to obtain the finished binder.
[0035] A method for preparing a ceramic grinding wheel includes the following steps:
[0036] S1. Mixing: Mix the above abrasive with the wetting agent evenly, and stir for 10-15 minutes to obtain the mixed abrasive;
[0037] S2. Curing: Mix the binder, adhesive and abrasive evenly for 10-15 minutes. After mixing, pass the mixture through a No. 12 sieve and cure for 25-35 hours.
[0038] S3. Molding: Place the material after curing into a molding mold, press it into shape at 6-9MPa, and then dry it at 60℃ for 140-160 hours.
[0039] S4. Firing: The dried material is sintered using a car kiln process at a temperature of 1000℃~1200℃, with a heating rate of 5-10℃ / min. After sintering, the material is held at the temperature for 40-50 hours and then cooled to room temperature to obtain the finished grinding wheel. Example 2
[0040] A large-diameter ceramic grinding wheel for crankshafts, comprising 91% abrasive and 9% bonding agent by mass percentage, wherein:
[0041] The abrasive consists of 32% 80# ceramic corundum, 16% 60# deposited abrasive, 16% 80# low-sodium high-purity corundum, and 36% 80# white corundum.
[0042] The difference between Example 2 and Example 1 is that the ratio of abrasive and binder in the ceramic grinding wheel was changed, and the abrasive ratio was also changed accordingly. The other components and steps are the same as in Example 1. Example 3
[0043] A large-diameter ceramic grinding wheel for crankshafts, comprising 86% abrasive and 14% bonding agent by mass percentage, wherein:
[0044] The abrasive consists of 34% 80# ceramic corundum, 17% 60# deposited abrasive, 17% 80# low-sodium high-purity corundum, and 32% 80# white corundum.
[0045] The wetting agent is 29‰ of the total weight of the abrasive and binder, and the wetting agent is a dextrin solution with a concentration of 1.06 g / cm3;
[0046] The difference between Example 3 and Example 1 is that the proportion of abrasive and binder in the ceramic grinding wheel was changed, the abrasive ratio was also changed accordingly, and the quality of the wetting agent was also changed. The remaining component ratios and steps are the same as in Example 1.
[0047] Comparative example:
[0048] A ceramic grinding wheel, by mass percentage, comprises 88% abrasive and 12% binder, wherein:
[0049] The abrasive is 80# white corundum;
[0050] The binder consists of 35% clay powder and 65% feldspar powder.
[0051] The difference between the comparative example and Example 1 is that the abrasive composition was replaced with conventional white corundum, and the cryolite, zirconium silicate and zirconium oxide in the binder were removed and replaced with an equal mass of clay powder and feldspar powder. The remaining steps remained unchanged from Example 1.
[0052] The following is a comparative analysis of Example 1, Example 2, Example 3, and the comparative example:
[0053] Under the same parameters, the hardness, durability, workpiece roughness after grinding, and surface defects after grinding of the grinding wheel were compared.
[0054] Table 1 Performance Comparison
[0055]
[0056] As shown in Table 1, the parameters of the comparative examples using traditional abrasives and binders are all worse than those of Examples 1, 2 and 3. The durability is 0.2 workpieces, which means that the grinding wheel needs to be dressed multiple times to complete one workpiece, and the surface after grinding has slight scratches. At the same time, the scrap rate is high.
[0057] Example 2 has the highest hardness. Because of its high hardness, the abrasive grains are more difficult to remove from the grinding wheel after they become passivated, resulting in poor surface roughness of the workpiece after grinding. In addition, slight scratches and sand shedding appear on the surface. The durability is only enough to process 0.5 workpieces. Even so, the grinding wheel needs to be dressed at least once during the processing of one part.
[0058] Example 3 showed the best surface roughness after workpiece grinding, and the durability was also improved from 0.5 workpieces to 0.6 workpieces. However, the hardness was lower than that of Example 1, Example 2 and the comparative example. Due to the low hardness, the dulled abrasive grains fell off quickly, exposing new sharp abrasive grains. During grinding, more material was removed per unit time, resulting in local heat concentration. The heat could not be dissipated in time, which caused slight burns on the workpiece surface.
[0059] The parameters of Example 1 are relatively balanced. Although the surface roughness of the workpiece after grinding is not as good as that of Example 3, it is worse than that of Example 2 and the comparative example. Moreover, there are no defects on the surface of the workpiece after grinding. At the same time, the durability is 1 workpiece, which means that the grinding wheel does not need to be dressed during the processing of a single workpiece, which can save the processing time of the workpiece. The hardness is also better than that of the comparative example and Example 3.
[0060] Therefore, it can be seen that using this formula to make a large-diameter ceramic grinding wheel for crankshafts can increase the hardness, durability and improve the surface roughness of the workpiece after grinding, changing from 0.2 workpieces to 1 workpiece. The surface of the machined workpiece is free of defects, and no dressing of the grinding wheel is required during the machining process. At the same time, it can reduce the scrap rate in the grinding wheel manufacturing process.
Claims
1. A large-diameter ceramic grinding wheel for crankshafts, characterized in that, Based on mass percentage, it consists of 60%-90% abrasive and 10%-20% binder, wherein: The abrasive consists of 22%-50% 80# ceramic corundum, 11%-33% 60# deposited abrasive, 11%-16% 80# low-sodium high-purity corundum, and 33-66% 80# white corundum. The binder consists of 20%-30% clay powder, 30%-40% cryolite, 10%-20% zirconium silicate, 1%-5% zirconium oxide and 20%-40% feldspar powder. The chemical properties of the long white stone powder in the binder are as follows: silicon dioxide 68%-73%, aluminum oxide 16%-20%, ferric oxide <0.3%, calcium oxide <0.5%, magnesium oxide <0.5%, potassium oxide >9.0%, sodium oxide <2.5%, loss on ignition <0.5%, and refractoriness 1285-1300℃; The preparation method of the abrasive is as follows: 400# white corundum and abrasive binder are mixed in a ratio of 10:1, and after mixing, they are pressed into shape under a pressure of 10MPa, then sintered at 1300℃ for 48 hours, and finally crushed into 60# particle size to obtain the finished abrasive. The abrasive binder used in the preparation of the abrasive is composed of 50% 400# clay and 50% 400# feldspar.
2. The large-diameter ceramic grinding wheel for a crankshaft according to claim 1, characterized by The preparation method of the binder is as follows: place the raw materials of each component of the binder in a ball mill and ball mill for 4-5 hours, and then sieve through a 100-mesh sieve to obtain the finished binder.
3. The large diameter ceramic grinding wheel for crankshaft according to claim 1, wherein The particle size of each component of the binder is 600 mesh.
4. A method for producing a large-diameter ceramic grinding wheel for a crankshaft according to any one of claims 1 to 3, characterized by, The method for preparing the ceramic grinding wheel includes the following steps: S1. Mixing: Mix the abrasive and wetting agent evenly for 10-15 minutes to obtain the mixed abrasive. S2. Curing: Mix the binder, adhesive and abrasive evenly for 10-15 minutes. After mixing, pass the mixture through a No. 12 sieve and cure for 25-35 hours. S3. Molding: Place the material after curing into a molding mold, press it into shape at 6-9MPa, and then dry it at 60℃ for 140-160 hours. S4. Firing: The dried material is sintered using a car kiln process at a temperature of 1000℃~1200℃, with a heating rate of 5-10℃ / min. After sintering, the material is held at the temperature for 40-50 hours and then cooled to room temperature to obtain the finished grinding wheel.
5. The method for preparing a ceramic grinding wheel according to claim 4, characterized in that, In step S1, the mass of the wetting agent is 25‰-30‰ of the total weight of the abrasive and binder, and the wetting agent is a dextrin solution with a concentration of 1.05-1.08 g / cm3.
6. The method of claim 4, wherein the ceramic bond is formed by mixing the ceramic bond powder with a solvent and a dispersant, and then spray-drying the mixture. In step S2, the mass of the adhesive is 20‰-25‰ of the total weight of the abrasive and the binder, and the adhesive is 400-mesh dextrin powder.