In recent years, the performance of machine tool spindles has been further developed in the direction of high speed, high precision and high rigidity. While meeting these requirements, it must also be conducive to environmental protection and pay attention to environmental issues such as global warming. Special features of the design Mr. Yu Wei: NSK's bearing design is based on tribology and relies on the four core technologies of tribology (analytical, evaluation, lubrication and material). This is especially true for the design of machine tool spindle bearings. First, NSK has developed long-life, high-performance bearing materials using its latest technology. Secondly, for the design of rolling elements, we have developed ceramic materials with superior performance in high-speed and ultra-high-speed environments, effectively achieving the ultra-high-speed and ultra-high-precision rotation requirements that metal rolling elements cannot achieve. Has won the praise of the majority of users. In addition, NSK has developed a rolling element-guided resin cage with a unique structural shape, which has a short grease running-in time, stable temperature rise, low friction and low noise, especially in grease-lubricated conditions. For precision cylindrical roller bearings, ultra-high performance PPS and PEEK resin materials are used, which have superior high speed and heat resistance. Mr. Chen Shizhen: The radial error of the spindle bearing, the end face runout, the inconsistent rolling element diameter and other shape errors will seriously affect the accuracy of the spindle system and its machining parts. Therefore, the bearing accuracy on the precision machine tool spindle should be P5 and above. For the spindle support of high-speed, high-precision machine tools such as CNC machine tools and machining centers, P4 and above super-precision bearings are required. The high-speed adaptability of the spindle bearings is also particularly important, especially in order to meet the ever-increasing processing speed, the development and continuous improvement of high-speed spindles including electric spindles, and the high-speed adaptability of spindle bearings is becoming higher and higher. If the high-speed adaptability of the bearing is not good, the temperature rise of the spindle system will be very serious, and even burn out. Mr. Ye Jun: As a key basic component, the machine tool spindle bearing is the cornerstone for the machine tool machining accuracy index. With the development of modern machine tools in the direction of high precision, high speed and high reliability, higher requirements are placed on the spindle bearings. For example, in traditional machinery or general machinery, the speed is mainly in the hundreds to thousands of revolutions per minute, while in modern high-speed machining machines, the spindle speed is required to reach tens of thousands to tens of thousands of revolutions per minute. In the bearing industry, dmN value is used to express high-speed performance. It is the product of diameter and speed. The index of machine tool spindle is generally less than 2 million, and the highest is 4 million. The requirement is very high. Therefore, new requirements are put forward for the design of bearings. Taking angular contact ball bearings as an example, it is necessary to analyze the requirements of the spindle from the aspects of material selection, structure design, guiding method, lubrication mode design and groove curvature coefficient selection. ,the study. Research on materials Mr. Ye Jun: Due to the high precision, high speed and high reliability requirements of the spindle bearings of machine tools, there are some special requirements on the materials. The ferrule materials are mostly made of high quality refined steel, and there are special special steels abroad. The cage material is copper, plastic, and special self-lubricating material. The rolling elements are bearing steel and ceramic materials. As a new material, the application of ceramic materials in rolling bearings opens up a new world of bearing materials. The application of ceramic materials has broken through many application limits of traditional steel bearings, such as high speed, wear resistance, insulation and temperature resistance. The commonly used silicon nitride ceramics only have more than 1/3 of the steel, so the stress level of the rolling element to the ferrule caused by the high speed is greatly reduced, and the limit speed of the bearing of the same size is greatly improved; the hardness of the silicon nitride ceramic is up to 1500 HV. It is double the bearing steel, and the high temperature resistance up to 1200 °C is 6 times that of the bearing steel. These undoubtedly expand the range of use of traditional steel bearings. Therefore, it can be said that the application of ceramic materials is a revolution in rolling bearing materials, and ceramic material bearings are the most promising new material bearings for the 21st century. Mr. Chen Shizhen: For general machine tool spindles, there are no special requirements for the material of the spindle bearings. However, with the development of the main axis of the CNC machine tool, the running speed of the spindle bearing is getting higher and higher, and the material requirements are getting higher and higher. At present, ceramic materials (mainly referred to as Si3N4 engineering ceramics) have become an ideal material for manufacturing high-speed precision bearings. Compared with bearing steel, ceramic materials have the following advantages: 1) low density. The weight and speed of the bearing can be achieved. 2) High rigidity. The elastic deformation after the force is small, and the rigidity of the relative load is high, which can increase the rigidity by 15% to 20%, thereby reducing the vibration of the machine tool. 3) The coefficient of thermal expansion is small. The dimensional change of the ceramic bearing with temperature changes is small, and the generated thermal preload is low, thereby avoiding excessive heat accumulation and fatigue peeling failure. 4) The coefficient of friction is small. The heat generated during operation is small, which greatly reduces the stress of materials and lubricants in the hybrid bearing. Ceramic bearings have been used more and more widely, but due to the difficult processing of ceramic materials, precision ceramic bearings are mostly hybrid ceramic ball bearings whose rolling elements are ceramics and inner jacket rings are still made of bearing steel. Mr. Yu Wei: With the development of the main axis of CNC machine tools, the requirements for high speed, high stiffness, low temperature rise and long life are proposed for the spindle bearings. Ceramic materials (mainly referred to as Si3N4 engineering ceramics) are ideal materials for manufacturing high-speed precision bearings because of their low density, high modulus of elasticity, low thermal expansion coefficient, wear resistance, high temperature resistance and corrosion resistance. Specifically, compared with the steel ball bearing, firstly, the weight of the ceramic is 40% lighter than that of the steel ball, so the centrifugal force acting on the rolling element has little influence and low heat generation; secondly, the linear expansion coefficient is low, and the bearing temperature rises at high speed rotation. The pre-tightening force is lower than that of the steel ball, and the heat is low; in addition, the wear resistance is stronger and the rigidity is higher, and the cutting process with higher precision can be realized. In addition to ceramic rolling elements, NSK has developed long-life, high-performance spindle bearing materials by studying the long-life technology. They are: durable SHX material in ultra-high-speed rotary environment, high-reliability EP steel under high load environment, Z steel with long life in various general environments. Extremely high guiding accuracy and speed Mr. Chen Shizhen: For the technical requirements of the spindle bearings to meet the extremely high guiding precision and speed, FAG's solutions are mainly reflected in the selection of new materials, product design optimization, guarantee and improvement of machining quality. Through continuous theoretical analysis, testing and application feedback, the internal parameters of the spindle bearings are continually optimized, including the design of TX cages. The contact point of the cage is extremely important for increasing the speed. This TX cage design and lubricant flow reduce the temperature rise of the FAG TX spindle bearing by 10% at high speeds. At the same time, this new bearing series is at the same boundary. Under conditions, the speed can be increased by up to 10%. In addition, due to the large temperature field gradient in the electric spindle, the temperatures of the two bearings are different, resulting in uneven bearing and axial bearing of each bearing during operation. These uneven loads affect the rigidity of the bearing and the bearings arranged in series. The service life of the group. The FAG's optional series of bearing sets for the electric spindle greatly reduces these problems. Mr. Ye Jun: Axis Research Technology can provide a complete solution for the requirements of machine tool spindle bearings P4 ~ P2. In order to meet the high precision and high speed of the spindle bearings, the company has developed high-speed plastic safety frame materials, ceramic material rolling elements, high-precision bearing assembly technology and universal matching technology. The precision machine tool spindle bearings developed by the company have won national high-tech products. "Machine spindle bearing manufacturing technology and application technology" won the provincial and ministerial level awards, "Research on high-speed bearing plastic cage materials" won the national award. Solution to wear and heat problems Mr. Yu Wei: Specifically, NSK has developed high-performance steel with higher mechanical strength and long life and ceramic rolling elements with high precision and high-speed performance, which effectively solves the problem of wear and heat during bearing operation. In addition, our improvement on the structure and materials of the cage makes the cage have less influence on the deterioration of grease, more lubrication and better heat resistance. At the same time, in order to effectively ensure the lubrication conditions during bearing operation, and to minimize or even prevent the intrusion of dust and solve the problem of wear and heat, NSK continuously improves and designs the bearing and lubrication methods, and achieves the first oil and gas lubrication. The method has gradually been adopted by a large number of users and has been widely recognized. In recent years, with the advent of the era of environmental protection, NSK has developed a grease replenishment system for high-speed spindles, which intermittently replenishes a small amount of grease to high-speed bearings while using the best-shaped spacers. The grease is discharged into the storage tank provided in the bearing housing, which is the first in the world to achieve grease lubrication in the high-speed field, and also achieve long life and low temperature rise. Automobile Parts Mould,Door Panel Injection Mould,Door Panel Plastic Injection Mold,Automobile Door Plastic Injection Moulds Taizhou ANO MOULD CO.,LTD , https://www.ainomould.com