Papers by Keyword: Ceramic Bearing

Abstract: One important demand on spindle systems in modern machine tools is to realize higher rotational speed in order to increase the machining efficiency. So, the low rotational inertia and high fundamental natural frequency are indispensable. Because of advanced ceramics' extraordinary physical properties such as high hardness, low thermal expansion, light weight, abrasion resistant and good chemical and thermal stability, it accommodates very well the high-speed and precision requirements of machine tool spindles. In this study, a high-speed ceramic spindle system equipped with high-performance structural ceramic shaft and fully-ceramic ball bearings was designed and developed. The high-speed ceramic motorized spindle prototype was assembled with high precision successfully, and its performance test and analysis were finished. The test results show that ceramic motorized spindle can reduce the high-speed rotational centrifugal force and inertia force and increase the stiffness and rotation accuracy of spindle-bearing system greatly.

Abstract: Recently, hybrid ceramic bearings and oil/air lubrication have been used more and more on high speed spindles. However, applying an appropriate lubrication and the hybrid bearings can’t be overemphasized, and the oil/air supply with inadequate parameters is undesirable. In this study, a high speed ceramic spindle equipped with HIPSN (Hot Isostatically Pressed Silicon Nitride) full-ceramic ball bearing and Y-TZP (Yttria partially stabilized Tetragonal Zirconia Polycrystal) ceramic spindle shaft was designed for higher speed, stiffness, precision and longer operating life. Furthermore, the performance of a high-speed ceramic motorized spindle under different lubrication parameters was investigated. The optimum lubrication conditions that create the smallest temperature increase were obtained by the applying of the Taguchi method. The results show that oil volume per lubrication cycle, interval time per lubrication cycle and air pressure are three pacing factors that affect the temperature increase most significantly in ceramic motorized spindle with oil/air lubrication.

Abstract: This paper presents a high-speed high-precision spindle system with hybrid ceramic bearing, along with its lubricant design and numerical calculation method. A green and viscosity controllable water based fluid as lubricant of the spindle was designed. Viscosities as a function of temperature were tested. Subsequently, numerical calculation was used to deduce a serious of bearing performances. Based on the results rate of the permeation of porous restrictor, some bearing structure parameters and relative optimum lubricant viscosity were determined. The results of thermal elastohydrodynamic simulation and rotor dynamic analysis indicate that the design of the hybrid ceramic bearing meets security and performance specifications. Finally the structure arrangement of the spindle system was finished.

Abstract: This paper deals with the development of a high-efficiency and precision grinding technology for producing HIPSN ceramic bearing races. A new high-speed CNC grinding machine has been developed, which is equipped with a high-speed ceramic spindle with a built-in motor. Extensive experiments have been performed with this new machine to investigate the influence of various process parameters such as wheel speed, work speed, depth of cut, and wheel grit size on material removal rate, surface finish, grinding forces, and so on. The results of these investigations are presented in this paper. With the application of this technology, a low cost production of ceramic bearings race was realized with the most optimized process parameter.

Abstract: In resent years, ceramic balls have been applied into precision bearings and other parts far and wide because of its advantages in light weight, high hardness, abrasive resistance, high-temperature resistance, corrosion resistance, little heat expansion coefficient and so on. The high-precision ceramic balls are machined by lapping usually, and the method of lapping has an important influence on the machining precision and efficiency of ceramic balls. In order to improve the precision and efficiency of ceramic ball machining, in the paper, a new cone lapping method is researched by the lapping experiment. The research result shows that the cone method is the optimal lapping method with high precision, high efficiency and the very simple machine. Furthermore, the mechanics characteristic of the cone lapping method have been analyzed and summarized, which will provide the basic principle and theoretical basis for the choice of primary geometry and mechanics parameter in the process of ceramic balls lapping.