High-speed Electric Spindle Dynamic Finite Element Analysis Of Static Characteristics

High-speed machining is a promising advanced manufacturing technology for increasing productivity and reducing production costs dramatically. High-speed machine tool is the precondition for realizing high-speed machining. High-speed motorized spindle is a critical unit of the high-speed NC machine tool and the machining center. Compared with conventional spindle, high-speed motorized spindle is equipped with a built-in motor, so that power transmission devices such as gears and belts are eliminated and "zero transmission" is realized.To a great extent, the construction design, the static and dynamic performances of the motorized spindle determine machining qualities and cutting capabilities, and are the important factors influencing the precision of the high-speed NC machine tool. It is important to study the construction design and optimization of the static and dynamic characteristics of spindle on improving the performance of the high-speed machine tool.In this paper, the design and construction, the static and dynamic characteristics of the motorized spindle are studied thoroughly using ANSYS software by FEM. Details of studies are as follows,1. The construction of the high-speed motorized spindle and the influences on the static and dynamic performances of spindle are studied, and the construction of the motorized spindle is designed based on satisfying the static and dynamic performances.2. By the modeling and analysis of force characteristics for Angular Contact Ball Bearing, the static stiffness of bearing for the motorized spindle is calculated using simple method, and the influence of preload on static stiffness of bearing is studied, and a set of accurate simplified formulas on the dynamic stiffness of bearing are summarized by the analysis of dynamic characteristics for high-speed Angular Contact Ball Bearing.3. A two-dimensional FEM model of the motorized spindle is built up withANSYS, the static stiffness of spindle is studied and the influence of preload on it is also analyzed in detail.4. A more accurate three-dimensional FEM model of the motorized spindle is established. Based on the model, the modal and response characteristics of the motorized spindle are analyzed. The natural frequency, vibration mode and limited speed are studied. The influence of preload on first set of natural frequency of spindle is analyzed. The maximum dynamic displacements of the front end, rotor and sensor on spindle are studied, therefore, the rationality of the spindle design and construction will be validated.5. At the end of paper, the motorized spindle has been taken as an experimental object, a set of dynamic measuring system has been built up, and the experiment of dynamic response characteristic is conducted with impulse excitation. The comparison between theoretical simulation and experimental result shows that the rationality and validity of the simulation model are validated. Furthermore, some effective methods have been put forward to improve the dynamic performance of the high-speed motorized spindle.