| High-speed machining is a promising advanced manufacturing technology for increasing productivity and reducing production costs dramatically. High-speed machine tool is necessary for realizing high-speed machining, and high-speed motorized spindle is the pivotal assembly of high-speed machine tool. Compared with conventional spindle, motorized spindle is equipped with a built-in motor, so that transmission devices such as gears and belts are eliminated and "zero transmission" is realized. However, it also has a vice.The heat generated due to power loss in the motor and friction in the bearings is significant during high speed machining, and makes bearing's temperature-rise high. The thermal deformation of the spindle owe to the heat decreases the accuracy of high-speed machine tool greatly. This fatal vice badly restricts high speed spindle's development and application. So it is one of the current main contents to research the thermal properties of high speed motorized spindle. This paper firstly introduces the characteristics and heat dissipation of motorized spindle, then illuminates the basic FEA theory of thermal contact, and provides the formula of calculating the thermal load and coefficient of heat dissipation. Secondly this paper utilizes ANSYS to analyze the thermal of properties motorized spindle which was designed by a corporation, and resort to experiment to validate the dependability of the FEA model. In order to improve the thermal properties of motorized spindle, this paper introduces two reformative measures: one is to lubricate the spindle bearings with oil-air; the other is to cool the bearing house by oil. The thermal properties of the mofified motorized spindle by the two reformative measures are analyzed respectively. The analysis result indicates the two reformative measures are effective. Finally this paper analyzes the thermal deformation and stress of motorized spindle, and its influnence on motorized spindle's precision and security. |
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