Thermal Performance Analysis And Optimizationof The High-speed Ceramic Motorized Spindle

The core component of high-speed machining is high- speed motorized spindle, which has some obvious advantages compared with conventional spindle. However, during the process of operating, non-uniform heating of the spindle causes the significant thermal deformation in the front of the spindle, which affects machining accuracy. So, finite element simulation software is used to determine the extent of thermal deformation,which decided by the thermal performance of spindle,in the front of spindle, and obtain the temperature field and displacement field of spindle,which purpose is to solve the problem about the machining accuracy of machine tool that caused by the state of thermal performance and provide a reference for the motorized spindle structure optimized design in the future. In this paper, the main research works are as follows:(1)The heat sources heating and convective heat transfer of the ceramic motorized spindle are analyzed. Based on the ceramic motorized spindle structure and heat transfer theory, the heat generation of heat sources in spindle, convective heat transfer coefficients of spindle and external and contact thermal conductivity in the bearing were analyzed and calculated at the steady state of the spindle.And the relevant theoretical formulas that originate from the convective heat transfer coefficients were analyzed.(2)The temperature fields of the ceramic motorized spindle are analyzed. According to the typical working conditions of motorized spindle, the loads of the finite element analysis model were calculated and the software of ANSYS was used,and the steady and transient temperature fields of the spindle are obtained, which shows that the highest temperature region of spindle is clearance between the stator and rotor of motor in the heating process, and distribution rules of its temperature- rise on bearing inner ring, roller,and bearing outer ring is step by step rise, and spindle temperature effects the bearing temperature-rise.(3) The displacement fields of the ceramic motorized spindle are analyzed. In order to get more accurate displacement solutions of the spindle, the sub-model of the main shaft was established by interpolating boundary and the sub-model of the temperature field was obtained,then based on it, the thermal-structural coupling of sub-model was analyzed and distribution rules of its displacement were obtained. Through the analysis, some rules are found that the total displacement in the front of the ceramic motorized spindle is smaller than the steel motorized spindle, and the displacements in the front of spindle did not show a sudden change in the heating process.(4) Ceramic motorized spindle optimization. Optimization of the spindle structure is conducted with the distance between the machining end and bearings as design variable and the thermal induced deformation of machining end as objective variable.