Study On The Thermal Characteristics Of A Magnetically Suspended High Speed Machine Tool Spindle

In this paper, the thermal characteristics of a magnetically suspended high-speed milling spindle are examined numerically and experimentally. The investigated spindle system includes built-in AC induction motor with power 5.5 kW and maximum speed 70,000rpm, HSK-32C tool holder and 5-axis active magnetic bearing system. The temperature distribution is analyzed numerically with finite element method considering heat generation due to power losses in magnetic bearings and built-in motor. The heat generation rates and heat transfer coefficients in spindle elements are calculated from some empirical equations. By experimental analysis, the temperature at the spindle system includes stator of magnetic bearings and motor and rotor are measured in various rotational speed conditions and cooling conditions.