High-speed Grinding Electric Spindle Temperature Rise And Dynamic Characteristics Of Study

High speed cutting and high speed machining taking high cutting speed, high feed speed and high machining precision as main characters is one of advanced manufacturing technology nowadays. High speed NC machine tool with high speed and high precision is the key factor to realize the high speed machining. High speed spindle is the core component of a high-performance machine tool. With the fact that the promptness developing and. being perfected of the electric drive technology, systematic machinery of the high speed NC machine tool' main drive structure has already got extremely simplification, has canceled wheel drive and the gear drive mainly. The motorized spindle of machine tool is direct drove by a built-in motor, thereby; the main transmission chain length of machine tool has been shortened for zero, and realized "zero transmission" of machine tool. That the drive structure form of the motorized spindle and motor "two combined into one" makes the motorized spindle component be independent relatively from the transmission system and the whole structure of the machine tool, be made as "the motorized spindle unit", the popular name "the motorized spindle" therefore.To a great extent, the construction design, the thermal characteristics 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 thermal characteristics and dynamic performances of the motorized spindle on improving the performance of the high speed machine tool.This paper takes the motorized spindle used in a high speed grinding machine tool as the study object, realizing high speed, high accuracy as a target, studies the thermal characteristics and dynamic performances of the motorized spindle in FEM based on the software ANSYS. Specific details of the paper are as follows:(1) The structure of the high speed motorized spindle is analyzed, the main components like the spindle motor, the spindle bearing, the lubricating system and the oil-water heat exchange cooling system on the stator of the motor are studied, besides, a key parameters, the interference depth between motor rotor and the shaft, needed at the stage of designing are analyzed and calculated.(2) The heat transfer mechanism is analyzed; the heat source and the heat transfer coefficient of every part are calculated according to the actual working condition. On this basis, the thermal-structure coupling analyses of the motorized spindle unit studied in the thesis are done by the FEA software ANSYS, the temperature field, the temperature rises of the bearings and the thermal deformation in the front end of the motorized spindle are calculated, and the reasonable and effective measure is suggested.(3) The structure form, the forcing and dynamic characteristic of the peculiar bearing form of Si₃N₄4 Angular-contact ball bearings adopted in the motorized spindle unit on the high speed condition are analyzed, and the stiffness is also calculated. On this basis, the dynamic characteristics of the motorized spindle is analyzed, and the effect on the natural frequency by the pre-tightening force is also supplied by the experiment, which provides the necessary theory basis for optimizing the structure and improving dynamic behaviors of the motorized spindle, also establishes a basis for the research and application about the high speed spindle.