Thermal Characteristics Analysis And Modeling Technology Research Of High-speed Motorized Spindle

High-speed motorized spindle is a key component of CNC machine tools for high-speed and highprecision machining.Its working performance has a great impact on the machining accuracy and production efficiency of CNC machine tools.Thermal characteristics are important factors reflecting the working performance of motorized spindles.If the temperature of motorized spindles is too high,and the deformation is too large,the machining accuracy may be reduced.This article takes the Setco231A240 high-speed motorized spindle as the research object,and employs the theoretical,simulation and experimental methods to analyze the thermal characteristics of the motorized spindle.The specific research contents include:(1)Based on the heat transfer theory,the main heat sources of the motorized spindle are analyzed,and the heat generation model of the built-in motor and bearings are established.The heat transfer mechanism of the motorized spindle is analyzed,and the convective heat transfer forms of the oil-air lubrication and cooling system are studied in detail.Based on the basic heat transfer equations,the calculation methods of the heat generation and heat transfer coefficients of the motorized spindle are given,which provides support for the subsequent thermal characteristics analysis.(2)Based on the thermal resistance network method,through the basic calculation formula of thermal resistance,considering the different convection forms of the spindle,a thermal resistance calculation model of the high-speed motorized spindle is established.A thermal network model is buillt according to the structural characteristics of the motorized spindle.The thermal balance equations are given based on the Kirchhoff energy balance principle.The temperatures of key nodes are calculated by Matlab using the Newton iteration method.(3)The fluid domain and solid domain models of the motorized-spindle are created by Creo.The differences between the two solutions of the coupling problem,namely one-way coupling and two-way coupling,are analyzed.Based on the fluid flow control equation,the basic thermal analysis equation and the structural analysis equation,the finite element model of the motorized spindle is built,and the temperature field and thermal deformation are obtained.Temperature and deformation measurement tests are performed on the test platform to measure the temperature rise and deformation at different speeds.The test data are compared with the simulation data and the theoretical data to verify the accuracy of the thermal-fluid-structure finite element model and the thermal network model.The temperature field is also verified by comparing the theoretical data and the simulation data at specific working condition.(4)Based on the established thermal-fluid-structure finite element model,the effects of speed,coolant flow rate,coolant temperature,air flow rate,and preload on the thermal characteristics of the motorized spindle are analyzed using single-factor analysis and response surface method.Curves of temperature and deformation changes,and response surfaces of different factors and deformation are given.Different combinations of working condition parameters are obtained to meet the requirements that the motorized spindle temperatures or deformations are at specific range.