Analysis And Experimental Research On The Dynamic Characteristics For Motorized Spindle Including Thermal-Mechanical Coupling Effect

Motorized spindle is the core part of high-grade CNC machine tools,which can greatly improve the production efficiency and processing quality of machine tools.However,the thermal-mechanical coupling of motorized spindle is often more complex and violent than that of the traditional spindle system,resulting in easier deformation and failure of parts during work,which not only affects the dynamic performance of the motorized spindle,but also reduces the machining precision of parts.In order to solve the above problems,it is necessary to deeply study the mechanism of thermalmechanical coupling and establish a more reliable coupling model of motorized spindles,so as to accurately predict the dynamic performance of motorized spindle.It is of great significance to guide the structure design of motorized spindle and improve the machining precision of machine tools.Aiming at the deficiency of the existing technology,this paper proposes a thermal-mechanical coupling dynamic model of motorized spindle that considers the direct coupling between temperature rise and thermal deformation,and carry out relevant experiments for verification.The full text work is mainly divided into the following aspects:(1)The static and dynamic characteristics of spindle ball bearing are modeled and analyzed.Based on Hertz elastic contact model,a static and dynamic characteristics model for ball bearings is established.The correlation between each bearing parameter and speed is obtained,and the influence of preload and structure parameters on bearing stiffness is discussed.The results have guiding significance for the structural design and optimization of ball bearing.(2)The dynamic characteristics for spindle-bearing with frictional heat are modeled and analyzed.On the basis of the ball bearing dynamic characteristic model,a spindle-bearing system dynamic characteristic model with frictional heat is established.The operating characteristics and temperature rise of the system at various speeds are analyzed,and the dynamic stiffness of the ball bearing with frictional heat is obtained.Then the relevant changes are reasonably explained.(3)The steady temperature field for motorized spindle based on thermal resistance is analyzed and tested.A thermal network model of motorized spindle based on thermal resistance is proposed according to the theory of heat transfer,and the calculation flow is given.Subsequently,the temperature of motorized spindle and the dynamic parameters of the bearings are obtained.Then the temperature of the motorized spindle is tested to verify the validity of the model.(4)The dynamic characteristics of motorized spindle under thermal-mechanical coupling are modeled and tested.The thermal-mechanical coupling dynamic model of motorized spindle is derived in detail,and the vibration test platform is developed.The motorized spindle unbalance responses are acquired to verify the model.In summary,this paper mainly studies the thermal-mechanical coupling dynamic characteristics of motorized spindle,and designs experiments to verify the model.The experimental results show that the models established in this paper have high accuracy.The relevant conclusions provide a basis for the structural design and optimization of motorized spindle,and have certain theoretical research value and social and economic benefits.