Research On Static And Dynamic Characteristics Of Camshaft Grinding Machine Spindle System Under The Condition Of Electromagnetic Bearings Auxiliary Support

The internal combustion engines required for automotive engines and various transportation vehicles require reliable quality,long service life,low environmental pollution,and low energy consumption,all of which require the high-precision and high-quality camshafts of their core components.With the continuous improvement of the quality requirements of the camshaft surface,the improvement of the performance of the camshaft grinding machine has become an urgent problem to be solved.The camshaft grinding machine is the most important machining machine to ensure that the camshaft was finally formed into a product.Moreover,China’s manufacturing industry has experienced many years of rapid development.In-service machine tool equipment has long been responsible for heavy processing tasks,and the accuracy and performance degradation of in-service machine tools was serious.Therefore,it was a research hotspot for how to remanufacture the machine tool,improve the comprehensive performance of the grinding machine,how to suppress the bending deformation of the electric spindle,improve the grinding stability,increase the critical speed of the electric spindle,and maximize the economic benefits.Based on the MKS8318 camshaft grinding wheel spindle system,this paper aims to suppress the deflection of the spindle,improve the static and dynamic characteristics of the spindle system of the grinding wheel,and improve the machining performance of the machine by applying electromagnetic bearings between the motor rotor and the mechanical bearing of the electric spindle.Using the combination of theoretical derivation,finite element simulation and experimental testing,the deflection deformation analysis and performance analysis of the spindle system were carried out.The paper mainly completed the following work:(1)The new structure of the camshaft grinding machine spindle system with electromagnetic bearing was constructed.Under the special consideration of centrifugal inertial force,the mechanical model of the camshaft grinding machine electric spindle was established,and the equations of compensation electromagnetic force and spindle deflection curve were derived.At a certain speed,Under the condition of grinding force,the maximum deflection of the spindle axis of the new structure and the vertical displacement at the grinding head were calculated,and the bending deformation data of the whole shaft span with the best electromagnetic force compensation at different speeds is obtained.(2)The three-dimensional modeling of the new structure grinding wheel spindle with electromagnetic bearing was established by using Soildworks software.The ANSYS Workbench finite element software was docked,and the static structural module was used to analyze the bending deformation of the spindle with additional spindle speed.Comparing the bending deformation difference between the existing grinding machine and the new structure grinding machine,the inhibition rate of the bending deformation of the camshaft grinding machine using electromagnetic bearing technology was calculated.(3)The ANSYS Workbench modal analysis module was used to study the important low-order natural frequencies of the new structure grinding machine spindle and the grinding wheel spindle system and their corresponding vibration modes,and the critical speed of the system corresponding to each frequency was calculated.The spindle system was obtained by the ANSYS Workbench harmonic response analysis module.The displacement frequency response curve was used to solve the resonance interval of the new structure spindle system.Comparing the natural frequencies of the existing grinding machines,the rationality and success of the new structural design were confirmed.(4)A new structural spindle system modal test and test system was established.Under the existing experimental conditions,a mechanical hydraulic device that can replace the electromagnetic bearing is designed.The modal test of the new structure spindle system was carried out by the hammer excitation method.The obtained results were compared with the finite element simulation results.Within the error range,it is confirmed that the improved natural frequency and critical speed of the electric spindle equipped with the electromagnetic bearing were improved.