Modelling And Analysis Of Static And Dynamic Performance Of Numerical Control Rotary Table In Compound Grinding Center

Compound processing technology is being widely developed and applied in grinding and metal machining globally because of its powerful and comprehensive processing capability.Precise flexible compound grinding center as high precision processing technology and equipment are urgently needed in precision machinery industry in our country.The B-axis grinding wheel NC rotary table of the compound grinding center is equipped with modular grinding heads.The integration and conversion of various grinding processes in compound grinding centers are accomplished through the high accuracy in rotating and locking of B-axis NC rotary table.The B-axis NC rotary table is a core component of the precision compound grinding center.Therefore,it is necessary and meaningful to study the static-dynamic performance of the B-axis NC rotary table.This thesis focus on the multiple grinding function demands of compound grinding center.Research on the rotary table structural configuration schemes optimization method,driving pattern of smooth position switching and reliable locking principle were conducted.The dynamic model of force-jointed mechanical joints was established based on the detachable bolted joints connection between rotary table and modular grinding heads and the brake structure using hydraulic pressure between rotary table and grinding carriage.Therefore FEM simulation study on the static-dynamic properties was conducted.Specific content are as follows:Firstly,analysis and optimizing of the rotary table were conducted.Grinding heads layout schemes were compared and optimized using fmincon function in Matlab.Deformation of the rotary table under different working condition were compared using FEM analysis.Common acceleration-deceleration curves were compared and the parameters of acceleration-deceleration curves were optimized.Performance demands of high rotating and locking accuracy of the rotary table were satisfied.Secondly,theoretical modelling,FEM simulation and experimental validation were conducted on the dynamic properties of frequently-used mechanical joints.Based on the non-uniform pressure distribution and the fractal contact theory,the pattern of non-uniform pressure distribution was obtained through static simulation analysis and a dynamic model of the dynamic parameters of jointed interface was established.By converting the dynamic parameters of jointed interface to the properties of virtual material,the theoretical natural frequency and modal shape were acquired through FEM analysis.Comparing the theoretical modal to experimental modal,the proposed model can accurately describe the natural frequency and modal shape of mechanical joint.Finally,simulation analysis and optimization were conducted on the static-dynamic properties of rotary table.The preceding modeling method of mechanical joints was applied to the FEM modeling and analysis of the rotary table.A FEM model of the overall unit of rotary table was established.Simulation analyses of natural frequency,modal shape and static deformation were carried out under different working conditions.The optimization plan of the static-dynamic properties of the rotary table was put forward.