The Dynamic Characteristic Analysis Of Inverted Multi Station Turning-grinding Composite Machine Center

Nowadays machine tools industry, dynamic characteristics of a machine tool havebecome complex and research in dynamic characteristic has also been a popular areawith high level requirements in speed, accuracy and automation. Dynamiccharacteristics directly affect the service life, working accuracy and manufacturingefficiency of a machine tool. The investigation about dynamic characteristics of amachine tool is important for seeking defects and optimizing designs in the initialproduct design process.In this paper, virtual prototyping technology and finite element method (FEM)which are based on the multi-body dynamics and finite element theory, are introducedto analyse the dynamic characterises of the CVT cone inverted turning-grindingcomposite machine centre. This thesis provides an important guide in seekingweakness in structure design, shortening design cycle and improving design quality fora machine tool. It also presents a theoretical foundation in this area and can be appliedas a technical reference.Achievements as shown below:1A computational model of the inverted turning-grinding composite machinecentre was created by a3dimensions package Pro/E. And FEM simulations and multi-body dynamic simulations about this computational machine centre model werecreated.2FEM simulations about the machine centre were created by a finite elementanalysis software package, ANSYS. Under maximum cutting forces and gravities ofthe machine tool and work pieces, static stiffness analysis has been performed fordisplacements on the machine tool, the machining tool bed and the saddle. And thefirst eight model natural frequency and principal model for this machine tool havebeen obtained by modal analysis.3A multi-body dynamic model was created by a software package ADAMS basing multi-body dynamics theory and the work processes of this machine centrehave been simulated. Response curves about the feeding displacement, speed andacceleration of the spindle have been analysed. The dynamic accuracy has beeninvestigated and summarised by several influences, such as the saddle weight, thedamping between the guide rail and sliding blocks, ball screws stiffness and bearingsstiffness. It is evident that increasing the stiffness of ball screws and bearings canreduce the displacement, speed and acceleration fluctuation of the spindle feedingmotion and also can improve the motional accuracy of a machine tool. Adding thedamping between the guide rail and sliding blocks or reducing the saddle weight alsohas the above effect.