Abstract
When polymers are compared with metals, they have a distinctive characteristic, or viscosity. This paper describes the numerical analysis of cutting process of polyvinyl chloride (PVC) as a viscoelastic, plastic material. In this analysis, the mechanical behavior of the polymer is expressed by a simple model, which consists of three parameter solid and plastic element connected in series. Besides its material properties such as coefficients of viscoelasticity and flow stress characteristic reported in the previous papers, the variations of elastic moduli with temperature and stress were obtained empirically, and the friction characteristic on the rake face was found to be similar to those in machining of metals. Using these properties, the steady state cutting process was simulated by the repeated revisions of strain, strain rate, temperature and yield stress of finite elements and flow lines. The results obtained are high shear angle, thin plastic zone and peculiar temperature distribution where temperature at the free chip surface is much higher than at the rake face, which are apparently different from those in metal cutting simulations. Chip springback after quick stop of machining were further simulated. The large scale springback, which is obseved in experiment, was also realized in this simulation and it is concluded that the temperature dependence of elastic moduli exerts a strong influence upon the behaviour of PVC.
