Drilling Thrust and Torque Prediction of Viscoplastic Materials

A model for drilling of viscoplastic materials is presented. An analytical model is developed for predicting thrust force and torque in the drilling with a twist drill. The thermomechanical properties are accounted for describing the material flow in the primary shear zone and at the element-chip interface. A temperature friction law is introduced. The approach is based on the representing the cutting forces along the cutting lips as a series of oblique elements. Similarly, cutting in the chisel region is treated as orthogonal cutting with different speeds depending on the radial location. The section forces obtained by the model are combined to determine the overall thrust force and drilling torque. The results of the proposed model are compared with experimental results and a good agreement is obtained.