Prediction of diameter errors in bar turning: a computationally effective model

Machining accuracy can be considerably affected by the deflections of the m achine-workpiece-tool system as well as the thermal expansion of material d uring machining. An improved model for predicting dimensional errors in tur ning process is presented. This model uses a geometric analysis in the mach ine frame, in which the elastic deflections of the machine-workpiece-tool s ystem due to the cutting force are studied. In this paper, our workpiece de flection model [A.-V. Phan, G. Cloutier, J.R.R. Mayer, International Journa l of Production Research 37 (1999) 4039-4051; G. Cloutier, J.R.R. Mayer, A. -V. Phan, Computer Modeling and Simulation in Engineering 4 (1999) 133-137] earlier developed is employed. As described in Phan et al. (1999), this de flection model is general, accurate and computationally effective thanks to its closed-form solutions derived from the finite element technique. Also, due to the coupling between the cutting force and actual depth of cut, ite rative computations are performed to obtain the coupling value of this forc e which provides further accuracy to the prediction. Finally, via numerical examples, the predicted diameter error on a workpiece, the ratio between t he coupled cutting force and its nominal value along the part axis as well as the influence of the cutting force components on the error prediction ar e computed using the proposed model. The results provide additional insight into the error formation in the turning process. (C) 2000 Elsevier Science Inc. All rights reserved.