Cutting forces in turning operations
Tutor / director / evaluatorSorby, Knut
Document typeBachelor thesis
Rights accessOpen Access
At first, the idea of this project was to study internal turning operations in order to earn a better knowledge in the possible deflections suffered by the tools performing these operations. A prediction method of the deflections suffered in finishing operations with variable depths of cut is necessary to achieve high accuracy. In order to study the effects of the deflection in different operations and different tools, a study of the forces received by cutting tools in turning operations has been performed. In this study, from the basic knowledge of orthogonal cutting until the specific forces received by the tool and the effects that these can generate in the cutting operation have been studied. The geometry of the inserts used in turning operations have been investigated in order to understand the characteristics that affect in the forces received. Moreover, possible problems that can be suffered in these operations such as vibrations or deflection are studied. The main force studied is the radial force, this cutting force has the highest impact in the studied imperfections. In order to develop a prediction of the cutting forces suffered by the tool, a MATLAB programme has been created with the variable features of tool geometry and cutting conditions. This programme generates a prediction of the chip load area to analyse the forces, it has been tested with different variations to find the most accurate model to predict the cutting forces. Experimental tests with different inserts and increasing depth of cut have been performed in a lathe with a force measurement system to analyse the empirical differences experienced in the cutting forces. These tests confirm that the radial force presents an increasing behaviour until the depth of cut is greater than the nose radius of the tool, after this moment the force gets stabilized. Based on the experimental tests carried on, the prediction method elaborated can be compared and used to establish a good relation between the parameters influencing in the radial cutting force and the empirical results. The comparison appears to be suitable and can be used in the prediction of these forces. A final relation has been studied with the results of the experimental tests. The radial force has been used to predict a deflection in a Silent Tools boring bar. This deflection cause a different depth of cut than the programmed. However, this real depth of cut turns out to present a linear relationship with the programmed.