Computational modeling of ultrasonically assisted turning

Abstract

Ultrasonically assisted turning (UAT) is an advanced machining technique, where high frequency vibration (frequency f ≈ 20 kHz, amplitude a ≈ 15 µm) is superimposed on the movement of the cutting tool. Compared to conventional turning (CT), this technique allows significant improvements in processing intractable materials, such as high-strength aerospace alloys, composites and ceramics. Superimposed ultrasonic vibration yields a noticeable decrease in cutting forces, as well as a superior surface finish [1].

The paper presents a three-dimensional thermomechanically-coupled finite element (FE) model of both UAT and CT that was recently developed as an extension of the initial 2D model [2]. The current model enables studies of various 3D effects in turning, such as oblique chip formation, as well as the influence of the tool geometry on process parameters, e.g. cutting forces and stresses generated in the workpiece material. The model allows transient, coupled thermomechanical simulations for elasto-plastic materials with strain-rate sensitivity. Chip shapes and forces acting on the cutting tool are analyzed. Stress, strain and temperature distributions in the cutting zone are studied. The effects of cutting parameters (such as the feed rate) and influence of friction on both UAT and CT are investigated. Numerical results are validated by the experimental tests performed at our in-house UAT prototype.