The study of the curvature of the axis of the processed shaft when based in the centers using a steady rest

Abstract

This paper presents the analysis and results of the study of a two-stage shaft fixed in dead centers and a rest device. Cutting forces act on the shaft, causing a bending moment. The analysis of the curvature of the axis of the workpiece, processed on a lathe when based in the centers, using a rest device, is carried out. The formula of elastic displacement of the workpiece axis at the place of the resulting cutting force is obtained. Diagrams of the stresses of the shaft axis displacements are constructed and a conclusion is made. The analysis showed that the greatest deflection is at the point of the cutting forces acting on the shaft. The quality of the part obtained after processing is characterized by accuracy. The parts mating in the product and, as a result, the overall reliability depends on how accurately the size and shape of the part will be maintained during processing. Parts with length of 10 to 12 times larger than the diameter are bent under the action of their own weight and cutting forces, as a result of which they get a barrel-like shape. It is possible to eliminate this by applying special devices for the machine. When processing long nonrigid workpieces, the tools, jigs and fixtures must evenly distribute the clamping force over the surface of the part. These conditions are well provided by technological equipment with pneumatic, hydraulic clamping devices, as well as with various collet clamps, split bushings, diaphragm or cartridges. When processing long non-rigid shafts, rest devices are used. The rest device plays the role of the main or secondary support when working with workpieces; it creates support for large, long parts during processing. It helps to avoid the risk of damage and deformation of the workpiece or the cutting elements of the machine, by giving the workpiece additional stability