RESEARCHES ON THE NECKING-IN PROCESS USED FOR MANUFACTURING HOLLOW REVERSED CONICAL PARTS

摘要

The necking-in process is a forming operation which shapes a hollow cylindrical part into a conical one, by inner shifting of its wall. Even it is a relatively simple operation, the stress and strain state is not yet well established. The most frequent problem which occurs is the unwanted deformation of the part's bottom. This paper presents the authors' opinion on the stress and strain state. In some diagrams there is presented the influence of the main geometrical parameters on the maximum stress values. There are also presented the results of some experiments made to reveal the influence of the process parameters on the intensity of the part's bottom deformation. Based on these, there are proposed some solutions to avoid the geometrical defects which may occur.