Operational effects on the stiffness of combined roller and plain bearings

Abstract

The use of electric servo drives in presses enlarges the possibilities of controlling forming processes and enables an optimization of processes with regard to technological, economical and qualitative aspects. However, high process dynamics, oscillations or rest positions without movement lead to increased demands on the machine elements, especially the bearings. As press forces increase, the use of conventional roller bearings becomes less and less economically viable. Thus, plain bearings are widely used, which are characterized by a non-linear force-displacement transfer function especially at low rotational speed. To meet the requirements, combined roller and plain bearings were developed and investigated. Control of forming processes demands for a continuous force-displacement behavior as well as high machine stiffness. Therefore, the effects of typical forming operations on the stiffness of combined roller and plain bearings are investigated and presented in this article.