Issue of Rigidity of the Ball Screw Nut Exposed to Bending Stress during Bending Stress of the Ball Screw

摘要

Ball screws and nuts represent the inseparable part of machine-tool building. The thread lead accuracy ranges in hundredths of millimetres per 1 m. In addition to the undesirable phenomena caused by heat (dilatability) and, e.g., torsional and transverse oscillations, the bending stress of the ball screw is considerably undesirable too. This stress and at the same time behaviour are transferred to the bending stress of the ball screw nut. This has a very harmful influence on setting of the ball screws, when the machine tool is assembled. Using the analysis by means of the FEM method, the paper conducts a survey of deformation issue of the arrangement "machine – ball screw – ball screw nut" during the assembly stage as well as a survey of compensation possibilities and other technical measures determined to limit the undesirable deformations and stress of the ball screw originating already in the manufacturing stage of the machine tool.