Modification of Modal Characteristics of Machining Tool Body by Reinforcement with Non-Uniform Cross-Section

Abstract

The various excitation effects are affecting the machining tools during the machining process. Cutting speeds, cutting forces, chip-making manner, the stiffness of MTW (machine-tool-workpiece) system are predominant effects affecting the dynamics of MTW system and also influencing the machining process (roughness of the machined surface, tool wear, tool or workpiece damage, noise generated by the machining process, etc.). In many cases, to achieve of adequate dynamic properties of the tool, the change of modal properties (mode shapes, natural frequencies) of the body tool must be performed using structural modification. The main objective of this paper will be to formulate, analyse and evaluate the proposed methods and procedures for structural modifications of the tool, represented as a beam. A modification of modal properties by insertion of non-uniform cross-section reinforcing core into body tool is studied and the effect of material properties and geometrical parameters of core on modal properties is analysed. The applications of structural modifications of tool body are leading to better conditions in the cutting process.

Modification of rotor modal properties based on structural changes in the stiffness of its bearings and shaft

“…If operating conditions causing a resonance state of the rotor system occur, it is necessary to design the rotor system structure to enable a change in the distribution of its mass, stiffness and damping properties. In the event of a structural change in the rotor system resulting in the redistribution of mass, damping, and stiffness, a modification in the equation of motion (8) is required [4]. After the structural modification, the equation of motion of the rotor system has the following form…”

“…Under these operating conditions, the rotor exhibits inappropriate dynamic parameters, and therefore it is necessary to eliminate undesirable dynamic effects and their transmission to the production equipment, or to the work environment. One of the possibilities to eliminating these undesirable conditions is the design of such a rotor structure IOP Publishing doi:10.1088/1742-6596/2712/1/012022 2 [4,5] which will be able to redistribute the mass and stiffness properties of the rotor during the design stage or even during operation.…”