Selection of form factors of machine carrying systems in reliance on the process duty

Problems of dynamic behavior in load-carrying systems of technological machines under operational conditions are discussed. The goal of this study was to develop recommendations for selection of the fabric assortment for these machines (using an STB loom as an example). This study is urgent due to the lack of recommendations for selection of technological equipment and unified methods for account of the dynamic character of a technological force. The precision of the computational model for carrying systems, suggested by the authors earlier, is improved in this study by introducing additional elements required for operation of looms during production of the determined fabric assortment. The frequency spectrum of intrinsic vibrations of load-carrying systems for a series of STB looms with widths 180, 190, 220, 250 and 330 cm were determined more precisely using SolidWorks CAD system and finite-element CAE complex ANSYS. The first frequency varies in the range from 24.9 Hz (STB-180 loom) to 17.7 Hz (STB-330 loom), second frequency varies from 26.7 Hz to 20.8 Hz, and the third one varies from 54.8 Hz to 25.2 Hz. It is demonstrated that the technological loading from tension of warp fibers can be presented as loading from static force from preliminary tension of the mobile ram spring and dynamic component depending on operation of the machine mechanisms. It is also demonstrated that load-carrying systems of looms under certain operational conditions can approach resonance conditions. Movements of individual elements in load-carrying systems caused by technological loading presented by a Fourier series are determined. The obtained results make it possible to develop specific recommendations for discrimination of assortment ranges of STB looms in accordance with the requirements to hygiene and sanitary conditions during work on this equipment. During design of technological equipment, it is suggested to use technological loading in the form of a sinusoidal pulse with the period equal to turnaround time of the loom main shaft and amplitude equal to the static component of the acting force for chosen fabric assortment. Using the frequency spectrum of forced vibrations obtained by expansion of the technological loading in a Fourier series, it is suggested to develop constructions of load-carrying systems from the ratio between frequencies of forced and free vibrations equal to three or higher.

load-carrying system, technological machine, finite-element method, the frequency spectrum of intrinsic vibrations, the technological loading, series of STB looms, forced vibrations, resonance