Abstract
The paper presents a thoroughly modified method of solving the problem of vibration suppression when boring large-diameter holes in large-size workpieces. A new approach of adjusting the rotational speed of a boring tool is proposed which concerns the selection of the spindle speed in accordance with the results of the simulation of the cutting process. This streamlined method focuses on phenomenological aspects and involves the identification of a Finite Element Model (FEM) of a rotating boring tool only and validating it with a real object, while dispensing with discrete modelling of a completely rigid workpiece. In addition, vibrations in the boring process in all directions were observed, which implies a geometric nonlinearity of the process model. During the simulation, the values of the Root Mean Square (RMS) of the time plots and the dominant values of the “peaks” in the displacement amplitude spectra were obtained. The effectiveness of the method was demonstrated using a selected mechatronic design technique called Experiment-Aided Virtual Prototyping (E-AVP). It was successfully verified by measuring the roughness of the indicated zone of the workpiece surface. The economic profitability of implementing the method in the production practice of enterprises dealing with mechanical processing is also demonstrated.
Highlights
The relative vibrations between the tool and the workpiece are recognized as the main cause of various problems detected during large-size structures machining [1]
Under certain circumstances occurring in the boring process, they can lead to a loss of system stability and the appearance of self-excited chatter vibrations, due to process and structure dynamic interactions resulting in modulated chip thickness [2]
Discrete modeling of an inherently rigid workpiece was abandoned; the focus was put on the discrete modeling of a boring tool with the use of a set of flexible bars, and on the assessment of model compliance with a real object; vibrations in the boring process were observed in all directions, and the cutting process itself shows the features of geometric nonlinearity due to the dynamic change in the thickness and width of the layer
Summary
The relative vibrations between the tool and the workpiece are recognized as the main cause of various problems detected during large-size structures machining [1]. Under certain circumstances occurring in the boring process, they can lead to a loss of system stability and the appearance of self-excited chatter vibrations, due to process and structure dynamic interactions resulting in modulated chip thickness [2] These can cause a reduction in the overall machine tool performance or the quality of the workpiece surface, increased tool wear, especially when boring large diameter holes [3]. The subject of the article is a method of searching for conditions for minimizing the vibration level of a rotating tool during the boring process in large-size products, based on the results of previous computer simulations of the identified boring tool model. Discrete modeling of an inherently rigid workpiece was abandoned; the focus was put on the discrete modeling of a boring tool with the use of a set of flexible bars, and on the assessment of model compliance with a real object; vibrations in the boring process were observed in all directions, and the cutting process itself shows the features of geometric nonlinearity due to the dynamic change in the thickness and width of the layer
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