Experimental Investigation Of Sound Signals During Machining Process

With the improvement of living standard and the increasing awareness of environment protection, people are paying more and more attention to noise controls. However, few researches on the noise during cutting process, especially on the noise during milling, were found in literature review. In order to decrease the noise pressure, the most important manufacturing methods including both turning and milling operations are studied in this thesis. The research contents are as follows:(1) The concept and terminology of noise are introduced.(2) On the basis of the analysis of the effect factors on the noise during machining process, the workpieces are machined on lathes. Firstly, the effects of spindle speed, depth of cut, and feed rate on the noise during machining process are studied. The effect results produced from each above factor are obtained though the turning experiments. Then, the seven-factor-two-level Taughi experiments are carried out to investigate the relationships between cutting parameters and the noise. Finally, the theoretical explanation is given.(3) Effects of cutting parameters on noise during turning are also studied on CNC turning center, which shows the relationship between cutting parameters and the noise. The results from plain lathe and those from CNC turning center are compared. Research of the relationships between coefficient of friction and sound pressure level of friction with several different inserts, which is to explain the effects of cutting parameters on the noise during cutting process. The relationships between cutting parameters and the noise pressure level are explained by tribology, the measure for reducing noise during turning is given.(4) The effects of cutting speed and radial depth of cut on pure cutting noise are studied with milling experiments on a CNC vertical machining center. It comes to the conclusion that the main pure cutting noise frequency band is at 1000Hz or so. By the analysis of the milling force dynamic signals and the sound signals during machining process, it shows that the composing of the milling force dynamic signals is similar with that of the sound signals during machining process. It also shows that the effect on the pure cutting sound pressure signal caused by the cutting speeds and radial depth of cut are related to the dynamic milling force signals. This thesis is supported by Excellent Postdoctoral Foundation of Shandong Province (200602008) and the Program for New Century Excellent Talents in University (NCET-04-0629).