In recently, it is demanded development of manufacturing techniques for machining of various mechanical parts. Therefore the development of turning is one of the important manufacturing techniques. In this study, an experimental shape in tapered groove turning was suggested, and the turning process was investigated by analyzing cutting speed, feed rate, tapered angle, depth of cut. The surface roughness and cutting force change in the workpiece was measured. From the results, the optimum machining conditions are obtained by design of experiments.
To increase the machine accuracy by improving the stiffness of spindle bearings, preload was applied to the spindle bearings. The methods of fixed position preload, convertible preload, constant pressure preload, and variable preload are used to apply the preload to the spindle bearing. The previous studies performed by the author of this study were variable preload methods using rubber pressure and centrifugal force based on mechanical systems. This study proposed a toggle joint mechanism that could be applied to variable preload method using centrifugal force and rubber pressure to increase the preload. Also, a finite element analysis was conducted to predict the deformation of the rubber and change of the preload. And the analysis results showed that the preload by the device using rubber pressure only was increased by the toggle joint mechanism using rubber pressure.