STUDY ON DEEP-HOLE BORING BY BTA-SYSTEM SOLID BORING TOOL - BEHAVIOR OF TOOL AND ITS EFFECTS ON PROFILE OF MACHINED HOLE

The effects of tool vibration on the hole profile in deep drilling are examined by analyzing the vibration with respect to frequency. Further, the mechanism and the causes of formation of multicorner shape in holes with a high length-to-diameter ratio are discussed. It is concluded that the frequency of the bending vibration of the boring bar during machining of the holes corresponds to the number of the corners of holes. From the fact that pentagonal shaped holes are produced frequently, the BTA system solid boring tool is supposed to behave like the equally spaced four-cutting-edge tool. This behavior is clarified through measuring the movements of the boring bar axis. The forming of multicorner-shaped hole itself may be due to a kind of self-excited vibration which is induced by the vibratory movements of the tool axis.