Shu Karube

Analysis of chatter suppression in vibration cutting

Abstract The occurrence of chatter is strongly influenced by the tool geometry in conventional cutting. Therefore, the tool geometry is regarded as a very important factor. On the other hand, it is known that vibration cutting is capable of cutting hardened steels. However, the theoretical explanation for finish hard-cutting with vibration cutting is still unknown. In this paper, experimental investigations show that chatter is effectively suppressed without relying on the tool geometry, and the work displacement amplitudes are reduced from a wide range of 10–102 μm to the range of 3–5 μm by applying vibration cutting. In order to study the precision machining mechanism of vibration cutting, a new cutting model which contains a vibration cutting process is proposed. Simulations of the chatter model exhibit the main feature of chatter suppression in vibration cutting. The simulation results are in good agreement with the measurement values and accurately predict the work displacement amplitudes of vibration cutting.

The effect of tool nose radius in ultrasonic vibration cutting of hard metal

A tool edge with a small nose radius can alleviate the regenerative chatter. In general, it is important for conventional cutting to use the smallest possible tool nose radius. However, a sharp tool shape has an adverse effect on tool strength and the instability of machining process still occurs. Previous researches have shown that vibration cutting has a higher cutting stability as compared with conventional cutting. In the present paper, the influence of tool nose radius on cutting characteristics including chatter vibration, cutting force and surface roughness is investigated by theory. It is found from the theoretical investigation that a steady vibration created by motion between the tool and the workpiece is still obtained even using a large nose radius in vibration cutting. This article presents a vibration cutting method using a large nose radius in order to solve chatter vibration and tool strength problem in hard-cutting. With a suitable nose radius size, experimental results show that a stable and a precise surface finish is achieved.

The non-linear phenomena in vibration cutting system: The establishment of dynamic model

Abstract It is well-known that vibration cutting is an effective method to cut materials with accuracy. However, it often suffers from unevenness of surface roughness caused by the non-linear vibration phenomena in tool–work vibration system. To solve this problem, we propose a vibration cutting model described by two-dimensional differential equations to analyze the non-linear phenomena. This non-linear model reproduces the basic features of the real vibration cutting systems, that is, the reduction of the cutting force and the displacement of work by pulsing of the cutting force. In this report, our experiment shows that various non-linear phenomena exist in the vibration cutting system. Our non-linear model for the vibration cutting produce behaviors which qualitatively agree with these various non-linear phenomena. These behaviors can be classified by the Lyapunov exponents.