Correlation between Idling Vibration of Machine Tool and Machining Chatter

Mechanism of the machining chatter caused by the forced vibration on the machine tool is presented with the metal cutting test results. From the presently conceived theory of self-excited chatter, a theory of forced chatter has been derived. According to the theory, the amplification factor of the chatter amplitude to the amplitude of the idle time forced vibration is predicted from the dynamic characteristic of the machine structure, the cutting condition, and the frequency of the forced vibration. The result of turning tests performed with the forced vibration added by a magnetic exciter proves that the amplification factor varies according to the forcing frequency in the way as predicted by the theory. From the theory and the experiment of this study, it is understood that there exist some particular sets of conditions where very high amplification factors are attained although the ratio is not greater than unity except at these conditions. The forcing frequency above the resonance frequency but in the resonance range is particularly unfavorable due to the generation of the forced chatter

Parameters of Mounting and Foundation Affecting the Structural Dynamics of Machine Tools

The effect of mount and foundation on the structural dynamics of machine tool was studied by theoretical analysis along with experimental methods. The frequencies and mode shapes of the resonance modes to which the mount and foundation have decisive effect are analyzed by a theoretical model, a scale model test, and tests on several actual machines. Based on the harmonic response test of a concrete foundation, the empirical values of the principal parameters of the mount and foundation influential to the machine dynamics are identified. They include the stiffness of the concrete foundation surface on which the machine is mounted, and the ground modulus of the soil supporting the foundation

Cutting Dynamics Associated with Vibration Normal to Cut Surface

Investigation into the dynamics of the metal cutting process has been carried out using a new experimental method to identify the cutting stiffness without directly measuring the dynamic cutting force. Comparing obtained data to the theoretical formula, it has been determined that the theoretical model proposed by Das and Tobias in 1967 is valid with respect to the inner modulation effect. Effects of cutting conditions, wave length of chatter mark, and built-up edge formation on the onset of the regenerative-type self-excited chatter are also investigated

Active Suppression of Chatter by Programed Variation of Spindle Speed

By a programed variation of the spindle speed of machine tools, it is possible to control the onset of regenerative-type self-excited chatter, which restricts the maximum depth of cut allowable in rough cutting operations. This paper presents a theoretical basis of this phenomenon, together with experimental proofs demonstrated in turning operations

Fundamentals for Vibration Diagnosis by Ground Surface Marks

Ground surface imperfections are often attributed to periodical marks caused by vibration in grinding. According to the mechanism by which the marks were formed, there are various characteristics which can be important clues to diagnosing the type of grinding vibration and making appropriate counterplans. By classifying the marks due to each type of grinding vibration experimentally as well as theoretically, they can be divided into two categories depending on whether the marks were formed chiefly by a shape error or by a roughness variation. In addition, the relationship between the presence of the marks and the speed ratio, and the marks\u27inclination to the wheel axis are generalized to correspond with the different grinding processes and types of grinding vibration. The generalized relationships make it possible to narrow down the possible causes to a few types of vibration. Also, an optical method which is necessary for the diagnosis is proposed for measuring the characteristics of the marks. Together with the principal counterplans for each type of grinding vibration, a system of knowledge for vibration diagnosis has been obtained.・rights：日本機械学会・rights：本文データは学協会の許諾に基づきCiNiiから複製したものである・relation：isVersionOf：http://ci.nii.ac.jp/naid/110002502351