Workpiece Spindle Research Articles

Analysis of chatter vibration in the end milling process

This paper continues the work of a previous paper by the authors. A different approach is applied, which adopts frequency domain analysis by linearizing the nonlinear equations to investigate the dynamic behavior in the milling process. A new relationship among the limiting axial depth of cut, workpiece fundamental natural frequency and spindle speed is constructed, and the obtained stable region is also consistent with that of the previous paper.

Determination of the Dynamic Characteristics of Machine Tool Structures

The ‘operative harmonic response locus’ of a machine tool structure, which is required for the prediction of machining stability, must be determined by vibration tests carried out under conditions which simulate closely those arising during cutting. This requires that such tests be performed while the tool or the workpiece spindle is rotating, the vibrations being excited by a small harmonic force superimposed on a large constant pre-load. It is not possible to satisfy these conditions with vibrators working on electro-dynamic or electro-hydraulic principles and so an electro-magnetic vibrator was designed and developed to meet the above requirements (2). This excitor can be used with all types of machine tools, but in the present investigation its application is restricted to lathe and horizontal milling machines. The effects of the rotational speed of the lathe spindle and milling machine spindle, of the exciting force amplitude and of the pre-load magnitude and direction on the response data, are investigated. It is found that the lathe structure behaves in a linear fashion whereas the behaviour of the milling machine is non-linear.