The works of Nakayama et al. represent the prevailing view on how the geometry of 3-D helical chip relates to the radii of its up-curl and side-curl. The view is re-examined in this paper and it is ...shown that the corresponding definitions of the radii are ambiguous. Six sets of alternative hypothetical definitions of up-curl and side-curl radii, which are consistent and plausible when examined from the viewpoints of 2-D up-curl and side-curl, are identified and the respective expressions are derived from a geometric analysis of 3-D chip. The hypotheses are tested using six criteria. It is found that the expressions for the radii of up-curl and side-curl proposed by Nakayama et al. do not satisfy one of the criteria whereas a new solution satisfies all the criteria. Part 2 extends the 3-D geometric analysis and discovers a number of new implications.
The geometric analysis of 3-D chip forms developed in Part 1 is extended and several new implications are identified: (i) the geometric properties at every point on the tool–chip separation line are ...fully determined once those at any one point are known, (ii) all possible 3-D chip forms are confined to a relatively restricted parameter space defining the chip velocity direction and the orientation of the axis of the helical chip, (iii) 3-D helical chips are only approximately conical, and (iv) the radii of up-curl and side-curl can be determined from a set of simple measurements of the chip-in-hand. Unlike past analyses, the new analysis paves the way to the study of chip forms from empirical data obtained from practical 3-D chips.
In order to assure system reliability in FMS and unmannned machining, automatic sensing devices are required. The in-process recognition of chip forms is one of the most important technologies for ...the completely automatic operation of machine tools. In this study, the dynamic component of cutting force closely related to chip breaking has been measured to recognize chip forms. From the measured results on various cutting conditions and tool geometries, especially those having crater wear, the relationship between the chip form and the dynamic component of cutting force has been investigated. As a result, it can be verified that the dynamic component of cutting force adequately processed using the cut-off frequency (80-500 Hz) reflect exactly the conditions of chip breaking, and has a periodic component. Accordingly, it is possile to recognize the states of chip formation, and to tell which chips can be easily handled, by monitoring the maximum amplitude of the dynamic component of cutting force.
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