Design of An Active Workpiece Holder

Abstract

Milling is one of the most used machining processes thanks to its high flexibility and high achievable quality. The performance of milling machines is constantly increasing, improving the convenience and increasing the competitiveness of this operation. However, the trend of performance improvement has found a technological limit: self-excited vibrations due to the dynamics of the system machine-workpiece-tooling (i.e. chatter). Chatter is the most dangerous dynamic phenomena that could happen during milling; due to its regenerative nature, it could lead the machine and the tooling system to a heavy fault or to the disruption of the workpiece. This paper develops an active workpiece holder that avoids chatter vibrations by a smart actuation of the workpiece. The design of the workpiece holder is a difficult task due to strict product requirements and the need to create a decoupled structure. The decoupling of the structure is a fundamental requirement of the product because this affects the controllability of the system. Axiomatic Design Theory is used to support the definition of the product requirements and the product architecture. After the definition of the optimal structure of the workpiece, the design features are integrated in order to obtain a functional decoupled structure.