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unilogo University of Stuttgart
Institute of Engineering and Computational Mechanics

Investigation of the Influence of the Dynamics
of Parallel Kinematic Machine Tools
on the Stability of High Speed Machining Processes


Project Description

Production accuracy and quality are influenced by many effects at high speed machining with parallel kinematic (PK) machine tools. The aim of high speed cutting processes is to achieve very high material removal rates. This means that the PK machine has to be driven close to the limit of its dynamic stability. Due to the non-serial structure of parallel kinematic machines and the complex nonlinear kinematic relations it is not possible to predict dynamic stability of the cutting process by conventional methods. Experience and research results gained with serial machines are often not valid for PK machines. At these machines, stiffness and flexibility highly depend on the pose of the tool in the workspace. As this also holds for the stiffness coupling of the degrees of freedom, both the natural frequencies and the corresponding mode shapes depend on the tool pose. This has to be considered when developing a method for predicting dynamically stable process parameters.
The aim of this project is the development of methods for predicting stability of cutting processes with PK machines. Therefore the dynamic behavior of different PK machines and the most important mechanisms of excitation depending on parameters like speed and temperature are investigated experimentally. At the same time we want to develop a software tool which helps the developer of a PK machine to predict the process stability depending on the process parameters rotation speed, feed rate and tool geometry, the geometry of the mechanism and of the pose of the tool in the workspace.
This project is a cooperation with the Institute for Machine Tools IfW of Prof. Heisel. All experimental work is carried out at the IfW, the simulation and software development takes place at the Institute of Engineering and Computational Mechanics.

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