Simulation of machining processes

Not only in the era of „industry 4.0“, process simulations and the coupling between process models and the real manufacturing process become more and more important. In current research projects, methods for analyzing processes with geometrically defined and undefined cutting edges are developed (fig.). This work is not focused on modelling the chip formation, but on investigating more efficient models for predicting and analyzing the machining of complex parts.

Fig.: Application of process simulations

The simulation system is based on the geometric description of the tool, the workpiece, and the resulting material removal process. By analyzing the uncut chip and using an empirical force model, the characteristic process forces can be determined. In order to describe, e.g., the resulting process vibrations during the machining process, models based on modal parameters (modal mass, damping, and eigenfrequency) are used. Therewith, the dynamic behavior of the tool, workpiece, clamping system, and machine tool can be taken into account.

Additionally to the analysis of the whole machining process or of process chains (e.g. milling and subsequent finishing), the engagement situation directly at the cutting edge can be modelled and the resulting surface structures can be determined. This offers a possibility; to analyze the influence of different process parameter values on the machined workpiece surface. For machining processes with geometrically undefined cutting edges, e.g., grinding or microfinishing, the modeling of the individual grains and their process behavior is a particular challenge.

Process simulations can also be used during the design phase of, e.g., fixture systems or machine tools. Usually, finite element systems are applied to calculate the static and dynamic load, but a prediction of the prospective performance of the designed components during the machining process is not possible. For this purpose, process simulations can additionally be used in order to evaluate the process forces and, based on this, to avoid an over- or undersizing of the designed components.

In additional research projects, the coupling of sensors (analysis of the current state) and process simulations (prediction of prospective states) as well as the qualification of the simulation for the applicability during the adaptation planning of factory systems are investigated.

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