Modul 1: Process planning#
With current state of the art process planning tools, undesired process-states like chatter, instabilities and deflections are in most cases observed for the first time when the process is already running. As a result, because of the extra time for achieving the desired product quality, high costs occur for the following reasons:
- Choosing too slow process parameters
- Adjusting the poor quality of the products in a secondary, often manually refurbishment processes
- Conducting a complete backward orientated loop with setting up a new process
In most cases, nobody actually understands which physical interrelations cause the problematic process-state with undesired vibrations. Hence, well working processes are never found. By providing the information on later occurring work pieces dynamics early in the planning phase, process optimisation can be executed right in the beginning with no high extra costs.
Therefore, in the DynaMill project the first module will be developed. By providing information about work pieces dynamics early in the planning phase, process optimisation can be done right in the beginning with no extra costs. With the results of the calculations being visualised, the cause of the problems gets obvious, so an optimal solution regarding process parameters, tools and clamping design can be found. This way machining of thin-walled work pieces gets fast, reliable and cost effective when the optimal process is set up right from the beginning. With state of the art finite element modelling (FEM) the dynamic behaviour of work pieces facing process excitations can be accurately calculated. The first challenge is to automatically combine the CAM simulation used in the process planning with net generators and 3D FEM modal analysis and to conduct the calculations in a time efficient way (see Figure 5). The second challenge is to predict the upcoming process excitation at any given instant of time. The combination of FEM based modal calculation and CAM process planning however provides the ability to lay up milling processes, which are dynamically stable any time, resulting in very productive processes with minimal work piece vibrations. Based on the simulation results, recommendations are deduced in a post processing module. These recommendations can include proper suited constant speeds, or if an agile spindle is available, CAM-paths including adaption of speed. Furthermore, if available, the setup adjustment of adaptive locator systems can be suggested. The development of agile spindle and adaptive locator system are part of DynaMill’s modules 2 and 3.
Schematic illustration of process planning module (Figure 5)
Objective of module 1: