Optimization of 5-Axis milling processes based on the process models with application to airfoil machining

5-axis milling is widely used in machining of complex surfaces such as airfoils. Improper selection of machining parameters may cause low productivity and undesired results during machining. There are several constraints such as available power and torque, chatter stability, tool breakage etc. In order to respect such constraints proper machining parameters should be determined. In this paper, methodologies for improving 5-axis milling processes are presented. Selection of machining parameters is performed using process simulations. The developed methodologies are presented on an example airfoil

Computing axes of rotation for 4-axis CNC milling machine by calculating global visibility map from slice geometry

This thesis presents a new method to compute a global visibility map (GVM) in order to determine feasible axes of rotation for 4-axis CNC machining. The choice of the 4th-axis is very important because it directly determines the critical manufacturing components; visibility, accessibility and machinability of the part. As opposed to the considerable work in GVM computation, this thesis proposes an innovative approximation approach to compute GVM by utilizing slice geometry. One advantage of the method is that it is feature-free, thus avoiding feature extraction and identification. In addition, the method is computationally efficient, and can be easily parallelized in order to vastly increase speed. In this thesis, we further present a full implementation of the approach as a critical function in an automated process planning system for rapid prototyping

Optimization of complex cutting tools using a multi-dexel based material removal simulation

Multi-dexel based material removal simulations provide a fast and flexible way to compute process forces and tool deflections for milling and turning operations. This allows an advanced process planning including detection of collisions for complex toolpaths. However, using dexel simulations for designing cutting tools has rarely been investigated. Especially the position of individual cutting edges is not considered, because current approaches only subtract the sweep volume of the tool envelop instead of the rake face. This paper presents a new method to design cutting tools using material removal simulations and a detailed tool geometry representation. The discretization of the tool allows an efficient calculation of the engagement conditions of individual cutting edges. The method is used to optimize novel porcupine milling cutters with round indexeble inserts, which produces a geometry analogous to serrated end mills. Based on the calculated forces, the positions of individual indexable inserts are adjusted to minimize the maximum radial force. An optimum has been found that reduces radial force by 12% compared to conventional porcupine milling cutters with squared inserts. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of The 17th CIRP Conference on Modelling of Machining Operation

Incident laser modulation by tool marks on micro-milled KDP crystal surface: Numerical simulation and experimental verification

© 2019 Elsevier Ltd Micro-milling has been accepted as the most promising method to repair the micro-defects on the surface of KH2PO4 (KDP) optics. However, surface tool marks are inevitably introduced during the micro-milling repairing process, and could possess great potential risks in lowering the laser-induced damage threshold of KDP optics. The primary cause of laser damage growth of nonlinear crystals has been considered as its internal light intensification. In this work, how the tool marks impact the incident laser modulation as well as the laser-induced damage resistance of micro-milled KDP optics was theoretically and experimentally investigated. The results indicate that periodic tool marks can cause diffraction effect and result in significant relative light intensity modulation (IRmax), up to 5.6 times higher than that inside smooth crystal surfaces. Although the change trends of IRmax with respect to tool marks on both surfaces of KDP optics are similar, the IRmax induced by the rear-surface tool marks is nearly twice higher than that induced by the front-surface tool marks, which means the rear surface with tool marks are more vulnerable to be damaged. The period of tool marks determines the modulation degree and distribution patterns of light intensity inside KDP crystal while the residual height of tool marks can only slightly regulate the modulation degree of light intensity. The tool marks with a period of 1 μm normally give rise to serious light intensification and should be strictly excluded, while the period of tool marks from 10 μm to 20 μm is conducive to the laser damage resistance of micro-milled KDP optics, which were verified by the tests of transmittance capacity and laser damage resistance, and is supposed to be preferred in the actual repairing process of full-aperture KDP optics

IMECE2002-33598 CONFIGURATION-SPACE SEARCHING AND OPTIMIZING TOOL ORIENTATIONS FOR 5-AXIS MACHINING

ABSTRACT This paper presents a methodology and algorithms of optimizing and smoothing the tool orientation control for 5-axis sculptured surface machining. A searching method in the machining configuration space (C-space) is proposed to find the optimal tool orientation by considering the local gouging, rear gouging and global tool collision in machining. Based on the machined surface error analysis, a boundary search method is developed first to find a set of feasible tool orientations in the Cspace to eliminate gouging and collision. By using the minimum cusp height as the objective function, we first determine the locally optimal tool orientation in the C-space to minimize the machined surface error. Considering the adjacent part geometry and the alternative feasible tool orientations in the C-space, tool orientations are then globally optimized and smoothed to minimize the dramatic change of tool orientation during machining. The developed method can be used to automate the planning and programming of tool path generation for high performance 5-axis sculptured surface machining. Computer implementation and examples are also provided in the paper