I. Hüseyin Filiz

Dynamic optimization of multipass milling operations via geometric programming

Abstract This paper outlines the development of an optimization strategy to determine the optimum cutting parameters for multipass milling operations like plain milling and face milling. The developed strategy is based on the “maximum production rate” criterion and incorporates eight technological constraints. The optimum number of passes is determined via dynamic programming, and the optimal values of the cutting conditions are found based on the objective function developed for the typified criterion by using a non-linear programming technique called “geometric programming”. This paper also underlies the importance of using optimization strategies rather than handbook recommendations as well as pointing out the superiority of the multipass over the single-pass optimization approach.

Optimisation of process planning functions by genetic algorithms

This paper introduces optimisation modules of a process planning system called OPPS-PRI (Optimised Process Planning System for PRIsmatic parts) which has been developed together with its interfaces to provide a complete CAD/CAM integration. Primary objective of this work is to develop an intelligent and integrated CAD/CAM system for shop-floor use that can be used by an average operator and to produce globally optimised results (process plans and part programs). For this purpose, in this work, an attempt has been made to include the impact and potential of artificial intelligence (AI) in process planning applications and to optimise all events in an integrated CAD/CAM environment. GAs were extensively used in the development of process planning facilities and in the optimisation issues, in order to include profits of AI techniques into the system.

A note on the use of STEP for interfacing design to process planning

This short note demonstrates the use of standard for exchange of product data (STEP) for interfacing design to process planning via a compact feature recogniser. The methodology used in development of the interface (feature recogniser) makes use of both automatic feature-recognition and feature-based design technologies in order to combine their advantages, and the STEP for the non-problematic and full information exchange. Using the abilities of the STEP, a generic configuration scheme is developed in which the features are treated as a combination of faces to which geometrical and/or technical information is glued (associated). By this way, the designer is only forced to identify the functional parts of the features when designing the part, which may simplify the component design and result in the effective memory utilisation. The feature recogniser was implemented in C on a PC and tested on a large number of examples with positive results.

Allocating optimal index positions on tool magazines using genetic algorithms

This paper presents an optimisation system software developed for the determination of optimal index positions of cutting tools on the automatic tool changer (ATC) or turret magazine of CNC machine tools. Position selection is performed using a genetic algorithm (GA) which takes a list of cutting tools assigned to certain machining operations together with total number of index positions available on the ATC or turret magazines and, catalogue value of indexing time as the input, and then randomly generates an initial population of position sets (chromosomes). New chromosomes are generated using genetic operators: crossover, reproduction and mutation. A fitness function is used to evaluate the goodness of each chromosome in terms of total tool-indexing time. Based on the fitness values, the next generation is formed from the newly generated sequences and old population. As the iterations are continued, the better sequences with higher fitness values (lower total-indexing times) dominate and the system converges to an optimal positioning set. The system is implemented in C programming language and on a PC. It can be used as stand-alone system or as an integrated module of a process planning system called OPPS-PRI (Optimised Process Planning System for PRIsmatic parts) developed for prismatic parts.

Analysis of preloaded bearings under combined axial and radial loading

Abstract A practical method for the analysis of axially preloaded bearings under comiined loads is presented. The loads on each bearing which are mounted as the combinatio nof tandem and back-to-back or face-to-face arrangements are determined and the deflections and stiffnesses in axial and radial directions are calculated. The method is automated with an interative computer program and the results for some bearing assemblies are illustrated.

Experimental study on residual stresses in autofrettaged thick-walled high pressure cylinders

ABSTRACT Distribution of residual stresses on the wall of internally pressurized cylinders is one of the key factors in the design of thick-walled high pressure cylinders. Radial and tangential residual stresses induced by autofrettage process are measured by using X-ray diffraction method. Additionally, axial and tangential strains are measured in autofrettage tests to determine the strain changes with autofrettage pressures. Four different autofrettage pressure values are used in the tests. The numerical model is created in ANSYS® 15.0 Workbench and 2D axisymmetric analysis is performed for four levels of autofrettage pressures. Experimental and numerical results are found to be very close to each other, the tendency of changes in the distribution of residual stresses are the same and the strain measurements are very close to the numerical results.