Applied Mechanics and Materials Vol. 772

Abstract: The paper presents the model of a numerical milling module, expanding its capabilities with two controlled axes. Device through the use of adjustable-tilt construction of two mutually perpendicular rotary axes has free access to any part of the hemisphere. It is driven by stepper motors controlled with a computer through the special LPT driver and Step2CNC software.

Abstract: This paper presents some simulation based upon a dynamic model of a feed-drive within the structure of a CNC machine tool. A DC servomotor was considered as actuation device for the feed drive. For a given set of parameters for the position controller, two fuzzy types of fuzzy controllers were tested by means of simulation. The first fuzzy controller was a proportional one, with one input and one output, while the second one was a two variables one, with two inputs and one outputp.

Abstract: This paper presents theoretical research related to the determination of the chips shape when milling gears using flying hobbing cutter. This specific type of tool is used in research the cutting process case of hobbing cutter, in order to minimize the cost of research. It is presented also the structure of the flying hobbing cutter used in own research. In the end, some conclusions related to gears cutting process in case of hobbing are underlined.

Abstract: This paper presents experimental results for milling process using a six components dynamometer for complete mechanical actions measurement. The aim is the cutting moments determination and their evaluation on the milling cutter with multiple teeth during the cutting process. To know the cutting moments to the teeth of the tool, the instantaneous position of the teeth during milling process is determined. To achieve this purpose a calculation algorithm was developed to obtain the milling cutter teeth position respectively the moments at the tips of the teeth.

Abstract: It is very important and complexity to find the optimum values of wire EDM process parameters and contribution of each parameter to attain the better performance characteristics. In this study, an attempt has been made to optimize those parameters while machining the titanium alloy. Since the process involves more one than one response parameter, it is essential to carry out the multi-response optimization methodology .The experiments have been conducted with different levels of input factors such as pulse on time,pulse off time and wire tension based on Taguchi L₉ orthogonal table.Wire EDM optimal process parameter has been identified using grey relational analysis and significant parameter has been determined by analysis of variance. Experimental results have indicated that the multi-response characteristic such as material removal rate and surface roughness can be improved effectively through grey relational analysis.

Abstract: This paper describes direct cladding of magnesium (Mg) and aluminum (Al) alloys using a tandem horizontal twin roll caster that has three pairs of upper and lower rolls. Manufacturing conditions that are appropriate for fabricating Al/Mg and Al/Mg/Al cladded material were investigated. The surface condition of the cladded cast strip was examined. An electron probe micro analyzer was used to observe the interface between Al alloy and Mg alloy. The thickness of the mixed layer of Al and Mg alloy was 15μm, and how the materials were connected was clarified. Microscopic observation and backscattered electron analysis were used to investigate the cladding mechanisms of the Al and Mg alloy layers. Average hardness was determined using the Vickers hardness test at the Al layer and at the diffused layer between Mg and Al alloys. Cladding of Al/Mg alloy and A/Mg/Al alloy was possible using a tandem twin-roll caster. In addition, Al₃Mg₂ and Al₁₂Mg₁₇ phase precipitation at the interface of the Al and Mg alloys was confirmed during direct cladding from molten metals.

Abstract: In order to improve quality and productivity of polymeric composites production we suggest the technique of process simulation and optimization for large parts manufactured by compression molding. Optimal process design includes coupled heat transfer / thermo kinetic cure process formulation, its three-dimensional finite element model (FEM) implementation, its transient analysis at the parameterized thermal control law, and Pareto-based optimization, at which we determine control law parameters ensuring minimum standard deviations of the degree of cure within the cured body. We illustrate this approach via examples of two distinct cases of closed mould design concepts: one for moulds heated in autoclaves by the pressurized heated gas, which acts on the mould surface almost uniformly, and another for moulds with independently controlled built-in electrical heaters such as strip heaters or heated platens that are positioned along the length of the die at locations determined by structural features of the cured part. The suggested approach makes the process design more predictable, easier, faster, and more reliable. It can be adapted to specific manufacturing conditions and allows optimizing tools design and processing conditions before the mould and process control are made.

Abstract: Metal matrix composites (MMC's) have attracted the attention of researchers for quite some time. In the last 15 years, many studies have been reported in this field of MMC production through various routes. The most commonly used process for producing MMC is stir casting process whereby the reinforcement material is incorporated into the molten metal by stirring. It is a relatively low cost manufacturing process that is capable of producing high quality MMC. However, the process is associated with issues such as attaining uniform distribution of particles, wettability between particles and porosity in the MMCs. Because of these challenges, there has been continuous improvement in the process as well as the design of the furnace. In this research, an innovatively designed bottom tapping furnace has been used to produce the MMCs and the produced sample is characterized.

Abstract: This paper explores the possibility of tool wear classification in stone drilling. Wear model is based on Radial Basis Function Neural Network which links tool wear features extracted from motor drive current signals and acoustic emission signals with two wear levels – sharp and worn drill. Signals were measured during stone drilling under different cutting conditions, and then filtered before tool wear features extraction. Features were obtained from time and frequency domain. They have been analyzed individually and in combinations. The results indicate tool wear monitoring capacity of the proposed model in stone drilling, and its potential for simple and cost-effective integration with CNC machine tools.

Abstract: In this study, the influence of workrest positions on the deflection of a crankshaft is investigated, in order to enhance the machining precision in orbital grinding. Crankshafts of 3m, 5m and 8m are selected, and three types of states (no machining, journal machining and pin machining) are studied. The model is simplified with stiffnesses applied to the stock instead of real contact between workrest and stock. As the workrests are positioned to the machining region, the deflection of the machined stock is reduced. Pin machining shows more stable result than journal machining.