2,216 research outputs found
Unità mobili, attrezzate con apparecchiature a tecnologia avanzata di telecomunicazioni e telinformatica, atte a fornire prestazioni professionali e servizi specializzati in località minori disagiate
No full text"Unità multiservizi" atte a fornire, da un unico punto a disposizione del pubblico, con pagamento in moneta euro e con procedure semplificate e teleassistite da "unità centrale di controllo e teleassistenza", l'accesso on-line a servizi pubbllici informativi e con transazioni e l'accesso gratuito su linea telefonica a servizi di emergenza e di pubblica utilità.
No full textTool wear in cutting operations: experimental analysis and analytical models
No full textThe possibility of predicting the amount of the tool wear in machining processes is an interesting topic for industries, since tool wear affects surface integrity of the final parts and tool life is strictly connected with substitution policy and production costs. The definition of models able to correctly forecast the tool wear development is an important topic in the research field. For this reason in the present work, a comparison between response surface methodology (RSM) and artificial neural networks (ANNs) fitting techniques in tool wear forecasting was performed. For developing these predictive models, experimental values of tool wear, obtained by longitudinal turning operations with variable cutting parameters, were collected. Once selected, the best configuration of the two previously mentioned techniques, the resultant errors with respect to experimental data were estimated and then compared. The results showed that the developed models are able to predict the amount of wear. The comparison demonstrated that ANNs give better approximation than RSM in the prediction of the amount of the flank wear (VB) and of the crater wear (KT) depth. The obtained results are interesting not only from a scientific point of view but also for industries. In fact, it should be possible to implement the best model into a production manager software in order to correctly define the tool change during the lot production
Investigation and FEM-based simulation of tool wear in turning operations with uncoated carbide tools
No full textAlgorithm for Tool Geometry Updating in 3D FEM Environment Considering the Tool Wear
No full textRecent researches showed the possibility of simulating with good accuracy cutting operations by means of FEM software. Typically, cutting operations under orthogonal cutting conditions are considered since the corresponding 2D model allows low computational time. However, when actual cutting operations are considered 3D models must be utilized. This paper deals with tool wear simulation using 3D FEM software. The relevance of simulating tool wear is due to the possibility of studying the influence of process parameters, tool material, tool geometry and workpiece material on tool wear without performing expensive experiments. For this purpose, a subroutine for updating the tool geometry was implemented into Deform 3D FEM software. The developed subroutine estimates wear rates according to analytical wear models and modifies the tool geometry as the wear goes on. In order to improve the accuracy of tool wear simulations, three different tool areas, namely rake, flank and cutting edge, were considered and suitable wear models together with appropriate tool mesh nodes movement strategies were selected for every zone. Preliminary results showing the ability of forecasting tool wear are reported at the end of this paper
Multi-Step Tool Paths Development for Reducing Geometric Deviation and Pillow Effect in the Single-Point Incremental Forming
No full textSingle-point incremental forming (SPIF) process represents a good candidate in the Industry 4.0 panorama, whose paradigms of customized and small batch production require quick and cost-effective reconfigurations of manufacturing systems. SPIF enables the production of sheet components using simple equipment, consisting of a blank fixture and a hemispherical forming tool, without the need of dies. Despite its flexibility, this process presents springback-related drawbacks, which can limit its accuracy. Consequently, optimizing process parameters (such as feed rate, step-down size, and tool trajectory) is essential to mitigate these limitations. This study investigates how multi-step tool path strategies affect the geometric precision of walls and the occurrence of pillow defects during the incremental forming of AA1050 H24 aluminum alloy frustum cones. The findings from a comprehensive experimental campaign, which evaluated achievable geometry, applied loads, strain field, and thickness distribution, permitted the identification of best practices for improving the overall accuracy of the final product. As a result, a novel multi-step tool trajectory, concerning both a variable wall angle roughing phase and a finishing phase, has been identified as the optimal approach. This approach not only allows force reduction but also contributes to achieving a uniform thickness distribution. The results are encouraging, confirming the suitability of the proposed methodology and suggesting its diffusion at an industrial level
Postal de Claudio Vivas a Maruja Vieira, junio 23 de 1955
No full textPostal de Claudio Vivas a Maruja Vieira, felicitándola por el reconocimiento que le fue otorgado a la autora de poemasPostcard from Claudio Vivas to Maruja Vieira, congratulating her for the recognition given to the author of poems.Publicación, fondo Maruja Vieira, carpeta 1, folio
A multi-objective optimization workflow of ring-rolling process parameters based on production energy and time
No full textOur industrial era is characterized by a significant attention to environmental aspects and production sustainability. Under this point of view, the minimization of the process energy represents a milestone leading to a consistent reduction of pollution. However, to promptly react to the high production rate market request, companies employ time saving manufacturing strategies, often in contrast with this principle. Considering this, an optimization concerning the reduction of both production time and energy, results to be strategical, especially when energy-intensive processes, such as ring rolling, are considered. Ring rolling is a shaping process performed by a dedicated equipment, composed of a driving roll, an idle roll, and a couple of axial rolls, allowing to obtain seamless rings while simultaneously reducing their height and thickness, while enlarging diameter. The kinematics of each component of the equipment can be set independently. This leads to several process conditions influencing quality, energy, and times, and makes it difficult the selection of the most suitable configuration. In this paper, a multi-objective optimization workflow is presented. Starting from validated FEM simulation campaign results, the proposed methodology allowed to individuate the best process parameters combination for limiting energy and time, encouraging its application to a wider range of energy-consuming processes
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