Spiral Bevel Gears Face Roughness Prediction Produced by CNC End Milling Centers

The emergence of multitasking machines in the machine tool sector presents new opportunities for the machining of large size gears and short production series in these machines. However, the possibility of using standard tools in conventional machines for gears machining represents a technological challenge from the point of view of workpiece quality. Machining conditions in order to achieve both dimensional and surface quality requirements need to be determined. With these considerations in mind, computer numerical control (CNC) methods to provide useful tools for gear processing are studied. Thus, a model for the prediction of surface roughness obtained on the teeth surface of a machined spiral bevel gear in a multiprocess machine is presented. Machining strategies and optimal machining parameters were studied, and the roughness model is validated for 3 + 2 axes and 5 continuous axes machining strategies. Palabras claveThank you to the Department of Education, and to the Universities and Research program of the Basque Government for their financial support, by means of the ZABALDUZ program. We also thank the UFI in Mechanical Engineering department of the UPV/EHU for its support of this project

5-axis double-flank CNC machining of spiral bevel gears via custom-shaped milling tools -- Part I: modeling and simulation

A new category of 5-axis flank computer numerically controlled (CNC) machining, called \emph{double-flank}, is presented. Instead of using a predefined set of milling tools, we use the shape of the milling tool as a free parameter in our optimization-based approach and, for a given input free-form (NURBS) surface, compute a custom-shaped tool that admits highly-accurate machining. Aimed at curved narrow regions where the tool may have double tangential contact with the reference surface, like spiral bevel gears, the initial trajectory of the milling tool is estimated by fitting a ruled surface to the self-bisector of the reference surface. The shape of the tool and its motion then both undergo global optimization that seeks high approximation quality between the input free-form surface and its envelope approximation, fairness of the motion and the tool, and prevents overcutting. That is, our double-flank machining is meant for the semi-finishing stage and therefore the envelope of the motion is, by construction, penetration-free with the references surface. Our algorithm is validated by a commercial path-finding software and the prototype of the tool for a specific gear model is 3D printed.RYC-2017-22649 BERC 2014-201

Special Issue of the Manufacturing Engineering Society (MES)

This book derives from the Special Issue of the Manufacturing Engineering Society (MES) that was launched as a Special Issue of the journal Materials. The 48 contributions, published in this book, explore the evolution of traditional manufacturing models toward the new requirements of the Manufacturing Industry 4.0 and present cutting-edge advances in the field of Manufacturing Engineering focusing on additive manufacturing and 3D printing, advances and innovations in manufacturing processes, sustainable and green manufacturing, manufacturing systems (machines, equipment and tooling), metrology and quality in manufacturing, Industry 4.0, product lifecycle management (PLM) technologies, and production planning and risks

From 3D Models to 3D Prints: an Overview of the Processing Pipeline

Due to the wide diffusion of 3D printing technologies, geometric algorithms for Additive Manufacturing are being invented at an impressive speed. Each single step, in particular along the Process Planning pipeline, can now count on dozens of methods that prepare the 3D model for fabrication, while analysing and optimizing geometry and machine instructions for various objectives. This report provides a classification of this huge state of the art, and elicits the relation between each single algorithm and a list of desirable objectives during Process Planning. The objectives themselves are listed and discussed, along with possible needs for tradeoffs. Additive Manufacturing technologies are broadly categorized to explicitly relate classes of devices and supported features. Finally, this report offers an analysis of the state of the art while discussing open and challenging problems from both an academic and an industrial perspective.Comment: European Union (EU); Horizon 2020; H2020-FoF-2015; RIA - Research and Innovation action; Grant agreement N. 68044

Mechanical Engineering

The book substantially offers the latest progresses about the important topics of the "Mechanical Engineering" to readers. It includes twenty-eight excellent studies prepared using state-of-art methodologies by professional researchers from different countries. The sections in the book comprise of the following titles: power transmission system, manufacturing processes and system analysis, thermo-fluid systems, simulations and computer applications, and new approaches in mechanical engineering education and organization systems

Concept design of a fast sail assisted feeder container ship

A fast sail assisted feeder container ship concept has been developed for the 2020 container market in the South East Asian and Caribbean regions.The design presented has met the requirements of an initial economic study, with a cargo capacity of 1270 twenty-foot equivalent unit containers, meeting the predictions of container throughput derived from historical data. In determining suitable vessel dimensions, account has also been taken for port and berthing restrictions, and considering hydrodynamic performance. The vessel has been designed for a maximum speed of 25 knots, allowing it to meet the demand for trade whilst reducing the number of ships operating on the routes considered.The design development of the fast feeder concept has involved rigorous analyses in a number of areas to improve the robustness of the final design. Model testing has been key to the development of the concept, by increasing confidence in the final result. This is due to the fact that other analysis techniques are not always appropriate or accurate. Two hull forms have been developed to meet requirements whilst utilising different propulsor combinations. This has enabled evaluation of efficiency gains resulting from different hydrodynamic phenomena for each design. This includes an evaluation of the hydrodynamic performance when utilising the sail system. This has been done using a combination of model test results and data from regression analysis. The final propulsor chosen is a contra-rotating podded drive arrangement. Wind tunnel testing has been used to maximise the performance of a Multi-wing sail system by investigating the effects of wing spacing, stagger and sail-container interactions. This has led to an increase in lift coefficient of 32% from initial predictions. The savings in power requirement due to the sail system are lower than initially predicted. However, another benefit of their installation, motion damping, has been identified. Whilst this has not been fully investigated, additional fuel savings are possible as well as improved seakeeping performance.The design is shown to be environmentally sustainable when compared to existing vessels operating on the proposed routes. This is largely due to the use of low-carbon and zero-sulphur fuel (liquefied natural gas) and improvements in efficiency regarding operation. This especially relates to cargo handling and scheduling. Green house gas emissions have been predicted to fall by 42% and 40% in the two regions should the design be adopted. These savings are also due to the use of the Multi-wing sail system, which contributes to reductions in power requirement of up to 6% when the vessel operates at its lower speed of 15 knots. It is demonstrated that the fast feeder is also economically feasible, with predicted daily cost savings of 27% and 33% in the South East Asian and Caribbean regions respectively. Thus the fast feeder container ship concept is a viable solution for the future of container transhipment. <br/

Feature based workshop oriented NC planning for asymmetric rotational parts

This thesis describes research which is aimed at devising a framework for a feature based workshop oriented NC planning. The principal objective of this thesis is to utilize a feature based method which can rationalize and enhance part description and in particular part planning and programming on the shop-floor. This work has been done taking into account new developments in the area of shop floor programming. The importance of the techniques and conventions which are addressed in this thesis stems from the recognition that the most effective way to improve and enhance part description is to capture the intent of the engineering drawing by devising a medium in which the recurring patterns of turned components can be modelled for machining. Experimental application software which allows the user to describe the workpiece and subsequently generate the manufacturing code has been realized