Nowadays, it is not uncommon to find news and research about robotic machining applications, as milling and drilling. The flexibility, programmability and low price of robots, conversely to CNC machines, makes robotic machining an interesting opportunity for manufacturing of large parts. In this paper, the authors show the current advances on developments of robotic machining and a theoretical framework of the process, evidencing its weaknesses and strengths. Since the low stiffness of robots is their main disadvantage, the target of researchers is to improve this characteristic, and therefore avoid adverse effects like vibration, which influences the machining accuracy. The last developments can be categorized according to their research field: modelling and control of the process, robot workspace optimization, redundancy analysis, vibrating/chatter analysis and new designs and methodologies for the improvement of machining. These researches increase the efficiency and accuracy of the process with the goal to convert robots in a real alternative to CNC machines. In fact, the authors are working on the aim of proposing a characterization of several machining operations with robots, considering a force/torque control that provide the system a feedback with the improved stiffness matrix to correct errors and improve the accuracy during machining.
At early design stages is where most part of the decisions and costs are compromised, and where 2D drawings are still widely used. The idea of using a single tool for the whole process, starting with the creation of a 3D model at early design stages has been profusely required in naval shipbuilding. It is not easy to convince the agents involved about the advantage of having an increased work at early phases although that will be largely reused downstream. This paper describes in detail the benefits of changing the process for minor warships design, by means of using an advanced CAD tool from the early stages and explaining the advantage in terms of quality and cost. The most remarkable benefits come from the data integrity and the avoidance of long design periods and cost increases due to errors, re-work and inconsistencies. The main challenges refer to the integration of all stages and disciplines, relying on the use of a single CAD tool that must be effective at all stages, including those in basic design such as the quick definition of the 3D model, as well as in the transfer of a simplified model to the analysis and calculation tools. This paper describes SENER findings in minor warships, as an example of engineering work, by means of an approach based on the use of FORAN, a shipbuilding oriented CAD System.
Many tools handle with the calculation of compartment definition, hydrostatics, intact and damage stability and power prediction, but these calculations are separated from the rest of ship CAD/CAM tools. Ship designers need to work closely with the shipyards, in a complex and distributed environment making necessary to have suitable tools at early design stages to ensure profitable projects. Naval architecture is handled in FORAN with a revolutionary approach, where integration and advanced features are the relevant characteristics in a single and complete set of applications that are used in conjunction to other disciplines, from concept design to operation. This new approach groups the former modules for naval architecture available in FORAN from many years, is intuitive and user-friendly. The information is stored in a database instead of a wide set of files. As regards this feature, there are two different alternatives depending on the scope of the project. If the ship designer wants to calculate only naval architecture calculations, the solutions is based on a SQLITE database suitable for a standalone application. This approach benefits a ship design office, in the study of different design alternatives very quickly but having a complete control of them. The other option is integrating the Naval Architecture with the rest of FORAN design disciplines, in a single database based in Oracle. In this case, the great benefit comes from the single truth of data from concept design to operation, which ensures dramatically the reduction of errors and re-work. After the definition of compartments in 3D, by using a very fast application, the module guides the user through the naval architecture calculations with a tree of elements very intuitive, with powerful key algorithms and with a solid representation of spaces. The definition of the necessary entities to make any kind of calculation is very fast. For the intact stability a set of standard stability criteria is provided. It is based in a quick definition of loading conditions, initial situations, flooding conditions and compartment subdivisions. And for the evaluation of the damage stability a set of standard stability criteria are also provided, following deterministic and probabilistic approaches. With these tools any naval architect is able to make very fast all the necessary studies to assure the stability regulations are complied with.
As a result of increased pressure to reduce cost and delivery times of modern ships and submarines, many shipyards are revising their processes and toolsets to optimize the management of sister ships. This article describes how a strong CAD-PLM integration with efficient functionality on the CAD side ensures better design and production in a multivessel context. To address this complex challenge, and after several years of experience in the development of the FORAN CAD/CAM system that is used in many important naval programs, SENER identified some remarkable assumptions to be considered:In a sister ships environment, each vessel or unit will have a CAD project,There will exist a class project to centralize the CAD locking and applicability data,The existence of an item in the CAD project is considered as an item occurrence in that project,Modifications on an item will be done from a single project, but all other projects sharing the item with the same applicability will also be locked to prevent modification on them by other users,Once the modification changes are applied, the CAD will update them in all projects sharing the items applicability (multisave concept),The use of applicability on an item within a sister ship series might be to all vessels (e.g., 1-UP), to all vessels newer than a specific one (e.g., 3-UP), to some vessels specifically (e.g., 1-UP), or to a combination of the above (e.g., 1-UP), and if no applicability is set, it means "effective for all vessels" (1-UP), andThe FORAN system already had functionality related to sister ships management in the past, but it has been notably improved with the complete FORAN-PLM integration. This article presents in detail the architecture of the applicability solution and the expected advantages and benefits for commercial and naval shipyards.
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