15,535 research outputs found
Topological model for machining of parts with complex shapes
Complex shapes are widely used to design products in several industries such
as aeronautics, automotive and domestic appliances. Several variations of their
curvatures and orientations generate difficulties during their manufacturing or
the machining of dies used in moulding, injection and forging. Analysis of
several parts highlights two levels of difficulties between three types of
shapes: prismatic parts with simple geometrical shapes, aeronautic structure
parts composed of several shallow pockets and forging dies composed of several
deep cavities which often contain protrusions. This paper mainly concerns High
Speed Machining (HSM) of these dies which represent the highest complexity
level because of the shapes' geometry and their topology. Five axes HSM is
generally required for such complex shaped parts but 3 axes machining can be
sufficient for dies. Evolutions in HSM CAM software and machine tools lead to
an important increase in time for machining preparation. Analysis stages of the
CAD model particularly induce this time increase which is required for a wise
choice of cutting tools and machining strategies. Assistance modules for
prismatic parts machining features identification in CAD models are widely
implemented in CAM software. In spite of the last CAM evolutions, these kinds
of CAM modules are undeveloped for aeronautical structure parts and forging
dies. Development of new CAM modules for the extraction of relevant machining
areas as well as the definition of the topological relations between these
areas must make it possible for the machining assistant to reduce the machining
preparation time. In this paper, a model developed for the description of
complex shape parts topology is presented. It is based on machining areas
extracted for the construction of geometrical features starting from CAD models
of the parts. As topology is described in order to assist machining assistant
during machining process generation, the difficulties associated with tasks he
carried out are analyzed at first. The topological model presented after is
based on the basic geometrical features extracted. Topological relations which
represent the framework of the model are defined between the basic geometrical
features which are gathered afterwards in macro-features. Approach used for the
identification of these macro-features is also presented in this paper.
Detailed application on the construction of the topological model of forging
dies is presented in the last part of the paper
Extracting, managing, and exploiting the semantics of mechanical CAD models in assembly tasks
The manufacturing of mechanical products is increasingly assisted by technologies that exploit the CAD model of the final assembly to address complex tasks in an automated and simplified way, to reduce development time and costs. However, it is proven that industrial CAD models are heterogeneous objects, involving different design conventions, providing geometric data on parts but often lacking explicit semantic information on their functionalities. As a consequence, existing approaches are mainly mathematics-based or need expert intervention to interpret assembly components, and this is limiting.
The work presented in the thesis is placed in this context and aims at automatically extracting and leveraging in industrial applications high-level semantic information from B-rep models of mechanical products in standard format (e.g. STEP). This makes possible the development of promising knowledge intensive processes that take into account the engineering meaning of the parts and their relationships.
The guiding idea is to define a rule-based approach that matches the shape features, the dimensional relations, and the mounting schemes strictly governing real mechanical assemblies with the geometric and topological properties that can be retrieved in CAD models of assemblies. More in practice, a standalone system is implemented which carries out two distinct operations, namely the data extraction and the data exploitation. The first involves all the steps necessary to process and analyze the geometric objects representing the parts of the assembly to infer their engineering meaning. It returns an enriched product model representation based on a new data structure, denoted as liaison, containing all the extracted information.
The new product model representation, then, stands at the basis of the data exploitation phase, where assembly tasks, such as subassembly identification, assembly planning, and design for assembly, are addressed in a more effective way
Interface between SysML and Sequence Planner Language for Formal Verification
This paper presents a method and software for interfacing Systems Modeling Language (SysML) and Sequence Planner Language (SPL). Exchange of information between different software tools is of major interest for modern manufacturing industries from early design to final implementation. SysML, with its structure as a common platform, can then be interfaced with other domain-specific modeling tools to achieve information exchange. This paper presents a method to interface SysML with a recently introduced language for operation sequences called Sequence Planner Language (SPL). By this method, necessary information from behavioral constructs of SysML model are extracted and structured in SPL. This language, being a formal, graphical language,can be used to formally verify the system for any blocking states. An academic and an industrial model developed in SysML are tested using the interface implementation and the results show that information from SysML can be visualized in SPL and formally verified to have no blocking states
Enhancement of Transparency and Adaptability by Online Tracking of Enterprise Processes
Enterprises are seeking novel approaches to reduce cost in complying with regulations and requirements from original equipment manufacturers. Consequently, enterprises are investing in manufacturing execution system (MES) solutions for realizing these requirements. However, most of the MES solutions do not support processing of real-time process data acquired from shop floor for online monitoring and control of enterprise processes. Further, monitoring of enterprise processes can be classified into online tracking and passive tracing. In the contribution, a framework is envisaged for online tracking of enterprise processes based on MES concepts. This framework has been validated in an industrial scenario
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