Catálogo de publicaciones - libros

The dimensional and geometrical tolerancing of machine elements is an important step in the design and manufacturing of a product. Unfortunately, tolerancing takes place late in the current design processes. Generally, it is only in the detail drawings of the parts that the tolerances are determined qualitatively and quantitatively. Some design problems appear which could have been detected upstream if the tolerances had been introduced from the very start. In the proposed design process, the mechanism is defined from a minimal kinematics structure to a detailed geometry. The tolerancing method is directly integrated into this design process. There is an inevitable growing complexity of the mechanical structure. Some technical choices are carried out at each level and it would be interesting to evaluate their geometrical influence on the expressed conditions. Therefore, we propose to deal with the problem of tolerance in an integrated manner with the process of design. The recursive top-down design and tolerancing process is general. The different design solutions, and technological choices, directly influence the dimensional and geometrical tolerances. We present a graph tool, which allows definition of the topology of the mechanism, during all phases of its design. The tolerancing graph is translated into ISO standards conforming tolerances. Different views are possible depending on the detail level needed by the designer. During the design process, the graph is simultaneously updated. An example is studied with the different steps to illustrate this integrated method. The influence of different possible design solutions on the tolerances is compared in order to validate these choices.

The elementary design model “Contact and Channel Model” (C&CM) is a new approach to the treatment of technical systems. It connects the abstract level of the function of a technical system with the detailed level of the system’s real shape. This connection is generated by the description of the areas relevant to the function of the system: the Working Surface Pairs and the Channel and Support Structures linking them. Basic hypotheses concerning C&CM are described in []. They define the connections between a pair of working surfaces and their linking channel and support structure. Two important hypotheses are that functions can only be generated in Working Surface Pairs and that the fulfilment of any technical function needs at least two Working Surface Pairs and a connecting Channel and Support Structure. In this paper, these two basic hypotheses are validated and explained by means of technical examples.

Designers in every industry from automotive, aerospace and telecommunications to medical equipments and biomedical artifacts strive to enhance the product design efficiency in order to cope with changing demands, while delivering higher quality products with shorter lead time and for less cost. Effective integration of the product design and process planning can improve manufacturability and maximize satisfaction of the designer’s intent. This paper presents a Design For Machining (DFM) tool that enables designers to the estimate effect of the design decisions on the accuracy of the machined product, particularly those containing sculptured surfaces. Actual variations of machined features can be predicted using the proposed analytical method. The comparison of these variations with the nominal allocated tolerances identifies critical portions of the design where unacceptable deviations may occur after machining. Constraints may be imposed on the design space to take into consideration the manufacturing limitations, increase parts acceptance and reduce scrap and rework. The designers can use these results to guide or drive the product design either by changing the design geometry or by modifying the specified design tolerances. The developed method is applicable to any geometry and is particularly useful and efficient for designing accurate sculptured surfaces. A sculptured surface auto-part is used for illustration.

Worth is assessed throughout the Life Cycle. Then we consider a trade-off between Worth, Cost, and Time. This methodology concerns the selection of design solutions from thousands of combinations of design parameters. The current DfX is considered extended, and so the proposed methodology is called Extended DfX. This methodology is applied to digital consumer product development. The worth of digital consumer products is especially important, but Worth is not always equivalent to performance, whereas it usually is in the case of other products. Therefore, a novel approach is required for assessing Worth in digital consumer products development.

The design process of machine tools is regarded as a sequential, discrete and inefficient process, as it requires various kinds of design tools and many working hours. This paper describes an integrated design system, embedding a design methodology that can support systematically the structural design and analysis of machine tools. The system is a knowledge-based design system and has three machine-tool-specific functional modules, including: configuration design and analysis, structural element design, and structural analysis support module. A machine configuration appropriate for design requirements is selected using the configuration design and analysis module. The arrangement of ribs for each structural part is then decided in the structural element design module. The structural analysis support module converts the design result into script file which is used to evaluate the designed structure by utilizing FEA software “ANSYS.” The system is applied to the design of a tapping machine, and shows that the machine structure can be designed quickly and conveniently with minimum dependency on the capability of a design engineer.

This paper presents the design of a control process that intelligently manages and unifies the reconfigured operations of individual manufacturing physical systems like robotic and CNC systems. The goal is to develop a Unified, Reconfigurable Open Control Architecture (UROCA) system that represents a control level higher than the open architecture controllers but utilizes their powerful features. The unifying architecture UROCA is designed based on a new controller approach inspired by the concept of human’s left/right brain and whole brain intelligence, which assures traceability between the requirements and capabilities of the controller and a high degree of operational flexibility. The UROCA design process follows the guidelines of a methodology called the Design Approach for Real-Time Systems (DARTS). This DARTS method proceeds from and builds on the application results of a specification methodology called Real-Time Structured Analysis (RTSA). The outcome of this design is a three-layer (bidirectional) hierarchical control architecture having deliberative left brain for normal operations and reactive right brain for contingent operations or navigation control. A third hybrid mode is also enabled.