Henri Paris

Modelling for process planning: the links between process planning entities

Abstract In an integrated design framework, each actor of the design process must have his own view of the product to efficiently participate and co-design. The product model used by the process planner is presented here: it is in fact extracted from the global product model of the whole design system by filtering. The links of dependence among the different entities of the model – links of availability, accessibility and quality – are particularly emphasised in this text. Their efficiency has been tested in process planning and product designing.

Modelling the vibratory drilling process to foresee cutting parameters

The poor removal of chips in deep drilling of small diameter is often the cause of tool breakage and poor quality surface. The vibratory drilling enables the chip to be split thanks to the axial vibrations of the drill self-maintained by the cutting energy. Therefore chips are then evacuated easily. A specific tool holder with a variable axial stiffness was developed by the authors. The amplitude of the vibrations is greater than the feed rate. Vibratory drilling has been modelled to predict the cutting conditions and the adjustment of the stiffness of the tool holder. The models and the performances of the self-excited vibratory drilling process were validated by an experimental study.

Integration of the Machining Point of View in the Product Modelling: The Fixturing Features

A fixturing feature model of a part is presented in this paper. United with the machining feature model and the corresponding positioning, it allows a process plan to be generated effectively. Geometrical parameters typical of a good locating or a good clamping and indicators typical of the part behaviour during machining are defined. The capacity for a fixturing feature to be an efficient clamping and an accurate locating is considered.

Assisting designers in the forecasting of surfaces used for easier fixturing in a machining process

Abstract Constraints concerning the manufacturing of product parts must be integrated as early as possible in the product-design process in order to reduce product costs. For this, a part of manufacturing knowledge must be at the designers disposal all through the design process. In order to facilitate the integration of machining facilities into a group of designers, computer tools have been developed by the research team: those tools have to assist the designers and be as close as possible to the tools they usually use. Here two types of tools are presented to solve this problem: the first integrates manufacturing tools in a computer-aided design environment and has already been developed in the authors laboratory, the second adds manufacturing constraints to the design process and is today under development in the laboratory. A computer module for determining machining fixturing of a part is given as an example of the first tool type. It manages both geometrical relationships and parameters and part and fixture behaviour. In the case of the second type, the information, that has to be fed back to the designer, is discussed.

Analytical modeling of thrust force and torque in drilling

The prediction of thrust force and torque in drilling remains a key issue. There are three main ways to determine these forces based on experimental, numerical and finally analytical approaches. The major drawback with numerical and analytical methods concerns their reliability compared to phenomenological models. As a consequence, several studies use a resetting method in order to correct parameters of their analytical or numerical models so that they correspond to experimental results. The goal of this article is to introduce a new analytical model in drilling based on the discretization of the cutting edge. Local forces are estimated with a semiorthogonal analytical model based on a modified Merchant’s model. Parameters have been identified by a basic semiorthogonal cutting test for a large range of cutting speed and feed rates, by friction tests for a range of sliding velocities and by a variable shear angle model. The macroscopic feed force and torque are estimated by the sum of each local force along the cutting edge. Two drills applied in a large range of cutting conditions are investigated to validate this approach.

Co-operation in design: indicators as supports for the discussion between product and process engineers

When designing a product, one needs to consider, as soon as possible, the constraints due to the different manufacturing domains through a co-operative work of the different actors of the design process. The co-operation of the product designer and the process planner aided by indicators of machinability is particularly emphasised in this communication. Therefore the negotiation between the two actors can be effective. Those indicators are not only analysis tools (like simulation) but also synthesis tools (predictive tools that propose new data and knowledge on the current definition of the part). In particular, some piece of geometry can be added to that definition proposed by the indicator. For instance, in the machining field, it can be surfaces able to efficiently fixture the part during machining. A minimal definition of the current part from which the process planner can add constraints due to his expert work is discussed. That definition is, among other things, based on skin and skeleton features.

Function modeling combined with physics-based reasoning for assessing design options and supporting innovative ideation

Abstract Functional modeling is an analytical approach to design problems that is widely taught in certain academic communities but not often used by practitioners. This approach can be applied in multiple ways to formalize the understanding of the systems, to support the synthesis of the design in the development of a new product, or to support the analysis and improvement of existing systems incrementally. The type of usage depends on the objectives that are targeted. The objectives can be categorized into two key groups: discovering a totally new solution, or improving an existing one. This article proposes to use the functional modeling approach to achieve three goals: to support the representation of physics-based reasoning, to use this physics-based reasoning to assess design options, and finally to support innovative ideation. The exemplification of the function-based approach is presented via a case study of a glue gun proposed for this Special Issue. A reverse engineering approach is applied, and the authors seek an incremental improvement of the solution. As the physics-based reasoning model presented in this article is heavily dependent on the quality of the functional model, the authors propose a general approach to limit the interpretability of the functional representations by mapping the functional vocabulary with elementary structural blocks derived from bond graph theory. The physics-based reasoning approach is supported by a mathematical framework that is summarized in the article. The physics-based reasoning model is used for discovering the limitations of solutions in the form of internal contradictions and guiding the design ideation effort.

Extraction of features for combined additive manufacturing and machining processes in a remanufacturing context

The emergence of additive manufacturing (AM) techniques in the last 30 years allows to build complex part by adding material in a layer-based fashion or spraying the material directly into the part or a substrate. Taking into account performance of these techniques in a ‘new remanufacturing strategy’ can open new ways to transform an end-of-life (EoL) part into a new part intended for another product. The strategy might allow a considerable material proportion of existing parts to be reused directly for producing new parts without passing through the recycling stage. In this work, the strategy enables the transformation of existing parts into desired parts is first presented. The strategy uses an adequate sequence of additive and subtractive operations, as well as inspection operations to achieve the geometry and quality of final parts. This sequence will be designed from a set of AM features and machining features, which are extracted from available technical information and the CAD models of existing part, and final part. The core of the paper focuses on the feature extraction approach. The approach development is based on the knowledge of AM processes and machining process, as well as the specifications of final part.

Water jet machining of MEDM tools

This contribution presents an investigation about the possibilities of using Water Jet (WJ) technology in combination with Micro Electrical Discharge Machining (MEDM) for tooling production in micro manufacturing. In the first phase the tool copper used in MEDM is produced by WJ machining. Afterwards, the final tool in steel is produced by MEDM. Such kinds of tools intend to be used in processes like hot embossing, molding, and other replication technologies in the field of micro manufacturing. The first results are very promising and the proposed tooling strategy, which involves besides MEDM also WJ technology, shows a lot of potential especially in the design and developing phase of micro-fluidic devices.

A product-model supporting coupling's management during microproduct design

Microproducts show specificities compared to macroproducts and their design processes differ. Nowadays, existing design tools manage microproduct specificities too late during the design process, only after the first product representation is available. This article presents a product-model able to represent microproducts during the design flow, taking into account their specificities and exceeding the limits of product representation in actual design tools. The genericity of this model is demonstrated by the instantiation of a micro electro mechanical system (MEMS) radio frequency (RF) switch.