Procedimiento para el análisis automatizado de la manufactura de la pieza de plástico y del molde de inyección

El proceso de manufactura mediante moldes de inyección de plástico es uno de los métodos de producción más versátiles y extendidos para la fabricación de piezas de plástico. Actualmente, existe una amplia variedad de software tipo CAD/CAE/CAM para el análisis y diseño asistido de piezas de plástico y moldes de inyección. Sin embargo, estas herramientas comerciales aún requieren de interacción humana y acceso a información geométrica interna de la pieza de plástico vinculada a su modelo CAD. La presente tesis doctoral propone una metodología universal basada en algoritmos automatizados de tipo geométrico – experto que, mediante el análisis de la geometría discreta de la pieza de plástico (malla en formato discreto definida por los elementos notables nodos y facetas), mejore y optimice el proceso actual de análisis, diseño y dimensionamiento del molde de inyección, sin recurrir a técnicas heurísticas e interacción manual por parte del usuario.Plastic injection molding is one of the most versatile and widespread manufacturing process for the plastic parts manufacture. Nowadays, there is a wide variety of CAD/CAE/CAM type software for the analysis and aided design of plastic parts and injection molds. However, these commercial tools still require human interaction and access to internal geometric information (geometric features) of the plastic part linked to their CAD model. The present PhD thesis proposes a universal methodology based on automated geometrical - expert algorithms that, by means of the analysis of the plastic part discrete geometry (mesh in discrete format defined by notable elements nodes and facets), improve and optimize the current analysis, design and dimensioning process of the injection mold, without resorting to heuristic techniques and manual interaction by the user.Tesis Univ. Jaén. Departamento Ingeniería Gráfica, Diseño y Proyectos. Leída el 3 de mayo de 2019

Fixture knowledge model development and implementation based on a functional design approach

The development of a knowledge model applied to fixture design is a complex task. The main purpose of such model is the development of a knowledge-based application to assist fixture designers. It comprises a detailed specification of the types and structures of data involved in the execution of the inference process needed to create a fixture solution for machining a raw part. A development method together with a knowledge model for automating fixture design is proposed. The development was divided into three parts: Design Process Model, definition of Top-level functional functions and Product Knowledge Model. Adopting a functional design approach, the fixture design solution was created in two levels: functional and detailed. The functional level is based on fixture functional elements and the detailed one is based on fixture commercial elements. The definitions and concepts used in the application are specified in several Units of Knowledge (UoK) that comprises the Fixture Knowledge Model. Common Knowledge Analysis and Design Structuring (CommonKADS), Methodology and software tools Oriented to KBE Applications (MOKA), Integrated DEFinition for Function Modelling (IDEF0) and Unified Modelling Language (UML) are the methodologies and techniques used in the proposed method. Finally, a prototype KBE application for fixture design was developed

Computing tool accessibility of polyhedral models for toolpath planning in multi-axis machining

This dissertation focuses on three new methods for calculating visibility and accessibility, which contribute directly to the precise planning of setup and toolpaths in a Computer Numerical Control (CNC) machining process. They include 1) an approximate visibility determination method; 2) an approximate accessibility determination method and 3) a hybrid visibility determination method with an innovative computation time reduction strategy. All three methods are intended for polyhedral models. First, visibility defines the directions of rays from which a surface of a 3D model is visible. Such can be used to guide machine tools that reach part surfaces in material removal processes. In this work, we present a new method that calculates visibility based on 2D slices of a polyhedron. Then we show how visibility results determine a set of feasible axes of rotation for a part. This method effectively reduces a 3D problem to a 2D one and is embarrassingly parallelizable in nature. It is an approximate method with controllable accuracy and resolution. The method’s time complexity is linear to both the number of polyhedron’s facets and number of slices. Lastly, due to representing visibility as geodesics, this method enables a quick visible region identification technique which can be used to locate the rough boundary of true visibility. Second, tool accessibility defines the directions of rays from which a surface of a 3D model is accessible by a machine tool (a tool’s body is included for collision avoidance). In this work, we present a method that computes a ball-end tool’s accessibility as visibility on the offset surface. The results contain all feasible orientations for a surface instead of a Boolean answer. Such visibility-to-accessibility conversion is also compatible with various kinds of facet-based visibility methods. Third, we introduce a hybrid method for near-exact visibility. It incorporates an exact visibility method and an approximate visibility method aiming to balance computation time and accuracy. The approximate method is used to divide the visibility space into three subspaces; the visibility of two of them are fully determined. The exact method is then used to determine the exact visibility boundary in the subspace whose visibility is undetermined. Since the exact method can be used alone to determine visibility, this method can be viewed as an efficiency improvement for it. Essentially, this method reduces the processing time for exact computation at the cost of introducing approximate computation overhead. It also provides control over the ratio of exact-approximate computation

Advances on Mechanics, Design Engineering and Manufacturing III

This open access book gathers contributions presented at the International Joint Conference on Mechanics, Design Engineering and Advanced Manufacturing (JCM 2020), held as a web conference on June 2–4, 2020. It reports on cutting-edge topics in product design and manufacturing, such as industrial methods for integrated product and process design; innovative design; and computer-aided design. Further topics covered include virtual simulation and reverse engineering; additive manufacturing; product manufacturing; engineering methods in medicine and education; representation techniques; and nautical, aeronautics and aerospace design and modeling. The book is organized into four main parts, reflecting the focus and primary themes of the conference. The contributions presented here not only provide researchers, engineers and experts in a range of industrial engineering subfields with extensive information to support their daily work; they are also intended to stimulate new research directions, advanced applications of the methods discussed and future interdisciplinary collaborations

Advances on Mechanics, Design Engineering and Manufacturing III

This open access book gathers contributions presented at the International Joint Conference on Mechanics, Design Engineering and Advanced Manufacturing (JCM 2020), held as a web conference on June 2–4, 2020. It reports on cutting-edge topics in product design and manufacturing, such as industrial methods for integrated product and process design; innovative design; and computer-aided design. Further topics covered include virtual simulation and reverse engineering; additive manufacturing; product manufacturing; engineering methods in medicine and education; representation techniques; and nautical, aeronautics and aerospace design and modeling. The book is organized into four main parts, reflecting the focus and primary themes of the conference. The contributions presented here not only provide researchers, engineers and experts in a range of industrial engineering subfields with extensive information to support their daily work; they are also intended to stimulate new research directions, advanced applications of the methods discussed and future interdisciplinary collaborations

An optimization method for the design of beads in long fiber reinforced polymer structures including the manufacturing process as an approach to realize methodically identified lightweight potentials = Eine Optimierungsmethode zur Gestaltung von Sicken in langfaserverstärkten Kunststoffstrukturen unter Berücksichtigung des Herstellungsprozesses als Ansatz zur Realisierung methodisch identifizierter Leichtbaupotentiale

Mobilitätssysteme befinden sich in einer Zeit des Umbruchs, da sich die Randbedingungen aus Politik und Gesellschaft gerade stark verändern. Im Fokus steht dabei, den Energie- und Ressourcenverbrauch sowie die CO2-Emissionen zu senken. Eine Möglichkeit diesen Herausforderungen zu begegnen, stellt der Leichtbau dar. Um die größtmögliche Gewichtsreduzierung erreichen zu können, ist eine konsequente Integration der Leichtbauaktivitäten in den gesamten Produktentstehungsprozess notwendig. Die vorliegende Arbeit liefert einen Beitrag zur Unterstützung des Produktentwicklers in verschiedenen Aktivitäten des Produktentstehungsprozesses, indem sie sich mit den Fragen „wie können Bauteile aus langfaserverstärkten Kunststoffen fasergerecht gestaltet werden“ und „wo sind diese in einem intelligenten Multi-Material Design (MMD) zielführend einzusetzen“ beschäftigt. Zur Frage „wie“ wird für die initiale Designfindung von versickten, langfaserverstärkten Bauteilen eine rechnergestützte, automatisierte Optimierungsmethode entwickelt. Bei diesem anisotropen Werkstoff ist es entscheidend, dass die aus dem Herstellungsprozess resultierenden Faserorientierungen im Bauteildesign berücksichtigt werden. Deshalb liegt der Optimierungsmethode eine iterative Kopplung von validierten Prozess- und Struktursimulationen zugrunde. Die Ergebnisse zeigen, dass die Berücksichtigung der lokal anisotropen Materialeigenschaften im Vergleich zu einer isotropen Materialmodellierung zu deutlich unterschiedlichen Designs führt. Um diese last- und fasergerecht designten Bauteile in einem MMD zielführend einsetzen zu können, ist jedoch zusätzlich die Frage nach dem „wo“ zu beantworten. Deshalb beschäftigt sich die Arbeit weiterhin mit der Entwicklung des funktionsbasierten Erweiterten Target Weighing Ansatzes (ETWA) zur komponentenübergreifenden Identifikation und Evaluation von Leichtbaupotentialen. Der ETWA unterstützt den Produktentwickler bei der Konzeptgenerierung in frühen Phasen des Produktentstehungsprozesses, in denen bereits ein Großteil des späteren Produktgewichts festgelegt wird. Dabei werden sowohl in der Analyse als auch in der Synthese die mit dem Gewicht und dessen Reduktion einhergehenden Kosten und CO2-Emissionen gemeinschaftlich betrachtet. Die Ergebnisse der mithilfe des ETWA im Rahmen dieser Arbeit entwickelten MMD eines Automobil-Federbeindoms und -Längsträgers zeigen das Potential der Methode auf. Die Kombination des ETWA und der fasergerechten Gestaltung versickter langfaserverstärkter Bauteile bietet eine methodische Unterstützung bei der Entwicklung von MMD insbesondere in frühen Phasen der Produktentstehung