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Konstruktionsregeln für additive Fertigungsverfahren
Abstract
Additive Fertigungsverfahren stellen Bauteile und Baugruppen aus Kunststoff- oder Metallwerkstoffen schicht¬weise, ohne formgebendes Werkzeug her. Daraus resultierende Gestaltungsmöglichkeiten schaffen einen großen Nutzen für Anwender dieser Technologie. Um diesen Nutzen einem breiten An-wenderkreis zugänglich zu machen, werden im Projekt „Direct Manufacturing Design Rules“ (DMDR) Konstruktionsregeln für Additive Fertigungsverfahren erarbeitet. Hierzu wird zunächst eine verfahrens-unabhängige Methode zur Erarbeitung der Konstruktionsregeln entwickelt. Diese ermöglicht die Erar-beitung von Konstruktionsregeln, die zunächst für die hier betrachteten Additiven Fertigungsverfahren und Werkstoffe gelten. Die Ergebnisse werden in einem Konstruktionsregelkatalog zusammengefasst.
... Concerning freedom of design, complex parts like undercuts, variable wall thicknesses, cavities, lattice or bionic structures, as well as integrated cooling systems are nowadays state of the art. Since single parts with a high level of complexity and degree of customization are feasible, the higher manufacturing costs of AM can be accepted [8][9][10][11][12]. Concerning this, the full capacity of AM can be exploited by applying finite element methods during the design phase, since they are suitable within the conception stage for any part. ...
... For that, several design guidelines must be taken into account. [8][9][10][11][12]. Of all the metal AM processes, selective laser melting (SLM) is the most widespread. ...
The production of small to medium-size aluminum gearbox housings at large quantities and high rates is commonly carried out by die casting. The manufactured parts are characterized by a very good surface finish and dimensional accuracy. However, a certain amount of gas porosity and shrinkage holes are to be expected. Since defects affect the mechanical properties of the housing, their reduction is also a main goal in the enhancement of the process. Improved material properties lead to higher strength and better gear performance. Despite die casting being cheap in comparison to sand casting, the costs of the casting equipment, whose main components are two hardened steel dies with the desired shape, are very high. Based on one particular gearbox housing, the objective of the present development project was to improve the quality of the gearbox housing by reducing its casting defects, while achieving simultaneously an overall improvement of the casting process. To this end, a new kind of die with integrated cooling channels was designed and evaluated using additive manufacturing technologies. First, the usual defects like cold casting sprue, sticking due to overheating, and solidification cavities of the cast part as well as the cooling behavior of the standard die were analyzed. Thus, the areas to be cooled down in a controlled way were identified and the corresponding cooling system was developed. Afterwards, an FEM analysis was carried out to check the die’s integrity during the casting process. The model was built according to given operating conditions. The stress analysis was efficiently studied on a variety of cooling channel designs. The results led to new and improved knowledge concerning the die’s stability. 3D metal printing was suitable for the manufacturing, because a clear additional benefit compared to the standard die was expected. Selective laser melting (SLM) was chosen because this technology allows the cooling system to be printed without a supporting structure. The material chosen was the tool steel 1.2709 (X3NiCoMoTi18-9-5). The die was printed and machined to its final dimensions using this material. Finally, the die casting mold was assembled and 15,000 casting rounds were executed by varying the temperature of the cooling oil. The type, number, and distribution of failures of the cast parts as well as the cycle duration were analyzed. As a result of the present work, the quality of the gearbox housing was improved concerning porosity and shrinkage holes. Furthermore, due to the targeted solidification, the casting process was shortened by about 11% per casting cycle.
... Dabei sind diese jedoch zumeist auf einzelne Bauteile beschränkt und nicht ohne weiteres auf Baugruppen übertragbar. [3,6,7,10] Die Gestaltung beweglicher Baugruppen wird im Wesentlichen davon bestimmt, ob diese im Gesamten als Baugruppe oder die einzelnen Bauteile getrennt gefertigt werden und somit einen zusätzlichen Montageschritt erfordern (siehe Abb. 1). [7]. ...
Additive Fertigungsverfahren haben sich aufgrund ihrer losgrößenunabhängigen Fertigungskosten und der großen Gestaltungsfreiheit sowohl in der Forschung als auch in der industriellen Anwendung erfolgreich etabliert. So werden die verschiedenen additiven Verfahren nicht mehr nur für die Herstellung von Prototypen, sondern vermehrt zur Fertigung komplexer, endkonturnaher Bauteile und gesamter Baugruppen angewendet. Dabei konnten in den letzten Jahren zahlreiche Richtlinien für die Gestaltung der schichtweise aufgebauten Bauteile hergeleitet werden. Eine umfassende Betrachtung additiv gefertigter Gelenke fehlt jedoch bisher. Um den Produktentwickler bzw. Konstrukteur bei der Gestaltung von mittels Fused Deposition Modeling (FDM) hergestellten Drehgelenken zu unterstützen, werden im nachfolgenden Beitrag relevante Aspekte, wie z. B erforderliche Mindestspalte zur Trennung von nicht- und einfach-gekrümmten Elementen, aufgezeigt. Versuchsergebnisse dienen dabei als Basis für die Ableitung von Richtlinien für das Design FDM-gedruckter Gelenke und ergänzen dadurch die Grundsätze des Design for Additive Manufacturing. Die Umsetzung der erarbeiteten Gestaltungsrichtlinien wird anschließend exemplarisch an einem ebenen Mechanismus dargelegt.
... The LV participants were asked to mark those predefined aspects, which have to be considered for design and production planning of AM parts in some or all AM technologies; results of this multiple-choice question are displayed in Fig. 6. The predefined aspects are based on [1,8,11] and contain four supplementary wrong answers of production-ready design for other manufacturing technologies. ...
Technological advancements in additive manufacturing (AM) has enabled the usage of AM for end-use parts more than ever before. Deciding whether or not to apply AM for final parts and knowing how to design for AM is fundamental in the design phase, which is why Design for AM (DfAM) methods are currently being elaborated.
... Moreover, temperature distributions during the manufacturing process lead to thermal distortion and therefore material accumulation as well as abrupt thickness changes have to be avoided. [24][25][26] To sum up, new process-specific design rules are necessary to use the possibilities of the innovative manufacturing technology. These rules have to be considered early in the product development process, in addition to appropriate process-specific computations. ...
The additive manufacturing (AM) model factory's aim is to establish a leading-edge learning academy for the digital and generative production of innovative mechatronic products, where the complete value chain is integrated on a single site. Short courses and deep dives enable easier access to the state of the art technologies and increase the awareness for their potentials. Anchored in key industries such as automotive, aerospace, and medical by major OEMs and regional SMEs, the AM model factory cooperates with world-class partners and leading market players. This paper displays the model factory's setup, selected technologies, exemplary courses, and benefits.
The construction of gearbox housings is severely restricted by all the currently used machining processes. 3D metal printing opens up new possibilities in this area. However, a clear additional benefit compared to the standard cast housing must be given, in order to make additive manufacturing viable. The objective of the present project was to research both the potential and restrictions of additive manufacturing technologies regarding the design of gearbox housings. As a result of this investigation, a topology optimized lightweight gearbox housing with integrated oil channels and scraper was obtained. The topology optimization process of the new gearbox was carried out in two work steps. The first consisted of the determination and design of the primary load-bearing structure of the housing. Therefore, an iterative design process was needed in order to develop the final support structure, because the topology optimization only provides a design draft of the framework structure. Concerning the iteration, an FEM analysis was performed to check and improve the draft after each loop. During the evaluation, safety and weight were compared with the previous version. During the second step of the topology optimization, the structure of all the oil channels was developed, creating a morphological box. Finally, the new gearbox housing was generated by combining the topology optimization with the concepts from the morphological box. Selective Laser Melting (SLM) was chosen for manufacturing because it allows the printing of components of the desired dimension with the required accuracy. The developed gearbox prototype was printed using the aluminum alloy AlSi10Mg (A360). Due to the flexibility of the SLM technology, it was possible to fulfill all specific design criteria while also showing the typical topology-optimized structure too. Afterwards, the housing was machined to achieve precise dimensions and tolerances. Finally, the gearbox was assembled, and both its mechanical integrity and the functionality of the integrated oil systems were fully checked with short-term tests.
Bright white light sources are of significant importance for automotive front lighting systems. Todays upper class vehicles mainly use HID or LED as light source. As a further step in this development laser diode based systems offer high luminance, efficiency and allow the realization of new styling concepts and new dynamic lighting functions. These white laser diode systems can either be realized by mixing different spectral sources or by combining diodes with specific phosphors. Based on the approach of generating light using a laser and remote phosphor, lighting modules are manufactured. Four blue laser diodes (450 nm) are used to activate a phosphor coating and thus to achieve white light. A segmented paraboloid reflector generates the desired light distribution for an additional car headlamp. We use high speed milling and selective laser melting to build the reflector system for this lighting module. We compare the spectral reflection grade of these materials. Furthermore the generated modules are analyzed regarding their efficiency and light distribution. The use of Rapid Prototyping technologies allows an early validation of the chosen concept and is supposed to reduce cost and time in the product development process significantly. Therefor we discuss costs and times of the applied manufacturing technologies.
Purpose
– This paper aims to present a methodology to help end-users to find appropriate part candidates for the use of the additive manufacturing (AM) technology. These shall be capable of bringing AM into their businesses. The concept furthermore includes approaches for redesigning current available parts and helps to estimate the economic implications of the use of the technology.
Design/methodology/approach
– The approach starts to discuss general economic aspects for the successful use of AM. While describing the introduction of new technologies into existing businesses, the importance of an appropriate part selection for AM is pointed out. A methodology for a part selection process is presented, and the different criteria are developed. An approach for a redesign of the selected parts, including the gathering of requirements, is given based on different sample parts. A variation of criteria to include measures for product piracy is highlighted.
Findings
– The methodology has proven applicability in several research and industry projects in aerospace applications. Independent part selections from experts analyzed within a project of the European Space Agency had a 90 per cent overlap with the results. It allows companies with only basic AM knowledge to start a part screening for applicable AM candidates in their own company with a reasonable effort.
Originality/value
– The methodology for the redesign process helps to identify the main functions of the products targeted and the relevant environment, so one can benefit from the various advantages that AM has to offer. The selection methodology helps to ask the right questions and to reduce the effort.
Das bewährte und international anerkannte Lehr- und Handbuch für Studium und Praxis vermittelt die methodischen Grundlagen der Konstruktionslehre als Voraussetzung einer erfolgreichen Produktentwicklung. Dieses bisher in acht Sprachen übersetzte Standardwerk hat seinen festen Platz bei Studenten sowie Entwicklern und Konstrukteuren in der Praxis gefunden. Jede Neuauflage aktualisiert, ordnet und strafft die wissenschaftlichen Grundlagen und erweitert die dargestellten Themen um aktuelle Sachverhalte, ohne kurzlebigen Trends zu folgen.
Die vorliegende 7. Auflage
• gibt einen aktuellen Überblick über Methoden und Werkzeuge der Produktplanung,
• stellt neue, erfolgreich eingesetzte Ansätze zur Generierung neuer Produktideen dar,
• fasst die TRIZ-Methodik zur Lösungsfindung zusammen,
• zeigt, wie diese zur Anforderungsermittlung genutzt werden kann,
• beschreibt die Product-Lifecycle-Management-Strategie zur nachhaltigen Produktentwicklung und
• stellt Produktdatenmanagement-Systeme (PDMS) als rechnerbasiertes Werkzeug zu deren Umsetzung vor.
Rapid prototyping generally refers to techniques that produce shaped parts by gradual creation or addition of solid material, therein differing fundamentally from forming and material removal manufacturing techniques. This paper tries to summarise one decade of research and developments in rapid prototyping. The first part surveys some general economical and technological trends. The second part of the paper goes into some more details on a process-by-process basis.
Until recently, prototypes had to be constructed by skilled model makers from 2D engineering drawings. This is a time-consuming and expensive process. With the advent of new layer manufacturing and CAD/CAM technologies, prototypes may now be rapidly produced from 3D computer models. There are many different rapid prototyping (RP) technologies available. This paper presents an overview of the current technologies and comments on their strengths and weaknesses. Data are given for common process parameters such as layer thickness, system accuracy and speed of operation. A taxonomy is also suggested, along with a preliminary guide to process selection based on the end use of the prototype.
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