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Comparison of the tests chosen for material parameter identification to predict single point incremental forming forces
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Forming of High-strength Steels Using a Hot-melt Dry Lubricant
No full textThe increasing use of high strength steels in a variety of mechanical engineering applications has illuminated problems associated with galling in sheet metal forming operations. Galling is a tribological phenomenon associated with transfer of material from the steel sheet to the tool surface during forming resulting in seizure of the tool/steel sheet contact and extensive scratching of the steel sheet surface. As a result, a number of concepts have been developed in order to reduce the tendency to galling in metal forming, including the development of new dry lubricants, new forming tool steel grades and improved surface engineering treatments such as the deposition of low friction CVD and PVD coatings. In the present study the performance of a hot-melt dry lubricant in the forming of hot and cold rolled and hot-dip galvanized high strength steel has been evaluated and compared with a conventional rust protection oil using four different tests methods, i.e. a strip reduction test, a bending under tension test, a stretch-forming test and a pin-on disc test. In the tests, two different cold work tool steels, a conventional steel grade and a nitrogen alloyed PM steel grade were evaluated. The results show that the different tests used give consistent results and valuable information concerning the galling tendency of the steel sheet, tool steel and lubricant combinations investigated and when combined can be used to rank the galling resistance of lubricants and tool steels. The results clearly show that the dry lubricant provides better lubrication and generates less galling than the rust protection oil. Also, the nitrogen alloyed PM steel grade shows a significantly higher galling resistance as compared with the conventional steel grade and can, in combination with a dry lubricant, preferably be used in sheet metal forming operations to further improve the galling resistance
Metal Additive Manufacturing - State of the Art 2020
No full textAdditive Manufacturing (AM), more popularly known as 3D printing, is transforming the industry. AM of metal components with virtually no geometric limitations has enabled new product design options and opportunities, increased product performance, shorter cycle time in part production, total cost reduction, shortened lead time, improved material efficiency, more sustainable products and processes, full circularity in the economy, and new revenue streams. This Special Issue of Metals gives an up-to-date account of the state of the art in AM
Tool and Die Making, Surface Treatment, and Repair by Laser-based Additive Processes
No full textThis paper explores the possibilities to use laser-based additive processes to make, surface treat and repair/remanufacture tools, dies and molds for cold working, hot working, and injection molding. The failures encountered in these applications are described. The materials used conventionally and in the laser additive processes are accounted for. The properties of the tools, dies and molds made by Laser-based Powder Bed Fusion (L-PBF) are as good as and in some cases better than the properties of those made in wrought materials. Shorter cycle time, reduced friction, smaller abrasive wear, and longer life cycle are some of the benefits of L‑PBF and Directed Energy Deposition with powder (DED-p) (or Laser Metal Deposition with powder, LMD‑p, or Laser Cladding, LC). L‑PBF leads to higher toolmaking costs and shorter toolmaking lead time. Based on a review of conducted investigations, this paper shows that it is possible to design and make tools, dies and molds for and by L‑PBF, surface functionalize them by DED-p (LMD‑p, LC), and repair/remanufacture them by DED-p (LMD‑p, LC). With efficient operational performance as the target for the whole tool life cycle, this combination of L‑PBF and DED-p (LMD‑p, LC) has the greatest potential for hot working and injection molding tools and the smallest for cold working tools (due to the current high L‑PBF and DED-p (LMD‑p, LC) costs).Dieser Beitrag untersucht die Möglichkeiten, laserbasierte additive Verfahren zur Herstellung, Oberflächenbehandlung und Reparatur/Nachbearbeitung von Werkzeugen, Gesenken und Formen für die Kalt- und Warmumformung sowie den Spritzguss einzusetzen. Die bei diesen Anwendungen aufgetretenen Fertigungsfehler werden beschrieben. Die konventionell und in den laseradditiven Verfahren verwendeten Werkstoffe werden berücksichtigt. Die Eigenschaften der durch Laser-based Powder Bed Fusion (L-PBF) hergestellten Werkzeuge, Matrizen und Formen sind genauso gut und in einigen Fällen besser als die Eigenschaften der konventionell hergestellten Bauteile. Kürzere Zykluszeiten, geringere Reibung, geringerer Abrieb und längere Lebensdauer sind einige der Vorteile von L‑PBF und Directed Energy Deposition mit Pulver (DED-p) (oder Laser Metal Deposition mit Pulver, LMD‑p, oder Laser Cladding, LC). L‑PBF führt zu höheren Werkzeugbaukosten und einer kürzeren Werkzeugbau-Durchlaufzeit. Basierend auf einem Überblick über durchgeführte Untersuchungen zeigt dieser Beitrag, dass es möglich ist, Werkzeuge, Matrizen und Formen für und durch L‑PBF zu konstruieren und herzustellen, sie durch DED-p (LMD‑p, LC) oberflächenfunktionalisieren zu können und sie durch DED-p (LMD‑p, LC) zu reparieren/nachzubearbeiten. Mit effizienter Betriebsleistung als Ziel für den gesamten Werkzeuglebenszyklus hat diese Kombination aus L‑PBF und DED-p (LMD‑p, LC) das größte Potenzial für Warmarbeits- und Spritzgießwerkzeuge und das geringste für Kaltarbeitswerkzeuge (aufgrund der derzeit hohen L‑PBF- und DED-p (LMD‑p, LC)-Kosten).Funding agency:Örebro University</p
Compensation of deep drawing tools for springback and tool-deformation
Get PDFManual tool reworking is one of the most time-consuming stages in the preparation of a deep drawing process. Finite Elements (FE) analyses are now widely applied to test the feasibility of the forming process, and with the increasing accuracy of the results, even the springback of a blank can be predicted. In this paper, the results of an FE analysis are used to carry out tool compensation for both springback and tool/press deformations. Especially when high-strength steels are used, or when large body panels are produced, tool compensation in the digital domain helps to reduce work and save time in the press workshop. A successful compensation depends on accurate and efficient FE-prediction, as well as a flexible and process-oriented compensation algorithm. This paper is divided in two sections. The first section deals with efficient modeling of tool/press deformations, but does not discuss compensation. The second section is focused on springback, but here the focus is on the compensation algorithm instead of the springback phenomenon itself
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Metal Additive Manufacturing—State of the Art 2020
No full textAdditive manufacturing (AM), more popularly known as 3D printing, comprises a group of technologies used to produce objects through the addition (rather than the removal) of material [...
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