ALBERT

Notes: Me3SiCl bildet mit N-Methylimidazol (NMI) eine bei Raumtemperatur beständige, kristalline 1:1 Verbindung. Nach der Röntgenstrukturanalyse entsteht unter Spaltung der Si—Cl-Bindung und Anlagerung eines NMI-Rings eine Verbindung ionischer Struktur [Me3Si(NMI)]+Cl- 1. Die Reaktion von Me2HSiCl mit NMI (Molverhältnis 1:2) führt unter Spaltung der Si—Cl-Bindung und Koordination von zwei NMI-Ringen zur Verbindung [Me2HSi(NMI)2]+Cl- 2. Bei der analogen Umsetzung von Me2SiCl2 mit NMI (Molverhältnis 2:1) entsteht eine Verbindung, die Me2SiCl2 und NMI im Molverhältnis 1:2 enthält. Bei der Sublimation werden Einkristalle der Verbindung [Me2Si(NMI)3]2+ 2 Cl-· NMI 3 erhalten.

Notes: One of the basic prerequisites for rational and high quality production of plastic parts is a tool layout tailored to the production process. To date, both design and construction have generally been based on values acquired by experience. This first, necessitates highly qualified personnel and second, involves what is frequently time consuming and costly finishing work. Experience acquired so far with computer-aided layout of injection molds shows that even a designer with little experience reaches the target more quickly and more reliably. At the same time he is able to draw on the results of intricate calculation and simulation methods which he was unable to apply in the past for reasons of time alone. This paper thus sets out the possibilities currently open and the experience available for computer-aided mold layout. The chief point of focus here is a system for the layout of injection molds. Working on from this system, however, the potentials for computer application are presented for blow mold- and foaming mold-design. After finding the mold principle, mold layout essentially divides up into two major areas, namely dimensioning calculations (CAE) and compilation of production documents (CAD). In dimensioning, the different functional elements of the mold are calculated. The aids that have been developed and the potentials of computer-aided dimensioning are presented with examples from the fields of rheological, thermal, and mechanical mold layout. Computer-aided rheological layout divides up into two steps. The first gives information on qualitative filling behavior (filling picture, flow paths) and the second provides quantitative results (pressures, shear stresses, temperatures). Computer-aided thermal layout similarly divides up into part steps. These are a rough overall energy balance, a rough layout of the tempering system, a segmented layout, and a homogeneity check, which involves simulating the temperature conditions in the mold by means of difference methods. When it comes to mechanical layout of the mold, programs are available for deformation calculations on basic cases and these will frequently be sufficient. For more complex cases of loading and deformation, a finite element program is used. Graphic data processing units can be used to supply extra facilities - first, to provide an aid for the simulation programs in dimensioning and second, to rationalize the compilation of the production documents. An illustration of a CAD workplace is given, incorporating the necessary computer configuration and peripherals. Compiling production documents is essentially a problem of variant design. The variants in this case are the individual components of the mold and a number of standardized accessories that can be called up as “standardized components.” The mold cavity, however, always has to be a free design. All programs are dialogue driven and are in a standardized manner so that even designers with no data processing experience can use the computer as an aid. The CAD/CAE system presented duly fulfils all these requirements. It allows the designer, at a single computer work station, to carry out both simulation and dimensioning calculations, to obtain information on material data, and to compile production documents on the basis of variant and free design. This provides the designer with a readily manageable aid and makes a considerable contribution towards improving the design result. Finally, the capacity of different computer concepts and the CAE/CAD/CAM systems on the market are discussed. For the future it will be possible to establish a computer-aided link between the different areas of design, from development of the molded part, via mold design and production, through setting the processing parameters of the injection molding machine.

Notes: Nach dem Pulverpackverfahren werden Diffusionsschutzschichten auf den Stahl 13 CrMo 44 (Werkstoff Nr. 1.7335) aufgebracht. Ihr Aufbau wird durch Aluminiumkonzentration in der Probenoberfläche, Schichtdicke und Oberflächenbeschaffenheit beschrieben. Es wird berichtet, wie diese Kenngrößen von Pulverzusammensetzung, Beschichtungstemperatur und Beschichtungszeit abhängen. In 16wöchigen Auslagerungen pulveraluminierter Proben bei 608 °C unter Schutzgas erfolgt nur eine geringe Abnahme der Aluminiumkonzentration in der Probenoberfläche und keine Schichtverbreiterung. Im Verlauf der Auslagerung bildet sich zunehmend eine neue Phase der Zusammensetzung Fe3Al in der Interdiffusionszone aus.

Notes: Coated pack aluminized low alloyed steels are known for their good resistance against high temperature corrosion up to 700 °C, where diffusion stability is still sufficient. In typical high temperature applications, coating and substrate are subjected to thermal fatigue. In this study the metallurgical stability of a coated, pack aluminized, low alloyed steel is reported. The specimens were cyclically quenched from 700 °C to room temperature or liquid nitrogen temperature respectively, to assess the importance of thermal shock severity on the kinetic of degradation. In particular, crack initiation and growth were studied. The dependence of microcrack densities upon numbers of cycles, cooling rates and specimen geometry is reported.

Notes: Using idealised assumptions, the stress condition in the semi infinite body of the Hertzian contact region can be calculated for various geometries as a function of the surface pressure (normal force), the friction (tangential force at the surface) and the residual stresses in the material.Equivalent stresses can be formed from the coordinate stresses using various stress hypotheses (distortion energy hypothesis, shear stress hypothesis and alternating shear stress hypothesis).The effects of friction, residual stresses and contact geometry on the location and magnitude of the equivalent stresses appearing in the material have been investigated, the stress hypotheses being evaluated in terms of the extent to which they take account of these effects in an appropriate form.These investigations show clearly that the distortion energy hypothesis is the best representation of the extent of material stress in the case of dynamically loaded rolling elements. The shear stress hypothesis can be considered as a good approximation whereas the alternating shear stress hypothesis is only capable of providing useful conclusions to a limited extent.

Notes: Unter Schwingungsverschließbeanspruchung wird hier eine oszillierende Gleitbewegung von sehr kleiner Amplitude (1-3 μm) bei gleichzeitiger schwingender Werkstoffbelastung verstanden. Kennzeichnend ist das Auftreten von Scheuer- und Reibschweißstellen. Diese Oberflächenschäden bewirken die Bildung von Mikrorissen, welche sich ausbreiten und zum vorzeitigen Ermüdungsbruch des Bauteils führen. Zur Simulation solcher Schadensvorgänge, wie sie bei Paarverbindungen wie Wälzlagersitzen, Turbinenschaufeln und Wellen Naben-Verbindungen bekannt sind, wird eine Reibkufenapparatur benutzt.Das Plasmanitrieren und das Plasmanitrocarburiern metallischer Werkstoffe sind thermochemische Wärmebehandlungsverfahren, die den mikrostrukturellen Aufbau der oberflächennahen Bereiche Verändern. Dadurch werden die mechanisch-technologischen Eigenschaften von Werkstücken, wie z. B. der Verschleiß- und Korrosionswiderstand sowie die Dauerfestigkeit verbessert. Aufgrund seiner verfahrenstechnischen Vorteile wird das Plasmanitrieren inzwischen in vielen Fertigungsbereichen angewendet.Die Ermittlung der Schwingungsverschleißfestigkeit an vergütetem und plasmanitriertem bzw. -nitrocarburiertem 34 CrAlMo 5 zeigt, daß durch diese Behandlungsverfahren die Zugschwellfestigkeit um bis zu 14%, die Schwingungsverschleißfestigkeit um bis zu 50% angehoben werden kann.