Improvement strategies for the formfilling in incremental gear forming processes

Incremental Sheet-Bulk Metal Forming offers an innovative and flexible approach for the manufacturing of gears. An insufficient formfilling of the generated gearing, especially of the first tooth formed, is observed. Aiming for a formfilling improvement of the first tooth element, three influencing factors were investigated. First, the prevailing friction is analyzed and a possibility for its adjustment is offered by a tailored adaption of the tool surface topographies. These were manufactured by micromilling, EDM and polishing processes and partially covered by CrAlN PVD-coatings. Based on ring-compression tests, which were performed to determine the resulting friction conditions, the analyzed topographies were transferred onto real tool surfaces and used in the incremental gear forming process. Second, the influence on the formfilling of the blank cutting process and the resulting sheet edge properties were investigated. The third aspect to enhance the formfilling of the gear elements was the modification of the process strategy of the incremental forming process. Due to different conditions for the initial and the following indentations, a preforming operation was investigated in order to realize a similar material flow for all indentations. With the combination of the best parameters regarding the tool surface, the blank cutting process and the forming strategy, an improvement of the formfilling of the first formed gear element by up to 33% and for the following gears by up to 13% was achieved.     

Interlocking intramedullary nailing of pathological fractures of the shaft of the humerus

In previous experiments using the fat substitute sucrose polyester (SPE, or olestra), no compensatory response was observed on day 2 after experimental manipulations, which reduced the percentage of energy from fat to approximately equal to 30% from 40% on day 1. In the present study a more severe manipulation was made; the amount of energy from fat was reduced from 32% to 20% to determine whether such a reduction would provoke any physiologic or behavioral response. Subjects came to the unit for two, 2-d test sessions. Intake on day 1 was fixed: subjects were given meals containing either control fat (11319 kJ, 32% of energy as fat) or SPE (9561 kJ, 20% of energy as fat). On day 2, intake was ad libitum. On day 1 subjects rated themselves as more hungry while consuming the fat-substituted meals than when consuming the control meals and they disclosed greater hunger in the end-of-day questionnaires. The effect of the manipulation was carried over into day 2. By the end of day 2, subjects had compensated for 74% of the energy (fat) deficit caused by the previous day's manipulation. These results differ from those obtained when fat was reduced from 40% to 30% of energy; this more severe reduction reveals that a reduction in fat of this size can lead to a biobehavioral response. Together, these data suggest that people could change their diet to meet dietary guidelines; however, if a more severe reduction is attempted, adherence may be made more difficult by the strength of the compensatory response.     

Low temperature isotopic exchange of molecular oxygen via the reaction of NO,NH3 and O2 over supported vanadia and molybdena catalysts

This study describes the behaviour of NO, NH₃ and¹⁸O₂ over supported molybdena and vanadia catalysts. The study was carried out using differential scanning calorimetry. The catalysts show different behaviour with respect to the reaction of NO, NH₃ and O₂ and similar behaviour with respect to the formation of water.     

A simple method of restoring lidfunction in facial nerve paralysis with permanent magnets (author''s transl)

Anxiety arising from masturbatory guilt plays a major role in the production of frigidity and impotence. Reduction of this anxiety through greater community awareness of the normality of masturbation is therefore a fertile area for the principles of preventive medicine to be applied.     

Enhanced optical polarization anisotropy in quantum wells under anisotropic tensile strain

Anisotropic in-plane strain in quantum wells leads to an optical polarization anisotropy that can be exploited in optoelectronic devices such as modulators. A theoretical model shows that the behavior of the polarization anisotropy with increasing strain anisotropy is radically different for quantum wells under anisotropic tensile and compressive strains of equal magnitude. This strikingly different behavior arises from the different valence-subband mixing that occurs in the cases of anisotropic tensile and compressive strain. Specifically, the mixing of the first heavy- and light-hole subbands that occurs only under anisotropic tensile strain is central to the polarization anisotropy.     

Lewis-Säure katalysierte Additionen an ungesättigte Fettstoffe I: SnCl4-katalysierte Addition von Nitrilen an Ölsäuremethylester und 10-Undecensäureethylester

Lewis Acid Catalyzed Additions to Unsaturated Fatty Acids I: SnCl₄-Catalyzed Additions of Nitriles to Methyl Oleate and Ethyl 10-Undecenoate Nitriles have been added to esters of unsaturated fatty acids by SnCl₄-catalyzed Ritter-reaction to give esters of N-acylamino fatty acids in good yield with moderate, temperature dependent isomerization.     

Aufstellung einer kinematischen Stoßtheorie und deren Anwendung auf den körperlichen Energiestrom durch ein Gitter

Zusammenfassung Auf Grund einer Erg?nzung des skalaren Restitutionskoeffizienten von I. Newton zu einem Tensor wird eine kinematische Theorie des Sto?es vorgeschlagen und im besonderen für die bindungsfreie Tr?gheits-bewegung starrer Umdrehungsk?rper durch ein Gitter (d. h. eine eben angeordnetes Reihe paralleler, starrer Dr?hte) formuliert. Vier Hauptrestitutionen transversaler Isotropie geben die Grenzf?lle elastischen oder unelastischen und glatten oder haftenden Sto?es wieder. Für diese F?lle wurden Winkelverteilungen der Sto?k?rpergeschwindigkeit nach einem Sto? sowie das energetische Auffang-und Drehverm?gen eines Gitters nebst einigen wichtigen Hilfsfunktionen in Abh?ngigkeit vom Einfallswinkel oder vom Verh?ltnis von Sto?k?rperdurchmesser zu Drahtabstand für verschiedene Parameter berechnet und graphisch aufgetragen. Mitteilung aus der Bundesanstalt für Materialprüifung (ABM), Berlin-Dahlem. Dank gebührt der von HerrnWolfgang Strogies geleiteten Rechenstelle der BAM und Herrn Dr. phil.Altred Thomescheit für die Mitarbeit bei numerischen Berrechnungen soview dem Wirtschaftssenator von West-Berlin für finanzielle Beihilfe.