Wälzlager in der Vakuumtechnik

Rolling Bearings For The Use In Vacuum The use of rolling bearings in vacuum is limited due to technical reasons regarding the standard lubricants. Nevertheless there are options to use those machine elements anyways. Therefore an alternative lubrication, e.g. Molybdenum Disulfide, will be applied successfully. as a result rolling bearings can be used in surroundings with high temperatures as well as in vacuum. The following describes how the assume the lifetime of rolling bearings and shows how to optimize the systems with respect to its lifetime and therewith to the costs of the element by using it within such extreme surroundings. The shown options then will be proved by experimental tests.     

Modeling planar slider-crank mechanisms with clearance joints in RecurDyn

Revolute joints in applications always show clearance between pin and bushing due to manufacturing tolerances, the need of relative motion or progressing wear. Many researchers developed and investigated methodologies to calculate the dynamic behavior of mechanisms with such imperfect joints. Very often they use a simple slider-crank mechanism to test or demonstrate the capability of their approaches. In this paper, a methodology for simulating a slider-crank mechanism with an imperfect revolute joint in RecurDyn, a commercial multibody simulation tool, is presented. Therefore, a thorough investigation of existing contact, damping and friction force models as well as different ways of modeling revolute joints in RecurDyn was conducted. For the investigation of the damping models, a special program for calculating the model parameters for a given coefficient of restitution was developed. Only one damping model was capable of reproducing the experimental results, which were found in literature. Some characteristic results of the slider-crank mechanism are presented in a way that they can be compared to results in other papers. Thereby. a good correlation was achieved, demonstrating the capabilities of the methodology.     

Experimentelle und simulative Untersuchungen zum Einfluss der Lageabweichungen im Nocken-Rollen-Kontakt auf die Ventiltriebskräfte

As part of a cooperation project, Daimler AG and the Institute of Machine Elements, Gears, and Transmissions (MEGT) at the Technische Universität Kaiserslautern are carrying out detailed investigations on a valve train with roller lever. The aim of the project is to develop a detailed simulation method that allows the secondary movement of the valve train to be modeled and thus represents an extension of the classic valve train dynamics simulation. This opens up the opportunity to evaluate the processes within the valve train in detail in the early stages of the product development process. This report introduces the validation of the methodology based on experimental results. First, the focus is placed on the cam-roller contact, which induces the secondary movement of the valve train. This movement takes place in the axial direction of the camshaft so that the validation takes place on the basis of the measured force in this direction. The force is dependent on the load, i.?e. the combination of speed and normal force, as well as the angular misalignments between cam and roller. Following the validation of the detailed modeling of the cam-roller contact, the gained knowledge is transferred into the extended valve train simulations. Finally the valve train simulation is validated.     

How operators make use of wide-choice adaptable automation: observations from a series of experimental studies

The present paper is concerned with the design of adaptable automation. It analyses the aggregated data from five experiments (N = 154) to examine which automation levels operators prefer, how often they switch between them, and whether performance is associated with frequent switching or the automation levels being used. Using wide-choice adaptable automation (i.e. up to six levels were offered), the experiments were conducted using a PC-based simulation of a complex work environment. The results showed that about 95% of operators had a clearly preferred automation level, which they used for more than 50% of the time. They strongly preferred intermediate automation levels over levels at the higher and lower ends of the scale. Most operators switched rarely between levels and when they did, they usually made small adjustment rather than large changes. Several implications for the design of adaptable automation were derived from the empirical data.     

A Multiplexed Four Channel On-Line Iodine Monitor

Abstract

A robust autonomous system is described for the spectrophotometric determination of aqueous elemental iodine in multiple flowing process streams. The quantitative methodology uses characteristic absorbance at 460 nm, corrected for baseline drift using absorbance at 600 nm. Linear dynamic ranges of 0.2 - 25 mg/L, 0.4 - 45 mg/L, and 2 - 250 mg/L have been attained using path lengths of 1 cm, 5 cm, and 10 cm respectively. The multiplexed iodine monitor has proven capable of continuous operation for periods of up to eighteen months.     

Partikelform und Porosität von biogenen Pyrolysekoksen

Char particles from pyrolyzed biomass vary in particle size and shape. On average, the particles are more elongated the larger their size. The average size‐specific elongation is almost alike for all investigated samples, i.e. independent from their source material and process. The particle collectives cannot be characterized accurately with classical particle size distributions, which assume spherical particle shape. Accounting for their shape, they can be described more accurately with particle size distributions that are based on an ellipsoid model. The high bulk porosity is mainly attributed to the spaces between particles.     

MODELLING OF MICROSTRUCTURE EVOLUTION AND PROPERTIES OF LOW-CARBON STEELS

1.IntroductionMicrostructureprocessmodelsareincreasinglyonhotstriprollingofste.l[1--7].Thesemodelsfrequentlyincorporateagreatdealofempiricismwithcomparativelytightprocessrangesofapplicability.Morefundamentallybasedprocessmodelsarerequiredtodeveloppredictivetoolstooptimizetheproductionforawiderangeofmilldesignsandprocessingconditions.Theprocessofhotstriprollingoflow--carbonsteelscanbesubdividedintothreeprin-cipalstages:(i)reheating,(n)rollingand(iii)cooling(watercoolingontherun--outtableandsubs…     

The busbar system for Wendelstein 7-X prepared for assembly and operational loads

Forschungszentrum Jülich has taken over the design, manufacturing and assembly of the superconducting busbar system for the stellarator Wendelstein 7-X. This includes the busbars itself, the support structure consisting of supports and clamps, and the joints for electrical and hydraulic connection of the busbars and coil terminals. Apart from providing the required electrical connection scheme, the busbar system has to be designed for relevant electrical and mechanical loads. Numerous interfaces and geometric boundary conditions define the confined space to accommodate the busbars and their support elements. This article describes how the individual challenges to engineering have been met in the course of the project. This includes design concepts and the method for iterative design of supports with respect to the individual load distribution caused by the supports itself.