Papers by Keyword: Bearings

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Authors: Qian Zhang, Gui Tao Du
Abstract: Nature works hard to destroy bearings, but their chances of survival can be improved by following a few simple guidelines. Extreme neglect in a bearing leads to overheating and possibly seizure or, at worst, an explosion. But even a failed bearing leaves clues as to what went wrong. After a little detective work, action can be taken to avoid a repeat performance.
Authors: Jun Tu, Xiao Wei Yi, Qi Ming Wu, Rui Juan Jiang
Abstract: In recent years, the lateral creeping happened from time to time to the curved concrete girder bridges when they are in service. This attracts much attention in the fields of the design, construction, maintenance of this kind of bridges since severe damage or collapse may happen to the whole structure when the lateral creeping displacement is large enough. In this paper, a comprehensive analysis is carried out on the lateral creeping of a curved two-span continuous concrete girder bridge which has been in service for 20 years to find out the possible reasons. A finite element model is appropriately developed for this example bridge using the commercial software Midas/Civil. Taking into account the dead loads, vehicle loads, thermal loads, etc., the safety and reliability of the original design of this bridge is proved first. And then the analysis is carried out for two possible reasons, bearing failure and expansion joints failure, respectively. The results show that the real reason of the bridge lateral creeping is that the expansion joints are stuck by the concrete blocks left when the expansion joints are replaced.
Authors: Arturo González, Hussein Aie
Abstract: The translational restraints associated to pin and rocker bearings are typically idealized in the form of fixed and free conditions. However, elastomeric bearings need to be represented with springs to reasonably predict the time- and frequency-domain response of bridges under traffic-induced vibrations. Therefore, changes in the response of these bearings are common as a result of aging, deterioration, variation in loading levels and/or environmental changes. The latter makes difficult to discern if changes in the frequency content of the structural response to ambient vibration are due to changes in temperature, changes in normal operational loads or the occurrence of damage. In this paper, the bridge is idealized by a beam model supported on a hysteretic translational sprung support. The purpose is twofold: (a) to gather a better understanding of the variations of the bridge response with bearing performance; and (b) to be able to quickly identify an anomaly in the bearing. Empirical Mode Decomposition and the Hilbert-Huang Transform are employed to capture changes in the bearing stiffness from the bridge response.
Authors: P. Popper
Authors: Anton Panda, Ján Duplák, Miroslav Kormoš, Slavko Jurko
Abstract: Essential factors of each new discovery or piece of knowledge in science are predetermined, prepared and realized experiment. Every successfully realized experiment with obtained outputs and measurements indicates the gauge of asset that has been achieved by its execution. After analyzing of outputs final dependencies can be described that generalize whole experiment and allow entire process to be analytically identified. The production of bearings is very difficult process. Especially production of bearing rings is very complicated. Optimization of this process means significant savings for the company. Bearing rings are produced by turning. One of the most important parts of the turning process is cutting tool. On the base of cutting tools are determined many factors for example: quality, price, cutting speed, etc. All these factors of cutting tools are the only consequence of these cutting tools durability. Cutting tool durability determines its cutting properties and machinable ability. Specification of tool wear by means of calculation is very difficult. Durability of cutting tools is defined in standard ISO 3685. In standard ISO 3685 is defined T-vc dependence for different cutting materials and standard included process evaluation of tool durability for cutting materials made of high speed steel, sintered carbide and cutting ceramic. The article describes evaluation of T-vc dependence on the selected type of cutting materials and theirs comparison with measured values T-vc dependence that are defined in standard ISO 3685.
Authors: Anton Panda, Ján Duplák
Abstract: The problem effective and economical management of the cutting tools is often the factor that manufacturing enterprises do not attach much importance. Any manufacturer of cutting tools states in promotional and marketing materials, and also in many catalogs data about cutting tools, excluding those subject know-how. Among the following data are also recommended cutting conditions and their dependent of durability of the instrument. If the company uses different cutting parameters, knows the durability of knowledge by F.W. Taylor contained in standard ISO 3685, which can be fast deduced, because dependence on cutting speed durability is in double logarithmic in shape of linear graph. What in case that this assertion was demonstrated by Taylor in 1906 was not true? Durability of cutting tool would be different in that case, and it would not be possible to calculate or predict. With this knowledge about invalidity of the Taylor formula for new cutting tools pointed to science and practice by Professor Karol Vasilko, who in its publications published research results to indicate this fact. Article follows the research of Professor Vasilko and provides the opportunity to analytically derive the dependence of T-vc for cutting materials, where Taylor's relation does not apply.
Authors: Anton Panda, Ján Duplák, Miroslav Kormoš, Juraj Ružbarský
Abstract: Specification cutting tools durability made of cutting ceramic in machining process of steel 80MoCrV4016 is very important for economics of small and medium-sized enterprises, because cutting tool durability is factor that significantly affects the budget of these enterprises. This problematic is determined for small and medium-sized manufacturers of bearings, because steel 80MoCrV4016 is most commonly used for production of bearings. Durability of cutting tool defines lifetime of this cutting tool and it determines its suitability for select technological operation. Especially for cutting ceramic is necessary to define durability dependence on available set of cutting speeds and to determine lifetime of tools made of cutting ceramic. Technical science defines a lot of different factors, that they may be cause of shorter cutting tool lifetime. For increase cutting tool durability is necessary maximally possible elimination of these factors. Determination of cutting tool durability is very important, because provides comprehensive information how to determine appropriate technological conditions for selected cutting tool. In engineering is for determination of cutting tools durability used T-vc dependence. The article describes process how to create durability dependence for cutting tools made of cutting ceramic by means of T-vc dependence in machining process of steel 80MoCrV4016.
Authors: Leonard M. Rogers
Abstract: The paper describes a methodology for the reliable detection of incipient damage due to fatigue, fretting and false brinelling in large, heavily loaded rolling element bearings such as found in pedestal slewing cranes and ship azi-pod propulsors. It has been found that combining acoustic emission source location and spectrum analysis of the associated time-domain signatures has produced a powerful diagnostic tool for the detection of micro-damage to the various working faces of the bearing under variable speed and loading conditions, before any metal loss is evident in the bearing lubricant. Other sources of acoustic emission such as fretting at contact faces elsewhere in the body of the bearing and fluid turbulence can be resolved and quantified so as not to interfere with the diagnosis of bearing condition. Results are presented for new and damaged bearings, where the true condition has been verified when the bearings were subsequently replaced.
Authors: Maria Čilliková, Miroslav Neslušan, Kamil Kolařík, Marián Mičúch
Abstract: This paper deals with detection of surface damage after grinding of bearing rings made of case hardened steel. Micromagnetic technique based on Barkhausen noise is adopted for monitoring of surface integrity during grinding rings of large diameter (1500 mm). Except micromagnetic testing, investigation of surface integrity is also expressed in such parameters as structure alterations, residual stresses measured via X - ray technique and microhardness measurement. It was found that Barkhausen noise technique enables reliable detection of surface integrity and damage induced by dry grinding and insufficient coolant supply can be easily distinguished.
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