MOST CITED
Update: 2021-07-01
Task „Implementation of procedures ensuring the originality of scientific papers published in the quarterly „Eksploatacja i Niezawodność – Maintenance and Reliability” financed under contract 532/P-DUN/2018 from the funds of the Minister of Science and Higher Education for science dissemination activities.
wear
Analysis of the influence of lubrication conditions on tool wear used in hot die forging processes
The study discusses the subject of lubrication in the processes of hot die forging with the consideration of the durability of forging tools and instrumentation. It presents a literature research as well as the authors’ own investigations of the effect of the use of cooling and lubrication agents, the amount of the dosage as well as the direction of its application, and also the factors influencing the tribological conditions. The lubrication devices and systems currently applied in the industry have been analyzed as well. On this basis, making use of their knowledge and experience, the authors have developed and constructed a lubricating device. The elaborated system, implemented into the industrial process, makes it possible to select and ensure the optimal tribological conditions of the process by way of controlling the amount and frequency of the applied lubricant dosage. It can constitute an alternative for the manual method of lubricant application, which is dependent on the human factor, or the fully automated, yet expensive, lubrication systems. The obtained test results point to potential possibilities of a permanent introduction of the constructed device also into other forging processes, through its integration with a manipulator. The proposed solution ensures more stability and higher repeatability of the lubrication conditions as well as increases the efficiency of the production process, thus significantly reducing the unit costs of the production of forgings.
Time-dependent reliability of spur gear system based on gradually wear process
To study dynamic evolution law of mechanical reliability caused by wear, gear transmission system is taken as a research object. Considering the effect of clearance caused by wear on gear teeth load in double meshing area, the formula of dynamic distribution load which is undertaken by two adjacent teeth is deduced. And the distributed pressure and meshing speed, which should be taken into account while calculating gear wear, are obtained based on the Winkler surface model and principle of tooth mesh. Based on the Archard’s wear model, numerical simulation model for wear in spur gear is deduced, and the wear depth of each meshing points on teeth outline with different wear cycles are obtained. The calculation wear model is replaced with a surrogate model with Neural Network and Kriging method to overcome time-consuming defect. Random process model is integrated with the surrogate model, and dynamic reliability for nonlinear stochastic structure with unknown distribution characteristic is obtained with Neural Network-based Edgeworth series technique and four moment methods, which is compared with Kriging-based Monte Carlo simulation method. The computational efficiency and accuracy are also demonstrated.
Outline of a method for estimating the durability of components or device assemblies while maintaining the required reliability level
The paper includes a probabilistic method for evaluating the durability of components and device assemblies which operate under the impact of destructive processes. As a result of these processes, wear that causes deterioration of their cooperation conditions occurs. It is assumed that a component operates reliably when the wear does not exceed the acceptable (limit) values. In mathematical terms, this method is based on a differential equation, after the transformation of which, it is possible to obtain the Fokker-Planck type partial differential equation. The specific solution of this equation allows for obtaining the density function of the probability wear in the normal distribution form. The paper presents two methods for determining the durability. The first one involves the application of the wear density function, and the second one consists in determining the probability density function of the time of reaching the acceptable state, and its use in order to determine the component or assembly durability. The paper presents a numerical example on the aircraft technology operation process.
Badania odporności na zużycie wybranych materiałów poddanych procesowi nagniatania ślizgowego
W artykule przedstawiono wyniki badań wpływu procesu nagniatania ślizgowego realizowanego z wykorzystaniem różnych ceramik na wielkość zużycia oraz siłę tarcia elementów stalowych. Dodatkowo badaniom poddano powierzchnie po procesach szlifowania, docierania oraz polerowania. Skojarzenie materiałowe stanowiły tarcze stalowe ulepszone cieplnie do twardości 40±2 HRC oraz kulki ze stali100Cr6 o twardości 62 HRC. Badania zrealizowano przy trzech prędkościach poślizgu: 0,16 m/s, 0,32 m/s oraz 0,48 m/s. Badania udowodniły możliwość poprawy wybranych właściwości tribologicznych par trących dzięki zastosowaniu procesu nagniatania ślizgowego a także pozwoliły na ustalenie szeregu zależności pomiędzy parametrami charakteryzującymi strukturę geometryczną powierzchni oraz parametrami tribologicznymi.
Investigation of wear resistance of selected materials after slide burnishing process
The article presents the research on the impact of slide burnishing process carried out with use of various ceramics on friction and wear of steel elements. In addition, surfaces after grinding, lapping and polishing processes were tested. The tribological couple was made of steel discs, toughened to a hardness of 40 ± 2 HRC, and balls made of 100Cr6 steel with a hardness of 62 HRC. The tests were carried out at three sliding speeds: 0.16 m/s, 0.32 m / s and 0.48 m/s. The research proved the possibility of improving selected tribological properties of friction pairs thanks to the use of slide burnishing process and also allowed to establish a number of relationships between the parameters characterizing the surface topography and the tribological parameters.
Identification of factors that differentiate motor vehicles that have experienced wear or failure of brake system components during the warranty service period
The paper focuses on issues related to selected automotive brakes with the aim of applying the proposed methodology to other structural systems of this type. The main aim of the paper is to identify the factors that differentiate the course of wear and occurrence of a fault in brake system components of passenger cars and light commercial vehicles during the warranty service period. The following methods were used in this study: systematic literature review, process analysis, and descriptive and inferential statistics, including analysis of variance and multiple classification analysis. As a result of an analysis of 295 brake system repairs, six differentiating factors that allowed for ex post analysis of the repairs were identified. An analysis of the interaction of these factors made it possible to distinguish three groups of motor vehicles depending on the cause of failure of the braking system. Based on the data generated in the warranty process, it is possible to determine the factors that differentiate the occurrence of a fault and the course of brake disc and pad wear.
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