Summary

The aim of the present work is to determine the influence of technologically produced boron surface layers on the friction parameters in the sliding pairs under the conditions of mixed friction. The tribological evaluation included ion nitrided, pack borided, laser borided, quenched and tempered surface layers and TiB2 coating deposited on 38CrAlMo5-10, 46Cr2 and 30MnB4 steels. Modified surface layers of annular samples were matched under test conditions with counter-sample made from AlSn20 bearing alloy. Tested sliding pairs were lubricated with 15W/40 Lotos mineral engine oil. The tribological tests were conducted on a T-05 block-on-ring tester. The applied steel surface layer modification with boron allow creating surface layers with pre-determined tribological characteristics required for the elements of kinematic pairs operating in the conditions of sliding friction. Pack boronizing reduces the friction coefficient during the start-up of the frictional pair and the maximum start-up resistance level is similar to the levels of pairs with nitrided surface layers.
① Instytut Techniki, Uniwersytet Rzeszowski, 8721186, e-mail: ul Rejtana 16A, 35-959 Rzeszów, tel.: 017
spmom-09v44n1_p-007.pdf (214.95 Kb)

Summary

This work is the continuation of the research concerning the dynamic model of a rotating unit in a turbocharger. In this model, masses of rotors and a shaft have been modelled as combined masses. The rotating unit has been propped on two supports forming lateral sliding bearings with a floating ring bearing. Each bearing is designed including the floating ring bearing mass. The shaft of a rotating unit rotates at angular velocity ω1; whereas, a floating ring bearing rotates at angular speed ω2.
A mathematical model constitutes a system of differential equations, mutually coupled. The mathematical model has been solved by determining the following: acceleration, velocity, and displacement in each knot. The paper shows the crucial influence of a bearing relative clearance on static and dynamic properties of a rotating unit in a turbocharger. The author suggests that the rotating unit will work in a stable state only in those cases where for given parameters the geometry of oil films is appropriately chosen. In conclusion, the author formulates suggestion that might be useful for the designers who work with these types of bearings.
① Rzeszów Uniwersity of Technology, Faculty of Mechanical Engineering and Aeronautics, Powstańców Warszawy Ave. 8, 35-959 Rzeszów, tel.: (17) 865-16-40, e-mail:
spmom-09v44n1_p-019.pdf (5.46 Mb)

Summary

Understanding of reliability measures for different technical facilities plays an important role in a decision-making process. Most methods used for the estimation of reliability measures impose an additional error on the final result. The error, called the method’s error, is not related in any way to data accuracy and reliability. It is the method’s error. Both assumptions and application conditions formulated for the analysed methods, though not very accurate, seem to be sufficient for theoretical validation of the method. So far, due to a lack of appropriate ways of determination of errors in reliability estimation methods, such errors are not considered in practical applications and the accuracy of the final results is not analysed. Rough estimates without proper error evaluation may become useless. The paper analyses the accuracy of the most popular methods used for the determination of reliability measures for technical facilities. The relationships presented in the paper help to determine the errors of the presented methods. The relationships may be used for different major technical facilities.
① Institute of Water Supply and Environmental Protection, Cracow University of Technology, 31-155 Kraków, Warszawska 24, .
spmom-09v44n1_p-029.pdf (149.43 Kb)

Summary

An operational potential is the measure of a usability of a technical object. The operating and service processes carried out during an exploitation phase change the quantity of the operational potential enclosed in the object. The operating processes decrease and the service processes increase this potential. Therefore, during the exploitation phase, the usability of the machine changes. Describing a process of changes in the operational potential as a time function, it is possible to determine a moment of time at which the operation process should be stopped and the service process should be started to avoid disability of the object. This issue is especially important in the case of a complex, crucial, technical object, because, for such an object, the moment to start the service process has to be determined several months in advance. In the paper, a function of the amount of the operational potential enclosed in the object is described. Next, the course of the function during the operating and service processes is defined. On the basis of the described function, the idea of the service activity start time determination is also presented.
① Radom University of Technology, Faculty of Mechanical Engineering, Department of Thermal Technology, 26-600 Radom, ul. Krasickiego 54, Poland, tel. (48) 48 361 71 49, e-mail:
spmom-09v44n1_p-037.pdf (158.52 Kb)

Summary

This paper presents the method for the creation of an export knowledge base. Such a base can be widely use for supporting the process of complex technical object servicing. The first step for is servicing analysis of the object. During this analysis, it is necessary to perform the grouping and classification of the functional elements of the object. It is realised using the functional scheme of the object, which is also presented. Further, diagnostic information is combined with specialised knowledge of experts and becomes transformed into the set of servicing information. The participation of experts in the process of the preparation of an expert knowledge base is significant. The purpose here is to capture information that will be the basis for the design of a servicing system dedicated to the particular technical object. The methods proposed were verified with an appropriate example, where the set of specialised diagnostic information of the object was determined.
① Koszalin University of Technology, Department of Mechanical Engineering, Racławicka 15/17, 75-620 Koszalin, Poland, e-mail:
spmom-09v44n1_p-049.pdf (189.61 Kb)

Summary

The main goal of machine diagnostics is their state determination, prognosis, and discovering its origin. All the three above-mentioned phases are necessary for proper operation of this important group of technological machines. In order to carry out these tasks, new methods have been constantly searched for. In this paper, there is presented a new approach to machine-tools state prognosis, based on their accuracy tests. Base on the cycle of standard diagnostic tests, the history of diagnostic symptoms, necessary for the phase of the state prognosis, is being created. The same, constant testing conditions enable observation and comparison of the machine state changes in time and, on this basis, prognosis of its further operation. Algorithm activities that make it possible to work out the state prognosis have also been shown. The procedure proposed in this paper extends the set of diagnostic tools (in the field of prognosis) for the numerous and undoubtedly important group of technological machines which make up machine tools.
① Uniwersity of technology and Life Sciences in Bydgoszcz, faculty of Mechanical Engineering, Prof. S.Kaliskiego Ave. 7, 85-789 Bydgoszcz, tel. (052) 340-86-23, e-mail:
spmom-09v44n1_p-063.pdf (1.34 Mb)

Summary

The review of the sparse case studies of ecobalancing analyses of the complex technical objects (machines and devices) clearly indicates the operation phase of their life cycle as causing the most harmful impacts on the environment. In the paper the example of environmental analysis of the operation period and related disposal processes of representatives of food industry machines is presented. The research ecobalancing method, one of the most commonly worldwide used and objects selected for the analysis are also described. The selected results of analysis are presented, including the total environmental indices, the environmental profiles of the regarded machines, the study of the kinetics and the main factors determining the environmental impacts of machines during the operation period.
① Poznań University of Technology, Faculty of Working Machines and Transportation, Institute of Working Machines and Motor Vehicles, Piotrowo 3 St., 60-965 Poznań, Poland.
spmom-09v44n1_p-075.pdf (387.53 Kb)

Summary

The study shown in the paper concerns the last stage of the products’ life cycle, withdrawing from exploitation. The research is concentrated on passenger vehicles. Different aspects of car recycling in Poland were contemplated. The general description of this initial study on car recycling scenarios and their environmental consequences is presented. Scenarios are characterised in detail to define changes in the number of vehicles recycled in Poland in the future. The LCA (Life Cycle Assessment) method and Ecoindicator 99 procedure are used to evaluate environmental aspects of the recycling processes. The main environmental impacts are classified in three general categories: human health, ecosystem quality, and resources. Obtained results illustrate the scale of environmental impacts coming from car recycling.
① Poznań University of Technology, Faculty of Working Machines and Transportation, Institute of Working Machines and Motor Vehicles, Piotrowo 3 St., 60-965 Poznań, Poland, tel.: (61) 665-21-10, e-mail:
spmom-09v44n1_p-077.pdf (456.98 Kb)