Wyniki wyszukiwania - Biblioteka Nauki

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Improvement of the internal combustion engine cam-tappet pair characteristics using numerical step-by-step cam design method

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Vasilyev A. , Bakhracheva J.

Journal of KONES

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2009

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tom Vol. 16, No. 1

517-522

EN

In this paper the numerical step-by-step method of cam profile design is presented. The results of its using for internal combustion engine valve gear are submitted. Its basis is a principle of step-by-step formation of the tappet movement law taking into account restrictions, which permit to refuse of before hand, accepted cam profile description. Thus instead of the analytical law of tappet movement the numerical representation is used, and the algorithm of positive and negative acceleration forming provides maximum cam efficiency, depending on the tappet displacement diagram completeness and connected to it valve timing. A longside with formation of the tappet movement law definition of the necessary data for manufacturing and the control of the corresponding cam profile using various kinematic schemes is stipulated. This method allows to profile of maximum efficiency cams in view of many restrictions on parameters, connected to valve gear serviceability and reliability: contact stress in cam-tappet pair, pressure angle, coverage factor of the valve springs effort, radius of cam profile curvature, oil film thickness in the cam-tappet pair and the restrictions on the higher order of derivative from the tappet displacement on the cam turn angle. Efficiency ofa considered method has been confirmed at profiling cams for lines of tractor and automobile engines.

2

The method for reliability estimation of the machine elements under low temperature conditions

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Vasilyev A. , Bakhracheva J.

Journal of KONES

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2009

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tom Vol. 16, No. 1

513-517

EN

The subject considered are the theoretical dependences between parameters in a small scale yielding zone length, and a plastic zone at cave-in spherical indentor. The loadings of a spherical (D=5 mm) indenter in the range from 147 to 11875 N within absolute temperature range 77-293 K were applied. According to this model, fracture conditions occur when the stress sigma z in the centre of ball impression exceeds critical stress of brittle fracture of. Then the indentation energy, corresponding to condition HM =sigma f, where HM and sigma f are the Meyer 's hardness and the material 's critical cleavage fracture stress, was calculated. The comparison of fracture toughness K Ic, and specific energy of plastic deformation on depth of a plastic zone at introduction spherical indentor up values reveals linear relation-ships KIc(up) for all steels in all the investigated temperature range. For the purposes of non-destructive Sk estimation, the relation-ship between S k and misses stress sigma i, in the centre of impression at the temperature 77 K was established. At last fracture toughness values can be calculated from the single unified equation for all investigated steels. The model proposed can be used for predicting the cracking resistance of the machine elements in a low temperature range.

3

Experimental investigation and modelling of austenite microstructure evolution processes occurring in line-pipe steels under hot rolling

70%

Rudskoy A. I. , Vasilyev A. , Kolbasnikov N. , Sokolov S. , Sokolov D.

Hutnik, Wiadomości Hutnicze

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2011

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tom Vol. 78, nr 5

415--420

EN

An experimental study of the processes of austenite microstructure evolution occurring under hot rolling was performed for line-pipe steels with different chemical composition. All investigations were conducted with the help of the Gleeble 3800 system. Empirical quantitative models of austenite grain growth, static and dynamic recrystallization, as well as a flow stress model were developed. The effect of complex alloying by such elements as C; Mn; Si; Ni; Mo; Nb; Ti; and V on grain growth and recrystallization is accounted for under the condition that all elements are in a solid solution.

PL

W pracy przedstawiono badania eksperymentalne ewolucji ziarna austenitu zachodzącej podczas walcowania na gorąco w stalach o zróżnicowanym składzie chemicznym, przeznaczonych na rurociągi dużych średnic. Wszystkie badania wykonano za pomocą systemu Gleeble3800. Opracowano empiryczne ilościowe modele rozrostu ziarna austenitu, statycznej i dynamicznej rekrystalizacji, jak również model naprężenia uplastyczniającego. Wpływ dodatków stopowych pierwiastków: C; Mn; Si; Ni; Mo; Nb; Ti i V na rozrost ziarna i rekrystalizację uwzględniono przy założeniu, że wszystkie dodatki znajdują się w roztworze stałym.