Wyniki wyszukiwania - Biblioteka Nauki

1

Study on structures and properties of the laser cladding exhaust valve after service

100%

Kończewicz W. , Krużycki P. , Smoleńska H.

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tom Vol. 17, No. 3

211-216

EN

The cobalt base laser cladding layers which were built up on the exhaust valve head face of the heavy loaded marine diesel engine have been investigated. The valve head with cladded face were served successfully for 3000 hours in the engine of the Dar Młodzieży. After removing from the valve head from the cylinder head the face surface were fully inspected. The surface topography and roughness were evaluated. Microstructure on the cross section of the clad layer were analyzed using Scanning Electron Microscope (SEM) equipped with energy dispersive spectroscopy (EDS. Also microhardness of the clad layer was measured. The service conditions resulted with the formation of the scale which had different thickness and tended to cracking and spalling. The microstructure of the clad layers after service did not demonstrated serious degradation process. The decrease of the hardness numbers was observed but still clad layer presented higher hardness than steel base. This type of clad layer underwent intensive laboratory examinations which contained oxidation experiments at different temperatures and corrosion in exhaust gases, long time exposition in laboratory engine and in the end 3000 hours successfully service on the ship. After such experience laser cladding cobalt base layers may be recommended as a useful solutionfor both prolongs of the service life and a method of the regeneration of the slightly used valve heads is suitable for practical applications.

2

Behaviour of the exhaust valve cladding face under the service conditions

100%

Kończewicz W. , Smoleńska H.

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tom Vol. 16, No. 1

265-271

EN

During the ship engine operation one of the key problems is the exhaust valve durability. A special interest is in valve head face because this narrow part of the valve is responsible for tightness. Cobalt base laser cladding layer on the exhaust valve head face have been investigate under real service condition using the laboratory two-stroke diesel engine L22 for two years. During this time the engine was fuelling with both ordinary light fuel and biodiesel fuel. After removing from the valve head from the cylinder head the face surface were fully inspected optically. There were no damages and the surface was shining in the great deal however some dark "spots " on it. The samples made of the used valve head underwent microstructural investigation and hardness measurements. There were no observed substantial microstructural changes neither in the surface of the layer nor in the bulk of the clad. The decrease of the hardness numbers was observed but still clad layer presented higher hardness than steel base. This type ofclad layer underwent intensive laboratory examinations which contained oxidation experiments at different temperatures and corrosion in exhaust gases and with the present service experiment this method of valve head hard facing is suitable for practical applications.

3

The Impact of Material Selection on Durability of Exhaust Valve Faces of a Ship Engine – A Case Study

75%

Smoleńska H. , Kończewicz W. , Bazychowska S.

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tom Vol. 14, no 3

165--174

EN

Two alloys were used in order to extend the service life of marine engine exhaust valve head. Layers of cobalt base alloys were made of the powders with chemical composition as follow: the layer marked L12; C-1.55%; Si-1.21%; Cr-29.7%; W-9%; Ni-2%; Mo<0.01%; Fe-1.7%; Co-54.83% and the layer marked N; C-1.45%; Co-38.9%; Cr24.13%; Ni-10.43%; W-8.75%; Fe-7.64%; Mo-7.56%; Si-2.59%. Base metal was valve steel after heat treatment. It was consisted of: C-0,374%; Cr-9,34%; Mn-0.402%; Ni-0.344%; Si-2.46%; Mo-0.822%; P-0.0162%; S-0.001%. Layers on the valve faces were produced by laser cladding using the HPDL ROFIN DL020 laser. Grinding treatment is a very popular form of regeneration of seat and valve plug adhesions. Properly performed grinding operation ensures dimensional and shape accuracy of the surface from 7 to 5 accuracy class and surface roughness Ra not less than 0.16 μm, depending on the object and method of grinding. The 75H and 150S types are a significantly simplified form of valve plug face grinders. Finishing treatment was carried out with a Chris-Marine AB75H sander on a sanding stand equipped with a compressed air system - the stand was designed by the author. The sander has been set up to the surface of the valve stem so that the grinding angle of the valve faces is 30°+10°. A flat grinding wheel T1CRA54–K was used for machining. The plunge feed was 0.01 mm/rev. The thickness of the welded layer after grinding was 1.2 mm. Both valves were installed in the ship’s engine and were used in real life. After 2000 hours of operation, the valve marked N was damaged. The valve marked L12 showed no damage and was in operation for the next 1000 hours.

4

Modelowanie pola temperatur zaworu wylotowego doładowanego silnika z zapłonem samoczynnym w stanie nieustalonym

63%

Gustof P. , Jędrusik D.

Zeszyty Naukowe. Transport / Politechnika Śląska

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2003

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tom z. 50

15-22

PL

W pracy wyznaczono pola temperatur zaworu wylotowego doładowanego silnika z zapłonem samoczynnym w stanie nieustalonym przy zastosowaniu modelu dwustrefowego procesu spalania oraz metody elementów skończonych (MES) za pomocą programu Cosmos/M.

EN

The thesis determines fields of temperatures the exhaust valve of Diesel turbo engine in an unsteady state performed using model of process of two-zone combustion and the finite elements method (MES) with support of programme Cosmos/M.

5

Hardness prediction of a cold rolled Nimonic 80A exhaust valve spindle

63%

Kang S. W. , Heo S. J. , Yoo J. H. , Kang J. H.

Journal of Achievements in Materials and Manufacturing Engineering

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2019

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tom Vol. 94, nr 1-2

13--21

EN

Purpose: of this paper is to predict the hardness of cold rolled exhausts valve spindle fabricated of Nimonic 80A via axisymmetric finite element analysis, compression testing, and hardness inspection. Design/methodology/approach: The stress-strain relationship of Nimonic 80A was obtained via compression testing with deformation ratios of 10%, 20%, and 30%. Hardness changes caused by the strain hardening effect were measured in cut specimens in both the axial and circumferential directions following compression testing. The effective strain at the measurement position was calculated via finite element analysis. The regression equation for hardness changes caused by work hardening was derived from analysed strain and inspected hardness. The cold-rolling deformation of an exhaust valve spindle was analysed using axisymmetric finite element analysis. Findings: The stress-strain relationship calculated from compression testing was well expressed using the Holloman equation and the strain-hardness relationship by strain hardening was successfully regressed using the shifted power law model for Nimonic 80A, Nickel-Chromium based super alloy. Research limitations/implications: This research focused hardness prediction of spindle after ring rolling operation for generating beneficial compressive surface residual stresses for enhancing fatigue life. Further research to quantify compressive residual stress after rolling shall be followed to increase fatigue life. Practical implications: The cold rolling process is a typical incremental forming method and should be analysed under three-dimensional conditions. However, it takes lots of time to solve incremental forming analysis. To predict hardness distribution after rolling in the manufacturing field, FE analysis was performed under two-dimensional axisymmetric conditions based on the assumption of no friction generated by the rolling tool. The deformed shapes and hardness distribution from the inspection quality standard and two-dimensional FE analysis showed very similar results. Simplified finite element analysis method for ring rolling process for local area could be very effective method in the industrial field. Originality/value: The stress-strain relationship and the hardness and strain relationship were derived by compression test and hardness measurement for compressed specimen for Nimonic 80A, Nickel-Chromium based super alloy. And simplified finite element analysis method was suggested to predict deformed shape and hardness distribution of locally cold rolled region and achieved similar result between FE analysis result and Quality standard. Suggested method would be very effective method to engine spindle manufacture to predict hardness of different size of product.

6

Analiza numeryczna przyczyn uszkodzeń głowicy i zaworów silnika o zapłonie samoczynnym

63%

Hejwowski T. , Dębski H. , Koszałka G.

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tom R. 50, nr 3

PL

W pracy przedstawiono wyniki obliczeń numerycznych wykonanych metodą elementów skończonych rozkładów naprężeń, temperatury i przemieszczeń. Rozpatrywanym silnikiem był wolnossący silnik o zapłonie samoczynnym typu 4C90. Obliczenia wykonano przy pomocy programu ABAQUS/Standard. Rozważanymi elementami silnika były zawory dolotowy i wylotowy oraz głowica. Wyniki analiz numerycznych identyfikują mechanizm uszkodzenia głowic jako zmęczenie niskocyklowe spowodowane cyklicznym włączaniem i wyłączaniem silnika i poprawnie określają lokalizację pęknięć. Rezultaty obliczeń udowodniły, że występuje znaczny poślizg na powierzchni kontaktu grzybka i gniazda, co jest spowodowane wzajemnym przemieszczeniem gniazd i zaworów i jest przyczyną zużywania adhezyjnego. Wysoka temperatura powierzchni przylgni zaworu wylotowego powoduje intensywną korozję. Przeprowadzone obliczenia numeryczne umożliwiają szczegółową analizę przyczyn uszkodzeń silnika ZS.

EN

In the paper, the results of FEM calculations of stress, temperature and displacement distributions are presented. The considered engine was naturally aspirated diesel engine of 4C90 type. The numerical calculations were performed by means of ABAQUS/Standard software. The considered elements of the engine were cylinder head, inlet and exhaust valves. The results of numerical analysis identify mechanism of failure of cylinder head as low cycle fatigue caused by cyclic switching on and off the engine and provide precisely locations of cracks. Results of calculations proved that there is the considerable slip at the surface of contact of valve with valve insert, which is caused by the relative displacement of valves and inserts. It is the cause of adhesive wear. High temperature of exhaust valve surface accelerates corrosion. The carried out numerical calculations enable to analyze in detail failure causes of diesel engine.

7

Diagnozowanie uszkodzenia zaworu wylotowego silnika spalinowego na podstawie analizy falkowej drgań

63%

Komorska I. , Stanik Z.

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tom R. 50, nr 3

PL

W referacie zaproponowano metodę diagnozowania nieszczelności zawór wylotowy - cylinder w oparciu o pomiar sygnału drgań głowicy silnika. Przedstawiono wyniki analizy pomiarów sygnału drgań silnika w warunkach uszkodzonego zaworu wylotowego silnika oraz niewłaściwego luzu zaworowego. W tym celu przeprowadzono czynny eksperyment diagnostyczny na silniku samochodu Fiat Punto 1.2. W czasie testów drogowych zarejestrowano sygnał przyspieszenia drgań, a także pomocnicze sygnały służące synchronizacji oraz identyfikacji faz rozrządu. Wykorzystano przy tym naturalne wzmocnienie drgań w zakresie częstotliwości rezonansowej czujnika piezoelektrycznego. Zadowalające rezultaty uzyskano w oparciu o analizę falkową sygnału przyspieszenia drgań silnika. Wyznaczono miary sygnału w jednoznaczny sposób określający stan zaworu. Metoda jest nieinwazyjna, a badania przeprowadzane są w warunkach eksploatacyjnych. Z pewnymi modyfikacjami metoda może być zastosowana do diagnozowania zaworów on-line.

EN

The paper proposes the method of diagnosing of cylinder exhaust valve leakage based on the measurement of the cylinder head vibration signal. The results of vibration signal analysis of the engine with the damaged exhaust valve and with changed exhaust valve clearance are presented. In this purpose the diagnostic experiment was carried out with car engine Fiat Punto 1.4. During road test the acceleration vibration signal was recorded with additional signals for synchronization and engine timing. The natural amplification of vibration at the range of resonance frequency of the piezoelectric sensor was used. Satisfactory results were obtained based on wavelet analysis of engine vibration signal. The measures of signal were determined that allow determination of the valve condition. This is the non-invasive method and the investigations are conducted during car maintenance. With some modification the method can be used for on-line diagnosis of the exhaust valves.

8

Numeryczna analiza naprężeń w zaworze wydechowym silnika tłokowego pracującym w warunkach obciążenia termo-mechanicznego

63%

Witek L.

Logistyka

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2015

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tom nr 4

6681--6688, CD2

PL

Niniejsza praca opisuje wpływ różnych rodzajów obciążeń na rozkład naprężeń zaworu grzybkowego silnika z zapłonem samoczynnym. W celu rozwiązania zdefiniowanego problemu naukowego zbudowany został model geometryczny oraz uproszczony model dyskretny układu zaworowego. W pracy uwzględniono dwa rodzaje obciążeń: mechaniczne (od siły ugięcia sprężyny, po zamknięciu zaworu) oraz cieplne (od nierównomiernego nagrzania) W pierwszej części pracy analizowano przypadki obciążeń działających niezależnie, co pozwoliło na ocenę wpływu obciążeń składowych na poziom wytężenia materiału zaworu. Rezultaty analizy numerycznej wykazały, że największy wpływ na poziom naprężeń w zaworze ma obciążenie termiczne wynikające z niejednorodnego pola temperatury. W pracy analizowano także naprężenia pochodzące od wszystkich obciążeń działających równocześnie. W ostatniej części pracy sformułowano wnioski końcowe oraz wskazano kierunki dalszych badań.

EN

This paper presents the influence of different kinds of loads on the stress distribution in the valve of combustion engine. In order to solve the research problem, both the geometrical and the discrete model of valve system were defined. Two types of load were taken into consideration: the mechanical load (from valve spring, after valve close) and the thermal load (from non-uniform temperature distribution). In first part of work a separated loads were considered. Results of numerical analysis showed that the most significant influence on the stress levels in the valve has the thermal load related to non-uniform temperature field. In the last part of work the influence of complex thermo-mechanical load on stress state of valve were considered. Results of work showed that the operational stress has a small values. In summary of the work an interesting conclusions were formulated.

9

Wpływ nadmiaru powietrza na temperaturę gazów spalinowych za zaworem wydechowym i przed katalizatorem

63%

Fabiś P.

Zeszyty Naukowe. Transport / Politechnika Śląska

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2004

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tom z. 56

155-160

PL

W opracowaniu przedstawiono wpływ zmiany współczynnika nadmiaru powietrza na temperaturę gazów spalinowych przy zasilaniu silnika paliwem LPG. Pomiarów dokonano za zaworem wydechowym a przed katalizatorem.

EN

The paper presented influence of the Air/Fuel ratio on the exhaust gas temperature when the engine is reinforce by LPG. The temperature was measure behind the exhaust valve and before catalyser.