31 research outputs found
Hybrid Rolling Bearings
Tlre preserrce oflrarrl corrtarnir~rrrIt.s in lubricated rolling bearing.~ is (I rrrrijor cr1~1.s ~ of /~rel~rrrti~re failure, for exarnple by fatigue or I J rrbr(r.sive ~ rt~erlr of rolling el en rent.^, races or cages. However; tlre brtrotluctiorr of rtruclr Irorcler ceranzic (u.sually silicon nitride) balls or r01ler.s rurrrrirrg rlgnirzst steel races, in tlre lzybrid bearing concept, is likely to clrarrge the inreracrior~.s of hard particulate co~rtorrrirrarrt.s wit11 tlre bearing corirporrents. TIre pefir~ncr~rce of crll-steel and hybrid rollirzg bearings was irrl)estigated irr tlre preserrce of two well-dejinerl particulate contcrr~rirrc~~rt.s. Experi~ne~rts were carried out with grease-lubricated tlrrrr,st berrrirrgs, contaminated with titorlia (rrnatase) and silica (quartz) particles. A.sigrIificur~r herreficial effect was observed in tlre hybrid beori~rgs irr tlre presence offine (<5 pm) arratase particles, as lower crrge werrr N I I running ~ temperature were recorded. Tlris ir~rproverrrerrt wt1.s nssocioted with the formation of thin and relatively soft titr~rrio fi11n.s on the silicon nitride hall surfaces. Irr tlre (111-steel berlrings, silica 17article.s caused severe wear of tlre bal1.s CIII( / crrge, whereas in /Ire hybrid becrring no wear could be detecterl on the l~all.s, nrrri cage wear was sigr~ificantly lower tlrrrrr for tlre (111-steel 6ecrrir1g. T11e wear losses of the steel racewcrys were si~itilur in hot11 cases
Reliable Compression of Sour and other Process Gases - Special Rolling Bearings for Oil-flooded Screw Compressors
Case StudyThis case study on oil-flooded screw compressors briefly covers: 1. Basic designs of oil-flooded screw compressors 2. Process layouts 3. Failure modes for conventional bearings seeing: Water condensing Sour (H2S) and Acid (CO2) gases; Water condensing Hydrogen-rich process gases. 4. âSour gas rolling bearingsâ consisting of: Super-tough stainless steel bearing rings; Bearing grade silicon nitride ceramic rolling elements; Glass fiber reinforced polymeric PEEK cages 5. A âservice-life diagramâ vs. H2S and CO2 mol
Konstruktion av bÄtinredning : Framtagning av ett bÄtpentry för Nimbus
I denna rapport presenteras ett examensarbete dÀr syftet Àr att komma pÄ en lösning till ett bÄtpentry dÀr kunden som köper bÄten ska kunna anpassa sitt pentry med att vÀlja olika kombinationer pÄ vad kunden sjÀlv vill ha i sitt bÄtpentry. Arbetet har utförts tillsammans med uppdragsgivaren Christian Dejevik, konsult pÄ C Dejevik Engineering AB dÀr han konstruerar fritidsbÄtar för modern bÄtproduktion. Han i sin tur har fÄtt uppdraget frÄn Nimbus Boats Sweden AB dÀr jag har suttit pÄ deras kontor i Göteborg och arbetat med projektet. Examensarbetet har i sin tur genomförts pÄ Högskolan i Halmstad under vÄren 2016 och omfattar 7.5 högskolepoÀng. MÄlet med detta projekt Àr att utifrÄn det valda konceptet ta fram en lösning till Nimbus problem gÀllande kundanpassningen pÄ bÄtpentryt som ska kunna passa in i en ny nimbusbÄt. Produkten ska i sin tur designmÀssigt passa in i bÄten och med den resterande inredningen som redan finns sÄ att hela bÄten bildar en helhetskÀnsla dÀr kunden ska kÀnna sig som hemma. Arbetet inleddes med ett möte med uppdragsgivaren dÀr idéer bollades för att sÄ tidigt som möjligt komma pÄ lite olika idéer pÄ hur man snabbt och pÄ bÀsta sÀtt skulle kunna komma vidare pÄ detta projekt. Under projektets gÄng sÄ har en konstruktionsmetod anvÀnts vilket har lett projektet framÄt i rÀtt riktning. En prototyp i datormiljö har skapats i programvaran SolidWorks dÀr produkten Àven anpassats tillsammans med den resterande bÄten. Renderingar har gjorts i SolidWorks och Keyshot 5. Photoshop har anvÀnts för finjusteringar pÄ bilderna. NÄgra av de fÀrdiga ritningarna som kan anvÀndas vid en eventuell tillverkning Àr bifogade i rapporten
Engineering Ceramics for Tribological Systems. Manufacture, Properties and Testing
A broad range of commercial and experimental grades of ceramics and ceramic composites was tested in various model tests and simplified component tests. The tests were done to establish important microstructural features, friction and wear mechanisms. Important tribological systems used in the tests included face seals, abrasive-waterjet nozzles and hybrid bearings. The importance of mechanical and physical properties at the micro-level has been highlighted in the work, as they play vital roles in the tribology of ceramics and are less commonly investigated than the bulk properties. Novel ceramic whisker composites were produced by hot-isostatic-pressing. The composites were based on a silicon nitride matrix reinforced with silicon carbide whiskers. The matrix of silicon nitride showed high strength and fracture toughness. But the composites showed no improvements in the bulk mechanical properties when compared with the matrix. This was mainly due to impurities in the whisker batch, causing defects and lower fracture toughness. A new type of silicon carbide material was made dense using liquid-phase sintering, and its wear behaviour was established and compared with conventionally solid-state sintered silicon carbides. The presence of grain boundary phases was both an advantage and a disadvantage regarding wear rates. At high wear rates the grain boundary phase limits the severity, probably due to crack deflection of the micro-fractures that occur. However, in mild wear the limited high-temperature properties of the grain boundary phases can be a disadvantage. Monolithic ceramics and composites with similar mechanical and physical properties to the bulk showed dramatically different wear behaviour in the tests. A newly developed, more homogeneous grade of whisker reinforced alumina showed superior wear resistance to the other monolithic ceramics and composites that were considered. A high-speed abrasive-waterjet test was developed in the work for wear testing, and was used to investigate the resistance of ceramics to thermal wear. The wear was caused by thermal spalling, oxidation, creep and plastic deformation. Abrasive-waterjet tests were done at low inclination angles, and newly commercialized machines were used. The tests highlighted the influence of thermal wear in the mixing nozzle for the abrasive and the waterjet, and the thermal mechanisms present while machining engineering ceramics. It was previously not known that an abrasive waterjet creates a thermal zone when machining ceramics at the wear front and in the mixing nozzles. The temperatures reached in the wear zone of the test specimens were at least 1280\ub0 C for the garnet abrasive, and 2050\ub0 C for the alumina abrasive. In scratch testing with diamond tips the presence of four different wear regimes was established for ceramics. On the tested materials a transition was seen from entirely ductile deformation at low loads, towards catastrophic brittle fractures at high loads. In scratch testing some materials, such as a hot-isostatic-pressed silicon nitride composite, showed much higher resistance to the initiation of brittle fracture. Ceramic composites reinforced with long fibres were studied to rank their sensitivity to particle impact. The test showed that composites with silicon carbide spheres on the surface were more resistant to the impact of abrasive particles. The spheres were present from the manufacturing process (chemical vapour infiltration). A study of thrust bearings was performed to compare all-steel bearings with hybrid ones. The hybrid bearing was of the same type as the all-steel one except the balls were of silicon nitride. The influence of contaminants in the bearings was investigated for fairly soft micron-sized (0.1-5.my.m titania) and macro-sized (75 100 .my.m quartz) ceramic contaminants. The hybrid bearing showed greatly superior performance when contaminants were present compared to the traditional all-steel type of bearing. It was shown that it is even possible to reduce friction and wear in a hybrid bearing system by the introduction of micron-sized titania particles
Engineering Ceramics for Tribological Systems. Manufacture, Properties and Testing
A broad range of commercial and experimental grades of ceramics and ceramic composites was tested in various model tests and simplified component tests. The tests were done to establish important microstructural features, friction and wear mechanisms. Important tribological systems used in the tests included face seals, abrasive-waterjet nozzles and hybrid bearings. The importance of mechanical and physical properties at the micro-level has been highlighted in the work, as they play vital roles in the tribology of ceramics and are less commonly investigated than the bulk properties. Novel ceramic whisker composites were produced by hot-isostatic-pressing. The composites were based on a silicon nitride matrix reinforced with silicon carbide whiskers. The matrix of silicon nitride showed high strength and fracture toughness. But the composites showed no improvements in the bulk mechanical properties when compared with the matrix. This was mainly due to impurities in the whisker batch, causing defects and lower fracture toughness. A new type of silicon carbide material was made dense using liquid-phase sintering, and its wear behaviour was established and compared with conventionally solid-state sintered silicon carbides. The presence of grain boundary phases was both an advantage and a disadvantage regarding wear rates. At high wear rates the grain boundary phase limits the severity, probably due to crack deflection of the micro-fractures that occur. However, in mild wear the limited high-temperature properties of the grain boundary phases can be a disadvantage. Monolithic ceramics and composites with similar mechanical and physical properties to the bulk showed dramatically different wear behaviour in the tests. A newly developed, more homogeneous grade of whisker reinforced alumina showed superior wear resistance to the other monolithic ceramics and composites that were considered. A high-speed abrasive-waterjet test was developed in the work for wear testing, and was used to investigate the resistance of ceramics to thermal wear. The wear was caused by thermal spalling, oxidation, creep and plastic deformation. Abrasive-waterjet tests were done at low inclination angles, and newly commercialized machines were used. The tests highlighted the influence of thermal wear in the mixing nozzle for the abrasive and the waterjet, and the thermal mechanisms present while machining engineering ceramics. It was previously not known that an abrasive waterjet creates a thermal zone when machining ceramics at the wear front and in the mixing nozzles. The temperatures reached in the wear zone of the test specimens were at least 1280\ub0 C for the garnet abrasive, and 2050\ub0 C for the alumina abrasive. In scratch testing with diamond tips the presence of four different wear regimes was established for ceramics. On the tested materials a transition was seen from entirely ductile deformation at low loads, towards catastrophic brittle fractures at high loads. In scratch testing some materials, such as a hot-isostatic-pressed silicon nitride composite, showed much higher resistance to the initiation of brittle fracture. Ceramic composites reinforced with long fibres were studied to rank their sensitivity to particle impact. The test showed that composites with silicon carbide spheres on the surface were more resistant to the impact of abrasive particles. The spheres were present from the manufacturing process (chemical vapour infiltration). A study of thrust bearings was performed to compare all-steel bearings with hybrid ones. The hybrid bearing was of the same type as the all-steel one except the balls were of silicon nitride. The influence of contaminants in the bearings was investigated for fairly soft micron-sized (0.1-5.my.m titania) and macro-sized (75 100 .my.m quartz) ceramic contaminants. The hybrid bearing showed greatly superior performance when contaminants were present compared to the traditional all-steel type of bearing. It was shown that it is even possible to reduce friction and wear in a hybrid bearing system by the introduction of micron-sized titania particles
Gröna transporter inom dagligvaruhandeln
Bakgrund: Att miljöfrÄgan idag Àr ett omtalat och omdiskuterat Àmne rÄder det inga
tvivel om. Till följd av denna uppmÀrksamhet av den omfattande klimatpÄverkan som
förekommer har allt större krav pÄ företag och deras arbete inom omrÄdet uppkommit.
Ăven kundernas miljökrav har en stor inverkan pĂ„ hur man verkar inom detta omrĂ„de.
Trots denna uppmÀrksamhet kring den gröna logistiken samt studiers pÄvisande pÄ
dess vitalitet förekommer det idag företag som inte alls, eller endast till en liten del,
Àgnar sig Ät dessa frÄgor.
Syfte: Syftet med följande studie Àr att undersöka vilka miljömÀssiga krav och
förvÀntningar en dagligvarugrossists kunder har gÀllande godstransporter samt vilka
ÄtgÀrder ett företag kan genomföra för att miljöeffektivisera sina transporter. För att
undersöka detta har fallföretaget Piwa Food AB valts att studeras.
Metod: Följande studie bygger pÄ en kvalitativ fallstudie med en abduktiv
forskningsansats. PrimÀrdata har samlats in i form av semistrukturerade intervjuer
med fallföretaget, tre kundföretag samt en intresseorganisation. SekundÀrdata har
hÀmtats utifrÄn etablerade teorier samt material insamlade av andra forskare i form av
vetenskapliga rapporter i syftet att syntetisera samt sammanfatta rÄdande forskning.
Teoretisk referensram: I den teoretiska referensramen beskrivs transporternas
miljöpÄverkan idag samt metoder som kan tillgÄs för att reducera de miljöfarliga
utslÀpp som de bidrar till. Det redogörs Àven för vad miljömÀssiga transportinköp
innebÀr och hur ett företags kunder kan pÄverka hur dessa genomförs. Ytterligare
beskrivs det hur relationen mellan kund och leverantör samt kundens roll som
intressent har en pÄverkan pÄ huruvida företag vÀljer att miljöeffektivisera sina
verksamheter.
Resultat: Resultatet i studien utgörs av intervjuer med respondenter frÄn ICA, Martin
& Servera, Bergendahls, NÀtverket för transporter och miljö samt frÄn fallföretaget. I
resultatet framkommer information kring de olika omrÄdena som berör
företagsbeskrivning, miljö, drivkrafter bakom ett miljöarbete, inköp och framtiden.
Resultatet visar pÄ att detaljister inom dagligvaruhandeln idag lÀgger stort fokus pÄ
miljöfrÄgan och arbetar för att miljöeffektivisera inom stora delar av verksamheten.
Vad gÀller grossisternas transporter förekommer dock inga miljömÀssiga krav pÄ hur
dessa skall genomföras.
Slutsats: UtifrÄn studien har det kunnat faststÀllas att detaljisterna, trots dess uttalade
miljömedvetenhet, inte stÀller nÄgra miljökrav pÄ dagligvarugrossisternas
godstransporter idag. Vad gÀller framtida miljömÀssiga krav kan man baserat pÄ svar
frÄn samtliga respondenter i studien dra slutsatsen att krav kring transporterna
kommer att stÀllas framöver. Vidare ges exempel pÄ hur man kan miljöeffektivisera
sina transporter.
Förslag till vidare forskning: DÄ miljöfrÄgan Àr ett omdiskuterat Àmne vore det
intressant att se hur denna debatt Àndras över tiden. I denna studie pekas det pÄ att
kunder idag inte stÀller miljökrav pÄ sina leverantörer med avseende pÄ transporter,
men att det förutses komma i framtiden. Med hÀnsyn till detta vore det tÀnkvÀrt att
genomföra en liknande studie om ett antal Är för att se om kraven verkstÀlls. Ett annat
förslag Àr att vidareutveckla studien med utgÄngspunkt i företagets övriga intressenter
Exteriördesign av miljöbil
Sedan ett Är tillbaka pÄ företaget Elitkomposit AB pÄgÄr ett fordonsprojekt som syftar till att ta fram konstruktionsunderlag för en fyrhjulig miljöbil för tvÄ passagerare och hundra liter bagage. Bilen ska byggas huvudsakligen i kompositmaterial. Syfte och mÄl med arbetet Àr att presentera ett nytt sportigt karosskoncept som ska vara en blandning av ett segelflygplan, formel 1 bil och en stridslysten krÀfta. Förhoppningarna Àr att Elitkomposit kommer uppskatta den nya designen och anvÀnda sig av den nÀr dem senare tillverkar miljöbilen. Endast bilens exteriördesign kommer att formges och presenteras till Elitkomposit AB. Arbetet Àr designinriktat och ingen hÀnsyn till fordonsbestÀmmelser eller teknisk funktion kommer att tas i beaktande. För att lösa uppgiften skapades först en idébas, Ätta koncept valdes sen ut för att genomgÄ en concept screening. Fem koncept gick vidare till en concept scoring dÀr tre koncept gick vidare. Slutligen valdes tillsammans med Elitkomposit ett vinnande koncept som konstruerades i NX och sedan renderades i Alias. Det slutgiltiga konceptet infriar de krav Elitkomposit uttalat med undantag av att den ska liknas vid en krÀfta. För att bilen ska fÄ en mer aggressiv framtoning har den istÀllet fÄtt influens av en stridslysten skorpion i attackstÀllning