案例分析-气门

对凸轮轴进行了模拟试验，实现了新材料研发的快速筛选，出厂前成品的抽检等。大大提高了研发及生产效率，为发动机的性能提供了可靠的保证。

实现了新材料研发的快速筛选、出厂前的成品抽检以及众多供应商产品质量的统一，从根本上实现了体系化的质量管理，大大提高了产品合格率。

对产品进行模拟实验，实现了新材料研发的快速筛选，出厂前成品的抽检等。大大提高了研发及生产效率，为发动机的性能提供了可靠的保证。

Abstract The commercialattractivenessof rolls with greaterresistanceto wearandfatiguedamageis substantial.providing reducedrolling mil down times. increasedroll life. reducedproductsurfacedefectsand improvedstockgaugetolerances.Relatively little is known about1&' wearmechanismsof thesematerialswhich limit the usefullife of cold rolling mill work rolls.Two steelsof composition0.8%C/3%Craid 0.8%C/5%Cr. which are representativeof industry standardmaterials.havebeentestedin a rolling-sliding configuration (slippage.8C1t-againsta high speedsteel (M2) counterface.A comparisonhasbeenmadebetweensamplesmanufacturedby conventional processiDl (castingandforging) andby sprayforming. Sprayforming provideda microstructuresimilar to thatof the heavilyforged materialbutwitJt afiner averagecarbidesize (134 nm in thesprayformedand317nm in theforged,bothfor the3%Crsteels)andthesprayformedmaterill did not containthe occasionalcoarsecarbides( - 2 ~m) found in theforgedmaterial.The increasein Cr contentfrom 3% to 5%changed thecarbidefrom (Fe.Cr)3C (3%Cr steel) to (Fe.Cr)7C3(5%Crsteel) in bothsprayformedandforgedmaterials.However.boththe~ sizeandcarbidetype hadlittle effectonwearratewhentestedin thequenchedandtemperedcondition.Temperingof thequenchedsteelwa.s; undertakenin thetemperaturerange200-500 °c. which yieldedhardnessin the range540-890 H. for the 3% Cr steeland470-880 H. fIX" the 5% Cr steel. The wear coefficient decreasedsignificantly for an increase in hardnessfrom to 470 H.(k-l.72X 10-5mm3 N-1 m-l) ~ 750 H. (k-l.35X10-6 mm3N-1 m-l)but only fell slightly for hardnessvaluesabove750 H.. The friction coefficient was0.49-0.6.1': irrespectiveof loador materialtemper.Characterisationof worn surfacesindicatedthatsurfacestrainwaslimited to adepthof - 5-15 ~