机械 液压 外文翻译 外文文献 英文文献 水基液压系统

水基液压系统传统上水基液压系统已经应用在钢铁厂炼铁领域。这些产业中水基液压系统的明显的优点是它们的耐火性。而且水基液压系统在费用上也优于油基的液压系统。首先，无毒的、可被生物分解的综合性添加剂每加仑花费5到6美元。一加仑集中可生成20加仑的5%溶液，因此实际上水基液压流体的费用可以比油基的每加仑少30分。在工厂的水平下，考虑到相关费用、防止和清理环境的污染，水基液压系统拥有节省巨大本钱的潜力。液压油的泄漏已经成为一个非常重要的问题。它必须被收集、妥善控制。不过，含有合成添加剂的水，可以倾倒入工厂的污水系统。'j,L,~(D2b9O(l*`在工厂水平下，节省本钱不停留在流体的较低本钱及其处理上。因为水基液压液由十局部水和一部份合成添加剂，5加仑添加剂与水的混合物构成100加仑水基流体。50加仑的容器当然比两个55加仑的桶更容易处理，因此储藏更简单、更清洁、更不凌乱，运输本钱也较低。.J0_7]2i:Z#a其他工厂范围下潜在的节约是为工人改善平安，因为水基液是不含毒性，并且非易燃。这些特点可以减少工厂的保险费率。泄漏的本钱比清理低，因为不再需要颗粒吸收剂或吸附棉条。水基流体再次变成“热门话题〞3u#Y3l+s&r,D9Q在20世纪70年代石油禁运引发了较低本钱的水基液压流体替代高昂的液压油的兴趣。当 设计 领导形象设计圆作业设计ao工艺污水处理厂设计附属工程施工组织设计清扫机器人结构设计 师们得悉，一加仑聚合物可以制造出二十加仑的流体时，即使是最昂贵的水添加剂都更有吸引力。$O!e2?;L"d;J由于石油价格逐渐的回落，因此人们对水基液压也没有那么大的兴趣了。回想起来，对水基流体的兴趣集中在其节省本钱的潜力上。当设计师发现他们不能在他们的系统中改变流体从液压油到水的状况并且也没有其他重大的改变时，他们就失去了兴趣。然后，他们不情愿的接受其他的“缺点〞–了解到很大的变化-又切换到水基液压。适用于水基液压系统的不同的规那么被认为是缺点。设计师可能不愿意学习更多关于水基液压，因为他们被暗示，所有的工作需要依靠如何设计一个新的系统或改造旧系统的知识。因为他们结束了对这另外技术的思维，他们错过了除水基流体初始本钱以外的许多其他的优点。现在，环境问题，增加了液压油处理本钱的价格，水基液压便再次成为热门话题。,m5N*S3N3D:y5I6o抵抗凝固.`7D)m#h)t*k8A当然，水基液压系统确实在应用上有它的局限性。一个限制就是潜在的凝固。这个可能性可能是更广泛地应用水基系统，特别是在移动设备业最重要的阻碍。长壁开采法是迄今为止最大的能够充分利用水基系统的移动设备部门。地下的温度不接近水的凝点和耐火性是必不可少的条件。用于温带气候海上设备和移动设备获利于水基系统的优点，但不能保证这些设备将始终用在上述凝固温度。不过，给水基流体参加防冻液可以使其凝固温度远低于32华氏度。用在汽车上的防冻液-乙二醇-是有毒的，是不能生物降解的，因此它在水基液压中添加防冻液将击败水基液压流体在环境上的优势。7V:O)N2T1H/S有一个替代的 方法 快递客服问题件处理详细方法山木方法pdf计算方法pdf华与华方法下载八字理论方法下载 。丙二醇是没有毒性，而且是可生物降解的。它比乙二醇花费更多，并且是不太有效的一种防冻液，因此它必须使用较高浓度的溶液。减少凝固潜力的另外两个技术是要保持流体的不断循环和在实际中使用胶管。系统的密封水基液压系统的两个个容易被发觉的问题是细菌的大批出没，并且很难保持适当的浓度。大气下的密封系统在控制中可容纳细菌成长。此外，如果从系统排除空气，一个抗菌剂的流体能对防止细菌的增长有一个持久的影响。;X6A'l&k9u,aM1b:i(n一个被密封的水箱消除许多液压系统遭受的另一个问题：水的进入。这说明关于水基系统的另一个误解：没有从大气中密封的水基系统，必须密切监察，以确保该添加剂浓度保持在在允许的范围之内。这是因为水比添加剂更容易从水箱蒸发。因此，水分蒸发导致添加剂浓度增加。当新液体添加到系统时，现有的流体样本必须采取 措施 《全国民用建筑工程设计技术措施》规划•建筑•景观全国民用建筑工程设计技术措施》规划•建筑•景观软件质量保证措施下载工地伤害及预防措施下载关于贯彻落实的具体措施 ，以确定一定浓度的添加剂在溶液中。这些结果显示，添加剂在流体中的比例必须补充，使流体的浓度是适宜的。*?I;_+f:J'x+z与大气隔绝的密封的流体系统，实际上消除了蒸发问题。泄漏的液体是包含水和添加剂的。所以，系统液体的量在发生变化，但浓度没有变化。系统流体通过增加水和添加剂的一种预先混合重新补充到水箱。特殊的考虑:s&J"r(H1i/r/c如果水基液压系统没有正确的设计，他们可能更容易使水泵汽蚀。应提供通畅的通道，保持流体速度低于20英尺/秒，最好是在压力线低于15英尺/秒。在一般情况下，吸油管的速度，不应超过2-3英尺/秒。在回油管的速度应低于5到10英尺/秒。当流体再进入水箱时，较高的回油管速度可以促进发泡。零部件也应注意其规格，因为流体压力和速度急剧变化可能造成溶解气体和造成类似气蚀的损伤。对水基的系统的重要考虑是应该明确设计主要元件为水基流体所使用，而不是修改最初供油效劳的系统。油管，胶管，及配件，通常对这些油基液压系统可以相同。但是，水泵，阀，执行器和供水装置，存在着一些重大不同。例如，齿轮泵，应作出超硬合金抗磨损。泵的齿轮比一个油泵应更广泛，因为水的低粘度需要一个更大的范围，以形成一个足够的润滑膜。使用在水基系统中的缸应该有青铜做的活塞，以减少活塞和缸壁之间的磨损。弹簧或O型圈的密封用来减少活塞的渗漏。5_(z9]%i4Y,o'O水基液压阀%C0n)Gj5I,U5L!t+c)M水基的流体的阀通常是加了密封件，用于别离金属零件，以防止金属-金属接触。这是因为水-甚至与润滑油添加剂-没有提供完整的润滑油膜。水基装置用的阀的价格也有少许大于油基装置的。这可能是另一个原因，水基系统没有得到广泛的接受。本来，当设计系统时，面积较大的元件水基流体创立了一个障碍，并且更加昂贵的制造价格使水基液压阀的价格提高了3倍或更多。不过，现在阀大小和油基系统的相当。许多阀可到达美国国家防火协会标准。价格差异也较少。水基液压元件仍可能花费比油基系统高3％以上，但当考虑到水基系统节省本钱的潜力，这样做可能会得到更多的实惠。流体的泄露-h4t'a1W9[3u1q7]在许多液压系统中泄漏仍然是一个恼人的问题。新的密封材料及设计，及O型圈，是解决密封装置泄漏的功能强大的武器。由于误用，安装不当，或缺乏简单的了解，泄漏的问题仍未解决。虽然在大多数的系统中没有任何理由泄漏，但它仍然出现。假设不解决泄漏，在不久的将来，水基液可以大大降低泄漏的相关费用。!m6P1w9S/K*Q内部泄漏是很浪费的。这种泄漏能能使温度升高，从而使液压油碳化。内部泄漏通常是泄露回容器的，因此这一技术转化成机械能的热，这并不是有益的工作。在一个水基液压阀运动部件中采用不锈钢阀芯聚四氟乙烯密封。因为没有间隙，所以就不存在内部泄漏。2N,L5i(t#]但除了明显的和无形的液漏本钱外，处理已泄漏液体已经成为一个被人关注的问题。考虑到除去或取消本钱时，允许液压油进入污水厂系统成为一个昂贵的主张。实现这一清理和处置本钱只会上升，并且石油价格的不稳定说明，水基液压可以成为一个利于解决环境问题比拟经济的方法。Water-basedhydraulicsystemsWater-basedhydraulicsystemstraditionallyhavebeenusedinhot-metalareasofsteelmills.Theobviousadvantageofwatersystemsintheseindustriesistheirfireresistance.Water-basedhydraulicsystemsalsohaveobviouscostadvantagesoveroil-basedfluid.First,non-toxic,biodegradablesyntheticadditivesforwatercost$5to$6pergallon.Onegallonofconcentratecanmake20gallonsofa5%solution,sothecostofwater-basedhydraulicfluidactuallycanbelessthan30centspergallon.Consideringthecostsassociatedwithpreventingandcleaningupenvironmentalcontamination,water-basedhydraulicsystemsholdthepotentialfortremendouscostsavingsattheplantlevel.Oilthathasleakedalreadybecomesaveryimportantproblem.Itmustbecollected,properlycontained.Watercontainingsyntheticadditives,however,canbydumpedintoplanteffluentsystems.Costsavingsattheplantleveldon'tstopatthelowercostofthefluidanditsdisposal.Becausewater-basedhydraulicfluidconsistsof10partswaterandonepartsyntheticadditive,5gallonsofadditivemixeswithwatertomake100gallonsofwater-basedfluid.A50galloncontaineriscertainlyeasiertohandlethantwo55-gallondrums,sowarehousingissimpler,cleaner,andlesscluttered.Transportationcostsalsoarelower.5o:p#a6|%N!e!]Otherpotentialplant-widesavingsincludeimprovedsafetyforworkersbecausethewater-basedfluidisnon-toxicaswellasnon-flammable.Theseattributescanreduceplantinsurancerates.Spillscostlesstocleanupbecausegranularabsorbentsorabsorbentsocksareunnecessary.Wateris"hot"again#g#D"W*z4c8OTheoilembargointhe1970ssparkedinterestinwater-basedfluidsasaless-costlyalternativetooils.Eventhemostexpensivewateradditivesbecameattractivewhendesignerslearnedthatonegallonofconcentratewouldmake20gallonsoffluid."Y9y7q&?*d,rAsoilpricesgraduallydropped,sodidinterestinwater-basedhydraulics.Inretrospect,interestinwater-basedfluidscenteredaroundtheircostsavingpotential.Mostdesignerslostinterestwhentheydiscoveredthattheycouldnotjustchangethefluidintheirsystemsfromoiltowaterwithoutmakingothersubstantialchanges.Theythenbecomereluctanttoacceptother"disadvantages"-readsubstantialchanges-ofswitchingovertowater-basedhydraulics.&[4w:G,R)u#j7e4`+p._8IWhatwereviewedasdisadvantageswerereallydifferentrulesthatapplytowater-basedhydraulicsystems?Designersprobablyresistedlearningmoreaboutwater-basedhydraulicsbecausetheywereintimatedbyalltheworkrequiredtoleanabouthowtodesignanewsystemorretrofitanoldersystem.Byclosingtheirmindstothisdifferenttechnology,theymissedthemanyotheradvantagesofwater-basedfluidbeyondinitialcost.Nowthatenvironmentalconcernshaveaddeddisposalcoststothepriceofhydraulicfluids,water-basedhydraulicshasagainbecomeahottopic.Fightingfreeze9W,y+J4j0I8o6V-F9yWater-basedhydraulicsystemsdo,ofcourse,havelimitstotheirapplications.Onelimitationisthepotentialoffreezing.Thispossibilityisprobablythemostsignificantblockadetomorewidespreadapplicationofwater-basedsystems,especiallyinthemobileequipmentindustry.Longwallminingisbyfarthelargestsectorofmobileequipmentthathasbeenabletotakeadvantageofwater-basedsystems.Temperaturesundergrounddonotapproachthefreezingpointofwater,andfireresistanceisessential.Mobileandevenmarineequipmentusedintemperateclimatescouldcashinonetheadvantagesofwaterbasedsystems,butthereisnoguaranteethatsuchequipmentalwayswillbeusedinabove-freezingtemperatures.Nevertheless,addingananti-freezetoawater-basedfluidcandepressitsfreezingtemperaturetowellbelow32°F.Ethyleneglycol-usedinautomotiveanti-freeze-istoxicandisnotbiodegradable,soitsuseforanti-freezeinwater-basedhydraulicfluidwoulddefeattheenvironmentaladvantagewater-basedfluidhas.Thereisanalternative.Propyleneglycolisnottoxicandisbiodegradable.Itcostsmorethanethyleneglycolandisnotquiteaseffectiveantifreeze,soitmustbeusedinslightlyhigherconcentrations.Twomoretechniquestoreducefreezingpotentialaretokeepfluidcirculatingcontinuouslyandusehosewherepractical.Sealingthesystem9n$i$~a.V'i$U$u;JTwomoreperceivedproblemswithwaterhydraulicsystemsarebacterialinfestationanddifficultyinmaintainproperconcentrations.Sealingthesystemfromatmospherecanholdbacterialgrowthincheck.Additionofananti-bacterialagenttothefluidcanhavealastingeffectonpreventingbacterialbuildupifairisexcludedfromthesystem.'t!h0B8P1K:i&sAsealedreservoireliminatesanotherproblemsufferedbymanyhydraulicsystems:wateringression.Thisaddressesanothermisconceptionaboutwater-basedsystems:water-basedsystemsnotsealedfromtheatmospheremustbecloselymonitoredtoensurethattheadditiveconcentrationstayswithintolerance.Thatisbecausewaterevaporatesfromthereservoirmorereadilythantheadditivedoes.Consequently,waterevaporationcausestheadditiveconcentrationtoincrease.Whennewfluidisaddedtoasystem,samplesoftheexistingfluidmustbetakentodeterminetheconcentrationofadditiveinsolution.Theseresultsthenrevealtheratioofadditivetofluidthatmustbeaddedsothatfluidconcentrationiscorrect..p'z-\&v'N:n$^Withasystemthatsealsfluidfromtheatmosphere,theevaporationproblemisvirtuallyeliminated.Fluidthatescapesbyleakageisasolutioncontainingwaterandadditive.Therefore,thequantityoffluidinthesystemchanges,butconcentrationdoesnot.Systemfluidisreplenishedsimplybyaddingapre-mixedsolutionofwaterandadditivetothereservoir.3s1v6Y;v*SSpecialconsiderationsWater-basedhydraulicsystemscanbemorepronetopumpcavitationiftheyarenotproperlydesigned.Generousportingandotherpassagewaysshouldbeprovidedtokeepfluidvelocitiesbelow20ft/sec-preferably,below15ft/secinpressurelines.Velocityinsuctionlines,ingeneral,shouldnotexceed2-3ft/sec.Velocitiesinreturnlinesshouldbeheldbelow5-10ft/sec.Higherreturnvelocitiescanpromotefoamingwhenfluidre-entersthereservoir.Componentsshouldalsobecarefullysizedbecauserapidchangesinfluidpressureandvelocitycancausedissolvedairtoprecipitatefromsolutionandcausedamagesimilartothatproducedbycavitations.(m/n-q+u*`0X#XAnimportantconsiderationforwater-basedsystemsisthatmajorcomponentsshouldbedesignedspecificallyforusewithwaterfluid,ratherthanmodifiedfromversionsoriginallyintendedforoilservice.Tubing,hose,andfittingsusuallycanbeidenticaltothoseforoilsystems.Pumps,valves,andactuatorsforwaterservice,however,exhibitsomesignificantdifferencesfromcomponentsforoilsystems.Pumpgears,forexample,shouldbemadeofsuper-hardalloystoresistwear.Apump'sgearfaceshouldbewiderthanthatofanoilpumpbecausewater'slowviscosityrequiresalargerareatoformanadequatelubricantfilm.Cylindersusedinwatersystemsshouldhavebronze-cladpistonstominimizewearbetweenpistonsandcylinderwalls.Spring-orO-ring-energizedsealsshouldbeusedtominimizeleakageacrossthepiston.2d;Y-_.Z(t7^.@;W1HValvesforwaterValvesforwater-basedfluidusuallyarepackedwithsealsseparatingmetalpartstopreventmetal-to-metalcontact.Thisisbecausewater-evenwithlubricantadditives-doesnotprovidethefull-filmlubricationofoil.Metalsurfacesinrelativemotioninvalvesforwater-basedfluidareseparatedbybearing-typematerials.;x#g']8f0u-]Valvesforwaterservicealsoareslightlylargerthanthoseforoil.Thismaybeanotherreasonwhywater-basedsystemshavenotgainedwideacceptance.Originally,thelargersizeofcomponentsforwater-basedfluidcreatedahandicapwhendesigningsystems,andmorecostlyconstructioninflatedpricesofvalvesforwater-basedfluidtothreetimesormorethatofvalvesforoil.Now,however,valvesizesarecomparabletothoseforoil.ManyvalvesareavailablewithstandardNFPAfootprints.Thepricedifferentialhasalsobecomeless.Componentsforwater-basedfluidstillmaycostperhaps3%morethanthoseforoilsystems,butthismaybeabargainwhenyouconsiderthecost-savingpotentialofwater-basedsystems.$x9Y*b)K"pHFluidleakageLeakagecontinuestobeanaggingprobleminmanyhydraulicsystems.Newsealmaterialsanddesigns,andO-ringface-sealfittingsarepowerfulweaponsinthebattleagainstleakage.Butthebattleisfarfromoverbecauseofmisapplication,improperinstallation,orsimplelackofunderstanding.Althoughthere'snoexcuseforleakageinmostsystems,itstilloccurs.Assumingthatleakagewillnotbeeliminatedinthenearfuture,water-basedfluidcandramaticallyreducethecostsassociatedwithleakage.!Q:P/U(R4a:hInternalleakagecanbejustaswasteful.Thisleakagecancarburizetheoilbygeneratingheat.Internalleakagetypicallyisroutedbacktotank,sothistechniquetransformsmechanicalenergyintoheatinsteadofusefulwork.UsingastainlesssteelspoolwithPTFEsealsinavalveforwater-basedfluideliminatestheneedforclearancebetweenmovingcomponents.Becausethereisnoclearance,thereisnointernalleakage.,O,a;w,i4c;^4x7vButbeyondtheobviousandintangiblecostsoffluidleakage,disposingofthefluidthathasleakedfromasystembecomesaconcern.Allowinghydraulicoiltoenterplanteffluentsystemsbecomesanexpensivepropositionwhenremovalanddisposalcostsareconsidered.Realizingthatcleanupanddisposalcostswillonlygoup,andthatthepriceofoilisunstablesuggeststhatwater-basedhydraulicscanbeaneconomicalsolutiontoenvironmentalproblems.