全文预览已结束
下载本文档
版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
TheFeaturesandDevelopmentHistoryandApplicationofHydraulicandPneumaticTransmutation1.Theadvantagesofhydraulictransmission1)Ahydraulicsystemcanproducehigherpowerthanelectricalequipmentunderthesamevolume.Thehydraulicequipmentsystemhassmallervolume,light,highpowerconsistencyandcompactconfigurationatagivenpower.Thevolumeandweightofahydraulicmotorareabout12%ofanelectricmotor.2)Hydraulicequipmenthasagoodworkingstability.Itisbecauseoflight,lessinertia,quickresponse:thehydraulicequipmentcanrealizeceleritystart-up,brakeandfrequentchangeinmotiondirection.3)Thehydraulictransmissioncanreachawiderangeofspeedregulation(withtherangeof1:2000),andthespeedcanalsoberegulatedduringtheworkprocessing.4)Thehydraulictransmissioncaneasilyrealizeautomationandthepressure,flowrateandtheflowdirectioncanberegulatedandcontrolled.Ifwecombineitwithelectric,electronorpneumaticcontrolsystems,amorecomplextransmissionsystemwithremotecontrolcanberealized.5)Thehydraulicsystemcanprotectfromover-loadeasily,whichcannotbedonebyelectricityormachineequipment.6)Becauseofstandardization,series,andall-purposeapplication;thehydraulicsystemiseasierindesign,fabricationandapplication.7)Thehydraulicsystemiseasierthanmachineequipmentindoinglinemotion.2.Theshortagesofhydraulictransmission1)Leak.Oilleaksareinevitablebecauseofthelossinfluidflowresistance.Somoreenergylossexistsinahydraulictransmission.2)Workingtemperature.Theworkingtemperaturehasstrongeffectontheworkingpropertyofahydraulicsystembecauseoftheviscosity-temperaturecharacterofhydraulicoil.Itissuitableforworkinginapropertemperature.3)Cost.Thecostishighbecauseoftheneedsinhighprecisionfabricateforhydraulicelements.4)Itisdifficulttofindthereasonsoffault.3.Theadvantagesofpneumatictransmission1)Theaircanbeobtainedandexpelledfromtheatmosphere.Itcannotbringpollutiontotheenvironment.2)Itisoflowviscosityandlowerpressurelossinpipes.Thepressureairisconvenientforconvergencesupplyandremotetransportation.3)Itisoflowworkingpressure(usually0.3-0.8MPa).Avowersmaterialandfabricateprecisionisrequiredforthepneumatictransmissionelements.4)Thepneumatictransmissionhasasimpleservicing.Theairpipeisnoteasytobejammed.5)Safety.Thepneumaticsystemcanprotectfromover-loadeasily.4.Theshortcomesofpneumatictransmission1)Itisbecauseofaircompressibility.Theworkingstabilitiesforpneumatictransmissionsystemarepoorerthanthoseofhydraulictransmissionsystem.2)Becauseoflowerworkingpressureandsmallsizeinconfiguration,thepushforceofpneumatictransmissionisusuallyverylower.3)Lowertransmissionefficiency.Tosumup,thestrong-pointsofhydraulicandpneumatictransmissionhavetakenthemainadvantages,andtheshortageshavebeenovercomeandimprovedbytechnicalrenovation.ThefundamentallawunderlyingthewholescienceofhydraulicswasdiscoveredbyBlasiePascal,aFrenchphysicist,intheseventeenthcentury.Butitwasnotuntiltheendofthe18centurythatmanfoundwaystomakethesnuglyfittingpartsrequiredinhydraulicsystemsandothermodernequipment.Sincethenprogresshasbeenrapid.Hydraulictransmissionhasbeenexperiencingtheprocessasbelow.The17thand18thcenturieswereaproductiveperiodinthedevelopmentofhydraulictheory.Torricellistudiedfluidmotionintheearly17thcentury.Lateinthatcentury,SirIsaacNewtonconductedstudiesonviscosityandtheresistanceofsubmergedbodiesinamovingfluid.Thekeyachievementsoftheperiodoccurredinthemiddleofthe18thcenturywhenDanielBulliondevelopedthetheoryoftransmissionofenergyinfluidstreamsandBlasPascal,ataboutthesametime,establishedtheprincipleofhydrostaticpressuretransmission.Thisprinciplewasfirstusedinthelatterpartofthe18thcentury.ThefirsthydraulicpressuremachinewasmanufacturedbyEnglandinthelate18thcentury.ThefundamentalsoffluidtheorywereestablishedbytheaboveworkandrefinementswereaddedbyNavierwhoderivedthemathematicsofmotioninliquidsincludingequationsforfluidflowwithfriction.Thiswasearlyinthe19thcentury.ItwasfollowedbytheworkofStokes,whoindependentlydiscoveredthesameequationsandfurtherextendedtheworkofNavicert.Recentlyhydraulicandpneumaticpressuretransmissiontechnologyhasbeendevelopedwithalargescalepetrolicindustryinthe19thcentury,andthebarbettedisplacewasthefirstonesuccessfulusinghydraulicequipment,andthenhydraulicmachinetool.InWorldWarImanynewmachinesbasedontheprinciplesofhydraulicshadbeenused.Thegreatautomotiveindustyintroducedhydraulicbrakesintheearlythirtiesandhydraulictransmissionsinthelatethirties.Thetractorindustrybeganusinghydraulicsin1940toincreasetheflexibilityandutilityoffarmequipment.InWorldWarIIbecauseofthedemandtransmissionandcontrolequipmentsinfastreaction,precisionactionandhighoutputpowersboosteddevelopmentinhydraulictheology.AftertheWar,thehydraulicdevelopmentturnedintocivilindustry,suchasmachinetool,engineering,metallurgy,plasticmachine,farmmachine,vehicleandwatercraft.Inmorerecentyears,theroleofleadershipinhydraulicpowerapplicationhasbeentakenoverlargelybysomeofthelargeearthmovingandconstructionequipmentmanufacturers.Thetotalpowerinvolvedisoftengreaterthanthatrequiredineventhelargestaircraftsystems.Withthedevelopmentofhigherautomationofhydraulicmachinesandincreasinguseofhydraulicandpneumaticelements,thescaledelementsandintegratedhydraulicsystemwithminiaturizationisinevitable.Especiallyinrecentyearshydraulicandpneumatictransmissioniscombinedcloselywiththesensorandmicro-electricitytechnology.Ithasbeenemergingamountsofnewvalvessuchashydraulic-electricityproportionalvalves,digitalvalves,hydraulicandelectro-hydraulicservocylindersandtheintegrativeelements,whichwillleadthehydraulicandpneumatictechnologytothedevelopmentofhigherpressure,higherspeed,largerpower,lowerenergywastageandnoise,longevityandhighintegration.Computeraideddesign(CAD)andtest(CAT)andpracticalcontroltechnologyusedinhydraulicandpneumaticsystemwillbethetrend.Nowadaystheapplicationofhydraulictransmissionsystemhasbecomeoneoftheimportantindicationsofindustrylevelforacountry.Indevelopedcountries,95%ofengineeringmachine,90%ofnumericalcontrolcenterandmorethan95%ofautomationassemblylinesusethehydraulictransmissionsystem.液压与气压传动的特点及发展应用概况1.液压传动有以下优点1)在同等体积下,液压装置毕电气装置产生更高的动力。再同等功率下,液压装置体积小,重量轻,功率密度大,结构紧凑。液压马达的体积和重量只有同等功率电动机的12%左右。2)液压装置工作比较平稳。由于重量轻、惯性小、反应快,液压装置易于实现快速启动、制动和频繁的换向。3)液压装置能在大
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 2024年计算机维修项目资金申请报告代可行性研究报告
- 四年级下册语文试题-第四单元主题阅读(含答案)部编版
- 《祝福》课件+2023-2024学年统编版高中语文必修下册
- 企业工作总结及信息技术
- 医院治疗工作总结
- 企业员工离职风险分析总结
- 消防队伍队员岗前培训总结
- 企业年度工作总结及环保管理
- 《延续文化血脉》守望精神家园
- 公司部门工作总结
- 员工外派协议书
- 蒸发器安全操作规程
- 父母子女间借款协议
- 小学一年级《拼音直呼练习》
- 原始股权协议(推荐5篇)
- 生物基高分子材料
- 线控制动系统
- 小学美术-民间玩具教学设计学情分析教材分析课后反思
- 《二手车评估与鉴定》课题四 二手车价值评估
- 人教版三年级下册八数学广角搭配说课一等奖
- 普宁2023年中学教师招聘考试真题及答案解析
评论
0/150
提交评论