工程機械攪拌設(shè)備用稱重傳感器的選型外文文獻翻譯、中英文翻譯、外文翻譯

MechanicalmixingequipmentworkswiththeselectionofloadcellThispaperengineeringmachinerymixingequipmentweighingsystemandthebasicrequirementsforspecialrequirements,proposedconstructionmachinerymixingequipmentweighingsystemusedtobeconsideredwhenthesensorseveralissues,thefocusofsensorprotectivestructureontheconstructionmachinerymixingequipmentreliabilityofoperation,pointingoutthatthecodegenerationIPTableprotectivelevelscannotcovermechanicalmixingequipmentworksfullprotectionofthesensorrequirements.Recommendationsdifferenttypesofmixingequipmentselectionofdifferentdefensivecapabilitiesofthesensor.WeighingSystemsensorsnormallyusedintheweighingsystemtoconsidertheamountoflimitedaccuracy,sensorinstallationspace,theenvironmentmayaffectthesensor,loadandthetypeofsensor,suchasthelifespanofvariousfactors.Engineeringmachinerymixingequipmentweighingsystemisnoexception.Theweighingsystemisdifferentbecauseofdifferentdemands,differentworkingconditions,tobeconsideredbyfocusingondifferentissuesonly.Engineeringmachinerymixingconcretemixingequipmentusuallyincludefloor(stations),theasphaltmixingplant,stabilizedsoilmixingconcretemixingplantsandshipsatsea,mixingthemwithconcretefloor(stations)themosttypical.Belowtheconcretemixingplant(stations)asanexampleforanalysis.1concretemixingplant(station)onthebasicrequirementsWeighingSystem1.1accurateweighingerroronthestrengthofconcreteisstronglyinfluenced,inparticularwater-cementratiomeasurementprecision,becausestrengthandwater-cementratioislinear.Therelevantnationalstandards,cement,water,additives,theadmixtureofdynamicmeasurementaccuracyof±1%,sand,stonedynamicmeasurementaccuracyof±2%.Quickmeetmixingstationdutycyclerequirements.varietythatmoneytothetypeofpre-selection,tofacilitatethetransformationtoadapttoavarietyofdifferentratioandcapacityrequirements.simplestructureweighingdevicestosimplestructure,solidandreliable,stableperformance,easyoperation.Clearly,theuseofelectronicweighingsystemsensormachineryweighingmorethanmeettherequirements.Therefore,theloadcellfloorintheconcretemixingstationstobemorewidelyused.However,objectivelyspeaking,comparedwiththemechanicalleverscalesinthe"solidandreliable,stableperformance,"asasensorelectronicweighingsystemhasmuchworktodo.2concretemixingstationsfloorintheloadcelloperatingconditionsForcommerceandthegeneralmeasurementofelectronicscalesagreatdifferenceis,inconcretemixingstationsfloorloadcellinaveryadverseoperatingconditions,stressenvironmentisverycomplex,andthegeneralelectronicproductscomparedtotheoperatingenvironment,agreaterrandomness.ambienttemperatureandhumidityConcretemixingstationisnormallyopenfloorinstallation,sensormaybesubjecttothesunandrain,temperaturedramaticchanges.Andmanyconstructionprojectsareinverybadnaturalconditionsinthemountainsorremoteareas.Therefore,wemustconsidergreatertemperaturerangeandhigherhumidityconditions.Concreteintheproductionprocessneedswater.Inthedeliveryofwaterandweighingprocessandalsohavealotofwaterinthegas,insomeformwithinrelativelysmallhumidenvironment.StirinthetemperaturecontrolintheHouse,therearehigh-temperatureandlow-temperatureconditionsofthedifferentrequirementsofcondition.Runninginthesummerwhenlow-temperatureconditiontothezero-belowcoldwindand力口冰stirring,thenbuildingacondensedwaterwillbewelldemonstratedhighhumiditybuilding.dustConcreteintheproductionprocessrequiresalargeamountofcement,coalashandtheappropriateamountofadmixture.Thesewereinthetransportationandpowderweighingprocesswillproducedust.Eventheaggregate,inthecourseoftransmissionhavealsodust.Someofthesedustsensorwillbeattachedtothesurface.Thedustandwatervaporinthecommonrole,thesensorwillbemoreseriouscorrosion.Therefore,thedamagepowderweighingsensorsusuallyweighthantheothersensorsmorefrequently.ShockandVibrationInthefeedprocess,theimpactofaggregatewillhave.Sensorsshouldbeabletobear5gacceleration.Stirintheprocess,willhavesustainedvibration,andvibrationwouldhavefatiguedamage.man-madeenvironmentMan-madeenvironmentistheproductreliabilitydesignoneofthefactorsthatmustbeconsidered.ConcreteMixingfloorinstalledattheconstructionsiteingeneral.Large-scaleuseoftemporaryworkersonsite,ofwhichaconsiderablenumberoftemporarylowlevelofeducation,lackofthenecessaryskills.Intermsoffacilities,suchasthemaintenanceandcleaningwork,thesensormaybeinthehigh-pressurewatersputtering,misoperationcausedoverload,andsoon.Clearly,thesensorshouldbeinsuchanenvironmentandalong-termreliableundertheconditionsoftheoperationistocarryoutsomespecialdesign.Thesebasicrequirementsandoperatingconditionscanbeusedasconcretemixingplant(stations)bytheloadcellselectionbasis.Threeconcretemixingplant(stations)tousewhenweighingsensortobeconsideredbytheSelectionProblems3.1weighingsensorpayloadcapacitydeterminationWeighingsensorpayloadcapacityusuallyHoppersensorratedload=+ratedthemselvesthatweight(0.6~0.7)xonlyafewsensorsInfactpeopleinthechoiceofsensorintegratedcapacityevenwhentheyconsiderthesizeandimpactloadselectedsafetyfactor.Safetyfactorwiththechoiceofsensorsensitivitycloselyrelated.Domesticandforeigncommonstrainloadsensorsensitivitymajorityof2mV/V,butthereare1mV/V,suchascolumnsensor;Also3mV/V,assomecantileversensorandsensorplateCentral;Twistedringsensorusually2.85mV/V.Stirupstairsintheuseofsensorsarebasically2mV/V.3.2weighingthechoiceofsensoraccuracyThechoiceofsensoraccuracyoftheweighingsystemtomeettheaccuracyrequirements,isnotone-sidedpursuitofthehighlevelsensoraccuracy.Inmulti-sensorcombinationusedonlywhenitsintegratederror△r=6/VnWhere,6onlyasinglesensoraccuracy,theuseofcombinationsofnisonlyafewsensors.CurrentlystirringupstairspopularS-typesensor,thecantileversensor,thesensorplatering,linear,hysteresis,repeatability,andtemperaturesensitivityeffectsofcreep,andotherkeyindicatorsvastmajorityofmanufacturersareisbetterthan0.05%,themajorityofmanufacturersbetterthan0.03%,somemanufacturersbetterthan0.02%.Itsintegratedsinglesensorerrorofclosetoorbetterthan0.1%.Multi-sensorcombinationonlyafteritsintegratederrorevensmaller.Itcanbesaidthatthegeneralloadcellmanufacturersofproductstomeettherequirements.Previously,manymanufacturersstirringfloor,itsprovisionsstaticaccuracyoftheweighingsystem,respectively0.1%and0.3%respectively.Thus,theuseofsingle-sensorweighingonly,individualindicatorsof0.05%ofthesensorwillsatisfy0.3%precisionweighingrequirements.Theuseofthreeovertheweigh-sensor,singleindicators0.05%sensorscanalsomeet0.1%accuracyrequirements.Itmustbepointedoutisthattheaccuracyoftheweighingsystemisstaticprecision,whiletheconcreteisthenationalstandardsrequiredynamicaccuracy,whichisduetotheconstantweighingofrawmaterialsforthematerialinthebodyofgravityweighingtheimpactoferrorsincreasedsignificantly.Above0.1%and0.3%respectively,theabilityofstaticaccuracyreached1%and2%ofthedynamicaccuracyforfeedingsystemwiththedesign.Now,manymanufacturersprovisionsoftheaccuracyofitsweighingsysteminthe0-ratedweighingthatmoneywithinthecement,water,additives±1%,sand,stone±2%.Notes,ready-mixedconcretenationalstandardsrequirethatphysicalmeasurementaccuracy,andgeneralmeasurementinstruments0~20%oftherelativeerrorgreater,orconcretemixingplant(station)providestheindustrystandardinthe20~100%oftheweightingofthemeetcement,water,additives±1%,sand,stone±2%ofthemorepracticalmeasurestoallowsomedeviation.Amorereasonableapproachistheuseofprecisionweighinginstrumenttaggingindustryterminologytoexpressthatasacumulativehopperscalesshouldbeusedinautomaticweighingaccuracyofthegradingmarks1.0and2.0.Suchscaletestprojectinlinewiththepurposes,includingbothmaterialstesting(determiningtheaccumulatederror)alsoincludesstatictest.AutomaticWeighingatitsmaximumallowableerrorinTable1.Criteriausedinastaticloadtestandnon-automaticweighing,shouldmeettherequirementsinTable2.Usually1.0weighdesignforthe1000points,2.0Balanceofdesignfor500points.Wecanseethattherangeinthehigh-1.0scaleerroris0.15%,2.0Balanceoferroris0.3%,notmanufacturersthanbeforeprovisionsof0.1%and0.3%statichighaccuracy.Butinthelowrangeofaccuracyisindeedincreased.Undersuchcircumstancestheneedtoconfirmtheselectioninthelowrangeofthesensorcanalsomeettherequirements.Accordingtoweighthedegreeofchoiceofthesimplestsensoris1,000pointsmethodofselectionof1000attheweigh-insensors,500hoursoftheweigh-selection500pointsofthesensors.Nationalstandardsinweighingsensoraccuracyistousethedegreetoexpress,butbecauseofvariousreasons,mostproductionplantsthatstillusesingleindicatorsensoraccuracy.Accordingtoindividualuserstocalculateindicatorsintegratedprecisionerror.Chooseuptroublepoint.Theconcretemixingofforeigndevelopedcountriesfloorgeneralwithprecisionweighingsystemtothedegreethat,inthe1000Indexing.Theymayberelatedtotheuseofhigh-performanceconcretehighproportionofthe.Astheeconomyandthecontinuousdevelopmentoftechnology,ultra-high-risebuilding,longbridges,large-scalewaterconservancyprojects,aswellasotherexposedtotheharshenvironmentintheconstructionofconcreteperformanceraisedhigherandhigherdemands,concretetechnologyhasalsoenteredthehigh-techage,theproportionofhigh-performanceconcretecontinuousimprovement.Inadditiontoproducinghigh-performanceconcretecorrectselectionofrawmaterials,determineareasonableprocessparameters,theconstructiontechnologyofcontrolisalsoveryimportant.Stiringredientsintheconcretefloor,theaccuracyofthesystemisimportant.3.3sensorstructureformsofchoiceCommonlyusedapull-typeS-shapedsensors,theplatecenterringandringcruciatetendons,suchasplate.Crosscenterringreinforcementplatehighaccuracysensors,anti-partialcontainsexcellentperformance,buthigherpricesarenormallyonlyusedinhigh-precisionmeasurementoccasions.MixingupstairsiscommonlyusedS-typesensorsandsensorplateCentral.S-typesensorwhichitshighaccuracy,anti-partial-carryingcapacity,atthesametimecanbringoverloadprotection,thewiderangeofuseoftheadvantagesofthelargest.Popularpressuresensorofacantileverbeam,Spoke,column,bridge,suchasring-twisting.Consideredaccuracy,rangeofinstallation,priceandotherfactors,thevastmajorityofproductionplantstochoosestirringfloorofthecantilever.3.4loadtypeofconsiderationConcreteproductionmainlyusessand,gravel,cementandwater,additives,admixture.Severalmaterialsweightheimpactofafewstoneasthegreatest.Inthelargefamilyofelectronicscales,suchisnotthegreatestimpact,thesensorcangenerallybearoverloadsituation.Fromtheauthorofthesurvey,thesensoroverloadanddamageduetothesituationfromtimetotime.Forexample,acontrolsystemfault,causingheavymaterialdisposalandthenext,causingoverload.Alsotheuseofhumanfactorsduringtheoverload,especiallythesmallrangesensorfortheoperatorstampedeScaleFrameandoverloaddamagethingshappenfromtimetotime.Thereforesensor,sensorswhetherWeighingSystemOverloadProtectionforthereliableoperationofacertaininfluence.Sensorperformanceindicatorshavetwowiththis,firstallowingoverload,firstlimitoverload.Allowoverloadreferstoshedtheload,sensorperformanceindicatorsunchanged.Limitoverloadreferstotheloadsensordoesnotproduceharmfulpermanentmechanicaldeformation.Generaloverloadsensorallowsfor150%,andoverloadlimitin200%~300%.Someofthesensorwithoverloadprotectionarelikelytoexceedthescopeofone.SensorssuchasPutianfactoryCFCKN-1-becauseoftheirspecialsensordesign,allowingtheloadashighas500%.Suchfrequentoverloadsensorinthecasecanreliablywork.3.5sensorprotectionratingSensorIPprotectionlevelsthatareusuallyused.GeneralsensormanufacturerssaidtheirproductshavereachedIP67level,asmallnumberofmanufacturersofsomeproductstoIP68level.WeknowthattheIPcodeisexpressedbynotmorethan72.5kVvoltageelectricalproductsprotectiveshellofgrading.Nationalstandards"GB4208-93shellprotectionlevels",IP67meanstheproductcandust,andagainstshort-termimmersion;IP68meanstheproductcandust,andagainstcontinueddivingimpact.Itmustbepointedoutisthatsuchprotectiondoesnotincludemechanicaldamage,corrosion,orexternalinfluencessuchashumidenvironmentalconditions.Usuallyinvolvingsuchprotectionprovidedbytherelevantproductstandards.Weighingsensorsandgeneralelectricalproductsandsecondaryproductsofdifferentinstruments,itisalsoaforcecomponentintheoperationofconstantlybeingproducedandtheroleofdeformation.Thereisalsolikelytobeshock,impactorimpactsuchamechanicaldamage,dustandwatervaportothemorecommonunderseverecorrosionandinextremelyhumidconditionsrunning.ThisisGB4208-93underthetestconditionsarequitedifferent.Haveencounteredsuchasituation:aweigh-oreminesonselectedimportssensor,alargesteelladleweighontheselectionofaninternationallyrenownedbrandssensors,arewelded,sealedandverybeautiful,toIP68level.Butinactuallifeveryshortscene.Inthelastresortcircumstances,thetrialofPutiansensorplantproducts.Theaccidentcameastheresultoftheirservicelifeinexcessofimportssensor.Oneinalargesteelladleweighonthesensorhasbeeninoperationforsevenyears,arestillrunning.Inthesetwoexamples,thefactistheprotectionofdistinction.First,therewerestillnoshellcasing;Second,welddesign.Third,sealingmaterials.Generallyspeaking,thedesignisbetterthannoshellcasingdesign;Thedesignoftheweldseamshouldbeavoidedasfaraspossiblebyforce.Intheunavoidablecircumstances,willhavetocheckweldstrength,inparticularthefatiguestrength.Fatiguecracksarecausedminortidalleadentry,theimportantreasonsforsensorfailure.Theaforementionedweldingofaworld-renownedbrandsensoratthescenesealedthereasonsfortheshortlifeofexcessiverelianceontheweldingissealed,theinternalstraintabletsonlyathinplasticseallevel,onceweldcracks,moisturesensorontheroleintherapidfailure.Insealingmaterialsneedtoberemindedthat,throughIP67half-hoursoakingtestsensorsmaynotbeabletoknow,sensor-standarddampheatinthe12-cycletest.Subjecttotheimpactofpricecompetition,manycanceledsensorplantprotectionframes,pull-typesensorisevenworse.ThecurrentdomesticproductionofS-typesensor,thesensorplateCentralalmostcanceledshell.Indeed,onmanyoccasionsthereisnothingwrongwithdoingso.However,insuchaconcretemixingplantenvironmentalconditions,maynotbethebestchoice.IplantforthedesignoftheThreeGorgesProjectmixingplantproductionCFCKN-1Caseclosureweldingsensorservicelifeupto10years.WehaveseentheUnitedStatesandJapanupstairsEuropeconcretemixingwiththepull-typesensoriswiththeprotectionofthemajorityoftheshell.Theythinkthatshouldbeasemi-permanentsensordevices,lifeshouldnotbelessthan106times.Yearsofpracticehasprovedthat,CFCKN-1-S-typesensorandsensorordinarycomparedtoaminimumthefollowingadvantages:shellthickness,andagainstmechanicaldamage,inparticularthestronganti-collisionoutside;welddepth,corrosionresistancetowearalongtime;overloadprotectiongapiswithintheshell,donotdustordebrisaccumulatedbyblocking;Weighingsensordesignisareasonableshellweighingdevice"solidandreliable,stableperformance,"animportantguaranteeforselection,mustbeseriouslyconsidered.360differenttypesofmixingtheselectionofloadcellbreakdownLargeandmedium-sizedwaterconservancyprojectsofconcretemixingplant,urbancommercialconcretemixingplant,smallirrigationworksandhighwayconstructioninthecountyusedintheconcretemixingplantsizespecifications,theuseofcontinuous-time,theinstallationlocationsenvironmentalconditionsareverydifferentfromtheproductionofconcreteperformancerequirementsareverydifferent.Therefore,thereliabilityofthesensor,theprotectivepropertiesingradesalsohavedifferentrequirements,shouldbetreateddifferently.Longhoursofcontinuousoperation,harshenvironmentalconditionsandtheproductionofhigh-performanceconcretemixingplantshouldchoosereliability,ahighlevelofprotectionsensors.Theremainingrequirementscanbeappropriatelyreduced.Forrunningontheconcretemixingvesselatsea,itisalsonecessarytoconsidertherequestofanti-saltspray,notindividuallyelaboratehereonthe.工程機械攪拌設(shè)備用稱重傳感器的選型本文闡述了工程機械攪拌設(shè)備稱重系統(tǒng)的基本要求和特殊要求，提出了工程機械攪拌設(shè)備稱重系統(tǒng)選用傳感器時需要考慮的幾個問題，重點分析了傳感器防護結(jié)構(gòu)對工程機械攪拌設(shè)備運行可靠性的影響，指出IP代碼所代表的防護等級不能涵蓋工程機械攪拌設(shè)備對傳感器的全部防護要求。建議不同類型的攪拌設(shè)備選用不同防護能力的傳感器。稱重系統(tǒng)中選用傳感器通常要考慮稱重系統(tǒng)的量限、準(zhǔn)確度、傳感器的安裝空間、周圍環(huán)境對傳感器的可能影響、加載的類型以及傳感器的壽命等諸方面因素。工程機械攪拌設(shè)備的稱重系統(tǒng)也不例外。只是不同的稱重系統(tǒng)由于要求不同，工作條件不同，所要考慮的問題側(cè)重點有所不同罷了。工程機械攪拌設(shè)備通常包括混凝土攪拌樓（站）、瀝青攪拌站、穩(wěn)定土拌和廠以及海上混凝土攪拌船等，其中以混凝土攪拌樓（站）最為典型。下面就以混凝土攪拌樓（站）為例進行分析?；炷翑嚢铇牵ㄕ荆ΨQ重系統(tǒng)的基本要求準(zhǔn)確稱量誤差對混凝土的強度影響很大，特別是水灰比計量精度，因為強度和水灰比是線性關(guān)系。相關(guān)國家標(biāo)準(zhǔn)規(guī)定，水泥、水、外加劑、摻合料的動態(tài)計量精度為±1%，砂、石料的動態(tài)計量精度為±2%?？焖贊M足攪拌樓站工作循環(huán)的要求。種類多稱量值預(yù)選的種類要多，變換要方便，以適應(yīng)多種配比和不同容量的要求。結(jié)構(gòu)簡單稱量裝置要結(jié)構(gòu)簡單，牢固可靠，性能穩(wěn)定，操作容易。顯然，采用傳感器電子稱重系統(tǒng)較之機械秤更能滿足要求。因此，稱重傳感器在混凝土攪拌樓站中得到了越來越廣泛的應(yīng)用。但是，客觀地說，與機械杠桿秤相比，在“牢固可靠，性能穩(wěn)定”方面，傳感器電子稱重系統(tǒng)還有很多工作要做?；炷翑嚢铇钦局蟹Q重傳感器的運行條件與一般用于商貿(mào)計量的電子秤的一個很大的不同之處在于，混凝土攪拌樓站中稱重傳感器處于相當(dāng)惡劣的運行條件中，應(yīng)力環(huán)境十分復(fù)雜，與一般的電子產(chǎn)品的運行環(huán)境相比，有更大的隨機性。環(huán)境溫度和濕度混凝土攪拌樓站通常是露天安裝，傳感器可能遭受日曬雨淋，溫度劇烈變化。而不少工程建設(shè)項目是在自然條件相當(dāng)惡劣的山區(qū)或邊遠地區(qū)。所以，必須考慮更大的溫度范圍，更高的濕度條件?；炷猎谏a(chǎn)過程中需要水。在水的輸送和稱量過程中也會產(chǎn)生不少水氣，在一定的小范圍內(nèi)形成較為潮濕的環(huán)境。在溫控攪拌樓中，則有高溫工況和低溫工況的不同要求。夏天運行在低溫工況時要通入零度以下的冷風(fēng)以及加冰攪拌，這時樓內(nèi)會出現(xiàn)冷凝水，足見樓內(nèi)濕度之高。粉塵混凝土在生產(chǎn)過程中需要大量的水泥、煤粉灰以及適量的外加劑。這些粉狀物在輸送和稱量過程中會產(chǎn)生粉塵。即使是骨料，在輸送過程中也有粉塵產(chǎn)生。這些粉塵有一部分會附著在傳感器表面。在粉塵和水氣的共同作用下，傳感器將受到較為嚴重的腐蝕。所以，粉料秤傳感器的損壞通常要比其他秤的傳感器更頻繁一些。沖擊與振動在進料過程中，砂石料會產(chǎn)生沖擊。傳感器應(yīng)能承受5g的加速度。在攪拌過程中，會產(chǎn)生持續(xù)的振動，而振動會產(chǎn)生疲勞破壞。人為環(huán)境人為環(huán)境是產(chǎn)品可靠性設(shè)計時必須考慮的因素之一。混凝土攪拌樓一般安裝在施工現(xiàn)場。工地上大量使用臨時工，其中相當(dāng)多的臨時工文化水平較低，缺少必要的技能。在設(shè)備的維修和清洗等工作中，很有可能發(fā)生傳感器受到高壓水的濺射，誤操作引起過載等情況。顯然，傳感器要在這樣的環(huán)境條件下長期可靠的運行，是要進行一些特殊設(shè)計的。上述基本要求和運行條件可以作為混凝土攪拌樓（站）用稱重傳感器的選型的依據(jù)?；炷翑嚢铇牵ㄕ荆┯梅Q重傳感器選型時需要考慮的幾個問題稱重傳感器載荷容量的確定稱重傳感器載荷容量通常按下式計算傳感器額定載荷=料斗自重＋額定稱重量（0.6~0.7）x傳感器只數(shù)事實上人們在選擇傳感器容量時往往還要綜合考慮沖擊載荷的大小以及選定安全系數(shù).安全系數(shù)的選擇又與傳感器的靈敏度有密切關(guān)系．國內(nèi)外常見的應(yīng)變式稱重傳感器靈敏度多數(shù)為2mV/V,但是也有1mV/V的，如柱式傳感器；也有3mV/V的，如部分懸臂梁式傳感器和板環(huán)式傳感器；扭環(huán)式傳感器則通常是2.85mV/V。目前在攪拌樓上使用的傳感器基本上都是2mV/V的。稱重傳感器準(zhǔn)確度的選擇傳感器準(zhǔn)確度的選擇以滿足稱量系統(tǒng)的準(zhǔn)確度要求為準(zhǔn)，不必片面追求過高的傳感器準(zhǔn)確度等級。在多只傳感器組合使用時，其綜合誤差按下式計算6r=6/Yn式中，6為單只傳感器的準(zhǔn)確度，n為組合使用的傳感器只數(shù)。目前攪拌樓上常用的S型傳感器、懸臂梁式傳感器、板環(huán)式傳感器，其線性、滯后、重復(fù)性、靈敏度溫度影響、蠕變等主要指標(biāo)絕大多數(shù)廠家均優(yōu)于0.05%，大多數(shù)廠家優(yōu)于0.03%，部分廠家優(yōu)于0.02%。其單只傳感器的綜合誤差都接近或優(yōu)于0.1%。多只傳感器組合后其綜合誤差就更小了?？梢哉f一般稱重傳感器生產(chǎn)廠家的產(chǎn)品都能滿足要求。以前，不少攪拌樓生產(chǎn)廠家規(guī)定其稱重系統(tǒng)的靜態(tài)精度分別為0.1%和0.3%。這樣，對于使用單只傳感器的秤而言，單項指標(biāo)為0.05%的傳感器就可以滿足0.3%精度的秤的要求。對于使用三只以上傳感器的秤而言，單項指標(biāo)0.05%的傳感器也能滿足0.1%精度的要求。需要指出的是，上述精度是稱重系統(tǒng)的靜態(tài)精度，而混凝土國家標(biāo)準(zhǔn)要求的是動態(tài)精度，這是由于原材料不斷地向稱量機構(gòu)供料在重力的沖擊下稱量誤差明顯增加。上述0.1%和0.3%的靜態(tài)精度能否保證分別達到1%和2%的動態(tài)精度還與供料系統(tǒng)的設(shè)計有關(guān)?，F(xiàn)在，不少廠家規(guī)定其稱重系統(tǒng)的精度在0~額定稱量值的整個稱量范圍內(nèi)為水泥、水、外加劑±1%，砂、石料±2%。須知，預(yù)拌混凝土國家標(biāo)準(zhǔn)要求的是實物計量精度，而一般計量儀器在0~20%范圍相對誤差較大，因此，還是混凝土攪拌樓（站）的行業(yè)標(biāo)準(zhǔn)中規(guī)定的20~100%的稱量段滿足水泥、水、外加劑±1%，砂、石料±2%的計量允許偏差更為實際一些。更為合理的精度標(biāo)注方式是采用衡器行業(yè)的術(shù)語來表述，即作為累計料斗秤，應(yīng)采用自動稱量準(zhǔn)確度的等級標(biāo)志1.0和2.0。這類秤的檢定項目與用途相適應(yīng)，既包括物料試驗（確定累計誤差）也包括靜態(tài)檢定。其自動稱量時的最大允許誤差見表一。在用標(biāo)準(zhǔn)載荷進行靜態(tài)檢定和進行非自動稱量時，應(yīng)滿足表二的規(guī)定。通常將1.0級秤設(shè)計為1000分度，2.0級秤設(shè)計為500分度?？梢钥闯?，在高量程端1.0級秤的誤差為0.15%，2.0級秤的誤差為0.3%，并不比以前廠家規(guī)定的0.1%和0.3%靜態(tài)精度高。但是在低量程段精度要求確實是提高了。在這種情況下需要確認所選用的傳感器在低量程段能否也滿足要求。按秤的分度數(shù)選擇傳感器最簡單的方法就是1000分度的秤選用1000分度的傳感器，500分度的秤選用500分度的傳感器。稱重傳感器國家標(biāo)準(zhǔn)中準(zhǔn)確度就是用分度數(shù)來表示的，但是由于多方面的原因，目前大多數(shù)生產(chǎn)廠仍用單項指標(biāo)表示傳感器的精度。用戶再根據(jù)單項精度指標(biāo)算出綜合誤差。選用起來麻煩一點。國外發(fā)達國家的混凝土攪拌樓稱重系統(tǒng)精度一般用分度數(shù)來表示，規(guī)定為1000分度?？赡芘c他們使用高性能混凝土所占比例高有關(guān)。隨著經(jīng)濟和技術(shù)的不斷發(fā)展，超高層建筑、超長橋梁、大型水利工程以及其他暴露在嚴酷環(huán)境中的建筑對混凝土的性能提出了越來越高的要求，混凝土技術(shù)也進入了高科技時代，高性能混凝土的應(yīng)用比例不斷提升。生產(chǎn)高性能混凝土除了要正確選用原材料、確定合理的工藝參數(shù)外，施工工藝的控制也是十分重要的?；炷翑嚢铇侵信淞舷到y(tǒng)的準(zhǔn)確度是其中重要的一環(huán)。傳感器結(jié)構(gòu)形式的選擇常用的拉式傳感器有S形，板環(huán)式以及中心十字筋板環(huán)式等。中心十字筋板環(huán)式傳感器精度