Въведение
Intheearlynineteenthcentury,theleadtypeproductiontechnologywasintroducedtoChinafromtheWest.Inthesubsequentdevelopment,theproductionofcoppermoldshaschangedwitheachpassingday,andtheleadtypecastinghasalsoimproved.Anddevelopfrommanualoperationtomechanization.Atfirst,hand-pattedtypecastingfurnaceswereusedforcastingtype.Later,foot-operatedtypecastingfurnacesandhand-operatedtypecastingfurnaceswereused,andthespeedincreasedto700to800charactersperhour.IntheearlyyearsoftheRepublicofChina,theCommercialPressintroducedthe"ThomsonAutomaticCastingFurnace".Notonlyhasmorethan15,000charactersbeencastdaily,butthecastedcharacterscanbeuseddirectlywithoutprocessing.Sofar,thecastingtechnologyhasreachedmaturity.
Сурови материали
Оловото е синьо, сребристо-бял тежък метал. Токсичен е и е група метали с разтегливост. Точката на топене е 327,502°C, точката на кипене е 1740°C, плътността е 11,3437 g/cm^3, твърдостта е 1,5, текстурата е мека и якостта на опън е малка.
Leadisoneoftheearliestmetalsusedbyhumans.In3000BC,humansalreadysmeltedleadfromore.Thecontentofleadintheearth'scrustis0.0016%,andthemainoreisgalena.Thereare4stableisotopesofleadinnature:lead204,206,207,208,andmorethan20radioactiveisotopes.
Metalleadisaffectedbyoxygen,waterandcarbondioxideintheair,anditssurfacewillquicklyoxidizetoformaprotectivefilm;underheating,leadcanquicklycombinewithoxygen,sulfur,andhalogen;leadandcoldhydrochloricacid,Coldsulfuricacidhasalmostnoeffectandcanreactwithhotorconcentratedhydrochloricacidandsulfuricacid;leadreactswithdilutenitricacid,butdoesnotreactwithconcentratednitricacid;leadcanslowlydissolveinstrongalkalinesolutions.
Leadismainlyusedtomakeleadstoragebatteries;leadalloyscanbeusedforleadcastingandsoldering;leadisalsousedtomakeprotectiveequipmentforradioactiveradiationandX-rays;leadanditscompoundsaremoretoxictothehumanbody.Andcanaccumulateinthehumanbody.Leadisusedasabuildingmaterial,usedinleadacetatebatteries,usedasbulletsandshells,solder,trophies,andsomealloysalsocontainlead.
Светлинен профил
Thelightingprofileisanindispensablelightingpropduringtheshootingprocess(especiallyindoorshooting).
Thisitemiscomposedofmanysmallsquares,andthesizecanbechangedaccordingtothesituation.Itcanmakethestronglightbecomesoftlight(withoutobviouscontour)afterbeingreflected,andithasnoeffectontheactorsandthelens.
Копиране
Aprintingplatemadeofpaper-castingcliche,usuallycalleda"copyversion".Theproductionprocessofthecopyplateistofirstarrangethemovabletypeplateexactlyasrequiredbytheleadtypeprintingplate,andthenusethemovabletypeplateasthemastertopressitintoanengravedtypecalledmudtypeandpapertypewithmudorspecialthickpaper,andthenusethemudTypeorpapertypecaststhecliche,andfinallyusesthecliche(fullpage)asaprintingplatemountingmachineforprinting.Theinventionandapplicationofthisprocesstechnologymarkedthedevelopmentofmodernletterpressprintingtoanewstage.
PapertypewasinventedbytheFrenchmanXieLuoin1829.By1871,AmericanB.B.Blackwellinventedtheuseofthinclicheplates,whichwereprintedonawoodenbackground.Theinventionandapplicationofpapertypemadetheletterpressprintingtechnologymature.Atthattime,asetofpapermoldscouldbecastmorethantentimes.Inthisway,aftertheleadtypeplateisarranged,onceitistypedintoapapertype,theplatecanbedisassembledtoreturnthetype,andthepapertypeisretainedforlateruse.Thepapertypeisnotonlyconvenientforstorage,butalsobecauseofitslightness,itcanbetransportedtoremoteplacesandprintedinmanyplaces.Ithascreatedfavorableconditionsfortheprintinganddistributionofbooksandperiodicals,especiallynewspapers.
Процес на леене
Thecastingprocessisamethodofmassproductionofjewelrywithacastingmachine.Thismethodhastheadvantagesofimprovingworkefficiencyandreducingcost.Theprocessingprocedureisasfollows:
Therubbermoldismadeaccordingtothejewelrydesignsample;therubbermoldisusedtomakeawaxmoldbywaxinjection;thewaxmoldisplantedintoawaxtree;thecylinderwiththewaxtreeispouredintoplastertomakePutthegypsummoldintotheovenfordrying,andheatituntilthegypsummoldisdewaxed;pourthemoltengoldintothegypsummold;cleanandremovethegypsum,thenperformpolishingandinlayingprocedures.
Опасности от олово
Хронична токсичност
Long-termexposuretoleadanditscompoundscancauseheartpalpitations,excitement,andincreasedbloodredbloodcells.Afterleadinvadedthenervoussystem,insomnia,dreaminess,memoryloss,fatigue,andthendevelopedintomania,blindness,confusion,coma,andfinallydiedduetocerebrovascularhypoxia.Thebloodleadlevelisoftenhigherthan2.16micromol/Lbeforeclinicalsymptomsappear.Therefore,althoughthebloodleadlevelinmanychildrenishigh,thereisnospecialdiscomfort.Mildintellectualorbehavioralchangesarealsodifficulttobeaffectedbytheparents.Orthedoctorfoundout.Thisiswhytheleadpoisoningofchildreniscalled"hiddenkiller"abroad.
Канцерогенен
Animalexperimentsonleadinorganiccompoundshaveshownthattheymaycausecancer.Accordingtoliteraturerecords,leadisachronicandcumulativepoison,anddifferentindividualshaveverydifferentsensitivities.Forhumans,leadisapotentialurinarysystemcarcinogen.
Teratogenicity:Therearenotenoughanimalteststoprovideevidencethatleadanditscompoundsareteratogenic.
Mutation:Feedingmicewith1%leadacetatefeedincreasesthenumberofchromosomalfissure-fractureaberrationsinleukocyteculture.Thesechangesinvolveasinglechromosome,indicatingthatDNAreplicationisdamaged.
Процес на изработка на плочи
Usingmovabletypeastheoriginalplateandcopyingitintoastereotypecannotonlyimprovetheprintingenduranceoftheprintingplate,butalsocanbeusedforprintingindifferentplacesoronmultipleprintingpresses.
Типографията се нарича още типография на хартия, а процесът на изработка на табели:
Оригинал→Производство на хартия→Отливане типография→Ревизия→Покритие
Тип за производство на хартия
Papertypeistocoverspecialpapertypepaperonmovabletypeorcopper-zincplate,applypressuretomakeatemplateforcastingleadplate.Thepapermoldcanbecastintoaflatandarc-shapedleadalloyprintforprintingonaflatbedmachineorarotarymachine.Thepapertypeiseasytosendtootherplacesforcastingandprinting,anditcanbestoredforalongtimeforreprinting.
Therearetwocommonlyusedmethodsforpapermaking,oneiswetmakingandtheotherisdrypressing.
(1)Thewetprocessistoplacetheoriginalplateintheironframeontheirontable,configureproperironbarstofastenit,brushawaythedust,andplacethepaper-shapedmaterialontheoriginalplateformolding.Whenmolding,coverapieceofdampclothonthepapermaterial,andreciprocatesmoothlyonthesurfaceofthedampclothwithaspecialbrush.Afterlaying,usecardboardtoflattentheblankpartofthepapertype,andthencoveritwithadampcloth.Afterthepapertypemeetsthequalityrequirements,itisputintotheflatteningmachinetogetherwiththeironframetoheatandbake,andfinallyitiscutandarrangedbeforeuse.
Thewetprocesswasoriginallyamanualtappingmethod,butnowitisamechanicaltappingmethod.Thepapertypemadebythewetmethodhasclearstrokesanddeephandwriting,whichisverysmallfromtheoriginalversion,buttheprocessiscomplicatedandtheproductionefficiencyislow.
(2)Drypressingisamethodofmechanicallypressingpaper.Dividedintocoldpressingmethodandpressingmethod.Thepapertypemadebythecoldpressingmethodneedstobeputinadryingroomfordryingtreatment.Thehotpressingmethodonlyheatsthepressingplateoftheneedlepressingmachineto100-120℃,andthepapertypecanbeobtainedundertheactionofpressure.
Отливане на водещата плоча
Ontheplatecastingmachine,thepapertypeisusedasthetemplatetocasttheleadplate.Theplatecastingmachineisdividedintotwotypes:aflatplatecastingmachineandaroundplatecastingmachine.Theleadplatecastbythelithographicplatecastingmachineisusedforprintingbytheplatformmachine.Theroundplatecastingmachinecaststheleadplateintoanarcforprintingontherotarypress.
Ретуширане
Thebackofthecastleadshouldbeflattenedorsmoothed,andtrimmedanddrilledshouldbecarriedout.
Галванопластика
Platingironorchromiummetalonthesurfaceoftheleadplatebyelectroplatingcanincreasetheprintingenduranceoftheprintingplate.Theiron-platedclichéhasaprintingenduranceofabout100,000impressions,andthechrome-platedclichéhasaprintingenduranceofabout500,000impressions.