Cov teebmeem ntawm Aluminium thiab Tin ntawm Bronze Gears
Copper alloy (bronze) gears muaj cov khoom tshwj xeeb uas pab txo qis hnav hauv bronze-on-steel sib cuag. Bronze iav yog siv nyob rau hauv cov iav reducers thiab yog mated rau steel worm gears. Bronze spur iav yog siv nyob rau hauv lwm yam khoom siv uas yuav tsum tau mating nrog steel spur zog.
Nyob rau hauv txhua rooj plaub, lub steel nto yog ib qho nyuaj tshaj li bronze nto. Kev xaiv ntawm bronze-on-steel ob peb ua ke yog ua raws tib lub hauv paus ntsiab lus raws li bronze tes tsho bearings mated rau nyuaj steel shafts.
Kev hnav ntawm bronze-on-steel ua rau kev txi ntawm cov bronze nrog me me los yog tsis hnav ntawm cov hlau.
Bronze-on-steel kev sib txhuam yog tsawg tshaj li steel-on-steel kev sib txhuam.
Ntawm qhov sib txawv ntawm qhov nrawm dua, cov zaj duab xis puv lossis hydrodynamic lubrication yuav cais cov hlau-ntawm-steel khub, tab sis ntawm qhov qis dua, cov asperities (surface roughness) ntawm cov khoom sib txuas yuav sib cuag. Qhov no ua rau muaj kev hnyav hnyav ntawm ob lub ntsiab lus steel. Rau bronze-on-steel khub, lub zog steel asperities shear lub zog bronze asperities.
Vim hais tias ntawm cov kev xav no, metallurgical thiab mechanical engineers tau tsim ib tsev neeg ntawm bronze alloys uas txo cov bronze hnav thaum muab tag nrho cov zoo ntawm bronze-on-steel khub.
Qhov xav tau bronze yuav muaj cov khoom nram qab no:
Lub zog nqa cov loads xav tau.
Tsawg coefficient ntawm kev sib txhuam nrog hlau.
Tsawg kawg hnav ntawm bronze.
Ntau cov kabmob bronzes muaj cov hlau lead kom txo cov coefficient ntawm kev sib txhuam, txawm li cas los xij, cov hlau lead cais tawm ntawm cov khoom khov khov thiab muaj nyob nruab nrab ntawm cov tooj liab alloy crystals. Qhov no ua rau cov khoom tsis muaj zog, thiab txawm tias muaj txiaj ntsig zoo rau lub tes tsho bearings, txhuas yuav tsum tau khaws cia kom tsawg kawg nkaus kom muaj zog iav bronzes. Qee cov iav bronzes muaj me me ntawm qhov no intergranular coj los txhim kho machinability.
Kev sib xyaw ua ke zoo tshaj plaws ntawm cov khoom hnav yog pom nyob rau hauv ob pawg tooj liab alloy:
Aluminium thiab manganese bronzes muaj zog thiab txi rau hnav ntawm steel mating qhov chaw. Cov alloys no muaj cov matrix muaj zog rau hauv uas ib qho nyuaj heev yog embedded. Qhov steel mating yuav tsum yog ib qho nyuaj heev, thiab ob qho tib si yuav tsum muaj qhov zoo nkauj heev. Cov bronzes no yuav tsis tsim ib qho kev sib txhuam qis bronze txheej ntawm cov hlau.
Tin bronzes tau ntxiv dag zog los ntawm kev daws teeb meem ntawm tin hauv tooj liab, txog li 10% tin. Cov tin ntxiv ua rau muaj zog, nyuaj intergranular theem uas yog nplua nuj nyob rau hauv tin. Cov tin atoms deform lub tooj liab matrix txaus los pab inhibit plam ntawm cov siv lead ua txheej, thiab cov theem intergranular pab ua kom tawv. Tin bronze ua ib qho kev sib txhuam qis bronze tso rau ntawm mating steel tivthaiv. Vim li no, tin bronze yog cov alloy ntawm kev xaiv rau cov tsis-ferrous iav.
Lub asperities ntawm txhuas thiab manganese bronze tso rau ntawm hlau tsis zoo li cov tin bronze. Lub asperities ntawm txhuas bronze nws thiaj li tsim txhuas oxide cov ntsiab lus, uas yog heev abrasive. Manganese bronze muaj txhuas thiab (ntau npaum li cas) zinc. Zinc oxide yog abrasive, thiab zinc nyob rau hauv tooj liab matrix txhawb nqa hnav thaum mating nrog hlau. Tin muaj qis dua affinity rau oxygen dua aluminium lossis zinc.
"Nyob" thiab qhov tshwm sim ntawm ciam teb yog dab tsi ua tin bronze thiaj li zoo tagnrho rau mating nrog hlau. Thaum cov nyiaj txaus ntawm bronze asperities yog embedded rau saum npoo, hnav yog txo thiab kev sib txhuam yog txo.
Qhov yooj yim tooj liab-tin alloy rau cov iav tau hloov zuj zus mus rau hauv ib qho ntawm tsib nrov iav bronzes. Cov alloys no tau teev nyob rau hauv specification ASTM B 427-93A. Muaj me ntsis variation. 12% tin alloy muaj ntau theem nyuaj. Copper alloy C92900 yog ntau haiv neeg, vim nws muaj cov ntsiab lus txhuas ntawm 2.5%. Qhov no tso cai rau kev ua haujlwm zoo, thiab cov khoom siv lead ua yuav embed rau hauv cov xov xwm abrasive thaum hnav. Cov ntsiab lus npib tsib xee (3.5%) hauv cov hlau no muaj txiaj ntsig zoo heev. Nws tsub kom corrosion kuj thiab txhawb nqa me me siv lead ua ntau thiab tsawg hauv castings. Qhov me me ntawm cov muaju, cov tshuaj sib cais tsawg dua thiab qhov siab dua lub cev zoo.
Cov iav bronzes no tsis tuaj yeem tsim los ntawm cov txheej txheem forging xws li extrusion, kos duab, dov lossis forging. Lawv yuav tsum tau siv los ua castings. Cov ntsiab lus siab tin tuaj yeem ua rau extruded billets tawg. Cov uas muaj 8% tin tuaj yeem nruam nruam thiab kos rau cov kab me me. Cov ntsiab lus tin qis tuaj yeem raug extruded thiab kos rau cov kab me me. (Cold) kev kos duab ua kom lub cev muaj zog tshaj cov khoom cam khwb cia. Tsis muaj kev txhim kho hauv cov khoom sib txhuam.
Cov iav bronzes tiag tiag tsuas tuaj yeem nrum los ntawm qee txoj hauv kev. Ob qho tib si xuab zeb casting thiab txias casting tso cai rau shrinkage kab noj hniav thiab non-metallic (abrasive) inclusions. Kev nruam nruam tshem tawm cov teeb meem no. Lub nruam nruam bar lossis raj yog muab rho tawm los ntawm cov pwm txuas nrog rau lub cub tawg uas muaj cov kua hlau. Lub inlet ntawm cov pwm yog submerged tob hauv qab saum npoo ntawm cov kua hlau. Tsis muaj slag tuaj yeem ncav cuag thaj chaw no thiab cov kua hlau ua raws li lub chaw cia khoom noj, yog li tsis txhob muaj cov kab noj hniav shrinkage.
Txij li thaum xyoo 1950s, kev nruam nruam ntawm cov iav bronze tau hloov zuj zus mus suav nrog ntau yam kev txhim kho. Kev nce qib hauv kev siv thev naus laus zis tsis tu ncua tau ua rau cov cam khwb cia qws thiab cov khoom siv raj nrog cov khoom siv lead ua me me. Qhov no ua rau cov khoom zoo sib xws, muaj zog nruam txuas ntxiv. Iav bronze tsim los ntawm txoj kev no yog superior rau iav bronze uas ua los ntawm lwm txoj kev. Yield zog, cuam tshuam lub zog, thiab hardness yog zoo heev. Hnav kuj tseem txhim kho.
