Ua rau Tire Screw (Wheel Stud / Bolt) Fracture thiab Kev Tiv Thaiv Zoo
Taw qhia
Log studs (tseem hu ua lub log tsheb los yog lub log bolts) yog qhov tseem ceeb ntawm kev ruaj ntseg fasteners uas ruaj lub tsheb log rau lub hub sib dhos. Lawv qhov tsis ua haujlwm tuaj yeem ua rau muaj kev puas tsuaj ntawm lub log sib cais, lub tsheb tsis muaj kev tswj hwm, thiab muaj xwm txheej loj. Nkag siab txog lub hauv paus ua rau lub log pob txha tawg thiab siv cov tswv yim tiv thaiv zoo yog qhov tseem ceeb rau kev nyab xeeb ntawm tsheb thiab kev ntseeg siab.
Qhov Tseem Ceeb Ua rau Log Stud Fracture
1. Daim ntawv thov Torque tsis raug
Tshaj -torquingyog ib qho ntawm feem ntau ua rau lub log stud tsis ua hauj lwm. Cov kev cuam tshuam niaj hnub no muaj zog heev thiab tuaj yeem yooj yim snap 12 hli ntsia liaj qhov rooj. Thaum cov txiv ntseej yog overtightened dhau qhov chaw tsim khoom tshwj xeeb, lub zog clamping ntau dhau ncav lub log studs tshaj lawv cov elastic txwv, ua rau muaj kev cuam tshuam mus tas li thiab tsim kev ntxhov siab uas ua rau qaug zog tsis ua haujlwm. Tshaj -tightening tuaj yeem ua rau lub log, sawb bolt threads, thiab warp nres rotors.
Hauv qab -torqueingyog sib npaug txaus ntshai. Tsis txaus torque ua rau lub log xoob uas wobble thaum lub sijhawm ua haujlwm, ua rau muaj kev ntxhov siab ntawm kev sib tw ntawm cov studs. Qhov no dynamic loading accelerates qaug zog tawg pib thiab propagation, nws thiaj li ua rau stud puas. Lub log kuj tseem yuav xoob zuj zus thiab thaum kawg poob ntawm lub tsheb.
Torque specification inconsistenciestam sim no muaj kev pheej hmoo ntxiv. Cov tsheb sib txawv nrog cov log zoo tib yam tuaj yeem muaj cov lus pom zoo sib txawv raws li cov khoom siv log, nres rotor tsim, thiab hub geometry. Piv txwv li, Subaru tsheb nrog 12 mm × 1.25 pitch studs tau pom cov kev hloov pauv ntawm 65.8 ft·lbs (cov qauv qub) mus rau 88.5 ft·lbs (cov qauv tshiab) rau tib tus lej, tsim kev tsis meej pem thaum kho.
2. Kev qaug zog
Kev qaug zog yog qhov kev puas tsuaj loj zuj zus uas tshwm sim thaum cov khoom raug cuam tshuam rau kev thauj khoom hauv qab nws lub zog tensile kawg. Log studs muaj kev qaug zog loading los ntawm:
Rotational dabtsi yog khoov: Raws li lub log rotates, lub stud ntsib cyclic dabtsi yog khoov kev nyuaj siab ntawm qhov kev hloov ntawm lub threaded feem thiab lub unthreaded shank, tshwj xeeb tshaj yog nyob rau hauv thawj cov xov uas muaj kev ntxhov siab concentration siab tshaj.
Kev vibration -induced fretting: Micro- txav ntawm lub log thiab lub hub tsim fretting corrosion thiab nto puas tsuaj uas ua raws li qhov chaw pib tawg
Nres thermal cycling: Rov ua cua sov thiab txias los ntawm kev ua haujlwm nres induces thermal stress superimposed on mechanical loading
Kev qaug zog tawg feem ntau pib ntawm cov kev ntxhov siab xws li cov hauv paus hniav, fillet radii, los yog corrosion pits, ces propagate perpendicular mus rau lub siab tshaj plaws tensile stress axis kom txog rau thaum tus ntoo khaub lig seem -section tsis tuaj yeem txhawb nqa lub load, ua rau tam sim ntawd brittle puas.
3. Hydrogen Embrittlement
Hydrogen embrittlement yog ib hom kev ua tsis zoo tshwj xeeb rau siab - lub zog log studs, feem ntau hu ua "silent killer" ntawm fasteners. Nws tshwm sim thaum atomic hydrogen nkag mus rau hauv cov hlau lattice thiab accumulates ntawm cov cuab yeej cuab tam (cov qoob loo ciam teb, dislocations, inclusions), txo cohesive zog thiab ua kom tawg propagation ntawm kev ntxhov siab nyob rau hauv cov ntaub ntawv ntawm ib txwm puas lub zog.
Rau lub log studs, hydrogen qhov chaw muaj xws li:
Cov txheej txheem tsim khoom: Acid pickling ua ntej plating thiab electroplating ua hauj lwm (zinc, cadmium, los yog chromium plating) tsim atomic hydrogen ntawm lub cathodic nto
Environmental raug: Corrosion ntawm stud nyob rau hauv kev pab cuam liberates hydrogen, tshwj xeeb tshaj yog nyob rau hauv lub xub ntiag ntawm noo noo thiab electrolytes
Cathodic tiv thaiv systems: Tshaj-kev tiv thaiv tuaj yeem tsim cov hydrogen ntau dhau ntawm cov hlau
Qhov kev pheej hmoo yog qhov loj tshaj rau siab - lub zog studs (Qib 10.9 thiab siab dua, feem ntau siab dua 30 HRC hardness). Thaum hydrogen nyob hauv qab txheej tuab xws li chrome phaj, nws tsis tuaj yeem yooj yim khiav, thiab ci yuav tsum pib li ntawm 4 teev tom qab plating (zoo tshaj hauv 1 teev) kom tsis txhob muaj kev puas tsuaj.
4. Stress Corrosion Cracking (SCC)
Kev ntxhov siab corrosion tawg yog qhov ua tsis tiav ntxov ntawm cov hlau nyob rau hauv kev sib xyaw ua ke ntawm tensile kev nyuaj siab thiab ib puag ncig corrosive. Rau lub log studs, SCC tuaj yeem tshwm sim thaum:
Chloride raug: Txoj kev ntsev (sodium chloride) thiab marine ib puag ncig tsim kev txhoj puab heev, tshwj xeeb tshaj yog rau stainless hlau studs
Ammonia compounds: Muaj tshuaj lom neeg ua liaj ua teb lossis kev lag luam
Sulfide ib puag ncig: Hydrogen sulfide los ntawm kev lag luam los yog decomposition ntawm lubricants
SCC tsim cov yam ntxwv tawg tawg uas tuaj yeem yog intergranular lossis transgranular nyob ntawm cov hlau thiab ib puag ncig. Tsis zoo li kev xeb dav dav, SCC tshwm sim nrog qhov pom tsawg kawg ntawm qhov chaw nres thaum cov kab nrib pleb nkag mus tob rau hauv cov khoom.
5. Corrosion thiab Environmental Degradation
General corrosiontxo qhov kev ua tau zoo ntawm tus ntoo khaub lig- ntu ntu ntawm cov stud, nce qib kev ntxhov siab. Kev tsim xeb ntawm cov txiv ntseej thiab cov pob txha tuaj yeem tsim qhov galling thiab ntes, yuav tsum muaj lub zog ntau dhau rau kev tshem tawm thiab ua rau cov xov puas.
Kev txhim kho corrosiontshwm sim nyob rau hauv qhov chaw kaw ntawm cov txiv ntoo, lub log, thiab lub hub, qhov twg oxygen depletion tsim anodic dissolution. Qhov no yog qhov teeb meem tshwj xeeb hauv cov cheeb tsam uas muaj kev siv ntsev hnyav los yog thaj chaw ntug dej hiav txwv.
Galvanic corrosion kujtshwm sim thaum cov hlau sib txawv sib cuag nyob rau hauv lub xub ntiag ntawm ib tug electrolyte. Piv txwv li, aluminium log hu rau steel studs tuaj yeem tsim cov galvanic hlwb uas ua kom cov pob txha tawg.
6. Cov khoom siv thiab kev tsim khoom tsis raug
Kev kho cua sov tsis raug: Kev kho cua sov tom qab xov dov (ntau dua li ua ntej) tuaj yeem ua rau muaj kev ntxhov siab ntxiv ntawm cov hauv paus hniav thiab txo qhov qaug zog.
Machined vs. dov threads: Txiav threads tsim kom muaj kev ntxhov siab thiab qhov tsis xws luag, thaum cov xov dov ua haujlwm- tawv tawv thiab tsim cov kev ntxhov siab zoo
Inclusions thiab voids: Sab hauv cov khoom tsis xws luag ua raws li kev ntxhov siab concentrators thiab tawg pib qhov chaw
Cov xov tsis zoo haum: Cov xov tsis zoo los yog cov xov tsis sib haum (xws li, yuam cov txiv ntoo mus rau imperial studs) tsim cov ntsiab lus thauj khoom thiab galling
Case- teeb meem nyuaj: Cov ntaub ntawv qhov tob tsis zoo lossis cov tub ntxhais hardness tsis sib haum tuaj yeem tsim kev tsis ua haujlwm ntawm rooj plaub -core interface
Kev tshawb fawb ntawm siab - lub zog fasteners tau pom tias cov xov dov yog qhov zoo tshaj plaws rau cov xov hlau rau kev qaug zog thiab kev ntxhov siab corrosion tawg, thiab kev kho cua sov yuav tsum tau ua ua ntej xov dov rau kev ua haujlwm zoo.
7. Kev puas tsuaj thiab kev teeb tsa tsis raug
Hla - xov: Pib lub noob txiv ntawm lub kaum sab xis ua rau cov xov puas thiab tsim kom muaj kev ntxhov siab
Kev puas tsuaj: Siv cov hammers lossis cov cuab yeej tsis tsim nyog los pib cov txiv ntoo ua rau cov xov puas
Lub log tsis sib haum: Siv cov log tsis raug lub voj voog lub voj voog txoj kab uas hla los yog qhov chaw nruab nrab tsim eccentric loading
Cov tshuab ntxhua khaub ncaws ploj lawm: Tsis muaj qhov chaw zaum kom zoo ua rau cov khoom thauj tsis sib xws
Re-torque degradation: Rov tshem tawm thiab rov nruab dua yam tsis muaj cov txheej txheem torque tsim nyog maj mam degrades kev sib koom ua ke
Cov kev tshawb fawb los ntawm Lub Tsev Haujlwm Saib Xyuas Kev Thauj Mus Los tau pom tias cov log tuaj yeem xoob txawm tias thaum xub thawj nruj, vim tias lub log nro thiab lub log clamping load deteriorate nrog rov tshem lub log thiab retorquing. Elastic yield ntawm cov khoom siv log ua rau cov txiv ntoo xoob los txhim kho thiab ua kom lub cev qaug zog.
Kev tiv thaiv zoo
1. Cov txheej txheem torque thiab kev teeb tsa kom raug
Ib txwm siv calibrated torque wrenches: Tsis txhob cia siab rau qhov cuam tshuam wrenches ib leeg rau qhov kawg nruj. Siv torque sticks (torque- txwv txuas ntxiv) ntawm cov phom phom yog tias tsim nyog, tab sis txheeb xyuas nrog lub torque wrench
Ua raws li cov neeg tsim khoom specifications: Nrog rau phau ntawv qhia kev pabcuam tsheb rau qhov tseeb torque qhov tseem ceeb, uas feem ntau yog li ntawm 75-88 ft·lbs rau 12 hli studs, sib txawv ntawm cov xov suab thiab cov khoom siv log
Siv lub hnub qub qauv nruj: Tighten lug ceev nyob rau hauv ib tug crisscross qauv los xyuas kom meej txawm load faib thiab tiv thaiv log warping
Re-torque tom qab pib installation: Txheeb xyuas lub zog tom qab 30 feeb lossis 40-80 km ntawm kev tsav tsheb, vim qee cov txiv ntseej yuav xoob me ntsis thaum pib teeb tsa
Tsis txhob rov qab siv lub zog torque - rau - tawm (TTY) bolts: Qee lub tsheb niaj hnub siv ib zaug - siv cov hlua khi uas yuav tsum tau hloov tom qab tshem tawm
Siv lub zog sib xws: Xyuas kom tag nrho cov studs tau txais kev sib npaug torque los tiv thaiv kev thauj khoom tsis sib xws
Rau cov tsheb Subaru tshwj xeeb, 1.25 xov suab tsim lub zog clamping siab dua 1.5 suab ntawm tib lub zog, yog li cov kws kho tsheb yuav tsum paub tias tus qauv 80 ft·lb torque sticks yuav overtighten fine -pitch studs.
2. Kev xaiv khoom thiab kev tswj xyuas zoo
Qhia cov qib zog uas tsim nyog: Match stud zog rau daim ntawv thov yuav tsum tsis muaj ntau dhau hardness uas ua rau embrittlement susceptibility
Yuav tsum tau dov threads: Qhia kom txias- dov threads es tsis txhob txiav threads rau superior qaug zog
Xyuas kom muaj kev kho cua sov kom zoo: Kev kho cua sov yuav tsum ua kom tiav ua ntej xov dov kom zoo dua microstructure thiab residual stress distribution
Xaiv cov khoom tiv thaiv corrosion-cov ntaub ntawv: Rau ib puag ncig hnyav, xav txog stainless hlau studs (nrog kev paub txog cov tshuaj chloride SCC txaus ntshai) lossis cov hlau alloy nrog cov txheej txheem tsim nyog
Tshawb xyuas cov ntaub ntawv pov thawj: Ua kom cov studs ua tau raws li cov qauv tsim nyog (ISO 898-1, SAE J429, ASTM cov qauv) nrog rau kev kuaj hlau kom zoo
Rau cov ntawv thov tseem ceeb, qhia kom meej tias txoj kab uas hla ntawm lub shank sib npaug ntawm cov kab hauv paus rau studs 3/4 nti thiab loj dua, txo qis kev ntxhov siab thiab nce elasticity.
3. Kev kho deg thiab txheej txheej kom zoo
Siv hydrogen- txheej zoo: Nyiam zinc-txheej txhuas flake coatings (xws li, Geomet, Dacromet) tshaj electroplated zinc los yog cadmium, vim cov txheej txheem no tsis qhia hydrogen
Yuav tsum tau hydrogen nyem ci: Rau electroplated siab- lub zog studs (Qib 10 thiab siab dua), ci ntawm 190-230℃rau yam tsawg kawg nkaus 8 teev (txog 24 teev rau Qib 12), pib li ntawm 4 teev (zoo dua 1 teev) ntawm kev ua tiav plating
Xav txog cov uas tsis yog -electrolytic txheej: Mechanical galvanizing, sherardizing, lossis zinc flake coatings tshem tawm hydrogen embrittlement txaus ntshai
Siv xov lubricants: Siv cov roj nplua nyeem pom zoo rau ntawm cov xov thiab hauv qab lub taub hau taub hau kom txo qis kev sib txhuam, xyuas kom meej lub zog torque- kev sib raug zoo, thiab tiv thaiv kev kub nyhiab
Tiv thaiv ib puag ncig corrosion: Siv cov tshuaj tiv thaiv kab mob, pleev xim, los yog cov tshuaj pleev thaiv hnub rau cov kab mob uas tshwm sim tom qab sib dhos
Txoj cai "4- Sijhawm Teev" yog qhov tseem ceeb: hydrogen embrittlement relief ci yuav tsum pib li ntawm 4 teev tom qab electroplating vim hydrogen atoms tsiv mus rau qhov chaw muaj kev ntxhov siab nyob rau hauv chav tsev kub, thiab ib zaug microcracks tsim, lawv yog qhov tsis xws luag txawm tias tom qab tshem tawm hydrogen.
4. Tsim kev txhim kho
Ua kom cov pob txha elasticity: Siv cov studs ntev tapped rau hauv qhov tob thiab ntxiv spacers nyob rau hauv cov txiv ntseej los txhim kho kev tiv thaiv kom xoob thiab qaug zog
Optimize xov geometry: Siv cov dov threads nrog lub hauv paus vojvoog kom zoo kom txo qis kev ntxhov siab
Siv los tiv thaiv -loosing nta: Xav txog tus kheej- xauv txiv ntseej (piv txwv li, Flexnuts™ uas faib cov khoom raws ntau cov xov), castellated txiv ntoo nrog cotter pins, los yog dual- txiv ntseej tshuab (piv txwv li, Log sab laug- tes txiv ntoo rau saum cov txiv ntoo txheem)
Xyuas kom lub log haum: Txheeb xyuas lub voj voog txoj kab uas hla, qhov nruab nrab qhov nruab nrab, thiab lub rooj zaum hom (conical, kheej kheej, los yog tiaj tus) phim cov stud thiab txiv ntseej tsim
Hub-centric tsim: Siv cov log uas nyob nruab nrab ntawm lub hub es tsis yog cov studs kom txo tau cov khoom khoov
Rau cov haujlwm hnyav -cov haujlwm ua haujlwm, ntau-jackbolt tensioners (Supernuts™) tuaj yeem hloov cov txiv ntoo ib zaug los faib cov khoom sib npaug thiab tiv thaiv kev ntxhov siab hauv thawj ob peb xov.
5. Cov txheej txheem tswj xyuas thiab tshuaj xyuas
Kev tshuaj xyuas qhov muag tsis tu ncua: Txheeb xyuas cov cim ntawm corrosion, xov puas, dabtsi yog khoov, los yog tawg thaum lub sij hawm log tsheb rotating thiab nres kev pab cuam
Torque pov thawj: Txheeb xyuas lub log txiv ntseej torque, tshwj xeeb tshaj yog tom qab tshem tawm lub log thiab rov nruab
Saib xyuas kom loosening: Siv los tiv thaiv -loosing kab cim ntawm txiv ntseej thiab studs; breakage ntawm lub alignment mark qhia tias loosening
Hloov cov studs puas tam sim ntawd: Tsis txhob rov siv lub pob zeb uas qhia cov xov puas, ncab, lossis corrosion
Ntxuav threads ua ntej installation: Tshem tawm cov av, xeb, thiab cov roj nplua nyeem qub kom ntseeg tau tias muaj kev sib koom tes thiab qhov tseeb ntawm qhov tseeb
Siv cov tshuaj tiv thaiv corrosion: Nyob rau hauv ib puag ncig hnyav, lub tsho tiv no nrog Krytox 227, Tef-Gel, lossis cov yeeb yaj kiab zoo sib xws- tsim cov tshuaj tiv thaiv corrosion uas kuj muab lubrication
Rau cov tsheb thauj mus los thiab cov tsheb lag luam, siv cov sijhawm tshuaj ntsuam xyuas uas siv cov torque wrenches thiab kev kuaj pom, nrog rau kev hloov tam sim ntawm txhua tus neeg xav tias fasteners.
6. Kev tiv thaiv ib puag ncig
Zam kev sib cuag hlau tsis sib xws: Siv cov tshuab ntxhua khaub ncaws los yog txheej txheej los tiv thaiv galvanic corrosion ntawm steel studs thiab aluminium log
Xyuas kom cov kua dej kom raug: Tsim lub log sib dhos kom tsis txhob sawv ntsug dej thiab ntsev ntau nyob ib puag ncig fasteners
Tiv thaiv los ntawm cov tshuaj: Tsis txhob raug ammonia, chlorides, thiab hydrogen sulfide hauv chaw cia khoom thiab kev pabcuam
Kev paub txog kev tiv thaiv Cathodic: Nyob rau hauv marine los yog faus daim ntaub ntawv, xyuas kom meej cathodic tiv thaiv systems tsis dhau -muaj peev xwm, uas yuav ua tau ntau tshaj hydrogen
Rau cov kev siv sab nrauv thiab dej hiav txwv uas hydrogen- ua rau muaj kev ntxhov siab corrosion tawg (Hi-SCC) tau ua rau muaj kev puas tsuaj rau cov txiv ntoo hauv cov cua turbine fasteners, tshwj xeeb yuav tsum tau them rau cov txheej txheem zoo thiab cov khoom tsis zoo, vim cov txiv ntoo tuaj yeem ua rau muaj kev cuam tshuam ntau dua rau Hi-SCC dua li cov ntaub ntawv tensile.
7. Kev soj ntsuam thiab kev sim siab heev
Tsis yog -kev kuaj kev puas tsuaj: Siv cov tshuaj ntsuam xyuas qhov sib nqus (MPI) lossis eddy tam sim no kuaj xyuas kom pom cov kab nrib pleb hauv studs thaum kho dua.
Hydrogen flux xyuas: Cov thev naus laus zis tshiab ntsuas cov nqi hydrogen permeation thaum lub sij hawm ci los xyuas kom tiav cov hydrogen tshem tawm
Kev kuaj qeeb qeeb: Rau kev tsim nyog ntawm cov ntaub ntawv tshiab los yog txheej txheej, chav kuaj SSRT rau ASTM G129 tuaj yeem txheeb xyuas hydrogen embrittlement susceptibility
Kev tswj xyuas cov txheej txheem: Siv cov ntaub ntawv pov thawj ua tiav ib sab ntawm cov khoom siv txuas ntxiv los saib xyuas cov plating da dej hydrogen embrittlement yam ntxwv ntawm ASTM F1940
Tsis muaj tam sim no muaj NDT txoj kev tuaj yeem ntseeg tau tias muaj hydrogen hauv cov lattice ua ntej tawg; kev tiv thaiv los ntawm kev tswj cov txheej txheem tsim khoom tseem muaj txiaj ntsig zoo dua li kev tshaj tawm tom qab- kev txhim kho kev txhim kho.
