Hauv kev tsim khoom lag luam, engineers lub luag haujlwm rau kev sib khi feem ntau yog cov tswv cuab xav tau tshaj plaws ntawm pab pawg ua haujlwm.
Thaum lub tshuab ua haujlwm ib txwm, tsis muaj leej twg xav txog koj; tab sis ib zaug cov cuab yeej tsim cov xau (dej, roj, lossis roj) ntawm tus neeg siv khoom qhov chaw, thawj tus neeg tuav lub luag haujlwm yog undoubtedly lub sealing engineer.
Tus kws tsim qauv tsim thawj zaug tshuaj xyuas qhov ntev ntawm qhov trench, paub meej tias lawv raug kos raws li kev ua siab ntev. Lub tuam tsev IQC tom qab ntawd txheeb xyuas lub Hoobkas daim ntawv tshaj tawm, xyuas kom meej tias cov khoom muab los ntawm cov tuam txhab loj ua tau raws li txhua tus qauv tsim nyog. Thaum kawg, lub luag hauj lwm rau kev soj ntsuam tsis ua hauj lwm ntog rau ntawm lub sealing engineer.
Koj tshem tawm qhov tsis xws luag O-ring; nws qhov chaw tsis zoo, tsis muaj kab nrib pleb lossis cov cim qhia ntawm cov tshuaj corrosion. Qhov kev hloov pauv nkaus xwb yog tias nws tau flattened thiab tsis tuaj yeem rov qab los rau nws qhov qub.
Nyob rau theem no, tsuas yog tsom mus rau lub zog tensile thiab Shore hardness qhov tseem ceeb uas teev nyob rau hauv tus neeg muag khoom cov khoom siv tshwj xeeb yuav tsis txheeb xyuas qhov tseeb ntawm qhov ua tsis tiav.
Nyob rau hauv lub cheeb tsam ntawm cov ntaub ntawv polymer kaw, qhov ntev - lub sij hawm sealing kev ua tau zoo feem ntau txiav txim tsis yog los ntawm cov khoom hardness los yog tensile lub zog, tab sis los ntawm ib tug nquag underestimated parameter: compression set (CS).
Cia peb tshawb xyuas qhov ntsuas no hauv qhov tob ntawm peb qhov kev xav.
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Sealing - dab tsi yog qhov raug kaw?
Ua ntej sib tham txog compressive mus tas li deformation, nws yog ib qho tseem ceeb uas yuav tsum tau kho ib qho kev xav tsis zoo ntawm txhua yam: kev sib khi tsis yog nyob ntawm "kev thaiv" tab sis ntawm "kev txhawb nqa."
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Thaum koj ntxig ib lub silicone O-ntiv nplhaib rau hauv cov hlau zawj thiab zawm lub flange, cov silicone yog compressed (feem ntau mus rau qhov sib piv ntawm 15% - 30%).
Silicone yog cov khoom siv elastic heev. Thaum compressed, nws cov saw hlau molecular raug yuam kom distorted, tsim kom muaj zog rebound quab yuam (hu rau kev ntxhov siab) uas nrhiav kom rov qab mus rau nws qhov qub qub.
Qhov no rebound quab yuam nrees tawm tsam cov phab ntsa hlau; txoj kev xav, tsuav yog nws tshaj qhov siab ntawm cov kua dej sab hauv, qhov nruab nrab yuav tsis xau kiag li.
Yog li ntawd, cov ntsiab lus ntawm kev sib khi yog nyob rau hauv kev muab kev ywj pheej los ntawm silicone molecular chains nyob rau hauv compression, ua kom lawv ruaj khov rau cov hlau nto.
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Dab tsi ua rau lub foob tsis ua haujlwm?
Txij li thaum sealing cia siab rau lub zog rov qab los, yuav ua li cas yog tias lub zog no ploj mus?
Dab tsi yog compressive mus tas li deformation?
Peb flattened silicone gel los ntawm 25%, ci hauv qhov cub ntawm 120℃rau 70 teev, tom qab ntawd tshem tawm nws thiab tso cai rau nws txias thiab rov qab mus rau qhov qub.
Yog tias nws tuaj yeem rov qab kho nws qhov qub tuab, CS=0% (ib qho zoo meej elastomer uas tsis muaj nyob hauv qhov tseeb).
Yog hais tias nws flattens kiag li thiab tsis rov qab tag nrho, CS=100% (qhia tau tias nws tau dhau los ua yas).
Vim li cas molecular chains tsis "rov qab mus rau lawv qhov qub"? Qhov teeb meem nyob ntawm qib microscopic:
Qib Lub Cev - Kev Nyuaj Siab Kev Nyuaj Siab thiab Chain Segmentation Reorganization
Silicone yog tsim los ntawm kev sib tshuam ntawm cov saw ntev molecular. Thaum raug compression ntev ntawm qhov kub thiab txias,
Nws txo nws txoj kev ntxhov siab los ntawm kev maj mam zawv zawg thiab rov tsim kho.
Nws zoo li nias lub pob fluffy ntawm cov xov paj hauv qab ntawm ib lub thawv rau ib xyoos -Thaum koj muab nws tawm, nws twb tau hloov mus rau nws cov duab flattened thiab tsis tuaj yeem rov ua nws qhov qub fluffiness.
Lub cev "kev sib haum xeeb" no ua rau muaj kev poob qis hauv lub zog rov qab.
Chemical Level – Kev tawg thiab kev tsim kho ntawm tus ntoo khaub lig- txuas cov ntawv cog lus
Qhov no yog qhov tseem ceeb tshaj plaws. Lub elasticity ntawm silicone cia siab rau tus ntoo khaub lig- sib txuas cov khoom sib txuas ntawm cov saw hlau molecular (xws li sulfur-sulfur bonds).
Nyob rau hauv qhov kub thiab txias compression ntev, tus ntoo khaub lig thawj - txuas cov ntawv cog lus tawg, ua rau poob ntawm elastic traction quab yuam.
Qhov tseem ceeb tshaj, cov dawb radicals uas tsim los ntawm kev puas tsuaj yuav rov- tsim tus ntoo khaub lig tshiab- txuas cov ntawv cog lus nyob rau hauv cov ntaub ntawv compressed ntawm cov khoom- zoo kaw cov saw hlau molecular hauv "ntiaj teb." Txawm tias tom qab lub zog sab nraud raug tshem tawm, cov tshuaj tshiab no tiv thaiv cov khoom los ntawm kev rov qab mus rau nws qhov kev teeb tsa qub.
Lub cev plam + tshuaj recombination=compressive mus tas li deformation.
Tus nqi CS siab dua ua rau muaj kev sib tw silicone gel thiab kev sib cuag tsis muaj zog. Thaum kawg, thaum lub zog rov qab los ua tsis txaus piv rau cov kua dej siab, cov dej xau tshwm sim.
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Yuav ua li cas hais txog qhov no los ntawm engineering foundations?
Tam sim no peb nkag siab txog cov txheej txheem hauv qab no, peb yuav ua li cas zam qhov kev pheej hmoo no thaum tsim cov ntsaws ruaj ruaj thiab xaiv cov khoom siv?
1. Thaum txhais CS cov ntaub ntawv, ib txwm qhia meej txog qhov kev xeem.
Cov khoom vaj khoom tsev lub cev tau muab los ntawm tus neeg muag khoom feem ntau hais tias "mus tas li deformation nyob rau hauv compression: 25%.Txawm li cas los xij, ntawm qhov ntsuas kub npaum li cas, nyob rau hauv qhov sib piv compression, thiab ntev npaum li cas cov kev ntsuas no tau coj?
Yog tias tus nqi CS ntsuas ntawm 25% ntawm 100 degree, nws tuaj yeem nce mus rau ntau dua 50% raws li kev ua haujlwm tiag tiag ntawm 150℃vim kev kub ceev thiab oxidative kev laus.
Qhov kev xav tau tseem ceeb yog tias thaum ntsuas tus nqi CS, qhov ntsuas kub yuav tsum tsis txhob qis dua qhov ntsuas kub ntawm cov khoom, thiab lub sijhawm ntsuas yuav tsum yog tsawg kawg 70 teev lossis 168 teev. Tsuas yog cov ntaub ntawv no tuaj yeem ua qhov siv tau rau kev xaiv.
2. Tsom ntsoov rau ntawm tus ntoo khaub lig-txuas kev txuas es tsis yog qhov muag tsis pom kev ua kom tawv
Yog tias tus nqi CS tsis ua raws li qhov yuav tsum tau ua, tsis txhob sim them nyiaj los ntawm kev nce qib silicone gel hardness -hardness tsis tuaj yeem thim rov qab deformation mus tas li. Hloov chaw, kev cuam tshuam yuav tsum raug coj mus rau ntawm cov khoom siv tshuaj lom neeg hla -txoj kev txuas.
Noj NBR lossis EPDM ua piv txwv: ib txwm muaj sulfur vulcanization systems tsim sulfur-sulfur bonds nrog lub zog qis, uas muaj feem cuam tshuam rau kev tawg thiab hloov kho ntawm qhov kub thiab txias, ua rau cov txiaj ntsig CS tsis zoo.
Los ntawm kev siv cov txheej txheem peroxide vulcanization, carbon- carbon ib daim ntawv cog lus tau tsim, uas nthuav tawm lub zog siab thiab tiv taus kev sib cais thiab rov ua dua nyob rau hauv siab - kub compression, yog li txo qis compression deformation mus tas li.
Kev lag luam tawm - tawm yog qhov txo qis ntawm cov kua muag tsis kam ntawm peroxide- cov khoom vulcanized. Qhov no sawv cev rau qhov sib npaug ntawm kev ua tiav "tsis yog-tearability" thiab tuav "rebound properties".
3. Kev them nyiaj rau cov khoom siv CS attenuation los ntawm kev tsim qauv
Yog tias cov khoom siv tus nqi CS tau ua kom zoo rau nws qhov kev txwv lub cev (xws li, 30%), peb tuaj yeem ua li cas thiaj li ua kom muaj kev sib khi txuas ntxiv mus ntev - siv sijhawm ntev?
Txij li thaum peb paub tias nws yuav plam ib co resilience, peb yuav tsum muab qhov kev poob no rau hauv cov nyiaj compression thaum tsim groove qhov ntev.
Txawm li cas los xij, qhov sib piv compression tsis tuaj yeem nce ntxiv mus tas li. Thaum lub compression tus nqi siab heev (ntau tshaj 40%), kev ntxhov siab nyob rau hauv lub polymer nce exponentially, ua rau cov neeg kho tshuab tawg ntxov ntawm molecular chains thiab thiaj li ua kom CS deterioration.
Txoj hauv kev ua tau zoo tshaj plaws yog rau cov kws tsim qauv tsim qauv thiab cov khoom siv engineers los sib koom ua ke ua kom muaj kev sib haum xeeb raws li qhov kev ntxhov siab so nkhaus -ib qho uas tsis cuam tshuam rau silicone kev ncaj ncees thiab tsis ua kom muaj kev sib khi txaus txaus tom qab kaum xyoo.
Tsim ib lub foob tseem ceeb txhais tau tias dhau los ua phooj ywg thiab yeeb ncuab ntawm lub sijhawm.
Ib tus kws tshaj lij sealing tiag tiag tsis yog tsom rau kev ua kom muaj dej tsis sib haum thaum lub sijhawm ua tiav.
Lawv qhov kev txhawj xeeb yog nyob rau hauv seb, tom qab peb, tsib, lossis kaum xyoo- nyob rau hauv qhov rov qab raug rau qhov kub thiab txias siab heev - cov saw hlau molecular tseem yuav nyob ruaj khov rau saum npoo hlau.
Yog tias koj muaj lub foob uas ua rau xau ntau zaus tab sis tsis tuaj yeem txheeb xyuas qhov laj thawj, lossis pom tus neeg muag khoom lub rooj khoom tsis meej pem - xav tiv tauj peb tus kws muag khoom muag nrog koj cov duab kos thiab cov qauv ua tsis tiav.