Dab tsi yog qhov cuam tshuam ntawm Tight Khoov ntawm Internal Resistance Hlau thiab Nws Cov Hluav Taws Xob Ua Haujlwm?

Lub PTFE sheath tej zaum yuav zoo nyob rau sab nraud, tab sis yog hais tias cov hlau tsis kam nyob rau hauv yog overstressed thaum khoov, muaj ib tug kub qhov chaw tsim nyob rau hauv. Qhov khoov yog qhov chaw nquag ntawm kev kub nyhiab thaum ntxov, thiab qhov laj thawj tseem ceeb feem ntau yog kev puas tsuaj rau cov hlau, kev puas tsuaj uas tsis tuaj yeem kuaj pom los ntawm ib qho twg ntawm kev tshuaj xyuas sab nrauv. Nkag siab txog cov txiaj ntsig ntawm kev sib tw nruj hauv cov hlau tsis muaj zog PTFE lub rhaub ua haujlwm yog qhov tseem ceeb rau txhua tus neeg qhia lossis txhim kho zoo li lub tshuab tso cua sov hauv kev xav tau kev lag luam.

Teb ntawm Internal Resistance Hlau rau dabtsi yog khoov
Sab hauv txhua lub PTFE immersion rhaub yog cov hlau tsis muaj hlau. Feem ntau cov hlau siv yog NiCr (nickel chromium) alloy ( Nichrome ). Cov hlau yog lub plawv ua haujlwm ntawm lub rhaub; thaum muaj hluav taws xob khiav los ntawm nws, resistive cua sov tshwm sim. Nyob rau hauv feem ntau tsim cov hlau yog twisted mus rau hauv ib tug zoo meej helical kauj los yog nteg raws li ib tug ncaj, homogeneous strand thoob plaws hauv lub ntev ntawm PTFE sheath.

Tom qab ntawd lub rhaub yog khoov rau hauv ib qho duab. Cov hlau tsis kam yog ces khoov rau hauv tib lub nkhaus. Lub tshuab teb ntawm cov hlau yog ib txoj haujlwm ntawm txoj hauj lwm txheeb ze rau qhov khoov:

Nyob rau sab nraud ntawm qhov khoov - Cov hlau yog muab tso rau hauv qhov nro. Yog tias lub vojvoog khoov loj txaus, cov hlau yog elastically stretched thiab yuav rov qab mus rau nws qhov qub ntev thaum lub zog dabtsi yog khoov tawm. Tab sis yog tias qhov khoov yog qhov ntse heev, cov hlau hla dhau nws cov kev txwv elastic thiab tau txais cov yas ruaj khov uas ua rau nws hauv zos thinner.

Cov hlau yog nyob rau hauv compression kev nyuaj siab nyob rau hauv lub khoov. Yog hais tias koj khoov nws sharply, lub puab voj voog ntawm cov hlau yuav tau compressed thiab cov hlau yuav buckle / kink / pawg. Nyob rau hauv ib tug helical hlau tsim, sib law liag lem yuav kov ib leeg los yog ua unevenly spaced.

Cov Khoom Siv Hluav Taws Xob: Kub Spot thiab Stretched Hlau
Hluav taws xob tsis ua hauj lwm ntawm ntau yam tshwm sim los ntawm qhov nruj khoov nyob rau hauv cov hlau tsis kam ntawm PTFE rhaub, ua rau txo qis kev ua haujlwm thiab lub neej ua haujlwm luv.

Localized Resistance nce
Thaum cov hlau raug nthuav tawm thiab khoov tawm sab nraud, cov hlau tsis sib haum tau thinner thiab tus ntoo khaub lig- ntu ntu txo qis . Qhov hluav taws xob tsis kam yog qhov sib npaug ntawm tus ntoo khaub lig- ntu ntu kom ib ntus nyias muaj qhov loj dua nyob rau ib chav tsev ntev. Qhov kev nce hauv cheeb tsam hauv cheeb tsam txhais tau hais tias rau tib lub sijhawm tam sim no khiav los ntawm tag nrho lub tshuab cua sov cov khoom khoov ua rau cov cua sov ntau dua (lub zog=I2R). Qhov no tsim ib qho chaw kub kub, ib feem me me ntawm lub tshuab cua sov uas qhov kub thiab txias ntau dua li cov cua sov so.

Hot Spots Implications
Qhov chaw kub yog lub luag haujlwm rau ntau yam kev ua tsis tiav:

Oxidation ntawm cov hlau tsis kam - Qhov ceev oxidation ntawm NiCr alloy qhov kub siab dua. Oxidation ua rau muaj kev tiv thaiv ntxiv ntxiv, tsim kom muaj lub voj voog tawm tswv yim zoo uas thaum kawg yuav ua rau yaj - dhau los lossis qhib Circuit Court.

Degradation ntawm ib puag ncig PTFE sheath - PTFE tuaj yeem ua haujlwm tsis tu ncua ntawm 110 degree, txawm hais tias qhov kub kub hauv zos tuaj yeem siab tshaj 200℃lossis ntau dua. Ntawm cov kub no, PTFE pib deteriorate, poob dielectric zog thiab tej zaum emit corrosive byproducts. Thaum lub overstressed khoov lub sheath yuav soften, deform los yog tawg.

Kev qaug zog- ua rau txo qis txoj sia
Thaum cov yas deformation tsis ua txhaum txoj hlua khi txawm tias thaum khoov, kev ntxhov siab tshwm sim. Cov hlau swells thiab sib cog lus tom qab rov ua dua thermal cycling (kub mus txog qhov kub thiab txias rov qab mus rau ambient). Qhov chaw ntawm qhov khoov hauv qhov nro yog raug rau cyclic mechanical strain, ua rau qaug zog tsis ua haujlwm. Ib cov hlau uas tuaj yeem muaj sia nyob tau ntau xyoo hauv kev tsim ncaj ncaj tuaj yeem ua tsis tiav hauv lub hlis ntawm kev khoov nruj.

Teeb meem ntawm Bunching thiab kev sib cuag ntawm lem
Nyob rau hauv coiled hlau cua kub ntsiab, nruj khoov rau sab hauv ntawm lub nkhaus yuav compress lub coil ua nyob ib sab lem mus rau kev sib cuag. Yog tias qhov hloov pauv, cov hluav taws xob tam sim no tuaj yeem dhia hla lub helix, yog li txo qhov ntev ntawm cov xaim hauv cheeb tsam ntawd. Qhov no txo ​​qis qhov kev tiv thaiv hauv zos (tawm tsam qhov ncab- cov nyhuv xaim) - tab sis ua rau lwm qhov nyuaj - tam sim no congestion thiab tsis sib npaug ntawm cov cua sov. Qhov chaw tiv tauj yuav arc lossis cua sov hauv zos, rov ua qhov chaw kub.

Hauv kev muaj tiag, qhov ntsuas hluav taws xob tiv thaiv ntawm lub tshuab hluav taws xob tuaj yeem qhia qhov tseem ceeb thaum xub thawj. Nyob rau hauv ib tug multimeter, tag nrho cov hlau tsis kam yog nyob rau hauv specification yog li ib tug me ntsis kub qhov chaw yuav tsis pom. Feem ntau, qhov tsis ua hauj lwm tshwm sim tom qab lub sijhawm ua haujlwm, qee zaum ntau pua teev, qee zaum tsuas yog ob peb hnub, thaum qhov kub ntawm qhov kawg melts los ntawm cov xaim, lossis cov PTFE cuam tshuam tso cai rau luv luv rau hauv av.

Internal hlau kev ncaj ncees tom qab khoov kuaj
Lub PTFE sheath tsis pob tshab yog li cov hlau sab hauv tsis tuaj yeem raug kuaj pom. Zoo-pab manufacturers siv X-ray tshuaj ntsuam xyuas cov hlau layout nyob rau hauv ib tug tiav lawm khoov rhaub. Daim duab X-ray qhia pom:

Txawm qhov sib nrug ntawm kauj tig (tsis muaj bunching lossis sib cais)

Tsis muaj kinks, khoov hnyav lossis thinning ntawm cov hlau

Repeatability ntawm hlau txoj hauj lwm txheeb ze rau centerline ntawm sheath

Ib qho zoo tsim khoov tuav tus thawj hlau geometry ntawm rhuab mandrel dabtsi yog khoov thiab ncej- khoov annealing. Cov xaim nyob rau sab nraud ntawm qhov khoov tsis nruj dhau qhov kev txwv elastic thiab cov xaim ntawm sab hauv tsis buckle. Hlau qhov sib txawv yog qhov sib xws uas yuav pab txhawb txawm tias cua sov thoob plaws qhov ntev ntawm lub rhaub.

Yuav ua li cas Thermal Cycling ua rau me me dabtsi yog khoov puas
Lub tshuab hluav taws xob me ntsis overtightened bent tuaj yeem tiv taus lub zog pib- nce thiab txawm tias ob peb hnub ua haujlwm tas mus li. Txawm li cas los xij, thermal cycling (cua sov thiab txias) ua rau muaj kev puas tsuaj rau ob txoj hauv kev:

Differential expansion - Cov hlau thiab PTFE sheath muaj qhov sib txawv thermal expansion coefficients. Txhua lub voj voog tsim cov kev ntxhov siab ntawm cov xaim- sheath contact, localized at the curve where the wire is twb stressed.

Progressive oxidation - Raws li txhua qhov chaw kub ua tiav qhov kub siab, ib txheej me me ntawm oxide yog tsim rau ntawm cov hlau. Cov oxide txheej no tsis tshua muaj hluav taws xob thiab nkig ntau dua. Thaum kawg cov hlau yuav nyias nyias thiab oxidised uas nws tawg qhib.

Peb tau pom los ntawm cov kev paub dhau los uas yog tias koj khoov lub rhaub kom tsawg dua 5 mus rau 6 zaug OD lub vojvoog nws feem ntau ua tsis tiav hauv 3 mus rau 12 lub hlis raws li lub voj voog ib txwm muaj, qhov zoo ib yam ntawm cov cua sov uas muaj qhov khoov txaus yuav kav li 5 xyoos lossis ntau dua.

Xaus: Hluav Taws Xob Kev Ntseeg yog Mechanical Accuracy
Lub sij hawm ntev hluav taws xob muaj kev ntseeg siab yog ua raws li kev tiv thaiv cov hlau sab hauv los ntawm overstressing thaum khoov. Kev khoov nruj yuav ntswj los yog khi cov hlau ua rau thaj chaw kub kub uas txhawb nqa oxidation, ua rau lub PTFE sheath puas thiab ua rau hlawv ntxov ntxov. Kev ntsuam xyuas hluav taws xob thawj zaug tuaj yeem dhau mus tab sis qhov kev puas tsuaj zais tsis tau qhia nws tus kheej hauv kev pabcuam.

Qhov kev nkag siab no ua rau muaj kev txiav txim siab dav dav, tias qhov zoo ntawm lub tshuab cua sov yog kev sib xyaw ua ke ntawm cov khoom siv hluav taws xob thiab kev ua haujlwm hluav taws xob. Khoov-rhuab mandrel dabtsi yog khoov, tom qab- khoov annealing thiab X-ray pov thawj yog kev ntxhov siab-dawb thiab siv tib cov txheej txheem tsim khoom uas khaws kev ncaj ncees ntawm cov xaim sab hauv. Kev qhia txog qhov qis qis qis tsis txaus los tiv thaiv cov hlau, tiv thaiv qhov kub thiab txias, thiab muab lub neej ua haujlwm ntev uas cov ntawv thov kev lag luam xav tau.