Dab tsi yog Thermocoules?
Kuv tau tsim cov pwm txhaj tshuaj rau 22 xyoo tam sim no, feem ntau cov tshuab khiav thiab qhov kub thiab txias - cov cuab yeej tseem ceeb. Thermocouples tuaj nyob rau hauv yuav luag txhua qhov project sib tham, tab sis kuv tseem pom engineers spec'ing hom tsis ncaj ncees lawm los yog muab tso rau hauv qhov chaw phem. Figured kuv yuav sau qhov tseem ceeb thaum koj tab tom cuam tshuam nrog TC's hauv pwm ua haujlwm.
Lub hauv paus tsis muaj leej twg piav yog lawm
Ib lub thermocouple yog ob txoj hlua hlau sib txawv welded ua ke ntawm lub ntsis. Qhov kev sib tshuam ua rau me me voltage thaum nws kub. Koj tus maub los nyeem qhov voltage thiab hloov nws mus rau qhov kub thiab txias. Yooj yim txaus.
Qhov uas ua rau tib neeg mus txog: qhov voltage yog me me. Peb tab tom tham txog millivolts. Hom K ntawm 200℃tso tawm tej zaum 8 millivolts. Lub suab nrov los ntawm qhov sib txawv ntawm cov tsav tsheb, servo motors, cua sov thaiv - tag nrho cov uas tuaj yeem cuam tshuam koj lub teeb liab yog tias koj qhov kev teeb tsa tsis zoo. Kuv tau pom cov tshuab Husky tshiab tau nyeem 15℃tawm vim tias ib tus neeg khiav TC xov hlau nyob ib sab ntawm lub rhaub ua rau tib lub kav dej.
Hom J vs Hom K - Qhov txawv tiag tiag
Nyob rau hauv North America, feem ntau cov khw muag pwm default rau Hom J. Nws yog hlau thiab cov hlau tsis tu ncua, ua haujlwm zoo txog li 400℃ua ntej hlau pib oxidizing tsis zoo. Tus nqi qis dua Hom K. Yog tias koj khiav PP, PE, ABS, PS - Hom J ua haujlwm.
Hom K siv chromel-alumel. Mus siab dua, ruaj khov ntev dua - lub sij hawm, tab sis ntawm no yog qhov tsis muaj leej twg hais txog: Hom K sib txawv dua li Hom J thaum nws muaj hnub nyoog. Hom K nyiam nyeem qis thaum nws hnav. Hom J tuaj yeem mus rau ob qho tib si. Yog tias koj lub qhov rais txheej txheem nruj ntawm ib qho kev kho mob lossis cov khoom siv kho qhov muag, qhov kev hloov pauv tseem ceeb thaum koj teeb tsa koj lub sijhawm PM.
Cov cuab yeej European zoo li tuaj nrog Hom K ntsia. Thaum koj tab tom nrhiav los ntawm cov chaw tsim khoom yas txhaj tshuaj pwm txawv teb chaws, xyuas seb lawv muab tso rau hauv. Kuv tau muaj cov cuab yeej tshwm sim nrog Hom K thoob plaws, ces cov neeg siv khoom sim ntsaws rau hauv lawv cov hom J controllers uas twb muaj lawm. Kev nyeem ntawv yog txoj kev tawm vim tias tus maub los ua tus lej hloov pauv tsis raug.
Pwm-Masters thiab Synventive kub khiav tshuab xa nrog Hom J tus qauv rau Asmeskas kev lag luam. Husky mus rau Hom K ntawm lawv cov khoom Ultra Helix. Paub tias koj tau txais dab tsi ua ntej lub cuab yeej tsoo koj hauv av.
Qhov twg tiag Muab Lawv
Cov ntaub ntawv hais tias 3-5 hli los ntawm kab noj hniav. Lub ntiaj teb tiag yog messier tshaj qhov ntawd.
Ntawm qhov kub khiav nozzle, TC feem ntau zaum hauv ib lub qhov drilled rau hauv lub cev nozzle, tej zaum 10-15mm rov qab los ntawm lub rooj vag. Qhov ntawd yog ntsuas nozzle steel kub, tsis yaj kub. Cov yaj hauv cov dej ntws khiav kub dua - qee zaum 20-30℃kub dua nyob ntawm cov cua sov shear. Koj qhov teeb tsa ntawm 220℃ntawm tus maub los yuav txhais tau tias 245℃ntawm lub rooj vag. Tseem ceeb heev rau cov ntaub ntawv shear-rhiab zoo li POM.
Cavity nto sensing yog trickier. Koj laum ib lub qhov me me los ntawm sab nraum qab ntawm cov tub ntxhais los yog kab noj hniav thaiv, nres 2-3 hli ntawm qhov molding nto. Nyob ze dhau lawm thiab koj tsim kom muaj kev ntxhov siab - Kuv tau pom cores tawg txoj cai ntawm TC qhov tom qab ob peb puas txhiab txhaj tshuaj. Dhau deb rov qab thiab koj ntsuas qhov kub thiab txias, tsis yog cov yas pom zoo li cas.
Rau nruj- kev ua haujlwm siab ntev, qee qhov kev txhaj tshuaj molding cov cuab yeej zoo dua yuav muab ntau lub TC rau hauv ib kab noj hniav - ib qho ze ntawm lub rooj vag, ib qho kawg ntawm kev sau, tej zaum ib qho ntawm cov tuab tuab. Tau kim tab sis koj yeej paub tias muaj dab tsi tshwm sim thaum lub voj voog.
Grounded vs Ungrounded Junction
Grounded junction txhais tau hais tias TC xov hlau yog welded ncaj qha mus rau sab hauv ntawm cov hlau sheath. Teb ceev ceev, tej zaum 50-100 milliseconds. Ungrounded muaj qhov sib txuas insulated los ntawm sheath. Cov lus teb qeeb dua, zoo li 200-500 milliseconds.
Suab zoo li grounded yeej ib txwm zoo dua, txoj cai? Tsis heev.
Grounded TC's khaws hluav taws xob nrov los ntawm lub hnab. Yog tias koj tab tom khiav tus khiav kub nrog SCR- lub tshuab hluav taws xob raug rho tawm haujlwm thiab TC hauv av, koj yuav pom qhov ntsuas kub nyeem ntawv rov qab. Qee cov controllers lim qhov no zoo. Cov maub los pheej yig dua lossis cov PID laus dua tawm tsam nrog nws.
Ungrounded nqi me ntsis ntxiv, teb qeeb dua, tab sis muab koj lub teeb liab huv dua. Ntawm thaj chaw manifold uas cov thermal loj loj thiab lub sij hawm teb tsis yog qhov tseem ceeb, tsis muaj kev nkag siab zoo. Ntawm nozzle cov lus qhia uas koj xav tau cov lus teb ceev ceev rau lub sijhawm lub rooj vag valve, grounded ua haujlwm zoo dua txawm tias muaj teeb meem suab nrov.
Qhov teeb meem Drift
Txhua TC drifts dhau sijhawm. Cov xov hlau oxidize, kev sib tshuam degrades, calibration hloov. Yuav ceev npaum li cas nyob ntawm qhov kub thiab txias npaum li cas koj tso rau ntawm nws.
Khiav PEEK ntawm 380 degree, Hom K yuav ya 3-5℃hauv rau lub hlis ntawm kev siv ntau lawm. Khiav polypropylene ntawm 210 degree, tib TC yuav tuav calibration rau ob xyoos.
Ntawm no yog dab tsi catches neeg: lub drift yog gradual. Koj cov txheej txheem tsis dheev poob. Hloov chaw, koj qhov chaw maj mam zuj zus tuaj - flash pib tshwm, cov cim dab dej tau tob dua, lub sijhawm voj voog nkag mus vim qhov txias yuav siv sijhawm ntev dua. Los ntawm lub sijhawm ib tus neeg xav kuaj TC calibration, qhov teeb meem tau tsim rau ntau lub hlis.
Txhua qhov kev cai pwm tsim cov kev pabcuam ua haujlwm kuaj xyuas TC calibration thaum teem sijhawm PM. Yuav tsum yog tsawg kawg yog ib xyoos, ntau zaus nyob rau hauv siab - cov cuab yeej kub. Ib qho yooj yim handheld calibrator los ntawm Fluke los yog Omega raug nqi ob peb puas bucks. Tsis zam txim tsis muaj ib tug.
Installation Details That Matter
Lub caij nplooj ntoos hlav-loaded bayonet style yog tus qauv tam sim no. Kev sojntsuam swb mus rau hauv ib lub qhov drilled, lub caij nplooj ntoos hlav cia nws nias rau hauv qab. Connector ntawm lub ntsej muag pwm cia koj sib pauv sensors tsis rub lub cuab tam sib nrug.
Saib koj lub qhov tob. ntiav dhau lawm thiab qhov kev sojntsuam hauv qab tawm ua ntej lub caij nplooj ntoos hlav compresses - tsis muaj kev sib cuag, nyeem tsis raug. Sib sib zog nqus heev thiab tsis muaj lub caij nplooj ntoos hlav txaus kom muaj kev sib cuag thaum cov pwm kub thiab cov hlau nthuav dav. Feem ntau xav tau 1-2 hli ntawm caij nplooj ntoos hlav taug kev tom qab lub rooj zaum sojntsuam.
Qhov txoj kab uas hla yuav tsum ua kom haum rau qhov kev sojntsuam sheath txoj kab uas hla nrog tsawg kawg nkaus clearance. Sloppy haum txhais tau hais tias qhov kev sojntsuam tuaj yeem hloov mus ib puag ncig thiab kev sib cuag siab sib txawv. Feem ntau lub khw tsim qauv ntawm 3mm lossis 1/8 "probes.
Kev siv hluav taws xob yuav tsum nyob deb ntawm lub tshuab hluav taws xob hluav taws xob. Siv cov shielded TC txuas ntxiv cable, hauv av cov ntaub thaiv npog ntawm tus maub los kawg nkaus xwb. Kuv paub tias nws yog kev ntxias kom muab txhua yam ua ke hauv ib lub tais cable. Tsis txhob.
Thaum Tej Yam Tsis Zoo
Qhib Circuit Court yog qhov pom tseeb tsis ua haujlwm - tawg hlau, maub los nyeem max kub lossis cuam tshuam qhov yuam kev. Yooj yim rau kev kuaj mob.
Cov kev tsis sib haum xeeb yog ib feem ntawm kev sib cuag thiab qeeb drift. Kev sib cuag ib nrab tshwm sim thaum qhov kev sojntsuam tsis zaum zoo lossis lub caij nplooj ntoos hlav poob nro. Kev nyeem ntawv kub tsis txaus ntseeg, tej zaum yuav yog 10-20℃tawm. Tus maub los xav tias nws nyob ntawm qhov chaw teeb tsa, qhov tseeb steel kub sib txawv. Cov khoom tuaj tawm tsis ncaj ncees lawm tab sis cov temps tso saib zoo.
Kev sib txuas tsis zoo ntawm lub ntsaws yog ntau dua li qhov tseeb ntawm qhov tsis ua haujlwm. Pins tau corroded, tshwj xeeb tshaj yog rau cov cuab yeej uas khiav dej txias thiab pom condensation. Kev sib cuag tau khoov thaum ib tus neeg yuam lub connector. Kuv xav kwv yees 60% ntawm qhov "tsis zoo TC" hu kuv tau pom ntau xyoo dhau los yog qhov teeb meem ntawm kev sib txuas.
Yuav Hloov Sensors
Kev hloov OEM los ntawm koj tus neeg muag khoom kub kub raug nqi 3-4x qhov sib npaug sib npaug li cas. Mould-Masters lossis Husky branded TC feem ntau yog tib lub Watlow lossis Omega sensor nrog lawv cov lej cim rau ntawm nws.
Tsis muaj dab tsi tsis ncaj ncees lawm nrog kev mus tom qab kev muag khoom ntev npaum li koj phim cov specs: sojntsuam txoj kab uas hla, sheath ntev, hlws ris hom (grounded / ungrounded), TC hom (J / K), connector style. Lub precision pwm cov khoom lag luam lossis cov khoom siv hluav taws xob muaj xws li Grainger lossis MSC yog cov qauv kev teeb tsa.
Qhov twg OEM tseem ceeb: qhov tseeb maub los calibration. Cov neeg ua haujlwm kub khiav qee zaum muaj cov nyiaj them ua haujlwm nkhaus rau lawv cov TC tshwj xeeb. Generic sensor yuav nyeem ob peb degrees sib txawv. Feem ntau tsis muaj teeb meem. Ntawm cov txheej txheem tseem ceeb nws yuav.
Kab hauv qab
TC's yog cov khoom siv yooj yim ua haujlwm tseem ceeb. Lub sensor nws tus kheej tsis tshua muaj kev puas tsuaj loj - nws yog qhov kev teeb tsa, xaim, thiab kev saib xyuas uas ua rau muaj teeb meem. Tau qhov chaw zoo, khaws cov xov hlau kom huv si, tshawb xyuas calibration ib ntus, thiab lawv yuav muab cov lus qhia zoo rau koj rau xyoo.
Feem ntau cov teeb meem kuv daws teeb meem yog los ntawm theem tsim qauv - ib tug neeg spec'd hom tsis ncaj ncees lawm, muab TC rau hauv qhov chaw tsis zoo, lossis tsis xav txog kev tiv thaiv suab nrov. Tsim nyog siv sijhawm ua ntej nrog koj tus khub tsim pwm tsim kom tau txais TC qhov chaw thiab hom txheeb ua ntej cov hlau tau txiav. Txoj kev pheej yig dua li kho nws tom qab.
Puas muaj lus nug txog cov teeb meem thermocouple hauv koj lub cuab yeej? Tso ib nqe lus los yog hu rau. Tau nrog cov khoom no ntev txaus uas kuv tau pom tej zaum txawm tias koj muaj teeb meem dab tsi.