Cov txheej txheem extruding siv rotating ntsia hlau mechanisms thauj, yaj, thiab cov ntaub ntawv los ntawm kev tuag nyob rau hauv kev tswj lub siab thiab kub. Cov ntsia hlau ua haujlwm raws li ob qho tib si conveyor thiab cov cuab yeej sib xyaw, hloov cov ntaub ntawv raw rau hauv cov ntawv txuas ntxiv los ntawm kev siv tshuab shear thiab thermal zog.
Yuav Ua Li Cas Ntsia Hlau Mechanisms Ua Haujlwm hauv Extrusion
Cov txheej txheem extruding ua haujlwm los ntawm cov ntsia hlau helical rotating hauv ib lub thoob rhuab. Raws li cov ntsia hlau tig, cov khoom txav mus rau pem hauv ntej los ntawm peb thaj chaw sib txawv: thaj chaw pub noj txais cov khoom siv raw thiab pib compression, thaj chaw hloov pauv siv lub zog nce ntxiv thaum melting tshwm sim, thiab thaj chaw metering muab homogenized yaj ntawm lub siab zoo mus rau qhov tuag. Cov ntsia hlau geometry-tshwj xeeb tshaj yog nws cov channel qhov tob, suab, thiab compression piv- txiav txim siab npaum li cas cov khoom hloov pauv los ntawm cov khoom khov mus rau khov.
Lub tshuab tso siab rau cov dej ntws ntau dua li qhov kev hloov pauv zoo hauv feem ntau cov teeb tsa. Cov khoom siv ua raws li cov phab ntsa ntawm lub thoob thaum lub hau ntswj rotates hauv qab nws, tsim cov kev sib txheeb ze uas ua rau ob qho tib si rau pem hauv ntej thiab kev sib txhuam kub. Qhov no txawv ntawm cov twj tso kua mis los yog augers. Hauv ib lub tshuab ntsia hlau, qhov ntev ntev - mus rau - txoj kab nruab nrab ntawm 20: 1 txog 30: 1, nrog 24: 1 yog tus qauv thoob plaws kev lag luam. Cov kab sib sib zog nqus hauv cov khoom noj maj mam hloov mus rau qhov chaw sib sib zog nqus, tsim kom muaj qhov sib piv feem ntau ntawm 2: 1 thiab 4: 1.
Cov ntsia hlau lub davhlau geometry kuj tseem ceeb heev. Davhlau dav feem ntau ntsuas nyob ib ncig ntawm 10% ntawm txoj kab uas hla ntawm lub thoob - dav dav dav hlau pov tseg ntev thiab tsim kom muaj cua sov ntau dhau, thaum lub dav hlau nqaim tso cai rau cov khoom xau ntau dhau los ntawm kev tshem tawm. Cov ntsia hlau niaj hnub suav nrog cov kaum sab xis uas cov davhlau tau raws li cov hauv paus hniav los tiv thaiv cov khoom stagnation, thiab ntau qhov tshwj xeeb sib xyaw seem xws li Maddock distributors lossis thaiv kev ya davhlau los txhim kho cov khoom sib xws.
Ib Screw Versus Twin Screw Systems
Ib leeg ntsia hlau extruders dominate plastics ntau lawm vim lawv txoj kev yooj yim, kev ntseeg tau, thiab tus nqi qis. Lawv ua tau zoo ntawm qhov siab - ntim tas mus li qhov uas cov khoom siv zoo ib yam tso cai rau kev yooj yim melting thiab siv. Cov ntaub ntawv nce linearly los ntawm cua sov cheeb tsam nrog kuj maj mam shearing. Kev ua kom nrawm ncav cuag 20 mus rau 80 meters ib feeb rau cov txheej txheem yooj yim xws li polyethylene, txawm tias xav tau ntau cov ntaub ntawv xws li siab - zog aluminium alloys qeeb mus rau 2-3.5 meters ib feeb.
Twin ntsia hlau extruders siv ob qhov sib txuas ntawm cov ntsia hlau uas tuaj yeem tig mus rau tib qho kev taw qhia (co-rotating) lossis cov lus qhia rov qab (counter-rotating). Co-rotating designs, qhov twg ob lub hau ntswj tig ua ke, muab kev sib xyaw ua ke zoo tshaj plaws los ntawm cov khoom hloov pauv ntawm cov ntsia hlau hauv daim duab - yim qauv. Qhov kev teeb tsa no tswj cov txheej txheem nyuaj nrog ntau yam khoom siv ntxiv, muab tub lim, lossis kev txhawb nqa zoo dua. Lub intermeshing geometry tsim nws tus kheej -so kev ua uas tiv thaiv cov khoom tsim thiab tso cai rau cov qauv ntsia hlau modular haum rau cov txheej txheem tshwj xeeb.
Counter-rotating twin screws ua rau muaj kev hloov pauv zoo nyob rau hauv C-zoo li cov chav nruab nrab ntawm kev sib tw davhlau. Qhov no tsim muaj zog conveying quab yuam nrog qis shear kev nyuaj siab, ua rau lawv zoo tagnrho rau shear- cov ntaub ntawv rhiab heev xws li PVC compounds. Cov chav kaw kaw kuj tseem ua kom zoo dua lub siab tsim kom ncaj qha extrusion yam tsis muaj twj ntxiv.
Kev tshawb fawb los ntawm Pacific Northwest National Laboratory tau pom tias cov qauv ntxaib ntsia hlau siab tshaj tuaj yeem ua rau siab tshaj -kev ua haujlwm zoo li 7075 thiab 2024 txhuas ntawm qhov nrawm nrawm heev -7.4 meters ib feeb piv rau cov pa 3.5 meters ib feeb-thaum ua tiav cov khoom siv tshuab uas tshaj ASTM tus qauv. Cov tshuab no tshem tawm cov txheej txheem homogenization ib txwm thiab txo cov kev kho cua sov.
Core Process Parameters
Kev tswj qhov kub thiab txias ua haujlwm los ntawm ntau thaj chaw ywj pheej raws lub thoob. Cov cua kub sab nraud muab lub hauv paus thermal zog, thaum lub tshuab shear los ntawm cov ntsia hlau tig ua rau muaj kev kub ntxhov ntxiv. Cov txheej txheem extruding yuav tsum muaj kev tswj xyuas kom zoo: rau cov thermoplastics, qhov kub thiab txias feem ntau yog nyob ntawm 170℃txog 270℃nyob ntawm hom polymer. Khoom noj khoom haus extrusion ua haujlwm ntawm 100℃thiab 200 degree. Aluminium extrusion yuav tsum tau billet preheating rau 450-500℃ua ntej nkag mus rau qhov tuag.
Screw ceev ncaj qha cuam tshuam lub sij hawm nyob, shear rate, thiab throughput. Twin ntsia hlau tshuab feem ntau khiav ntawm 100 thiab 600 rpm rau cov ntawv thov zaub mov, thaum cov yas sib xyaw siv tau 20-150 rpm nyob ntawm viscosity thiab kev sib xyaw. Kev nrawm dua ua kom cov cua sov ua kom sov tab sis txo lub sijhawm nyob rau hauv cov txheej txheem thermal. Tsawg ceev tso cai rau melting zoo ntawm cov ntaub ntawv crystalline tab sis txo cov nqi ntau lawm.
Lub siab ua kom nce mus txog qhov ntev ntawm cov ntsia hlau, ncav cuag qhov tseem ceeb tshaj plaws ntawm qhov tuag nkag. Cov txheej txheem tsim 30-700 MPa nyob ntawm cov khoom siv thiab cov duab geometry tuag. Qhov siab no ob qho tib si tsav cov khoom siv los ntawm kev txwv kev tuag qhib thiab cuam tshuam cov khoom siv. Hydrostatic extrusion tshuab tuaj yeem ua tiav qhov siab txog li 1,400 MPa los ntawm ib puag ncig lub pob zeb nrog cov kua nplaum, tab sis qhov no tseem tshwj xeeb vim cov khoom siv tsis yooj yim.
Tuag tsim tswj cov khoom kawg geometry. Qhov qhib qhov tuag tsim cov dej ntws tawm uas ua rau rov qab- siab thoob plaws hauv cov ntsia hlau, cuam tshuam rau tus cwj pwm melting thiab sib tov. Flow channels yuav tsum tswj cov kev sib tw nrawm kom tsis txhob muaj qhov tsis xws luag. Av ntev- ntu ncaj ntawm qhov tawm ntawm qhov tuag- tswj kev poob siab thiab nto tiav. Cov neeg tsim qauv kuj tseem yuav suav txog qhov tuag o, qhov twg cov ntaub ntawv viscoelastic nthuav dav tom qab tso tseg.
Muaj peev xwm ua cov khoom siv
Polymers thiab plastics sawv cev rau daim ntawv thov loj tshaj plaws. Ib leeg ntsia hlau extruders tsim cov kav dej, profiles, nplooj ntawv, zaj duab xis, thiab hlau txheej los ntawm cov thermoplastics xws li polyethylene, polypropylene, PVC, thiab polystyrene. Qhov xwm txheej tas mus li suits huab hwm coj ntau lawm ntawm cov khoom lag luam. Twin ntsia hlau compounders muab lub hauv paus resins nrog cov xim, stabilizers, nplaim taws retardants, thiab reinforcing fibers. Cov iav thiab cov pa roj carbon fiber ntau tshaj 15% xav tau cov tshuab tshwj xeeb pub noj thiab cov ntsia hlau geometries los tiv thaiv fiber ntau tawg thaum tswj kev tawg.
Hlau extrusion los ntawm cov ntsia hlau mechanisms feem ntau siv rau txhuas, txawm tias tooj liab, magnesium, thiab qee cov hlau alloys kuj ua tiav. Aluminium billets rhuab mus rau 450-500℃dhau los ntawm kev tuag nyob rau hauv kev kub siab los tsim cov qauv duab rau aerospace, tsheb, thiab kev tsim kho. Aircraft fuselage thav duab, tis spars, thiab tsaws iav Cheebtsam feem ntau siv 2024 thiab 7075 txhuas alloys extruded rau hauv complex profiles. Cov txheej txheem tuaj yeem tsim cov seem hollow nrog intricate geometry tsis yooj yim sua los ntawm machining lossis forging.
Kev ua zaub mov ua haujlwm ntiav ntxaib ntsia hlau extruders feem ntau. Cov txheej txheem extruding tsim siab shear thiab kub tej yam kev mob uas ua rau cov hmoov txhuv nplej siab gelatinization ntau tshaj 98% nyob rau hauv cov khoom nplej, thaum cov protein ntau nthuav thiab realign thaum lub sij hawm texturization. Qhov no tsim cov khoom noj txom ncauj nthuav dav, noj tshais cereals, pasta, thiab cog -raws li nqaij analogs. Cov txheej txheem tsis cuam tshuam rau kev ntxhib los mos, tsw kev loj hlob, thiab kev khaws cov khoom noj. Cov ntsiab lus noo noo feem ntau yog li ntawm 20-40% kom ua tiav lub khob noom cookie zoo sib xws thaum extrusion. Kev ua noj thiab kev sib sau ua ke tshwm sim ib txhij hauv ib kauj ruam txuas ntxiv.
Cov ntawv thov tshuaj tsom mus rau kub-kub extrusion rau cov tshuab xa tshuaj. Twin ntsia hlau extruders muab cov khoom xyaw tshuaj nquag nrog cov khoom siv polymer ntawm qhov kub thiab txias, tsim kom muaj cov khoom tawg yooj yim uas txhim kho tus nqi tawg rau cov tshuaj tsis zoo. Tswj tau -tso tawm formulations, transdermal thaj ua rau thaj, thiab implantable pab kiag li lawm tshwm sim los ntawm ua tib zoo tsim ntsia hlau configurations thiab thermal profiles. Cov txheej txheem tas mus li ua rau muaj kev tswj xyuas zoo dua li kev sib xyaw ua ke.
Direct thiab Indirect Extrusion Methods
Cov txheej txheem extruding tuaj yeem ua tiav los ntawm cov txheej txheem sib txawv. Direct extrusion, tseem hu ua rau pem hauv ntej extrusion, thawb lub billet los ntawm ib tug nyob ruaj ruaj tuag siv ib tug ram los yog rotating ntsia hlau. Lub billet thiab thawv txav ua ke nyob rau hauv tib txoj kev. Qhov kev npaj no, thaum mechanically yooj yim, ua rau muaj kev sib txhuam tseem ceeb ntawm cov phab ntsa thiab cov thawv ntim khoom. Qhov kev sib txhuam ntawd ua rau kom muaj zog ntxiv thiab cuam tshuam rau saum npoo. Cov kev xav tau quab yuam pib siab thaum cov khoom tsis txaus siab los sau lub thawv, poob thaum lub sij hawm ruaj khov extrusion, tom qab ntawd rov ua dua thaum lub billet thins ze ua tiav. Qhov kawg "qab kawg" feem ntau tau muab pov tseg vim kev txhawj xeeb tsis zoo.
Indirect extrusion txav cov tuag mus rau qhov chaw nres tsheb billet siv lub hollow ram. Lub thawv nce mus thaum lub ram thiab tuag nyob twj ywm. Qhov no tshem tawm kev sib txhuam ntawm cov phab ntsa thiab cov thawv ntim khoom, txo qis extrusion quab yuam los ntawm 25-30% thiab ua kom nrawm dua nrog qhov zoo dua. Txoj hauv kev kuj tso cai rau extrusion ntawm me me hla ntu thiab txo qhov nyiam mus rau qhov tawg. Txawm li cas los xij, hollow ram tsim txwv qhov siab tshaj plaws qia ntev, txwv cov khoom ntev piv rau cov qauv ncaj qha.
Hydrostatic extrusion nyob ib puag ncig lub billet tag nrho nrog cov kua nplaum tshwj tsis yog ntawm qhov chaw tuag. Cov kua dej xa cov quab yuam sib npaug thaum tshem tawm cov khoom- mus rau - cov khoom sib txhuam. Cov roj castor feem ntau ua haujlwm raws li qhov nruab nrab ntawm qhov siab mus txog 1,400 MPa. Txoj kev no tso cai rau ntau dua extrusion piv, qis dua kub, thiab nce ductility. Qhov chaw siab sib xws txo qhov tsis xws luag thiab tso cai rau kev ua cov ntaub ntawv nkig uas yuav tawg raws li cov txheej txheem. Cov kev cai sealing thiab kev tuav cov dej tsis yooj yim tiv thaiv kev siv ntau dhau ntawm cov ntawv tshwj xeeb.
Temperature Regimes thiab lawv cov teebmeem
Kub extrusion ua hauj lwm saum toj no cov ntaub ntawv lub recrystallization kub - feem ntau 50-60% ntawm kiag li melting point. Qhov kub siab txo qhov muaj zog tawm los thiab ua kom cov ductility kom siab tshaj plaws. Aluminium extrusion ntawm 450-500℃yuav tsum muaj zog ntawm 250-12,000 tons nyob ntawm seb qhov loj me thiab tuag complexity. Lub tshav kub tiv thaiv kev ua haujlwm hardening, tso cai rau kev hloov pauv huab cua hauv ib qho dhau los. Txawm li cas los xij, kev pheej hmoo oxidation nce ntxiv, cov qauv nplej tuaj yeem coarsen, thiab cov teeb meem saum npoo tuaj yeem txhim kho yam tsis muaj kev tiv thaiv zoo los yog txheej txheej.
Txias extrusion nyob rau hauv chav tsev kub ua qhov chaw nrog superior mechanical zog los ntawm kev ua hauj lwm hardening. Cov txheej txheem ntxiv dag zog rau cov ntaub ntawv thaum txhim kho nto tiav thiab qhov ntev precision. Lub zog xav tau txo qis piv rau kev ua haujlwm kub, thiab tsis muaj oxidation tshwm sim. Cov ntawv thov feem ntau suav nrog kev cuam tshuam extrusion rau cov raj collapsible, cov roj teeb, thiab cov khoom me me los ntawm cov hlau zoo li txhuas, txhuas, tooj liab, thiab tin. Cov txheej txheem yuav tsum tau cov ntaub ntawv uas muaj ductility siab thiab txwv kev ua tiav complexity vim muaj kev nyuaj siab ntws.
Sov extrusion occupies qhov nruab nrab ntawm kev ua haujlwm txias thiab kub. Kev ua haujlwm kub poob qis dua cov ntsiab lus recrystallization tab sis saum toj no ambient tej yam kev mob. Qhov kev cuam tshuam no txo cov rog piv rau kev ua haujlwm txias thaum tswj kev ua kom zoo dua li kub extrusion. Cov txheej txheem haum rau cov ntaub ntawv uas qhia tau tias kub luv luv- tus cwj pwm nkig ntawm qhov kub siab tshaj - thiab muab kev nrawm dua li kev ua haujlwm txias. Kev cuam tshuam ib puag ncig thiab cov nqi cuab yeej txo qis rau kev ua haujlwm kub siab.
Kev lag luam daim ntawv thov thiab Scale
Kev lag luam plastics ua ntau lab tons ib xyoos ib zaug los ntawm cov ntsia hlau extruders. Cov txheej txheem extruding tsim profile extrusion rau lub qhov rais thav duab, qhov rooj trim, automotive weatherstripping, thiab cov khoom siv. Zaj duab xis thiab cov kab ntawv tsim cov khoom ntim, cov yeeb yaj kiab ua liaj ua teb, thiab cov khoom siv thermoformable. Cov yeeb nkab extrusion muab cov kav dej hauv nroog, cov khoom siv hluav taws xob, thiab cov txheej txheem kev lag luam. Peb- txheej coextrusion rau PVC yeeb nkab siv cov tub ntxhais ua npuas ncauj kom txo qhov hnyav los ntawm 25% thaum muab cov ntsiab lus rov ua dua tshiab hauv nruab nrab txheej. Hlau thiab cable txheej tiv thaiv cov kab xa hluav taws xob thiab kev sib txuas lus sib txuas.
Aluminium extrusion ua haujlwm rau aerospace thiab kev thauj mus los tseem ceeb. Boeing thiab Airbus lub dav hlau suav nrog ntau pua tus qauv extruded rau ib lub dav hlau -stringers uas txhawb nqa lub cev nqaij daim tawv, lub rooj taug kev nrog meej T- qhov chaw geometry, tis ua ntug nrog txoj kev nkhaus, thiab hydraulic tubing. Kev lag luam automotive siv extruded Cheebtsam rau kev sib tsoo cov qauv, bumper reinforcements, ru tsev rails, thiab tshav kub exchangers. Kev tsim kho vaj tsev ntiav cov duab kos duab rau kab hlau rhuav phab ntsa, hnub ci vaj huam sib luag thav duab, thiab cov tswv cuab ntawm cov qauv. Extrusion ratios-qhov pib ntoo khaub lig-section faib los ntawm qhov kawg ntawm cheeb tsam-feem ntau ncav cuag 10: 1 txog 100: 1 thaum tuav qhov zoo.
Cov chaw tsim khoom noj khoom haus cia siab rau extrusion rau cov khoom tsim khoom thiab siab - ntim ntau lawm. Noj tshais cereal kab ua haujlwm tsis tu ncua, ua noj thiab puffing nplej sib tov thaum lawv tawm hauv qhov tuag. Cov khoom noj khoom txom ncauj tsim cov cheese puffs, pob kws chips, thiab nthuav cov khoom lag luam los ntawm kev ya raws flashing thiab tswj kev nthuav dav. Cov khoom noj tsiaj extrusion muab cov khoom noj khoom haus sib xyaw nrog kev tswj kev ntxhib los mos, tsim kibble nrog cov ntom ntom thiab zom cov yam ntxwv. Nqaij analog ntau lawm siv cov nroj tsuag cov proteins uas dhau los ua cov txheej txheem thermomechanical, tawm nrog fibrous textures mimicking tsiaj cov ntaub so ntswg.
Pharmaceutical nruam manufacturing nce adopts ntxaib ntsia hlau extrusion. Cov tuam txhab hloov pauv los ntawm kev ua batch ua rau cov kab sib xyaw ua ke uas cov hmoov pub mis, yaj sib tov, strand tsim, thiab pelletization tshwm sim ua ntu zus. Kub-melt extrusion ua rau kev tsim cov tswv yim ua tsis tau los ntawm compression lossis ntub granulation. Amorphous solid dispersions txhim kho bioavailability rau BCS Class II tshuaj. Txuas ntxiv- tso tawm matrices muab cov tshuaj pharmacokinetics tswj. Cov txheej txheem analytical technology kev koom ua ke tso cai rau tiag tiag - sijhawm saib xyuas thiab hloov kho.
Cov Khoom Siv Tsim thiab Configuration
Kev tsim lub thoob siv cov hlau kheej kheej uas muaj zog nrog cov khoom siv hauv qhov chaw. Ntau qhov chaw kub muaj qhov tshwj xeeb cua sov thiab cov cua txias. Qee cov qauv siv hluav taws xob hluav taws xob induction cua sov rau cov lus teb sai dua thiab kev siv hluav taws xob qis dua piv rau cov cua sov tiv thaiv. Barrels faib longitudinally rau ntsia hlau tshem tawm thiab txij nkawm, nrog bolted flanges sealing lub rooj sib txoos. Sab hauv hauv ob sab phlu ntawm hnav- cov alloys resistant ncua kev pab cuam lub neej thaum ua cov ntaub ntawv abrasive.
Screw fabrication feem ntau pib nrog machinable steel cores, tom qab ntawd siv cov kev kho deg rau cov chaw tseem ceeb. Flame hardening muaj kev tiv thaiv yooj yim rau lub teeb- daim ntawv thov. Nitriding hardens tag nrho saum npoo los tiv thaiv abrasive hnav. Hard alloy caps ntawm lub davhlau ya davhlau muab qhov siab tshaj plaws hnav tsis kam qhov twg kev sib cuag nrog lub thoob tshwm sim. Qee cov ntsia hlau muaj qhov dhuav hauv nruab nrab rau cov dej los yog cov roj ncig, cov chaw ua kom txias kom tsis txhob yaig ntxov ntxov los yog tswj qhov kub ntawm cov cua sov- cov ntaub ntawv rhiab heev.
Tsav tshuab ob peb lub tshuab hluav taws xob los ntawm gearboxes kom ua tiav qhov xav tau torque ntawm kev ua haujlwm nrawm. Hydraulic tsav lub zog loj extrusion presses rau hlau sib sau. Direct-tsav roj presses xa cov siab zoo mus txog 35 MPa tab sis ua haujlwm qeeb ntawm 50-200 mm / s. Accumulator dej tsav mus txog 380 mm / s rau steel extrusion txawm tias 10% siab poob ntawm cov hlab ntsha. Lub cev muaj zog yuav tsum muaj ntau yam los ntawm fractional horsepower rau chav kuaj mus rau ntau txhiab horsepower rau ntau lawm-scale polymer compounding kab.
Tuag tooling yuav tsum tau machining thiab kev kho cua sov kom tiv taus thermal cycling thiab abrasive hnav. Cov cuab yeej ua haujlwm kub kub zoo li H13 nplua txhuas extrusion tuag, thaum tungsten carbide ua haujlwm hnyav heev. Cov neeg tsim khoom tuag ua kom zoo tshaj qhov ntws channel geometry kom txo qis kev poob siab thaum tswj kev sib tw nrawm. Simulation software qauv cov ntaub ntawv ntws cov qauv, kwv yees qhov chaw nyob hauv cov choj tuag thiab txheeb xyuas cov cheeb tsam uas muaj qhov tsis xws luag. Tuag suav nrog kev tswj qhov kub thiab txias los tswj cov thermal expansion thiab tswj cov khoom lag luam qhov ntev.
Txheej txheem tswj thiab optimization
Niaj hnub nimno extruders integrate faib tswj systems saib xyuas kaum ob ntawm tsis ib txhij. Cov txheej txheem extruding tau txais txiaj ntsig los ntawm kev tswj qhov kub thiab txias rau txhua cheeb tsam chim siab uas tswj cov chaw teeb tsa hauv ± 2℃los ntawm PID algorithms. Lub siab transducers ntawm ntau qhov chaw kuaj xyuas cov kev txwv ntws los yog cov khoom siv hloov pauv. Torque sensors nyob rau hauv lub tsav system qhia load variations ntawm pub tus nqi hloov pauv los yog cov khoom inconsistencies. Kev ntsuas dhau los txheeb xyuas cov nqi tsim khoom thiab suav cov kev siv hluav taws xob tshwj xeeb.
Kev txheeb xyuas lub sij hawm nyob hauv kev faib tawm qhia tias cov khoom siv ntev npaum li cas hauv extruder. Cov kev faib me me qhia cov ntsaws ntsaws nrog tsawg kawg backmixing, tsim nyog rau kev ua haujlwm zoo ib yam. Cov kev tshawb fawb Tracer txhaj cov xim xim pulses thiab saib xyuas lawv qhov tshwm sim, qhia qhov chaw tuag lossis txoj hauv kev nyiam. Screw tsim kev hloov kho cov teeb meem no-kneading blocks nce kev sib xyaw ua ke, thaum xa cov khoom txo lub sijhawm nyob.
Cov kev ntsuas zoo nyob ntawm daim ntawv thov tab sis feem ntau suav nrog qhov ntev ntev, qhov ua tiav, cov khoom siv kho tshuab, thiab kev sib xyaw ua ke. Cov txheej txheem kev txheeb cais tswj xyuas cov kev hloov pauv raws sijhawm, ua rau muaj kev cuam tshuam ua ntej muaj teeb meem tshwm sim. Hauv -kab ntsuas kab ntsuas phab ntsa tuab ntawm cov yeeb nkab extrusion, saib xyuas cov xim sib xws hauv kev tsim cov yeeb yaj kiab, thiab txheeb xyuas qhov hnyav molecular faib hauv reactive extrusion. Kaw - voj tswj kho cov txheej txheem tsis tuaj yeem tswj xyuas cov lus qhia tshwj xeeb.
Scale-nce los ntawm chav kuaj mus rau kev tsim khoom yuav tsum tau ua tib zoo saib xyuas cov duab geometric thiab dynamic zoo sib xws. Cov extruders me me ua haujlwm ntawm 50 g / h qhia cov qauv tsim rau cov tshuab tuav 50,000 kg / h. Lub zog tshwj xeeb tawm tswv yim- ua haujlwm rau ib chav tsev loj- qhia kev ceev ceev thiab kev xaiv xaiv. Shear rate scaling kom zoo sib xws molecular degradation los yog sib tov efficiency thoob qhov ntau thiab tsawg. Kub profiles hloov kho rau qhov sib txawv ntawm qhov sib txawv- mus rau- ntim qhov sib piv raws li cov kab uas hla ntawm 18 hli mus rau 400 hli ntau lawm tshuab.
Kev saib xyuas thiab kev txiav txim siab ua haujlwm
Screw hnav tshwm sim feem ntau ntawm cov lus qhia dav hlau qhov twg hlau - mus rau - hlau kov nrog lub chim tshwm sim. Abrasive fillers zoo li iav fibers, ntxhia talc, los yog hlau oxides ua kom cov degradation. Kev tshuaj xyuas tsis tu ncua ntsuas qhov dav dav dav, piv rau cov qauv tshwj xeeb. Thaum clearances ntau tshaj 0.5 hli, to flows txo siab tiam thiab throughput drops. Txhim kho cov kev pabcuam txuas ntxiv cov khoom tshiab rau hauv cov davhlau ya nyob twg thiab rov ua kom zoo dua qub. Qee qhov kev ua haujlwm tuav cov ntsia hlau thaub qab kom txo qis qis thaum lub sijhawm kho dua tshiab.
Kev hloov lub thoob liner yuav tsim nyog tom qab kev pabcuam txuas ntxiv nrog cov ntaub ntawv abrasive. Kev tshuaj xyuas qhia pom cov qauv hnav-grooves los ntawm cov ntsia hlau sib cuag, pitting los ntawm corrosion, los yog thermal tawg los ntawm kub cycling. Liner lub tes tsho nruab rau hauv lub thoob lub ntsiab, tso cai rau kev hloov pauv ntawm qhov hnav tsis muaj khawb tag nrho cov hlab ntsha siab. Cov ntaub ntawv liner ntau yam los ntawm nitrided steel rau kev pabcuam dav dav rau cov raj bimetallic nrog tungsten carbide sab hauv qhov chaw rau kev siv huab.
Kev tu tuag tiv thaiv cov khoom paug thaum hloov xim lossis hloov cov qauv. Purge compounds lub cev scour deposits los ntawm ntws raws thiab tuag nto. Cov qib kev tshem tawm sib txawv yog tsom rau hom av tshwj xeeb- cov khoom siv carbonized degradation, hla- xim tsis muaj kab mob, lossis cov nplaum nplaum uas tawv tawv. Kev tu txhua yam nrog txhuam los yog da dej ultrasonic tshem tawm cov khoom seem. Qee qhov siab -kev ua haujlwm zoo electropolish tuag nto kom ua tiav daim iav tiav uas tiv thaiv fouling.
Gearbox lubrication ua raws li cov chaw tsim khoom tshwj xeeb nruj me ntsis. Synthetic roj tuav cov loads siab thiab kub nyob rau hauv twin ntsia hlau tsav tsheb ciav hlau. Cov kev ntsuam xyuas roj pom cov khoom hnav thaum ntxov, tiv thaiv kev puas tsuaj loj. Kev soj ntsuam kev vibration txheeb xyuas cov kabmob degradation lossis iav hniav puas ua ntej tawg. Coupling kev sib raug zoo ntawm lub cev muaj zog, gearbox, thiab cov ntsia hlau yuav tsum nyob twj ywm nyob rau hauv nruj tolerances kom tsis txhob hnav ntxov ntxov.
Kev nyab xeeb thiab Environmental Factors
Cov kub kub ua rau muaj kev phom sij thoob plaws hauv cov txheej txheem. Lub thoob qhov chaw ncav cuag 300℃lossis ntau dua, thaum cov khoom extruded tawm molten. Cov khoom siv tiv thaiv cov neeg muaj xws li kub- hnab looj tes tiv thaiv, daim npog ntsej muag, thiab nplaim taws- khaub ncaws retardant. Lub tshuab tiv thaiv tiv thaiv kev sib cuag nrog cov khoom sib hloov. Cov chaw nres tsheb ceev yuav tsum nkag mus tau los ntawm txhua qhov chaw nres tsheb.
Kev phom sij txaus ntshai tshwm sim los ntawm kev tsim cov khoom siv los yog qhov cua tsis zoo. Tuag blockages ua rau siab spikes uas tuaj yeem rupture chim los yog tshuab flanges sib nrug. Siab nyem li qub muab kev tiv thaiv overpressure. Cov tshuaj hloov pauv yuav tsum tau ceev faj cov txheej txheem kom tsis txhob tso cov ntaub ntawv thaum lub sij hawm hloov lim. Purge cov ntaub ntawv thiab cov khoom pib yuav tsum tau sau kom zoo yam tsis muaj cov neeg ua haujlwm raug rau cov dej kub yaj.
Kev tsim cov fume tshwm sim thaum qee cov ntaub ntawv overheat lossis degrade. PVC ua haujlwm yuav tsum muaj qhov cua kom ntes hydrogen chloride yog tias thermal decomposition tshwm sim. Fluoropolymers zoo li PTFE tso cov tshuaj perfluorinated saum toj no kev nyab xeeb kub. Cov pa tso pa hauv zos ntes cov vapors ntawm qhov chaw. Kev saib xyuas huab cua kom ntseeg tau tias cov qib raug nyob qis dua li kev txwv kev ua haujlwm.
Kev siv hluav taws xob sawv cev rau tus nqi ua haujlwm tseem ceeb thiab kev cuam tshuam ib puag ncig. Cov ntsia hlau ua tau zoo tsim kom txo cov khoom siv hluav taws xob tsawg los ntawm kev ua kom zoo dua cov channel geometry. Rwb thaiv tsev txo cov cua sov los ntawm cov thoob khib nyiab. Thaum tshav kub kub rov qab systems ntes pov tseg thermal zog rau preheating feedstock los yog chaw cua sov. Lub cev muaj zog hloov pauv zaus tsav kho qhov nrawm kom haum rau qhov xav tau ntau dua li khiav tsis tu ncua ntawm qhov siab tshaj plaws. Cov kev tshawb fawb qhia tau hais tias ntxaib ntsia hlau tshuab tuaj yeem ua tiav 25-40% kev txuag hluav taws xob piv rau cov laus ib leeg ntsia hlau tsim rau cov khoom sib npaug.
Kev Tshawb Fawb thiab Kev Tsim Kho Tshiab
Kev tsim khoom siv ntxiv tau vam khom rau cov khoom siv extruder hloov kho-tsim filaments. Twin ntsia hlau compounding tsim tshwj xeeb blends incorporating nruam fibers, conductive hais, los yog functional additives. Precise txoj kab uas hla tswj thiab txhua yam khoom zoo sib xws txiav txim siab luam ntawv zoo. Qee lub tshuab extrude ncaj qha rau hauv 3D tshuab luam ntawv, tshem tawm cov theem nrab pelletization.
Reactive extrusion combines tshuaj synthesis nrog mechanical ua nyob rau hauv ib chav tsev ua haujlwm. Polymerization, saw extension, grafting, thiab crosslinking tshwm sim nyob rau hauv cov ntsia hlau raws. Qhov no tshem tawm cov kuab tshuaj-raws li cov tshuaj tiv thaiv thiab cov nqi sib cais. Lub sij hawm nyob luv luv ntawm qhov kub siab ua kom cov txheej txheem tsis tuaj yeem ua tsis tau nyob rau hauv batch reactors. Cov ntawv thov suav nrog kev ua haujlwm ntawm cov polymers, tsim cov thermoplastic elastomers, thiab ua kom cov yas biodegradable.
Cov txheej txheem analytical technology kev koom ua ke muab tiag -lub sij hawm muaj pes tsawg leeg xyuas. Raman spectroscopy soj ntsuam cov qauv molecular los ntawm cov qhov rais pob tshab hauv lub thoob. Ze ntawm -infrared sensors ntsuas cov dej noo, cov khoom sib piv, thiab crystallinity. Mass spectrometers coj cov vapors los ntawm qhov chaw nres nkoj kom taug qab qhov kev tshem tawm tsis zoo. Cov ntaub ntawv no pub cov txheej txheem tswj hwm qib siab uas kho tus nqi pub mis, ntsia hlau nrawm, thiab thermal profiles tau txais.
Cov cuab yeej simulation txuas ntxiv nce mus rau qhov tseeb thiab muaj peev xwm. Computational fluid dynamics qauv peb- qhov seem ntws nyob rau hauv cov ntsia hlau raws, kwv yees kev sib xyaw ua haujlwm thiab qhov chaw nyob hauv lub sijhawm faib khoom. Finite element tsom xam xam cov kev ntxhov siab faib rau hauv cov ntsia hlau thiab cov thoob nyob rau hauv kev khiav hauj lwm loads. Cov menyuam ntxaib digital rov ua dua tag nrho cov kab extrusion zoo, ua kom cov kev sim ua kom zoo dua yam tsis muaj kev cuam tshuam ntau lawm. Kev kawm tshuab algorithms txheeb xyuas qhov sib txawv me me ntawm cov txheej txheem sib txawv thiab cov khoom zoo uas txiav txim siab cov qauv tsis nco qab.
Cov lus nug nquag
Dab tsi txiav txim siab qhov zoo tshaj plaws ntsia hlau ceev rau txheej txheem extruding?
Cov khoom siv viscosity, xav tau lub sijhawm nyob, thiab thermal rhiab heev tsav ntsia hlau ceev xaiv. Cov ntaub ntawv viscosity tsawg yuav tsum muaj kev nrawm dua los tsim kom muaj cov shear txaus rau cua sov, thaum cov ntaub ntawv muaj kuab heev xav tau qeeb qeeb kom tsis txhob muaj kev sib zog ntau dhau. Thaum tshav kub kub- cov ntsiab lus rhiab heev tau txais txiaj ntsig los ntawm kev ua kom nrawm dua kom txo tau lub sijhawm nyob, thaum cov khoom siv tshuaj lom neeg xav tau ntev dua. Feem ntau qhov sib txawv ntawm 20-150 rpm rau plastics compounding thiab 100-600 rpm rau kev ua zaub mov.
Yuav ua li cas compression piv cuam tshuam rau extrusion kev ua tau zoo?
Compression ratio piv pub channel qhov tob rau metering channel qhov tob. Kev sib piv siab dua ua rau muaj kev sib zog ntau dua thiab kev sib xyaw ua ke tab sis ua kom muaj zog tsav torque. Crystalline polymers zoo li polyethylene siv compression ratios ntawm 2.5-4.0 kom densify hmoov txau thiab yaj zoo. Amorphous cov ntaub ntawv zoo li polystyrene xav tau tsuas yog 1.5-2.5 txij li thaum lawv maj mam soften yam tsis muaj discrete melting cov ntsiab lus. Qhov sib piv tsis raug ua rau tsis zoo melting, shear cua sov ntau dhau, lossis tsis txaus siab tsim.
Vim li cas qee daim ntawv thov yuav tsum tau twin screws es tsis txhob siv ib lub screws?
Twin ntsia hlau tshuab muab kev sib xyaw ua ke zoo tshaj plaws rau ntau- cov qauv tsim, tuav cov hmoov thiab pellets ntau dua, thiab tso cai rau cov txheej txheem tswj tau zoo dua los ntawm cov qauv tsim qauv. Cov khoom siv nrog cov khoom ntxiv saum toj 30% kev thauj khoom, noo noo- cov khoom siv hluav taws xob xav tau qhov cua, lossis cov tshuab siv hluav taws xob xav tau kev tswj xyuas qhov kub thiab txias tau txais txiaj ntsig los ntawm lub peev xwm ntxaib ntsia hlau. Ib leeg ntsia hlau tseem pheej yig dua rau kev yooj yim melting thiab siv cov ntaub ntawv homogeneous.
Dab tsi ua rau tuag o thiab nws tswj tau li cas?
Viscoelastic cov ntaub ntawv khaws cov khoom siv hluav taws xob thaum khiav los ntawm kev txwv tuag. Thaum tawm mus, khaws cia lub zog tso tawm thiab cov khoom nthuav dav perpendicular mus rau ntws kev taw qhia. Cov nyhuv nce nrog polymer molecular hnyav, extrusion ceev, thiab tuag av ntev. Cov neeg tsim khoom tuag tau them nyiaj los ntawm kev ua qhov qhib me dua qhov ntev ntawm lub hom phiaj -feem ntau 10-20% rau cov khoom siv thermoplastics. Tom qab tuag txias thiab nqus cov rog tuaj yeem txo qhov nthuav dav.
Xaus
Ntsia hlau-raws li extrusion sawv ua ib qho ntawm cov txheej txheem tsim khoom siv ntau yam, hloov cov khoom sib txawv rau hauv cov khoom tiav los ntawm kev tswj cov tshuab thiab thermal zog. Cov txheej txheem extruding spans los ntawm ib qho yooj yim ib tug ntsia hlau plastics kab rau sophisticated ntxaib ntsia hlau kws tshuab, txhua optimized rau tej yam khoom coj cwj pwm thiab cov khoom yuav tsum tau. Kev nkag siab yuav ua li cas ntsia hlau geometry, qhov kub thiab txias profiles, thiab kev txhim kho siab sib cuam tshuam ua rau cov txheej txheem engineers ua tiav cov txiaj ntsig zoo ib yam txawm tias tsim cov khoom siv dav hlau txhuas, cov yeeb nkab yas, noj tshais cereal, lossis tswj tau - tso tshuaj. Raws li kev suav cov cuab yeej thiab cov thev naus laus zis thev naus laus zis ua ntej, cov txheej txheem extruding txuas ntxiv mus rau kev ua haujlwm zoo dua, kev tswj kom zoo dua qub, thiab txo qhov cuam tshuam ib puag ncig thaum tuav lub hauv paus ntsiab lus: rotating screws hloov cov ntaub ntawv los ntawm shear thiab tshav kub rau hauv cov duab zoo.