Extruder Ntsia Hlau

Cov ntsia hlau yog lub plawv ntawm lub extruder thiab ib qho tseem ceeb ntawm cov extruder. Qhov kev ua tau zoo ntawm cov ntsia hlau txiav txim siab cov khoom tsim tau, plasticizing zoo, dispersion ntawm fillers, yaj kub, zog noj, thiab lwm yam ntawm extruder. Nws yog qhov tseem ceeb tshaj plaws ntawm cov extruder, uas tuaj yeem cuam tshuam ncaj qha rau daim ntawv thov ntau thiab kev ua haujlwm ntawm extruder. Kev sib hloov ntawm cov ntsia hlau exerts siab heev ntawm cov yas, kom cov yas txav tau, nias, thiab tau txais qee qhov cua sov los ntawm kev sib txhuam hauv lub thoob. Cov yas yog tov thiab plasticized thaum lub sij hawm txav hauv lub thoob. Thaum cov viscous yaj yog extruded thiab ntws los ntawm qhov tuag, nws tau txais cov duab xav tau thiab tsim. Zoo li lub thoob, cov ntsia hlau tseem ua los ntawm cov khoom siv muaj zog, kub-resistant thiab corrosion-resistant alloys.
Vim muaj ntau hom yas, lawv cov khoom kuj txawv. Yog li ntawd, hauv kev ua haujlwm tiag tiag, txhawm rau hloov kho cov kev xav tau ntawm cov yas sib txawv, yuav tsum muaj ntau hom screws, thiab cov qauv kuj txawv. Yog li ntawd cov yas tuaj yeem thauj tau, extruded, tov thiab plasticized nrog kev ua haujlwm zoo tshaj plaws.
Cov yam ntxwv tseem ceeb uas sawv cev rau cov yam ntxwv ntawm cov ntsia hlau muaj xws li cov hauv qab no: txoj kab uas hla, nam piv, compression piv, suab, zawj qhov tob, helix lub kaum sab xis, tshem tawm ntawm cov ntsia hlau thiab lub thoob, thiab lwm yam.
Feem ntau cov ntsia hlau taub D yog li 45 ~ 150 hli. Raws li txoj kab uas hla ntawm cov ntsia hlau nce, lub peev xwm ua tiav ntawm extruder kuj nce raws li, thiab cov khoom tsim tau ntawm extruder yog proportional rau lub square ntawm lub taub hau ntsia hlau D. Qhov piv ntawm qhov ntev ntawm qhov ua hauj lwm ntawm cov ntsia hlau mus rau txoj kab uas hla ( abbreviated li nam piv, qhia li L/D) feem ntau yog 18 ~ 25. Lub L / D loj tuaj yeem txhim kho qhov kub thiab txias ntawm cov khoom siv, pab txhawb kev sib xyaw thiab kev sib xyaw ntawm cov yas, thiab txo cov dej xau thiab rov qab. Txhim kho lub peev xwm ntau lawm ntawm extruder. Cov ntsia hlau nrog lub loj L / D muaj zog yoog raws thiab tuaj yeem siv rau extrusion ntawm ntau yam yas; tab sis thaum L/D loj dhau lawm, cov yas yuav raug cua sov rau lub sij hawm ntev thiab degraded. Nyob rau tib lub sijhawm, vim qhov nce ntawm qhov hnyav ntawm cov ntsia hlau, qhov kawg dawb yuav khoov thiab sag, uas yooj yim ua rau khawb ntawm lub thoob thiab cov ntsia hlau, thiab ua rau kev tsim khoom thiab kev ua haujlwm nyuaj; nce lub zog noj ntawm lub extruder. luv luv ib tug ntsia hlau yuav ua rau tsis zoo plasticization ntawm nws.
Ib nrab ntawm qhov sib txawv ntawm lub puab txoj kab uas hla ntawm lub chim thiab txoj kab uas hla ntawm cov ntsia hlau yog hu ua qhov sib txawv δ, uas yuav cuam tshuam rau lub peev xwm ntawm lub extruder. Raws li δ nce, cov khoom tsim tau qis. Nws yog feem ntau tsim nyog los tswj δ ntawm li {{0}}.1 txog 0.6 hli. Thaum δ me me, cov nyhuv shearing ntawm cov khoom yog loj, uas yog conducive rau plasticization. Txawm li cas los xij, yog tias δ ​​me dhau lawm, cov nyhuv shearing muaj zog yuav ua rau cov khoom siv thermomechanical degradation, thiab cov ntsia hlau zoo li yuav tuav los yog rub tawm ntawm phab ntsa. Ntxiv mus, thaum δ me dhau lawm, yuav luag tsis muaj qhov xau thiab rov qab ntawm cov khoom, uas cuam tshuam rau kev sib xyaw ntawm cov yaj mus rau qee yam.
Lub helix lub kaum sab xis Φ yog lub kaum sab xis ntawm cov xov thiab hla ntu ntawm cov ntsia hlau. Raws li Φ nce, lub peev xwm ntau lawm ntawm extruder nce, tab sis cov nyhuv shearing thiab extrusion quab yuam ntawm cov yas txo. Feem ntau, lub kaum sab xis ntawm lub kaum sab xis yog nyob nruab nrab ntawm 10 degree thiab 30 degree, thiab hloov raws li cov kev taw qhia ntawm cov ntsia hlau ntev. Feem ntau siv cov ntsia hlau equidistant, thiab lub suab sib npaug ntawm txoj kab uas hla. Tus nqi ntawm Φ yog li 17 degree 41′
Qhov ntau dua qhov compression piv, qhov ntau dua qhov extrusion piv tau txais los ntawm cov yas. Thaum cov ntsia hlau zawj yog qhov ntiav, nws tuaj yeem tsim cov shear ntau dua ntawm cov yas, uas muaj txiaj ntsig zoo rau kev hloov hluav taws xob ntawm phab ntsa chim thiab cov khoom siv. Qhov siab dua cov khoom sib xyaw thiab plasticizing efficiency, qhov tsim tau qis dua. Ntawm qhov tsis sib xws, thaum cov ntsia hlau zawj sib sib zog nqus, qhov xwm txheej tsuas yog qhov sib txawv. Yog li ntawd, cov ntsia hlau sib sib zog nqus groove screws yog tsim rau cov ntaub ntawv kub-sensitive (xws li polyvinyl chloride); thaum ntiav cov ntsia hlau groove screws yog tsim rau cov yas uas tsis muaj yaj viscosity thiab siab thermal stability (xws li polyamide).
1. Segmentation ntawm cov ntsia hlau
Thaum cov khoom txav mus rau pem hauv ntej ntawm cov ntsia hlau, nws muaj kev hloov pauv ntawm qhov kub thiab txias, siab, viscosity, thiab lwm yam. Raws li cov yam ntxwv ntawm cov khoom hloov pauv, cov ntsia hlau tuaj yeem muab faib ua ntu pub (pub), ntu compression, thiab seem homogenization.
①, Plastics thiab peb lub xeev ntawm cov yas
Cov yas tau muab faib ua ob pawg: thermosetting thiab thermoplastic. Tom qab thermosetting plastics yog tsim thiab solidified, lawv tsis tuaj yeem rhuab thiab yaj. Txawm li cas los xij, cov khoom tsim los ntawm cov thermoplastics tuaj yeem ua kom sov thiab yaj los ua lwm yam khoom.
Raws li qhov kub thiab txias hloov, cov yas thermoplastic hloov mus rau hauv peb lub xeev: lub xeev iav, lub xeev elastic heev thiab lub xeev khov. Raws li qhov kub thiab txias hloov ntau zaus, peb lub xeev hloov ntau zaus.
ib. Cov yam ntxwv sib txawv ntawm polymer melts nyob rau hauv peb lub xeev:
Glassy xeev - yas tshwm raws li cov khoom nruj; Lub thermal kinetic zog yog me me, lub zog intermolecular yog loj, thiab lub deformation feem ntau yog pab los ntawm daim ntawv cog lus lub kaum sab xis deformation; Lub deformation rov qab sai sai tom qab lub zog sab nraud raug tshem tawm, uas belongs rau cov elastic deformation.
Highly elastic xeev - yas tshwm raws li cov khoom zoo li roj hmab; lub deformation yog pab los ntawm stretching ntawm macromolecular conformation tshwm sim los ntawm kev taw qhia ntawm cov saw ntu, thiab tus nqi deformation yog loj; Lub deformation tuaj yeem rov qab tau tom qab lub zog sab nraud raug tshem tawm tab sis yog nyob ntawm lub sijhawm, uas belongs rau elastic deformation.
Viscous flow state - yas tshwm raws li cov kua nplaum heev; thermal zog ntxiv nkoos tus txheeb ze swb txav ntawm cov saw molecules; Lub deformation yog irreversible, uas belongs rau yas deformation
b. Plastic processing thiab peb lub xeev ntawm yas:
Cov yas tuaj yeem txiav hauv lub xeev iav. Nyob rau hauv lub xeev elastic heev, lawv tuaj yeem ncav cuag, xws li hlau kos duab, raj extrusion, tshuab molding thiab thermoforming. Nyob rau hauv lub viscous flow xeev, nws muaj peev xwm ua tiav los ntawm txheej, rotational molding thiab txhaj tshuaj molding.
Thaum qhov kub siab tshaj qhov dej khov hauv lub xeev, cov yas yuav raug thermal decomposition, thiab thaum kub qis dua lub xeev iav, cov yas yuav nkig. Thaum cov yas kub siab tshaj qhov dej khov los yog qis dua lub xeev iav, cov yas yas thermoplastic zoo li deteriorate thiab raug puas tsuaj loj, yog li ob qhov chaw kub no yuav tsum zam thaum ua lossis siv cov khoom yas.
②, peb-theem ntsia hlau
Plastics muaj nyob rau hauv peb lub cev lub cev nyob rau hauv lub extruder - cov txheej txheem hloov ntawm lub xeev ntawm iav, siab elastic xeev thiab viscous flow xeev, thiab txhua lub xeev muaj cov kev cai sib txawv rau cov qauv ntsia hlau.
c. Yuav kom ua tau raws li cov kev cai ntawm ntau lub xeev, cov ntsia hlau ntawm extruder feem ntau muab faib ua peb ntu:
Kev pub mis L1 (tseem hu ua khoom xa khoom seem)
Melting section L2 (hu ua compression section)
Homogenizing seem L3 (hu ua metering seem)
Qhov no yog qhov feem ntau hu ua peb-theem ntsia hlau. Cov txheej txheem extrusion ntawm cov yas hauv peb ntu no txawv.
Kev ua haujlwm ntawm ntu pub mis yog xa cov khoom siv los ntawm lub hopper mus rau ntu compression. Cov yas feem ntau tseem nyob rau hauv ib lub xeev ruaj khov thaum lub sij hawm txav mus thiab yog ib nrab yaj vim yog cua sov. Qhov ntev ntawm ntu pub mis nws txawv nrog hom yas, thiab tuaj yeem nyob tsis deb ntawm lub hopper mus rau 75% ntawm tag nrho qhov ntev ntawm lub khob hau.
Feem ntau hais lus, extrusion ntawm crystalline polymers yog qhov ntev tshaj plaws, ua raws li tawv amorphous polymers, thiab luv tshaj rau mos amorphous polymers. Txij li thaum ntu pub mis tsis tas yuav tsim compression, qhov ntim ntawm nws cov ntsia hlau zawj tuaj yeem tsis hloov pauv. Qhov loj ntawm lub kaum sab xis helix muaj kev cuam tshuam ntau dua rau kev pub noj muaj peev xwm ntawm ntu no, thiab qhov tseeb cuam tshuam rau kev tsim khoom ntawm extruder. Feem ntau, lub kaum sab xis ntawm cov hmoov hmoov yog li 30 degrees, thiab cov khoom tsim tau yog qhov siab tshaj plaws. Lub kaum sab xis ntawm cov khoom thaiv yuav tsum yog li 15 degrees, thiab lub kaum sab xis ntawm cov ntaub ntawv kheej kheej yuav tsum yog li 17 degrees.