Pulasitiki Extrusion Screw Design ndi Mitundu ya Extrusion Process

Plastics extrusion ndi njira yopangira zinthu zambiri momwe pulasitiki yaiwisi imasungunuka ndikupangidwa kukhala mbiri yopitilira.Extrusion imapanga zinthu monga chitoliro/machubu, zotchingira nyengo, mipanda, njanji zapansi, mafelemu a zenera, mafilimu apulasitiki ndi ma sheeting, zokutira za thermoplastic, ndi kutsekereza waya.

Screw Design:

Mapangidwe a screw ndi ofunika pokonza pulasitiki.Ili ndi ntchito zitatu zosiyana: zomwe ndi njira yodyetsera;kusungunuka kofanana ndi kusakanikirana kwa pulasitiki ndipo pamapeto pake kumatulutsa mphamvu yokankhira zinthu zosungunuka kuti zife.Kutalika kwa screw (L) kumatanthauzidwa ku mainchesi ake (D) ngati chiŵerengero cha L/D.Nthawi zambiri, chiŵerengero cha L/D chimagwiritsidwa ntchito ngati 24:1, koma pakusakaniza ndi kutulutsa zambiri, chikhoza kuwonjezeka mpaka 32:1.Pali magawo atatu otheka muutali wa screw mwachitsanzo, malo osungunuka, malo osungunuka.(a) Malo odyetserako chakudya: M'derali, utomoni umayikidwa kuchokera ku hopper kupita mu mbiya, ndipo kuya kwa tchanelo kumakhala kosasintha.(b) Malo osungunuka: Zinthu zapulasitiki zimasungunuka ndipo kuya kwa njira kumachepera pang'ono.Imatchedwanso transition or compression zone.(c) Metering zone: Pulasitiki yosungunuka imasakanizidwa pa kutentha kofanana ndi kupanikizika ndikutumizidwa kudzera mukufa.Kuzama kwa tchanelo ndikokhazikika mdera lonseli.

Mitundu ya Extrusion Process

The extrusion ndondomeko zambiri m'magulu asanu ndi awiri osiyanasiyana malingana ndi ntchito yeniyeni.(a)Mapepala/Filimu ExtrusionMu njira iyi extrusion, zosungunula pulasitiki zakuthupi ndi extruded kudzera lathyathyathya kufa.Mipukutu yozizirira imagwiritsidwa ntchito kudziwa makulidwe a pepala/filimu ndi mawonekedwe ake.Makulidwe a pepala amatha kupezeka mumitundu ya 0,2 mpaka 15 mm.Pepala lopyapyala kapena filimu yazinthu zapulasitiki zitha kupangidwa.Nthawi zambiri, pulasitiki ya polystyrene imagwiritsidwa ntchito ngati zopangira munjira yotulutsa mapepala.(b)Kuwombedwa Mafilimu ExtrusionMufilimu yowombedwa, kufa kumakhala ngati silinda yoyima yokhala ndi mbiri yozungulira.Pulasitiki wosungunuka amakokedwa m'mwamba kuchokera pakufa ndi ma nip rollers.Mpweya woponderezedwawu umagwiritsidwa ntchito kufukiza chubu.Pansi pake, mphete ya air-air imayikidwa.Cholinga cha mphete ya air-air ndikuziziritsa filimuyo pamene ikupita mmwamba.Pakatikati pa kufa, pali mpweya wolowera kumene mpweya woponderezedwa ukhoza kukakamizidwa kulowa pakati pa mbiri yozungulira, ndikupanga kuwira.Chigawo chozungulira chozungulira chikhoza kuwonjezeka nthawi 2-3 za m'mimba mwake.Ma thovuwo amagwa mothandizidwa ndi mbale yogwa.Mipukutuyo imaphwasula thovulo kukhala wosanjikiza kawiri wa filimu yotchedwa layflat.Makulidwe a khoma la filimuyo amatha kuwongoleredwa posintha liwiro la ma rollers a nip.Layflat imatha kuphwanyidwa ngati mpukutu kapena kudula mawonekedwe omwe mukufuna.Mbali ya pansi pa layflat imasindikizidwa ndi kugwiritsa ntchito kutentha, ndi kudula mopitirira mpaka kupanga kutsegula;choncho angagwiritsidwe ntchito kupanga thumba la pulasitiki.Kutalika kwa ufa kumatha kusiyana ndi 1 mpaka 300 centimita. Nthawi zambiri, pulasitiki ya polyurethane imagwiritsidwa ntchito pochita izi.

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(c)Pa Jacketing Extrusion

Izi zimatchedwanso njira yokutira waya.Pochita izi, waya wopanda kanthu amakokedwa pakati pa ufa.Pali mitundu iwiri yosiyana ya zida za extrusion zomwe zimagwiritsidwa ntchito kutikita pa waya iepressure kapena jekete tooling.Ngati kulumikizana kwapamtima kapena kumamatira kumafunika pakati pa waya ndi zokutira, zida zamagetsi zimagwiritsidwa ntchito.Ngati kumatira sikufunidwa, zida za jekete zimagwiritsidwa ntchito.Kwa zida zokakamiza, waya amachotsedwa mkati mwa kufa, komwe amakumana ndi pulasitiki yosungunuka pamphamvu kwambiri.Kwa zida zopangira jekete, waya amapitilira ndipo pulasitiki yosungunuka imapanga chophimba pawaya pambuyo pa kufa.Waya wopanda kanthu amadyetsedwa kudzera mukufayo ndipo samalumikizana mwachindunji ndi pulasitiki yosungunuka mpaka itachoka.Kusiyana kwakukulu pakati pa jekete ndi kukakamiza zida ndi malo a waya polemekeza kufa.

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(d)Tubing ExtrusionPochita izi, pulasitiki yosungunuka imatulutsidwa kudzera mukufa ndipo magawo opanda kanthu amapangidwa ndikuyika mandrel mkati mwa kufa.Chubu chokhala ndi mabowo angapo chimathanso kupangidwa kuti chigwiritsidwe ntchito mwapadera, poyika mandrels angapo pakati pa kufa.(e)CoextrusionCoextrusion ndi njira yowonjezerapo yopangira zigawo zingapo zakuthupi panthawi imodzi.Amagwiritsidwa ntchito kuyika gawo limodzi kapena angapo pamwamba pa zinthu zoyambira kuti apeze zinthu zinazake monga kuyamwa kwa ultraviolet, grip, matte pamwamba, ndikuwonetsa mphamvu, pomwe zida zoyambira ndizoyeneranso ntchito zina, mwachitsanzo kukana mphamvu ndi kapangidwe kake.Itha kugwiritsidwa ntchito panjira iliyonse monga filimu yowombedwa, kubweza, machubu, ma sheet / filimu extrusion.Pochita izi, ma extruders awiri kapena kuposerapo amagwiritsidwa ntchito popereka zinthu zomwe zimaphatikizidwa mukufa kamodzi komwe kumatulutsa zinthu zomwe zimafunikira.The makulidwe wosanjikiza umalamulidwa ndi liwiro ndi kukula kwa extruders munthu kupereka zipangizo.(f)Extrusion zokutiraChophimba cha Extrusion chimagwiritsidwa ntchito kupanga chowonjezera pa pepala, zojambulazo kapena filimu yomwe ilipo.Mwachitsanzo, kupititsa patsogolo madzi kugonjetsedwa ndi pepala polyethylene ❖ kuyanika ntchito.Ntchito zokutira extrusion ndi kulongedza zamadzimadzi, pepala zithunzi, maenvulopu, matumba akalowa kwa feteleza ma CD ndi ma CD mankhwala.Nthawi zambiri, polyethylene ndi polypropylene amagwiritsidwa ntchito.