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.
Izi zimayamba ndi kudyetsa zinthu zapulasitiki (ma pellets, granules, flakes kapena ufa) kuchokera ku hopper kupita ku mbiya ya extruder. Zinthuzo zimasungunuka pang'onopang'ono ndi mphamvu yamakina yomwe imapangidwa ndi zomangira zokhotakhota komanso zotenthetsera zomwe zimakonzedwa motsatira mbiya. Polima wosungunuka ndiye amakakamizika kukhala kufa, komwe kumapangitsa polima kukhala mawonekedwe omwe amauma panthawi yozizirira.
MBIRI
Kutulutsa kwa bomba
Zoyambira zoyambirira za extruder yamakono zidapangidwa kumayambiriro kwa zaka za zana la 19. Mu 1820, Thomas Hancock anapanga mphira "masticator" yopangidwa kuti itengenso zinyalala za rabara, ndipo mu 1836 Edwin Chaffee anapanga makina odzigudubuza awiri osakaniza zowonjezera mu rabala. Thermoplastic extrusion yoyamba inali mu 1935 ndi Paul Troester ndi mkazi wake Ashley Gershoff ku Hamburg, Germany. Patangopita nthawi pang'ono, Roberto Colombo wa LMP adapanga ma screw extruders oyamba ku Italy.
NJIRA
Mu extrusion ya mapulasitiki, yaiwisi pawiri zinthu zambiri mu mawonekedwe a nurdles (mikanda yaying'ono, nthawi zambiri amatchedwa utomoni) amene mphamvu yokoka amadyetsedwa kuchokera pamwamba wokwera hopper mu mbiya ya extruder. Zowonjezera monga ma colorants ndi UV inhibitors (mumtundu wamadzi kapena pellet) amagwiritsidwa ntchito nthawi zambiri ndipo amatha kusakanikirana ndi utomoni asanafike pa hopper. Njirayi imakhala yofanana kwambiri ndi kuumba kwa jekeseni wa pulasitiki kuchokera ku teknoloji ya extruder, ngakhale kuti imasiyana chifukwa nthawi zambiri imakhala yopitilira. Ngakhale kuti pultrusion imatha kupereka mbiri yofananira mopitilira, nthawi zambiri ndi kulimbitsa kowonjezera, izi zimatheka potulutsa chomaliza mukufa m'malo motulutsa polima kusungunuka kudzera mukufa.
Zinthuzo zimalowa pakhosi la chakudya (potsegula pafupi ndi kumbuyo kwa mbiya) ndikukhudzana ndi screw. Zomangira zozungulira (nthawi zambiri zimatembenuza mwachitsanzo 120 rpm) zimakakamiza mikanda yapulasitiki kupita mumgolo wotenthedwa. The kufunika extrusion kutentha kawirikawiri ofanana ndi anapereka kutentha kwa mbiya chifukwa Kutentha viscous ndi zotsatira zina. Munjira zambiri, mawonekedwe otenthetsera amayikidwa mbiya momwe magawo atatu kapena kuposerapo odziyimira pawokha a PID amawonjezera kutentha kwa mbiya kuchokera kumbuyo (komwe pulasitiki imalowa) kutsogolo. Izi zimathandiza kuti mikanda ya pulasitiki isungunuke pang'onopang'ono pamene ikukankhidwa mu mbiya ndikuchepetsa chiopsezo cha kutentha kwambiri komwe kungayambitse kuwonongeka kwa polima.
Kutentha kowonjezereka kumathandizidwa ndi kupanikizika kwakukulu ndi kukangana komwe kumachitika mkati mwa mbiya. M'malo mwake, ngati chingwe cha extrusion chikuyendetsa zida zina mwachangu, zotenthetsera zimatha kuzimitsidwa ndi kutentha kusungunuka kumasungidwa ndi kukakamizidwa ndi kukangana kokha mkati mwa mbiya. M'ma extruder ambiri, mafani ozizira amakhalapo kuti asunge kutentha pansi pamtengo wokhazikika ngati kutentha kwakukulu kwapangidwa. Ngati kuziziritsa kwa mpweya sikukwanira ndiye kuti majekete oziziritsa oponyedwa amagwiritsidwa ntchito.
Pulasitiki extruder kudula pakati kusonyeza zigawo zikuluzikulu
Kutsogolo kwa mbiyayo, pulasitiki yosungunukayo imasiya wonongazo ndikudutsa pa skrini kuti ichotse zowononga zilizonse zomwe zimasungunuka. Zowonetsera zimalimbikitsidwa ndi mbale yophwanyira (chitsulo cholimba chachitsulo chokhala ndi mabowo ambiri obowoledwa) popeza kupanikizika panthawiyi kumatha kupitirira 5,000 psi (34 MPa). Chophimba chophimba / chophwanyira mbale msonkhano umathandizanso kuti pakhale kupanikizika kumbuyo mu mbiya. Kupsyinjika kumbuyo kumafunika kuti yunifolomu isungunuke ndi kusakaniza koyenera kwa polima, ndi kuchuluka kwa mphamvu zomwe zimapangidwira zingathe "kusinthidwa" ndi mitundu yosiyanasiyana ya paketi (chiwerengero cha zowonetsera, kukula kwake kwa waya, ndi zina). Kuphatikizika kwa mbale iyi ndi paketi yotchinga kumachotsanso "kukumbukira kozungulira" kwa pulasitiki yosungunuka ndikupanga m'malo mwake, "longitudinal memory".
Pambuyo podutsa mbale yophwanyira pulasitiki yosungunuka imalowa mukufa. Chovalacho ndi chomwe chimapatsa chomaliza mbiri yake ndipo chiyenera kupangidwa kuti pulasitiki yosungunula isunthike mofanana kuchokera ku cylindrical profile, kupita ku mawonekedwe a malonda. Kuyenda mosagwirizana panthawiyi kumatha kutulutsa chinthu chokhala ndi zotsalira zosafunikira pazigawo zina zomwe zingayambitse kuzizira. Mitundu yosiyanasiyana imatha kupangidwa, yongopitilira mbiri.
Chogulitsacho chiyenera tsopano kukhazikika ndipo izi nthawi zambiri zimatheka ndi kukoka extrudate kupyolera mu kusamba kwamadzi. Pulasitiki ndi bwino kwambiri matenthedwe insulators choncho ndi ovuta kuziziritsa mwamsanga. Poyerekeza ndi chitsulo, pulasitiki imapangitsa kutentha kwake kutali nthawi 2,000 pang'onopang'ono. Mu chubu kapena chingwe chotulutsa chitoliro, madzi osambira omata amachitidwa ndi vacuum yoyendetsedwa bwino kuti chubu kapena chitoliro chomwe changopangidwa chatsopanocho chisagwe. Kwa zinthu monga mapepala apulasitiki, kuziziritsa kumatheka ndi kukoka kupyolera muzitsulo zoziziritsa. Kwa mafilimu ndi ma sheet owonda kwambiri, kuziziritsa kwa mpweya kumatha kukhala kothandiza ngati gawo loyamba lozizirira, monga momwe amawululira filimuyo.
Zotulutsa pulasitiki zimagwiritsidwanso ntchito kwambiri kukonzanso zinyalala zapulasitiki zobwezerezedwanso kapena zida zina mutatsuka, kusanja ndi/kapena kusakaniza. Zinthuzi nthawi zambiri zimatulutsidwa m'mizere yoyenera kudulidwa mu mkanda kapena pellet stock kuti agwiritse ntchito ngati kalambulabwalo kuti apitilize kukonza.
KUSINTHA KWA SCREW
Pali magawo asanu otheka mu screw thermoplastic. Popeza mawu akuti terminology sali okhazikika m'makampani, mayina osiyanasiyana amatha kutanthauza maderawa. Mitundu yosiyanasiyana ya polima idzakhala ndi zomangira zosiyanasiyana, zina zosaphatikizira madera onse omwe angathe.
A yosavuta pulasitiki extrusion screw
Zomangira za Extruder Kuchokera ku Boston Matthews
Zomangira zambiri zimakhala ndi zigawo zitatu izi:
● Malo odyetserako chakudya (omwe amatchedwanso kuti zone yotumizira zinthu zolimba): chigawochi chimalowetsa utomoni wotuluka, ndipo kuya kwa tchanelo nthawi zambiri kumakhala kofanana m'dera lonselo.
● Malo osungunuka (omwe amatchedwanso transition kapena compression zone): ma polima ambiri amasungunuka m'gawoli, ndipo kuya kwa tchanelo kumachepera pang'ono.
● Metering zone (yomwe imatchedwanso melt conveying zone): chigawochi chimasungunula tinthu tating'ono tomaliza ndikusakanikirana ndi kutentha kofanana ndi kapangidwe kake. Monga malo odyetserako chakudya, kuya kwa tchanelo kumakhala kosalekeza m'dera lonseli.
Kuphatikiza apo, phula lotulutsa mpweya (gawo ziwiri) lili ndi:
● Decompression zone. M'derali, pafupifupi magawo awiri pa atatu pansi pa screw, tchanelo chimafika mozama, zomwe zimachepetsa kupanikizika ndikulola kuti mpweya uliwonse wotsekeka (chinyezi, mpweya, zosungunulira, kapena zosungunulira) zitulutsidwe ndi vacuum.
● Malo oyezera mita yachiwiri. Derali ndi lofanana ndi loyambira metering, koma ndikuzama kwa tchanelo. Zimagwira ntchito kuti zitsitsimutse kusungunuka kuti zitheke kupyolera mu kukana kwa zowonetsera ndi kufa.
Nthawi zambiri utali wa screw umatchulidwa m'mimba mwake ngati chiŵerengero cha L:D. Mwachitsanzo, wononga 6-inch (150 mm) m'mimba mwake pa 24:1 idzakhala mainchesi 144 (12 ft) utali, ndipo pa 32:1 ndi 192 mainchesi (16 ft) utali. Chiŵerengero cha L:D cha 25:1 ndichofala, koma makina ena amapita ku 40:1 kuti asakanize kwambiri ndi kutulutsa zambiri pa screw diameter yomweyi. Zomangira zagawo ziwiri (zotuluka) nthawi zambiri zimakhala 36:1 kuwerengera magawo awiri owonjezera.
Chigawo chilichonse chimakhala ndi thermocouples imodzi kapena zingapo kapena ma RTD pakhoma la mbiya pofuna kuwongolera kutentha. The "kutentha mbiri" mwachitsanzo, kutentha kwa zone aliyense n'kofunika kwambiri kwa khalidwe ndi makhalidwe a extrudate yomaliza.
TYPICAL EXTRUSION MATERIALS
HDPE chitoliro pa extrusion. Zida za HDPE zimachokera ku chotenthetsera, kulowa mufa, kenako kulowa mu thanki yozizira. Chitoliro ichi cha Acu-Power conduit chimalumikizidwa - chakuda mkati ndi jekete yopyapyala yalalanje, kuti iwonetse zingwe zamagetsi.
Chitsanzo zipangizo pulasitiki kuti ntchito extrusion monga koma si zokhazo: polyethylene (PE), polypropylene, acetal, akiliriki, nayiloni (polyamides), polystyrene, polyvinyl kolorayidi (PVC), acrylonitrile butadiene styrene (ABS) ndi polycarbonate.[4] ]
MITUNDU YA KUFA
Pali mitundu yosiyanasiyana yakufa yomwe imagwiritsidwa ntchito popanga mapulasitiki. Ngakhale pangakhale kusiyana kwakukulu pakati pa mitundu yakufa ndi zovuta, zonse zimafa zimalola kuti polima asungunuke mosalekeza, kusiyana ndi kusamalidwa kosalekeza monga kuumba jekeseni.
Kuwombera filimu extrusion
Kuwomba extrusion pulasitiki filimu
Kupanga filimu yapulasitiki pazinthu monga matumba ogula ndi mapepala osalekeza amapindula pogwiritsa ntchito filimu yowombedwa.
Njirayi ndi yofanana ndi njira yowonjezera yowonjezera mpaka imfa. Pali mitundu itatu ikuluikulu yakufa yomwe imagwiritsidwa ntchito pochita izi: annular (kapena crosshead), kangaude, ndi spiral. Annular dies ndiwosavuta kwambiri, ndipo amadalira njira ya polima yosungunuka kuzungulira gawo lonse lakufa musanatuluke kufa; izi zitha kupangitsa kuyenda kosagwirizana. Kangaude amafa zigwirizana chapakati mandrel Ufumuyo mphete yakunja kufa kudzera angapo "miyendo"; pamene kutuluka kumakhala kofanana kwambiri kuposa kufa kwa annular, mizere yambiri yowotcherera imapangidwa yomwe imafooketsa filimuyo. Spiral dies amachotsa nkhani ya mizere yowotcherera ndi kutuluka kwa asymmetrical, koma ndizovuta kwambiri.
Kusungunulako kumazizira pang'ono asanaisiye kufa kuti apereke chubu chofooka cholimba. Kutalika kwa chubuchi kumakulitsidwa mwachangu kudzera mu mpweya, ndipo chubucho chimakokedwa mmwamba ndi zodzigudubuza, kutambasula pulasitiki kumbali zonse zodutsa ndi zojambula. Kujambula ndi kuwomba kumapangitsa kuti filimuyo ikhale yocheperapo kuposa chubu chodumphira, komanso imagwirizanitsa maunyolo a polima momwe amawonera pulasitiki kwambiri. Ngati filimuyo imakokedwa kuposa momwe ikuwombedwa (m'mimba mwake ya chubu yomaliza ili pafupi ndi m'mimba mwake) mamolekyu a polima adzakhala ogwirizana kwambiri ndi njira yojambula, kupanga filimu yomwe ili yolimba kumbali imeneyo, koma yofooka mu njira yodutsa. . Kanema yemwe ali ndi mainchesi okulirapo kuposa m'mimba mwake wotuluka amakhala ndi mphamvu zambiri podutsa, koma mocheperako.
Pankhani ya polyethylene ndi ma polima ena a semi-crystalline, pamene filimuyo imazizira imawala kwambiri pa zomwe zimadziwika kuti chisanu. Pamene filimuyo ikupitiriza kuzizira, imakokedwa kupyolera mumagulu angapo a nip rollers kuti aphwanthike kukhala machubu osayanjanitsika, omwe amatha kuphwanyidwa kapena kudulidwa kukhala mipukutu iwiri kapena kuposerapo.
Mapepala/filimu extrusion
Mapepala/filimu extrusion amagwiritsidwa ntchito kutulutsa mapepala apulasitiki kapena mafilimu omwe ndi okhuthala kwambiri kuti asawombedwe. Pali mitundu iwiri ya ma dies omwe amagwiritsidwa ntchito: mawonekedwe a T ndi chopachika malaya. Cholinga cha izi zimafa ndikuwongoleranso ndikuwongolera kuyenda kwa polima kusungunula kuchokera kumtundu umodzi wozungulira kuchokera ku extruder kupita kumayendedwe opyapyala, osalala. M'mitundu yonse iwiri yakufa imawonetsetsa mosalekeza, kuyenda kofanana kudutsa gawo lonse lakufa. Kuziziritsa kumachitika podulira mipukutu yozizirira (kalendara kapena "kuzizira"). Mu pepala extrusion, masikono izi osati kupereka kuzirala koyenera komanso kudziwa makulidwe pepala ndi pamwamba kapangidwe. Nthawi zambiri co-extrusion imagwiritsidwa ntchito kuyika gawo limodzi kapena angapo pamwamba pa zinthu zoyambira kuti apeze zinthu zinazake monga kuyamwa kwa UV, kapangidwe kake, kukana oxygen permeation, kapena kuwunikira mphamvu.
Njira yodziwika bwino ya post-extrusion ya pepala la pulasitiki ndi thermoforming, pomwe pepala limatenthedwa mpaka lofewa (pulasitiki), ndikupangidwa kudzera mu nkhungu kukhala mawonekedwe atsopano. Pamene vacuum imagwiritsidwa ntchito, nthawi zambiri imatchedwa vacuum kupanga. Kuyang'ana (mwachitsanzo, kuthekera / kupezeka kwa pepala kuti akokedwe ku nkhungu yomwe imatha kusiyanasiyana mozama kuchokera pa mainchesi 1 mpaka 36 nthawi zambiri) ndikofunikira kwambiri ndipo kumakhudza kwambiri nthawi yopangira mapulasitiki ambiri.
Tubing extrusion
Machubu owonjezera, monga mapaipi a PVC, amapangidwa pogwiritsa ntchito kufa kofananira komwe kumagwiritsidwa ntchito potulutsa filimu yowombedwa. Kuponderezedwa kwabwino kungagwiritsidwe ntchito m'mabowo amkati kudzera pa pini, kapena kukakamiza koyipa kungagwiritsidwe ntchito kunja kwake pogwiritsa ntchito vacuum sizer kuti muwonetsetse miyeso yolondola yomaliza. Ma lumens owonjezera kapena mabowo amatha kuyambitsidwa powonjezera ma mandrel oyenera amkati pakufa.
A Boston Matthews Medical Extrusion Line
Machubu amitundu ingapo amapezekanso nthawi zonse m'makampani amagalimoto, ma plumbing & heaters ndi makampani onyamula katundu.
Pa jekete extrusion
Over jacketing extrusion imalola kugwiritsa ntchito pulasitiki wakunja pawaya kapena chingwe chomwe chilipo. Izi ndizomwe zimapangidwira mawaya oteteza.
Pali mitundu iwiri yosiyana ya zida zakufa zomwe zimagwiritsidwa ntchito kupaka waya, chubu (kapena jekete) ndi kukakamiza. Poyika zida za jacket, kusungunuka kwa polima sikukhudza waya wamkati mpaka milomo yakufa isanachitike. Pokanikizira zida, kusungunula kumalumikizana ndi waya wamkati nthawi yayitali isanafike pamilomo yakufa; izi zimachitika pa kuthamanga kwambiri kuti zitsimikizire kumamatira kwabwino kwa kusungunuka. Ngati kulumikizana kwapamtima kapena kumamatira kumafunika pakati pa wosanjikiza watsopano ndi waya womwe ulipo, zida zamagetsi zimagwiritsidwa ntchito. Ngati kumamatira sikufunidwa / kofunikira, zida za jekete zimagwiritsidwa ntchito m'malo mwake.
Coextrusion
Coextrusion ndi kutulutsa kwa zigawo zingapo nthawi imodzi. Mtundu uwu wa extrusion umagwiritsa ntchito ma extruder awiri kapena kuposerapo kuti asungunuke ndikupereka kutulutsa kokhazikika kwa mapulasitiki osiyanasiyana a viscous kumutu umodzi wotulutsa (kufa) womwe udzatulutsa zinthuzo mu mawonekedwe omwe mukufuna. Ukadaulo uwu umagwiritsidwa ntchito pazilizonse zomwe zafotokozedwa pamwambapa (filimu yowombedwa, kubweza, machubu, pepala). Makulidwe osanjikiza amayendetsedwa ndi liwiro wachibale ndi makulidwe a munthu extruders kupereka zipangizo.
5 : 5 Wosanjikiza co-extrusion wa zodzikongoletsera "finya" chubu
Muzochitika zambiri zadziko lapansi, polima imodzi siyingakwaniritse zofunikira zonse za pulogalamuyo. Compound extrusion imalola kuti zinthu zosakanikirana zitulutsidwe, koma coextrusion imasunga zinthu zosiyana monga zigawo zosiyana muzinthu zowonjezera, zomwe zimalola kuyika koyenera kwa zipangizo zomwe zimakhala ndi zinthu zosiyanasiyana monga mpweya wa okosijeni, mphamvu, kuuma, ndi kukana kuvala.
Extrusion zokutira
Chophimba chowonjezera chimagwiritsa ntchito filimu yowombedwa kapena yoponyedwa kuti muphike chowonjezera pa pepala, zojambulazo kapena filimu yomwe ilipo. Mwachitsanzo, njirayi ingagwiritsidwe ntchito kuwongolera mawonekedwe a pepala powapaka ndi polyethylene kuti asamve madzi. Chosanjikiza chowonjezera chingagwiritsidwenso ntchito ngati zomatira kubweretsa zinthu zina ziwiri pamodzi. Tetrapak ndi chitsanzo chamalonda cha njirayi.
COMPOUND EXTRUSIONS
Compounding extrusion ndi njira yomwe imasakaniza ma polima amodzi kapena angapo ndi zowonjezera kuti apereke mankhwala apulasitiki. Zakudyazo zingakhale ma pellets, ufa ndi / kapena zakumwa, koma mankhwalawa nthawi zambiri amakhala amtundu wa pellet, kuti agwiritsidwe ntchito popanga mapulasitiki monga extrusion ndi jekeseni. Monga ndi extrusion chikhalidwe, pali osiyanasiyana makulidwe makina kutengera ntchito ndi throughput ankafuna. Ngakhale ma extruder amodzi kapena awiri angagwiritsidwe ntchito muzowonjezera zachikhalidwe, kufunikira kosakanikirana kokwanira pakuphatikiza kutulutsa kumapangitsa kuti ma twin-screw extruder onse koma ovomerezeka.
MITUNDU YA EXTRUDER
Pali mitundu iwiri ya ma screw extruder: yozungulira komanso yozungulira. Nomenclature iyi imatanthawuza komwe kuli kozungulira kozungulira kofananira ndi kwina. Munjira yozungulira, zomangira zonse zimazungulira molunjika kapena mopingasa; pozungulira, sikona imodzi imazungulira mozungulira pomwe inayo imazungulira motsata wotchi. Zasonyezedwa kuti, chifukwa cha kupatsidwa gawo lalikulu la gawo ndi digiri ya kuphatikizika (intermeshing), kuthamanga kwa axial ndi digiri ya kusanganikirana ndikokwera kwambiri pozungulira mapasa. Komabe, kuthamanga kwachulukidwe kumakhala kokulirapo mu ma extruder ozungulira. Mapangidwe a screw nthawi zambiri amakhala modular chifukwa zinthu zosiyanasiyana zotumizira ndi kusakaniza zimakonzedwa pamiyendo kuti zitheke kukonzanso mwachangu kusintha kwazinthu kapena kusinthidwa kwa zigawo zamtundu uliwonse chifukwa chakuvala kapena kuwonongeka kwa dzimbiri. Kukula kwa makina kumayambira ang'onoang'ono mpaka 12 mm mpaka 380mm
ZABWINO
Ubwino waukulu wa extrusion ndikuti mbiri monga mapaipi amatha kupangidwa kutalika kulikonse. Ngati zinthuzo ndi zotha kusinthasintha mokwanira, mapaipi amatha kupangidwa motalika ngakhale atazungulira pa reel. Ubwino wina ndi extrusion wa mipope ndi Integrated coupler kuphatikizapo mphira chisindikizo.
Nthawi yotumiza: Feb-25-2022
