Umgangatho wee-PET preforms
I-Polyethylene terephthalate (PET), eyaziwa ngokuba yi-polyester, sisixhobo seplastiki esisetyenziswa kakhulu. Ukuveliswa kwe Iibhotile zePET inokwahlulwa ibe ziinkqubo ezimbini eziphambili ngokusekelwe kuhlobo lwe-preform: i-injection stretch blow molding (ISBM) kunye ne-extrusion stretch blow molding (ESBM). Phakathi kwezi ndlela zimbini, i-ISBM ixhaphake kakhulu ngenxa yokuba lula ukuyilawula, ukusebenza kakuhle kwemveliso, kunye nesantya esiphantsi sokukrazula. Kwinkqubo yokwenza i-blow-molded iibhotile zobuhle, Iitships zePET zifakwa kuqala kwi-preform. Kufuneka ukuba umlinganiselo wezinto ezisetyenzisiweyo ungabi phezulu kakhulu (ngaphantsi kwe-5%), kwaye ukuphinda kusetyenziswe akufuneki kudlule kabini. Ubunzima be-molecular kunye ne-viscosity akufuneki kube phantsi kakhulu (ubunzima be-molecular 31,000 - 50,000, i-intrinsic viscosity 0.78 - 0.85 cm³/g). NgokoMthetho weSizwe woKhuseleko lokutya, izinto ezisetyenzisiweyo azivumelekanga ukuba zisetyenziswe ekupakisheni ukutya kunye namayeza. Ii-preforms eziveliswa yi-injection molding kufuneka zigcinwe ngaphezulu kweeyure ezingama-24 ngaphambi kokusetyenziswa. Ii-preforms ezingasetyenziswanga emva kokufudumeza kufuneka zigcinwe ngaphezulu kweeyure ezingama-48 ngaphambi kokuba zifudumale kwakhona.
Ixesha lokugcina iibhotile zobuhle akufuneki kudlule iinyanga ezintandathu. Umgangatho wee-preforms uxhomekeke kakhulu kumgangatho wezinto ze-PET. Ke ngoko, kuyimfuneko ukukhetha izinto ezilula ukuzifutha nokuyila, kunye nokuphuhlisa inkqubo efanelekileyo yokwenza i-preform. Uvavanyo lubonisa ukuba ii-preforms ezenziwe ngezinto ezikrwada ezingeniswe kwamanye amazwe kulula ukuzifutha kunezo zenziwe ngezinto ezikrwada zasekhaya ezine-viscosity efanayo. Nangona kunjalo, kwii-preforms zebhetshi efanayo, imihla eyahlukeneyo yemveliso inokufuna iinkqubo ezahlukeneyo zokufutha. Umgangatho wee-preforms umisela ubunzima benkqubo yokufutha. Iimfuno zee-preforms ze Iibhotile zePET kuquka ukuba msulwa, okucacileyo, okungenazingcoli nambala, kunye nobude obufanelekileyo bendawo yokujova kunye nesigqubuthelo esijikelezileyo.
Okokuqala, ubungakanani bepreform ye Iibhotile zePET ibalulekile kwisikhongozeli sokugqibela sokupakisha. Xa kumiselwa ubungakanani bepreform, into yokuqala ekufuneka iqwalaselwe yinjongo iibhotile zobuhleIngaba zezokutya, iziselo, izinto zokuthambisa, okanye ezinye iindawo? Iinjongo ezahlukeneyo zinokufuna iimilo ezahlukeneyo kunye namandla eebhotile zokuthambisa. Ngokuqwalasela ngononophelo iimfuno zomthamo wemveliso, amandla e-preform anokufunyanwa, kwaye imilo efanelekileyo inokukhethwa, efana nesangqa, isikwere, okanye i-oval.
Okwesibini, ububanzi bentamo (okanye umlomo) buyiparameter ebalulekileyo. Xa ulinganisa intamo, qiniseka ukuba umlinganiselo uthe tye ukuze ufumane ubungakanani obuchanekileyo bentamo. Ubungakanani bentamo buchaphazela ngokuthe ngqo ukusebenza kokuzalisa nokuthulula Iibhotile zePETIimveliso ezahlukeneyo zinokufuna ubungakanani beentamo ezahlukeneyo, ngoko ke ukhetho olufanelekileyo lwentamo luyimfuneko xa uyila ibhotile.
Okokugqibela, ubunzima be-preform bubhekisa kubunzima be iibhotile zobuhle, kuquka umzimba kunye nentamo. Ubunzima bunokulinganiswa ngokuchanekileyo ngokubeka ubunzima okanye ngokusebenzisa isikali esijikelezayo. Ukuqinisekiswa kobunzima kunxulumene ngokuthe ngqo namandla kunye nokuqina kwebhotile. Xa kujongwa ubunzima, kuyimfuneko ukulinganisela amandla olwakhiwo lwebhotile kunye nexabiso lezinto ezisetyenzisiweyo ukuqinisekisa ukuba imveliso yokugqibela inamandla aneleyo kwaye iyahlangabezana neemfuno zoqoqosho.
Ngokubanzi, ubungakanani, ububanzi bentamo, kunye nobunzima bepreform ye Iibhotile zePET zizinto ezibalulekileyo ekufuneka ziqwalaselwe kwinqanaba loyilo iibhotile zeplastikiNgokulinganisa ngononophelo nangokukhetha ngokufanelekileyo ezi parameters, kunokwenzeka ukuqinisekisa ukuba ibhotile yokugqibela iyahlangabezana neemfuno zemveliso kunye nemigangatho yoshishino, ibonelela ngokusebenza kakuhle kokupakishwa. Ngexesha lenkqubo yokwenziwa kweebhotile, ingqalelo eqhubekayo kulawulo lwale parameters iya kunceda ukuvelisa iibhotile zeplastiki ezikumgangatho ophezulu.