Kev txhaj tshuaj molding txheej txheem thiab kev ua haujlwm ntawm PA

PA - Polyamide, tseem hu ua nylon, yog lub ntsiab lus dav dav rau cov chav kawm loj ntawm amide hom polymers. Cov feem ntau yog PA6, PA66, thiab PA1010. Tsis ntev los no, nrog kev txhim kho ntawm IT kev lag luam, kev siv hom tshiab ntawm polyamide PA46 tau nce siab heev. Nws yog siv los hloov LCP (liquid crystal polymer) los tsim plug-ins ntawm cov computers. Vim nws cov khoom siv zoo heev, tawv tawv, cuam tshuam tsis kam, hnav tsis kam, nws tus kheej lubrication, nplaim retardancy, rwb thaiv tsev, thiab lwm yam, PA yog dav siv nyob rau hauv ntau yam xws li tsheb, machinery, electronics, instruments, chemical engineering, thiab lwm yam. xws li iav, pulleys, bearings, impellers, bushings, ntim, txhuam, zippers, thiab lwm yam.
PA6, PA66 thiab PA46 yog tag nrho cov aliphatic polyamides, uas yog linear polymers. Lawv cov qauv molecular muaj cov polar amide pawg, yog li lawv muaj crystallinity siab. Kev ua tau zoo ntawm PA cov khoom yog nyob ntawm lawv cov crystalline morphology thiab crystallinity. Cov txheej txheem kev ua haujlwm muaj feem cuam tshuam rau cov siv lead ua morphology thiab crystallinity. Cov kev ua haujlwm sib txawv tuaj yeem ua rau muaj kev hloov pauv crystallization txog li 40 feem pua ​​​​ntawm cov khoom PA, txias txias, siab crystallinity, thiab tsim cov ntaub ntawv loj dua crystalline. Kev nqus dej kuj cuam tshuam rau nws cov crystallinity.
Tsis tas li ntawd, thaum lub sijhawm ua haujlwm ntawm PA, vim yog qhov cuam tshuam ntawm kev ntws thiab shear, qee qhov kev taw qhia tuaj yeem tsim tawm, ua rau anisotropy hauv cov khoom lag luam. Lub zog raws li kev taw qhia kev taw qhia zoo dua li qhov tsis yog kev taw qhia, thiab kev taw qhia kuj yog qhov zoo rau cov txheej txheem crystallization. Qhov no yuav tsum tau xav txog hauv kev tsim pwm.
Kev ua haujlwm ntawm PA
Lub cev ua haujlwm
Tsis muaj ntxhiab tsw, tsis muaj pwm, ib nrab pob tshab lossis pob tshab hauv qhov tsos, milky dawb lossis lub teeb daj, nrog qhov ntom ntom ntawm 1.04-1.36. Thaum kub hnyiab, nws emits ib tug tshwj xeeb protein tsw, thiab nplaim taws yog xiav nrog ib tug daj saum kawg.
Mechanical zog
Zoo rigidity thiab toughness, resistant rau rov qab cuam tshuam thiab kev co, nrog ib tug kev pab cuam kub ntawm -40-100 degree . Nws yog resistant rau kev sib txhuam, hnav, thiab nws tus kheej-lubrication, tab sis muaj tsis zoo creep kuj thiab tsis zoo seem stability. Qhov tsis zoo no tuaj yeem kov yeej los ntawm kev ntxiv cov iav fiber ntau los yog sib xyaw nrog lwm cov ntaub ntawv.
Tshuaj tiv thaiv thiab huab cua tsis kam
Muaj ob peb cov kuab tshuaj organic hauv PA, tab sis lawv cov khoom siv tshuaj muaj txiaj ntsig zoo. Cov kuab tshuaj organic hauv PA yog formic acid thiab phenolic compounds. Qhov sib txawv ntawm inorganic acids, hauv paus, thiab ntsev tuaj yeem ua rau PA o, yaj, lossis hydrolyze. Nyob rau hauv qhov xwm txheej ntawm tsis raug tshav ntuj, nws cov kev laus tiv thaiv yog zoo, tab sis nws muaj hnub nyoog sai, discolors cov khoom, thiab nws cov kev ua tau zoo txo ​​nyob rau hauv tshav kub, lub teeb, thiab hluav taws xob tej yam kev mob.
Kev ua tau zoo
Yooj yim kom nqus dej noo thiab yuav tsum tau qhuav ua ntej sib sau.
Lub melting point yog siab, lub melting txwv yog nqaim, thiab cov ntsiab lus melting yog PA6: 215 degree, PA66: 255 degree, thiab PA46: 290 degree, feem.
PA yaj viscosity muaj qhov kub thiab txias rhiab heev thiab shear rhiab heev, tsawg yaj viscosity, thiab zoo flowability.
PA tsis zoo thermal stability nyob rau hauv nws lub xeev molten thiab nws nquag decomposition ntawm kub kub.
Cov cua txias ntawm cov yaj muaj qhov cuam tshuam loj rau cov qauv thiab cov khoom ntawm cov khoom.
Cov txheej txheem tsim yog nrog los ntawm crystallization, uas ua rau lub siab shrinkage tus nqi.
Kev tsim cov cuab yeej thiab pwm
Kev xaiv cov tshuab txhaj tshuaj molding
Screw thiab chim
Vim nws cov tawv tawv, nws tus kheej lubrication, nyuaj rau kev pub mis, siab shear tshav kub tiam, siab melting point, ceev melting ceev, thiab yooj yim decomposition, PA yog characterized. Cov ntsia hlau yuav tsum muaj compressed pa concentration, muaj zog noj muaj peev xwm, loj tsav tsheb, thiab zoo hnav tsis kam. Yog li, cov txheej txheem plasticizing rau PA txhaj tshuaj molding yog raws li hauv qab no: ntu pub mis ntawm cov ntsia hlau ntev dua, cov ntsia hlau zawj nyob rau hauv qhov chaw pub mis yog tob dua, ntu compression thiab homogenization seem yog luv dua, thiab qhov zawj yog rub ntawm ntu pub. ntawm lub thoob los ua kom lub zog ntawm cov roj lub cev muaj zog. Cov ntsia hlau yog nruab nrog lub nplhaib check zoo.
Shooting nozzle
Vim tias qhov viscosity tsawg thiab zoo fluidity ntawm PA nyob rau hauv lub xeev molten, muaj inevitably residual siab nyob rau hauv lub chim. Yog tias siv lub nozzle qhib, cov yaj yuav ntws tawm ntawm lub nozzle thaum cov khoom raug tshem tawm thaum lub sij hawm qhib pwm (xws li salivation tshwm sim), uas tsis yog tsuas yog cov ntaub ntawv pov tseg tab sis kuj cuam tshuam rau kev tsim khoom. Yog li ntawd, ib tug self-locking nozzle, feem ntau siv raws li lub caij nplooj ntoos hlav koob valve nozzle, yog xav tau.
Cov khoom tsim thiab pwm tsim
Nyob rau ntawm qhov chaw ntawm kev ua kom ntseeg tau qhov kev ua tau zoo ntawm cov khoom, cov phab ntsa thickness yuav tsum tau coj me me li sai tau. Cov khoom tuab dua, qhov ntau dua qhov shrinkage, thiab yog tias lub zog tsis txaus, cov khoom siv ntxiv tuaj yeem ntxiv. Cov khoom muaj qhov shrinkage siab thiab yooj yim rau demould, nrog lub demolding lub kaum sab xis ntawm 40 ′ -1 degree 40 ′.
Khiav thiab Rooj vag
Flow txoj kab uas hla Ф {{0}}mm, nrog lub rooj vag txoj kab uas hla ntawm 2/3-3/4 ntawm phab ntsa thickness. Tab sis tsis tsawg tshaj li 0.8mm. Lub rooj vag me me tuaj yeem ua rau cov yaj mus rau shear thiab overheat, ua rau degradation thiab cuam tshuam cov khoom lag luam.
Ntxig
Lub coefficient ntawm thermal expansion ntawm nylon yog 9-10 lub sij hawm loj dua ntawm cov hlau thiab 4-5 lub sij hawm loj dua li ntawm txhuas. Cov hlau ntxig no cuam tshuam qhov contraction ntawm nylon thiab ua rau muaj kev ntxhov siab loj, uas yuav ua rau tawg. Lub thickness nyob ib ncig ntawm lub insert yuav tsum tsis muaj tsawg tshaj li lub cheeb ntawm lub insert hlau.
Tshem tawm
Lub viscosity ntawm PA yog tsawg, thiab nyob rau hauv high-pressure txhaj tshuaj, nws tuaj yeem sau cov pwm sai. Yog tias cov pa roj tsis tuaj yeem raug tso tawm raws sijhawm, cov khoom lag luam yuav ua rau muaj qhov tsis xws luag xws li npuas thiab hlawv. Cov pwm yuav tsum muaj lub qhov tso tawm los yog qhov, feem ntau yog nyob rau sab nraud ntawm lub rooj vag, nrog ib txoj kab uas hla ntawm Ф 1.5-1mm, nrog qhov tso tawm qhov tob tsawg dua 0.03 hli.
Txoj kev tsim
1. Kev npaj cov khoom siv raw
Vim tias qhov nqus dej noo siab ntawm PA, nws muaj kev cuam tshuam rau cov txheej txheem ua, xws li txo qis hauv yaj viscosity thiab muaj npuas, nyiaj kab, thiab lwm yam ntawm cov khoom. Ntxiv mus, cov khoom siv kho tshuab ntawm cov khoom lag luam tau poob qis. Yog li ntawd, kev kho kom qhuav yuav tsum tau ua ua ntej molding. PA yog nquag oxidation, discoloration, thiab degradation ntawm qhov kub thiab txias, yog li nws yog qhov zoo tshaj plaws los siv lub tshuab nqus tsev kom qhuav. Txawm li cas los xij, nyob rau hauv qhov tsis muaj lub tshuab ziab khaub ncaws qhuav, atmospheric cua kub ziab tuaj yeem siv tau.
Lub tshuab nqus tsev ziab kub yog 85-95 degree , thiab lub sijhawm yog 4-6 teev. Cov cua kub kom qhuav yog 90-100 degree, thiab lub sij hawm yog 8-10 teev. Cov khoom siv PA qhuav yuav tsum tsis txhob tso rau hauv huab cua ntev (tsis pub tshaj 1-3 teev).
Ua kub
Kev xaiv ntawm lub thoob kub yog feem ntau raws li qhov melting point ntawm PA, thiab tseem muaj feem xyuam rau hom kev txhaj tshuaj molding tshuab, cov khoom zoo, thiab qhov loj me. Feem ntau ntawm 220-320 degree, PA6: 220-300 degree ; PA66: 260-320 degree . Vim qhov nqaim ua haujlwm kub ntawm PA, qhov kub ntawm lub tshuab chim yuav tsum tau tswj nruj me ntsis kom tsis txhob degradation ntawm cov khoom molten thiab deterioration ntawm cov khoom.
Kev teeb tsa ntawm lub thoob qhov kub thiab txias muaj qhov cuam tshuam tseem ceeb ntawm plasticization thiab melting ceev ntawm plastics. Qhov nruab nrab qhov kub ntawm lub thoob yog 20-40 degree siab tshaj qhov melting point thiab 20-30 degree qis dua qhov kub decomposition. Sab pem hauv ntej kub yog 5-10 degree qis dua qhov nruab nrab qhov kub thiab txias, thiab sab nraub qaum (feem pub) kub yog 20-50 degree qis dua qhov nruab nrab qhov kub; Kev ua kom txias ntawm qhov chaw noj mov yuav tsum ua haujlwm zoo; Yog hais tias qhov kub thiab txias nyob rau hauv nruab nrab seem yog tsawg heev thiab cov ntsia hlau ceev ceev heev, tej zaum yuav muaj jamming phenomenon. Yog hais tias qhov kub thiab txias nyob rau hauv lub rear seem yog siab dhau lawm, nws yuav cuam tshuam rau lub conveying muaj peev xwm, thiab cov ntsia hlau yuav noj maj mam, muaj feem xyuam rau ntau lawm efficiency.
3. Kev txhaj tshuaj siab
Kev txhaj tshuaj siab tsis tshua muaj txiaj ntsig rau cov khoom siv kho tshuab ntawm PA. Kev xaiv ntawm kev txhaj tshuaj siab feem ntau yog nyob ntawm hom kev txhaj tshuaj molding tshuab, chim kub, cov khoom zoo, qhov loj, pwm qauv, nrog rau cov yam ntxwv xws li kev txhaj tshuaj nrawm, lub sijhawm txhaj tshuaj, thiab tuav lub sijhawm.
4. Kev txhaj tshuaj ceev
Kev xaiv ntawm kev txhaj tshuaj nrawm yog cuam tshuam nrog cov phab ntsa tuab ntawm cov khoom, qhov kub ntawm cov yaj, thiab qhov loj ntawm lub rooj vag. Rau cov khoom siv phab ntsa nyias, qhov kev txhaj tshuaj tuaj yeem nrawm dua, thaum rau cov khoom siv phab ntsa tuab, qhov kev txhaj tshuaj tuaj yeem qeeb dua. Yog tias qhov kub ntawm qhov kub yog siab, qhov kev txhaj tshuaj yuav tsum qeeb dua. Qhov loj ntawm lub rooj vag me me, thiab kev txhaj tshuaj yuav tsum tsis txhob ceev heev. Txwv tsis pub, cov shear ntau dhau tuaj yeem ua rau lub melting kub siab dhau thiab degrade, ua rau cov xim hloov thiab cov khoom siv kho tshuab poob qis. Yog tias qhov kev txhaj tshuaj nrawm dhau, nws tuaj yeem ua rau muaj qhov tsis xws luag xws li npuas thiab charring hauv cov khoom.
Ntsia hlau ceev
Nws yog tsim nyog los siv nruab nrab ceev. Yog tias qhov nrawm nrawm dhau, cov yas yuav degrade vim yog shearing ntau dhau, ua rau cov xim tsis zoo thiab kev ua haujlwm degradation ntawm cov khoom. Yog tias qhov nrawm dhau lawm, nws yuav cuam tshuam rau qhov zoo ntawm cov nplaum nplaum thiab tseem cuam tshuam rau kev tsim khoom vim lub sijhawm ntev yaj nplaum.
Rov qab siab
Nyob rau ntawm qhov chaw ntawm kev ua kom cov khoom zoo, qhov qis dua lub nraub qaum, qhov zoo dua. Siab rov qab siab yuav ua rau lub yaj mus shear ntau dhau thiab overheat thiab degrade.
Pwm kub
Cov pwm kub kub nce qhov hardness, ntom, tensile zog, thiab elastic modulus ntawm cov khoom. Cov pwm kub yog cuam tshuam nrog kev ua haujlwm ntawm cov khoom. Rau cov khoom nyias uas yuav tsum tau ua kom zoo elongation thiab pob tshab, nws yog qhov zoo dua los txo cov pwm kub; Yog tias cov khoom tuab nrog lub zog siab, hnav tsis kam, thiab me me deformation yuav tsum tau, nws yog qhov zoo dua kom muaj pwm ntau dua.
Cov ntsiab lus yog raws li nram no:
Khoom thickness pwm kub: tsawg dua 3 hli 20-40 degree, 3-6 hli 40-60 degree, 6-10 hli 60-90 degree, siab tshaj 10 hli 100 degree pwm kub muaj ib tug tseem ceeb cuam tshuam rau tus nqi shrinkage ntawm cov khoom. Qhov siab dua pwm kub, qhov ntau dua qhov shrinkage tus nqi, thiab vice versa.
Tsim lub voj voog
Nws tsuas yog nyob ntawm phab ntsa thickness ntawm cov khoom. Rau cov khoom siv phab ntsa nyias, lub sijhawm txhaj tshuaj, lub sijhawm tuav lub sijhawm, thiab lub sijhawm txias tuaj yeem luv dua. Rau cov khoom siv phab ntsa tuab, txhawm rau tiv thaiv qhov shrinkage deformation, dents, npuas, thiab lwm yam, lub sijhawm txhaj tshuaj thiab lub sijhawm tuav lub sijhawm yuav tsum ntev dua. Thaum siv cov pwm kub kub, lub sijhawm txias yuav tsum ntev dua.
Tom qab ua tiav cov khoom
Lub molecular orientation ntawm PA thaum lub sij hawm molding txheej txheem thiab crystallization thaum lub sij hawm txias txheej txheem ua rau tej yam kev ntxhov siab nyob rau hauv cov khoom. Thaum yav tom ntej cia lossis siv, qhov loj thiab cov duab ntawm cov khoom yuav hloov. Yog li ntawd, annealing thiab humidification kev kho mob yuav tsum tau.
Annealing
Siv cov khoom uas kub siab tshaj 80 degree los yog siab precision yuav tsum. Tom qab demolding cov khoom, annealing lawv nyob rau hauv roj los yog paraffin. Qhov kub thiab txias yog 10-20 degree siab dua qhov siv kub, thiab lub sij hawm yog 10-60 feeb. (Nyob ntawm qhov tuab ntawm cov khoom)
Humidifying
Rau cov khoom uas tau siv ntev ntev hauv cov dej ntub dej los yog cov tshuaj aqueous, thaum lub sij hawm molding txheej txheem, cov khoom raug tshem tawm thiab muab tso rau hauv boiling dej los yog poov tshuaj acetate aqueous tov rau 1-2 hnub.
Lub sijhawm khaws cia ntawm lub thoob
Thaum lub sij hawm tsim cov txheej txheem, yog tias cov nplaum kub siab tshaj 300 degree, nws yog ib qho tsim nyog kom tsis txhob yaj nyob rau hauv lub thoob rau ntev (20 feeb), txwv tsis pub nws yuav overheat thiab decompose, ua rau cov khoom tawg los yog nkig. Yog tias yuav tsum tau kaw ib ntus rau ntau tshaj 20 feeb, qhov ntsuas kub tuaj yeem txo mus rau 200 degree. Thaum kaw lub sijhawm ntev, nws yog qhov yuav tsum tau siv cov khoom siv polymer nrog cov viscosity siab dua los ntxuav lub tshuab chim, uas tuaj yeem ntxuav nrog HDPE lossis PP.