1. Tus nqi shrinkage
Daim ntawv thiab kev suav ntawm thermoplastic molding shrinkage yog raws li tau hais los saum toj no. Cov yam ntxwv uas cuam tshuam rau molding shrinkage ntawm thermoplastics yog raws li nram no:
1. Cov hom yas Thaum lub sij hawm molding txheej txheem ntawm thermoplastic plastics, vim muaj tej yam xws li ntim hloov los ntawm crystallization, muaj zog nyob rau hauv kev nyuaj siab, loj residual kev nyuaj siab khov nyob rau hauv cov yas qhov chaw, muaj zog molecular orientation, thiab lwm yam., lub shrinkage tus nqi yog qis dua li. ntawm thermosetting plastics. Loj, dav shrinkage ntau, pom tseeb directionality, thiab tom qab molding.
2. Cov yam ntxwv ntawm cov khoom yas thaum molding, cov khoom molten hu rau saum npoo ntawm cov kab noj hniav thiab cov txheej txheej sab nraud yog txias tam sim ntawd los ua ib lub plhaub uas tsis muaj zog. Vim yog cov thermal conductivity tsis zoo ntawm cov yas, cov txheej txheej hauv cov yas ua kom txias maj mam ua rau cov txheej txheem siab ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom. Yog li ntawd, cov uas muaj phab ntsa tuab, txias txias, thiab cov txheej tuab tuab tuab yuav txo qis dua. Tsis tas li ntawd, lub xub ntiag los yog tsis muaj cov ntawv ntxig thiab qhov kev teeb tsa thiab qhov ntau ntawm cov khoom ntxig ncaj qha cuam tshuam rau cov khoom ntws, kev faib tawm ceev thiab shrinkage tsis kam. Yog li ntawd, cov yam ntxwv ntawm cov khoom yas muaj kev cuam tshuam ntau dua rau qhov loj me me thiab kev taw qhia.
3. Cov yam ntxwv xws li daim ntawv, qhov loj me, thiab kev faib tawm ntawm cov khoom siv nkag ncaj qha cuam tshuam rau cov khoom ntws ntws, kev faib tawm ceev, kev tuav tuav thiab pub mis, thiab lub sijhawm molding. Direct feed inlets thiab feed inlets with large cross-sections (tshwj xeeb yog cov uas muaj cov tuab tuab) muaj me me shrinkage tab sis ntau dua directionality, thaum pub inlets nrog wider thiab luv lengths muaj tsawg directivity. Cov neeg nyob ze rau qhov pub nkag los yog sib npaug rau cov kev taw qhia ntawm cov khoom ntws yuav qis dua.
4. molding tej yam kev mob: pwm kub yog siab, cov khoom molten txias maj mam, muaj siab ceev, thiab shrinks heev. Tshwj xeeb tshaj yog rau cov ntaub ntawv crystalline, lub shrinkage yog ntau dua vim crystallinity siab thiab loj ntim hloov. Lub puab tsaig ntsuas kub kuj cuam tshuam nrog sab hauv thiab sab nraud txias thiab txawv txav ntawm cov yas, uas cuam tshuam nrog txhua ntu. Tsis tas li ntawd, qhov tuav lub siab thiab lub sij hawm kuj muaj kev cuam tshuam ntau dua rau kev shrinkage. Yog hais tias lub siab yog siab thiab lub sij hawm ntev, lub shrinkage yuav me me tab sis kev taw qhia.
Kev txhaj tshuaj molding siab yog siab, viscosity sib txawv ntawm cov khoom molten yog me me, shear stress ntawm cov khaubncaws sab nraud povtseg me me, thiab elastic rebound tom qab demoulding yog loj, yog li lub shrinkage yuav tsum tau txo kom tsim nyog. Cov khoom kub yog siab, lub shrinkage yog loj, tab sis lub directionality yog me me. Yog li ntawd, kev kho ntau yam xws li pwm kub, siab, txhaj tshuaj ceev thiab lub sij hawm txias thaum lub sij hawm molding kuj tsim nyog hloov lub shrinkage ntawm yas ib feem.
Thaum tsim pwm, raws li qhov shrinkage ntau yam ntawm ntau yam yas, phab ntsa tuab thiab cov duab ntawm cov yas, qhov loj thiab kev faib tawm ntawm cov khoom noj khoom haus, qhov shrinkage tus nqi ntawm txhua feem ntawm cov yas yog txiav txim siab raws li kev paub, thiab ces cov kab noj hniav loj yog xam. Rau high-precision yas qhov chaw thiab thaum nws tsis yooj yim los tswj tus nqi shrinkage, cov hauv qab no feem ntau haum:
Tsim pwm:
①Teev tus nqi me me rau cov kab uas hla ntawm cov yas thiab qhov loj dua qhov shrinkage rau sab hauv txoj kab uas hla kom tawm hauv chav rau kev kho tom qab kuaj pwm.
② sim cov pwm los txiav txim seb daim ntawv, qhov loj me thiab molding tej yam kev mob ntawm lub tshuab pouring.
③ Cov kev hloov pauv ntawm cov khoom yas uas yuav tsum tau ua tom qab yuav tsum tau txiav txim siab tom qab ua tiav (kev ntsuas yuav tsum tau ua 24 teev tom qab demoulding).
④ Kho cov pwm raws li qhov xwm txheej shrinkage.
⑤ Sim cov pwm dua thiab hloov cov txheej txheem kom tsim nyog los kho me ntsis tus nqi shrinkage kom tau raws li qhov yuav tsum tau muaj ntawm cov khoom yas. duab
2. Liquidity
Liquidity tau muab faib ua peb pawg:
①Good fluidity: PA, PE, PS, PP, CA, poly (4) methylpentene;
② Nruab nrab fluidity polystyrene series resin (xws li ABS, AS), PMMA, POM, polyphenylene ether;
③ Tsis zoo fluidity PC, tawv PVC, polyphenylene ether, polysulfone, polyarylsulfone, fluoroplastics.
1. Lub fluidity ntawm thermoplastic plastics feem ntau tuaj yeem txheeb xyuas los ntawm ntau qhov ntsuas xws li qhov hnyav molecular, yaj Performance index, Archimedean kauv ntws ntev, pom meej viscosity thiab ntws piv (ntev ntev / yas ntu phab ntsa thickness).
Me me molecular hnyav, dav molecular hnyav tis, tsis zoo molecular qauv tsis tu ncua, siab yaj Performance index, ntev kauv ntws ntev, me me viscosity, thiab loj txaus sib piv muaj fluidity zoo. Rau cov yas uas muaj tib lub npe khoom, koj yuav tsum xyuas cov lus qhia los txiav txim seb qhov fluidity puas haum. Rau kev txhaj tshuaj molding.
2. Lub fluidity ntawm ntau yam yas kuj hloov vim muaj ntau yam molding yam. Lub ntsiab influencing yam yog raws li nram no:
① Qhov kub ntawm cov khoom kub, qhov ntau dua qhov fluidity, tab sis cov yas sib txawv kuj muaj qhov sib txawv, PS (tshwj xeeb tshaj yog cuam tshuam-resistant thiab siab MFR tus nqi), PP, PA, PMMA, hloov polystyrene (xws li ABS, AS) fluidity ntawm plastics xws li , PC, thiab CA hloov tau zoo heev nrog kub. Rau PE thiab POM, qhov kub nce lossis txo qis muaj feem cuam tshuam rau lawv cov dej ntws. Yog li ntawd, tus qub yuav tsum tau kho qhov kub thiab txias los tswj fluidity thaum molding.
② Raws li lub siab ntawm kev txhaj tshuaj molding nce, cov khoom molten yuav raug shearing ntau dua thiab fluidity kuj yuav nce. Tshwj xeeb tshaj yog PE thiab POM yog cov rhiab heev, yog li kev txhaj tshuaj molding siab yuav tsum tau kho thaum lub sij hawm molding los tswj fluidity.
③ Daim ntawv, qhov loj, layout ntawm pwm qauv pouring system, txias system tsim, molten cov ntaub ntawv txaus tsis kam (xws li nto tiav, pub channel seem thickness, kab noj hniav zoo, tso qhov system) thiab lwm yam ncaj qha cuam tshuam cov ndlwg ntawm molten khoom nyob rau hauv lub kab noj hniav Qhov tseeb fluidity nyob rau hauv lub yaj yuav txo yog hais tias qhov kub ntawm cov khoom molten yog txo qis thiab cov fluidity kuj yog nce.
Thaum tsim cov pwm, cov qauv tsim nyog yuav tsum raug xaiv raws li qhov fluidity ntawm cov yas siv. Thaum lub sij hawm molding, yam xws li cov khoom kub, pwm kub, txhaj tshuaj siab, thiab txhaj tshuaj ceev kuj tuaj yeem tswj tau kom tsim nyog kho qhov xwm txheej kom tau raws li cov kev xav tau molding.
3. Crystallinity
Thermoplastic plastics tuaj yeem muab faib ua ob pawg: crystalline plastics thiab amorphous (tseem hu ua amorphous) plastics raws li qhov tseeb tias lawv tsis crystallize thaum condensed.
Lub npe hu ua crystallization tshwm sim yog tias thaum cov yas hloov los ntawm lub xeev molten mus rau lub xeev condensed, cov molecules txav ntawm nws tus kheej thiab muaj kev cuam tshuam tag nrho, thiab cov molecules tsis txav mus los ntawm kev ywj pheej thiab nyob rau hauv ib qho chaw ruaj me ntsis, thiab muaj kev nyiam rau. cov molecules yuav tsum tau teem rau hauv ib tug tsis tu ncua qauv. tshwm sim.
Cov qauv zoo li qhov txawv ntawm ob hom yas no nyob ntawm qhov pom ntawm cov yas tuab tuab. Feem ntau, cov ntaub ntawv crystalline yog opaque lossis translucent (xws li POM, thiab lwm yam), thiab cov ntaub ntawv amorphous yog pob tshab (xws li PMMA, thiab lwm yam).
Txawm li cas los xij, muaj kev zam. Piv txwv li, poly (4) methylpentene yog cov yas crystalline tab sis muaj cov pob tshab siab, thiab ABS yog cov khoom siv amorphous tab sis tsis pob tshab.
Thaum tsim cov pwm thiab xaiv cov tshuab txhaj tshuaj molding, yuav tsum tau them nyiaj rau cov cai hauv qab no thiab kev ceev faj rau cov yas crystalline:
① Nws yuav tsum muaj cua sov ntau los ua kom cov khoom kub nce mus rau qhov kub thiab txias, yog li cov khoom siv nrog cov yas yas loj yuav tsum tau siv.
② Cov cua kub ntau yog tso tawm thaum lub caij txias thiab rov qab los, yog li nws yuav tsum tau txias tag nrho.
③ Qhov sib txawv ntawm lub ntiajteb txawj nqus ntawm lub xeev molten thiab lub xeev cov khoom yog loj, uas ua rau cov molding loj shrinkage thiab nquag mus shrinkage thiab pores.
④ Cov cua txias ceev, tsis tshua muaj crystallinity, me me shrinkage thiab siab transparency. Lub degree ntawm crystallinity yog txuam nrog cov phab ntsa thickness ntawm cov yas. Phab ntsa thickness txhais tau tias qeeb qeeb qeeb, crystallinity siab dua, shrinkage ntau dua, thiab zoo dua lub cev. Yog li ntawd, cov pwm kub ntawm cov ntaub ntawv crystalline yuav tsum tau tswj raws li qhov xav tau.
⑤ Qhov tseem ceeb anisotropy thiab kev ntxhov siab sab hauv. Uncrystallized molecules tom qab demoulding zoo li mus txuas ntxiv mus rau crystallize, nyob rau hauv lub xeev ntawm lub zog tsis txaus, thiab nws yog feem ntau deformation thiab warping.
⑥ Lub crystallization kub ntau yog nqaim, thiab nws yog ib qho yooj yim rau unmelted cov ntaub ntawv yuav tsum tau txhaj rau hauv pwm los yog qhov chaw nres nkoj pub yuav tsum tau thaiv.
4. Thaum tshav kub kub-sensitive plastics thiab yooj yim hydrolyzable plastics
1. Thermal rhiab heev txhais tau hais tias ib co plastics yog rhiab heev rau cua sov. Thaum rhuab ntawm qhov kub thiab txias rau lub sijhawm ntev los yog ntu ntu ntawm qhov qhib qhib me me, lossis cov nyhuv shearing loj, qhov kub ntawm cov khoom nce ntxiv thiab nws muaj feem cuam tshuam rau kev tawg, degradation, thiab decomposition. Hom kev nyiam no Cov yas uas muaj cov khoom tshwj xeeb hu ua cov yas uas muaj cua sov.
Xws li tawv PVC, polyvinylidene chloride, yas acetate copolymer, POM, polychlorotrifluoroethylene, thiab lwm yam. Thaum tshav kub-rhiab plastics decompose, lawv tsim monomers, gases, khib nyiab thiab lwm yam by-products. Tshwj xeeb, qee cov roj decomposition ua rau khaus, corrosive lossis lom rau tib neeg lub cev, khoom siv thiab pwm.
Yog li ntawd, yuav tsum tau them nyiaj mloog mus rau pwm tsim, txhaj tshuaj molding tshuab xaiv thiab molding. Yuav tsum xaiv lub tshuab txhaj tshuaj molding tshuab. Qhov hla ntu ntawm cov txheej txheem pouring yuav tsum loj. Cov pwm thiab lub thoob yuav tsum yog chromium-plated. Yuav tsum tsis muaj kaum lag luam khoom. Lub molding kub thiab cov ntsiab lus yas yuav tsum nruj me ntsis tswj. Ntxiv stabilizers kom tsis muaj zog nws cov khoom cua sov-rhiab heev.
2. Txawm tias qee cov yas (xws li PC) muaj cov dej noo me me, lawv yuav decompose nyob rau hauv qhov kub thiab txias. Cov cuab yeej no hu ua hydrolyzability, thiab nws yuav tsum tau rhuab thiab qhuav ua ntej.
5. Kev ntxhov siab tawg thiab tawg tawg
1. Qee cov yas yog rhiab heev rau kev ntxhov siab. Lawv yooj yim rau kev ntxhov siab sab hauv thaum molding thiab yog nkig thiab yooj yim tawg. Cov khoom yas yuav tawg nyob rau hauv qhov kev txiav txim ntawm sab nraud quab yuam los yog hnyav.
Vim li no, ntxiv rau ntxiv cov khoom siv ntxiv rau cov khoom siv raw los txhim kho kev sib tsoo, kev saib xyuas yuav tsum tau them rau ziab cov ntaub ntawv raw thiab xaiv tsim nyog ntawm molding tej yam kev mob kom txo tau cov kev ntxhov siab nyob rau hauv thiab ua kom tawg tsis kam. Yuav tsum xaiv cov yas zoo ib feem, thiab cov ntawv ntxig thiab lwm yam kev ntsuas yuav tsum tsis txhob muab ntsia kom txo qis kev ntxhov siab.
Thaum tsim pwm, qhov demoulding txoj kab nqes yuav tsum tau nce, qhov tsim nyog pub nkag thiab ejection mechanism yuav tsum raug xaiv, thiab cov khoom kub, pwm kub, txhaj tshuaj siab thiab txias lub sij hawm yuav tsum tau kho kom tsim nyog thaum molding kom tsis txhob demoulding thaum cov yas yog txias heev thiab nkig. , tom qab molding, cov khoom yas yuav tsum tau ua tiav tom qab kev txhim kho cov kab nrib pleb, tshem tawm cov kev ntxhov siab sab hauv thiab txwv tsis pub sib cuag nrog cov kuab tshuaj.
2. Thaum lub polymer yaj nrog ib tug tej yam melt flow rate ntau tshaj ib tug tej yam nqi thaum dhau los ntawm lub nozzle qhov ntawm qhov kub thiab txias, pom tseeb transverse tawg yuav tshwm sim nyob rau hauv lub melt nto, uas yog hu ua melt rupture, uas yuav ua rau lub cev puas tsuaj. cov khoom ntawm cov khoom yas.
Yog li ntawd, thaum xaiv cov polymers nrog siab yaj ntws tus nqi, qhov cross-section ntawm nozzle, khiav, thiab pub inlet yuav tsum tau nce, qhov txhaj tshuaj ceev yuav tsum tau txo, thiab cov khoom kub yuav tsum tau nce.
6. Kev ua haujlwm kub thiab txias txias
1. Ntau yam yas muaj qhov sib txawv thermal xws li cov cua sov tshwj xeeb, thermal conductivity, thiab kub distortion kub. Cov ntaub ntawv yas uas muaj cov cua kub tshwj xeeb yuav tsum muaj cua sov ntau, yog li yuav tsum xaiv lub tshuab txhaj tshuaj molding nrog lub peev xwm loj ntawm plasticizing. Cov yas uas muaj qhov kub thiab txias ntawm qhov kub thiab txias tuaj yeem muaj lub sijhawm txias txias thiab thaum ntxov demoulding, tab sis txias deformation yuav tsum tau tiv thaiv tom qab demoulding.
Cov yas uas muaj cov thermal conductivity tsawg muaj qhov ua kom txias qeeb (xws li ionic polymers, thiab lwm yam, uas muaj qhov txias txias heev), yog li lawv yuav tsum tau txias tag nrho thiab cov pwm txias yuav tsum tau txhim kho. Kub khiav pwm yog tsim rau cov yas uas tsis tshua muaj cua sov thiab siab thermal conductivity. Cov yas uas muaj cov cua sov tshwj xeeb, tsis tshua muaj thermal conductivity, tsis tshua muaj thermal deformation kub, thiab qis qis qis tsis haum rau kev kub ceev molding. Lub tshuab txhaj tshuaj molding tsim nyog yuav tsum tau xaiv thiab pwm txias yuav tsum tau ntxiv dag zog.
2. Ntau yam plastics yuav tsum muaj qhov tsim nyog txias raws li lawv cov yam ntxwv thiab cov duab ntawm cov khoom yas. Yog li ntawd, cov pwm yuav tsum tau nruab nrog lub cua sov thiab cua txias system raws li molding yuav tsum tau kom muaj ib tug tej yam pwm kub. Thaum cov khoom kub nce pwm kub, nws yuav tsum tau txias kom tsis txhob deformation ntawm cov yas tom qab demoulding, luv lub voj voog molding, thiab txo cov crystallinity.
Thaum cov khoom pov tseg ntawm cov yas tsis txaus los khaws cov pwm ntawm qhov kub thiab txias, cov pwm yuav tsum tau nruab nrog lub tshuab cua sov kom cov pwm ntawm qhov kub thiab txias kom tswj tau qhov cua txias, xyuas kom muaj fluidity, txhim kho cov khoom ntim lossis tswj. qhov txias txias ntawm cov yas ib feem. Tiv thaiv kom tsis sib xws ntawm cov yas tuab tuab hauv thiab sab nraud thiab ua kom muaj crystallinity, thiab lwm yam.
Rau cov neeg uas muaj fluidity zoo, qhov loj molding cheeb tsam thiab cov khoom tsis sib xws, cua sov los yog txias yuav tsum tau siv los hloov los yog ob qho tib si hauv zos cua sov thiab cua txias yuav siv tau nyob ntawm seb cov molding tej yam kev mob ntawm cov yas qhov chaw. Rau lub hom phiaj no, cov pwm yuav tsum tau nruab nrog cov cua txias los yog cua sov.
7. Hygroscopicity
Vim hais tias muaj ntau yam additives nyob rau hauv plastics, lawv muaj ntau theem ntawm affinity rau ya raws. Yog li ntawd, cov yas tuaj yeem muab faib ua ob hom: cov uas nqus dej noo, cov uas ua rau cov dej noo, thiab cov uas tsis nqus dej thiab tsis yooj yim rau cov dej noo. Cov dej noo nyob rau hauv cov khoom yuav tsum tau tswj nyob rau hauv qhov chaw tso cai. Txwv tsis pub, cov dej yuav tig mus rau hauv cov pa roj lossis hydrolyze nyob rau hauv qhov kub thiab txias, ua rau cov resin ua npuas dej, txo cov dej ntws, thiab muaj qhov tsis zoo thiab cov khoom siv kho tshuab.
Yog li ntawd, hygroscopic plastics yuav tsum tau preheated siv cov cua kub kom tsim nyog thiab cov lus qhia tshwj xeeb raws li qhov yuav tsum tau ua kom tsis txhob rov nqus dej noo thaum siv.
