Muaj ntau yam yuav tsum tau xav txog hauv kev txhaj tshuaj molding txheej txheem

Muaj ntau yam yuav tsum tau xav txog hauv kev txhaj tshuaj molding txheej txheem
1, Daim ntawv thiab kev suav ntawm shrinkage rau thermoplastic molding yog raws li tau hais ua ntej, thiab cov yam ntxwv uas cuam tshuam rau shrinkage ntawm thermoplastic molding yog raws li nram no:
1.1 Plastic Ntau Yam Thaum lub sij hawm molding txheej txheem ntawm thermoplastic plastics, vim muaj cov ntim hloov pauv los ntawm crystallization, muaj zog sab hauv kev ntxhov siab, siab residual kev nyuaj siab khov rau hauv cov yas, thiab muaj zog molecular orientation, lub shrinkage tus nqi yog loj, nrog rau ntau yam shrinkage tus nqi thiab pom tseeb directionality piv rau thermosetting plastics. Tsis tas li ntawd, qhov shrinkage tus nqi tom qab molding, annealing, los yog humidity kho kho yog feem ntau loj dua li cov thermosetting yas.
1.2 Cov yam ntxwv ntawm cov khoom yas: thaum tsim cov khoom yas: thaum cov khoom siv molten tam sim ntawd txias kom tsim cov pob zeb tsawg Vim yog cov neeg txom nyem thermal conductivity ntawm cov yas, sab hauv txheej yas maj mam txias thiab ua cov txheej txheej siab nrog cov pob zeb loj. Yog li cov neeg uas muaj phab ntsa tuab, txias txias, thiab cov txheej tuab tuab tuab zoo li cog lus ntau dua. Tsis tas li ntawd, lub xub ntiag los yog tsis muaj inserts thiab layout thiab kom muaj nuj nqis ntawm inserts ncaj qha cuam tshuam rau cov kev taw qhia ntawm cov ntaub ntawv ntws, ceev tis thiab shrinkage kuj, yog li cov yam ntxwv ntawm yas seem muaj feem xyuam rau qhov loj thiab kev coj ntawm shrinkage.
1.3 daim foos, qhov loj me thiab faib cov khoom noj ncaj qha cuam tshuam cov kev taw qhia, kev faib tawm ntom ntom thiab cov sijhawm ua haujlwm. Qhov chaw noj mov ncaj qha thiab qhov loj hla ntawm qhov chaw noj mov (tshwj xeeb yog cov uas muaj qhov sib txawv tuab) muaj qhov me me tab sis ntau dua kev taw qhia, thaum cov uas muaj luv luv thiab ntev ntawm qhov chaw noj mov muaj me me directionality. Cov neeg uas nyob ze rau qhov pub nkag los yog sib npaug mus rau cov kev taw qhia ntawm cov khoom ntws yuav muaj kev shrinkage ntau dua.
1.4 Moulding tej yam kev mob: pwm kub kub, txias qeeb ntawm cov khoom molten, siab ceev, thiab loj shrinkage, tshwj xeeb tshaj yog rau cov ntaub ntawv crystalline vim siab crystallinity thiab loj ntim hloov, ua rau ntau dua shrinkage. Kev faib khoom ntawm cov pwm kub kuj tseem cuam tshuam nrog sab hauv thiab sab nraud txias thiab qhov tsis zoo ntawm cov yas thiab kev coj ntawm shrinkage hauv txhua feem. Tsis tas li ntawd, kev tswj xyuas lub siab thiab lub sijhawm kuj tseem muaj kev cuam tshuam loj rau kev cog lus, nrog kev kub siab thiab lub sijhawm ntev ua rau me me tab sis kev taw qhia contraction. Kev txhaj tshuaj siab yog siab, qhov sib txawv ntawm qhov sib txawv ntawm cov khoom molten yog me me, lub interlayer shear stress me me, thiab elastic rebound tom qab demolding yog loj, yog li lub shrinkage kuj yuav txo qis me ntsis. Cov khoom kub yog siab, lub shrinkage yog loj, tab sis lub directionality yog me me. Yog li ntawd, kev kho 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 qhov chaw noj mov, qhov shrinkage tus nqi ntawm txhua feem ntawm cov yas yog txiav txim siab raws li kev paub dhau los, thiab ces cov kab noj hniav loj yog xam. Rau cov khoom yas siab thiab thaum nws tsis yooj yim los tswj tus nqi shrinkage, cov txheej txheem hauv qab no feem ntau yuav tsum tau siv los tsim pwm: ① Siv tus nqi qis me me rau lub cheeb ntawm cov yas sab nraud thiab qhov loj me me rau qhov loj me. sab hauv txoj kab uas hla kom tawm hauv chav rau kev kho tom qab kuaj pwm. ② Txiav txim siab daim ntawv, qhov loj me, thiab molding tej yam kev mob ntawm lub pouring system los ntawm kev kuaj pwm. ③ Kev hloov pauv loj ntawm cov khoom yas yuav tsum tau kho tom qab yuav tsum tau txiav txim siab tom qab 24 teev ntawm demolding thaum ntsuas. ④ Kho cov pwm raws li qhov xwm txheej shrinkage. ⑤ Sim cov pwm dua thiab kho cov txheej txheem me ntsis los kho tus nqi shrinkage kom tau raws li qhov yuav tsum tau ua ntawm cov yas.
2, Liquidity
2.1 Lub fluidity ntawm thermoplastics feem ntau tuaj yeem txheeb xyuas los ntawm ntau qhov kev ntsuas xws li qhov hnyav molecular, yaj qhov ntsuas, Archimedes kauv ntws ntev, pom meej viscosity thiab ntws piv (ntev ntev / yas ntu phab ntsa tuab). Nrog me me molecular hnyav, dav molecular hnyav tis, tsis zoo molecular qauv tsis tu ncua, siab yaj Performance index, ntev kauv ntws ntev, tsis tshua muaj viscosity, thiab loj txaus ratio, lub fluidity yog zoo. Rau cov yas nrog tib lub npe khoom, cov lus qhia yuav tsum tau kuaj xyuas seb qhov fluidity puas haum rau kev txhaj tshuaj molding. Raws li qhov yuav tsum tau ua ntawm cov pwm tsim, cov flowability ntawm cov khoom siv feem ntau tuaj yeem muab faib ua peb pawg: ① zoo flowability PA, PE, PS, PP, CA, poly (4) methylene; ② Nruab nrab fluidity polystyrene series resins (xws li ABS, AS), PMMA, POM, polyphenylene ether; ③ Tsis zoo fluidity PC, tawv PVC, polyphenylene ether, polysulfone, polyarylsulfone, fluoroplastics.
2.2 Lub fluidity ntawm ntau yam yas kuj txawv vim muaj ntau yam molding yam, thiab lub ntsiab influencing yam yog raws li nram no:
① Thaum qhov kub ntawm cov khoom yog siab, lub flowability nce, tab sis txawv plastics kuj muaj qhov sib txawv. Lub flowability ntawm cov yas xws li PS (tshwj xeeb tshaj yog cov uas muaj kev cuam tshuam siab thiab MFR tus nqi), PP, PA, PMMA, hloov polystyrene (xws li ABS, AS), PC, CA, thiab lwm yam. nws txawv heev nrog kub. Rau PE thiab POM, qhov nce lossis txo qis hauv qhov kub thiab txias tsis cuam tshuam rau lawv cov dej ntws. Yog li ntawd tus qub yuav tsum tau kho qhov kub thiab txias los tswj lub fluidity thaum molding.
② Thaum qhov kev txhaj tshuaj nce siab, cov khoom siv molten raug rau qhov kev txiav txim siab ntau dua thiab ua rau nws muaj dej ntau dua, tshwj xeeb tshaj yog PE thiab POM rhiab dua. Yog li ntawd, nws raug nquahu kom kho qhov kev txhaj tshuaj siab thaum lub sij hawm molding los tswj cov fluidity.
③ Daim ntawv, qhov loj me, kev teeb tsa, kev tsim qauv txias, thiab cov dej tsis kam ntawm cov khoom molten (xws li nto smoothness, cov khoom siv channel cross-sectional thickness, kab noj hniav, qhov tso pa tawm) ntawm pwm qauv pouring system tag nrho ncaj qha cuam tshuam rau qhov tseeb ntws ntawm molten khoom nyob rau hauv kab noj hniav. Cov yam tseem ceeb uas txhawb qhov txo qhov kub thiab nce qhov dej tsis kam ntawm cov khoom molten yuav txo nws cov dej tsis kam. 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 ntim kom tau raws li qhov xav tau molding.
3, Crystallinity
Thermoplastics tuaj yeem muab faib ua ob pawg: crystalline plastics thiab amorphous (tseem hu ua amorphous) plastics raws li lawv qhov tsis muaj crystallization thaum lub sij hawm condensation. Lub npe hu ua crystallization phenomenon yog hais txog qhov tshwm sim uas cov yas molecules txav ntawm nws tus kheej thiab nyob rau hauv ib qho kev tsis sib haum xeeb los ntawm lub xeev molten mus rau lub xeev condensation, uas ua rau cov molecules nres dawb txav thiab ua raws li ib tug me ntsis taag txoj hauj lwm, nrog ib tug nyiam npaj. cov molecules rau hauv cov qauv tsis tu ncua. Cov qauv zoo li no rau kev paub qhov txawv ntawm ob hom yas no nyob ntawm qhov pom ntawm cov phab ntsa tuab tuab. Feem ntau, cov ntaub ntawv crystalline yog opaque lossis semi pob tshab (xws li POM), thaum cov ntaub ntawv amorphous yog pob tshab (xws li PMMA). Txawm li cas los xij, kuj tseem muaj kev zam, xws li poly (4) methylene, uas yog cov yas crystalline tab sis muaj cov pob tshab siab, thiab ABS, uas 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 Tus nqi ntawm cov cua sov yuav tsum tau nce cov khoom kub rau qhov kub thiab txias yuav tsum tau siv cov khoom siv nrog cov yas yas siab.
② Thaum lub sijhawm ua kom txias thiab rov ua dua tshiab, cov cua kub ntau yog tso tawm, thiab tsim kom muaj cua txias txaus.
③ Qhov sib txawv ntawm lub ntiajteb txawj nqus ntawm lub xeev molten thiab lub xeev cov khoom yog loj, ua rau cov molding loj shrinkage thiab susceptibility rau shrinkage thiab porosity.
④ Cov cua txias ceev, tsis tshua muaj crystallinity, me me shrinkage, thiab siab transparency. Lub crystallinity muaj feem xyuam rau cov phab ntsa tuab ntawm cov khoom yas, uas ua rau kom txias txias, siab crystallinity, shrinkage loj, thiab lub cev zoo. Yog li ntawd, pwm kub yuav tsum tau tswj raws li qhov yuav tsum tau rau cov ntaub ntawv crystalline.
⑤ Qhov tseem ceeb anisotropy thiab siab sab hauv. Cov molecules uas tsis tau crystallized tom qab demolding yuav mus ntxiv crystallize, nyob twj ywm nyob rau hauv lub zog tsis txaus lub xeev, thiab nws yog feem ntau deformation thiab warping.
⑥ Lub crystallization kub ntau yog nqaim, thiab nws yog ib qho yooj yim rau txhaj tshuaj unmelted rau hauv pwm los yog thaiv qhov chaw noj mov.
4, Thermosensitive plastics thiab yooj yim hydrolyzable plastics
4.1 Thermosensitivity yog hais txog qhov nyiam ntawm tej yam yas los hloov xim, degrade, thiab decompose raws li cov khoom kub nce vim lawv rhiab heev rau tshav kub, ntev cua sov lub sij hawm nyob rau hauv high kub, los yog me me cross-sectional cheeb tsam ntawm lub chaw noj mov, thiab siab shear. kev ua. Cov yas uas muaj cov yam ntxwv no yog hu ua thermosensitive plastics. Xws li tawv PVC, polyvinylidene chloride, vinyl acetate copolymer, POM, polytetrafluorochloroethylene, thiab lwm yam. Thermosensitive plastics tsim los ntawm cov khoom xws li monomers, gases, thiab cov khib nyiab thaum decomposition, tshwj xeeb tshaj yog qee cov roj decomposition uas muaj irritating, corrosive, los yog tshuaj lom los ntawm cov khoom. tib neeg lub cev, khoom siv, thiab pwm. Yog li ntawd, yuav tsum tau them nyiaj mloog mus rau kev tsim pwm, xaiv cov tshuab txhaj tshuaj molding, thiab molding. Cov ntsia hlau hom txhaj tshuaj molding tshuab yuav tsum tau siv, thiab cov txheej txheem kev sib tsoo yuav tsum loj. Cov pwm thiab cov khoom siv yuav tsum yog chrome plated, thiab yuav tsum tsis muaj kaum lag luam. Lub molding kub yuav tsum nruj me ntsis tswj, thiab stabilizers yuav tsum tau ntxiv rau cov yas kom tsis muaj zog nws thermal rhiab heev.
4.2 Qee cov yas (xws li PC), txawm tias lawv muaj cov dej me me, yuav decompose nyob rau hauv qhov kub thiab txias. Cov cuab yeej no hu ua hydrophilicity, thiab nws yuav tsum tau preheated thiab qhuav.
5, Kev ntxhov siab tawg thiab tawg tawg
5.1 Qee cov plastics yog rhiab heev rau kev ntxhov siab thiab ua rau muaj kev ntxhov siab sab hauv thiab tawg thaum molding. Cov khoom yas tuaj yeem tawg nyob rau sab nraud lossis cov kuab tshuaj. Yog li ntawd, ntxiv rau ntxiv additives los txhim kho lub cracking tsis kam ntawm raw cov ntaub ntawv, yuav tsum tau them nyiaj mloog mus rau dryness thiab tsim nyog xaiv ntawm tsim tej yam kev mob kom txo tau cov kev ntxhov siab nyob rau hauv thiab ua rau kom tawg kuj. Thiab cov qauv yas tsim nyog yuav tsum raug xaiv, thiab kev ntsuas xws li teeb tsa cov khoom sib txuas yuav tsum tsis txhob raug coj los txo qis kev ntxhov siab ntau li ntau tau. Thaum tsim pwm, lub demolding lub kaum sab xis yuav tsum tau nce, thiab tsim nyog noj cov chaw nres nkoj thiab ejection mechanisms yuav tsum tau xaiv. Thaum lub sij hawm molding, cov khoom kub, pwm kub, txhaj tshuaj, thiab lub sij hawm txias yuav tsum tau kho kom haum kom tsis txhob demolding thaum cov yas yog txias heev thiab nkig. Tom qab molding, ib feem ntawm cov yas yuav tsum tau kho tom qab kev kho mob los txhim kho nws cov kev tiv thaiv tawg, tshem tawm cov kev ntxhov siab sab hauv, thiab txwv tsis pub kev sib cuag nrog cov kuab tshuaj.
5.2 Thaum lub polymer yaj nrog ib tug tej yam melt flow rate dhau los ntawm lub nozzle qhov ntawm qhov kub thiab txias thiab nws cov ndlwg npaum li cas tshaj ib tug nqi, pom tseeb transverse tawg tshwm sim nyob rau saum npoo ntawm cov yaj, uas yog hu ua melt fracture thiab tuaj yeem ua rau lub ntsej muag puas. thiab lub cev muaj zog ntawm cov khoom yas. Yog li ntawd, thaum xaiv cov polymers nrog siab yaj ntws tus nqi, nws yog ib qho tsim nyog yuav tsum tau ua kom cov ntu ntu ntawm nozzles, khiav, thiab noj cov chaw nres nkoj, txo cov kev txhaj tshuaj molding ceev, thiab nce cov khoom kub.
6, Kev ua haujlwm kub thiab txias txias
6.1 Ntau yam yas muaj cov khoom siv thermal sib txawv xws li cov cua sov tshwj xeeb, thermal conductivity, thiab thermal deformation kub. Thaum plasticizing nrog cov cua kub tshwj xeeb, yuav tsum muaj cua sov siab, thiab lub tshuab txhaj tshuaj molding nrog lub peev xwm plasticizing siab yuav tsum tau xaiv. Lub sij hawm txias ntawm cov yas uas muaj qhov kub siab thermal deformation tuaj yeem luv luv thiab demoulded thaum ntxov, tab sis txias deformation yuav tsum tau tiv thaiv tom qab demolding. Cov yas uas muaj cov thermal conductivity tsawg muaj qhov txias txias (xws li ionic polymers, uas qeeb heev), yog li qhov txias txaus yog tsim nyog los txhim kho cov nyhuv txias ntawm pwm. Kub khiav pwm yog tsim rau cov yas uas tsis tshua muaj cua sov thiab siab thermal conductivity. Cov yas uas muaj cov cua kub tshwj xeeb, tsis tshua muaj thermal conductivity, thermal deformation tsis tshua muaj kub, thiab txias txias ceev tsis yog qhov zoo rau kev kub ceev molding. Nws yog ib qho tsim nyog los xaiv cov tshuab txhaj tshuaj molding tsim nyog thiab ntxiv dag zog rau pwm txias.
6.2 Ntau yam yas yuav tsum tswj kom muaj qhov txias txias raws li lawv hom yam ntxwv thiab cov duab. Yog li cov pwm yuav tsum tau nruab nrog cua sov thiab cua txias tshuab 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 demolding, shorten lub voj voog tsim, thiab txo crystallinity. Thaum cov cua sov seem ntawm cov yas tsis txaus los tswj qhov kub thiab txias hauv pwm, lub tshuab cua sov yuav tsum tau teeb tsa kom cov pwm ntawm qhov kub thiab txias, txhawm rau tswj cov cua txias, xyuas kom muaj fluidity, txhim kho cov txheej txheem filling, lossis tswj cov pwm. qeeb txias ntawm cov khoom yas, tiv thaiv qhov tsis sib xws ntawm sab hauv thiab sab nraud ntawm cov phab ntsa tuab tuab, thiab ua kom muaj crystallinity. Rau cov ntaub ntawv uas muaj fluidity zoo, loj forming cheeb tsam, thiab cov khoom tsis sib xws, nws yog ib qho tsim nyog yuav tau siv cov cua sov los yog cua txias hloov los yog hauv zos raws li qhov teeb meem molding ntawm cov yas. Rau lub hom phiaj no, cov pwm yuav tsum tau nruab nrog cov cua txias los yog cua sov tshuab.
7, Hygroscopicity
Vim muaj ntau yam additives nyob rau hauv plastics, lawv muaj ntau theem ntawm affinity rau dej, yog li cov yas yuav roughly muab faib ua ob hom: hygroscopic, adherent thiab tsis absorbent. Cov ntsiab lus dej hauv cov ntaub ntawv yuav tsum tau tswj nyob rau hauv qhov kev tso cai, txwv tsis pub cov dej yuav dhau los ua roj lossis hydrolysis yuav tshwm sim nyob rau hauv qhov kub thiab txias, ua rau cov resin foaming, txo liquidity, thiab tsis zoo tsos thiab txhua yam khoom. Yog li, 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 los tiv thaiv kev nqus dej ntxiv thaum siv.