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Yas Txhaj Tshuaj Moulding ntsws

Kev txhaj tshuaj yas molding shrinkage yog ib qho ntawm cov khoom thaum cov khoom kub txias. Tus nqi ntawm txhaj moulding shrankage yog qhov xav tau nyob rau hauv kev txiav txim siab zaum kawg workpiece qhov ntev. Tus nqi qhia tus nqi ntawm kev cog lus uas ib pawg neeg ua haujlwm nthuav tawm tom qab nws tau tshem tawm ntawm pwm thiab tom qab ntawd txias ntawm 23C rau lub sijhawm 48 teev.

Kev Ntsws yog txiav txim siab los ntawm cov kab zauv hauv qab no:

S = (Lm-Lf) / Lf * 100%

qhov twg S yog cov pwm shrinkage tus nqi, Lr qhov kawg workpiece qhov ntev (hauv. lossis mm), thiab Lm cov pwm kab noj qhov ntev (hauv lossis hli). Hom thiab kev faib tawm ntawm cov khoom yas muaj cov nqi sib txawv ntawm shrinkage. Lub shrinkage tuaj yeem cuam tshuam los ntawm tus lej hloov xws li txias lub zog workpiece thickness, txhaj tshuaj thiab nyob hauv cov pressures. Qhov sib ntxiv ntawm cov ntxig thiab cov txhawb nqa, xws li iav fiber ntau los yog cov ntxhia pob zeb, tuaj yeem txo qhov shrinkage.

Ntsws cov khoom lag luam yas tom qab ua cov khoom yog ntau yam, tab sis crystalline thiab amorphous polymers ntsws sib txawv. Txhua tus ua hauj lwm plua plav ntsws tom qab ua tau yooj yim raws li qhov ua tiav ntawm lawv qhov kev hloov pauv thiab cov thermal ntim tau thaum lawv txias los ntawm qhov ntsuas kub.

Amorphous cov ntaub ntawv muaj qis qis qis dua. Thaum cov ntaub ntawv amorphous txias thaum lub sijhawm txias ntawm cov txheej txheem txhaj tshuaj molding, lawv rov qab mus rau qhov txhav plymer. Lub kaw lus polymer uas tsim cov khoom siv amorphous tsis muaj qhov qhia tshwj xeeb. Piv txwv pf amorphous cov ntaub ntawv yog polycarbonate, ABS, thiab polystyrene.

Cov khoom siv Crystalling muaj cov ntsiab lus tsis sib xws crystalline point Cov polymer chains coj lawv tus kheej hauv cov txheej txheem molecular. Cov chaw txiav txim no yog cov muaju uas tsim thaum lub polymer txias los ntawm nws lub xeev yaj. Txog semicrystalline polymer cov ntaub ntawv, kev tsim thiab nce ntim ntawm cov saw hlau nyob hauv cov chaw no. cov injectio molding shrinkage rau cov khoom siv semicrystalline yog siab dua rau ntawm cov khoom siv amorphous. Piv txwv ntawm cov ntaub ntawv crystalline yog nylon, polypropylene, thiab polyethylene.Qhov teev cov xov tooj ntawm cov khoom siv yas, ob qho tib si amorphous thiab semicrystalline, thiab lawv cov pwm txhaws.

Ntsws rau cov thermoplastics /%
khoom siv puab ntsws khoom siv  puab ntsws khoom siv puab ntsws
ABS 0.4-0.7 polycarbonate 0,5-0,7 PPO 0,5-0,7
Acrylic 0.2-1.0 PC-ABS 0,5-0,7 polystyrene 0.4-0.8
ABS-nylon 1.0-1.2 PC-PBT 0.8-1.0 Polysulfone 0.1-0.3
Acetal 2.0-3.5 PC-TSIAJ 0.8-1.0 PBT 1.7-2.3
Nylon 6 0.7-1.5 Polyethylene 1.0-3.0 TSIAJ 1.7-2.3
Nylon 6,6 1.0-2.5 Polypropylene 0.8-3.0 TPO 1.2-1.6
PEI 0,5-0,7        

Cov txiaj ntsig ntsws tsis sib xws ua cov txhais tau tias kev ua kom zoo rau kev ua kom tau cov amorphous polymers zoo dua li cov uas rau cov crystalline polymers, vim hais tias crystallites muaj ntau xaj thiab zoo dua ntim ntawm cov saw polymer, cov kev hloov theem nce shrinkage ntau. Tab sis nrog amorphous plastics, qhov no tsuas yog tib qho xwb thiab yog yooj yim xam.

Rau amorphous polymers, shrinkage qhov tseem ceeb tsis yog tsuas yog qis, tab sis shrinkage nws tus kheej yog qhov tshwm sim nrawm. Rau qhov raug amorphous polymer xws li PMMA, lub ntsws yuav ua raws li 1-5 hli / m. Qhov no yog vim muaj cua txias los ntawm hais txog 150 (qhov kub ntawm cov yaj) mus rau 23C (chav sov) thiab tuaj yeem cuam tshuam nrog cov coefficient ntawm thermal expansiono.


Lub sij hawm tshaj tawm: Sep-19-2020