(23) Contraction depression Txhaj Tshuaj Molding Txheej Txheem Tsis Zoo Los Ntawm Txhais Tes

1. Tshuab:
(1) Lub qhov nozzle loj dhau, ua rau cov yaj ntws rov qab thiab cog lus. Thaum nws me dhau lawm, qhov tsis kam yog loj, thiab cov khoom ntim tsis txaus, ua rau shrinkage.
(2) Vim tsis muaj pwm locking quab yuam, lub flash kuj yuav shrinkage, thiab cov pwm locking system yuav tsum tau kuaj xyuas cov teeb meem.
(3) Yog tias cov yas yas tsis txaus, lub tshuab uas muaj cov yas loj loj yuav tsum tau xaiv los xyuas seb cov ntsia hlau thiab lub thoob puas hnav.
2. Pwm:
(1) Tus tsim ntawm lub workpiece yuav tsum xyuas kom meej cov phab ntsa tuab thiab zoo ib yam shrinkage.
(2) Lub tshuab cua txias thiab cua sov ntawm cov pwm yuav tsum xyuas kom meej tias qhov kub thiab txias ntawm txhua qhov chaw zoo ib yam. (3) Lub tshuab nqus dej yuav tsum du, thiab qhov kev tiv thaiv yuav tsum tsis txhob loj dhau. Piv txwv li, qhov loj ntawm txoj kev ntws loj, txoj kev shunt, thiab lub rooj vag yuav tsum tsim nyog, qhov smoothness yuav tsum txaus, thiab qhov chaw hloov pauv yuav tsum muaj kev hloov pauv.
(4) Rau nyias qhov chaw, qhov kub thiab txias yuav tsum tau nce ntxiv kom ntseeg tau tias cov ntaub ntawv du, thiab rau cov phab ntsa tuab, cov pwm kub yuav tsum tau txo.
(5) Lub rooj vag yuav tsum tau qhib, kom deb li deb tau ntawm cov phab ntsa tuab ntawm cov khoom ua haujlwm, thiab qhov ntim ntawm qhov dej txias yuav tsum tau nce ntxiv.
3. Yas:
Crystalline plastics yog qhov yooj yim rau shrinkage dua li cov yas tsis crystalline. Thaum ua tiav, nws yog ib qho tsim nyog yuav tsum tau ua kom cov khoom tsim nyog los yog ntxiv ib tus neeg sawv cev hloov mus rau cov yas kom nrawm crystallization thiab txo qis kev nyuaj siab.
4. Kev ua haujlwm:
(1) Yog hais tias qhov kub ntawm cov khoom thoob yog siab dhau lawm thiab lub ntim hloov tau zoo heev, tshwj xeeb tshaj yog qhov kub ntawm lub qhov cub rau pem hauv ntej, qhov kub ntawm cov yas uas tsis zoo fluidity yuav tsum tau tsim kom zoo ntxiv kom smoothness.
(2) Lub zog txhaj tshuaj, nrawm, thiab rov qab cov khoom siv tsawg dhau, lossis nrawm, thiab rov qab lub sijhawm, ua rau muaj kev kub ntxhov thiab shrinkage.
(3) Kev txhaj tshuaj siab yog noj thaum noj ntau npaum li cas, piv txwv li, lub ncoo tsis loj, thiab thaum nws tsawg dhau, cov khoom siv tsis txaus.
(4) Rau qhov chaw uas tsis xav tau qhov tseeb, tom qab txhaj tshuaj thiab kev tswj xyuas lub siab, cov txheej txheej sab nrauv yog qhov yooj yim condensed thiab hardened, thaum lub qhaub cij tseem yog mos thiab tuaj yeem raug tshem tawm. Thaum ntxov ejection ntawm pwm thiab qeeb cua txias hauv huab cua los yog dej kub tuaj yeem ua rau lub shrinkage thiab indentation du yam tsis muaj kev cuam tshuam rau kev siv.
(5) "Dents" yog tshwm sim los ntawm lub hauv paus hauv zos shrinkage tshwm sim los ntawm lub qhov rooj kaw los yog tsis muaj cov khoom txhaj tshuaj. Kev nyuaj siab lossis microindentation ntawm qhov chaw txhaj tshuaj molded cov khoom yog ib qho teeb meem qub hauv cov txheej txheem txhaj tshuaj molding. Cov dents feem ntau tshwm sim los ntawm kev nce hauv zos hauv qhov shrinkage tus nqi ntawm cov khoom yas los ntawm kev nce ntawm phab ntsa thickness. Tej zaum lawv yuav tshwm sim ze rau sab nraud ntawm cov ces kaum ntse ntse los yog ntawm cov kev hloov pauv sai ntawm phab ntsa tuab, xws li pob, stiffeners, lossis tom qab kev txhawb nqa, thiab qee zaum kuj nyob rau qee qhov chaw txawv. Lub hauv paus ua rau cov dents yog thermal expansion thiab contraction ntawm cov khoom, raws li cov coefficient ntawm thermal expansion ntawm thermoplastics yog heev. Lub degree ntawm kev nthuav dav thiab kev cog lus nyob ntawm ntau yam, ntawm cov kev ua haujlwm ntawm cov yas, qhov siab tshaj plaws thiab qhov kub thiab txias, thiab cov pwm kab noj hniav yog qhov tseem ceeb tshaj plaws. Qhov luaj li cas thiab cov duab ntawm kev txhaj tshuaj molded qhov chaw, nrog rau qhov txias ceev thiab qhov sib xws kuj yog qhov cuam tshuam rau lawv. Tus nqi ntawm expansion thiab shrinkage ntawm cov ntaub ntawv yas thaum lub sij hawm molding txheej txheem muaj feem xyuam rau thermal expansion coefficient ntawm cov txheej txheem yas, uas yog hu ua "molding shrinkage". Raws li cov pwm txias thiab cog lus, cov pwm poob kev sib cuag nrog qhov txias ntawm qhov pwm kab noj hniav. Nyob rau lub sijhawm no, qhov ua kom txias txias txo qis. Tom qab cov pwm txuas ntxiv txias, cov pwm txuas ntxiv mus rau kev cog lus, thiab cov nyiaj shrinkage nyob ntawm qhov sib xyaw ua ke ntawm ntau yam. Lub kaum ntse ntse ntawm qhov molded qhov txias ceev tshaj plaws thiab tawv ua ntej tshaj lwm yam khoom. Qhov tuab nyob ze ntawm qhov nruab nrab ntawm qhov molded yog qhov deb tshaj plaws ntawm qhov chaw txias ntawm cov pwm kab noj hniav, dhau los ua qhov kawg ntawm qhov molded ib feem kom tso cua sov. Tom qab cov khoom ntawm cov ces kaum yog solidified, raws li cov yaj nyob ze ntawm qhov chaw ntawm qhov chaw txias, qhov molded ib feem yuav txuas ntxiv mus. Lub dav hlau nruab nrab ntawm cov kaum ntse ntse tsuas tuaj yeem ua kom txias unilaterally, thiab nws lub zog tsis siab npaum li cov khoom ntawm cov ces kaum ntse. Cov cua txias shrinkage ntawm cov khoom yas ntawm qhov nruab nrab ntawm lub workpiece rub tawm sab hauv qhov chaw tsis muaj zog ntawm cov ces kaum txias txias thiab qhov txias dua. Yog li ntawd, dents yog tsim nyob rau saum npoo ntawm qhov txhaj tshuaj molded ib feem. Lub xub ntiag ntawm dents qhia tau hais tias lub molding shrinkage ntawm no yog siab tshaj qhov shrinkage ntawm nws cov cheeb tsam ib puag ncig. Yog hais tias lub shrinkage ntawm molded ib feem ntawm ib qhov chaw siab tshaj qhov ntawm lwm yam, ces yog vim li cas rau lub warpage ntawm molded ib feem. Kev ntxhov siab nyob hauv cov pwm tuaj yeem txo qhov cuam tshuam lub zog thiab kub tsis kam ntawm qhov molded. Qee qhov xwm txheej, kev kho cov txheej txheem tuaj yeem zam kev tsim cov dents. Piv txwv li, thaum lub sij hawm tuav cov txheej txheem ntawm molded ib feem, ntxiv cov khoom yas yog txhaj rau hauv pwm kab noj hniav kom them rau pwm shrinkage. Feem ntau, lub rooj vag yog thinner dua li ntawm qhov seem. Thaum cov pwm tseem kub heev thiab txuas ntxiv rau kev cog lus, lub rooj vag me me tau ruaj khov, thiab tom qab solidification, kev tuav ruaj ruaj tsis cuam tshuam rau cov pwm hauv pwm kab noj hniav. Lub siab shrinkage ntawm molded qhov chaw ua los ntawm semi crystalline yas cov ntaub ntawv ua rau cov dents teeb meem loj dua; Lub molding shrinkage ntawm cov ntaub ntawv uas tsis yog crystalline yog tsawg, uas minimizes dents; Cov ntaub ntawv uas sau thiab tswj kev txhawb nqa muaj qhov qis qis dua thiab tsis tshua muaj peev xwm tsim cov dents. Thick txhaj molded qhov chaw muaj lub sijhawm txias txias thiab tuaj yeem ua rau muaj kev cuam tshuam loj. Yog li ntawd, loj thickness yog lub hauv paus ua rau dents. Kev saib xyuas yuav tsum tau them nyiaj thaum tsim kom tsis txhob muaj cov phab ntsa tuab kom ntau li ntau tau. Yog tias cov phab ntsa tuab tsis tuaj yeem zam tau, nws yuav tsum tau tsim los ua qhov hollow, thiab cov khoom tuab yuav tsum hloov mus rau qhov nominal phab ntsa tuab. Hloov cov ces kaum ntse nrog cov arcs loj tuaj yeem tshem tawm lossis txo cov dents tsim nyob ze ntawm cov ces kaum ntse