Qhov yuam kev loj ntawm cov khoom yas feem ntau yog los ntawm qhov shrinkage ntawm plastics thaum lub sij hawm molding txheej txheem thiab instability ntawm ntau yam influencing yam. Tsuas yog muab tso rau, nws yog txhaj tshuaj rhuab thiab melted yas rau hauv pwm, thiab tom qab txias thiab shaping, nws ntim yuav me dua cov pwm kab noj hniav. Tus nqi txo thiab qhov hloov pauv ntawm cov txheej txheem ua ke txiav txim siab qhov tseeb ntawm qhov kawg loj.
Tshwj xeeb, qhov yuam kev feem ntau yog los ntawm cov hauv qab no:
Lub hauv paus ua rau ntawm cov yas me me yuam kev yog thawj zaug thiab qhov tseem ceeb ntawm lub cev ntawm nws cov ntaub ntawv polymer. Los ntawm qhov siab - kub filling ntawm pwm mus rau chav tsev kub solidification, lub ntim ntawm yas yaj yuav inevitably shrinkage, uas yog hu ua molding shrinkage. Nws tsis yog tus nqi ruaj khov, tab sis qhov hloov pauv tau cuam tshuam los ntawm ntau yam.
Crystallization tus cwj pwm thiab kev taw qhia cov nyhuv ntawm cov resin: Rau cov khoom siv crystalline xws li PA66 thiab POM, cov saw hlau molecular yuav raug teeb tsa ua ntu zus los ua ib lub lattice thaum txias, thiab cov ntim tshwj xeeb yuav hloov pauv ntau. Tus nqi shrinkage feem ntau yog nruab nrab ntawm 1.5% thiab 3.0%, thiab qhov hloov pauv amplitude yog loj; Cov yas tsis muaj crystalline (xws li ABS thiab PC) muaj qhov tsis zoo ntawm cov saw hlau molecular khov, qis qis qis (kwv yees li 0.4% ~ 0.8%), thiab kev ruaj ntseg yooj yim dua. Tsis tas li ntawd, thaum lub sij hawm txhaws ntawm cov pwm yaj, cov saw hlau molecular yog ncab raws cov kev taw qhia ntws, thiab qhov kev taw qhia khov no yuav ua rau muaj kev ntxhov siab tom qab demolding, uas ua rau tsis sib haum xeeb ntawm cov kev taw qhia ntws thiab cov kev taw qhia ntsug ntawm cov khoom, uas yog, anisotropy. Qhov no yog qhov sib sib zog nqus sab hauv ua rau cov khoom warping deformation.
Kev cuam tshuam ntawm cov khoom siv raw khoom thiab cov khoom siv rov ua dua: Cov dej noo ntawm cov ntaub ntawv raw tuaj yeem hloov cov viscosity yaj, tshwj xeeb tshaj yog rau cov khoom nqus dej noo xws li PA, qhov twg cov dej noo ua raws li cov yas yas thiab ua rau cov molding shrinkage. Nyob rau tib lub sijhawm, ntxiv cov khoom siv rov ua dua tshiab yuav hloov lub yaj qhov ntsuas vim yog cov saw hlau molecular tawg. Yog tias sib xyaw tsis sib xws, qhov ntev ntev ntawm cov khoom sib txawv ntawm cov khoom yuav raug cuam tshuam loj heev.
2, Pwm manufacturing thiab qauv: "lub cev qab nthab" ntawm precision
Cov kab noj hniav pwm yog "tus tswv" ntawm cov khoom, tab sis kev tsim khoom raug thiab lub xeev ntawm tus tswv nws tus kheej txiav txim siab txog qhov txwv ntawm cov khoom loj.
1
Tsis txaus ua kam rau ua thiab them nyiaj
Muaj inevitably mechanical processing tolerances nyob rau hauv pwm manufacturing, thiab tseem ceeb tshaj, yog hais tias tus shrinkage tus nqi yog tsis coj mus rau hauv tus account thaum lub sij hawm tsim (xws li tsis xav txog lub orientation ntawm iav fibers los yog post extrusion shrinkage), txawm hais tias cov pwm ua tiav mus rau qib micrometer, cov khoom zaum kawg tseem yuav pov tseg nrog loj sib txawv.
2
Rigid deformation thiab hnav
Kev txhaj tshuaj siab feem ntau nce mus txog kaum tawm megapascals. Yog hais tias lub rigidity ntawm pwm yog tsis txaus, cov pwm kab noj hniav yuav undergo elastic expansion nyob rau hauv kev kub siab, ua rau cov phab ntsa thickness ntawm cov khoom. Nyob rau tib lub sijhawm, rau cov yas nrog ntxiv fiberglass (GF), qhov chaw ntawm cov pwm kab noj hniav yuav raug eroded los ntawm cov yaj, uas ua rau abrasive hnav. Tom qab ntev - lub sij hawm ntau lawm, qhov loj ntawm pwm kab noj hniav yuav nce, thiab phab ntsa thickness ntawm cov khoom yuav kuj nce raws li. Tsis tas li ntawd, hnav thiab tsim kua muag ntawm cov txheej txheem kev taw qhia tuaj yeem ua rau cov pwm tsis zoo, ncaj qha ua rau irreversible geometric dimensional deviations.
cov txheej txheem hloov pauv hloov pauv
Cov txheej txheem tsis ua haujlwm yog qhov ua tau zoo tshaj plaws thiab nquag hloov pauv hauv cov txheej txheem txhaj tshuaj molding, uas ncaj qha txiav txim siab tus cwj pwm ntws, tus nqi txias, thiab lub xeev shrinkage ntawm cov yaj hauv pwm kab noj hniav. Ntawm lawv, kev sib koom ua ke thiab kev ua si ntawm qhov kub thiab txias, siab, thiab lub sijhawm ua rau lub zog loj ntawm qhov yuam kev.
Kev tswj qhov kub thiab txias khiav los ntawm tag nrho cov txheej txheem txhaj tshuaj molding, nrog rau qhov kub thiab txias, lub taub hau kub, thiab pwm kub. Cov pwm kub yog qhov ntsuas kub uas muaj qhov cuam tshuam loj tshaj plaws ntawm qhov tseeb ntawm qhov khoom. Cov pwm kub ncaj qha tswj cov cua txias thiab shaping txheej txheem ntawm cov khoom. Thaum lub sij hawm lub sij hawm los ntawm lub freezing ntawm lub sprue mus rau demolding ntawm cov khoom, qhov kub ntawm pwm txiav txim lub crystallinity ntawm lub crystalline yas. Raws li pwm kub nce, crystallinity nce thiab shrinkage intensifies. Tab sis yog tias pwm kub qis dhau los yog tsis sib xws, qhov txias tsis txaus ntawm cov khoom tuaj yeem ua rau qhov tsis txaus ntseeg. Rau kev txhaj tshuaj molding precision, pwm kub yuav tsum tau tswj kom meej nyob rau hauv ib qho kev tshwj xeeb (xws li 35-45℃C) thiaj li tswj tau qhov loj me me hauv cov ntsuas tsim nyog.
Qhov kub ntawm cov khoom thoob yog lwm qhov sib txawv tseem ceeb. Yog tias qhov kub thiab txias dhau (dhau qhov kev pom zoo ua haujlwm ntawm 5-10 ° C), viscosity ntawm cov yas yaj yuav txo qis thiab cov dej ntws yuav muaj zog heev. Thaum lub caij txias, qhov chaw dawb rau molecular saw txav yuav nce, qhov shrinkage yuav nce, thiab qhov sib txawv ntawm qhov loj tuaj yeem ncav cuag 0.1% -0.3%; Yog tias qhov kub thiab txias qis dhau lawm, cov dej ntws ntws tsis zoo, qhov ntim tsis txaus, thiab cov khoom loj yog qhov me me.
Ntawm cov txheej txheem ntau yam, lub zog tuav muaj qhov cuam tshuam loj tshaj plaws ntawm qhov loj ntawm cov khoom. Thaum lub sij hawm tuav lub siab, nruam ntxiv ntawm cov khoom siv rau cov pwm kab noj hniav yog siv los them rau qhov txias shrinkage - tsis txaus tuav lub siab tuaj yeem ua rau ntau qhov shrinkage thiab me me; Kev tuav ntau dhau tuaj yeem ua rau cov khoom loj loj lossis txawm tias flash npoo. Cov ntaub ntawv siv tau qhia tau hais tias rau txhua qhov kev hloov pauv ntawm 10MPa hauv kev tuav lub siab, qhov sib txawv ntawm qee qhov precision yas tuaj yeem nce ntau dua 0.02mm. Txoj kev tshawb no kuj qhia tau hais tias lub thinner phab ntsa ntawm molded ib feem, qhov ntau dua qhov cuam tshuam ntawm kev tuav tuav ntawm qhov loj. Lub sijhawm tuav tsis tuaj yeem tsis quav ntsej ib yam. Yog tias lub sijhawm luv dhau, nws tsis tuaj yeem them nyiaj rau qhov shrinkage, thiab yog tias lub sijhawm ntev dhau, nws yuav ua rau overfilling.
Kev txhaj tshuaj siab thiab kev txhaj tshuaj nrawm feem ntau cuam tshuam rau theem filling. Lub siab txhaj tshuaj tsawg dhau, ua rau nws nyuaj rau cov yaj kom puv lub pwm kab noj hniav, tshwj xeeb tshaj yog rau cov txheej txheem nyias nyias - cov phab ntsa uas ua rau luv luv; Kev txhaj tshuaj nrawm dua thiab siab dua, ua ke nrog qhov tsim nyog txuas ntxiv thiab tuav lub sijhawm, muaj txiaj ntsig zoo rau kev kov yeej qhov tsis muaj qhov tsis txaus ntseeg.
Qhov cuam tshuam ntawm kev txhaj tshuaj nrawm yog hloov maj mam. Kev txhaj tshuaj ceev ceev yuav ua rau muaj zog shear ntws ntawm cov yaj hauv cov channel thiab kab noj hniav, ua rau qhov kub thiab txias hauv zos nce thiab viscosity txo vim shear cua sov. Txawm li cas los xij, nyob rau tib lub sijhawm, shear flow field induces orientation of polymer chains along the flow direction. Qhov kev taw qhia khov kho no ua rau muaj kev ntxhov siab tom qab demolding, ua rau muaj qhov sib txawv ntawm cov khoom sib txawv ntawm cov khoom ntws thiab cov kev taw qhia perpendicular - piv txwv li anisotropic shrinkage. Qhov no yog ib qho ntawm cov hauv paus ntsiab lus ntawm cov khoom warping thiab deformation.
Tag nrho cov txheej txheem yuav tsum nruj me ntsis tswj raws li tus txheej txheem yuav tsum tau, tshwj xeeb tshaj yog cov molding voj voog ntawm txhua yam ntawm cov yas yuav tsum zoo ib yam thiab tsis tuaj yeem hloov arbitrarily. Txhua qhov kev hloov pauv me me hauv qhov kub thiab txias, siab, thiab lub sijhawm yuav raug cuam tshuam los ntawm qhov kawg ntawm qhov kev ua siab ntev los ntawm cov teebmeem loj.
lub 'hardware qab nthab' ntawm dimensional yuam kev
Qhov tseeb ntawm lub tshuab txhaj tshuaj molding nws tus kheej txiav txim siab seb cov txheej txheem cov lus qhia tuaj yeem ua ncaj ncees thiab yog lub hauv paus ntawm lub cev ntawm qhov raug. Yog tias qhov tseeb ntawm cov khoom siv nws tus kheej tsis txaus, txawm tias cov txheej txheem meej tshaj plaws tsis tuaj yeem hloov mus rau hauv cov khoom tsim nyog.
Precision txhaj tshuaj molding yuav tsum tau tswj qhov system ntawm txhaj tshuaj molding tshuab yuav tsum xyuas kom meej zoo repeatability ntawm ntau yam txheej txheem tsis. Qhov no yuav tsum tau muaj ntau yam - theem tawm tswv yim tswj cov txheej txheem tsis xws li txhaj tshuaj ntim, txhaj tshuaj, txhaj ceev, tuav lub siab, rov qab siab, thiab ntsia hlau ceev, thaum PID controllers yog siv los tswj qhov kub thiab txias ntawm lub thoob thiab lub nozzle.
Niaj hnub nimno siab -kawg servo txhaj tshuaj molding tshuab tuaj yeem ua tiav qhov hnyav dua qhov tseeb ntawm tsawg dua 3 ‰ thiab pwm qhib qhov tseeb ntawm ± 0.2 hli los ntawm kaw - voj tswj. Qhov kaw - voj tswj ntawm qhov kev txhaj tshuaj tuaj yeem ua tiav qhov rov ua qhov tseeb ntawm qhov tsis pub dhau 0.01mm. Raws li kev sib piv, kev txhaj tshuaj hloov pauv lub sijhawm ntawm lub tshuab txhaj tshuaj molding ib txwm yog li 300ms, thaum lub kaw tag nrho -loop ultra precision txhaj tshuaj molding tshuab zoo dua li qib no.
Lub tshuab hydraulic yog lub zog lub plawv ntawm lub tshuab txhaj tshuaj molding. Precision txhaj tshuaj molding tshuab feem ntau yuav tsum tau kaw- voj tswj cov cua kub thiab txias ntawm cov roj hydraulic kom ruaj khov ntawm cov roj kub ntawm ib ncig ntawm 50-55 ° C, txhawm rau tiv thaiv cov viscosity thiab ntws tus nqi hloov pauv los ntawm kev hloov pauv ntawm cov roj kub, uas tuaj yeem ua rau tsis muaj kev ruaj ntseg ntawm cov txheej txheem. Qhov siab tshaj servo hydraulic system tuaj yeem ua tiav qhov kev hloov pauv siab hauv qab ± 0.5bar, thiab qhov ua tau zoo dua ntawm lub ntsiab lus txav mus txog ± 0.05%. Qhov tseeb ntawm qhov hloov pauv sensor yuav tsum muaj tsawg kawg yog 0.1 hli txhawm rau tswj kev ntsuas stroke, txhaj tshuaj, thiab cov khoom seem ntawm cov ntaub qhwv tuab, kom ntseeg tau tias qhov ntim txhaj tshuaj txhua zaus.
Kev txhaj tshuaj siab yuav tsum tau ua rau kev txhaj tshuaj molding yog ntau dua li qhov kev txhaj tshuaj molding zoo tib yam - kev txhaj tshuaj molding zoo ib yam yuav tsum tau 40-120MPa, thaum precision txhaj molding yuav tsum tau nce mus rau 180-250MPa, thiab qee qhov txawm tias mus txog 415MPa. Nyob rau hauv xws li molding siab, yog hais tias lub rigidity ntawm txhaj molding tshuab lub clamping system yog tsis txaus, lub template yuav undergo elastic deformation, ua rau cov pwm parting nto qhib thiab cov khoom tsim burrs, uas ua rau ib tug txo nyob rau hauv qhov tseeb. Yog li ntawd, high rigidity template tsim thiab uniform locking quab yuam faib yog prerequisites kom paub tseeb tias qhov tseeb.
Kev hnav ntawm cov ntsia hlau thiab cov thoob yog ib qho ua rau cov khoom raug degradation. Tshwj xeeb tshaj yog lub nplhaib thim rov qab (tseem hu ua lub nplhaib roj hmab), nws hnav hnyav heev tom qab ntev - lub sij hawm tsim cov khoom siv ntxiv (xws li fiberglass). Kev sib khi tsis zoo ntawm lub nplhaib thim rov qab tuaj yeem ua rau cov yaj mus rau reflux thaum txhaj tshuaj, ua rau kev ntsuas tsis ruaj khov thiab hloov pauv ntawm qhov kawg ntawm kev txhaj tshuaj. Qhov no yog qhia ncaj qha nyob rau hauv lub dispersion ntawm qhov hnyav ntawm txhua yam khoom molded thiab qhov sib txawv ntawm qhov loj ntawm batches
5, Kev cuam tshuam ib puag ncig: zais thiab tsis tu ncua 'sab nraud hloov pauv'
Cov xwm txheej ib puag ncig yog qhov yooj yim tshaj plaws saib tab sis tsis tu ncua muaj kev cuam tshuam kev hloov pauv hauv cov txheej txheem txhaj tshuaj molding.
1. Lub caij nyoog hloov pauv ntawm ib puag ncig kub
Qhov kub hloov pauv hauv qhov chaw ua haujlwm ib puag ncig ncaj qha cuam tshuam rau kev ua kom txias ntawm cov pwm thiab kev tswj ntawm qhov kub thiab txias. Qhov kub thiab txias sib txawv ntawm nruab hnub thiab hmo ntuj tuaj yeem ua rau cov pwm tuaj yeem nthuav dav thiab cog lus, thiab kev tswj qhov kub thiab txias ntawm cov pwm kub tswj tau cuam tshuam los ntawm ib puag ncig cuam tshuam, ua rau tsis ruaj khov thiab qhov hloov pauv ntawm qhov loj ntawm cov khoom hauv tib batch. Cov ntaub ntawv ntsuas qhov tseeb qhia tau hais tias txhua txhua 5℃C nce hauv qhov kub thiab txias, qhov sib txawv ntawm cov khoom siv PP nce 12% -15%. Siv cov ntaub ntawv PC ua piv txwv, rau txhua txhua 5 ° C hloov pauv hauv qhov kub thiab txias, qhov sib txawv ntawm qhov sib txawv tuaj yeem ncav cuag 0.05% -0.1%. Txhaj tshuaj molded qhov chaw uas tsim nyob rau hauv ib puag ncig uas tsis muaj qhov kub thiab txias feem ntau pom tshwm sim xws li txo qhov loj me thiab nce warpage. Qhov no xav kom cov neeg tsim khoom kho cov txheej txheem kub ntawm cov khoom siv thiab pwm hauv lub sijhawm raws li kev hloov pauv hauv ib puag ncig sab nraud.
2. Cov av noo thiab noo noo nqus nthuav dav ntawm cov ntaub ntawv
The influence of humidity on plastic size is also significant. Polyamide materials, represented by nylon (PA), contain polar amide groups in their molecular chains and are easily bound to water molecules. The equilibrium moisture content of non reinforced PA6 or PA66 can reach 3% under standard atmospheric conditions (23 ° C, 50% RH). In high humidity environments (relative humidity>60%), qhov loj me tuaj yeem ncav cuag 0.2% -0.5%. Thaum cov av noo hloov los ntawm 10%, qhov hloov pauv loj ntawm cov ntaub ntawv nylon tuaj yeem ncav cuag 0.1% -0.3%.
Dab tsi yog qhov nyuaj dua yog tias qhov nqus dej noo thiab nthuav tawm ntawm qee cov ntaub ntawv nthuav tawm cov yam ntxwv anisotropic - qhov siab dua ntawm cov av noo ib puag ncig thiab lub sijhawm ntev dua, qhov loj ntawm cov iav fiber ntau ntxiv PA66 cov khoom yuav dhau los, thiab qhov hloov pauv loj nyob rau hauv txoj kev khiav ntsug yog ntau dua li qhov kev coj ua. Qhov no txhais tau hais tias txawm tias nrog tib cov khoom thiab cov khoom lag luam, cov lus teb ntawm qhov sib txawv ntawm cov av noo sib txawv hauv cov lus qhia sib txawv, ua rau muaj kev sib tw ntxiv rau kev tsim cov khoom siv precision fittings.
3. Thermal deformation ntawm cov khoom siv
Lub thermal deformation tshwm sim los ntawm kev ua haujlwm ntev - lub sijhawm ua haujlwm ntawm cov khoom siv kuj tuaj yeem ua rau qhov sib txawv ntawm qhov sib txawv. Ntau yam khoom ntawm lub tshuab txhaj tshuaj molding nthuav dav vim muaj kev sib txhuam thaum lub sijhawm ua haujlwm tas mus li, uas tuaj yeem hloov pauv qhov tseem ceeb xws li pwm clamping raug thiab txhaj tshuaj stroke. Qhov kev qeeb qeeb thiab txuas mus ntxiv no feem ntau nyuaj rau cov neeg ua haujlwm txhawm rau txheeb xyuas tam sim.
6, Logic ntawm System Control
Hauv cov ntsiab lus, cov txheej txheem kev txhaj tshuaj molding tsis, cov cuab yeej raug, thiab kev cuam tshuam ib puag ncig tsis yog kev cuam tshuam, tab sis yog ib qho kev sib txuas ua ke thiab kis tau los ntawm txheej. Cov txheej txheem tsis yog "tiag tiag- lub sijhawm tswj hwm", cov khoom siv raug yog "ua tiav lav", thiab ib puag ncig yog "cov suab nrov tom qab". Txhawm rau kom ntseeg tau qhov tseeb qhov tseeb, yuav tsum tsim kom muaj kev tswj hwm lub siab: xaiv siab -precision kaw- voj voog txhaj tshuaj molding tshuab thiab ua haujlwm tsis tu ncua; Txais pwm kub tshuab thiab rhiav kub tswj qhov system kom cais ib puag ncig cuam tshuam; Ua kom nruj kom qhuav thiab tswj cov av noo rau cov ntaub ntawv rhiab heev (xws li PA); Thiab tsis tu ncua saib xyuas kev ruaj ntseg ntawm cov txheej txheem tsis dhau los ntawm Statistical Process Control (SPC). Tsuas yog los ntawm kev tswj peb qhov loj me raws li cov organic tag nrho tuaj yeem ua qhov yuam kev tsis tu ncua thiab ruaj khov nyob rau hauv cheeb tsam tsim kev zam.
