PVC yog muab faib ua PVC (UPVC) thiab hloov tau yooj yim PVC. Nws cov yam ntxwv muaj xws li thermal rhiab heev, susceptibility rau decomposition, tsis zoo txaus zog, thiab muaj zog corrosiveness; Tsis tas li ntawd, plasticizers uas muaj nyob rau hauv nws zoo li leaching tawm, thiab nws tsis tuaj yeem raug rau lub sijhawm ntev ntawm qhov kub thiab txias. Yog li ntawd, nws cov molding nthuav tawm qhov kev sib tw loj dua piv rau cov yas zoo tib yam.
I. Yellowing, Scorching, Black Spots, thiab Dub Streaks (Feem ntau)
Phenomena: Yellowing ntawm cov khoom tiav, xim av streaks, dub me ntsis, scorching, thiab pungent tsw.
Ua rau:
- Cov khoom kub yog siab dhau heev lawm, ua rau kom ceev thermal decomposition ntawm PVC.
- Screw rotation ceev ceev heev, ua rau shear cua sov ntau dhau.
- Lub sijhawm nyob hauv lub thoob yog ntev heev.
- Cov khoom sib sau ua ke thiab carbonizes hauv "qhov chaw tuag" hauv cov ntsia hlau lossis lub thoob.
- Cov ntsiab lus stabilizer tsis txaus lossis tsis sib xws.
Kev daws:
- nruj me ntsis tswj cov khoom kub: tswj nws ntawm 160-190 degree; nruj me ntsis txwv tsis pub tshaj 200 degree.
- Txo cov ntsia hlau tig ceev kom txo qis shear cua sov.
- Shorten lub voj voog molding; lub thoob yuav tsum tau purged tag ua ntej kaw lub tshuab.
- Tsis tu ncua ntxuav cov ntsia hlau thiab lub thoob.
- Xyuas kom meej tias lub stabilizer yog uniformly dispersed nyob rau hauv qhov sib tov, thiab tsis txhob siv cov khoom siv tas sij hawm.
II. Silver Streaks, Gas Marks, thiab Flow Marks
Phenomena: Silver streaks, pos huab, lossis linear streaks ntawm qhov chaw.
Ua rau:
- Cov khoom nyoos muaj cov dej noo, uas vaporizes ntawm qhov kub thiab txias.
- Me ntsis thermal decomposition tsim hydrogen chloride roj.
- Kev txhaj tshuaj ceev yog siab dhau, ua rau huab cua nkag.
- Kev ua pa tsis zoo hauv pwm.
- Tsis txaus rov qab siab ua rau tsis sib xws plasticization.
Kev daws:
- Qhuav cov khoom raw ntawm 60-70℃rau 1-2 teev.
- Txo cov khoom kub kom tsis txhob decomposition.
- Txo qhov kev txhaj tshuaj ceev thaum lub sij hawm thawj zaug kom paub meej tias cov pwm puv.
- Txhim kho pwm qhov cua.
- Tsim nyog nce lub siab rov qab.
III. Kev txhaj tshuaj luv luv, tsis sib xws, thiab tsis txaus sau
Cov tsos mob: Cov ces kaum ntse ntse, nyias-cov phab ntsa, thiab sab sab.
Ua rau:
- Cov khoom kub thiab / lossis pwm kub qis dhau, ua rau tsis muaj dej txaus.
- Kev txhaj tshuaj tsis txaus thiab / lossis kev txhaj tshuaj nrawm.
- Cov khiav thiab/los yog rooj vag me dhau.
- Pwm qhov cua tsis zoo.
- Kev faib tawm tsis sib xws ntawm cov yas yas hauv PVC hloov tau yooj yim, ua rau muaj teeb meem hauv zos viscous ntws.
Kev daws:
- Tsim nyog nce cov khoom kub thiab pwm kub.
- Nce txhaj tshuaj; sau cov pwm ntawm qhov nruab nrab - mus rau - kev txhaj tshuaj tsawg.
- Txhim kho cov rooj vag thiab cov neeg khiav dej num.
- Txhim kho pwm qhov cua.
- Xyuas kom meej sib xyaw ntawm cov khoom kom lav tau zoo plasticization.
IV. Cov kab zoo nkauj Weld thiab tsis muaj zog
Cov tsos mob: Sib sib zog nqus thiab tsis muaj xim (dawb) weld kab; nquag mus tawg.
Ua rau:
- Tsawg yaj kub thiab / lossis pwm kub, ua rau tsis zoo fusion.
- Kev txhaj tshuaj qeeb qeeb, ua rau cov yaj ntws mus rau pem hauv ntej kom txias ua ntej.
- Kev ua pa tsis zoo, ua rau huab cua nkag rau ntawm txoj kab weld.
- Qhov chaw qhov rooj tsis raug.
Kev daws:
- Ua kom kub kub thiab pwm kub.
- Tsim nyog nce kev txhaj tshuaj nrawm.
- Ntxiv vent grooves ntawm qhov chaw weld.
- Optimize lub rooj vag tso rau kom luv txoj kev ntws ntws.
V. Ntxoov ntxoo thiab dab dej cim
Phenomenon: Kev nyuaj siab tshwm sim ntawm qhov chaw tav, tus thawj coj, thiab tuab - ntu phab ntsa.
Ua rau:
- Kev tuav tsis txaus; tuav lub sij hawm luv heev.
- Txhaj tshuaj tsawg dhau lawm.
- Lub rooj vag me me dhau, ua rau lub sijhawm khov ua ntej.
- Melt kub yog siab dhau heev lawm, uas ua rau ntau shrinkage.
- Cov phab ntsa tsis sib xws.
Kev daws:
Nce tuav siab; ncua sij hawm tuav.
- Tsim nyog nce txhaj tshuaj.
- Ua kom lub rooj vag loj.
- Tsim nyog txo lub melt kub.
- Tsim cov khoom lag luam nrog cov phab ntsa tuab li ib txwm ua tau.
VI. Flash / Burrs
Phenomenon: Cov khoom dhau ntawm cov kab sib cais los yog ntxig.
Ua rau:
- Cov khoom kub yog siab dhau lawm, ua rau muaj zog fluidity.
- Kev txhaj tshuaj siab thiab / lossis kev txhaj tshuaj nrawm dhau lawm.
- Clamping quab yuam yog tsis txaus.
- Ntau dhau clearance nyob rau hauv lub pwm los ua ke.
- Overfilling.
Kev daws:
- Txo cov khoom kub.
- Txo qhov kev txhaj tshuaj siab thiab txhaj tshuaj ceev.
- Ua kom lub zog clamping.
- Hloov cov pwm kom txo qhov kev tshem tawm.
- Txo qhov txhaj tshuaj ntim.
VII. Warpage thiab Deformation
Phenomenon: dabtsi yog khoov, twisting, dimensional instability
Ua rau:
- Kev ua kom txias tsis sib xws; siab sab hauv
- Cov pwm kub tsis sib haum (pem hauv ntej vs.
- Tseem ceeb variations ntawm phab ntsa thickness; tsis sib xws shrinkage
- Kev txhaj tshuaj nrawm heev; hnyav molecular orientation
- Unbalanced ejection
Kev daws:
- Xyuas kom zoo pwm kub; ncua lub sijhawm txias
- Txo kev txhaj tshuaj nrawm kom txo qis kev ntxhov siab sab hauv
- Optimize cov khoom phab ntsa thickness
- Kho qhov ejection tshuav nyiaj li cas
- Rau PVC tawv, pwm kub tuaj yeem tsim nyog
VIII. Kev tawg, brittleness, thiab chipping
Phenomena: cracking thaum demolding, tawg thaum sib dhos, chipped ces kaum / ntug.
Ua rau:
- Rigid PVC yog inherently brittle.
- Kev ntxhov siab ntau dhau.
- Pwm kub tsawg dhau; txias yog ceev heev.
- Kev tshem tawm tsis sib xws; "ejection whitening" (stress whitening).
- Plasticizer cov ntsiab lus tsis txaus lossis tsis sib xws.
Kev daws:
- Nce pwm kub rau 30-50 degree.
- Txo kev txhaj tshuaj nrawm thiab txo qis kev ntxhov siab.
- Kho cov ejector pins kom nce qhov ejection contact cheeb tsam.
- Tsim nyog nce qhov kev faib ua feem ntawm plasticizer (rau cov qib hloov tau).
- Tsis txhob txias dhau.
IX. Nto Fogging, tsis zoo gloss, thiab oily residue
Phenomena: deg haziness, tsis muaj gloss, greasy xav, blooming (frosting).
Ua rau:
- Kev tsiv teb tsaws (exudation) ntawm plasticizers lossis lubricants.
- Cov khoom kub tsawg dhau, ua rau cov yas tsis zoo.
- Pwm kub tsawg dhau.
- Rough pwm nto tiav.
- Kev sib xyaw tsis sib xws ntawm cov khoom siv raw.
Kev daws:
- Tswj qhov kev faib ua feem ntawm cov additives kom tsis txhob dhau.
- Tsim nyog nce cov khoom kub kom txhim kho plasticization.
- Ua kom pwm kub.
- Polish lub pwm nto.
- Xyuas kom meej sib xyaw ntawm cov khoom ua ntej pib tsim khoom.
X. Npuas thiab Voids
Phenomenon: npuas los yog voids tam sim no nyob rau saum npoo los yog nyob rau hauv ib feem.
Ua rau:
- Moisture cov ntsiab lus hauv cov khoom siv raw.
- Cov khoom kub ntau dhau, ua rau decomposition thiab roj tsim.
- Kev txhaj tshuaj nrawm heev, ua rau huab cua nkag.
- Kev tuav tsis txaus, tiv thaiv kom zoo compaction.
- Shrinkage nyob rau hauv tuab- cov phab ntsa, tsim cov voids nqus tsev vacuum.
Kev daws:
- Qhuav cov khoom siv raw.
- Txo cov khoom kub kom tsis txhob decomposition.
- Siv qhov kev txhaj tshuaj qeeb qeeb thaum lub sij hawm pwm filling.
- Ua kom lub zog tuav.
- Rau tuab- cov phab ntsa, txuas lub sijhawm tuav thiab txias.
