Mhando dzepurasitiki mukuumbwa kweiyo thermoplastic, nekuda kwekushanduka kwevhoriyamu kunokonzerwa nekristalllization, kusimba kwemukati kushushikana, kwakakura kusara kunetseka kwakaomeswa nechando muchikamu chepurasitiki, yakasimba mamolecular orientation uye zvimwe zvinhu, zvichienzaniswa ne thermosetting mapurasitiki, iyo shrinkage rate yakakura, iyo shrinkage range yakafara, uye directionality iri pachena. Pamusoro pezvo, iyo shrinkage Iyo shrinkage mushure mekuvhara kana humidity yekudzora kurapwa kazhinji yakakura kupfuura iyo thermosetting mapurasitiki.

Kana chikamu chepurasitiki chaumbwa, zvinhu zvakanyungudutswa zvinobata pamusoro pegomba, uye kunze kwemukati kunotonhora kuumba goko rakadzika-density yakasimba. Nekuda kwehurombo hwekupisa kwepurasitiki, chikamu chemukati chezvikamu zvepurasitiki chinotonhora zvishoma nezvishoma kuita dhizaini yakasimba yakasimba ine shrinkage yakakura. Naizvozvo, ukobvu hwemadziro, kutonhora kunononoka uye yakakwirira-density layer ukobvu inoderera zvakanyanya. Mukuwedzera, kuvapo kana kusavapo kwekuisa, kurongeka uye kuwanda kwekuisa kunokanganisa zvakananga kuyerera kwezvinhu, density kugovera uye shrinkage kuramba, saka hunhu hwezvikamu zvepurasitiki zvine simba guru pakukura uye kutungamira.
Iyo fomu, saizi uye kugoverwa kweiyo feed inlet inokanganisa zvakananga kuyerera kwezvinhu, density kugovera, kumanikidza kuchengetedza uye kudyisa maitiro uye kugadzira nguva. Kana chikamu chechiteshi chekudya chakananga uye chiteshi chekudya chakakura (kunyanya kana chikamu chakakora), shrinkage idiki asi kutungamira kwakakura, uye kana hupamhi nekureba kwechiteshi chekudya kuri kupfupi, kutungamira kuri kudiki. . Kana iri padyo nechiteshi chekudya kana kuenderana negwara rekuyerera kwezvinhu, iyo shrinkage yakakura.
Molding mamiriro: yakakwirira mold tembiricha, kunonoka kutonhora kwezvinhu zvakanyungudutswa, high density uye yakakura shrinkage. Kunyanya kune crystalline zvinhu, iyo shrinkage yakakura nekuda kwepamusoro crystallinity uye yakakura vhoriyamu shanduko. Iyo mold tembiricha yekugovera inoenderanawo nemukati uye kunze kutonhora kwezvikamu zvepurasitiki uye kufanana kwe density, iyo inokanganisa zvakananga saizi uye kutungamira kwekuderera kwechikamu chimwe nechimwe. Pamusoro pezvo, kubata kudzvanywa uye nguva zvakare zvine simba guru pakusunga. Avo vane dzvinyiriro huru uye nguva refu vane diki diki diki asi gwara rakakura.
Iyo jekiseni yekumanikidza yakakwira, iyo viscosity mutsauko wezvakanyungudutswa idiki, iyo interlayer shear stress idiki, uye elastic rebound mushure mekudhirowa yakakura, saka shrinkage inogona zvakare kuderedzwa zvakakodzera. Iyo tembiricha yezvinhu yakakwira, iyo shrinkage yakakura, asi iyo nzira idiki. Naizvozvo, iyo shrinkage yezvikamu zvepurasitiki zvinogona zvakare kushandurwa nenzira kwayo nekugadzirisa tembiricha yekuumbwa, kudzvanywa, kumhanya kwejekiseni uye nguva yekutonhora.
Munguva yekugadzira mold, shrinkage rate yechikamu chimwe nechimwe chechikamu chepurasitiki ichatemwa zvichienderana neruzivo maererano nehupamhi hwemapurasitiki akasiyana-siyana, kukora kwemadziro uye chimiro chezvikamu zvepurasitiki, fomu, saizi uye kugovera kwekudya, uye ipapo gomba. saizi ichaverengerwa. Kune yakakwirira-chaiyo zvikamu zvepurasitiki uye kana zvichinetsa kugona kudzika, nzira dzinotevera dzinofanirwa kushandiswa kugadzira mold:
① Iyo fomu, saizi uye yekugadzira mamiriro egating system inotemerwa nekuumbwa bvunzo.
② Saizi yekuchinja kwezvikamu zvepurasitiki kuti zvigadziriswe zvinogadziriswa mushure mekurapwa (chiyero chinofanira kunge chiri maawa makumi maviri nemana mushure mekudhirowa).
③ Rongedza kufa zvinoenderana nekuderera chaiko.
④ Edza mold zvakare, uye shandura mamiriro ekuita nenzira kwayo, uye shandura zvishoma kukosha kwe shrinkage kuti isangane nezvinodiwa zvezvikamu zvepurasitiki.
The fluidity of thermoplastics inogona kazhinji kuongororwa kubva munhevedzano ye indexes senge molecular weight, melt index, Archimedean spiral flow length, inooneka viscosity uye kuyerera reshiyo (process urefu / plastiki chikamu madziro ukobvu).
Kana huremu hwemamorekuru huri diki, huremu hwemamorekuru hwakakura, chimiro chemolecular chimiro chakashata, iyo melt index yakakwira, iyo screw yekuyerera kureba, iyo inooneka viscosity idiki, uye chiyero chekuyerera yakakura, fluidity kugona. Kune mapurasitiki ane zita rechigadzirwa chimwe chete, mirairo inofanirwa kuongororwa kuti ione kana kunyungudika kwayo kwakakodzera kuumbwa kwejekiseni. Zvinoenderana nezvinodiwa zvekugadzira mold, iyo fluidity yemapurasitiki akajairika inogona kukamurwa kuita zvikamu zvitatu:
① Yakanaka fluidity PA, PE. , PS, PP, CA, poly (4) methylene:
② Polystyrene series resins ine medium fluidity (yakadai seABS, se), PMMA, POM uye polyphenylene ether;
③ Yakashata fluidity PC, yakaoma PVC, polyphenylene ether, polysulfone, fluoroplastics.
Iyo fluidity yemapurasitiki akasiyana zvakare inoshanduka nekuda kweakasiyana ekuumba zvinhu. Zvinonyanya kupesvedzera zvinhu ndezvizvi zvinotevera:
① Kana tembiricha yakakwira, kuyerera kunowedzera, asi mapurasitiki akasiyana anewo misiyano. The fluidity yePS (kunyanya avo vane high impact resistance uye MFR value), PP, PA, PMMA, modified polystyrene (yakadai seABS, as), PC, Ca uye mamwe mapurasitiki anoshanduka zvikuru nekushisa. Kune PE, POM uye, kuwedzera kana kuderera kwekushisa kune zvishoma zvinokanganisa kuyerera kwavo. Naizvozvo, iyo yekutanga inofanirwa kugadzirisa tembiricha kudzora fluidity.
② Nekuwedzera kwekumanikidzwa kwejekiseni, zvinhu zvakanyungudutswa zvichaveurwa zvakanyanya uye kunyungudika kuchawedzerawo, kunyanya PE nePOM zvakanyanya kunzwisiswa, saka iyo jekiseni yekumanikidza inofanirwa kugadziridzwa kudzora fluidity panguva yekuumbwa.
③ Mold chimiro, gating system fomu, saizi, dhizaini, kutonhora sisitimu dhizaini, yakanyungudutswa kuyerera kuyerera (senge kupedzisa kwepamusoro, zvinhu chiteshi chikamu ukobvu, mhango chimiro, exhaust system) uye zvimwe zvinhu zvinokanganisa zvakananga kuyerera chaiko kwezvinhu zvakanyungudutswa mu mhango. Kana iyo yakanyungudutswa yakakurudzirwa kuderedza tembiricha uye kuwedzera fluidity kuramba, iyo fluidity inoderedzwa.
Chimiro chinonzwisisika chichasarudzwa maererano nekuyerera kwepurasitiki inoshandiswa mukugadzira mold. Munguva yekuumbwa, tembiricha yemidziyo, tembiricha yekuumbwa, kudzvanywa kwejekiseni, kumhanya kwejekiseni uye zvimwe zvinhu zvinogona zvakare kudzorwa kuti igadzirise zvakanaka mamiriro ekuzadza kuti asangane nezvinodiwa zvekuumba.
Crystalline thermoplastics inogona kukamurwa kuita crystalline mapurasitiki uye amorphous (anozivikanwawo seamorphous) mapurasitiki. Iyo inonzi crystallization phenomenon chiitiko chekuti mamorekuru anofamba akazvimiririra uye akazara munzvimbo isina kugadzikana kubva pakunyunguduka kuenda kune condensation mamiriro emapurasitiki, uye inova chiitiko chekuti mamorekuru anomira kufamba akasununguka, anodzvanya chinzvimbo chakamisikidzwa zvishoma, uye ane. tsika yekuita kuti hurongwa hwema molecular ive muenzaniso wemazuva ose.
Sechimiro chechimiro chekutonga marudzi maviri aya emapurasitiki, inogona kutariswa nekubuda pachena kwemadziro akakora epurasitiki zvikamu zvepurasitiki. Kazhinji, makristasi emidziyo ane opaque kana translucent (senge POM), uye amorphous zvinhu zviri pachena (senge PMMA). Zvisinei, pane zvisizvo. Semuenzaniso, poly (4) methylene ipurasitiki yekristaro ine kujeka kwepamusoro, uye ABS ndeye amorphous zvinhu asi isiri pachena.
Zvinotevera zvinodikanwa uye zvekuchengetedza mapurasitiki ekristaro zvichacherechedzwa panguva yekugadzira mold uye kusarudzwa kwejekiseni rekugadzira muchina:
① Kupisa kwakawanda kunodiwa kuti tembiricha yemidziyo ikwire kusvika kune tembiricha yekugadzira, saka zvishandiso zvine hombe yeplasticizing inofanira kushandiswa.
② Kupisa kunoburitswa panguva yekutonhodza uye kudzokorodza kwakakura, saka kunofanirwa kunyatsotonhorera.
③ Iyo chaiyo giravhiti mutsauko pakati peyakanyungudutswa uye yakasimba nyika yakakura, iyo yekuumba shrinkage yakakura, uye shrinkage uye porosity zviri nyore kuitika.
④ Kukurumidza kutonhora, yakaderera crystallinity, diki shrinkage uye yakakwirira pachena. Iyo crystallinity inoenderana nemadziro emadziro echikamu chepurasitiki. Ukobvu hwemadziro hune zvakanakira kutonhora kunononoka, yakakwirira crystallinity, yakakura shrinkage uye yakanaka yemuviri zvinhu. Naizvozvo, tembiricha yekuumbwa yecrystalline zvinhu zvinofanirwa kudzorwa sezvinodiwa.
⑤ Yakakosha anisotropy uye kushushikana kukuru kwemukati. Mushure mekudhirowa, iwo asina kucheneswa mamorekuru anowanzo kuenderera mberi nekupenya, ari mune simba kusaenzana, uye anowanzo chinja uye warpage.
⑥ Iyo crystallization tembiricha yemhando yakatetepa, uye zviri nyore kupinza zvinhu zvisina kunyungudika mufa kana kuvharira inopinza yekudya.
Heat senitivity inoreva maitiro ekushanduka kwemavara, kuderedzwa uye kuparara kwemamwe mapurasitiki anonyanya kunzwa kupisa. Pavanenge vachipisa kwenguva yakareba pakupisa kwepamusoro kana chikamu chekudya chekudya chinenge chiduku uye shear effect yakakura, kutonhora kwezvinhu kunowedzera. Mapurasitiki ane chimiro ichi anonzi mapurasitiki anopisa.
Zvakadai sePVC yakaoma, polyvinylidene chloride, vinyl acetate copolymer, POM, polytrichlorethylene fluoride, etc. Thermal sensitive plastics inogadzira monomer, gasi, yakasimba uye mamwe ma-products panguva yekuora, kunyanya mamwe magasi ekuora ane kukurudzira, kuora kana huturu kumuviri womunhu, midziyo uye molds. Naizvozvo, kutarisisa kunofanirwa kubhadharwa kune mold dhizaini, kusarudzwa kwejekiseni molding muchina uye kuumba. Screw injection molding machine inofanira kusarudzwa. Chikamu chegating system chinofanira kunge chakakura. Iyo mold uye dhiramu zvinofanirwa kuve chrome zvakaputirwa pasina angular stagnation. Iyo tembiricha yekuumba inofanira kunyatsodzorwa uye stabilizer inofanirwa kuwedzerwa kupurasitiki kuti iite zinyekenyeke yekupisa kwayo.
Kunyange kana mamwe mapurasitiki (akadai sePC) ane mvura shoma, inoora pasi pekushisa kwepamusoro uye kudzvinyirira kukuru. Iyi pfuma inonzi nyore hydrolysis, iyo inofanirwa kupiswa uye kuomeswa pamberi.
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