By Andy daga masana'antar Baiyear
An sabunta ta Nuwamba 5, 2022
1. Yawan raguwa
Siffai da lissafin thermoplastic molding shrinkage Kamar yadda aka ambata a sama, abubuwan da suka shafi raguwar gyare-gyaren thermoplastic sune kamar haka:
1.1 Filastik iri A lokacin aiwatar da gyare-gyare na thermoplastics, saboda canjin ƙarar da ke haifar da crystallization, matsanancin damuwa na ciki, babban damuwa da aka daskare a cikin ɓangaren filastik, da kuma daidaitawar kwayoyin halitta, ƙimar raguwa ya fi na filastik thermosetting.Bugu da kari, raguwar bayan gyare-gyaren, raguwar bayan annealing ko yanayin yanayin zafi gabaɗaya ya fi na robobi na thermosetting girma.
1.2 Halayen sassan filastik Lokacin da narkakkar kayan ya tuntuɓi saman rami, Layer na waje ya yi sanyi nan da nan ya zama harsashi mai ƙarancin ƙima.Saboda rashin ƙarancin zafin jiki na filastik, ɓangaren ciki na ɓangaren filastik yana sanyaya sannu a hankali don samar da ƙaƙƙarfan ƙaƙƙarfan ƙaƙƙarfan ƙaƙƙarfan ƙaƙƙarfan ƙaƙƙarfan ƙaƙƙarfan ƙanƙara.Saboda haka, kaurin bango, jinkirin sanyaya, da babban kauri mai yawa zai ragu sosai.Bugu da ƙari, kasancewar ko rashi na abubuwan da aka saka da kuma shimfidawa da yawan adadin abubuwan da aka sanyawa kai tsaye suna shafar jagorancin kwararar kayan aiki, rarrabawa da yawa da juriya na raguwa, don haka halaye na sassan filastik suna da tasiri mafi girma akan girman da jagorancin shrinkage.
1.3 Abubuwa irin su nau'i, girman da rarraba mashigar abinci kai tsaye suna shafar jagorancin kwararar kayan aiki, rarraba mai yawa, ciyar da matsa lamba da lokacin gyare-gyare.Tashar ciyarwa ta kai tsaye da tashar ciyarwa tare da babban ɓangaren giciye (musamman maɗaukaki na giciye) suna da ƙananan raguwa amma babban shugabanci, kuma faɗaɗɗen tashar ciyarwa yana da ƙananan jagora.Kusa da tashar ciyarwa ko a layi daya zuwa jagorancin kayan aiki, raguwa yana da girma.
1.4 Yanayin yanayin zafin jiki da molten abu yayi sanyi a hankali, da yawa yana da girma, musamman don kayan crystalline ya fi girma saboda babban adadin canji.Rarraba zafin jiki na mold kuma yana da alaƙa da sanyaya na ciki da na waje da daidaituwar daidaituwa na ɓangaren filastik, wanda ke shafar kai tsaye.
Yana rinjayar girman da shugabanci na shrinkage kowane bangare.Bugu da ƙari, matsi na riƙewa da lokaci kuma suna da tasiri mai girma akan ƙaddamarwa, ƙaddamarwa yana da ƙananan amma shugabanci yana da girma lokacin da matsa lamba ya yi girma kuma lokaci ya yi tsawo.Matsakaicin allurar yana da girma, bambancin danko na kayan da aka narkar da shi kadan ne, danniya mai karfi na interlayer yana da karami, kuma sake dawowa bayan rushewa yana da girma, don haka za'a iya rage raguwa da kyau, yawan zafin jiki na abu yana da girma, raguwa yana da girma. , amma shugabanci karami ne.Sabili da haka, daidaita yanayin ƙirar ƙira, matsa lamba, saurin allura da lokacin sanyaya da sauran abubuwan yayin gyare-gyaren kuma na iya canza raguwar ɓangaren filastik daidai.
Lokacin zayyana mold, bisa ga shrinkage kewayon daban-daban robobi, da bango kauri da kuma siffar da filastik part, da tsari, girma da kuma rarraba tashar jiragen ruwa, da shrinkage kudi na kowane bangare na filastik part an ƙaddara ta gwaninta. sannan ana lissafin girman kogon.Don ɓangarorin filastik madaidaici kuma lokacin da yake da wahala a iya sarrafa ƙimar raguwa, yakamata a yi amfani da hanyoyin masu zuwa don tsara ƙirar:
① Ɗauki ƙarami na raguwa don diamita na waje na sassan filastik, da kuma mafi girman raguwa don diamita na ciki, don barin dakin don gyara bayan gwajin mold.
② Gwajin ƙira yana ƙayyade tsari, girman da yanayin gyare-gyare na tsarin gating.
③ Ana aiwatar da sassan filastik da za a sarrafa su bayan sarrafa su don tantance canjin girma (dole ne a yi ma'aunin bayan sa'o'i 24 bayan ƙaddamarwa).
④ Gyara mold bisa ga ainihin raguwa.
⑤ Sake gwada mold kuma canza yanayin tsari don ɗan canza ƙimar raguwa don saduwa da buƙatun sassan filastik.
2. Ruwa
2.1 Za'a iya yin nazari akan yawan ruwa na thermoplastics gabaɗaya daga jerin fihirisa kamar nauyin kwayoyin halitta, narke index, Archimedes karkace kwarara kwarara, fili danko da kwarara rabo (tsari Tsari / filastik kauri kauri).Ƙananan nau'in kwayoyin halitta, rarraba nauyin nauyin kwayoyin halitta, ƙarancin tsarin kwayoyin halitta na yau da kullum, babban narke index, tsayin karkace mai tsayi, ƙananan danko na fili, da babban rabo mai gudana, ruwa yana da kyau.a cikin gyare-gyaren allura.Dangane da buƙatun ƙirar ƙira, yawan ruwan robobin da ake amfani da su na yau da kullun na iya kasu kashi uku:
① Kyakkyawan ruwa mai kyau PA, PE, PS, PP, CA, poly (4) methyl pentylene;
②Polystyrene jerin guduro (kamar ABS, AS), PMMA, POM, polyphenylene ether tare da matsakaicin ruwa;
③Poor fluidity PC, wuya PVC, polyphenylene ether, polysulfone, polyarylsulfone, fluoroplastic.
2.2 Ruwan robobi daban-daban shima yana canzawa saboda abubuwan gyare-gyare daban-daban.Babban abubuwan da ke tasiri sune kamar haka:
① Mafi girma da yawan zafin jiki, mafi girma da fluidity na kayan, amma daban-daban robobi ma daban-daban, PS (musamman tasiri-resistant da high MFR darajar), PP, PA, PMMA, modified polystyrene (kamar ABS, AS) , PC, CA da sauran robobi ruwa ya bambanta sosai da zafin jiki.Don PE, POM, haɓakar zafin jiki ko raguwa yana da ɗan tasiri akan ruwan sa.Sabili da haka, tsohon ya kamata ya daidaita zafin jiki don sarrafa ruwa yayin gyare-gyare.
②Lokacin da matsa lamba na allura ya karu, kayan da aka narkar da su za su yi shear sosai, kuma ruwa zai karu, musamman ma PE da POM sun fi damuwa, don haka ya kamata a daidaita matsa lamba don sarrafa ruwa yayin gyare-gyare.
③ Siffar, girman, shimfidar wuri, ƙirar tsarin sanyaya, juriya mai gudana na narkakkar kayan (kamar ƙarewar ƙasa, kauri na sashin gaba, siffar rami, tsarin shayewa) da sauran abubuwan kai tsaye suna shafar kwararar kayan narkakkar a cikin rami.Haƙiƙanin ruwa a cikin ciki, idan an saukar da zafin jiki na narkakken abu kuma an ƙara juriya na ruwa, ruwan zai ragu.Lokacin zayyana ƙira, ya kamata a zaɓi tsarin da ya dace bisa ga yawan ruwan filastik da aka yi amfani da shi.A lokacin gyare-gyaren, zafin kayan abu, zazzabi mai ƙira, matsa lamba na allura, saurin allura da sauran dalilai kuma ana iya sarrafa su don daidaita yanayin cikawa yadda ya kamata don biyan buƙatun gyare-gyare.
3. Crystallinity
Thermoplastics za a iya raba kashi biyu: crystalline robobi da kuma non-crystalline (wanda aka sani da amorphous) robobi bisa ga rashin crystallization a lokacin condensation.
Abun da ake kira crystallization al'amarin shine, lokacin da filastik ya canza daga narkakkar yanayi zuwa narke, kwayoyin suna motsawa da kansu, gaba daya a cikin yanayin rashin lafiya, kuma kwayoyin suna daina motsawa cikin 'yanci, bisa ga wani ɗan gajeren matsayi, kuma akwai hali. don yin tsarin kwayoyin halitta samfurin al'ada.wani sabon abu.
A matsayin ma'auni don yin la'akari da bayyanar waɗannan nau'ikan robobi guda biyu, ya dogara da gaskiyar sassan filastik mai kauri mai kauri na filastik.Gabaɗaya, kayan lu'ulu'u ba su da kyau ko kuma masu jujjuyawa (kamar POM, da dai sauransu), kuma kayan amorphous suna bayyana (kamar PMMA, da sauransu).Amma akwai keɓancewa, irin su poly (4) methyl pentylene robobi ne na crystalline amma yana da babban fa'ida, ABS abu ne mai amorphous amma ba bayyananne ba.
Lokacin zayyana ƙirar ƙira da zaɓin injin gyare-gyaren allura, ya kamata a lura da buƙatu masu zuwa da matakan kariya don robobin crystalline:
① Zafin da ake buƙata don zafin jiki na kayan abu ya tashi zuwa zafin jiki na gyare-gyare yana da girma, kuma kayan aiki tare da babban ƙarfin filastik ya kamata a yi amfani da su.
②Zafin da aka saki yayin sanyaya yana da girma, don haka ya kamata a sanyaya sosai.
③ Bambancin ƙayyadaddun nauyi tsakanin narkakkar yanayi da ƙaƙƙarfan yanayi babba ne, ƙaƙƙarfan gyare-gyaren yana da girma, kuma ramukan raguwa da pores suna da yuwuwar faruwa.
④ Saurin sanyaya, ƙananan crystallinity, ƙananan raguwa da babban nuna gaskiya.Ƙa'idar tana da alaƙa da kauri na bango na ɓangaren filastik, bangon bango yana jinkirin sanyaya, crystallinity yana da girma, raguwa yana da girma, kuma kayan jiki suna da kyau.Sabili da haka, kayan kristal ya kamata su sarrafa zafin jiki kamar yadda ake buƙata.
⑤ Muhimmancin anisotropy da babban damuwa na ciki.Bayan rushewa, kwayoyin da ba a yi su ba suna ci gaba da yin kyalkyali kuma suna cikin yanayin rashin daidaituwar makamashi, wanda ke da wuyar lalacewa da kuma yaƙe-yaƙe.
⑥ Matsakaicin zafin jiki na crystallization yana da kunkuntar, kuma yana da sauƙi don allurar kayan da ba a narkewa ba a cikin ƙirar ko toshe tashar ciyarwa.
4. Robobi masu zafin zafi da robobi masu sauƙin ruwa
4.1 Thermal sensitivity yana nufin cewa wasu robobi sun fi kula da zafi, kuma lokacin dumama yana da tsawo a babban zafin jiki ko ɓangaren ɓangaren tashar ciyarwa ya yi ƙanƙara, kuma lokacin da aikin shear ya yi girma, yawan zafin jiki yana ƙaruwa kuma yana da wuyar gaske. zuwa canza launi, lalacewa, da bazuwar.Yana da wannan sifa.robobi ana kiran su robobi masu zafin zafi.Irin su m PVC, polyvinylidene chloride, vinyl acetate copolymer, POM, polychlorotrifluoroethylene, da dai sauransu. Lokacin da robobi masu zafi suka lalace, ana haifar da samfurori irin su monomers, gas, da daskararru, musamman ma wasu gurɓatattun iskar gas suna da ban tsoro, masu lalata ko masu guba. zuwa jikin mutum, kayan aiki da kyawon tsayuwa.Saboda haka, ya kamata a biya hankali ga ƙirar ƙira, zaɓin injunan gyare-gyaren allura da gyare-gyare.Ya kamata a zaɓi injunan gyare-gyaren allura.Sashin giciye na tsarin gating ya kamata ya zama babba.Mold da ganga ya kamata su kasance masu chrome-plated, kuma kada a sami sasanninta.Ƙara stabilizer don raunana kaddarorin sa masu zafi.
4.2 Ko da wasu robobi (irin su PC) suna ɗauke da ɗan ƙaramin ruwa, za su ruɓe a cikin matsanancin zafin jiki da matsa lamba.Ana kiran wannan dukiya mai sauƙi hydrolysis, wanda dole ne a yi zafi kuma a bushe a gaba.
5. Danniya fatattaka da narkewa karaya
5.1 Wasu robobi suna da damuwa ga damuwa, kuma suna da wuyar samun damuwa na ciki yayin gyare-gyaren kuma suna da karye kuma suna da sauƙin fashe.Sassan filastik za su fashe a ƙarƙashin aikin ƙarfin waje ko sauran ƙarfi.Don wannan, ban da ƙara abubuwan da ke daɗaɗawa ga albarkatun ƙasa don haɓaka juriya, ya kamata a ba da hankali ga bushewar albarkatun ƙasa, kuma ya kamata a zaɓi yanayin gyare-gyaren da kyau don rage damuwa na ciki da haɓaka juriya.Ya kamata a zaɓi madaidaicin siffa na sassa na filastik, kuma matakan kamar abubuwan da ake sakawa bai kamata a saita su don rage girman damuwa ba.Lokacin zayyana gyaggyarawa, ya kamata a ƙãra gangaren rushewa, kuma ya kamata a zaɓi tashar ciyarwa mai dacewa da hanyar fitarwa.A lokacin gyare-gyaren, zafin kayan abu, zafin jiki, matsa lamba na allura da lokacin sanyaya ya kamata a daidaita su yadda ya kamata don kauce wa rushewa lokacin da sassan filastik suka yi sanyi da kuma gatsewa., Bayan yin gyare-gyaren, sassan filastik kuma ya kamata a bi da su a baya don inganta juriya na tsagewa, kawar da damuwa na ciki da kuma hana haɗuwa da kaushi.
5.2 Lokacin da polymer narke tare da wani narke kwarara kudi wuce ta cikin bututun ƙarfe rami a akai zazzabi da ta kwarara kudi wuce wani darajar, bayyananne m fasa a kan narke surface ake kira narkewa karaya, wanda zai lalata bayyanar da jiki Properties na. sassan filastik.Sabili da haka, lokacin da zaɓin polymers tare da ƙimar narke mai girma, da dai sauransu, ya kamata a ƙara sashin giciye na bututun ƙarfe, mai gudu, da tashar abinci, ya kamata a rage saurin allura, kuma ya kamata a ƙara yawan zafin jiki.
6. Thermal yi da kuma sanyaya kudi
6.1 Robobi daban-daban suna da kaddarorin thermal daban-daban kamar takamaiman zafi, ƙayyadaddun yanayin zafi da nakasar zafi.Lokacin yin filastik tare da ƙayyadaddun zafi mai zafi, ana buƙatar babban adadin zafi, kuma ya kamata a zaɓi na'ura mai gyare-gyaren allura tare da babban ƙarfin filastik.Lokacin sanyaya na filastik tare da zafin zafi mai zafi na iya zama ɗan gajeren lokaci kuma ƙaddamarwa yana da wuri, amma ya kamata a hana nakasar sanyaya bayan rushewa.Filastik tare da ƙananan ƙarancin zafin jiki suna da jinkirin sanyaya (kamar ionic polymers, da dai sauransu), don haka dole ne a sanyaya su gabaɗaya, kuma dole ne a ƙarfafa tasirin sanyaya.Motoci masu zafi masu zafi sun dace da robobi tare da ƙarancin ƙayyadaddun ƙayyadaddun zafi da haɓakar haɓakar thermal.Filastik tare da ƙayyadaddun zafi mai ƙayyadaddun ƙayyadaddun yanayin zafi, ƙarancin ƙarancin yanayin zafi da ƙarancin sanyi ba su dace da gyare-gyare mai sauri ba, kuma dole ne a zaɓi injunan gyare-gyaren allura masu dacewa kuma dole ne a ƙarfafa sanyaya.
6.2 Ana buƙatar robobi daban-daban don kula da ƙimar sanyi mai dacewa bisa ga nau'ikan su da halaye da siffar sassan filastik.Sabili da haka, dole ne a saita ƙirar tare da tsarin dumama da sanyaya bisa ga buƙatun gyare-gyare don kula da wani zazzabi mai ƙima.Lokacin da yawan zafin jiki na kayan yana ƙara yawan zafin jiki, ya kamata a sanyaya don hana sassan filastik daga lalacewa bayan lalatawa, rage zagayowar gyare-gyare, da rage crystallinity.Lokacin da zafin daɗaɗɗen filastik bai isa ba don kiyaye ƙirar a wani zafin jiki, ƙirar ya kamata a sanye shi da tsarin dumama don kiyaye ƙirar a wani zafin jiki don sarrafa ƙimar sanyaya, tabbatar da ruwa, inganta yanayin cikawa ko sarrafa filastik. sassa don yin sanyi a hankali.Hana sanyi mara daidaituwa a ciki da wajen sassa na filastik mai kauri mai kauri da haɓaka crystallinity.Ga waɗanda ke da ruwa mai kyau, babban wurin gyare-gyare da kuma yanayin zafin kayan da bai dace ba, bisa ga yanayin gyare-gyaren sassa na filastik, ana amfani da dumama ko sanyaya a wani lokaci ko kuma ana amfani da dumama da sanyaya tare.Don wannan dalili, ƙirar ya kamata a sanye shi da tsarin sanyaya mai dacewa ko tsarin dumama.
Lokacin aikawa: Nuwamba-29-2022
