骨輪零件的注射模設(shè)計(jì)【圓形線圈骨架】【一模兩腔】【側(cè)抽芯】【說(shuō)明書(shū)+CAD】
購(gòu)買(mǎi)設(shè)計(jì)請(qǐng)充值后下載,資源目錄下的文件所見(jiàn)即所得,都可以點(diǎn)開(kāi)預(yù)覽,資料完整,充值下載可得到資源目錄里的所有文件。【注】:dwg后綴為CAD圖紙,doc,docx為WORD文檔,原稿無(wú)水印,可編輯。具體請(qǐng)見(jiàn)文件預(yù)覽,有不明白之處,可咨詢QQ:12401814
南京理工大學(xué)泰州科技學(xué)院學(xué)生畢業(yè)設(shè)計(jì)(論文)中期檢查表學(xué)生姓名學(xué) 號(hào)指導(dǎo)教師選題情況課題名稱(chēng)骨輪零件的注射模設(shè)計(jì)難易程度偏難適中偏易工作量較大合理較小符合規(guī)范化的要求任務(wù)書(shū)有無(wú)開(kāi)題報(bào)告有無(wú)外文翻譯質(zhì)量?jī)?yōu)良中差學(xué)習(xí)態(tài)度、出勤情況好一般差工作進(jìn)度快按計(jì)劃進(jìn)行慢中期工作匯報(bào)及解答問(wèn)題情況優(yōu)良中差中期成績(jī)?cè)u(píng)定:良所在專(zhuān)業(yè)意見(jiàn):進(jìn)度一般 負(fù)責(zé)人: 年 月 日 南京理工大學(xué)泰州科技學(xué)院畢業(yè)設(shè)計(jì)(論文)開(kāi)題報(bào)告學(xué) 生 姓 名:學(xué) 號(hào):專(zhuān) 業(yè):機(jī)械工程及自動(dòng)化設(shè)計(jì)(論文)題目:骨輪零件的注射模設(shè)計(jì)指 導(dǎo) 教 師: 2009 年 3 月 15 日開(kāi)題報(bào)告填寫(xiě)要求1開(kāi)題報(bào)告(含“文獻(xiàn)綜述”)作為畢業(yè)設(shè)計(jì)(論文)答辯委員會(huì)對(duì)學(xué)生答辯資格審查的依據(jù)材料之一。此報(bào)告應(yīng)在指導(dǎo)教師指導(dǎo)下,由學(xué)生在畢業(yè)設(shè)計(jì)(論文)工作前期內(nèi)完成,經(jīng)指導(dǎo)教師簽署意見(jiàn)及所在專(zhuān)業(yè)審查后生效;2開(kāi)題報(bào)告內(nèi)容必須用黑墨水筆工整書(shū)寫(xiě)或按教務(wù)處統(tǒng)一設(shè)計(jì)的電子文檔標(biāo)準(zhǔn)格式(可從教務(wù)處網(wǎng)頁(yè)上下載)打印,禁止打印在其它紙上后剪貼,完成后應(yīng)及時(shí)交給指導(dǎo)教師簽署意見(jiàn);3“文獻(xiàn)綜述”應(yīng)按論文的格式成文,并直接書(shū)寫(xiě)(或打?。┰诒鹃_(kāi)題報(bào)告第一欄目?jī)?nèi),學(xué)生寫(xiě)文獻(xiàn)綜述的參考文獻(xiàn)應(yīng)不少于15篇科技論文的信息量,一般一本參考書(shū)最多相當(dāng)于三篇科技論文的信息量(不包括辭典、手冊(cè));4有關(guān)年月日等日期的填寫(xiě),應(yīng)當(dāng)按照國(guó)標(biāo)GB/T 740894數(shù)據(jù)元和交換格式、信息交換、日期和時(shí)間表示法規(guī)定的要求,一律用阿拉伯?dāng)?shù)字書(shū)寫(xiě)。如“2009年3月15日”或“2009-03-15”。畢 業(yè) 設(shè) 計(jì)(論 文)開(kāi) 題 報(bào) 告1結(jié)合畢業(yè)設(shè)計(jì)(論文)課題情況,根據(jù)所查閱的文獻(xiàn)資料,每人撰寫(xiě)2000字左右的文獻(xiàn)綜述:文 獻(xiàn) 綜 述摘要 模具是工業(yè)生產(chǎn)的重要基礎(chǔ),模具工業(yè)已成為國(guó)家具有相當(dāng)規(guī)模和高技術(shù)行業(yè)特征的裝備產(chǎn)業(yè)。模具工業(yè)生產(chǎn)技術(shù)水平的高低,已成為衡量一個(gè)國(guó)家產(chǎn)品制造水平高低的重要標(biāo)志。介紹了有關(guān)塑料模具在我國(guó)模具工業(yè)中發(fā)展的一些概況。關(guān)鍵詞 塑料模具 CAD技術(shù) 設(shè)計(jì) 制造1 模具發(fā)展的現(xiàn)狀隨著機(jī)械工業(yè)(尤其是汽車(chē)、摩托車(chē)工業(yè))、電子工業(yè)(尤其是家電工業(yè))、航空工業(yè)、儀器儀表工業(yè)和日常用品工業(yè)的發(fā)展,塑件的需求量越來(lái)越多,質(zhì)量要求也越來(lái)越高,這就要求成型塑件的模具開(kāi)發(fā)、設(shè)計(jì)與制造的水平也必須越來(lái)越高1。近年來(lái),我國(guó)塑料模具業(yè)發(fā)展相當(dāng)快,塑料模具在整個(gè)模具行業(yè)中約占30%左右,而在整個(gè)塑料模具市場(chǎng)以注塑模具需求量最大2。時(shí)代潮流的發(fā)展急切地要求許多企業(yè)開(kāi)始追求提高產(chǎn)品質(zhì)量及生產(chǎn)效率,縮短設(shè)計(jì)周期及制造周期,降低生產(chǎn)成本,最大限度地提高模具制造業(yè)的應(yīng)變能力等等目標(biāo)。新興的模具CAD技術(shù)很大程度上實(shí)現(xiàn)了企業(yè)的愿望。近年來(lái),CAD技術(shù)的應(yīng)用越來(lái)越普遍和深入,大大縮短了模具設(shè)計(jì)周期,提高了制模質(zhì)量和復(fù)雜模具的制造能力3。目前,我國(guó)已普遍采用CAD技術(shù)等大型軟件,它的方便、快捷、實(shí)用已在實(shí)踐中得到證實(shí)。模具的CAD設(shè)計(jì)、分析,包括根據(jù)產(chǎn)品模型進(jìn)行模具分型面的設(shè)計(jì)、確定型腔和型芯、模具結(jié)構(gòu)的詳細(xì)設(shè)計(jì)、塑料充填過(guò)程分析等幾個(gè)方面。利用先進(jìn)的特征造型軟件如PRO/E、UGII等很容易地確定分型面,生成上下模腔和模芯,再進(jìn)行流道、澆口以及冷卻水管的布置等。確定了這些設(shè)計(jì)數(shù)據(jù)以后,再利用模具分析軟件(CAE),如Plastic Advisor、CFLOW進(jìn)行塑料的成形過(guò)程分析。根據(jù)Plastic Advisor軟件和它的豐富的材料、工藝數(shù)據(jù)庫(kù),通過(guò)輸入成形工藝參數(shù),可動(dòng)態(tài)仿真分析塑料在注塑模腔內(nèi)的注射過(guò)程流動(dòng)情況(含多澆口注射時(shí)的塑料匯流紋分析)、分析溫度壓力變化情況、分析注塑件殘余應(yīng)力等,根據(jù)分析情況來(lái)檢查模具結(jié)構(gòu)的合理性、流動(dòng)狀態(tài)的合理性、產(chǎn)品的質(zhì)量問(wèn)題等4。模具通過(guò)CAD設(shè)計(jì)和分析,就可以將錯(cuò)誤消除在設(shè)計(jì)階段,提高一次試模成功率。模具的計(jì)算機(jī)輔助制造(CAM)技術(shù)主要應(yīng)用在數(shù)控銑削加工、線切割加工、電火花加工等方面5。CAM技術(shù)尤其是在復(fù)雜模具的型腔、型芯及電極的銑削加工中起著更加重要的作用。利用模具技術(shù)在電腦上模仿機(jī)床的加工過(guò)程, 能直觀反映加工的結(jié)果,能直接評(píng)估加工后零件的質(zhì)量,能檢查出加工的錯(cuò)誤6。在檢查加工后零件的質(zhì)量時(shí),可在電腦上對(duì)加工后的實(shí)體模型進(jìn)行任意的剖切,直接測(cè)量其尺寸和精度。因此,它能把錯(cuò)誤消除在加工工藝編程設(shè)計(jì)階段,減少加工后的修補(bǔ)和返工,大大提高模具的制造效率和質(zhì)量7。綜上所述, 模具CAD集成技術(shù)就是應(yīng)用于模具制造各個(gè)環(huán)節(jié)的計(jì)算機(jī)輔助技術(shù)和實(shí)現(xiàn)各環(huán)節(jié)信息集成的技術(shù)8。2 模具工業(yè)的發(fā)展趨勢(shì)我國(guó)國(guó)民經(jīng)濟(jì)的高速發(fā)展對(duì)模具工業(yè)提出了越來(lái)越高的要求,預(yù)計(jì)到2010年,在建筑與建材行業(yè)方面,塑料門(mén)窗的普及率為30%,塑料管的普及率將達(dá)到50%,這些都會(huì)大大增大對(duì)模具的需求量9。21世紀(jì)模具行業(yè)的基本特征是高度集成化、智能化、柔性化和網(wǎng)絡(luò)化。追求的目標(biāo)是提高產(chǎn)品的質(zhì)量及生產(chǎn)效率,縮短設(shè)計(jì)及制造周期,降低生產(chǎn)成本,最大限度地提高模具行業(yè)的應(yīng)變能力,滿足用戶需要10??梢?jiàn),未來(lái)我國(guó)模具工業(yè)和技術(shù)的主要發(fā)展方向?qū)⑹牵?1) 大力普及、廣泛應(yīng)用CAD/CAE/CAM技術(shù),逐步走向集成化?,F(xiàn)代模具設(shè)計(jì)、制造不僅應(yīng)強(qiáng)調(diào)信息的集成,更應(yīng)該強(qiáng)調(diào)技術(shù)、人和管理的集成;(2) 提高大型、精密、復(fù)雜與長(zhǎng)壽命模具的設(shè)計(jì)與制造技術(shù),逐步減少模具的進(jìn)口量,增加模具的出口量;(3) 在塑料注射成型模具中,積極應(yīng)用熱流道,推廣氣輔或水輔注射成型,以及高壓注射成型技術(shù),滿足產(chǎn)品的成型需要;(4) 提高模具標(biāo)準(zhǔn)化水平和模具標(biāo)準(zhǔn)件的使用率。模具標(biāo)準(zhǔn)件是模具基礎(chǔ),其大量應(yīng)用可縮短模具設(shè)計(jì)制造周期,同時(shí)也顯著提高模具的制造精度和使用性能,大大地提高模具質(zhì)量。我國(guó)模具商品化、標(biāo)準(zhǔn)化率均低于30%,而先進(jìn)國(guó)家均高于70%,每年我們要從國(guó)外進(jìn)口相當(dāng)數(shù)量的模具標(biāo)準(zhǔn)件,其費(fèi)用約占年模具進(jìn)口額的3%8%;(5) 發(fā)展快速制造成型和快速制造模具,即快速成型制造技術(shù),迅速制造出產(chǎn)品的原型與模具,降低成本推向市場(chǎng);(6) 積極研究與開(kāi)發(fā)模具的拋光技術(shù)、設(shè)備與材料,滿足特殊產(chǎn)品的需要; (7) 推廣應(yīng)用高速銑削、超精度加工和復(fù)雜加工技術(shù)與工藝,滿足模具制造的需要;(8) 開(kāi)發(fā)優(yōu)質(zhì)模具材料和先進(jìn)的表面處理技術(shù),提高模具的可靠性;(9) 研究和應(yīng)用模具的高速測(cè)量技術(shù)、逆向工程與并行工程,最大限度地提高模具的開(kāi)發(fā)效率與成功率;(10) 開(kāi)發(fā)新的成型工藝與模具,以滿足未來(lái)的多學(xué)科多功能綜合產(chǎn)品開(kāi)發(fā)設(shè)計(jì)技術(shù)11。3 塑料模具發(fā)展的意義塑料具有密度小、質(zhì)量輕、絕緣性能好、耐磨耐腐蝕等特殊性能,已成為各行各業(yè)不可缺少的一種重要材料,其制品在工業(yè)生產(chǎn)中得到廣泛地應(yīng)用。特別是在計(jì)算機(jī)、辦公機(jī)器、照相機(jī)、汽車(chē)、儀器儀表、機(jī)械制造、交通、通信、輕工、建筑、日用品以及家用電器行業(yè)中得到廣泛使用,隨著納米塑料等新材料的出現(xiàn),今后塑料的應(yīng)用將會(huì)覆蓋國(guó)民經(jīng)濟(jì)的各個(gè)領(lǐng)域,尤其在國(guó)防和尖端科學(xué)技術(shù)領(lǐng)域中將占有越來(lái)越重要的地位。塑料產(chǎn)品從設(shè)計(jì)到成型生產(chǎn)是一個(gè)十分復(fù)雜的過(guò)程,它包括塑料制品設(shè)計(jì)、模具加工制造和塑件生產(chǎn)等幾個(gè)主要方面,它需要產(chǎn)品設(shè)計(jì)師、模具設(shè)計(jì)師、模具加工工藝師及熟練操作工人協(xié)同努力來(lái)完成,它是一個(gè)設(shè)計(jì)、修改、再設(shè)計(jì)的反復(fù)迭代,不斷優(yōu)化的過(guò)程。隨著塑料制品的應(yīng)用日漸廣泛,為塑料模具提供了一個(gè)廣闊的市場(chǎng),同時(shí)對(duì)模具也提出了更高的要求。模具又是“效益放大器”,用模具生產(chǎn)的最終產(chǎn)品的價(jià)值,往往是模具自身價(jià)值的幾十倍、上百倍。模具生產(chǎn)技術(shù)水平的高低,己成為衡量一個(gè)國(guó)家產(chǎn)品制造水平高低的重要標(biāo)志,在很大程度上決定著產(chǎn)品的質(zhì)量、企業(yè)的效益和新產(chǎn)品的開(kāi)發(fā)能力12。可以說(shuō),現(xiàn)代模具工業(yè)已經(jīng)確立了作為一門(mén)新興基礎(chǔ)性工業(yè)的地位,并且擁有越來(lái)越多的市場(chǎng)機(jī)遇。目前在工程塑料業(yè)中,80采用了注射成型13。近年來(lái)由于汽車(chē)、建筑、家用電器、食品、醫(yī)藥等產(chǎn)業(yè)對(duì)注射制品日益增長(zhǎng)的需要,推動(dòng)了注射成型技術(shù)水平的發(fā)展和提高從美國(guó)、日本、德國(guó)、意大利、加拿大等主要生產(chǎn)國(guó)來(lái)看,塑模的產(chǎn)量都在逐年增加,在塑料相關(guān)工業(yè)中占的比重最大。加入WTO以后,將對(duì)我國(guó)塑模行業(yè)的發(fā)展產(chǎn)生重大影響,對(duì)企業(yè)來(lái)說(shuō)機(jī)遇和挑戰(zhàn)并存?,F(xiàn)代先進(jìn)制造技術(shù)已在改變注塑模具領(lǐng)域的許多傳統(tǒng)觀念和生產(chǎn)組織方式,技術(shù)創(chuàng)新已成為21世紀(jì)企業(yè)競(jìng)爭(zhēng)的焦點(diǎn)。由于新技術(shù)的應(yīng)用和引導(dǎo),塑模技術(shù)在國(guó)民經(jīng)濟(jì)中的作用越來(lái)越大,在一定程度上決定了我國(guó)機(jī)械制造業(yè)在21世紀(jì)的市場(chǎng)競(jìng)爭(zhēng)力,為此我們要有足夠的認(rèn)識(shí)并采取得力的措施。這就要求我們積極推行專(zhuān)業(yè)化生產(chǎn),改變大而全、缺乏高、精、尖的弱勢(shì),積極研發(fā)高新塑模技術(shù),力爭(zhēng)走在行業(yè)前列,才能在行業(yè)競(jìng)爭(zhēng)中落于不敗之地。參 考 文 獻(xiàn) 1 郭新玲. 塑料模具設(shè)計(jì)M. 北京:清華大學(xué)出版社,2006.7.2 阮雪玉,等. 中國(guó)模具工業(yè)和技術(shù)的發(fā)展J. 模具技術(shù), 2001.2.3 于廣濱,金向陽(yáng),胥文,等. AutoCAD 2008機(jī)械制圖標(biāo)準(zhǔn)培訓(xùn)教程(中文版)M. 北京: 機(jī)械工業(yè)出版社,2008.5.4 曾珊琪,丁毅. 模具制造技術(shù)M. 北京:化學(xué)工業(yè)出版社,2008.5.5 林清安. Pro/ENGINEER零件設(shè)計(jì)(基礎(chǔ)篇上、下)M. 北京:北京大學(xué)出版社,2000.6 符朝興,焦洪宇. ProENGINEER Wildfire 3.0 三維機(jī)械設(shè)計(jì)M. 北京: 機(jī)械工業(yè)出版社,2008.1.7 肖景容,李德群,等. 模具計(jì)算機(jī)輔助設(shè)計(jì)與制造N. 北京:國(guó)防工業(yè)出版社,1992. 8 周驥平,林崗. 機(jī)械制造自動(dòng)化技術(shù)(第2版) M. 北京: 機(jī)械工業(yè)出版社,2007.2.9 黃毅宏.模具制造工藝M . 北京:機(jī)械工業(yè)出版社, 2003.10 高濟(jì).塑料模具設(shè)計(jì)M .北京: 機(jī)械工業(yè)出版社,2002.11 李德群. 塑性加工技術(shù)發(fā)展?fàn)顩r及趨勢(shì)J. 航空制造技術(shù), 2002.3.12 陳德生. 機(jī)械制造工藝學(xué)M. 杭州:浙江大學(xué)出版社,2007.1.13 梅伶. 模具課程設(shè)計(jì)指導(dǎo)M. 北京:機(jī)械工業(yè)出版社,2006.12.14 丁浩.塑料工業(yè)實(shí)用手冊(cè)M . 北京:化學(xué)工業(yè)出版社,200015 德 K.Stoeckhert/G.Menning. 模具制造手冊(cè)S. 北京:化學(xué)工業(yè)出版社,2003.1. 畢 業(yè) 設(shè) 計(jì)(論 文)開(kāi) 題 報(bào) 告本課題要研究或解決的問(wèn)題和擬采用的研究手段(途徑):1 研究?jī)?nèi)容本設(shè)計(jì)要求根據(jù)所給骨輪零件實(shí)物,使用Pro/Engineer、UG或Solid edge等大型CAD軟件測(cè)繪零件圖紙,設(shè)計(jì)一模兩腔的成型注射模具。骨輪是以回旋體結(jié)構(gòu)為主,中間通孔的零件,對(duì)于注塑模的設(shè)計(jì)比較簡(jiǎn)單,使用哈夫分型的設(shè)計(jì)方法就能設(shè)計(jì)出合理有效的注塑模具。骨輪的材料:聚甲醛(POM)。對(duì)于模具的設(shè)計(jì),首先對(duì)要制造的骨輪進(jìn)行測(cè)繪,再對(duì)尺寸進(jìn)行合理的圓整,然后利用ProE對(duì)骨輪進(jìn)行三維造型設(shè)計(jì)。2 研究手段2.1 測(cè)繪塑件圖紙,完成其CAD三維造型設(shè)計(jì)2.2 模具方案設(shè)計(jì): (1) 注塑機(jī)類(lèi)型的選擇由于機(jī)構(gòu)的結(jié)構(gòu)和產(chǎn)量以及所給的各項(xiàng)要求,進(jìn)行綜合的考慮,采用螺旋臥式注塑機(jī);(2) 注塑模類(lèi)型的選擇由于有側(cè)凹,現(xiàn)擬采用斜導(dǎo)柱操作的哈夫式注射模;(3) 澆注系統(tǒng)的選擇因要求一模兩腔,所以將型腔對(duì)稱(chēng)放置,使用圓錐型主流道和球形頭拉料桿的冷料穴。將分流道對(duì)稱(chēng)設(shè)置,分流道截面采用梯形截面,澆口采用潛伏式澆口,利用分型面或配合間隙排氣;(4) 分型面的選擇 骨輪形狀簡(jiǎn)單,可選擇骨輪上下兩個(gè)端面作為分型面;(5) 側(cè)抽芯機(jī)構(gòu)的選擇 由于骨輪有側(cè)凹,需要側(cè)抽芯機(jī)構(gòu),使用斜導(dǎo)柱抽芯機(jī)構(gòu),將滑塊對(duì)稱(chēng)向外滑行,斜導(dǎo)柱固定在定模一側(cè),滑塊在動(dòng)模一側(cè),并采用T型導(dǎo)軌。2.3 成型零件尺寸的計(jì)算2.4 完成骨輪注射模的裝配圖設(shè)計(jì)和全部零件的圖紙?jiān)O(shè)計(jì)2.5 利用ProE三維軟件對(duì)該注射模進(jìn)行三維造型設(shè)計(jì)2.6 完成該注射模的制造工藝設(shè)計(jì)2.7 完成設(shè)計(jì)說(shuō)明書(shū)的撰寫(xiě) 畢 業(yè) 設(shè) 計(jì)(論 文)開(kāi) 題 報(bào) 告指導(dǎo)教師意見(jiàn):1對(duì)“文獻(xiàn)綜述”的評(píng)語(yǔ):2對(duì)本課題的深度、廣度及工作量的意見(jiàn)和對(duì)設(shè)計(jì)(論文)結(jié)果的預(yù)測(cè): 指導(dǎo)教師: 年 月 日所在專(zhuān)業(yè)審查意見(jiàn): 負(fù)責(zé)人: 年 月 日 編號(hào): 畢業(yè)設(shè)計(jì)(論文)外文翻譯(原文)院 (系): 國(guó)防生學(xué)院 專(zhuān) 業(yè):機(jī)械設(shè)計(jì)制造及其自動(dòng)化 學(xué)生姓名: 蔡秀濱 學(xué) 號(hào): 1001020105 指導(dǎo)教師單位: 機(jī)電工程學(xué)院 姓 名: 郭中玲 職 稱(chēng): 高級(jí)工程師 2014年 3 月 9 日Contents1.The Injection Molding12.Automated surface nishing of plastic injection mold steel with spherical grinding and ball burnishing processes14第 22 頁(yè) 共 23 頁(yè) 桂林電子科技大學(xué)畢業(yè)(論文)報(bào)告專(zhuān)用紙 The Injection Molding Alp Tekin Ergenc , Deniz Ozde KocaYildiz Tecnical University, Mechanical Engineering Department, IC Engines Laboratory, TurkeyThe Introduction of MoldsThe mold is at the core of a plastic manufacturing process because its cavity gives a part its shape. This makes the mold at least as critical-and many cases more so-for the quality of the end product as, for example, the plasticiting unit or other components of the processing equipment.Mold MaterialDepending on the processing parameters for the various processing methods as well as the length of the production run, the number of finished products to be produced, molds for plastics processing must satisfy a great variety of requirements. It is therefore not surprising that molds can be made from a very broad spectrum of materials, including-from a technical standpoint-such exotic materials as paper matched and plaster. However, because most processes require high pressures, often combined with high temperatures, metals still represent by far the most important material group, with steel being the predominant metal. It is interesting in this regard that, in many cases, the selection of the mold material is not only a question of material properties and an optimum price-to-performance ratio but also that the methods used to produce the mold, and thus the entire design, can be influenced.A typical example can be seen in the choice between cast metal molds, with their very different cooling systems, compared to machined molds. In addition, the production technique can also have an effect; for instance, it is often reported that, for the sake of simplicity, a prototype mold is frequently machined from solid stock with the aid of the latest technology such as computer-aided (CAD) and computer-integrated manufacturing (CIMS). In contrast to the previously used methods based on the use of patterns, the use of CAD and CAM often represents the more economical solution today, not only because this production capability is available pin-house but also because with any other technique an order would have to be placed with an outside supplier.Overall, although high-grade materials are often used, as a rule standard materials are used in mold making. New, state-of-the art (high-performance) materials, such as ceramics, for instance, are almost completely absent. This may be related to the fact that their desirable characteristics, such as constant properties up to very high temperatures, are not required on molds, whereas their negative characteristics, e. g. low tensile strength and poor thermal conductivity, have a clearly related to ceramics, such as sintered material, is found in mild making only to a limited degree. This refers less to the modern materials and components produced by powder metallurgy, and possibly by hot isocratic pressing, than to sintered metals in the sense of porous, air-permeable materials.Removal of air from the cavity of a mold is necessary with many different processing methods, and it has been proposed many times that this can be accomplished using porous metallic materials. The advantages over specially fabricated venting devices, particularly in areas where melt flow fronts meet, I, e, at weld lines, are as obvious as the potential problem areas: on one hand, preventing the texture of such surfaces from becoming visible on the finished product, and on the other hand, preventing the microspores from quickly becoming clogged with residues (broken off flash, deposits from the molding material, so-called plate out, etc.). It is also interesting in this case that completely new possibilities with regard to mold design and processing technique result from the use of such materials. A. Design rules There are many rules for designing molds. These rules and standard practices are based on logic, past experience, convenience, and economy. For designing, mold making, and molding, it is usually of advantage to follow the rules. But occasionally, it may work out better if a rule is ignored and an alternative way is selected. In this text, the most common rules are noted, but the designer will learn only from experience which way to go. The designer must ever be open to new ideas and methods, to new molding and mold materials that may affect these rules.B. The basic mold1. Mold cavity space The mold cavity space is a shape inside the mold, “excavated” in such a manner that when the molding material is forced into this space it will take on the shape of the cavity space and, therefore, the desired product. The principle of a mold is almost as old as human civilization. Molds have metals into sand forms. Such molds, which are still used today in foundries, can be used only once because the mold is destroyed to release the product after it has solidified. Today, we are looking for permanent molds that can be used over and over. Now molds are made from strong, durable materials, such as steel, or from softer aluminum or metal alloys and even from certain plastics where a long mold life is not required because the planned production is small. In injection molding the plastic is injected into the cavity space with high pressure, so the mold must be strong enough to resist the injection pressure without deforming.2. Number of cavities Many molds, particularly molds for larger products, are built for only cavity space, but many molds, especially large production molds, are built with 2 or more cavities. The reason for this is purely economical. It takes only little more time to inject several cavities than to inject one. For example, a 4-cavity mold requires only one-fourth of the machine time of a single-cavity mold. Conversely, the production increases in proportion to the number of cavities. A mold with more cavities is more expensive to build than a single-cavity mold, but not necessarily 4 times as much as a single-cavity mold. But it may also require a larger machine with larger platen area and more clamping capacity, and because it will use 4 times the amount of plastic, it may need a large injection unit, so the machine hour cost will be higher than for a machine large enough for the smaller mold.3. Cavity shape and shrinkage The shape of the cavity is essentially the “negative” of the shape of the desired product, with dimensional allowance added to allow for shrinking of the plastic. The shape of the cavity is usually created with chip-removing machine tools, or with electric discharge machining, with chemical etching, or by any new method that may be available to remove metal or build it up, such as galvanic processes. It may also be created by casting certain metals in plaster molds created from models of the product to be made, or by casting some suitable hard plastics. The cavity shape can be either cut directly into the mold plates or formed by putting inserts into the plates.C. Cavity and core By convention, the hollow portion of the cavity space is called the cavity. The matching, often raised portion of the cavity space is called the core. Most plastic products are cup-shaped. This does not mean that they look like a cup, but they do have an inside and an outside. The outside of the product is formed by the cavity, the inside by the core. The alternative to the cup shape is the flat shape. In this case, there is no specific convex portion, and sometimes, the core looks like a mirror image of the cavity. Typical examples for this are plastic knives, game chips, or round disks such as records. While these items are simple in appearance, they often present serious molding problems for ejection of the product. The reason for this is that all injection molding machines provide an ejection mechanism on the moving platen and the products tend to shrink onto and cling to the core, from where they are then ejected. Most injection molding machines do not provide ejection mechanisms on the injection side.Polymer Processing Polymer processing, in its most general context, involves the transformation of a solid (sometimes liquid) polymeric resin, which is in a random form (e.g., powder, pellets, beads), to a solid plastics product of specified shape, dimensions, and properties. This is achieved by means of a transformation process: extrusion, molding, calendaring, coating, thermoforming, etc. The process, in order to achieve the above objective, usually involves the following operations: solid transport, compression, heating, melting, mixing, shaping, cooling, solidification, and finishing. Obviously, these operations do not necessarily occur in sequence, and many of them take place simultaneously. Shaping is required in order to impart to the material the desired geometry and dimensions. It involves combinations of viscoelastic deformations and heat transfer, which are generally associated with solidification of the product from the melt. Shaping includes: two-dimensional operations, e.g. die forming, calendaring and coating; three-dimensional molding and forming operations. Two-dimensional processes are either of the continuous, steady state type (e.g. film and sheet extrusion, wire coating, paper and sheet coating, calendaring, fiber spinning, pipe and profile extrusion, etc.) or intermittent as in the case of extrusions associated with intermittent extrusion blow molding. Generally, molding operations are intermittent, and, thus, they tend to involve unsteady state conditions. Thermoforming, vacuum forming, and similar processes may be considered as secondary shaping operations, since they usually involve the reshaping of an already shaped form. In some cases, like blow molding, the process involves primary shaping (pair-son formation) and secondary shaping (pair son inflation). Shaping operations involve simultaneous or staggered fluid flow and heat transfer. In two-dimensional processes, solidification usually follows the shaping process, whereas solidification and shaping tend to take place simultaneously inside the mold in three dimensional processes. Flow regimes, depending on the nature of the material, the equipment, and the processing conditions, usually involve combinations of shear, extensional, and squeezing flows in conjunction with enclosed (contained) or free surface flows. The thermo-mechanical history experienced by the polymer during flow and solidification results in the development of microstructure (morphology, crystallinity, and orientation distributions) in the manufactured article. The ultimate properties of the article are closely related to the microstructure. Therefore, the control of the process and product quality must be based on an understanding of the interactions between resin properties, equipment design, operating conditions, thermo-mechanical history, microstructure, and ultimate product properties. Mathematical modeling and computer simulation have been employed to obtain an understanding of these interactions. Such an approach has gained more importance in view of the expanding utilization of computer design/computer assisted manufacturing/computer aided engineering (CAD/CAM/CAE) systems in conjunction with plastics processing. It will emphasize recent developments relating to the analysis and simulation of some important commercial process, with due consideration to elucidation of both thermo-mechanical history and microstructure development. As mentioned above, shaping operations involve combinations of fluid flow and heat transfer, with phase change, of a visco-elastic polymer melt. Both steady and unsteady state processes are encountered. A scientific analysis of operations of this type requires solving the relevant equations of continuity, motion, and energy (I. e. conservation equations).Injection Molding Many different processes are used to transform plastic granules, powders, and liquids into final product. The plastic material is in moldable form, and is adaptable to various forming methods. In most cases thermoplastic materials are suitable for certain processes while thermosetting materials require other methods of forming. This is recognized by the fact that thermoplastics are usually heated to a soft state and then reshaped before cooling. Theromosets, on the other hand have not yet been polymerized before processing, and the chemical reaction takes place during the process, usually through heat, a catalyst, or pressure. It is important to remember this concept while studying the plastics manufacturing processes and the polymers used. Injection molding is by far the most widely used process of forming thermoplastic materials. It is also one of the oldest. Currently injection molding accounts for 30% of all plastics resin consumption. Since raw material can be converted by a single procedure, injection molding is suitable for mass production of plastics articles and automated one-step production of complex geometries. In most cases, finishing is not necessary. Typical products include toys, automotive parts, household articles, and consumer electronics goods, Since injection molding has a number of interdependent variables, it is a process of considerable complexity. The success of the injection molding operation is dependent not only in the proper setup of the machine variables, but also on eliminating shot-to-shot variations that are caused by the machine hydraulics, barrel temperature variations, and changes in material viscosity. Increasing shot-to-shot repeatability of machine variables helps produce parts with tighter tolerance, lowers the level of rejects, and increases product quality ( i.e., appearance and serviceability). The principal objective of any molding operation is the manufacture of products: to a specific quality level, in the shortest time, and using a repeatable and fully automatic cycle. Molders strive to reduce or eliminate rejected parts, or parts with a high added value such as appliance cases, the payoff of reduced rejects is high. A typical injection molding cycle or sequence consists of five phases:1 Injection or mold filling2 Packing or compression3 Holding4 Cooling5 Part ejectionInjection Molding OverviewProcessInjection molding is a cyclic process of forming plastic into a desired shape by forcingthe material under pressure into a cavity. The shaping is achieved by cooling(thermoplastics) or by a chemical reaction (thermosets). It is one of the most commonand versatile operations for mass production of complex plastics parts with excellentdimensional tolerance. It requires minimal or no finishing or assembly operations. Inaddition to thermoplastics and thermosets, the process is being extended to suchmaterials as fibers, ceramics, and powdered metals, with polymers as binders.ApplicationsApproximately 32 percent by weight of all plastics processed go through injection moldingmachines. Historically, the major milestones of injection molding include the invention of thereciprocating screw machine and various new alternative processes, and the application of computersimulation to the design and manufacture of plastics parts.Development of the injection molding machineSince its introduction in the early 1870s, the injection molding machine has undergone significantmodifications and improvements. In particular, the invention of the reciprocating screw machine hasrevolutionized the versatility and productivity of the thermoplastic injection molding process.Benefits of the reciprocating screwApart from obvious improvements in machine control and machine functions, the majordevelopment for the injection molding machine is the change from a plunger mechanism to areciprocating screw. Although the plunger-type machine is inherently simple, its popularity waslimited due to the slow heating rate through pure conduction only. The reciprocating screw canplasticize the material more quickly and uniformly with its rotating motion, as shown in Figure 1. Inaddition, it is able to inject the molten polymer in a forward direction, as a plunger.Development of the injection molding processThe injection molding process was first used only with thermoplastic polymers. Advances in theunderstanding of materials, improvements in molding equipment, and the needs of specific industrysegments have expanded the use of the process to areas beyond its original scope.Alternative injection molding processesDuring the past two decades, numerous attempts have been made to develop injection moldingprocesses to produce parts with special design features and properties. Alternative processes derivedfrom conventional injection molding have created a new era for additional applications, more designfreedom, and special structural features. These efforts have resulted in a number of processes,including: Co-injection (sandwich) molding Fusible core injection molding) Gas-assisted injection molding Injection-compression molding Lamellar (microlayer) injection moldin Live-feed injection molding Low-pressure injection molding Push-pull injection molding Reactive molding Structural foam injection molding Thin-wall moldingComputer simulation of injection molding processesBecause of these extensions and their promising future, computer simulation of the process has alsoexpanded beyond the early lay-flat, empirical cavity-filling estimates. Now, complex programs simulate post-filling behavior, reaction kinetics, and the use of two materials with different properties, or two distinct phases, during the process.The Simulation section provides information on using C-MOLD products.Among the Design topicsare several examples that illustrate how you can use CAE tools to improve your part and molddesign and optimize processing conditions.Co-injection (sandwich) moldingOverviewCo-injection molding involves sequential or concurrent injection of two different butcompatible polymer melts into a cavity. The materials laminate and solidify. This processproduces parts that have a laminated structure, with the core material embedded betweenthe layers of the skin material. This innovative process offers the inherent flexibility ofusing the optimal properties of each material or modifying the properties of the moldedpart.FIGURE 1. Four stages of co-injection molding. (a) Short shot of skin polymer melt (shown in dark green)is injected into the mold. (b) Injection of core polymer melt until cavity is nearly filled, as shown in (c). (d)Skin polymer is injected again, to purge the core polymer away from the sprue.Fusible core injection moldingOverviewThe fusible (lost, soluble) core injection molding process illustrated below producessingle-piece, hollow parts with complex internal geometry. This process molds a coreinside the plastic part. After the molding, the core will be physically melted or chemicallydissolved, leaving its outer geometry as the internal shape of the plastic part.FIGURE 1. Fusible (lost, soluble) core injection moldingGas-assisted injection moldingGas-assisted processThe gas-assisted injection molding process begins with a partial or full injection ofpolymer melt into the mold cavity. Compre
收藏