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畢 業(yè) 設(shè) 計(jì)(論 文)開題報(bào)告
設(shè)計(jì)(論文)題目: 冰露礦泉水瓶瓶蓋螺紋伺服脫模模具設(shè)計(jì)
學(xué)生姓名:
學(xué) 院:
專 業(yè):
班 級(jí):
學(xué) 號(hào):
指導(dǎo)教師:
年2月26日
開題報(bào)告填寫要求
1.開題報(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、所在專業(yè)和學(xué)院審查后生效。
2.開題報(bào)告內(nèi)容必須按教務(wù)處統(tǒng)一設(shè)計(jì)的電子文檔標(biāo)準(zhǔn)格式打印,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。
3.“文獻(xiàn)綜述”應(yīng)按論文的框架成文,并直接填寫在本開題報(bào)告第一欄目?jī)?nèi),學(xué)生寫文獻(xiàn)綜述的參考文獻(xiàn)應(yīng)不少于10篇(不包括辭典、手冊(cè))。
4.有關(guān)年月日等日期的填寫,應(yīng)當(dāng)按照國(guó)標(biāo)GB/T 7408—94《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)字書寫。如“2015年6月26日”或“2015-06-26”。
5.開題報(bào)告(文獻(xiàn)綜述)字體請(qǐng)按宋體、小四號(hào)書寫,行間距1.5倍。
畢 業(yè) 設(shè) 計(jì)(論 文)開 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,每人撰寫不少于1000字的文獻(xiàn)綜述:
1.注塑模具簡(jiǎn)介
模具是工業(yè)生產(chǎn)中使用極為廣泛的基礎(chǔ)工藝裝備。在汽車、電機(jī)、儀表、電器、電子、通信、家電和輕工業(yè)等行業(yè)中,60%~80%的零件都依靠模具成形[1],并且隨著近年來(lái)這些行業(yè)的迅速發(fā)展,對(duì)模具的要求越來(lái)越高,結(jié)構(gòu)也越來(lái)越復(fù)雜。用模具生產(chǎn)制件所表現(xiàn)出來(lái)的高精度、高復(fù)雜性、高一致性、高生產(chǎn)效率和低耗率,是其它加工制造方法所不能比擬的[2]。隨著塑料工業(yè)的飛速發(fā)展和通用塑料與工程塑料在強(qiáng)度和精度等方面的不斷提高,塑料制品的應(yīng)用范圍也在不斷地?cái)U(kuò)大,越來(lái)越普遍地采用塑料成型。該方法適用于全部熱塑性塑料和部分熱固性塑料,制得的塑料制品數(shù)量之大是其它成型方法望塵莫及的[3]。作為注塑成型加工的主要工具之一注塑模具,在質(zhì)量、精度、制造周期以及注塑成型過(guò)程中的生產(chǎn)效率等方面水平高低,直接影響產(chǎn)品的質(zhì)量、產(chǎn)量、成本及產(chǎn)品的更新?lián)Q代,同時(shí)也決定著企業(yè)在市場(chǎng)競(jìng)爭(zhēng)中的反映能力和速度[4]。
由于注塑模具的使用特點(diǎn),決定了模具設(shè)計(jì)也區(qū)別與其他行業(yè)。注塑模具設(shè)計(jì)要考慮的要點(diǎn)如下[5]:
1.塑件的物理力學(xué)性能,如強(qiáng)度、剛度、韌性、彈性、吸水性以及對(duì)應(yīng)力的敏感性,不同塑料品種其性能各有所長(zhǎng),在設(shè)計(jì)塑件時(shí)應(yīng)充分發(fā)揮其性能上的優(yōu)點(diǎn),避免或補(bǔ)償其缺點(diǎn)。
2.塑料的成型工藝性,如流動(dòng)性、成型收縮率的各向差異等。塑件形狀應(yīng)有利于成型時(shí)充模、排氣、補(bǔ)縮,同時(shí)能使熱塑性塑料制品達(dá)到高效、均勻冷卻或使熱固性塑料制品均勻地固化。
3.塑件結(jié)構(gòu)能使模具總體結(jié)構(gòu)盡可能簡(jiǎn)化,特別是避免側(cè)向分型抽芯機(jī)構(gòu)和簡(jiǎn)化脫模結(jié)構(gòu)。使模具零件符合制造工藝的要求。
對(duì)于特殊用途的制品,還要考慮其光學(xué)性能、熱學(xué)性能、電性能、耐腐蝕性能等。
2.當(dāng)前國(guó)內(nèi)塑料模具發(fā)展概況及趨勢(shì)
目前,我國(guó)的模具制造技術(shù)已從過(guò)去只能制造簡(jiǎn)單模具發(fā)展到可以制造大型、精密、復(fù)雜、長(zhǎng)壽命的模具。在塑料模具方面[6],能設(shè)計(jì)制造汽車保險(xiǎn)杠及整體儀表盤大型注射模。一些塑料模主要生產(chǎn)企業(yè)利用計(jì)算機(jī)輔助分析(CAE)技術(shù)對(duì)塑料注塑過(guò)程進(jìn)行流動(dòng)分析、冷卻分析、應(yīng)力分析等,合理選擇澆口位置、尺寸、注塑工藝參數(shù)及冷卻系統(tǒng)的布置等,使模具設(shè)計(jì)方案進(jìn)一步優(yōu)化,也縮短了模具設(shè)計(jì)和制造周期采用模具先進(jìn)加工技術(shù)及設(shè)備,使模具制造能力大為提高。采用CAE技術(shù)[7],可以完全代替試模,CAE技術(shù)提供了從制品設(shè)計(jì)到生產(chǎn)的完整解決方案,在模具制造加工之前,在計(jì)算機(jī)上對(duì)整個(gè)注射成型過(guò)程進(jìn)行模擬分析[8],準(zhǔn)確預(yù)測(cè)熔體的填充、保壓、冷卻情況,以及制品中的應(yīng)力分布、分子和纖維取向分布、制品的收縮和翹曲變形等情況,以便設(shè)計(jì)者能盡早發(fā)現(xiàn)問題,及時(shí)修改制件和模具設(shè)計(jì),而不是等到試模以后再返修模具。這不僅是對(duì)傳統(tǒng)模具設(shè)計(jì)方法的一次突破[9],而且對(duì)減少甚至避免模具返修報(bào)廢、提高制品質(zhì)量和降低成本等,都有著重大的技術(shù)經(jīng)濟(jì)意義。某些國(guó)外電加工機(jī)床具有內(nèi)容豐富、實(shí)用可靠的工藝數(shù)據(jù)和專家系統(tǒng),使模具的深槽窄縫加工、微細(xì)加工、鏡面加工等效率和質(zhì)量大大提高。新的模糊控制系統(tǒng)具有加工反力的監(jiān)測(cè)和控制,提高了大面積加工的深度控制精度。電火花混粉加工技術(shù)的應(yīng)用有效地提高了模具表面質(zhì)量。模具逆向工程技術(shù)、快速經(jīng)濟(jì)模具制造技術(shù)、三維掃描測(cè)量技術(shù)及數(shù)控模具雕刻機(jī)的發(fā)展與應(yīng)用,對(duì)模具制造能力的提高也起到了很大作用[10]。我國(guó)經(jīng)濟(jì)仍處于高速發(fā)展階段,國(guó)際上經(jīng)濟(jì)全球化發(fā)展趨勢(shì)日趨明顯,這為我國(guó)模具工業(yè)高速發(fā)展提供了良好的條件和機(jī)遇。一方面,國(guó)內(nèi)模具市場(chǎng)將繼續(xù)高速發(fā)展;另一方面,模具制造也逐漸向我國(guó)轉(zhuǎn)移以及跨國(guó)集團(tuán)到我國(guó)進(jìn)行模具采購(gòu)趨向也十分明顯。
隨著計(jì)算機(jī)技術(shù)的發(fā)展應(yīng)用,模具設(shè)計(jì)與制造技術(shù)正朝著數(shù)字化方向發(fā)展。特別是模具成型零件方面的軟件等[11],這些技術(shù)采用計(jì)算機(jī)輔助設(shè)計(jì),進(jìn)而將數(shù)據(jù)交換到加工制造設(shè)備,實(shí)現(xiàn)計(jì)算機(jī)輔助制造,或?qū)⒃O(shè)計(jì)與制造連成一體實(shí)現(xiàn)設(shè)計(jì)制造一體化。
3.參考文獻(xiàn)
[1]齊衛(wèi)東主編.塑料模具設(shè)計(jì)與制造.北京:高等教育出版社,2004
[2]鄧明主編.實(shí)用模具設(shè)計(jì)簡(jiǎn)明手冊(cè)[M].第1版.北京:機(jī)械工業(yè)出版社,2010.1
[3]馮剛.我國(guó)注塑模具關(guān)鍵技術(shù)的研究與應(yīng)用進(jìn)展[J].塑料工業(yè)雜志社,2014.
[4]屈華昌,吳夢(mèng)陵.塑料成型工藝與模具設(shè)計(jì)[M].北京:高等教育出版社,2014.
[5]付拴林,梁彥飛.注塑模具技術(shù)分析與發(fā)展展望[J].內(nèi)燃機(jī)與配件,2018(01):108-109.
[6]張冠杰.注塑模具CAD/CAE/CAM技術(shù)研究[D].天津大學(xué),2016.
[7]Changrong Chen,Yan Wang,Hengan Ou,et al.A review on remanufacture of dies and moulds[J].Journal of Cleaner Production,2014,64:14~23.
[8]禾子.制約我國(guó)模具行業(yè)快速發(fā)展的四大因素分析及未來(lái)展望[J].福建輕紡, 2014,18(01):26~28.
[9] 陳隆波,李國(guó)輝.淺析CAD/CAE/CAM常用軟件在注塑模具設(shè)計(jì)中的應(yīng)用[J].黑龍科技信息,2017,(4):161.
[10]彭志榮.注塑模具的標(biāo)準(zhǔn)化及自動(dòng)化設(shè)計(jì)[J].硅谷,2013,6(08):119-120
[11]韓永強(qiáng),吳曉春.國(guó)內(nèi)外塑料模具鋼研究現(xiàn)狀與發(fā)展趨勢(shì)[J].模具工業(yè),2018,44(09):1~7.
畢 業(yè) 設(shè) 計(jì)(論 文)開 題 報(bào) 告
2.本課題要研究的內(nèi)容、解決的問題和擬采用的研究手段(途徑)等:
一、設(shè)計(jì)任務(wù)
1、完成礦泉水瓶蓋螺紋伺服脫模模具設(shè)計(jì)設(shè)計(jì)說(shuō)明書;
2、完成礦泉水瓶蓋螺紋伺服脫模模具裝配圖和零件圖;
3、進(jìn)行凹模零件圖進(jìn)行機(jī)械加工工藝的編制;
二、設(shè)計(jì)思路
三、課題的重點(diǎn)難點(diǎn)
(1) 利用 UG 完成礦泉水瓶蓋模具結(jié)構(gòu)的 3D設(shè)計(jì);
(2) 側(cè)抽芯機(jī)構(gòu)的設(shè)計(jì),側(cè)抽芯結(jié)構(gòu)設(shè)計(jì)時(shí),為了使外側(cè)形狀滿足設(shè)計(jì)要求且結(jié)構(gòu)簡(jiǎn)單,如何設(shè)計(jì)方便脫模是關(guān)鍵
(3) 塑件內(nèi)側(cè)有螺紋,在注射完成后如何脫模是本次課題的關(guān)鍵,能否強(qiáng)制脫模是需要考慮的問題;
(4)本次塑件應(yīng)是大批量生產(chǎn),如何排樣及設(shè)計(jì)澆注系統(tǒng)也是需要考慮的問題。
四、方案設(shè)計(jì)
1、根據(jù)零件畫出零件圖
2、成型零件的工藝分析
3、分型面及型腔數(shù)量的確定
4、澆注系統(tǒng)設(shè)計(jì)
5、成型零件設(shè)計(jì)
6、側(cè)抽芯機(jī)構(gòu)設(shè)計(jì);
7、導(dǎo)向零件的設(shè)計(jì)
8、排氣系統(tǒng)設(shè)計(jì)
9、模架的確定
五、任務(wù)進(jìn)程
2019年12月18日-2019年12月20日指導(dǎo)教師下發(fā)任務(wù)書,師生見面討論、并當(dāng)面給學(xué)生分配設(shè)計(jì)任務(wù)
2019年12月23日-2020年3月2日 學(xué)生搜集資料,提交開題報(bào)告及外文翻譯的初稿
2020年3月9日-2020年3月17日 提交開題報(bào)告、外文參考資料及譯文的定稿
2020年3月18日-2020年3月30日 進(jìn)一步完善前期的各項(xiàng)材料,提交各項(xiàng)材料的定稿,開始準(zhǔn)備畢業(yè)設(shè)計(jì)的課題研究
2020年4月1日- 2020年4月8日 進(jìn)行畢業(yè)設(shè)計(jì)中期檢查,學(xué)生進(jìn)行課題的設(shè)計(jì)、編程、安裝、調(diào)試
2020年4月9日- 2020年5月18日 學(xué)生進(jìn)一步完善課題的設(shè)計(jì)、編程、安裝、調(diào)試,教師評(píng)閱學(xué)生畢業(yè)設(shè)計(jì);學(xué)生準(zhǔn)備畢業(yè)設(shè)計(jì)答辯
畢 業(yè) 設(shè) 計(jì)(論 文)開 題 報(bào) 告
指導(dǎo)教師意見:
1.對(duì)“文獻(xiàn)綜述”的評(píng)語(yǔ):
對(duì)文獻(xiàn)了解較深刻,能完成畢業(yè)設(shè)計(jì)相關(guān)閱讀。
2.對(duì)本課題研究的思路、方法、對(duì)策、措施的預(yù)期成效等的評(píng)價(jià):
研究方法思路清晰,方法得當(dāng)。同意開題
3.是否同意開題:?同意 ?不同意
指導(dǎo)教師:
2020年2月27日
所在專業(yè)審查意見:
同意指導(dǎo)老師審核,同意開題,望嚴(yán)格按時(shí)按進(jìn)程完成設(shè)計(jì)任務(wù)。
專業(yè)(系)負(fù)責(zé)人:
2020年2月29日
畢業(yè)設(shè)計(jì)(論文)評(píng)閱教師評(píng)閱表
題 目
冰露礦泉水瓶瓶蓋螺紋伺服脫模模具設(shè)計(jì)
學(xué) 生 姓 名
學(xué) 號(hào)
指 導(dǎo) 教 師
職 稱
高級(jí)工程師
學(xué) 歷
本科
評(píng)分指標(biāo)(參考)
得分
1.理工類:設(shè)計(jì)(論文)方案合理性,理論分析充分性(5分)
文經(jīng)管類:論文指導(dǎo)思想(5分)。
3.7
2.理工類:設(shè)計(jì)(論文)性能指標(biāo),實(shí)驗(yàn)數(shù)據(jù)準(zhǔn)確性,圖表、圖紙等數(shù)量與質(zhì)量(5分)
文經(jīng)管類:論文論據(jù)的充分性與正確性(5分)
3.6
3.設(shè)計(jì)(論文)創(chuàng)新性,成果的學(xué)術(shù)或應(yīng)用價(jià)值(5分)
3.5
4.設(shè)計(jì)(論文)的結(jié)構(gòu)、文字表達(dá)及書寫情況(5分)
4.0
評(píng)閱教師評(píng)分(滿分20分):
14.8
評(píng)閱教師評(píng)語(yǔ):
論文分析冰露礦泉水瓶瓶蓋螺紋伺服脫模模具注塑成型工藝,制訂了注塑成型方案,完成了注塑成型模具的設(shè)計(jì),制訂的工藝方案基本正確,模具結(jié)構(gòu)基本合理,引用公式計(jì)算鎖模力基本正確,基本能綜合運(yùn)用所學(xué)知識(shí)解決畢業(yè)設(shè)計(jì)給出的問題,任務(wù)量滿足畢設(shè)要求。
是否同意答辯:
評(píng)閱教師:
年5月13日
畢業(yè)設(shè)計(jì)(論文)選題、審題表
學(xué) 院
機(jī)械與電氣工程學(xué)院
出題教師
姓 名
專 業(yè)
材料成型及控制工程
職 稱
申報(bào)課題名稱
冰露礦泉水瓶瓶蓋螺紋伺服脫模模具設(shè)計(jì)
課題類型
£畢業(yè)設(shè)計(jì)(論文) R畢業(yè)設(shè)計(jì) £畢業(yè)論文
課題性質(zhì)
?A.理論研究類(理工) ?B.實(shí)驗(yàn)研究類(理工) ?C.工程設(shè)計(jì)類(理工) ?D.軟件開發(fā)類(理工) ?E.專題類(文、經(jīng)、管) ?F.論辯類(文、經(jīng)、管) ?G.綜述類(文、經(jīng)、管) ?H.綜合論文類(文、經(jīng)、管) ?I.藝術(shù)研究類(藝術(shù)) ?J.藝術(shù)設(shè)計(jì)類(藝術(shù)) ?K.綜合藝術(shù)類(藝術(shù)) ?L.其他
課題來(lái)源
RA.結(jié)合社會(huì)生產(chǎn)實(shí)際 £B.教師課題 £C.自擬課題 £D.其他
課題簡(jiǎn)介
主要指研究設(shè)計(jì)該課題的背景介紹及目的、意義。
塑料模具設(shè)計(jì)是目前市場(chǎng)上重要的塑料產(chǎn)品成形工藝,對(duì)于螺紋脫模方式也比較多,如何能夠更快更準(zhǔn)確的 進(jìn)行脫模是目前塑料模具重要方向,螺紋伺服脫模就是其中重要的一種方法。重點(diǎn)是了解伺服模塊的設(shè)計(jì)與選擇。
課題要求(包括應(yīng)具備的條件)
主要指本課題技術(shù)方面的要求,而“條件”指從事該課題必須應(yīng)具備的基本條件(如儀器設(shè)備、場(chǎng)地、文獻(xiàn)資料等)。
要求在了解塑料模具設(shè)計(jì)與制造工藝的基礎(chǔ)上,抓緊時(shí)間學(xué)習(xí)注塑成型原理,并了解注塑模具精度的保證問題。并且了解塑料瓶蓋使用要求,對(duì)塑料模具工作尺寸的計(jì)算一定要仔細(xì)全面,對(duì)注塑機(jī)的選擇合適并且對(duì)鎖模力等進(jìn)行校核。模具成型零件工藝編制說(shuō)明書上要表述詳盡。能完成隨身塑料瓶蓋塑料模具設(shè)計(jì)及制造;
工作量要求:
1、完成設(shè)計(jì)說(shuō)明書一份;
2、完成塑料瓶蓋塑料模具設(shè)計(jì)及制造裝配圖和零件圖若干;
3、完成成型零件的工藝編制。
4、根據(jù)凹模零件圖進(jìn)行機(jī)械加工工藝的編制,對(duì)其進(jìn)行基于UGNX8.0的自動(dòng)編程和加工,并生產(chǎn)后置程序;
5、總圖量:累加起來(lái)達(dá)到A0 2張;
課題預(yù)計(jì)
工作量大小
?大 ?適中 ?小
課題預(yù)計(jì)難易程度
?難 ?一般 ?易
所在專業(yè)審查意見:
同意
專業(yè)(系)負(fù)責(zé)人:
2019年12月11日
學(xué)院審查意見:
同意
學(xué)院負(fù)責(zé)人:
2019年12月12日
畢 業(yè) 設(shè) 計(jì)(論 文)任務(wù)書
設(shè)計(jì)(論文)題目: 冰露礦泉水瓶瓶蓋螺紋伺服脫模模具設(shè)計(jì)
學(xué)生姓名:
學(xué) 院: 機(jī)械與電氣工程學(xué)院
專 業(yè): 材料成型及控制工程
班 級(jí):
學(xué) 號(hào):
指導(dǎo)教師:
下發(fā)任務(wù)書日期: 年12月20日
任務(wù)書填寫要求
1.畢業(yè)設(shè)計(jì)(論文)任務(wù)書由指導(dǎo)教師根據(jù)各課題的具體情況填寫,經(jīng)學(xué)生所在專業(yè)的負(fù)責(zé)人審查、學(xué)院領(lǐng)導(dǎo)簽字后生效。此任務(wù)書應(yīng)在畢業(yè)設(shè)計(jì)(論文)開始前至少一周內(nèi)填好并發(fā)給學(xué)生。
2.任務(wù)書內(nèi)容必須按教務(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,要求正文小4號(hào)宋體,1.5倍行距,禁止打印在其它紙上剪貼。
3.任務(wù)書內(nèi)填寫的內(nèi)容,必須和學(xué)生畢業(yè)設(shè)計(jì)(論文)完成的情況相一致,若有變更,應(yīng)當(dāng)經(jīng)過(guò)所在專業(yè)及學(xué)院主管領(lǐng)導(dǎo)審批后方可重新填寫。
4.任務(wù)書內(nèi)有關(guān)“學(xué)院”、“專業(yè)”等名稱的填寫,應(yīng)寫中文全稱,不能寫數(shù)字代碼。學(xué)生的“學(xué)號(hào)”要寫全號(hào),不能只寫最后2位或1位數(shù)字。
5.任務(wù)書內(nèi)“主要參考文獻(xiàn)”的填寫,應(yīng)按照《三江學(xué)院畢業(yè)設(shè)計(jì)(論文)撰寫規(guī)范》的要求書寫。
6.有關(guān)年月日等日期的填寫,應(yīng)當(dāng)按照國(guó)標(biāo)GB/T 7408—94《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)字書寫。如“2015年6月26日”或“2015-06-26”。
畢 業(yè) 設(shè) 計(jì)(論 文)任 務(wù) 書
1.本畢業(yè)設(shè)計(jì)(論文)課題應(yīng)達(dá)到的目的:
通過(guò)本次畢業(yè)設(shè)計(jì),掌握注塑模具設(shè)計(jì)的基本方法,能夠完成簡(jiǎn)單模具設(shè)計(jì)。學(xué)會(huì)設(shè)計(jì)過(guò)程遇到問題查閱手冊(cè)的方法,并能夠運(yùn)用好計(jì)算機(jī)繪圖基本能力。初步接觸CAE技術(shù),會(huì)基本模具CAM加工。
2.本畢業(yè)設(shè)計(jì)(論文)課題任務(wù)的內(nèi)容和要求(包括原始數(shù)據(jù)、技術(shù)要求、工作要求等):
要求在了解塑料模具設(shè)計(jì)與制造工藝的基礎(chǔ)上,抓緊時(shí)間學(xué)習(xí)注塑成型原理,并了解注塑模具精度的保證問題。并且了解冰露礦泉水瓶瓶蓋螺紋伺服脫模模具設(shè)計(jì)使用要求,對(duì)塑料模具工作尺寸的計(jì)算一定要仔細(xì)全面,對(duì)注塑機(jī)的選擇合適并且對(duì)鎖模力等進(jìn)行校核。原始數(shù)據(jù):測(cè)繪冰露礦泉水瓶蓋,并繪制原始圖樣。
工作量要求:
課題實(shí)施辦法:
1、 在理解任務(wù)書后,按要求完成開題報(bào)告一份;
2、 根據(jù)本專業(yè)或者和本專業(yè)相近的專業(yè),查閱外文資料完成外文資料譯文(約3000漢字)一篇;
3、 完成畢業(yè)設(shè)計(jì)論文(4000字左右)一篇,其中中文摘要300漢字左右,外文摘要約250個(gè)詞左右;
4、 將畢業(yè)設(shè)計(jì)期間所有的設(shè)計(jì)思想和遇到的困難及解決辦法都要在設(shè)計(jì)任務(wù)書中體現(xiàn)出來(lái);
畢 業(yè) 設(shè) 計(jì)(論 文)任 務(wù) 書
3.對(duì)本畢業(yè)設(shè)計(jì)(論文)課題成果的要求〔包括圖表、實(shí)物等硬件要求〕:
工作量要求:
1、完成冰露礦泉水瓶瓶蓋螺紋伺服脫模模具設(shè)計(jì)設(shè)計(jì)說(shuō)明書一份;
2、完成冰露礦泉水瓶瓶蓋螺紋伺服脫模模具設(shè)計(jì)裝配圖和零件圖若干;
3、完成裝配圖與部分零件圖總圖量:累加起來(lái)達(dá)到A0圖紙2張;
4.主要參考文獻(xiàn):
[1]齊衛(wèi)東主編。塑料模具設(shè)計(jì)與制造.北京:高等教育出版社,2004
[2]張利平主編.液壓傳動(dòng)設(shè)計(jì)指南[M].第1版.北京:化學(xué)工業(yè)出版社,2012.4 [3][3]鄧明主編.實(shí)用模具設(shè)計(jì)簡(jiǎn)明手冊(cè)[M].第1版.北京:機(jī)械工業(yè)出版社,2010.1
[4]CSCD核心期刊.機(jī)械設(shè)計(jì)[J].天津.中國(guó)科學(xué)技術(shù)協(xié)會(huì).12-1120/TH
[5]Watson I. Case-based reasoning is a methodology not a technology[J].K now ledge-Based Systems , 1999.12(5-6) : 303-308
[6] W.J.Dan, W.G. Zhang, S.H. Li and Z.Q. Lin. An experimental investigation oflarge-strain tensile behavior of a metal sheet[J].Materials &Design,2007,28:2190~2196
[7] Wilson,F(xiàn).W.Die design handbook MaGraw Hill 1990.6
畢 業(yè) 設(shè) 計(jì)(論 文)任 務(wù) 書
5.本畢業(yè)設(shè)計(jì)(論文)課題工作進(jìn)度計(jì)劃:
起 訖 日 期
工 作 內(nèi) 容
起 訖 日 期
工 作 內(nèi) 容
2019年12月18日-2019年12月20日
指導(dǎo)教師下發(fā)任務(wù)書,師生見面討論、并當(dāng)面給學(xué)生分配設(shè)計(jì)任務(wù)
2019年12月23日-2020年3月2日
學(xué)生搜集資料,提交開題報(bào)告及外文翻譯的初稿
2020年3月9日-2020年3月17日
提交開題報(bào)告、外文參考資料及譯文的修改稿
2020年3月18日-2020年3月30日
進(jìn)一步完善前期的各項(xiàng)材料,提交各項(xiàng)材料的定稿,開始準(zhǔn)備畢業(yè)設(shè)計(jì)的課題研究
2020年4月1日-2020年4月8日
進(jìn)行畢業(yè)設(shè)計(jì)中期檢查,學(xué)生進(jìn)行課題的設(shè)計(jì)、編程、安裝、調(diào)試
2020年4月9日-2020年5月18日
學(xué)生進(jìn)一步完善課題的設(shè)計(jì)、編程、安裝、調(diào)試,教師評(píng)閱學(xué)生畢業(yè)設(shè)計(jì);學(xué)生準(zhǔn)備畢業(yè)設(shè)計(jì)答辯
所在專業(yè)審查意見:
同意
專業(yè)(系)負(fù)責(zé)人:
2019年12月26日
學(xué)院審查意見:
同意
學(xué)院負(fù)責(zé)人:
2020年1月8日
畢業(yè)設(shè)計(jì)(論文)外文資料翻譯
設(shè)計(jì)(論文)題目: 冰露礦泉水瓶瓶蓋螺紋伺服脫模模具設(shè)計(jì)
學(xué)生姓名:
學(xué) 院: 機(jī)械與電氣工程學(xué)院
專 業(yè):
班 級(jí):
學(xué) 號(hào):
指導(dǎo)教師:
外文出處:
年2月27日
1.外文資料翻譯譯文(約3000漢字):
注塑件模擬焊縫成形的實(shí)驗(yàn)驗(yàn)證
J.G. Kovács*, B. Sikló
布達(dá)佩斯技術(shù)經(jīng)濟(jì)大學(xué)高分子工程系
摘要:近幾年來(lái),由于對(duì)注塑件性能要求的不斷提高,人們對(duì)注塑件的焊縫分析越來(lái)越感興趣。當(dāng)兩個(gè)熔化前沿相互接觸時(shí)形成焊縫。如果不修改零件的幾何結(jié)構(gòu),就不可能完全消除焊縫,但可以將其對(duì)零件性能和外觀的負(fù)面影響降到最低。這可以通過(guò)試錯(cuò)實(shí)驗(yàn)或模型預(yù)測(cè)來(lái)實(shí)現(xiàn)。后者的成本和時(shí)間效率使其成為焊縫分析的首選方法。注射成形計(jì)算機(jī)模擬軟件包能夠準(zhǔn)確預(yù)測(cè)焊縫位置,但現(xiàn)有的軟件包都不能定量預(yù)測(cè)焊縫接觸角和力學(xué)性能。本文對(duì)焊縫成形過(guò)程進(jìn)行了分析,提出了改進(jìn)有限元網(wǎng)格的方法,以獲得較好的效果。
關(guān)鍵詞:焊縫;注塑成型;模擬;有限元網(wǎng)格
1、介紹
注塑成型是用于成型塑料零件的最有效的工藝之一[1–6]。該方法的有效性取決于產(chǎn)品的質(zhì)量,這可能會(huì)受到工藝設(shè)置不足或模具結(jié)構(gòu)造成各種缺陷的阻礙。許多缺陷如焊縫、翹曲、噴射或凹陷等都會(huì)降低注塑件的質(zhì)量,降低生產(chǎn)效率。在注塑件的設(shè)計(jì)中,焊縫的產(chǎn)生是一個(gè)重要的美學(xué)和機(jī)械問題。當(dāng)兩個(gè)熔化前沿相互接觸時(shí)形成焊縫。在具有多個(gè)澆口的零件中,在模具填充過(guò)程中,可變壁厚、孔或型芯形成單獨(dú)的熔體前沿,而分離的熔體前沿形成焊縫,從而在零件中造成許多故障[7,8]。它不僅惡化了局部的機(jī)械性能,而且會(huì)產(chǎn)生光學(xué)缺陷,特別是在使用高光澤材料時(shí)。Chen等人在ABS拉伸鋼筋上研究了感應(yīng)加熱在表面溫度控制中的應(yīng)用,消除了焊縫表面的痕跡 [9]。 的確許多參數(shù)對(duì)焊縫的性能有影響,這些因素已經(jīng)從多個(gè)方面進(jìn)行了研究。在力學(xué)性能方面,對(duì)焊縫強(qiáng)度和模量進(jìn)行了分析,結(jié)果表明焊縫對(duì)拉伸模量沒有顯著影響[10,11]。一些研究人員[12-15]使用焊縫系數(shù)(WL factor),定義為:有焊縫的試樣強(qiáng)度/沒有焊縫的試樣強(qiáng)度,來(lái)評(píng)估他們的實(shí)驗(yàn)。采用高熔體溫度、高保壓壓力和低結(jié)晶器溫度對(duì)未填充材料的影響系數(shù)最高。利用激光引伸計(jì)和聲發(fā)射對(duì)焊縫進(jìn)行了研究,得出的結(jié)論是焊縫不是材料中的簡(jiǎn)單不連續(xù),而是應(yīng)力應(yīng)變分布的局部擴(kuò)展擾動(dòng)[16]。
近年來(lái),由于對(duì)注塑件性能要求的不斷提高,人們對(duì)注塑件焊縫分析的興趣大大增加。如果不修改零件的幾何結(jié)構(gòu),就不可能完全消除焊縫,但可以將其對(duì)零件性能和外觀的負(fù)面影響降到最低。這可以通過(guò)試錯(cuò)實(shí)驗(yàn)或模型預(yù)測(cè)來(lái)實(shí)現(xiàn)。后者的成本和時(shí)間效率使其成為焊縫分析的首選方法。注射成型計(jì)算機(jī)模擬軟件包能夠準(zhǔn)確預(yù)測(cè)焊縫位置,但現(xiàn)有的軟件包都不能定量預(yù)測(cè)焊縫性能。這主要是因?yàn)槠駷橹?,焊縫特性的數(shù)學(xué)模型不可用[17]。
在他們的文章中,周和李[17]提出了一個(gè)基于人工神經(jīng)網(wǎng)絡(luò)方法(ANN)的焊縫強(qiáng)度評(píng)估模型。對(duì)于網(wǎng)絡(luò)的輸入,選擇了影響焊縫性能的因素,即材料的取向系數(shù)、相遇角和熔體流動(dòng)歷史系數(shù)。與試驗(yàn)結(jié)果的比較表明,該模型能夠定量地預(yù)測(cè)焊縫性能,為工程設(shè)計(jì)提供了依據(jù)。Zhou等人 [18] 研究了熔體溫度和保壓對(duì)焊縫試件力學(xué)性能的影響,發(fā)現(xiàn)隨著保壓和熔體溫度的升高,焊縫試件的屈服強(qiáng)度和疲勞強(qiáng)度增加。他們解釋了觀察到的不同性質(zhì)的皮膚核心形態(tài),這是受熔體溫度和保持壓力的影響。
Au [19]使用幾何方法來(lái)生成塑料部件的填充圖案,并確定可能的焊接線的大致位置。Fathi和Behravesh[20]用可視化技術(shù)研究了焊縫成形過(guò)程中的流動(dòng)動(dòng)力學(xué)行為,而Zhou和Li[17]開發(fā)了一個(gè)人工網(wǎng)絡(luò)來(lái)預(yù)測(cè)焊縫性能。為了確定網(wǎng)絡(luò)的輸入?yún)?shù),對(duì)影響因素進(jìn)行了詳細(xì)的分析。對(duì)不可避免的焊縫非關(guān)鍵區(qū)域的形成和定位進(jìn)行了仿真分析。多澆口零件焊縫定位的流量控制采用流道尺寸調(diào)整方法[21]。Mezghani[22]將模擬的焊縫位置結(jié)果與注塑件的實(shí)際位置進(jìn)行了比較。Zhou和Li[23]提出了一種基于初始相遇節(jié)點(diǎn)特征的焊縫檢測(cè)算法。Chen[24]在零件仿真模型中應(yīng)用模糊理論,通過(guò)改變壁厚和澆口位置來(lái)控制焊縫位置。Chun[25]通過(guò)模擬研究了壁厚和澆口位置對(duì)焊縫形成和位置的影響。
2、實(shí)驗(yàn)
實(shí)驗(yàn)在Arburg Allrounder 320C 600-250注塑機(jī)上使用雙腔注射模進(jìn)行。這種特殊的模具有可更換的插入件,可以用不同的澆口類型(標(biāo)準(zhǔn)、薄膜、特殊薄膜等)具有不同的模具表面光潔度(拋光、細(xì)腐蝕、粗腐蝕),并注入不同厚度的試樣(0.5–4 mm)。樣品的厚度是由一個(gè)移動(dòng)的部分來(lái)設(shè)置的,以定位空腔的深度。注射模的頂出系統(tǒng)不同于傳統(tǒng)的頂出系統(tǒng),它不包括頂出銷,而是在整個(gè)零件表面積上工作,從而消除了試樣的變形。澆口類型可以隨插入型腔之間的嵌件的變化而變化,而無(wú)需從注塑機(jī)上拆下模具。實(shí)驗(yàn)中,采用了精細(xì)的腐蝕表面光潔度,并在模具中設(shè)置了雙標(biāo)準(zhǔn)澆口鑲塊。
每個(gè)零件的標(biāo)稱尺寸為80 mm×80mm×2mm,從兩點(diǎn)注射成型。兩個(gè)標(biāo)準(zhǔn)澆口位于腔的一側(cè),距零件邊緣10 mm,相距60 mm。
采用聚酰胺6(Durethan B30S,Lanxess)進(jìn)行研究。在注射成型之前,材料在80℃注射工藝條件保持恒定,模具溫度為90℃, 當(dāng)熔體溫度設(shè)定在280℃ 使用不同的切換點(diǎn)設(shè)置使用短射技術(shù)制作試樣。在樣品上測(cè)量熔體前沿的相遇角,作為流動(dòng)距離的函數(shù)。
測(cè)量結(jié)果繪制在圖5上。從中可以清楚地看出,會(huì)合角隨流長(zhǎng)的增加而增大。在7毫米的流動(dòng)距離,它達(dá)到了一個(gè)可測(cè)量的焊縫角約28°,當(dāng)距離為22毫米時(shí),角度為100°。在較長(zhǎng)的流動(dòng)中,由于熔體前沿的輪廓,無(wú)法測(cè)量會(huì)合角。
通過(guò)在澆口位置中心使用同心圓對(duì)熔體前沿進(jìn)行可視化,還構(gòu)建了會(huì)合角。結(jié)果表明,拉伸會(huì)合角的增加沒有測(cè)量值高。在理論流動(dòng)距離為10毫米時(shí),它很好地代表了測(cè)量值,但在較長(zhǎng)的距離時(shí),它低估了實(shí)驗(yàn)尺度。
3、分析
有限元模擬注射成型是目前設(shè)計(jì)注射模最先進(jìn)的技術(shù)。市場(chǎng)上有不同級(jí)別的節(jié)目。這些基礎(chǔ)知識(shí)對(duì)產(chǎn)品設(shè)計(jì)有一定的幫助,可以在不了解塑料制造的情況下使用。更復(fù)雜的程序能夠模擬整個(gè)注射成型過(guò)程,這樣人們就可以看到模具是否能夠完美工作。這種軟件覆蓋了大量的材料和機(jī)械數(shù)據(jù)庫(kù),設(shè)計(jì)者必須具備塑料制造的專業(yè)知識(shí)。
對(duì)于注塑模擬,在大多數(shù)情況下,采用二維三角形單元或三維四面體單元來(lái)描述型腔,其中兩節(jié)點(diǎn)管單元用于流道、連接件和通道。用控制體積法計(jì)算了熔體前沿的變化。在每一步中都可以得到壓力場(chǎng)、溫度場(chǎng)和速度場(chǎng)。這些結(jié)果構(gòu)成了應(yīng)力和變形分析以及焊縫結(jié)果的基礎(chǔ)。
Moldflow Plastics Insight 6.2用于模擬分析實(shí)驗(yàn)中使用的零件模型。在分析過(guò)程中,使用了三種不同的中間平面網(wǎng)格類型:原始網(wǎng)格、理想網(wǎng)格和平滑網(wǎng)格。每種網(wǎng)格類型在4個(gè)網(wǎng)格邊長(zhǎng)度中完成:1、2、2.5和5 mm。
原始網(wǎng)格是指模型由等邊三角形組成,沿估計(jì)焊縫的節(jié)點(diǎn)不產(chǎn)生直線。這種網(wǎng)格類型的優(yōu)點(diǎn)是具有良好的長(zhǎng)寬比。網(wǎng)格單元的長(zhǎng)寬比非常重要,因?yàn)樗绊懡Y(jié)果的精度。比率定義了三角形的最長(zhǎng)邊與三角形面積之間的相關(guān)性,而中面網(wǎng)格的推薦最大縱橫比為約6。可以看出,在每一條邊的長(zhǎng)度上,這種網(wǎng)格三角形的平均長(zhǎng)寬比都大于1.5。
理想網(wǎng)格由具有共線節(jié)點(diǎn)的等腰三角形構(gòu)成。生成這種網(wǎng)格類型的優(yōu)點(diǎn)是,它可以很好地自動(dòng)化,但是,由于較差的縱橫比,即2,它不如原始網(wǎng)格那樣精確。在平滑網(wǎng)格的情況下,原始網(wǎng)格的節(jié)點(diǎn)收斂形成一條線,在預(yù)測(cè)的焊縫區(qū)域中創(chuàng)建網(wǎng)格三角形邊的更均勻路徑。它是從原始網(wǎng)格類型生成的,并在焊縫區(qū)域進(jìn)行了修改。將焊縫上的節(jié)點(diǎn)靠近理想焊縫位置。
模擬分析的工藝設(shè)置與實(shí)驗(yàn)注射成型相同,模具恒溫,熔體溫度為90℃和280℃。
焊縫分析結(jié)果與實(shí)驗(yàn)結(jié)果進(jìn)行了比較。在大多數(shù)情況下,理想的網(wǎng)格類型最適合測(cè)量結(jié)果。在邊長(zhǎng)為1mm的情況下,采用理想和平滑網(wǎng)格類型的分析接近于流量長(zhǎng)度為7-10mm之間的測(cè)量結(jié)果。原始網(wǎng)格類型計(jì)算的值沿整個(gè)檢測(cè)流長(zhǎng)在測(cè)量結(jié)果周圍波動(dòng),不接近測(cè)量值,而其他網(wǎng)格類型與流動(dòng)開始時(shí)的測(cè)量值不同。同時(shí)觀察到,在距離為10 mm后,所有網(wǎng)格都預(yù)測(cè)出焊縫角急劇增加。
當(dāng)網(wǎng)格長(zhǎng)度為2 mm且流動(dòng)距離較短時(shí),振動(dòng)再次明顯。與測(cè)量結(jié)果相比,原始網(wǎng)格給出的結(jié)果最不準(zhǔn)確。角度值變化較大:計(jì)算出焊縫角為0°距離10.6毫米但147°12毫米。除原始網(wǎng)格外,在較長(zhǎng)的流動(dòng)路徑下與測(cè)量結(jié)果的差異小于在邊緣長(zhǎng)度為2 mm時(shí)的差異。
邊緣長(zhǎng)度增加到2.5mm,測(cè)量結(jié)果和模擬結(jié)果之間的相似性降低。在流動(dòng)距離為15~20 mm的區(qū)域,用理想網(wǎng)格模擬計(jì)算的焊縫線角與實(shí)測(cè)值接近,但其它網(wǎng)格變化不符合實(shí)測(cè)值的變化趨勢(shì)。
使用5 mm的邊緣長(zhǎng)度,曲線之間的一致性很弱。盡管分析結(jié)果顯示出一些相似性,但出乎意料的是,結(jié)果僅在少數(shù)流動(dòng)長(zhǎng)度下接近測(cè)量值。
比較每個(gè)邊緣長(zhǎng)度處的不同網(wǎng)格類型,可以注意到在每種情況下,理想網(wǎng)格與測(cè)量數(shù)據(jù)的相關(guān)性最好,在0.95和0.98之間變化。結(jié)果還表明,理想網(wǎng)格的最佳相關(guān)度在高邊長(zhǎng)處,即5mm處,但隨著邊長(zhǎng)的減小,相關(guān)度降低的幅度相對(duì)較小。對(duì)于原始網(wǎng)格類型,相關(guān)性最低,但隨著邊緣長(zhǎng)度的增加,相關(guān)性顯著提高,但這種網(wǎng)格類型并沒有達(dá)到理想的相關(guān)性值。使用平滑網(wǎng)格,相關(guān)度隨著邊緣長(zhǎng)度的增加而提高,但也沒有達(dá)到理想網(wǎng)格類型的值。
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2.外文資料原文(與課題相關(guān),至少1萬(wàn)印刷符號(hào)以上):
Experimental validation of simulated weld line formation in injection moulded parts
J.G. Kovács*, B. Sikló
Abstract:The interest in weld line analysis of injection-moulded parts has increased in the past few years, mainly because of the ever-increasing requirements for the performance of injec- tion-moulded items. Weld lines are formed when two melt fronts come in contact with each other. Whereas the total elimination of weld lines is not always possible without modifying the part geometry, their negative in?uence on part performance and appear- ance can be minimized. This can be done by trial and error experiments or by model prediction. The cost and time ef?ciency of the latter makes it a preferred route for weld lines analysis. Computer simulation packages of injection moulding are capable of accu- rately predicting the weld line location, but none of the current ones can predict the weld line contact angle or mechanical properties quantitatively. This paper focuses on the analysis of weld line formation and suggests ways to modify the ?nite element mesh to get better results.
Keywords:Weld line ;Knit line;Injection moulding ;Simulation;Finite element mesh
1.Introduction
Injection moulding is one of the most productive processes used to form plastic parts [1–6]. The effectiveness of the method depends on the quality of the product, which can be hindered by inadequate process settings or mould construction causing various de?ciencies. Many kind of defect such as weld lines, warpage, jetting or sink marks can reduce the quality of the injection moulded parts, worsening productivity. The occurrence of a weld line means a signi?cant problem both aesthetically and mechanically in the design of injection moulded parts.
Weld lines are formed when two melt fronts come in contact with each other. In a part with multiple gates, variable wall thicknesses, holes or cores form separate melt fronts during mould ?lling and the separated melt fronts create weld lines, causing numerous troubles in the part [7,8]. It not only worsens the local mechanical properties, but creates optical imperfections, especially when using high gloss materials. The surface marks of weld lines can be eliminated by the application of induction heating in surface temperature control, which was investigated on ABS tensile bars by Chen et al. [9].
Many parameters have an effect on the properties of a weld line and these factors have been investigated from many aspects. As regards mechanical properties, analysis of weld line strength and modulus was performed and showed that the weld line did not have a signi?cant effect on tensile modulus [10,11]. Several researchers [12–15] used the weld line factor (WL-factor), de?ned as: strength of specimens with weld line/strength of specimens without weld line, to evaluate their experiments. Highest WL- factors were obtained for un?lled materials and using high melt temperature, high holding pressure and low mould temperature. Weld lines were studied using laser exten- someter and acoustic emission, and the conclusion was that a weld line is not a simple discontinuity in the material, but a locally extended disturbance of the stress and strain distribution [16].
The interest in weld line analysis of injection-moulded parts has increased greatly in the past few years, mainly because of the ever-increasing requirements for the performance of injection-moulded items. Whereas the total elimination of weld lines is not always possible without modifying the part geometry, their negative in?uence on part performance and appearance can be minimized. This can be done by trial and error experiment or by model prediction. The cost and time ef?ciency of the latter makes it a preferred route for weld line analysis. Computer simulation packages of injection moulding are capable of accurately predicting the weld line location, but none of the current ones can predict the weld line prop- erties quantitatively. This is mainly because a mathematical model for weld line properties is, to date, unavailable [17].
In their article, Zhou and Li [17] presented an evaluation model for weld line strength based on the arti?cial neural network method (ANN). For the input of the network, the factors affecting weld line properties were chosen; those are the orientation coef?cient of the material, the meeting angle and the melt mobility history coef?cient. Comparison with experimental results shows that the presented model is capable of predicting weld line properties quantitatively for engineering design. Zhou et al. [18] examined the effects of melt temperature and hold pressure on the mechanical properties of specimens with weld lines and found that the yield and fatigue strengths of the specimens increased with increasing hold pressure as well as increasing melt temperature. They explained the observed differences in properties in terms of a skin-core morphology, which was in?uenced by both the melt temperature and the holding pressure.
Au [19] used a geometrical approach to generate the ?lling patterns of plastic parts and determine the approx- imate location of possible weld lines. Fathi and Behravesh[20] studied the kinematical behaviour of the ?ow during weld formation with a visualization technique, while Zhou and Li [17] developed an arti?cial network to predict weld line properties. The affecting factors were analyzed in detail in order to identify the input parameters for the network. The formation and positioning in noncritical areas of unavoidable weld lines are also investigated with simula- tion analyses. The controlling of the ?ow for weld line positioning for multi-gated parts was carried out with a runner resizing method [21]. Mezghani [22] compared the simulated weld line location results with the real position on injection moulded parts. Zhou and Li [23] presented a weld detector algorithm, which is based on the characteristics of the initial meeting node. Chen [24] applied fuzzy theory for controlling the weld line position by varying the wall thickness and the gate location in part simulation models. Chun [25] showed by simulation the effect of wall thickness and gate location on the formation and position of weld lines.
2.Experimental
The experiments were performed on an Arburg Allrounder 320C 600-250 injection moulding machine using a two cavity-injection mould (Fig. 1.). This special mould has changeable inserts to be able to inject with different gate types (standard, ?lm, special-?lm, multi gates, etc.), with different mould surface ?nishes (polished, ?ne eroded, rough eroded) and to inject different thickness specimens (0.5–4 mm). The thickness of the samples is set by a moving part to position the depth of the cavities. The ejection system of the injection mould differs from the conventional one; it does not include ejector pins but operates on the whole part surface area, so eliminating deformation of the sample. The gate type can be varied with the change of an insert interposed between the cavi- ties without dismounting the mould from the injection moulding machine. For the experiments, a ?ne eroded surface ?nish was used and an insert with double standard gates was set in the mould.
Each part, having nominal dimensions of 80 mm 80 mm 2 mm, was injection moulded from two points (Fig. 2.). The two standard gates are located on one side of the cavity 10 mm from the part edge and 60 mm apart.
Polyamide 6 (Durethan B30S, Lanxess) was used for the investigations. Before injection moulding, the material was dried at 80 ○C for 4 h. The injection processing conditions were kept constant; the mould temperature was 90 ℃while the melt temperature was set at 280 ○C. The speci- mens were produced with short shot technology using different switch-over point settings (Fig. 3.). The meeting angle of the melt front was measured on the samples as a function of the ?ow distance (Fig. 4.).
The results of the measurement are plotted on Fig. 5. It can be clearly seen that the meeting angle increased with the ?ow length. At a ?ow distance of 7 mm, it reached a measurable weld line angle of about 28○, while at a distance of 22 mm the angle achieved was 100○. At longer ?ows the measurement of the meeting angle was not possible because of the pro?le of the melt front.
The meeting angles were also constructed from the visualization of the melt fronts using concentric circles centred at the gate locations. The results showed that the increase of the drawn meeting angle was not as high as the measured values (Fig. 5.). At a theoretical ?ow distance of 10 mm it represented the measured values well but at a longer distance it underestimated the experimental scale.
3、Analysis
Injection moulding simulation with the ?nite element method is the most advanced technique for designing injection moulds. There are different levels of program available on the market. The basic ones are helpful in product design, which can be used without having deep knowledge of plastic manufacturing. The more complex programs are able to simulate the whole injection moulding process so one can see whether the mould will be able to work perfectly or not. Such software cover enor- mous databases of materials and machines and the designers must have professional knowledge of plastic manufacturing.
For an injection moulding simulation, in most cases two-dimensional triangular elements or three-dimensional tetrahedron elements are used to describe the cavity, with two-node tube elements for the runners, connectors and channels. The melt front advancements are calculated by the control volume method. The pressure, temperature and velocity ?eld can be obtained in each time step. These results constitute the basis of the stress and deformation analysis as well as results for weld lines.
Mold?ow Plastics Insight 6.2 was used for the simulation analyses with a model of the part used in the experiments (Fig. 6.). During the analyses, three different mid plane mesh types were used and compared: original mesh, ideal mesh and smoothed mesh. Each mesh type was completed in 4 mesh edge lengths: 1, 2, 2.5 and 5 mm.
Original mesh means that the model consists of equilateral triangles and the nodes along the estimated weld line did not produce a straight line. The advantage of this mesh type is the good aspect ratio. The aspect ratio of the mesh elements is important because it affects the accuracy of the results. The ratio de?nes the correlation between the longest side of the triangle and the triangle area, and the recommended maximum aspect ratio for a mid plane mesh is about 6. It can be seen that at every edge length this type of mesh triangle was greater than an average aspect ratio of 1.5.
Ideal mesh is made up of isosceles triangles with collinear nodes. The advantage of the generation of this mesh type is that it can be well automated, however, because of the worse aspect ratio, namely 2, it was not as accurate as the original mesh (Fig. 7). In the case of the
smoothed mesh, the nodes of the original mesh are converged to form a line creating a more uniform path of the mesh triangle sides in the area of the predicted weld line. It was generated from the original mesh type with modi?cation at the weld line region. The nodes positioned on the weld line were made nearer to the ideal weld line position.
The process settings for the simulation analyses were identical to the experimental injection moulding, constant mould temperature and melt temperature namely 90 ℃ and 280 ℃。
The weld line analysis results were compared to the experimental. In most cases, the ideal mesh type best ?tted the results of the measurements. At an edge length of 1 mm, the analyses with ideal and smoothed mesh type came close to the measurement results between flow lengths of 7 and 10 mm (Fig. 8.). The values calculated with original mesh type flucated