矩形骨架線圈注塑模設(shè)計(jì)【線圈骨架】【一模兩腔】【側(cè)抽芯】【說明書+CAD】
購買設(shè)計(jì)請(qǐng)充值后下載,資源目錄下的文件所見即所得,都可以點(diǎn)開預(yù)覽,資料完整,充值下載可得到資源目錄里的所有文件?!咀ⅰ浚篸wg后綴為CAD圖紙,doc,docx為WORD文檔,原稿無水印,可編輯。具體請(qǐng)見文件預(yù)覽,有不明白之處,可咨詢QQ:12401814
河南機(jī)電高等??茖W(xué)校畢業(yè)設(shè)計(jì)(論文)任務(wù)書系 部: 材料工程系 專 業(yè): 模具設(shè)計(jì)與制造 學(xué)生姓名: 學(xué) 號(hào): 設(shè)計(jì)(論文)題目: 骨架線圈注塑模設(shè)計(jì) 起 迄 日 期: 指 導(dǎo) 教 師: 2007年 3月 20日畢 業(yè) 設(shè) 計(jì)(論 文)任 務(wù) 書1本畢業(yè)設(shè)計(jì)(論文)課題來源及應(yīng)達(dá)到的目的:本設(shè)計(jì)來源于生活中的骨架線圈塑料件,要求設(shè)計(jì)一套塑料模具成型此零件。要求該模具設(shè)計(jì)簡單,成型容易,脫模容易,可以批量生成。要求有所設(shè)計(jì)模具的裝配圖和全部的零件圖(非標(biāo)準(zhǔn)件),有一個(gè)典型零件的加工工藝卡。通過此設(shè)計(jì),讓學(xué)生理解塑料模具設(shè)計(jì)與制造的過程,為以后的學(xué)習(xí)和工作打下了一定基礎(chǔ)。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):原始數(shù)據(jù) 內(nèi)容: 1.模具工藝規(guī)程的編制 2.注塑模結(jié)構(gòu)設(shè)計(jì) 3.模具的有關(guān)計(jì)算 4.模具加熱和冷卻系統(tǒng)的計(jì)算 5.模具閉合高度的確定 6.注塑機(jī)有關(guān)參數(shù)的校核 7.繪制模具總裝圖 8.模具的裝配與調(diào)試 要求:1. 塑料制件結(jié)構(gòu)工藝分析和注塑工藝方案確定2. 模具裝配圖及零件圖的繪制3. 完成主要模具零件的工藝規(guī)程編制4. 編寫設(shè)計(jì)說明書5. 用word文檔形式打印出說明書所在專業(yè)審查意見:負(fù)責(zé)人: 年 月 日系部意見:系領(lǐng)導(dǎo): 年 月 日河南機(jī)電高等??茖W(xué)校畢業(yè)設(shè)計(jì)評(píng)語學(xué)生姓名: 班級(jí): 學(xué)號(hào): 題 目:骨架線圈注塑模模具設(shè)計(jì) 綜合成績: 指導(dǎo)者評(píng)語: 指導(dǎo)者(簽字): 年 月 日畢業(yè)設(shè)計(jì)評(píng)語評(píng)閱者評(píng)語: 評(píng)閱者(簽字): 年 月 日答辯委員會(huì)(小組)評(píng)語: 答辯委員會(huì)(小組)負(fù)責(zé)人(簽字): 年 月 日骨架線圈注塑模設(shè)計(jì)緒 論隨著工業(yè)的發(fā)展,工業(yè)產(chǎn)品的品種和數(shù)量不斷增加。換型不斷加快。使模具的需要補(bǔ)斷增加。而對(duì)模具的質(zhì)量要求越來越高。模具技術(shù)在國民經(jīng)濟(jì)中的作用越來越顯得更為重要。模具是制造業(yè)的重要工藝基礎(chǔ),在我國,模具制造屬于專用設(shè)備制造業(yè)。中國雖然很早就開始制造模具和使用模具,但長期未形成產(chǎn)業(yè)。直到20世紀(jì)80年代后期,中國模具工業(yè)才駛?cè)氚l(fā)展的快車道。近年,不僅國有模具企業(yè)有了很大發(fā)展,三資企業(yè)、鄉(xiāng)鎮(zhèn)(個(gè)體)模具企業(yè)的發(fā)展也相當(dāng)迅速。雖然中國模具工業(yè)發(fā)展迅速,但與需求相比,顯然供不應(yīng)求,其主要缺口集中于精密、大型、復(fù)雜、長壽命模具領(lǐng)域。由于在模具精度、壽命、制造周期及生產(chǎn)能力等方面,中國與國際平均水平和發(fā)達(dá)國家仍有較大差距,因此,每年需要大量進(jìn)口模具。中國模具產(chǎn)業(yè)除了要繼續(xù)提高生產(chǎn)能力,今后更要著重于行業(yè)內(nèi)部結(jié)構(gòu)的調(diào)整和技術(shù)發(fā)展水平的提高。結(jié)構(gòu)調(diào)整方面,主要是企業(yè)結(jié)構(gòu)向?qū)I(yè)化調(diào)整,產(chǎn)品結(jié)構(gòu)向著中高檔模具發(fā)展,向進(jìn)出口結(jié)構(gòu)的改進(jìn),中高檔汽車覆蓋件模具成形分析及結(jié)構(gòu)改進(jìn)、多功能復(fù)合模具和復(fù)合加工及激光技術(shù)在模具設(shè)計(jì)制造上的應(yīng)用、高速切削、超精加工及拋光技術(shù)、信息化方向發(fā)展。近年,模具行業(yè)結(jié)構(gòu)調(diào)整和體制改革步伐加大,主要表現(xiàn)在,大型、精密、復(fù)雜、長壽命、中高檔模具及模具標(biāo)準(zhǔn)件發(fā)展速度高于一般模具產(chǎn)品;塑料模和壓鑄模比例增大;專業(yè)模具廠數(shù)量及其生產(chǎn)能力增加;“三資”及私營企業(yè)發(fā)展迅速;股份制改造步伐加快等。從地區(qū)分布來看,以珠江三角洲和長江三角洲為中心的東南沿海地區(qū)發(fā)展快于中西部地區(qū),南方的發(fā)展快于北方。目前發(fā)展最快、模具生產(chǎn)最為集中的省份是廣東和浙江,江蘇、上海、安徽和山東等地近幾年也有較大發(fā)展。 模具成型具有優(yōu)質(zhì),高產(chǎn),低消耗,低成本的特點(diǎn)。因而,在國民經(jīng)濟(jì)各個(gè)部門得到了極其廣泛的應(yīng)用。在模具成型中,塑料成型占很大的比重。由于塑料具有化學(xué)穩(wěn)定性好,電絕緣性強(qiáng),力學(xué)性能高,自潤滑,耐磨及相對(duì)密度小等獨(dú)特的優(yōu)異性能,成為工業(yè)部分必不可少的新型材料。 根據(jù)業(yè)內(nèi)專家預(yù)測,今年中國塑料模具市場總體規(guī)模將增加13%左右,到2005年塑料模具產(chǎn)值將達(dá)到460億元,模具及模具標(biāo)準(zhǔn)件出口將從現(xiàn)在的9000多萬美元增長到2005年的2億美元左右,產(chǎn)值在增長,也就意味著市場在日漸擴(kuò)大。相當(dāng)多的發(fā)達(dá)國家塑料模具企業(yè)移師中國,是國內(nèi)塑料模具工業(yè)迅速發(fā)展的重要原因之一。中國技術(shù)人才水平的提高和平均勞動(dòng)力成本低都是吸引外資的優(yōu)勢(shì),所以中國塑模市場的前景一片輝煌,這是塑料模具市場迅速成長的重要因素所在。大學(xué)三年的學(xué)習(xí)即將結(jié)束,畢業(yè)設(shè)計(jì)是其中最后一個(gè)實(shí)踐環(huán)節(jié),是對(duì)以前所學(xué)的知識(shí)及所掌握的技能的綜合運(yùn)用和檢驗(yàn)。隨著我國經(jīng)濟(jì)的迅速發(fā)展,采用模具的生產(chǎn)技術(shù)得到愈來愈廣泛的應(yīng)用。 據(jù)悉目前全世界年產(chǎn)出模具約650億美元,其中塑料模具約為260億美元。我國1999年模具總產(chǎn)值245億元其中塑料模具約為82億元,2000年近100億元。七類塑料模具中,注塑模具所占比例很大,約占全部塑料模具的80%左右。塑料模具的主要用戶是家用電器行業(yè)、汽車、摩托車行業(yè)、電子音像設(shè)備行業(yè)、辦公設(shè)備行業(yè)、建筑材料行業(yè)、信息產(chǎn)業(yè)及各種塑料制品行業(yè)等。目前國內(nèi)年需塑料模具約130-140億元,真中有30多億元仍靠進(jìn)口,進(jìn)口量最多的塑料模具有汽車摩托車飾件模具、大屏幕彩電殼模具、冰箱洗衣機(jī)模具、通訊及辦公設(shè)備塑殼模具、塑料異型材模具等。在完成大學(xué)三年的課程學(xué)習(xí)和課程、生產(chǎn)實(shí)習(xí),我熟練地掌握了機(jī)械制圖、機(jī)械設(shè)計(jì)、機(jī)械原理等專業(yè)基礎(chǔ)課和專業(yè)課方面的知識(shí),對(duì)機(jī)械制造、加工的工藝有了一個(gè)系統(tǒng)、全面的理解,達(dá)到了學(xué)習(xí)的目的。對(duì)于模具設(shè)計(jì)這個(gè)實(shí)踐性非常強(qiáng)的設(shè)計(jì)課題,我們進(jìn)行了大量的實(shí)習(xí)。經(jīng)過在新飛電器有限公司、洛陽中國一拖的生產(chǎn)實(shí)習(xí),我對(duì)于模具特別是塑料模具的設(shè)計(jì)步驟有了一個(gè)全新的認(rèn)識(shí),豐富了各種模具的結(jié)構(gòu)和動(dòng)作過程方面的知識(shí),而對(duì)于模具的制造工藝更是實(shí)現(xiàn)了零的突破。在指導(dǎo)老師的協(xié)助下和在工廠師傅的講解下,同時(shí)在現(xiàn)場查閱了很多相關(guān)資料并親手拆裝了一些典型的模具實(shí)體,明確了模具的一般工作原理、制造、加工工藝。并在圖書館借閱了許多相關(guān)手冊(cè)和書籍,設(shè)計(jì)中,將充分利用和查閱各種資料,并與同學(xué)進(jìn)行充分討論,盡最大努力搞好本次畢業(yè)設(shè)計(jì)。 本次設(shè)計(jì)題目“骨架線圈的產(chǎn)品造型與模具設(shè)計(jì)”。該模具屬于側(cè)向抽芯的注射模。本說明書將分項(xiàng)闡述該塑件注射成型和模具設(shè)計(jì)的全過程。 由于本人設(shè)計(jì)水平有限,錯(cuò)誤的不妥之處在所難免,肯請(qǐng)老師批評(píng)指正。 第1章 模塑工藝規(guī)程的制定1.1塑件的工藝性分析(1) 材料性能分析 骨架線圈選用ABS塑料成型,ABS是一種具有良好綜合性能的工程塑料,它具有聚苯乙烯的良好成型性,聚丁二稀的韌性,聚丁烯腈的化學(xué)穩(wěn)定性和表面硬度,其抗拉強(qiáng)度可達(dá)35-50MPa。ABS粘度適中,流動(dòng)性好。它的另一個(gè)優(yōu)點(diǎn)是耐氣候性,其制品的使用溫度范圍為,適應(yīng)性廣。 ABS塑料具有一定的吸濕性,含水量為0.3%-0.8%,成型時(shí)在會(huì)在制品上產(chǎn)生斑痕、云紋、氣泡等缺陷,在注塑成型之前應(yīng)進(jìn)行干燥處理。ABS粘度適中、流動(dòng)性好。 ABS塑料密度1.08g/,彈性模量E=1.410MPa,成型收縮率=0.5%0.8%,泊松比。(2)注塑制件結(jié)構(gòu)和尺寸精度及表面質(zhì)量分析1結(jié)構(gòu)分析 從零件圖上分析,該零件總體形狀為矩形,在上、下兩端各有一個(gè)凸翼,其厚度為1.5mm,中間部分為16mm12mm11mm的矩形柱,因此,模具設(shè)計(jì)時(shí)必須設(shè)置側(cè)向分型抽芯機(jī)構(gòu),該零件屬于中等復(fù)雜程度。 2 尺寸精度 該零件各個(gè)尺寸均為注明公差,為提高經(jīng)濟(jì)效益,則按未注明公差尺寸來處理,根據(jù)表214查得ABS材料的適用未注公差等級(jí)為MT5級(jí),對(duì)應(yīng)的模具相關(guān)零件的尺寸加工容易保證。從塑件的壁厚來看,各處壁厚均為1.5mm,均勻一致,有利于零件成型。3零件質(zhì)量的分析 零件表面及內(nèi)腔要求沒有缺陷、毛刺,內(nèi)部不得有導(dǎo)電介質(zhì),沒有其他特別的表面質(zhì)量要求,故比較容易實(shí)現(xiàn)。 綜上分析可以看出,注塑時(shí)在工藝參數(shù)控制較好的情況下,零件的成型要求可1.2計(jì)算塑件的體積和質(zhì)量 計(jì)算塑件的質(zhì)量是為了選用注塑機(jī)及確定模具型腔數(shù)。 計(jì)算塑件的體積:用體積分割法求得V=2522.514-1310.514-164.5112-22.54.5112=2153計(jì)算塑件的質(zhì)量:根據(jù)設(shè)計(jì)手冊(cè)查得ABS的密度為=1.0g/,故塑件的質(zhì)量為:W=V =21531.0=2.2g1.3注塑模結(jié)構(gòu)分析與注塑機(jī)的選用 根據(jù)以上計(jì)算,采用一模兩件的結(jié)構(gòu)設(shè)計(jì),考慮其外形尺寸,注塑時(shí)所需壓力和工廠現(xiàn)有設(shè)備等情況,初步選用注塑機(jī)YS-ZY-45型。1.4塑件注塑工藝參數(shù)的確定 查找相關(guān)文獻(xiàn)和參考工廠實(shí)際應(yīng)用的情況,ABS的成型工藝參數(shù)可作如下選擇:(適模時(shí),可根據(jù)實(shí)際情況作適當(dāng)調(diào)整)預(yù)干燥溫度:7080 時(shí)間:2h注塑溫度:前段溫度t選用200; 中段溫度t選用220; 后段溫度t選用190; 噴嘴溫度:選用180;注塑壓力:選用80MPa;注塑時(shí)間:選用15S;保 壓:選用65 MPa;保壓時(shí)間:選用10s;冷卻時(shí)間:選用15s;第2章 注塑模的結(jié)構(gòu)設(shè)計(jì)注塑模的結(jié)構(gòu)設(shè)計(jì)主要包括:分型面的選擇、模具型腔數(shù)目的確定、型腔的排列方式、冷卻水道布局、模具工作零件的結(jié)構(gòu)設(shè)計(jì)、側(cè)向分型與抽芯機(jī)構(gòu)的設(shè)計(jì)、推出機(jī)構(gòu)的設(shè)計(jì)等內(nèi)容。2.1分型面的選擇 模具設(shè)計(jì)中,分型面的選擇很關(guān)鍵,它決定了模具的結(jié)構(gòu)。應(yīng)根據(jù)分型面選擇原則和塑件的成型來選擇分型面.該塑料表面質(zhì)量無特殊要求。但是在繞線的過程中,兩端凸翼與工人的手指接觸較多,因此兩端應(yīng)自然形成圓角;此外,該零件高度為14mm,且垂直于軸線的截面形狀比較簡單,可選用如下圖所示的水平分型方式,即可降低模具的復(fù)雜程度,減少模具加工難度,又便于成型取件。型面選擇如下圖。2.2確定型腔的排列方式本塑件在注塑時(shí)采用一模兩件,即模具需要兩個(gè)型腔,綜合考慮澆注系統(tǒng)、模具結(jié)構(gòu)的復(fù)雜程度等因素,擬采用型腔布置圖1所示的型腔排列方式。其最大優(yōu)點(diǎn)是便于設(shè)置側(cè)向分型抽芯機(jī)構(gòu),缺點(diǎn)是熔料進(jìn)入型腔后到另一端的料流長度較長,但是塑件尺寸較小,故對(duì)成型沒有太大的影響。 若采用其他的型腔排列方式,顯然料流長度較短,但是會(huì)增大側(cè)向抽的距離,勢(shì)必會(huì)增大模具整體尺寸。2.3澆注系統(tǒng)設(shè)計(jì)(1)主流道的設(shè)計(jì)根據(jù)設(shè)計(jì)手冊(cè)查得XSZ30型注塑機(jī)噴嘴的有關(guān)尺寸:噴嘴前端孔直徑: =2mm;噴嘴前端球面半徑:=12mm;根據(jù)模具主流道與噴嘴的關(guān)系:=+(12)mm D=+(0.51)mm取主流道球面半徑R=14mm;主流道的小端直徑d= 2.5mm.為了便于將凝料從主流道中拔出,將主流道設(shè)計(jì)成錐形,其斜度為。經(jīng)換算得主流道大端直徑D=4.5mm,為了使熔料順利進(jìn)入分流道,可在主流道出料端設(shè)計(jì)半徑r=5mm的圓弧過渡。(2) 分流道設(shè)計(jì)分流道的形狀及尺寸,應(yīng)根據(jù)塑件的體積、壁厚、形狀的復(fù)雜程度,注塑速度、分流道長度等因素來確定。本塑件形狀簡單對(duì)成,熔料填充型腔比較容易,根據(jù)型腔的排列方式,可知分流道長度較短,為便于加工起見,選截面形狀為梯形的分流道,根據(jù)制件壁厚、體積和形狀等,初確定梯形尺寸=4mm,=2.5mm,=1mm.(1) 澆口設(shè)計(jì)根據(jù)塑件的成型要求、型腔的排列方式及模具結(jié)構(gòu),擬選側(cè)澆口較為理想,可使模具結(jié)構(gòu)簡單,澆口易去除,且不影響塑件外觀。設(shè)計(jì)時(shí)考慮壁厚為1.3處進(jìn)料,料由厚處往薄處流,而且再模具結(jié)構(gòu)上采用鑲拼式型腔、型芯,有利于填充,排氣。采用截面為矩形的側(cè)澆口,查表初選尺寸為(blh)1mm0.8mm0.6mm,試模時(shí)修正。2.4抽芯機(jī)構(gòu)設(shè)計(jì)塑件的兩端各有一個(gè)凸翼,他們均垂直于脫模方向,阻礙成型后塑件從模具脫出,因此成型小凸臺(tái)的零件必須設(shè)計(jì)成活動(dòng)的型芯,即須設(shè)置抽芯機(jī)構(gòu)。本模具采用斜導(dǎo)柱機(jī)構(gòu)。(1) 確定抽芯距抽芯距一般應(yīng)大于成型孔(或凸臺(tái))的深度,本題中凸臺(tái)高度為11.25mm,另加3mm的抽芯安全系數(shù),可取抽拔距=15mm。(2) 確定斜銷傾角斜導(dǎo)柱傾斜角是傾斜機(jī)構(gòu)的主要技術(shù)數(shù)據(jù)之一,它與抽拔力與抽芯距有直接關(guān)系。一般取=1525,在這里選用20。(3) 確定斜銷尺寸斜導(dǎo)柱的直徑取決于抽拔力及其傾斜角度,按公式計(jì)算,取斜導(dǎo)柱直徑d= 18mm,固定凸肩D=1.8d。斜導(dǎo)柱的長度根據(jù)抽芯距、固定端模板的厚度、斜銷直徑及斜角大小確定,其計(jì)算根據(jù)公式:=+由于上模座板的凸模固定板尺寸尚不確定,即=25mm,如果設(shè)計(jì)中有變化,則修正的長度,取D=32mm,取=92mm.(4)滑塊與導(dǎo)滑槽設(shè)計(jì)(a)滑塊與側(cè)型芯的連接方式設(shè)計(jì)。本題側(cè)向抽芯機(jī)構(gòu)主要是用于成型零件的側(cè)向孔合側(cè)向凸臺(tái),擬采用整體式結(jié)構(gòu),具體結(jié)構(gòu)見零件圖01。(b)滑塊的導(dǎo)滑方式。為使模具結(jié)構(gòu)緊湊,降低模具裝配復(fù)雜程度,擬采用整體式滑塊和整體式導(dǎo)向槽的形式。其結(jié)構(gòu)見裝配圖。(c)滑塊的導(dǎo)滑長度和定位裝置設(shè)計(jì)。導(dǎo)滑長度要保證側(cè)向抽芯后,滑塊與導(dǎo)滑槽的配合長度不小于其總長度的,滑塊的定位裝置采用彈簧滾珠形式(見裝配圖)。2.5成型零件設(shè)計(jì)(1) 凹模的結(jié)構(gòu)設(shè)計(jì)本模具采用一模兩件的結(jié)構(gòu)設(shè)計(jì),考慮加工難易程度和材料的價(jià)值利用等因素,凹模擬采用拼塊式結(jié)構(gòu),滑塊同時(shí)構(gòu)成凹模型腔,其結(jié)構(gòu)形式見下圖(2) 凸模的結(jié)構(gòu)設(shè)計(jì)凸模主要是與凹模相結(jié)合構(gòu)成模具型腔,其結(jié)構(gòu)形式見下圖。第3章 模具設(shè)計(jì)的有關(guān)計(jì)算本例中成型零件工作尺寸計(jì)算時(shí)均采用平均尺寸、平均收縮率、平均制造公差和平均磨損量來進(jìn)行計(jì)算。查表得ABS地收縮率S=0.50.8,故平均收縮率為0.5,考慮到工廠模具現(xiàn)有條件,模具制造公差取。1. 型腔、型芯工作尺寸計(jì)算類別序號(hào)模具零件名稱塑件尺寸計(jì)算公式型腔或型芯工作尺寸型腔的計(jì)算1凹?;瑝K250.25222.50.223110.1641.50.16型芯的計(jì)算5主型芯130.16610.50.162壓緊楔塊的設(shè)計(jì)和計(jì)算為使注塑過程中凹?;瑝K能閉合緊密,避免側(cè)向分型面產(chǎn)生毛刺以及使斜導(dǎo)柱免除型腔的側(cè)向推擠力,擬采用壓緊楔塊對(duì)凹模滑塊進(jìn)行鎖緊。本題因模具尺寸不大,所以采用將楔塊與定模板設(shè)計(jì)為一整體的結(jié)構(gòu),為避免干涉撞擊,楔塊楔角按照下式選取式中:斜導(dǎo)柱楔角;:斜導(dǎo)柱與斜孔之間的間隙;:楔塊壓緊高度;=10mm。計(jì)算結(jié)果圓整為表81推薦值 ,取=。2. 型腔滑塊底板厚度計(jì)算根據(jù)組合式型腔底板厚度計(jì)算公式進(jìn)行計(jì)算:式中:=13mm;=40Mpa;=13mm;=125mm (根據(jù)模具初選外形尺寸確定) ;=160Mpa(底板材料選用45鋼)。代入計(jì)算得:H=8.5mm??紤]模具整體結(jié)構(gòu)的協(xié)調(diào),取H=25mm。第4章 模具加熱與冷卻系統(tǒng)的計(jì)算 本塑件在注射過程中不要求有太高的模溫,因而模具上可不開設(shè)加熱系統(tǒng),是否需要冷卻系統(tǒng)可作如下計(jì)算。設(shè)定模具平均工作溫度為65用20常溫水作為模具冷卻介質(zhì),其出口溫度為25,產(chǎn)量為(處算2分鐘一套),0.27/h。1求塑件在每小時(shí)釋放的熱量Q,查有關(guān)文獻(xiàn)ABS單位若流量為3.98J/g.Q=WQ=0.273.98J/g=1.074610 J/2求冷卻水的體積流量VV=0.8510m/min由體積流量V查表可知所需的冷卻水管直徑非常小。由上述計(jì)算可知,因?yàn)槟>呙糠昼娝璧睦鋮s體積流量很小,故可不設(shè)冷卻系統(tǒng),依靠空冷的方式冷卻模具即可。 第5章 結(jié)構(gòu)與輔助零部件的設(shè)計(jì)1. 導(dǎo)柱的選用導(dǎo)柱選用帶頭導(dǎo)柱,由導(dǎo)柱直徑與模板外形尺寸關(guān)系,其尺寸選用1610025,材料選用20鋼。GB/T4169.4-1984其結(jié)構(gòu)形式如下圖1-5所示: 圖1-5 導(dǎo)柱的結(jié)構(gòu)形式 其導(dǎo)柱的安裝時(shí)與模板之間的配合的公差取IT7級(jí),安裝沉孔直徑比導(dǎo)柱直徑大(12)。2.導(dǎo)套的選用導(dǎo)套選用直導(dǎo)套,與導(dǎo)柱的配合。尺寸選1640,材料選用20鋼。GB/T4169.2-1984 其結(jié)構(gòu)形式如下圖1-6所示: 圖1-6 導(dǎo)套的結(jié)構(gòu)形式 導(dǎo)套與模板的安裝孔徑之間的配合公差I(lǐng)T7級(jí),安裝后下平面磨平。 該模具由于塑件的精度要求較低,可以采用兩根導(dǎo)柱即可滿足塑件的精度,兩根導(dǎo)柱,導(dǎo)套尺寸選用相同直徑,不對(duì)稱布置。其布置形式如零件圖定模固定板上所示。 第6章 模具閉合高度的確定在支撐和固定零件的設(shè)計(jì)過程中,根據(jù)經(jīng)驗(yàn)確定:定模座板:=25mm,上固定板:=25mm,下固定板:=40mm,支撐板: =25mm動(dòng)模座板6=25mm。根據(jù)推出行程和推出機(jī)構(gòu)的結(jié)構(gòu)尺寸確定墊塊:=50mm因而模具閉合高度 + 6=25mm+25mm+40mm+25mm+50mm+25mm=185mm第7章 注塑機(jī)有關(guān)參數(shù)的校核本模具的外形尺寸為100mm125mm155mm. XSZ30型注塑機(jī)模板最大安裝尺寸為200mm190mm,故能滿足模具的安裝要求。由上述計(jì)算模具的閉合高度=185mm,XSZ30型注塑機(jī)所允許模具的最小厚度=60mm,最大厚度=180mm,即模具滿足的安裝條件。經(jīng)查資料XSZ30型注塑機(jī)的最大開模行程S=160mm,滿足下式頂出塑件的要求:=14+35+10=59mm此外,側(cè)向分型抽芯距不是很大,因此不會(huì)過大增加開模距離,注塑機(jī)的開模行程足夠。經(jīng)驗(yàn)證,XSZ30型注塑機(jī)能滿足使用要求,故可采用第8章 塑料模的裝配、試模與維修 1模具裝配 模具設(shè)有斜滑塊機(jī)構(gòu),先安裝斜導(dǎo)柱,作為模具的裝配基準(zhǔn),裝配順序如下;(1) 裝配前按圖檢驗(yàn)主要工作零件及其零件的尺寸。(2) 將導(dǎo)柱8壓入定模固定板10中,保證兩導(dǎo)柱的對(duì)稱度。(3) 裝配型芯,將型芯固定在定模座板9上,保證垂直度。將座板9固定在固定板10上。(4) 將凹模壓入動(dòng)模固定板23中,保證垂直度。(5) 將側(cè)滑塊7裝在固定板的導(dǎo)滑槽上。(6) 以凹模為基準(zhǔn),斜導(dǎo)柱起導(dǎo)向定位作用,將側(cè)滑塊裝配在斜導(dǎo)柱上,使分型面密合。(7) 以凹模為基準(zhǔn)將動(dòng)?;鶞?zhǔn)板26固定在動(dòng)模故定板上。(8) 裝配其他輔助零件。(9) 裝配完成,試模。使配時(shí)以分型面密合作為模具的裝配基準(zhǔn) 2試模(1) 試模前,先對(duì)設(shè)備的油路,水路以及電路進(jìn)行檢查;(2)選取的原料必須合格,根據(jù)選用的工藝參數(shù)將料筒和噴嘴加熱;(3)開始試模時(shí),應(yīng)該先選擇選定的壓力,溫度和注塑時(shí)間的條件下成型,制品不符合要求然后按壓力,注塑時(shí)間,溫度, 這樣的先后順序變動(dòng),注意一次只改變一個(gè)參數(shù);(4) 在試模過程中作出詳細(xì)的記錄,并將結(jié)果填入試模記錄卡,注明模具是否合格,如果需要返修,提出返修意見;(5)通過不斷的試模和返修,生產(chǎn)出合格的制件后,將模具清理干凈,涂上防銹油,入庫。3 試??赡墚a(chǎn)生的問題及改善措施試模中所獲得的樣件是對(duì)模具整體質(zhì)量的一個(gè)全面反映。以檢驗(yàn)樣件來修正和驗(yàn)收模具,是塑料模具這種特殊產(chǎn)品的特殊性。首先,在初次試模中我們最常遇到的問題是根本得不到完整的樣件。常因塑件被粘附于模腔內(nèi),或型芯上,甚至因流道粘著制品被損壞。這是試模首先應(yīng)當(dāng)解決的問題。3.1 粘著模腔制品粘著在模腔上,是指塑件在模具開啟后,與設(shè)計(jì)意圖相反,離開型芯一側(cè),滯留于模腔內(nèi),致使脫模機(jī)構(gòu)失效,制品無法取出的一種反?,F(xiàn)象。其主要原因是:(1) 注射壓力過高,或者注射保壓壓力過高。(2) 注射保壓和注射高壓時(shí)間過長,造成過量充模。(3) 冷卻時(shí)間過短,物料未能固化。(4) 模芯溫度高于模腔溫度,造成反向收縮。(5) 型腔內(nèi)壁殘留凹槽,或分型面邊緣受過損傷性沖擊,增加了脫模阻力。3.2 粘著模芯(1) 注射壓力和保壓壓力過高或時(shí)間過長而造成過量充模。 (2) 冷卻時(shí)間過長,制件在模芯上收縮量過大。(3) 模腔溫度過高,使制件在設(shè)定溫度內(nèi)不能充分固化。(4) 機(jī)筒與噴嘴溫度過高,不利于在設(shè)定時(shí)間內(nèi)完成固化。(5) 可能存在不利于脫模方向的凹槽或拋光痕跡需要改進(jìn)。3.3粘著主流道(1) 閉模時(shí)間太短,使主流道物料來不及充分收縮。(2) 料道徑向尺寸相對(duì)制品壁厚過大,冷卻時(shí)間內(nèi)無法完成料道物料的固化。(3) 主流道襯套區(qū)域溫度過高,無冷卻控制,不允許物料充分收縮。(4) 主流道襯套內(nèi)孔尺寸不當(dāng),未達(dá)到比噴嘴孔大0.51 。(5) 主流道拉料桿不能正常工作。一旦發(fā)生上述情況,首先要設(shè)法將制品取出模腔(芯),不惜破壞制件,保護(hù)模具成型部位不受損傷。仔細(xì)查找不合理粘模發(fā)生的原因,一方面要對(duì)注射工藝進(jìn)行合理調(diào)整;另一方面要對(duì)模具成型部位進(jìn)行現(xiàn)場修正,直到認(rèn)為達(dá)到要求,方可進(jìn)行二次注射。3.4 成型缺陷當(dāng)注射成型得到了近乎完整的制件時(shí),制件本身必然存在各種各樣的缺陷,這種缺陷的形成原因是錯(cuò)綜復(fù)雜的,一般很難一目了然,要綜合分析,找出其主要原因來著手修正,逐個(gè)排出,逐步改進(jìn),方可得到理想的樣件。下面就對(duì)度模中常見的成型制品主要缺陷及其改進(jìn)的措施進(jìn)行分析。(1) 注射填充不足所謂填充不足是指在足夠大的壓力、足夠多的料量條件下注射不滿型腔而得不到完整的制件。這種現(xiàn)象極為常見。其主要原因有:a. 熔料流動(dòng)阻力過大這主要有下列原因:主流道或分流道尺寸不合理。流道截面形狀、尺寸不利于熔料流動(dòng)。盡量采用整圓形、梯形等相似的形狀,避免采用半圓形、球缺形料道。熔料前鋒冷凝所致。塑料流動(dòng)性能不佳。制品壁厚過薄。b. 型腔排氣不良這是極易被忽視的現(xiàn)象,但以是一個(gè)十分重要的問題。模具加工精度超高,排氣顯得越為重要。尤其在模腔的轉(zhuǎn)角處、深凹處等,必須合理地安排頂桿、鑲塊,利用縫隙充分排氣,否則不僅充模困難,而且易產(chǎn)生燒焦現(xiàn)象。c. 鎖模力不足因注射時(shí)動(dòng)模稍后退,制品產(chǎn)生飛邊,壁厚加大,使制件料量增加而引起的缺料。應(yīng)調(diào)大鎖模力,保證正常制件料量。(2) 溢邊(毛刺、飛邊、批鋒)與第一項(xiàng)相反,物料不僅充滿型腔,而且出現(xiàn)毛刺,尤其是在分型面處毛刺更大,甚至在型腔鑲塊縫隙處也有毛刺存在,其主要原因有:a. 注射過量b. 鎖模力不足c. 流動(dòng)性過好d. 模具局部配合不佳e. 模板翹曲變形(3) 制件尺寸不準(zhǔn)確初次試模時(shí),經(jīng)常出現(xiàn)制件尺寸與設(shè)計(jì)要求尺寸相差較大。這時(shí)不要輕易修改型腔,應(yīng)行從注射工藝上找原因:a. 尺寸變大注射壓力過高,保壓時(shí)間過長,此條件下產(chǎn)生了過量充模,收縮率趨向小值,使制件的實(shí)際尺寸偏大;模溫較低,事實(shí)上使熔料在較低溫度的情況下成型,收縮率趨于小值。這時(shí)要繼續(xù)注射,提高模具溫度降低注射壓力,縮短保壓時(shí)間,制件尺寸可得到改善。b. 尺寸變小注射壓力偏低、保壓時(shí)間不足,制在冷卻后收縮率偏大,使制件尺寸變?。荒剡^高,制件從模腔取出時(shí),體積收縮量大,尺寸偏小。此時(shí)調(diào)整工藝條件即可。通過調(diào)整工藝條件,通常只能在極小范圍內(nèi)使尺寸京華,可以改變制件相互配合的松緊程度,但難以改變公稱尺寸。 c.調(diào)整措施 調(diào)整時(shí)應(yīng)注意調(diào)節(jié)進(jìn)料速度,增加排氣孔,正確設(shè)計(jì)澆注系統(tǒng)。注意控制成型周期。第9章 繪制模具總裝圖和非標(biāo)準(zhǔn)零件工作圖本模具的總裝圖見裝配圖所示。非標(biāo)準(zhǔn)件工作圖見零件圖。本模具的工作原理:模具安裝在注塑機(jī)上,定模部分固定在注塑機(jī)的定模板上,動(dòng)模固定在注塑機(jī)的動(dòng)模板上。合模后,注塑機(jī)通過噴嘴將熔料經(jīng)流道注入型腔,經(jīng)保壓、冷卻后塑件成型。開模時(shí)動(dòng)模部分隨動(dòng)模板一起運(yùn)動(dòng)漸漸將分型面打開,與此同時(shí)在斜導(dǎo)柱的作用下側(cè)滑塊向兩邊分離并脫離塑件,完成側(cè)向抽芯動(dòng)作,當(dāng)塑件完全脫離后,動(dòng)模停止運(yùn)動(dòng),在注塑機(jī)頂出裝置作用下,推動(dòng)推桿運(yùn)動(dòng)并驅(qū)動(dòng)脫件板將塑件從型芯上脫出。合模時(shí),隨著分型面的閉合側(cè)向滑塊復(fù)位至型腔,同時(shí)復(fù)位桿也對(duì)推桿進(jìn)行復(fù)位。第10章 注塑模主要零件加工工藝規(guī)程的編制1型芯機(jī)械加工工藝過程卡機(jī)械加工工藝過程卡片產(chǎn)品型號(hào)零(部)件圖號(hào)01產(chǎn)品名稱型芯零(部)件名稱型芯共(2)第(1)頁材料牌號(hào)45鋼毛坯種類圓棒料毛坯外型尺寸30每個(gè)毛坯可制件數(shù)4每臺(tái)件數(shù)4備注工序號(hào)工序名稱工 序 內(nèi) 容車間工段設(shè)備工 藝 裝 備工時(shí)準(zhǔn)終單件05下料鋸割下料30120下料車間鋸床0.510粗車車端面車削3680模具車間車床215精車車削至34.577.5模具車間車床220磨削磨削至34.0277.005模具車間磨床325鉗鉗工精修尺寸至要求工作表面拋光Ra0.1模具車間5.設(shè)計(jì)日期審核日期標(biāo)準(zhǔn)化日期會(huì)簽日期標(biāo)記記數(shù)更改文件號(hào)簽字日期標(biāo)記處數(shù)更該文件號(hào)2型腔機(jī)械加工工藝過程卡機(jī)械加工工藝過程卡片產(chǎn)品型號(hào)零(部)件圖號(hào)02產(chǎn)品名稱型腔零(部)件名稱共(3)頁第(3)頁材料牌號(hào) 45鋼毛坯種類鋼板毛坯外型尺寸10每個(gè)毛坯可制件數(shù)1每臺(tái)件數(shù)1備注工序號(hào)工序名稱工 序 內(nèi) 容車間工段設(shè)備工 藝 裝 備工時(shí)準(zhǔn)終單件05下料鋸割下料1050下料車間鋸床0.2510鍛造鍛至尺寸4015鍛造車間空氣錘215熱處理退火至180HBS200HBS模具車間820車削粗車至3212同上車床225精車精車至30110同上車床230線切割切割18的孔同上線切割機(jī)835熱處理成型部分淬火至要求同上8精修精修成型部分Ra0.2同上6設(shè)計(jì)日期審核日期標(biāo)準(zhǔn)化日期會(huì)簽日期標(biāo)記記數(shù)更改文件號(hào)簽字日期標(biāo)記處數(shù)更該文件號(hào)致 謝 塑料模具課程設(shè)計(jì)是塑料模具設(shè)計(jì)與制造課程重要的綜合性與實(shí)踐性教學(xué)環(huán)節(jié)。通過這次實(shí)際操作,使我能夠綜合運(yùn)用塑料模具設(shè)計(jì)課程和其他先修課程的知識(shí),分析和解決模具設(shè)計(jì)問題,進(jìn)一步鞏固、加深和拓寬所學(xué)知識(shí)。 通過設(shè)計(jì)實(shí)踐,我逐步樹立了正確的設(shè)計(jì)思想,增強(qiáng)了創(chuàng)新意識(shí),熟悉掌握塑料模具設(shè)計(jì)的一般規(guī)律,培養(yǎng)了分析問題和解決問題的能力;通過設(shè)計(jì)計(jì)算、繪圖以及運(yùn)用技術(shù)標(biāo)準(zhǔn)、規(guī)范、設(shè)計(jì)手冊(cè)等有關(guān)設(shè)計(jì)資料,進(jìn)行了全面的塑料模具設(shè)計(jì)基本技能的訓(xùn)練。從陌生到開始接觸,從了解到熟悉,這是每個(gè)人學(xué)習(xí)事物所必經(jīng)的一般過程,我對(duì)模具的認(rèn)識(shí)過程亦是如此。經(jīng)過近三個(gè)月的努力,我相信這次畢業(yè)設(shè)計(jì)一定能為三年的大學(xué)生涯劃上一個(gè)圓滿的句號(hào),為將來的事業(yè)奠定堅(jiān)實(shí)的基礎(chǔ)。在這次設(shè)計(jì)過程中得到了老師以及許多同學(xué)的幫助,特別是于智宏老師的悉心指導(dǎo),使我受益匪淺。在此,對(duì)關(guān)心和指導(dǎo)過我各位老師和幫助過我的同學(xué)表示衷心的感謝! 參考文獻(xiàn) 1. 楊占堯主編. 塑料注塑模結(jié)構(gòu)與設(shè)計(jì). 清華大學(xué)出版社. 2. 中國模具設(shè)計(jì)大典. 3. 王孝陪主編. 塑料成型工藝及模具簡明手冊(cè). 機(jī)械工業(yè)出版社. 20004. 模具制造手冊(cè)編寫組. 模具制造手冊(cè). 機(jī)械工業(yè)出版社. 19965. 馮炳堯,韓泰榮,蔣文生主編. 模具設(shè)計(jì)與制造簡明手冊(cè). 上海科學(xué)技術(shù)出版社,19986. 黃毅宏主編. 模具制造工藝. 機(jī)械工業(yè)出版社. 19997. 賈潤禮,程志遠(yuǎn)主編. 實(shí)用注塑模設(shè)計(jì)手冊(cè). 中國輕工業(yè)出版社. 20008. 唐志玉主編. 模具設(shè)計(jì)師指南. 國防工業(yè)出版社. 19999. 屈華昌主編. 塑料成型工藝與模具設(shè)計(jì). 機(jī)械工業(yè)出版社. 199510. 彭建聲主編. 簡明模具工實(shí)用技術(shù)手冊(cè). 機(jī)械工業(yè)出版社. 199327 編號(hào): 畢業(yè)設(shè)計(jì)(論文)外文翻譯(原文)院 (系): 國防生學(xué)院 專 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: 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 共 23 頁 桂林電子科技大學(xué)畢業(yè)(論文)報(bào)告專用紙 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