φ35×25蓋塞注塑模具設(shè)計(jì)
3525蓋塞注塑模具設(shè)計(jì),35×,25蓋塞注塑模具設(shè)計(jì),35,25,注塑,模具設(shè)計(jì)
沈陽(yáng)化工大學(xué)科亞學(xué)院本科畢業(yè)設(shè)計(jì) 題 目: 蓋塞注塑模具(3525) 專(zhuān) 業(yè): 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 班 級(jí): 1201 學(xué)生姓名: 王 磊 指導(dǎo)教師: 陳慧珍 論文提交日期:2016年6月1日論文答辯日期:2016年6月5日摘要模具是近代工業(yè)產(chǎn)品大量生產(chǎn)所依賴(lài)的一項(xiàng)重要工業(yè)與技術(shù)。模具制造的精密程度和技術(shù)層次,對(duì)于生產(chǎn)產(chǎn)品的品質(zhì),生產(chǎn)原料的有效利用,以及生產(chǎn)力的提高等方面,均有絕對(duì)性的影響。模具業(yè)為一切工業(yè)之母,而模具業(yè)又以塑料模為主。與我們生活息息相關(guān)的家電產(chǎn)品,電信產(chǎn)品及汽車(chē)零件中,大部分皆為塑料制品??萍嘉拿鞯倪M(jìn)步,人類(lèi)生活水平不斷提高在工業(yè)社會(huì)里各產(chǎn)品推陳出新。為達(dá)到此目的,必須以模具大量生產(chǎn),以達(dá)到尺寸穩(wěn)定,經(jīng)濟(jì)實(shí)用的目的。該設(shè)計(jì)的設(shè)計(jì)題目是蓋塞注塑模具設(shè)計(jì),由于該塑件的結(jié)構(gòu)特點(diǎn)和本質(zhì)特性,造成了它的生產(chǎn)類(lèi)型,該塑件的生產(chǎn)為大批量生產(chǎn)、PS(聚苯乙烯)塑料的成型性能特點(diǎn)以及蓋塞的結(jié)構(gòu)的特點(diǎn),設(shè)計(jì)成蓋塞注塑模具較為合理。由于蓋塞為日常通用零件,對(duì)其精度要求并不是很高。但由于其特殊的結(jié)構(gòu)原因,在成型的時(shí)候需要成型外部螺紋,使模具結(jié)構(gòu)變得相對(duì)復(fù)雜,從而增加了裝配時(shí)的難度。為成型螺紋,模具結(jié)構(gòu)上需要采用螺紋抽芯機(jī)構(gòu),為便于螺紋型芯的抽出,模具采用齒輪齒條抽芯機(jī)構(gòu),即可采用普通臥式注塑機(jī),由于塑件對(duì)精度要求不高,成型零件加工也相對(duì)容易。本模具采用一模兩腔,但總體上該模具機(jī)構(gòu)相對(duì)簡(jiǎn)單,制造容易,生產(chǎn)周期不是很長(zhǎng),從而節(jié)約了企業(yè)公司單位的加工成本,大大的縮短了模具制造周期。關(guān)鍵詞:外部螺紋;螺紋抽芯;齒輪齒條機(jī)構(gòu)AbstractMold is a product of modern industrial mass production depends is an important industrial and technology. Mold manufacturing and technical level of sophistication, for production of quality products, efficient use of raw materials, as well as increased productivity, etc., have absolute influence. Mold industry is the mother of all industries, while the plastic mold industry again dominated. With our lives, home appliances, telecommunication products and automobile parts, most are all plastic products. Technological advances of civilization, human beings living standards continue to improve in the industrial society of each product innovation. For this purpose, the mold must be produced in large quantities in order to achieve dimensional stability, economical and practical purposes.This design titled The closure injection mold design, due to the essential characteristics of the plastic lid stopper member, the stopper lid plastic parts production batch, PS (polystyrene) plastic molding performance characteristics and the structural characteristics of the cover plug, designed to cover the plug injection mold is more reasonable. And the cover plug for the common parts, its precision is not very high and other conditions. Also due to the structural characteristics of various reasons, we need external thread molding, the mold structure when the molding becomes relatively complicated and more difficult during assembly. The thread forming, need to adopt the structure of the mold core pulling thread, the thread core to facilitate the extraction of the mold core pulling rack and pinion mechanism, you can use ordinary horizontal injection molding machine, and the accuracy is not required for plastic parts, molded parts machining easier.The plastic mold using a two cavity mold, the mold body generally simple, easy to manufacture, short production cycle, saving companies the cost of processing and shorten the mold manufacturing cycle.Key words: External Thread; Thread Core Pulling; Rack And Pinion Mechanism目錄第1章 模具工藝規(guī)程的編制1 1.1塑件的工藝性分析1 1.1.1塑件的原材料分析1 1.2計(jì)算塑件的體積和質(zhì)量2 1.3塑件注塑工藝參數(shù)的確定3第2章注塑模的結(jié)構(gòu)設(shè)計(jì)4 2.1 選擇分型面選擇4 2.2 確定型腔的排列方式4 2.3設(shè)計(jì)澆注系統(tǒng)設(shè)計(jì)5 2.3.1主流道設(shè)計(jì)5 2.3.2分流道的設(shè)計(jì)5 2.3.3澆口的設(shè)計(jì)5 2.3.4排氣槽的設(shè)計(jì)6 2.4 成型零件的結(jié)構(gòu)設(shè)計(jì)6 2.4.1型腔的結(jié)構(gòu)設(shè)計(jì)6 2.4.2型芯的結(jié)構(gòu)設(shè)計(jì)6第3章 模具設(shè)計(jì)的有關(guān)計(jì)算7 3.1型腔和型芯工作尺寸的計(jì)算7 3.2螺紋型環(huán)徑向尺寸計(jì)算7 3.3 型腔底板厚度計(jì)算8 3.4 螺紋抽芯機(jī)構(gòu)設(shè)計(jì)9第4章模具加熱和冷卻系統(tǒng)的計(jì)算13 4.1 求塑件在硬化時(shí)每小時(shí)釋放的熱量Q113第5章模具閉合高度的確定14第6章注塑機(jī)有關(guān)參數(shù)的校核15第7章結(jié)構(gòu)與輔助零部件的設(shè)計(jì)16 7.1 導(dǎo)柱的選用16 7.2 導(dǎo)套的選用16第8章繪制模具總裝配圖和非標(biāo)零件工作圖18第9章模具的裝配與調(diào)試19 9.1 模具的裝配19 9.2試模199.3 試模可能產(chǎn)生的問(wèn)題及改善措施20 9.3.1 粘著模腔20 9.3.2 粘著模芯20 9.3.3 粘著主流道21 9.3.4 成型缺陷21 9.3.5 調(diào)整措施23結(jié)論24參考文獻(xiàn)25致謝26沈陽(yáng)化工大學(xué)科亞學(xué)院學(xué)士學(xué)位論文 第1章模具工藝規(guī)程的編制第1章 模具工藝規(guī)程的編制此次設(shè)計(jì)的塑件是一個(gè)簡(jiǎn)單的蓋塞,其零件圖如圖1所示。該塑件所用的材料采用PS(聚苯乙烯塑料),它的生產(chǎn)類(lèi)型為批量型生產(chǎn)。1.1塑件的工藝性分析1.1.1塑件的原材料分析塑件所采用的材料為PS(聚苯乙烯塑料),由于該塑件材料有諸多的特點(diǎn),所以用途較廣,而且耐用,從使用性能上看,它的電絕緣性(尤其是高頻絕緣性)比較不錯(cuò),呈無(wú)色透明的狀態(tài),而且著色性,耐水性,化學(xué)穩(wěn)定性的穩(wěn)定性都是非常不錯(cuò)的,其強(qiáng)度一般,但是它是屬于質(zhì)地比較脆若弱,容易產(chǎn)生碎裂,不耐苯,汽油等有機(jī)溶劑。從成型的能上看,它屬于無(wú)定型材料,而且吸濕性小,不容易分解,但是它受熱的時(shí)候變形較大所以熱脹系數(shù)大。并且很容易產(chǎn)生內(nèi)應(yīng)力。流動(dòng)性較好,可以采用螺桿式或柱塞式注射機(jī)成型。噴嘴用直通式或自鎖式,但必須注意的是應(yīng)考慮到防止飛邊,宜用高料溫,高模溫低注塑壓力,延長(zhǎng)注射時(shí)間可以有利于降低內(nèi)應(yīng)力,能夠有效的防止縮孔,變形??梢圆捎酶鞣N形式的澆口,澆口與塑件圓弧連接,以免去除澆口時(shí)損壞塑件。要求塑件脫模斜度大,頂出均勻,塑件壁厚要保持均勻,最好不帶嵌件,各面應(yīng)以圓弧連接,不允許有缺口,尖角。塑件壁厚均勻,不帶嵌件,不可以頂出機(jī)構(gòu),因此在成型時(shí)注意控制成型溫度,這個(gè)注塑塑件成型不是很難。1.1.2 塑件的結(jié)構(gòu)和尺寸精度及表面質(zhì)量分析 圖1 蓋塞零件圖 (1) 結(jié)構(gòu)分析從零件圖上分析,該塑件的總體形狀為圓柱形。在長(zhǎng)度方向上的一側(cè)有一段M28的螺紋,長(zhǎng)8。設(shè)計(jì)時(shí)需要采用螺紋抽芯機(jī)構(gòu)。在另一側(cè)的端面上有大小相同的均布的48的孔。該塑件的結(jié)構(gòu)形狀尺寸從整體結(jié)構(gòu)上來(lái)看較簡(jiǎn)單,因此,模具的設(shè)計(jì)內(nèi)容也不是特別難,設(shè)計(jì)起來(lái)比較容易,設(shè)計(jì)時(shí)為了成型螺紋必須設(shè)置齒輪,齒條抽芯機(jī)構(gòu),可以使得螺紋成型。這個(gè)注塑模具的設(shè)計(jì)的難易程度應(yīng)該屬于中等。 (2)尺寸精度分析該塑件的尺寸精度較簡(jiǎn)單,未注尺寸公差等級(jí),其公差等級(jí)取MT5。各尺寸精度要求的較低,其零件和模具的一些加工尺寸應(yīng)該留足余量。注塑塑件的壁厚,壁厚的最大尺寸為5,壁厚的最小尺寸為2.5,其差額為2.5,只要都在這個(gè)尺寸當(dāng)中,這個(gè)注塑塑件在成型的時(shí)候不是很難。 (3)表面質(zhì)量分析這個(gè)注塑塑件的外面不能有裂紋,內(nèi)部也不能有損傷,對(duì)表面的質(zhì)量不是很高。所以成型的時(shí)候不是很難。綜合上述分析可以看出,注塑時(shí)在工藝參數(shù)控制好的情況下,零件的成型要求可以得到保證。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)以及確定模具型腔數(shù)量。計(jì)算塑件的體積V V=V1+V2+V3 8731mm計(jì)算塑件的質(zhì)量,根據(jù)設(shè)計(jì)手冊(cè),可以查得PS塑料的密度為=1.05g/。故塑件的質(zhì)量M M=V =1.05108731g 9.06g此注塑模具采用一模兩腔的結(jié)構(gòu),由于外部的尺寸大小,和在澆注時(shí)需要的壓強(qiáng)和其他的條件等,暫定選用注塑機(jī)為XS-ZY-125型。1.3塑件注塑工藝參數(shù)的確定查找相關(guān)文獻(xiàn),對(duì)PS塑料的成型工藝參數(shù)作如下選擇(試模時(shí),根據(jù)實(shí)際情況作適當(dāng)?shù)恼{(diào)整):注塑溫度:包括料筒溫度和噴嘴的溫度。料筒溫度:后段溫度選用150;中段溫度選用160;后段溫度選用180; 噴嘴溫度:選用170; 模具溫度:選用45; 注塑壓力:選用80MPa; 注塑時(shí)間:選用40; 保壓壓力:選用55MPa; 保壓時(shí)間:選用25; 冷卻時(shí)間:選用40;成型周期:110。33沈陽(yáng)化工大學(xué)科亞學(xué)院學(xué)士學(xué)位論文 第2章注塑模的結(jié)構(gòu)設(shè)計(jì)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)也是設(shè)計(jì)當(dāng)中的重點(diǎn),那么結(jié)構(gòu)的設(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,冷卻水道的布局,澆口位置的設(shè)置,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、頂出機(jī)構(gòu)的設(shè)計(jì)等內(nèi)容。2.1 選擇分型面選擇分型面的選擇決定了模具的結(jié)構(gòu),選擇時(shí)應(yīng)根據(jù)分型面選用原則和塑件的成型要求來(lái)選擇分型面。該塑件為蓋塞,其表面質(zhì)量無(wú)特殊要求。塑件高度為23,除一端有M28的螺紋外,它的界面形狀圖是比較簡(jiǎn)單的,如果選擇端面為分型面,在脫模時(shí)不容易螺紋抽芯,抽芯困難。在進(jìn)行時(shí),盡量選擇簡(jiǎn)單的方式,如果選擇臺(tái)階處為分型面,脫模較容易,可以利用48的孔止轉(zhuǎn),減少了模具加工的難度,便于成型后取出塑件。故應(yīng)選用如下圖2所示的分型較為合理。 圖2 分型面2.2 確定型腔的排列方式這個(gè)注塑塑件在注塑的時(shí)候需要一模兩腔的樣式,就是所成型的模具要用兩個(gè)型腔。全面思考澆注系統(tǒng),模具結(jié)構(gòu)的復(fù)雜程度等因素,擬采用下圖3所示型腔排列方式。 圖3 型腔的排列方式采用上圖所示的型腔排列方式便于設(shè)計(jì)齒輪,齒條螺紋抽芯機(jī)構(gòu),其齒條布置在開(kāi)模方向上,結(jié)構(gòu)較簡(jiǎn)單,并且結(jié)構(gòu)較為緊湊。2.3設(shè)計(jì)澆注系統(tǒng)設(shè)2.3.1主流道設(shè)計(jì)取主流道的小端直徑=5.為了便于將凝料從主流道中拔出,將主流道設(shè)計(jì)成圓錐形,其錐度取13,該主流道錐度選取3。經(jīng)換算得到主流道大端直徑D=9。為了使熔料順利的進(jìn)入分流道,可以在主流道出料端設(shè)計(jì)半徑R=1的圓弧過(guò)渡。2.3.2分流道的設(shè)計(jì)分流道的形狀以及尺寸的設(shè)計(jì),根據(jù)塑件的體積,壁厚,形狀的復(fù)雜程度,注射速率,分流道長(zhǎng)度等因素來(lái)確定。2.3.3澆口的設(shè)計(jì)依照注塑塑件成型的條件和形腔排列的要求,我們應(yīng)該選擇側(cè)澆口。它的外形界面看起來(lái)比容易簡(jiǎn)潔,加工也比較方便。進(jìn)料時(shí)考慮從臺(tái)階處進(jìn)料,并且在模具結(jié)構(gòu)上可以利用分型面排氣。采用矩形截面的側(cè)澆口,在澆口的連接處型腔的部位應(yīng)成圓角,有利于料流。查表初選矩形截面尺寸為(BH)=1.151.00.9,在一開(kāi)始的時(shí)候應(yīng)該加以修改。2.3.4排氣槽的設(shè)計(jì)因?yàn)槟>叱叽巛^小擬采用分型面處排氣,即可滿(mǎn)足要求。2.4 成型零件的結(jié)構(gòu)設(shè)計(jì)2.4.1型腔的結(jié)構(gòu)設(shè)計(jì)該塑件的模具結(jié)構(gòu)采用一模兩腔的形式,考慮其結(jié)構(gòu)的加工難易程度和材料的合理利用等因素,凹模擬采用與定模固定板作成一體,可以節(jié)省材料也能滿(mǎn)足使用要求。其結(jié)構(gòu)形式如零件圖1所示,圖中的孔分別用來(lái)安裝齒條和導(dǎo)柱孔。根據(jù)分流道與澆口的設(shè)計(jì)要求,分流道,主流道均可開(kāi)設(shè)在定模固定板上,節(jié)省材料,也可以滿(mǎn)足使用要求。2.4.2型芯的結(jié)構(gòu)設(shè)計(jì)型芯主要是與型腔相結(jié)合構(gòu)成模具型腔,考慮其加工的難易程度,其型芯分為三個(gè)部分,一是成型螺紋部分的螺紋型環(huán)。二是成型端面圓孔的部分將其作成四個(gè)小型芯,便于加工。三是成型塑件內(nèi)部的形狀部分。其具體結(jié)構(gòu)形式如零件圖02.03.04所示。其中小型芯03與型芯04上的四個(gè)孔過(guò)盈配合。沈陽(yáng)化工大學(xué)科亞學(xué)院學(xué)士學(xué)位論文 第3章模具設(shè)計(jì)的有關(guān)計(jì)算第3章 模具設(shè)計(jì)的有關(guān)計(jì)算查手冊(cè)可知,PS塑料的收縮率為S=0.10.8,故其平均收縮率為 S=(0.1+0.8)/2=0.45??紤]生產(chǎn)實(shí)際,模具制造的公差選取=/3。3.1型腔和型芯工作尺寸的計(jì)算型腔,型芯工作尺寸計(jì)算如表1: 表1 型芯尺寸計(jì)算表類(lèi)別模具零件名稱(chēng)塑件尺寸計(jì)算公式工作尺寸型腔的尺寸型腔15Hm1=Hmax+HmaxSmid-C-0.5(T+T)14.6835D=Dmax +Dmax max-T34.84型芯的尺寸大型芯25d =d +d Smax +Tz25.2717Dm=Dmax+DmaxSmax-Tz16.89小型芯6Hm=Hmax+HmaxSmax-0.5(Tz+Tm)5.928Dm=dmin+dminSmin+Tz8.143.2螺紋型環(huán)徑向尺寸計(jì)算螺紋的基本尺寸為M28,為粗牙螺紋。查手冊(cè)可知,其螺距為3.5,中徑尺寸為27.727,小徑尺寸為26.21。中徑的制造公差中=0.03,大小徑的制造公差中=0.04。螺紋型環(huán)的中徑為 由公式 Dm中=Ds中+Ds中Scp-中 得 Dm中=27.727+27.7270.45-0.15 =27.7螺紋型環(huán)的外徑為 由公式 Dm外=Ds外+Ds外Scp-1.2中 Dm外=30+300.45-1.20.2 =27.73 螺紋型環(huán)的內(nèi)徑為: 由公式 Dm內(nèi)=Ds內(nèi)Scp-中 =26.211+26.2110.45-1.20.2 =26.133.3 型腔底板厚度計(jì)算在注塑成型過(guò)程中,型腔所受的力合膜時(shí)的壓力開(kāi)模式的拉力等。其中最主要的是塑料的熔體的壓力。在塑料熔體的壓力作用下,型腔將產(chǎn)生內(nèi)應(yīng)力及形變。對(duì)于該塑料,其強(qiáng)度不足是主要問(wèn)題型腔底板厚底應(yīng)按強(qiáng)度條件計(jì)算。 由強(qiáng)度計(jì)算公式 th= 得 th=/4 =21.4mm 式中th型腔底板的計(jì)算厚度(mm); Pm模腔的壓力(MPa); r材料許用應(yīng)力(MPa);(材料為45鋼,其許用應(yīng)力160MPa) 3.4 螺紋抽芯機(jī)構(gòu)設(shè)計(jì) 該塑件的一端有一段M28的外螺紋,脫模時(shí)阻礙成型后塑件從模具中脫出,其成型螺紋的軸線與快模方向一致,設(shè)計(jì)時(shí)需要在齒輪齒條傳動(dòng)后再用圓錐齒輪或其他方式換向。在其塑件結(jié)構(gòu)上要求塑件或模具的一側(cè)又回轉(zhuǎn)又軸向運(yùn)動(dòng),來(lái)實(shí)現(xiàn)塑件的自動(dòng)脫螺紋。該塑件模具設(shè)計(jì)擬采用動(dòng)模一側(cè)設(shè)置回轉(zhuǎn)運(yùn)動(dòng),利用端面上的48的孔可以防止塑件隨螺紋型環(huán)一起旋轉(zhuǎn)當(dāng)止動(dòng)部分長(zhǎng)度H和螺紋長(zhǎng)度相等時(shí),回轉(zhuǎn)終了即使沒(méi)有頂出機(jī)構(gòu)塑件也能落下。其齒輪齒條脫螺紋機(jī)構(gòu)如下圖4所示,其旋轉(zhuǎn)方向如圖。圖4 齒輪齒條脫螺紋機(jī)構(gòu)模具的開(kāi)模時(shí)所需的時(shí)間: t = s/v =270/40 s =6.75s由齒條直線運(yùn)動(dòng)的速度V與齒輪分度圓直徑,轉(zhuǎn)速之間的關(guān)系為 V=3.14dn/60 (mm/s) 選用與齒條嚙合的齒輪分度圓直徑為20,故 n=60V/3.14d 3.8r/s 選取脫螺紋的時(shí)間為3,則螺紋型環(huán)的轉(zhuǎn)速為 n5=r/s 故齒輪1與齒輪5之間的傳動(dòng)比i為 i = n1/n5 =3.8/1r/s =3.8r/s .則斜齒輪2的轉(zhuǎn)速為3.8r/s; 齒輪5的轉(zhuǎn)速為1r/s; 取斜齒輪2, 3之間的傳動(dòng)比為2; 則齒輪4,5之間的傳動(dòng)比為 i15=i5/i23 =3.8/2 =1.9 齒輪3的轉(zhuǎn)速為 n3=n2/i3 =3.8/2 r/s =1.9r/s 螺紋旋轉(zhuǎn)脫模力矩M,由公式 M=f cPSr2= f cP2r2 P2=1.5aE(Tf-Tj)(d2-d1) =1.5710 20.710 (90-60)(30 -26.211 ) =1811.4N M= f cP2r2 =0.451811.4(27.727/2) =11297.7N 式中a塑料的線膨脹系數(shù); E脫模溫度下,塑料的抗拉彈性模量(MPa); Tf軟化溫度; = T脫模頂出時(shí)制品的溫度; d螺紋外徑 d1螺紋內(nèi)徑; f c 脫模系數(shù); P2 制品外螺紋齒形對(duì)鋼型芯牙形的軸向包緊力(N); r2 螺紋中徑的半徑值;直齒輪分度圓直徑的計(jì)算:由公式 d2.32選用載荷系數(shù)K=1.3;齒寬系數(shù)=0.8;查得彈性影響系數(shù)ZE=189.8;其齒輪材料選用45鋼,查得接觸疲勞強(qiáng)度極限=470MP;對(duì)于減速傳動(dòng),其齒輪的齒數(shù)比等于傳動(dòng)比 =1.9選取齒輪5的齒數(shù)為30,則大齒輪齒數(shù) Z2=Z1 =301.9 =57 d 2.32 =36.3由公式 d1=d =36.3 =35查得式中載荷系數(shù)K=1.20;取模數(shù)為標(biāo)準(zhǔn)值m=1; 則分度圓直徑: d5=mZ5=301=30mm d4=mz4=571=57mm 齒輪的寬度: b=dd5 =300.8mm =24mm沈陽(yáng)化工大學(xué)科亞學(xué)院學(xué)士學(xué)位論文 第6章注塑機(jī)有關(guān)參數(shù)的校核第4章 模具加熱和冷卻系統(tǒng)的計(jì)算在注塑成型時(shí)模具溫度為45,其溫度低于80。因而模具在結(jié) 構(gòu)上不需要設(shè)置加熱系統(tǒng),是否需要冷卻系統(tǒng)做如下設(shè)計(jì)計(jì)算:模具的平均工作溫度為45,用20的常溫水作為冷卻介質(zhì),其 出口冷卻水溫度為25,其產(chǎn)量為(初算每三分鐘一套)0.36kg/h。4.1 求塑件在硬化時(shí)每小時(shí)釋放的熱量Q1查取相關(guān)的文獻(xiàn)資料得到PS塑料的單位熱流量為27.210 J/kg Q1=WQ2 =0.3627.210J =9.810J根據(jù)熱平衡條件 Qout=Qin可得 Mw=(im)/cw(tout- tin) Mw=v V=(im)/ cw(tout- tin)式中 mw 冷卻水每小時(shí)用量; cw 冷卻水的比熱容(4.187KJ/kg) tout 模具的出水口溫度; tin 模具冷卻水進(jìn)水溫度; V 冷卻水的體積; V= (0.3627.210)/604.18710(25-20) =7.810mm/min由體積流量V查表可知所需的冷卻水管的直徑很小。由上述計(jì)算可知,因?yàn)槟>呙糠昼娝璧睦鋮s水體積流量很小,故可不設(shè)定冷卻冷卻系統(tǒng),依靠空冷的方式冷卻模具即可。第5章 模具閉合高度的確定從零件圖上分析,該塑件的總體形狀為圓柱形。在長(zhǎng)度方向上的一側(cè)有一段M28的螺紋,長(zhǎng)8。設(shè)計(jì)時(shí)需要采用螺紋抽芯機(jī)構(gòu)。在另一側(cè)的端面上有大小相同的均布的48的孔。該塑件的結(jié)構(gòu)形狀尺寸從整體結(jié)構(gòu)上來(lái)看較簡(jiǎn)單,因此,模具的設(shè)計(jì)內(nèi)容也不是特別難,設(shè)計(jì)起來(lái)比較容易,設(shè)計(jì)時(shí)為了成型螺紋必須設(shè)置齒輪,齒條抽芯機(jī)構(gòu),可以使得螺紋成型。這個(gè)注塑模具的設(shè)計(jì)的難易程度應(yīng)該屬于中等。該塑件的尺寸精度較簡(jiǎn)單,未注尺寸公差等級(jí),其公差等級(jí)取MT5。各尺寸精度要求的較低,其零件和模具的一些加工尺寸應(yīng)該留足余量。注塑塑件的壁厚,壁厚的最大尺寸為5,壁厚的最小尺寸為2.5,其差額為2.5,只要都在這個(gè)尺寸當(dāng)中,這個(gè)注塑塑件在成型的時(shí)候不是很難。制品為外螺紋件,該模具設(shè)計(jì)一模兩腔,采用齒輪齒條旋螺紋機(jī)構(gòu)脫出制品,工作原理為:開(kāi)模時(shí),由于螺紋型芯16和型芯15的作用,制品留在動(dòng)模,同時(shí)定模齒條13帶動(dòng)直齒輪6,通過(guò)錐齒輪4和8傳動(dòng)螺紋型芯16,型芯15上有四個(gè)小型芯令制品止轉(zhuǎn),隨著開(kāi)模距離增大螺紋型芯旋轉(zhuǎn)幾周后,制品連同流到凝料一起脫落。利用塑料的擠壓性和可摸塑性,將松散的料粒或粉狀成型物料從注射劑的料斗送入高溫機(jī)筒內(nèi)加熱熔融塑化,使之成為粘流態(tài)熔體,在柱塞或螺桿的高壓推動(dòng)下,開(kāi)啟模具便可從模腔中脫出具有一定形狀和尺寸的塑料制件在支承與固定零件中,其尺寸設(shè)計(jì)根據(jù)經(jīng)驗(yàn)確定:取定模固定板(型腔板)的厚度40。固定板厚度取30,墊板的厚度取50;支承板厚度取20,支架的高度取60;因而模具的閉合高度 H=H1+H2+H3+H4+H5 =40+30+50+20+60 =200第6章 注塑機(jī)有關(guān)參數(shù)的校核該模具的外形尺寸為350200200,選用的XS-ZY-125型注塑機(jī)模最大安裝尺寸370320。故該注塑機(jī)能夠滿(mǎn)足模具的安裝要求。由上述計(jì)算可知模具的閉合高度H=200。XS-ZY-125型注塑機(jī)所允許的最小模具厚度Hmin=150mm,最大模具閉合高度Hmax=300mm。模具的安裝條件: HminHHmax 150mm200mm300mm即滿(mǎn)足模具的安裝條件。查資料可知,XS-ZY-125型注塑機(jī)的最大開(kāi)模行程S=270,模具頂出塑件要求開(kāi)模行程 S=H1+H2+(510) =15+8+10 =33注塑機(jī)的開(kāi)模行程能夠滿(mǎn)足頂出塑件的要求。由于螺紋的抽芯距離較短,不會(huì)過(guò)大的增加開(kāi)模行程,注塑機(jī)的開(kāi)模行程足夠。經(jīng)過(guò)驗(yàn)證,XS-ZY-125型注塑機(jī)能夠滿(mǎn)足使用要求,可以采用。沈陽(yáng)化工大學(xué)科亞學(xué)院學(xué)士學(xué)位論文 第7章結(jié)構(gòu)與輔助零部件的設(shè)計(jì)第7章 結(jié)構(gòu)與輔助零部件的設(shè)計(jì)7.1 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5所示: 圖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(12)。7.2 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6所示: 圖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。在設(shè)計(jì)制造澆注的過(guò)程當(dāng)中,其要求對(duì)此注塑塑件的精度不是很高,我們只需要兩根導(dǎo)柱就能控制此塑件的精度,選取兩根導(dǎo)柱,保持導(dǎo)套的直徑相同,采取不對(duì)稱(chēng)布置。布置方式在零件圖的固定模版上顯示。沈陽(yáng)化工大學(xué)科亞學(xué)院學(xué)士學(xué)位論文 第8章繪制模具總裝配圖和非標(biāo)零件工作圖第8章 繪制模具總裝配圖和非標(biāo)零件工作圖該蓋塞注塑模具總裝配圖,非標(biāo)零件圖已經(jīng)在附圖中顯示。蓋塞注塑模具的工作原理:開(kāi)模時(shí),塑件被帶到動(dòng)模上的同時(shí),定板在定模上的齒條,與在動(dòng)模上的齒輪的作用下,使螺紋型環(huán)16沿著塑件脫出方向旋轉(zhuǎn),至塑件完全脫出螺紋型環(huán)16為止。制品為外螺紋件,該模具設(shè)計(jì)一模兩腔,采用齒輪齒條旋螺紋機(jī)構(gòu)脫出制品,工作原理為:開(kāi)模時(shí),由于螺紋型芯16和型芯15的作用,制品留在動(dòng)模,同時(shí)定模齒條13帶動(dòng)直齒輪6,通過(guò)錐齒輪4和8傳動(dòng)螺紋型芯16,型芯15上有四個(gè)小型芯令制品止轉(zhuǎn),隨著開(kāi)模距離增大螺紋型芯旋轉(zhuǎn)幾周后,制品連同流到凝料一起脫落。利用塑料的擠壓性和可摸塑性,將松散的料?;蚍蹱畛尚臀锪蠌淖⑸鋭┑牧隙匪腿敫邷貦C(jī)筒內(nèi)加熱熔融塑化,使之成為粘流態(tài)熔體,在柱塞或螺桿的高壓推動(dòng)下,以很大的流速通過(guò)機(jī)筒前端的噴嘴注射進(jìn)入溫度較低的閉合模具中,經(jīng)過(guò)一段保壓冷卻定時(shí)間型后,開(kāi)啟模具便可從模腔中脫出具有一定形狀和尺寸的塑料制件。注射機(jī)原理如圖7所示:圖7注射原理沈陽(yáng)化工大學(xué)科亞學(xué)院學(xué)士學(xué)位論文 第9章模具的裝配與調(diào)試第9章 模具的裝配與調(diào)試9.1 模具的裝配由于型芯,型腔在合模后很難找正相對(duì)位置,故應(yīng)先安裝齒輪,齒條作為安裝基準(zhǔn)。裝配過(guò)程如下: (1) 裝配前按照零件圖檢驗(yàn)其工作零件的尺寸及其他零件是否齊備; (2) 將型芯1裝配到型芯15上,保證軸線與端面的垂直度; (3) 將導(dǎo)套壓入到定模固定板2中,并保證其軸線與端面的垂直度; (4) 將齒條13壓入到定模固定板2中,保證其垂直度; (5) 將圓套7壓入到支架14中; (6) 將齒輪軸6穿過(guò)支架上的圓套7后,安放在齒條13上,找正位置,將其放上支座25。在其銷(xiāo)釘孔打入銷(xiāo)釘,擰緊螺釘; (7) 將圓錐齒輪4裝在齒輪軸6的端面上,并用鍵5固定; (8) 將導(dǎo)柱打入固定板19中,保證軸線與端面的垂直度; (9) 型芯15套入螺紋型環(huán)16中后,放入固定板19中定位; (10) 將圓錐齒輪套入固定軸9中,將固定軸定位于固定板19中; (11) 在固定板6與支撐板10之間加上墊板20,調(diào)整圓錐齒輪和螺紋型環(huán),使其正確嚙合后,將其用螺母固定。在固定板19與支撐板10以及墊板上投窩打孔,擰緊螺釘; (12) 最后,將支架14與固定板用螺釘固定; (13) 裝配完成,試模。9.2試模 (1)試模前,要先對(duì)設(shè)備進(jìn)行檢查,和對(duì)各種參數(shù),是否正常運(yùn)轉(zhuǎn),如果出現(xiàn)問(wèn)題并在試模的時(shí)候提前解決; (2)采用合適的原料,并檢查是否存在質(zhì)量的問(wèn)題,并且制定適當(dāng)?shù)墓に噮?shù);(3)在開(kāi)始試模時(shí)要規(guī)定壓力,溫度,時(shí)間并按要求的參數(shù)進(jìn)行加工澆注;(4)這樣的先后順序變動(dòng),注意一次只改變一個(gè)參數(shù); (5)在試模過(guò)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(jiàn); (6)通過(guò)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(kù)。9.3 試模可能產(chǎn)生的問(wèn)題及改善措施在試模時(shí)產(chǎn)生的樣品制件代表著所有的模具的材質(zhì)和參數(shù)。用這樣的方式來(lái)檢驗(yàn)和記錄數(shù)據(jù)。然而,在一開(kāi)始實(shí)驗(yàn)時(shí)我們并不能得到完整的數(shù)據(jù)和樣件,這需要經(jīng)過(guò)大量的數(shù)據(jù)統(tǒng)計(jì)和實(shí)驗(yàn)。由于塑件的粘性這個(gè)一特性,會(huì)造成很大的誤差數(shù)據(jù)。這也是在開(kāi)始之前首先解決的問(wèn)題。9.3.1粘著模腔制品粘著在模腔上,是指塑件在模具開(kāi)啟后,與設(shè)計(jì)意圖相反,離開(kāi)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(wú)法取出的一種反常現(xiàn)象。其主要原因是: (1)注射壓力過(guò)高,或者注射保壓壓力過(guò)高。 (2)注射保壓和注射高壓時(shí)間過(guò)長(zhǎng),造成過(guò)量充模。 (3)冷卻時(shí)間過(guò)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)部會(huì)有不同層次的凹槽,也有可能在脫模的時(shí)候受到了沖擊壓力,會(huì)大大的增加脫模的阻力。9.3.2 粘著模芯 (1)當(dāng)注射時(shí)候用較大的擠壓力和所持續(xù)的時(shí)間過(guò)長(zhǎng)是都會(huì)引起過(guò)量。 (2)當(dāng)冷凝時(shí)間較長(zhǎng)時(shí)其收縮量會(huì)相應(yīng)的增加。 (3)腔內(nèi)壁的溫度過(guò)高時(shí),也不能充分的固化。 (4)當(dāng)機(jī)筒的溫度和噴嘴的溫度都過(guò)高時(shí),也不能很好的使塑件達(dá)到固化效果。 (5)可能會(huì)有不利于脫模的凹槽和痕跡,都需要進(jìn)行優(yōu)化處理。9.3.3 粘著主流道 (1)在閉摸的時(shí)候要注意時(shí)間的間隔問(wèn)題,否則會(huì)出現(xiàn)不能被充分吸收的問(wèn)題。 (2)料道的徑向直徑要比塑件制品的壁厚大的多,冷凝的時(shí)間內(nèi)不能很路快的完成制品的固化。 (3)主流道的溫度需要得到有效的控制,否則無(wú)法完成很好的固化。 (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)當(dāng)主流導(dǎo)拉料桿不工作的時(shí)候。如果有了這幾個(gè)現(xiàn)象,先停止工作,在通過(guò)各種方式取出芯,不能讓其收到其他操作不當(dāng)引起的損傷,還要避免注塑模具的成型部位不能受到損傷。詳細(xì)的查找一些粘膜的原因,一邊對(duì)工藝做出調(diào)整和修改;還有在現(xiàn)場(chǎng)進(jìn)行師弟考察,做出數(shù)據(jù)統(tǒng)計(jì),一直達(dá)到所要求的標(biāo)準(zhǔn),在進(jìn)行第二次注射工藝。9.3.4 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(lái)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(jiàn)的成型制品主要缺陷及其改進(jìn)的措施進(jìn)行分析。 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(mǎn)型腔而得不到完整的制件。這種情況應(yīng)該算是司空見(jiàn)慣了。主要是因?yàn)椋?1) 熔料流動(dòng)阻力過(guò)大下面是主要原因:主流道的尺寸和分流道的尺寸設(shè)計(jì)的不匹配。流道內(nèi)部的結(jié)構(gòu)和材質(zhì)因?yàn)檫x取和設(shè)計(jì)的緣故,在熔料進(jìn)入后不能夠流通,不適合流動(dòng)。所以我們要選取合適的易于熔料流動(dòng)的材質(zhì)和設(shè)計(jì)結(jié)構(gòu),像圓形的流道。還有在熔料流動(dòng)過(guò)程當(dāng)中會(huì)有一部分可能出現(xiàn)了冷凝的狀態(tài),壁厚較薄時(shí)也會(huì)出現(xiàn)阻力過(guò)大的狀況。(2) 型腔排氣不良這個(gè)情況很常見(jiàn),但是很容易被操作者遺忘,但確實(shí)是非常重要的一個(gè)問(wèn)題。當(dāng)在要求的精度越高時(shí),這個(gè)顯現(xiàn)就越發(fā)的明顯了。重點(diǎn)在拐角處,凹槽處,所以要盡量的避免這些第低級(jí)誤差,結(jié)果會(huì)變的很麻煩,附帶的問(wèn)題會(huì)更多,處理起來(lái)也不好處理,最后的結(jié)果就是廢料,浪費(fèi)成本,消耗時(shí)間。(3) 鎖模力不足在注射的時(shí)候,由于工作原理的緣故,會(huì)造成動(dòng)摸的位置發(fā)生偏差動(dòng)模位置發(fā)生偏差,會(huì)造成熔料的偏移,而實(shí)際的位置可能會(huì)出現(xiàn)供料不足的情況,造成的結(jié)果就是會(huì)出現(xiàn)缺陷的現(xiàn)象,所以在操作的時(shí)候應(yīng)該避免這種為題的發(fā)生。 溢邊(毛刺、飛邊、批鋒)還有其他的原因,在熔料充滿(mǎn)腔的時(shí)候仍然出現(xiàn)諸多的毛刺,更有甚者毛刺更大,還有在縫隙出也會(huì)出現(xiàn)毛刺,產(chǎn)生這種顯現(xiàn)的原因有以下幾個(gè)方面:(1) 再注射的時(shí)候用量過(guò)多(2) 鎖模力不足(3) 流動(dòng)性暢通(4) 模具的部分不匹配(5) 模版出現(xiàn)形變 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:(1) 尺寸變大當(dāng)尺寸變大了的時(shí)候,其對(duì)應(yīng)的注射壓力也伴隨著升高,于是保壓的時(shí)間間隔也加長(zhǎng),在這種狀態(tài)下會(huì)有大量的充模,收縮率變?cè)絹?lái)越小,其值也變小,讓制造的工件的實(shí)際尺寸稍微偏大;當(dāng)模具溫度較低了的時(shí)候,而實(shí)際上使得熔料在較低溫度的條件下更容易成型,收縮率同樣的變得越來(lái)越小,并趨于最小值。此時(shí)還要繼續(xù)注射,并且盡快的提高模具的溫度和降低注射壓力,縮短保壓時(shí)間,制作工件尺寸可得到大大的改善。(2) 尺寸變小當(dāng)尺寸變小的時(shí)候,注射的壓力就會(huì)降低低、保壓時(shí)間就會(huì)變短,可能會(huì)造成不足的狀況,制作工件在冷卻后的時(shí)候它的收縮率會(huì)稍微的跟跟著改變,并有變大的趨勢(shì),使得制作工件的尺寸減小;當(dāng)模具溫度較高的時(shí)候,這時(shí)候的工件應(yīng)該從模腔取出來(lái),這時(shí)發(fā)生的變化時(shí)是它的體積收縮量變大,其尺寸大小卻變小。這時(shí)應(yīng)該重新定制加工工藝,并做出合理相應(yīng)的改變。通過(guò)改變加工工藝的條件和狀態(tài),通常只能在極小范圍內(nèi)使尺寸發(fā)生變化,這時(shí)候能改變工件的相互配合的大小的狀態(tài),但是公稱(chēng)尺寸一般來(lái)說(shuō)不會(huì)有大的變化。9.3.5 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。沈陽(yáng)化工大學(xué)科亞學(xué)院學(xué)士學(xué)位論文 結(jié)論結(jié)論畢業(yè)設(shè)計(jì)是本科教學(xué)工作的最后環(huán)節(jié),也是一個(gè)重要環(huán)節(jié),是對(duì)學(xué)生全面的知識(shí)的測(cè)試。通過(guò)這個(gè)設(shè)計(jì),將大學(xué)四年的學(xué)習(xí)進(jìn)一步的鞏固,由于該塑件的結(jié)構(gòu)特點(diǎn)和本質(zhì)特性,造成了它的生產(chǎn)類(lèi)型,該塑件的生產(chǎn)為大批量生產(chǎn)、PS(聚苯乙烯)塑料的成型性能特點(diǎn)以及蓋塞的結(jié)構(gòu)的特點(diǎn),設(shè)計(jì)成蓋塞注塑模具較為合理。由于蓋塞為日常通用零件,對(duì)其精度要求并不是很高。蓋塞為生活中常用零件,大批量生產(chǎn),便于加工生產(chǎn)。因?yàn)樵摿慵O(shè)計(jì)的注塑模選取了螺紋抽芯機(jī)構(gòu)。其中螺紋的成型較復(fù)雜。該模具采用一模兩腔,提高了生產(chǎn)效率,由于制件尺寸較小,采用空冷及能滿(mǎn)足冷卻要求,故此模具未開(kāi)設(shè)流道。通過(guò)計(jì)算該模具能夠滿(mǎn)足零件的生產(chǎn)要求,結(jié)構(gòu)較為合理,由于本人能力所學(xué)知識(shí)有限,定有許多不足之處,望老師批評(píng)指正。沈陽(yáng)化工大學(xué)科亞學(xué)院學(xué)士學(xué)位論文 參考文獻(xiàn)參考文獻(xiàn)1 楊安主編.塑料成型工藝與模具設(shè)計(jì)M.北京理工大學(xué)出版社,2007,8. 2 史鐵梁主編.模具設(shè)計(jì)指導(dǎo)M.機(jī)械工業(yè)出版社,2003,8.3 丁德全主編.金屬工藝學(xué)M.機(jī)械工業(yè)出版社,2000,5. 4 陳于萍,周兆元主編.互換性與測(cè)量技術(shù)基礎(chǔ)M.機(jī)械工業(yè)出版社,2005,10. 5 孫鳳勤主編.模具制造工藝與設(shè)備M.機(jī)械工業(yè)出版社,1999.6 彭建聲主編.模具技術(shù)問(wèn)答M.機(jī)械工業(yè)出版社,2000. 7 劉小年,陳婷主編.機(jī)械制圖M.機(jī)械工業(yè)出版社,2005,8. 8 黃毅宏主編.模具制造工藝學(xué)M.機(jī)械工業(yè)出版社,1996. 9 李富根主編.AutoCAD2007基礎(chǔ)M.北京希望電子出版社,2003.10模具實(shí)用技術(shù)叢書(shū)編委員.塑料模具設(shè)計(jì)制造與應(yīng)用實(shí)例M.機(jī)械工業(yè)出版社.2004,1.11 卜建新主編.塑料模具設(shè)計(jì)M.中國(guó)輕工業(yè)出版社.12 申樹(shù)義,高濟(jì)編.塑料模具設(shè)計(jì)M.機(jī)械工業(yè)出版社.13 塑料模具技術(shù)手冊(cè)編委會(huì).塑料模具設(shè)計(jì)手冊(cè)M.編機(jī)械工業(yè)出版社.14 葉久新,王群主編.塑料制品成型及模具設(shè)計(jì)M.湖南科學(xué)技術(shù)出版,2008,1.15 李大鑫,張秀棉.模具技術(shù)現(xiàn)狀與發(fā)展趨勢(shì)綜述J.模具制造,2005,2.16 趙昌盛,朱邦全.我國(guó)模具材料的應(yīng)用發(fā)展J.模具制造,2004,11.17 趙蓓蓓.初探塑料模具材料現(xiàn)狀及發(fā)展方向J.科技資訊,2009.18 伍先明,王群.塑料模具設(shè)計(jì)指導(dǎo)M.北京:國(guó)防工業(yè)出版社,2006.19 朱光力,萬(wàn)金保.塑料模具設(shè)計(jì)M.北京:清華大學(xué)出版社,200320 唐志玉主編.注塑模具設(shè)計(jì)師指南M.北京:國(guó)防工業(yè)出版社,1996.沈陽(yáng)化工大學(xué)科亞學(xué)院學(xué)士學(xué)位論文 致謝致謝隨著畢業(yè)將至,心里面不禁有了不舍和依戀,從大一到大四學(xué)校給了我很多改變和成長(zhǎng),畢業(yè)設(shè)計(jì)也隨之步入了尾聲,經(jīng)過(guò)小半年的學(xué)習(xí)研究過(guò)程,在陳慧珍老師以及同學(xué)的輔導(dǎo)和幫助下,完成了這篇畢業(yè)設(shè)計(jì)。首先要感謝陳慧珍老師,從選題、中期檢查、制圖到最后完成,每一步都是在陳老師的悉心指導(dǎo)下進(jìn)行的,我也知道這次的畢業(yè)論文讓老師付出了好多的日日夜夜,在此我向陳老師表示由衷的感謝。在寫(xiě)論文的過(guò)程中遇到過(guò)很多很多麻煩和問(wèn)題,每次遇到的問(wèn)題和盲點(diǎn),都是陳老師認(rèn)真細(xì)心的解答和修改,陳老師您辛苦了!這次的畢業(yè)設(shè)計(jì)也是對(duì)我大學(xué)四年專(zhuān)業(yè)知識(shí)的一次實(shí)際檢驗(yàn)和鞏固,畢業(yè)設(shè)計(jì)收獲了很多,即提高了自己的繪圖能力而且自我主動(dòng)學(xué)習(xí)的積極性更高了,但同時(shí)也暴露出很多的問(wèn)題,如專(zhuān)業(yè)基礎(chǔ)的不足,缺乏對(duì)相關(guān)知識(shí)不了解等。但是求學(xué)的道路還有很長(zhǎng),相信這次的畢業(yè)設(shè)計(jì)會(huì)成為我未來(lái)求學(xué)之路的動(dòng)力。在此,也要感謝學(xué)校這四年來(lái)給了我這么好的學(xué)習(xí)環(huán)境,感謝我的輔導(dǎo)員衣方丹老師,感謝給我上過(guò)課的優(yōu)秀老師,豐富的大學(xué)生活,這都會(huì)是我一生難忘的經(jīng)歷。最后,再次對(duì)所有老師和同學(xué)們表示由衷的感謝!因?yàn)槲业乃接邢?,設(shè)計(jì)的很難避免會(huì)有錯(cuò)誤,懇請(qǐng)獲得每個(gè)老師批評(píng)和糾正! 第38頁(yè) 共25頁(yè)Injection Molding GuideINTRODUCTIONObjectiveThis document provides guidelines for part design, mold design and processing of styrenic block copolymer (SBC) TPEs. The GLS product families that include styrenic TPEs are Kraton compounds, Dynaflex TPE compounds and Versaflex TPE alloys.SBC RheologyOne major characteristic of SBCs is that they are shearing dependent. A material is shear dependent when its viscosity is higher at low shear rates (such as extrusion) and lower at high shear rates (as in injection molding). Therefore, SBC compounds will flow more easily into thin areas of the mold at high shear rates. The shear thinning behavior of SBCs should be considered when designing injection molds and also when setting mold conditions during processing.Figure 1.The effect of shear rate on the viscosity of GLSstyrenic TPE compounds (measured at 390F (200C).To obtain information regarding the viscosity of an individual grade, refer to the Product Technical Data Sheet, available at www.glscorporation.com or contact your GLS representative.PART DESIGNGeneral Part Design ConceptsWhen designing a TPE part, there are a few general rules to follow: The part wall thickness should be as uniform as possible. Transitions from thick to thin areas should be gradual to prevent flow problems, back fills, and gas traps. Thick sections should be cored out to minimize shrinkage and reduce part weight (and cycle time). Radius / fillet all sharp corners to promote flow and minimize no-fill areas. Deep unventable blind pockets or ribs should be avoided. Avoid thin walls that cannot be blown off the cores by air-assist ejection. Long draws with minimum draft may affect ease of ejection.Flow Length and Wall ThicknessThe maximum achievable flow length is dependent on the specific material selected, the thickness of the part, and processing conditions. Generally, GLS compounds will flow much further in thinner walls than other types of TPEs. The flow to thickness ratio should be 200 maximum; however this is dependent on the material and the part design. High flow GLS TPE compounds (such as Versalloy) have been used successfully to fill flow ratios up to 400.The measurement of spiral flow offers a comparative analysis of a materials ability to fill a part. The spiral flow test is performed by injecting a material into a spiral mold (similar to a ribbon formed into a spiral). The distance the material flows is measured in inches. In this case, the spiral flow test was conducted using two different injection speeds (3 in/sec and 5 in/sec). The typical spiral flow lengths for the various GLS product families are summarized in Table 1. With specific compounds, flow lengths of up to 40 inches (at 5 in/sec injection speed) are possible.Table 1. Typical Spiral Flow Lengths for GLS Compounds*SeriesFlow length, in3 in/sec5 in/secDynaflex D13-1518-20Dynaflex G12-2218-30Versaflex 9-1613-26*Spiral flow tests performed using 0.0625 in thickness and 0.375 in width channel at 400F.For spiral flow information about a specific grade or additional details about the spiral flow test procedure, please refer to the GLS Corporation TPE Tips Sheet #7, available at www.glscorporation.com or by contacting your GLS representative.UndercutsThe flexibility and elastic nature of TPEs allows for the incorporation of undercuts into the part design. Because of their excellent recovery characteristics, GLS compounds are capable of being stretched and deformed, allowing them to be pulled from deep undercuts (Figure 2). If both internal and external undercuts are present on the same part, slides or core splits may be necessary. Parts with internal undercuts (e.g. bulb shaped parts) may be air ejected from the core by use of a poppet valve in the core. Minor permanent elongation (3% - 8%) due to deformation may occur during ejection.Figure 2. An example of TPE parts with large undercuts.Gate and Knit Line LocationsThe product engineer should indicate the areas of the part that are cosmetic and those that are functional and include this information on the drawing. This will help the mold designer to determine the allowable gate and knit line locations.AnisotropyThermoplastic materials that have different properties in the flow direction versus the cross-flow direction (90 perpendicular to the flow direction) are characterized as “anisotropic” materials. Properties that may be affected are shrinkage and tensile properties. Anisotropy is caused when the polymer chains orient in the direction of flow, which leads to higher physical properties in the flow direction. Wall thickness, injection speed, melt temperature and mold temperature are a few variables that affect anisotropy. Depending on the processing conditions and mold design, most GLS styrenic TPE compounds exhibit a degree of anisotropy.ShrinkageDue to their anisotropic nature, GLS styrenic TPE compounds shrink more in the flow direction than in the cross-flow direction. Generally, SEBS compounds have higher shrinkage and are more anisotropic than SBS compounds. Typical shrinkage values for SEBS-based compounds are 1.3% - 2.5%, whereas those for SBS based compounds are 0.3% - 0.5 %. Softer SEBS compounds (below 30 Shore A) will shrink more than harder 6 materials. Some grades, such as Dynaflex G7700, G7800, and G7900 Series contain filler, which reduces their shrinkage.The shrinkage values reported by GLS are determined using a 0.125” thick plaque. It should be noted that shrinkage is not an exact number, but a range value. This range can be affected by the part wall thickness, melt temperature, mold temperature, injection speed, hold/pack pressures and also the time between molding and measuring. As a result, prototyping is strongly recommended for parts with close tolerances to better quantify the realistic shrinkage of a specific grade of material in a specific application.For shrinkage values for specific grades, please refer to the product Technical Data Sheet, available at www.glscorporation.com or by contacting your GLS representative.MOLD DESIGNTypes of MoldsGLS SBC compounds can be molded in two- and three-plate molds. Both conventional and hot runner tool designs have been used with GLS compounds. Self-insulating hot runner tool designs are not recommended due to the potential for material degradation in the stagnation zones. Two-shot molds and insert molds can also be used. If a family mold is required, the cavity volumes should be similar, otherwise over packing and flashing of the smaller cavity may occur.Steel SelectionGLS styrenic TPEs are generally non-abrasive and non-corrosive. The selection of tool steel will depend on the quantity and quality of parts to be produced. For high volume production, the initial expense of quality tooling is a sound investment.A wide variety of tool steels are available for injection mold construction. Table 2 lists the properties of common tool steels and the typical mold components for which they are used. Soft metals, such as aluminum and beryllium copper, can be used for prototype parts or short production runs up to 10,000 parts.Table 2. Typical Tool Steel for Injection Mold ConstructionSteel TypeSteel PropertiesMold ComponentP-20Pre-hardened, machines well, high carbon, general-purpose steel. Disadvantage: May rust if improperly stored.Mold bases, ejector plates, and some cavities (if nickel or chrome plated to prevent rust).H-13Good general purpose tool steel. Can be polished or heat-treated. Better corrosion resistance.Cavity plates and core plates.S-7Good high hardness, improved toughness, general-purpose tool steel. Machines well, shock resistant, polishes well. Disadvantage: Higher cost.Cavity plates, core plates and laminates, as well as thin wall sections.A-2Good high toughness tool steel. Heat-treats and polishes well.Ejector pins, ejector sleeves, and ejector blades.D-2Very hard, high wear characteristics, high vanadium content, somewhat brittle. Disadvantage: Difficult to machine.Gate blocks, gibe plates to prevent galling, gate blocks to prevent wear.420 SSTough corrosion resistant material.Heat-treats and polishes well.Disadvantage: High cost.Cavity blocks, ejector pins, sleeves, etc.Some part designs may benefit from the use of higher thermal conductivity materials such as beryllium copper. This material is less durable than steel and may hob or wear faster than steel if used at the parting-line. Beryllium copper can be used for inserts, slides or cores to increase heat transfer rates and reduce cycle times. In cases where there is a long draw core, a fountain-type bubbler may be beneficial.Mold Surface Treatment, Finishing and TexturingMost GLS materials replicate the mold surface fairly well. To produce a glossy surface, a polished mold is required and an unfilled grade should be used. A highly polished tool and a transparent material are required to produce a part with good clarity. If a matte finish similar to that of a thermoset rubber is required, a rougher mold texture should be used (or a GLS product such as GLS Versalloy TPV alloys, which naturally produce a matte surface). In general, an EDM surface will produce a good texture and may improve release from the tool during part ejection. Matte surfaces can also help to hide any flow marks or other surface defects. Vapor honing, sand or bead blasting and chemical etching are also used to produce textured surfaces with varying degrees of gloss and appearance. To aid in release, the cavity or core may be coated with a release coating such as PTFE impregnated nickel after it has been given a sandblast or EDM finish.Sprue and Sprue Puller DesignThe sprue should have sufficient draft, from 1 to 3 to minimize drag and sprue sticking. Longer sprues may require more taper (3 - 5), as shown in Figure 3. Typically, the sprue diameter should be slightly larger than the nozzle diameter. An EDM finish is acceptable for most styrenic TPE materials. Permanent surface lubricant treatments have also been used successfully.Sprue puller designs vary with the hardness of the material. The different sprue designs possible and their relative dimensions are shown in Figures 4 through 7. In addition, Table 3 shows the typical hardness range for which a particular sprue design is applicable.Table 3. Typical Sprue Designs for Various Hardness ValuesTypical TPE Hardness RangeMost Common Sprue Puller TypesFigure50 Shore ATapered, Pin, Z-Type3, 4 and 640-70 Shore AUndercut55-40 Shore APine Tree7Hot sprue bushings and extended nozzles may also be used with GLS compounds. In many molds, the sprue is the thickest wall section in the mold and will control the minimum cooling time. The use of a hot sprue, which may be viewed as an extension of the machine nozzle, can sometimes reduce cycle time. Extended machine nozzles may also be used to reduce sprue length and size. When hot sprues are used, the machine nozzle tip should be a free-flow nozzle rather than a reverse tip.Figure 3. Tapered Sprue Puller Figure 4. Z-Pin Sprue PullerFigure 5. Undercut Sprue PullerFigure 6. Sucker Pin Sprue Puller Figure 7. Pine Tree Sprue PullerConventional Runner Configuration and DesignA balanced runner configuration is critical to achieve uniform part quality from cavity to cavity. In a balanced runner system, the melt flows into each cavity at equal times and pressure. The runner balance can be designed by using computer mold-flow analysis programs and verified by performing short-shot studies.An unbalanced runner may result in inconsistent part weights and dimensional variability. The cavity closest to the sprue may be over packed and flashing may occur. As a result of over packing, parts may also develop high molded-in stresses, which lead to warpage. Examples of balanced runner systems are shown in Figures 8 and 9.Figure 8. Example of Balanced Spider Runner Figure 9. Example of Balanced Cross-RunnerFigure 10 shows different runner cross-sections and their associated efficiency. Full round runners have the least resistance to flow and surface area, allowing the material to stay molten longer. The second most efficient runner cross-section is the modified trapezoid. This runner geometry most closely simulates a full round runner but only requires machining in only one plate. Figure 11 shows typical ball cutter dimensions and the corresponding modified trapezoid runner sizes. Figure 12 illustrates typical runner dimensions.Figure 10. Typical Runner Cross-SectionsFigure 11. Modified Trapezoid Runner SizesFigure 12. Runner Design and DimensionsCold slug wells should be used at each runner transition (turn). Cold slug wells serve to remove the leading edge of the melt. The slug well associated with the sprue should be large enough to trap the cold material formed in the machine nozzle during the mold-open cycle. Typical slug well dimensions are approximately 1.5 to 2.0 times the diameter or width of the feed runner.Runner KeepersRunner keepers or sucker pins provide undercuts to keep the runner on the desired plate but should not restrict material flow through the runner. Figures 8 and 9 show typical locations for runner keepers and sucker pins. Figure 13 illustrates an example design of a runner keeper.Figure 13. Runner Keeper designGate Design and LocationMost conventional gating types are suitable for processing GLS styrenic TPE compounds.The type of gate and the location, relative to the part, may affect the following: Part packing Gate removal or vestige Part cosmetic appearance Part dimensions (including warpage)The type of gate selected is dependent on both part and tool design. The gate location is equally important. To prevent the chances of jetting, locate the gate entrance in an area where the flow will impinge on a cavity wall. For automatically degating tools, the highly elastic nature of softer TPEs makes submarine gate designs or three plate tools with selfdegating drops more difficult. Higher hardness and filled grades usually have lower ultimate elongation and therefore are more easily degated. To assure the gates will break at a specific location, they should have a short land length to create a high stress concentration.Tab/Edge GatesTab or edge gates (Figure 14) most commonly utilize a conventional sprue and cold runner system. They are located along the tool parting line. A small undercut can be placed where the gate meets the part to minimize gate vestige caused by degating. Advantages of edge gates are ease of fabrication, modification and maintenance. The 14 gate depth (D) should be 15% - 30% of the wall thickness at the gate entrance. Common practice is to start “steel safe”. A good starting point for the gate width should be 1.0 - 1.5 times the gate depth. The gate land should be equal to or slightly longer than gate depth. The gate size may also depend on the part volume. The gate area may be inserted to facilitate gate maintenance or modification.Figure 14. Tab or edge gate Figure 15. Submarine GateSubmarine or tunnel gates are self-degating. During part ejection, the tool steel separates the part and the runner. Figure 15 shows a typical design of a submarine gate. Cashew type submarine gates should not be used for medium to soft hardness compounds due to their high coefficient of friction and high elongation.Fan GatesA fan gate is a streamlined variation of a tab gate (Figure 16). The fan gate distributes material into the cavity more evenly; thus it is normally used in parts that require a high degree of flatness and absence of flow lines. It also minimizes the possibility of gate pucker or part warpage.Figure 16. Fan gateSprue or Direct GateThe sprue or direct gate is often used on prototype parts because it is inexpensive. This type of gating is not recommended for GLS styrenic compounds because of their high elongation. In addition, the sprue will need to be trimmed thus appearance quality of the part is usually poor. If sprue gating is selected, care should be taken to keep both the sprue length and diameter as short and small as possible.Diaphragm GateThe diaphragm gate is used to maintain the concentricity of round parts. It allows even flow into the cavity and minimizes the potential for knit lines. Due to anisotropic shrinkage, flat round parts using center or diaphragm gating may not lay flat. A ring gate may also be used on the outside of a circular part.Table 4 compares the advantages and disadvantages of the various gate types discussed in this section.Table 4. Advantages and Disadvantages of Various Gate TypesGate TypeAdvantageDisadvantageEdge/Tab/Fan Gate Appropriate for flat parts Easy to modify Post-mold gate/runner removal is difficult Poor gate vestigeSubmarine Gate Automatic gate removal Minimal gate vestige More difficult to machineDiaphragm Gate Concentricity Appropriate for round parts No knit lines Scrap Post-molding gate removalPin gate (3-plate) Automatic gate removal Minimal gate vestige Localized cooling Requires floater plate More scrap Higher tool costValve gate (Hot runner systems) Minimal gate vestige Positive shut-off Minimizes post pack Higher tool cost Higher maintenance Only for hot runner systemsGate LocationStyrenic TPE compounds are anisotropic, thus they have different physical properties in the flow direction versus the cross-flow direction. Depending on the products intended usage, these property differences could be critical to the performance of the final part. As a result, the anisotropic nature of the styrenic TPE needs to be taken into consideration when determining the gate location on the part.The material flow may be estimated by eye or by using flow analysis programs. For higher shrinkage grades, the part may shrink near the gate, which causes “gate pucker” if there is a high molded-in stress at the gate. Parts shaped like a handle grip may warp toward the gate side of the part. Locating the gate at the top of the part minimizes this problem. Using two gates on opposite sides of the part can also address the issue, but it will result in two knit lines. If filling problems exist in thin walled parts, adding flow channels or minor changes in wall thickness can alter the flow. In some cases, it may be necessary to add a second gate to properly fill the parts.The gate should be placed so that the flow path is as short as possible. Locating the gate at the heaviest cross section of the part can improve packing and minimize voids or sinks. If possible, the gate should be positioned so as to avoid obstructions (flowing around cores or pins) in the flow path.The flow path of the material should minimize the possibility of formation of knit lines and flow marks. Upon injection, the material should impinge off the cavity wall to reduce the possibility of jetting. To minimize the effect of molded-in stress (at the gate) on part performance, the gate should be located in noncritical areas of the part. Also, the gate location should allow for easy manual or automatic degating.Mold VentingMold venting is critical to the quality and consistency of the finished part. Venting is required to allow the air in the sprue, ru
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