電表端蓋塑料件注塑模設(shè)計(jì)-抽芯注射模含14張CAD圖
電表端蓋塑料件注塑模設(shè)計(jì)-抽芯注射模含14張CAD圖,電表,塑料件,注塑,設(shè)計(jì),注射,14,cad
PBT玻璃纖維增強(qiáng)復(fù)合材料水輔注塑成型的實(shí)驗(yàn)研究
摘要:本報告的目的是通過實(shí)驗(yàn)研究聚對苯二甲酸丁二醇復(fù)合材料水輔注塑的成型工藝。實(shí)驗(yàn)在一個配備了水輔注塑統(tǒng)的80噸注塑機(jī)上進(jìn)行,包括一個水泵,一個壓力檢測器,一個注水裝置。實(shí)驗(yàn)材料包括PBT和15%玻璃纖維填充PBT的混合物以及一個中間有一個肋板的空心盤。實(shí)驗(yàn)根據(jù)水注入制品的長度的影響測得了各種工藝參數(shù)以及它們的機(jī)械性能。XRD也被用來分別材料和結(jié)構(gòu)參數(shù)。最后,作了水輔助和氣體輔助注塑件的比較。實(shí)驗(yàn)發(fā)現(xiàn)熔體壓力,熔融溫度,及短射類型是影響水注塑行為的決定性參數(shù)。材料在模具一面比在水一面展示了較高的結(jié)晶度。氣輔成型制品也要比水輔成型制品結(jié)晶度高。另外,制品表面的玻璃纖維大部分取向與流動方向一致,而隨著離制品表面距離的增加,越來越多的垂直與流動方向。
關(guān)鍵詞:水輔注塑成型,玻璃纖維增強(qiáng)PBT,工藝參數(shù),機(jī)械性能,結(jié)晶,
1.前言
依靠重量輕,成型周期短,消耗低,水輔注塑成型技術(shù)在塑料制品制造方面已經(jīng)取得了突破。在水輔注塑成型中,模具行腔被部分注入聚合物熔體,而后向這些聚合物中心注入水。水輔注塑成型的原理如圖1
圖1 水輔注塑成型的原理如圖
水輔注塑成型能夠在更短的循環(huán)時間內(nèi)生產(chǎn)出收縮小,翹曲小,表面質(zhì)量好的各種薄厚的制品。水輔注塑成型工藝也可根據(jù)工具及設(shè)備的承受壓力在設(shè)計(jì),節(jié)省材料,減輕重量,減少成本方面取得更大的自由。典型的應(yīng)用有棒,管材,水路管網(wǎng)建設(shè)用的大型復(fù)合結(jié)構(gòu)管。另一方面,盡管有很多優(yōu)勢,由于加入了額外的工藝參數(shù),模具和工藝控制變的更加嚴(yán)峻和困難。水也可能腐蝕模具鋼,同時一些材料包括熱塑性塑料難以成型。成型后水的清除也是對這個新技術(shù)的一個挑戰(zhàn)。表1列出了水輔注塑成型技術(shù)的優(yōu)勢和局限性。
優(yōu)勢
局限性
1,成型周期短
2,成本低(水更便宜而且可方便地循環(huán)利用)
3,制品內(nèi)部不產(chǎn)生泡沫現(xiàn)象。
1,水腐蝕模具
2,需要較大的注塑元件。(容易陷入聚合物熔體)
3,一些材料難以成型(尤其是非晶態(tài)熱塑性材料)
4,成型后需要清除水
表1
水輔注塑成型有優(yōu)勢超過它更有名的競爭對手,氣輔注塑成型,因?yàn)橐揽克诔尚瓦^程中更好的冷卻能力,水輔注塑成型獲得了更短的成型周期。它的不可壓縮性,低成本以及易循環(huán)利用,水成為這一過程的理想媒介。既然水不會溶解和擴(kuò)散到聚合物熔體中,那么經(jīng)常在氣輔成型工藝出現(xiàn)的氣泡現(xiàn)象也便消除了。另外,水輔注塑成型能更好的用小剩余壁厚成型大型制件。表2是對水輔和氣輔成型工藝的一個比較。
表2水輔和氣輔成型工藝比較。
水輔
氣輔
1成型周期
2介質(zhì)成本
3氣泡現(xiàn)象
5殘余壁厚
6表面粗糙度
7表面光澤
8指形效應(yīng)
9非均勻穿透
10制品透明度
11內(nèi)表面(熱塑性半晶)
12內(nèi)表面(熱固性)
短
低
無
小
小
高
大
穩(wěn)定
高
平滑
粗糙
長
高
有
大
高
低
小
不穩(wěn)定
低
粗糙
平滑
隨著對密度小,強(qiáng)度高,價格便宜,成型周期短的優(yōu)良性能材料需求的增加,塑料工程是一個不可忽視的工藝。這些塑料包括熱塑性和熱固性塑料。一般來說,熱塑性塑料以其更高的沖擊強(qiáng)度,斷裂阻力,疲勞強(qiáng)度而更有優(yōu)勢。這使得熱塑性塑料在工程建設(shè)中廣泛使用。
PBT是廣泛使用的熱塑性工程塑料之一,它有1,4—丁烯乙2醇和DMT聚合而成。玻纖增強(qiáng)混合材料適用于提高原材料的機(jī)械性能。今天,短玻璃纖維增強(qiáng)PBT已被廣泛應(yīng)用與電子,通信,汽車領(lǐng)域。所以,對玻璃纖維增強(qiáng)PBT的研究更加重要了。本文是通過實(shí)驗(yàn)研究聚對苯二甲酸丁二醇水輔注塑的成型工藝,實(shí)驗(yàn)在一個配備了水輔注塑統(tǒng)的80噸注塑機(jī)上進(jìn)行,包括一個水泵一個壓力檢測器,一個注水裝置。實(shí)驗(yàn)材料包括PBT和15%玻璃纖維填充PBT的混合物以及一個中間有一個肋板的空心盤。實(shí)驗(yàn)根據(jù)水注入制品的長度的影響測得了各種工藝參數(shù)以及它們的機(jī)械性能。XRD也被用來分別材料和結(jié)構(gòu)參數(shù)。最后,作了水輔助和氣體輔助注塑件的比較。
2.實(shí)驗(yàn)步驟
2.1 材料
實(shí)驗(yàn)材料包括PBT(牌號1111FB,南亞塑料,臺灣)和15%玻璃纖維填充PBT的混合物(牌號1210G3,南亞塑料,臺灣)。表3列出了此混合材料的特征。
表3 纖維增強(qiáng)PBT復(fù)合材料特征
性質(zhì)
ASTM
PBT
15%G.F.PBT
屈服應(yīng)力(kg/cm2)
彎曲應(yīng)力(kg/cm2)
硬度
熱變形溫度(℃)
MFI
沖擊強(qiáng)度
熔點(diǎn)(℃)
D-638
D-570
D-785
D-648
D-1238
D-256
DSC
600
900
119
60
40
5
224
1000
1500
120
200
25
5
224
2.2 水輔注塑元件
一個實(shí)驗(yàn)室注水元件,包括一個水泵,一個壓力檢測器,一個注水閥,一個配備了溫度調(diào)節(jié)裝置的水箱,以及一個控制電路。這個孔板型注水閥每邊有兩個孔,用來成型制件。實(shí)驗(yàn)過程中,注水閥的控制電路收到由注塑機(jī)產(chǎn)生的信號實(shí)現(xiàn)對時間和注水壓力的控制。在注入模具行腔之前,水在有溫控裝置的水箱里加熱30分鐘。
2.3注塑機(jī)和模具
水輔注塑成型實(shí)驗(yàn)在一個最高注塑速率109cm3/s的80噸注塑機(jī)上進(jìn)行。研究使用了一個中間有一個肋板的空心盤。圖2顯示了這個行腔的尺寸。模具溫度由一個水循環(huán)模溫控制元件調(diào)節(jié)。實(shí)驗(yàn)根據(jù)水注入制品的長度的影響測得了各種工藝參數(shù),包括熔體溫度,模具溫度,熔體充模壓力,水溫和水壓,注水延遲時間和保持時間,以及熔體短射類型。表4列出這些工藝參數(shù)及在實(shí)驗(yàn)中的數(shù)值。
A
B
C
D
E
F
熔體壓力
熔體溫度
短射類型
水 壓
水 溫
模具溫度
140
126
114
98
84
280
275
270
265
260
76
77
78
80
81
8
9
10
11
12
80
75
70
65
60
80
75
70
65
60
表 4
2.4氣輔注塑元件
為了對水輔和氣輔注塑成型制件進(jìn)行比較,氣輔注塑成型實(shí)驗(yàn)使用了一個商用氣輔注塑成型元件,其具體配置可參考RCFS。氣輔注塑成型工藝控制和水輔注塑成型一樣,除了氣體溫度設(shè)置為25外。
圖2 模具行腔的尺寸和外形
2.5 XRD
為了分析水輔注塑成型制品的晶體結(jié)構(gòu),實(shí)驗(yàn)使用了具有二維探測分析傳輸模式的廣角X射線衍射儀。更特別的是實(shí)驗(yàn)對水輔注塑成型制品模具一邊和水一邊的樣品在7到40的范圍內(nèi)進(jìn)行測量。分析所用的樣品來自制品中心。為了獲得XRD樣品要求的厚度,多余的部分在一個旋轉(zhuǎn)輪上打磨掉。首先用濕的碳硅紗布,而后用粒度300的,再用粒度600和1200的,以獲得更好的表面質(zhì)量。
2.6機(jī)械性能
拉伸強(qiáng)度和彎曲強(qiáng)度測試在一個拉力測試機(jī)上進(jìn)行。實(shí)驗(yàn)對水輔注塑成型制件樣本進(jìn)行拉力測試以評估水溫對拉伸性能的影響。樣本的尺寸為30mm*10mm*1mm.
水輔注塑成型制件的彎曲實(shí)驗(yàn)也在室溫下進(jìn)行。彎曲樣本的尺寸為20mm*10mm*1mm。
3 結(jié)論
本報告的目的是通過實(shí)驗(yàn)研究聚對苯二甲酸丁二醇復(fù)合材料水輔注塑的成型工藝?;诋?dāng)前實(shí)驗(yàn)可得出以下結(jié)論
1. 水輔注塑成型制品在水道的過度區(qū)域出現(xiàn)了指形效應(yīng)。并且,玻璃纖維增強(qiáng)復(fù)合材料的指形效應(yīng)比不增強(qiáng)的更嚴(yán)重
2. 研究的實(shí)驗(yàn)結(jié)果顯示PBT復(fù)合材料的水穿透長度隨著水溫和水壓的增加而增加。隨著熔體充模壓力,熔體溫度,模具溫度,短射量的增加而降低。,
3. 制品的翹曲隨著水穿透的程度而降低了。
4. 注塑制品的結(jié)晶度隨著水溫的升高而提高。水輔成型制品的結(jié)晶度比氣輔的要低。
5. 模具一邊的制品表面的玻璃纖維取向大部分與流動方向一致,而隨著離這一表面距離的增加,纖維取向逐漸的垂直與流動方向。
6
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設(shè)計(jì)開題報告
課 題 名 稱: 電表端蓋塑料件注塑模設(shè)計(jì)
學(xué) 生 姓 名: XXXXX
指 導(dǎo) 教 師: XXXX
所 在 學(xué) 院: XXX
專 業(yè) 名 稱: XXX
(XXX)
20XXX年 月 日
開題報告
學(xué)生姓名
學(xué) 號
專 業(yè)
指導(dǎo)教師
姓名
職 稱
講師
所在系部
課題來源
自擬課題
課題性質(zhì)
工程技術(shù)研究
課題名稱
電表端蓋塑料件注塑模設(shè)計(jì)
畢業(yè)設(shè)計(jì)的內(nèi)容和意義?
1. 主要內(nèi)容:
(1)編寫模具技術(shù)要求、模具材料的確定;
(2)使用UG軟件進(jìn)行模具型芯和型腔的分模,完成模具的2D總裝圖和若干零件圖的繪制。掌握塑件成型工藝性分析,注塑機(jī)的選擇,注塑模具分型面的選取,模腔數(shù)目及排列、澆注系統(tǒng)、模架與成型零件、抽芯機(jī)構(gòu)、推出機(jī)構(gòu)和復(fù)位機(jī)構(gòu)、溫度調(diào)節(jié)系統(tǒng)的設(shè)計(jì)。
(3)掌握塑料的使用性能和用途。完成與模具相關(guān)資料的外文翻譯。
(4)掌握模具鋼的使用情況,了解企業(yè)的模具設(shè)計(jì)流程和制造情況。掌握新軟件使用和模具加工的新工藝。
(5)利用模具分析進(jìn)行熔體模擬流動分析,優(yōu)化模具設(shè)計(jì)結(jié)構(gòu)。
2.畢業(yè)設(shè)計(jì)的意義:
畢業(yè)設(shè)計(jì)是在教師的指導(dǎo)下,運(yùn)用已學(xué)的知識、獨(dú)立進(jìn)行科學(xué)研究活動,學(xué)會分析和解決學(xué)術(shù)問題的方法,鍛煉解決某一學(xué)術(shù)問題的能力。是對我們的知識能力進(jìn)行一次全面的考核,同時也是對我們進(jìn)行科學(xué)研究基本功的訓(xùn)練,培養(yǎng)綜合運(yùn)用所學(xué)知識獨(dú)立地分析問題和解決問題的能力,為以后工作打下良好的基礎(chǔ)。
進(jìn)行畢業(yè)設(shè)計(jì)是對我們進(jìn)行最后一次知識的全面檢驗(yàn),是對我們基本知識、基本理論和基本技能掌握與提高程度的一次總測試,這是進(jìn)行畢業(yè)設(shè)計(jì)的第一個目的。我們在學(xué)習(xí)期間,已經(jīng)按照學(xué)校的規(guī)定,學(xué)完了公共課、基礎(chǔ)課、專業(yè)課以及選修課等,每門課程也都經(jīng)過了考試或考查。學(xué)習(xí)期間的這種考核是單科進(jìn)行,主要是考查我們對本門學(xué)科所學(xué)知識的記憶程度和理解程度。但畢業(yè)設(shè)計(jì)則不同,它不是單一地對我們進(jìn)行某一學(xué)科已學(xué)知識的考核,而是著重考查我們運(yùn)用所學(xué)知識對某一問題進(jìn)行探討和研究的能力,是培養(yǎng)我們綜合運(yùn)用所學(xué)的基礎(chǔ)理論、專業(yè)知識、基本技能,研究和解決問題的能力。是讓我們對四年所學(xué)知識和技能進(jìn)行系統(tǒng)化、綜合化運(yùn)用、總結(jié)和深化的過程。通過這個過程,鍛煉了我們的思維能力、動手能力,并加深了我們掌握知識的深度理解。
文獻(xiàn)綜述
塑料工業(yè)是當(dāng)今世界上增長最快的工業(yè)門類之一,掌握塑料產(chǎn)品的生產(chǎn)過程對提高產(chǎn)品質(zhì)量有很大意義[1]。在機(jī)械制造業(yè)中,隨著全球市場競爭的日益激烈,各企業(yè)都力求以最好質(zhì)量、最低成本、最快速度將產(chǎn)品推向市場,計(jì)算機(jī)模擬技術(shù)得以充分用用。在傳統(tǒng)模具設(shè)計(jì)制造過程中,模具制造完畢后要進(jìn)行多次試模、修模。反復(fù)的修模會造成模具內(nèi)部品質(zhì)的變化,導(dǎo)致整副模具.性能降低,從而使最終塑料制品質(zhì)量不能達(dá)到標(biāo)準(zhǔn)。而使用計(jì)算機(jī)輔助技術(shù)不僅可提高一次性試模的成功率,而且還可以使模具在質(zhì)量、性能及成本上都有很大程度的提高[2]。通過本次設(shè)計(jì)掌握先進(jìn)軟件技術(shù),用專業(yè)分析軟件moldflow和軟件EMX4.1來縮短設(shè)計(jì)周期,提高一次性試模的成功率。本設(shè)計(jì)還通過電熱毯開關(guān)的注塑模具設(shè)計(jì),了解注塑模具制造特點(diǎn)和新興注射成型技術(shù)對模具制造的新要求,分析注塑模具制造技術(shù)中的幾個關(guān)鍵問題。
模具具有明顯的效益擴(kuò)大作用,用模具生產(chǎn)出來的最終產(chǎn)品價值,往往是模具自身價值的幾十倍,幾百倍,甚至更多。用模具生產(chǎn)制件所具備的高精度、高復(fù)雜程度、高一致性,高生產(chǎn)率和代消耗,是其他加工方法所不能比擬的。注塑模具的發(fā)展日新月異,掌握注塑模具設(shè)計(jì)及其專業(yè)分析軟件,對未來的注塑模具設(shè)計(jì)市場有著不可估量的意義,對個人今后的事業(yè)有著不同尋常的意義。世界工業(yè)經(jīng)濟(jì)和科學(xué)技術(shù)的發(fā)展,帶動了模具制造業(yè)的迅速發(fā)展。在現(xiàn)代工業(yè)生產(chǎn)中,模具是最重要的工藝裝備之一[3]。采用模具進(jìn)行生產(chǎn)能提高生產(chǎn)效率,節(jié)約原材料,降低成本,并保證一定的加工質(zhì)量要求。模具已經(jīng)成為現(xiàn)代工業(yè)生產(chǎn)的主要成型工具。模具行業(yè)是制造業(yè)的重要組成部分,模具生產(chǎn)水平的高低已經(jīng)成為一個國家制造水平高低的重要標(biāo)志,因?yàn)槟>咴诤艽蟪潭壬蠜Q定著產(chǎn)品的質(zhì)量、效益和新產(chǎn)品的開發(fā)能力[4]。模具是工業(yè)生產(chǎn)的基礎(chǔ)工藝裝備。在電子、汽車、電器、儀器、儀表、家電和通信等產(chǎn)品中,60%-80%的零部件都要依靠模具成型。塑料,橡膠,陶瓷,玻璃,皮革,耐火材料以及建材制品等大部分產(chǎn)品也都是采用模具成型[5]。
文獻(xiàn)綜述
國外從6O年代初就開始了模具CAD/CAM的應(yīng)用研究工作,到7O年代已研制了模具CAD/CAM的專門系統(tǒng),可應(yīng)用于各種類型的模具設(shè)計(jì)和制造,并取得了顯著效果,受到世界各國的普遍重視。目前國際上注塑模CAD/CAM的發(fā)展趨勢是:(1)進(jìn)一步完善注塑工藝過程的模擬程序,特別是流動模擬和冷卻分析程序。已問世的商品化軟件,無是Mo]dFlow、C—Flow,還是Polycool、Blycoo12等,在使用中都有一些問題,有時甚至于在此出現(xiàn)明顯的話誤。因此,如何建立更為符合實(shí)際、又能迅速求解的三維非牛頓流體、非等溫流動過程數(shù)學(xué)模型和三維非穩(wěn)態(tài)冷卻過程數(shù)學(xué)模型,仍是國際上致力研究和急待解決的問題。(2)注塑模CAD/CAM的一體化工作,為了向用戶提供更實(shí)用、更方便的注塑模C&D/CAM軟件,國外許多計(jì)算機(jī)公司正在開發(fā)集成化程序更高的注塑模CAD/CAM系統(tǒng)。(3)建立專家系統(tǒng),改善注塑模設(shè)計(jì)質(zhì)量、提高注塑制品的生產(chǎn)效率。目前,國外已出現(xiàn)了一些注塑棋的專家系統(tǒng),能夠幫助用戶分析注塑制品的缺陷,選擇注塑模具的最佳分型面,對模具零件的結(jié)構(gòu)進(jìn)行優(yōu)化等。
由于硬件資源的影響,我國模具CAD/CAM的研究工作起步較晚。但是現(xiàn)在我國在逐漸成熟CAD/CAM技術(shù)支持下進(jìn)行二次開發(fā),能通過計(jì)算機(jī)對產(chǎn)品、模具結(jié)構(gòu)、成形工藝、數(shù)控加工及成本等進(jìn)行設(shè)計(jì)和優(yōu)化,能顯著縮短模具設(shè)計(jì)與制造周期,降低生產(chǎn)成本,提高產(chǎn)品質(zhì)量,國內(nèi)的各大高校及研究機(jī)構(gòu)也對SolidWorks、AutoCAD、Pro/Engineer、UniGraphics等熟悉的軟件進(jìn)行開發(fā)探索,例如山東大學(xué)材料液態(tài)結(jié)構(gòu)及其遺傳性教育部重點(diǎn)實(shí)驗(yàn)室的李成棟、田學(xué)雷、王培風(fēng)等開發(fā)的鑄件材料庫管理系統(tǒng)、以及哈爾濱工業(yè)大學(xué)、江南大學(xué)和上海交通大學(xué)等高校也開始了對Pro/E的開發(fā),但他們的開發(fā)也只是面對某中具體零件的開發(fā),很少涉及到與其它軟件的接合開發(fā),這樣就限制了Pro/E的開發(fā)空間,使得開發(fā)結(jié)果不夠理想。研究軟件間的開發(fā)接口,實(shí)現(xiàn)軟件資源共享,可以權(quán)衡利弊,優(yōu)勢互補(bǔ),開發(fā)后的軟件更加實(shí)用、方便快捷。
國內(nèi)CAD/CAM技術(shù)發(fā)展使得下一個世紀(jì)多品種、少批量生產(chǎn)方式占工業(yè)生產(chǎn)的比例將達(dá)75%以上。一方面是制品使用周期短,品種更新快,另一方面制品的花樣變化頻繁,均要求模具的生產(chǎn)周期越快越好。因此,開發(fā)快速經(jīng)濟(jì)具簡單易操作的模具設(shè)計(jì)應(yīng)用程序?qū)⒃絹碓揭鹑藗兊闹匾暻揖哂泻艽蟮纳虡I(yè)價值。
通過編寫語言程序來對Pro/E系統(tǒng)進(jìn)行二次開發(fā),研制出適合各模具企業(yè)設(shè)計(jì)生產(chǎn)要求的CAD系統(tǒng),可以節(jié)省模具的設(shè)計(jì)時間,提高模具制造的效率,使用模具CAD系統(tǒng),可以節(jié)省技術(shù)也會越來越成熟,必將對我國的模具行業(yè)的發(fā)展起到重要作用。
參考文獻(xiàn)
參考文獻(xiàn)
[1] 鄭生榮.嵌件注塑成型工藝的特點(diǎn)[J].模具工業(yè),2008(11):38-41.
[2] 艾方.精密注塑模具[J].模具技術(shù),1993(5):67-71.
[3] 李建國.注射模成型零件工作尺寸計(jì)算方法分析[J].模具工業(yè),2003(11):38-41.
[4] 駱志文.注射模冷卻時間計(jì)算分析[J].模具工業(yè),1994(3):29-34.
[5] 王建華,徐佩弦. 注射模的熱流道技術(shù)[M]. 北京:機(jī)械工業(yè)出版社,2006.
[6] 袁中雙,李德群.注塑成形的流動平衡分析[J].模具技術(shù),94(1):12-16.
[7] 申長雨.注射模保壓過程的數(shù)值模擬和塑料的收縮分析[J].模具工業(yè),2001(5):48-52.
[8] 葉久新,王群.塑料成型工藝及模具設(shè)計(jì).北京:機(jī)械工業(yè)出版社,2007::25-240.
[9] 鄭生榮,辛勇.注射工藝參數(shù)的快速確定方法[J].模具工業(yè),2003(12):9-37.
[10] 何華妹,杜智敏,伍柳機(jī),《注塑模具設(shè)計(jì)實(shí)例精解》,清華大學(xué)出版社,2005.9
[11] JANSEN K M B. Heat transfer in injection moulding systems with insulation layers and heating
elements [J]. International journal of heat and mass transfer, 1995, 38(2):309-316.
[12] YAO D G, KIM B. Development of rapid heating and cooling systems for injection molding applications [J]. Polymer Engineering & Science, 2002 , 42(12):2471-2481.
[13] 吳生緒.塑料成形模具設(shè)計(jì)手冊[M].機(jī)械工業(yè)出版社
[14] 朱光力,萬金保等.塑料模具設(shè)計(jì)(第2版) [M].北京:清華大學(xué)出版2006:48-52.
[15] 楊予勇.塑料成型工藝與模具設(shè)計(jì)[M].北京:國防工業(yè)出版社,2007:52-66.
1.設(shè)計(jì)、研究思路:
本畢業(yè)設(shè)計(jì)分以下步驟進(jìn)行;
(a)認(rèn)真跟老師溝通,了解所要設(shè)計(jì)的產(chǎn)品;
(b)了解設(shè)計(jì)的大概思路;
(c)查閱大量資料,確定設(shè)計(jì)方案;
(d)跟老師溝通,看有無出錯;
(e)熟悉各類軟件,如AutoCAD,PRO/E,MOLDFLOW 等;
(f)完成畢業(yè)設(shè)計(jì)的一系列任務(wù);
2.課題研究的主要內(nèi)容
如圖所示為該塑料件的結(jié)構(gòu),我們可以看出該制件可以簡化為一殼體,在設(shè)計(jì)過程中應(yīng)該從產(chǎn)品的結(jié)構(gòu)特點(diǎn)和模具的制造加工工藝出發(fā)盡量簡化模具的結(jié)構(gòu)。分型面選取為該制件的最底面位置,澆口選擇為側(cè)澆口,頂出方式選擇多根頂桿推出結(jié)構(gòu),最后采取一模2腔的結(jié)構(gòu)平衡布置型腔。
3.解決的關(guān)鍵問題
本塑件外表面有一個側(cè)凹槽,一個側(cè)孔,棱角應(yīng)該為圓弧過渡。設(shè)計(jì)過程中需要解決的主要問題有:
1)選擇分型面。
2)確定模具結(jié)構(gòu)。
3)確定型腔的數(shù)目。
4)型腔的布置。
5)側(cè)孔的成型,確定抽芯機(jī)構(gòu)的類型。
6)確定澆注系統(tǒng)類型。
7)選擇注射機(jī)類型、大小等。
8)確定脫模方式,選擇推出機(jī)構(gòu)的類型。
9)確定開模方向。
10)塑料充模的流動分析,預(yù)期成型時可能出現(xiàn)的缺陷。
11)選擇模架,計(jì)算模板的大小。
12)注射機(jī)技術(shù)參數(shù)、模板強(qiáng)度等校核。
這些問題都是設(shè)計(jì)該模具的關(guān)鍵問題,在設(shè)計(jì)過程中,本人將通過查閱有關(guān)文獻(xiàn)資料來解決。
4.預(yù)期成果
(1)該塑料件模具技術(shù)要求一份、訂料表文件一份;
(2)開題報告一份、外文翻譯資料一份;
(3)3D開模圖一份;
(4)2D裝配圖一份和零件圖若干份(不少于3張A0圖紙);
(5)畢業(yè)論文一份;
(6)熔體模擬流動分析,優(yōu)化模具設(shè)計(jì)結(jié)構(gòu)報告;
研究計(jì)劃
1.第 1~2 周 查閱技術(shù)文獻(xiàn)資料,了解課題相關(guān)領(lǐng)域的最新發(fā)展動態(tài),翻譯外文相關(guān)技術(shù)資料2000字以上;
2.第 3 周 編寫開題報告;
3.第 4~5 周 熟悉對Pro/E、cad的實(shí)際操作和有關(guān)功能,完成標(biāo)準(zhǔn)零件的造型及關(guān)系式的建立;
4.第 6~8 周 建立標(biāo)準(zhǔn)零件庫、材料庫,完成模具方案的分析;
5.第 9~10 周 進(jìn)行成型零部件的造型,并進(jìn)行總體裝配,繪制模具裝備圖出圖,繪制模具所有非標(biāo)準(zhǔn)零件圖;
6.第 11 周 整理文檔,編寫畢業(yè)論文;
7.第 12 周 論文答辯。
特色與創(chuàng)新
在本次畢業(yè)設(shè)計(jì),本人將全部應(yīng)用CAD/CAE/CAM技術(shù)來設(shè)計(jì)與制造模具。在模具設(shè)計(jì)方面,應(yīng)用PRO/E軟件對模具型芯和型腔進(jìn)行3D分模,并完成三維模具總裝圖;使用MOLDFLOW軟件對注射成型過程進(jìn)行了3D數(shù)值模擬,從而優(yōu)化了模具結(jié)構(gòu)。由于學(xué)習(xí)該軟件需要一定的塑件成型實(shí)踐知識,在使用上要多查閱這方面的資料。
指導(dǎo)教師
意 見
指導(dǎo)教師簽名:
2015年 月 日
教研室意見
主任簽名:
2015 年 月 日
學(xué)院(系部)意見
教學(xué)院長(主任)簽名:
2015年 月 日
6
An experimental study of the water-assisted injection molding of glass ?ber ?lled poly-butylene-terephthalate (PBT) composites
Abstract
The purpose of this report was to experimentally study the water-assisted injection molding process of poly-butylene-terephthalate (PBT) composites. Experiments were carried out on an 80-ton injection-molding machine equipped with a lab scale water injection system, which included a water pump, a pressure accumulator, a water injection pin, a water tank equipped with a temperature regulator, and a control circuit. The materials included virgin PBT and a 15% glass ?ber ?lled PBT composite, and a plate cavity with a rib across center was used. Various processing variables were examined in terms of their in?uence on the length of water penetration in molded parts, and mechanical property tests were performed on these parts. X-ray di?raction (XRD) was also used to identify the material and structural parameters. Finally, a comparison was made between water-assisted and gas-assisted injection molded parts. It was found that the melt ?ll pressure, melt temperature, and short shot size were the dominant parameters a?ecting water penetration behavior. Material at the mold-side exhibited a higher degree of crystallinity than that at the water-side. Parts molded by gas also showed a higher degree of crystallinity than those molded by water. Furthermore, the glass ?bers near the surface of molded parts were found to be oriented mostly in the ?ow direction, but oriented substantially more perpendicular to the ?ow direction with increasing distance from the skin surface.
2006 Elsevier Ltd. All rights reserved.
Keywords: Water assisted injection molding; Glass ?ber reinforced poly-butylene-terephthalate (PBT) composites; Processing parameters; B. Mechanical properties; Crystallinity; A. Polymer matrix composites; Processing
1. Introduction
Water-assisted injection molding technology [1] has proved itself a breakthrough in the manufacture of plastic parts due to its light weight, faster cycle time, and relatively lower resin cost per part. In the water-assisted injection molding process, the mold cavity is partially ?lled with the polymer melt followed by the injection of water into the core of the polymer melt. A schematic diagram of the water-assisted injection molding process is illustrated in Fig. 1. Water-assisted injection molding can produce parts incorporating both thick and thin sections with less shrinkage and warpage and with a better surface ?nish, but with a shorter cycle time. The water-assisted injection molding process can also enable greater freedom of design, material savings, weight reduction, and cost savings in terms of tooling and press capacity requirements [2–4]. Typical applications include rods and tubes, and large sheet-like structural parts with a built-in water channel network. On the other hand, despite the advantages associated with the process, the molding window and process control are more critical and di?cult since additional processing parameters are involved. Water may also corrode the steel mold, and some materials including thermoplastic composites are di?cult to mold successfully. The removal of water after molding is also a challenge for this novel technology. Table 1 lists the advantages and limitations of water-assisted injection molding technology.
Water assisted injection molding has advantages over its better known competitor process, gas assisted injection molding [5], because it incorporates a shorter cycle time to successfully mold a part due to the higher cooling capacity of water during the molding process. The incompressibility, low cost, and ease of recycling the water makes it an ideal medium for the process. Since water does not dissolve and di?use into the polymer melts during the molding process, the internal foaming phenomenon [6] that usually occurs in gas-assisted injection molded parts can be eliminated. In addition, water assisted injection molding provides a better capability of molding larger parts with a small residual wall thickness. Table 2 lists a comparison of water and gas assisted injection molding.
With increasing demands for materials with improved performance, which may be characterized by the criteria of lower weight, higher strength, and a faster and cheape production cycle time, the engineering of plastics is a process that cannot be ignored. These plastics include thermoplastic and thermoset polymers. In general, thermoplastic polymers have an advantage over thermoset polymers in terms of higher impact strength, fracture resistance and strains-to-failure. This makes thermoplastic polymers very popular materials in structural applications.
Poly-butylene-terephthalate (PBT) is one of the most frequently used engineering thermoplastic materials, which is formed by polymerizing 1.4 butylene glycol and DMT together. Fiber-reinforced composite materials have been adapted to improve the mechanical properties of neat plastic materials. Today, short glass ?ber reinforced PBT is widely used in electronic, communication and automobile applications. Therefore, the investigation of the processing of ?ber-reinforced PBT is becoming increasingly important [7–10].
This report was made to experimentally study the waterassisted injection molding process of poly-butylene-tere-phthalate (PBT) materials. Experiments were carried out on an 80-ton injection-molding machine equipped with a lab scale water injection system, which included a water pump, a pressure accumulator, a water injection pin, a water tank equipped with a temperature regulator, and a control circuit. The materials included a virgin PBT and a 15% glass ?ber ?lled PBT composite, and a plate cavity with a rib across center was used. Various processing variables were examined in terms of their in?uence on the length of water penetration in molded parts, which included melt temperature, mold temperature, melt ?lling speed, short-shot size, water pressure, water temperature, water hold and water injection delay time. Mechanical property tests were also performed on these molded parts, and XRD was used to identify the material and structural parameters. Finally, a comparison was made between water-assisted and gas-assisted injection molded parts.
2. Experimental procedure
2.1. Materials
The materials used included a virgin PBT (Grade 1111FB, Nan-Ya Plastic, Taiwan) and a 15% glass ?ber ?lled PBT composite (Grade 1210G3, Nan-Ya Plastic, Taiwan). Table 3 lists the characteristics of the composite materials.
2.2. Water injection unit
A lab scale water injection unit, which included a water pump, a pressure accumulator, a water injection pin, a water tank equipped with a temperature regulator, and a control circuit, was used for all experiments [3]. An ori- ?ce-type water injection pin with two ori?ces (0.3 mm in diameter) on the sides was used to mold the parts. During the experiments, the control circuit of the water injection unit received a signal from the molding machine and controlled the time and pressure of the injected water. Before injection into the mold cavity, the water was stored in a tank with a temperature regulator for 30 min to sustain an isothermal water temperature.
2.3. Molding machine and molds
Water-assisted injection molding experiments were conducted on an 80-ton conventional injection-molding machine with a highest injection rate of 109 cm3/s. A plate cavity with a trapezoidal water channel across the center was used in this study.Fig. 2 shows the dimensions of the cavity. The temperature of the mold was regulated by a water-circulating mold temperature control unit. Various processing variables were examined in terms of their in?uence on the length of water penetration in water channels of molded parts: melt temperature, mold temperature, melt ?ll pressure, water temperature and pressure, water injection delay time and hold time, and short shot size of the polymer melt. Table 4 lists these processing variables as well as the values used in the experiments
2.4. Gas injection unit
In order to make a comparison of water and gas-assisted injection molded parts, a commercially available gas injection unit (Gas Injection PPC-1000) was used for the gasassisted injection molding experiments. Details of the gas injection unit setup can be found in the Refs. [11–15]. The processing conditions used for gas-assisted injection molding were the same as that of water-assisted injection molding (terms in bold in Table 4), with the exception of gas temperature which was set at 20℃.
2.5. XRD
In order to analyze the crystal structure within the water-assisted injection-molded parts, wide-angle X-ray di?raction (XRD) with 2D detector analyses in transmis-XRD samples, the excess was removed by polishing the 40 kV and 40 mA. More speci?cally, the measurements were performed on the mold-side and water-side layers of the water-assisted injection-molded parts, with the 2h angle ranging from 7 to 40 . The samples required for these analyses were taken from the center portion of these molded parts. To obtain the desired thickness for the sion mode were performed with Cu Ka radiation at samples on a rotating wheel on a rotating wheel, ?rst with wet silicon carbide papers, then with 300-grade silicon carbide paper, followed by 600- and 1200-grade paper for a better surface smoothness.
2.6. Mechanical properties
Tensile strength and bending strength were measured on a tensile tester. Tensile tests were performed on specimens obtained from the water-assisted injection molded parts (see Fig. 3) to evaluate the e?ect of water temperature on the tensile properties. The dimensions of specimens for the experiments were 30 mm · 10 mm · 1 mm. Tensile tests were performed in a LLOYD tensiometer according to the ASTM D638M test. A 2.5 kN load cell was used and the crosshead speed was 50 mm/min. Bending tests were also performed at room temperature on water-assisted injection molded parts. The bending specimens were obtained with a die cutter from parts subjected to various water temperatures. The dimensions of the specimens were 20 mm · 10 mm · 1 mm. Bending tests were performed in a micro tensile tester according to the ASTM D256 test. A 200 N load cell was used and the crosshead speed was 50 mm/min.
3. Conclusions
This report was made to experimentally study the waterassisted injection molding process of poly-butylene-tere-phthalate (PBT) composites. The following conclusions can be drawn based on the current study.
1. Water-assisted injection molded PBT parts exhibit the ?ngering phenomenon at the channel to plate transition areas. In addition, glass ?ber ?lled composites exhibit more severe water ?ngerings than those of non-?lled materials.
2. The experimental results in this study suggest that the length of water penetration in PBT composite materials increases with water pressure and temperature, and decreases with melt ?ll pressure, melt temperature, and short shot size.
3. Part warpage of molded materials decreases with the length of water penetration.
4. The level of crystallinity of molded parts increases with the water temperature. Parts molded by water show a lower level of crystallinity than those molded by gas.
5. The glass ?bers near the surface of molded PBT composite parts were found to be oriented mostly in the ?ow direction, and oriented substantially perpendicular to the ?ow direction with increasing distance from the skin surface.
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參考文獻(xiàn)
[1] Miguel S′anchez-Soto . Optimising the gas-injection moulding of an automobile plastic cover using an experimental design procedure. Spain.2006
[2] Integrated microfluidic systems for automatic glucose sensing and insulin injection
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