蓋注塑成型工藝及模具設(shè)計【盒蓋類零件】【一模四腔】【說明書+CAD】

蓋注塑成型工藝及模具設(shè)計【盒蓋類零件】【一模四腔】【說明書+CAD】,盒蓋類零件,一模四腔,說明書+CAD,蓋注塑成型工藝及模具設(shè)計【盒蓋類零件】【一模四腔】【說明書+CAD】,注塑,成型,工藝,模具設(shè)計,盒蓋,零件,說明書,仿單,cad International Journal of Machine Tools Stereolithography; Rapid tooling; Injection moulding techniques are improving and are becoming increasingly process 10. It has shown that SL injection mould tooling (Fig. 1). The back-filled mixture added strength to the inserts and allowed heat to be conducted away from the mould. The modular steel mould bases were two standard ARTICLE IN PRESS C3 Corresponding author. base plates machined with a cylindrical pocket to fit the steel frames and the inserts 12. The SL tools were then tested in a 50ton Battenfeld production moulding machine 0890-6955/$-see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijmachtools.2006.09.022 E-mail address: (S. Rahmati). 1 Professor (b) Flexural failure; (c) Shear failure. Tools & Manufacture 47 (2007) 740747 application of computational fluid dynamics (CFD) and finite element method (FEM), which will combine the fluid and stress analysis to model the SL tool. 5.2. Crack propagation and fatigue Flexural stresses can also induce a fatigue type process, spanning a number of moulding cycles. In this situation, the cube pivots as in Fig. 8(b) without being fractured but a crack is initiated at the intersection between the face of the cube in tension due to flexural stresses, and the core face perpendicular to it. During subsequent cycles, the crack propagates through the base of the cube eventually resulting in failure. Failure analysis of the SEM images has revealed that the crack propagates through the cubes prior to the ultimate failure. Micro- scopic pictures of mouldings numbered sequentially indicate that the crack has started well before the ultimate flexural failure. Fig. 10 is a picture taken of the cross section of a moulding before the actual failure happened, where subsequent injection mouldings have exhibited a positive flaw corresponding to the inverse of the crack generated. Fig. 11 shows the flexural failure of a similar cube to that seen in Fig. 10, after a number of shots. Crack initiation in SL tools occurs predominately at stress concentrations, such as sharp corners or at stair steppings (an inherent property of SL parts). Crack Fig. 10. Moulding showing the attached plastic of crack before failure. ARTICLE IN PRESS MachineS. Rahmati, P. Dickens / International Journal of formation may also result from flaws or microscopic defects created during photo-polymerisation process due to material discontinuities 15. Sharp corners, stair stepping, voids or flaws are a cause or source of crack initiation. Fatigue failure can be minimised by introducing fillets at the sharp corners in order to reduce the stress concentration and crack propagation. Evidence of the crack failure as shown in Fig. 12, can be seen on the fracture surface in the form of striations, where each one of these marks represents crack growth. At the tip of the crack and in a small region near the tip, the yield strength of the material is exceeded. In this region, plastic deformation occurs and the stresses are limited by yielding 17. After each cycle, the crack grows in the same manner until a critical crack length is reached. At this point, the crack tip can increase in velocity and spread all the way across the cube resulting in failure. Fig. 11. Flexural failure as a result of crack propagation. Fig. 12. SEM observation revealing striation marking on the fractured surface. 5.3. Shear failure During shear failure, the feature is sheared off in the direction of the melt flow. Fig. 13, shows the cross section of a sheared SL cube. Notice that the SL cube has been pushed across by the flow of plastic. The shear stress at a point in a section is given by 18: t VQ Ia , (2) where V is the shear force at the given section, Q is the first moment of the area about the neutral axis, I is the moment of inertia of the cube section with respect to the neutral axis, and a is the width of the cross-section. As the shear stress calculation results show in Table 2, the maximum shear stresses produced in the SL tool during operation are below the shear strength of the SL tool. Moreover, the SL Fig. 13. SL cube being sheared off during injection moulding process. Tools & Manufacture 47 (2007) 740747 745 tool can survive at injection temperatures beyond 401Cas shown in the last column of the Table 2. Fig. 14, shows the maximum shear stresses at various points of the cube base versus the average shear stress. The plot of the maximum shear stresses at various points results in a parabolic curve. 6. Conclusions SL tools have been successfully tested where failures were observed after 500 shots. SL tool failure mechanisms have been investigated and different scenarios have been demonstrated. Using a thermoplastic with a melting temperature of 2003001C in epoxy SL tooling which has a Glass transition temperature (T g ) of about 60901C, seems unrealistic or impossible. However, the key point to the success of this technique is the very low thermal conductivity of the SL tool and the short injection time (Fig. 15). These two factors are the key to the success of the SL injection mould tooling, which are overlooked by many. ARTICLE IN PRESS stress Machine Table 2 Shear stresses acting on the SL cubes Shear area A S (mm 2 ) Shear force V (N) Shear Cube 1 36 421.64 11.71 Cube 2 30 421.64 14.05 Cube 3 24 421.64 17.57 Cube 4 18 421.64 23.42 0 S. Rahmati, P. Dickens / International Journal of746 Although epoxy has a very low tensile or shear strength at high temperatures, during the first few seconds of injection in which the maximum pressure is exerted on the tool, the heat has not been able to penetrate. Therefore, the tool strength is still maintained and low conductivity of the epoxy works in favour of the process initially. It can be concluded that the tool must be cooled down in each cycle to as low as 40501C before the next injection is made. Tool cooling can be achieved either through free convection, which takes 45min or through forced convection by means of an air jet which reduces the cycle time to 1, 2min. The results of the work can be summarised as follows: 1/4 N.A. 1/2 0 Fig. 14. Distribution of the shear stresses 0 200 400 600 800 1000 1200 1400 1600 1800 0 1020304050 Pressure (psi) Time (sec) Fig. 15. Plot of temperature and pressure C15 C15 C15 C15 versus average shear stress 24.3 55.9 24.3 46.4 t ave (Mpa) Shear strength at 401C (Mpa) T MAX (1C) 24.3 65.3 24.3 61.5 Tools & Manufacture 47 (2007) 740747 More than 500 parts were produced using the epoxy SL core and cavity using external air jet to cool the tool to 451C. Tool failure during injection is independent of the plastic temperature. Failure during injection may occur either at low tool temperature when tool toughness is not sufficient, or at high tool temperature (above epoxy T g ). As experience and theoretical calculations confirm, flexural stresses during the injection process are the most probable cause of failure. Reducing the features aspect ratio of tool decreases the chances of flexural failure. shear stress at 1/4 fron N.A. shear stress at N.A. 11.71 MPa 13.18 MPa 17.57 MPa 13.18 MPa across the largest cube base. 6070 809010 0 10 20 30 40 50 60 70 80 90 100 110 120 Temperature (Deg C) Pressure Temperature time during injection cycle. C15 Shear stress failure during injection is less likely than flexural failure in particular when the SL tool is warmed to over 401C prior to injection. References 1 D. Chen, F. Cheng, Integration of product and process development using rapid prototyping and work cell simulation technology, Journal of Industrial Technology 16 (1) (2000). 2 J.A. McDonald, C.J. Ryall, D.H. Wimpenny, Rapid Prototyping Casebook, Professional Engineering Publishing, UK, 2001. 3 M.A. Evans, R.I. Campbell, A comparative evaluation of industrial design models produced using rapid prototyping and workshop- based fabrication techniques, Rapid Prototyping Journal 9 (5) (2003). 4 A. Venus, S. Crommert, Manufacturing of Injection Molds with SLS Rapid Tooling, Rapid Prototyping, vol. 2 (2), Dearborn, USA, 1996. 5 Y. Li, M. Keefe, E.P. Gargiulo, Studies in Direct Tooling by Stereolithography, Sixth European Conference on Rapid Prototyping and Manufacturing, Nottingham, UK, July 1997, ISBN:0-9519759-7- 8, pp. 253266. 6 P. Decelles, M. Barritt, Direct AIM Prototype Tooling, 3D Systems, 1996 P/N 70275/11-25-96. 7 T. Greaves, (Delphi-GM), Case study: using stereolithography to directly develop rapid injection mold tooling, TCT Conference, 1997. 8 P. Jacobs, Recent Advances in Rapid Tooling From Stereolitho- graphy, A Rapid Prototyping Conference, Oct. University of Maryland, USA, 1996. 9 S. Rahmati, P.M. Dickens, Stereolithography injection moulding tooling, Sixth European Conference on Rapid Prototyping and Manufacturing, Nottingham, UK, ISBN:0-9519759-7-8, 1997, pp. 213224. 10 S. Rahmati, P.M. Dickens, Stereolithography injection mould tool failure analysis, Eighth Annual Solid Freeform Fabrication, Texas, 1997, pp. 295305. 11 S. Rahmati, P.M. Dickens, C. Wykes, Pressure effects in stereo- lithography injection moulding tools, Seventh European Conference on Rapid Prototyping and Manufacturing, Aachen, Germany, 1998, pp. 471480. 12 G. Menges, P. Mohren, How to make injection molds, Hanser, Munich, ISBN:0-02-947570-8, 1986. 13 G.C. Ives, J.A. Mead, M.M. Riley, in: R.P. Brown (Ed.),Handbook of Plastics Test Methods, second ed, London, ISBN:0-7114-5618-6, 1981. 14 R.A. Douglas, Introduction to Solid Mechanics, Sir Isaac Pitman & Sons Ltd., London, 1989. 15 R.W. Hertzberg, J.A. Manson, Fatigue of Engineering Plastics, Academic, New York, 1980. 17 J.W. Dally, F.R. William, Experimental Stress Analysis, 3rd ed, McGraw-Hill, ISBN 0-07-015218-7, 1991. 18 F. Cheng, Statistics and Strength of Materials, 2nd ed, McGraw-Hill, ISBN 0-07-115666-6, 1997. ARTICLE IN PRESS S. Rahmati, P. Dickens / International Journal of Machine Tools & Manufacture 47 (2007) 740747 747 畢業(yè)設(shè)計(論文)外文資料翻譯 系 別 電信息系系 專 業(yè) 機械設(shè)計制造及其自動化 班 級 B070203 姓 名 李 勇 學(xué) 號 B0706011 外文出處 ScienceDirect International Journal of Machine Tools & Manufacture 47 (2007) 740–747 附 件 1. 原文； 2. 譯文 分析快速成型注塑模具加工程序 Sadegh Rahmati, Phill Dickens 摘要 隨著全球市場競爭的日益激烈，企業(yè)壓力增加，不斷調(diào)低產(chǎn)品生產(chǎn)周期。由于交貨時間和工具加工成本趨于下降的趨勢,所以現(xiàn)代工具制造廠必須在壓力下快速、準(zhǔn)確、以較低成本來生產(chǎn)產(chǎn)品?？s短生產(chǎn)原型產(chǎn)品是時間加快新產(chǎn)品開發(fā)的關(guān)鍵?？焖俪尚湍＞呱a(chǎn)當(dāng)中，特別使用快速成型技術(shù)制造注塑模具裝配可節(jié)約生產(chǎn)成本并減少時間。在本文中,快速成型技術(shù)是用來直接生產(chǎn)快速注射模這種短期生產(chǎn)工具。對快速成形工具成功注射的數(shù)量及其性能進行評價分析。快速成型環(huán)氧工具能抵抗注射壓力、注射溫度以及500次注射次數(shù)。對注射過程中工具失效機制調(diào)查得知工具的失效是由于過度的彎曲應(yīng)力或是因為由于剪切應(yīng)力過大而造成的。 2006年愛思唯爾出版社有限公司版權(quán)所有。 介紹 設(shè)計降低生產(chǎn)新部件時間的方法,因為產(chǎn)品的交貨時間拖很久的話無法滿足客戶需求[1,2]。設(shè)計能力提高、產(chǎn)品品種增加、交貨時間縮短，以及產(chǎn)量降低，均是快速模具技術(shù)發(fā)展的重要驅(qū)動力,生產(chǎn)期間，加工時間和生產(chǎn)成本明顯有所降低[3 - 5]。與此同時,快速成型模具加工技術(shù)正在不斷提高,并在制造商企業(yè)內(nèi)越來越受歡迎 [6 - 8]。在諾丁漢大學(xué)研發(fā)的快速成型注塑模具工具方面占有兩種優(yōu)勢。 第一種是在在應(yīng)力和溫度的極端條件下針對工具的設(shè)計可提供資料數(shù)據(jù),并能從不同的測試中獲取數(shù)據(jù), 類似于真實情況[9]。第二種是研發(fā)一種理論分析快速成型注塑模具過程的方法 [10]。這證明可使用少量的快速成型注塑模具成功生產(chǎn)五百個以上數(shù)量的工具零件。 作者：S. Rahmati的郵箱，rahmati@rapidtoolpart.com。英國拉夫堡大學(xué)快速生產(chǎn)研究小組的負(fù)責(zé)人和教授。 實驗方法 在構(gòu)建快速成型注塑模具工具過程當(dāng)中，根據(jù)光固化快速成型250型號快速成型機上的CAD數(shù)據(jù)，直接將環(huán)氧樹脂殼層嵌入到模具當(dāng)中。這些嵌入物正好通過鋼框架插入到鋼模具當(dāng)中，模具背面用鋁粉或是鋁薄片和環(huán)氧樹脂的混合物填充(圖1)。這些混合物額外增加了嵌入物力量并使模具具有散熱特點。使用50噸的巴頓菲爾注塑機測試快速成型工具，生產(chǎn)聚丙烯和丙烯腈丁二烯苯乙烯零件。如圖2 彈簧澆注系統(tǒng) 快速成型模具 上內(nèi)模 腔鋼框架 模后填充材料 鐵心用鋼框架 頂出 針 快速成型模具下內(nèi)膜 圖1：快速成型模具工具鑲件橫截面 圖2：從快速成型工具取出后的模具狀態(tài) 模具加工過程當(dāng)中，測出型腔模具溫度和壓力，利用不同的熱電偶控制熔體溫度，以盡可能地確保型腔狀態(tài)保持一致。使用光學(xué)顯微鏡或是掃描電子顯微鏡檢測兩種模具斷裂樣本。裂縫的立方體用于橫截面和斷裂面的研究。裂縫當(dāng)中嵌入模具材料的立方體，使用鑄造材料鑄好，切割然后使用光學(xué)顯微鏡將其拋光，以便于檢測?？墒?，使用掃描電子顯微鏡研究立方體斷裂面和模心，導(dǎo)致快速成型模具工具出現(xiàn)失效機理。 注射壓力分析 在噴射器底部放上測壓軟件來檢測壓力剖面（如圖3）。 澆道套 模制 澆鑄道 噴射器內(nèi)角 模腔邊 噴射器中間 噴射器 測壓元件 模蕊側(cè)  噴射器中間 測壓元件電纜 圖3：噴射器和測壓元件的位置 在頂針施加的壓力將轉(zhuǎn)移到放置在噴射器另一末端的測壓元件上。取五個頂針其中的三個,其中一放在噴射器中間，另外兩個放在噴射器拐角處，測量壓力。所有的測壓元件與數(shù)據(jù)記錄器連接，并用電腦操作。在注射過程中記錄的變化電壓轉(zhuǎn)換成為壓力。結(jié)果如圖4描繪所示，在噴射器中間達到最大噴射壓力1650 psi （11.4兆帕), 在噴射器拐角壓力下降到約1300psi(9兆帕)。 1800 1600 1400 1200 1000 800 600 400 200 0 快速成形環(huán)氧樹脂模具型腔三個地方的壓力剖面 Corner Pressure 1 Middle Pressure Corner Pressure 3 0 3 6 9 12 15 18 21 24 時間 (秒) 圖4. 快速成形環(huán)氧樹脂模具型腔三個地方的壓力剖面。 快速成型環(huán)氧樹脂模具工具相關(guān)溫度和材料的研究 圖5記錄了在周期時間內(nèi)的典型實際溫度，在開始下一次注射前，溫度達到451攝氏足夠在規(guī)定時間內(nèi)完成使模具冷卻過程。為了計算抗?jié)q強度和剪切應(yīng)力，需準(zhǔn)備標(biāo)準(zhǔn)實驗樣品，規(guī)格按照ISO527測量剪切應(yīng)力，按照ISO179檢測沖擊強度。 120 100 80 60 40  模心1 模心2 模心3 模心4 型腔1 型腔2 型腔3 型腔4 20 0 0 100 200 300 400 500 600 時間 秒) 圖5：環(huán)氧樹脂模具工具內(nèi)逐次循環(huán)溫度變化 沖擊強度平均值被測定為28.4 kJ/m2 ，不同溫度平均值如圖6描繪所示。環(huán)氧樹脂拉力和剪切力測試結(jié)果如圖7所示。 100 90 沖擊強度 80 70 60 50 40 30 20 10 20 30 40 50 60 70 80 90 溫度 (攝氏度) 圖6：飽和環(huán)氧樹脂的不同溫度下相關(guān)的沖擊強度。 70 70 60 60 抗拉強度(MPa) 50 剪切應(yīng)力(MPa) 50 40 40 30 30 20 20 10 10 0 0 10 20 30 40 50 60 70 80 90 100 110 溫度 (°C) 圖7：快速成型環(huán)氧樹脂5170型號模具的相關(guān)溫度下的最大抗拉強度和最大剪切應(yīng)力 失效機理分析 當(dāng)塑膠被注入到在型腔時,型腔內(nèi)突然壓力上升, 在成型周期期間內(nèi)腔壓力達到最高(圖4)。這種壓力表現(xiàn)出核心特征,這可能導(dǎo)致工具斷裂,如果超過材料的極限抗拉強度極限抗撓曲強度，圖8顯示了在注塑期間各種可能發(fā)生的情況,。在8(a),沒有失敗,8(b)中出現(xiàn)一個彎曲故障，8(c)有一個剪切破壞。瞬間彎曲應(yīng)力會導(dǎo)致過程失敗,或是裂紋擴展，疲勞失效。 立方體 模制 流動方向 旋轉(zhuǎn)點 熔體壓力傳感器 熔體壓力傳感器 (a) (b) (c) 圖8：注射期間發(fā)生不同情況下示意圖，(a) 沒有失敗; (b) 玩去破壞; (c) 剪切失敗. 在注射過程中抗彎失敗 觀察到絕大多數(shù)失敗的情況是在彎曲應(yīng)力上。出現(xiàn)彎曲故障時注射壓力克服了工具的抗彎強度,致使繞軸點旋轉(zhuǎn),最終導(dǎo)致斷裂(圖8(b))。如果注射壓力超出了快速成型模具工具的抗彎強度這種情況可能會出現(xiàn),但通?？箯澥∈怯捎谑褂么螖?shù)過多 (圖9)。表1記錄了快速成型模具立方體的抗彎強度的相關(guān)理論計算。 Z Y X軸方向的彎曲應(yīng)力 X a h Y Y 中性軸 塑性流動 圖9立方體壓力參量和迎風(fēng)氣流示意圖 表 1 快速成型模具立方體彎曲應(yīng)力 慣性矩 力矩 彎曲應(yīng)力 40 1攝氏度 撓曲強度 （m4) (N m) (Mpa) (Mpa) 立方體1 108 x 10—12 1.687 46.85 65.0 然而,在實踐當(dāng)中,產(chǎn)生了數(shù)以百計的快速成型模具工具零件失效情況,過高地估計理論模型的彎曲應(yīng)力。這兩個理由，第一，最小寬高比為10時彎曲應(yīng)力方可承擔(dān),而實驗當(dāng)中高寬比為四。第二, 在注射過程中注射壓力施加應(yīng)該在在立方體的前面,但是現(xiàn)實中這種壓力施加在熔壓方塊的后面。 疲勞裂紋擴展 圖10是一幅拍攝在實際故障發(fā)生前的制模斷面圖，圖中顯示的是在后續(xù)注射制模時真實的逆裂紋方向，也就是裂紋產(chǎn)生的相反方向。圖11顯示了一個簡單的立方體的抗彎失敗圖,而圖10是經(jīng)過大量的鏡頭拍攝得到的。在快速成型模具工具在設(shè)置應(yīng)力集中時發(fā)生裂紋萌生,如尖銳的角度和階梯(此為快速成型模具工具零件固有性質(zhì))。 圖10：制模過程失敗前產(chǎn)生的多余的裂紋 圖11：抗彎失敗后裂紋擴展圖 裂縫破壞的跡象如圖12所示,能看到在破裂面條紋形式排列,每條裂紋都代表裂紋擴展?fàn)顟B(tài)。 圖12 掃描式電子顯微鏡下觀察到的斷裂面上的真實條紋 剪切破壞 剪切破壞在熔體流動的方向剪切時出現(xiàn)。圖13展示了快速成型模具立方體的剪切斷面圖。值得注意的是,快速成形模具立方體是通過塑料流動堆積而成的表2記錄了剪切應(yīng)力的計算結(jié)果, 在操作期間產(chǎn)生快速成型工具的最大剪切應(yīng)力，均低于快速成型工具工具的抗剪強度。此外, 在表2最后一列所示注射溫度超過401攝氏度時快速成型工具可以被制做成功。圖14,描繪立方體各點最大剪切應(yīng)力的剪切應(yīng)力與平均剪切應(yīng)力比較，以及最大剪切應(yīng)力各點拋物曲線情形。 表 2 快速成型模具立方體個點剪切應(yīng)力 剪切面積 AS (mm2) 剪切力 V (N) 剪切應(yīng)力 tave (Mpa) 剪切強度（40 1攝氏度） (Mpa) 最高溫度 (1C) 立方體1 36 421.64 11.71 24.3 65.3 立方體2 2 30 421.64 14.05 24.3 61.5 立方體3 3 24 421.64 17.57 24.3 55.9 立方體4 18 421.64 23.42 24.3 46.4 ? ? N.A. 圖14：最大立方體底部剪切壓力分布圖 結(jié)論 該技術(shù)成功的關(guān)鍵是快速成形工具必須有極低的導(dǎo)熱系數(shù)和較短的注射時間 (圖15)。這兩個因素是快速成型注塑模具成功的關(guān)鍵, 可大多情況下都被忽略了。 圖15：注射期間壓力與溫度相關(guān)分布圖 工作的結(jié)果可歸納如下: ?使用環(huán)氧樹脂過以生產(chǎn)超500個零件，并且使用外間空氣冷卻型腔到451攝氏度。 ?在注射過程中工具的失效歸因于塑料溫度。 ?在注射過程中在工具韌性不好,或在工具溫度過高時可能會出現(xiàn)失敗。 ?經(jīng)驗和理論計算確認(rèn),在注射過程中大多是由于抗彎曲應(yīng)力失效而失敗。減少了長寬比的特征會降低工具抗彎曲失敗的現(xiàn)象。 ?在注射過程中很少可能由于彎曲破壞而導(dǎo)致剪切應(yīng)力失效，由于快速成形工具要求特定條件，溫度超過401攝氏度才能注射。 參考文獻 1. [1] D. Chen, F. Cheng，《工業(yè)技術(shù)一體化的產(chǎn)品和工藝開發(fā)過程使用快速成型和工作細(xì)胞仿真技術(shù)雜志》16(1)(2000)。 2. J.A. McDonald, C.J. Ryall, D.H. Wimpenny快速原型個案資料，專業(yè)工程出版，英國，2001。 3. M.A. Evans, R.I. Campbell，使用快速成型模型比較評估工業(yè)設(shè)計和加工技術(shù)研討會，快速樣機成型雜志 9（5）（2003） 4. A. Venus, S. Crommert,快速成型注塑模具工業(yè)生產(chǎn)，快速原型法，容積2（2）。美國迪爾伯恩市1996。 5. Y. Li, M. Keefe, E.P. Gargiulo,研究直接加工快速成型模具工具，第六快速成形制造方法歐洲會議，諾丁漢,英國,1997年7月,ISBN:0-9519759-7-8，頁數(shù)：253-266。 6. P. Decelles, M. Barritt, AIM原型工具,三維系統(tǒng),1996年P(guān) / N 70275/11-25-96。 7. T. Greaves, (Delphi-GM),研究:利用快速成型技術(shù)發(fā)展注塑模制模工具，生產(chǎn)廠家會議,1997年。 8. P. Jacobs,快速成型模具進展,快速成型會議，10月，美國馬里蘭大學(xué),1996年。 9. S. Rahmati, P.M. Dickens,快速成型注塑模具工具,第六個快速成形及其制造方面的歐洲會議，諾丁漢,英國,ISBN:0-9519759-7-8,1997年,第213-224頁。 10. S. Rahmati, P.M. Dickens,注塑模具的失效分析,第八年度固體成形技術(shù),德克薩斯州,1997年,頁數(shù)295-305。