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注塑模CAE技術(shù)
0引言
塑料產(chǎn)品從產(chǎn)品設(shè)計到成型生產(chǎn)包括塑料制品設(shè)計、模具設(shè)計、模具制造和注塑工藝參數(shù)選擇等幾個主要方面。傳統(tǒng)的注塑模具設(shè)計主要依靠設(shè)計人員的經(jīng)驗，而注塑成型過程非常復(fù)雜，塑料熔體的流動性能千差萬別，制品和模具的結(jié)構(gòu)千變?nèi)f化，工藝條件各不相同，成型缺陷各式各樣，模具設(shè)計往往需要反復(fù)的試模、修模才能投入生產(chǎn)，很少有一次成功的，發(fā)現(xiàn)問題后，不僅要重新調(diào)整工藝參數(shù)，甚至要修改塑料制品和模具，不但費時費力，而且降低了產(chǎn)品的開發(fā)速度。而利用注塑模CAE技術(shù)可以在模具制造前，模擬注塑過程（包括充填、保壓及冷卻）并及早發(fā)現(xiàn)問題，優(yōu)化模具設(shè)計和工藝條件設(shè)定，減少試模次數(shù)以提高生產(chǎn)效率，現(xiàn)已成為注塑加工技術(shù)的一個重要發(fā)展方向。
1注塑模CAE技術(shù)的歷史
注塑模CAE技術(shù)是根據(jù)塑料加工流變學(xué)和傳熱學(xué)的基本理論，建立熔體在模具型腔中的流動、傳熱的物理、數(shù)學(xué)模型，利用數(shù)值計算理論構(gòu)造其求解方法，利用計算機可視化技術(shù)形象、直觀地模擬出實際成型中熔體的動態(tài)填充、冷卻過程的一門分析技術(shù)。
20世紀(jì)60年代，英國、美國和加拿大等國的學(xué)者如J.R.Pearson(英)、J.F.Stevenson（美）、M.R.Kamal(加)和K.K.Wang(美)等開展了一系列有關(guān)塑料熔體在模具型腔內(nèi)流動與冷卻的基礎(chǔ)研究。在合理的簡化基礎(chǔ)上，60年代完成了一維流動與冷卻分析程序，70年代完成了二維冷卻分析程序，80年代注塑模CAE技術(shù)開始從理論研究進入實用化階段，開展了三維流動與冷卻分析并把研究擴展到保壓、纖維分子取向以及翹曲預(yù)測等領(lǐng)域。進入90年代后開展了流動、保壓、冷卻和應(yīng)力分析等注塑工藝全過程的集成化研究。
CAE技術(shù)的出現(xiàn)，為注塑模設(shè)計提供了可靠的保證，它的應(yīng)用是模具設(shè)計史上的一次重大變革。
2注塑模CAE技術(shù)的作用
利用傳統(tǒng)方法設(shè)計注塑模具，設(shè)計成功與否將很大程度上依賴設(shè)計者的經(jīng)驗，而且對復(fù)雜零件澆口位置的合理與否，排氣槽位置的設(shè)置、熔接線位置的確定等都十分困難。模具在交付使用之前一般需經(jīng)過反復(fù)試模修改，直到得到合格的制品為止，從而不可避免地造成了生產(chǎn)周期的延長，而且一般也難以得到最優(yōu)的設(shè)計方案和工藝參數(shù)。而利用注塑模CAE技術(shù)設(shè)計模具則不然，由于在模具設(shè)計構(gòu)思階段，可利用注塑模CAE 技術(shù)進行流動過程模擬，使得通常只有在模具試模階段才能發(fā)現(xiàn)的問題，如短射，熔接線或氣孔出現(xiàn)在外觀零件表面等問題得以避免。同時幫助設(shè)計人員完成諸如流道系統(tǒng)的平衡設(shè)計，排氣槽的設(shè)置，合理確定注塑工藝參數(shù)等工作，這樣使得通常在必須反復(fù)試模修改而確定的模具結(jié)構(gòu)參數(shù)和工藝參數(shù)在模具設(shè)計構(gòu)思階段得以確定，縮短了模具設(shè)計制造周期、提高了模具設(shè)計質(zhì)量。
所以注塑模CAE軟件的作用主要表現(xiàn)為：
（1）優(yōu)化塑料制品設(shè)計
塑料的壁厚、澆口的數(shù)量及位置、流道系統(tǒng)的設(shè)計等對于塑料制品的質(zhì)量有重大影響。以往全憑設(shè)計者的經(jīng)驗，用手工方法實現(xiàn)，費時費力，而利用CAE技術(shù)，可快速設(shè)計出最佳的制品。
（2）優(yōu)化塑料模具設(shè)計
可以對型腔尺寸、澆口位置及數(shù)量、流道尺寸和冷卻系統(tǒng)等進行優(yōu)化設(shè)計。在計算機上模擬試模、修模和提高模具質(zhì)量，減少實際試模次數(shù)。
（3）優(yōu)化注射工藝參數(shù)
對注射過程進行模擬，發(fā)現(xiàn)可能出現(xiàn)的成型缺陷，確定最佳的注射壓力、鎖模力、模具溫度、熔體溫度、注射時間和冷卻時間等。
由此可見，注塑模CAE技術(shù)無論在提高生產(chǎn)率、縮短模具設(shè)計制造周期和保證產(chǎn)品質(zhì)量，還是在降低成本、減輕勞動強度等方面，都具有很大的優(yōu)越性和重大的技術(shù)經(jīng)濟意義。
3注塑模CAE軟件種類及其簡介
到目前為止，成熟的商業(yè)注塑模CAE軟件比較多，Moldflow公司的Moldflow軟件和AC-Tech公司（2000年2月，被Moldflow公司合并）的C-Mold軟件是其中的優(yōu)秀代表；另外還有國外的TMCONCEPT、CADMold、Fidap、Stirm100、Polyflow和我國臺灣地區(qū)的Moldex等軟件應(yīng)用也比較廣；而國內(nèi)在“八五”期間才開始這方面的研究，現(xiàn)在華中理工大學(xué)的HSCAE軟件和鄭州大學(xué)的Z-Mold軟件在國內(nèi)處于領(lǐng)先地位。
Moldflow軟件是專業(yè)從事注塑成型CAE軟件和咨詢的Moldflow公司的系列產(chǎn)品，該公司自1976年發(fā)行了世界上第一套注塑模CAE軟件以來，一直主導(dǎo)注塑模CAE軟件市場。至2004年，Moldflow軟件在全球注塑模CAE市場的占有率達75%。
MoldFlow軟件包括三部分：MoldFlow Plastics Advisers（產(chǎn)品優(yōu)化顧問，MPA）、 MoldFlow Plastics Insisht（注塑成型模擬分析，MPI）和 MoldFlow Plastics Xpert（注塑成型過程控制專家，MPX）。
一般情況下，最常用MPI，主要用來對注塑過程進行模擬，從而得到最佳的澆口數(shù)量與位置，合理的流道系統(tǒng)與冷卻系統(tǒng)，并對型腔尺寸、澆口尺寸、流道尺寸和冷卻系統(tǒng)尺寸進行優(yōu)化，并且還可對注塑工藝參數(shù)進行優(yōu)化。
Moldflow軟件的模流分析技術(shù)可以分為三種，即Midplane、Fusion和3D。
4 Moldflow的Midplane分析技術(shù)
Midplane（中面流）的應(yīng)用始于20世紀(jì)80年代。其網(wǎng)格是三節(jié)點的三角形單元，其原理是將3D幾何模型簡化成中性面幾何模型（即將網(wǎng)格創(chuàng)建在模型壁厚的中間處），利用所建立的中性面進行模擬分析，即以平面流動來仿真三維實體流動。此分析技術(shù)發(fā)展至今已相當(dāng)成熟穩(wěn)定，其優(yōu)點為分析速度快、效率高。
基于中面流技術(shù)的注塑流動模擬軟件應(yīng)用的時間最長、范圍也最廣。但是實踐表明，基于中面流技術(shù)的模擬軟件在應(yīng)用中具有很大的局限性，具體表現(xiàn)為： (1) 用戶必須構(gòu)造出中面模型。采用手工操作直接由實體模型構(gòu)造中面模型十分困難，往往需要花費大量的時間，而且不能從其他CAD模型轉(zhuǎn)換。
(2) 無法描述一些三維特征。如不能描述慣性效應(yīng)、重力效應(yīng)對熔體流動的影響，不能預(yù)測噴射現(xiàn)象、熔體前沿的泉涌現(xiàn)象等。
(3) 由于CAD階段使用的產(chǎn)品模型和CAE階段使用的分析模型不統(tǒng)一，使二次建模不可避免，CAD與CAE系統(tǒng)的集成也無法實現(xiàn)。
5 Moldflow的Fusion分析技術(shù)
Fusion（雙面流）分析技術(shù)是基于Moldflow的獨家專利Dual Domain的分析技術(shù)。2000年推出的Fusion分析技術(shù)，使得用戶不需要抽取中性面就可以進行分析，克服了幾何模型的重建問題，大大減輕了用戶建模的負(fù)擔(dān)。網(wǎng)格也是三角形單元，而其原理是將模具型腔或制品在厚度方向上分成兩部分，有限元網(wǎng)格在型腔或制品的表面產(chǎn)生。在流動過程中，上、下兩表面的塑料熔體同時并且協(xié)調(diào)地流動。
顯然，F(xiàn)usion技術(shù)的表面網(wǎng)格是基于中性面的，仍無法解決中性面的根本問題，所以雙面流技術(shù)所應(yīng)用的原理和方法與中面流所應(yīng)用的沒有本質(zhì)上的差別，所不同的是雙面流采用了一系列相關(guān)的算法，將沿中面流動的單股熔體演變?yōu)檠厣?、下表面協(xié)調(diào)流動的雙股流。
雙面流技術(shù)的最大優(yōu)點是模型的準(zhǔn)備時間大大縮短，這樣就大大減輕了用戶建模的負(fù)擔(dān)，將原來需要幾小時甚至幾天的建模工作縮短為幾分鐘。因此，基于雙面流技術(shù)的模擬軟件問世時間雖然只有短短數(shù)年，但在全世界卻擁有了龐大的用戶群，得到了廣大用戶的支持和好評。
但是雙面流技術(shù)有以下不足：
(1) 由于雙面流技術(shù)沒有從根本上解決中性面的問題，所以還是無法描述某些三維特征，如不能描述慣性效應(yīng)、重力效應(yīng)對熔體流動的影響，不能預(yù)測噴射現(xiàn)象、熔體前沿的泉涌現(xiàn)象等。
(2) 上、下對應(yīng)表面的熔體流動前沿存在差別。由于上、下表面的網(wǎng)格無法一一對應(yīng)，而且網(wǎng)格形狀、方位與大小也不可能完全對稱，所以如何將上、下對應(yīng)表面的熔體流動前沿的差別控制在所允許的范圍內(nèi)是實施雙面流技術(shù)的難點。
(3) 熔體僅沿著上、下表面流動，在厚度方向上未作任何處理，缺乏真實感。
6 Moldflow的3D分析技術(shù)
以上兩種技術(shù)都忽略了厚度方向的物理量，只是二維的模擬，因而結(jié)果不是十分精確。Moldflow公司的3D（三維）分析技術(shù)采用了真三維實體模流分析技術(shù)，經(jīng)過嚴(yán)謹(jǐn)?shù)睦碚撏茖?dǎo)與反復(fù)的驗證，將慣性效應(yīng)、非恒溫流體等因素考慮到有限元分析中，熔體厚度方向的物理量變化不再被忽略，能夠更全面地描述填充過程的流動現(xiàn)象，使分析結(jié)果更能接近現(xiàn)實狀況，適用于所有塑件制品。其立體網(wǎng)格是由四節(jié)點的四面體單元組成。并采用全新的3D立體顯示技術(shù)，可快速清楚地顯示出模型內(nèi)、外部的流動場、溫度場、應(yīng)力場和速度場等分析結(jié)果。對于上述分析結(jié)果也可利用等位線或等位面方式顯示，讓實體模型內(nèi)、外部各變量的變化情形顯示更清楚，Moldfiow還提供動畫的功能，透過3D動畫的方式顯示塑料熔體在型腔中的流動變化，讓用戶更直觀地看清設(shè)計與制造過程中可能遇到的問題。
但是3D技術(shù)的網(wǎng)格劃分要求很高，控制方程更加復(fù)雜，計算量大、時間長，計算效率低，不適合開發(fā)周期短并需要通過CAE進行反復(fù)修改驗證的注塑模設(shè)計。因此，目前該技術(shù)普及率不是很高，不過它最終必將取代中面流技術(shù)和雙面流技術(shù)。
7注塑模發(fā)展趨勢
注塑模CAE技術(shù)不論從理論上還是在應(yīng)用上都取得了長足的進步，但在以下幾個方面仍有待于進一步完善和發(fā)展：
（1）數(shù)學(xué)模型、數(shù)值算法逐步完善
注塑模CAE技術(shù)的實用性，取決于數(shù)學(xué)模型的準(zhǔn)確性及數(shù)值算法的精確性。目前的商品化模擬軟件模型沒有完全考慮物理量在厚度方向上的影響，為了進一步提高軟件的分析精度和使用范圍，必須進一步完善目前的數(shù)學(xué)模型和算法。
（2）注塑成型全過程模擬
目前，注塑成型模擬軟件主要有填充、流動、保壓、冷卻、應(yīng)力應(yīng)變和翹曲分析等模塊，各模塊的開發(fā)是基于各自獨立的數(shù)學(xué)模型，這些模型在很大程度上進行了簡化，忽略了相互之間的影響。但是，從注塑成型工藝過程來看，塑料熔體的填充、流動、保壓和冷卻是交織在一起并相互影響的，因此，填充、流動、保壓和冷卻分析模塊必須有機地結(jié)合起來，進行耦合分析，才能綜合反映注塑成型的真實情況。
（3）優(yōu)化理論及算法，使CAE技術(shù)“主動”地優(yōu)化設(shè)計
將人工智能技術(shù)，如專家系統(tǒng)和神經(jīng)網(wǎng)絡(luò)等加入設(shè)計計算中，使模擬程序能“智慧”地選擇注塑工藝參數(shù)、提供修正制品尺寸和冷卻管道布置方案，減少人工對程序的干涉。
（4）對新的注塑成型方法進行模擬分析
目前，在常規(guī)注塑成型技術(shù)的基礎(chǔ)上，又發(fā)展出了一些新的注塑成型方法，比如氣體輔助注射、薄壁注塑成型、反應(yīng)注射和共注射等。但是還沒有專門針對這些成型方法的模擬軟件，所以亟待開發(fā)。
（5）注塑模CAD/CAE/CAM的集成化與網(wǎng)絡(luò)化
目前的商品化注塑模CAE軟件與CAD、CAM軟件之間的數(shù)據(jù)傳遞主要依靠文件的轉(zhuǎn)換，這容易造成數(shù)據(jù)的丟失和錯誤。因此在設(shè)計制造過程中采取單一模型，建立注塑模CAD/CAE/CAM系統(tǒng)的統(tǒng)一數(shù)據(jù)庫，加強三者之間的聯(lián)系是今后的發(fā)展方向之一。為適應(yīng)電子商務(wù)的發(fā)展要求，這個集成系統(tǒng)將實現(xiàn)異地的“協(xié)同設(shè)計”和“虛擬制造”。
8結(jié)束語
盡管通過大量的實踐證明，在塑料模具工業(yè)中引入CAE技術(shù)后，大大縮短了模具設(shè)計和制造周期，提高了模具的使用壽命和制造精度。同時，CAE技術(shù)的出現(xiàn)也使注塑模設(shè)計從傳統(tǒng)的經(jīng)驗和技藝走上科學(xué)化的道路，在一定程度上改變了注塑模傳統(tǒng)的生產(chǎn)方式，但目前CAE技術(shù)并不能代替人的創(chuàng)造性工作，只能作為一種輔助工具幫助工程師了解方案中存在的問題，還難以提供一個明確的改進方案，仍需通過反復(fù)交互（分析－修改－再分析），才能將設(shè)計人員的正確經(jīng)驗體現(xiàn)到模具設(shè)計中去，而設(shè)計方案的確定很大程度上仍需依靠設(shè)計人員的經(jīng)驗和水平。
Injection Molding CAE Technology
0 Introduction
Plastic products from product design to production, including molding plastic products design, mold design, mold manufacturing and injection molding process parameters and several other main areas. The traditional injection mold design mainly rely on the designer's experience, while the injection molding process is very complex, plastic melt flow properties of different and ever-changing products and die structure, process conditions vary, forming various defects, mold design often require repeated trial-mode, maintenance mode can be put into production, with little of a successful, identify problems, not only to re-adjust the process parameters, or even to modify the plastic products and molds, not only time-consuming and laborious, but also reduces product development time . The use of injection molding CAE technology in mold manufacturing prior to simulate injection molding process (including filling, packing and cooling) and the early detection of problems, optimize mold design and process conditions set to reduce the number of test mode in order to improve production efficiency, has become a injection molding technology is an important direction of development.
1 The history of Injection Molding CAE technology
Injection Molding CAE technology is based on plastics processing rheology and heat transfer of the basic theory, the melt in the mold cavity in the flow, heat transfer physics, mathematical model, using numerical solution method of constructing the theory, the use of computer visualization technology image, visually simulate the dynamics of the actual shape of the melt filling and cooling process, an analysis techniques.
The 20th century, 60 years, the United Kingdom, the United States and Canada and other countries of the scholars, such as JRPearson (United Kingdom), JFStevenson (America), MRKamal (Canada) and KKWang (America), etc. to carry out a series of plastic melt in the mold-type cavity flow and cooling of basic research. At a reasonable simplification, based on 60 years completed a one-dimensional flow and cooling analysis programs, 70 years to complete the two-dimensional cooling analysis programs, and 80 years from the injection molding CAE technology has begun to theoretical research into the practical phase, launched a three-dimensional flow and cooling analysis and the study extended to packing, fiber orientation and warpage prediction of molecular and other fields. After 90 years carried out into the flow, packing, cooling and stress analysis, the whole process of injection molding processes are integrated research.
CAE technologies, for the injection mold design provides a reliable guarantee that its application is mold design in the history of a major change.
2 The role of Injection Molding CAE technology
Using traditional methods of design of injection mold design success will rely heavily on the experience of designers, but also for complex parts gate position is reasonable or not, the location of the exhaust slot settings, to determine the location of weld lines and so very difficult. Die in delivery will normally take before the test mode after repeated changes, until the products have been qualified, which inevitably led to the extension of the production cycle, and generally difficult to obtain an optimal design and process parameters. The use of injection molding CAE technical design, mold is not true, because of mold design concept stage, can make use of CAE technology in injection molding process simulation flow, making usually only in the mold tryout phases in order to find problems, such as short shots, weld lines or holes appear in the surface appearance of parts and other issues have been avoided. While helping the designer to complete the balance of the system, such as flow channel design, exhaust ducts, setting, rationally determine the injection molding process parameters, etc., so that usually makes the modification must be repeated tryout to determine structural parameters of the mold die design and process parameters in the conceptual stage able to determine, reduce the mold design and manufacturing cycle and improve the mold design quality.
Therefore, the role of injection molding CAE software, mainly as follows:
(1) Optimize design of plastic products
Plastic wall thickness, gate number and location of the design of flow channel system for the quality of plastic products have a significant impact. Depends on the experience of the past, designers using manual methods to achieve, time-consuming effort, but the use of CAE technology to quickly design the best products.
(2) optimize the plastic mold design
Can be cavity size, gate location and number of flow channel dimensions and cooling systems to optimize the design. On the computer simulation test mold, mold repair mold and improve quality and reduce the number of actual tryout.
(3) to optimize injection process parameters
Simulation of the injection process and found possible shape defects, to determine the best injection pressure, clamping force, mold temperature, melt temperature, injection time and cooling time.
This shows that the injection molding CAE technology in terms of improving productivity, reduce mold design and manufacture cycle and to ensure product quality, or reduce costs, reduce labor intensity and so on, have very significant technical advantages and economic significance.
3 Injection Molding CAE software types and their details
To date, a mature business are more injection molding CAE software, Moldflow Corporation Moldflow software and AC-Tech, Inc. (February 2000, was Moldflow Merger) and C-Mold software is an excellent representative; There are also foreign The TMCONCEPT, CADMold, Fidap, Stirm100, Polyflow and China's Taiwan region Moldex-peer software applications are relatively wide; and domestic in the "Eighth Five-Year" period began research in this area, and now Huazhong University of Technology HSCAE software and Zhengzhou University, Z -Mold software in China in the leading position.
Moldflow software is specialized in injection molding CAE software and consulting for Moldflow's range of products, the company issued since 1976, the world's first set of injection molding CAE software, has been a leading injection molding CAE software market. To 2004, Moldflow Injection Molding CAE software in the global market share of over 75%.
MoldFlow software includes three parts: MoldFlow Plastics Advisers (product optimization consultant, MPA), MoldFlow Plastics Insisht (injection molding simulation analysis, MPI), and MoldFlow Plastics Xpert (injection molding process control specialists, MPX).
Under normal circumstances, the most commonly used MPI, is mainly used for injection molding process simulation to get the best number and location of the gate, reasonable flow channel system and cooling system, and cavity size, gate size, runner size and cooling systems to optimize the size and the injection molding process parameters may also be optimized.
Moldflow Software Moldflow analysis techniques can be divided into three kinds, namely, Midplane, Fusion and 3D .
4 Moldflow analysis of Midplane
Midplane (in the surface flow) applications began in the 20th century, the 80s. The grid is a three-node triangular element, its principle is the 3D geometric model of simplified geometric model of the neutral surface (to be created in the model grid the middle of the wall thickness), using established simulation analysis of the neutral surface, ie to flow in plane to simulate three-dimensional solid flow. The analysis of technological development has been very mature and stable, and the advantages for the analysis of speed and high efficiency.
Based on the flow of surface flow simulation of injection molding technology, software applications, the longest, widest range. But the practice shows that, based on the surface flow simulation software in the application of technology that has significant limitations, specifically as follows:
(1) The user must construct a mid-surface model. Using manual directly from the physical model structure in the surface model is very difficult and often takes a lot of time and can not be converted from other CAD models.
(2) can not be described in a number of three-dimensional features. If they can not describe the inertia effect, gravitational effects on melt flow, which fail to predict jet phenomenon, melt the forefront of Quan phenomena.
(3) The use of CAD phase of the product model and stages of the use of CAE analysis model is not unified, so that the inevitable second modeling, CAD and CAE systems integration can not be achieved.
5 Moldflow's Fusion analysis
Fusion (double flow) analysis technique is based on Moldflow's patented Dual Domain of analysis techniques. Fusion launched in 2000, analysis techniques, enabling users do not need to extract the neutral surface can be analyzed, to overcome the reconstruction of the geometric model, thus greatly reducing the burden on the user modeling. Grid is also a triangular element, and its principle is to mold cavity or the products in the thickness direction is divided into two parts, finite element mesh on the surface of the cavity or the products. In the flow process, the upper and lower surface of the plastic melt at the same time two and to coordinate movement of the simulation shown .
Clearly, Fusion technology, the surface of the grid is based on the neutral surface is still not solve the fundamental problem the neutral surface, so double-sided application of the principle of streaming technologies and methods applied in the surface flow with no difference in the nature, the The difference is two-sided flow using a series of related algorithms, will flow along the surface of the single-stranded melts evolved along the upper and lower surface of the coordination of the flow of dual-stream.
Double-sided flow of technology's biggest advantage is that the model greatly shorten the preparation time, thus greatly reducing the burden on the user modeling, will take several hours or even days of the original modeling work reduced to a few minutes. Therefore, based on double-sided flow simulation software technology, although the advent of time, only a few years, but in the world but has a huge user base, get the majority of customers for their support and praise.
But the double-sided flow of technology has the following deficiencies:
(1) The two-sided flow of technology does not fundamentally resolve the issue of a neutral face, they still can not describe some three-dimensional features, such as the inertial effect can not describe gravity effect on the melt flow, which fail to predict jet phenomenon, melt cutting-edge Quanyong phenomena.
(2) the upper and lower surfaces corresponding to the melt flow front there are differences. As the upper and lower surface of the grid can not be one correspondence, but the grid shape, orientation and size can not be completely symmetrical, so how the upper and lower surfaces corresponding to the difference between the melt flow front control is within the scope permitted by Difficulties in the implementation of double-sided streaming technology.
(3) melt is only along the upper and lower surface flows, in the thickness direction is not to make any treatment, lack of realism.
6 Moldflow's 3D analysis techniques
These two techniques have overlooked the thickness direction of the physical quantity, only two-dimensional simulation, and therefore results are not very precise. Moldflow Corporation's 3D (3D) analysis technology uses a true three-dimensional solid model flow analysis techniques, through rigorous theoretical derivation and repeated verification, the inertial effect, non-isothermal flow, taking into account factors such as finite element analysis, the melt thickness direction of the physical quantity changes will no longer be ignored, can be a more comprehensive description of the process of filling flow phenomena, so that results of the analysis more realistic conditions, applicable to all plastic products. Its three-dimensional grid is from the four-node tetrahedron unit. And using the new 3D stereoscopic display technology, can quickly model clearly shows that internal and external flow field, temperature field, stress field and velocity field such as analysis results. For the above-mentioned results of the analysis can also be used such as bit lines or equipotential surface display, so that physical models and external changes in the variables show more clearly the case, Moldfiow also offers animation capabilities, through 3D animation display plastic melt in the changes in the flow cavity, allowing users to more intuitively see the design and manufacturing process may encounter problems.
But the 3D technology, meshing demanding, more complex equations to calculate the amount of large, long duration and the computational efficiency is low, not suitable for short development cycle and need to be repeatedly revised by CAE verification injection mold design. Therefore, the current penetration rate of the technology is not very high, but it will eventually replace the surface flow of technology and double-sided streaming technology.
7 Development Trend of Injection Molding
Injection Molding CAE technology, whether in theory or in the application have made great strides, but in the following still needs further improvement and development :
(1) mathematical models, numerical algorithms to gradually improve the
Injection Molding CAE technology, practicality, depending on the accuracy of the mathematical model and numerical algorithm accuracy. The current commercial simulation software models do not fully consider the physical quantities in the thickness direction of the impact of the software in order to further improve the analysis accuracy and scope to further improve the existing mathematical models and algorithms.
(2) the whole process of injection molding simulation
At present, the injection molding simulation software are mainly filling, flow, packing, cooling, stress and strain and warpage analysis modules, each module was developed based on independent mathematical models, these models has been simplified to a large extent, ignored of the mutual effects. However, in view of injection molding process, plastic melt filling, flow, packing and cooling are intertwined and affect each other and, therefore, filling, flow, packing and cooling analysis module must be organically combined to carry out coupling analysis, in order to comprehensively reflect the real situation of injection molding.
(3) optimization theory and algorithms, so that CAE technology "active" to optimize the design
Artificial intelligence technologies, such as expert systems and neural networks on the design calculations, so that simulation can "wisdom" to choose the injection molding process parameters, product size and cooling to fix the piping layout programs to reduce manual intervention in the program.
(4) a new method of injection molding simulation analysis of the current
In the conventional injection molding technology, based on and the development of a number of new injection molding methods, such as gas-assisted injection, thin wall injection molding, reaction injection and co-injection . However, no specific methods for these molding simulation software, so untapped.
(5) injection mold CAD / CAE / CAM integrated and network-based
The current commercial injection molding CAE software and CAD, CAM software, data transfer between the mainly rely on the file conversion, which easily lead to data loss and errors. Therefore, in design and manufacturing process to take a single model, the establishment of injection mold CAD / CAE / CAM system, a unified database to strengthen the linkages between the three directions of future development. In order to meet the development requirements of e-commerce, this integrated system will achieve different places of the "Collaborative Design" and "virtual manufacturing."
8 Conclusion
Despite the adoption of a large number of practice has proved, in the plastic mold industry, the introduction of CAE technology, greatly reducing the mold design and manufacturing cycle and improve the life of the mold and manufacturing precision. At the same time, CAE technologies has also made from the traditional injection mold design experience and skills onto the road of scientific, to a certain extent, changed the injection mold of traditional production methods, but there is no substitute for CAE technology and people's creative work, only can serve as a complementary tool to help engineers understand the problems in the program, but also difficult to provide a clear improvement program, still need to through repeated interactions (analysis - changes - re-analysis) in order to reflect the experience of the designer's right to die design go, the program is designed to determine to a large extent continue to rely on the designer's experience and level.
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