外文翻譯---帶自由面壓鑄模具冷卻系統(tǒng)的最優(yōu)設(shè)計(jì)

1、<p><b>　　附 錄</b></p><p>　　The Optimal Design of a Cooling System for a Die-Casting Die With a Free Form Surface</p><p><b>　　Abstract</b></p><p>　　This s

2、tudy is on the finite element and abductive network method application to die-casting dies with free-form surfaces.The study aims to find the optimal cooling system parametersand decrease in deformation of a die-casting

3、die. In order to avoid the numerous influencing factors, the free-form surface of a die-casting die is created as a non-linear Eq. of a polynomial function. The parameters of the cooling system, including the channel spa

4、ce and channel diameter, are adjusted according to the</p><p>　　An abductive network has been built for modelling the diecasting cooling parameters. The abductive network is composed of a number of functiona

5、l nodes. Once the cooling system parameters are given, this network can predict the deformation of the die-casting accurately. A simulated annealing optimization algorithm with a performance index is then applied to the

6、neural network for searching for the optimal cooling system parameters and to obtain a satisfactory result.</p><p>　　Keywords： Die-casting die；Free-form；Neural network；Simulated annealing</p><p>

7、;　　1. Introduction</p><p>　　The typical, traditional die-casting process includes high-pressure filling, cooling, solidification and ejection stages. The cooling stage is of great importance because it signi

8、ficantly affects both the productivity and the quality of the die-cast part. It is well known that about 80% of the cycle time of die-casting is spent in cooling the hot melt sufficiently so that the cast part can be eje

9、cted without warp. The design of a successful die can be considerably affected by perfect filling, wh</p><p>　　(1) achieving uniform temperature and. </p><p>　　(2) mini-mising the cycle time.<

10、;/p><p>　　To achieve these two aims, the designer may need an optimal computer-aided design system to achieve a rapid and uniform cooling system. The design of an optimal system needs analysis of 3D heat transf

11、er during the filling and cooling processes.The thermal analysis tool should predict the temperature gradient and deformation of the die-body.</p><p>　　Generally speaking, traditional die design still depend

12、s on experience, due to the lack of analytic ability in mould flow and heat transfer, so the designer is unable to evaluate and handle the deformation resulting from material and thermal expansion and shrinkage of the di

13、e. The parameters of different cooling systems can cause large temperature gradients, and different deformations.</p><p>　　Although FEM software is capable of analysing the fillingflow and cooling conditions

14、 of pressure-injected metal and the heat stress, heat strain and temperature distribution conditions of a die-casting die under various cooling systems, the establishment of an analytic model is very difficult, especiall

15、y for 3D free-form geometry. Besides understanding the requirements of multi-cavity dies, and the metal flow and solidification process, the designer should be fully acquaintanted with the basic f</p><p>　　I

16、nitially, consider the design of the vent gate and overflow gate in the process of injection and flow to fill the die cavity during cold room die-casting as investigated by simulation by Garber [2]. When metal casting us

17、ing a plunger into a cavity,he considered the change occurring in the metal, and the replacement of the air in the cavity by molten metal. Subsequently, Garber [3,4] showed that too large or too small a plunger speed wil

18、l affect the cast quality. Groenevelt and Kaiser [5] studie</p><p>　　Jong et al. [9] developed a mathematical Eq. for the flow and solidification of molten metal during high-pressure diecasting, in order to

19、analyse the temperature conditions and solidification strain of die-cast components in the cavity.</p><p>　　Kenichiro et al. [10] used a finite element method to analyse and design the die; the result was no

20、t only improved accuracy, but the factors to be considered are increased too, and the pressure of die-casting, the speed of molten liquid flow, viscosity, and the mechanical nature of the material changed with temperatur

21、e and phase.</p><p>　　This study uses CAD\CAE error software for a systemic design process of a die, in order to minimise human error in die design [11–13]. It uses the CAD software to create a freeform mode

22、l, and the finite element software to analyse the conditions of die-cast processing. It simulates the temperature distribution of the die-body and deformation after casting under various parameters (cooling-line distance

23、 R, channel center distance L, channel diameter D), as shown in Fig. 1. It uses an abductive ne</p><p>　　Once the abductive network has constructed the relationships of the input and output die-casting varia

24、bles, an appropriate optimisation algorithm with a performance index is able to search for the optimal casting parameters. In this paper, a sound optimisation method of simulated annealing [14] is adopted. The simulated

25、annealing algorithm is a simulation of the annealing process for minimising the performance index.It has been successfully applied to die-casting die design [15], etc. The basic </p><p>　　2. Die-Casting Flow

26、 Theory</p><p>　　In the die-casting process about 80% of the time is spent in cooling cycle. The deformation of the die-casting die is caused by the non-uniform temperature distribution of the casting proces

27、sing, which affects the quality of casting part. The designer of the cooling system has to think about the total cycle and compute the deformation at every stage of the diecasting process. The die-casting process analysi

28、s includes three major stages: (1) filling stage; (2) cooling and solidification stage; (3</p><p>　　3. Create the Relationship Between Cooling System and Die-Casting Die Deformation</p><p>　　The

29、 die-casting pressure for high-pressure injection in Al alloy die-casting is approximately 30–150 Mpa; generally the injection pressure varies with time. To examine the influence of the processing pressure, Dochler and B

30、orton used a cathode ray oscilloscope and camera to analyse the pressure variation in the die-casting process, i.e. high-pressure filling, cooling and ejection.</p><p>　　Design of a die-casting die involves

31、the design of a runner, cavity balance, analysis of life span of the die (residue stress),cooling system, etc. The purpose of this study is to find the optimal cooling system of a die-casting die for casting any workpiec

32、e. The assumed casting conditions are: die-casting pressure 120 Mpa, casting speed 2.8 m/s, die-casting cycling time 20 s/cycle, pre-heat die temperature 150ºC, injection temperature 700ºC. The basic assumption

33、 for the flow in the cavity is: (</p><p>　　According to the different cooling parameters in the closed section of the part surface, there are 15 sets of data to simulate die-casting processing. The basic con

34、figuration is a free-form surface according to mould flow analysis of the 3D flow model. The surface temperature is set at the pre-heat temperature (150ºC) of the die, while the temperature of the molten metal is 70

35、0ºC. The different cooling parameters of the cooling system produce a total of 15 sets, as shown in Table 1.</p><p>　　The method for heat transfer and deformation analysis is identical, the set injectio

36、n temperatures are all 700ºC, so it is only necessary to maintain a temperature of 700ºC at the injection gate. The mould temperature is 150ºC, cooling water temperature is 40ºC, and other temperature

37、s are obtained using finite element analysis for the temperature at the instant of filling up, as shown in Figs 2 and 3.</p><p>　　Fig. 2. Temperature gradient. Fig. 3. Deformation distribution.&l

38、t;/p><p>　　The deformation analysis uses a solid model analysed by 3D flow and non-linear conditions, for finding its temperature at the boundary condition required for performing the analysis. The configured t

39、emperature of each node is input as the initial condition. Making the injection gate a boundary constraint condition serves as a 3D thermal strain condition. The mechanical properties change with the accompanying the cha

40、nge of temperature. It is obtained from an analysis of the non-linear stable stag</p><p>　　The parameters of the die-casting process are complicated and hard to control. There is no definite determination in

41、 the relation of each parameter and target function. It is different when using experimental and statistical methods for the condition of the actual die-casting. There is much restriction in the application. This study e

42、mploys a neural network to learn and train the network for the deformation of the die-casting die, and the deformation of the die in the die-casting process, and us</p><p>　　Similarly, the establishment of t

43、he relation of the input parameter (cooling system parameters: R, cooling line distance; D, channel diameter; L, channel-centre distance) and output parameter (deformation) during the die-casting process is shown in the

44、Appendix. To build a complete abductive network, the first requirement is to train the database. The information given by the input and output data must be sufficient. Thus the training factor (cooling system parameters)

45、 for the abductive network </p><p>　　Based on the development of the die-casting model, threelayer abductive networks, which are composed of cooling system parameters and the casting results (deformation), a

46、re synthesised automatically. The process is capable of predicting accurately the die-casting die deformation under various control parameters. All polynomial equations used in this network are listed in the Appendix (PS

47、E = 5.43 X 10_7).</p><p>　　Table 2 compares the error predicted by the abductive model and the simulation case. The simulation case is excluded from the 20 sets of simulation cases for establishing the model

48、. This set of data is used to test the appropriateness of the model established above. We can see from Table 2 that the error is approximately 2%, which shows that the model established above is suitable for this purpose

49、.</p><p>　　帶自由面壓鑄模具冷卻系統(tǒng)的最優(yōu)設(shè)計(jì)</p><p><b>　　摘 要</b></p><p>　　這個(gè)研究是關(guān)于有限元法和運(yùn)用到帶自由表面壓鑄模具的推斷網(wǎng)絡(luò)法。研究的目的是發(fā)現(xiàn)最佳的冷卻系統(tǒng)參數(shù)和減少壓鑄模具的變形。為了避免眾多的影響因素，壓鑄模具的自由表面采用等價(jià)的多項(xiàng)式函數(shù)非線性的結(jié)構(gòu)。根據(jù)非線性函數(shù)，包括空間開(kāi)槽

50、和孔道直徑的冷卻系統(tǒng)參數(shù)被適當(dāng)調(diào)整了。一個(gè)模仿壓鑄冷卻參數(shù)的推斷網(wǎng)絡(luò)系統(tǒng)已經(jīng)被構(gòu)造出來(lái)。這個(gè)推斷網(wǎng)絡(luò)包括許多函數(shù)節(jié)。一旦這冷卻系統(tǒng)的參數(shù)被給定，這個(gè)網(wǎng)絡(luò)系統(tǒng)便可以精確地預(yù)測(cè)壓鑄件的變形量。一個(gè)帶有性能指標(biāo)的模擬退火最佳化算法然后被應(yīng)用到神經(jīng)網(wǎng)絡(luò)，目的是探索最優(yōu)的冷卻系統(tǒng)參數(shù)和獲得一個(gè)滿意效果。</p><p>　　關(guān)鍵詞：壓鑄模具；自由形態(tài)的；神經(jīng)網(wǎng)絡(luò)；模擬退火</p><p><b

51、>　　1.引言</b></p><p>　　典型的傳統(tǒng)壓力鑄造法包括高氣壓的充填，冷卻，凝固和頂出階段。冷卻階段具有非常的重要性，因?yàn)樗茌^大地影響生產(chǎn)能力繼而影響壓鑄件的數(shù)量。眾所周知壓模鑄件大約有八成的循環(huán)時(shí)間被花費(fèi)于對(duì)熱熔進(jìn)行充分地冷卻，目的是使鑄件可以被沒(méi)有翹曲的頂出。一個(gè)成功的冷卻系統(tǒng)的設(shè)計(jì)可以顯著地減小各種因數(shù)影響，它可以減少冷卻時(shí)間、減少翹曲和相應(yīng)地增加部件的質(zhì)量。冷卻過(guò)程的主要目

52、的是維持充填和冷卻的均勻溫度。</p><p>　　相應(yīng)地,當(dāng)考慮冷卻系統(tǒng)和建立冷卻過(guò)程條件時(shí)至少有二個(gè)重要的準(zhǔn)則供設(shè)計(jì)師參考：1、達(dá)到均勻溫度；2、縮小循環(huán)時(shí)間。要實(shí)現(xiàn)這兩個(gè)目標(biāo)，設(shè)計(jì)師可能需要一個(gè)最佳的計(jì)算機(jī)輔助設(shè)計(jì)系統(tǒng)來(lái)完成一個(gè)快速和均勻的冷卻體系。在充填和冷卻過(guò)程期間，最優(yōu)系統(tǒng)設(shè)計(jì)需要進(jìn)行熱傳遞分析。這個(gè)熱分析工具將預(yù)測(cè)壓鑄件的溫度梯度和變形。</p><p>　　一般而言，傳統(tǒng)的

53、壓模設(shè)計(jì)仍然依靠經(jīng)驗(yàn)，由于缺乏鑄造流動(dòng)和熱傳遞的有利分析，設(shè)計(jì)師不能評(píng)價(jià)和控制由于壓鑄材料、膨脹和收縮引起的變形。不同冷卻系統(tǒng)參數(shù)可以引起大的溫度梯度和不同的變形。雖然有限元法軟件能夠分析一個(gè)在不同的冷卻系統(tǒng)的壓鑄模具的注射金屬壓力和熱應(yīng)力、熱膨脹和溫度分布情況的填充流動(dòng)和冷卻條件，分析模型的建立是很難的，特別是三維自由形態(tài)的幾何學(xué)。除了了解多腔模、金屬流動(dòng)和固化過(guò)程非常必要，設(shè)計(jì)師還應(yīng)該完全地掌握基本的有限元軟件。只要完全的了解壓出板

54、制造是能有效避免人員移動(dòng)麻煩的過(guò)程，引用軟件就可以達(dá)到和節(jié)省大量金錢和時(shí)間。</p><p>　　首先，對(duì)冷室壓模鑄件注射和壓鑄型腔填充排氣孔和溢流口進(jìn)行設(shè)計(jì)。當(dāng)金屬鑄件使用一個(gè)活塞進(jìn)入到一個(gè)腔內(nèi)，他會(huì)考慮金屬發(fā)生的變化和型腔內(nèi)的空氣被熔化的金屬置換。隨后Garber將會(huì)顯示太大的或太小的活塞速度可能影響鑄件的質(zhì)量Groenevelt和Kaiser研討了注射入型腔內(nèi)熔融金屬的速度的影響、流經(jīng)距離和腔內(nèi)產(chǎn)品鑄件上表

55、面的溫度。根據(jù)壓鑄件不同的澆注初始溫度實(shí)驗(yàn)可得太低的預(yù)先加熱溫度可能引起鑄塑料液堵塞流道，從而發(fā)生故障。但較高的溫度可能增加冷卻時(shí)間和減少生產(chǎn)能力。Truelove使用一個(gè)冷卻系統(tǒng)控制壓鑄過(guò)程的整個(gè)溫度，目的是獲得一最佳的傳熱特征，減少壓鑄件的熱節(jié)問(wèn)題的發(fā)生，從而改善鑄件的質(zhì)量。</p><p>　　Jong和一些人發(fā)明了一個(gè)用于熔融金屬在高氣壓壓鑄期間流動(dòng)和凝固數(shù)學(xué)方程，以便分析型腔內(nèi)壓鑄元件的溫度情況和冷卻應(yīng)

56、力。kenichiro和一些人使用有限元法分析和設(shè)計(jì)壓鑄模；結(jié)果不僅改善精度，但被考慮的因素還有許多，如壓模鑄件的壓力、澆鑄的液體的流動(dòng)速度、粘性和材料隨溫度和相變化的機(jī)械特性。使用CAD\CAE故障軟件對(duì)壓出板的系統(tǒng)設(shè)計(jì)過(guò)程的研究，目的是減少壓模設(shè)計(jì)過(guò)程中的人為誤差。它使用CAD軟件創(chuàng)造一個(gè)形式自由的模型、使用有限元軟件分析壓鑄過(guò)程的情況。它模擬壓鑄件和在不同參數(shù)（冷卻線長(zhǎng)度R、開(kāi)槽中心距L、孔道直徑D）下的鑄件變形的溫度分布，如圖1

57、所示。它使用一個(gè)推斷系統(tǒng)建立了關(guān)系圖1，冷卻通道和自由形態(tài)壓出板之間的關(guān)系，變形和冷卻系統(tǒng)參數(shù)模型之間的關(guān)系。根據(jù)推斷模擬方法，它能描繪輸入和輸出變量之間的復(fù)雜的和不確定的關(guān)系。</p><p>　　一旦推斷系統(tǒng)構(gòu)造出輸入和輸出壓力鑄造參數(shù)的關(guān)系，一個(gè)合理的帶有性能指標(biāo)的優(yōu)選法能探索出最佳的鑄造參數(shù)。在這里，一個(gè)模擬退火的測(cè)深優(yōu)化方法被采用。這個(gè)模擬退火算法是通過(guò)模擬退火過(guò)程來(lái)減少性能指標(biāo)。它已經(jīng)被成功地應(yīng)用到壓

58、鑄模具設(shè)計(jì)中等。這個(gè)基礎(chǔ)理論可以被廣泛地應(yīng)用。</p><p><b>　　2.壓鑄流動(dòng)理論</b></p><p>　　在壓鑄過(guò)程中大約80%的時(shí)間花費(fèi)在冷卻過(guò)程中。壓模鑄件的變形是由于澆鑄過(guò)程中不均勻的溫度分布引起的，它影響鑄件的質(zhì)量。冷卻系統(tǒng)的設(shè)計(jì)者不得不考慮整體循環(huán)和計(jì)算壓鑄過(guò)程中不同階段的變形。鑄造過(guò)程分析包括三主要階段：第一，澆鑄過(guò)程必須保證澆鑄充滿型腔。

59、主要的壓模鑄件流動(dòng)方程被分成五階段。在填充階段，模槽在高壓下充滿澆鑄的塑性流體。</p><p>　　3.建立冷卻系統(tǒng)和壓鑄模具變形之間的關(guān)系</p><p>　　高氣壓注射鋁合金壓鑄的鑄造壓力大約是30–150 Mpa；通常注射壓力隨時(shí)間而變。為了研究鑄造過(guò)程壓力的影響，Dochler和Borton使用陰極射線示波器和照相機(jī)分析鑄造過(guò)程中的氣壓變化，那就是說(shuō)高壓充填、冷卻和頂出。壓鑄模具

60、的設(shè)計(jì)包括流道、均勻的型腔布置、分析壓鑄模具的壽命（殘余應(yīng)力）、冷卻系統(tǒng)等等。</p><p>　　這個(gè)研究結(jié)果的目的是找到適合鑄造任何工件的壓鑄模具的最佳冷卻系統(tǒng)。假定鑄造條件是：壓鑄壓力120 Mpa、澆注速度2.8 m / s、壓鑄循環(huán)時(shí)間20s 每次、預(yù)先加熱溫度150oC、注射溫度700oC。對(duì)流入型腔的液體的基本假定：1、三維流動(dòng)；2、牛頓流體；3、層流；4、不可壓縮流體；5、流體在垂直的和水平方向無(wú)

61、流速差別。根據(jù)在零件面的閉合截面不同的冷卻參數(shù)，有15個(gè)設(shè)計(jì)數(shù)據(jù)用于模擬壓鑄過(guò)程。根據(jù)三維流動(dòng)模型的模型流動(dòng)分析，基本布局是一個(gè)自由形態(tài)的表面。壓鑄模具的表面溫度被預(yù)先加熱到一定溫度(150度)，熔融金屬的溫度被控制在700度。注射口的溫度特別需要維持在700度。模具的溫度是150度、冷卻水溫度是40度、其它的溫度在填充時(shí)需要即時(shí)使用有限元分析控制，如圖2和3所示。</p><p>　　因?yàn)楂@得其臨界溫度條件需進(jìn)

62、行分析，變形分析使用三維流動(dòng)和非線性條件對(duì)實(shí)體模型進(jìn)行分析。各節(jié)點(diǎn)的配置溫度作為初始條件被輸入。使注射口的邊界約束。條件充當(dāng)三維熱應(yīng)變條件。機(jī)械性能隨溫度變化而變。它是從非線性穩(wěn)定階段分析中獲得。上面討論的型腔流動(dòng)分析結(jié)果用應(yīng)變分析階段執(zhí)行顯示在表格1上。鑄造過(guò)程中的參數(shù)是很復(fù)雜的和難以控制的。在各參數(shù)和指標(biāo)函數(shù)之間的關(guān)系很難明確決定。用于實(shí)際壓鑄條件的實(shí)驗(yàn)方法和統(tǒng)計(jì)法是不同的。在實(shí)際運(yùn)用中有很多地限制。研究使用一個(gè)神經(jīng)網(wǎng)絡(luò)去學(xué)習(xí)和培養(yǎng)

63、一個(gè)系統(tǒng)，它用于壓鑄件的變形和鑄造過(guò)程中的變形，使用這個(gè)神經(jīng)網(wǎng)絡(luò)完成各參數(shù)的進(jìn)一步地分析。</p><p>　　圖2、溫度梯度 圖3 變形分布</p><p>　　同樣地，輸入?yún)?shù)關(guān)系的建立（冷卻系統(tǒng)參數(shù)： R,冷卻線距離: D,孔道直徑: L,開(kāi)槽中心距）和在鑄造過(guò)程期間輸出參數(shù)（變形）被顯示在附錄上。建設(shè)一個(gè)完整的推斷系統(tǒng)

64、，第一個(gè)必要條件是建立數(shù)據(jù)庫(kù)。由輸入和輸出產(chǎn)生的信息必須足夠的多。因而推斷網(wǎng)絡(luò)訓(xùn)練的導(dǎo)流因素（冷卻系統(tǒng)參數(shù)）應(yīng)該完美和制造沒(méi)有缺點(diǎn)的產(chǎn)品。表格1闡明了從三維模型流動(dòng)分析獲得的壓鑄件的冷卻系統(tǒng)參數(shù)和極限變形。</p><p>　　根據(jù)壓鑄模型的發(fā)展，三層推斷系統(tǒng)能自動(dòng)地綜合處理，它由冷卻系統(tǒng)參數(shù)和鑄件結(jié)果（變形）組成。不同的控制參數(shù)被用于這個(gè)系統(tǒng)，它能夠預(yù)先模擬壓鑄模型在不同的控制參數(shù)下面的變形。全部的多項(xiàng)式方程被