本文選題：精密模鍛 + 多目標(biāo)優(yōu)化��； 參考：《江蘇大學(xué)》2017年碩士論文

【摘要】：精密模鍛是一種少無切削的塑性加工工藝。鑒于模鍛件優(yōu)異的機(jī)械性能和較高的材料利用率,在汽車、航空航天等領(lǐng)域均獲得了廣泛應(yīng)用。本課題以一種異形汽車傳動件作為研究對象,其結(jié)構(gòu)復(fù)雜、尺寸精度要求高,模鍛成形過程中容易出現(xiàn)充不足、模具磨損嚴(yán)重及表面質(zhì)量差等問題。在實(shí)際模鍛工藝設(shè)計中,預(yù)成形幾何形狀參數(shù)對終鍛零件的質(zhì)量有較大程度的影響。因此本文采用將數(shù)值模擬、多目標(biāo)優(yōu)化、多屬性決策等理論相結(jié)合的方法對異形傳動件的預(yù)成形形狀參數(shù)進(jìn)行了優(yōu)化并針對優(yōu)化結(jié)果進(jìn)行了生產(chǎn)驗(yàn)證。首先,針對異形傳動件的模鍛成形工藝,設(shè)計了二道次成形方案與三道次成形方案。利用有限元軟件Forge模擬了兩種不同方案的成形過程并分析了其優(yōu)劣之處。根據(jù)分析結(jié)果,認(rèn)為三道次方案充型完整、模具應(yīng)力及模具磨損亦更小。在確定三道次方案后,為研究預(yù)成形形狀對終鍛件質(zhì)量的影響,選擇了預(yù)成形的三個關(guān)鍵幾何尺寸作為因素,以填充性能、模具磨損為目標(biāo)設(shè)計了L_(16)(4~3)的正交試驗(yàn)并進(jìn)行了數(shù)值模擬。其次,以數(shù)值模擬獲得的數(shù)據(jù)作為樣本集,采用支持向量機(jī)進(jìn)行學(xué)習(xí)、泛化,進(jìn)而建立了預(yù)測模型。在與BP神經(jīng)網(wǎng)絡(luò)的學(xué)習(xí)結(jié)果對比后,可以發(fā)現(xiàn)支持向量機(jī)在小樣本、存在噪聲的條件下依然具有較高的預(yù)測精度,預(yù)測模型相關(guān)系數(shù)均在85%以上。隨后根據(jù)預(yù)測模型建立顯式方程作為多目標(biāo)進(jìn)化算法的目標(biāo)函數(shù),進(jìn)而通過Matlab編制尋優(yōu)程序,獲得了Pareto最優(yōu)解集。在非劣解集內(nèi)尋找滿足決策偏好的工程應(yīng)用解的過程屬于多屬性決策范疇,本文選擇采用優(yōu)劣解距離法(TOPSIS)進(jìn)行決策,最終獲得符合工程實(shí)際需求的最優(yōu)應(yīng)用解。經(jīng)有限元與實(shí)際生產(chǎn)驗(yàn)證發(fā)現(xiàn),與優(yōu)化前的方案相比,模具磨損量降低約52.8%,充型亦較為飽滿。最后,為進(jìn)一步提高產(chǎn)品關(guān)鍵部位的尺寸精度及其表面質(zhì)量,設(shè)計了一種背壓式冷精整工藝并從理論上對其整形過程中的應(yīng)力-應(yīng)變狀態(tài)進(jìn)行了分析。分析結(jié)果認(rèn)為,施加背壓力能夠使變形金屬進(jìn)入三向壓應(yīng)力狀態(tài)并抑制金屬的反向流動,從而避免了內(nèi)腔邊緣的坍塌、折疊等缺陷的產(chǎn)生。本課題將異形傳動件的精密模鍛工藝、有限元分析理論、多目標(biāo)演化尋優(yōu)方法相結(jié)合,達(dá)到了改進(jìn)成形工藝、提高模具服役壽命、縮短設(shè)計周期的目的。研究成果為異形傳動件的量產(chǎn)提供了可靠的理論指導(dǎo),并為將來此類相似鍛件的模鍛工藝開發(fā)提供了理論與實(shí)踐依據(jù)。
[Abstract]:Precision die forging is a less cutting plastic processing technology. Because of its excellent mechanical properties and high material utilization, die forging parts have been widely used in automotive, aerospace and other fields. In this paper, a kind of special-shaped automobile transmission is studied. Its structure is complex, the dimension precision is high, the filling is easy to appear in the process of die forging, the die wear is serious and the surface quality is poor. In the actual die forging process design, the geometric shape parameters of preform have great influence on the quality of the finished forging parts. In this paper, numerical simulation, multi-objective optimization and multi-attribute decision are used to optimize the shape parameters of special-shaped transmission and the results are verified. Firstly, two pass forming scheme and three pass forming scheme are designed for the die forging process of special-shaped transmission parts. Finite element software Forge is used to simulate the forming process of two different schemes and its advantages and disadvantages are analyzed. According to the analysis results, it is considered that the three pass scheme is complete, and the stress and wear of die are smaller. In order to study the effect of pre-formed shape on the quality of final forging, three key geometric dimensions of pre-forming were selected as the factors to determine the three-pass scheme. The orthogonal test and numerical simulation for die wear were carried out. Secondly, using the data obtained by numerical simulation as sample set, support vector machine (SVM) is used to study and generalize, and then a prediction model is established. Compared with the learning results of BP neural network, it can be found that support vector machine still has high prediction accuracy under the condition of small sample and noise, and the correlation coefficient of prediction model is above 85%. Then the explicit equation is established as the objective function of the multi-objective evolutionary algorithm according to the prediction model, and the optimal solution set of Pareto is obtained by programming the optimization program by Matlab. The process of finding the engineering application solution which satisfies the decision preference in the non-inferior solution set belongs to the category of multi-attribute decision making. In this paper, we choose to choose the method of superior and inferior solution distance to make the decision, and finally obtain the optimal application solution which accords with the actual engineering demand. It is found that compared with the optimized scheme, the wear capacity of the die is reduced by 52.8%, and the mold filling is relatively full by the finite element method and the actual production verification. Finally, in order to further improve the dimensional accuracy and surface quality of the key parts of the product, a backpressure cold finishing process is designed and the stress-strain state in the shaping process is analyzed theoretically. The results show that applying back pressure can make the deformed metal enter into the state of triaxial compressive stress and restrain the reverse flow of the metal, thus avoiding the collapse of the inner cavity edge, folding and other defects. In this paper, the precision die forging technology, the theory of finite element analysis and the multi-objective evolutionary optimization method are combined to improve the forming process, prolong the service life of die and shorten the design period. The research results provide reliable theoretical guidance for mass production of special-shaped transmission parts, and provide theoretical and practical basis for the development of die forging process of this kind of similar forgings in the future.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG31

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 李超;許楨英;楊夏明;張?zhí)?王勻;;薄壁鋼筒溫擠件背壓式冷精整技術(shù)[J];鍛壓技術(shù);2016年10期

2 王久林;李萍;田野;薛克敏;汪長開;;某型號行星齒輪冷閉塞精鍛成形工藝分析[J];中國機(jī)械工程;2016年05期

3 何燕;;基于計算機(jī)有限元分析的激光沖擊強(qiáng)化鈦合金疲勞性能研究[J];熱加工工藝;2016年04期

4 夏巨諶;金俊松;鄧?yán)?王新云;;中空分流鍛造成形機(jī)理及成形力的計算[J];塑性工程學(xué)報;2016年01期

5 姜惠蘭;安星;王亞微;秦景忠;錢廣超;;基于改進(jìn)NSGA2算法的考慮風(fēng)機(jī)接入電能質(zhì)量的多目標(biāo)電網(wǎng)規(guī)劃[J];中國電機(jī)工程學(xué)報;2015年21期

6 黃遠(yuǎn)勝;楊卯生;李京社;孟文佳;;齒輪軸承鋼坯模鍛過程晶粒尺寸演變模擬[J];鋼鐵;2015年09期

7 趙志翔;;十字軸零件模鍛工藝的數(shù)字化設(shè)計[J];精密成形工程;2015年04期

8 權(quán)大赫;丁紅勝;金光秀;;彈塑性變形階段力磁效應(yīng)的有限元模擬[J];測試技術(shù)學(xué)報;2015年03期

9 姚紅兵;于文龍;楊昭;李強(qiáng);高原;李亞茹;倪文強(qiáng);;飛秒激光沖擊AZ31B鎂合金過程的數(shù)值模擬[J];光子學(xué)報;2015年04期

10 歐陽金棟;陳明和;王寧;張欽差;王輝;;C5210磷青銅薄板成形行為的尺度效應(yīng)（英文）[J];Transactions of Nonferrous Metals Society of China;2015年04期

相關(guān)碩士學(xué)位論文 前1條

1 劉勇達(dá);電流輔助TA2純鈦微塑性變形行為研究[D];哈爾濱工業(yè)大學(xué);2015年

，

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