【摘要】：鍛造是目前常用的金屬塑性成形手段之一,通過鍛造,能有效優(yōu)化微觀組織結(jié)構(gòu),改善金屬力學(xué)性能。但由于鍛造過程中涉及到高溫及金屬大變形問題,分析過程比較復(fù)雜。特別是對于模鍛技術(shù)來講,依靠已有經(jīng)驗進(jìn)行試模、修模是目前最常用的技術(shù)手段,效率低、廢品率高。隨著機(jī)械工業(yè)的不斷發(fā)展,傳統(tǒng)的模鍛工藝更難以滿足不斷提高的產(chǎn)量及品質(zhì)要求。為了解決此問題,國內(nèi)外專家學(xué)者提出對模鍛過程進(jìn)行模擬仿真的想法,試圖發(fā)現(xiàn)并解決部分在試模過程中不可預(yù)見的問題。隨著不斷發(fā)展的模鍛仿真技術(shù),傳統(tǒng)的有限元法由于網(wǎng)格的束縛及算法的限制,在面對一些比較復(fù)雜的塑性成形問題時,難以得出準(zhǔn)確結(jié)果。對此,專家學(xué)者提出了用不局限于網(wǎng)格的無網(wǎng)格法進(jìn)行金屬塑性成形的仿真分析。本文在對國內(nèi)外專家學(xué)者研究成果進(jìn)行總結(jié)梳理后,對無網(wǎng)格理論進(jìn)行了進(jìn)一步研究,并將EFGM應(yīng)用到解決某集團(tuán)鍛造廠軸承定位套鍛件鍛造過程中局部填充不足的問題中,以期找到導(dǎo)致其產(chǎn)生缺陷的原因,并對模具磨損情況進(jìn)行分析與優(yōu)化,為提高產(chǎn)品質(zhì)量、改善鍛造工藝等奠定了理論基礎(chǔ)。主要研究內(nèi)容如下:首先,對無網(wǎng)格法及其在金屬塑性成形領(lǐng)域的研究現(xiàn)狀及應(yīng)用前景進(jìn)行了分析,結(jié)合生產(chǎn)實際確定研究對象;其次,通過移動最小二乘近似原理及位移邊界條件處理兩個方面對無網(wǎng)格伽遼金法進(jìn)行了研究。用懸臂梁彎曲和拉伸的數(shù)值算例進(jìn)行了簡單的計算和驗證,確定了 EFGM為本文主要研究方法的合理性。再次,對金屬剛塑性成形基本理論進(jìn)行研究,說明了速度場近似及剛度方程基本原理,總結(jié)了算法流程,并建立了三維剛塑性EFGM模型。通過法蘭盤熱鍛過程的實驗與仿真,驗證了三維剛塑性EFGM分析模型的正確性。最后,通過對軸承定位套毛坯熱鍛成形過程的實驗與仿真,找出導(dǎo)致其出現(xiàn)局部填充不足缺陷的真正原因,提出改進(jìn)方案,并對其熱鍛成形過程中的模具磨損情況進(jìn)行分析與優(yōu)化。
[Abstract]:Forging is one of the commonly used metal forming methods. Forging can effectively optimize the microstructure and improve the mechanical properties of metals. However, due to the high temperature and large metal deformation in forging process, the analysis process is complicated. Especially for die forging technology, die repair is the most commonly used technical means, with low efficiency and high scrap rate. With the continuous development of mechanical industry, the traditional die forging process is more difficult to meet the increasing production and quality requirements. In order to solve this problem, experts and scholars at home and abroad put forward the idea of simulating the die forging process, trying to find and solve some unforeseen problems in the process of die test. With the continuous development of die forging simulation technology, the traditional finite element method is difficult to obtain accurate results in the face of some complicated plastic forming problems because of the restraint of mesh and the limitation of algorithm. In this paper, a meshless method, which is not limited to meshes, is proposed to simulate and analyze metal plastic forming. After summing up the research results of experts and scholars at home and abroad, this paper further studies the meshless theory, and applies EFGM to solve the problem of insufficient partial filling in the forging process of bearing positioning sleeve forgings in a certain group forging factory. It is expected to find out the causes of the defects and to analyze and optimize the wear of the die, which lays a theoretical foundation for improving the quality of products and the forging process. The main research contents are as follows: firstly, the research status and application prospect of meshless method in metal plastic forming field are analyzed, and the research object is determined according to the production practice. The meshless Galerkin method is studied by moving least square approximation principle and displacement boundary condition processing. The numerical examples of cantilever beam bending and stretching are used for simple calculation and verification, and the rationality of EFGM as the main research method in this paper is determined. Thirdly, the basic theory of metal rigid-plastic forming is studied, the basic principle of velocity field approximation and stiffness equation is explained, the algorithm flow is summarized, and the three-dimensional rigid-plastic EFGM model is established. The correctness of 3D rigid-plastic EFGM analysis model is verified by experiment and simulation of hot forging process of flange. Finally, through the experiment and simulation of the hot forging process of the bearing positioning sleeve blank, the real cause of the defect of partial filling is found out, and the improvement scheme is put forward. The die wear in hot forging process is analyzed and optimized.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG316

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