【摘要】：輕量化彎曲型材成形技術(shù)是先進塑性加工技術(shù)發(fā)展的趨勢,薄壁鎂合金彎曲件應(yīng)用于航空航天、交通運輸?shù)刃袠I(yè)具有減重、降低能耗等優(yōu)勢。AZ31鎂合金的室溫成形性能較差,采用傳統(tǒng)彎曲成形方法不能保證彎曲件成形質(zhì)量及尺寸精度。本文采用溫?zé)釓埩@彎成形,通過改善溫度加載模式、加熱型材、添加預(yù)拉伸的方法使型材在熱-力作用下提高其彎曲性能�；貜椇凸に噮�(shù)優(yōu)化是AZ31鎂合金型材溫?zé)釓埩@彎成形亟待解決的問題。本文采用理論分析、有限元模擬及實驗研究相結(jié)合的方法,對AZ31鎂合金型材的溫?zé)釓埩@彎成形工藝進行研究,分析了溫度、預(yù)拉伸量等工藝及材料因素對型材繞彎成形性的影響規(guī)律。本文研究內(nèi)容和結(jié)論如下:采用Gleeble-3800熱模擬實驗機對AZ31擠壓態(tài)鎂合金型材進行拉伸實驗,獲得AZ31鎂合金流動應(yīng)力應(yīng)變關(guān)系;采用MSC.Marc軟件,建立鎂合金溫?zé)嶙冃文Ｐ?建立三維彈塑性熱-力耦合有限元模型,通過模擬溫度加載模式、不同繞彎成形溫度及不同預(yù)拉伸量,分析繞彎過程的應(yīng)力應(yīng)變場、溫度場,獲得優(yōu)化的U形擠壓態(tài)AZ31鎂合金型材的繞彎成形工藝參數(shù)及工藝條件;并進行AZ31鎂合金型材的溫?zé)釓埩@彎成形實驗。模擬及實驗結(jié)果表明,工藝參數(shù)對回彈的影響規(guī)律一致。采用局部加熱型材的方式,將型材加熱至170℃,在型材端部添加0.2%的預(yù)拉伸量,保持端部張力的添加將型材繞彎110°后卸載,可以得到回彈量較小、表面起皺少的U形AZ31鎂合金繞彎成形件。繞彎過程中彎曲溫度的升高,可以減小型材的回彈,但溫度升高到170℃以上,繞彎成形性較好,其彎曲變形量較大,易發(fā)生減薄;隨著預(yù)拉伸量的增大,其回彈量一開始降低,繼續(xù)增大預(yù)拉伸量,對回彈量不發(fā)生顯著變化;隨著彎曲角度的增大,型材彎曲成形性能變差,到110°以上,型材內(nèi)壁易發(fā)生畸變。
[Abstract]:Lightweight bending profile forming technology is the development trend of advanced plastic processing technology. Thin wall magnesium alloy bending parts are used in aerospace, transportation and other industries, such as weight reduction, energy consumption reduction, etc. AZ31 magnesium alloy has poor room temperature formability. The traditional bending method can not guarantee the forming quality and dimensional accuracy of bending parts. In this paper, the bending behavior of the profile is improved by improving the temperature loading mode, heating the profile and adding pretension. Springback and optimization of process parameters are the urgent problems of AZ31 magnesium alloy profile forming. In this paper, theoretical analysis, finite element simulation and experimental study are used to study the forming process of AZ31 magnesium alloy profile by thermal tension winding, and the temperature is analyzed. The influence of pretension and material factors on the bending formability of profile. The main contents and conclusions of this paper are as follows: the flow stress-strain relationship of AZ31 magnesium alloy was obtained by using Gleeble-3800 thermal simulation machine to carry out tensile test on AZ31 extruded magnesium alloy profile; Using MSC.Marc software, the thermal deformation model of magnesium alloy is established, and the three-dimensional elastic-plastic thermo-mechanical coupling finite element model is established. By simulating the temperature loading mode, different bending temperature and different pretension amount are simulated. The stress and strain field and temperature field of the bending process are analyzed, and the optimized forming process parameters and process conditions of U-shaped extruded AZ31 magnesium alloy profile are obtained. The forming experiment of AZ31 magnesium alloy profile by thermal tension winding was carried out. The simulation and experimental results show that the effect of process parameters on springback is consistent. By heating the profile to 170 鈩，

本文編號：2337868