發(fā)布時(shí)間：2018-02-13 17:13

  本文關(guān)鍵詞： 鋁合金 復(fù)雜截面 中空分流 終成形載荷 變形均勻性　出處：《中北大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：鋁合金異形復(fù)雜截面構(gòu)件的幾何形狀復(fù)雜，中心為圓形凸臺(tái)，凸臺(tái)周圍有較高的加強(qiáng)筋，整體成形十分困難。由于需承受較大的沖擊載荷，構(gòu)件要求有較高的力學(xué)性能。如采用形狀規(guī)則的圓柱體毛坯進(jìn)行直接成形，就會(huì)產(chǎn)生邊緣部充不滿，，筋部折疊等嚴(yán)重的質(zhì)量問題，同時(shí)有終成形載荷過大、局部變形不均勻等缺陷。對(duì)于此類復(fù)雜截面構(gòu)件的整體成形，為避免上述缺陷，需要進(jìn)行預(yù)成形設(shè)計(jì)的改進(jìn)，從而滿足構(gòu)件較高的力學(xué)性能要求。 本課題采用有限元模擬和實(shí)驗(yàn)相結(jié)合的方法，研究鋁合金異形復(fù)雜截面構(gòu)件的整體成形過程中金屬流動(dòng)規(guī)律，對(duì)成形過程中構(gòu)件應(yīng)力、應(yīng)變、流動(dòng)速度及載荷等物理場量進(jìn)行分析，研究了構(gòu)件在終成形時(shí)成形載荷較高、變形不均勻的原因，分析了高筋部分折疊、邊緣部分充不滿等缺陷的形成機(jī)理。 針對(duì)上述問題，根據(jù)分流成形原理，提出鋁合金異形復(fù)雜截面構(gòu)件預(yù)成形改進(jìn)設(shè)計(jì)方案：采用中空的預(yù)成形坯料，使金屬材料在成形過程中實(shí)現(xiàn)分流成形，降低材料充填模腔的阻力及終成形載荷，提高材料變形均勻性，避免了成形過程中折疊及充不滿缺陷。 研究了預(yù)成形坯料關(guān)鍵結(jié)構(gòu)參數(shù)：中空凹面方向、坯料凹面的半徑R與坯料半徑R0之比（R/R0）、邊緣部分與中空凹面的高度差ΔH和原方案坯料高度H之比（ΔH/H）對(duì)終成形應(yīng)力、應(yīng)變及載荷的影響規(guī)律，得出合理的預(yù)成形坯料關(guān)鍵結(jié)構(gòu)參數(shù)，使終成形載荷相比原方案降低了30%，改進(jìn)后的成形方案比原方案金屬變形更加均勻。 采用改進(jìn)后的成形方案進(jìn)行實(shí)驗(yàn)試制，成功生產(chǎn)出合格工件。在產(chǎn)品不同部位上取試樣，進(jìn)行沖擊韌性、金相組織以及力學(xué)性能的對(duì)比，證明改進(jìn)后的成形方案各項(xiàng)指標(biāo)較原方案有較大提高，驗(yàn)證了此工藝方案的合理性。
[Abstract]:The geometric shape of the aluminum alloy special-shaped and complex cross-section members is complex, the center is a circular convex table, and there are high reinforcement bars around the convex table, so it is very difficult to form the whole. If a cylindrical blank with regular shape is used for direct forming, serious quality problems such as filling of edges, folding of tendons, and excessive final forming load will occur. In order to avoid the defects mentioned above, it is necessary to improve the preforming design to meet the higher mechanical performance requirements of this kind of complex cross-section members. In this paper, the method of finite element simulation and experiment is used to study the metal flow law in the forming process of the aluminum alloy special-shaped and complex cross-section members, and the stress and strain of the members during the forming process are analyzed. Based on the analysis of physical field such as flow velocity and load, the causes of high forming load and uneven deformation are studied, and the forming mechanism of the defects such as the folding of the high reinforcement and the dissatisfaction of the edge are analyzed. In view of the above problems, according to the principle of shunt forming, an improved design scheme of aluminum alloy special-shaped complex cross-section member preforming is put forward: the hollow preformed blank is used to make metal material realize shunt forming in the forming process. The resistance and final forming load of material filling die cavity are reduced, and the uniformity of material deformation is improved, and the folding and filling defects are avoided in the forming process. The key structural parameters of preformed billet, such as the hollow concave direction, the ratio of the radius R of the blank concave to the radius R0 of the blank, the height difference between the edge part and the hollow surface, and the ratio of the height of the original blank (螖 H / H) to the final forming stress, are studied. According to the influence of strain and load, the key structural parameters of preformed billet are obtained, the final forming load is reduced by 30% compared with the original scheme, and the improved forming scheme is more uniform than that of the original scheme. The qualified workpiece was successfully produced by using the improved forming scheme. Samples were taken from different parts of the product, and the impact toughness, metallographic structure and mechanical properties were compared. It is proved that each index of the improved forming scheme is much higher than that of the original scheme, and the rationality of the process scheme is verified.
【學(xué)位授予單位】：中北大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG306

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