【摘要】：鋁合金薄壁帽型材不僅強(qiáng)度高、質(zhì)量輕、抗腐蝕性強(qiáng),同時(shí)還能實(shí)現(xiàn)工業(yè)生產(chǎn)中節(jié)能、環(huán)保的特點(diǎn),已被廣泛地應(yīng)用在航空、航天、汽車等高科技領(lǐng)域中。數(shù)控繞彎法是此類零件的重要加工方法之一,但由于該成形方法涉及多模具、多因素的耦合作用,使得其在成形過程中容易發(fā)生截面畸變、回彈、失穩(wěn)起皺等缺陷,尤其是截面畸變嚴(yán)重制約著彎曲件的成形質(zhì)量以及成形精度。因此,本文采用數(shù)值模擬技術(shù)并結(jié)合實(shí)驗(yàn)及理論分析的方法對(duì)帽型材繞彎成形過程中截面畸變行為進(jìn)行深入研究,研究?jī)?nèi)容和結(jié)果如下:(1)結(jié)合鋁合金薄壁帽型材彎曲成形特點(diǎn),解決了接觸、摩擦、加載、邊界條件等關(guān)鍵技術(shù)問題,建立了鋁合金薄壁帽型材繞彎成形三維有限元模型,并驗(yàn)證了該模型的可靠性。(2)采用所建立的可靠模型,研究獲得了5052鋁合金帽型材繞彎成形過程中應(yīng)力應(yīng)變的分布特征,揭示了截面畸變的產(chǎn)生機(jī)理,提出了衡量截面畸變的指標(biāo)。結(jié)果表明:隨著繞彎進(jìn)程的進(jìn)行,型材的等效應(yīng)力和等效應(yīng)變逐漸增大;截面變形是型材受到切向拉應(yīng)力和切向壓應(yīng)力的合力所致,一旦變形超過了其允許的范圍,就發(fā)展為畸變。(3)研究獲得了彈性模量、泊松比、相對(duì)彎曲半徑、彎曲速度等成形參數(shù)對(duì)帽型材繞彎成形截面畸變的影響規(guī)律。研究表明:隨著彈性模量、硬化指數(shù)、彎曲模與型材間摩擦系數(shù)、壓塊與型材間摩擦系數(shù)、夾塊與型材間摩擦系數(shù)、相對(duì)彎曲半徑、壓塊助推速度的增大,截面畸變呈減小趨勢(shì);隨著屈服強(qiáng)度、強(qiáng)度系數(shù)、彎曲模與型材間隙、壓塊與型材間隙、夾塊與型材間隙、彎曲角度的增大,截面畸變?cè)龃?適當(dāng)增大彎曲速度,有利于減小截面畸變;而泊松比、防皺塊與型材間摩擦系數(shù)、防皺塊與型材間間隙的改變對(duì)截面畸變影響不大。
[Abstract]:Aluminum alloy thin-wall cap profile not only has high strength, light weight, strong corrosion resistance, but also can realize the characteristics of energy saving and environmental protection in industrial production. It has been widely used in aviation, aerospace, automobile and other high-tech fields. Numerical control winding and bending method is one of the most important machining methods for this kind of parts. However, due to the coupling action of multi-die and multi-factor, the forming method is prone to the defects of section distortion, springback and buckling. Especially section distortion seriously restricts the forming quality and precision of bending parts. Therefore, in this paper, numerical simulation technique and experimental and theoretical analysis are used to deeply study the section distortion behavior in the forming process of cap profile. The research contents and results are as follows: (1) combined with the characteristics of aluminum alloy thin-walled cap profile bending forming, The key technical problems such as contact, friction, loading and boundary conditions are solved. A three-dimensional finite element model of aluminum alloy thin-walled cap profile is established, and the reliability of the model is verified. (2) the reliability model is adopted. The distribution characteristics of stress and strain in the forming process of 5052 aluminum alloy cap profile are studied. The mechanism of section distortion is revealed and the index to measure section distortion is put forward. The results show that the equivalent stress and strain increase gradually with the bending process, and the cross section deformation is caused by the combined force of the tangential tensile stress and the tangential compressive stress, once the deformation exceeds its allowable range, (3) the influence of forming parameters, such as elastic modulus, Poisson's ratio, relative bending radius and bending speed, on section distortion of cap profile is studied. The results show that: with the increase of elastic modulus, hardening index, friction coefficient between bending die and profile, friction coefficient between press block and profile, friction coefficient between clip and profile, relative bending radius, pushing speed of press block, The section distortion decreases with yield strength, strength coefficient, gap between bending die and profile, gap between press and profile, gap between clip and profile, and section distortion increases with the increase of bending angle, appropriate increase of bending speed, Poisson's ratio, friction coefficient between wrinkle block and profile, and gap between wrinkle block and profile have little effect on section distortion.
【學(xué)位授予單位】：南昌航空大學(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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本文編號(hào)：2287419