發(fā)布時間：2018-03-18 01:02

  本文選題：鑄態(tài)7075鋁合金　切入點：強力熱反旋　出處：《南昌航空大學》2017年碩士論文　論文類型：學位論文

【摘要】：鑄態(tài)7075鋁合金所具有的低密度、高比強、耐高壓、耐腐蝕等優(yōu)點,已成為近年來研究較多的難成形材料之一。筒形件強力熱反旋成形,不僅可以有效地減小零件的設計壁厚、減輕重量、提高疲勞性能,而且可消除鑄造缺陷、細化晶粒提高塑性,已成為鑄態(tài)7075鋁合金筒形件成形的最有效的方法之一。然而,鑄態(tài)7075鋁合金筒形件在強力旋壓過程中經(jīng)常出現(xiàn)的擴徑,是旋壓中的重要缺陷之一,嚴重影響旋壓件成形質(zhì)量和成形精度的提高。因此,本文基于ABAQUS有限元仿真平臺建立并優(yōu)化了相關有限元模型,研究了工藝參數(shù)對筒形件擴徑度的影響規(guī)律,并獲得了筒形件各道次強力熱反旋過程的最優(yōu)工藝參數(shù)和基于擴徑的成形極限。本文主要研究內(nèi)容與研究結(jié)果如下:(1)基于ABAQUS/Explicit平臺,解決了有限元建模過程中的關鍵技術(如旋輪參數(shù)的選擇,高溫條件下鑄態(tài)7075鋁合金材料本構(gòu)的建立,接觸條件、加載條件和網(wǎng)格劃分的建立),建立了符合實際且穩(wěn)定的鑄態(tài)7075鋁合金多道次強力熱反旋有限元模型,并通過實驗驗證了所建立模型的可靠性。(2)基于所建立的有限元模型,研究了工藝參數(shù)(旋輪進給速度、各道次減薄量、芯模溫度、芯模轉(zhuǎn)速、芯模與筒形件間摩擦和旋輪與筒形件間摩擦)對筒形件擴徑度的影響規(guī)律,結(jié)果表明:隨著旋輪進給速度的增大,前三道次的擴徑度隨之增大,第四道次的擴徑度先減小后增大;隨著各道次減薄量的增加,擴徑度都基本表現(xiàn)出增長的趨勢;各道次的擴徑度隨著芯模溫度的升高都呈現(xiàn)先減小后增大的趨勢;隨著芯模轉(zhuǎn)速的增加,第一道次和第四道次的擴徑度隨之先減小后逐漸增大,第二道次和第三道次的擴徑度變化并不明顯;隨著芯模與筒形件間摩擦系數(shù)的增大,第一道次和第二道次的擴徑度呈現(xiàn)先減小后逐漸增大的趨勢,而第三道次和第四道次的擴徑度出現(xiàn)增大的趨勢;旋輪與筒形件間摩擦的增大對各道次擴徑度影響較小�；谏鲜鲅芯�,得到各工藝因素的最佳取值范圍。(3)采用有限元模擬、正交試驗與響應面法建立了工藝參數(shù)與擴徑耦合關系模型,從而得出各個道次基于擴徑的最優(yōu)工藝參數(shù)值為:第一道次旋壓成形過程的最優(yōu)工藝參數(shù)為減薄量為2.522mm,芯模溫度為276.3℃,旋輪進給速度為0.521mm/s;第二道次旋壓成形過程的最優(yōu)工藝參數(shù)為減薄量為1.757mm,芯模溫度為214.8℃,旋輪進給速度為0.726mm/s;第三道次旋壓成形過程的最優(yōu)工藝參數(shù)芯模與筒形件間摩擦系數(shù)為0.079,芯模溫度為138.7℃,減薄量為1.478 mm;第四道次旋壓成形過程的最優(yōu)工藝參數(shù)為芯模轉(zhuǎn)速為3.864r/s,芯模溫度為108.3℃,芯模與筒形件間摩擦系數(shù)為0.061。(4)基于上述耦合關系模型,建立了各道次基于擴徑的成形極限預測模型,并研究了擴徑度影響顯著因素對擴徑成形極限的影響規(guī)律:第一道次的成形極限隨著旋輪進給速度的增大,呈現(xiàn)先增大后減小的趨勢;第二道次的成形極限隨著旋輪進給速度的增大先減小后增大,隨芯模溫度的增大而增大;第三道次的成形極限隨著芯模溫度的增大而減小,隨芯模與筒形件間摩擦系數(shù)的增大而增大;第四道次的成形極限隨著芯模溫度的增大而增大,隨芯模與筒形件間摩擦系數(shù)的增大而增大�；谏鲜鲅芯�,建立了筒形件強力熱反旋過程基于擴徑的成形極限圖。
[Abstract]:Low density cast 7075 Aluminum Alloy with the high specific strength, high pressure resistance, corrosion resistance and other advantages, has become more difficult to form the research in recent years. One of the material cylinder hot power backward spinning process, the design of wall not only can effectively reduce the thickness of parts, reduce weight, improve the fatigue performance, but also can eliminate the casting defects, grain refinement and plasticity, has become one of the 7075 Aluminum Alloy cast cylinder forming the most effective method. However, the as cast 7075 Aluminum Alloy cylindrical parts often appear in the spinning process of expanding, is one of the most important defects in spinning, spinning forming quality and serious influence improving the forming accuracy. Therefore, this paper ABAQUS finite element simulation platform was established and optimized based on finite element model, studied the influence of process parameters on the expanding of a cylinder, and the optimal tube pass strong thermal reverse rotation process The process parameters and the forming limit based on expanding. The main research contents and results are as follows: (1) based on the ABAQUS/Explicit platform, to solve the key technology of the finite element modeling process (such as roller parameters, under the condition of high temperature cast 7075 Aluminum Alloy material constitutive model established, contact conditions, loading conditions and the grid, the establishment) practical and stable cast 7075 Aluminum Alloy multipass hot power spinning finite element model is established, and tested the reliability of the model. (2) based on the established finite element model, the effects of process parameters (feed speed, each time thickness, core temperature, rotational speed of mandrel, the mandrel and the cylinder friction between the roller and the cylinder friction) influences, expanding a degree of cylinder showed that with the increase of feed speed, the first three times the diameter increasing, Fourth times the diameter of the first decreases and then increases with the increase of each pass; thinning ratio, expanding degree basically showed a growth trend; each pass is expanding with the increase of core temperature will increase firstly and then decrease with the increase of rotational speed of mould; the first line and fourth times the diameter decreases and then increases gradually along with the degree of change in diameter, second times and third times the expansion is not obvious; with the increase of friction coefficient between the mandrel and the cylinder, the first and the second times of the diameter of first decreases gradually increasing trend. The third pass and fourth passes of the expanding degree appeared increasing trend; the roller and the cylinder friction between the increase of the expansion of small size effect. Based on the above research, the optimal range of various process factors. (3) by using the finite element simulation, orthogonal test and response surface method the establishment of the industry The parameters and expanding coupling model, so that each pass the optimal process parameters of expanding based on Value: first pass spinning forming process parameters for optimal thinning quantity is 2.522mm, core temperature is 276.3 DEG C, the roller feed speed is 0.521mm/s; the optimum process parameters of second pass spinning forming process for the reduction of 1.757mm, mold temperature is 214.8 DEG C, the roller feed rate is 0.726mm/s; third pass spinning forming process of friction coefficient of the optimal process parameters of the mandrel and tube is 0.079, mold temperature 138.7 C, reduction of 1.478 mm; fourth pass spinning the optimal process parameters for the mandrel speed is 3.864r/s, core temperature is 108.3 DEG C, the mandrel and the cylinder friction coefficient between 0.061. (4) model based on the coupling relationship, establishes each pass based on expanding the forming limit prediction model, and study the expansion Influence of significant factors influence on the diameter of the expanding limit: the first forming limit with the increase of feed speed, first increased and then decreased; second times with the increase of the forming limit of roller feed rate decreases first and then increases, increases with increasing core temperature; the forming limit of third times decreased with increasing core temperature, coefficient increased with the increase of the mandrel and the cylinder friction; forming limit fourth times increases with the increase of core temperature, with the mandrel and the cylinder friction coefficient increase increases. Based on the above research a tube, hot power backward spinning process of forming limit diagram based on expanding.

【學位授予單位】：南昌航空大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG306

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