【摘要】：金屬波紋管是工業(yè)領域重要的結構件,它可以通過自身的伸縮來補償管道或管形件因熱變形和機械變形帶來的位移變化,同時還有減振去噪等功能。鈦合金以其密度小、強度高、抗腐蝕能力強、高溫穩(wěn)定性好等優(yōu)勢,逐漸被用于制造高性能的金屬波紋管。但是鈦合金難變形的特征,使其制造成為了難題。超塑成形雖可實現(xiàn)鈦合金波紋管的成形,但是成本高、生產效率低的弊端嚴重限制了該工藝的工業(yè)應用。本文中采用電流輔助熱成形工藝實現(xiàn)了鈦合金波紋管的快速熱成形,并對電流輔助熱成形工藝進行了深入研究,拓展了其實際應用。首先,進行了TC4鈦合金的電流輔助彎曲成形試驗,探究鈦合金在電流作用下的彎曲變形規(guī)律�；谠颇赴搴途鬯姆蚁┧芰蟽煞N絕緣材料設計的成形模具,可實現(xiàn)板材在通電加熱條件下的彎曲成形。試驗結果表明:電流強度(溫度)愈低,彎曲圓角半徑愈小,彎曲件出現(xiàn)裂紋的傾向愈大;當無裂紋出現(xiàn)時,彎曲件在低電流強度(溫度)下出現(xiàn)了回彈現(xiàn)象,且電流強度越低,回彈量越大,在高電流強度(溫度)下由于板材溫度分布不均勻出現(xiàn)了彎曲件向內側收縮的現(xiàn)象。然后,基于MSC.MARC軟件進行了鈦合金波紋管成形的數(shù)值模擬,分析了不同工藝參數(shù)對成形結果的影響。模擬結果表明:補料高度愈大,波紋管的壁厚減薄量愈小;合模速度過快很容易導致坯料出現(xiàn)失穩(wěn)起皺的缺陷,且缺陷通常出現(xiàn)在最下端的波紋處。同時,利用數(shù)值模擬初步確定了波紋管成形的試驗參數(shù)。最后,針對Ti31和TC4兩種鈦合金進行了波紋管的電流輔助成形試驗�；谔沾赡＞叩某尚窝b置,可實現(xiàn)坯料在通電加熱條件下的氣壓脹形。試驗結果表明:運用自動TIG焊制造的筒坯質量明顯優(yōu)于人工氬弧焊制造的筒坯;電流輔助熱成形工藝制造鈦合金波紋管的效率很高,整個成形過程可控制在6min內;經酸洗處理后的波紋管表面質量良好,無明顯的凹坑、劃傷等表面缺陷;合理的軸向補料使得鈦合金波紋管的壁厚分布變得更加均勻,其中Ti31合金波紋管的最大減薄率為18%,TC4合金波紋管的最大減薄率為16%。
[Abstract]:Metal corrugated pipe is an important structural part in industrial field. It can compensate for the displacement change caused by thermal deformation and mechanical deformation of pipe or tube by its own expansion and expansion, as well as the functions of vibration and noise reduction and so on. Titanium alloy has been used to manufacture high performance metal bellows because of its advantages such as low density, high strength, strong corrosion resistance and high temperature stability. However, the characteristics of difficult deformation of titanium alloy make its manufacture a difficult problem. Although superplastic forming can realize the forming of titanium alloy bellows, the disadvantages of high cost and low production efficiency seriously limit the industrial application of this process. In this paper, the rapid hot forming of titanium alloy bellows is realized by means of current assisted hot forming process, and the process of current assisted hot forming is deeply studied, which expands its practical application. Firstly, the current assisted bending forming test of TC4 titanium alloy was carried out to investigate the bending deformation of titanium alloy under the action of current. Based on mica sheet and PTFE two kinds of insulating materials, the forming die can realize the bending forming of sheet metal under the condition of electrification and heating. The experimental results show that the lower the current intensity (temperature) is, the smaller the radius of the bend corner is, and the greater the tendency of crack is, and the springback occurs at low current strength (temperature) when there is no crack. The lower the current intensity is, the greater the rebound is. The bending part shrinks to the inside due to the uneven temperature distribution of the sheet metal at high current strength (temperature). Then, the numerical simulation of titanium alloy bellows forming is carried out based on MSC.MARC software, and the influence of different process parameters on the forming results is analyzed. The simulation results show that the higher the feeding height, the smaller the thickness of corrugated pipe is, and the higher the die speed is, the more unstable and wrinkled the billet is, and the defect usually occurs at the bottom of corrugation. At the same time, the experimental parameters of bellows forming are preliminarily determined by numerical simulation. Finally, the current-assisted forming test of corrugated tube was carried out for Ti31 and TC4 titanium alloys. The forming device based on ceramic die can realize the bulging of billet under the condition of electric heating. The results show that the quality of the tube made by automatic TIG welding is obviously better than that of the tube made by artificial argon arc welding, and the efficiency of making titanium alloy corrugated tube by current-assisted hot forming process is very high, and the whole forming process can be controlled in 6min. The surface quality of the bellows treated by acid washing is good, no obvious pits, scratching and other surface defects, reasonable axial feeding makes the wall thickness distribution of titanium alloy corrugated tubes more uniform, The maximum thinning rate of Ti31 alloy corrugated tube is 18 and the maximum thinning rate of TC4 alloy corrugated tube is 16.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TG146.23

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