钛合金波纹管快速热成形技术
发布时间：2018-08-16 15:42
【摘要】：金属波纹管是工业领域重要的结构件,它可以通过自身的伸缩来补偿管道或管形件因热变形和机械变形带来的位移变化,同时还有减振去噪等功能。钛合金以其密度小、强度高、抗腐蚀能力强、高温稳定性好等优势,逐渐被用于制造高性能的金属波纹管。但是钛合金难变形的特征,使其制造成为了难题。超塑成形虽可实现钛合金波纹管的成形,但是成本高、生产效率低的弊端严重限制了该工艺的工业应用。本文中采用电流辅助热成形工艺实现了钛合金波纹管的快速热成形,并对电流辅助热成形工艺进行了深入研究,拓展了其实际应用。首先,进行了TC4钛合金的电流辅助弯曲成形试验,探究钛合金在电流作用下的弯曲变形规律。基于云母板和聚四氟乙烯塑料两种绝缘材料设计的成形模具,可实现板材在通电加热条件下的弯曲成形。试验结果表明:电流强度(温度)愈低,弯曲圆角半径愈小,弯曲件出现裂纹的倾向愈大;当无裂纹出现时,弯曲件在低电流强度(温度)下出现了回弹现象,且电流强度越低,回弹量越大,在高电流强度(温度)下由于板材温度分布不均匀出现了弯曲件向内侧收缩的现象。然后,基于MSC.MARC软件进行了钛合金波纹管成形的数值模拟,分析了不同工艺参数对成形结果的影响。模拟结果表明:补料高度愈大,波纹管的壁厚减薄量愈小;合模速度过快很容易导致坯料出现失稳起皱的缺陷,且缺陷通常出现在最下端的波纹处。同时,利用数值模拟初步确定了波纹管成形的试验参数。最后,针对Ti31和TC4两种钛合金进行了波纹管的电流辅助成形试验。基于陶瓷模具的成形装置,可实现坯料在通电加热条件下的气压胀形。试验结果表明:运用自动TIG焊制造的筒坯质量明显优于人工氩弧焊制造的筒坯;电流辅助热成形工艺制造钛合金波纹管的效率很高,整个成形过程可控制在6min内;经酸洗处理后的波纹管表面质量良好,无明显的凹坑、划伤等表面缺陷;合理的轴向补料使得钛合金波纹管的壁厚分布变得更加均匀,其中Ti31合金波纹管的最大减薄率为18%,TC4合金波纹管的最大减薄率为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.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG146.23
本文编号：2186429
[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.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG146.23
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