管子－管板液压胀接管内缺陷的产生机理及防止

摘要

全深度液压胀接技术是核电机组蒸汽发生器及其他换热器管子－管板接头普遍采用的制造工艺。液压胀接具有操作简单、胀后变形均匀、壁厚减薄率低、残余应力小等优点，但也会产生管内划伤、胀接长度超差等管内缺陷，薄壁管厚管板胀接时胀接过渡区的管子内部缺陷产生的几率更高。对液压胀接时管子长度缩短量、壁厚减薄率进行了理论计算和测量，对过渡区胀接芯轴和管子受力进行分析，表明过渡区管子内部缺陷是由于管子长度缩短效应及管子受力共同作用产生的，胀接区的划痕缺陷主要是由于芯轴损伤及金属颗粒残留引起的，未胀区胀接长度超差主要是由于芯轴设定失误引起的。通过改进胀接芯轴密封形式和限位止环的设计，证明采用芯轴保护套及非膨胀式的限位止环等工艺措施能够有效避免管内缺陷的发生。%The full depth hydraulic expansion is performed for typical nuclear power plant steam genera-tor and other heat exchanger.Simplicity of operation,evenly forming,lower thickness reduction and less residual stress are advantage of hydraulic expansion.And internal tube defect such as scratch or expan-sion depth out of tolerance may be occur,especially for thin wall tube to thick depth tubesheet expan-sion.Tube shorten calculation,wall thickness reduction examination,test and expansion mandrel force a-nalysis are performed for hydraulic expansion.Transition area internal tube defect is come out by tube shorten and force affect.Expanded area defect is come out by damage of mandrel and residual metal chip.Non -expanded area defect is come out by mandrel setting mistake.These defects can be disap-peared by mandrel sleeve,non -expanded limiting stopper for hydraulic expansion mandrel design im-provement.