共查询到19条相似文献,搜索用时 93 毫秒
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蒸汽轮机自带冠静叶隔板是蒸汽轮机通流部分的静子部件,其制造精度直接影响到整个机组的效率。在实际生产中发现自带冠静叶隔板焊后节圆直径变形大,严重影响了隔板通流尺寸精度。文中针对蒸汽轮机自带冠静叶隔板生产过程中产生的焊接变形问题,采用定点测试方法,进行现场跟踪监测,获得了有效的焊接变形数据。并对自带冠静叶隔板主焊缝焊接后和热处理后的节圆半径变形、直径变形和节圆收缩率进行了深入分析,为了减小焊接菜,在隔板的结构设计方面应控制主焊缝进汽侧与出汽侧的坡口深度比值在1.0-1.15范围内。 相似文献
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蒸汽轮机自带冠静叶隔板是蒸汽轮机通流部分的静子部件 ,其制造精度直接影响到整个机组的效率。在实际生产中发现自带冠叶隔板焊后节圆直径变形大 ,严重影响了隔板通流尺寸精度。文中针对蒸汽轮机自带冠叶隔板生产过程中产生的焊接变形问题 ,采用定点测试方法 ,进行现场跟踪监测 ,获得了有效的焊接变形数据。并对自带冠叶隔板主焊缝焊接后和热处理后的节圆半径变形、直径变形和节圆收缩率进行了深入分析。为了减小焊接变形 ,在隔板的结构设计方面应控制主焊缝进汽侧与出汽侧的坡口深度比值在 1.0~ 1.15范围内 相似文献
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三维静叶隔板采用三元流理论设计,应用于汽轮机能提高效率3%~5%,对节能、高效型汽轮机的发展具有非常重要的意义。由于三元流理论对气流运动方式要求非常严格,因而对隔板喉宽和总出汽边面积等重要性能参数要求也非常严格,一般选择焊接方式生产。最近,我厂承接了国内首台125MW热电联供汽轮机,其三维静叶隔板原计划亦采用焊接方式生产。因生产工期短,任务量非常大,我厂原有焊接工艺和设备按期完成生产任务困难较大。根据我厂生产实践经验,铸造隔板与焊接隔板相比具有节约原材料30%~35%、机加工费用降低20%及生产周期缩短25%~30%等优点,具有非常可观的经济效益。 相似文献
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宜昌大桥钢箱梁隔板焊接变形的控制技术 总被引:1,自引:0,他引:1
介绍了宜昌长江公路大桥的结构形式和特点,分析了钢箱梁中横隔板单元件在焊接过程中的变形趋势,采取相应工艺措施,使焊接变形得到了有效的控制。 相似文献
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在我国电力行业,铸铁隔板运行数年后,铸铁板体与不锈钢导叶连接处,由于气流冲击(简称气蚀)致使叶根与板体脱离,严重影响了机组的运行:很多单位都曾尝试过用焊接方法来解决,但效果一直不好。由于铸铁与不锈钢之间的焊接难度比较大,铸铁板体侧在焊接过程中,焊道附近时常出现微裂纹或与板体母材熔合不好的现象, 相似文献
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阐述了200MW汽轮机焊接隔板变形这一在国内电站中多次出现的问题,以及由于隔板变形而对机组带来的危害.强调了在隔板发生严重变形时对隔板进行焊接加固的必要性,概述了隔板检查方法,包括隔板表面缺陷、内部缺陷、通流间隙、挠曲变形等的检查,以及隔板加固的工艺要点. 相似文献
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球冠结构在焊接过程中产生的焊接变形是关系到结构安全性能的重要指标.为了保证球冠焊接构件的可靠性,准确推断球冠结构焊接变形,有必要针对球冠结构的焊接变形进行数值试验分析.基于大型有限元软件ABAQUS开发相应的焊接程序,对焊接过程中温度场、结构变形进行了数值模拟,并将模拟结果与相关理论值及试验值进行对比分析.结果表明,数值试验结果与理论结果基本吻合,满足工程要求.在此基础上,对球冠结构的焊接过程进行三维有限元分析,得到了球冠结构焊接变形随球冠壁厚、焊接坡口形式及焊接顺序的变化规律,为控制结构的焊接变形提供了依据. 相似文献
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基于有限元软件SYSWELD建立了大型薄板装甲钢结构的焊接有限元模型,采用Local-Global方法研究了焊接顺序对薄板结构焊接变形的影响. 通过对比焊缝截面宏观形貌,利用SYSWELD热源拟合工具,建立了适合现场焊接工艺的双椭球热源模型. 采用热弹塑性有限元法分析了T形和对接接头的焊接过程,获得了局部塑性应变和焊缝刚度,进而模拟了不同焊接顺序下薄板结构变形情况. 结果表明,现场焊接顺序下结构中部薄板焊接变形严重,最大变形量为9.6 mm,模拟结果与试验结果吻合较好;采用优化的焊接顺序,可有效控制薄板焊接变形,最大变形量可减小75%. 相似文献
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基于薄壁壳体的焊接变形,研究了壳体变形理论、T形接头的激光焊工艺,利用激光焊技术解决了其焊接变形大的问题。根据激光热源、壳体材料的特点制定焊接工艺流程,通过改变激光入射角的方式,解决薄壁壳体上T形接头的激光焊问题。通过试验验证,确定激光焊参数,在保证焊接质量的前提下,做到焊接变形小、焊缝成形美观,壳体焊接变形控制在0. 12 mm以下。 相似文献
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《Science & Technology of Welding & Joining》2013,18(4):264-268
AbstractThe effectiveness of welding with a trailing heat sink in reducing the angular distortion of a weld has been experimentally investigated with focus on the cooling position. A numerical model of welding with a trailing heat sink is constructed through the comparison of measured values of weld penetration, thermal cycles and angular distortion with those calculated. On the basis of this model, the effect of welding heat input conditions on the reduction in angular distortion is discussed to evaluate the versatility of welding with a trailing heat sink. The results indicate that the choice of an appropriate cooling position behind the welding heat source is essential for the effective reduction in angular distortion. The reduction in angular distortion by the heat sink at the appropriate cooling position increases with the heat input parameter Qnet/h, where Qnet is the weld heat input and h is the thickness of the plate. 相似文献
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焊接变形是影响焊接结构质量和生产率的主要问题之一,焊接变形的存在不仅影响着焊接结构的制造过程,而且影响着焊接结构的使用性能。一般认为,焊接过程中材料的不均匀受热、板厚方向的热梯度、材料的局部非协调塑性应变以及焊接残余应力的作用是产生各种焊接变形的根本原因。焊接变形预测方法大都基于有限元分析。文中详述了国内外有关焊接变形预测技术的最新研究进展,具体介绍了热弹塑性有限单元法、固有应变法以及基于传统有限元的优化设计法与人工神经网络模型等先进的焊接变形预测方法。 相似文献
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A single-layer pulsed gas metal arc weld of structural steel S355J2+N with a thickness of 5 mm is experimentally and numerically investigated. Two tack welds are considered in the numerical simulation into two different ways. First, the tack welds are represented by elements belonging to the initial material. This implies that the “tack weld material” was not exposed to any thermal load or phase transformation before actual welding was performed. The weld seam is shortened and there is an influence on the stiffness of the whole structure affecting the calculation result. Secondly, the tack welds were simulated as conducted in the experimental welding procedure. The cases considering tack welding are compared to a simulation neglecting tack welding and to the experimental results.The influence of tack welds on the calculated welding-induced distortion is clarified and a contribution to an improved simulation-based prediction of welding-induced distortion is possible by modeling tack welding according to the realistic fabrication procedure. 相似文献
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《中国有色金属学会会刊》2020,30(1):76-89
The distribution of temperature and then the distribution of residual stress and distortion in the stiffened aluminum alloy Al6061-T6 plates under the metal inert gas (MIG) welding process were investigated by three dimensional thermo-mechanical coupled finite element model using Ansys software. The properties of materials were considered temperature-dependent and the filler metal was added to the workpiece by the element birth and death technique. In three modes of current, two different speeds and two various sequences, the distribution of residual stress and distortion were calculated and analyzed. The results showed that increase in welding speed decreased the vertical deflection in the plate, transverse shrinkage and angular distortion of plate and the lateral deflection of stiffener, but increased the maximum longitudinal tensile stress in the plate and stiffener. Furthermore, increase in current increased the residual stress and deformation in the plate and stiffener, and the change in the welding sequence changed the distribution of the distortion in the plate and the stiffener without significant change in the distribution of the longitudinal residual stress. 相似文献