共查询到19条相似文献,搜索用时 780 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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隔板是汽轮机主要部件之一,其直径1米左右,主要由外环、叶栅、隔板体三部分组焊而成。坡口为半“U”型,深而狭窄,正反面各两条。由于隔板是汽轮机高温高压区域段的通流部分,不但焊缝质量要求高,而且变形要求严,否则会影响汽轮机的寿命和效率。一、工艺的改进采用传统的焊接方法(手工电弧焊),劳动条件差,焊接变形大,经常超出图纸要求,因此我们对工艺作了一些改进: 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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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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《焊接》2016,(9)
为了从理论上计算获得空心静叶焊接后的变形规律,以通用非线性有限元模拟软件MSC.Marc作为有限元分析软件,以某大型核电汽轮机空心静叶片为研究对象,模拟了空心静叶片进、出汽边焊缝焊接成型过程的温度场与纵向应力场分布。焊接后,焊缝位置呈现最大纵向拉应力,垂直于焊缝的两侧区域,随着离焊缝的距离的增加,拉应力逐渐减小,当距离进一步增加,出现纵向压应力并逐渐增大,当压应力出现峰值后,压应力逐渐减小并最终趋近于零。同时,计算得到了叶片焊接后的焊接变形趋势。结果表明,在叶片长度方向上,进汽边与出汽边之间的型面向内弧板卷曲,呈"V"形状,而位于出汽边焊缝以外的背弧板则正好相反,长度方向呈现"Λ"形状变形;在宽度方向上,出汽边位置的背弧板变形量最大,整体变形方向为向内弧面卷曲变形。将模拟得到的焊接变形趋势、变形方向与关节臂式三坐标检测结果进行了对比,两者相吻合。 相似文献
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材质为2Cr13的汽轮机动叶片在调质处理后发现动叶片榫头表面网状裂纹。通过金相检测、宏观断口观察、化学成分分析、力学性能测试以及扫描电镜分析等一系列的理化试验,分析了动叶片榫头表面裂纹的性质及形成原因。试验结果表明:该汽轮机动叶片榫头表面网状裂纹是由于该部位短时过热过烧所造成的锻造裂纹。本研究对研究汽轮机动叶片在生产制造过程中出现的裂纹等质量问题具有积极意义。 相似文献
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某汽轮机下半缸铸造后产生尺寸偏差,隔板定位面螺栓孔轴向错位,造成上下缸无法直接组装运行,急需进行补焊返修.为了评估补焊工艺的可行性,采用数值计算的方法,对汽轮机下半缸多道多层补焊过程进行了三维数值模拟,预测了缸壁补焊后关键部位的变形量.结果表明,采用18道焊缝分区跳焊的工艺,补焊后中分面平整度在2 mm内;汽封轴向尺寸偏差小于1 mm;汽封开档尺寸从喉口到出口先膨胀后收缩,最大变形量为0.886 mm;变形量的预测为制定和评估正确的补焊工艺提供理论依据和技术支持. 相似文献
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S. K. Albert C. R. Das V. Ramasubbu A. K. Bhaduri S. K. Ray Baldev Raj 《Journal of Materials Engineering and Performance》2002,11(3):243-249
A root-cracked blade in a high-pressure steam turbine of a nuclear power plant had to be replaced with a new blade by cutting
the shroud to remove the cracked blade. This necessitated in situ welding of a new shroud piece with the existing shroud after
the blade replacement. The in situ welding of the shroud, a 12% Cr martensitic stainless steel with tempered martensite microstructure,
was carried out using gastungsten arc welding and 316L austenitic stainless steel filler metal followed by localized postweld
heat treatment at 873 K for 1 h using a specially designed electrical resistance-heating furnace. Mock-up trials were carried
out to ensure that sound welds could be made under the constraints present during the in situ repair welding operation. In
situ metallography of the repair weld after postweld heat treatment confirmed the adequate tempering of the martensitic structure
in the heat-affected zone. Metallurgical investigations carried out in the laboratory on a shroud test-piece that had been
welded using the same procedure as employed in the field confirmed the success of the in situ repair operation. The alternate
option available was replacing the cracked blade and the shroud piece to which it is riveted with a new one, reducing the
height of all the blades attached to the shroud by machining, riveting the blades with reduced height to the new shroud, and,
finally, dynamic balancing of the entire turbine after completion of the repair. This option is both time-consuming and expensive.
Hence, the successful completion of this repair welding resulted in enormous savings both in terms of reducing the downtime
of the plant and the cost of the repair. The turbine has been put back into service and has been operating satisfactorily
since December 2000. 相似文献
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V. N. Detsik 《Metal Science and Heat Treatment》1996,38(2):75-77
Steel 20kh 13 is widely used in the production of blades of steam turbines and machine parts that require a high erosion resistance in operation with maintenance of a high impact strength. After hardening with the use of HFC heating or bulk hardening of blades, the latter exhibit warping or insufficiently high erosion resistance. Even hardening with the use of currents of superhigh frequencies does not eliminate completely the deformation of parts. Local heating by an electron beam decreases deformation considerably even under conditions of a fused surface layer in the steel and increases its erosion resistance markedly. For this reason, it is of interest to investigate the effect of electron-beam treatment on the mechanical and operational properties of turbine blades.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 25 – 27, February, 1996. 相似文献
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汽轮机末级叶片表面防水蚀处理工艺及发展 总被引:2,自引:1,他引:1
针对国内桌汽轮机厂生产的135MW机组汽轮机频频在投运后第1次检修时,即发现低压转子末级叶片进汽边侧存在多条裂纹的情况,介绍了汽轮机末级叶片的防水蚀表面处理工艺的种类及发展,总结了末级叶片的表面防护措施可分为局部加覆盖层和表面淬硬两大类.对各种处理工艺的特点、可靠性、防护层的性能要求、质量检查及测试方法进行了探讨,并根据今后大容量机组的特点,提出了叶片表面防护工艺的发展方向. 相似文献