密封环变形法加工中热装式夹具的设计与试验分析

发布时间：2019-01-28 09:06

【摘要】：核主泵在核电站的运行过程中起着至关重要的作用,一直被认为是核反应堆的心脏。机械密封是决定核主泵正常工作的关键技术,但机械密封组件在运行过程中极易损坏,发生泄漏,一旦泄漏量超过规定的值,很可能会造成严重的生命财产安全事故。然而目前我国对核主泵密封结构密封机理和作用机制的研究还不够深入,不能够形成整体的产品研发体系,严重制约了核电事业的发展。只有开展对核主泵密封机理的深入研究和对密封结构的创新设计研究,才能加快核电设备国产化步伐。预变形平面研磨加工方法(简称变形法)是不依赖于高精度加工设备的一种复杂曲面加工方法,有望实现核主泵用密封环的低成本高效加工。热装式夹具是实现密封环预变形的方法之一,可以实现密封环的端面变形。本文分别针对核主泵用流体静压圆锥面密封环和动压周向波度密封环,设计了两种密封环加工的热装式夹具。利用有限元分析方法,对过盈配合夹具热装过程和密封环预变形过程进行了分析,最后,进行夹具的研制和预变形平面研磨实验,验证了热装式夹具预变形加工方法的可行性。在圆锥面密封环和夹具的模型分析中,发现加载齿的过盈量与预变形倾角成明显的线性关系,因而可通过调整过盈量,对密封端面进行优化；分析了加载齿厚度与预变形倾角的关系,发现齿厚为3～5mm时,齿厚与倾角呈负相关关系,齿厚为1～3mm,齿厚对倾角的影响较小。这是因为,齿厚较小时,加载齿对密封环的作用力很小,因而与倾角大小之间不存在明显的关系。在周向波度密封环热装式夹具的设计和分析中,研究了夹具主要结构参数和加工精度对预变形精度的影响,并基于雷诺方程,对密封环的密封性能进行了分析。通过研究发现,波度区的波幅和周向长度可以通过加载齿的周向长度和过盈量来调节。基于可靠性分析,发现为保证波幅误差均方差在0.15μm以内,夹具和密封环的综合误差均方差要小于0.5μm。基于对预测加工波形的密封性能分析,发现采用变形法加工获得的波度表面和相同波幅的理想表面的密封性能有一定差异。最后,对热装式夹具进行优化设计,研制出圆锥面密封环预变形加工夹具,最后所得预变形端面变形幅值约为11.1μm,与有限元模拟结果吻合。对预变形后的密封环进行研磨,完成了锥面密封环的加工,验证了热装式夹具预变形平面研磨方法加工圆锥面密封环的可行性。
[Abstract]:Nuclear pump plays an important role in the operation of nuclear power plant and has been regarded as the heart of nuclear reactor. Mechanical seal is the key technology to determine the normal operation of the nuclear main pump, but the mechanical seal components are easy to be damaged and leak in the process of operation. Once the leakage exceeds the prescribed value, it may cause serious life and property safety accidents. However, the research on sealing mechanism and action mechanism of nuclear main pump seal structure in our country is not deep enough at present, it can't form the whole product research and development system, which seriously restricts the development of nuclear power industry. Only by studying the sealing mechanism of nuclear main pump and the innovative design of sealing structure can we speed up the localization of nuclear power equipment. Pre-deformed plane grinding method (abbreviated as deformation method) is a complex curved surface machining method which does not depend on high precision machining equipment. It is expected to realize the low cost and high efficiency machining of sealing ring for nuclear main pump. Hot-mounted fixture is one of the methods to realize the pre-deformation of seal ring, which can realize the end surface deformation of seal ring. In this paper, for hydrostatic conical seal ring and hydrostatic circumferential wave sealing ring for nuclear main pump, two hot clamps are designed for machining sealing ring. In this paper, the hot loading process of interference fit fixture and the predeformation process of seal ring are analyzed by using finite element analysis method. Finally, the feasibility of hot fitting fixture pre-deformation machining method is verified by the development of fixture and the experiment of pre-deformation plane grinding. In the model analysis of the sealing ring and fixture on the conical surface, it is found that the interference of the loaded teeth is linearly related to the predeformation inclination, so the seal end face can be optimized by adjusting the interference. The relationship between the thickness of the loaded teeth and the inclination angle of predeformation is analyzed. It is found that when the tooth thickness is 3~5mm, the tooth thickness is negatively related to the inclination angle, and the tooth thickness is 1 ~ 3 mm, and the influence of tooth thickness on the dip angle is small. This is because when the tooth thickness is small, the force of loading tooth on the seal ring is very small, so there is no obvious relationship between the loading tooth and the angle of inclination. In the design and analysis of hot mounting fixture for circumferential wave sealing ring, the influence of main structure parameters and machining precision of fixture on predeformation accuracy is studied. Based on Reynolds equation, the sealing performance of seal ring is analyzed. It is found that the amplitude and circumferential length of the wavenumber region can be adjusted by the circumferential length and interference of the loaded teeth. Based on reliability analysis, it is found that in order to ensure that the mean square deviation of amplitude error is less than 0.15 渭 m, the mean square deviation of comprehensive error of fixture and seal ring is less than 0.5 渭 m. Based on the analysis of the sealing performance of the predicted waveforms, it is found that the sealing performance of the wavenumber surface machined by deformation method is different from that of the ideal surface with the same amplitude. Finally, the predeformation jig of conical sealing ring is developed by optimizing the design of hot clamping fixture. Finally, the deformation amplitude of pre-deformed end face is about 11.1 渭 m, which is in good agreement with the finite element simulation results. The predeformed seal ring was ground, the conical seal ring was processed, and the feasibility of machining conical seal ring was verified.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM623;TG75

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