机械密封端面信息采集及应用

【作者】 胡小云；

【导师】 宋鹏云；

【作者基本信息】 昆明理工大学 ， 机械设计及理论， 2004， 硕士

【摘要】 机械密封是由至少一对垂直于旋转轴线的端面在液体压力和补偿机构弹力(或磁力)的作用以及辅助密封的配合下保持贴合并相对滑动而构成的防止流体泄漏的装置。机械密封使用于许多场合密封各种流体，是当今泵和压缩机中流体密封的支柱。经过几代人的努力，机械密封接触面间存在液膜这一事实早己为实验所证实，但对机械密封的润滑机理尚未完全搞清，不能完全以设计参数来准确预测密封的运转性能。因此，对端面间摩擦工况及机理、端面的温度分布、密封组件的动力学特性等进行研究，将对改进机械密封的设计意义重大。针对机械密封的理论和试验研究现状，本文就机械密封的端面信息分类、机械密封端面信息的理论分析和试验测试以及机械密封端面信息的应用等方面开展了研究工作。在分析了目前国内外机械密封研究现状的基础上，本文第一次利用信息论的理论，对机械密封的各种参数进行了分类，提出了机械密封静态信息和动态信息的概念，并就各种信息的采集测试方法分别作了比较说明。机械密封端面温度分布是影响机械密封性能的重要因素。本文在综合比较国内外端面温度计算方法的基础上，提出了一种较为合理的端面温度计算方法，该方法改变了过去对热传导角以及散热系数的经验设定，采用公式确定的方法，能针对不同密封摩擦副尺寸和操作工况计算相应的系数，具有更强的说服力。通过在相同边界条件下对各种温度计算方法的结果进行比较，该方法在节省时间效率的情况下，与试验测试结果更为接近，从而为机械密封端面信息的理论计算提供了依据和比较。温度的理论分析计算中由于边界条件的确定很难符合实际，试验测试依然是机械密封端面温度研究的主要方法。本文在分析比较了各种温度测试方法后，选择了用热电偶来测量端面的温度。把市场购得的罗钉热电偶经过改装，导入到背部钻有盲孔的静环中，便做成了本文端面温度的测量装置。经试验证明，该方法制备的热电偶输出线性好，与理论输出最大误差不超过9％。端面扭矩是端面摩擦状态的直接反映，也是机械密封端面的重要动态信息之一。本文放弃了目前国内外普遍采用的端面扭矩测量方法，对传统的机械密封结构进行了改装，设计了一个既可安装静环，又可便于扭矩测量的带薄壁圆筒的压盖。本文中所用的在薄壁圆筒外圆周对称贴上应变计来测量端面扭矩的方法，是一种新的端面扭矩测量方法。通过试验证明，该方法制备的扭矩传感器输出线性好，能方便直观地观测端面扭矩的动态变化。本文针对不同工况下对端面温度信息和端面扭矩信息进行了采集测量。对理论数据与实验数据进行比较发现，两种温度结果的偏差只是理论温升的6． 3％，扭矩测量结果与理论结果的偏差也仅是理论扭矩的5． 8％，说明了端面温度和端面扭矩测量方法的准确性和可行性。本昆明理工大学硕士学位论文文还对机械密封在无水和有水两种情况下的温升做了对比实验，实验结果表明，无水(干摩擦)状态下的温升增长率是有水状态下的6-7倍，而且温度呈现无限升高趋势;相比较而言，在有水状态下，端面温升在4分钟左右就趋于稳定。这为进一步利用温升增长率来判断端面的摩擦状态提供了一定的理论参考。 本文对机械密封的端面信息进行了综合考虑，研究了机械密封的静态信息与动态信息的潜在关系，利用润滑数L考虑表面信息的特点，得到了涉及润滑数L的温升与端面扭矩之间的关系式。拓 最后，本文针对机械密封的端面信息(如表面粗糙度、端面温度以及端面扭矩等)在热变形计算、摩擦状态判断等方面的应用作了探索，为以后的机械密封理论与试验研究提供了参考。 本论文的主要工作和获得的主要成果为: (l)利用信息论的知识，首次系统地对机械密封的各种参数进行了分类，并就各种端面信息的测试方法以及研究现状作了简要的介绍。 (2)综合国内外的端面温度计算方法，提出了一种较为合理的温度计算方法。该方法在需要确定温度的情况下能快速计算出结果，摆脱了数值算法的繁琐性，同时又不失一定的准确性。 (3)在众多的温度测量方法中选择了用热电偶测取端面的温度。通过在不同工况下的实验发现，用热电偶测温方便、直接，特别适合机械密封这种点状温度测量。 (4)对传统的机械密封结构进行改装，提出了一种新的端面扭矩测量方法。该方法只是借助常用的电阻应变片，避免了传统测量方法的繁琐和不准确性，对研究机械密封的端面摩擦状态是一次新的尝试。 (5)应用涉及端面粗糙度信息的润滑数对具有流体静压润滑和微凸体接触的混合摩擦状态下的摩擦系数进行了理论推导，并得到了温升与润滑数之间的关系式，为利用温升来判断端面的摩擦状态做了一定的探索性研究。更多还原

【Abstract】 Mechanical face seals are the equipments containing at least a pair of end faces perpendicular to axis of rotation, which are working in the liquid pressure and the elasticity of compensation organizations(or magnetic force) as well as the coordination of auxiliary seals to keep integrating closely and sliding relatively, take affect to prevent liquid leaking. Mechanical face seals are used to seal various fluids on a lot of occasions , it is the pillar of fluid seals in pump and compressor at present. Via the effort of several generation, though it was confirmed by experiments long ago that there is liquid film between mechanical sealing contact surface, the lubrication mechanism of mechanical face seals isn’t still mastered. The design parameter can’t be used to forecast the operation performance of mechanical face seals accurately. Therefore, the research focusing on the friction operating mode and mechanism the temperature distribution the dynamics property of sealing assembly will be significant in improving the design of mechanical face seals.According to the present research situations of mechanical face seals in theory and test, the work such as the information classifications of end faces, the theoretical calculations of the face information of mechanical seal face and experimental measurement as well as the application of the face information of mechanical seal face is done in this paper.On the basis of analysis about domestic and international research situation in mechanical sealing at present, various parameters for the mechanical face seals are classified using the knowledge of information theory for the first time. The concepts of the static and dynamic information of mechanical sealing are put forward, and the measurement methods of various information are also compared respectively.The temperature distribution of seal face is an important factor that can affect the performance of mechanical sealing. In this paper a kind of relatively reasonable temperature calculation method was put forward on the comprehensive foundation of the domestic and international temperature calculation methods. The convection coefficient and heat flow path direction are specified by means of formula calculation rather then artificial setting in this temperature calculation method, in which the parameters can be calculated according to the difference of structure size and operation condition. Compared with results of other temperature calculation method in identical boundary condition, the result of this method is more close to the result of test under the condition of saving time. Therefore, the method offers the basis and comparison for the theoretical calculation of the face information of mechanical seal.Experimental measurement is still the major method of the temperature research of sealing face because the determination of the boundary conditions is difficult to accord with the reality in the temperature theoretic calculation. Thermocouple was selected to measure the temperature of end face on the basis of comparison of various temperature test methods in this paper. After a thermocouple purchased from market was refitted and fixed to the stator who has two holes on the back, the temperature sensor was got. It is proved by experiment that the output linearity of the thermocouple is good and the biggest error compared with theoretical output does not exceed 9%.The torque of end face is the direct reflection of the friction state of end face and also the one of important dynamic information of mechanical seal face. A new kind of torque measurement method rather than the present torque measurement technique was applied to measure the torque of mechanical sealing face after having refitted the traditional structure in this paper. A lid containing a thin wall cylinder was designed to install stator and measure torque. The method who pastes strain gauge symmetrically outside thin wall cylinder to measure the torque of end face in this paper is a kind of new torque measurement technique. It was proved by test t更多还原