液路截止球阀低温密封性能分析与改进设计

发布时间：2018-01-22 18:54

本文关键词： 球阀热分析有限元法故障树　出处：《国防科学技术大学》2012年硕士论文　论文类型：学位论文

【摘要】：液路截止球阀是以球体作为关闭件的阀门，具有流体阻力小，开关迅速，密封性好，寿命长，，可靠性高等优点，得到广泛运用。工业界在以液路截止球阀为代表的球阀密封研究方面取得了一定进展，但低温条件下的密封可靠性问题仍是一个难题。由于环境和介质不同，构成球阀密封副的材料具有多样性，试验和测试过程中很难模拟实际运用状态。本文在液路截止球阀设计使用方面，结合低温性能故障，以液路截止球阀漏液故障为顶事件，分析该球阀设计使用过程中存在的问题，对导致泄露事件的各种原因进行分析，确定密封材料冷流特性和密封比压设计不合理等底事件是导致泄露的主要原因，针对具体原因进行机理分析和试验验证。通过理论分析和对比，确定改进目标和设计方案。进行有限元法仿真分析，针对球阀压力、温度和力矩进行仿真模拟，进行热分析和应力应变分析，分析可能引起的疲劳和破坏。针对该球阀的三维模型进行简化和网格划分，建立了便于进行有限元数值计算的模型，在网格划分时对阀芯、导套、密封帽等重要部件进行加密处理。分别设定不同温度和力矩条件，模拟开启和关闭状态进行仿真计算。在边界参数确定后，对应力和变形数据进行详细分析，得到不同工况条件下最大应力和变形状态，分析得到液路截止球阀可靠工作的力矩要求和温度范围。在仿真分析的基础上，对液路截止球阀进行改进设计，增加密封冗余设计和碟簧补偿机构。针对阀体、阀芯、碟簧、密封帽、密封圈等零部件进行分析，确定设计参数。运用经验公式对球阀连接件的强度、操纵力、剪切力、拉出力、抗冲击能力、可靠性试验次数等进行详细计算。针对温度变化引起的变形问题，运用线性尺寸变化公式进行各部分间隙和体积变化量计算，得到体积变形量的变化趋势。通过选择合理参数和材料，计算出密封比压、密封参数、预紧力矩等球阀设计关键指标。开展试验研究，结合理论计算和液路截止球阀实际工况，对球阀进行高温密封检测试验、低温储存试验、振动试验、地面温度循环试验、可靠性试验、高低温循环试验、交变湿热试验、不同介质热循环试验以及X光检测项目测试，验证设计参数和计算数据。结合系统给定的条件，考虑合适的边界条件，确定的不同试验项目进行整机性能测试。所有试验均满足设计要求，与理论分析和仿真结果吻合。特别是针对泄露情况和碟簧工作状态进行全面测试和检验，试验结果与理论分析相互验证。
[Abstract]:Liquid cut off ball valve is a valve with ball as closing piece. It has the advantages of low fluid resistance, quick switch, good sealing, long life, high reliability and so on. Some progress has been made in the field of sealing of ball valves represented by liquid cut off ball valves, but the problem of sealing reliability at low temperature is still a difficult problem. Because of the difference of environment and medium, the materials that make up the sealing pair of ball valve are diverse, so it is difficult to simulate the actual application state in the process of test and test. Combined with the low temperature performance fault, this paper analyzes the problems existing in the design and use of the ball valve, and analyzes the various causes leading to the leakage event, taking the leakage fault of the liquid cut off ball valve as the top event. The main cause of leakage is to determine the cold flow characteristics of sealing materials and the unreasonable design of seal specific pressure. The mechanism analysis and experimental verification are carried out for the specific reasons, and the theoretical analysis and comparison are carried out. Identify improvement goals and design options. The finite element method is used to simulate the pressure, temperature and torque of the ball valve, and thermal analysis and stress-strain analysis are carried out. To simplify and mesh the three-dimensional model of the ball valve, the finite element numerical calculation model is established, and the valve core and guide sleeve are divided into two parts. Sealing cap and other important components are encrypted. Different temperature and torque conditions are set to simulate the state of opening and closing. After the boundary parameters are determined the corresponding force and deformation data are analyzed in detail. The maximum stress and deformation state under different working conditions were obtained, and the torque requirements and temperature range for the reliable operation of the liquid-cut ball valve were analyzed. On the basis of simulation and analysis, the design of liquid cut off ball valve is improved, the redundant seal design and disc spring compensation mechanism are added, and the parts such as valve body, valve core, disc spring, seal cap, seal ring and so on are analyzed. The design parameters are determined. The strength, control force, shear force, pull force, impact resistance and reliability test times of ball valve connectors are calculated in detail by empirical formula. The change trend of volume deformation is obtained by using linear size change formula to calculate the gap and volume change of each part. Through selecting reasonable parameters and materials, the sealing specific pressure and sealing parameters are calculated. Key parameters of ball valve design such as pre-tightening moment. To carry out experimental research, combined with theoretical calculation and actual working conditions of the liquid-cut ball valve, the test of high-temperature sealing, low-temperature storage test, vibration test, ground temperature circulation test and reliability test are carried out. High and low temperature cycle test, alternating humid heat test, different medium thermal cycle test and X ray test item test to verify the design parameters and calculation data. Considering the given conditions of the system, consider the appropriate boundary conditions. All the tests meet the design requirements, which are consistent with the theoretical analysis and simulation results. In particular, the leakage situation and disc spring working state are comprehensively tested and tested. The experimental results are verified by theoretical analysis.
【学位授予单位】：国防科学技术大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH134

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