Ω型双螺杆泵主轴疲劳分析与优化设计

发布时间：2018-10-26 14:12

【摘要】：双螺杆泵具有流量稳定、压力平稳、自吸能力强、效率高及稳定性强等优点,广泛应用于石油化工、航运、污水处理等行业。但由于输送介质、工作环境等复杂多变,螺杆泵易发生疲劳破坏,因此,对双螺杆泵主轴疲劳强度的分析研究具有重要意义。本文以某采油储运系统使用的Ω型双螺杆泵设计为应用背景,分析了双螺杆泵在额定工况下运行时转子系统的工作特性,建立了主轴载荷模型;通过试验测试,获得主轴材料疲劳寿命曲线,据此进行了主轴的疲劳分析;并以提高可靠性为目标对双螺杆泵主轴结构进行了优化设计。本文建立了典型螺杆转子端面型线方程和转子系统三维模型,进行了转子动平衡优化设计;运用FLUENT分析了双螺杆泵在额定工况下流道内的压力分布规律,为双螺杆泵主轴载荷预测提供数据支持。考虑自身重力、齿轮传动、介质压力、缝隙回流等因素,建立了双螺杆泵主轴轴向力和径向力的载荷模型,为双螺杆泵主轴疲劳分析和优化设计奠定基础。论文进行了螺杆泵主轴常用材料05Cr17Ni4Cu4Nb不锈钢的疲劳拉伸试验,分析获得了该材料的疲劳特性曲线;在此基础上,考虑应力集中和平均应力修正等因素,利用ANSYS Workbench软件分析了以该不锈钢作为主轴材料的双螺杆泵在某采油储运系统中使用的疲劳寿命满足要求。但基于疲劳可靠性设计理论分析表明,主轴疲劳可靠度仅为0.8643。为解决主轴疲劳可靠度较低的问题,基于响应面法和有限元分析,本文以主轴直径、倒角度数和动力端轴伸长度为优化变量,各变量的极限值和主轴法向最大变形为约束条件,主轴危险截面承受的等效交变应力最小为优化目标,建立了双螺杆泵主轴优化设计模型。优化结果显示,与原设计相比,优化后的主轴危险截面承受的等效交变应力降低了 26.2%,法向最大变形量降低了 25.2%,无限寿命可靠度和疲劳安全系数均满足设计要求。
[Abstract]:Double screw pump has the advantages of stable flow, steady pressure, strong self-priming ability, high efficiency and strong stability. It is widely used in petrochemical, shipping, sewage treatment and other industries. However, due to the complexity of conveying medium and working environment, the fatigue failure of the screw pump is easy to occur, so it is of great significance to analyze and study the fatigue strength of the spindle of the double screw pump. In this paper, based on the design of 惟 type double screw pump used in an oil recovery storage and transportation system, the working characteristics of the rotor system under rated operating conditions are analyzed, and the spindle load model is established. The fatigue life curve of spindle material is obtained by test, and the fatigue analysis of spindle is carried out according to this curve, and the structure of double screw pump spindle is optimized with the aim of improving reliability. In this paper, the profile equation of the end face of the typical screw rotor and the three dimensional model of the rotor system are established, and the optimal design of the rotor dynamic balance is carried out. The pressure distribution law of double screw pump under rated working condition is analyzed by FLUENT, which provides data support for load prediction of double screw pump spindle. The load models of axial and radial forces of double screw pump spindle are established considering the factors such as self gravity gear transmission medium pressure and slot reflux etc. It lays a foundation for fatigue analysis and optimization design of double screw pump spindle. The fatigue tensile test of 05Cr17Ni4Cu4Nb stainless steel, a common material of screw pump spindle, was carried out in this paper, and the fatigue characteristic curve of the material was obtained. On this basis, considering the factors such as stress concentration and average stress correction, the fatigue life of the double screw pump with stainless steel as the main shaft material is analyzed by using ANSYS Workbench software to meet the requirements in an oil recovery storage and transportation system. However, the fatigue reliability of spindle is only 0.8643 based on the theoretical analysis of fatigue reliability design. In order to solve the problem of low fatigue reliability of spindle, based on response surface method and finite element analysis, this paper takes spindle diameter, chamfer degree and shaft extension length of power end as optimization variables, and the limit value of each variable and the maximum deformation of spindle normal direction are the constraint conditions. The optimal design model of double screw pump spindle is established. The optimization results show that, compared with the original design, the equivalent alternating stress of the dangerous section of the optimized spindle is reduced by 26.2kum, and the maximum normal deformation is reduced by 25.2. The reliability of infinite life and the factor of fatigue safety meet the design requirements.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH327

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