复合材料护环的切削加工与过盈装配的有限元模拟

发布时间：2018-01-31 18:55

  本文关键词： 复合材料护环 车削加工 热膨胀 过盈装配　出处：《哈尔滨工业大学》2014年硕士论文　论文类型：学位论文

【摘要】：近年来，随之我国国民经济的快速发展，我国对电力的需求也随之不断增加，为此对大容量、大功率发电机组的需求就显得尤为迫切。电机中的转子护环是发电机的重要部件。在发电机正常运转时，护环受到来自转子的交变压力及两者旋转时巨大的离心力，为此对护环的力学性能和护环与转子的装配要求尤其苛刻。现役的奥氏体反磁钢电机护环自重大、依赖进口，制约着我国大容量发电机的自主发展。于此同时，纤维树脂基复合材料在工程上的应用却越来越成熟、越来越广泛，其比强度比模量高、磁导率低、加工成型方便、成本低。纤维树脂基复合材料护环作为工程结构件应用，需要对材料进行一定的机械加工，才能满足装配及精度的要求。护环与转子之间为过盈配合，两者之间的合理装配对于转子的正常运转具有重要的意义。 针对以上问题，本文设计并制造了600MW级汽轮发电机用碳纤维复合材料护环。首先，选择复合材料体系—树脂基体、增强纤维、固化剂、促进剂，确定制备工艺、进行铺层设计。其次对复合材料进行了车削加工及已加工表面的粗糙度测试，从而优化了切削参数。再者，对复合材料的热膨胀系数及热膨胀变形量进行了实验和模拟分析，最终进行了复合材料护环缩比件与转子进行装配的仿真模拟，外护环与转子的装配实验完成了铺垫工作。 本文使用有限元软件对复合材料的以下两个方面进行了模拟仿真： 1）转子与护环之间的过盈装配采用热装法与冷装法结合的方法，为了保证两者之间装配实验的顺利进行，分别模拟了护环在高温下内表面的径向膨胀量、转子在低温下的径向收缩量。模拟结果表明：对于600MWe级汽轮发电机用碳纤维复合材料护环的缩比件（缩小比例为4:1），其在120℃时的径向膨胀量为0.0447mm，转子在-110℃时的径向收缩量为0.681mm。同时还模拟了玻璃纤维及其与碳纤维混杂复合材料在高温下的热膨胀量，结果表明，玻璃纤维复合材料护环的径向热膨胀量在温度升高至120℃达到0.389mm，比碳纤维复合材料护环提高了9倍。 2）护环与转子之间的过盈配合量对于两者工作时的应力有很大影响，为此本课题模拟了转子与护环缩比件在不同过盈装配量时的应力分布情况，以及护环受到过盈装配产生的离心力的作用下，接触面上的应力分布情况。结果表明，护环及转子在0.2mm过盈量装配时，护环内边界的应力达到20.42MPa，小于碳纤维复合材料护环的纵向压缩强度900MPa。护环在50Hz频率下旋转过程中，环向最大膨胀位移量约为0.05mm，在60Hz极限频率下的环向最大膨胀位移量约为0.075mm，该膨胀量处于护环与转子间的过盈配合量的设计范围内，，因此不会影响转子与护环间的整体配合。
[Abstract]:In recent years, with the rapid development of China's national economy, the demand for electricity in our country is also increasing, so the large capacity. The demand of high-power generator set is particularly urgent. The rotor ring is an important part of generator. When the generator is running normally. The ring is subjected to the alternating pressure from the rotor and the great centrifugal force when they rotate. Therefore, the mechanical properties of the retaining ring and the assembly requirements of the ring and rotor are particularly harsh. Dependence on imports restricts the independent development of large capacity generators in China. At the same time, fiber resin matrix composites are more and more mature and widely used in engineering, their specific strength ratio modulus is high, permeability is low. Fiber resin matrix composite ring is used as an engineering structure, which needs to be machined. Only in order to meet the requirements of assembly and accuracy, the interference fit between the retaining ring and the rotor is necessary, and the reasonable assembly between the two is of great significance to the normal operation of the rotor. Aiming at the above problems, the carbon fiber composite ring for 600MW turbogenerator is designed and manufactured. Firstly, the composite system-resin matrix, reinforcing fiber, curing agent and accelerator are selected. The preparation process was determined and the layering design was carried out. Secondly, the cutting parameters were optimized by turning the composites and measuring the roughness of the machined surfaces. The thermal expansion coefficient and thermal expansion deformation of composite material were tested and simulated. Finally, the assembly of composite retaining ring and rotor was simulated. The assembly experiment of the outer protection ring and the rotor has completed the paving work. In this paper, the following two aspects of composite materials are simulated by finite element software: 1) the interference assembly between rotor and retaining ring adopts the method of hot loading and cold assembling. In order to ensure the smooth assembly experiment between the two, the radial expansion of the inner surface of the retaining ring at high temperature is simulated respectively. The radial shrinkage of the rotor at low temperature. The simulation results show that for the carbon fiber composite retaining ring of 600MWe class turbogenerator, the shrinkage ratio is 4: 1. The radial expansion is 0.0447 mm at 120 鈩

本文编号：1479759