【作者】 吴涛；

【导师】 计三有；

【作者基本信息】 武汉理工大学 ， 机械设计及理论， 2013， 硕士

【摘要】 螺纹联接是利用螺纹零件构成的一种可拆卸联接。它具有预紧、联接、紧固、密封等功能,在各种机械和结构中被广泛采用。螺纹联接一般都具有自锁性,拧紧后一般不会自动松脱。但是,在冲击、振动、变载荷、高温或者温度变化的作用下,联接会发生失效松脱。工程中,常常因为螺纹联接的松动而发生重大事故。因此,对于螺纹联接的防松研究就成为目前国内外十分重视的课题。本课题来源于同上海振高螺母有限公司的横向合作项目“变牙型螺母的防松性能分析”。具体研究内容及研究成果如下：(1)本文总结了国内外螺纹联接防松及弹塑性有限元分析的研究现状。对本次分析运用到的弹塑性分析理论和接触分析理论进行了简要阐述,并简单介绍了ANSYS程序分析弹塑性问题和接触问题的方法与过程。(2)利用Yamamoto提出的方法计算出普通螺纹联接的轴向力在各圈螺纹的分布规律,得出结论为普通螺纹联接的受力分布是从螺母与被联接件的接触面开始往远离该接触面方向的各圈螺纹呈现逐个递减趋势。同时,分别建立了普通螺纹联接的弹性有限元分析模型和弹塑性有限元分析模型,通过有限元计算,得到了弹性分析模型和弹塑性分析模型的轴向力分布规律,并且该规律与理论结果是一致的。(3)详细分析了变牙型螺纹联接的受力,得出变牙型螺纹联接的各圈螺纹的径向力要大于轴向锁紧力,并且各螺纹的受力均匀分布的理论结论,据此分析了变牙型螺纹联接的防松原理。同时建立了变牙型螺纹联接的有限元弹塑性分析模型,通过有限元分析验证了理论结果。(4)通过对比变牙型螺纹联接和普通螺纹联接的各圈螺纹处轴向力和法向力分布规律,得到变牙型螺纹联接的各圈螺纹受力均匀,能够避免滑牙等导致联接松动的问题,并且,在同等预紧力下具有比普通螺纹联接更大的法向力,并且法向力分布均匀,因此变牙型螺纹联接就具有更大的螺纹间摩擦力,从而比普通螺纹联接更加可靠,防松性能更显著。更多还原

【Abstract】 The threaded connection is a kind of detachable connection using the threaded parts. It has many functions such as preloading, connection, fastening, sealing and so on. It is widely used in a variety of mechanical and structural areas. Threaded connection generally have a self-locking property. Generally, it will not automatically loose. However, in the role of shocking, vibration, variable loads, a high temperature or temperature changes, the connection will occur loosening failure. In engineering areas, the loosening of the threaded connection cause a major of accidents. Therefore, the locking property research of threaded connection has become a very important issue at home and abroad. This subject comes from the horizontal cooperation project "The analysis on the locking property of the thread of shape-changed tooth", which is cooperated with the Shanghai Zhengao Nuts Limited Company. Specific studies and research results are as follows:(1) This paper summarizes the research status of the locking property of threaded connection and elastoplastic finite element analysis at home and abroad. A brief description is made of the elastoplastic analysis theory and contact analysis theory. Also a brief introduction is made to the analysis methods and processes of elastoplastic problems and contact problems in ANSYS program.(2) Using the method proposed by Yamamoto, the paper calculate the distribution law of the axial force in each circle of the thread in the ordinary threaded connection. The ordinary threaded connection force distribution is a decreasing trend from the first circle of thread which is closest to the contact face between the nut and the connecting component to the circles far away from the face. Meanwhile, the elastic analysis and elastoplastic analysis finite element model of ordinary thread connection are established. Using the finite element method, the distribution law of axial force of the elastic analysis model and the elastic-plastic analysis model is obtained. and the law is consistent with the theoretical results.(3) Analysis the forces of the shape-changed tooth thread in detail. The results come to that the force distribution is uniform in all the circles of the shape-changed tooth thread, and the radial force is greater than the axial locking force. Accordingly analysis the locking mechanism of the shape-changed tooth thread. At the same time, establish the elastoplastic finite element analysis model of the shape-changed tooth thread. The obtained results by finite element analysis are consistent with the theoretical results.(4) By comparing the axial force distribution law and the normal force distribution law of these two kinds of threaded connections. The result is that the force distribution of the shape-changed tooth thread is even. The thread of the shape-changed tooth can avoid the teeth slipping so that it can stop the connection from loosing. And under the same preload force, the normal force of the thread of shape-changed tooth is larger than the ordinary thread. Also the normal force are evenly distributed in the thread of shape-changed tooth. So the thread connection of the shape-changed tooth has greater frictional force. Therefore, the thread connection of shape-changed tooth is more reliable than the ordinary thread connection, and it also has more significant locking performance.更多还原