Analysis Of Anti-looseness Properties And Optimization Design Of Variable Thread Nut

Any kind of mechanical connection is made of many components in a certain way, and thread connection is the most common kind of joint. Nowadays, with the development of modern mechanical equipment which feature is high-speed, heavy-load and precise, thread loosen will reduce the reliability of mechanical equipment. Once thread connection looses, it will cause serious consequences. There are so many traditional threaded connection methods, some of which is reliable, but sometimes, is very complicated, or re-use is bad, or the anti-looseness properties is not reliable, or the structure can not withstand high-speed operation and the strong impact. In order to effectively solve loosen and fracture problems of the thread connection, foreign scientists proposed a new type of nut which is called variable thread nut.According to loosening reason of the thread, we can conclude that the anti-looseness properties of the nut mainly depend on the force and deformation of the threads. What’s more, the anti-looseness properties of the nut can be improved by changing the pitch of the nut. By analyzing the force and elastic deformation of the common bolts, nuts and screw threads, this paper summed up the anti-looseness principle of the variable nut in theory. Compared with the traditional common thread structure, variable pitch thread can be achieved by cutting the single side of the nut thread teeth, which could improve the load distribution between the threads, and reduce the amount of deformation between the screw threads, in order to improve the anti-looseness properties. Also, using the advanced finite element software, we can analysis quantitatively the anti-looseness properties of the variable thread nut. Through anglicizing the stress distribution, the deformation distribution, the changing trend of the remaining preload and the micro slip of the thread, and comparing the data with the standard nut, we can summed up that the of the variable thread nut is superior to standard nut’s. Finally, optimizing the pitch parameter by APDL language, this paper designs the optimal model of variable thread nut.Variable thread nut has many advantages. Improving the anti-looseness properties of the thread connection and the reliability of mechanical equipment by changing the pitch of the thread, it makes a great significance to engineering practice.