Thread Cold Rolling Simulation And Experimental Study

In recent years, the technology cold rolling of thread technology was rapidly developed due to its high efficiency, low cost and perfect properties of its production. Few studies were carried out on the cold-rolling technological theory and the mechanical analysis of the precise forming both at home and abroad. Therefore, the research on the cold rolling of thread has important theoretical and practical value. It can promote the application of this non-cutting methord to be more popular.In this paper, the cold thread rolling process and theory were analyzed. The rolling process was divided into four stages according to the amount of feed of the thread rolling dies.The numerical simulations on the rolling process of solid parts were carried out with DEFORM software. The stress field, strain field, velocity field in the workpiece were got.In the experiments the microstructure, hardness and hardened layer, and several other areas were compared. The force of cold rolling thread was obtained by numerical simulation.And the theory of cold rolling thread was verified.Through the analysis and the comparation of the microstructure, hardness and hardened layer and residual stress, we conclude that: The microstructure of Cold rolled thread was crushed, grain boundaries become blurred, and the cutting threads were cut off, metal structure did not change significantly. the surface hardness of cold-rolling thread was better than cutting thread. Hardness of cold-rolling thread which was treated after heat treatment can reach 330HV, in contrast before heat treatment can only reach 220HV. The hardened layer of the cold-rolled thread have a certain depth in normal direction, otherwise, the hardness of the thread cutting have no diversification; cold rolled thread surface area have a continuous fibrous structure, and the microstructure was refined. The structure property and the suface hardness of thread which is rolled after heat treatment is better than cold rolled before heatment.The conclusion provides the theoretical basis for the further research of the cold rolling technology and practical operation. It has a theoretical significance and practical value.