Research On Bolt Cold Forming Process And Influencing Factors

Research of this subject focuses on three important procedures of minitype bolt cold forming process–drawing, preforming and finish-forming. Parameters such as strain and stress fields in the forming process can be solved with nonlinear finite element analysis, and the influencing factors can be quantificationally analyzed by design of experiment and data processing.By nonlinear finite element simulation, the special feature of stress, strain fields and material flow pattern of typical drawing process can be gotten. A new model formula of the pressure on the surface of drawing tool working area is brought forward and solved, and the drawing force model based on this new model is compared with the old experiential formula. The influence of each influencing factor on strain, strain rate and drawing force is quantificationally analyzed. These researches can provide a lot of useful imformation for the design of drawing process parameters.The preforming process of minitype bolt is compared with the one of common bolt, and the differences of the parameters such as stress, strain, damage and flow pattern are analyzed. A model of minitype bolt preforming force is put forward and solved, and it can be used in the design of preforming die. The capability of minitype bolt prefoming process is studied. The influence of each influencing factor is quantificationally analyzed too.For the research on final-forming process, the influence of different preforming process on final-forming quality is analyzed, and a judgement standard of finial-forming quality is schemed out. Based on this standard, the quality of final-forming can be judged and the preforming shape is graded. The law of good performing shape is summing up. Aiming at the shortage of minitype head forming die structure, a new structure is worked out. The influence of each influencing factor on typical final-forming process is quantificationally analyzed finally.Through all of these researches above, the three forming procedure of minitype bolt forming process are understood deeply. This subject is significative for the manufacture of minitype bolt.