Experimental Research On Cold Thread Rolling Parameters

With the development of the industry of automotive, aerospace,construction machinery and other industries，the market demand of threadedparts is unprecedented,and the requirement of its accuracy and strength isimproved. Thread rolling method，which has prominent advantages in terms ofmechanical properties, processing efficiency, was widely used in the threadprocessing into production.Hence,the related research has also becomepopular.In support of the National Natural Science Foundation funds，ShanxiProvince scientific and technological project Fund and Shanxi Province YouthScience and Technology Research Fund,a lot of research work in the theory ofthread rolling and rolling process simulation were done by the researchers fromTaiyuan University of Science and Technology.Through analysis of roll forming principle and the motion relationshipbetween billet and roller,the thread rolling parameters were obtained.Accordingto the rolling parameter setting method in the actual production,it took Spindlemotor speed,rollers radial feed speed and finishing time as the factors oforthogonal experiment,which could Direct regulation through the rollingmachine CNC system,to analyze their impact on thread diameter, billettemperature and work-hardening capacity.Experiments show that spindle speed is primary for thread diameter,finishing time is secondary and rollers radial feed speed is the smallest.For billettemperature rise,the biggest influence is Spindle speed,rollers radial feed speedis in the next place,the minimum influence is finishing time.For work-hardeningcapacity-maximum hardness and the thickness of the hardened layer,the biggestinfluence factor is rollers radial feed speed followed by Spindle speed andfinishing time is the last one.Combining the optimal parameters of the variousindicators with significant relationship of factors,it is determined that feed speed30mm/min, spindle speed400r/min and finishing time2s is the optimal rollingparameters in accordance with the principle of overall balance.The comparative analysis on the microstructure of the rolling thread at different spindle speedshow that the metal flow lines at the junction of thread root and the tooth side ismore smother with high spindle speed than that with low one. because highspindle speed could diverse the surface metal better,Thus contributing to threadtooth forming.This is to explain the experimental results from the microscopicpoint of outer diameter.The research of this subject would provide theoreticaland experimental basis for the rational design of rolling parameters in theproduction practice, it has a theoretical and practical significance.