Rupture Analysis Of K2 Type Bogie Springs

In recent years, along with the leap-over advancement of railway industry, all spring-manufactured factories have made much improvement in technical equipments, quality-control system and craftwork, etc. which greatly increased the quality of spring product and provided a technical assurance for prolonging the assurance period of spring product quality. Presently, the whole industry is under supervised of Specifications for Helical Springs on Rail Freight Car Bogie in which the quality assurance period for helical springs is 9 years (a works repairing period) and fatigue test cycles are 3 million.K2 type interior helical spring is one of the important fittings on K2 type bogie for freight car. Therefore, it is critical to improve spring quality. However, the fails of spring such as rupture, wearing, erosion, slackness and deformation are often seen. It is obvious that damage resulted from the rupture of spring during operation is the most serious in above mentioned fails.Analyses to strains and stresses on K2 type springs show that K2 interior helical spring bears most of the forces in the four spring types for which the article choose K2 type interior helical spring as emphasis to study. It is found through analyses to basic performances of springs that material diameter d and spring center diameter D are the two factors which affect performances of springs most.Through analyses to spring material, the paper shows that material defect is the main reason that affect the fatigue life of springs which means inspection to spring material in manufacturing process is so strict that any unqualified material can not be put into use. Through analyses to material preparation, forging, rolling and heat-treatment, the paper presents several factors (heating temperature, amount of material in each furnace, quenching temperature, choosing of medium, temper temperature,etc.) Affecting the fatigue life of springs, which are clearly regulated in manufacture techniques.Through analyses to reinforcement treatment and surface treatment, the paper shows that sound reinforcement and surface treatment can prolong the fatigue life of springs, which is also clearly regulated in manufacture techniques.Through analyzing example of K2 type interior helical springs, the paper presents two main factors, which influence the fatigue life of springs-----springmaterial and manufacture process. Considering the above factors, to increase the life period of springs, there must be reasonable and proper manufacture techniques and it must be followed.In the end, the paper discussed the manufacture techniques for K2 type interior helical springs to ensure the fatigue life of springs.