中文摘要：

针对运用中偶有发生的转K2型、转K4型、转K6型3种货车转向架变刚度弹簧组的断簧问题进行计算分析。试验载荷下的寿命估算表明；质量完好的这3种转向架变刚度弹簧组的各型弹簧的疲劳寿命均可达到3×10^6次；其中，转K2型转向架的减振内簧、转K4型转向架的减振外簧、转K6型转向架的承载外簧在对应的弹簧组中相对寿命较短。疲劳校核表明；转K2型、转K6型转向架各型弹簧能基本满足疲劳强度要求，校核结果与寿命估算所得的结果一致；转K4型转向架弹簧的校核结果与其所采用的试验方案有关系，现行试验方案下，校核所得的转K4型转向架减振外簧的疲劳强度相对最弱。分析认为，应该修正减振内簧的设计参数，从设计源头消除失稳及由此引发的其他问题；个别弹簧出现折断质量问题，主要原因是弹簧钢材质不够稳定，材料与产品的热处理工艺匹配不够完善。建议立项研究60Si2CrVAT材料的基础性能参数。

英文摘要：

The spring fracture problem accidentally happened on alter-rigidity spring combinations of Zhuan K2 Zhuan K4 and Zhuan K6 bogie is analyzed. The life estimation indicates under the experiment load that every spring＇s fatigue life on alter-rigidity spring combinations of Zhuan K2 Zhuan K4 and Zhuan K6 bogie made ideally can achieve 3× 10^6 cycles. The life of the damping inner spring of Zhuan K2 bogie, the damping outer spring of Zhuan K4 bogie and the bearing outer spring of Zhuan K6 bogie in their combinations is relatively shorter. The fatigue evaluation indicates that every spring＇s fatigue strength of Zhuan K2 and Zhuan K6 bogie can meet requirement. This result conforms with the life estimation. The evaluation result of Zhuan K4 bogie is relative to the adopted experiment method, and the fatigue strength of the damping outer spring is the weakest under the new method. The analysis shows that the design parameter of damping inner springs should be revised for eliminating losing stability and other problems from design phase. Some spring fracture cause is mainly instability of spring steel quality, and the arts and crafts on heat treatment of steel material matching spring product is necessary to be perfected. Advice about studying foundation parameter of 60Si2CrVAT material is given for competent department.