Analysis On Coupler Malfunctioning And Research On The Procedure

With further development of heavy haul transportation of freight wagons running at higher speed, issue of fatigue and damage of coupler and its parts is becoming more and more critical, which is regarded as main type of malfunctioning of the coupler. Malfunction of the coupler at the early stage not only shorten the service life of the coupler, but also threatens safety of railway transportation to some extent. Concerning the above fact, this essay will forward the proper heat treatment procedure and flaw detection procedure and initial proof for mass production procedure scheme on the basis of analysis of the reason for ineffective performance of the coupler due to fatigue and damage, further research on the principal of its ineffectiveness. Thanks to further study on common cracks of the coupler and the principal resulted in such cracks, we conclude that there are two types of cracks: one is typical surface crack, the other is internal micro crack. The primary reason for such cracks occurred on the coupler is organization defects in the process of casting and stress hot spot area generated by impact and friction damage of the coupler in the service. The study indicates that main types of damage to the coupler are adhesive damage and abrasion damage. This essay studies broken structure, the deformation resulted by the abrasive dust, maintains that the abrasive dust for the coupler in the service is generated by friction surface plastic deformation resulting in cracks'generating, expanding, dust broken. On the basis of analysis on malfunction and the principal of the coupler's part, measurements are provided by means of not changing ZG25MnCrNiMo material of the coupler but modifying heat treatment procedure enhancing features of abrasion and fatigue strength of the coupler: the knuckle and coupler body made of ZG25MnCrNiMo material is advised to be altered to Grade C steel with higher characteristic of low temperature impact ductility, then the knuckle S surface and the tail of the coupler body being handled with surface quenching method so as to enhance features of abrasion and fatigue strength. In order to prevent the fatigue broken for the coupler, extend the service life and improve reliability of the coupler and its parts, the most effective method is to implement flaw detection on the coupler and its parts besides improvement of production procedure to reduce the original crack, detect and eliminate surface cracks and other dangerous defects generating cracks to some degree in the future. Regarding to types of surface defects and analysis of the reason, the essay defines magnetic particle flaw detection with cross coils rotation magnet field technology and wet continuous procedure for inspection and measurement method for examining such surface defects. Furthermore, key points for flaw detection on the coupler are further analyzed, sensitivity of flaw detection, magnetic specification, density and cleanliness of magnetic solution and position for flaw detection are formulated. The essay also demonstrates roughly moderate frequency induce heating and quenching procedure on the knuckle S surface and tail of the coupler body, and magnetic particle flaw detection scheme on the coupler and its parts aiming at putting heat treatment procedure and flaw detection method described in this article into practice.