Experimental Study On The Abnormal Wear Of Two Contact Strip-wire Pairs In Metro Rigid Pantograph-catenary Systems

Nowadays our country is in a period of rapid construction of urban rail transit such as subway and light rail transportations.Comparing to other urban rail transits,the metro transportation is more convenient and its traffic volume is larger.The metro has become the preferred mode of transportation for people traveling.The pantograph-catenary system is an important part in the electrified rail transit.The pantograph strip and contact wire are two important parts of the pantograph-catenary system.The wear of the pantograph strip and the contact wire directly determines the maintenance cost of pantograph catenary systems,and also becomes an important factor affecting the development of rail transits.Therefore,the research on the friction and wear performance of pantograph-catenary contact pairs is of great practical significance.In this paper,two kinds of pantograph strips and the Cu-Ag alloy contact wire were taken as the research object,and a series of tests were carried out on a block-on-ring type current-carrying friction and wear test machine to study the abnormal wear of the pantograph-catenary contact pairs.The influences of the joint gap and the joint height difference on the abnormal wear of the contact pair were studied.The friction and wear properties of different strips were compared and the optimal normal pressure for different strips was matched.The influences of the step-type joints of different strips on the wear performances of the contact pair were tested.The friction and wear properties,electrical characteristics and topography of the strips were studied,and the following conclusions can be drawn:(1)The size of the joint gap of the assembled Cu-impregnated strip A will not cause the abnormal wear of the contact pairs.The joint gap will reduce the mechanical wear to a certain extent,leaving mechanical wear scratches on the Cu-Ag alloy contact wire.However,the scratches are generally shallow,which does not affect the normal operation of the pantograph-catenary system.(2)The size of the height difference of the joint for the assembled Cu-impregnated strip A will cause the abnormal wear of the contact pairs.The height difference of the joint will scratch the copper silver alloy contact wire greatly,which will cause the wire drawing phenomenon and produce the plough groove on the contact wire surface.(3)The current-carrying friction and wear performance of Cu-impregnated strip B is slightly better than that of the Cu-impregnated strip A.Under the condition of current 400 A,normal force 80 N and speed 60 km/h,the wear of the Cu-impregnated strip B is slightly smaller than that of Cu-impregnated strip A.The temperature of the Cu-impregnated strip B is slightly higher than that of Cu-impregnated strip A.The optimal normal force for matching the Cu-impregnated strip A is 80 N.The optimal normal force for matching Cu-impregnated strip B is 120 N.(4)The Cu-impregnated strip B will cause the abnormal wear of contact pairs of pantograph-catenary systems in the condition of high currents.Under the condition of current 400 A,normal force 100 N,and speed 30 km/h,the Cu-impregnated strip B produces serious electrical erosion,accompanied by a high temperature of 600 centigrade and the irritant smoke volatilized after the adhesion agent of the contact strip was ignited.In the test,the contact strip was burned red.After the test,the surface of the contact strip was ablated into fluffy particles.(5)The step of the Cu-impregnated strip A will cause abnormal wear when Fn=80 N.It is recommended to increase the normal force to suppress it.