Study On New Spraying Technology And Equipment For Sleepers

Cement concrete sleeper is one of the important parts in the railway laying.Its main function is to brace the rail,maintain the rail position and transfer the force from the rail to the ballast bed.Cement concrete sleeper laid in the open country is often corroded by acid-alkali-salt solution,irradiated by strong light and baked at high temperature.At the same time,the sleeper vibrates intermittently for the running of the trains.For the reasons above,cracks and pit defects are formed on the surface of sleepers,which reduces the service life of sleepers.In this paper,the idea of using epoxy resin concrete slurry as chemical inert protective coating to spray on the surface of concrete sleepers is put forward,which can isolate the sleeper surface from the external environment and maintain the original structural strength of sleepers,avoid surface defects and improve the service life of sleepers.Epoxy resin concrete slurry has high viscosity and poor fluidity,and the spraying effect of existing nozzles is not good.In this paper,an air atomization nozzle with inner spiral groove runner is proposed,and the following work is accomplished:(1)The mechanism of air atomization and the means of evaluating atomization quality are described,and the nozzle structure is designed by maximum flow method;(2)The two-phase flow field in the nozzle is simulated by using ANSYS Fluent software;(3)Experiments are carried out to determine the spray cone angle and flow characteristics of the nozzle;(4)Composite concrete sleepers are formed by spraying epoxy resin concrete slurry on the surface of cement concrete sleepers;(5)Design of automatic equipment conveying system,spraying system and control system for sleeper surface spraying is carried out.The research results are as follows:(1)In the internal flow field of nozzle,the pressure of gas inlet increases,the liquid region of nozzle decreases,and the liquid velocity increases.When the gas inlet pressure is 0.4 MPa,the atomization angle of the nozzle reaches 59° and the flow rate reaches 0.0123 L/s and the nozzle has the best atomization effect;(2)Composite concrete sleeper has uniform coating,firm bonding and good corrosion resistance,the designed nozzle solves the problems of difficult spraying of high viscosity liquid and poor coating quality;(3)Roller conveying system can safely convey sleeper to spraying station;spray nozzle can be moved in the direction of sleeper length and roller length according to the set path and speed to realize automatic spraying;PLC is used as the control system of controller to realize automatic operation of equipment.Spraying with this equipment improves the quality and efficiency of the coating.