Study On Dynamic Characteristics Of Gear System With Crack

Gear transmission is an important component of power and motion transmission of mechanical equipment including motor,transmission shaft,gear load etc.The overall structure is more complicated,mostly working in harsh environments,and the operating conditions are mostly high speed and heavy load,so it is very prone to fault.Gear system fault will directly affect the normal operation of mechanical equipment,and lead to machining accuracy error,production efficiency significantly reduced,even cause more serious consequences.Tooth failure caused by tooth root crack propagation is one of the most common faults.It is of great significance for gearbox condition monitoring and fault diagnosis to explore the relationship between the growth of gear crack and the dynamic characteristics of gear.In this paper,the two-stage involute spur gear is taken as the research object.By establishing an appropriate mathematical model,the numerical solution of the gear dynamic response is calculated,and the dynamic characteristics of the gear system are explored according to the characteristics of the vibration signal reflected by the faulty gear.The algorithm for box fault diagnosis and detection provides theoretical support.The specific research contents are as follows:Firstly,the structure and transmission characteristics of the gear system are analyzed.The translational torsion coupling model of the gear transmission system is established based on the lumped parameter method.The dynamic differential equation of the gear system is derived based on the meshing characteristics of the gear and the meshing stiffness.Next,the differential equations are calculated according to the characteristics of the gear system to solve the required parameters.The potential energy method is used to solve the time-varying meshing stiffness of the gear system.The crack is preset in the tooth root of the healthy gear,the time-varying meshing stiffness corresponding to the fault gear is solved,and the influence of tooth root crack propagation on the system stiffness is analyzed,and the numerical method is used for calculation.Then,the obtained parameters are substituted into the dynamic equation of the gear system to solve the dynamic response of the gear system.Set different operating conditions for the gear system and explore the effects of load and speed on the dynamics of the gear.The gear system with different lengths of cracks is solved,and the relationship between the dynamic response of the gear and the length of the root crack is discussed.The gears are pre-set with two typical faults,pitting and wear,and the dynamic response of the two faults is solved and compared with the change of the system response caused by the crack.Finally,the dynamic characteristics of gears are analyzed by frequency spectrum.The influence of crack on amplitude and frequency components of gear vibration signal is discussed.By comparing the vibration signals of gear systems with different fault forms,and analyzing the characteristics of abnormal signals to provide theoretical support for the diagnosis of gear running status.