| The planetary gear transmission system is widely used in many types of industrial equipment due to its high transmission ratio,good bearing support conditions and low noise.As their long-term working environment has higher requirements for speed,performance and use life,the diagnosis of gear faults and the detection of surface wear degree have become urgent and important factors for industrial equipment.Tooth surface spalling fault is the most common mode of gear failure.Using condition monitoring techniques,the degree of gear damage can be monitored,and the healthy operation of the equipment was ensured.This work aims to solve the problem of spalling fault of planetary gearboxes.Firstly,the dynamic modeling was researched to obtain the variation law of the dynamic behavior for planetary gearboxes.Then,the experiments were conducted to verify above research,and to acquire the reliable data support for subsequent vibration signal analysis and surface topography analysis.Finally,the health condition monitoring of planetary gearbox can be realized.This article has made research from the following aspects.(1)For the planetary gearbox,geometric models of healthy gears(including internal meshing pair and external meshing pair),and a tooth surface spalling model of planetary gear(sun gear side)were established.The stiffness calculation formula of the gear was deduced,and the effect of different spalling degrees on the meshing stiffness was studied.At the same time,considering factors such as time-varying meshing stiffness,composite mesh error and backlash,a dynamic model of the planetary gearbox transmission system was established,and the influence of tooth surface spalling fault on the system’s vibration response was analyzed.(2)The spalling fault was processed on planetary gears.And the basic test group and three groups of different degrees of spalling fault gear tests were conducted,and vibration signal data were collected.Secondly,according to the advantages of fast curing,low shrinkage and low thermal expansion of the copy film,the correct film model was selected to acquire the surface topography of the gear tooth surface without disassembling and destroying the gear.Which provides data support for subsequent wear studies.(3)The time-varying filtering empirical mode decomposition(TVF-EMD)method was applied to the fault diagnosisof planetary gearbox.Aiming at the shortcomings of the TVF-EMD,the sample entropy was used as the fitness function,and the gray wolf optimization algorithm was used to optimize the core parameters to obtain the optimal combination solution.Multiple weight indexes were used at the same time to accurately select the optimal the Intrinsic Mode Function component,and to accurately identify the failure frequency characteristics of the planetary gear.The correctness of the dynamic model of the tooth surface spalling fault and the practicality of the proposed method were verified by the comparison and analysis of the test signal and the simulation dynamic response.(4)The prepared tooth surface film samples were observed using the white light interferometer.More detailed analysis of the evolution process of the tooth surface with different degree of damage was carried out,and the tooth surface profile characteristic image was obtained.Two-dimensional(2D)images were partially magnified,and the evolution processes of micro-pitting,pitting and spalling on the tooth surface in different tests were analyzed.In addition,the three-dimensional(3D)images were analyzed.The surface roughness of the filming samples for the gear tooth under different test conditions were obtained intuitively.At the same time,the tooth surface area was divided and the surface roughness of different sub-area was analyzed.From the view of more microscopic and stereoscopic,the gear wear can be observed and the failure process of the gears can be comprehensive analyzed. |
