No abstract

As aerospace requirements for low noise and high strength spiral bevel gear transmission continue to increase, tooth surface precise control is becoming increasingly important in design and manufacture. The previous design depended significantly on ease off the tooth surface and using the tooth surface optimization approach. It’s a parameter design technique that goes from the design tooth surface to the target tooth surface without accounting for the reaction of the tooth surface to machine tool machining errors. This study proposes a new algorithm for reverse adjustment of tooth face accuracy control. A mathematical model of the tooth face is initially built using the local synthesis method to replicate the genuine machining process. Second, the machine setup settings are chosen as multi-objective optimization parameters, and the reverse adjustment model is constructed to investigate the machine’s machining error on the tooth surface, as well as the reverse adjustment model’s effects on contact and robustness characteristics. Finally, numerical calculations and comparisons with the findings of existing design approaches are used to verify the validity and effectiveness of the reverse adjustment algorithm in the design of tooth surface accuracy control of curved bevel gears.

The vibration and noise of marine power systems mainly comes from gearbox in addition to engine, while gearbox vibration is mainly caused by internal excitation of gear transmission system (GTS) and transmitted to ship hull through the box. This paper proposes a vibration reduction method of 3D modification controlling the strength of vibration source and constrained damping structure restraining vibration transmission energy. For herringbone gear,The 3D modification form of tooth surface combining with two parabolas and one straight line is proposed and the modified tooth surface equation is derived based on the principle of forming grinding.Combined with tooth contact analysis (TCA) technology and loaded tooth contact analysis (LTCA) technology, three internal excitations of GTS after 3D modification are determined. Through force balance and node connection relationship between each element, the coupling dynamic model of gear-shaft-bearing with three internal excitations i.e., time-varying meshing stiffness, transmission error and meshing impact is established to calculate dynamic load of journal bearing.The load is loaded into the finite element model of the gearbox to obtain its vibration value and six symmetrical pressing plates are applied force to fix the foundation with adding the same constrained damping structure in the middle.The purpose of reducing gearbox vibration is realized by combining 3D modification technology with constrained damping structure.The results of numerical examples show 3D modification can effectively reduce the radial and axial vibration of the gearbox, while the constrained damping structure can availably cut down transverse vibration. Compared with modification, constrained damping structure is more obvious effect. This study will contribute to the in-depth study of vibration reduction measures of marine gearbox system under variable excitations, and analyze its vibration characteristics under different vibration reduction measures, so as to meet the requirements of its vibration reduction and realize safety and stability of ship hull.

The VOF (volume of fluid) multiphase transient simulation model of the windage loss of the gear pair under oil-jet lubrication was carried out by using the dynamic mesh technology with the powerful parallel computing capabilities of the Super Cloud Computing Center. Firstly, a two-phase (oil-gas) turbulence numerical model was established in the process of oil-jet lubrication. The numerical simulation test was designed by orthogonal experiment. The influence of the oil-jet lubrication parameters and their interaction on the windage power loss was studied by means of variance analysis. The results showed that the influence of injection speed on the windage power loss was the largest and proportional, followed by injection temperature and injection pressure, and the latter two factors were inversely proportional. Then, the fitting calculation formula of windage loss related to each influencing factor is obtained based on the numerical simulation results. Furthermore, by observing the velocity vector distribution of the internal flow field of the gearbox with different time, the formation mechanism of windage loss is understood intuitively, and the measures to reduce windage loss are put forward. Finally, the mechanical and energy characteristics of the windage loss under different oil injection parameters are proposed, by analyzing and calculating the differential pressure force, viscous force, turbulent kinetic energy, and turbulent dissipation rate around the gear pair. This paper provides a method guidance for the calculation of windage power loss and efficiency of aviation gear pair under elastohydrodynamic lubrication in engineering application.

With the continuous improvement of the requirements of spiral bevel gear transmission for low noise and high precision, the optimization of high-efficiency tooth surface accuracy considering the motion axis error of machining machine tool has become a key point in the process of designing and manufacturing spiral bevel gear. Based on the theory of the multi-body dynamics system and the principle of gear meshing, a new tooth surface error model of spiral bevel gear considering the error of machine-tool moving axis is proposed and optimized, so as to obtain higher tooth surface accuracy and meshing efficiency. Firstly, according to the motion and machining principle of spiral bevel gear NC grinding machine, the corresponding relationship between the motion error of each axis of the NC gear grinding machine and the variation of cutting parameters of spiral bevel gear is analyzed, and the geometric motion error model of spiral bevel gear grinding machine is given; secondly, the tooth surface equation of the spiral bevel gear considering the machine-tool motion axis error is established; then, in view of Powell's dog leg optimization algorithm, the tooth surface considering the motion axis error of the machine tool is optimized, and the optimal cutting parameters of spiral bevel gear tooth surface machining are obtained. Finally, the simulation results show that the difference between the peak and peak values of transmission error and the maximum contact stress of the tooth surface is reduced by 72.6% and 1.62%, respectively, and the meshing efficiency is improved from 0.9798 to 0.9803 after optimization; by comparing the rolling experiment and simulation results, the maximum error between the quantitative parameters of the two groups of tooth surface contact marks is no more than 9%, which verifies the effectiveness and feasibility of this method, and provides a certain theoretical basis for practical production and processing.