Search

Experimental measurement of transmission error and vibration of a gear pair with crown modification are developed. With the help of high-precision optical encoder, effects of gear misalignment on unloaded and lightly loaded dynamic transmission error, which are relative to gear rattle, are investigated. The gear mesh misalignment is introduced by eccentric sleeve assembled on the output shaft. Effects of modification and misalignment on the dynamic transmission error, are studied at different load and driving velocity conditions. The experimental results show that, with the increase of the crown amplitude, the peak-to-peak values of dynamic transmission error are decreasing dramatically. Impact deformation or elastic deformation is a very important part of the dynamic transmission error although they are unloaded or lightly loaded. The components in harmonics of meshing frequency will change distinctly comparing cases at low input shaft velocity without and with misalignment, but different phenomena are detected while increasing the input shaft velocity. Finally, the relation between transmission error and gear box vibration is illustrated, and spectrum kurtosis is introduced to reveal gear rattle. [ABSTRACT FROM AUTHOR]

The elasticity and geometrical errors of precision elements are one of the major factors affecting vibration responses in geared transmission systems. In this study, the influences of assembly error and bearing elasticity on the spur gear dynamic behavior are analyzed. A lumped parameter model for spur gear pair is formulated by representing the bearing elasticity with infinitesimal spring elements and tooth stiffness time function as rectangular waveform. The nonuniform tooth contact load is also considered. The severity of assembly error is assumed to be sufficiently small such that no partial loss of tooth contact occurs. A harmonic balance method is applied to the resultant second-order partial differential equation governing the gear pair dynamic behavior. The variations of dynamic transmission error and tooth contact load with respect to mesh frequency for a set of bearing stiffness are analyzed. The influences of bearing stiffness on the dynamic transmission error are also evaluated. The variation of actual cross angle, an indicator on the tooth meshing state, is examined with respect to nominal cross angle and bearing stiffness. The analysis shows that the presence of bearing elasticity and assembly error can degenerate tooth contact significantly, and hence the appropriate specifications of bearing and mesh stiffness are critical at gearbox design stage. The analysis demonstrates that the proposed lumped parameter model can provide detailed contact information like finite element model, but it avoids finite element model’s prohibitive computation burden and can be completed easily and be computed quickly. [ABSTRACT FROM AUTHOR]

The kinematic accuracy analysis of harmonic drive (HD) is very complex since there is a compliant cup. To explicitly figure out the effects of errors on the kinematic accuracy of HD, an equivalent mechanism in kinematics of HD is proposed, in which a spatial gear-linkage with 3-R, 2-S pin, 1-P and 1-Gear pair is equivalent to the HD with single pair of teeth of flexspline and circular spline. The kinematic model/equations of the mechanism under error condition are established by means of the mechanism topological structure analysis. For multiple tooth pairs' engagement in HD with load, a similar parallel mechanism with multi-branch of the single tooth pair is then established and a compatibility equation is derived from the identical output motion caused by all branches. With the mechanism model, the kinematic accuracy/transmission error (TE) of HD can be investigated with consideration of errors and deformation caused by load. The TE effects of assembly errors and geometry errors are simulated. The FE analysis and test of a HD are conducted to validate the proposed mechanism model. The FE and test results show good agreement with the simulations', which indicates that the proposed mechanism model is reasonable and effective. [ABSTRACT FROM AUTHOR]

A numerical model is formulated to analyze the tooth contact dynamic load distribution and dynamic transmission error of a pair of spur gears under the influence of bearing elasticity and gearbox assembly errors. In the proposed model, the deformation of the tooth is computed by applying a combination of finite elements and contact mechanics. The elasticity of the bearings is represented with infinitesimal linear spring elements, while the shafts and gears except the teeth that are in engagement are assumed to be rigid bodies. Applying those assumptions, three sets of highly coupled governing equations representing the meshing teeth flexible behavior, gear-bearing assembly translation dynamics and gear rotation dynamics are derived. The resultant model is then used to predict the dynamical behaviors of the geared rotor system, tooth contact dynamic load, and dynamic transmission error. A set of parametric studies is also performed to analyze the gear dynamic response. [ABSTRACT FROM PUBLISHER]

A numerical method to analyse the influence of assembly error on spur gear tooth contact load distribution considering bearing elasticity is formulated. In the proposed approach, a set of transformation matrices are used to define the deviation in tooth geometry orientation from the ideal position due to the bearing elasticity and assembly error. To calculate the gear tooth deflection, the theory of contact mechanics is applied to determine the micro deformation field at the surface layer of the contact region, while the finite element model is used to represent the bulk deformation in the rest of the gear structure. An efficient search strategy for obtaining the true contact points of the deformed tooth is employed. In this strategy, the tooth contact load distribution is determined based on the smallest distance between each pair of candidate contact points within a cross-section of the mating teeth, and as well as the corresponding force and moment balance conditions. Finally, the proposed model is applied to analyse the effect of assembly errors defined at eight circumferential positions on the tooth deformation in a geared rotor system comprising of four elastic bearings. [ABSTRACT FROM AUTHOR]