AGMA 07FTM17-2007 pdf free.Simulation Model for the Emulation of the Dynamic Behavior of Bevel Gears.
The main source for the dynamic excitation of bevel gears is the tooth mesh [1]. In the tooth contact different excitation mechanisms are combined to a complex resulting excitation. The three most sigriificant terms are the unloaded transmission error, the changing stiffness of the meshing teeth and the premature tooth contact, Figure 1.
The load-free transmission error is caused by gear deviations which lead to a path excitation [3]. The most important gear deviations influencing the excitation behaviour under load-free operating condition are pitch, flank and profile variations [4]. [5], [6]. But path excitations can also be caused by devations of 3rd order, as e.g.. generated cut deviations and even of 4th order, as e.g.. roughness describing tooth flank surface structures 17]. All deviations lead to changing operating conditions. i.e., changing rotational speeds and different load carrying torques. In numerous practical tests it is shown that for operation conditions of low specific loads deviations have the main influence on the excitation in the tooth mesh and on the noise.
The second excitation mechanism in the tooth contact results from changing stiffness of the meshing teeth as the number of teeth in contact changes. This mechanism named as parametric excitation causes additional vibrations for operation conditions under load. The domination of the parametric excitation increases by higher load carrying torques [8].
A further excitation mechanism in the tooth mesh can be traced back to the premature tooth contact, [9J. Under loaded operating conditions the teeth and the gear body are deformed. This leads to disturbed kinematic contact conditions in the tooth mesh. Consequently, the first tooth contact occurs earlier than under undisturbed conditions and the driving tooth flank penetrates theoretical the driven tooth flank. Out of this results a tooth impact and a force impulse is generated combined with an additional sound stimulation.
Fundamental procedure
At first, the manufactured flank topography must be determined in consideration of the manufacturing process, and further of the prescribed quality respectively the prescribed flank modifications. The flank topography can be determined with a generally kept approach for the description of machine kinematics of bevel gear cutting machines 1101. The method simulates the manufacturing process by following the penetration of the single tool cutting blades through the material. The tool geometry and the chosen machining parameters can be considered. Based on the geometries of the pinion and the gear resulting from the manufacturing process FE models are generated in the next step.
To reach an exact reproduction of gear properties the use of a high-grade computational approach, as the Finite Element Analysis (FEA), is necessary. But the formulation of the contact conditions is problematic in the Finite Element Analysis. since it is a non-linear problem. FEA is suitable for solving the stiffness of gears but the modelling of the tooth contact is a very difficult task. Hence an FE based tooth contact analysis is used. This FE based approach uses the structure properties of an FE model and combines them with a simple mathematical spring model to examine the tooth contact conditions [11], Figure 2.AGMA 07FTM17 pdf free download.