Topological Modification Method And Realization By Form Grinding For Helical Gears Based On Functional Requirements

Helical gear is an important transmission component of automobile,wind power generation,metallurgy,mining,oil and cement industry large mechanical and electrical equipment.At high speeding operation of these equipments,the helical gears bear huge loads,which cause unfavorable displacement of tooth contact,resulting in edge contact,highly concentrated stressed,shock and vibration.This requires that the manufacturing quality of gear teeth meet the requirements of these devices running,in order to improve their service life and operational reliability.Along with the development of these devices,the gear transmission is developed in the direction of high power,high speed and heavy load,which must have high accuracy,bearing capacity and stability of operation to meet the functional requirements of the specific working conditions.Therefore,reduce the sensitivity to the installation errors,avoid the edge contact,reduce vibrations and noise and increase load capacity of the gear drives,which these functional requirements are heavy-duty helical gear manufacturing key scientific problems to be solved.In this paper,a method of topological modification with deviation feedback correction is proposed,aiming to provide theoretical guidance for the high precision grinding and transmission characteristic optimization of heavy duty helical gears.In this paper the main research results are listed as follows:Tooth micro geometry parameters optimization model is established,by analyzing the mechanism of meshing impact and dislocation quantity based on Hertz contact theory.In order to meet the functional requirements of the heavy-duty helical gears under different conditions,the dynamic characteristics of the gear pair are improved to a certain extent in the transmission error,bearing capacity,load distribution and so on.The transmission error,the contact stress and the distribution law of the meshing displacement of the gear pair with different load are studied,which provides theoretical basis for the research of the micro geometry of the tooth surface.According to the gear form grinding machine kinematics principles,a segment topographic modification method of tooth flank is presented.Profile segmented modification is achieved by changing length of involute occurrence line of invloute profile on the top and root of the tooth;longitudinal segmented modification is accomplished by attaching to a parabolic and linear radial feed motion when forming grinder is moving.The formula of topological modification tooth surface is derived,the boundary of topographic correction tooth flank has been divided and established the equations of motion for each servo axis of form grinding machine.Combining with the tooth surface of the TCA results of n?merical analysis,the distribution rule of the transmission error and tooth contact pattern of the gear pairs with different modification parameters is obtained.The profile of grinding wheel and the motion trajectory of diamond wheel truing grinding wheel is calculated based on the tooth surface topological modification CNC grinding method.Then the equations of piecewise motion of grinding wheel along the workpiece radial direction are established,and the form grinding model of tooth surface segment topological modification is presented.According to a sensitivity analysis of polynomial coefficients of axis motion and the topographic flank errors by on-machine measuring,the corrections are determined through an optimization process that target minimization of the tooth flank errors.A closed-loop feedback correction method in topographic modification tooth flank is proposed based on the gear form grinding.An on-machine topography measurement approach is proposed for topological modification helical gears on the five-axis CNC gear form grinding machine that can measure the modified gear tooth deviations on the machine immediately after grinding.The planning method of the tooth surface measurement area grid point is analyzed,and the processing algorithm of the tooth surface grid point measurement data is studied.The distribution characteristics of tooth surface deviation are obtained by means of tooth profile deviation and tooth surface deviation control chart analysis.Using the method of grey system theory and the bootstrap method,the tooth surface deviation dynamic forecast model is established,which can dynamically evaluate the tooth surface deviation under the condition of lack of information.Based on the above research,the experiment of the grinding process of the topological modification,on-machine measurement and feedback correction on the heavy duty helical gear is carried out.Off-line measurement result shows that the validity of this flank correction method is demonstrated for tooth surface deviation that is reduced.The loading experiment of gear drives with different modification parameters is carried out.The results show that the topological modification can reduce the transmission error,cut down the vibration and noise,avoid edge contact,and improve the quality of gear drives transmission.