Mutually-different Tooth Surface Modification Method And Contact Characteristics Of Noncircular Face Gear

Noncircular face gear is a new type of gear which skillfully combines face gear and noncircular gear.It greatly simplifies the design,manufacture and exchange of spatial noncircular gear.However,the shape of its tooth surface is relatively special,and it is easy to have partial tooth eccentric load and edge contact problems in the transmission process,which seriously restricts the development and application of noncircular face gear.Therefore,this paper proposes a method for modifying noncircular face gear based on machine tool adjustment parameters,and studies the meshing characteristics of the modified noncircular face gear,which is of great significance for improving the performance of noncircular face gear.On the basis of clarifying the transmission principle of noncircular face gear and referring to the modification method of circular gear,a method of modifying mutuallydifferent gear surface based on gear shaper envelope was proposed.Based on the basic principle of gear meshing,a tooth surface model of modified noncircular face gear including machine tool adjustment parameters was established.The correctness of the model was verified by three-dimensional tooth surface simulation,which laid a theoretical foundation for subsequent meshing characteristics analysis of modified tooth surface.By establishing the geometric contact model of the modified noncircular face gear,it is obtained that the shape and position of the contact track on different gear teeth are different.The local gear teeth located in the middle position of the transition from pitch curve to the extremum of diameter are prone to partial load due to the influence of the meshing position.Based on the proposed rotary projection tooth contact analysis method,it is found that the position of the contact trace on the tooth will shift to the inside or outside diameter with the change of the modification parameters.Compared with the offset modification parameters,the axial modification parameters have more influence on the contact trace.The larger the pitch curve diameter of the gear tooth is,the greater the influence of modification parameters on the offset degree of the contact trace.Based on the contact analysis method of the loaded tooth surface,the static load meshing model of the modified noncircular face gear was established.The analysis results indicated that when the axial intersection angle parameter,axial parameter is positive,or offset parameter is negative,the contact stress on the tooth surface will decrease;On the contrary,the contact stress on the tooth surface will increase.The smaller the eccentricity of noncircular face gear,the closer the contact stress of different gear tooth surfaces is.On the contrary,the contact stress of different tooth surfaces is more different.According to the gear shaper machining principle,the NC simulation machining of the modified noncircular face gear was completed,which proved the consistency between the cutting model and the design model.A test device was built to test the rolling of the modified noncircular face gear.The contact impressions obtained were basically consistent with the theoretical analysis results,which indirectly verified the feasibility of the modified method of noncircular face gear based on the adjustment of gear shaper parameters.