Analysis Of Static And Dynamic Characteristics Of Beveloid Gear And Rack

The transmission mechanism of involute beveloid gear and rack can modify the clearance axially.Although the beveloid gear is studied extensively,there are few research of clearance axial modification and crown modification.In this paper,the static meshing characteristics are studied by finite element analysis when considering the clearance axial modification and crown modification.The dynamic characteristics are analysed after building the model.The main content of article is as follows:1)Based on the meshing theory of gear,the models are establishing after the tooth surface equations of beveloid gear and beveloid rack are derived,as well as the limitations about the undercutting at large end and teeth pointing at small end of beveloid gear.2)Aiming at the characteristic that beveloid gear and rack can change the clearance axially,the relationship between axial displacement and clearance axial modification is derived,establishing the finite element model and analysing the static meshing characteristics after clearance axial modification.The results show that influences to static meshing characteristics depend on torques directly,clearance axial modification has large effect on uniform degree of contact stress when torque is large and static transmission error when torque is small.3)Aiming at the problem that there is clear edge contact of beveloid gear and rack after clearance axial modification,the static meshing characteristics are analysed after deriving the crown modification theories of beveloid gear and rack.The results show that crown modification can decrease the influences of edge contact effectively,but the top value of contact stress,bending stress,static transmission error and contact force increase with the increase of crown modification value.The influences of gear angle error to static meshing characteristics decrease with the increase of crown modification value.4)The dynamic characteristics of beveloid gear and rack are analysed by Adams after establishing the dynamic model.The results show that average speed of gear gradually increases,dynamic contact force and fluctuation amplitude of gear angular acceleration gradually decrease after increasing the value of axial modification or teeth of gear,indicating that above adjustments can make the operation of mechanism become more smooth.After increasing the value of cone angle,rotation speed of gear does not change regularly,dynamic contact force and fluctuation amplitude of gear angular acceleration increase,indicating that increasing the value of cone angle is not benefical to make the operation of mechanism become more smooth.Angular acceleration of gear changes periodically with frequency,fluctuation period is close to 62.8Hz,about 100 times the gear rotation frequency.