Meshing Impact Of Hypoid Gear And Its Effect On The Root Crack

The difference between hypoid gears and spiral bevel gears lies mainly at the offset of the pinion,and it is also why the hypoid gears can be used to transmit power and motion between alternating axes.Besides of the transmissioncharacteristics shared with spiral bevel gears like steadiness,efficiency and high bearing capacity,a hypoid gear set has some unique advantages because of the pinion offset.Thestiffness of the pinion grows as itsradius increases,moreover,when the transmission ration is large enough,a two sides support of the gears can be achieved as the strength of the gear set would be extended.A hypoid gear set is always used in a key systemin working environment of high speed and heavy load,which would lead to higher meshing stress.So the analysis of hypoid gear set transmission characters and the prediction of root crack growth can be an active guide to the designing,manufacturing and use of it.The root cracks of gear are one of the key points of gear fatigue failure,while the research of this problem has seldomreached the field of meshing impact.Also,the complicated geometry characteristics of hypoid gears lead to some difficulties in its 3D modeling process,a precise and efficacious model must be accomplished before the above analysis begins.Based on the problems mentioned above,this paper has mainly achieved the following tasks.(1)A new method of modeling the pinion is proposed based on Boolean operation and the 3D Model of the gear set is achieved.Based on the common hypoid gear machiningmethod and the meshing theory of gears,the geometry parameters of gear blanks and the coordinate values of points on gear teeth surface is computed by the MATLAB software,also the 3D model of gears set is accomplished by using the parameters above in Pro/E 3D modeling software.Moreover,a new method of hypoid gear set 3D modeling is proposed based on the geometry feature of the gear and the Boolean operation of 3D modeling software,with this method,a gear set is modeled,too.(2)The kinetic characteristics of hypoid gears as well as the influence factors of engaging force have been researched.A finite element modeling(FEM)is established in the software of Adams and the engaging force is analyzed.The effect of friction,angular velocity and load on engaging force has also been worked out.Moreover,the stress of temporary impact is studied.From the result we can see that the meshing impact intensity increases as the revolving speed grows,while it decreases as the load heightens.The effect of friction is small.(3)The effect of meshing impact on root bending stress and root crack is analyzed.A static finite element contact model of the hypoid gear is developed in ANSYS and the root bending stress is computed.The torque load of the pinion is simulated in Adams for the calculation of bending stress under impact.The effect of meshing impact on root bending stress and root crack is revealed that the meshing impact obviously affects the root bending which can be twice the value of static stress as the revolving speed reaches a certain level.