Mesh Characteristics Of Hypoid Gears With Face-hobbed Method

With the requirement increased of high efficiency and low cost,the method of the face hobbed to processing of hypoid gear is becoming more and more popular.However,the disadvantage with tooth surface forming theory,tooth surface design,calculation of machine setting and contact area adjustment because continuous indexing and full processing method.According to the above key problem,the paper base on the actual processing for hypoid gear and the structure of cutter plate and machine and the machining theory,the mathematics model of hypoid gear with the face hobbed method.On the basis of the model,the influence of tool errors and installation misalignment on tooth surface geometry and meshing characteristics was researched.For optimistic designing of cutter,meshing quality and increasing the service life,it has both the theoretical and project practical significance.The main contents of this dissertation are shown as follows:(1)Based on the actual processing for hypoid gear,the mathematics model of cutter plate in based on the ND normal direction and the tooth surface for face-hobbed hypoid gear by HFT(Hypoid Formate Tilted).The parameters of tool errors and the direction of tooth surface deviation is definition.Thereafter,the solid model of hypoid gear with the face hobbed method was established.The influence of tooth surface geometry on tool errors is analyzed.The results show that the impacts of and pressure angle on the tooth surface deviation are very obvious and spheric radius error is not obvious.The deviation tendency of regrind angle,cutting side relief angle and the rake angle errors is basically similar and the influence of the regrind angle is strongest and the rake angel is the weakest on the geometric morphology deviation of tooth surface.(2)A whole mechanics model of axle including hypoid gear is established by MASTA.Based on the mathematics model of hypoid gear and the finite element analysis method(FEM),the transmission meshing model of hypoid gear is built.Furthermore,the gear misalignment under the two conditions of theory and preset box eccentricity was calculated.The results show that the preset box eccentricity misalignment can help to reduce the misalignment.The contact pattern is move up slightly and the edge contact will be happened under the premise of misalignment.With the load increase,the phenomenon of edge contact will be obvious.Compared to standard installation,the maximum contact stress is strongest and the area slightly is reduced.The transmission error peak-to peak value is strongest.Compared to normal misalignment,the influence of contact pattern is not obvious and the transmission error peak-to peak value is slightly reduced(3)The influence of tool errors on meshing characteristics is analyzed.The results show that the effect of spheric radius is slight and pressure angle of reference point on tooth surface geometry are mostly obvious and the rake angle is smallest;the pressure angle of reference point and the regrind angle have the same influence on the location of the contact pattern,but the impact of the pressure angle of reference point is stronger;the effect of rake angle and cutting side relief angle on contact pattern is insensitive and the influence of the cutting side relief angle on the mean value of the transmission error is greater than the rake angle.(4)The experimental study on the cutting machining that adopt to C27 CNC machine and tooth surface detection are performed.The theoretical tooth surface parameters are obtained and compared with the calculated tooth surface point set,which verify the correctness of tooth surface mathematical model.The rolling test is performed for hypoid gear to obtain the contact pattern and theoretical theory result by TCA and LTCA in KIMOS,which are compared with the finite element calculation.The results show that the location and area of contact pattern by TEM is consistency with theoretical design contact pattern by KIMOS.The transmission error is closer to the measured result by rolling test.Thus,its verify the correctness of the tooth surface.