Discussion on the impact performance of three-dimensional clearance of gears
In the Load Contact Analysis (LTCA), the deformation of the gear teeth themselves and the support system must be considered, taking into account edge contact and multi-tooth meshing. To this end, the deformation of the support system causing the relative positional change of the meshing tooth surface is first converted into an equivalent gear pair mounting fine adjustment amount V, H, J. Where V is the fine adjustment of the vertical offset of the gear pair, H is the nominal axial installation position of the small wheel, and J is the fine adjustment of the nominal installation position of the small wheel along the axial direction of the large wheel. According to the tooth contact analysis (TCA), the angular displacement transmission error $Hra is determined, and then the Wing bending deformation $Hrb is determined by the WestingHouse cantilever beam formula according to the assumed load distribution, and the contact deformation $Hrc is determined by the Hertz formula, then the i-th pair of teeth The total transmission error is $Hri=$Hra $Hrb $Hrc(6) The inter-tooth load distribution must satisfy the angular displacement coordination principle Mn1 Mn2 , Mnk=Mn$Hr1=$Hr2=,=$Hrk(7)Mni=RliFicosAti( 8) where k is the number of simultaneous meshing teeth; Mn is the torque on the driving axle; Rli is the radius of the i-th pair of teeth meshing; Fi is the normal load of the ith pair of teeth; Ati is the i-th pair The angle between the normal load of the tooth meshing point and the tangential direction.
Simultaneously solving equation (6) (8), the normal load of each pair of teeth can be obtained. According to the above method, the gear contact analysis of a vehicle hypoid gear is carried out under light load and load condition. The gear teeth parameters are as follows: modulus 10mm, small gear teeth number 6, large gear teeth number 38, large wheel tooth width 48mm, offset distance 38mm, helix angle 49.52b, size wheel pressure angle and 45b, small wheel torque 2500Nm. The light-loaded and loaded hypoacoustic gear contact area patterns at 500Nm, 1500Nm, and 2500Nm are the unloaded transmission error curves of the pair of meshing gear teeth, the current meshing gear pair, and the exiting mesh gear pair.
Quasi-hypoid gear impact-dynamic contact characteristics Hypoid gears often exhibit initial velocity shock during starting and shifting, and sudden load shocks occur during loading. The numerical simulation of the above impact is carried out by applying the finite element hybrid solution of the impact-dynamic contact problem. The numerical simulation of the gear initial velocity impact set the small wheel to impact the large wheel with n1=1000rPmin and n2=1500rPmin respectively. The curve of the impact of the tooth surface of the hypoid gear with time is given. When the two gears impact at the initial velocity, the impact time is independent of the initial velocity, and the impact force is proportional to the velocity. The value of the gear sudden load impact simulation will occur when the gear is loaded. The small wheel is equipped with T1=1250Nm and T2=2500Nm respectively to impact the passive wheel. The load contact analysis shows that the load ratio of the maximum load gear teeth is 95.27 and 78.52 respectively. The variation of the tooth surface impact force with time of the spur gear and the helical gear in the double-tooth meshing state is given. When two rounds of sudden load impact, the impact time is independent of the load size, and the impact force is proportional to the load. It takes a short time for the load to pass from the active surface to the contact area. Therefore, after the sudden load is applied, the tooth contact area is not There was an immediate impact, but a slight lag.
Due to the presence of the flank clearance, the impact of the gear teeth (a) E1 = 0.1 mm (b) E2 = 0.3 mm (c) E3 = 0.5 mm. The impact force curve of the hypoids under different lateral gaps with time There is a certain lag, and the lag time increases as the backlash increases. When the load is applied, the gear teeth not only bear the sudden impact load, but also bear the impact load generated by the initial velocity and the initial acceleration caused by the backlash. Compared with no backlash, it can be seen that the impact force of the gear teeth is greatly increased, and the impact time is greatly shortened. As the backlash increases, the gear impact force increases rapidly and the impact time decreases slightly. It can be seen that the flank clearance has a great influence on the dynamic performance of the gear when the sudden load is impacted. In the production practice, the value of the flank clearance should be strictly controlled, and the load starting should be strictly limited during operation. The hypoid gear tooth loading contact analysis program can intuitively obtain the shape of the tooth contact area and predict the meshing performance of the gear pair under load. When the gear first impact and the sudden load impact, the impact time is related to the gear design parameters. Regardless of the initial velocity and the load size, the gear impact force is proportional to the initial velocity and the load. This shows that the energy conversion of the teeth during the impact is reflected by the impact contact force. The flank clearance will cause a lag in the tooth impact process, and the lag time increases as the backlash increases.
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