In the research of tooth profile modification, the influence of tooth profile modification on the strength of gear teeth is generally not considered.In this section, based on the dynamic meshing force simulated, the influence of profile modification on the strength of gear teeth is qualitatively analyzed.Since the amount of modification is small and only the top modification is considered, the strength of the teeth of the modified gear and the non-modified gear at each engagement position is basically the same with the meshing force unchanged.
In the process of gear transmission, the forces acting on a single tooth can be divided into two situations: the first is single tooth engagement, in which case the dynamic engagement force of the gear is applied on a single tooth; the second is double tooth engagement, in which case the dynamic engagement force is shared by two adjacent teeth, in which the force acting on a single tooth is the dynamic engagement force multiplied by the load distribution factor between the teeth.From the above analysis, it can be seen that the force of a single gear in the process of gear transmission is obtained by multiplying the dynamic meshing force Fm(t) by the load distribution factor Lsf(t) between the teeth:
Under linear modification, the length of modification is 2.8mm and the time-domain curve of single tooth stress is shown when the modification is 0.006mm and 0.014mm respectively.It can be seen from the diagram that in the single-tooth engagement area, the force on the single tooth of the modified gear increases, which means the strength of the gear teeth decreases; in the double-tooth engagement area near the single-tooth engagement area, the force on the single tooth of the modified gear decreases, which means the strength of the gear teeth increases; in the middle area of the double-tooth engagement area, the force on the single tooth of the modified gear increases, which means that the strength of the gear teeth decreases..As the amount of modification increases, the strength of the teeth decreases gradually in the single-tooth engagement area and the double-tooth engagement middle area, while the strength of the teeth increases gradually in the double-tooth engagement area near the single-tooth engagement area.
Under linear modification, the modification quantity is 0.026mm and the time-domain curve of single tooth stress is shown when the modification length is 2.8mm and 7mm respectively.It can be seen from the diagram that, compared with the non-modified gear, the long-modified gear reduces the force of single tooth and increases the strength of the teeth only in the vicinity of the top position of the teeth, while in the remaining areas, the force of single tooth of the long-modified gear increases and the strength of the teeth decreases.At the same time, with the increase of the modification length, the force of single tooth gradually decreases in the single-tooth engagement area and the middle area of double-tooth engagement, and the strength of the teeth gradually increases. In the double-tooth engagement area, the force of single tooth gradually increases and the strength of the teeth gradually decreases in the area near single-tooth engagement.
Based on the above analysis, it can be seen that the influence of tooth profile modification on the strength of teeth at different engagement positions is greater. The strength of teeth in the middle of single-tooth engagement area and double-tooth engagement area decreases for SHORT-TOOTH modification, while that in other engagement positions increases; while the strength of teeth in long-tooth modification decreases only near the top of the teeth.With the increase of modification quantity or the decrease of modification length, the strength of the teeth in the single-tooth meshing area gradually decreases.