In order to improve the bending strength of the small gear root, the heavy contact area is usually designed to the large gear top (small gear root) area to improve the bending fatigue strength of the small gear.However, it is easy to form edge contact at the top of large gear teeth and heavy indentation at the root of small gear teeth.
In order to solve the above problems, the tip of the small wheel is made into a convex form, which can cut the material close to the working area of the root part of the tooth while ensuring a smooth transition of contact stress from the root of the tooth to the working area.
It is found that the amount of trimming is too large and the meshing impression is far away from the top of large gear teeth, which wastes high teeth. The amount of trimming is too small and the top of large gear teeth generates edge contact. Therefore, proper trimming parameters should be selected so that the meshing impression can be spread over the tooth surface with minimum contact stress and minimum bending stress of the root.