It can be seen from practice that in hobbing large modulus multi tooth number gears, because of the large cutting force and cutting amount, the tool wear is more obvious, and the bad control is easy to make the tooth profile, pitch and tooth direction deviation of the gear too large, and the tooth surface roughness is not ideal, which leads to poor tooth surface contact, eccentric load and tooth profile interference phenomenon, and the machining cycle is long, especially the wide tooth surface with super large displacement and medium hard tooth surface Hobbing of large helical gear.
In the process of precise gear cutting, it is impossible to grind the cutter for hobbing because of the step difference on the tooth surface, so it is very important for the durability between the two regrinding without “tool shifting”. This is very important for the precise rolling of large module, multi tooth number and wide tooth surface, especially when the length of the cutting edge of the hob is insufficient. In order to improve the quality of the tooth surface, the efficiency of cutting and the durability of the hob, it is necessary to improve the quality of the tooth surface Take the following further process measures.
When hobbing helical gear, the rotation direction of hob should be the same as that of workpiece, and the cutting force acting on the gear blank can make the contact surface of transmission chain close without clearance. At this time, the dynamic stiffness is high, the motion stability of process system is good, and the cutting stability can ensure the machining accuracy and the quality of gear surface. A larger cutting amount can be used to make full use of the performance of machine tool and cutter, and improve the durability of hob; When the direction of rotation is opposite, the opposite is true, so the same direction of rotation hob should be selected. Because the installation angle is reduced, the length of hob and the basic processing time will be correspondingly reduced, and the axial force of hob is small, which is particularly important for super large modified gears.