A Precision Machining of Gears. Slow-Scanning Field Controlled Electrochemical Honing.

Abstract

This paper presents a new working method of controllable Electro-Chemical Honing (ECH) of gears as follows. A gear shaped cathode which is meshing with a workpiece gear during machining is exposed as cathode pole only on a strip on the tooth dank. By varying the center distance between the cathode and the gear slowly, the electrolysis zone sweeps over the tooth flank from root to tip (slow scanning as we call it). Since the center distance is varied by a step motor, so the time of dwelling of the pole, and hence the amount of metal removal on different spots of the profile can be controlled by programming. An on-line profile error measuring device is provided. The computer calculates the required discharging time which has a relationship with dwelling time, and sends out the programming to control the metal. removing rate so as to cancel the error or to produce profile correction needed by silent transmission. A mathematical model is built for calculating the required discharging time. Several ground gears with typical profile errors are subjected to trial machining on this working principle. It cancels the profile errors very efficiently. The experiment demonstrates that the machining method can step up the profile accuracy to very high order on the basis of the general accuracy guaranteed by the proceeding operationgear grinding.