Flow Field Design and Experiments on Pulse ECM of Large-lead Ball Nut Raceway During Tool Cutting-out Stage

Abstract

A novel process of pulse electrochemical machining (PECM) using a spherical tool cathode with inner slant jet has been proposed and preliminary verified for the machining of large-lead ball nut raceway, in which the electrolyte flow field uniformity plays a very important role in achieving high machining accuracy and process stability. This paper is focusing on the flow field design during tool cutting-out stage, which is considered necessity for realizing one-pass PECM of raceway. Difficulties of flow field design lie in the nonuniform flow field distribution caused by the sudden change of electrolyte flow and the possible deformation or movement of the spike. The method using sacrifice metal was adopted and two novel types of fastening way (the welding type and the magnetic attraction type) were presented to solve the problems existing in conventional methods using sacrifice metal. Verification experiments were conducted and the results show that stable PECM can be achieved using these two types of method. It's also found that the magnetic attraction type of method has better performance of process stability and adaptability than that of the welding type.