Design of thread surface finish using ultrasonic-aid in electrochemical leveling

Abstract

An effective manufacturing process using ultrasonic energy transmitted into the electrolyte to assist electrochemical leveling as a finishing operation of thread surface following thread cutting is developed. In the current experiment, four types of mating electrode are completely inserted and put through both continuous and pulsed direct current while another four types of feeding electrode are used with continuous direct current with axial electrode feed applied. The controlled factors include the chemical composition and concentration of the electrolyte, electrolyte temperature, flow rate of electrolyte, and initial gap width. The experimental parameters are die material, current density, current rating, rotational speed of workpiece and tool electrode, electrode feed rate, on/off period of pulsed current, frequency and power level of ultrasonics, and electrode geometry. For the mating electrodes, an electrode with a thin plate form provides more sufficient discharge space, which is advantageous for finishing. The electrode with a thin plate on one side has the best finishing effect. For the feeding electrodes, a thin plate form electrode of one side of the borer tip has the best finishing performance in the current investigation. Pulsed direct current can slightly improve the finish effect, at the expense of increased machining time and cost. The electrochemical leveling after thread cutting requires a shorter time than manual or machine polishing to make the thread surface smooth and bright. The average effect of the ultrasonics is better than the pulsed current while the machining time need not be prolonged by the off time.