Study on high-efficiency cutting of high-thickness workpiece with stranded wire electrode in high-speed wire electrical discharge machining

摘要

To further improve the technological indexes of high-speed wire electrical discharge machining (HS-WEDM) under conditions of high energy and high thickness while also solving the problem of an absent liquid medium and unsteady processing in the inter-electrode gap, a new type of stranded wire electrode used in HS-WEDM was designed to enhance the flow of the liquid medium and debris removal during the machining process. First, a simulation model of the inter-electrode gap flow field is established; the simulation analysis indicates that the capacity of carrying liquid medium with a stranded wire electrode is approximately 65% higher than with a normal wire electrode at a high workpiece thickness of 400mm. Next, the special discharge characteristic of stranded wire electrode is summarized from the two aspects of effective discharge area and high-thickness workpiece. Third, a comparative experiment on cutting a high-thickness workpiece at high energy demonstrates a greater threshold of stable cutting speed (over 250mm(2)/min) and stable material removal rate (142mm(3)/min) at an average cutting current of 18 A with a stranded wire electrode, whereas the maximum cutting speed (155mm(2)/min) at an average cutting current of 8 A with a normal wire electrode. Experiments prove that using a stranded wire electrode can significantly increase cutting speed and improve processing stability in the electrode gap under high-energy and high-thickness conditions.