Large taper mechanism of HS-WEDM

Abstract

Large taper (≥ ± 5°) high-speed wire electrical discharge machining can be affected by many factors. The positioning error of wire electrode caused by guide wheels and the run-out of guide wheels are particularly important. Moreover, dielectric fluid cannot wrap the wire electrode appropriately and flow into the machining region along with the wire electrode in tilt directions. As a result, the machining accuracy and surface roughness of a large taper-cutting workpiece are worse than those of straight cutting. In order to solve these problems, this paper presents the design and improvement of two types of six-bar linkage large taper-cutting mechanisms that can realize the guide of wire electrode and the tracking spray of dielectric fluid along with the incline of the wire electrode. The first type causes angular error but no wear, whereas the second one causes wear but no angular error. The former is applied to process experiments. The experimental results show that, compared with traditional mechanisms, this new approach decreases the roundness error of the workpiece from 80 to 40 μm and the surface roughness from 4.059 to 3.495 μm under the same processing parameters. In terms of multi cutting (skim cutting), the new mechanism reduces the roundness error of taper cutting (taper ±20°, thickness 40 mm) to 25 μm and the surface roughness to 1.670 μm. An idea of intelligent servo traverse guider based on this mechanism is also proposed in this study.