Two-dimensional tool design for two-dimensional equilibrium electrochemical machining die-sinking using a numerical method

摘要

Electrochemical machining (ECM) can be defined as controlled electrolytic anodic erosion. ECM can machine hard alloys and metals with tools of softer metals, without affecting either workpiece microstructure or surface properties. There is no tool wear owing to a lack of tool/workpiece contact. The ECM medium between the tool and workpiece is electrically conductive, causing the finished workpiece geometry to vary from the tool and not to become a direct inverse of the tool shape. The characteristics of the workpiece material can also affect shape transfer, increasing the difficulty of designing and simulating ECM tools. At present, ECM tool design in industry is a trial-and-error process that can be prohibitively time-consuming. Automated design and simulation procedures are, therefore, desirable. This paper describes a computational approach to ECM tool design for two-dimensional cases based on the solution of a set of ordinary differential equations in a basis function format that are based on the electric field during the ECM process. This method has a number of advantages. It allows for the use of geometric representations of the tool and workpiece, such as B-Splines and Bezier curves. This enables easy integration with most current computer-aided design software. It is also possible more easily to design and simulate tools for non-ideal machining conditions, where parameters such as electrolyte conductivity vary with the ECM cell. Above all, this method can design tools directly for the ECM process, given a particular workpiece shape without iterative methods. Computational trials have been carried out and compared with the results of an experimentally validated model. These showed that the method was effective for tool design under ideal machining conditions and was easier to use for non-ideal condition modelling.