STUDY ON DESIGNING 3-D CONTROLLED SURFACE MICROGEOMETRY OF WORKPIECE IN METALWORKING.

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In the first part by photoetching copper sheets with varied 2-D masking patterns and by the subsequent friction test and scanning electron micrography, the geometrical conditions of cavities which exhibit effective micropool action during rubbing are made clear.In the following part of the project, a new process is developed : combining ion-beam etching of metalworking tools and the following coining process to produce surface microgeometry on the sheet surface. Ar ion-beam etching enables production of numerous microasperities on the WC-Co tool with high strength and durability to wear. To obtain deep cavities on the WC-Co tool a austenitic stainless foil of 0.1mm thick with numerous microholes(a kind of filter or mesh)is used as a mask. By installing the foil over the target flat tool at a spacing of 2 to 20mm, an appropriate slope of the cavity wall is obtained. Controlling the spacing between the target tool and the mask foil was possible by subjecting the mask foil to equi-biaxial tension by supplying a jig which contains the target tool on the head. and constructs a cylindrical flat-headed punch.The newly developed method is in principle applicable to all metals, ceramics, etc. Up to now 30mm X 30mm WC-Co block with cavities of around 50 mm is obtained.(Cavity diameter on the top is 200 mm. with pitch of 260mm)The tool is successfully applied to coining to produce reverse micro-projections on the sheet surface of copper and aluminium.