| 摘要 |
895,357. Cutting by spark discharge; copyturning. HALLEWELL, H. S. Sept. 14, 1960 [Sept. 29, 1959], No. 33091/59. Addition to 824,735. Drawings to Specification. Classes 83 (3) and 83 (4). A spark erosion machine having a rotary disc electrode mounted on a horizontal spindle is provided with forming apparatus as described in the parent Specification for cutting the required profile on the edge of the electrode. The forming apparatus is mounted on the bearing housing of the spindle and consists of a cylindrical stylus pin engaging a template and connected by a pantograph to a member supporting a cutter e.g. of high-speed steel, tungsten carbide, ceramic or diamond having a radiused cutting edge. The template is an exact reproduction in reverse but scaled in accordance with the pantograph ratio of the required profile of the workpiece. The stylus pin and cutter are so selected that the cutter radius is greater than the quotient of the pin radius and the pantograph ratio by an amount equal to the required spark gap. Thus using the same template and cutter by the use of different sized stylus pins, the electrode can be profiled to the shapes required for say a spark gap of 0.005 inch for rough cutting or a spark gap of 0.0002 inch for finish cutting. The electrode is of copper brass graphite or carbon or a composite structure having an electrically conducting periphery.
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