| 摘要 |
PURPOSE: A preliminary forming apparatus for an engine valve is provided to prevent the concentration of current to specific parts of an anvil and an anvil electrode. CONSTITUTION: A preliminary forming apparatus for an engine valve comprises an anvil electrode(11), a first split electrode(13a), a second split electrode(13b), a compression cylinder, and a first insulating material. The anvil electrode has an anvil(12), and a round bar shaped work piece(14) is set between the anvil and the split electrodes. The compression cylinder applies fixed pressure to one end of the work piece. The first insulating material is located to block a relatively short current flow path between one side of the anvil electrode and the work piece in order to maintain constant length of current flow path.
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