| 摘要 |
PURPOSE:To extremely reduce the tube wall thickness and to prevent damage to the tube surface by pressing an annular stock between a die and an anvil and pushing up a mandrel to work the stock by utilizing the friction force between the mandrel and the stock. CONSTITUTION:A gap corresponding to a tube wall thickness of products is formed between a hole of a die 3 and a mandrel 2. Both an edge roundness and a length of the roundness of the die 3 are reduced and an annular stock 1 is pressed between the die 3 and an anvil 4 through a die stem 6. In that time, the pressing is performed by pushing up the mandrel 2 by a subram of a press. A tube product 1a having an extremely thin wall is obtained because a smoothly finished surface without slips and seizings is formed by fully utilizing the friction force on interface between the mandrel 2 and the stock 1. Therefore, the tube wall thickness is extremely reduced and damage to the tube surface is prevented.
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