| 摘要 |
PURPOSE:To finish the outside surface of a pipe material to a specular surface by inserting the pipe material into a specular surface finishing hole die whose diameter is a little larger than a prescribed outside diameter, and applying an internal pressure exceeding the yielding point of the pipe base material into the base material hole by a pressure body. CONSTITUTION:A pipe material 1 is inserted into a specular surface finishing hole die 4 whose diameter is a little larger than a prescribed outside diameter. Movement in the axial direction of the base material 1 is stopped by pressure of a fixing member 5 of a collar part 1A, and an internal pressure exceeding the yielding point is applied to the material 1 by pushing in a pressure body 6 (mandrel). When the pressure body 6 is drawn out, the outside surface diameter of the pipe base material 1 to which a specular surface has been transferred contracts a little, and the pipe material 1 whose appearance has been finished to the specular surface is drawn out easily without being flawed. |
