| 摘要 |
<p>For an extrusion die in which a mandrel ring is fitted around a spindle, the anchoring stability of the mandrel ring is improved and maintenance is made easier. In the extrusion die, a mandrel (30), which shapes the inner surface of the extruded material, has a spindle (32) and a mandrel ring (35) fitted around said spindle (32). The base material of the aforementioned mandrel ring (35) is made of a material having a smaller coefficient of thermal expansion than that of the spindle (32). The outer circumferential surface (32a) of the aforementioned spindle (32) and the inner circumferential surface (35a) of the mandrel ring (35) are configured so that there is a gap between the two (32, 35) at normal temperature when the mandrel ring (35) is fitted around the spindle (32), and so that the gap will disappear and the two (32, 35) will touch at least at one part in the axial direction of the mandrel (30) when at the die temperature during extrusion.</p> |
