| 摘要 |
PURPOSE:To eliminate the need for the crushing operation of the tip part of the shape after extrusion by a press by performing the forming with a mandrel and die hole after extruding from the die hole the billet bottom part by inserting the mandrel into the hollow billet with a bottom. CONSTITUTION:The bottom 3 of a billet 1 is charged into a container 11 toward a die 10 and the tip 13 of a mandrel 12 is inserted into a hole 2 so as to abut to the bottom 3. A ram 17 and the mandrel 12 are moved in the same stroke by an extruder, the bottom 3 is pressed to the die 10 by moving the container and mandrel 12 and extruded with holding the shape as the bottom directly from a die hole 16. The mandrel 12 is then moved together with the ram 17 and inserted into the die hole 16, and the billet 1 is formed in the prescribed sectional shape by the die hole 16 and mandrel 12. The mixture gas 15 of an inert gas and oxygen is blown into an extruding from 20 from the nozzle 14 of the tip 13 through the hollow part of the mandrel 12 this while, the generation of a hydration film on the inner face of the form 20 is limited and a precise oxide film is formed.
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