| 摘要 |
PURPOSE:To manufacture a titanium hollow shell without internal defects by controlling the heating temp. and elongation ratio of a base material to be pierced within a specified range in the case that a titanium billet is pierced with a press roll piercer. CONSTITUTION:It plays an important role in the prevention of defects of the hollow shell to make the heating of billet to be pierced at a proper temp. Therefore, the heating temp. of a square solid billet is specified at 950 - 1,250 deg.C to prevent the generation of defects inside the hollow shell after piercing and to remove cause that outside surface flaws are made by pressing scale which is generated on the billet during heating into the outside of tube with a caliber roll. And, since titanium is a hard-to-work material, when the elongation ratio is taken too large, the generation of defects is brought on the hollow shell after piercing. From this point of view, the upper limit of elongation ratio is limited <=2.5. The hollow shell without defects can be manufactured by making the heating temp. and a elongation ratio proper. |
