To provide a surface glass forming material with which operation is performed safely and the generation of internal defects of a billet is prevented when performing the hot expanding/piercing of the hollow billet, and a method of manufacturing a billet for tube making.
(I) This surface glass forming material includes a ring-like glass forming part 6 and a ring-like projection part 7 mounted to the opening part 8 of the glass forming part. In the ring-like projection part, it is preferable that the thickness (ii) of a ring is 5-20 mm, the outside diameter is smaller than the inside diameter of the hollow billet by 1-10 mm, and the length (iii) in the height direction of the projection part is 5-20 mm and the thickness (iv) of the ring-like glass forming part is 10-35 mm. Furthermore, the surface glass forming material is chamfered in the upside of the opening part of the ring-like glass forming part and it is preferable that this angle (v) is 10-20 to the vertical line. (II) The method of manufacturing the billet for tube making is a method using the glass forming material and by which above effects are obtained.
YAMAKAWA TOMIO
MATSUMOTO KEIJI
MURAKAMI KOSUKE
| JP2005000927A | 2005-01-06 |
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