| 摘要 |
1,240,142. Making tube billets; rolling; continuous casting. MANNESMANN A.G. 28 June, 1968 [28 June, 1967; 30 March, 1968; 5 April, 1968], No. 31036/68. Headings B3A, B3F and B3M. A tube billet for the production of seamless tubes is made by continuously casting a hollow ingot having an outer to inner diametral ratio between 5 :1 and 2:1 with a wall thickness of at least 150 mm. and an inner diameter of at least 80 mm., subdividing the continuous casting to produce ingots such that the resultant billet length will correspond to the input length of the tube production process and, after descaling, converting the cast structure of the ingot to a rolled structure by rolling without ovalization. The casting is cooled such that the segregation zone is spaced from the inner and outer walls of the casting by at least “ of the wall thickness and is furthest from the wall at which the greatest rolling deformation will take place. The descaling may be by means of steam or pressurized water on the inner surface of the ingot or carried out during the rolling of the ingot. The rolling is preferably carried out in a three, or more, roll skew rolling mill. |
