Improved hot-rolling process for sealess tubes with preliminary diameter reduction of the semifinished products

摘要

In an improved process for hot-rolling of seamless tubes with preliminary diameter reduction of the semifinished products (axially pierced round blanks), the coreless reduction step (without mandrel) occurs immediately before the step of continuous rolling on a mandrel and practically at the same time of driving the mandrel into the pierced blank, without interferences therebetween. The apparatus carrying out this operation is positioned immediately upstream of the continuous mill with mandrel, so as to form with this a single unit on the same line, thus reducing the need for room, the operation time and consequently the blank cooling before rolling, whereby the last stand of the rolling mill is reached at a sufficient temperature for rolling without any need of intermediate heating steps.