METHOD AND MEANS FOR INTRODUCING A MANDREL INTO A TUBULAR BLOOM

1,248,834. Rolling mills. MANNESMANN A.G. 4 Sept., 1969 [6 Sept., 1968], No. 43738/69. Heading B3M. A mandrel 1 is rapidly fed by rollers 3 into a hot hollow billet 7 while the billet is moved slowly towards a continuous rolling mill 12. The speed of introduction of the mandrel is controlled so that the mandrel and billet are moving together, at the same speed as the first stand of the mill, as they enter the stand. The degree the mandrel extends from the leading end of the billet as the mandrel enters the mill is controlled according to the reduction to be made to the billet. The billet is intially fed from a lateral conveyer 6 on to rollers 10, the rollers then being raised until the billet is held in driving engagement between rollers 10 and 11. The rapid acceleration of the billet by the rollers 3 is helped by electromagnets 4 which pull the mandrel towards the rollers. Adjacent electromagnets are of reversed polarity, and a demagnetizing ring is provided, in order to prevent magnetization of the billet. The speed of the various rollers is controlled by a computer in response to signals from an infra-red position detector 5, a photo-cell 8, and displacement measuring devices 13 and 14. A lubricant spray device 15 is provided for the mandrel.