| 摘要 |
<p>PURPOSE:To solve a deviation of a thickness of a blank pipe, and to execute a pipe rolling of a good quality having no partial thickness by controlling a draft position and a revolving speed of a caliber roll of a stand of the last rear for elongating and rolling substantially the blank pipe which has inserted a mandrel through the inside. CONSTITUTION:In a mandrel mill 10 for making a blank pipe 11 through which a mandrel 12 brought to a reciprocating motion by being held by a retainer 13 has been inserted, pass through plural stands 1-8 provided with caliber rolls 1a-8a and elongating and rolling it, rolling reductions DELTAP7, DELTAP6 in two stands of the stand 7 of the last rear for elongating and rolling substantially said pipe and its previous stand 6 are measured by load cells 7c, 6c, and also based on a diameter of the mandrel 12 in this position, a deviation of a thickness of the blank pipe 11 is derived. A draft position required for solving said deviation and a revolving speed of the kaliber rolls 6a, 7a are calculated by an operation control device 20, correcting signals DELTAX6, DELTAX7, DELTAR6 and DELTAR7 are sent to the stands 6, 7, and screw down devices 6b, 7b and a caliber roll driving part are controlled.</p> |
