Method and apparatus for rolling metallic material

A method of rolling a steel workpiece by using a rolling mill having opposed working rolls in a fixed position relative to the direction of travel of the workpiece and at a fixed spacing from each other, which method comprises rolling the workpiece between the working rolls while driving said rolls and continuously exerting on the workpiece a force in the direction of movement of the workpiece through the rolling mill in addition to the force exerted in the direction of rolling by the working rolls within the surface of contact of the working rolls and the workpiece and which additional force in the direction of movement of the workpiece is less than that necessary to stress the workpiece beyond its yield point under the conditions of rolling and having a value .sigma..sub.p .times. A where A is the cross-sectional area of the workpiece and .sigma..sub.p is the additional exerted force per unit area of the workpiece and is represented by:

• ##EQU9## where:
• K:
• Yield stress (kg/mm.sup.2) of the workpiece at the rolling temperature
• .theta.:
• Contact angle of the working roll (rad)
• a:
• Constant
• b:
• Constant
• C.sub.1 :
• constant
• .mu.:
• Coefficient of friction between the working roll and the workpiece
• .mu. = [C.sub.2 (1.05 - 0.0005.T) - 0.056.multidot. V.sub.R ] C.sub.3
• C.sub.2 :
• constant determined according to the material of the working roll;
• 1.0 in the case of a forged steel roll;
• 0.8 in the case of a cast steel roll
• C.sub.3 :
• constant determined according to the roll lubrication = 1 .about. 0.1
• V.sub.r :
• rolling speed (m/sec)
• T:
• rolling temperature (.degree.C)
• whereby an elongation of the workpiece is produced which is much greater than the arithmetic sum of the elongation which would be produced by the driven working rolls alone and the elongation produced by the force in the direction of movement of the workpiece alone for moving the workpiece through non-driven rolls.