Nippon Steel Corporation

Kouki Nanbu

Matsuo Ataka

Michio Nishikubo

Sei Miura

A metal workpiece is rolled in a rolling mill, including an upstream rolling stand or pinch rolls and more than one stream rolling stand. The roll gaps of the workrolls of the downstream rolling stand are set so that the eqivalent contact angle .theta.e (.theta.e=tan.sup.-1 (cos .alpha..times.tan .theta.) wherein .theta. denotes the contact angle between the workrolls in the bottom of the roll groove and the workpiece and .alpha. denotes the inclined angle of the groove) is larger than tan.sup.-1 .mu. (.mu. denotes a coefficient of friction between the workpiece and the workrolls at the time of biting therebetween and also is smaller than tan.sup.-1 .mu.' (.mu.' denotes a coefficient of friction between the workpiece and the workrolls when the workpiece is completely bitten between the workrolls and the rolling operation is in progress). The workpiece is fed to the downstream rolling stand by the upstream rolling stand or the pinch rolls by causing a compressive stress, which is below the yield stress at the rolling time, on the workpiece in a direction along the rolling line which is located between the upstream rolling stand or pinch rolls and the downstream rolling stand.

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Nogata, Japan

Kouki Nanbu