Abstract: Sheet bars are effectively joined while they are traveling and subjected to continuous hot rolling without causing defects in quality and without requiring large expensive apparatus such as a swing roller etc.The present invention is to provide a continuous hot rolling method and apparatus in which the tail of a preceding sheet bar is butted to the top of a succeeding sheet bar between the rough and finishing mills on a continuous hot rolling line, and the butted portion is welded from the upper surface of the sheet bars by means of laser beam or plasma arc while the sheet bars are traveling.According to the present invention, it is possible to join sheet bars from the upper surface in a short period of time without stopping the sheet bars and without causing splashes and burrs, before the sheet bars are subjected to continuous finish rolling.

Abstract: An axially symmetric ring work piece is formed by a warm or hot, forward and backward extruding, die forging system. In this system, a die having a rearwardly projecting portion, which projects in the opposite direction to a pressing direction, a heated work piece, and a punch having a forwardly projecting portion, are arranged, in that order, in a container. A withdrawal die is arranged between the container, and the heated work piece, the die and the punch. The die is fixed so that a die velocity V.sub.D is 0, and the punch is moved toward the die while a punch velocity V.sub.P is set to be twice as large as a withdrawal die velocity V.sub.WD and the strokes of slide of the withdrawal die are not less than one-half of a forward-extruded foot length of a product. Thus, the forward and backward simultaneous extrusion can be substantially performed in a single-action type, short-stroke, die forging system.

Abstract: Sheet bars are effectively joined while they are traveling and subjected to continuous hot rolling without causing defects in quality and without requiring large expensive apparatus such as a swing roller etc.The present invention is to provide a continuous hot rolling method and apparatus in which the tail of a preceding sheet bar is butted to the top of a succeeding sheet bar between the rough and finishing mills on a continuous hot rolling line, and the butted portion is welded from the upper surface of the sheet bars by means of laser beam or plasma arc while the sheet bars are traveling.According to the present invention, it is possible to join sheet bars from the upper surface in a short period of time without stopping the sheet bars and without causing splashes and burrs, before the sheet bars are subjected to continuous finish rolling.