Abstract: In a rolling method of rolling a material by front-stage rolling mill, a post-stage rolling mill and guiding rollers interposed therebetween. At first, a gap between the guiding rollers is set to a standard outer size of a standard material to be rolled by front-stage rolling rollers, and a standard embracing force formed by the guiding rollers at the gap is measured when the standard material passes therethrough. Then, a machine is operated, and a post outer size of a rolled material rolled by post-stage rolling rollers is measured. The post outer size of the rolled material is compared with a desired outer size of the rolled material. In case the post outer size of the material is smaller or greater than the desired outer size of the material, an embracing force of the guiding rollers during a rolling is compared with the standard embracing force. Then, the rollers are adjusted so that the post outer size of the material becomes the desired outer size.

Abstract: In a roller guide apparatus for guiding a steel material to be rolled into a rolling mill machine, a ratio (K/M) of an elastic constant (K [N/mm]) of the roller guide portion of a roller guide apparatus to a gradient (M [N/mm]) in a plasticity characteristic curve obtained when pressing the steel material nipped between the guide rollers in rolling is determined to be 0.5 or more, to thereby prevent the steel material from tilting between the guide rollers. As a result, dimensional accuracy in sectional shape and size of an end product can be improved, and miss-rolling can be prevented, thus producing high-quality rolled steel products without surface defects with remarkably high yield rate and productivity.

Abstract: A high-rigid type guiding device for guiding a steel material to be rolled comprises guide rollers toughened by satisfying the condition in which rigidity (K) at contact portions with the steel material is defined by:K=Fmax/Smaxwherein, Fmax represents the maximum load exerted on the guide rollers (Fmax=m.times.FT, 1.0.ltoreq.m.ltoreq.2.0), and Smax represents the maximum allowable value within a range in which increment S of a roller gap defined between the contact portions is determined (Smax=n.times..delta.1, 0.2.ltoreq.n.ltoreq.0.8). Consequently, the efficiency of rolling and the productivity of the rolled steel products can be improved, and the yielding efficiency and quality of the products can be heightened.

Abstract: A four-roller type sizing mill apparatus for forming round steel rods, comprises two four-roller mills each having two pair of facing rollers. One pair of facing rollers is arranged in rolling direction perpendicular to the rolling direction of the other pair of rollers. The two four-roller mills are arranged in line, with the rolling direction of one of the two four-roller mills being shifted by 45.degree. from the rolling direction of the other four-roller mill. The two pair of rollers of a first four-roller mill positioned closer to the rolling material inlet are separated from each other by a distance which is greater than zero and not greater than five times the projected contact length of one of the pair of rollers positioned closer to the rolling material inlet.