Abstract: The present invention provides a rolling method and apparatus for manufacturing concrete-reinforcing steel bars, wherein the invention provides for obtaining various concrete-reinforcing steel bars satisfying the required specifications for knot height while using the same finishing rolls even if the diameters of the final product steel bars are different. According to the present invention, two pairs of rolls (total of four rolls) each having a roll caliber and one or more knotting round calibers are used for the final finishing pass, and the two pairs of rolls are arranged to exert rolling pressures in two orthogonal directions on a raw material S.

Abstract: An apparatus for guiding various sized round steel bars to calibers of rolls while stably holding the round steel bar. The round steel bar can be securely prevented from being twisted with a small amount of a holding force, so that a product with a desirable and accurate dimension can be manufactured. The guide apparatus comprises guide rollers installed at the inlet of at least one of a plurality of multi-roll sizing mills, each stand of which is composed of at least three rolls disposed in a line. The method of guiding the round steel bars comprises a step of elastically holding the free or unrolled surface portion of the round steel bar with a press force in the range of approximately 100 to 500 kg. With the round steel bar guide method and apparatus, a round steel bar is pressed and elastically held on the free surface of the guide apparatus.

Abstract: In a plural-roll rolling mill having a pass line arranged by the respective sets of rolls, each having a caliber formed on the outside peripheral surface thereof, the outside peripheral surfaces being disposed close to each other, the calibers of the rolls being cut with a cutting tool of a three-dimensionally (forward and rearward, rightward and leftward and upward and downward) movable cutting machine. The rolling mill, which has a reference column disposed on the outside surface thereof at a position spaced apart from the pass line by a predetermined distance, is removed from a rolling line and fixed, and the positional alignment of the cutting tool is carried out by causing a contact sensor disposed on the cutting machine at a position spaced apart from the cutting tool by a predetermined distance to come into contact with the reference column. With this arrangement, there are provided a method and apparatus capable of cutting the rolls of the plural-roll rolling mill while mounted on the rolling mill.

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.

Abstract: A cellulose triacetate film excellent in both of the tear strength and the folding endurance can be obtained by casting a cellulose triacetate dope using a solvent mixture of methylene chloride with the other solvent in a ratio of 13 to 25 wt. % of the total solvent weight on a support of which the surface temperature is kept lower than 10.degree. C., and drying with controlling the drying conditions so that the content of volatile components in the film and the film surface temperature enter a particular region or so that the content of volatile components in the film and the shrinkage percentage of the film in the cross direction enter in a particular region. The film thus obtained is also excellent in flatness.

Abstract: A method of rolling steel rods or wires by grooveless rolls for reducing sectional areas of the rods or wires and achieving a stable rolling operation with high efficiency by limiting to less than a predetermined value the ratio of a long side to a short side of a cross-section of a blank material (having a rectangular cross-section) which has passed through each pair of grooveless rolls or limiting the ratio of the diameter of each pair of grooveless rolls to the gap therebetween. The method of rolling steel rods or wires by grooveless rolls also achieves high elongation efficiency to make stable the rolling operation by limiting the ratio of the diameter of each pair of grooveless rolls to the gap therebetween. The method uses a grooveless roll entry guide in the grooveless rolling so as to securely hold a blank material from entry to exit in a gap between the pair of grooveless rolls to eliminate overturns at the ends of the blank material and fins extending from the material due to the overturns.