Nippon Steel Corporation

Other

Samon Yanagimoto

Minoru Kawaharada

Seishiro Yoshiwara

Susumu Mizunuma

Koshiro Aoyagi

Shuji Nagata

Motoaki Sugiyama

Fujimasa Koyama

Kouki Nambu

A press roll piercing method wherein a polygonal billet is pushed in the axial direction thereof between a pair of driven rolling rolls mounted one above the other and a piercing plug is supported in the center of the pass by a mandrel, is improved by selecting a pushing force of a predetermined value which corresponds to a stress above the yield stress of the billet at the starting of the piercing although the actual stress occurring at the starting of the piercing may or may not exceed the yield stress by selecting the pushing speed and/or the peripheral speed of the rolls such that the volume of the billet pushed in per unit time and the volume of the hollow shell discharged from the rolling rolls become substantially equal, whereby the billet is positively gripped by the rolling rolls.

Press roll piercing method

In the rolling of metallic material by using a rolling mill having a working roll for each surface of the workpiece reduced and having the shafts fixed with respect to movement in the direction of travel of the workpiece, the workpiece is rolled at such a high reduction rate in cross-sectional area that the contact angle .theta. between the working roll and the workpiece can have a value of .gtoreq. tan.sup.-1 .mu. (.mu. being the coefficient of friction between the working roll and the workpiece), and the rolling operation is carried out by pushing the workpiece between the working rolls, so that a neutral point of relative movements between the rods and the workpiece wire remain within the surface along which the working roll and the workpiece contact each other. The rolling apparatus has a device to push the workpiece between the working rolls and a rolling mill or rolling mills of high reduction capacity to roll the thus pushed workpiece at a high reduction rate of the cross-sectional area, whereby there can be rolled strip, bar, wire rod shape, beam blank or the like in a limited number of passes.

Method and apparatus for rolling metallic material

A metal extrusion process with high reduction wherein a metal blank is extruded from a container through an opening which is formed by a plurality of work rolls. The metal blank is guided to the opening from the outlet of the container by causing the metal blank to adapt to the shape of the opening by means of a forming die so that the metal blank does not overfill the opening. This extrusion process is capable of forming the metal blank into a product having the desired cross section with high elongation in one pass and also the radius of curvature of the corner portion of the product can be freely adjusted.

Metal extrusion process with high reduction

A method of producing a cylindrical metallic tubular body in a press roll piercing mill. The method involves applying a pressing force to a polygonal metal billet in the axial direction thereof while guiding the billet by means of a guide during its advance, rolling corner portions of the billet to a certain degree with a pair of rolling rolls having semicircular grooves disposed above and below the billet prior to the contacting of a plug with the center of the front end surface of the billet, and successively piercing the billet by means of the plug while the billet is rolled, the tip portion the plug being retained on the pass center line by the rolling rolls.

Method of producing tubular body in a press roll piercing mill

In a method of producing seamless steel tube from billet having a square or rectangular cross-section by the step of piercing a workpiece and rolling steps following the piercing step, each of such steps being conducted with a plug held by a mandrel toward the center of cross section of the workpiece while the workpiece is rolled by a pair of rolls with axes arranged horizontally. The piercing step includes guiding the workpiece by a plurality of pairs of guide rolls provided along the rolling line ahead of the rolling rolls as the billet is forced therethrough to maintain the billet in such a position that the hollow shell will not have any nonuniformity of wall thickness and piercing workpiece with a plug as the workpiece is pushed and inserted between the rolling rolls under the forced guidance by a pushing force working in the axial direction, and as the plug progresses into the center of cross section of the workpiece, so as to pierce the workpiece, thereby producing seamless steel tube having very little nonuniformity of the wall thickness.

Growing community of inventors

Kitakyushu, Japan

Samon Yanagimoto