Krosakiharima Corporation

Arito Mizobe

Joji Kurisu

Takahiro Kuroda

Koji Kido

Hiroshi Otsuka

Shinichi Fukunaga

Hiroki Furukawa

Masahide Yoshida

Takuya Okada

Kouichi Tachikawa

Hisatake Okumura

Kento Furukawa

Masaki Yamamoto

Takashi Sadano

Mitsunobu Sato

Kenichi Oki

Takahiro Yasuda

Tetsuo Tsuduki

Jouji Kurisu

Hideaki Kawabe

Manabu Kimura

A flat immersion nozzle stabilizes the discharging flow of molten steel thereby stabilizing the molten steel surface in a mold, namely, decreasing the fluctuation thereof. In the immersion nozzle having a flat shape in which a width Wn of an inner hole is greater than a thickness Tn of the inner hole, a central protrusion portion () is disposed in a center section of a wall surface in a width direction of a flat section. Wp/Wn, a ratio of a length Wp of the central protrusion portion in the width direction to Wn, is 0.2 or more and 0.7 or less. The central protrusion portion () is disposed symmetrically as a pair; and a total length Tp in the thickness direction of the pair of the central protrusion portions is 0.15 or more and 0.75 or less of Tn.

Immersion nozzle

A nozzle structure for discharging molten steel with improved sealing performance. The nozzle structure comprises: a molten steel discharge path having an inner bore; and one or more joints through which the molten steel discharge path is divided at one or more positions in a orthogonal direction with respect to an upward-downward direction of discharge of molten steel, and which join the molten steel discharge path. An inner bore sleeve is formed of a refractory material, and provided on an inner bore surface of the nozzle structure to extend in the upward-downward direction across at least one of the joints.

Nozzle structure

With a view to adding, to an upper nozzle formed with a bore having a shape capable of creating a less energy loss or smooth (constant) molten steel flow to suppress the occurrence of adhesion of inclusions and metals in molten steel, a gas injection function to thereby further suppress the occurrence of the adhesion, the present invention provides a method of using an upper nozzle configured to have a cross-sectional shape of a wall surface defining the bore, taken along an axis of the bore, comprising a curve represented by the following formula: log(r (z))=(1/n)&#xd7;log((H+L)/(H+z))+log(r (L)) (n=1.5 to 6), where: L is a length of the upper nozzle; H is a calculational hydrostatic head height; and r (z) is an inner radius of the bore at a position downwardly away from an upper edge of the bore by a distance z. The method comprises using the upper nozzle in such a manner as to satisfy the following relationship: R&#x2266;4.3&#xd7;V, where Ris a gas rate defined as a volume ratio of a flow rate Q(Nl/s) of injection gas to a flow rate Q(l/s) of molten steel flowing through the bore (R=(Q/Q)&#xd7;100(%)), and Vis a flow speed of the molten steel at a lower edge of the upper nozzle.

Method for using upper nozzle

The immersion nozzle for continuous casting, including a tubular body with a bottom, a pair of first outlets, and a pair of second outlets, wherein at least a lower section of the tubular body has a rectangular flat cross section; the two opposing first outlets are disposed in narrow sidewalls at the lower section; the pair of second outlets is disposed at the bottom; each of the first outlets is partitioned by a partitioning section formed at the first outlet into an upper outlet and a lower outlet; ridges formed between the partitioning sections respectively project into a passage from a wide inner wall of the passage; the pair of second outlets is disposed symmetrically to a central axis of the tubular body such that virtual faces extended from tilted faces of the second outlets intersect with each other in the passage.

Immersion nozzle for continuous casting

Provided is a molten metal discharge nozzle capable of suppressing turbulence in a molten metal stream passing through an inner bore thereof, with a simple structure. A cross-sectional shape of a wall surface of the inner bore, taken along an axis of the inner bore, comprises a part or an entirety of a curved line expressed by the following formula: log(r(z))=(1/n)&#xd7;log((Hc+L)/(Hc+z))+log(r(L)) (1), where: 6&#x2267;n&#x2267;1.5; L is a length of the nozzle; Hc is a calculative hydrostatic head; and r(z) is a radius of the inner bore at a position located a distance z downward from an upper end of the nozzle, wherein, in a graph where the distance z is plotted with respect to a horizontal axis (X-axis) thereof, and a pressure of molten metal at a center of the inner bore in horizontal cross-section at a position located the distance z is plotted with respect to a vertical axis (Y-axis) thereof, an approximation formula of a line on the graph is established without simultaneously including two or more coefficients having opposite signs, and wherein, on an assumption that the line is derived from an approximation formula based on a linear regression, an absolute value of a correlation coefficient of the line is 0.95 or more.

Molten metal discharge nozzle

It is intended to uniform and straighten a molten steel stream flowing out of a discharge port of an immersion nozzle, and thus suppress mold powder entrapment in the vicinity of the immersion nozzle. The immersion nozzle comprises a tubular-shaped straight nozzle body formed to extend in a vertical longitudinal direction and adapted to allow molten steel from a molten-steel inlet provided at an upper end thereof to pass downwardly therethrough, and a pair of discharge ports provided in a lower portion of the straight nozzle body in bilaterally symmetrical relation and adapted to discharge the molten steel from a lateral surface of the straight nozzle body in a lateral direction. An inner surface of each of the discharge ports has, at least in part or in its entirety, a shape defined by a curved line along which an inner bore of the discharge port in a longitudinal cross-section of the immersion nozzle passing through respective centers of the immersion nozzle and the discharge port is gradually reduced in diameter in a direction from a start position to an end of the discharge port, wherein the curved line is represented by a diameter in the longitudinal cross-section of the immersion nozzle.

The present invention is directed to creating a less-energy loss or smooth (constant) molten steel flow with a focus on a configuration of a bore of an upper nozzle, so as to provide an upper nozzle formed with a bore having a configuration capable of to suppress deposit formation. For this purpose, in an upper nozzlefor allowing molten steel to flow therethrough, a radius of an upper end of a boreis set to be equal to or greater than 1.5 times a radius of a lower end of the bore, and a bore surfaceis formed in a vertical cross-sectional configuration represented by log(r(z))=(1/n)&#xd7;log((H+L)/(H+z))+log(r(L))(n=1.5 to 6).

Upper nozzle

An immersion nozzle for continuous casting including a tubular body, the tubular body having at the upper end an inlet from which molten steel is introduced into a passage extending from the inlet downward inside the tubular body, the tubular body having a bottom and being depressed in cross section at least at a lower section, the lower section having two narrow sidewalls and two broad sidewalls, the narrow sidewalls having a pair of opposing first outlets communicating with the passage, the bottom having a pair of second outlets communicating with the passage. The lower section has ridges projecting into the passage respectively from the inner surfaces of the broad sidewalls between the pair of first outlets. The second outlets are arranged symmetrically about the axis of the tubular body such that the axes of the second outlets cross each other within the passage.

An immersion nozzle for continuous casting, including (1) a tubular body with a bottom, the tubular body having an inlet for entry of molten steel disposed at an upper end and a passage extending inside the tubular body downward from the inlet, and (2) a pair of opposing outlets disposed in a sidewall at a lower section of the tubular body so as to communicate with the passage, the nozzle comprising: a pair of opposing ridges horizontally projecting into the passage from an inner wall between the pair of outlets, the inner wall defining the passage.

Disclosed is an immersion nozzle, which comprises a vertically-extending pipe-shaped straight nozzle bodyadapted to allow molten steel to pass downwardly from an inlet portprovided at an upper end thereof, and a pair of discharge portions each including a respective one of a pair of outlet portsprovided in a lower portion of the straight nozzle bodyin a bilaterally symmetrical arrangement and adapted to discharge molten steel laterally from a lateral side of the straight nozzle body. Each of the discharge portions has an inner surface defining the outlet portand extending parallel to an axis of the outlet portto define a length of the discharge portion at 45 mm or more. A ratio of S/Sis in the range of 0.8 to 1.8, wherein Sis a total transverse vertical cross-sectional area of the outlet ports, and Sis a cross-sectional area of an inner hole of the straight nozzle body taken along a plane including a line connecting respective inwardmost and uppermost positions of the outlet ports and extends perpendicularly to an axis of the straight nozzle body. The axis of the outlet port extends laterally outwardly and downwardly at the following angle &#x3b8;t with respect to a horizontal direction: 0&#xb0;&#x2266;&#x3b8;t&#x2266;20&#xb0;. The immersion nozzle of the present invention can suppress deceleration of a molten steel flow discharged from the outlet port to obtain a flow speed in an intended direction over a maximized distance.

Growing community of inventors

Fukuoka, Japan

Arito Mizobe