Krosakiharima Corporation

Joji Kurisu

Arito Mizobe

Hiroshi Otsuka

Koji Kido

Masahide Yoshida

Takahiro Kuroda

Kento Furukawa

Masaki Yamamoto

Hisatake Okumura

Tetsuo Tsuduki

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

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.

Immersion nozzle for continuous casting

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

Joji Kurisu