JP6206106B2 - Continuous casting roll and continuous casting method - Google Patents

Description

The present invention relates to a continuous casting roll and a continuous casting method used when conveying a continuously cast slab in a continuous casting facility.

  In the steel industry, when a molten steel is solidified to produce a slab, a continuous casting machine is generally used. As shown in FIG. 1, a continuous casting machine 1 is a continuous casting roll in which a high temperature slab 4 whose surface is solidified by first cooling with a mold 3 immediately below a tundish 2 is gradually drawn below the mold 3. Then, the slab 4 is continuously produced while being sandwiched between the slabs 5.

  In such a continuous casting machine 1, the surface of the roll body of the continuous casting roll 5 that conveys the slab 4 continuously cast from molten steel has thermal expansion when it is in contact with the high temperature slab 4; Shrinkage when not in contact is repeated, and cracks are likely to occur due to fatigue.

  For example, Patent Document 1 discloses a continuous casting roll in which a plurality of annular slit grooves are provided in the circumferential direction on the outer peripheral surface of a roll body. By providing such a plurality of slit grooves, distortion due to expansion at the time of slab contact is absorbed, and there is an effect of preventing deterioration of the roll by preventing cracks of the roll.

JP 09-192808 A

  However, when continuous casting is performed using a continuous casting roll as described in Patent Document 1, a phenomenon called sagging has occurred. As shown in FIG. 2, this is a phenomenon in which the convex portion 12 sandwiched between the grooves 11 of the continuous casting roll 5 is crushed by the slab. The portion indicated by the dotted line in FIG. 2 is the shape of the initial convex portion 12 of the roll 5, and the portion where the convex portion 12 is crushed is the outer peripheral surface 13 toward the central axis of the roll 5 as indicated by the solid line. Move and roll diameter decreases. Thus, when a roll diameter changes locally, there exists a problem that the quality of the slab cast continuously falls.

An object of the present invention is to provide a continuous casting roll capable of preventing cracking due to thermal stress from a slab and preventing a local decrease in roll diameter, and a continuous casting method using the continuous casting roll. There is to do.

In order to solve the above problems, the present invention is a continuous casting roll used for transporting a continuously cast slab, and a plurality of circumferential grooves are formed on the surface layer of the roll over the entire width direction, The groove formed in the range of 650 mm to 750 mm in the center in the width direction of the roll has an R dimension of 2 to 4 mm, a groove depth of 15 to 30 mm, a groove width of 2 to 6 mm, and a groove pitch of 10 at the groove bottom. The groove formed on both ends of the roll in the width direction has a R dimension of 30 to 40 mm, a groove depth of 2 to 8 mm, a groove width of 20 to 24 mm, and a groove pitch of 50 mm. A continuous casting roll characterized by being a shallow groove of ˜70 mm is provided.

Further, the present invention is a continuous casting method for transporting a slab using a continuous casting roll, wherein the continuous casting roll has a plurality of circumferential grooves formed in the entire width direction on a surface layer of the roll. The groove formed at the center in the width direction of the roll is a deep groove having an R dimension of 2 to 4 mm, a groove depth of 15 to 30 mm, a groove width of 2 to 6 mm, and a groove pitch of 10 to 30 mm. The groove formed at both ends in the width direction of the roll including at least the portions in contact with both ends in the width direction of the slab of the smallest dimension has a R dimension of 30 to 40 mm at the bottom and a groove depth of 2 to 8 mm. The present invention provides a continuous casting method characterized by being a shallow groove having a groove width of 20 to 24 mm and a groove pitch of 50 to 70 mm.

  According to the present invention, a deep groove that sufficiently absorbs strain due to thermal expansion at the time of slab contact is provided in the width direction center portion where cracks are likely to occur, and both ends in the width direction that are easily crushed by the slab, By providing a shallow groove having high rigidity, both cracks and local reduction in roll diameter can be prevented, and roll deterioration can be suppressed.

It is a side view which shows the outline | summary of the continuous casting machine concerning this Embodiment. It is sectional drawing explaining the sag of a roll. It is explanatory drawing of the part which is easy to generate | occur | produce the roll sagging. It is a front view which shows the example of the roll for continuous casting concerning this Embodiment. It is sectional drawing to which the cross section of the A section of FIG. 4 was expanded.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 shows an outline of an example of a continuous casting machine 1. Molten steel in the tundish 2 is poured from the upper side of the mold 3, and the slab 4 in a state where the surface is solidified by the primary cooling by the mold 3 is gradually pulled out from below the mold 3. Below the mold 3, the slab 4 is continuously fed out while being sandwiched between a plurality of pairs of continuous casting rolls 5 disposed facing each other, whereby a continuous slab 4 is produced.

  As a material used for the continuous casting roll 5 used in such a continuous casting machine 1, for example, the roll body is heat-resistant steel, and the surface layer thereof has heat resistance, wear resistance, and corrosion resistance. A surface layer portion covered with a built-up layer of a Ni—Cr-based material provided with The roll 5 for continuous casting has a roll diameter of, for example, φ400 mm, and the roll width is from about 980 mm to 2300 mm of the width dimension of the continuously cast slab 4. is there.

  Since cracks that occur in continuous casting rolls due to thermal stress from the slab usually occur in the circumferential direction, conventionally, multiple cracks in the circumferential direction have been formed in the roll surface layer to mitigate crack stress. To be done.

  The present inventors first verified the effect of relaxing the conventional crack stress. FIG. 3 shows that in the continuous casting roll 5, as shown in the above-mentioned Patent Document 1, grooves having a fixed dimension for preventing cracks are formed at equal intervals over the entire length of the roll width, and after performing continuous casting, the groove width is measured. An outline of the results is shown. In the graph of FIG. 3, the horizontal axis is the position in the width direction of the roll, and the portion where the groove width is small is the outer peripheral surface 13 of the convex portion 12 sandwiched between the grooves 11 as shown in FIG. 2. Indicates that the slab has been crushed by the slab, that is, sag has occurred. It was found that this phenomenon hardly occurred at the center portion in the width direction of the roll and occurred at a position where both end portions in the width direction of the slab to be manufactured contacted. In addition, it has been found through experiments and the like that cracks are likely to occur at the center in the width direction of the roll and are less likely to occur at both ends.

Therefore, in the present invention, as shown in FIG. 4, grooves having different shapes are formed in the widthwise center portion 5 c and the left and right end portions 5 e of the continuous casting roll 5. That is, a deep groove 21 is formed in the central portion 5c in the width direction of the continuous casting roll 5 so that distortion due to thermal expansion is absorbed, and rigidity is increased in the end portions 5e on both ends of the central portion 5c. A shallow groove 22 is formed. Both the deep groove 21 and the shallow groove 22 are formed in the circumferential direction of the continuous casting roll 5. The range in which the deep groove 21 is formed is preferably a range of, for example, about 650 mm to 750 mm at the center of the continuous casting roll 5. Thus, even when the cast strip 4 to be produced of 980mm width is the minimum size, range surface of the continuous casting roll 5 widthwise ends of the slab 4 are in contact, the high shallow groove 22 rigid formed It becomes. Therefore, the local reduction | decrease of the roll diameter which the width direction both ends of the slab 4 contact can be prevented.

  FIG. 5 is an enlarged view of a cross section of a portion A in FIG. 4 and shows examples of the deep groove 21 and the shallow groove 22. The shape of the deep groove 21 formed in the roll center portion 5c may be a U shape as shown in FIG. 5 (a), or may be a shape in which the bottom of the slit swells round as shown in FIG. 5 (b). good.

  The groove bottom portion of the deep groove 21 has an R shape in order to prevent cracks due to stress concentration, and the Rc dimension is 2 mm to 4 mm. The groove depth Dc is required to be 15 mm or more so that the heat from the slab does not affect the groove bottom, but is 30 mm or less so that the entire roll will not be damaged if the groove bottom cracks. The groove width Wc is required to be 2 mm or more so that the side surfaces of the groove 21 do not come into contact with each other due to the thermal expansion when the slab contacts, but the width of the convex portion 12 sandwiched between the grooves 21 is ensured. In order to maintain the rigidity of the convex portion 12, the thickness is set to 6 mm or less. The groove pitch Pc is preferably as small as possible in order to relieve the thermal stress of the outer peripheral surface 13 of the convex portion 12, but at least 10 mm is necessary to ensure the rigidity of the convex portion 12, and is 10 mm to 30 mm. .

  The bottom of the shallow groove 22 formed at both ends 5e of the roll 5 has an R shape to prevent stress concentration, and the Re dimension is 30 mm to 40 mm. The groove depth De is preferably as small as possible in order to ensure the rigidity of the convex portion 12, but at the same time, a depth that prevents the high-temperature cast slab from coming into contact with the groove bottom is necessary, and is 2 mm to 8 mm. The groove width We is determined by the Re dimension and the groove depth De. The groove pitch Pe is preferably large in order to ensure the rigidity of the convex portion 12, but is 50 mm to 70 mm in order to absorb local thermal elongation at the same time.

  The reference values for determining the groove dimensions of the deep grooves 21 and the shallow grooves 22 were set based on simulation results such as FEM analysis.

  As described above, the continuous casting roll 5 of the present invention is provided with the deep groove 21 in the center portion 5c in the width direction and the shallow grooves 22 in the end portions 5e on both ends thereof, thereby preventing the center portion 5c from cracking. In addition, it is possible to prevent a reduction in the roll diameter at the portion where the end of the slab 4 contacts. Therefore, deterioration of the roll can be suppressed and the life can be extended, and the quality of the slab can be improved.

  The continuous casting roll 5 of the present invention is applicable, for example, when the temperature of the slab 4 is in the range of about 600 ° C. to 1000 ° C., and can be used in any temperature range in the continuous casting machine 1.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  The present invention can be applied to a slab conveying roll of a continuous casting facility.

DESCRIPTION OF SYMBOLS 1 Continuous casting machine 2 Tundish 3 Mold 4 Cast piece 5 Continuous casting roll 5c Center part 5e End part 11 Groove 12 Convex part 13 Outer peripheral surface 21 Deep groove 22 Shallow groove

Claims (2)

A continuous casting roll used for transporting continuously cast slabs,
A plurality of circumferential grooves are formed on the surface layer of the roll over the entire width direction,
The groove formed in the range of 650 mm to 750 mm in the center in the width direction of the roll has an R dimension of 2 to 4 mm, a groove depth of 15 to 30 mm, a groove width of 2 to 6 mm, and a groove pitch of 10 at the groove bottom. ~ 30mm deep groove,
The grooves formed at both ends in the width direction of the roll are shallow grooves having an R dimension of 30 to 40 mm, a groove depth of 2 to 8 mm, a groove width of 20 to 24 mm, and a groove pitch of 50 to 70 mm. A continuous casting roll characterized by that. A continuous casting method for conveying a slab using a continuous casting roll,
  The continuous casting roll has a plurality of circumferential grooves formed on the surface layer of the roll over the entire width direction,
  The groove formed in the center in the width direction of the roll is a deep groove having an R dimension of 2 to 4 mm, a groove depth of 15 to 30 mm, a groove width of 2 to 6 mm, and a groove pitch of 10 to 30 mm. ,
  The groove formed at both ends in the width direction of the roll including at least the portions in contact with both ends in the width direction of the slab of the smallest dimension has a R dimension of 30-40 mm at the bottom, a groove depth of 2-8 mm, and a groove width. Is a shallow groove having a groove pitch of 50 to 70 mm and a groove pitch of 50 to 70 mm.

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