JP4366157B2 - Strip caster - Google Patents

Description

  The present invention relates to a twin roll type strip caster.

  Strip casting is known as one of the methods for manufacturing a thin metal plate. A twin roll type strip caster (continuous casting apparatus) developed as such a strip casting has an axial center direction of a pair of left and right cooling rolls 1 arranged in parallel in the horizontal direction, as schematically shown in FIG. Side dams 2 are arranged on both end surfaces so as to be in contact with the cooling roll 1, and raw metal hot water 3 is poured into a wedge-shaped gap formed between the pair of cooling rolls 1. The solidified metal is rapidly solidified by being cooled on the surface of each cooling roll 1, and the solidified metal is pressure-bonded between the roll gaps of the pair of cooling rolls 1 to produce a strip (thin plate) 4. . In this method, since a thin metal plate can be produced directly from the raw metal hot water 3, the hot rolling process can be omitted and the thin plate production process can be greatly simplified. Therefore, energy saving and production cost reduction can be achieved. It is known as an effect that can be expected.

  By the way, the cooling roll 1 used in the above-described twin-roll type strip caster was initially designed so that the surface in contact with the hot water becomes a smooth surface with very small irregularities. When contacting the surface of the cooling roll 1, the entire surface of the cooling roll 1 is cooled at a time, so that the heat removal of the hot water 3 occurs abruptly and is formed between the cooling rolls 1. In the thin plate 4, there is a problem that the solidification strain of the surface portion becomes large.

  For this purpose, as a measure for reducing the sudden heat removal when solidifying the hot water 3 of the raw material alloy and suppressing the surface strain, the surface of the cooling roll 1 is provided with a large number of irregularities, When the hot water 3 is brought into contact with the cooling roll 1, the hot water 3 is brought into contact only with the convex portions on the surface of the cooling roll 1 and is not brought into contact with the concave portions due to surface tension. It has been proposed that the cooling roll 1 be carried out in a state of being dispersed from a large number of places in contact with the convex portions on the surface.

  As the surface structure of the cooling roll 1 based on this idea, for example, as shown in FIG. 3, a large number of convex portions 5 extending in the circumferential direction are formed on the outer circumferential surface of the cooling roll 1 at a required interval in the axial direction. Further, as shown in FIGS. 4 (a), (b), (c), (d), and (e), the outer peripheral surface of the cooling roll 1 is formed on the outer peripheral surface of the cooling roll 1 as shown in FIGS. , Rhombuses, rectangles, triangles, hexagons, and circular convex portions 7 divided by a large number of grooves 6, and a large number of grooves extending in a spiral direction at a required angle with respect to the axial direction as shown in FIG. 6 formed with a large number of convex portions 7 extending in the spiral direction (see, for example, Patent Document 2), the outer surface of the cooling roll 1 is formed with irregularities by sandblasting or the like, and the surface of the cooling roll 1 is formed. What was processed into the required rough surface (for example, Patent Document 3 Irradiation), and the like have been proposed.

  For the cooling roll used in the single roll type strip caster, a large number of convex portions extending in the circumferential direction are formed on the surface of the cooling roll at a required interval in the axial direction, and the cross-sectional shape of the convex portion is trapezoidal. Have also been proposed (see, for example, Patent Document 4).

Japanese Patent Laid-Open No. 3-128149 Japanese Patent Laid-Open No. 2-165849 Japanese Patent No. 2733776 US Pat. No. 4,865,117

  However, in the above-described twin-roll strip caster, during operation, each cooling roll 1 swings with a required amplitude in the gap direction at a period of about 50 Hz, and thus the roll gap is rapidly changed and opened and closed. Sometimes.

  In this case, as shown in Patent Document 1, when the convex portion 5 having a triangular cross-sectional shape is provided on the outer peripheral surface of the cooling roll 1, the thickness changes in the longitudinal direction of the manufactured strip. In other words, a so-called chatter is sometimes formed, and it is desired to prevent the occurrence of such a chatter.

  In order to form the convex portion 7 as shown in Patent Document 2 on the surface of the cooling roll 1, a large number of grooves 6 must be formed. There is a problem that increases.

  Furthermore, in what was shown in the said patent document 3, in order to obtain the cooling roll which provided the rough surface of the desired surface roughness equally on an outer peripheral surface, the implementation conditions of sandblasting must be set in detail. In addition, it takes time and time to prepare the sandblast, and there is a problem that time and time required for manufacturing the cooling roll increase.

  The cooling roll disclosed in Patent Document 4 is a cooling roll of a single roll type strip caster, and when the roll gap between the two cooling rolls is suddenly opened and closed by a twin roll type strip caster. It is not considered at all that chatter occurs. Therefore, what was described in the said patent document 4 cannot solve the problem that a chatter generate | occur | produces, when the roll gap of each cooling roll of a twin roll type strip caster is opened and closed rapidly.

  Therefore, as a result of repeated efforts and research to prevent chatter during continuous casting of a thin plate, the present inventors have made a cross section on the outer peripheral surface of the cooling roll 1 as shown in Patent Document 1 above. It has become clear that the generation of chatter in the case where the convex portion 5 having a triangular shape is provided is due to the following mechanism. That is, when the convex portion 5 having a triangular cross-sectional shape is provided on the surface of the cooling roll 1, the raw metal hot water 3 is usually very narrow at the top of the convex portion 5 as shown in FIG. It touches only the area. However, when the roll gap of the pair of cooling rolls 1 is suddenly opened and closed, the raw metal hot water 3 is formed in the concave portions between the convex portions 5 when receiving the shocking momentum of the cooling roll 1. To the depth level as indicated by the symbol e. In this case, the contact area between the hot water 3 and the convex portion 5 is changed from a very narrow region corresponding to the top of the convex portion 5 in a normal operation state to a depth level e on both side slopes of the convex portion 5. It is expanded to the width w of the corresponding area. For this reason, the ratio of the initial solidification width of the hot water 3 is greatly changed between the normal operation state and when the roll gap is opened and closed. In this way, as the roll gap of the cooling roll 1 is suddenly opened and closed, the initial solidification width of the hot water 3 is periodically changed. It has been clarified that chatters are produced by aligning in the longitudinal direction.

  Therefore, even if the roll gap is suddenly opened and closed, if the initial solidification width of the raw metal hot water 3 is not changed so much, the change in the initial solidification thickness can be suppressed and the occurrence of chatter can be prevented. And made the present invention.

  Therefore, the object of the present invention is to suppress the change in the initial solidification width of the hot water even when the roll gap of the cooling roll is suddenly opened and closed, to prevent the occurrence of chatter, and more easily to manufacture. It is intended to provide strip casters.

In order to solve the above problems, the present invention is a twin-roll strip caster having a pair of left and right cooling rolls arranged in parallel in the horizontal direction, and the cooling roll has a cross-sectional shape on the outer peripheral surface of the roll. Protrusions having a substantially trapezoidal shape are provided in a series of spirals at a pitch of 0.3 to 0.1 mm, and the protrusions have a width that is 0.2 to 0.7 times the pitch of the protrusions on the top. cooling roll was 70~5μm inclination angle Rutotomoni provided with 40 degrees or less of the inclined surface, the height of the convex portion from a vertical plane perpendicular to the roll axis on both sides of and the flat surface has a flat surface And

According to the strip caster of the present invention, the following excellent effects are exhibited.
(1) Convex portions having a substantially trapezoidal cross-sectional shape are provided on the outer peripheral surface of the roll in a series of spirals at a required pitch, and the convex portions have a flat surface with a required width at the top and the flat surface. Since it has a configuration comprising inclined surfaces of 40 degrees or less on both sides, it can have a stable initial solidification width corresponding to the top flat surface of the convex portion during normal operation, and the roll gap of the cooling roll Even if the metal hot water that has been suddenly opened and closed and received impact force from the cooling roll enters the recesses between the projections, the angle from the vertical direction (vertical plane perpendicular to the roll axis) is By enlarging the contact area with the inclined surface set at a steep angle of 40 degrees or less, it is possible to suppress a large change in the initial solidification width of the hot water, thereby suppressing a change in the initial solidification thickness of the hot water. That the thickness of the manufactured thin plate changes. It is possible to prevent chatter from occurring.
(2) Since the convex portions are arranged in series in the spiral direction, the convex portions can be formed by engraving concave portions existing between the convex portions on the outer peripheral surface of the roll in the spiral direction. Therefore, since the outer peripheral surface of the cooling roll can be easily processed by an NC lathe or the like, labor and time required for the processing can be reduced, and the manufacturing of the cooling roll can be facilitated.
(3) By setting the width of the top flat surface of the convex portion to 0.2 to 0.7 times the pitch of the convex portion, in the normal operation and when the roll gap suddenly opens and closes The change in the initial solidification width can be efficiently suppressed, and the occurrence of solidification strain in the formed thin plate can be suppressed.
(4) The pitch of the convex portions is set to 0.3 to 0.1 mm, and the height of the convex portions is set to 70 to 5 μm. It is possible to efficiently disperse the places where the initial solidification of the hot water occurs, and it is possible to efficiently produce a thin plate with reduced solidification strain.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIGS. 1 (a) and 1 (b) show an embodiment of a strip caster of the present invention. A cooling roll 1 used in a twin roll strip caster having the same configuration as shown in FIG. Convex portions 8 having a substantially trapezoidal cross-sectional shape are provided in a series of spirals at a required pitch p, and the cross-sectional shape of the convex portions has a flat surface 9 having a required width a at the top and the flat surface. The cooling roll 1a of the present invention is assumed to be provided with the inclined surfaces 10 having an inclination angle θ of 40 degrees or less from the vertical direction (vertical plane orthogonal to the roll axis) on both sides of the sheet 9.

  The width a of the top flat surface 9 of the protrusion 8 is 0.2 to 0.7 times the pitch p of the protrusion 8. As described above, the width a of the top flat surface 9 is set to 0.2 to 0.7 times the pitch p. When the width a of the top flat surface 9 is smaller than 0.2 times the pitch p, the width a is usually Since the width (area) of the top flat surface 9 that comes into contact with the raw metal hot water 3 in the operation state is reduced, the hot water 3 that has received the shocking momentum of the cooling roll 1 a is interposed between the convex portions 8. When entering the position of the depth level e and coming into contact with the portions corresponding to the depth level e on the inclined surfaces 10 on both sides of the convex portion 8, the area change from the normal operation state becomes large. It is because it ends up. On the other hand, when the width a of the top flat surface 9 is larger than 0.7 times the pitch p, the effect of providing unevenness on the surface of the cooling roll 1a to disperse the solidification start point is reduced in order to suppress the solidification strain. Because.

  Furthermore, the pitch p of the protrusions 8 can be efficiently produced by efficiently distributing the portions where the initial solidification of the raw metal hot water occurs due to the unevenness provided on the surface of the cooling roll 1a, and suppressing the solidification distortion. Is 0.3 to 0.1 mm, preferably about 0.2 mm, and the height h of the convex portion 8 is 70 to 5 μm, preferably about 50 μm.

  When manufacturing the cooling roll 1a for split casters of the present invention, a cooling roll having a smooth outer peripheral surface in the axial direction is applied to, for example, an NC lathe and corresponds to the concave portions 11 between the convex portions 8. A groove having a shape may be engraved in the spiral direction so as to be threaded on the outer peripheral surface of the roll.

  In the state where the cooling roll 1a for split casters of the present invention is used as a cooling roll for a twin roll split caster as shown in FIG. The hot water 3 starts to solidify in a state where it contacts the top flat surface 9 of the convex portion 8 on the outer peripheral surface of each cooling roll 1a and does not contact the concave portion 11 between the convex portions 8 due to surface tension. For this reason, initial solidification is started with an initial solidification width corresponding to the width a of the top flat surface 9 of each convex portion 8, and at this time, the solidification start point is the position of the top flat surface 9 of each convex portion 8. Therefore, the hot water 3 is solidified in a state in which the solidification strain is suppressed, and then is formed on the surface of each cooling roll 1 by passing between the cooling rolls 1a. The solidified product is pressed and the thin sheet metal 4 is continuously formed.

  In the above, when each cooling roll 1a is vibrated in the gap direction for some reason and the roll gap is suddenly opened and closed, the raw metal hot water 3 that has received the shocking momentum of each cooling roll 1a is It is made to approach to the recessed level 11 between the convex parts 8 in the surface of each said cooling roll 1 to the depth level e. At this time, the hot water 3 is brought into contact with the depth level e on the inclined surface 10 of each convex portion 8 so that the initial solidification width of the hot water 3 corresponds to the depth level e. The initial solidification width of the hot water 3 is set as a stable width as the width of the top flat surface 9 of the convex portion 8 during normal operation, and both sides of the convex portion 8 are expanded. The inclination angle θ of the inclined surface 10 is set to be 40 degrees or less from the vertical direction (vertical surface perpendicular to the roll axis), so that the initial solidification expanded as the hot water 3 enters the concave portion 11. The initial solidification width during the normal operation of the width f, that is, the enlargement ratio (f / a) with respect to the width a of the top flat surface 9 of the convex portion 8 can be reduced.

  Therefore, even when the cooling roll 1a vibrates in the gap direction and the roll gap is suddenly opened and closed, the change in the initial solidification width can be suppressed to a small value, so that the change in the initial solidification thickness of the hot water can be suppressed. In addition, since the change in the thickness of the manufactured thin plate 4 can be prevented in advance, the occurrence of chatter can be prevented in advance.

  Furthermore, since the convex part 8 of the cooling roll 1a can be formed by engraving a series of concave parts 11 in a spiral direction on the outer peripheral surface of the roll, it can be easily processed by an NC lathe or the like. Compared to what is described in Patent Document 3, the labor and time required for processing the surface of the cooling roll 1a can be greatly reduced, and manufacturing can be facilitated.

  In addition, this invention is not limited only to the said embodiment, In addition to the side dam 2, as a twin roll type split caster, the lower end is the outer periphery of each cooling roll 1a above each cooling roll 1a. A barrel weir is provided in contact with the surface over the entire length in the axial direction so that hot water can be stored at a required height level above the roll gap of the cooling roll 1a by the barrel weir and the side weir 2. You may apply also to the cooling roll 1a of the twin roll type split caster of the type formed by forming the hot water sump part. Although the surfaces on both sides of the convex portion 8 are shown as having a substantially trapezoidal shape with the inclined surface 10 having an inclination angle θ from the vertical direction (vertical surface orthogonal to the roll axis) of less than 40 degrees, the inclination angle The angle θ may be 0 degree, that is, both side surfaces of the convex portion 8 may be surfaces perpendicular to the roll surface, and various changes can be made without departing from the scope of the present invention. It is.

BRIEF DESCRIPTION OF THE DRAWINGS One Embodiment of the cooling roll for split casters of this invention is shown, (A) is a schematic side view, (B) is sectional drawing which expands and shows a surface part. It is a cutting side view showing an outline of an example of a twin roll type split caster. It is a general | schematic cut side view which shows the surface part of the cooling roll for twin roll type split casters proposed conventionally. (A), (b), (c), (d), (e), and (f) are all schematic views showing surface portions in other types of cooling rolls for twin roll split casters that have been conventionally proposed.

1a Cooling roll 8 Convex part 9 Top flat surface 10 Inclined surface (surface)
a Width of the top flat surface p Pitch pitch θ Inclination angle

Claims (1)

A twin-roll strip caster having a pair of left and right cooling rolls arranged in parallel in the horizontal direction, and the cooling roll has a spiral-shaped convex portion on the outer peripheral surface of the roll. Provided in series at a pitch of 0.3 to 0.1 mm, the convex part has a flat surface with a width 0.2 to 0.7 times the pitch of the convex part at the top, and both sides of the flat surface strip caster, wherein the inclination angle from a vertical plane perpendicular to the roll axis is cooled rolls Rutotomoni, the height of the convex portion and 70~5μm provided with 40 degrees or less inclined surface.

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