JPH07115133B2 - Thin plate continuous casting apparatus and operating method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a twin roll type continuous casting machine for continuously casting a thin plate directly from a molten metal (for example, molten steel).

[Background of the Invention and Prior Art]

A pair of internal cooling rolls, whose axes rotating in opposite directions are horizontal, are arranged in parallel and opposite to each other with an appropriate gap, and the roll circumferential surface (upper half of the cylindrical surface in the direction along the roll axis is located above the gap). A so-called twin roll continuous casting machine is known in which a pool is formed on a surface and the molten metal in the pool is continuously cast on a thin plate through the gap while being cooled by a rotating roll circumferential surface. It has been proposed to apply such a twin roll type continuous casting machine to continuous casting of steel to directly produce a thin steel sheet from molten steel.

For continuous continuous casting of thin plate castings from the gap between the roll pairs, a pool of molten metal is formed on the circumferential surface above the gap between the roll pairs to maintain the molten metal level substantially constant. Thus, it is necessary to continuously inject the molten metal into this pool. In order to form this basin, a pair of dams having a surface perpendicular to the roll axis is required on the circumferential surface of the roll to regulate the flow of the hot water in the direction along the roll axis.
This dam also usually serves to control the width of the sheet slab. This dam is referred to herein as a "side dam". In addition to the side dams arranged on the left and right sides, a pair of front and rear weirs (also called long-side dams) having faces along the roll axis are erected on the circumferential surface of the roll pair so as to be orthogonal to the side dams. A side dam and the front and rear weirs may form a box-shaped basin, but if the radius of the roll pair is sufficiently large, the front and rear weirs in the direction along the roll axis are not always necessary. The circumferential surface itself can play the role of this front and rear weir.

This pair of side dams is a movable side dam that presses an endless metal belt or an endless track zone (endless belt) against the side surface of the roll pair to move at a speed commensurate with the casting speed of the slab, and a fire-resistant side dam. A fixed type side dam in which a plate-shaped object is fixed to the left and right side portions of a roll pair is known. Generally, the latter fixed side dam has an advantage that the device configuration and operation control are not complicated unlike the former.

For fixed side dams, it is known that the distance between the two side dams is smaller than the roll width (the length from one end of the roll to the other end), and is equal to the roll width. . In the former case, both side dams are raised on the roll circumference so that the bottoms of both side dams are in sliding contact with the roll circumference. In the latter case, the inner surface of each of the side dams is in sliding contact with the roll side surfaces in the direction perpendicular to the roll axis (the roll side surfaces are referred to as roll side surfaces in this specification), that is, in the roll pair. Side dams are fixed so that both ends are sandwiched by both side dams.

Normally, the material of the fixed side dam is a refractory material with good heat insulation. This is because the molten metal that contacts the side dam must be prevented from solidifying on the surface of the side dam. Such a heat-resistant refractory is generally inferior in wear resistance to solidified metal and is more likely to be scratched and scratched. Therefore, a situation occurs in which the refractory is damaged, and when it becomes severe, a breakout occurs. Further, in the above-mentioned method in which the side dams are fixed so as to sandwich the roll side surfaces of both rolls, a gap is created in the sliding portion between the roll side surface and the inner surface of the side dam due to the pressing of the plate end when passing through the roll gap. ， There is hot water. When these troubles occur, casting cannot be continued stably. Therefore, the conventional general idea was to use a refractory material with good wear resistance and as high strength as possible for this side dam.

Whichever side dam method is adopted, a part of the molten metal in the pool forms a thin solidified shell on each surface of each rotating roll, and these grow as the roll rotates and pass through the gap between the twin rolls. Will be done. At that time, the solidified shell is rolled (rolled) in the vicinity of the roll gap (the narrowest gap portion) where the roll gaps are closest to each other, and is formed into a thin plate having a predetermined thickness. Therefore, by crushing (rolling) the solidified shell, the solidified shell tends to spread in the width direction in the vicinity of the roll gap. As a result, the end of the cast plate exerts a large pressure on the side dam. In the case of a movable side dam, since the side dam is moved according to the moving speed of the cast plate, the problem of friction between the side dam and the end of the cast plate practically does not occur. It is inevitable that a large amount of friction is generated between the section and the fixed side dam. As a result, damage to the side dam refractory, cracking of the edge due to unreasonable stress applied to the edge of the plate, occurrence of defective shape, and even occurrence of soldering in the sliding contact area will occur and stable operation will be performed. It becomes a big obstacle in the above. This problem is an important problem to be solved especially in casting for steel, which is not found in soft non-ferrous metal having a low melting point in view of high melting point and high strength of cast plate material.

The inventors proposed in Japanese Patent Application No. 62-84555 an invention of a thin plate continuous casting machine that can be called a "grinding dam method" (or an intermediate method between a movable type and a fixed type) that fundamentally solves such a problem. did. This is contrary to the conventional idea of using a high-strength refractory material with good wear resistance for the side dam. Contrary to this, a refractory material with good machinability was used to cast a side dam with good machinability. By positively feeding the side dam in the casting direction, the side dam is forcibly abraded at the friction portion between the side dam and the roll surface and the plate end to be cast. After that, the present inventors repeated the casting test by this grinding dam method, but in order to continuously continue the grinding wear of the side dam and perform stable casting, a new device from another angle is required. I found out.

[Object of the Invention]

The present invention is directed to solving the above-mentioned problems by using Japanese Patent Application No. 62-8455.
It is intended to further improve the grinding dam method proposed in No. 5.

[Structure of Invention]

The present invention, which has been made to achieve the above-mentioned object, has a pair of side dams for arranging a pair of internal cooling rolls rotating in opposite directions in parallel and facing each other, and forming a pool on the circumferential surface of the roll pair. In a thin plate continuous casting device in which the side dams are continuously cast into thin plates through the gap between the roll pairs by arranging the side dams at intervals on the both sides of the rolls at intervals substantially corresponding to the casting plate width. It is made of a material with good machinability and is equipped with a first feeding mechanism that moves this side dam in the casting direction and a second feeding mechanism that moves this side dam in the direction along the roll axis. The roll circumferential surface and the roll side surface to be in contact with each other are formed into rough surfaces having grinding ability, and a part of the thickness of the side dam is overhung on the roll circumferential surface in the cast state. And wherein the door.

That is, the present invention is intended to grind the side dam in the roll axis direction in addition to the grinding of the side dam in the casting direction in the grinding dam method proposed in the above-mentioned Japanese Patent Application No. 62-84555. By performing proper grinding in the direction of the roll and in the direction of the roll axis, more stable operation becomes possible, and good casting can be performed even with thick plates.

One of the characteristic operating methods of this apparatus is to rotate the roll with the gap between the roll pair being smaller than the target plate thickness at the beginning of casting or before, and move the side dam by the second feeding mechanism to move the roll. A method is provided in which the inner surface of the side dam is ground by the side surface, then pouring is started, the gap between the roll pairs is expanded to the target plate thickness, and then the side dam is moved in the casting direction by the first feeding mechanism. It At that time, the device configuration is such that the gap between the roll pairs can be adjusted.

〔Example〕

The contents of the present invention will be specifically described below with reference to the embodiments of the drawings.

FIG. 1 shows a state during casting in a steady operating state of the apparatus of the embodiment of the present invention. In the figure, reference numerals 1a and 1b are a pair of internal cooling rolls arranged so as to face each other so that they rotate in opposite directions (the rotation directions of both are indicated by arrows) with their axes horizontal. In the illustrated example, both of the rolls 1a and 1b are water-cooled rolls. More specifically, each of the roll pairs 1a, 1b has a coil-shaped cooling water passage formed inside the drum forming the circumferential surface R (not shown in the drawing). By passing water through the cooling water passage, the circumferential surface R is cooled to a predetermined temperature. The cooling water is supplied to and discharged from the cooling water passage inside the circumferential surface R from the roll shaft.

2 is the molten metal in the pool formed on the circumferential surface R of the rolls 1a and 1b, 3a and 3b are side dams made of machinable refractories, 4
Is a cast plate to be cast, and 5a and 5b are backup plates that support the side dam from the outside.

The side dams 3a, 3b made of machinable refractory have a sufficient area to form a pool on the circumferential surface of the roll during operation, and the area near the roll gap (the narrowest gap between the rolls) is sufficient from the outside. It has an area that can be surrounded by the backup plate 5a, 5b from the outside, and the entire backup plate 5a
A feeding mechanism for forcibly moving in the casting direction and the roll axis direction is provided in a and 5b. In the example shown in the figure, the first feeding mechanism for feeding in the casting direction is a plurality of vertically installed screw columns 8 (however, a single structure is also possible),
The nuts 9 fixed to the backup plates 5a, 5b are screwed together, and the columns 8 are rotated about their axes so that the backup plates 5a, 5b are moved in the casting direction. The side dams 3a and 3b are sent out in the casting direction by the first sending mechanism. On the other hand, the second feeding mechanism for feeding in the roll axis direction connects the feeding rods 6a, 6b having axes parallel to the roll axis to the outer surfaces of the backup plates 5a, 5b, and these feeding rods 6a, 6b It is designed to move in the pressing direction. It is preferable that the rods 6a and 6b are sent out by using a hydraulic cylinder. An air cylinder can be used in place of the hydraulic cylinder, and a rack and pinion system may be used. The first feeding mechanism and the second feeding mechanism are configured so that they can be driven independently of each other so that only one of them can be moved or at the same time.

In the state during casting as shown in FIG. 1, the side dams 3a, 3b are continuously moved in the casting direction by the first feeding mechanism. On the other hand, in the second casting mechanism, the extrusion is stopped in a steady casting state and locked in that position.
Extrusion in the axial direction of the roll by the second feeding mechanism is the place where the grinding wear due to the edge of the cast plate is particularly advanced in the vicinity of the roll gearup on the inner surface of the side dams 3a, 3b during casting. This is done as a safety measure to prevent molten metal leakage from the pipe, and when the roll gap gap increases or decreases when the strip width is changed, the amount by which the end of the cast plate expands outward near the roll gap changes. Grinding to eliminate the gap between the inner wall of the side dam and the roll, and to secure the amount of overhang required for casting with a small roll gap at or before the start of casting. In particular, it has its main meaning.

In order to favorably grind the side dams 3a, 3b by such a first feeding mechanism and a second feeding mechanism, the roll portion in contact with the side dams 3a, 3b is formed on a rough surface having a grinding ability. In Fig. 1, the rough surface on which the side dams 3a, 3b are ground by the roll by the first feeding mechanism is the circumferential surface of the roll side end indicated by 10, and the side dams 3a, 3b are rolled by the second feeding mechanism. The rough surface ground by is the roll side surface indicated by S. The roughness and hardness of these rough surfaces 10 and S are selected according to the material of the side dam and the moving speed of the side dam, but a coating with irregularities such as ceramics, cermet, and hard alloy is formed by thermal spraying. Is good. Alternatively, a film of an inorganic compound or alloy may be formed by plating or other film forming technique, and the film may have an appropriate surface roughness. Alternatively, only the portion having the rough surface 10 and S may be configured as a disk-shaped member different from the roll body, and this may be detachably attached to the roll body. In this case, it is convenient because replacement and repair can be easily performed when the grinding ability decreases. In order to prevent clogging of the rough surface 10 or S during grinding of the side dams 3a, 3b during casting, a brush or a vacuum cleaner may be installed in sliding contact with the rough surface. Is also advantageous. First
In the figure, an example is shown in which a brush 11 for preventing clogging of the rough surface 10 is attached.

FIG. 2 shows that the backup plate is pressed by using a plurality of delivery rods 6a, 6a ', 6b, 6b', and a large number of radial grooves are formed on the roll side surface S to form a rough surface. , An apparatus similar to that of FIG. In this case, the side dams 3a and 3b can be more stably attached to the roll side surface S.
It can be pressed against and the grinding ability by the S surface is further improved.

FIG. 3 schematically shows the state of the inner surface of the side dam during casting. Although one side dam 3b is shown in the figure, the other side dam 3a also appears in a similar state. In Fig. 3, reference numerals 12 and 12 'indicate the bottom surface of the side dam ground by the rough surface 10 of the roll circumferential surface,
The lower edge 13 comes into contact with the end of the cast plate to be cast and is ground. Reference numeral 14 indicates a surface ground by the roll side surface S. Curved lines a and a'shown by broken lines are the lines showing the boundary level with the molten metal of the thin shell solidified from the molten metal on the circumferential surface of the roll. This level of solidification shell is point A
At the point indicated by, the merged solidified shells are rolled between the roll gaps. By this rolling, the plate edge is expanded outward in the plate width direction, and the lower edge 13 of the side dam is ground by the expanded plate edge. The degree of grinding of the lower edge 13 changes depending on the thickness of the plate to be cast, the casting speed, and other casting conditions, but in some cases, the width of the bottom parts 12, 12 ', that is, the thickness of the side dam existing on the circumferential surface of the roll ( The width indicated by W ₁ in FIG. 3 (called an overhang amount) may be exceeded. Even in this case, in the side dam of the present invention, the surface 14 having a sufficient size and thickness for sliding contact with the roll side surface S exists on the outer side around the side dam bottom portions 12, 12 'and the lower edge 13. The outer surface 14 deviating from the circumferential surface of the roll can be called a backup surface, and its thickness can be called a backup amount.) This surface 14 presses the plate edge. At that time, backup surface 14
Also, the part 15 to be ground by the plate edge is formed, but if a sufficient backup amount is secured, the risk of molten metal leakage can be avoided.

4 and 5 schematically show an example of a characteristic operating method of the apparatus of the present invention. FIG. 4 shows a state before starting pouring, and FIG. 5 shows a casting state. It is shown in a plan view. In the device of the present invention, as the new side dams 3a and 3b, in addition to an area having a flat inner surface and having an inner surface sufficient for damming the hot water in the basin, a large area covering the roll side surface near the roll gearup is provided. Use what you have,
Before the start of pouring, this is pressed against the roll side surface S as shown in FIG. Then, the rolls 1a and 1b are rotated and forcedly moved in the roll axial direction by the delivery rods 6a and 6b of the second delivery mechanism. In this case, the roll gap is made smaller than the target plate thickness of the cast plate to be cast, and in some cases the roll gap is not present. Due to this forced feed, the inner surfaces of the side dams 3a, 3b are worn away by the roll side surface S, reducing the distance between them, but when the grinding progresses to near the target plate thickness, the feed is prevented.

Next, the pouring is started while rotating the roll. After starting the pouring, the roll gap is gradually expanded to the target plate thickness. At the same time, the side dams 3a and 3b are forcibly moved in the casting direction by the first feeding mechanism at the same time, and the side dam bottom part (12, 12 'curved surface part in Fig. 3) and the roll circumferential surface due to the spread of the roll gap. Make sure there is no gap between With this, the steady state of casting is entered, and thereafter, while moving the side dams 3a, 3b at the predetermined speed in the casting direction by the first feeding mechanism,
Continue pouring into the pool.

In this way, by appropriately driving the second feeding mechanism and the first feeding mechanism, a cast plate having a relatively thick plate can be smoothly operated from the start of casting.
In this case, it goes without saying that it is necessary to use a twin roll type continuous casting machine capable of adjusting the roll gap.
As such a twin roll type continuous casting machine, one having the device structure proposed in Japanese Patent Application No. 63-42806, which is assigned to the same applicant, can be preferably applied.

As the material of the side dams 3a, 3b used in the device of the present invention, a refractory material is suitable because it must have good heat insulation, but in the case of the present invention, it must also have good machinability. . Suitable materials for this include heat-insulating bricks with good machinability, ceramic fiber boards, and boron nitride (BN). Backup plate 5
High-strength materials such as alumina graphite, magnesia graphite, precipitation hardening copper-based alloy, and steel alloy can be used as a and 5b. On the other hand, it is desirable that the grinding ability of the rough surface of the roll that grinds the side dams 3a, 3b is maintained constantly and does not change over time. Therefore, it is preferable that only the rough surface portion is formed of a hard material layer, and the surface of this material material layer is formed into a rough surface having grinding ability. The hard material layer is formed by plating hard metal such as Ni and Ni-based alloys, Ni-Fe alloys, Cr and Cr-based alloys, and Fe alloys on the surface of the base material on the circumferential surface of the roll, or hard metal or ceramics. Alternatively, it may be composed of a sprayed layer of cermet. Ni-Cr alloy, carbon steel, stainless steel, etc. are used as the sprayed metal, and Cr ₂ O ₃ , TiO are used as the sprayed ceramics.
₂ , Al ₂ O ₃ , ZrO _2, etc., and Zr as a thermal spray cermet
_{O 2 -NiCr, Cr 3 C 2} -NiCr, WC-Co or the like can be used. When a hard material surface is formed by thermal spraying, if the thermal sprayed layer is formed under the condition that natural unevenness is formed on the surface by the deposition of thermal spray particles, the thermal sprayed layer remains as it is and the above-mentioned abrasion of the machinable side dam is consumed. It is possible to make it a rough surface that can be satisfactorily performed. In order to improve the adhesion of the thermal sprayed layer to the roll base material, it is preferable to form the thermal sprayed layer after subjecting the roll base material to an undercoating treatment depending on the type of the roll base material. Metal plating can also be adopted for this base treatment. Alternatively, the surface that has been roughened in advance by blasting or the like may be subjected to thermal spraying. When the hard material surface is formed only by metal plating, or when the surface is made smooth by thermal spraying, roughening treatment is preferably performed. For this roughening treatment, emery polishing, blasting treatment or the like may be applied depending on the type of the hard material. This roughening treatment is usually performed before the start of casting, but it is more convenient if it can be performed even during the rotation of the roll during casting. Further, if a large number of radial grooves are formed on the roll side surface as in the example of FIG. 2, the grinding ability can be further improved.

〔The invention's effect〕

As described above, according to the present invention, the thin plate continuous casting apparatus proposed by Japanese Patent Application No. 62-84555 is further provided with the second feeding mechanism for pressing the side dam in the roll axial direction. While maintaining the characteristics of the -84555 grinding dam method and smoothly performing the casting start operation, even if the edge of the cast plate during casting causes excessive damage to the overhang portion of the side dam, this second feeding Since it can be restored immediately by operating the mechanism, stable operation is possible, which can greatly contribute to continuous casting of good quality cast sheets, especially steel sheets.

[Brief description of drawings]

FIG. 1 is a perspective view during casting showing an essential part of an embodiment of the apparatus according to the present invention, FIG. 2 is a perspective view showing an essential part of another embodiment of the apparatus according to the present invention, and FIG. 4 is a perspective view of the side dam of the device according to FIG.
FIG. 5 is a plan view of the device of the present invention for explaining the state before the start of pouring, and FIG. 5 is a plan view of the device of the present invention for explaining the casting state. 1a, 1b …… pair of internal cooling rolls, 2 …… bath, 3a, 3b ……
Side dams, 4 ... Cast plates to be cast, 6a, 6b ... Sending rod of the second sending mechanism, 8 ... Struts with threads of the first sending mechanism, 10 ... Rough surface of roll circumferential surface, 12 , 12 ′
...... Side dam bottom surface that makes sliding contact with the rough surface of the roll circumference, 1
3 …… The lower edge of the side dam near the roll gap, 14 …… The inner surface of the side dam that is in sliding contact with the side surface of the roll.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Matsunaga 4976 Tomita, Shinnanyo-shi, Yamaguchi Prefecture, Shunan Research Institute, Nisshin Steel Co., Ltd. (56) Reference JP-A-63-26243 (JP, A)

Claims (3)

[Claims] 1. A pair of internal cooling rolls that rotate in opposite directions are arranged in parallel and face each other, and a pair of side dams for forming a pool of molten metal on the circumferential surface of the roll pair substantially correspond to the width of the casting plate. In a thin plate continuous casting device, which is arranged on both sides of the roll with a gap and continuously casts the hot water of the pool into a thin plate through the gap of the roll pair, the side dam is made of a material having good heat insulation and machinability. A roll-circumferential surface on which the first dam mechanism for moving the side dam in the casting direction and the second heat-discharging mechanism for moving the side dam in the direction along the roll axis are provided, and the side dam comes into sliding contact with the roll. And the roll side surface is formed as a rough surface having grinding ability, and a part of the thickness of the side dam overhangs on the circumferential surface of the roll in the cast state. 2. The thin plate continuous casting apparatus according to claim 1, wherein the pair of internal cooling rolls are such that the gap between the pair of rolls is adjustable. 3. A pair of internal cooling rolls rotating in opposite directions are arranged in parallel to each other, and a pair of side dams for forming a basin on the circumferential surface of the rolls substantially correspond to the width of the casting plate. A device for continuously casting the hot water of the hot water pool, which is arranged on both sides of the roll, with a gap between the roll pair into a thin plate, wherein the side dam is made of a material having good heat insulation and machinability. In addition, a first feeding mechanism for moving the side dam in the casting direction and a second feeding mechanism for moving the side dam in the direction along the roll axis are provided, and the side circumferential surface of the roll that comes into sliding contact with the roll and When continuously casting thin sheets with a machine with a rough side surface for grinding the roll side surface, with the gap between the roll pairs smaller than the target sheet thickness at the beginning or before casting. The Lumpur by moving the rotating and the side dams in the second delivery mechanism to start pouring in helping to grind the inner surface of the side dam in the roll side surface, then,
A method for operating the apparatus, wherein the side dam is moved in the casting direction by the first feeding mechanism after expanding the gap between the roll pairs to the target plate thickness.