JPH09206893A - Side weir lubrication structure of thin sheet continuous casting machine and thin sheet continuous casting method - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To suppress an increase in casting cost by making it possible to use a relatively inexpensive solid lubricant such as molybdenum disulfide and graphite, which has not been conventionally applicable because it is remarkably oxidized at high temperature While achieving long-term casting. SOLUTION: When a molten metal is poured into a molten metal pool part defined by a pair of cooling drums and side dams, and then the molten metal is continuously cooled and solidified on the rotating peripheral surface of the cooling drum while continuously casting a thin plate. In order to continuously supply the solid lubricant while pressing it against the sliding surface of the cooling drum side weir, the guide pipe that guides the solid lubricant to the sliding surface is provided with water cooling means, and gas is introduced into the guide pipe. Meanwhile, the solid lubricant is continuously supplied under a reducing or inert gas atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to lubricate a space between an end surface of a cooling drum and a side dam when continuously casting a thin plate using a thin plate continuous casting machine provided with a pair of cooling drums. And a method for continuously casting thin plates performed on the premise of the side dam lubrication structure.

[0002]

2. Description of the Related Art Recently, attention has been focused on a method for directly producing a thin plate having a thickness of about several mm close to a final shape from a molten metal such as molten steel. According to this continuous casting method, it is not necessary to carry out a multi-step hot rolling process as in the prior art, and rolling to a final shape may be light, so that the process and equipment can be simplified.

As one of such continuous casting methods, there is a twin drum method (Japanese Patent Laid-Open No. 60-137562).
FIG. 3 is a perspective view for explaining the outline of the twin drum method. In this system, as shown in this figure, a pair of cooling drums 1a and 1b that rotate in opposite directions are horizontally arranged, and the cooling drums 1a and 1b and the side dams 2a and 2b are arranged.
The basin 3 is formed in the recess defined by b. Molten metal is poured into the pool 3 from a container such as a tundish via a pouring nozzle. The molten metal 4 contained in the molten metal pool 3 is cooled at the portions in contact with the cooling drums 1a and 1b and solidifies to form a solidified shell.

This solidified shell is composed of cooling drums 1a and 1b.
Along with the rotation of the cooling drums 1, the pair of cooling drums 1a and 1b move to the position closest to each other, that is, the so-called drum gap portion 6 while increasing its thickness,
The solidified shells formed on the surfaces a and 1b are pressed together here to form the desired metal ribbon 5. In addition, 18 is an end surface of the cooling drum, and 19 is a sliding surface.

As seen in Japanese Utility Model Laid-Open No. 63-90548 and its specification, in such a thin plate continuous casting machine, the side dams 2a and 2b are generally heat insulating materials housed in a side dam case, The base member is planted in the material, and the ceramic member is planted on the surface of the base member corresponding to the cooling drum. During casting, the side dam is pressed against the end surface of the cooling drum, and the ceramic member is abraded by the sliding surface of the cooling drum to eliminate the gap between the end surface of the cooling drum and the side dam to prevent leakage of molten steel. Further, as disclosed in Japanese Patent Laid-Open No. 61-266160, the side dam is generally vibrated, which promotes wear of the ceramic member.

Therefore, the continuous casting amount of the thin plate by the thin plate continuous casting machine is determined by the wear rate of the side dam ceramic member due to the sliding on the end surface of the cooling drum. Therefore, it is extremely important to suppress the wear of the ceramic member in order to increase the casting amount.

Since such wear of the ceramic member is affected by factors such as hardness, surface temperature, and roughness, in order to suppress wear of the ceramic member, it contacts the sliding surface of the cooling drum. It is effective to supply a lubricant to the wear surface of the ceramic member. As a result, the surface temperature of the ceramic member is lowered, and it is possible to prevent the end surface of the cooling drum from being roughened, and it is possible to reduce the friction coefficient between the sliding surface of the cooling drum and the worn surface of the ceramic member.
As a result, the side weir is prevented from opening and the molten steel sealing property is improved.

Here, as means for supplying the lubricant to the wear surface of the ceramic member, Japanese Patent Laid-Open No. 4-81250 discloses that a solid lubricant is passed through the through hole from the back side of the side dam having the through hole. A method of pressing the end face has been proposed.

[0009]

However, in general, the side dam is preheated before casting, and is maintained at a high temperature of 1200 to 1400 ° C. during casting by the heat received from the molten steel. Therefore, the solid lubricant inserted through the side dam is also heated to at least 1000 ° C. or higher, and in the case of the lubricant supply structure as described above, a relatively inexpensive lubricant such as molybdenum disulfide or graphite. Can not be applied because it remarkably oxidizes, and the applicable lubricant is limited to BN or the like, which is very expensive. Therefore, the present invention solves such problems and enables casting for a long time by using a relatively inexpensive lubricant.

[0010]

The gist of the present invention for achieving such an object is as follows. (1) Injecting molten metal into a molten metal pool defined by a pair of cooling drums and a pair of side dams, and then continuously casting a thin plate while cooling and solidifying the molten metal on the rotating peripheral surface of the cooling drum. In the lubrication structure of the side dam of the twin roll type thin plate continuous casting machine, the solid lubricant is continuously supplied while being pressed against the sliding face of the cooling drum with the side dam. A water cooling means is provided in the guide pipe that guides to. Specifically, for example, the guide pipe may be a water cooling pipe.

(2) When a thin plate is continuously cast by using the thin plate continuous casting machine having the side dam lubrication structure of the above (1), reduction is performed while introducing a reducing gas or an inert gas into the guide pipe. The solid lubricant is continuously supplied to the sliding surface of the cooling drum with the side weir under the inert gas atmosphere or the inert gas atmosphere.

In the present invention, a guide pipe provided with a cooling means is used, or further, the inside of the guide pipe is made into a reducing gas atmosphere or an inert gas atmosphere, and the side dam ceramics are worn through the sliding surface of the end surface of the cooling drum. Since solid lubricant is supplied to the surface, inexpensive solid lubricant with excellent lubrication characteristics can be used even if it has poor heat resistance and oxidation resistance, and the increase in casting cost due to lubricant supply can be minimized. While suppressing, it became possible to perform stable casting for a long time by the lubrication effect.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the drawings. First, the side weir used in the present invention will be described with reference to FIGS. 1 and 2. In these drawings, the side weir 2a is covered on the outside by a side weir case 7, and the surface facing the end surface 18 of the cooling drum 1b has a heat insulating material 8, a base member 9, and a ceramic planted thereon. It is composed of the member 10. Ceramic member 1
0 is provided along the surface of the cooling drum end surface 18 that slides with the sliding surface 19, that is, the wear surface 20.
Of the lubricant supply port, that is, two positions 11 and 12 in the upper portion in FIG.

Guide pipes 15 provided with cooling means are provided at these supply ports so as to penetrate through the side dam 2a, and the solid lubricant 14 is inserted into the guide pipes 15. Further, the guide pipe 15 is provided with a gas introduction pipe 2 for flowing an inert gas or the like into the guide pipe.
1 is connected.

On the other hand, the lubricant pressing device is a cylinder 1
6 and a lubricant gripping portion 17 provided at the tip of the rod of the cylinder 16, the solid lubricant 14 is gripped by the lubricant gripping portion 17, and a sliding surface of the end surface of the cooling drum at a predetermined surface pressure. It is pressed to 19. The pressing device described here has only to press the solid lubricant against the sliding surface with a predetermined surface pressure, and an extension spring or the like can be used instead of the cylinder. In addition, 13 is a side dam vibrating device.

[0016]

EXAMPLES Next, the casting test results carried out by using the thin plate continuous casting machine having the above side dam lubrication structure will be described in detail. The material of the water cooling drum used in the experiment is SUS30
4, the material of the side weir ceramic member is BN: 50%,
AlN: 50%, the surface pressure of the side dam pressed against the sliding surface of the water cooling drum was 3 kg / cm ² , and the sliding speed of the ceramic member with respect to the sliding surface of the water cooling drum was 80 m / min.
The contact length between the ceramic member and the sliding surface of the water cooling drum end surface was 470 mm.

In such a thin plate continuous casting machine, a cylindrical solid lubricant made of graphite and molybdenum disulfide and having an outer diameter of 10 mm is used, and water is caused to flow in the water cooling pipe of the guide pipe.
Forced lubrication was performed while pressing the side weir against the sliding surface of the water cooling drum with the above pressing surface pressure.

The coefficient of friction between the sliding surface of the water cooling drum and the worn surface of the ceramic member was determined from the rotational torque value of the water cooling drum and is shown in FIG. It can be seen that the friction coefficient is significantly reduced in the present invention as compared with the case (comparative example) in which no solid lubricant is used (without).

On the other hand, FIG. 5 shows the amount of wear of the sliding surface of the end surface of the cooling drum at this time, and FIG. 6 shows the amount of wear of the wear surface of the ceramic member at this time, respectively when using a solid lubricant. The results measured at every 1 km distance are shown. From this result, it is understood that the wear amount of the sliding surface or the wear surface of the drum end surface and the ceramic member was remarkably reduced by the present invention compared with the comparative example.

This is because by supplying the solid lubricant through the guide pipe while water cooling the guide pipe, 1) improvement of lubrication effect against sliding between the cooling drum sliding surface and the ceramic member wear surface, This is probably because the effects of 2) lowering the surface temperature of the worn surface of the ceramic member, 3) suppressing the formation of irregularities on the sliding surface of the cooling drum, etc.

Next, using a thin plate continuous casting machine similar to that of the above-mentioned embodiment, under the same conditions, while flowing N ₂ gas in the guide pipe, and using a solid lubricant made of molybdenum disulfide. Was examined. As a result, also in this case, the same lubricating effect was obtained as in the case where the above-mentioned graphite was used as the solid lubricant and the guide pipe was water-cooled, but without flowing N ₂ gas into the guide pipe. .

On the other hand, when the graphite was used as a solid lubricant by using a guide pipe whose inside was in the atmosphere without water cooling, a rapid oxidation reaction occurred in the graphite, and the graphite was eroded and worn. It became a situation where it cannot be used as a solid lubricant. Further, it was found that the same result was obtained in the case of molybdenum disulfide, which cannot be used.

FIG. 7 shows the operating costs in the case where BN, graphite and molybdenum disulfide are used as solid lubricants, respectively. By using a relatively inexpensive solid lubricant according to the present invention, FIG. It can be seen that the increase in casting cost can be suppressed.

[0024]

As described above, according to the present invention, it is possible to extend the casting time while suppressing an increase in casting cost by using an inexpensive solid lubricant. In addition, the reduction of the friction coefficient also has the effect of preventing flapping of the side weir and extending the life of the end surface of the cooling drum, so that extremely stable casting can be performed for a long time.

[Brief description of drawings]

FIG. 1 is a perspective view showing a side dam structure of a thin plate continuous casting machine according to the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing a lubrication condition at a side weir of the thin plate continuous casting machine according to the present invention.

FIG. 3 is a perspective view of a thin plate continuous casting machine showing an outline of a twin drum method.

FIG. 4 is a diagram showing a relationship between a friction coefficient and a sliding distance between a cooling drum sliding surface and a side dam ceramic member.

FIG. 5 is a diagram showing a relationship between a wear amount of a cooling drum sliding surface and a sliding distance.

FIG. 6 is a diagram showing a relationship between a wear amount of a side dam ceramic member and a sliding distance.

FIG. 7 is a diagram showing a usage cost index of various solid lubricants.

[Explanation of symbols]

1a, 1b: cooling drum, 2a, 2b: side weir,
3: Hot water pool part, 4: Molten metal, 5: Metal ribbon,
6: Drum gap part, 7: Side weir case, 8:
Heat insulating material, 9: base member, 10: ceramic member,
11, 12: Lubricant supply port, 13: Vibration device, 1
4: Solid lubricant, 15: Guide pipe, 16: Cylinder, 17: Lubricant gripping part, 18: Cooling drum end surface, 19: Cooling drum sliding surface, 20: Ceramic member wear surface, 21: Gas inflow pipe.

Claims (2)

[Claims] 1. A molten metal is poured into a molten metal pool defined by a pair of cooling drums and a pair of side dams, and the thin metal is continuously cooled and solidified by the rotating peripheral surface of the cooling drum. A twin-roll type thin plate continuous casting machine for casting, which is a side dam lubrication structure, in which the solid lubricant is continuously supplied while being pressed against the sliding surface of the cooling drum with the side dam. A side dam lubrication structure for a thin plate continuous casting machine, characterized in that a water cooling means is provided on a guide pipe for guiding the sliding surface. 2. A thin plate continuous casting machine having a side dam lubrication structure according to claim 1 is used to continuously cast thin plates while introducing a reducing gas or an inert gas into the guide pipe. A continuous casting method for thin plates, characterized in that a solid lubricant is continuously supplied to a sliding surface of a cooling drum with a side weir in a gas atmosphere or an inert gas atmosphere.