KR20040020541A - A cooling roll for twin roll-strip caster - Google Patents

Abstract

PURPOSE: Cooling rolls for twin roll strip caster are provided to extend life cycle of the cooling rolls by minimizing stress and strain of the body of the cooling rolls during casting and manufacture a slab of superior quality by preventing ripple from formed on the surface of cast slab. CONSTITUTION: In a twin roll strip caster comprising a pair of cooling rolls comprising a roll shaft(10a) in which a hollow cylindrical tube member(12) is fixed to an inner part of a main passageway(11) formed at a body central part, and on the outer circumferential surface of which first distribution region communicated with first connection passageway radially extended is depressingly formed, and a hollow cylindrical sleeve(10b) in which second distribution region communicated with the first distribution region by means of second connection passageway is sealed by an end plate, and cooling water channels(17) communicated with the second distribution region of left and right ends of the hollow cylindrical sleeve are circumferentially formed with being spaced apart from each other in a certain distance, and the body of which is formed of a copper material so that the outer circumferential surface of the hollow cylindrical sleeve is coated with a nickel layer; and edge dams adhered to both side surfaces of the cooling rolls to form a molten steel pool so as to manufacture a slab by rotating the cooling rolls oppositely to each other, the cooling rolls for the twin roll strip caster are characterized in that the cooling water channels of the sleeve are formed in the sleeve in such a way that inner diameter centers (C) are arranged along a circular imaginary line (P) having an outer diameter size corresponding to 95 to 96.8% of outer diameter (D) of the sleeve, wherein inner diameter (d) of the cooling water channels has a size corresponding to 0.64 to 1.667% of the outer diameter of the sleeve, and wherein a distance (W) between the cooling water channels is 95% of the inner diameter of the cooling water channels.

Description

Cooling roll for twin roll sheet casting machine {A COOLING ROLL FOR TWIN ROLL-STRIP CASTER}

The present invention extends the service life by minimizing the stress and deformation caused by the heat load when injecting molten metal between the water-cooled cooling rolls and casting a thin cast steel, and has a good quality cast without ripple on the surface of the cast steel It relates to a cooling roll for a twin roll sheet caster that can be manufactured.

In general, the thin plate casting process is a technology that can manufacture a plate directly from molten steel instead of making a steel sheet by rolling the slab or thin slab in the conventional casting process, a breakthrough technology that can omit the entire hot rolling process to be.

In other words, the thin plate casting process is a method of manufacturing a steel sheet having a sheet thickness of 1.4 to 4 mm by pouring molten steel to solidify two rolls interlocked with each other and applying a certain amount of hot deformation. The design of the machine or its elements is very important because all solidification processes in the c) must be completed and a uniform solidification and shape must be ensured over the full width of the roll while the hot molten steel undergoes this rapid cooling process.

As shown in FIG. 1, the twin roll type sheet casting machine 100 employed in the sheet casting process as described above has a pair of cooling rolls 1 and both sides thereof through the nozzle 4 through which the molten steel of the tundish 3 is immersed. The molten steel is supplied to form the molten steel pool 5 between the edge dams 2 attached thereto, and the cooling rolls 1 are rotated in opposite directions to heat the inside of the roll through contact between the roll and the molten steel. The molten steel is rapidly solidified to produce the cast steel 6.

In FIG. 1, reference numeral 7 denotes a meniscus shield for sealing the molten steel pool 5, and 8 denotes a brush roll.

And, as shown in Figure 2, the cooling roll (1) is composed of a roll shaft (10a) and a hollow cylinder-shaped sleeve (10b) assembled in the center of the length, one end is opened in the center of the roll shaft (10a) The main passage 11 is formed in which the other end is sealed, and the main passage 11 has a hollow so as to form an inflow passage 12a through which the coolant flows from the outside and a drain passage 12b through which the coolant finished cooling is discharged. Cylindrical tube member 12 is mounted on the outer circumferential surface of the roll shaft (10a) annular ring-shaped first distribution area 14 communicating with the first connecting passage 13 extending radially from the inlet passage (12a) To form a compound.

The second distribution area 16 communicates with the first distribution area 14 and the inclined first connecting passage 15 at both ends of the sleeve 10b assembled at the central portion of the roll shaft 10a. It is formed into an annular ring shape, which is sealed as an annular end plate (16a), while the outer peripheral body of the sleeve (10b) communicates with the second distribution area (16) of the left and right ends so that the coolant flows in one direction. A plurality of cooling water channels 17 are formed at regular intervals in the circumferential direction.

Accordingly, the cooling water flowing into one end of the main passage 11 is introduced into the closed end of the main passage 11 through the inlet passage 12a, and separated packing formed in the middle of the length of the drain passage 122b. By 18, the flow of the coolant reaches the first distribution zone 14, the second connection passage 15, and the second distribution region 16 through the first connection passage 13 in the vertical direction. The coolant in the second distribution zone 16 flows through the coolant channel 17 to the opposite second distribution zone 16, and the coolant in the second distribution zone 16 passes through the second connecting passage 15 and the first. Through the distribution zone 14 and the first connecting passage 13 to be circulated and discharged toward the drain passage 12b side of the tube member 12.

Here, the roll shaft 10a in which the main passage 11, the first communication passage 13, and the first distribution region 14 are formed is made of a general steel material, and the second connection passage 15 and the second distribution The sleeve 10b in which the region 16 is formed is made of a copper alloy material, while the outer peripheral surface layer of the sleeve 10b is coated with nickel.

On the other hand, while the molten steel of the very high temperature and the outer peripheral surface of the cooling roll (1) while solidifying the molten steel and at the same time giving a pressing force to the slab (6) in the twin-roll type sheet casting machine (100) to produce a cast of a very thin thickness The importance of the cooling roll 1 to determine the shape of the slab is very large.

Accordingly, since the design of the cooling roll 1 is a very important factor, the roll design may be the core of the sheet casting process. The design of the cooling roll (1) has to select the variables necessary for the roll design through the calculation of thermal stress and heat deformation, and the very large amount of heat from the molten steel enters the cooling roll while the cooling roll is in contact with the molten steel. As the temperature gradient increases, the thermal stress occurs significantly.

In addition, the cooling roll 1 is cooled by heat dissipation by the cooling water flowing in one direction through the cooling water channel 17 while not in contact with the molten steel. Thus, the cooling roll 1 is heated and heated during the casting process. Since the cooling is repeated, in particular, the sleeve 10b, which is the surface of the cooling roll 1, has a large temperature range in which heating and cooling are repeated, so that a large value of thermal stress is repeatedly changed. This may cause cracks on the surface of the sleeve 10b, which is the roll surface. If a crack occurs, the crack is transferred to the surface of the cast as it is, and the surface quality of the cast is poor, and in severe cases, it may cause a risk of leakage of the coolant.

Therefore, in order to improve the safety and surface quality of the operation, the cooling roll should be designed so that there is little possibility of cracking the surface of the roll. The manufacturing of the cooling roll 1 takes a lot of manufacturing cost and time, and the cooling roll 1 is When it is manufactured and used, short lifespan and problems in use will cause a great loss, so it should be carefully designed from the initial design to prevent loss and avoid problems when used. At this time, the first consideration in the design of the cooling roll (1) is the load applied to the roll, the design parameters will change according to the load.

That is, the load applied to the cooling roll 1 in the sheet casting process is the temperature of the molten steel, and as the thermal stress is generated and the deformation occurs in the cooling roll 1 by the molten steel temperature, it is transmitted to the cooling roll 1. The heat to be cooled must be cooled quickly, and for this purpose, as the cooling water is added to the cooling roll 1 to cool the roll, the arrangement, position and size of the cooling water channel formed in the cooling roll 1 are very important variables. do.

U.S. Patent 5651410 is for a cooling roll and proposed a cooling method or a path of cooling water flow, and U.S. Patent No. 5010947 suggests a method for accelerating slag solidification.

In addition, U.S. Patent No. 5996680 proposes a method of controlling the expansion amount by cooling the inside of the roll in a zigzag form, and U.S. Patent No. 5887644 proposes an assembly concept of the roll.

In addition, Japanese Patent Laid-Open No. 4-253551 relates to a method of cooling a roll, a cooling water direction and a cooling channel shape of a corner of the roll, and Japanese Patent Laid-Open No. Hei 1-1166862 and Japanese Patent Laid-Open No. 59-82149 disclose It is presented in relation to the body and the surface material.

The above-mentioned inventions relate to a cooling method and a material of the cooling roll 1, and the techniques mentioned so far about the shape and dimensions of the cooling water channel 17 of the cooling roll 1 and the position of the channel, etc. It is not disclosed.

Accordingly, the present invention has been proposed to solve the conventional problems as described above, the object of which is to minimize the stress and deformation of the cooling roll body during casting to extend the service life, ripple phenomenon on the surface of the cast slab It is to provide a cooling roll for a twin roll sheet caster that can produce a cast of excellent quality by preventing the.

1 is a configuration diagram showing a typical twin roll sheet caster,

Figure 2 is a cross-sectional view showing a cooling roll employed in a general twin roll sheet caster,

Figure 3 is a longitudinal sectional view showing a cooling roll for a twin roll sheet caster according to the present invention.

Explanation of symbols on the main parts of the drawings

1,1a ..... cooling roll 2 ........ edge dam

10a ... roll shaft 10b ... sleeve

11 ....... Main passage 12 ....... Tube member

12a ... intake passage 12b ... drainage passage

13 ....... first connecting passage 14,16 ....

17 ...... Coolant channel P ........ Circular virtual wire

D ....... Inner diameter W ........ Spacing

As a technical configuration for achieving the above object, the present invention,

A roll shaft having a hollow shaft cylindrical tube member fixedly disposed inside the main passage formed in the center of the body, and having a first distribution zone formed on the outer circumferential surface of the first distribution zone communicating with the first connection passage extending in the radial direction; and the first distribution zone and the first distribution zone. The second distribution area communicated through the two connecting passages is sealed as an end plate 16a, and the cooling water channel communicating the second distribution area at both ends is formed in a circumferential direction with a predetermined interval and is made of a copper material. A twin roll type forming a cast steel by forming a molten steel pool between a pair of cooling rolls consisting of a hollow-cylindrical sleeve coated with a nickel layer on an outer circumferential surface, and an edge dam attached to both sides thereof, and rotating the cooling rolls in opposite directions. In sheet casting machine,

The cooling water channels of the sleeve are provided in the sleeve so that the inner diameter centers are disposed along a circular imaginary line having an outer diameter corresponding to 95 to 96.8% of the outer diameter of the sleeve. By

Hereinafter, the present invention will be described in more detail.

Figure 3 is a longitudinal cross-sectional view showing a cooling roll for a twin-roll thin caster according to the present invention, as shown, the cooling roll (1a) of the present invention is mostly about 1000 ~ 1350 to match the width of the hot rolled coil sold It has a width W of about mm.

In addition, since the cooling roll 1a has to be filled with a molten pool differently from a roll for hot rolling to form a solidified shell, an outer diameter of the roll is made very large, and is typically configured to about 500 to 1500 mm.

When the cooling roll (1a) is subjected to an external heat load, less thermal stress and deformation should be made. Especially, after the cooling roll (1a) is rotated about five revolutions on the deformation side, the thermal equilibrium is achieved and the amount of expansion is almost reduced. . To this end, the size and position of the cooling water channel 17 is very important, and the material of the roll shaft 10a constituting the cooling roll 1a and the sleeve 10b assembled at the central portion thereof is also a very important factor.

That is, the roll shaft 10a of the cooling roll 1a is made of a general steel material, the sleeve 10b is made of a copper alloy having good thermal conductivity, and an outer circumferential surface of the sleeve 10b protects the copper alloy. It is coated by plating with nickel material.

The plurality of cooling water channels 17 for guiding the flow in one direction of the cooling water in the cooling roll 1a having such a configuration have an outer diameter corresponding to 95 to 96.8% with respect to the outer diameter D of the sleeve 10b. The inner diameter centers C are disposed along the circular virtual line P in the sleeve 10b.

Here, the outer diameter (D) of the sleeve (10b) is the same as the outer diameter of the cooling roll (1a), the center (O) of the outer diameter (D) of the sleeve (1a) coincides with the center of the circular virtual line (P). shall.

The inner diameter d of the coolant channel 17 circumferentially formed in the body in proximity to the outer circumferential surface of the sleeve 10b has a size of 0.64 to 1.667% with respect to the outer diameter D of the sleeve 10b. On the other hand, since the gap W between the coolant channel 17 and the adjacent coolant channel 17 is maintained in the processing, the distance W should be maintained as close as possible while having a predetermined interval within the processable range. Accordingly, the spacing W between the coolant channels 17 is about 95% of the inner diameter D of the coolant channel 17.

When the cooling water flow in the cooling roll 1a having such a configuration is supplied to one end of the main passage 11 formed in the roll shaft 10a as in the related art, the supplied cooling water is a tube member provided inside the main passage 11. It is transmitted to the first connection passage 13, the first distribution region 14, the second connection passage 15, the second distribution region 16 through the inlet passage 12a formed by (12). The cooling water in the two distribution zones 16 flows through the cooling water channel 17 to the second distribution zone 16 on the opposite side to heat the cooling to cool the cooling roll 1a.

Continuously, the coolant that is heat-exchanged while flowing in the coolant channel 17 in one direction passes through the second connecting passage 15, the first distribution region 14, and the first connecting passage 13 formed on the opposite side. It is discharged to the drain passage 12b side of (12).

Table 1 below shows the location of the cooling water channel, the sleeve body according to the change in the cooling water channel inner diameter, the temperature, deformation and stress of the surface coating layer.

Cooling water channel formation position compared to sleeve outer diameter 93% 95% 95% 96% 98% Cooling water channel inner diameter compared to sleeve outer diameter 2% 1.667% 0.64% 0.64% 0.64% Sleeve Surface Temperature (nickel) 430 ℃ 413 ℃ 402 ℃ 465 ℃ 411 ℃ Sleeve Body Temperature (Copper) 265 ℃ 252 ℃ 242 ℃ 232 ℃ 192 ℃ Sleeve Surface Deformation (Nickel) 0.157mm 0.145mm 0.137 mm 0.147 mm 0.104 mm Sleeve body deformation (copper) 0.149 mm 0.138 mm 0.130mm 0.137 mm 0.091mm Sleeve Surface Stress (nickel) 1.28E9 Pa 1.28E9 Pa 1.28E9 Pa 1.28E9 Pa 1.28E9 Pa Sleeve Body Stress (Copper) 1.28E9 Pa 1.28E9 Pa 1.28E9 Pa 1.28E9 Pa 1.28E9 Pa

The above calculation results are the result of the elastic analysis. In practice, however, elasto-plastic analysis can produce accurate results. In the elasto-plastic analysis, the stress will be about 1.5E8 Pa in nickel and the copper alloy will be 3.7E8 Pa. This is to reach the yield stress value of each material. Deformation will yield similar results from elastic or elasto-plastic analysis. In terms of temperature, copper is a precipitated alloy, so if it exceeds 350 ~ 400 ℃, the properties of the alloy are lost.

The relationship between stress and strain (T. Altan, S. I. Oh and H. L. Gegel, Metal Forming-Fundamentals and Applications, 1983, pp. 63) is given by Equation 1 below.

Where C (T) is the coefficient, m (T) is the strain sensitivity index, T is the temperature, Ts is the solidus temperature, and TL is the liquidus temperature.

In the result of Table 1, the position at which the cooling water channel 17 is formed is disposed along the circular virtual line P corresponding to 98% of the outer diameter of the cooling roll 1a, and the inner diameter d of the cooling water channel 17 is formed. If the cooling roll 1a has a size of 0.64% with respect to the outer diameter of the cooling roll 1a, a better result than the other results in terms of stress and temperature in the sleeve surface layer and the body can be obtained from Equation 1 above. Since the position is too close to the surface on the sleeve 10b side, the cooling effect between the cooling water channel 17 and the adjacent cooling water channel 17 is relative to the cooling effect on the upper portion of the cooling water channel 17 and the corresponding slab. Since a low temperature difference occurs, the outer circumferential surface of the sleeve 10b is deformed into a serpentine shape, which transfers the serpentine shape to the slab surface portion which is manufactured by forming a solidified shell while contacting the outer circumferential surface of the sleeve. It causes product defects.

On the other hand, the position where the cooling water channel 17 is formed is disposed along the circular virtual line P corresponding to 93% of the outer diameter of the cooling roll 1a, and the inner diameter d of the cooling water channel 17 is cooled. When the size of the roll 1a is 2% with respect to the outer diameter of the roll 1a, the results of stress, deformation and temperature are higher than those of other conditions. In particular, the stress of copper is high and it is not good in terms of fatigue life of the cooling roll 1a. It is judged that it is not an appropriate condition in design of a roll.

Accordingly, the formation position of the cooling water channel 17 is disposed along the circular virtual line P corresponding to 93 to 98%, preferably 95 to 96%, with respect to the outer diameter of the cooling roll 1a. The inner diameter d of the channel 17 is preferably provided with a size between 0.64 and 2%, preferably between 0.64 and 1.667%, relative to the outer diameter of the cooling roll 1a. In addition, the interval W of the coolant channel 17 may also be formed to a size corresponding to 95% of the inner diameter D of the coolant channel 17.

According to the present invention as described above, by forming the position and size of the cooling water channel formed in the width direction so as to be close to the surface of the sleeve flowing in one direction in relation to the sleeve outer diameter equal to the outer diameter of the cooling roll, the same conditions, It minimizes the stress and deformation of the sleeve body and the sleeve surface layer in contact with molten steel under the same heat load, thereby extending the service life of the cooling rolls and preventing ripple on the surface of the cast steel casting as it escapes between the casting rolls. Thus, the effect of producing a cast of excellent quality is obtained.

While the invention has been shown and described with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit or scope of the invention as set forth in the claims below. I would like to clarify that knowledge is easy to know.

Claims (3)

The hollow tube cylindrical tube member 12 is fixedly disposed in the main passage 11 formed in the center of the body, and includes a first distribution area 14 communicating with the first connecting passage 13 extending in the radial direction on the outer circumferential surface thereof. The formed roll shaft 10a and the second distribution zone 16 communicated with each other via the first distribution zone 14 and the second connection passage 15 are sealed as end plates 16a, and the left and right ends The cooling water channel 17 communicating the two distribution areas 16 is formed in a circumferential direction with a predetermined interval, and a pair of cooling rolls consisting of a hollow cylinder-shaped sleeve (10b) coated with a nickel layer on the outer surface of the body made of copper material (1) and a twin roll sheet caster for forming a cast steel (6) by forming a molten steel pool (5) between the edge dams (2) attached to both sides thereof, and rotating the cooling rolls (1) in opposite directions. To Cooling water channels 17 of the sleeve 10b are arranged with inner diameter centers C along a circular virtual line P having an outer diameter size of 95 to 96.8% with respect to the outer diameter D of the sleeve 10b. Cooling roll for a twin-roll sheet caster, characterized in that formed on the sleeve (10b). The method of claim 1, The inner diameter (d) of the cooling water channel (17) is a cooling roll for a twin roll thin caster, characterized in that the size of 0.64 to 1.667% with respect to the outer diameter (D) of the sleeve (10b). The method according to claim 1 or 2, The gap (W) between the cooling water channel (17) is formed in the size of 95% with respect to the inner diameter (D) of the cooling water channel (17).