JPS6118031Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a steel strip cooling device most suitable for continuous annealing equipment.

In continuous annealing equipment, a steel strip to be threaded is heated and soaked and then rapidly cooled in a cooling device to obtain a steel strip having desired quality.

In this cooling system, the steel strip after soaking is continuously passed through carrier rolls arranged vertically at appropriate intervals, and the steel strip is passed through plenum chambers provided on the front and back surfaces of the steel strip during the passing. It is designed to spray cooling gas to the The cooled gas after this blowing increases the temperature by absorbing the heat value of the steel strip, and is then sucked into a gas cooler placed at a predetermined distance in the width direction of the steel strip. After being cooled again, it is again forced into the plenum chamber by a circulating gas fan. It's becoming like that.

However, this cooling device has a problem in that the widthwise ends of the steel strip are supercooled due to the transfer of radiant heat to the gas cooler arranged at a predetermined distance from the widthwise ends of the steel strip. This supercooling occurs when the size of the steel strip to be heat treated is large and the amount of cooling heat is large (for example, when rapidly cooling from 800℃ to about 300℃), the gas cooler becomes large and the radiative cooling of the steel strip becomes significant. growing.

If the ends of the steel strip in the width direction are supercooled, the temperature distribution in the width direction of the steel strip becomes uneven, causing deformation of the steel strip, reducing the quality of the product and causing meandering of the steel strip. becomes large, making stable operation impossible.

The present invention takes the above-mentioned facts into consideration, and an object of the present invention is to provide a steel strip cooling device in which there is no risk of overcooling of the widthwise ends of the steel strip.

The steel strip cooling device according to the present invention achieves the intended purpose by preventing radiation cooling of the side portion of the steel strip by providing a shielding plate between the steel strip and the gas cooler.

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show a steel strip cooling device 10 of this embodiment, in which a casing 1 having a rectangular horizontal cross section is shown.
2 are arranged in the vertical direction. A steel strip 14 is passed through the middle of the casing 12 in the vertical direction. This steel strip 14 is the casing 12
It is wound around carrier rolls provided at the upper and lower ends (not shown) of the casing 12, and after being maintained at a predetermined temperature in a soaking zone (not shown), it is cooled within the casing 12 and transported out.

Inside the casing 12, as shown in FIG. 2, plenum chambers 16 and 18 are provided on the front and back surfaces of the steel strip 14 at a predetermined distance apart. A large number of air outlets 20 are formed on the side surfaces of these plenum chambers 16 and 18 facing the steel strip 14, so that cooling gas from within the plenum chamber is blown onto the steel strip 14 to cool the steel strip 14.

A pair of gas coolers 22 and 24 are provided on the side surface of the casing 12 in the width direction of the steel strip 14 and communicate with the casing 12. Therefore, these gas coolers 22 and 24 are arranged at a predetermined distance from the ends of the steel strip 14 in the width direction, and cool the steel strip 14 by sucking the cooling gas blown onto the steel strip 14 from the plenum chambers 16 and 18. It's becoming like that.

Circulating dust 26 and 28 are connected to these gas coolers 22 and 24, respectively, and the gas cooled by the gas coolers 22 and 24 is passed through a circulation fan 3.
0,32. These circulation fans 30,32 are in communication with the plenum chambers 16,18 to pump cooling gas from the circulation dust 26,28 to the plenum chambers 16,18.

Furthermore, shielding plates 34 and 36 are arranged inside the casing 12 between the widthwise ends of the steel strip 14 and the gas coolers 22 and 24, and both ends are supported by supporting hardware 37 to the plenum chambers 16 and 18, respectively. ing. As shown in detail in FIG. 3, these shielding plates 34 and 36 have a substantially rectangular horizontal cross section, and their longitudinal direction is perpendicular to the width direction of the steel strip 14.

In addition, the wall thickness of these shielding plates 34 and 36 in a horizontal section is greatest at the center and gradually decreases toward both ends. direction) to reduce resistance. Further, the horizontal cross-sectional longitudinal dimensions of the shielding plates 34 and 36 are designed to prevent the radiant heat from the steel strip 14 from being transmitted to the gas cooler 22 and the gas cooler 22.
4 and the steel strip 14 are so large that they cannot be seen directly from each other.

In this embodiment configured in this manner, the cooling gas injected from the plenum chambers 16 and 18 contacts the front and back surfaces of the steel strip 14 to cool the steel strip 14, and then flows in the width direction of the steel strip 14 to cool the steel strip 14. ,3
6, is sucked into the gas coolers 22, 24 and re-cooled, and is then pressure-fed by the circulation fans 30, 32 to the air outlet 2 of the plenum chambers 16, 18 again.
0 to the steel strip 14. Here, the radiation heat from the steel strip 14 to the gas coolers 22, 24 is blocked by the shielding plates 34, 36 and does not reach the gas cooler 22, so the steel strip 14 is cooled uniformly across its width, improving quality. do.

The radiation heat transfer Q in the above cooling state is expressed as follows: Q=4.88Φ(T ⁴ ₁ −T ⁴ ₂ ) (1). Here, Φ is the view factor and the overall heat transfer coefficient taking into account emicivity, T ₁ is the temperature on the high temperature side, and T ₂ is the temperature on the low temperature side.

Further, when the temperature of the steel strip is T _S and the surface temperature of the gas cooler is T _C , the above equation (1) becomes Q ₁ =4.88Φ(T ⁴ _S −T ⁴ _C ) (2). If the temperature of the shielding plates 34, 36 is _T1 , the heat from the steel strip is transmitted to the gas coolers 22, 24 via the shielding plates 34, 36, so _T1 > _Tc .
The amount of heat transferred from the steel strip is Q ₂ =4.88Φ(T ⁴ _S −T ⁴ _I ) (3). Comparing equations (2) and (3) above, since Q ₁ is larger than Q ₂ , the cooling of the steel strip is reduced by Q ₁ −Q ₂ , and supercooling at the ends in the width direction of the steel strip is eliminated.

In other words, the relationship between Q ₁ and Q ₂ is from the above equation, According to one experimental example, T _S =653℃, T _C =78
°C (without shielding plate), T _I = 393 °C,
Substituting these into equation (4), Q ₂ /Q ₁ =653 ⁴ -393 ⁴ /653 ⁴ -78 ⁴
= 0.87...(5), and a decrease in radiant heat transfer due to the shielding plate was confirmed.

Furthermore, if the surface of the shielding plate is covered with a stainless steel plate material with a bright finish, the emicivity will be reduced, so Φ ₂ /Φ ₁ = 0.13/0.18 = 0.72, so Therefore, the reduction of radiant heat transfer by the shielding plate is further ensured.

In addition to coating the shielding plate with a stainless steel plate, various brightening means can be considered in order to reduce emmissivity, and it is also possible to increase T _I by embedding a heater inside the shielding plate. A similar effect can be obtained.

Next, FIG. 4 shows a second embodiment of the present invention, in which a shielding plate 40 is provided. This shielding plate 40 includes a plurality of inclined plates 42 parallel to each other.
It is made up of.

These inclined plates 42 have slits 4 through which the gas flow after cooling is inclined at a predetermined angle with respect to the width direction of the steel strip.
4 are arranged so that a plurality of them are provided. Therefore, the gas flow after cooling the steel strip 14 is hardly resisted by the inclined plate 42, as shown by arrow B in FIG.
These inclined plates 42 are interposed between the gas cooler and the steel strip to prevent the steel strip from being radiatively cooled by the gas cooler.

As explained above, since the steel strip cooling device according to the present invention is provided with a shielding plate, the temperature distribution in the width direction of the steel strip becomes uniform and deformation is eliminated, and tracking of the steel strip is improved, resulting in stable operation and productivity. It has an excellent effect of improving

[Brief explanation of the drawing]

Fig. 1 is a side view showing an embodiment of the steel strip cooling device according to the present invention, Fig. 2 is a sectional view taken along the line shown in Fig. 1, Fig. 3 is a partially enlarged view of Fig. 2, and Fig. 4 is a main view. FIG. 4 is an enlarged view corresponding to FIG. 3 showing a second embodiment of the invention; 10... steel strip cooling device, 14... steel strip, 22,
24... Gas cooler, 34, 36, 40... Shielding plate.

Claims (1)

[Scope of utility model registration request] In a steel strip cooling device in which a gas cooler for cooling the steel strip is provided at a predetermined distance from the end in the width direction of the steel strip to be threaded, a shielding plate is provided between the steel strip and the gas cooler to cool the side portion of the steel strip. Steel strip cooling device that prevents radiation cooling.