JPS627249B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for equalizing the temperature of rolls used in an apparatus for heat treating metal strips including hot rolling, and a roll for carrying out the method.

Traditionally, when metal strips are continuously heat treated,
For example, in the continuous annealing treatment of common steel strips, a vertical continuous annealing furnace as shown in FIG. 1 is used.

In FIG. 1, a strip 1 enters a furnace F through a furnace inlet 2, is suspended from a large number of rolls 9 arranged in a staggered manner in the furnace F, and is annealed in a reducing atmosphere gas while meandering. A heating zone 4 heated by a radiant tube (or electric heater) 3, a soaking zone 5 maintained at the annealing temperature for the required time, and a cooling rate from the annealing temperature of about 450 to 480℃ based on the metallurgically required cooling rate. It passes through an annealing zone 6 where it is slowly cooled, a quenching zone 7 where it is rapidly cooled down to approximately 90°C or less by being blown with the cold atmospheric gas, and then exits through an outlet 8 after passing through a thermal cycle as shown in Figure 2. .

The roll 9 described above is configured as shown in FIG. 3, for example. In FIG. 3, 10 and 10' are furnace wall refractories of the furnace F, 11 and 11' are roll bearings, and 12 is a roll drive motor.

In FIG. 3, the strip 1 is shown with so-called normal tracking in which it advances to the normal position in the center of the furnace F, but in actual operation, tracking failures often occur, and in severe cases, the side wall refractory material 10, 10', the strip 1 comes into contact with the strip 1, damaging the strip 1, lowering its commercial value, and damaging the oven wall.

For this purpose, the surface of the roll 9 is provided with a so-called crown 2e, with the diameter of the end portion of the roll 9 being slightly smaller than the diameter of the center portion of the roll 9, as shown in FIG.

The effect of this crown is, for example, when strip 1 is shifted to the right as shown in Figure 4A.
As shown in FIG. 4B, _which is a plan view in the direction of arrow a _{in FIG .} Then, from the relationship of the contact area, P ₁ >P ₂ and Q ₁ >Q ₂ , so a force of Q ₁ -Q ₂ acts on the strip 1 to return the strip 1 to its normal position.

Another way to prevent tracking failures is to use so-called steering rolls, which move multiple roll bearings horizontally in opposite directions, but the structure is complicated and expensive. Therefore, there is a limit to the number of installations, and steering rolls alone have not been able to achieve sufficient effects.

By the way, there is a proper value for the crown amount of the roll, and if the crown is more than necessary, the contact between the roll and the strip will be poor, and the tracking correction effect will be reduced. Furthermore, even when a roll with an appropriate crown is used, for example, in heating zone 4, the furnace temperature is approximately 850°C;
Since the temperature of the strip 1 gradually rises from room temperature, the temperature of the strip 1 is still quite low especially near the inlet 2 of the heating zone 4, and near the center of the roll 9 that comes into contact with the low temperature strip 1, heat is transferred to the strip 1. The crown amount is reduced due to the difference in thermal expansion of the roll 9 diameter due to this temperature difference, and not only is it impossible to maintain an appropriate crown amount, but in some cases There is a drawback that an inverted crown occurs in which the diameter of the roll 9 is larger at the end than at the center, which impairs the tracking correction effect.

The present invention has been made in order to eliminate the above-mentioned drawbacks. A pipe is provided in the axial direction, and a heat medium is sealed in the heat pipe, and the heat medium evaporates in the high temperature part of the roll and condenses in the low temperature part, thereby circulating and uniformizing the temperature in the width direction of the roll. (2) providing one or more heat pipes in the axial direction on the outer periphery of the roll; This invention relates to a roll for a metal strip heat treatment apparatus characterized by enclosing a heating medium that condenses in a low-temperature part.According to the present invention, problems caused by the above-mentioned temperature difference are reduced and good tracking is ensured. be able to.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a diagram for explaining one embodiment of the present invention, and FIG. 6 is a sectional view taken along the line -- in FIG. 5.

In FIGS. 5 and 6, a large number of heat pipes 20 are provided in the axial direction on the outer circumference of the roll 9. The heat pipe 20 should be attached to the roll 9 in such a way that the heat transfer resistance between the heat pipe 20 and the roll 9 is as small as possible. It can be attached to the roll 9 by the following method.

Alternatively, a hole can be made directly in the axial direction on the outer peripheral wall of the roll 9 and this hole can be used as a heat pipe, or a concentric groove can be made on the outer periphery of the roll 9 as shown in FIG. heat pipe 20
It is also possible to do this.

The heat pipe 20 has a heating medium that evaporates in the high temperature part of the roll 9 and condenses in the low temperature part. , the low temperature part
Since it is 100-650℃, it evaporates at 700-850℃,
A heating medium that condenses at 100-650°C is enclosed. As the heating medium, the following can be used, for example.

Biphenyl (boiling point 254℃, critical temperature 528℃, critical pressure 41.4 atm) Decalin (boiling point 185-195℃, critical temperature 408-419
) Quinoline (boiling point 238°C, critical temperature 509°C) Terphenyl (boiling point 220°C, critical temperature 652.8°C) Sulfur (boiling point 444.6°C, critical temperature 1040°C) Figure 8 shows a heat pipe filled with the above heating medium 21. FIG.

In FIG. 8, the heat medium 21 is in a liquid state at a low temperature section, but evaporates at a high temperature section, and during this evaporation, a large amount of vaporization heat is taken away from the surroundings of the high temperature section pipe.
Next, the vaporized heat medium reaches a low temperature section where it condenses and liquefies, releasing a large amount of heat at this time. Therefore, by moving and circulating within the heat pipe 20 as described above, the heat medium 21 carries not only sensible heat but also large latent heat for vaporization or condensation.
The amount of heat transfer is much larger than in the case of normal movement and circulation of heat medium without phase change, and extremely excellent heat transfer ability is exhibited.

Also, roll 9 is at the line speed of strip 1.
Since it rotates at a circumferential speed of 5 to 10 m/sec. corresponding to 300 to 600 m/min., the heating medium 21 in the heat pipe 20 is subjected to centrifugal force due to the rotation of the rolls, and the liquid heating medium is The vaporized heating medium occupies a portion close to the outer periphery of the inner roll, and the vaporized heating medium occupies a portion close to the center, promoting movement and circulation of the heating medium and, as a result, promoting heat transfer.

As a result of the heat transfer as described above, the temperature in the axial direction of the roll 9 has a distribution as shown in FIG. 9, for example. FIG. 9 shows the temperature distribution at the end of the roll 9. When there is a strip in the negative direction from the horizontal axis O and the curve α is for a conventional roll,
Curve β is the case according to the present invention. As is clear from FIG. 9, according to the present invention, the roll temperature can be made uniform.

The present invention described above can be applied not only to the heating zone roll described above, but also to a cooling zone roll as shown in FIG. 10 to equalize the temperature of the roll 9. Not limited to
It can be applied to heat treatment of stainless steel strips and other various metal strips.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional vertical continuous annealing furnace for ordinary steel strip, Fig. 2 is a diagram showing the thermal cycle of continuous annealing of ordinary steel strip, and Fig. 3 is a diagram showing the thermal cycle of continuous annealing of ordinary steel strip. A schematic diagram showing one configuration example, FIG. 4A is a diagram for explaining a tracking defect situation of the strip that occurs during actual operation of the roll shown in FIG. 3, and FIG. 5 is an explanatory diagram of an embodiment of the roll according to the present invention, FIG. 6 is a cross-sectional view taken along the line -- in FIG. 5, and FIGS. FIG. 8 is a diagram schematically explaining the action of the heat pipe according to the present invention, and FIG. 9 is a diagram explaining the effects of the present invention.

Claims (1)

[Scope of Claims] 1. One or more heat pipes are provided in the axial direction on the outer periphery of a roll for a metal strip heat treatment apparatus, a heat medium is sealed in the heat pipe, and the heat medium is heated to a high temperature of the roll. 1. A method for equalizing the temperature of a roll for a metal strip heat treatment apparatus, characterized in that the temperature of the roll in the width direction of the roll is uniformized by evaporating in one part and condensing in a low temperature part, thereby making the temperature uniform in the width direction of the roll. 2. In a roll for a metal strip heat treatment apparatus, one or more heat pipes are provided in the axial direction on the outer periphery of the roll, and a heat medium that evaporates in the high temperature part of the roll and condenses in the low temperature part is contained in the heat pipe. A roll for metal strip heat treatment equipment, characterized in that the roll is encapsulated with.