JPH04162902A - Heating device for preheating rolling roll - Google Patents

Abstract

PURPOSE:To prevent thermal eccentricity by situating the tip part of steam discharging pipe in roll in the lower part inside the roll in the device for preheating rolling roll. CONSTITUTION:In a heating device with which the roll is preheated by its heat by introducing high-temp. steam into the interior of the rolling roll 1, steam that thermal transmission is finished and its liquefied matter are discharged from the internal pipe 6 through a discharging pipe 3 in the air by the siphon principle at the time of preheating the inside surface of the roll 1 by introducing steam along the axis of the roll 1 through a steam pipe 2, joint 4, external pipe 5 for introducing steam and internal pipe 6 for discharging its liquefied matter. In this way, this method has effects that liquid hardly stays in the region 7 where steam is introduced, uniform thermal transmission can be performed over the inside surface of roll, thermal eccentricity is prevented and thickness fluctuation isn't generated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the profile of a rolled plate (thickness distribution in the width direction).
This invention relates to a heating device for preheating rolling rolls to control flatness (planar shape).

[Conventional technology]

In rolling a metal plate, keeping the thickness of the plate constant in the width direction is an extremely important issue from the viewpoint of improving yield. In order to achieve this objective, various methods for controlling roll crown have been proposed.

As an example, high temperature steam is introduced into the inside of a rolling roll.
A technique for rolling a rolled plate by transmitting the heat to the inner surface of the roll to preheat the roll so that the heat crown of the roll reaches a required amount is found in JP-A-59-199108.

[Problem to be solved by the invention]

However, in the case of the above-mentioned technique, a phenomenon occurs in which the steam that has transferred heat to the inner surface of the roll liquefies, and liquid accumulates in the lower part of the roll. As a result, there is a difference in the amount of heat transfer between the inner surface of the roll that is in contact with the liquid and the inner surface of the roll that is in contact with the steam, and accordingly there is a difference in the thermal expansion of the roll. As a result, thermal eccentricity occurs in the rolls, and when rolling is performed using such rolls, variations in the thickness of the rolled plate occur, posing a major quality problem.

[Means to solve the problem]

In view of this, as a result of various studies, the present invention has developed a heating device for preheating rolling rolls that minimizes the thermal eccentricity generated in the rolls when preheating the rolls by introducing high-temperature steam into the rolls. .

That is, the present invention introduces high pressure steam into the inside of the rolling roll,
In a heating device that preheats the roll by transmitting the heat to the inner surface of the roll, a discharge pipe is installed along the axis of the roll to discharge steam or its liquefied product to the outside, and the tip of the discharge pipe is always connected to the roll. It is characterized by being located at the lowest part of the interior.

[For production]

As described above, in order to discharge steam introduced into the roll or its liquefied product, the present invention includes a discharge pipe installed inside the roll from the axial direction of the roll, and the tip of the discharge pipe positioned at the lowest part within the roll. This is characterized by the fact that when the steam that has transferred heat with the inner surface of the roll liquefies and accumulates at the bottom of the roll, the liquefied material is sucked up from the discharge pipe using the siphon principle and discharged to the outside. .

Therefore, only a small amount of liquid accumulates inside the roll. As a result, the steam comes into contact with the inner surface of the roll in a negative manner and heat transfer occurs, so that thermal eccentricity of the roll does not occur.

〔Example〕

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

Figure 1 shows an embodiment of the device of the present invention. Outer tube, (6
) indicates an inner pipe for discharging steam and its liquefied substances, (7) indicates a steam introduction area, and a joint (4) to which a steam pipe (2) and a discharge pipe (3) are attached is provided at one end of the roll (1). A steam introduction outer pipe (5) extending from the joint (4) to the steam introduction area (7) in the convex rule (1) and an inner pipe (6) for discharging steam and its liquefied products, such as a siphon pipe, are provided. Piping (2
) is introduced into the steam introduction region (7) through between the outer tube (5) and the inner tube (6), and heat is transferred to the inner surface of the roll (1).

After heat transfer, the steam and its liquefied product pass through the inner pipe (6) and the discharge pipe (3) using the resiphon principle, and are released into the outside air. At this time, it is important to note that in order to make use of the siphon principle, it is desirable to make the pressure in the inner pipe (6) and the discharge pipe (3) lower than the steam pressure, and the pressure difference is approximately 0.
．． It is preferable to set it to 1 kg/cd or more.

In order to enable heating even while the rolls are rotating, it is desirable that the joint be a rotary joint with a fixed inner tube. In that case, while the roll is rotating, the steam piping,
Outer pipe, discharge piping.

The tip of the inner tube can always be positioned at the bottom of the inner surface of the roll without rotating the inner tube.

In addition, in the above embodiment, a double pipe was used to introduce steam from one side of the roll and discharge it, but the same structure can be used in which steam is introduced from one side of the roll and steam and its liquefied product are discharged from the other side. effective. Furthermore, by introducing dry air or the like instead of steam after heating is completed, the steam introduction area can be dried, and the inner surface of the roll can be rust-proofed.

The temperature difference between the upper and lower surfaces of the roll obtained in the above example is shown in FIG. 2, and the amount of eccentricity of the roll is shown in FIG. The roll is a work roll for hot finishing rolling with a diameter of 700 mm and a barrel length of 2.
900 mm, the heating medium is water vapor at 130 °C,
Heating was performed for 1 hour.

As is clear from Fig. 2, the temperature difference between the upper and lower surfaces of the roll is approximately 7°C in the conventional device, whereas it is approximately 1°C in the device of the present invention, indicating that the difference in heat transfer between the upper and lower surfaces is approximately 1°C. It turns out that there are almost no. In addition, as is clear from Fig. 3, the roll eccentricity is 50 μm or more in the conventional device, which poses a serious problem in terms of the accuracy of the product plate thickness, but in the present invention, the roll eccentricity is 50 μm or more.
It is 0 μm or less, which is a level that does not pose much of a problem.

[Effects of the Invention] As described above, according to the present invention, almost no liquid accumulates in the steam introduction region inside the roll, and heat transfer is carried out in a similar manner to the inner surface of the roll, making it difficult to cause thermal eccentricity. It has remarkable industrial effects, such as no variation in plate thickness due to thermal eccentricity even when rolling is carried out.

[Brief explanation of drawings]

Figure 1 is a partially cutaway side sectional view of an embodiment of the apparatus of the present invention, Figure 2 is a graph showing the roll surface temperature when the apparatus of the present invention and the conventional apparatus are used, and Figure 3 is the apparatus of the present invention. It is a graph showing the amount of roll eccentricity when using a conventional device. 1...Roll 2...Steam pipe 3...Discharge pipe 4...Joint 5...Outer pipe for introducing steam 6...Inner pipe for discharging steam and its liquefied products 7...Steam introduction Area Figure 2 °C Figure 3

Claims (1)

[Claims] A heating device that introduces high-temperature steam into the inside of a rolling roll and transmits the heat to the inner surface of the roll to preheat the roll. 1. A heating device for preheating a rolling roll, characterized in that the distal end of the discharge pipe is always located at the lowest position within the roll.