JPH025804B2 - - Google Patents

Description

Detailed Description of the Invention Technical Field Heat treatment of metal strips, especially cold strips, especially for guiding the winding movement of the strips when the strips are continuously heated or cooled in a continuous annealing furnace. In addition, a heat conductive roll is advantageously used to transfer heat during this winding contact, and the following regarding such a heat conductive roll is located in the field of technology related to heat treatment of metal strips. ing.

Problem: This type of heat transfer roll generally has a hollow roll body, and conducts a heating or cooling heat medium, that is, a heat medium or a refrigerant (collectively referred to as a heat medium) through the hollow inside of the roll body. Heat is exchanged between the metal strip and the metal strip that is wound around the roll cylinder and comes into contact with it. Figure 1 shows a typical example of a straight body type roll (hereinafter referred to as an SB roll), where 1 is the roll body, 2 is the cavity inside the body, and 8 is the heat medium conducted in the cavity inside the body. be.

When the rotational speed of the SB roll increases, the relative velocity between the inner surface of the internal cavity 2 and the heat medium 3 increases, and the heat transfer coefficient α between the two increases accordingly. In other words, the higher the passing speed of the metal strip, the better the transfer of heat to and from the metal strip, that is, the heat exchange efficiency.

However, on the other hand, when a certain speed is reached, the heat transfer coefficient α tends to decrease, and it has been found that this tendency depends on the liquid level L of the heat medium flowing through the internal cavity 2. .

As shown in FIG. 2 as an example of the results of the experiment, it has been found through the experiment that the higher the liquid level L is, the more the above-mentioned decrease occurs in the low rotation range.

Purpose of the Invention According to the experimental results shown in FIG. 2, it is possible to maintain a linear relationship between the heat transfer coefficient according to the roll rotation speed V in a higher rotation range. The purpose of this invention is to ensure and sustain the following.

Structure of the Invention The above object can be advantageously achieved by a structure based on the following matters.

That is, it has a hollow roll body, a heat medium for heating or cooling is conducted inside the body, and the heat transfer roll for a metal strip is used to heat or cool a metal strip wound around the outer periphery of the roll body. In addition to an inlet and an outlet for conducting the heat medium into the roll body, this heat conduction roll for metal strip is provided with a gas pressure application port for pressurizing and calming the liquid level of the heat medium in the roll body.

By applying this gas pressure to the liquid level of the heating medium in the cavity inside the roll body, the level can be changed to 0.5d for the cavity inner diameter d, an example of which is shown in FIG.
Since a liquid level over a height of 200 mm is maintained continuously, the heat exchange efficiency of the heat transfer roll can be estimated directly from the roll rotation speed, which is useful in controlling heat treatment operations of metal strip.

Now, let us take as an example that the heating medium 3 conducted through the internal cavity 2 of the SB roll mentioned above in Fig. 1 is usually mixed with a gas phase in the cavity 2, and this gas phase accompanies the outflow of the heating medium 3. Since the liquid level of the heating medium 3 rises each time it is partially discharged, it has not been possible to maintain the level constant.

On the other hand, as shown in FIG. 3 illustrating the main parts near the end of the roll body 1, pressurized gas is supply.

In the figure, 6 indicates the introduction piping connection port for the heat medium 3, 7 indicates the liquid passage port of the journal section, and 8 indicates the labyrinth packing on the outer periphery of the journal section, and pressurized gas is applied to the intermediate position of the labyrinth packing 8. A port 9 is provided, and 10 is an airtight seal at both ends of the rotary joint 5.

Therefore, the heat medium 3 is introduced into the internal cavity 2 of the roll cylinder 1 from the introduction piping connection port 6 through the liquid passage port 7, and is discharged from an outlet not shown in the figure while being circulated. Of course, heat exchange between the metal strip and the metal strip takes place on the surface of the metal strip.

At this time, the pressurized gas passes through the labyrinth packing 8 from the application port 9 and enters the internal cavity 2 together with the heating medium 3, and the pressure causes the internal cavity 2 to
It is clear that the liquid level of the heating medium 3 within the heating medium 3 can be maintained appropriately, and it goes without saying that the pressure of the pressurized gas must slightly exceed the pressure of the heating medium 3 here.

Note that the pressurized gas can be prevented from leaking by airtight seals at both ends of the rotary joint 5, and leakage of the heat medium 3 can be completely prevented by such two-stage seals.

Effects of the Invention According to the present invention, the exchange of heat between the heat conductive roll and the metal strip running in contact with the circumference of the heat conductive roll, that is, the heat exchange efficiency, is determined according to a linear relationship between the roll rotation speed and the heat transfer coefficient. Since it can be easily estimated from the rotational speed, it is very useful in managing the heat treatment of metal strips.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an SB roll, FIG. 2 is a graph showing the effect of roll rotation speed on heat transfer coefficient, and FIG. 3 is a cross-sectional view of main parts showing an embodiment of the present invention. 1... Roll cylinder, 2... Cavity inside the cylinder, 3... Heat medium, 6... Heat medium introduction piping connection port, 9... Pressurized gas application port.

Claims (1)

[Scope of Claims] 1. A heat conductive roll for metal strip, which has a hollow roll body, conducts a heating or cooling heat medium through the inside of the body, and controls the heating or cooling of the metal strip wound around the outer periphery of the roll body. In addition to an inlet and an outlet for conducting the heat medium into the roll body, a heat conduction roll for metal strip is provided with a gas pressure application port for pressurizing and calming the liquid surface of the heat medium in the roll body. .