JPH0751726A - Method for rolling by thermal insulation coil - Google Patents

Abstract

PURPOSE:To uniformize inside quality and to improve rough surface etc., of a roll in a finish rolling by insulating or heating the entire surface of the end face of a bar, in a heat treatment line in which a high temperature bar is coiled after roughing and the finish rolling is performed while the bar is uncoiled. CONSTITUTION:A head for insulating or heating an inner coiled part only is positioned close to a coil, and a bar coil 1, cradle roll 2, heating device 3 and position adjusting device 4 are provided. The diameter used for the heating device 3 is a size for covering about two thirds of the diameter of an average bar coil. The heating equipment is such that the heating device 3 can be moved to an optimum distance in accordance with the width of the bar. An LPG burner is used for heating, or an electric heating can be employed in view of the high responsiveness in control. Thus, the inside quality is uniformized, and the rough surface, etc., of a roll in a finish rolling is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil heat retaining hot rolling method.

[0002]

2. Description of the Related Art A conventional hot rolling line is roughly rolled to a bar having a thickness of about 30 to 50 mm as shown in FIG. Had been rolled into strips. However, since the finish rolling time is as long as 1 to 2 minutes, the temperature of the bar can be kept at 1000 ° C. or higher at the front end, but the rear end is cooled, causing problems such as an increase in rolling load and a change in internal quality. .

As a method for solving this problem, as shown in FIG. 3B, a bar after rough rolling is wound into a coil, and finish rolling is performed while unwinding the bar to prevent cooling of the bar. A method is disclosed in Japanese Patent Publication No. 51-26317. FIG. 4 shows an outline of the winding method.
Equipment that winds into a coil is called a coil box.

[0004]

In recent years, consumers have demanded that the inner quality in the coil width direction be made uniform, and efforts are being made to ensure the temperature at the ends and to make the inner quality in the width direction uniform. For example, there is a rolling line where an electric edge heater is installed in front of finish rolling, but it has a very large capacity (4000-5
Although it is an electric type edge heater of 000 kW),
Due to the high speed, sufficient temperature rise is not secured. The present invention provides a coil heat retaining hot rolling method in finish rolling of a hot rolling continuous line.

[0005]

The gist of the present invention is as follows. (1) In a hot rolling continuous line in which a high temperature bar is wound into a coil shape after rough rolling and finish rolling is performed while unwinding the bar coil, the entire end surface of the coil wound bar is kept warm or heated. A method for hot-rolling a coil to keep warm. (2) The coil heat retaining hot rolling method as described in (1), wherein only the inner winding portion of the end surface of the bar coil is kept warm or heated.

[0006]

In FIG. 2, the vertical axis represents the temperature when passing through the finishing inlet, the solid line represents the temperature in the central portion in the width direction, and the broken line represents the temperature at a position 25 mm from the end portion in the width direction. FIG. 2A shows a conventional method,
3A is an example of the finish inlet temperature, and FIG. 2B is an example of adopting the coil box of the conventional method (B).
In the case of (A), the temperature of the central portion decreases from the front end to the rear end with the passage of time. In the case of (B), due to the effect of the adoption of the coil box, the central portion temperature fluctuation is small over the entire length. However, (A),
(B) The temperature of the end portion in the co-width direction decreases with time.

As shown in FIG. 2B, in the coil box, the temperature at the central portion is almost uniform, but the temperature at the rear end portion drops extremely. Further, as for the end temperature, the temperature drop at the rear end part, that is, the inner winding part of the coil, becomes large for a while. In the present invention, in order to compensate for this, a head for keeping or heating only the inner winding portion is brought close to the coil as shown in FIG. This method requires an extremely small-scale heating device as compared to a large facility that heats the entire coil. In the figure, 1: bar coil,
2: cradle roll, 3: heating device, 4: position adjusting device.

Further, the heating capacity is long because the coil end faces are rotating at the same place, so that a heating device having a small capacity is sufficient as compared with the case where the coil is installed in front of the finish rolling. With such a device, it is possible to improve the temperature as shown in FIG. The temperature of the end portion of the inner winding portion, which has a large temperature drop, selectively rises, and the temperature is made uniform. As a result, the temperature drop at the rear end of the central temperature is also reduced. Here, the inner winding portion means a portion corresponding to 1/2 to 1/3 from the rear end in the length of the material to be rolled.

[0009]

[Examples] Table 1 shows the bar and coil specifications, rolling conditions, and an outline of a heating device of Examples. As shown in FIG. 1, the heating device has a diameter that covers about 2/3 of the average diameter of the bar coil. The heating equipment, according to the bar width,
The heating device 3 can be moved to an optimum distance. The LPG burner was used for heating because the equipment is small and the cost is low, but electric heating can also be used from the viewpoint of high responsiveness of control.

[0010]

[Table 1]

[0011]

EFFECTS OF THE INVENTION According to the present invention, the internal quality is made uniform and the roughening of the roll during finish rolling is improved.

[Brief description of drawings]

FIG. 1 is an explanatory view of a heating device of the present invention.

2 (A), (B), and (C) are charts of the temperature of the bar when passing through the finishing rolling mill entrance side.

3A and 3B are explanatory views of the configuration of a hot continuous line.

FIG. 4 is an explanatory diagram of a coil box.

[Explanation of symbols]

 1 bar coil 2 cradle roll 3 heating device 4 position adjusting device

Claims (2)

[Claims] 1. In a hot rolling continuous line in which a high temperature bar is wound into a coil shape after rough rolling and finish rolling is performed while unwinding the bar coil, the entire end surface of the bar wound in a coil shape is kept warm or heated. A method for hot-rolling a coil to keep warm. 2. The coil heat retaining hot rolling method according to claim 1, wherein only the inner winding portion of the end surface of the bar coil is kept warm or heated.