JPH04285132A - Structure of conveying roll in continuous heat treatment equipment for strip - Google Patents

Abstract

PURPOSE:To provide the subject structure preventing walk, heat buckle, etc., to a strip. CONSTITUTION:In the conveying roll for continuously conveying the strip in a heat treatment furnace in order to apply the desired heat treatment to the strip, the conveying roll set at near inlet of the strip in the heat treatment furnace is made into hollow, and by forming a heat transfer layer composed of a good heat conductive body over the whole periphery in the inner face of a part, where contacts with the strip, the heat conduction to the width direction of conveying roll is made to good, i.e., the temp. difference in the width direction is reduced and heat crown is not remarkably different to any position in the width direction of conveying roll, and trouble of the walk, heat buckle, etc., to the strip, is not developed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is used in continuous strip heat treatment equipment for connecting the ends of dissimilar strips such as steel strips having different widths and continuously subjecting the strips to heat treatment such as annealing. The present invention relates to the structure of a conveyor roll for conveying a strip in a heat treatment furnace.

0002

2. Description of the Related Art Conventionally, strip continuous heat treatment equipment has been available in which a strip is continuously passed through a heat treatment furnace with conveyor rolls in order to perform heat treatment on the strip.

[0003] For example, in a continuous annealing treatment facility for steel strips as an example of such a heat treatment facility, a heating furnace, a soaking furnace, a primary cooling furnace, an overaging furnace, and a secondary cooling furnace are used as heat treatment furnaces. The steel strip is continuously transported by transport rolls (hearth rolls) installed inside the furnace and between each furnace.

0004

[Problems to be Solved by the Invention] For example, when there is a large difference between the internal temperature of the furnace and the external temperature or the internal temperature of the preceding furnace, such as in the heating furnace or primary cooling furnace of the above-mentioned continuous steel strip annealing treatment equipment, That is, if there is a large difference between the plate temperature of the strip being conveyed and the temperature inside the furnace, the temperature distribution will be non-uniform in the width direction of the conveying roll, especially near the entrance of the furnace. As a result, the amount of heat change in the radial direction, that is, the heat crown, varies significantly depending on the widthwise position of the conveyor roll, and if a wide strip is conveyed in this state, the strip may meander or buckle in the widthwise direction. There was a problem that the heat buckle was deformed.

Therefore, for example, Japanese Patent Publication No. 59-43981 discloses a structure in which a conveyor roll in a cooling furnace of a continuous steel strip annealing treatment facility is heated in accordance with the temperature of the strip.

However, the above structure can only be used for cooling furnaces and cannot be used for heating furnaces, and the structure is complex, and the heating device must be properly controlled at all times, so it is not possible to use it for heating furnaces. Costs tended to rise.

In view of the problems of the prior art, the main object of the present invention is to provide an inexpensive conveyor roll structure that can prevent strip walking, heat buckling, etc. in continuous strip heat treatment equipment. be.

[0008]

[Means for Solving the Problems] According to the present invention, the above-mentioned object is achieved by continuously transporting a strip with a plurality of transport rolls in a heat treatment furnace consisting of one or more furnaces, A conveyor roll structure of a continuous strip heat treatment facility for subjecting the strip to a desired heat treatment, wherein the conveyor roll disposed near the strip inlet in the heat treatment furnace is hollow and has a portion with which the strip can come into contact. This is achieved by providing a conveyor roll structure for continuous strip heat treatment equipment, which is characterized by having a heat transfer layer made of a good thermal conductor all around the inner surface of the strip.

[0009]

[Function] By doing this, the heat conduction in the width direction of the conveying roll is improved, and the temperature difference in the width direction is reduced.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below based on specific embodiments shown in the accompanying drawings.

FIG. 1a shows a schematic configuration of continuous strip annealing equipment to which the present invention is applied. A strip 2 is continuously supplied to this equipment from a payoff reel 1 installed at the line entrance, and the tip of the next strip is overlapped and welded to the end of the previous strip using a welding connection device 3, and then cleaned. It is cleaned by the device 4, the supply amount is adjusted by the inlet looper device 5, and then sent into the furnace for heat treatment. And heating furnace 6, soaking furnace 7,
The strip 2, which has been heat-treated according to a predetermined heat cycle after passing through a primary cooling furnace 8, an overaging furnace 9, and a secondary cooling furnace 10, is sent to a skin pass mill 12 after the amount of feed is adjusted by an exit looper device 11. . This skin pass mill 1
After being temper-rolled in step 2, it is divided into parts in inspection and refinement device 13.
Alternatively, the defective portion is removed and the treated strip 2 is wound onto the tension reel 14. Inside each furnace,
A large number of hearth rolls 15 are provided for applying appropriate tension to the strip 2 and causing it to run continuously.

FIG. 1b shows the change in plate temperature of strip 2 (solid line).
and the internal temperature (broken line) of each furnace 6 to 10. The strip 2 is heated in the first half (section A) of the heating furnace 6, passed through the soaking furnace 7, slowly cooled in the first half (section B) of the primary cooling furnace 8, and rapidly cooled in the second half. And an overaging furnace 9 and a secondary cooling furnace 10
It is gradually cooled down.

Here, the hearth rolls 17 to 21 near the entrance of the heating furnace 6 and near the entrance of the primary cooling furnace 8, where the difference between the temperature of the strip 2 and the temperature inside the furnace is relatively large, are provided with the A role structure is applied. That is, as shown in FIG. 2, which is a cross-sectional view of the hearth roll 17, the hearth roll 17 is hollow, and has a heat conductor made of pure copper as a good heat conductor over the entire circumference on the inner surface of the portion where the strip 2 can come into contact. A transmission layer 24 is provided. hearth roll 18
21 also have a similar structure to the hearth roll 17.

Incidentally, in reality, each furnace 6 to 10 has more hearth rolls 15 than shown in FIG. roll,
Or the temperature difference between the furnace temperature of the heating furnace 6 and the steel strip 2 is 100
It is sufficient that the roll structure based on the present invention is applied to the hearth roll at the position where the temperature is above .degree. In addition, in the primary cooling furnace 8, the temperature difference between the hearth roll, which is about 1/3 of the inside of the furnace, or the temperature inside the primary cooling furnace 8 and the steel strip 2 is 80%.
It is sufficient that the roll structure based on the present invention is applied to the hearth roll at the position where the temperature is above .degree.

FIGS. 3 and 4 show a case where the hearth roll according to the present invention is arranged near the entrance of the heating furnace 6 (solid line) and a case where a conventional hearth roll without a heat transfer layer is arranged (
The temperature distribution in the width direction of the hearth roll and the amount of heat crown at the dotted line) are shown. Here, point O is the center of the hearth roll (or steel strip), point P is the contact end of the steel strip with the hearth roll, and point E is the end of the hearth roll.

As shown in FIG. 3, the conventional hearth roll has a large temperature difference between its center points O and E, and a large temperature gradient near point P. Therefore, as shown in FIG. 4, the amount of heat crown is also significantly different between points O-P and points P-E. In contrast, in the hearth roll according to the present invention, the temperature difference between the O point and the E point is small, and the temperature gradient near the P point is also small. Therefore, between the O-P points and P
The difference in heat crown amount between point -E is also extremely small compared to conventional hearth rolls.

FIGS. 5 and 6 show a case where the hearth roll according to the present invention is arranged near the entrance of the primary cooling furnace 8 (solid line) and a case where a conventional hearth roll without a heat transfer layer is arranged (dashed line). The figure shows the temperature distribution in the width direction and the amount of heat crown of the hearth roll. In the case of this primary cooling furnace 8, as well as the heating furnace 6, the hearth roll based on the present invention has a smaller temperature difference between its center (point O) and the end of the hearth roll (point E) than the conventional hearth roll. Contact end of steel strip (P
The temperature gradient near point) is small, and between points O-P and P-E
The difference in heat crown amount between points is small.

[0018]

[Effects of the Invention] As is clear from the above explanation, according to the conveyor roll structure of the continuous strip heat treatment equipment according to the present invention, by simply providing a heat transfer layer on the inner surface of the hollow conveyor roll, the widthwise direction of the conveyor roll can be improved. Since the heat conduction is good and the temperature difference in the width direction is small, the heat crown does not vary significantly depending on the position in the width direction of the conveying roll, and problems such as walking and heat buckling do not occur in the strip.

[Brief explanation of the drawing]

1] FIG. 1a is a schematic configuration diagram of a continuous steel strip annealing equipment to which the present invention is applied, and FIG. 1b shows changes in strip temperature (solid line) in the continuous steel strip annealing equipment of FIG. 1a, and each heat treatment furnace. It is a graph showing the internal temperature (dashed line).

FIG. 2 is a schematic cross-sectional view of a hearth roll to which the present invention is applied.

[Fig. 3] Temperature distribution in the width direction of the hearth roll when the hearth roll according to the present invention is placed near the entrance of the heating furnace (solid line) and when the conventional hearth roll is placed (dashed line). show.

[Fig. 4] Heat crown amount in the width direction of the hearth roll when the hearth roll according to the present invention is arranged near the entrance of the heating furnace (solid line) and when the conventional hearth roll is arranged (broken line) shows.

[Fig. 5] Temperature distribution in the width direction of the hearth roll when the hearth roll according to the present invention is placed near the entrance of the primary cooling furnace (solid line) and when the conventional hearth roll is placed (dashed line) shows.

[Fig. 6] Heat crown in the width direction of the hearth roll when the hearth roll according to the present invention is arranged near the entrance of the primary cooling furnace (solid line) and when the conventional hearth roll is arranged (dashed line) Indicate quantity.

[Explanation of symbols]

1 Payoff reel 2 Strip 3 Welding connection device 4 Cleaning device 5 Input side looper device 6 Heating furnace 7 Soaking furnace 8 Primary cooling furnace 9 Overaging furnace 10 Secondary cooling furnace 11 Output side looper device 12 Skin pass mill 13 Inspection and finishing equipment 14 Tension reel 15 Hearth roll 17-21 Hearth roll 24 Heat transfer layer

Claims (3)

[Claims] 1. A continuous strip heat treatment facility for continuously conveying a strip with a plurality of conveyor rolls in a heat treatment furnace composed of one or more furnaces and subjecting the strip to a desired heat treatment. The conveyor roll has a conveyor roll structure, and the conveyor roll disposed near the strip inlet in the heat treatment furnace is hollow and has a heat transfer layer made of a good thermal conductor over the entire circumference on the inner surface of the portion that the strip can come into contact with. A conveyor roll structure of a strip continuous heat treatment equipment characterized by having the following. 2. The heat treatment furnace includes a heating furnace and a cooling furnace, and a conveyor roll disposed near the strip inlet in the heating furnace and the cooling furnace is configured to separate the conveyor roll having the heat transfer layer from the conveyor roll having the heat transfer layer. The conveyor roll structure of a strip continuous heat treatment equipment according to claim 1, characterized in that: 3. The conveyor roll structure for continuous strip heat treatment equipment according to claim 1 or 2, wherein the good thermal conductor is made of copper.