JPH0741868A - Continuous annealing furnace - Google Patents

Abstract

PURPOSE:To prevent overheat of the width edge surfaces of a strip caused by the overheat of the faced wall surface to burners in a non-oxidizing type continuous annealing furnace for steel strip using the flame burners. CONSTITUTION:In the furnace, temp. measuring instruments 4 are arranged in the width direction of the strip S, and the cooling devices 3 for cooling excess heating at the edge parts of the strip S based on the measured strip temp. distribution are attached to the side wall at the position faced to the burners 2. By this method, the overheat of the wall surface faced to the flames of the burners 2 is prevented and the overheat at the edge parts in the width direction of the strip S by radiation from the wall surface can be prevented, and the accurate temp. control in the width direction can be executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous annealing furnace for strip-shaped steel sheets by a non-oxidizing furnace system.

[0002]

2. Description of the Related Art Recently, as a continuous annealing furnace for strip steel sheets,
Published by The Iron and Steel Institute of Japan Nishiyama Memorial Technology Course As described in “Advances in continuous annealing technology for strips” in the continuous annealing technology course for zinc and aluminum plating, horizontal furnace,
A vertical type non-oxidizing furnace system has been widely adopted.

In the continuous annealing furnace for strip steel plates (steel strips) by the non-oxidizing furnace method, a burner using natural gas, LNG, COG or the like as a heating source is used as a heating source in both horizontal and vertical furnaces. A heating method by direct flame in one direction in the width direction is adopted, and the sum of H ₂ and CO amounts in the combustion gas is 5 by setting the air-fuel ratio to about 0.95.
%, The combustion state is controlled to be set so that only the rolling oil on the surface is removed without oxidizing the strip steel sheet.

However, in the case of direct flame heating with this burner, the length of the flame changes due to slight changes in the combustion ratio and air mixing ratio, and depending on the conditions, the side wall facing the burner is overheated, and this part is It becomes hotter than the side wall. When the strip-shaped steel sheet is passed through in such a situation, it is affected by radiation from the side wall of the furnace, the edge portion of the strip-shaped steel sheet has a higher temperature than the center portion, and plate temperature nonuniformity in the width direction occurs, In particular, for wide materials, the problem of quality becomes large due to non-uniform heating.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to prevent overheating of a width end face of a strip-shaped steel sheet due to overheating of opposing wall surfaces of the burner in a continuous annealing furnace for strip-shaped steel sheet by a non-oxidizing furnace system using such a flame burner. To provide an effective means for

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a continuous annealing furnace for strip-shaped steel sheets by a non-oxidizing furnace method using a flame burner, in which a temperature measuring device is provided in the width direction of the strip and based on the measured sheet temperature distribution. It is a continuous annealing furnace in which a cooling device for cooling the overheated portion of the edge portion of the strip-shaped steel sheet is attached to the side wall at a position facing the burner.

As the cooling device, a wall surface cooling device in an ordinary industrial kiln can be used.
A structure in which a cooling pipe for passing air or water as a cooling medium is arranged on the inner surface of a heat-resistant steel material such as SUS3163 steel having heat resistance that can withstand a slight reducing atmosphere burner flame is used, but air is used as the cooling medium. However, it is convenient in that the annealing conditions of the strip do not change rapidly.

[0008]

The overheat of the opposing wall surface due to the flame of the burner is prevented, and the overheat due to the radiation from the wall surface of the edge portion of the strip-shaped steel sheet in the width direction can be prevented, and the temperature control in the width direction can be accurately performed.

[0009]

EXAMPLE An example in which the present invention is applied to a non-oxidizing furnace portion of a continuous annealing furnace for plated steel sheets will be shown.

FIG. 1 is a schematic view of a continuous annealing furnace to which the present invention is applied, as seen from a plane.

In the figure, the continuous annealing furnace is arranged successively from the inlet 10 of the strip steel sheet S to a non-oxidizing furnace 1, a reducing furnace 11 and a cooling zone 12, and a heating burner 2
The cooling device 3 is arranged on the wall surface facing the. Reference numeral 4 denotes a plate thermometer arranged in the width direction of the strip S near the outlet of the non-oxidizing furnace 1 for measuring the temperature distribution in the width direction of the passing plate S. When the widthwise end of the strip becomes hotter than the central part and temperature nonuniformity occurs in the widthwise direction, the cooling control device 5 adjusts the opening / closing valve of the cooling air 6 to provide an air flow for cooling. Is increased to return to a predetermined uniform temperature distribution.

FIG. 2 shows a sectional structure of the non-oxidizing furnace 1 taken along the line AA of FIG.

As shown in the figure, the upper and lower surfaces of the strip S of the non-oxidizing furnace 1 are located at different positions,
The burner 2 is installed horizontally in the width direction,
Cooling devices 3 are embedded in the wall surfaces of the upper and lower burners 2 where the flames reach.

FIG. 3 shows a sectional structure of the non-oxidizing furnace 1 taken along the line BB of FIG. As shown in the figure, the temperature distribution in the width direction of the strip S is measured by a plate thermometer installed in the width direction of the strip S near the outlet of the non-oxidizing furnace 1.
When the edge portion in the width direction is overheated, the controller 5 adjusts the valve of 6.

FIG. 4 is a view showing a sectional structure of the cooling device 3, in which a cover 7 made of heat-resistant steel such as SUS316 is arranged on a wall surface 8 made of a refractory material, and cooling is performed on the back surface of the cover in the inner space. It has a structure in which an air conduit 9 is arranged.

FIG. 5 is an arrangement view of the cooling pipes in the cooling device as seen from the line CC of FIG. 4, and as shown in FIG. 5, the pipes are arranged in a meandering shape so as to obtain the cooling ability.

In the continuous annealing furnace in which the cooling device 3 is arranged, the burner 2 is actuated in accordance with the heating conditions of the continuous strip steel S to be passed. By constantly passing cooling air through the cooling devices 3 arranged on the inner wall surfaces of the respective burners 2 which face each other, overheating of the wall surfaces due to the flame of the burners 2 is prevented, and by the operation of the burners 2 under controlled conditions, It becomes possible to apply a predetermined controlled heating condition to the steel sheet steel sheet. Further, when the wall surface is overheated by the burner 2, it is possible to increase the cooling capacity by ventilation and restore the predetermined uniform temperature distribution.

[0018]

The present invention has the following effects.

(1) By making the temperature distribution in the strip width steel plate uniform in the width direction, it is possible to eliminate unevenness in the material in the width direction, uneven plating adhesion, uneven plating performance such as uneven plating only at the edges. .

(2) The range of manufacturing conditions for ensuring the required material and plating performance is expanded, and the range of operating conditions to be selected is expanded. In particular, the control becomes relatively simple due to the expansion of operating conditions for difficult-to-plate materials such as SUS type and high tensile strength.

[Brief description of drawings]

FIG. 1 shows a plan view of an oxidation-free continuous annealing furnace to which the present invention is applied.

FIG. 2 shows a cross-sectional structure of a burner and a cooling device portion viewed from the line AA in FIG.

FIG. 3 shows a cross-sectional structure of a plate thermometer installation portion viewed from the line BB in FIG.

FIG. 4 shows a cross-sectional structure of a cooling device.

FIG. 5 shows a layout of cooling pipes in a cooling device.

[Explanation of symbols]

 S strip 1 non-oxidizing furnace 2 burner 3 cooling device 4 plate thermometer 5 control device 6 valve (for opening / closing cooling air) 7 cover made of heat-resistant steel plate 8 refractory wall 9 cooling air conduit 10 annealing furnace inlet 11 reducing furnace 12 Cooling zone

Claims (1)

[Claims] 1. A continuous annealing furnace for strip steel sheets by a non-oxidizing furnace method using a flame burner, in which a temperature measuring device is provided in the width direction of the strip and overheating of the edge portion of the strip based on the measured strip temperature distribution. A continuous annealing furnace in which a cooling device for cooling the components is attached to the side wall at a position facing the burner.