JPH05200424A - Method for preventing electric spark generated at the time of heating steel plate by edge heater - Google Patents

Abstract

(57) [Abstract] [Purpose] In the case of locally heating both ends of the steel sheet in the width direction with an induction heating type edge heater, the flaws caused by electric sparks do not occur on the steel sheet surface, and the electricity generated when the steel sheet is heated by the edge heater. Provide a spark prevention method. When locally heating an end portion in the width direction of a steel plate 2 moving on a conveying roller 1 by an induction heating type edge heater 3, a taper roller is used as the conveying roller 1 of the edge heater 3 part, and the taper rollers are alternated. Place it in the opposite direction. Thus, the taper roller and the steel plate 2 are brought into point contact with each other, and when the steel plate is heated by the edge heater 3,
The electric spark generated by the leakage current flowing between the taper roller and the steel plate 2 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing electric sparks generated when a steel sheet is heated by an edge heater.

[0002]

2. Description of the Related Art When hot-rolling a steel sheet, the temperature of the steel sheet must be uniform in the width direction, but until the steel sheet is conveyed from a rough rolling mill to a finish rolling mill by a conveying roller. The temperature drop during the period is greater at the steel sheet width direction end portion than at the steel sheet center portion. Therefore, conventionally, in order to equalize the temperature in the plate width direction of the steel plate after rough rolling and before finish rolling,
As shown in FIG. 3, both ends of the steel sheet 2 in the width direction are locally heated by about 100 mm by the induction heating type edge heaters 3 arranged on both sides of the steel sheet 2 moving on the conveying roller 1 in the width direction. It was

[0003]

However, in the case of locally heating both ends of the steel sheet 2 in the width direction by the induction heating type edge heater 3, there are the following problems. That is, the conveyance roller 1 in the induction heating type edge heater 3 portion (the conveyance roller hatched in FIG. 3) has
As shown in FIG. 2, when the recess 1A is formed by local abrasion, the leakage current 4 flowing between the steel plate 2 and the conveyance roller 1 at the moment when the steel plate 2 leaves the conveyance roller 1 causes the steel plate 2 and the conveyance roller 1 to move. There is a risk that sparks will occur between the two and the crater-like flaws on the surface of the steel plate 2. The leakage current 4 flowing between the steel plate 2 and the conveying roller 1 is caused by the conveying roller 1
Flows even if is electrically isolated. The flaws thus generated on the two surfaces of the steel sheet remain even after finish rolling,
The commercial value of the rolled coil is significantly impaired.

Therefore, according to the present invention, in the case where both end portions in the width direction of a steel sheet are locally heated by the induction heating type edge heater, the electric power generated at the time of heating the steel sheet by the edge heater does not cause flaws due to electric sparks on the steel sheet surface. It is to provide a spark prevention method.

[0005]

According to the present invention, when a widthwise end of a steel sheet moving on a conveying roller is locally heated by an induction heating type edge heater, a taper roller is used as the conveying roller of the edge heater portion. use,
The taper rollers are alternately arranged in opposite directions, thus
It is characterized in that the taper roller and the steel plate are brought into point contact with each other to prevent an electric spark generated by a leakage current flowing between the taper roller and the steel plate when the steel plate is heated by the edge heater.

Next, an embodiment of an electric spark preventing method of the present invention which occurs when a steel sheet is heated by an edge heater will be described with reference to the drawings. FIG. 1 is a front view showing an embodiment of an electric spark prevention method of the present invention which occurs when a steel plate is heated by an edge heater, and FIG. 2 is a partially enlarged view of FIG. As shown in FIG. 1, in the present invention, when locally heating the widthwise end portion of the steel plate 2 moving on the transport roller 1 by the induction heating type edge heater 3,
A feature is that a taper roller is used as the conveying roller 1 of the edge heater 3 and the taper rollers are alternately arranged in opposite directions.

As described above, by using the taper roller as the conveying roller 1 and arranging the taper rollers alternately in the opposite directions, as shown in FIG. It passes through the edge heater 3 portion while contacting. Thus, since the steel plate 2 and one taper roller are in contact with each other only at one point, no leakage current flows if the taper roller is electrically insulated. Therefore, no flaws due to electric sparks occur on the two surfaces of the steel sheet.

[0008]

As described above, according to the present invention, when the both ends of the steel sheet in the width direction are locally heated by the induction heating type edge heater, the taper roller is used as the steel sheet conveying roller in the edge heater portion. By using it, there is a useful effect that electric spark due to leakage current generated between the steel plate and the conveying roller can be prevented.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of an electric spark prevention method of the present invention that occurs when a steel plate is heated by an edge heater.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a plan view showing a conveyance roller provided with an induction heating type edge heater.

FIG. 4 is a schematic front view showing the flow of leakage current.

[Explanation of symbols]

 1: Transport roller, 1A: concave part, 2: steel plate, 3: edge heater, 4: leakage current.

Claims (1)

[Claims] 1. When locally heating an end portion in the width direction of a steel sheet moving on a conveying roller by an induction heating type edge heater, a taper roller is used as the conveying roller of the edge heater portion, and the taper rollers are alternately arranged. It is arranged in the opposite direction, thus preventing the electric spark generated by the leakage current flowing between the taper roller and the steel plate when the taper roller and the steel plate are brought into point contact with each other to heat the steel plate by the edge heater. A method for preventing electric sparks generated when a steel sheet is heated by an edge heater.