JPH07265932A - Roll for transporting steel sheet - Google Patents

Abstract

PURPOSE:To provide a steel-sheet transporting roll which eliminates generation of sparks between a steel sheet and a roll in the case of induction heating of the end of a steel sheet and which has a long roll life. CONSTITUTION:A steel-sheet transporting roll is provided with plural insulating rings 5, which are fitted with spaces apart on the outer circumference of a roll barrel, and rings 6 which are each fitted on the outer side of these insulating rings and made of a heat resisting alloy. In addition, the roll is provided with an insulating layer 5' covering the surface of the roll barrel and with the plural rings 6 which are fitted with spaces apart on the outer circumference of this insulating layer and made of a heat resisting alloy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating roll for conveying a steel sheet, and more particularly to an insulating roll for conveying a steel sheet excellent in spark resistance, which is arranged in the vicinity of an induction heating device provided in a rolling line for hot-rolled steel sheets. It's about rolls.

[0002]

2. Description of the Related Art High-pressure water is sprayed on a hot-rolled steel sheet after rough rolling to perform surface descaling. At this time, however, the edges of the steel sheet tend to be overcooled compared to the central portion. This causes a difference in deformation resistance, which hinders subsequent finishing rolling or hot straightening. Among thick steel plates, for example, long materials for shipbuilding or bridges and building materials such as steel frames,
Similarly, the edges are supercooled due to the effects of water cooling or accelerated cooling during controlled rolling, which not only hinders finish rolling, but also causes residual stress in the product, which may cause the stripping of thick steel plates. There is a problem in that the cutting material has a large slitting camber (horizontal bending).

[0003] Usually, as a solution to these problems, the supercooled region at the edge of the steel sheet is reheated by induction heating immediately before hot leveling after water cooling and / or during hot leveling, and the temperature difference between the central portion and the edge portion of the steel sheet is reheated. However, a method of making the temperature in the plate width direction uniform so that it is within 50 ° C., for example, is adopted (see Japanese Patent Laid-Open No. 4-66271).

FIG. 2 is a diagram showing a schematic structure of an apparatus for induction-heating an end portion of a steel sheet. The steel sheet 4 is used in a hot rolling line.
An induction heating coil 9 capable of rapid heating is used to heat the end of the
Is heated between. However, in order to convey the hot-rolled steel material or the thick steel plate, since a metal conveyance roll such as steel is used from the viewpoint of strength and durability, the induction heating coil 9 causes the secondary heating along with the induction heating of the end portion. Induced electromotive current is generated between the hot-rolled steel sheet and the transport roll.

FIG. 3 is a diagram showing a state of generation of an induced electromotive current due to induction heating. As shown in the figure, when induction heating is applied to an end of a hot-rolled steel sheet, it is generated from the induction heating coil 9. Most of the generated magnetic flux concentrates at the end of the steel sheet around the induction heating coil 9, but part of it spreads also to the periphery to generate the induced electromotive current 10. Induced electromotive current 10 is a steel plate transport roll 1
When it spreads to the upper steel plate 4, a part of the induced electromotive current 10 forms an induced electromotive current loop 11 between the steel plate and the steel plate conveying roll, as shown in FIG. Therefore, sparks are generated between the steel sheet and the rolls when the steel sheet and the rolls intermittently or momentarily come into contact with the rolls at the edges of the steel sheet when the steel sheet is conveyed.

FIG. 5 shows a plate width 25 explained in an embodiment described later.
It shows the situation of spark marks generated on the back surface of a hot rolled steel plate of 00 mm.
There are continuous spark marks on the 100 mm part. When such spark marks are generated, the value of the product is remarkably reduced. Therefore, suppressing the generation of sparks is an essential condition for induction heating the end of the hot rolled steel sheet.

As means for suppressing the occurrence of the above-mentioned sparks, an end heating device for a rolled material provided with a transporting roll (a roll shown in FIG. 6) for spraying an insulating layer of ceramics or the like on the surface, and both end portions of a rolled steel plate An end heating device for rolled material, which is provided with a stepped conveying roll (roll shown in FIG. 7) in which a portion through which a groove passes is proposed (Actual Kaihei 4-13
(See Japanese Patent No. 4203). That is, the insulating roll 1 shown in FIG.
By spraying the insulating layer 5 on the surface, the insulating property with respect to the rolled material is secured and the occurrence of sparks is suppressed. Further, in the stepped conveying roll 1 shown in FIG. 7, the step portions 7 are provided at both ends of the roll and are supported only within the range of the steel sheet supporting portion 8 of the roll. The contact with the transport roll 1 is avoided.

Although the above-mentioned end heating devices proposed so far exhibit the desired effect in suppressing the occurrence of sparks, when they are arranged in the rolling line, they have the following operational problems. is there.

A roll having an insulating layer sprayed on the surface shown in FIG. 6 has a short life. The shape of the hot-rolled steel sheet changes depending on the rolling conditions, but in particular, the shape of the tip of the steel sheet largely depends on the rolling conditions, and therefore the tip may often warp downward due to the factors of the rolling process. In this case, since the leading end of the steel sheet collides with the steel sheet conveying rolls one after another during conveyance, the insulating layer formed by the ceramic spraying on the roll surface is destroyed by the impact, and the life of the conveying roll is extremely shortened.

The stepped transport roll shown in FIG. 7 has no problem when the heating region is limited to a narrow range of the end portion of the steel plate, that is, when the range in which the induced electromotive current flows is limited to the end portion. When the area must be widened, that is, when the range of the induced electromotive force extends to the vicinity of the central portion of the plate width, the size of the steel plate supporting portion 8 shown in the drawing is limited, and it becomes difficult to convey the steel plate.

[0011]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned problems of the prior art and, even when the end portion of the hot-rolled steel sheet is induction-heated, it is provided between the hot-rolled steel sheet and the steel sheet conveying roll. The purpose of the present invention is to provide a roll for transporting a steel sheet that does not generate sparks and has a long roll life.

[0012]

The gist of the present invention is, as shown in FIG. 1, a steel sheet conveying roll of the following (1) or (2).

(1) It is characterized by having a plurality of insulating rings 5 fitted around the outer periphery of the roll barrel at intervals and a ring 6 made of a heat-resistant alloy fitted on the outer side of each of the insulating rings. Roll for transporting steel sheet (illustrated in FIG. 1A).

(2) Conveying steel sheet characterized by having an insulating layer 5'covering the surface of the roll barrel and a plurality of rings 6 made of a heat-resistant alloy fitted around the outer periphery of the insulating layer at intervals. Roll (illustrated in FIG. 1B).

[0015]

The contents of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a view showing an example of the structure of a steel plate transport roll of the present invention. FIG. 1 (a) shows an example of a roll in which an insulating ring and a ring made of heat-resistant alloy are fitted on the roll barrel surface. FIG. 3B is an axial longitudinal cross-sectional view showing (b) an axial longitudinal cross-section showing another example of a roll in which an insulating layer is formed on the surface of the roll barrel and a heat-resistant alloy ring is fitted on the roll barrel surface. It is a figure. Furthermore, (c) is (a) and (b)
FIG. 4 is a cross-sectional view taken along the line AA of FIG.

Usually, a roll used for conveying a steel sheet in a hot rolling line is a roll having a shape as shown in FIG. 10, and is largely divided into two parts due to its structure. That is, the steel plate transporting roll 1 is divided into a roll barrel portion 1b that supports and transports the steel sheet 4 and a roll neck portion 1n that is in contact with the bearing 3 at both ends of the roll.

As is clear from comparison between FIG. 1 and FIG. 10, the steel plate carrying roll of the present invention is (1) an insulating ring 5 fitted on the outer periphery of the roll barrel as compared with the conventional carrying roll. A heat-resistant alloy ring 6 fitted on the outside of each of the insulating rings, and (2) an insulating layer 5 ′ covering the surface of the roll barrel, and fitted on the outer periphery of the insulating layer. It is characterized by having a ring 6 made of a heat-resistant alloy.

The insulating ring 5 or the insulating layer 5'is provided between the roll barrel surface of the metal roll and the steel plate, because the insulating property of the transport roll is ensured as described above.
This is to prevent the occurrence of sparks. Further, in the present invention, it is preferable to form the insulating layer 2 on the roll neck portion that comes into contact with the roll bearing 3 by thermal spraying of, for example, ceramics. The insulating layer 2 is formed on the roll neck portion because it is preferable to prevent electrolytic corrosion of roll bearings such as bearings even when an induced electromotive force is generated in the steel plate transport roll itself due to spread of magnetic flux.

The insulating ring 5 or the insulating layer 5'is insulative,
It is formed of ceramics or the like having excellent heat resistance. Examples of ceramics include alumina, magnesia, beryllia, zirconia and the like. To suppress the occurrence of sparks, it is desirable that the insulation resistance be 1 kΩ or more.
In particular, it is more desirable that it is several kΩ or more. The thickness of the insulating ring 5 or the insulating layer 5 ′ may be set to have such an insulation resistance. For example, alumina has a thickness of 0.1 mm
The insulation resistance is 1.2 KΩ.

The heat-resistant alloy ring 6 may be attached to the roll barrel surface of a metal roll by shrink fitting or the like to be fixed to the roll, or may be structured so that it can be removed from the roll. However, even in this case, since it is necessary to fit the heat-resistant alloy rings 6 at intervals, the structure must be such that movement in the axial direction is restricted. Further, the material of the ring 6 is made of an alloy excellent in corrosion resistance, heat resistance, and wear resistance, for example, high chromium steel, stainless steel, etc., because it constantly comes into contact with high temperature hot rolled steel in a hot rolling line. .

The width of the heat-resistant alloy ring 6 is preferably narrow. This is because it becomes easy to suppress the loop 11 of the induced electromotive current generated between the steel plate transport roll and the steel plate shown in FIG. In order to effectively suppress the loop 11 of the induced electromotive current, the width of the heat-resistant alloy ring 6 is preferably 500 mm or less. In the relationship between the width of the heat-resistant alloy ring 6 and the width of the insulating ring 5, considering the strength or stability of the insulating ring 5, the width of the insulating ring 5 is about the same as the width of the heat-resistant alloy ring 6 or more. The width is preferably. The wall thickness of the heat-resistant alloy ring 6 is
Having appropriate rigidity, taking into consideration rolling conditions, steel plates for transportation, etc.
Set it to withstand the impact of steel sheet transportation.

Two examples of the structure of the steel sheet transport roll of the present invention are shown in FIG. 1. In the manufacturing process, an insulating layer is formed on the surface of the roll barrel as shown in FIG. It is easier to place a ring made of heat-resistant alloy on the roll barrel surface, but since the insulating layer is formed on the entire surface of the roll barrel, the cost is significantly different from that shown in FIG. There was no The spark resistance is almost the same in both cases.

[0024]

EXAMPLES The effects of the steel sheet conveying rolls of the present invention (invention examples a and b rolls of Table 1) were compared with those of comparative examples (Comparative examples a and b of Table 1).
A detailed description will be given while comparing with (roll).

FIG. 8 (a) is a view showing the shape and dimensions of the steel sheet conveying roll of the present invention, and FIG. 8 (b) is a cross section taken along the line AA of FIG. 8 (a). It is a figure.

FIG. 9 is a diagram showing the shape and dimensions of a conventional steel sheet conveying roll of a comparative example. In each of the present invention example and the comparative example, two rolls (total number of eight rolls) were manufactured, placed in front of and behind the induction heating coil, and sparks were generated when the end of the steel sheet was induction-heated under the following heating conditions. The situation was compared.

1. Steel plate transport roll (1) Example of the present invention (see Fig. 8 for dimensions) a Roll: 200 mm wide, 1 mm thick insulating ring and heat resistant steel (JIS SUH310) 200 mm wide, 24 mm thick outer ring
6 sets of rolls fitted on the surface of a 350 mm roll barrel (that is, rolls having the structure shown in FIG. 1A) b roll: thickness 1 on the entire surface of a roll barrel having an outer diameter of 348 mm
mm insulation layer and heat-resistant steel ring (material,
A roll in which 6 sets of the same size as the a roll are fitted on the roll barrel surface (that is, the roll having the structure shown in FIG. 1B). (2) Comparative example (see FIG. 9 for the size) a roll: roll barrel Roll with no insulating layer on the surface b Roll: Roll with a 1 mm thick alumina sprayed layer as an insulating layer on the surface of the roll barrel (3) Roll material All are made of heat resistant steel Material to be heated by induction heating 15 mm thick, 2500 mm wide, 10000 mm long carbon steel is used. Transport conditions Distance between transport rolls: 1000 mm, transport speed: 30 m / min 4. Heating condition The central temperature of the material to be heated before induction heating is about 500 ℃.
The temperature of the end of the heated material during transportation is 100
C was raised to 600 ° C at maximum.

The electric power input for induction heating was 5000 kW.

Under the above conditions, induction heating of the steel plate edge is performed,
The state of spark generation between the steel sheets of the present invention example and the comparative example was compared. Further, the strength and durability of each roll were also compared. The results are shown in Table 1.

[0030]

[Table 1]

As is clear from Table 1, the roll of Comparative Example a used as a conventional type roll can be visually confirmed to generate sparks near the edges of the steel sheet, and as shown in FIG. A mark was generated. On the other hand, inventive example a,
No spark was observed in the b roll and the comparative b roll. Further, in a comparative study of strength and durability, the roll of Comparative Example b had a crack on the surface of the sprayed layer due to the collision of the tip of the steel plate, but in the present invention example, the ring surface of the rolls a and b were not damaged, and the insulating layer was not damaged. There wasn't.

[0032]

By using the steel sheet transport roll of the present invention, it is possible to prevent the occurrence of sparks between the steel sheet and the steel sheet transport roll during induction heating. Moreover, the roll of the present invention has sufficient strength and durability, and has a long life.

[Brief description of drawings]

FIG. 1A is an axial longitudinal sectional view showing an example of a roll in which an insulating ring and a ring made of a heat-resistant alloy are fitted on a roll barrel surface, and FIG. 1B shows an insulating layer formed on the surface of the roll barrel. And (c) an axial longitudinal sectional view showing another example of a roll in which a ring made of a heat-resistant alloy is fitted on the roll barrel surface.
[Fig. 3] is a transverse cross-sectional view taken along the line A-A of Figs.

FIG. 2 is a diagram showing a schematic configuration of an apparatus for induction heating an end portion of a steel plate.

FIG. 3 is a diagram showing how an induced electromotive current is generated due to induction heating.

FIG. 4 is a diagram for explaining an induced electromotive current loop generated between a steel plate and a steel plate transport roll.

FIG. 5 is a diagram showing a situation of spark marks generated on the back surface of hot-rolled steel.

FIG. 6 is a longitudinal cross-sectional view in the axial direction of a steel plate transport roll having an insulating layer on the surface for the purpose of suppressing sparks during induction heating.

FIG. 7 is a longitudinal cross-sectional view in the axial direction of a stepped steel plate transport roll for the purpose of suppressing sparks during induction heating.

FIG. 8A is a diagram showing the shape and dimensions of a steel sheet conveying roll according to an embodiment of the present invention, and FIG. 8B is a diagram showing FIG. 8A.
It is the figure which showed the cross section of the AA arrow.

FIG. 9 is a diagram showing the shape and dimensions of a steel sheet transport roll of a comparative example.

[Fig. 10] Fig. 10 is a diagram showing the shape and structure of a roll that is usually used for conveying steel plates in a hot rolling line.

[Explanation of Codes] 1 ... Roll, 2 ... Insulating layer, 3 ... Roll bearing, 4 ... Steel plate,
5 ... Insulating ring 5 '... Insulating layer, 6 ... Heat-resistant alloy ring, 7 ... Step, 8 ...
Steel plate supporting portion 9 ... Induction heating coil, 10 ... Induced electromotive current 11 ... Induced electromotive current loop between steel sheet and steel sheet conveying roll

Claims (2)

[Claims] 1. A steel sheet carrier comprising: a plurality of insulating rings fitted around the outer periphery of a roll barrel at intervals; and a ring made of a heat-resistant alloy fitted on the outside of each insulating ring. For rolls. 2. An insulating layer covering the surface of the roll barrel,
A roll for carrying a steel sheet, comprising a plurality of heat-resistant alloy rings fitted around the outer periphery of the insulating layer at intervals.