JP5057416B2 - Annealing sleeve roll - Google Patents

Description

  The present invention relates to a carbon roll mainly used in a sheet annealing line.

  The hearth roll in the furnace used in metal annealing, for example, continuous annealing of cold-rolled steel sheet, has a low temperature in the center of the roll when the steel sheet in contact with the furnace has a high ambient temperature and lower than the ambient temperature. The temperature becomes higher and the temperature distribution is in the roll axis direction. Depending on this temperature distribution, the roll profile produces a concave roll crown with a dent at the center and a high edge due to thermal expansion. Conversely, when it comes into contact with a steel plate having a temperature higher than the atmospheric temperature of the furnace, a convex roll crown is produced. In such a state, the steel plate is likely to have a temperature distribution, the shape is deteriorated and an ear wave or the like is easily generated, or the steel plate is meandered.

  Therefore, in order to suppress the temperature distribution in the roll due to contact with the metal material and the atmospheric temperature, and to make the roll that does not expand even if the temperature distribution occurs, consider the material of the roll body, Carbon is an example of a material that easily diffuses and does not thermally expand, that is, a material having both the properties of good thermal conductivity and resistance to thermal expansion. Carbon usually exhibits a thermal conductivity 2 to 3 times that of iron. In addition, the coefficient of linear expansion, which is an index indicating the amount of thermal deformation, is 1/2 to 1/10 that of iron. Even if a temperature distribution is present, the amount of thermal expansion is small, and the roll profile has an advantage that it does not easily change. . In this way, while carbon has the property of being strong against thermal crowns, it is softer and less strong than iron. Therefore, rolls used for transporting steel sheets, such as hearth rolls, are subject to large loads, and carbon It is difficult to use it alone as a structural material. Therefore, a sleeve roll is generally used in which a steel roll shaft is formed into a sleeve shape, and a carbon material is fitted to the roll body length, and this is generally called a carbon roll.

  Since the hearth roll is exposed to a high temperature of 700 to 1100 ° C. for a long time, the whole roll may be greatly deformed. As a roll cooling method, as disclosed in Patent Document 1 and Patent Document 2, a sleeve is used. An annular or spiral groove is provided on the inner surface of the roller or on the outer surface side of the roll shaft so that the cooling water can pass therethrough.

However, there is a problem of carburization as a deformation problem peculiar to the carbon roll.
This is because carbon material is used for the sleeve part and steel material is used as the shaft material, and the steel roll shaft that is the shaft material is always in contact with the carbon material that is the sleeve. When exposed to high temperatures for a long time, carburization occurs on the steel roll shaft. Since the temperature distribution is not uniform in both the circumferential direction and the roll axis direction of the hearth roll, carburization occurs unevenly, and the carburized portion expands in volume, so there is a volume difference depending on the position on the surface part of the steel roll shaft. Arise. Thereby, distortion arises in the trunk length part of a roll axis. When the roll shaft is deformed by this distortion and exceeds the allowable deformation amount of the carbon material constituting the sleeve, the sleeve is cracked.

Japanese Patent Publication No. 56-41321 JP 60-30562 A

Therefore, in general, the roll shaft is made of a heat resistant steel that is relatively difficult to carburize and that is made of a large amount of Ni or Cr. Even if it is used as, since it is continuously in contact with the carbon material for a long time in a high temperature atmosphere of 1000 ° C. or more, carburization gradually proceeds, and the roll shaft material is bent in about 6 months to 1 year. there is a problem that can not be used as Hasuro Lumpur.

  The present invention reduces the stress caused by volume expansion due to carburization generated on the surface by grooving the outer surface of the body portion of the roll shaft material that solves the above problems, and the amount of bending deformation in the roll axis direction The technology to greatly reduce

The present invention is an annealing sleeve roll covered with a carbon sleeve, at least one end of which is fixed to a roll shaft on the outer periphery of a steel roll shaft. A plurality of annular grooves are provided over the entire length of the carbon sleeve mounting range .

Since the carbon roll of the present invention is provided with grooves on the outer surface of the body portion of the roll shaft material, the stress generated by the volume expansion due to carburization generated on the surface is relieved, and the amount of bending deformation in the roll axis direction is greatly increased. It has become possible to reduce it.

  An embodiment of the present invention will be described with reference to FIGS.

The inventors have investigated and studied various phenomena in which the shaft material of the carbon roll is deformed in the axial direction due to the use at a high temperature for a long time, and the deformation is caused by the carbon from the carbon sleeve to the roll shaft material made of heat resistant steel . As a result of the carburization of the roll shaft, the roll shaft material expands and deforms unevenly, and the stress generated thereby exceeds the yield stress of the roll shaft material, resulting in deformation of the roll shaft. The present invention has been made by knowing that it leads to the above.

In the process of completing the invention, a commercially available surface treatment material such as a carburizing prevention material was applied to the outer surface of the body part of the roll shaft. The effect was thin. Moreover, although it is effective to apply Ni plating to the surface of the roll shaft, the roll manufacturing cost is increased, which is not practical.
FIG. 1 is a diagram showing the overall shape of the carbon roll of the present invention. The roll shaft is made of heat-resistant steel containing Ni and Cr, and is heat-treated by casting or forging. The body part to be fitted with the carbon sleeve is mirror-finished by sand finishing after cutting so as not to damage the soft carbon. Furthermore, a plurality of annular grooves for stress relaxation according to the present invention are machined on the outer surface of the roll shaft body at required intervals. The carbon material has a sleeve shape so as to cover the roll trunk length of the roll shaft material, and is fitted to the roll shaft. The sleeve is fixed to the roll shaft by a fixed key for preventing rotation. The fixed key is fixed to both ends or one end of the roll shaft body depending on the size of the roll. The material of the carbon sleeve may be an ordinary carbon material, and may be a material in which WC, TiC, TiN, or ceramic is added to improve wear resistance and conductivity.

  FIG. 2 is a view showing the external shape of a roll shaft member to which a carbon sleeve is attached. The roll total length is 2500 mm, the roll body total length is 1800 mm, and the carbon sleeve mounting range is 1500 mm. A carbon sleeve is attached to the roll body in the range indicated by the arrow. In this range, the annular groove is processed on the outer peripheral surface of the roll shaft at a pitch of 50 mm. FIG. 3 is an enlarged view of part A in the figure. FIG. 3 shows the detailed dimensions of the annular groove.

  The annular groove has a groove depth of 3 mm and a width of 1.0 mm, and the groove tip portion is R0.5 mm in order to relieve stress concentration. The grooves are provided over the entire length of 1500 mm, which is the carbon sleeve mounting range, at a pitch of 50 mm.

Next, the result of using this invention roll for the hearth roll of a thin-plate annealing line is shown in FIG. FIG. 4 shows the relationship between the number of months the roll is used and the amount of eccentricity of the roll shaft when the groove is formed on the shaft body of the carbon roll (the roll of the present invention) and when the groove is not formed (comparative example).
In the present invention, since the annular groove is provided on the outer surface of the body portion of the shaft member of the carbon roll, bending deformation due to carburization is greatly suppressed. As a result, the breakage of the carbon rolls was reduced, and the carbon roll replacement period, which was previously 6 months to 1 year, can be used for 2 years or longer.

  Since the life of the carbon roll is greatly extended, the present invention can be applied to various uses of transport rolls used in a high temperature environment.

It is drawing which shows the external appearance shape of a carbon roll. It is drawing which shows the roll axis | shaft structure of a carbon roll. It is drawing which expanded the A section of FIG. 2 explaining groove | channel shape. It is drawing which shows the relationship between the usage month of a carbon roll, and the eccentric amount of a roll axis | shaft.

Explanation of symbols

1 Carbon roll shaft material 2 Carbon sleeve fixing key 3 Carbon sleeve

Claims (1)

An annealing sleeve roll covered with a carbon sleeve, at least one end fixed to the roll shaft on the outer periphery of a steel roll shaft, and an annular groove for stress relaxation on the outer surface of the roll shaft body An annealing sleeve roll characterized in that a plurality of carbon steel sleeves are provided over the entire length of the carbon sleeve mounting range.

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