JPH06128652A - Thermal crown prevention roll - Google Patents

Abstract

(57) [Abstract] [Purpose] Prevents non-uniform temperature distribution from occurring on the surface of rolls used for cold rolled steel sheet transport rolls, cooling rolls, energizing rolls, pressing rolls, etc. . [Structure] A roll shell 2 having a high thermal conductivity on a roll shaft 1.
To fit. The roll shaft 1 and the roll shell 2 are contacted and fixed only at both ends. In the central portion, a space 3 or a heat insulating layer is provided between the roll shaft 1 and the roll shell 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal crown preventing roll used as a roll for cold-rolled steel sheets, a cooling roll, an energizing roll, a pressing roll, and the like.

[0002]

2. Description of the Related Art In a cold-rolled steel sheet conveying roll or the like, only the surface of the central portion of the roll becomes hot when it comes into contact with a high-temperature conveyed product. For example, in the cooling zone of the heat treatment furnace for cold-rolled steel sheets, the hot steel sheet comes into contact with the transport roll cooled by the atmosphere, and only the roll surface of the portion that comes into contact with the steel sheet has a high temperature, and the portion that does not come into contact with the steel sheet has a low temperature. It remains.
In this state, when switching the threading from the narrow material to the wide material, the central part of the wide material comes into contact with the high temperature part of the roll, but the end part comes into contact with the low temperature part of the roll. At the beginning of plate switching, there is a problem that only the edges of the steel plate are rapidly cooled and a heat buckle (longitudinal wrinkle narrowing) occurs.

Further, when only the surface of the central portion of the roll has a high temperature in this way, a phenomenon called thermal crown occurs in which only the central portion of the roll having a high temperature expands. Then, especially when switching to a wide material, the contact between the steel plate and the roll becomes insufficient,
For example, when used as an energizing roll or its pressing roll, sparks are generated between the energizing roll and the steel plate, and the steel plate surface and the energizing roll surface both have melt damage flaws.
There is a problem that product quality is deteriorated.

As described above, when the surface temperature of the roll becomes nonuniform, it causes various problems. Therefore, in order to make the roll surface temperature uniform, JP-A-57-136793 is used.
The publication describes forming a conductive magnetic film on the surface of the roll so that the resistance value of the portion where the magnetic flux density becomes high becomes large. It is said that a uniform temperature distribution can be obtained when the roll is induction heated. Further, Japanese Patent Application Laid-Open No. 61-79733 describes a transport roll in which the surface of a roll body is made of conductive ceramics so that it can be electrically heated. It is said that this roll can make the temperature distribution in the width direction of the roll uniform by conducting electricity to the conductive ceramics and resistance heating.

[0005]

However, these conventional techniques are not sufficient as means for preventing the roll surface temperature from becoming non-uniform and causing a thermal crown. First, these require electricity for heating the rolls, and the equipment therefor must be complicated and expensive. Further, even if the temperature of the roll surface is uniform, if the roll comes into contact with a substance having a temperature different from the temperature of the roll surface, the temperature distribution on the roll surface becomes non-uniform, and the temperature distribution inside the roll also becomes non-uniform due to this. Therefore, the generation of thermal crown cannot be completely prevented.

It is an object of the present invention to provide a thermal crown preventing roll which does not cause a non-uniform temperature distribution on the roll surface and therefore can prevent the generation of thermal crown.

[0007]

The gist of the present invention is to fit a roll shell having a high heat conductivity onto a roll shaft so that the roll shaft and the roll shell are contacted and fixed only at both ends, and the roll shaft is provided at the central part. A heat crown prevention roll characterized in that a gap or a heat insulating layer is provided between the roll shell and the roll shell.

[0008]

In the present invention, in order to prevent the roll from coming into contact with a conveyed product such as a steel plate and partially becoming high temperature to generate a thermal crown, as shown in FIG. 1, the roll having high thermal conductivity is used. The shell 2 is fitted onto the roll shaft 1 via the void 3 or the heat insulating layer. The width of the void 3 or the heat insulating layer is made wider than the range of passage of the conveyed product 6 such as a metal band. With such a configuration, when a part of the roll shell 2 comes into contact with the conveyed product 6 and reaches a high temperature, the roll shell 2 is made of a material having high thermal conductivity, so that heat is transferred to other parts. However, a gap 3 is formed between the roll shell 2 and the roll shaft 1.
Alternatively, since the heat insulating layer is present, the heat flux does not go to the roll axis center direction but to the roll width direction. As a result, the temperature of the surface of the roll shell 2 is made uniform in the width direction, and it is possible to prevent the generation of a heat buckle and the generation of a heat crown on the roll shell 2 when switching to a wide material. Further, also with respect to the roll shaft 1, heat is transferred only through the contact portions 4 with the roll shells 2 at both ends, so that it is possible to prevent only a part of the roll shaft 1 from reaching a high temperature, and in the end, the roll shaft 1 It is also possible to prevent a heat crown from being generated. On the contrary, even when the cooling water is passed through the roll shaft 1 for cooling, it is possible to prevent the temperature of the roll shell 2 in the range through which the conveyed product 6 passes from being lowered too much due to the voids 3 or the heat insulating layer.

The roll for preventing thermal crown of the present invention not only prevents the generation of thermal crown by making the temperature distribution on the roll uniform as described above, but also applies a reduction by sandwiching the metal strip with another roll. In case, roll shell 2
It is also possible to apply a uniform reduction by bending.
That is, a gap 3 is formed between the roll shaft 1 and the roll shell 2.
Therefore, even if the metal strip has a defective shape or the other roll has a thermal crown, the roll shell 2 may bend and absorb the fluctuation as shown by the broken line in FIG. As a result, it is possible to reduce the pressure uniformly at all times. This is the same even if a heat insulating layer is used instead of the voids 3 as long as it is a soft heat insulating layer such as a ceramic fiber.

As the material of the roll shell, a substance having a high thermal conductivity, specifically graphite or copper, can be adopted. In order to prevent abrasion or the like, surface hardening treatment such as forming a thermal spray coating 8 of high carbon steel on the surface of the roll shell 2 as shown in FIG. 2 may be performed. The material of the roll shaft is not particularly limited, and for example, structural carbon steel of S45C or S35C can be adopted. Further, as the heat insulating layer, one filled with mortar or ceramic fiber can be adopted.

[0011]

Example A thermal crown preventing roll as shown in FIG. 3 was manufactured by using extruded graphite as the material of the roll shell and S35C structural steel as the material of the roll shaft. That is, shaft length 200
0 mm, shaft diameter 160 mm, roll shaft 1, shell shell length 10
The roll shell 2 having a thickness of 00 mm and a shell thickness of 20 mm was externally fitted, and at this time, 300 mm from the center of the roll shaft 1 to the left and right.
The area (total 600 mm) was shaved by about 5 mm, and ceramic fibers were packed to form the heat insulating layer 7. The surface of the roll shell 2 is made of high carbon steel (0.8%
The thermal spray coating 8 of C) was formed to 100 μm.

Using this heat crown prevention roll as an energizing roll, a plain steel plate having a plate width of 200 mm and a plate thickness of 0.5 mm is passed through 6 to 60 mpm while being energized and heated up to 750 ° C. As a result, a maximum of 7500 A is energized. No sparks were generated and stable electric heating was possible.

On the other hand, when the roll shell 2 is fitted to the roll shaft 1 without providing a heat insulating layer or a gap between the roll shaft 1 and the roll shaft 1, the roll is an electric current roll. The roll shaft expands to generate a thermal crown, and sparks are generated between the surface of the roll and the steel sheet at the time of heating by energization for about 10 minutes. This is because a thermal crown is generated on the roll shell and the shaft, resulting in poor contact between the roll surface and the steel sheet.

[0014]

According to the present invention, the temperature distribution on the roll surface can be made uniform without using a special heating device, and the heat buckle can be prevented.
Further, since the thermal crown that occurs due to the non-uniform temperature distribution can be prevented, the contact between the roll and the conveyed product can be favorably maintained, and the occurrence of sparks on the energizing roll can also be prevented.
Further, since the fluctuation can be absorbed by the deflection of the roll shell, it is possible to carry out uniform rolling at all times.

[Brief description of drawings]

FIG. 1 is a partially enlarged cross-sectional view of a thermal crown prevention roll of the present invention.

FIG. 2 is a diagram showing an example of a thermal crown prevention roll of the present invention.

FIG. 3 is a diagram showing another example of the thermal crown prevention roll of the present invention.

[Explanation of symbols]

 1 Roll Axis 2 Roll Shell 3 Void 4 Contact Part 5 Fixing Ring 6 Transported Material 7 Thermal Insulation Layer 8 Thermal Spray Coating

Claims (1)

[Claims] 1. A roll shell having a high thermal conductivity is externally fitted to the roll shaft, and the roll shaft and the roll shell are contacted and fixed only at both ends, and in the central part, a gap or heat insulation is provided between the roll shaft and the roll shell. A roll for preventing thermal crown, which is provided with a layer.