JP3004636B1 - Composite roll for hot rolling - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To be excellent in abrasion resistance and skin resistance as a material suitable for hot rolling, and to have a low coefficient of thermal expansion of a whole roll from the time of new roll to the time of disposal of the roll, thereby improving the sheet passing property. An object is to provide an excellent composite roll for hot rolling. SOLUTION: In a high-speed composite roll in which the inner layer is made of a steel material, the cross-sectional area ratio between the outer layer and the inner layer in the roll rejection diameter is set to 1/4 or more, whereby the composite roll from the new roll diameter to the rejection diameter is obtained. The total thermal expansion coefficient α is 1
It was suppressed to 2.0 × 10 ⁻⁶ / ° C. or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a composite roll for hot rolling. More specifically, the present invention relates to a composite roll for hot rolling which is suitable for use as a work roll of a hot finish rolling mill for a steel plate or the like and has excellent sheet passing properties.

[0002]

2. Description of the Related Art In order to cope with the trend toward lower cost and higher quality of hot rolled products, development and practical use of rolls with excellent wear resistance that allow for an increase in the amount of rolling per unit roll, that is, free of a rolling schedule. Is being promoted. These rolling rolls use an outer layer used for rolling to form MC, M having high hardness.
With _{6 C-type} carbides high-speed steel material is dispersed, conventional Ni- Glen based material, as compared to the high chromium-based material, in that with a very good wear resistance of 5 to 15 times Has features. Therefore, the rolling schedule can be greatly expanded such that the rolling amount per unit roll can be increased to five times or more that of the conventional rolling roll.

[0003] High-speed composite rolls in which the inner layer (shaft material) is made of a steel-based material are currently the most applied as work rolls for hot finishing rolling mills for steel sheets, and in terms of wear resistance and surface roughness. Demonstrating good results. On the other hand, there is a problem in the sheet passing property. Generally, in hot finish rolling of a steel sheet, as the rolling of a work roll progresses, the temperature at the center of the roll becomes higher than that at the end, and uneven thermal expansion occurs in the axial direction. If the thermal expansion exceeds the prediction, the steel sheet will elongate in the middle and a drawing accident will occur, and the shape of the steel sheet will be poor, or cracks will easily occur on the roll surface. These tendencies are more pronounced in the high-speed composite roll. It is considered that the reason for this is that the high-speed composite roll has a larger thermal expansion coefficient than the conventional Ni-grain-based material or the like.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-mentioned problems in a high-speed composite roll in which the inner layer is made of a steel-based material, and provides a material suitable for hot rolling, such as abrasion resistance and rough surface resistance. It is an object of the present invention to provide a composite roll for hot rolling that has excellent heat resistance, a low coefficient of thermal expansion of the entire roll from when the roll is new to when it is discarded, and has excellent sheet passing properties.

[0005]

As a result of repeated experiments and studies to solve the above-mentioned problems, the present inventor has found that the thermal expansion coefficient of the entire roll as a factor that deteriorates the sheet-passing property, Adjusting the relationship of the cross-sectional area ratio between the outer layer and the inner layer has been found to be a clue to a great solution, and the present invention has been completed.

That is, the composite roll for hot rolling of the present invention comprises:
Outer layer inner layer co When configured with high-speed steel material of steel-based material
A composite high-speed hot-rolling roll, comprising:
In the roll rejection diameter set as a guideline for
Outer layer made of the high-speed material and made of the steel material
The cross-sectional area ratio of the cross section perpendicular to the roll axis to the inner layer is 1
/ 4 or more, so that the thermal expansion coefficient
Has an inner layer made of a steel material exceeding 12.0 × 10 ⁻⁶ / ° C.
Even if the high-speed composite roll is formed, the new roll diameter
Heat of the entire composite roll from
The expansion coefficient α is kept to 12.0 × 10 ⁻⁶ / ° C or less.
Is a first feature. Further, the composite roll for hot rolling according to the present invention, in addition to the first feature, is characterized in that the outer layer and the inner layer in the roll rejection diameter are perpendicular to the roll axis.
A second feature is that the cross- sectional area ratio in the cross section is set to 1/4 or more and 1/1 or less. The third feature of the composite roll for hot rolling according to the present invention is that it is used as a work roll of a hot finish rolling mill for steel sheets, in addition to the first or second feature.

[0007] As the hot rolled composite roll is used,
As a result, the thickness of the outer layer gradually decreases,
In a section perpendicular to the roll axisThe cross-sectional area ratio decreases.
Due to the thermal expansion coefficient of the inner layer material,
The coefficient of thermal expansion of the entire unit gradually increases. Inner layer
For hot rolling with steel as the outer material and high-speed material as the outer layer
In the case of composite rolls, the inner layer steel is
Since the system material has a higher coefficient of thermal expansion,
As the cross-sectional area ratio between the outer and inner layers decreases,
The thermal expansion coefficient of the entire unit increases. And the whole roll
Thermal expansion coefficient α is 12.0 × 10^-6/ ℃Exceed
Then, the required sheet passing property of the roll is deteriorated.That is,
The thermal expansion coefficient α of the high-speed material constituting the outer layer is 12.0
× 10 ^-6 / ° C, the thermal expansion coefficient α of the inner layer
12.0 × 10 ^-6 Constructed of steel-based material exceeding / ℃
If the new material is used, the outer layer of high-speed
Because the area ratio is large, the thermal expansion coefficient α of the whole roll is
12.0 × 10 ^-6 / ° C or less,
When the thickness of the outer layer is reduced by use, high-speed materials
The cross-sectional area ratio of the material gradually decreases, and as a result,
The thermal expansion coefficient α of the entire tool is 12.0 × 10 ^-6 /
Exceeding ° C, leading to deterioration of the sheet passing property. So book
As a result of various experiments and studies, the inventor found that the inner layer was heated.
Expansion coefficient α is 12.0 × 10 ^-6 Steel exceeding / ℃
And the outer layer has a thermal expansion coefficient α of 12.0.
× 10 ^-6 Made of high-speed material with temperature less than / ° CHot
Rolling composite rolls
In the period leading up to the time of disposal, especially approaching disposal
In timeAlsoIn order to prevent the deterioration of plate properties,Compound row
The outer layer made of high-speed steel and the steel-based material
With the inner layerThe design of the cross-sectional area ratio should be
Considering each coefficient of thermal expansion of base materialUpso,Especially rolls
Roll rejection diameter set as a guideline for rejection
By providing a certain limit to the cross-sectional area ratio of
Get the idea that it is possible to prevent deterioration
It was reached.Usually, the work roll of the hot finishing mill
The outer diameter is 600 mmφ or more, but the rolling diameter is
It is about 100 mmφ. And according to conventional thinking,
When the rolls are discarded, the outer layer should be left around 10 mm on one side.
Rolls are manufactured in total. Such a conventionalBy way of thinking
IsBetween the outer and inner layersIn a section perpendicular to the roll axiscross section
The product ratio is about 1 / 2.5 for the new diameter and 1/10 or less for the rejected diameter.
WhenBecome. Therefore, the thermal expansion coefficient α is 12.0 × 10 ^-6 / ℃
If a steel-based material that exceeds
Even for rolls with high-speed materials as outer layers,Roll of
As use progresses, the thermal expansion of the entire roll will be greater than that of the outer layer.
Is also largely controlled by the amount of thermal expansion of the inner layer having a large thermal expansion coefficient.
Before the disposal, the thermal expansion coefficient α of the entire roll
12.0 × 10^-6/ ° C is exceeded, resulting in better sheet passing
It was causing problems.

According to the first aspect of the present invention, the outer layer is
It is made of high-speed steel and the inner layer is made of steel.
High-speed hot rolled composite rolls
The above-mentioned c in the roll rejection diameter set as a guide
An outer layer made of a chair material and an inner layer made of the steel material
The cross-sectional area ratio in the cross section perpendicular to the roll axis is 1/4 or more
By configuring so as to be above, the coefficient of thermal expansion is 1
The inner layer is composed of a steel material exceeding 2.0 × 10 ⁻⁶ / ° C.
High-speed composite rolls,
Until the waste diameter is reached, the thermal expansion of the entire composite roll
The tension coefficient α to 12.0 × 10 ⁻⁶ / ° C. or less.
This allows rolls to be rolled from new to discarded
During the entire period, there was a problem with the hot rollability
Heat resistant to wear and rough skin without squeezing
It became possible to perform cold rolling. According to the second aspect of the present invention, in addition to the above-mentioned action of the first aspect, the outer layer and the inner layer in the roll rejection diameter are perpendicular to the roll axis.
By setting the cross- sectional area ratio in the cross-section to 1/4 or more and 1/1 or less, without impairing the mechanical function and other functions as members of the rolling mill that the outer layer and the inner layer of this type of composite roll have respectively. As a composite roll for hot rolling, it is possible to ensure the threading property, the wear resistance, and the skin resistance throughout the entire use period. That is, the cross- sectional area ratio of the outer layer and the inner layer in the section perpendicular to the roll axis in the roll rejection diameter is 1/4.
If it is less than this, the threadability cannot be ensured. Also, the cross-sectional area ratio between the outer layer and the inner layer in the roll disposal diameter exceeds 1/1.
In such a case, the diameter of the inner layer also serving as the shaft becomes insufficient in strength, or the thickness of the outer layer at the time of disposal is large, which is uneconomical. According to the third aspect of the present invention, in addition to the above-described action of the first or second aspect,
By using the hot-rolling composite roll of the present invention as a work roll of a hot-rolling mill for a steel sheet, it is possible to satisfactorily perform hot-rolling of the steel sheet throughout the entire period from the time of new work to the time of disposal as a work roll. Can be.

[0009]

EXAMPLES Table 1 shows the change in the cross-sectional area ratio between the outer layer and the inner layer, the measured value of the thermal expansion when the temperature was raised to 100 ° C., and the change in the coefficient of thermal expansion in the example of the composite roll for hot rolling of the present invention. Shown in In Table 1, samples 1 and 2 are composite rolls of the present invention, and samples 3 to 5 are conventional composite rolls. Sample 5 is a composite roll made of a conventional Ni-grain-based material. In the composite roll for hot rolling of the present invention, the cross- sectional area ratio of the outer layer and the inner layer in the cross section perpendicular to the roll axis in the roll rejection diameter is 1/4 or more. On the other hand, in the conventional composite roll, the cross-sectional area ratio between the outer layer and the inner layer in the roll rejection diameter is 1/10 or less.

[0010]

[Table 1]

As is apparent from Table 1, as the roll diameter of the composite roll decreases (the thickness of the outer layer decreases), the thermal expansion coefficient of the entire composite roll increases due to the thermal expansion coefficient of the inner layer. . In Samples 1 and 2, which are examples of the present invention, the cross- sectional area ratios of the outer layer and the inner layer in the section perpendicular to the roll axis at the roll rejection diameter are 1 / 3.91 and 1 / 3.61, respectively. The cross-sectional area ratio is 1 /
4 or more, the thermal expansion coefficient α of the entire composite roll is 11.6 × 10
⁻⁶ / ° C., 11.6 × 10 ⁻⁶ / ° C., 12.0 ×
It turns out that it is less than 10 ^-6 / ° C. On the other hand, in the case of Samples 3 and 4, which are the conventional examples, the cross- sectional area ratios of the outer layer and the inner layer in the section perpendicular to the roll axis at the roll rejection diameter are 1 / 15.50 and 1 / 18.09, respectively. , It has changed greatly compared to when it is new, and the cross-sectional area ratio is 1
/ 4 or less. Therefore, the thermal expansion coefficient α of the entire composite roll is 12.6 × 1 at the time of roll disposal.
0 ⁻⁶ / ° C., 12.7 × 10 ⁻⁶ / ° C., and 12.0
× exceeds ^{10 -6} / ° C.. If the coefficient of thermal expansion α of the entire composite roll exceeds 12.0 × 10 ⁻⁶ / ° C., it is not possible to prevent the deterioration of the threadability in roll rolling.

[0012]

According to the composite roll for hot rolling according to the first aspect of the present invention, there is provided the present invention having the above-mentioned constitution, operation and effect.
The outer layer is made of a high-speed material and the inner layer is made of a steel material.
A composite high-speed hot-rolling roll, comprising:
In the roll rejection diameter set as a guideline for
Outer layer made of the high-speed material and made of the steel material
The cross-sectional area ratio to the inner layer is set to 1/4 or more.
As a result, the coefficient of thermal expansion exceeds 12.0 × 10 ⁻⁶ / ° C.
A high-speed composite roll with an inner layer made of
Even between the new roll diameter and the discarded diameter.
The coefficient of thermal expansion α of the entire composite roll to 12.0 × 10 ⁻⁶
/ ° C or less, this kind of high
The hot rolled composite rolls for hot rolling can be used throughout the entire period from the new rolls to the disposal of the rolls, without causing problems in the hot rollability of the hot rolled rolls , and also for abrasion resistance and skin resistance. It can be excellent. Also it is possible to achieve a significant improvement in the material roll unit. According to the composite roll for hot rolling according to the second aspect, in addition to the effect of the configuration according to the first aspect, the outer layer and the inner layer in the roll rejection diameter have a cross section perpendicular to the roll axis. The cross-sectional area ratio is 1 /
Since it is 4 or more and 1/1 or less, it does not impair the mechanical function and other functions as members of the rolling mill which the outer layer and the inner layer of this kind of composite roll have respectively, and as a composite roll for hot rolling. In addition, it is possible to ensure the sheet passing property, the wear resistance, and the skin roughness resistance throughout the entire use period. Further, according to the composite roll for hot rolling according to claim 3,
In addition to the effects of the configuration according to claim 1 or 2,
Since the work roll is used as a work roll of a hot finish rolling mill for a steel sheet, the work roll has excellent plateability throughout the entire period from the time of a new product to the time of disposal, and a significant improvement in roll basic unit can be achieved.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-268807 (JP, A) JP-A-9-29313 (JP, A) JP-A-10-192916 (JP, A) JP-A-5-1993 212558 (JP, A) JP-A-9-239411 (JP, A) JP-A-63-157707 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21B 27/02 B21B 27 / 00 B21B 28/00

Claims (3)

(57) [Claims] (1) The outer layer is made of a high-speed material and the inner layer is made of
Composite row for high-speed hot rolling of high-speed steel composed of steel-based material
Rolls that are set as a guideline for roll disposal
The outer layer made of the high-speed steel material and the steel at the disposal diameter
In the section perpendicular to the roll axis with the inner layer made of the base material
So that the cross-sectional area ratio becomes 1/4 or more.
Steel having a coefficient of thermal expansion exceeding 12.0 × 10 ⁻⁶ / ° C.
A high speed composite roll with an inner layer made of material
Also occur between the new roll diameter and the retired roll diameter.
The coefficient of thermal expansion α of the entire roll is 12.0 × 10 ⁻⁶ / ° C.
A composite roll for hot rolling, characterized in that the roll can be suppressed to the following . Wherein the outer layer and the inner layer in the roll waste 却径,
The cross- sectional area ratio in the cross section perpendicular to the roll axis is 1/4 or more and 1
The composite roll for hot rolling according to claim 1, wherein the ratio is not more than / 1. 3. The composite roll for hot rolling according to claim 1, wherein the composite roll is used as a work roll of a hot finishing mill for a steel sheet.