JPH05195185A - Manufacture of coated roll - Google Patents

Abstract

PURPOSE:To manufacture a film having excellent stickness with a core metal by forming a thermal spraying film of only metal on the surface of the core metal in a roll and films increasing ceramic ratio in order from the surface. CONSTITUTION:On the surface of the roll 1 for guide in a rolling mill, as a first layer, the metal thermal spraying film 2 having 50% Ni and 50% Cr and as the second layer, the thermal spraying film 3 having 40% Ni, 40% Cr and 20% chromium carbide, as a third layer, the thermal spraying layer 4 having 30% Ni, 30% Cr and 40% chromium carbide, as a fourth layer, the thermal spraying layer 5 having 25% Ni, 25% Cr and 50% chromium carbide and as a fifth layer, the thermal spraying layer 6 having 20% Ni, 20% Cr and 60% chromium carbide are formed. The thickness of the all film layers is made to be 0.75mm. The roll by this method unnecessitates the heat treatment for a long time and the thermal spraying film having the composition according to the use and the using condition of the roll can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a coated roll whose surface is spray coated with a high-performance material.

[0002]

2. Description of the Related Art Methods of spray coating the surface of rolls include wire spraying, rod spraying, powder spraying, etc., depending on the form of the material used, and gas spraying, plasma spraying, etc., depending on the heat source for melting the melted material. Depending on the atmosphere, there are atmospheric spraying and vacuum spraying. Furthermore, there is also a thermal spray melting method in which the self-fluxing alloy is sprayed and then the coating is melted by heat treatment to be fused with the material. Thermal spray materials include metals, ceramics,
There are cermets and plastics.

For example, in the case of a roll in a continuous annealing furnace, if the surface is metal, foreign matter or iron oxide adheres to the surface,
Gradually, they grow and become projections, and they may be pushed into the surface of the thin plate and cause flaws. For this reason, a roll coated with a ceramic material that is hard to be adhered with foreign matter and iron oxide is used. However, in a roll obtained by spraying a ceramic material, the thermal expansion difference between the roll core metal and the coating is large, and therefore the thermal spray coating easily peels off due to thermal shock.

Therefore, a method is widely used in which a metal having good adhesion to a roll core is used to perform thick thermal spraying and heat treatment is performed for a long time so that the entire coating surface is made into ceramics.

[0005]

However, according to this method, the composition between the metal coating on the surface of the roll core and the ceramic coating on the coating cannot be freely changed depending on the application of the roll and the use conditions. In addition, it has a problem that it requires a heat treatment for a long time because it is a small-quantity production method, which requires a very long man-hour and a high manufacturing cost.

The present invention has been made in order to solve the problems of the conventional method for producing a coated roll, and by performing thermal spraying which changes the composition of the coating layer in the thickness direction, the application and use conditions of the roll. It is an object of the present invention to provide a method for producing a coated roll, which can form a sprayed coating according to the above, has excellent adhesion to the roll core metal, and does not require long-term heat treatment.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a coated roll for forming a thermal spray coating on the surface of a roll core metal
This is a method of manufacturing a coated roll in which a 100% metal sprayed coating is formed on the surface of a roll core metal, and the coating is successively formed on the surface of the coating by reducing the amount of metal and increasing the amount of ceramics.

[0008]

By forming a sprayed coating of 100% metal on the surface of the roll core, a metal coating having good adhesion to the roll core can be formed. By sequentially forming a thermal spray coating with reduced metal and increased ceramics on the surface of this coating, the boundary with the coating of 100% metal of the first layer is eliminated, and the thermal spray coating that integrates the entire thermal spray coating Can be formed. By forming a thermal spray coating according to the purpose on the outermost surface, a thermal spray coating layer having a composition that is sequentially changed from the metal layer to the ceramic layer can be obtained.

According to this method, the adhesion between the roll core metal and the coating is improved and the heat conduction to the coating layer is improved, so that the coating is not peeled off from the roll core due to the difference in thermal expansion. Further, since the outermost surface is a sprayed coating suitable for the purpose, foreign matter and iron oxide will not adhere.

[0010]

EXAMPLES Examples will be described below. Example 1 In Example 1, a thermal spray coating of 100% metallic aluminum (Al) was formed on the surface of the roll core metal in an inert gas atmosphere, and the metallic aluminum was continuously reduced on the surface of the coating to form alumina ( Al
₂ O ₃ ) -increased thermal spray coating is formed in sequence, and a thermal spray coating of 100% alumina is formed on the outermost surface. The thickness of the coating layer is 10 mm. FIG. 1 shows the composition change in the thickness direction of the coating layer.

In FIG. 1, the horizontal axis shows the compositional change in the thickness direction of the coating layer, and the vertical axis shows the distance from the surface of the roll core metal. As is clear from the figure, the composition of the coating layer has a continuous (microscopically stepwise) gradient change, and there is no sudden change in the physical properties. Moreover, since the composition of the coating layer changes at a constant ratio, the coating layer was of extremely high quality, and the desired coated roll was obtained.

Example 2 In Example 2, in the inert gas atmosphere, the first layer of Ni: Ni was used as the first layer on the surface of the guide vertical roll of the rolling mill having a diameter of 80 mm and a length of 700 mm.
50% -Cr: 50% metal spray coating on the second layer Ni: 40% -Cr:
40% -Chromium carbide 20% sprayed coating on the third layer Ni: 30
% -Cr: 30%-Chromium carbide 40% sprayed coating on the 4th layer
Ni: 25% -Cr: 25%-5% spray coating of chromium carbide
A thermal sprayed coating of Ni: 20% -Cr: 20% -Chromium carbide 60% was formed on the first layer, and the total thickness of the coating layer is 0.75 mm. FIG. 2 schematically shows the compositional change in the thickness direction of the coating layer, and FIG. 3 schematically shows the cross section of the roll having the sprayed coating formed thereon.

In FIG. 2, the horizontal axis indicates the coating layer and the vertical axis indicates the inside of the coating layer.
The amounts of Ni, Cr and chromium carbides are shown. As is clear from the figure, the composition of the coating layer changes stepwise, but the composition of each coating layer is the same as the composition blended in the thermal spraying process. As shown in FIG. 3, the coating layer is formed on the surface of the roll core metal 1 as follows: 1 layer 2, 2 layer 3, 3 layer 4, 4
Uniform sprayed coatings of layers 5 and 6 are formed.

As described above, according to the method of the present invention, it is possible to change the composition of the film in a gradient change or a stepwise change according to the purpose, and it is possible to produce a coating roll suitable for the application and use conditions. ..

[0015]

INDUSTRIAL APPLICABILITY The present invention forms a 100% metal sprayed coating on the surface of a roll cored bar in the production of a coated roll for forming a sprayed coating on the surface of a roll cored bar, and reduces the metal on the surface of this coating. A method for producing a coated roll for sequentially forming a thermal spray coating with increased ceramics, and according to the method of the present invention, a composition according to the application and use conditions of the roll can be obtained without performing heat treatment for a long time. It is possible to form a thermal sprayed coating having the same, and it is possible to produce a coated roll having a coating having excellent adhesion to the roll core metal.

[Brief description of drawings]

FIG. 1 is a diagram showing a composition change in a thickness direction of a thermal spray coating layer of Example 1.

FIG. 2 is a diagram showing a composition change in a thickness direction of a thermal spray coating layer of Example 2.

FIG. 3 is a view schematically showing a cross section of a roll on which a thermal spray coating of Example 2 is formed.

[Explanation of symbols]

1 ... Roll core metal, 2 ... 1 layer, 3 ... 2 layers, 4 ... 3 layers, 5 ...
4 layers, 6 ... 5 layers.

Claims (1)

[Claims] 1. In the production of a coated roll for forming a sprayed coating on the surface of a roll core metal, a metal 1
A method for producing a coated roll, which comprises forming a thermal sprayed coating of 00%, reducing the amount of metal on the surface of the thermal sprayed coating, and successively forming a thermal sprayed coating having increased ceramics.