JPH05228601A - Manufacture of skin roll in galvannealing equipment - Google Patents

Abstract

PURPOSE:To obtain a roll which is difficult to peal off a carbide film by forming the carbide film having large resistance the erosion and wear on the outer surface of a sink roll used to galvannealing equipment. CONSTITUTION:Carbide particles of WC or MoC having 50-200mum average particle diameter are charged into a centrifugal casting die 1 together with molten metal having sp. gr. smaller than the sp. gr. of the carbide particles and solidified while concentrating the carbide particles having large sp. gr. on the outer peripheral surface of the molten metal by centrifugal force action, and distributed in an interval chill condition while concentrating the carbide particles on the outer peripheral surface.

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 sink roll in a hot dip galvanizing facility, and more specifically to a method for producing a sink roll using a centrifugal casting method.

[0002]

2. Description of the Related Art A sink roll used in a hot-dip galvanizing line is subject to a corrosive action due to molten zinc and a frictional action due to contact with a steel sheet to be plated. Conventionally, high Cr-high Ni alloys, 13% Cr stainless steel, etc. have been used as materials for this roll, but the corrosion resistance to molten zinc and the wear resistance to the steel sheet to be plated are insufficient, and it takes about 2 weeks. Had to be replaced by the use of.
In order to prevent corrosion and abrasion and to improve the life, a coating mainly composed of carbide such as WC is formed on the surface of a conventional high Cr-high Ni steel alloy or 13% Cr stainless steel roll by spraying. A two-layer sink roll has been proposed. This sink roll has very good corrosion resistance to molten zinc, but the adhesion state of the carbide coating is not sufficient. For this reason, there is a problem that the coating film is peeled off after about 2 months of use due to the surface pressure effect of the steel sheet to be plated during the operation, and the carbide coating film had to be re-sprayed.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a sink roll having an improved adhesion state of a carbide coating in order to prevent the carbide coating from peeling off after a short period of use.

[0004]

In order to achieve the above object, the present invention provides a molten metal having an average particle size of 50 to 200 μm and a WC or MoC carbide particle having a specific gravity smaller than that of the carbide particle. At the same time, it is put into a centrifugal casting mold to solidify carbide powder having a large specific gravity while being concentrated on the outer peripheral surface of the molten metal by the action of centrifugal force, and the carbide particles are concentrated and distributed on the outer peripheral surface in a cast-molded state.

The lower limit of the average particle size is 50 μm, because if it is smaller than that, it will dissolve in the metal melt during centrifugal molding, and it will not be possible to distribute the carbide particles to the outer peripheral surface in a cast-molded state. is there. Also, 20
The upper limit of 0 μm is that if it is larger than that, cracking tends to occur after molding. The reason why the carbide distributed on the outer peripheral surface is WC or MoC is that these carbides have a specific gravity at least larger than that of Fe, have excellent corrosion resistance to molten zinc, and have good wear resistance.

[0006]

FUNCTION The particles of WC or MoC are concentrated on the outer peripheral surface of the molten metal because they have a higher specific gravity than the inner layer material of the sink roll. Further, since these carbide particles have a higher melting point than the inner layer material, they are distributed on the outer peripheral surface in a cast-molded state. Therefore, the carbide particles and the inner layer material adhere very strongly.

[0007]

As the adhesion of the carbide coating on the outer peripheral surface of the sink roll is strong, the carbide coating is only worn by the steel plate to be plated, and the roll can be used without causing peeling. Therefore, the maintenance cost can be remarkably reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a centrifugal casting apparatus, in which a mold (1) is rotatably supported by receiving rollers (2) and (2) in a horizontal posture. Annular frames (3) and (3) are detachably arranged on both sides of the mold (1). Install the hopper (4) close to one end of the mold (1). A container (5) containing carbide particles is arranged near the upper part of the hopper (4), and the carbide particles are put into the hopper (4) together with the molten metal from the ladle (6).

In the example, a mold rotating at 1200 rpm
(Inner diameter 140 mm, length 520 mm), in weight% Cr: 18
%, Mo: 2%, Ni: 8%, and the balance substantially consisting of Fe together with WC particles having an average particle size of 100 μm, and centrifugal casting was performed. The weight of the melt used was 35 kg and the weight of the WC particles was 15 kg. As a result, the WC coating layer 5m
A centrifugal casting tube with m and inner layer of 20 mm was made. The specific gravity of the molten metal is about 8.0 and the specific gravity of WC is about 15.8.

A sink roll is made from this centrifugal casting pipe,
Although it is used in a molten zinc experimental facility, the carbide coating does not peel off even after about 5 months have passed since its use.

In the embodiment, the inner layer material is 18-8.
Although stainless steel was used, it goes without saying that it is not limited to this. Any material having a low specific gravity with respect to the above-mentioned three types of carbides can be used. However,
In the case of a sink roll having a structure in which the inner layer portion is in contact with molten zinc, a material having corrosion resistance against molten zinc must be selected.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a centrifugal casting device.

[Explanation of symbols]

 (1) Mold (2) Receiving roller (3) Annular frame (4) Hopper (6) Ladle

Claims (1)

[Claims] 1. A method of producing a sink roll for use in a hot dip galvanizing facility, the method comprising forming a carbide layer having excellent zinc corrosion resistance and wear resistance on the outer peripheral surface, and having an average particle size of 50 to 200 μm. And WC or MoC
The carbide particles of the above are put into a centrifugal casting mold together with a molten metal having a smaller specific gravity than the carbide particles, and the carbide powder having a large specific gravity is solidified by concentrating on the outer peripheral surface of the molten metal by the action of centrifugal force to cast the carbide particles. A method of manufacturing a sink roll in a hot dip galvanizing facility, which is characterized in that it is concentrated and distributed on the outer peripheral surface in a stuffed state.