JPS606267A - Production of roll - Google Patents

Abstract

PURPOSE:To obtain a roll to which a high carbon high Cr cast iron is welded by discharging downward the melt of the high carbon high Cr cast steel to the space between the core part of a steel roll and a master mold thereof and welding the cast iron to the core part after the surface of the core part heats up to the m.p. of the cast iron or above. CONSTITUTION:A casting mold 2 is concentrically disposed around the core part 1 of a steel roll and a separately melted high carbon high Cr cast iron 7 is discharged downward into the space between both. A stopper 9 is closed after the outside surface of the core part 1 attains the m.p. of the cast iron 7 or above. The m.p. of the cast iron 7 in this stage is, for example, about 1,170 deg.C and the temp. of the molten metal is about 1,600 deg.C. Then the molten layer 8 of the cast iron 7 poured into the space between the core part 1 and the mold 2 is welded to the core part 1. The double-layered roll in which the high carbon high Cr cast iron having excellent resistance to wear is welded on the outside surface of the core part of the steel roll is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a roll for crushing coal, ore, cement, etc.

Rolls for crushing coal, ore, or cement, etc. are integrally cast rolls depending on the manufacturing method.

There are three types: double centrifugal casting rolls and welding overlay rolls.

An overview of each is shown below.

(1) Integrated casting roll A wear-resistant material such as hard cast iron or high chromium cast iron is cast into a sand mold or metal mold, and the entire roll is made of this wear-resistant material.

(2) Two-layer centrifugal casting roll This is a two-layer roll manufactured by centrifugal casting by casting a wear-resistant material into the outer layer and then casting cast iron into the inner layer. Since the inner layer is cast iron with excellent machinability, machining of the inner surface is easier than with integral casting rolls.

(3) High carbon high chromium welding rod (diameter 3 to 4 mm, chemical composition example C: 3.5%, s1: o,
6%, Mn: 1.2%, Cr: 20.1%,
Nb: 3.5%, MO: 4.6%, balance Fe
) is a roll manufactured by overlay.

However, each role has its drawbacks:

(1) Integral casting roll Usually, the inner surface of the roll is rubbed against the shaft, so machining is required. However, in the case of a one-piece roll, the entire roll is manufactured from a wear-resistant material with a Shore hardness of 80 or more, which requires a long time for machining, resulting in an increase in the cost of the roll.

(2) Double-layer centrifugal casting roll In order to manufacture this roll, after casting the outer layer metal, the inner layer is cast while the entire outer layer is in a red-hot state to improve fusion, so the mixing area of the inner and outer layers is wide. , it is difficult to reduce the outer layer thickness. Furthermore, in order to improve the casting of the outer layer and the inner layer, the casting interval between the outer layer and the inner layer and the respective casting temperatures must be strictly controlled, which requires advanced casting technology.

(3) The diameter of the overlay roll welding rod is relatively small, 3 to 4 mm, and the welding speed is slow, so welding takes a long time and increases the cost of the roll.

The present invention solves the above-mentioned drawbacks, and provides a material that is easy to machine, has a thin outer layer, is easy to cast, and has excellent wear resistance.
Moreover, it provides an inexpensive method for manufacturing rolls.

That is, the present invention installs an outer mold around the core of a steel yarn roll concentrically with the core of the roll, and drains separately melted high-carbon, high-chromium cast iron into the gap between the roll core and the steel thread roll. A method for producing a high-carbon, high-chromium cast iron fusion roll, which comprises making the outer surface of the yarn roll core above the melting point of the high-carbon, high-chromium cast iron, and then fusing the high-carbon, high-chromium cast iron to the roll core. It is related to.

The present invention can be advantageously applied to a method of manufacturing rolls for mills that crush coal, ore, cement, and the like.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

1 and 2 show an embodiment of the method of the invention.

Figure 1 shows an outer mold installed around the roll in a circular pattern with the roll core, and separately melted high chromium cast iron molten metal is poured into the gap between the roll core and the outer mold and discharged. It is a diagram showing the situation. 1 is a roll core made of a steel thread material to be fused, and 2 is an outer mold for casting high carbon, high chromium cast iron molten metal onto the outer surface of the roll core 1. 3 is outer mold 2
An upper die installed above the roll core 1 also serves as a pouring port and a feeder. 4 is a lower mold located at the lower end of the outer mold 2, and 5 is a support stand.

6 is a ladle for casting high carbon, high chromium cast iron molten metal 7.

8Fi The molten metal 7 is poured into the gap between the roll core 1 and the outer mold 2 and forms a fusion layer. 9r/i This is a stopper plate for stopping the outflow. 10 is the residual molten metal 11 discharged downstream
Figure 2 shows that the surface of the steel thread roll core 1 has reached the melting point or higher of high chromium cast iron, so the stopper plate 9 that prevents the molten metal from flowing out is closed, and the roll core FIG. 3 is a diagram showing a state in which high carbon, high chromium cast iron molten metal is poured and filled into the gap between the mold and the mold.

One embodiment of the present invention will be described based on FIGS. 1 and 2. FIG. The roll core 1 is made of carbon steel (S25C),
The outer diameter was set to be twice the thickness of the adhesive layer (20 mm) than the finished roll dimension.

After the outer mold 2 of the mold made with a metal mold or sand mold was arranged in a concentric circle with the roll core 1, separately melted high carbon high chromium cast iron molten metal was poured into the gap between the roll core 1 and the outer mold 2. . At this time, the stopper 9 is opened so that the lower part of the gap is open and the molten metal flows down and is discharged. The temperature of the poured molten metal is 1,600°C, and the temperature of the outer surface of the roll gradually rises as it is heated by the molten metal flowing down. Separately melted high carbon high chromium cast iron molten metal 7 (e.g. C: 5.2
q6. Si: 0.45%, Mn: 1.35%, Cr: 22.0ql), Mo: 3.0%.

The melting point (solidus temperature) of Nl): 5.7) is 1.17
It is 0°C.

The roll outer surface temperature is measured from the upper surface of the roll with a brightness thermometer or a radiation thermometer, and the molten metal is discharged downward until the outer surface temperature reaches the melting point of the cast molten metal. The relationship between the size of the roll core and the discharge time of the molten metal is shorter as the diameter of the roll core is smaller and longer as the diameter of the roll core is wider. If necessary, the outer surface of the roll core can be preheated using a propane burner or the like to shorten the time required for the molten metal to flow down and be discharged.

The reason for heating the roll's outer surface with molten metal until it reaches the melting point of the high carbon, high chromium cast iron that is the fusion layer is to ensure complete fusion between the copper material of the roll core and the high carbon, high chromium cast iron. It's for a reason. The melting point of steel thread material is approximately 15)t, 500°C, and the solidus temperature of high carbon, high chromium cast iron is approximately 1.1.
5Q to 1,200°C. In order to achieve complete fusion, it is necessary that the cast high carbon high chromium cast iron does not solidify while the roll outer surface and the high carbon high chromium cast iron that is the fusion layer form an intermediate alloy and are completely fused. In order to achieve this, the interface temperature must be maintained above the melting point (solidus temperature) of the fused layer.

In this example, high carbon, high chromium cast iron was poured and discharged until the surface temperature of the roll row reached 1,170°C. The discharged molten metal is collected in a ladle prepared in advance and returned to the melting furnace. When the roll outer surface temperature reached the melting point of high carbon, high chromium cast iron or higher, the stopper plate 9 was closed, and the gap between the roll core and the outer mold was filled with molten metal at a temperature of 1600° C. and cooled. After cooling the fusion layer 8, the upper mold 3. When the lower mold 4 and the outer mold 2 were removed, a roll was obtained in which high carbon, high chromium cast iron having excellent wear resistance was fused to the outer surface of the roll core 1. The hardness of the outer surface of the fused roll is 85 to 9 in Shore hardness.
0 was obtained.

Furthermore, in the method of the present invention, carbon steel, low alloy steel, high alloy steel (stainless steel), etc. are used as the steel thread roll core.

The present invention has the technical configuration detailed above, and as a result, the following effects can be achieved.

(1) Since the outer surface of the roll core is made to have a temperature higher than the melting point of the high carbon, high chromium cast iron that is the fusion layer, and the high carbon, high chromium cast iron is fused, the fusion with the roll core surface is extremely deep.

(2) Since the outer hardened layer (high carbon, high chromium cast iron, Shore hardness 85 or higher) is fused by casting, it can be manufactured in a shorter time compared to welded overlay rolls, and the fused layer thickness can be adjusted to any desired thickness. rolls can be manufactured.

(3) Machining of the roll core is easy.

(4) No special heating equipment is required for fusion.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are explanatory diagrams of one embodiment of the present invention,
Fig. 1 shows a state in which the high carbon, high chromium cast iron serving as the outer layer is discharged downward, and Fig. 2 shows a state in which the high carbon, high chromium cast iron is fused to the inner layer. Sub-agents 1) Meifuku agent Ryo Hagiwara -

Claims (1)

[Claims] An outer mold is installed around the core of the steel yarn roll in a concentric circle with the core of the roll, and separately melted high-carbon, high-chromium cast iron is discharged into the gap between the core and the core of the steel yarn roll. A method for producing a high-carbon, high-chromium cast iron fusion roll, which comprises making the surface of the high-carbon, high-chromium cast iron higher than its melting point, and then fusing the high-carbon, high-chromium cast iron to the core of the roll.