JPS59101268A - Production of build-up roll by tinkering - Google Patents

Abstract

PURPOSE:To deposit thoroughly a high carbon high chromium cast iron in the core part of a roll heated to a specific temp. by installing the core part of said roll at the center of a casting mold concentrically with said mold, and pouring a specific molten metal into the spacing between the core part of the roll and the casting mold. CONSTITUTION:A core part 1 of a roll is installed in a high frequency induction heating coil 2 and the outside surface of the part 1 is heated to >=500 deg.C. The part 1 is then installed on a bottom mold 5 and at the center of a master mold 3 concentrically with the mold 3. A top mold 4 is installed on the part 1 and the mold 3. A molten high carbon high chromium cast iron (molten high carbon high chromium cast iron contg. >=3.0% C, >=0.5% Si, >=0.5% Mn, >=13% Cr, and others including 1 or >=2 kinds among V, Nb, Mo, W) melted separately in a melting furnace is poured into the spacing between the part 1 and the mold 3. A build-up roll by tinkering wherein the high carbon high chromium cast iron is deposited on the outside surface of the part 1 is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a roll, and particularly to a method for manufacturing a roll that has excellent machinability and wear resistance and is inexpensive to manufacture.

Rolls that require excellent wear resistance can be broadly divided into monolithic casting rolls based on manufacturing method.

There are five types: double-layer centrifugal casting rolls and weld overlay rolls. An overview of each is shown below.

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

(2) Two-layer centrifugal casting roll A two-layer roll manufactured by centrifugal casting, incorporating wear-resistant material 'a-fi' into the outer layer and then casting cast iron into the inner layer.The inner layer is made of cast iron with excellent machinability. Because of this, machining of the inner surface is easier than with integral casting rolls.

(3) High carbon high chromium welding rod (5
~4φ, chemical component examples 0:A5%, 81:116%, M
n: 1.2%, cr: 2 (11%, N'b: 35%, M
o: 4.6%).

However, each type of roll has the following drawbacks.〇(1) One-piece integrated roll Normally, the inner surface of the roll is rubbed against the shaft, so machining is required, but it is difficult to machine the inner surface of the roll. Since they are manufactured from hard, wear-resistant materials, machining takes a long time, which increases the cost of the rolls.

(2) Two-layer centrifugal casting roll In order to improve the rusting of the outer and inner layers, the casting interval between the outer and inner layers and the respective casting temperatures must be strictly controlled, so advanced bait making technology is required. 〇(3) The diameter of the welding electrode of the welding overlay roll is relatively small at 5 to 4 mm, and the rod movement speed (welding speed) is slow, so the welding time takes a long time.
This increases the cost of rolls.

The present invention solves the above-mentioned drawbacks and provides a method for manufacturing a roll that is easy to machine, has excellent wear resistance, and is inexpensive. The outer surface of the roll core is heated by high frequency induction to a temperature of 500°C or higher, and the heated roll core is placed concentrically with the mold in the center of a separately prepared fC@ mold, and the roll core and the mold are heated. Separately dissolved in the gap between 0:! LO% or more, Si: 0.51 or more,
Mn: α5% or more, Cr: 15% or more, and other ■.

A casting machine characterized by casting a high-carbon, high-chromium cast iron molten metal containing one or more of Nb, MO, and W, and completely welding the high-carbon, high-chromium cast iron to the roll core. INDUSTRIAL APPLICABILITY The method of the present invention, which relates to a method for producing a built-up roll, can be applied to the production of mill rolls for grinding coal, raw ore, and the like.

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

Figures 1 and 2 are diagrams for explaining one embodiment of the method of the present invention. Figure 1 shows the situation in which the outer surface of the roll core is heated by high frequency induction, and Figure 2 shows the state in which the outer surface of the roll core is heated by high frequency induction. The sound of high-carbon, high-chromium cast iron molten metal being completely cast into the core section. 2b are terminals of heating coils. Reference numeral 5 denotes an outer mold for casting high-carbon, high-chromium rotten iron molten metal 7 on the outer surface of the roll core 1, and here a water-cooled mold with cooling water passed inside is shown. 5a and 5b are an inlet pipe and an outlet pipe for cooling water, respectively. -04 is an upper mold installed on the outer mold 5 and the roll core 1, and also serves as a pouring port and a feeder. 5 is a lower mold 0 used for casting in the gap between the roll core 1 and the outer mold 5.
6 is a ladle for casting high carbon high chromium cast iron molten metal 0
8 represents the fC molten metal formed by pouring the molten metal 7 into the gap between the outer mold 5 and the roll core 1, and 9 represents the cast layer in which the molten metal 8 solidified in the roll core 1.

Next, a specific example will be explained based on FIGS. 1 and 2.

The roll core IF'i is made of carbon steel cast steel (BC46), and its radius is determined from the finished dimensions by the thickness of the hardfacing layer 50.
Only the parrot has a smaller shape. This roll core 1 was placed in a high-frequency induction heating coil 2, and the outer surface was heated to about 700°C by high-frequency induction heat. The reason why the temperature is higher than 500°C is that if the temperature is less than 500°C, the cast layer and the roll core will not be sufficiently cast, and the cast layer may peel off and fall off during use of the roll. In addition, the upper limit of the heating temperature does not need to be extremely high, and is preferably about 1000°C in consideration of workability. Furthermore, the heating temperature varies depending on the size of the roll core. The smaller the roll core, the easier it is to cool down before the entire casting layer is cast, so as a general rule, the larger the roll core, the lower the temperature, and the smaller the roll core, the higher the temperature. 5 in a concentric circle with the outer mold 5, and set the upper mold 4 on top of the roll core 1 and the outer mold 5 at 7'C.

Separately, high carbon high chromium cast iron molten metal (0
:! L62%, 81:0.7%, Mn:
1.1%, Or: 22.1%, Nb: 4.1
%, MO: a, 5%) 7K Molten metal was poured into the gap between the roll core 1 and the outer mold 5 using a ladle 6.

Since the outer mold 5 has been cooled, the poured molten metal 8 first solidifies from the outer mold 5, which has a large cooling capacity, and solidifies to the upper end of the roll.

After solidification of the molten metal 8 is completed, the upper mold 4. Lower mold 5 and outer mold 9
'@: When removed, a cast overlay roll in which high carbon, high chromium cast iron was welded to the outer surface of the roll core 1 was obtained.

In the method of the present invention, the chemical composition of high carbon, high chromium cast iron is reduced to O:! LO% or more, 81:0.5% or more, Mn: [15
% or more, Or: 15% or more, and in addition, V, N
Containing one or more of B, Mo, and W is used to improve the wear resistance of the casting layer.
Normal high chromium cast iron containing 15% or more of carbide-forming elements V, Nb, and Mo.

This is to add one or more types of W and to adjust C'i& to 0% or more accordingly.

It should be noted that if Cr exceeds 50%, the base structure 75 (ferrite will be formed and the wear resistance will decrease), and the upper limit is preferably 50%.

Also, C is C! It is an element that forms carbides together with r, V, Nb, Mo and W, and when its amount decreases,
The amount of carbide decreases and the wear resistance decreases, so a minimum of 50% is necessary.On the other hand, if the amount of C increases by 75 balls, the amount of carbide increases, but if it is excessive, it becomes brittle and breaks easily. Therefore, it is preferable that the upper limit is 5.0.

Sl and Mn are necessary as deoxidizing agents when completely melting steel materials, and in order to exert their effect,
081, which needs to be added at least 0.5%, is a graphite-forming element, so as the amount of 81 increases, the amount of carbide formation decreases and the wear resistance also decreases, so the upper limit is 2.0%.
It is preferable that Since Mn is an austenite-forming element, an increase in Mn increases the base structure of austenite and reduces wear resistance, so the upper limit is preferably 1.5%.

One or more of V, NblMo, and W are added as carbide-forming elements as described above, and the amounts of each of these elements to be added are preferably as follows.

If ① is less than 1%, the amount of Va carbide formed is small, and the full effect of improving wear resistance cannot be achieved.On the other hand, if it is more than 10%, the amount of carbide becomes excessive, making it brittle and easy to break. A 10% addition is preferred.

When Nt+ is less than 0.5%, the amount of NbC carbide precipitated is small and no significant effect on improving wear resistance can be shown.
On the other hand, if it exceeds 8%, the amount of NbC carbide becomes excessive.
0.5 to 8 as it not only becomes brittle but also increases cost.
% addition is preferred.

If MO is less than 0.5%, the amount of Mo2C carbide precipitated will be insufficient and the improvement in wear resistance will be insufficient.On the other hand, if it is more than 5%, the amount of MO2C carbide will be excessive, causing cracking and cracking. , preferably 0.5 to 5%.

When W is less than 0.5%, the amount of WC carbide precipitated is insufficient;
Addition of 0.5 to 5% is preferable since the improvement in wear resistance is insufficient, and on the other hand, if the number of scratches exceeds 5, the amount of we carbide becomes excessive, making it easy to crack and increasing costs.

For reference, an example of the chemical composition of ordinary high chromium cast iron is shown below according to the BS standard.

Furthermore, in the method of the present invention, carbon steel, low alloy steel, high alloy steel (stainless steel), etc. are used as the steel yarn roll core. This is the general rule.

+11 Since high carbon, high chromium cast iron is cast after the outer surface of the roll core is preheated to 500°C or higher, the fit between the roll core and the roll core is extremely good.

(2) Since the outer hardened layer (high carbon, high chromium cast iron) is cast by casting, it can be manufactured in a shorter time than welded overlay rolls.

(3) Machining of the roll core is easy.

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams for explaining one embodiment of the method of the present invention. Sub-Agents 1) Meifuku Agent Ryo Hagiwara - Figure 1

Claims (1)

[Claims] The outer surface of a cylindrical or cylindrical steel yarn roll core is heated by high-frequency induction to 500°C or higher, and the heated roll core is placed in the center of a separately prepared mold concentrically with the mold, and the roll core C: 50% or more, Si: Q: 5% or more, Mn: 0.5% or more, Or
: Casting a high carbon, high chromium cast iron molten metal containing at least 15 iron and one or more of V, Nb, Mo, and W, and completely injecting the high carbon, high chromium 6 iron into the roll core. A method for manufacturing a cast overlay roll, characterized by welding it to a cast overlay roll.