JP2001232406A - Composite rolling roll and method of manufacturing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a composite rolling roll without defective welding or the like by expanding the condition range that an outer layer and an inner layer are weldable. SOLUTION: In the composite rolling roll provided with the outer layer 12 in a shell layer and the inner layer 14 on the side of the core part, a sleeve 20 consisting of steel whose C-content is <=0.25 wt.% is interposed between the outer layer 12 and the inner layer 14 and the sleeve 20 is respectively metallurgically integrated into the outer layer 12 and inner layer 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite roll for rolling used for rolling steel wires and bars.

[0002]

2. Description of the Related Art Rolling rolls used for rolling structural materials such as wires and bars are required to have abrasion resistance on the outer shell side in contact with the material to be rolled and toughness on the core side. This type of rolling roll uses a tough material such as ductile cast iron or graphite steel for the inner layer on the core side, and a wear-resistant material such as high-speed cast iron material for the outer layer on the outer shell side. There is a composite roll in which the inner periphery is welded and integrated.

[0003] This composite roll for rolling is manufactured by first forming a cylindrical body as an outer layer by casting, and then casting a molten metal for an inner layer so as to cast at least the inner surface and both end surfaces of the cylindrical body. You. When casting the inner layer, the inner surface of the outer layer
The inner layer melts again by the heat of the inner layer molten metal, solidifies again with the inner layer, and the inner layer and the outer layer are welded and integrated.

[0004]

When a composite roll for rolling is produced by the above-mentioned method, there is a disadvantage that when the molten metal for the inner layer is cast, the welding conditions for the inner layer and the outer layer differ depending on the position of the roll. there were. As a result, in some parts, the temperature of the interface does not rise to the melting point of the outer layer material and welding failure may occur.On the other hand, in the part where the temperature of the outer layer rises too much, a large amount of outer layer material becomes May melt away.

[0005] Furthermore, a cast iron material having a high C content has a lower freezing point than a steel-based material, but has a high melting point because it contains carbide and graphite having poor weldability. In other words, although the high-C material hardly melts on the surface, once it starts melting,
Because of its low freezing point, it is a material that melts rapidly, has a very narrow range of conditions that can be welded, and is difficult to control.

[0006] These welding conditions become more difficult to control as the welding interface between the outer layer and the inner layer becomes wider, that is, as the rolled composite roll produced becomes larger. Therefore, it is difficult to perform stable welding by using the above manufacturing method for manufacturing a large composite roll.

It is an object of the present invention to provide a method for manufacturing a composite roll for rolling by expanding welding conditions for an outer layer and an inner layer so that poor welding does not occur.

[0008]

Means for Solving the Problems In order to solve the above problems, a composite roll for rolling (10) of the present invention comprises an outer layer (1) on the outer shell side.
2) In the rolling composite roll having the inner layer (14) on the core side, the content of C is 0.2 between the outer layer (12) and the inner layer (14).
A cylindrical body (20) made of a steel material of 5% by weight or less is interposed, and the cylindrical body (20) is metallurgically integrated with an outer layer (12) and an inner layer (14).

[0009]

The steel having a C content of 0.25% by weight or less has excellent weldability to both the outer layer material and the inner layer material. Therefore, by integrating the outer layer (12) and the inner layer (14) via the steel tubular body (20), the range of welding conditions can be expanded, and the occurrence of welding defects can be prevented. it can.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A composite roll for rolling according to the present invention (10)
Is a method in which a cylindrical body (20) made of a steel material having a C content of 0.25% by weight or less is interposed between an outer layer (12) on the outer shell side and an inner layer (14) on the core side. , The outer layer (12), the cylindrical body (20) and the inner layer are metallurgically integrated.

The cylindrical body (20) disposed between the outer layer (12) and the inner layer (14) is a cylindrical body made of a steel material having a C content of 0.25% by weight or less. The outer diameter of the cylindrical body (20) is the same as the inner diameter of the outer layer (12) of the produced composite roll for rolling. Tube (2
The thickness of 0) is desirably formed to about 3 to 10 mm.
To make the thickness about 3 to 10 mm, if it is thinner than about 3 mm,
This is because it is difficult to maintain a perfect circle and processing becomes difficult. Also, when it becomes thicker than about 10 mm,
This is because the amount of heat required to heat the cylindrical body (20), which is required when welding the (20) and the outer layer (12) or the inner layer (14), becomes large. It is desirable that the surface of the cylindrical body (20) be plated with Ni having a thickness of about 10 μm. By performing Ni plating, wettability with the molten metal can be improved, and oxidation during preheating can be prevented. In addition, when fine irregularities are formed on the surface of the cylindrical body (20) or the surface is roughened, the weldability between the outer layer material and the inner layer material can be further improved.

Either the outer layer (12) or the inner layer (14) is
It is optional to perform welding and integration with (20), and they may be performed simultaneously. As described later, the fusion of the outer layer (12) and the cylindrical body (20) is performed by casting a molten metal for the outer layer outside the cylindrical body (20) (Embodiment 1) or hot isostatic pressing (HIP). ) (Embodiment 2). Further, welding and integration of the inner layer (14) and the cylindrical body (20) can be performed by casting the inner layer molten metal inside the cylindrical body (20) (Embodiment 3).

The material constituting the cylindrical body (20) has a C content of 0.25% by weight or less, and the balance is substantially Fe, and examples thereof include so-called general structural steel or mild steel. This kind of steel material has a ferrite structure and carbide is hardly precipitated, so the range of conditions that can be welded is wide,
This is because it is a material with excellent weldability due to cast-in.

As the material constituting the inner layer (14), a material which crystallizes graphite such as ductile cast iron, flaky graphite cast iron or graphite steel is preferably used. These materials are excellent in toughness, and can absorb the load by flattening the roll at the time of overload, thereby improving the accident resistance. Among these materials, it is more desirable to use ductile cast iron. This is because ductile iron is a material that does not easily cause shrinkage cavities during casting.

As ductile cast iron, C: 2.5-4.0
% (% By weight, the same applies hereinafter), Si: 1.3 to 3.5%, Mn:
0.2 to 1.5%, P: 0.2% or less, S: 0.2% or less,
Ni: 3.0% or less, Cr: 2.0% or less, Mo: 2.0
% Or less, Mg: 0.02 to 0.1%, with the balance substantially consisting of Fe.

As flaky graphite cast iron, C: 2.5-4.0%
(% By weight, hereinafter the same), Si: 0.8 to 2.5%, Mn:
0.2 to 1.5%, P: 0.2% or less, S: 0.2% or less,
Ni: 3.0% or less, Cr: 2.0% or less, Mo: 2.0
% Or less and the balance substantially consisting of Fe.

As graphite steel, C: 1.0 to 2.3% (% by weight, the same applies hereinafter), Si: 0.5 to 3.0%, Mn: 0.2 to 0.2%
1.5%, P: 0.2% or less, S: 0.2% or less, Ni:
Examples include those containing 3.0% or less, Cr: 2.0% or less, and Mo: 2.0% or less, and the balance substantially consisting of Fe.

As the material forming the outer layer (12), a high-speed cast iron material having excellent wear resistance is preferably used. As the high-speed cast iron material, C: 1.0 to 4.0% (% by weight, the same applies hereinafter), Si: 0.1 to 2.0%, Mn: 0.1 to 2.0%,
Cr: 3.0 to 15.0%, Mo: 0.1 to 9.0%, W:
1.5 to 10.0%, one containing V or Nb or Nb in a total of 3.0 to 10.0%, and the balance substantially consisting of Fe. , Ni: 3.0
To 10.0%. As another example of the high-speed cast iron material, C: 1.8 to 3.6% (% by weight, the same applies hereinafter),
Si: 1.0 to 3.5%, Mn: 0.1 to 2.0%, Cr:
0.2 to 10.0%, Mo: 0.1 to 10.0%, W: 0.1%
1 to 10.0%, 1.5 in total of one or two of V and Nb
And the balance substantially consisting of Fe, and if necessary, Ni: 0.5 to 1%.
0.0%, Co: 0.5 to 10.0%, B: 0.01 to 0.5%
50%, Al: 0.01 to 0.50%, Ti: 0.01 to
At least one selected from the group consisting of 0.50% and Zr: 0.01 to 0.50% can be included.

The following is a description of a composite roll (10) for rolling according to the present invention.
A preferred manufacturing method will be described. Embodiment 1 In the first embodiment, the outer layer (12) is cast outside the cylindrical body (20).
Then, an embodiment in which the inner layer (14) is cast inside the cylindrical body. << Integration of Outer Layer and Cylindrical Body >> As shown in FIG.
Under-poured stationary with sand mold (43) under chiller (42)
The outer layer (12) can be cast using the casting mold (40).
The chiller (42) is slightly larger than the outer diameter of the outer layer (12) to be made.
It is formed with a large inner diameter. At the lower end of the chiller (42)
Has a spout (44) for the molten metal for the outer layer,
A discharge port (45) for molten metal is formed beside. The chiller
Coating mold (48) is applied to the inner surface in advance to facilitate release
It is desirable to keep. Near the center of the mold (40), mild steel
A cylindrical body (20), and the lower end of the cylindrical body (20) is buried in a sand mold (43).
And fix it. The length of the cylinder (20) depends on the machine
Processed part and part to be embedded in sand mold (43)
In consideration of the length of the outer layer is more than about 150mm
Use things. The molten metal outlet (45) is connected to the cylindrical body (2
It is formed at a position slightly lower than the upper end of (0). Under chiller
The molten metal for the outer layer is poured from the spout (44) at the end. For outer layer
The casting temperature of hot water should be above freezing point (liquidus) + 100 ℃
Is desirable. The molten metal for the outer layer poured into the cylinder (2
0) and the chiller (42), and do not heat the cylinder (20).
Rises up to the outlet (45) and is discharged sequentially to the outside.
You. The amount of the outer layer molten metal to be injected is about 2% of the weight of the cylindrical body.
Desirably, it is 0 times or more. In this way, the outer layer
Injecting hot water more than about 20 times the weight of the cylinder (20)
(20) is heated sufficiently to re-melt the outer peripheral surface of the cylindrical body (20).
That's because. The outer peripheral surface of the cylindrical body (20) melts
When the injection of the melt for the outer layer is stopped at the stage
Coagulation starts and the outer layer (12) and the cylindrical body (20) are welded and integrated.
You.

<< Integration of Inner Layer and Cylindrical Body >> After the molten metal for the outer layer solidifies, the outer layer (12) and the cylindrical body (20), which have been welded and integrated, are cast into a mold.
It is taken out of (40), cut to a desired length, and placed in a bottom-cast static casting mold (50) shown in FIG. 2 to cast the inner layer (14). The mold (50) has a sand mold (53) formed in an outer frame (51), and has a molten metal pouring port (54) at a lower end and a molten metal discharge port (55) at an upper end. . The integrated outer layer (12) and the cylindrical body (20) are arranged at a height approximately at the center of the sand mold (53), and the inner peripheral surface of the cylindrical body (20) is substantially flush with the inner surface of the sand mold (53). Or cylindrical
(20) so that it protrudes more inward than the sand mold (53).
Before pouring the inner layer molten metal, it is desirable to preheat the inner surface of the cylinder in order to prevent cracking.

In this state, the inner layer molten metal is poured from the lower pouring opening (54). The casting temperature of the inner layer molten metal is preferably set to a solidification point (liquidus) + 100 ° C. or higher. The poured molten metal for the inner layer flows into the sand mold (53),
0) is heated while heating, reaches the discharge port (55), and is sequentially discharged to the outside. It is desirable that the amount of the inner layer molten metal to be poured is about 20 times or more the total weight of the outer layer (12) and the cylindrical body (20). Thus, the molten metal for the inner layer and the outer layer (12)
The reason why the injection is made at least about 20 times the weight of (20) is to sufficiently heat the cylinder (20) and re-melt the inner peripheral surface of the cylinder (20). When the injection of the inner layer molten metal is stopped at the stage where the inner peripheral surface of the cylindrical body (20) is completely re-melted, the inner layer molten metal starts to solidify, and the inner layer (14) and the cylindrical body (20) are welded. Be integrated.

After the melt for the inner layer has solidified, the roll is placed in a mold (5
0), take out the prescribed machining, as usual,
After heating to a temperature of about 1000 ° C. or more, about 300 to 40
A quenching heat treatment for cooling at a cooling rate of 0 ° C./h is performed, and thereafter, a tempering heat treatment is performed once or several times at a temperature of about 500 to 600 ° C., and a finishing process is performed. A roll (10) is produced.

When integrating the outer layer (12) and the cylindrical body (20),
In the above embodiment, the overflowed outer layer molten metal is discharged to the outside from the discharge port (45) .However, without providing the molten metal discharge port (45), the outer layer molten metal overflowing from the upper end of the cylindrical body is formed into the cylindrical body ( After the solidification is completed, the outer layer material may be taken out inside the cylindrical body (20).
In this case, a coating mold is applied to the inner peripheral surface of the cylindrical body (20).
By causing the molten metal for the outer layer to flow into the inner peripheral surface of the cylindrical body (20) in this manner, the heating efficiency of the cylindrical body (20) can be increased, and the amount of the molten metal for the outer layer required for heating can be reduced.

In the case of manufacturing the roll for composite roll (10) having the caliber formed thereon, as shown in FIG. 4, a cylindrical body (20) having irregularities (22) along the caliber shape is used. ,
After casting the outer layer (12) by the same method as above, the inner layer
(14) is cast, and the outer layer (1
A desired caliber may be formed on the surface of 2). According to this method, since the outer layer (12) has a shape corresponding to the caliber not only on the surface but also on the inner peripheral side, the thickness of the outer layer (12) can be made substantially constant throughout.

Embodiment 2 In Embodiment 2, the outer layer (12) and the cylindrical body (20) are welded and integrated by HIP. As the outer layer material, a powdered material is used. In this embodiment, the cylinder (20) corresponds to the inner cylinder of the double cylinder (60) having the annular space (61). After the powder outer layer material is accommodated in the annular space (61) of the double cylindrical body (60), the annular space (61) is evacuated and sealed, and then, as shown in FIG. By performing the above, the outer layer material is sintered, and is integrated by diffusion bonding with the double cylindrical body (60).

Next, the outer layer (12) is cast to cast the inner layer (14).
The HIP-sintered double cylindrical body (60) is placed in a bottom-cast static casting mold (50) shown in FIG. The outer mold (50)
A sand mold (53) is formed in 1), and a molten metal pouring port (54) is formed at a lower end, and a molten metal discharge port (55) is formed at an upper end. The double cylindrical body (60) with the outer layer (12) integrated is a sand mold (5
3), the inner peripheral surface of the cylindrical body (20), which is the inner cylindrical body of the double cylindrical body (60), is substantially flush with the inner surface of the sand mold (53) or the cylindrical body ( 20) so that it protrudes more inward than the sand mold (53). In this state, the molten metal for the inner layer is poured from the lower spout (54), and the cylindrical body (20) (the inner cylinder of the double cylindrical body (60)) and the inner layer (14)
Are integrated by welding. The injection of the molten metal is the same as in the first embodiment, and thus the description is omitted.

According to the above-mentioned method, a roll in which the outer layer (12) and the cylinder (20) and the inner layer (14) and the cylinder (20) are welded and integrated, respectively, is obtained. After the inner layer is solidified, the roll is taken out of the mold (50), the exposed portion of the double cylindrical body (60) is shaved off, and subjected to predetermined machining, heat treatment, and finishing in the same manner as in the first embodiment. A roll (10) is produced.

The production cost can be reduced by preparing the outer layer (12) by HIP processing. Also, there is an advantage that the raw material after the HIP processing can be put into a mold (50) as it is and the inner layer (14) can be cast.

Embodiment 3 Embodiment 3 is an example in which the inner layer (14) and the outer layer (12) are cast almost at the same time. In this embodiment, a bottom-cast still casting mold (70) as shown in FIG. 7 is used. The mold (70) is a mold in which sand molds (72) and (73) are arranged above and below a chiller (71).
(20) is disposed with its upper and lower ends buried in sand molds (72) and (73), respectively. The inner layer (14) is injected into a space continuous inside the cylindrical body (20). The lower sand mold (73) has a spout (7
4) A discharge port (75) for the inner layer molten metal is formed in the upper sand mold (72). The outer layer (12) consists of sand molds (72) (73) and chillers (7
It is injected into the space formed by 1) and the cylinder (20).
At the lower end of the space where the outer layer (12) is cast, a spout (7
6) The gas vent hole (77) is formed at the upper end. The inner surface of the chiller (71) is pre-coated to facilitate release.
(Not shown).

The molten metal for the inner layer and the molten metal for the outer layer are poured into the mold (70) having the above structure. The order of injection of the molten metal may be simultaneous or may be performed first, but since the material of the outer layer is expensive, the heating of the cylindrical body (20) is more difficult for the inner layer than for the outer layer. It is preferable to heat the cylinder (20) with the molten metal. In this case, the molten metal for the inner layer is injected first, and after sufficiently heating the cylindrical body (20), the molten metal for the outer layer is injected.

The molten metal for the inner layer is poured from the spout (74).
The injected molten metal for the inner layer flows into the inner layer space, where the cylindrical body (2
0) is heated while heating, reaches the discharge port (75), and is sequentially discharged to the outside. The amount of the inner layer molten metal to be injected is desirably about 20 times or more the weight of the cylindrical body. By the injection of the inner layer molten metal, the cylindrical body (20) is sufficiently heated, and the inner peripheral surface is almost completely re-melted. After the cylindrical body (20) is preheated by the inner layer melt, the outer layer melt is poured from the spout (76). Cylindrical body
Since (20) has already been preheated, the amount of the molten metal for the outer layer to be injected may be such that the molten metal for the outer layer reaches the gas vent hole (77). By the injection of the outer layer molten metal, the outer peripheral surface of the cylindrical body (20) is almost completely re-melted. After the inner layer melt and the outer layer melt are poured into the mold (70), the inner layer melt and the outer layer melt are solidified to form the inner layer (14), the cylindrical body (20), and the inner layer (1).
4) and the cylindrical body (20) are welded and integrated. Then, the first embodiment
By performing machining, heat treatment, and finishing in the same manner as described above, a composite roll for rolling (10) as shown in FIG. 3 is produced.

[0032]

EXAMPLE A composite roll for rolling was produced in the same manner as in Embodiment 1 by using a molten metal having the components shown in Table 1 (unit is% by weight, the balance being substantially Fe).

[0033]

[Table 1]

Hereinafter, dimensions, weight, and other conditions will be described. A cylinder made of mild steel having an outer diameter of 270 mm, a length of 800 mm, a thickness of 5 mm, and a weight of 26 kg was prepared, and the cylinder was placed inside a chiller having an inner diameter of 690 mm and a height of 800 mm at a casting portion. In addition, the cylindrical body was fixed to the sand mold by embedding the lower end of 50 mm in the sand mold. Between the chiller and the cylinder, 660 kg (about 25 times the weight of the cylinder) of the molten metal for the outer layer of the components shown in Table 1 is poured at a casting temperature of 1560 ° C., and solidified to weld and integrate the cylinder and the outer layer. I let it. Thereafter, machining was performed to make the outer layer outer diameter 380 mm, the cylindrical body inner diameter 264 mm, and the length 680 mm. The total weight of the integrated outer layer and the cylindrical body was 310 kg. Next, a 10 μm-thick Ni plating was applied to the inner surface of the cylindrical body, and the integrated outer layer and the cylindrical body were placed in a mold and preheated to 350 ° C. to prevent cracking. Casting temperature 13
7,500 kg were injected at 80 ° C. After the inner layer is solidified, the roll is removed from the mold, and from 1000 ° C. to 300 to 400
A quenching treatment of cooling at a temperature of ° C./h and a tempering treatment at 550 ° C. for 10 hours were performed three times. Hardness of outer layer surface at this time (Hs)
Was 84-86. Finally, the final finishing process is performed, outer layer outer diameter 360mm, outer layer length 650mm, outer layer thickness 4
A 5 mm rolling composite roll was produced.

The prepared composite roll for rolling was cut in the axial direction, and the joining state of the outer layer and the cylindrical body, and the joining state of the inner layer and the cylindrical body were examined.

The description of the above embodiments is for the purpose of illustrating the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a mold for casting an outer layer outside a cylindrical body according to a first embodiment.

FIG. 2 is a cross-sectional view of a mold for casting an inner layer inside a cylindrical body according to the first embodiment.

FIG. 3 is a cross-sectional view of the rolling composite roll of the present invention.

FIG. 4 is a cross-sectional view of a mold for producing an outer layer having a caliber shape.

FIG. 5 is a cross-sectional view of an outer layer and a double cylindrical body integrated by HIP according to a second embodiment.

FIG. 6 is a sectional view of a mold for casting an inner layer inside a cylindrical body according to a second embodiment.

FIG. 7 is a cross-sectional view of a mold for casting an inner layer inside a cylindrical body and an outer layer outside the cylindrical body according to the third embodiment.

[Explanation of symbols]

 (10) Composite roll for rolling (12) Outer layer (14) Inner layer (20) Cylindrical body

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (for reference) B22D 19/00 B22D 19/00 XY 19/16 19/16 D C22C 37/00 C22C 37/00 B (72) Invention Person Tatsuo Kawanaka 64 Nishimukaijima-cho, Amagasaki City, Hyogo Prefecture F-term in Kubota Amagasaki Plant (reference) 4E016 AA04 AA05 DA03 DA15 EA03 EA12 EA23 FA03

Claims (6)

[Claims] A composite roll for rolling comprising an outer layer (12) on the outer shell side and an inner layer (14) on the core side, wherein the content of C is between the outer layer (12) and the inner layer (14). A cylinder (20) made of steel material of 0.25% by weight or less is interposed, and the cylinder (2
0) is a composite roll for rolling, which is metallurgically integrated into the outer layer (12) and the inner layer (14). 2. The rolling composite roll according to claim 1, wherein the outer layer is a high-speed cast iron material containing 1.0% by weight or more of C. 3. The rolling composite roll according to claim 1, wherein the inner layer (14) is selected from the group consisting of ductile cast iron, flaky graphite cast iron and graphite steel. 4. A method for producing a composite roll for rolling comprising an outer layer (12) on the outer shell side and an inner layer (14) on the core side, wherein the C content is reduced into a substantially cylindrical mold (40). 0.25% by weight
The process of placing a cylinder (20) made of the following steel materials, a mold
(40) pouring the molten metal for the outer layer into the space formed between the cylindrical body (20), a step of metallurgically integrating the outer layer (12) on the outer peripheral surface of the cylindrical body (20), And a step of pouring molten metal for the inner layer inside the cylindrical body (20) to integrate the inner peripheral surface of the cylindrical body (20) and the inner layer (14) metallurgically. Method for producing a composite roll for rolling. 5. A method for producing a composite roll for rolling comprising an outer layer (12) on the outer shell side and an inner layer (14) on the core side, wherein the C content is reduced into a substantially cylindrical mold (70). 0.25% by weight
The process of placing a cylinder (20) made of the following steel materials, the cylinder
A step of pouring the inner layer molten metal into the inside of (20), metallurgically integrating the inner layer (14) on the inner peripheral surface of the cylindrical body (20), and a mold (7).
A step of pouring molten metal for an outer layer into a space formed between the outer cylinder (20) and the outer layer (12) in a metallurgical manner. A method for producing a composite roll for rolling. 6. A method for producing a composite roll for rolling comprising an outer layer (12) on the outer shell side and an inner layer (14) on the core side, comprising a steel material having a C content of 0.25% by weight or less. The annular space (61) of the double cylindrical body (60) accommodates the powdery outer layer material in the annular space (61), and after sealing the annular space (61), performs hot isostatic pressing to form a double layer with the outer layer material. Step of diffusing and joining the tubular body (60), the double tubular body (60) integrated with the outer layer (12) is cast
(50), and pouring the inner layer molten metal inside the double cylindrical body (60), the inner peripheral surface of the double cylindrical body (60) and the inner layer (1).
4. A method for producing a composite roll for rolling, comprising a step of metallurgically integrating 4).