JP2000117310A - Composite roll for rolling, and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the operation in a condition where a hard ring is stably engaged with a roll body by providing a buffer layer to mitigate the stress to be generated between the hard ring and the roll body during the rolling between the hard ring and the roll body to prevent generation of the residual stress between the hard ring and the roll body. SOLUTION: A roll body 10 is engaged with a hard ring 12 on a side surface and/or an inner circumferential surface of which a stepped engagement part 14 is formed in an integratedly rotatable manner in a condition where a buffer layer 16 to mitigate the stress to be generated between the hard ring 12 and the roll body 10 during the rolling is interposed. A composite roll 20 for rolling can be manufactured by providing the buffer layer 16 on a surface of the hard ring 12 with the engagement part 14 formed thereon, the hard ring 12 provided with the buffer layer 16 is fixed to a mold, a molten metal is poured in the mold, and the molten metal is solidified so as to engage he molten metal with the engagement part 14 of the hard ring 12 with the buffer layer 16 interposed therebetween.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As shown in FIG. 5, a roll (20) used for rolling wires, bars and the like is provided on the outer periphery of a roll body (10) of ductile cast iron or graphite steel having excellent toughness. Ring made of hard metal with excellent heat resistance
There is a composite structure equipped with (12). In this method, a hard ring made of cemented carbide is cast and solidified with a melt of ductile cast iron or graphite steel, and the solidified portion forms a roll body (10) .After the cast solidification, the hard ring (12) and the roll body are formed.
(10) is appropriately machined and finished to a desired shape and dimensions.

[0003] Since the roll body (10) and the hard ring (12) need to be rotated integrally, the roll body and the hard ring are fixed by welding a cast-in metal and a cemented carbide.
However, since the cast-in metal has a larger coefficient of thermal expansion than the cemented carbide, thermal contraction in the cooling process in the casting process causes tensile residual stress in the cast-in metal and compressive residual stress in the cemented carbide ring. Therefore, when a large impact load acts on the carbide ring during machining or rolling, cracks are likely to occur at the interface between the carbide ring and the cast-in metal.

[0004]

In order to prevent the occurrence of such residual stress, the applicant has previously sunk a hard ring (12) with a molten metal adjusted to a temperature that does not fuse with a cemented carbide. A solidified composite roll (20) was proposed. Since the roll body (10) and the hard ring (12) are not welded, in order to prevent the roll body (10) and the hard ring (12) from idling, as shown in FIG. A concave engaging portion (14) is formed on the side surface, and the engaging portion (14) is
0) so as to be integrally rotatable.

However, the hard ring engagement portion (14)
Is in direct contact with the roll body (10), so the roll body (10) and the hard ring (1
When 2) is thermally expanded, a large stress is applied to the engaging portion (14), and the stress remains when the temperature is lowered. As a result, the engagement portion (14) may be broken or broken, and the engagement between the roll body (10) and the hard ring (12) may be insufficient.

SUMMARY OF THE INVENTION An object of the present invention is to provide a composite roll for rolling which can prevent the occurrence of residual stress between a hard ring and a roll main body and can ensure operation in a stable engagement state between the hard ring and the roll main body. is there.

[0007]

In order to solve the above-mentioned problems, a composite roll for rolling (20) of the present invention comprises a roll body (10).
And a hard ring (12) having a step-shaped engaging portion (14) formed on a side surface and / or an inner peripheral surface thereof.
It engages with a buffer layer (16) that relieves the stress generated between 2) and the roll body (10) interposed, and can be integrally rotated. The composite roll for rolling (20) of the present invention has a buffer layer (16) on the surface of the hard ring (12) on which the engaging portion (14) is formed.
Is provided, and the hard ring (12) provided with the buffer layer (16) is fixed to a mold, and molten metal is poured into the mold, and the molten metal is buffered.
It can be manufactured by solidifying the molten metal so as to engage with the engaging portion (14) of the hard ring (12) with the (16) interposed. The buffer layer (16) may be provided after the hard ring (12) is fixed to the mold.

It is sufficient that the buffer layer (16) is provided at least on the engaging portion (14) of the hard ring (12) in order to prevent the damage of the engaging portion (14). Alternatively, the hard ring (12) may be provided on the entire surface of the roll body (10). As a material for forming the buffer layer (16), a graphite-based material is used.
(E.g., 10 to 20% by weight of a carbon-based material, with the balance being water).

The thickness of the buffer layer (16) can be appropriately adjusted according to various conditions such as the difference in thermal expansion between the roll body (10) and the hard ring (12), the thickness of the hard ring (12), and the like. Desirably, 0.
1 to 2.0 mm is appropriate, and 0.2 to 0.5 mm.
mm. The buffer layer (16) is 0.1 mm
If it is thinner, the effect of the buffer layer (16) may not be sufficiently exerted. Conversely, if the buffer layer (16) is thicker than 2.0 mm,
The engagement between the roll body (10) and the hard ring (12) may be insufficient.

[0010]

[Operation and Effect] The buffer layer (16) is provided so that the roll body (10) and the hard ring (12) do not come into direct contact with each other.
0) and the stress caused by the expansion of the hard ring (12) are alleviated, and the generation of residual stress is prevented. Therefore, almost no stress acts between the roll body (10) and the hard ring (12), especially between the roll body (10) and the engaging portion (14) of the hard ring (12). Breakage and breakage due to thermal expansion can be prevented, and the engagement between the roll body (10) and the hard ring (12) does not become insufficient.

As the thickness of the hard ring (12) increases, the stress due to the difference in thermal expansion between the roll body and the hard ring (12) increases. However, according to the present invention, due to the presence of the buffer layer (16), the roll body ( Since little stress is generated between the hard ring (12) and the hard ring (12), it is particularly suitable for the thick hard ring (12).

[0012]

Embodiments of the present invention will be described below. The hard ring (12) is preferably formed of a high-speed cast iron material from the viewpoint of machinability, and is formed in an annular shape as shown in FIGS. As this type of high-speed cast iron material, C: 1.6 to 5.0% and Si: 0.2% by weight.
2.0%, Mn: 0.2-1.5%, Cr: 4.0-1
5.0%, Mo + W: 5.0-30.0%, V: 4.5-2
0.0%, with the balance substantially consisting of Fe and unavoidably mixed impurities (eg, P, S, etc.). P and S are inevitably mixed in from the raw materials, but are preferably as small as possible because they make the material brittle. P: 0.1% or less,
S: 0.1% or less is preferable. The hard ring (1
2) can be formed from materials such as cemented carbide, cermet, and ceramics in addition to the high-speed cast iron material.

When producing a hard ring using a high-speed cast iron material, a static casting method is usually used. In the stationary casting method, a molten metal is poured into an annular space formed between a mold constituting a main mold and a sand mold (not shown) constituting a core, and casting is performed. It can be made by cutting to dimensions. In this case, the engaging portion may be appropriately machined on the hard ring cut to a predetermined width. The engaging portion (14) may be formed integrally when the hard ring (12) is cast.

As the engaging portion (14), a concave shape (18) as shown in FIG. 2 and a projection shape (19) as shown in FIG. 3 can be exemplified. The shape of the engaging portion (14) is not limited to these shapes as long as the roll body (10) and the hard ring (12) can be integrally rotatably engaged. Also,
In the figure, the engaging portions (14) are provided on both side surfaces of the hard ring (12), but may be provided on only one surface or on the inner peripheral surface of the hard ring.

As shown in FIGS. 2 and 3, a buffer layer (16) is formed on the surface of the hard ring (12) provided with the engaging portions (14).
The buffer layer (16) can be formed by applying a graphite-based material, generally called a coating mold, to the surface of the hard ring (12). The thickness of the buffer layer (16) is suitably from 0.1 to 2.0 mm, and preferably from 0.2 to 0.5 mm.
The buffer layer (16) is desirably formed on the entire portion where the hard ring (12) is cast into the roll body (10), but may be formed on at least the surface of the engagement portion (14).

The hard ring (12) on which the buffer layer (16) is formed,
It is fixed to a mold shown in FIG. 4 and cast into a molten cast iron to be a roll body (10). As shown in FIG. 4, sand molds (36) and (37) are provided above and below a three-stage mold (34), and the lower sand mold (37) is supplied with molten cast iron (32). The hot water (38) is in communication. On the inner circumference of the assembled molds (34) and (35),
A recess (39) for receiving the outer periphery of the hard ring (12) is formed. After the hard ring (12) is fitted into the recess (39) of the mold (34) (35), a cast iron melt of a predetermined component is supplied from the feeder (38). The hard ring (12) is desirably preheated to about 100 to 700 ° C. in order to prevent cracking during casting of the molten metal. The molten cast iron (32) is adjusted to a temperature at which it does not fuse with the hard ring (12), and solidifies while surrounding the hard ring (12) to form a roll body (10). At this time,
(14) engages with the roll body (10) via the buffer layer (16). After the solidification is completed, the molds (34) and (35) and the sand molds (36) and (37) are removed to produce the composite roll for rolling (20) shown in FIG. If necessary, after appropriate heat treatment,
The roll body (10) and the hard ring (12) are appropriately machined and finished to a desired shape and dimensions.

FIG. 1 is an enlarged sectional view of the periphery of the engaging portion (14) of the composite roll (20) thus produced.
The roll body (10) is not in direct contact with the hard ring (12), and the engaging portion (14) has a buffer body (16) through the roll body (1).
0) and can rotate integrally. For example, when a recess (18) is provided as the engaging portion (14) as shown in FIG. 2, the molten metal flows into the recess, and the roll body (10) is recessed (18) through the buffer layer (16). )
(See FIG. 1). Further, in the case of the hard ring (12) in which the projection (19) shown in FIG. 3 is formed as the engaging portion (14), the roll body engages with the engaging portion wrapped around the buffer layer (FIG. Not shown).

The buffer layer (16) is interposed between the roll body (10) and the hard ring so that the roll body (10) and the hard ring do not come into direct contact. When heated and expanded, it relaxes its stress,
Prevent the generation of residual stress. For this reason, the roll body (10)
Hardly any stress acts between the metal ring and the hard ring (12), especially between the roll body (10) and the engaging portion (14) of the hard ring (12), preventing breakage and breakage due to thermal expansion. it can. Therefore, the engagement between the roll body (10) and the hard ring (12) does not become insufficient.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific example of the production of the composite roll for rolling (20) of the present invention will be described. In terms of the weight of the hard ring , C: 1.82%, Si: 0.92%, Mn:
0.76%, P: 0.04%, S: 0.02%, Cr: 6.0
02%, Mo: 2.08%, W: 4.06%, V: 5.5
%, The balance being a high-speed cast iron material consisting essentially of Fe. The molten metal of the high-speed cast iron material is cast by a static casting method to cast a tubular body having an outer diameter of 350 mm x an inner diameter of 210 mm x a width of 200 mm.
0 mm x inner diameter 210 mm x width 150 mm, 750
After softening heat treatment at a temperature of ° C, the side and inner surfaces are machined to obtain an outer diameter of 330 mm, an inner diameter of 230 mm, and a width of 13 mm.
A 0 mm hard ring (12) was made. On both sides of the manufactured hard ring (12), a diameter 28 centered on the center of the ring is provided.
A 20 mm diameter x 5 mm deep dent on a 0 mm virtual circle
Eight (18) were opened at equal intervals to form an engaging portion (14).

On the surface of the hard ring (12) on which the buffer layer engaging portion (14) is formed, a graphite-based material (10 to 20% by weight of a carbon-based material, the remaining moisture) having a thickness of 0.2 to 0.2. It was applied so as to have a thickness of 3 mm to form a buffer layer (16).

[0021] At Ingredient Weight% of insert casting metal (roll body), C: 3.35%, Si : 2.28%, Mn:
0.51%, Ni: 0.64%, Cr: 0.23%, M
g: Ductile cast iron consisting of 0.05% and the balance substantially Fe.

Preparation of Composite Roll The hard ring (12) preheated to 120 ° C. was placed in the recess (3) of the mold (34).
9) The composite roll (20) having the solidified portion as the roll body (10) was produced by casting the molten ductile cast iron of the above component at a temperature of 1300 ° C. In addition, at the time of casting operation, the molten metal of about 1.5 times the required molten metal is supplied and the upper sand mold
It was discharged from the discharge port provided in (36) to replace the molten metal.

Heat treatment of composite roll The obtained composite roll (20) is heated and maintained at a temperature of 950 ° C., quenched at a cooling rate of 300 to 400 (° C./H), and further at a temperature of 550 ° C. for 10 hours. Tempering treatment was performed three times.

[0024] by machining the outer diameter portion of the final mechanical finishing the resulting composite roll (20),
A composite roll having an outer diameter of 330 mm and a shaft length of 500 mm was produced.

After the final mechanical finishing, when the surface condition of the hard ring (12) was examined by an ultrasonic flaw detection test, no cracks or the like were found. In addition, composite rolls (2
(0) was cut and observed, between the roll body (10) and the hard ring (12), a buffer layer (16) was interposed, respectively.
The roll body (10) was not in direct contact with the hard ring (12). Further, the hard ring (12) and the roll body (10) were engaged with each other via the buffer layer (16) at the engaging portion (14), and were supported so as to be integrally rotatable.

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 appended 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 sectional view of a composite roll for rolling according to the present invention.

FIG. 2 is a sectional view of a hard ring according to the present invention.

FIG. 3 is a sectional view showing another embodiment of the hard ring of the present invention.

FIG. 4 is an explanatory view of a mold for producing a composite roll for rolling.

FIG. 5 is a sectional view of a conventional composite roll for rolling.

[Explanation of symbols]

 (10) Roll body (12) Hard ring (14) Engagement part (16) Buffer layer (20) Composite roll for rolling

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroaki Katayama 64 Nishimujima-cho, Amagasaki City, Hyogo Prefecture F-term in Kubota Amagasaki Plant (reference) 4E016 AA04 AA05 BA10 DA03 DA18 FA03

Claims (4)

[Claims] A hard ring (12) having a step-shaped engaging portion (14) formed on a side surface and / or an inner peripheral surface is wrapped with molten metal, and is engaged with the engaging portion (14) of the hard ring (12). The molten metal is solidified so that it fits together, and the solidified part of the molten metal is used as the roll body (10),
In a composite roll for rolling in which the roll body (10) and the hard ring (12) can be integrally rotated, a hard ring (12) is provided between the hard ring (12) and the roll body (10) when rolling is used. A composite roll for rolling, comprising a buffer layer (16) for relaxing stress generated between the roll and the roll body (10). 2. The buffer layer (16) comprises at least a hard ring (1).
2. The composite roll for rolling according to claim 1, wherein the composite roll is provided in the engaging portion (14) of (2). 3. The thickness of the buffer layer (16) is 0.1 to 2.0 mm.
The composite roll for rolling according to claim 1, which is: 4. A hard ring (12) having a step-shaped engaging portion (14) formed on a side surface and / or an inner peripheral surface is fixed to a mold, and molten metal is poured into the mold to form the hard ring (12). The molten metal is solidified so as to engage with the engaging portion (14), and the solidified portion of the molten metal is formed as the roll body (10), and the roll body (10) and the hard ring are formed.
(12) and a method for producing a composite roll for rolling, wherein the roll body (1) is provided on the surface of the hard ring (12) when rolling is used.
A method for manufacturing a composite roll for rolling, characterized in that a buffer layer (16) for relaxing stress generated between a hard ring (12) and a hard ring (12) is formed.