JP2000271729A - Composite roll for rolling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite roll for rolling for preventing the generation of residual stress of a hard ring and the main body of roll and securing operation with of the hard ring and the main body of roll stably engaged. SOLUTION: In the composite roll for rolling in which the hard ring 12 on the side face and/or inner peripheral face of which a step-shaped engaging parts 14 are formed is wrapped with a molten metal of an insert metal, the insert metal is solidified so as to engage with the engaging parts 14 of the hard ring 12, the solidified parts of the insert metal is taken as the main body 10 of roll and the main body 10 of roll and hard ring 12 are made so as to be integrally rotatable, in order to reduce the stress generated between the hard ring 12 and the main body 10 of roll at the time of manufacturing the roll, a buffer layer 16 formed by melt-spraying or plating the metal having thermal expansion coefficient larger than that of the inset metal is provided on the face wrapped with the insert metal.

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. There is a composite structure in which a hard ring (12) formed of a cemented carbide or a high-speed cast iron material having excellent properties is formed. In this method, a hard ring is cast and solidified with a molten cast metal such as ductile cast iron or graphite steel to solidify a solidified portion with a roll body (10). (10) is appropriately machined and finished to a desired shape and dimensions.

[0003] Since the roll body (10) and the hard ring (12) must be rotated integrally, the roll body and the hard ring are fixed by welding an as-cast metal and a cemented carbide or high-speed cast iron material. . However, the coefficient of thermal expansion of cemented carbide is about 6 × 10 ⁻⁶ / ° C., and the coefficient of thermal expansion of high-speed cast iron material is about 1
In contrast to 0 × 10 ⁻⁶ / ° C., the coefficient of thermal expansion of the as-cast metal is as large as about 12 × 10 ⁻⁶ / ° C., and the thermal shrinkage in the cooling process in the casting process causes tensile residual stress in the as-cast metal. Compressive residual stress is generated in the hard ring. therefore,
When a large impact load acts on the hard ring during machining or rolling, cracks are likely to occur at the interface between the hard ring and the as-cast metal.

[0004]

In order to prevent the occurrence of such residual stress, the applicant has previously provided a hard ring (1).
2) Hard ring with molten metal adjusted to a temperature that does not weld
A composite roll (20) obtained by casting and solidifying (12) 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 engaged with the roll body (10) 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, the rolling composite roll (20) of the present invention has a step-shaped engaging portion (14) formed on a side surface and / or an inner peripheral surface. Hard ring
(12) is wrapped with a stuffed metal melt, and the stuffed metal is solidified so as to engage with the engaging portion (14) of the hard ring (12),
The solidified part of the cast-in metal is used as the roll body (10),
In a rolling composite roll in which the roll body (10) and the hard ring (12) can be integrally rotated, in order to reduce the stress generated between the hard ring (12) and the roll body (10) during roll production. On the hard ring (12), a buffer layer (16) formed by spraying or plating a metal having a higher coefficient of thermal expansion than the cast-in metal on the surface to be cast by the cast-in metal.
Is provided.

[0008] The rolling composite roll (20) of the present invention comprises an engaging portion.
A buffer layer (16) is formed by spraying or plating a metal having a higher coefficient of thermal expansion than the cast-in metal on the surface of the hard ring (12) formed with (14), and the buffer layer (16) The provided hard ring (12) is fixed to a mold, a cast-in metal is poured into the mold, and the cast metal is engaged with the engagement portion of the hard ring (12) with the buffer layer (16) interposed. It can be made by solidifying to engage with 14).

The buffer layer (16) formed on the hard ring (12)
It is sufficient to provide at least the engaging part (14) with the roll body (10) in order to prevent the damage of the engaging part (14),
If necessary, it may be provided on the entire surface to be inserted by the insert metal. When ductile cast iron is used as a cast-in metal, the coefficient of thermal expansion of ductile cast iron is about 12 ×
Because it is 10 ^-6 / ° C., as a material for forming the buffer layer (16), can be thermal expansion coefficient illustrate approximately 16.8 × 10 ^-6 / ℃ copper.

The thickness of the buffer layer (16) may be appropriately adjusted according to various conditions such as the difference in thermal expansion between the cast-in metal and the hard ring (12), the thickness of the hard ring (12), and the like. Preferably,
When the body length of the roll body (10) is L and the step length of the engaging portion (14) is d, the thickness t of the buffer layer (16) is 0.001L.
It is formed so that ≦ t ≦ 0.6d. If the thickness t of the buffer layer 16 is smaller than 0.001 L, the effect of the buffer layer 16 may not be sufficiently exerted.
Is thicker than 0.6d, the roll body (10) and the hard ring
The engagement with (12) may be insufficient.

[0011]

[Function and effect] Hard ring (12) formed with buffer layer (16)
Is cast with a cast-in molten metal, the metal of the buffer layer (16) rises in temperature and expands thermally. After the hard ring (12) is cast, when the cast-in metal is solidified, the metal of the thermally expanded buffer layer (16) thermally contracts as the temperature drops. At this time, the buffer layer (1
6) shrinks more than the stuffed metal, so the stress generated between the hard ring (12) when the stuffed metal shrinks is absorbed by the shrinkage of the metal in the buffer layer (16), and the residual stress is small. Become. As a result, cracks in the cast-in metal can be prevented.

Since the composite roll for rolling (20) of the present invention has a small residual stress during the production of the roll, even when used for rolling, the composite roll for roll (20), particularly between the roll body (10) and the hard ring (12), particularly the roll body ( Almost no stress occurs between the engagement portion (14) of the hard ring (12) and the engagement portion (14). Therefore, breakage and breakage due to the generation of these stresses can be prevented. Further, the engagement between the roll body (10) and the hard ring (12) does not become insufficient.

By forming the buffer layer 16 by plating or thermal spraying, the buffer layer 16 can be formed to a desired thickness.
Note that the thickness of the buffer layer (16) is appropriately determined according to the coefficient of thermal expansion of the cast-in metal, the hard ring, and the metal of the buffer layer.

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, the present invention is based on the existence of the buffer layer (16). Since little stress is generated between the hard ring (12) and the hard ring (12), it is particularly suitable for a thick hard ring (12).

[0015]

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 impurities (eg, P, S, etc.) unavoidably mixed. 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 also 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 cast metal is poured into an annular space formed between a mold that forms a main mold and a sand mold (not shown) that forms a core, and is cast. Can be made by appropriately cutting in a width dimension. In this case, the engaging portion may be appropriately machined on the hard ring cut to a predetermined width. The engaging portion (14) is a hard ring (12)
May be integrally formed when casting.

As the shape of the engaging portion (14), a recess (18) as shown in FIG. 2 and a projection (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 spraying or plating a metal having a larger coefficient of thermal expansion than the cast-in metal that becomes the roll body (10) on the surface of the hard ring (12). The buffer layer (16) is preferably formed on the entire portion of the hard ring (12) that is cast into the roll body (10),
What is necessary is just to form on the surface of the engaging part (14) at least. Buffer layer
As shown in FIG. 1, when the roll length of the roll body (10) is L and the step length of the engaging portion (14) is d, as shown in FIG.
The thickness t in 6) is desirably formed such that 0.001L ≦ t ≦ 0.6d.

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, the mold is provided with sand molds (36) and (37) above and below a two-stage mold (34), and supplies molten cast iron (32) to the lower sand mold (37). Hot water outlet (38) is in communication. A recess (39) for receiving the outer periphery of the hard ring (12) is formed on the inner periphery of the assembled molds (34) and (35). After fitting the hard ring (12) into the recess (39) of the mold (34) (35), a molten cast iron of a predetermined component is supplied from the hot water supply port (38). It is desirable that the hard ring (12) be preheated in order to prevent cracking during casting. The cast-in metal melt (32) is adjusted to a temperature at which it does not fuse with the hard ring (12), and is poured into a mold. The metal of the buffer layer (16) is heated and expanded by the poured molten metal. Buffer layer (16)
The coefficient of thermal expansion of the metal is larger than the coefficient of thermal expansion of the as-cast metal, and the shrinkage at the time of temperature decrease is also higher than that of the as-cast metal. As a result, the stress generated between the as-cast metal and the hard ring (12) is reduced. After the solidification is completed, as shown in FIG. 1, the roll composite roll (20) in which the roll body (10) and the hard ring (12) are engaged via the buffer layer (16) is produced. The composite roll for rolling (20), if necessary, is subjected to appropriate heat treatment, then appropriately machined to the roll body (10) and the hard ring (12) to be 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 cast metal flows into the recess and the roll body
(10) is engaged with the recess (18) via the buffer layer (16) (see FIG. 1). Also, the protrusion (19) shown in FIG.
In the case of the hard ring (12) formed as (14), the roll body engages with the engagement portion wrapped around the buffer layer.
(Not shown).

[0021]

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 high-speed cast iron material is cast by static casting to form an outer diameter of 350 mm x an inner diameter of 210 mm x a width of 200 mm.
After the shrink cavity portion of the obtained tube was cut and cut into 350 mm in outer diameter × 210 mm in inner diameter × 150 mm in width and subjected to a softening heat treatment at a temperature of 750 ° C., the side and inner surfaces were machined. Application, outer diameter 330mm x inner diameter 230m
A hard ring (12) having a size of mx 130 mm was prepared. Eight recesses (18) having a diameter of 20 mm and a depth of d: 5 mm are formed at equal intervals on both sides of the produced hard ring (12) on an imaginary circle having a diameter of 280 mm centering on the center of the ring. Joint part (1
4).

Copper was thermally sprayed to a thickness of 1 mm on the surface of the hard ring (12) on which the buffer layer engaging portion (14) was formed to form a buffer layer (16).

C: 3.35%, Si: 2.28%, Mn: by weight of the component of the cast-in metal (roll body)
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 250 ° 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.

Heat treatment of composite roll After heating the obtained composite roll (20) at a temperature of 950 ° C., it is 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.

Finishing Machine Finishing The outer diameter portion of the obtained composite roll (20) is machined,
A composite roll having an outer diameter of 330 mm and a trunk length L 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. This is because, due to the thermal expansion and contraction of the buffer layer (16) at the time of casting, the stress generated at the time of solidification of the as-cast metal was absorbed and reduced. When the composite roll (20) was cut and observed, the roll body (1
0) and the hard ring (12) were integrally rotatably supported via the buffer layer (16).

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 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 section (16) Buffer layer (20) Rolling composite roll

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroaki Katayama 64 Nishimujimajima-cho, Amagasaki-shi, Hyogo F-term in Kubota Amagasaki Plant (reference) 4E016 AA04 AA05 DA03 FA03 FA12 FA13

Claims (4)

[Claims] 1. 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 a cast-in molten metal, and the engaging portion (14) of the hard ring (12) is formed. The solidified portion of the cast-in metal is solidified to engage with the roll body (10) to form a solidified portion of the cast-in metal, and the roll body (10) and the hard ring (12) can be integrally rotated. In the composite roll for rolling, in order to reduce the stress generated between the hard ring (12) and the roll body (10) during roll production, the hard ring (12) has a And a buffering layer (16) formed by thermal spraying or plating a metal having a higher coefficient of thermal expansion than the cast-in metal. 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 rolling composite roll according to claim 1, wherein the buffer layer is formed by spraying or plating copper. 4. The roll length of the roll body (10) is L, the engagement portion (1
When the step length of 4) is d, the thickness t of the buffer layer 16 is
The composite roll for rolling according to any one of claims 1 to 3, wherein is formed so that 0.001L ≦ t ≦ 0.6d.