JPH11226722A - Composite roll for rolling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite roll for rolling, in which the residual stress developed between a hard ring and a roll main body is mitigated and the hard ring and the roll main body are engaged in the stable state at the time of producing the roll. SOLUTION: In the composite roll for rolling, in which the hard ring 12 is inserted with molten metal and the molten metal to form the roll main body is solidified, in the hard ring 12, an engaging members 14 composed of a material having smaller deforming resistance than those of the hard ring and the inserting metal, are arranged at the part which is inserted with the roll body. The engaging members 14 are engaged with the inserted roll body and the hardring 12 is made to be integrally rotatable to the roll body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a steel wire rod, a steel bar,
The present invention relates to a composite roll used for rolling section steel and the like.

[0002]

2. Description of the Related Art As shown in FIG. 9, a roll (20) used for rolling wires, bars and the like is provided with a wear-resistant 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
(10) is appropriately machined and finished to a desired shape and dimensions.

Since it is necessary to rotate the roll body and the hard ring integrally, the roll body and the hard ring are fixed by welding a cast-in metal and a cemented carbide. However, since the as-cast metal has a higher coefficient of thermal expansion than the cemented carbide, the difference in thermal contraction in the cooling process in the casting process causes tensile residual stress in the as-cast 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 filed a composite roll in which a hard ring is cast-solidified with a molten metal adjusted to a temperature at which the cemented carbide is not welded. Previously suggested. Since the roll body and the hard ring are not welded, in order to prevent idle rotation between the roll body and the hard ring, a projection is formed on the side surface of the hard ring to engage with the roll body, and the projection is engaged with the roll body. To be able to rotate together. The hard ring is manufactured by sintering a super-hard metal, and the engaging projection is formed integrally during sintering, or formed by machining after sintering.

[0005] However, since the cemented carbide material is hard and brittle, a load or impact is applied to the engagement projections from the roll body and the hard ring during machining after sintering or during rotation or stop of the composite roll. In some cases, the engaging projection was chipped or cracked, resulting in insufficient engagement between the roll body and the hard ring.

SUMMARY OF THE INVENTION An object of the present invention is to provide a rolling composite roll in which a residual stress generated between a hard ring and a roll body is reduced, and the hard ring and the roll body are engaged in a stable state. is there.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention relates to a composite roll for rolling, in which a hard ring (12) is wrapped with molten metal, and the molten metal is solidified to form a roll body (10). The ring (12) is provided with an engaging member (14) made of a material having a smaller deformation resistance than the hard ring and the cast-in metal in a portion to be cast in the roll body (10),
(14) is engaged with the rolled-up roll body (10) so that the hard ring (12) can rotate integrally with the roll body (10). "Deformation resistance" refers to the difficulty of material deformation, whether thermal or mechanical. Therefore, "a material having a smaller deformation resistance than a hard ring and a stuffed metal" means a material that is more easily deformed than a hard ring and a stuffed metal, and more specifically, than a hard ring and a stuffed metal. It means that the material has low proof stress, low tensile strength, or low hardness. It does not matter whether welding is performed between the hard ring (12) and the engaging member (14) and between the cast metal and the engaging member (14).

It is desirable that no welding is performed between the roll body (10) and the hard ring (12). This is to prevent a residual stress from being generated due to a volume change when the cast-in metal is cooled. Therefore, the temperature of the as-cast metal is adjusted to a temperature at which the molten metal does not weld to the hard ring.
The engagement member (14) generates thermal stress due to a difference in thermal expansion between the hard ring (12) and the cast-in metal, but as described above, the engagement member (14) is Since a material having a smaller deformation resistance than a metal is used, the thermal stress is alleviated by plastic deformation of the engagement member (14), and no large residual stress remains.

The engaging member (14) may be provided on a portion where the hard ring (12) is cast into the roll body (10), and is provided on one side surface or both side surfaces of the hard ring (12). Engagement member
The shape of (14) is not particularly limited as long as it can be engaged with the roll body (10). Examples of the shape of the engagement member (14) include a shape protruding from the hard ring (for example, a protrusion, a ridge, or the like). The method of attaching the engagement member (14) to the hard ring (12) is not particularly limited. As a mounting method, for example, clearance fit, shrink fit,
Welding and the like can be mentioned. Alternatively, the engaging member may be preliminarily metallurgically bonded (welded) when the hard ring is manufactured (melted).

[0010]

[Operation and Effect] Since the roll body (10) of the present invention is not welded to the hard ring (12),
Almost no stress remains during roll production. Further, an engagement member (14) which is a contact point between the hard ring (12) and the roll body (10)
When a large thermal stress is applied, the plastic ring is plastically deformed and the stress is relieved, so that little residual stress is generated in the hard ring and the roll body. Therefore, there is no fear that cracks will be generated due to residual stress during subsequent machining or use. Further, since the engaging member (14) is formed of a material having a smaller deformation resistance than the hard ring (12) and the cast-in metal, when starting rotation of the composite roll (20), rotation stop, etc.
Even when the engaging member (14) receives a large mechanical stress such as a load or an impact from the roll body (10) and the hard ring (12), the engaging member (14) may be elastically or plastically deformed. Because these loads and shocks can be absorbed by the
The chip (14) is not easily chipped or cracked, and the engagement between the roll body (10) and the hard ring (12) does not become insufficient.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The hard ring (12) is preferably formed of a high-speed cast iron material in view of machinability.
As shown in FIG. 5 to FIG. As this kind of high-speed cast iron material, C: 2.0-5.0% by weight, S:
i: 0.2 to 2.0%, Mn: 0.2 to 1.5%, Cr:
4.0-15.0%, 2Mo + W: 5.0-30.0%,
V: 7.0 to 20.0%, 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.
1% or less, S: 0.1% or less. The hard ring (12) can of course be made of a material such as a cemented carbide, cermet, ceramics, etc., in addition to the high-speed cast iron material. In the case of producing a hard ring using a high-speed cast iron material, a stationary 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 addition, when it is necessary to provide a groove, a hole, or the like for mounting the engagement member described below,
The hard ring cut to a predetermined width may be appropriately machined.

The cast-in metal which is to be the roll body (10) is preferably formed from ductile cast iron. As ductile cast iron, C: 2.5 to 4.0% (% by weight, hereinafter the same);
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: 0.0
2 to 0.1%, with the balance substantially consisting of Fe, or, if necessary, further containing at least one of W, V, and Nb in a total of 4% or less. .

The engaging member (14) is made of a hard ring (12) and a material having a lower deformation resistance than the cast-in metal (a material having a low hardness, a material having a low tensile strength, or a material having a low proof stress). (12) is provided at a portion to be cast into the roll body (10). Even when a high-speed cast iron material is used as the hard ring (12), its hardness is usually about HS (Shore hardness) of about 70 or more, and the tensile strength is about 500 MPa or more. The required hardness as a rolling roll is usually about HS
35 or more, and the tensile strength is about 350 MPa or more. Therefore, the material constituting the engaging member (14) is lower in hardness and lower in tensile strength or proof stress than the hard ring and the cast-in metal, so that the content of C is about 0.8 or less,
Preferably less than about 0.5%, more preferably about 0.25%
The following steel materials (for example, mild steel materials, structural alloy steels, etc.) are used.

The engaging member (14) preferably has a shape protruding from the hard ring (12).
As shown in FIGS. 1 and 2, a plurality of bottomed holes (16) are formed in the side surface of the hard ring, and each of the rod-shaped engagement members (14) is provided so that there is a slight gap in the bottomed hole (16). ), Fig. 3
As shown in the figure, holes (1) penetrate the hard ring (12) in the width direction.
7), an example in which a rod-shaped engaging member (14) longer than the width of the hard ring is fitted into the through hole (17) such that both ends protrude from the side surface of the hard ring (12). Can be mentioned. As another embodiment, as shown in FIGS. 4 and 5, an annular thin plate provided with a recess (18) on the peripheral surface is formed by an engaging member.
The example used as (14) can be mentioned. The engagement member
(14) has a plurality of pins (19) protruding on one surface of the annular thin plate, and a bottomed hole (16) opened at a position corresponding to the annular ring (12).
The pin (19) is fitted to the boss.

The hard ring to which the engaging member is attached is shown in FIG.
And cast into a cast iron melt that becomes a roll body. The mold is a three-stage mold, as shown in FIG.
Sand molds (36) and (37) are provided on the upper and lower parts of (34), and the sand mold on the lower side
A feeder (38) for supplying a molten cast iron (32) communicates with (37). On the inner circumference of the assembled mold (34), a hard ring (1
Recesses (39) for receiving the outer peripheral portion of (2) are formed at two locations in the vertical direction. After the hard ring (12) is fitted into the recess (39) of the mold (34), a molten cast iron of a predetermined component is supplied from the feeder (38). It is desirable that the hard ring (12) be preheated to about 50 to 100 ° C. in order to prevent cracking during casting of the molten metal. If the preheating temperature is too high, the hard ring
(12) and the cast-in metal may be welded. The molten cast iron (32) is adjusted to a temperature at which it does not fuse with the hard ring (12) and the engaging member (14), and solidifies in a state in which the hard ring (12) to which the engaging member (14) is attached is wrapped and rolled. A body (10) is formed. After the solidification is completed, the mold (34) 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. However, in the heat treatment, it is desirable to use an atmosphere control furnace or a vacuum heat treatment furnace to prevent oxidation of the interface between the hard ring (12) and the cast-in metal.

FIG. 8 is an enlarged sectional view of the periphery of the engaging member (14) of the composite roll (20) produced. Roll body (1
0) is not welded to the hard ring (12), and the engagement member (14)
Is engaged with the hard ring (12) by the roll body (10).
And the hard ring (12) can rotate integrally. Since the roll body is not welded to the hard ring, no residual stress occurs. The stress generated around the engagement member (14) is reduced by plastic deformation. For example, in the case of a hard ring (12) in which a rod-shaped projection shown in FIGS. 2 and 3 is formed as an engagement member (14), the roll body (10) engages with the engagement member (14) wrapped. I do. When the recess (18) is provided as shown in FIG. 5, the molten metal flows into the recess (18) and the roll body
(10) is engaged with the recess (18).

[0017]

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. Based on the weight of the hard ring , C: 3.65%, Si: 0.62%, Mn:
0.70%, P: 0.027%, S: 0.015%, C
r: 10.6%, Mo: 4.48%, W: 5.17%,
V: A high-speed cast iron material consisting of 10.8% and the balance substantially consisting of Fe was used. The molten metal of the high-speed steel is cast by a static casting method, and has an outer diameter of 375 mm, an inner diameter of 210 mm and a width of 270 mm.
mm, a shrinkage cavity portion of the obtained tube was cut to have an outer diameter of 375 mm, an inner diameter of 210 mm, and a width of 200 mm, and subjected to a softening heat treatment at a temperature of 750 ° C., and then divided into two in the width direction. Further, the side and inner surfaces were machined to produce two hard rings (12) having an outer diameter of 375 mm, an inner diameter of 215 mm and a width of 95 mm. On one side of each of the manufactured hard rings (12), a diameter of 250 mm centered on the center of the ring.
Nine bottomed holes (16) having a diameter of 5 mm and a depth of 15 mm for attaching an engagement member were formed at regular intervals on the virtual circle of (1).

A rod member made of carbon steel (S10C) having a diameter of 5 mm and a length of 25 mm of an engaging member is prepared, and a bottomed hole (1) for attaching the engaging member of the hard ring (12) is prepared.
6) Installed by loose fit.

[0019] At Ingredient Weight% of insert casting metal (roll body), C: 3.41%, Si : 2.25%, Mn:
0.41%, P: 0.032%, S: 0.016%, N
i: 0.45%, Cr: 0.21%, Mo: 0.10%,
Ductile cast iron consisting of 0.05% Mg and the balance substantially Fe was used.

Preparation of Composite Roll A pair of hard rings (12) and (12) preheated to 55 ° C. are placed in a mold with the surface on which the engaging member (14) is attached facing upward.
(34) was inserted into the recesses (39) and (39), and the molten ductile cast iron of the above component was cast at a temperature of 1380 ° C. to produce a composite roll (20) having a solidified portion as a roll body.

Heat treatment of composite roll The obtained composite roll (20) is treated in an inert gas atmosphere for 98 hours.
After heating and holding at a temperature of 0 ° C., 300 to 400 (° C. /
H), quenching was performed at a cooling rate of 550 ° C., and tempering was further performed three times at a temperature of 550 ° C. for 10 hours.

[0022] by machining the outer diameter portion of the final mechanical finishing the resulting composite roll (20),
A composite roll having an outer diameter of 360 mm and a shaft length of 650 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), a hard ring (12) and an engagement member (1).
4) and cut and observed, the roll body (10),
It was not welded to either the hard ring (12) or the engaging member (14). Further, the hard ring (12) was supported so as to be integrally rotatable with the roll body (10) by the engagement between the engagement member (14) and the roll body (10). When the hardness of the hard ring, the roll body, and the engagement member were measured, the hard ring had a hardness of HS85 and a tensile strength of 730 MPa, and the roll body had a hardness of HS40 and a proof stress (0.2% proof stress) of 420 M.
Pa, the engagement member has a hardness of HS20, and the yield point is 20.
It was 0 MPa.

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 perspective view of a hard ring according to the present invention.

FIG. 2 is a cross-sectional view of the hard ring of FIG.

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

FIG. 4 is a perspective view showing another further embodiment of the hard ring of the present invention.

FIG. 5 is a sectional view of the hard ring of FIG. 4;

FIG. 6 is an explanatory diagram of a mold for producing a composite roll.

FIG. 7 is a sectional view of the composite roll of the present invention.

FIG. 8 is a cross-sectional view showing an engagement state between an engagement member and a roll body.

FIG. 9 is a cross-sectional view of a conventional composite roll.

[Explanation of symbols]

 (10) Roll body (12) Hard ring (14) Engagement member (20) Composite roll

Claims (3)

[Claims] 1. A rolling composite roll in which a hard ring (12) is wrapped with molten metal and solidified to form a roll body (10), wherein the hard ring (12) is cast around by the roll body (10). An engaging member (14) made of a material having less deformation resistance than the hard ring and the cast-in metal is provided at the portion, and the engaging member (14) is engaged with the rolled-up roll body (10). Together
A composite roll for rolling, characterized in that the hard ring (12) can be rotated integrally with the roll body (10). 2. The rolling composite roll according to claim 1, wherein the engaging member is provided on a side surface of the hard ring. 3. The rolling composite roll according to claim 1, wherein the engagement member is formed of a steel material having a C content of 0.8% by weight or less.