JP2002224718A - Cemented carbide-made composite roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cemented carbide-made composite roll of a long and large diameter which can be manufactured in a good yield, efficiently and without any cracks and stable rolling capable of suppressing a crack can be carried out even though the roll of the long and large diameter is applied to various kinds of rolling such as cold tandem rolling, hot rough rolling, hot finishing rolling, thick plate rolling, shape steel rolling. SOLUTION: This cemented carbide-made composite roll is made by fittingly fixing a sleeve constituted of an outer layer comprising the cemented carbide by integrating a plurality of cylindrical formed members sintered before-hand and an inner layer comprising the material of a molten-made steel group formed on the inner face of the outer layer to a steel-made shaft center, the sleeve is regulated to be in the range of more than 520 mm and less than 600 mm in length of the sleeve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sleeve constituted by an outer layer made of a cemented carbide and an inner layer made of a steel material formed on the inner surface of the outer layer, which is fitted and fixed to a steel shaft core. A composite roll made of cemented carbide.

[0002]

2. Description of the Related Art Work rolls (hereinafter, referred to as work rolls) incorporated in rolling mills.
Rolls are also abbreviated). In the body that comes into contact with the material to be rolled, it is difficult for the body to be worn, cracked or chipped, the material to be rolled is not easily roughened, the dent is not easily formed, the thermal Performance such as a small crown (convex shape of the roll in the body length direction due to thermal expansion of the roll) is required, but in a commonly used steel roll,
There is a drawback that the above-mentioned performances such as wear resistance and surface roughness resistance are insufficient, and furthermore, the thermal crown is large and there is a limit in improving the control accuracy of the size and shape of the material to be rolled.

[0003] For example, Japanese Patent Application Laid-Open No. 10-5825 discloses an outer layer 11 made of a cemented carbide as shown in FIG. 7 as a roll having excellent performance such as abrasion resistance and surface roughness resistance.
Inner layer 2 made of molten steel material formed on the inner surface of outer layer 11
The cemented carbide composite roll in which the sleeve constituted by the above is fitted and fixed to the steel shaft core 3 is disclosed. JP
The cemented carbide composite roll disclosed in Japanese Patent Application Laid-Open No. 10-5825 has a cross-sectional area of the outer layer 11 in a cross section perpendicular to the rotation axis, in which an inner layer 2 made of a molten steel material is formed on the inner surface of the outer layer 11. When the ratio of the cross-sectional area of the inner layer 2 to the inner layer 2 is 0.7 or less,
By applying a large compressive stress of 100 MPa or more, we are trying to suppress the occurrence of cracks in the outer layer made of cemented carbide, which is hard and has excellent wear resistance, but is weak against impact and tensile stress. Is what you do.

However, when a large-diameter / long-length roll is to be manufactured, in the case of a cemented carbide alloy roll as shown in FIG. In order to form the outer layer 11 made of a cemented carbide of a long integrally formed body by sintering, there is a problem that the dimensional change of the sleeve is large.If the sleeve dimensions are insufficient, the specification of the cemented carbide composite roll is changed. Since it becomes unsatisfactory, it is usually manufactured with a margin so that the sleeve size after sintering is larger than the target size,
After that, it is finished to the target size by grinding.

[0005] For this reason, in a conventional cemented carbide composite roll as shown in FIG.
If an attempt is made to form the outer layer 11 made of cemented carbide having a long length of 600 mm and a sleeve length of 520 mm or longer by sintering, the amount of grinding of the outer layer 11 of the sleeve increases, and the grinding load increases. And the production yield of the cemented carbide (the weight of the outer layer of the sleeve / the amount of the cemented carbide mixed powder charged into the compact) is low.

Further, it is difficult to uniformly sinter the sleeve with a conventional cemented carbide composite roll as shown in FIG. 7, and minute pores are formed in the outer layer 11 of the cemented carbide sleeve. There is room for improvement in the fact that, when subjected to rolling, cracks develop from minute holes generated during sintering, and cracks occur in the outer layer 11 of the sleeve. As a composite roll made of cemented carbide, which solves such a point and significantly reduces the dimensional change after sintering and can produce a large-diameter and long roll, a roll as shown in FIG. No. 10-263627.

A cemented carbide composite roll disclosed in Japanese Patent Application Laid-Open No. Hei 10-263627 includes a sleeve 21 made of a cemented carbide formed by integrating a plurality of cylindrical molded members pre-sintered. When the sleeve 21 is manufactured, a plurality of cylindrical molded members that have been subjected to sintering such as preliminary sintering are subjected to a final sintering process. HIP
Since the sleeve 21 is integrated by processing or the like, the dimensional change of the sleeve 21 when the sleeve 21 is integrated can be greatly reduced.

However, in the cemented carbide composite roll as shown in FIG. 8, when the sleeve 21 is fitted to and fixed to the steel shaft core 3, the shrink fit method (heating the sleeve 21 side to fit) is required. ), Cold fitting method (cooling and fitting the steel shaft core 3 side) or baking and cooling fitting method (heating the sleeve 21 side, cooling the steel shaft core 3 side and fitting) In this case, a tensile stress is applied to the sleeve 21 due to the thermal expansion of the steel shaft core 3 having a low temperature. There is a problem that may occur.

In the case of a cemented carbide composite roll as shown in FIG.
After being fitted and fixed to the steel shaft core 3, the sleeve 21 is still in a state in which a tensile stress is applied, so that cracks are likely to occur during rolling or the molded member is integrated. There is a problem that a crack may occur from the joint 21A.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems in the conventional cemented carbide alloy rolls. , And can be manufactured without cracking, cold tandem rolling, hot rough rolling, hot finishing rolling, plate rolling,
Provided is a long and large-diameter cemented carbide alloy roll that can suppress cracking even when subjected to various types of rolling such as shape steel rolling, has good controllability of the size and shape of the material to be rolled, and is capable of stable rolling. It is in.

[0011]

According to the present invention, there is provided an outer layer made of a cemented carbide formed by integrating a plurality of cylindrical molded members pre-sintered, and a steel system formed on the inner surface of the outer layer. A composite roll made of cemented carbide, which is formed by fixing a sleeve constituted by an inner layer made of a material and fitting and fixing it to a steel shaft core, wherein the sleeve has a length of 520 mm or more and 6000 mm or more.
This is a cemented carbide composite roll characterized by having a diameter of less than mm.

[0012] In the above-mentioned composite roll made of cemented carbide, it is preferable that the number of molded body members is 5 or more and 30 or less.
The above-mentioned cemented carbide composite roll has an outer diameter of 150 mm or more, 800 m
m or less, and applied as a work roll for a cold tandem rolling mill, or with an outer diameter of 500 mm or more and 1500 mm or less, applied as a work roll for a hot rough rolling mill, with an outer diameter of 400 m
m or more, 1400 mm or less, and applied as a work roll for a hot finishing rolling mill, or an outer diameter of 500 mm or more, 1500 mm or less, applied as a work roll for a plate rolling machine, or an outer diameter of 600 mm or more, 2000 mm or less It is preferable to apply it as a work roll for a section steel rolling mill.

[0013]

FIG. 1 is a schematic cross-sectional view in the direction of the rotation axis of a cemented carbide roll according to the present invention. FIG. 2 is a schematic cross-sectional view of the cemented carbide composite roll according to the present invention in a direction perpendicular to the rotation axis. 1 and 2, 1 is an outer layer, 2
Is an inner layer, 3 is a shaft core, and 1A is a joint where a pre-sintered molded body member is integrated.

The cemented carbide composite roll according to the present invention comprises a sleeve composed of an outer layer 1 made of a cemented carbide and an inner layer 2 made of a steel material formed on the inner surface of the outer layer 1, and a steel shaft. It is fitted and fixed to the core. The steel shaft core 3 is formed longer than the length of the sleeve so that bearings can be attached to both ends of the steel shaft core 3, and the sleeve is fitted to the longitudinal center portion of the steel shaft core 3. Fixed together.

In FIG. 1, the outer layer 1 made of a cemented carbide and the inner layer 2 made of a steel material formed on the inner surface of the outer layer 1 are formed to have the same length. Is provided with a steel-based end ring 4. Here, in the present invention, an outer layer 1 made of a cemented carbide formed by integrating a plurality of cylindrical molded members pre-sintered, and a molten steel-based material formed on the inner surface of the outer layer 1 Inner layer 2 made of wood
And the length of the sleeve is set to 520 mm or more and 6000 mm or less.

The cemented carbide of the outer layer 1 is obtained by adding one or more selected from metal powders of Co, Ni, Cr, Ti, etc. to a cemented carbide powder such as WC, TaC, TiC, etc. for 5 to 50 mass%. % Of super hard material mixed powder is sintered, and as the super hard material mixed powder, WC-5 to 50 mass% Co powder is sintered. It is desirable because of its excellent properties and good toughness. Furthermore, this cemented carbide has a coefficient of thermal expansion (coefficient of linear expansion) about half that of conventional materials such as high-speed steel and semi-high-speed steel. As compared with a roll of such a material, the contact arc length between the roll and the material to be rolled is shortened, the contact time associated with the roll rotation during rolling is also shortened, the heat input to the roll is reduced, and the thermal crown is small. There is an advantage that it becomes. If the absolute amount of thermal crown becomes smaller,
This is desirable because the accuracy of controlling the size and shape of the material to be rolled is improved.

The steel material of the inner layer 2 is desirably a smelted material of any of cast steel, forged steel, graphite cast steel, carbon steel and alloyed carbon steel, and will be described below as a smelted steel material. The present invention is not limited to ingots. The shaft core 3 can be prepared by tempering chromium steel, chromium molybdenum steel, or high-speed steel, for example.

Hereinafter, a method of manufacturing a cemented carbide composite roll according to the present invention will be described with reference to FIGS. 3 (a) and 3 (b). FIG. 3A is a perspective view showing a plurality of formed body members 5 used for a sleeve of one cemented carbide composite roll, and FIG. 3B is a plurality of pre-sintered cylindrical formed bodies. Cemented carbide sleeve formed by integrating member 5
FIG. 21 is a cross-sectional view showing a process of forming a sleeve by forming an inner layer 2 made of a molten steel-based material on the inner surface of a sleeve 22.

1 and 2 are denoted by the same reference numerals. The cemented carbide composite roll of the present invention is, for example, filled with powder (preparing a plurality of compacts per roll) → CIP processing → machining → temporary sintering → machining → main sintering / HIP processing ( A plurality of molded members are integrated to create a cemented carbide sleeve 22) → machining → diffusion bonding (joining a steel-based cylindrical inner layer member to the inner surface of the cemented carbide sleeve 22) → fitting It can be manufactured through a process of joining and fixing (fitting and fixing the sleeve to the steel shaft core).

A compact is prepared by mixing a superhard material powder and a metal powder, and filling the resulting mixed powder of the superhard material into a gap between the outer cylinder and the inner cylinder. The obtained hollow molded body is pre-sintered, and if necessary, after pre-sintering,
A hollow cylindrical molded body member 5 as shown in FIG. It is desirable to perform a CIP (cold isostatic pressing) treatment prior to the preliminary sintering, since a high-density hollow molded body member 5 can be obtained.

After the pre-sintering or the pre-sintering obtained in this manner, the machined molded body member 5 is obtained by laminating a plurality of hollow molded body members 5 coaxially and then performing main sintering.・ HI
The cemented carbide sleeve as shown in the left figure of FIG. 3 (b) is integrated by diffusion bonding by P (hot isostatic pressing) treatment.
22 is formed, and a steel-based cylindrical inner layer member is diffusion-bonded to the inner surface of the sleeve to obtain a sleeve as shown in the right diagram of FIG.

The sleeve is further subjected to mechanical processing such as grinding and polishing, if necessary, and then the sleeve is fitted to the shaft core and fixed by a usual method such as shrinkage fitting or cooling shrinkage. CIP molding conditions are, for example, 100 to 300 MP.
It is good to hold for 5-60 minutes at a. As for the condition of the preliminary sintering, it is preferable to keep the temperature at 550 to 800 ° C. for 1 to 3 hours.

The sintering / HIP treatment is performed, for example, in an Ar atmosphere under a pressure condition of 100 to 200 MPa and a sintering condition of 1100 to 1200 MPa.
C., 0.5-2 hours, then 1300-1350 C.
Hold for hours. The sintering / HIP treatment is not limited to the simultaneous treatment, and a pressure treatment may be performed after sintering. For example,
A 50 mm thick cylindrical SCM on the inner surface of the cemented carbide sleeve 22 −
When diffusion bonding of 440 equivalent forged steel is performed under Ar atmosphere,
It is performed by holding at 1200-1300 ° C for 0.5-1 hour.

As described above, in the present invention, a plurality of pre-sintered cylindrical molded members 5 are subjected to the main sintering / HIP
Since the sleeve made of cemented carbide is integrated by processing, the dimensional accuracy of the sleeve after integration can be improved, so the grinding amount can be reduced, the production yield of cemented carbide is good, and the production efficiency is high Well, for example, 600mm in diameter
Thus, it is possible to manufacture a long and large-diameter roll having a sleeve length of 520 mm or more.

On the other hand, as shown in FIG. 7, when the outer layer of a sleeve made of a cemented carbide having a long length is formed by sintering, the amount of grinding of the sleeve after sintering is reduced. Large-diameter rolls with a diameter of, for example, 600 mm and a sleeve length of 520 mm or more. It was difficult to efficiently and economically produce.

Further, in the present invention, since the inner layer made of a smelted steel material is formed on the inner surface of the outer layer made of cemented carbide to form the sleeve, the sleeve 21 made of cemented carbide shown in FIG. As compared with the case where the inner surface of the cemented carbide sleeve 21 does not have a molten steel-based material, it is possible to prevent the sleeve from breaking even at the time of fitting in the manufacturing process and also during rolling operation. .

This is shown in FIG. 5 showing the probability of occurrence of cracks in the outer layer of the sleeve in the present invention, and FIG. 6 showing the probability of occurrence of cracks in the sleeve of the conventional cemented carbide composite roll shown in FIG. As is clear from comparison, as in the present invention, when a plurality of pre-sintered cylindrical molded body members 5 are integrated by a main sintering / HIP process to form a sleeve made of a cemented carbide, cracking occurs. The reason for the low occurrence probability is that the stress in the circumferential direction and the rotation axis direction of the outer layer of the sleeve generated during fitting and rolling becomes compressive stress.

The state in which a compressive stress acts on the outer layer of the sleeve is that the steel-based inner layer member is super-cooled during the cooling process immediately after the diffusion of the steel-based inner layer member to the inner surface of the cemented carbide sleeve. Since the thermal expansion coefficient is larger than that of the hard alloy sleeve, the contraction amount becomes large, and this is caused by the difference in the contraction amount. 5 and 6 show the results of investigation on a roll for a cold tandem rolling mill having an outer diameter of 560 mm, a body length of 1800 mm, and a total length of 3500 mm.

As described above, the cemented carbide composite roll of the present invention has an outer layer made of a cemented carbide constituted by integrating a plurality of cylindrical molded members pre-sintered, and an inner surface of the outer layer. The sleeve, which is made up of the formed inner layer made of molten steel, is fitted and fixed to the shaft core.The length of the sleeve is 520 mm or more and 6000 mm or less. With these rolls, production efficiency and yield can be improved, that is, economical production can be achieved.

Here, the length of the sleeve as described above is
When manufacturing the cemented carbide composite roll of the present invention having a size of 520 mm or more and 6000 mm or less by the above method, the relationship between the number of molded members per roll and the production yield of cemented carbide, and one roll In addition to investigating the number of formed body members per unit and the probability of occurrence of cracks in the outer layer of the sleeve at the time of fitting, the cemented carbide composite roll that could be manufactured without cracking was subjected to rolling, and the outer layer of the sleeve during rolling was cracked. The probability of occurrence was investigated.

In this investigation, the outer diameter was 560 mm and the body length was
The test was performed on a roll for a cold tandem rolling mill having a length of 1800 mm and a length of 3500 mm. The results are shown in FIGS. 4 and 5, respectively. FIG. 4 is a graph showing the relationship between the number of compacts per roll and the production yield of cemented carbide in the invention example;
FIG. 3 is a graph showing the number of molded members per roll, the probability of occurrence of cracks in the outer layer of the sleeve at the time of fitting, and the probability of occurrence of cracks in the outer layer of the sleeve during rolling in the invention example.

In FIG. 4, the production yield of the cemented carbide is determined by dividing the weight of the cemented carbide sleeve by the number of molded articles (plural pieces).
This is a value obtained by dividing by the filling weight of the mixed powder of the super-hard material filled in. The reason for the result shown in FIG. 4 is as follows. If the number of molded members is less than 5, the body length per molded member becomes large, and the thermal shrinkage accompanying cooling immediately after sintering is large, so that a large molded body can be provided with a margin. Since this leads to the production of the member and the shrunk shape is also distorted, the grinding amount in the process of producing the cemented carbide sleeve increases, and the production yield of the cemented carbide deteriorates. In addition, when the number of molded body members exceeds 30, the number of mating surfaces on which the molded body members overlap is increased, and the grinding amount of the cemented carbide sleeve is increased by this amount, and the production of cemented carbide is increased. Yield deteriorates.

Further, from the results shown in FIG. 5, when the number of molded members per roll exceeds 30, the crack generation rate increases. The reason for this is that as the number of superposed surfaces of the molded body members increases, cracks starting therefrom are more likely to occur. Needless to say, if the amount of grinding increases, the grinding time also increases and the production efficiency deteriorates.

As described above, the length of the sleeve is 520 mm or more.
In the cemented carbide composite roll according to the present invention having a diameter of 6000 mm or less, the molded article is formed from the viewpoint of improving the production yield of the cemented carbide and suppressing cracking of the cemented carbide sleeve during fitting and rolling. It is preferable that the number of members is 5 or more and 30 or less. The above-described cemented carbide composite roll of the present invention has an outer diameter of 150 mm or more and 1500 mm or less, and when applied as a work roll for a cold tandem rolling mill, the heat scratch resistance and the surface gloss of the material to be rolled are reduced. When the diameter is 5000mm or more and 1500mm or less and it is applied as a work roll for a hot rough rolling mill, the performance of dimension and shape control by reducing the thermal crown is reduced to an outer diameter of 400mm or more and 1400mm or less. When applied as a roll, dimensions due to thermal crown reduction,
When the shape control performance is set to an outer diameter of 500 mm or more and 1500 mm or less and applied as a work roll for a plate rolling mill, the size and shape control performance by reducing the thermal crown is reduced to an outer diameter of 600 mm or more and 2000 mm or less. When applied as a work roll for a steel rolling mill, the performance of size and shape control by reducing the thermal crown is significantly improved compared to conventional steel rolls, and the performance common to the above applications is abrasion resistance and rough surface resistance. The properties, cracks, chips, and dent resistance (due to the rolling of foreign matter) are preferable because they are significantly improved as compared with conventional steel rolls.

[0035]

EXAMPLES (Example 1) FIGS. 1 and 2 show Invention Example 1.
Production of two rolls for a cold tandem rolling mill with an outer diameter of 560 mm, a body length of 1800 mm, and a total length of 3500 mm as shown in the above, the production yield of cemented carbide when producing a sleeve,
The state of cracking in the outer layer of the sleeve during fitting and the total time required for grinding per roll of cemented carbide were examined.

In Inventive Example 1, six sintered cylindrical members per roll pre-sintered are coaxially superposed, then subjected to sintering and HIP treatment, and integrated to form a cemented carbide sleeve. The cemented carbide sleeve is formed by diffusion bonding a cylindrical inner layer member made of a molten steel material to the inner surface of the cemented carbide sleeve. Two composite rolls were manufactured.

The compact was mixed with a WC powder having an average particle diameter of 3 to 5 μm and a Co metal powder having an average particle diameter of 1 to 2 μm having the composition shown in Table 1 for 2 days using a WC ball as a mixing medium. The mixed powder of the obtained superhard material was filled in a gap between an outer cylinder and an inner cylinder of a double cylindrical rubber mold to prepare a mixture. The outer cylinder made of double cylindrical rubber has an inner diameter of 835mm and a length of 425mm.
The inner cylinder has an outer diameter of 350 mm and a length of 425 mm. Insert a pipe-shaped mandrel with a diameter of 345 mm and a length of 500 mm into the center of the double cylinder and place a rubber mold on a hammer-type filling machine. , A series of processes of filling the mixed powder of the super-hard material in equal amounts, and then pressurizing.

Table 1 shows other detailed conditions. Also,
Table 2 shows the processing conditions for diffusion bonding a cylindrical inner layer member made of a molten steel material to the inner surface of a cemented carbide sleeve.

[0039]

[Table 1]

[0040]

[Table 2]

Inventive Example 2 was the same as Inventive Example 1 except that the number of pre-sintered molded members was four and the length per molded member was as shown in Table 1. In the same manner as in Invention Example 1, the production yield of cemented carbide when producing the sleeve, the state of cracks in the outer layer of the sleeve at the time of fitting, and the time required for grinding per cemented carbide roll Was investigated.

Since the number of molded members used per roll was changed from that of Inventive Example 1, the lengths of the outer cylinder and the inner cylinder were set to 640 mm, and the length of the pipe-shaped mandrel was set appropriately. Filling was performed. As the cemented carbide composite roll of Conventional Example 1, the one having the configuration shown in FIG. 8 was produced under the conditions shown in Table 1, and the production of cemented carbide at the time of producing the sleeve was performed in the same manner as in Invention Example 1. The yield, the state of cracks in the outer layer of the sleeve at the time of fitting, and the total time required for grinding per roll of cemented carbide were examined.

The molded body was produced in the same manner as in Invention Example 1, except that the outer cylinder made of a double cylindrical rubber had an inner diameter of 835 mm, a length of 2800 mm, and an inner cylinder having an outer diameter of 350 mm. A pipe-shaped mandrel having a diameter of 345 mm and an appropriate length was inserted into the center of the double cylinder. As the cemented carbide composite roll of Conventional Example 2, a roll having the configuration shown in FIG. 7 was manufactured under the conditions shown in Table 1.
As in Invention Example 1, the production yield of cemented carbide when producing the sleeve, the state of cracking in the outer layer of the sleeve at the time of fitting, and the total time required for grinding per roll were examined.

The molded article was produced in the same manner as in Invention Example 1, except that the outer cylinder made of a double cylindrical rubber had an inner diameter of 900 mm and a length of 6000 mm, and the inner cylinder had an outer diameter of 219 mm. A pipe-shaped mandrel having a diameter of 219 mm and an appropriate length was inserted into the center of the double cylinder. Table 2 shows the production yield of the cemented carbide at the time of producing the sleeve, the state of cracks in the outer layer of the sleeve at the time of fitting, and the total time required for grinding per roll.

From the results shown in Table 2, the cemented carbide composite rolls of Inventive Examples 1 and 2 did not cause cracks in the outer layer of the sleeve when the sleeve was fitted to the steel core. It was found that the alloy can be subjected to rolling, and that the production yield of cemented carbide can be made better than in the case of Conventional Example 2, and that the number of days required for cutting can be reduced. In the case of Invention Example 1, the number of pre-sintered molded body members was 6
As a result, the production yield of the cemented carbide mixed powder was better than that of Inventive Example 2.

The cemented carbide composite roll of Conventional Example 1 has a low production yield of cemented carbide, requires a long cutting time, and has a problem that the sleeve is cracked at the time of fitting, so that it can be used for rolling. Did not. (Example 2) A composite roll made of cemented carbide having the roll dimensions shown in Table 3 and the members shown in Table 4 having the configuration shown in FIGS. The performance was investigated.

The cemented carbide sleeve shown in Table 4 is
A plurality of pre-sintered compact members shown in Table 5 are integrated by main sintering and HIP processing,
When producing a cemented carbide sleeve, the production yield of cemented carbide was also examined. As a conventional example, the configuration shown in FIG. 7, the roll dimensions shown in Table 3, the cemented carbide composite roll of the members shown in Table 4, the outer layer of the sleeve is formed as an integrally molded body, Further, as comparative examples, rolls having the same roll dimensions as those of the invention examples shown in Table 3 and the roll materials shown in Table 5 were incorporated into the same various rolling mills as the invention examples, and their performances were examined. Incidentally, the cold tandem rolling mill was examined for the fifth stand out of a total of five stands, and the hot finishing rolling mill (also one of the tandem rolling mills) was examined for the first stand and the seventh stand among the seven stands.

Table 5 shows the roll performance of the invention example, the conventional example and the comparative example, and the production yield of cemented carbide at the time of producing the rolls of the invention example and the conventional example.

[0049]

[Table 3]

[0050]

[Table 4]

[0051]

[Table 5]

From the results shown in Table 5, the length of the sleeve was set to 52
It can be seen that the cemented carbide composite roll of the invention example having a thickness of 0 mm or more and 6000 mm or less has a higher production yield of cemented carbide powder than the conventional cemented carbide composite roll. Further, the cemented carbide composite roll of the invention example in which the length of the sleeve is 520 mm or more and 6000 mm or less, when used as a work roll of each rolling mill, the cold semi-high speed and hot high speed roll of the comparative example. More wear resistance,
Since the surface roughness is excellent, the number of rolling limit is large, the crack resistance is excellent, and the thermal crown is small.
It can be seen that the shape of the material to be rolled is better than that of the roll of the comparative example.

[0053]

According to the composite roll made of cemented carbide of the present invention, it is possible to manufacture the composite roll with good yield, efficiently and with reduced cracking even when the roll is long and large.
When subjected to various types of rolling, cracks can be suppressed and stable rolling can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view in the rotation axis direction of a composite roll made of a cemented carbide according to the present invention.

FIG. 2 is a schematic cross-sectional view of a cemented carbide composite roll according to the present invention in a direction perpendicular to the rotation axis.

3A and 3B are diagrams showing a process of manufacturing a sleeve used in the present invention, wherein FIG. 3A is a perspective view and FIG. 3B is a cross-sectional view.

FIG. 4 is a graph showing the relationship between the number of compact members and the production yield of cemented carbide in the inventive example.

FIG. 5 is a graph showing the relationship between the number of molded body members and the probability of occurrence of cracks in the outer layer of the sleeve in the inventive example.

FIG. 6 is a graph showing the relationship between the number of molded body members and the probability of occurrence of cracks in a sleeve in a conventional example.

FIGS. 7A and 7B are views showing a conventional cemented carbide composite roll, in which FIG. 7A is a schematic sectional view in the direction of the rotation axis, and FIG. 7B is a schematic sectional view in the direction perpendicular to the rotation axis.

8A and 8B are diagrams showing another conventional composite roll made of cemented carbide, in which FIG. 8A is a schematic sectional view in the direction of the rotation axis, and FIG. 8B is a schematic sectional view in the direction perpendicular to the rotation axis.

[Explanation of symbols]

 1, 11 outer layer 2 inner layer 3 shaft core 4 side end ring 1A, 21A joint 5 molded member 21, 22 cemented carbide sleeve

Continued on the front page (72) Inventor Toshiki Hiruta 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Pref. Kawasaki Steel Research Institute Co., Ltd. (72) Inventor Toshiyuki Hattori 1-9-1 Kitahama, Wakamatsu-ku, Kitakyushu-shi, Fukuoka Metal Corporation Wakamatsu Factory (72) Inventor Maki Horiuchi 1-9-1 Kitahama-ku, Wakamatsu-ku, Kitakyushu-shi, Fukuoka F-term in Wakamatsu Factory (Reference) 4E016 AA02 AA06 CA04 CA08 CA09 DA04 EA06 EA12 EA22 FA04 FA07 4K018 HA03 KA17

Claims (7)

[Claims] 1. An outer layer made of a cemented carbide formed by integrating a plurality of pre-sintered cylindrical molded members, and an inner layer made of a steel-based material formed on the inner surface of the outer layer. A cemented carbide composite roll formed by fitting the fixed sleeve to a steel shaft core and fixing the same, wherein the sleeve has a length of 520 mm or more and 6000 mm or less. Composite roll made of hard alloy. 2. The cemented carbide composite roll according to claim 1, wherein the number of said molded body members is 5 or more and 30 or less. 3. The cemented carbide alloy roll according to claim 1, wherein the composite roll has an outer diameter of 150 mm or more and 800 mm or less and is used as a work roll for a cold tandem rolling mill. 4. The cemented carbide alloy roll according to claim 1, wherein the outer roll has an outer diameter of 500 mm or more and 1500 mm or less and is used as a work roll for a hot rough rolling mill. 5. The cemented carbide alloy roll according to claim 1, wherein the outer diameter is 400 mm or more and 1400 mm or less and used as a work roll for a hot finishing mill. 6. The cemented carbide composite roll according to claim 1, wherein the composite roll has an outer diameter of 500 mm or more and 1500 mm or less and is used as a work roll for a plate rolling mill. 7. The cemented carbide composite roll according to claim 1, wherein the composite roll has an outer diameter of not less than 600 mm and not more than 2000 mm and is used as a work roll for a section steel mill.