JP2011206819A - Rolling roll and method for reutilizing rolling roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling roll which, even when cracking has occurred in an outer layer, can prevent crack damage of the whole roll, does not cause cracking in the outer layer by tensile stress due to a difference in coefficient of thermal expansion in hot rolling, and can satisfactorily effectively utilize a material for rolling roll formation, and to provide a method for effectively reutilizing the rolling roll.SOLUTION: A rolling roll 1 comprises an inner layer part 4 fitted in an inner periphery of an outer layer part 3 having a rolling part 2 on an outer periphery thereof to render the outer layer part 3 and the inner layer part 4 integrally rotatable, the both the outer layer part 3 and the inner layer part 4 being formed of a cemented carbide. The outer periphery part of the rolling roll which has been integrally formed with the cemented carbide is removed to reduce the outer diameter, and the rolling roll is reutilized as the inner layer part 4 in the rolling roll 1. Alternatively, the inner layer part 4 is removed from the outer layer part 3 in the rolling roll 1 and is then fitted in an inner periphery of other outer layer part.

Description

  The present invention relates to a rolling roll having a rolling part formed on the outer periphery, and a method for reusing such a rolling roll.

  As a rolling roll that is rolled on a shaft of a rolling mill and rolled into a deformed steel bar such as a reinforcing bar by a rolling part (caliber) formed on the outer periphery thereof, a cemented carbide with high hardness is used. Conventionally, a solid carbide roll which is integrally formed by the above-described method and is press-fitted into the shaft via a taper sleeve is known.

  However, such a solid carbide roll has high hardness, but has low toughness, and once cracks occur in the outer peripheral part to be rolled, there is a problem that it progresses to the inner peripheral part and leads to breakage. Also, only the outer peripheral rolling part is used for rolling, and there is a limit to what can be reused by polishing when the rolling part is worn. When the rolling part reaches the scrap diameter, it is expensive cemented carbide There is also a problem that it must be disposed of with most of it remaining.

  Therefore, for example, in Patent Documents 1 to 3, an outer layer material made of cemented carbide is applied to the outer periphery of the inner layer material made of steel material having excellent toughness, a circumferential compressive residual stress is applied to the outer layer surface, or a metal layer is applied. For example, an intermediate layer is provided on the inner side of the outer layer material, and diffusion bonding is performed simultaneously with sintering.

JP-A-10-005823 JP 2001-047110 A JP 2001-047111 A

  However, in the rolling roll in which the inner layer material is made of steel and the outer layer material is made of cemented carbide in this way, the tensile stress is applied to the outer layer material in the case of hot rolling due to the difference in thermal expansion coefficient between these steel materials and cemented carbide. Even if compressive residual stress is applied to the outer layer surface or a metal layer or intermediate layer is provided between the inner and outer layer materials, cracks may occur in the outer layer material made of cemented carbide with poor toughness. There is no way to eliminate the risk of occurrence.

  In addition, as described in these Patent Documents 1 to 3, when the cemented carbide that is the outer layer material is diffusion-bonded to the outer periphery of the inner layer material simultaneously with the sintering, the inner layer material is removed from the outer layer material. If the inner layer material, which is difficult and has a low hardness, is worn out, it must be discarded even if the rolled portion of the outer layer material is usable. Furthermore, when the rolling part reaches the scrap diameter, the entire inner layer material must be discarded, and it is difficult to say that the inner layer material is cheaper than the outer layer material, but is sufficiently utilized effectively.

  The present invention has been made under such a background, and it is possible to prevent the entire roll from being damaged even if cracks occur in the outer layer, and of course, due to the difference in thermal expansion coefficient during hot rolling. The present invention provides a rolling roll that does not cause cracks in the outer layer due to tensile stress, and that can sufficiently utilize the material forming the rolling roll, and an effective reuse method for such a rolling roll. The purpose is to provide.

  In order to solve the above-described problems and achieve such an object, the rolling roll of the present invention is configured such that the inner layer portion is fitted to the inner periphery of the outer layer portion having the rolled portion on the outer periphery and is integrally rotatable. The outer layer portion and the inner layer portion are both formed of cemented carbide.

  In the rolling roll configured as described above, the inner layer portion is fitted to the inner periphery of the outer layer portion, and even if a crack occurs in the outer layer portion made of a cemented carbide having low toughness, the inner layer portion stops at the fitting surface. It does not progress, and the rolling roll can be restored by exchanging the outer layer part. This is the same even when wear occurs in the inner layer part. Since the inner and outer layer parts are fitted and integrated, the inner layer part is removed from the inner periphery of the outer layer part and replaced, so that It can be restored.

  And since this inner layer part is also formed of the same cemented carbide as the outer layer part, there is no difference in the thermal expansion coefficient between the inner and outer layer parts, even if there is a difference due to the difference in the type of cemented carbide. It is. Therefore, it is possible to prevent the tensile stress from acting on the outer layer portion even in hot rolling, thereby reliably preventing the occurrence of cracks in the outer layer portion.

  Here, when the outer layer portion and the inner layer portion are fitted by an interference fit, the interference of the interference fit is in a range of 0.01% to 0.03% with respect to the fitting diameter. Is desirable. If the ratio of the tightening allowance to the fitting diameter is smaller than this range, slip may occur between the inner and outer layer portions during rolling, whereas if larger than this range, the tensile stress is applied to the outer layer portion due to the interference fit. There exists a possibility that it will become impossible to prevent generation | occurrence | production of a crack reliably. However, when it is attached to the shaft of a rolling mill via a taper sleeve like the above-mentioned solid carbide roll, an internal pressure acts from the inner layer part to the outer layer part by this taper sleeve. Good.

  On the other hand, the inner layer portion of such a roll may of course be formed from a cemented carbide with a predetermined outer diameter as the inner layer portion from the beginning. In the method, first, the outer diameter of the rolling roll formed integrally with the cemented carbide alloy, such as the cemented carbide solid roll that has reached the scrap diameter, is removed to reduce the outer diameter, and the rolling according to the present invention is performed. By reusing as the inner layer part of the roll, the cemented carbide material can be effectively used, which is efficient and economical. Moreover, in the recycling method of the rolling roll of the present invention, secondly, the inner layer portion is removed from the outer layer portion of the rolling roll of the present invention and fitted to the inner periphery of the other outer layer portion. It is possible to effectively use the hard alloy material, which is also efficient and economical.

  As described above, according to the rolling roll of the present invention, it is possible to prevent the outer layer portion having low toughness from being cracked, and even if the outer layer portion is cracked or the inner layer portion is worn. However, it is possible to avoid having to discard the entire roll, and the cemented carbide material can be effectively used. Moreover, according to the recycling method of the rolling roll of this invention, such a rolling roll can be obtained efficiently and economically using a cemented carbide material effectively.

It is sectional drawing which shows one Embodiment of the rolling roll of this invention. It is a figure explaining one Embodiment of the reuse method of the rolling roll of this invention in the case of manufacturing the embodiment shown in FIG. 1 by reusing a solid carbide roll. It is sectional drawing for demonstrating the Example of this invention. It is an expanded sectional view of the outer layer part in FIG.

  FIG. 1 shows an embodiment of a rolling roll according to the present invention. The rolling roll 1 of the present embodiment has a substantially cylindrical shape or an annular shape centered on the axis O, and a groove-shaped rolling portion 2 is formed on the outer periphery of the rolling roll 1 around the axis O. It is formed so as to go around. In such a rolling roll 1, the pair of rolling rolls 1 have the axes O parallel to each other, and the inner peripheral portions of the rolling rolls 1 face each other in the cross section along these axes O. It is attached to the shaft of a rolling mill and rolled by passing the workpiece between the opposing rolling sections 2 while being rotated in the opposite direction around the axis O.

  And this rolling roll 1 is fitted to the inner periphery of this outer layer part 3 with the outer layer part 3 in which the said rolling part 2 was formed in the outer periphery, and the outer peripheral part is attached to the said shaft by the inner peripheral part being attached to the said shaft. 3 and an inner layer portion 4 that are rotated together with the outer layer portion 3. The outer layer portion 3 and the inner layer portion 4 are both formed of a cemented carbide containing WC as a main component and a binder such as Co. Here, the cemented carbide forming the outer layer portion 3 and the inner layer portion 4 may be the same or different in the binder component, the WC particle size, and the like.

  In addition, the inner peripheral surface of the outer layer portion 3 and the outer peripheral surface of the inner layer portion 4 which are fitting surfaces that are in close contact with each other are cylindrical surfaces centered on the axis O, and in the present embodiment, these inner and outer layer portions 3, 4 is fitted by an interference fit. Specifically, the outer layer portion 3 is heated and thermally expanded, or the inner layer portion 4 is cooled and contracted, or both of them are performed simultaneously, and the inner and outer layer portions 3 and 4 are fitted and left at room temperature. The fitting surface is brought into close contact.

  In the present embodiment, the tightening allowance at the time of the interference fitting is in the range of 0.01% to 0.03% with respect to the fitting diameter. That is, when the outer diameter of the inner layer portion 4 at normal temperature is D, and the diameter (fitting diameter) of the fitting surface in a state of being fitted with an interference fit is d, (D−d) / d is 0. The range is 01 to 0.03. However, when the rolling roll 1 is attached to the shaft via a taper sleeve, the inner layer portion 4 is given an internal pressure by the taper sleeve and expands to be brought into close contact with the inner peripheral surface of the outer layer portion 3. Therefore, the ratio of the fastening allowance to the fitting diameter may be less than 0.01%, for example, the fastening allowance may be zero.

  Therefore, in the rolling roll 1 configured in this way, even if a crack occurs from the rolled portion 2 or the like during rolling in the outer layer portion 3 where the rolled portion 2 is formed, the rolling roll 1 stops at the mating surface of each other. It does not progress to the inner layer part 4. For this reason, the rolling roll 1 can be restored by exchanging the outer layer part 3, and the inner layer part 4 made of cemented carbide can be used effectively, which is efficient and economical. On the other hand, even when the inner layer portion 4 is worn away and cannot be used, only the inner layer portion 4 needs to be replaced.

  Further, in the rolling roll 1 having the above-described configuration, since the inner and outer layer portions 3 and 4 are both formed of cemented carbide, thermal expansion is achieved if the cemented carbide forming the inner and outer layer portions 3 and 4 is of the same type. There is no difference in the coefficients, and the difference is very small even with different grades. For this reason, even when the work piece is rolled in hot rolling, it is possible to prevent the tensile stress due to the thermal expansion of the inner layer portion 4 from acting on the outer layer portion 3, and the outer layer portion 3 is cracked by such tensile stress. Can be prevented. Moreover, since the whole rolling roll 1 will be formed with a cemented carbide, roll rigidity is high like a cemented carbide solid roll, and it can raise rolling torque compared with the thing of patent documents 1-3. The advantage is also obtained.

  Furthermore, in this embodiment, these inner and outer layer portions 3 and 4 are fitted by interference fitting, and the ratio of the interference to the fitting diameter is in the range of 0.01% to 0.03%. . However, if this ratio is too small, the outer layer 3 may slip with respect to the inner layer 4 during rolling. Conversely, if this ratio is too large, a tensile stress acts on the outer layer 3 due to this interference fit. However, according to this embodiment, by setting the tightening margin within the above range, it is possible to prevent the occurrence of these slips and cracks as demonstrated in the examples described later. As described above, even when one of the inner and outer layer portions 3 and 4 is replaced, it can be easily attached and detached.

  By the way, the rolling roll 1 having such a configuration is such that the inner and outer layer parts 3 and 4 are sintered in advance by forming a green compact from powdered cemented carbide raw material so as to have a predetermined size and shape. Of course, the obtained sintered body may be manufactured by fitting as described above after finishing, but for the inner layer portion 4, the first implementation of the method for reusing a rolling roll of the present invention is included. As shown in FIG. 2, for example, a cemented carbide solid roll 11 having a cemented carbide alloy as shown in FIG. 2 (a) is used for rolling. As shown in FIG. 2 (b), the waste diameter is removed and the outer periphery is polished and removed as shown in FIG. 2 (c) so that it can be reused as the inner layer portion 4 having a predetermined outer diameter. It may be.

  In addition, as a second embodiment of the method for reusing a rolling roll of the present invention, the rolling diameter of the rolling roll 1 of the above embodiment is used for rolling, and the scrap diameter is repeated while polishing is repeated every time the rolled portion 2 wears. When the inner layer portion 4 is removed from the outer layer portion 3 whose outer diameter has reached the scrap diameter, and fitted to the inner periphery of another newly produced outer layer portion 3, The unit 4 may be reused.

  According to the method for reusing the rolling rolls of the first and second embodiments, the inner peripheral portion of the solid carbide roll 11 having a discarded diameter, which has been conventionally discarded as a whole in the first embodiment, is implemented as described above. Can be reused as the inner layer part 4 in the rolling roll 1 of the embodiment, and in the second embodiment, the inner layer part 4 in the rolling roll 1 of the above embodiment is repeated and reused as the inner layer part 4 of the new rolling roll 1. In any case, the cemented carbide material can be effectively used, which is efficient and economical.

  And if especially the ratio of the interference with respect to a fitting diameter is made into the said range like the rolling roll 1 of the said embodiment, the inner-layer part 4 of the new rolling roll 1 is used like the reuse method of 2nd Embodiment. When reused as the inner layer part 4, while preventing the occurrence of slips and cracks during rolling, it becomes easy to attach and detach with the old and new outer layer part 3 and promote more efficient reuse of the rolling roll. It becomes possible.

  Hereinafter, an example is given and the change of the characteristic when the ratio of the interference with respect to a fitting diameter is changed in the rolling roll of the said embodiment is demonstrated. In this example, in the rolling roll of the above-described embodiment, the depth (caliber depth) of the recessed groove-shaped rolling part is 8 types in total, each having 4 types of outer diameters of the outer layer portion. For the rolling roll, the work piece was rolled at a predetermined range of rolling torque while changing the ratio of the tightening allowance with respect to the fitting diameter, and after rolling, the presence of slip, breakage, and detachability of the inner and outer layer portions were examined. . The results are shown in the table together with the allowance for each example.

  The rolling rolls used in the examples are formed of cemented carbide made of GA5315 manufactured by Mitsubishi Materials Corporation (name changed to GX315 from April 2010) in both the inner and outer layers. Rolling with a steel bar of grade S45C was performed until the reduction rate was 20% by hot rolling at 800 to 1100 ° C.

  Also, for the presence or absence of slip, check whether the outer layer portion is displaced in the circumferential direction after rolling, and for the presence or absence of cracks, check the presence or absence of cracks, cracks and cracks in the inner and outer layer portions after rolling. As a result of confirmation, when these occurred, those with a length of 10 mm or less were indicated by triangular marks in the table (in the present example, there was no larger one). Further, regarding the detachability, those in which the inner layer portion could be removed from the outer layer portion by heating the outer layer portion after rolling were indicated by circles, and those that were not indicated by x marks in the table.

  In the rolling roll 1 schematically shown in FIG. 3, the outer diameter (a dimension in FIG. 3) of the outer layer part 3 is 150 mm, and the fitting length (b dimension in FIG. 3) of the inner and outer layer parts 3 and 4 in the axis O direction. 75 mm, the inner layer part 4 has an inner diameter of 90 mm, which is 60% of the outer diameter of the outer layer part 3, and the outer groove part 3 has a semicircular groove-shaped rolling part 2 having a semi-elliptical section as shown in FIG. The caliber depth (c dimension in FIG. 4) was 2 mm, and the width in the direction of the axis O (h dimension in FIG. 4) was 4 mm. At this time, the fitting diameter (e dimension in FIG. 3) of the inner and outer layer parts 3 and 4 is 111 mm, the radial thickness of the outer layer part 3 (f dimension in FIG. 3) is 19.5 mm, and the radial direction of the inner layer part 4 The thickness (g dimension in FIG. 3) was 10.5 mm.

  And in such a rolling roll, as shown in the following table 1, the above conditions were obtained with rolling torques of 490 to 980 N · m, respectively, by adjusting the tightening margin and changing the ratio of the tightening margin to the fitting diameter. After the rolling process, the slip, the presence or absence of breakage, and the detachability were examined as described above. The results are also shown in Table 1.

  In the rolling roll 1 schematically shown in FIG. 3, the outer diameter of the outer layer portion 3 (a dimension in FIG. 3) is 150 mm as in Example 1, and the fitting length of the inner and outer layer portions 3 and 4 in the direction of the axis O (FIG. 3). B dimension) is 75 mm, the inner layer portion 4 has an inner diameter of 90 mm which is 60% of the outer diameter of the outer layer portion 3, and the outer layer portion 3 has a semi-elliptical concave groove-shaped rolled portion 2 as shown in FIG. In Example 2, only one line was formed with a depth (caliber depth; c dimension in FIG. 4) of 5 mm and a width in the axis O direction (h dimension in FIG. 4) of 10 mm. In Example 2, the fitting diameter (e dimension in FIG. 3) of the inner and outer layer portions 3 and 4 is 99 mm, and the radial thickness (f dimension in FIG. 3) of the outer layer portion 3 is 25.5 mm. The thickness (g dimension in FIG. 3) of the radial direction of the part 4 was 4.5 mm.

  And in such a rolling roll, as shown in the following table 2, by adjusting the tightening margin and changing the ratio of the tightening margin to the fitting diameter, each of 490 to 980 N · m as in Example 1 After rolling with the rolling torque under the above conditions, the slip, the presence or absence of breakage, and the detachability were examined as described above. The results are also shown in Table 2.

  In the rolling roll 1 schematically shown in FIG. 3, the outer diameter of the outer layer part 3 (a dimension in FIG. 3) is 200 mm, and the fitting length (b dimension in FIG. 3) of the inner and outer layer parts 3 and 4 in the axis O direction. 100 mm, the inner layer part 4 has an inner diameter of 120 mm, which is 60% of the outer diameter of the outer layer part 3, and the outer groove part 3 has a semicircular groove-shaped rolling part 2 having a semi-elliptical section as shown in FIG. The caliber depth (c dimension in FIG. 4) was 5 mm, and the width in the direction of the axis O (h dimension in FIG. 4) was 10 mm. At this time, the fitting diameter (e dimension in FIG. 3) of the inner and outer layer parts 3 and 4 is 144 mm, the radial thickness of the outer layer part 3 (f dimension in FIG. 3) is 28.0 mm, and the radial direction of the inner layer part 4 The thickness (g dimension in FIG. 3) was 12.0 mm.

  And in such a rolling roll, as shown in the following table 3, with the rolling torque of 490 to 1960 N · m, the above conditions were adjusted with the rolling rolls having the tightening margin adjusted and changing the ratio of the tightening margin to the fitting diameter, respectively. After the rolling process, the slip, the presence or absence of breakage, and the detachability were examined as described above. The results are also shown in Table 3.

  In the rolling roll 1 schematically shown in FIG. 3, the outer diameter of the outer layer portion 3 (a dimension in FIG. 3) is 200 mm as in Example 3, and the fitting length in the direction of the axis O of the inner and outer layer portions 3 and 4 (FIG. 3). B dimension) is 100 mm, the inner layer part 4 has an inner diameter of 120 mm, which is 60% of the outer diameter of the outer layer part 3, and the outer layer part 3 has a semi-elliptical concave groove-shaped rolled part 2 as shown in FIG. In Example 4, the depth (caliber depth; c dimension in FIG. 4) was 10 mm, and the width in the axis O direction (h dimension in FIG. 4) was 20 mm, and only one line was formed. In Example 4, the inner and outer layer portions 3, 4 have a fitting diameter (e dimension in FIG. 3) of 130 mm, and the outer layer portion 3 has a radial thickness (f dimension in FIG. 3) of 35.0 mm. The thickness (g dimension in FIG. 3) of the radial direction of the part 4 was 5.0 mm.

  And in such a rolling roll, as shown in the following table 4, by adjusting the tightening allowance and changing the ratio of the tightening allowance to the fitting diameter, each of 490 to 1960 N · m as in Example 3 After rolling with the rolling torque under the above conditions, the slip, the presence or absence of breakage, and the detachability were examined as described above. The results are also shown in Table 4.

  In the rolling roll 1 schematically shown in FIG. 3, the outer diameter (a dimension in FIG. 3) of the outer layer part 3 is 250 mm, and the fitting length (b dimension in FIG. 3) of the inner and outer layer parts 3 and 4 in the axis O direction. The inner layer part 4 has an inner diameter of 150 mm, which is 60% of the outer diameter of the outer layer part 3, and the outer groove part 3 has a semicircular groove-shaped rolling part 2 having a semi-elliptical section as shown in FIG. The caliber depth (c dimension in FIG. 4) was 5 mm, and the width in the direction of the axis O (h dimension in FIG. 4) was 10 mm. At this time, the fitting diameter (e dimension in FIG. 3) of the inner and outer layer parts 3 and 4 is 189 mm, the radial thickness of the outer layer part 3 (f dimension in FIG. 3) is 30.5 mm, and the radial direction of the inner layer part 4 The thickness (g dimension in FIG. 3) was 19.5 mm.

  And in such a rolling roll, as shown in the following table 5, with the rolling roll which adjusted the interference allowance and changed the ratio of the interference allowance with respect to the fitting diameter, each of the above conditions with a rolling torque of 1960-3920 N · m After the rolling process, the slip, the presence or absence of breakage, and the detachability were examined as described above. The results are also shown in Table 5.

  In the rolling roll 1 schematically shown in FIG. 3, the outer diameter of the outer layer portion 3 (dimension a in FIG. 3) is 250 mm as in Example 5, and the fitting length of the inner and outer layer portions 3 and 4 in the direction of the axis O (FIG. 3). B)) is 150 mm, the inner diameter of the inner layer portion 4 is 150 mm which is 60% of the outer diameter of the outer layer portion 3, and the outer groove portion 3 has a semi-elliptical concave groove-shaped rolled portion 2 as shown in FIG. In Example 6, only one strip was formed with a depth (caliber depth; c dimension in FIG. 4) of 10 mm and a width in the axis O direction (h dimension in FIG. 4) of 20 mm. In Example 6, the fitting diameter (e dimension in FIG. 3) of the inner and outer layer parts 3 and 4 is 175 mm, and the radial thickness (f dimension in FIG. 3) of the outer layer part 3 is 37.5 mm. The thickness (g dimension in FIG. 3) of the radial direction of the part 4 was 12.5 mm.

  And in such a rolling roll, as shown in the following table 6, by adjusting the tightening allowance and changing the ratio of the tightening allowance with respect to the fitting diameter, each of 1960-3920 N · m as in Example 5 After rolling with the rolling torque under the above conditions, the slip, the presence or absence of breakage, and the detachability were examined as described above. The results are also shown in Table 6.

  In the rolling roll 1 schematically shown in FIG. 3, the outer diameter (a dimension in FIG. 3) of the outer layer part 3 is 300 mm, and the fitting length (b dimension in FIG. 3) of the inner and outer layer parts 3 and 4 in the axis O direction. The inner layer portion 4 has an inner diameter of 180 mm, which is 60% of the outer diameter of the outer layer portion 3, and the outer groove portion 3 has a semi-elliptical groove-shaped rolling portion 2 having a semi-elliptical section as shown in FIG. The caliber depth (c dimension in FIG. 4) was 10 mm, and the width in the axis O direction (h dimension in FIG. 4) was 20 mm. At this time, the fitting diameter (e dimension in FIG. 3) of the inner and outer layer parts 3 and 4 is 220 mm, the radial thickness of the outer layer part 3 (f dimension in FIG. 3) is 40.0 mm, and the radial direction of the inner layer part 4 The thickness (g dimension in FIG. 3) was 20.0 mm.

  And in such a rolling roll, as shown in following Table 7, with the rolling roll which adjusted the interference allowance and changed the ratio of the interference allowance with respect to a fitting diameter, the said conditions by the rolling torque of 3920-5880 N * m, respectively. After the rolling process, the slip, the presence or absence of breakage, and the detachability were examined as described above. The results are also shown in Table 7.

  In the rolling roll 1 schematically shown in FIG. 3, the outer diameter of the outer layer portion 3 (a dimension in FIG. 3) is 300 mm, and the fitting length of the inner and outer layer portions 3 and 4 in the direction of the axis O (FIG. 3). B dimension) is 150 mm, the inner layer portion 4 has an inner diameter of 180 mm, which is 60% of the outer diameter of the outer layer portion 3, and the outer layer portion 3 has a semi-elliptical groove-shaped rolled portion 2 as shown in FIG. In Example 8, only one line was formed with a depth (caliber depth; c dimension in FIG. 4) of 20 mm and a width in the axis O direction (h dimension in FIG. 4) of 40 mm. In Example 8, the fitting diameter (e dimension in FIG. 3) of the inner and outer layer portions 3 and 4 is 190 mm, and the radial thickness (f dimension in FIG. 3) of the outer layer portion 3 is 55.0 mm. The thickness (g dimension in FIG. 3) of the radial direction of the part 4 was 5.0 mm.

  And in such a rolling roll, as shown in the following table 8, by adjusting the tightening margin and changing the ratio of the tightening margin to the fitting diameter, each of 3920-5880 N · m as in Example 7 After rolling with the rolling torque under the above conditions, the slip, the presence or absence of breakage, and the detachability were examined as described above. The results are also shown in Table 8.

  From the results of Tables 1 to 8, in any of Examples 1 to 8, breakage is recognized when the tightening margin is small and the ratio to the fitting diameter is 0.005% which is less than 0.01%. In addition, it was confirmed that the outer layer portion 3 slipped with respect to the inner layer portion 4 during rolling, although the detachability was good. On the other hand, in the case where the tightening allowance was large and the ratio to the fitting diameter was 0.04% exceeding 0.03%, no slip was observed, but the above small cracks (cracks and Cracks were observed, and the inner and outer layer portions 3 and 4 were not easily attached and detached. However, it does not reach a breakage in which the outer layer portion 3 is largely missing.

  On the other hand, when the ratio of the tightening margin to the fitting diameter is in the range of 0.01% to 0.03%, no slip or breakage is observed after rolling, and smooth and stable rolling is performed. I was able to. Also, the inner and outer layer portions 3 and 4 were easily attached and detached.

DESCRIPTION OF SYMBOLS 1 Roll roll 2 Roll part 3 Outer layer part 4 Inner layer part O The axis of the roll 1

Claims (4)

  The inner layer portion is fitted to the inner periphery of the outer layer portion having a rolled portion on the outer periphery and is integrally rotatable, and both the outer layer portion and the inner layer portion are formed of cemented carbide. Rolling roll.   The outer layer portion and the inner layer portion are fitted by an interference fit, and a tightening margin of the interference fit is in a range of 0.01% to 0.03%. Rolling rolls.   The rolling characterized by removing the outer peripheral part of the rolling roll integrally formed with the cemented carbide and reducing the outer diameter, and reusing it as the inner layer part of the rolling roll according to claim 1 or 2. How to reuse roles.   A method for reusing a rolling roll, comprising: removing the inner layer portion from the outer layer portion of the rolling roll according to claim 1 or 2 and fitting the inner layer portion into an inner periphery of another outer layer portion.

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