KR930002864B1 - Multiple roll mill under high load with a work roll for controlling radius - Google Patents

Abstract

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Description

Heavy duty large rolling mill with variable diameter working roller

1 is a schematic of a roll arrangement of a high load 12 stage rolling mill of varying diameters of work rolls according to the present invention.

2 is a longitudinal sectional view of the rolling mill.

3 is a graph showing the range of the roller diameter ratio.

4 is a chart showing roll life.

The present invention relates to a multi-stage rolling mill for high loads, in which the roll diameter of the working roller can be varied. In a 12-stage rolling mill where the upper and lower working rollers for rolling the material to be rolled are supported by three backup rollers through two intermediate rollers, respectively, the load is biased when the diameter of the backup roller is the same to shorten the bearing life. There was a problem.

In order to solve the problem described above, an apparatus is proposed which makes the durability of the bearing for a backup roller uniform by varying the roll diameter of the backup roller according to the assigned rolling load (see Japanese Patent Laid-Open No. 57-206507). .

The conventional publication discloses a multi-stage rolling mill using a work roller having a single diameter, wherein the roll diameter ratio between the central backup roller and the opposite ends backup roller is 0.2 to 0.7, preferably 0.4 to 0.6. Is set. In other words, the diameter of the roll between the central backup roller and the two-sided backup roller is changed in various ways to secure the life of the roller bearing, and when the life of the central backup roller is approximately the same as that of the both backup roller, the ratio of the diameter to the ratio of the roller diameter Obtained as There is also a multi-stage rolling mill in which the roll diameter of the working roll can be changed to at least two types. In such multistage rolling mills where the diameter of the working roller can be changed, the above-described prior art can only be applied to change in order to determine an appropriate ratio with respect to the diameter of the backup roller so that the life of the backup roller is approximately the same. That is, the roll diameter ratio of the backup roller in the prior art is determined for a work roller having a single diameter. However, if the roll diameter of the working roller changes, the load placed on each backup roller also changes, so the appropriate ratio of the roll diameter also changes. The purpose of changing the diameter of the work roll is to improve productivity and shape with one unit of the rolling mill.

That is, when a large diameter working roller is used, high speed rolling is possible, a better shape is obtained, and stable rolling is possible. This is because the large diameter working roller has a large heat capacity, so that the rise of the roll temperature due to heat generated by friction, etc. is reduced, and the influence of heat generated in the material to be rolled to a predetermined shape is reduced. Moreover, when a small diameter working roller is used, a high rate of pressure drop can be obtained, and the number of passes can be reduced to improve productivity. This is due to the fact that the amount of pressure drop per pass can be increased since the required rolling force applied to the material to be rolled can be reduced relatively. Thus, for example, when a large rolling mill with a variable diameter of the working roller is used as the reverse rolling mill and the finished product is rolled in six passes, the small diameter working roller may be used to roll the first to fourth parts so as to roll the finished product with a high ratio of pressure drop. The large diameter working roller is used in the pass and is used in the final fifth to sixth passes to get a better shape. That is, in a multi-stage rolling machine in which the work roller diameter can be changed, not only the roll diameter of the work roller is different, but also the use frequency of the large diameter work roller is different from the use frequency of the small diameter work roller. Therefore, in the case of obtaining the roll diameter ratio of the backup roller, it is not a proper method to simply use the middle roller between the large diameter work roller and the small diameter work roller to determine the roll diameter ratio of the backup roller. Therefore, it is an object of the present invention to provide a high load multi-stage rolling mill whose work roller diameter can be changed, in view of the fact that the radius of the work roller is changed and the frequency of use of different types of work rollers is different. The service life of the bearing is nearly uniform, extending the life of the entire backup roller.

In order to achieve the above object, the present invention adopts the following means.

According to one aspect of a high load 12-stage rolling mill having a variable working diameter of the roller according to the invention, each working roller 2 of the upper and lower working rollers for rolling the material 1 to be rolled has a middle roll having the same diameter. It is supported by three backup rolls (5, 6 and 7) through (3 and 4), and in the high load 12-stage rolling mill where the roll diameter of the upper and lower working rollers (2) can be changed to at least two types. In this case, the roller diameter of the working roller 2 having the largest diameter among the roller diameters of the working roller 2 is substantially the same as that of the intermediate rollers 3 and 4, and the working diameter of the working roller 2 having the minimum diameter. Double-sided backup rolls with a roll diameter, the roll diameter of the central backup roll 5 for supporting two middle rolls 3 and 4 simultaneously, and the same diameter for supporting one middle roll 3 and 4 The ratio of the roll diameter between the roll diameters of (6 and 7) is (1: 4: 5.2), ( A 12-roller for high load is provided, which is in the range of 1: 4.5: 5.2), (1: 4.5: 5.75), (1: 4.22: 6) and (1: 4: 6).

The rolling mill of the present invention is used in a reverse type. For example, when a finished product is obtained in 6 passes, a small diameter working roller is used for the first 1 to 4 passes, and rolling is performed using a large diameter working roller for the last 5 to 6 passes. The purpose of using a small diameter working roller is to obtain a high ratio of pressure drop, and the purpose of using a large diameter working roller is to obtain a better shape and to perform high speed rolling. In order to roll ductile materials such as copper alloys such as pure copper, brass, and 42-nickel alloys, the use of large diameter working rolls is relatively high. According to the statistics of the survey conducted according to the frequency of use of the large diameter work roller and the small diameter work roller, the use frequency of the large diameter roll was 20 to 30% and the use frequency of the small diameter roll was 80 to 70%. Therefore, the roll diameter ratio in the present invention is set based on the frequency of use.

In the present invention, the roll diameter of the large diameter working roller is manufactured to be approximately equal to the roll diameter of the middle roller for the following reason. That is, the larger the diameter is, the better, to perform high-speed rolling, which is the purpose of using a large diameter working roller, and to obtain a better shape. However, if the diameter of the large diameter working roller is made larger than the diameter of the middle roll, the installation stability of the roll is impaired, so that the diameter which is approximately equal to the middle roll is the limit. The roller diameter of the small diameter working roller is not particularly limited. However, if the angle formed between the axes of both the backup roller, the central roller and the small diameter roller is not less than 180 °, the intermediate roller is released, and therefore the ratio with the other roller diameter is automatically determined in consideration of the arrangement of the rollers. This ratio is a well-known value and is not specifically limited.

In the present invention, the large diameter roll is set to be about twice the size of the small diameter roll (1.8 to 2.0). In determining the diameter ratio of the backup roll, the diameter of the small diameter working roller is used as a reference for the following reasons. That is, since the diameter of the backup roller cannot be properly selected and the roll arrangement of the whole rolling mill cannot be specified only by the ratio of the diameter of the backup roller at both ends and the center part, the working roller is used as a reference value in determining the ratio of the backup roller diameter. Used. Moreover, small diameter working rolls are usually used for working rolls as reference values. Large diameter rolls can also be used as reference values. The ratio of the diameters between the central backup roller and the double-sided backup roller is determined by the balance of the bearing life of both backup rollers using the small and large diameter rollers as a whole. A ratio closer to the ratio of 1: 4: 6 is advantageous when the ratio of use of the small diameter roll is high, whereas a ratio closer to the ratio of 1: 4.5: 5.2 is advantageous when the ratio of the use of the large diameter roll is high. Do. That is, if the diameter ratio between the both end backup roller and the central backup roller is 0.67 (1: 4: 6) or less, as is apparent from the description of FIG. 4 to be described later, the life of the central backup roller is shorter than that of the both backup rollers. As a result, the life of the backup roller as a whole is shortened. If the diameter ratio between both backup and central backup rollers is greater than 0.87 (1: 4.5: 5.2), the lifetime of both backup rollers will be shorter than that of central backup rollers, and the life of backup rollers will be shortened overall. The ratio of the diameter of both back-up rollers to the diameter of the working rollers is determined from the stability of the roll arrangement, such as the deviation of the rolls, in view of the limitation of the diameter of the middle roller. This reason is that if the ratio of the diameter of the working roller to the diameter of the central backup roller is smaller than (1: 4), the diameter of the backup roller becomes so small that rolling with high loads cannot be achieved, whereas (1 Greater than 4.5), the stability of the roll array is degraded. If the ratio of the diameter of the roll exceeds (1: 4.5: 5.75) and (1: 4.22: 22: 6), both backup and central backup rollers are interfering with each other and the rollers are not arranged. Therefore, the above range is excluded.

Embodiments of the present invention will now be described with reference to the drawings. 1 is a layout view of the roll of a high load 12-stage rolling mill in which the diameter of the working roller can be changed. In FIG. 1, the use state of the upper side of the material to be rolled is different from its lower side. In other words, the upper side shows the roll arrangement when the working diameter of the minimum diameter is used as the work roller, and the lower side shows the roll arrangement when the working diameter of the maximum diameter is used as the work roller. Naturally, the diameters of the upper and lower working rollers in the actual state of use are the same except for certain cases.

이다. 제 3 도에 도시된 바와같이, 작업로울(2)의 최소로울직경, 중앙백업로울(5)의 로울직경 및 양단백업로울(6과 7)의 로울직경사이의 비는 (1 : 4 : 5.2), (1 : 4.5 : 5.2), (1 : 4.5 : 5.75), (1 : 4.22 : 6) 및 (1 : 4 : 6 :)의 범위내에서 설정된다. 제 4 도는 상기 로울직경의 비를 얻기 위한 백업로울의 수명에 관한 다이아그램을 표시한다. 백업로울의 로울수명(L_h)은 다음식과 표1 및 2에 주어진 조건에 의해 얻었다.The above-mentioned rolling mill is equipped with upper and lower working rolls 2 for rolling the material 1 to be rolled. Each working roll 2 is supported by upper and lower middle rolls 3 and 4. The diameters of these two middle rolls 3 and 4 are the same. Each intermediate roll 3, 4 is supported by three upper and lower backup rolls 5, 6, 7. Of the three backup rollers (5, 6, 7), the central backup roller (5) simultaneously supports the two intermediate rollers (3, 4). Two backup rolls 6 and 7 at both ends support one middle roll 3 or 4. The roller diameter D ₂ of both the backup rollers 6 and 7 is the same. The roll diameter D ₁ of the central backup roll 5 is different from the diameter D ₂ of both backup rollers. As shown in the longitudinal cross-sectional view of the rolling mill of FIG. Supported. The working roll 2 is replaceable regardless of the stage from the minimum diameter to the maximum diameter. The maximum diameter of the work roll 2 is approximately equal to the diameter of the middle rolls 3 and 4. The minimum diameter of the working roller 2 is about its maximum diameter

to be. As shown in FIG. 3, the ratio between the minimum roller diameter of the working roller 2, the roller diameter of the central backup roller 5 and the roller diameter of both the backup rollers 6 and 7 is (1: 4: 5.2). ), (1: 4.5: 5.2), (1: 4.5: 5.75), (1: 4.22: 6), and (1: 4: 6: 6 :). 4 shows a diagram of the life of a backup roll to obtain the ratio of the roll diameter. The roll life (L _h ) of the backup roll was obtained by the following equation and the conditions given in Tables 1 and 2.

Where N is the number of revolutions of the backup roller

C: Load capacity of backup roll

P: average load of working roller

TABLE 1

TABLE 2

In FIG. 4, the dotted lines a, a 'represent the lifespans of the central backup roller and both end backup rollers 5, 6 and 7 when the working roller 2 is 40 mm, and the virtual lines b, b' When the working roller 2 is 80 mm, the lifespan of the central backup roller and both protein backup rollers 5, 6 and 7 is shown. The method of obtaining the optimum ratio of the roll diameter from the lines a, a 'and b, b' is the same as that disclosed in Japanese Patent Laid-Open No. 57-206507 described above as a prior art.

In the present invention, the solid lines c and c 'shown in FIG. 4 are used without using such a dotted line. In other words, the solid lines c and c 'average the load when the working roller 2 is 40 mm and the load when the working roller 2 is 80 mm to obtain the average load P of the working roller, respectively. The lifetime of the central backup roller and both protein backup rollers (5, 6 and 7) obtained by considering the frequency of use. The lifespan of the central backup roller and the both-sided backup rollers 5, 6 and 7 are made to be the same at the point where the solid lines c and c 'intersect. The diameter ratio between the center and the back-up rolls at both ends is thus determined to be 0.67 to 0.87 as a suitable range for this point. When this range is indicated by the diameter of the smallest working roller as a reference value, that range will be the square range surrounded by the points A, B, C and D in FIG. However, the range enclosed by the triangle DEF is excluded because it is a range that cannot actually be used as a result of the interference between the central backup roller 5 and the both backup rollers 6 and 7.

It should be noted that the present invention is not limited to the above embodiment.

According to the present invention, the life of the backup roller can be the same even if a working roller of a changed diameter is used.

Claims (1)

Each working roll 2 of the upper and lower working rolls for rolling the material 1 to be rolled is supported by three backup rolls 5, 6 and 7 through the middle rolls 3 and 4 of the same diameter. In the high-load 12-stage rolling mill in which the roller diameters of the upper and lower working rollers 2 can be changed at least two kinds, the working rollers 2 having the largest diameter among the roller diameters of the working rollers 2 are provided. The central diameter for simultaneously supporting the roll diameter of the working roller 2 having the minimum diameter and the two middle rollers 3 and 4 is the same as the roller diameter of the middle roller 3,4. The ratio of the roll diameter between the roll diameter of the roll 5 and the roll diameters of both the backup rollers 6 and 7 having the same diameter to support one intermediate roller (3 or 4) (1: 4: 5.2) For heavy loads, characterized by being within the ranges of (1: 4.5: 5.2), (1: 4.5: 5.75), (1: 4.22: 6) and (1: 4: 6) Rolling mill.

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