JP2010014135A - Rolling bearing for backup roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a structure reducing maintenance cost of a rolling bearing and lengthening the service life by inexpensively improving durability in an outer peripheral surface of an outer ring. <P>SOLUTION: This rolling bering 8a for a backup roll has an inner ring 9 having an inner ring track 17 on the outer peripheral surface and fitted around and fixed to a support shaft for supporting the backup roll of a metal rolling machine, an outer ring 10a having an outer ring track 20 on an inner peripheral surface, and a plurality of rolling elements 12 rollingly arranged between these inner ring track 17 and outer ring track 20. A DLC coating film 22 is formed on the outer peripheral surface 11a of the outer ring 8a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rolling bearing which is assembled to a support shaft for supporting a backup roll of a metal rolling mill for rolling a metal material containing iron and non-ferrous metals, and uses an outer peripheral surface of an outer ring as a roll surface of the backup roll. Regarding improvements.

As a metal rolling mill for rolling a metal material, a multi-stage metal rolling mill called a so-called Sendzimir rolling mill described in Patent Document 1 or the like has been conventionally used. FIG. 2 schematically shows the structure of this multi-stage metal rolling mill.
This multi-stage metal rolling mill 1 includes a pair of work rolls 2, 2, four first intermediate rolls 3, 3, six second intermediate rolls 4, 4, and eight backup rolls 5, 5. It consists of.
Both of these work rolls 2 and 2 directly process the metal material 24 to be rolled as shown by the chain line in FIG. 2, and are arranged at positions sandwiching the metal material 24 from the vertical direction of FIG. is doing.
The four first intermediate rolls 3 and 3 support the work rolls 2 and 2 with two first intermediate rolls 3 and 3 sandwiched from above and below in FIG. Arranged.
In addition, the six second intermediate rolls 4, 4 are in a state where the first intermediate rolls 3, 3 are sandwiched from the vertical direction of FIG. 2 by three second intermediate rolls 4, 4. Arranged to support.
Further, the eight backup rolls 5, 5 are supported by the four backup rolls 5, 5 so that the second intermediate rolls 4, 4 are sandwiched from above and below in FIG. 2. It is arranged. Each of the backup rolls 5 and 5 includes a support shaft (not shown) for rotatably supporting the backup rolls 5 and 5 with respect to a fixed part such as a housing, and shafts of the support shafts. It comprises a plurality of rolling bearings assembled so as to be adjacent to each other in the axial direction at the middle portion in the direction. Moreover, the outer peripheral surface of the outer ring | wheel of each of these rolling bearings has comprised each backup roll surface 6 and 6 of each said backup roll 5 and 5 in the state integrated in this way.

FIG. 3 shows the structure of a rolling bearing 8 for each of the backup rolls 5 and 5 that has been conventionally known. The rolling bearing 8 includes a plurality of cylindrical rollers 12 and 12 each of which is a rolling element, and a cage 13 between the outer peripheral surface of the inner ring 9 and the inner peripheral surface of the outer ring 10 that are arranged concentrically with each other. Arranged.
The inner ring 9 is formed by combining a cylindrical member 14 and a pair of annular flange members 15 and 15 disposed at both ends of the cylindrical member 14 in the axial direction (left and right direction in FIG. 3). In a state where these members are combined in this way, the inner peripheral surfaces of the cylindrical member 14 and the two annular ring flange members 15, 15 are attached to the support shafts 16 of the backup rolls 5, 5 (see FIG. 2). A cylindrical concave surface is used for external fitting. Further, an inner ring raceway 17 that is a cylindrical convex surface is formed at the axially central portion of the outer peripheral surface of the inner ring 9 (the outer peripheral surface of the cylindrical member 14). Further, outward flanges 19 and 19 each having an outward flange shape are formed on both ends in the axial direction of the inner ring 9 (outside of the outer circumferential surface of the cylindrical member 14 of the two annular ring-shaped flange members 15 and 15, respectively). A protruding part) is provided. In addition, an oil passage hole 23 that penetrates the inner ring 9 in the radial direction is provided in an axially central part of the inner ring 9 (axial central part of the cylindrical member 14).
Further, the outer ring 10 is formed with outer ring raceways 20 and 20 which are a pair of cylindrical concave surfaces facing the inner ring raceway 17 on both sides in the axial direction of the inner peripheral surface. A shaped inward flange 21 is provided. The outer peripheral surface 11 of the outer ring 10 is a cylindrical convex surface.
Further, a plurality of cylindrical rollers 12 and 12 are provided between the inner ring raceway 17 and the outer ring raceways 20 and 20, respectively, so as to roll freely for each row.
The cage 13 holds the cylindrical rollers 12 and 12 so that they can roll.

The backup roll rolling bearing 8 configured as described above includes a plurality of rolling bearings 8 at a plurality of locations in the axial direction of the support shafts 16 of the backup rolls 5 and 5 and the inner rings 9 of the respective rolling bearings 8 disposed outside. Assemble by fixing. In this assembled state, the outer peripheral surface 11 of the outer ring 10 of each of the rolling bearings 8 forming the backup roll surfaces 6 and 6 of the respective backup rolls 5 and 5 is, as shown in FIG. Rolling contact with each of the second intermediate roll surfaces 7 and 7 which are outer peripheral surfaces of the rolls 4 and 4 causes a high load (P / C = 0.5 or more, which is a ratio of the dynamic equivalent load P and the basic dynamic load rating C). Load). For this reason, normally, the strength and rigidity of the outer ring 10 are increased by increasing the thickness of the outer ring 10 in the radial direction (vertical direction in FIG. 3).
However, even if the strength and rigidity of the outer ring 10 are secured by the method described above, the backup roll surfaces 6 and 6 (the outer peripheral surface 11 of the outer ring 10) and the second intermediate roll surfaces 7 and 7 It is conceivable that damage such as wear occurs in the contact portion. Such damage lowers the surface accuracy of the backup roll surfaces 6 and 6 (the outer peripheral surface 11 of the outer ring 10), thereby reducing the function of the backup rolls 5 and 5. Therefore, when the outer peripheral surface 11 of the outer ring 10 is damaged, the outer peripheral surface 11 is subjected to regrind (re-grinding) for recovering the surface accuracy, and the rolling bearing 8 is reused. Since this regrind method has been widely known from the prior art as described in Patent Document 2, detailed description thereof is omitted.

The life of the rolling bearing 8 is determined by the amount by which the outer diameter of the outer ring 10 is reduced by repeating the regrind. When the durability of the outer peripheral surface 11 of the outer ring 10 of the rolling bearing 8 is low and the outer peripheral surface 11 is likely to be damaged, the regrind frequency is increased, and the outer diameter of the outer ring 10 is reduced. The life of the rolling bearing 8 is shortened.
Moreover, the conventionally known regrind as described in Patent Document 2 requires time-consuming work. For this reason, as described above, the outer peripheral surface 11 of the outer ring 10 of the rolling bearing 8 is likely to be damaged, and when the frequency of the regrind increases, the maintenance cost of the rolling bearing 8 and thus the multi-stage metal rolling mill. The maintenance cost of 1 will increase.

  Therefore, Patent Document 3 describes an invention for improving the durability of the outer peripheral surface of the outer ring constituting the backup roller rolling bearing. In the invention described in Patent Document 3, the outer ring constituting the rolling bearing is made of an iron-based alloy in which the contents of C, Si, and Mn are regulated within a predetermined range. In addition, after producing a work piece processed into this material, the work piece is subjected to heat treatment including carburizing or carbonitriding to regulate the C content of the outer peripheral surface of the outer ring within a predetermined range. To do. In the case of such a rolling bearing for a backup roll described in Patent Document 3, it is possible to increase the strength of the outer peripheral surface of the outer ring to improve the durability of the outer peripheral surface and to reduce the frequency of the regrind. it can. For this reason, the maintenance cost of the rolling bearing can be reduced and the life can be extended. However, in the case of the rolling bearing described in Patent Document 3, since a special material whose component is adjusted to a predetermined value is used, the procurement cost of the material may increase. Moreover, since the heat treatment for increasing the strength of the outer peripheral surface requires a plurality of processing steps, the processing cost may be increased.

JP 2001-259721 A Japanese Patent Laid-Open No. 9-207053 JP 2002-194438 A

  In view of the circumstances as described above, the present invention aims to improve the durability of the outer peripheral surface of the outer ring constituting the rolling bearing for the backup roll at a low cost, and to reduce the maintenance cost and extend the life of the rolling bearing. Invented as much as possible.

A rolling bearing for a backup roll of a metal rolling mill that is an object of the present invention includes an inner ring, an outer ring, and a plurality of rolling elements.
Of these, the inner ring has an inner ring raceway on the outer peripheral surface, and is fitted and fixed to a support shaft that supports a backup roll of a metal rolling mill.
The outer ring has an outer ring raceway on the inner peripheral surface.
Each of the rolling elements is provided between the inner ring raceway and the outer ring raceway so as to roll freely.
In particular, in the rolling bearing for backup roll of the present invention, a DLC (Diamond Like Carbon) film is formed on the outer peripheral surface of the outer ring.

As described above, the rolling bearing for a backup roll of the present invention has a DLC film formed on the outer peripheral surface of the outer ring, and the durability of the outer peripheral surface of the outer ring is greatly improved. For this reason, the frequency of regrinding to reduce the outer diameter of the outer ring is reduced, the maintenance cost of the rolling bearing can be reduced, and the life of the rolling bearing can be extended.
The material of the outer ring of the rolling bearing may be a material used for an outer ring of a general bearing such as high carbon chromium bearing steel class 2 (SUJ2). For this reason, even if it compares with a general outer ring | wheel, material cost does not increase.
Further, the DLC film can be formed by a conventionally known formation method such as a CVD method (chemical vapor deposition method) or a PVD method (physical vapor deposition method) that has been widely known. If the DLC film is formed by such a forming method, the durability of the outer peripheral surface of the outer ring can be remarkably improved with fewer processing steps than the method described in Patent Document 3. For this reason, the processing cost and the frequency of regrind can be greatly reduced.

  FIG. 1 shows an example of an embodiment of the present invention. The feature of the present invention, including the present example, is that this backup roll rolling bearing 8a is provided in order to realize a structure capable of reducing the maintenance cost and extending the life of the backup roll rolling bearing 8a at a low cost. It is in the point which devised the property of the outer ring | wheel 10a to comprise. Since the structure and operation of the other parts are the same as those of the rolling bearing 8 having the conventional structure shown in FIG. 3, the same parts are denoted by the same reference numerals, and redundant description is omitted or simplified. The description will focus on the characteristic part.

The outer ring 10a constituting the rolling bearing 8a for the backup roll of this example has a DLC film 22 formed on the outer peripheral surface 11a. The DLC film 22 is formed by a forming method such as a CVD method or a PVD method. Since each of these forming methods has been widely known in the past, detailed description thereof will be omitted.
In the rolling bearing 8a, a plurality of rolling bearings 8a are externally fitted and fixed to a plurality of axial directions of the support shaft 16 constituting the backup rolls 5 and 5 (see FIG. 2). Assemble by. Further, in this assembled state, the outer peripheral surface 11a of the outer ring 10a of each rolling bearing 8a forms the backup roll surfaces 6 and 6 (see FIG. 2) of the backup rolls 5 and 5, respectively. The backup roll surfaces 6 and 6 (the outer peripheral surface 11a of the outer ring 10a) are the outer peripheral surfaces of the second intermediate rolls 4 and 4 constituting the multi-stage metal rolling mill 1, as shown in FIG. A high load is applied by rolling contact with certain second intermediate roll surfaces 7 and 7.

In the case of the rolling bearing 8a of this example, the DLC film 22 is formed on the outer peripheral surface 11a of the outer ring 10a of the rolling bearing 8a to improve the durability (wear resistance) of the outer peripheral surface 11a. Yes. For this reason, even if each said backup roll surface 6 and 6 (outer peripheral surface 11a of the said outer ring | wheel 10a) as mentioned above is used in the state which loads high load, these each backup roll surface 6 and 6 are hard to produce damage. it can.
Thus, if the effect of preventing damage to the outer peripheral surface 11a of the outer ring 10a is improved, the frequency of regrind can be reduced, and the maintenance cost can be reduced. Furthermore, the outer diameter of the outer ring 10a can be delayed to extend the life of the rolling bearing 8a.
Further, since the material of the outer ring 10a of the rolling bearing 8a is a material used for an outer ring of a general bearing such as bearing steel such as high-carbon chromium bearing steel class 2 (SUJ2), the material cost increases. There is nothing.
The DLC film can be formed by a conventionally well-known formation method such as a CVD method or a PVD method. When the DLC film is formed by such a forming method, the durability of the outer peripheral surface 11a of the outer ring 10a can be improved with fewer processing steps than the method described in Patent Document 3. For this reason, the processing cost can be reduced.

The present invention is not limited to the backup rolls 5 and 5 of the multi-stage metal rolling mill 1, but is used in a state where the outer peripheral surface of the outer ring is loaded with a high load and the outer peripheral surface is desired to be prevented from being damaged. If applied, the same effect can be obtained.
Further, the present invention is not limited to the structure of the rolling bearing of one example of the above embodiment, and can be applied to various rolling bearings.
In addition, the hardness of the outer peripheral surface of the outer ring of the rolling bearing of the present invention on which the DLC film is formed is very high. For this reason, when foreign matter is mixed between the backup roll surface of the backup roll of the multistage metal rolling mill (the outer peripheral surface of the outer ring) and the outer peripheral surface of each intermediate roll during use, indentations are formed on the outer peripheral surfaces of these intermediate rolls. There is a possibility that the indentation may be transferred to the metal material through each work roll of the multi-stage metal rolling mill. For this reason, it is preferable to use this invention as a backup roll of the multistage metal rolling mill which rolls an electromagnetic steel plate etc. in which the high surface precision is not calculated | required. However, if measures such as provision of the above foreign matter are provided, it can be used even when high surface accuracy is required.

The partial sectional view of the rolling bearing for backup rolls which shows one example of an embodiment of the invention. The schematic diagram which shows the structure of the multistage metal rolling mill of the conventional structure. The fragmentary sectional view which shows an example of the rolling bearing for backup rolls of the conventional structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multistage metal rolling mill 2 Work roll 3 Intermediate roll 4 Second intermediate roll 5 Backup roll 6 Backup roll surface 7 Second intermediate roll surface 8, 8a Rolling bearing 9 Inner ring 10, 10a Outer ring 11, 11a Outer peripheral surface 12 Cylindrical roller 13 Holding Device 14 Cylindrical member 15 Ring-shaped saddle member 16 Support shaft 17 Inner ring raceway 18 Step part 19 Outward saddle part 20 Outer ring raceway 21 Inward saddle part
22 DLC coating 23 Oil passage hole 24 Metal material

Claims (1)

  An outer ring having an inner ring raceway on the outer peripheral surface and fitted and fixed to a support shaft that supports a backup roll of a metal rolling mill, an outer ring having an outer ring raceway on the inner peripheral surface, and between the outer ring raceway and the inner ring raceway A backup roll rolling bearing comprising a plurality of rolling elements provided in a freely rollable manner, wherein a DLC film is formed on the outer peripheral surface of the outer ring.

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