JP5962418B2 - Lubricating oil supply method in rolling - Google Patents

Description

  The present invention provides a lubricating oil supply capable of reducing uneven wear of a backup roll and suppressing the deterioration of the shape of the passing plate of the steel sheet by rolling the steel sheet in the steel manufacturing process with the minimum amount of lubricating oil supplied. It is about the method.

  A four-high rolling mill composed of a work roll and a backup roll, and a six-high rolling mill further provided with an intermediate roll are widely used for rolling steel sheets. In these rolling mills, the backup roll receives the reaction force of the rolling force applied to the material to be rolled via the work roll or the intermediate roll, and particularly at the edge portion of the material to be rolled with the progress of wear of the work roll. In the vicinity of the contact line with the corresponding position and in the vicinity of the contact line with the edge portion of the intermediate roll due to the intermediate roll shift, in the intermediate roll shift type 6-high rolling mill, the surface receives a strong local pressure. As a result of wear, uneven wear occurs and the service life of the material to be rolled is remarkably impaired.

  Therefore, a lubricant (rolling oil) is supplied and brought into contact with the rolling rolls that contact each other, for example, the contact surface between the work roll and the backup roll, or the contact surface between the intermediate roll and the work roll or the backup roll. While reducing the wear of each roll, suppressing the deterioration of the threading plate shape is performed.

  For example, Patent Document 1 discloses a technique for lubricating a contact portion between a work roll and a backup roll by a rolling oil supply device installed so as to inject the rolling oil toward the backup roll surface. Patent Document 2 discloses a technique for supplying a lubricant between a work roll and a backup roll by limiting a region for supplying the lubricant to a portion near the backup roll that is in contact with the maximum diameter portion of the work roll. Yes.

  Further, Patent Document 3 discloses a method for supplying lubricating oil without using water, in which the lubricating oil is sprayed and supplied to a roll in a mist or granular form together with a non-combustible gas.

  In the technique described in Patent Document 1, emulsion lubrication in which water and lubricating oil are mixed by water injection is used as a lubricant between the work roll and the material to be rolled and between the work roll and the backup roll. However, emulsion lubricants tend to cause dirt in the piping system for supplying lubricant and clogging of nozzles, and in addition to these problems, subtle changes in the viscosity of lubricants due to changes in temperature and humidity. Therefore, there is a problem that the emulsion concentration constantly changes and the lubricating effect varies.

  Further, in the technology for supplying the lubricant limited to the vicinity of the backup roll portion in contact with the maximum diameter portion of the work roll described in Patent Document 2, the maximum of the work roll is always set regardless of the current roll profile of the backup roll. Since the lubricant is supplied in the vicinity of the backup roll that is in contact with the diameter portion, it has been difficult to cope with roll uneven wear and the like that occurs at positions other than the position corresponding to the maximum diameter portion of the work roll.

  Furthermore, the technique described in Patent Document 3 is a method in which the lubricating oil is not mixed with water and is granulated by an air atomizing method or the like and sprayed onto the roll surface to reduce the supply amount of the lubricating oil and slip. Although the rolling operation can be performed under the condition that the lubrication effect can be obtained within a range not causing the occurrence of rolls, no countermeasures against roll uneven wear or the like have been taken.

JP 2006-110555 A JP 2009-208087 A JP 2003-94104 A

  The above-described prior art is intended to reduce roll wear while suppressing biting failure due to slip between rolls by supplying a necessary and sufficient amount of lubricant to a predetermined position. However, the present invention suppresses uneven wear of the backup roll without causing slippage between the work roll or the intermediate roll and the backup roll by supplying the minimum amount of lubricating oil to an appropriate part. The purpose is to improve the operational stability by ensuring the passage of the material to be rolled and extending the life of the backup roll.

  In view of the above problems, the present invention provides a method for supplying lubricating oil to the contact portion between the upper and lower work rolls and the upper and lower backup rolls using the air atomization method, and the profile or roll width of the backup roll measured during work roll recombination. Specify the uneven wear part of the backup roll based on the direction load prediction, etc., and limit the area to supply the lubricant to the uneven wear area of the backup roll among the contact parts between the upper and lower work rolls and the upper and lower backup rolls. Thus, it is possible to suppress the partial wear of the backup roll without causing slip at the roll contact portion, and the gist thereof is as follows.

(1) In the lubricating oil supply method in rolling in which steel is rolled by a four-high rolling mill, the uneven wear region of the backup roll is specified, and the region for supplying the lubricant is limited to the uneven wear region of the backup roll, When injecting and supplying to the contact part between the upper and lower work rolls and the upper and lower backup rolls together with nonflammable gas without mixing with water ,
The parameters related to the uneven wear area of the backup roll are the minimum radius a and the maximum radius b of the backup roll and values of x = 20 to 800, and when a ≦ b−x (μm) is satisfied, lubricating oil is supplied. A lubricating oil supply method characterized in that the region is limited to a region having a radius r within a range of a ≦ r ≦ b−x (μm) in the body length direction of the backup roll .

( 2 ) In the lubricating oil supply method, the lubricating oil supply amount is 0.01 cc or more and 30 cc or less per 1 m ^{2 of the} roll surface area, and the kinematic viscosity at 40 ° C. is 800 cSt or less in a granular state with an average particle diameter of 5 mm or less. The lubricating oil supply method according to (1 ) above, wherein the lubricating oil is supplied together with a non-combustible gas having an injection speed of 1 m / second or more without being mixed with water.

( 3 ) In the lubricating oil supply method in rolling in which the steel material is rolled by a 6-high rolling mill, the uneven wear region of the backup roll is specified, and the region for supplying the lubricant is limited to the uneven wear region of the backup roll, When injecting and supplying to the contact part between the upper and lower intermediate rolls and the upper and lower backup rolls together with nonflammable gas without mixing with water ,
In the lubricating oil supply method, the parameters relating to the uneven wear area of the backup roll are the minimum radius a and the maximum radius b of the backup roll and numerical values x = 20 to 800, and a ≦ b−x (μm) is satisfied. And a region for supplying the lubricating oil is limited to a region having a radius r in the range of a ≦ r ≦ b−x (μm) in the body length direction of the backup roll .

( 4 ) In the lubricating oil supply method, the lubricating oil supply amount is 0.01 cc or more and 30 cc or less per 1 m ^{2 of} roll surface area, and the kinematic viscosity at 40 ° C. is 800 cSt or less in a granular state with an average particle diameter of 5 mm or less. Then, the lubricating oil supply method according to ( 3) above, wherein the lubricating oil is supplied together with a non-combustible gas having an injection speed of 1 m / second or more without being mixed with water.

( 5 ) In the lubricating oil supply method in rolling in which the steel material is rolled by a six-high rolling mill, the uneven wear region of the intermediate roll is specified, and the region for supplying the lubricant is limited to the uneven wear region of the intermediate roll, When injecting and supplying to the contact part between the upper and lower work rolls and the upper and lower intermediate rolls together with nonflammable gas without mixing with water ,
The parameters related to the uneven wear area of the intermediate roll are the minimum radius a and maximum radius b of the intermediate roll and numerical values x = 20 to 800, and when a ≦ b−x (μm) is satisfied, the lubricating oil is supplied. A lubricating oil supply method characterized in that the region is limited to a region having a radius r within a range of a ≦ r ≦ b−x (μm) in the body length direction of the intermediate roll .

( 6 ) In the lubricating oil supply method, the lubricating oil supply amount is 0.01 cc or more and 30 cc or less per 1 m ^{2 of the} roll surface area, and the kinematic viscosity at 40 ° C. is 800 cSt or less in a granular state with an average particle diameter of 5 mm or less. Then, the lubricating oil supply method according to ( 5) above, wherein the lubricating oil is supplied together with a non-combustible gas having an injection speed of 1 m or more per second without being mixed with water.

( 7 ) Separately from the lubricant injected together with the nonflammable gas, the emulsion lubricant is transferred from the separate nozzle to the upper and lower work rolls and the upper and lower backups when there is no uneven wear on the backup roll and / or the intermediate roll. From said (1) characterized by supplying to any one or more of a contact part with a roll, a contact part of an upper and lower intermediate roll and an upper and lower backup roll, or a contact part of an upper and lower work roll and an upper and lower intermediate roll ( 6 ) The lubricating oil supply method according to any one of ( 6 ).

  In the present invention, the backup roll uneven wear from the measured value of the backup roll profile obtained at the time of work roll recombination, or from the wear distribution of the backup roll calculated from the contact load distribution between the work roll and the intermediate roll in contact with the backup roll. By identifying the area and supplying the required minimum amount of lubricating oil only to the required part, it is possible to reliably suppress the progress of uneven wear of the backup roll, and excessive lubricating oil is supplied. It is difficult to slip on the contact surface between the work roll or intermediate roll and the backup roll due to the fact that the material to be rolled can be passed through reliably, and uneven wear of the backup roll is suppressed. The backup roll profile is maintained even at the later stage of the deadline, or Combined with the frequency of Ppuroru replacement can be reduced, a large contribution to improve the stability of the operation.

It is a side view of the 4-high rolling mill to which the lubricating oil supply method concerning the present invention is applied. It is a conceptual diagram of the position of a backup roll axial direction and the position which supplies lubricating oil. It is a figure showing the profile change of the backup roll, the upper is the difference in the wear profile of the backup roll before and after use when the lubricating oil supply method according to the present invention is not applied, and the lower is when the method of the present invention is applied Indicates. It is an example which shows the profile and lubrication range of a backup roll axial direction. It is an example which shows the profile and lubrication range of a backup roll axial direction. It is an example which shows the profile and lubrication range of a backup roll axial direction. It is an example which shows the profile and lubrication range of a backup roll axial direction.

Embodiments of the present invention will be described below.
As is well known, the four-high rolling mill shown in FIG. 1 includes upper and lower work rolls 1 and 1 and upper and lower backup rolls 2 and 2, a contact surface between the upper work roll and the upper backup roll, a lower work roll and a lower backup. Lubricating oil supply nozzles 5 are arranged at predetermined intervals in the axial direction toward the contact surface with the roll.

  Further, a stylus type profile meter 4 is provided so that the surface of the upper and lower backup rolls 2 can be scanned in the axial direction. The profile meter 4 may be of a stylus type or another type such as an optical type. In any case, the profile meter 4 is installed so as to be retractable from the measurement position when the rolling mill is in operation.

  When the rolling mill is in operation and the time for replacing the work roll 1 is reached, the profile meter 4 is moved from the retracted position to the measuring position, and the upper and lower backup rolls 2 are scanned in the axial direction so Know the wear situation.

  The backup roll 2 receives a rolling reaction force from the material to be rolled via the work roll 1 and usually tends to increase the amount of wear at the position corresponding to the edge portion of the material to be rolled. Since the material to be rolled is rolled according to the production schedule, the wear state varies depending on the number and order of the products to be produced.

  After the wear state of the upper and lower backup rolls 2 is grasped by the profile meter 4, a predetermined amount of lubricating oil is supplied from the lubricating oil supply nozzle 5 to a portion where wear is progressing during the subsequent operation. Injects and suppresses the progress of wear.

  The lubricating oil supply nozzle 5 is installed toward the contact surface between the work roll 1 and the backup roll 2, and has a small diffusion in the roll axis direction. It is preferable that the target position accuracy in the sheet width direction) can be increased.

  A plurality of lubricating oil supply nozzles 5 are provided in each of the upper and lower backup rolls 2 in the roll axial direction (in the sheet width direction of the material to be rolled), and a necessary amount of lubricating oil is supplied from each nozzle. A separate lubricating oil supply nozzle capable of supplying different lubricating oils may be provided so as to be movable in the roll axis direction, and may be supplied to a specific portion of the roll surface as necessary. A separate lubricating oil supply nozzle capable of supplying emulsion lubricating oil is provided in the roll axis direction, and emulsion lubricating oil can be supplied toward the contact surface between the work roll and the backup roll when uneven wear of the backup roll does not occur You may do it.

The region where the lubricating oil is supplied is basically, for example, the entire portion from the radius region that is about 20 μm smaller than the maximum radius of the backup roll to the minimum radius region, but the influence on the shape of the material to be rolled, Depending on the characteristics of the profile or the remaining expected roll life, the roll profile can be reduced by further restricting the supply area of the lubricating oil by making the region from the radius smaller than 30 to 800 μm or more to the minimum radius as a lubrication region. The roll profile may be smoothed by relatively speeding up wear of the large-diameter portion.
That is, in a ≦ r ≦ b−x (μm), x can be determined from a numerical value of 20 to 800. Since uneven wear in which the difference between the maximum radius and the minimum radius of the backup roll is less than 20 μm is difficult to detect with a profile meter, x is set to 20 or more. On the other hand, if uneven wear occurs in which the difference between the maximum radius and the minimum radius of the backup roll is larger than 800 μm, normal threading becomes impossible due to deterioration of the threading shape, so x is set to 800 or less.

  FIG. 2 shows a conceptual diagram of the profile in the axial direction of the backup roll and the position where the lubricating oil is supplied. In FIG. 2, lubricating oil that is not mixed with water is injected and supplied together with a nonflammable gas into a region from a position smaller than the maximum radius b by 20 μm or more to a minimum radius a.

About the supply amount of lubricating oil to be used, if the value is too low, the effect of suppressing roll uneven wear cannot be sufficiently obtained, but if the value is too large, the effect of suppressing roll uneven wear cannot be seen. It was set to 0.01 cc or more and 30 cc or less per 1 m ^{2 of} roll surface area. If the kinematic viscosity of the lubricating oil is too high, the lubricating performance will be insufficient, so the range of the kinematic viscosity at 40 ° C. is set to 800 cSt or less. Furthermore, the range of kinematic viscosity at 40 ° C. of the lubricating oil used for rolling is 5 cSt or more, and the range of kinematic viscosity at 40 ° C. is preferably 20 cSt or more when used in hot rolling. Moreover, the size of the lubricating oil was set to a particle size of 5 mm or less so that the falling from the roll surface was suppressed and the adhesion to the roll surface was facilitated. Furthermore, by supplying non-combustible gas (for example, air, helium, nitrogen, argon, etc.) at an injection speed of 1 m or more per second, the water and water film on the roll surface that significantly lowers the adhesion efficiency of the lubricating oil is blown off, and the roll Lubricating oil collided and adhered to its own surface.

In FIG. 3, the upper curve shows the difference in the wear profile of the backup roll before and after use when the lubricating oil supply method according to the present invention is not applied, and the lower curve when the method of the present invention is applied.
When uniform lubrication with an emulsion lubricant is adopted before carrying out the present invention, the backup roll surface with which the work roll edge portion comes into contact is greatly worn, whereas the lower stage where the method of the present invention is applied Shows that the progress of wear is suppressed in the uneven wear region where the lubricant is supplied, whereas the wear progresses in the region where the lubricant is not supplied, so that the uneven wear of the portion is greatly reduced. .

  When applied to a rolling method using a six-high rolling mill having an intermediate roll, which is the second embodiment of the present invention, the backup roll 2 is used not only when the work roll is replaced but also when the intermediate roll is replaced. It is only necessary to determine the supply pattern of the lubricating oil by measuring the profile. In this case, the supply position of the lubricating oil is a contact surface between the intermediate roll and the backup roll.

  In the case of a six-high rolling mill, it is obvious that a lubricant supplied in a normal rolling operation may be supplied to the contact surface between the work roll and the intermediate roll. So far, uneven wear suppression of the backup roll has been described. In order to suppress the uneven wear of the intermediate roll, the uneven wear area of the intermediate roll is specified and the intermediate roll and the backup roll or between the work roll and the intermediate roll are identified. The lubricating oil may be supplied only in the uneven wear region of the contact surface.

Further, instead of measuring the backup roll profile with a profile meter, a method of grasping the uneven wear amount of the backup roll from the measured value of the contact load distribution may be used. In this method, the backup is performed after the work roll or the intermediate roll is replaced. A plate material dummy in which a pressure sensor such as a strain gauge is arranged in the contact surface longitudinal direction on the contact surface with the roll is sandwiched between the contact surface between the backup roll and the work roll or the intermediate roll, and a predetermined rolling force is applied, The contact load distribution on the roll contact surface in the roll axis direction is obtained.
Since the work roll or the intermediate roll immediately after replacement is considered to be free of wear, it can be determined that the part with a small measured contact load distribution is an area where the uneven wear of the backup roll is progressing, so in the rolling operation of the next lot Then, lubricating oil may be supplied to the part to suppress uneven wear of the backup roll.

Using a tandem-type four-high rolling mill, emulsion lubrication is performed on the contact surface between the work roll and the backup roll over the entire effective roll length, and slab treatment amount per lot = 50 lots under the condition of 2800 to 3200 t. After rolling the material to be rolled, The backup roll profile was measured with a stylus-type profile meter when the two-stand work roll was changed. The operating conditions for one lot are as follows: rolled steel grade = hot rolled steel strip (SPHC), tandem rolling mill inlet side plate thickness = 25-50 mm, tandem rolling mill outlet side plate thickness = 1.4-4.0 mm, plate width = 900-1200 mm.
As a result, signs of uneven wear were found at positions 500 mm from the left and right end faces of the backup roll having an effective roll length of 2000 mm. In the rolling operation of the next lot, as shown in FIG. 4, the emulsion lubrication was stopped. The rolling operation was performed while supplying 1 cc of lubricating oil per 1 m ² of roll surface area to a region having a radius r in the range of the minimum radius a ≦ r ≦ maximum radius b−300 μm in the body length direction of the backup roll.
As a control example, no. For the 3 stands, emulsion lubrication on the contact surface between the work roll and the backup roll is continued over the entire effective roll length in the next lot without measuring the backup roll profile when replacing the work roll. The rolling operation was performed.

No. 1 which supplied lubricating oil along the method of the present invention. In 2 stands, the uneven wear of the backup roll, which was 600.0 μm when the work roll was replaced, was maintained at 600.0 + 3.0 μm even at the end of rolling of the next lot, and the uneven wear was sufficiently suppressed. In the control example, the uneven wear, which was 600.0 μm when the work roll was changed, increased to 600.0 + 10.0 μm at the end of the next lot.
The effect of reducing uneven wear according to the present invention is as high as 70%, and the backup roll profile maintains a good shape even at the end of the expiration date, and the life can be extended.

Using a tandem type four-high rolling mill, emulsion lubrication is performed on the contact surface between the work roll and the backup roll over the entire effective roll length, and slab treatment amount per lot = 100 lots under the condition of 2800 to 3200 t After rolling the material to be rolled, The backup roll profile was measured with a stylus type profile meter at the time of exchanging the work rolls of 4 stands. The operating conditions for one lot are as follows: rolled steel grade = hot rolled steel strip (SPHC), tandem rolling mill inlet side plate thickness = 25-50 mm, tandem rolling mill outlet side plate thickness = 1.4-4.0 mm, plate width = 900-1200 mm.
As a result, a sign of uneven wear was found at the center position in the width direction of the backup roll having an effective roll length of 2000 mm. Therefore, in the rolling operation of the next lot, as shown in FIG. The rolling operation was performed while supplying 10 cc of lubricating oil per 1 m ² of roll surface area to a region having a radius r in the range of the minimum radius a ≦ r ≦ maximum radius b−800 μm in the body length direction of the backup roll.
As a control example, no. For 5 stands, emulsion lubrication on the contact surface between the work roll and the backup roll is continued over the entire effective roll length in the next lot without measuring the profile of the backup roll when replacing the work roll. The rolling operation was performed.

No. 1 which supplied lubricating oil along the method of the present invention. In 4 stands, the uneven wear of the backup roll, which was 850.0 μm at the time of work roll replacement, was maintained at 850.0 + 8.0 μm even at the end of rolling of the next lot, and the uneven wear was sufficiently suppressed. In the control example, the uneven wear, which was also 820.0 μm when the work roll was changed, increased to 820.0 + 20.0 μm at the end of the next lot.
The effect of reducing uneven wear according to the present invention is as high as 60%, and the backup roll profile maintains a good shape even at the end of the expiration date of use, and the life can be extended.

Using a tandem type 6-high rolling mill, emulsion lubrication is performed on the contact surface between the intermediate roll and the backup roll over the entire length of the effective roll, and the slab processing amount per lot is 25 lots under the condition of 2800 to 3200 t. After rolling the material to be rolled, The backup roll profile was measured with a stylus profile meter when the 6-stand intermediate roll was changed. The operating conditions for one lot are as follows: rolled steel grade = hot rolled steel strip (SPHC), tandem rolling mill inlet side plate thickness = 25-50 mm, tandem rolling mill outlet side plate thickness = 1.4-4.0 mm, plate width = 900-1200 mm.
As a result, a sign of uneven wear was found at a position 250 mm from the drive side end face of the backup roll having an effective roll length of 2000 mm. In the rolling operation after the next lot, as shown in FIG. Then, the rolling operation was performed while supplying 20 cc of lubricating oil per 1 m ² of roll surface area to a region having a radius r in the range of the minimum radius a ≦ r ≦ maximum radius b−20 μm in the body length direction of the backup roll.
As a control example, no. For 7 stands, emulsion lubrication to the contact surface between the intermediate roll and the backup roll over the entire effective roll length is the same as that of the previous lot in the next lot and later without measuring the backup roll profile when replacing the intermediate roll. The rolling operation was continued.

No. 1 which supplied lubricating oil along the method of the present invention. In 6 stands, the uneven wear of the backup roll, which was 150.0 μm at the time of replacing the intermediate roll, was maintained at 150.0 + 5.0 μm even at the time of the next intermediate roll replacement, and the uneven wear was sufficiently suppressed. In the control example, the uneven wear, which was also 160.0 μm at the time of replacing the intermediate roll, increased to 160.0 + 15.0 μm at the time of the next intermediate roll replacement.
The effect of reducing uneven wear according to the present invention is as high as 67%, and the backup roll profile maintains a good shape even at the end of the expiration date of use, and the life can be extended.

Using a tandem type 6-high rolling mill, emulsion lubrication is performed on the contact surface between the work roll and the intermediate roll over the entire effective roll length, and the slab processing amount per lot = 2800-3200t for 5 lots. After rolling the material to be rolled, The intermediate roll profile was measured with a stylus profile meter when the 6-stand work roll was changed.
As a result, since signs of uneven wear were found at a position 400 mm from the work side end face of the intermediate roll having an effective roll length of 2000 mm, the emulsion lubrication was stopped in the rolling operation of the next lot as shown in FIG. The rolling operation is performed while supplying 5 cc of lubricant per 1 m ² of roll surface area to a region having a radius r in the range of the minimum radius a ≦ r ≦ maximum radius b−100 μm in the body length direction of the backup roll. It was.
As a control example, no. For the 7 stands, emulsion lubrication to the contact surface between the work roll and the intermediate roll is performed over the entire effective roll length as in the previous lot, without measuring the profile of the intermediate roll, especially when replacing the work roll. The rolling operation was continued.

No. 1 which supplied lubricating oil along the method of the present invention. In 6 stands, the partial wear of the intermediate roll, which was 300.0 μm at the time of work roll replacement, was maintained at 300.0 + 0.5 μm even at the next work roll replacement, and the partial wear was sufficiently suppressed. In the control example, the uneven wear, which was 305.0 μm at the time of replacing the work roll, increased to 305.0 + 1.4 μm at the time of the next work roll replacement.
The effect of reducing uneven wear according to the present invention is as high as 65%, and the intermediate roll profile maintains a good shape even at the end of the expiration date, and the life can be extended.

  As is clear from the above, according to the lubricating oil supply method of the present invention, the profile of the backup roll is measured when the work roll and / or the intermediate roll is replaced, and a predetermined amount of lubricating oil is supplied to the required position. In addition, the progress of uneven wear of the backup roll can be greatly suppressed, and the roll basic unit in rolling operations can be reduced (increased efficiency) and the amount of lubricant used can be reduced. It can prevent deterioration of the work site environment due to supply, and can reduce the frequency of replacement of backup rolls that require a lot of time and work, contributing greatly to the efficiency of rolling operations. The effect is great.

1 Work roll 2 Backup roll 3 Rolled material 4 Profile meter 5 Lubricating oil supply nozzle

Claims (7)

In a lubricating oil supply method in rolling in which a steel material is rolled by a four-high rolling mill, a non-flammable gas is specified by specifying a partial wear region of the backup roll and limiting a region for supplying the lubricant to the partial wear region of the backup roll. In addition, when spraying and feeding to the contact portion between the upper and lower work rolls and the upper and lower backup rolls ,
The parameters related to the uneven wear area of the backup roll are the minimum radius a and the maximum radius b of the backup roll and values of x = 20 to 800, and when a ≦ b−x (μm) is satisfied, lubricating oil is supplied. A lubricating oil supply method characterized in that the region is limited to a region having a radius r within a range of a ≦ r ≦ b−x (μm) in the body length direction of the backup roll . In the lubricating oil supply method, a lubricating oil supply amount of 0.01 cc to 30 cc per 1 m ^{2 of} roll surface area, a kinematic viscosity at 40 ° C. of 800 cSt or less, in a granular state with an average particle size of 5 mm or less, water The lubricating oil supply method according to claim 1, wherein the lubricating oil is supplied together with a non-combustible gas having an injection speed of 1 m or more per second without mixing. In a lubricating oil supply method in rolling in which steel is rolled by a six-high rolling mill, the uneven wear region of the backup roll is specified, and the region for supplying the lubricant is limited to the uneven wear region of the backup roll and mixed with water. Without incombustible gas, when jetting to the contact portion between the upper and lower intermediate rolls and the upper and lower backup rolls ,
The parameters related to the uneven wear area of the backup roll are the minimum radius a and the maximum radius b of the backup roll and values of x = 20 to 800, and when a ≦ b−x (μm) is satisfied, lubricating oil is supplied. A lubricating oil supply method characterized in that the region is limited to a region having a radius r within a range of a ≦ r ≦ b−x (μm) in the body length direction of the backup roll . In the lubricating oil supply method, a lubricating oil supply amount of 0.01 cc to 30 cc per 1 m ^{2 of} roll surface area, a kinematic viscosity at 40 ° C. of 800 cSt or less, in a granular state with an average particle size of 5 mm or less, water The lubricating oil supply method according to claim 3 , wherein the lubricating oil is supplied together with a non-combustible gas having an injection speed of 1 m or more per second without being mixed. In a lubricating oil supply method in rolling in which steel is rolled by a six-high rolling mill, the uneven wear region of the intermediate roll is specified, and the region where the lubricant is supplied is limited to the uneven wear region of the intermediate roll and mixed with water. Without incombustible gas, without spraying to the contact portion between the upper and lower work rolls and the upper and lower intermediate rolls ,
The parameters related to the uneven wear area of the intermediate roll are the minimum radius a and maximum radius b of the intermediate roll and numerical values x = 20 to 800, and when a ≦ b−x (μm) is satisfied, the lubricating oil is supplied. The lubricating oil supply method according to claim 4, wherein the region is limited to a region having a radius r within a range of a ≦ r ≦ b−x (μm) in the body length direction of the intermediate roll . In the lubricating oil supply method, a lubricating oil supply amount of 0.01 cc to 30 cc per 1 m ^{2 of} roll surface area, a kinematic viscosity at 40 ° C. of 800 cSt or less, in a granular state with an average particle size of 5 mm or less, water The lubricating oil supply method according to claim 5 , wherein the lubricating oil is supplied together with a non-combustible gas having an injection speed of 1 m or more per second without being mixed. Separately from the lubricating oil injected together with the non-flammable gas, when uneven wear has not occurred in the backup roll and / or the intermediate roll, the emulsion lubricating oil is supplied from the separate nozzle to the upper and lower work rolls and the upper and lower backup rolls. contact portion, the contact portion between the upper and lower intermediate rolls as the upper and lower backup rolls, or any one of claim 1, wherein 6 to supply more than any one point of the contact portion between the upper and lower work rolls and upper and lower intermediate rolls The lubricating oil supply method according to Item 1.

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