JP6651986B2 - Lubricating oil supply method in hot rolling - Google Patents

Description

  The present invention relates to a lubricating oil supply method used when hot rolling a metal material such as steel, and in particular, in hot rolling of a section steel such as an H-section steel, a section steel, a steel sheet, etc., a part of a roll. And a local lubrication supply method for supplying lubricating oil intensively to a vehicle.

  Emulsion lubrication and gas atomization lubrication are known as lubricating oil supply methods in hot rolling of steel materials and the like. The emulsion lubrication method is a method of lubricating by supplying a fluid (emulsion) formed by forcibly mixing a small amount of lubricating oil and water by mechanical stirring, and is generally used as a hot rolling lubrication method. Widespread. On the other hand, the gas atomizing lubrication method is a method in which a stock oil of lubricating oil is atomized with a non-flammable gas such as air using a gas-liquid two-fluid nozzle, and is supplied to the roll surface together with the non-flammable gas in a finely divided state ( See, for example, Patent Document 1. It is known that the latter gas atomizing lubrication method can exert a lubricating effect equal to or higher than that of the emulsion lubrication method with a small amount of lubricating oil.

  In lubrication of a rolling roll of a hot rolling mill, if lubricating oil is excessively supplied, a phenomenon (slip trouble) in which a material to be rolled slips on the rolling roll is likely to occur. For example, when a non-rolled material is bitten by a roll bite, a phenomenon in which the material to be rolled slips against a rolling roll and is not bitten smoothly (biting slip), or a slip during rolling is likely to occur. On the other hand, if the supply amount of the lubricating oil is too small, it becomes difficult to achieve the original purpose of the lubrication, that is, to prevent the wear and seizure of the roll. Therefore, in general, the lubricating oil supply amount is adjusted so as not to cause an excessive supply within a range in which abrasion and seizure of the roll can be suppressed.

  By the way, the place where the abrasion or seizure of the roll occurs during the hot rolling is often a part of the area where the roll and the material to be rolled come into contact with each other. 1, a steel sheet pile 2 as shown in FIG. 8, a section steel such as a channel steel 3 as shown in FIG. 9, a rail steel 4 as shown in FIG. In other words, in hot rolling for obtaining a steel product having a bent portion (curved or bent portion) in a cross section orthogonal to the length direction, the roll is worn or burned at a position in contact with the surface of the bent portion. Sticking is easy to occur. For example, in the H-section steel 1 shown in FIG. 7, there are continuous portions 1D and 1E which rise / fall at substantially right angles from the web portion 1A toward the flange portions 1B and 1C. The surfaces of such continuous portions 1D and 1E Each has a portion (surface curved portion) 1F that bends in a 90-degree direction with a relatively small curvature. In such hot rolling of the H-section steel 1, abrasion and seizure of the roll are likely to occur near the portion of the roll surface that comes into contact with the above-mentioned surface curved portion 1F. Local seizure may also occur in a portion where the contact pressure is locally increased due to a decrease in the temperature of the steel plate, such as an edge portion of the steel plate.

FIG. 11 schematically shows a state of hot rolling by a universal mill for a specific H-section steel (a state viewed from the rolling mill exit side).
In FIG. 11, the material to be rolled 10 is rolled by a pair of left and right vertical rolls 12A and 12B rotating about a vertical axis 0V and a pair of upper and lower horizontal rolls 13A and 13B rotating about a horizontal axis OH. , Formed into an H-shaped cross-section to form an H-shaped steel 1. At this time, on the surfaces of the horizontal rolls 13A and 13B, the webs 1A of the H-shaped steel rise and stand toward the flanges 1B and 1C. In the area that comes into contact with the curved portion 1F on the surfaces of the continuous portions 1D and 1E, that is, the corner portions 15A and 15B at both ends in the direction along the roll axis OH of the horizontal rolls 13A and 13B, the material to be rolled and the roll surface Since a large friction acts between the rolls, abrasion and seizure of the roll are likely to occur. On the other hand, in other portions, for example, a portion (intermediate portion) 15C between the corner portions 15A and 15B for rolling the material to be rolled into a flat shape, roll abrasion and seizure are relatively unlikely to occur. .

Therefore, in hot rolling of shaped steel and rail steel, lubricating oil is intensively supplied to the parts where roll wear and seizure are likely to occur, especially at the corners, to suppress roll wear and seizure. However, lubricating oil is not supplied to other parts without lubricating oil, or lubricating oil is supplied to the extent that no lubricating effect is exhibited. It is desired to perform an operation by so-called local lubrication, which minimizes the risk of causing air pollution.
For example, in the rolling of the H-section steel by the universal rolling mill shown in FIG. 11, lubricating oil is supplied only to the corner portions 15A and 15B of the horizontal rolls 13A and 13B, and lubricating oil is supplied to other regions, for example, the intermediate portion 15C. It is desired to perform hot rolling without supplying.

  However, among the conventional roll lubrication methods applied to hot rolling, the emulsion lubrication method requires a large amount of emulsion fluid to be supplied from a nozzle to the roll, so that only a part of the roll has sufficient lubrication locally. It is difficult to supply a required amount of lubricating oil that can exert an effect.

  On the other hand, in the gas atomizing lubrication method, it is not impossible to locally supply a necessary amount of lubricating oil only to a part of the roll, but the gas sprayed together with the lubricating oil causes the lubricating oil adhering to the roll surface to lose lubricating oil Therefore, it is difficult to supply the lubricating oil only to the intended portion. That is, when the lubricating oil adheres to the roll surface, or thereafter, the lubricating oil adheres to the roll surface due to the centrifugal force due to the rotation of the roll, the gas flow from the nozzle when the lubricating oil is sprayed and supplied, or the accompanying flow. Tends to spread outside the intended supply area. For this reason, it has been difficult to secure the friction coefficient in the lubricating oil non-supplying area (non-lubricating area) outside the intended lubricating oil supply area and to reliably prevent the occurrence of slip trouble.

  Therefore, in the past, the local lubrication method was sometimes performed by a method in which a solid lubricant such as wax was pressed against a roll, but in this case, it was difficult to control the supply amount of the wax, and radiant heat from the steel material was used. There is also a problem that the wax is melted, so that it has not been put to practical use, and it has been difficult to sufficiently and exclusively lubricate only the region to be lubricated as described above. Therefore, when hot rolling a steel material having a surface curved portion such as the aforementioned H-section steel, the supply of lubricating oil to the surface curved portion, that is, a portion where roll wear or seizure is likely to occur is insufficient. As a result, it is difficult to reliably suppress the abrasion and seizure of the roll, or conversely, it is difficult to reliably prevent the occurrence of slip trouble.

The technique proposed in Patent Document 1 is a gas atomizing lubrication method in which a lubricating oil stock having a kinematic viscosity of 800 cSt or less is used at 0.01 to 30 cc / m ² , the average particle diameter of oil droplets is 5 mm or less, and 1000 cc or more per minute. This technique makes it possible to carry out substantially uniform lubrication rolling over the entire length of the material to be rolled by injecting and supplying the gas to the roll together with the gas having a flow rate of, and does not intend the local lubrication method as described above.

JP-A-2003-94104

  The present invention has been made in view of the above circumstances, and when the gas atomizing lubrication method is used to locally supply the lubricating oil only to a partial area of the roll surface, the lubricating oil may spread to areas other than the intended area. To achieve the effect of local lubrication reliably, that is, the effect of reliably suppressing roll abrasion and seizure in places with high friction during rolling and at the same time reliably suppressing the occurrence of slip trouble. It is an object of the present invention to provide a roll lubrication method that can be used to the maximum extent.

  As a result of repeated experiments and studies conducted by the present inventors to solve the above-mentioned problems, the surface roughness of the rolling roll represented by the maximum height roughness Rz and the amount of lubricating oil supplied per unit area of the rolling roll surface Is set within appropriate ranges, and at the same time, by appropriately adjusting the relationship between the lubricating oil supply amount and the surface roughness, the lubricating oil flows out and spreads outside the intended area (specific area). By supplying a sufficient amount of lubricating oil only to the specific area where seizure and roll wear are likely to occur, a sufficient lubrication effect is obtained in the specific area, and at the same time, slippage occurs due to outflow outside the specific area. The present inventors have found that it is possible to prevent a trouble from easily occurring, and have accomplished the present invention.

Specifically, the lubricating oil supply method in the hot rolling of the basic aspect (first aspect) of the present invention is as follows.
In a state where the lubricating oil is atomized by the non-flammable gas using the gas-liquid two-fluid nozzle, the lubricating oil is locally supplied to a part of a portion of the rolling roll surface that comes into contact with the material to be rolled. In the lubricating oil supply method of a hot rolling mill,
A roll having a maximum height roughness Rz of a portion in contact with the material to be rolled having a maximum height roughness Rz in the range of 0.5 to 50 μm is used. Within the range of 0.5 to 20 cc / m ² ,
The lubricating oil supply amount Q per surface area of the rolling roll is adjusted according to the maximum height roughness Rz such that the ratio Q / Rz between the lubricating oil supply amount Q and the maximum height roughness Rz is 1.2 or less. Set and lubricate ,
The length of the region in the direction along the rolling roll axis direction is 80% or less of the length along the rolling roll axis direction of the entire surface portion in contact with the material to be rolled. .

  Here, the “part of the surface of the rolling roll that comes into contact with the material to be rolled” is a region previously specified as a portion where seizure or roll wear is likely to occur (specification Area). Specifically, for example, a portion that comes into contact with a surface curved portion such as a rising / falling portion from a web portion to a flange portion in an H-section steel is exemplified. Conversely, "supplying lubricating oil locally to a part of the area" means that lubricating oil is not supplied to a part other than the above-mentioned specific area in a part in contact with the material to be rolled. However, since the state in which a very small amount of lubricating oil that hardly exhibits a lubricating effect is supplied is substantially the same as not supplying lubricating oil, for example, the lubricating oil supply amount according to claim 1 In the present invention, a case where a smaller supply amount of lubricating oil is supplied is also included in the present invention.

Further, the lubricating oil supply method in the hot rolling according to the second aspect of the present invention is the method according to the first aspect,
The lubricating oil supply amount Q per surface area of the rolling roll is changed according to the maximum height roughness Rz such that the ratio Q / Rz between the lubricating oil supply amount Q and the maximum height roughness Rz is 1.0 or less. It is characterized by setting and lubricating.

Further, the lubricating oil supply method in the hot rolling according to the third aspect of the present invention is the method according to the first or second aspect,
The lubricating oil has a kinematic viscosity at 40 ° C. in the range of 100 to 800 cSt.

  According to the present invention, the gas atomizing lubrication method is used to locally supply the lubricating oil only to a partial area of the roll surface during hot rolling, and suppresses the lubricating oil from spreading to areas other than the intended area. Thereby, the effect of local lubrication can be reliably obtained, that is, the effect of reliably suppressing roll abrasion and seizure and also reliably suppressing the occurrence of slip trouble can be maximized.

It is a schematic diagram of a rolling mill entrance side main part for explaining an example of a lubricating oil supply area when the lubricating oil supply method of the present invention is applied to hot rolling of an H-section steel by a universal rolling mill. It is a schematic diagram of a main part of a rolling mill entrance side which shows an example of a lubricating oil supply situation when the lubricating oil supply method of the present invention is applied to hot rolling of an H-section steel by a universal rolling mill. FIG. 3 is a schematic view as viewed at the position of line III-III in FIG. 2. FIG. 2 is a schematic diagram of a main part of a rolling mill, showing an implementation state of a model rolling experiment in Example 1. FIG. 4 is a schematic diagram showing a lubricating oil supply state and a lubricating oil adhesion state on a plate after rolling in a model rolling experiment in Example 1. 5 is a graph showing the relationship between the amount of lubricating oil supplied to the lubricating oil adhesion ratio and the surface roughness of a rolling roll as a result of Example 1. It is a schematic diagram which shows the H-section steel as an example of the section steel to which the lubricating oil supply method of this invention is applied by the position of the cross section with respect to the length direction. It is a schematic diagram which shows the steel sheet pile as another example of the shape steel to which the lubricating oil supply method of this invention is applied by the position of the cross section with respect to the length direction. It is a schematic diagram which shows the channel steel as another example of the profile steel to which the lubricating oil supply method of this invention is applied by the position of the cross section with respect to the length direction. It is a schematic diagram which shows an example of the rail steel to which the lubricating oil supply method of this invention is applied by the position of the cross section with respect to the length direction. It is a schematic diagram of the principal part of a rolling mill which shows an example of the situation which rolls an H-beam by a universal rolling mill.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The lubricating oil supply method of the present invention is basically based on the premise that a gas atomizing lubrication method represented by an air atomizing lubrication method is applied as a lubrication method for a rolling roll in a hot rolling mill. That is, as described above, in the emulsion lubrication method, it is difficult to locally limit the lubricating oil supply region, no matter how the lubrication conditions are adjusted, and therefore, using a gas-liquid two-fluid nozzle, It is assumed that the lubricating oil is sprayed and supplied to the roll surface in a state of being atomized by a nonflammable gas such as air or nitrogen gas.

  In the case of the present invention, as a local lubrication method, lubricating oil is locally supplied together with a gas for atomizing only to a part of a portion of the roll surface that comes into contact with the material to be rolled. In other words, of the area on the surface of the rolling roll that comes into contact with the material to be rolled (the area in the direction along the roll axis), a part where the roll is liable to wear or seize (in other words, a part requiring sufficient lubrication) ) Is determined, and the site (a region having a length in the direction along the roll axis direction; a specific region) is specified in advance on the roll surface. The position and orientation of the gas-liquid two-fluid nozzle for atomizing injection, the spread angle of the jet fluid from the nozzle, the roll surface and the nozzle, Set the distance between and the like. Then, in this state, the lubricating oil is injected from the nozzle together with a nonflammable gas such as air.

For example, in the case of hot rolling of an H-section steel by a universal rolling mill, as described with reference to FIG. 11, the horizontal rolls 13A and 13B contacting the surface curved portion 1F continuous from the web portion 1A to the flange portions 1B and 1C. At the corners 15A and 15B, seizure and abrasion of the horizontal roll are likely to occur. Therefore, the roll surface areas in contact with these corner portions 15A, 15B are designated as specific areas 20A, 20B to which the lubricating oil is to be locally supplied, and the atomized lubricating oil is supplied aiming at the specific areas 20A, 20B. . For example, as shown in FIG. 1 in the case of hot rolling of an H-section steel by a universal rolling mill, as shown in FIG. 1, a region including all or a part of the surfaces of the corner portions 15A and 15B of the horizontal rolls 13A and 13B (as described later). horizontal roll 13A, the material to be rolled 10 and horizontal roll 13A in a cross section along the axis OH of 13B, the line segment of the contact portion with 13B, the length _L a, a region) represented by _{L B,} the lubricating oil As the specific regions 20A and 20B to be locally supplied, the atomized lubricating oil is supplied only in the specific regions 20A and 20B.

At this time, as described above, the lubricating oil easily flows out of the range of the specific area (outside the direction along the axial direction of the roll), and particularly in the specific area in order to obtain a sufficient lubricating effect. If the amount of lubricating oil supply per unit area is increased, the tendency becomes remarkable. However, in the present invention, the surface roughness of the portion of the rolling roll that comes into contact with the material to be rolled, and the amount of lubricating oil supplied per unit area to the specific region on the surface of the rolling roll are each regulated within a predetermined range. By adjusting the relationship between the surface roughness and the lubricating oil supply amount within an appropriate range, in other words, by adjusting the lubricating oil supply amount to an appropriate range according to the surface roughness, It is possible to supply a sufficient amount of lubricating oil to suppress seizure and roll wear in the specified area, and to reliably prevent the lubricating oil from flowing out of the specified area. .
Therefore, the reasons for limiting these conditions will now be described.

<Roll surface roughness>
The maximum height roughness Rz, which is the two-dimensional surface roughness of the portion of the rolling roll that comes into contact with the material to be rolled, is expressed by the maximum height roughness Rz defined by JIS B0601, based on the direction along the roll axis direction. , 0.5 to 50 μm. That is, it is necessary to satisfy the following expression (1).
0.5 μm ≦ Rz ≦ 50 μm (1)

  If the maximum height roughness Rz is smaller than 0.5 μm, the lubricating oil sprayed from the nozzles is caused by the gas flow for atomization simultaneously sprayed from the nozzles or its accompanying flow, and the intended specific area on the roll surface. It can easily spread to other places, causing troubles such as rolling slip. On the other hand, when the maximum height roughness Rz is larger than 100 μm, the roll surface roughness is transferred to the surface of the material to be rolled by rolling, and the surface quality of the rolled product may be degraded. Further, when the maximum height roughness Rz is larger than 50 μm, the change in the roughness of the roll during the rolling is increased, and the balance with the initially set lubricating oil supply is changed, and the lubricating oil supply is changed. And the surface roughness may easily deviate from the range defined by the present invention (the range defined by the formula (3) described later), and stable lubricating rolling may not be performed.

<Lubricant supply amount>
It is necessary to set the lubricating oil supply amount Q per unit surface area in the specific region of the rolling roll surface to which lubricating oil is to be supplied, in the range of 0.05 to 20 cc / m ² . That is, it is necessary to satisfy the following expression (2).
0.05 cc / m ² ≦ Q ≦ 20 cc / m ² (2)

If the lubricating oil supply is less than 0.05 cc / m ² , a sufficient lubricating effect such as a roll abrasion suppressing effect and a seizure suppressing effect cannot be obtained irrespective of conditions such as the roll surface roughness. On the other hand, if the supply amount of the lubricating oil is more than 20 cc / m ² , the lubricating oil attached to the roll surface does not burn off in one rotation of the roll, and the lubricating oil gradually accumulates on the roll surface, and the lubricating oil in the intended specific area Even if the amount of the lubricating oil adhered becomes too large and the lubricating oil supply amount itself satisfies the condition of the following formula (3) in relation to the surface roughness, the lubricating oil lubricating oil easily spreads outside the specific region. Could be.

<Relationship between lubricating oil supply and roll surface roughness>
The lubricating oil supply amount Q per unit surface area in a specific area of the rolling roll surface to which lubricating oil is to be supplied, and the maximum height roughness which is a two-dimensional surface roughness of a portion of the rolling roll that comes into contact with the material to be rolled. The relationship with Rz is important for the present invention. That is, after setting the lubricating oil supply amount Q in the range of 0.05 to 20 cc / m ² and the maximum height roughness Rz in the range of 0.5 to 50 μm as described above, When the value of Q / Rz is expressed by the following equation (3),
Q (cc / m ² ) / Rz (μm) ≦ 1.2 (3)
It is important to regulate to satisfy

  Assuming that the expressions (1) and (2) are satisfied, by satisfying the relationship of the expression (3), the lubricating oil adheres only to a specific region of the roll surface under any lubricating oil supply conditions and rolling conditions. It is possible to prevent the lubricating oil supplied as desired from spreading to places other than the specific area.

Here, the lubricating oil supply amount Q (cc / m ² ) per unit area corresponds to the value of the average oil film thickness (μm). If the concave and convex of the roll surface expressed by the maximum height roughness Rz is relatively large with respect to the average oil film thickness, the lubricating oil is more likely to be trapped in the concave portion, and conversely the maximum height If the unevenness of the roll surface expressed by the roughness Rz is relatively small with respect to the average oil film thickness, the lubricating oil flows easily on the roll surface.

  In particular, if the average oil film thickness is 1.2 times or less the maximum height roughness Rz, a large proportion of the lubricating oil adhering to the roll surface is trapped in the recess. When the average oil film thickness exceeds 1.2 times the maximum height roughness Rz, the lubricating oil on the roll surface easily flows over the irregularities. As described above, since the oil film thickness corresponds to the lubricating oil supply amount Q per unit area, the expression (3) expresses the lubricating oil in the concave portion of the unevenness of the roll surface expressed by the maximum height roughness Rz. It means the condition that the lubricant oil is reliably trapped and the flow of the lubricating oil is blocked. If this condition is satisfied, the lubricating oil adhering to the roll surface will It hardly spreads on the surface.

Although the value of Q / Rz is specified to be 1.2 or less in the above equation (3), it is preferably 1.0 or less. That is,
Q (cc / m ² ) / Rz (μm) ≦ 1.0 (3 ′)
It is desirable to adjust the lubricating oil supply amount Q per unit area in accordance with the maximum height roughness Rz so as to satisfy the above. By doing so, it is possible to prevent the lubricating oil from spreading outside the above-described specific region. Can be prevented more reliably.

  Although the lower limit of the value of Q / Rz is not particularly specified, if the value of Q / Rz is extremely small, most of the lubricating oil adhering to the roll surface is present only at the bottom of the concave portion among the unevenness of the roll surface. And a sufficient lubricating effect may not be obtained. From such a viewpoint, the value of Q / Rz is preferably set to 0.2 or more.

As described above, by satisfying the conditions of the expressions (1), (2), and (3) at the same time, the intended purpose can be achieved. It is preferable that the flow velocity V of the non-combustible gas such as air ejected from the gas-liquid two-fluid nozzle be 0.1 m or more and 50 m or less per second as shown by the following equation (4). Further, as the lubricating oil, it is preferable to use a lubricating oil having a kinematic viscosity ν at 40 ° C. of 100 cSt or more and 800 cSt or less as shown in the following formula (5). Further, regarding the range of the region (specific region) where lubricating oil is locally supplied to the surface of the rolling roll, the length L of the line segment where the material to be rolled and the roll come into contact in the cross section of the roll along the roll axis in the specific region for, as shown by the following formula (6), relative to the total length L _t of the line and the material to be rolled and the roll in the cross section are in contact, it is desirable to set to be 80% or less.
These desirable conditions will be described below.

<Gas flow rate>
The velocity V of the non-combustible gas such as air ejected from the gas-liquid two-fluid nozzle for atomizing the lubricating oil may be 0.1 m or more and 50 m or less per second as shown in the following equation (4). preferable.
0,1 m / sec ≦ V ≦ 50 m / sec (4)
If the gas flow rate is less than 0.1 m / s, the lubricating oil injected from the nozzles may be prevented from adhering to the roll surface due to the air flow due to the rotation of the rolling rolls and the scattered cooling water, so that it is sure It may not be possible to obtain a sufficient lubrication effect. On the other hand, if the gas flow rate is higher than 50 m / sec, the force of the non-flammable gas from the nozzle to spread the lubricating oil on the roll surface increases, and as a result, even if the conditions of the above equations (1) to (3) are satisfied. However, the lubricating oil adhering to the roll may spread to places other than the intended specific area, and cause troubles such as rolling slip and bending of the steel material.

<Viscosity of lubricating oil>
As the lubricating oil, it is preferable to use a lubricating oil having a kinematic viscosity ν at 40 ° C. of 100 cSt or more and 800 cSt or less, as shown in the following equation (5).
100 cSt ≦ ν ≦ 800 cSt (5)
A lubricating oil having a kinematic viscosity at 40 ° C. of less than 100 cSt has a small adhesive force to a roll. Therefore, depending on rolling conditions, even if the conditions of the above formulas (1) to (3) are satisfied, the lubricating oil May be difficult to adhere to by limiting the supply area. On the other hand, a lubricating oil having a kinematic viscosity of more than 800 cSt has poor fluidity, so that it may be difficult to smoothly send the lubricating oil from the lubricating oil tank to the nozzle via the pipe, which is not preferable.

<Range of lubricating oil supply area (specific area)>
The length L of a line segment where the material to be rolled and the roll are in contact with each other in the cross section of the roll along the roll axis in the specific region is determined by the following equation (6). to the total length L _t of the line segments, so that 80% or less, it is desirable to set the range of the specific area.
L ≦ 0.8 × L _t (6)
The range of the specific area where the lubricating oil on the surface of the rolling roll should be supplied is determined by the rolled material and the roll when viewed in a roll cross section along the rolling roll axis (a roll cross section along the roll axis direction and including the roll axis). Can be defined by the length of the line segment touching. For example, as shown in FIG. 1 for an example of rolling of an H-section steel, a line segment (contact line) in the cross section of the portion where the material 10 to be rolled contacts the upper horizontal roll 13A in the cross section ) Is _Lt. Then, a region including substantially the entire corner portion 15A on one side of the horizontal roll 13A and a region including substantially the entire corner portion 15B on the other side of the horizontal roll 13A are defined as specific regions 20A to which lubricating oil is to be supplied, respectively. as 20B, expressed these particular regions 20A, each of the length of the contact line in the cross-section of 20B _L a, in _{L B,} both specific region 20A, the contact line length L of the total 20B is a _{[L = L} a + _{L B].} However, since the cross-sectional shape of the H-shaped steel is generally symmetrical, one specific region 20A and the other specific region 20B are generally set in the same range. In this case, L _A = Since L _B , [L = 2 × L _A ].

And in embodiments of the present invention, L ≦ 0.8 × L _t become as each specific region 20A, it is preferable to set the range of 20B.
Here, regarding the contact line segment between the material to be rolled and the roll when viewed in the cross section of the roll, the length L of the line segment in the specific region for locally supplying the lubricating oil to the surface of the rolling roll is the contact line. if it exceeds 80% of the amount of the total length L _t, meaningless to limit the supply region of the lubricating oil. That is, in this case, the lubricating oil supply amount is reduced, and the effect is substantially the same as when lubricating oil is supplied to the entire contact area between the roll and the material to be rolled. However, there is no merit of securing a friction coefficient in an unlubricated state.

In addition, the length (total length) L of the contact line segment in the specific area where the lubricating oil is supplied in a limited manner depends on the number of locations where seizure or roll wear is likely to occur and the number of locations depending on the rolling shape and dimensions. since may be determined by the length, but not specified in particular lower limit of the length L of the contact line of the specific area, usually the surface portion the entire contact line which contacts the material to be rolled length L _t 20 % Is preferable.

  In the description of the embodiment with reference to FIG. 1, only the upper horizontal roll 13A of the upper and lower horizontal rolls 13A and 13B has been described. It is desirable to set a specific area for the above and set the condition for the contact line segment in the same roll cross section as described above.

Next, an example of a situation in which the lubricating oil supply method of the present invention is applied to hot rolling and implemented will be described with reference to FIGS.
2 and 3 show a lubricating oil supply method according to the present invention as an embodiment applied to hot rolling of an H-section steel using a universal rolling mill.
In the actual hot rolling of the H-section steel, a plurality of rolling passes are repeatedly performed on the material to be rolled (steel) heated to the hot rolling temperature, and finally the H-shaped steel having a predetermined shape and dimensions is obtained. Although it is common to finish shaped steel products, only a certain stage of the process is shown here.

As shown in FIG. 1, the surfaces of the corner portions 15A and 15B of the horizontal rolls 13A and 13B are specified as regions 20A and 20B to which lubricating oil is to be locally supplied as locations where seizure and abrasion of the rolls are likely to occur in advance. Keep it. Specific area 20A, 20B range, as described above, the contact line with the material to be rolled in a specific area in a cross section along the roll axis length L, the total length L _t of the contact line in the cross-section It is determined to be 80% or less.

  As shown in FIGS. 2 and 3, the gas-liquid two-fluid nozzle 22 for atomizing the lubricating oil is arranged so that the lubricating oil is supplied only to these specific regions 20A and 20B. That is, the position and direction of the nozzle, the spread angle of the jet fluid from the nozzle, the distance between the roll surface and the nozzle, and the like are set. In general, in hot rolling, it is usual to supply cooling water to the roll surface for roll cooling.However, the roll cooling water prevents the lubricating oil from adhering to the roll surface or disturbs the supply position. In order to prevent this, a drain plate (not shown) is desirably provided between the cooling water supply position and the lubricating oil atomizing nozzle.

  As the rolls for rolling, especially the horizontal rolls 13A and 13B having the above-mentioned specific region to which the lubricating oil is to be locally supplied, the maximum height roughness Rz of the portion in contact with the material to be rolled is in the range of 0.5 to 50 μm. Use the ones inside. That is, a roll whose maximum height roughness Rz is known to be in the range of 0.5 to 50 μm is selected and used, or the maximum height roughness Rz is previously set to 0.5 to 50 μm by polishing or the like. Use a roll adjusted within the range of.

  After such setting, hot rolling of the H-section steel is performed. In starting the hot rolling, the supply of the lubricating oil is started before the material to be rolled is bitten by the roll. As the lubricating oil, a lubricating oil (raw liquid) having a kinematic viscosity at 40 ° C. within a range of 100 cSt to 800 cSt is preferably supplied to the specific area in a state of being atomized by being ejected from a nozzle together with a nonflammable gas. I do. Further, the flow rate of the non-combustible gas injected from the nozzle at this time is preferably 0.1 m or more and 50 m or less per second.

Further, the lubricating oil supply amount Q per unit area of the roll surface in the specific region is in the range of 0.05 to 20 cc / m ² , and the lubricating oil supply amount Q per unit area of the roll surface is equal to the maximum amount. The lubricating oil injection amount from the nozzle is adjusted so that the relationship with the height roughness Rz satisfies the expression (3), preferably the expression (3 ′). In this embodiment, lubrication is not performed on the vertical rolls 12A and 12B.

  If hot rolling of the H-section steel is performed under such conditions, the specific regions 20A and 20B corresponding to the corners of the surfaces of the horizontal rolls 13A and 13B are sufficiently lubricated, and seizure at that location is prevented. Roll wear can be reliably suppressed, and at the same time, lubricating oil is prevented from spreading to places other than the specified area. It is possible to reliably prevent slip during time and rolling.

  In the above embodiment, the rolling of the H-section steel has been described as an example, but the lubricating oil supply method of the present invention is not limited to the rolling of the H-section steel. That is, locally supplying the lubricating oil to a part of the area means supplying the lubricating oil only to an area of the roll surface that is in contact with the material to be rolled, where seizure or roll wear is likely to occur. Applicable to steel and bar steel. A specific example of the region where the seizure or roll wear is likely to occur is a region where the roll surface comes into contact with a curved portion such as a corner portion of a material to be rolled. The surface portion of the material to be rolled corresponding to the region is indicated by reference numeral 30 in each figure. In the case of hot rolling of a sheet, a roll surface in contact with both edges of the sheet, where a metal flow occurs in the width direction of the sheet as a material to be rolled, corresponds to this region.

  In order to verify the operation and effect of the present invention, as shown in the following Examples 1 and 3, it was investigated whether or not the conditions specified in the present invention were appropriate in the hot rolling of a general plate-shaped steel sheet. A model experiment was performed, and as shown in Example 2, a lubrication rolling experiment was performed in hot rolling of an H-section steel.

[Example 1]
Using a double rolling mill, a hot lubrication rolling experiment as shown in FIGS. 4 and 5 was performed. As the rolling rolls 40A and 40B, rolls made of SKD51 material and having a diameter of 270 mm and a body length of 250 mm were used. The surface roughness of the rolling rolls 40A and 40B was finished by polishing to a predetermined roughness with abrasive paper before rolling. As the material to be rolled 10, a SUS304 material having a width of 220 mm, a thickness of 5 mm, and a length of 350 mm was used. The position of the gas-liquid two-fluid nozzle 20 was adjusted so that the lubricating oil could be supplied by a predetermined length in the axial direction of the upper and lower rolls 40A and 40B by the air atomizing lubrication supply method. Lubricating oil can be supplied from the lubricating oil tank to the nozzle by a fixed-rate delivery pump, and a fixed amount of lubricating oil can be delivered to the nozzle by the flow rate adjusting function of the pump device. A two-fluid spray nozzle was used as the nozzle 20, and the lubricant was atomized by the nozzle and supplied to the roll. The air was adjusted at a source pressure by a pressure regulator and supplied at a predetermined flow rate by a flow meter in the middle of the pipe. Based on the value of the flow meter, the inside diameter of the pipe, and the area of the air discharge port at the tip of the nozzle, the air flow rate was sprayed from the nozzle. The spray width L0 (see the left side of FIG. 5) of the lubricating oil on the roll surface was set to 40 mm. The supply amount of the lubricating oil is determined in consideration of the rotation speed of the roll and the injection width of the lubricating oil so that the same lubricating oil supply amount, that is, the lubricating oil injection amount per unit surface area of the roll (cc / m ² ) is used. It was set by changing the supply amount of the pump by the flow rate adjustment function. As the lubricating oil, a commercially available hot-rolled lubricating oil having a kinematic viscosity at 40 ° C. of 130 cSt (130 mm ² / s) used in the rolling of section steel was used. The air flow rate at the nozzle tip was 15 m / sec.

  In the experiment, the steel material was put in a heating furnace at 900 ° C for 20 minutes or more and heated, and when it became possible to take out the steel material at any time, the upper and lower rolls set at a predetermined roll gap were rotated, and the lubricating oil was turned around one roll. The lubricating oil supply part 42 having a width (L0) of 40 mm was formed by spraying and supplying the same to the roll surface. Thereafter, the steel material heated to 900 ° C. is taken out of the heating furnace, and is rolled by being bitten into a rolling mill. At this time, the rolling was performed such that the place where the lubricating oil was supplied was substantially near the center of the steel material. Lubrication rolling was performed at a rolling reduction of 20% and a rolling speed (roll peripheral speed) of 10 m / min.

  The portion of the rolled material in contact with the roll, on which the lubricating oil has adhered, is attached to the black carbide 44, which has been burned and transferred by the lubricating oil. The measurement was taken as the lubricating oil transfer length L1 (mm) on the material side (see the right side of FIG. 5). Whether or not the lubricating oil could be supplied only to the intended place is determined by the value of L1 / L0 using the lubricating oil injection width L0 supplied to the roll and the lubricating oil transfer length L1 on the material side after rolling. Was calculated as the adhesion ratio α, and the adhesion ratio α = L1 / L0 was evaluated as an index. Thus, when the adhesion ratio α defined by L1 / L0 is 1, the supply width of the lubricating oil supplied to the roll is equal to the width of the lubricating oil transferred to the material. However, in practice, a slight variation occurs in the width of lubricating oil adhesion at the end of the lubricating oil injection part. Therefore, it is assumed that lubricating oil could be supplied only to the intended area up to 1.2. May be. FIG. 6 shows the result of examining the adhesion ratio by changing the conditions of the roll roughness (Rz) and the lubricating oil supply amount (Q) in this experimental method.

When lubricating rolling is performed using a roll having a roll roughness of 0.5 μmRz, the adhesion ratio α is substantially 1 until the lubricating oil supply amount Q is 0.5 cc / m ² , but if it exceeds that, the adhesion ratio α The ratio α became large, and the width of the lubricating oil transferred to the material became wider than the lubricating oil supply width supplied to the roll. Similarly, an experiment was conducted by changing the roll roughness. As a result, if the condition of Q / Rz ≦ 1.2 was satisfied, the lubricating oil could be supplied only to the intended portion where the adhesion ratio α was almost 1, but Q / Rz> 1. .2, it was found that the lubricating oil width L1 transferred to the material was larger than the lubricating oil supply width L0 attached to the roll, and the lubricating oil spread over a wider range than the intended portion.

[Example 2]
In order to prevent seizure occurring at the corners of the horizontal roll of the universal rolling mill during the H-section steel rolling process, an air atomizing lubricating oil supply experimental device was installed, and a lubricating rolling experiment was performed. If lubricating oil is supplied to the entire contact surface of the horizontal roll of the universal rolling mill with the steel material, bite slip occurs and stable lubrication rolling cannot be performed, so only at the corners of the horizontal roll where seizure is likely to occur It is necessary to supply lubricating oil. In order to supply the lubricating oil only to the corner of the horizontal roll, a gas-liquid two-fluid spray nozzle was installed at the corner so that the lubricating oil could be sprayed toward the roll from a direction at 45 degrees to the roll rotation axis. . To prevent the roll cooling water from splashing on the lubricating oil injection site, install a felt drainage plate on the roll cooling water side and install a nozzle for lubricating oil spray below it, and the roll cooling water It did not touch the injection site. The material of the horizontal roll is made of high chrome cast iron, has a diameter of 1250 mm, a body length of 150 mm, and has a radius of 10 mm at the corner. The experiment was performed by changing the axial roughness of the roll before assembling by several levels.

  A fixed-rate delivery pump was used to supply the lubricating oil. One pump device was connected to one nozzle, and lubricating oil was supplied to a total of four locations on the WS and DS sides of the upper and lower horizontal rolls. When pumping lubricating oil from the tank toward the nozzle with a pump device, install a three-way valve between the pump and the nozzle. When lubricating oil is not sprayed and supplied from the nozzle to the roll, lubricating oil is supplied from the three-way valve to the tank. When the lubricating oil was spray-supplied from the nozzle, the three-way valve was switched so that the lubricating oil could be spray-supplied to the roll. The injection timing of the lubricating oil was such that the spray supply of the lubricating oil was started one second before the steel material bites into the rolling mill, and the spray supply of the lubricating oil was stopped one second after the steel material came off the rolling mill. . The lubricating oil used was a commercial hot-rolled lubricating oil for section rolling used in other mills in this process. The kinematic viscosity at 40 ° C. of this lubricating oil is 145 cSt. Air was supplied from an air compressor, and after branching into four, a decompressor was inserted so that the pressure could be adjusted individually for each nozzle. This time, an experiment was performed at an air pressure of 0.4 MPa with reference to the knowledge obtained in Example 1. At this time, the flow velocity from the nozzle is about 15 to 20 m per second. The nozzle was set so that the lubricating oil was supplied in a width of about 110 mm from the center of the corner R of the horizontal roll in a body length direction of 75 mm and a side direction of about 35 mm each. The area where the lubricating oil is supplied is about 70% of the area where the roll comes into contact with the material. The experiment was conducted by changing the lubricating oil supply amount by several levels according to the roll roughness.

  The rolled steel material is an H-section steel product having a flange height of 150 mm, a web height of 150 mm, a flange thickness of 10 mm, and a web thickness of 8 mm. In this rolling mill, one-pass rolling was performed with a flange thickness of about 10% and a web thickness of about 13%. The rolling speed was about 200 m / min, and the steel material temperature was about 900 ° C.

Under the respective lubricating oil supply conditions, the occurrence of seizure at the corner R of the horizontal roll after rolling about 100 rolled materials was compared with when lubricating oil was not supplied.
When rolling was performed without supplying lubrication, a clear streak-like burn mark was generated at the corner R of the horizontal roll at the stage of rolling about 10 rolls. In addition, while attempting to roll while supplying the emulsion to the entire roll using 15% by volume of emulsion lubrication, biting slip occurred and rolling was not possible.

  In the lubrication rolling experiment by the air atomization lubrication supply method, the lubrication rolling was performed by changing the roll roughness and the lubricating oil supply amount, and if there was no occurrence of biting slip or rolling slip, about 100 steel materials were used. Observation of the occurrence of seizure was conducted by observing the corner R of the horizontal roll after rolling.

As a result, as shown in Table 1, it became clear that the use of the present invention can suppress the seizure of the corner R without causing biting slip or rolling slip. Under the conditions that caused the bite slip, the bite slip occurred from the start of rolling until the ten steel materials were rolled, and thus the rolling was interrupted. Therefore, the evaluation of seizure was not performed.
According to the second embodiment, even in the rolling in which the lubricating oil cannot be supplied to the entire contact area, the rolling is performed while supplying the lubricating oil only to the portion where the lubricating oil needs to be supplied. It has been clarified that rolling can be performed without any troubles such as troubles, and the effect of lubricating rolling can be enjoyed.

[Example 3]
According to the same experimental method as in the first embodiment, the lubricating oil supply length to the roll with respect to the plate width of the material to be rolled (corresponding to the total length Lt of the contact line in the third embodiment) (the third embodiment described above) The ratio (corresponding to the length L of the line segment in the specific region for supplying the lubricating oil) (the ratio indicated by “β” in Table 2) was changed from 20% to 100% to investigate whether or not slippage occurred. did. The supply amount of the lubricating oil was 1 cc / m ^2, and the roughness of the roll was 0.9 μmRz. The experiment was performed under the same other rolling conditions as those in Example 1.

  As a result, as shown in Table 2, slip occurs when the lubricating oil supply length of the roll exceeds 80% of the sheet width of the material to be rolled, and when 80% or less, the slip does not occur and the slip is stable. It has been found that lubricating rolling is possible.

  Although the preferred embodiments and examples of the present invention have been described above, these embodiments and examples are merely examples within the scope of the present invention, and do not depart from the scope of the present invention. Thus, addition, omission, substitution, and other changes of the configuration are possible. That is, the present invention is not limited by the above description, but is limited only by the appended claims, and can be appropriately modified within the scope.

10 Rolled material 13A, 13B Horizontal roll 20A, 20B Specific area 22 Gas-liquid two-fluid nozzle

Claims (3)

In a state where the lubricating oil is atomized by the non-flammable gas using the gas-liquid two-fluid nozzle, the lubricating oil is locally supplied to a part of a portion of the rolling roll surface that comes into contact with the material to be rolled. In the lubricating oil supply method in hot rolling,
A roll having a maximum height roughness Rz of a portion in contact with the material to be rolled having a maximum height roughness Rz in the range of 0.5 to 50 μm is used. Within the range of 0.5 to 20 cc / m ² ,
The lubricating oil supply amount Q per surface area of the rolling roll is adjusted according to the maximum height roughness Rz such that the ratio Q / Rz between the lubricating oil supply amount Q and the maximum height roughness Rz is 1.2 or less. Set and lubricate ,
Hot rolling , wherein the length of the region in the direction along the rolling roll axis direction is 80% or less of the length along the rolling roll axis direction of the entire surface portion in contact with the material to be rolled. Lubricating oil supply method. The lubricating oil supply method in hot rolling according to claim 1,
The lubricating oil supply amount Q per surface area of the rolling roll is changed according to the maximum height roughness Rz such that the ratio Q / Rz between the lubricating oil supply amount Q and the maximum height roughness Rz is 1.0 or less. A lubricating oil supply method in hot rolling, characterized by setting and lubricating. The lubricating oil supply method in hot rolling according to claim 1 or 2 ,
A lubricating oil supply method in hot rolling, wherein a lubricating oil having a kinematic viscosity at 40 ° C within a range of 100 to 800 cSt is used.

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