JP5104389B2 - Cold rolling roll cooling method, steel sheet cold rolling method, and cold rolling roll cooling device - Google Patents

Description

The present invention relates to a cooling method for a cold rolling roll, a cold rolling method for a steel plate, and a cooling device for a cold rolling roll when the steel plate is cold-rolled by a cold tandem rolling mill of a circulating oil supply system.

When cold rolling a steel plate, as a lubricant for reducing the friction generated between the steel plate and the roll during rolling, and a work roll (hereinafter referred to as “heat roll”) heated by frictional heat and processing heat generated during rolling. Rolling oil is used as a coolant for simply cooling the roll and the steel sheet.

  Here, in cold rolling, emulsion rolling oil is generally used as rolling oil.

  FIG. 3 schematically shows the concept of rolled emulsion oil. Emulsion rolled oil is obtained by dispersing and diluting (emulsifying) water in which a surfactant is attached to a base oil. In the agent, one end of the long chain molecule is composed of a lipophilic group and the other end is composed of a hydrophilic group.

  Emulsion rolling oil is characterized by concentration and average particle size. The concentration of the emulsion rolling oil is the ratio of the mass of the base oil to the total mass of the emulsion rolling oil. The average particle size is an average value of the diameters of emulsion rolling oil particles (emulsion particle size).

  When mixing the surfactant with the base oil, the average particle size of the emulsion rolling oil can be adjusted by adjusting the number of rotations of the stirrer and the pump and changing the applied shear force.

  Emulsion rolling oil supply method for cold rolling is a direct oil supply method (direct method) that does not collect and reuse emulsion rolling oil that has been supplied to rolls or steel plates, and circulation of emulsion rolling oil. There is a circulating oil supply method (recirculation method) to be used.

  Further, in many cases, the circulating oil supply system means a system in which oil-in-water (O / W) emulsion rolling oil in which the concentration of the emulsion rolling oil is adjusted to 1 to 5% by mass is circulated and used.

  Furthermore, in the circulating oil supply system, in many cases, the roll bite (the steel plate part where the roll is actually rolling the steel plate) of each rolling mill constituting the cold tandem rolling mill is lubricated between the steel plate and the roll. And a means for supplying the rolled emulsion oil for cooling the roll on the outlet side.

  Although the purpose is different between the entry side and the exit side, in the present invention, both the supply means on the entry side intended to lubricate between the steel sheet and the roll and the supply means on the exit side intended to cool the roll are both It is assumed that it is included in a cold rolling roll cooling device.

  In recent years, for the purpose of improving productivity, high-speed rolling of 2000 mpm or more of a thin material (thin material) having a sheet thickness after rolling of 0.3 mm or less, which tends to reduce the rolling weight per unit time, is directed. Yes.

  On the other hand, the conventional circulating oil supply system is insufficiently lubricated, and the occurrence of surface wrinkles on the steel sheet side caused by torsional vibrations of the roll called chattering and its drive system and the roll and steel sheet seizure called heat scratching is an obstacle. It has become.

  Conventionally, several methods for solving the lack of lubrication have been proposed, but those capable of high-speed rolling at the same time are under development.

  The higher the rolling speed, the higher the peripheral speed of the roll, so the amount of emulsion rolling oil supplied per unit time to cool the roll is relatively reduced, and the convex shape caused by the thermal expansion of the roll, called the thermal crown. The protrusion (crown) of the film tends to grow on the surface layer of the roll.

  When the distribution (profile) in the body length direction of the profile of the roll accompanying the growth of the thermal crown changes with time, the shape of the steel sheet after rolling tends to be disturbed.

  Typical methods for controlling the shape of the steel sheet after rolling are roll bending and roll shift. However, the shape control capability of these shape control actuators is limited, and the thermal crown is completely removed. Compensation is not easy, and as a trend in recent years, when thin rolling and high-speed rolling are aimed, the problem of unsatisfactory productivity improvement due to defective shape of the steel sheet after rolling has been faced.

In this regard, the following methods have been proposed in the past for the purpose of suppressing the growth of the thermal crown generated on the roll.
(1) A method of controlling the flow rate of the emulsion rolling oil for cooling the roll so as to have a distribution in the body length direction of the roll so as to match the target roll profile by the model formula (Patent Document 1),
(2) Roll cooling method by jacket cooling (Patent Documents 2 and 3),
(3) A method of cooling a part of the emulsion rolling oil to be circulated and supplying it to the roll (Patent Document 4)
In addition, in order to quote patent document 5 in the [means for solving a problem] mentioned later, it mentions together here.
Japanese Patent No. 39588992 Japanese Patent Laid-Open No. 11-277113 Japanese Patent Laid-Open No. 11-277115 Japanese Patent Publication No. 07-016691 JP 2005-305473 A

In any of Patent Documents 1 to 3, water is used as a medium in the emulsion rolling oil supplied to the roll.

  By the way, since the emulsion rolling oil is usually heated even in the circulating oil supply system, the water in the emulsion rolling oil evaporates little by little.

  In addition to the rolling mill oil, water is also supplied to the roll for the purpose of cooling.

  Conventionally, the amount of other water after cooling the roll that flows into the system that circulates and uses the emulsion rolling oil was about the same as the amount of water that evaporates. It was suppressed to such an extent that it would not be a problem in practice.

  However, in recent years, the number of target materials for high-speed rolling as described above has increased as a ratio, and the cooling capacity of the roll has started to be required, as well as the amount of emulsion rolling oil required per unit time, and the emulsion described above. A large amount of other water flowing into the system that circulates and uses the rolling oil has been required.

  For this reason, the amount of other water that flows into the system that circulates and uses the emulsion rolling oil is somewhat larger than the amount of water that evaporates, and the decrease in the concentration of the circulating rolling emulsion oil cannot be ignored. The possibility has come out.

  When cold rolling is performed using such emulsion rolling oil, lubrication is insufficient due to a decrease in the concentration of the emulsion rolling oil that is circulated and used, and the above-described chattering and heat scratch may occur.

  In Patent Document 4, since a part of the emulsion rolling oil used in circulation is cooled and used for cooling the roll, the concentration fluctuation of the emulsion rolling oil used in circulation can be suppressed. In addition to the concentration, there are other factors that affect the properties of the emulsion rolling oil, such as iron powder and ESI (emulsification dispersibility index), especially iron powder produced by cold rolling of steel sheets. A new problem has arisen that scum (metal soap in which iron powder is combined with fats and oils) due to flocculation coagulates and solidifies and blocks the pipes and nozzles.

  Of the cold tandem rolling mills, especially the final rolling mills, in many cases, dull rolling is performed for the purpose of securing plate-passability after the next process. Compared with general bright rolling, rolls and steel plates are used. There is a tendency that the amount of iron powder produced is large. In addition, the amount of iron powder generated may increase abruptly when, for example, rolling steel sheets having greatly different deformation resistance are continuously rolled, including rolling mills other than the final rolling mill that constitutes the cold tandem rolling mill.

  The present invention has been made to solve such problems as in the prior art, and stabilizes the properties of emulsion rolling oil that is circulated when cold rolling a steel sheet with a cold tandem rolling mill of a circulating oil supply system. By suppressing the roll profile distribution (profile) of the roll profile over time with the growth of the thermal crown, the steel plate after rolling is prevented from being disturbed and the scum is coagulated and solidified. The purpose is to prevent the blockage of piping and nozzles.

That is, the present invention is as follows.
[ 1 ] The first emulsion rolling oil to be circulated is supplied to the rolls of each rolling mill constituting the cold tandem rolling mill, the pour point of the emulsion rolling oil is set to 5 ° C. or lower, and at least one From the outlet side of the roll to the roll, the second emulsion rolling oil branched and used from the supply pipe for the first emulsion rolling oil is used, and the iron powder concentration is 1000 ppm through the iron powder concentration control means and the cooling means. The method for cooling a cold rolling roll, characterized in that the temperature is adjusted to 30 to 60 ° C. and then supplied.
[ 2 ] A method for cold rolling a steel sheet using the method for cooling a cold rolling roll according to [1].
[ 3 ] A circulating oil supply system of emulsion rolling oil for the rolls of each rolling mill constituting the cold tandem rolling mill is provided. The circulating oil supply system includes a first emulsion rolling oil supply system and the first emulsion rolling. A second emulsion rolling oil supply system for supplying a second emulsion rolling oil branched from an oil supply system and circulated to at least one roll from the outlet side of the roll, and the emulsion rolling oil And a cooling means that can adjust the emulsion rolling oil temperature to 30 to 60 ° C. in the second emulsion rolling oil supply system, and the emulsion rolling oil iron powder concentration to 1000 ppm or less A cooling device for a cold rolling roll, characterized in that an iron powder concentration control means capable of adjustment is installed.

According to the present invention, when the steel sheet is cold-rolled by a cold tandem rolling mill of a circulating oil supply type, the profile of the roll is increased along with the growth of the thermal crown by stabilizing the properties of the emulsion rolling oil used in circulation. It is possible to prevent the distribution (profile) in the barrel length direction from changing with time, to prevent the shape of the steel sheet after rolling from being disturbed, and to prevent the piping and nozzles from being blocked due to the coagulation and solidification of the scum.

The inventors have wondered whether there is a method that can stabilize the properties of the emulsion rolling oil that is circulated and can effectively suppress the thermal crown of the roll. As a result, the following conclusions were reached.

  First of all, for the cooling of the rolls, pipes and nozzles by solidifying the base oil are used by using a base oil having a low pour point of 5 ° C. or less while using the emulsion rolling oil that is circulated and used. Prevent blockage. The pour point is a temperature obtained by adding 2.5 ° C. to a temperature at which the oil is completely solidified.

  And it is also preferable to supply the 2nd emulsion rolling oil, after reducing temperature through a cooling means.

  Since the rolling emulsion oil used in circulation reaches an enormous amount as a whole, it is preferable that the control for lowering the temperature via the cooling means is limited to the emulsion rolling oil necessary for cooling the roll.

  In this sense, the second emulsion rolling oil is branched from the pipe of the first emulsion rolling oil that is circulated and supplied, and the second emulsion rolling oil is supplied via the cooling means. Is preferred.

  Alternatively, it is also preferable to control the iron powder concentration in the circulating rolled emulsion oil.

  As a method of controlling the iron powder concentration, there is a method of changing the set load of the magnet filter, as in Patent Document 5.

  Since the emulsion rolling oil used in circulation reaches an enormous amount as a whole, it is preferable to control the iron powder concentration only to the emulsion rolling oil necessary for cooling the roll.

  Also from this meaning, the second emulsion rolling oil is branched from the piping of the first emulsion rolling oil to be circulated and supplied, and the second emulsion rolling oil is supplied via the iron powder concentration control means. It is preferable to do so.

  In the present invention, the growth of the thermal crown of the roll is suppressed by one or more of these.

  Emulsion rolling oil used for roll cooling uses a base oil with a pour point as low as 5 ° C. or lower, or by controlling the concentration of iron powder to an appropriate level to suppress the amount of scum generated, In addition to preventing clogging, the properties of the emulsion rolling oil are stabilized, allowing use over a longer period of time.

  Hereinafter, an example of an embodiment of the present invention will be described. FIG. 1 is a view showing an example of a circulating tandem cold tandem rolling mill suitable for applying the present invention.

  In addition, FIG. 1 has shown the cold tandem rolling mill 100 which has a 1st rolling mill thru | or a 5th rolling mill in order from the conveyance direction entrance side of the steel plate 1 shown by the arrow.

  In this cold tandem rolling mill 100, tension rolls and deflores (not shown) are installed between adjacent rolling mills.

  In FIG. 1, on the entry side of each rolling mill, there is a coolant coolant header 3 for lubricating between the steel sheet of the roll tool and the roll, and on the exit side, there is a coolant coolant header 4 for cooling the roll. is set up.

  The first emulsion rolling oil 19 is supplied to the roll 2 through means for supplying the emulsion rolling oil such as the lubricating coolant header 3 and the cooling coolant header 4 (lubrication). The coolant header 3 for cooling and the coolant header 4 for cooling both supply the first emulsion rolling oil).

  The emulsion rolling oil is stored in the tank 5 and is pumped by a pump 6 provided in the middle of a supply pipe 7 for supplying the emulsion rolling oil to be circulated and installed in each rolling mill through the supply pipe 7. Further, it is supplied to the roll 2 through a means for supplying emulsion rolling oil, such as the lubricating coolant header 3 or the cooling coolant header 4 (the tank for the means for supplying the first emulsion rolling oil described above). 5, the pump 6 and the supply pipe 7 are added to the first emulsion rolling oil supply system.)

  The supply of the emulsion rolling oil to the roll 2 is preferably performed from the start of rolling.

  In tank 5, warm water (dilution water) and base oil are mixed, adjusting the rotation speed of stirrer 10, and the average particle diameter of emulsion rolling oil is adjusted.

  Here, the pour point of the base oil used for the emulsion rolling oil is 5 ° C. or less. When the temperature exceeds 5 ° C., the emulsion rolling oil is solidified inside the pipe 12 and inside the nozzle header 17 (described later) due to cooling of the emulsion rolling oil in the cooling device 14 (described later), and the piping 12 may be blocked. Because there is.

  The lower limit of the pour point of the base oil is not particularly specified, but it is −40 ° C. or higher in view of the reality of the whole kind of oil used for cold rolling.

  As the base oil of the rolled emulsion oil, it is preferable to use a mixture of one or more of natural fats and oils, fatty acid esters, and hydrocarbon-based synthetic lubricating oils, and the composition is such that the pour point is 5 ° C. or lower. Alternatively, it is preferable to adjust the mixing ratio.

  For example, when using natural fats and oils as the base oil, vegetable oils such as mineral oil and palm oil, and animal oils such as beef tallow can be used.

  Further, for example, when a fatty acid ester is used as the base oil, a diester that is an ester of a monohydric alcohol and a divalent fatty acid, a polyhydric alcohol such as neopentyl glycol, trimethylolpropane, pentaerythritol, and a monohydric fatty acid A polyol ester by a combination of the above can be used.

  Further, as the base oil, for example, when a hydrocarbon-based synthetic lubricating oil is used, poly-α-olefin that can obtain various viscosities can be used. Furthermore, additives often used in cold rolling oils such as oiliness improvers, extreme pressure additives, and antioxidants may be added to these rolling oils.

  Further, as the surfactant added to the emulsion rolling oil, either ionic or nonionic surfactants may be used, and those often used in the circulating oil supply system may be used.

  Here, as the emulsion rolling oil, the base oil is preferably diluted with water to a concentration of 1 to 5% by mass, more preferably 1.2 to 3.0% by mass, and a surfactant is added. It is preferable to use an oil-in-water (O / W) emulsion in which oil is dispersed in water.

  In addition, the average particle diameter of the emulsion rolling oil is preferably 15 μm or less, more preferably 7 to 10 μm.

  The emulsion rolling oil pumped from the tank 5 through the supply pipe 7 by the pump 6 is supplied from the coolant coolant header 3 installed on the entry side of each rolling mill and the coolant coolant header 4 installed on the exit side, respectively. , Roll bite and roll 2 are supplied.

  Of the supplied emulsion rolling oil, those that are taken out by the steel plate 1 or lost by evaporation are recovered by the oil pan 8 and returned to the tank 5 via the return pipe 9.

  The supplied emulsion rolling oil is recovered and reused (circulated) by the tank 5, the pump 6, the supply pipe 7, the lubricating coolant header 3, the cooling coolant header 4, the oil pan 8, and the return pipe 9. A circulation system is formed.

  Moreover, in this Embodiment, as shown in FIG. 1, the means to supply the 2nd emulsion rolling oil 20 is provided in the exit side of the final rolling mill of the cold tandem rolling mill 100, and moderate temperature is provided. Or, more preferably, the second emulsion rolling oil 20 adjusted to an appropriate iron powder concentration is supplied to the roll 2.

  In addition, in FIG. 1, although the case where the means to supply the 2nd emulsion rolling oil 20 is installed only in the exit side of the final rolling mill is shown, this invention is not limited to this, 1st rolling By providing one or two or more rolling mills on the outlet side of the rolling mill to the fifth rolling mill (in the example of FIG. 1, the fifth rolling mill is a final rolling mill, but not limited to this), The object of the present invention can be achieved.

  For example, as the material becomes thinner and as it goes to the latter rolling mill, the rolling speed becomes higher and the cooling time becomes shorter. Therefore, it is preferable to install means for supplying the second emulsion rolling oil 20 to the latter rolling mill.

  Here, the definition of the latter-stage rolling mill may differ depending on each company or each factory, but in this embodiment, it goes back from the final rolling mill and is at most half of all rolling mills or divisible by half. If not, define it as just an intermediate rolling mill. “Maximum” means that it does not go so far. For example, in the example of FIG. 1, there may be only the final rolling mill and the preceding rolling mill.

  Hereinafter, the means for supplying the second emulsion rolling oil 20 will be described in detail.

  In the example of the embodiment shown in FIG. 1, the means for supplying the second emulsion rolling oil 20 supplies the roll 2 with the second emulsion rolling oil 20 installed on the outlet side of the rolling mill. A nozzle header 17 for performing, a pipe 12 for supplying the second emulsion rolling oil 20 toward the nozzle header 17, a flow control valve 15 for controlling the flow rate of the second emulsion rolling oil 20, and preferably Comprises cooling means 14 or more preferably iron powder concentration control means 13 (the same applies to the second emulsion rolling oil supply system).

  The first emulsion rolling oil supply system and the second emulsion rolling oil supply system together constitute the emulsion rolling oil circulation oil supply system of the present invention.

  The emulsion rolling oil installed on the entrance side of the rolling mill for lubricating the roll bite between the steel plate and the roll may also be controlled in temperature, or more preferably in iron powder concentration, in which case Included in the means for supplying the second emulsion rolling oil 20.

  Here, the nozzle header 17 is provided with a spray nozzle for supplying the second emulsion rolling oil 20 to the roll 2.

  In the example shown in FIG. 1, the nozzle header 17 is installed above and below both the upper and lower rolls 2, and the supplied second emulsion rolling oil 20 is conveyed by a steel plate indicated by an arrow. It is comprised so that it can supply by injecting toward the exit side of a rolling mill, ie, the back outer peripheral surface of the roll 2, seeing a direction.

  The supplied second emulsion rolling oil 20 comes into contact with the rear outer peripheral surface of the roll 2 to form a water film flow, and removes heat from the roll 2.

  The pipe 12 branches from the supply pipe 7, and the second emulsion rolling oil 20 supplied to the pipe 12 is supplied with the cooling device 14 (cooling means), or more preferably with the iron powder concentration control device 13 (iron powder). Via the concentration control means), the temperature or more preferably the iron powder concentration is controlled and supplied.

  If it is not necessary to adjust the profile (profile) of the profile of the roll 2 accompanying the growth of the thermal crown, the temperature of the second emulsion rolling oil 20 or the control of the iron powder concentration is stopped. May be.

  In the cooling device 14, the temperature of the second emulsion rolling oil 20 is adjusted. As the cooling device 14, the higher the heat exchange efficiency, the better. However, the cooling device 14 may exchange heat with a liquid cooling medium, or may exchange heat with a gaseous cooling medium.

  Here, the temperature of the second emulsion rolling oil 20 is preferably as low as possible. However, since the viscosity of the rolling oil increases as it approaches the pour point, it may solidify and the cooling device 14 and the pipe 12 may be blocked. Therefore, the temperature of the emulsion rolling oil at the time of supply is preferably 30 ° C. or more and 60 ° C. or less.

  It is also preferable that the lower limit temperature at which the solidification does not occur is converted to the temperature of the second emulsion rolling oil 20 in the cooling device 14 to obtain the number of times by an experiment or the like in advance and adjusted to the temperature or higher.

  In the iron powder concentration control device 13, the iron powder concentration of the second emulsion rolling oil 20 is adjusted. The iron powder concentration of the second emulsion rolling oil 20 is preferably controlled to 1000 ppm or less, more preferably 500 ppm or less.

  As the iron powder concentration control device 13, it is preferable to use a magnetic filter such as an electromagnetic filter or a magnet separator to adsorb and remove the iron powder. However, the present invention is not limited to this, and a method such as centrifugation is used. May be.

  The supply flow rates of the first emulsion rolling oil 19 and the second emulsion rolling oil 20 are preferably adjusted according to the conveyance speed when rolling the steel sheet, the dimensions of the steel sheet, and the like. Information relating to the attributes of the steel sheet, such as the conveyance speed when rolling the steel sheet and the dimensions of the steel sheet, is input to the process computer 16 and the flow rate of the emulsion rolling oil is determined by calculation within the process computer 16 and determined. The flow rate of the emulsion rolling oil is commanded to the pump 6 and the flow rate control valve 15 via a control device (not shown), and the flow rate control valve 15 is controlled so as to have the actually determined flow rate of the second emulsion rolling oil 20. Is done.

  Here, when the supply flow rate of the second emulsion rolling oil 20 exceeds 20000 L / m 2 / min in terms of flow density (volume of the emulsion rolling oil supplied per unit area per unit area), the roll is turned on. Since the effect of cooling is saturated, it is preferable to set it to 20000 L / m2 / min or less. On the other hand, if it is less than 1000 L / m 2 / min, a sufficient cooling effect cannot be obtained.

  The supply flow rate of the first emulsion rolling oil 19 is not for cooling the roll but for lubrication between the roll and the steel plate, and the upper and lower limits thereof are the case of the supply flow rate of the second emulsion rolling oil 20. The same.

  In order to prevent the second emulsion rolling oil 20 supplied from coming into contact with the rear outer peripheral surface of the roll 2 to form a water film flow and then falling onto the steel plate 1, draining is performed below the upper roll 2. It is also preferable that a seal 18 is provided so that the second emulsion rolling oil 20 is discharged from the side. On the other hand, the second emulsion rolling oil 20 supplied to the lower roll 2 naturally falls by gravity and is discharged downward without installing the draining seal 18.

  Or when the fall of the 2nd emulsion rolling oil 20 on the steel plate 1 cannot fully be prevented, the air purge apparatus which is not illustrated is installed in the exit side of the said rolling mill, and the water draining on the steel plate 1 is performed. Also good.

  In the example of FIG. 1, the emulsion rolling oil supplied to the roll 2 from the means for supplying the second emulsion rolling oil 20 is collected in the oil pan 8, collected together with the first emulsion rolling oil 19, and returned to the return pipe 9. Is returned to the tank 5 via.

( Reference Example 1) Using a cold tandem rolling mill 100 composed of the first to fifth rolling mills shown in FIG. 1, a sheet thickness of 2.3 mm and a sheet width of 850 to 850 before rolling with the first rolling mill is started. A 950 mm tin plate (steel plate 1) was rolled by 100 tons at a target speed of 2100 m / min to a sheet thickness of 0.200 mm after rolling with a fifth rolling mill.

  Emulsion rolled oil is a base oil to which animal and vegetable fats and oils are added based on synthetic esters (mass% 70 synthetic esters vs. animal and vegetable fats and oils 25) is 3.0% by mass with respect to the whole emulsion rolled oil. It was assumed that 1% by mass of each of the oily agent and the antioxidant was added to the whole rolling oil, and 3% by mass of the nonionic surfactant was added as the surfactant.

  The pour point of the emulsion rolling oil was 2.5 ° C. After sufficient stirring by the stirrer 10 in the tank 5, an emulsion rolling oil having an average particle size of 9 μm and a temperature of 60 ° C. was obtained. In addition, the iron powder density | concentration in the emulsion rolling oil at this time was 500 ppm.

In Reference Example 1, the first emulsion rolling oil 19 pumped through the supply pipe 7 from the tank 5 by the pump 6 is installed on the lubricant coolant header 3 installed on the inlet side of each rolling mill or on the outlet side thereof. The coolant was supplied to the roll bite and roll 2 from the cooling coolant header 4.

  In addition, according to the plate | board width of the steel plate 1 to cold-roll, the length of the roll 2 trunk | drum length direction of the part to which the 1st emulsion rolling oil 20 is supplied toward the roll 2 was adjusted. The flow density was adjusted to 12000 L / m2 / min.

( Reference Example 2) In Reference Example 2, the first emulsion rolling oil 19 pumped from the tank 5 by the pump 6 through the supply pipe 7 is supplied with the lubricating coolant header 3 installed on the inlet side of each rolling mill. The second emulsion rolling oil 20 supplied from the coolant header 4 for cooling to the roll bite and the roll 2 from the cooling side 4 installed on the outlet side and similarly pumped through the pipe 12 from the tank 5 by the pump 6 is the final. It was made to supply toward the roll 2 from the nozzle header 17 installed in the exit side of the 5th rolling mill which is a rolling mill. The temperature of the 2nd emulsion rolling oil 20 at the time of supplying toward the roll 2 was controlled at 35 degreeC. The rest was the same as in Reference Example 1 above.

(Example 3) While controlling the temperature of the 2nd emulsion rolling oil 20 at the time of being supplied toward the roll 2 to 35 degreeC, the iron powder density | concentration is controlled to 300 thru | or 350 ppm, and other than those, said reference example 1 Was the same.

  (Comparative example) As a comparative example, the ratio of the synthetic ester in the base oil used in the rolled emulsion oil was changed (by mass%, the synthetic ester 55 vs. animal and vegetable oil 45), and the pour point was 7.5 ° C. The emulsion rolling oil having the same flow density and the same temperature as the above example was supplied from the nozzle header 17 using oil, but the base oil was solidified in the pipe 12 and the nozzle header 17 of the second emulsion rolling oil 20. Since the blockage due to was confirmed, the supply of the emulsion rolling oil was stopped.

About the above reference examples, examples, and comparative examples, the profile (profile) in the body length direction of the contour of the roll 2 of the final rolling mill obtained by extracting the steel plate 1 of 100 tons after rolling was examined. The result is shown in FIG. FIG. 2 shows the height of the thermal crown per diameter of the cross section of the roll 2 as viewed from the body length end of the roll 2.

In contrast to the thermal crown formed like a drum like the comparative example, in Reference Example 1, the height of the thermal crown was reduced by adjusting the pour point of the circulating rolled emulsion oil to 5 ° C. or less. .

In Reference Example 2, the second emulsion rolling oil 20 was cooled by the cooling means 14, and the height of the thermal crown was further reduced by heat removal by the cooled second emulsion rolling oil 20.

  However, when the nozzle header 17 was confirmed, blockage due to scum was observed at several locations of the nozzle.

  On the other hand, in Example 3, the second emulsion rolling oil 20 supplied from the nozzle header 17 is cooled by the cooling means 14, and the iron powder concentration of the second emulsion rolling oil 20 is further changed by the iron powder concentration control means 13. By controlling it, the height of the thermal crown could be reduced most.

Diagram for explaining an example of an embodiment of the present invention Diagram for explaining the effect of the present invention Diagram for explaining emulsion rolling oil

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel plate 2 Roll 3 Lubricant coolant header 4 Coolant coolant header 5 Tank 6 Pump 7 Supply piping 8 Oil pan 9 Return piping 10 Stirrer 12 Piping 13 Iron powder concentration control means 14 Cooling means 15 Flow control valve 16 Process computer 17 Nozzle header 18 Draining seal 19 First emulsion rolling oil 20 Second emulsion rolling oil 100 Cold tandem rolling mill

Claims (3)

The roll of the rolling machine constituting the tandem cold rolling mill, said first emulsion rolling oil to be recycled is supplied, together with the pour point of the emulsion rolling oil to 5 ° C. or less, in at least one of the rolls From the outlet side of the roll, the second emulsion rolling oil branched from the supply pipe for the first emulsion rolling oil and used for circulation is fed with an iron powder concentration of 1000 ppm or less and the temperature through the iron powder concentration control means and the cooling means. A method for cooling a cold rolling roll, which is adjusted to 30 to 60 ° C. and supplied. Steel cold rolling method using a method of cooling cold rolling roll according to claim 1. A rolling oil supply system for emulsion rolling oil to the rolls of each rolling mill constituting the cold tandem rolling mill is provided. The circulating oil supply system includes a first emulsion rolling oil supply system and the first emulsion rolling oil supply. A second emulsion rolling oil supply system for supplying the second emulsion rolling oil to be circulated and branched from the system to at least one roll from the outlet side of the roll, and the pour point of the emulsion rolling oil And the cooling means for adjusting the emulsion rolling oil temperature to 30 to 60 ° C. in the second emulsion rolling oil supply system, and the emulsion rolling oil iron powder concentration can be adjusted to 1000 ppm or less. A cold rolling roll cooling device, characterized in that iron powder concentration control means is installed.

Images