JPH079022A - Rolling oil supply method - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to maintain a stable rolling condition without the need for manual intervention. [Structure] The rolling oil sent from the rolling oil tank 20 by the oil feed pump 24 and the water sent from the water tank 26 by the water feed pump 28 are mixed in a mixer 30 to form an emulsion, which is then fed from a nozzle 34 to a rolling mill ST. When jetting onto the surface of the strip S being rolled by the work roll 32, the drive of the electric motor 22 is controlled by the host computer 38 and the computer 36, and the amount of rolling oil supplied by the rolling oil pump 24 is
The ratio of the oil film thickness at the inlet of the plastic working portion to the work roll surface roughness is controlled to 0.3 or more and 3.5 or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling supply method, and more particularly to a rolling oil supply method effective for supplying rolling oil to a strip when the strip is rolled by a rolling mill.

[0002]

2. Description of the Related Art Generally, when rolling a strip with a rolling mill, rolling oil is applied to the strip in order to improve the rolling property. As a supply method, there is adopted a method in which a coolant in an emulsion state in which water and rolling oil are mixed is jetted from a nozzle to a strip. An example is shown in FIG.
Will be explained.

FIG. 5 shows an example of the case where a transient type rolling oil supply device called a direct system is used in cold rolling, and the rolling oil is supplied as follows.

The rolling oil stored in the rolling oil tank 1 is pressurized by the pump 2 and the flow rate of the rolling oil detected by the flow meter 3 is fed back to supply a predetermined amount of rolling oil to the mixing tank 4. . At the same time,
The water stored in the water tank 5 is boosted by the pump 6, and the flow rate of the water detected by the flow meter 7 is fed back to supply a predetermined amount of water to the mixing tank 4 as well.

In this mixing tank 4, the supplied rolling oil and water are stirred and mixed to form a coolant in an emulsion state, and the coolant is pressurized by a pump 8 to be fed from a nozzle 9 to a rolling mill 10. The strip S that is being rolled by the rolling roll (work roll) 11 is jetted. This rolling oil supply method can be used not only for cold rolling but also for hot rolling.

In the above-described direct type rolling oil supply method, usually, the injection amount of emulsion is changed according to the rolling speed of the strip so that the amount of rolling oil adhered per unit area of the strip becomes constant. Then, the flow rate of the emulsion is controlled.

Japanese Patent Publication No. 63-124 discloses a method for rapidly changing the concentration of rolling oil, in which the rolling oil is supplied to the stands in the tandem cold rolling, and the mixing of the rolling oil and the hot water is performed for each stand. A method is disclosed just before the rolling oil header.

[0008]

However, in the method of controlling the amount of rolling oil adhering to the unit area of the strip before rolling to be constant, the oil flow rate is increased when the surface roughness of the work roll is high, and conversely low. In this case, the oil flow rate must be reduced, and since the oil flow rate needs to be finely adjusted depending on the material of the rolled material, there has been a problem that manual intervention is unavoidable.

When it is necessary to change the rolling speed,
There is a problem that the rolling state becomes unstable during the acceleration / deceleration, and the plate thickness accuracy deteriorates.

The present invention has been made to solve the above-mentioned conventional problems, and provides a rolling oil supply method capable of always maintaining a stable rolling state without requiring manual intervention. The task is to do.

[0011]

SUMMARY OF THE INVENTION The present invention provides a rolling oil supply method in which rolling oil is mixed with water to form an emulsion when the strip is rolled by a rolling mill, and the emulsion is sprayed from a nozzle onto the surface of the strip. The above object is achieved by controlling the amount of rolling oil supplied so that the ratio of the oil film thickness at the inlet of the plastically processed portion to the surface roughness of the work roll is maintained at an appropriate value.

In the rolling oil supply method of the present invention, a coagulant for promoting the separation of water and oil in the emulsion is added to the rolling oil, and the plastic working portion inlet with respect to the surface roughness of the work roll is added. By maintaining the ratio of the thickness of the oil film in the range of 0.3 or more and 3.5 or less, the above-mentioned problem is surely achieved.

[0013]

As a result of various studies on the method of supplying rolling oil to enable stable rolling operation, the present inventors have found that the surface roughness of the work roll and the oil film at the inlet of the plastic working portion (strip biting portion) It was found that there is a close relationship with the thickness. This is because the friction coefficient in the roll bite (friction surface) has a great influence on the rolling state, and this friction coefficient is determined by the oil film thickness at the inlet of the plastic working part and the surface roughness of the work roll. it is conceivable that.

The present invention was made based on the above findings, and the amount of rolling oil supplied is adjusted so that the ratio of the oil film thickness at the inlet of the plastic working portion to the surface roughness of the work roll is maintained at an appropriate value. By controlling, it becomes possible to always maintain a stable rolling state.

The oil film thickness at the plastic working part inlet is
It can be obtained by the simultaneous equations represented by the following equations (1) to (3). However, the initial conditions are h = h ₁ and P =
σ, h = h ₂ and P = 0.

D P / d X = −6 η (V _R + V _S ) · (h −h ₁ ) / h ³ (1) T _m = (T _S + T _R ) / 2 + {η (V _R −V _S ) ² /(12K)}...(2) η = η _o exp {αP−β (T _m −T _o )} (3)

Here, P: pressure, η: viscosity, V _R : roll speed, V _S : strip speed, h: oil film thickness, h ₁ : plastic working part inlet oil film thickness, h ₂ : rolling speed, oil flow rate Calculated coating oil film thickness, T _m : average temperature in oil film, T _R : roll temperature, T _S : strip temperature, K: rolling oil thermal conductivity, α: viscosity coefficient of viscosity, β: temperature coefficient of viscosity, σ : Strip deformation resistance.

In the present invention, a coagulant for promoting the separation of water and oil in the emulsion is added to the rolling oil, and the ratio of the oil film thickness at the inlet of the plastic working portion to the surface roughness of the work roll is 0. When the supply amount of the rolling oil is controlled so as to be maintained at 3 or more and 3.5 or less, the rolling state can be maintained with extremely high accuracy.

That is, the oil film thickness h ₁ at the inlet of the plastic working portion is
By using the above formulas (1) to (3), the oil film thickness h ₁ can be obtained by using the rolling speed, strip speed, strip deformation resistance, contact arc length, rolling oil viscosity, rolling oil supply amount, etc. as parameters. Since it becomes possible to control, the ratio of the oil film thickness h ₁ at the plastic working portion inlet to the surface roughness Ra of the work roll is set to the optimum value of 0.3 or more, 3.5 or more.
It becomes possible to automatically control the amount of rolling oil supplied so as to maintain the value below, and stable operation is possible under any rolling conditions.

As the aggregating agent applied to the present invention, for example, among the following compounds (A) and (B) proposed by the present inventors in Japanese Patent Publication No. 3-13279, the average molecular weight thereof is 8,000. The oil-soluble polymer compound in the range of 1,000,000 is included.

(A) Homopolymers of nitrogen-containing monomers and salts thereof represented by the following general formulas (I) and (II), or oil-soluble of two or more copolymers thereof. Compound of.

[0022]

[Chemical 1]

[Wherein R ₁ is H or CH ₃ , R ₂ and R 3
₃ represents CH ₃ , C ₂ H ₅ or C ₃ H ₇ . ]

(B) One or more of the nitrogen-containing monomers represented by the general formulas (I) and (II) and salts thereof, and acrylic acid or methacrylic acid, or an alkyl ester or alkylamide thereof. , Or an alkene, or an oil-soluble compound among copolymers with one or more kinds thereof.

The rolling oil may be palm oil, beef tallow or a mixture thereof, and the addition amount of the aggregating agent to the rolling oil may be 0.01% or more, and may be 0.1% or more.
It can be 1% or less.

When the oil film thickness at the plastic working portion inlet is calculated without adding a coagulant to the rolling oil, the plate-out property to the strip is lowered (the amount actually attached to the strip is smaller than the theoretical amount injected). Therefore, the theoretical oil film thickness can be obtained by adding the coagulant.

FIG. 1 shows the reason why it is optimal to set the ratio of the oil film thickness h ₁ at the inlet of the plastic working portion to the surface roughness Ra of the work roll within the above range. This FIG. 1 shows the results obtained by rolling with various changes in the ratio of the oil film thickness at the inlet of the plastic working portion to the surface roughness of the work roll. From this FIG. 1, the above ratio is 0.3 or more, While 3.5 or less is in an appropriate range and a good rolling result was obtained, when the ratio is less than 0.7, seizure failure called heat streak occurs as shown by the solid line, or,
When it exceeds 3.5, slip occurs between the roll and the strip as shown by the broken line, so that stable rolling cannot be performed.

[0028]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 2 is an explanatory view showing a schematic configuration of a rolling oil supply apparatus applied to a rolling oil supply method during cold rolling which is an embodiment according to the present invention.

The rolling oil supply device is provided with a rolling oil tank 20 for storing rolling oil, and an oil feed pump 24 driven by an electric motor 22 to pressurize the rolling oil from the rolling oil tank 20 and send it out. A water tank 26 for storing water,
Water pump 2 for pressurizing and sending out water from the water tank
8, a mixer 30 for mixing water fed by the water pump 28 and rolling oil fed by the oil feeding pump 24, and an emulsion state prepared by mixing water and rolling oil by the mixer 30. And a nozzle 34 for injecting the coolant onto the strip S being rolled by the work roll 32 of the rolling mill ST.

Further, for the electric motor 22 which drives the oil feed pump 24, the oil feed amount command transmission circuit 3 is sent from the computer 36.
A control signal is input and output via 6A, and the rolling condition is input to the computer 36 from the host computer 38 via the rolling condition transmission circuit 38A.

The mixer 30 is installed in the immediate vicinity of the injection nozzle 34. As the mixer 30, an actual flat plate 3-
The enlargement shown in FIG. 3 disclosed in 59033 can be used. Explaining this mixer, a water supply passage 40, a rolling oil supply passage 42, a merging portion 44 for colliding and mixing the water supplied from each of these supply passages with the rolling oil, and water joined by the merging portion 44. And sudden change in cross section 4 to completely mix the oil and the rolling oil to form an emulsion state
6 and a mixed fluid passage 48 having an inner diameter of 6 and a coolant in an emulsion state are sent from the mixed fluid outlet 50 to the nozzle 34.

Next, the operation of this embodiment will be described.

The host computer 38 incorporates rolling conditions such as rolling speed, strip speed, contact arc length, strip deformation resistance, rolling oil viscosity, rolling oil supply amount, roll surface roughness, and the above (1) to (3). Calculate the oil film thickness h ₁ at the plastic working part inlet by solving the simultaneous equations shown in, and keep the ratio of this calculation result and the roll surface roughness Ra constant within the range of 0.3 or more and 3.5 or less. A signal was sent from the computer 36 to the electric motor 22 so as to keep it, and rolling was performed while controlling the oil feed pump 24. The result is shown in FIG.

As is clear from FIG. 4, even when the rolling speed changes with time, according to the method of the present invention, the strip thickness deviation is extremely small and stable rolling is possible. In the figure, the solid line shows the sheet thickness deviation by the method of the present invention, and the broken line shows the sheet thickness deviation by the conventional method.

In this example, the oil-soluble polymer compound (A) obtained by polymerizing a monomer represented by the following chemical formula was used as the coagulant, and the coagulant was added to the rolling oil in an amount of 2%.
00 ppm was added.

[0037]

[Chemical 2]

As described above in detail, according to the present embodiment, it is possible to obtain a good result that the rolling can be performed with a stable plate thickness accuracy even during the rolling acceleration / deceleration or when the material changes. Was given.

Further, according to this embodiment, since it is possible to supply a sufficient amount of rolling oil necessary for stable rolling, the roll life can be extended by, for example, 10%, Moreover, the effect that the rolling oil consumption rate can be reduced by, for example, 15% was also obtained.

Although the present invention has been specifically described above, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the scope of the invention.

For example, it is particularly preferable that the ratio of the oil film thickness at the inlet of the plastic working portion to the surface roughness of the work roll is 0.3 or more and 3.5 or less, but it is not necessarily limited to this.

Further, the coagulant and the addition amount thereof are not limited to those shown in the above embodiment.

Further, in the above embodiment, the case of the direct type rolling oil supply method used for cold rolling has been described, but the present invention is a circulation type for circulating rolling oil or rolling oil used for hot rolling. It goes without saying that it can be applied to the rolling oil supply method.

[0044]

As described above, according to the present invention, it is possible to always maintain a stable rolling state without the need for manual intervention.

[Brief description of drawings]

FIG. 1 is a diagram showing the basis for the numerical limitation of the present invention.

FIG. 2 is an explanatory view showing a rolling oil supply device applied to an embodiment according to the present invention.

FIG. 3 is an enlarged sectional view showing a mixer used in the above embodiment.

FIG. 4 is a diagram showing the relationship between rolling speed and sheet thickness deviation.

FIG. 5 is an explanatory view showing a conventional rolling oil supply device.

[Explanation of symbols]

 20 ... Rolling oil tank 22 ... Electric motor 24 ... Oil pump 26 ... Water tank 28 ... Water pump 30 ... Mixer 32 ... Work roll 34 ... Nozzle 36 ... Calculator 38 ... High-end calculator ST ... Rolling machine S ... Strip

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koji Kawashima, 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Inside the Chiba Works, Kawasaki Steel (72) Tomohiro Kaneko 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Kawasaki Steel Works Co., Ltd. Chiba Works (72) Inventor Yasuhiro Yamada 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Works Chiba Works

Claims (2)

[Claims] 1. A rolling oil supply method in which a rolling oil is mixed with water to form an emulsion when the strip is rolled by a rolling mill and the emulsion is sprayed from a nozzle onto the surface of the strip. A rolling oil supply method, characterized in that a rolling oil supply amount is controlled so as to maintain a ratio of an oil film thickness at an inlet of a processing section to an appropriate value. 2. The rolling oil according to claim 1, wherein a coagulant for promoting the separation of water and oil in the emulsion is added to the rolling oil, and the ratio of the oil film thickness at the inlet of the plastic working portion to the surface roughness of the work roll is set. A rolling oil supply method characterized by maintaining at 0.3 or more and 3.5 or less.