JPS591485B2 - Lubricant supply method in strip rolling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for supplying lubricant when rolling a strip.

When a sl-IJ tube is rolled by, for example, a cold rolling mill, a strip biting portion (hereinafter referred to as roll bite) of a rotating rolling roll is formed on the entry side of the rolling mill.

) and the rolling rolls as well as the strip itself.

The purpose and function of the lubricant injection are as follows.

(1) For lubrication to reduce rolling power in rolling mills.

(2) For cooling the rolling rolls to prevent the rolling rolls from rising in temperature due to processing heat and frictional heat from the strip being rolled.

(3) For strip cooling to prevent strip temperature rise during rolling.

The above-mentioned lubricant is generally a tallow-based or mineral oil-based emulsion with a fat content of about 5%, and is stored in a tank of about 100 to 150 m', for example, installed underground below the rolling mill. Stirring is performed to maintain a uniform fat and oil concentration without separation.

Then, it is supplied from the tank to a rolling mill on the ground by a pump, and after being sprayed onto the roll bite, rolling rolls, and strip itself, it is stored in a pit provided directly below the rolling mill, and then recycled from the pit. It is returned to the tank and used for circulation.

FIG. 1 shows an explanatory diagram of a conventional lubricant supply method.

In the drawing, A is a part of a cold tandem rolling mill, which includes work rolls 2, 2 for rolling the strip 1 to a predetermined thickness and backup rolls for reinforcing the work rolls 2, 2, which run as indicated by the arrows. It consists of 3,3.

4.4 is a plurality of lubricant injection headers provided in the width direction of the strip 1 toward the roll bite of the work rolls 2, 2 on the entrance side of the cold tandem rolling mill A;
, 5 is a header for injecting lubricant, which is provided in plurality in the width direction of the strip 1, and 6 and 6 are respectively provided in the width direction of the strip 1, facing the work roll 2.degree.

The lubricant injected from the headers 4, 4 provided toward the roll bite of the work rolls 2, 2 is supplied to the rolling mill A.
The lubricant injected from the header 5.5 provided toward the work rolls 2, 2 is used to cool the work rolls 2.2, and the lubricant is provided toward the top and bottom surfaces of the strip 1. The lubricant injected from the header 6:6 is for cooling the strip 1.

However, the conventional lubricant and cooling lubricant supply methods described above have the following problems in achieving the desired lubrication and cooling effects.

That is, the lubricating effect is that the oil of the emulsion supplied to the roll bite of the work rolls 2, 2 is separated from the water and spread on the strip 1, and the oil is drawn between the strip 1 and the work rolls 2, 2. This is obtained by

This property of the lubricant is called plate-out property (water syneresis property), and generally, the plate-out amount is expressed as the water syneresis amount per unit area of the strip (9/rr
l).

The plate-out amount has a close relationship with rolling properties, and when the plate-out amount is small, less oil is drawn into the roll bite of the work roll.

Therefore, it is desired to increase the amount of plate out.

The amount of plate-out has a deep relationship with the emulsion stability of the emulsion, and when emulsification is unstable and oil is easily separated from water, the amount of plate-out increases.

. However, on the other hand, if the emulsification of the emulsion becomes unstable, the mixing state of the emulsion in the tank deteriorates, and an emulsion with extremely unstable concentration is supplied to the rolling mill, resulting in unstable rolling and operation. Sexuality is damaged.

Therefore, it is necessary for the emulsion to have a certain degree of emulsion stability, so even if it is desired to increase the amount of plate-out, there is a limit to this and it is difficult to perform stable rolling. They had no choice but to work at line speed, which resulted in lower productivity.

Furthermore, when cooling the strip by injecting the lubricant, it is desirable that the lubricant be as low as possible.

That is, if the strip is insufficiently cooled and its temperature becomes high, burn marks will occur on the strip during rolling, making it impossible to obtain a product with good surface properties.

However, in the conventional lubricant circulation cooling system described above, since the lubricating oil has a high melting point (beef tallow base 30° to 40°),
It is necessary to control the emulsion temperature to be 50° to 70° C. higher, and therefore the cooling effect is considerably lower than when using room temperature water.

Furthermore, since cooling is performed by jetting lubricant, cooling the lower surface of the strip does not provide the same lubricant riding effect as cooling the upper surface, resulting in insufficient cooling. This caused frequent burn-in scratches on the bottom surface of the strip.

As mentioned above, with conventional lubricant supply methods, both the lubrication effect and strip cooling effect were insufficient, making it impossible to obtain products with excellent surface properties through stable rolling operations with high productivity. .

From the above-mentioned viewpoints, this invention provides a lubricant for strip rolling that provides excellent lubrication and cooling effects, and allows products with excellent surface properties to be obtained through stable rolling operations with high productivity. It provides a feeding method, and is provided below the pass line of the traveling strip on the entry side of the Sl-IJ tub rolling mill, parallel to the pass line, and its tip facing directly in front of the rolling roll. A lubricant is supplied into the gutter in the running direction of the strip, and near the tip of the gutter, the oil layer of the lubricant separates and floats to form an oil layer, and the strip runs on the surface of the lubricant. - The IJ tube is characterized in that it passes through the oil layer.

Next, the method of this invention will be explained with reference to FIGS. 2 and 3.

In the method of this invention, on the entry side of the rolling mill A, the strip 1 is placed below the pass line running in the direction of the arrow, parallel to the strip 1, and with its tip facing just in front of the work roll 2. In addition, a gutter 8 of a predetermined length having a width at least wider than the width of the strip 1 is provided, and the gutter 8
The lubricant I is supplied from the upstream side of the gutter 8 as shown by the arrow, flows through the gutter 8, and overflows from the tip facing just in front of the work roll 2 as shown by the arrow, so that the strip 1 is The lubricant 7 flowing in the gutter 8 passes through the surface thereof.

At this time, as the lubricant 7 supplied into the gutter 8 from the upstream side flows to the tip of the gutter 8, the oil layer in the emulsion separates to form an oil layer 7a, and the oil layer 7a is formed on the work roll 2. The closer to the entrance side, the thicker the oil layer 7a becomes.

Therefore, since the strip 1 passing through the surface of the lubricant 7 passes through the separated oil layer Ta, it is rolled with an extremely high plateout amount.
As a result, a sufficient amount of oil is drawn into the roll bite of the work roll, resulting in a highly lubricated state.

Note that 5, 5 is a header that injects lubricant toward the work rolls 2, 2.

Further, in FIG. 3, a plurality of strip cooling lubricant injection headers 9 are provided on the bottom surface of the gutter 8 on the upstream side away from the work rolls 2 and directed toward the lower surface of the running strip 1.

Reference numeral 6 denotes a conventional header for injecting lubricant toward the top surface of the strip, and the lubricant injected from these ensures that the lubricant liquid level in gutter 8 is always above the pass line of strip 1. There is.

When the lubricant is injected from the header 9 toward the lower surface of the strip 1 at a relatively high pressure, the lubricant hits the strip 1 with a high degree of turbulence, resulting in a hot stream.
The temperature boundary layer that develops at the boundary with IJ tube 1 is separated,
A high cooling effect can be obtained.

Figure 4 is a diagram showing the relationship between heat transfer coefficient and strip surface temperature, where the Δ mark indicates the case of turbulent immersion cooling of the present invention, and the ○ mark indicates the case of conventional spray cooling. It is clear from the above that a high cooling effect can be obtained by the cooling method with increased turbulence according to the present invention.

Next, an embodiment of the present invention will be described based on schematic perspective views of FIGS. 5 and 6.

In this example, lubricant was supplied between the fourth and fifth stands of a cold tandem rolling mill consisting of five stands, and the distance between the stands was 4.
It is 4m.

The gutter 8 provided between the stands has a length of 3 m in the line direction from just before the entry side of the fifth stand and a width of 1400 mm, and the height of the side plate 8a of the gutter 8 is 55 mm on the rolling mill side.
On the opposite upstream side, there was 7 territory U, and the area between them was sloped in a straight line.

Incidentally, the distance between the bottom plate of the gutter 8 and the running sl-IJ tube 1 is approximately 50 mm and is constant in the line direction.

The rolling mill side weir plate 8b of the gutter 8 is as shown in FIG.
It is formed in an arc shape from the lower edge to the upper edge,
In order to make it easier to actively draw the overflowing emulsion oil layer into the roll bite, a gap H (20 in this embodiment) is provided between the upper edge of the overflowing emulsion and the upper edge of the side plate 8a. , the lubrication effect due to the overflow of the oil layer is enhanced.

Reference numeral 8c denotes a weir plate provided upstream from the rolling mill to prevent lubricant from flowing out, and the distance between the upper edge of the weir plate 8C and the sl-IJ tube 1 was approximately 20 mm.

A strip cooling lubricant injection header 9 provided on the bottom surface of the gutter 8 on the upstream side from the rolling mill A toward the lower surface of the strip 1 has a jet header 9 of 100 mm as shown in the cross-sectional view in FIG.
A tube, 1400? Xll! Thirteen flat spray nozzles 10 having a length of 1 are provided in the width direction of the gutter 8, and the lubricant is sprayed at an angle of 45 degrees toward the traveling direction of the strip 1.

In this embodiment, the discharge pressure of the lubricant from the header 9 is 10 kg/crit, and the flow rate is 2001/min/header.

As a result of supplying lubricant using the method described above, the amount of plate out was significantly increased compared to the conventional method, and an excellent lubrication effect was obtained.
By being able to reduce the zero coefficient, it has become possible to significantly reduce power consumption.

In addition, the temperature of the strip has been lowered by 20° to 30° compared to the conventional method, and the frequency of seizure scratches on the sl-IJ tube can be reduced to about 30% of the conventional rate, greatly improving the rolling operation. can.

Although the above embodiment describes a cold rolling mill, the method of the present invention can also be applied to a hot rolling mill.
tion method) and direct injection method (Direct injection method).
Appl 1cation method) can also be applied,
A similar effect can be achieved.

As explained above, according to the method of the present invention, excellent lubrication and cooling effects can be obtained, and products with excellent surface properties can be manufactured through stable rolling operations with high productivity. Not only can the power consumption of the machine be significantly reduced, but also the amount of lubricant consumed can be reduced, resulting in excellent industrial effects.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a conventional lubricant supply method, FIGS. 2 and 3 are explanatory diagrams showing a lubricant supply method of the present invention,
Fig. 4 is a diagram showing the relationship between heat transfer coefficient and IJ tube surface temperature, Figs. 5 and 6 are schematic trunk views of the inlet side part of a rolling mill showing an embodiment of the present invention, and Fig. 7 5 is a sectional view taken along the line A-A in FIG. In the drawings, A...Rolling mill, 1...
Stritz, 2... Work roll, 3...
... Backup roll, 4, 5, 6 ... Header, 7 ... Lubricant, 8 ... Gutter, 8a
...Side plate, 8b, 8c...Weir board,
9...Header, 10...Spray nozzle.

Claims (1)

[Claims] 1. The running strip is placed in a gutter parallel to the pass line, which is provided below the pass line of the running strip on the entry side of the Sl-IJ tube rolling mill, and whose tip faces directly in front of the rolling roll. A lubricant is supplied toward the direction of the gutter, and an oil layer of the lubricant separates and floats to form an oil layer near the tip of the gutter, and a strip running on the surface of the lubricant passes through the oil layer. A method for supplying lubricant in strip rolling, characterized in that: