JP2000280002A - Cold tandem rolling method of strip and cold tandem rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a rise in coefficient of friction in a low-speed rolling area and reduce rolling load by rolling with a reduced supply amount of inlet- side roll coolant in accordance with the rolling speed. SOLUTION: A cold strip 3 is rolled with a cold tandem rolling mill. Lubricating oil is supplied to the cold strip 3 by means of a lubricating oil spraying equipment (palm oil spraying equipment) 7. An entry-side roll coolant spraying equipment 4 is installed at a place closer to the stand than the lubricating oil spraying equipment (palm oil spraying equipment) 7 and exit-side roll coolant spraying equipment 5 is installed on the exit side of the stand. By means of the entry-side and exit-side roll coolant spraying equipment 4 and 5, the upper and lower work rolls 1a and 1b are cooled. An entry-side roll coolant supply amount controller 11 changes the flow rate by outputting opening adjusting command to an entry-side roll coolant flow control valve 10 in accordance with the rolling speed. For example, the supply amount of the entry-side roll coolant is made to be 0% at the rolling speed of 400 m/min or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold tandem rolling method and a cold tandem rolling mill employing a direct rolling oil supply system for separately supplying lubricating oil and roll coolant.

[0002]

2. Description of the Related Art A direct rolling oil supply system for separately supplying lubricating oil and roll coolant has good rolling lubricity and work roll cooling ability. It is applied to a cold tandem rolling mill that rolls a strip at high speed. This cold tandem rolling mill has a plurality of stands having work rolls arranged in series, and usually includes 5 to 6 stands.

[0003] As a cold tandem rolling mill employing this direct type rolling oil supply system, there are a type that injects a roll coolant to a work roll from an outlet side of a stand and a type that injects a roll coolant from both an inlet side and an outlet side. Are known.
Further, the roll coolant may be directly sprayed on the work roll, may be sprayed on the roll bite portion, or may be sprayed on both of them. In general, water is often used as a roll coolant, while as a lubricating oil, it is common to dilute rolling oil with warm water or the like and directly spray it onto a cold-rolled strip.

For example, Japanese Patent Application Laid-Open No. 4-253512 discloses that
A stand of a cold tandem rolling mill shown in FIG. 9 for the purpose of increasing cooling efficiency and reducing surface defects to enable high-speed rolling is disclosed. The stand of the cold tandem rolling mill described in Japanese Patent Application Laid-Open No. 4-253512 has upper and lower work rolls 1a and 1b and upper and lower backup rolls.
A stand having 2a and 2b, wherein a lubricating oil injection device 7 is provided on the entrance side of the stand to inject lubricating oil to the cold rolled strip 3 and closer to the entrance side of the stand than the lubricating oil injection device 7 Is provided with an inlet-side roll coolant injector 4 and an outlet-side roll coolant injector 5 is provided on the outlet side of the stand to roll the cold-rolled strip 3 while cooling the work rolls 1a and 1b with water.

[0005]

In recent years, the rolling speed of a cold tandem rolling mill has tended to increase from the viewpoint of production efficiency. For example, in a cold tandem rolling mill for producing a cold-rolled steel strip, the maximum rolling speed is 2000 m. Those exceeding / min are no longer uncommon. However, if the lubrication / cooling system is designed in accordance with such high-speed tandem rolling, when the rolling speed is reduced, for example, at the time of changing a cold-rolled strip, the gap between the roll and the strip at a predetermined rolling speed or less is reduced. A phenomenon occurs in which the coefficient of friction increases. Such an increase in the coefficient of friction causes an increase in the rolling load, and therefore causes problems such as a tendency of the strip to have a defective shape.

It is generally considered that the increase in the coefficient of friction due to the decrease in the rolling speed is caused by the difficulty in introducing the lubricating oil into the biting portion due to the decrease in the rotation speed of the roll and the transport speed of the cold rolled strip. Although the above phenomenon was considered to be based on the same cause, the increase in the friction coefficient in the low-speed rolling region was not improved even if the supply amount of the lubricating oil was simply increased, and was difficult to avoid.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a cold tandem rolling method and a cold tandem rolling mill capable of reducing a rolling load at a predetermined rolling speed or less. It is in.

[0008]

As a result of various analyzes of the above phenomena, the present inventors have found that, besides the conventionally known friction coefficient increasing mechanism, the phenomenon that the lubricating oil is pushed back by the roll coolant when the rolling speed is reduced. Have been found to be greatly involved, and have led to the present invention. That is, the present invention provides at least one or more stands of a cold tandem rolling mill, wherein lubricating oil is supplied to the strip at the entry side of the stand, and entry roll coolant is supplied to the work rolls of the stand. In the method of cold tandem rolling of a sheet, at least one or more of the stands has a rolling speed of not more than a predetermined value, and the supply amount of the inlet roll coolant at a predetermined value or less is determined according to the rolling speed. Is less than the supply amount of the entry-side roll coolant when the value exceeds the predetermined value, thereby performing a cold tandem rolling method for a strip.

Further, the supply amount of the lubricating oil when the rolling speed is equal to or lower than a predetermined value is increased according to the rolling speed, more than the supply amount of the lubricating oil when the rolling speed exceeds a predetermined value. Is preferred. Further, at least one or more stands of a cold tandem rolling mill, a lubricating oil injection device provided on the entrance side of the stand, and an inlet roll coolant provided closer to the entrance side of the rolling mill than the lubricating oil injection device. A cold tandem rolling mill including an injection device, a lubricating oil supply pump for supplying lubricating oil to the lubricating oil injection device, and a roll coolant supply pump for supplying roll coolant to the inlet roll coolant injection device. At least one or more of the stands is provided with an inlet roll coolant flow control valve in the middle of a piping route from the roll coolant supply pump to the inlet roll coolant injector, and a rolling speed Characterized in that an inlet roll coolant supply amount control device that outputs an opening command of the inlet roll coolant flow rate adjusting valve according to It is a tandem cold rolling mill of the strip to be.

In addition, a lubricating oil flow control valve is provided in the middle of a piping route from the lubricating oil supply pump to the lubricating oil injection device, and an opening command of the lubricating oil flow adjusting valve is output according to a rolling speed. It is preferable to provide a lubricating oil supply control device. The predetermined value of the rolling speed of the present invention varies depending on the stand, and may be changed depending on the rolled material,
300 to 80 at the final stand of the cold tandem rolling mill
It is preferably in the range of 0 m / min.

In the present invention, it is assumed that the supply amount of the inlet roll coolant is reduced to zero.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The cold tandem rolling mill of the present invention mainly has a finished plate thickness of 0.35 mm or less, preferably
Rolling a cold rolled steel sheet such as a tinplate sheet or a galvanized sheet sheet of 0.25 mm or less will be described in detail by taking as an example a case where the present invention is applied to one stand as shown in FIG. FIG. 1 shows a sixth stand (final stand) of a six-stand cold tandem rolling mill, in which a cold-rolled steel strip 3 is rolled from left to right. In the drawing, the same components as those of the stand of the conventional cold tandem rolling mill are denoted by the same reference numerals, and those described in the related art are not described in detail.

However, the roll coolant control valve 8 controls the total amount of roll coolant supplied to the entrance and exit of the roll. The ratio of the supply amount of the inlet-side roll coolant and the supply amount of the outlet-side roll coolant is adjusted by adjusting the inlet-side roll coolant supply amount to adjust the inlet-side roll coolant supply amount. Instead, an adjusting valve or the like for controlling the outlet coolant flow rate may be provided.

Further, the roll coolant supply pump 9 includes:
The injection pressure of the inlet-side roll coolant injector 4 and the outlet-side roll coolant injector 5 is set to a predetermined pressure, and constant roll coolant is supplied to the inlet-side roll coolant injector 4 and the outlet-side roll coolant injector 5 at a predetermined pressure. It is a pump. Reference numeral 10 denotes an inlet roll coolant flow rate adjusting valve for adjusting the inlet roll coolant supply amount of the inlet roll coolant injection device 4 as described above, and 11 denotes opening of the inlet roll coolant flow rate adjusting valve 10 in accordance with the rolling speed. It is an inlet roll coolant supply amount control device that outputs a degree command. As shown in FIG. 2 (a), for example, as shown in FIG. The pattern of the opening degree command for setting the amount to 0% is incorporated in advance.

Reference numeral 12 denotes a lubricating oil flow control valve for adjusting the lubricating oil supply amount of the lubricating oil injection device, and reference numeral 13 denotes a lubricating oil supply control device for outputting an opening command of the lubricating oil flow adjusting valve 12.
For example, as shown by the solid line in FIG. 2 (b), the lubricating oil supply amount control device 13 increases the lubricating oil supply amount at 400 m / min or less according to the rolling speed, Against 30
A pattern of the opening command to increase to 110% at 0 m / min and to 400% immediately before stopping is pre-installed. Or
As shown by the broken line in FIG. 2B, a pattern of the opening degree command for keeping the lubricating oil supply amount constant is incorporated in advance.

The cold tandem rolling mill according to the present invention is characterized in that an inlet-side roll coolant flow rate adjusting valve 10 is provided in the middle of a piping route from the roll coolant supply pump 9 to the inlet-side roll coolant injector 4. Install and adjust the inlet roll coolant flow rate control valve according to the rolling speed
By providing the inlet roll coolant supply amount control device 11 that outputs the opening degree command of 10 to the stand, the supply amount of the inlet roll coolant at a predetermined rolling speed or less is adjusted to a predetermined rolling speed according to the rolling speed. That is, the rolling load at a predetermined rolling speed or less is reduced by decreasing the supply amount of the inlet-side roll coolant in the case of exceeding.

Further, in the stand of the cold tandem rolling mill according to the present invention, a lubricating oil flow control valve 12 is provided in the middle of the piping route from the lubricating oil supply pump to the lubricating oil injection device 7, and the lubricating oil flow adjusting valve 12 is provided depending on the rolling speed. By providing a lubricating oil supply amount control device 13 that outputs an opening degree command of the lubricating oil flow control valve 12, the lubricating oil supply amount at a predetermined rolling speed or less is adjusted to a predetermined rolling speed according to the rolling speed. The rolling load at a predetermined rolling speed or lower may be reduced by increasing the supply amount of the lubricating oil when it exceeds the predetermined value.

In the stand of the cold tandem rolling mill according to the present invention shown in FIG. 1, since the total amount of coolant supplied on the inlet side and the outlet side is substantially constant by the roll coolant flow rate control valve 8, the inlet side is controlled. Even if the amount of the roll coolant decreases, the flow rate flowing to the outlet side increases, and the surface defect of the cold-rolled steel strip caused by the temperature rise of the work roll can be prevented. If necessary, the roll coolant flow control valve 8
May be controlled in accordance with the setting change of the inlet roll coolant flow rate control valve 10 to control the total flow rate more precisely, or by providing a control valve and a feed rate control device for adjusting the outlet roll coolant flow rate. Alternatively, the flow rate of the outlet roll coolant may be directly controlled.

As described above, in the stand of the cold tandem rolling mill according to the present invention, the supply amount of the inlet roll coolant at a predetermined speed or less is adjusted according to the rolling speed when the inlet roll coolant exceeds the predetermined rolling speed. When decreasing the supply amount of the roll coolant, it is desirable to increase the flow rate of the outlet roll coolant to an extent that compensates for the decrease. In the sixth stand of the cold tandem rolling mill of the present invention, for example, as shown in FIG. 3, the steady rolling speed exceeds 2000 m / min, and the cutting (shear cutting) of the cold rolled steel strip is performed at a low speed of 200 m / min. It is intended to be applied. As described above, in a cold tandem rolling mill that rolls a tin plate having a finished plate thickness of 0.35 mm or less, preferably 0.25 mm or less at a high rolling speed exceeding 2000 m / min, the rolling load increases and the shape starts to deteriorate. The rolling speed is in the range of 300 to 800 m / min, depending on the type of steel and the thickness of the finished plate. Therefore, the predetermined rolling speed is preferably set within a range of 300 to 800 m / min.

The lubricating oil used in the present invention may be a rolling lubricating oil capable of high-speed rolling of a thin tin plate or a thin zinc-plated plate with good surface quality, and is preferably a base oil based on palm oil, tallow or synthetic ester. preferable. According to the rolling speed, the supply amount of the inlet roll coolant at a predetermined rolling speed or less, which is a feature of the present invention, is reduced from the supply amount of the inlet roll coolant when the predetermined rolling speed is exceeded, and The reason why the rolling load at the rolling speed or lower can be reduced is considered as follows.

FIG. 5 (b) shows the distribution of the lubricating oil and the inlet roll coolant on the cold-rolled strip when rolling at a speed higher than a predetermined rolling speed. A region where the side roll coolant mainly distributes, 15 is a region where the lubricating oil is mainly distributed, and 16 is a mixing region where the input side roll coolant and the lubricating oil are mixed in the same amount. It goes without saying that, for example, the lubricating oil remains on the strip while the amount is reduced also in the region 14.

Under rolling at a speed higher than a predetermined rolling speed, the inlet roll coolant is conveyed to a cold-rolled strip moving at a high speed and conveyed to a roll biting portion. For this reason, the inlet roll coolant is distributed only near the roll as shown in FIG. 5 (b), so that a sufficient amount of lubricating oil is supplied to the roll biting portion. On the other hand, if the rolling speed is reduced to a predetermined rolling speed or less without changing the supply amount of the inlet roll coolant, the effect of transporting the inlet roll coolant to the biting portion of the roll is weakened. Thus, the distribution area of the roll coolant expands in the direction of the lubricant injection device. As a result, even if the injection amount of the lubricating oil is increased, most of the lubricating oil is washed away by the inlet roll coolant before reaching the roll biting portion, so that the friction coefficient is significantly increased.

In the present invention, the supply amount of the inlet roll coolant at a predetermined rolling speed or less is determined according to the rolling speed.
By reducing the supply amount of the inlet roll coolant when the rolling speed exceeds a predetermined value and approaching the distribution at a high speed (when exceeding the predetermined rolling speed) shown in FIG. Because it spreads sufficiently to the biting portion, the coefficient of friction decreases and the rolling load decreases.

Even if the distribution of the inlet roll coolant and the like is improved as described above, since the supply amount of the lubricating oil to the biting portion is also reduced due to the reduction in the rolling speed itself, the increase in the friction coefficient is accordingly reduced. Although not eliminated, this further depends on the supply rate of the lubricating oil at a predetermined rolling speed or less according to the rolling speed,
It is possible to improve the lubricating oil when the rolling speed exceeds a predetermined rolling speed by supplying the lubricating oil at a larger amount than the supplied amount. As described above, almost no effect can be obtained unless the increase of the lubricating oil is performed together with the improvement of the distribution of the roll coolant and the like.

In the above description, the present invention has been described as being applied to the sixth stand (final stand) of a cold tandem rolling mill. However, the present invention can be applied to other stands and may be applied to a plurality of stands. . When the present invention is applied to a plurality of stands, it is preferable to include the final stand because the rolling load at the final stand is significantly increased and the shape is easily deteriorated.

The opening command pattern to be incorporated in the inlet roll coolant supply amount control device 11 is different from the opening command pattern shown in FIG. May be a constant linear shape or a curved shape shown in FIG. As the opening degree command pattern of the supply amount of the inlet roll coolant, the curved shape shown in FIG. 8A having no discontinuity is preferable because the operation is stabilized.

The opening command pattern to be incorporated in the lubricating oil supply amount control device 13 is different from the stepped pattern shown in FIG. 6B or the three-step pattern shown in FIG. Two straight lines (200
(The inclination is different even within the range of up to 500 m / min.) Or a curved shape shown in FIG. As the lubricating oil supply amount opening degree command pattern, the curve shape shown in FIG. 8B without any discontinuity is preferable because the operation is stabilized.

[0028]

(Example 1) Using a cold tandem rolling mill provided with the above-described stand of the present invention in a sixth stand (final stand), a band is formed on the entrance side of the rolling mills of the first to sixth stands. The rolling speed of the sixth stand (final stand) was increased to 2,000 m / min while supplying palm oil to the plate and supplying the inlet roll coolant, which is cooling water, to the work roll closer to the inlet of the rolling mill. The speed was reduced to 300 m / min from the steady speed exceeding the limit. The strip was a base plate for a tin plate having a thickness of 2.0 mm and was rolled to a thickness of 0.18 mm by a cold tandem rolling mill.

At this time, the supply amount of the inlet roll coolant of the rolling mill of the sixth stand (final stand) is set as a supply pattern of the inlet roll coolant according to the rolling speed shown in FIG. And FIG. 4 shows the result of measuring the rolling load of the sixth stand at a speed of 300 m / min or less at a predetermined rolling speed or less, and calculating the friction coefficient from the rolling load formula of HILL based on the rolling load.

However, the roll coolant flow control valve 8 was adjusted so that the total supply amount of the inlet roll coolant and the supply amount of the outlet roll coolant did not change. In addition, the palm oil supply amount is set to two conditions of a solid line and a broken line shown in FIG. 2 (b), and the palm oil supply amount when the rolling speed exceeds 400m / min is set as the set supply amount, and the rolling speed at a rolling speed of 300m / min. Palm oil supply was set to 100% and 110% of the set supply.

On the other hand, as a conventional example, the inlet roll coolant supply control device 11 of the sixth stand was changed so that the inlet roll coolant supply was constant regardless of the rolling speed (when the rolling speed exceeded 400 m / min). In this case, the supply amount of the inlet roll coolant was set to 100%.)
FIG. 4 also shows the results of rolling a tinplate dimensional sheet having the same dimensions and determining the friction coefficient in the same manner.

From these results, it can be seen that the supply amount of the inlet roll coolant at a predetermined rolling speed or less according to the present invention is reduced according to the rolling speed, compared with the supply amount of the inlet roll coolant when the predetermined rolling speed is exceeded. It can be seen that by performing rolling, the friction coefficient at a predetermined rolling speed or less can be reduced and the rolling load can be reduced as compared with the conventional example. Further, by increasing the supply amount of palm oil at a predetermined rolling speed or less according to the present invention in accordance with the rolling speed than the supply amount of palm oil when the predetermined rolling speed is exceeded, a predetermined rolling speed is further increased. It can be seen that the friction coefficient below can be reduced and the rolling load can be reduced.

Therefore, according to the present invention, there is an effect that a tin plate having a good shape can be obtained at a predetermined rolling speed or less. (Example 2) Using the same cold tandem rolling mill as in Example 1, palm oil was supplied to the strip at the entry side of the rolling mills of the first to sixth stands, and further, the entry side of the rolling mill. While supplying the inlet roll coolant, which is cooling water, to the work roll nearby, the rolling speed pattern (2000
The rolling speed is reduced from the steady rolling speed exceeding m / min to 200m
Shear cut at / min and accelerate to a steady rolling speed. ), A 2.2 mm thick base plate for tinplate is finished to a thickness of 0.
It was rolled to 24 mm and wound up into a coil (single weight about 10 ton).

At that time, every 10 coils (the unit weight is the same as above)
The supply amount of the inlet roll coolant of the rolling mill at the sixth stand is the supply amount of the inlet roll coolant shown in Table 1 (the supply amount of the inlet roll coolant when the rolling speed exceeds 800 m / min is the same). It rolled as the pattern column, and it was set as the invention example. On the other hand, as a conventional example, the inlet roll coolant supply amount control device 11 of the sixth stand was changed so that the inlet roll coolant supply amount (the inlet roll coolant of the above-described invention example when the rolling speed exceeded 800 m / min). The same material as in the above-mentioned invention example,
The original tin plate having the same dimensions was rolled by the same number of coils.

However, the pattern of the palm oil supply amount and the supply amount of the outlet roll coolant are as shown in the column of the palm oil supply amount pattern in Table 1 and the outlet roll coolant column in Table 1. Insufficient shape of invention example (steepness 1.5% or more)
Table 1 shows the yield loss due to the comparison with the conventional example.

[0036]

[Table 1]

From these results, it is found that the supply amount of the inlet roll coolant at a predetermined rolling speed or less according to the present invention is reduced in accordance with the rolling speed from the supply amount of the inlet roll coolant when the predetermined rolling speed is exceeded. It can be seen that the yield is improved by performing rolling in comparison with the conventional example. Further, according to the present invention, by increasing the supply amount of the lubricating oil at a predetermined rolling speed or less in accordance with the rolling speed and increasing the supply amount of the lubricating oil when the rolling speed exceeds the predetermined rolling speed, the rolling is further reduced. It can be seen that can be improved.

Further, it is found that it is preferable to increase the supply amount of the outgoing roll coolant by a reduced amount of the incoming roll coolant at a predetermined rolling speed or less because the yield can be further improved.

[0039]

As described above, according to the present invention, since the rolling load at a predetermined rolling speed or less can be reduced, a strip having a good shape can be obtained, and the yield of the strip can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a stand of a cold tandem rolling mill according to the present invention.

FIG. 2 (a) is a graph showing an opening command pattern of an inlet roll coolant supply amount used in the present invention. FIG.
(b) is a graph showing a lubricating oil supply amount opening degree command pattern used in the present invention.

FIG. 3 is a graph showing a rolling speed pattern used in the present invention.

FIG. 4 is a graph showing the effect of the present invention example in comparison with the conventional example.

FIG. 5 is a schematic plan view illustrating the principle of the present invention.

FIG. 6 (a) is a graph showing an opening command pattern of an inlet roll coolant supply amount different from FIG. 2 (a) used in the present invention. FIG. 6B is a graph showing another lubricating oil supply amount opening degree command pattern different from FIG. 2B used in the present invention.

FIG. 7 (a) is a graph showing an opening command pattern of the inlet roll coolant supply amount different from FIG. 2 (a) used in the present invention. FIG. 7 (b) is a graph showing another lubricating oil supply amount opening degree command pattern different from FIG. 2 (b) used in the present invention.

FIG. 8 (a) is a graph showing an opening command pattern of the inlet roll coolant supply amount different from FIG. 2 (a) used in the present invention. FIG. 8B is a graph showing an opening command pattern of the lubricating oil supply amount different from that of FIG. 2B used in the present invention.

FIG. 9 is a schematic configuration diagram of a stand of a conventional cold tandem rolling mill.

[Explanation of symbols]

 1a Upper work roll 1b Upper work roll 2a Upper backup roll 2b Lower backup roll 3 Cold rolled steel strip 4 Inlet roll coolant injector 5 Outlet roll coolant injector 6 Steel strip coolant injector 7 Lubricating oil injector (palm oil injector) Equipment) 8 Roll coolant flow control valve 9 Roll coolant supply pump 10 Inlet roll coolant flow control valve 11 Inlet roll coolant supply control device 12 Lubricating oil flow control valve (palm oil flow control valve) 13 Lubricating oil supply control device (Palm oil supply control device) 14 Inlet roll coolant 15 Lubricating oil (palm oil) 16 Mixing area of inlet roll coolant and lubricating oil

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hidenori Miyake 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba F-term in the Chiba Works of Kawasaki Steel Corporation (reference) 4E002 AD05 BA01 BC02 BC08 BD07

Claims (4)

[Claims] 1. At least one or more stands of a cold tandem rolling mill, wherein lubricating oil is supplied to the strip at the entry side of the stand, and entry roll coolant is supplied to the work rolls of the stand. In the method of cold tandem rolling, at least one or more of the stands, the rolling speed is the supply amount of the inlet roll coolant at a predetermined value or less according to the rolling speed, the rolling speed is A cold tandem rolling method for a strip, characterized in that the rolling is performed while reducing the supply amount of the inlet-side roll coolant when the predetermined value is exceeded. 2. The supply amount of the lubricating oil when the rolling speed is equal to or less than a predetermined value is increased according to the rolling speed, more than the supply amount of the lubricating oil when the rolling speed exceeds the predetermined value. The cold tandem rolling method for a strip according to claim 1, wherein the strip is rolled. 3. A lubricating oil injection device provided on at least one of the stands of the cold tandem rolling mill, and a lubricating oil injection device provided closer to the entrance of the rolling mill than the lubricating oil injection device. A cold tandem including a side roll coolant injection device, a lubricating oil supply pump for feeding lubricating oil to the lubricating oil injection device, and a roll coolant supply pump for feeding roll coolant to the inlet roll coolant injection device In a rolling mill, at least one or more of the stands is provided with an inlet roll coolant flow rate adjustment valve in the middle of a piping route from the roll coolant supply pump to the inlet roll coolant injector. And an inlet roll coolant supply amount control device that outputs an opening command of the inlet roll coolant flow rate adjusting valve according to the rolling speed. A tandem cold rolling mill for strip. 4. A lubricating oil flow control valve is provided in the middle of a piping route from the lubricating oil supply pump to the lubricating oil injection device, and an opening command of the lubricating oil flow adjusting valve is output according to a rolling speed. The cold tandem rolling mill for strips according to claim 3, further comprising a lubricating oil supply amount control device.