JP2774201B2 - Work roll cooling method for cold rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cooling a work roll of a cold rolling mill employing a direct type rolling oil supply system for separately injecting lubricant and cooling water coolant.

[0002]

2. Description of the Related Art Generally, a work roll of a cold rolling mill employing a direct type rolling oil supply system is cooled by applying a coolant from a roll exit side. This is because, by cooling the work roll from the outlet side, the cooling efficiency of the roll is increased, the flow rate of the coolant is reduced, and the rise of the roll temperature is suppressed, so that the shape of the rolled plate is improved.

[0003]

However, in such a method of cooling the work roll only from the exit side of the rolling mill,
The rise in sheet temperature during rolling causes an increase in the rate of heat streaks, a reduction in rolling speed, and a rapid decrease in roll roughness. There were various problems, such as not being washed away and seizure flaws and dent flaws on the steel strip surface increased.

[0004] The present invention has solved such problems.
An object of the present invention is to provide a work roll cooling method for a cold rolling mill employing a direct type rolling oil supply system.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a work roll cooling method for a cold rolling mill employing a direct type rolling oil supply system for separately jetting lubricating oil and cooling water as a coolant. From both the inlet and outlet sides, adjust the ratio of inlet coolant flow rate to outlet coolant flow rate by 30.
± 15%: A method for cooling a work roll of a cold rolling mill, characterized in that roll cooling is performed so that the inlet-side coolant cleans the inlet-side plate surface.

[0006]

First, the results of experiments performed by the present inventors will be described. FIG. 2 (a) is a diagram showing the relationship between the rolling speed and the outlet plate temperature when using cooling water as the coolant and only the outlet coolant when cooling the work roll of the cold rolling mill. Means that the average plate temperature is 137.6 ° C (n = 449)
Met. FIG. 2 (b) is a diagram showing the relationship between the rolling speed and the outlet sheet temperature when the inlet side coolant is installed and only this is used. In this case, the average sheet temperature is 130.9 ° C (n =
119). A comparison between the two shows that the average sheet temperature of the outlet side is lower by about 7 ° C. when only the coolant on the inlet side is used than when only the coolant on the outlet side is used.

FIG. 3 shows the relationship between the outlet sheet temperature and the occurrence rate of heat streak. From FIG. 3, it can be seen that the lower the sheet temperature, the lower the rate of occurrence of heat streaks.
FIG. 4A shows the roll mark generation rate when only the outgoing coolant is used, and FIG. 4B shows the roll mark generation rate when only the incoming coolant is used. The roll mark generation rate is lower when only the inlet side coolant is used.

The present invention reduces the temperature of the rolled sheet and reduces the rolling speed by using the incoming coolant together with the conventional outgoing coolant, utilizing the advantages of the incoming coolant found through the above experiments. The goal is to increase it. Here, by setting the flow ratio of the coolant on the inlet side and the coolant on the outlet side to 30 ± 15%: 70 ± 15%, the mutual advantage can be obtained without impairing the advantages of using the coolant on the inlet side and the coolant on the outlet side. Can be overcome.
The outlet coolant flow rate should not be affected by the cooling effect.
A flow rate of about 70% must be secured, and if the inlet coolant flow rate is set to 45% or more, the rolling oil applied to the plate surface will flow. preferable.

The injection pressure of the inlet coolant is preferably 5 kg / cm ² or less so that the rolling oil applied to the plate surface does not flow.

[0010]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of one embodiment of the present invention. In FIG. 1, 1a and 1b are upper and lower work rolls, 2a and 2b are upper and lower backup rolls, and 3 is a cold rolled steel strip. Reference numeral 4 denotes an incoming coolant injection device, 5 denotes an outgoing coolant injection device, 6 denotes a steel strip coolant injection device, and 7 denotes a palm oil injection device.

Thus, the cooling water is injected from both the inlet-side coolant ejecting device 4 and the outlet-side coolant ejecting device 5 onto the upper and lower work rolls 1a and 1b to perform roll cooling. At this time, on the entry side, roll cooling is performed so that the coolant cleans the entry side plate surface. Next, specific examples of the present invention will be described. By carrying out the work roll cooling method of the present invention for cooling the work roll of the No. 6 stand of the 6-stand cold rolling mill employing the direct rolling oil system, the exit side sheet temperature decreases by an average of 10 ° C. The maximum rolling speed could be increased by 260 mpm, and the throughput per work roll increased by 500 tons. The number of occurrences of roll marks is
As shown in Table 1, it decreased significantly. However, the survey period is 11 days each.

[0012]

[0013]

According to the present invention, in the method of cooling a roll of a cold rolling mill, the temperature of a rolled sheet is reduced by utilizing the advantages of an incoming coolant and using it together with a conventional outgoing coolant. Can be increased, and a decrease in the roughness of the roll can be suppressed. This also increases production efficiency.

Further, since the cleaning effect of the inlet side plate surface is enhanced,
The rate of occurrence of roll marks such as seizure, heat streak, and flaws is also extremely low, and the quality of rolled products is also improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between each rolling speed and an outlet sheet temperature when an outlet coolant or an inlet coolant is used.

FIG. 3 is a diagram showing a relationship between a delivery sheet temperature and a heat streak.

FIG. 4 is a diagram showing the respective roll mark occurrence rates when an outgoing coolant or an incoming coolant is used.

[Description of Signs] 1a Upper work roll 1b Lower work roll 2a Upper backup roll 2b Lower backup roll 3 Cold rolled steel strip 4 Inlet coolant injection device 5 Outlet coolant injection device 6 Steel strip coolant 7 Palm oil injection device

──────────────────────────────────────────────────の Continuation of the front page (72) Inventor Kenji Ueda 1 Kawasaki-cho, Chiba-shi, Chiba Prefecture Kawasaki Steel Corporation Chiba Works (56) References JP-A-1-99709 -24888 (JP, B2) (58) Fields surveyed (Int. Cl. ⁶ , DB name) B21B 27/10

Claims (1)

(57) [Claims] In a method for cooling a work roll of a cold rolling mill employing a direct type rolling oil supply system in which a lubricating oil and a cooling water as a coolant are separately injected, the work roll is cooled from both the entrance side and the exit side of the work roll. Cold rolling, wherein the ratio of the flow rate of the coolant on the inlet side to the flow rate of the coolant on the outlet side is 30 ± 15%: 70 ± 15%, and roll cooling is performed so that the coolant on the inlet side cleans the plate surface on the inlet side. Machine work roll cooling method.