JPH0768303A - Method for cold-rolling metallic strip - Google Patents

Abstract

PURPOSE:To lower a rolling load and to improve rolling efficiency by detecting the temperature of a strip metal during rolling and controlling the flow rate of coolant or a rolling speed so that the temperature of this strip metal is as high as possible within a range not exceeding the target value. CONSTITUTION:The plate temperature in that pass is detected directly by a thermometer and, when the temperature is lower than the maximum value of the plate temperature obtained from the deformation previously, the amount of coolant is controlled or the rolling speed is increased when the other condition (whether there is a possibility of a bad form, plate braking and the like) is permitted. On the contrary, when the plate temperature is higher than the maximum value of the plate temperature obtained previously, the amount of coolant is increased or the rolling speed is controlled. In this way, since the rolling is always carried out in the optimum condition in the maximum value of the plate temperature and the rolling reduction by one pass can be increased, the number of rolling passes decreases and the rolling efficiency is improved. Further, the amount of thermal crowm is fixed and the surface property of the steel strip is stabilized as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cold rolling a metal strip, and more particularly to a method for cold rolling a metal strip in which the strip temperature of the metal strip is adjusted to enhance the rolling efficiency.

[0002]

2. Description of the Related Art Conventionally, for example, in cold rolling of a stainless steel strip in a reverse rolling mill, the supply amount of roll coolant and strip coolant is determined from the upper limit of the plate temperature with respect to the maximum value of the rolling speed, and supplied as a constant amount. Was being done. Therefore, in the pass where the rolling speed does not reach the maximum value, the roll coolant and strip coolant become over-supplied, the plate temperature decreases, the deformation resistance of the plate increases, and the specified rolling plate thickness does not reach the prescribed number of passes. However, the optimum pass schedule that maximizes the rolling efficiency has not been realized. In particular, in the case of austenitic stainless steel, hardening is severe due to the unique phenomenon that induced martensite occurs when the plate temperature decreases, so according to JP-A-2-220701, the coolant flow rate is changed for each rolling pass. There has been proposed a rolling method in which unnecessary cooling is not performed. JP-A-2-220701
Pass schedule and plate temperature,
The amount of coolant is shown in Table 1. This is the mother board thickness 4.0
mm austenitic stainless steel (SUS304) 0.8 mm
This is an example of rolling into a sheet having a width of 1023 mm.

[0003]

[Table 1]

According to this rolling method, rolling is performed while changing the amount of coolant in each pass to a predetermined optimum amount, but there is still variation in the range of 90 to 180 ° C. in view of the plate temperature, and the optimum It cannot be said that rolling is performed under the conditions. The thickness of the mother plate, the deformation resistance of the mother plate, the stop time between passes, etc. may vary slightly from coil to coil, and it is considered that such a difference in plate temperature is occurring. Inevitably it will be a lot.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above problems and keeps the sheet temperature as high as possible unless quality problems occur, and always achieves efficient rolling under optimal conditions. The purpose is to provide a method.

[0006]

According to the present invention, in a method for cold rolling a metal strip, the temperature of the metal strip during rolling is detected, and the temperature of the metal strip becomes as high as possible within a range not exceeding a target value. The method for cold rolling a metal strip is characterized by adjusting the coolant flow rate or rolling speed as described above.

[0007]

[Operation] According to the present invention, the plate temperature in the pass is directly detected by a thermometer, and if the plate temperature is lower than the maximum value previously obtained from the deformation resistance, the amount of coolant is limited or If the above conditions (whether there is a risk of defective shape, strip breakage, etc.) are allowed, increase the rolling speed. On the contrary, when the detected sheet temperature is higher than the maximum value of the sheet temperature obtained in advance, the amount of coolant is increased or the rolling speed is limited. In this way, it is possible to always achieve the optimum conditions of rolling at the maximum plate temperature and increase the amount of reduction per pass, thus reducing the number of rolling passes and improving rolling efficiency.

[0008]

EXAMPLE An example of the rolling method of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a cold rolling facility according to this embodiment. 1 is a tension reel, 2 is a deflector roll, 3 is a rolling mill, 4 is a strip coolant nozzle,
Reference numeral 5 is a roll coolant nozzle, 6 is a thermometer, and S is a steel strip. The steel strip S is rolled up and down between the left and right tension reels 1 and 1 by a rolling mill 3 to a predetermined size. The strip coolant nozzle 4 and the roll coolant nozzle 5 are provided on the same side of the top, bottom, left and right, and either the left side or the right side is switched and used depending on the rolling direction.

FIG. 2 is a flow diagram showing the adjustment procedure when the rolling method of the present invention is carried out in such rolling equipment. First, a target value of the plate temperature is set, in which the deformation resistance of the material to be rolled is small and heat scratches do not occur. The higher the target value, the higher the rolling efficiency, which is advantageous, but there is an upper limit because heat scratches occur.

Further, the minimum amount of roll coolant is set from the lubrication performance, the maximum amount is set from the installation capacity, and the strip coolant amount is set from the removal amount of deposits on the plate surface and the maximum amount is set from the installation capacity. , The plate temperature is detected and adjustment is performed according to the flow of FIG. Adjustments are made in the order of strip coolant amount, roll coolant amount, and rolling speed. As a specific example, a case where an austenitic stainless steel (SUS304) having a base plate thickness of 4.0 mm is rolled to 0.8 mm will be described. The board width is 1000 mm. Rolling was performed at a roll diameter of 90 mm and a rolling speed of 400 mpm (constant).

First, the plate temperature target value is set to 170
℃ was made. The roll coolant amount was set to 5000 to 9000 liters / min, and the strip coolant amount was set to 3000 to 6000 liters / min. First, as a comparative example, Table 2 shows the results of rolling with the roll coolant amount and the strip coolant amount fixed at the respective maximum amounts.

[0012]

[Table 2]

The plate temperature was in the range of 90 to 180 ° C., and the rolling load was 700 to 800 t. On the other hand, Table 3 shows the results of rolling with the same pass schedule and limiting the amount of coolant while detecting the sheet temperature according to the present invention.

[0014]

[Table 3]

Particularly, it was recognized that the sheet temperature increased after the 7th pass in the final stage, and the rolling load averaged approximately
It was reduced by 9%. Therefore, although the same pass schedule was used here for comparison, when the pass schedule was reviewed from this result, it was found that when the method of the present invention was used, rolling by eight passes was possible with one pass reduced.

[0016]

According to the present invention, as long as there is no problem in quality, the plate temperature is kept as high as possible for rolling, the rolling load is reduced, and the rolling reduction per pass can be set large, so that the number of passes can be reduced. It has the excellent effect of reducing the rolling efficiency. About 7-9% for SUS 304, SUS
Even in the case of 430, the rolling efficiency is improved by 3%.

Further, by controlling the plate temperature to a target value, the amount of thermal crown becomes constant and the surface shape of the steel strip becomes stable.

[Brief description of drawings]

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

FIG. 2 is a flow diagram showing an adjustment procedure in the embodiment of the present invention.

[Explanation of symbols]

 1 Tension reel 2 Deflector roll 3 Rolling machine 4 Strip coolant nozzle 5 Roll coolant nozzle 6 Thermometer S Steel strip

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B21B 37/00 BBP 37/46 45/02 320 8015-4E B21C 51/00 E

Claims (1)

[Claims] 1. In the cold rolling method for a metal strip, the temperature of the metal strip during rolling is detected, and the coolant flow rate or rolling speed is adjusted so that the temperature of this metal strip becomes as high as possible within a range not exceeding a target value. A method for cold rolling a metal strip, which comprises adjusting.