JPS58128208A - Method and device for supplying of cooling water for roll of cold rolling mill - Google Patents

Abstract

PURPOSE:To make the correction of the abrupt change in thermal crowns near the end part of band steel possible by supplying cooling water or low temp. to the central parts of rolling rolls and supplying cooling water of high temp. to both end parts thereof. CONSTITUTION:Many cooling water nozzles 3, 3-1 are mounted to a coolant header 1, and the inside of the header 1 are divided to three chambers by means of partition walls 8, 8-1. The cooling water L of low temp. which is controlled of pressure with a valve 5 is supplied through a piping 4 into the central chamber, and the cooling water H of high temp. which is controlled of pressure with valves 5-1, 5-2 is supplied through pipings 4-1, 4-2 into the chambers on both sides. The thermal crowns of work rolls are controlled to desired values by adjusting the openings of the valves 5, 5-1, 5-2, the positions of the walls 8, 8-1 and the cooling water L, H.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for supplying roll cooling water to a cold rolling mill.

The requirements for the shape of 6-way rolled products have become increasingly strict in recent years, and in order to increase the shape control ability of cold rolling mills, we have developed a 6Hi mill with a roll axial movement adjustment mechanism and a 2-way operating roll chock. A split double chock bender, etc., has been used with some success, but modern cold rolling mills with a maximum rolling speed of 2000 m/min or more require a 6Hi mill with excellent shape control ability. Even when used, it is often difficult to roll a perfectly flat plate. That is,
If we carefully examine the shape of the copper strip that has been rolled at high speed using the conventional method, we will see that the area a little further in from both ends of the Steel Hotaru 19 has so-called quarters, which are elongated and wavy, as shown in Figure 1. It often has a buckle of 20. L is the width of the board.

As a result of detailed research and analysis on this matter, we found that the thermal crown of the roll becomes large during high-speed rolling, and when we examine the diameter distribution of the roll in the axial direction due to this thermal crown, it becomes a parabola that is easy to correct by roll bending, etc. The diameter distribution does not form a typical distribution, but the diameter distribution changes rapidly near the boundary between the rolled part in contact with the copper strip and the part not in contact with the copper strip, that is, near the end of the copper strip, as shown in curve A in Figure 2. It has become clear that it has become. Curve B is an example of a roll crown obtained by roll bending, but even if you try to equalize the rolling load in the width direction to improve the shape of the rolled steel strip, the roll crown can only be modified parabolically. To.

It is not possible to correct the roll thermal crown by adjusting the pending force. In the figure, C indicates the roll center and D indicates the width edge of the board.

Therefore, in the area indicated by the hatch in Figure 2, the gap between the upper and lower rolls is relatively small, and this area is rolled down more strongly than other areas, and as a result, the area that is drawn inward from the edge of the board is a little smaller. This will cause extra stretch in the area and cause a quarterback.

Quarter buckles occur due to these reasons, but because the shape of the thermal crown changes significantly, with the center elongating and the edges elongating, conventionally, in order to stabilize the shape, the cooling water flow rate has been adjusted. Although a method of rolling steel sheets has been implemented in some rolling mills, it has not yet been possible to freely control the shape of the thermal cracker run in the roll axis direction.

The present invention makes it possible to correct the rapid thermal crown change near the end of the copper strip that characteristically appears in the roll thermal crown during rolling. Focusing on the temperature, the gist is that cold rolling is characterized by supplying low-temperature cooling water to the center of the roll and supplying high-temperature cooling water to both ends of the roll. A roll cooling water supply method for a rolling machine, and a partition wall is provided in a coolant header provided parallel to the rolling roll axis, and cooling water supply systems with different temperatures are provided in chambers in the coolant header provided across the partition wall. This is a roll cooling water supply device for a cold rolling mill.

Next, the present invention will be explained in detail using drawings.

In Fig. 3, 1 is the width of the rolled material, 2 is the rolling roll, and the coolant rudder l has many cooling water nozzles 3.3.
-1 is attached, and to the coolant = 4- The interior of the ladder L is divided into three chambers by partition walls B and B-t.
This septum is preferably located on the roll thermal crown at ±200 mm from the copper strip width edge.

Low temperature cooling water whose pressure is controlled by valves 5 is supplied from piping 4 to the central chamber, and valves 5-1. ．． 5-2 pressure controlled high temperature (3 to 30℃ higher than low temperature cooling water)
Cooling water H (high) is being supplied.

That is, valve 5. 5-1.5-2 opening adjustment and bulkhead 8. 8
The work roll thermal crown is controlled to a desired value by adjusting the position of -1 and adjusting the cooling water and H.

In this way, cooling water with different temperatures is supplied to the center and both ends of the rolling roll, and the partition wall inside the coolant tube mentioned above is positioned slightly inside the both ends of the steel strip. Specifically, 200 mm from both ends of the copper strip.
The position is around am.

Also, the position of this partition wall can be determined by the width of the copper strip. Specifically, referring to FIG. 4, the partition wall 8.8-1 can be slid within the coolant header 1, and its position within the header can be changed from the outside by means of a rod 9.9-1. 12.1
2-1 is a motor, and the rotation of this motor drives the pinion 11.11-1, and the rod 9.11-1 is driven. 9-. 1
Rack cut into 10. 10-1 is driven to change the position of the partition wall 8.8-1.

The position of this bulkhead 8.8-1 is the motor 12, 12-1.
Cersin 13 linked to 13-1. Therefore, it becomes possible to supply cooling water a, b, and c having different temperatures and pressures to each chamber in the header 2.

The valve 5.5-1 for adjusting the opening degree may be provided between the coolant header 1 and the cooling water nozzle 3.3-1 as shown in FIG. 7, and there is no particular limitation.

Next, a method for supplying high-temperature cooling water or low-temperature cooling water will be explained with reference to FIGS. 5 and 6.

The cooling water injected by the coolant headers 1 and 1' is
Results of cooling the rolling roll 2 and rolling plate 6.

The temperature is raised by 3 to 30°C, and the waste is collected in the pit 7, and then passed through the pipe 46- and collected in the recovery tank 14. The recovered cooling water a stays in the recovery tank 14 for a certain period of time, and the oil content is floated and separated, so the heated cooling water with reduced oil content is taken out from the outlet of the recovery tank 14, passed through the filter 15, and pumped into the pump 16. The pressure is increased and the water passes through the pipe M-17 and is used as high temperature cooling water H to cool both sides of the rolling roll.

On the other hand, a low-temperature cooling water tank such as industrial water passes through a pump 16-1 and a pipe 17-1 and is used as a low-temperature cooling water tank to cool the center of the roll. Figure 6 is similar to Figure 5, but in order to obtain low-temperature cooling water, one recovery tank 14
The cooling water is passed through the pipe 17, cooled to an appropriate temperature by the cooler 18, and then passed through the pipe 17-1 to be used as low-temperature cooling water. Either method may be used, and there is no particular limitation.

Although not shown in FIGS. 5 and 6, in order to ensure the roll thermal crown control by the runt control according to the present invention, there is a thermometer and a device for adjusting the temperature of high-temperature water. Depending on the rolling conditions of the rolling mill, the temperature may be raised using a mixing device for high-temperature water and low-temperature water or, if it is necessary to further raise the temperature of high-temperature water, a heat exchanger or the like. Various improvements may be made without departing from the spirit of the invention.

Next, we will discuss the formation mechanism of roll thermal crown, which occurs as a result of the rise in roll temperature due to processing heat generated during rolling and the roll cooling effect of roll cooling water.

The amount of heat input QH to the rolls in the plate rolling section can be expressed by equation (1). QH=hH(θ8-〇r) ・・・・・・
...(1) Also, the amount of heat output from the roll due to the roll cooling water Q.

can be expressed by equation (2). Qc=hc(θ, -e=)--
-(2) hH: Heat transfer coefficient between roll and plate, θS:
plate temperature, θr: roll temperature, hc: roll-to-cooling water heat transfer coefficient, θW: cooling water temperature.

From equations (1) and (2), the amount of heat input and heat output from the roll is -
It is clear that it is proportional to the temperature difference between the rolls and the temperature difference between the rolls and the cooling water, but in the plate rolling section near the center in the roll axis direction, θS is the plate temperature during rolling, and is generally 80 to 250. 8-°C, whereas in the area outside the plate, θB is the atmospheric or cooling water temperature, which is generally below 60°C, so the thermal conditions of the roll are lower in the roll axis direction. Because of the large difference in the roll temperature, the roll temperature, which is determined as a result of the balance between heat input and heat output, changes in the roll axis direction, and the result of the difference in thermal expansion due to temperature distribution takes the form of a thermal crown, as shown in curve A in Figure 2. be. The present invention improves the axial temperature distribution of the roll by changing the 0wt roll axial direction in equation (2).

As described above, according to the present invention, by supplying low-temperature cooling water to the center of the rolling roll and supplying high-temperature cooling water to both ends, the plate edges that are characteristically rough during cold rolling can be It is possible to correct sudden thermal crown changes in the vicinity, which is extremely useful.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a quarter buckle (defective shape), Fig. 2 is an explanatory diagram of the diameter distribution of a rolling roll during rolling, and Figs. 3 to 7 are explanatory diagrams showing the cooling water supply mode of the present invention. 1°°・Coolant header 2...Pressure [0-le 6・
・Rolled plate 8...Partition wall 12...Motor l〇- Rod/Kuni 3rd stage 2 figure Rolling 9 sides) Elbow (Hirom) Broom 4 figure

Claims (1)

[Claims] 1. Roll cooling water supply for a cold rolling mill, characterized in that low-temperature cooling water is supplied to the center of the roll, and high-temperature cooling water is supplied to both ends of the roll. Method. 2. Rolls of a cold rolling mill in which a partition wall is provided in a coolant header installed parallel to the rolling roll axis, and cooling water supply systems with different temperatures are provided in chambers in the runt header, separated by the partition wall. Cooling water supply device.