Pre-cooling system having controlled internal adjustment

Abstract

The invention relates to equipment for cooling a metal strip (2) having a liquid coating to be solidified, wherein said strip is continuously moving. Said equipment is characterized in that each half-cooler (11, 12) is divided, over the length thereof, into at least two sections, a first section (13) and a second section (14), in the direction of the movement of the strip (2). The first section (13) is separated from the second section (14) in each half-cooler (11, 12) by a respective internal adjustment device (7, 8), making it possible to change the gas flow/pressure parameter so that the value of said gas flow/pressure parameter is different in the first section (13) from the value of said parameter in the second section (14).

Claims

1. Equipment for cooling a metal strip (2) having a liquid coating to be solidified, said metal strip being continuously moving, said equipment including a cooling box (1) provided with two gas half-coolers (11, 12), preferably using air, each designed to cool one face of the strip (2) and having each, on its inner face across from the respective face of the strip, a plurality of nozzles or slots (15) for injecting the gas at a certain flow rate, each half-cooler (11, 12) being divided over its length into at least two sections, a first section (13) and a second section (14), successively arranged in the direction of the movement of the strip (2), the first section (13) being separated from the second section (14) in each half-cooler (11, 12), transversally relative to the movement of the strip, by an internal regulating device (7, 8) able to modify the flow rate/pressure parameter in the first and second respective segments, the equipment being characterized in that the internal regulating devices (7, 8): either are diffusers comprising two superimposed plates each having a plurality of holes or slots and whereof the movement of one relative to the other results in modifying the opening section of the diffusers; or comprise a single rotary flap or a plurality of rotary flaps; or comprise an adjustable moving plate of the guillotine type, the half-coolers (11, 12) being connected to a shared supply circuit (3), supplied with gas by as single fan (4).

2. The equipment according to claim 1, characterized in that the internal regulating devices (7, 8) are actuated by pneumatic or electromechanical actuators (9, 10).

3. The equipment according to claim 2, characterized in that the actuators (9, 10) of the internal regulating devices (7, 8) are remotely controlled by a line operator.

4. The equipment according to claim 1, characterized in that the fan (4), is in turn, actuated by a motor (5).

5. The equipment according to claim 4, characterized in that the supply circuit (3) shared by the two half-coolers (11, 12) is connected to the second section (14) of at least one of the two half-coolers (11, 12) or to the section with a higher flow rate or higher pressure of gas.

6. The equipment according to claim 4, characterized in that the motor (5) is provided with a speed variator (6) making it possible to regulate the cooling gas flow rate/pressure parameter.

7. The equipment according to claim 6, characterized in that it comprises means for jointly or individually actuating the internal regulating devices (7, 8) as a function of the gas flow rate/pressure parameter regulated by the speed variator (6) and the desired coating quality.

8. The equipment according to claim 1, characterized in that the internal regulating devices (7, 8) are duplicated, thereby creating a third section, intermediate between the first inlet section of the strip and the second outlet section of the strip, in order to obtain different gas blowing speeds in the aforementioned three sections.

9. The equipment according to claim 1, characterized in that it is provided to move the strip in a vertical strand.

10. The equipment according to claim 1, characterized in that it includes a pyrometer installed after the internal regulating devices (7, 8) in the direction of the movement of the strip, to monitor the solidification of the coating.

11. A method for cooling a metal strip (2) moving continuously and having a liquid coating to be solidified, using the equipment according to claim 1, comprising a step for modifying the flow rate/pressure parameter of gas injected by means of internal regulating devices (7, 8) such that the value of said injected gas flow rate/pressure parameter is different in the first section (13) relative to its value in the second section (14).

12. The method according to claim 11, characterized in that the injected gas flow rate/pressure parameter is modified such that the value of said injected gas flow rate/pressure parameter is lower in the first section (13) compared to its value in the second section (14).

13. The method according to claim 11, characterized in that the gas flow rate injected in the first section of the cooling equipment, called primary flow rate, is regulated to control the solidifying front and solidification speed of the coating still in liquid phase at the inlet of the first section.

14. The method according to claim 11, characterized in that the injected gas flow rate in the second section of the cooling equipment, called secondary flow rate, is regulated to be higher than the primary flow rate and compatible with predetermined cooling slopes.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 diagrammatically shows a cooler according to the state of the art.

(2) FIG. 2 diagrammatically shows a cooler according to the present invention, equipped with adjustable internal flow rate equipment remotely controlled.

(3) FIG. 3 shows a first embodiment of the regulating system according to the invention, in the form of a diffuser.

(4) FIG. 4 shows a second embodiment of the regulating system according to the invention, in the form of a flap.

(5) FIG. 5 shows a half cooler having a third section.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

(6) The present invention provides a solution to the technical problem set out above (see FIG. 2). According to the invention, internal regulating systems or equipment 7, 8 are respectively installed in the two air half-coolers 11, 12. These regulating systems 7, 8 are intended to modify and adjust the cooling fluid flow rate between the lower parts (inlet of the cooler) and the upper parts (middle and outlet of the cooler) while maintaining a uniform flow rate per unit of surface for each section. The care taken in producing the equipment to avoid disrupting the flow of the gas is very important in order to have homogenous and regular cooling of the coating to be solidified.

(7) According to one particular embodiment, these separating systems 7, 8 may be duplicated if necessary in order to obtain different blowing speeds between the inlet, the middle and the outlet of the cooler, respectively.

(8) These regulating systems 7, 8 are advantageously actuated by pneumatic or electromechanical actuators 9, 10, with the possibility of being remotely controlled by the line operator. These regulating systems 7, 8 are preferably actuated jointly as a function of the air flow rate regulated by the variator 6 of the motor 5 of the fan 4 and the obtained coating quality.

(9) According to preferred embodiments, these regulating systems 7, 8 can include:

(10) diffusers 7A, 8A comprising two superimposed plates, both having a series of holes or slots. The movement of one of the plates relative to the other results in decreasing the opening section and therefore acts as a homogenous adjustable diffuser with respect to the cooling air (see FIG. 3), a single rotary flap or a series of small rotary flaps (see FIG. 4), a single adjustable moving plate 7B, 8B of the guillotine type (not shown), etc

Advantages of the Device

(11) The system according to the present invention offers the following advantages.

(12) The gas flow rate in the first part or section of the cooler, called primary flow rate, can be regulated in order to monitor the solidifying front and solidification speed of the coating still in liquid phase at the inlet of the cooler, and therefore to obtain the best possible coating quality.

(13) The internal regulating systems or equipment for the primary flow rate can be remotely controlled by the operator depending on a cooling quality/slope criterion. The primary blowing speed therefore continues to be monitored compared to a completely manual system. A pyrometer 17 or any other temperature measuring system, adapted to a moving strip, can be installed just after the regulating systems in order to monitor the cooling slope.

(14) The second parts or sections of the two half-coolers 11, 12 can then have a secondary cooling flow rate that is significantly more substantial and compatible with the necessary cooling slopes, or with an increase in the cooling capacity of the cooler as a whole.

(15) The cooling of the two half-coolers 11, 12 will therefore be adjusted and balanced between the speed variator 6 and the regulating systems 7, 8 delimiting the cooling inlet section. This gives the cooler a very considerable flexibility.

(16) The regulating systems 7, 8 also allow optimal adjustment of the coating quality between the two faces of the strip 2, given that they will need to have the option of being controlled individually if necessary.

(17) Due to the design of the system for monitoring the cooling of the two parts, the flow rate of the cooling fluid by surface unit is uniform in each of the sections, and in particular transversely.

(18) Another advantage is the flexibility of the system: it will be very easy to move the regulating system to another position in the (pre-)cooler if the starting position is not or ceases to be appropriate. It is for example possible to provide three different positions of the regulating system.

LIST OF REFERENCES

(19) 1. Cooling box 2. Metal strip 3. Gas supply circuit 4. Fan 5. Motor 6. Motor speed variator 7. Internal regulating device 7A. Diffuser 7B. Adjustable moving plate 8. Internal regulating device 8A. Diffuser 8B. Adjustable moving plate 9. Actuator 10. Actuator 11. Half-cooler 12. Half-cooler 13. First section of the cooler 14. Second section of the cooler 15. Gas injection nozzles or slots 16. Third section of the cooler 17. Pyrometer