Cooling section comprising power cooling and laminar cooling

Abstract

A cooling section for flat rolling stock has a working region, through which the flat rolling stock is guided. The working region can be supplied with a liquid coolant by means of a number of spray beams. The liquid coolant is fed from a reservoir for the liquid coolant to the spray beams by means of a pump and a supply system. Valves are arranged upstream of the spray beams in the supply system. Opening positions of the valves are set by a control unit of the cooling section according to a respective sub-flow that is to be applied to the flat rolling stock by means of each spray beam. Also, the delivery rate of the pump and/or a line pressure generated by the pump in the supply system are set by the control unit according to the total flow that is to be applied to the flat rolling stock by means of all the spray beams.

Claims

1. A method for cooling a rolling stock with a liquid coolant, comprising: guiding the rolling stock through a working region comprised of a plurality of spray beams oriented and configured to spray the liquid coolant on the rolling stock being guided through the working region; pumping the liquid coolant to the spray beams from a reservoir via a pump and a supply line system to the spray beams; using a control unit to set opening positions (si) of valves which are arranged upstream of the spray beams and within the supply line system according to a respective partial flow (fi) through the valves to be applied to the rolling stock by means of each respective spray beam; and using the control unit to reduce a delivery power of the pump and/or reduce a line pressure (p) generated by the pump in the supply line system upstream of the valves according to a total flow (F) of the liquid coolant to be applied to the rolling stock by spray from all of the spray beams together by summing all of the partial flows (fi) through the valves arranged upstream of each of the respective spray beams, wherein the control unit further sets the opening positions of the valves arranged upstream of the spray beams to be relatively open wide and reduces the delivery power of the pump and/or the line pressure generated by the pump to avoid cavitation of the liquid coolant in each valve at the set open position of each valve.

2. The method as claimed in claim 1, wherein the rolling stock is a flat rolling stock having flat surfaces on which the spray beams spray coolant.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a side view of a cooling section,

(2) FIG. 2 shows characteristic curves and

(3) FIG. 3 shows a valve in section.

DESCRIPTION OF AN EMBODIMENT

(4) As shown in FIG. 1, a cooling section for a flat rolling stock 1 has a working region 2 through which the flat rolling stock 1 is guided. A number of spray beams 3i (i=1, 2, 3, . . . ) are arranged in the working region 2. The working region 2 can be supplied, by means of the spray beams 3i, with a liquid coolant 4. The liquid coolant 4 is fed to the spray beams 3i from a reservoir 7 for the liquid coolant 4 via a pump 5 and a supply line system 6. The spray beams 3i are generally, as shown in the representation of FIG. 1, arranged both above and below a pass line 8, such that the spray beams 3i can apply the liquid coolant 4 to the flat rolling stock 1 both from above and from below the opposite surfaces of the flat stock. In some cases, however, it can be sufficient for the spray beams 3i to be arranged only above the pass line 8.

(5) Within the supply line system 6, valves 9i are arranged upstream of the spray beams 3i. The valves 9i or, more specifically, their opening settings si, can be set by a control device 10. The valves 9i are controlled by the control device 10 such that the opening settings si of the valves 9i are set in accordance with a respective partial flow fi, which is to be applied to the flat rolling stock 1 by means of the respective spray beam 3i. Furthermore, the control device sets a delivery power M of the pump 5 in accordance with a total flow F which is to be applied to the flat rolling stock 1 by means of all of the spray beams 3i together. As an alternative to the delivery power M, the pump 5 can be controlled in a manner corresponding to the total flow F so as to set a line pressure p which is generated in the supply line system 6 by means of the pump 5. The total flow F can be determined by the control device 10, automatically and directly by summing the partial flows fi.

(6) The control device 10 generally takes the form of a software-programmable control device. This is indicated in FIG. 1 by the fact that the abbreviation μP, for microprocessor, is shown in the control device 10. In this case, the control device 10 is programmed with a computer program 11. The computer program 11 comprises machine code 12 which can be directly executed by the control device 10. In this case, the execution of the machine code 12 by the control device 10 effects the corresponding formation and mode of operation of the control device 10.

(7) The control device 10 accordingly controls the pump 5 such that the line pressure p in the supply line system 6 can be set between a minimum value pmin and a maximum value pmax. Furthermore, the control device 10 accordingly controls the valves 9i such that their opening settings si can be set between a respective fully closed position si0 and a respective fully open position si1. It is possible, as shown in FIG. 2, for the opening positions si to be set in a step-free manner. Alternatively, setting could be effected in multiple steps. A respective partial flow fi corresponds to every opening position si of the valves 9i. In addition, the partial flow fi is also, as shown in FIG. 2, dependent on the line pressure p.

(8) In the event that the line pressure p is at the maximum value pmax, there exists, as shown in FIG. 2, at least one respective opening position si of the valves 9i at which the liquid coolant 4 flowing through the respective valve 9i cavitates, i.e. bubbles form in the liquid coolant 4 flowing through the respective valve 9i, downstream of the respective valve 9i as seen in the direction of flow.

(9) This effect, which is per se disadvantageous and undesired, can be readily accepted within the context of the present invention because, within the context of the present invention, in order to obtain a certain partial flow fi, it is possible to vary not only the opening position si of the corresponding valve 9i, but also the delivery quantity M of the pump 5 and/or the line pressure which the pump 5 generates in the supply line system 6.

(10) The following statements relate to the case in which the line pressure p is at the maximum pressure pmax. As shown in FIG. 2, the liquid coolant 4 flowing through the respective valve 9i has, at the respective fully open position si1, a respective maximum flow fi1. At that respective opening position si at which the liquid coolant 4 flowing through the respective valve 9i cavitates, the liquid coolant has a lower partial flow fiK, hereinafter termed cavitation flow fiK. The ratio of the respective maximum flow fi1 to the respective cavitation flow fiK is generally at most 5:1. It can also be lower, for example 3:1 or 2:1.

(11) By virtue of the fact that it is possible to avoid cavitation by accordingly reducing the delivery power M and/or accordingly reducing the line pressure p, it is clearly possible for the valves 9i to be formed as butterfly valves, as shown in FIG. 3.

(12) The present invention has many advantages. In particular, cavitation can easily be avoided during operation as laminar cooling. Furthermore, it is clearly possible to retro-fit existing power cooling installations. All that is necessary is for the control device 10 to be exchanged or reprogrammed and for the pump 5 to be appropriately capable.

(13) Although the invention was described and illustrated in more detail using the preferred exemplary embodiment, the invention is not restricted by the disclosed examples and other variations can be derived herefrom by a person skilled in the art without departing from the scope of protection of the invention.

LIST OF REFERENCE SIGNS

(14) 1 Flat rolling stock

(15) 2 Working region

(16) 3i Spray beam

(17) 4 Coolant

(18) 5 Pump

(19) 6 Supply line system

(20) 7 Reservoir

(21) 8 Pass line

(22) 9i Valves

(23) 10 Control device

(24) 11 Computer program

(25) 12 Machine code

(26) F Total flow

(27) fi Partial flows

(28) fiK Cavitation flow

(29) fi1 Maximum flow

(30) M Delivery power

(31) p Line pressure

(32) pmin Minimum value

(33) pmax Maximum value

(34) si Opening positions

(35) si0 Fully closed positions

(36) si1 Fully open positions