Claims:WE CLAIM:
1. An automated roll cooling arrangement for Rolling Mill comprising of:-
at least 2 nos. of Pressure manometer installed in each stand at both “Entry” and “Exit” point, indicating the delivery pressure of Roll Cooling water of that stand;
an electrical panel installed for the light indication to operators;
a PLC panel programmed for providing an output signal based on variance in input signal from threshold value;
wherein under condition that the delivery pressure of the coolant water of any of the said stands is below 4 bar, then an alarm and signal is provided for stop rolling.

2. The automated roll cooling arrangement as claimed in claim 1, wherein flow rate of coolant water is 610 m3 / hr at a maximum pressure of 7 bar.

3. The automated Roll Cooling arrangement as claimed in claim 1, wherein the light indicators are indicating the status of roll cooling headers in the form of green-red light signals.

4. The automated Roll Cooling arrangement as claimed in claim 1, wherein of automatic activating a hooter signal through PLC when there is abnormality in the Roll Cooling system

5. The automated Roll Cooling arrangement as claimed in claim 1, wherein system is capable of detecting variation of pressure due to reduction in flow rate on account of water contamination, non-functional booster pump, jamming of filters, abnormal behaviour of discharge valve, jamming of header nozzles, pipe leakage, and non-functional stand by pump.

Dated: this 26th day of March, 2018.
, Description:AUTOMATED ROLL COOLING ARRANGEMENT FOR ROLLING MILL

FIELD OF THE INVENTION:
The present invention relates to an automated roll cooling arrangement for rolling mill. More particularly, the present invention means for supplying a coolant to a work piece by ensuring the supply of uninterrupted and required pressure of roll cooling water during rolling in Finishing Mill.

BACKGROUND OF THE INVENTION
In rolling mills such as are used for production of high quality rolled flat metal strip, any variation in temperature over a work roll surface may cause differential radial expansion of the mill roll, and thus result in transverse variations in thickness and flatness including frequent blockage and breaking of the rolled product as shown in Fig. 6. Control of strip flatness (shape) requires maintenance of mill roll thermal camber within close tolerances.

Variations in the transverse thickness profile during rolling may cause non-uniform lengths to be produced at different locations across the strip width and these results in a non-uniform transverse stress distribution which may cause buckling. When rolling under tension, the buckling usually does not occur and a shape meter then measures the transverse stress variation which is interpreted as the tendency to subsequent buckling (or bad shape).

It is usual to provide at least one row of spray nozzles through which a coolant and/?r lubricant is applied to the roll surface. The flow rate of coolant through the pressure supplied to each zone of nozzles, or through each individual nozzle, is adjusted to control roll expansion and/or level of lubrication to suit the current rolling requirements. The latter' depend in a complex manner upon mill loads, roll deflections and ground profiles, work piece thickness and temperature profile and roll bending settings. It has been practiced to locate a shape meter downstream of the mill roll and to use feedback signals indicative of strip shape variation to control thermal camber in the roll. The shape meter is adapted to measure variations in the transverse stress and/or temperature distribution in the product resulting from rolling, including the effect of mill roll distortion.
Each spray nozzle may then be provided with a separate valve and the shape meter may be used for generating feedback signals to control individual valves. Individual valves are controlled to provide a greater flow rate of coolant to parts of the mill roll or work piece which are excessively hot or have more radial expansion than is desirable. In this way, variations in thermal distortion and consequent variations in strip shape may be minimized.

The only way available to ensure desired roll cooling has been physical observation by the Operator from a long distance. Our experience has been that due to various reasons such as lack of proper illumination, less water coming out of the stand, Operator not vigilant enough etc. resulted in roll breakage and stoppage of rolling.

Hot Strip Mill of Rourkela Steel Plant, as shown in Fig. 7, having a 1700mm semi-continuous mill comprising Walking Beam Furnaces of capacity 225 T / Hr, 3 Roughing Mills, i.e. one two high Reversing Mill (R0/ V0), one 4 high Reversing Mill (R1) and one 4 high Continuous Mill (R2¬), Coil Box, Six stand 4 high finishing Mill in tandem and two Hydraulic down coilers. It produces saleable hot rolled coils catering to external customers and as input material for internal customers for Cold Rolling Mill, Silicon Steel Mill and Pipe Plants.

Slabs, discharged from Reheating Furnaces are rolled in 3 Roughing Mills before entering 6 stands 4 high continuous mills where thickness of bar reduced (known as transfer bar) in each stand.

Each stand is 4 high with two work roll and two back up rolls. When the work roll comes in contact with the bar during rolling, it is very essential to cool the work Rolls (Top & Bottom). Hence, Roll cooling arrangement is provided in each stand with flow rate of 610 m3 / hr at 7 bar (upper threshold).

OBJECTIVE OF THE INVENTION:
It is therefore an object of the present invention is to include some automated indications and alarm in the form of automation needs to be provided in the Operator's Cabin so as to eliminate such unexpected eventualities.

A new cabinet with indication lamps designed for individual stands and installed in the Operator’s cabin for visual alertness. The “GREEN” light indicates proper roll cooling water pressure, where as “RED” light indicates inadequate / complete stoppage of water supply.

At least 2 nos. of Pressure manometer installed in each stand, both “Entry” and “Exit” point, indicating the delivery pressure of roll cooling water of that stand. If the delivery pressure of any of the six stands is below 4 bar, then a buzzer / alarm in the Speed Cabin signals the operator to stop rolling. Less than desired pressure or sudden stoppage of roll cooling water damages the quality of hot rolled strip and even roll life. An electrical panel installed for the “GREEN/RED” indication inside the Operator Cabin. In order to make the buzzer functional, it was incorporated with Finishing Mill ABB PLC system and also 90 seconds provided in order to clear off the bar from the Finishing Mill.

Therefore such as herein described there is provided 1. An automated roll cooling arrangement for rolling mill comprising of at least 2 nos. of Pressure manometer installed in each stand at both “Entry” and “Exit” point, indicating the delivery pressure of roll cooling water of that stand. An electrical panel installed for the light indication to operators, a PLC panel programmed for providing an output signal based on variance in input signal from threshold value; wherein under condition that the delivery pressure of the coolant water of any of the said stands is below 4 bar, then an alarm and signal is provided for stop rolling.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWING:
Fig.1 illustrates the installation of pressure manometer in accordance with the present invention;
Fig. 2(a) and (b) illustrates the pressure manometers used to connect a DC relay in accordance with the present invention;
Fig. 3 illustrates the Open and Close contacts of relay in accordance with the present invention;
Fig. 4 illustrates the colour indication system in accordance with the present invention;
Fig. 5(a), (b), (c) and (d) illustrate the different operations of the cooling arrangement in accordance with the present invention;
Fig. 6 illustrates the broken Finishing Mill Work as per the prior art;
Fig. 7 illustrates the six stand finishing mill complex of hot strip mill in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION:
Continuous flow of roll cooling water at desired pressure is of paramount importance for smooth operation of Finishing Mill of Hot Strip Mill. The On-off control of valves is herein used to reduce the complexity of communication interfaces between automation equipment and the valve actuators and to reduce valve costs, variable flow being achieved by use of multiple valves of different sizes in each zone and/or by varying the ratio of "on-time" to "off-time". Known systems for roll shape feedback control utilize a large number of electric or pneumatically controlled valves which must be operable in an extremely hostile environment and are consequently each of costly construction. The valve nozzles are susceptible to blockage and because one blocked valve nozzle could result in roll overheating, it is usual to have a redundant set of "stand-by" valves and to stop the line if a severe blockage occurs.

Therefore, continuous flow of roll cooling water with required pressure is necessary for smooth rolling in Finishing Mill. Sometimes flow rate reduces, or even stops due to water contamination, Booster pump not working, filter jam, closing of discharge valve, jamming of header nozzles, pipe leakage at delivery site, stand by pump not working and the like. This led to problems like uneven roll cooling causing poor strip quality, reduced roll life, fire cracks in rolls or even breakage of rolls. Hence minimum 4 bars pressure (lower threshold) of roll cooling water is highly essential to ensure smooth rolling in Finishing Mill.

This essential condition of continuous flow at desired pressure was being ensured by the visual observation of the Operator sitting in the cabin at a far away place in the shop floor. However, very often due to human error this was resulting in ignorance and consequent breakage of work roll and stoppage of production. This was causing huge loss of money due to production loss, rectification of breakdown and replacement of rolls.

To eliminate this unwanted and unexpected surprises, this invention of installing Two Pressure Manometer in each stand in ‘Entry’ and ‘Exit’ side indicating delivery pressure of roll cooling water and a buzzer/Alarm as audio support in the Speed Cabin to stop rolling when the water pressure falls below 4 bar. ‘Green and Red’ light indication installed in Operator’s Cabin for providing visual indication when the water pressure is below 4 bar requiring immediate attention and action by the Operator has greatly helped in eliminating the breakage of rolls, stoppage of rolling in Finishing Mill and/or production of low quality HR Coil. This has been of great benefit for the HSM collectives as well as the organisation.

As shown in Fig. 1, the installation of Pressure Manometer (PM1-PM12) in ‘Entry’ and ‘Exit’ side of every Finishing Mill stands indicate the cooling water pressure. The required cooling water pressure should be = 4 bars to ensure smooth rolling. Hence, all the Pressure Manometer have been set at 4 bars. All the 12 nos. of Pressure Manometers installed in ‘Entry’ and ‘Exit’ point of each of six stands. The Entry and Exit side Pressure Manometer (PM) contacts have been used to pick up a 24V DC relay (K1-K6) is shown in Fig. 2.

Further, by using the ‘NO’ and ‘NC’ (Normal Open and Normal Close) contacts of the 24V DC relay,’Red’ and ‘Green’indication light for each stand has been provided in the Operator’s Cabin.Green light indicates when the roll cooling water pressure is = 4 bar implying that everything is normal for smooth running of the Finishing mills. Red light indicates when the roll cooling water pressure ? 4 bar implying an alarming situation to stop rolling in Finishing Mill and needs immediate attention for restoring the cooling water pressure at 4 bar level is illustrated in Fig. 3.

The ‘Green and Red’ indication system as per Fig. 4 is provided in the Operator Cabin for alerting the Operator visually. Another ‘NO’ contact of 24V DC relay (K1-K6) for each stand has been used for input toABB PLC system and programmed shown in Fig. 5.Using all the inputs, an out put has been generated to pick up another 24V DC relay (K7) for operating the Buzzer/Hooter for alerting the operators. A Reset Push Button has been provided in Operator’s cabin to stop the buzzer.

Slabs, discharged from Reheating Furnaces are rolled in 3 Roughing Mills before entering 6 stands 4 high continuous Finishing Mills where thickness of bar reduced (known as transfer bar) in each stand. Each stand is 4 high with two work roll and two back up rolls. When the work roll comes in contact with the bar during rolling, it is very essential to cool the Work Rolls (Top & Bottom).
Hence, Roll Cooling Water arrangement is provided in each stand with flow rate of 610 m3 / hr at a maximum pressure of 7 bar. Continuous flow of roll cooling water with required pressure is essential to eliminate uneven roll cooling and roll breakage.

A cabinet having indication lamps for individual stands installed in the Operator’s cabin for visual alertness. The Green light indicates the roll cooling water pressure of that particular stand is OK, whereas Red light indicates inadequate / complete stoppage of water supply.

As shown in Fig. 2 nos. of Pressure Manometer are installed in each stand both in ‘Entry’ and ‘Exit’ side indicating the delivery pressure of roll cooling water of that stand. If the delivery pressure of any of the six stands is less than 4 bar, then a Buzzer / Alarm is provided in the Speed Cabin to stop rolling. Reduced / stoppage of roll cooling water leads to inferior HR Coil quality and reduced roll life. An electrical panel has been installed for the ‘GREEN/RED’ indication inside the Operator Cabin. In order to make the Buzzer functional, it was incorporated with Finishing Mill ABB PLC system and also 90 seconds have been provided in order to clear off the bar from the Finishing Mill. Therefore the arrangement is capable of detecting variation of pressure due to reduction inflow rate on account of water contamination, non-functional booster pump, jamming of filters, abnormal behaviour of discharge valve, jamming of header nozzles, pipe leakage, and non-functional stand by pump.
Inventive step
? Elimination of the down time of the Finishing Mill with no roll breakage since the time of implementation of the invention

? Quality of HR Coil ensured due to elimination of uneven Roll Cooling.

? Material loss due to cobble in Finishing Mill, Roll breakage etc. Could be eliminated and unnecessary waste of money/resources of the organisation saved.

? Removal of broken roll from the stand in very unsafe and hazardous condition has been completely avoided.

? A safe and healthy working condition with almost no chance of human error ensured. This has heightened employee morale and motivation
INDUSTRIAL APPLICABILITY:
This unique invention will be of immense help to heavy and large industries including other manufacturing industries where water cooling of hot machinery and equipment with desired water pressure is required in operation to maintain the health and safety of the equipment and machinery.

Although the foregoing description of the present invention has been shown and described with reference to particular embodiments and applications thereof, it has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. It will be apparent to those having ordinary skill in the art that a number of changes, modifications, variations, or alterations to the invention as described herein may be made, none of which depart from the spirit or scope of the present invention. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such changes, modifications, variations, and alterations should therefore be seen as being within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

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