TECHNICAL FIELD OF THE INVENTION
The system of present invention facilitates improved control for Hot Saws of Rail and Structural Mill, and networking of the control processing units for centralized monitoring, and a common mill mimic for fault diagnosis. The integrated system, thereof, ultimately controls a group of seven saws and other associated equipments of Rail Mill. This new improved system has immensely benefited the steel plant by increasing productivity with reduction in downtime of cutting saws. The faster fault analysis has increased saws availability.
BACKGROUND OF THE INVENTION
The Rail and Structural Mill is divided into four major areas namely Reheating furnaces, Mill Area, Hot Saw Zone and Cooling Beds. The input material to the rolling stands of Rail Mill is bloom of 4 T weight in primarily two grades R-52 i.e. 52 Kg per meter and R-60 i.e. 60 Kg per meter. The bloom is rolled into Rails through Roughing, Intermediate and Finishing Stand. The product obtained after finishing stand is cut into pieces using hot saws depending upon the requirement (Fig 1: Process mimic). There are in all seven saws, placed at a separation of 13.5 meters from each other in a row. The cutting operation, executed in two strokes, involves precise positioning of full rail in the roller table, selection and initiating saw operation, removal of crop and sample pieces and dispatch of material for further processing at Rail Finishing area. The product range of rails includes 13m, 26m and long

rails. Normally an extra length (minimum 0.5 meters) per piece is cut, over and above the required product length of 13m, 26m & long rails to enable final finishing in the finishing area. In addition, the cutting also involves a head and tail end cutting for proper end shapes. Sample pieces are also cut at regular time interval for quality testing. The number of rail pieces available per bloom depends upon several factors, the grade of rail being a major one. For the product grade R-52, the bloom can be cut into 6 pieces of 13.5 m each as hot saw product for sending it to final finishing where it is end finished for 13 meters. In case of grade R-60, the number of pieces obtained per bloom at hot saws is five. For cutting into 26 meter length, alternate saws are selected.
Average time available to clear one full length of rail is less than two minutes. The time gap between two full length rails being so less, any breakdown or delay immediately results into cobbles of all the blooms in the rolling zone.
The cutting sequence in short can be described as follows. The rail coming out of finishing stand is brought to the furthermost saw by four roll table segments. The rail is positioned properly and then saws to be operated are selected for first CUT. The selected saws having continuously rotating discs are brought forward to cut the rail and after CUT, the saws are retracted to its home position based on a forward limit switch. Now the relevant pushers are operated to push out the scrap pieces from roll table and then roll table is moved once again to cut the balance length of the rail (second cut). The sequence of

positioning on roll table, saw selection, CUT and pusher operation is repeated.
US5142955 discloses an apparatus which receives lumber pieces from a scanner, calculates, and cuts end defects based on information received from scanner about contour plot of the lumber piece. Risks of control system failure are more and the result of failure can be very unsafe in case of steel mill operation.
US6681672 teaches material speed control based on alignment using laser. However, cutting of material in stationary condition by multiple saws was not known from this prior art.
US7032486 discloses mill saw with a saw frame driven by a slider-crank drive, whose parallel saw blades, which cut only in one direction, are cantilevered, and with a feed conveyor for the stock to be cut, which is driven intermittently during the cutting stroke of the saw frame as a function of the cutting speed by means of at least one motor separated from slider crank drive and connected to a controlling system.
The existing control system for the hot saws was conventional and in operation since inception of the mill. The major limitations are detailed below.
• The control interlocking among devices such as Roll Table, Hot Saw main drives, Saw travel, Saw position and pusher operation were realized through control relays. The control relays being electro-mechanical devices have limitations in terms of reliability and longevity. Also,

any change is difficult to realize due to hardwiring required.
• The control desks in the operator pulpit were hardwired to electrical control panel ECR (across the transportation roll table). With so many process mechanisms to control, huge numbers of multicore signal cables were running for long distances at 200VDC level. As installation gets older, these cables start failing and replacement is required involving time and cost.
• The operator pulpit had 5 control desks with a number of control elements staggered due to various phases of commissioning and modifications carried out thereafter causing inconvenience to operator. The control elements had multiple contacts associated with each position for usage in various logic circuits. Any malfunction of contact used to cause lot of delay in diagnosis.
The operator had no feedback on commands as provided. Also, for this reason, the problem diagnosis used to take longer sometimes leading to cobble.
Thus there is a need to provide a standalone control system for all the saws in a single controller.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a standalone control system for all the saws in a single controller, which overcomes the drawbacks of prior art.

Another object of the present invention is to provide mimic panel annunciation of status of critical process to overcome the drawbacks of prior art, which does not have any such facility to check operational healthiness/ malfunctioning.
Another object of the present invention is to provide interconnectivity of hot saw motors and other auxiliaries in common processor unit.
Another object of the present invention is to provide newly designed set of control desks for proper feedback and convenience to the operators.
Yet another object of the present invention is to provide schemes for energy saving and enhancement of safety.
SUMMARY OF THE INVENTION
Thus according to one aspect of the present invention there
is provided an improved control and monitoring system for
operation of multiple hot saws and associated auxiliaries
in steel mill, said system comprising :
controller desk means being designed with plurality of
switch means in a manner to operate in several operational
modes;
controller means;
relay means being operatively interfaced with said
controller means;

input/output unit remotely located in a manner to receive input and output signals from said controller desk means wherein said controller means being fed with various types of cut scheme adapted to select saw means in one or in plurality at a time so as to obtain desire cut.
The other objects and advantages of the present invention will be apparent from the description provided hereinbelow with reference to the accompanying figures and detailed description provided herein below.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 illustrates the process mimic depicting Rail Mill Process Flow
Figure 2 illustrates the control scheme
Figure 3 illustrates new control desks
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Keeping above limitations in view, a new control scheme based on PLC was designed and introduced (Fig 2: Control Scheme) . This system has PLC (1) in Electrical Control Room (ECR) (2) and one remote I/O (RIO) unit (3) near control desks (4) inside operator pulpit (5) . All the input and output signals of control desks are collected on RIO unit (3) and sent to PLC (1) over cold redundant communication BUS thereby drastically reducing use of control cables. The PLC I/Os (6) are interfaced to field signals (Table:1) through control relays. All the five number of control

desks were redesigned after taking into account the operator's experience. The control desk includes saw select (7), pushers (8), RT (9), feed and master controllers (10). The functionalities of individual control element were scrutinized and total number of control elements was reduced and built into four desks (Fig 3: New Control desks). New control desks were designed with pushbuttons, multiple position stay-put selection switches and auto reset type master controllers. Several operation modes such as Manual, Semi-Auto, Auto etc. were introduced for most frequently used combinations. Selection for cut schemes have been incorporated based on various operational practices. For example, 4+3 cut scheme means, a scheme of operation where five saws are selected in first stroke making 4 pieces and four saws in second stroke making 3 pieces. All such schemes are now implemented by operating a single selection switch, enabling a considerable decrease in number of control elements required to be operated per cut of Rail. The desks have LED lamps to assist operator through display of feedback on selections made and commands given. A Mimic of Hot Saw area has also been provided in operator pulpit for instantaneous indication of tripping or forbiddance.



The structure thus conceived is adaptable to numerous modifications or variations. In practice the materials and dimensions may be dependant upon specific requirements and that will be comprised within its true spirit.

WE CLAIM
1. An improved control and monitoring system for
operation of multiple hot saws and associated
auxiliaries in steel mill, said system comprising :
controller desk means being designed with plurality of
switch means in a manner to operate in several
operational modes;
controller means;
relay means being operatively interfaced with said
controller means;
input/output unit remotely located in a manner to
receive input and output signals from said controller
desk means
wherein said controller means being fed with various
types of cut scheme adapted to select saw means in one
or in plurality at a time so as to obtain desire cut.
2. System as claimed in claim 1 wherein said switch means selectively comprises push buttons, multiple position stay-put selection switches, auto reset type master controller and combination thereof.
3. System as claimed in claim 1 said operational modes are selectively manual, semi-auto and automatic and combination thereof.
4. System as claimed in claim 1 wherein said controller means is a programming logic controller.

5. System as claimed in claim 1 wherein said signals selectively comprise forward, reverse and trip signals for operating all roll table.
6. System as claimed in claim 1 wherein said signals further comprise START, STOP and BREAK signals for operating main drive.
7. System as claimed in claim 1 wherein said signals further comprise Forward, Reverse, Stop, Forward limit, Reverse limit, extreme limits and Trip signals for operation of feed mechanism.
8. System as claimed in claim 1 wherein said signals further comprise Forward, Reverse, Stop and Trip for operations of pushers.
9. System as claimed in any preceding claims further comprises mimic panel annunciating means adapted for instantaneous indication of tripping or forbiddance and other critical operational status.
10. An improved control and monitoring system for operation of multiple hot saws and associated auxiliaries in steel mill as herein substantially described and illustrated with reference to the accompanying figures.

The present invention relates to an improved control and monitoring system for operation of multiple hot saws and associated auxiliaries in steel mill. The system comprises controller desk means (4) being designed with plurality of switch means, operational modes, controller means, relay means operatively interfaced with said controller means, input/output unit (3, 6) receiving input and output signals from the controller desk means. The controller means is fed with various types of cut scheme adapted to select saw means in one or in plurality at a time so as to obtain desire cut.