Title of Invention

" CONTROL SYSTEM FOR COILER JAW ADJUSTMENT IN SKELP MILL"

Abstract The control system for coiler jaw positioning operation for skelp mill operable for remote location avoiding manual reliance and unsafe and hazardous condition comprising coiler drum (CD) operatively connected to a motor (CM) and having atleast four jaws; means for feeding the skelp end to the coiler jaw for coiling of the skelp thereon said coiler drum (CD); control means comprising means for varying the speed of the motor rotating said coiler drum ; means for sensing the position of said coiler drum jaw with respect to said skelp end and feeding said skelp end into said jaw when both are in alignment for coiling of said skelp on said coiler drum. It is thus possible by way of the system of the invention to attend to coiler jaw adjustment fast and provide improvement in production of skelp mills. The system is simple to operate and does not necessitate requirement of skilled man power.
Full Text The present invention relates to a control system for coiler jaw positioning operation for skelp mill and in particular to a control system for coiler jaw positioning operation which would be operable from remote locations will be reliable and will not subject the operator to harsh environments and would thus be also safe and simple to operate.
It is presently known to carry out coiler jaw positioning operation manually by an operator from a control post. Once the front end of the skelp reaches the pinch roll, the operator adjusts position by inching operation which involves repeated periodic starting and stopping of the motor within seconds. After 2-3 inching, when the jaw is aligned, skelp front end is moved forward through the jaw.
Such conventional manually operated method of controlling the coiler jaw positioning operation for skelp mills suffer from drawbacks/disadvantages which are discussed hereunder:
a) manual adjustment of coiler jaw takes around 15 sec per coil which is both,
time and labour extensive.
b) manual adjustment of coiler jaw requires several inching operation for
positioning of the jaw and thus reduces motor life.
c) Operator is subjected to work in harsh environment near hot skelp at 700°C
which is hazardous.
It is thus the basic object of the present invention to provide a control system for coiler jaw positioning which would avoid the aforediscussed problems/disadvantages of presently known manual adjustment of coiler jaws in skelp mills.
Another object of the present invention is to provide a control system of coiler jaw adjustment which can be attended fast and thereby provide for improvement in the production of skelp mills.
Yet another object of the present invention is to provide a control system for coiler jaw adjustment which would simple to operate and would not necessitate the requirement of skilled manpower.
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Thus according to the present invention there is provided a control system for coiler jaw adjustment in skelp mill comprising : coiler drum operatively connected to a motor and having atleast four jaws; means for feeding the skelp end to the coiler jaw for coiling of the skelp thereon said coiler drum ;
control means comprising means for varying the speed of the motor rotating said coiler drum ;
means for sensing the position of said coiler drum jaw with respect to said skelp end and feeding said skelp end into said jaw when both are in alignment for coiling of said skelp on said coiler drum.
It is thus possible by way of the above disclosed control system of the invention to provide for controlled and fast coiling of skelp on coiler drum from remote locations avoiding manual reliance and unsafe and hazardous conditions.
According to one aspect of the present invention, the said means for sensing of the coiler drum jaw position comprise mechanical image sensing means comprising :
motor means operatively connected at one end of its rotary shaft to said coiler drum and the other end to a circular disk being a mechanical image of said coiler drum having openings positioned corresponding 4o that of the coiler jaws ;
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means to operate said motor and its operatively connected coiler drum and
circular disk at variable speeds and having brake means for stopping the rotary
motion of said coiler drum/circular disks ;
means for transmitting infra red ; and
means for receiving infra red such that when said circular disk opening being
mechanical image of said coiler drum jaws are in alignment with said skelp end
disposition, the infra red is transmitted through said circular disk opening and
received by said means for receiving infra red.
said control means adapted to receive signals from said infra red receiving
means to effectuate the desired motor condition to enable feeding of said skelp
end into said coiler drum jaw and further coiling of said skelp on said coiler drum.
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Preferably, the motor means is operatively connected to said coiler drum and said circular disk through gear means to facilitate controlled motion of the coiler drum and its mechanical image positioned at remote locations.
According to another aspect of the present invention, the said means for sensing the coiler drum jaws position comprise mechanical image sensing means comprising :
motor means operatively connected at one end of its rotary shaft to said coiler drum and at its other end to a magnetic sensor being a mechanical image of position of the jaw openings of the coiler drum and a magnetic switch (proximity) adjacent thereto;
means to operate 'said motor and its operatively connected coiler drum and magnetic sensor at variable speeds and having brake means for stopping the rotary motion of said coiler drum/magnetic disk;
switching means for identifying the proximity of said magnetic sensor position corresponding to said coiler drum jaw position such that when said magnetic sensor opening being mechanical image of said coiler drum jaw opening is in alignment with said skelp end disposition, the proximity switching means is adapted to transmit signals to control means adapted to receive signals from said proximity switching means to effectuate the desired motor speed control to enable feeding of said skelp end into said coiler drum jaw and further coiling of said skelp on said coiler drum..
It is thus possible by way of the aforediscussed control system of the invention to provide for sensing of the jaw opening position from remote locations by way of a reliable and easy to operate control mechanism.
The details of the invention, its objects and advantages are explained in greater detail in relation to non-limiting exemplary embodiments of the control system of the invention with referance to the accompanying figures wherein
Fig. 1 is a general lay out of a skelp mill and the coiler drum in relation thereto ;
Fig. 2 is a sectional view of a coiler drum with jaws and slots provided therein ;
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Fig. 3 is a schematic diagram of the coiler jaw positioning control system of the invention ;
Fig. 4A is an embodiment of coiler jaw opening sensing means used in the system of the invention ;
Fig. 4B is a another embodiment of the coiler jaw opening sensing means used in the system of the inventon.
Fig. 5 is a circuit diagram of means for achieving varying motor speed used in the system of the invention ; and
Fig. 6 is a flow-chart of the control system of the present invention.
Reference is first invited to figure 1 which shows the disposition of the skelp end in relation to the coiler drum opening. The slabs are fed to the reheating furnace and after requisite heating are rolled by 5 roughing and 6 finishing stands. After rolling from the finishing stands is over, adjacent metal goes to two beds alternatively, namely bed-1 and bed-2 for slow cooling. There are two coilers, one for each bed, for coiling the skelp. After the metal reaches the pinch roll, the skelp end is required to be fed to the coiling jaw. There are usually 4 nos. of jaws,, for each coiler, separated 90° apart.
Fig. 2 shows the jaws position with respect to coiler drum.
Under the presently known practice the skelp end is aligned to the jaw opening by the operator manually by operating the coiler motor by inching operation by a push button, so as to rotate the coiler jaws slowly and align them in line for proper entry of skelp. The coiler drum is rotated till the entire skelp is wrapped in a coil. After this, the jaw is lowered and coil pusher is operated to push the coil into a conveyor. The pusher motor rotates in one direction and in forward stroke it pushes the coil and in reverse stroke it comes back to the original position. Forward travel time is 4 sec. and the reverse travel time is 2 sec. with pusher
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motor there is a cam switch which gives contact at 180° and 355° to 5°. Coil pusher starts only when, the coiler jaws is in the lower limit. It can not be started when the jaw is in the upper limit.
The control system of the.present invention provides for effectuating the above operation of feeding the skelp end in the coiler jaw by utilizing (i) jaw position sensing device, (ii) speed control system for the motor to rotate the coiler drum and (iii) control system for sequencing the operations.
Since on the top surface of the coiler drum, it is not possible to install any sensor, as this area is hazardous area the control system of the invention uses a jaw position sensing device having remote sensing of the mechanical image of the coiler drum to achieve such purpose.
Fig. 3 shows the schematic diagram of the control system in accordance with the present invention. As shown in Fig. 3, the coiler motor (CM) is horizontal and coiler drum (CD) is vertical. Power is transmitted from motor (CM) to drum (CD) by a gear box (GB1) of ratio 91:22. The other side of the motor (CM) is having a brake drum (BD). Another gear box (GB2) of ratio 91:22 is provided on the motor shaft (MS) near the brake drum (BD). As shown in Fig 4A in the sensing shaft (SS) of the gear box (GB2) one circular disk (CID) is mounted. The circular disk (CID) is having four holes (HO). Each hole (HO) is having a diameter of approx 2 ., mm. Each hole (HO) corresponds to the blank position slot (SL) of the jaw. An infra-red transmitter (IR/TX) and Receiver (IR/RX) is set between which the circular disk (CID) rotates. The transmitter (IR/TX) emits an infra-red (IR) beam of diameter of about 1 mm. when the jaw is aligned, the transmitted beam pass through the hole (HO) of the circular disk (CID) and the receiver (RX) detects the beam indicating that the jaw has been aligned on the coiler drum.
For alignment of the jaw opening the coiler motor (CM) is run at slow speed. This is because the moment the jaw alignment signal is received from infra-red receiver (RX) the motor is stopped.without much overshoot. Slow rotation of the motor is achieved by adding armature resistance (AMR) and with fixed DC supply across the armature. Normalty the resistance will not be in the armature circuit.
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Only during sSow rotation of the motor the armature resistance (AMR) will be in the circuit. Resistance is taken out from the circuit by a contactor, which is energised by a Programmable Controller (PLC). The desired circuitry is illustrated in accompanying figure 5. Nominal speed of motor is 1400 RPM. The speed can be varied from 500 RPM to 1400 RPM by varying the field this takes evens 2 sec as discussed earlier. It is found that with an additional about 6 ohms in armature circuit, time taken for one rotation of coiler jaw is about 8 sec. Since there are four jaws, there will be four aligned position on the jaws. Therefore, the jaws are to align with in 2 sec. Hence, an additional resistance of 6 ohms has been added in the armature circuit as shown on Fig. 5. This gives the speed of jaw of 7.5 RPM and motor speed of 31.02 RPM.
Speed control can also be done by variable voltage DC source from a thyristor converter. In that case, the programmable controller (PLC) shall generate the speed reference of 31 RPM during slow rotation of the motor. This method is more costly than the armature resistance control method.
DC power is fed to the infra-red transmitter only when slow rotation is desired. This increases the life of the transmitter-receiver set.
Alternatively as shown in Fig. 4B instead of using a circular disk and the infra-red transmitter and receiver set, a magnetic sensor (MS) with a proximity switch (PS) can also be used as an alternate method of position sensing.
An illustration (non-limiting) of the control system for sequencing the operations is realized through the Programmable Controller (PLC). The sequence of operation is detailed as follows :
a) Coiling is done on the coiler drum.
b) Jaws move down.
c) Coil pusher pushes the coil on the conveyor.
d) Coil pusher starts coming back. One contact is obtained when coil pusher is
at 180°. This is an input to the programmable controller.
e) Infra-red transmitter and receiver is powered.
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f) Motor armature is fed to 460 V DC and the armature resistance is in the
circuit. Motor runs at slow speed. Armature resistance is brought to the circuit
by opening a line contactor. The contactor is made ON/OFF by one of the
output of the programmable controller.
g) Within a rotation of 90° of the coiler drum, the alignment signal is obtained
from the infra-red receiver unit. This is an input to programmable controller.
h) Once the jaw alignment is done, motor is stopped by dynamic braking and by
mechanical brake.
i) Skelp front end is fed to the pinch roll and then it enters into the jaws, j) Coiler motor is started with slow sped (500 RPM) by higher field current, k) Slowly the field current is reduced and motor speed goes up to 1400 RPM. I) Towards the end the motor speed is brought down to 500 RPM. m) Coiling is done on the coiler drum.
This process is repeated. In case an emergency stop button is pushed, the process is stopped at that point. A flow chart of the above sequencing operation followed by the system illustrated in Fig. 6.
Thus as detailed hereinbefore the control system of the invention basically utilizing (i) Jaw position sensing system, (ii) speed control system for the motor
a
and (iii) control system for sequencing the operations to achieve coiler jaw positioning from remote locations without -subjecting the operator to hazardous and unsafe environmental for operations.
The jaw position sensing system comprising
i) the gear box mounted on the motor shaft on brake drum side with a gear
ratio of 91:22; ii) Circular disk of diameter in the range of 200 to 400 mm preferably 300 mm
and thickness 4 to 8 mm preferably 5 mm made of preferably bakelite
sheet;
iii) Infra-red transmitter and receiver with power supply such as 24 V DC ; and iv) Mounting arrangement for said transmitter and receiver.
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The speed control system for the motor used in the system of the invention
comprising
i) additional armature of 3 to 12 ohms preferably 6 ohms for speed control;
ii) line contactor for operatively connecting the resistance into armature
circuit or disconnecting the same from the circuit as and when desired ; iii) atleast one auxiliary relay to drive the line contactor from the
programmable controller; iv) coil pusher contact substantially at 180° movement for initiating the
process.
The control system for sequencing the operations consists of the following : i) at least one programmable controller such as S5 90U of Siemens make. ii) relays having say 24V DC coil for interfacing with the process, iii) Emergency stop input from field.
The control system of the invention thus provides for the following distinguish functional attributes for simple and safe remote sensing of coiler jaw adjustment for skelp mills and the like :
a) coiler jaw position sensing mechanism using mechanical image ;
b) running the motor at very slow speed while positioning ;
c) jaw positioning while coiled pusher is traversing back after pushing a coil
d) safety interlocks-with coil-pusher mechanism.
It is thus possible by way of the above discussed system of the invention to effectively carry out coiler jaw positioning with precision without wastage of essential production time thereby enhancing the production capacity of the mill.
Also the system provides for increase in motor life by reducing several inching operation and less maintenance time as control of the motor is through a programmable controller.
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The system of the invention is thus a cost effective solution for jaw positioning and directed to essentially avoid exposing valuable human life to adverse working environments and therefore is safe and user friendly.
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WE CLAIM:
1. A control system for coiler jaw adjustment in skelp mill comprising :
coiler drum (CD) operatively connected to a motor (CM) and having atleast four
jaws;
means for feeding the skelp end to the coiler jaw for coiling of the skelp thereon
said coiler drum (CD);
control means comprising means for varying the speed of the motor rotating said
coiler drum (CD);
means for sensing the position of said coiler drum jaw with respect to said skelp
end and feeding said skelp end into said jaw when both are in alignment for
coiling of said skelp on said coiler drum.
2. A control system as claimed in claim 1 wherein said means for sensing of the
coiler drum jaw position comprise mechanical image sensing means comprising :
motor means operatively connected at one end of its rotary shaft (MS) to said coiler drum and the other end to a circular disk (CID) being a mechanical image of said coiler drum having openings positioned corresponding to that of the coiler jaws ;
means to operate said motor and its operatively connected coiler drum (CD) and circular disk (CID) at variable speeds and having brake means adapted for stopping the rotary motion of said coiler drum/circular disks ; means for transmitting infra red ; and
means for receiving infra red such that when said circular disk (CID) opening being mechanical image of said coiler drum jaws are in alignment with said skelp end disposition, the infra red is transmitted through said circular disk (CID) opening and received by said means for receiving infra red.
said control means adapted to receive signals from said infra red receiving means to effectuate the desired motor condition to enable feeding of said skelp end into said coiler drum jaw and further coiling of said skelp on said coiler drum (CD).
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3. A control system as claimed in anyone of claims 1 or 2 wherein said motor (CM)
means is operatively connected to said coiler drum' (CD) and said circular disk
(CID) through gear means to facilitate controlled motion of the coiler drum (CD)
and its mechanical image comprising said circular disk (CID) with -openings
positioned at remote locations.
4. A control system as claimed in claim 1 wherein said means for sensing the coiler
drum jaws position comprise mechanical image sensing means comprising :
motor means operatively connected at one end of its rotary shaft (MS) to said coiler drum (CD) and at its other end to a magnetic sensor (MS) comprising a mechanical image of position of the jaw openings of the coiler drum and a magnetic switch (proximity) (PS) adjacent thereto ;
means to operate said motor (CM) and its operatively connected coiler drum (CD) and magnetic sensor (MS) at variable speeds and having brake means for stopping the rotary motion of said coiler drum (CD)/magnetic disk ; switching means for identifying the proximity of said magnetic sensor position corresponding to said coiler drum jaw position such that when said magnetic sensor opening being mechanical image of said coiler drum jaw opening is in alignment with said skelp end disposition, the proximity switching means (PS) is adapted to transmit signals to control means the later adapted to receive signals from said proximity switching means and effectuate the desired motor speed control to enable feeding of said skelp end into said coiler drum jaw and further coiling of said skelp on said coiler drum.
5. A control system as claimed in anyone of claims 1 to 4 wherein for achieving slow
rotation of the motor an armature resistance (AMIR) is provided and fixed DC
supply is provided across said armature, said armature resistance adapted such
that only during slow rotation of the motor the armature resistance is comprised in
the armature circuit.
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6. A control system as claimed in claim 6 wherein for adapting the inclusion of the
armature resistance (AMR) in the armature circuitry and its exclusion from the
said circuitry when not desired, a contactor is provided which is energised by a
programmable controller (PLC).
7. A control system as claimed in anyone of claims 1 to 6 wherein said motor speed
is adapted to be varied from 500 RPM to 1400 RPM by means for varying the
resistance in the circuit.
8. A control system as claimed in anyone of claims 1 to 7 wherein the means for
speed control comprise variable voltage DC source from a thyristor converter
operatively connected to said programmable controller (PLC).
9. A control system as claimed in anyone of claims 1 to 8 wherein said means for
sensing the jaw position comprise
i) gear box (GB2) mounted on the motor shaft on brake drum side with a gear
ratio of 91:22 ; ii) circular disk of diameter in the range of 200 to 400 mm preferably 300 mm
and thickness 4 to 8 mm preferably 5 mm ; iii) infra-red transmitter (IR/TX) and receiver means (IR/RX) with power supply ;
and iv) mounting arrangement for said transmitter and receiver means.
10.A control system as claimed in claim 9 wherein said circular disk (CID) is obtained of bakelite.
11. A control system as claimed in anyone of claims 1 to 10 wherein said programmable controller is adapted to actuate the coil pusher contact substantially at 180° movement for initiating the process of coiling when said coiler jaw positioning is established.
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12. A control system as claimed in anyone of claims 1 to 11 comprising :
i) at least one programmable controller;
ii) relay means for interfacing with the sequence of operating process ;
iii) means for emergency stop input from field.
13. A control system or coiler jaw adjustment in skelp mill a
substantially as
hereindescribed and illustrated with reference to the accompanying figures.
The control system for coiler jaw positioning operation for skelp mill operable for remote location avoiding manual reliance and unsafe and hazardous condition comprising coiler drum (CD) operatively connected to a motor (CM) and having atleast four jaws; means for feeding the skelp end to the coiler jaw for coiling of the skelp thereon said coiler drum (CD); control means comprising means for varying the speed of the motor rotating said coiler drum ; means for sensing the position of said coiler drum jaw with respect to said skelp end and feeding said skelp end into said jaw when both are in alignment for coiling of said skelp on said coiler drum. It is thus possible by way of the system of the invention to attend to coiler jaw adjustment fast and provide improvement in production of skelp mills. The system is simple to operate and does not necessitate requirement of skilled man power.


Documents:

00037-cal-2000 abstract.pdf

00037-cal-2000 claims.pdf

00037-cal-2000 correspondence.pdf

00037-cal-2000 description(complete).pdf

00037-cal-2000 drawings.pdf

00037-cal-2000 form-1.pdf

00037-cal-2000 form-18.pdf

00037-cal-2000 form-2.pdf

00037-cal-2000 form-3.pdf

00037-cal-2000 letters patent.pdf

00037-cal-2000 p.a.pdf


Patent Number 206407
Indian Patent Application Number 37/CAL/2000
PG Journal Number 17/2007
Publication Date 27-Apr-2007
Grant Date 27-Apr-2007
Date of Filing 21-Jan-2000
Name of Patentee STELL AUTHORIY OF INDIA
Applicant Address ISPAT BHAWAN,LODI ROAD,NEW DELHI-110 003,INDIA,
Inventors:
# Inventor's Name Inventor's Address
1 ASHOKE KUMAR PAUL RESEARCH AND DEVELOPMENT CENTER FOR IRON AND STEEL,STELL AUTHORIY OF INDIA LTD.,DORANDA,RANCHI-834 002,
2 ABHIJIT CHATTERJEE RE-SEARCH AND DEVELOPMENT CENTER FOR IRON AND STEEL,STELL AUTHORIY OF INDIA LTD..,DORANDA,RANCHI-834 002,STATE OF BIHAR INDIA.
3 ASIM KUMAR SAHU RE-SEARCH AND DEVELOPMENT CENTER FOR IRON AND STEEL,STELL AUTHORIY OF INDIA LTD..,DORANDA,RANCHI-834 002,STATE OF BIHAR INDIA.
4 GAUTAM MAJUMDER DURGAPUR STEEL PLANT,STEEL AUTHORITY OF INDIA
5 PLABAN KUMAR GHOSH DURGAPUR STEEL PLANT,STEEL AUTHORITY OF INDIA LTD.., STATE OF W.B, IMDIA
6 BRAJENDRA KUMAR SANTRA RE-SEARCH AND DEVELOPMENT CENTER FOR IRON AND STEEL,STELL AUTHORIY OF INDIA LTD..,DORANDA,RANCHI-834 002,STATE OF BIHAR INDIA.
7 SUSHIL CHANDRA KHAN RE-SEARCH AND DEVELOPMENT CENTER FOR IRON AND STEEL,STELL AUTHORIY OF INDIA LTD..,DORANDA,RANCHI-834 002,STATE OF BIHAR INDIA.
PCT International Classification Number B21C 47/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA