Title of Invention

A DEVICE FOR CONTROLLING AUTOMATICALLY THE DEPTH OF THE VERTICAL AND HORIZANTAL LOOPS FORMED IN STEEL,WIRE RODS DURING ROLLING

Abstract A device for controlling automatically the depth of the vertical and horizontal loops formed in steel wire rods during rolling thereof in the rolling mill of a steel plant, characterised in that the device comprises: (a) a vertical loop sensor VLS of a conventional type for producing electrical signals corresponding to the depths of the vertical loop VL; (b) a horizontal loop sensor HLS of a conventional type for producing electrical signals corres;onding to the depths of the horizontal loop HL; (c) three hot metal detectors HMD 7, HMD 16 and HMD 20 of conventional types positioned adjacent to the respective stands STAND 7, STAND 16 and STAND 20 of a known rolling machine for detecting the presence of the wire rod therein and producing the corresponding electrical signals; (d) a vertical loop control unit VLCU for adjusting the speed of the drawing rolls in the appropriate stands in response to the signals received from the vertical loop sensor VLS and the hot metal detectors; and (e) a horizontal loop control unit HLCU for adjusting the speed of the drawing rolls in the appropriate stands in response to the signals received from the horizontal loop sensor HLS and hot metal detectors, the said units (a) to (e) being connected for functioning in an inter-dependent manner.
Full Text The present invention relates to a device for controlling automatically the depth of the vertical and horizontal loops formed in steel wire rods during rolling thereof in a rolling mill of steel plants.
The invention relates more particularly to a device in which the depths of loops formed in the vertical and horizontal planes of steel wire rods during rolling are sensed by convention sensors to produce corresponding electrical signals, an electronic control unit is provided to amplify the difference of the sensed signals from the corresponding reference signals and generate tine delays required for applying the amplified output signals to control the speed of drawing rolls for maintaining the depths of the said loops formed in the wire rods at the preset levels and also for lifting the loops left at the back ends of the wire rods.
In the production of wire rods in the wire rod rolling mill of steel plants, billets of typical cross section 85 x 85 mm and length 12 m are rolled in a series of stands each having a pair of drawing rolls, arranged in tandem and finally coiled in a coiler machine.
A typical wire rod rolling mill is provided with 23 rolling stands and coiler machine of Eden Boron type and contains four strands each of twentythree stands. The hot rolled wire rods produced in the mill are of diameters such as 5.5, 6.0, 8.0 and 10.0 mm.
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For precise control of diameter and ovality of the wire rods to be within acceptable tolerance limits, it is necessary to maintain the depths of the vertical and horizontal loops formed in the wire rods at intermediate stages of the rolling operation to be at predetermined levels as shown in Table I and to lift the loops present in the back ends of the wire rods.
At present the control of loop depths and lifting of the loops at the back ends of wire rods are both performed manually by adjusting the speed of the appropriate drawing rolls at appropriate times. Since the mannual control is subject to unavoidable variations depending on the skill of the operating personnel, a sizeable proportion of the wire rods produced are found to be of diameter and ovality beyond the prescribed tolerance limits and an appreciable quantity of scraps in the form of cobbles is found to be generated in rolling plants.
The object of the present invention is to provide a device in replacement of the existing manual method for maintaining the depth of loops as well as lifting of the loops at the back ends of wire rods with a view to reducing the quantity of rejections of off-standard rods and scrap generation in the form of cobbles.
Thus the invention provides a device for controlling automatically the depth of the vertical and horizontal loops formed in steel wire rods in the rolling mill of a stell plant characterised in that the device comprises: (a) a vertical loop sensor of a conventional type for producing electrical signals corresponding to the depths of the vertical loop;
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(b) a horizontal loop sensor of a conventional type for producing electrical signals corresponding to the depths of the horizontal loop; (c) three hot metal detectors of conventional types positioned adjacent to the respective stands of a known rolling machine for detecting the presence of the wire rod therein and producing the corresponding electrical signals; (d) a vertical loop control unit for adjusting the speed of the drawing rolls in the appropriate stands in response to the signals received from the vertical loop sensor and the hot metal detectors; and (e) a horizontal loop control unit for adjusting the speed of the drawing rolls in the appropriate stands in response to the signals received from the horizontal loop sensor and hot metal detectors, the said units (a) to (e) being connected for functioning in an interdependent manner.
The invention is described fully and particularly in an unrestrictive manner with reference to the accompanying drawings in which -
Figure 1 is a schematic view of one strand of a wire rod in a rolling mill and of the vertical and horizontal loops formed in the wire rod during the rolling operation;
Figure 2 is the schematic t&ock diagram of the vertical loop controller unit used for controlling the depth of the vertical loop; and
Figure 3 is the schematic block diagram of the horizontal loop controller unit used for controlling the depth of the horizontal loop.
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Referring to Fig. 1 the vertical loop VL is formed in the space between STAND 19 and STAND 20, and the horizontal loop
HL Is formed between STAND 21 and STAND 22. A hot metal detector
HMD7 is positioned adJacent to STAND 7 (not shown); and hot metal
detectors HMD 16 and HMD 20 are positioned adjacent to STAND 16
and STAND 20 respectively. The wire rod WR is drawn through a pair of drawing rolls DR contained in each STAND. A Pair of fixed guide angles GA for guiding the wire rod is used In tandem in the space between each pair of adjacent STANDS, except the space between STAND 19 and STAND 20, and that between STAND 21 and STAND 22. For guiding the wire rod in the space between STAND 19 and STAND 20, one upper and one lower guide angles (not shown) are provided, of which the upper one is kept fixed in position and the lower one is movable side ways by actuating a solanoid. For guiding the wire rod in the space between STAND 21 and STAND 22, a horizontal table (not shown) is provided to support the wire rod thereon.
When the leading end of wire rod enters into STAND 20, the hot metal detector HMD 20 is put on to actuate a solenoid (not shown) which shifts the movable lower guide angle, supporting the wire rod in the space between STAND 19 and STAND 20, sideways allowing thereby the wire rod to sag downwards by its own weight for forming the vertical loop VL. After a delay of about 2 sec the speed of drawing rolls in each
of STAND 20 to STAND 23 is gradually reduced till the depth of

the vertical loop VL attains a predetermined limit as shown in Table I. After a
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delay of 4 sec the speed of drawing rolls in STAND 22 is further reduced gradually by varying the dc voltage supplied to the driving motors to allow formation of the horizontal loop HL by means of a mechanical guide (not shown) which pushes the wire rod lying on the horizontal table sideways in the space between STAND 21 and STAND 22 till the horizontal loop formed is of a predetermined depth*
After the back end of the wire rod leaves STAND 7, the hot metal detector HMD 7 is put off to produce a signal which increases the speed of drawing rolls in each of STAND 20 to STAND 23 slowly to reduce the depth of the vertical loop. After the back end of the wire rod leaves STAND 16 the hot metal detector HMD 16 is put off to produce a signal which increases the speed of drawing rolls in STAND 20 at a relatively fast rate to lift the vertical loop at the back end of the wire rod. After the back end of the wire rod leaves the drawing rolls in STAND 20, the hot metal detector HMD 20 is put off to produce a signal which increases the speed of drawing rolls in STAND 22 and STAND 23 each, and also actuates the mechanical guide to remove the horizontal loop at the back end of wire rod before being wound in coil CL*
A vertical loop sensor VLS and a horizontal loop sensor HLS, both of conventional type, are mounted in the space between STAND 19 and STAND 20, and that between STAND 21 and STAND 22 respectively to produce electrical signals corresponding to the depth of the loops formed in the vertical and horizontal directions.
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Referring to Fig. 2, in the vertical loop control unit VtCXJ the output signal of vertical loop sensor VtS and a reference signal from potentiometer POT 1 are supplied at the input of the electronic amplifier unit EAU 1 comprising three separate modules of conventional circuitry, of which one module being a proportional amplifier amplifies the difference between the signals from VLS and POT 1 by means of known operational amplifiers and produces an output signal current of upto 10 mA, till the back end of a wire rod remains within the grip of drawing rolls in STAND 19, another module provides a signal output suitable for lifting the back end of the wire rod when lying in the space between STAND 19 and STAND 2p, and another module generates the time delays required for changing the speed of drawing rolls in each of STAND 20 to STAND 23 in response to the signals produced by the hot metal detectors HMD 7, HMD 16 and HMD 20 for controlling the performance of the rollitismachine in the manner as described herein before*
The output signals of the electronic control unit ECU 1 are passed through the control panel CPL to magnetic amplifier/ thyristor unit MAT to produce AC signals of 76 to 86 volts, which are applied through potentiometer POT 2 to the driving units of the drawing rolls in each of STAND 20 to STAND 23 for controlling the speed thereof in predetermined manners.
Referring to Fig, 3, in the horizontal loop control unit HLCU the output signal of horizontal loop sensor HLS and a reference signal from potentiometer POT 3 are supplied at the
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input of electronic amplifier unit EAU 2 which acting as a conventional proportional amplifier and a comparator with known operational amplifiers, produces an output signal corresponding to the difference of the signals obtained from HLS and POT 3, which is supplied to the power amplifier unit PAU which supplies power through terminals A1 and A2, and resistors R1, R2, R3 to tachogenerator TG1 for controlling the speed of drawing rolls in STAND 22, and through terminals A1 and A2, and resistors R1, R4, R5 to tachogenerator TG2 for controlling the speed of drawing rolls in STAND 23*
The performance of the invented system has been studied over a period in a steel plant. The following advantages have been attained by using the system :-
1* The shape and depth of the vertical and horizontal
as shown in Table I. loops have been controlled automatically to the preset limits
2. The back ends of wire rods have been straightened automatically.
3. The rejections of wire rods have been reduced significantly, i.e. around 35-4O# •
* 4. The generation of scraps in the form of cobbles has decreased appreciably.
5. The tripping of the driving units of drawing rollers due to lifting of the back ends of wire rods has been eleminated.
6. The system has been found to be cost effective.
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Table I
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Typical depths of vertical and horizontal loops of rods of different sizes.


We Claim ;-
1. A device for controlling automatically the depth of the vertical and horizontal loops formed in steel wire rods during rolling thereof in the rolling mill of a steel plant, characterised in that the device comprises: (a) a vertical loop sensor VLS of a conventional type for producing electrical signals corresponding to the depths of the vertical loop VL; (b) a horizontal loop sensor HLS of a conventional type for producing electrical signals corresponding to the depths of the horizontal loop HL; (c) three hot metal detectors HMD 7, HMD 16 and HMD 20 of conventional types positioned adjacent to the respective stands STAND 7, STAND 16 and STAND 20 of a known rolling machine for detecting the presence of the wire rod therein and producing the corresponding electrical signals;
(d) a vertical loop control unit VLCU for adjusting the speed
of the drawing rolls in the appropriate stands in response to
the signals received from the vertical loop sensor VLS and the
hot metal detectors; and (e) a horizontal loop control unit HLCU
for adjusting the speed of the drawing rolls in the appropriate
stands in response to the signals received from the horizontal
loop sensor HLS and hot metal detectors, the said units (a) to
(e) being connected for functioning in an inter-dependent
manner.
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2. The device as claimed in claim 1, wherein the vertical
loop control unit comprises an electronic amplifier unit EAU 1,
a control panel CPL and a magnetic amplifier/thyristor unit
MAT.
3. The device as claimed in claim 2, wherein the
electronic amplifier unit comprises three separate modulesjpf which
one is a proportional amplifier for amplifying difference
signals, another provides output signal suitable for lifting
the back end of the wire rod when required and the remaining one is a generator of time delays required for the operation of the- device in the predetermined manner,
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4. The device as claimed in claim 1, wherein the
horizontal loop control unit comprises an electronic amplifier
unit EAU 2 and a power amplifier unit PAU.
5. A device for controlling automatically the depth of
vertical and horizontal loops formed in steel wire rods during
rolling thereof in a rolling mill of a steel plant, substantially
as herein described with reference to the accompanying drawings.
A device for controlling automatically the depth of the vertical and horizontal loops formed in steel wire rods during rolling thereof in the rolling mill of a steel plant, characterised in that the device comprises: (a) a vertical loop sensor VLS of a conventional type for producing electrical signals corresponding to the depths of the vertical loop VL; (b) a horizontal loop sensor HLS of a conventional type for producing electrical signals corres;onding to the depths of the horizontal loop HL; (c) three hot metal detectors HMD 7, HMD 16 and HMD 20 of conventional types positioned adjacent to the respective stands STAND 7, STAND 16 and STAND 20 of a known rolling machine for detecting the presence of the wire rod therein and producing the corresponding electrical signals; (d) a vertical loop control unit VLCU for adjusting the speed of the drawing rolls in the appropriate stands in response to the signals received from the vertical loop sensor VLS and the hot metal detectors; and (e) a horizontal loop control unit HLCU for adjusting the speed of the drawing rolls in the appropriate stands in response to the signals received from the horizontal loop sensor HLS and hot metal detectors, the said units (a) to (e) being connected for functioning in an inter-dependent manner.

Documents:

01513-cal-1998-abstract.pdf

01513-cal-1998-assignment.pdf

01513-cal-1998-claims.pdf

01513-cal-1998-correspondence.pdf

01513-cal-1998-description(complete).pdf

01513-cal-1998-drawings.pdf

01513-cal-1998-form-1.pdf

01513-cal-1998-form-18.pdf

01513-cal-1998-form-2.pdf

01513-cal-1998-form-3.pdf

01513-cal-1998-form-5.pdf

01513-cal-1998-letters patent.pdf

01513-cal-1998-p.a.pdf

1513-cal-1998-granted-abstract.pdf

1513-cal-1998-granted-claims.pdf

1513-cal-1998-granted-description (complete).pdf

1513-cal-1998-granted-drawings.pdf

1513-cal-1998-granted-form 2.pdf

1513-cal-1998-granted-specification.pdf


Patent Number 200484
Indian Patent Application Number 1513/CAL/1998
PG Journal Number 08/2007
Publication Date 23-Feb-2007
Grant Date 23-Feb-2007
Date of Filing 25-Aug-1998
Name of Patentee STEEL AUTHORITY OF INDIA LIMITED,
Applicant Address STEEL AUTHORITY OF INDIA LIMITED, RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL HAVING ITS REGISTERED OFICE AT ISPAT BHAWAN, LODHI ROAD,NEW DELHI-110003,A GOVERNMENT ENTERPRISE. NEW DELHI-110003
Inventors:
# Inventor's Name Inventor's Address
1 ASHOK KUMAR PAUL B-36,SAIL SATALLITE TOWNSHIP, P.O-DORANDA, RANCHI-83404 AN INDIAN NATIONAL
2 SAURABH DIXIT B-36,SAIL SATALLITE TOWNSHIP, P.O-DORANDA, RANCHI-83404
3 GURDIP SIGH SANGAR B-36,SAIL SATALLITE TOWNSHIP, P.O-DORANDA, RANCHI-83404 AN INDIAN NATIONAL
4 SUSHIL KR SABLOK B-36,SAIL SATALLITE TOWNSHIP, P.O-DORANDA, RANCHI-83404 AN INDIAN NATIONAL
5 BIJOY BHOWMIK B-36,SAIL SATALLITE TOWNSHIP, P.O-DORANDA, RANCHI-83404 AN INDIAN NATIONAL
6 SUBROTO SINHA B-36,SAIL SATALLITE TOWNSHIP, P.O-DORANDA, RANCHI-83404 AN INDIAN NATIONAL
7 BRAJENDRA KR SANTRA B-36,SAIL SATALLITE TOWNSHIP, P.O-DORANDA, RANCHI-83404 AN INDIAN NATIONAL
8 SUSHIL CHANDRA KHAN B-36,SAIL SATALLITE TOWNSHIP, P.O-DORANDA, RANCHI-83404 AN INDIAN NATIONAL
9 NIRBHOR NEOGI B-36,SAIL SATALLITE TOWNSHIP, P.O-DORANDA, RANCHI-83404 AN INDIAN NATIONAL
10 GOPAL JIVAN MAHAJAN B-36,SAIL SATALLITE TOWNSHIP, P.O-DORANDA, RANCHI-83404 AN INDIAN NATIONAL
11 SUSHANTA MAJUMDAR B-36,SAIL SATALLITE TOWNSHIP, P.O-DORANDA, RANCHI-83404 AN INDIAN NATIONAL
PCT International Classification Number B23D 79/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA