FIELD OF THE INVENTION
The present invention relates to a system for sliding of sensors for cutting the slab
at different desired lengths with a maximum error of 0 to +20 mm in continuous
casting of steel plant. More particularly, the present invention relates to developing
a simple, low cost but highly reliable system to adjust the sensors for measuring
and effecting cutting of the slabs at desired lengths to meet the varying base
lengths requirement of slabs for further processing.
BACKGROUND OF THE INVENTION
In continuous casting plant of the applicants, it produces cast slabs on continuous basis
which needs to be cut at required lengths for further processing in rolling mills. The
slabs are cut into different smaller base lengths ranging from 5.5 m to 10.5 m at
intervals of 30 mm by gas cutting in order to fulfill the demand of plate Mill and other
external customers. Over length slabs produce scrap and also jam the reheating
furnaces of plate mill while short length slabs reduce the yield. Earlier the slab length
was measured by using a measuring scale installed just adjacent to roll table. As soon
as front end of slab was crossing the desired length then gripping/ cutting activities
starts. After cutting the slab, the trolley in which gas cutting torch is kept, returns to
its initial reference rest position and get ready for next cutting cycle by gripping the
slab by its own gripping mechanism. Earlier a number of length measuring systems
such as contact type shaft encoder, photosensor based measurement were tried but
could not cut the slab at desired length because of slippage and decaying of roll
diameter and needed continuous calibration. The cutting performance of the existing
slab cutting systems also suffered due to operating environmental factors like sparkles
during cutting, influence due to variation in luminosity of metal etc. Difficulties were
also faced with maintaining Laser based length measuring system, Video based
dimension measuring systems prevailing in the existing art.
OBJECTS OF THE INVENTION
The basic object of the present invention is thus directed to providing a system for
sliding of sensors for cutting the slab at different desired lengths with a maximum error
of 0 to +20 mm in continuous casting of steel plant.
A further object of the present invention directed to providing a system for sliding of
sensors for cutting the slab at different desired lengths which would favour correct
measurement and cutting of slab length to desired precision so as to avoid over or
under length and thereby eliminate chances of scrap generation, jamming of reheat
furnace in plate mill or reduce yield.
A still further object of the present invention directed to providing a system for sliding
of sensors for cutting the slab at different desired lengths wherein accuracy of length
measurement and cutting of slab would be unaffected due to slippage of slab on roll
table or decaying of roll diameter.
A still further object of the present invention directed to providing a system for sliding
of sensors for cutting the slab at different desired lengths wherein sensor performance
would be free of influence due to sparkles during gas cutting or variation in luminosity
of metal while sensing with light based unit.
A still further object of the present invention directed to providing a system for sliding
of sensors for cutting the slab at different desired lengths which would have simple and
user friendly construction and operation of IR emitter and receiver based system and
easy to maintain unlike the problematic calibration in laser or video based complex
system and difficult to maintain length measuring systems.
A still further object of the present invention directed to providing a system for sliding
of sensors for cutting the slab at different desired lengths wherein the sensors would
be able to detect the slab and measure its cutting length as per need inspite of guiding
plates located both the sides of roller table.
A still further object of the present invention directed to providing a system for sliding
of sensors for cutting the slab at different desired lengths which can be safely operated
without needing any person to go near the hot slab for sensor sliding activities which is
done outside the slab cutting area.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is thus directed to a sliding system for the
sensors for cutting the slabs at different desired lengths in continuous caster of steel
plant, comprising
a movable IR emitter and a IR receiver based sensors adapted for slab length
measurement purpose;
gripping and cutting mechanism adapted for gripping of trolley actuated based on said
sensors signals and effecting cutting of slabs to different desired lengths based on
interruption of IR signals by said moving slab.
A further aspect of the present invention is directed to said system wherein when said
moving slab comes across the line of sight of IR waves between emitter and receiver,
there is interruption of IR waves and forces receiver to change its state and actuate
said gripping mechanism of gripper of trolley for cutting slab to any desired length.
A still further aspect of the present invention is directed to said system wherein said
movable IR emitter and a IR receiver based sensors comprises
a fully automated sliding system having chain motor arrangement wherein IR sensors
are mounted on small trolley which are coupled to motors in chain and toothed wheel
arrangement wherein bidirectional motor drives the wheel , the lower part of said
chain rests on a channel and supports a IR sensor; said IR sensor continuously emits
the wave, part of which is reflected from a water cooled reflector and collected by IR
receiver; a set of LED and Phototransistor adapted to generate pulses and forward the
same to a counter circuit and after proper calibration of pulses, same is displayed in a
display circuit for measuring the length of slab.
Yet another aspect of the present invention is directed to said system wherein said
slidably movable IR emitter and a IR receiver based sensors comprises
a manually operated system having string pulley arrangement comprising the IR
emitter and receiver mounted on blocks adapted to slide over a channel, outside the
slab cutting area by means of pulleys and strings by rotating a handle, wherein on one
side of slab, a IR emitter slides by using one set of pulleys while on other side of slab
IR receiver R slides by using a different set of pulleys and two slab length indicators
(light emitting diodes ) which are attached with said sensors slide over measuring
scales to measure the slab cutting length.
A further aspect of the present invention is directed to said system wherein in said
counter a desired slab length is set by means of thumb wheel preset switch such that
once current counting of counter crosses said preset value, counter generates a signal
which controls the gripping /cutting circuits.
A still further aspect of the present invention is directed to said system wherein said
sensors can be adjusted according to slab length ranging from 5.5 m to 10.5m .
Also said system is adapted to ensure sensing of slab if the gap between two
successive slabs is 5 mm.
Importantly, said system is adapted for continuous measurement of slab length with a
resolution of 5mm.
Advantageously also, said system is adapted for sliding sensors for cutting slab lengths
with a maximum error of 0 to +20 mm.
A further aspect of the present invention is directed to said system wherein said Slab
Length Indicators slides over measuring scale facilitating quick shifting/placement of
sensor.
Also said system comprises guiding channels adapted for the shifting of sensors
parallel to slab.
The various other objects and advantages of the present invention are described in
greater details with reference to the following accompanying non limiting illustrative
drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1: is the schematic illustration of the conventional slab cutting system for
obtaining desired variable cut lengths of slabs in continuous caster.
Figure 2: is the schematic illustration of the slab length measurement for gas cutting of
different lengths of slabs in continuous caster involving chain-sprocket with drive motor
arrangement according to an embodiment of the present invention.
Figure 3: is the schematic illustration of the slab length measurement for gas cutting of
different slab lengths in continuous caster involving string and pulley arrangement
according to another embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING FIGURES
The present invention is directed to providing a system for sliding of sensors for cutting
the slab at different desired lengths with a maximum error of 0 to +20 mm in
continuous casting of steel plant.
Reference is first invited to the accompanying Figure 1 that illustrate the conventional
slab cutting system for obtaining desired variable cut lengths of slabs in continuous
caster. As already described The slabs are cut into different smaller base lengths
ranging from 5.5 m to 10.5 m at intervals of 30 mm by gas cutting in order to fulfill
the demand of plate Mill and other external customers. Over length slabs produce
scrap and also jam the reheating furnaces of plate mill while short length slabs reduce
the yield. Earlier the slab length was measured by using a measuring scale installed
just adjacent to roll table. As soon as front end of slab crosses desired length then
gripping/ cutting activities starts. After cutting the slab, the trolley in which gas cutting
torch is kept, returns to its initial reference rest position and get ready for next cutting
cycle. In the existing systems a number of length measuring systems such as contact
type shaft encoder, photosensor based were tried but could not cut the slab at desired
length because of slippage and decaying of roll diameter etc and needed continuous
calibration. Moreover, sparkles during cutting, influence due to variation in luminosity
of metal affected the performance of such systems. Difficulties were also found for
maintaining Laser based length measuring system, Video based dimension measuring
system.
There has been thus a need in the art to developing an automatic slab length
measuring and cutting system to ensure various slab length as per need to desired
accuracy involving sensor based measurement. The system would be capable of
working accurately even when guiding plates located on both the sides of roller table
and the line of sight between sensors and slab is hardly 5 mm available.
To achieve this a system is proposed by way of the present invention wherein a IR
emitter and a IR receiver are installed on either sides of slab. As soon as slab come
across the line of sight of IR waves, there is interruption of IR waves and forces
receiver to change its states and this phenomenon actuates gripping mechanism of
gripper of trolley. In this arrangement, for sliding the sensors for slab length
measurement purpose, two different approaches for sliding the sensor have been
carried out viz.
1. Chain motor arrangement
2. Rope pulley arrangement
1. Chain motor arrangement : For fully automated sliding system, the IR sensors
are mounted on small trolley which are coupled with respective two 0.5 KW DC
motors with chain and toothed wheel drive arrangement as shown in accompanying
Figure 2 . Wl and W2 are sprocket wheel of bicycles and are coupled with chain
while bidirectional motor M drives the wheel . The lower part of chain rests on
channel and it supports a IR sensor. The IR sensor continuously emits the wave
and part of its reflected from water cooled reflector Rl and collected by IR receiver.
A set of LED and Phototransistor generates pulses and sends them to counter
circuit. After proper calibration of pulses, same is displayed in display circuit for
measuring the length of slab. In counter a desired slab length is set by means of
thumb wheel preset switch. Once current counting of counter crosses the preset
value, counter generates a signal which controls the gripping /cutting circuits.
2. String pulley arrangement : In this arrangement, the IR emitter and receiver
are mounted on small blocks and they slide over a channel. Since slab length
cutting area is quite congested and it is unsafe for a person to go near the hot slab
therefore sensor sliding activities is done outside the slab cutting area by means of
pulleys and strings. A handle for rotating the string pulley is provided on each side
of slab which can be rotated manually to set the sensors at a particular length of
slab measured on respective scale. On one side of slab, a IR emitter S slides by
using pulleys A,B,C,D,E and F while on the other side of the slab, IR receiver R
slides by using pulleys A',B',C',D',E' and F'. Two slab length indicators I and I'
which are attached with sensors sliding over measuring scales M and M' as
illustrated in the accompanying Figure 3. The Slab Length Indicator sliding over
measuring scale facilitates quick Shifting/placement of sensor.
It has been observed that while the above two alternate designs for sliding the sensors
for slab length measurement can be adopted according to the present invention, the
relative merit/demerit of the options lies in the fact that string- pulley based sliding
system is easy to maintain while motor-chain based sliding system provides comfort
but is difficult to maintain and needs very fast breaking system for aligning the sensor
at proper position otherwise a lot of time is wasted for its alignment for desired slab
length cutting.
Thus by using the above system Sensors for measuring slab length can be adjusted
according to any slab length ranging between 5.5 m to 10,5m range, importantly also
the present arrangement ensures sensing of slab if the gap between two successive
slabs is small. The resolution of measurement by sensor sliding system is 5 mm in slab
length measurement implemented in continuous measurement. The chain motor
arrangement enable the sensor sliding system to work without cooling while in the
string pulley arrangement, a handle is simply operated to slide the sensors on two
guiding channels ensuring the shifting of sensor parallel to slab.
It is thus possible by way of the present invention to providing a system for sliding of
sensors for cutting the slab at different desired lengths with a maximum error of 0 to
+20 mm in continuous casting of steel plant. The system is simple yet reliable to
position the sensors to exact length of slabs to be cut to any slab length ranging
between 5.5 m to 10.5m range with desired precision, unaffected by factors like
slippage, decaying of roll diameter ,sparkles during cutting, influence due to variation
in luminosity of metal etc.
We Claim:
1. A sliding system for the sensors for cutting the slabs at different desired lengths in
continuous caster of steel plant, comprising
a movable IR emitter and a IR receiver based sensors adapted for slab length
measurement purpose;
gripping and cutting mechanism adapted for gripping of trolley actuated based on said
sensors signals and effecting cutting of slabs to different desired lengths based on
interruption of IR signals by said moving slab.
2. A system as claimed in claim 1 wherein when said moving slab comes across the
line of sight of IR waves between emitter and receiver, there is interruption of IR
waves and forces receiver to change its state and actuate said gripping mechanism of
gripper of trolley for cutting slab to any desired length.
3. A system as claimed in anyone of claims 1 or 2, wherein said movable IR emitter
and a IR receiver based sensors comprises
a fully automated sliding system having chain motor arrangement wherein IR sensors
are mounted on small trolley which are coupled to motors in chain and toothed wheel
arrangement wherein bidirectional motor drives the wheel , the lower part of said
chain rests on a channel and supports a IR sensor; said IR sensor continuously emits
the wave, part of which is reflected from a water cooled reflector and collected by IR
receiver; a set of LED and Phototransistor adapted to generate pulses and forward the
same to a counter circuit and after proper calibration of pulses, same is displayed in a
display circuit for measuring the length of slab.
4. A system as claimed in claims 1 or 2, wherein said movable IR emitter and a IR
receiver based sensors comprises
a manually operated system having string pulley arrangement comprising the IR
emitter and receiver mounted on blocks adapted to slide over a channel, outside the
slab cutting area by means of pulleys and strings by rotating a handle, wherein on one
side of slab, a IR emitter slides by using one set of pulleys while on other side of slab
IR receiver R slides by using a different set of pulleys and two slab length indicators
are attached with said sensors slide over measuring scales to measure the slab cutting
length.
5. A system as claimed in anyone of claims 1 to 4, wherein in said counter a desired
slab length is set by means of thumb wheel preset switch such that once current
counting of counter crosses said preset value, counter generates a signal which
controls the gripping /cutting circuits.
6. A system as claimed in anyone of claims 1 to 5, wherein said sensors can be
adjusted according to slab length ranging from 5.5 m to 10.5m .
7. A system as claimed in anyone of claims 1 to 6, which is adapted to ensure sensing
of slab if the gap between two successive slabs is 5 mm.
8. A system as claimed in anyone of claims 1 to 7, which is adapted for continuous
measurement of slab length with a resolution of 5mm.
9. A system as claimed in anyone of claims 1 to 8, which is adapted for sliding sensors
for cutting slab lengths with a maximum error of 0 to +20 mm.
10. A system as claimed in anyone of claims 1 to 9, wherein said Slab Length
Indicators(light emitting diodes) slides over measuring scale facilitating quick
shifting/placement of sensor.
11. A system as claimed in anyone of claims 1 to 10, comprising guiding channels
adapted for the shifting of sensors parallel to slab so it ensure the perpendicularity
among the sensors and also with slab,

ABSTRACT

The present invention relates to a sliding system for the sensors for cutting the slab at
different desired lengths with a maximum error of 0 to +20 mm in continuous caster of
steel plant. More particularly, the present invention relates to developing a simple, low
cost but highly reliable system to adjust the sensors for measuring and effecting
cutting of the slabs at desired lengths to meet the varying base lengths requirement of
slabs for further processing. The system comprises a movable IR emitter and a IR
receiver based sensors adapted for slab length measurement, selectively disposed in
relation to moving slab on roll table with operative signal communication there
between such that on interruption of IR signals by said moving slab, a gripping and
cutting mechanism adapted for actuating gripping of trolley is actuated effecting
cutting of slabs to different desired lengths based on said sensors signals.