FIELD OF THE INVENTION
The present invention relates to a system for tracking/ measurement of dimensions/length
of rolled steel products in semi-finished and finish stages in rolling mills of steel plants and
in particular to an infrared system for tracking/measuring the dimension in semi-finished
and finished stage. More particularly, the present invention is directed to developing an
Infra Red signal sensing based system by selective involving IR transmitter/emitter and
receivers with the steel product in between, favouring the desired IR based
tracking/measuring the dimensions of moving or stationary steel products e.g.
blooms/slabs, having temperature ranging from red luminous to black cold. The IR signal
based system and method of the present invention thus providing a simple, safe, low cost
yet highly reliable means for tracking/measurement of length of steel products even in
presence of other light/radiation sources e.g. spark, oxy-acetylene flames etc. in the vicinity
of the system where operating. The IR signal sensing based system according to the present
invention is adapted for a range of operation with pre determined transmitter to receiver
distance such that precise tracking/measurement of length of products having as low as
10mm gap between two successive blooms/billets with a least count of 25mm can be
attained with reliability and can be further adjusted by inserting additional sensors and the
system is adapted to operate up to an ambient temperature of 80°C without needing cooling
of the IR diode/LED. The IR signal sensing based tracking/measuring system and method
of the invention is thus having prospect of wide industrial application in steel plants in semi-
finished and finished stage of bloom/billet production, for online tracking/measuring of steel
products without human intervention in a safe, simple, reliable and cost effective manner,
not affected by surrounding luminous signals or adverse shop conditions including heat,
dust, fumes etc.
BACKGROUND ART
It is well known in the art of production of steel sections such as the blooms and billets, the
hot saw/flame cutting determines the section length to desired accuracy and thus influence
wastes, yield and productivity vis-a-vis the cost of products. A number of attempts have
been made in the past to ensure cutting of steel sections coming out from continuous caster
or after subsequent semi-finished or finished stage of rolling to incorporate non contact type
control of accurate cutting length to desired accuracy involving sensors and related control
electronics. The problem of short or over size length of sections for deciding the cutting
length by sensing the bloom/billet conventionally by such methods as (a) hanging chain; (b)
Photosensor; (c) Laser sensors;
Hanging chain system and method has been implemented in the existing art, wherein bloom
was measured by using contact type system i.e. a meter long metallic rod hangs over bloom
at desired distance from the initial rest position of gas cutting torch trolley. Because of poor
electrical contact due to deposition of electrically insulated carbon particles, sometimes
electrical contact does not work for electrical circuit to be on for the saw and it leads to
generate problems of over length bloom. During continuous casting of billets/blooms, if
contact based system does not work then casting has to be stopped for its rectification. Also
in such systems, if gap between two successive bloom is less than 0.6 m, then due to
pendulum phenomenon of rod, it touches the bloom much early activating the electrical
control circuit for the hot shear drive and generates under size bloom.
In photo-sensor based control of length of cast steel products, such as the bloom or billet of
steel metal specially in rolling mill/continuous casting undergoes wide variation in
temperature and sometimes such products remain enveloped with scale/powder coats,
necessitating the non contact method of light interruption is used wherein light intensity of
emitter is kept higher than the luminosity of hot metal. When the metal becomes so
luminous such that the luminosity crosses the luminosity of its sensor's emitter, thereby
emitter-receiver system fail to work satisfactorily. Photosensors (Luminous sensor) are also
affected by welding spark, gas cutting flame and background illumination. A strategy is
developed for sensing the bloom/slabs/billets/plates that undergoes a wide variation in
temperature at cutting stage. There has therefore, been a need in the art to developing a
method other than light interruption to sense the product lengths more accurately free of
adverse influence by the surrounding undesired light sources/objects.
LASER based systems suffers not only from prohibitive cost intensive infrastructure and
skilled manpower to ensure accuracy in sensing/measurement but also make it difficult to
maintain the system in the shop floor environment.
There has therefore been a need in the art to developing a non contact sensor based
tracking/measuring system for the steel products in semi-finished and finished stage that
would favour accurate and reliable measurement of length of products to desired accuracy
in a simple, safe and cost effective manner and would overcome the limitations experienced
in the prior art systems and methods. The present invention thus attempts to solve the prior
art problems by developing a low cost reliable system involving IR sensing signal based
tracking/measuring system for accurate cutting length determination in a non contact
multiple interruption method unaffected with adverse work environment like heat, dust,
fume, humidity etc. and eliminating problems due to presence of luminous objects in the
measurement site. The IR signal based sensing would favor hygienic work atmosphere
without causing any eye injury to persons working at the shop floor close to the emitter. In
industry light signals from various sources other than the target object adversely affects the
opto sensory receiver. Therefore infra red sensor is preferred while ultra violet emitter
produces signal of lower wavelengths and is also harmful for living things. Advantageously,
IR Infra red LED and photo detectors are fast acting devices, and the effective range of an
IR beam system is determined by peak current fed into transmitting LED, rather than by its
mean LED current. A system has been developed for sensing the bloom / slabs / billets/
plates that undergoes a wide variation in temperature at cutting stage, wherein a method of
other than light interruption and preferably IR signal is used,to sense.
The process of the invention favour easy installation and maintenance with display and
control at pulpit with minimum human intervention for desired precisely controlled cutting of
lengths of steel products of varied temperatures, reducing wastes and improving
productivity.
OBJECTS OF THE INVENTION
It is thus the basic object of the present invention to develop an IR signal sensing based
tracking/measuring system for determining the position/cutting length of steel products e.g.
blooms or billets in the semi-finished, finished stage with desired accuracy and reliability
using a non contact multiple interruption method, for a wide temperature range of stock
from red hot to black cold metal.
A further object of the present invention is directed to developing said IR signal sensing
based non contact tracking/measuring system for steel products in the continuous caster of
bloom/billets by selective deployment of a LED based IR transmitter adapted to generate
signals for desired length determination by multiple interruption method using a plurality of
receivers selectively spaced located at opposite side to the steel product.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein presence of other luminous objects
do not affect the performance of the system.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein the IR signals are safe for persons
working in the area and thus providing safe work environment.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein the emitter/transmitter is selectively
disposed in relation to the initial position of the gas cutting torch on trolley or hot-saw for
cutting.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein the system work on a sampling
principle.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein the measuring accuracy is
determined by the speed of travel of the steel product and the intermittent IR pulse
duration at fixed intervals.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein the On/Off timing of the IR pulse
generator from a LED based source is so selected that the problem of IR source heating and
allied measurement/sensing error due to overheating and performance degradation is
avoided.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein a stable pulse is generated to achieve
a stable IR pulse from IR diode with possibilities of controlling the on-off time period by
variable resistance.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein the system is adapted to work
satisfactorily even with a gap as low as 10mm between two successive blooms.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein the length can be corrected based on
feedback signal regarding trolley position.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein the least count of measurement of
cutting length can be about 25 mm and which can be adjusted by inserting additional
sensors in close spacing.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein the IR signal sensors can be either IR
interruptive sensors-single or multiple- having 10m range or IR Reflective sensor having up
to 4m range.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein the range of the signal can be
adjusted by feeding commensurate current in IR diode.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein the sensors are adapted to be rotated
in horizontal and vertical planes to suit the site-condition/tracking or measurement of target
object.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein a pilot light is used for focussing of
the receiver/sensor.
A still further object of the present invention directed to said IR signal sensing based
tracking/measuring system for steel products wherein said system is adapted to deliver
satisfactory performance without cooling up to 80°C ambient temperature and fan or water
cooling is used to achieve satisfactory performance for ambient temperature exceeding
80°C.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided an infrared
system for tracking/measuring the dimension of steel products in semi finished and finished
stage comprising:
IR emitter means ;
IR receiver means ;
said emitter and receiver means suitably disposed and adapted such as to facilitate the
bloom/slab measurement involving IR interruptions.
Another aspect of the present invention is directed to said Infrared system for
tracking/measuring comprising combinations of single IR Emitter and single or multiple IR
sensor receivers including IR interruptive sensors preferably single channel 10 m range and
six channel 10 m range with single emitter and multiple receiver and IR reflective sensor
preferably selected from 4m range,20 mm apart,2.5m range,2.5m apart and 2.5m range, 6
channel.
A further aspect of the present invention is directed to an Infrared system for
tracking/measuring comprising means adapted such that the pulse burst interval can be
adjusted according to tolerance of product including slab/bloom cut at desired length.
A still further aspect of the present invention is directed to said Infrared system for
tracking/measuring comprising means for adjusting the range by feeding current in IR diode
and said sensor adapted to be rotated in all three direction, piloting light to pinpoint
focusing.
A still further aspect of the present invention is directed to Infrared system for
tracking/measuring comprising
IR transmitter selectively installed from initial rest position of gas cutting torch with IR
receiver with a defined gap on other side of bloom / slab;
an LED based length display unit placed in pulpit ,below each LED number indicating the
distance is mentioned such that as soon as front end of bloom /slab cross before
respective IR receiver, the IR waves are blocked and corresponding LED glows;
plurality of control switches are mounted on operator control desk in order to adjust
bloom/slab cut length; and
another set of IR emitter and receiver provided for knowing the zero position of trolley
(gas cutting flame) and current position of trolley at rest position being displayed by
means of LED.
According to yet another aspect of the present invention is directed to said Infrared system
for tracking/measuring comprising:
adapted to work on sampling principle whereby the practical IR beam system need not
to be turned ON continuously but only needs to be turned on for short duration at
selective repletion period with the sample period being less than 200 ms but greater
than period of tone frequency;
said LED adapted to operate selectively to avoid over heating and at fixed interval a burst
preferably about 200 % of peak current is able to drive the IR diode to generate IR pulse
including means to generate a stable pulse with on-off period being controlled by Variable
resistance.
A still further aspect of the present invention is directed to said Infrared system for
tracking/measuring comprising:
means for controlling the ON period of LED ;
two sections of a CMOS quad two input NAND gate IC adapted to work in non symmetrical a
stable multi vibrator producing 1ms and 200ms periods while another is buffered and
adapted to gate a 20KHz 555 a stable output via diode and the output of 555 a stable is
then inverted via another CMOS feeding to transmitter output.
An yet further aspect of the present invention is directed to Infrared system for
tracking/measuring comprising:
tone amplifier in which infra red sensor is series with resistor is adapted such as to detect
IR signal develops voltage across it, means for amplifying this signal, the output of Infra
red receiver amplifier circuit being fed to Code Wave form detector circuit of tone
waveforms converted into DC via suitable network and fed to non inverting input of Op
amp comparator while inverting input is connected to reference voltage, the op-amp output
being high (at almost full positive ) when a selective tone input signal is present, and low
when a tone input signal is absent; if the input signal is derived from a tone-burst system,
the output follows the pulse modulation envelope of the original transmitter signal.
A still further aspect of the present invention is directed to said Infrared system for
tracking/measuring wherein the detector output is adapted to activate a relay in the
absence of a beam signal by using the expander / output driver circuit.
A still further aspect of the present invention directed to said Infrared system for
tracking/measuring wherein the same is adapted to provide DC output voltage that in time
expanded version of input voltage which output voltage is buffered and inverted and used to
activate the relays and gate means and adapted such that the relay is off when the beam is
present but is driven on when the beam is absent fro more than 100ms or so except when
the relay is conditionally effectively disabled.
A still further aspect of the present invention is directed to said Infrared system for
tracking/measuring comprising diodes selectively located preferably at 50 mm interval and
at 5.3 m, 5.35m, 5.4m, 5.45 m, 5.5m and 5.55m respectively from the gas cutting torch
while it is at rest initial position, said length can be selected by selector switches installed on
length display unit installed in pulpit, the signal thus received from selected I R diode is
processed through Infra red receiver amplifier, Code Wave form Detector, Expander /
Output Driver and finally actuates the relay RL.
A still further aspect of the present invention is directed to infrared system for
tracking/measuring comprising means for audio and/or visual indication at anyone or more
of relay o/p, opto coupler and OC Tr for indicating product bloom/slab crossing desired
length.
A still further aspect of the present invention is directed to said Infrared system for
tracking/measuring comprising means adapted for correcting the length based on feedback
of the trolley positions.
A still further aspect of the present invention is directed to said Infrared system for
tracking/measuring comprising selectively:
means to insert sensors for adjusting least count of 25mm;
sensor adapted to be rotated in horizontal and vertical planes to suit site conditions;
external cooling means preferably selected from micro fan, water cooling jacket in case of
cooling beyond 80°C;and
pilot light adapted to focus the receiver for focussing.
The present invention and its objects and advantages are described in greater details with
reference to the accompanying non limiting illustrative embodiments and figures.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: is the illustration of the comparative spectral range for the optical and IR based
signals for visible and the invisible light emitting LED based source/transmitter for desired
tracking/measuring of dimension of steel products.
Figure 2: is the schematic illustration of the IR transmitter and receiver based system of the
present invention shown with a simple block diagram for the IR code waveform based object
detection system.
Figure 3: is the schematic illustration of the single channel based transmitter and receiver
system for IR signal interruptive sensor based tracking/measuring of dimensions according
to an embodiment of the invention.
Figure 4: is the schematic illustration of the six channel based IR interruptive sensor based
system for precise tracking measuring of the steel products according to another preferred
embodiment of the present invention.
Figure 5: is the schematic illustration of the IR reflective sensor based object detection
system using reflection of coded waveforms from the IR transmitter and detection by the IR
receiver over 4m range and located 20mm apart.
Figure 6: is the schematic illustration of the working of single channel IR reflective sensor
according to the invention.
Figure 7: is the schematic illustration of the working of six channel IR Reflective Sensor
based object detection/measuring system of the invention applicable for over 2.5 m range.
Figure 8: is the schematic illustration of the IR Reflective sensor comprising the transmitter
and receiver adapted to rotate in horizontal and vertical plane for desired object detection
or for tracking/measuring of steel products by reflection method over 2.5m range and
located 2.5 m apart.
Figure 8(a): is the schematic illustration of an embodiment of focussing arrangement of IR
emitter/receiver according to the present invention to avoid effect of light
sources/reflections from surrounding for desired object detection or for tracking/measuring
of steel products.
Figure 9: is the schematic illustration of the circuit diagram for control of the ON and OFF
timing of the IR emitter for 1ms burst 20KHz pulse by selective use of capacitor and
resistors for said On and Off timings.
Figure 10: is the schematic illustration of circuit diagram for the IR receiver according to an
embodiment of the present invention comprising six IR diode selectively spaced apart for
interruptive signals based tracking/measuring of dimension/cutting length of steel product.
Figure 11: is the bloom length display and control unit adapted to display the lengths of
different steel products length being cut by saw/gas cutting on trolley corresponding to
eight initialised trolley position, for visual display at pulpit and control of switching at
operator's desk at pulpit.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING DRAWINGS
The present invention relates to IR signal sensing based system for tracking/measuring
dimension of steel products e.g. blooms/slab/billets, in the semi-finished and finished stages
of the continuous caster plant or rolling mills. The system and non contact method for
automatic determination of cutting length of the steel products using IR interruptive and or
reflective principle favour attaining desired accuracy of dimension minimizing the under or
over sized lengths thus reducing wastes and improving output and productivity. The system
performs safely satisfactorily up to 80°C ambient without need for any cooling for longer
operating life with minimum down time. The present invention thus apply and use the IR
interruption based signal sensing system for the first time with distinct advantage over the
prior art systems and methods, for on-line measurement of bloom/slab length and its
control for cutting operation.
Reference is first invented to the accompanying Figure 1 that illustrates the comparative
spectral range for the optical and IR based signals for visible and the invisible light emitting
LED based source/transmitter for desired tracking/measuring of dimension of steel products
utilized by the system of the invention. As already described, infra red sensor is preferred
while ultra violet emitter produces signal of lower wavelengths and is also harmful for
persons working at shop floor things. Advantageously, IR Infra red LED and photo detectors
are fast acting devices, and the effective range of an IR beam system is determined by peak
current fed into transmitting LED, rather than by its mean LED current, and free of any
injurious effect on operators/persons at site. IR based sensing is further remain unaffected
without sacrificing its inherently designed accuracy and tolerance of measurement, by any
visible light source e.g. spark, gas cutting flame etc. located in the vicinity of the
measurement sight and also not influenced by presence of dust, fume, heat etc in the
surrounding work area. The process of the invention favour easy installation and
maintenance with display and control from pulpit for desired precisely controlled cutting of
lengths of steel products reducing wastes and improving productivity.
It is worth mentioning here that human eye is sensitive to a range of light radiation as
shown in Figure 1; It has a peak spectral response to the colour green, which has a wave
length of about 550 nm, but has a relatively low sensitive to the colour violet (400 nm) at
one end of the spectrum and to dark red (700 nm) at the other end . Photodiodes also have
spectral response characteristics, and these are determined by the chemistry used in the
semiconductor junction material.
The characteristics of alloy of high intensity GaAIAr helps generating pulse in Infrared (IR)
region and its peak emission response is at 940 nm. IR LED is used to transmit coded
invisible light signal, which is detected by a matching IR diode and subsequently decoded in
a receiver system some distance away.
Reference is now invited to the accompanying Figure 2 that schematically illustrates the IR
transmitter and receiver based system of the present invention shown with a simple block
diagram for the IR code waveform generation and sensing based 'object detection system'.
The system basically providing an IR transmitter generating square waveform (coded
waveform and is directed /focussed on to a IR transmitter for receiving and transforming
into the code waveform detector at out put for detection of a target object.
Reference is now invited to the accompanying Figure 3 that schematically illustrate the
working of the single channel based transmitter and receiver system for IR signal
interruptive sensor based tracking/measuring of dimensions according to an embodiment of
the invention. This is a simple embodiment to illustrate the principle of interruption method
for detection of object by IR emitter and receiver placed on either side of the product.
Reference is now invited to the accompanying Figure 4 that schematically illustrate the six
channel interruptive IR signal sensor based system according to another preferred
embodiment of the present invention, for precise tracking/measuring of the steel products
in continuous caster plant or rolling mill finishing stage to ascertain desired cutting length
within acceptable tolerance limit.
According to a preferred embodiment of the system of online tracking and non contact
measurement of the moving/static product lengths using IR signal sensing based system
installed at the continuous caster plant in one of the large integrated steel plants of the
applicants. The installed system comprised one IR transmitter of 10 m range used to send
signals to six numbers IR receivers at a distance of 10m from emitter and are located
50mm apart. The pulse burst interval from the LED based IR transmitter is adjusted
according to tolerance of product i.e. to cut slab/bloom at desired length operatively by hot
saw or gas cutting torch mounted on trolley. Such an embodiment used multisensor
receivers configuration with the single IR emitter, wherein the signal generated is not
affected by the luminous signals or noise in the surroundings such as spark, gas cutting
flame etc. the range can be adjusted by feeding the peak current in the IR diode. The
sensors are so mounted that they can be rotated in all three co-ordinate directions in order
to facilitate pointing at the target object. The system is adapted to operate reliably and
safely upto an ambient temperature of 80°C without cooling. A pilot light is used to pinpoint
focusing on the sensor in relation to the emitter. The system further allow safe
workmanship practice as the IR signal wave do not harm vision of human eye.
A IR Transmitter is installed at a distance of 5.4 m from initial rest position of gas cutting
torch while 6 numbers IR Receiver with a gap of 50 mm are put on other side of the
slab/bloom A corresponding LED based length display unit is placed in the pulpit such that
available alternate lengths are marked below each of six LEDs e.g. lengths of 5.300m,
5.350m, 5.40m, 5.50m are marked below LED numbers 1 to 6, placed in the pulpit for
view/notice by the operator. As soon as the front end of one slab/bloom cross a respective
IR first receiver in a row of six, the IR waves are blocked and corresponding LED glows in
pulpit. The operator has six numbers of control switches located at the operator's control
desk at pulpit, which is then selectively operated by the operator to selectively adjust and
ascertain the cutting length according to requirement to cut the bloom/slab by operating
trolley mounted saw/gas cutting torch.
A separate set of IR emitter and corresponding 8 receiver channels are used for knowing the
zero position of trolley with gas-cutter torch/saw and the current position of tolley at rest
position which are also displayed by LED lamps the same way as of the cutting lengths of
blooms, inside the pulpit.
Importantly, the IR interruptive sensing based system of the invention works on sampling
principle wherein the pulse duration and frequency is based on the caster speed and
measuring accuracy required. As for example, with the normal casting speed of bloom
0.6m/min or 10mm/sec, a bloom takes lsec to move through 10mm. Maximum speed of
bloom may be 50mm/sec. So to ascertain a measuring error of 10mm, the bloom takes
200ms to cross this 10mm distance. Accordingly, the IR beam need not be turned on
continuously but only needs to be turned on for a short while at repletion period of 200ms.
The sample period should be less than 200ms but greater than period of tone frequency.
Another aspect of reliable working of the IR signal based tracking and measuring system is
the control of heat generation of IR LED emitter. The LED heats up at a rate faster than the
rate at which it cools down. Thus the pulse on time and the pulse off time need to controlled
to restrain the heat generation. It has been experimentally established that an ON time of
25µs and OFF time of 25 ms serve the purpose satisfactorily upto an ambient temperature
of 80°C without cooling. And need not be operated continuous mode. To generate a burst IR
pulse at fixed intervals, the IR diode to is driven with 200% of peak current. A stable pulse
is favourably generated using IC 555 whose On-Off period is controlled by variable
resistance in the respective control circuit.
According to yet another embodiment of IR signal based tracking/measuring system, the
principle of a reflective IR sensor based system is adopted replacing the IR Interruption
based sensing. Accompanying Figure 5 shows the schematic illustration of the IR reflective
sensor based object detection system using reflection of coded waveforms from the IR
transmitter and detection by the IR receiver over 4m range and located 20mm apart. In this
type of system the signal generated and emitted from the transmitter is reflected from the
object within the range and the reflected waveform is detected by the IR receiver and thus
the location and continuous length of an object/steel product is determined.
Accompanying Figure 6 schematically illustrate working of the same IR Reflective sensing
principle based embodiment of single channel IR reflective sensor based system according
to the invention. Similarly, accompanying Figure 7 is the schematic illustration of the
working of six channel IR Reflective Sensor based object detection/measuring system of the
invention applicable for a sensing range of 2.5 m.
Reference is now invited to the accompanying Figure 8, that schematically illustrate
another preferred embodiment of the IR Reflective sensor based system of the present
invention wherein the IR transmitter and IR receiver are so mounted as adapted to rotate in
horizontal and vertical plane, in all three axis directions for desired object detection or for
tracking/measuring of steel products by reflection method over 2.5m range and located 2.5
m apart, to suit measurement at site.
Reference is now invited to the accompanying Figure 8(a), that schematically illustrate an
embodiment of an embodiment of focussing arrangement for IR emitter/receiver to avoid
effect of light sources/reflections from surrounding for desired object detection or for
tracking/measuring of steel products. The IR emitter/ Receiver in such an embodiment of
focussing arrangement with tubular housing for emitter/receiver is mounted on front portion
of a stainless steel pipe having 20 mm inner diameter and 24 mm outer diameter and a
length of about 200 mm with a transparent front cover glass to allow IR signal to and from
target. This pipe slides within a pipe having 25 mm inner diameter and a length of about
250mm, in order to suit the site conditions i.e. (a) avoiding reflection from surrounding ,(b)
getting IR reflection from rough surface of bloom /slab due to scale skin patches in order for
desired detection of length. A stud is provided on outer pipe for fixing up the emitter inside
the tube once focusing is done. The entire focusing arrangement is mounted on a stand
having tilting facility to align with target object.
Reference is now invited to the accompanying Figure 9, that schematically illustrate the
circuit diagram for control of the ON and OFF timing of the IR emitter for 1ms burst 20KHz
pulse by selective use of capacitor and resistors for adjusting said On/Off timings.
In said accompanying Figure 9, it is clearly apparent that the ON period of LED is controlled
by C2 and R2 and OFF period by C2 and (R2+R1).
Two section of 4011B CMOS quad two input NAND gate IC work in non-symmetrical a stable
multi vibrator producing 1ms and 200 ms periods, another 4011B is buffered and used to
gate a 20 KHz 555 a stable via diode D2 and the output of IC 555 a stable is then inverted
via a fourth 4011 B and feeds to transmitter output. The value of R4 can be given as low as
2.2 ohms to give peak output currents of 550 mA, but that under this condition the
transmitter consume a mean current of 6 mA.
The accompanying Figure 9 shows that the 20 KHz tone amplifier in which infra-red sensor
is in series with R1 so that detected IR signal develops voltage across it. This signal is
amplified by CA3140. The output of Infra red receiver amplifier circuit is fed to Code Wave
form detector circuit of 20KHz tone waveforms are converted into DC via the C1-D1-D2-C2-
R5-C3 network and fed to non inverting input of Op-amp comparator while inverting input is
connected to reference voltage. The op-amp output is high (at almost full positive) when a
20 KHz tone input signal is present, and low when a tone input signal is absent; if the input
signal is derived from a tone-burst system, the output follows the pulse modulation
envelope of the original transmitter signal. The detector output can be made to activate a
relay in the absence of a beam signal by using the expander / output driver circuit.
When the input signal from the detector circuit switches high C1 changes rapidly via D1, but
when the input switches low C1 discharges slowly via R1 and RV1, C1 thus provides a DC
output voltage that is time expanded version (with expansion pre-settable via RV1) of input
voltage. This DC output voltage is buffered and inverted via IC 1 and used to activate relay
RLA via Q1 and AND gate made by using 2 NAND gates. Normally, the other (pin 2) input
of this AND gate is biased via R2, and the circuit action is such that when used in a
complete IR light-beam system, the relay is off when the beam is present, but is driven on
when the beam is absent for more than 100 ms or so. This action does not occur, however
when 2 of the AND gate is pulled low, under this condition the relay is effectively disabled.
The purpose of the R2-C2 network is to automatically disable the relay network via the AND
gate for several seconds after power is initially connected to the circuit or after DISABLE
switch S1 is briefly operated.
Reference is now invited to the accompanying Figure 10, that's schematically illustrate the
IR receiver according to an embodiment of the present invention comprising six IR diode
selectively spaced apart for interruptive transmitted signal for desired tracking/measuring of
dimension/cutting length of steel product. The Figure 10 shows 6 I R diode (1I 12 I3 I4
15 16 ) are located at 50 mm interval and they are located at 5.3 m, 5.35m, 5.4m. 5.45m,
5.5m and 5.55m respectively from the gas cutting torch a while it is at rest at initial
position. The length can be selected by selector switches installed on length display unit
installed in pulpit. The signal so received from selected I R diode is processed through Infra
red receiver amplifier, Code Wave form Detector, Expander / Output Driver and finally
actuates the relay RL and thus initiating desired cutting action of the bloom to required
length.
Reference is now invited to the accompanying Figure 11 that schematically illustrate the
display and control unit at the pulpit for switching operation to be performed by the
operator depending on desired length to be cut for any bloom/slab section. For this the zero
position as well as the initial trolley position at start of the operation is also displayed by
eight LEDs at the pulpit, to facilitate the operator to decide correct length of steel product in
relation to trolley with saw/gas cutting and effect appropriate switching operation.
It is thus possible by way of the present invention to developing a IR signal sensing based
system for tracking/measuring lengths/dimensions of steel product in the semi-finished and
finished stage of the continuous caster or rolling mill to ascertain the cutting length
automatically to the desired accuracy/tolerance for a temperature range of product from red
hot to black cold blooms. The present IR signal based system is capable of eliminating many
limitations of the prior art system. The IR signals sensing is free of any disturbance by the
presence of any other optical luminous sources at the site of the measurement. The IR
signal is also safe for persons working at shop floor as it does not cause eye injury or any
health hazards. The system and method of the invention is adapted for reliable
determination of moving/static dimensions/cutting length of steel sections in a non contact
automated online method, with minimum operators' intervention and control from pulpit
itself, in a safe reliable and cost effective manner, reducing wastage and improving
productivity.
WE CLAIM:
1. Infrared system for tracking/measuring the dimension of steel products in semi finished
and finished stage comprising:
IR emitter means ;
IR receiver means ;
said emitter and receiver means suitably disposed and adapted such as to facilitate the
bloom/slab measurement involving IR interruptions.
2. Infrared system for tracking/measuring as claimed in claim 1 comprising combinations of
single IR Emitter and single or multiple IR sensor receivers including IR interruptive
sensors preferably single channel 10 m range and six channel 10 m range with single
emitter and multiple receiver and IR reflective sensor preferably selected from 4m range,20
mm apart,2.5m range,2.5m apart and 2.5m range, 6 channel.
3.Infrared system for tracking/measuring as claimed in anyone of claims 1 or 2 comprising
means adapted such that the pulse burst interval can be adjusted according to tolerance of
product including slab/bloom cut at desired length.
4. Infrared system for tracking/measuring as claimed in anyone of claims 1 to 3 comprising
means for adjusting the range by feeding current in IR diode and said sensor adapted to be
rotated in all three direction piloting light to pinpoint focusing.
5. Infrared system for tracking/measuring as claimed in anyone of claims 1 to 4 comprising
IR transmitter selectively installed from initial rest position of gas cutting torch with IR
receiver with a defined gap on other side of bloom / slab;
an LED based length display unit placed in pulpit,below each LED number indicating the
distance is mentioned such that as soon as front end of bloom /slab cross before
respective IR receiver, the IR waves are blocked and corresponding LED glows;
plurality of control switches are mounted on operator control desk in order to adjust
bloom/slab cut length; and
another set of IR emitter and receiver provided for knowing the zero position of trolley(
gas cutting flame) and current position of trolley at rest position being display by means
of LED.
6. Infrared system for tracking/measuring as claimed in anyone of claims 1 to 5 comprising:
adapted to work on sampling principle whereby the practical IR beam system need not
to be turned ON continuously but only needs to be turned on for short duration at
selective repletion period with the sample period being less than 200 ms but greater
than period of tone frequency;
said LED adapted to operate selectively to avoid over heating and at fixed interval a burst
preferably about 200 % of peak current is able to drive the IR diode to generate IR pulse
including means to generate a stable pulse with on-off period being controlled by
Variable resistance.
7. Infrared system for tracking/measuring as claimed in anyone of claims 1 to 6 comprising:
means for controlling the ON period of LED ;
two sections of a CMOS quad two input NAND gate IC adapted to work in non symmetrical a
stable multi vibrator producing 1ms and 200ms periods while another is buffered and
adapted to gate a 20KHz 555 a stable output via diode and the output of 555 a stable is
then inverted via another CMOS feeding to transmitter output.
8. Infrared system for tracking/measuring as claimed in anyone of claims 1 to 7 comprising:
tone amplifier in which infra red sensor is series with resistor is adapted such as to detect
IR signal develops voltage across it, means for amplifying this signal, the output of Infra
red receiver amplifier circuit being fed to Code Wave form detector circuit of tone
waveforms converted into DC via suitable network and fed to non inverting input of Op
amp comparator while inverting input is connected to reference voltage, the op-amp output
being high (at almost full positive ) when a selective tone input signal is present, and low
when a tone input signal is absent; if the input signal is derived from a tone -burst system,
the output follows the pulse modulation envelope of the original transmitter signal.
9. Infrared system for tracking/measuring as claimed in claim 8 wherein the detector
output is adapted to activate a relay in the absence of a beam signal by using the expander
/ output driver circuit.
10. Infrared system for tracking/measuring as claimed in anyone of claims 1 to 9 wherein
the same is adapted to provide DC output voltage that in time expanded version of input
voltage which output voltage is buffered and inverted and used to activate the relays and
gate means and adapted such that the relay is off when the beam is present but is driven
on when the beam is absent for more than 100ms or so except when the relay is
conditionally effectively disabled.
11. Infrared system for tracking/measuring as claimed in anyone of claims 1 to 10
comprising diodes selectively located preferably at 50 mm interval and at 5.3 m, 5.35.
5.4m. 5.45 m, 5.5m and 5.55m respectively from the gas cutting torch while it is at rest
initial position, said length can be selected by selector switches installed on length display
unit installed in pulpit, the signal thus received from selected I R diode is processed
through Infra red receiver amplifier, Code Wave form Detector, Expander / Output Driver
and finally actuates the relay RL.
12. Infrared system for tracking/measuring as claimed in anyone of claims 1 to 11
comprising means for audio and/or visual indication at anyone or more of relay o/p, opto
coupler and OC Tr for indicating product bloom/slab crossing desired length.
13. Infrared system for tracking/measuring as claimed in anyone of claims 1 to 12
comprising means adapted for correcting the length based on feedback of the trolley
positions.
14. Infrared system for tracking/measuring as claimed in anyone of claims 1 to 13
comprising selectively:
means to insert sensors for adjusting least count of 25mm;
sensor adapted to be rotated in horizontal and vertical planes to suit site conditions;
external cooling means preferably selected from micro fan, water cooling jacket in case of
cooling beyond 80°C;and
pilot light adapted to focus the receiver for focussing.
15. Infrared system for tracking/measuring substantially as herein described and illustrated
with reference to the accompanying figures.

An Infra Red signal based system for tracking/ measurement of length of steel products in
semi-finished and finish stages in steel plants involving multiple signal interruption method,
achieved through selective disposition of one IR LED transmitter/emitter and a plurality of
selectively disposed interruptive/reflective receivers near the moving steel product, adapted
to tracking/measuring the dimensions blooms/slabs online in red hot luminous to black cold
condition. The IR signal sensing based system is adapted for a range of 2.5m to 10m
between the transmitter to, working in sampling mode with a time period of less than
200ms, with ON time of 25µs and OFF time 25ms and 200% of peak current sent at fixed
intervals to drive the IR diode in order to generate a burst IR pulse, such that precise
tracking/measurement of length with a least count of 25mm is achieved with reliability and
is adjusted by inserting additional sensors. The system operates reliably up to 80°C without
cooling of emitter and not disturbed by any local luminous source. The display means on a
LED based unit in the pulpit allow selecting cutting desired length from operator's control
desk.