FIELD OF INVENTION
The present invention relates a system for measuring on-the-
fly length of hot rolled long steel products. The invention,
particularly, relates to a system comprising sensor means and
controller means for measuring on-the-fly length of hot rolled
long steel and can advise the operator / user of the length of
the product in advance making it easier for the operator /
user to decide upon length of sample and crop length to be cut
thereby improving the yield.
BACKGROUD OF_INVENTION
Generally, rail and structural mill (RSM) produces R52 (52
kg/m) and R60 (60 kg/m) grades of rails of 13 meters, 26
meters and 78 meters. After finishing stand the rail length is
in the range of 68-87 meters, which is cut into 5 to 6 pieces
of 13.5 meter each at not saws area.
The input to the RSM is blooms from continuous casting
division (CCD). The CCD produces blooms of specific dimensions
irrespective of grade of rail ready to be rolled at RSM.
Therefore, from same bloom, 6 pieces of 13 meter R52 rail can
be finished in comparison to 5 pieces of R60 rail of similar
length.
Since the blooms used at RSM reheat furnace are likely to be
produced at different point of time in CCD, the exact
dimension of the bloom may vary based on many conditions such
as mold wear, cutting machine lag and control system
performance. This little variation in dimension gets magnified
in final length by 2-3 meters of 60 meters approximately.
In R60 grade, minimum length of rail after finishing stand is
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5 x 13.5 (inter saw distance) + 1 meter (front and tail crop)
= 68.5 meters
indicating that any rail out of finishing stand less than 68.5
meters cannot be cut into 5 pieces. But it also implies that
the excess length beyond 63.5 meters can be cut as sample for
mechanical properties and other testing.
The disadvantage is that if a sample of 1.5 meter is cut from
total length of 69.5 meters then 69 meters of the total length
is left which can produce 4 rails instead of 5 rail which is a
massive loss of grade processed steel.
The available technologies for length measurement includes
pinch roll-shaft encoder combination, laser based systems
working on doppler's principle of frequency shift due to
velocity.
In the pinch roll-shaft encoder combination, the shaft encoder
is mounted on a pinch roll assembly which touches the surface
of object of interest and cannot be used due to contact and
friction problems.
In the laser based system length is obtained from velocity
integrated over time. These systems are highly accurate but
quite costly. Variation in line of travel on roll table will
affect the accuracy significantly.
In noise of the existing technologies contact less system, for
measuring on-the-fly length of hot rolled long steel product
(herein steel bar) advising possibilities of total length in
advance has been found.
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The present inventors have surprisingly found that a system,
incorporated with sensor means and controller means located in
at predetermined distance from the object of which the length
is to measured, provides possible lengths of the object in
advance. By this the operator / user would be able to decide
upon the length or the sample and crop length to be cut to
improve production yield.
OBJECTS OF INVENTION
Thus one object of the present invention is to provide a
system for measuring on-the-fly length of hot rolled long
steel bar.
Another object of the present invention is to provide sensor
means to advice possible length measurement of the steel bar
in advance.
Yet another object of the present invention is to pravide non-
contact type length measurement system thereby preventing
friction with the surface of the bar.
Yet another object of the present invention is to provide
controller means with high time resolution.
The other object of the present invention to provide length
measurement accuracy of ± 50 mm.
SUMMARY OF INVENTION
Thus according to the basic aspect of the present invention
there, is provided a system for measuring length of hot rolled
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object so as to provide an advanced knowledge of possible
lengths of the object, said system comprising :
(i) sensor means being placed at predetermined distance
from the object; and
(ii) controller means in operative connection with said
sensor means so as to receive any actuating signal
from the sensor means.
DETAILED DESCRIPTION_OF_INVENTION
In the present invention the system for measurement of length
of hot rolled object comprises sensor means which is in
operative connection with a controller means.
In an embodiment of the present invention the sensor means
comprises, hot metal detectors to detect presence or absence of
hot infra-red emitting material with infra-red radiation
between -650ºC and 1150°C. The hot metal detector are present
five in number and each provided with focusing means and main
unit / testing means. The focusing means comprises sensor head
with lens located near the object approximately 0.5 meters
from the object and is placed in the line of sight so as to
focus properly on the object. The main unit / testing means is
a pre-amplification-cum-test-cum-output unit having different
types of output such as open collector output, relay output,
etc. for further use.
In another embodiment of the present invention, the controller
means of the system comprises internal clock/timer programmed
to have resolution of 10 milli-second (msec). The controller
means also comprises at least a processor, an input card and an
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output card wherein the processor being designed such that it
could accept input from input card and send output
corresponding to the receive input signal to the output card.
Yet in another embodiment the hot metal detector track the
movement of the object and as soon as it detects presence of
hot object in front of its sensor head it sends signal to the
main unit which in turn sends signal to the controller. The
controller based on its inbuilt logic start or stop the
timer (s) and on exit of the object the controller calculate
length based on values accumulated within the timer.
In the method of the present, invention positive edge
transition i.e. arrival of a new metal is detected by sensor
(herein denoted by S1). All flags and calculated values are
reset. Then T12 , T13 , T14 , Tl5 , T23 , T34 , and T45 till 51
remains high, wherein
T12 = Time duration during which sensors S1 and S2 are ON
simultaneously;
T13 = Time duration during which sensors S1 and S3 are ON
simultaneously;
T14 = Time duration during which sensors S1 and S4 are ON
simultaneously;
T15 = Time duration, during which, sensors S1 and S5 are ON
simultaneously;
T23 = Time duration during which metal is between sensors S2
and S3;
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T34 = Time duration during which metal is between sensors S3
and S4;
T45 = Time duration during which metal is between sensors S4
and S5;
The length is calculated based first non-zero value available
in memory location in the order of T15 , T14 , T12 and' T12 . then
the segmented velocity is measured by
Vx,x+1 = Dx,x+1/Tx,x+1
Where Dx, x+1 is the length of the segment between x and x+1.
Variable distance VD1x = (T1x) x (Vx, x+1) . In the present
invention for V15 , V45 is used since there is no S6.
Thus total length is determined as (D1x + VD1x),
In the method of the present invention fixed length is taken
to be the distance between two farthest sensors glowing
simultaneously, one being S1 . For example the distance is
68.5 meters. Variable length time duration equivalent, to
excess length beyond. S1 is provided by a timer T1 and the time
duration required by the bar/metal to travel distance between
S1 and S2 i.e. 0.5 meter is provided by timer T2.
Therefore, velocity = 0.5 meter / T2 millisecond
Variable length = Velocity x Tl
Total Length = Fixed Length + variable length.
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Distance segment considered for velocity measurement is same
under which the final length will fall i.e, S2-S3 for 68.5-
69.u meters range, S3-S4 for 69.0-69.5 meters range, S4-S5 for
69-5-70.0 meters range.
BRIEF DESCRIPTION OF ACCOMPANYING FIGURES
Figure 1 illustrates length measurement system of the present,
invention.
Figure 2 illustrates length measurement system with the
distance segments of the bar.
DETAILED DESCRIPTION OF ACCOMPANYING FIGURES
In the figure length measurement system of the present
invention is illustrated. Hot metal detectors (1, 2, 3, 4 and
5) comprises of main units (MU), MU2, MU3, MU4 and MU5) and
sensor heads (S1, S2, S3, S4 and S5) placed at a distance of
0.5 meter from the object / bar (6) (also realizable from
figure 2). The controller means (7) comprises of digital input
card (8), processor (9) and output card (10) which is
imperatively linked to display unit which is a 4 digit panel
meter (11) . Sensor head (S1) is placed, at a distance of 2
meters from the finishing stand (12).
The invention has been described in a preferred form only and
many variations may be made in the invention which will still
be comprised within its spirit. The invention is not limited
to the details cited above. For example, different lengths of
the object, distance of the sensor head from the object may be
used and still the invention can be performed.
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WE CLAIM
1. A system for measuring length of hot rolled object so as
to provide an advanced knowledge of possible lengths of
the object, said system comprising ;
(i) sensor means being placed at predetermined
distance from the object; and
(ii) controller means in operative connection
with said sensor means so as to receive any
actuating signal from the sensor means.
2. System as claimed in claim 1, wherein the sensor means
comprises hot metal detector units so as to detect
presence or absence of hot infra-red emitting material
with infra-red radiation.
3. System as claimed in claim 2; wherein the infra-red
radiation temperature ranges from 65.0°C to 1150°C.
4. System as claimed in any one of preceding claims, wherein
the hot metal detector comprises :
(i) focusing means having sensor heads with lens located
at a predetermined distance from the object; and
(ii) testing means in operative connection with the
sensor head.
5. System as claimed in claim 4, wherein the sensor heads
being placed at approximately 0.5 meters in the line of
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sight from the object so as to focus properly on the
object.
6. System as claimed in claim 4, wherein the testing means
comprises pre-amplification-cum-test-cum-output unit.
7. System as claimed in claim 1, wherein, the controller
means comprises atleast a processor, an input card, an
output card and programmed clock/timer being such that it
accepts input from input card and send output
corresponding to the receive input signal to the output
card.
8. System as claimed in claim 7, wherein, the timer comprises
time resolution of 10 milli-second so as to provide high
precision length measurement.
9. A system for measuring length of hot rolled object as
herein described and illustrated with reference to the
accompanying figures.

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The present invention relates to a system for measuring length
of hot rolled object so as to provide an advanced knowledge of
possible lengths of the object. The system comprises sensor
means (1,2,3,4,5) placed at predetermined distance from the
object; and controller means (7) in operative connection with
said sensor means (1,2,3,4,5) so as to receive any actuating
signal from the sensor means.