FIELD OF THE INVENTION
The invention generally relates to a hot metal detector with analog circuitry used
for different systems in a metal producing plant. More particularly, the invention
relates to an intelligent hot metal detector device adaptable to different systems
in a metal producing plant.
BACKGROUND OF THE INVENTION
In the prior art, systems for automatic surface inspection are well established
and used for industrial applications such as the inspection of steel. The applied
cameras [monochrome/color line scan cameras] use external illumination
[fluorescent lamps/halogen lamps/fiber optic illuminators]. The items to be
detected and classified [width/temperature] manifest themselves in different
ways, example in deviations of reflectively, glossiness, color, texture or the 3D-
profile of the surface under inspection.
The prior art system involve a camera and the illumination system. The aim is to
achieve images from the surface which contain the necessary information to
detect and to distinguish all the defects automatically, including 3D-defects. In
many cases the result is disappointing. The reason is simply that monocular
images do not contain reliable and unambiguous information. In addition these

setups suffer from a number of shortcomings: the alignment of cameras is
difficult. They have to operate in a hostile environment, where a hot steel strip is
a passing at high speed [10M/sec], and in an environment full of steam from the
cooling sprays, and the mechanical constructions for these systems become
heavy. They are also expensive.
An alternative is to use the light from the hot transfer bar itself. During hot
rolling, the transfer bar is at temperatures where it glows red hot. By arranging
an array of fibre optic cables over the moving strip, and collimating the light from
the transfer onto the tips of the fiber optical cables, it is possible to detect the
edges of the transfer bar. Hot metal detector, with analog circuitry, is known in
the art. Due to analog circuitry, all the adjustments are done manually using
potentiometer. This calls for individual tuning of all the devices and takes time.
Also any drift in potentiometer value setting over a period of time may reduce
the accuracy.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an intelligent hot
metal detector which eliminates use of potentiometer requiring manual
adjustment of the devices.
Another object of the present invention is to provide an intelligent hot metal
detector which allows automatic adjustment against drift and aging.

A further object of the present invention is to provide an intelligent hot metal
detector which adapts a microcontroller as a signal processing unit.
A still further object of the present invention is to provide an intelligent hot metal
detector which is capable of detecting level and edge detecting data including
detection of average speed of the passing hot metals.
An yet another object of the present invention is to provide an intelligent hot
metal detector which is having a reduced analog circuitry.
A still another object of the present invention is to provide an intelligent hot
metal detector which is configured to have multiple channels without increasing
the processing electronics.
SUMMARY OF THE INVENTION
The proposed system is developed adapting a microcontroller as the signal
processing unit. This eliminates the use of potentiometer for adjustment to a
large extent. Also the associated analog circuitry is reduced. Intelligence is built
for automatic adjustment against drift and aging. It is also possible to have
multiple channel (4 numbers) attached to the same unit without increasing the
processing electronics. The channels can be used either in differential mode or in
normal mode. Due to this, the overall cost of hot metal detection in a confined
area can be reduced.

The data like edge detection and multi-level detection can also be derived from
the reading of the IR generated by the hot metal. It is also possible to obtain the
speed of the passing hot metal by measuring the time difference between two
detection points. Due to the implementation of micro controller, it is now
possible to have computer interface with the hot metal detection unit.
The intelligent hot metal detector device consists of at least three features as
described below:
Light Capturing Optics:
The light capturing optics comprises a small diameter lens, which helps to focus
the incident radiation from the hot metals into a fiber optic conduit.
Fiber Optic Conduit:
A long fiber optic conduit transmit the light to a micro controller based electronic
detection means. This fiber optic conduit is connected to the end of the
capturing optics. The tip of the fiber, which is protected by a metallic closure, is
inserted completely into the capturing optics. The other end of the fiber optic
conduit is inserted into a sensor holder, which is fixed onto the side of the
electronic detection means.

Electronic detection means:
The electronic detection means converts the optical signal into electrical signal
using a silicon photo diode to detect level and edge detections. The electronic
detection means has an intelligence built in it to measure the approximate
velocity of the passing hot metal.
The electronic detection means is configured by adapting a micro controller
having silicon photo diode interfacing. This silicon diode sensor is capable of
converting the optical signal to electrical signal. The electronic detection means
consists of:
• Micro controller based electronics PCB card with power supply.
• Sensor Holder for holding the photodiode.
• Photodiode for converting the optical signal to electrical signal.
• RS 485/232 serial link for communication purpose.
• LCD display for indicating self-test, system healthy condition, other
diagnostics, speed of the hot metal and other conditions.
• 8-Key, keypad for setting up of parameters and selection of particular
display.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - shows a partial view of the device in which a plurality of optic fibre
conduits in a metallic enclosure is schematically represented.
Figure 2 - schematically shows the device of the invention.
DETAIL DESCRIPTION OF THE INVENTION
Figure - 1 shows a metallic enclosure (1) having multiple channels for disposing
a plurality of fibre optic conduit (2). Schematically shows a transfer bar (3)
including its rolling direction (4). The invented device is adapted to the rolling
mill for automatic inspection of the moving rolling of the transfer bar (3) during
rolling of steel strips.
Figure - 2 shows schematically an intelligent hot metal detector device according
to the present invention in a operating mode to detect and process data in
respect of accuracy of the moving surface of the transfer bar during rolling of
steel strips.
A plurality of light capturing optics (5) are arranged to capture and focus incident
of radiation from the hot transfer bar (3) into a corresponding number of fibre
optic conduit (6). The tips of the conduits (6) are protected by the metallic

enclosure (1). The distal ends of the fibre optic conduits (6) are disposed in a
sensor holder (7). The sensor holder (7) is fixed on an electronic detection
means (8) which is provided with at least one silicon photo diode sensor (9) for
converting the optical diode sensor (9) for converting the optical signals
transmitted via the fibre optic conduit (6) to electric signals. A RS 485/232 or
similar type of serial link (10) is interfaced to the electronic detection means (8).
A LCD means (11) is connected to the detection means (8) for indicating system
condition including diagnostics, speed of the hot transfer bar (3). A key board
(12) is operably connected for setting up of parameters and selection of display
of the particular data. The detection means (8) further comprises a
microcontroller based electronic PCB card (13) with an external power supply.
The converted electrical signals are amplified by a programmable gain amplifier
(14) before being fed to the micro controller (13). The reference value in respect
of the surfaces of the hot metal (3) is stored in a non-volatile memory in the
electronic detector means (8).
Detection Technique:
The micro controller based detection device operates on the basis of a
comparison of the background and hot metal signal by the micro controller (13).
Neither static hot scale nor steam in the field of view can cause false triggering.

Hot metal (3) is detected by the reference to data respecting to an appropriate
site adjusted control margin (stored in a non-volatile memory), which ensures
that a sufficient gap is maintained between the background IR signal and that
radiating from the product.
The electrical signal converted from the captured optical signal (using silicon
photo diode (9)) is amplified by a programmable gain amplifier (14) before it is
fed to the micro controller (13) for further processing.

WE CLAIM
1. An intelligent hot metal detector device via the sensor holder (7) comprising:
- an electronic detection means (8) having the sensor holder (7) fixed on it
and provided with at least one silicon photo diode sensor (9) for
converting the optical signals transmitted via the fiber optic conduit (6) to
electric signals;
- a micro controller based electronic PCB card (13), the micro controller of
the electronic detection means (8) comparing the background IR signals
with the on-line captured electrical signals representing incident radiation
data of the hot transfer bar (3) so that the process parameters can be
adjusted to ensure desired quality of the rolling output; and
- a LCD display (11) including a keypad (12) operably connected to the
electronic detection means (8) via a RS 485/232nserial link (10) for
displaying and controlling system conditions, speed of the hot transfer bar
(3) and associated diagnostics;
characterized in that a programmable gain amplifier (19) is provided for
amplifying the converted electrical signals received from the photodiode
(9) before the signals is fed to the microcontroller based electronic PCB
card (13).

2. The device as claimed in claim 1, wherein the tips of the fiber optic conduit (6)
are protected from heat by providing a metallic enclosure (1).
3. An intelligent hot metal detector device adaptable for automatic inspection of the
moving surfaces of a hot transfer bar during rolling of strips, as substantially
herein described with respect to the accompanying drawings.