? To get specific and reliable measuring instrument for Angle of Repose measurement.
? To get stable & reliable control of Drum feeder system in Sinter Plant.
? To avoid loss of costly Raw Mix due to spillage.
? To avoid jamming of sinter machine due to spillage of raw mix. Thereby avoiding any
production loss.
? To get better permeability of sinter bed on sinter machine for better sinter quality.
? To run the sinter machine in auto mode.
BRIEF STATEMENT OF THE INVENTION:
This instrument is direct contact type instrument to sense the change in Angle of Repose of
surface/profile of Accumulated Raw Mix fed through Drum feeder on Sinter Bed by a Mechanical
Flapper Arrangement. The change in Flapper position with the change of Angle of Repose is
sensed by a differential type capacitor & ultimately converted to 4-20 mA DC signal by EI3ctronics
for measurement and control purpose as feed back to Drum feeder control system.
Thus according to this invention there is provided an improved method of sintering a raw mix
comprising the following steps.
(a) feeding a raw mix from a hopper on to the moving bed of a sinter machine.
(b) maintaining the height or level of the moving bed constant,
(c) allowing the material to pass through a sintering furnace and discharging the
sintered material characterized by maintaining almost a constant level of the
accumulated material formed at the feeding step by means of measuring the varying
heights of the accumulated material and co-relating electronically any variation in the
height of the accumulated material with the rate of feed for the raw mix ,said
electronic correlation being achieved by arranging the lower end of a flapper to freely
rest on the surface of the accumulated material such that the flapper swings up and
down around its top end fixed to a horizontally rotating shaft held between a set of
bearings in a frame at its ends, the up and down movements of the said shaft Being

clockwise or anti -clockwise as the case may be ,and a protruding end of the rod
connected to an electronic sensor through a flexible coupling which is also
operationally connected to the drum feeder under the feeding hopper and controls
the rate of feed as per control amplitudes generated by the sensor.
Further according to this invention there is an arrangement of device for controlling the height of
accumulated material at the feed end on the sintering bed of a sintering machine for raw mix
comprising the following components.
(i) a swing able flapper adopted to have its lower end lift ably resting on the
surface of the accumulated material.
(ii) A rotatabfy rod held between a set of bearings in a frame to which rod
the said flapper's top end is rigidly held so that when the lower end of the
flapper moves up or down the said rod is rotated anti-clockwise or
clockwise as the case may be.
(iii) A flexible coupling connecting a protruding end of the rod to an electronic
circuit to develop a corrective amplitude matching of varying height of the
accumulated material and
(iv) A voltage source for the said circuit also operationally connected to the
rotating instrument and Drum feeder controller.
Still there is also provided an improved sintering machine for sintering raw mix having a feed
hopper for the mix, a drum feeder for feeding a controlled quality of the raw mix on to the endless
sinter belt of the sintering machine, a leveler or leveling the feed on the said belt, a set of roller,
namely a driving roller and a driven roller for moving the endless belt, a sintering furnace on top
of the moving belt, a power source for driving the driving roller characterized in that there is
provided a flapper plate at the feed end ahead of the leveler with its lower end to rest on the top
surface of the accumulated material on the belt.. said flapper being swingably and fixedly held at
its top to a rotatable rod, said rod being held rotatable between a set o preferably a pair of
bearings held in a frame, one end of the said rod living arranged to protrude or extend beyond the
said frame, a flexible coupling for connecting the protruding end of the said rod to an electronic
sensor having as its
BRIEF STATEMENT OF THE ACCOMPANIED DRWINGS
In the accompanied drawings:
Figure 1 schematically represents in a very very elementary way a sintering machine with the
angle repose measuring device of the invention.
Figure 2 illustrates a various stages of the functioning of the angle repose measuring device of
the invention.
Figure 3 shows a simple angle of repose measuring instrument briefly the mechanical side and
the electronic side.
Figure 4 shows the electrical/electronic side of the angle of repose measuring device.
Thus, now referring to the drawings of Figure 1, it will be clearly seen that in a simple case, the
sintering machine 'S.M.' consists of a feed hopper 1 for feeding the raw mix 2'on a conventional
sintering machine. This consists in simple language a driving roller 3 and a driven roller 4 having
the sinter machine belt 5 for convening the raw mix deposited on same. It will be seen that by
operating the dr$ ving roller 3, the belt 5 moves continuously from the feed end 6 to the discharge
end 7. A leveler 12 maintains the height. This is so as the roller 3 is driven anti-clockwise and it is
possible to have roller 4 as drive roller, roller 3 as driven roller in the anti-clockwise direction and
the top surface of the belt will travel from left to right in which case the feed hopper and furnace
8 will noticeably be at the left hand feed end. The requirement is that feed end is in close
proximity of the sintering furnace 8 so that the sintered material travels a long distance for
cooling.
It will be seen that the bottom of the hopper has a drum feeder 9, which feeds measured quantity
of the raw mix on the sintering bed at measured rate continuously.
As the material is fed the angle of repose continuously varies for various reasons such as type of
mix, feed rate, accumulated material inclination, height of bed etc. due to which there is possibility
of over spill and wastage, jamming and less production.
We have found that all these problems can be solved by suitably installing an angle of repose
measuring device correlated electronically, with the feed rate and height of the material fed on the
moving belt.
Referring to Figure^, it will be seen that angle of repose measuring device has two components,
a mechanical part 'A' and an Electronic part 'B'.
MECHANICAL PART (A)
It consists of:
11) Flapper of high Chromium Stainless Steel.
12) Rotating Rod.
13) Ball Bearings
14) Frame/Mounting Bracket.
15) Flexible Coupling.
Figure no 2 discloses details of detecting of the movements in the sintering machine in details as
follows.
In this drawing, location of Flapper 11 is shown. This Flapper 11 (light weight) is just lying on the
surface of the accumulated Material. As shown in Figure 2 the inclined surface position with
respect to horizontal Machine Bed (i.e. the angle between Bed and the surface of Accumulated
Material) is changing. Vertical height of any particular point (i.e. contact point/line of contact of
Flapper on the surface of accumulated material) or angle of repose will increase as the
accumulation of the Raw Mix increases or decreases as the accumulation decreases. This
change in accumulation occurs due to mismatch between Drum Feeder speed (i.e. feeding rate of
material) and Sinter Machine Bed Speed (i.e. withdrawn speed). As surface position changes the
Flapper rotates vertically upwards or downwards. The Flapper, which is fixed with Rotating
Rod/Shaft 12, rotates on the Ball Bearings 13 to get free rotation of flapper/rod combination. This
shaft is ultimately connected to the shaft of the Electrics Part (B)/rotation sensing sensor/Angular
position Transmitter through flexible couplings 15. Flexible couplings 15, Flexible coupling is more
suitable or force free & backlash free coupling in order to prevent backlash & axial or radial acting
bearing forces.
So the flapper just sensing the Angular position of the inclined surface of accumulated materia)
with respect to Machine Bed (i.e. angle of Repose) and this corresponds to the
accumulation of material at the location of the feeding of the material by Drum feeder.
The mechanical part is made of a steel flapper plate 11 having a suitably curved end. The outer
surface of the curvature being designed to be in contact with the inclined surface of the
accumulated raw mix at the feed end. For an idle condition the vertical angle of the plate with the
top surface of the moving belt showed be about 90°. For various reasons, there is accumulation
of the feed and thus the bed tends to expand laterally because the leveler of the sinter Machine
{Refer fig. 1 & 2) ensures a constant vertical height of the bed.
The flapper plate is mounted rigidly on a rotating shaft/ rod tj. This shaft mounted on a mounting
bracket 14 and has bearings 13 so that the rod can rotate freely urged by the rising or falling
flapper plate.
The rod / shaft 13 is coupled to the electronic component E C through a flexible coupling 15.
Thus as the level of bed changes laterally the flapper swings downwards or upwards as the case
may be.
ELECTRONIC PART (B)
1. CONSTRUCTION:-
Refer Drawing No.4
Part "B" i.e. Electronic Part basically Angular position/rotation Transmitter which generates 4 to
20 mADC signal output corresponding to Angular position of Flapper/rod combination. This
consists of encapsulated & independent Measuring Module. This Module holds one single vane
differential capacitor (i.e. rotation Sensing Sensor) & Electronic circuitry (for
conversion/processing sensor output to 4 to 20 mADC signal output) (refer drawing no A)..'.
The rotor (lug) of the differential capacitor "C" has ball bearings. The rotor«ums-betweeff turns
between the two annulus-shaped stator plates of the differential capacitor. It is connected to the
electronic circuit board in a non-contacting & wear free manner by means of a free-turning pot
capacitor. With the reaction-free measuring principle used, the angular position sensor must
overcome only the extremely low bearing friction of the differential capacitor.
The differential capacitor & the electronic circuit are surrounded by a cup-shaped metal shielding
cap. On the face of the shielding cap there are two potentiometer Pz & Ps for zero & span
adjustment & terminal blocks for connecting cable for 4 to 20 mADC signal output (two wire
system). The circuitry has radio-frequency protection, over voltage protection & electrical
isolation.
The measuring Module is built into a cylindrical case made of die-cast light metal. The shaft end
of the differential capacitors projects out of the case. This projected shaft is the shaft of Angular
position Transmitter or Electronic Part (B).
This externally projected shaft of Angular Position Transmitter/Electronics Part (B) is connected to
the sensor shaft cum the differential capacitor's shaft in the Measuring Module by means of a
force free and backlash free coupling in order to prevent backlash & axial or radial acting bearing
forces.
Casing has one no. two core cable entry for 4 to 20 mA signal output cum power supply (Two
core since this two wire system).
2. OPERATION
The angular position of Flapper of Mechanical Part (A) (this position depends on Accumulation of
Material at Feeding point) which is the measurement of Angle of Repose, is transferred by means
of mechanical coupling to the rotor of the differential capacitor (C). The capacitance of the
differential capacitor is a measure of the angular position of its rotor relative to the stator. Thei
oscillator (O) supplies a capacitative bridge circuit with a constant high frequency alternative
voltage. The output voltage of the bridge circuit rectified (r) and converted in an amplifier (a) into a
load-independent direct current ia. This output signal \3 proportional to the capacitance of the
differential capacitor and thus to the angular position of the rotor.
The zero point is roughly set by tuning the rotor with respect to the stator. Fine setting of the zero __
point as well as setting of the span is madeipotentiometer Pz & Ps respectively. tjjji
~----- ........... l .....-.....- w
The external 24 VDC power supply supplies power to constant voltage source (V) and amplifier
(a) and oscillator (0) through transformer (T). The amplifier (a) and constant voltage source (V) is
so connected that the output current of the amplifier and the constant supply current of the
constant voltage source add up. Basically output signal 4 to 20 mADC and power supply both are
using same two wire to complete the loop. Here the zero point (corresponding Vertical
position of Flapper for zero material Accumulation i.e. angle of repose =90 Deg.) corresponds to <
ia =4mA and the span point (corresponds to Horizontal position for Max. material Accumulation
i.e. angle of repose=0 Oeg) is ia =20mA. Flapper, Rotating Rod, flexible coupling and Angular
Position Transmitter all these items together forms Angle of Repose Measurement Instrument
which gives 4 to 20 mADC signal. This 4 to 20 mADC signal which gives the representation of
Flapper's Angular position (i.e. measurement of Angle of Repose i.e. feed back signal of
accumulation of Material) can be used for indication as well as feed back signal to Drum feeder
controller to control Drum feeder speed to control feeding rate.
We Claim
(1) A method of sintering a raw mix comprising the following steps.
(a) feeding a raw mix from a hopper on to the moving bed of a sinter machine.
(b) maintaining the height or level of the moving bed constant,
(c) allowing the material to pass through a sintering furnace and discharging the
sintered material characterized by maintaining almost a constant level of the
accumulated material formed at the feeding step by means of measuring the varying
heights of the accumulated material and co-relating electronically any variation in the
height of the accumulated material with the rate of feed for the raw mix .said
electronic correlation being achieved by arranging the lower end of a flapper to freely
rest on the surface of the accumulated material such that the flapper swings up and
down around its top end fixed to a horizontally rotating shaft held between a set of
^ bearings in a frame at its ends, the up and down movements of the satdfSa^being |
clockwise or anti -clockwise as the case may be ,and a protruding end of the cod ^°f
connected to an electronic sensor through a flexible coupling which is also
operationally connected to the drum feeder under the feeding hopper and controls
the rate of feed as per control amplitudes generated by the sensor.
(2) A method as claimed in Claim 1, wherein the lower end of the flapper is curved and the
outer curved surface gently rests on the accumulated material.
(3) A method as claimed in claims 1 to 2, wherein the electronic sensor has as its chief
components the following
(I) A zero potentiometer (Pz)
(II) A span potentiometer